A two-component polyurethane heat-conducting structural adhesive easy to bond blue film and a preparation method thereof

Abstract

The application provides a two-component polyurethane heat-conducting structural adhesive easy to bond blue films and a preparation method, relates to the technical field of two-component polyurethane structural adhesives, and comprises a polyol component and an isocyanate component; the polyol component comprises polyether polyol, bio-based oil polyol, isocyanate-based silane coupling agent, first heat-conducting filler, water absorbent and catalyst; one end of the isocyanate-based silane coupling agent is capped by an isocyanate group, and the other end is capped by a siloxane group; the mass ratio of the isocyanate-based silane coupling agent to liquid materials in the polyol component is < 4 wt%; in the polyol component, the isocyanate-based silane coupling agent and polyol are condensed to generate a siloxane-capped telechelic resin; and the isocyanate component comprises an isocyanate-terminated prepolymer, second heat-conducting filler and wetting dispersant. The application solves the problem that the bonding performance of existing heat-conducting structural adhesives is reduced due to the presence of a large amount of heat-conducting fillers.

Description

Technical Field

[0001] This invention relates to the field of two-component polyurethane structural adhesives, and more particularly to a two-component polyurethane thermally conductive structural adhesive that is easy to bond to blue films and its preparation method. Background Technology

[0002] New energy battery aluminum casings are often covered with an insulating film. During the bonding process, this insulating film frequently detaches, mainly because its outer surface is coated with an anti-stick coating. This insulating film is also known as the cell blue film. For example, Chinese patent CN105751640A describes a cell blue film. 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 new energy PACK assembly lines, the battery cell blue film usually needs to undergo surface treatment to improve the adhesion.

[0003] Two-component polyurethane thermally conductive structural adhesives are commonly used to bond the insulating film and liquid cooling plate of battery cells. However, the high thermal conductivity two-component polyurethane thermally conductive structural adhesives commonly used in the market contain a large amount of thermally conductive filler, which is not conducive to bonding the blue film of the battery cell containing a release coating (anti-stick coating). Therefore, improving the bonding strength of the two-component polyurethane thermally conductive structural adhesive to the blue film of the battery cell is of great significance for improving the overall reliability of the battery.

[0004] Currently, a common method is to change the polarity of the two-component polyurethane thermally conductive structural adhesive by adding low-polarity resin to improve the adhesion strength to the battery cell blue film. Chinese patent CN109593507A describes the use of low-polarity resin to hydrogenate hydroxyl-terminated polybutadiene to improve the adhesion strength of the two-component polyurethane adhesive to the battery cell blue film. Chinese patent CN111534268A selects hydroxyl-terminated polybutadiene or dimer acid modified polyester polyol to improve the adhesion of the two-component polyurethane adhesive to the battery cell blue film.

[0005] Existing technologies use the addition of low-polarity polyols to improve the adhesion of two-component polyurethane thermally conductive structural adhesives to the battery cell blue film. However, the Tg values ​​of low-polarity polyols are very low; for example, the Tg value of hydroxyl-terminated polybutadiene polyol is -70℃. This greatly affects the Tg value of the two-component polyurethane thermally conductive structural adhesive, which in turn leads to a decrease in the adhesion performance of the two-component polyurethane thermally conductive structural adhesive to hard materials such as metals. This reduces the universality of the two-component polyurethane thermally conductive structural adhesive in the bonding application of battery cell blue film and aluminum liquid cooling plate, resulting in a trade-off.

[0006] In addition, hydroxyl-terminated polybutadiene or dimer acid modified polyester polyols have not been widely adopted in China. Currently, the two types of polyols on the market are POLY BD (now sold to Pacific Avenue Capital) under Total and Priplast series products of Cargill. The current market price of these two products ranges from 60 to 120 yuan / kg, which is much higher than the price of 10 to 50 yuan / kg of traditional polyurethane polyol resins. The high price of low polar polyols limits the widespread use of two-component polyurethane thermally conductive structural adhesives containing low polar polyols.

