Modified polyacrylamide curing agent for epoxy resin as well as preparation method and application of modified polyacrylamide curing agent

Abstract

The invention belongs to the technical field of adhesives with high adhesive strength, and particularly relates to a modified polyacrylamide curing agent for epoxy resin as well as a preparation method and application of the modified polyacrylamide curing agent. The curing agent contains an amide group and a silica group, and the preparation method of the curing agent comprises the following steps: (1) adding an acrylamide monomer into a solvent, heating until the temperature does not exceed 50 DEG C, adjusting the stirring rotating speed to 500-1000rpm until uniform stirring, simultaneously dropwise adding a mixed solution of an initiator and the solvent, and reacting for 15-60 minutes; and (2) adding ammonia water to adjust the pH value to 8-10, then dropwise adding a mixed solution of a hydrolysis inhibitor and acryloyloxy oxysilane, reacting for 2-6 hours, and then cooling to room temperature to obtain a sticky product. The curing agent contains siloxy groups capable of being hydrolyzed into silanol, a compact silane layer can be formed on the surface of an inorganic material, the interface bonding force and mechanical strength are greatly improved, and meanwhile the curing agent contains amino groups capable of being combined with epoxy resin to form a three-dimensional network structure.

Description

Technical Field

[0001] The invention belongs to the technical field of high-strength adhesives, and specifically relates to a modified polyacrylamide curing agent for epoxy resin, a preparation method and an application thereof. Background Art

[0002] As a thermosetting plastic with excellent comprehensive performance, epoxy resin has the characteristics of high bonding strength, low shrinkage and excellent mechanical properties after adding curing agent to form a three-dimensional cross-linked network structure. It is widely used in many fields such as coatings, adhesives, factories, construction, and aerospace. However, the interfacial bonding ability of epoxy resin adhesives is uneven, among which the bonding force of water-based epoxy resin is significantly weaker than that of oil-based epoxy resin. With the continuous improvement of the interfacial bonding strength requirements in the fields of electronic devices, metals, anti-corrosion coatings, and concrete surface repair and protection, it can no longer meet the needs of development. The interfacial bonding force has become a barrier affecting the development of epoxy resin.

[0003] As an important component of epoxy resin adhesives, curing agents are divided into multiple categories according to their chemical composition and uses. Common room temperature curing curing agents include aliphatic amines, alicyclic amines, aromatic amines, and acid anhydrides. At present, only a certain type of epoxy resin can be synthesized to match it. Therefore, each new curing agent developed can solve one aspect of the problem, which is equivalent to developing a new epoxy resin or opening up a new use for epoxy resin. It can be seen that the development of new curing agents is of great significance. Patent CN 102702484 A discloses an epoxy resin modified water-based polyacrylamide as a curing agent for epoxy emulsion, which improves the compatibility and stability with epoxy emulsion, and improves the acid and alkali resistance and corrosion resistance of the paint film.

[0004] The interface between polymer and inorganic filler involves many complex physical and chemical interactions, which are closely related to the bonding strength and mechanical strength of the materials. The important destructive factor affecting the interfacial bonding strength is the migration of water to the hydrophilic surface of the inorganic material, which destroys the interfacial bonding ability. Therefore, it is very important to develop a curing agent that can improve the interfacial bonding strength of epoxy resin. Summary of the invention

[0005] In view of the problems in the prior art, the present invention discloses a modified polyacrylamide curing agent for epoxy resin and a preparation method thereof.

[0006] In order to achieve the above-mentioned purpose of the present invention, the following technical solutions are particularly adopted:

[0007] The first aspect of the present invention provides a modified polyacrylamide curing agent for epoxy resin, the structural formula of which is:

[0008]

[0009] wherein n is 20 to 200; R is methyl, ethyl or trimethylsiloxane;

[0010] The number average molecular weight of the modified polyacrylamide curing agent is 10 4 ~10 5 .

