A low-temperature curing electronic adhesive and its application

Abstract

The present invention relates to the field of electronic adhesive technology, in particular to the field of IPC C09J163, and further to a low-temperature curing electronic adhesive and its application. The electronic adhesive comprises a composite epoxy resin and a composite curing agent; the weight ratio of the composite epoxy resin to the composite curing agent is (15-25): (5-10). The electronic adhesive prepared by the present invention can be quickly cured at 0°C and has good adhesion, water resistance and toughness.

Description

Technical Field

[0001] The present invention relates to the technical field of electronic adhesives, in particular to the field of IPC C09J163, and further to a low-temperature curing electronic adhesive and an application thereof. Background Art

[0002] In recent years, with the impact of energy conservation, emission reduction and performance improvement, lightweight electronic devices have become a general trend; the electronic adhesive used for electronic component assembly has also had great application prospects. Among them, potting adhesives that can seal and bond electronic components and have excellent insulation and moisture resistance have received widespread attention. Potting adhesives in the prior art are mostly cured under heating conditions, which limits their curing environment.

[0003] Chinese patent CN 108611048 A discloses a dealcoholized silicone potting compound for dry-type transformers and its preparation method, wherein the silicone potting compound comprises component A, component B and component C, wherein the mass ratio of the three components is 100:3:3 to 100:10:10, wherein component A comprises 100 parts of terminal hydroxyl polysiloxane, 50 to 300 parts of filler, 0 to 80 parts of plasticizer, 1 to 8 parts of carbon black, 0.2 to 5 parts of surfactant and 0.1 to 1 part of curing accelerator by mass; component B comprises 100 parts of plasticizer, 5 to 100 parts of cross-linking agent, 0.01 to 3 parts of catalyst and 0 to 100 parts of coupling agent by mass; component C comprises 100 parts of plasticizer, 0 to 3 parts of catalyst and 0 to 100 parts of another coupling agent by mass. However, the technical solution can only achieve curing at room temperature of 25°C. Summary of the invention

[0004] The first aspect of the present invention provides a low-temperature curing electronic adhesive, comprising a composite epoxy resin and a composite curing agent; the weight ratio of the composite epoxy resin to the composite curing agent is (15-25): (5-10).

[0005] In some preferred embodiments, the composite epoxy resin comprises, by weight, at least: 30 to 70 parts of liquid bisphenol A epoxy resin, 70 to 100 parts of silicon powder, 10 to 25 parts of resorcinol diglycidyl ether, 15 to 20 parts of modifier, 1 to 3 parts of defoamer, and 2 to 4 parts of carbon black.

[0006] In some preferred embodiments, the viscosity of the liquid bisphenol A epoxy resin is less than 14000 cps / 25°C.

[0007] Preferably, the viscosity of the liquid bisphenol A epoxy resin is 9000-13500 cps / 25°C.

[0008] Further preferably, the total chlorine value of the liquid bisphenol A epoxy resin is ≤900 ppm.

[0009] More preferably, the epoxy equivalent of the liquid bisphenol A epoxy resin is 180 to 190 g / eq.

[0010] In some preferred embodiments, the composite epoxy resin further comprises, by weight, 20 to 60 parts of liquid bisphenol F epoxy resin.

[0011] Preferably, the viscosity of the liquid bisphenol F epoxy resin is less than 5000 cps / 25°C.

[0012] Preferably, the viscosity of the liquid bisphenol F epoxy resin is 3000-4500 cps / 25°C.

[0013] Preferably, the epoxy equivalent of the liquid bisphenol F epoxy resin is 165 to 180 g / eq.

[0014] Preferably, the mass ratio of the liquid bisphenol A epoxy resin to the liquid bisphenol F epoxy resin is (1.2-3):1.

