Epoxy curing agent, preparation method and application thereof in epoxy resin adhesive

Abstract

The present invention discloses an epoxy curing agent, a preparation method, and its application in epoxy resin adhesives. The epoxy curing agent has the structural expression shown below. The epoxy curing agent is a derivative of trichlorohydroxydiphenyl ether and possesses both phenolic hydroxyl groups and multiple active amino groups. This curing agent not only crosslinks with epoxy resins to provide a long-lasting, mold-resistant effect, but also facilitates the curing of epoxy resins, making it more suitable for use in extreme environments. #imgabs0#

Description

Technical Field

[0001] The present invention relates to a mildew-proof epoxy curing agent, in particular to an epoxy curing agent, a preparation method and application thereof in epoxy resin adhesives. Background Art

[0002] Epoxy resin is a general term for oligomers containing epoxy groups. After reacting with a curing agent, it forms a three-dimensional cross-linked network structure and is widely used in construction coatings, adhesives, and other fields. However, in humid construction environments such as bridges, dams, and offshore drilling platforms, epoxy curing agents are susceptible to corrosion by microorganisms in the water, causing mold and mildew. This can lead to decreased adhesion, reduced mechanical properties, and a shortened service life, ultimately losing their ability to protect the substrate. Therefore, the development of mildew-resistant, highly cross-linked epoxy curing agents is crucial to ensuring the application of adhesives in high-end applications such as bridges, dams, and offshore drilling platforms.

[0003] Most existing technologies, such as the solution in CN112877016A, directly mix the mildew inhibitor with epoxy resin to prepare the adhesive. However, small molecule mildew inhibitors easily migrate to the surface of the material and do not have a long-term mildew-proof effect. In addition, the mildew-proof effects of different mildew inhibitors vary significantly.

[0004] To improve the durability of the mildew-proofing effect, patent CN112280401A treats the mildew-proofing agent with microcapsules and hydrophobically modified starch loading before mixing it with the remaining coating components. However, the mildew-proofing agent is still added by physical blending, and the duration of the mildew-proofing effect is expected to be limited. In addition, this solution has no beneficial effect on the cross-linking density of the curing system.

[0005] Patent CN111662616A adds a benzoxazine prepolymer and an antimicrobial agent to a matrix resin such as an epoxy resin. The antimicrobial agent reacts with the benzoxazine prepolymer during the thermal curing process to form a stable chemical bond, thereby producing a non-leaching antimicrobial material. However, this approach requires the addition of a large dose of thermosetting phenolic resin (benzoxazine prepolymer) to modify the epoxy resin, which has certain limitations when used to prepare a single epoxy resin. Furthermore, the single active functional group forms an end cap with the epoxy resin, preventing crosslinking and chain extension. This significantly reduces the heat resistance and mechanical properties of the cured product, causing it to peel from the substrate under strong shear forces. This makes it unsuitable for construction environments with high mechanical property requirements, such as bridges, dams, and offshore drilling platforms. Summary of the Invention

[0006] To address the above technical problems, the present invention provides an epoxy curing agent, a preparation method, and its use in epoxy resin adhesives. The epoxy curing agent is a derivative of trichlorohydroxydiphenyl ether and possesses both phenolic hydroxyl groups and multiple active amino groups. This curing agent not only crosslinks with epoxy resins to provide a long-lasting, mold-proofing effect without shedding, but also facilitates the curing of epoxy resins due to the phenolic hydroxyl groups, making it more suitable for use in extreme environments.

[0007] To achieve the above object, the technical solutions adopted by the present invention are as follows:

[0008] An epoxy curing agent having the structural expression shown in Formula I:

[0009]

[0010] Wherein, R1 is any one of H, methyl and phenyl; R2 is In either case, the wavy line indicates only the connection location.

[0011] The present invention also provides the use of the epoxy curing agent described above in a mildew-resistant epoxy resin adhesive. The epoxy curing agent has multiple active functional groups that can participate in the curing reaction of the epoxy resin, introducing mildew-resistant factors into the epoxy resin adhesive material through chemical bonding, avoiding the migration of the mildew-resistant agent and the reduction of mildew resistance caused by direct physical addition, thereby achieving a long-term mildew-resistant effect. Moreover, the multiple reactive functional groups can cross-link and cure with the epoxy groups, significantly improving the material's mechanical properties such as adhesion, tensile strength, and flexural strength, as well as heat resistance, and can meet the requirements of the material for use in harsh environments such as bridge and dam repair and offshore drilling platform reinforcement.

