Moisture-resistant and heat-resistant epoxy heat-conducting structural adhesive, and preparation method and application thereof

Abstract

The application provides a moisture and heat aging resistant epoxy heat conductive structural adhesive, which comprises the following raw material components by weight: component A: composite epoxy resin 18-25 parts, diluent 2-5 parts, and composite heat conductive filler 120-180 parts; component B: curing agent 15-20 parts, accelerator 5-12 parts, and composite heat conductive filler 156-225 parts; wherein the composite epoxy resin is obtained by blending and reacting raw materials including bisphenol A type epoxy resin, phenolic epoxy resin, naphthalene type epoxy resin and toughening agent; the application also provides a preparation method of the moisture and heat aging resistant epoxy heat conductive structural adhesive and application of the moisture and heat aging resistant epoxy heat conductive structural adhesive in the fields of electronic devices, new energy automobile batteries, energy storage and the like; the moisture and heat aging resistant epoxy heat conductive structural adhesive has excellent heat conductive performance, bonding performance, electrical insulation performance and moisture and heat stability.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of heat-conducting glue, in particular to a moisture and heat aging resistant epoxy heat-conducting structural glue and a preparation method and application thereof. BACKGROUND

[0002] With the rapid development of the electronic industry, especially in the fields of new energy vehicles, electronic equipment, energy storage, etc., the heat dissipation requirements for electronic components are becoming higher and higher, and the requirements for thermal interface materials are also becoming higher and higher. Among them, for the heat-conducting bonding application of automobile power batteries, the heat-conducting adhesive is required to have excellent interface heat conduction and insulation properties, and excellent bonding performance to plastic materials such as PET, PI and PC and metal materials such as aluminum alloy without surface treatment when cured at room temperature, and in addition, it is particularly required to have moisture and heat resistance in terms of safety and reliability. However, the insulation and bonding performance of the traditional epoxy heat-conducting glue will decrease significantly after long-term use in a high-humidity and high-temperature environment, which affects the stability and service life of electronic components. This is because in a humid and hot environment, especially the moisture-absorbing PET material, and the glue layer is prone to interface delamination, resulting in a sharp decline in overall performance, which has become an important constraint factor for the application of heat-conducting structural glue in the fields of new energy vehicles, electronic equipment, energy storage, etc.

[0003] Therefore, it is urgent to develop a moisture and heat aging resistant epoxy heat-conducting structural glue. SUMMARY

[0004] In view of the above-mentioned shortcomings of the prior art, the purpose of the present application is to provide a moisture and heat aging resistant epoxy heat-conducting structural glue and a preparation method and application thereof, so as to solve the problem that the insulation and bonding performance of the epoxy heat-conducting glue in the prior art will decrease significantly after long-term use in a high-humidity and high-temperature environment.

[0005] To achieve the above-mentioned purposes and other related purposes, the present application provides a moisture and heat aging resistant epoxy heat-conducting structural glue, which comprises the following raw material components by weight:

[0006] Component A: 18-25 parts of composite epoxy resin, 2-5 parts of diluent, 120-180 parts of composite heat-conducting filler;

[0007] Component B: 15-20 parts of curing agent, 5-12 parts of accelerator, 156-225 parts of composite heat-conducting filler;

[0008] The composite epoxy resin is obtained by blending and reacting raw materials including bisphenol A type epoxy resin, phenolic epoxy resin, naphthalene type epoxy resin and toughening agent.

[0009] The present application also provides a preparation method of the moisture and heat aging resistant epoxy heat-conducting structural glue as described above, comprising the following steps:

[0010] (1) The composite epoxy resin, diluent, and composite heat-conductive filler are dispersed and mixed in a homogenizer, and after vacuum defoaming treatment, a slurry of component A is obtained;

[0011] (2) The curing agent, accelerator, and composite heat-conductive filler are mixed uniformly in a homogenizer under vacuum conditions, and a slurry of component B is obtained;

[0012] (3) The slurry of component A and the slurry of component B are mixed in equal volume ratio, and a moisture and heat aging resistant epoxy heat-conductive structural adhesive is obtained.

[0013] The application also provides an application of the moisture and heat aging resistant epoxy heat-conductive structural adhesive in the new energy automobile, electronic equipment, and energy storage field.

