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Compound flexible packaging heat seal material, related to food safety events!
Nov 25, 2016

Heat sealing layer of composite packaging material: polyethylene film

For composite sealing layer of polyethylene, mainly low density polyethylene and linear low density polyethylene (also some products use medium density and high density polyethylene film heat sealing layer), and generally uses two kinds of blends of polyethylene by a certain percentage for later use. According to different processing methods, can be classified as blown film, cast film extrusion coating and thin film. Polyethylene film for compound, thickness, according to the requirements of the packaging, and choose a different thickness, thin at about 20 μ thick can be greater than 100 μ. Because there are many additives in the production of resins for film, especially slip additive, pay attention to the migration of additives in the production.

MPE can be said to be a revolution of the polyethylene resin, made with metallocene Polyethylene films, has good thermal adhesive strength, heat seal strength, there is a certain resistance to seal contamination. Currently metallocene catalyzed PE and LDPE blends the production of films, has oil, shampoo, detergent and so widely used. Composite packaging heat seal layer great part made of polyethylene, such as instant noodles, biscuits, preserved vegetables, pickles, etc. Blown film and cast film processing Central through EDM process, so that surface tension is greater than 38 Dyne/cm.

Heat sealing layer of composite packaging materials II: polypropylene film

Polypropylene films can also be divided into blown film (blown under law), cast film extrusion coating and thin film. Polypropylene film, cast polypropylene films (CPP films) is one of the most used, it is mainly used in high temperature cooking of packaging, packaging with high transparency requirements, CPP with CPP films made of aluminum-plated aluminum (VmCPP), used in food packaging, instant noodle packaging.

High temperature cooking of CPP and CPP for aluminum materials and common CPP's raw materials are different, with special requirements, high temperature cooking in addition to copolymerization of colonization, with block copolymers and its temperature resistance should be the best and aluminizing CPP materials preferably terpolymer. Some businesses in order to save costs, less demanding products and polypropylene blown film is used as the inner layer is enough. Production film is the electrical discharge of surface treatment, it is best that surface tension is greater than 40 Dynes/cm.

Composite packaging materials heat sealing layer three: sealing film

On the market of jelly, cold drinks, yogurt, milk and other food are mostly made of plastic cups and plastic bottles, cups and bottles it be sealed in a thin film. Some requirements can be opened, and some don't have to reveal. Without open heat sealing layer is generally used in milk packaging such as milk, fruit, Cup or bottle was largely based on high density polyethylene (HDPE) resins as ingredients. Lining materials use and glass (bottle) can be made of the same materials. On one hand you want to have a good seal strength, while opening performance of the other party, for this special requirement, choice of heat sealing layer is very important.

Along with two kinds of modification of functional materials is EVA. EVA-ethylene-vinyl acetate copolymer, polypropylene, polystyrene and it has good adhesion, but it differs from the molecular structure of polypropylene, polystyrene, heat seal bonding time, two kinds of resin cannot be completely diffusion, osmosis, melted together. Bond strength can only be formed with a clear interface. So use EVA as a lidding film modified by heat sealing layer, has enough heat seal strength and easy opening of peeling.