Low-temperature curing epoxy adhesive and preparation method thereof

Abstract

The invention relates to the technical field of epoxy adhesives, in particular to a low-temperature curing epoxy adhesive and a preparation method thereof. The epoxy resin composition comprises the following components in parts by weight: 30-80 parts of epoxy resin, 20-40 parts of a curing agent and 0.1-2 parts of an accelerant, the accelerant comprises a zeolite imidazate framework material. Zinc ions and 2-methylimidazole are coordinated and self-assembled to form a porous crystal material, and the porous crystal material is used as an accelerant, so that the storage stability of the epoxy adhesive can be improved; the particle size of the accelerant is 50-250 nm, the pore diameter is 0.2-1 nm, the pore volume is 0.3-1 cm < 3 > / g, and the addition amount of the accelerant can be reduced; the accelerator prepared by the invention is simple and convenient in synthesis method, is used in an epoxy adhesive formula, and can improve the adhesion and reduce the shrinkage rate.

Description

Technical Field

[0001] The present invention relates to the technical field of epoxy adhesives, and in particular to a low-temperature curing epoxy adhesive and a preparation method thereof. Background Art

[0002] The bonding process of epoxy adhesive is a complex physical and chemical process, including steps such as wetting, adhesion, and curing, and finally generates a three-dimensional cross-linked structure to achieve bonding. Among them, imidazole, as a commonly used curing agent, has high curing activity and can significantly improve the performance of epoxy resin curing system. With the rise of nano systems, more and more nano materials have emerged, and there are few reports on the changes in the structure of epoxy adhesives by nano materials to improve the cross-linking reaction structure and curing conditions.

[0003] Chinese invention patent CN 117757387A provides an epoxy adhesive and its preparation method and application. The raw materials of the epoxy adhesive include, by mass, 62-80 parts of epoxy-terminated polybutadiene, 24-37 parts of epoxy resin, 1-20 parts of fumed silica, 16-26 parts of curing agent, 1-10 parts of diluent, 0.5-3 parts of coupling agent, and 0.5-5 parts of curing accelerator. The epoxy adhesive has excellent elastic properties and strength in a low temperature environment, but it uses traditional imidazole accelerators. Most imidazole compounds are crystalline solid powders with high melting points, which are difficult to mix with liquid epoxy resins and have poor process performance. Imidazole curing agents have certain volatility and hygroscopicity at high temperatures, and there are fewer varieties, which cannot meet special construction processes and certain specific requirements for cured products. Summary of the invention

[0004] The first aspect of the present invention provides a low-temperature curing epoxy adhesive, which comprises, by weight, 30-80 parts of epoxy resin, 20-40 parts of curing agent, and 0.1-2 parts of accelerator; the accelerator comprises a zeolite imidazolate framework material.

[0005] The particle size of the promoter is 50-250 nm.

[0006] Preferably, the particle size of the promoter is 50-100 nm.

[0007] The pore size of the promoter is 0.2-1 nm, and the pore volume is 0.3-1 cm 3 / g.

[0008] Preferably, the pore size of the promoter is 0.2-0.6 nm and the pore volume is 0.5-1 cm 3 / g.

[0009] The applicant has found that the porous crystalline material self-assembled by the coordination of zinc ions and 2-methylimidazole can improve the storage stability of epoxy adhesives as a promoter. This may be because the porous crystalline material has a large specific surface area, high porosity, and controllable size, especially its nanostructure is conducive to dispersion in the system. At the same time, since the use of imidazole promoters is avoided, the biocompatibility is further improved, it has good stability under physiological conditions, and disintegrates under acidic conditions, and is responsive to weakly acidic environments.

[0010] Preferably, the epoxy resin comprises bisphenol epoxy resin.

[0011] The epoxy equivalent of the bisphenol epoxy resin is 150-250 g / mol, and the viscosity at 25° C. is 10000-20000 cps.

