Talking about the surface coating treatment of plastic products

Plastic coatings are available in a wide variety of plastic products with varying performances. In recent years, the widely used plastics in China are PVC (polyvinyl chloride), ABS (modified polystyrene), PE (polyethylene), PP (polypropylene), PS (polystyrene), HIPS (high impact resistance). Polystyrene), PC (polycarbonate), unsaturated polyester (glass reinforced plastic), and plexiglass.

Coatings used for plastic surfaces must have two basic conditions: 1 the coating must have good adhesion to the plastic substrate; 2 the coating should not excessively dissolve the plastic surface. A variety of different plastics have different structures and properties, and the choice of coatings varies. ABS and PVC plastics have higher polarity and strong affinity with various coatings. There are many varieties of coatings, such as thermoplastic acrylic paint, alkyd modified acrylic paint, polyurethane paint, nitrocellulose paint and vinyl paint. Wait. For non-polar plastics such as PP and PE, a resin matrix with similar structure should be selected, so that an intermixed layer can be formed on the interface to promote intertwining of the segments to improve the adhesion strength. Some plastics have large internal stresses during the molding process, while plastics (such as PS, PC, etc.) have poor solvent resistance. When choosing a coating, the solvent solubility parameter and hydrogen bond value must be considered. Under the premise of not affecting the adhesion of the coating, the difference between the solubility parameter of the solvent base solvent and the solubility parameter of the plastic is as large as possible, so as not to excessively dissolve the plastic surface.

Solubility parameters of common plastic profiles, resins and solvents, solubility parameters of various plastics, plastic names, solubility parameters of various resins of polypropylene, polyethylene, polystyrene, polyvinyl chloride plexiglass, commonly used resin solubility parameters. Solubility parameters of various solvents of nitrocellulose acetate butyric acid vinyl chloride, vinyl acetate resin, acrylic resin, amino resin, short oil alkyd resin, silicone resin, solubility parameter, solubility parameter, toluene, xylene, butyl acetate, The solubility parameters of the resin used in the ethyl acetate, acetone, methyl ethyl ketone ring, ketone butanol, chloroform, diacetate plastic paint should be as close as possible to the solubility parameter value of the plastic, so that the coating film has good adhesion. The solubility parameter of the solvent for the coating differs from the solubility parameter of the plastic as much as possible to ensure that the plastic surface is not dissolved or bitten. At the same time, it is required that the solubility parameter of the resin in the plastic lacquer differs from the solubility parameter value of the plasticizer used in the plastic substrate as much as possible to ensure that the plasticizer does not dialysis. Calculating the solubility parameter is only one, because the same plastic product is different in the manufacturing process and raw material ratio of Hebei Chemical, and its solubility parameter will also have a large gap, so it must be verified by experiments.

The plastic coated plastic itself is a polymer material, and its structure and properties are very different from those of the metal. At the same time, due to defects in the mold itself, the leaching of the auxiliaries in the formulation, and the presence of the release agent on the surface of the mold. And so on, all of which are not considered in metal coating but are the primary issues to be considered in plastic coating.