US008114562B2
(12) United States Patent (10) Patent No.: US 8,114,562 B2 Ishigami et al. (45) Date of Patent: Feb. 14, 2012
(54) TWO-COMPONENT DEVELOPER, 2002fOO37466 A1 3/2002 Kambayashi et al. ... 43.0/108.23 2005, OO14079 A1 1/2005 Itakura et al...... 430,45 REPLENISHING DEVELOPER, AND 2005/0106488 A1 5/2005 Ida et al...... 430, 108.23 IMAGE-FORMING METHOD 2006, O154164 A1 7/2006 Kidokoro ...... 430, 108.23 2006/0172209 A1 8, 2006 Kidokoro (75) Inventors: Koh Ishigami, Mishima (JP); Kazuo 2007/O184372 A1 8/2007 Itakura et al...... 430/.454 Terauchi, Numazu (JP); Noriyoshi 2007/0224.531 A1 9/2007 Ida et al...... 430,102 Umeda, Susono (JP); Tetsuya Ida, 2008, 02994.75 A1 12/2008 Kidokoro Mishima (JP): Naoki Okamoto, FOREIGN PATENT DOCUMENTS Mishima (JP); Yojiro Hotta, Mishima JP O8-137135 5, 1996 (JP); Yoshinobu Baba, Yokohama (JP); JP 9-160293. A 6, 1997 Takayuki Itakura, Mishima (JP); JP 1O-312088 A 11, 1998 Takeshi Yamamoto, Yokohama (JP); JP 11-338 190 12/1999 Manami Haraguchi, Yokohama (JP); JP 2001-109.194 4/2001 JP 2001-142257 5, 2001 Kenta Kubo, Suntoh-gun (JP) JP 2001-154411 6, 2001 JP 2003-262980 A 9, 2003 (73) Assignee: Canon Kabushiki Kaisha, Tokyo (JP) JP 2004-117653 4/2004 JP 2004-117654 4/2004 (*) Notice: Subject to any disclaimer, the term of this JP 2004-117655 4/2004 patent is extended or adjusted under 35 JP 2004-354987. A 12, 2004 JP 2005-15251 A 1, 2005 U.S.C. 154(b) by 136 days. JP 2005-62857 A 3, 2005 JP 2005-141081 A 6, 2005 (21) Appl. No.: 12/716,714 JP 2005-195674 7/2005 JP 2005-249.972 9, 2005 (22) Filed: Mar. 3, 2010 JP 2005-316058 11, 2005 JP 2006-78981 A 3, 2006 (65) Prior Publication Data JP 2006-91373. A 4/2006 JP 2006-195079 T 2006 US 2010/O2O3438 A1 Aug. 12, 2010 JP 2006-209034 A 8, 2006 JP 2007-11293. A 1, 2007 JP 2008-083565 4, 2008 Related U.S. Application Data KR 10-2005-OOO9177 A 1, 2005 (60) Division of application No. 12/182,031, filed on Jul. WO 2006/O14007 A1 2, 2006 29, 2008, now Pat. No. 7,767,370, which is a OTHER PUBLICATIONS continuation of application No. PCT/JP2008/051648, filed on Feb. 1, 2008. Translation of IPRP for PCT/JP2008/051648, dated Aug. 13, 2009, 8 pageS. (30) Foreign Application Priority Data Japanese Office Action issued in the counterpart application No. 2008-556194 datedMar. 2, 2010, along with partial English language Feb. 2, 2007 (JP) ...... 2007-024381 translation—12 pages. Japanese Office Action issued in the counterpart application No. (51) Int. Cl. 2010-025710 dated Mar. 16, 2010, along with partial English lan GO3G 9/08 (2006.01) guage translation—12 pages. (52) U.S. Cl...... 430/111.4; 430/111.41; 430/111.35: 430/108.1:43.0/108.6:43.0/123.56; 430/123.57; Primary Examiner — Christopher Rodee 43Of 123.58 (74) Attorney, Agent, or Firm — Fitzpatrick, Cella, Harper & (58) Field of Classification Search ...... 430/111.4, Scinto 430/111.41, 111.35, 108.1, 123.56, 123.57, 430/123.58, 108.6 (57) ABSTRACT See application file for complete search history. A two-component developer containing a yellow toner and a magnetic carrier, wherein the yellow toner has the character (56) References Cited istics: (i) when the concentration of the yellow toner in a solution of the yellow toner in chloroform is represented by U.S. PATENT DOCUMENTS Cy (mg/ml) and the absorbance of the solution at a wave 5,342.876 A 8, 1994 Abe et al...... 524,493 length of 422 nm is represented by A422, a relationship 6,013,402 A 1/2000 Kanbayashi et al...... 430/.45 between Cy and A422 satisfies the relationship of 6,403.271 B1 6/2002 Suzuki et al...... 430, 108.6 6,905,808 B2 6/2005 Itakura et al...... 430,124 6.00 U.S. Patent Feb. 14, 2012 Sheet 2 of 17 US 8,114,562 B2 U.S. Patent Feb. 14, 2012 Sheet 3 of 17 US 8,114,562 B2 U.S. Patent Feb. 14, 2012 Sheet 4 of 17 US 8,114,562 B2 U.S. Patent Feb. 14, 2012 Sheet 5 Of 17 US 8,114,562 B2 U.S. Patent Feb. 14, 2012 Sheet 6 of 17 US 8,114,562 B2 O 105 PhotoSensitive Member O Toner O Magnetic Carrier Fig. 6 U.S. Patent Feb. 14, 2012 Sheet 7 Of 17 US 8,114,562 B2 U.S. Patent Feb. 14, 2012 Sheet 8 of 17 US 8,114,562 B2 32 30 3. A 38 s W 37 34 U.S. Patent Feb. 14, 2012 Sheet 9 Of 17 US 8,114,562 B2 Fig. 9 U.S. Patent Feb. 14, 2012 Sheet 10 of 17 US 8,114,562 B2 Fig. 1 O U.S. Patent Feb. 14, 2012 Sheet 11 of 17 US 8,114,562 B2 Direction in which Paper is passed Fig. 11 U.S. Patent Feb. 14, 2012 Sheet 12 of 17 US 8,114,562 B2 Fig. 12 U.S. Patent Feb. 14, 2012 Sheet 13 of 17 US 8,114,562 B2 Adhesive Application Step Carrier Fixing Step Toner Adhesion Step Centrifugal Separation Step Image Sampling Step Image Analysis Step Adhesive Force Calculation Step Fig. 13 U.S. Patent Feb. 14, 2012 Sheet 14 of 17 US 8,114,562 B2 Motor 14 1. 2 Power Supply Unit 15 Fig. 14 U.S. Patent Feb. 14, 2012 Sheet 15 of 17 US 8,114,562 B2 Fig. 15 U.S. Patent Feb. 14, 2012 Sheet 16 of 17 US 8,114,562 B2 23 s " " ' " 'il Fig. 16 U.S. Patent Feb. 14, 2012 Sheet 17 Of 17 US 8,114,562 B2 E1 Fig. 17 US 8,114,562 B2 1. 2 TWO-COMPONENT DEVELOPER, a predetermined density to be represented on recording paper REPLENISHING DEVELOPER, AND with a reduced toner laid-on level, whereby gradation is rep IMAGE-FORMING METHOD resented with an additionally narrow development contrast potential (Patent Document 1). In this case, the resultant Y This application is a division of application Ser. No. 5 characteristic is represented by the curve B of FIG. 1: the Y 12/182,031 filed Jul. 29, 2008, now U.S. Pat. No. 7,767,370, characteristic becomes sharp, and it may be difficult to obtain which is a continuation of International Application No. PCT/ high gradation. In addition, owing to the sharp Y characteris JP2008/051648, filed Feb. 1, 2008. tic, a change in image density due to a fluctuation in potential is large as compared to that of the conventional toner, so the BACKGROUND OF THE INVENTION 10 stability of the image density may reduce. The ability to obtain wide gradation and tingestability have 1. Field of the Invention been essential conditions in the POD market, so development The present invention relates to a two-component devel must be performed so that the Y characteristic shows a gradual oper, a replenishing developer, and an image-forming method slope even when a toner laid-on level is Small. An increase in each of which is used in an electrophotographic system, an 15 triboelectric charge quantity oftoner with an increased colo electrostatic recording system, or an electrostatic printing rant content is one useful approach to forming gradation by system. using the toner with the same development contrast potential 2. Description of the Related Art as a conventional one. Patent Document 1 does not refer to the A print-on-demand (POD) technology has been attracting triboelectric charge quantity of toner, and shows no sign of attention in recent years. The digital printing technology actively controlling the triboelectric charge quantity. involves directly printing an image without through a plate However, an increase in triboelectric charge quantity of making step. As a result, the technology can respond to Small toner increases the electrostatic adhesive force of the toner lot printing and a demand within a short delivery time, and with respect to the Surface of a carrier or photosensitive mem can respond also to printing in which contents vary from sheet ber, with the result that developing performance and transfer to sheet (variable printing) and dispersion printing in which 25 ring performance reduce, and an image density reduces in multiple output devices are activated on the basis of one piece Some cases. There has been a proposal specifying a relation of data by utilizing a communication facility. Accordingly, ship between a toner charge quantity and an adhesive force the technology has advantage over the conventional offset between toner and a carrier (Patent Document 2). According printing. When one attempts to apply an image-forming to Patent Document 2, setting each of the toner charge quan method based on an electrophotographic system to a POD 30 tity and the adhesive force within a predetermined range market, tinge stability as well as the three basic elements of allows the formation of a high-quality image with no image printing, that is, a high speed, high image quality, and a low failure. However, in the documents it is not assumed that running cost must be improved. In view of the foregoing, region of a triboelectric charge quantity requested of toner essential performance requested of toner is as follows: the with so large a colorant content that a toner consumption can toner achieves an image with quality and definition each of 35 be reduced, so the adhesive force between the carrier and the which is comparable to or higher than the conventional one toner is still strong, and a Sufficient image density cannot be without narrowing a color reproduction range, and a toner obtained in Some cases. consumption is reduced. Further, the toner must respond to a Accordingly, in order that an image may be formed with a reduction in fixation energy and various kinds of recording Smallertoner laid-on level than a conventional one, the image paper. 40 must be efficiently developed with toner which has a large The following proposal has been made (Patent Document colorant content, contains a colorant having high dispersibil 1): a toner laid-on level is set to 0.35 mg/cm or less, and a ity, shows high coloring power, and has a high triboelectric deficiency (blister or the like) occurring at the time offixation charge quantity. Toner having the following characteristics is Suppressed while a toner consumption is reduced, whereby and a developer containing the toner have been desired: the a high-quality, good-appearance color image stably having a 45 toner contains a colorant having good dispersibility, and has a wide color reproduction range is formed. According to the high triboelectric charge quantity, a high-resolution, high proposal, a high-quality, good-appearance color image which definition image can be efficiently developed with the toner, rages to a small extent, is excellent in fixing performance, and and each of the toner and the developer can stably express stably has a wide color reproduction range can beformed. The good image quality even when continuously used without use of toner having a toner particle in which the amount of a 50 impairing the color gamut, chroma, and lightness of the colorant is increased in a conventional electrophotographic image. system is expected to have a certain improving effect on Patent Document 1: JP 2005-195674. A fixing property, but may reduce the chroma, or narrow the Patent Document 2: JP 2006-195079 A color gamut, of an image. A possible cause for the foregoing is as follows: as a result of an increase in amount of the 55 SUMMARY OF THE INVENTION colorant, the dispersibility of the colorant reduces, and the hue of the toner changes, with the result that the chroma of the The present invention has solved the above problems of the image reduces, and the color gamut of the image narrows. related art. As described above, an increase in amount of a colorant in That is, an object of the present invention is to provide a a toner particle is apt to reduce the density stability and 60 two-component developer, a replenishing developer, and an gradation of animage at the time of the long-term use oftoner. image-forming method each of which allows a high-defini Conventional toner corresponds to the curve A of FIG. 1 tion image to be obtained with a smaller toner laid-on level where the axis of abscissa indicates a potential (development than a conventional one. contrast) and the axis of ordinate indicates a density (it should Another object of the present invention is to provide a be noted that the characteristic represented by the curve is 65 two-component developer and a replenishing developer each referred to as “y characteristic'). An increase in content of the of which can respond to an increase in printing speed, and colorant as compared to that of the conventional toner allows allows an image with a stable tinge to be continuously output US 8,114,562 B2 3 4 even in long-term use, and an image-forming method involv used, a high-resolution, high-definition image is achieved ing the use of any Such developer. while atoner consumption is reduced, and the toner can stably The present invention relates to a two-component devel express good image quality even when continuously used oper including a cyan toner having cyan toner particles each without impairing the color gamut, chroma, and lightness of having at least a binder resin and a colorant, and an external 5 the image. additive, and a magnetic carrier, in which the cyan toner has Further feature of the present invention will become appar the following characteristics: ent from the following description of exemplary embodi (i) when a concentration of the cyan toner in a solution of ments (with reference to the attached drawings). the cyan toner in chloroform is represented by Cc (mg/ml) and an absorbance of the solution at a wavelength of 712 nm 10 BRIEF DESCRIPTION OF THE DRAWINGS is represented by A712, a relationship between Cc and A712 satisfies the following expression (1) FIG. 1 is a view showing the characteristic of toner. FIG. 2 is a view showing a relationship between a contrast potential and a (saturation) image density in toner. (ii) a lightness L* and a chroma C* of the cyan toner 15 FIG.3 is a view for explaining the relationship between the determined in a powder state satisfy relationships of contrast potential and the (Saturation) image density in the 25,0sL*s40.0 and 50,0sC*sé0.0; and tOner. (iii) an absolute value for a triboelectric charge quantity of FIG. 4 is a view for explaining a change in Y characteristic the cyan toner measured by a two-component method using of toner. the cyan toner and the magnetic carrier is 50 mC/kg or more FIG. 5 is a view showing the hue profile of each of a and 120 mC/kg or less. conventional toner and a toner showing high coloring power Further, the present invention relates to a two-component in the ab plane of CIELAB. developer including a magenta toner having magenta toner FIG. 6 is a schematic view showing the flow of a replen particles each having at least a binder resin and a colorant, and ishing developer in an image-forming apparatus using the an external additive, and a magnetic carrier, in which the 25 developer. magenta toner has the following characteristics: FIG. 7 is an outline constitution view as an embodiment of (i) when a concentration of the magentatoner in a solution a full-color image-forming apparatus using a replenishing of the magenta toner in chloroform is represented by Cm developer of the present invention. (mg/ml) and an absorbance of the solution at a wavelength of FIG. 8 is a schematic sectional view showing an example of 538 nm is represented by A538, a relationship between Cm 30 the constitution of a Surface modification apparatus prefer and A538 satisfies the following expression (3) ably