[0012] Preferably, the bisphenol epoxy resin has an epoxy equivalent of 180-200 g / mol and a viscosity of 12000-15000 cps at 25°C.

[0013] The weight ratio of the epoxy resin to the accelerator is 50:(0.1-1).

[0014] Preferably, the weight ratio of the epoxy resin to the accelerator is 50:(0.5-1).

[0015] The weight ratio of the epoxy resin to the curing agent is 5:(3-4).

[0016] Preferably, the weight ratio of the epoxy resin to the curing agent is 5:(3.3-3.6).

[0017] The curing agent has one or more hydroxyl groups and two or more thiol groups.

[0018] Preferably, the curing agent includes trimethylolpropane bis(thioglycolate), trimethylolpropane bis(3-mercaptopropionate), trimethylolpropane bis(3-mercaptobutyrate), trimethylolpropane bis(4-mercaptobutyrate), pentaerythritol bis(thioglycolate), pentaerythritol bis(3-mercaptopropionate), pentaerythritol bis(3-mercaptobutyrate), pentaerythritol bis(4-mercaptobutyrate), pentaerythritol tris(thioglycolate), pentaerythritol tris(3-mercaptopropionate), pentaerythritol tris(3-mercaptobutyrate), pentaerythritol tris(4-mercaptobutyrate), dipentaerythritol bis(thioglycolate), dipentaerythritol bis(3-mercaptopropionate), dipentaerythritol At least one of pentaerythritol bis(3-mercaptobutyrate), dipentaerythritol bis(4-mercaptobutyrate), dipentaerythritol tris(thioglycolate), dipentaerythritol tris(3-mercaptopropionate), dipentaerythritol tris(3-mercaptobutyrate), dipentaerythritol tris(4-mercaptobutyrate), dipentaerythritol tetrakis(thioglycolate), dipentaerythritol tetrakis(3-mercaptopropionate), dipentaerythritol tetrakis(3-mercaptobutyrate), dipentaerythritol tetrakis(4-mercaptobutyrate), dipentaerythritol penta(thioglycolate), dipentaerythritol penta(3-mercaptopropionate), dipentaerythritol penta(3-mercaptobutyrate), and dipentaerythritol penta(4-mercaptobutyrate).

[0019] Preferably, the curing agent comprises trimethylolpropane tris(3-mercaptopropionate) and / or pentaerythritol tetrakis(3-mercaptopropionate).

[0020] The second aspect of the present invention provides a method for preparing a low-temperature curing epoxy adhesive, comprising the following steps: mixing an epoxy resin and a curing agent, and then adding an accelerator and stirring to obtain the epoxy adhesive.

[0021] Beneficial Effects

[0022] 1. The porous crystalline material self-assembled by the coordination of zinc ions and 2-methylimidazole can be used as a promoter to improve the storage stability of epoxy adhesives.

[0023] 2. The particle size of the accelerator is 50-250nm, the pore size is 0.2-1nm, and the pore volume is 0.3-1cm 3 / g, which can reduce the amount of accelerator added.

[0024] 3. The accelerator prepared in this application has a simple synthesis method and can be used in epoxy adhesive formulations to improve adhesion and reduce shrinkage.

[0025] 4. The epoxy adhesive prepared in this application can be cured at a low temperature below 150°C.

[0026] 5. The epoxy adhesive prepared in this application has excellent biocompatibility. DETAILED DESCRIPTION

[0027] Example 1

[0028] A low-temperature curing epoxy adhesive, comprising, by weight, 50 parts of epoxy resin (selected from Guangzhou Yihuisheng Chemical Co., Ltd., model GELR-128), 36 parts of curing agent (trimethylolpropane tris (3-mercaptopropionate)), and 1 part of accelerator; the accelerator is a zeolite imidazolate skeleton material, and the accelerator has a particle size of 80 nm, a pore size of 0.34 nm, and a pore volume of 0.66 cm 3 / g.

