Printing Textile Fabrics with Xerography by W

TA! __ Printing Textile Fa rics with Xerography td/3

BY W. W. CARR. F. L. COOK, W. R. LANIGAN, M. E. SIKORSKI and W. C. TINCHER, Georgia Institute of Technology. Atlanta

ver the past few years, the textile Background rapidly. Thus the time available for devel- 0 industry has moved toward quick oping the charged pattern is extremely response, just-in-time delivery and shorter Applications of Chemicals to short. Since much of the fabric to be process runs to facilitate frequent style Textiles Without the Use of Liquids printed contains cotton, the charge dissi- and color changes. Reduced process effi- The textile xerographic investigation was pation problem would have to be solved. ciency accompanies short runs unless part of a larger project (I), funded by the The other problem is related to the nature changeover downtime is small. Processes U.S. Department of Energy (DOE), in of the fabric surface. Developing the such as continuous carpet dyeing have which several techniques for applying charge image without the entrapment of been modified to minimize time required chemicals to textiles without the use of toner in uncharged regions of the fabric for changeover. However, current fabric liquids were investigated. The objective of would probably be difficult. Sincexerogra- printing systems do not lend themselves to the project was to develop techniques for phy is a highly developed technology for rapid changeover. reducing the energy consumed by the paper printing without these problems, it Rotary screen printing, currently the textileindustry in wet processing. Muchof was the method of choice. predominant method of fabric printing, the energy utilized in wet processes goes has several disadvantages. Color and pat- toward heating and evaporating water. Xerography tern changes require long process set up Energy conservation research has led to a time. Screen production is slow and expen- reduction in thequantity of water required Advantages/Disadvantages 11 sive. Screens have relatively short lives and in wet processing; however, liquids are still Xerography has several potential advan- require considerable storage space when used. Further reductions in energy con- tages for printing fabrics. One is informa- not being used. Thus a new technology for sumption are possible by the complete tion storage can be either optical or com- fabric printing is needed that will permit elimination of liquids. puterized, eliminating the need for large frequent style and color changes with storage space for screens. Since the system minimum downtime for changeover and New Technologies can be computerized, fast style and color will allow computer storage of design Fabric printing was one area selected for changeover are possible. Another is the information. Xerographic printing has the study in the DOE project. Technologies potential for producing color using three potential of meeting these requirements. eliminating water from fabric printing primaries. Theresolution needed for print- whilc having promise of relieving response ing apparel fabrics should be attainable time and information storage problems and image development can be achieved associated with screen printing were con- without the use of solvents. Pigments, sidered.Twomajorcandidates wereinkjet which are generally much less expensive printing and electrophotography. Al- ABSTRACT than dyes and offer better lightfastness though ink jet printing has promise, disad- and other properties, can be used for A three-phase investigation of the use of vantages are associated with it. The major coloration. Washing and drying following xerography for color printing of textiles one is that it is liquid based which elimi- printing is eliminated. has been conducted. Phase I studied the nated it as a candidate for the DOE While xerography has much promise feasibility of using xerography to project. Other disadvantages include: high for fabric printing, current technology has produce clear prints on textiles and to resolution needed for apparel is probably been developed for paper printing. Fabric identify textile toner candidates. Phase unattainable; insoluble dyes such as dis- II demonstrated continuous xerographic, printing has requirements beyond those single-color printing of polyester/cotton perse dyes and pigments are not compati- for paper printing. Xerographic paper sheeting fabric. Phase 111 involved scale ble with the technique; dyes used in the printing systems have been designed pri- up to continuous three-foot wide, process must have the proper textile char- marily for operating in the batch mode (a three-color, complex textile printing. acteristics and influence on rheology; and single sheet is normally printed) and for Textile color xerography was shown to the use of three primaries to produce color fairly narrow widths (usually 8%inches). be a feasible route to waterless, complex is probably not attainable. Fabric printing systems will need to print Printing of fabrics with plgment and Electrophotography (2) involves the much wider webs in a continuous mode. binders. formation of a latent image and trans- The toner requirements for paper printing forming it into a visible image or print. are also quite different from those for KEY TERMS Two types of electrophotography were textile applications. The binders in paper considered for fabric printing: direct im- toners normally consist of styrenejacry- Binders aging on the fabric and xerography. Direct late copolymers with poor adhesion to Colorfastness to Crocking imaging eliminates some of the steps of textile fibers and low drycleaning solvent Electrophotography xerography, but presents two problems not fastness. Printing associated with it. Preliminary tests indi- Triboelectric Attraction Basic Steps Xerography cated that cotton-containing fabrics, under standard conditions of 65% relative The basic steps of xerography are illus- humidity and 20C, dissipate charge very trated in Fig. 1. Metal that is electrically

