Preparation method and application of high heat-resistant epoxy adhesive

Abstract

This invention discloses a method for preparing a high-heat-resistant epoxy adhesive and its application. By introducing rigid benzene and azinyl ring groups into epoxy resin, the heat resistance of glycidylamine-type epoxy resin is improved. Replacing glycidyl ether with glycidylamine allows the introduction of multiple epoxy groups into a single epoxy resin monomer, increasing the crosslinking density and thus improving the curing speed and high-temperature resistance of the epoxy resin. Simultaneously, the thermal stability of tertiary amine groups is higher than that of ether bonds, which also contributes to improving thermal stability. The epoxy adhesive prepared by this invention exhibits excellent high-temperature resistance, significantly expanding its application range and application scenarios.

Description

Technical Field

[0001] This invention belongs to the field of adhesive preparation technology, specifically relating to a method for preparing and applying a high heat-resistant epoxy adhesive. Background Technology

[0002] Epoxy adhesives are among the most widely used and relatively inexpensive adhesives on the market, primarily functioning to bond two objects together. They offer numerous advantages, including fast curing speed, low shrinkage, good corrosion resistance, convenient application, and low cost, making them widely used in engineering, construction, manufacturing, arts and crafts, and furniture making. Epoxy adhesives not only possess adhesive properties, firmly bonding objects together and increasing material strength and stability, but they also fill voids, level uneven surfaces, reinforce structures, and prevent material separation. However, compared to other thermosetting adhesives such as phenolic resins, epoxy adhesives generally suffer from poor heat resistance, significantly limiting their application areas.

[0003] Glycidyl amine type epoxy resin is a resin containing glycidyl amine and epoxy groups in its molecule. Due to its high crosslinking density and the high stability of the tertiary amine, this type of epoxy resin has higher heat resistance than commonly used glycidyl ether type resins, and is widely used in high-temperature adhesives, high-temperature coatings, and high-temperature advanced composite materials. However, the heat resistance of epoxy resin is also affected by the flexibility of its molecular chains. Greater molecular chain flexibility leads to more pronounced intramolecular movement, making it easier for the molecular conformation to change, thus altering the macroscopic structure of the resin. At high temperatures, the flexible molecular chains in epoxy resin affect the overall heat resistance of the resin.

[0004] The epoxy resin provided by this invention replaces the flexible molecular chain structure in the main chain with a rigid structure containing rings, while giving it a high crosslinking density, further improving the heat resistance of glycidylamine type epoxy resin, and improving the adhesive layer strength of the adhesive, thus giving epoxy resin a wider range of applications. Summary of the Invention

[0005] In view of the problems existing in the prior art, the purpose of this invention is to improve the high temperature resistance of epoxy resin adhesives, prevent the adhesives from undergoing thermal degradation in high temperature environments, reduce the strength of the adhesive layer, and further expand the application range of epoxy resins.

[0006] This invention synthesizes a novel glycidylamine-type epoxy resin adhesive with a chain-like structure. First, in the resin structure, rigid groups are more stable than flexible long chains; therefore, introducing rigid benzene and azinyl ring groups into the epoxy resin can improve its heat resistance. Second, replacing glycidyl ether with glycidylamine introduces multiple epoxy groups into a single epoxy resin monomer, increasing the crosslinking density and thus improving the curing speed and high-temperature resistance of the epoxy resin. Finally, the thermal stability of tertiary amine groups is higher than that of ether bonds, which also contributes to improving thermal stability. In summary, the epoxy adhesive provided by this invention exhibits excellent high-temperature resistance, significantly expanding its application range and application scenarios.

[0007] This invention is specifically implemented through the following technical solutions:

[0008] Step 1): Dissolve p-bromoaniline and p-methoxybenzyl chloride separately in N,N-dimethylformamide (DMF). Add the p-bromoaniline-DMF solution to a three-necked flask, and add the methoxybenzyl chloride-DMF mixed solution to a constant-pressure dropping funnel. Add triethylamine to the flask, heat, stir, and react at a certain temperature for a certain time. After cooling, remove the crystals, wash with water, and dry to obtain 4-bromo-N,N-bis(4-methoxybenzyl)aniline (BMBA).

[0009] Preferably, in step 1), the molar ratio of p-bromoaniline to DMF is 1:90-1:130, the volume ratio of p-methoxybenzyl chloride to DMF is 1:5-1:15, and the molar ratio of p-bromoaniline, p-methoxybenzyl chloride, and triethylamine is 1:2:2-1:2.2:2.2. The rotor stirring speed is 200-500 rpm, the reaction temperature is 75-85℃, and the reaction time is 3-4 h. The volume ratio of water to DMF is 1:0.9-1:1.1, and the product is washed 2-3 times. The obtained product is dried at 75-85℃ for 1-2 h. Most preferably, the molar ratio of p-bromoaniline to DMF is 1:110, the volume ratio of p-methoxybenzyl chloride to DMF is 1:10, the molar ratio of p-bromoaniline, p-methoxybenzyl chloride, and triethylamine is 1:2.1:2.1, the rotor stirring speed is 400 rpm, the reaction temperature is 80℃, and the reaction time is 3.5 h. The water to DMF volume ratio was 1:1, and the product was washed three times. The obtained product was dried at 80°C for 1.5 hours.

[0010] Step 2): The BMBA prepared in Step 1) is dried and dehydrated, then added to tetrahydrofuran containing molecular sieves, along with magnesium shavings and elemental iodine. The reaction solution is deoxygenated and heated under nitrogen protection until no more bubbles emerge from the solution, yielding (4-(bis(4-methoxybenzyl)amino)phenyl)magnesium bromide (Grignard reagent).

