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Disperse Dyes: A Dye Chemist's PerspectiveBy Max A. Weaver, retired from Eastman Kodak Co., Kingsport, Tenn.

The history of disperse dyes is inseparable fromthe development of the new man-made, hy-drophobic fibers that required the new dyeclass to be developed. When cellulose acetate,the first hydrophobic fiber, was developed inthe 1920s, the existing hydrophilic dyes thathad been used for the natural fibers were notsuitable for dyeing the new material. Some lim-ited success was achieved using some simpleaniline azo dyes containing sulfomethyl groupsthat would hydrolyze in the dyebath to yieldthe free base under certain pH conditions.However, the disperse dye industry actuallybegan when some British companies discov-ered that grinding water-insoluble dyes withsurface active agents provided an aqueouscolloidal dispersion when combined with wa-ter. For the next 25 years, the new dyes weresimply called "acetate dyes." However, in the1950s, new developing fibers such as polya-mides, polyesters, triacetate, acrylics, andmodacrylics resulted in the name change to"disperse dyes" in 1953, in view of the upcom-ing 2nd edition of the Colour Index in 1955.'

E A R L Y D I S P E R S E D Y E

H I S T D R Y

New FibersAlthough textile dye chemists made great ad-vances in the 1950s by providing dyes for ac-etate with improved properties such as fast-ness to light, gas (oxides of nitrogen), washing,etc., the introduction of the new fibersbrought even more stringent and differentproperty requirements for disperse dyes. Poly-esters, polyamides, and triacetate requiredhigher dyeing temperatures than acetate,which necessitated using dyes with excellenthydrolytic stability over rather wide pH ranges.Polyester dyes needed resistance to sublima-tion for fabric pleating, ironing, heatsetting,etc. The dry heat Thermosol dyeing processrequired dyes with outstanding thermal stabil-ity and fastness to sublimation. Durable pressfinishes on polyester/cellulosic blends requireddyes that would not change shade in the pres-ence of various harsh resin catalysts, includingacidic metal salts. Polyester/wool blends re-quired dyes that gave little staining on wool orat least stains that could be removed.

The introduction of textured filamentspolyesters, which found widespread use in ap-parel fabncs, required bright dyes with excel-lent pH and hydrolytic stability because of dye-ing temperatures up to 275F. Also, thepreferred dyes showed little or no sensitivity indye uptake to the heat history of the texturedpolyesters. Disperse dyes for polyamide carpet

required excellent lightfastness, resistance to"Gulf Coast" fade, and stability to pH as highas 8-9 to decrease the staining of nylon withthe oils in the jute backing.

Hydrophobic FibersAlthough not complete, the previous list of dyeproperties is enough to establish that muchwork was needed to satisfy the dye require-ments for the developing fiber markets in the1950s. Furthermore, by the 1960s, there wastremendous grov\/th in the production of thenew hydrophobic fibers (Table I). Grov^h in thesecondary cellulose acetate fiber market hadleveled off, but polyesters and polyamidesshowed strong growth with further growthpredicted. These facts encouraged existing dyesuppliers to increase research efforts and addi-tional companies to enter the lucrative market.

Dye ProducersThe late 1960s and 1970s brought the researchand patenting efforts to new heights as shownby the U.S. patents on new disperse dyes andthe increased number of dye producers. Be-tween 1955 and 1971, the number of dyeproducers listed in the Colour Index more thandoubled from 21 to 44. In the meantime, manymajor disperse dye producers built extra capac-ity in anticipation of continued rapid growth.By the 1980s, however, a number of factorsinitiated the demise of the U.S. textile dye in-dustry including over capacity, increased num-ber of imported dyes, decline in the overall U.S.textile business, increased costs for waste dis-posal, and implementation of TSCA and in-creased levels of toxicity testing for new dyes.New textile dye research in the United Stateshad essentially stopped and textile dye chem-ists were an endangered species.

