Fibers acrylic

The nature and distribution of acrylonitrile and comonomer or comonomers in the acrylic fibers affect the overall dyeability and the classes of dyes that may be used in dyeing these fibers. Both acrylic and modacrylic fibers can be dyed using disperse dyes, with the more hydrophobic and less crystalline modacrylic being more dyeable with this dye class. The polar cyanide groups in the acrylonitrile unit of these fibers have some affinity for acid dyes and particularly mordanted systems containing copper or chromium ions. Addition of an acid or basic comonomer such as acrylic acid or vinyl pyridine as comonomer imparts improved dyeability with basic and acid dyes, respectively, for these fibers. Vat dyes can be used on acrylic fibers to a limited extent. 

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Highly colored, they have been used to dye cellulose acetate (552) and acrylic fibers (553). Cationic dyes prepared from 2-azothiazoles by simple alkylation on the ring nitrogen (552) have been used increasingly with the introduction of polyacrylonitrile fibers with basic sites that can be colored with such dyes (554). 

Orange dye that gives on qiiaternizalion a new fast-ted dye oti acrylic fibers... 

PROPENE The major use of propene is in the produc tion of polypropylene Two other propene derived organic chemicals acrylonitrile and propylene oxide are also starting materials for polymer synthesis Acrylonitrile is used to make acrylic fibers (see Table 6 5) and propylene oxide is one component in the preparation of polyurethane polymers Cumene itself has no direct uses but rather serves as the starting material in a process that yields two valuable indus trial chemicals acetone and phenol... 

An important nitrile is acrylonitrile H2C=CHCN It is prepared industrially from propene ammonia and oxygen m the presence of a special catalyst Polymers of acryl omtrile have many applications the most prominent being their use m the preparation of acrylic fibers... 

Carbon and Graphite Fibers. Carbon and graphite fibers (qv) are valued for their unique combination of extremely high modulus and very low specific gravity. Acrylic precursors are made by standard spinning conditions, except that increased stretch orientation is required to produce precursors with higher tenacity and modulus. The first commercially feasible process was developed at the Royal Aircraft Fstablishment (RAF) in collaboration with the acrylic fiber producer, Courtaulds (88). In the RAF process the acrylic precursor is converted to carbon fiber in a two-step process. The use of PAN as a carbon fiber precursor has been reviewed (89,90). 

Aloisture Absorbent Synthetic Paper. Processes for making a water absorbent synthetic paper with dimensional stabihty have been developed by several companies. In a process developed by Mitsubishi Rayon, acrylic fiber is insolubilized by hydra2ine and then hydroly2ed with sodium hydroxide. The paper, formed from 100 parts fiber and 200 parts pulp, has a water absorption 28 times its own weight (96). Processes for making hygroscopic fibers have also been reported in the patent Hterature. These fibers are used in moisture absorbing nonwovens for sanitary napkins, filters, and diapers. 

B. G. Fmshour and R. S. Knorr, "Acrylic Fibers," iu M. Lewiu and EH M. Pearce, eds. Handbook ofFiberSdence and Technology, Vol. IV, Fiber Chemisty, Marcel Dekker, Inc., New York, 1985. 

Vinyl Bromide. Vinyl bromide [593-60-2] is prepared by the base-promoted dehydrobromination of ethylene dibromide [106-93 ]. It is used as a comonomer in the production of acrylic fibers. 

Process. Any standard precursor material can be used, but the preferred material is wet spun Courtaulds special acrylic fiber (SAF), oxidized by RK Carbon Fibers Co. to form 6K Panox B oxidized polyacrylonitrile (PAN) fiber (OPF). This OPF is treated ia a nitrogen atmosphere at 450—750°C, preferably 525—595°C, to give fibers having between 69—70% C, 19% N density less than 2.5 g/mL and a specific resistivity under 10 ° ohm-cm. If crimp is desired, the fibers are first knit iato a sock before heat treating and then de-knit. Controlled carbonization of precursor filaments results ia a linear Dow fiber (LDF), whereas controlled carbonization of knit precursor fibers results ia a curly carbonaceous fiber (EDF). At higher carbonizing temperatures of 1000—1400°C the fibers become electrically conductive (22). 

