(12) United States Patent (10) Patent No.: US 6,602,594 B2 Miyata Et Al

USOO66O2594B2 (12) United States Patent (10) Patent No.: US 6,602,594 B2 Miyata et al. (45) Date of Patent: Aug. 5, 2003

(54) IRREVERSIBLE HEAT-SENSITIVE 4,756,758. A 7/1988 Lent et al...... 106/22 COMPOSITION 4,797.243 A * 1/1989 Wolbrom ...... 264/126 4,931,420 A 6/1990 Asano et al...... 503/205 (75) Inventors: Sachie Miyata, Kawagoe (JP); Hiromichi Mizusawa, Hannou (JP); FOREIGN PATENT DOCUMENTS Daisuke Harumoto, Sakado (JP) WO WO 98/02314 * 1/1998 (73) Assignee: Nichiyu Giken Kogyo Co., Ltd. (JP) (*) Notice: Subject to any disclaimer, the term of this * cited by examiner patent is extended or adjusted under 35 U.S.C. 154(b) by 122 days. Primary Examiner B. Hamilton Hess (74) Attorney, Agent, or Firm-Parkhurst & Wendel, L.L.P. (21) Appl. No.: 09/839,265 (57) ABSTRACT (22) Filed: Apr. 23, 2001 (65) Prior Publication Data An irreversible heat-Sensitive composition comprises a mix ture of a granular or powdery heat-fusible Substance having US 2001/0044014 A1 Nov. 22, 2001 a melting point corresponding to a temperature to be (30) Foreign Application Priority Data recorded and a granular or powdery dyestuff diffusible into Apr. 25, 2000 (JP) ...... 2000-124431 the fused heat-fusible Substance through dispersion or dis Jan. 29, 2001 (JP) ...... 2001-020557 Solution. A heat-Sensitive ink comprises the irreversible Jan. 29, 2001 (JP) ...... 2001-020558 heat-Sensitive composition and an ink vehicle capable of (51) Int. Cl." ...... B41M 5/30; B41M 5/36 diffusing the fused heat-fusible substance therein. A heat (52) U.S. Cl...... 428/323; 106/31.29; 106/31.33; Sensitive ink according to another embodiment comprises 428/206; 428/207; 428/321.3; 428/913 (58) Field of Search ...... 428/195, 207, microcapsules, which encapsulate the irreversible heat 428/484, 488.1,913,914, 206, 323,321.3; Sensitive composition. A heat-Sensitive indicator comprises 106/31.13, 31.27, 31.29, 31.33 a Substrate provided thereon with a printed heat-Sensitive ink, the heat-Sensitive ink being one of these heat-Sensitive (56) References Cited inkS. U.S. PATENT DOCUMENTS 4,050,945. A 9/1977 Suzuki ...... 106/21 12 Claims, No Drawings US 6,602,594 B2 1 2 RREVERSIBLE HEAT-SENSITIVE SUMMARY OF THE INVENTION COMPOSITION Accordingly, it is a first object of the present invention to provide a heat-Sensitive composition, which undergoes an BACKGROUND OF THE INVENTION irreversible color change responding to a temperature The present invention relates to a heat-Sensitive ink change, which permits the use of a wide variety of dyestuffs, comprising a heat-Sensitive composition, which can undergo which can be used in printing irrespective of the shape of a an irreversible color tone change at a predetermined tem target to be printed, which can be mass-produced and perature to thus permit the recording of whether a specific permits the reduction of the production cost thereof and Substance is exposed to a temperature higher than a prede which allows the Systematization of temperatures for indi termined level or not, as well as a heat-Sensitive indicator cation or detection. using the Same. The irreversible heat-Sensitive composition according to There have been known products, for instance, processed the present invention developed to achieve the first object of food products, which should be heat-treated at a temperature the present invention comprises a mixture of a granular (or higher than a specific level during the manufacture of the granular) or powdery heat-fusible Substance having a melt Same. There have also been known Some products or articles 15 ing point corresponding to a temperature to be recorded and Such as products for medical use and food products, which a granular or powdery dyestuff diffusible into the fused are deteriorated, decomposed and/or putrefied, if they are heat-fusible Substance through dispersion or dissolution. exposed to a temperature higher than a specific one. In It is a Second object of the present invention to provide a addition, there have likewise been known Such products as heat-Sensitive ink, which can indicate, with high precision, electric equipments and electric parts, which get out of whether it is exposed to a temperature exceeding a prede order, are broken and/or possibly cause a fire due to overheat termined level or it has a desired temperature history or not, in case of, for instance, a motor. through a clear color tone change. As a means for detecting whether a particular product The heat-Sensitive ink according to the present invention experiences or is exposed to a temperature exceeding a 25 developed to accomplish the Second object of the present predetermined level or not, there have conventionally been invention comprises the foregoing irreversible heat-Sensitive used, for instance, temperature-indicating materials capable composition and an ink vehicle capable of diffusing the of changing their color tone upon exposure thereof to Such fused heat-fusible Substance therein. a predetermined temperature. According to another embodiment of the heat-Sensitive AS Such temperature-indicating materials, there have been ink of the present invention comprises microcapsules in known those comprising heat-fusible Substances and acid which the foregoing irreversible heat-Sensitive composition base indicators, specific examples of which are disclosed in, is enclosed or encapsulated. for instance, Japanese Patent Provisional Publication No. It is a third object of the present invention to provide a Sho 61-12783 and Japanese Patent Provisional Publication heat-Sensitive indicator, which can indicate, with high No. Sho 61-14284. The temperature-indicating materials of 35 precision, whether it is exposed to a temperature exceeding this type are reversible temperature indicators since they a predetermined level or it has a desired temperature history undergo color change upon heating and the color tone or not, through a clear color tone change which the color thereof is returned back to the original one when they are change itself could be preserved, and could easily be mass cooled. If a temperature-indication material of this type is produced. used, whether a product is exposed to a temperature exceed 40 The heat-Sensitive indicator according to the present ing a predetermined level or not can be confirmed by invention developed to achieve the third object of the monitoring the color tone change of the material during invention comprises a Substrate, which the foregoing heat heating. However, if the color tone change of Such a material Sensitive ink is printed on. is not monitored, it is impossible to confirm if a product DETAILED EXPLANATION OF THE experiences a temperature exceeding a predetermined level 45 once the time elapses and the temperature of the product is INVENTION reduced. Moreover, it is also impossible to record and The irreversible heat-Sensitive composition according to preserve Such a temperature history of the product. the present invention comprises a mixture of a granular or In addition, Japanese Patent Provisional Publication No. powdery heat-fusible Substance with a granular or powdery Hei 10-239172 discloses a device for monitoring the upper 50 dyestuff. temperature limit, which comprises a thin film of pigmented The irreversible heat-sensitive composition preferably Solid paraffin and a thin Solid paraffin film having the same comprises 0.001 to 100 parts by weight of the granular or quality and deposited on the former. This device is one powdery dyestuff per 100 parts by weight of the granular or prepared by forming a thin film of paraffin previously powdery heat-fusible Substance. pigmented and then depositing a thin film of non-pigmented 55 The heat-fusible Substance is a component, which deter paraffin on the surface of the former and should have a mines the color change-temperature of the irreversible heat predetermined shape. This device is designed in Such a Sensitive composition and a Substance, which has, under manner that, when the device is exposed to a temperature ordinary pressure, a melting point corresponding to the exceeding a predetermined one, the fused upper layer or temperature to be recorded and which can be fused when non-pigmented paraffin thin film is admixed with the lower 60 heated to a temperature higher than the melting point and layer or the pigmented paraffin thin film likewise in the fused undergo a change in State from a granular or powdery State State to thus develop a color tone apparently different from to a liquid State. The heat-fusible Substance Suitably used that observed prior to the fusion. herein is at least one member Selected from the group Moreover, Japanese Utility Model Application Publica consisting of fatty acid derivatives, alcohol derivatives, ether tion No. Sho 46-28235 discloses an irreversible label. This 65 derivatives, aldehyde derivatives, ketone derivatives, amine label should be produced as a three-dimensional Structure derivatives, amide derivatives, nitrile derivatives, hydrocar and therefore, the application thereof is quite limited. bon derivatives, thiol derivatives and Sulfide derivatives. US 6,602,594 B2 3 4 Specific examples of fatty acid derivatives are