[0011] Preferably, in step 2), the molar ratio of BMBA to Mg is in the range of 1:1-1:1.4, the molar ratio of BMBA to THF is in the range of 1:10-1:15, and the molar ratio of added iodine to BMBA is 1:20-1:30. The stirring rate is 300-400 rpm, the temperature is 30-40°C, and the reaction is carried out for 4-5 hours. Most preferably, the molar ratio of BMBA to Mg is 1:1.2, the molar ratio of BMBA to THF is 1:12, and the molar ratio of added iodine to BMBA is 1:25. The stirring rate is 350 rpm, the temperature is 35°C, and the reaction is carried out for 4 hours.

[0012] Step 3): Dissolve cyanuric chloride (TCT) in THF, heat it, add the Grignard reagent synthesized in step (2) dropwise, stir the reaction for a period of time, and obtain 4,4',4”-(1,3,5-triazine-2,4,6-triyl)tris(N,N-bis(4-methoxybenzyl)aniline)(TTMA).

[0013] Preferably, in step 3), the molar ratio of TCT to THF is in the range of 1:50-1:70, the reaction temperature is 75-85℃, and the rotor stirring speed is 300-500 rpm. The molar ratio of TCT to the Grignard reagent synthesized in step 2) is in the range of 1:3-1:3.2, the dropping rate is 10-15 drops / min, and the reaction time is 7-9 h. Optimally, the molar ratio of TCT to THF is 1:60, the reaction temperature is 80℃, the rotor stirring speed is 400 rpm, the molar ratio of TCT to the Grignard reagent synthesized in step 2) is 1:3.1, the dropping rate is 13 drops / min, and the reaction time is 8 h.

[0014] Step 4): Dissolve the TTMA obtained in step 3) in dichloromethane (DCM), add trifluoroacetic acid (TFA) dropwise to react, and after reacting for a period of time, wash the solution with saturated sodium bicarbonate aqueous solution, titrate the pH to neutral, and separate and extract 4,4',4”-(1,3,5-triazine-2,4,6-triyl)triphenylamine (TTA).

[0015] Preferably, in step 4), the molar ratio of TTMA to DCM is 1:500-1:700, the molar ratio of TTMA to TFA is 1:6-1:9, the reaction temperature is 0-50℃, the rotor speed is 300-500 rpm, and the reaction time is 6-10 h. The solution pH range is 6.9-7.1. Most preferably, the molar ratio of TTMA to DCM is 1:600, the molar ratio of TTMA to TFA is 1:8, the reaction temperature is 40℃, the rotor speed is 400 rpm, and the reaction time is 8 h. The pH is adjusted to 7.

[0016] Step 5): Add the TTA prepared in Step 4) to epichlorohydrin and react in a three-necked flask. Add tetrabutylammonium bromide (TBAB) and stir the reaction at a certain temperature to obtain a mixture of chlorohydrin ethers.

[0017] Preferably, in step 5), the molar ratio of TTA to epichlorohydrin is 1:36-1:80. The mass ratio of TTA to TBAB is 1:1-1:1.6. The reaction system temperature is 70-100℃, the stirring speed is 200-350 rpm, and the reaction time is 2.5-4 h. Optimally, the molar ratio of TTA to epichlorohydrin is 1:55, the mass ratio of TTA to TBAB is 1:1.3, the reaction temperature is 80℃, the stirring speed is 300 rpm, and the reaction time is 3 h.

[0018] Step 6) Add the sodium hydroxide aqueous solution to the chlorohydrin ether mixture in Step 5), cool and react for a period of time, stir, filter, extract, remove solvent by rotary evaporation, wash, dry, and obtain epoxy adhesive resin 4,4',4”-(1,3,5-triazine-2,4,6-triyl)tris(N,N-bis(ethylene oxide-2-ylmethyl)aniline) (TTOYA).

[0019] Preferably, in step 6), the concentration (mass fraction) of the NaOH aqueous solution is 30%-70%. The volume ratio of the NaOH solution to the chlorohydrin ether mixture is 1:20-1:30. The reaction temperature is 50-70℃, the reaction time is 2.5-4h, and the stirring speed is 200-350rpm. Most preferably, the volume ratio of NaOH solution to chlorohydrin ether is 1:25, the concentration (mass fraction) of the NaOH aqueous solution is 50%, the reaction temperature is 60℃, the reaction time is 3h, and the stirring speed is 300rpm.

[0020] Preferably, in step 6), the detergent is a mixture of deionized water and epichlorohydrin in a volume ratio of 1:0.8-1:2. The extraction solvent is toluene, and the volume of toluene added is 0.2-0.4 times the volume of the filtrate. The mixture is then washed 3-5 times with 2-4 times the volume of toluene in deionized water. Most preferably, the volume ratio of deionized water to epichlorohydrin is 1:1, the volume ratio of toluene to filtrate is 1:3, the volume ratio of deionized water to toluene used for washing is 1:3, and the washing is performed 4 times.

[0021] Preferably, in the rotary evaporation solvent removal step of 6), the extracted organic phase is dried using a rotary evaporator with a vacuum degree ranging from 0.08 to -0.1 MPa, a rotary evaporation temperature of 40-60°C, and a rotary drying time of 20-50 min. Most preferably, the vacuum degree is -0.1 MPa, and the drying time is 30 min at 50°C.

[0022] The application of the binder prepared by the above method in brake pad binders.

[0023] The advantages of the present invention are:

[0024] 1) Based on traditional epoxy resin, the most widely used glycidyl ether type epoxy resin is replaced with glycidyl amine type epoxy resin, so that the ether bond is replaced with the tertiary amine bond, which improves the structural stability of the crosslinking site of the group.

[0025] 2) By replacing flexible chains with rigid chains in the resin matrix and introducing rigid groups such as benzene rings and azinium rings, the heat resistance of the resin is further improved.

