A kind of high temperature resistant heat conductive epoxy potting glue for motor and preparation method thereof

Abstract

The present invention provides a high temperature resistant heat conductive epoxy potting glue for motors, which relates to the technical field of epoxy potting glue. The epoxy potting glue is composed of component A and component B. Component A includes 100 parts of a first bisphenol A epoxy resin, 10 to 30 parts of polyimide, 80 to 150 parts of heat resistant novolac epoxy resin, 40 to 80 parts of heat resistant multifunctional epoxy resin, 10 to 20 parts of multifunctional epoxy glycidyl ether, and 50 to 100 parts of ozone modified alumina; component B includes 100 parts of an amine curing agent and 0 to 10 parts of a second bisphenol A epoxy resin. The prepared epoxy potting glue has a glass transition temperature (Tg value) of 200 to 211°C, a thermal conductivity of 0.81 to 0.96 W / K·m, a Shore D hardness of 94 to 98, a compressive strength of 207 to 228 MPa, and a volume curing shrinkage of 1.2 to 1.4%.

Description

Technical Field

[0001] The invention belongs to the technical field of epoxy potting adhesives, and in particular relates to a high temperature resistant heat conductive epoxy potting adhesive for motors and a preparation method thereof. Background Art

[0002] With the improvement of motor capacity, power, voltage and running speed, higher requirements are put forward for the insulation performance of motor coils. For example, the power of the test traction motor produced by Wuxi Zhongdian Motor reaches 70MW, the voltage level reaches 18KV, the running speed reaches 3600rpm, and the product size This large-size, high-power motor has higher requirements on the insulation performance of the motor coil, such as high temperature resistance, thermal conductivity, mechanical properties and volume shrinkage of the product.

[0003] The cured epoxy resin has good mechanical properties, electrical insulation and good processability. It does not produce volatiles during curing and has a small shrinkage rate during molding. Therefore, high-power and high-speed motors with high-temperature resistant and thermally conductive epoxy potting glue and its products are widely used in electrical industry products. However, ordinary epoxy resins have low temperature resistance (Tg value between 120~150℃), low thermal conductivity (less than 0.2W / K·m) and large volume shrinkage (more than 3%), which makes it difficult to meet the requirements of the above motors.

[0004] In addition, epoxy potting adhesive for motors has the problem of filler sedimentation in actual applications, which affects the storage stability and shelf life of the product. Summary of the invention

[0005] Due to the deficiencies in thermal stability and mechanical properties of epoxy potting products in the prior art, as well as the defect that fillers are prone to sedimentation, the present invention provides a high-temperature resistant and thermally conductive epoxy potting for motors, which has high glass transition temperature and thermal conductivity, low volume shrinkage, and good storage stability.

[0006] The present invention solves the above technical problems through the following technical solutions.

[0007] The present invention provides a high temperature resistant heat conductive epoxy potting adhesive for motors, which is composed of component A and component B;

[0008] The component A comprises: 100 parts of a first bisphenol A epoxy resin, 10 to 30 parts of polyimide, 80 to 150 parts of a heat-resistant novolac epoxy resin, 40 to 80 parts of a heat-resistant multifunctional epoxy resin, 10 to 20 parts of multifunctional epoxy glycidyl ether, and 50 to 100 parts of ozone-modified alumina;

[0009] The component B includes 100 parts of an amine curing agent;

[0010] The molar ratio of oxygen to aluminum in the ozone-modified alumina is 1.520-1.545:1.

[0011] The raw materials for preparing the polyimide include: diaminodiphenyl ether and trimellitic anhydride;

[0012] The number average molecular weight of the polyimide is 3.2×10 4 ~6.5×10 4 Among them, polyimide with a larger molecular weight has better mechanical properties and thermal stability, but the increase in the molecular weight of the polyimide will increase the difficulty of dissolving the polyimide, resulting in an increase in the viscosity of the potting glue system. In addition, the compatibility of the polyimide with a larger molecular weight and the matrix resin (a mixture of a first bisphenol A epoxy resin, a heat-resistant novolac epoxy resin and a heat-resistant multifunctional epoxy resin) may be poor, which may cause the two phases to separate, affecting the storage stability and the performance of the final product. Therefore, the present invention selects a polyimide with a moderate molecular weight to ensure that a uniform blend is formed during the blending process, while maintaining good solubility and compatibility, reducing the viscosity of the epoxy potting glue system, and facilitating processing and use.

