Polyester fiber, commonly known as “polyester”. It is a synthetic fiber derived from polycondensation of organic diacid and dihydric alcohol. Polyester fiber most commonly refers to a type called PET fiber. PET fibers account for more than 60% of the world’s synthetic fiber production.
History:
In 1941, British J.R. Winfield and J.T. Dixon first successfully developed polyester fiber in the laboratory using terephthalic acid and ethylene glycol as raw materials and named it Terylene. In 1953, the United States produced polyester fibers with the trade name Dacron. Subsequently, polyester fibers have developed rapidly in countries around the world. In 1960, the world output of polyester fiber surpassed that of polyacrylonitrile fiber, and in 1972 it surpassed polyamide fiber, becoming the largest variety of synthetic fibers.
Performance:
Glass transition temperature: 67℃-81℃
High strength: the strength of the short fiber is 2.6-5.7cN/dtex, and the strength of the high-strength fiber is 5.6-8.0cN/dtex. The impact strength is 4 times higher than that of nylon and 20 times higher than that of viscose fiber, so polyester fabric products are quite strong and durable.
Good elasticity: The elasticity is close to that of wool. And when the elongation is 5% to 6%, it almost completely recovers. The wrinkle resistance exceeds other fibers, that is, the fabric does not wrinkle and has good dimensional stability. The elastic modulus is 22-141cN/dtex, which is 2 or 3 times higher than that of nylon.
Good abrasion resistance: The abrasion resistance is second only to nylon with the best abrasion resistance, and is better than other natural fibers and synthetic fibers.
Good light resistance: second only to acrylic. Its light fastness is better than that of natural fiber fabrics.
Corrosion Resistance: Resistant to bleaches, oxidants, hydrocarbons, ketones, petroleum products, and inorganic acids. Dilute alkali resistance, not afraid of mildew, but is decomposed by hot alkali.
Dyeing property: Polyester dyeing is poor, but the color fastness is good, and it is not easy to fade.
Hygroscopicity: The hygroscopicity is very small, the relative humidity is 100%, and the moisture absorption rate is only 0.6%~0.8%. It has poor moisture absorption. And it is easy to wash and can be quickly dried. However, it is sultry to wear, easy to carry static electricity, and affects appearance and comfort.
Synthesis Process:
The production process includes polyester melt synthesis and melts spinning. The raw materials for synthesizing polyester are polyethylene terephthalic acid and ethylene glycol, which are mainly obtained from petroleum cracking, and can also be obtained from coal and natural gas. Toluene, xylene, and ethylene are obtained by thermal cracking of petroleum, and terephthalic acid or dimethyl terephthalate and ethylene glycol can be obtained after the chemical processing of polyester chips. In the early production, dimethyl terephthalate and ethylene glycol were used as raw materials because terephthalic acid was not easily refined. In 1965, the refining of terephthalic acid was succeeded, which reduce the production process and cost. Polyester produced with terephthalic acid and ethylene glycol as raw materials have increased year by year.
Polycondensation is the transesterification of dimethyl terephthalate with ethylene glycol. And the resulting diethylene terephthalate oligomer is polycondensed at 280-290°C under vacuum conditions to obtain polyethylene glycol terephthalate. And then ethylene terephthalate is polycondensed to obtain polyester melt. The melt can be used to produce polyester chips or directly spin. Polyester chips are obtained by casting and dicing.
Modification:
Its properties are improved by physical and/or chemical methods, commonly known as a polyester modification. The improvement is divided into two directions, one is to improve the performance of natural fibers, and the other is to improve the inherent excellent properties of polyester fibers and give full play to their specialties.
Cationic dye-dyeable polyester (CDP): A third monomer containing an anionic group is introduced for copolymerization during PET synthesis.
Easy cationic dye-dyeable polyester (ECDP) fiber: On the basis of adding a third monomer, a flexible fourth monomer is added to develop and produce an easy cationic dye-dyeable copolyester, which can be dyed at normal pressure.
Easily hydrolyzed polyester (COPET): In the production of conventional polyester, a copolyester is produced by adding a variety of copolymerization components. It can be dissolved in a dilute alkaline solution at a temperature of 100 °C.
High-shrinkage polyester (HSPET) fiber: Copolymerized modified polymer adopts further physical modification method combined with high tensile and low-temperature settings. The shrinkage rate in boiling water can reach more than 50%.
Low melting point polyester (LPET) and fiber: It is obtained by adding copolymerization components (IPA, adipic acid, DEG, 1.4-BG, 1.6-HD, PEG, etc). Its melt point is lower than regular fibers, which can meet the requirements of different thermal bonding temperatures.
Flame retardant polyester fiber: Flame retardant additives are added in the polymerization or spinning process, mainly using phosphorus-containing and halogen-containing compounds.
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