Properties and standards of polypropylene cast film

日期:2019/6/14 8:19:30 / 阅读: / 来源:本站

Properties and standards of polypropylene cast film
1) Transparency, normal relative molecular mass polypropylene has excellent transparency, and its optical properties are almost the same as those of cellophane, polyvinyl chloride and polystyrene. Casting on the chill roll, the haze can reach less than 4%, so it can enter the food and textile packaging market with high transparency requirements.
There are 2) tensile strength, and the tensile strength of the polypropylene cast film is twice that of polyethylene, and is usually 35 to 50 Pa. The size is determined by the production conditions and the direction of measurement. In the production process, the orientation of polypropylene is much stronger than that of polyethylene, especially at high speeds. But it is directional, and the vertical is better than the horizontal. Straight out
3) Tear strength, the tear resistance of polypropylene cast film is not very good, in general, the longitudinal direction is higher, the lateral direction is lower, and it can withstand the general perforation, but it is not suitable for heavy packaging articles.
4) Toughness, the polypropylene film has good toughness and its toughness is 3 to 4 times that of polyethylene, so in many applications, the thickness can be reduced, thereby reducing the cost. The absolute value of the toughness is proportional to the cube of the thickness of the substrate. The toughness of polypropylene is at least three times that of polyethylene. Therefore, a polypropylene film is generally used, and the thickness is generally about 60% of the thickness of the polyethylene.
5) Impact strength, the effect of polypropylene cast film orientation makes the impact strength different, so it is difficult to enter the heavy packaging market, and is applied to light packaging such as textiles and food packaging.
6) Temperature resistance, isotactic polypropylene has a high melting point of 168 ~ 170 ° C, can withstand steam sterilization, used as packaging medical equipment and cooking food bags, and its solvent corrosion resistance is better than polyethylene, and has resistance The temperature is therefore suitable for the substrate of the composite film. In addition, the temperature is low, the temperature for maintaining the strength is high, and the practical advantage is higher than that of the high-density polyethylene and the low-density polyethylene, and the low-temperature performance is poor. Block copolymers have better low temperature properties.
7) Heat sealing performance, polypropylene cast film has a wide heat sealing temperature range, plus good toughness, suitable for mechanized packaging.
8) Gas barrier property, CPP has a moisture permeability coefficient lower than that of LDPE and cellophane, slightly higher than BOPP, and is a moisture-proof material, and the oxygen permeability coefficient is lower than CPE and BOPS, and higher than HDPE, BOP, BOPET, PVDC.


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