Bi-component polyurethane heat-conducting structural adhesive that can be easily adhered to blue film, and preparation method therefor

Abstract

The present invention relates to the technical field of bi-component polyurethane structural adhesives and provides a bi-component polyurethane heat-conducting structural adhesive that can be easily adhered to a blue film, and a preparation method therefor. The bi-component polyurethane heat-conducting structural adhesive comprises a polyol component and an isocyanate component, wherein the polyol component comprises a polyether polyol, a bio-based oily polyol, an isocyanate-based silane coupling agent, a first heat-conducting filler, a water absorbent and a catalyst; and one end of the isocyanate-based silane coupling agent is terminated by an isocyanate group, and the other end thereof is terminated by a siloxane group. The mass ratio of the isocyanate-based silane coupling agent to the liquid material in the polyol component is less than 4 wt%. In the polyol component, the isocyanate-based silane coupling agent and the polyol are subjected to a condensation reaction to generate a siloxane-terminated telechelic resin. The isocyanate component comprises an isocyanate-terminated prepolymer, a second heat-conducting filler and a wetting dispersant. The present invention solves the problem of the reduced adhesive property of the existing heat-conducting structural adhesive caused by a large amount of heat-conducting fillers contained in the heat-conducting structural adhesive.

Description

Two-component polyurethane thermal conductive structural adhesive easy to bond blue film and preparation method

[0001] Cross-references

[0002] This application claims priority to Chinese application No. 202311817941X, filed on December 26, 2023. The contents of the above application are incorporated herein by reference. Technical Field

[0003] The invention relates to the technical field of two-component polyurethane structural adhesives, in particular to a two-component polyurethane thermal conductive structural adhesive that is easy to bond blue films and a preparation method thereof. Background Art

[0004] The outside of the aluminum shell of new energy batteries is often covered with an insulating film. During the bonding process, the insulating film often debonds. The main reason is that the outer surface of the insulating film is coated with an anti-stick coating, which is also called a battery cell blue film. For example, the Chinese patent with publication number CN105751640A describes a battery cell blue film. Referring to Figure 1, the battery cell blue film 100 includes an anti-stick coating 10, a first PET polyester film 20, a first blue acrylic resin 30, a second PET polyester film 40 and a second blue acrylic resin 50. Currently, most anti-stick coatings are silicone-based. Therefore, on the new energy PACK assembly line, the battery cell blue film usually needs to be surface treated to improve the bonding effect.

[0005] Two-component polyurethane thermally conductive structural adhesives are commonly used to bond the insulation film and liquid cooling plate of battery cells. The commonly used high-thermal-conductivity two-component polyurethane thermally conductive structural adhesives on the market, due to the inclusion of a large amount of thermally conductive filler, are not suitable for bonding to the battery cell blue film containing a release coating (anti-stick coating). Improving the bonding strength of two-component polyurethane thermally conductive structural adhesives to the battery cell blue film is of great significance to improving the overall reliability of the battery.

[0006] Currently, the commonly used method is to change the polarity of the two-component polyurethane thermal conductive structural adhesive by adding a low-polarity resin to improve the bonding strength to the battery cell blue film. The Chinese patent with publication number CN109593507A records the use of low-polarity resin end-hydroxyl hydrogenated polybutadiene to improve the bonding strength of the two-component polyurethane adhesive to the battery cell blue film; the Chinese patent with publication number CN111534268A uses end-hydroxyl polybutadiene or dimer acid-modified polyester polyol to improve the bonding strength of the two-component polyurethane adhesive to the battery cell blue film.

[0007] The existing technology uses the addition of low-polarity polyols to improve the adhesion of two-component polyurethane thermal conductive structural adhesive to the battery core blue film. However, the Tg value of low-polarity polyols is very low. For example, the Tg value of terminal hydroxyl polybutadiene polyol is -70°C, which will greatly affect the Tg value of the two-component polyurethane thermal conductive structural adhesive, thereby causing the bonding performance of the two-component polyurethane thermal conductive structural adhesive to hard materials such as metal to decrease, making the two-component polyurethane thermal conductive structural adhesive less universal in the bonding application of battery core blue film and aluminum liquid cooling plate, thus losing sight of one thing while focusing on another.