[0014] As described above, the moisture and heat aging resistant epoxy heat-conductive structural adhesive and the preparation method and application thereof have the following beneficial effects:

[0015] The moisture and heat aging resistant epoxy heat-conductive structural adhesive of the application is subjected to modification treatment, and a group with heat resistance and moisture resistance is introduced into the epoxy resin structure. The alkoxyl, amino, and hydroxyl, naphthyl, and other functional groups are reacted with the epoxy group in the epoxy resin to generate a grafted or block copolymer, so as to improve the heat distortion temperature and moisture and heat resistance of the epoxy resin. Then, the second phase enhancement of the composite heat-conductive filler is utilized to improve the heat-conductive performance and bonding performance of the composite material. Meanwhile, the addition of the composite heat-conductive filler can also enhance the material particles and hinder the continuous expansion of the microcracks that have germinated. Further, through the modification and particle grading of the composite heat-conductive filler, the maximum filling amount of the high-viscosity system is improved, the barrier property to water molecules is enhanced, the absorption of the hydroxyl group in the resin to water molecules is reduced, and the volume expansion of the composite heat-conductive filler due to water or air oxidation can fill the gap of the microcracks, block the water diffusion channel of the microcracks, slow down the diffusion of water, and thus reduce the influence of moisture and heat aging on the comprehensive performance of the material.

[0016] The moisture and heat aging resistant epoxy heat-conductive structural adhesive of the application has excellent heat-conductive performance, bonding performance, electrical insulation performance, and moisture and heat resistance, and can be widely applied in the electronic device, new energy automobile battery, energy storage, and other fields to provide excellent heat-conductive and bonding solutions. DETAILED DESCRIPTION

[0017] The embodiments of the application are described below through specific examples, and those skilled in the art can easily understand other advantages and effects of the application from the disclosure. The application can also be implemented or applied through different specific embodiments, and the details in the specification can be modified or changed based on different viewpoints and applications without departing from the spirit of the application.

[0018] It should be noted that when a numerical range is disclosed herein, the range is considered continuous and includes the minimum and maximum values ​​of the range, as well as every value between the minimum and maximum values. Furthermore, when the range refers to an integer, it includes every integer between the minimum and maximum values ​​of the range. Additionally, when multiple ranges are provided to describe a feature or characteristic, the ranges may be combined. In other words, unless otherwise specified, all ranges disclosed herein should be understood to include any and all subranges contained therein. For example, the specified range from "1 to 10" should be considered to include any and all subranges between the minimum value 1 and the maximum value 10. Exemplary subranges of the range 1 to 10 include, but are not limited to, 1 to 6.1, 3.5 to 7.8, 5.5 to 10, etc.

[0019] Furthermore, it should be understood that the one or more method steps mentioned in this invention do not preclude the existence of other method steps before or after the combined steps, or the insertion of other method steps between these explicitly mentioned steps, unless otherwise stated; moreover, unless otherwise stated, the numbering of each method step is merely a convenient tool for identifying each method step, and not for limiting the order of the method steps or limiting the scope of the invention. Changes or adjustments to their relative relationships, without substantially altering the technical content, should also be considered as within the scope of the invention.

[0020] The first aspect of this invention provides an epoxy thermally conductive structural adhesive resistant to damp heat aging, comprising the following raw material components in parts by weight:

[0021] Component A: 18-25 parts of composite epoxy resin, 2-5 parts of diluent, and 120-180 parts of composite thermally conductive filler;

[0022] Component B: 15-20 parts curing agent, 5-12 parts accelerator, and 156-225 parts composite thermally conductive filler.

[0023] The composite epoxy resin in component A can be 18-20 parts, 20-22 parts, 22-24 parts, or 24-25 parts; the composite epoxy resin serves as the matrix resin, providing basic adhesive and mechanical properties.

[0024] The diluent in component A can be 2-3 parts, 3-4 parts, or 4-5 parts;

[0025] The composite thermally conductive filler in component A can be 120-130 parts, 130-140 parts, 140-150 parts, 150-160 parts, 160-170 parts, or 170-180 parts;

[0026] The curing agent in component B can be 15-16 parts, 16-17 parts, 17-18 parts, 18-19 parts, or 19-20 parts;

[0027] The accelerator in the B component can be 5-7 parts, 7-9 parts, 9-11 parts, or 11-12 parts;

[0028] The composite heat-conducting filler in the B component can be 156-160 parts, 160-170 parts, 170-180 parts, 180-190 parts, 190-200 parts, 200-210 parts, 210-220 parts, or 220-225 parts.

