Automotive high-strength polyurethane self-adhesive glue and preparation method thereof

Abstract

The invention discloses high-strength polyurethane self-adhesive glue for a vehicle and a preparation method of the high-strength polyurethane self-adhesive glue. The high-strength polyurethane self-adhesive glue for the vehicle comprises first polyurethane resin, second polyurethane resin, a plasticizer, a modified adhesion accelerant, filler, carbon black, a first catalyst and a water removal agent, wherein the first polyurethane resin is prepared from polyoxypropylene triol and diisocyanate through a reaction; the second polyurethane resin is prepared from polyether glycol and modified isocyanate through a reaction, and the modified isocyanate is prepared from hydroxyethyl methylacrylate and triisocyanate through a drop-by-drop reaction; the modified adhesion promoter is prepared by reacting hydroxyl-containing GMA modified silane with triisocyanate drop by drop, and the hydroxyl-containing GMA modified silane is prepared by carrying out ring-opening reaction on glycidyl methacrylate and secondary amino silane; the polyurethane self-adhesive glue has the characteristics of high bonding strength, excellent mechanical properties and environmental protection, and can realize a self-adhesive effect without a primer and an activator.

Description

Technical Field

[0001] The invention belongs to the technical field of polyurethane adhesives, and in particular relates to a high-strength polyurethane self-adhesive for vehicles and a preparation method thereof. Background Art

[0002] With the rapid development of the modern transportation industry, the environmental and safety requirements for vehicle components in the automotive, bus, and rail transit sectors are increasing. The bonding and sealing of windshields and side windows are critical factors affecting the overall structural strength, sealing performance, and durability of a vehicle. Currently, high-strength polyurethane adhesives (shear strength ≥ 4.5 MPa) are widely used for elastic bonding between glass and sheet metal due to their excellent bonding strength, weather resistance, and flexibility. However, due to the strong cohesive force of polyurethane adhesives, they have difficulty fully soaking into the ceramic glaze layer or sheet metal on the glass surface, resulting in insufficient bonding strength at the bonding interface and affecting long-term reliability.

[0003] Currently, OEMs require pre-treatment with an activator and primer for high-strength polyurethane adhesives to meet vehicle assembly requirements. However, this process has numerous drawbacks: First, the activator and primer must be applied on-site before application, and the solvent must be allowed to evaporate completely (typically taking over five minutes). In cold winter conditions, the solvent evaporates more slowly, requiring longer process times, extending vehicle assembly cycles and impacting production efficiency. Second, activators and primers typically contain large amounts of organic solvents, which release high concentrations of volatile organic compounds (VOCs) during application and evaporation. This not only pollutes the workshop environment but can also pose health risks to operators, contradicting industry trends toward green manufacturing. Furthermore, the process involves multiple pre-treatment steps, increasing operational complexity and requiring high worker proficiency. Uneven application or inadequate solvent evaporation can lead to unstable bonding quality.

[0004] Therefore, there is an urgent need for a high-strength polyurethane self-adhesive for automobiles and a preparation method thereof to solve the deficiencies of the existing technical problems. Summary of the Invention

[0005] In view of the above problems, the purpose of the present invention is to provide a high-strength polyurethane self-adhesive for automobiles and a preparation method thereof. The polyurethane self-adhesive has the characteristics of high bonding strength, excellent mechanical properties, and is environmentally friendly. It is very suitable for bonding and sealing windshields and side windows of automobiles, rail vehicles, etc., reducing the number of process steps in the main engine factory and reducing the VOC content in the workshop, thereby preventing workers from being affected by the volatilization of solvents in products such as primers.

[0006] To achieve the above object, the present application provides a high-strength polyurethane self-adhesive for vehicles, which is prepared from 20-30 parts by mass of a first polyurethane resin, 5-10 parts by mass of a second polyurethane resin, 20-30 parts by mass of a plasticizer, 5-10 parts by mass of a modified adhesion promoter, 10-20 parts by mass of a filler, 18-26 parts by mass of carbon black, 0.02-0.10 parts by mass of a first catalyst, and 0.2-1.0 parts by mass of a water-removing agent; wherein the first polyurethane resin is prepared from polyoxypropylene triol and a first cyanate ester; the second polyurethane resin is prepared from polyether diol and a modified isocyanate ester, which is prepared from dropwise reaction of hydroxyethyl methacrylate and a second cyanate ester; the modified adhesion promoter is prepared from dropwise reaction of a GMA-modified silane containing a hydroxyl group and a third cyanate ester, which is prepared from ring-opening reaction of glycidyl methacrylate and a secondary amine-based silane; the first cyanate ester is diisocyanate, and the second and third cyanate esters are triisocyanate.

[0007] Compared with the prior art, the high-strength polyurethane self-adhesive for vehicles has the following effects: 1. The present application introduces acrylic ester compound HEMA into the second polyurethane resin and introduces acrylic ester compound GMA into the modified adhesion promoter, which significantly improves the interface contact effect of the adhesive with the glass, sheet metal and other substrates by using the excellent migration and wetting properties of the acrylic ester compound; meanwhile, the ester group (-COO) of the acrylic ester can form a large number of hydrogen bonds with the surface of the substrate, producing strong adsorption; and the siloxane group (-Si-O-R) in the modified adhesion promoter forms a chemical bond (Si-O-Si) with the hydroxyl group on the surface of the substrate, and the acrylic ester double bond in the second polyurethane resin can produce physical anchoring effect with the surface of the substrate during the curing process, further enhancing the interface bonding force, which fundamentally guarantees the high adhesion strength of the polyurethane self-adhesive.

[0008] 2. The present application grafts the acrylate compound HEMA to the side chain of the polyurethane resin through triisocyanate, while the triisocyanate molecule retains two NCO groups to maintain crosslinking activity, which realizes functional modification without affecting the normal crosslinking and curing of the polyurethane; similarly, GMA is grafted into the modified adhesion promoter through triisocyanate, while the triisocyanate molecule retains two NCO active groups and GMA is firmly fixed on the molecular chain through stable chemical bonding and cannot migrate and lose, GMA has good compatibility with the HEMA structure in the second polyurethane resin, thereby improving the migration ability of silane in the modified adhesion promoter to the surface of the substrate and the adhesion and attachment. Therefore, the present application introduces multiple crosslinking points through triisocyanate to greatly improve the crosslinking density of the polyurethane system, thereby significantly enhancing the mechanical strength of the polyurethane adhesive; at the same time, the stable existing acrylate compound effectively improves the durability and weather resistance of the adhesive through synergistic effect, so that it can maintain durable bonding strength under various harsh environmental conditions.

[0009] 3. The polyurethane adhesive of the present application does not contain solvent, can realize the effect of self-adhesion without primer, does not need to use solvent-containing activator and primer in the application process, improves the work efficiency, and is more in line with the requirements of modern industry for environmental protection.