[0008] In addition, neither hydroxy-terminated polybutadiene nor dimer acid-modified polyester polyols have been widely popularized in China. The two polyols currently on the market are POLY BD under Total (now sold to Pacific Avenue Capital) and Cargill's Priplast series products. The current market prices of these two products range from 60 to 120 yuan / kg, which is much higher than the 10 to 50 yuan / kg price of traditional polyurethane polyol resins. The high price of low-polarity polyols limits the widespread use of two-component polyurethane thermal conductive structural adhesives containing low-polarity polyols.

[0009] Therefore, there is an urgent need to develop a two-component polyurethane thermal conductive structural adhesive that is easy to bond blue film and a preparation method thereof to solve the above problems.

[0010] Summary of the Invention

[0011] The purpose of the present invention is to provide a two-component polyurethane thermal conductive structural adhesive that is easy to bond blue film and a preparation method thereof, which solves the problem of effectively improving the bonding performance of existing thermal conductive structural adhesives to insulating films, aluminum substrates, etc. at a lower cost.

[0012] To achieve the above-mentioned object, in a first aspect, the present invention provides a two-component polyurethane thermal conductive structural adhesive that is easy to bond to a blue film, wherein the two-component polyurethane thermal conductive structural adhesive comprises a polyol component and an isocyanate component, calculated in parts by mass;

[0013] The polyol component comprises 70-90 parts of a polyether polyol, 100-200 parts of a bio-based oily polyol, 1-5 parts of an isocyanate-based silane coupling agent, 600-800 parts of a first thermally conductive filler, 20-36 parts of a water absorbent, and 0.16-0.24 parts of a catalyst; one end of the isocyanate-based silane coupling agent is capped with an isocyanate group and the other end is capped with a siloxane group, and the mass ratio of the isocyanate-based silane coupling agent to the liquid material in the polyol component is less than 4wt%; in the polyol component, the isocyanate-based silane coupling agent and the polyol undergo a condensation reaction to form a siloxane-capped telechelic resin;

[0014] The isocyanate component includes 140-180 parts of terminal isocyanate prepolymer, 750-900 parts of second thermal conductive filler and 2-10 parts of wetting and dispersing agent.

[0015] Optionally, the isocyanate silane coupling agent is one or a combination of isocyanate propyl triethoxy silane and isocyanate propyl trimethoxy silane.

[0016] Optionally, the molecular weight of the polyether polyol in the polyol component is 400-2000.

[0017] Optionally, the bio-based oily polyol is one or more of soybean oil, castor oil, palm oil, hydrogenated castor oil, and modified castor oil.

[0018] Optionally, the isocyanate-terminated prepolymer is produced by reacting a polyether polyol having a molecular weight of 2000-4000 with an isocyanate monomer, and the NCO content of the isocyanate-terminated prepolymer is 15-25%.

[0019] Optionally, the isocyanate monomer is one or two or more of diphenylmethane diisocyanate, dicyclohexylmethane diisocyanate, toluene diisocyanate, isophorone diisocyanate, and hexamethylene isocyanate.

[0020] Optionally, the mass ratio of the polyether polyol with a molecular weight of 2000-4000 to the isocyanate monomer is 1:(3-4).

[0021] Optionally, the polyol component and / or the isocyanate component further comprises a color paste.

[0022] In a second aspect, the present invention provides a method for preparing a two-component polyurethane thermally conductive structural adhesive, comprising the following steps:

[0023] Preparation of polyol component: prepare raw materials according to the ratio, add the raw materials required for the polyol component into a blender, evacuate the mixture, and stir evenly to obtain the polyol component;

[0024] Preparation of the isocyanate component: first prepare an isocyanate-terminated prepolymer; then take a corresponding mass fraction of the isocyanate-terminated prepolymer and mix it with the raw materials required for the isocyanate component, evacuate the mixture, and stir evenly to obtain the isocyanate component;

[0025] The prepared polyol component and the isocyanate component are mixed in a volume ratio of 1:1 for use.