myristic diffuse into the fused heat-fusible substance through disper acid, palmitic acid, adipic acid, octanoic acid, tricosanoic Sion or dissolution. Alternatively, the dyestuff may likewise acid, tetratriacontanoic acid, 2,3-dimethyl nonanoic acid, be one Such that the Surface of the dyestuff granule or 23-methyl tetracosanoic acid, 2-hexenoic acid, brassidic powder is wetted with the fused heat-fusible substance and acid, 2-methyl-2-dodecenoic acid, B-eleoStearic acid, changed to a wet color. The dyestuff may be selected from behenolic acid, cis-9,10-methylene octadecanoic acid, wide variety of dyestuffs, for instance, dyes Such as direct chaulmoogric acid, n-dodecyl 3,3'-thiodipropionate, dyes, acid dyes, basic dyes, disperse dyes, reactive dyestuffs, trilaurin, palmitic acid anilide, Stearic acid amide, Zinc oil-Soluble dyes, vat dyes, mordant dyes, azo dyes and Stearate, Salicylic acid anilide, N-acetyl-L-glutamic acid, Sulfide dyes, pigments Such as organic pigments and inor cap roic acid-f-naphthylamide, enanthic acid ganic pigments, and pigmented Substances. These dyestuffs phenylhydrazide, p-chlorophenacyl arachionate, choleste may be used alone or in any combination of at least two of ryll formate, 1-aceto-2,3-distearin, pentadecyl thiolaurate, them. Stearic acid chloride, palmitic acid anhydride, Stearic acid Specific examples of dyes include C.I. Direct Orange 39, acetic acid anhydride, Succinic acid, Sebacic acid benzyl C.I. Direct Brown 2, C.I. Acid Yellow 73, C.I. Acid Red 52, ammonium Salt, 2-bromoValeric acid, methyl C-SulfoStearic 15 C.I. Acid Violet 49, C.I. Basic Yellow 11, C.I. Basic Red 38, acid Sodium Salt, and 2-fluoroarachic acid. Cathilon Red GTLH, Cathilon Red 4GH, Cathilon Red Specific examples of alcohol derivatives are octadecyl 7BN11 and Cathilon Red SGLH (available from Hodogaya alcohol, cholesterin, D-mannitol, galactitol, hepta Chemical Co., Ltd.); C.I. Mordant Red 7, C.I. Mordant triacontanol, hexadecan-2-ol, 1-trans-2-octadecenol, Black 38, C.I. Azoic Blue 9, C.I. Azoic Diazo Component f-eleoStearyl alcohol, cycloeicosanol, d(+)cellobiose, p.p'- 11, C.I. Sulfur Black 1, C.I. Sulfur Red 5, C.I. Vat Green 9, biphenol, riboflavin, 4-chloro-2-methylphenol and 2-bromo C.I. Vat Violet 2, C.I. Disperse Blue 3 and Discharge Red BB 1-indanol. (available from Mitsui Toatsu Dyes Co., Ltd.); C.I. Reactive Specific examples of ether derivatives include dihexade Blue 19, C.I. Reactive Blue 15 and Remazol Br Blue R-KN cyl ether, dioctadecyl ether, cytidine, adenosine, Sodium (available from Mitsubishi Chemical Industries, Ltd.); C.I. phenoxyacetate, 1,3-bis (4-hydroxyphenoxy)-benzene and 25 Solvent Orange 2, C.I. Solvent Blue 25, C.I. Acid Green 1, aluminium triethoxide. Flavianic Acid Disodium Salt and Primuline Sulfonic Acid. Specific examples of aldehyde derivatives are Stearin Specific examples of organic pigments are 4,10 aldehyde, paralauryl aldehyde, parastearin aldehyde, dibromoanthanthrone, dibenzoanthrone, cochineal lake, C.I. naphthoaldehyde, p-chlorobenzaldehyde, phthalaldehyde Pigment Yellow 1, C.I. Pigment Red 38, C.I. Pigment Blue and 4-nitrobenzaldehyde. 15, C.I. Pigment Red 209, C.I. Pigment Yellow 109, C.I. Pigment Green 10, C.I. Basic Red 1-Lake, C.I. Acid Red Specific examples of ketone derivatives are Stearone, 87-Lake, C.I. Pigment Blue 6, C.I. Pigment Red 179, C.I. do co Son-2- one, phenyl he pta de cyl ketone, Pigment Red 88, Alizarin Lake, C.I. Pigment Violet 23, C.I. cyclononadecane, Vinyl heptadecyl ketone, 4,4-bisdimethyl Pigment Green 8, C.I. Pigment Red 53, C.I. Pigment Yellow aminobenzophenone, bis (2,4-pentanedionite) calcium and 35 1-chloroanthraquinone. 23-Lake, tannic acid-gallic acid-iron lake, C.I. Pigment Specific examples of amine derivatives include Yellow 34 and C.I. Pigment Yellow 35. In this connection, tricosylamine, dioctadecylamine, N,N-dimethyl octylamine, the foregoing term “C.I.' is an abbreviation of “color index”. heptade came thyleneimine, naphthylamine, ethyl Specific examples of inorganic pigments are kaolin, Prus sian blue, Strontium Sulfate, titanium dioxide, aluminum p-aminobenzoate, O-trithiourea, Sulfamethazine, guanidine 40 nitrate, p-chloroaniline and propylamine hydrochloride. hydroxide, calcium Silicate and carbon black. Specific examples of amide derivatives are hexylamide, The dyestuff preferably has a particle Size ranging from octacosylamide, N-methyl dodecylamide, N-methyl 0.001 um to 5 mm. heptacosylamide, C.-cyanoacetamide, Salicylamide, In the irreversible heat-Sensitive composition, the granu dicyandiamide, 2-nitrobenzamide and N-bromoacetamide. 45 lar or powdery heat-fusible Substance and the granular or Specific examples of nitrile derivatives include pentade powdery dyestuff are in a mixed State, the dyestuff is covered cane nitrile, margaro nitrile, 2-naphthonitrile, up with the heat-fusible Substance and the granular or o-nitrophenoxy acetic acid, 3-bromobenzonitrile, powdery heat-fusible Substance is fused, while the granular 3-cyanopyridine and 4-cyanophenol. or powdery dyestuff is dispersed or dissolved in or wetted 50 with the fused heat-fusible Substance to thus cause a color Specific examples of hydrocarbon derivatives are tone change when the temperature reaches or exceeds a hexadecane, 1-nonatriacontene, trans-n-2-octadecene, desired level. After the color tone change, it is never returned heXatriacontylbenzene, 2-methylnaphthalene, picene, cya back to the original color tone even if the composition is nuric chloride, 1-fluorononadecane, 1-chloroeicosane, 1-iodopentadecane, 1-bromoheptadecane and 1,2,4,5- cooled and the heat-fusible Substance is solidified. 55 To obtain this irreversible heat-Sensitive composition, a tetrakis (bromomethyl) benzene. heat-fusible Substance and a dyestuff are mixed together in Specific examples of thiol derivatives are pentadecane a desired mixing ratio, followed by pulverization of the thiol, eicosane thiol, 2-naphthalene thiol, 2-mercaptoethyl resulting mixture to a desired particle size, or the foregoing ether and 2-mitrobenzene Sulfenyl chloride. two components are separately pulverized to a desired Specific examples of Sulfide derivatives are 1,3-diatine, 60 particle size and then the pulverized components are mixed 2,11-dithia 3.3 paracyclophane, bis (4-hydroxy-3- together in a desired mixing ratio. methylphenyl) sulfide, 4,4-dipyridyl sulfide and 4-methyl The heat-Sensitive ink according to the present invention mercaptophenol. comprises the foregoing irreversible heat-Sensitive compo This heat-fusible Substance preferably has a particle Size Sition comprising a mixture of a granular or powdery ranging from 0.01 um to 5 mm. 65 heat-fusible Substance having a melting point corresponding The dyestuff is included in the irreversible heat-sensitive to a temperature to be recorded and a granular or powdery composition in the form of granules or powder and can dyestuff diffusible into the fused heat-fusible substance US 6,602,594 B2 S 6 through dispersion or dissolution; and an ink vehicle capable dyestuff present in the ink, but also the environmental of diffusing the fused heat-fusible substance therein. resistance of the ink. Moreover, in the preparation of the ink, The ink vehicle does not permit any dissolution or diffu vehicles and Solvents to be incorporated into the ink are not sion of the heat-fusible substance and the dyestuff at ordi restricted to those, which do not dissolve the heat-fusible nary temperature, but permits the diffusion of the fused Substance and the dyestuff and the resulting ink is excellent substance in which the dyestuff is dispersed or dissolved. in the printability and the Storage Stability after printing. The ink vehicle may be, for instance, acrylic resins, phenol The heat-Sensitive ink preferably comprises an ink vehicle resins, nylon, ethyl cellulose, hydroxymethyl cellulose, identical to those described above. The ink vehicle may be polyvinyl alcohol and carboxymethyl cellulose. The ink commercially available ones other than those listed above vehicle may likewise be any commercially available ink Such as Aqua Set Ink (the trade name of a product available vehicles such as PAS800 Medium (the trade name of a from Jujo Chemical industry Co., Ltd.), VAR-000 Medium product available from Jujo Chemical Industry Co., Ltd.) (the trade name of a product available from Teikoku Ink and High Set Mat Medium (the trade name of a product K.K.) and Ramistar R Medium (the trade name of a product available from Mino Group K.K.). available from Toyo Ink Mfg. Co., Ltd.). It is preferred that the heat-fusible substance be included 15 This heat-Sensitive ink may comprise a Solvent capable of in the heat-Sensitive ink in an amount ranging from 10 to dissolving the ink vehicle. This Solvent may be isopropyl 70% by weight. This is because if the amount thereof is less alcohol in addition to those listed above. than 10% by weight, the resulting color tone change is This heat-Sensitive ink can preferably be prepared as insufficient or indistinct, while if it exceeds 70% by weight, follows: First, microcapsules are prepared according to the the adhesive force of the resulting ink is too low to coat or interfacial polymerization method. More Specifically, a heat