used in the production of a toner of the present invention. FIG.9 is a schematic plan view showing the constitution of a dispersion rotor provided to the Surface modification appa (ii) a lightness L* and a chroma C* of the magenta toner ratus of FIG. 8. determined in a powder state satisfy relationships of 35 FIG.10 is a view showing an example of the constitution of 35,0sL*s45.0 and 60,0sC*s 72.0; and an apparatus for measuring the specific resistance of the mag (iii) an absolute value for a triboelectric charge quantity of netic component of a magnetic carrier. the magenta toner measured by a two-component method FIG. 11 is a view for explaining an image and a method using the magentatoner and the magnetic carrier is 50 mC/kg each employed in evaluation for a lowest fixation tempera or more and 120 mC/kg or less. 40 ture. In addition, the present invention relates to a two-compo FIG. 12 is an outline view of a sample the adhesive force of nent developer including a yellow toner having yellow toner which is measured. particles each having at least a binder resin and a colorant, and FIG. 13 is a view showing all steps for the measurement of an external additive, and a magnetic carrier, in which the the adhesive force. yellow toner has the following characteristics: 45 FIG. 14 is an outline view of a spin coater. (i) when a concentration of the yellow toner in a solution of FIG. 15 is a schematic view showing the inside of the rotor the yellow toner in chloroform is represented by Cy (mg/ml) of a centrifugal separator. and an absorbance of the solution at a wavelength of 422 mm FIG. 16 is a view showing a toner adhesion step. is represented by A422, a relationship between Cy and A422 FIG. 17 is a view showing the outline of the principle of a satisfies the following expression (5) 50 centrifugal separation method. DESCRIPTION OF REFERENCE NUMERALS (ii) a lightness L* and a chroma C* of the yellow toner determined in a powder state satisfy relationships of 11 lower electrode 85,0sL*s 95.0 and 100,0sC*s 115.0; and 55 12 upper electrode (iii) an absolute value for a triboelectric charge quantity of 13 insulator the yellow toner measured by a two-component method using 14 ampere meter the yellow toner and the magnetic carrier is 50 mC/kg or more 15 volt meter and 120 mC/kg or less. 16 voltage stabilizer In addition, the present invention relates to an image-form 60 17 magnetic carrier ing method involving the use of the above two-component 18 guide ring developer. 61a photosensitive member According to the present invention, there can be provided a 62a charging roller two-component developer and a replenishing developer each 63a developing device having the following characteristics, and an image-forming 65 64a transferring blade method involving the use of any Such developer: toner having 65a replenishing developer container a large colorant content and showing strong coloring power is 67a exposure light US 8,114,562 B2 5 6 68 transfer material bearing member the central portion of a line in a line image or letter image on 69 detach charging device an image is not transferred, and only an edge portion of the 70 fixing apparatus line is transferred may occur. 71 fixing roller On the other hand, when the above value (A712/Cc) is 8.15 72 pressure roller or more, Sufficient coloring power can be obtained, but the 75 heating means lightness of the toner reduces, so the resultant image is apt to 76 heating means be dark and to have reduced sharpness. In addition, the 79 cleaning member amount of a colorant exposed to the Surface of the toner tends 80 driver roller to increase, so the charging performance of the toner may 10 deteriorate, triboelectric charge quantity of toner may 81 belt driven roller decrease, fogging may occur in an image blank portion, or the 82 belt static eliminator inside of an developing assembly may be contaminated 83 resist roller owing to toner Scattering. 85 toner concentration detecting sensor In the case of a two-component developer containing a 101 replenishing developer storing container 15 magentatoner, a magentatoner having the following charac 102 developing device teristic is used: when the concentration of the magenta toner 103 cleaning unit in a solution of the magentatoner in chloroform is represented 104 developer collecting container by Cm (mg/ml) and the absorbance of the solution at a wave 105 replenishing developer introduction port length of 538 nm is represented by A538, a value determined 106 discharge port by dividing A538 by Cm (A538/Cm) is larger than 2.00 and Pa image-forming unit smaller than 6.55. The above value (A538/Cm) is more pref Pb image-forming unit erably larger than 2.40 and smaller than 4.90 in order that Pc image-forming unit needed coloring power may be obtained. When the above Pd image-forming unit value (A538/Cm) is 2.00 or less, the degree of coloring of the E resistance measurement cell 25 toner per unit mass reduces, so a toner laid-on level on record L sample width ing paper must be increased and the thickness of a toner layer on the paper must be increased in order that a needed degree DESCRIPTION OF THE EMBODIMENTS of coloring may be obtained. As a result, a toner consumption cannot be reduced, with the result that dust may be generated Hereinafter, the Best Mode for carrying out the present 30 at the time of transfer or fixation, or a “transfer void phe invention will be described in detail. nomenon in which the central portion of a line in a line image The inventors of the present invention have made extensive or letter image on an image is not transferred, and only an studies. As a result, the inventors have found that, when (1) a edge portion of the line is transferred may occur. relationship between the concentration C (mg/ml) of a solu On the other hand, when the above value (A538/Cm) is tion of toner in chloroform and the absorbance A of the 35 6.55 or more, sufficient coloring power can be obtained, but solution at a predetermined wavelength, (2) the lightness L* the lightness of the toner reduces, so the resultant image is apt and chroma C* of the toner determined in a powder state, and to be dark and to have reduced sharpness. In addition, the (3) the absolute value for the triboelectric charge quantity of amount of a colorant exposed to the Surface of the toner tends the toner are each adjusted to fall within a predetermined to increase, so the charging performance of the toner may numerical range, the toner can achieve a high-resolution, 40 deteriorate, and triboelectric charge quantity of toner may high-definition image, and can stably provide an image with decrease, fogging may occur in an image blank portion, or the good image quality when continuously used without impair inside of an developing assembly may be contaminated ing the color gamut, chroma, and lightness of the image. owing to toner Scattering. Thus, the inventors have reached the present invention. Further, in the case of a two-component developer contain In addition, the present invention aims to achieve the above 45 ing a yellow toner, a yellow toner having the following char object by developing an image with toner having a large acteristic is used: when the concentration of the yellow toner colorant content and showing strong coloring power as toner in a solution of the yellow toner in chloroform is represented having a high charge quantity while Suppressing a change in by Cy (mg/ml) and the absorbance of the solution at a wave hue as one detrimental effect when the colorant content is length of 422 nm is represented by A422, a value determined increased. 50 by dividing A422 by Cy (A422/Cy) is larger than 6.00 and In the case of a two-component developer containing a smaller than 14.40. The above value (A422/Cy) is more pref cyan toner, a cyan toner having the following characteristic is erably larger than 7.00 and smaller than 12.00 in order that used: when the concentration of the cyantoner in a solution of needed coloring power may be obtained. When the above the cyan toner in chloroform is represented by Cc (mg/ml) value (A422/Cy) is 6.00 or less, the degree of coloring of the and the absorbance of the solution at a wavelength of 712 nm 55 toner per unit mass reduces, so a toner laid-on level on record is represented by A712, a value determined by dividing A712 ing paper must be increased and the thickness of a toner layer by CC (A712/Cc) is larger than 2.00 and smaller than 8.15. on the paper must be increased in order that a needed degree The above value (A712/Cc) is more preferably larger than of coloring may be obtained. As a result, a toner consumption 2.40 and smaller than 4.90 in order that needed coloring cannot be reduced, with the result that dust may be generated power may be obtained. When the above value (A712/Cc) is 60 at the time of transfer or fixation, or a “transfer void phe 2.00 or less, the degree of coloring of the toner per unit mass nomenon in which the central portion of a line in a line image reduces, so a toner laid-on level on recording paper must be or letter image on an image is not transferred, and only an increased and the thickness of a toner layer on the paper must edge portion of the line is transferred may occur. be increased in order that a needed degree of coloring may be On the other hand, when the above value (A422/Cy) is obtained. As a result, a toner consumption cannot be reduced, 65 14.40 or more, sufficient coloring power can be obtained, but with the result that dust may be generated at the time of the lightness of the toner reduces, so the resultant image is apt transfer or fixation, or a “transfer void phenomenon in which to be dark and to have reduced sharpness. In addition, the US 8,114,562 B2 7 8 amount of a colorant exposed to the Surface of the toner tends C* of the magenta toner exceeds 72.0, a color balance is apt to increase, so the charging performance of the toner may to be lost when a full-color image is formed. deteriorate, and triboelectric charge quantity of toner may In the case of the two-component developer containing a decrease, fogging may occur in an image blank portion, or the yellow toner, with regard to the lightness L* and chroma C* inside of an developing assembly may be contaminated 5 of the yellow toner determined in a powder state, the L* is owing to toner Scattering. 85.0 or more and 95.0 or less, or preferably 87.0 or more and Each of the above values (A712/Cc), (A538/Cm), and 95.0 or less. When the L* of the yellow toner falls within the (A422/Cy) can be controlled by adjusting the kind and above range, the representable color space of an image amount of a colorant to be incorporated into toner, and one becomes sufficiently wide, and the quality of the image is 10 improved. When the L* of the yellow toner is less than 85.0, skilled in the art can adjust these values. a representable color space may be small when a full-color In the case of the two-component developer containing a image is formed by combining the toner with a toner having cyan toner, the lightness L* and chroma C* of the cyan toner any other color. On the other hand, when the L* of the yellow determined in a powder state satisfy the following relation toner exceeds 95.0, a desired image density is hardly ships: the L* is 25.0 or more and 40.0 or less, or preferably 15 obtained. An increase in toner amount on recording paper for 28.0 or more and 40.0 or less, and the C* is 50.0 or more and obtaining a needed image density makes the generation of 60.0 or less. When each of the lightness L* and chroma C* of dust at the time of transfer or fixation, or the occurrence of a the cyan toner determined in a powder state falls within the transfer Void. In addition, in association with the increase in above range, the representable color space of an image is toner amount, the Stepheight of the toner enlarges, and image Sufficiently wide, the quality of the image becomes good, and quality reduces in some cases. a toner amount on recording paper can be reduced. In addition, the chroma C* of the yellow toner is 100.0 or When the L* of the cyan toner is less than 25.0, a repre more and 115.0 or less. When the C* of the yellow toner falls sentable color space may be small when a full-color image is within the above range, the representable color space of an formed by combining the toner with a toner having any other image is Sufficiently wide, and a toner amount on recording color. On the other hand, when the L* of the cyan toner 25 paper can be reduced. When the C* of the yellow toner is less exceeds 40.0, a desired image density is hardly obtained. An than 100.0, a desired image density is hardly obtained. On the increase in toner amount on recording paper for obtaining a other hand, when the C* of the yellow toner exceeds 115.0, a needed image density makes the generation of dust at the time color balance is apt to be lost when a full-color image is of transfer or fixation, or the occurrence of a transfer void. In formed. addition, in association with the increase in toner amount, the 30 Each of the lightness L* and chroma C* of any one of the Stepheight of the toner enlarges, and image quality reduces in above toners determined in a powder state can be appropri SO CaSS. ately adjusted to fall within the above range by controlling the When the C* of the cyan toner is less than 50.0, a desired kind and amount of a colorant to be incorporated into the image density is hardly obtained. On the other hand, when the toner, and the dispersed State of the colorant. In addition, C* of the cyan toner exceeds 60.0, a color balance is apt to be 35 those numerical values can be adjusted depending on the kind lost when a full-color image is formed. The hue oftoner with of the binder resin, a production method for the binder resin, an increased colorant content changes, and the L* and C of and the conditions under which the binder resin is produced. the toner change in many cases. This is probably because an However, an image developed with toner showing high increase in colorant content causes the reagglomeration of a coloring power in a conventional system may be deficient in pigment to reduce the coloring power of the toner, thereby 40 tinge stability when the toner is used over a long time period. causing the change in hue. Therefore, the use of toner show Accordingly, the use of toner having a high triboelectric ing high coloring power can reduce a toner laid-on level, and charge quantity is of importance. can reduce a toner consumption. Each of the cyan, magenta, and yellow toners each used in In the case of the two-component developer containing a the two-component developer of the present invention (each magentatoner, with regard to the lightness L* and chroma C* 45 of which may hereinafter be simply referred to as “toner of the of the magenta toner determined in a powder state, the L* is present invention” or “toner”) is characterized in that the 35.0 or more and 45.0 or less. When the L* of the magenta absolute value for the triboelectric charge quantity of the toner falls within the above range, the representable color toner measured by a two-component method using the toner space of an image becomes Sufficiently wide, and the quality and a magnetic carrier is 50 mC/kg or more and 120 mC/kg or of the image is improved. When the L* of the magenta toner 50 less. In the case of a developer using a toner the above abso is less than 35.0, a representable color space may be small lute value for the triboelectric charge quantity of which is less when a full-color image is formed by combining the toner than 50 mC/kg, when a toner showing strong coloring power with a toner having any other color. On the other hand, when to be used in the present invention is used, a Y characteristic the L* of the magenta toner exceeds 45.0, a desired image becomes sharp, a fluctuation in density becomes large Owing density is hardly obtained. An increase in toner amount on 55 to the long-term use of the developer, and the density is recording paper for obtaining a needed image density makes deficient in stability in some cases. On the other hand, when the generation of dust at the time of transfer or fixation, or the the above absolute value for the triboelectric charge quantity occurrence of a transfer Void. In addition, in association with of the toner exceeds 120 mC/kg, an image density or transfer the increase in toner amount, the step height of the toner efficiency may reduce. This is probably because an electro enlarges, and image quality reduces in some cases. 