[0026] Optionally, the isocyanate-terminated prepolymer is prepared in the following manner: a polyether polyol with a molecular weight of 2000-4000 is heated to 115-125° C., stirred and evacuated to a negative pressure state, dehydrated, cooled to 65-75° C., filled with nitrogen, added with isocyanate monomer, heated to 75-85° C., kept warm for reaction for 3-4 hours, and cooled to 55-65° C. while stirring to obtain the isocyanate-terminated prepolymer.

[0027] The beneficial effects of the present invention include:

[0028] 1. The two-component polyurethane thermal conductive structural adhesive of the present application changes the polarity of the polyurethane resin generated with the polyol by adding an isocyanate-based silane coupling agent, effectively improving the adhesion to the blue film of the battery cell. The formula does not contain high-cost low-grade resins, and the cost is controlled at a low level.

[0029] 2. Since a small amount of isocyanate-based silane coupling agent is added to the two-component polyurethane thermal conductive structural adhesive of the present application, the storage stability of the polyol component can be maintained and the Tg value of the two-component polyurethane thermal conductive structural adhesive will not be changed.

[0030] 3. The two-component polyurethane thermal conductive structural adhesive of the present application does not require plasma treatment to bond the blue film of the battery core and can achieve ideal (in line with industry standards) bonding strength.

[0031] 4. The two-component polyurethane thermal conductive structural adhesive of the present application improves the bonding strength to the blue film of the battery cell while maintaining the bonding strength to the aluminum substrate, and has a wide range of applications. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] FIG1 is a schematic diagram of the structure of a blue film of a battery cell in the prior art;

[0033] FIG2 is a schematic flow chart of a method for preparing a two-component polyurethane thermally conductive structural adhesive according to the present invention. DETAILED DESCRIPTION

[0034] To make the objectives, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions in the embodiments of the present invention are clearly and completely described below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0035] The invention improves the adhesion of the two-component polyurethane heat-conductive structural adhesive to the insulating film by adding an isocyanate silane coupling agent, and can achieve good adhesion even without plasma treatment of the insulating film.

[0036] The present invention provides a two-component polyurethane thermal conductive structural adhesive that is easy to bond blue film. The two-component polyurethane thermal conductive structural adhesive includes a polyol component and an isocyanate component, calculated in parts by mass;

[0037] The polyol component comprises 70-90 parts of a polyether polyol, 100-200 parts of a bio-based oily polyol, 1-5 parts of an isocyanate-based silane coupling agent, 600-800 parts of a first thermally conductive filler, 20-36 parts of a water absorbent, and 0.16-0.24 parts of a catalyst; one end of the isocyanate-based silane coupling agent is capped with an isocyanate group and the other end is capped with a siloxane group, and the mass ratio of the isocyanate-based silane coupling agent to the liquid material in the polyol component is less than 4wt%; in the polyol component, the isocyanate-based silane coupling agent and the polyol undergo a condensation reaction to form a siloxane-capped telechelic resin;

[0038] The isocyanate component includes 140-180 parts of terminal isocyanate prepolymer, 750-900 parts of second thermal conductive filler and 2-10 parts of wetting and dispersing agent.

[0039] In some embodiments of the present invention, a portion of the hydroxyl groups at the ends of the polyol are capped by the isocyanate silane coupling agent to generate a siloxane-terminated telechelic resin. The specific production route is as follows:

[0040] In some embodiments of the present invention, the liquid material in the polyol component consists of polyether polyol and bio-based oily polyol.

