Polyurethane (PU) adhesives are adhesives containing urethane groups f-NHC00) and/or isocyanate groups (NCO) in the molecular chain. Polyurethane adhesives are widely used in the national economy because of their superior performance. They are one of the important varieties in synthetic adhesives. Huang Junxing et al. [7] studied modified polyvinyl chloride resin and polyurethane two kinds of adhesives and used them for bonding in the manufacture of PVC artificial leather. The two adhesives used diphenyl phthalate as a plasticizer. Add a certain amount of tackifying resin, use an appropriate amount of organic solvent, and add the appropriate amount of cross-linking agent. When the amount of dibutyl phthalate resin was increased to 3759, the adhesive had the highest peel strength, and the peel strength at this time was 250 N/25 cm. If you continue to increase the amount of plasticizers. The adhesive layer appeared unreliable, and the peel strength decreased. The addition of a tackifying resin to the vinyl chloride solution will greatly improve the lamination process of the sample. If chlorinated rosin is used together with 422# modified rosin resin, better process performance and peel strength can be obtained at the same time. However, it is not suitable to add various modified rosin resins in the polyurethane resin solution. The various isocyanate-based cross-linking agents have a certain effect on improving the peel strength of the vinyl chloride adhesive layer. In particular, Lekner, which has three functional groups, works best. Both of these adhesives can be used for the bonding of PVC artificial leather, but the adhesive layer of the perchloroethylene adhesive is relatively hard, and the polyurethane adhesive layer is relatively soft. The type of glue selected depends on the specific circumstances. Peng Huajun et al. discussed the synthetic process and application effect of PVC fencing electrostatic flocking adhesive. This adhesive uses a two-component polyurethane adhesive, component A is hydroxyl-terminated polyester polyurethane, and component 8 is isocyanate-based polyether polyurethane.
PVC flocking adhesive molecules contain urethane polar bonds (a NHC00) that are characteristic of them , and also contain a lot of ester bonds, ether bonds, urea bonds, and the like. It has good adhesion to many materials. He Yicai described the synthesis of a single-component solvent-based polyurethane adhesive for a metal sheet of PVC decorative film. Its use of high crystallinity polyester, isocyanate, chain extender and other raw materials, using vinyl chloride resin viscosity. The resulting product has a peel strength of 30 to 60N/2cm, a viscosity of 120 to 140s, and low irritation. All the mechanical properties of the glue have reached the same level of imported adhesives, and the baking and activation conditions have been reduced to a great extent, and the cost will be greatly reduced. It has been well received by many domestic PVC color plate manufacturers and can completely replace imported similar adhesives. Du Guanben introduced an adhesive based on aqueous polymer emulsion and isocyanate, which is particularly suitable for the compounding of PVC film and wood substrate. When the emulsion and curing agent ratio is l00:7 f mass ratio), the sizing amount is about 1009/m2, the hot pressing temperature is 85~90°C, the hot pressing cycle is 3 min, and the pressure is O. At 35 MPa, the normal peel strength of the PVC film after 72 h was 29 N/mm. This adhesive also has a high initial strength and can meet the processing requirements of "wood boring, milling and carving a PVC film". In addition, the adhesive is an aqueous polymer emulsion. No organic solvent contamination, safe use, wide application. Xu Dasheng and others used their own special polyester diols, 4,4'-diphenylmethane diisocyanate and chain extender 1,4-butanediol as the main raw materials to synthesize a production of PU-PVC composite leather. One-component adhesives. Compared with commonly used composite leather two-component polyurethane adhesives. The adhesive has a high adhesive strength. The application performance of these two adhesives is shown in Table 1. Dangerous people like to use MPU-20 polyurethane adhesive for PVC / steel and plastic wood composite. The peel strength of l800 of MPU-20 glue is ≥l. 96 kN/m, pH between 6 and 8, and the use temperature is 0.40°C. The glue has the advantages of quick construction, simple process, saving man-hours, low cost, strong adhesive force, normal temperature curing, insoluble, infusible, non-toxic and flame-retardant after the adhesive layer is cured. With its composite material used for cabin decoration of the cabin wall, the effect is better.