print a Substrate with the ink. fusible Substance and a dyestuff are dispersed or emulsified This heat-Sensitive ink may comprise a Solvent, which in a solvent which does not dissolve the heat-fusible Sub does not dissolve the heat-fusible substance and the dyestuff, stance and the dyestuff, but can dissolve a polymeric com but can dissolve the ink vehicle. Such a solvent may be, for pound for forming the Outer wall of the microcapsules using instance, water, ethanol, butanol, ethyl acetate, isoamyl 25 a device Such as a stirring machine, a disperser, a homog acetate, methyl ethyl ketone, methyl isobutyl ketone, Xylene, enizer or a mixer. Then an emulsifying-hardening agent is diethyl benzene, toluene, butyl cellosolve, ethyl cellosolve added to the resulting dispersion to thus form the outer wall and mineral Spirit. of the microcapsules and thereafter the resulting microcap This heat-Sensitive ink can be prepared by uniformly Sules are separated from the Solvent by, for instance, filtra kneading, in a kneader, the foregoing heat-fusible Substance tion to thus give desired microcapsules in which the heat and dyestuff, which are pulverized to a desired particle size, fusible Substance and the dyestuff are enclosed. Finally, an an ink vehicle and a Solvent. ink vehicle, a Solvent for ink vehicle and the resulting microcapsules are kneaded in a kneader to give a heat According to another embodiment of the heat-Sensitive Sensitive ink. ink of the present invention may comprise microcapsules 35 each of which encloses the foregoing irreversible heat In this respect, the heat-Sensitive ink may further com Sensitive composition comprising a mixture of a granular or prise a dispersant for improving the dispersibility of the powdery heat-fusible Substance having a melting point cor dyestuff and for making the color tone change of the ink responding to a temperature to be recorded and a granular or more distinct, Such as talc, magnesium carbonate and Silica. powdery dyestuff diffusible into the fused heat-fusible Sub 40 In order to make the color tone change more distinct, the stance through dispersion or dissolution. The microcapsules heat-Sensitive ink may optionally comprise at least one are unevenly distributed in the resulting ink. member Selected from the group consisting of dyes Such as direct dyes, acid dyes, basic dyes, disperse dyes, reactive The microcapsule is, for instance, a minute particle hav dyestuffs, oil-Soluble dyes, vat dyes, mordant dyes, azo dyes ing a uniform outer wall and having a size ranging from and Sulfide dyes, pigments Such as organic pigments and about 0.01 um to about 10 mm, which encloses the granular 45 inorganic pigments, which are auxiliary coloring agents or powdery dyestuff and heat-fusible substance. showing colors contrast to the color tone of the dyestuff. In the present invention, it is preferred that the outer wall Moreover, the heat-Sensitive ink may likewise comprise a of the microcapsule be formed from a polymer compound wax and/or a Surfactant for controlling the flowability and Selected from the group consisting of polyvinyl alcohol, 50 the drying characteristics of the ink. polystyrene, Silicone resins, epoxy resins, acrylic resins, The heat-Sensitive indicator according to the present urea resins, gelatin, methyl cellulose, polyurethane, waxes, invention comprises a Substrate and a printed layer of the gum arabic, dextrin, and nylon. foregoing heat-Sensitive ink, which is applied onto the Such microcapsules are, for instance, prepared by an Surface of the Substrate and comprises an irreversible heat interfacial polymerization method, an in-situ production 55 Sensitive composition, which is a mixture of a granular or method, a phase Separation method, a Suspension-in air powdery heat-fusible Substance having a melting point cor method, an electroStatic coalescence method, a spray coagul responding to a temperature to be recorded and a granular or lation method and a drying-in liquid method. powdery dyestuff diffusible into the fused heat-fusible Sub The microcapsules are preferably contained in the heat stance through dispersion or dissolution, and an ink vehicle sensitive ink in an amount ranging from 10 to 70% by 60 capable of diffusing the fused heat-fusible substance therein. weight. This is because if the amount thereof is less than According to another embodiment of the present 10% by weight, the color tone change of the resulting ink is invention, the heat-Sensitive indicator comprises a Substrate insufficient or indistinct, while if it exceeds 70% by weight, and a printed layer of the foregoing heat-Sensitive ink, which the adhesive force of the resulting ink is too low to coat or is applied onto the Surface of the Substrate and comprises print a Substrate with the ink. 65 microcapsules each of which encloses the irreversible heat The use of the microcapsules permits the improvement of Sensitive composition comprising a mixture of a granular or not only the stability of the heat-fusible substance and the powdery heat-fusible Substance having a melting point cor US 6,602,594 B2 7 8 responding to a temperature to be recorded and a granular or change, the color tone thereof is never returned back to the powdery dyestuff diffusible into the fused heat-fusible Sub original one even if the heat-fusible Substance is cooled, stance through dispersion or dissolution. after the color tone change, and Solidified. Examples of Such Substrates are paper Such as plain paper, When practically using these heat-Sensitive indicators, Japan art paper and Kent paper, Synthetic paper, wood Such they are arranged near the product of which temperature as Sun tree timber; and plastic Substrates Such as history is to be detected or they are adhered to Such a polypropylene, polyethylene terephthalate, acrylonitrile product. Alternatively, it is also possible to directly print butadiene-styrene resin, polycarbonate and acrylic resin Such a product with the heat-Sensitive ink. Substrates. These heat-sensitive indicators may be in the form of a 1O EXAMPLES card-like, sheet-like or rod-like shape. Alternatively, they The irreversible heat-Sensitive composition, the heat may be labels, which carry an adhesive layer on the back Sensitive ink containing the composition and the heat face. Sensitive indicator using the ink thereof according to the The printing of the substrate with the heat-sensitive ink is present invention will hereunder be described in more detail performed by, for instance, Screen-printing, offset printing, 15 with reference to the following Examples. gravure printing and brush coating techniques. In the following Examples 1 to 121, there are embodied The ink layers formed on the substrate by printing with the preparation of the irreversible heat-Sensitive composi these heat-Sensitive inkS may be covered up with a trans tions according to the present invention, while in the fol parent or translucent laminate material made of a resin. lowing Comparative Examples 1 to 6, there are embodied Examples of Such laminate materials are plastic films Such compositions, which are beyond the Scope of the present as polypropylene, polyethylene terephthalate, acrylonitrile invention. butadiene-styrene resin, polycarbonate and acrylic resin films, and printing mediums for laminate Such as acrylic Examples 1 to 121 resins, nylon and phenol resin. 25 A heat-fusible Substance was blended with 0.001 to 100 In these heat-Sensitive indicators, the heat-fusible Sub parts by weight of a dyestuff, which underwent a color tone stance and the dyestuff are in a mixed State, prior to heating. change when it is dissolved or dispersed in or wetted with If the indicator is heated to a temperature higher than the the heat-fusible substance after the fusion thereof, per 100 melting point of the heat-fusible Substance, however, the parts by weight of the former and then the resulting blend dyestuff diffuses into the fused heat-fusible substance was pulverized, using a mortar and a pestle, to Such an extent through dispersion or dissolution or the Surface of the that the particle size of the heat-fusible substance fell within granular or powdery dyestuff is wetted with the fused the range of 0.01 um to 5 mm and that the particle size of heat-fusible Substance So that the indicator undergoes a the dyestuff fell within the range of 0.001 um to 5 mm to thus desired color tone change. Alternatively, in case of the give each corresponding composition. Each prepared com indicator, which makes use of microcapsules, the heat 35 position was heated till it was fused and then the fused fusible substance and the dyestuff enclosed in the micro composition was cooled till re-Solidified to thus confirm any capsules may be permeated through the outer wall of the color tone change of the composition. The kinds and microcapsules and diffuse into the ink vehicle, after the amounts of part by weight, color tone before and after the fusion of the heat-fusible Substance by heating. color change and the melting temperature of the heat-fusible This diffusion of the foregoing components is irreversible. 40 Substances and dyestuffs are Summarized in the following Therefore, once the indicator undergoes a desired color tone Tables 1 to 4.

