A kind of copolymerized polypropylene biaxially stretched film material and its industrial production method

Abstract

The invention discloses a copolymerized polypropylene biaxially stretched film material, the n-hexane extract of which is ≤2%, the melt index is 2.8-3.2g / min, the yellowness index is ≤-2, the haze of the film is ≤1.5%, and the butene bond The total amount is 0.1~1.0%, and its preparation raw materials include polypropylene resin, antioxidant and halogen absorber, wherein, the polypropylene resin is acrylonitrile-butylene random copolymerization polypropylene resin, which is made by the following method: using propylene as The raw material is 1-butene as a comonomer, which is copolymerized in a loop reactor to obtain propylene-butylene random copolymerized polypropylene resin. The reaction temperature is 70±1°C, the reaction pressure is 3.4~3.8MPa, and the hydrogen concentration is 300~1000ppm. The concentration of 1-butene is 0.1%~1%. The invention also discloses the industrial production method of the material. The biaxially oriented film produced by the biaxially oriented film material has good processing properties, optical properties and mechanical properties, and can meet the production requirements of biaxially oriented film packaging manufacturers.

Description

technical field [0001] The invention relates to a copolymerized polypropylene biaxially stretched film material. The invention also relates to a process for the industrial production of the film material. Background technique [0002] Polypropylene biaxially oriented film material (BOPP) is widely used in the field of film packaging materials due to its excellent optical properties, mechanical properties and packaging applicability. Among them, copolymerized polypropylene is widely used in BOPP high-speed production lines because it has better rapid tensile properties than homopolypropylene. [0003] Ordinary binary random copolymerized polypropylene is an ethylene-propylene copolymer of propylene and a small amount of ethylene, but because the reactivity ratio between ethylene and ethylene molecules is higher than that of ethylene and propylene molecules or propylene and propylene molecules, propylene After introducing ethylene into the copolymer segment, the content of s...

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Problems solved by technology

[0003] Ordinary binary random copolymerized polypropylene is an ethylene-propylene copolymer of propylene and a small amount of ethylene, but because the reactivity ratio between ethylene and ethylene molecules is higher than that of ethylene and propylene molecules or propylene and propylene molecules, propylene After ethylene is introduced into the copolymer segment, the content of small molecular polymers will increase significantly. Small molecular polymers are easy to migrate to the surface of the film because of their low molecular weight, and are easy to stick to the roll during production. They always need to be stopped for cleaning, and the production efficiency is very high. Low

Moreover, the low molecular weight part of ethylene-propylene random copolymerized polypropylene often has too high ethylene content, thereby increasing the content of low molecular random substances in the product, resulting in a high n-hexane extract of the product, which limits its application range, especially It is the field of food packaging, because food hygiene certification requires n-hexane extract content ≤ 2%

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