[0026] 3) The amino group links two epoxy groups, which greatly increases the crosslinking sites, thereby increasing the crosslinking density after the resin is cured and improving the bonding strength and heat resistance of the epoxy resin. Attached Figure Description

[0027] Figure 1 The steps for synthesizing 4-bromo-N,N-bis(4-methoxybenzyl)aniline;

[0028] Figure 2 The synthetic steps for (4-(bis(4-methoxybenzyl)amino)phenyl)magnesium bromide;

[0029] Figure 3 The synthetic steps for 4,4',4”-(1,3,5-triazine-2,4,6-triyl)tris(N,N-bis(4-methoxybenzyl)aniline);

[0030] Figure 4 The steps for synthesizing 4,4',4”-(1,3,5-triazine-2,4,6-triyl)triphenylamine;

[0031] Figure 5 The steps for synthesizing chlorohydrin ethers of TTA resin;

[0032] Figure 6 The synthetic steps for 4,4',4”-(1,3,5-triazine-2,4,6-triyl)tris(N,N-bis(ethylene oxide-2-ylmethyl)aniline). Detailed Implementation

[0033] The present invention will be further described below with reference to specific embodiments in order to better understand the technical solution.

[0034] In the following examples, the synthesis steps of 4-bromo-N,N-bis(4-methoxybenzyl)aniline are as follows: Figure 1 As shown, the synthetic steps of (4-(bis(4-methoxybenzyl)amino)phenyl)magnesium bromide are as follows: Figure 2 As shown, the synthetic steps of 4,4',4”-(1,3,5-triazine-2,4,6-triyl)tris(N,N-bis(4-methoxybenzyl)aniline) are as follows: Figure 3 As shown, the synthetic steps of 4,4',4”-(1,3,5-triazine-2,4,6-triyl)triphenylamine are as follows: Figure 4 As shown, the synthesis steps of the chlorohydrin ether of TTA resin are as follows: Figure 5 As shown, the synthetic steps of 4,4',4”-(1,3,5-triazine-2,4,6-triyl)tris(N,N-bis(ethylene oxide-2-ylmethyl)aniline) are as follows: Figure 6 As shown.

[0035] Example 1

[0036] Step 1): Dissolve 0.020 mol of p-bromoaniline and 0.042 mol of p-methoxybenzyl chloride in 160 mL and 54 mL of N,N-dimethylformamide (DMF), respectively. Add the p-bromoaniline-DMF mixed solution to a three-necked flask, and the p-methoxybenzyl chloride-DMF mixed solution to a constant pressure dropping funnel. Add 0.042 mol of triethylamine to the flask as an acid-binding agent, raise the temperature, and react at 80 °C for 3.5 h. After cooling, remove the crystals, add 210 mL of water to wash the product, and repeat 3 times. Dry the obtained product at 80 °C for 1.5 h to obtain 4-bromo-N,N-bis(4-methoxybenzyl)aniline (BMBA).

[0037] Step 2): Dry all experimental instruments. After drying and dehydrating the 4-bromo-N,N-bis(4-methoxybenzyl)aniline prepared in Step 1), add 0.020 mol of BMBA to 19.5 mL of tetrahydrofuran that has passed through a molecular sieve, then add 0.024 mol of polished magnesium shavings, followed by two grains of elemental iodine. Deoxygenate the entire reaction system and protect it with nitrogen. Heat to 35°C and react until the solution stabilizes and no more bubbles emerge, yielding (4-(bis(4-methoxybenzyl)amino)phenyl)magnesium bromide (Grignard reagent).

[0038] Step 3): Dissolve 0.006 mol of cyanuric chloride (TCT) in 29 mL of THF, then heat to 80 °C, and add 0.019 mol of Grignard reagent synthesized in Step 2) dropwise at a dropping rate of 13 drops / min. After stirring for 8 h, 4,4',4”-(1,3,5-triazine-2,4,6-triyl)tris(N,N-bis(4-methoxybenzyl)aniline) (TTMA) is obtained.

[0039] Step 4): Dissolve 0.006 mol TTMA from step 3) in 38.5 mL of dichloromethane (DCM), then add 0.048 mol trifluoroacetic acid (TFA) dropwise to react. React at 40 °C for 8 h. Then quench and wash the solution with saturated sodium bicarbonate aqueous solution, titrate to pH = 7, and separate and extract to obtain 4,4',4”-(1,3,5-triazine-2,4,6-triyl)triphenylamine (TTA).

[0040] Step 5): Add 0.006 mol of TTA prepared in Step 4) to 0.33 mol of epichlorohydrin, and then transfer the mixture to a three-necked flask for reaction. Add 0.0096 mol of tetrabutylammonium bromide (TBAB) to the mixed solution and react at 80 °C for 3 h to obtain the chlorohydrin ether of TTA resin.

[0041] Step 6): Add 9 mL of 30 wt% sodium hydroxide aqueous solution to the chlorohydrin ether mixture in Step 5), cool to 60 °C and react for 3 h, extract with 30 mL of toluene, wash three times with 50 mL of deionized water, and dry to finally obtain epoxy adhesive resin 4,4',4”-(1,3,5-triazine-2,4,6-triyl)tris(N,N-bis(ethylene oxide-2-ylmethyl)aniline) (TTOYA).

[0042] Application: 0.50g of TTOYA prepared in this example was mixed with 4.50g of bisphenol A diglycidyl ether with an epoxy value of 0.51mol / 100g until homogeneous. Then, 2.50g of diethylenetriamine was added as a curing agent, and the mixture was further mixed to prepare an adhesive. The adhesive was then used for bonding tests.

[0043] Example 2

[0044] Step 1): Dissolve 0.020 mol of p-bromoaniline and 0.042 mol of p-methoxybenzyl chloride in 160 mL and 54 mL of N,N-dimethylformamide (DMF), respectively. Add the p-bromoaniline-DMF mixed solution to a three-necked flask, and the p-methoxybenzyl chloride-DMF mixed solution to a constant pressure dropping funnel. Add 0.042 mol of triethylamine to the flask as an acid-binding agent, raise the temperature, and react at 80 °C for 3.5 h. After cooling, remove the crystals, add 210 mL of water to wash the product, and repeat 3 times. Dry the obtained product at 80 °C for 1.5 h to obtain 4-bromo-N,N-bis(4-methoxybenzyl)aniline (BMBA).

