Preparation method of high-temperature-resistant and high-humidity-resistant adhesive

Abstract

The invention relates to the technical field of adhesives, and discloses a preparation method of a high-temperature-resistant and high-humidity-resistant adhesive, the high-temperature-resistant and high-humidity-resistant adhesive comprises a component A and a component B. The component A comprises 100 parts by weight of epoxy resin and 0.3-0.8 part by weight of a defoaming agent; 68-80 parts by weight of a component B adamantane curing agent; the adamantane curing agent provided by the invention contains an adamantane structure with unique heat resistance and structural stability and a flexible and hydrophobic alkyl long chain, after an epoxy resin adhesive is cured, the water absorption rate of a cured product is very low, the water resistance and moisture resistance of the epoxy resin adhesive are favorably improved, and when the relative humidity is 80%, the water absorption rate of the cured product is greatly improved. And the adhesive still keeps very high shear strength and bonding performance. And the flexible alkyl long chain can play a very good toughening role, and is beneficial to improving the bending strength and the impact toughness. Meanwhile, the high temperature resistance of the adhesive is improved.

Description

Technical Field

[0001] The invention relates to the technical field of adhesives, and in particular to a method for preparing an adhesive resistant to high temperature and high humidity. Background Art

[0002] Epoxy resin adhesives have the advantages of good bonding performance, high mechanical strength, and low cost. They are widely used in label paper bonding, sporting goods, furniture and building materials, electronic appliances, etc. Modifying epoxy resins to improve their toughness, high temperature resistance, moisture resistance and other properties is of great significance. Developing new high-performance curing agents is an effective way to improve the toughness and high temperature resistance of epoxy resins.

[0003] Adamantane is a unique cage-like compound with strong structural stability and high heat resistance. It has broad practical applications in materials such as epoxy resins. Patent CN114685743B discloses a low-temperature curing agent for epoxy resin and a preparation method thereof. Adamantane diamine, diisocyanate and terminal amino polyether are reacted to obtain an adamantane-modified diamine, which is then reacted with cardanol or ginkgo biphenol, formaldehyde or polyformaldehyde to obtain a low-temperature curing agent for epoxy resin, which can achieve curing suitable for epoxy resin at low to medium temperatures and play a toughening role. The adamantane curing agent prepared by the present invention can not only play a toughening role, but also improve the high temperature resistance and moisture resistance of epoxy resin adhesives. Summary of the invention

[0004] (I) Technical problems to be solved: In view of the deficiencies in the prior art, the present invention provides a method for preparing an epoxy resin adhesive having high temperature and high humidity resistance.

[0005] (II) Technical solution: A high temperature and high humidity resistant adhesive is composed of component A and component B, wherein component A includes 100 parts by weight of epoxy resin and 0.3-0.8 parts by weight of defoaming agent; component B includes 68-80 parts by weight of adamantane curing agent.

[0006] The general chemical structure of adamantane curing agent is as follows: , n is any integer between 8 and 12.

[0007] The preparation method of the high temperature and high humidity resistant adhesive is as follows: adding epoxy resin and defoaming agent into a container, stirring and mixing to obtain component A, and then adding component B adamantane curing agent to obtain the high temperature and high humidity resistant adhesive.

[0008] Wherein, the preparation method of adamantane curing agent is: Step (1), add N,N-dimethylformamide, 1,3-dibromoadamantane, 3-carboxy-5-nitrobenzeneboric acid, and tetrakis(triphenylphosphine)palladium into a flask, stir, then add an aqueous solution of potassium carbonate, stir and react at 100-120° C. for 18-24 hours, add water to dilute, then extract with ethyl acetate, dry the organic phase over anhydrous sodium sulfate, concentrate the filtrate under reduced pressure, and recrystallize with ethanol to obtain intermediate A.

[0009] Step (2), add toluene, intermediate A, alkyl alcohol and p-toluenesulfonic acid into a flask, stir and react at 85-100° C. for 10-16 hours, distill under reduced pressure, wash with petroleum ether, and recrystallize the product with ethyl acetate to obtain intermediate B.

