High-strength high-toughness high-temperature-resistant epoxy resin adhesive as well as preparation method and application thereof

Abstract

The invention relates to a high-strength high-toughness high-temperature-resistant epoxy resin adhesive as well as a preparation method and application thereof. The high-strength high-toughness high-temperature-resistant epoxy resin adhesive comprises the following components: epoxy resin, a curing agent, an organic solvent, a curing accelerator and an inorganic filler, wherein the curing accelerator is a 2-methoxy group 6-methylaminopyridine-boron trifluoride complex, and the curing accelerator is a 2-methoxy group 6-methylaminopyridine-boron trifluoride complex. According to the epoxy resin adhesive, the adopted curing accelerator can play a role in avoiding pre-curing, on the other hand, the curing temperature can be reduced, and the epoxy resin adhesive is low in preparation cost, high in process efficiency and good in modification effect and has a good market application prospect.

Description

Technical Field

[0001] The invention belongs to the technical field of adhesives, and particularly relates to a high-strength, high-toughness, high-temperature-resistant epoxy resin adhesive and a preparation method and application thereof. Background Art

[0002] Epoxy resin is one of the most common thermosetting materials. Its good thermal stability, mechanical properties, insulation, chemical resistance and adhesion have made it one of the indispensable materials in the fields of electronics, mechanical optics, chemical industry, etc. Since epoxy resin itself has a high degree of cross-linking, which leads to high brittleness of the material, a certain amount of modifiers will be added to it to improve the mechanical properties of epoxy resin, such as inorganic fillers. The increase in the content of inorganic fillers can increase the strength of epoxy resin cured adhesives, but as the content of inorganic fillers increases, the melt viscosity of the adhesive will increase during processing and reduce fluidity. This will cause bubbles or uneven thickness inside the adhesive, which will increase the risk of cracking due to internal stress during use. Summary of the invention

[0003] The technical problem to be solved by the present invention is to provide a high-strength, high-toughness, high-temperature resistant epoxy resin adhesive and a preparation method and application thereof. The curing accelerator used in the adhesive can avoid pre-curing and on the other hand can reduce the curing temperature.

[0004] The present invention provides a high-strength, high-toughness, high-temperature resistant epoxy resin adhesive, which comprises the following components in parts by weight:

[0005]

[0006] Preferably, the preparation method of the 2-methoxy 6-methylaminopyridine-boron trifluoride complex comprises the following steps: mixing 2-methoxy 6-methylaminopyridine with tetrahydrofuran to obtain a mixed solution, then dropping a boron trifluoride ether solution into the mixed solution, reacting at room temperature, washing and drying to obtain a product. The 2-methoxy 6-methylaminopyridine-boron trifluoride complex can form microcapsules with epoxy resin and achieve slow release during the curing process. Boron trifluoride and epoxy resin coexist stably, and at the melting temperature of the capsule wall material, they are quickly mixed to achieve the purpose of rapid curing and shorten the curing time. It can also serve as a chemical crosslinking point and stress absorption point to effectively enhance and toughen the epoxy resin adhesive and improve its mechanical properties.

[0007] Preferably, the curing agent is an acid anhydride curing agent. More preferably, the curing agent is methyltetrahydrophthalic anhydride.

[0008] Preferably, the organic solvent comprises one or more of acetone, butanone, N,N-dimethylformamide, and dichloromethane. More preferably, the organic solvent is acetone.

[0009] Preferably, the inorganic filler includes one or more of silicon dioxide, calcium carbonate, calcium silicate, titanium dioxide and talc.

[0010] The present invention also provides a method for preparing a high-strength, high-toughness, high-temperature resistant epoxy resin adhesive, comprising the following steps:

[0011] (1) mixing 2-methoxy-6-methylaminopyridine and tetrahydrofuran to obtain a mixed solution, then dropping a boron trifluoride ether solution into the mixed solution, reacting at room temperature, washing and drying to obtain a 2-methoxy-6-methylaminopyridine-boron trifluoride complex;

[0012] (2) mixing an epoxy resin with an organic solvent to obtain a mixed solution A, then mixing the mixed solution A with a 2-methoxy-6-methylaminopyridine-boron trifluoride complex to obtain a mixed solution B; then mixing the mixed solution B with an inorganic filler and heating to obtain a mixed solution C;

[0013] (3) Mixing the curing agent with the mixture C to obtain a mixture D, and heating and curing the mixture to obtain a high-strength, high-toughness, and high-temperature resistant epoxy resin adhesive.