[0029] The epoxy equivalent of the epoxy resin is 180-190 g / mol, and the viscosity at 25° C. is 12000-15000 cps.

[0030] Preparation of the promoter: 0.7134 g Zn(CH4;COO)2·2H2O and 2.1402 g Hmim (methylimidazole) were dissolved in 150 mL and 200 mL methanol, respectively; the Zn(CH4;COO)2·2H2O solution was quickly poured into the Hmim solution, stirred for 10 min, and allowed to stand at room temperature for 48 h. The product was recorded as ZIF-8-M; the product was separated from the emulsion dispersion by centrifugation (4000 rpm, 30 min), washed 3 times with methanol, and the product was dried in air at 55°C for 48 h.

[0031] A preparation method of a low-temperature curing epoxy adhesive comprises the following steps: mixing epoxy resin and curing agent, adding an accelerator, and then putting the mixture into a planetary mixer for stirring to obtain the adhesive.

[0032] Example 2

[0033] A low-temperature curing epoxy adhesive, comprising, by weight, 50 parts of epoxy resin (selected from Guangzhou Yihuisheng Chemical Co., Ltd., model GELR-128), 33 parts of curing agent (pentaerythritol tetrakis(3-mercaptopropionic acid) ester), and 0.5 parts of accelerator; the accelerator is a zeolite imidazolate skeleton material, and the accelerator has a particle size of 80 nm, a pore size of 0.34 nm, and a pore volume of 0.66 cm 3 / g.

[0034] The epoxy equivalent of the epoxy resin is 180-190 g / mol, and the viscosity at 25° C. is 12000-15000 cps.

[0035] Preparation of the promoter: 0.7134 g Zn(CH4;COO)2·2H2O and 2.1402 g Hmim (methylimidazole) were dissolved in 150 mL and 200 mL methanol, respectively; the Zn(CH4;COO)2·2H2O solution was quickly poured into the Hmim solution, stirred for 10 min, and allowed to stand at room temperature for 48 h. The product was recorded as ZIF-8-M; the product was separated from the emulsion dispersion by centrifugation (4000 rpm, 30 min), washed with methanol 3 times, and the product was dried in air at 55°C for 48 h.

[0036] A preparation method of a low-temperature curing epoxy adhesive comprises the following steps: mixing epoxy resin and curing agent, adding an accelerator, and then putting the mixture into a planetary mixer for stirring to obtain the adhesive.

[0037] Comparative Example 1

[0038] An epoxy adhesive, the components of which are, by weight, 50 parts of epoxy resin (selected from Guangzhou Yihuisheng Chemical Co., Ltd., model GELR-128), 36 parts of curing agent (trimethylolpropane tris (3-mercaptopropionate)), and 2.5 parts of accelerator (selected from Shanghai Jizhi Biochemical Technology 2 Co., Ltd., model M56340).

[0039] The epoxy equivalent of the epoxy resin is 180-190 g / mol, and the viscosity at 25° C. is 12000-15000 cps.

[0040] The invention discloses a preparation method of epoxy adhesive, which comprises the following steps: mixing epoxy resin and curing agent, adding accelerator, and then putting into a planetary mixer for stirring to obtain the epoxy adhesive.

[0041] Comparative Example 2

[0042] An epoxy adhesive, the components of which are, by weight, 50 parts of epoxy resin (selected from Guangzhou Yihuisheng Chemical Co., Ltd., model GELR-128), 33 parts of curing agent (pentaerythritol tetrakis(3-mercaptopropionic acid) ester), and 2.5 parts of accelerator (selected from Shanghai Jizhi Biochemical Technology Co., Ltd., model M56340).

[0043] The epoxy equivalent of the epoxy resin is 180-190 g / mol, and the viscosity at 25° C. is 12000-15000 cps.

