let me analyze the formula technology of PVC wood plastic products for everyone
let me analyze the formula technology of PVC wood plastic products for everyone,Our PVC wood-plastic products are commonly used in home improvement and park walkways. Wood-plastic products are indispensable in our daily lives. Environmental protection issues will follow. Below I will analyze the formula of PVC wood-plastic products for you. You are worth collecting!
As we all know, home decoration has become a problem that each of us must face. In recent years, there have been more and more incidents of home decoration materials polluting the indoor environment, causing cancer and cancer. The main culprit is home decoration plates. So, what are the characteristics and advantages of PVC downstream products? As we all know, PVC green home improvement materials are mainly divided into two types of products: PVC wood plastic and PVC stone plastic. Among them, PVC wood plastic products are the most widely used. Of course, in addition to PVC wood plastic products, there are other products such as stone plastic, which have become a new type of green environmental protection materials in the home improvement industry.
PVC wood-plastic composite material is to use polyvinyl chloride resin instead of the usual resin adhesive and 20% -35% wood flour, rice husk, straw and other waste plant fibers to form a new wood material, which is then extruded, molded, injection molded Plastic processing technology such as molding produces plates or profiles, which are mainly used in interior decoration to replace solid wood and artificial boards. The biggest feature of PVC wood-plastic composite material is that it has the dual advantages of two different materials of natural wood and resin materials. It overcomes the poor dimensional stability of wood, flammability, moisture, perishability, decay, and breeding. At the same time, mold and other shortcomings also avoid the deficiencies of simple resin materials such as high temperature creep and low temperature brittleness, and truly achieve zero formaldehyde.
WPC
The wood powder used for wood plastic includes wood powder, bamboo powder, rice husk powder, wheat straw, peanut shell, bagasse, etc. The resin used for wood plastic includes PVC, PE, PP, of which PE accounts for 70% and PVC accounts for 13 %, PP accounts for 17%. As the price of oil rises, the prices of PE and PP, which are made of petroleum, increase, while the price of PVC is stable, which gives PVC-based plastic-wood composites a development opportunity. Of course, it is not low cost. We can ignore these and have a great impact on the physical and mechanical properties of the product. We can analyze it through actual production.
First of all, we need to know that the main ingredients of wood flour are cellulose + lignin + hemicellulose. In addition, other organic matter and moisture must be added with resin powder in real life.
Mix the mixture of plant fibers such as PVC + wood flour and so on for 5 minutes on a 170 ℃ double-roll plastic mixer, take tablets, tablet, sample preparation, notch impact strength according to GB1843-80 standard in ZBC-25B pendulum impact test It is carried out on the machine; the tensile properties are carried out on the CMT6104 universal electronic testing machine according to the GB / T1040-92 standard. The bending performance is tested according to GB1042-79 standard. The impact spline is cooled with liquid nitrogen, then brittlely broken, vacuum gold-plated on the cross-section, and scanned by a scanning electron microscope.
1. The influence variable of wood flour's moisture in production
Through experiments, we found that when wood flour is heated, the water evaporates first, and then the easily decomposable part of lignin decomposes, further heating the cellulose to oxidative decomposition, and finally the lignin decomposes. When the modified plastic is filled with wood powder that has not been dried or dried in place, due to the presence of residual water in the wood powder and the low-boiling volatile substances in the wood powder, there are considerable bubbles in the sample, so The mechanical properties of the material are obviously affected; at the same time, proper heating treatment can also avoid the phenomenon of "burning" during the processing, and ensure smooth processing, bright products and normal color. Therefore, wood flour must be dried before filling.
At the initial stage of heating, the weight loss value of wood and bamboo powder is relatively large, because the moisture of bamboo powder evaporates during heating. After 1 hour, the weight loss value of bamboo powder is basically unchanged. The weight loss of wood powder at 110 ℃ and 130 ℃ is mainly Water evaporates. At a temperature of 150 ° C, the weight loss value of bamboo flour is relatively large at the initial stage of heating, mainly due to the loss of moisture, but as the heating time is extended, the weight loss value of bamboo flour becomes relatively smooth. Low boiling point volatile substances. When heating, if the temperature is low, the time is short, the wood powder loss is less than 3%. If the temperature is high, the heating time is long, the wood powder is infinitely reduced, which is meaningless and uneconomical. Considering the combination of performance and economy, the heating temperature of wood flour is 110 ℃, 130 ℃, and the reduction range is 5-10%.
Second, the influence of the choice of resin on the mechanical properties of the product
The high filling of wood powder will affect the plasticizing performance and processing fluidity of PVC. The resin type must be selected according to the melt flow rate (MFR) of the resin. MFR also has a certain influence on the performance of the composite material. Under the same processing conditions, The MFR of the resin is higher, the overall wettability of the wood powder is better, and the distribution of the wood powder is more uniform, and the wettability and distribution of the wood powder affect the mechanical properties of the composite material, especially the impact strength.
The lower the degree of polymerization of polyvinyl chloride, the higher the MFR of the resin. It is not difficult to see from the parameters provided by PVC resin manufacturers that the viscosity number of PVC SG-7 or PVC SG-8 is lower and the MFR is higher. Therefore, PVC SG -7 or PVC SG-8 is more suitable for matrix resin of PVC / wood plastic composite material.
