Bi-component polyurethane adhesive as well as preparation method and application thereof

Abstract

The invention provides a bi-component polyurethane adhesive as well as a preparation method and application thereof, and the bi-component polyurethane adhesive comprises a component A and a component B, the component A is prepared from the following raw materials: hydroxyl-terminated polybutadiene, a chain extender, a tackifier, an antioxidant, a first inorganic filler, a catalyst and a first thixotropic agent; the component B is prepared from the following raw materials: an isocyanate-terminated prepolymer, first polyisocyanate, a first plasticizer, a second inorganic filler, a second thixotropic agent, a water absorbent and a silane coupling agent; the isocyanate-terminated prepolymer is prepared from the following raw materials: hydroxyl-terminated polybutadiene, second polyisocyanate and a plasticizer; the volume ratio of the component A to the component B is 1: 1. The prepared double-component polyurethane adhesive is high in strength, high in elongation, high in short-term strength and resistant to high and low temperature, damp and heat and hot water aging for a long time.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of adhesives, and particularly relates to a two-component polyurethane adhesive as well as a preparation method and application thereof. BACKGROUND

[0002] In order to achieve the requirement of light weight of automobiles, glass fiber reinforced plastic (FRP), carbon fiber composite material (CFRP), ABS, PP, PC, ASA and the like are widely used in automobile exterior parts. However, these materials have poor resistance to wet heat, the acrylate adhesive has a large odor, and the toughness is insufficient, which cannot meet the requirements of reliable bonding. Relatively speaking, the polyurethane adhesive can balance the strength and toughness, has good resistance to wet heat, and is more and more widely used in the bonding of composite materials.

[0003] With the development of new material technology, the automobile exterior materials are diversified, and the adhesive needs to have good adhesion to various substrates. Moreover, with the development of automation, the production rhythm is accelerated, and the adhesive needs to have a faster curing speed under the premise of maintaining a long surface drying time. In order to adapt to the complex driving environment of automobiles, resist the influence of material load, high and low temperature and humid environment, the adhesive needs to have high strength, high elongation and aging resistance.

[0004] Therefore, it is necessary to develop a two-component polyurethane adhesive with high strength, high elongation, high short-term strength, long-term resistance to high and low temperature, resistance to wet heat and hot water aging, which is used for bonding of automobile exterior composite materials. SUMMARY

[0005] In view of the deficiencies in the prior art, the application provides a two-component polyurethane adhesive as well as a preparation method and application thereof. The two-component polyurethane adhesive prepared has high strength, high elongation, high short-term strength, long-term resistance to high and low temperature, resistance to wet heat and hot water aging.

[0006] To achieve the above-mentioned purpose, the application adopts the following technical solutions: In a first aspect, the application provides a two-component polyurethane adhesive, which comprises A component and B component. The A component is prepared from the following raw materials in parts by weight: 40-45 parts of hydroxyl-terminated polybutadiene, 3-7 parts of chain extender, 7-10 parts of tackifier, 0.5-0.8 parts of antioxidant, 35-45 parts of first inorganic filler, 0.1-0.6 parts of catalyst, and 0.5-2 parts of first thixotropic agent. The B component is prepared from the following raw materials in parts by weight: 23-25 parts of isocyanate-terminated prepolymer, 10-15 parts of first polyisocyanate, 7-15 parts of first plasticizer, 45-47 parts of second inorganic filler, 1-2 parts of second thixotropic agent, 0.3-0.5 parts of water absorbent, and 0.3-0.5 parts of silane coupling agent. The mass ratio of the A component and the B component is 1:1.

[0007] Preferably, the end isocyanate group prepolymer is prepared from the following raw materials by weight: 40-50 parts of end hydroxyl polybutadiene, 32-40 parts of second polyisocyanate, 24-26 parts of second plasticizer.