May 1991 cm 33 ‘ Color Xerography PC develops the image. The fourth step is Red Toner No. 22-144 (Haloid Xerox the transferring of the developed image to Inc.) and Black Toner Type 10 (Xerox the substrate being printed. The substrate Corp.). These two toners were used to is brought into contact with the PC. The produce prints on fabric which were sub- grounded is coated with a layer of photo- back of the substrate is strongly charged, jected to textile tests. conductor (PC). The first step involves usually by using a corona, so that the toner The carrier components of the two charging the surface of the PC which will transfers to the surface of the substrate. tonerlcarrier systems were isolated by hold a charge in the dark. The charging is The fifth step is fixing the toner to the solvent removal of paper toners. Attempts usually accomplished by passing a corona substrate. The temperature of the toner is were made to make textile developer over the PC surface. The second step raised, causing the resin binder to flow. systems by mixihg the carrier with several involves producing a latent electrostatic Pressure is often used as well as a heat resins and disperse dyes, listed in Table I. image by exposing the PC to light. Since source. Following fixation, the surface of Sublimable disperse dyes were included in light causes the PC to become conductive, the PC is cleaned and the process is the materials considered for toners since charge is drained from the surface in repeated. they had the potential of being used regions that are exposed. This step is without binder for sublimation printing of usually accomplished by reflecting light Phase I 100% polyester fabrics. from an original or passing light through a Objective Tests were performed on two other transparency onto the PC surface. A laser The objectives of Phase I were to investi- paper toners. One was a Kodak magenta driven by a computer can also be used to gate on a bench scale the technical feasi- toner and the other a blue toner provided produce the image. The third step is bility of using xerography to print woven by Hunt Chemical Co. developing the latent image by placing fabrics and to identify binder materials for Research was conducted to identify toner (pigment plus binder) in regions toners meeting textile requirements. commercially available resins suitable for where electrostatic charge is located. De- use as the binder component of developer velopment involves the use of a developer Apparatus systems for xerographic fabric printing. system composed of carrier and toner. The A Haloid single-page batch copier with Over 60 commercially available resins as carrier beads, which usually consist of selenium photoconductive plate was used well as melt blended combinations were metal shot coated with a polymer film, are for printing on 50/50 polyester/cotton screened. The physical/textile properties normally much larger in size than the sheeting fabric (Westpoint Pepperell) and of the resins were compared with a stan- toner particles. The triboelectric charac- for screening potential textile toners. dard screen printing resin currently used teristics of the toner and carrier are such by the textile industry, Hycar 26120. The that when they are thoroughly mixed, they Materials standard is a complex acrylic polymer become oppositely charged and attract Initial tests were performed using paper- produced by BF Goodrich Co. each other. The carriEr is oppositely toners; however, since paper toners have charged from the PC surface. When car- not been designed to meet textile require- Tests rier which holds toner on its surface is ments, screening of binder materials with Wet and dry crockfastness tests c were brought intocontact with the PC, the toner potential of meeting textile requirements performed using AATCC Test Method is attracted to charged regions of the PC. was begun. Two toner/carrier systems 8-1972. Samples produced by the Haloid Transfer of toner to these regions on the designed for paper xerography were used: batch system and by sprinkling powder on polyester/cotton sheeting and curing at L 150C for one to two minutes were tested. DOCUMENT Screening tests were conducted to iden- . , tify resins having the proper film/textile .R’ properties to act as a toner component in , xerographic printing of woven fabrics. I . r- +++ +++ +++ ‘4 Desirable binder film properties included: clarity, low melt viscosity, good adhesion XERO to substrate, good physical properties, P good heat and chemical resistance, and 1. CHARGE 2. EXPOSE good wearability. Physical properties were either measured or taken from the literature. The following information was com- piled for the candidate resins: melt temperature, melt viscosity, film forming characteristics, adhesive properties and stress/strain properties. Films of the resins and blends were melt formed while a film of Hycar 26120 was r laid down from an emulsion using a 3. DEVELOP 4. TRANSFER Gardner Knife. An Instron was used to obtain stress/strain properties of the films. h The mechanical properties of Hycar 26120 film were used as a standard for judging the behavior of the candidate materials.

Results and Discussion Clear prints were made using the Haloid 5. FIX process and the paper toners (Red Toner No. 22-144 and Black Toner Type 10). Fig. 1. Basicsteps in xerography. Results of crockfastness tests for the sam-

34 CO3 Vol. 23, No. 5 Table 11. Wet/Dry Crockfastness Test Results for Xerographic Print on Polyester/Cotton Sheeting Fabric' Coverage/Affinity Observation I I

Wet Crocking Dry Crock Rating of Paper Toner Rating Paper Toner

Red (Haloid) 3-4 3 Black (Xerox) 2-3 1 -_Magenta (Kodak) 4 1 aTests were performed according to AATCC Test Method 8-1972.