60 static adhesive force between the magnetic carrier and the In addition, the chroma C* of the magenta toner is 60.0 or Surface of a photosensitive member becomes large. more and 72.0 or less, or preferably 62.0 or more and 72.0 or A method of adjusting the above absolute value for the less. When the C* of the magenta toner falls within the above triboelectric charge quantity of each of the above toners range, the representable color space of an image is sufficiently within the above range is, for example, a method involving wide, and a toner amount on recording paper can be reduced. 65 controlling the kind of an external additive, the kind and When the C* of the magentatoner is less than 60.0, a desired particle diameter of a Surface treatment agent, and the per image density is hardly obtained. On the other hand, when the centage by which a toner particle is coated with the external US 8,114,562 B2 9 10 additive, a method involving optimizing the kind of a coat toner amount one half of that of the conventional toner. In resin for the magnetic carrier or the amount in which the order that the Saturation image density may be obtained by carrier is coated with the resin, or a method involving adding using the toner with improved coloring power of the present a particle or a charge control agent into a coat resin. invention at a laid-on level of 0.25 mg/cm and a contrast The reason why Such toner having a high triboelectric potential Vcont of 500 V, gradation can be formed in accor charge quantity as described above is needed is as described dance with a Y characteristic comparable to that of the con below. ventional toner as long as an image is developed with toner For example, suppose a developer in which the triboelec the Saturation triboelectric charge quantity of which is twice tric charge quantity of conventional toner is -40 mC/kg, and as high as that of the conventional toner, that is, -80 mC/kg. a toner laid-on level on a photosensitive member at 10 As described above, in order that high gradation may be Vcont=500V is 0.5 mg/cm and a system using the developer. maintained and a fluctuation in density may be suppressed In order that a Saturation image density may be obtained by while the laid-on level oftoner with improved coloring power using the conventional toner, there is given such Y character is reduced, an image must be efficiently developed with the istic as represented by the curve A of FIG. 1 where the axis of toner as toner having a high triboelectric charge quantity. abscissa indicates a contrast potential and the axis of ordinate 15 In addition, an adhesive force (F50) between each of the indicates an image density. Development is performed by toners and a magnetic carrier by a centrifugal separation filling the contrast potential with the charge of the toner. An a method when the absolute value for the triboelectric charge point in FIG. 2 is the point at which the saturation density is quantity of the toner measured by the two-component method obtained by the conventional toner. using the toner and the magnetic carrier is 50 mC/kg is pref On the other hand, when toner showing high coloring erably 11 nN or more and 16 nN or less. power like the toner of the present invention is used, if the When the adhesive force falls within the above range, the coloring power is twice as high as that of the conventional releasing performance of the toner with respect to the carrier toner, the Saturation image density is obtained with a laid-on becomes Suitable, the occurrence of toner Scattering can be level of 0.25 mg/cm which is one half of that of the conven favorably suppressed, and high development efficiency or tional toner, so needed toner is used for development at a b 25 high transfer efficiency can be obtained. point in FIG. 2 with Vcont=250 V. When the Vcont is addi A method of adjusting the above adhesive force (F50) tionally increased from the b point, the laid-on level within the above range is, for example, a method involving increases, but the image density has already been Saturated, adjusting the circularity of a toner particle of the toner, or a and the density no longer increases (see FIG. 3). When the method involving controlling the kind of an external additive, Vcont reaches 500 V, the toner laid-on level becomes 0.5 30 the kind and particle diameter of a surface treatment agent, mg/cm to reach the a point. At the apoint, an excess amount and the percentage by which a toner particle of the toner is of the toner showing high coloring power is present, with the coated with the external additive. It should be noted that a result that the resultant image is dark and grave, and shows a method of adjusting the adhesive force by controlling a large change in its hue. FIG. 5 shows the hue profile of each parameter related to the carrier will be described later. of the conventional toner and the tonershowing high coloring 35 In addition, the magnetic carrier to be used in the two power in the ab plane of CIELAB. A solid line corresponds component developer of the present invention (which may to the conventional toner, and a dotted line corresponds to the hereinafter be simply referred to as “magnetic carrier of the toner showing high coloring power. The hue profile corre present invention' or "magnetic carrier) is not particularly sponds to the case where an image is developed with the toner limited as long as the triboelectric charge quantity of toner showing high coloring power so that a characteristic curve 40 measured when the magnetic carrier is mixed with the toner exceeds a b point in FIG. 3 to reach an a' point in the figure. falls within a predetermined range, and a magnetic carrier When the characteristic curve reaches the a' point, the curve containing at least a magnetic component and a resin compo of FIG. 5 curves toward thea axis, whereby the hue of the nent can be preferably used. From the viewpoint of a reduc resultant image changes. A reduction in lightness of the image tion in adhesive force with respect to the toner, a magnetic occurs simultaneously with the change. Accordingly, the 45 carrier containing resin-containing magnetic particles saturation image density has only to be output with the lowest obtained by incorporating a resin into the pores of porous toner amount in which the image density is saturated. How magnetic core particles, the magnetic carrier having the fol ever, when a system for developing an image with toner lowing characteristics, is preferably used: when the packed showing high coloring power the image density of which is bulk density and true density of the porous magnetic core saturated at a laid-on level of 0.25 mg/cm and Vcont=250 V 50 particles are represented by p1 (g/cm) and p2 (g/cm), is assumed, gradation cannot help being formed with the respectively, p1 is 0.80 or more and 2.40 or less and p1/p2 is Vcont one half of a conventional one (-250V) as represented 0.20 or more and 0.42 or less, and the specific resistance of by the curve B of FIG. 1, with the result that the stability of the each of the porous magnetic core particles is 1.0x10 S2 cm or image involves the following problem: a fluctuation in den more and 5.0x107 S2 cm or less. In addition, the above mag sity with a fluctuation in potential becomes large. If gradation 55 netic carrier particularly preferably has the following charac can be obtained with the Vcont comparable to that of the teristic: when the 50% particle diameter on a volume basis of conventional toner (500 V) while a laid-on level is reduced the magnetic carrier is represented by D50, the average break in half, in other words, the slope of a Y characteristic can be as ing strength of the magnetic carrier having a particle diameter gradual as that of the conventional toner like a curve A of D50-5 um or more and D50+5 um or less is represented by (dotted line) obtained by extending the curve C (broken line) 60 P1 (MPa), and the average breaking strength of the magnetic of FIG. 4 along the axis of abscissa, a change in hue caused by carrier having a particle diameter of 10 um or more and less the presence of an excess amount of toner showing high than 20 pum is represented by P2 (MPa), P2/P1 is 0.50 or more coloring power can be Suppressed, and, at the same time, the and 1.10 or less. stability of the hue against a fluctuation in potential can be When the packed bulk density p 1 of the porous magnetic improved. To this end, the charge quantity of the toner must be 65 core particles is set to be 0.80 g/cm or more and 2.40 g/cm increased so that the contrast potential Vcont comparable to or less, the prevention of the adhesion of the magnetic carrier that of the conventional toner (=500V) may be filled with the to a photosensitive drum and an improvement in dot repro US 8,114,562 B2 11 12 ducibility of an electrostatic latent image can be achieved. ethylvaleronitrile, and azobiscyclohexanecarbonitrile; Setting p1 within the above range can improve the dot repro hydrogen carbonates of metals such as Sodium, potassium, ducibility while Suppressing the adhesion of the magnetic and calcium; ammonium hydrogen carbonate; ammonium carrier to the photosensitive drum. The dot reproducibility is carbonate; calcium carbonate; an ammonium nitrate salt; an preferably improved because the toner of the present inven azide compound; 4,4'-oxybis(benzenesulfohydrazide); allyl tion shows so high coloring power that the collapse of a dot or bis(sulfohydrazide); and diaminobenzene. toner scattering is apt to be remarkable. Examples of the above organic fine particles include: Wax: In addition, at the same time, when the packed bulk density thermoplastic resins such as polystyrene, an acrylic resin, and and true density of the porous magnetic core particles are a polyester resin; and thermosetting resins such as a phenol represented by p1 (g/cm) and p2 (g/cm), respectively, set 10 ting p1/O2 to 0.20 or more and 0.42 or less can prevent a resin, a polyester resin, a urea resin, a melamine resin, and a reduction in image density while Suppressing the adhesion of silicone resin. Each of them is turned into fine particles before the magnetic carrier to the photosensitive drum even when use. A known method can be employed as a method of turning 100,000 images each having a wide image area (for example, each of them into fine particles. For example, each of them is an image area ratio of 50%) are printed under a normal 15 pulverized into particles each having a desired particle diam temperature, low-humidity (for example, 23° C./5 RH 96) eter in a pulverization step. In the pulverization step, for environment. example, the following method is employed: each of them is Further, setting the specific resistance of each of the porous coarsely pulverized with a grinder Such as a crusher, a ham magnetic core particles to 1.0x10 S2 cm or more and 5.0x107 mer mill, or a feather mill, and, furthermore, the coarsely S2 cm or less can prevent a reduction in density at the back end pulverized products are finely pulverized with a Kryptron of a solid image. system manufactured by Kawasaki Heavy Industries, a Super The inventors of the present invention consider the reason rotor manufactured by Nisshin Engineering Inc., a Turbo mill for the foregoing to be as described below. (RSS rotor/SNNB liner) manufactured by Turbo Kogyo Co., When an image is developed with the toner, counter charge Ltd., or an air-jet pulverizer. opposite in polarity to the toner remains in the magnetic 25 Alternatively, the following procedure may be performed: carrier. The charge pulls back the toner used for the develop fine particles are classified after pulverization so that the grain ment onto the photosensitive drum, thereby reducing the den size distribution of the particles is adjusted. An apparatus for sity at the back end portion. However, setting the specific the classification is, for example, a classifier or a screen resistance of each of the porous magnetic core particles classifier such as an Elbow Jet based on an inertial classifica within the above range can cause the counter charge remain 30 tion system (manufactured by Nittetsu Mining Co., Ltd.) or a ing in the magnetic carrier to escape toward a developing Turboplex based on a centrifugal classification system sleeve through the magnetic component of the magnetic car (manufactured by Hosokawa Micron Corporation). rier while Suppressing the leak of the charge. As a result, a The diameters, diameter distribution, and pore ratio of the force for pulling back the toner toward the photosensitive pores of the magnetic component can be adjusted depending drum weakens, and a reduction in image density even at the 35 back end of the Solid image is Suppressed. on the diameters, diameter distribution, and amount of those Next, a specific approach to adjusting for example, each of fine particles to be used. the packed bulk density, the true density, and the specific In addition, a material for the magnetic component is, for resistance described above within the above range will be example, (1) an iron powder with an oxidized Surface or an described. Each of the packed bulk density, the true density, 40 iron powder with an unoxidized surface, (2) a metal particle and the specific resistance described above can be adjusted formed of for example, any one of lithium, calcium, magne within the above range by controlling, for example, the kind sium, nickel, copper, Zinc, cobalt, manganese, chromium, and of the