High-viscosity epoxy resin adhesive and preparation method thereof

Abstract

The invention discloses a high-viscosity epoxy resin adhesive, and relates to the technical field of epoxy resin adhesives. The adhesive is prepared from the following raw material components: 80-100 parts of modified epoxy resin; 10 to 20 parts of an epoxy diluent; 0.5 to 1 part of a defoaming agent; 1-3 parts of a coupling agent; 7-15 parts of a composite curing agent; 2-10 parts of an accelerant; 50-100 parts of filler silicon dioxide; the composite curing agent comprises a first curing agent and a second curing agent, and the first curing agent and the second curing agent are microcapsule curing agents; the wall material of the first curing agent is thermoplastic resin, and the core material of the first curing agent is dicyandiamide; the wall material of the second curing agent is thermoplastic resin, the core material of the second curing agent is an imidazole derivative, and the imidazole derivative comprises one of 2-methylimidazole, 2-phenyl-4-methylimidazole and benzimidazole; by adopting the technical scheme provided by the invention, the bonding strength to materials such as PET (Polyethylene Terephthalate) and LCP (Liquid Crystal Polymer) can be effectively improved.

Description

Technical Field

[0001] The present application relates to the technical field of epoxy resins, and in particular to a high-viscosity epoxy resin adhesive and a preparation method thereof. Background Art

[0002] Commonly used epoxy resin adhesives are two-component or multi-component, and need to be formulated before use. In some application fields, due to the small amount of glue dispensed, high mixing requirements before use are required, otherwise it is easy to affect the final bonding effect. Compared with two-component adhesives, single-component epoxy does not have mixing problems. Latent curing agent is added to epoxy resin, and the reaction begins when heated to a certain temperature. It is widely used in the microelectronics industry.

[0003] The current one-component epoxy resin adhesives have the following problems: First, the adhesion to some specific materials is poor, such as PET. PET is a hydrophobic material with fewer surface functional groups, so it has poor compatibility with general resin adhesives. Therefore, the adhesion of traditional one-component epoxy resin adhesives to PET materials is weak; second, the resin must be heated before using the adhesive. Currently, traditional adhesives generally need to heat the adhesive temperature to above 130°C to better achieve the breaking of the latent curing agent and achieve curing. The temperature and time requirements are high, and long-term high-temperature heating also affects the adhesion performance of the resin. Summary of the invention

[0004] In order to solve the above technical problems, the purpose of the present application is to provide a high-viscosity epoxy resin adhesive and a preparation method thereof.

[0005] In a first aspect, the present application provides a high viscosity epoxy resin adhesive, which is made from the following raw material components:

[0006] Made from the following raw materials:

[0007]

[0008]

[0009] The composite curing agent includes a first curing agent and a second curing agent, wherein the first curing agent and the second curing agent are both microcapsule curing agents; the wall material of the first curing agent is a thermoplastic resin, and the core material is dicyandiamide; the wall material of the second curing agent is a thermoplastic resin, and the core material is an imidazole derivative, and the imidazole derivative includes one of 2-methylimidazole, 2-phenyl-4-methylimidazole, and benzimidazole.

[0010] Preferably, the thermoplastic resin includes one of polycarbonate, polyamide, polypropylene and polyvinyl chloride.

[0011] Preferably, the particle size of the first curing agent and the second curing agent is 5-8 μm.

[0012] Preferably, the ratio of the first curing agent to the second curing agent is (2-4):1.

[0013] Preferably, the modified epoxy resin includes a mixture of one or more of bisphenol A epoxy resin, phenolic modified epoxy resin, rubber modified epoxy resin, and polyurethane modified epoxy resin.

[0014] Preferably, the modified epoxy resin is a mixture of epoxy resin 828 and rubber resin 125 in a mixing ratio of 1:1.

[0015] Preferably, the epoxy diluent is polypropylene glycol diglycidyl ether.

[0016] Preferably, the promoter includes one of PN-23, PN-H, PN-40, PN-50, and MY-24 among the ajinomoto amine adducts.

[0017] Preferably, the coupling agent is one of UM-998, UM-B16, and KBM-403.

[0018] Preferably, the particle size of the first curing agent and the second curing agent is 5-8 μm.