[0015] The applicant discovered during the experiment that the electronic glue obtained after the curing reaction of the liquid bisphenol A epoxy resin with a viscosity of 9000-13500cps / 25°C and the modified polyamine curing agent specified in the present application has good bonding properties, but cannot achieve rapid curing at 0°C. In order to solve the above technical problems, the applicant discovered through a large number of creative experiments that when the total chlorine value of the liquid bisphenol A epoxy resin with a viscosity of 9000-13500cps / 25°C in the present application is ≤900ppm, and the liquid bisphenol F epoxy resin with a viscosity of <5000cps / 25°C is introduced, it can be combined with the modified polyamine curing agent specified in the present application to achieve rapid curing at 0°C and have good bonding properties; at the same time, the obtained electronic glue also has excellent toughness and water resistance. The applicant speculates that on the one hand, because the total chlorine value of the liquid bisphenol A epoxy resin is limited to ≤900ppm in the present application, it can avoid the influence of the hydrolyzable chlorine on the curing activity of the modified polyamine due to the formation of a complex with the modified polyamine curing agent of the present application, and can also avoid the influence of the hydrolyzable chlorine on the cured product, thereby improving the toughness and water resistance; on the other hand, because the liquid bisphenol F epoxy resin can reduce the viscosity of the composite epoxy resin system, promote rapid curing, and at the same time reduce the surface tension of the composite epoxy resin system, so that it can better wet the substrate surface, so that it can achieve 0°C curing while also having good adhesion.

[0016] In some preferred embodiments, the silicon micropowder is active silicon micropowder.

[0017] Preferably, the particle size of the active silicon powder is 1000-1500 mesh.

[0018] Preferably, the particle size of the active silicon powder is 1250 mesh.

[0019] In some preferred embodiments, the weight ratio of the active silicon powder to resorcinol diglycidyl ether is (9-10): (1-2).

[0020] The applicant discovered during the experiment that in the system of the present application, adding active silicon micropowder with a particle size of 1250 mesh can improve the shear strength and tensile strength of the electronic glue and reduce the water absorption rate to a certain extent, but even if the active silicon micropowder is added, the viscosity of the electronic glue cannot be avoided. In order to solve the above technical problems, the applicant unexpectedly discovered that when resorcinol diglycidyl ether is introduced into the system of the present application, especially when the weight ratio of active silicon micropowder and resorcinol diglycidyl ether is (9-10): (1-2), not only can the viscosity of the electronic glue be reduced, but also the electronic glue can be quickly cured at 0°C to ensure its toughness. The applicant speculates that under this condition, while resorcinol diglycidyl ether destroys the ordered structure of the resin in the original electronic glue system and reduces the viscosity of the electronic glue system, the epoxy group it carries can quickly participate in the curing reaction, and can avoid the problem of reduced toughness due to resorcinol diglycidyl ether increasing the crosslinking density of the electronic glue.

[0021] In some preferred embodiments, the modifier is a modified nitrile rubber, and the modified nitrile rubber is selected from at least one of an adduct of bisphenol A glycidyl ether and a carboxyl-terminated nitrile rubber elastomer and an adduct of bisphenol A epoxy resin and a carboxyl-terminated nitrile rubber.

[0022] Preferably, the modified nitrile rubber is an adduct of bisphenol A glycidyl ether and carboxyl-terminated nitrile rubber elastomer.

[0023] Preferably, the viscosity of the adduct of bisphenol A glycidyl ether and carboxyl-terminated nitrile rubber elastomer is 300,000-600,000 cps / 25° C., and the epoxy equivalent is 325-375 g / eq.

[0024] The applicant further discovered during the experiment that when active silicon powder and resorcinol diglycidyl ether are added to the system of the present application, the electronic adhesive can be quickly cured at 0°C and have a low viscosity. At the same time, the crosslinking density of the electronic adhesive system can be increased due to the addition of resorcinol diglycidyl ether. Although the weight ratio of active silicon powder and resorcinol diglycidyl ether is controlled to be (9-10): (1-2), the problem of reduced toughness due to increased crosslinking density of the electronic adhesive by resorcinol diglycidyl ether can be avoided. However, the toughness of the electronic adhesive prepared by the system of the present application needs to be further improved. In order to further improve the toughness of the electronic adhesive, the applicant unexpectedly discovered that when an adduct of bisphenol A glycidyl ether with a viscosity of 300,000-600,000 cps / 25°C and an epoxy equivalent of 325-375 g / eq and a carboxyl-terminated nitrile rubber elastomer is added, not only the toughness of the electronic adhesive can be improved, but also the water absorption rate of the electronic adhesive can be avoided.

[0025] In some preferred embodiments, the defoaming agent is a defoaming agent that does not contain silicone.

[0026] In some preferred embodiments, the composite curing agent comprises, by weight: 35 to 45 parts of modified polyamine curing agent and 1 to 5 parts of accelerator.

