Recent Advances in Disperse Dye Development and Applications

By ALAN T. LEAVER, BRIAN GLOVER and PETER W. LEADBETTER, IC1 Colours. Manchester IJnited Kingdom olyester fiber production in the U.S. obvious needs. Firstly, there is a need for Poor wetfastness P fell markedly in 1990. Stapleproduc- new dyes to be tailored to satisfy shorter, 0 Expensive tion fell by 12.3% and filament production reproducible and more economical dyeing Environmental problems in manu- by 8.7% compared with 1989 (I). In 1991 processes. Secondly, with the increasing facture some recovery is expected as the country use of polyester and its blends in lei- Compared with many other dye types, comes out of recession with increases in surewear and sportswear, there is a clear anthraquinone disperse dyes are tinctori- consumer spending and housing pur- demand for dyes of higher wetfastness. ally weak. Furthermore, with the intro- chases. On a world basis, the forecasts are This requirement has been exacerbated by duction of detergents and multifiber strips much more optimistic. Latest estimates the introduction of fabrics based on poly- to evaluate wetfastness, they have been put the long term growth rates for polyes- ester microfibers where higher depths of found to have, in the main, poor wetfast- ter fiber at 5% per annum against 3% for all shade have to be dyed to obtain the same ness, being particularly poor with respect Ebers. The highest growth rates are pre- visual yield as conventional polyester. to staining adjacent nylon. For dye users dicted in Asia and the Far East where over Last, but by no means least, new disperse they are expensive relative to mono-azo 8% per annum is forecast for the period dye development has to be directed to- disperse dyes; for dye manufacturers they 1990-2000. Over the same period a growth wards minimizing pollution of the envi- are environmentally problematical. rate ofjust 0.5% per annum is predicted in ronment. Many key anthraquinone disperse dyes the U.S. These objectives are not mutally exclu- are derived from sulphonation of an- It is against this background ofa signifi- sive but interrelated, and all need to be thraquinone itself, which for most manu- cant global growth rate in polyester fiber taken into account in any dyedevelopment facturers requires the use of mercury that major dye manufacturers continue to program. catalysts. Hence, there has been a clear devote substantial resources to the devel- need to find replacements for anthraqui- for the Properties of Anthraquinone none dyes to counter these deficiencies. opment of new disperse dyes Disperse Dyes coloration of polyester and its blends, This does not mean that anthraquinone particularly with cellulose. Anthraquinone disperse dyes were devel- disperse dyes do not still have their place. Disperse dye development has to be oped more than 60 years ago for the They do. They are still seen as essential to directed towards satisfying a number of coloration of cellulose acetate. They were satisfy the lightfastness requirements for 2, subsequently found suitable for the color- automotive outlets. They are still used ation of other such synthetic fibers as extensively for such nonpolyester syn- nylon, cellulose triacetate and polyester. thetic fibers as acetate, triacetate and The commercial development of new It was the phenomenal growthof polyes- nylon, together with blends of these sub- disperse dyes for 100% polyester and ter fiber production during the 1950s and strates with polyester. Probablytheirmain polyester/cellulose blends is reviewed. 1960s that signaled an extensive research The deficiencies of traditional use today is in pale shade trichromatic anthraquinone disperse dyes for bright and development program for new dis- dyeing where their good coverage, good red and bright blue shades are perse dyes for polyester. Research was reproducibility and good leveling proper- highlighted from the standpoint of largely concentrated on substituted an- ties are still needed, and their obvious today's requirements for higher thraquinone and substituted benzenoid deficiencies of expense and poor wetfast- wetfastness and more economical mono-azo structures. ness can be largely discounted. processing. More acceptable alternative The anthraquinone disperse dyes devel- Some developments have continued. dyes are described with emphasis on oped over this period had some clear Japanese manufacturers have devised and exhaust dyeing of 100% polyester successfully operated mercury-free pro- microfibers and one-bath dyeing of benefits. polyester/cellulose blends. Some Brightness of shade (particularly cesses for anthraquinone intermediates. aspects aimed at reducing blues and reds) Ciba-Geigy has recently added a com- environmental pollution, namely Very good lightfastness pletely new anthraquinone disperse dye to alkali-clearable disperse dyes and choice Good level dyeing properties its range: Terasil Brilliant Blue FFL (C.I. of formulating agents, are discussed. 0 Good coverage properties Disperse Blue 361), a bright mid-blue of Good reproducibility high lightfastness. A further attraction of anthraquinone However, with few exceptions, recent KEY TERMS dyes was the fact that many gave good developments in disperse dyes have con- yields with carriers and enabled satisfac- centrated on other types of dye structures. tory dyeings to be achieved at the boil, in Many projects have been aimed at improv- Anthraquinone Dyes nonpressurized machinery at a time when ing on and replacing anthraquinone dis- Benzodifuranone Dyes atmospheric dyeing machines were more perse dyes and satisfying demands for the Disperse Dyes common. highest quality performance. Polyester/Cellulose During the past 20 years, however, the Polyester Fibers following deficiencies of anthraquinone Replacements for Anthraquinone Polyester Microfibers disperse dyes have come forward. Disperse Dyes Tinctorially weak 0 Bright Blues. In thelate 1960sand early

