Do You Know Why Outdoor PE Wood Plastic Materials Need So Many Additives

Just like the question on the title, Shanghai Seven Trust wood plastic flooring has done research and development of wood plastic products for a long time before, so I am very interested in this. This is also the reason why the prices of some factories are more expensive in many cases.

Everyone knows that wood plastic materials are composite materials and require many different materials. But why do you need so many additives? (We here refer to the main materials, wood flour and HDPE, as additives.)

1. Wood flour itself is highly water-absorbent and highly polar. PE plastic is non-polar and hydrophobic, so the compatibility between the two when making composite materials is poor, and the adhesion of the interface is poor. It is very small, so it is necessary to use appropriate additives to modify the surface of polymer and wood flour to improve the interface affinity between wood flour and resin.

2. The dispersing effect of high-filled wood powder in molten plastics is poor, and it often exists in a certain aggregate state, which makes the melt fluidity poor, and the extrusion molding process is difficult. It is necessary to add a surface treatment agent to improve the fluidity in order to facilitate the extrusion.

3. The plastic itself also needs to add various additives to improve its processing performance and the performance of the finished product.

The commonly used additives for PE wood plastic materials on the market include the following categories:

One is the coupling agent. It can produce a strong interface between the surface of the plastic and the wood flour; at the same time, it can reduce the water absorption of the wood flour and improve the compatibility and dispersibility of the wood flour and the plastic, so the mechanical properties of the composite material are significantly improved. Commonly used coupling agents mainly include: isocyanate, cumene peroxide, aluminate, phthalate, silane coupling agent, maleic anhydride modified polypropylene (MAN-g-PP), ethylene- Acrylate (EAA). Generally, the adding amount of coupling agent is 1wt%-8wt% of the added amount of wood powder. For example, silane coupling agent can improve the adhesion between plastic and wood powder, improve the dispersibility of wood powder, reduce water absorption, and use alkaline Treating wood flour can only improve the dispersibility of wood flour, but cannot improve the water absorption of wood flour and its adhesion to plastics. It should be noted that the maleate coupling agent and the stearate lubricant will have repulsive reactions, which will result in a decrease in product quality and yield when used together.

The second is plasticizer. It is difficult to process HDPE and wood flour in composite extrusion, and it is often necessary to add plasticizers to improve its processing performance. The molecular structure of plasticizer contains polar and non-polar genes. Under the action of high temperature shearing, it can enter the polymer molecular chain and attract each other through polar genes to form a uniform and stable system. Its longer non-polar genes The insertion of polar molecules weakens the mutual attraction of polymer molecules, making processing easier.

The third is lubricant. Wood plastic materials often need to add lubricants to improve the fluidity of the melt and the surface quality of extruded products. The lubricants used are divided into internal lubricants and external lubricants. The choice of internal lubricant is related to the matrix resin used. It must have good compatibility with the resin at high temperatures, and produce a certain degree of plasticization, reduce the cohesive energy between the molecules in the resin, and weaken the interaction between the molecules. Friction to achieve the purpose of reducing the melt viscosity of the resin and improving the melt fluidity. The external lubricant actually plays the role of lubricating the interface between the resin and the wood powder in the plastic molding process, and its main function is to promote the sliding of the resin particles. Usually a lubricant often has both internal and external lubricating properties. Lubricants have a certain impact on the service life of the mold, barrel, and screw, the production capacity of the extruder, the energy consumption in the production process, the surface finish of the product and the low-temperature impact performance of the profile. Commonly used lubricants include: zinc stearate, ethylene bis fatty acid amide, polyester wax, stearic acid, lead stearate, polyethylene wax, paraffin wax, oxidized polyethylene wax, etc.

The fourth is colorant. In the process of using wood plastic composite materials, the solvent-soluble substances in wood powder can easily migrate to the surface of the product, decolor the product, and eventually turn it into gray. Different products will also produce black spots or rust spots under a certain use environment. Therefore, colorants are also widely used in the production of wood The fifth is heat stabilizer. Since the processing temperature of wood plastic composites is generally above 150°C, wood powder has generally begun to burn at this temperature, so heat stabilizers must be added to prevent the composite products from pyrolysis, scorching and other adverse effects. Now commonly used are heat stabilizers 1010, 168 or composite stabilizers and so on.plastic composite materials. It can make the product have a uniform and stable color, and the decolorization is slow.

Sixth, anti-aging agent. The application of anti-aging agents has also developed rapidly with the improvement of people's requirements for the quality and durability of wood plastic materials. It can make the polymer in the composite material not degrade or decrease the mechanical properties. Commonly used are hindered amine light stabilizers and ultraviolet absorbers.

Seven, other additives. In order for the composite material to maintain a good appearance and perfect performance, it is often necessary to add antibacterial agents, antifungal agents, fillers and so on. The selection of antibacterial agents should consider many factors such as the type of wood flour, the amount of addition, the fungi in the environment where the composite material is used, and the water content of the product. For example, zinc borate can be antiseptic but not algae.

From the perspective of Guangdong WPC flooring, each additive is used to accomplish a specific purpose, whether it is performance, appearance, or cost, and so on. But I hope that we can balance actual use requirements (performance, life, price), develop and produce good products with good quality and moderate prices. To promote the development of the wood plastic industry.

So do you know why outdoor PE wood plastic materials need so many additives?If you want to buy wood plastic materials at an affordable price and good quality, please come to Shanghai Seven Trust, and we will provide you with wood plastic materials that you are satisfied with.

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