[0008] Preferably, the end hydroxyl polybutadiene has a relative molecular weight of 2000-3000 and a hydroxyl value of 45-56 mg KOH / g, and in some embodiments, one of Cray Valley's R45V, Wanhua Chemical's POLYVEST HT is used; and / or, The relative molecular weight of the chain extender is 80-200, and the dihydric alcohol in the molecular structure does not contain an ether bond, and in some embodiments, one of 1,4-butanediol, 2-ethyl-1,3-hexanediol, 2,2,4-trimethyl-1,3-pentanediol, 2-butyl-2-ethyl-1,3-propanediol is used; and / or, The structure of the tackifier is as follows: Wherein, n=2 or 3, R is H or C m H 2m-1 m is an integer from 1 to 12, and in some embodiments, one of propylene glycol p-toluenesulfide, dodecyl phenoxy propanol, propylene glycol butyl phenyl ether is preferred; and / or, The antioxidant is a liquid hindered phenolic antioxidant, and in some embodiments, the antioxidant is selected from BASF Irganox®1135; and / or, The first inorganic filler is nano calcium carbonate, and in some embodiments, the first inorganic filler is selected from CCS25 of Guangxi Huana New Material; and / or, The catalyst is at least one of 1,3-dimethylimidazole, Wanhua KOSMOS 16, T131; and / or, The first thixotropic agent or the second thixotropic agent is fumed silica. In some embodiments, Wanhua Chemical's R972 is used.

[0009] Preferably, the first polyisocyanate is one of polymeric MDI, carbodiimide modified MDI, and liquefied MDI, and the first polyisocyanate is selected from one of Wanhua Chemical's PM200, CDMDI-100L, and MDI-50; and / or, The first plasticizer is DIDP, DINP, or IPPP, and the first plasticizer is one of DIDP, DINP, and IPPP; and / or, The second inorganic filler is ultra-fine calcium carbonate, aluminum hydroxide, silicon powder or talc powder, the particle size of the second inorganic filler is 10-20 μm, the water content is ≤500 ppm, and in some embodiments, Omyacarb 2T of Omya is selected; and / or, The water absorption agent is p-toluenesulfonyl isocyanate; and / or, The silane coupling agent is one of γ-glycidoxypropyltrimethoxysilane, 3-(2,3-epoxypropoxy)propylmethyldimethoxysilane, γ-glycidoxypropyltriethoxysilane, β-(3,4-epoxycyclohexyl)-ethyltriethoxysilane, β-(3,4-epoxycyclohexyl)-ethyltrimethoxysilane, and 3-(2,3-epoxypropoxy)propylmethyldiethoxysilane.

[0010] Preferably, the second polyisocyanate is one of polymeric MDI, carbodiimide-modified MDI, HDI trimer. In some embodiments, the second polyisocyanate is selected from one of Wanhua PM200, CDMDI-100L, Covestro Desmodur N3300.

[0011] In a second aspect, the present application provides a preparation method of the two-component polyurethane adhesive, which comprises the following steps: S1, mixing hydroxyl-terminated polybutadiene, antioxidant, first inorganic filler, catalyst, and first thixotropic agent to obtain a premix; S2, mixing the premix, chain extender, and tackifier to obtain component A; S3, mixing isocyanate-terminated prepolymer, first polyisocyanate, first plasticizer, second inorganic filler, second thixotropic agent, water absorption agent, and silane coupling agent to obtain component B, wherein the volume ratio of component A to component B is 1:1.

[0012] Preferably, the isocyanate-terminated prepolymer is prepared from the following raw materials by weight: 40-50 parts of hydroxyl-terminated polybutadiene, 32-40 parts of second polyisocyanate, and 24-26 parts of second plasticizer. In step S3, the preparation method of the isocyanate-terminated prepolymer is as follows: after hydroxyl-terminated polybutadiene and second plasticizer are dehydrated, the hydroxyl-terminated polybutadiene, second plasticizer, and second polyisocyanate are mixed to obtain the isocyanate-terminated prepolymer.