[0010] Step (3), add ethanol, intermediate B, palladium carbon catalyst to a flask, dropwise add hydrazine hydrate solution, stir and condense under reflux at 75-80°C for 24-36h, filter and recover the catalyst, distill the filtrate under reduced pressure, and then separate by silica gel column chromatography, and gradiently elute with a solution of ethyl acetate and petroleum ether to obtain adamantane curing agent. The reaction route is: .

[0011] Wherein, in step (1), the molar ratio of 1,3-dibromoadamantane, 3-carboxy-5-nitrophenylboric acid, tetrakis(triphenylphosphine)palladium and potassium carbonate is 1:(2-2.2):(0.06-0.08):(2.6-3.2).

[0012] Wherein, in step (2), the molar ratio of intermediate A, alkyl alcohol, and p-toluenesulfonic acid is 1:(2-2.8):(0.07-0.11). The general chemical structure formula of alkyl alcohol is , n is any integer between 8 and 12.

[0013] Wherein, in step (3), the mass ratio of intermediate B, palladium-carbon catalyst, and hydrazine hydrate solution is 1:(0.032-0.036):(6-9); and the mass fraction of hydrazine hydrate solution is 80%.

[0014] (III) Technical effect: The present invention uses 1,3-dibromoadamantane, 3-carboxy-5-nitrobenzeneboric acid, alkyl alcohol and the like as reactants, and obtains a novel adamantane curing agent for epoxy resin adhesive through Suzuki coupling reaction, esterification reaction and nitro reduction reaction.

[0015] The adamantane curing agent of the present invention contains a unique adamantane structure with heat resistance and structural stability, as well as a flexible and hydrophobic alkyl long chain. After curing the epoxy resin adhesive, the water absorption rate of the cured product is very low, which is beneficial to improving the water resistance and moisture resistance of the epoxy resin adhesive. At a high relative humidity of 80%, the adhesive still maintains very high shear strength and bonding performance. In addition, the flexible alkyl long chain can play a good toughening role, which is beneficial to improving the bending strength and impact toughness.

[0016] The present invention introduces a heat-resistant adamantane structure into the epoxy resin adhesive curing system, thereby increasing the initial thermal decomposition temperature and the maximum thermal decomposition rate temperature of the adhesive blend, and exhibiting good high temperature resistance. DETAILED DESCRIPTION

[0017] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0018] Example 1 Step (1), add 300mL N,N-dimethylformamide, 40mmol 1,3-dibromoadamantane, 80mmol 3-carboxy-5-nitrobenzeneboric acid, 3.2mmol tetrakis(triphenylphosphine)palladium into a flask, stir and add 30mL aqueous solution containing 96mmol potassium carbonate, stir and react at 110°C for 24h, add water to dilute, then extract with ethyl acetate, dry the organic phase over anhydrous sodium sulfate, concentrate the filtrate under reduced pressure, and recrystallize from ethanol to obtain intermediate A. The structural formula is: .

[0019] Step (2), add 400 mL of toluene, 50 mmol of intermediate A, 100 mmol of 1-octanol, and 4.2 mmol of p-toluenesulfonic acid into a flask, stir and react at 85°C for 16 h, distill under reduced pressure, wash with petroleum ether, and recrystallize the product with ethyl acetate to obtain intermediate B. The structural formula is as follows: .

[0020] Step (3), add 250mL ethanol, 6g intermediate B, 0.216g palladium carbon catalyst to the flask, dropwise add 48g hydrazine hydrate solution with a mass fraction of 80%, stir and reflux at 75°C for 36h, filter and recover the catalyst, distill the filtrate under reduced pressure, and then separate by silica gel column chromatography, and gradient elute with a solution of ethyl acetate and petroleum ether to obtain adamantane curing agent. The structural formula is as follows: .

[0021] Step (4), add 100g of epoxy resin E44 and 0.4g of defoamer into a container, stir and mix to obtain component A, and then add 68g of component B adamantane curing agent to obtain an adhesive resistant to high temperature and humidity.

[0022] Example 2 Step (1), add 260 mL of N,N-dimethylformamide, 40 mmol of 1,3-dibromoadamantane, 80 mmol of 3-carboxy-5-nitrobenzeneboric acid, and 2.8 mmol of tetrakis(triphenylphosphine)palladium into a flask, stir, add 30 mL of an aqueous solution containing 96 mmol of potassium carbonate, stir and react at 120° C. for 18 h, add water to dilute, then extract with ethyl acetate, dry the organic phase over anhydrous sodium sulfate, concentrate the filtrate under reduced pressure, and recrystallize from ethanol to obtain intermediate A.

