A kind of aging-resistant polyurethane adhesive with high bonding strength and preparation method thereof

Abstract

The invention discloses a high-bonding-strength aging-resistant polyurethane adhesive and a preparation method thereof, and belongs to the field of adhesive processing technology. It is used to solve the technical problem that the bonding strength and aging resistance of polyurethane adhesives in the prior art need to be further improved. A high-bonding-strength aging-resistant polyurethane adhesive comprises the following components by weight: 90-100 parts of composite polyurethane, 13-15 parts of anti-aging modified particles, 7-9 parts of activated graphene, 8-10 parts of 3-aminopropyltriethoxysilane, and 15-20 parts of dimethyl sulfoxide. The present invention enhances and modifies composite polyurethane by anti-aging modified particles, activated graphene, and 3-aminopropyltriethoxysilane, thereby effectively improving the bonding strength and tensile properties of the polyurethane adhesive and also improving its resistance to wet heat aging and UV aging performance.

Description

Technical Field

[0001] The invention relates to the technical field of adhesive processing, and in particular to an aging-resistant polyurethane adhesive with high bonding strength and a preparation method thereof. Background Art

[0002] With the continuous development of industrial technology, the performance requirements for adhesives are also increasing. Especially in some special environments such as high temperature, high humidity, and strong ultraviolet radiation, the bond strength and aging resistance of adhesives have become important indicators of their quality. Polyurethane adhesives are an important component of the rapidly developing polyurethane resin. They have excellent shear strength and impact resistance, suitable for various structural bonding fields, and have excellent flexibility.

[0003] The polyurethane adhesives in the prior art have the problem of insufficient aging resistance. When exposed to humidity, heat, light and other environments for a long time, they are prone to phenomena such as decreased bonding strength, yellowing, and cracking, which seriously affect their service life and application range. In order to improve the aging resistance of polyurethane adhesives, antioxidants and light stabilizers are usually added to the polyurethane adhesive materials, or polyol materials with special structures are introduced into the materials. However, due to the compatibility between the materials, these added materials are difficult to be evenly dispersed in the polyurethane adhesive. In addition, added materials such as antioxidants and light stabilizers are easy to migrate from the materials, resulting in the bonding strength and aging resistance of the polyurethane adhesive needing to be further improved, affecting the long-term stability and performance of the adhesive.

[0004] In view of the technical defects in this aspect, a solution is now proposed. Summary of the Invention

[0005] The object of the present invention is to provide an aging-resistant polyurethane adhesive with high bonding strength and a preparation method thereof, so as to solve the technical problem in the prior art that the bonding strength and aging resistance of polyurethane adhesives need to be further improved.

[0006] The purpose of the present invention can be achieved through the following technical solutions:

[0007] A high-bonding-strength, aging-resistant polyurethane adhesive comprises the following components in parts by weight: 90-100 parts of composite polyurethane, 13-15 parts of aging-resistant modified particles, 7-9 parts of activated graphene, 8-10 parts of 3-aminopropyltriethoxysilane, and 15-20 parts of dimethyl sulfoxide;

[0008] The preparation method of the composite polyurethane comprises the following steps: under the protection of an inert gas atmosphere, mixing polytetramethylene glycol, hydroxy silicone oil, diisocyanate and dimethyl sulfoxide, raising the temperature of the reaction system to 80-90° C., adding a catalyst to the reaction system, carrying out a heat preservation reaction for 90-120 minutes, adding a chain extender to the reaction system, carrying out a heat preservation reaction for 60-80 minutes, and performing post-processing to obtain the composite polyurethane.

[0009] The synthetic reaction formula of composite polyurethane is:

[0010]

[0011] Where:

[0012] R1:

[0013] R2:

[0014] The synthetic reaction mechanism of composite polyurethane is:

[0015] During the reaction, the hydroxyl groups on the polytetramethylene glycol and hydroxy silicone oil molecules undergo condensation reaction with the isocyanate groups on the diisocyanate molecules to generate a polyurethane prepolymer in which isocyanate-terminated polytetramethylene glycol and polysiloxane are co-embedded. Then, the isocyanate groups on the polyurethane prepolymer molecules undergo condensation reaction with the amino groups on the melamine molecules to increase the crosslinking degree of the polyurethane prepolymer and prepare a composite polyurethane.

[0016] Furthermore, the amount ratio of the polytetrahydrofuran diol, hydroxy silicone oil, dimethyl sulfoxide, catalyst and chain extender is 20g:3g:20mL:0.2g:4g, the chain extender is melamine, the catalyst is dibutyltin dilaurate, the diisocyanate is any one of isophorone diisocyanate and toluene diisocyanate, the amount of the diisocyanate is calculated by NCO / OH=1.5, wherein the hydroxyl group is the molar amount of the hydroxyl group in the molecules of the polytetrahydrofuran diol and the hydroxy silicone oil, and the post-processing comprises: after the reaction is completed, the temperature of the reaction system is reduced to room temperature, and the product is screened through a 100-mesh sieve to obtain a composite polyurethane.

[0017] Furthermore, the preparation method of the anti-aging modified particles is: mixing epoxy-modified titanium dioxide, 3,5-di-tert-butyl-4-hydroxybenzyl alcohol, N,N-dimethylformamide and a catalyst, raising the temperature of the reaction system to 80-90°C, keeping the reaction warm for 4-6 hours, and post-treating to obtain the anti-aging modified particles.

