Polypropylene is the category with the largest amount of individual bai in all plastics, and it is also the category with the widest application range. It can be classified according to different substrates, and the specifications can still be determined with different melt flow rates within the classification. Add additional additives according to individual products, and then define the use specifications. For example, in a single polymer, MFR: about 12 can be used for general injection products, and can also be used to produce multifilament fibers. It can also be specially made to improve fiber weaving with a wide molecular weight distribution. The post-processability; at the same time, slip agents and anti-adhesive agents can be added to increase the opening to facilitate the requirements of the finished plastic bag. Therefore, many specifications have been extended, but the general physical properties are similar, and they are mutually replaceable in addition to non-intended main uses. Here try to classify the different substrates for reference and explain them one by one.
1. HOMOPOLYMER single polymer, called homopolymer in mainland China, is a raw material made by polymerization of pure propylene.
2. Impact resistance (IMPACT COPOLYMER) is a single polymer with ethylene propylene rubber added. The impact strength mainly depends on the rubber content, and the cold resistance mainly depends on the ethylene content. The process of each raw material manufacturer is different, and the maximum ethylene content is also different.
3. RANDOM COPOLYMER is a random copolymer, which is copolymerized with propylene and ethylene. The ethylene is irregularly dispersed in the polymer, which mainly reduces the crystallinity of the polymer and improves the transparency.
4. HIGH ISOTACTICITY or HIGH CRYSTALLINITY reduces the content of dislocation structure in PP polymer, relatively increases the content of regular structure, and also increases the crystallinity. Mainly improve the rigidity, heat denaturation temperature, surface hardness, scratch resistance and gloss of raw materials. Of course, adding nucleating agent will also help the improvement of the above physical properties
5. TERPOLYMER is an extension of random copolymers. Generally, propylene contains ethylene (non-EPR) content up to 3.5%, but there are also processes that can be added to 5%. The higher the ethylene content, the softer the product, and the thermal deformation temperature , The lower the softening point and the heat-sealing temperature, sometimes in order to increase the ethylene content, butadiene or other third components are used to form a terpolymer to meet the above physical properties.
6. Alloy grade (ALLOY) The high proportion of different plastic raw materials can be described as alloy grade. For example, the addition of LDPE to PP can improve flexibility and impact strength. It can also reduce necking and increase flatness in processing. It can also be reduced in molding. Falling material phenomenon. PP plus EPR plus HDPE can maintain rigidity, reduce whitening caused by high EPR content, and improve impact strength.
