PVC (polyvinyl chloride) chemical and physical properties. Rigid PVC is one of the most widely used plastic material. PVC material is a kind of non-crystalline materials. PVC material in used actually often add stabilizer, lubricant, auxiliary processing agent, pigment, impact resistant agent and other additives. PVC material have no flammability, high strength, good resistance to climate change and the geometric stability. PVC of oxidant, reductant and strong acid has the very strong resistance. However it can be strong oxidizing acid such as sulfuric acid, nitric acid corrosion and also does not apply to the occasion of contact with the aromatic hydrocarbons, chlorinated hydrocarbons. PVC rigid sheet melting temperature during processing is a very important process parameters, if the parameters will lead to improper material decomposition problem. The flow characteristics of PVC is rather poor, its technological range is very narrow. Especially big molecular weight of PVC material is more difficult to process (this material is usually to add lubricant to improve flow characteristics), so usually use the small molecular weight of PVC material rigid PVC film. PVC shrinkage rate is low, it is generally 0.2 ~ 0.6%.
The process conditions of injection moulds
Dry processing: usually do not need to be dry processing.
Melting temperature: 185 ~ 205 c
Mold temperature: 20 ~ 50 c
Injection pressure: can be reach to 1500 bar
The holding pressure: can be reach to 1000 bar
Injection speed: to avoid material degradation, generally want to use reasonably the injection speed.
Runner and gate: all regular gate can be used. If processing small parts, it would be better to use needle point gate or dive into the gate; For thicker components rigid film, it is better to use the fan gate. Pinpoint gate or dive into the gate of minimum diameter should be 1 mm; The thickness of the fan gate cannot be less than 1 mm.
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