Preparation method of high temperature and high humidity resistant adhesive

Abstract

The present invention relates to the technical field of adhesives, and discloses a preparation method of a high-temperature and high-humidity resistant adhesive, wherein 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 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 the epoxy resin adhesive 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. In addition, the flexible alkyl long chain can play a good toughening role, which is conducive to improving bending strength and impact toughness. At the same time, the high-temperature resistance of the adhesive is improved.

Description

Technical Field

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

[0002] Epoxy resin adhesives offer excellent bonding properties, high mechanical strength, and low cost, making them widely used in label paper bonding, sporting goods, furniture and building materials, and electronic appliances. Modifying epoxy resins to improve their toughness, heat resistance, and moisture resistance is crucial. Developing new, high-performance curing agents is an effective way to enhance epoxy resin's toughness and heat resistance.

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

[0004] (1) Technical Problems to be Solved: In response to the deficiencies of the prior art, the present invention provides a method for preparing an epoxy resin adhesive that is resistant to high temperature and high humidity.

[0005] (2) 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:

[0007] , n is any integer between 8 and 12.

[0008] The preparation method of the high-temperature and high-humidity resistant adhesive comprises the following steps: 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.

[0009] Wherein, the preparation method of adamantane curing agent is:

[0010] Step (1): Add N,N-dimethylformamide, 1,3-dibromoadamantane, 3-carboxy-5-nitrophenylboric acid, and tetrakis(triphenylphosphine)palladium to a flask, stir, then add an aqueous solution of potassium carbonate, stir and react at 100-120°C for 18-24h, 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.

[0011] 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.

[0012] Step (3): Add ethanol, intermediate B, and palladium-carbon catalyst to a flask, dropwise add hydrazine hydrate solution, stir and reflux at 75-80°C for 24-36 hours, filter and recover the catalyst, distill the filtrate under reduced pressure, and then separate by silica gel column chromatography, eluting with a gradient solution of ethyl acetate and petroleum ether to obtain an adamantane curing agent. The reaction route is:

[0013] .

[0014] 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).

[0015] 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 of alkyl alcohol is , n is any integer between 8 and 12.

[0016] 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); the mass fraction of hydrazine hydrate solution is 80%.

[0017] (III) Technical Effect: The present invention uses 1,3-dibromoadamantane, 3-carboxy-5-nitrophenylboric acid, alkyl alcohol, etc. as reactants, and obtains a novel adamantane curing agent for epoxy resin adhesive through Suzuki coupling reaction, esterification reaction and nitro reduction reaction.

[0018] The adamantane curing agent of the present invention contains a unique adamantane structure characterized by heat resistance and structural stability, as well as a flexible and hydrophobic long alkyl chain. After curing, the epoxy resin adhesive has a very low water absorption rate, which helps improve the epoxy resin adhesive's water resistance and moisture resistance. Even at a high relative humidity of 80%, the adhesive still maintains high shear strength and bonding properties. Furthermore, the flexible long alkyl chain provides excellent toughening, helping to improve flexural strength and impact toughness.

[0019] 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 excellent high-temperature resistance. DETAILED DESCRIPTION

[0020] 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 embodiments described 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 making creative efforts are within the scope of protection of the present invention.

[0021] Example 1

[0022] Step (1): Add 300 mL of N,N-dimethylformamide, 40 mmol of 1,3-dibromoadamantane, 80 mmol of 3-carboxy-5-nitrophenylboric acid, and 3.2 mmol of tetrakis(triphenylphosphine)palladium to a flask, stir, then add 30 mL of an aqueous solution containing 96 mmol of potassium carbonate, stir and react at 110°C for 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 from ethanol to obtain intermediate A. The structural formula is: .

[0023] 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 to 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:

[0024] .

[0025] Step (3): Add 250 mL of ethanol, 6 g of intermediate B, and 0.216 g of palladium-carbon catalyst to a flask, dropwise add 48 g of 80% by mass hydrazine hydrate solution, stir and reflux at 75°C for 36 hours, filter and recover the catalyst, and distill the filtrate under reduced pressure. Then, separate the filtrate by silica gel column chromatography and elute with a gradient of ethyl acetate and petroleum ether to obtain an adamantane curing agent. The structural formula is as follows:

[0026] .