Four of the other blends (samples 8-11) had melt viscosities in the 3000 to 6000 cps Toner TvDe_. 22-144. Haloid Xk;ox Inc. CColoredPaoer Toner Used in Kodak C range and acceptable adhesion results. In Fig. 2, the stress/strain behavior of selected Elvax 410 blends arc compared with those of virgin Elvax 410 and the Table 111. Results of Melt Viscosity and Dot Adhesion Tests with Various Resins and Their Blends standard, Hycar 26120 resin. The film I 1 produced from Hycar 26120 resin had a low initial modulus and an extremely high Sample Blend Melt elongation-to-break. Of the candidate Number .Ratio Material Viscositye Total Adhesion binders, Elvax 4 10 came closest to dupli- 1 Elvax 410a 6.3 X lo6 CPS 89% cating the stress/strain properties of the 2 AC-400b 610 35 standard. Although Elvax 410 had a 3 AC-580' 650 42 4 AC-62gd 200 12 higher initial modulus than the standard, 5 1;l 410a:400b 2600 100 its elongation to break and breaking 6 1:l 41 O:58Oc 1910 88 strength were similar to those for the 7 1:l 410:62gd 2870 9 standard. The film properties of the blends 8 5:4:1 410:400:580 3150 97 did not compare favorably with those of 9 622 410:400:580 3500 88 10 721 410:400:580 5150 84 the Hycar 26 120. For example, the stress/ 11 7:1:2 41 0:400:580 6010 83 strain plot for 8:1:2 and 9:1:2 blends 12 8:1:2 410:400:580 9000 - (samples 12and 13 inTableIII) areshown 13 9:1:2 41 0:400:580 10,000 - in Fig. 2. Even small amounts of AC-400 - 4 'A polyethylene-co-vinyl acetate, Du Pont. bA polyethylene-co-vinyl ace- and AC-580 blended with Elvax 410 tate, Allied. =A polyethylene-co-vinyl acrylic acid, Allied dAn oxidized poly- caused brittleness, resulting in high initial ethylene, Allied. eMeasuredusing a Model LVT Brookfield Viscometer, Spin- moduli and breaking strengths but ex- dle 4, at 200C. tremely low elongations to break. Based on the results, the melt blend approach was pres are summarized in Table XI. Since tions of materials were screened as poten- abandoned and the virgin Elvax 4 10 was printed fabrics are generally expected to tial binders for fabric toners, Elvax 410 (a chosen as the primary candidatefor textile have ratings of four or above to be accept- polyethylene-co-vinyl acetate produced toner development. able, the paper toners failed to meet the by Du Pont) was selected as the primary industrial standard. candidate. Elvax 410 had good film form- The resins of the paper toner were likely ing and adhesive properties while having Phase II polystyrene-co-acrylate materials, com- stress/strain properties (see Fig. 2) rea- Objective mon within the paper xerographic indus- sonably in the range of the standard, Theobjectives of Phase I1 were to continue try. Since paper toners are not designed to Hycar 26120 resin. The major problem the development of a suitable toner for meet textile fastness requirements, the associated with Elvax 410 was that its melt xerographic printing of polyester/cotton results of the crockfastness tests were not viscosity (approximately IO6 cps) was sheeting fabric and to demonstrate the surprising. The results confirmed the need appreciably higher than the target value continuous xerographic printing of fabric. for the development of new toner materials (approximately 1000 cps) believed to be A beam-to-beam printing process with a meeting textile requirements. needed for good flowability. Blends of single color was developed. When the carriers isolated from the tWG Eivax 410 with several other materials developer systems were mixed with candi- were made in an attempt to reduce melt Apparatus date toners, developer systems (carrier/ viscosity of the base Elvax 410 polymer A review of commercial paper xerography toner) were not produced. Visual observa- while maintaining desirable binder film copiers was made to identify a copier that tion (Table I) of the coverage of the toner properties. Materials used in the blending could be most easily modified for continu- on the carrier showed that, for most tests included various Allied Chemical ously printing fabric. Hunt Chemical, a materials, very little triboelectric attrac- copolymers of the ethylene or ethylene paper toner manufacturer, assisted in this tion occurred between the carrier and the acrylic copolymer type, but with lower part of the project and recommended a toner candidates. The results indicated a molecular weight. The results of melt Xerox Model 3100 copier. The layout of need for testing with a wider range of viscosity and dot adhesion tests are shown the copier facilitated conversion from carriers So that toner could be better in Table 111. Two of the blends, samples 5 paper feed to fabric feed which would matched with carrier. and 6, at a 1:l weight ratio gave promising allow continuous printing of 8Y2 inch wide After Over 60 commercially available melt viscosities, while yielding adhesion fabric. One of the Xerox copiers was used materials as Well as melt blended combina- results comparable to virgin Elvax 410. to obtain the operational characteristics of

May1991 35 Color Xerography

400

the model. Another copier was modified to allow manual control of major components of the system and to permit continu- cn- c ous operation for fabric printing. Under Y manual control, it was possible to vary vj cnw copier parameters during testing. The d rJ/ -I t- c-3- -x following modifications were made to the cn 200 Xerox 3 100copier: installation of variable speed motor to allow control of fabric speed; rewiring of exposure light; installation of a variable voltage power supply to f A S 12blend allow varying magnetic brush speed; installation of controls for fusing system; installation of let off and take up rolls for the fabric; and attachment of power SUP- -4 plies to four corotrons and the developer 0. uIllrlllll.ll cage. I3.0 2.0 4.0 1 Materials SI1 :RAIN. Paper developer systems (toner plus carrier) compatible with the Xerox 3100 Fig. 2. I:ilm s1ires ,/strai n curve compariscms of blend and virgin resins. copier were used initially to demonstrate continuous xerographic printing of fabric. While the continuous xerographic fabric Production of developer systems using operations. Subsequent attempts to grind printing system was being constructed and the textile toners required finding carriers the material were unsuccessful. Appar- demonstrated, work continued on textile compatible with the toners. Samples of the ently the material is too amorphous for developer systems to satisfy textile print- four textile toners were evaluated by Hunt facile grinding and tends to fibrillate ing requirements. Textile toners for poly- Chemical in an effort to match each of the instead of fragmenting into small parti- ester/cotton blend fabric and 100% poly- toners with a suitable’carrier. cles. ester fabric were sought. The toner for The physical properties of the four Hunt attempted to produce an EVA polyester/cotton blend fabric consisted of candidate toners were evaluated by Huh based toner by spray dr a binder plus pigment while toner for 100% Chemical. The triboelectric properties of Droduced bv Pierce and polyester fabric was sublimable dye with- the-nonpolar disperse dye samples were attempt was unsuccessful because particle out binder. The latter concept was to use such that very little charge was generated formation did not occur. Instead, the heat to transfer thesublimabledyeinto the when the material was thoroughly mixed material coated the inside of the dryer. A polyester so that binder would not be with various carriers. Thus a developer second attempt was made using EVA needed. system could not be made using the Ciba- emulsion loaded with wax, silica and 1 Based on the results of Phase I, polyeth- Geigy disperse dye with the available pigment. Although spra ylene-co-vinyl acetate resin (EVA) was carriers compatible with the Xerox 3 100 in the formation of srr selected as the primary binder candidate copier. triboelectric properties of th;ls EVA toner for the toner for polyester/cotton blend Hunt’s studies revealed that the particle were such that very little charge was 1 fabrics. In addition to Elvax 410, MU 760 size of the EVA toner pigmented by melt generated when the toner was mixed with (another polyethylene-co-vinyl acetate blending was too large and contained fiber various carriers. Generation of a developer which is similar to Elvax 410 but produced like material even though the material had system was thus not possible from spray by U.S. Industries) was also investigated. been processed through several grinding drying the EVA emulsion. I Neither of the two resins were produced As mentioned in the discussion of Phase commercially with pigment, and pig- I, BF Goodrich’s Hycar 26 120 was used as mented samples could not be obtained. LET-OFF the standard textile printing material. Attempts were made to produce toner by Toner could not be produced from it by melt blending of the resins with 5% by w grinding due to the nature of the material. XEROX2510 weight of phthalocyanine blue pigment Thus it was not given serious consideration, and grinding. The blends were processed El as a xerographic toner in Phase I. During through a Wiley mill, a cryogenic grinder, XEROX 2510 Phase 11, Hunt Chemical proposed that aj an air mill and then sieved. toner be produced via sp Candidate toners for polyester fabric 26120, which is an em t were produced two ways. One was pro- 0 complex acrylic polymer, was loaded withi XEROX 2510 duced by grinding and sieving blue dis- 113 silica and pigment and : persedyecake (Cibacet Blue E-GBN, C.I. ples of toner were produ Disperse Blue 3) obtained from Ciba- complex acrylic toner proved to be. Geigy. The other was made by grinding TAKE-UP thermoset material and started to deter1 11L and sieving the same blue disperse dye rate before it melted. Thus it was also no1 diluted with lignin sulfonate filler/dis- Fig. 3. Continuous 36-inch wide xerographic suitable toner for textile xerography. persing agent. printing line. One candidate toner was found 1

