Cellulose triacetate dyeing

It is difficult for dye solutions in water to penetrate synthetic fibers such as polyester, cellulose triacetate, polyamides, and polyacryUcs which are somewhat hydrophobic. The rate of water imbibition differs with each fiber as shown in Table 1 as compared to viscose (see Fibers, regenerated CELLULOSics), which imbibes water at the rate of 100% (1). The low imbibition rate is attributed to the high T obtained when the polymeric fibers are drawn. During this drawing operation the polymer chains become highly oriented and tightly packed, forming a stmcture practically free of voids. 

Atmospheric ozone has also been reported as causing fading of certain dyes in some countries [425,426] diallyl phthalate (10.182) used as a carrier in the dyeing of cellulose triacetate fibres, is said to be an effective ozone inhibitor [427]. Nylon, especially when dyed with certain amino-substituted anthraquinone blue acid dyes, can also be susceptible to ozone fading [428,429]. Selection of ozone-resistant dyes is obviously the best counteractive measure, although hindered phenols (10.161) and hindered amines (10.162) are said to provide some protection. 

In order to facilitate satisfactory dye uptake, the molecular size of a disperse dye must be kept small monoazo structures are therefore exceptionally important, particularly in the coloration of polyester and cellulose triacetate. In the yellow shade area, molecular size generally poses no problem and the various available coupling components can all be used without making the molecule too large. A very simple example of the type of structure employed using a phenolic coupling component is Cl Disperse Yellow 3 (4-72). This dye is known to cause skin sensitisation when on nylon [85] and can also provoke an allergic reaction [86]. 

Above Illustrating adsorption of typical non-ionic disperse dye by cellulose triacetate. Below (Schematic) Illustrating loss of affinity of polar groups by screening effect of solvated water on ionic group, in a typical sulphate-ester dye. 

Dye carriers, occasionally called dyeing accelerants, are used on cellulose triacetate libers, but have found their greatest use in the dyeing of polyester. 

Cellulose Triacetate. Cellulose acetate having 92% or more of the hydroxyl groups acetylated is referred to as triacetate. This fiber is characteristically more resistant to alkali than the usual acetate and may be scoured, generally, in open-width, with aqueous solulions of a synthetic surfactant and soda ash. Triacetate is a hydrophobic liber, as compared to secondary acetate, and consequently does not dye rapidly. It is necessary to increase the rate of diffusion of the disperse dye into the fiber by increasing the dyeing temperature to 110— 130CC or using a dye accelerant or carrier, or both. 

Disperse dyes are currently used to dye cellulose 2.5-acetate, cellulose triacetate, synthetic polyamides, and to a lesser degree, polyacrylonitrile and polypropylene. Their major application is clearly for dyeing polyesters. 

Representatives of this class are also suitable for dyeing cellulose triacetate. However, sufficient lightfastness is not obtained on synthetic polyamides [10], Other industrially important 2,6-dicyanoazo dyes are obtained by using diethyl- m -toluidine and 3-diethylaminophenylmethansulfonamide [52603-47-1] as coupling components (see 23 and 24, respectively). 

For printing disperse dyes on cellulose acetate, dyes are selected according to their colorfastness on 2.5-acetate and triacetate. Fixation is carried out for 2.5-acetate in saturated steam at 102°C for 20-40 min for triacetate 20-30 min at 0.25 MPa (127°C) or in superheated steam 8-6 min at 165-185 °C. 

Report of Committee Dyeing Properties of Disperse Dyes, I Cellulose Acetate, J. Soc. Dyers Colour. 80 (1964) 237-242, II Cellulose Triacetate, 81 (1965) 209-210 J.-H. Choi, A.D. Towns, Color Technol. 117 (2001), 127-133. 

The color of cellulose acetate dyed with some disperse dyes is subject to gas fading. Treatment of the dyed material with diethanolamine or melamine can overcome the problem (3). Similarly, with cellulose triacetate, gas fading of dyes can occur. It has been stated that protection can be obtained by the application of an inhibitor (3). 