TABLE 1. Examples 1 to 30 After Indicating Heat-fusible Before re-solid- Point Ex. Substance Amount Dyestuff Amount heating ification ( C.) 1 Myristic acid OO Acid Yellow 0.1 White Yellow 50 73 2 Palmitic acid OO Basic Yellow 0.1 White Yellow 60 11 3 Adipic acid OO Basic Red 38 1. White Red 150 4 Octanoic acid 00 Pigment 1OO White Yellow 17 Yellow23-Lake 5 Tricosanoic 00 Pigment Blue 50 White Blue 79 acid 15 6 Tetratriaconta- 00 Pigment 50 White Yellow 98 noic acid Yellow 34 7 2,3-Dimethyl- OO Carbon Black 1O White Black 122 nonanoic acid 8 23-Methyl- OO Direct 0.001 White Orange 83 tetracosanoic Orange 39 acid 9 2-Hexenoic OO Mordant Red 1. White Red 32 acid 7 10 Brassidic acid OO Azoic Blue 9 1. White Blue 62 11 2-Methyl-2- OO Vat Green 9 0.1 White Green 33 US 6,602,594 B2 9 10

TABLE 1-continued Examples 1 to 30 After Indicating Heat-fusible Before re-solid- Point Ex. Substance Amount Dyestuff Amount heating ification ( C.) dodecenoic acid 12 B-Eleostearic OO Mordant 1. White Black 72 acid Black 38 13 Behenolic acid OO Sulfur Black 1 0.01 White Black 58 14 cis-9,10 OO Solvent Blue 1. White Blue 87 Methylene 25 octadecanoic acid 15 Chaulmoogric OO Cathillon Red 0.01 White Red 69 acid SGLH 16 n-Dodecyl 3,3'- OO Direct Brown 1. White Brown 40 thiodipropionate 2 17 Trilaurin OO Sulfur Red 5 0.1 White Red 45 18 Palmitic acid 00 Reactive Blue 1. White Blue 85 anilide 19 19 Stearic acid OO Basic Red 38 1. White Red 90 amide Zinc stearate OO Acid Yellow 0.1 White Yellow 110 73 21 Salicylic acid 00 Disperse Blue 1. White Blue 130 anilide 3 22 N-Acetyl-L- OO Wat Violet 2 0.1 White Purple 190 glutamic acid 23 Caproic acid 00 Reactive Blue 1. White Blue 107 B-naphthyl 15 amide 24 Enanthic acid OO Solvent 0.001 White Orange 103 phenylhydrazide Orange 2 25 p-Chlorophenacyl 00 Azoic Diazo 0.1 White Red 86 arachionate Component 11 26 Cholesteryl 00 Remazol 0.1 White Blue 96 formate Brilliant Blue R-KN 27 1-Aceto-2,3- OO 4,10-Dibromo- 1. White Red 57 distearin anthanthrone 28 Pentadecyl 00 Dibenzo- 1O White Black 52 thiolaurate anthrone 29 Stearic acid OO Cochineal 1O White Red 23 chloride lake Palmitic acid 00 Pigment 1OO White Yellow 64 anhydride Yellow 1

