Generally speaking, a multilayer material is considered to be a composite material with special properties formed by giving one or more layers of other materials with the same or different properties on one layer of material. Due to the different properties of the materials in each layer, the multi-layer materials can complement each other in performance, so that the composite material has a specific appearance or performance. Such as special color, pattern, touch or high strength, high hardness, high wear resistance, high heat resistance, excellent oxidation resistance and water resistance, etc. At present, there are few researches on multilayer wood-plastic composite materials at home and abroad, and there is no clear definition of multilayer wood-plastic composite materials.
If the composite theory of multi-layer materials can be combined with the preparation technology of wood-plastic composite materials, the advantages of wood-plastic composite materials can be brought into play, and its shortcomings can be overcome or avoided.Design and prepare multi-layer wood-plastic composite materials with multi-layer structure and special properties. In order to expand its application range, develop and prepare value-added and functional wood-plastic composite materials. Provide a new and important way.
As a traditional technique for preparing wood-plastic composites, thermoforming has been widely used in the preparation of wood-plastic composites. Compared with the extrusion process of wood-plastic composite materials, thermoforming has lower requirements on the raw materials for preparing wood-plastic composite materials, and can use a large amount of wood fiber or plant fibers such as crop rice chips and peanut shells to reduce the amount of plastic used ; It can prepare large-format wood-plastic composite materials such as wood-plastic door panels, wood-plastic templates, and wood-plastic trays. Some researchers at home and abroad have used this method to prepare laminated wood-plastic composite materials.