36 CCO Vol. 23, NO. Kativo prints was not as good as would characterizing toner were either built or have been desired, they were as good as purchased. those for standard red and black screen 0 Electrical measurement apparatus prints from a textile supplier (Table IV). for the evaluation of carrier materials Triboelectric apparatus to evaluate the charge generating characteristics of Phase 111 toner/carrier combinations Objectives 0 An impedance bridge and sample cell Phase 111 involved scaling up to continu- for dielectric measurements of toner and ous 36-inch wide, three-color textile print- carrier candidate materials ing. One of the objectives was to demon- Since building a 36-inch wide copier strate a xerographic process for printing in-house would have been very difficult 36-inch wide polyester/cotton sheeting and prohibitively costly, a survey was fabric. The prints were to contain three made to locate an existing 36-inch wide colors with regions having single colors copier that could be modified for continu- and two and three overlapping colors. The ous runs. Several 36-inch wide copiers second objective was to continue develop- were identified on the international mar- ment of a toner meeting textile require- ket, but most wereexpensive, costing from ments. $50,000 tomorethan $100,000.0neofthe copiers, the Xerox Model 25 10, was priced Apparatus in the $3000 to $4000 range. An evalua- During the previous two phases of the tion of the Xerox 2510 copier indicated project, Hunt Chemical determined the that it could be modified and used for toner and carrier combinations for the continuous printing of fabric. The copier is was available in a range of colors. Red anc project. For Phase 111, the decision was an optically based, batch type machine blue Kativos were used to produce textile made to develop in-house capabilities for that can make reproductions having d .Kativo contained twc making electrical measurements of toner widths up to 36 inches. It is basically a blue phthol Acrylamide (C.1 and carrier materials to arrive at optimum print reproduction machine that is best 170) and Pyrazol Orange textile developer combinations. The fol- suited for printing lines. Solid areas are Orange 34, #21115). The lowing three measurement systems for difficult to print with the Xerox 2510 blue Kativo contained a phthalocyanine blue pigment, Iron Blue #27 (C.I. Pig .individualimage ment Blue 27, #77510). The triboelectric loops properties-of the Kativos were such that sufficient charge was generated when they were mixed with carrier supplied by Hunt

COPIER 1 COPIER 2 COPIER 3 Fig. 4. lnitial imagingconfiguration.

CONTINUOUS IMAGE LOOP

were then run on the prints using AATCC TestMethod8-1981.

Res sion Crockfastness test results are summarized in Table IV. The drjcrockfastness of the blue Kavito prints was excellent with all samplesexhibiting ratingsof 5, but the wet crockfastness was not as good, ranging from 3 to 5 depending on the size of the printed area-the smaller the area, the higher the rating. The crockfastness rat- h ings of the red Kativo toner were lower than those for the blue Kativo. The crockfastness ratings for dry specimen were 4 COPIER 1 COPIER 2 COPIER 3 while ratings for-wetsamples range from 3 to 4. Although the Wet crockfastness of the Fig. 5. Final imagingconfiguration.