Cellulose acetate was first prepared in 1865, and was a suitable candidate to replace nitrocellulose. Cellulose triacetate, however, was less soluble in common solvents than nitrocellulose and also was difficult to dye. Lower levels of acetylation gave more tractable, fiber-formable products, which could be more easily dyed, and could be formed into film suitable for photographic use. These were the so-called acetate rayon fibers and plastics, which were also considerably safer to use than nitrocellulose. 

A similar series of tests for the assessment of the dyeing properties of Disperse Dyes on cellulose triacetate has been published J.S.D.C., 1965, 81, 209). 

In cellulose triacetate virtually all the hydroxyl groups in the cellulose have been acetylated and this makes the fibre more hydrophobic and, therefore, less receptive to dye molecules. Triacetate differs from secondary cellulose acetate in that it can be heat set, making it in this respect competitive with the true synthetic fibres. Steam setting is made difficult because tried extends slightly during the process, unlike the synthetic fibres which contract. This adds to the difficulty of fixing dimensions and may cause a ripple effect in the warp direction. For this reason dry-heat setting is preferred because it is not accompanied by extension. 

Photographic emulsions composed of octahedral silver bromide grains were used in these experiments. The average grain size was 0.7 pm, or 0.2 pm. Methanolic solutions of various dyes were added to the emulsions, which were then coated at about 40 mg silver bromide/dm and at about 30 mg gelatin/dm on cellulose triacetate film base. The coated films were subjected to both ESR and sensitometric measurements at room temperature. 

Camille and Henry Dreyfus developed the first commercial process to manufacture cellulose acetate in 1905 and commercialized the spinning of cellulose acetate fibers in 1924 in the United States. At that time, the only other human-made fiber was viscose rayon, which was still in its early stages of commercialization. The main textile fibers were natural fibers cotton, wool, silk, and flax. Cellulose triacetate textile fiber was commercialized later in the 1950s. The tremendous technical effort by the Dreyfus Brothers resulted in more than 300 patents describing such significant inventions as the dry-spinning process and disperse dyeing. 

Chem. Descrip. y-Butyrolactone CAS 96-48-0 EINECS/ELINCS 202-509-5 Uses Solvent for PAN, PS, fluorinated hydrocarbons, cellulose triacetate, shellac, used in paint removers, petrol, processing, hectograph process, specialty Inks Intermediate for aliphatic and cyclic compds. reaction and diluent solvent for pesticides dyeing of acetate wetting agent for cellulose acetate films, fibers solvent welding of plastic films in adhesive applies. 

Adipic acid/epoxypropyl diethylenetriamine copolymer Benzalkonium chloride p-Dimethoxybenzene Hexamethylenetetramine Lauralkonium chloride fixative, dyes on cellulosic fibers Dicyandiamide formaldehyde resin fixative, dyes textile printing Magnesium acetate fixative, enzyme immobilization Glutaral Polyethylene imine fixative, enzyme immobilization food Cellulose triacetate Periodic acid fixative, essential oils Hydroabietyl alcohol fixative, essential oils/perfumes Tri ch I oromethyl phenyIcarbi nyI acetate fixative, fiber reactive dyes textiles Dimethylamine/epichlorohydrin/ethylenediamin e copolymer... 

Triacetate fiber n. A manufactured fiber produced from cellulose triacetate in the forms of filament yarn, staple, and tow. Cellulose triacetate fiber differs from acetate fiber in that during its manufacture the cellulose is completely acetylated whereas acetate, which is diacetate, is only partially acetylated. A fiber may be called triacetate when not less than 92% of the hydroxyl groups are acetylated. Fabrics of triacetate have higher heat resistance than acetate fabrics and can be safely ironed at higher temperatures. Triacetate fabrics that have been properly heat-set (usually after dyeing) have improved ease-of-care characteristics because of a change in the crystalline structure of the fiber. Complete textile glossary. Celanese Acetate EEC, New York, 2000. Also see acetate fiber. 

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