[0011] The second aspect of the present invention provides a method for preparing the modified polyacrylamide curing agent for epoxy resin according to the first aspect, comprising the following steps:

[0012] (1) Add acrylamide monomer to solvent, raise the temperature to no more than 50° C., adjust the stirring speed to 500-1000 rpm until the mixture is uniformly stirred, and simultaneously dropwise add a mixture of initiator and solvent, and react for 15-60 minutes;

[0013] (2) Ammonia water is added to adjust the pH to 8-10, and then a mixture of a hydrolysis inhibitor and an acryloxy silane is added dropwise, and the reaction is continued for 2-6 hours, and then the temperature is lowered to room temperature to obtain a viscous product.

[0014]

[0015] Preferably, the acryloxy silane in step (2) is 3-methacryloxypropyltrimethoxysilane, 3-acryloxypropyltrimethoxysilane, 3-methacryloxypropyltriethoxysilane, or 3-methacryloxypropyltris(trimethylsiloxysilyl)silane, and the amount of the acryloxy silane used is 10wt% to 60wt% of acrylamide.

[0016] Preferably, the hydrolysis inhibitor in step (2) is ethylene glycol, and the amount used is 6wt% to 15wt% of acrylamide.

[0017] Preferably, the solvent in step (1) is acetone, the amount of the solvent added to the acrylamide monomer is 10 to 15 times the mass of acrylamide, and the amount of the solvent mixed with the initiator is 1 to 5 times the mass of acrylamide.

[0018] Preferably, the initiator in step (1) is azobisisoheptanonitrile, and the amount used is 0.5wt% to 1wt% of acrylamide; the amount of ammonia water used is 0.5wt% to 1.5wt% of acrylamide.

[0019] Preferably, the droplet speed of the mixed solution of the initiator and the solvent in step (1) is 15 to 65 drops / min.

[0020] Preferably, the droplet acceleration of the mixed solution of the hydrolysis inhibitor and the acryloxy silane in step (2) is 10 to 60 drops / min.

[0021] The third aspect of the present invention provides an epoxy resin adhesive, which is mainly made of the following raw materials in parts by weight: 100 parts of component A, 60 to 80 parts of component B;

[0022] The component A is composed of 100 parts of epoxy resin, 3 to 20 parts of diluent and 3 to 30 parts of mixed filler;

[0023] The component B is composed of 30 to 60 parts of the modified polyacrylamide curing agent described in the first aspect, 5 to 25 parts of a diluent, 3 to 15 parts of an accelerator, and 3 to 20 parts of a mixed filler.

[0024] Preferably, the epoxy resin is bisphenol A epoxy resin or bisphenol F epoxy resin;

[0025] More preferably, the bisphenol A epoxy resin is one of E51, E44 and E35, and the bisphenol F epoxy resin is F44 or F51.

[0026] Preferably, the A component diluent is one of allyl glycidyl ether, n-butyl glycidyl ether, phenyl glycidyl ether, acetone, ethanol, benzyl alcohol, dibutyl phthalate, and xylene.

[0027] Preferably, the B component diluent is one of ethanol, acetone, xylene, benzyl alcohol, and dibutyl phthalate.

[0028] Preferably, the mixed filler is at least one of silicon micropowder, quartz sand, alumina powder, glass fiber, carbon fiber, titanium dioxide, calcium powder, fumed silica, mica powder, bentonite, silica fume, talc, nano-silicon dioxide, and nano-calcium.

[0029] Preferably, the accelerator is one of 2,4,6-tris(dimethylaminomethyl)phenol, triethylamine, triethanolamine, benzyldimethylamine, 2-ethyl-4-methylimidazole and thiourea.

[0030] The fourth aspect of the present invention provides a method for preparing the epoxy resin adhesive described in the third aspect, specifically: mixing component A and grinding it for 60 to 120 minutes, mixing component B and stirring it for 60 to 120 minutes, then mixing component A and component B by weight and grinding them for 10 to 30 minutes to obtain the epoxy resin adhesive.