[0007] Therefore, there is an urgent need to develop a two-component polyurethane thermally conductive structural adhesive that is easy to bond with blue film and its preparation method to solve the above problems. Summary of the Invention

[0008] The purpose of this invention is to provide a two-component polyurethane thermally conductive structural adhesive that is easy to bond with blue films and its preparation method, which solves the problem of effectively improving the bonding performance of existing thermally conductive structural adhesives to insulating films, aluminum substrates, etc. at a lower cost.

[0009] To achieve the above objectives, in a first aspect, the present invention provides a two-component polyurethane thermally conductive structural adhesive that is easy to bond with blue films, the two-component polyurethane thermally conductive structural adhesive comprising a polyol component and an isocyanate component, in parts by mass.

[0010] The polyol component comprises 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 first thermally 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, and the isocyanate-based silane coupling agent accounts for <4 wt% of the liquid component in the polyol component; in the polyol component, the isocyanate-based silane coupling agent reacts with the polyol in a condensation reaction to generate a siloxane-capped telechelic resin;

[0011] The isocyanate component comprises 140-180 parts of terminal isocyanate group prepolymer, 750-900 parts of second thermally conductive filler, and 2-10 parts of wetting and dispersing agent.

[0012] Optionally, the isocyanate-based silane coupling agent is one or a combination of two of propyltriethoxysilane and propyltrimethoxysilane.

[0013] Optionally, the polyether polyol in the polyol component has a molecular weight of 400-2000.

[0014] Optionally, the bio-based oily polyol is one or more of soybean oil, castor oil, palm oil, hydrogenated castor oil, and modified castor oil.

[0015] Optionally, the terminal isocyanate prepolymer is generated by reacting a polyether polyol with a molecular weight of 2000-4000 with an isocyanate monomer, and the NCO content of the terminal isocyanate prepolymer is 15-25%.

[0016] Optionally, the isocyanate monomer is one or more of diphenylmethane diisocyanate, dicyclohexylmethane diisocyanate, toluene diisocyanate, isophorone diisocyanate, and hexamethylene isocyanate.

[0017] Optionally, the mass ratio of the polyether polyol with a molecular weight of 2000-4000 to the isocyanate monomer is 1:(3-4).

[0018] Optionally, the polyol component and / or the isocyanate component may further include a color paste.

[0019] Secondly, the present invention provides a method for preparing a two-component polyurethane thermally conductive structural adhesive, comprising the following steps:

[0020] Preparation of polyol components: Prepare raw materials according to the formula, add the raw materials required for polyol components to a mixer, vacuum, and stir evenly to obtain the polyol components;

[0021] Preparation of isocyanate component: First, prepare terminal isocyanate group prepolymer; then take the corresponding mass parts of the terminal isocyanate group prepolymer and mix it with the raw materials required for isocyanate component, vacuum, and stir evenly to obtain the isocyanate component.

[0022] The obtained polyol component and the isocyanate component are mixed at a volume ratio of 1:1 for use.

[0023] Optionally, the terminal isocyanate prepolymer is prepared as follows: a polyether polyol with a molecular weight of 2000-4000 is heated to 115-125°C, stirred while being evacuated to a negative pressure state, dehydrated, cooled to 65-75°C, purged with nitrogen, added isocyanate monomer, heated to 75-85°C, and reacted at this temperature for 3-4 hours, while being stirred and cooled to 55-65°C to obtain the terminal isocyanate prepolymer.

[0024] The beneficial effects of this invention include:

[0025] 1. The two-component polyurethane thermally conductive structural adhesive of this application changes the polarity of the polyurethane resin generated with polyol by adding isocyanate-based silane coupling agent, which effectively improves the adhesion to the blue film of the battery cell, and the formula does not contain high-cost low-grade resin, thus keeping the cost at a low level.

[0026] 2. Because a small amount of isocyanate-based silane coupling agent is added to the two-component polyurethane thermally conductive structural adhesive of this application, the storage stability of the polyol component can be maintained and the Tg value of the two-component polyurethane thermally conductive structural adhesive will not be changed.

[0027] 3. The two-component polyurethane thermally conductive structural adhesive of this application can achieve ideal (industry standard) bonding strength for bonding the blue film of the battery cell without plasma treatment.