[0045] Step 2): Dry all experimental instruments. After drying and dehydrating the 4-bromo-N,N-bis(4-methoxybenzyl)aniline prepared in Step 1), add 0.020 mol of BMBA to 19.5 mL of tetrahydrofuran that has passed through a molecular sieve, then add 0.024 mol of polished magnesium shavings, followed by two grains of elemental iodine. Deoxygenate the entire reaction system and protect it with nitrogen. Heat to 35°C and react until the solution stabilizes and no more bubbles emerge, yielding (4-(bis(4-methoxybenzyl)amino)phenyl)magnesium bromide (Grignard reagent).

[0046] Step 3): Dissolve 0.006 mol of cyanuric chloride (TCT) in 29 mL of THF, then heat to 80 °C, and add 0.019 mol of Grignard reagent synthesized in Step 2) dropwise at a dropping rate of 13 drops / min. After stirring for 8 h, 4,4',4”-(1,3,5-triazine-2,4,6-triyl)tris(N,N-bis(4-methoxybenzyl)aniline) (TTMA) is obtained.

[0047] Step 4): Dissolve 0.006 mol TTMA from step 3) in 38.5 mL of dichloromethane (DCM), then add 0.048 mol trifluoroacetic acid (TFA) dropwise to react. React at 40 °C for 8 h. Then quench and wash the solution with saturated sodium bicarbonate aqueous solution, titrate to pH = 7, and separate and extract to obtain 4,4',4”-(1,3,5-triazine-2,4,6-triyl)triphenylamine (TTA).

[0048] Step 5): Add 0.006 mol of TTA prepared in Step 4) to 0.33 mol of epichlorohydrin, and then transfer the mixture to a three-necked flask for reaction. Add 0.0096 mol of tetrabutylammonium bromide (TBAB) to the mixed solution and react at 80 °C for 3 h to obtain the chlorohydrin ether of TTA resin.

[0049] Step 6): Add 9 mL of 30 wt% sodium hydroxide aqueous solution to the chlorohydrin ether mixture in Step 5), cool to 60 °C and react for 3 h, extract with 30 mL of toluene, wash three times with 50 mL of deionized water, and dry to finally obtain epoxy adhesive resin 4,4',4”-(1,3,5-triazine-2,4,6-triyl)tris(N,N-bis(ethylene oxide-2-ylmethyl)aniline) (TTOYA).

[0050] Application: 1.00g of TTOYA prepared in this example was mixed with 4.00g of bisphenol A diglycidyl ether with an epoxy value of 0.51mol / 100g until homogeneous. Then, 2.50g of diethylenetriamine was added as a curing agent, and the mixture was further mixed to prepare an adhesive. The adhesive was then used for bonding tests.

[0051] Example 3

[0052] Step 1): Dissolve 0.020 mol of p-bromoaniline and 0.042 mol of p-methoxybenzyl chloride in 160 mL and 54 mL of N,N-dimethylformamide (DMF), respectively. Add the p-bromoaniline-DMF mixed solution to a three-necked flask, and the p-methoxybenzyl chloride-DMF mixed solution to a constant pressure dropping funnel. Add 0.042 mol of triethylamine to the flask as an acid-binding agent, raise the temperature, and react at 80 °C for 3.5 h. After cooling, remove the crystals, add 210 mL of water to wash the product, and repeat 3 times. Dry the obtained product at 80 °C for 1.5 h to obtain 4-bromo-N,N-bis(4-methoxybenzyl)aniline (BMBA).

[0053] Step 2): Dry all experimental instruments. After drying and dehydrating the 4-bromo-N,N-bis(4-methoxybenzyl)aniline prepared in Step 1), add 0.020 mol of BMBA to 19.5 mL of tetrahydrofuran that has passed through a molecular sieve, then add 0.024 mol of polished magnesium shavings, followed by two grains of elemental iodine. Deoxygenate the entire reaction system and protect it with nitrogen. Heat to 35°C and react until the solution stabilizes and no more bubbles emerge, yielding (4-(bis(4-methoxybenzyl)amino)phenyl)magnesium bromide (Grignard reagent).

[0054] Step 3): Dissolve 0.006 mol of cyanuric chloride (TCT) in 29 mL of THF, then heat to 80 °C, and add 0.019 mol of Grignard reagent synthesized in Step 2) dropwise at a dropping rate of 13 drops / min. After stirring for 8 h, 4,4',4”-(1,3,5-triazine-2,4,6-triyl)tris(N,N-bis(4-methoxybenzyl)aniline) (TTMA) is obtained.

[0055] Step 4): Dissolve 0.006 mol TTMA from step 3) in 38.5 mL of dichloromethane (DCM), then add 0.048 mol trifluoroacetic acid (TFA) dropwise to react. React at 40 °C for 8 h. Then quench and wash the solution with saturated sodium bicarbonate aqueous solution, titrate to pH = 7, and separate and extract to obtain 4,4',4”-(1,3,5-triazine-2,4,6-triyl)triphenylamine (TTA).

[0056] Step 5): Add 0.006 mol of TTA prepared in Step 4) to 0.33 mol of epichlorohydrin, and then transfer the mixture to a three-necked flask for reaction. Add 0.0096 mol of tetrabutylammonium bromide (TBAB) to the mixed solution and react at 80 °C for 3 h to obtain the chlorohydrin ether of TTA resin.

