(Received December 24, 1983) DYEING BEHAVIOR OF POLYESTER FIBER TREATED WITH SOLVENTS: RELATIONSHIP BETWEEN DYEABILITY AND STRUCTURE OF DISPERSE DYES

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1 T-216 SEN-I GAKKAISHI ( ñ ) (88) Note (Received December 24, 1983) DYEING BEHAVIOR OF POLYESTER FIBER TREATED WITH SOLVENTS: RELATIONSHIP BETWEEN DYEABILITY AND STRUCTURE OF DISPERSE DYES By Yong-Jin Lim*2, Mitsuru Tahara*3, Toru Takagishi, Nobuhiko Kuroki and Tomiji Wakida*1 (Department of Applied Chemistry, College of Engineering, University of Osaka Prefecture, Sakai, Osaka 591, Japan) *1(Faculty of Industrial Arts, Kyoto University of Industrial Arts and Textile Fibers, Sakyo-ku, Kyoto 606, Japan) Synopsis Polyester fiber was treated with the strongly-interacting solvents such as dimethylformamide, benzyl alcohol, and butanol. The pretreated fibers were dyed with seven kinds of disperse dyes (C. I. Disperse Yellow 7, Orange 1, Orange 3, Red 17, Violet 1, Blue 3, and Blue 7) in water and the saturation dye-uptake values were determined. The solvent-induced structural changes led to changes in dyeability. At the same time, the dyeing behaviors were found to be greatly different with the dyes investigated. The relationship between dyeability and structure of the dyes has been briefly discussed. 1. INTRODUCTION The interaction between organic solvents and synthetic fibers such as nylon, acrylic, and polyester fibers has been extensively studied in relation to the solvent dyeing.1) It is known that solvent treatments of the fibers as well as thermal ones lead to structural modifications of the fibers. The changes in fiber structure and morphology are investigated by a number of techniques. It is of interest to determine the effects of such solventinduced modifications on the dyeability of the fibers. In previous articles2-7) nylon and polyester fibers were pretreated with butanol, benzyl alcohol, dimethylformamide, tetrachloroethylene, and tetrachloroethane, which are known to be strongly- *2 Present address: Department of Industrial Chemistry, College of Engineering, Kyungpook National University, Daegu, Korea *3 Present address: Textile Research Institute of Osaka Prefecture, Izumiotsu, Osaka 595, Japan interacting solvent for the fibers, or their aqueous solutions of various compositions and the dyeing of the pretreated samples with C. I. Disperse Violet 1 (1,4-diaminoanthraquinone) in water was studied to compare with their structural changes produced by the solvent treatments. The results indicated that the dyeability is improved by the solvent treatments, and the diffusivity and the saturation uptake of the dye increase in spite of the increase in the crystallinity of the polymer. These obser vations were discussed in terms of the plasticization of the fiber structure formed during the treatment. According to Weigmann and his coworkers, 8-11) this greater accessibility was attributed to solvent induced crystallization and simultaneous void formation. In our previous investigations 3-7) only one kind of disperse dye, C. I. Disperse Violet 1, was em ployed as a typical dyestuff. In this article studies have been made of saturation limits of seven kinds of disperse dyes of different chemical structures, azo and anthraquinone dyes, on polyester fibers

2 (89) Vol.40, No.6 (1984) T-217 treated with organic solvents. It was found that the effects of solvent treatments on the dyeing behavior differ considerably with the dyes studied. 2. EXPERIMENTAL 2.1 Materials Poly(ethylene terephthalate) (PET) fiber (75 d/ 24 filaments) was used. The PET fibers were scoured in a nonionic surfactant solution (Scourol 900, Kao-Atlas Co.) at 60 Ž for 30 min and then rinsed with distilled water repeatedly. The organic solvents used for pretreatment were n-butanol, benzyl alcohol, and N, N-dimethylformamide, which were analytical reagent grade materials and used without further purification. The disperse dyes employed in this investigation are listed in Table 1. C. I. Disperse Yellow 7, Orange 1, Orange 3, and Red 17 belong to the azo-type disperse dyes dimethylformamide, aqueous butanol solution (90%), and aqueous benzyl alcohol solution (90%) at 140 Ž for 120 min under unrestrained condi tions. The liquor ratio was 1:100. The samples were then rinsed with water or with cold acetone for benzyl alcohol treatment to remove residual solvent and allowed to dry under vacuum at room temperature. 2.3 Dyeing Procedures Dyeings were carried out at 120 Ž for 5 hr in a water dyebath with a liquor ratio of 300 to 1 using a Tumblet high pressure dyeing apparatus. After dyeing the reduction cleaning for the dyed sample was done.6) Then after drying the samples (ca g) were extracted with 20 ml of mono chlorobenzene at 100 Ž with occasional shaking until the fibers became colorless. The concentra tion of dye in the extract was determined by spectrophotometric method. and Violet 1, Blue 3, and Blue 7 the anthraquinonetype ones. These dyes were first recrystallized from suitable solvents and then purified by column chromatography through silicagel. 2.2 Solvent Pretreatments The PET fibers were pretreated with water, 3. RESULTS AND DISCUSSION The saturation dye-uptake values of the seven kinds of disperse dyes for the PET fibers treated with water, dimethylformamide, aqueous 90% Table 1. Disperse dyes used.