[0029] The weight ratio of the bisphenol A type epoxy resin, the phenolic epoxy resin, the naphthalene type epoxy resin, and the toughening agent is 60-72:10-20:10-20:5-8. For example, the weight ratio is 60-62:10-20:10-20:5-8, 62-64:10-20:10-20:5-8, 64-66:10-20:10-20:5-8, 66-68:10-20:10-20:5-8, 68-70:10-20:10-20:5-8, 70-72:10-20:10-20:5-8, 60-72:10-12:10-20:5-8, 60-72:12-14:10-20:5-8, 60-72:14-16:10-20:5-8, 60-72:16-18:10-20:5-8, 60-72:18-20:10-20:5-8, 60-72:10-20:10-12:5-8, 60-72:10-20:12-14:5-8, 60-72:10-20:14-16:5-8, 60-72:10-20:16-18:5-8, 60-72:10-20:18-20:5-8, 60-72:10-20:10-20:5-6, 60-72:10-20:10-20:6-7, or 60-72:10-20:10-20:7-8.

[0030] The phenolic epoxy resin is phenolic epoxy resin F51.

[0031] The naphthalene type epoxy resin is naphthalene type epoxy resin EBA-65.

[0032] The toughening agent is a thermoplastic resin, specifically polyurethane.

[0033] In the moisture and heat aging resistant epoxy heat-conducting structural adhesive, the composite heat-conducting filler is obtained by mixing raw materials including modified aluminum oxide with different particle sizes and modified aluminum nitride with different particle sizes. The composite heat-conducting filler improves the heat-conducting performance of the adhesive. The particle size is the median particle size.

[0034] The modified alumina has a median particle size of 1-100 μm. For example, 1-10 μm, 10-20 μm, 20-30 μm, 30-40 μm, 40-50 μm, 50-60 μm, 60-70 μm, 70-80 μm, 80-90 μm, or 90-100 μm. In a preferred embodiment of the application, the modified alumina has a median particle size of 1 μm, 40 μm, or 90 μm.

[0035] The modified alumina is alumina coated with a coupling agent. The coupling agent is γ-glycidoxypropyltrimethoxysilane.

[0036] The modified aluminum nitride has a median particle size of 1-70 μm. For example, 1-5 μm, 5-10 μm, 10-15 μm, 15-20 μm, 20-30 μm, 30-40 μm, 40-50 μm, 50-60 μm, or 60-70 μm. In a preferred embodiment of the application, the modified aluminum nitride has a median particle size of 5 μm, 15 μm, or 60 μm.

[0037] The modified aluminum nitride is aluminum nitride modified with a coupling agent. The coupling agent is γ-glycidoxypropyltrimethoxysilane.

[0038] The coupling agent is pre-coated on the surface of the thermally conductive powder. The coupling agent improves the compatibility between the composite thermally conductive filler and the composite epoxy resin matrix by grafting hydrophobic groups on the surface of the thermally conductive powder. The coupling agent enhances the adhesive strength of the glue and further reduces the impact of the hydrolysis of the composite thermally conductive filler during the humid heat aging process.

[0039] The weight ratio of the modified alumina to the modified aluminum nitride is 57-77:27-39. For example, 57-59:27-39, 59-61:27-39, 61-63:27-39, 63-65:27-39, 65-67:27-39, 67-69:27-39, 69-71:27-39, 71-73:27-39, 73-75:27-39, 75-77:27-39, 57-77:27-29, 57-77:29-31, 57-77:31-33, 57-77:33-35, 57-77:35-37, or 57-77:37-39. In a preferred embodiment of the present application, the ratio of the modified alumina with a median particle size of 1 μm, 40 μm, and 90 μm is 5-10:15-20:37-47. For example, 5-6:15-20:37-47, 6-7:15-20:37-47, 7-8:15-20:37-47, 8-9:15-20:37-47, 9-10:15-20:37-47, 5-10:15-16:37-47, 5-10:16-17:37-47, 5-10:17-18:37-47, 5-10:18-19:37-47, 5-10:19-20:37-47, 5-10:15-20:37-39, 5-10:15-20:39-41, 5-10:15-20:41-43, 5-10:15-20:43-45, or 5-10:15-20:45-47. In a preferred embodiment of the present application, the ratio of the modified aluminum nitride with a median particle size of 5 μm, 15 μm, and 60 μm is 2-4:9-15:16-20. For example, 2-3:9-15:16-20, 3-4:9-15:16-20, 2-4:9-10:16-20, 2-4:10-11:16-20, 2-4:11-12:16-20, 2-4:12-13:16-20, 2-4:13-14:16-20, 2-4:14-15:16-20, 2-4:9-15:16-17, 2-4:9-15:17-18, 2-4:9-15:18-19, or 2-4:9-15:19-20.

