What is the difference between cast nylon wheels and ordinary nylon wheels?


1. Different ways of polymerization
Ordinary nylon wheels are melted caprolactam monomers subjected to hydrolysis and ring-opening polymerization in the presence of acidic catalysts. The reaction requires high pressure (autoclave or polymerization tube), high temperature (250°C) and long time (10-20 hours or more), polymerization equipment It is more complicated and has many procedures. The cast nylon wheel is an anionic ring-opening polymerization of molten caprolactam monomer in the presence of an alkaline medium. At normal pressure and a temperature of about 170°C, it only takes a few minutes to reverse the quotient.
2. Differences in polymer properties
Generally, the molecular buds of nylon wheel polymers are generally below 30,000, and the crystallinity does not exceed 40%; while the molecular weight of cast nylon is about 7 to 100,000, the crystallinity can exceed 50%, and the density is also large. In terms of strength, stiffness, wear resistance and chemical resistance, cast nylon is much superior to ordinary nylon 6. It also has less water absorption and better dimensional stability than ordinary nylon 6.
3. The molding method of the product is different
Ordinary nylon wheel polymers need to be cast, granulated, extracted and dried before they can be processed. The molding method is usually an injection method. The injection molding machine equipment must bear a lot of orbital force; the mold is complicated, the processing accuracy is very high, and the production cost is large. Moulded nylon is the molten monomer together with the basic catalyst and other additives, directly poured into the mold under normal pressure for molding, polymerization and product molding are carried out in a mold at the same time, the process is short, the casting equipment is simple, Low mold cost.
4. The size of the molded product is not limited
Ordinary nylon wheel products are obtained by injection molding. The size of the products is limited by injection molding machines and molds. It is very difficult to form products of more than 2 kilograms, so it is generally based on small parts. In theory, as long as the mold allows, the size of the molded nylon products is not limited and there is no directionality.