[0031] Compared with the prior art, the present invention has the following beneficial effects:

[0032] (1) The modified polyacrylamide curing agent for epoxy resin of the present invention contains silanol groups that can be hydrolyzed into silanols. The silanols react with metal hydroxyl groups on the surface of inorganic materials to form silanol structures and remove water, thereby forming a dense silane layer on the surface of the inorganic material, making the surface of the inorganic material further away from the interface, reducing the local stress between the interfaces, increasing the wettability and strength of the inorganic material surface, and greatly improving the interfacial adhesion and moisture resistance with the inorganic material surface; at the same time, it contains amino groups that can combine with epoxy resin to form a three-dimensional network structure.

[0033] (2) The present invention uses acryloxy silane-modified polyacrylamide as a curing agent for epoxy resin. The acryloxy silane contains unsaturated carbon-carbon double bonds, which are linked to the polyacrylamide in a chemically bonded manner, thereby improving the stability and mechanical strength of the epoxy matrix.

[0034] (3) The steel-to-steel shear strength of the adhesive prepared by the modified polyacrylamide curing agent of the present invention is 23.6-24.0 MPa, and the impact strength is 15.5-16.4 KJ / m 2 The positive tensile bonding strength of steel to dry concrete (C45) is 10.8~11.9MPa and it is cohesive failure of concrete. The positive tensile bonding strength of steel to dry concrete (C45) is 2.8~11.9MPa. The positive tensile bonding strength of steel to wet concrete (C45) is 10.5~10.8MPa. The shrinkage rate is 0.04%~0.08%, and the compressive strength is 106.2MPa~111.0MPa. DETAILED DESCRIPTION

[0035] The method of the present invention is described in detail below with reference to specific examples.

[0036] Example 1

[0037] A method for preparing a modified polyacrylamide curing agent for epoxy resin comprises the following steps:

[0038] (1) 30.5 g of acrylamide monomer was added to a three-necked flask with a stirring device and a condenser, and then added to 305 g of acetone solvent. After completion, the temperature was raised, the water bath temperature was adjusted to 50° C., and the stirring speed was adjusted to 600 rpm until the stirring was uniform. At the same time, 0.16 g of azobisisoheptanenitrile and 60.5 g of acetone were mixed and placed in a constant pressure dropping funnel. The mixture was added dropwise to the three-necked flask at a rate of 20 drops / min using the constant pressure dropping funnel, and the reaction was continued for 15 min.

[0039] (2) 0.18 g of ammonia water was added to adjust the pH to 8, and then 1.83 g of ethylene glycol and 3.05 g of 3-methacryloxypropyltrimethoxysilane were mixed evenly, and added dropwise to the three-necked flask at a rate of 15 drops / min using a constant pressure dropping funnel, and the reaction was continued for 5 h, and then the temperature was lowered to obtain a viscous product. Its structure is shown in Formula 1.

[0040] A preparation method of an epoxy resin adhesive comprises the following steps:

[0041] (1) In a 1L grinding jar, 100 g of E51 epoxy resin, 8 g of n-butyl glycidyl ether, 5 g of alumina powder, 5 g of calcium powder, 2 g of glass fiber, and 2 g of fumed silica were added in sequence, placed in a grinder, and ground for 60 min to obtain component A;

[0042] (2) Weigh 60 g of modified curing agent, 25 g of acetone, 3 g of 2,4,6-tris(dimethylaminomethyl)phenol, 15 g of alumina powder, 3 g of calcium powder, 1 g of glass fiber and 1 g of fumed silica, put them into a disperser and stir for 60 min to obtain component B;

[0043] (3) Weigh 100 g of component A and 60 g of component B respectively, mix them, and grind them for 30 minutes to prepare an epoxy resin adhesive.