[0028] 4. The two-component polyurethane thermally conductive structural adhesive of this application improves the adhesion to the blue film of the battery cell while maintaining the adhesion strength to the aluminum substrate, and has a wide range of applications. Attached Figure Description

[0029] Figure 1 This is a schematic diagram of the structure of the blue film in a battery cell in the prior art;

[0030] Figure 2 This is a schematic flowchart of the preparation method of the two-component polyurethane thermally conductive structural adhesive of the present invention. Detailed Implementation

[0031] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0032] This invention improves the adhesion of two-component polyurethane thermally conductive structural adhesive to insulating films by adding isocyanate-based silane coupling agents, and can even achieve good adhesion without plasma treatment of the insulating film.

[0033] This invention provides a two-component polyurethane thermally conductive structural adhesive that is easy to bond with blue film. The two-component polyurethane thermally conductive structural adhesive includes a polyol component and an isocyanate component, in parts by weight.

[0034] The polyol component comprises 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 first thermally 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, and the isocyanate-based silane coupling agent accounts for <4 wt% of the liquid component in the polyol component; in the polyol component, the isocyanate-based silane coupling agent reacts with the polyol in a condensation reaction to generate a siloxane-capped telechelic resin;

[0035] The isocyanate component comprises 140-180 parts of terminal isocyanate group prepolymer, 750-900 parts of second thermally conductive filler, and 2-10 parts of wetting and dispersing agent.

[0036] In some embodiments of the present invention, a portion of the hydroxyl groups at the end of the polyol are capped using the isocyanate-based silane coupling agent to generate a siloxane-capped telechelic resin. The specific generation route is as follows:

[0037]

[0038] In some embodiments of the present invention, the liquid component of the polyol component is composed of polyether polyol and bio-based oily polyol.

[0039] 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-size thermally conductive filler and 290-450 parts of small-particle-size thermally conductive filler, wherein the particle size range of the large-particle-size thermally conductive filler is 40-60 micrometers and the particle size range of the small-particle-size thermally conductive filler is 6-10 micrometers.

[0040] In some embodiments of the present invention, the second thermally conductive filler is composed of the following raw materials in parts by weight: 365-555 parts of large-particle-size thermally conductive filler, 180-275 parts of small-particle-size thermally conductive filler, and 110-166 parts of ultrafine powder thermally conductive filler. The particle size range of the large-particle-size thermally conductive filler is 40-60 micrometers, the particle size range of the small-particle-size thermally conductive filler is 6-10 micrometers, and the particle size range of the ultrafine powder thermally conductive filler is 0.8-1.2 micrometers.

[0041] In some embodiments of the present invention, the isocyanate-based silane coupling agent is one or a combination of two of propyltriethoxysilane and propyltrimethoxysilane.

[0042] In some embodiments of the present invention, the polyether polyol in the polyol component has a molecular weight of 400-2000.

[0043] 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.

[0044] In some specific embodiments of the present invention, the terminal isocyanate-based prepolymer is generated by reacting a polyether polyol with a molecular weight of 2000-4000 with an isocyanate monomer, and the NCO content of the terminal isocyanate-based prepolymer is 15-25%. Specifically, the NCO content of the terminal isocyanate-based prepolymer is calculated as: (mass of isocyanate groups in the terminal isocyanate-based prepolymer) ÷ (mass of the terminal isocyanate-based prepolymer) × 100%.

[0045] 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 abbreviation for diphenylmethane diisocyanate is MDI, the abbreviation for dicyclohexylmethane diisocyanate is HMDI, the abbreviation for toluene diisocyanate is TDI, the abbreviation for isophorone diisocyanate is IPDI, and the abbreviation for hexamethylene isocyanate is HDI.

[0046] 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).

[0047] In some embodiments of the present invention, the polyol component and / or the isocyanate component further include a color paste.