[0019] In a second aspect, the present application provides a method for preparing a high-viscosity epoxy resin adhesive as described above, the preparation method comprising the following steps:

[0020] S1. Add different types of resins into a vacuum reactor in proportion, turn on the equipment for heating, raise the temperature of the epoxy resin material to between 110-120°C, turn on the stirring and vacuum equipment, adjust the speed to 35-40r / min, open the vacuum valve, stir and vacuum for 2 hours, the vacuum degree is -0.1Mpa, filter with 300 mesh, pack in resin barrels, cool and set aside, and obtain the first resin raw material;

[0021] Pour the filler silica into a conical drying kettle, adjust the temperature to 120°C, the vacuum degree to -0.1Mpa, vacuum stir and bake to remove moisture for 3 hours, seal and cool naturally for 24 hours, cool the material temperature to room temperature for standby use, and obtain the filler raw material;

[0022] S2, adding the first resin raw material into a planetary stirring kettle, opening the cooling water circulation of the stirring kettle, controlling the material temperature inside the stirring kettle at 25°C, adding the weighed epoxy diluent and defoamer into the stirring kettle under stirring, adjusting the high-speed stirrer to 1500r / min and stirring for 60 minutes;

[0023] S3. Add the composite curing agent, accelerator and filler into the stirring kettle in proportion, turn on the autorotating and orbiting stirrers, and stir and mix for 3 hours under vacuum to obtain a high-viscosity epoxy resin adhesive.

[0024] Preferably, the preparation method of the composite curing agent comprises the following steps:

[0025] A1, mixing an imidazole derivative with a thermoplastic resin, then adding a dispersant, and then dissolving the imidazole derivative in an organic solvent to obtain a first solution;

[0026] A2, dicyandiamide is mixed with a thermoplastic resin, a dispersant is subsequently added, and then dissolved in an organic solvent to obtain a second solution;

[0027] A3. Spray the first solution and the second solution into the methanol solution respectively, filter out the precipitate, and dry it to obtain the composite curing agent.

[0028] Preferably, in step A1, the mass ratio of the imidazole derivative to the thermoplastic resin is (1-10):(10-80); in step A2, the mass ratio of the dicyandiamide to the thermoplastic resin is (5-20):(20-100).

[0029] Preferably, the wall material thickness of the first curing agent and the second curing agent is 30%-60% of the ion particle diameter thereof.

[0030] Preferably, the dispersant in step A1 and step A2 is a silane dispersant.

[0031] Preferably, the organic solvent in step A1 and step A2 is chloroform.

[0032] Compared with the prior art, the beneficial effects of the present application are as follows: the core materials of dicyandiamide and imidazole derivatives selected in the present solution are released after the microcapsules are broken, and the synergistic effect of the two can significantly improve the curing efficiency and shorten the curing time; in addition, the heating temperature requirement before use is reduced, and there is no need to reach a high temperature condition of 130°C, and rapid curing can be achieved at only 110-120°C. The absence of a high temperature pre-reaction condition also protects the performance of the adhesive, avoiding the problem of performance degradation caused by the breakage of the resin molecular chain due to excessive temperature and excessive reaction time. DETAILED DESCRIPTION

[0033] In order to make the purpose, features and advantages of the present invention more obvious and easy to understand, the specific implementation methods of the present invention are described in detail below in conjunction with embodiments. Several embodiments of the present invention are given below. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the disclosure of the present invention more thorough and comprehensive:

[0034] The present application provides a high viscosity epoxy resin adhesive, which is made from the following raw material components:

[0035]

[0036] The composite curing agent includes a first curing agent and a second curing agent, and both the first curing agent and the second curing agent are microcapsule curing agents; the wall material of the first curing agent is a thermoplastic resin, and the core material is dicyandiamide; the wall material of the second curing agent is a thermoplastic resin, and the core material is an imidazole derivative, and the imidazole derivative includes one of 2-methylimidazole, 2-phenyl-4-methylimidazole, and benzimidazole:

[0037] In the above scheme, the inventors found that compared with the traditional single-type latent curing agent, the use of a two-component composite curing agent is more efficient in achieving the curing reaction. The core material dicyandiamide and imidazole derivatives selected in this scheme are released after the microcapsule is ruptured. The synergistic effect of the two can significantly improve the curing efficiency and shorten the curing time. In addition, the heating temperature requirement before use is reduced, and there is no need to reach a high temperature condition of 130°C. Rapid curing can be achieved at only 110-120°C. The absence of a high temperature pre-reaction condition also protects the performance of the adhesive and avoids the problem of performance degradation caused by the breakage of the resin molecular chain due to excessively high temperature and excessively long reaction time.