TABLE 2 Examples 31 to 60 After Indicating Heat-fusible Before re-solid- Point Ex. Substance Amount Dyestuff Amount heating ification ( C.) 31 Stearic acid OO Mordant Red 1. White Red 54 acetic acid 7 anhyride 32 Succinic acid OO Direct Orange 0.1 White Orange 185 39 33 Sebacic OO Acid Red 52 0.01 White Red 122 acid benzyl ammonium salt 34 2-Bromovaleric 00 Pigment Red 50 White Red 67 acid 209 35 Methyl C OO Basic Yellow 0.1 White Yellow 18O sulfostearic 11 acid sodium salt 36 2-Fluoroarachic OO Azoic Blue 9 1. White Blue 90 acid 37 Octadecyl OO Primuline 1. White Yellow 55 alcohol Sulfonic Acid US 6,602,594 B2 11 12

TABLE 2-continued Examples 31 to 60 After Indicating Heat-fusible Before re-solid Point Ex. Substance Amount Dyestuff Amount heating ification ( C.) 38 Cholesterin OO Pigment Red 50 White Red 140 38 39 D-mannitol OO Basic Red 50 hite Red 165 1-Lake Galactitol OO Reactive Blue 1. hite Blue 185 15 Hepta OO Disperse Blue 3 1. hite Blue 91 triacontanol Hexadecan OO Basic Yellow O.1 hite Yellow 44 2-ol 11 1-trans-2- OO Pigment hite Yellow 48 Octadecenol Yellow 109 B-Eleostearyl OO Cathillon Red hite Red 59 alcohol SGLH Cycloeicosanol OO Azoic Diazo O.1 hite Red 69 Component 11 d(+)Cellobiose OO Pigment Blue 50 hite Blue 18O 15 pp'-Biphenol OO Basic Yellow O.1 hite Yellow 28O 11 Riboflavin OO Solvent Blue hite Blue 32O 25 4-Chloro-2- OO Acid Red 1O hite Red 47 methylphenol 87-Lake 50 2-Bromo-1- OO Acid Red 52 hite Red 131 indanol 51 Dihexadecyl OO Pigment Blue 6 50 hite Blue 54 ether 52 Dioctadecyl OO Dibenzo hite Black 59 ether anthrone 53 Cytidine OO Solvent hite Orange 210 Orange 2 54 Adenosine OO Sulfur Black 1 hite Black 22O 55 Sodium OO Pigment hite Green 240 phenoxy Green 10 Acetate 56 1,3-Bis(4-hydroxy OO Acid Yellow 73 O.1 W hite Yellow 130 phenoxy)- benzene 57 Aluminium OO Pigment Red 50 hite Red 159 triethoxide 88 58 Stearin OO Sulfur Red 5 O.1 hite Red 38 aldehyde 59 Paralauryl OO Pigment Red 50 hite Red 57 aldehyde 179 60 Parastearin OO Mordant Red hite Red 78 aldehyde 7

TABLE 3 Examples 61 to 90 After Indicating Heat-fusible Before re-solid Point Ex. Substance Amount Dyestuff Amount heating ification ( C.) 61 Naphtho Sulfur Black 1 White Black 61 aldehyde 62 p-Chlorobenz Wat Violet 2 White Purple 48 aldehyde 63 Phthalaldehyde Acid Green 1 O1 White Green 99 64 4-Nitrobenz 4,10-Dibromo 1. White Red 105 aldehyde anthanthrone 65 Stearone Sulfur Black 1 White Black 89 66 DocOSan Basic Red 38 White Red 64 2-one 67 Phenyl Pigment 50 White Green 59 heptadecyl Green 8 ketone 68 Cyclonona Azoic Blue 9 White Blue 72 US 6,602,594 B2 13 14

TABLE 3-continued Examples 61 to 90 After Indicating Heat-fusible Before re-solid Point Ex. Substance Amount Dyestuff Amount heating ification ( C.) decane 69 Vinyl OO Reactive Blue 1. White Blue 41 heptadecyl 15 ketone 70 4,4-Bisdimethyl OO Pigment Red 50 White Red 170 aminobenzo 209 phenone 71 Bis(2,4-pentane OO Cochineal 1O White Red 290 dionite) lake calcium 72 1-Chloro OO Sulfur Black 1 0.01 White Black 210 anthraquinone 73 Tricosylamine OO Acid Yellow 0.001 White Yellow 63 73 74 Dioctadecyl OO Pigment Red 50 White Red 72 amine 88 75 N,N-Dimethyl OO Direct 0.1 White Orange 191 octylamine Orange 39 76 Heptadeca OO Pigment 50 White Yellow 65 methyleneimine Yellow 23-Lake 77 Naphthyl OO Pigment 1O White Purple 113 Amine Violet 23 78 Ethyl p-amino OO Tannic 1. White Black 90 Benzoate acid-Gallic acid-Iron lake 79 o-Trithiourea OO Pigment Blue 50 White Blue 160 15 Sulfamethazine OO Pigment Red 50 White Red 195 53 81 Guanidine OO Solvent 0.01 White Orange 2OO nitrate Orange 2 82 p-Chloroaniline OO Flavianic 1OO White Yellow 71 Acid Disodium Salt 83 Propylamine OO Acid Yellow 0.01 White Yellow 161 hydrochloride 73 84 Hexylamide OO Acid Red 52 0.01 White Red 101 85 Octacosyl OO Acid Yellow 0.01 White Yellow 119 Amide 73 86 N-Methyl OO Acid Violet 49 0.1 White Purple 56 dodecylamide 87 N-Methyl OO Basic Yellow 0.1 White Yellow 98 heptacosyl 11 Amide 88 C-Cyanoacet OO Discharge 0.01 White Red 12O amide Red BB 89 Salicylamide OO Carbon Black 1O White Black 140 90 Dicyandiamide OO Pigment 50 White Yellow 2OO Yellow 23-Lake

TABLE 4 Examples 91 to 121 After Indicating Heat-fusible Before re-solid Point Ex. Substance Amount Dyestuff Amount heating ification ( C.) 91 2-Nitrobenz Pigment Blue 50 White Blue 175 amide 15 92 N-Bromo Pigment 50 White Yellow 105 acetamide Yellow 34 93 Pentadecane Azoic Diazo O.1 White Red 23 nitrile Compon-ent 11 94 Margaronitrile Sulfur Black 1 White Black 34 95 2-Naphtho Pigment White Purple 63 nitrile Violet 23 US 6,602,594 B2 15 16

