Progress and application of the hottest transparen

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Progress and application of transparent PP

Abstract: the development status of transparent PP at home and abroad and the research progress of transparent modifiers are reviewed; By comparing the properties of transparent polypropylene with ordinary polypropylene and transparent materials, the stroke value displayed on the display screen introduces the advantages and application fields of transparent polypropylene, and puts forward development suggestions

key words: transparent polypropylene transparent modifier development and application

. Polypropylene (PP) has excellent characteristics such as good mechanical properties, non-toxic, low relative density, heat resistance, chemical resistance, easy processing and molding, and low price. It has become the fastest growing and most active variety of new products among the five general synthetic resins. PP is a partially crystalline resin. Under normal processing conditions, the crystallization of PP is low, making the product less transparent. In order to develop PP, it is necessary to carry out antireflection modification on PP. The performance of transparent modified PP is more outstanding, especially its excellent transparency and gloss can be comparable with typical transparent materials (such as pet, PVC, PS, etc.). Transparent PP also has a higher thermal deformation temperature (generally higher than 110 ℃, and some can reach more than 130 ℃), while the thermal deformation temperature of pet, PVS, PS and other materials is lower than 90 ℃, so transparent PP has a broader application range than pet, PS, PVS and other materials. Therefore, it has developed rapidly in the world in recent years, and has been widely used in medical devices, transparent packaging, household products and other fields with high requirements for transparency. Various transparent PP brands are a bright spot in the recent development of PP new products

. At present, PP resin can improve its transparency mainly through the following three ways: ① using PP products with excellent transparency - random copolymers; ② Using transparent modifier (a nucleating agent), such as the transparent modifier produced by sorbitol, and adding 0.1% - 0.4% transparent modifier additive can not only improve the transparency and rigidity of PP, but also broaden the melting range; ③ For PP produced with metallocene catalyst, if the transparency of pet is set at 100%, the transparency of metallocene PP random copolymer can reach 96%

1 progress of transparent PP

1 1 development of transparent PP abroad

. Transparent PP and its application were developed earlier and developed faster abroad. According to miliken chemical company of the United States, transparent PP has been widely used in various transparent products in the United States, such as fruit boxes, beverage bottles, films, syringes, microwave cookers, etc., and the growth rate of transparent products is 7% - 9% higher than that of ordinary PP products [1]. According to Nippon physicochemical Corporation, 7% of PP in Japan is transparent PP, and the output of transparent PP is more than 400kt/A. The consumption of microwave ovens, cookers and furniture in Japan's transparent PP market is also in positive proportion to the elastic deformation. The transparent PP with the same transparency and gloss as PVC is manufactured by Japan's Chuguang chemical company. Now it can widely replace the packaging materials such as stationery and notebook made of ordinary transparent PVC. The price is only equivalent to 20% - 30% of PVC. In 1999, 1200t transparent PP was sold. LG Caltex of South Korea introduced transparent PP to the market as a substitute for pet, which is used in the packaging of water bottles, detergent bottles, personal care products and so on. Fina's marketing department claimed that their new transparent PP products would enter PS food packaging with a market capacity of 300kt/A. Novolen 3248tc, a PP random copolymer from BASF company in Germany, has high fluidity, melt flow index of 48g/10min, and low warpage performance, transparency of 90% and haze of 10%, which is suitable for thin-walled packaging and daily necessities. PP random copolymer ELTEX pkl176 developed by Solvay company, containing ethylene and transparent agent, is mainly used to manufacture single-layer transparent bottles and extruded sheets, which can be hot pressed into various containers and decorations. Its products have glassy luster, good chemical stability, environmental stress cracking resistance and impact strength. Some companies also use metallocene catalysts to produce highly transparent PP resin. Although the optical properties of this kind of transparent PP are equivalent to or even better than those of PP with transparent agent, there is still a certain distance in production cost and molding processing, so there are few such transparent PP in the market [2]

in short, with the development and continuous improvement of transparent PP, the market demand is rising rapidly, as shown in table 1[3]. The total market capacity of the world in 2001 can reach 1500 ~ 1600 kt/A, and the market demand is expected to reach 2000 ~ 2500 kt/A in 2005

1.2 the development of transparent PP in China

2 transparent modifier

the development of transparent PP at the same time promotes the development of transparent modifiers at home and abroad

2.1 the antireflection principle of transparent modifier

. Transparent modifier is a nucleating agent and a new functional additive that conforms to the development of PP modification. It is generally believed that the addition of transparent modifier improves the crystallization speed of PP in the cooling process and reduces the spherulite size of PP. it is a small molecular substance that can promote crystallization. It plays the role of crystal nucleus in the resin, turning the original homogeneous nucleation into heterogeneous nucleation, increasing the number of crystal nuclei in the crystallization system, increasing the number of microcrystals, reducing the number of spherulites, and thinning the crystal size. When the size of spherulites is smaller than the wavelength of visible light, light is hardly refracted and reflected at the crystal interface, and the transparency and surface gloss are significantly improved

2.1 progress of transparent modifier abroad

2.3 development of transparent modifiers in China

in recent years, the development and application of transparent agents in China have developed rapidly. Many enterprises are engaged in the development and research of transparent agents. The price of these products is far lower than that of foreign products, but the variety and quality stability need to be improved. At present, transparent agents used by transparent PP manufacturers are still mainly imported. To adapt to the rapid development of the plastic industry in the future, a lot of work needs to be done in terms of product structure, internal quality and scale efficiency, especially the development and production of high-efficiency transparent agents, which should become the focus of future development

3 performance and application of transparent PP

3 1 performance comparison between transparent PP and ordinary PP

. Compared with ordinary PP, the comprehensive performance of transparent PP is improved, and the results are shown in Table 3. It can be seen from table 3 that the nucleation density, crystallization temperature, Vicat softening point and hardness of transparent PP are effectively improved due to the addition of transparent agent; A large number of crystal nuclei lead to extreme homogenization of crystal structure, which significantly improves the transparency and surface gloss. The improvement of these comprehensive properties enhances the environmental adaptability of transparent PP products and expands the scope of use [6]

3.2 comparison of properties between transparent PP and other materials

. Compared with some other materials, transparent PP is light in weight and low in price, with good comprehensive properties of rigidity and strength, moisture resistance and recyclability. With the launch of transparent PP, it has broken through the bottleneck of poor transparency of PP products and become a strong competitor of transparent materials, as shown in Table 4

3.3 application of transparent PP

. Transparent PP resin can replace other expensive resins, expand the use of products, reduce costs and improve work efficiency. From the perspective of end use, transparent PP has been widely used in medical syringes, food containers, stationery, films, plates, boxes, bottles, household containers, all kinds of packaging, etc. From the perspective of forming method, the application fields are shown in Table 5

4 conclusion

. Transparent PP has become a bright spot in the development of new PP products at home and abroad because of its wide application fields. Development of transparent PP in China

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