[0013] In the present invention, ozone-modified alumina is achieved by ozone oxidation. The oxygen content of the alumina after ozone oxidation increases. On the one hand, the particle size of the alumina is D50 between 10 and 30 μm, and the alumina has a narrow and uniform pore distribution and a relatively large specific surface area, which is crucial to improving its adsorption of ozone molecules; on the other hand, the hydroxyl groups on the surface of the alumina after ozone modification increase, and hydration reactions may occur to produce a hydroxide that is thermodynamically more stable than Al2O3, namely hydroxyl aluminum oxide. The pores between the alumina after ozone modification increase, the agglomeration phenomenon decreases, and the dispersibility is improved. In the system of the present invention, this helps to form a more uniform filling structure. This modification also improves the thermal conductivity of alumina, so the ratio of ozone-modified alumina in the present invention can be appropriately reduced.

[0014] In the present invention, the glass transition temperature (Tg value) of the high temperature resistant thermal conductive epoxy potting adhesive for the motor is 200-211°C.

[0015] In the present invention, the thermal conductivity of the high temperature resistant heat conductive epoxy potting glue for the motor is 0.81-0.96 W / K·m.

[0016] In the present invention, the Shore D hardness of the high temperature resistant thermal conductive epoxy potting adhesive for the motor is 94-98.

[0017] In the present invention, the compressive strength of the high temperature resistant thermal conductive epoxy potting adhesive for the motor is 207-228 MPa.

[0018] In the present invention, the volume curing shrinkage rate of the high temperature resistant thermal conductive epoxy potting adhesive for the motor is 1.2-1.4%.

[0019] In the present invention, the mass ratio of component A to component B is 100:8-15.

[0020] In the present invention, the first bisphenol A epoxy resin is a liquid bisphenol A epoxy resin, and its epoxy equivalent is 170-230 g / mol. Different epoxy equivalents will lead to different viscosities and epoxy values, and different crosslinking densities. In order to ensure that the overall performance indicators such as heat resistance and viscosity of the product are similar, the amounts of the heat-resistant novolac epoxy resin and the heat-resistant multifunctional epoxy resin are adjusted to make the comprehensive performance of the products similar.

[0021] In the present invention, the heat-resistant novolac epoxy resin is a phenol-type novolac epoxy resin and / or a bisphenol A-type novolac epoxy resin; wherein the epoxy equivalent of the heat-resistant novolac epoxy resin is 170-200 g / mol.

[0022] In the present invention, the heat-resistant multifunctional epoxy resin is at least one of a trifunctional alicyclic epoxy resin, a trifunctional aromatic epoxy resin and a tetrafunctional glycidylamine type epoxy resin.

[0023] Furthermore, the structural formula of the trifunctional cyclic epoxy resin is as follows:

[0024] ;

[0025] Furthermore, the structural formula of the trifunctional aromatic epoxy resin is as follows:

[0026] ;

[0027] Furthermore, the structural formula of the trifunctional aromatic epoxy resin is as follows:

[0028] .

[0029] In the present invention, the multifunctional epoxy glycidyl ether is at least one of ethylene glycol diglycidyl ether (CAS No.: 2224-15-9), butanediol diglycidyl ether (CAS No.: 2425-79-8), neopentyl glycol diglycidyl ether (CAS No.: 17557-23-2), resorcinol diglycidyl ether (CAS No.: 101-90-6), diglycidyl aniline (CAS No.: 2095-06-9), diglycidyl ether (CAS No.: 2238-07-5), trimethylolpropane triglycidyl ether (CAS No.: 30499-70-8), and glycerol triglycidyl ether (CAS No.: 13236-02-7).

[0030] In the present invention, multifunctional epoxy glycidyl ether is usually used as a diluent to reduce the viscosity of epoxy potting glue products. In the present invention, the addition of multifunctional epoxy glycidyl ether can not only promote the interaction between the matrix resin and the polyimide, but also can be used as a surfactant to improve the dispersibility of the ozone-modified alumina, and improve the compatibility between the filler and the matrix resin, which helps to improve the uniformity and overall performance of the final product. Among them, the compatibility of polyimide and the matrix resin is crucial to the thermal conductivity and mechanical properties of the final product, while the adhesion between polyimide and the matrix resin is weak, and multifunctional epoxy glycidyl ether can improve this bonding performance, thereby optimizing the interface compatibility of the two materials.