[0013] Preferably, after the hydroxyl-terminated polybutadiene and second plasticizer are dehydrated, the water content is less than 500 ppm.

[0014] Preferably, the hydroxyl-terminated polybutadiene, the second plasticizer and the second polyisocyanate are mixed and reacted at a temperature of 70-80℃ for 2h to obtain an isocyanate-terminated prepolymer.

[0015] In a third aspect, the application provides the use of the two-component polyurethane adhesive or the two-component polyurethane adhesive prepared by the preparation method in bonding automobile exterior composite materials.

[0016] Compared with the prior art, the application has the following beneficial effects: (1) The application is made of a specific chain extender, a specific structure tackifier, a hydroxyl-terminated polybutadiene, a first inorganic filler, an antioxidant, a first thixotropic agent and a catalyst to form the A component, and an isocyanate-terminated prepolymer, a first polyisocyanate, a water absorbent, a silane coupling agent, a second inorganic filler and a second thixotropic agent to form the B component, wherein the isocyanate-terminated prepolymer comprises the hydroxyl-terminated polybutadiene, a second polyisocyanate and a second plasticizer in a specific ratio. The hydroxyl-terminated polybutadiene with a multi-hydroxyl structure, the chain extender and the isocyanate-terminated prepolymer and the polyisocyanate are reacted to form a mutual transmission network structure. The selected tackifier has a single-hydroxyl structure and can be end-capped with part of the isocyanate, so as to effectively control the cross-linking degree of the adhesive molecules, balance the strength and elongation. In addition, the special benzene ring structure of the tackifier has a conjugated electron effect, a low molecular surface tension and a strong hydrophobicity, which is beneficial to improving the adhesion of the adhesive to low-polarity materials and the water aging resistance of the adhesive, and the benzene ring structure has rigidity, which can assist in improving the heat resistance of the adhesive. The selected chain extender does not contain an ether bond, and the molecular chain is a fatty chain after participating in the cross-linking reaction, which can further improve the hydrophobicity of the adhesive. It is worth emphasizing that the above synergistic effects can achieve good long-term heat resistance and water aging resistance.

[0017] (2) The two-component polyurethane adhesive of the application is mixed and used according to a certain volume ratio of 1:1, the surface drying time is ≥300s, the adhesive after curing achieves 100% cohesive failure to PP, PC, ABS, SMC, PET and other composite materials, the shear strength at room temperature after curing for 30min is ≥0.6MPa, the complete curing adhesive strength is ≥3.0MPa, the bulk strength is ≥3.0MPa, the elongation at break is ≥300%, the shear strength after aging at 70℃*95%RH for 1344h, aging at 90℃ for 1344h, aging at 120℃ for 72h and hot water immersion at 40℃ for 1344h is ≥2.5MPa, and the adhesion still maintains 100% cohesive failure. DETAILED DESCRIPTION

[0018] The application will be further described in connection with the following specific examples so that those skilled in the art will more clearly understand the application.

[0019] Example 1 A two-component polyurethane adhesive is provided, the composition of which is shown in Table 1: Table 1

[0020] The preparation method of the two-component polyurethane adhesive of the present example comprises the following steps: Preparation of A component: R45V, CCS25, KOSMOS 16, R972 are weighed according to the composition in Table 1, vacuumized, stirred and dispersed uniformly, and then the vacuum is released with dry nitrogen. 1,4-Butanediol, propylene glycol p-toluenesulfone ether, and Irganox®1135 are added according to the measurement, vacuumized, stirred and dispersed uniformly to obtain A1 component.

[0021] Preparation of prepolymer 1: R45V and DIDP are weighed according to the composition in Table 1, dehydrated to a water content of less than 500 ppm, and then PM200 is added at a temperature below 50°C, mixed uniformly, and reacted at a temperature of 70°C for 2h to obtain prepolymer 1.