[0041] In some embodiments of the present invention, the first thermally conductive filler is composed of the following raw materials in parts by mass: 320-480 parts of large-particle thermally conductive filler and 290-450 parts of small-particle thermally conductive filler, the particle size range of the large-particle thermally conductive filler is 40-60 microns, and the particle size range of the small-particle thermally conductive filler is 6-10 microns.

[0042] In some embodiments of the present invention, the second thermally conductive filler is composed of the following raw materials in parts by mass: 365-555 parts of large-particle thermally conductive filler, 180-275 parts of small-particle thermally conductive filler and 110-166 parts of ultrafine powder thermally conductive filler, the particle size range of the large-particle thermally conductive filler is 40-60 microns, the particle size range of the small-particle thermally conductive filler is 6-10 microns, and the particle size range of the ultrafine powder thermally conductive filler is 0.8-1.2 microns.

[0043] In some embodiments of the present invention, the isocyanate silane coupling agent is one or a combination of isocyanate propyl triethoxy silane and isocyanate propyl trimethoxy silane.

[0044] In some embodiments of the present invention, the molecular weight of the polyether polyol in the polyol component is 400-2000.

[0045] In some specific embodiments of the present invention, the bio-based oily polyol is one or more of soybean oil, castor oil, palm oil, hydrogenated castor oil, and modified castor oil.

[0046] In some specific embodiments of the present invention, the isocyanate-terminated prepolymer is produced by reacting a polyether polyol having a molecular weight of 2000-4000 with an isocyanate monomer, and the NCO content of the isocyanate-terminated prepolymer is 15-25%. Specifically, the NCO content of the isocyanate-terminated prepolymer = the mass of the isocyanate groups contained in the isocyanate-terminated prepolymer / the mass of the isocyanate-terminated prepolymer × 100%.

[0047] In some embodiments of the present invention, the isocyanate monomer is one or more of diphenylmethane diisocyanate, dicyclohexylmethane diisocyanate, toluene diisocyanate, isophorone diisocyanate, and hexamethylene isocyanate. Specifically, the diphenylmethane diisocyanate is abbreviated as MDI, the dicyclohexylmethane diisocyanate is abbreviated as HMDI, the toluene diisocyanate is abbreviated as TDI, the isophorone diisocyanate is abbreviated as IPDI, and the hexamethylene isocyanate is abbreviated as HDI.

[0048] In some specific embodiments of the present invention, the mass ratio of the polyether polyol with a molecular weight of 2000-4000 to the isocyanate monomer is 1:(3-4).

[0049] In some embodiments of the present invention, the polyol component and / or the isocyanate component further comprises a color paste.

[0050] The present invention provides a method for preparing a two-component polyurethane thermal conductive structural adhesive, referring to FIG2 , comprising the following steps:

[0051] S1: Preparation of polyol component: prepare raw materials according to the ratio, add the raw materials required for the polyol component into a blender, evacuate the mixture, and stir evenly to obtain the polyol component;

[0052] S2: Preparation of isocyanate component: first prepare an isocyanate-terminated prepolymer; then take a corresponding mass fraction of the isocyanate-terminated prepolymer and mix it with the raw materials required for the isocyanate component, evacuate the mixture, and stir evenly to obtain the isocyanate component;

[0053] S3: mixing the prepared polyol component and the isocyanate component in a volume ratio of 1:1.

[0054] In some embodiments of the present invention, the isocyanate-terminated prepolymer is prepared as follows: a polyether polyol with a molecular weight of 2000-4000 is heated to 115-125°C, stirred while evacuating to a negative pressure state, dehydrated, cooled to 65-75°C, filled with nitrogen, added with isocyanate monomer, heated to 75-85°C, kept warm for reaction for 3-4 hours, and cooled to 55-65°C while stirring to obtain the isocyanate-terminated prepolymer.