[0027] Preferably, the modified polyamine curing agent has an amine value of 500-700 mgKOH / g and a viscosity of 50-200 cps / 25°C.

[0028] Preferably, the modified polyamine curing agent has an amine value of 550-650 mgKOH / g, a viscosity of 60-150 cps / 25° C., and a model of Ancamine 2758 produced by Evonik of Germany.

[0029] Preferably, the accelerator is a tertiary amine curing agent.

[0030] The applicant has found through a large number of creative experiments that when the composite curing agent in the system of the present application is a modified polyamine curing agent, and when the amine value of the modified polyamine curing agent is 550-650 mgKOH / g, the viscosity is 60-150 cps / 25°C, and the model is German Evonik Ancamine 2758, it can work together with the liquid bisphenol A epoxy resin and liquid bisphenol F epoxy resin in the present application to achieve rapid curing at 0°C and have good shear strength. The applicant speculates that this is because the modified structure of the curing agent can form a network molecular structure with the liquid bisphenol A epoxy resin and liquid bisphenol F epoxy resin of the present application, increasing the cross-linking density, and thus improving the shear strength; at the same time, the modified structure of the curing agent may also introduce flexible segments and multiple highly active promoting groups, reducing the activation energy of the system, thereby reacting with the epoxy group faster, improving the degree of curing, and making it quickly cured at 0°C; and it has a lower viscosity and can be used for potting.

[0031] Preferably, the preparation method of the low-temperature curing electronic adhesive is: firstly weigh the raw materials of the composite epoxy resin and the raw materials of the composite curing agent according to weight; then mix the composite epoxy resin and the composite curing agent, stir them evenly, and then degas.

[0032] A second aspect of the present invention provides an application of a low-temperature curing electronic adhesive for waterproof sealing of automotive electronic components, sensors, and controllers.

[0033] Beneficial effects:

[0034] 1. When the total chlorine value of the liquid bisphenol A epoxy resin with a viscosity of 9000-13500cps / 25°C in this application is ≤900ppm, and a liquid bisphenol F epoxy resin with a viscosity of <5000cps / 25°C is introduced, it can be quickly cured at 0°C in combination with the specific modified polyamine curing agent of this application, and has good bonding properties; at the same time, the obtained electronic glue also has excellent toughness and water resistance.

[0035] 2. The system of this application introduces resorcinol diglycidyl ether, especially when the weight ratio of active silica powder to resorcinol diglycidyl ether is (9-10): (1-2), which can not only reduce the viscosity of the electronic adhesive, but also ensure that the electronic adhesive can be quickly cured at 0°C to ensure its toughness.

[0036] 3. In the present application, when the modifier is modified nitrile rubber, the modified nitrile rubber is an adduct of bisphenol A glycidyl ether and a terminal carboxyl nitrile rubber elastomer, and the viscosity of the adduct of bisphenol A glycidyl ether and a terminal carboxyl nitrile rubber elastomer is 300,000 to 600,000 cps / 25°C and the epoxy equivalent is 325 to 375 g / eq, while ensuring that the electronic glue has a low viscosity and can be used for potting, the toughness of the electronic glue can be improved and the water absorption rate of the electronic glue can be avoided to increase.

[0037] 4. The defoaming agent selected in this application is a defoaming agent that does not contain silicone, and will not affect the film-forming properties and adhesion of the electronic adhesive at 0°C while defoaming.

[0038] 5. When the composite curing agent in the system of the present application is a modified polyamine curing agent, and when the amine value of the modified polyamine curing agent is 550-650 mgKOH / g, the viscosity is 60-150 cps / 25°C, and the model is German Evonik Ancamine 2758, it works together with the liquid bisphenol A epoxy resin and liquid bisphenol F epoxy resin in the present application to achieve rapid curing at 0°C and have good shear strength, and has a low viscosity, and can be used for potting. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 This is a photograph of the appearance of the electronic glue prepared in Example 1 of the present invention before being immersed in water.

[0040] Figure 2 This is a photograph of the appearance of the electronic glue prepared in Example 1 of the present invention immersed in water. DETAILED DESCRIPTION

[0041] Example 1

[0042] Embodiment 1 provides a low-temperature curing electronic adhesive, comprising a composite epoxy resin and a composite curing agent; the weight ratio of the composite epoxy resin to the composite curing agent is 20:7.