C H A L L E N G E S I N D I S P E R S E

D Y E C H E M I S T R Y

Historical ResearchSeveral challenges are immediately evidentwhen creating new dyes with some improve-ment in properties that can be sold profitablyin the marketplace. First, the dye chemist mustbe somewhat familiar with what has beendone historically by other workers. At Eastman,this was done by obtaining copies of the U.S.patents (as well as some foreign patents) ondisperse dyes that resulted in a patent librarythat began about 1930. They were then ar-ranged into classes and subclasses for the mostwidely researched chromophores such as azo,anthraquinone, methine, o-nitroarylamine, anda variety of miscellaneous chromophore

classes. This allowed a quick review of knownchemistry for specific structure types.

Second, the researcher had to become fa-miliar with the dye chemistry that had beenpursued within his/her present company. Thiswas best accomplished by timely and detailedtechnical reports on dye preparation andproperties.

Third, the disperse dye chemist needed tobecome knowledgeable about structure prop-erty relationships, particularly the all-importanteffect of structure on color.

Finally, since most dye companies benefitedgreatly by having patent protection on theirnew dyes, an understanding of the inventionand patenting process was very helpful.

New IdeasNew ideas are the life's blood for the re-searcher, and the invention criteria are utility,novelty, and non-obviousness to one skilled inart. My 44 years as a dye researcher led to theobservation of several truths regarding inven-tion. New ideas, and hence inventions, cannotbe planned, scheduled, or directed. However,they can be encouraged and facilitated by anenvironment of free thought, hard work, andattention focused on the problems that needto be solved. Communication and discussionof ideas with fellow workers stimulate addi-tional ideas. If not put to practice, even the

TABLE 1.

Fiber Production in Million of Pounds^

Fiber 1950Acrylics and modacrylics 9Cellulose estersPolyamidesPolyestersPolypropylene

4409000

19663534541,066485133

^ Private survey for Eastern ChemicalProducts Inc.

TABLE II.

Number of TextileEastman through

ColorYellowOrangeRedBlueBrownBlackNo dye''Total

Dyes Produced at1986

No. of Dyes14.97911,07627,11230.00910,0489213,17997,324

^ Represents colored compounds thatdecomposed during the dyeing process.

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best ideas are useless. The dye chemist mustdevelop the skill of defining the invention andrecognizing what advantages are inherentwhen compared to the available prior art.

The information needed by the textile dyechemist must be generated empirically, nottheoretically. This means that with the vastnumber of colored compounds provided byorganic chemistry, the dye chemist can, andseems obligated to, prepare what seems to bean almost unlimited number of dyes for evalu-ation on various fabrics. To get some idea ofthe effort involved in doing research on dis-perse dyes, it is noted that work on acetate/disperse dyes started in 1934 at Eastman andcontinued until the dyes business was sold toCiba-Geigy in 1986. Table II shows that over54 years, more than 97,000 different dyeswere prepared and evaluated. The "no dyes"category represents colored compounds thatdecomposed during the dyeing process.

Dye EvaluationNot only did a large number of different dyeshave to be prepared, but evaluation methodswere needed for screening the dyes that weremade in the laboratory in about 0.5-3.0 gquantities. The dyes were then dyed at twolevels on cellulose acetate, polyesters, andpolyamides, allowing preliminary testing forbasic properties such as fastness to light, sub-limation, washing, etc. If a dye had attractiveproperties, larger scale and more completeproperty evaluations ensued. Small structuralchanges sometimes made significant differ-ences in fastness and performance properties,and even different isomers and homologuesusually showed some differences.

The early dye researchers at Eastman estab-lished a very convenient system for storing andretrieving the small dye samples that have beenin place from about 1934 to the present. Thesesamples have been very valuable for non-tex-tile uses such as dyes for dye diffusion thermaltransfer, imaging for photography, and ther-mally stable reactive dyes for copolymerizationinto polyesters and polyurethanes.

Dye evaluation is complicated by the factthat dyes perform differently on different fi-bers. To discuss fastness of a dye, one mustactually refer to the dye fiber substrate. Forexample, dyes that may have outstandinglightfastness on cellulose acetate, and polyes-ters may have poor fastness on polyamides andvice-versa. Historically, accelerated testing hasbeen used to try to simulate actual long-termperformance. Here the dye chemist becomesappreciative of associations such as AATCC fortheir interest in developing some standard testmethods that are at least agreed upon by someexperts in the field.