[0057] Step 6): Add 9 mL of 30 wt% sodium hydroxide aqueous solution to the chlorohydrin ether mixture in step (5), cool to 60 °C and react for 3 h, extract with 30 mL of toluene, wash 3 times with 50 mL of deionized water, dry, and finally obtain epoxy adhesive resin 4,4',4”-(1,3,5-triazine-2,4,6-triyl)tris(N,N-bis(ethylene oxide-2-ylmethyl)aniline) (TTOYA).

[0058] Application: 1.50g of TTOYA and 3.50g of bisphenol A diglycidyl ether with an epoxy value of 0.51mol / 100g, prepared in this example, were mixed evenly, and then 2.50g of diethylenetriamine was added as a curing agent to prepare an adhesive. The adhesive was then used for bonding tests.

[0059] Example 4

[0060] Step 1): Dissolve 0.020 mol of p-bromoaniline and 0.042 mol of p-methoxybenzyl chloride in 160 mL and 54 mL of N,N-dimethylformamide (DMF), respectively. Add the p-bromoaniline-DMF mixed solution to a three-necked flask, and the p-methoxybenzyl chloride-DMF mixed solution to a constant pressure dropping funnel. Add 0.042 mol of triethylamine to the flask as an acid-binding agent, raise the temperature, and react at 80 °C for 3.5 h. After cooling, remove the crystals, add 210 mL of water to wash the product, and repeat 3 times. Dry the obtained product at 80 °C for 1.5 h to obtain 4-bromo-N,N-bis(4-methoxybenzyl)aniline (BMBA).

[0061] Step 2): Dry all experimental instruments. After drying and dehydrating the 4-bromo-N,N-bis(4-methoxybenzyl)aniline prepared in Step 1), add 0.020 mol of BMBA to 19.5 mL of tetrahydrofuran that has passed through a molecular sieve, then add 0.024 mol of polished magnesium shavings, followed by two grains of elemental iodine. Deoxygenate the entire reaction system and protect it with nitrogen. Heat to 35°C and react until the solution stabilizes and no more bubbles emerge, yielding (4-(bis(4-methoxybenzyl)amino)phenyl)magnesium bromide (Grignard reagent).

[0062] Step 3): Dissolve 0.006 mol of cyanuric chloride (TCT) in 29 mL of THF, then heat to 80 °C, and add 0.019 mol of Grignard reagent synthesized in Step 2) dropwise at a dropping rate of 13 drops / min. After stirring for 8 h, 4,4',4”-(1,3,5-triazine-2,4,6-triyl)tris(N,N-bis(4-methoxybenzyl)aniline) (TTMA) is obtained.

[0063] Step 4): Dissolve 0.006 mol TTMA from step 3) in 38.5 mL of dichloromethane (DCM), then add 0.048 mol trifluoroacetic acid (TFA) dropwise to react. React at 40 °C for 8 h. Then quench and wash the solution with saturated sodium bicarbonate aqueous solution, titrate to pH = 7, and separate and extract to obtain 4,4',4”-(1,3,5-triazine-2,4,6-triyl)triphenylamine (TTA).

[0064] Step 5): Add 0.006 mol of TTA prepared in Step 4) to 0.33 mol of epichlorohydrin, and then transfer the mixture to a three-necked flask for reaction. Add 0.0096 mol of tetrabutylammonium bromide (TBAB) to the mixed solution and react at 80 °C for 3 h to obtain the chlorohydrin ether of TTA resin.

[0065] Step 6): Add 9 mL of 30 wt% sodium hydroxide aqueous solution to the chlorohydrin ether mixture in Step 5), cool to 60 °C and react for 3 h, extract with 30 mL of toluene, wash three times with 50 mL of deionized water, and dry to finally obtain epoxy adhesive resin 4,4',4”-(1,3,5-triazine-2,4,6-triyl)tris(N,N-bis(ethylene oxide-2-ylmethyl)aniline) (TTOYA).

[0066] Application: 2.00g of TTOYA prepared in this example was mixed evenly with 3.00g of bisphenol A diglycidyl ether with an epoxy value of 0.51mol / 100g. Then, 2.50g of diethylenetriamine was added as a curing agent, and the mixture was mixed to prepare an adhesive. The adhesive was then used for bonding tests.

[0067] Example 5

[0068] Step 1): Dissolve 0.020 mol of p-bromoaniline and 0.042 mol of p-methoxybenzyl chloride in 160 mL and 54 mL of N,N-dimethylformamide (DMF), respectively. Add the p-bromoaniline-DMF mixed solution to a three-necked flask, and the p-methoxybenzyl chloride-DMF mixed solution to a constant pressure dropping funnel. Add 0.042 mol of triethylamine to the flask as an acid-binding agent, raise the temperature, and react at 80 °C for 3.5 h. After cooling, remove the crystals, add 210 mL of water to wash the product, and repeat 3 times. Dry the obtained product at 80 °C for 1.5 h to obtain 4-bromo-N,N-bis(4-methoxybenzyl)aniline (BMBA).

[0069] Step 2): Dry all experimental instruments. After drying and dehydrating the 4-bromo-N,N-bis(4-methoxybenzyl)aniline prepared in Step 1), add 0.020 mol of BMBA to 19.5 mL of tetrahydrofuran that has passed through a molecular sieve, then add 0.024 mol of polished magnesium shavings, followed by two grains of elemental iodine. Deoxygenate the entire reaction system and protect it with nitrogen. Heat to 35°C and react until the solution stabilizes and no more bubbles emerge, yielding (4-(bis(4-methoxybenzyl)amino)phenyl)magnesium bromide (Grignard reagent).

[0070] Step 3): Dissolve 0.006 mol of cyanuric chloride (TCT) in 29 mL of THF, then heat to 80 °C, and add 0.019 mol of Grignard reagent synthesized in Step 2) dropwise at a dropping rate of 13 drops / min. After stirring for 8 h, 4,4',4”-(1,3,5-triazine-2,4,6-triyl)tris(N,N-bis(4-methoxybenzyl)aniline) (TTMA) is obtained.

