PVC molding characteristics:
1. Amorphous substances have low hygroscopicity and poor fluidity. In order to improve fluidity and prevent bubbles, plastics can be dried in advance. The gating system of the mold should be thick and short, the gate section should be large, and there should be no dead angle. The mold should be cooled and the surface should be chrome plated.
2. Because of its corrosiveness and fluidity, it is best to use special equipment and molds. All products must be added with different kinds and quantities of additives as required;
3. It is easy to decompose, and it is easier to decompose steel and copper when contacting at 200 degrees, and corrosive and irritating gases escape during decomposition. The molding temperature range is small;
4. When using the nozzle of the screw injection machine, the aperture should be large to prevent the dead angle from being delayed. If there is an insert, preheat it.
PVC (polyvinyl chloride) is a kind of material with flame retardancy, good chemical stability and low tensile cracking internal force. At the same time, its material characteristics include high strength, high rigidity and high hardness, and its working temperature ranges from-15 to 60 degrees, so it can be bonded and welded.
The main characteristics of PVC: strong corrosion resistance: the most suitable anti-corrosion equipment for chemical industry. Easy to process: cutting, welding and bending are extremely simple. High strength, high rigidity and high hardness; Good electrical insulation; Good chemical stability; Self-extinguishing; Low water absorption; Easy to bond and paint. Low price.
Application fields of PVC: acid test tower, seawater concentration tank, photo washing equipment, electroplating bath, battery box, electric meter board, audio seat cover, radio base plate, various electrical insulation boards, cement tank lining, mechanical windshield, exhaust pipe engineering, stationery, building materials, etc.
PU is polyurethane, and now many women's bags, clothes, sponges and high-grade artificial leather are made of PU. It is relatively safe to use, and now it has a tendency to expand.
Polyurethane, also known as polyurethane, is superior to PVC (commonly known as Xipi) in quality. Clothing manufacturers widely use this material to produce clothing, commonly known as imitation leather clothing. In addition, good bags mostly use imported PU leather.
PU leather is a kind of secondary leather whose reverse side is cowhide, and its surface is coated with a layer of PU resin, so it is also called coated cowhide. Its price is cheaper and its utilization rate is high. With the change of technology, it is also made into varieties of various grades, such as imported two-layer cowhide. Because of its unique technology, stable quality and novel varieties, it is regarded as high-grade leather, and its price and grade are no less than that of the first layer leather.
PU leather and real leather bags have their own characteristics. PU leather bag has beautiful appearance, easy care and low price. Leather is expensive, troublesome and durable.
In addition, many industrial workshops, such as steel structure workshops and cold storage workshops, use thermal insulation sandwich panels made of polyurethane foam, and polyurethane composite board with flame retardant has good thermal insulation and flame retardant effect. In addition, polyurethane materials are also widely used in building external wall insulation materials.
Extended data: identification
The difference between the two is actually very simple:
The elasticity of (1)pvc is worse than that of PU, and the resilience after stretching can be verified and compared. Pvc has some other substances added, so it is slippery; PU is more viscous and elastic.
(2) From the edge of PU, the base fabric of PU is generally fluffy, thick and soft to the touch; PVC base fabric is thin and difficult to handle.
(3) In the combustion test, PVC emits green smoke, while PU only emits black smoke; PU tastes much lighter than PVC.
(4) Put a small piece of cloth in gasoline for half an hour, and then take out the PVC artificial leather. It will become hard and brittle. If it is PU synthetic leather, it will not become hard and brittle.
(5) The surface texture of PU is more natural, true and full.
Reference: PU Polyurethane Material-Baidu Encyclopedia
PVC material-Baidu encyclopedia