A two-component polyurethane structural adhesive for high-elastic bonding of power batteries

Abstract

The present invention provides a two-component polyurethane structural adhesive for high-elastic bonding of power batteries, which is composed of two components, A and B. The volume ratio of component A to component B is 1:(0.8-1.2); by weight, component A is composed of 50-90 parts of a first polyol, 10-90 parts of a first filler, and 0.01-30 parts of an auxiliary agent; component B is composed of 10-100 parts of an isocyanate prepolymer and 1-70 parts of a second filler; the isocyanate prepolymer is polymerized from the following components: a second polyol, a plasticizer, diphenylmethane diisocyanate, and a catalyst; the first polyol is a mixed polyol composed of at least one selected from polyether polyols with a functionality of 2-4 and polyester polyols with a functionality of 2-4, and at least one small molecule polyol; the second polyol is selected from at least one of polyether polyols with a functionality of 2-4, polyester polyols with a functionality of 2-4, and modified polyols with a functionality of 2-4. The polyurethane structural adhesive of the present invention has the characteristics of low storage modulus, high elongation at break, and high adhesion force.

Description

Technical Field

[0001] The present invention relates to the field of adhesives and coating chemicals, and particularly to a two-component polyurethane structural adhesive for high-elastic bonding of power batteries. Background Art

[0002] According to the statistics of the China Association of Automobile Manufacturers, the exports of new energy vehicles reached 310,000 in 2021, a year-on-year increase of 304.6%. Among them, the exports of new energy passenger vehicles reached 300,000, a year-on-year increase of 329.5%; the exports of new energy commercial vehicles reached 10,000, a year-on-year increase of 59.6%. To achieve the carbon reduction goal, many governments have increased the subsidy for new energy vehicles, and the new energy vehicle markets at home and abroad have developed rapidly. As the power core of new energy vehicles, power batteries have also witnessed a blowout development. In 2021, the production capacity of lithium-ion power batteries in China alone exceeded 137 GWh. New requirements for bonding materials have also been continuously put forward in the aspect of adhesives used for the bonding of power battery PACK structures. The annual production and sales volume of automobiles in China is greater than 25 million.

[0003] Polyurethane adhesives are widely used in the production of lithium-ion power batteries and systems. Such as the thermal conductive adhesive for the water-cooled plate for module heat dissipation inside the battery cell, the pressure-sensitive adhesive coated on the back of the battery cell insulating film, the battery pack housing sealant CTP (cell to pack), etc. The existing polyurethane structural adhesives have excellent adhesiveness to aluminum and PET films of the water-cooled plate, but they generally have disadvantages such as high hardness, high elastic modulus (>1000 MPa), and low elongation rate (≤20%). The power battery PACK is installed on the vehicle and will inevitably be subjected to impacts such as bumps and vibrations during driving. The fixed adhesive for the battery cell also has to withstand various forces such as extrusion, peeling, bending, and fatigue. The reliability of the bonding not only depends on the bonding strength of the adhesive to the substrate, but also the flexibility of the adhesive layer is an important performance index when subjected to impact and vibration. The flexibility of the structural adhesive can be investigated from two aspects: one is the elongation at break; the other is the elastic modulus (storage modulus). The elongation at break is the ratio of the length by which a material elongates in the tensile direction to its original length, dimensionless or expressed as a percentage. It characterizes the deformation ability that the material body can withstand when subjected to external forces. At present, battery manufacturers have expected the elongation at break to reach 100% or even 150%. The elastic modulus (storage modulus) characterizes the ability of the material to store elastic deformation, which is the ratio of stress to strain, with the unit of MPa. Its measurement is often more accurate by using a dynamic thermomechanical analyzer (DMA).