[0014] Preferably, in step (1), the mass ratio of 2-methoxy-6-methylaminopyridine to tetrahydrofuran is 1:10-20; the mass ratio of boron trifluoride ether solution to 2-methoxy-6-methylaminopyridine is 1:1-1.5.

[0015] Preferably, the mass ratio of the epoxy resin to the organic solvent in step (2) is 1:1-2; the mass ratio of the mixed solution A to the 2-methoxy-6-methylaminopyridine-boron trifluoride complex is 60-70:1; and the mass ratio of the mixed solution B to the inorganic filler is 15-20:3.

[0016] Preferably, the mixing and heating temperature in step (2) is 60-90° C. and the time is 2-6 hours.

[0017] Preferably, the mass ratio of the curing agent to the mixed liquid C in step (3) is 6-7:5.

[0018] Preferably, the heating curing temperature in step (3) is divided into three-stage step-by-step curing. In the three-stage step-by-step curing, the first stage of the curing temperature is 70-80°C, the heating rate is 3-5°C / min, and the curing time is 1-2 hours; the second stage of the curing temperature is 90-110°C, the heating rate is 3-5°C / min, and the curing time is 1-2 hours; the third stage of the curing temperature is 120-140°C, the heating rate is 3-5°C / min, and the curing time is 8-10 hours.

[0019] The present invention also provides an application of a high-strength, high-toughness, high-temperature-resistant epoxy resin adhesive in bonding materials.

[0020] Preferably, the bonding material is a cardboard sheet, and the breakage rate of the cardboard sheet is used to characterize the viscosity of the adhesive.

[0021] The epoxy resin used in the present invention is not limited, and any commercially available epoxy resin product can be used as one of the raw materials of the present invention.

[0022] Beneficial Effects

[0023] (1) The curing accelerator used in the present invention is a latent curing accelerator, which can avoid pre-curing and reduce the curing temperature.

[0024] (2) The 2-methoxy 6-methylaminopyridine-boron trifluoride complex used in the present invention can form microcapsules with epoxy resin and achieve slow release during the curing process. Boron trifluoride and epoxy resin coexist stably, and at the melting temperature of the capsule wall material, they are quickly mixed to achieve the purpose of rapid curing and shorten the curing time. It can also serve as a chemical crosslinking point and stress absorption point to effectively strengthen and toughen the epoxy resin adhesive and improve its mechanical properties.

[0025] (3) The high-strength, high-toughness, high-temperature resistant epoxy resin adhesive of the present invention has low preparation cost, high process efficiency, good modification effect, and good market application prospects. DETAILED DESCRIPTION

[0026] The present invention will be further described below in conjunction with specific embodiments. It should be understood that these embodiments are only used to illustrate the present invention and are not intended to limit the scope of the present invention. In addition, it should be understood that after reading the content taught by the present invention, those skilled in the art can make various changes or modifications to the present invention, and these equivalent forms fall within the scope limited by the appended claims of the application equally.

[0027] The preparation steps of the 2-methoxy 6-methylaminopyridine-boron trifluoride complex used in the embodiment are as follows:

[0028] ① Add 50 g of 2-methoxy-6-methylaminopyridine and 500 g of tetrahydrofuran into a reaction kettle and mix them with mechanical stirring.

[0029] ② Add boron trifluoride ether solution into the reaction kettle using a constant pressure funnel. The mass of the boron trifluoride ether solution (concentration 99.5%) is 51.5 g.

[0030] ③ After the dropwise addition was completed, the mixture was reacted at room temperature for 2 hours. After the reaction was completed, the generated solid was collected by filtration to obtain a crude 2-methoxy-6-methylaminopyridine-boron trifluoride complex.