May1991 37 Color Xerography testing. Since the paper toners had been continuous xerographic printing tests developed for operation in the systems were rolls of paper and 50/50 polyester/ closely matching the Xerox 2510 copier, cotton sheeting fabric. The paper was used they werevery useful in demonstrating the to set up the three Xerox 2510 copiers in copier, and some difficulty in printing feasibility of continuously printing fabric series to run continuously to assure the dark, solid areas with the unit was antici- using xerography. However, the required machines were functioning properly. Once pated. However, the Xerox 2510 was textile properties were not generated using the line was operational, the fabric was suitable for demonstrating the continuous these materials. printed using paper toners and then textile xerographic printing of 36-inch wide fab- The materials considered as candidates toners were incorporated. ric. for textile toners in this phase of the Since the Xerox 2510 is a batch type project included Kativo, the modified ep- Tests machine for making one-color prints, sev- oxy produced by H. B. Fuller, and two A number of tests were run to characterize eral modifications were necessary to allow types of polyethylene-co-vinyl acetate pro- toner and carrier. The most useful tests continuous operation. Three of the ma- duced by US.Industries. Since pigmented were those characterizing the triboelectric chines were used in tandem to produce Kativo was commercially available, it properties because the results indicated three-color prints. The Xerox Corp. co- qualified as a toner if it could be matched the compatibility of toner and carrier for operated in this phase of the project, with a carrier. Kativo with several dif- attaining good quality xerographic prints. providing assistance and advice in setting ferent colors of pigments were tested with The test consists of placing a small sample up and conducting the demonstration. A carrier for triboelectric characteristics. (approximately three grams) of well schematic of the set up is shown in Fig. 3. Three colors-red, blue and green-were mixed toner and carrier in a small stainless Modifications were made to facilitate selected for the Kativo printing tests. The steel cylindrical cage. The mixing causes continuous feeding of fabric through the pigments contained in the toners were: red the toner and carrier to rub against each copiers and to allow operator control of toner-blend of Naphthol Acrylamide other and become oppositely charged. The copier functions. In addition, take-up and (C.I. Pigment Red 170) and Pyrazol cage or holder has 400-mesh stainless steel let-off rollers were added to the arrange- Orange (C.I. Pigment Orange 34, screens at its end walls. The holes in the ment. #21115); blue toner-Iron Blue 27 (C.I. screens are large enough to permit the The Xerox 2510 utilizes an optical Pigment Blue 27, #77510) and green toner particles to leave the cage, but are system in copying an original. The initial toner-blend of Iron Blue 27 and Dia- small enough to prevent the carrier parti- set up for making three-color prints used rylide Yellow (C.I. Pigment Yellow 14, cles from leaving. When dry nitrogen is three original image designs made in #2 1095). blown back and forth across the cage, the continuous loops with one mounted on The EVA materials were not commer- charged toner particles are blown away each machine, as shown in Fig. 4. This cially available with pigment and samples and the charged carrier particles remain arrangement proved unsatisfactory, as the containing Ggment could not be obtained inside. The outside of the cage will be pattern printed inconsistently. This oc- from the manufacturer. Since attempts to oppositely charged from the carrier. An curred because the images were friction produce pigmented samples via melt electrometer lead attached to the support driven and slippage occurred. The loops blending Elvax 410 and grinding and for themetal cage permits the recording of could not be made with exactly the same through spray drying pigmented EVA the electrical charge that has been stored lengths and the relative positions of the emulsions were unsuccessful (see earlier on the cage as a result of the friction loops thus changed with run time. discussions), the decision was made to between the particles of toner and carrier. The problem was solved by making one stain EVA samples using a disperse blue The polarity of the photoconductor continuous loop image that passed dye (Cibacet Blue E-GBN, C.I. Disperse drum used in the Xerox 2510 copier is through all three copiers, as shown in Fig. Blue 3) so that print locations could be positive. Thus the desired polarity to be 5. Slippage was not a problem since the observed. Although the fastness properties developed on toner for use with this copier image shifted as a unit. This arrangement of the stained materials would not be is negative. Obviously, when this occurs proved satisfactory for the demonstration meaningful, the xerographic performance the carrier particles which remain in the and for producing prints for textile testing; of the materials and the tactile properties cage after the triboelectric test will be however, it would not be acceptable for a of the prints could be assessed. Since two positively charged and the electrometer commercial machine. For commercial ap- US. Industries polyethylene-co-vinyl ace- will indicate the magnitude of that charge. plications, the operation obviously would tate resins, MU 760 and FE 532, were The results of the test is referred to as the be more complicated, with the images commercially available in the desired par- triboelectric number, and its units are produced using lasers driven by comput- ticle size (five microns), they were se- microcoulombs per gram of toner. ers. Problems involving color registration lected. The ratios of ethylene to vinyl The following types of continuous xero- would have to be addressed but should be acetate for the two materials were 82:18 graphic tests were conducted: paper toners solvable. and 91:9, respectively. on paper, using Xerox 1025 toner (red, Eight different types of carriers were green and blue) with Xerox 2510 carrier; Materials tested during this phase of the investiga- paper toners on fabric, using the same The primary materials used in this phase tion. These carriers, which were supplied developer system as in the initial runs; of the project were: paper toners compati- by Hunt Chemical and Xerox, had electri- Kativo toners (red, green and blue) on ble with the Xerox 25 10; candidate toners cal resistivities ranging from low to high fabric, using Kativo mixed with Xerox for textile applications; carriers used with values. The low resistivity carriers are 2510 carrier as the developer system; and the toners to produce developer systems used to best advantage for area printing, FE 532 on fabric, using FE 532 tinted with compatible with the Xerox 2510; and whereas the high resistivity materials are blue disperse dye mixed with Xerox 2510 additives to enhance the properties of the well suited for line reproduction. carrier. The prints made during the first developer systems. The paper toners (Xe- An additive, Cab-0-Sil, was used to three types of tests contained three colors rox 1025 toner, styrene-acrylate copoly- prevent the polymer particles from block- with regions having two and three overlap- mer) were provided by Xerox and were ing and to enhance triboelectric charging. ping colors. The last test produced single- compatible with the Xerox 2510 copier. Cab-0-Si1 is fused silica having a chain- color prints. Three colors of Xerox 1025 paper toners like structure that tends to keep the toner Several tests were performed to evalu- (red, blue and green) were matched with particles separated. ate the quality of the prints produced using carrier to produce developer systems for Thesubstratesused for the 36-inch wide xerography: wet/dry crockfastness; color-