[0004] In the practical application of CTP structural adhesives, high elongation at break and low modulus are desirable properties. The patent with publication number CN109609081 A discloses a polyurethane adhesive for bonding the structure of power battery PACK, which comprises two components A and B with a volume ratio of 1:1. Component A includes: epoxy resin-modified polyol, polyol containing benzene ring, bio-based polyol, crosslinking agent, catalyst, flame retardant, molecular sieve, thixotropic agent; Component B includes polyurethane prepolymer with terminal isocyanate group, isocyanate, flame retardant, adhesion promoter, molecular sieve, thixotropic agent. After the mixing and curing of components A and B, the adhesive force reaches 11.5 - 13.5 MPa (3003AL / 3003AL), and the DMA modulus is 400 - 550 Mpa. The patent with publication number CN 111303820 B discloses a two-component polyurethane structural adhesive for bonding power batteries, which comprises two components A and B with a volume ratio of 1:1 - 2. Component A includes: 40 - 65 parts of polymethylene polyphenyl isocyanate, 30 - 50 parts of aluminum hydroxide, 2 - 5 parts of hydrophobic fumed silica, 0 - 5 parts of plasticizer; Component B includes: 40 - 65 parts of bio-based polyol, 1 - 4 parts of fumed silica, 25 - 50 parts of flame retardant, 1 - 5 parts of adhesion promoter and 0.01 - 0.5 parts of catalyst. After the mixing and curing of components A and B, the adhesive force reaches 10.8 - 12.8 MPa (3003AL / 3003AL), and the DMA modulus is 490 - 760 Mpa. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a two-component polyurethane structural adhesive for high-elasticity bonding of power batteries, which has a lower elastic modulus, excellent elongation at break, and excellent adhesive force to aluminum 3003 alloy, as well as plastic materials such as PET and PC, so as to solve the above-mentioned technical problems existing in the prior art.

[0006] The present invention is implemented by adopting the following technical scheme:

[0007] A two-component polyurethane structural adhesive for high-elasticity bonding of power batteries, which is composed of two components A and B, and the volume ratio of component A to component B is 1:(0.8 - 1.2); calculated by weight, component A is composed of the following materials: 50 - 90 parts of the first polyol, 10 - 90 parts of the first filler, 0.01 - 30 parts of additives; Component B is composed of the following materials: 10 - 100 parts of isocyanate prepolymer, 1 - 70 parts of the second filler;

[0008] The isocyanate prepolymer is polymerized from the following components: the second polyol, plasticizer, diphenylmethane diisocyanate, catalyst;

[0009] The first polyol is a mixed polyol composed of at least one selected from polyether polyols with a functionality of 2-4 and polyester polyols with a functionality of 2-4, and at least one small molecule polyol; preferably, the dosage of the small molecule polyol accounts for 2-10% of the total weight dosage of the first polyol.

[0010] The second polyol is selected from at least one of polyether polyols with a functionality of 2-4, polyester polyols with a functionality of 2-4, and modified polyols with a functionality of 2-4. Preferably, the hydroxyl value of the second polyol is 130-500 mgKOH / g, and the number average molecular weight is 400-4000.

[0011] The polyether polyol refers to an oligomer with an ether bond in the main chain and more than 2 hydroxyl groups at the end or side groups. The polyester polyol refers to an oligomer obtained by polycondensation of dicarboxylic acids and diols, etc.

[0012] Furthermore, the modified polyol is selected from at least one of aliphatic polyether modified polyols with an ester group side chain, castor oil modified polyols, soybean oil modified polyols, aromatic polyester modified polyols, bisphenol A polyether modified polyols, and epoxy resin modified polyols.

[0013] Preferably, the small molecule polyol is a polyol with a functionality of 2-4 and no more than 10 carbon atoms, such as but not limited to ethylene glycol, glycerol, 1,4-butanediol, etc.

[0014] The inventors unexpectedly found that by selecting specific polyols to prepare a novel isocyanate prepolymer with MDI, MDI was modified into an isocyanate containing a flexible molecular chain, so that the cured polyurethane structural adhesive had unexpectedly low storage modulus, high elongation at break, and high adhesion. And due to the use of polyols with appropriate functionality and molecular weight, and a curing agent synthesized as needed, the cured adhesive can exhibit excellent shock resistance. Based on the above findings, the present invention was completed.

