Thermoplastic acrylic resin does not undergo further crosslinking during the film formation process, which means it has a relatively high molecular weight, good water and chemical resistance, good gloss and color retention, fast drying, convenient construction, and easy application for recoating and rework. In addition, the Aluminum powder has good whiteness and positioning in the process of Aluminium powder preparation. Thermoplastic acrylic resins are widely used in fields including those of electrical appliances, automobiles, machinery and construction.
The thermosetting acrylic resin refers to a network structure formed when a certain functional group in the structure reacts with the functional groups in the epoxy resin, amino resin and polyurethane, which are added during the preparation of the paint. The thermosetting resin usually has a relatively low molecular weight. Thermosetting acrylic coatings have excellent gloss, fullness, hardness, solvent resistance, weather resistance, and no discoloration and yellowing when baked at high temperatures. It can be formulated with amino resin to prepare amino-acrylic baking paint. Presently, it is widely used in products including motorcycles, automobiles, bicycles and coiled steel products.
Acrylic resins can be classified according to their production modes:
1. Emulsion polymerization is formed by the reaction and polymerization of monomers, initiators and distilled water. Generally, the resin is an emulsion with a 50% of solid content, a latex solution containing about 50% of water. The synthesized emulsions are generally milky white with bluish tints (Tyndall phenomenon), and the glass transition temperature is designed according to the FOX formula. Therefore, this type of emulsion has large molecular weight, but the solid content of it is usually 40% to 50%. The production industry requires precise control because of the use of water as a solvent and environmentally- friendly emulsion.
2. Suspension Polymerization. It is a relatively complicated production process which is used as a method for producing solid resins. The solid acrylic resin is reacted and polymerized with Methyl propiolate. Methyl propiolates, generally carrying certain functional groups, are not easy to control during the polymerization reaction in the reactor, but is easy to become sticky resulting to the explosion of the pot. The procedure is to put monomers, initiators and additives into the reactor and then add distilled water into it to react. After reacting at certain temperature for a certain period of time, wash it with water, dried it and then filtered it, etc. The production control of the product is relatively strict. Once a certain link is not in place, the product that comes out of it will be affected to a certain extent, which mainly reflects in the color and the molecular weight.
3. Bulk polymerization. It is a relatively efficient production process, which is to put raw materials into a special plastic film, letting it react into agglomerate, and then take it out to pulverize it and filter it. The purity of the solid acrylic resin produced by this method is the highest among that out of all production methods, and the product is the most stable. For all this, the disadvantages, however, can not be neglected. Acrylic resins formed by bulk polymerization do not have strong solubility in solvents. Sometimes, products formed by bulk polymerization are several times harder to dissolve than those formed by suspension Polymerization, even with the same monomer and the same match, and its dispersiveness of pigments is not as good as that of suspension polymerization.
4. Other polymerization method-solvent reaction. During the reaction, put it into the reactor as a intermediate substance, react, and then remove solvent residue.