Manufacturing process characteristics of the lates

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Characteristics of the manufacturing process of new generation wood plastic materials

with the increasing scarcity of wood resources, while strengthening the protection of forests and other resources, people fill plastic recycled materials or new materials with wood powder or other natural plant fibers. Natural fiber plastics and products made by special equipment have emerged in the manufacturing of various materials in recent years because of their dual characteristics of plastic and wood, And gradually become the focus of attention and development from all walks of life. Among them, the plastic wood board produced by blending polyethylene, polypropylene resin and wood flour has developed particularly rapidly because it can replace wood in many occasions

after several years of development and application, people have found that ordinary wood plastic materials have poor rigidity compared with wood, while compared with plastic materials, there is also a significant gap in surface finish. At the same time, there are still some problems in the processing process. With the expansion of application fields, how to further improve the properties of wood plastic materials has become the focus of researchers' development. Through experimental application and comparative research, relevant domestic experts found that in the design and manufacture of wood plastic materials, the processing route and material selection should be determined according to the characteristics of molecular structure, so as to realize the imitation of wood and high-quality imitation of the new generation of wood plastic materials. The consumption of magnesium alloy for automobiles produced in North America will reach 160kg. Among them, in the processing process, the orientation of natural plant fibers is the technical key to the production of new wood like wood plastic materials

in the structural design of wood plastic materials, the first consideration is the selection of raw materials. Commonly used plastic varieties include polyvinyl chloride (PVC), polyethylene (PE), polypropylene (PP), ABS and high impact polystyrene (HIPS). The main natural fibers are leftovers and waste materials from agricultural and forestry processing, such as wood flour, rice hull, peanut hull, straw, etc. The cellulose content of rice hull is higher than that of wood flour, and the content of water and lignin is also lower than that of wood flour. Unlike wood flour, the chemical composition changes greatly due to different places of origin and tree species, so the quality is relatively stable. It is more important to consider the length diameter ratio, orientation, content and anisotropy of wood flour fiber. The fibers in wood are long fibers, while wood flour becomes short fibers. The finer the fineness of wood flour, the better the uniformity, but the fiber length and aspect ratio will be greatly reduced. Therefore, the general view that the finer the wood flour, the better is not comprehensive. The key is the molecular orientation arrangement, that is, the fibronectin molecules of wood flour should be arranged in a certain direction, which can effectively improve the strength of rigidity

plant fiber orientation is the key technology in the production of wood plastic materials. From the perspective of morphology and structure, this is also the biggest difference between the new generation of wood plastic materials and wood plastic products (such as fiberboard) that also have packaging functionality and high performance. The fibers in wood are long fibers, which are oriented along the trunk direction, so that the wood has excellent rigidity, strength and bending resistance. In order to make the powdered fiber have the similar reinforcement effect of long fiber, the fineness, length diameter ratio and content of wood powder or rice husk powder should be adjusted and matched in a series. It is found that the combination of wood flour and chaff and the bimodal distribution of fiber length can effectively solve the contradiction of low orientation, poor surface finish, difficult processing and high brittleness and low strength of short fibers when the content of long fibers is high

although the quality of orientation arrangement has a great relationship with raw materials and formulas, the decisive thing is to be guaranteed by equipment, molds and processing conditions. Therefore, not any extruder can meet the production requirements of Tianxian wood like profiles. The design parameters of the extruder used for natural fiber composite wood like materials are very different from those of general plastic profile extruders. The wood fiber content in the materials is high and the fluidity is poor. It is ideal to adopt the ejection method, that is, the materials will overcome the pressure drop in the head where there is a huge pressure generated by the screw, and the die will be ejected from the die. After the die is separated from the open die, the setting die and cooling water are not required, But at this time, the flow passage of the machine head should be long. Due to the high extrusion pressure, the screw, reducer and motor bear a large torque. This ejection method is suitable for producing products with high density. For foamed wood like materials with low density, the traction method is adopted, and the wood fiber content is not greater than 50%. The process is flexible. Through the formula and adjusting the processing conditions, the products produce wood texture, and can be supplemented by cooling technology, so that the processing temperature of the resin can adapt to the characteristics of wood fiber that is not resistant to high temperature. In the process of processing and production, it is required to make the resin (plastic) fully plasticize and flow, make the fiber flow orientation, and do not operate the fiber. Only under this premise can we obtain ideal imitation wood products

the production process of natural fiber composite wood like material is different from the pressing process of fiberboard, which is basically similar to the extrusion process of hard PVC profile. The drying and crushing process of wood flour should be increased. The drying of rice husk is relatively easy, while wood flour has high water content, strong moisture absorption capacity, and high requirements for drying and storage. The crushing method should also be selected according to the different raw materials and final particle size. Since the fineness of wood flour is not as fine as possible, the principle of coarse and fine blending and bimodal distribution should be adopted, and the important thing is that the length diameter ratio should be larger. The length diameter ratio is related to the crushing method. Generally speaking, grinding method is better than hammering method. Extrusion molding must take into account that wood flour is easy to become brittle, carbonized and its strength decreases at high temperature. The temperature resistance of plant fiber should not exceed 180 ~ 200 ℃, and the heating time should be as short as possible. Therefore, the processing temperature and extrusion process conditions must be synchronized with the temperature limit of wood flour

on the whole, the new generation of wood plastic materials developed by using a large number of agricultural waste and a variety of plant fibers can be widely used in building decoration, packaging materials, freight pallets and various public facilities, maintaining the woodiness and woodiness of the wood that should be removed from the convex ball on the experimental machine at this time, as well as the sawable, nailable, planed and bonded wood essence, which is superior to wood in terms of waterproof, corrosion prevention and fire prevention. Therefore, with the increasing tension of wood resources in China, the development of new wood like wood plastic materials with dual advantages of wood and plastic, which can be recycled reversibly, has great social significance and economic value

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