[0015] The first filler can be a conventional selection in the art, including but not limited to at least one of aluminum hydroxide, calcium carbonate, silica powder, spherical alumina, carbon black, titanium dioxide, fumed silica, angular alumina, and tabular corundum. Preferably, the first filler is selected from at least one of aluminum hydroxide, silica powder, lemon yellow, carbon black, and fumed silica. Preferably, the particle size D50 of the first filler is distributed in 2-100 um.

[0016] Various common additives in the art can be added to component A, including but not limited to plasticizers, anti-settling agents, antioxidants, dispersants, catalysts, etc.

[0017] As a preferred technical solution, the preparation method of Component A includes the following steps: Add the first polyol into a stirring kettle, heat it to 120°C, evacuate and defoam with stirring for 1 - 2 h, cool it to 25 - 50°C, then add the first filler and additives, and stir under vacuum until evenly mixed to obtain Component A.

[0018] As a preferred technical solution, the preparation method of the isocyanate prepolymer includes the following steps: Mix the second polyol and an appropriate amount of plasticizer, heat it to 120 - 130°C, and stir under vacuum for 2 - 3 h; cool it to 25 - 40°C, then add diphenylmethane diisocyanate according to the stoichiometry with the NCO content in the reaction system being 15 - 35%, add an appropriate amount of catalyst, heat it to 60 - 80°C, stir under vacuum for 3 - 4 h, and cool it to room temperature to obtain the isocyanate prepolymer. The viscosity of the product is 2000 - 6000 cps (25°C), it is a light yellow translucent liquid, and has the characteristics of high adhesion and a high proportion of flexible molecular chain groups.

[0019] The plasticizer can be a commonly used component in the art, such as but not limited to dioctyl terephthalate, and its dosage can be adjusted according to actual needs. As a preferred embodiment of the present invention, the dosage of the plasticizer is 1 - 5% of the weight dosage of the second polyol.

[0020] The catalyst can be a commonly used component in the art, such as but not limited to dibutyltin dilaurate, and its dosage can be adjusted according to the specific raw materials and dosage ratios selected for the prepolymerization reaction. As a preferred embodiment of the present invention, the dosage of the catalyst is 0.01 - 0.05% of the weight dosage of the second polyol.

[0021] In Component B, the second filler can be a conventional selection in the art, including but not limited to at least one of aluminum hydroxide, calcium carbonate, silica powder, spherical alumina, carbon black, titanium dioxide, fumed silica, angular alumina, tabular corundum. Preferably, it is at least one of cobalt blue, titanium dioxide, silica powder, and fumed silica.

[0022] The preparation method of Component B includes the following steps: Add the isocyanate prepolymer and the second filler into a stirring kettle, and stir evenly under vacuum to obtain Component B.

[0023] The two-component polyurethane structural adhesive of the present invention for high-elastic bonding of power batteries, its preparation method includes the following steps: Mix Component A and Component B evenly according to a volume ratio of 1:(0.8 - 1.2), and obtain the product after complete curing.

[0024] Through the synthesis of a novel isocyanate prepolymer, the present invention modifies MDI into an isocyanate containing a flexible molecular chain, thereby endowing the cured polyurethane structural adhesive with the characteristics of low storage modulus, high elongation at break, and high adhesion. Due to the use of polyols with appropriate functionality and molecular weight, as well as a curing agent synthesized as needed, the cured adhesive can exhibit excellent vibration resistance. Moreover, the manufacturing and construction processes are simple; the volume shrinkage rate after the components react is low, and it will not deform the adhered workpieces; no solvent is added, the odor is extremely low, and it is harmless to the operators and the construction environment; it is environmentally friendly and conducive to promotion. Detailed Embodiments

[0025] The following description is used to disclose the present invention so that those skilled in the art can implement the present invention. The preferred embodiments in the following description are only examples and do not limit the scope of the present invention. Those skilled in the art can think of other obvious variations. The basic principles of the present invention defined in the following description can be applied to other embodiments, variants, improvements, equivalent solutions, and other technical solutions that do not depart from the spirit and scope of the present invention.

[0026] In the present invention, if the instruments or raw materials are not specified by the manufacturer, they are all conventional commercial instruments or raw materials.