[0055] The raw materials involved in Examples 1-3 of the present invention and the comparative examples are: polyether polyol, sourced from Shandong Bluestar Dongda Co., Ltd., with the brands MN700 (molecular weight 700) and MN-3050D (molecular weight 3000); modified castor oil, sourced from Ito Corporation of Japan, with the brand AC-009; γ-glycidyloxypropyltrimethoxysilane, sourced from Shanghai Hongshun Biotechnology Co., Ltd., with the brand KH560, which is a common epoxy silane coupling agent; the isocyanate silane coupling agent: 3-isocyanatepropyltriethoxysilane, sourced from Momentive, with the brand Silquest A-1310, abbreviated as IPTES in English; 3-isocyanatepropyltrimethoxysilane, sourced from Momentive, with the brand Silquest Y-5187, abbreviated as IPTMS in English; the catalyst is dibutyltin dilaurate (abbreviated as T12), which is sourced from Shandong Maofa Chemical; the thermal conductive filler can be aluminum hydroxide. For large-particle thermal conductive fillers, Shanghai Jiaqi Chemical's model H-50C (D50 is 50 microns) aluminum hydroxide can be selected; for small-particle thermal conductive fillers, Shanghai Jiaqi Chemical's model H-08C (D50 is 8 microns) aluminum hydroxide can be selected; for ultrafine powder thermal conductive fillers, Shanghai Jiaqi Chemical's model H-01XP (D50 is 1 micron) aluminum hydroxide can be selected; the wetting and dispersing agent is BYK-W 9010, the water absorbent is 4A molecular sieve activated powder, and the yellow paste and blue paste are commercially available conventional ones.

[0056] Example 1

[0057] The polyol components include: 80 parts of MN700, 116 parts of AC-009, 1 part of IPTES, 400 parts of H-50C, 370 parts of H-08C, 2.8 parts of yellow paste, 30 parts of 4A molecular sieve activated powder and 0.2 parts of T12;

[0058] The isocyanate component includes: 165 parts of prep-1, 460 parts of H-50C, 228 parts of H-08C, 138 parts of H-01XP, 5 parts of BYK-W 9010 and 4 parts of blue paste;

[0059] Preparation of polyol component: Add MN700, AC-009, IPTES, H-50C, H-08C, yellow paste, 4A molecular sieve activated powder and T12 into a blender, evacuate the mixture, and stir to disperse uniformly to obtain the polyol component;

[0060] Preparation of isocyanate-terminated prepolymer prep-1: 39 g of MN-3050D was heated to 120°C, evacuated to -0.085 MPa, stirred and dehydrated for 2 h, then cooled to 70°C, broken the vacuum with nitrogen, added 126 g of HMDI, and heated to 80°C. The reaction was kept at this temperature for 3.5 h, then cooled to 60°C while stirring, sealed and stored for later use.

[0061] Preparation of isocyanate component: Add prep-1, H-50C, H-08C, H-01XP, BYK-W9010 and blue paste into a blender, evacuate the mixture, and stir to disperse uniformly to obtain the isocyanate component;

[0062] The obtained polyol component and isocyanate component were placed into a rubber tube with a volume ratio of 1:1 and stored at room temperature.

[0063] Example 2

[0064] The polyol components include: 80 parts of MN700, 116 parts of AC-009, 2 parts of IPTES, 400 parts of H-50C, 370 parts of H-08C, 1.8 parts of yellow paste, 30 parts of 4A molecular sieve activated powder and 0.2 parts of T12;

[0065] The isocyanate component includes: 165 parts of prep-1, 460 parts of H-50C, 228 parts of H-08C, 138 parts of H-01XP, 5 parts of BYK-W 9010 and 4 parts of blue paste;

[0066] Preparation of polyol component: Add MN700, AC-009, IPTES, H-50C, H-08C, yellow paste, 4A molecular sieve activated powder and T12 into a blender, evacuate the mixture, and stir to disperse uniformly to obtain the polyol component;

[0067] Preparation of isocyanate-terminated prepolymer prep-1: 39 g of MN-3050D was heated to 120°C, evacuated to -0.085 MPa, stirred and dehydrated for 2 h, then cooled to 70°C, broken the vacuum with nitrogen, added 126 g of HMDI, and heated to 80°C. The reaction was kept at this temperature for 3.5 h, then cooled to 60°C while stirring, sealed and stored for later use.

