A water-based epoxy resin adhesive

Abstract

The present invention discloses a water-based epoxy resin adhesive, comprising the following raw materials in parts by weight: 100 parts of water-based epoxy emulsion, 24-35 parts of polyamide water-based curing agent, 20-35 parts of terminal hydroxyl polyurethane-polyurea dispersion, 5-9 parts of polyvinyl acetal, 1-2 parts of defoamer, and 4-7 parts of silane coupling agent. The water-based epoxy resin adhesive not only has excellent adhesion, but also has good flexibility and heat resistance, and can be adapted to the bonding of various materials. In addition, the synergistic addition of terminal hydroxyl polyurethane-polyurea dispersion and polyvinyl acetal in the present invention is conducive to reducing the viscosity of the emulsion under low shear, thereby unexpectedly improving the leveling performance of the adhesive.

Description

Technical Field

[0001] The invention relates to an adhesive, in particular to a water-based epoxy resin adhesive. Background Art

[0002] Epoxy resin adhesives can be used in aerospace, electronics, electrical appliances, construction, furniture, automobiles and other fields due to their good bonding strength. Their advantages also include low shrinkage, good dimensional stability and medium resistance, and easy availability of raw materials. However, epoxy resin adhesives also have some disadvantages, such as high benzene ring content, low molecular chain flexibility, high brittleness and poor heat resistance.

[0003] The prior art adopts many schemes to obtain toughened epoxy resin adhesives. For example, patents CN107325773A and CN112143426A improve toughness by adding toughening agents to the adhesive. The toughening agents are multi-functional linear macromolecules, which increase the viscosity of the adhesive. During use, the leveling property is inevitably poor, and after construction, pitting occurs, the flatness of the film is poor, and the thickness of the film is uneven, thereby affecting the overall bonding effect.

[0004] The prior art also uses many technologies to obtain epoxy resin adhesives with good leveling properties. For example, in the epoxy potting adhesive involved in CN114525100A, the inorganic filler is composed of a spherical inorganic filler treated with a coupling agent and a modified flaky inorganic filler. By size grading and adding a certain proportion of long-chain addition-type epoxy resin, the epoxy potting adhesive of the present invention has good leveling and heat dissipation properties. However, the introduction of a large amount of fillers will inevitably lead to a decrease in its flexibility, making the adhesive prone to brittle fracture.

[0005] Therefore, how to obtain an adhesive with excellent flexibility and leveling properties at the same time is a technical difficulty in this field. Summary of the invention

[0006] In order to solve the above technical problems, the present invention provides a water-based epoxy resin adhesive, which not only has excellent adhesion, but also has good flexibility and heat resistance, and can be adapted to the bonding of various materials. In addition, the synergistic addition of the terminal hydroxyl polyurethane-polyurea dispersion and polyvinyl acetal in the present invention is conducive to reducing the viscosity of the emulsion under low shear, thereby unexpectedly improving the leveling performance of the adhesive.

[0007] To achieve the above purpose, the technical solution adopted by the present invention is as follows:

[0008] A water-based epoxy resin adhesive comprises the following raw materials in parts by weight:

[0009] 100 parts of water-based epoxy emulsion,

[0010] 24-35 parts of polyamide water-based curing agent,

[0011] 20-35 parts of hydroxyl-terminated polyurethane-polyurea dispersion,

[0012] Polyvinyl acetal 5-9 parts,

[0013] 1-2 parts of defoaming agent,

[0014] Silane coupling agent 4-7 parts.

[0015] As a preferred embodiment, the solid content of the aqueous epoxy emulsion is 40-55%, and is selected from one or more of bisphenol A epoxy emulsion, bisphenol F epoxy emulsion, aliphatic glycidyl ether epoxy emulsion, and aliphatic glycidyl ester epoxy emulsion, preferably one or more of GS-730A, banco2060, banco2060H, banco5057, Araldite PZ3961, and WE520.

[0016] As a preferred embodiment, the polyamide water-based curing agent is prepared by reacting bisphenol A epoxy resin, polyamide, monofunctional glycidyl ether, and a salt-forming agent.

[0017] As a preferred embodiment, the bisphenol A epoxy resin is selected from one or more of E51, E44, E42, E35, and E55;

[0018] Preferably, the added amount of the polyamide is 50-65% of the mass of the bisphenol A epoxy resin; the added amount of the monofunctional glycidyl ether is 30-40% of the mass of the bisphenol A epoxy resin; and the added amount of the salt-forming agent is 7-10% of the mass of the bisphenol A epoxy resin.