[0031] In the present invention, the component A may further include 3 to 6 parts of a wetting and dispersing agent and 2 to 4 parts of a defoaming agent.

[0032] In the present invention, the component B further comprises 0 to 10 parts of a second bisphenol A epoxy resin.

[0033] Furthermore, the wetting and dispersing agent is at least one of BYK-W9010, BYK-W9011, and AFCONA-7520.

[0034] Furthermore, the defoaming agent is at least one of BYK-066N, BYK-1790, and AFCONA-2270.

[0035] In the present invention, the component A is composed of 100 parts of a first bisphenol A epoxy resin, 5 to 30 parts of a polyimide, 80 to 150 parts of a heat-resistant novolac epoxy resin, 40 to 80 parts of a heat-resistant multifunctional epoxy resin, 10 to 20 parts of a multifunctional epoxy glycidyl ether, 50 to 100 parts of ozone-modified alumina, 3 to 6 parts of a wetting dispersant and 2 to 4 parts of a defoaming agent.

[0036] In the present invention, the second bisphenol A epoxy resin is a liquid bisphenol A epoxy resin, and its epoxy equivalent is 170-220 g / mol.

[0037] In the present invention, the amine curing agent is a diamine curing agent, preferably at least one of methylcyclohexanediamine (CAS No.: 13897-55-7), isophoronediamine (CAS No.: 2855-13-2), menthanediamine (CAS No.: 80-52-4), 4,4'-diaminodicyclohexylmethane (CAS No.: 1761-71-3), and 3,3'-dimethyl-4,4'-diaminodicyclohexylmethane (CAS No.: 6864-37-5).

[0038] The present invention also provides a method for preparing the high temperature resistant heat conductive epoxy potting adhesive for the motor, comprising mixing component A and component B.

[0039] Furthermore, the preparation method of the component A comprises the following preparation steps:

[0040] Premixing polyimide and ozone-modified alumina to obtain a composite thermally conductive filler;

[0041] heating a first bisphenol A epoxy resin, a heat-resistant novolac epoxy resin and a heat-resistant multifunctional epoxy resin to form a base resin;

[0042] Adding multifunctional epoxy glycidyl ether and a wetting and dispersing agent to a base resin to obtain a first mixture;

[0043] Add the composite thermal conductive filler and the defoaming agent to the first mixture and disperse them evenly.

[0044] The mixing device is a colloid mill, the mixing speed is 1500-2500 rpm, preferably 2000 rpm; the mixing time is 5-30 min.

[0045] The heating temperature is 60-80° C., and the heating process needs to be stirred at a speed of 200-600 rpm; the heating time is 10-30 min; and the heating needs to make the system completely transparent before adding other components.

[0046] The stirring speed for uniform dispersion is 600-2000 rpm, preferably 1000-1500 rpm; the time for uniform dispersion is 10-20 min.

[0047] Furthermore, the preparation method of the component B comprises the following steps: mixing an amine curing agent and a second bisphenol A epoxy resin to obtain the component B; wherein, after the mixing, the step of standing is also included, and the standing time is ≥24h.

[0048] In the present invention, the polyimide has good thermal stability and mechanical strength, and the addition of the polyimide can also enhance the thermal conductivity of the epoxy resin through physical mixing.

[0049] In the present invention, the composite thermally conductive filler used significantly improves its compatibility with the matrix resin through both chemical and physical mechanisms. When ozone-modified alumina is filled into the polyimide matrix, polyimide preliminarily fixes the ozone-modified alumina; polyimide has good compatibility with the matrix resin, and polyimide is used to evenly fill the ozone-modified alumina into the matrix resin, thereby building an efficient thermal conductive network in the final potting system. This network not only promotes the effective transfer of heat, but also reduces the pores between particles, thereby reducing the thermal resistance of the material. Therefore, this composite material not only improves the mechanical properties of the epoxy resin system, but also significantly improves its thermal stability. Furthermore, the method for preparing the high-temperature resistant thermally conductive epoxy potting glue for the motor also includes the steps of pretreating alumina and preparing polyimide:

[0050] 1) Pretreatment of alumina: Spherical alumina is ultrasonically treated in ammonia water, then heated in an ozone atmosphere, and vacuum dried to obtain ozone-modified alumina;

[0051] 2) Preparation of polyimide: The preparation method of the polyimide is to polymerize 4,4'-diaminodiphenyl and trimellitic anhydride, and then wash with water and dry;

[0052] In step 1), the particle size D50 of the spherical alumina is between 10 and 30 μm.