[0040] In the moisture and heat aging resistant epoxy heat conductive structural adhesive of the present application, the diluent is polypropylene glycol diglycidyl ether. The diluent can reduce the standard numerical viscosity, and improve the toughness, extensibility, and impact resistance of the system.

[0041] In the moisture and heat aging resistant epoxy heat conductive structural adhesive of the present application, the toughening agent is a thermoplastic resin, specifically a polyurethane resin. The toughening agent can improve the flexibility and impact resistance of the adhesive.

[0042] The moisture and heat aging resistant epoxy heat conductive structural adhesive provided by the application is prepared by using the polythiol QE-340M as the curing agent.

[0043] The moisture and heat aging resistant epoxy heat conductive structural adhesive provided by the application is prepared by using the polythiol QE-340M as the curing agent.

[0044] The moisture and heat aging resistant epoxy heat conductive structural adhesive provided by the application is prepared by using the polythiol QE-340M as the curing agent.

[0045] (1) dispersing and mixing the composite epoxy resin, the diluent and the composite heat conductive filler in a homogenizer, and then performing vacuum defoaming treatment to obtain the slurry of the component A;

[0046] (2) uniformly mixing the curing agent, the accelerator and the composite heat conductive filler in the homogenizer under vacuum to obtain the slurry of the component B;

[0047] (3) mixing the slurry of the component A and the slurry of the component B in equal volume ratio to obtain the moisture and heat aging resistant epoxy heat conductive structural adhesive.

[0048] In the preparation method, the rotating speed of the homogenizer in step (1) is 800-1500 r / min. For example, the rotating speed is 800-900 r / min, 900-1000 r / min, 1000-1100 r / min, 1100-1200 r / min, 1200-1300 r / min, 1300-1400 r / min or 1400-1500 r / min. In the preparation method, the time for dispersing and mixing in step (1) is 10-30 min. For example, the time is 10-15 min, 15-20 min, 20-25 min or 25-30 min.

[0049] In the preparation method, the pressure of the vacuum in step (1) is-0.090 to-0.095 Mpa. For example, the pressure is-0.090 to-0.091 Mpa, -0.091 to-0.092 Mpa, -0.092 to-0.093 Mpa, -0.093 to-0.094 Mpa or-0.094 to-0.095 Mpa.

[0050] In the preparation method, the rotating speed of the homogenizer in step (2) is 800-1500 r / min. For example, the rotating speed is 800-900 r / min, 900-1000 r / min, 1000-1100 r / min, 1100-1200 r / min, 1200-1300 r / min, 1300-1400 r / min or 1400-1500 r / min.

[0051] In the preparation method, the mixing time in step (2) is 10-30 min. For example, 10-15 min, 15-20 min, 20-25 min or 25-30 min.

[0052] In the preparation method, the pressure of the vacuum in step (2) is -0.090 to -0.095 Mpa. For example, -0.090 to -0.091 Mpa, -0.091 to -0.092 Mpa, -0.092 to -0.093 Mpa, -0.093 to -0.094 Mpa or -0.094 to -0.095 Mpa.

[0053] In the preparation method, the composite epoxy resin in step (1) is obtained by mixing raw materials including bisphenol A type epoxy resin, phenolic epoxy resin and naphthalene type epoxy resin, heating and stirring, and then vacuum defoaming treatment.

[0054] The temperature of the heating and stirring is 40-60℃. For example, 40-45℃, 45-50℃, 50-55℃ or 55-60℃.

[0055] The time of the heating and stirring is 1-2 h. For example, 1-1.5 h or 1.5-2 h.

[0056] The stirring rate of the stirring is 300-500 r / min. For example, 300-350 r / min, 350-400 r / min, 400-450 r / min or 450-500 r / min.

[0057] The time of the vacuum defoaming is 30-60 min. For example, 30-35 min, 35-40 min, 40-45 min, 45-50 min, 50-55 min or 55-60 min.

[0058] The pressure of the vacuum defoaming is -0.090 to -0.095 Mpa. For example, -0.090 to -0.091 Mpa, -0.091 to -0.092 Mpa, -0.092 to -0.093 Mpa, -0.093 to -0.094 Mpa or -0.094 to -0.095 Mpa.

