In fact, the PP and PC water cups in the supermarket are both plastic water cups, but what's the difference between them? If they are different, which one will work better? For the difference between PP and PC water cups, let's have a look with Xiaobian.
The difference between PP and PC water cup: PC polycarbonate
Typical applications:
Electrical and commercial equipment (computer components, connectors, etc.), appliances (food processing machines, refrigerator drawers, etc.), transportation industry
(front and rear lights of the vehicle, instrument panel, etc.).
Injection molding process conditions:
Drying treatment: PC material has hygroscopicity, and drying before processing is very important. The recommended drying conditions are 100 ℃ to 200 ℃, 3-4 hours. The humidity before processing must be less than 0.02%.
Melting temperature: 260 ~ 340 ℃.
Mold temperature: 70 ~ 120 ℃.
Injection pressure: use high injection pressure as much as possible.
Injection speed: use low-speed injection for smaller gates and high-speed injection for other types of gates.
Chemical and physical properties:
PC is a kind of amorphous engineering material, which has excellent impact strength, thermal stability, glossiness, bacteriostatic, flame retardant and pollution resistance. The notched Izod impact strength of PC is very high, and the shrinkage is very low, generally 0.1% ~ 0.2%. PC has good mechanical properties, but poor flow characteristics, so the injection process of this material is difficult. When choosing which quality of PC material to use, it should be based on the final expectation of the product. If the plastic parts require high impact resistance, then the PC material with low flow rate can be used; otherwise, the PC material with high flow rate can be used to optimize the injection process.
The difference between PP and PC water cup: PP polypropylene
Typical applications:
Automobile industry (mainly using PP containing metal additives: mudguard, ventilation pipe, fan, etc.), instruments (dishwasher door gasket, dryer ventilation pipe, washing machine frame and cover, refrigerator door gasket, etc.), daily consumer goods (lawn and gardening equipment, such as
Lawn mowers, water sprayers, etc.).
Injection molding process conditions:
Drying: no drying is required if stored properly.
Melting temperature: 220 ~ 275 ℃, pay attention not to exceed 275 ℃.
Mold temperature: 40 ~ 80 ℃, 50 ℃ is recommended. The degree of crystallization is mainly determined by mold temperature.
Injection pressure: up to 1800bar.
Injection speed: in general, the use of high-speed injection can reduce the internal pressure to a minimum. If there are defects on the surface of the product, low speed injection at higher temperature shall be used.
Runner and gate: for cold runner, the typical runner diameter range is 4-7mm. It is recommended to use round injection port and flow channel. All types of gates can be used. A typical gate diameter range is 1-1.5mm, but a gate as small as 0.7mm can also be used. For edge gates, the minimum gate depth shall be half the wall thickness; the minimum gate width shall be at least twice the wall thickness. PP material can use hot runner system completely.
Chemical and physical properties:
PP is a semi crystalline material. It is harder than PE and has a higher melting point. Due to the brittleness of homopolymer PP when the temperature is higher than 0 ℃, many commercial PP materials are irregular copolymers with 1-4% ethylene or clamp copolymers with higher ethylene content. PP materials of copolymer type have lower heat distortion temperature (100 ℃), lower transparency, lower glossiness and lower rigidity, but have stronger impact strength. The strength of PP increased with the increase of ethylene content. The Vicat softening temperature of PP is 150 ℃. Due to its high crystallinity, the material has good surface rigidity and scratch resistance. PP has no environmental stress cracking. Generally, PP is modified by adding glass fiber, metal additive or thermoplastic rubber. The MFR of PP ranged from 1 to 40. PP with low MFR has better impact resistance but lower ductility. For the same MFR material, the strength of copolymer type is higher than that of homopolymer type. Due to crystallization, the shrinkage of PP is quite high, generally 1.8-2.5%. And the direction uniformity of shrinkage is much better than PE-HD and other materials. Adding 30% glass additive can reduce the shrinkage to 0.7%. PP materials of homopolymer type and copolymer type have excellent moisture absorption resistance, acid-base corrosion resistance and solubility resistance. However, it has no resistance to aromatic hydrocarbon (such as benzene) solvent and chlorinated hydrocarbon (carbon tetrachloride) solvent. PP is not as antioxidant as PE at high temperature
Which is the best plastic cup for PC and PP
With the continuous progress of the society, the industry is more and more developed. People are very fond of simple and light plastic cups with high utilization rate, so they often use plastic cups to drink water, but many people have different ideas. Which kind of cup is the safest to drink water? This idea is also very reasonable. After all, plastic cups contain a lot of chemicals. Usually we need to know more about it Some family drinking water knowledge, so that can make this problem solved.
We all know that the safety of plastic cups made of different materials is also different. Which one is better, PC or PP? That's what we all pay attention to. PC cup plastic cup has good light transmittance, lighter than glass and lower price. Generally, it can be heat-resistant to about 100 ℃. It has excellent impact strength, thermal stability, glossiness, bacteriostatic inhibition, flame retardant and pollution resistance. However, it will produce carcinogens such as bisphenol-A after repeated heating. Therefore, countries in Europe, America, Southeast Asia, Japan, South Korea and other countries have issued laws and regulations to prohibit PC materials from being used in infant products.
PP plastic cup is light, not easy to break, good heat resistance, no doubt of toxic substances, stable and safe; the only disadvantage is slightly poor light transmittance. The strength of PP increased with the increase of ethylene content. The Vicat softening temperature of PP is 150 ℃. Due to its high crystallinity, the material has good surface rigidity and scratch resistance. Moreover, the acid-base resistance of PP material is much higher than that of PC. the plastic cup of PP material is also the only plastic box that can be put into the microwave oven, which can be reused after careful cleaning.
After comparing the characteristics of PC plastic cup and PP plastic cup, we can't see that it's better to use PP plastic cup in our life, because the material of PP plastic cup is obviously due to PC plastic cup, and it's also extremely heat-resistant, so it can hardly produce toxic substances. The small safety net of Baibai reminds you that the plastic cup is better made of PP.