Preparation method of double-layer polyester film, and film coated metal plate

Abstract

The invention discloses a preparation method of a double-layer polyester film. The preparation method comprises the following steps: S1, preparation of a modified copolymerized polyester: carrying outa copolymerization reaction on isophthalic acid, 1,4-cyclohexanedimethanol and neopentyl glycol to obtain a modified copolymerized polyester, and adding SiO2 in the copolymerization reaction in an in-situ polymerization mode to obtain a copolymerized polyester resin with 1200 ppm SiO2; S2, preparation of a uniform mixture of the copolymerized polyester and other resins: uniformly mixing the obtained copolymerized polyester and other resins to form a uniform mixture of the copolymerized polyester and other resins; and S3, preparation a double-layer polyester film: forming a polyester film withan upper and lower two-layer structure from the uniform mixture of the copolymerized polyester and other resins by adopting a two-way stretching method and a co-extrusion method. According to the invention, the double-layer polyester film has the advantages of excellent thermal adhesion with a metal plate, excellent deep drawing processing resistance, excellent complex deformation processing resistance, excellent corrosion resistance and the like, and can be widely applied to the metal packaging industry.

Description

technical field [0001] The invention relates to the field of film-coated metal plates for metal packaging, in particular to a preparation method of a double-layer polyester film and a film-coated metal plate. Background technique [0002] In the metal can industry, the traditional method is to paint the surface of the metal plate and then process the can. Among them, the solvent-based coating used in the coating treatment contains non-food safety substances such as bisphenol A, and the coating Due to the volatilization of a large amount of solvents during the installation process, environmental protection problems and a large amount of energy consumption are caused. In recent years, the industry has been committed to finding qualified new materials to overcome the above-mentioned difficulties. [0003] Coated iron is to directly bond the flexible polyester film and the metal plate together by hot melting, which can meet the needs of downstream users for can making and formi...

AI Technical Summary

Problems solved by technology

[0005] The patent application with the publication number CN1839036 discloses a film-coated metal plate and a drawn can used therefor. This patent uses a double-layer film and a thin metal plate to laminate, which is prone to defects such as delamination and falling off during the canning process. The vinyl ionomer used as the intermediate adhesive layer has poor performance when filling and sterilizing at high temperature

[0006] The patent application with the publication number CN102432984 A discloses a cast polyester film and a metal sheet metal can used therefor. This patent uses a single-layer polyester film and a metal sheet to be laminated. As a result, the prepared metal cans have poor performance in acid, alkali, salt and high temperature sterilization during filling.

[0007] The patent with the notification number CN 106142782 B discloses a kind of iron-clad heat-sealing polyester film and its preparation method. Limited to its highly crystalline lower surface, resulting in insufficient processing and forming properties, it is not suitable for deep drawing and complex deformation methods

[0008] The patent application published as CN102463725 A discloses a polyester film and a preparation method thereof. The polyester film of this patent has a three-layer (ABA) structure and is used in the field of electronic tags. It is characterized in that the two surface layers are the same resin, which is very Difficult to meet various performance requirements such as bonding with metal plates, contacting with molds for forming processing, and contacting with the contents of the can, which will easily lead to difficulties in both performance and trade-offs. It is not suitable for the canning industry

[0009] In the existing technology, the single-layer film that meets the deep drawing processing requirements of the coated metal plate lacks high-temperature sterilization performance of acid, alkali and salt resistance in filling, and the multi-layer film that meets the high temperature sterilization requirements of acid and alkali resistance and salt filling cannot meet the deep drawing processing requirements. ;Traditional double-layer film is easy to cause interlayer peeling of the film during deep processing

The traditional film uses silicon-containing chip masterbatches to add anti-blocking agents, resulting in too many types of resins in the film, which are not suitable for deep drawing processing