[0010] Further, the first cyanate of the present application is selected from at least one of toluene diisocyanate (TDI), diphenylmethane diisocyanate (MDI), hexamethylene diisocyanate (HDI), isophorone diisocyanate (IPDI), naphthalene diisocyanate (NDI), and xylylene diisocyanate (XDI).

[0011] Further, the number average molecular weight of the polyoxypropylene triol of the present application is 5000-8000, and the number average molecular weight of the polyether diol is 2000-4000. Specifically, the polyether diol can be but is not limited to polyoxypropylene diol.

[0012] Further, the second cyanate and the third cyanate of the present application are each independently selected from at least one of hexamethylene diisocyanate trimer (HDI trimer), isophorone diisocyanate trimer (IPDI trimer), toluene diisocyanate trimer (TDI trimer), thiophosphoric acid triphenyl triisocyanate, and triphenylmethane triisocyanate.

[0013] Further, the plasticizer of the present application is selected from at least one of phthalate, alkyl sulfonic acid phenyl ester, adipate, epoxy ester, and phosphate ester.

[0014] Further, the filler of the present application is selected from at least one of heavy calcium carbonate, modified calcium carbonate, calcined kaolin, talc powder, and dolomite powder.

[0015] Furthermore, the first catalyst of the present invention is at least one selected from the group consisting of organotin, organobismuth, organozinc and organoamine.

[0016] Furthermore, the secondary aminosilane of the present invention is at least one selected from N-phenyl-3-aminopropyltrimethoxysilane, N-n-butyl-3-aminopropyltrimethoxysilane, N-n-butyl-3-aminopropyltriethoxysilane, bis(3-methoxysilylpropyl)amine, and bis(3-ethoxysilylpropyl)amine.

[0017] Furthermore, the water removing agent of the present invention is p-toluenesulfonyl isocyanate.

[0018] Furthermore, the preparation of the first polyurethane resin of the present invention includes placing polyoxypropylene triol, a first cyanate ester, and a second catalyst in a reactor and allowing the reaction to proceed at a constant temperature until the NCO concentration reaches a theoretical value, thereby obtaining the first polyurethane resin. Specifically, the molar ratio of the isocyanate functional groups in the first cyanate ester to the hydroxyl functional groups in the polyoxypropylene triol of the present invention is 2.1-2.5:1, such as, but not limited to, 2.1:1, 2.2:1, 2.3:1, 2.4:1, or 2.5:1. The second catalyst may be, but not limited to, an organotin catalyst, such as, but not limited to, stannous octoate or dibutyltin dilaurate. Specifically, the mass of the second catalyst may be 0.05-0.50% of the combined mass of the polyoxypropylene triol and the first cyanate ester, such as, but not limited to, 0.05%, 0.1%, 0.15%, 0.2%, 0.25%, 0.3%, 0.36%, 0.42%, 0.48%, or 0.5%. The temperature of the heat preservation reaction during the preparation process of the first polyurethane resin is 60~70℃; the temperature of the heat preservation reaction can be, but is not limited to, 60℃, 62℃, 64℃, 65℃, 66℃, 68℃, or 70℃; the temperature of the heat preservation reaction is preferably 65℃.

[0019] Furthermore, the preparation of the second polyurethane resin of the present invention includes placing a polyether diol, a modified isocyanate, and a third catalyst in a reactor and allowing the reaction to proceed at this temperature until the NCO concentration reaches the theoretical value, thereby obtaining the second polyurethane resin. Specifically, the molar ratio of the isocyanate functional groups in the modified isocyanate to the hydroxyl functional groups in the polyether diol is 1.4-1.8:1; for example, but not limited to, 1.4:1, 1.5:1, 1.6:1, 1.7:1, or 1.8:1. The third catalyst can be an organotin catalyst, such as, but not limited to, stannous octoate or dibutyltin dilaurate. Specifically, the mass of the third catalyst accounts for 0.05-0.50% of the combined mass of the polyether diol and the modified isocyanate; for example, but not limited to, 0.05%, 0.1%, 0.15%, 0.2%, 0.25%, 0.3%, 0.36%, 0.42%, 0.48%, or 0.5%. Specifically, the temperature of the insulation reaction during the preparation of the second polyurethane resin is 60-70°C. For example, the temperature of the insulation reaction can be, but is not limited to, 60°C, 62°C, 64°C, 65°C, 66°C, 68°C, or 70°C; the temperature of the insulation reaction is preferably 65°C.

[0020] Furthermore, the preparation of the modified isocyanate of the present invention includes placing a second cyanate and a first solvent in a reactor, adding hydroxyethyl methacrylate dropwise, allowing the reaction to proceed to the theoretical NCO value, and performing a first post-treatment to obtain the modified isocyanate. Specifically, the first solvent may be, but is not limited to, ethyl acetate. Specifically, the molar ratio of the second cyanate to hydroxyethyl methacrylate (HEMA) is 1:0.8-1.2; for example, the molar ratio may be, but is not limited to, 1:0.8, 1:0.9, 1:1, 1:1.1, or 1:1.2. Specifically, the addition rate of the hydroxyethyl methacrylate is 2-4 g / s, such as, but not limited to, 2 g / s, 3 g / s, or 4 g / s. The temperature of the reaction during the preparation of the modified isocyanate is 60-70°C. For example, the reaction temperature may be, but is not limited to, 60°C, 62°C, 64°C, 65°C, 66°C, 68°C, or 70°C; the reaction temperature is preferably 65°C. Specifically, the first post-treatment is to perform reduced pressure distillation on the reaction product to remove the first solvent.

[0021] Furthermore, the preparation of the modified adhesion promoter of the present invention includes: placing a secondary aminosilane, glycidyl methacrylate, and a second solvent in a reactor, incubating the reaction until the infrared absorption peak of the epoxy group disappears to obtain a hydroxyl-containing GMA-modified silane; then, dropwise adding the hydroxyl-containing GMA-modified silane to a third cyanate ester, incubating the reaction until the NCO concentration reaches the theoretical value; and performing a second post-treatment to obtain the modified adhesion promoter. Specifically, the molar ratio of the secondary aminosilane to glycidyl methacrylate (GMA) is 1:1. Specifically, the secondary aminosilane, glycidyl methacrylate, and ethyl acetate are placed in a reactor and incubated at 70-80°C until the infrared absorption peak of the epoxy group disappears to obtain the hydroxyl-containing GMA-modified silane. The incubation temperature can be, but is not limited to, 70°C, 73°C, 75°C, 78°C, or 80°C; the incubation temperature is preferably 75°C. Specifically, a hydroxyl-containing GMA-modified silane is added dropwise to the third cyanate ester at a dropwise rate of 2-4 g / s, and the reaction is carried out at 60-70°C until the NCO reaches the theoretical value. The dropwise rate of the hydroxyl-containing GMA-modified silane can be, but is not limited to, 2 g / s, 2.5 g / s, 3 g / s, 3.5 g / s, 3.8 g / s, or 4 g / s. The specific temperature of the heat treatment can be, but is not limited to, 60°C, 62°C, 64°C, 65°C, 66°C, 68°C, or 70°C, with the heat treatment temperature preferably being 65°C. Specifically, the second solvent can be, but is not limited to, ethyl acetate.