[0019] As a preferred embodiment, the amine value of the polyamide is 200-400 mgKOH / g;

[0020] Preferably, the monofunctional glycidyl ether is a glycidyl ether having an alkyl carbon number of 12-18, preferably one or more of dodecyl glycidyl ether, tetradecyl glycidyl ether, hexadecyl glycidyl ether, and octadecyl glycidyl ether;

[0021] Preferably, the salt-forming agent is one or more of acetic acid, citric acid, oxalic acid, and salicylic acid;

[0022] Preferably, the preparation method of the polyamide water-based curing agent is as follows:

[0023] Bisphenol A epoxy resin and polyamide are mixed and reacted at 50-65°C for 10-30 minutes; then monofunctional glycidyl ether is added and the reaction is continued for 20-30 minutes to obtain a capped product; finally, the temperature is lowered to room temperature, a salt-forming agent is added, and the reaction is continued for 20-30 minutes to obtain a polyamide water-based curing agent.

[0024] As a preferred embodiment, the solid content of the hydroxyl-terminated polyurethane-polyurea dispersion is 30-40%;

[0025] Preferably, the preparation method of the hydroxyl-terminated polyurethane-polyurea dispersion is as follows:

[0026] Add diisocyanate to the dehydrated polyethylene glycol and react at 70-90° C. for 1-2 hours; cool to 5-10° C., slowly add ethylenediamine and react for 20-35 minutes, and finally add acetone to disperse to obtain the hydroxyl-terminated polyurethane-polyurea dispersion.

[0027] As a preferred embodiment, the addition amount of the diisocyanate is 5-20% of the mass of the polyethylene glycol; the diisocyanate is preferably an aliphatic, alicyclic, or aromatic diisocyanate, preferably one or more of isophorone diisocyanate, diphenylmethane diisocyanate, hexamethylene diisocyanate, toluene diisocyanate, and dicyclohexylmethane diisocyanate;

[0028] Preferably, the amount of ethylenediamine added is 0.15-0.45% of the mass of polyethylene glycol;

[0029] Preferably, the molecular weight of the polyethylene glycol is 1000-3000.

[0030] As a preferred embodiment, the polyvinyl acetal is polyvinyl butyral having a hydroxyl content of 28-36 mol% and a butyral content of 64-72 mol%, preferably Japan Sekisui BM-2.

[0031] As a preferred embodiment, the defoaming agent is a paraffin defoaming agent, preferably one or more of BYK024, BYK028, BYK-088, BYK-A530, and BYK054.

[0032] As a preferred embodiment, the silane coupling agent is one or more of γ-glycidyloxypropyltrimethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltriethoxysilane, and (2,3-epoxypropyloxy)propyltrimethoxysilane.

[0033] Preferably, the preparation method of the water-based epoxy resin adhesive can be:

[0034] After adding the polyamide water-based curing agent to the water-based epoxy resin emulsion, stir for 10-15 minutes, then add the terminal hydroxyl polyurethane-polyurea dispersion and polyvinyl acetal, stir for 10-15 minutes, then add the silane coupling agent, stir for 5-8 minutes, and finally add the defoamer and stir for 5-10 minutes.

[0035] The beneficial effects of the present invention are:

[0036] (1) The addition of hydroxyl-terminated polyurethane-polyurea dispersion and polyvinyl acetal not only synergistically improves the toughness and heat resistance of the adhesive, but also unexpectedly finds that the viscosity of the obtained product at low shear rate decreases significantly and exhibits good leveling properties without adding additives;

[0037] (2) The polyamide water-based curing agent is modified with monofunctional glycidyl ether and a long carbon chain is introduced to further improve the toughness of the adhesive. DETAILED DESCRIPTION

[0038] The present invention is further described below by means of specific examples. The examples described in the present invention are only used to illustrate the present invention and do not limit the scope of the present invention.

[0039] The main testing methods of the following embodiments of the present invention are as follows:

[0040] (1) Tensile shear strength

[0041] The adhesive sample was evenly coated on two aluminum sheets for bonding. The size of the aluminum sheets was 100mm×25mm×2mm, the length of the adhesive coating was 15mm, and a wire rod was used to ensure that the adhesive coating thickness was about 0.2mm. The bonded aluminum sheets were placed in an oven at 80℃ for 1h to cure and form. Subsequently, the tensile shear strength at room temperature and 210℃ was tested according to GB / T 7124-2008.