[0059] The third aspect of the application provides a use of the moisture and heat aging resistant epoxy heat conductive structural adhesive in electronic devices, new energy automobile batteries and energy storage fields.

[0060] Example 1

[0061] Preparation of the moisture and heat aging resistant epoxy heat conductive structural adhesive:

[0062] (1) Bisphenol A type epoxy resin, phenolic epoxy resin F51, naphthalene type epoxy resin EBA-65, toughening agent (polyurethane) were weighed in a ratio of 60:15:20:5, blended and heated at 40°C for 1h at a rotation speed of 300r / min, vacuum defoaming treatment was carried out at -0.095Mpa for 40min, and then naturally cooled to room temperature after sealing to obtain a composite epoxy resin, which was ready for use;

[0063] (2) 100g of spherical Al2O3 with different particle sizes and 2g of γ-glycidoxypropyltrimethoxysilane were added into a flask containing 200g of anhydrous ethanol and uniformly mixed, and the pH was adjusted to 3-4 with acetic acid; then the flask was placed in a 60°C water bath environment and mechanically stirred, and a condensation reflux device was installed on the top, the stirring speed was 200r / min, and the reaction time was 5-6h; after the reaction was completed, the powder after filtration was repeatedly washed with anhydrous ethanol for 3 times, and then placed in a blast drying oven, the drying oven temperature was 120°C, and the drying time was 4h, finally the surface-treated Al2O3 powder particles, i.e. modified alumina, were obtained; the surface treatment of AlN particles was the same as the above step;

[0064] (3) The modified fillers with different median particle sizes (mass ratio of 1μm Al2O3:40μm Al2O3:90μm Al2O3:5μm AlN:15μm AlN:60μm AlN=5:16:47:2:10:20) were weighed according to the ratio, three-dimensionally mixed for 2-3h to obtain a composite heat-conducting filler, which was ready for use;

[0065] (4) The composite heat-conducting filler and diluent (polypropylene glycol diglycidyl ether) were sequentially added into the composite epoxy resin matrix in a ratio of 18:2:120, and then dispersed and mixed by a homogenizer, and vacuum defoaming treatment was carried out (800r / min, 15min, -0.095MPa) to obtain a uniform A component slurry;

[0066] (5) The curing agent (polythiol QE-340M), accelerator (polyetheramine D2000) and composite heat-conducting filler were sequentially added into a homogenizer in a ratio of 15:9:168, and mixed at high speed under vacuum to obtain a uniform B component slurry (800r / min, 15min, -0.095MPa);

[0067] (6) The prepared A and B component slurries were equally divided by volume into a two-component glue cylinder for storage, and a moisture and heat resistant epoxy heat-conducting structural adhesive was obtained, which could be used subsequently with a dispensing equipment and sample preparation.

[0068] Example 2

[0069] Preparation of a moisture and heat resistant epoxy heat-conducting structural adhesive:

[0070] (1) Bisphenol A type epoxy resin, phenolic epoxy resin F51, naphthalene type epoxy resin EBA-65, toughening agent (polyurethane) were weighed according to the ratio of 68:14:12:6, blended and heated at 40℃ for 2h at a speed of 500r / min, vacuum defoaming treatment was carried out at -0.095Mpa for 60min, and then naturally cooled to room temperature after sealing to obtain a composite epoxy resin, which was ready for use;

[0071] (2) 100g of spherical Al2O3 with different particle sizes and 2g of γ-glycidoxypropyltrimethoxysilane were added into a flask containing 200g of anhydrous ethanol and uniformly mixed, and the pH was adjusted to 3-4 with acetic acid; then the flask was placed in a 60℃ water bath environment and mechanically stirred, and a condensation reflux device was installed on the top, the stirring speed was 200r / min, and the reaction time was 5-6h; after the reaction was completed, the powder after filtration was repeatedly washed with anhydrous ethanol for 3 times, and then placed in a blast drying oven, the drying oven temperature was 120℃, and the drying time was 4h, finally the surface treated Al2O3 powder particles, i.e. modified alumina, were obtained; the surface treatment of AlN particles was the same as the above step;

[0072] (3) The modified fillers with different median particle sizes were weighed according to the ratio (mass ratio of 1μm Al2O3:40μm Al2O3:90μm Al2O3:5μm AlN:15μm AlN:60μm AlN=6:20:38:3:13:20), and three-dimensional mixing treatment was carried out for 2-3h to obtain a composite heat-conducting filler, which was ready for use;