[0023] Step (2), add 500 mL of toluene, 50 mmol of intermediate A, 120 mmol of 1-decanol, and 5.5 mmol of p-toluenesulfonic acid into a flask, stir and react at 85°C for 16 h, distill under reduced pressure, wash with petroleum ether, and recrystallize the product with ethyl acetate to obtain intermediate B.

[0024] Step (3), add 200 mL of ethanol, 6 g of intermediate B, 0.192 g of palladium carbon catalyst into a flask, dropwise add 54 g of 80% by mass hydrazine hydrate solution, stir and reflux at 80° C. for 24 h, filter and recover the catalyst, distill the filtrate under reduced pressure, and then separate by silica gel column chromatography, and gradient elute with a solution of ethyl acetate and petroleum ether to obtain an adamantane curing agent.

[0025] Step (4), add 100g of epoxy resin E44 and 0.3g of defoamer into a container, stir and mix to obtain component A, and then add 72g of component B adamantane curing agent to obtain an adhesive resistant to high temperature and humidity.

[0026] Example 3 Step (1), add 300 mL of N,N-dimethylformamide, 40 mmol of 1,3-dibromoadamantane, 88 mmol of 3-carboxy-5-nitrobenzeneboric acid, and 3.2 mmol of tetrakis(triphenylphosphine)palladium into a flask, stir, add 30 mL of an aqueous solution containing 102 mmol of potassium carbonate, stir and react at 100° C. for 24 h, add water to dilute, then extract with ethyl acetate, dry the organic phase over anhydrous sodium sulfate, concentrate the filtrate under reduced pressure, and recrystallize from ethanol to obtain intermediate A.

[0027] Step (2), add 500 mL of toluene, 50 mmol of intermediate A, 140 mmol of undecanol, and 3.5 mmol of p-toluenesulfonic acid into a flask, stir and react at 100° C. for 10 h, distill under reduced pressure, wash with petroleum ether, and recrystallize the product with ethyl acetate to obtain intermediate B.

[0028] Step (3), add 2250 mL of ethanol, 6 g of intermediate B, 0.216 g of palladium carbon catalyst into a flask, dropwise add 36 g of 80% by mass hydrazine hydrate solution, stir and reflux at 75° C. for 36 h, filter and recover the catalyst, distill the filtrate under reduced pressure, and then separate by silica gel column chromatography, and gradient elute with a solution of ethyl acetate and petroleum ether to obtain an adamantane curing agent.

[0029] Step (4), add 100g of epoxy resin E44 and 0.3g of defoamer into a container, stir and mix to obtain component A, and then add 76g of component B adamantane curing agent to obtain an adhesive resistant to high temperature and humidity.

[0030] Example 4 Step (1), add 260 mL of N,N-dimethylformamide, 40 mmol of 1,3-dibromoadamantane, 84 mmol of 3-carboxy-5-nitrobenzeneboric acid, and 2.4 mmol of tetrakis(triphenylphosphine)palladium into a flask, stir, add 40 mL of an aqueous solution containing 128 mmol of potassium carbonate, stir and react at 110° C. for 24 h, add water to dilute, then extract with ethyl acetate, dry the organic phase over anhydrous sodium sulfate, concentrate the filtrate under reduced pressure, and recrystallize from ethanol to obtain intermediate A.

[0031] Step (2), add 450 mL of toluene, 50 mmol of intermediate A, 120 mmol of dodecanol, and 4.2 mmol of p-toluenesulfonic acid into a flask, stir and react at 90° C. for 16 h, distill under reduced pressure, wash with petroleum ether, and recrystallize the product with ethyl acetate to obtain intermediate B.

[0032] Step (3), add 250 mL of ethanol, 6 g of intermediate B, 0.204 g of palladium carbon catalyst into a flask, dropwise add 54 g of 80% by mass hydrazine hydrate solution, stir and reflux at 75° C. for 24 h, filter and recover the catalyst, distill the filtrate under reduced pressure, and then separate by silica gel column chromatography, and gradient elute with a solution of ethyl acetate and petroleum ether to obtain an adamantane curing agent.