[0022] Preparation of B component: weighed according to the composition in Table 1, vacuumized, stirred and dispersed uniformly to obtain B1 component The A1 component and the B1 component are sealed and stored, and mixed according to a volume ratio of 1:1 before use.

[0023] Example 2 A two-component polyurethane adhesive is provided, the composition of which is shown in Table 2: Table 2

[0024] The preparation method of the two-component polyurethane adhesive of the present example comprises the following steps: Preparation of A component: HT, CCS25, 1,3-dimethylimidazole, R972 are weighed according to the composition in Table 2, vacuumized, stirred and dispersed uniformly, and then the vacuum is released with dry nitrogen. 2-Ethyl-1,3-hexanediol, propylene glycol butyl phenyl ether, and Irganox®1135 are added according to the measurement, vacuumized, stirred and dispersed uniformly to obtain A1 component.

[0025] Preparation of prepolymer 2: R45V and DINP are weighed according to the composition in Table 2, dehydrated to a water content of less than 500 ppm, and then CDMDI-100L is added at a temperature below 50°C, mixed uniformly, and reacted at a temperature of 80°C for 2h to obtain prepolymer 2.

[0026] Preparation of B component: weigh according to the composition in Table 2, vacuumize, stir and disperse uniformly to obtain B2 component; Seal and store A2 component and B2 component, and mix according to the volume ratio of 1:1 when used.

[0027] Example 3 A two-component polyurethane adhesive is provided, and the composition is shown in Table 3: Table 3

[0028] The preparation method of the two-component polyurethane adhesive of the present example comprises the following steps: Preparation of A component: weigh R45V, CCS25, T131 and R972 according to the composition in Table 3, vacuumize, stir and disperse uniformly, and remove the vacuum with dry nitrogen. Add 2,2,4-trimethyl-1,3-pentanediol, dodecylphenoxypropanol and Irganox®1135 according to the measurement, vacuumize, stir and disperse uniformly to obtain A3 component.

[0029] Preparation of prepolymer 3: weigh R45V and IPPP according to the composition in Table 3, dehydrate to less than 500 ppm of water, add MDI-50 at a temperature lower than 50°C, mix uniformly, and react for 2h at a temperature of 70-80°C to obtain prepolymer 3.

[0030] Preparation of B component: weigh according to the composition in Table 3, vacuumize, stir and disperse uniformly to obtain B3 component.

[0031] Seal and store A3 component and B3 component, and mix according to the volume ratio of 1:1 when used.

[0032] Example 4 A two-component polyurethane adhesive is provided, and the composition is shown in Table 4: Table 4

[0033] The preparation method of the two-component polyurethane adhesive of the present example comprises the following steps: Preparation of A component: weigh HT, CCS25, T131 and R972 according to the composition in Table 4, vacuumize, stir and disperse uniformly, and remove the vacuum with dry nitrogen. Add 2-butyl-2-ethyl-1,3-propanediol, propylene glycol butyl phenyl ether and Irganox®1135 according to the measurement, vacuumize, stir and disperse uniformly to obtain A4 component.

[0034] Preparation of prepolymer 4: HT and IPPP were weighed according to the composition in Table 4, dehydrated to moisture less than 500 ppm, PM200 was added under the condition of temperature less than 50℃, mixed uniformly, and reacted at a temperature of 75℃ for 2h to obtain the prepolymer 4.

[0035] Preparation of B component: weigh according to the composition in Table 4, vacuumize, and stir to disperse uniformly to obtain B4 component.

[0036] The A4 component and the B4 component were sealed and stored, and were mixed according to a volume ratio of 1:1 when used.

[0037] Comparative Example 1 A preparation method of a two-component polyurethane adhesive was provided, the components and the preparation method were the same as those in Example 2, except that the propylene glycol butyl phenyl ether in the A component was replaced by 2-ethyl-1,3-hexanediol.