[0071] Step 4): Dissolve 0.006 mol TTMA from step 3) in 38.5 mL of dichloromethane (DCM), then add 0.048 mol trifluoroacetic acid (TFA) dropwise to react. React at 40 °C for 8 h. Then quench and wash the solution with saturated sodium bicarbonate aqueous solution, titrate to pH = 7, and separate and extract to obtain 4,4',4”-(1,3,5-triazine-2,4,6-triyl)triphenylamine (TTA).

[0072] Step 5): Add 0.006 mol of TTA prepared in Step 4) to 0.33 mol of epichlorohydrin, and then transfer the mixture to a three-necked flask for reaction. Add 0.0096 mol of tetrabutylammonium bromide (TBAB) to the mixed solution and react at 80 °C for 3 h to obtain the chlorohydrin ether of TTA resin.

[0073] Step 6): Add 9 mL of 30 wt% sodium hydroxide aqueous solution to the chlorohydrin ether mixture in Step 5), cool to 60 °C and react for 3 h, extract with 30 mL of toluene, wash three times with 50 mL of deionized water, and dry to finally obtain epoxy adhesive resin 4,4',4”-(1,3,5-triazine-2,4,6-triyl)tris(N,N-bis(ethylene oxide-2-ylmethyl)aniline) (TTOYA).

[0074] Application: 2.50g of TTOYA prepared in this example was mixed evenly with 2.50g of bisphenol A diglycidyl ether with an epoxy value of 0.51mol / 100g. Then, 2.50g of diethylenetriamine was added as a curing agent, and the mixture was further mixed to prepare an adhesive. The adhesive was then used for bonding tests.

[0075] Example 6

[0076] Step 1): Dissolve 0.020 mol of p-bromoaniline and 0.042 mol of p-methoxybenzyl chloride in 160 mL and 54 mL of N,N-dimethylformamide (DMF), respectively. Add the p-bromoaniline-DMF mixed solution to a three-necked flask, and the p-methoxybenzyl chloride-DMF mixed solution to a constant pressure dropping funnel. Add 0.042 mol of triethylamine to the flask as an acid-binding agent, raise the temperature, and react at 80 °C for 3.5 h. After cooling, remove the crystals, add 210 mL of water to wash the product, and repeat 3 times. Dry the obtained product at 80 °C for 1.5 h to obtain 4-bromo-N,N-bis(4-methoxybenzyl)aniline (BMBA).

[0077] Step 2): Dry all experimental instruments. After drying and dehydrating the 4-bromo-N,N-bis(4-methoxybenzyl)aniline prepared in Step 1), add 0.020 mol of BMBA to 19.5 mL of tetrahydrofuran that has passed through a molecular sieve, then add 0.024 mol of polished magnesium shavings, followed by two grains of elemental iodine. Deoxygenate the entire reaction system and protect it with nitrogen. Heat to 35°C and react until the solution stabilizes and no more bubbles emerge, yielding (4-(bis(4-methoxybenzyl)amino)phenyl)magnesium bromide (Grignard reagent).

[0078] Step 3): Dissolve 0.006 mol of cyanuric chloride (TCT) in 29 mL of THF, then heat to 80 °C, and add 0.019 mol of Grignard reagent synthesized in Step 2) dropwise at a dropping rate of 13 drops / min. After stirring for 8 h, 4,4',4”-(1,3,5-triazine-2,4,6-triyl)tris(N,N-bis(4-methoxybenzyl)aniline) (TTMA) is obtained.

[0079] Step 4): Dissolve 0.006 mol TTMA from step 3) in 38.5 mL of dichloromethane (DCM), then add 0.048 mol trifluoroacetic acid (TFA) dropwise to react. React at 40 °C for 8 h. Then quench and wash the solution with saturated sodium bicarbonate aqueous solution, titrate to pH = 7, and separate and extract to obtain 4,4',4”-(1,3,5-triazine-2,4,6-triyl)triphenylamine (TTA).

[0080] Step 5): Add 0.006 mol of TTA prepared in Step 4) to 0.33 mol of epichlorohydrin, and then transfer the mixture to a three-necked flask for reaction. Add 0.0096 mol of tetrabutylammonium bromide (TBAB) to the mixed solution and react at 80 °C for 3 h to obtain the chlorohydrin ether of TTA resin.

[0081] Step 6): Add 9 mL of 30 wt% sodium hydroxide aqueous solution to the chlorohydrin ether mixture in Step 5), cool to 60 °C and react for 3 h, extract with 30 mL of toluene, wash three times with 50 mL of deionized water, and dry to finally obtain epoxy adhesive resin 4,4',4”-(1,3,5-triazine-2,4,6-triyl)tris(N,N-bis(ethylene oxide-2-ylmethyl)aniline) (TTOYA).

[0082] Application: 3.00g of TTOYA prepared in this example was mixed evenly with 2.00g of bisphenol A diglycidyl ether with an epoxy value of 0.51mol / 100g. Then, 2.50g of diethylenetriamine was added as a curing agent, and the mixture was mixed to prepare an adhesive. The adhesive was then used for bonding tests.

[0083] Example 7

[0084] Step 1): Dissolve 0.020 mol of p-bromoaniline and 0.042 mol of p-methoxybenzyl chloride in 160 mL and 54 mL of N,N-dimethylformamide (DMF), respectively. Add the p-bromoaniline-DMF mixed solution to a three-necked flask, and the p-methoxybenzyl chloride-DMF mixed solution to a constant pressure dropping funnel. Add 0.042 mol of triethylamine to the flask as an acid-binding agent, raise the temperature, and react at 80 °C for 3.5 h. After cooling, remove the crystals, add 210 mL of water to wash the product, and repeat 3 times. Dry the obtained product at 80 °C for 1.5 h to obtain 4-bromo-N,N-bis(4-methoxybenzyl)aniline (BMBA).

