In recent years, transparent PP has developed rapidly. In 2013, the domestic consumption reached 700000 tons, accounting for about 4% of the total PP. In 2016, the total apparent consumption of PP in China has reached 21 million tons, of which the consumption of transparent PP has also increased to 1.2 million tons, becoming one of the fastest-growing PP products.
In the United States, almost all ordinary PP manufacturers are producing transparent PP resin, and the development speed of transparent PP products is 7% – 9% higher than that of ordinary PP products. In Japan, the annual output of transparent PP is more than 1000K tons, accounting for 9% of the total consumption of PP products, and the market consumption continues to grow. Why is transparent PP so popular in the market?
1. Introduction to transparent PP / polypropylene:
Polypropylene (PP) has excellent characteristics such as good mechanical properties, non-toxic, low relative density, heat resistance, chemical resistance, easy processing and molding, and high performance price ratio. It has become the fastest growing and most active variety in new product development among the five general synthetic resins. However, because PP belongs to partial crystalline resin, under normal processing conditions, the crystallization speed is relatively slow and it is easy to form large spherulites. The easy crystallinity of PP makes the luster and transparency of its products worse and the appearance lacks aesthetic feeling, which limits its application. Therefore, in the past two decades, many western countries have successively carried out the research and development of high transparent polypropylene materials and commercialized them one after another.
After transparent modification of PP, the spherulite structure is uniformly refined, and the transparency and gloss are significantly improved. It not only inherits the advantages of ordinary PP, but also effectively improves its crystallization temperature, Vicat softening point, rigidity and other mechanical properties, and can even be comparable to other transparent resins such as PS, pet, PVC, PC, etc. The performance price ratio is better than that of pet, PVC, PS and PC. therefore, it has developed rapidly in the world since it came out in the early 1980s and has been widely used in many fields such as transparent packaging, medical appliances, daily necessities and so on.
Transparent PP shows many excellent properties in chemical stability and toughness (see the table below).
2. Application fields of transparent PP / polypropylene:
Transparent PP materials are mainly used in injection molding, hollow molding, thermal molding, injection pull blow molding and other fields. In terms of application, transparent PP material has been widely used in daily necessities, microwave ovens, cookers and other household products; Packaging products, syringes and other medical equipment are the related applications of transparent PP materials in the pharmaceutical field, which has a very large development space. In addition, thin-walled injection products are the application trend of transparent PP materials at this stage. This product not only has strict requirements for the standard of making molds, but also needs very good flow performance of raw resin. Therefore, this field will develop into a new growth point for the application of transparent PP materials. The specific application scope is shown in the table below.
3. Production status of transparent PP / Polypropylene Abroad:
The main manufacturers and product brands of transparent PP abroad are shown in the table below.
BP Amoco cooperated with American merican company to launch acclear series transparent PP resin with millad3988 transparent nucleating agent. Among them, the melt flow rate (MFR) of 8649x transparent PP is 23g / 10min, and its transparency is close to that of transparent PET resin. It can be used in the production of injection pull blow molding PP bottles; The brand 8940x transparent PP is a high fluidity resin with an MFR of 55g / 10min. It can be used for high-speed injection molding to produce optical disc boxes, tape boxes, food containers and other hard packaging materials. This series is one of the transparent PP products with the best transparent performance and the earliest commercialization. Montel also launched transparent PP resin products. One of them, pro faxsr832m, has high transparency and good impact resistance. It has been used in the production of packaging materials for audio-visual products and household utensils.
Huntsman developed a new random copolymerized transparent PP resin using the 4th generation Z-N catalyst and rexene’s patented technology. Among them, the MFR of brands rexene23m2a, 23m2acs038 and 23m2acs198 are 2G / 10min, which are special resins for injection molding, extrusion and stretch blow molding; The MFR of rexene13m11a is 11g / 10min, which can be used to produce electronic products and drug packaging materials. The heat resistance, rigidity and stability of the above products have been improved, and can be sterilized under high pressure. More domestic imports mainly include transparent PP produced by Korean Dalin and Korean SK company. Rp344r of Dalin, Korea has good transparency and gloss. It can be used in the field of food and medicine and is suitable for the processing and molding of thin-walled products. R370y developed by SK company in Korea has excellent transparency and good fluidity, and can be used for the molding and processing of food packaging containers and large thin-walled transparent products.
Dow Chemical Co., Ltd. and merican Co., Ltd. launched a new generation of PP product series – agilitnx transparent PP resin, which has excellent appearance, improved service efficiency and greatly improved the processability of PP. The resin adopts milliadnx8000, a new generation of transparent nucleating agent of merican, and Dow Corning random copolymerization PP production technology. The transparent PP can be used for injection molding to produce thin-walled food and consumer goods storage containers and other consumer goods with high cleanliness requirements.