[0073] (4) The composite heat-conducting filler and diluent (polypropylene glycol diglycidyl ether) were sequentially added into the composite epoxy resin matrix according to the ratio of 18:4:144, and then dispersed and mixed by a homogenizer, and vacuum defoaming treatment was carried out (1000r / min, 20min, -0.095MPa) to obtain a uniform A component slurry;

[0074] (5) The curing agent (polythiol QE-340M), accelerator (polyether amine D2000) and composite heat-conducting filler were sequentially added into a homogenizer according to the ratio of 18:12:210, and mixed uniformly under vacuum condition (1000r / min, 20min, -0.095MPa) to obtain a uniform B component slurry;

[0075] (6) The prepared A and B component slurries were equally divided into a two-component glue cylinder for storage, and a moisture and heat resistant epoxy heat-conducting structural adhesive was obtained, which could be used and sample prepared by subsequent dispensing equipment.

[0076] Example 3

[0077] Preparation of a moisture and heat resistant epoxy heat-conducting structural adhesive:

[0078] (1) Bisphenol A type epoxy resin, phenolic epoxy resin F51, naphthalene type epoxy resin EBA-65, toughening agent (polyurethane) were weighed according to the ratio of 70:10:14:6, blended and heated at 50°C for 1.5h at a speed of 400r / min, vacuum defoaming treatment was carried out at -0.095Mpa for 60min, and then naturally cooled to room temperature after sealing to obtain a composite epoxy resin, which was ready for use;

[0079] (2) 100g of spherical Al2O3 with different particle sizes and 2g of γ-glycidoxypropyltrimethoxysilane were added into a flask containing 200g of anhydrous ethanol and uniformly mixed, and the pH was adjusted to 3-4 with acetic acid; then the flask was placed in a 60°C water bath environment and mechanically stirred, and a condensation reflux device was installed on the top, the stirring speed was 200r / min, and the reaction time was 5-6h; after the reaction was completed, the powder was washed with anhydrous ethanol for 3 times, and then the filtered powder was placed in a blast drying oven, the drying oven temperature was 120°C, and the drying time was 4h, finally the surface-treated Al2O3 powder particles, i.e. modified alumina, were obtained; the surface treatment of AlN particles was the same as the above step;

[0080] (3) The modified fillers with different median particle sizes were weighed according to the ratio (mass ratio of 1μm Al2O3:40μm Al2O3:90μm Al2O3:5μm AlN:15μm AlN:60μm AlN=8:18:42:3:12:17), and three-dimensional mixing treatment was carried out for 2-3h to obtain a composite heat-conducting filler, which was ready for use;

[0081] (4) The composite heat-conducting filler and diluent (polypropylene glycol diglycidyl ether) were sequentially added into the composite epoxy resin matrix according to the ratio of 20:5:180, and then dispersed and mixed by a homogenizer, and vacuum defoaming treatment was carried out (1200r / min, 10min, -0.095MPa) to obtain a uniform A component slurry;

[0082] (5) The curing agent (polythiol QE-340M), accelerator (polyetheramine D2000) and composite heat-conducting filler were sequentially added into a homogenizer according to the ratio of 20:10:195, and mixed at high speed under vacuum to obtain a uniform B component slurry (1200r / min, 10min, -0.095MPa);

[0083] (6) The prepared A and B component slurries were equally divided into a two-component glue cylinder for storage, and a moisture and heat resistant epoxy heat-conducting structural adhesive was obtained, which could be used and sample prepared by subsequent dispensing equipment.

[0084] Example 4

[0085] Preparation of a moisture and heat resistant epoxy heat-conducting structural adhesive:

[0086] (1) Bisphenol A type epoxy resin, phenolic epoxy resin F51, naphthalene type epoxy resin EBA-65, toughening agent (polyurethane) were weighed according to the ratio of 72:10:10:8, blended and heated at 60℃ for 2h at a rotation speed of 300r / min, vacuum defoaming treatment was carried out at -0.095Mpa for 30min, and then naturally cooled to room temperature after sealing to obtain a composite epoxy resin, which was ready for use;

[0087] (2) 100g of spherical Al2O3 with different particle sizes and 2g of γ-glycidoxypropyltrimethoxysilane were added into a flask containing 200g of anhydrous ethanol and uniformly mixed, and the pH was adjusted to 3-4 with acetic acid; then the flask was placed in a 60℃ water bath environment and mechanically stirred, and a condensation reflux device was installed on the top, the stirring speed was 200r / min, and the reaction time was 5-6h; after the reaction was completed, the powder after filtration was repeatedly washed with anhydrous ethanol for 3 times, and then placed in a blast drying oven, the drying oven temperature was 120℃, and the drying time was 4h, finally the surface treated Al2O3 powder particles, i.e. modified alumina, were obtained; the surface treatment method of AlN particles was the same as the above step;