[0038] In one embodiment, the thermoplastic resin includes one of polycarbonate, polyamide, polypropylene, and polyvinyl chloride;

[0039] In the above scheme, the thermoplastic resin selected in this scheme has a relatively suitable wall breaking temperature, and under the premise of ensuring storage stability, there is no need for a too high curing reaction temperature requirement.

[0040] In one embodiment, the particle size of the first curing agent and the second curing agent is 5-8 μm;

[0041] In the above scheme, the present scheme controls the particle size of the microcapsules of the first curing agent and the second curing agent to 5-8 μm, which can ensure the stable performance of their performance; when the particle size is too large, the inventors found that the embedding rate of the microcapsules is reduced, and part of the core material cannot be effectively embedded visually, thereby affecting the subsequent storage performance; when the particle size is too small, the microcapsules are prone to association, and the dispersibility of the microcapsules becomes poor, affecting the subsequent curing reaction; in addition, too small a particle size makes the control of the reaction conditions more demanding, which invisibly increases the cost.

[0042] In one embodiment, the ratio of the first curing agent to the second curing agent is (2-4):1;

[0043] In the above scheme, the core material of the first curing agent is dicyandiamide, and the core material of the second curing agent is an imidazole derivative; the two need to be in a certain ratio to exert better curing performance; when the proportion of dicyandiamide is too high, due to the high curing temperature of dicyandiamide, it will cause the pre-heating temperature response of the adhesive to increase, and ultimately cause the adhesive to require a higher heating temperature when used, which is easy to cause the resin molecular bonds to break under high temperature conditions, and ultimately affect the mechanical properties of the resin; when the proportion of imidazole derivatives is too high, it will directly affect the mechanical properties of the resin; in addition, in some application scenarios where light transmittance needs to be considered, too many imidazole derivatives will reduce the transparency and gloss of the resin.

[0044] In one embodiment, the modified epoxy resin includes a mixture of one or more of bisphenol A epoxy resin, phenolic modified epoxy resin, rubber modified epoxy resin, and polyurethane modified epoxy resin.

[0045] Furthermore, the modified epoxy resin is mixed with epoxy resin 828 and rubber resin 125, and the mixing ratio is 1:1. The inventors found in experiments that when the resin mixture formed by mixing epoxy resin 828 and rubber resin 125 is used to produce adhesives, the final adhesive has better adhesion to PET and LCP materials than other combinations.

[0046] In one embodiment, the epoxy diluent is polypropylene glycol diglycidyl ether;

[0047] In the above scheme, this scheme uses polypropylene glycol diglycidyl ether, which can significantly improve the impact strength and thermal shock resistance of the final resin adhesive, effectively improve the problem of easy cracking of the cured product after curing, and at the same time, it has a high boiling point and is not easy to volatilize, and can be fully added to the reaction within a certain temperature range.

[0048] In one embodiment, the enhancer includes one of PN-23, PN-H, PN-40, PN-50, and MY-24 among the ajinomoto amine adducts.

[0049] In one embodiment, the coupling agent is one of UM-998, UM-B16, and KBM-403.

[0050] Furthermore, the coupling agent is preferably UM-998.

[0051] The present application also provides a method for preparing a high-viscosity epoxy resin adhesive as described above, the method comprising the following steps:

[0052] S1. Add different types of resins into a vacuum reactor in proportion, turn on the equipment for heating, raise the temperature of the epoxy resin material to between 110-120°C, turn on the stirring and vacuum equipment, adjust the speed to 35-40r / min, open the vacuum valve, stir and vacuum for 2 hours, the vacuum degree is -0.1Mpa, filter with 300 mesh, pack in resin barrels, cool and set aside, and obtain the first resin raw material;

[0053] In the above scheme, this scheme pre-treats the mixture of different types of resins. The inventors found that after pre-treatment, the crystallization phenomenon of epoxy resin during low-temperature storage can be effectively solved, and the small molecular impurities remaining in the resin production process can be effectively removed.