3 T-218 (90) Table 2. Saturation dye-uptake value of polyester fiber treated with various solvents. butanol solution, and aqueous 90% benzyl alcohol solution are summarized in Table 2, in which the values of S/So, S and So being the saturation value of solvent-treated PET sample and that of untreated control sample, respectively, are also presented. In the previous articles6,7) the changes in struc ture of PET fiber that received solvent treat ments have been discussed. The dyeing behaviors of the pretreated fibers with C. I. Disperse Violet 1 were studied with reference to changes in the fine structure of the fibers. Also the dynamic visco elastic properties such as loss tangent tan ƒâ, dynamic modulus E', and dynamic loss modulus E" of the solvent-treated PET were measured and the effects of solvent treatments on the tempera ture of the main a-dispersion peak were com pared.12) In addition, density and X-ray diffraction of the samples were investigated as a measure of crystalline region.6) The morphological events taking place in the solvent-treated fibers were very large. The results6) obtained in the dyeing with Violet 1 indicated that the saturation dye uptake increases in the order, fiber pretreated with water < untreated fiber fiber pretreated with aqueous 5% butanol solution < fiber pretreated with butanol < fiber pretreated with aqueous 90% butanol solu tion for a butanol series; fiber pretreated with water < untreated fiber < fiber pretreated with aqueous 5% benzyl alcohol solution < fiber pre treated with benzyl alcohol < fiber pretreated with aqueous 90% benzyl alcohol solution for a benzyl alcohol series; fiber pretreated with water fiber pretreated with aqueous 5% dimethylformamide solution < untreated fiber < fiber pretreated with aqueous 90% dimethylformamide solution < fiber pretreated with dimethylformamide for a di methylformamide series, The dimethylformamide and benzyl alcohol (aqueous 90% solution) treat ments were most prominent. A comparison with the saturation dye-uptake values of the fibers treated with water, butanol, benzyl alcohol, and dimethylformamide clearly reflects the differences in structural modifications caused by these solvents. The dye uptake crystalline growth. that the recrystallization treatment increased with an increase in the This might be due to the fact process during the pre with the solvents or the mixtures leads to an increase in amorphous volume and then a large increase in dye uptake.8-11) Also the rate of dye uptake was increased and the dyeing transition temperature13) was lowered by the solvent treatments.6) As is apparent in Table 2, the similar results as C. I. Disperse Violet 1 are observed for the other disperse dyes, Orange 3, Red 17, Blue 3, and Blue 7: the treatments with dimethylformamide and aqueous 90% benzyl alcohol solution affect markedly on the enhancement of dye uptake. Moreover, it is interesting to find that the S/S0 values are significantly different with the dyes investigated. The S/S0 values are greatly influ enced by the structure of the dyes when the values are compared for the same solvent-treated sample. if a series of the anthraquinone dyes is compared, the relative dye uptake S/S0 increases

