PVC material is polyvinyl chloride, which is one of the largest plastic products in the world. It is cheap and widely used. Polyvinyl chloride resin is white or light yellow powder, which cannot be used alone and must be modified. PVC is a white powder with an amorphous structure, a small degree of branching, and poor stability to light and heat. Different additives can be added according to different uses, and PVC plastics can exhibit different physical and mechanical properties. Adding an appropriate amount of plasticizer to polyvinyl chloride resin can make a variety of hard, soft and transparent products.
PVC, the full name is Polyvinylchloride, the main component is polyvinyl chloride, and other components are added to enhance its heat resistance, toughness, ductility, etc. The top layer of this surface film is lacquer, the main component in the middle is polyvinyl chloride, and the bottom layer is a back coating adhesive. It is a well-loved, popular and widely used synthetic material in the world today. Its global usage is the second highest among all synthetic materials. According to statistics, in 1995 alone, the production of PVC in Europe was about 5 million tons, while its consumption was 5.3 million tons. In Germany, PVC production and consumption average 1.4 million tons. PVC is being produced and applied worldwide at a growth rate of 4 percent . The growth rate of PVC in Southeast Asia is particularly significant, thanks to the urgent need for infrastructure construction in Southeast Asian countries. Among the materials that can produce three-dimensional surface films, PVC is the most suitable material.
PVC was first discovered in 1835 by a famous French scientist (Henri Victor Regnault). This new material was also discovered by another German scientist (Eugen Baumann) in 1872. At that time, the pvc material was a white solid, which was extremely fragile and had no practical application. At the beginning of the 20th century, a group of chemists such as Russian chemists (Ivan Ostromislensky) and Fritz Klatte tried to change the fragility of pvc and make it a commercial product, but they all failed.
Until 1926, Waldo Semon (BF Goodrich Company) in the United States synthesized PVC and applied for a patent in the United States. He solved the fragility of pvc by synthesizing various additives, and increased the expansion of pvc material products, making it have basis for product commercialization. In 1931, Germany began to produce pvc by the emulsion method, and in 1941, the United States began to produce pvc by the flotation method. From this, pvc material-related products began to be widely used in production and life applications. With the continuous development of science and technology, the current production and synthesis of pvc has been replaced by the bulk synthesis method, making it more efficient and greatly reducing the cost.
The density of pure PVC is 1.4g/cmsup3, and the density of PVC plastic parts with plasticizers and fillers is generally 1.15-2.00g/cmsup3.
Rigid PVC has good tensile, bending, compression and impact resistance, and can be used alone as a structural material.
The softness, elongation at break, and cold resistance of soft PVC will increase, but the brittleness, hardness, and tensile strength will decrease.
Polyvinyl chloride has good electrical insulation properties, can be used as low-frequency insulation material, and its chemical stability is also good. Due to the poor thermal stability of polyvinyl chloride, long-term heating will cause decomposition, release HCL gas, and make polyvinyl chloride discolor, so its application range is narrow, and the operating temperature is generally between -15 and 55 degrees.
PVC is polyvinyl chloride, which is a plastic product synthesized from 43 percent oil and 57 percent salt. Compared with other types of plastic products, PVC uses raw materials more effectively and reduces fuel consumption. At the same time, the energy consumption of PVC manufacturing is also very low. And in the later period of use of PVC products, it can be recycled and converted into other new products or incinerated to obtain energy.
Specific gravity
1.38 g/cm3, molding shrinkage: 0.6-1.5 percent , molding temperature: 160-190 degree .
Features
Excellent mechanical properties and electrical properties, strong acid and alkali resistance, good chemical stability, but low softening point. Suitable for making thin plates, wire and cable insulation layers, seals, etc.