18 Cco Vol. 24, No. 1 1970s bright blue mono-azo disperse dyes conjugated double bonds it possesses.4-n. started to appear and be offered as poten- Table 1. Comparison of Nylon obvious approach was to try to synthesize Staining: C.I. Disperse Blue, 165 vs. new molecules similar in structure to tial replacements for anthraquinone dis- C.I. Disperse Blue 56 perse dyes. Typical of these dyes was I 1 anthraquinone dyes but containing an C.I. Disperse Blue 165 (Fig. 1). This increased number of conjugated double dye possesses a significant improvement Disperse Dye IS0 105 bonds. in tinctorial strength, being more than Preparations’ C06.CE Wash Test A search of the literature revealed that three times stronger than the popular Pb NC Junek (2) in 1960 had reported the forma- anthraquinone C.I. Disperse Blue 56 C.I. Disperse Blue 56 4 2-3 tion of a novel red lin-pentacenequinone ‘2.1. Disperse Blue 165 4 4 (Fig. 2). - from the reduction of benzoquinone with As shown in Table 1, the wetfastness of aDyes were applied at 1/1 standard depth cyanoacetic acid. Greenhalgh (3),at ICI, the dye was also superior when subjected and heatset for 30 seconds at 180C. bP = stain repeated this work but could not confirm to the IS0 105 C06/C2 washfastness test, on polyester. CN = stain on nylon. the reported structure. After extensive with much lower staining of nylon adja- analysis and spectroscopic studies, the cent fabric. superior to other azo blues in its resistance dihydroxybenzodifuranone structure was However, while the deficiencies of low todecomposition during high temperature proposed and confirmed as correct. This tinctorial strength, low wetfastness and dyeing. Its reproducibility is of the same particular dye was very dull bluish red and cost ineffectiveness had been largely over- order as C.1. Disperse Blue 56 and with its of no commerical value. But as a new come, the new mono-azo dye was more superior heatfastness and wetfastness, and chromogenic system, it was of great signif- easily reduced during a high temperature good cotton reserve, it is ideally suited for icance. dyeing cycle and as a consequence was less batchwise dyeing, continuous dyeing and reproducible, particularly in tertiary Commerical Development printing of 100% polyester and polyester/ Of Benzodifuranone Dyes shades. The dye found great acceptance in cotton blends. It is being marketed as continuous dyeing outlets on polyester/ Dispersol Blue C-RN 200 Grains. IC1 has since developed two very bright cellulose blends owing to its higher heat 0 Bright Reds. A very similar line of red dyes based on benzodifuranone chem- and wetfastness, but in batchwisedyeing it development has been followed in the istry-Dispersol Red C-BN and Dispersol has been only moderately successful. replacement of the popular bright bluish- Brilliant Scarlet D-SF. Both are being The shade of C.I. Disperse Blue 165 is red anthraquinone dye, C.I. Disperse Red marketed in solid and liquid forms for also considerably greener than C.I. Dis- 60 (Fig. 4). Like the anthraquinone blue, it exhaust and continuous dyeing outlets. perse Blue 56. On shade grounds alone, it is still widely used in pale tertiary shades The same two dyes have also been specially could not convincingly be offered as a owing to its excellent reproducibility. But formulated for use in discharge printing of viable alternative. This last objection has for medium to heavy shades it has been 100% polyester and polyester/cellulose been largely overcome in the last two to largely replaced by the introduction in the blends as Dispersol Red BN PC Liquid three years by the development of a new late 1970s of the mono-azo Bayer dye, and Dispersol Brilliant Scarlet SF PC dye with a closely related structure, C.I. Resolin Red F3BS (C.I. Disperse Red Liquid, making a total of six sales products Disperse Blue 366 (Fig. 3). 343). This dye has superior heatfastness in all. It is also planned to extend the range This dye is very much redder than C.I. and wetfastness compared with an- of benzodifuranone dyes to other shade Disperse Blue 56 but mixtures containing thraquinonedye, and tinctorially it is more areas. thisdyeare now being marketed which are than three times stronger. Hence, it is a far 0 Properties of Benzodifuranone Dyes i: similar in hue to the anthraquinone dye. more economical reddening component in Relation to Industry Trends. The two Typical mixtures are C.I. Disperse Blue although it is significantly duller. benzodifuranone dyes developed to date 165/366 or C.I. Disperse Blue 367/366. ICI’s approach to replacing the tinctori- can be applied by conventional application Both are close in shade to C.I. Disperse ally weak anthraquinone reds, C.I. Dis- techniques. However, for exhaust dyeing Blue 56 but slightly duller. As might be perse Red 60 and 9 I, led to the develop- of 100% polyester or polyester/cellulose expected, they show much inferior resis- ment of a completely new class of disperse blends, it is preferable to use top tempera- tance to reduction in the dyebath. dyes, the benzodifuranones. In the 1970s tures of 135-14OC rather than 130C to Very recently, IC1 has developed a new IC1 researchers were pondering how they ensure consistency of color yield and rapid mono-azo thiophene bright blue, slightly could increase the tinctorial strength of diffusion of the dyes into polyester. This redder in shade than C.I. Disperse Blue 56 anthraquinone dyes and still retain their slight deviation from established practice but marginally brighter. This dye finally brightness of shade. is more than outzeighed by the unique explodes the myth that mono-azo blue One factor which affects the tinctorial wetfastness characteristics possessed by dyes cannot achieve the brightness of C.I. strength of a molecule is the number of the dyes. Disperse Blue 56. Furthermore, it is far Throughout the 1980s there was a