element of the magnetic component in each magnetic a rare earth element, (3) an alloy particle containing a metal core particle, and the crystalline diameters, pore diameters, Such as iron, lithium, calcium, magnesium, nickel, copper, pore diameter distribution, and pore ratio of the porous mag 45 Zinc, cobalt, manganese, chromium, or a rare earth element, netic core particles. or an oxide particle containing any one of these elements, or For example, each of the following approaches (1) to (4) (4) a magnetite particle or a ferrite particle. can be employed: The above ferrite particle is a sintered body represented by (1) the growth rate of a crystal of the magnetic component is the following formula: controlled by adjusting a temperature at the time of the sin 50 tering of the magnetic component; (2) a blowing agent orapore-forming agent formed of organic where w--x-y+z=100 mol % (each of w, x, and y may repre fine particles is added to the magnetic component so that a sent 0, but the case where all of them each represent 0 is pore is generated; excluded), and L. M., and Q each represent a metal atom (3) the pore diameters, the pore diameter distribution, the pore 55 selected from Ni, Cu, Zn, Li, Mg,Mn, Sr., Ca, and Ba. ratio, and the like are adjusted by controlling the kind and Examples of the ferrite particle include a magnetic Lifer amount of a blowing agent, and the time period for which the rite. Mn-Zn ferrite, Mn. Mg ferrite, MnMgSr ferrite, magnetic component is sintered; or Cu-Zn ferrite, Ni Znferrite, Ba ferrite, and Mn ferrite. Of (4) the pore diameters, the pore diameter distribution, and the those, the Mnferrite or the Mn-Znferrite each containing an pore ratio are adjusted by controlling the diameter, diameter 60 Mn element is preferable from the viewpoint of the easy distribution, and amount of a pore-forming agent, and the control of the growth rate of the crystal. time period for which the magnetic component is sintered. The specific resistance of each of the porous magnetic core The above blowing agent is not particularly limited as long particles is adjusted by reducing the Surface of the magnetic as it is a Substance which generates a gas in association with component of the magnetic carrier through a heat treatment its vaporization or decomposition at 60 to 180° C. Examples 65 for the magnetic component in an inert gas instead of con of the above blowing agent include: blowing, azo polymer trolling the kind of a magnetic material for the carrier. For ization initiators such as azobisisobutyronitrile, azobisdim example, the following approach is suitably employed: the US 8,114,562 B2 13 14 magnetic component is subjected to a heat treatment under an acrylate and a styrene-acrylic acid copolymer, a styrene inert gas (Such as nitrogen) atmosphere at 600° C. or higher butadiene copolymer, an ethylene-vinyl acetate copolymer; and 1,000° C. or lower. polyvinyl chloride; polyvinyl acetate; a polyvinylidene fluo When the 50% particle diameter on a volume basis of the ride resin; a fluorocarbon resin; a perfluorocarbon resin; a above magnetic carrier is represented by D50, the average solvent-soluble perfluorocarbon resin: polyvinyl pyrroli breaking strength of the magnetic carrier having a particle done; a petroleum resin; a novolac resin; aromatic polyester diameter of D50-5 um or more and D50+5 um or less is resins such as a saturated alkylpolyester resin, polyethylene represented by P1 (MPa), and the average breaking strength terephthalate, polybutylene terephthalate, and polyallylate; a of the magnetic carrier having a particle diameter of 10 um or polyamide resin; a polyacetal resin; a polycarbonate resin; a more and less than 20 um is represented by P2 (MPa), P2/P1 10 polyetherSulfone resin; a polysulfone resin; a polyphenylene is preferably 0.50 or more and 1.10 or less. Setting P2/P1 Sulfide resin; and a polyetherketone resin. within the above range can: favorably Suppress the generation Examples of the thermosetting resin can include the fol of a flaw on a photosensitive drum when the developer is used lowing: A phenol resin; a modified phenol resin; a maleic over a long time period; and favorably prevent the occurrence resin; an alkyd resin; an epoxy resin; an acrylic resin; unsat of fogging. P2/P1 is more preferably 0.70 or more and 1.10 or 15 urated polyester obtained by polycondensation of maleic less. anhydride, terephthalic acid, and a polyhydric alcohol; aurea The inventors of the present invention consider the reason resin; a melamine resin; a urea-melamine resin; a Xylene for the foregoing to be as described below. resin; a toluene resin; a guanamine resin; a melamine-guan The magnetic carrier having a particle diameter of 10um or amine resin; an acetoguanamine resin; a glyptal resin; afuran more and less than 20um tends to have a smaller resin content resin; a silicone resin; a polyimide resin; a polyamideimide in each of the porous magnetic core particles than that of the resin; a polyetherimide resin; and a polyurethane resin. magnetic carrier having a particle diameter around the 50% Resins obtained by denaturing those resins are also permit particle diameter on a Volume basis. The magnetic carrier ted. Of those, a fluorine-containing resin Such as a polyvi containing resin-containing magnetic particles each having a nylidene fluoride resin, a fluorocarbon resin, or a perfluoro Small resin content is apt to have a low strength, and is apt to 25 carbon resin, or a solvent-soluble perfluorocarbon resin, an be broken by a stress applied to the magnetic carrier at the acrylic-denatured silicone resin, or a silicone resin is prefer time of its stirring in a developing device or a stress applied by able because these resins each have high wettability with a regulating member on a developing sleeve so as to be turned respect to the magnetic component of the magnetic carrier. into fine particles. In addition, when additionally fine mag To be more specific, a conventionally known silicone resin netic components as particles are produced by the breakage, 30 can be used as the silicone resin. Examples of the silicone these particles have a high true specific gravity and are hard, resin include: a straight silicone resin composed only of an so, when the particles migrate onto a photosensitive drum, the organosiloxane bond; and a silicone resin denatured with, for particles are apt to scratch the Surface layer of the photosen example, an alkyd, polyester, an epoxy, or urethane. sitive drum at the time of the cleaning of the photosensitive A commercially available straight silicone resin is, for drum So as to be responsible for the generation of a scratch. As 35 example, a KR271, KR255, or KR152 manufactured by Shin a result, the particles are responsible for the generation of Etsu Chemical Co., Ltd., oran SR2400 or SR2405 manufac white stripes in a solid image. tured by Dow Corning Toray Co., Ltd. A commercially avail Therefore, the resin component must be properly incorpo able denatured silicone resin is, for example, KR206 (alkyd rated into each porous magnetic core particle particularly in denatured), KR5208 (acrylic-denatured), ES1001N (epoxy the magnetic carrier having a particle diameter of 10 um or 40 denatured), or KR305 (urethane-denatured) manufactured by more and less than 20 um so that P2/P1 is 0.50 or more. In Shin-Etsu Chemical Co., Ltd., or SR2115 (epoxy-denatured) addition, setting P2/P1 within the above range uniformizes or SR2110 (alkyd-denatured) manufactured by Dow Corning charge-providing performance for the toner, and can provide Toray Co., Ltd. good triboelectric charging performance. A general method of incorporating the resin component The adjustment of P2/P1 in the range of 0.50 or more to 45 into each of the porous magnetic core particles involves: 1.10 or less can be achieved by: controlling the pores of the diluting the resin component with a solvent; and adding the porous magnetic core particles, the composition of the resin Solution to the magnetic component of the magnetic carrier. component to be incorporated, and the step of incorporating The solvent used here has only to be capable of dissolving the resin component; and uniformly incorporating the resin each resin component. In the case of a resin Soluble in an component. 50 organic solvent, examples of the organic solvent include tolu In order that the resin component may be uniformly incor ene, Xylene, celloSolve butyl acetate, methyl ethyl ketone, porated, a solution of the resin component to be incorporated methyl isobutyl ketone, and methanol. In the case of a water more preferably has a viscosity (25°C.) of 0.6 Pa's or more soluble resin component or an emulsion type resin compo and 100 Pa's or less. Setting the viscosity of the solution of the nent, water has only to be used. A method of adding the resin resin component within the above range allows the resin 55 component diluted with a solvent into each of the porous component to penetrate into the pores uniformly and Suffi magnetic core particles is, for example, a method involving: ciently, and allows the resin component to adhere to the impregnating the particles with the resin component by an magnetic component properly, whereby the resin component application method such as a dipping method, a spray is in a state of being favorably incorporated. method, a brush coating method, a fluidized bed method, or a The above resin component to be incorporated into each 60 kneading method; and Volatilizing the solvent after the porous magnetic core particle is not particularly limited as impregnation. long as the resin component shows high wettability with In addition, the magnetic carrier of the present invention respect to the magnetic component of the magnetic carrier, may have another resin component with which the surface of and each of a thermoplastic resin and a thermosetting resin the magnetic carrier is coated as well as the above resin may be used. 65 component to be incorporated into each porous magnetic core Examples of the thermoplastic resin includes the follow particle. In that case, the resin component to be incorporated ing: a polystyrene; acrylic resins such as polymethyl meth into each magnetic core particle and the resin component with US 8,114,562 B2 15 16 which the Surface of the magnetic carrier is coated may be uneven shapes, so the treatment must be performed while the identical to or different from each other. An acrylic resin is produced fine powders are discharged to the outside, and more preferably used as the resin component with which the hence a mechanical impact force more than necessary is Surface of the magnetic carrier is coated because the durabil needed for obtaining a desired sphericity. As a result, the ity of the magnetic carrier can be improved. following detrimental effect arises: a redundant heat quantity The 50% particle diameter on a volume basis (D50) of the is applied to a toner Surface, and a wax amount on the toner above magnetic carrier is preferably 20um or more and 70 um Surface increases. In addition, an extremely small fine powder or less from the viewpoints of triboelectric charging perfor is mainly responsible for making the spent of the toner to the mance for the toner, and the prevention of carrier adhesion to carrier remarkable. In contrast, in the apparatus shown in each an image region and of fogging. 10 of FIGS. 8 and 9, powders are classified while the same air The 50% particle diameter (D50) of the magnetic carrier flow applying a mechanical impact force is not stopped, so the can be adjusted within the above range by performing air powders can be efficiently discharged to the outside without classification or screen classification. being agglomerated again. The toner preferably has the following characteristic: the Additionally detailed description will be given below. The toner having a circle-equivalent diameter (number basis) 15 surface modification apparatus shown in FIG. 8 is formed of: measured with a flow-type particle image measuring appara a casing; ajacket (not shown) through which cooling water or tus having an image processing resolution of 512x512 pixels antifreeze can pass; a dispersion rotor 36 as Surface modifi (each measuring 0.37 um by 0.37 um) of 2.0 um or more has cation means, the dispersion rotor 36 being present in the an average circularity of 0.945 or more and 0.970 or less. casing and attached to a central rotation axis, the dispersion Setting the average circularity of the toner within the above rotor 36 having multiple square disks or cylindrical pins 40 on range improves contact between the toner and the magnetic its upper Surface, and the dispersion rotor 36 being a disk-like carrier, provides good developing performance, and Sup rotator rotating at a high speed; a liner 34 placed on the outer presses the embedding of the external additive in a toner periphery of the dispersion rotor 36 with a certain interval particle Surface. Further, setting the average circularity within between the liner and the rotor, the liner 34 being provided the above range provides good cleaning performance. 