[0068] Preparation of isocyanate component: Add prep-1, H-50C, H-08C, H-01XP, BYK-W9010 and blue paste into a blender, evacuate the mixture, and stir to disperse uniformly to obtain the isocyanate component;

[0069] The obtained polyol component and isocyanate component were placed into a rubber tube with a volume ratio of 1:1 and stored at room temperature.

[0070] Example 3

[0071] The polyol components include: 80 parts of MN700, 116 parts of AC-009, 1 part of IPTMS, 400 parts of H-50C, 370 parts of H-08C, 2.8 parts of yellow paste, 30 parts of 4A molecular sieve activated powder and 0.2 parts of T12;

[0072] The isocyanate component includes: 165 parts of prep-1, 460 parts of H-50C, 228 parts of H-08C, 138 parts of H-01XP, 5 parts of BYK-W 9010 and 4 parts of blue paste;

[0073] Preparation of polyol component: Add MN700, AC-009, IPTMS, H-50C, H-08C, yellow paste, 4A molecular sieve activated powder and T12 into a blender, evacuate the mixture, and stir to disperse evenly to obtain the polyol component;

[0074] Preparation of isocyanate-terminated prepolymer prep-1: 39 g of MN-3050D was heated to 120°C, evacuated to -0.085 MPa, stirred and dehydrated for 2 h, then cooled to 70°C, broken the vacuum with nitrogen, added 126 g of HMDI, and heated to 80°C. The reaction was kept at this temperature for 3.5 h, then cooled to 60°C while stirring, sealed and stored for later use.

[0075] Preparation of isocyanate component: Add prep-1, H-50C, H-08C, H-01XP, BYK-W9010 and blue paste into a blender, evacuate the mixture, and stir to disperse uniformly to obtain the isocyanate component;

[0076] The obtained polyol component and isocyanate component were placed into a rubber tube with a volume ratio of 1:1 and stored at room temperature.

[0077] Comparative Example 1

[0078] The polyol components include: 80 parts of MN700, 116 parts of AC-009, 1 part of KH560, 400 parts of H-50C, 370 parts of H-08C, 2.8 parts of yellow paste, 30 parts of 4A molecular sieve activated powder and 0.2 parts of T12;

[0079] The isocyanate component includes: 165 parts of prep-1, 460 parts of H-50C, 228 parts of H-08C, 138 parts of H-01XP, 5 parts of BYK-W 9010 and 4 parts of blue paste;

[0080] Preparation of polyol component: Add MN700, AC-009, KH560, H-50C, H-08C, yellow paste, 4A molecular sieve activated powder and T12 into a blender, evacuate the mixture, and stir to disperse evenly to obtain the polyol component;

[0081] Preparation of isocyanate-terminated prepolymer prep-1: 39 g of MN-3050D was heated to 120°C, evacuated to -0.085 MPa, stirred and dehydrated for 2 h, then cooled to 70°C, broken the vacuum with nitrogen, added 126 g of HMDI, and heated to 80°C. The reaction was kept at this temperature for 3.5 h, then cooled to 60°C while stirring, sealed and stored for later use.

[0082] Preparation of isocyanate component: Add prep-1, H-50C, H-08C, H-01XP, BYK-W9010 and blue paste into a blender, evacuate the mixture, and stir to disperse uniformly to obtain the isocyanate component;

[0083] The obtained polyol component and isocyanate component were placed into a rubber tube with a volume ratio of 1:1 and stored at room temperature.

