At present, high barrier packaging materials include aluminum film, polyvinylidene chloride two (PVDC) coating film, ethylene vinyl alcohol copolymer (EVOH) Co extrusion film and nylon and polyvinyl alcohol (PVA) coating film.
①Aluminum film
Advantages: the best barrier properties, can effectively prevent ultraviolet radiation.
Disadvantages: opaque, resistance, high cost. The composite aluminum film is difficult to be recycled, while aluminum waste brings pollution and wastes the polyolefin resin.
②EVOHFive layer coextrusion film
Advantages: excellent barrier properties, excellent oil resistance and organic solvent properties, antistatic properties, can be recycled, incineration only produce CO2 and H2O, is an excellent green packaging materials.
Deficiency: when the ambient temperature is relatively high, the barrier performance becomes sharply worse, so it is not suitable to be used alone. The investment of imported EVOH resin and imported multi layer co extrusion equipment is very expensive, resulting in high cost of products.
③PVDCCoating film
Advantages: at the same time, it has good barrier oxygen and barrier water vapor performance, coating can be heat sealed, low cost.
Lack of special equipment required: coating; PVDC coating composite film not only itself cannot recycle, but also make its recovery could film recycling other compound (such as NY, PET, BOPP, PE, CPP etc.) is not recycling; not melting granulating recycling, waste will produce hydrogen chloride, dioxin as for humans and the surrounding environment of toxic and harmful substances in the incineration.
④nylon
Advantages: good oxygen barrier properties, water vapor barrier properties improved, oil resistance, solvent resistance.
Insufficient: the membrane forming process is single, the recovery is difficult, and the cost is higher.
⑤ Polyvinyl alcohol (PVA) coating film
Advantage：
1. It has excellent barrier to oxygen, nitrogen, hydrogen and carbon dioxide. Its oxygen barrier performance is better than that of PVDC (polyvinylidene chloride two) coating film, and is better than EVOH (ethylene vinyl alcohol copolymer) five layer co extrusion film. Its oxygen barrier property is the best among all kinds of resin film, comparable to aluminum foil, glass, alumina film and silicon oxide film.
2, low cost. Polyvinyl alcohol (PVA) coated composite film production far less than the cost of packaging materials of paper plastic composite, aluminum plastic composite structure of the production cost is much lower than that of EVOH coextrusion film production cost is lower than that of composite films with PVDC coating cost.
3, environmental protection first class. Polyvinyl alcohol (PVA) composition of high barrier aqueous coating liquid for carbon, oxygen, hydrogen and silicon, biodegradable, Recyclable recycling, burning only generates carbon dioxide and water, and other substances harmful to the environment and human health, no pollution, is an ideal environment-friendly high barrier packaging materials.
4, colorless, transparent good. With excellent resistance to oil, organic solvent. It has good antistatic performance.
Due to the addition of nano inorganic powder in PVA aqueous coating liquid, bonding strength of the film water resistance, ultraviolet and infrared reflectance, wear resistance, permeability resistance, PVA coating and film have been significantly improved.
Insufficient: because the coating is thin, so the heat sealing coating; after modification, PVA coating sensitivity to water decreased significantly, in order to maintain the oxygen barrier effect is the best, still with polyolefin plastic film (such as BOPP, CPP, PE etc.) to be protected as well.
