New Plastic Packaging Material PEN

PEN Characteristics The resin structure of PEN is very similar to that of PET. PET's benzene ring is substituted with naphthalene ring is PEN.
Because the naphthalene ring has a more conjugated structure than the benzene ring, the molecule has high rigidity and a more planar structure. Although the two have similar characteristics, the performance of the PEN is better than PET in all aspects. It has the following characteristics: 1 ) PEN's heat distortion temperature is 30°C higher than PET and can be used for hot filling. 2) The glass transition temperature of PEN is about 40°C higher than that of PET, and the tensile strength, flexural modulus, and bending strength are also high. Therefore, PEN has good dimensional stability, low thermal shrinkage, and good long-term heat resistance; 3) PEN It is superior to PET in acid and alkali resistance, hydrolysis resistance and general chemical resistance. 4) PEN is a kind of good gas barrier property in various plastics. The barrier properties to oxygen, carbon dioxide and water are 4 times, 5 times, and 3.5 times higher than those of PET respectively. 5) Compared to PET, PEN is an organic solvent. The adsorptivity is small, and it is free and has low precipitation property. 6) PEN crystallinity is lower than PET, easy to obtain thick-walled transparent bottles; 7) PEN has good UV resistance; 8) PEN has good hygienic properties, the US Food and Drug Administration (FDA) has allowed PEN to be used Food packaging.

PEN/PET copolymerization or blending As noted above, PEN has excellent properties and is an ideal packaging material. However, PEN's price is high, which limits its wide application as a packaging material. Since both PEN and PET are thermoplastic polyesters and their chemical structures are similar, a certain ratio of PEN and PET are melt-blended to form a polymer alloy, which can take into account the economics of PET and the heat resistance and resistance of PEN. The excellent characteristics such as gas properties are the focus of the development of PEN application research, and it is also one of the main ways to bring PEN to market (especially in the packaging field). When 10%-20% of PEN is blended with PET, the barrier properties to oxygen and carbon dioxide can be increased by 30%-50% and 23%-37%, respectively, and the shielding wavelength of ultraviolet rays can be increased to 380 nm. PEN/PET blends or copolymers have been used for the packaging of edible oils, alcoholic beverages, carbonated soft drinks, and beer.

PEN's application in the packaging industry PEN first appeared on the market as a film product, but at present, bottle packaging containers have become the main application market for PEN.

Films <br> Currently Teijin, ICI, and Shell Chemicals have officially sold PEN films. Teijin is a world leader in the production of biaxially oriented PEN films. As early as 1989, it successfully developed high-performance PEN films. In 1993, it built a 4,000-ton/year film production line. In addition, world film giants such as Toray and Du Pont have also entered the PEN film production market. PEN can be manufactured using the same equipment as PET. The process is the same as PET film production. PEN film (BOPEN) is produced by melt-extrusion-biaxial stretching. BOPEN has excellent characteristics such as heat resistance, gas barrier property, hydrolysis resistance, dimensional stability, etc., and it is easy to obtain an extremely thin film with a thickness of 0.8 μm. By using these characteristics of the film, packaging materials for different purposes can be obtained. Among them, there is a large market for application in food packaging, pharmaceutical packaging, fragrant packaging, and impulse-resistant packaging for precision instruments.

PEN Packaging Containers <br> Currently, bottle packaging containers have become PEN's main market. Due to the excellent properties of PEN, PEN bottles blown with PEN perform better than PET bottles. PEN bottle transparent, hot filling temperature up to about 100 °C, UV, oxygen, carbon dioxide barrier Deng, and chemical resistance, used in beverages, beer, cosmetics, baby food packaging, has great practicality and market . Although PEN bottles can be processed by various blow molding methods of PET, the most commonly used is stretch blow molding.

Domestic Status and Development Prospects <br> PEN, a functional polyester with naphthalene as framework, has become a hot spot for many foreign large companies to compete for development with an annual output of more than 100,000 tons and has been widely used in product packaging. , construction, electronics, electrical appliances, aerospace, textiles and other fields. In contrast, domestic development of PEN is in its infancy, and a lot of work needs to be done from the synthesis of 2,6-NDC monomer, PEN performance characterization and applications. Yizheng Chemical Fiber Co., Ltd., Angang University, Guilin Electronics Research Institute and Beijing Chemical Research Institute have done some research work and made some progress. With the rapid development of other industries such as the packaging industry and the electronic communications industry, the demand for PEN will increase substantially, and China will also become a major consumer of PEN. In beer packaging only, the current total consumption of beer in mainland China ranks second in the total class cadre, beer packaging uses 35 billion beer bottles (including recycling bottles) and 7 billion cans annually, if there is 10% glass beer Replaced by plastic bottles, the demand for 4 billion, the market is huge. Therefore, it is very urgent to develop our own industry. Domestic related companies and research institutes should increase human and financial investment to accelerate the development of PEN technology and industrialization and to welcome the arrival of PEN consumption boom.