[0027] Among them:

[0028] The polyester diol uses the product of Huafeng manufacturer with the grade of PE-1410;

[0029] The polyether diol uses the product of Yinuowei manufacturer with the grade of S215H;

[0030] The polyether triol uses the product of Yinuowei manufacturer with the grade of C310;

[0031] The polyether tetrol uses the product of Yinuowei manufacturer with the grade of F414;

[0032] The modified castor oil polyol uses the product of Jingrihua manufacturer with the grade of A1300;

[0033] The aliphatic polyether-modified polyol containing an ester group side chain uses the product of Jingrihua manufacturer with the grade of DA21;

[0034] The aromatic polyester polyol uses the product of Stepan manufacturer with the grade of PS-1752;

[0035] The anti-settling agent uses the product of Arkema manufacturer with the grade of CRAYVALLAC 60P;

[0036] The antioxidant uses the product of BASF manufacturer with the grade of Irganox 1010;

[0037] The dispersant uses the product of BYK manufacturer with the grade of W996;

[0038] The catalyst used is dibutyltin dilaurate from Aladdin.

[0039] For the detection indexes involved in the embodiments of the present invention, if not mentioned, the conventional detection methods in the art are used for detection. Among them:

[0040] The Shore hardness is detected according to the national standard GB / T 531.1;

[0041] The lap shear strength is detected according to the standard ISO4587;

[0042] The tensile strength and elongation at break are detected according to the national standard GB / T 1040.1;

[0043] The DMA modulus is detected according to the American standard ASTM D7028.

[0044] Example 1

[0045] Preparation of Component A:

[0046] 1) Add 10 parts of polyester diol, 60 parts of polyether triol, 8 parts of polyether tetrol, 2 parts of dioctyl terephthalate, and 3 parts of ethylene glycol into a stirring kettle, conduct vacuum defoaming, heat to 120 °C, stir and mix for 2 h, and then cool to 50 °C;

[0047] 2) Add 50 parts of aluminum hydroxide, 10 parts of silica powder, 0.3 part of lemon yellow, 0.1 part of anti-settling agent, 0.02 part of antioxidant, 0.01 part of dispersant, and 0.01 part of catalyst, conduct vacuum defoaming, and stir and mix for 2 h. Keep at 50 °C, add 1 part of fumed silica, evacuate to -0.098 MPa, and stir and mix for 2 h;

[0048] 3) Cool to room temperature, discharge, and obtain Component A.

[0049] Preparation of the isocyanate prepolymer in Component B:

[0050] 1) Add 10 parts of polyether triol, 80 parts of polyether diol, 30 parts of polyester diol, and 2 parts of dioctyl terephthalate into a stirring kettle, heat to 120 °C, evacuate and stir for 2.5 h, and then cool to 40 °C;

[0051] 2) Add 250 parts of MDI and 0.02 part of dibutyltin dilaurate, raise the temperature of the system to about 65 °C, evacuate and stir and react for 3 h;

[0052] 3) Cool and discharge to obtain the isocyanate prepolymer.

[0053] Preparation of Component B:

[0054] 1) Add 100 parts of the above prepolymer, 0.03 part of cobalt blue, and 30 parts of silica powder into a stirring kettle; evacuate and stir for 1 h;

[0055] 2) Add 20 parts of fumed silica, evacuate and stir for 2 h;

[0056] 3) Discharge the material to obtain Component B.

[0057] Mix Component A and Component B evenly according to a volume ratio of 1:1 to obtain a high-elastic bonding polyurethane structural adhesive.

[0058] Apply the evenly mixed high-elastic bonding polyurethane structural adhesive onto the surface of an AL / AL3003 substrate within 10 min. The substrate has been pre-surface treated with absolute ethanol. After applying the adhesive, leave it to stand at room temperature (25 °C) and 50% RH for 168 h to achieve the best bonding effect. The tensile shear strength test results are 14 - 17 MPa, the elongation at break is 100 - 120%, and the elastic modulus is 400 MPa.

