Why is the transparency of PVC plastic bags high?

If some plasticizers, stabilizers and other chemical additives are added to polyvinyl chloride (PVC) resin, PVC cosmetic packaging bags are made by calendering.

Its characteristics are:

1. Good light transmittance, the total light transmittance of the new film is more than 85%; the outer line transmittance of crop light is small, and the 0.3μm wavelength only transmits 20%, so it is often the first choice for PVC bags, while polyethylene (PE) canopy film transmits 60%; after buckling the canopy, the condensation is light, and the impact on light transmission is less than that of PE canopy film, but after a period of use, the plasticizer will adhere to dust and the light transmittance will decrease.

2. Excellent moisture retention, low thermal conductivity, especially low transmittance to long-wave radiation of 6-15μm emitted from the surface at night, only about 20% for PVC plastic bags (over 70% of PE shed film), shed temperature and ground temperature The average temperature increase is 1.23℃ and 1.05℃ higher than that of PE greenhouse film.

3. The air tightness is good, the gas permeability to nitrogen, oxygen and carbon dioxide is 3.0, 9.0 and 75 (×10-14cm3/mm·cm2·S·Pa) respectively, but the water vapor permeability (6.9×103g/mm·24h ·M2·Pa) is larger than LDPE film.

4. High tensile strength, good extensibility and strong wind resistance.

5. Excellent weather resistance, general pvc cosmetic packaging bags can be used for more than 1 year.

6. Good chemical stability, acid and alkali resistance. 7. Good weldability and adhesion, easy for splicing and repairing.

Compared with LDPE shed film, PVC plastic bag has better light transmission, heat preservation and strength; but it has a higher density (1.3g/cm3), a smaller coverage area of the same quality, easy dust absorption, and poor low temperature resistance.