WPC Decking Production Line
Wood-plastic profile is a new type of building decoration material. It is made of PVC, PP, PE, PS, ABS plastic and various plant fibers, which are fully mixed and extruded by wood plastic composite machine. It is suitable for wood construction methods such as drilling, planing, nailing, sawing, bonding and printing. It is green, water-proof, moisture-proof, anti-corrosive, mildew-proof, non-deform-able, flame-retardant, can be recycled and reused.
1. Mainly used in processing Eco-wood, Great Wall panels and other kinds of PVC wood-plastic profiles and wires.
2. Floor, guardrail, pallet, packing box, partition board, door and window cover, kicking line and other fields.
PVC wood plastic extrusion flow:
Raw material+wood powder+additive---mixing---granulating---conical twin screw extruder---profile extrusion mould---cool molding die---vacuum calibration support---belt haul-off---cutter---rack---finished product inspecting&packing
WPC Decking Production Line Main Technical Parameter:
Main motor power(kw)
Understanding the existing problems of wood-plastic composites is helpful to the development of the industry.
With the development of plastic and wood industry in China, people gradually realize that using waste plastics as raw materials in plastic and wood industry is an effective way to solve the recycling of waste plastics. Wood-plastic composites have better mechanical properties than wood and plastics. Wood-plastic products have better dimensional stability, low water absorption, and won't warp and crack like wood. Because the matrix of plastic wood products is thermoplastic, it has incomparable advantages in corrosion resistance and acid-alkali resistance, and its service life is longer. The recycled waste wood-plastic composite products can be added into the new wood-plastic products as a new filler, and its performance will not change much. Wood powder used in plastic wood products is often wood scraps, sawdust and some plant fibers such as peanut shells, coconut shells, sugarcane, flax, jute, hemp and so on, which are produced in the process of wood preparation. The price of fibers needed in plastic wood composite materials is much lower than that of wood raw materials. For plastics, due to the addition of wood powder, its mechanical properties have been greatly improved, such as wear resistance, compared with plastics, an average increase of about 35%, while plastic-wood composite products also have the characteristics of easy processing of plastics, but Plastic-wood materials also have their own limitations and problems.
Problems of Interface Compatibility
The interfacial compatibility has always been the primary focus in the research of wood-plastic composites. Wood flour is composed of cellulose, lignin, hemicellulose, extracts and other components, which contain a large number of hydroxyl groups, resulting in strong surface polarity and water absorption of wood flour. For plastics, the thermoplastic plastics PE, PP, polystyrene (PS), PVC, which are commonly used in the market of plastic and wood products, are all non-polar except PVC. Even PVC has weaker polarity than wood flour. This results in poor interfacial compatibility between wood flour and these thermoplastics. To change the interfacial compatibility between wood flour and plastics, the raw materials should be pretreated first - drying wood flour and plastics to reduce the proportion of moisture residue in composite materials. Secondly, the modification is to be carried out. The general modification methods are physical modification and chemical modification. Physical modification includes physical processing, alkalization treatment, discharge treatment, etc. The principle of physical modification is to reduce the hydroxyl ratio of wood flour surface and the polarity of wood flour surface. Chemical modification methods include coupling agent treatment, compatibilizer treatment, graft modification and so on.
At present, the most widely used coupling agent in the market is maleic anhydride grafted polymer copolymer. Maleic anhydride grafted polymer copolymer can not only react with plastics activity, but also form covalent bonds with hydroxyl groups on the surface of wood flour, thus reducing the polarity of wood flour surface. Coupling agent plays a good bridge role in improving the interfacial compatibility of wood-plastic composites. Wood flour and plastic can be organically combined to improve the mechanical properties of wood-plastic composites. Nevertheless, there is still a big gap between the mechanical properties of wood-plastic composite products and the materials of building structures in some aspects. R&D institutions also need more in-depth and detailed research.
In addition to wood flour and plastics, wood-plastic composite products also need some additives, such as processing modifiers, colorants, plasticizers, compatibilizers, coupling agents, foaming agents and so on. This requires consideration of both cost and performance. Reducing the proportion of thermoplastics and increasing the content of wood flour in composites can reduce costs, but this may also lead to performance degradation. Therefore, in the R&D process, the formulation should be diversified to maximize performance and efficiency.
Classification and Source of Raw Materials
At present, the recycled plastics in the market are mostly mixtures, which will bring difficulties to the reuse of waste plastics. Therefore, in the recycling of plastics, we should broaden the types of plastic recycling and refine the varieties of plastics. For fibers, some manufacturers now use seasonal straw, cotton stalk, rice husk and so on, which should consider the storage of raw materials. Although these materials are much cheaper than wood fibers, there are many problems in storage.
The density of wood-plastic composite products is generally twice that of wood products, and the corresponding production cost of wood-plastic products will also increase. At present, the general method to reduce the density of wood-plastic composites is microporous foaming technology. The main forming methods of microcellular foamed wood-plastic composites are continuous extrusion and injection moulding. The application of foaming technology not only solves the problem of high density of wood-plastic composite products, but also improves the mechanical properties of materials by passivating the crack tip and preventing crack propagation.
Production Equipment and Processing Technology
At present, extrusion, pressing and injection moulding are the methods of producing plastic and wood products on the market. However, the equipment used is either the general production equipment for continuing plastic or the general production equipment for continuing wood, which results in many restrictions on the processing and properties of plastic wood materials. In recent years, many plastic and wood manufacturers have improved their equipment, or customized foreign equipment specializing in the production of plastic and wood. For processing technology, the addition of wood flour will reduce the fluidity of raw materials and hinder the processing process, so lubricants and processing modifiers are generally added to reduce the friction of mixtures, improve the fluidity of melt mixtures and reduce the damage to equipment.
As a new green environmental protection material, wood-plastic composites can be applied in almost all fields of wood products, which provides a broad market space for wood-plastic composites. Moreover, most of the raw materials of Plastic-wood composites use waste recycled plastics and wood powder, which also provides an economic solution to white pollution in China. But there are still many problems to be explored and solved. Wood-plastic composite materials have good mechanical properties, considerable social and economic benefits, and will become a very promising material.