Some large foreign companies are also actively developing metallocene transparent PP products, and Basell is in a leading position in this regard. The metallocene series transparent PP products launched by the company not only have the characteristics of high transparency, high rigidity, high fluidity, high gloss, easy processing and narrow relative molecular weight distribution, but also can resist environmental stress cracking and chemical corrosion. They have been widely used in the fields of fiber and injection molding ExxonMobil also launched metallocene homopolymer transparent PP (achievexpp-68), which has outstanding transparency, rigidity and fluidity, and can be widely used in food packaging, thin-wall injection molding and other fields.
4. Production status of transparent PP / polypropylene in China:
China began to research and develop transparent PP resin in the 1990s, which started relatively late compared with foreign countries. The following table shows the common brands of transparent PP special materials in China. However, there is still a large gap between China and foreign companies in the types and market consumption of transparent PP products and the research and development of related process technology.
Yanshan Petrochemical Company of Sinopec (hereinafter referred to as Yanshan Petrochemical) developed transparent PP products by adding transparent nucleating agent in the early stage. There are k4808, k4818, k4902 and other brands, which can be mainly used in thermoforming, injection molding and other fields. In addition, there are two special materials b4902 and b4808, which are used to make PP infusion bottles. They have the comprehensive properties of high bottle forming rate and excellent processing performance. At present, there are 492 grades of transparent propylene, K25 grades of transparent propylene and K25 grades of non nucleated propylene, which can be used in the production process of transparent propylene, and K25 grades of non nucleated propylene. At the same time, the flow performance of non nucleated propylene can reach the level of transparent propylene and stable ethylene, respectively.
The main brands of transparent PP in the early stage of Sinopec Shanghai Petrochemical Co., Ltd. (hereinafter referred to as Shanghai Petrochemical) are m250t, M250E, m450e, m800e, m1200e and m3000e; Later, the company successfully developed new products m850b and m1200b of propylene / butene random copolymerization transparent PP series. The test and evaluation results show that not only the content of n-hexane in the product is very low, but also the balance of transparency, toughness and rigidity of the product is realized. In addition, the hygienic and safety grade of the transparent PP resin has also been improved, so it has obvious advantages in the field of medical supplies and food contact packaging.
Qilu Petrochemical Company of Sinopec (hereinafter referred to as Qilu Petrochemical) has developed two new transparent PP resins qpt91n and qpt93n by using milladnx8000, the latest generation of transparent nucleating agent of merican. Both products have excellent aesthetics, transparency, processing stability and excellent quality. Among them, the MFR of qpt91n is 30g / 10min, which is the first high melt flow rate transparent PP commercialized by hydrogen modulation in the domestic market, and no peroxide is added in the production process. Therefore, compared with the products using peroxide, the yellow index and odor are much lower, which can be applied to large food containers, storage containers and other fields.
Lanzhou Petrochemical Company has also developed the special material rp340r for random copolymerization transparent PP, and has successfully carried out industrial production on its 110kg / a PP unit. The new product can be processed in a wide temperature range without yellowing, poor gloss, odor and other problems. It can replace PS and be applied to thermoformed PP food packaging containers. The melt flow rate, bending modulus and impact strength of the product are better than those of similar products.
Sinopec Maoming Branch and Sinopec Beijing Research Institute of chemical industry have developed a special material ppbmt25-s for high impact and low temperature resistant transparent pp. this product has both high transparency and low temperature impact resistance, which makes up for the lack of impact resistance of general transparent PP under low temperature conditions. Therefore, it can be widely used in the production of low temperature food packaging, low temperature resistant fresh-keeping box and other transparent plastic products
On the whole, limited to the process production technology of PP and transparent nucleating agent, there is still a large gap between domestic transparent PP products and foreign products in terms of gloss, transparency and mechanical properties. Therefore, domestic transparent PP products are mainly medium and low-grade transparent PP products, while high-grade transparent PP products mainly rely on foreign imports. At present, most of them are transparent PP special resin produced in Korea.
5. Summary:
With its high transparency, low production cost, superior material properties and wide application fields, the production demand of transparent PP is rising. However, due to the weak production and R & D technology of domestic manufacturers, relatively backward processing conditions, and the start of domestic transparent agent is far behind that of foreign countries, the stability of the effect of its nucleating agent modified products and the dispersion of nucleating agent lag behind that of imported products. Therefore, in the field of high-end products, we can only rely on imports to make up for market demand. At present, transparent nucleating agent modified PP is mainly used in domestic transparent PP production, and high-performance transparent agent has been monopolized by foreign giant companies. Therefore, considering the domestic market demand, it is of great practical significance to develop and produce a series of efficient, multifunctional and low-cost transparent nucleating agents; In addition, the market prospect of random copolymerized transparent PP resin is very good, but most products still rely on imports. Therefore, we should seize the opportunity and speed up the research and development of random copolymerized transparent PP products.
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