38 GIB Vol. 23, No. 5 produced commercially on sheeting fabric similar to the fabric used for the xero- Table VI. The Effect of Cab-0-Si1 on graphicprints. After makinga straight Cut the Triboelectric Numbers for Kativo Toners and Xerox 2510 of the 50/50 polyester/cotton sheeting Carrier fabric, slides of top and side views of the fabric were taken. The magnification of the pictures varied from 25 to 50X. The Triboelectric Numbers (PC per 9) slides illustrated the details on a micro- Cam-Si1 scopic scale of the nature of flow of toner (%) materials over and into the fabric surface. Effects of fusion temperature and of Toner Color 0 1.0 1.5 2.0 crocking were also illustrated. Red +4.1 +7.0 .+6.5 +7.8 Green +2.3 +9.2 +2.9 +6.2 Results and Discussion Blue +0.6 +8.2 f9.1 +6.7 The tests to characterize the triboelectric properties of toner and carrier were useful Cab-0-Si1 was needed not only as a charge in assessing the compatibility of toner and enhancer but also as an antiblocking carrier. After the paper and textile toners agent. Without the addition of Cab-0-Sil, were tested with a number of different the FE 532 and MU 760 materials blocked carriers, Xerox 25 10 carrier was selected to the extent that sieving was impossible. for the printing tests because it gave When Cab-0-Si1 was added, the material acceptable triboelectric numbers and was could be sieved and triboelectric tests readily available. Table V gives results of performed. The triboelectric test results the triboelectric tests to assess the poten- for the EVA toners with 1% additive are tial of printing with the Xerox 1025 paper given in Table VII. The triboelectric num- toners and Xerox 25 10 carrier. The tribo- ber for FE 532 was very high (+40.5 pC electric numbers for these developer sys- pergram) withonly l%Cab-0-Sil. Sincea tems were sufficiently high that no charge higher level of additive was required to enhancer was needed. The initial continu- obtain a similar triboelectric number for ous runs were made using a composition the MU 760, FE 532 was selected as the consisting of 2% (by weight) of toner and EVA material of choice for the textile 98%of carrier. xerography tests. -, The triboelectric numbers for developer The initial continuous runs were made systems produced from red, green and blue using the Xerox 2510 paper toners and Kativo mixed with Xerox 2510 carrier are 36-inch wide white paper. The pattern given in Table VI. The effect of low definition was satisfactory but the depth of concentrations of a charge enhancer, Cab- color of large solid areas was only fair on 0-Sil, on the triboelectric number is medium shades. Solid areas are difficult to shown. The addition of Cab-0-Si1 at a print with the Xerox 2510 copier since it lefel of approximately 1% on weight of was designed to be a blue print (line) toner was needed to obtain sufficiently copier; Le., the toner delivery system on high triboelectric numbers for successful the copier was not designed to deliver large printing on the polyester/cotton sheeting quantities of toner required for printing fabric. Higher levels of Cab-0-Si1 were solid regions. not used because the triboelectric numbers The next step involved using the paper were not appreciably changed with in- toners to print on fabric. The pattern creasing concentration. Also, toner prop- definition was acceptable but the depth of erties can be negatively affected by high shade again was only fair. In an effort to levels of additives. For the initial runs, the improve the depth of shade, the concentra- Kativo toners were sieved to a particle size tion of the paper toner in the developer of approximately 45 microns and pre- mixture was increased to approximately mixed with Cab-0-Sil. The developer 3% by adding toner to the developer tray. system consisted of 2% (by weight) of the The depth of color was improved without a toner mixture and 98% of the Xerox 25 10 sacrifice in pattern definition; however, carrier. results were not consistent from shade to Tests with theEVA toners revealed that shade. The shade of color in decreasing

Table VII. The Effect of Cab-0-Si1 on the Triboelectric Numbers for Two U.S. Industries EVA Toners Stained with Disperse Dye

Triboelectric Numbers bC per g) Cab-0-Si1 (%) Toner 0 0.5 1.0 1.5 2.0 5.0

~ FE 532 - +2.7 +40.5 +39.9 +18.8 +38.2 MU760 - - +5.6 - f17.5 -

39 Color Xerography toner. Since the elastic properties of the control the Kativo toner at the higher toner could not be changed, efforts were concentration. One possible reason was made to adjust the oil release fluids and that the Kativo toner was not as well fuser drum temperature. matched with the carrier as the paper order of depth was green, red and blue. The wiping mechanism of the fuser toner, as indicated by the triboelectric Since this was the order in which the assembly applies oil to the fuser drum to numbers. Another was the Kativo toner printing was conducted on the continuous aid release of molten toner. Examination particles were too large. The Kativo toner line, it was hypothesized that the fabric of the wiping mechanisms revealed that had been sieved using a mesh screen with was being dried during contact with the the wicks were coated with polymer, im- openings of approximately 45 microns. fuser drum, changing the fabric’s dielec- pairing lubrication. Replacing the old The screen selection was based on infor- tric properties. As a result, less toner was wicks with new wicks loaded with oil mation in the literature indicating accept- being picked up in subsequent copiers. improved the short term wiping perfor- able toner particle size ranged from 5 to 45 However, in tests with moist air forced mance of the mechanism, but toner microns. However, according to xerogra- across the fabric between the copiers, the quickly built up on the wicks, hindering phy experts, the typical range of toner shade did not change significantly, Micro- subsequent wiping. Obviously, modifica- particle size is from 5 to 20 microns. scopic examination of the printed areas tions to keep toner on the substrate would Samples of each of the three Kativo indicated that increased deposition of be preferable. Noncontact approaches to toners were sent to a laboratory for parti- toner would darken the shade. The con- fixing the toner could be used; however, cle size analysis with a Coulter Counter. centration of toner was increased to ap- developing a new system for fixing toner on The mean particle size for the green, blue proximately 4% and a run was made. The the Xerox 25 10 was beyond the scope of and red Kativo toners were 18,32 and 5 1 color was darker but the inside of the the project. microns, respectively. The percentage of copier was covered with toner. At this level Another factor contributing to the off- the particles falling in the desirable range of toner, the carrier was not able to control setting problem was that the fuser temper- was41,17 and6forthegreen, blueandred it and considerable dusting occurred. ature was set too high. The fuser roll toners, respectively. The particle size was In the next series of tests, the Kativo temperature on the Xerox 2510 could be indeed too large for good xerographic toners were used to print on fabric. Based set between approximately 120 and 160C. performance. on the results with the paper toners, a 3% This was too high for Kativo toner which The toners were then air milled to toner concentration was used. In theinitial has a melting point of approximately 95C. reduce the particle size. Due to time runs, large regions of heavy toner deposi- The Xerox 2510 copier was modified to contraints of the project and the unavail- tion resulted in streaking on the fabric, allow lower fuser roll temperatures to be ability of a mesh screen with openings especially with the red Kativo. “Echo” used. For settings at and below 9OC, “cold smaller than 45 microns, the ground toner images were observed as faint repeated offsetting” was observed where toner was was collected, sieved and loaded into the images printed behind a designated pat- not completely fused onto the fabric or the copier. Evidently, the particle size had tern. In addition, excessive dusting of fuser drum. When fuser temperature was been reduced since the prints were greatly toner inside of the copier was noted. increased above lOOC, hot offsetting wors- improved, with better print quality and The problems encountered with the ened with increasing temperature. The depth of shade. Also, when toner concen- Kativo toners were discussed with repre- test results indicated that the optimal tration was increased to 3%, dusting of sentatives of the Xerox Engineering Corp. temperature for minimizing offsetting was toner inside the copier was reduced. The They advised that the echo images ob- about 1OOC. higher toner concentration gave darker served in Kativo prints were likely caused Since excessive dusting of toner inside prints. by a toner fusing problem known as “hot the copier had occurred when toner con- After all the process development offset.” This phenomenon occurs when the centration was 3%, carrier was added to changes were made, a printing run was toner is not elastic enough to “snap back” the developer system to reduce the toner conducted where polyester/cotton fabric to the substrate from the fuser drum. On concentration to approximately 2%. Prints was printed using the three colors of subsequent revolutions of the fuser drum, at this concentration wereof better quality Kativo toner. Although the offsetting the toner left on it is deposited on the but were light in depth of shade. Increas- problem was never totally eliminated, substrate, resulting in faint ghost images. ing toner concentration back to 3% re- three-color prints (including two and Factors that can contribute to hot offset- sulted in hot offset of toner and a return of three-color overlap regions) suitable for ting include lack of oil release on the fuser the dusting problem. Although the carrier testing the textile properties of Kativo drum, too high a temperature for the fuser was able to control‘the paper toner at a were produced. drum and poor elastic properties of the concentration of 3%. it was unable to The results of the textile property tests