[0085] Step 2): Dry all experimental instruments. After drying and dehydrating the 4-bromo-N,N-bis(4-methoxybenzyl)aniline prepared in Step 1), add 0.020 mol of BMBA to 19.5 mL of tetrahydrofuran that has passed through a molecular sieve, then add 0.024 mol of polished magnesium shavings, followed by two grains of elemental iodine. Deoxygenate the entire reaction system and protect it with nitrogen. Heat to 35°C and react until the solution stabilizes and no more bubbles emerge, yielding (4-(bis(4-methoxybenzyl)amino)phenyl)magnesium bromide (Grignard reagent).

[0086] Step 3): Dissolve 0.006 mol of cyanuric chloride (TCT) in 29 mL of THF, then heat to 80 °C, and add 0.019 mol of Grignard reagent synthesized in Step 2) dropwise at a dropping rate of 13 drops / min. After stirring for 8 h, 4,4',4”-(1,3,5-triazine-2,4,6-triyl)tris(N,N-bis(4-methoxybenzyl)aniline) (TTMA) is obtained.

[0087] Step 4): Dissolve 0.006 mol TTMA from step 3) in 38.5 mL of dichloromethane (DCM), then add 0.048 mol trifluoroacetic acid (TFA) dropwise to react. React at 40 °C for 8 h. Then quench and wash the solution with saturated sodium bicarbonate aqueous solution, titrate to pH = 7, and separate and extract to obtain 4,4',4”-(1,3,5-triazine-2,4,6-triyl)triphenylamine (TTA).

[0088] Step 5): Add 0.006 mol of TTA prepared in Step 4) to 0.33 mol of epichlorohydrin, and then transfer the mixture to a three-necked flask for reaction. Add 0.0096 mol of tetrabutylammonium bromide (TBAB) to the mixed solution and react at 80 °C for 3 h to obtain the chlorohydrin ether of TTA resin.

[0089] Step 6): Add 9 mL of 30 wt% sodium hydroxide aqueous solution to the chlorohydrin ether mixture in Step 5), cool to 60 °C and react for 3 h, extract with 30 mL of toluene, wash three times with 50 mL of deionized water, and dry to finally obtain epoxy adhesive resin 4,4',4”-(1,3,5-triazine-2,4,6-triyl)tris(N,N-bis(ethylene oxide-2-ylmethyl)aniline) (TTOYA).

[0090] Application: Mix 3.50g of TTOYA and 1.50g of bisphenol A diglycidyl ether with an epoxy value of 0.51mol / 100g until homogeneous, then add 2.50g of diethylenetriamine as a curing agent to prepare an adhesive. The adhesive was then used for bonding tests.

[0091] Comparative Example 1

[0092] 5.00g of TTOYA and 2.50g of diethylenetriamine were mixed evenly to prepare an adhesive. The adhesive was then used for bonding tests.

[0093] Comparative Example 2

[0094] A binder was prepared by mixing 5.00 g of bisphenol A diglycidyl ether with an epoxy value of 0.51 mol / 100 g with 2.50 g of diethylenetriamine. The binder was then used for adhesion testing.

[0095] Example Performance Test Results

[0096] Performance testing: Heat resistance test method: The mixed adhesive was subjected to thermogravimetric analysis. The experimental conditions were a heating rate of 2℃ / min and a temperature range of 20~800℃. The results are shown in Table 1.

[0097] Peel strength test: The peel strength of the composite materials prepared in the examples and comparative examples was tested in accordance with GB / T 2791-1995 Adhesives T Peel Strength Test Method Flexible Materials to Flexible Materials. The results are shown in Table 1.

[0098] Tensile strength test of adhesive layer: The adhesive was prepared according to the examples and comparative examples. The adhesive was added to the mold to prepare mechanical specimens. The tensile strength of the composite materials prepared in the examples and comparative examples was tested with reference to GB / T 30776-2014 Test method for tensile strength and elongation at break of adhesive tape. The results are shown in Table 1.

[0099] Table 1. Results of adhesive bonding performance tests

[0100]

[0101] As shown in Table 1:

[0102] 1) Based on the comparison of Comparative Example 1 and Comparative Example 2, the properties of pure TTOYA resin are all higher than those of E-51 resin.

[0103] 2) By comparing the comparative examples and the embodiments, it was found that the performance of the sample after mixing TTOYA resin and E-51 resin was higher than that of the two pure samples. This phenomenon indicates that the compound use of TTOYA resin and E-51 resin has a synergistic effect.

[0104] 3) Factors affecting the bonding performance of synthetic resins include crosslinking density and the wettability of the resin to the bonded material. Because synthetic resins are in powder form and composed of rigid groups, pure TTOYA cannot be fully crosslinked during curing and has poor wettability with the bonded material, resulting in poor performance.

[0105] 4) In the examples, when TTOYA and E-51 resin are used together, the addition of E-51 resin can significantly improve the wettability of the mixed resin and the bonded material. Since E-51 resin can uniformly disperse and fuse TTOYA resin, the crosslinking density is significantly increased after curing, and thus all properties are improved.

