Do you know the production method of acrylic fabric?

Acrylic fiber has properties very similar to wool, with good elasticity. When extended by 20%, its rebound rate can still maintain 65%. It is fluffy, curly, and soft, with a warmth retention 15% higher than wool. It is known as synthetic wool. The strength ranges from 22.1 to 48.5 cN/tex, which is 1-2.5 times higher than wool. Excellent sun resistance, exposed to open air for one year, the strength only decreases by 20%, and can be made into curtains, curtains, tarpaulins, cannon coats, etc. Can withstand acid, oxidants, and general organic solvents, but has poor alkali resistance. The fiber softening temperature is 190-230 ℃.

Production methods

Acrylic fiber is known as artificial wool. It has the advantages of softness, swelling, easy dyeing, bright color, light resistance, antibacterial properties, and no fear of insect infestation. According to the requirements of different uses, it can be pure spun or blended with natural fibers. Its textiles are widely used in fields such as clothing, decoration, and industry.

Acrylic fiber requires a high purity of the raw material acrylonitrile, and the total content of various impurities should be less than 0.005%. The second monomer of polymerization is mainly made of methyl acrylate, which can also be methyl methacrylate, with the aim of improving spinnability, fiber feel, softness, and elasticity; The third monomer is mainly used to improve the dyeing properties of fibers, generally including itaconic acid containing weak acidic dyeing groups, sodium propylene sulfonate, sodium methacrylate sulfonate, sodium p-methylacrylamide benzenesulfonate containing strong acidic dyeing groups, and methyl vinyl pyridine containing alkaline dyeing groups.
polymerization

The polymerization process is divided into two categories: suspension polymerization with water as the medium and solution polymerization with solvent as the medium. The polymer obtained from suspension polymerization precipitates in flocculent form and needs to be dissolved in a solvent to prepare a spinning solution. The solvent used for solution polymerization can dissolve both monomers and polymers, and the resulting polymerization solution is directly used for spinning. The solvents used for solution polymerization include dimethyl formamide, dimethyl sulfoxide, sodium thiocyanate, and zinc chloride. The polymerization time using the first two organic solvents is generally more than 10 hours, but the concentration of the spinning solution is high due to its strong solubility. The spinning speed can be appropriately increased, and the solvent recovery is also relatively simple. The resulting fibers have good performance, and the material requirements for the equipment are relatively low; Using the latter two inorganic solvents, the polymerization time only takes 2 hours, resulting in better fiber whiteness.

spinning

The spinning solution is generally a polyacrylonitrile polymer with an average molecular weight of 53000-106000. Its fiber whiteness is good, with a thermal decomposition temperature of 200-250 ℃ and a melting point of 320 ℃. Therefore, acrylic fibers are produced by wet spinning and dry spinning using high polymer solutions. The concentration of spinning solution in dry spinning is 25% to 30%, and the spinning speed is fast. However, due to the slow solidification of the fine flow sprayed by the spinneret, it is easy to bond before solidification. A spinneret with a large number of pores cannot be used. The spinning solvent is only dimethyl formamide, and the resulting fiber structure is uniform and dense, suitable for weaving silk like fabrics. Wet spinning is suitable for producing short fibers, which are fluffy and soft, and suitable for weaving woolen like fabrics. In addition to the solvents used for solution polymerization, the spinning solvents used also include dimethylacetamide, vinyl carbonate, nitric acid, etc. Most solvents have high boiling points and are not easy to evaporate during the spinning process. In the 1980s, research was conducted on the use of melt spinning method for acrylic fibers, using water as a plasticizer for polymers. Without the need to prepare polymer solution, solvent recovery and circulation systems were eliminated, and the physical properties of fibers were basically the same as those obtained by dry or wet spinning. They have now entered the intermediate experimental stage.