[0012] As a preferred embodiment of the present invention, the mildew-proof epoxy resin adhesive comprises component A and component B;

[0013] Based on the total mass of component A, component A includes:

[0014] Epoxy resin 57-78wt%; preferably 60-75wt%,

[0015] Diluent 8-30wt%; preferably 10-25wt%,

[0016] Leveling agent 5-17wt%, preferably 11-15wt%;

[0017] Based on the total mass of component B, component B includes:

[0018] Epoxy curing agent 67-83wt%, preferably 70-80wt%,

[0019] Solvent 17-33wt%, preferably 20-30wt%.

[0020] As a preferred solution for application of the present invention, the mass ratio of component A to component B is (1-10):1, preferably (2-8):1.

[0021] As a preferred embodiment of the present invention, the epoxy resin is a bisphenol A type and / or bisphenol F type epoxy resin, preferably selected from a bisphenol A type epoxy resin having an epoxy value of 0.1-0.65 and being liquid at room temperature, and a bisphenol F type epoxy resin having an epoxy value of 0.1-0.65 and being liquid at room temperature;

[0022] And / or, the diluent is selected from the group consisting of 12 -C 14 One or more of alkyl glycidyl ether, butyl glycidyl ether, benzyl glycidyl ether, 1,4-butanediol diglycidyl ether, 1,6-hexanediol diglycidyl ether, 1,2-cyclohexanediol diglycidyl ether, polyethylene glycol diglycidyl ether, trimethylolpropane triglycidyl ether, benzyl alcohol, phenylethyl alcohol, nonylphenol, propylene carbonate, trimethylolpropane triacrylate, diisopropyl alcohol methyl ether, toluene and xylene;

[0023] and / or, the leveling agent is one or more of polyacrylate and modified silicone, preferably one or more of BYK388, BYK320, BYK358N and BYK392;

[0024] And / or, the solvent is one or more of benzene, toluene, xylene and acetone.

[0025] The preparation method of the mildew-proof epoxy resin adhesive can refer to any known existing method, or make simple adjustments and improvements based on the known process, for example, including:

[0026] Add epoxy resin, diluent and leveling agent into the mixing equipment, heat and stir to obtain component A; then mix and stir the epoxy curing agent and solvent to obtain component B; during construction, mix components A and B as needed.

[0027] Preferably, the mixing condition of component A is stirring at 35-70° C. for 1-5 hours, preferably stirring at 40-65° C. for 2-4 hours.

[0028] Preferably, the mixing condition of component B is stirring at 30-60° C. for 1-5 hours, preferably stirring at 35-55° C. for 2-4 hours.

[0029] The present invention also provides a method for preparing the epoxy curing agent as described above, by which the epoxy curing agent can be prepared with high selectivity and the process flow is simple, and the method comprises the following steps:

[0030] S1, mixing 2,4,4'-trichloro-2'-hydroxy-diphenyl ether and the compound represented by formula II uniformly;

[0031] S2, adding the compound represented by formula III to the mixture obtained in S1, reacting with stirring to obtain the epoxy curing agent represented by formula I;

[0032]

[0033] NH2-R2-NH2 Formula II

[0034] CHO-R1 Formula III

[0035] Wherein, R1 is any one of H, methyl and phenyl; R2 is In either case, the wavy line indicates only the connection location.

[0036] As a preferred embodiment of the preparation method of the present invention, the molar ratio of 2,4,4'-trichloro-2'-hydroxy-diphenyl ether to the compound represented by formula II in S1 is 1:(0.9-1.1), preferably 1:(0.95-1.05).

[0037] As a preferred embodiment of the preparation method of the present invention, the raw materials in S1 are mixed and then heated to 40-110°C, preferably 45-95°C.

[0038] As a preferred embodiment of the preparation method of the present invention, the molar ratio of the compound represented by formula III in S2 to 2,4,4'-trichloro-2'-hydroxy-diphenyl ether is 1:(0.9-1.1), preferably 1:(0.95-1.05).

[0039] As a preferred embodiment of the preparation method of the present invention, the reaction temperature in S2 is 50-130° C., preferably 80-90° C., and the reaction time is 4-9 h, preferably 5-7 h.