TABLE 4-continued Examples 91 to 121 After Indicating Heat-fusible Before re-solid- Point Ex. Substance Amount Dyestuff Amount heating ification ( C.) 96 o-Nitrophenoxy- 00 Reactive Blue 1. White Blue 155 acetic acid 19 97 3-Bromo- OO Aluminum 1O Yellow White 39 benzonitrile hydroxide 98 3-Cyanopyridine 00 Acid Green 1 0.1 White Green 83 99 4-Cyano- OO Vat Green 9 0.1 White Green 112 phenol OO Hexadecane OO Basic Red 38 1. White Red 18 O1 1-Nonatri- 00 Disperse Blue 1. White Blue 78 acontene 3 O2 trans-n-2- OO Vat Green 9 0.1 White Green 13 Octadecene 03 Hexatriacontyl- 00 Pigment Red 50 White Red 8O benzene 38 04 2-Methyl- OO Alizarin Lake 1O White Red 35 naphthalene 05 Picene OO Solvent Blue 1. White Blue 368 25 06 Cyanuric 00 Pigment 50 White Yellow 147 chloride Yellow 35 O7 1-Fluoro- OO 4,10-Dibromo- 1. White Red 39 nonadecane anthanthrone 08 1-Chloro- 00 Remazol 0.1 White Blue 38 eicosane Brilliant Blue R-KN 09 1-lodo- OO Strontium 1O Yellow White 24 pentadecane sulfate O 1-Bromo- OO Direct 0.1 White Orange 3O heptadecane Orange 39 1 1,2,4,5-Tetrakis- OO Solvent 0.01 White Orange 160 (bromomethyl)- Orange 2 benzene 2 Pentadecane OO Primuline 1. White Yellow 18 thio Sulfonic Acid 3 Eicosane thiol OO Kaolin 1O Yellow White 37 4 2-Naphthalene 00 Disperse Blue 1. White Blue 8O thio 3 5 2-Mercapto- OO Vat Green 9 0.1 White Green 8O ethyl ether 6 2-Nitrobenzene OO Prussian Blue 1. White Blue 75 sulfenyl chloride 7 1,3-Diatine 00 Pigment 1OO White Yellow 53 Yellow 1 8 2,11-Dithia- OO Titanium 50 Yellow White 222 3,3 para- dioxide cyclophane 9 Bis-(4-hydroxy-3- 00 Disperse Blue 1. White Blue 123 methylphenyl) 3 sulfide 20 4,4-Dipyridyl OO Calcium 1O Yellow White 65 sulfide silicate 21 4-Methyl- 00 Remazol 0.1 White Blue 84 mercapto- Brilliant Blue phenol R-KN

The results of the foregoing Examples clearly indicate 55 low temperature to a high temperature, or the color tone that the granular or powdery dyestuff is covered with the change-temperature can be well Systematized. granular or powdery heat-fusible Substance in the irrevers ible heat-Sensitive composition of the present invention and Comparative Examples 1 to 6 that the composition undergoes a color tone change when heated and the color tone is never returned back to the In these Comparative Examples 1 to 6, irreversible heat original one even if the composition is again solidified with " Sensitive compositions were prepared by repeating the same cooling. The results shown in Tables 1 to 4 also indicate that procedures used in Example 1 except for the following a wide variety of irreversible heat-Sensitive compositions points. The heat-fusible Substance of each composition thus whose indicating point ranges from 13 to 368 C. can be prepared was heated till it was fused and thereafter the fused prepared by variously combining heat-fusible Substances composition was cooled till it was re-Solidified to thus and dyestuffs. This clearly indicates that the temperature at 65 confirm the color tone of the composition. The kinds and which the composition undergoes a color tone change may amounts (part by weight), color tone before and after the arbitrarily be Selected over a wide range extending from a color change and the indicating temperature of the heat US 6,602,594 B2 17 18 fusible Substances and dyestuffs are Summarized in the around the melting point of the heat-fusible Substance, if following Table 5. either of the foregoing requirements is beyond the Scope Comparative Ex. 1: The amount of the dyestuff was defined above. changed to 0.0001 part by weight. Then heat-Sensitive indicators were manufactured by way Comparative Ex. 2: The amount of the dyestuff was of trial using the heat-Sensitive ink according to the present changed to 200 parts by weight. invention in the following Examples 122 to 127, and heat Sensitive indicators were likewise manufactured by way of Comparative Ex. 3: The heat-fusible substance was pull trial using heat-Sensitive inks, which were beyond the Scope Verized by a mortar and a pestle to Such an extent that of the present invention, in Comparative Examples 7 to 9. the particle size thereof was less than 0.01 um. Comparative Ex. 4: The heat-fusible substance was pull Verized by a mortar and a pestle to Such an extent that Example 122 the particle Size thereof was greater than 5 mm. A heat-fusible Substance, a dyestuff, an ink vehicle and a Comparative Ex. 5: The dyestuff was pulverized by a Solvent were admixed together in the amounts Specified in mortar and a pestle to Such an extent that the particle 15 the following Table 6, followed by uniformly kneading the size thereof was less than 0.001 um. resulting mixture to give a heat-Sensitive ink. The resulting Comparative Ex. 6: The dyestuff was pulverized by a ink was printed on the Surface of Synthetic paper of a plastic, mortar and a pestle to Such an extent that the particle which is a Substrate, by the Screen-printing technique to give Size thereof was greater than 5 mm. a heat-Sensitive indicator.

TABLE 5 Comparative Examples 1 to 6 After Indicating Comp. Heat-fusible Before re-solid Point Ex. Substance Amount Dyestuff Amount heating ification ( C.) 1. Myristic acid 100 Acid Yellow 0.0001. White White 50

2 Myristic acid 1OO Aid Yellow 200 Yellow Yellow 50 3 Myristic acid 1OO Aid Yellow O1 White White 50 4 Myristic acid 1OO Aid Yellow O1 Yellow Yellow 50

5 Myristic acid 1OO Aid Yellow O1 White White 50 6 Myristic acid 1OO Aid Yellow O1 Yellow Yellow 50 73

The results of the foregoing Comparative Examples 1 to 40 Examples 123 to 127 and Comparative Examples 7 6 clearly indicate that the achievement of an intended object to 9 of the present invention or the preparation of the irreversible heat-Sensitive composition can simply be attained if the The same procedures used in Example 122 were repeated following requirements are Satisfied: the amount of the except that the heat-fusible Substance, dyestuff, ink vehicle dyestuff should fall within the range of from 0.001 to 100 45 and solvent were used in the amounts specified in Table 6 to parts by weight per 100 parts by weight of the heat-fusible give each corresponding heat-Sensitive indicator. Substance; the particle size of the heat-fusible Substance The indicators manufactured in Examples 122 to 127 and should be limited to the range of from 0.01 um to 5 mm; and Comparative Examples 7 to 9 by way of trial were heated in that of the dyestuff should be limited to the range of from 50 a thermostatic chamber to thus determine the temperature at 0.001 um to 5 mm. In other words, a particular heat-sensitive which each indicator underwent a color tone change. The composition never undergoes any color tone change at results thus obtained are listed in Table 6.