[0022] Specifically, the second post-treatment is to subject the reaction product to reduced pressure distillation to remove the second solvent. Specifically, the molar ratio of the hydroxyl-containing GMA-modified silane to the third cyanate ester is 0.8 to 1.2:1, and the molar ratio can be, but is not limited to, 0.8:1, 0.9:1, 1:1, 1.1:1, or 1.2:1.

[0023] Furthermore, the water content of the polyoxypropylene triol and the polyether diol of the present invention is less than 0.03%. Specifically, they can be subjected to reduced pressure distillation at 100-110° C. to a water content of less than 0.03%, wherein the vacuum degree during the reduced pressure distillation process is ≤-0.098 MPa.

[0024] Accordingly, a second aspect of the present invention provides a method for preparing a high-strength polyurethane self-adhesive adhesive for vehicles, comprising the steps of placing a formulated amount of a first polyurethane resin, a second polyurethane resin, a plasticizer, a modified adhesion promoter, a filler, carbon black, a first catalyst, and a water scavenger in a closed mixer, vacuuming and stirring until a uniform paste is formed to obtain the high-strength polyurethane self-adhesive adhesive for vehicles.

[0025] Furthermore, the present invention comprises placing a first polyurethane resin, a second polyurethane resin, a plasticizer, a modified adhesion promoter, a filler, carbon black, a first catalyst, and a water scavenger in a closed mixer and stirring under vacuum for 30 to 180 minutes until a uniform paste is formed to obtain a high-strength polyurethane self-adhesive adhesive for automobiles. Specifically, the stirring time can be, but is not limited to, 30 minutes, 60 minutes, 90 minutes, 120 minutes, 150 minutes, or 180 minutes, with 60 minutes being preferred. The vacuum degree of the evacuation is ≤ -0.098 MPa. DETAILED DESCRIPTION

[0026] To better illustrate the purpose, technical solutions and beneficial effects of the present invention, the present invention will be further described below in conjunction with specific examples. It should be noted that the following implementation method is a further explanation of the present invention and should not be used as a limitation of the present invention. The raw materials used in the following examples and comparative examples are all industrial grade. Please refer to Table 1 for the source of the raw materials.

[0027] Table 1

[0028] Example 1 This embodiment provides a high-strength polyurethane self-adhesive for automobiles. The raw materials for preparation include, by weight, 30 parts of a first polyurethane resin, 5 parts of a second polyurethane resin, 20 parts of a plasticizer, 6 parts of a modified adhesion promoter, 15.65 parts of a filler, 23 parts of carbon black, 0.05 parts of a first catalyst, and 0.3 parts of a water scavenger. The plasticizer is diisononyl phthalate, the filler is heavy calcium carbonate, the carbon black is M570 carbon black, and the first catalyst is dibutyltin dilaurate. The water scavenger is p-toluenesulfonyl isocyanate. The preparation of the first polyurethane resin includes: placing 100 parts by mass of polyoxypropylene triol (number average molecular weight of 5000, moisture ≤300 ppm) in a reactor, heating to 65° C., adding 17.25 parts of MDI and 0.058 parts of dibutyltin dilaurate, and maintaining the temperature to react until the isocyanate content is detected to be 2.79%, thereby obtaining the first polyurethane resin; The second polyurethane resin is prepared by placing 100 parts by mass of polyoxypropylene glycol (number average molecular weight of 2000, moisture content ≤300 ppm) in a reactor, heating the reactor to 65° C., adding 50.78 parts of modified isocyanate and 0.075 parts of dibutyltin dilaurate, and maintaining the temperature to react until the isocyanate content is detected to be 1.67%, thereby obtaining the second polyurethane resin. The preparation of the modified isocyanate comprises: placing 504.6 parts by mass of HDI trimer and 634.74 parts of ethyl acetate in a reactor, heating the reactor to 65° C., then adding 130.14 parts of HEMA dropwise at a rate of 3 g / s, maintaining the temperature and reacting until the isocyanate content is 6.62% as determined by a test, and removing the ethyl acetate by vacuum distillation to obtain the modified isocyanate; The preparation of the modified adhesion promoter includes: placing 255.38 parts of N-phenyl-3-aminopropyltrimethoxysilane, 142.15 parts of GMA, and 397.53 parts of ethyl acetate in a reactor, heating the temperature to 75°C, and maintaining the temperature for reaction until the infrared absorption peak of the epoxy group disappears to obtain a hydroxyl-containing GMA-modified silane; then, adding the hydroxyl-containing GMA-modified silane dropwise at a rate of 3 g / s to a reactor containing 504.6 parts of HDI trimer; maintaining the temperature for reaction at 65°C until the isocyanate content is detected to be 6.46%, and removing the ethyl acetate by reduced pressure distillation to obtain the modified adhesion promoter.

[0029] This embodiment also provides a method for preparing a high-strength polyurethane self-adhesive for vehicles, comprising the following steps: The first polyurethane resin, the second polyurethane resin, the plasticizer, the modified adhesion promoter, the filler, the carbon black, the first catalyst, and the water scavenger in the formulated amount are placed in a closed mixer and vacuumed to -0.098 MPa, and stirred for 60 minutes to obtain a uniform paste-like high-strength polyurethane self-adhesive for automobiles.