[0031] ④ Dry in a vacuum oven at 80°C for 2 hours to obtain 2-methoxy-6-methylaminopyridine-boron trifluoride complex.

[0032] Example 1

[0033] This embodiment provides a method for preparing a high-strength, high-toughness, high-temperature resistant epoxy resin adhesive, the steps are as follows:

[0034] (1) 30 g of epoxy resin was dissolved in 30 g of acetone to obtain a mixed solution A; 0.2 g of 2-methoxy-6-methylaminopyridine-boron trifluoride ether complex was added to 60 g of the mixed solution A to obtain a mixed solution B; 14 g of calcium carbonate titanium dioxide mixed filler (mass ratio 1:1) was added to the mixed solution B, and the mixture was heated in an oven at 70° C. for 0.2 hours, and then taken out and stirred to obtain a mixed solution C; the mixed solution C was placed in an oven at 80° C. for four hours to remove the organic solvent acetone.

[0035] (2) 25 g of methyltetrahydrophthalic anhydride and mixture C were mixed and heated in an oven at 70° C. for 0.2 hours. After being taken out and stirred evenly, the mixture was heated to 80° C. at a heating rate of 3° C. / min for heating and curing for 2 hours in the first stage. The mixture was heated to 100° C. at a heating rate of 3° C. / min for heating and curing for 2 hours in the second stage. The mixture was heated to 140° C. at a heating rate of 3° C. / min for heating and curing for 8 hours in the third stage to obtain a high-strength, high-toughness, and high-temperature resistant epoxy resin adhesive.

[0036] Example 2

[0037] This embodiment provides a method for preparing a high-strength, high-toughness, high-temperature resistant epoxy resin adhesive, the steps are as follows:

[0038] (1) 30 g of epoxy resin was dissolved in 30 g of acetone to obtain a mixed solution A; 0.4 g of 2-methoxy-6-methylaminopyridine-boron trifluoride ether complex was added to 60 g of the mixed solution A to obtain a mixed solution B; 14 g of calcium carbonate titanium dioxide mixed filler (mass ratio 1:1) was added to the mixed solution B, and the mixture was heated in an oven at 70° C. for 0.2 hours, and then taken out and stirred to obtain a mixed solution C; the mixed solution C was placed in an oven at 80° C. for four hours to remove the organic solvent acetone.

[0039] (2) 25 g of methyltetrahydrophthalic anhydride and mixture C were mixed and heated in an oven at 70° C. for 0.2 hours. After being taken out and stirred evenly, the mixture was heated to 80° C. at a heating rate of 3° C. / min for heating and curing for 2 hours in the first stage. The mixture was heated to 100° C. at a heating rate of 3° C. / min for heating and curing for 2 hours in the second stage. The mixture was heated to 140° C. at a heating rate of 3° C. / min for heating and curing for 8 hours in the third stage to obtain a high-strength, high-toughness, and high-temperature resistant epoxy resin adhesive.

[0040] Example 3

[0041] This embodiment provides a method for preparing a high-strength, high-toughness, high-temperature resistant epoxy resin adhesive, the steps are as follows:

[0042] (1) 30 g of epoxy resin was dissolved in 30 g of acetone to obtain a mixed solution A; 0.6 g of 2-methoxy-6-methylaminopyridine-boron trifluoride ether complex was added to 60 g of the mixed solution A to obtain a mixed solution B; 14 g of calcium carbonate titanium dioxide mixed filler (mass ratio 1:1) was added to the mixed solution B, and the mixture was heated in an oven at 70° C. for 0.2 hours, and then taken out and stirred to obtain a mixed solution C; the mixed solution C was placed in an oven at 80° C. for four hours to remove the organic solvent acetone.

[0043] (2) 25 g of methyltetrahydrophthalic anhydride and mixture C were mixed and heated in an oven at 70° C. for 0.2 hours. After being taken out and stirred evenly, the mixture was heated to 80° C. at a heating rate of 3° C. / min for heating and curing for 2 hours in the first stage. The mixture was heated to 100° C. at a heating rate of 3° C. / min for heating and curing for 2 hours in the second stage. The mixture was heated to 140° C. at a heating rate of 3° C. / min for heating and curing for 8 hours in the third stage to obtain a high-strength, high-toughness, and high-temperature resistant epoxy resin adhesive.