25 with a large number of grooves on its Surface (it should be Means for adjusting the average circularity of the toner is noted that no grooves may be present on the liner Surface); a not particularly limited; any one of various methods such as a classification rotor 31 as means for classifying Surface-modi method involving sphering pulverized toner particles by a fied raw materials depending on a predetermined particle mechanical impact method and a method involving atomizing diameter; a cold air introduction port 35 for introducing cold a molten mixture with a disk or a multi-fluid nozzle in the air 30 air; a raw material feeding port 33 for introducing raw mate to provide spherical toner particles can be adopted for adjust rials to be treated; a discharge valve 38 placed so as to be ing the above average circularity within the above range. openable and closable for freely adjusting a surface modifi When toner particles are obtained by the mechanical cation time; a product discharge port 37 for discharging a impact method out of the above methods, a wax amount on powder after a treatment; and a cylindrical guide ring 39 as the surface of each toner particle can be simply controlled. In 35 guiding means for partitioning a space between the classifi addition, the method is more preferable because the surface cation rotor 31 and a set of the dispersion rotor 36 and the liner profile of each toner particle can also be simply controlled. into a first space 41 before the introduction of the raw mate The wax amount on the Surface of each toner particle can be rials to the classification rotor 31 and a second space 42 for adjusted by controlling: the physical properties of raw mate introducing particles from which a fine powder has been rials, in particular, the viscoelasticity of a resin; or conditions 40 removed by classification by the classification rotor 31 to under which the toner particles are produced, in particular, Surface treatment means. A gap portion between the disper conditions for melting and kneading, and a condition for sion rotor 36 and the liner 34 is a surface modification Zone, polymerization. However, a method for the adjustment is not and the classification rotor 31 and its peripheral portion con particularly limited as long as desired physical properties can stitute a classification Zone. be obtained. A mechanical grinder used in the mechanical 45 In the Surface modification apparatus constituted as impact method is, for example, a HYBRIDIZER manufac described above, when finely pulverized products are loaded tured by NARAMACHINERY CO.,LTD., a Kryptron sys from the raw material feeding port 33 in a state where the tem manufactured by Kawasaki Heavy Industries, or a Super discharge valve 38 is closed, the loaded finely pulverized rotor manufactured by Nisshin Engineering Inc. products are firstly sucked by a blower (not shown) and clas An apparatus shown in FIG. 8 is preferably used in order 50 sified by the classification rotor 31. At this time, a fine powder that a toner having an appropriate wax amount on a toner having a particle diameter equal to or Smaller than the prede particle surface and an average circularity of 0.945 to 0.970 termined particle diameter obtained as a result of the classi out of various kinds oftoners may be favorably obtained. The fication is removed by being continuously discharged to the use of the apparatus can provide a toner capable of achieving outside of the apparatus. A coarse powder having a particle excellent fixing performance and excellent transferring per 55 diameter equal to or larger than the predetermined particle formance at high levels. diameter is guided to the Surface modification Zone by a FIG. 8 is a schematic sectional view showing an example of circulation flow generated by the dispersion rotor 36 along the the constitution of a Surface modification apparatus prefer inner periphery of the guide ring 39 (the second space 42) by ably used in the production of the toner of the present inven virtue of a centrifugal force. tion. FIG.9 is a schematic plan view showing the constitution 60 The raw materials guided to the Surface modification Zone of a dispersion rotor possessed by the Surface modification receive a mechanical impact force between the dispersion apparatus of FIG.8. The apparatus intends to obtain desired rotor 36 and the liner 34 to be subjected to a surface modifi shapes and desired performance by applying a mechanical cation treatment. The particles with their surfaces modified impact force while discharging a produced fine powder to the ride on cold air passing through the inside of the apparatus, outside of the apparatus. In the case of a mechanical sphering 65 whereby the particles are guided to the classification Zone treatment, considerably small fine powders produced at the along the outer periphery of the guide ring 39 (the first space time of pulverization typically agglomerate again to provide 41). A fine powder generated at that time is discharged by the US 8,114,562 B2 17 18 classification rotor 31 to the outside of the apparatus again, invention is improved by incessantly feeding a new carrier and a coarse powder rides on the circulation flow to return to having high charge-providing performance together with a the Surface modification Zone again. Then, the coarse powder new toner from the replenishing developer, whereby an addi repeatedly receives a Surface modification action. After a tionally stable image output can be obtained even when the predetermined time period has passed, the discharge valve 38 developer is used over a long time period. is opened, and the Surface-modified particles are collected It should be noted that, in an image-forming apparatus from the product discharge port 37. using Such replenishing developer as described above, the Investigation conducted by the inventors of the present magnetic carrier the Volume of which has been increased by invention have shown that a time period commencing on the virtue of the magnetic carrier in the replenishing developer loading of the finely pulverized products from the raw mate 10 rial feeding port 33 and ending on the opening of the dis with which the developing device is replenished overflows charge valve (cycle time) and the number of revolutions of the from the developing device in an amount corresponding to the dispersion rotor in the step of the surface modification treat increase in Volume, and is taken in a developer collecting ment with the above Surface modification apparatus each play auger, transported to a replenishing developer container or an important role in controlling the average circularity of the 15 another collecting container, and discharged. toner and a wax amount on a toner particle Surface. Length In addition, the toners of the present invention, or the ening the cycle time or increasing the circumferential speed magnetic carriers of the present invention, used in the two of the dispersion rotor is effective in increasing the average component developer with which the above developing circularity. In addition, in contrast, shortening the cycle time device is filled first (which may hereinafter be referred to as or reducing the circumferential speed is effective in Suppress “starting developer) and the above replenishing developer ing the transmittance of the toner. In particular, unless the may be identical to or different from each other. circumferential speed of the dispersion rotor is equal to or In addition, an image-forming method of the present inven larger than a certain value, the toner cannot be subjected to tion is an image-forming method including: a charging step of efficient sphering, so the toner must be subjected to sphering charging an electrostatic latent image bearing member; an with the cycle time lengthened, with the result that the trans 25 electrostatic latent image forming step of forming an electro mittance of the toner is increased more than necessary in static latent image on the electrostatic latent image bearing Some cases. A circumferential speed of the dispersion rotor of member charged in the charging step; a developing step of 1.2x10 mm/s or more and a cycle time of 5 to 60 seconds are developing the electrostatic latent image formed on the elec effective in increasing the circularity of the toner to cause trostatic latent image bearing member with the two-compo each of the average circularity and transmittance of the toner 30 nent developer of the present invention to formatoner image: to fall within the above range while Suppressing the transmit a transferring step of transferring the toner image on the tance to a level equal to or lower than a predetermined level. electrostatic latent image bearing member onto a transfer The two-component developer of the present invention can material through or without through an intermediate transfer be used also as a replenishing developer for use in a two body; and a fixing step offixing the toner image to the transfer component developing method including: performing devel 35 material, and is characterized in that a laid-on level of a toner opment while replenishing a developing device with the of a monochromatic Solid image portion (having an image replenishing developer, and discharging an excess magnetic density of 1.5) in the unfixed toner image formed on the carrier in the developing device from the developing device. transfer material is in the range of 0.10 mg/cm or more to With such constitution, the performance of the two-compo 0.50 mg/cm or less. The laid-on level of the toner of the nent developer in the developing device can be maintained. 40 monochromatic Solid image portion in the unfixed toner When the two-component developer is used as the replenish image formed on the transfer material is more preferably in ing developer, the above toner is used at a mass ratio of 2 parts the range of 0.10 mg/cm or more to 0.35 mg/cm or less. by mass or more and 50 parts by mass or less with respect to When the above laid-on level of the toner is less than 0.10 1 part by mass of the above magnetic carrier. The use of the mg/cm, even if coloring power per toner particle is above replenishing developer allows the performance of the 45 improved, the number of toner particles is insufficient, and a two-component developer in the developing device to be density does not increase owing to an influence of the forma stably maintained over a long time period. As a result, an tion of recording paper in Some cases. In addition, when the image which: shows a small fluctuation in charging perfor above laid-on level of the toner exceeds 0.50 mg/cm, the step mance of the toner, has good dot reproducibility; and under height of the toner becomes remarkable. In addition, dust at goes fogging to a small extent can be obtained. When an 50 the time of transfer or fixation may become remarkable. image is formed with a developer using a toner showing high The toner of the present invention can be obtained by a coloring power perparticle like the toner of the present inven Suspension polymerization method, an emulsion agglomera tion, fogging is apt to be remarkable as compared to the case tion method, an association polymerization method, or a where an image is formed with an ordinary developer that kneading pulverization method, and a production method for does not have such characteristic as described above. Accord 55 the toner is not particularly limited. ingly, the ability of the developer to provide an image under The toner of the present invention has a weight-average going fogging to a small extent as described above is an particle diameter of preferably 4.0 m or more and 8.0 um or advantage over the ordinary developer. In addition, in the case less, more preferably 4.0 um or more and 7.0 Lum or less, or of a developer using a tonershowing high coloring power like still more preferably 4.5 um or more and 6.5 um or less. the present invention, animage is developed with a low devel 60 Setting the weight-average particle diameter of the toner oper consumption, so a stress to be applied to each of the toner within the above range can Sufficiently improve dot reproduc and a carrier is expected to be larger than that in a developer ibility and transfer efficiency. The weight-average particle using a conventional toner. The carrier that has received the diameter of the toner can be adjusted by the classification of stress often shows charge-providing performance reduced as toner particles at the time of the production of the toner or by compared to that in an initial state, so its durability may 65 the mixing of classified products. deteriorate. In view of the foregoing, in the present invention, A binder resin to be used in each of the toner particles of the durability of the two-component developer of the present which the toner of the present invention is constituted pref US 8,114,562 B2 19 20 erably contains a resin having a polyester unit. The term carboxylic acid component containing a polyvalent carboxy "polyester unit refers to a portion originating from polyester. lic acid which is trivalent or more. Examples of the polyvalent The above polyester unit is formed by the condensation carboxylic acid component which is trivalent or more include, polymerization of ester monomers. Examples of the ester but not limited to, 1,2,4-benzenetricarboxylic acid, 1,2,5- monomers include: polyhydric alcohol components; and car 5 benzenetricarboxylic acid, 1,2,4-naphthalenetricarboxylic boxylic acid components such as a polyvalent carboxylic acid, 2.5.7-naphthalenetricarboxylic acid, and 1,2,4,5-ben acid, a polyvalent carboxylic anhydride, and a polyvalent Zenetetracarboxylic acid, and anhydrides and ester com carboxylate having two or more carboxyl groups. pounds of these acids. The content of the polyvalent carboxy Examples of a dihydric alcohol component out of the poly lic acid component which is trivalent or more in ester hydric alcohol component include bisphenol A alkylene 10 oxide adducts Such as polyoxypropylene(2.2)-2.2-bis(4-hy monomers to be subjected to condensation polymerization is droxyphenyl)propane, polyoxypropylene(3.3)-2.2-bis(4-hy preferably 0.1 to 1.9 mol % with reference to all the mono droxyphenyl)propane, polyoxyethylene(2.0)-2.2-bis(4-hy CS. droxyphenyl)propane, polyoxypropylene(2.0)- Further, the preferable examples of the above resin having polyoxyethylene(2.0)-2.2-bis(4-hydroxyphenyl)propane, 15 a polyester unit include: (a) a hybrid resin in which the poly and polyoxypropylene(6)-2.2-bis(4-hydroxyphenyl)pro ester unit and a vinyl polymer unit are chemically bonded to pane, ethylene glycol, diethylene glycol, triethylene glycol, each other; (b) a mixture of a hybrid resin and a vinyl poly 1.2-propylene glycol. 1,3-propylene glycol, 1,4-butanediol. mer; (c) a mixture of a polyester resin and a vinyl polymer; (d) neopentyl glycol, 1,4-butenediol. 1,5-pentanediol, 1.6-hex a mixture of a hybrid resin and a polyester resin; and (e) a anediol. 1,4-cyclohexanedimethanol, dipropylene glycol, mixture of a polyester resin, a hybrid resin, and a vinyl poly polyethylene glycol, polypropylene glycol, polytetramethyl C. ene glycol, bisphenol A, and hydrogenated bisphenol A. The above hybrid resin is formed by, for example, bonding Examples of a trihydric or higher alcohol component out of as a result of an ester exchange reaction between a polyester the polyhydric alcohol component include sorbitol, 1.2.3,6- unit and a vinyl polymer unit obtained by the polymerization hexanetetrol, 1.4-Sorbitan, pentaerythritol, dipentaerythritol, 25 of a monomer component having a carboxylate group Such as tripentaerythritol. 