,C N PjHCOCH3 CN CH3

‘CN OH 0 NH2 ‘C N

Fig. 1. (2.1. Disperse Blue I65 Fig. 2. C.I. Disperse Blue 56. Fig. 3. C.I. Disperse Blue 366.

0 0 0

0 OH

Fig. 4. C.I. Disperse Red 60. Fig. 5. Questionable formation of pentacenequinone

January 1992 co3 19 I Table II. Wetfastness of Dispersol Red C-BN vs. Other Table 111. Wetfastness of Dispersol Brilliant Scarlet D-SF Disperse Dyes on Polyester Microfiber vs. Other Disperse Dyes on Polyester Microfiber I I

Marks and Spencer Marks and Spencer C-4A Wash Test (6OC) C-4A Wash Test (6OC) Disperse Dye - Disperse Dye __ Preparations Pa Cb NC Preparations P' Cb NC Dispersol Red C-BN Grains 5 5 5 Dispersol Brilliant Scarlet C I Disperse Red 127 4-5 4-5 3-4 D SF 200 Grains 5 5 5 C I Disperse Red 146 4-5 4-5 3-4 C I Disperse Red 352 4-5 5 3 C I Disperse Red 92 4-5 4-5 2-3 C I Disperse Red 135 4-5 4-5 3-4 C I Disperse Red 343 4-5 4-5 3-4 C I Disperse Red 200 4-5 4-5 3 C I Disperse Red 190 4-5 4-5 3 C I Disperse Red 151 4-5 4-5 3-4 C I Disperse Red 206 5 4 3-4 C I Disperse Red 153 4-5 4-5 3 C I Disperse Red 359 4 4-5 3 ~~ - "P = Stain on polyester hC = Stain on cotton CN = Stain on nylon aP = Stain on polyester. bC = Stain on cotton. CN = Staln on nylon.