[0054] Pour the filler silica into a conical drying kettle, adjust the temperature to 120°C, vacuum degree to -0.1Mpa, vacuum stir and bake to remove moisture for 3 hours, seal and cool naturally for 24 hours, cool the material temperature to room temperature for standby use, and obtain the filler raw material;

[0055] In the above scheme, the silicon dioxide is pretreated and fully pretreated. By fully baking and removing moisture, the water content of the silicon dioxide can be effectively controlled, thereby reducing the effect of moisture on the viscosity of the adhesive and improving its bonding strength to PET and LCP materials.

[0056] S2, add the first resin raw material into the planetary stirring kettle, open the cooling water circulation of the stirring kettle, control the material temperature inside the stirring kettle at 25°C, add the weighed epoxy diluent and defoamer into the stirring kettle under stirring, adjust the high-speed stirrer to 1500r / min and stir for 60 minutes;

[0057] S3. Add the composite curing agent, accelerator and filler into the stirring kettle in proportion, turn on the autorotating and revolving stirrers, and stir and mix for 3 hours under vacuum to obtain the high-viscosity epoxy resin adhesive.

[0058] Furthermore, the preparation method of the composite curing agent comprises the following steps:

[0059] A1, mixing an imidazole derivative with a thermoplastic resin, then adding a dispersant, and then dissolving the imidazole derivative in an organic solvent to obtain a first solution;

[0060] A2, dicyandiamide is mixed with a thermoplastic resin, a dispersant is subsequently added, and then dissolved in an organic solvent to obtain a second solution;

[0061] A3. Spray the first solution and the second solution into the methanol solution respectively, filter out the precipitate, and dry it to obtain the composite curing agent.

[0062] In one embodiment, in step A1, the mass ratio of the imidazole derivative to the thermoplastic resin is (1-10): (10-80); in step A2, the mass ratio of the dicyandiamide to the thermoplastic resin is (5-20): (20-100).

[0063] In one embodiment, the wall material thickness of the first curing agent and the second curing agent is 30%-60% of the ion particle size thereof;

[0064] In the above scheme, when the thickness of the curing agent wall material is too large, the subsequent wall breaking will be hindered, resulting in the core material not being able to precipitate in time, affecting the curing efficiency; when the thickness of the curing agent wall material is too thin, it will affect the storage performance of the resin adhesive.

[0065] In one embodiment, the dispersant in step A1 and step A2 is a silane dispersant.

[0066] In one embodiment, the organic solvent in step A1 and step A2 is chloroform.

[0067] The technical solutions provided by the present invention are described in detail below in conjunction with the embodiments, but they should not be construed as limiting the protection scope of the present invention.

[0068] In the following embodiments, unless otherwise specified, all of them are conventional methods.

[0069] Unless otherwise specified, the materials and reagents used in the following examples can be obtained from commercial sources.

[0070] Examples 1-5

[0071] This embodiment provides a high-viscosity epoxy resin adhesive and a preparation method thereof; the method comprises the following steps:

[0072] S1. Put epoxy resin 828 into a vacuum reactor, turn on the heating equipment, raise the temperature of the epoxy resin material to between 110-120°C, turn on the stirring and vacuum equipment, adjust the speed to 35-40r / min, open the vacuum valve, stir and vacuum for 2 hours, the vacuum degree is -0.1Mpa, filter with 300 mesh, pack in resin barrels, cool and standby, and obtain the first resin raw material;

[0073] Pour the filler silica into a conical drying kettle, adjust the temperature to 120°C, the vacuum degree to -0.1Mpa, vacuum stir and bake to remove moisture for 3 hours, seal and cool naturally for 24 hours, cool the material temperature to room temperature for standby use, and obtain the filler raw material;

[0074] S2, adding the first resin raw material into a planetary stirring kettle, opening the cooling water circulation of the stirring kettle, controlling the material temperature inside the stirring kettle at 25°C, adding the weighed epoxy diluent and defoamer into the stirring kettle under stirring, adjusting the high-speed stirrer to 1500r / min and stirring for 60 minutes;

[0075] S3. Add the single-component curing agent, accelerator and filler into the stirring kettle in proportion, turn on the autorotating and revolving stirrers, and stir and mix for 3 hours under vacuum to obtain a high-viscosity epoxy resin adhesive.

