- Jan 04, 2018 -
Multi-layer co-extruded composite film
The traditional multi-layer composite packaging film used in the production process of adhesives, solvents, volatile, easy to cause environmental pollution. With the growing voice of environmental protection, requiring the reduction of production waste and packaging waste, so multi-layer co-extruded packaging materials manufacturing technology has been rapid development.
At present, the co-extrusion blown films of PA, EVOH, PVDC and PE, EVA, PP and other multi-layer combinations swept the functional packaging film market with reasonable, economical and reliable performance. In particular, some asymmetric multi-layer co-extruded film structure, but also with its excellent composite peel strength, outstanding barrier properties, superior resistance to environmental and chemical resistance, low-cost processability, the appropriate secondary processing, Replaced or simplified many dry-based composite packaging film market.
Multi-layer co-extruded composite film typical characteristics embodied in seven aspects:
(1) The use of multiple layers of the same polymer instead of a single layer of polymer in the barrier layer improves the barrier stability.
(2) When it is confirmed that the thickness of the barrier layer is sufficient to satisfy the barrier requirement, then replacing the single layer polymer with the same layer of the same polymer in the barrier layer can reduce the cost of the barrier film with high added value.
(3) The use of two different polymers in the barrier layer to replace a single species of polymer significantly improves the barrier properties of the film. For example, the combination of the EVOH layer and the PA layer can not only maintain the puncture resistance of the PA, but also increase the strength of the EVOH by interposing the EVOH layer in the middle of the PE layer, thereby improving the crack resistance of the EVOH. For a five-layer structure to use two different barrier layers at the same time, one of the layers can only be the outermost layer. In order to prevent the outer barrier film from being damaged by external forces, the barrier effect is reduced. Generally, Thickness method to make up, resulting in increased costs.
(4) The heat seal layer and the composite layer are each divided into two groups. One group uses less expensive polymers instead of the more expensive polymers to reduce the cost of the film while maintaining the strength of the film. The other group uses functional polymers that meet their functional requirements. Use the concept of multi-layer more economical composite film. For example, comparing two kilograms of one weight film, a five-layer film requires about 19% more material than a seven-layer film.
(5) The use of more layers of coextruded films can improve the performance of coextruded films below five layers. For example, the use of additional adhesive layers can increase the barrier properties of the film by increasing the water vapor barrier of the film. Another advantage obtained at the same time is that the film can be made softer and feel good.
(6) Use of more layers of coextruded film can improve the five layers of PA coextruded film resistance to stress warpage. At the same time to meet the bag and other secondary processing needs.
(7) In addition to the functions of the dry-type composite film in addition to printing, the composite process is simplified, the composite structure tends to be flexible, the functions tend to be diverse, the cost is obviously reduced, the safety is more, the more in line with the health and environmental protection Requirements, social and economic benefits are more significant.
Therefore, the multi-layer co-extruded composite film to meet many of the more demanding packaging applications, more in line with market demand, the packaging industry will have a profound impact on technological progress and development.
In China, multi-layer coextrusion barrier packaging films are widely used, so multi-layer co-extrusion technology in China will have a lot of space for application. Multi-layer co-extruded composite film has the same function as dry composite film, but also have more flexibility, superior environmental performance, can replace dry composite film or reduce the number of dry compound, has become a trend.
Vigorously develop multi-layer coextrusion plastic composite film blowing equipment, can replace the dry compound, plastic lamination, vacuum aluminum and other composite equipment to produce special requirements of flexible packaging materials, packaging materials to simplify the production process, save energy and reduce the plant And human resources, reduce production costs, help to save resources and control environmental pollution, reduce occupational sickness, avoid dry compound adhesives and solvents, the residual harmful substances to pollute the packaged goods, enhance the competitiveness of the export of goods and foreign exchange earning capacity, thus promoting China Packaging materials technology upgrade.