[0042] (2) Impact strength

[0043] The adhesive sample was evenly coated on two aluminum sheets for bonding. The size of the aluminum sheets was 100mm×25mm×2mm. The two bonding test pieces were accurately aligned and the adhesive coating length was 15mm. The bonded aluminum sheets were placed in an oven at 80℃ for 1 hour to cure and form. The impact strength of the aluminum sheet at room temperature was tested according to the standard GB / T 6328-1999.

[0044] (3) Heat resistance

[0045] The adhesive sample was evenly coated on two aluminum sheets for bonding. The size of the aluminum sheets was 100mm×25mm×2mm, the length of the glue coating was 15mm, and a wire rod was used to ensure that the glue coating thickness was about 0.2mm. The aluminum sheet was placed in an oven at 80°C for 1 hour to cure and form. The aluminum sheet was then hung vertically in a 90°C oven, and a 2kg weight was hung under one side of the aluminum sheet. After 1 hour, the relative slip of the two aluminum sheets was measured. The more slip, the worse the heat resistance.

[0046] (4) Viscosity

[0047] The emulsion was placed in a 25°C constant temperature water bath and allowed to equilibrate for 30 minutes. Subsequently, the viscosity of the emulsion was measured using a Brookfield viscometer with a rotor of LV 64#. The equilibration time was 3 minutes at a low shear rate of 0.1 rpm and 1 minute at a speed of 10 rpm. The value displayed by the instrument after the equilibration time is the viscosity at the corresponding speed.

[0048] [Example 1]

[0049] (1) Preparation of polyamide water-based curing agent:

[0050] 10 parts of E-51 resin and 5 parts of polyamide with an amine value of 200 mgKOH / g (polyamide 650, Changzhou Deye Chemical) were mixed and reacted at 50°C for 10 minutes; then 3 parts of dodecyl glycidyl ether were added and reacted for 20 minutes to obtain a capped product; finally, the temperature was cooled to room temperature, 1 part of acetic acid was added as a salt-forming agent, and the reaction was carried out for 10 minutes to obtain a polyamide water-based curing agent.

[0051] (2) Preparation of hydroxyl-terminated polyurethane-polyurea dispersion:

[0052] 0.5 parts of isophorone diisocyanate were added to 10 parts of polyethylene glycol with a molecular weight of 1000 (PEG-1000, Jiangsu Hai'an Petrochemical Plant), and the mixture was reacted at 80°C for 2 hours; the mixture was cooled to 10°C, 0.015 parts of ethylenediamine were slowly added and reacted for 20 minutes, and finally acetone was added to disperse the mixture to obtain a hydroxyl-terminated polyurethane-polyurea dispersion with a solid content of 30%.

[0053] (3) Preparation of adhesive:

[0054] To 100 parts of waterborne epoxy resin emulsion (Araldite PZ3961), 35 parts of polyamide waterborne curing agent were added and stirred for 12 minutes. Then, 20 parts of terminal hydroxyl polyurethane-polyurea dispersion and 5 parts of polyvinyl butyral (Japan Sekisui BM-2) were added and stirred for 10 minutes. Then, 4 parts of γ-glycidyloxypropyltrimethoxysilane were added and stirred for 6 minutes. Finally, 1 part of defoamer BYK024 was added and stirred for 10 minutes to prepare an adhesive.

[0055] [Example 2]

[0056] (1) Preparation of polyamide water-based curing agent:

[0057] 10 parts of E-44 resin and 5.5 parts of polyamide with an amine value of 300 mgKOH / g (polyamide 300, Changzhou Deye Chemical) were mixed and reacted at 60°C for 30 minutes; at this temperature, 3.3 parts of tetradecyl glycidyl ether were added and reacted for 25 minutes to obtain a capped product; finally, the temperature was lowered to room temperature, 0.9 parts of oxalic acid was added as a salt-forming agent and stirred for 10 minutes to obtain a polyamide water-based curing agent.

[0058] (2) Preparation of hydroxyl-terminated polyurethane-polyurea dispersion:

[0059] To 10 parts of polyethylene glycol with a molecular weight of 1000 (PEG-1000, Jiangsu Hai'an Petrochemical Plant), 2 parts of diphenylmethane diisocyanate were added and reacted at 70°C for 2 hours; the temperature was lowered to 8°C, 0.02 parts of ethylenediamine were slowly added and reacted for 35 minutes, and finally acetone was added for dispersion to obtain a hydroxyl-terminated polyurethane-polyurea dispersion with a solid content of 35%.