Molding characteristics
1. Amorphous materials have low moisture absorption and poor fluidity. In order to improve fluidity and prevent bubbles, the plastic can be pre-dried. The casting system of the mold should be thick and short, the gate section should be large, and there should be no dead corners. The mold must be cooled and the surface is chrome-plated;
2. Due to its corrosive and fluid characteristics, it is best to use special equipment and molds. All products must be added with different types and quantities of additives as required;
3. It is very easy to decompose, and it is easier to decompose when it is in contact with steel and copper at a temperature of 200 degrees. When decomposing, corrosion, irritating gas, and forming temperature range are small;
4. When using a screw type injection machine nozzle, the hole diameter should be large to prevent material stagnation in dead corners. It is better without inserts, if there are inserts, it should be preheated.
PVC can be divided into soft PVC and hard PVC. Among them, hard PVC accounts for about 2/3 of the market, and soft PVC accounts for 1/3. Soft PVC is generally used for the surface of floors, ceilings and leather, but because soft PVC contains softeners (this is also the difference between soft PVC and hard PVC), it is easy to become brittle and difficult to store, so its scope of use is limited. Hard PVC does not contain softeners, so it has good flexibility, easy to form, not easy to be brittle, non-toxic and pollution-free, and has a long storage time, so it has great development and application value. The essence of PVC is a vacuum blister film, which is used for the surface packaging of various panels, so it is also called decorative film and adhesive film, and is used in many industries such as building materials, packaging, and medicine. Among them, the building materials industry accounts for the largest proportion, accounting for 60 percent , followed by the packaging industry, and several other small-scale application industries.
Polyvinyl chloride molecules contain chlorine atoms. Due to the dipole effect of the C-CL bond, it is a highly polar material. PVC has good acid and alkali resistance, wear resistance, flame resistance and insulation properties, but poor light and thermal stability. Commercially, there are four methods for preparing PVC: suspension method, bulk method, emulsion method and solution method. The suspension method is the most common, and most of the PVC resins used are of this type. Its products are divided into hard, semi-hard and soft materials according to the amount of plasticizer (generally dibutyl phthalate and dioctyl phthalate). Rigid PVC contains 10-25 percent plasticizer, semi-rigid PVC is 30-40 percent , and soft PVC is 40-70 percent . All PVC products must contain a certain amount of stabilizers to avoid degradation during processing. Plasticizers in soft PVC products soften the polymer. The choice of plasticizer, or the combination of plasticizers, is ultimately determined by the desired properties of the finished product. Most plasticizers also function as processing aids to some extent. Plasticizers reduce the melting temperature and viscosity of the resin, which prevents the resin from sticking to the metal parts of the processing equipment.
As mentioned above, PVC is a white powder with an amorphous structure. The glass transition temperature is 7790 degree , and it begins to decompose at about 170 degree . When it is above 100 degree or exposed to sunlight for a long time, it will decompose to generate hydrogen chloride, and further autocatalytic decomposition. , causing discoloration, and the physical and mechanical properties also decline rapidly. In practical applications, stabilizers and other additives must be added to improve the stability to heat and light. This is called PVC modification. PVC products, whether injection molding or extrusion, especially PVC material products with special requirements, strictly speaking, the performance of PVC materials should belong to Customer-designed, especially designed to meet the different requirements of each user, providing PVC solutions , that is, there are different formulations to modify. PVC materials with special requirements generally need to be imported from abroad. With the continuous research and development and technology accumulation of major scientific research institutes and production units in my country, the formulation design and manufacture of domestic PVC modified materials have reached the international advanced level, and emerging Companies with independent intellectual property rights such as Xuzhou Hanyong New Materials Co., Ltd. have completely replaced imported materials, and many products have been exported abroad. Because PVC will be added with stabilizers during production, but the stabilizers are divided into non-toxic and toxic. Only when toxic stabilizers such as lead salts are added, will there be hidden dangers. However, PVC products are mixed, and some small enterprises use lead salt as a stabilizer, which makes it difficult to meet relevant hygiene standards.
