PVC plastic, chemical field refers to the compound polyvinyl chloride. English name polyvinyl chlorid, abbreviation PVC. this is the most widely used meaning of PVC.
It is a yellowish translucent color, shiny. Transparency better than polyethylene, polypropylene, worse than polystyrene, with different amounts of additives, divided into soft and hard PVC, soft products are soft and tough, sticky feel, hard products, the hardness is higher than the low-density polyethylene, but lower than the polypropylene, in the bending place will be whitening phenomenon. Common products: plates, pipes, shoe soles, toys, doors and windows, wire outer skin, stationery, etc.. It is a polymer material that uses a chlorine atom to replace a hydrogen atom in polyethylene.
PVC plastic itself is non-toxic, but the vinyl chloride (VCM) monomer used to polymerize PVC is carcinogenic. It is usually stipulated that VCM content below 1PPM is non-toxic sanitary grade resin. So to see whether PVC is toxic first is to see whether the resin is sanitary resin. Second, look at the additives, PVC processing to use a large number of additives, additives have toxic and non-toxic, especially stabilizers, opaque with lead salts, cadmium salts, barium salts, etc. is poisonous, other non-toxic. Other ribbing agents are the same, there are toxic and non-toxic. So, PVC is non-toxic, but whether PVC products are toxic, depending on the specific products, not necessarily, like PVC sheets used in large quantities in pharmaceutical packaging, disposable infusion tubes are all PVC. PVC's thermal stability is not too good, easy to decompose by heat, but the temperature at least in the 170 degrees or so, and the light will not cause the decomposition of PVC, the construction of the current drainage pipes are all PVC, so it is very unstable and extremely non-toxic, so it is very unstable and extremely non-toxic. So it is very unstable and extremely inaccurate. Decomposition is the production of HCL, the odor is very pungent, generally only the production process, the use is not going to appear, this everyone can rest assured. So it is recommended that you direct contact, or do not buy pvc materials, such as cups, spoons, such as the recommendation that you still buy ceramic or iron is safer.
PVC material characteristics and performance:
PVC (polyvinyl chloride) chemical and physical properties Rigid PVC is one of the most widely used plastic materials. pvc material is a kind of non-crystalline materials. Stabilizers, lubricants, auxiliary processing agents, colorants, reinforcing agents and other additives are often added to PVC materials in actual use.
PVC material has non-flammable, high strength, weather resistance and excellent geometric stability. PVC is highly resistant to oxidizing agents, reducing agents and strong acids. However, it can be corroded by concentrated oxidizing acids such as concentrated sulfuric acid and concentrated nitric acid, and is also not suitable for contact with aromatic hydrocarbons and chlorinated hydrocarbons.
The melting temperature of PVC is a very important process parameter during processing, and if this parameter is not correct, it will lead to problems of material decomposition. The flow characteristics of PVC are quite poor and its process range is very narrow. Especially large molecular weight PVC material is more difficult to process (this material usually need to add lubricants to improve the flow characteristics), so usually use small molecular weight PVC material. The shrinkage of PVC is quite low, typically 0.2 to 0.6%.
Injection Molding Process Conditions
Melting Temperature: 185~205℃ Mold Temperature: 20~50℃
Injection Pressure: up to 1500bar Holding Pressure: up to 1000bar Injection Speed: To avoid material degradation, injection speeds are generally quite high.
Runners and gates: All conventional gates can be used. For smaller parts, it is best to use a pin-tip or dive-in gate; for thicker parts, it is best to use a fan gate. The minimum diameter of a pin-tip or submerged gate should be 1mm; a fan gate should not be less than 1mm thick.
Typical applications Water supply lines, domestic plumbing, house wall panels, commercial machine housings, electronics packaging, medical equipment, food packaging, etc.
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