[0027] Step (4): add 100 g of epoxy resin E44 and 0.4 g of defoamer into a container, stir and mix to obtain component A, and then add 68 g of component B adamantane curing agent to obtain a high temperature and high humidity resistant adhesive.

[0028] Example 2

[0029] Step (1): Add 260 mL of N,N-dimethylformamide, 40 mmol of 1,3-dibromoadamantane, 80 mmol of 3-carboxy-5-nitrophenylboric acid, and 2.8 mmol of tetrakis(triphenylphosphine)palladium to a flask, stir, then 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.

[0030] 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 to a flask, stir and react at 85°C for 16 h, distill under reduced pressure, wash with petroleum ether, and recrystallize the product from ethyl acetate to obtain intermediate B.

[0031] Step (3), add 200 mL of ethanol, 6 g of intermediate B, 0.192 g of palladium carbon catalyst to a flask, add dropwise 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 elute with a gradient solution of ethyl acetate and petroleum ether to obtain an adamantane curing agent.

[0032] Step (4): add 100 g of epoxy resin E44 and 0.3 g of defoamer into a container, stir and mix to obtain component A, and then add 72 g of component B adamantane curing agent to obtain a high temperature and high humidity resistant adhesive.

[0033] Example 3

[0034] Step (1): Add 300 mL of N,N-dimethylformamide, 40 mmol of 1,3-dibromoadamantane, 88 mmol of 3-carboxy-5-nitrophenylboric acid, and 3.2 mmol of tetrakis(triphenylphosphine)palladium to a flask, stir, then 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.

[0035] Step (2): Add 500 mL of toluene, 50 mmol of intermediate A, 140 mmol of undecyl alcohol, 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 from ethyl acetate to obtain intermediate B.

[0036] Step (3), add 2250mL of ethanol, 6g of intermediate B, 0.216g of palladium carbon catalyst to a flask, add dropwise 36g of 80% by mass hydrazine hydrate solution, 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 elute with a gradient solution of ethyl acetate and petroleum ether to obtain an adamantane curing agent.

[0037] Step (4): add 100 g of epoxy resin E44 and 0.3 g of defoamer into a container, stir and mix to obtain component A, and then add 76 g of component B adamantane curing agent to obtain a high temperature and high humidity resistant adhesive.

[0038] Example 4

[0039] Step (1): add 260 mL of N,N-dimethylformamide, 40 mmol of 1,3-dibromoadamantane, 84 mmol of 3-carboxy-5-nitrophenylboric acid, and 2.4 mmol of tetrakis(triphenylphosphine)palladium to 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, and then extract with ethyl acetate. The organic phase is dried over anhydrous sodium sulfate, the filtrate is concentrated under reduced pressure, and recrystallized from ethanol to obtain intermediate A.

[0040] Step (2): 450 mL of toluene, 50 mmol of intermediate A, 120 mmol of dodecanol, and 4.2 mmol of p-toluenesulfonic acid were added to a flask, and the mixture was stirred at 90°C for 16 h. The mixture was distilled under reduced pressure, washed with petroleum ether, and the product was recrystallized from ethyl acetate to obtain intermediate B.

[0041] Step (3), add 250 mL of ethanol, 6 g of intermediate B, 0.204 g of palladium carbon catalyst to a flask, add dropwise 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 elute with a gradient solution of ethyl acetate and petroleum ether to obtain an adamantane curing agent.

[0042] Step (4): add 100 g of epoxy resin E44 and 0.8 g of defoamer into a container, stir and mix to obtain component A, and then add 80 g of component B adamantane curing agent to obtain a high temperature and high humidity resistant adhesive.

[0043] Comparative Example 1

[0044] Step (1) Add 300 mL of N,N-dimethylformamide, 40 mmol of 1,3-dibromoadamantane, 80 mmol of 4-aminophenylboronic acid, and 3.2 mmol of tetrakis(triphenylphosphine)palladium to a flask, stir, then add 30 mL of an aqueous solution containing 96 mmol of potassium carbonate, stir and react at 110°C for 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 from ethanol to obtain an adamantane curing agent. The structural formula is as follows: .

