Plastic bucket manufacturer ——Plastic products are the general name of living, industrial and other products processed with plastic as the main raw material. Including plastic injection molding, blistering and other products with all processes.
Xi'an plastic bucket manufacturer Plastic is a kind of plastic synthetic polymer material. Together with synthetic rubber and synthetic fiber, it forms three indispensable synthetic materials in daily life. Specifically, plastic is a material that takes natural or synthetic resin as the main component, adds various additives, forms a certain shape under a certain temperature and pressure, and maintains its shape at room temperature.
1. Pretreatment of plastic coating
Pretreatment includes degreasing treatment on the surface of plastic products, that is, removing the oil stain and release agent on the surface of plastic products, and activating the surface of plastic products to improve the adhesion of the coating.
(1) Degreasing of plastic products. Similar to the surface degreasing of metal products, the degreasing of plastic products can be cleaned with organic solvent or alkaline aqueous solution containing surfactant. Organic solvent degreasing is suitable for cleaning paraffin, beeswax, grease and other organic dirt on the surface of plastic products. The organic solvent used shall be insoluble, non swelling and non cracking plastic products. Low boiling point, volatile, non-toxic and nonflammable.
Alkaline aqueous solution is suitable for degreasing of alkali resistant plastic products. Because the solution contains caustic soda, alkaline salt and various surface active substances. The commonly used surfactant is OP series, namely alkyl phenol polyoxyethylene ether, which will not form foam or remain on the surface of plastic products.
(2) Activation of the surface of plastic products. Activation is to improve the surface energy of plastic products. It is to generate some polar groups on the surface of plastic products or coarsen them, so that the coating can be more easily wetted and adsorbed on the surface of parts. The surface activation treatment methods of plastic products include chemical oxidation, flame oxidation, solvent vapor corrosion and corona discharge oxidation. Among them, chemical crystal oxidation method is widely used. Chromic acid treatment solution is usually used for this method. Its typical formula is potassium dichromate 4.5%, water 8.0%, concentrated sulfuric acid (more than 96%) 87.5%.
Some plastic products of plastic bucket manufacturers, such as polystyrene plastic products and ABS plastic products, can also be directly coated on the surface of plastic products without chemical oxidation treatment. In order to obtain high-quality coatings, chemical oxidation treatment is also used, such as ABS plastic products. After degreasing, dilute chromic acid treatment solution can be used for etching. The typical treatment formula is chromic acid 420g/L, sulfuric acid (specific gravity 1.83) 200ml/L. The typical treatment process is 65 ℃, 70 ℃/5min, 10min, water washing, drying.
The advantage of etching with chromic acid treatment solution is that no matter how complex the shape of plastic products is, they can be uniformly treated, but there are certain dangers and pollution problems in the operation.
2. Coating pretreatment
The purpose of coating pretreatment is to improve the adhesion between the coating and the surface of plastic products, and form a conductive metal bottom layer on the surface of plastic products. Pretreatment processes mainly include: mechanical roughening, chemical degreasing, chemical roughening, sensitization, activation, reduction and electroless plating. The first three items are used to improve the adhesion of the coating, and the last four items are used to form a conductive metal substrate.
(1) Mechanical and chemical roughening. Mechanical roughening and chemical roughening use mechanical and chemical methods to roughen the surface of plastic products respectively to increase the contact area between the coating and the substrate. It is generally believed that the binding force of mechanical roughening is only about 10% of that of chemical roughening.
(2) Chemical degreasing. The degreasing method for surface coating pretreatment of plastic products is the same as that for coating pretreatment.
(3) Sensitization. Sensitization has a certain adsorption capacity. Some easily oxidized substances, such as tin dichloride and titanium trichloride, are adsorbed on the surface of plastic products. These easily adsorbed and oxidized substances are oxidized during the activation process, and the activator is reduced to the catalytic crystal nucleus and left on the surface of the plastic products.
(4) Activate. Activation is the surface treatment of sensitized plastic products by using metal compound solution with catalytic activity. Essentially, plastic products with reductant adsorbed are immersed in oxidant aqueous solution containing precious metal salts, so their precipitation is very good