[0059] Example 2

[0060] Preparation of Component A:

[0061] 1) Add 10 parts of polyester diol, 70 parts of polyether triol, 2 parts of dioctyl terephthalate, and 5 parts of 1,4-butanediol into a stirring kettle, perform vacuum degassing, heat to 120 °C, stir and mix for 2 h, and then cool to 50 °C;

[0062] 2) Add 60 parts of aluminum hydroxide, 10 parts of silica powder, 0.3 part of carbon black, 0.1 part of anti-settling agent, 0.02 part of antioxidant, 0.01 part of dispersant, and 0.01 part of catalyst, perform vacuum degassing, and stir and mix for 2 h. Keep at 50 °C, add 1 part of fumed silica, evacuate to -0.098 MPa, and stir and mix for 2 h;

[0063] 3) Cool to room temperature and discharge the material to obtain Component A.

[0064] Preparation of the isocyanate prepolymer in Component B:

[0065] 1) Add 20 parts of polyether diol, 80 parts of modified castor oil polyol, and 2 parts of dioctyl terephthalate into a stirring kettle, heat to 120 °C, evacuate and stir for 2.5 h, and then cool to 40 °C;

[0066] 2) Add 270 parts of MDI and 0.02 part of dibutyltin dilaurate, raise the temperature of the system to about 65 °C, evacuate and stir and react for 3 h;

[0067] 3) Cool and discharge the material to obtain the isocyanate prepolymer.

[0068] Preparation of Component B:

[0069] 1) Add 100 parts of the above prepolymer, 1 part of titanium dioxide, and 30 parts of silica powder into a stirring kettle; evacuate and stir for 1 h;

[0070] 2) Add 20 parts of fumed silica, evacuate and stir for 2 h;

[0071] 3) Discharge the material to obtain Component B.

[0072] Mix Component A and Component B evenly according to a volume ratio of 1:1 to obtain a high-elastic adhesive polyurethane structural adhesive.

[0073] Apply the evenly mixed high-elastic adhesive polyurethane structural adhesive onto the surface of an AL / AL3003 substrate within 10 min. The substrate has been pre-surface treated with absolute ethanol. After applying the adhesive, leave it standing at room temperature (25 °C) and 50% RH for 168 h to achieve the best bonding effect. The tensile shear strength test results are 12 - 14.5 MPa, the elongation at break is 120 - 150%, and the elastic modulus is 370 MPa.

[0074] Example 3

[0075] Preparation of Component A:

[0076] 1) Add 10 parts of polyester diol, 70 parts of polyether triol, 2 parts of dioctyl terephthalate, and 5 parts of 1,4-butanediol, conduct vacuum degassing, heat to 120 °C, stir and mix for 2 h, and then cool to 50 °C;

[0077] 2) Add 60 parts of aluminum hydroxide, 10 parts of silica powder, 0.3 part of carbon black, 0.1 part of anti-settling agent, 0.02 part of antioxidant, 0.01 part of dispersant, and 0.01 part of catalyst, conduct vacuum degassing, and stir and mix for 2 h. Keep at 50 °C, add 1 part of fumed silica, evacuate to -0.098 MPa, and stir and mix for 2 h;

[0078] 3) Cool to room temperature and discharge the material to obtain Component A.

[0079] Preparation of the isocyanate prepolymer in Component B:

[0080] 1) Add 20 parts of polyether diol, 50 parts of aliphatic polyether modified polyol with an ester group side chain, 30 parts of aromatic polyester polyol, and 2 parts of dioctyl terephthalate into a stirring kettle, heat to 120 °C, evacuate and stir for 2.5 h, and then cool to 40 °C;

[0081] 2) Add 200 parts of MDI and 0.02 part of dibutyltin dilaurate, raise the temperature of the system to about 65 °C, evacuate and stir and react for 3 h;

[0082] 3) Cool and discharge the material to obtain the isocyanate prepolymer.

[0083] Preparation of Component B:

[0084] 1) Add 100 parts of the above prepolymer, 1 part of titanium dioxide, and 30 parts of silica powder into a stirring kettle; evacuate and stir for 1 h;

[0085] 2) Add 20 parts of fumed silica, evacuate and stir for 2 h;

[0086] 3) Discharge the material to obtain Component B.