[0030] Example 2 This embodiment provides a high-strength polyurethane self-adhesive for automobiles. The raw materials for preparation include, by weight, 25 parts of a first polyurethane resin, 10 parts of a second polyurethane resin, 20 parts of a plasticizer, 6 parts of a modified adhesion promoter, 15.65 parts of a filler, 23 parts of carbon black, 0.05 parts of a first catalyst, and 0.3 parts of a water scavenger. The plasticizer is diisononyl phthalate, the filler is heavy calcium carbonate, the carbon black is M570 carbon black, and the first catalyst is dibutyltin dilaurate. The water scavenger is p-toluenesulfonyl isocyanate. The preparation of the first polyurethane resin includes: placing 100 parts by mass of polyoxypropylene triol (number average molecular weight of 5000, moisture ≤300 ppm) in a reactor, heating to 65° C., adding 17.25 parts of MDI and 0.058 parts of dibutyltin dilaurate, and maintaining the temperature to react until the isocyanate content is detected to be 2.79%, thereby obtaining the first polyurethane resin; The second polyurethane resin is prepared by placing 100 parts by mass of polyoxypropylene glycol (number average molecular weight of 2000, moisture content ≤300 ppm) in a reactor, heating the reactor to 65° C., adding 63.77 parts of modified isocyanate and 0.082 parts of dibutyltin dilaurate, and maintaining the temperature to react until the isocyanate content is detected to be 1.54%, thereby obtaining the second polyurethane resin. The modified isocyanate is prepared by placing 666.96 parts by mass of IPDI trimer and 797.1 parts of ethyl acetate in a reactor, heating the reactor to 65° C., then adding 130.14 parts of HEMA dropwise at a rate of 3 g / s, maintaining the temperature and reacting until the isocyanate content is 5.27% as determined by a test, and removing the ethyl acetate by vacuum distillation to obtain the modified isocyanate. The preparation of the modified adhesion promoter includes: placing 255.38 parts of N-phenyl-3-aminopropyltrimethoxysilane, 142.15 parts of GMA, and 397.53 parts of ethyl acetate in a reactor, heating the temperature to 75°C, and maintaining the temperature for reaction until the infrared absorption peak of the epoxy group disappears to obtain a hydroxyl-containing GMA-modified silane; then, adding the hydroxyl-containing GMA-modified silane dropwise at a rate of 3 g / s to a reactor containing 504.6 parts of HDI trimer; maintaining the temperature for reaction at 65°C until the isocyanate content is detected to be 6.46%, and removing the ethyl acetate by reduced pressure distillation to obtain the modified adhesion promoter.

[0031] This embodiment also provides a method for preparing a high-strength polyurethane self-adhesive for vehicles, comprising the following steps: The first polyurethane resin, the second polyurethane resin, the plasticizer, the modified adhesion promoter, the filler, the carbon black, the first catalyst, and the water scavenger in the formulated amount are placed in a closed mixer and vacuumed to -0.098 MPa, and stirred for 60 minutes to obtain a uniform paste-like high-strength polyurethane self-adhesive for automobiles.

[0032] Example 3 This embodiment provides a high-strength polyurethane self-adhesive for automobiles. The raw materials for preparation include, by weight, 20 parts of a first polyurethane resin, 5 parts of a second polyurethane resin, 25 parts of a plasticizer, 10 parts of a modified adhesion promoter, 15.65 parts of a filler, 24 parts of carbon black, 0.05 parts of a first catalyst, and 0.3 parts of a water scavenger. The plasticizer is diisononyl phthalate, the filler is heavy calcium carbonate, the carbon black is M570 carbon black, and the first catalyst is dibutyltin dilaurate. The water scavenger is p-toluenesulfonyl isocyanate. The preparation of the first polyurethane resin includes: placing 100 parts by mass of polyoxypropylene triol (number average molecular weight of 5000, moisture ≤300 ppm) in a reactor, heating to 65° C., adding 17.25 parts of MDI and 0.058 parts of dibutyltin dilaurate, and maintaining the temperature to react until the isocyanate content is detected to be 2.79%, thereby obtaining the first polyurethane resin; The second polyurethane resin is prepared by placing 100 parts by mass of polyoxypropylene glycol (number average molecular weight of 2000, moisture content ≤300 ppm) in a reactor, heating the reactor to 65° C., adding 50.78 parts of modified isocyanate and 0.075 parts of dibutyltin dilaurate, and maintaining the temperature to react until the isocyanate content is detected to be 1.67%, thereby obtaining the second polyurethane resin. The preparation of the modified isocyanate comprises: placing 504.6 parts by mass of HDI trimer and 634.74 parts of ethyl acetate in a reactor, heating the reactor to 65° C., then adding 130.14 parts of HEMA dropwise at a rate of 2 g / s, maintaining the temperature and reacting until the isocyanate content is 6.62% as determined by a test, and removing the ethyl acetate by vacuum distillation to obtain the modified isocyanate; The preparation of the modified adhesion promoter includes: placing 235.39 parts of N-n-butyl-3-aminopropyltrimethoxysilane, 142.15 parts of GMA, and 377.54 parts of ethyl acetate in a reactor, heating the temperature to 75°C, and maintaining the temperature for reaction until the infrared absorption peak of the epoxy group disappears to obtain a hydroxyl-containing GMA-modified silane; then, adding the hydroxyl-containing GMA-modified silane dropwise at a rate of 3 g / s to a reactor containing 504.6 parts of HDI trimer; maintaining the temperature for reaction at 65°C until the isocyanate content is detected to be 6.67%, and removing the ethyl acetate by reduced pressure distillation to obtain the modified adhesion promoter.

[0033] This embodiment also provides a method for preparing a high-strength polyurethane self-adhesive for vehicles, comprising the following steps: The first polyurethane resin, the second polyurethane resin, the plasticizer, the modified adhesion promoter, the filler, the carbon black, the first catalyst, and the water scavenger in the formulated amount are placed in a closed mixer and vacuumed to -0.098 MPa, and stirred for 60 minutes to obtain a uniform paste-like high-strength polyurethane self-adhesive for automobiles.

[0034] Example 4 This embodiment provides a high-strength polyurethane self-adhesive for automobiles. The raw materials for preparation include, by weight, 25 parts of a first polyurethane resin, 8 parts of a second polyurethane resin, 22.65 parts of a plasticizer, 6 parts of a modified adhesion promoter, 15 parts of a filler, 23 parts of carbon black, 0.05 parts of a first catalyst, and 0.3 parts of a water scavenger. The plasticizer is diisononyl phthalate, the filler is heavy calcium carbonate, the carbon black is M570 carbon black, and the first catalyst is dibutyltin dilaurate. The water scavenger is p-toluenesulfonyl isocyanate. The preparation of the first polyurethane resin includes: placing 100 parts by mass of polyoxypropylene triol (number average molecular weight of 5000, moisture ≤300 ppm) in a reactor, heating to 65° C., adding 17.25 parts of MDI and 0.058 parts of dibutyltin dilaurate, and maintaining the temperature to react until the isocyanate content is detected to be 2.79%, thereby obtaining the first polyurethane resin; The second polyurethane resin is prepared by placing 100 parts by mass of polyoxypropylene glycol (number average molecular weight of 2000, moisture content ≤300 ppm) in a reactor, heating the reactor to 65° C., adding 50.78 parts of modified isocyanate and 0.075 parts of dibutyltin dilaurate, and maintaining the temperature to react until the isocyanate content is detected to be 1.67%, thereby obtaining the second polyurethane resin. The preparation of the modified isocyanate comprises: placing 504.6 parts by mass of HDI trimer and 634.74 parts of ethyl acetate in a reactor, heating the reactor to 65° C., then adding 130.14 parts of HEMA dropwise at a rate of 3 g / s, maintaining the temperature and reacting until the isocyanate content is 6.62% as determined by a test, and removing the ethyl acetate by vacuum distillation to obtain the modified isocyanate; The preparation of the modified adhesion promoter includes: placing 341.55 parts of bis(3-methoxysilylpropyl)amine, 142.15 parts of GMA, and 483.7 parts of ethyl acetate in a reactor, heating the temperature to 75°C, and maintaining the temperature for reaction until the infrared absorption peak of the epoxy group disappears to obtain a hydroxyl-containing GMA-modified silane; then, adding the hydroxyl-containing GMA-modified silane dropwise at a rate of 3 g / s to a reactor containing 504.6 parts of HDI trimer; maintaining the temperature for reaction at 65°C until the isocyanate content is detected to be 5.71%, and removing the ethyl acetate by reduced pressure distillation to obtain the modified adhesion promoter.