[0040] From the perspective of curing agent structural design, the present invention develops a compound that simultaneously contains an anti-mildew factor, phenolic hydroxyl groups, and multiple active amino groups. When used as a curing agent for an epoxy resin adhesive, on the one hand, the anti-mildew factor can be introduced into the epoxy resin adhesive material through chemical bond bonding, avoiding the migration of the anti-mildew agent and the reduction of mildew resistance caused by direct physical addition, thereby playing a long-term mildew-proof role. On the other hand, the multiple active amino groups can increase the cross-linking density of the epoxy resin, significantly improving the heat resistance, tensile strength, flexural strength, and adhesion of the cured product, thereby meeting the requirements of fields with high mechanical properties, such as bridge and dam repair and offshore drilling platform reinforcement. In addition, the phenolic hydroxyl group can also promote the curing of the epoxy resin, accelerate the curing process, and make construction more convenient. DETAILED DESCRIPTION

[0041] The present invention will be further described below through specific examples. The examples of the present invention are only for illustration of the present invention and do not limit the scope of the present invention.

[0042] The main raw materials used in the following examples of the present invention are shown in Table 1. Other raw materials and reagents were obtained from commercial sources unless otherwise specified.

[0043] Table 1. Main raw material information

[0044]

[0045] The main test methods and equipment used in the following embodiments of the present invention are as follows:

[0046] Curing time: Place 100g of newly prepared epoxy resin adhesive in a 50cm*50cm*4mm mold and measure the time required for the sample to reach a hardness of 80D at 40°C.

[0047] Adhesion: GB / T5120-2006, BGD500 of Biaogeda Precision Instrument Co., Ltd.

[0048] Mechanical properties: Tensile strength and flexural strength tests were conducted according to GB / T 2567-2008, Shanghai Hengke Instrument Co., Ltd. (SHK);

[0049] Heat deflection temperature: ASTM D648, Tianjin Meters TSY-44;

[0050] Anti-mildew performance: GB / T1741-2007, LHS-70SC constant temperature and humidity incubator (70L).

[0051] [Example 1]

[0052]

[0053] Preparation of epoxy curing agent A:

[0054] S1: Under nitrogen protection, 1 mol of 2,4,4'-trichloro-2'-hydroxy-diphenyl ether and 0.95 mol of 1,2-cyclohexanediamine were mixed evenly and the temperature was raised to 95°C.

[0055] S2: Add 0.9 mol of formaldehyde solution (35 wt%) to the mixture obtained in S1, and react at 80° C. for 7 h to obtain epoxy curing agent A.

[0056] 13CNMR (CDCl3, 600MHz, TMS), δ128.8(C), 130.1(C), 127.2(C), 150.1(C), 120.3(C), 126.7(C), 145.5(C), 1 48.9(C), 124.5(C), 127.8(C), 121.0(C), 33.6(C), 57.6(C), 55.3(C), 31.7(C), 22.9(C), 23.2(C), 29.2(C)

[0057] [Example 2]

[0058] Preparation of epoxy curing agent B:

[0059] S1: Under nitrogen protection, mix 1 mol of 2,4,4'-trichloro-2'-hydroxy-diphenyl ether and 1.05 mol of 4,4'-diaminodicyclohexylmethane, and heat to 45°C.

[0060] S2: Add 1.1 mol of acetaldehyde to the mixture of S1 and react at 90°C for 5 hours to obtain epoxy curing agent B.

[0061] 13CNMR (CDCl3, 600MHz, TMS), δ128.3(C), δ126.7(C), 129.0(C), 124.0(C), 154.6(C), 143.1(C), 145.7(C), 120.6(C), 122.6 (C), 117.0(C), 120.1(C), 143.1(C), 124.1(C), 42.9(C), 51.4(C), 31.5(2C), 27.3(2C), 30.1(C), 27(2C), 33.7(2C), 48.3(C)

[0062] [Example 3]

[0063] Preparation of epoxy curing agent C:

[0064] S1: Under nitrogen protection, 1 mol of 2,4,4'-trichloro-2'-hydroxy-diphenyl ether and 1 mol of isophorone diamine were mixed evenly and the temperature was raised to 75°C.

[0065] S2: Add 1 mol of benzaldehyde to the mixture of S1 and react at 80°C for 6 hours to obtain epoxy curing agent C.