[0053] In step 1), the mass ratio of the spherical alumina to the ammonia water is 1:5-8.

[0054] In step 1), the pH of the ammonia water is 8 to 9. The alkaline condition of the ammonia water can increase the activity of the aluminum oxide and improve the oxidation efficiency.

[0055] In step 1), the ultrasonic treatment time is 2 to 5 hours, and the ultrasonic treatment is carried out under nitrogen protection.

[0056] In step 1), the concentration of ozone is controlled at 100-150 mg / L.

[0057] In step 1), the heating temperature is 30-40° C., and the heating time is 3-12 hours, preferably 4-8 hours.

[0058] In step 1), the vacuum drying is carried out under a pressure of 1-10 Pa, a temperature of 100-150° C. and a time of 3-5 h.

[0059] In step 2), the polymerization is carried out under nitrogen protection, the polymerization solvent is DMF (N,N-dimethylformamide, CAS No.: 68-12-2) or NMP (N-methylpyrrolidone, CAS No.: 872-50-4), and the base used in the polymerization is triethylamine.

[0060] In step 2), the water washing is a conventional operation in the art, for example, after polymerization, water is added for washing and then filtered, which is performed 2 to 3 times.

[0061] In step 2), the drying temperature is 100-130° C. and the drying time is 2-3 hours.

[0062] In step 2), the polymerization temperature is 80-120° C., preferably 100° C.; the polymerization time is 8-15 h, preferably 12 h; and the polymerization stirring speed is 2000-3000 rpm.

[0063] In the further step 2), the molar ratio of the 4,4'-diaminodiphenyl ether to the trimellitic anhydride is 1:1.0-1.2, and the molar ratio of the 4,4'-diaminodiphenyl ether to the triethylamine is 1:1.0-1.3.

[0064] In the further step 2), the concentration of the 4,4'-diaminodiphenyl ether in the solvent is 0.3-0.5 mol / L.

[0065] On the basis of being in accordance with the common sense in the art, the above-mentioned preferred conditions can be arbitrarily combined to obtain the preferred embodiments of the present invention.

[0066] Compared with the prior art, the present invention has the following beneficial effects:

[0067] 1. Optimization of thermal conductivity of alumina:

[0068] Ozone-modified alumina has a higher oxygen content, and its larger pores can reduce agglomeration and improve dispersibility, thereby optimizing the thermal conductivity of the product.

[0069] 2. Improved thermal stability and mechanical properties:

[0070] The composite thermal conductive filler enhances the interfacial adhesion between ozone-modified alumina and polyimide through chemical bonding, and physically improves the heat transfer efficiency of the material by building a thermal conductive network and reducing pores. Therefore, it not only improves the mechanical properties, but also enhances its thermal stability.

[0071] 3. Good system compatibility:

[0072] Multifunctional epoxy glycidyl ether can not only adjust the viscosity of the system, but also play the role of a surfactant, coordinating the compatibility of the resin matrix and filler in the system. The composition of component A is more uniform and stable, which improves its storage stability.

[0073] 4. Better thermal stability, thermal conductivity and mechanical properties:

[0074] The high temperature resistant heat conductive epoxy potting glue for motors prepared by the present invention has a glass transition temperature of 200-211° C., a thermal conductivity of 0.81-0.96 W / K·m, a Shore D hardness of 94-98, a compressive strength of 207-228 MPa, and a volume curing shrinkage of 1.2-1.4%, which makes the product suitable for packaging protection of equipment such as motors with strict requirements. DETAILED DESCRIPTION

[0075] In order to facilitate the understanding of the present invention, the present invention will be described more comprehensively and carefully in combination with preferred embodiments below, but the protection scope of the present invention is not limited to the following specific embodiments.

[0076] Unless otherwise defined, all professional terms used below have the same meanings as those generally understood by those skilled in the art. The professional terms used herein are only for the purpose of describing specific embodiments and are not intended to limit the scope of protection of the present invention.

