Fibre acetate

The chemical structure of acetate fibres are shown in Fig. 1-19. In secondary 

Both types of acetate fibres have a polymer backbone of hexagonal units. The macro structure of acetate fibres is very similar to that of viscose and displays no discernible micro-structures. Acetate fibre complicates close packing because of bulky structure. Both the fibres are amorphous (60% or less) and are held together by Van der Waals forces. Triacetate has certain properties that are different from secondary acetate fibres (Table 1.15). Secondary acetate is about 160 nm TABLE 1.15 

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New water-insol. naphthalic acid imide dyestuffs - used to dye blends of polyamide or urethane- and polyester or tri acetate fibres having good light and washing fastness C91-110.342 RICH DE GB LI) ... 

W. Beckmann, in D. M. Nunn, ed.. The Dyeing of Synthetic Polymer and Acetate Fibres, Dyers Company PubHcations Tmst, London, 1979, Chapt. 5. 

The compound exists normally as the trans or ( )-isomer 21a. This molecule is essentially planar both in the solid state and in solution, although in the gas phase there is evidence that it deviates from planarity. When irradiated with UY light, the ( )-isomer undergoes conversion substantially into the cis or (Z)-isomer 21b which may be isolated as a pure compound. In darkness, the (Z)-isomer reverts thermally to the (F)-isomer which is thermodynamically more stable because of reduced steric congestion. Some early disperse dyes, which were relatively simple azobenzene derivatives introduced commercially initially for application to cellulose acetate fibres, were found to be prone to photochromism (formerly referred to as phototropy), a reversible light-induced colour change. C. I. Disperse Red 1 (22) is an example of a dye which has been observed, under certain circumstances, to give rise to this phenomenon. 

The dyeing of synthetic-polymer and acetate fibres, Ed. D M Nunn (Bradford SDC, 1979). 

Numerous disperse dyes are marketed in a metastable crystalline form that gives significantly higher uptake than the corresponding more stable modification. The molar free enthalpy difference can be used as a criterion of the relative thermodynamic stabilities of two different modifications [53]. Certain dyes can be isolated in several different morphological forms. For example, an azopyrazole yellow disperse dye (3.52) was prepared in five different crystal forms and applied to cellulose acetate fibres. Each form exhibited a different saturation limit, the less stable modifications giving the higher values [54]. 

Uncharged styryl (methine) disperse dyes were originally introduced to provide greenish yellow colours on cellulose acetate fibres. One such dye still in use is Cl Disperse Yellow 31 (6.226), which is made by condensing 4-(N-butyl-N-chloroethylamino)benzaldehyde with ethyl cyanoacetate. Suitable compounds for polyester usually contain the electron-accepting dicyanovinyl group, introduced with the aid of malononitrile. An increased molecular size leads to improved fastness to sublimation, as in the case of Cl Disperse Yellow 99 (6.227). A novel polymethine-type structure of great interest is present in Cl Disperse Blue 354 (6.228), which is claimed to be the most brilliant blue disperse dye currently available [85]. 

In 1894, Cross and Bevan acetylated cellulose to get cellulose acetate. In 1921, cellulose acetate fibres were marketed for the first time as Celanese. ... 

D.M. Nunn (Ed.), The Dyeing of Synthetic-polymer and Acetate Fibres, Society of Dyers and Colourists, Bradford, 1979. 

Bleaching of acetate fibres with sodium chlorite... 

It is more safe to carry out bleaching of acetate fibres with sodium chlorite than with hydrogen peroxide. Bleaching can be carried out with sodium chlorite (0.5-2 g/1) in presence of mono substituted ammonium phosphate (0.5-2 g/1) and non-ionic detergent at 70-80 C for 60-100 min. 

Peracetic acid is very suitable for bleaching of cellulose acetate fibres. The liquor should be made-up in the following manner ... 

This must place some doubt on results of fluorescent brightening agent concentrations determined in this way. A similar technique is also used to determine fluorescent brightening agents on nylon and acetate fibres [55]. A m-cresol-metha-nol mixture is used as solvent for nylon fibres and DMF for the acetate fibres. Extraction with a DMF-water mixture is recommended for cellulosic fibres. 16.13.3 Instrumental assessment... 

When examined under the microscope acetate fibres show no longitudinal striations. The cross-sections are irregular but more in the shape of lobes and the indentations are not so deep as in viscose (Fig. 6.19a and b). 

It has been known for a long time that it is possible to dye acetate fibres with azoic dyes provided the right combinations are selected and suitable modifications in the method of application are made. Wallwork (J.S.D.C., 1935, 51,415) proposed a reversal of the norrnal procedure by impregnating with the base first, diazotizing, and then coupling with the /i-hydroxynaph-thoic acid derivative or, alternatively, impregnating with a mixture of the... 

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