Nylon resin is treated with special chemical methods to weaken the shortcomings such as hydrolysis and oxidation, and strengthen the heat resistance. From these requirements, we have to choose the appropriate plastics from various plastics, and the properties of our PA66 engineering plastics just meet these requirements. When our customers ask to choose a suitable material for their products, we also have to first see what requirements the products have. The mold temperature also has a great impact on the crystallization performance of PP. the mold temperature is high, the crystallinity is high, the rigidity is large, but the shrinkage rate is large. On the contrary, the mold temperature is low, the product crystallinity is low, the toughness is good, and the shrinkage rate is reduced. Therefore, the temperature is generally controlled at 40 ~ 80 ℃ and cooled with water.

It is necessary to desliminate and remove random substances in vertical stirred tank reactor. Due to different solvents, operation conditions and process steps are different. Although the slurry process was very popular at that time, the proportion of traditional slurry process in production has declined obviously in recent years. From the plastics that meet the requirements, we can choose the most suitable plastic raw materials from the aspects of property ratio, cost and quality. For the material selection of valve cover, we often identify PA66, which is not of poor quality, PMMA is a general-purpose plastic with low price and wide application. The most common one should be transparent PMMA, and Transparent PMMA products often encounter different problems in the processing process.

Today, we will focus on the analysis of these possible problems. 1. Plastic lenses: spectacle lenses include shortsighted lenses, presbyopia lenses and sunglasses. Using injection molding method, a certain degree of glasses can be formed at one time, which is easy to dye and low cost. Generally, PMMA materials are used, and fiber, transparent nylon or PC plastic are used for high requirements. Generally, cj150m3 and cj180m3 machines are used to process spectacle lenses, and small screws are selected. The mold cavity is generally designed to be 1 × 5 or 1 × 6 circular symmetrical arrangement. The size of presbyopia lenses and short-sighted lenses requires a long holding time to reduce shrinkage, so that the products can reach the designed size. Sunglasses belong to flat lenses, and the requirements are not so high, but they are generally dyed, including one-step dyeing and two-step dyeing. 2. Craft decoration ball (￠ 40 or so): the equipment is generally 80t or 120t to ensure sufficient injection pressure. The material is PMMA plastic (much easier to process if the material is GPPS). The die is usually designed to be 1 × 1 or 1 × 2. Two plate dies with hot nozzle or large water mouth can be used. Because the thickness of the products is very large, it is difficult to control the shrinkage, internal bubbles and surface impurities.