[0033] Step (4), add 100g of epoxy resin E44 and 0.8g of defoamer into a container, stir and mix to obtain component A, and then add 80g of component B adamantane curing agent to obtain an adhesive resistant to high temperature and humidity.

[0034] Comparative Example 1 Step (1), add 300mL N,N-dimethylformamide, 40mmol 1,3-dibromoadamantane, 80mmol 4-aminophenylboronic acid, 3.2mmol tetrakis(triphenylphosphine)palladium to a flask, stir and add 30mL of an aqueous solution containing 96mmol potassium carbonate, stir and react at 110°C for 24h, add water to dilute, then extract with ethyl acetate, dry the organic phase with anhydrous sodium sulfate, concentrate the filtrate under reduced pressure, and recrystallize with ethanol to obtain an adamantane curing agent. The structural formula is as follows: .

[0035] Step (2), add 100g of epoxy resin E44 and 0.4g of defoamer into a container, stir and mix to obtain component A, and then add 68g of component B adamantane curing agent to obtain an adhesive resistant to high temperature and humidity.

[0036] Comparative Example 2 Step (1), add 300mL N,N-dimethylformamide, 40mmol 1,4-dibromobenzene, 80mmol 3-carboxy-5-nitrobenzeneboric acid, 3.2mmol tetrakis(triphenylphosphine)palladium to a flask, stir and add 30mL aqueous solution containing 96mmol potassium carbonate, stir and react at 110°C for 24h, add water to dilute, then extract with ethyl acetate, dry the organic phase over anhydrous sodium sulfate, concentrate the filtrate under reduced pressure, and recrystallize with ethanol to obtain intermediate 1. The structural formula is as follows: .

[0037] Step (2), add 400 mL of toluene, 50 mmol of intermediate 1, 100 mmol of 1-octanol, and 4.2 mmol of p-toluenesulfonic acid into a flask, stir and react at 85°C for 16 h, distill under reduced pressure, wash with petroleum ether, and recrystallize the product with ethyl acetate to obtain intermediate 2. The structural formula is as follows: .

[0038] Step (3), add 250mL ethanol, 6g intermediate 2, 0.216g palladium carbon catalyst to the flask, dropwise add 48g hydrazine hydrate solution with a mass fraction of 80%, stir and reflux at 75°C for 36h, filter and recover the catalyst, distill the filtrate under reduced pressure, and then separate by silica gel column chromatography, and gradient elute with a solution of ethyl acetate and petroleum ether to obtain a curing agent. The structural formula is as follows: .

[0039] Step (4), add 100g of epoxy resin E44 and 0.4g of defoamer into the container, stir and mix to obtain component A, and then add 68g of component B curing agent to obtain an adhesive resistant to high temperature and humidity.

[0040] Apply high temperature and high humidity resistant adhesive on the surface of two pieces of steel, bond them, place them in a constant temperature and humidity test box, control the relative humidity to 40-80%, cure them at 60℃ for 12h, then place them at 25℃ for 120h, and test the shear strength according to GB / T 7124-2008.

[0041] Pour the high temperature and high humidity resistant adhesive into the mold and cure it at 60℃ for 18h. Make the casting sample into a 5cm×5cm×5cm sample and soak it in distilled water for 360h. Take out the sample, wipe off the surface moisture, weigh it, and calculate the water absorption rate Q.

[0042] Q = (mass after water absorption - mass before water absorption) / mass before water absorption × 100%.

[0043] The flexural strength and impact toughness of the casting are tested in accordance with GB / T 2567-2021 standard.

[0044] 8 mg of the casting sample was weighed and placed in a thermogravimetric analyzer to perform a thermal property test in a nitrogen atmosphere with a heating rate of 10°C / min and a maximum temperature of 800°C.