[0044] Example 2

[0045] A method for preparing a modified polyacrylamide curing agent for epoxy resin comprises the following steps:

[0046] (1) 30.5 g of acrylamide monomer was added to a three-necked flask with a stirring device and a condenser, and then 350 g of acetone solvent was added. After completion, the temperature was raised, the water bath temperature was adjusted to 50° C., and the stirring speed was adjusted to 900 rpm until the stirring was uniform. At the same time, 0.25 g of azobisisoheptanenitrile and 94.5 g of acetone were mixed and placed in a constant pressure dropping funnel. The mixture was added dropwise to the three-necked flask at a rate of 55 drops / min using the constant pressure dropping funnel, and the reaction was continued for 15 min.

[0047] (2) 0.22 g of ammonia water was added to adjust the pH to 10, and then 4.5 g of ethylene glycol and 18 g of 3-methacryloxypropyltriethoxysilane were mixed evenly and added dropwise to the three-necked flask at a rate of 45 drops / min using a constant pressure dropping funnel. The reaction was continued for 3 h, and then the temperature was lowered to obtain a viscous product.

[0048] A preparation method of an epoxy resin adhesive comprises the following steps:

[0049] (1) In a 1L grinding jar, 100 g of E51 epoxy resin, 10 g of phenyl glycidyl ether, 20 g of silicon powder, 3 g of titanium dioxide, 5 g of mica powder, and 2 g of fumed silica were added in sequence, placed in a grinder, and ground for 60 min to obtain component A;

[0050] (2) Weigh 50 g of modified curing agent, 5 g of benzyl alcohol, 10 g of 2-ethyl-4-methylimidazole, 5 g of silica powder, 2 g of titanium dioxide and 3 g of mica powder respectively, put them into a disperser and stir for 60 min to obtain component B;

[0051] (3) Weigh 100 g of component A and 70 g of component B respectively, mix them, and grind them for 30 minutes to prepare an epoxy resin adhesive.

[0052] Example 3

[0053] A method for preparing a modified polyacrylamide curing agent for epoxy resin comprises the following steps:

[0054] (1) 30.5 g of acrylamide monomer was added to a three-necked flask with a stirring device and a condenser, and then added to 400 g of acetone solvent. After completion, the temperature was raised, the water bath temperature was adjusted to 50° C., and the stirring speed was adjusted to 850 rpm until the stirring was uniform. At the same time, 0.3 g of azobisisoheptanenitrile and 40 g of acetone were mixed and placed in a constant pressure dropping funnel. The mixture was added dropwise to the three-necked flask at a rate of 55 drops / min using the constant pressure dropping funnel, and the reaction was continued for 15 min.

[0055] (2) 0.18 g of ammonia water was added to adjust the pH to 8, and then 3.7 g of ethylene glycol and 12.5 g of 3-acryloxypropyltrimethoxysilane were mixed evenly and added dropwise to the three-necked flask at a rate of 40 drops / min using a constant pressure dropping funnel. The reaction was continued for 3.5 h, and then the temperature was lowered to obtain a viscous product.

[0056] A preparation method of an epoxy resin adhesive comprises the following steps:

[0057] (1) In a 1L grinding jar, 100 g F51 epoxy resin, 6 g dibutyl phthalate, 5 g quartz sand, 5 g titanium dioxide, 2 g talc, and 2 g fumed silica were added in sequence, placed in a grinder, and ground for 60 min to obtain component A;

[0058] (2) Weigh 30 g of a modified curing agent, 15 g of xylene, 3 g of ethanol, 10 g of triethanolamine, 3 g of quartz sand, 3 g of titanium dioxide, 2 g of talc and 1 g of fumed silica, respectively, put them into a disperser and stir for 60 min to obtain component B;

[0059] (3) Weigh 100 g of component A and 80 g of component B respectively, mix them, and grind them for 30 minutes to prepare an epoxy resin adhesive.