TABLE 6

Heat Color tone

fusible Dye- Before After Temp.* Substance stuff Ink vehicle Solvent heating heating ( C.) Examples 122 Myristic Acid Ethyl Diethyl White Yellow 50 acid (100) Yellow cellulose benzene 73 (0.1) (8) (200) 123 Stearic acid Basic Acrylic Isoamyl White Red 90 amide (100) Red 38 resins (7) acetate (1) (200) US 6,602,594 B2 19

TABLE 6-continued

Heat Color tone fusible Dye Before After Temp.* Substance stuff Ink vehicle Solvent heating heating ( C.) 124 B-Eleostearyl Cathillon PAS800 Butyl White Red 59 alcohol (100) Red medium cellosolve SGLH (50) (50) (0.01) 125 Salicylamide Carbon High Set Mat Mineral White Black 140 (100) Black Medium (60) spirit (50) (10) 126 Cyclo- Azoic Ethyl Diethyl White Blue 72 nonadecane Blue 9 (1) cellulose (8) benzene (100) (200) 127 1,2,4,5-Tetrakis Solvent Hydroxy-m Water White Orange 160 (bromomethyl) Orange ethyl (150) benzene 2 (0.01) cellulose (100) (8) Comparative Examples 7 Myristic Acid High Set Mat Mineral Yellow Yellow acid (100) Yellow Medium (60) spirit (50) 73 (0.1) 8 Stearic acid Basic Hydroxy-m Water Red Red amide (100) Red 38 ethyl (150) (1) cellulose (8) 9 Myristic Acid High Set Mat Mineral White White acid (10) Yellow Medium (60) spirit (50) 73 (0.1) Parts by weight shown in brackets ( ) *: Color changing temperature

AS will be seen from the data shown in Table 6, the mixture was dispersed in a dispersion medium obtained by indicators of Examples 122 to 127 cause distinct color admixing 500 parts by weight of a 2% aqueous solution of changes at predetermined temperatures and can indicate that Sodium alginate and 3 parts by weight of Uramine P-1500 they experience desired temperature histories. Moreover, if 35 (the trade name of a product available from Mitsui Toatsu the indicators were preserved after the color tone changes, Chemicals, Inc.) as a urea resin, followed by stirring the the color tones observed after the color changes were mixture over 20 minutes to give an emulsion. certainly maintained. On the other hand, the indicators of Thereafter, 30 parts by weight of Epicure (the trade name Comparative Examples 7 and 8 were already pigmented at of a product available from Yuka Shell Epoxy K.K.) as a 40 curing agent was added to the resulting emulsion, followed the time of the manufacture of the same by way of trial Since by stirring the mixture for 8 hours to thus form the walls of the heat-fusible substance and the dyestuff had been dis the microcapsules. Solved in the Solvent when kneaded and therefore, the color The resulting liquid was filtered to give microcapsules tone of the indicators observed when they were manufac each of which enclosed the heat-fusible Substance and the tured by way of trial was maintained even after the fusion of dyestuff therein. the heat-fusible Substance. Further, the indicator of Com 45 Then there were kneaded, in a kneader, 100 parts by parative Example 9 never underwent any color change and weight of the resulting microcapsules, 50 parts by weight of thus the original color tone thereof was maintained even PAS800 Medium as an ink vehicle and 50 parts by weight after the fusion of the heat-fusible Substance, because the of butyl cellosolve as a solvent for the ink vehicle to give a amount of the heat-fusible Substance incorporated into the heat-Sensitive ink. The Surface of Synthetic paper of a indicator was too small. 50 plastic, which is a Substrate, was printed with this ink by the Moreover, in the following Examples 128 to 133, heat Screen-printing technique to give a heat-Sensitive indicator. Sensitive indicators were prepared using heat-Sensitive inkS Examples 129 to 133 and Comparative Example 10 according to other embodiments of the present invention, Micro capsules were prepared using polymeric while in the following Comparative Examples 10 to 11, 55 compounds, heat-fusible Substances and dyestuffs in indicators were prepared using inks, which were beyond the amounts Specified in the following Table 7 according to Scope of the present invention. various preparation methods. In this respect, the following methods were substituted for the interfacial polymerization Example 128 method used in Example 128: the phase Separation method Microcapsules used in these Examples were prepared 60 in Examples 129 and 131 to 133; the drying-in liquid method according to the interfacial polymerization technique. in Example 130; and the interfacial polymerization method First, there were mixed 7 parts by weight of a mixture in Comparative Example 10 as in Example 128. Thereafter, containing 99.9% of myristic acid as a heat-fusible Sub the same procedures used in Example 128 were repeated to stance and 0.1% of Acid Yellow 73 as a dyestuff with 30 prepare inkS and to manufacture indicators. parts by weight of Epicoat 828 (the trade name of a product 65 Comparative Example 11 available from Yuka Shell Epoxy K.K.) as an epoxy resin for There were kneaded, in a kneader, 100 parts by weight of forming the outer walls of the microcapsules. The resulting myristic acid, 0.1 part by weight of Acid Yellow 73,50 parts US 6,602,594 B2 21 22 by weight of PAS800 Medium, and 50 parts by weight of tion can be used in printing operations irrespective of the butyl cellulose to give an ink without enclosing the mixture shape thereof. For instance, a printing ink can be prepared in microcapsules. An indicator was prepared by printing a using an appropriate vehicle prior to practical use thereof in Substrate with the resulting ink according to the same printing. In addition, the composition of the present inven manner used in Example 128. tion permits the use of a wide variety of dyestuffs unlike

Blending of heat-sensitive ink Microcapsule Heat-sensitive Polymeric Solvent for ink indicator compounds Ink vehicle vehicle Color tone forming Comprised heat-fusible Mixing Mixing Mixing Before After Temp.* outer wall substance amount amount amount heating heating ( C.) Examples 28 Epoxy Myristic acid:Acid Yellow 73 1OO PAS800 50 Butyl SO White Yellow 50 resins (99.9%:0.1%) medium cellosolve 29 Polystyrene Stearic acid amide: 100 High Set 60 Mineral SO White Red 90 Basic Red38 Mat spirit (99%:1%) Medium 3O Silicone B-Eleostearyl alcohol: 100 Aqua 100 Water 20 White Red 59 resins Cathillon Red SGLH Set Ink (99.99%:0.01%) 31 Polystyrene Salicylamide Carbon Black 1OO VAR-OOO 70 Ethanol 3O White Black 140 (89.9%:10.1%) Medium 32 Polyvinyl Cyclononadecane: 100 Ramistar 100 Isopropyl SO White Blue 72 acetate Azoic Blue 9 R alcohol (99%:1%) Medium 33 Gelatin 1,2,4,5-Tetrakis (bromomethyl) 100 Ethyl 8 Diethyl 2OO White Orange 160 benzene: cellulose benzene Solvent Orange 2 (99.99%:0.01%) Comparative Examples 1O Epoxy Myristic acid:Acid Yellow 73 1O PAS800 50 Butyl 3O White White resins (99.9%:0.1%) medium cellosolve 11 None Myristic acid:Acid Yellow 73 100.1 PAS800 50 Butyl 50 Yellow Yellow (100:0.1 parts by weight) medium cellosolve *: Color changing temperature