[0087] Mix Component A and Component B evenly according to a volume ratio of 1:1 to obtain a high-elasticity bonding polyurethane structural adhesive.

[0088] Apply the evenly mixed high-elasticity bonding polyurethane structural adhesive onto the surface of an AL / AL3003 substrate within 10 min. The substrate has been pre-surface-treated with absolute ethanol. After applying the adhesive, leave it to stand at room temperature of 25°C and 50% RH for 168 h to achieve the best bonding effect. The tensile shear strength test results are 15 - 17 MPa, the elongation at break is 90 - 110%, and the elastic modulus is 450 MPa.

[0089] Comparative Example 1

[0090] 1) Preparation of Component A: Take 15 kg of epoxy resin polyol, 20 kg of phthalic anhydride polyester polyol, 5 kg of castor oil, 15 kg of castor oil-modified polyol, 0.5 kg of 4.6-functional rigid foam polyether polyol, 25 kg of nitrogen-phosphorus halogen-free flame retardant, 8 kg of aluminum hydroxide, 1 kg of fumed silica, 4.5 kg of molecular sieve, and 0.05 kg of bismuth neodecanoate, and stir them evenly at a high speed of 1200 r / min. After stirring for 2 h, obtain Component A. The preparation method of the epoxy resin polyol is as follows: Mix 30 kg of bisphenol F diglycidyl ether epoxy resin and 5.5 kg of diphenylmethane diisocyanate, mix and react at a stirring speed of 300 r / min and a temperature of 210°C for 1 h, cool down to 45°C, add 50 kg of polyoxypropylene triol with a molecular weight of 1000, keep stirring and slowly heat up to 70°C, and after reacting for 2 h, cool down to room temperature to obtain the epoxy resin polyol.

[0091] 2) Preparation of Component B: 65 kg of terminal isocyanate group polyurethane prepolymer, 10 kg of polymeric MDI, 20 kg of nitrogen-phosphorus halogen-free flame retardant, 5 kg of molecular sieve, 0.5 kg of fumed silica, and 0.1 kg of adhesion promoter BYK4500 were evenly dispersed by high-speed stirring at a speed of 1200 r / min for 2 h to obtain Component B. The preparation method of the terminal isocyanate group polyurethane prepolymer is as follows: 100 kg of polyoxypropylene glycol with a molecular weight of 2000 was heated to 110 °C and evacuated to -0.098 MPa, stirred at a speed of 450 r / min for 2 h to dehydrate, then cooled to 45 °C, 120 kg of liquefied MDI was added in proportion, and after the reaction temperature was stabilized, the temperature was adjusted to 70 °C, stirred for 2 h, and then cooled to room temperature to obtain the terminal isocyanate group polyurethane prepolymer.

[0092] The Component A and Component B were mixed evenly in a certain proportion to obtain the structural adhesive of Comparative Example 1.

[0093] Comparative Example 2

[0094] 1) Preparation of Component A: 450 g of polymethylene polyphenyl isocyanate PM200, 490 g of aluminum hydroxide, 25 g of Wacker H17 hydrophobic silica, and 35 g of tricresyl phosphate were added to a planetary mixer and stirred and dispersed for 3 h to obtain Component A with a viscosity of about 23 Pa·s.

[0095] 2) Preparation of Component B: 650 g of Sovermol 1092 polyol and 280 g of nitrogen-phosphorus based flame retardant were added to a planetary mixer, dehydrated under vacuum at 110 °C for 1 h, and then cooled to 60 °C. Then 10 g of Wacker N20 hydrophilic silica, 50 g of adhesion promoter, and 2 g of bismuth isooctanoate catalyst were added, and stirred under vacuum for 3 h to obtain Component B. The viscosity was about 11 Pa·s.

[0096] The Component A and Component B were mixed evenly at a volume ratio of 1:1 to obtain the structural adhesive of Comparative Example 2.

[0097] Table 1 shows the performance indexes of the polyurethane structural adhesives prepared according to the embodiments of the present invention. Among them, the lap shear strength refers to the strength when 3003AL / 3003AL is adhered and stretched to failure. The tensile strength refers to the tensile strength of the cured adhesive body. The DMA modulus is the ratio of stress to strain obtained by using the force in the elastic deformation range of the rubber strip at 25 °C and 1 Hz.