3. The influence of wood flour selection on the mechanical properties of products
Wood powder is made by mechanical crushing. The force of wood powder of different particle size in the crushing process is different. Therefore, the wood powder of different particle size has different surface roughness and length-to-diameter ratio. The degree of damage suffered by the "microbubble structure" is different. The larger the particle size of wood powder, the greater the roughness of its surface. The effect of the roughness of the surface of the wood on performance is:
① Good impregnation of wood and plastic;
② Deep interface diffusion and mechanical interlocking are formed at the interface.
If a deep interface diffusion and mechanical interlock cannot be formed at the interface, it means that a cavity is formed at the interface, resulting in a decrease in material performance. We use 60 mesh, 100 mesh, 300 mesh wood powder to fill PVC, with the following formula
PVC powder SG-7 100
Stabilizer 3.5
Internal and external lubricant 0.5 ~ 2.0
AC foaming agent 0.3 ~ 0.5
ACR foam processing aid 5.0 ~ 8.0
Packing 4.0 ~ 6.0
Flame retardant 2.0 ~ 3.0
Nucleating agent 0.2 ~ 0.7
Plasticizer 5.0 ~ 10.0
Modified wood powder 20.0 ~ 30.0
Internal and external lubricant 0.5 ~ 2.0
AC foaming agent 0.3 ~ 0.5
ACR foam processing aid 5.0 ~ 8.0
Packing 4.0 ~ 6.0
Flame retardant 2.0 ~ 3.0
Nucleating agent 0.2 ~ 0.7
Plasticizer 5.0 ~ 10.0
Modified wood powder 20.0 ~ 30.0
We found that with the change of the particle size of the filled PVC wood powder, the impact strength and bending strength of the PVC / wood powder composite material first increased and then declined. Powder, high surface roughness, loose structure, PVC resin failed to penetrate wood powder, more exposed particles, more voids around wood powder; 300 mesh wood powder, small particle size, wood powder is easy to reunite; these defects Stress concentration, easy to break under a small force. The 100-mesh wood powder has a moderate particle size and good compatibility between the PVC resin and the wood powder interface. Therefore, the maximum impact strength and bending strength appear.
Through experiments, we have concluded that: PVC SG-7 or PVC SG-8 is more suitable for the matrix resin of PVC / wood-plastic composite materials; 100 mesh wood powder, moderate particle size, good compatibility with PVC resin, impact strength and bending strength The maximum value appears; the drying temperature of wood powder filled PVC is 110 ℃.
The difference between PE wood plastic and PVC wood plastic
The advantages of PE wood plastic:
PE wood-plastic material has excellent waterproof and anti-corrosion properties, high hardness, and easy to deform when heated, but it is considered appropriate to use thickened or porous hollow structure.
Disadvantages of PE wood plastic
1. Poor anti-oxidation and anti-photodegradation capabilities, even if antioxidants and UV are added, the effect is not ideal, and it will affect the strength and color fastness of the product;
2. Limited years of outdoor survival
3. The appearance of the product is pure in color, without woodiness, and the appearance is poor.
Advantages of PVC wood plastic
1. PVC wood plastic products can be made of new materials or old materials (while PE is made of new materials, the cost is higher, and the product has no way to enter the market), the modification is relatively easy, and the amount added depends on the output .
2. PVC can be made into low-foam wood-plastic products, so the cost is lower, and it is suitable to use co-extrusion (double-material multi-material co-extrusion or steel-plastic co-extrusion), which has good strength and wood grain.
3. PVC can be secondary processed, and various appearance patterns or paints cover UV paint. The product is beautiful and has good color fastness.
4. The waterproof and anticorrosive properties of PVC wood plastic products are as good.
The difference between PE wood plastic and PVC wood plastic
1. The manufacturing method is different: the preparation of PE wood plastic products mainly purchases cold push method, PVC wood plastic products can be divided into vacuum forming, cold push method and three roll suppression.
2. Raw materials fail: PE wood-plastic materials are mainly made of PE secondary and tertiary recycled materials plus wood powder, calcium powder and a small amount of modifier. The materials used to make PVC wood-plastic materials are mainly PVC resin powder, PVC recycled materials, wood powder , Stone powder and some modifiers, etc.
3. Different performances: PE wood-plastic products are heavy, have high hardness, high brittleness, and large creep. PVC wood-plastic products are light in weight, poor in hardness, good in toughness, have creep, and are not as big as PE wood-plastic products.
4. Different uses: PE wood-plastic products are mainly based on outdoor garden construction, green wood can be used as guardrails, floors, trash cans, flower ponds, trays, etc. PVC wood-plastic products are mainly interior decoration, such as doors, floors, Foot line, door cover, etc.
5. WPC also has a better category-ABS WPC. ABS WPC is easy to process and has good strength. It can also be used for wood grain effect, which is not easy to damage.
Polyethylene wax
Sino wax wood plastic special polyethylene wax
Product advantages
1. High softening point, low viscosity, large molecular weight, and small heat loss.
2. It has strong external lubricating effect. Compared with ordinary conventional polyethylene wax, it can delay plasticization and reduce torque.
3. It is easy to disperse and improve product gloss.
4. Good compatibility and resistance to precipitation.
5. Good mold release, good metal stripping, and long continuous production time.
6. Good thermal stability in the later stage, free of oligomers, paraffin, etc. No precipitation, no migration.
7. Environmental protection, passed ROHS and heavy metal detection.
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