[0084] Comparative Example 2

[0085] The polyol components include: 80 parts of MN700, 116 parts of AC-009, 8 parts of IPTES, 393 parts of H-50C, 370 parts of H-08C, 2.8 parts of yellow paste, 30 parts of 4A molecular sieve activated powder and 0.2 parts of T12;

[0086] The isocyanate component includes: 165 parts of prep-1, 460 parts of H-50C, 228 parts of H-08C, 138 parts of H-01XP, 5 parts of BYK-W 9010 and 4 parts of blue paste;

[0087] Preparation of polyol component: Add MN700, AC-009, IPTES, H-50C, H-08C, yellow paste, 4A molecular sieve activated powder and T12 into a blender, evacuate the mixture, and stir to disperse evenly to obtain the polyol component;

[0088] Preparation of isocyanate-terminated prepolymer prep-1: 39 g of MN-3050D was heated to 120°C, evacuated to -0.085 MPa, and stirred for dehydration for 2 h. The mixture was then cooled to 70°C, broken with nitrogen, and 126 g of HMDI was added. The mixture was heated to 80°C and allowed to react for 3.5 h. The mixture was then cooled to 60°C while stirring, sealed, and stored for later use.

[0089] Preparation of isocyanate component: Add prep-1, H-50C, H-08C, H-01XP, BYK-W9010 and blue paste into a blender, evacuate the mixture, and stir to disperse uniformly to obtain the isocyanate component;

[0090] The obtained polyol component and isocyanate component were placed into a rubber tube with a volume ratio of 1:1 and stored at room temperature.

[0091] Table 1 Components and their proportions in Examples and Comparative Examples

[0092] The initial viscosities of the polyol component and the isocyanate component in Example 1, Example 2, Example 3, Comparative Example 1 and Comparative Example 2 were tested, and the aged viscosity of the polyol component was also tested. The test results are shown in Table 2. The polyol component and the isocyanate component in Example 1, Example 2, Example 3, Comparative Example 1 and Comparative Example 2 were mixed in a volume ratio of 1:1 to obtain a two-component polyurethane thermally conductive structural adhesive. The two-component polyurethane thermally conductive structural adhesive was coated between two aluminum substrates to obtain AL-AL splines. The two-component polyurethane thermally conductive structural adhesive was coated between the aluminum substrate and the battery core blue film to obtain AL-blue film splines. After the battery core blue film was plasma treated, the two-component polyurethane thermally conductive structural adhesive was coated between the aluminum substrate and the plasma-treated battery core blue film to obtain AL-plasma-treated blue film splines. Performance tests were performed on the AL-AL, AL-blue film and AL-plasma-treated blue film splines, and the shear strength and T-peel data of the two-component polyurethane thermally conductive structural adhesive were measured. The test results and the standard test method are shown in Table 2.

[0093] Table 2 Test results

[0094] Note: AF refers to the interface damage between the blue film and the adhesive. The damage of the blue film means that the bonding strength between the structural adhesive and the blue film is high.

[0095] The data in Table 2 show that the two-component polyurethane thermal conductive structural adhesive with special isocyanate silane coupling agents (IPES and IPMS) added to the polyol component has improved bonding to the blue film. Without IPES or IPMS, the bonding strength to the blue film is significantly weaker. In this application, the special isocyanate silane coupling agent is added to the polyol component and the polyol condensation reaction generates a siloxane-terminated telechelic resin. When the two components are mixed and cured, the cross-linked structure is embedded. The resulting two-component polyurethane thermal conductive structural adhesive achieves improved bonding performance to the blue film and aluminum substrate. KH560 in Comparative Example 1 is a commonly used silane coupling agent; in Comparative Example 2, the mass ratio of the isocyanate silane coupling agent to the liquid material in the polyol component is 4.08wt%. The viscosity of the polyol component increases significantly with storage time, and the storage stability decreases significantly. The resulting two-component polyurethane thermal conductive structural adhesive has poor bonding to AL-AL and poor shear strength to AL-blue film.

[0096] While the embodiments of the present invention have been described in detail above, it will be apparent to those skilled in the art that various modifications and variations of these embodiments are possible. However, it should be understood that such modifications and variations are within the scope and spirit of the present invention as set forth in the claims. Furthermore, the invention described herein is susceptible to other embodiments and may be practiced or implemented in a variety of ways.