[0098] Table 1 Comparison of the Performance of Polyurethane Structural Adhesives

[0099]

[0100]

[0101] Compared with the polyurethane structural adhesive prepared in Comparative Example 1, the polyurethane structural adhesive of the present invention has the properties of high bonding strength, moderate hardness, high bulk strength and elongation at break, and low storage modulus.

[0102] Those skilled in the art should understand that the above embodiments are only examples and do not limit the present invention. The object of the present invention has been fully and effectively achieved. The function and structural principle of the present invention have been shown and explained in the embodiments. Without departing from the said principle, any deformation or modification can be made to the embodiments of the present invention.

Claims

1. A two-component polyurethane structural adhesive for high-elastic bonding of power batteries, characterized in that, it consists of two components, A and B, and the volume ratio of component A to component B is 1:(0.8 - 1.2); by weight, component A consists of the following materials: 50 - 90 parts of the first polyol, 10 - 90 parts of the first filler, 0.01 - 30 parts of additives; component B consists of the following materials: 10 - 100 parts of isocyanate prepolymer, 1 - 70 parts of the second filler; the isocyanate prepolymer is polymerized from the following components: the second polyol, a plasticizer, diphenylmethane diisocyanate, a catalyst; the first polyol is a mixed polyol composed of a polyether polyol selected from those with functionality 2 - 4, a polyester diol PE - 1410, and at least one small molecule polyol; among them, the polyether polyol is selected from polyether diol S215H, polyether triol C310, polyether tetrol F414; the second polyol is selected from at least one of polyether polyols with functionality 2 - 4 and polyester diol PE - 1410, and the hydroxyl value of the second polyol is 130 - 500mgKOH / g, and the number average molecular weight is 400 - 4000; among them, the polyether polyol is selected from polyether diol S215H, polyether triol C310, polyether tetrol F414.

2. The two-component polyurethane structural adhesive according to claim 1, characterized in that, the dosage of the small molecule polyol accounts for 2 - 10% of the total weight dosage of the first polyol.

3. The two-component polyurethane structural adhesive according to claim 1, characterized in that, the first filler is selected from at least one of aluminum hydroxide, silica powder, lemon yellow, carbon black, fumed silica; the second filler is selected from at least one of cobalt blue, titanium dioxide, silica powder, fumed silica.

4. The two-component polyurethane structural adhesive according to claim 3, characterized in that, the particle size D50 of the first filler and the second filler is distributed in 2 - 100um.

5. The two-component polyurethane structural adhesive according to claim 1, characterized in that, the preparation method of component A includes the following steps: adding the first polyol to a stirring kettle, heating to 120°C, and performing vacuum defoaming and stirring for 1 - 2h, cooling to 25 - 50°C, then adding the first filler and additives, and performing vacuum stirring until evenly mixed to obtain component A.

6. The two-component polyurethane structural adhesive according to claim 1, characterized in that, the preparation method of the isocyanate prepolymer includes the following steps: mixing the second polyol and an appropriate amount of plasticizer, heating to 120 - 130°C, and performing vacuum stirring for 2 - 3h; cooling to 25 - 40°C, then adding diphenylmethane diisocyanate according to the stoichiometry with the NCO content in the reaction system being 15 - 35%, adding an appropriate amount of catalyst, heating to 60 - 80°C, performing vacuum stirring for 3 - 4h, and cooling to room temperature to obtain the isocyanate prepolymer.

7. The two-component polyurethane structural adhesive according to claim 6, characterized in that, The preparation method of Component B comprises the following steps: adding the isocyanate prepolymer and the second filler into a stirring kettle, and stirring evenly under vacuum to obtain Component B; the plasticizer is dioctyl terephthalate, and the catalyst is dibutyltin dilaurate.

8. The two-component polyurethane structural adhesive according to claim 1, characterized in that its preparation method comprises the following steps: mixing Component A and Component B evenly according to a volume ratio of 1:(0.8 - 1.2), and obtaining a product after complete curing.

Images