[0043] The composite epoxy resin comprises, by weight: 55 parts of liquid bisphenol A epoxy resin, 25 parts of liquid bisphenol F epoxy resin, 90 parts of silicon micropowder, 20 parts of resorcinol diglycidyl ether, 18 parts of modifier, 3 parts of defoamer and 2 parts of carbon black.

[0044] The liquid bisphenol A epoxy resin has a viscosity of 9000-13500 cps / 25° C., a total chlorine value of ≤900 ppm, and an epoxy equivalent of 180-190 g / eq. It was purchased from Shanghai Kaiyin Chemical Co., Ltd., model: 828K-1.

[0045] The viscosity of the liquid bisphenol F epoxy resin is 3000-4500 cps / 25° C., the epoxy equivalent is 165-180 g / eq, and the model is DIC EXA-830-CRP epoxy resin.

[0046] The silicon micropowder is active silicon micropowder.

[0047] The particle size of the active silicon micropowder is 1250 mesh, and it is purchased from Xinyi Hongrun Quartz Silica Micropowder Co., Ltd.

[0048] The modifier is modified nitrile rubber, and the modified nitrile rubber is an addition product of bisphenol A glycidyl ether and terminal carboxyl nitrile rubber elastomer.

[0049] The adduct of bisphenol A glycidyl ether and carboxyl-terminated nitrile rubber elastomer has a viscosity of 300,000 to 600,000 cps / 25° C. and an epoxy equivalent of 325 to 375 g / eq. It was purchased from Shenzhen Jiadida New Material Technology Co., Ltd., model number: 861340.

[0050] The defoamer is a defoamer that does not contain silicone, model: BYK053.

[0051] The composite curing agent comprises, by weight, 40 parts of modified polyamine curing agent and 1 part of accelerator.

[0052] The modified polyamine curing agent has an amine value of 550-650 mgKOH / g, a viscosity of 60-150 cps / 25° C., and a model of Ancamine 2758 produced by Evonik of Germany.

[0053] The accelerator is DMP30.

[0054] The preparation method of the low-temperature curing electronic adhesive is as follows: firstly, various raw materials of the composite epoxy resin and various raw materials of the composite curing agent are weighed according to weight; then, the composite epoxy resin and the composite curing agent are mixed and stirred evenly, and then degassed to obtain the electronic adhesive.

[0055] The invention discloses an application of low-temperature curing electronic adhesive for waterproof sealing of automotive electronic components, sensors and controllers.

[0056] Example 2

[0057] Embodiment 2 provides a low-temperature curing electronic adhesive, comprising a composite epoxy resin and a composite curing agent; the weight ratio of the composite epoxy resin to the composite curing agent is 20:7.

[0058] The composite epoxy resin comprises, by weight: 53 parts of liquid bisphenol A epoxy resin, 22 parts of liquid bisphenol F epoxy resin, 95 parts of silicon micropowder, 25 parts of resorcinol diglycidyl ether, 18 parts of modifier, 3 parts of defoamer and 3 parts of carbon black.

[0059] The liquid bisphenol A epoxy resin has a viscosity of 9000-13500 cps / 25° C., a total chlorine value of ≤900 ppm, and an epoxy equivalent of 180-190 g / eq. It was purchased from Shanghai Kaiyin Chemical Co., Ltd., model: 828K-1.

[0060] The viscosity of the liquid bisphenol F epoxy resin is 3000-4500 cps / 25° C., the epoxy equivalent is 165-180 g / eq, and the model is DIC EXA-830-CRP epoxy resin.

[0061] The silicon micropowder is active silicon micropowder.

[0062] The particle size of the active silicon micropowder is 1250 mesh, and it is purchased from Xinyi Hongrun Quartz Silica Micropowder Co., Ltd.

[0063] The modifier is modified nitrile rubber, and the modified nitrile rubber is an addition product of bisphenol A glycidyl ether and terminal carboxyl nitrile rubber elastomer.

[0064] The adduct of bisphenol A glycidyl ether and carboxyl-terminated nitrile rubber elastomer has a viscosity of 300,000 to 600,000 cps / 25° C. and an epoxy equivalent of 325 to 375 g / eq. It was purchased from Shenzhen Jiadida New Material Technology Co., Ltd., model number: 861340.

[0065] The defoamer is a defoamer that does not contain silicone, model: BYK053.