1,2,4-butanetriol, 1.2.5-pentanetriol, glyc an acrylate or a methacrylate. erol, 2-methylpropanetriol, 2-methyl-1,2,4-butanetriol, trim The hybrid resin is preferably a graft copolymer or block ethylolethane, trimethylolpropane, and 1,3,5-trihydroxym copolymer using a vinyl polymer as a stem polymer and a ethylbenzene. polyester unit as a branch polymer. Examples of a carboxylic acid component forming a poly 30 ester unit include the following: aromatic dicarboxylic acids It should be noted that the above vinyl polymer unit means such as phthalic acid, isophthalic acid, and terephthalic acid a portion originating from a vinyl polymer. The above vinyl or anhydrides thereof, alkyldicarboxylic acids such as suc polymer unit or vinyl polymer is obtained by the polymeriza cinic acid, adipic acid, sebacic acid, and azelaic acid or anhy tion of a vinyl monomer. drides thereof. Succinic acid Substituted with an alkyl group 35 Examples of the vinyl monomer may include the follow having 6 to 12 carbonatoms oranhydrides thereof, and unsat ing: styrene monomer oran acrylic-based monomer; a meth urated dicarboxylic acids such as fumaric acid, maleic acid, acrylic monomer, a monomer of ethylenically unsaturated and citraconic acid or anhydrides thereof. monoolefins; a monomer of vinylesters; a monomer of As the preferred example of a resin containing a polyester vinylethers; a monomer of vinylketones; a monomer of N-vi unit, mentioned is a polyester resin obtained by a condensa 40 nyl compounds; and other vinyl monomers. tion polymerization using a bisphenol derivative typified by a Examples of the styrene monomer may include the follow structure represented by the following general formula as an ing: styrene; o-methylstyrene; m-methylstyrene; p-methyl alcohol component and a carboxylic acid component (such as styrene; p-methoxystyrene; p-phenylstyrene; p-chlorosty fumaric acid, maleic acid, maleic anhydride, phthalic acid, rene; 3,4-dichlorostyrene: p-ethylstyrene; 2,4- terephthalic acid, dodecenylsuccinic acid, trimellitic acid, or 45 dimethylstyrene; p-n-butylstyrene; p-tert-butylstyrene; p-n- pyromellitic acid) derived from a divalent or higher carboxy hexylstyrene; p-n-octylstyrene; p-n-nonylstyrene; p-n- lic acid, an anhydride thereof, or a lower alkylester thereof as decylstyrene; and p-n-dodecylstyrene. carboxylic acid component. The polyester resin is preferred Examples of the acrylic monomer may include the follow in the present invention because of its excellent charging ing: acrylates Such as methyl acrylate, ethyl acrylate, n-butyl property. 50 acrylate, isobutyl acrylate, propyl acrylate, n-octyl acrylate, dodecyl acrylate, 2-ethylhexyl acrylate, Stearyl acrylate, dim ethylaminoethyl acrylate, and phenyl acrylate; acrylic acids; Chem 1 and acrylamides. CH Examples of the methacrylic monomer may include the 55 following: methacrylates such as ethyl methacrylate, propyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, i-o-o-O--O-o-on n-octyl methacrylate, dodecyl methacrylate, 2-ethylhexyl it, methacrylate, Stearyl methacrylate, phenyl methacrylate, dimethylaminoethyl methacrylate, and diethylaminoethyl (where R represents an ethylene or propylene group, X and y 60 methacrylate; methacrylic acids; and methacrylamides. each represent an integer of one or more, and X-y has an Examples of the monomer of ethylenically unsaturated average value of 2 to 10.) monoolefins include ethylene, propylene, butylene, and In addition, the preferable examples of the above resin isobutylene. having a polyester unit include polyester resins each having a Examples of the monomer of vinylesters include vinyl crosslinked structure. Each of the polyester resins each hav 65 acetate, vinyl propionate, and vinyl benzoate. ing a crosslinked structure is obtained by a condensation Examples of the monomer of vinylethers include vinyl polymerization reaction between a polyhydric alcohol and a methyl ether, vinyl ethyl ether, and vinyl isobutyl ether. US 8,114,562 B2 21 22 Examples of the monomer of vinyl ketones include vinyl quantity. An aluminum pan is used for a measurement sample, methyl ketone, vinyl hexyl ketone, and methyl isopropenyl and the measurement is performed by setting an empty panas ketone. a reference. Examples of the monomer of N-vinyl compounds include The content of the above release agent is preferably 1 to 15 N-vinylpyrrole, N-vinylcarbazole, N-vinylindole, and N-vi parts by mass, or more preferably 3 to 10 parts by mass with nylpyrrolidone. respect to 100 parts by mass of the binder resin in the toner Examples of the other kinds of vinyl monomers include particles. When the content of the release agent is 1 to 15 parts vinylnaphthalenes and acrylic acid derivatives or methacrylic by mass, the agent can exert excellent releasing performance, acid derivatives Such as acrylonitrile, methacrylonitrile, and for example, when an oilless fixing system is adopted. acrylamide. 10 The toner may contain a known charge control agent. One kind of the vinyl monomers may be used, or two or Examples of the charge control agent include organometallic more kinds of them can be used in combination. complexes, metal salts, chelate compounds, carboxylic acid Examples of the polymerization initiator used when pro derivatives such as carboxylic acid metal salts, carboxylic ducing a vinyl polymer unit, a vinyl-based polymer, or a vinyl 15 anhydrides, and carboxylates, condensates of aromatic com resin may include the following: azo or diazo polymerization pounds, and phenol derivatives such as bisphenols and calix initiators such as 2,2'-azobis-(2,4-dimethylvaleronitrile), aS. 2,2'-azobisisobutyronitrile, 1,1'-azobis(cyclohexane-1-car Examples of the organometallic complexes include bonitrile), 2,2'-azobis-4-methoxy-2,4-dimethylvaleronitrile, monoazo metal complexes, acetylacetone metal complexes, and azobisisobutyronitrile; peroxide polymerization initia hydroxycarboxylic acid metal complexes, polycarboxylic tors or initiators having a peroxide on a sidechain, such as acid metal complexes, and polyol metal complexes. benzoylperoxide, methylethylketoneperoxide, diisopropylp Of those, a metal compound of an aromatic carboxylic acid eroxycarbonate, cumene hydroperoxide, t-butylhydroxyper is preferable from the viewpoint of an improvement in charge oxide, di-t-butylperoxide, dicumylperoxide, 2,4-dichlo rising performance of the toner. robenzoylperoxide, lauroylperoxide, 2.2-bis(4,4-t- 25 The content of the above charge control agent is preferably butylperoxycyclohexyl)propane, and tris-(t-butylperoxy) 0.1 to 10.0 parts by mass, or more preferably 0.2 to 5.0 parts trizaine; persulfates such as potassium persulfate and by mass with respect to 100 parts by mass of the binder resin ammonium persulfate; and hydrogen peroxide. in the toner particles. Adjusting the amount of the charge Further, examples of polymerization initiators which are control agent in the toner within the above range can reduce a radically polymerizable and has three or more functional 30 change in charge quantity of the toner in any one of various groups include the following. Radically polymerizable poly environments ranging from a high-temperature, high-humid functional polymerization initiators such as tris(t-butylper ity environment to a low-temperature, low-humidity environ oxy)trizaine, vinyltris(t-butylperoxy)silane, 2.2-bis(4,4-di-t- ment. butylperoxycyclohexyl)propane, 2.2-bis(4,4-di-t- The toner contains a colorant. The colorant may be a pig amylperoxycyclohexyl)propane, 2.2-bis(4,4-di-t- 35 ment or a dye, or a combination of them. octylperoxycyclohexyl)propane, and 2.2-bis(4,4-di-t- Examples of the dye may include the following: C.I. Direct butylperoxycyclohexyl)butane. Red 1, C.I. Direct Red 4, C.I. Acid Red 1, C.I. Basic Red 1, Both the two-component developer and the replenishing C.I. Mordant Red 30, C.I. Direct Blue 1, C.I. Direct Blue 2, developer of the present invention may be preferably used in C.I. Acid Blue 9, C.I. Acid Blue 15, C.I. Basic Blue 3, C.I. an electrophotography process having an oilless fixing sys 40 Basic Blue 5, C.I. Mordant Blue 7, C.I. Direct Green 6, C.I. tem. As such, it is preferable that the toner includes a release Basic Green 4, and C.I. Basic Green 6. agent. Examples of the pigment may include the following: min Examples of the above release agent include: aliphatic eral Fast Yellow, Navel Yellow, Naphthol Yellow S. Hansa hydrocarbon waxes such as low-molecular-weight polyeth Yellow G, Permanent Yellow NCG, Tartrazine Lake, Molyb ylene, low-molecular-weight polypropylene, a polyolefin 45 denum Orange, Permanent Orange GTR, Pyrazolone Orange, copolymer, a polyolefin wax, a microcrystalline wax, a par Benzidine Orange G. Permanent Red 4R. Watching Red cal affin wax, and a Fischer-Tropsch wax; oxides of aliphatic cium salt, eosine lake, Brilliant Carmine 3B, Manganese Vio hydrocarbon waxes such as a polyethylene oxide wax, or let, Fast Violet B, Methyl Violet Lake, Cobalt Blue, Alkali block copolymers of the waxes; waxes mainly composed of Blue Lake, Victoria Blue Lake, Phthalocyanine Blue, Fast aliphatic acid esters such as a carnauba wax, a montanic acid 50 Sky Blue, Indanthrene Blue BC, Chrome Green, Pigment ester wax, and behenyl behenate; and partially or wholly Green B, Malachite Green Lake, and Final Yellow Green G. deacidified aliphatic acid esters such as a deacidified car In addition, when the two-component developer and nauba wax. replenishing developer of the present invention are each used It is preferable that the toner contain such release agent as as a developer for forming a full-color image, the toner can described above, and have an endothermic peak in the tem 55 contain a coloring pigment for each of magenta, cyan, and perature range of 30 to 200°C. in the endothermic curve of the yellow colors. toner in differential scanning calorimetry. In addition, the Examples of the magenta coloring pigment may include temperature of the highest endothermic peak out of the endot the following: C.I. Pigment Red 1,2,3,4,5,6,7,8,9, 10, 11, hermic peaks is particularly preferably 50 to 110°C. in terms 12, 13, 14, 15, 16, 17, 18, 19, 21, 22, 23, 30, 31, 32, 37,38, 39, of low-temperature fixability and durability. 60 40, 41,48, 49, 50, 51, 52,53,54, 55, 57,58, 60, 63, 64, 68, 81, A differential scanning calorimeter is, for example, a 83, 87,88, 89,90, 112, 114, 122, 123, 163,202,206, 207,209, DSC-7 manufactured by PerkinElmer Co., Ltd., a DSC2920 and 238; C.I. Pigment Violet 19; and C.I. Vat Red 1, 2, 10, 13, manufactured by TA Instruments, or a Q1000 manufactured 15, 23, 29, and 35. by TA Instruments. In measurement with the apparatus, the The toner particles can includes only the magenta pig melting point of each of indium and Zinc is used for correcting 65 ments, but when the dye and the pigment are combined, the temperature of the detecting portion of the apparatus, and sharpness of a developer and image quality of a full color the heat of fusion of indium is used for correcting a heat image are improved. US 8,114,562 B2 23 24 Examples of the magenta dye may further include the The surface of the silica fine particles obtained by a sol-gel following: Oil soluble dyes such as C.I. Solvent Red 1, 3, 8, method may be subjected to a hydrophobic treatment and 23, 24, 25, 27, 30, 49, 81, 82, 83, 84, 100, 109, and 121, C.I. used. As the hydrophobic treatment agent, a silane compound Disperse Red 9, C.I. Solvent Violet 8, 13, 14, 21, and 27, and is preferably used. Examples of the silane compound include: C.I. Disperse Violet 1; and basic dyes such as C.I. Basic Red hexamethyl disilaZane; monochlorosilanes such as trimethyl 1, 2, 9, 12, 13, 14, 15, 17, 18, 22, 23, 24, 27, 29, 32, 34,35, 36, chlorosilane and triethyl chlorosilane; monoalkoxysilanes 37,38, 39, and 40, and C.I. Basic Violet 1, 3, 7, 10, 14, 15, 21, Such as trimethyl methoxysilane and trimethyl ethoxysilane; 25, 26, 27, and 28. monoaminosilanes such as trimethylsilyl dimethylamine and Examples of the cyan coloring pigment may include the trimethylsilyl diethylamine; and monoacyloxysilanes such as 10 trimethylacetoxysilane. following: C.I. Pigment Blue 2, 3, 15, 15:1, 15:2, 15:3, 16, In addition, fine particles each serving as an external addi and 17; C.I. Acid Blue 6: C. I. Acid Blue 45; and copper tive as well as the above inorganic fine particles having a phthalocyanine pigments having a phthalocyanine skelton number average particle diameter of 80 nm or more and 300 substituted by 1 to 5 methyl phthalimide groups. nm or less may be added to the toner, fine particles having a Ayellow coloring pigment may include the following: C.I. 15 number average particle diameter of 5 nm or more and 60 nm Pigment Yellow 1,2,3,4,5,6,7, 10, 11, 12, 13, 14, 15, 16, 17, or less are preferable. The external addition of the fine par 23, 65, 73,74, 83, 93, 97,155, and 180; and C.I. VatYellow 1, ticles except the above inorganic fine particles to the toner can 3, and 20. improve the flowability or transferring performance of the A black pigment is, for example, carbon black Such as toner. The fine particles preferably contain inorganic fine furnace black, channel black, acetylene black, thermal black, particles selected from titanium oxide, aluminum oxide, and or lamp black, or a magnetic powder Such as magnetite or silica fine particles. ferrite. Alternatively, a magenta dye and a magenta pigment, The surface of each of the above fine particles is preferably a yellow dye and a yellow pigment, and a cyan dye and a cyan subjected to a hydrophobic treatment. The hydrophobic treat pigment may be combined to tone a black color, and, further ment is preferably performed with any one of the hydropho more, carbon black described above may be used in combi 25 bic treatment agents such as: various titanium coupling nation with any Such dye or pigment. agents; coupling agents such as a silane coupling agent, ali In addition, the toner contains inorganic fine particles each phatic acids and metal salts of the acids; silicone oil; and a serving as an external additive. combination of two or more of them. The inorganic fine particles have a number average particle Examples of the titanium coupling agent used in the hydro diameter of preferably 80 nm or more and 300 nm or less, or 30 phobic treatment include the following: tetrabutyl titanate, more preferably 90 nm or more and 150 nm or less. When the tetraoctyl titanate, isopropyl triisoStearoyl titanate, isopropyl number average particle diameter of the inorganic fine par tridecylbenzene sulfonyl titanate, and bis(dioctlypyrophos ticles falls within the above range, the inorganic fine particles phate)oxyacetate titanate. are hardly embedded in the toner particles, and can each Examples of the silane coupling agent used in the hydro continue to function as a spacer even when images are con 35 phobic treatment may include the following: Y-(2-aminoet tinuously output over a long time period. In addition, mean hyl)aminopropyltrimethoxysilane, Y-(2-aminoethyl)amino while, the inorganic fine particles are hardly liberated from propylmethyldimethoxysilane, the toner particles. As a result, even in the case of a toner the Y-methacryloxypropyltrimethoxysilane, N-3-(N-vinylben absolute value for the triboelectric charge quantity of which is Zylaminoethyl)-y-aminopropyltrimethoxysilane hydrochlo 50 mC/kg or more and 120 mC/kg or less, toner release from 40 ride, hexamethyldisilazane, methyltrimethoxysilane, butylt a carrier does not become remarkable, and an image can be rimethoxysilane, isobutyltrimethoxysilane, efficiently developed. In addition, not a state where the toner hexyltrimethoxysilane, octyltrimethoxysilane, decyltri and a photosensitive drum contact with each other at the methoxysilane, dodecyltrimethoxysilane, phenyltrimethox Surface of each toner particle but a state where the inorganic ysilane, o-methylphenyl trimethoxysilane, and p-methylphe fine particles and the photosensitive drum contact with each 45 nyl trimethoxysilane. other in a point contact manner can be maintained, releasing Examples of the fatty acid and metal salts to be used in the performance between the toner and the photosensitive drum hydrophobic treatment include the following. Long