[0044] Example 4

[0045] This embodiment provides a method for preparing a high-strength, high-toughness, high-temperature resistant epoxy resin adhesive, the steps are as follows:

[0046] (1) 30 g of epoxy resin was dissolved in 30 g of acetone to obtain a mixed solution A; 0.8 g of 2-methoxy-6-methylaminopyridine-boron trifluoride ether complex was added to 60 g of the mixed solution A to obtain a mixed solution B; 14 g of calcium carbonate titanium dioxide mixed filler (mass ratio 1:1) was added to the mixed solution B, and the mixture was heated in an oven at 70° C. for 0.2 hours, and then taken out and stirred to obtain a mixed solution C; the mixed solution C was placed in an oven at 80° C. for four hours to remove the organic solvent acetone.

[0047] (2) 25 g of methyltetrahydrophthalic anhydride and mixture C were mixed and heated in an oven at 70° C. for 0.2 hours. After being taken out and stirred evenly, the mixture was heated to 80° C. at a heating rate of 3° C. / min for heating and curing for 2 hours in the first stage. The mixture was heated to 100° C. at a heating rate of 3° C. / min for heating and curing for 2 hours in the second stage. The mixture was heated to 140° C. at a heating rate of 3° C. / min for heating and curing for 8 hours in the third stage to obtain a high-strength, high-toughness, and high-temperature resistant epoxy resin adhesive.

[0048] Example 5

[0049] (1) 30 g of epoxy resin was dissolved in 30 g of acetone to obtain a mixed solution A; 1.0 g of 2-methoxy-6-methylaminopyridine-boron trifluoride ether complex was added to 60 g of the mixed solution A to obtain a mixed solution B; 14 g of calcium carbonate titanium dioxide mixed filler (mass ratio 1:1) was added to the mixed solution B, and the mixture was heated in an oven at 70° C. for 0.2 hours, and then taken out and stirred to obtain a mixed solution C; the mixed solution C was placed in an oven at 80° C. for four hours to remove the organic solvent acetone.

[0050] (2) 25 g of methyltetrahydrophthalic anhydride and mixture C were mixed and heated in an oven at 70° C. for 0.2 hours. After being taken out and stirred evenly, the mixture was heated to 80° C. at a heating rate of 3° C. / min for heating and curing for 2 hours in the first stage. The mixture was heated to 100° C. at a heating rate of 3° C. / min for heating and curing for 2 hours in the second stage. The mixture was heated to 140° C. at a heating rate of 3° C. / min for heating and curing for 8 hours in the third stage to obtain a high-strength, high-toughness, and high-temperature resistant epoxy resin adhesive.

[0051] Comparative Example 1

[0052] Compared with the above examples, the difference is that no 4-methylaminopyridine-boron trifluoride complex is added.

[0053] (2) Dissolve 30 g of epoxy resin in 30 g of acetone to obtain a mixed solution A; add 14 g of calcium carbonate titanium dioxide mixed filler to the mixed solution A, heat in an oven at 70° C. for 0.2 hours, take out and stir evenly to obtain a mixed solution C; place the mixed solution C in an oven at 80° C. for four hours to remove the organic solvent acetone.

[0054] (2) 25 g of methyltetrahydrophthalic anhydride and mixture C were mixed and heated in an oven at 70° C. for 0.2 hours. After being taken out and stirred evenly, the mixture was heated to 80° C. at a heating rate of 3° C. / min for heating and curing for 2 hours in the first stage. The mixture was heated to 100° C. at a heating rate of 3° C. / min for heating and curing for 2 hours in the second stage. The mixture was heated to 140° C. at a heating rate of 3° C. / min for heating and curing for 8 hours in the third stage to obtain an epoxy resin adhesive.

[0055] The performance test method of epoxy resin adhesive is as follows:

[0056] (1) Tensile properties: The samples were measured according to GB / T 1040.2-2018.