[0060] (3) Preparation of adhesive:

[0061] After adding 30 parts of polyamide water-based curing agent to 100 parts of water-based epoxy resin emulsion (GS-730A), stirring for 10 minutes, 30 parts of terminal hydroxyl polyurethane-polyurea dispersion and 7 parts of polyvinyl butyral (Japan Sekisui BM-2) were added, stirring for 12 minutes, and then 6 parts of (2,3-epoxypropoxy)propyltrimethoxysilane were added, stirring for 5 minutes, and finally 2 parts of defoaming agent BYK028 were added and stirred for 7 minutes to prepare the adhesive.

[0062] [Example 3]

[0063] (1) Preparation of polyamide water-based curing agent:

[0064] 10 parts of E-55 resin and 6.5 parts of polyamide with an amine value of 250 mgKOH / g (polyamide 650B, Changzhou Deye Chemical) were mixed and reacted at 65°C for 20 minutes; at this temperature, 3.6 parts of octadecyl glycidyl ether were added and reacted for 30 minutes to obtain a capped product; finally, the temperature was lowered to room temperature, 0.7 parts of salicylic acid was added as a salt-forming agent and stirred for 20 minutes to obtain a polyamide water-based curing agent.

[0065] (2) Preparation of hydroxyl-terminated polyurethane-polyurea dispersion:

[0066] 0.5 parts of diphenylmethane diisocyanate were added to 10 parts of polyethylene glycol with a molecular weight of 3000 (PEG-3000, Jiangsu Hai'an Petrochemical Plant) and reacted at 80°C for 1 hour; the temperature was lowered to 10°C, 0.03 parts of ethylenediamine were slowly added and reacted for 25 minutes, and finally acetone was added for dispersion to obtain a hydroxyl-terminated polyurethane-polyurea dispersion with a solid content of 40%.

[0067] (3) Preparation of adhesive:

[0068] To 100 parts of waterborne epoxy resin emulsion (banco2060H), 32 parts of polyamide waterborne curing agent were added and stirred for 11 minutes. Then, 35 parts of terminal hydroxyl polyurethane-polyurea dispersion and 6 parts of polyvinyl butyral (Japan Sekisui BM-2) were added and stirred for 10 minutes. Then, 5 parts of 2-(3,4-epoxycyclohexyl)ethyltriethoxysilane were added and stirred for 7 minutes. Finally, 1.5 parts of defoaming agent BYK-A530 were added and stirred for 9 minutes to prepare an adhesive.

[0069] [Example 4]

[0070] (1) Preparation of polyamide water-based curing agent:

[0071] 10 parts of E-42 resin and 6 parts of polyamide with an amine value of 400 mgKOH / g (polyamide 651, Changzhou Deye Chemical) were mixed and reacted at 65°C for 20 minutes; at this temperature, 4 parts of hexadecyl glycidyl ether were added and reacted for 25 minutes to obtain a capped product; finally, the temperature was lowered to room temperature, 0.8 parts of acetic acid was added as a salt-forming agent, and the reaction was stirred for 10 minutes to obtain a polyamide water-based curing agent.

[0072] (2) Preparation of hydroxyl-terminated polyurethane-polyurea dispersion:

[0073] 0.8 parts of hexamethylene diisocyanate were added to 10 parts of polyethylene glycol with a molecular weight of 1500 (PEG-1500, Jiangsu Hai'an Petrochemical Plant), and the mixture was reacted at 80°C for 1.5 hours; the mixture was cooled to 6°C, 0.045 parts of ethylenediamine were slowly added and reacted for 35 minutes, and finally acetone was added to disperse the mixture to obtain a hydroxy-terminated polyurethane-polyurea dispersion with a solid content of 38%.

[0074] (3) Preparation of adhesive:

[0075] To 100 parts of waterborne epoxy resin emulsion (WE520), 24 parts of polyamide waterborne curing agent were added, stirred for 15 minutes, and then 25 parts of terminal hydroxyl polyurethane-polyurea dispersion and 8 parts of polyvinyl butyral (Japan Sekisui BM-2) were added, stirred for 13 minutes, and then 7 parts of γ-glycidyloxypropyltrimethoxysilane were added, stirred for 8 minutes, and finally 1 part of defoaming agent BYK-088 was added, stirred for 8 minutes to prepare an adhesive.