chain is also maintained, and a reduction in transfer efficiency can fatty acids such as undecyl acid, lauric acid, tridecyl acid, be suppressed. Such inorganic fine particles are externally dodecyl acid, myristic acid, palmitic acid, pentadecyl acid, added to the tonerata content of preferably 0.1 to 3.0 mass %, 50 Stearic acid, heptadecyl acid, arachic acid, montan acid, oleic or more preferably 0.5 to 2.5 mass %. acid, lionic acid, and arachidonic acid. Examples of the met Examples of the above inorganic fine particles include als for the metal salts include Zinc, iron, magnesium, alumi silica fine particles, alumina fine particles, and titanium oxide num, calcium, Sodium, and lithium. fine particles. In the case of the silica fine particles, all kinds Examples of the above silicone oil for a hydrophobic treat of silica fine particles produced by employing a convention 55 ment include a dimethyl silicone oil, a methyl phenyl silicone ally known technology Such as a vapor-phase decomposition oil, and an amino-modified silicone oil. method, a combustion method, or a deflagration method can The above hydrophobic treatment is preferably performed be used. by adding 1 to 30 mass % (more preferably 3 to 7 mass %) of In addition, the above inorganic fine particles are prefer any one of the above hydrophobic treatment agents to the ably particles produced by a known sol-gel method involving: 60 inorganic fine particles to coat the inorganic fine particles. removing a solvent from a silica Sol Suspension obtained by The hydrophobicity of each of the inorganic fine particles the hydrolysis and condensation reaction of an alkoxysilane subjected to the hydrophobic treatment is not particularly with a catalyst in an organic solvent in which wateris present; limited. For example, a hydrophobicity determined by a drying the remainder, and turning the dried product into par methanol titration test for the inorganic fine particles after the ticles. The silica fine particles produced by the sol-gel method 65 hydrophobic treatment (methanol wettability; indicator each have a Substantially spherical shape, are monodisperse, showing wettability with respect to methanol) preferably falls and serve as excellent spacer particles. within the range of 40 to 95. US 8,114,562 B2 25 26 The total content of the above external additive in the toner The image-forming apparatus of the present invention is is preferably 0.1 to 5.0 mass %, or more preferably 0.5 to 4.0 obtained by providing the four image-forming units formed mass %. Alternatively, the external additive may be a combi of the first image-forming unit Pa, and the second image nation of multiple kinds of fine particles. forming unit Pb, the third image-forming unit PC, and the When a full-color image is formed, the cyan toner, the fourth image-forming unit Pd each of which: has the same magenta toner, and the yellow toner described above can be constitution as that of the first image-forming unit Pa; and is used in combination. In addition, at that time, the laid-on level different from the first image-forming unit Pain the color of of a toner for each color is in the range of preferably 0.10 a color toner held in a developing device. For example, a mg/cm or more to 0.50 mg/cm or less, or more preferably yellow toner is used in the first image-forming unit Pa, a 0.10 mg/cm or more to 0.35 mg/cm or less. 10 FIG. 7 shows an outline view when the image-forming magentatoner is used in the second image-forming unit Pb, a method of the present invention is applied to a full-color cyan toner is used in the third image-forming unit PC, and a image-forming apparatus. black toner is used in the fourth image-forming unit Pd. As a A first image-forming unit Pa, a second image-forming result, the respective color toners are sequentially transferred unit Pb, a third image-forming unit PC, and a fourth image 15 onto the transfer material at the transfer portions of the forming unit Pd are provided for the main body of the full respective image-forming units. In the step, the respective color image-forming apparatus, and images different from color toners are Superimposed on the same transfer material each other in color are formed on a transfer material through by one movement of the transfer material while the toners are latent image formation, development, and transfer processes. in register. After the completion of the Superimposition, the The constitution of each of the image-forming units pro transfer material is detached from the upper portion of the vided for the image-forming apparatus will be described by transfer material bearing member 68 by a detach charging taking the first image-forming unit Paas an example. device 69. After that, the transfer material is transported by The first image-forming unit Pa is provided with a photo transport means such as a transport belt to a fixing apparatus sensitive member 61 a having a diameter of 30 mm as an 70 where the final full-color image is obtained by only one electrostatic latent image bearing member, and the photosen 25 fixation. sitive member 61a is rotated and moved in the direction The fixing apparatus 70 has a fixing roller 71 and a pressure indicated by an arrow a. A charging roller 62a like a primary roller 72, and the fixing roller 71 has heating means 75 and 76 charging device as charging means is placed so that a mag in itself. netic brush for charging formed on the surface of the sleeve of An unfixed color toner image transferred onto the transfer the roller having a diameter of 16 mm is in contact with the 30 surface of the photosensitive member 61a. Exposure light material passes through a portion where the fixing roller 71 67a is applied to the photosensitive member 61a from an and pressure roller 72 of the fixing apparatus 70 are brought exposing device (not shown) for forming an electrostatic into press contact with each other so as to be fixed onto the latent image on the photosensitive member 61a the surface of transfer material by the actions of heat and a pressure. which is uniformly charged by the charging roller 62a. A 35 In FIG. 7, the transfer material bearing member 68 is an developing device 63a as developing means for developing endless, belt-like member, and the belt-like member is moved the electrostatic latent image borne by the photosensitive by a driver roller 80 in the direction indicated by an arrow e. member 61 a to form a color toner image holds a color toner. The member has, in addition to the foregoing, a transfer belt A transferring blade 64a as transferring means transfers the cleaning member 79, a belt driven roller 81, and a belt static color toner image formed on the Surface of the photosensitive 40 eliminator 82, and a pair of resist rollers 83 transports the member 61a onto the surface of a transfer material (recording transfer material in a transfer material holder to the transfer material) transported by a belt-like transfer material bearing material bearing member 68. Contact transferring means member 68. The transferring blade 64a can contact with the capable of directly applying a transfer bias by bringing a back surface of the transfer material bearing member 68 to roller-like transfer roller into contact with the back surface apply a transfer bias. 45 side of the transfer material bearing member 68 can also be In the first image-forming unit Pa, after the photosensitive used as transferring means instead of the transferring blade member 61 a has been Subjected to uniform primary charging 64a contacting with the back surface side of the transfer by the charging roller 62a, the electrostatic latent image is material bearing member 68. formed on the photosensitive member by the exposure light Further, generally used non-contact transferring means 67a from the exposing device, and the electrostatic latent 50 placed on the back surface side of the transfer material bear image is developed with the color toner by the developing ing member 68 in a non-contact manner to perform transfer device 63a. The developed toner image is transferred onto the by applying a transfer bias can also be used instead of the surface of the transfer material by applying the transfer bias above contact transferring means. from the transferring blade 64a contacting with the back The flow of a replenishing developer in an image-forming surface side of the belt-like transfer material bearing member 55 68 for bearing and transporting the transfer material at a first apparatus using the developer will be described with refer transfer portion (position at which the photosensitive member ence to FIG. 6. Toner in a developing device 102 is consumed and the transfer material contact with each other). by the development of an electrostatic latent image on a When a toner/magnetic carrier (T/C) ratio reduces as a photosensitive member with the toner. A toner concentration result of the consumption of the toner in the development, the 60 detecting sensor (not shown) detects the reduction of the toner reduction is detected by a toner concentration detecting sen in the developing device, whereby the developing device 102 sor 85 for measuring a change in permeability of the devel is fed with the replenishing developer from a replenishing oper by utilizing the inductance of a coil, and the developing developer storing container 101. An excess magnetic carrier device is replenished with a replenishing developer from a in the developing device moves toward a developer collecting replenishing developer container 65a in accordance with the 65 container 104. It should be noted that the developer collecting toner consumption. It should be noted that the toner concen container 104 may collect the toner collected by a cleaning tration detecting sensor 85 has the coil (not shown) in itself. unit 103 together. US 8,114,562 B2 27 28 Preliminary mixing was sufficiently performed with a Hen 30 Yellow Toner 1 was obtained in the same manner as in the schel mixer in accordance with the above formulation. The production example of Magenta Toner 1 in accordance with resultant was melted and kneaded with a biaxial extruding the above formulation. Table 2 shows the physical property kneader so that the temperature of the kneaded product was values of Yellow Toner 1. 150° C. After having been cooled, the resultant was coarsely Production of Yellow Toners 2 to 7 pulverized with a hammer mill into particles each having a 35 Yellow Toners 2 to 7 were each produced in the same particle diameter of about 1 to 2 mm. After that, the particles manner as in the above production of Yellow Toner 1 except were pulverized with the hammer mill with its hammer shape that a compounding ratio among Resin A, the refined paraffin changed, and coarse particles were removed with a mesh, wax, the yellow master batch, and the aluminum compound whereby coarsely pulverized products each having a particle of di-t-butylsalicylic acid was changed as shown in Table 3. diameter of about 0.3 mm were produced. Next, the coarsely 40 Table 2 shows the physical property values of Yellow Toners pulverized products were formed into moderately pulverized 2 to 7. products each having a particle diameter of about 11 Lim with Production of Cyan Toner 1 a Turbo mill (RS rotor/SNB liner) manufactured by Turbo Kogyo Co., Ltd. Further, the moderately pulverized products were pulverized with a Turbo mill (RSS rotor/SNNB liner) 45 Packed bulk True Magnetic Carrier 2 was obtained in the same manner as in Specific density density the production example of Magnetic Carrier 1 except that: the resistance p1 p2 magnetic component particles B were used instead of the Core particles (S2 cm) (g/cm) (g/cm) p1.?p2 magnetic component particles A.; and, in the resin penetration Magnetic component 5.2 x 10 2.0 4.9 O41 step of the production example of Magnetic Carrier 1, the particles C of carrier resin liquid 1 was caused to penetrate so that the mass of the Magnetic component 2.1 x 10 1.7 4.7 O.36 silicone resin accounted for 20 mass % of the mass of the particles D of carrier 10 Magnetic component 4.8 x 107 1.6 4.8 O.33 magnetic component particles. Table 5 shows the physical particles E of carrier property values of Magnetic Carrier 2 obtained here. Magnetic component 7.3 x 107 0.7 4.6 O.15 particles F of carrier Magnetic component 4.2 x 10 2.5 4.9 O.S1 Production Example of Magnetic Carrier 3 particles G of carrier 15 Magnetic component 8.2 x 10 1.8 S.O O.36 Magnetic Carrier 3 was obtained in the same manner as in particles H of carrier Magnetic component 7.4x 10 1.7 4.9 O.35 the production example of Magnetic Carrier 1 except that: the particles I of carrier magnetic component particles C were used instead of the Magnetic component 4.2 x 10 4.0 7.3 0.55 magnetic component particles A.; and, in the resin penetration particles J of carrier step of the production example of Magnetic Carrier 1, the resin liquid 1 was caused to penetrate so that the mass of the silicone resin accounted for 5 mass % of the mass of the Production Example of Magnetic Carrier 1 magnetic component particles. Table 5 shows the physical property values of Magnetic Carrier 3 obtained here. 25 <1. Preparation of Resin Liquid Production Examples of Magnetic Carriers 4, 5, and 10 Straight silicone resin (KR255 manufactured by Shin- 20.0 mass % Magnetic Carriers 4, 5, and 10 were each obtained in the Etsu Chemical Co., Ltd.) 30 same manner as in the production example of Magnetic Car Y-aminopropyltriethoxysilane 2.0 mass % Xylene 78.0 mass % rier 1 except that one of the magnetic component particles D. E. and H were used instead of the magnetic component par ticles A. Table 5 shows the physical property values of Mag The above three kinds of materials were mixed, whereby a netic Carriers 4, 5, and 10 obtained here. resin liquid 1 was obtained. 