In daily life, polyester fiber is a chemical substance that contains organic dibasic acids and polyester components. It usually appears on fabrics or clothing. Since polyester fiber can be used to make spun fabrics, people use polyester fiber to make them. Long-term contact with polyester fiber can easily produce harmful substances to the human body, which is very bad for the body. Is polyester harmful to the body? A general term for fibers made from polyesters generated by condensation of various diols and aromatic dicarboxylic acids or their esters. Specific varieties include: polyethylene terephthalate fiber, polybutylene terephthalate fiber, polypropylene terephthalate fiber, poly-1,4-cyclohexanedimethyl terephthalate fiber, poly-2,6-naphthalene dicarboxylic acid fiber, and various modified polyethylene terephthalate fibers (such as: CDP, ECDP, EDDP), etc. Since polyethylene terephthalate fiber is the main variety, polyester fiber is usually referred to as this fiber. This type of fiber has a crisp appearance and good thermal stability, but slightly poor hygroscopicity. They are mainly used to make various clothing items, bedding items, interior decoration items, etc.; some individual varieties such as polyethylene 2,6-naphthalate fiber are mainly used in industry. Harmful to the body Recycled polyester Regenerated fibers are mainly divided into two categories: regenerated cellulose fibers and regenerated synthetic fibers. Viscose fiber is the earliest regenerated fiber, and later new regenerated cellulose fibers such as Lyocell fiber, cellulose carbamate fiber, superconducting viscose fiber, kapok fiber and bamboo fiber appeared one after another. Polyester fiber accounts for about 70% of synthetic fibers, and the application of polyester in the bottle industry is rapidly expanding, so recycled synthetic fibers are mainly recycled polyester fibers. Domestic recycled polyester fiber is in the research and small-scale industrial trial stage Polyester Synthesis The production process of polyester includes two parts: polyester melt synthesis and melt spinning. The raw materials for synthetic polyester are polyethylene terephthalate and ethylene glycol, which are mainly obtained from petroleum cracking, but can also be obtained from coal and natural gas. Petroleum is heated and cracked to obtain toluene, xylene and ethylene, etc. After chemical processing, terephthalic acid or dimethyl terephthalate and ethylene glycol can be obtained. In the early days of polyester production, dimethyl terephthalate and ethylene glycol were used as raw materials because terephthalic acid was difficult to purify. The successful refining of terephthalic acid in 1965 reduced the number of steps in polyester production and reduced costs. The production of polyester using terephthalic acid and ethylene glycol as raw materials has increased year by year. Polycondensation: Dimethyl terephthalate and ethylene glycol are transesterified to produce diethylene terephthalate oligomers, which are polycondensed at 280-290°C under vacuum conditions to obtain polyethylene terephthalate; or terephthalic acid and ethylene glycol are directly esterified, and then ethylene terephthalate is polycondensed to obtain a polyester melt. The polyester melt can be used to prepare polyester chips and melt direct spinning. Polyester chips are obtained by casting and pelletizing polyester melt. Spinning After drying and melting, polyester chips can be used for spinning, preparing polyester films, polyester bottles, etc. During the melting process, slice The moisture contained can cause the polyester to hydrolyze and affect the spinning performance and fiber quality. Therefore, the chips must be dried before spinning to reduce the moisture content to below 0.01%. In chip spinning, the dried polyester chips are heated and melted in the screw, extruded into various spinning positions of the spinning box, and then accurately metered and filtered by a metering pump before being ejected from the spinneret holes of the spinneret. The diameter of the spinneret hole is generally 0.15 to 0.30 mm. The ejected melt stream is cooled and solidified into filaments by the cooling air flow. |
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