[0044] The invention discloses a preparation method of epoxy adhesive, which comprises the following steps: mixing epoxy resin and curing agent, adding accelerator, and then putting into a planetary mixer for stirring to obtain the epoxy adhesive.

[0045] Performance Testing Methods

[0046] The performance of the products prepared in the embodiments and comparative examples was tested, and the test data are listed in Table 1.

[0047] Performance test data

[0048] Table 1

[0049] Experimental Example 1 Experimental Example 2 Comparative Example 1 Comparative Example 2 Tg / ℃ 52.05 67.29 40.84 57.47 Storage stability / h 72 240 8 18 Curing conditions 120℃ / 30min 135℃ / 90min 80℃ / 30min 100℃ / 40min

Claims

1. A low temperature curing epoxy adhesive, characterized in that: The components include, by weight: 30-80 parts of epoxy resin, 20-40 parts of curing agent, and 0.1-2 parts of accelerator; the accelerator includes zeolite imidazolate framework material.

2. The low temperature curing epoxy adhesive according to claim 1, characterized in that: The particle size of the promoter is 50-250 nm.

3. The low temperature curing epoxy adhesive according to claim 2, characterized in that: The pore size of the promoter is 0.2-1 nm, and the pore volume is 0.3-1 cm 3 / g.

4. The low temperature curing epoxy adhesive according to claim 1 or 3, characterized in that: The epoxy resin includes a bisphenol type epoxy resin.

5. The low temperature curing epoxy adhesive according to claim 4, characterized in that: The epoxy equivalent of the bisphenol epoxy resin is 150-250 g / mol, and the viscosity at 25° C. is 10000-20000 cps.

6. The low temperature curing epoxy adhesive according to claim 5, characterized in that: The weight ratio of the epoxy resin to the accelerator is 50:(0.1-1).

7. The low temperature curing epoxy adhesive according to claim 6, characterized in that: The weight ratio of the epoxy resin to the curing agent is 5:(3-4).

8. The low temperature curing epoxy adhesive according to claim 1, characterized in that: The curing agent has one or more hydroxyl groups and two or more thiol groups.

9. The low temperature curing epoxy adhesive according to claim 8, characterized in that: The curing agent includes trimethylolpropane bis(thioglycolate), trimethylolpropane bis(3-mercaptopropionate), trimethylolpropane bis(3-mercaptobutyrate), trimethylolpropane bis(4-mercaptobutyrate), pentaerythritol bis(thioglycolate), pentaerythritol bis(3-mercaptopropionate), pentaerythritol bis(3-mercaptobutyrate), pentaerythritol bis(4-mercaptobutyrate), pentaerythritol tris(thioglycolate), pentaerythritol tris(3-mercaptopropionate), pentaerythritol tris(3-mercaptobutyrate), pentaerythritol tris(4-mercaptobutyrate), dipentaerythritol bis(thioglycolate), dipentaerythritol bis(3-mercaptopropionate), dipentaerythritol At least one of tetraol bis(3-mercaptobutyrate), dipentaerythritol bis(4-mercaptobutyrate), dipentaerythritol tris(thioglycolate), dipentaerythritol tris(3-mercaptopropionate), dipentaerythritol tris(3-mercaptobutyrate), dipentaerythritol tris(4-mercaptobutyrate), dipentaerythritol tetrakis(thioglycolate), dipentaerythritol tetrakis(3-mercaptopropionate), dipentaerythritol tetrakis(3-mercaptobutyrate), dipentaerythritol tetrakis(4-mercaptobutyrate), dipentaerythritol penta(thioglycolate), dipentaerythritol penta(3-mercaptopropionate), dipentaerythritol penta(3-mercaptobutyrate), and dipentaerythritol penta(4-mercaptobutyrate).

10. A method for preparing the low temperature curing epoxy adhesive according to any one of claims 1 to 9, characterized in that: The method comprises the following steps: mixing epoxy resin and curing agent, adding accelerator and stirring to obtain epoxy adhesive.