Generally, non-toxic PVC zipper bags are flexible when touched by hand, and have a lubricating feeling when touched by hand, and the surface feels waxy; if it is a toxic PVC zipper bag, the color is turbid, or it may appear light yellow, and It feels sticky.
PVC zipper bags dense polyethylene can be used to make zipper bags and all kinds of plastic packaging containers. Such as bottles, cups, plates, boxes, etc.; medium-density polyethylene and low-density polyethylene are mostly used to produce films, and are often combined with other materials to produce various composite materials; in recent years, linear low-density polyethylene (LLDPE) has been developed, especially Suitable for making packaging film, its thickness is 20% thinner than low-density polyethylene. It is a promising plastic packaging material. Polyethylene (PE) Polyethylene is a high-molecular polymer of ethylene and a kind of thermoplastic. Polyethylene is a milky white waxy solid, lighter than water, softer, good water resistance, low temperature resistance, odorless, non-toxic; poor heat resistance, poor film air tightness, sensitive to ultraviolet light, easy to oxidize and age, The thermal shrinkage changes greatly, and the printing performance is poor. According to its density, it can be divided into three types: high-density polyethylene (HDPE), medium-density polyethylene (MDPE) and low-density polyethylene (LDPE). If some plasticizers, stabilizers and other chemical additives are added to polyvinyl chloride resin, a pvc cosmetic packaging bag is made by calendering.
The characteristics of our company’s PVC zipper bag are firstly good light transmission, the new film has a total light transmittance of more than 85%; the outer line transmittance of the crop light is small, and the 0.3μm wavelength only transmits 20%, while the polyethylene (PE) canopy The film transmits 60%; the dew condensation is light after the shed, and the impact on the light transmission is less than that of the PE shed film, but after a period of use, the plasticizer will adhere to dust and the light transmittance will decrease. Secondly, it has excellent moisture retention and low thermal conductivity, especially the low transmittance of 6-15μm long-wave radiation emitted from the surface at night. The PVC zipper bag is only about 20% (the PE film is more than 70%). The average temperature increase is 1.23℃ and 1.05℃ higher than that of PE greenhouse film. There is also good airtightness. The gas permeability to nitrogen, oxygen and carbon dioxide is 3.0, 9.0 and 75 (×10-14cm3/mm·cm2·S·Pa), but water vapor permeability (6.9×103g/mm· 24h·m2·Pa) is larger than LDPE film.