Other textile fibers include nylon, polyacrylonitrile, and ceUulose acetate (see Fibers, acrylic Fibers, cellulose esters Fibers, polyamide). 

Fig. 4. Carbocychc azo dyes. Disperse Yellow 3 [2832-40-8] (Cl 11855) (26) is used to dye polyester Reactive Orange 1 [6522-74-3] (Cl 17907) (27) is a cotton dye Direct Orange 26 [25188-23-2] (Cl 29150) (28) is a dye for paper Synacril Fast Red 2G [48222-26-0] (Cl 11085) (29) dyes acrylic fibers Acid...

Gellulosic—Acrylic Fibers. Commonly this blend is used ia koitgoods, wovea fabrics for slacks, drapery, and upholstery fabrics. Siace anionic direct dyes are used for the ceUulosic fiber and cationic dyes for the acryHcs, a one-bath dyeiag process is only suitable for light to medium shades. Auxiliaries are needed to prevent precipitation of any dye complexes. 

Wool—Acrylic Fibers. This blend is being used for iadustrial and hand knitting yams. The acryHc fiber is aesthetically similar to wool, iacreases the strength of the yam, and adds bulk to the goods. Special precautions are necessary siace the two fibers are colored with dyes of opposite ionic type. Coprecipitation is prevented with the use of an antiprecipitant. Usually, level dyeing acid dyes are used for the wool portion in combination with the cationic dyes for acryHc fiber. 

Polyester Fibei Acrylic Fiber Blends. This fiber blend is dyed ia a similar fashion to that of the blends of the different polyester fibers. The selection of cationic dyes is substantially larger for the acryhc blend. 

The as-spun acrylic fibers must be thermally stabilized in order to preserve the molecular structure generated as the fibers are drawn. This is typically performed in air at temperatures between 200 and 400°C [8]. Control of the heating rate is essential, since the stabilization reactions are highly exothermic. Therefore, the time required to adequately stabilize PAN fibers can be several hours, but will depend on the size of the fibers, as well as on the composition of the oxidizing atmosphere. Their are numerous reactions that occur during this stabilization process, including oxidation, nitrile cyclization, and saturated carbon bond dehydration [7]. A summary of several fimctional groups which appear in stabilized PAN fiber can be seen in Fig. 3. 

Capone, G. J., Wet-spinning technology. In Acrylic Fiber Technology and Applications, ed. J. C. Masson. Marcel-Dekker, New York, 1995, pp. 69 103. 

Acrylonitrile is mainly used to produce acrylic fibers, resins, and elastomers. Copolymers of acrylonitrile with butadiene and styrene are the ABS resins and those with styrene are the styrene-acrylonitrile resins SAN that are important plastics. The 1998 U.S. production of acrylonitrile was approximately 3.1 billion pounds. Most of the production was used for ABS resins and acrylic and modacrylic fibers. Acrylonitrile is also a precursor for acrylic acid (by hydrolysis) and for adiponitrile (by an electrodimerization). 

Acrylic fibers are a major synthetic fiber class developed about the same time as polyesters. Modacrylic fibers are copolymers containing between 35-85% acrylonitrile. Acrylic fibers contain at least 85% acrylonitrile. Orion is an acrylic fiber developed by DuPont in 1949 Dynel is a modacrylic fiber developed by Union Carbide in 1951. 

Acrylic fibers are characterized by having properties similar to wool and have replaced wool in many markets such as blankets, carpets, and sweaters. Important properties of acrylics are resistance to solvents and sunlight, resistance to creasing, and quick drying. 

Acrylic fiber breaking strength ranges between 22,000 and 39,000 psi and they have a water absorption of approximately 5%. Dynel, due to the presence of chlorine, is less flammable than many other synthetic fibers. 

Major uses of acrylic fibers are woven and knitted clothing fabrics (for apparel), carpets, and upholstery. 

Cellulosic, polyester, and acrylic fibers lubricated with a surfactant-based oiling composition containing an organic phosphorus ester neutralized with an amine showed less pilling, good antistatic properties, and anticorrosiveness. The phosphorus ester salts were hexyl phosphate trimethylamine salt, dodecamethy-lene caproate phosphonate ethylamine salt, and polyethylene glycol dodecyl ether phosphate dimethylamine salt [262]. 

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