[0045] Step (2): add 100 g of epoxy resin E44 and 0.4 g of defoamer into a container, stir and mix to obtain component A, and then add 68 g of component B adamantane curing agent to obtain a high temperature and high humidity resistant adhesive.

[0046] Comparative Example 2

[0047] Step (1): Add 300 mL of N,N-dimethylformamide, 40 mmol of 1,4-dibromobenzene, 80 mmol of 3-carboxy-5-nitrobenzeneboric acid, and 3.2 mmol of tetrakis(triphenylphosphine)palladium to a flask, stir, then add 30 mL of an aqueous solution containing 96 mmol of potassium carbonate, stir and react at 110°C for 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 from ethanol to obtain intermediate 1. The structural formula is as follows: .

[0048] 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 to a flask, stir and react at 85°C for 16 h, distill under reduced pressure, wash with petroleum ether, and recrystallize the product from ethyl acetate to obtain intermediate 2. The structural formula is as follows:

[0049] .

[0050] Step (3): Add 250 mL of ethanol, 6 g of intermediate 2, and 0.216 g of palladium-carbon catalyst to a flask, dropwise add 48 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, eluting with a gradient of ethyl acetate and petroleum ether to obtain a curing agent. The structural formula is as follows:

[0051] .

[0052] Step (4): add 100 g of epoxy resin E44 and 0.4 g of defoamer into the container, stir and mix to obtain component A, and then add 68 g of component B curing agent to obtain a high temperature and high humidity resistant adhesive.

[0053] Apply high-temperature and high-humidity resistant adhesive to the surface of two pieces of steel, bond them, place them in a constant temperature and humidity test chamber, control the relative humidity at 40-80%, cure them at 60°C for 12 hours, and then place them at 25°C for 120 hours. Test the shear strength according to GB / T 7124-2008.

[0054] 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.

[0055] Q = (mass after water absorption - mass before water absorption) / mass before water absorption × 100%.

[0056] The flexural strength and impact toughness of the casting are tested in accordance with GB / T 2567-2021 standard.

[0057] 8 mg of the casting sample was weighed and placed in a thermogravimetric analyzer. The thermal properties were tested in a nitrogen atmosphere at a heating rate of 10°C / min and a maximum temperature of 800°C.

[0058] Table 1

[0059]

[0060] Table 2

[0061]

[0062] As shown in Tables 1 and 2, the adamantane curing agents of Examples 1-4 contain a unique adamantane structure with unique 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 properties. At the same time, the flexible alkyl long chain of the curing agent can play a good toughening role, which is conducive to improving flexural strength and impact toughness. In addition, 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.

[0063] The adamantane curing agent of Comparative Example 1 does not contain hydrophobic and flexible long alkyl chains, and has a poor toughening effect. The epoxy resin adhesive has low bending strength and impact toughness, and has a large water absorption rate, poor water resistance and moisture resistance. At a high relative humidity of 80%, the shear strength of the adhesive decreases significantly and the bonding performance deteriorates.

[0064] The curing agent of Comparative Example 2 does not contain an adamantane structure, and the initial thermal decomposition temperature and the maximum thermal decomposition rate temperature of the adhesive are low, and the high temperature resistance is poor.

[0065] 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 principles of the present invention should be included in the scope of protection 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 comprises the following steps: adding epoxy resin and defoaming agent into a container, stirring and mixing to obtain component A, and then adding component B, which is an adamantane curing agent, to obtain the high-temperature and high-humidity resistant adhesive.

2. The method for preparing the 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, 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 distill under reduced pressure, wash, and recrystallize 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, distill under reduced pressure, and separate by silica gel column chromatography to obtain an adamantane curing agent.

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

8. The method for preparing the high temperature and high humidity resistant adhesive according to claim 2, 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 the high temperature and high humidity resistant adhesive according to claim 2, wherein: In step (3), the reaction is condensed and refluxed at 75-80° C. for 24-36 hours.

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