Develop plastic and wood composite building materials and make rational use of resources

Plastic-wood composite materials are modified thermoplastic materials filled with wood fibers or plant fibers, and have the advantages of cost and performance of wood and plastics. They can be extruded or pressed into profiles, plates or other products, and can replace wood. And plastic. Over the years, the U.S. construction industry has been looking for a material that is not corroded, warped, easy to maintain, and looks very similar to wood. South Korea and Japan’s paper and wood processing plants have also been looking for sawdust and waste wood. Such reuse, these are to some extent promote and accelerate the research and application development of plastic-wood composite materials. It is one of the most active areas in the plastic extrusion industry to process wood flour-filled mixes into structural and structural profiles. In particular, the production of building profiles is the fastest growing in the market, and its market prospects are very promising.

The impetus for the development of plastic-wood composite materials comes from the rational use of the limited resources of the earth, reducing the amount of raw wood, protecting forests, protecting the environment, and recycling old wood flour and plastics. It is an effective way for the comprehensive utilization of limited resources. Wood fiber and plant fiber are rich in resources, cheap, light in weight, and have little wear on the equipment. The finished product has good dimensional stability, excellent electrical insulation, non-toxic, can be repeatedly processed, can be biodegraded, and will not cause pollution to the environment. Wood fiber has waste wood powder, shavings, and sawdust; vegetable fibers are generally comminuted processed rice straw, peanut shells, coconut shells, sugar cane, flax, jute, etc.; thermoplastics are mainly polyethylene (PE), polypropylene (PP) Polystyrene (PS) and polyvinyl chloride (PVC), including new materials, recycled materials, and composites of both.

China's forest resources are not abundant, and timber reserves are small, so it is difficult to meet the needs of the development of the domestic market. In addition, since February 1998, the United States, Canada, and the European Union and other countries have successively imposed new quarantine standards on wood packaging materials exported from China, requiring fumigation or high-temperature sterilization, or they will refuse to enter the country. The restrictions on timber resources, changes in the market, and environmental protection requirements have promoted the development of plastic-wood composite products represented by plastic pallets for packaging pallets in China.

Wood fibers and plant fibers were originally used as modified fillers because of their low cost and increased plastic rigidity. At present, whether materials can be recycled or not has become one of the important considerations for the selection of materials for industrial users. Plastic-wood composite materials can make full use of limited resources and can be recycled.

The main characteristics of plastic-wood composite materials can be attributed to: durable, long life, similar wood appearance, higher hardness than plastics; excellent physical properties, better stability than wood, no cracks, warping, no wood frugal, Twill; add coloring agent, film or composite surface layer can be made of a variety of colorful products; with thermoplastic processing, easy molding, with a general plastic processing equipment or a slight transformation after the molding process, processing equipment Less investment, easy to promote and apply; similar to the secondary processing of wood, can be cut, adhesive, nailed or bolted, can be painted, product specifications can be adjusted according to user requirements, flexibility; not afraid of insects Antimony, anti-aging, anti-corrosion, water absorption, no moisture deformation; can be reused and recycled, low maintenance costs.

However, wood-plastic composite materials also have its disadvantages: the toughness is lower than that of the parent materials, and the processing equipment, downstream devices, and molds all need to be adjusted accordingly and technologically modified.

At present, the world's largest market for plastic-wood composite materials is in North America. In 2002, the market usage in North America alone reached nearly 320,000 tons. It is expected that by the year 2005, the market demand in North America will increase at a double-digit rate. 2005 The market demand will be double that of 2002, of which the amount of planking (including platforms, slabs, platforms, plates, etc.) already accounts for more than 60% of the total usage. In addition to planking, there are also wallboards, ceilings, decorative panels, footboards, siding, noise barriers for freeways, seashore flooring, architectural forms, moisture barriers, etc. Plastic-wood laminate flooring can be used. In addition, it can also be used for decorative borders, fences and garden handrails, packaging pads and combination trays, as well as furniture (including outdoor open tables and chairs), ship cabin partitions, office partitions, storage boxes, flower boxes, activity racks, Push stacks, blinds, etc.

As plastic-wood composites are environmentally friendly materials, the potential of wood-plastic window frames to replace PVC window frames is considerable. Therefore, it can be foreseen that wood-plastic products replacing PVC and other plastic products will grow as fast as previously plastic products instead of wood products. Therefore, the plastic-wood composite material is an environment-friendly material with a broad market prospect, and its processing technology has become increasingly mature and diversified.