[0077] The CAS numbers of some of the raw materials for preparing polyimide in the following examples are shown in Table 1:

[0078]

[0079] [Example 1]

[0080] 1. Preparation of raw materials

[0081] 1) Pretreatment of alumina: In a nitrogen atmosphere, spherical alumina with a particle size of D50 = 20 μm was added to ammonia water with a pH of 9 and ultrasonically treated for 3 hours. The mass ratio of alumina to ammonia water was 1:6. The alumina was then heated in 120 mg / L ozone (heated at 40°C for 6 hours). After drying at a vacuum degree of 5 Pa and a temperature of 130°C for 5 hours, ozone-modified alumina with an oxygen-aluminum molar ratio of 1.545:1 was obtained. The oxygen-aluminum ratio of the ozone-modified alumina can be measured by an elemental analyzer, and the molar ratio can be converted based on the experimental results.

[0082] 2) Preparation of polyimide: In a nitrogen atmosphere, dissolve 4,4'-diaminodiphenyl in anhydrous DMF at 0°C, then slowly add trimellitic anhydride, mix well, then slowly add triethylamine, and continue mixing for 10 minutes. Then raise the temperature to 80°C, stir at 2500 rpm, and polymerize for 12 hours. The molar ratio of 4,4'-diaminodiphenyl: trimellitic anhydride: triethylamine is 1:1.05:1.1.

[0083] The concentration of 4,4'-diaminodiphenyl ether in DMF is 0.5 mol / L. After the polymerization is completed, water is added for washing and then filtered, and the process is repeated three times. The mixture is vacuum dried at 130°C for 3 hours. The number average molecular weight of the prepared polyimide is 4.8×10 4 ~5.3×104 .

[0084] 2. Product formula

[0085] The components of this embodiment are composed of the following raw materials, and the mass ratio of component A to component B is 100:11.

[0086] (1) Component A includes: 100 parts of a first bisphenol A epoxy resin, 15 parts of a polyimide, 100 parts of a heat-resistant novolac epoxy resin, 50 parts of a heat-resistant multifunctional epoxy resin, 15 parts of a multifunctional epoxy glycidyl ether, 80 parts of an ozone-modified alumina, 4 parts of a wetting and dispersing agent, and 2 parts of a defoaming agent.

[0087] In this embodiment, the first bisphenol A epoxy resin is a liquid bisphenol A epoxy resin with an epoxy equivalent of 176-184 g / mol. The brand of the raw material is Nan Ya NPEL127.

[0088] In this embodiment, the heat-resistant novolac epoxy resin is a phenol-type novolac epoxy resin. The raw material model is F51.

[0089] In this embodiment, the heat-resistant multifunctional epoxy resin is a trifunctional cyclic epoxy resin, and the structural formula is as follows:

[0090] .

[0091] In this embodiment, the multifunctional epoxy glycidyl ether is resorcinol diglycidyl ether.

[0092] The wetting and dispersing agent in this embodiment is BYK-W9010.

[0093] The defoamer in this embodiment is AFCONA-2270.

[0094] (2) Component B includes 100 parts of an amine curing agent and 8 parts of a second bisphenol A epoxy resin.

[0095] In this embodiment, the amine curing agent is isophorone diamine.

[0096] In this embodiment, the second bisphenol A epoxy resin is a liquid bisphenol A epoxy resin with an epoxy equivalent of 176-184 g / mol. The brand of the raw material is Nan Ya NPEL127.

[0097] 3. Preparation method

[0098] The preparation steps of this embodiment are as follows:

[0099] S1. Preparation of Component A:

[0100] Premixing polyimide and ozone-modified alumina in a colloid mill for 10 minutes at a rotation speed of 2000 rpm to obtain a composite thermal conductive filler; heating a first bisphenol A epoxy resin, a heat-resistant novolac epoxy resin and a heat-resistant multifunctional epoxy resin to 80° C., stirring at 500 rpm for 20 minutes to form a matrix resin, which is completely transparent; adding multifunctional epoxy glycidyl ether and a wetting dispersant to the matrix resin, stirring to obtain a first mixture; adding a composite thermal conductive filler and a defoamer to the first mixture, stirring at 1200 rpm for 10 minutes to disperse evenly;

[0101] S2. Preparation of component B: The amine curing agent and the second bisphenol A epoxy resin are weighed and mixed according to the required ratio and allowed to stand for 24 hours to obtain the component B;

[0102] S3. Component A and component B are mixed in a mass ratio of 100:11 to obtain the high temperature resistant heat conductive epoxy potting adhesive for motors. In S1, S2 and S3, the mixing is conventional mechanical or manual mixing.

[0103] [Example 2]

[0104] 1. Preparation of raw materials

[0105] The raw materials used in this embodiment are the same as those in Example 1.

[0106] 2. Product formula

[0107] The components of this embodiment are composed of the following raw materials, and the mass ratio of component A to component B is 100:9.