[0048] This invention provides a method for preparing a two-component polyurethane thermally conductive structural adhesive, referring to... Figure 2 This includes the following steps:

[0049] S1: Preparation of polyol components: Prepare raw materials according to the formula, add the required raw materials for polyol components to a mixer, vacuum, and stir evenly to obtain the polyol components;

[0050] S2: Preparation of isocyanate component: First, prepare terminal isocyanate group prepolymer; then take the corresponding mass fraction of the terminal isocyanate group prepolymer and mix it with the raw materials required for isocyanate component, vacuum, and stir evenly to obtain the isocyanate component.

[0051] S3: The obtained polyol component and the isocyanate component are mixed at a volume ratio of 1:1 and used.

[0052] In some embodiments of the present invention, the terminal isocyanate prepolymer is prepared as follows: a polyether polyol with a molecular weight of 2000-4000 is heated to 115-125°C, stirred while being evacuated to a negative pressure state, dehydrated, cooled to 65-75°C, purged with nitrogen, added isocyanate monomer, heated to 75-85°C, and reacted at this temperature for 3-4 hours, while being stirred and cooled to 55-65°C to obtain the terminal isocyanate prepolymer.

[0053] In Examples 1-3 and the comparative examples of this invention, the raw materials involved include: polyether polyols sourced from Shandong Lanxing Dongda Co., Ltd., with two brands: MN700 (molecular weight 700) and MN-3050D (molecular weight 3000); modified castor oil sourced from Ito Corporation of Japan, with the brand name AC-009; and γ-glycidyl etheroxypropyltrimethoxysilane sourced from Shanghai Hongshun Biotechnology Co., Ltd., with the brand name KH560, which is a common epoxy silane coupling agent. The isocyanate-based silane coupling agents are: 3-isocyanate propyltriethoxysilane sourced from Momentive Corporation, with the brand name Silquest A-1310 (abbreviated as IPTES); and 3-isocyanate propyltrimethoxysilane sourced from Momentive Corporation, with the brand name Silquest. Y-5187, abbreviated as IPTMS; the catalyst is dibutyltin dilaurate (abbreviated as T12), sourced from Shandong Maofa Chemical; the thermally conductive filler can be aluminum hydroxide, with large-particle-size thermally conductive filler being Shanghai Jiaqi Chemical's H-50C (D50 is 50 microns) aluminum hydroxide, small-particle-size thermally conductive filler being Shanghai Jiaqi Chemical's H-08C (D50 is 8 microns) aluminum hydroxide, and ultrafine powder thermally conductive filler being Shanghai Jiaqi Chemical's H-01XP (D50 is 1 micron) aluminum hydroxide; the wetting and dispersing agent is BYK-W 9010, the water absorbent is 4A molecular sieve activated powder, and the yellow and blue slurries are selected from commercially available conventional types.

[0054] Example 1

[0055] 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.

[0056] The isocyanate components include: 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;

[0057] Preparation of polyol components: MN700, AC-009, IPTES, H-50C, H-08C, yellow paste, 4A molecular sieve activation powder and T12 are added to a mixer, vacuumed and stirred to disperse evenly to obtain polyol components.

[0058] 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, the vacuum was broken with nitrogen, 126 g of HMDI was added, and the temperature was raised to 80 °C. The reaction was maintained at this temperature for 3.5 h, and the temperature was lowered to 60 °C while stirring. The mixture was then sealed and stored for later use.

[0059] Preparation of isocyanate component: prep-1, H-50C, H-08C, H-01XP, BYK-W9010 and blue paste were added to a mixer, vacuumed and stirred to disperse evenly to obtain isocyanate component;

[0060] The obtained polyol component and isocyanate component were packed into a 1:1 volume ratio tube and stored at room temperature.

[0061] Example 2

[0062] 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 activation powder, and 0.2 parts of T12.

[0063] The isocyanate components include: 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;

[0064] Preparation of polyol components: MN700, AC-009, IPTES, H-50C, H-08C, yellow paste, 4A molecular sieve activation powder and T12 are added to a mixer, vacuumed and stirred to disperse evenly to obtain polyol components.

[0065] 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, the vacuum was broken with nitrogen, 126 g of HMDI was added, and the temperature was raised to 80 °C. The reaction was maintained at this temperature for 3.5 h, and the temperature was lowered to 60 °C while stirring. The mixture was then sealed and stored for later use.