Disperse Dyes Designed worldwide growth in blends of polyester nological Achievement which acknowl- To Reduce Pollution and cellulosic fibers, particularly for edged the outstanding contribution these All new dyes which are to be imported by sportswear and leisurewear. There was dyes are making to the coloration of or manufactured in the U.S., Western also greater popularity for contrast color polyester and its blends. Europe, Japan, Canada, Australia or New panels in the same garment or white effect 0 Benzodifuranone Dyes Applied to Zealand have to satisfy stringent regula- trim adjacent to deep shades. Further- Polyester Microfibers. Conventional fila- tions pertaining to their possible toxicity, more, more stringent washfastness tests ment polyesters are normally considered including their toxicity to fish. Any dye became the norm-e.g., Adidas Wash to be within the range 2-6 dtexpf, weight- failing these requirements is not allowed to Test, Marks and Spencer C-4A Wash Test reduced polyesters between 1.2- 1.6 dtexpf be freely imported or sold. (60C). National and international bodies and polyester microfibers on the order of Until recently, with few exceptions, introduced similar tests which became 0.3 and 0.99 dtexpf. there was less attention paid to the possible widely adopted, such as AATCC Test As early as 1944, Fothergill(4) pointed pollution caused by coloration processes Method61-IIAandIIIAandtheISO 105 out that the dye concentration required to and how the structure or formulation of a C06.C2 detergent wash tests. achieve a given depth of shade was in- dye might reduce this. Conventional disperse dyes have great versely proportional to the square root of difficulty satisfying these tests, particu- the fiber denier as follows: Discharge Printing larly when the dyed fiber has been sub- dtexpfz One notable exception was the develop- jected to a heat setting and/or finishing ment of Dispersol PC dyes in the late treatment. During heat setting, thermo- 1970s which was designed for the dis- migration occurs and the dye moves out of where: charge printing of 100% polyester. Up to the polyester and accumulates on the fiber CI = % dye applied to fiber 1 about 1976, the technique used was to pad surface. Subsequent washing of the dyed C2 = %dye applied to fiber 2 .. the ground shade with an azo disperse dye fiber in the presence of a multifiber strip dtexpfl = decitex per filament of fiber 1 followed by drying. The azo dye was causes staining of one or more of the dtexpfr = decitex per filament of fiber 2 chosen so that it could be easilydestroyed adjacent fibers. Adjacent nylon is usually Subsequent studies have largely con- by reduction. the most affected by disperse dyes. Obvi- firmed this relationship, but it is known to The discharging (reducing) agent to- ously the heavier the depth of shade the be affected by a number of factors, partic- gether with any illuminating dye was worse the resultant staining. ularly the shape of the fiber cross section printed and the fabricdried again. Finally, By far the best performance in the tests (5). during the fixation process-steaming or is achieved by the new benzodifuranone Hence, to achieve the same visual depth dry heat-those parts of the ground shade dyes. They are clearly superior to all other of shade on a polyester microfiber as on in contact with the discharge agent were red disperse dyes. Experience has shown it conventional polyester it is necessary to destroyed and the illuminating dye, if is often possible simply to rinse the dyed apply considerably more dye. Application present, was fixed in its place. Obviously fabric or yarn after dyeing and still satisfy of much heavier depths of shadeon polyes- the illuminating dyes were chosen SO that these stringent tests, thereby saving a ter microfiber leads to a significant deteri- they were stable to reduction by the clearing treatment. The uniqueness of oration in the wetfastness of microfibers discharge agent. Usually these were an- these dyes was recognized in the UK in compared with conventional polyester. thraquinone based. 1990 with The Queen's Award for Tech- Work at IC1 with benzodifuranonedyes The common reducing agents employed and microfibers has shown that the bene- in this process were all heavy metal salts, fits of these dyes are even more exagger- namely, stannous chloride, zinc formalde- ated on microfibers. They continue to hyde sulfoxylate, cuprous acetate or simi- exhibit acceptable levels of wetfastness lar salts. Even at the time, effluent contain- while most other disperse dyes deteriorate ing heavy metals from the washing off markedly(Tab1es 11,111).

Insoluble Soluble

Allinily for Polyester No affinity for Polyester

Fig. 6. The first benzodifuranone dye. Fig. 7. General structure ofDisperso1 PC d\es.