Summary of Structure TypesHistorically, disperse dyes were selected mostlyfrom anthraquinone, azo, methine, o-

cliazolize

Lower energy I Higher energy II

Fig. 1. 4-aminoazobenzene dye structure.

nitroarylamine, quinophthalone, and a fewmiscellaneous classes. The azo class received byfar the most attention, with anthraquinonebeing a strong second. Azo dyes have the ad-vantage of color strength (high extinction co-efficient), ease of manufacture, and economy.They also provide an entire gamut of colors.Even though the anthraquinones have lowercolor value and in general are more expensive,they continue to dominate certain parts of themarket because of their bnghtness and com-bination of lightfastness and dyeing properties.

The most useful anthraquinone dyes havesubstituents in the alpha positions of the nngsystem and are usually denved from interme-diates made by sulfonation of the an-thraquinone ring in the presence of mercurysalts, which provides alpha substitution asopposed to beta substitution. Mercurywastes have created pollution problems andproper disposal has added costs. Also, reac-tions for synthesizing anthraquinone dyesnormally require an organic solvent that mustbe recovered or disposed of without harm tothe environment. Many azo dyes are pre-pared in aqueous media with only acids andbases required.

The other three dyes classes provided mostof the yellow dyes, with the methine structuresproducing extremely bright yellow shades withexcellent lightfastness. Some of thequinophthalones have become workhorse col-ors because of their excellent lightfastness anddyeing properties. Several o-nitroarylaminesfound their place with some of the bestlightfastness available on polyester and cellu-lose acetate. They are economical, but sufferfrom low extinction coefficients. Recent effortsto develop new chromophores for dyes andcolorants have been summarized.^

From 1965-1985, much research was di-rected toward azo dyes for polyester to replacethe brilliant, but tinctorially weaker and moreexpensive anthraquinone dyes. Three impor-tant red anthraquinone dyes were the ancientC.I. Disperse Red 60 and two of its more sub-limation fast derivatives, C.I. Disperse Red 92

and C.I. Disperse Red 159.''* The bright blueanthraquinones were best represented by neu-tral blues C.I. Disperse Blue 56 and C.I. Dis-perse Blue 73 as well as the bright, but veryexpensive turquoise C.I. Disperse Blue 60. ̂ '̂The latter had the valuable property of flaringgreener under incandescent light compared todaylight, in addition to having excellentlightfastness. The intense research effort toimprove the brightness and lightfastness of thered and blue azo dyes has been documented.^

Heterocyclic azo dyes derived fromdiazotizable heterocyclic amines have beenwidely investigated and reviewed because oftheir brightness and high extinction coefficientsas well as the azo dyes derived from hetero-cyclic coupling components.^'"

D Y E C H E M I S T S AT W O R K

Dye ImprovementsAnother summary is not required since excel-lent reviews of disperse dye chemistry areavailable.'^"•'^ However, it is desirable to givea couple of examples of innprovement in theproperties of disperse dyes that have resultedfrom research efforts of dye chemists. Manyof the early orange to violet azo dyes wereof the 4-aminoazobenzene structure (Fig. 1).This structure type has been one of the mostwidely investigated azo dye structure be-cause of its versatility in color and availabil-ity of intermediates.

The entire color gamut from yellow togreenish-blue can be achieved by varying thesubstituents on Rings A and B and on the cou-pler nitrogen atom. The substituted anilinesand the substituted aniline couplers are reason-ably cheap, and the coupling reactions usuallyproceed in high yields. Several reviews relateto the effect of substituents on color in the 4-aminoazobenzene structure.'^"^^ Mos* ^f theearly orange to bluish-red azo dyes I :ellu-lose acetate and later for polyesters thisstructure. The yellows were not rep' -fg^jsince the dyes were phototropic unle /^

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NHAcyl

Acyl = COR4, CO2R4 and SOjR^, wherein

R4 = optionally substituted alkyl, cycloalkyl, aryl, etc.

