Water soluble PVA film Production Technology and current situation
Water soluble PVA film is a new type plastic product which gets intensive attention in recent years. It is a kind of new and environmental packaging, which with water and biology degradation property .It degraded into CO2 and H2O, and it is a high and new environmental protection product, which get approval from Environmental protection departments of Europe , America and Japan. Water soluble PVA film has great transparency, glossiness, non-charge, high tensile/ tearing strength, good oil resistant performance, excellent gas barrier property and good demould/ Metal plating property. It has wide and unique application in flexible package.
Water soluble film production technology both at home and board
At present, there are two production techniques for PVA film: Solution salivation method (wet process) and Extrusion blown film method (dry process).Both the two production techniques are different from traditional plastic film production. As Polyvinyl Alcohol (PVA) is Water soluble product, its film-making technique is different from thermoplastic plastics.
Solution salivation method
The basic production process for Solution salivation method (wet process) as below: Dissolve PVA- Flow delay coating- Drying (heat treatment) – Stripping- reeling- Finished product.
Solution salivation method is relative simple, but the product’s quality is not easy to control with low film outpour rate, High energy consumption and large Equipment investment.
Extrusion blown film method
The basic production process for(dry process) as below: PVA ,water, plasticizer, lubricant - Forced circulation mixed- Extrusion granulation- Melt extrusion blown film- Modification treatment – winding- finished product.
The products’ quality and production efficiency have been approved than Solution salivation method, but PVA must be treated by modification treatment. Granulation increase add amount of working procedure and auxiliary additives. In whole process, the resin and film need to be heated repeatedly, while keep 15%-35% moisture content. The techniques are complicated and with high consumption of energy.
