Polyesters spinning

P.B.15 3, like stabilized a-Copper Phthalocyanine Blue, markedly affects the hardening of unsaturated polyester cast resins. The list of applications also includes PUR foam materials, office articles, such as colored pencils, wax crayons, and water colors, as well as spin dyeing of polypropylene, polyacrylonitrile, secondary acetate, polyamide, polyester, and viscose. Used in polyester spin dyeing, P.B.15 3 satisfies the thermal requirements of the condensation process (Sec. 1.8.3.8). 1/3 and 1/25 SD samples equal step 7-8 on the Blue Scale for lightfastness. Textile fastnesses, such as stability to wet and dry crocking are perfect. 

P.V.29 is also used in polyester spin dyeing. It meets the high thermal demands of the condensation process, during which the pigment is exposed to 290°C for 5 to 6 hours. At 1/3 and 1/9 SD, the systems equal step 7 to step 8 on the Blue Scale for lightfastness. P.V.29 performs excellently in terms of the more important textile fastnesses, such as fastness to wet and dry crocking. 

The magnitude of this error has been estimated through numerical solution of the full partial differential equations, as discussed below, and the two temperatures can differ by 5 °C under typical polyester spinning conditions. 

A few examples for a polyester spin-draw winding process will show this, and hopefully give an impression of how melt-spinning machines are designed. 

To produce a spandex fiber by reaction spinning, a 1000—3500 molecular weight polyester or polyether glycol reacts with a diisocyanate at a molar ratio of about 1 2. The viscosity of this isocyanate-terrninated prepolymer may be adjusted by adding small amounts of an inert solvent, and then extmded into a coagulating bath that contains a diamine so that filament and polymer formation occur simultaneously. Reactions are completed as the filaments are cured and solvent evaporated on a belt dryer. After appHcation of a finish, the fibers are wound on tubes or bobbins and rewound if necessary to reduce interfiber cohesion. 

Mechanical Properties. Polyester fibers are formed by melt spinning generally followed by hot drawing and heat setting to the final fiber form. The molecular orientation and crystalline fine stmcture developed depend on key process parameters in all fiber formation steps and are critical to the end use appHcation of the fibers. 

Synthetic Fiber and Plastics Industries. In the synthetic fibers and plastics industries, the substrate itself serves as the solvent, and the whitener is not appHed from solutions as in textiles. Table 6 Hsts the types of FWAs used in the synthetic fibers and plastic industries. In the case of synthetic fibers, such as polyamide and polyester produced by the melt-spinning process, FWAs can be added at the start or during the course of polymerization or polycondensation. However, FWAs can also be powdered onto the polymer chips prior to spinning. The above types of appHcation place severe thermal and chemical demands on FWAs. They must not interfere with the polymerization reaction and must remain stable under spinning conditions. 

Fig. 2. Ultrafine fibers are produced by spinning bicomponent or biconstituent polymer mixtures, highly stretching such products to ultrafine deniers, and extracting or otherwise removing the undesked matrix carrier to release the desked ultrafine fibers (30). For example, spinning polyester islands in a matrix of polystyrene and then, after stretching, dissolving the polystyrene to leave the polyester fibers cospinning polyester with polyamides, then stretching,...

Microdenier nylon and polyester were a significant spinning breakthrough when demonstrated in 1985. The finer-than-silk fibers added a new dimension to fabric aesthetics, comfort, and performance. Microdenier nylons are used in weaving, warp knits, and weft knits for sports-, leisure-, and... 

The alkaline solutions can remove water-soluble polymers in the spinning mix and inert products such as titanium dioxide. Basic treatments can also hydroly2e a certain amount of the polyester itself. For some silk-like appHcations or for producing fine denier fabrics, this basic treatment can produce a 10—30% weight loss of polyester (190,196). Certain polyesters such as anionically modified polyester can undergo more rapid weight loss than regular polyester (189). 

Carpet. Carpet, an important textile, may also be treated to provide water and oU repeUency however, the principal functions of the current carpet treatments are to provide soU and stain resistance. High quaUty carpets, especiaUy those made from nylon, polyester, or wool, have a significant proportion of the surface coated with fluorochemical materials. The treatments can be spray-appUed to a finished carpet or appUed directly to the fiber during the spinning or dyeing operations. Suitable fluorinated resin materials are readily avaUable from 3M or DuPont. 

Steam-heated aluminum castings are used for the melt spinning of nylon and polyester fibers and have been used for storage of raw materials during manufacturing, as well as for storage of acetic acid in cellulose acetate plants. 

Melt spinning polyesters is preferred to solution spinning because of its lower cost. Due to the hydrophobic nature of the fiber, sulfonated terephthalic acid may be used as a comonomer to provide anionic sites for cationic dyes. Small amounts of aliphatic diacids such as adipic acid may also be used to increase the dyeability of the fibers by disturbing the fiber s crystallinity. 

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