[0057] (2) Toughness: The samples were tested according to GB / T 2567-2021, and the elongation at break of the adhesive was used to evaluate its quality.

[0058] (3) Glass transition temperature: tested using a differential scanning calorimeter. Instrument model: Netzsch DSC-214polyma. (4) Thermal weight loss: tested the sample in accordance with GB / T27761-2011 standard.

[0059] The following table shows the test results of the above epoxy resin adhesive:

[0060]

[0061]

[0062] From the above results, it can be seen that the addition of 2-methoxy 6-methylaminopyridine-boron trifluoride complex significantly improves the tensile strength and elongation at break of epoxy resin adhesive, among which the effect is more significant when the addition amount is 0.8%, and the effect shows a downward trend if it continues to be improved.

[0063] The high-strength, high-toughness, high-temperature-resistant epoxy resin adhesive of the present invention has a high glass transition temperature and a significant downward trend in thermal weight loss, indicating that the epoxy resin adhesive has good high-temperature resistance.

Claims

1. A high-strength, high-toughness, high-temperature resistant epoxy resin adhesive, characterized in that: In parts by weight, it comprises the following components: Boron complexes.

2. The high-strength, high-toughness, high-temperature-resistant epoxy resin adhesive according to claim 1, characterized in that: The preparation method of the 2-methoxy 6-methylamino pyridine-boron trifluoride complex comprises the following steps: mixing 2-methoxy 6-methylamino pyridine with tetrahydrofuran to obtain a mixed solution, then dropping a boron trifluoride ether solution into the mixed solution, reacting at room temperature, washing and drying to obtain a product.

3. The high-strength, high-toughness, high-temperature-resistant epoxy resin adhesive according to claim 1, characterized in that: The curing agent is an acid anhydride curing agent.

4. The high-strength, high-toughness, high-temperature-resistant epoxy resin adhesive according to claim 1, characterized in that: The organic solvent includes one or more of acetone, butanone, N,N-dimethylformamide and dichloromethane.

5. The high-strength, high-toughness, high-temperature-resistant epoxy resin adhesive according to claim 1, characterized in that: The inorganic filler includes one or more of silicon dioxide, calcium carbonate, calcium silicate, titanium dioxide, and talc.

6. A method for preparing the high-strength, high-toughness, high-temperature resistant epoxy resin adhesive according to any one of claims 1 to 5, comprising the following steps: (1) mixing 2-methoxy-6-methylaminopyridine and tetrahydrofuran to obtain a mixed solution, then dropping a boron trifluoride ether solution into the mixed solution, reacting at room temperature, washing and drying to obtain a 2-methoxy-6-methylaminopyridine-boron trifluoride complex; (2) mixing an epoxy resin with an organic solvent to obtain a mixed solution A, then mixing the mixed solution A with a 2-methoxy-6-methylaminopyridine-boron trifluoride complex to obtain a mixed solution B; then mixing the mixed solution B with an inorganic filler and heating to obtain a mixed solution C; (3) The curing agent is mixed with the mixture C to obtain a mixture D, and the mixture is heated and cured to obtain a high-strength, high-toughness, and high-temperature resistant epoxy resin adhesive.

7. The preparation method according to claim 6, characterized in that: The mass ratio of 2-methoxy-6-methylaminopyridine to tetrahydrofuran in step (1) is 1:10-20; the mass ratio of boron trifluoride ether solution to 2-methoxy-6-methylaminopyridine is 1:1-1.

5.

8. The preparation method according to claim 6, characterized in that: The mass ratio of the epoxy resin to the organic solvent in step (2) is 1:1-2; the mass ratio of the mixed solution A to the 2-methoxy-6-methylaminopyridine-boron trifluoride complex is 60-70:1; and the mass ratio of the mixed solution B to the inorganic filler is 15-20:

3.

9. The preparation method according to claim 6, characterized in that: The mass ratio of the curing agent to the mixed liquid C in the step (3) is 6-7:

5.

10. Use of the high-strength, high-toughness, high-temperature-resistant epoxy resin adhesive as claimed in any one of claims 1 to 5 in bonding materials.

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