Production technology and performance of dry composite membrane

Since a single plastic film always has the inherent advantages and disadvantages brought by the resin, although from the perspective of synthetic resin, it can be used by physical blending methods, that is, two or more polymers Its own or externally added compatibilizers can be mixed together to produce a new polymer synthetic material with improved certain properties, which can be modified by filling, reinforcement methods, chemical copolymerization methods, and crosslinking methods. But it is still far from meeting the more and more extensive and high performance requirements of packaging for more and more commodities. Therefore, the production of multi-layer plastic film and composite materials such as plastic, paper and metal foil has been developed to learn from each other and better meet the needs of the packaging industry.

Dry lamination is to use an adhesive to coat the substrate, then dry it first, evaporate the solvent, improve the initial adhesion and cohesion of the glue, and then press and laminate it with another substrate. Wet lamination is the opposite. First, glue is applied, pressed and laminated, and then heated, dried and cured. Obviously wet compounding is not suitable for compounding of plastic films. Because after gluing and pressing, a large amount of adhesive solvent is pressed and compounded on the composite film, and the plastic film cannot make these solvents volatilize during drying and curing, nor can it be absorbed by the plastic film, so wet compounding is not suitable for plastics. For lamination between films. Wet compounding is only suitable for the compounding of porous materials, such as paper, wood, plywood, etc. or the lamination of porous foam plastics. Because these materials are loose and have a large number of pores, the solvent in the adhesive can pass through the solids in these materials during the heating and curing process.

The pores give out or are absorbed.

The glue used for wet compounding is generally acrylic latex, EVA latex, phenolic resin glue and other organic solvent glue. The base material is paper, fabric, non-woven fabric, cellophane, aluminum foil, etc. Wet compound glue can also use starch glue. The wet lamination process of aluminum foil and paper is as follows: unwinding of aluminum foil→coating adhesive→pressing with paper→coating slip agent or glazing agent on the other surface of aluminum foil—drying and curing in an oven→winding. The composite material compounded by this method can be used for the packaging of cigarettes, chocolates, etc., and can also be used for the packaging of candy, pharmaceuticals, and baked cakes, but the interlayer adhesion is poor in water resistance, heat resistance, and chemical resistance. Under high temperature and high humidity, these hydrophilic adhesives will have problems such as delamination and corrosion of aluminum foil.