[0076] [Example 5]

[0077] (1) Preparation of polyamide water-based curing agent:

[0078] 10 parts of E-35 resin and 5.5 parts of polyamide with an amine value of 200 mgKOH / g (polyamide 650A, Changzhou Deye Chemical) were mixed and reacted at 55°C for 30 minutes; at this temperature, 3.8 parts of dodecyl glycidyl ether were added and reacted for 30 minutes to obtain a capped product; finally, the temperature was lowered to room temperature, 0.9 parts of citric acid was added as a salt-forming agent and stirred for 20 minutes to obtain a polyamide water-based curing agent.

[0079] (2) Preparation of hydroxyl-terminated polyurethane-polyurea dispersion:

[0080] 0.9 parts of diphenylmethane diisocyanate were added to 10 parts of polyethylene glycol with a molecular weight of 2500 (PEG-2500, Jiangsu Hai'an Petrochemical Plant), and the mixture was reacted at 90°C for 2 hours; the mixture was cooled to 5°C, 0.04 parts of ethylenediamine were slowly added and reacted for 20 minutes, and finally acetone was added to disperse the mixture to obtain a hydroxyl-terminated polyurethane-polyurea dispersion with a solid content of 30%.

[0081] (3) Preparation of adhesive:

[0082] After adding 28 parts of polyamide water-based curing agent to 100 parts of water-based epoxy resin emulsion (banco5057), stirring for 13 minutes, 20 parts of terminal hydroxyl polyurethane-polyurea dispersion and 9 parts of polyvinyl butyral (Japan Sekisui BM-2) were added, stirring for 15 minutes, and then 6 parts of (2,3-epoxypropoxy)propyltrimethoxysilane were added, stirring for 6 minutes, and finally 2 parts of defoaming agent BYK054 were added and stirred for 5 minutes to prepare an adhesive.

[0083] [Comparative Example 1]

[0084] The adhesive was prepared by referring to the method basically the same as that in Example 1, except that the hydroxyl-terminated polyurethane-polyurea dispersion was not added.

[0085] [Comparative Example 2]

[0086] The adhesive was prepared by referring to the method substantially the same as that in Example 1, except that the hydroxyl-terminated polyurethane-polyurea dispersion was replaced by a hydroxyl-terminated polyurethane dispersion prepared by the following method:

[0087] 0.5 parts of isophorone diisocyanate were added to 10 parts of polyethylene glycol with a molecular weight of 1000, and the mixture was reacted at 80°C for 2 hours; the mixture was cooled to 10°C, and acetone was added to disperse the mixture, thereby obtaining a hydroxyl-terminated polyurethane dispersion with a solid content of 30%.

[0088] [Comparative Example 3]

[0089] The adhesive was prepared by referring to the method basically the same as Example 1, except that no polyvinyl butyral was added.

[0090] [Comparative Example 4]

[0091] The adhesive was prepared by referring to the method basically the same as that in Example 1, except that the hydroxyl-terminated polyurethane-polyurea dispersion and polyvinyl butyral were not added at the same time.

[0092] [Comparative Example 5]

[0093] The adhesive was prepared by referring to the method basically the same as Example 1, except that the amount of polyvinyl butyral added was changed to 15 parts.

[0094] [Comparative Example 6]

[0095] The adhesive was prepared by referring to the method basically the same as that in Example 1, except that in step (1), when preparing the polyamide water-based curing agent, dodecyl glycidyl ether was not added.

[0096] The adhesives provided in each embodiment and comparative example were subjected to the performance tests shown in Table 1, and the test results are as follows:

[0097] Table 1. Adhesive performance test

[0098]

[0099]

[0100] The above is only a preferred embodiment of the present invention. It should be pointed out that ordinary technicians in this field can make several improvements and supplements without departing from the method of the present invention. These improvements and supplements should also be regarded as the scope of protection of the present invention.

Claims

1. A water-based epoxy resin adhesive, characterized in that: Contains the following raw materials in parts by weight: 100 parts of water-based epoxy emulsion, 24-35 parts of polyamide water-based curing agent, 20-35 parts of hydroxyl-terminated polyurethane-polyurea dispersion, Polyvinyl acetal 5-9 parts, 1-2 parts of defoaming agent, Silane coupling agent 4-7 parts; The polyamide water-based curing agent is prepared by reacting bisphenol A epoxy resin, polyamide, monofunctional glycidyl ether and a salt-forming agent.

