I believe everyone must have heard of PVC under the Efficient pvc soft sheet extrusion line, but it is not clear what it is. In fact, PVC is a material that is widely used in life, and almost everyone has used things made of PVC. And PVC is also widely used in the field of flame retardant because of its own characteristics.
In simple terms, PVC is polyvinyl chloride, a thermoplastic resin polymerized from vinyl chloride under the action of an initiator. It is one of the largest plastic products in the world, and it is cheap and widely used.
PVC products can be divided into two types: rigid PVC and soft PVC. Generally, those with a plasticizer content of less than 10% are called rigid PVC, and those with a plasticizer content of more than 30% are called soft PVC. It should be noted that rigid PVC itself has excellent flame retardant properties, LOI> 45%, no need to add flame retardants without special requirements; while soft PVC needs to add flame retardants due to the presence of plasticizers to achieve Flame retardant requirements.
Due to the wide application and variety of PVC products, in order to meet different needs, different PVC molding processes are required. China GWELL, as a plastic extruder manufacturer, will briefly introduce the application of PVC products.
Application of PVC products
1. PVC Calendering Products
After PVC and additives are mixed and plasticized, a three-roll or four-roll calender is used to form a film with a specified thickness. Such flame retardant products mainly include electrical tape, light box cloth, toy film, conveyor belt, wallpaper and so on.
2.PVC coated products
The PVC coating is made by hot-melting and stirring plastic particles into a paste, uniformly coating it on the T/C knitted fabric base according to the specified thickness, and then post-processing. Such flame retardant products mainly include artificial leather, sofa and car leather, floor leather, outdoor tents, playground inflatable facilities, and paving materials for buildings.
3. PVC extrusion products
This process is mainly used for the processing of PVC wires and cables and PVC pipes.
4. PVC injection molding products
The products of this kind of craft mainly include pipe fittings, joints, junction boxes, foot pads, oxygen masks, toys, auto parts and so on.
5. PVC foam products
When soft PVC is kneaded, an appropriate amount of foaming agent is added to make a PVC sheet, which is foamed and formed into a foamed plastic, which can be made into foamed board, foam slippers, sandals, insoles, shock-proof buffer packaging and other materials.
6. PVC sheet, profile
Add auxiliaries to PVC, and after mixing, extruder can extrude hard pipes, special-shaped pipes and corrugated pipes of various diameters. The rolled sheets can also be overlapped and hot-pressed to make hard plates of various thicknesses, such as storage tanks, air ducts, doors and windows, etc.
three. Source of Efficient pvc soft sheet extrusion line material
Sources of raw materials for extruded sheets and sheets: mainly thermoplastics, hard or soft polyethylene, polyethylene, polypropylene PP plastics, ABS plastics, polycarbonate PC plastics, acrylic resins, etc. It can be filling, blending modification, foaming material, etc. Plates and sheets can be divided into: single-layer or multi-layer, flat or corrugated, special-shaped interface, etc., according to their shape and structure. The general width of plates and sheets is 1-1.5 meters, and the maximum width can reach 3-4 meters. It is customary to say 1mm. Sheets with the above thickness are plates, and those with 0.25-1mm are sheets.
Advantages of extrusion sheet and sheet forming: Compared with other forming methods, the equipment used in the production line is relatively simple, the input cost is lower than that of the calendering method and the lamination method, the production efficiency is high, and the sheet and sheet have better mechanical properties and optical properties. performance.
PVC modification method
Polyvinyl chloride (PVC or vinyl) of the Efficient pvc soft sheet extrusion line is an economical and versatile thermoplastic polymer widely used in the building and construction industry, production of window and door profiles, pipes (potable water and waste water), wire and cable insulation, medical equipment, etc. It is the world’s three major thermoplastic materials together with polyethylene and polypropylene. However, due to its poor processing and forming properties, such as high melt viscosity, poor fluidity, poor thermal stability, easy thermal decomposition, poor aging resistance, easy to become brittle, hard, cracked, poor toughness, cold resistance Not good, so PVC modification is generally required to make up for the above shortcomings.
1. Chemical modification
Chemical modification includes copolymerization modification, grafting reaction and chlorination.
- Copolymerization modification: that is, copolymerization of vinyl chloride monomer and other monomers. For example, it is copolymerized with vinyl acetate, vinylidene chloride, acrylonitrile, acrylate, maleic anhydride and other monomers to improve the molding processability, or to reduce the molding temperature, or to develop new uses, or to appear as new materials.
- Grafting reaction: Introduce another monomer group, or another polymer, on the side chain of PVC to carry out the grafting reaction. For example, ethylene-vinyl acetate and vinyl chloride are grafted, and the number and degree of polymerization of vinyl chloride grafted parts are controlled to improve the impact performance, low temperature brittleness, and aging resistance of this modified material.
- Chlorination: pvc soft sheet extrusion line uses water-phase suspension method (or gas-phase method) for chlorination of PVC to increase the chlorine content from 57% to about 65%. The purpose of this modification is to improve PVC The heat resistance is 35-40℃ higher than the original PVC, which is called chlorinated polyvinyl chloride (CPVC). The density of CPVC is larger than that of PVC, which is 1.7 g/cm3. Its flame retardant performance is better than that of PVC, and its tensile strength is also better than that of PVC. CPVC can be used for pipes, sheets, profiles, foam materials, adhesives, coatings, modifiers, etc.
2. Physical modification
Physical modification is to improve its performance by adding various additives or filling, blending and reinforcing.
- For example, adding ACR to improve the molding performance of PVC materials; adding internal and external lubricants or polyethylene wax to improve the viscosity and fluidity of materials; adding thermal stabilizers to improve the thermal stability of materials during molding and reduce their decomposition. temperature; adding antioxidants and anti-ultraviolet agents to improve the aging resistance life of products; adding plasticizers to improve the plasticizing properties of materials and increase the softness of products. Filling modification is to improve certain properties by adding inorganic or organic fillers.
- For example, adding wood powder fillers can reduce the proportion of PVC products, which is close to wood; adding metal powders, such as copper powder and aluminum powder, can improve the electrical conductivity of products; adding iron oxide magnetic powders can improve the magnetic properties of products; adding calcium carbide can improve the hardness of products, while reducing the material cost; adding red mud improves the heat resistance and light aging resistance of the product, and reduces the material cost at the same time.
- For example, other polymers that can be modified by blending with PVC are acrylonitrile-butadiene-styrene copolymer (ABS), methyl methacrylate-butadiene-styrene copolymer (MBS), polyacrylic acid Ester, chlorinated polyethylene (CPE), ethylene-vinyl acetate copolymer (EVA), butadiene rubber, ethylene propylene rubber, chlorinated polyvinyl chloride (CPVC), dioctyl maleate, etc.
- In addition, PVC modification methods such as reinforcement modification, crosslinking modification, foaming modification, radiation modification, etc. can also be used to improve the performance of PVC of Efficient PVC soft sheet extrusion line.