20 a53 Vol. 24, No. 1 process was widely regarded as unaccept- .. able. This concern was one of the factors which led to the development of Dispersol PC disperse dyes which allowed the ground shade to be discharged by simple alkali. These novel dyes were character- ized by the presence of diester groups (Fig. 7). In its diester form a Dispersol PC dye acts like a conventional disperse dye. It is insoluble, with an affinity for polyester. By treatment with dilute alkali, it can be I Load Glaubofs OISPERSOL C dyes converted into a water soluble species with Alkall Wash off no affinityat all for polyester. + 1111 sail. acelic + PROCION H-E dyes Thus if a Dispersol PC dye is used for the acid, auxiliaries ground shade and an illuminating dye is Fig. 8. The Select I1 process. chosen which is stable to alkali, then the ground shade can be discharged by simply using alkali. No heavy metal salts are ter and cotton and effects fixation of the Borregaard Industries, a major supplier of needed. reactive dye. formulating agents, has has its major products independently assessed for toxic- Exhaust Dyeing Formulation Aspects ity to fish, toxicity to micro-organisms and Dispersol PC dyes are alkali-clearable Throughout this paper there have been biodegradability by the Batelle-Institute, dyes, as they are solubilized by alkali. This many references to Colour Index names. Frankfurt. This type of data is becoming property can be used to advantage in There is often a mistaken belief that dyes increasing important to the dye manufac- exhaust dyeing of both 100%polyester and possessing the same C.I. name are identi- turer who wishes to minimize adverse polyester/cellulose blends. cal in every respect. This is not the case. effects on the environment. Most disperse dyes have a high exhaus- The C.I. name only refers to the colored tion on polyester, often achieving 95% or species in a dye and in the case of disperse Conclusion higher. However, to achieve the best levels dyes may represent as little as 10% of the The growth of polyester fiber in the textile of wetfastness, it is necessary to remove actual dye as sold. The rest of the dye is industry, the development of new fibers the residual dye from the polyester surface loosely classified as formulating agents. and fabrics, the need for economical and after dyeing to prevent it from staining Formulating agents are necessary to shorter processing methods and ever other fibers. This is normally achieved by a convert what is an insoluble dye into a changing fastness requirements all signify reduction clearing treatment using caustic preparation that can be evenly applied to an increasing market for new disperse soda and hydros (sodium dithionite), polyester and its blends from an aqueous dyes. which reduces the surface dye. Hydros, as medium. Thus, for high temperature dye- The new thiophene based azo bright a strong reducing agent, places a very high ing, the formulatingagents must beable to reddish blue Dispersol Blue C-RN should Biochemical Oxygen Demand on any ef- provide the overall preparation with good, find widespread acceptance due to its fluent system. On the other hand, alkali- high temperaturedispersion stability. benefits over existing products. The new clearable dyes completely obviate the need The choice of formulating agents is benzodifuranone dyes-Dispersol Red for hydros and should significantly reduce crucial to good and reproducible dyeing C-BN and Dispersol Brilliant Scarlet the cost of effluent treatment. performance. An injudicious choice can D-SF-have outstanding levels of wet- IC1 has a wide range of alkali-clearable lead to dye restraining, fiber staining, fastness, ideally suited for polyester mi- disperse dyes, some based on the diester lower fastness, excessive foaming and crofibers. Alkali-clearable disperse dyes chemistry of the Dispersol PC dyes, some adverse interaction with other chemicals simplify polyester and polyester/cellulose on novel thiophene chemistry, as exempli- commonly used in the dyebath. Indeed, dyeing and printing as well as making a fied by Dispersol Navy C-MSA Liquid, where a dye is sensitive to the reduction or significant contribution to reducing pollu- and some based on our new benzodifura- hydrolysis, the formulating agent can tion from dyehouse effluent, as can the none dyes. greatly influence to what extent this oc- choiceof their formulating agents. CCo curs. Hence, there are many reasons why Select II Process disperse dyes, classified by the same C.I. References The advent of alkali-clearable disperse name can perform markedly different in (I) Phipps, J., EIU Textile Outlook Interna- dyes has enabled highly productive one- the dyebath, or for that matter in continu- rional, May 1991, p9. bath, two-stage processes to be developed ous dyeing or printing. (2) Junek, H.,Mona/she/feChemie.Vol. 91,1960, p479; ihid., Vol. 92, 1961, p633; ihid., Vol. 93, 1961, for such exhaust dyeing of polyester/ One aspect which has received little p44. cellulosic blends as the Select I1 Process attention is the contribution formulating (3) Greenhalgh, C. W., Dyes & Pigments, Vol. I, (Fig. 8). agents make to the effluent. In a typical 1980, pl03. This method has been widely promoted exhaust dyeing, virtually all the dye is (4) Fothergill, F.. Journal of theSociety of Dyers andColourists, Vol. 60, 1944, p93. throughout the world by IC1 (6). Com- taken up by the polyester substrate and its (5) Steinlin, F.. Melliand Texrilberichte. Vol. 3, pared with theconventional two-bath dye- presence in the resulting effluent is mini- 1983. p212. ing method, improved productivity of 30% mal. The formulating agents, however, (6) Menzies, 1. D. and P. W. Leadhetter, Book o/ being water soluble are not adsorbed by Papers, 198s AATCC International Conference & can be achieved. Both the disperse dye for Exhibition, Montreal, p108. the polyester component and the reactive the substrate to any significant extent and dye (Procion H-E dye) are introduced at virtually all become part of the effluent. Author’s Address the start of the dyeing cycle. The polyester Reputable manufacturers of formulat- Alan T. Leaver, IC1 Colour & Fine component is dyed first and, on cooling ing agents have begun to provide data for Chemicals, P. 0.Box 42, Hexagon House, back, alkali is added. This clears any the formulation chemist on the properties Blackley, Manchester M9 3DA, United residual dispersedye from both the polyes- of their products in effluent. For example, Kingdom.

January 1992 033 21