[0076] The above-mentioned one-component curing agent is DICY.

[0077] The specific proportions of each component are shown in Table 1 below:

[0078] Table 1

[0079]

[0080] The adhesives produced in Examples 1-5 were tested, and the specific test results are shown in Table 2 below:

[0081] Table 2

[0082]

[0083] Referring to the above Table 1, the detection effects of each item in Example 4 are relatively balanced, so further adjustments are made based on Example 4, and the single epoxy resin 828 is replaced with a mixture of different resins. For specific results, please refer to Examples 6-10.

[0084] Embodiment 6-10

[0085] The preparation method in this embodiment can refer to Examples 1-5, wherein the selection of epoxy resin is different, and the specific ratio can be seen in Table 3;

[0086] Table 3

[0087]

[0088] Some performance tests were conducted on the above-mentioned Examples 6-10, and the bonding strengths to some specific materials were also tested. The test results can be seen in Tables 4 and 5:

[0089] Table 4

[0090]

[0091] Table 4 Adhesion strength of different plastic materials produced by glue test adhesive (N / cm 2 ), curing conditions 120℃ / 2h

[0092] serial number Example 6 Example 7 Example 8 Example 9 Example 10 PA 76.4 78.3 75.7 83.8 83.1 PBT 86.5 89.6 83.8 84.1 85.4 PET 28.7 23.3 24.6 42.5 43.6 LCP 43.1 47.4 48.7 53.6 61.4

[0093] Referring to Table 3 and Table 4, the comprehensive performances of Examples 9 and 10 are better, and the bonding force of Example 10 to PET can reach 43.6 N / cm 2 , further experiments were conducted based on implementation 10.

[0094] Examples 11-16

[0095] The preparation method in this embodiment can refer to Examples 1-5, the component contents can refer to Example 10, and the specific ratios can refer to Table 5;

[0096] Table 5

[0097]

[0098] The adhesives produced in Example 11 and Example 16 were tested, and the specific results are shown in Table 6:

[0099] Table 6 Adhesion strength of different plastic materials in the experimental adhesive (N / cm 2 ), curing conditions 120℃ / 2h

[0100]

[0101] Among them, Example 12 has higher bonding strength to PET and LCP, so further testing was carried out based on Example 12.

[0102] Embodiment 13

[0103] The preparation method of this embodiment is the same as that of embodiments 1-5, wherein the difference is that this embodiment is based on embodiment 12, and a composite curing agent is used. The preparation method of the composite curing agent comprises the following steps:

[0104] A1, mixing an imidazole derivative and a thermoplastic resin in a mass ratio of 1:50, then adding a silane dispersant, and then dissolving them in chloroform to obtain a first solution;

[0105] A2, dicyandiamide and thermoplastic resin are mixed in a mass ratio of 1:6, and then a silane dispersant is added, and then dissolved in chloroform to obtain a second solution;

[0106] A3. Spray the first solution and the second solution into the methanol solution respectively, filter out the precipitate, and dry it to obtain the composite curing agent.

[0107] Embodiment 14

[0108] The preparation method of this embodiment is the same as that of embodiments 1-5, wherein the difference is that this embodiment is based on embodiment 13, and only the first curing agent is used as the curing agent.

[0109] Embodiment 15

[0110] The preparation method of this embodiment is the same as that of embodiments 1-5, wherein the difference is that this embodiment is based on embodiment 13, and only the second curing agent is used as the curing agent.

[0111] Further tests were performed on Examples 13-15, and the specific results are shown in Table 7:

[0112] Table 7 Adhesion strength of different plastic materials in the experimental adhesive (N / cm 2 ), curing conditions 120℃ / 2h

[0113]

[0114]

[0115] Furthermore, the gel time at 125°C was tested for Examples 13-15, which were 2'12", 3'32", and 3'28", respectively. This shows that the adhesive produced by using the composite curing agent in Example 13 has lower requirements on gel temperature and gel time, and has higher gel efficiency.