[0060] Example 4

[0061] A method for preparing a modified polyacrylamide curing agent for epoxy resin comprises the following steps:

[0062] (1) 30.5 g of acrylamide monomer was added to a three-necked flask with a stirring device and a condenser, and then 380 g of acetone solvent was added. After completion, the temperature was raised, the water bath temperature was adjusted to 50° C., and the stirring speed was adjusted to 900 rpm until the mixture was uniformly stirred. At the same time, 0.25 g of azobisisoheptanenitrile and 45 g of acetone were mixed and placed in a constant pressure dropping funnel. The mixture was added dropwise to the three-necked flask at a rate of 40 drops / min using the constant pressure dropping funnel, and the mixture was reacted for 15 min.

[0063] (2) 0.19 g of ammonia water was added to adjust the pH to 9, and then 4.0 g of ethylene glycol and 12.8 g of 3-methacryloxypropyltris(trimethylsiloxysilyl)silane were mixed evenly and added dropwise to the three-necked flask at a rate of 35 drops / min using a constant pressure dropping funnel. The reaction was continued for 4.5 h, and then the temperature was lowered to obtain a viscous product.

[0064] A preparation method of an epoxy resin adhesive comprises the following steps:

[0065] (1) In a 1L grinding jar, 100 g F44 epoxy resin, 5 g n-butyl glycidyl ether, 5 g silica powder, 5 g alumina powder, 2 g talc powder, and 2 g fumed silica were added in sequence, placed in a grinder, and ground for 60 min to obtain component A;

[0066] (2) Weigh 55 g of a modified curing agent, 12 g of benzyl alcohol, 9 g of benzyldimethylamine, 7 g of silica powder, 4 g of alumina powder, 1 g of talc and 2 g of fumed silica, respectively, put them into a disperser and stir for 60 min to obtain component B;

[0067] (3) Weigh 100 g of component A and 70 g of component B respectively, mix them, and grind them for 30 minutes to prepare an epoxy resin adhesive.

[0068] Comparative Example 1

[0069] A method for preparing a modified polyacrylamide curing agent for epoxy resin comprises the following steps:

[0070] (1) 30.5 g of acrylamide monomer was added to a three-necked flask with a stirring device and a condenser, and then added to 305 g of acetone solvent. After completion, the temperature was raised, the water bath temperature was adjusted to 50° C., and the stirring speed was adjusted to 600 rpm until the stirring was uniform. At the same time, 0.16 g of azobisisoheptanenitrile and 60.5 g of acetone were mixed and placed in a constant pressure dropping funnel. The mixture was added dropwise to the three-necked flask at a rate of 20 drops / min using the constant pressure dropping funnel, and the reaction was continued for 15 min.

[0071] (2) 0.18 g of ammonia water was added to adjust the pH to 8, and then 1.83 g of ethylene glycol and 3.05 g of 3-methacryloxypropylmethyldimethoxysilane were mixed evenly and added dropwise to the three-necked flask at a rate of 15 drops / min using a constant pressure dropping funnel. The reaction was continued for 5 h, and then the temperature was lowered to obtain a viscous product.

[0072] A preparation method of an epoxy resin adhesive comprises the following steps:

[0073] (1) In a 1L grinding jar, 100 g of E51 epoxy resin, 8 g of n-butyl glycidyl ether, 5 g of alumina powder, 5 g of calcium powder, 2 g of glass fiber, and 2 g of fumed silica were added in sequence, placed in a grinder, and ground for 60 min to obtain component A;

[0074] (2) Weigh 60 g of a modified curing agent, 5 g of benzyl alcohol, 10 g of 2,4,6-tris(dimethylaminomethyl)phenol, 5 g of alumina powder, 2 g of calcium powder, 3 g of glass fiber and 1 g of fumed silica, respectively, put them into a disperser and stir for 60 min to obtain component B;

[0075] (3) Weigh 100 g of component A and 60 g of component B respectively, mix them, and grind them for 30 minutes to prepare an epoxy resin adhesive.