[0045] Table 1

[0046] Table 2

[0047] As shown in Table 1 and Table 2, the adamantane curing agent of Example 1-4 contains a unique adamantane structure with heat resistance and structural stability, as well as a flexible and hydrophobic alkyl long chain. After the epoxy resin is cured, the water absorption rate of the cured product is very low, which is conducive to improving the water resistance and moisture resistance of the epoxy resin adhesive. At a high relative humidity of 80%, the adhesive still maintains very high shear strength and bonding performance. At the same time, the flexible alkyl long chain of the curing agent can play a good toughening effect, which is conducive to improving bending strength and impact toughness. And the heat-resistant adamantane structure is introduced into the epoxy resin adhesive curing system, and its initial thermal decomposition temperature and maximum thermal decomposition rate temperature are high, showing good high temperature resistance.

[0048] The adamantane curing agent of Comparative Example 1 does not contain hydrophobic and flexible alkyl long chains, and has a poor toughening effect. The bending strength and impact toughness of the epoxy resin adhesive are low, and the water absorption rate is large, and the water resistance and moisture resistance are poor. At a high relative humidity of 80%, the shear strength of the adhesive decreases significantly and the bonding performance deteriorates.

[0049] The curing agent of Comparative Example 2 does not contain adamantane structure, the initial thermal decomposition temperature and the maximum thermal decomposition rate temperature of the adhesive are low, and the high temperature resistance is poor.

[0050] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for preparing a high temperature and high humidity resistant adhesive, characterized in that: The high temperature and high humidity resistant adhesive is composed of component A and component B, wherein component A includes 100 parts by weight of epoxy resin and 0.3-0.8 parts by weight of defoamer; component B includes 68-80 parts by weight of adamantane curing agent; The chemical structure formula of the adamantane curing agent is as follows: , n is any integer between 8 and 12; The preparation method of the high temperature and high humidity resistant adhesive is as follows: epoxy resin and defoamer are added into a container, stirred and mixed to obtain component A, and then component B, adamantane curing agent, is added to obtain the high temperature and high humidity resistant adhesive.

2. The method for preparing a high temperature and high humidity resistant adhesive according to claim 1, characterized in that: The preparation method of the adamantane curing agent is: Step (1), adding N,N-dimethylformamide, 1,3-dibromoadamantane, 3-carboxy-5-nitrophenylboric acid, and tetrakis(triphenylphosphine)palladium into a flask, stirring, and then adding an aqueous solution of potassium carbonate, stirring for reaction, and then extracting and recrystallizing to obtain intermediate A; Step (2), add toluene, intermediate A, alkyl alcohol, and p-toluenesulfonic acid into a flask, stir for reaction, and then perform vacuum distillation, washing, and recrystallization to obtain intermediate B; Step (3), add ethanol, intermediate B, and palladium-carbon catalyst into a flask, dropwise add hydrazine hydrate solution, stir to react, filter, perform vacuum distillation, and perform silica gel column chromatography to obtain adamantane curing agent.

3. The method for preparing the high temperature and high humidity resistant adhesive according to claim 1, characterized in that: In the step (1), the molar ratio of 1,3-dibromoadamantane, 3-carboxy-5-nitrophenylboric acid, tetrakis(triphenylphosphine)palladium and potassium carbonate is 1:(2-2.2):(0.06-0.08):(2.6-3.2).

4. The method for preparing a high temperature and high humidity resistant adhesive according to claim 1, characterized in that: The reaction in step (1) is carried out at 100-120° C. for 18-24 hours.

5. The method for preparing the high temperature and high humidity resistant adhesive according to claim 1, characterized in that: In the step (2), the molar ratio of intermediate A, alkyl alcohol and p-toluenesulfonic acid is 1:(2-2.8):(0.07-0.11).

6. The method for preparing the high temperature and high humidity resistant adhesive according to claim 5, characterized in that: The chemical structure of the alkyl alcohol is , n is any integer between 8 and 12.

7. The method for preparing a high temperature and high humidity resistant adhesive according to claim 1, characterized in that: The reaction in step (2) is carried out at 85-100° C. for 10-16 hours.

8. The method for preparing a high temperature and high humidity resistant adhesive according to claim 1, characterized in that: In the step (3), the mass ratio of intermediate B, palladium-carbon catalyst, and hydrazine hydrate solution is 1:(0.032-0.036):(6-9); the mass fraction of hydrazine hydrate solution is 80%.

9. The method for preparing a high temperature and high humidity resistant adhesive according to claim 1, characterized in that: In the step (3), the reaction is condensed and refluxed at 75-80° C. for 24-36 hours.

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