Fig. 2. Hydrogen bonding in chromogen.

contained at least one group with strong elec-tron-withdrawing properties that shifted fromyellow to orange. The phototropism problemin yellow azo dyes was solved by replacing thesubstituted aniline couplers with heterocycliccouplers such as pyrazolones, indoles,pyridones, etc.

The nitro group in the 4-position on theazobenzene structure was usually desired be-cause of the significant shift in the visible ab-sorption band to longer wavelengths(bathochromic shift) and the accompanyingincrease in lightfastness on cellulose acetateand polyesters. Several observations on theeffect of substituents on color in the 4-aminoazobenzene system were made. Nega-tive groups in the 2-, 4-, and 6- positions inRing A give the maximum bathochromic shiftin the visible absorption band. Usually threestrongly electron-withdrawing groups are re-quired to produce blue dyes. Also, the absorp-tion maximum in the visible spectrum is depen-dent upon the basicity or electron density ofthe aniline coupling component. The presenceof alkyl, cycloalkyl, and aryl groups for /?, and/?2 provide bathochromic shifts as compared toff, and /?2 equal to hydrogen. Negative sub-stituents on /?i and R2 give shifts in the absorp-tion band (hypsochromic shift) to shorter wave-lengths with usually an accompanying increasein lightfastness on cellulose acetate and poly-esters. Electron donating groups such as alkyland alkoxy in Ring B, particularly in positions2- and 5- provide bathochomic shifts, but un-fortunately sometimes at the expense oflightfastness.

These effects may be explained theoreti-cally by the valence-bond resonance approach(Fig. 1). In donor-acceptor chromogens such as4-aminoazobenzenes, the absorption bandmay be accounted for by the different energylevels of structures I and II, with II being thehigher energy level. Bringing the energy level

JANUARY 2OO3

of II closer to I moves electronsfrom the coupler nitrogenthroughout the conjugated sys-tem to the electron-withdrawinggroup in Ring A at lower energylevels, thus requiring longerwavelength light. High-energystructures in II are stabilized byelectron-withdrawing groups inRing A and electron-donatinggroups in Ring B, which decreasesthe difference in energy betweenstructures I and II.

Effect of m-Acyl-amino GroupsThe discovery of an acylaminogroup in the 2-position of Ring Bin the 4-aminobenzene dyes wasone of the most significant ad-vances in disperse azo dyes andwas an area that received muchattention by dye chemists from

the 1960s to the 1980s (Fig. 2). The presenceof the 2-acylamino group would be expectedto cause little or no effect on color because itbasically neither donates nor withdraws elec-trons according to the Hammett values. Sur-prisingly, however, the group gives a notablebathochromic shift, which has been used veryadvantageously by dye chemists. The effectmay be explained by considering the stabiliz-ing influence of the acidic hydrogen that pro-vides hydrogen bonding and stabilization ofthe polarized state, thus lowering the energyrequired in the absorption of light and a shiftto longer wavelengths.

This theory is supported by the fact thatwhen the hydrogen in the acylamino group isreplaced by an alkyl group, such as methyl, thegroup behaves exactly as a group having aHammett value of about zero should have andshows little or no effect on color. Fortunatelyfor the polyester dye chemist, thebathochromic shift was usually accompaniedby an increase in fastness to light, sublimation,and washing without significant loss in dyeingproperties when compared to the same dyeswhere R was hydrogen,alkyl, and alkoxy. Also, insome cases the visible ab-sorption bands were nar-rower, which resulted inbrighter dyes and some-times an increase in ex-tinction coefficient andcolor strength.

C.I. DisperseBlue 79C.I. Disperse Blue 79,commercialized by Sandozin the 1960s, was the firstazo dye containing a m-acetamido group to

achieve widespread use (Fig. 3).̂ ^ This dye andits homologue, where Rs was methyl, were bothsuitable for producing navy and black shades forpolyesters. The combination of the negativegroups on the diazo component and the com-bination of the 2-acetamido groups with the 5-alkoxy groups provided the blue color. The N,N-bis(acetQxyethyl) and acetamido groups addedfastness to light, sublimation, and washing. Thisdye type quickly replaced the more expensiveanthraquinone dyes of the day because ofeconomy and properties for making navy andblack shades.