Claims

1. A two-component polyurethane thermally conductive structural adhesive that is easy to bond with a blue film, characterized in that, It includes a polyol component and an isocyanate component, by mass parts; The polyol component includes 70 - 90 parts of polyether polyol, 100 - 200 parts of bio - based oily polyol, 1 - 5 parts of isocyanate - based silane coupling agent, 600 - 800 parts of the first heat - conductive filler, 20 - 36 parts of water absorbent, and 0.16 - 0.24 parts of catalyst; One end of the isocyanate - based silane coupling agent is capped with an isocyanate group, and the other end is capped with a siloxane group. The mass ratio of the isocyanate - based silane coupling agent in the liquid materials of the polyol component is <4 wt%; In the polyol component, the isocyanate - based silane coupling agent condenses with the polyol to form a silicone - capped telechelic resin; The isocyanate component includes 140 - 180 parts of an end - isocyanate - group prepolymer, 750 - 900 parts of the second heat - conductive filler, and 2 - 10 parts of a wetting and dispersing agent.

2. The two-component polyurethane thermally conductive structural adhesive according to claim 1, wherein The isocyanate - based silane coupling agent is one or a combination of two of isocyanatopropyltriethoxysilane and isocyanatopropyltrimethoxysilane.

3. The two-component polyurethane thermally conductive structural adhesive according to claim 1, characterized in that, The molecular weight of the polyether polyol in the polyol component is 400 - 2000.

4. The two-component polyurethane thermally conductive structural adhesive according to claim 1, wherein The bio - based oily polyol is one or more of soybean oil, castor oil, palm oil, hydrogenated castor oil, and modified castor oil.

5. The two-component polyurethane thermally conductive structural adhesive according to claim 1, wherein, The end - isocyanate - group prepolymer is formed by the reaction of a polyether polyol with a molecular weight of 2000 - 4000 and an isocyanate monomer. The NCO content of the end - isocyanate - group prepolymer is 15 - 25%.

6. The two-component polyurethane thermally conductive structural adhesive according to claim 5, wherein The isocyanate monomer is one or two or more of diphenylmethane diisocyanate, dicyclohexylmethane diisocyanate, toluene diisocyanate, isophorone diisocyanate, and hexamethylene diisocyanate.

7. The two-component polyurethane thermally conductive structural adhesive according to claim 6, wherein The mass ratio of the polyether polyol with a molecular weight of 2000 - 4000 to the isocyanate monomer is 1:(3 - 4).

8. The two-component polyurethane heat-conducting structural adhesive according to claim 1, wherein The polyol component and / or the isocyanate component also includes color paste.

9. A method for preparing a two-component polyurethane thermally conductive structural adhesive according to any one of claims 1-8, characterized in that, It includes the following steps: Preparation of the polyol component: Prepare raw materials according to the ratio, add the raw materials required for the polyol component to a blender, evacuate to vacuum, and stir evenly to obtain the polyol component; Preparation of the isocyanate component: First prepare the end - isocyanate - group prepolymer; then take the corresponding mass parts of the end - isocyanate - group prepolymer and mix it with the raw materials required for the isocyanate component, evacuate to vacuum, and stir evenly to obtain the isocyanate component; Mix the prepared polyol component and the isocyanate component in a volume ratio of 1:1 for use.

10. The preparation method according to claim 9, characterized in that, Prepare the end - isocyanate - group prepolymer in the following way: Heat the polyether polyol with a molecular weight of 2000 - 4000 to 115 - 125 °C, stir while evacuating to a negative pressure state to dehydrate, cool down to 65 - 75 °C, fill with nitrogen, add the isocyanate monomer, heat up to 75 - 85 °C, keep warm and react for 3 - 4 h, and cool down to 55 - 65 °C while stirring to obtain the end - isocyanate - group prepolymer.

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