Most people will call synthetic leather other than leather, such as PVC and PU leather, artificial leather or imitation leather. PVC and Pu are polyvinyl chloride (one of plastics), but the manufacturing processes of these two products are different.
In the manufacturing process of PVC leather, the plastic particles shall be melted and stirred into a paste, evenly coated on the T / C knitted fabric substrate according to the specified thickness, and then enter the foaming furnace for foaming, so that it has the softness that can adapt to the production of various products and different requirements. The surface treatment (dyeing, embossing, polishing, matting, grinding and fuzzing, etc.) shall be carried out at the same time when it is out of the furnace, mainly according to the specific product requirements.
The manufacturing process of PU leather is more complicated than that of PVC leather. Because the Pu base cloth is canvas PU material with good tensile strength, it can not only be coated on the base cloth, but also be included in the middle, so that the existence of the base cloth can not be seen outside. The physical properties of PU leather are better than those of PVC leather, with twists and turns resistance, good softness, high tensile strength and air permeability (PVC free). The pattern of PVC leather is hot pressed by a steel pattern roller; The pattern of PU leather is first hot pasted and pressed on the surface of semi-finished leather with a kind of pattern paper, and then separated the paper leather after cooling down for surface treatment. The price of PU leather is more than twice that of PVC leather, and the price of PU leather with special requirements is 2-3 times higher than that of PVC leather. Generally, the pattern paper required for PU leather can only be used for 4-5 times and will be scrapped; The service cycle of patterned roller is long, so the cost of PU leather is higher than that of PVC leather.
The scope of application of the two materials is also different. In terms of footwear, PVC leather is mostly used in lining or non weight bearing parts, or in the manufacture of children's shoes; PU leather can be applied to the fabric of shoes or parts bearing weight. In terms of bags, PVC leather is more suitable. This is because the items in the bag are different from the feet in shoes and will not emit heat; No need to bear personal weight.
It is easy to distinguish between Pu and PVC. From the corners, the bottom cloth of Pu is much thicker than PVC, and there are also differences in hand feeling. Pu feels softer; PVC feels harder; You can also burn it with fire. The taste of Pu is much lighter than that of PVC.
The top layer of VC is paint, the main component in the middle is polyvinyl chloride, and the bottom layer is back coated adhesive.
PU, commonly known as synthetic leather, has a light proportion. The lines of Pu are all paper lines, which is a process of coating Pu slurry on the release paper with lines, cooling and shaping, and then stripping the paper, so as to leave the paper lines on the Pu layer.
Pu can also be processed and embossed. In terms of production technology, there are two methods: wet method and dry method. The two are very easy to distinguish. Wet method is generally thicker, because there is a layer of base (low foaming layer) between the surface layer and the bottom cloth, while the dry method has no base and is directly coated on the bottom of the cloth, so it is thin and the lines are deformed.
Wet PU has a wide range of uses, such as bags, handbags, shoes, balls, stationery, sofas and so on, while the dry principle is mainly used in packaging and clothing.
Identification method:
1. PU feels softer than PVC, with good quality and toughness. It is generally used as fabric and can withstand relatively large tensile force;
2. Pu is more expensive than PVC;
3. PVC can be torn by force, but Pu cannot;
4. PVC bottom cloth is generally thin and thin; PVC has more water needle cloth bottom and sweat clothes cloth bottom, while Pu cloth bottom has higher quality; The base of PVC leather is generally textile cloth and knitted cloth, and the base of PU leather is non-woven cloth;
5. If you burn with fire, the taste of Pu is relatively light, and PVC will turn black and stink.
6. The specific gravity of PVC is larger than that of PU.
7. PVC has deep lines and obvious foaming layer in the middle.
Pu is divided from grain, including mirror Pu, sheep Pu, nappapu, two-color Pu, soft wood Pu, metal Pu, Helen Pu, litchi Pu, pig skin Pu, R61 Pu, crocodile Pu, fish scale Pu, soft grain, etc. Mirror Pu is characterized by bright surface, wrinkled mirror Pu, crystal mirror Pu, film coated mirror Pu, etc. The lines of Nappa, KMF, metal and R61 Pu are relatively similar, which can only be distinguished by the naked eye when they are very fine, mainly due to the difference of lines and patterns. The surface of the cloth is the same color as PU. Look carefully at the R61 pattern, there are some small holes; Sheep grain is a continuous small hole; The lines of Nappa are regular and obvious; The rest is the Helen pattern of KMF, which has no fixed rules; The lines of soft PU are very shallow and light. There is also a kind of elastic Pu, which has obvious elasticity. The surface of semi Pu is Pu and the bottom cloth is PVC. In fact, it belongs to PVC and can be torn by hand. SEMIPU, also known as imitation PU.
1. Artificial leather is mainly divided into imitation leather (or rubber) and high-grade PU. Imitation leather or rubber is the general name of artificial materials such as PVC and PU. It is made of foamed or coated PVC and PU with different formulas on the basis of textile cloth or non-woven cloth. It is characterized by a wide variety, good waterproof performance, neat edge, high utilization rate and relatively cheap price. High grade Pu, the surface technology and the fiber structure of the base material, almost achieve the effect of leather, and its price is comparable to that of domestic first layer leather.