[0108] (1) Component A comprises: 100 parts of a first bisphenol A epoxy resin, 15 parts of a polyimide, 80 parts of a heat-resistant novolac epoxy resin, 60 parts of a heat-resistant multifunctional epoxy resin, 10 parts of a multifunctional epoxy glycidyl ether, 70 parts of an ozone-modified alumina, 5 parts of a wetting and dispersing agent, and 3 parts of a defoaming agent.

[0109] In this embodiment, the first bisphenol A epoxy resin is a liquid bisphenol A epoxy resin with an epoxy equivalent of 184-184 g / mol. The grade of the raw material is Baling Petrochemical CYD128.

[0110] In this embodiment, the heat-resistant novolac epoxy resin is a phenol-type novolac epoxy resin. The raw material model is F48.

[0111] In this embodiment, the heat-resistant multifunctional epoxy resin is a trifunctional aromatic epoxy resin, and the structural formula is as follows:

[0112] .

[0113] In this embodiment, the multifunctional epoxy glycidyl ether is dibutyl glycidyl ether.

[0114] The wetting and dispersing agent in this embodiment is AFCONA-7520.

[0115] The defoamer in this embodiment is BYK-066N.

[0116] (2) Component B includes 100 parts of an amine curing agent and 10 parts of a second bisphenol A epoxy resin.

[0117] In this embodiment, the amine curing agent is methylcyclohexanediamine.

[0118] In this embodiment, the second bisphenol A epoxy resin is a liquid bisphenol A epoxy resin with an epoxy equivalent of 184-190 g / mol. The brand of the raw material is Nan Ya NPEL-128.

[0119] 3. Preparation method

[0120] The steps for preparing the product of this embodiment are the same as those of embodiment 1.

[0121] [Example 3]

[0122] 1. Preparation of raw materials

[0123] The raw materials used in this embodiment are the same as those in Example 1.

[0124] 2. Product formula

[0125] The components of this embodiment are composed of the following raw materials, and the mass ratio of component A to component B is 100:15.

[0126] (1) Component A includes: 100 parts of a first bisphenol A epoxy resin, 25 parts of a polyimide, 120 parts of a heat-resistant novolac epoxy resin, 70 parts of a heat-resistant multifunctional epoxy resin, 20 parts of a multifunctional epoxy glycidyl ether, 70 parts of an ozone-modified alumina, 6 parts of a wetting and dispersing agent, and 3 parts of a defoaming agent.

[0127] In this embodiment, the first bisphenol A epoxy resin is a liquid bisphenol A epoxy resin with an epoxy equivalent of 210-230 g / mol. The brand of the raw material is Nantong 6101.

[0128] In this embodiment, the heat-resistant novolac epoxy resin is a phenol-type novolac epoxy resin. The raw material model is F51.

[0129] In this embodiment, the heat-resistant multifunctional epoxy resin is a tetrafunctional glycidylamine type epoxy resin, and the structural formula is as follows:

[0130] .

[0131] In this embodiment, the multifunctional epoxy glycidyl ether is trimethylolpropane triglycidyl ether.

[0132] The wetting and dispersing agent in this embodiment is BYK-W9011.

[0133] The defoamer in this embodiment is BYK-1790.

[0134] (2) Component B includes: 100 parts of an amine curing agent and 2 parts of a second bisphenol A epoxy resin.

[0135] In this embodiment, the amine curing agent is 4,4'-diaminodicyclohexylmethane.

[0136] In this embodiment, the second bisphenol A epoxy resin is a liquid bisphenol A epoxy resin with an epoxy equivalent of 180-190 g / mol. The grade of the raw material is Baling Petrochemical CYD127.

[0137] 3. Preparation method

[0138] The product preparation method of this embodiment is the same as that of Example 1.

[0139] [Example 4]

[0140] 1. Preparation of raw materials

[0141] 1) Pretreatment of aluminum oxide: In a nitrogen atmosphere, spherical aluminum oxide with a particle size of D50 = 20 μm was added to ammonia water with a pH of 9 and ultrasonically treated for 3 hours, the mass ratio of aluminum oxide to ammonia water was 1:6, and then heated in ozone with a concentration of 100 mg / L (heated at 40°C for 6 hours); after drying at a vacuum degree of 5 Pa and a temperature of 130°C for 5 hours, ozone-modified aluminum oxide with an oxygen-aluminum molar ratio of 1.523:1 was obtained. This embodiment uses a lower concentration of ozone environment, and the content of ozone-modified aluminum oxide finally obtained is lower than that in Example 1.