[0076] Comparative Example 2

[0077] A preparation method of an epoxy resin adhesive comprises the following steps:

[0078] (1) In a 1L grinding jar, 100 g of E51 epoxy resin, 10 g of phenyl glycidyl ether, 20 g of silicon powder, 3 g of titanium dioxide, 5 g of mica powder, and 2 g of fumed silica were added in sequence, placed in a grinder, and ground for 60 min to obtain component A;

[0079] (2) Weigh 50 g of polyacrylamide, 1.8 g of 3-methacryloxypropyltriethoxysilane, 25 g of acetone, 3 g of 2-ethyl-4-methylimidazole, 15 g of silica powder, 3 g of titanium dioxide and 1 g of mica powder respectively, put them into a disperser and stir for 60 min to obtain component B;

[0080] (3) Weigh 100 g of component A and 70 g of component B respectively, mix them, and grind them for 30 minutes to prepare an epoxy resin adhesive.

[0081] The physical property parameters of the modified polyacrylamide curing agent for epoxy resin prepared in Examples 1 to 4 are shown in Table 1.

[0082] Table 1 Physical properties of the modified polyacrylamide curing agent for epoxy resin prepared in Examples 1 to 4

[0083] Physical state Light yellow viscous Solid content (%) 45～80 Viscosity 6~7Pa·s Thinner Ethanol and other organic solvents Storage period 12 months

[0084] The adhesives prepared in Examples 1 to 4 and Comparative Examples 1 to 2 were subjected to performance tests by coating the adhesives on the surface of sandblasted steel sheet specimens and concrete test blocks and curing them at room temperature for 7 days. The test items included steel-to-steel shear strength, impact strength, steel-to-dry concrete (C45) positive tensile bond strength, steel-to-wet concrete (C45) positive tensile bond strength, shrinkage, and compressive strength.

[0085] The test methods for steel-to-steel shear strength, impact strength, steel-to-dry concrete (C45) tensile bond strength, shrinkage rate and compressive strength refer to GB / T 7124-2008, GB / T 6328-2021, Appendix G of GB / T 50728-2011, ISO3512-1997 and GB / T 2567-2021 respectively; the test method for steel-to-dry concrete (C45) tensile bond strength refers to Table 4.6.4 of GB / T50728-2011. After the C45 concrete specimen is soaked in water for 48 hours, the adhesive is prepared according to the proportion and immediately bonded to the freshly taken concrete specimen. After curing for 7 days under a standard laboratory environment, the tensile bond strength is determined according to Appendix G of GB / T50728-2011. The test results are shown in Table 2.

[0086] Table 2 Test results of adhesive performance indicators of Examples 1 to 4 and Comparative Examples 1 to 2

[0087]

[0088] From Table 2, it can be seen that the steel-to-steel shear strength of the adhesives in Examples 1 to 4 of the present application is 23.6 to 24.0 MPa, and the impact strength is 15.5 to 16.4 KJ / m 2 The positive tensile bonding strength of steel to dry concrete (C45) is 10.8~11.9MPa and it is cohesive failure of concrete. The positive tensile bonding strength of steel to dry concrete (C45) is 2.8~11.9MPa. The positive tensile bonding strength of steel to wet concrete (C45) is 10.5~10.8MPa. The shrinkage rate is 0.04%~0.08%, and the compressive strength is 106.2MPa~111.0MPa.

[0089] Comparative Example 1: An acryloxy silane having one less methoxy group in its molecular structure than that of the acryloxy silane in Example 1 was used to modify the curing agent. As shown in Table 2, compared with Example 1, the bonding strength of the steel in Comparative Example 1 to dry concrete is almost unchanged, but the bonding strength reduction rate of the steel to wet concrete is about 10%, and the compressive strength reduction rate is about 15%. Its moisture resistance decreases, but compared with the dry bonding strength, its bonding strength retention rate after wet bonding is still above 85%. The above data show that the modified polyacrylamide curing agent prepared in the example contains silanols that can be hydrolyzed into silanols. The silanols react with the metal hydroxyl groups on the surface of the inorganic material to form a silanol structure and remove water, so that a dense silane layer can be formed on the surface of the inorganic material, so that the surface of the inorganic material is further away from the interface, greatly improving the interfacial bonding ability and mechanical strength.