In the manufacturing process of PVC leather, the plastic particles shall be melted and stirred into a paste, evenly coated on the T / C knitted fabric substrate according to the specified thickness, and then enter the foaming furnace for foaming, so that it has the softness that can adapt to the production of various products and different requirements. The surface treatment (dyeing, embossing, polishing, matting, grinding and fuzzing, etc.) shall be carried out at the same time when it is out of the furnace, mainly according to the specific product requirements.
The manufacturing process of PU leather is more complicated than that of PVC leather. Because the Pu base cloth is canvas PU material with good tensile strength, it can not only be coated on the base cloth, but also be included in the middle, so that the existence of the base cloth can not be seen outside. The physical properties of PU leather are better than those of PVC leather, with twists and turns resistance, good softness, high tensile strength and air permeability (PVC free). The pattern of PVC leather is hot pressed by a steel pattern roller; The pattern of PU leather is first hot pasted and pressed on the surface of semi-finished leather with a kind of pattern paper, and then separated the paper leather after cooling down for surface treatment. The price of PU leather is more than twice that of PVC leather, and the price of PU leather with special requirements is 2-3 times higher than that of PVC leather. Generally, the pattern paper required for PU leather can only be used for 4-5 times and will be scrapped; The service cycle of patterned roller is long, so the cost of PU leather is higher than that of PVC leather.
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 floor, ceiling and leather surface, but because soft PVC contains softener (which is also the difference between soft PVC and hard PVC), it is easy to become brittle and difficult to preserve, so its scope of use is limited. Hard PVC does not contain softener, so it has good flexibility, easy to form, not easy to crisp, non-toxic, pollution-free and long storage time. Therefore, it has great development and application value. Hereinafter referred to as PVC. The essence of PVC is a kind of vacuum blister film, which is used for the surface packaging of various panels, so it is also known as decorative film and adhesive film. It is used in building materials, packaging, medicine and many other industries. Among them, the building materials industry accounts for the largest proportion, accounting for 60%, followed by the packaging industry, and several other industries with small-scale application.
2. Synthetic leather (semi PU leather)
Synthetic leather is a good substitute for leather, which is used to make leather jackets in winter. However, synthetic leather is processed by TPU (polyurethane elastomer). The price of TPU is very expensive, so many domestic manufacturers use PVC to partially replace it. They do this: PVC (artificial leather) is coated on the cloth base first, and then TPU is coated. In this way, the price can be greatly reduced, but the plasticizer in PVC will migrate out in less than a year, resulting in the hardening and brittleness of synthetic leather (actually artificial leather). Therefore, some customers buy new leather jackets, which are brittle and cracked in less than a year. In fact, the factories producing synthetic leather call them semi synthetic leather or semi PU leather.
Semi PU leather can be identified by a very simple method, that is, heating the copper wire in the fire until the color of the fire is red (no green), and the copper wire will also burn red in the fire. Put the copper wire on the synthetic leather immediately, and the synthetic leather will melt on the copper wire. Finally, put the copper wire on the fire again. If the fire is green at this time, it will prove that there is PVC, which is semi PU leather. If the fire is red at this time, it will prove that it is PU leather, This method is a simple method and can be used for general identification
3. Characteristics and differences between PVC and PU
PVC is the first substitute invented for leather fabric. It is made of PVC plus plasticizer and other additives calendered and compounded on the cloth. It has the advantages of low price, rich colors and various patterns, and the disadvantage is that it is easy to harden and brittle.
PU synthetic leather is used to replace PVC artificial leather, and its price is higher than PVC artificial leather. In terms of chemical structure, it is closer to leather fabric. It does not use plasticizer to achieve soft properties, so it will not harden and become brittle. At the same time, it has the advantages of rich colors and various patterns, and the price is cheaper than leather fabric, so it is welcomed by consumers.
It is easy to distinguish between Pu and PVC. From the corners, the bottom cloth of Pu is much thicker than PVC, and there are also differences in hand feeling. Pu feels softer; PVC feels harder; You can also burn it with fire. The taste of Pu is much lighter than that of PVC.
PU is polyurethane, and PU skin is the skin of polyurethane Now clothing manufacturers widely use this material to produce clothing, commonly known as imitation leather clothing PU is the abbreviation of English employment urethane and the Chinese name of chemical polyurethane. Its quality is also good or bad. Good bags mostly use imported PU skin;
Pu matching leather is generally the second layer of leather material of cow leather on the reverse side. A layer of PU resin is coated on the surface, so it is also called film coated cow leather. Its price is cheap 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 leather. Due to the characteristics of unique technology, stable quality and novel varieties, it is the current high-grade leather, and the price and grade are no less than the first layer leather.
PU leather and real leather bags have their own characteristics. PU leather bags have beautiful appearance, easy care and low price, but they are not wear-resistant and easy to break; Leather is expensive and troublesome, but it is durable.