[0066] Preparation of isocyanate component: prep-1, H-50C, H-08C, H-01XP, BYK-W9010 and blue paste were added to a mixer, vacuumed and stirred to disperse evenly to obtain isocyanate component;

[0067] The obtained polyol component and isocyanate component were packed into a 1:1 volume ratio tube and stored at room temperature.

[0068] Example 3

[0069] 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.

[0070] The isocyanate components include: 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;

[0071] Preparation of polyol components: MN700, AC-009, IPTMS, H-50C, H-08C, yellow paste, 4A molecular sieve activation powder and T12 are added to a mixer, vacuumed and stirred to disperse evenly to obtain polyol components.

[0072] 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, the vacuum was broken with nitrogen, 126 g of HMDI was added, and the temperature was raised to 80 °C. The reaction was maintained at this temperature for 3.5 h, and the temperature was lowered to 60 °C while stirring. The mixture was then sealed and stored for later use.

[0073] Preparation of isocyanate component: prep-1, H-50C, H-08C, H-01XP, BYK-W9010 and blue paste were added to a mixer, vacuumed and stirred to disperse evenly to obtain isocyanate component;

[0074] The obtained polyol component and isocyanate component were packed into a 1:1 volume ratio tube and stored at room temperature.

[0075] Comparative Example 1

[0076] 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.

[0077] The isocyanate components include: 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;

[0078] Preparation of polyol components: MN700, AC-009, KH560, H-50C, H-08C, yellow paste, 4A molecular sieve activation powder and T12 are added to a mixer, vacuumed and stirred to disperse evenly to obtain polyol components.

[0079] 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, the vacuum was broken with nitrogen, 126 g of HMDI was added, and the temperature was raised to 80 °C. The reaction was maintained at this temperature for 3.5 h, and the temperature was lowered to 60 °C while stirring. The mixture was then sealed and stored for later use.

[0080] Preparation of isocyanate component: prep-1, H-50C, H-08C, H-01XP, BYK-W9010 and blue paste were added to a mixer, vacuumed and stirred to disperse evenly to obtain isocyanate component;

[0081] The obtained polyol component and isocyanate component were packed into a 1:1 volume ratio tube and stored at room temperature.

[0082] Comparative Example 2

[0083] 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.

[0084] The isocyanate components include: 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;

[0085] Preparation of polyol components: MN700, AC-009, IPTES, H-50C, H-08C, yellow paste, 4A molecular sieve activation powder and T12 are added to a mixer, vacuumed and stirred to disperse evenly to obtain polyol components.

[0086] 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, the vacuum was broken with nitrogen, 126 g of HMDI was added, and the temperature was raised to 80 °C. The reaction was maintained at this temperature for 3.5 h, and the temperature was lowered to 60 °C while stirring. The mixture was then sealed and stored for later use.

[0087] Preparation of isocyanate component: prep-1, H-50C, H-08C, H-01XP, BYK-W9010 and blue paste were added to a mixer, vacuumed and stirred to disperse evenly to obtain isocyanate component;

[0088] The obtained polyol component and isocyanate component were packed into a 1:1 volume ratio tube and stored at room temperature.

[0089] Table 1. Components and their proportions in the examples and comparative examples.

[0090]

[0091] The initial viscosities of the polyol and isocyanate components in Examples 1, 2, 3, Comparative Example 1, and Comparative Example 2 were tested, and the aging viscosity of the polyol component was also tested. The test results are shown in Table 2. A two-component polyurethane thermally conductive structural adhesive was obtained by mixing the polyol and isocyanate components in Examples 1, 2, 3, Comparative Example 1, and Comparative Example 2 at a volume ratio of 1:1. The two-component polyurethane thermally conductive structural adhesive was coated between two aluminum substrates to obtain AL-AL samples. The two-component polyurethane thermally conductive structural adhesive was coated between an aluminum substrate and a blue film of a battery cell to obtain AL-blue film samples. After plasma treatment of the blue film of the battery cell, the two-component polyurethane thermally conductive structural adhesive was coated between an aluminum substrate and a plasma-treated blue film of the battery cell to obtain AL-plasma-treated blue film samples. Performance tests were conducted on the AL-AL, AL-blue film, and AL-plasma-treated blue film samples. The shear strength and T-peel data of the two-component polyurethane thermally conductive structural adhesive were measured. The test results and the test standard methods are shown in Table 2.

