Typical applications:
Automotive industry (mainly using PP with metal additives: fenders, vent hoses, fans, etc.), appliances (dishwasher door gaskets, dryer vent hoses, washer frames and lids, refrigerator door gaskets, etc.), consumer products (lawn and garden equipment such as lawn mowers and sprinklers, etc.).
Injection Mold Process Conditions:
Drying Treatment: No drying treatment is required if stored properly.
Melting temperature:220~275℃, be careful not to exceed 275℃.
Mold temperature: 40~80℃, 50℃ is recommended. The degree of crystallization is mainly determined by the mold temperature.
Injection pressure: can be as big as 1800bar.
Injection speed: usually, using high speed injection can minimize the internal pressure. If defects appear on the surface of the product, then low speed injection at higher temperatures should be used.
Runners and Gates: For cold runners, typical runner diameters range from 4 to 7 mm. injection ports and runners with round bodies are recommended. All types of gates can be used. Typical gate diameters range from 1 to 1.5 mm, but gates as small as 0.7 mm can be used. For edge gates, the minimum gate depth should be half the wall thickness; the minimum gate width should be at least twice the wall thickness. PP materials are fully compatible with hot runner systems.
Chemical and physical properties:
PP is a semi-crystalline material. It is harder than PE and has a higher melting point. Because homopolymer-type PP is very brittle at temperatures above 0°C, many commercial PP materials are irregular ****polymers with 1 to 4% ethylene or pincushion-type ****polymers with higher ratios of ethylene content. The *** polymer type of PP material has a lower heat distortion temperature (100°C), low transparency, low gloss, and low rigidity, but has greater impact strength.The strength of PP increases with increasing ethylene content.The Vicat softening temperature of PP is 150°C. This material is more brittle due to its higher crystallinity. Due to its high crystallinity, this material has good surface stiffness and scratch resistance properties.PP does not suffer from environmental stress cracking. Typically, PP is modified by adding glass fibers, metal additives, or thermoplastic rubber.The flow rate MFR of PP ranges from 1 to 40.PP materials with low MFR have better impact characteristics but lower ductile strength. For the same MFR, the *** polymer type is stronger than the homopolymer type. Due to crystallization, the shrinkage of PP is quite high, generally 1.8 to 2.5%. And the directional uniformity of shrinkage is much better than materials such as PE-HD. Adding 30% glass additive can reduce the shrinkage to 0.7%. Both homopolymer-type and *** polymer-type PP materials have excellent resistance to moisture absorption, acid and alkali corrosion, and solubility. However, it has no resistance to aromatic hydrocarbon (e.g. benzene) solvents, chlorinated hydrocarbon (carbon tetrachloride) solvents, etc. PP also does not have oxidation resistance even at high temperatures like PE.
19.PVC (Polyvinyl Chloride)
Typical applications:
Water supply pipes, household pipes, house wall panels, commercial machine housings, electronic product packaging, medical equipment, food packaging, etc..
Injection Molding Process Conditions:
Drying Treatment: Usually no drying treatment is required.
Melting Temperature: 185~205℃
Mold Temperature: 20~50℃
Injection Pressure: up to 1500bar
Pressure Holding Pressure: up to 1000bar
Injection Speed: In order to avoid degradation of the material, it is usually necessary to use a fairly high injection speed.
Runners and gates: All conventional gates can be used. For smaller parts, it is best to use a pin-tip or dive 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; the thickness of a fan gate should not be less than 1mm.
Chemical and Physical Properties:
Rigid PVC is one of the most widely used plastic materials. PVC is a non-crystalline material. it is often used with stabilizers, lubricants, processing aids, colorants, impact agents, and other additives. it is non-flammable, high strength, resistant to weathering, and has excellent geometrical stability. it is resistant to oxidizing agents, reducing agents, and strong acids. However, it can be corroded by concentrated oxidizing acids such as concentrated sulfuric acid, concentrated nitric acid and is not suitable for contact with aromatic hydrocarbons, chlorinated hydrocarbons.The melting temperature of PVC is a very important process parameter when processing, if this parameter is not appropriate, it will lead to the decomposition of the material.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 used are small molecular weight PVC material.PVC shrinkage is quite low, generally 0.2 ~ 0.6%.
17.PPE Polypropylene Ethylene
Typical applications:
Household appliances (dishwashers, washing machines, etc.), electrical equipment such as controller housings, fiber-optic couplings and so on.
Injection molding process conditions:
Drying treatment: 2~4 hours at 100℃ is recommended before processing.
Melting temperature: 240~320℃.
Mold temperature: 60~105℃.
Injection pressure: 600~1500 bar.
Runners and gates: All types of gates can be used. Especially suitable for using shank gate and fan gate.
Chemical and Physical Properties:
Often, commercially available PPE or PPO materials are blended with other thermoplastic materials such as PS, PA, etc. These blends are still called PPE. These blends are still referred to as PPE or PPO.The blended PPE or PPO has much better processing characteristics than the pure material. The variation in properties depends on the ratio of the blends such as PPO to PS. Hybrid materials mixed with PA 66 are more chemically stable at high temperatures. The material has very low hygroscopicity and the products have excellent geometrical stability. The material blended with PS is non-crystalline, while the material blended with PA is crystalline. Shrinkage can be reduced to 0.2% by adding glass fiber additives. This material also has excellent electrical insulation properties and a very low coefficient of thermal expansion. Its viscosity depends on the ratio of the mixture in the material, and an increase in the ratio of PPO will result in an increase in viscosity.