[0038] Comparative Example 2 A preparation method of a two-component polyurethane adhesive was provided, the components and the preparation method were the same as those in Example 2, except that the 1,3-dimethylimidazole in the A component was replaced by dibutyltin dilaurate.

[0039] Comparative Example 3 A preparation method of a two-component polyurethane adhesive was provided, the components and the preparation method were the same as those in Example 2, except that the 2-ethyl-1,3-hexanediol in the A component was replaced by dipropylene glycol.

[0040] Performance test The two-component polyurethane adhesives of Examples 1 to 4 and Comparative Examples 1 to 3 were respectively tested according to the following method.

[0041] (1) Test of surface dry time: test according to B method in GB / T 13477.5 at 23±2℃ and humidity of (50%±2%) RH.

[0042] (2) Test of shear strength after curing at room temperature for 30min: wipe the surface to be adhered with anhydrous ethanol, and then ionize the surface to be adhered after the anhydrous ethanol evaporates, with a dyn value of ≥48. Mix the A and B components uniformly according to the proportion, adhere the PP test piece, prepare a shear test piece, and test the shear strength after curing the shear test piece at a temperature of (23±2)℃ and a relative humidity of (50±2)% RH for 30min, with a tensile speed of 50mm / min, and record the shear strength value and the failure mode.

[0043] (3) Shear strength test after 7 days of room temperature curing: wipe the surface to be bonded of the PP with anhydrous ethanol, and after the anhydrous ethanol evaporates, ionize the surface to be bonded, with a dyne value of 48 or more. According to the GB / T 7124-2008 standard, mix the A and B components uniformly in proportion, bond the PP test piece, prepare a shear test piece, and cure the shear test piece in an environment with a temperature of (23 ± 2) °C and a relative humidity of (50 ± 2) %RH for 7 days. Test the shear strength with a tensile speed of 50 mm / min, and record the shear strength value.

[0044] (4) Tensile strength and elongation at break test: After mixing the A and B components uniformly in proportion, press them into a sheet with a thickness of about 2 mm, and cure them in an environment with a temperature of (23 ± 2) °C and a relative humidity of (50 ± 2) %RH for 7 days. Test according to the GB / T 1040.1-2018 standard, using a type I knife, and a tensile speed of 50 mm / min.

[0045] (5) Adhesion test: clean the surface of the substrate with anhydrous ethanol, and after the anhydrous ethanol evaporates, treat the surface of the substrate with plasma or flame, with a dyne value of 48 or more. The PC and ABS can not be treated with plasma or flame. Mix the A and B components uniformly in proportion, and coat a glue strip with dimensions of about 100 mm x 20 mm x 2 mm on the substrate. If necessary, flatten the surface of the glue strip to ensure that it fully contacts the substrate. Place the glue strip in an environment with a temperature of (23 ± 2) °C and a relative humidity of (50 ± 5) %RH for 7 days of curing. Hold one end of the cured glue strip with a pair of pliers, pull the glue strip at an angle of 180°, and cut the glue strip at an angle of 60° to the test piece along the horizontal direction of the glue strip axis. Determine the failure mode according to Table 5.

[0046] Table 5: Corresponding table for indicating the failure mode of two-component polyurethane adhesive bonding

[0047] (6) Shear strength and adhesion test after 120°C aging: The test piece preparation method is the same as method (3) and (5). After curing the test piece in an environment with a temperature of (23 ± 2) °C and a relative humidity of (50 ± 5) %RH for 7 days, place it in a 120°C test chamber for 72 hours of aging, take it out and place it at room temperature for 24 hours, and test the shear strength and adhesion according to methods (3) and (5).

[0048] (7) Shear strength and adhesion test after 90°C aging: The test piece preparation method is the same as method (3) and (5). After curing the test piece in an environment with a temperature of (23 ± 2) °C and a relative humidity of (50 ± 5) %RH for 7 days, place it in a 90°C test chamber for 1344 hours of aging, take it out and place it at room temperature for 24 hours, and test the shear strength and adhesion according to methods (3) and (5).