2. The water-based epoxy resin adhesive according to claim 1, characterized in that: The solid content of the waterborne epoxy emulsion is 40-55%, and the waterborne epoxy emulsion is selected from one or more of bisphenol A epoxy emulsion, bisphenol F epoxy emulsion, aliphatic glycidyl ether epoxy emulsion, and aliphatic glycidyl ester epoxy emulsion.

3. The water-based epoxy resin adhesive according to claim 2, characterized in that: The water-based epoxy emulsion is selected from one or more of GS-730A, banco2060, banco2060H, banco5057, Araldite PZ3961, and WE520.

4. The water-based epoxy resin adhesive according to claim 1, characterized in that: The bisphenol A type epoxy resin is selected from one or more of E51, E44, E42, E35, and E55.

5. The water-based epoxy resin adhesive according to claim 4, characterized in that: The added amount of the polyamide is 50-65% of the mass of the bisphenol A epoxy resin; the added amount of the monofunctional glycidyl ether is 30-40% of the mass of the bisphenol A epoxy resin; and the added amount of the salt-forming agent is 7-10% of the mass of the bisphenol A epoxy resin.

6. The water-based epoxy resin adhesive according to claim 4, characterized in that: The amine value of the polyamide is 200-400 mgKOH / g.

7. The water-based epoxy resin adhesive according to claim 6, characterized in that: The monofunctional glycidyl ether is a glycidyl ether having an alkyl group with 12 to 18 carbon atoms.

8. The water-based epoxy resin adhesive according to claim 7, characterized in that: The monofunctional glycidyl ether is one or more of dodecyl glycidyl ether, tetradecyl glycidyl ether, hexadecyl glycidyl ether, and octadecyl glycidyl ether.

9. The water-based epoxy resin adhesive according to claim 7, characterized in that: The salt-forming agent is one or more of acetic acid, citric acid, oxalic acid and salicylic acid.

10. The water-based epoxy resin adhesive according to any one of claims 1 to 9, characterized in that: The solid content of the hydroxyl-terminated polyurethane-polyurea dispersion is 30-40%.

11. The water-based epoxy resin adhesive according to claim 10, characterized in that: The preparation method of the hydroxyl-terminated polyurethane-polyurea dispersion is as follows: Add diisocyanate to the dehydrated polyethylene glycol and react at 70-90° C. for 1-2 hours; cool to 5-10° C., slowly add ethylenediamine and react for 20-35 minutes, and finally add acetone to disperse to obtain the hydroxyl-terminated polyurethane-polyurea dispersion.

12. The water-based epoxy resin adhesive according to claim 11, characterized in that: The added amount of the diisocyanate is 5-20% of the mass of the polyethylene glycol.

13. The water-based epoxy resin adhesive according to claim 12, characterized in that: The diisocyanate is an aliphatic, alicyclic or aromatic diisocyanate.

14. The water-based epoxy resin adhesive according to claim 13, characterized in that: The diisocyanate is one or more of isophorone diisocyanate, diphenylmethane diisocyanate, hexamethylene diisocyanate, toluene diisocyanate, and dicyclohexylmethane diisocyanate.

15. The water-based epoxy resin adhesive according to claim 12, characterized in that: The added amount of ethylenediamine is 0.15-0.45% of the mass of polyethylene glycol.

16. The water-based epoxy resin adhesive according to claim 15, characterized in that: The molecular weight of the polyethylene glycol is 1000-3000.

17. The water-based epoxy resin adhesive according to claim 1, characterized in that: The polyvinyl acetal is polyvinyl butyral with a hydroxyl content of 28-36 mol% and a butyral content of 64-72 mol%.

18. The water-based epoxy resin adhesive according to claim 17, characterized in that: The polyvinyl acetal is Japan Sekisui BM-2.

19. The water-based epoxy resin adhesive according to claim 1, characterized in that: The defoaming agent is a paraffin defoaming agent.

20. The water-based epoxy resin adhesive according to claim 19, characterized in that: The defoaming agent is one or more of BYK024, BYK028, BYK-088, BYK-A530, and BYK054.

21. The water-based epoxy resin adhesive according to claim 1, characterized in that: The silane coupling agent is one or more of γ-glycidyloxypropyltrimethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltriethoxysilane, and (2,3-epoxypropyloxy)propyltrimethoxysilane.

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