[0088] (3) The modified fillers with different median particle sizes (mass ratio of 1μm Al2O3:40μm Al2O3:90μm Al2O3:5μm AlN:15μm AlN:60μm AlN=10:18:37:4:15:16) were weighed according to the ratio, three-dimensionally mixed for 2-3h to obtain a composite heat-conducting filler, which was ready for use;

[0089] (4) The composite heat-conducting filler and diluent (polypropylene glycol diglycidyl ether) were sequentially added into the composite epoxy resin matrix according to the ratio of 25:4:172, and then dispersed and mixed by a homogenizer, and vacuum defoaming treatment was carried out (1500r / min, 10min, -0.095MPa) to obtain a uniform A component slurry;

[0090] (5) The curing agent (polythiol QE-340M), accelerator (polyether amine D2000) and composite heat-conducting filler were sequentially added into a homogenizer according to the ratio of 18:6:156, and mixed at high speed under vacuum to obtain a uniform B component slurry (1500r / min, 10min, -0.095MPa);

[0091] (6) The prepared A and B component slurries were equally divided by volume into a two-component glue cylinder for storage, and a moisture and heat resistant epoxy heat-conducting structural adhesive was obtained, which could be used and sample prepared by subsequent dispensing equipment.

[0092] Comparative Example 1

[0093] The difference from Example 1 is that no phenolic epoxy resin is added in the preparation of the composite epoxy resin in Comparative Example 1, and the remaining steps are the same as those in Example 1 to prepare the epoxy heat-conducting structural adhesive.

[0094] Comparative Example 2

[0095] The difference from Example 1 is that no naphthalene-type epoxy resin is added in the preparation of the composite epoxy resin in Comparative Example 2, and the remaining steps are the same as those in Example 1 to prepare the epoxy heat-conducting structural adhesive.

[0096] Comparative Example 3

[0097] The difference from Example 1 is that no toughening agent is added in the preparation of the composite epoxy resin in Comparative Example 1, and the remaining steps are the same as those in Example 1 to prepare the epoxy heat-conducting structural adhesive.

[0098] Comparative Example 4

[0099] The difference from Example 1 is that the composite heat-conducting filler in Comparative Example 4 is composed of only 1 μm Al2O3: 40 μm Al2O3: 90 μm Al2O3 = 5: 16: 47, and the remaining steps are the same as those in Example 1 to prepare the epoxy heat-conducting structural adhesive.

[0100] Performance test:

[0101] The material properties of the epoxy heat-conducting structural adhesives of Examples 1-4 and Comparative Examples 1-4 are shown in Table 1: (the damp-heat aging parameters are 85°C, 85% RH, and 100h)

[0102] Table 1

[0103]

[0104] From the above Table 1, it can be seen that the epoxy heat-conducting structural adhesives prepared in Examples 1-4 have high heat-conducting performance, good insulating performance, and high bonding performance, and their insulating and bonding performance is stable after aging test in a high-humidity and high-temperature environment. Compared with Example 1, Comparative Example 1 does not add phenolic resin, which greatly affects the mechanical properties and heat resistance of the system, and the bonding strength and volume resistivity are significantly reduced after damp-heat aging; Comparative Example 2 does not add naphthalene-type epoxy resin, which significantly reduces the damp-heat resistance of the system and reduces the comprehensive performance; Comparative Example 3 does not add a toughening agent, which reduces the mechanical properties; and Comparative Example 4 does not add aluminum nitride powder, which reduces the heat-conducting performance. The preferred mixed filling of the high-heat-conducting filler in the present patent can improve the heat-conducting performance of the system.

[0105] To sum up, the moisture and heat aging resistant epoxy heat conductive structural adhesive of the present application is prepared by using a composite epoxy resin, a diluent and a composite heat conductive filler to prepare the A component, using a curing agent, an accelerator and a composite heat conductive filler to prepare the B component, mixing the A component with the B component to obtain the moisture and heat aging resistant epoxy heat conductive structural adhesive, and the heat conductive structural adhesive prepared by the present application will not obviously decrease in insulation and bonding performance after long-term use in a high humidity and heat environment, and can significantly improve the stability and service life of electronic components.