[0092] Table 2 Test Results

[0093]

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

[0095] As shown in Table 2, the two-component polyurethane thermally conductive structural adhesive with the addition of special isocyanate-based silane coupling agents (IPES, IPMS) to the polyol component improves the adhesion of the blue film. Without IPES or IPMS, the adhesion strength of the blue film is significantly weaker. In this application, the special isocyanate-based silane coupling agent is added to the polyol component and reacts with the polyol to generate a siloxane-terminated telechelic resin. This resin is embedded in the cross-linked structure during the curing of the two components, resulting in a two-component polyurethane thermally conductive structural adhesive that improves the adhesion performance of the blue film and the aluminum substrate. KH560 in Comparative Example 1 is a commonly used silane coupling agent. In Comparative Example 2, the isocyanate-based silane coupling agent accounts for 4.08 wt% of the liquid component in the polyol component. The viscosity of the polyol component increases significantly with storage time, and the storage stability decreases significantly. The resulting two-component polyurethane thermally conductive structural adhesive shows poorer adhesion to AL-AL, and the shear strength of the AL-blue film also deteriorates.

[0096] While 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 can be made to these embodiments. However, it should be understood that such modifications and variations fall within the scope and spirit of the invention as set forth in the claims. Furthermore, the invention described herein may have other embodiments and can be implemented or carried out in various ways.

Claims

1. A two-component polyurethane thermally conductive structural adhesive that easily bonds blue films, characterized in that, Includes polyol components and isocyanate components, by mass parts; The polyol component comprises 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 first thermally 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, and the isocyanate-based silane coupling agent accounts for <4 wt% of the liquid component in the polyol component; In the polyol component, the isocyanate-based silane coupling agent reacts with the polyol in a condensation reaction to generate a siloxane-terminated telechelic resin. The isocyanate component comprises 140-180 parts of terminal isocyanate group prepolymer, 750-900 parts of second thermally conductive filler, and 2-10 parts of wetting and dispersing agent.

2. The two-component polyurethane thermally conductive structural adhesive according to claim 1, characterized in that, The isocyanate-based silane coupling agent is one or a combination of two of propyltriethoxysilane and propyltrimethoxysilane.

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

4. The two-component polyurethane thermally conductive structural adhesive according to claim 1, characterized in that, 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, characterized in that, The terminal isocyanate prepolymer is generated by reacting a polyether polyol with a molecular weight of 2000-4000 with an isocyanate monomer, and the NCO content of the terminal isocyanate prepolymer is 15-25%.

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

7. The two-component polyurethane thermally conductive structural adhesive according to claim 6, characterized in that, 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 thermally conductive structural adhesive according to claim 1, characterized in that, The polyol component and / or the isocyanate component also include color paste.

9. A method for preparing a two-component polyurethane thermally conductive structural adhesive as described in any one of claims 1-8, characterized in that, Includes the following steps: Preparation of polyol components: Prepare raw materials according to the formula, add the raw materials required for polyol components to a mixer, vacuum, and stir evenly to obtain the polyol components; Preparation of isocyanate component: First, prepare terminal isocyanate group prepolymer; then take the corresponding mass parts of the terminal isocyanate group prepolymer and mix it with the raw materials required for isocyanate component, vacuum, and stir evenly to obtain the isocyanate component. The obtained polyol component and the isocyanate component are mixed at a volume ratio of 1:1 for use.

10. The preparation method according to claim 9, characterized in that, The terminal isocyanate prepolymer is prepared as follows: a polyether polyol with a molecular weight of 2000-4000 is heated to 115-125°C, stirred while being evacuated to a negative pressure state, dehydrated, cooled to 65-75°C, purged with nitrogen, added isocyanate monomer, heated to 75-85°C, and reacted at this temperature for 3-4 hours. While stirring, the temperature is then lowered to 55-65°C to obtain the terminal isocyanate prepolymer.

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