[0035] This embodiment also provides a method for preparing a high-strength polyurethane self-adhesive for vehicles, comprising the following steps: The first polyurethane resin, the second polyurethane resin, the plasticizer, the modified adhesion promoter, the filler, the carbon black, the first catalyst, and the water scavenger in the formulated amount are placed in a closed mixer and vacuumed to -0.098 MPa, and stirred for 60 minutes to obtain a uniform paste-like high-strength polyurethane self-adhesive for automobiles.

[0036] Example 5 This embodiment provides a high-strength polyurethane self-adhesive for automobiles. The raw materials for preparation include, by weight, 25 parts of a first polyurethane resin, 8 parts of a second polyurethane resin, 30 parts of a plasticizer, 5 parts of a modified adhesion promoter, 10 parts of a filler, 20.98 parts of carbon black, 0.02 parts of a first catalyst, and 1 part of a water scavenger. The plasticizer is diisononyl phthalate, the filler is calcined kaolin, the carbon black is M570 carbon black, and the first catalyst is dibutyltin dilaurate. The water scavenger is p-toluenesulfonyl isocyanate. The preparation of the first polyurethane resin includes: placing 100 parts by mass of polyoxypropylene triol (number average molecular weight of 5000, moisture ≤300 ppm) in a reactor, heating to 65° C., adding 17.25 parts of MDI and 0.058 parts of dibutyltin dilaurate, and maintaining the temperature to react until the isocyanate content is detected to be 2.79%, thereby obtaining the first polyurethane resin; The second polyurethane resin is prepared by placing 100 parts by mass of polyoxypropylene glycol (number average molecular weight of 2000, moisture content ≤300 ppm) in a reactor, heating the reactor to 65° C., adding 50.78 parts of modified isocyanate and 0.075 parts of dibutyltin dilaurate, and maintaining the temperature to react until the isocyanate content is detected to be 1.67%, thereby obtaining the second polyurethane resin. The preparation of the modified isocyanate comprises: placing 504.6 parts by mass of HDI trimer and 634.74 parts of ethyl acetate in a reactor, heating the reactor to 65° C., then adding 130.14 parts of HEMA dropwise at a rate of 3 g / s, maintaining the temperature and reacting until the isocyanate content is 6.62% as determined by a test, and removing the ethyl acetate by vacuum distillation to obtain the modified isocyanate; The preparation of the modified adhesion promoter includes: placing 341.55 parts of bis(3-methoxysilylpropyl)amine, 142.15 parts of GMA, and 483.7 parts of ethyl acetate in a reactor, heating the temperature to 75°C, and maintaining the temperature for reaction until the infrared absorption peak of the epoxy group disappears to obtain a hydroxyl-containing GMA-modified silane; then, adding the hydroxyl-containing GMA-modified silane dropwise at a rate of 3 g / s to a reactor containing 504.6 parts of HDI trimer; maintaining the temperature for reaction at 65°C until the isocyanate content is detected to be 5.71%, and removing the ethyl acetate by reduced pressure distillation to obtain the modified adhesion promoter.

[0037] This embodiment also provides a method for preparing a high-strength polyurethane self-adhesive for vehicles, comprising the following steps: The first polyurethane resin, the second polyurethane resin, the plasticizer, the modified adhesion promoter, the filler, the carbon black, the first catalyst, and the water scavenger in the formulated amount are placed in a closed mixer and vacuumed to -0.098 MPa, and stirred for 60 minutes to obtain a uniform paste-like high-strength polyurethane self-adhesive for automobiles.

[0038] Example 6 This embodiment provides a high-strength polyurethane self-adhesive for automobiles. The raw materials for preparation include, by weight, 25 parts of a first polyurethane resin, 8 parts of a second polyurethane resin, 22.65 parts of a plasticizer, 6 parts of a modified adhesion promoter, 20 parts of a filler, 18 parts of carbon black, 0.02 parts of a first catalyst, and 0.33 parts of a water scavenger. The plasticizer is diisononyl phthalate, the filler is heavy calcium carbonate, the carbon black is M570 carbon black, and the first catalyst is dibutyltin dilaurate. The water scavenger is p-toluenesulfonyl isocyanate. The preparation of the first polyurethane resin includes: placing 100 parts by mass of polyoxypropylene triol (number average molecular weight of 6000, moisture ≤300 ppm) in a reactor, heating to 65° C., adding 14.38 parts of MDI and 0.058 parts of dibutyltin dilaurate, and maintaining the temperature to react until the isocyanate content is detected to be 2.39%, thereby obtaining the first polyurethane resin; The second polyurethane resin is prepared by placing 100 parts by mass of polyoxypropylene glycol (number average molecular weight of 2000, moisture content ≤300 ppm) in a reactor, heating the reactor to 65° C., adding 50.78 parts of modified isocyanate and 0.075 parts of dibutyltin dilaurate, and maintaining the temperature to react until the isocyanate content is detected to be 1.67%, thereby obtaining the second polyurethane resin. The preparation of the modified isocyanate comprises: placing 504.6 parts by mass of HDI trimer and 634.74 parts of ethyl acetate in a reactor, heating the reactor to 65° C., then adding 130.14 parts of HEMA dropwise at a rate of 3 g / s, maintaining the temperature and reacting until the isocyanate content is 6.62% as determined by a test, and removing the ethyl acetate by vacuum distillation to obtain the modified isocyanate; The preparation of the modified adhesion promoter includes: placing 341.55 parts of bis(3-methoxysilylpropyl)amine, 142.15 parts of GMA, and 483.7 parts of ethyl acetate in a reactor, heating the temperature to 75°C, and maintaining the temperature for reaction until the infrared absorption peak of the epoxy group disappears to obtain a hydroxyl-containing GMA-modified silane; then, adding the hydroxyl-containing GMA-modified silane dropwise at a rate of 3 g / s to a reactor containing 504.6 parts of HDI trimer; maintaining the temperature for reaction at 65°C until the isocyanate content is detected to be 5.71%, and removing the ethyl acetate by reduced pressure distillation to obtain the modified adhesion promoter.