This discovery spurred dye chemists to pur-sue azobenzene dyes containing acetylaminogroups in order to produce a variety of newdyes in addition to the navy blue types. Fig. 4shows some of the azo dyes for polyester thatwere commercialized in the late 1960s and1970s. This type of dye resists shade changeswhen acid catalysts are used to cure durable-press resins. These dyes illustrate how dyechemists have modified structures to improvefastness to sublimation that is dependent onthe difussion coefficients of the dye in the poly-mer substrate. Fastness to sublimation usuallyincreases as the molecular mass and/or thepolarity of the molecule increases. Thus, thelarge phenyl groups and the polar groups suchas ester, ether, acylamino, and dicarboximideall increase fastness to sublimation.

The effort to prepare bright blue 4-aminoazobenzene dyes was hindered in theearly years because the highly negatively sub-stituted anilines needed to produce bright blueshades were difficult to prepare and the dyescould not be prepared in high yields by directdiazotization and coupling because of the in-stability of the diazonium salts. This problemwas overcome when Bayer dye chemists dis-covered that cyano groups could be introducedin the 2- and 6- positions by replacing halogensusing metal cyanides.^^ This displacementmade these dyes economically attractive andproduced bathochromic dyes with improvedlightfastness and sublimation compared to thehalogen substituted intermediate dyes. From acommercial perspective, the dyes from 2-

\ ^

R5

R5

NO,

Br

= ethyl.

N-

C.I.= methyl, C

OR3

NHCOCH3

Disperse Blue 79.1. Disperse Blue 79:1

Fig. 3. Large volume blue azo dyes

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NHC0CH3

Rj = benzyl, C.I. Disperse Orange 136 "Rj = ethyl, C.I. Disperse Red 210 "

NHCOCjHj

, = H, C.I. Disperse Red 7 4 "« = Ci, C.I. Disperse Red 167 »

C.I. Disperse Red 140"

NHCOCH3 N

= H.C.I. Disperse Red 3 0 7 "= Ci. CI. Disperse Red 305 "

NHCOCH.,

Rj = benzyl, C.I. Disperse Biue 316 "Rj = ethyl. C.I. Disperse Biue 165:1 ^

NHCOCH.,

J = ethyl, C.I. DisperM Blue 165 "Hj. CI. Disperse Blue 337 »

NHCOCjHj

C.I. Disperse Blue 338 ^'

Fig. 4. Typical 2'-acylamino substituted azobenzene dyes.

bromo-4,6-dinitroaniline and 2,6-dibromo-4-nitroaniline received the most attention. Fig. 4shows some of the bright blue to greenish bluedyes that were developed and sold to competewith the expensive C.I. Disperse Blue 73 andCL Disperse Blue 60 for some end uses. Theadvantage in color value of the azo dyes canbe appreciated by noting that two of the azodyes, C.I. Disperse Blue 337 and C.I, DisperseBlue 338, have extinction coefficients of72,000 and 73,000, respectively, which ismore than three times that of the typical blueanthraquinone dyes.

The blue azo dyes had excellent fastness tolight, sublimation, and washing, but still suf-fered in dyeing properties when compared tothe anthraquinones for exhaust dyeing. Tohelp the dyeability of Cl , Disperse Blue 165,the dyes from a mixture of /\/,A/-diethyl- andA/,W-di-n-propyl-m-acetamidoaniline couplerswere utilized.^^ Disperse Blue 338 with thecyclized 1,2,3,4-tetrahydroquinoline couplerwas a bright, greenish-blue dye capable of re-placing Disperse Blue 60 in several combination

shades with its ability to flare green under in-candescent light when compared to daylight.Unfortunately, its use was limited to thethermofixation method of dyeing primarily.