[0049] (8) Shear strength and adhesion test after aging at 70℃*95% RH: The test pieces were prepared according to the method (3) and (5), and then cured at a temperature of (23±2)℃ and a relative humidity of (50±5)% RH for 7 days. Then the test pieces were put into a 70℃*95% RH test chamber for aging for 1344h, and then taken out and placed at room temperature for 24h. The shear strength and adhesion were tested according to the method (3) and (5).

[0050] (9) Shear strength and adhesion test after aging in 40℃ water: The test pieces were prepared according to the method (3) and (5), and then cured at a temperature of (23±2)℃ and a relative humidity of (50±5)% RH for 7 days. Then the test pieces were put into a 40℃ water tank for aging for 1344h, and then taken out and placed at room temperature for 24h. The shear strength and adhesion were tested according to the method (3) and (5).

[0051] The corresponding test results are shown in Table 6 below: Table 6 Performance test result statistics table

[0052] As can be seen from Table 6, in the comparative example 1, the blocking and hydrophobicity of the tackifier are lost, the crosslinking degree of the adhesive is relatively high, the bulk strength is relatively high, and the elongation is relatively low. The adhesion is good before aging, and the shear strength is relatively high. However, after aging, the bulk strength exceeds the adhesion between the adhesive and the surface of the substrate, and even in the presence of the silane coupling agent, partial debonding occurs. In particular, after high-temperature and high-humidity aging and hot water aging, the debonding ratio is higher, the shear strength after aging under various conditions is greatly attenuated, and is not more than 2.5MPa. Therefore, the tackifier used in the present application has the effect of enhancing the adhesion after aging. The catalyst in the comparative example 2 does not have a delay effect. Compared with the example 2, even if the skin drying time is greatly shortened, the shear strength after room temperature curing for 30min is only 0.12MPa, which is far lower than the short-term strength value of the example. The chain extender with ether bond structure is used in the comparative example 3, and there is no difference in conventional performance. However, after wet heat and hot water aging, debonding occurs to different degrees, the shear strength is greatly attenuated, and is lower than 2.5MPa. It is shown that the ether bond structure has a hygroscopic effect in the aging process, which weakens the adhesive interface and is not conducive to achieving reliable adhesion. The adhesive in the examples 1 to 4 has high strength and elongation, high short-term curing strength, and adhesion after aging that remains within 100% cohesive failure. The comprehensive performance is good, and can meet the performance requirements of long-term reliable adhesion of automobile exterior composite materials.

[0053] In the present application, other raw materials or structures not specifically described are already present in the prior art, and can be directly purchased from the market.

[0054] The above merely preferred embodiments of the present application and are not intended to limit the protection scope of the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A two-component polyurethane adhesive, characterized in that, Includes component A and component B; Component A is prepared from the following raw materials in parts by weight: 40-45 parts hydroxyl-terminated polybutadiene, 3-7 parts chain extender, 7-10 parts tackifier, 0.5-0.8 parts antioxidant, 35-45 parts first inorganic filler, 0.1-0.6 parts catalyst, and 0.5-2 parts first thixotropic agent; Component B is prepared from the following raw materials in parts by weight: 23-25 ​​parts of terminal isocyanate prepolymer, 10-15 parts of first polyisocyanate, 7-15 parts of first plasticizer, 45-47 parts of second inorganic filler, 1-2 parts of second thixotropic agent, 0.3-0.5 parts of water absorbent, and 0.3-0.5 parts of silane coupling agent; The volume ratio of component A to component B is 1:

1.

2. The two-component polyurethane adhesive according to claim 1, characterized in that, The isocyanate-terminated prepolymer is prepared from the following parts by weight of raw materials: 40-50 parts of hydroxyl-terminated polybutadiene, 32-40 parts of a second polyisocyanate, and 24-26 parts of a second plasticizer.