[0066] 13CNMR (CDCl3, 600MHz, TMS), δ128.8(C), 130.1(C), 127.2(C), 150.1(C), 120.3(C), 126.7(C), 145.5(C), 148.9(C), 124. 5(C), 127.8(C), 121.0(C), 33.6(C), 46.2(C), 48.6(C), 23.0(C), 27.9(2C), 51.7(C), 25.4(C), 35.8(C), 46.1(C), 34.8(C)

[0067] [Example 4]

[0068] Preparation of epoxy curing agent D:

[0069] S1: Under nitrogen protection, mix 1 mol of 2,4,4'-trichloro-2'-hydroxy-diphenyl ether and 1 mol of 4,4'-diphenylmethanediamine, and heat to 50°C.

[0070] S2: Add 1 mol of acetaldehyde to the mixture of S1 and react at 86°C for 5.5 hours to obtain epoxy curing agent D.

[0071] 13CNMR (CDCl3, 600MHz, TMS), δ128.8(C), 130.1(C), 127.2(C), 150.1(C), 120.3(C), 126.7(C), 145.5(C), 147.9(C), 129.7(C), 126.8(C), 121.0(C), 118.3(C), 27.2(C), 145.1(C), 114.0(2C), 129.1(4C), 130 .0(C), 45.8(C), 131.6(C), 129.1(C), 116.8(2C), 145.9(C), 116.8(C)

[0072] [Example 5]

[0073] Preparation of epoxy resin adhesive A:

[0074] Mix 60g of bisphenol A diglycidyl ether (epoxy value 0.51), 25g of 1,4-butanediol diglycidyl ether, and 15g of BYK-388 leveling agent to obtain component A. Mix 70g of epoxy curing agent A with 30g of xylene to obtain component B. Finally, mix components A and B in a mass ratio of 8:1 to obtain epoxy resin adhesive A.

[0075] [Example 6]

[0076] Preparation of epoxy resin adhesive B:

[0077] Mix 75g of bisphenol F diglycidyl ether (epoxy value 0.55), 10g of 1,6-hexanediol diglycidyl ether, and 15g of BYK-320 leveling agent to obtain component A. Mix 80g of epoxy curing agent B with 20g of toluene to obtain component B. Finally, mix components A and B in a mass ratio of 7:1 to obtain epoxy resin adhesive B.

[0078] [Example 7]

[0079] Preparation of epoxy resin adhesive C:

[0080] Mix 70g of bisphenol A diglycidyl ether (epoxy value 0.51), 20g of polyethylene glycol diglycidyl ether, and 10g of BYK-320 leveling agent to obtain component A. Mix 75g of epoxy curing agent C with 25g of toluene to obtain component B. Finally, mix components A and B in a mass ratio of 2:1 to obtain epoxy resin adhesive C.

[0081] [Example 8]

[0082] Preparation of epoxy resin adhesive D:

[0083] Mix 62g of bisphenol A diglycidyl ether (epoxy value 0.51), 23g of trimethylolpropane triacrylate, and 15g of BYK-320 leveling agent to obtain component A. Mix 77g of epoxy curing agent D with 23g of acetone to obtain component B. Finally, mix components A and B in a mass ratio of 5:1 to obtain epoxy resin adhesive D.

[0084] [Comparative Example 1]

[0085] An epoxy resin adhesive was prepared by a method substantially the same as in Example 7, except that the epoxy curing agent C used to prepare component B was replaced by a mixture of isophorone diamine and 2,4,4'-trichloro-2'-hydroxy-diphenyl ether in a mass ratio of 1:1.7.

[0086] The epoxy resin adhesives prepared in Examples 5-8 and Comparative Example 1 were subjected to curing time tests, mechanical property tests, and antifungal tests, and the results are shown in Table 2:

[0087] Table 2. Adhesive performance test results

[0088]

[0089]

[0090] 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 considered within the scope of protection of the present invention.

Claims

1. An epoxy curing agent, characterized in that It has the structural expression shown in formula I: Wherein, R1 is any one of H, methyl and phenyl; R2 is In either case, the wavy line indicates only the connection location.

2. Use of the epoxy curing agent as claimed in claim 1 in a mildew-proof epoxy resin adhesive.

3. The use of the epoxy curing agent according to claim 2 in a mildew-proof epoxy resin adhesive, characterized in that: The mildew-proof epoxy resin adhesive comprises component A and component B; Based on the total mass of component A, component A includes: Epoxy resin 57-78wt%; Diluent 8-30wt%; Leveling agent 5-17wt%, Based on the total mass of component B, component B includes: Epoxy curing agent 67-83wt%, Solvent 17-33wt%.