I Table VIII. Results of Fastness Tests for Prints with Kativo Toner I Crockfastness’ Launderingb ChlorineC Drycleaningd Light’

Color ’ Color Color Specimen Dry Wet alning Change Staining Change 20 hr 45 hr 65 hr Kativo Toner RED 4 5 5 5 5 5 5 GREEN 4-5 5 5 5 5 3-4 3 BLUE 5 5 5 5 5 4-5 4 2-COLOR 4 4 5 5 5 4 4 3-COLOR 4 4 5 5 5 4 4 Screen Print‘ BLUE 5 4-5 5 5 BLACK 4-5 3 5 5 - RED 4-5 3 5 5 aAATCC Test Method 116-1983. bAATCC Test Me Test Method 61-1986, Test No. 5A. dAATCC Test Method 132-1985. eAATCC Test Method 16E-1979. ‘Produced by a I

40 033 Vol. 23, No. 5 re summarized in Table VIII. The flam- better xerographically than Kativo toner ty test results indicated that no Table IX. Stiffness of Kativo Prints and caused less stiffening of the fabric. cant difference existed in the flam- Unfortunately, the unavailability of pig- tivo printed samples and Flexural Rigidity mented EVA left many questions unan- The crockfastness re- 0-w" swered. the Kativo toners were Specimen Mean SD' A copier should be developed specifi- compared to control, 1-Color 354 132 cally for printing fabric. The demonstra- was screen printed fabric obtained 2-Color 365 124 tion was conducted using the Xerox 2510 leading sheeting manufacturer, the 3-Color 352 196 copier, designed specifically for line print- Control 194 20 ivo toners exhibited slightly higher - ing on paper in a batch mode. Information rockfastness test. The aThe large deviations between values resulted for producing the copies was fed in opti- of the Kativo prints to laun- from inconsistent coverage of Kativo patterns cally. A copier for printing textiles would ne and drycleaning was ex- along the specimen length. be different since it must operate continu- the exception of the green, ously at speeds up to approximately 50 ess of the Kativo prints to The FE 532 material, stained with yards per minute. Information storage and s acceptable but inferior to the disperse dye, also had excellent fiber wet- input for image formation should be ac- control. Since the red Kativo print was ting properties. The cross-sectional view complished using a computerized system rated excellent after 65 hours of exposure, indicated a complete penetration of the which would facilitate fast style and color the problem with the green should be fibers. The thickness of the deposited changeovers, as well as aid in the produc- solvable by changing pigments. material appeared to be less than for the tion of new designs. Since different pig- The results of flexural rigidity tests are Kativo toner. ments affect the dielectric and triboelec- shown in Table IX. The stiffness of the The control fabric, which had been tric properties of the toner, each colored Kativo printed fabric was much higher screen printed in a commercial process, toner must be tailored for the copier in than for the control. Thus the stiffness of was also examined under the microscope. which it is to be used. Since a range of the Kativo film is a potential problem that The wetting and penetration were similar colors would be needed for most fabric should be further studied. to those observed for the Kativo and FE printing operations, the production of a Since the triboelectric number for FE 532 toners. toner for each color would not be feasible. 532 (EVA) toner was very high with only Thus the commercial textile xerographic 1% Cab-0-Si1 additive, it was selected Conclusions and Recommendations printing system will likely utilize three over MU 760 toner for producing xero- The use of xerography for printing fabric primaries plus black, as currently incorpo- graphic prints. The FE 532 toner which appears to be technically feasible; how- rated in color paper xerography to produce had been stained using blue disperse dye ever, the successful commercialization of thousands of shades via overlap printing: was loaded into an unmodified Xerox 25 10 xerography for printing fabric will require mauve, cyan and yellow with black. The copier and prints were made. Colorfast- further fesearch to develop textile toners production of color using three primary ness tests were not performed on the prints yielding darker shades. A prototype copier toners should be studied. because a commercial toner would contain designed specifically for printing fabric pigment, not disperse dye, and thus the should be developed. Acknowledgements colorfastness of the toner stained with Two potential textile toners have been The research reported in this paper was disperse dye would not be meaningful. The identified. Further research on both of funded by the Office of Industrial Pro- FE 532 toner outperformed the Kativo these materials is needed before commer- grams of the U.S. Department of Energy toner xerographically. Although the cialization of the textile xerography pro- and its support is gratefully acknowl- pints were light in color, due to the small cess. Although the Kativo toner (a modi- edged. Special thanks are due to Robert amount of disperse dye absorbed by the fied epoxy which is a thermoset) appears to Massey and Bill Sonnett, DOE project toner, the clarity and definition of the have promise as a textile toner, work is monitors, for their advice, guidance and prints were superior to those