Claims

1. A method for preparing a high heat-resistant epoxy adhesive, characterized in that, The high heat-resistant epoxy adhesive comprises epoxy adhesive resin 4,4',4''-(1,3,5-triazine-2,4,6-triyl)tris(N,N-bis(ethylene oxide-2-ylmethyl)aniline), and the preparation method of the epoxy adhesive resin 4,4',4''-(1,3,5-triazine-2,4,6-triyl)tris(N,N-bis(ethylene oxide-2-ylmethyl)aniline) includes the following steps: 1) p-Bromoaniline and p-methoxybenzyl chloride were dissolved separately in N,N-dimethylformamide. The p-Bromoaniline-N,N-dimethylformamide solution was added to a three-necked flask, and the methoxybenzyl chloride-N,N-dimethylformamide mixed solution was added to a constant pressure dropping funnel and then added dropwise to the three-necked flask. Triethylamine was added to the three-necked flask, the temperature was raised, and the mixture was stirred. The reaction was carried out at a certain temperature for a certain time. After cooling, the crystals were removed, washed with water, and dried to obtain 4-bromo-N,N-bis(4-methoxybenzyl)aniline, denoted as BMBA. 2) The BMBA prepared in step 1) is dried and dehydrated, added to tetrahydrofuran containing molecular sieves, and magnesium shavings and elemental iodine are added sequentially under stirring to obtain a reaction solution. The reaction solution is deoxygenated under nitrogen protection and heated until no more bubbles emerge from the solution to obtain (4-(bis(4-methoxybenzyl)amino)phenyl)magnesium bromide, i.e. Grignard reagent; 3) Dissolve cyanuric chloride in tetrafluorohydroran, heat the solution, add the Grignard reagent synthesized in step 2) dropwise, and stir the reaction for a period of time to obtain 4,4',4''-(1,3,5-triazine-2,4,6-triyl)tris(N,N-bis(4-methoxybenzyl)aniline), denoted as TTMA; 4) Dissolve the TTMA obtained in step 3) in dichloromethane, add trifluoroacetic acid dropwise to react, and after reacting for a period of time, wash the solution with saturated sodium bicarbonate aqueous solution, titrate the pH to neutral, and separate and extract 4,4',4''-(1,3,5-triazine-2,4,6-triyl)triphenylamine, denoted as TTA; 5) Add the TTA prepared in step 4) to epichlorohydrin, react in a three-necked flask, add tetrabutylammonium bromide, stir the reaction at a certain temperature, and obtain a mixture of chlorohydrin ethers. 6) Add the sodium hydroxide aqueous solution to the chlorohydrin ether mixture in step 5), cool and react for a period of time, stir, filter, extract, remove solvent by rotary evaporation, wash, and dry to obtain epoxy adhesive resin 4,4',4''-(1,3,5-triazine-2,4,6-triyl)tris(N,N-bis(ethylene oxide-2-ylmethyl)aniline), denoted as TTOYA.

2. The method for preparing a high heat-resistant epoxy adhesive as described in claim 1, characterized in that, In step 1), the molar ratio of p-bromoaniline to N,N-dimethylformamide is 1:90-130, and the volume ratio of p-methoxybenzyl chloride to N,N-dimethylformamide is 1:5-15. The molar ratio of p-bromoaniline, p-methoxybenzyl chloride, and triethylamine is 1:2-2.2:2-2.2; the rotor stirring speed is 200-500 rpm; the reaction temperature is 75-85℃; and the reaction time is 3-4 h. The volume ratio of water to N,N-dimethylformamide is 1:0.9-1.1; the product is washed with water 2-3 times; and the obtained product is dried at 75-85℃ for 1-2 h.

3. The method for preparing a high heat-resistant epoxy adhesive as described in claim 1, characterized in that, In step 2), the molar ratio of BMBA to Mg is 1:1-1.4, the molar ratio of BMBA to tetrahydrofuran is 1:10-15, the molar ratio of added iodine to BMBA is 1:20-30, the stirring rate is 300-400 rpm, the reaction temperature is 30-40℃, and the reaction time is 4-5 h.

4. The method for preparing a high heat-resistant epoxy adhesive as described in claim 1, characterized in that, In step 3), the molar ratio of cyanuric chloride to tetrahydrofuran is 1:50-70, the temperature is raised to 75-85℃, and the rotor stirring speed is 300-500rpm; the molar ratio of cyanuric chloride to Grignard reagent is 1:3-3.2, the dropping rate is 10-15 drops / min, and the reaction time is 7-9h.

5. The method for preparing a high heat-resistant epoxy adhesive as described in claim 1, characterized in that, In step 4), the molar ratio of TTMA to dichloromethane is 1:500-700, the molar ratio of TTMA to trifluoroacetic acid is 1:6-9, the reaction temperature is 0-50℃, the rotor speed is 300-500 rpm, the reaction time is 6-10h, and the solution pH range is 6.9-7.

1.

6. The method for preparing a high heat-resistant epoxy adhesive as described in claim 1, characterized in that, In step 5), the molar ratio of TTA to epichlorohydrin is 1:36-80, the mass ratio of TTA to tetrabutylammonium bromide is 1:1-1.6, the reaction system temperature is 70-100℃, the stirring speed is 200-350 rpm, and the reaction time is 2.5-4h.

7. The method for preparing a high heat-resistant epoxy adhesive as described in claim 1, characterized in that, In step 6), the mass concentration of the sodium hydroxide aqueous solution is 30%-70%, the volume ratio of the sodium hydroxide aqueous solution to the chlorohydrin ether mixture is 1:20-30, the reaction temperature is 50-70℃, the reaction time is 2.5-4h, and the stirring speed is 200-350 rpm.

8. The method for preparing a high heat-resistant epoxy adhesive as described in claim 1, characterized in that, In step 6), the detergent is a mixture of deionized water and epichlorohydrin, with a volume ratio of deionized water to epichlorohydrin of 1:0.8-2. The extraction solvent is toluene, and the volume of toluene added is 0.2-0.4 times the volume of the filtrate. Then, it is washed 3-5 times with 2-4 times the volume of toluene in deionized water.

9. The method for preparing a high heat-resistant epoxy adhesive as described in claim 1, characterized in that, In step 6), during the solvent removal step, the extracted organic phase is dried using a rotary evaporator with a vacuum range of 0.08 to -0.1 MPa, a rotary evaporation temperature of 40-60℃, and a rotary drying time of 20-50 min.

10. The use of the adhesive prepared by any one of claims 1-9 in brake pad adhesives.

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