Due to its high chemical stability, it can be used to make anti-corrosion pipelines, pipe fittings, oil pipelines, centrifugal pumps and blowers. The rigid board of PVC is widely used in the chemical industry to make the lining of various storage tanks, corrugated boards of buildings, door and window structures, wall decorations and other building materials. Due to its excellent electrical insulation properties, it can be used in the manufacture of plugs, sockets, switches and cables in the electrical and electronic industries. In daily life, PVC is used to make sandals, raincoats, toys and artificial leather, etc.!
Polyvinyl chloride is synthesized from acetylene gas and hydrogen chloride, and then polymerized. Has high mechanical strength and good corrosion resistance. It can be used to make waste gas sewage and detoxification towers, gas and liquid conveying pipes in chemical, textile and other industries, and can also replace other corrosion-resistant materials to make storage tanks, centrifugal pumps, fans and joints. When the plasticizer is added in an amount of 30 percent to 40 percent , soft polyvinyl chloride is obtained, which has high elongation, soft products, and good corrosion resistance and electrical insulation. Industrial packaging, agricultural seedling raising and daily raincoats, tablecloths, etc., can also be used to make acid and alkali resistant hoses, cable sheaths, insulating layers, etc.
Polyvinyl chloride is also used in solar hot water bags, through its light-absorbing properties, it is made into hot water bags for bathing
Diverse appearance
In this sense, the market prospect of PVC film is very promising. With the development of the times, PVC is gradually winning the favor of people with its good performance, simple craftsmanship and many other advantages, and has been accepted and recognized by more and more people. In Europe and the United States, PVC is the darling of the construction industry. , PVC can be seen everywhere in people's daily life. PVC not only can express the color of nature, but also can express the color of people's fantasy. In Germany, 40 percent of furniture is made of PVC as the surface material. Seeing those desks, bookshelves, sofas, and kitchen cabinets with natural colors, gorgeous colors, rich and diverse, beautiful patterns, elegant and high-end styles, no one will I will associate them with the devastated "white garbage" on the street, and I will never think that it is the PVC blister film that gives them such a beautiful coat.
Strict craftsmanship
There are two important reasons why PVC can be widely used in the building materials industry: one is the unique properties of PVC (rainproof, fire-resistant, anti-static, easy to form), and the other is the characteristics of low input and high output of PVC. PVC film has high light resistance and fire resistance, which guarantees the high quality of PVC film. So comprehensively, PVC is actually a low-input, high-yield product.
Melting temperature: 185205 degree Mould temperature: 2050 degree
Injection pressure: up to 1500bar Holding pressure: up to 1000bar Injection speed: In order to avoid material degradation, it is generally necessary to use a considerable injection speed.
Runners and gates: All conventional gates can be used. If machining smaller parts, it is better to use a tip gate or a submerged gate; for thicker parts, a fan gate is better. The minimum diameter of the tip gate or submerged gate should be 1mm; the thickness of the fan gate should not be less than 1mm.
Unique performance
What is the difference between PVC film and ordinary adhesive film? Ordinary adhesive film is directly attached to the surface of the board with glue at room temperature, so after one or two years, the film is easy to fall off. The PVC film is pressed on the surface of the board at a high temperature of 110 degrees by a special vacuum laminator, so it is not easy to fall off.
PVC is completely non-toxic and tasteless, and does not have any irritation to human skin or respiratory system. For those who are allergic to wood and paint, furniture or kitchenware packaged with PVC film is very suitable. By using PVC film as decorative film, people can largely avoid the use of MDF, particleboard, plywood and fiberboard, reduce the amount of wood used, and thus reduce damage to forests and even the environment.
The use of PVC once caused a lot of controversy in Western countries, and many people tried to replace PVC with various other materials. But it turns out that the quality of PVC is comparable to other alternatives, and it is less expensive than these materials.
Broad prospects
The PVC industry is developing rapidly all over the world and has broad prospects. All countries are optimistic about the potential of PVC and its benefits to the ecological environment. PVC is proving to the world that its role and status cannot be replaced by any other product with its superior and unique properties. Social development needs it, environmental protection needs it, and it is an inevitable trend of our human social civilization and progress.
