Polyurethane synthetic leather
DATE：2022/6/17 8:40:54 / READ： / SOURCE：This station
Polyurethane synthetic leather
Because polyurethane resin has excellent physical and chemical properties, and according to the different requirements of use, polyurethane resin can produce a product with good strength, good warmth and humidity, porous air permeability, oil resistance, cold resistance, folding resistance and wear resistance. Therefore, polyurethane synthetic leather has developed rapidly. Polyurethane synthetic leather is not only used in flexible containers, pipelines and conveyor belts for daily use. In addition, in heavy industry, polyurethane synthetic leather can be compared with natural leather in terms of physical properties, moisture permeability, breathability or respiration. Polyurethane synthetic leather is an ideal synthetic leather with synthetic fiber non cloth as the base material, and the ply is composed of microporous polyurethane elastomer. Its thickness is three times that of ordinary artificial leather. Coating compound production line www.handern com1. raw materials
Polyurethane synthetic leather consists of four parts: substrate, base sheet, micro porous layer and surface decorative layer. The raw material requirements and composition of each part are also different, which are described as follows. Coating compound production line www.handern com
① Base. Polyurethane leather base materials are all made of synthetic fiber non-woven fabrics. ② Layer sheet. After the above substrate is impregnated with polyurethane resin solution, there is resin between the three-dimensional structures of synthetic fiber, and then the resin is solidified with non solvent such as water. The solvent is extracted by water, resulting in the porous elastomer. At this time, the porous elastomer is used as the adhesive of the fiber to ensure the cold resistance, strength, toughness and wear resistance of the substrate. As the three-dimensional structure of synthetic fiber, it is the adhesive of non-woven fabric substrate. Generally, PTMG reacts with pure 24 toluene diisocyanate to synthesize prepolymer containing hydroxyl at the end, and then reacts with MDI to form prepolymer containing isocyanate at the end. After being treated with chain extender, polyurethane polyurea resin liquid is generated. ③ Micro porous layer. The micro porous layer compound is the key to the composition of synthetic leather, and it is also the basis to ensure the properties of synthetic leather. The polyurethane resin used for micro porous layer is made of polyester polyurethane or polyether polyurethane (linear polymer with relative molecular weight of about 5000~300000) containing hydroxyl at the end in the presence of prepolymer curing agent containing isocyanate at the end. The formula of polyurethane resin is as follows
2. production process coating compound production line www.handern com
On the one hand, polyurethane prepolymer and other coatings are applied on the stripping paper in advance and dried to form a microporous adhesive layer. On the other hand, one side of the synthetic fiber substrate is also coated and scraped with a coating composed of polyurethane prepolymer. Before curing, it is rolled and bonded with a pressing roller, then dried to remove the solvent, rolled and placed in the curing room for curing before stripping the face paper. The production process of polyurethane synthetic leather is shown in Figure 5-17. Gluing scraper base cloth roll bonding dryer e drum to curing room release paper dryer
Figure 5-17 production process flow of polyurethane synthetic leather
① Apply the polyurethane prepolymer onto the stripping paper. The stripping paper is coated with silicone resin so that it does not adhere to the polyurethane adhesive layer. Coating compound production line www.handern com
② The coated scraping material is continuously passed through the drying curing oven and heated to 80 ℃ with an infrared lamp to remove the solvent.
③ The cloth base with materials is pressed together by two rollers, and then sent to the foaming box. The temperature in the box is 140 ℃, the foaming agent is decomposed within 5min, and the prepolymer is crosslinked and solidified to form
Microporous, polyurethane adhesive layer
④ Send it to the curing room for curing at 50 ℃ for 12h. ⑤ After cooling, peel off the surface paper to obtain synthetic leather
The performance of polyurethane synthetic leather is determined by the four parts that make up the synthetic leather, that is, it depends on the size of the synthetic fiber and the density of the fabric of the substrate, and also depends on the thickness, material and composition of the polyurethane micro porous layer, as well as the material of the surface decorative layer. In a word, there are many factors that affect the properties of polyurethane synthetic leather, but the key factor is the properties of the compound itself. Coating compound production line www.handern com
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