produced needed to improve it in several areas. The support throughout the project. The using Kativo toner. Also, the aesthetic flow characteristics of the modified epoxy DOE/Georgia Tech Industrial Working properties of the prints were qualitatively sould be changed to eliminate the offset- Group for the project was very helpful and judged superior to the Kativo prints. ting problem. One approach might be to generous with its time, advice, materials, The results of the optical microscopic increase the size of the oligomer which supplies and equipment. Its support is examination revealed that the wetting and would change the flow characteristics of gratefully acknowledged. Elisha Shep- penetration obtained with the Kativo and the material at the melting temperature. hard, research associate, conducted much FE 532 toners were similar to those Another approach to solving the offsetting of the research to identify binders and obtained with conventional printing. Pho- problem is to change the fixation process to textile toners. Her efforts are gratefully tographs taken of the xerographic prints 1 noncontact system. Darker shades than acknowledged. We wish to acknowledge produced using paper toners showed that Lhoseobtained will be needed. Different the assistance and hard work of a number the individual toner particles, although 3igment types and loadings should be of textile engineering students: Brian adhering to the fabric, do not wet the :xplored. The effects on color shades as Failor, Craig Johnson, Leighton LeBoeuf, individual fibers. Similar results were ob- #ell as on triboelectric numbers should be Allen Pendergrass and Marla Wcinberg. tained for several types of paper toners studied. Kativo toner particle size should including toner for the Haloid system and m beoptimized, which should improve tribo- References three colors of Xerox 1025 toner. In these electric numbers and allow darker shades cases, there was no penetration of the toner to be produced. Once the toner is opti- (I) Cook, F L , et al , Application of Chemicals material into the interior of the fibers. In mized, xerographic prints should be pro- to Substrates Without the Use of Liquid, Solid- contrast, the wetting of fibers by the on-Solid Processing, Funded by the Office ot Indus- duced and compared aesthetically with trial Programs of the U S Department of Energy, FI- Kativo toners of all three colors was control prints produced via screen print- nal Report, Augubt 1990 excellent. The toner material was observed ing. (2) SchaRert, R M , tlectrophotographr. The on top of the fabric as well as in the cut Further work with the EVA (polyethyl- Focal, London. 1965 region. With heavy toner concentrations, ene-co-vinyl acetate) toner should be con- bridging of the spaces between fibers was Author's Address ducted. The results of the current study Dr. Wallace W. Carr. School of Textile Engineering, indicated that the EVA toner behaved Georgia lnstituteofTechnology, Atlanta,Ga. 30332

41 -A -N D COLORIST TEX1ILE C:HEMISTS AND COLOlVSTS

May 1991/Vol. 23, No. 5 ISSN 0040-490X

"1 Features

8 AATCC Council Highlights The 323rd meeting of the AATCC Council was held February 14 in Charlotte.

15 OLNEY MEDAL ADDRESS Analysis of Flnish Distribution on Textile Substrates b by Hans-Dietrich Weigmann, Textile Research Institute The author discusses two methods developed at TRI for determining finish distribution on fibers and yarns: liquid membrane wettability scanning and microfluorometry.

25 IMPROVED DY EABl LlTY Finishing with Modified Polycarboxylic Acid Systems for Dyeable Durable Press Cottons by Eugene J. Blanchard, Robert M. Reinhardt and B.A. Kottes Andrews, U.D. Department of Agriculture This study investigated the finishing of cotton fabric with polycarboxylic acids and reactive hydroxyalkylamine additives to determine if dyeable ester-crosslinked fabrics could be produced.

29 COMING BACK Piece Dyeing Rayon and Rayon Blends by G. Robert Turner, Consulting Editor While rayon all but disappeared from textiles during the last 30 years, it has begun to reappear, primarily in women's wear. This review is for those who have not had extensive background with the fiber.

33 IN COLOR Printing Textile Fabrics with Xerography by W. W. Carr, F. L. Cook, W. R. Lanigan, M. E. Sikorski and W. C. Tincher, Georgia Institute of Technology A new technology is needed for fabric printing that will permit frequent style and color changes with minimum downtime for changeover and will allow computer storage of design information. Xerographic printing has the potential of meeting these requirements.

Departments 6 News 48 Cumulative Index 42 People 50 Employment Register 44 New Products 53 World Textile Calendar 46 Membership Applications 54 AATCC Calendar

THE COVER: This rugged little pier doesn't look like it belongs on a deserted island, but that's where Claudia Deaton found it with her camera. Portsmouth Island, which has been abandoned nearly 20 years, is midway between Cape Hatteras and Cape Lookout on North Carolina's Outer Banks. Claudia is AATCC's newest staff member, signing on in January as a laboratory technician.

IF YOU HAVE A PHOTO YOU THINK WOULD MAKE AN APPEALING COVER. PLEASE LET US HEAR FROM YOU