[0090] Comparative Example 2: In the epoxy resin system, acryloxy silane and polyacrylamide curing agent are directly added to prepare an adhesive. Compared with the adhesive prepared in Example 2, the steel-to-steel shear strength decreases by about 60%, the positive tensile bonding strength decreases by 67%, and the compressive strength decreases by about 40%, and the comprehensive performance is greatly reduced. The reason is that acryloxy silane contains unsaturated carbon-carbon double bonds, which are linked to polyacrylamide in a chemical bonding manner, greatly improving the stability and mechanical strength of the epoxy matrix.

Claims

1. A modified polyacrylamide curing agent for epoxy resin, characterized in that: The structural formula is: wherein n is 20 to 200; R is methyl, ethyl or trimethylsiloxane; The number average molecular weight of the modified polyacrylamide curing agent is 10 4 ~10 5 .

2. The method for preparing a modified polyacrylamide curing agent for epoxy resin according to claim 1, characterized in that: The following steps are involved: (1) Add acrylamide monomer to solvent, raise the temperature to no more than 50° C., adjust the stirring speed to 500-1000 rpm until the mixture is uniformly stirred, and simultaneously dropwise add a mixture of initiator and solvent, and react for 15-60 minutes; (2) Ammonia water is added to adjust the pH to 8-10, and then a mixed solution of a hydrolysis inhibitor and acryloxy-type oxysilane is added dropwise, reacting for 2-6 hours, and then cooling to room temperature to obtain a viscous product.

3. The preparation method according to claim 2, characterized in that: The acryloxy silane in step (2) is one of 3-methacryloxypropyl trimethoxysilane, 3-acryloxypropyl trimethoxysilane, 3-methacryloxypropyl triethoxysilane, and 3-methacryloxypropyl tris(trimethylsiloxysilyl)silane, and the amount used is 10wt% to 60wt% of acrylamide.

4. The preparation method according to claim 3, characterized in that: The hydrolysis inhibitor in step (2) is ethylene glycol, and the amount used is 6wt% to 15wt% of acrylamide.

5. The preparation method according to claim 2, characterized in that: The solvent in step (1) is acetone, the amount of the solvent added to the acrylamide monomer is 10 to 15 times the mass of the acrylamide, and the amount of the solvent mixed with the initiator is 1 to 5 times the mass of the acrylamide.

6. The preparation method according to claim 5, characterized in that: The initiator in step (1) is azobisisoheptanonitrile, and the amount used is 0.5wt% to 1wt% of acrylamide.

7. The preparation method according to claim 6, characterized in that: The amount of ammonia water used in step (2) is 0.5wt% to 1.5wt% of acrylamide.

8. An epoxy resin adhesive, characterized in that: It is composed of component A and component B in a mass ratio of 1:(0.6-0.8); The component A is composed of 100 parts of epoxy resin, 3 to 20 parts of diluent and 3 to 30 parts of mixed filler; The component B is composed of 30 to 60 parts of the modified polyacrylamide curing agent according to claim 1, 5 to 25 parts of a diluent, 3 to 15 parts of an accelerator, and 3 to 20 parts of a mixed filler.

9. The epoxy resin adhesive according to claim 8, characterized in that: The epoxy resin is bisphenol A epoxy resin or bisphenol F epoxy resin.

10. The method for preparing the epoxy resin adhesive according to claim 8, characterized in that: Specifically, the A component is mixed and ground for 60 to 120 minutes, the B component is mixed and stirred for 60 to 120 minutes, and then the A component and the B component are mixed according to weight and ground for 10 to 30 minutes to prepare the epoxy resin adhesive.

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