[0106] Therefore, the present application effectively overcomes the shortcomings in the prior art and has high industrial utilization value.

[0107] The above embodiments only exemplarily illustrate the principles and effects of the present application, and are not used to limit the present application. Any person skilled in the art can modify or change the above embodiments without departing from the spirit and scope of the present application. Therefore, all equivalent modifications or changes completed by those skilled in the art without departing from the spirit and technical thought disclosed by the present application should be covered by the claims of the present application.

Claims

1. A moisture-heat resistant, thermally conductive epoxy structural adhesive, characterized in that, The raw material components include the following parts by weight: Component A: 18-25 parts of composite epoxy resin, 2-5 parts of diluent, and 120-180 parts of composite thermally conductive filler; Component B: 15-20 parts curing agent, 5-12 parts accelerator, 156-225 parts composite thermally conductive filler; The composite epoxy resin is obtained by blending raw materials including bisphenol A type epoxy resin, phenolic epoxy resin, naphthalene type epoxy resin and toughening agent; the weight ratio of bisphenol A type epoxy resin, phenolic epoxy resin, naphthalene type epoxy resin and toughening agent is 60~72:10~20:10~20:5~8; the phenolic epoxy resin is phenolic epoxy resin F51, the naphthalene type epoxy resin is naphthalene type epoxy resin EBA-65, and the toughening agent is polyurethane; The composite thermally conductive filler is obtained by mixing modified alumina and modified aluminum nitride of different particle sizes; the median particle size of the modified alumina is 1~100μm, the median particle size of the modified aluminum nitride is 1~70μm, and the weight ratio of the modified alumina to the modified aluminum nitride is 57~77:27~39.

2. The epoxy thermally conductive structural adhesive resistant to damp heat aging according to claim 1, characterized in that, The modified alumina is alumina coated with a coupling agent; And / or, the modified aluminum nitride is aluminum nitride coated with a coupling agent.

3. The epoxy thermally conductive structural adhesive resistant to damp heat aging according to claim 2, characterized in that, The diluent is polypropylene glycol diglycidyl ether; And / or, the coupling agent is γ-glycidoxypropyltrimethoxysilane; And / or, the curing agent is polythiol QE-340M; And / or, the accelerator is polyetheramine D2000.

4. A method for preparing an epoxy thermally conductive structural adhesive resistant to damp heat aging according to any one of claims 1 to 3, characterized in that, Includes the following steps: (1) The composite epoxy resin, diluent and composite thermally conductive filler are dispersed and mixed in a homogenizer, and the slurry of component A is obtained after vacuum defoaming treatment; (2) The curing agent, accelerator and composite thermally conductive filler are mixed evenly in a homogenizer under vacuum to obtain the slurry of component B; (3) Mix the slurry of component A and the slurry of component B in a 1:1 volume ratio to obtain the epoxy thermally conductive structural adhesive that is resistant to humid heat aging.

5. The method for preparing the hygrothermal aging resistant epoxy thermally conductive structural adhesive according to claim 4, characterized in that, In step (1), the rotational speed of the homogenizer is 800~1500 r / min; And / or, in step (1), the dispersion and mixing time is 10~30 min; And / or, in step (1), the pressure of the vacuum is -0.090 to -0.095 MPa; And / or, in step (2), the rotational speed of the homogenizer is 800~1500 r / min; And / or, in step (2), the mixing time is 10~30 min; And / or, in step (2), the pressure of the vacuum is -0.090 to -0.095 MPa.

6. The method for preparing the hygrothermal aging resistant epoxy thermally conductive structural adhesive according to claim 4, characterized in that, The composite epoxy resin mentioned in step (1) is obtained by mixing raw materials including bisphenol A type epoxy resin, phenolic epoxy resin, naphthalene type epoxy resin and toughening agent, heating and stirring, and then performing vacuum defoaming treatment.

7. The method for preparing the hygrothermal aging resistant epoxy thermally conductive structural adhesive according to claim 6, characterized in that, The heating and stirring temperature is 40~60℃; And / or, the heating and stirring time is 1-2 hours; And / or, the stirring rate of the heating and stirring is 300~500 r / min; And / or, the vacuum defoaming time is 30~60 min; And / or, the pressure of the vacuum defoaming is -0.090 to -0.095 MPa.

8. The application of an epoxy thermally conductive structural adhesive resistant to humid heat aging according to any one of claims 1 to 3 in the fields of new energy vehicles, electronic devices, and energy storage.

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