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Copolymerization modification of PET heat shrinkable polyester film-film supplier

by:POLYVA     2021-12-07
With the continuous development of China's plastic packaging industry and the continuous improvement of people's living standards, most of the beverages such as juice and soda are packaged in PET plastic bottles with excellent comprehensive performance, good barrier properties, non-toxic and tasteless, and their consumption is considerable. According to statistics, the current consumption of PET beverage bottles in the country is at least 250,000 tons, and the amount of PET heat-shrinkable label film used with it can reach 20,000 to 30,000 tons. In addition, since China's accession to the WTO, foreign trade has continued to expand. In order to improve the image and value of exported goods, higher-end packaging materials such as polyester heat-shrinkable film must also be used. In short, the application prospects of heat shrinkable PET film are very promising! Polyester film (PET film) is a crystalline material, and ordinary polyester film can only get a heat shrinkage rate of less than 30% after special processing. To obtain a polyester film with a higher heat shrinkage rate, it must be modified. In other words, in order to prepare a polyester film with a high thermal shrinkage rate, it is necessary to copolymerize and modify ordinary polyester, ie, polyethylene terephthalate. The highest heat shrinkage rate of the PET film modified by copolymerization can be as high as 70% or more. Ordinary polyester is generally prepared by esterification and polycondensation of terephthalic acid (PTA) and ethylene glycol (EG), and belongs to crystalline polymer (strictly speaking, it is a polymer in which crystalline and amorphous regions coexist) . The so-called copolymerization modification means that in addition to the two main components of terephthalic acid (PTA) and ethylene glycol (EG), the third or even fourth component is introduced to participate in the copolymerization, the purpose is to generate an asymmetric molecular structure. And the formation of amorphous PET copolymer. The third or even fourth monomer introduced can be a dibasic acid or a glycol. Among them, dicarboxylic acids include isophthalic acid, malonic acid, succinic acid, adipic acid, sebacic acid, etc.; dihydric alcohols include neopentyl glycol, propylene glycol, diethylene glycol, 1,4-ring Hexane dimethanol and so on. For example, when the dicarboxylic acid (Acidic) is used for copolymerization modification, the obtained PET copolymer is called APET; when the glycol (Glycolic) is used for copolymerization modification, the prepared PET copolymer is It is called PETG. Among the third monomers introduced above, the most commonly used dicarboxylic acid is isophthalic acid (IPA). The addition of IPA can change the symmetrical and tight structure of the polyester, destroy the regularity of the macromolecular chain, and reduce the inter-macromolecule The force of the polyester makes the polyester molecular structure more flexible. At the same time, due to the introduction of IPA, it is difficult for the polyester to nucleate and crystallize, and with the increase in the amount of IPA introduced, the APET copolymer transitions from partially crystalline to amorphous polymer. Because the crystallization ability of this modified polyester APET decreases, The amorphous area becomes larger, so it can be used to make high shrink films. The recommended amount of IPA is about 20%. The third monomer introduced may also be a glycol. The most commonly used diol is 1,4 cyclohexane dimethanol (CHDM). In the process of polyester copolymerization, adding CHDM will have a great impact on changing the Tg, Tm and crystallization rate of polyester. With the increase of CHDM content, the melting point of the copolyester PETG decreases, the glass transition temperature increases, and the copolymer becomes an amorphous structure. However, the addition amount of 1.4 cyclohexane dimethanol (CHDM) must be controlled within an appropriate range, and it is usually recommended that the addition amount of CHDM be 30-40%. The PETG modified with glycol can not only be used to prepare high-shrink films, but also can be used to produce heat-sealing films, high-transparency films, etc., with a wide range of uses. It is a company specializing in the production of PET film with multiple functions, such as: transparent PET film, milky white PET film, release PET film, supply of PET motor film, etc. With a wide variety of products, affordable prices, and environmental protection, we provide customers with excellent quality and service based on the service tenet of excellence in production, honesty and trustworthiness in distribution, and warm and thoughtful service. Interested parties welcome to inquire! Contact: Wen Feng 13728425799
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