Common knowledge of coating: adhesion theory of plastic coating on plastic surface

Core tip: plastic coating can avoid uneven color, monotonous color, speckles and other defects when plastic products are processed, and it is easy to produce aging, embrittlement, scratches, contamination, static electricity and other problems However, because plastic is a low surface energy material, its surface coating is much more difficult than steel, wood, building and other surface coating, adhesion has become a major obstacle to the development of plastic coatings It is necessary to choose different coatings according to different plastic substrates, so as to produce better adhesion The surface free energy of plastic is low and its polarity is small Its surface free energy is less than 10 J / cm Paint agent, top 10 Chinese wall paint brands Recommended introduction: interior wall paint and exterior wall paint can achieve beautiful, clean and pleasant effects, but the effects in different environments are different, so the color of the paint will be different There are ten brands of Chinese paint, ten brands of global paint, ten brands of Chinese wall paint, and ten brands of Chinese paint, Famous trademark of Chinese paint and coating In private rooms, most of us choose according to our own personality, personal hobbies and living habits The younger generation will choose the interior wall paint with rich colors and bright colors, while the older ones will have some working experience Paint Home News: plastic coating can avoid uneven color, monotonous color, speckles and other defects when plastic products are processed, and it is easy to produce aging, embrittlement, scratches, contamination, static electricity and other problems However, because plastic is a low surface energy material, its surface coating is much more difficult than steel, wood, building and other surface coating, adhesion has become a major obstacle to the development of plastic coatings It is necessary to choose different coatings according to different plastic substrates, so as to produce better adhesion The surface free energy of plastic is low and its polarity is small The free energy of the surface is lower than 10 J / cm, so it is difficult to attach the surface Many theories have been put forward on the adhesion of coatings to plastic substrates: diffusion theory, solubility parameter theory, electrostatic theory, chemical bonding theory, adsorption and mechanical engagement theory In fact, all kinds of theories are not contradictory Once the coating penetrates into the plastic substrate, the static electricity and mechanical occlusion between the permeate and the plastic substrate will obviously enhance the adhesion between them In order to make the coating penetrate into the plastic substrate, first of all, it should be able to well wet the substrate, which can be spread on the substrate by mixing the proportion of each component in the coating At this time, the coating and the plastic substrate are combined by chemical force If the solubility parameters of film-forming resin and plastic substrate are selected properly, a mixed layer can be formed between the paint film and plastic surface At this time, the electrostatic and mechanical bite force between the paint and plastic will play a role Although the mixed layer is conducive to adhesion, it depends on the slight dissolution of the solvent in the paint to the plastic If the paint is not properly handled to excessively dissolve the surface of the plastic substrate, the surface of the plastic substrate will be uneven, the paint film will wrinkle, the leveling is not good, and the appearance will be affected Therefore, the solubility parameters of the solvent used should be as far as possible different from the solubility of plastics As both plastics and coatings are complex systems, there are physical and chemical heterogeneity, so there are internal stresses, such as shrinkage stress, thermal stress and deformation stress, which will have adverse effects on the adhesion of coatings, so it is necessary to add appropriate additives and select appropriate coating systems to eliminate them According to the principle of similar structure and polarity, the suitable coating system should be selected for different plastic substrates Home of coatings is specialized in coatings, diatom mud, paint coating, coating technology, fire retardant coating news and coating, diatom mud, paint coating, coating technology, fire retardant coating decoration knowledge and decoration renderings,