35 <2. Resin Penetration Step> Production Example of Magnetic Carrier 6 The resin liquid 1 was caused to penetrate into the pores of the magnetic component particles A So that the mass of the <1. Step of Preparing Resin Liquid silicone resin accounted for 10 mass % of the mass of the magnetic component particles A, and the pores of the mag 40 netic component particles A were filled with the resin. The Polymethyl methacrylate (Mw = 58,000) 1.5 mass % pores were filled with the resin by using a universal mixing Toluene 98.5 mass 9% stirrer (product name NDMV: Fuji Paudal Co., Ltd.) at a degree of vacuum of 50 kPa while the particles were heated to 70° C. The resin liquid 1 was charged in three portions at 0 45 The above materials were mixed, whereby a resin liquid 2 minute, 10 minutes, and 20 minutes. After the filling, the was obtained. particles were stirred for 1 hour. <2. Resin Penetration Step <3. Drying Step The resin liquid 2 was caused to penetrate into the pores of the magnetic component particles A So that the mass of the Xylene was removed by using a universal mixing stirrer 50 (product name NDMV: Fuji Paudal Co., Ltd) at a degree of polymethyl methacrylate accounted for 4 mass % of the mass vacuum of 5 kPa while the particles were heated at 100° C. for of the magnetic component particles A, and the pores of the 5 hours. magnetic component particles A were filled with the resin. <4. Curing Step The pores were filled with the resin by using a universal 55 mixing stirrer (product name NDMV; Fuji Paudal Co., Ltd.) The resultant particles were heated at 200°C. for 3 hours so at a degree of vacuum of 50 kPa while the particles were that the resin was cured. heated to 60° C. The resin liquid 2 was charged in three <5. Screening Step> portions at 0 minute, 10 minutes, and 20 minutes. After the The resultant particles were screened with a sieve having filling, the particles were stirred for 1 hour. an aperture of 75um by using a sieve shaker (300MM-2 type, 60 <3. Drying Step> TSUTSUI SCIENTIFIC INSTRUMENTS CO., LTD.), Toluene was removed by using a universal mixing stirrer whereby Magnetic Carrier 1 was obtained. It should be noted (product name NDMV: Fuji Paudal Co., Ltd.) at a degree of that Magnetic Carrier 1 obtained here had the porous mag vacuum of 5 kPa while the particles were heated at 100° C. for netic core particles the surface of each of which was coated 5 hours. with the resin loaded into the pores of the particles. Table 5 65 <4. Curing Steps shows the physical property values of Magnetic Carrier 1 The resultant particles were heated at 220°C. for 3 hours so obtained here. that the resin was cured. US 8,114,562 B2 49 50 <5. Screening Step> SiCl, were added to the mixture while the mixture was stirred. The resultant particles were screened with a sieve having Further, the resultant mixture was stirred for 30 minutes, and an aperture of 75um by using a sieve shaker (300MM-2 type, was then subjected to a condensation reaction at 60° C. for 1 TSUTSUI SCIENTIFIC INSTRUMENTS CO., LTD.), hour. After that, the resultant siloxane was sufficiently whereby resin-containing Magnetic Particle 6 was obtained. 5 washed with water and dissolved in a toluene-methyl ethyl ketone-butanol mixed solvent, whereby a silicone varnish The resin-containing Magnetic Particle 6 was named Mag having a solid content of 10% was prepared. 2.0 parts by mass netic Carrier 6. It should be noted that Magnetic Carrier 6 of ion-exchanged water, 2.0 parts by mass of the following obtained here had the porous magnetic core particles the curing agent (3), and 3.0 parts by mass of the following surface of each of which was coated with the resin loaded into aminosilane coupling agent (4) were simultaneously added to the pores of the particles. Table 5 shows the physical property 10 the silicone varnish with respect to 100 parts by mass of a values of Magnetic Carrier 6 obtained here. siloxane Solid content, whereby a carrier coat Solution was produced. Production Example of Magnetic Carrier 7 Magnetic Carrier 1 obtained in the production example of 15 Chem 2 Magnetic Carrier 1 was pulverized with a collision type air (3) pulverizer, and was then classified with an air classifier (El CH3 bow Jet Lab EJ-L3, manufactured by Nittetsu Mining Co., / Ltd.), whereby Magnetic Carrier 7 was obtained. Table 5 CH-Si-HO-N=C shows the physical property values of Magnetic Carrier 7 CH2115 3 obtained here. Chem3) (4) Production Example of Magnetic Carrier8 H HN-CH- N-CH-Si-O-OCH3) Magnetic Carrier8 was obtained in the same manner as in 25 the production example of Magnetic Carrier 2 except that the magnetic component particles B of a carrier were changed to The above carrier coat solution was applied to the above the magnetic component particles F of a carrier. Table 5 magnetic component particles J with a coater (manufactured shows the physical property values of Magnetic Carrier8 by OKADA SEIKO CO.,LTD.: Spira Coater) so that a resin 30 coat amount was 1.0 part by mass with respect to 100 parts by obtained here. mass of the particles, whereby Magnetic Carrier 13 coated with a silicone resin was obtained. Table 5 shows the physical Production Example of Magnetic Carrier 9 property values of Magnetic Carrier 13 obtained here. Magnetic Carrier 9 was obtained in the same manner as in the production example of Magnetic Carrier 3 except that the 35 TABLE 5 magnetic component particles C of a carrier were changed to 50% particle the magnetic component particles G of a carrier. Table 5 diameter on shows the physical property values of Magnetic Carrier 9 Magnetic volume basis obtained here. carrier P2P1 (D50) Carrier core 40 Carrier 1 O.91 38 Magnetic componen Production Example of Magnetic Carrier 11 particles A of carrier Carrier 2 O.87 44 Magnetic componen particles B of carrier Magnetic Carrier 11 was obtained in the same manner as in Carrier 3 O.9S 51 Magnetic componen the production example of Magnetic Carrier 6 except that, in particles C of carrier the resin penetration step of the example, polymethyl meth 45 Carrier 4 O.9 43 Magnetic componen particles D of carrier acrylate was used so as to account for 3 mass % of the mass of Carrier 5 O.85 65 Magnetic componen the magnetic carrier core (the magnetic component particles particles E of carrier A). Table 5 shows the physical property values of Magnetic Carrier 6 0.72 40 Magnetic componen Carrier 11 obtained here. particles A of carrier 50 Carrier 7 1.02 49 Magnetic componen particles A of carrier Production Example of Magnetic Carrier 12 Carrier8 0.72 44 Magnetic componen particles F of carrier Magnetic Carrier 12" was obtained in the same manner as in Carrier 9 O.96 S4 Magnetic componen the production example of Magnetic Carrier 2 except that the particles G of carrier 55 Carrier 10 O.82 8O Magnetic componen magnetic component particles B of a carrier were changed to particles H of carrier the magnetic component particles I of a carrier. Magnetic Carrier 11 O.67 37 Magnetic componen Carrier 12 and Magnetic Carrier 1 were mixed at a mass ratio particles A of carrier of 20:80, whereby Magnetic Carrier 12 was obtained. Table 5 Carrier 12 1.32 32 Magnetic componen particles A, I of shows the physical property values of Magnetic Carrier 12 carrier obtained here. 60 Carrier 13 O.92 44 Magnetic componen particles J of carrier Production Example of Magnetic Carrier 13 20 parts by mass of toluene, 20 parts by mass ofbutanol. 20 Examples 1 to 38 and Comparative Examples 1 to 12 parts by mass of water, and 40 parts by mass of ice were 65 loaded into a four-necked flask, and 40 parts by mass of a Starting developers and replenishing developers were pro mixture of 15 moles of CHSiCls and 10 moles of (CH) duced by combining the above magnetic carriers and the US 8,114,562 B2 51 52 above toners as shown in Table 6. Each of the developers was A: Less than 0.5% (good) charged into a reconstructed device of a full-color copying B: 0.5% or more and less than 1.0% machine CLC5000 manufactured by Canon Inc. (the contents C: 1.0% or more and less than 2.0% of the reconstruction will be described later), and was evalu D: 2.0% or more (bad) ated for various items. It should be noted that the starting 5 Toner Carrier Q/m2 force Toner Carrier Example 1 Magenta Carrier 1 61 13 Magenta Carrier 1 Toner 2 Toner 2 Example 2 Magenta Carrier 1 61 13 Magenta Carrier 1 Toner 3 Toner 3 US 8,114,562 B2 55 56 TABLE 6-continued Starting developer Replenishing Adhesive developer Carrier force Carrier Exam Carrier 60 3 Carrier Exam Carrier 65 4 Carrier Exam Carrier 67 Carrier Exam Carrier 65 Carrier Comp Carrier 60 Carrier Exam ble 1 Comp Carrier 68 Carrier Exam ble 2 Exam ble 7 Carrier 72 Carrier Exam Carrier 75 Carrier Exam Carrier 75 Carrier Exam Carrier 78 Carrier Exam Carrier 78 Carrier Comp Carrier 72 Carrier Exam Comp Carrier 77 Carrier Exam Exam Carrier 68 Carrier Exam Carrier 62 Carrier Exam ble 14 Carrier 70 Carrier Exam ble 15 Toner 5 Carrier 75 Carrier Exam ble 16 Toner 6 Carrier 74 Carrier Exam ble 17 Toner 7 Carrier 95 Carrier Exam ble 18 Toner 8 Carrier 68 Carrier Exam ble 19 Toner 9 Carrier 69 Carrier Exam ble 20 Toner Carrier 65 Exam ble 21 Toner Carrier 2 65 Exam ble 22 Toner Carrier 3 65 Exam ble 23 Toner Carrier 4 65 Exam ble 24 Toner Carrier 5 65 Exam ble 25 Toner Carrier 6 65 Exam ble 26 Toner Carrier 7 65 Exam ble 27 Toner Carrier8 65 Exam ble 28 Toner Carrier 9 65 Exam ble 29 Toner Carrier 65 10 Exam ble 30 Toner Carrier 65 11 Exam ble 31 Toner Carrier 65 12 Exam ble 32 Toner Carrier 62 12 Exam ble 33 Toner Carrier 62 12 Exam ble 34 Toner Carrier 65 12 Exam ble 35 Toner Carrier 61 12 US 8,114,562 B2 57 58 TABLE 6-continued Starting developer Replenishing Adhesive developer Toner Carrier Q/m2 force Toner Carrier Example 36 Cyan Toner Carrier 116 5 Cyan 16 2 Toner 16 Example 37 Cyan Toner Carrier 55 2 Cyan 17 2 Toner 17 Example 38 Cyan Toner Carrier 63 2 Cyan 21 3 Toner 21 Comparative Cyan Toner 1 Carrier 62 2 Cyan Example 5 3 Toner 1 Comparative Cyan Toner Carrier 55 2 Cyan Example 6 22 3 Toner 22 Comparative Cyan Toner Carrier 47 O Cyan Example 7 18 3 Toner 18 Comparative Cyan Toner Carrier 125 8 Cyan Example 8 19 3 Toner 19 Comparative Cyan Toner Carrier 49 O Cyan Example 9 2O 3 Toner 20 Comparative Cyan Toner Carrier 65 4 Cyan Example 10 23 3 Toner 23 Comparative Cyan Toner Carrier 65 4 Cyan Example 11 24 3 Toner 24 Comparative Cyan Toner Carrier 60 2 Cyan Example 12 25 3 Toner 25 *1 An adhesive force (F50) by a centrifugal method when the absolute value for the triboelectric charge quantity oftoner is 50 mC/kg *The absolute value for the triboelectric charge quantity oftoner measured by a two-component method using the toner and a magnetic carrier TABLE 7 Lowest Laid-on fixation level Image Transferring temperature Carrier Dot Cleaning (mg/cm. AE void performance o C. Fogging adhesion reproducibility performance Example 1 O49 A. C A. 55 A. A. A. A. Example 2 O41 A. B A. 50 A. A. A. A. Example 3 O.30 B A. A. 40 A. A. A. A. Example 4 O.25 A. A. A. 40 A. A. A. A. Example 5 O.21 B A. A. 35 B A. B A. Example 6 O.25 C A. A. 35 C A. B A. Comparative O.S8 B D C 55 A. A. C A. Example 1 Comparative O.25 D A. A. 35 D A. D A. Example 2 Example 7 0.44 A. C A. 60 A. A. A. A. Example 8 O.35 A. B A. 55 A. A. A. A. Example 9 O.26 B A. A. 40 B A. A. A. X8. It O.20 A. A. A. 40 B A. A. A. O Example O.18 B A. A. 35 C A. B A. 1 Comparative O.S1 B D C 60 A. A. C A. Example 3 Comparative O.18 C A. A. 35 D A. C A. Example 4 Example O45 B C A. 60 A. A. A. A. 2 Example 0.37 A. B A. 55 A. A. A. A. 3 Example O.28 A. A. A. 40 A. A. B A. 4 Example O.28 A. A. C 40 C A. B A. 5 Example O.28 A. A. B 40 A. A. A. A. 6 Example O.28 B A. A. 40 C A. B A. 7 Example O.28 B A. B 40 B A. B A. 8 Example O.28 B A. C 40 C A. B A. 9 US 8,114,562 B2 59 60 TABLE 7-continued Lowest Laid-on fixation level Image Transferring temperature Carrier Dot Cleaning (mg/cm. AE void performance o C. Fogging adhesion reproducibility performance X8. It O.23 C A. B 40 B A. C A. 2O Example O.23 B A. B 40 B C C A. 21 Example O.23 C A. B 40 C A. C A. 22 Example O.23 B A. B 40 B C C A. 23 Example O.23 C A. B 40 B A. C A. 24 Example O.23 C A. B 40 B A. C A. 25 Example O.22 C A. B 40 B A. C A. 26 Example O.22 C A. B 40 B C C A. 27 Example O.22 B A. B 40 C B C A. 28 Example O.22 B A. B 40 B A. C A. 29 Example O.22 B A. B 40 B A. C A. 30 Example O.22 C A. B 40 C A. C A. 31 Example O.20 C A. B 40 C A. C A. 32 Example O.20 C A. B 40 C A. C B 33 Example O.20 C A. B 40 C A. C C 34 Example O.20 C A. C 40 C A. C B 35 Example O.20 C A. C 40 C A. C A. 36 Example O.20 C A. C 40 C A. C A. 37 Example O.24 C A. B 35 C A. C A. 38 Comparative 0.55 B D C 65 C A. C A. Example 5 Comparative O.25 D A. B 35 C A. C A. Example 6 Comparative O.20 D A. B 40 C A. C C Example 7 Comparative Example 8 Comparative O.20 D A. B 35 C A. C A. Example 9 Comparative O60 C D D 70 C A. D A. X8. It O Comparative O.68 B D D 8O C A. D A. Example 1 Comparative Example 2 In Comparative Example 8, a charge quantity was so large ss component developer having the constitution of Example 12 that a toner amount needed for achieving a required density were each loaded into the above-mentioned reconstructed could not be used for development. In Comparative Example device of a full-color copying machine CLC5000 manufac 12, coloring power was so low that there was a need for using tured by Canon Inc. Then, a full-color image was formed a large amount of toner for development, but a needed toner under Such a toner laid-on level condition that the monochro amount could not be used for development, and no Subse 60 matic Solid image density of each color was 1.5. As a result, a quent evaluation could be performed. good full-color image was obtained. It should be noted that, in this example, the full-color image was formed without the use Example 39 of any black developer, a good full-color image can be simi larly obtained even when a black developer is used. The magenta two-component developer having the consti 65 While the present invention has been described with refer tution of Example 1, the yellow two-component developer ence to exemplary embodiments, it is to be understood that having the constitution of Example 7, and the cyan two the invention is not limited to the disclosed exemplary US 8,114,562 B2 61 62 embodiments. The scope of the following claims is to be um or more and 200.00 um or less has an average circularity accorded the broadest interpretation so as to encompass all of 0.945 or more and 0.970 or less. Such modifications and equivalent structures and functions. 5. A two-component developer according to claim 1, This application claims the benefit of Japanese Patent wherein the external additive contains inorganic fine par Application No. 2007-024381, filed Feb. 2, 2007, which is 5 ticles, and the inorganic fine particles have a number average hereby incorporated by reference herein in its entirety. particle diameter of 80 nm or more and 300 nm or less. What is claimed is: 6. A two-component developer according to claim 5. 1. A two-component developer, comprising: wherein the inorganic fine particles each comprise spherical a yellow toner having yellow toner particles each having at silica produced by a sol-gel method. least a binder resin and a colorant, and an external addi 10 7. A replenishing developer for use in a two-component tive; and developing method including: performing development a magnetic carrier, while replenishing a developing device with the replenishing (a) wherein the yellow toner has the following character developer, and discharging an excess magnetic carrier in the istics: developing device from the developing device, comprising: (i) when a concentration of the yellow toner in a solution of 15 a yellow toner having yellow toner particles each having at the yellow toner in chloroform is represented by Cy least a binder resin and a colorant, and an external addi (mg/ml) and an absorbance of the Solution at a wave tive; and length of 422 nm is represented by A422, a relationship a magnetic carrier, between Cy and A422 satisfies the following expression the replenishing developer being a two-component devel (5) oper containing the yellow toner at a mass ratio of 2 parts 6.00