[0039] This embodiment also provides a method for preparing a high-strength polyurethane self-adhesive for vehicles, comprising the following steps: The first polyurethane resin, the second polyurethane resin, the plasticizer, the modified adhesion promoter, the filler, the carbon black, the first catalyst, and the water scavenger in the formulated amount are placed in a closed mixer and vacuumed to -0.098 MPa, and stirred for 60 minutes to obtain a uniform paste-like high-strength polyurethane self-adhesive for automobiles.

[0040] Example 7 This embodiment provides a high-strength polyurethane self-adhesive for automobiles. The raw materials for preparation include, by weight, 25 parts of a first polyurethane resin, 8 parts of a second polyurethane resin, 22.70 parts of a plasticizer, 6 parts of a modified adhesion promoter, 15 parts of a filler, 23 parts of carbon black, 0.1 parts of a first catalyst, and 0.2 parts of a water scavenger. The plasticizer is diisononyl phthalate, the filler is heavy calcium carbonate, the carbon black is M570 carbon black, and the first catalyst is dibutyltin dilaurate. The water scavenger is p-toluenesulfonyl isocyanate. The preparation of the first polyurethane resin includes: placing 100 parts by mass of polyoxypropylene triol (number average molecular weight of 5000, moisture ≤300 ppm) in a reactor, heating to 65° C., adding 17.25 parts of MDI and 0.058 parts of dibutyltin dilaurate, and maintaining the temperature to react until the isocyanate content is detected to be 2.79%, thereby obtaining the first polyurethane resin; The second polyurethane resin is prepared by placing 100 parts by mass of polyoxypropylene glycol (number average molecular weight of 4000, moisture content ≤300 ppm) in a reactor, heating the reactor to 65° C., adding 25.39 parts of modified isocyanate and 0.063 parts of dibutyltin dilaurate, and maintaining the temperature to react until the isocyanate content is 1% as detected, thereby obtaining the second polyurethane resin. The preparation of the modified isocyanate comprises: placing 504.6 parts by mass of HDI trimer and 634.74 parts of ethyl acetate in a reactor, heating the reactor to 65° C., then adding 130.14 parts of HEMA dropwise at a rate of 3 g / s, maintaining the temperature and reacting until the isocyanate content is 6.62% as determined by a test, and removing the ethyl acetate by vacuum distillation to obtain the modified isocyanate; The preparation of the modified adhesion promoter includes: placing 341.55 parts of bis(3-methoxysilylpropyl)amine, 142.15 parts of GMA, and 483.7 parts of ethyl acetate in a reactor, heating the temperature to 75°C, and maintaining the temperature for reaction until the infrared absorption peak of the epoxy group disappears to obtain a hydroxyl-containing GMA-modified silane; then, adding the hydroxyl-containing GMA-modified silane dropwise at a rate of 3 g / s to a reactor containing 504.6 parts of HDI trimer; maintaining the temperature for reaction at 65°C until the isocyanate content is detected to be 5.71%, and removing the ethyl acetate by reduced pressure distillation to obtain the modified adhesion promoter.

[0041] This embodiment also provides a method for preparing a high-strength polyurethane self-adhesive for vehicles, comprising the following steps: The first polyurethane resin, the second polyurethane resin, the plasticizer, the modified adhesion promoter, the filler, the carbon black, the first catalyst, and the water scavenger in the formulated amount are placed in a closed mixer and vacuumed to -0.098 MPa, and stirred for 60 minutes to obtain a uniform paste-like high-strength polyurethane self-adhesive for automobiles.

[0042] Example 8 This embodiment provides a high-strength polyurethane self-adhesive for automobiles. The raw materials for preparation include, by weight, 25 parts of a first polyurethane resin, 8 parts of a second polyurethane resin, 22.65 parts of a plasticizer, 6 parts of a modified adhesion promoter, 12 parts of a filler, 26 parts of carbon black, 0.05 parts of a first catalyst, and 0.3 parts of a water scavenger. The plasticizer is diisononyl phthalate, the filler is heavy calcium carbonate, the carbon black is M570 carbon black, and the first catalyst is dibutyltin dilaurate. The water scavenger is p-toluenesulfonyl isocyanate. The preparation of the first polyurethane resin includes: placing 100 parts by mass of polyoxypropylene triol (number average molecular weight of 5000, moisture ≤300 ppm) in a reactor, heating to 65° C., adding 17.25 parts of MDI and 0.058 parts of dibutyltin dilaurate, and maintaining the temperature to react until the isocyanate content is detected to be 2.79%, thereby obtaining the first polyurethane resin; The second polyurethane resin is prepared by placing 100 parts by mass of polyoxypropylene glycol (number average molecular weight of 2000, moisture content ≤300 ppm) in a reactor, heating the reactor to 65° C., adding 50.78 parts of modified isocyanate and 0.075 parts of dibutyltin dilaurate, and maintaining the temperature to react until the isocyanate content is detected to be 1.67%, thereby obtaining the second polyurethane resin. The preparation of the modified isocyanate comprises: placing 504.6 parts by mass of HDI trimer and 634.74 parts of ethyl acetate in a reactor, heating the reactor to 65° C., then adding 130.14 parts of HEMA dropwise at a rate of 3 g / s, maintaining the temperature and reacting until the isocyanate content is 6.62% as determined by a test, and removing the ethyl acetate by vacuum distillation to obtain the modified isocyanate; The preparation of the modified adhesion promoter includes: placing 341.55 parts of bis(3-methoxysilylpropyl)amine, 142.15 parts of GMA, and 483.7 parts of ethyl acetate in a reactor, heating the temperature to 75°C, and maintaining the temperature for reaction until the infrared absorption peak of the epoxy group disappears to obtain a hydroxyl-containing GMA-modified silane; then, adding the hydroxyl-containing GMA-modified silane dropwise at a rate of 3 g / s to a reactor containing 666.96 parts of IPDI trimer; maintaining the temperature for reaction at 65°C until the isocyanate content is detected to be 5.14%, and removing the ethyl acetate by reduced pressure distillation to obtain the modified adhesion promoter.

[0043] This embodiment also provides a method for preparing a high-strength polyurethane self-adhesive for vehicles, comprising the following steps: The first polyurethane resin, the second polyurethane resin, the plasticizer, the modified adhesion promoter, the filler, the carbon black, the first catalyst, and the water scavenger in the formulated amount are placed in a closed mixer and vacuumed to -0.098 MPa, and stirred for 60 minutes to obtain a uniform paste-like high-strength polyurethane self-adhesive for automobiles.