[0066] The composite curing agent includes, by weight: 43 parts of modified polyamine curing agent and 1.1 parts of accelerator.

[0067] The modified polyamine curing agent has an amine value of 550-650 mgKOH / g, a viscosity of 60-150 cps / 25° C., and a model of Ancamine 2758 produced by Evonik of Germany.

[0068] The accelerator is DMP30.

[0069] The preparation method of the low-temperature curing electronic adhesive is as follows: firstly, various raw materials of the composite epoxy resin and various raw materials of the composite curing agent are weighed according to weight; then, the composite epoxy resin and the composite curing agent are mixed and stirred evenly, and then degassed to obtain the electronic adhesive.

[0070] The invention discloses an application of low-temperature curing electronic adhesive for waterproof sealing of automotive electronic components, sensors and controllers.

[0071] Comparative Example 1

[0072] Comparative Example 1 provides a low-temperature curing electronic adhesive and its application. The specific implementation method is the same as that of Example 1, except that the liquid bisphenol F epoxy resin is replaced by Nan Ya NPEF-170 liquid bisphenol F epoxy resin.

[0073] Comparative Example 2

[0074] Comparative Example 2 provides a low-temperature curing electronic adhesive and its application. Its specific implementation method is the same as that of Example 1, except that Ancamine 2758 from Evonik of Germany is replaced by a modified fatty amine curing agent purchased from Wuxi Pinhua Chemical Co., Ltd., model: 593#, with an amine value of 500-600 mgKOH / g and a viscosity of 50-150 cps / 25°C.

[0075] Comparative Example 3

[0076] Comparative Example 3 provides a low-temperature curing electronic adhesive and its application. The specific implementation method is the same as that of Example 1, except that resorcinol diglycidyl ether is replaced by butanediol diglycidyl ether.

[0077] Performance Testing:

[0078] 1. The test items and test methods of the electronic glue prepared in Example 1 before curing are shown in Table 1.

[0079] 2. The test items and test methods after curing of Examples 1 to 2 and Comparative Examples 1 to 3 are shown in Table 2; the appearance photos of the electronic glue before immersion in water during the water absorption test are shown in Table 2. Figure 1 As shown; the appearance of the electronic glue immersed in water is shown Figure 2 shown.

[0080] Test results:

[0081] Table 1

[0082]

[0083]

[0084] Table 2

[0085]

[0086] The water absorption test conditions: temperature 23±2℃; time 24h (complete immersion)

[0087] Water absorption rate = (m 2 -m 1 / m 1 )×100%,m 1 : The mass of the sample before water absorption, g; m 2 : The mass of the sample after water absorption, g.

Claims

1. A low temperature curing electronic adhesive, characterized in that: It comprises a composite epoxy resin and a composite curing agent; the weight ratio of the composite epoxy resin to the composite curing agent is (15-25): (5-10); The composite epoxy resin comprises, by weight, at least: 30-70 parts of liquid bisphenol A epoxy resin, 20-60 parts of liquid bisphenol F epoxy resin, 70-100 parts of silicon powder, 10-25 parts of resorcinol diglycidyl ether, 15-20 parts of modifier, 1-3 parts of defoamer, and 2-4 parts of carbon black; The composite curing agent comprises, by weight: 35-45 parts of a modified polyamine curing agent and 1-5 parts of an accelerator; The viscosity of the liquid bisphenol A epoxy resin is less than 14000 cps; the total chlorine value of the liquid bisphenol A epoxy resin is less than 900 ppm; The model of the liquid bisphenol F epoxy resin is: DIC EXA-830-CRP epoxy resin; The model of the modified polyamine curing agent is Ancamine 2758 produced by Evonik of Germany.

2. The low temperature curing electronic adhesive according to claim 1, characterized in that: The modifier is modified nitrile rubber; the modified nitrile rubber is an addition product of bisphenol A glycidyl ether and carboxyl-terminated nitrile rubber elastomer.

3. The low temperature curing electronic adhesive according to claim 2, characterized in that: The viscosity of the adduct of bisphenol A glycidyl ether and carboxyl-terminated nitrile rubber elastomer is 300,000-600,000 cps, and the epoxy equivalent is 325-375 g / eq.

4. An application of the low-temperature curing electronic adhesive according to any one of claims 1 to 3, characterized in that: Used for waterproof sealing of automotive electronic components, sensors and controllers.

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