4. The use of the epoxy curing agent according to claim 3 in a mildew-proof epoxy resin adhesive, characterized in that: The mildew-proof epoxy resin adhesive comprises component A and component B; Based on the total mass of component A, component A includes: Epoxy resin 60-75wt%, Diluent 10-25wt%, Leveling agent 11-15wt%; Based on the total mass of component B, component B includes: Epoxy curing agent 70-80wt%, Solvent 20-30wt%.

5. Use of the epoxy curing agent according to claim 3 in a mildew-proof epoxy resin adhesive, characterized in that: The mass ratio of component A to component B is (1-10):

1.

6. Use of the epoxy curing agent according to claim 5 in a mildew-proof epoxy resin adhesive, characterized in that: The mass ratio of component A to component B is (2-8):

1.

7. Use of the epoxy curing agent according to any one of claims 3 to 6 in a mildew-proof epoxy resin adhesive, characterized in that: The epoxy resin is bisphenol A and / or bisphenol F epoxy resin; And / or, the diluent is selected from the group consisting of 12 -C 14 One or more of alkyl glycidyl ether, butyl glycidyl ether, benzyl glycidyl ether, 1,4-butanediol diglycidyl ether, 1,6-hexanediol diglycidyl ether, 1,2-cyclohexanediol diglycidyl ether, polyethylene glycol diglycidyl ether, trimethylolpropane triglycidyl ether, benzyl alcohol, phenylethyl alcohol, nonylphenol, propylene carbonate, trimethylolpropane triacrylate, diisopropyl alcohol methyl ether, toluene and xylene; and / or, the leveling agent is one or more of polyacrylate and modified silicone; And / or, the solvent is one or more of benzene, toluene, xylene and acetone.

8. Use of the epoxy curing agent according to claim 7 in a mildew-proof epoxy resin adhesive, characterized in that: The epoxy resin is selected from bisphenol A epoxy resin having an epoxy value of 0.1-0.65 and being liquid at room temperature, and bisphenol F epoxy resin having an epoxy value of 0.1-0.65 and being liquid at room temperature.

9. Use of the epoxy curing agent according to claim 7 in a mildew-proof epoxy resin adhesive, characterized in that: The leveling agent is one or more of BYK388, BYK320, BYK358N and BYK392.

10. A method for preparing an epoxy curing agent, characterized in that: The following steps are involved: S1, mixing 2,4,4'-trichloro-2'-hydroxy-diphenyl ether and the compound represented by formula II uniformly; S2, adding the compound represented by formula III to the mixture obtained in S1, and reacting with stirring to obtain the epoxy curing agent represented by formula I; NH2-R2-NH2 Formula II CHO-R1 Formula III Wherein, R1 is any one of H, methyl and phenyl; R2 is In either case, the wavy line indicates only the connection location.

11. The method for preparing an epoxy curing agent according to claim 10, wherein: The molar ratio of 2,4,4'-trichloro-2'-hydroxy-diphenyl ether to the compound represented by formula II in S1 is 1:(0.9-1.1).

12. The method for preparing an epoxy curing agent according to claim 11, wherein: The molar ratio of 2,4,4'-trichloro-2'-hydroxy-diphenyl ether to the compound represented by formula II in S1 is 1:(0.95-1.05).

13. The method for preparing an epoxy curing agent according to claim 11 or 12, wherein: The raw materials in S1 are mixed and heated to 40-110°C.

14. The method for preparing an epoxy curing agent according to claim 13, wherein: The raw materials in S1 are mixed and heated to 45-95°C.

15. The method for preparing an epoxy curing agent according to claim 10, wherein: The molar ratio of the compound represented by formula III in S2 to 2,4,4'-trichloro-2'-hydroxy-diphenyl ether is 1:(0.9-1.1).

16. The method for preparing an epoxy curing agent according to claim 15, wherein: The molar ratio of the compound represented by formula III in S2 to 2,4,4'-trichloro-2'-hydroxy-diphenyl ether is 1:(0.95-1.05).

17. The method for preparing an epoxy curing agent according to claim 15 or 16, wherein: The reaction temperature in S2 is 50-130°C, and the reaction time is 4-9h.

18. The method for preparing an epoxy curing agent according to claim 17, wherein: The reaction temperature in S2 is 80-90°C and the reaction time is 5-7h.

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