Low-shrinkage rate bidirectional stretching plastic thin film and preparation method thereof

Abstract

The invention discloses a low-shrinkage rate bidirectional stretching plastic thin film which comprises a core layer and also comprises an upper surface layer and a lower surface layer, wherein the upper surface layer and the lower surface layer are made of the following materials in parts by weight: 60 parts of polyethylene glycol terephthalate with the SiO2 content of 3,000 ppm and 40 parts of polyethylene glycol terephthalate. The preparation method for the low-shrinkage rate bidirectional stretching plastic thin film comprises the following steps of A. coextruding an upper surface layer material, a core layer material and a lower surface layer material after material mixing is executed; B. longitudinally stretching; C. transversely stretching, and cutting off two longitudinal edges of the film before the film is completely cooled; D. performing corona treatment on the film from a widening machine in a dragger, and winding the film from the dragger in a winding machine. The two longitudinal edges of the film are cut off before the film is completely cooled, so that the film can be shrunk to a certain extent in the longitudinal direction, and the longitudinal shrinkage rate can be reduced; furthermore, the film can be shrunk to a certain extent in the transverse direction during the longitudinal shrinkage of the film, and therefore, according to the method, the transverse shrinkage rate of the film can be controlled at the same time.

Description

(1) Technical field [0001] The invention relates to a biaxially stretched plastic film and a preparation method of the film. (2) Background technology [0002] The share of plastic film products in the market is increasing, especially composite plastic flexible packaging, which has been widely used in food, medicine, chemical industry and other fields, among which food packaging accounts for the largest proportion, such as beverage packaging, quick-frozen food Packaging, cooking food packaging, fast food packaging, etc. These products have brought great convenience to people's lives. In addition, plastic films are also more and more widely used in various fields of industry, such as lithium battery separators, solar back Films for boards, films for liquid crystal displays, etc. [0003] However, currently the most widely used biaxial stretching technology is to use the following process: raw material mixing - drying - extrusion - casting - longitudinal stretching - horizont...

AI Technical Summary

Problems solved by technology

However, there are two problems in this method: one is that the transverse width of the plastic film is affected to a certain extent during baking, which may cause insufficient width of the product and thus be scrapped; second, the use of secondary baking increases production costs and reduces production efficiency , less economical

Images