[0142] 2) Preparation of polyimide: This step is the same as in Example 1.

[0143] 2. Product formula and 3. Preparation method are the same as in Example 1.

[0144] [Comparative Example 1]

[0145] This comparative example investigates the effect of the molecular weight of polyimide on epoxy potting adhesive.

[0146] 1. Preparation of raw materials

[0147] 1) Pretreatment of aluminum oxide: This step is the same as in Example 1.

[0148] 2) Preparation of polyimide:

[0149] The polymerization temperature was 100°C (80°C in Example 1) for 12 h, and the final product had a number average molecular weight of 6.7×10 4 ~7.9×10 4 of polyimide.

[0150] 2. Product formula and 3. Preparation method are the same as in Example 1. The number average molecular weight used in this comparative example is 6.7×10 4 ~7.9×10 4 Except for polyimide.

[0151] If the molecular weight of the polymer formed at high temperature is too large, the viscosity of the potting compound will increase and its solubility will be poor, and its compatibility with the matrix resin will deteriorate, resulting in two-phase separation; its poor fluidity will also make the preparation process and subsequent use process more difficult. Polyimide itself has excellent mechanical properties and thermal stability, but polyimide with too large a molecular weight will have lower reactivity when reacting with epoxy resin, thus affecting the performance of the potting compound after curing. See Table 3 for specific properties.

[0152] [Comparative Example 2]

[0153] This comparative example investigates the effect of the aluminum-oxygen molar ratio of aluminum oxide on the epoxy potting compound.

[0154] 1. Preparation of raw materials

[0155] 1) Pre-treatment of alumina: This comparative example directly uses 20 μm spherical alumina, the aluminum-oxygen molar ratio of which is 1.503:1, and the alumina is not ozonated.

[0156] 2) Preparation of polyimide: This step is the same as in Example 1.

[0157] 2. Product formula and 3. Preparation method are the same as in Example 1, except that the aluminum oxide used in this comparative example is 1.503:1 aluminum oxide.

[0158] The only difference between this comparative example and Example 1 is that the spherical alumina in this comparative example has a low aluminum-oxygen ratio, so the thermal conductivity and compatibility with this system are average.

[0159] [Comparative Example 3]

[0160] This comparative example investigates the effect of the order of adding materials in component A on the epoxy potting compound.

[0161] 1. Preparation of raw materials and 2. Product formulation are the same as in Example 2.

[0162] 3. Preparation method:

[0163] Except that the order of adding materials in S1 is different, as described below, the other steps are the same as those in Example 2.

[0164] S1. Preparation of component A: bisphenol A epoxy resin, polyimide, heat-resistant novolac epoxy resin and heat-resistant multifunctional epoxy resin weighed in the required proportion are heated to 80°C, stirred at 500 rpm for 20 minutes, and then functional epoxy glycidyl ether, wetting dispersant and defoaming agent are added, and stirred for 5 minutes; then ozone-modified alumina is added, and then dispersed evenly at a high speed of 1200 rpm, and the component A is obtained after 10 minutes.

[0165] In the above Example 2, polyimide and ozone-modified alumina are pre-mixed to form a uniform polymer / filler composite component, which may reduce the phase separation phenomenon caused by the mismatch of thermal expansion coefficients, thereby reducing the agglomeration phenomenon and making component A more uniform. The feeding method of this comparative example is the conventional feeding sequence in the art, that is, the base resin and polyimide are first mixed, and then the filler is added. The stability of the epoxy potting adhesive product finally obtained is poor, and its thermal stability and mechanical properties are affected to a certain extent. Therefore, polyimide may also have a certain synergistic effect with the thermal conductive filler.

[0166] Effect Example

[0167] The epoxy potting adhesive prepared in the above examples and comparative examples was subjected to various performance tests, and the specific test methods are shown in Table 2. The storage stability test method is to store the product at a temperature of 50°C and a humidity of 90%, and record the storage stability of the product to observe whether stratification or precipitation occurs during the process. In addition, component A and component B are stored separately and can be mixed according to the ratio when used.

[0168]

[0169] The performance test results of the epoxy potting adhesives prepared in the embodiments and comparative examples are shown in Table 3.