4 (91) Vol.40, No.6 (1984) T-219 with an increase in molecular weight of the dyes for the solvent-treated fibers: Violet 1 < Blue 3 < Blue 7. This result suggests that a larger or more bulky dye is more accessible to the solvent-treated fiber. Weigmann et al.8-11) reported that dimethyl formamide-induced structural modifications in polyester yarns lead to the formation of pores, microvoids or voids, which are corroborated by diffuse scattering in small-angle X-ray diffraction patterns, in the polyester structure and essentially yield a more open structure. Saturation dyeuptake values and void formation were directly related. The increased amount of dyes is believed to be held in voids in the fiber structure formed during solvent treatment. From their results it might be reasonable to consider that the open, porous structure is accessible to penetration of the larger molecular-sized dye and effectively entraps the dye molecule in the fiber structure, leading to the higher level of dye uptake and hence S/So value. The larger dye molecule enters a gap between polymer segments which is large enough to accommodate the molecule and can tightly fit to the highly disordered amorphous regions. This should lead to effective entrapment of the dye molecule in the fiber structure. In marked contrast to the organic solvent treatments, water treatment causes a decrease in S/So value with increasing molecular weight of the anthraquinone dyes. This might be due to the growth of crystalline region by water treatment and small plastisizing effect. Thus the larger dye molecule would be difficult to penetrate the amorphous region of the fiber treated with water. The situation similar to that described above for the anthraquinone dyes is observed for an azo-dye series, C. I. Disperse Orange 3 and Red 17 with the exception of Orange 1 and Yellow 7: the S/S0 value of Red 17 is larger than that of Orange 3 for any solvent-treated fiber. It is apparent that with Orange 1 and Yellow 7, in particular the latter dye, dime thylformamide and benzyl alcohol treat ments have essentially no effect on the extent of dye uptake and hence S/S0 value. The treatments result in approximately the similar dye uptake compared with that of the untreated control sample. Furthermore, butanol treatment induces a substantial decrease in dye uptake. A likely interpretation is that the differences in dyeability between these two dyes and the other dyes used in this study must be associated with structural features in the dyes. With the dyeing behavior of Orange 1 and Yellow 7 the question remains un answered at this point. However hints are given to solve this problem: Orange 1 and Yellow 7 consist of a rod-like and ligid structure and an abnormally high dye uptake is observed for these two dyes. Masuko et al.14) assumed that disperse dyes are dissolved into two kinds of amorphous regions, i.e., the end and side regions, within crystalline polymers and rod-like dye molecules, for example Yellow 7, are dyed preferentially in the side regions rather than the end ones. As is apparent in Table 2, an extremely high dye uptake of Yellow 7 may be an indication of binding of the dye to the side amorphous regions. The solvent treatments cause a growth of crystalline regions as described above. According to the mosaic-block structure model which Masuko et al. used to establish their sorption model, this situation par ticipates in an increase of the uptake of dye, in particular Yellow 7, in the side region. In contrast the amount of dye uptake in the end region may decrease. Subsequently, the overall amount of dye uptake for Yellow 7 may remain almost unchanged after the solvent treatments. It seems likely that the solvent treatments of the PET fiber affect the dyeability of the rod-like dyes and the bulky ones in different ways. However further study is necessary to clarify this situation. REFERENCES 1) See references cited in T. Takagishi, Sen-i Gakkaishi. 36, P-401 (1980) 2) T. Wakida, T. Suzuki, I. Aoki, T. Takagishi and N. Kuroki, Sen-i Gakkaishi, 31, T-428 (1975) 3) T. Wakida, T. Takagishi, A. Katayama and N. Kuroki, Sen-i Gakkaishi, 31, T-433 (1975) 4) T. Wakida, T. Takagishi, A. Katayama and N. Kuroki, Sen-i Gakkaishi, 32, T-172 (1976) 5) T. Takagishi, T. Wakida and N. Kuroki, Sen-i Gakkaishi, 34, T-30 (1978) 6) T. Takagishi, T. Wakida and N. Kuroki, Sen-i Gakkaishi, 34, T-536 (1978) 7) T. Wakida, T. Takagishi, G. J. Kim and N. Kuroki, Sen-i Gakkaishi, 39, T-87 (1983) 8) H.-D. Weigmann, M. G. Scott, A. S. Ribnick and L. Rebenfeld, Textile Res. J., 46, 574 (1976)

5 T-220 SEN-I GAKKAISHI ( ñ ) (92) 9) H.-D. Weigmann, M. G. Scott, A. S. Ribnick and R. D. Matkowsky, Textile Res. J., 47, 745 (1977) 10) H.-D. Weigmann, M.G. Scott and A.S. Ribnick, Textile Res. J., 47, 761 (1977) 11) H.-D. Weigmann, M.G. Scott and A.S. Ribnick, Textile Res. J., 48, 4 (1978) 12) T. Wakida, Sen-i Gakkaishi, 37, T-181 (1981) 13) Z. Gur-Arieh and W. C. Ingamells, J. Soc. Dyers Colour., 90, 8 (1974) 14) T. Masuko, S. Hasegawa, K. Yonetake and M. Karasawa, Makromol. Chem., 182, 2049 (1981)

DYEING RATE OF STRETCHED WOOL FIBER IV - THE EFFECT OF THE MODIFICATION OF CELL MEMBRANE COMPLEX-

(93)Vol.44, No. 11 (1988)569 Transaction (Received April 11, 1988) DYEING RATE OF STRETCHED WOOL FIBER IV - THE EFFECT OF THE MODIFICATION OF CELL MEMBRANE COMPLEX- By Kyohei Joko '1 and Joichi Koga *2