[0116] The above description is only a preferred embodiment of the present application and does not constitute any form of limitation to the present application. Any simple modification, equivalent changes and modifications made to the above embodiments based on the technical essence of the present application are within the scope of the technical solution of the present application.

Claims

1. A high viscosity epoxy resin adhesive, characterized in that: Made from the following raw materials: The composite curing agent includes a first curing agent and a second curing agent, wherein the first curing agent and the second curing agent are both microcapsule curing agents; the wall material of the first curing agent is a thermoplastic resin, and the core material is dicyandiamide; the wall material of the second curing agent is a thermoplastic resin, and the core material is an imidazole derivative, and the imidazole derivative includes one of 2-methylimidazole, 2-phenyl-4-methylimidazole, and benzimidazole.

2. The high viscosity epoxy resin adhesive according to claim 1, characterized in that: The ratio of the first curing agent to the second curing agent is (2-4):

1.

3. The high viscosity epoxy resin adhesive according to claim 1, characterized in that: The modified epoxy resin includes a mixture of one or more of bisphenol A epoxy resin, phenolic modified epoxy resin, rubber modified epoxy resin and polyurethane modified epoxy resin.

4. The high viscosity epoxy resin adhesive according to claim 3, characterized in that: The modified epoxy resin is prepared by mixing epoxy resin 828 and rubber resin 125 in a mixing ratio of 1:

1.

5. The high viscosity epoxy resin adhesive according to claim 1, characterized in that: The epoxy diluent is polypropylene glycol diglycidyl ether.

6. The high viscosity epoxy resin adhesive according to claim 1, characterized in that: The accelerator includes one of PN-23, PN-H, PN-40, PN-50 and MY-24 among the ajinomoto amine adducts.

7. The high viscosity epoxy resin adhesive according to claim 6, characterized in that: The coupling agent is one of UM-998, UM-B16 and KBM-403.

8. The high viscosity epoxy resin adhesive according to claim 1, characterized in that: The particle size of the first curing agent and the second curing agent is 5-8 μm.

9. A method for preparing the high viscosity epoxy resin adhesive according to any one of claims 1 to 8, characterized in that: The preparation method comprises the following steps: S1. Add different types of resins into a vacuum reactor in proportion, turn on the equipment for heating, raise the temperature of the epoxy resin material to between 110-120°C, turn on the stirring and vacuum equipment, adjust the speed to 35-40r / min, open the vacuum valve, stir and vacuum for 2 hours, the vacuum degree is -0.1Mpa, filter with 300 mesh, pack in resin barrels, cool and set aside, and obtain the first resin raw material; Pour the filler silica into a conical drying kettle, adjust the temperature to 120°C, the vacuum degree to -0.1Mpa, vacuum stir and bake to remove moisture for 3 hours, seal and cool naturally for 24 hours, cool the material temperature to room temperature for standby use, and obtain the filler raw material; S2, adding the first resin raw material into a planetary stirring kettle, opening the cooling water circulation of the stirring kettle, controlling the material temperature inside the stirring kettle at 25°C, adding the weighed epoxy diluent and defoamer into the stirring kettle under stirring, adjusting the high-speed stirrer to 1500r / min and stirring for 60 minutes; S3. Add the composite curing agent, accelerator and filler into the stirring kettle in proportion, turn on the autorotating and revolving stirrers, and stir and mix for 3 hours under vacuum to obtain the high-viscosity epoxy resin adhesive.

10. The method for preparing a high viscosity epoxy resin adhesive according to claim 9, characterized in that: The preparation method of the composite curing agent comprises the following steps: A1, mixing an imidazole derivative with a thermoplastic resin, then adding a dispersant, and then dissolving the imidazole derivative in an organic solvent to obtain a first solution; A2, dicyandiamide is mixed with a thermoplastic resin, a dispersant is subsequently added, and then dissolved in an organic solvent to obtain a second solution; A3. Spray the first solution and the second solution into the methanol solution respectively, filter out the precipitate, and dry it to obtain the composite curing agent.

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