Cellulose acetate spinning

Formation of cellulose acetate, spinning into fibre and subsequent hydrolysis into cellulose. 

Kiefer, J.E. and Touey, G.P. "Cellulose Acetate Spinning Solutions and Process of Spinning Fine Denier Filaments," US Patent 3,033,698(1962). 

Cellulose acetate [9004-35-7], prepared by reaction of cellulose with acetic anhydride, acetic acid, and sulfuric acid, is spun into acetate rayon fibers by dissolving it in acetone and spinning the solution into a column of warm air that evaporates the acetone. Cellulose acetate is also shaped into a variety of plastic products, and its solutions are used as coating dopes. Cellulose acetate butyrate [9004-36-8], made from cellulose, acetic anhydride, and butyric anhydride in the presence of sulfuric acid, is a shock-resistant plastic. 

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. 

Fig. 7. A C-13 relaxation time measurement of solid state wetted cellulose acetate (6% by weight water) using the inversion recovery (IR) method at 50.1 MHz and spinning at 3.2 kHz at the magic angle (54.7 deg) with strong proton decoupling during the aquisition time (136.3 ms), (upper part of the Figure). Tau represents the intervals between the 180 deg (12.2 us) inverting and 90 deg (6.1 us) measuring pulse. 2200 scans were collected and the pulse delay time was 10 s, Cf. Table 3 and Ref.281...

Acetate A general name for processes for making cellulose acetate fibers. Cellulose is acetylated, dissolved in acetone, and spun into fibers by injecting through orifices into heated chambers. Cellulose mono-acetate is made by acetylating with a mixture of acetic acid, acetic anhydride, and sulfuric acid as the catalyst. Cellulose tri-acetate is made in a similar fashion, but using perchloric acid as the catalyst, and dry-spinning from a solution in ethanol/ methylene chloride. Cellulose tri-acetate fibers were first made commercially by Courtaulds in London in 1950. 

Wet spinning. This technique is characterized by spinning a filtered viscous polymer mass, dissolved in a suitable solvent, into contact with a precipitation or coagulation bath. Polyacrylonitrile, polyvinyl acetate, cellulose acetate, and other materials are processed by this method. Thermal requirements for pigments are less stringent than for melt spinning but pigments are expected to be fast to the solvents and chemicals used. 

The textiles printing industry has an appreciable interest in P.Y.17 and applies it in the form of pigment preparations. Where its fastness properties satisfy the specifications and where the use requirements are not too demanding, the pigment is also utilized for spin dyeing purposes. Manufacturer recommendations include media such as polyacrylonitrile and cellulose acetate fibers, on which 1/3 SD pigment prints exhibit a lightfastness which is equal to step 5 on the Blue Scale. 

Cellulose Acetate and Triacetate Fibers. Polymer solutions arc convened into fibers by extrusion. The dry-extrusion process, also called dry spinning, is primarily used lor acelate and triacetate. 

Cellulose acetates are by far the most important organic esters. The diacetate has DS = 2.4 and is fabricated either in filament form for fibres or in powder form to melt. Diacetate filaments are obtained by dissolution in acetone, extrusion through a spin and then evaporation of the solvent. The obtained fibres are used in textiles (called simply acetate ) and in cigarette filters (tow). The triacetate (DS = 2.9) finds application in brilliant textiles easy to dye. 

The method used for spinning cellulose acetate is dry spinning. The dope is heated... 

The spinnerette is stainless steel, and because the filaments must be heated and prevented from sticking together, and because space must be allowed for the escape of acetone vapor, the holes must be kept farther apart than those of the spinnerettes used for wet spinning. As the hot solution of cellulose acetate in acetone emerges downward into the spinning cabinet, an instantaneous loss of acetone takes place from the surface of the filaments, which tend to form a solid skin over the still liquid or plastic interior. A current of air, either in the direction the filaments are moving or countercurrent, heats the filaments, and as the acetone is diffused from the center through the more solid skin, each filament collapses to form the indented cross-sectional shape typical of cellulose... 

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