Heterocyclic Azo DyesIntense research was done on heterocyclic azo

dyes to replace anthraquinone dyes withbrighter and more lightfast azo dyes (Fig. 5).This research in the 1960s and 1970s wasspurred by the discovery of the brilliant blueazo dyes for cellulose acetate from 2-amino-5-nitrothiazole; for example, Cl . Disperse Blue102, by J. B. Dickey, et al., at Eastman.^" Thedyes had only moderate lightfastness but werevery strong and had excellent fastness to gasand very good dyeability. Also, some red azodyes from certain substituted 2-aminobenzothiazoles, such as 2-amino-6-methylsulfonylbenzothia-zole, were useful onboth cellulose acetate and polyesters in the1950s, but still lacked the brightness andlightfastness to compete with the bright redanthraquinones.

A few of the red-pink heterocyclic azo dyesthat were commercialized in the 1970s had thenecessary brightness, lightfastness, and colorvalue to compete with some of the expensiveanthraquinone red dyes are shown in Fig 5. Thedyes from 2-amino-5-ethylthio-l ,3,4-thiadiazolediazo component and aniline couplers contain-ing m-acyiamino groups, such as acetamido,had a very desirable combination of brightness,lightfastness, and color value. C.I. Disperse Red338 has an extinction coefficient of 55,000 (li-ter mol'' cm'^), while most of the competitiveanthraquinone dyes have extinction coefficientsin the 13-14,000 range, thus indicating that theazo dyes were about four times as strong.^ C.I.Disperse Red 340 had better lightfastness andleveling properties on polyamide carpet thanthe other two red dyes, making it a competitorfor the expensive C.I. Disperse Red 55 and 55:1,which were widely used for polyamide carpetin the 1970s and 1980s. The green dye, C.I. Dis-perse Green 9, which was a product from thehighly researched Gewald synthesis of substi-tuted 2-aminothiophenes of the 1960s, had aunique shade and could be used as a green flar-ing dye under incandescent light for flare con-trol. However, its use was limited because ofmoderate lightfastness. Some of these dyes of-fered the dyer and finisher tr̂ emendous savingswithout a compromise in properties while pro-viding a reasonable return on investment fordye manufacturers.

,,.-N

NHCOCH.,

C.I. Disperse Red 338 C.I. Disperse Red 339

NHCOCH3

C.I. Disperse Red 340 •"

NHCOCH3

C I. Disperse Green 9 '

Fig. 5. Heterocyclic azo dyes.

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C O N C L U S I O N

The golden years of the 1960s and 1970s fordisperse dye research brought an array of newdye structures that were designed to meet adiversity of needs on a variety of hydrophobicfibers. Problems in the U.S, textile and dyebusinesses in the 1980s brought much textiledye research in the United States to a halt.Mock recently prepared a comprehensive re-view of the U.S. textile dye industry.^^"^^

During the 1990s, the larger European dyesuppliers continued research at a decreasedlevel, but have recently faced hard times dueto extreme competition from low-cost dye pro-duction in China, India, and the Pacific Rimcountries. This has resulted in dye lines beingstreamlined with many companies undergoingmergers, consolidations, reorganizations, spinoffs, etc. Any observer in the field of textiledyes is aware that research has essentiallystopped and the world's dyes business contin-ues to rest on the outstanding work of previ-ous years.

What does the future hold for U.S. dyemanufacturers? The picture certainly does notseem to be a pretty one. Some innovativecompanies have continued making non-textiledyes for various end uses such as dye diffusionand wax thermal transfer for non-silver halidephotography, lasers, biomedical applications,color filters, non-linear optics, solar cells, elec-trophotography, ink jet pnnting, etc. However,the current markets are small and uncertain.Polymeric dyes for coloring thermoplasticshave also attracted some research effort.

Without any attempt to be prophetic, onemust presume that things will not stay thesame and free world trade will result in somesort of equalization. There may well be furtherinnovation in textile fibers that cannot be col-ored with existing dyes as has happened pre-viously. If new innovation is needed in dyetechnology and the United States remains asovereign, free, innovative nation, the U.S.dyes business might again "rise from the

ashes" as it has twice previously after twoworld wars. In the meantime, some of us havefond memories of the "good old days" and areproud and thankful to have been a small partof the U.S. dye industry and the advances indisperse dye chemistry in particular.