[0044] Comparative Example 1 This comparative example provides a high-strength polyurethane self-adhesive for automobiles. The raw materials for preparation include, by weight, 33 parts of a first polyurethane resin, 22.65 parts of a plasticizer, 6 parts of a modified adhesion promoter, 15 parts of a filler, 23 parts of carbon black, 0.05 parts of a first catalyst, and 0.3 parts of a water scavenger; the plasticizer is diisononyl phthalate, the filler is heavy calcium carbonate, the carbon black is M570 carbon black, and the first catalyst is dibutyltin dilaurate; the water scavenger is p-toluenesulfonyl isocyanate; The preparation of the first polyurethane resin includes: placing 100 parts by mass of polyoxypropylene triol (number average molecular weight of 5000, moisture ≤300 ppm) in a reactor, heating to 65° C., adding 17.25 parts of MDI and 0.058 parts of dibutyltin dilaurate, and maintaining the temperature to react until the isocyanate content is detected to be 2.79%, thereby obtaining the first polyurethane resin; The preparation of the modified adhesion promoter includes: placing 341.55 parts of bis(3-methoxysilylpropyl)amine, 142.15 parts of GMA, and 483.7 parts of ethyl acetate in a reactor, heating the temperature to 75°C, and maintaining the temperature for reaction until the infrared absorption peak of the epoxy group disappears to obtain a hydroxyl-containing GMA-modified silane; then, adding the hydroxyl-containing GMA-modified silane dropwise at a rate of 3 g / s to a reactor containing 504.6 parts of HDI trimer; maintaining the temperature for reaction at 65°C until the isocyanate content is detected to be 5.71%, and removing the ethyl acetate by reduced pressure distillation to obtain the modified adhesion promoter.

[0045] This comparative example also provides a method for preparing a high-strength polyurethane self-adhesive for vehicles, comprising the following steps: The first polyurethane resin, plasticizer, modified adhesion promoter, filler, carbon black, first catalyst and dehydrating agent in the formulated amount are placed in a closed mixer and vacuumed to -0.098 MPa, and stirred for 60 minutes to obtain a uniform paste-like high-strength polyurethane self-adhesive for automobiles.

[0046] Comparative Example 2 The comparative example provides a high-strength polyurethane self-adhesive for vehicles, and the preparation raw materials include, in mass parts, 25 parts of a first polyurethane resin, 8 parts of a second polyurethane resin, 26.65 parts of a plasticizer, 2 parts of γ-glycidoxypropyltrimethoxysilane, 15 parts of a filler, 23 parts of carbon black, 0.05 parts of a first catalyst, and 0.3 parts of a water-removing agent; the plasticizer is diisononyl phthalate, the filler is heavy calcium carbonate, the carbon black is M570 carbon black, the first catalyst is dibutyltin dilaurate, and the water-removing agent is p-toluenesulfonylisocyanate. The preparation of the first polyurethane resin includes: placing 100 parts of polyoxypropylene triol (with a number average molecular weight of 5000 and a water content of ≤300 ppm) in a reactor, heating to 65°C, adding 17.25 parts of MDI and 0.058 parts of dibutyltin dilaurate, and reacting under heat until the isocyanate content is detected to be 2.79%, to obtain the first polyurethane resin. The preparation of the second polyurethane resin includes: placing 100 parts of polyoxypropylene diol (with a number average molecular weight of 2000 and a water content of ≤300 ppm) in a reactor, heating to 65°C, adding 50.78 parts of modified isocyanate and 0.075 parts of dibutyltin dilaurate, and reacting under heat until the isocyanate content is detected to be 1.67%, to obtain the second polyurethane resin. The preparation of the modified isocyanate includes: placing 504.6 parts of HDI trimer and 634.74 parts of ethyl acetate in a reactor, heating to 65°C, then adding 130.14 parts of HEMA drop by drop at a speed of 3 g / s, reacting under heat until the isocyanate content is detected to be 6.62%, and removing the ethyl acetate by vacuum distillation, to obtain the modified isocyanate. The comparative example also provides a preparation method of a high-strength polyurethane self-adhesive for vehicles, and the steps include: The formula amount of the first polyurethane resin, the second polyurethane resin, the plasticizer, the γ-glycidoxypropyltrimethoxysilane, the filler, the carbon black, the first catalyst, and the water-removing agent are placed in a sealed stirrer, vacuumized to -0.098 MPa, and stirred for 60 min to obtain a uniform paste-shaped high-strength polyurethane self-adhesive for vehicles.

[0047] The high-strength polyurethane self-adhesives for vehicles prepared in Examples 1-8 and Comparative Examples 1-2 are tested for surface dry time, tensile property, Shore hardness, shear property, tear strength, peeling adhesion, water resistance, heat resistance, damp heat resistance, climate alternating resistance, and artificial climate accelerated aging resistance (xenon arc lamp), and the test conditions are as follows, and the test results are shown in Tables 2-3.

[0048] (1) Surface dry time: tested according to the standard of GB / T 13477.5-2002 Building Sealing Materials Test Methods Part 5: Determination of Surface Dry Time.

[0049] (2) Tensile properties: Tested in accordance with GB / T 528-2009 Vulcanized rubber or thermoplastic rubber - Determination of tensile stress-strain properties.

[0050] (3) Shore hardness: Tested in accordance with GB / T 531.1-2008 Rubber, vulcanized or thermoplastic, indentation hardness test method Part 1: Shore hardness tester method.

[0051] (4) Shear performance: Tested in accordance with the standard "GB / T 7124-2008 Determination of tensile shear strength of adhesives (rigid material to rigid material)".

[0052] (5) Tear strength: Tested in accordance with GB / T 529-2008 Vulcanized rubber or thermoplastic rubber - Determination of tear strength (trouser-shaped, right-angled and crescent-shaped specimens).

[0053] (6) Peel adhesion: Tested in accordance with the standard DVS1618 2002 Elastic thick film bonding in railway vehicles.

[0054] The specific implementation steps are as follows: first clean the surface of the substrate with a detergent, and after drying, use a glue gun to apply 5 strips of polyurethane composition with a width of about 10mm and a length of at least 50mm to the surface of the substrate coated with the primer. Place the substrate with the glue strips in a standard state (23℃ / 50%RH) for 7 days, then use a knife to cut the glue strip to the attachment surface, and use needle-nose pliers to peel the glue (peeling angle 130~160°). During the peeling process, cut the glue strip horizontally to the attachment surface every 5~10mm, and the interval time between cutting sections is about 3s. Continue to apply load to the material, and the test length must be at least 50mm. (7) Water resistance, heat resistance, moisture and heat resistance, resistance to climate changes, and accelerated aging by artificial climate shall be tested in accordance with the standard “QC / T1024-2015 One-component polyurethane sealant for automobiles”.

[0055] Table 2 Performance test results of automotive high-strength polyurethane self-adhesives of Examples 1 to 5

[0056] Note: CF-cohesive failure, AF-interfacial failure.

