Its natural color is yellowish, translucent and shiny. Transparency is better than polyethylene and polypropylene, but worse than polystyrene. With the different dosage of additives, it can be divided into soft PVC and hard PVC. Soft-packed products are soft and tough and sticky to the touch. The hardness of hard products is higher than that of low density polyethylene, but lower than that of polypropylene, and whitening will occur at the bending point. Common products: plates, pipes, soles, toys, doors and windows, wire sheaths, stationery, etc. It is a polymer material, which uses chlorine atoms to replace hydrogen atoms in polyethylene.
PVC plastic itself is nontoxic, but vinyl chloride (VCM) monomer used to polymerize PVC is carcinogenic. Generally speaking, VCM content below 1PPM is non-toxic sanitary grade resin. Therefore, to see if PVC is toxic, we must first look at whether the resin is a hygienic grade oil. Secondly, look at additives. A lot of additives should be used in PVC processing. Additives are toxic and nontoxic, especially stabilizers. Opaque lead salts, cadmium salts and barium salts are toxic, while others are non-toxic. The same is true of other rib agents, both toxic and non-toxic. So PVC is non-toxic, but whether PVC products are toxic or not depends on the specific products. Not necessarily. For example, PVC tablets are widely used in drug packaging, and disposable infusion tubes are made of PVC. The thermal stability of PVC is not very good, and it is easy to decompose when heated, but the temperature should be at least about 170 degrees, and the light will not cause the decomposition of PVC. At present, the drainage pipes used in buildings are all PVC, so they are unstable and inaccurate. HCL is produced by decomposition, and its smell is very pungent. Generally, it is only found in the production process and will not appear in use. You can rest assured of that. Therefore, it is recommended that you do not buy pvc materials directly. For example, cups and spoons are safer to buy ceramics or iron.
Characteristics and properties of PVC materials;
Chemical and Physical Properties of PVC Rigid PVC is one of the most widely used plastic materials. PVC material is an amorphous material. In practical use, stabilizers, lubricants, processing AIDS, pigments, reinforcing agents and other additives are often added to PVC materials.
PVC material is nonflammable, with high strength, good weather resistance and excellent geometric stability. PVC has strong resistance to oxidants, reductants and strong acids. However, it can be corroded by concentrated oxidizing acids such as concentrated sulfuric acid and concentrated nitric acid, and is not suitable for contact with aromatic hydrocarbons and chlorinated hydrocarbons.
The melting temperature of PVC during processing is a very important technological parameter. If this parameter is not suitable, it will lead to the problem of material decomposition. PVC has poor fluidity and narrow processing range. In particular, PVC materials with large molecular weight are more difficult to process (this material usually needs to add lubricants to improve its flow characteristics), so PVC materials with small molecular weight are usually used. The shrinkage of PVC is quite low, generally 0.2~0.6%.
Technological conditions of injection mold
Melting temperature: 185~205℃ Mold temperature: 20~50℃
Injection pressure: up to 1500bar holding pressure: up to 1000bar injection speed: In order to avoid material degradation, it is generally necessary to use a considerable injection speed.
Runner and gate: All conventional gates can be used. If machining smaller parts, it is best to use needle gate or submerged gate; For thicker parts, it is best to use fan gate. The minimum diameter of needle gate or submerged gate should be1mm; The thickness of the sector gate should not be less than 1 mm.
Typical use water supply pipeline, household pipeline, house wallboard, commercial machine shell, electronic product packaging, medical equipment, food packaging, etc.
Source: network link