References1. Journal of the Society of Dyers and

Colourists, Vol. 69,1953, ppl21 and 205,

2. Charlton, A. P., Modern Colorant Synthe-sis and Structure, Advances in Color Chem-istry Series, edited by A. T. Peters and H. S.Freeman, Vol. 3, Blakie Academic and Pro-fessional, 1995, pp123-153.

3. U.S. Patent No. 3,299,103.

4. German Patent No. 1,644,595.

5. U.S. Patent No. 2,990,413.

6. French Patent No. 618,307; U.S. Patent No.1,652,584.

7. U.S. Patent No. 2,753.356.

8. Annen, A., et al.. Review of Progress inColoration, Vol. 17, 1987, pp72-86.

9. Weaver, M. A., and L. Shuttleworth, Dyesand Pigments, Vol. 3, 1982, pp81-121.

10. Towns, A., Dyes and Pigments, Vol. 42,1999, pp3-28.

11. Schwander, H., Dyes and Pigments, Vol. 3,1982, pl33.

12. Straley, J. M., The Chemistry of SyntheticDyes, edited by K. Venkataraman, Aca-demic Press Inc., New York, Vol. 3, 1970,pp385-462.

13. Straley, J. M., and D. Carmiehael, CanadianTextile Journal, Vol. 76, May 1959, p48.

14. Dawson, J. F., Journal of the Society ofDyers and Colourists, Vol. 99,1983, pi 83.

15. Dawson, J. F, Review of Progress in Colora-tion, yo\. 14, 1984, p90.

16. Hallas, G., Developments in the Chemistryand Technology of Organic Dyes, edited byJ, Griffiths, Blackwell Scientific, Oxford,1984, pp31-48.

17. Shuttleworth, L. and M. A. Weaver, TheDevelopment and Application of Dyes,edited by D. Waring and G. Hallas, Ple-num Press, New York and London, 1990,PP107-163.

18. Mueller, C, American Dyestuff Reporter,Vol. 59, No. 3, March 1970, pp37-44.

19. Hallass, G., Journal of the Society of Dy-ers and Colourists, Vol. 95, 1979, pp285-294.

20. Dickey, J., et al., American Dyestuff Re-porter, Vol. 54, No. 16, 1965, pp44-47.

21. Griffiths, J., Colour and Constitution of Or-ganic Molecules, Academic Press, London,New York, 1976, pp 173-204.

22. U.S. Patent No. 3,178,405.

23. British Patent No. 1,275,603.

24. as. Patent No. 3,359,256.

25. U.S. Patent No. 3,407,189.

26. U.S. Patent No. 3,552,905.

27. U.S. Patent No. 3,525,735.

28. British Patent No. 1,080,480.

29. U.S. Patent No. 4,105, 655.

30. British Patent No. 2,017,137.

31. U.S. Patent No. 3,635,941.

32. U.S. Patent No. 3,962,209.

33. U.S. Patent No. 3,954,395.34. U.S. Patent Nos. 2,659,719; and

2,683,708-9.

35. U.S. Patent No. 3,657,215.36. U.S. Patent No. 3,639,384.

37. British Patent No. 1,394,368.

38. Mock, G, A47CC/?eweiv, Vol. 1, No. 12,December 2001, ppl8-22.

39. Mock, G., Review of Progress in Colora-tion, October 2002, pp80-87.

Author's AddressMax A. Weaver, 125 Hill Rd., Kingsport, Tenn.37664-4314; telephone 423-323-7187; e-mail maweaver@chartertn.net.

The water resistance of fabrics to wetting by water is measuredby using the AATCC Spray Test Apparatus according to AATCCTest Method 22, Water Repellency: Spray Test. The tester in-cludes the test stand, spray test nozzle assembly, hoop, and testchart. Order No. 8385.

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