The indicators prepared in Examples 128 to 133 and those, which make use of chemical decomposition or chemi Comparative Examples 10 to 11 were heated in a thermo cal reactions of dyestuffs. This composition also permits the Static chamber to thus determine the temperature at which establishment of a variety of color change temperatures each indicator underwent a color tone change. The results 45 extending from a low temperature to a high temperature, by thus obtained are Summarized in Table 7. variously combining different heat-fusible Substances and AS will be seen from the data listed in Table 7, the dyestuffs. This accordingly permits the Systematization of heat-sensitive indicators of Examples 128 to 133 undergo the color change temperatures of Such irreversible heat distinct color changes at desired temperatures and could Sensitive compositions. indicate that they experienced the desired temperature his 50 Heat-Sensitive indicator can be mass-produced by the tories. Moreover, the heat-Sensitive indicators were pre printing operations if using the heat-Sensitive ink according Served after the color tone changes, but maintained the color to the present invention and this accordingly leads to the tones observed after the color changes and there was not Substantial reduction of the cost required for the production observed any color tone change. On the other hand, the of Such indicators. indicator of Comparative Example 10 maintained its original color tone even after the heat-fusible Substance was fused 55 The heat-Sensitive indicator prepared by printing opera with heating Since the amount of the microcapsules incor tions using this heat-Sensitive ink undergoes an irreversible porated is too small. Further, in case of the indicator of color tone change and can be preserved while maintaining Comparative Example 11, the heat-fusible Substance and the the color tone observed after the color change. dyestuff were dissolved in the solvent when they were Moreover, if microcapsules are used in the heat-Sensitive kneaded together with the latter and the resulting ink was 60 ink, the heat-fusible Substance and the dyestuff encapsulated pigmented at this stage. For this reason, the indicator main in the microcapsules Show excellent Stability and resistance tained the color tone observed after the pigmentation even to environment in the ink. In addition, when preparing an when heating the same. ink, vehicles or solvents for the vehicles to be incorporated Regarding all of the dyestuffs listed in Table 7, “C.I.' of into the ink must not be limited to those in which the each dyestuff is omitted. 65 heat-fusible substance and dyestuff are insoluble and the AS has been discussed above in detail, the irreversible resulting ink is excellent in the printing characteristics and heat-Sensitive composition according to the present inven the preservation Stability after printing. US 6,602,594 B2 23 24 The heat-sensitive indicator of the invention can favor cellulose, hydroxymethyl cellulose, polyvinyl alcohol and ably be used for the confirmation of whether a product such carboxymethyl cellulose. as a processed food product requiring desired temperature 7. The heat-sensitive ink as set forth in claim 5, wherein control is certainly heated to a temperature of not less than it comprises the heat-fusible Substance in an amount ranging a predetermined level in the heating Step of the product; and from 10 to 70% by weight. of whether a product, which must not be heated to a 8. A heat-Sensitive ink comprising microcapsules, which predetermined temperature level, Such as a medical product encapsulate an irreversible heat-Sensitive composition com prising a mixture of a granular or powdery heat-fusible including a drug, a food product or an electric part is not Substance having a melting point corresponding to a tem heated to Such a temperature level or not during distribution, perature to be recorded and a granular or powdery dyestuff Storage and/or use thereof. 1O diffusible into the fused heat-fusible substance through What is claimed is: dispersion or dissolution, and an ink vehicle capable of 1. An irreversible heat-Sensitive composition comprising diffusing the fused heat-fusible substance therein. a mixture of a granular or powdery heat-fusible Substance 9. The heat-sensitive ink as set forth in claim 8, wherein having a melting point corresponding to a temperature to be the outer wall of the microcapsule is formed from a poly recorded and a granular or powdery dyes tuff diffusible into 15 meric compound Selected from the group consisting of the fused heat-fusible Substance, Said heat-fusible Substance polyvinyl alcohol, polystyrene, Silicone resins, epoxy resins, being at least one member Selected from the group consist acrylic resins, urea resins, gelatin, methyl cellulose, ing of fatty acid derivatives, alcohol derivatives, ether polyurethane, waxes, gum arabic, dextrin and nylon. derivatives, aldehyde derivatives, ketone derivatives, amine 10. The heat-sensitive ink as set forth in claim 8, wherein derivatives, amide derivatives, nitrile derivatives, hydrocar it comprises the microcapsule in an amount ranging from 10 bon derivatives, thiol derivatives and Sulfide derivatives, to 70% by weight. through dispersion or dissolution. 11. A heat-Sensitive indicator comprising a Substrate pro 2. The irreversible heat-sensitive composition as set forth Vided thereon with a printed heat-Sensitive ink layer, in claim 1, wherein the amount of the dyestuff ranges from wherein the heat-Sensitive ink comprises an irreversible 0.001 to 100 parts by weight per 100 parts by weight of the 25 heat-Sensitive composition, which comprises a mixture of a heat-fusible Substance. granular or powdery heat-fusible Substance having a melting 3. The irreversible heat-sensitive composition as set forth point corresponding to a temperature to be recorded and a in claim 1, wherein the heat-fusible Substance has a particle granular or powdery dyestuff diffusible into the fused heat Size ranging from 0.01 um to 5 mm. fusible Substance, Said heat-fusible Substance being at least 4. The irreversible heat-sensitive composition as set forth one member Selected from the group consisting of fatty acid in claim 1, wherein the dyestuff has a particle size ranging derivatives, alcohol derivatives, ether derivatives, aldehyde from 0.001 um to 5 mm. derivatives, ketone derivatives, amine derivatives, amide 5. A heat-sensitive ink comprising an irreversible heat derivatives, nitrile derivatives, hydrocarbon derivatives, Sensitive composition, which comprises a mixture of a thiol derivatives and Sulfide derivatives, through dispersion granular or powdery heat-fusible Substance having a melting 35 or dissolution, and an ink vehicle capable of diffusing the point corresponding to a temperature to be recorded and a fused heat-fusible Substance therein. granular or powdery dyestuff diffusible into the fused heat 12. A heat-Sensitive indicator comprising a Substrate fusible Substance, Said heat-fusible Substance being at least provided thereon with a printed heat-Sensitive ink layer, one member Selected from the group consisting of fatty acid wherein the heat-Sensitive ink comprises microcapsules, derivatives, alcohol derivatives, ether derivatives, aldehyde 40 derivatives, ketone derivatives, amine derivatives, amide which encapsulate an irreversible heat-Sensitive composi derivatives, nitrile derivatives, hydrocarbon derivatives, tion comprising a mixture of a granular or powdery heat thiol derivatives and Sulfide derivatives, through dispersion fusible Substance having a melting point corresponding to a or dissolution; and an ink vehicle capable of diffusing the temperature to be recorded and a granular or powdery fused heat-fusible Substance therein. 45 dyestuff diffusible into the fused heat-fusible substance 6. The heat-sensitive ink as set forth in claim 5, wherein through dispersion or dissolution, and an ink vehicle capable the ink vehicle is a member Selected from the group con of diffusing the fused heat-fusible substance thereto. Sisting of acrylic resins, phenol resins, nylons, ethyl k k k k k