2018-01-26
PVC wire, namely polyvinyl chloride wire, is one of the largest plastic products in the world. It is cheap and widely used. PVC resin is white or light yellow powder. It can not be used alone, it must be modified. PVC is a white powder with an amorphous structure, with a smaller branching degree and poor stability for light and heat. Different additives can be added to different uses. PVC plastics can show different physical and mechanical properties. A proper amount of plasticizer is added to PVC resin, which can be made into a variety of hard, soft and transparent products.
PVC resin powder each type. The most common in our country is SG-5, and then SG-3, SG-7, SG-8 and so on. What is the difference between different models? In industry, viscosity or K value is usually used to indicate the average molecular weight (or average degree of polymerization) of PVC, that is, the length of PVC molecular chain, to decide and distinguish resin grades and corresponding processing parameters. The molecular weight of the resin is related to the physical and mechanical properties of the products.
PVC resin is a non crystalline linear polymer compound. The larger the molecular weight is, the higher the viscosity number is, the higher the polymer content is, the higher the tensile strength, impact strength and elastic modulus of the product is, but the mobility and plasticity of the melt melt decrease. The molecular weight of the polymer is usually used to represent the molecular weight of the polymer, and the model of the polymer is divided. Let's analyze the features of each model.
The first is the type 3 PVC. Compared with the 5 type, the production of type 3 PVC requires much longer reaction time, higher polymerization temperature, higher requirement for the excipients, and the production cost is higher than that of the 5 type, which is 50-100 yuan / ton. Type 3 PVC is characterized by high purity, less fish eye and easy plastic absorption. It has the characteristics of high temperature resistance, insulation and soft texture. It is mainly used to produce soft products, such as wire and cable, agricultural film, conveyor belt, daily plastic products and so on.
The other is the SG-7/SG-8 and SG-5 type PVC. The three resin production processes are basically the same, and the production equipment is exactly the same. The main differences are the formulation of auxiliary agents, the temperature of polymerization, the pressure of reaction and so on.
PVC has a wide range of applications, and different models are used because of different demand. For example, SG5 (K-65, S1000) is applied to pipes, profiles, plates, etc. SG3 (K-70, S1300) is mostly soft products, and it should be used for manufacturing hoses, wires and cables, films, shoes, toys and auto parts. SG7, SG8 (K-60, S800, S700) are used to make pipes, sheets, containers and so on. In principle, the higher the model, the greater the hardness of the product.
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