3. The two-component polyurethane adhesive according to claim 1, characterized in that, The hydroxyl-terminated polybutadiene has a relative molecular weight of 2000-3000 and a hydroxyl value of 45-56 mg KOH / g; and / or, The chain extender has a relative molecular weight of 80-200 and is a diol whose molecular structure does not contain ether bonds; and / or, The structure of the thickener is as follows: Where n = 2 or 3, and R is H or C. m H 2m-1 m is an integer from 1 to 12; and / or, The antioxidant is a liquid hindered phenolic antioxidant; and / or, The first inorganic filler is nano-calcium carbonate; and / or, The catalyst is at least one of 1,3-dimethylimidazole, Evonik KOSMOS 16, and T131; and / or, The first or second thixotropic agent is fumed silica.

4. The two-component polyurethane adhesive according to claim 1, characterized in that, The first polyisocyanate is one of polymeric MDI, carbodiimide-modified MDI, or liquefied MDI; and / or, The first plasticizer is DIDP, DINP, or IPPP; and / or, The second inorganic filler is ultrafine calcium carbonate, aluminum hydroxide, silica powder, or talc powder, with a particle size of 10-20 μm and a moisture content ≤500 ppm; and / or, The water-absorbing agent is p-toluenesulfonyl isocyanate; and / or... The silane coupling agent is one of the following: γ-glycidoxypropyltrimethoxysilane, 3-(2,3-epoxypropoxy)propylmethyldimethoxysilane, γ-glycidoxypropyltriethoxysilane, β-(3,4-epoxycyclohexyl)-ethyltriethoxysilane, β-(3,4-epoxycyclohexyl)-ethyltrimethoxysilane, and 3-(2,3-epoxypropoxy)propylmethyldiethoxysilane.

5. The two-component polyurethane adhesive according to claim 2, characterized in that, The second polyisocyanate is one of polymeric MDI, carbodiimide-modified MDI, or HDI trimer.

6. The method for preparing the two-component polyurethane adhesive according to any one of claims 1-5, characterized in that, Includes the following steps: S1. Mix hydroxyl-terminated polybutadiene, antioxidant, first inorganic filler, catalyst, and first thixotropic agent to obtain a premix; S2. Mix the premix, chain extender and thickener to obtain component A; S3. Mix the terminal isocyanate prepolymer, the first polyisocyanate, the first plasticizer, the second inorganic filler, the second thixotropic agent, the water-absorbing agent, and the silane coupling agent to obtain component B, wherein the volume ratio of component A to component B is 1:

1.

7. The preparation method according to claim 6, characterized in that, The isocyanate-terminated prepolymer is prepared from the following raw materials in parts by weight: 40-50 parts hydroxyl-terminated polybutadiene, 32-40 parts second polyisocyanate, and 24-26 parts second plasticizer. In step S3, the method for preparing the terminal isocyanate-based prepolymer is as follows: after dehydrating the terminal hydroxyl polybutadiene and the second plasticizer, the terminal hydroxyl polybutadiene, the second plasticizer and the second polyisocyanate are mixed to obtain the terminal isocyanate-based prepolymer.

8. The preparation method according to claim 7, characterized in that, After dehydration treatment of hydroxyl-terminated polybutadiene and the second plasticizer, the moisture content is less than 500 ppm.

9. The preparation method according to claim 7, characterized in that, The hydroxyl-terminated polybutadiene, the second plasticizer, and the second polyisocyanate were mixed and reacted at 70-80°C for 2 hours to obtain the isocyanate-terminated prepolymer.

10. The application of the two-component polyurethane adhesive according to any one of claims 1-5, or the two-component polyurethane adhesive prepared by the preparation method according to claims 6-9, in bonding automotive exterior composite materials.

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