[0170]

[0171] Unless otherwise specified, various raw materials, reagents, instruments and equipment used in the present invention can be purchased from the market or prepared by existing methods. The specific embodiments described above further describe the purpose, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A high temperature resistant thermal conductive epoxy potting adhesive for motors, characterized in that: It is composed of component A and component B; The component A comprises: 100 parts of a first bisphenol A epoxy resin, 10 to 30 parts of polyimide, 80 to 150 parts of a heat-resistant novolac epoxy resin, 40 to 80 parts of a heat-resistant multifunctional epoxy resin, 10 to 20 parts of multifunctional epoxy glycidyl ether, 50 to 100 parts of ozone-modified alumina, 3 to 6 parts of a wetting dispersant and 2 to 4 parts of a defoaming agent; The component B comprises 100 parts of an amine curing agent and 0 to 10 parts of a second bisphenol A epoxy resin; the molar ratio of oxygen to aluminum in the ozone-modified alumina is 1.520 to 1.545:1; The number average molecular weight of the polyimide is 3.2×10 4 ~6.5×10 4 between; The preparation method of the component A comprises the following preparation steps: Premixing polyimide and ozone-modified alumina to obtain a composite thermally conductive filler; heating a first bisphenol A epoxy resin, a heat-resistant novolac epoxy resin and a heat-resistant multifunctional epoxy resin to form a base resin; Adding multifunctional epoxy glycidyl ether and a wetting and dispersing agent to a base resin to obtain a first mixture; Add the composite thermal conductive filler and the defoaming agent to the first mixture and disperse them evenly.

2. The high temperature resistant thermal conductive epoxy potting adhesive for motor according to claim 1, characterized in that: The glass transition temperature of the high temperature resistant heat conductive epoxy potting glue for the motor is 200-211°C; and / or, thermal conductivity of 0.81~0.96W / K·m; and / or, Shore D hardness of 94~98; and / or, a compressive strength of 207-228 MPa; And / or, the volume shrinkage upon curing is 1.2-1.4%.

3. The high temperature resistant thermal conductive epoxy potting adhesive for motor according to claim 1, characterized in that: The mass ratio of component A to component B is 100:8-15; And / or, the raw materials for preparing the polyimide include: diaminodiphenyl ether and trimellitic anhydride.

4. The high temperature resistant thermal conductive epoxy potting adhesive for motor according to claim 1, characterized in that: The first bisphenol A epoxy resin is a liquid bisphenol A epoxy resin, and its epoxy equivalent is 170-220 g / mol; The heat-resistant novolac epoxy resin is a phenol-type novolac epoxy resin and / or a bisphenol A-type novolac epoxy resin; wherein the epoxy equivalent of the heat-resistant novolac epoxy resin is 170-200 g / mol; The heat-resistant multifunctional epoxy resin is at least one of a trifunctional alicyclic epoxy resin, a trifunctional aromatic epoxy resin and a tetrafunctional glycidylamine type epoxy resin.

5. The high temperature resistant thermal conductive epoxy potting adhesive for motor according to claim 4, characterized in that: The structural formula of the trifunctional alicyclic epoxy resin is as follows: ； The structural formula of the trifunctional aromatic epoxy resin is as follows: or .

6. The high temperature resistant thermal conductive epoxy potting adhesive for motor according to claim 1, characterized in that: The component A is composed of 100 parts of a first bisphenol A epoxy resin, 10 to 30 parts of polyimide, 80 to 150 parts of a heat-resistant novolac epoxy resin, 40 to 80 parts of a heat-resistant multifunctional epoxy resin, 10 to 20 parts of multifunctional epoxy glycidyl ether, 50 to 100 parts of ozone-modified alumina, 3 to 6 parts of a wetting dispersant and 2 to 4 parts of a defoaming agent.

7. The high temperature resistant thermal conductive epoxy potting adhesive for motor according to claim 1, characterized in that: The second bisphenol A epoxy resin is a liquid bisphenol A epoxy resin, and its epoxy equivalent is 170-220 g / mol; The amine curing agent is a diamine curing agent.

8. The method for preparing the high temperature resistant thermal conductive epoxy potting adhesive for motors according to any one of claims 1 to 7, characterized in that: Mix component A and component B.

9. The method for preparing the high temperature resistant thermal conductive epoxy potting adhesive for motors according to claim 8, characterized in that: The preparation method of the component B comprises the following steps: The amine curing agent and the second bisphenol A epoxy resin are mixed to obtain the component B.

Images