[0057] Table 3 Performance test results of automotive high-strength polyurethane self-adhesives of Examples 6-8 and Comparative Examples 1-2

[0058] Note: CF-cohesive failure, AF-interfacial failure.

[0059] As can be seen from the results in Tables 2 and 3, the automotive high-strength polyurethane self-adhesives of Examples 1 to 8 have the characteristics of high bonding strength, excellent mechanical properties, durability, and weather resistance. This shows that the present invention uses triisocyanate to introduce HEMA into the second polyurethane resin and introduces GMA into the modified adhesion promoter, which not only increases the crosslinking density of the polyurethane resin system, thereby improving its strength, but also promotes the durability and weather resistance of the adhesive. In addition, the introduced acrylic ester compound has good migration ability and excellent adhesion to various substrates. The modified silane can achieve a self-adhesive effect without a primer and activator, which can significantly improve the work efficiency of the main engine factory and better meet the environmental protection requirements of modern industry.

[0060] Comparing Example 4 with Comparative Examples 1 and 2 shows that removing the second polyurethane resin or the modified adhesion promoter affects the bond strength of the polyurethane self-adhesive. This indicates that the introduction of the acrylate compound HEMA in the second polyurethane resin and the acrylate compound GMA in the modified adhesion promoter significantly enhances the interfacial contact between the adhesive and substrates such as glass and sheet metal by leveraging the excellent mobility and wettability of the acrylate compounds. Furthermore, the ester groups (-COO) of the acrylates can form numerous hydrogen bonds with the substrate surface, resulting in strong adsorption. Furthermore, the siloxane groups (-Si-OR) in the modified adhesion promoter form chemical bonds (Si-O-Si) with the hydroxyl groups on the substrate surface. The acrylate double bonds in the second polyurethane resin physically anchor the adhesive to the substrate surface during curing, further enhancing interfacial bonding. This dual mechanism of chemical bonding and physical adsorption fundamentally ensures the high bond strength of the polyurethane self-adhesive.

[0061] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit the scope of protection of the present invention. Although the present invention is described in detail with reference to the preferred embodiments, it is not limited to those listed in the embodiments. Those skilled in the art should understand that the technical solutions of the present invention can be modified or replaced by equivalents without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A high-strength polyurethane self-adhesive for automobiles, characterized in that: The raw materials for preparation include, by mass, 20-30 parts of a first polyurethane resin, 5-10 parts of a second polyurethane resin, 20-30 parts of a plasticizer, 5-10 parts of a modified adhesion promoter, 10-20 parts of a filler, 18-26 parts of carbon black, 0.02-0.10 parts of a first catalyst, and 0.2-1.0 parts of a dehydrating agent; wherein, The first polyurethane resin is prepared by reacting polyoxypropylene triol and a first cyanate ester; The second polyurethane resin is prepared by reacting a polyether diol and a modified isocyanate, and the modified isocyanate is prepared by dropwise reacting hydroxyethyl methacrylate and a second cyanate; The modified adhesion promoter is prepared by dropwise reaction of hydroxyl-containing GMA-modified silane and a third cyanate ester, wherein the hydroxyl-containing GMA-modified silane is prepared by ring-opening reaction of glycidyl methacrylate and secondary aminosilane; The first cyanate is diisocyanate, and the second cyanate and the third cyanate are both triisocyanate.

2. The high-strength polyurethane self-adhesive adhesive for vehicles according to claim 1, characterized in that: The number average molecular weight of the polyoxypropylene triol is 5000-8000, and the number average molecular weight of the polyether diol is 2000-4000.

3. The high-strength polyurethane self-adhesive adhesive for vehicles according to claim 1, characterized in that: The first cyanate is selected from at least one of TDI, MDI, HDI, IPDI, NDI, and XDI; the second cyanate and the third cyanate are each independently selected from at least one of HDI trimer, IPDI trimer, TDI trimer, triphenylthiophosphate triisocyanate, and triphenylmethane triisocyanate.

4. The high-strength polyurethane self-adhesive adhesive for vehicles according to claim 1, characterized in that: The plasticizer is selected from at least one of phthalates, alkyl phenyl sulfonates, adipates, epoxy esters, and phosphates.

5. The high-strength polyurethane self-adhesive adhesive for vehicles according to claim 1, characterized in that: The filler is selected from at least one of heavy calcium carbonate, modified calcium carbonate, calcined kaolin, talc powder and dolomite powder; the first catalyst is selected from at least one of organic tin, organic bismuth, organic zinc and organic amine.

6. The high-strength polyurethane self-adhesive adhesive for vehicles according to claim 1, characterized in that: The secondary aminosilane is selected from at least one of N-phenyl-3-aminopropyltrimethoxysilane, N-n-butyl-3-aminopropyltrimethoxysilane, N-n-butyl-3-aminopropyltriethoxysilane, bis(3-methoxysilylpropyl)amine, and bis(3-ethoxysilylpropyl)amine.

7. The high-strength polyurethane self-adhesive adhesive for vehicles according to claim 1, characterized in that: The preparation of the first polyurethane resin includes: placing polyoxypropylene triol, a first cyanate ester, and a second catalyst in a reactor, and reacting at a heat-insulating temperature until NCO reaches a theoretical value to obtain the first polyurethane resin.

8. The high-strength polyurethane self-adhesive adhesive for vehicles according to claim 1, characterized in that: The preparation of the second polyurethane resin comprises: placing polyether diol, modified isocyanate, and a third catalyst in a reactor, and reacting at a temperature of 100°C until NCO reaches a theoretical value, thereby obtaining the second polyurethane resin; The preparation of the modified isocyanate includes: placing the second cyanate and the first solvent in a reactor, adding hydroxyethyl methacrylate dropwise, keeping the temperature to react until the NCO theoretical value is reached, and performing a first post-treatment to obtain the modified isocyanate.

9. The high-strength polyurethane self-adhesive adhesive for vehicles according to claim 1, characterized in that: The preparation of the modified adhesion promoter includes: placing secondary amino silane, glycidyl methacrylate, and a second solvent in a reactor, carrying out a heat-insulating reaction until the infrared absorption peak of the epoxy group disappears to obtain a hydroxyl-containing GMA-modified silane, then dropwise adding the hydroxyl-containing GMA-modified silane to a third cyanate ester, carrying out a heat-insulating reaction until the NCO reaches a theoretical value, and performing a second post-treatment to obtain the modified adhesion promoter.

10. A method for preparing the high-strength polyurethane self-adhesive for vehicles according to any one of claims 1 to 9, characterized in that the steps include: The first polyurethane resin, the second polyurethane resin, the plasticizer, the modified adhesion promoter, the filler, the carbon black, the first catalyst and the water scavenger in the formulated amount are placed in a closed mixer and vacuum-stirred until a uniform paste is formed to obtain a high-strength polyurethane self-adhesive adhesive for automobiles.

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