[0018] The synthetic reaction formula of anti-aging modified particles is:

[0019] In the formula

[0020] R3:

[0021] The synthetic reaction mechanism of anti-aging modified particles is:

[0022] During the reaction, the epoxy groups on the surface of the epoxy-modified titanium dioxide undergo a ring-opening condensation reaction with 3,5-di-tert-butyl-4-hydroxybenzyl alcohol to form butylated hydroxytoluene and hydroxyl modifications on the epoxy-modified titanium dioxide particles, thereby preparing anti-aging modified particles.

[0023] Furthermore, the epoxy-modified titanium dioxide, 3,5-di-tert-butyl-4-hydroxybenzyl alcohol, N,N-dimethylformamide and catalyst are used in a ratio of 10g:3g:50mL:1g, the catalyst is triethylamine, and the post-treatment includes: after the reaction is completed, the temperature of the reaction system is lowered to room temperature, filtered, the filter cake is washed three times with anhydrous ethanol and then dried, the filter cake is transferred to a drying oven at a temperature of 50-60°C, and vacuum dried to constant weight to obtain anti-aging modified particles.

[0024] Furthermore, the preparation method of epoxy-modified titanium dioxide is as follows: nano-titanium dioxide, KH-560, and anhydrous ethanol are mixed, the reaction system temperature is increased to 45-55° C., a catalyst is added to the reaction system, the reaction is kept warm for 60-80 minutes, and post-processed to obtain epoxy-modified titanium dioxide.

[0025] The synthetic reaction formula of epoxy modified titanium dioxide is:

[0026]

[0027] Where: It is nano titanium dioxide particles.

[0028] The synthetic reaction mechanism of epoxy modified titanium dioxide is:

[0029] During the reaction, the siloxane bonds on the KH-560 molecules are hydrolyzed to form silanols, which react with the active groups on the surface of the nano-titanium dioxide particles to form chemical bonds, forming epoxy modifications on the nano-titanium dioxide particles to prepare epoxy-modified titanium dioxide.

[0030] Furthermore, the amount ratio of the nano-titanium dioxide, KH-560, anhydrous ethanol and catalyst is 5g:2g:50mL:10mL, the catalyst is a 2-3wt% sodium hydroxide aqueous solution, and the post-treatment includes: after the reaction is completed, the temperature of the reaction system is lowered to room temperature, filtered, the filter cake is washed with purified water until neutral and then dried, the filter cake is transferred to a drying oven at a temperature of 50-60°C, and vacuum dried to constant weight to obtain epoxy-modified titanium dioxide.

[0031] Furthermore, activated graphene is obtained by processing the following steps:

[0032] A1. Under an inert gas atmosphere, graphene oxide, N,N-dimethylformamide, and a catalyst are mixed, the temperature of the reaction system is lowered to 3-5°C, chloroacetyl chloride is added dropwise to the reaction system, and after the addition is complete, the reaction is kept warm for 60-80 minutes, the temperature of the reaction system is raised to room temperature, the reaction is kept warm for 10-12 hours, and post-processed to obtain halogenated graphene;

[0033] A2. Under an inert gas atmosphere, halogenated graphene, 3-butene-1-ol, a catalyst, and N,N-dimethylformamide are mixed, the reaction system temperature is raised to 85-95°C, the reaction is kept warm for 8-10 hours, and post-processed to obtain activated graphene.

[0034] The synthetic reaction mechanism of activated graphene is:

[0035] The chlorine atoms of chloroacetyl chloride have high reactivity. During the reaction process, the catalyst catalyzes acetyl chloride to easily undergo a substitution reaction with the hydroxyl or carboxyl groups on the surface of graphene oxide, accelerates the reaction of chloroacetyl chloride with graphene oxide, and forms a halogen modification on the surface of graphene oxide. Then, under the action of the catalyst, 3-butene-1-ol undergoes a substitution addition reaction with the halogen on the halogenated graphene molecule, forming an alcoholic hydroxyl modification on the molecule, thereby preparing activated graphene.

[0036] Furthermore, in step A1, the amount ratio of the graphene oxide, N,N-dimethylformamide, catalyst and chloroacetyl chloride is 5g:100mL:0.1g:3g, and the catalyst is composed of 4-dimethylaminopyridine and triethylamine in a weight ratio of 1:3. The post-treatment includes: after the reaction is completed, filtering, washing the filter cake three times with dichloromethane and then drying, transferring the filter cake to a drying oven at a temperature of 50-60°C, and vacuum drying to constant weight to obtain halogenated graphene.

[0037] Furthermore, in step A2, the halogenated graphene, 3-butene-1-ol, catalyst and N,N-dimethylformamide are used in a ratio of 3g:5g:0.1g:30mL, the catalyst is cuprous chloride, and the post-treatment includes: after the reaction is completed, the temperature of the reaction system is lowered to room temperature, filtered, the filter cake is washed three times with dichloromethane and then dried, the filter cake is transferred to a drying oven at a temperature of 50-60°C, and vacuum dried to constant weight to obtain activated graphene.

[0038] The present application also proposes a method for preparing an aging-resistant polyurethane adhesive with high bonding strength. The method for preparing the aging-resistant polyurethane adhesive with high bonding strength is as follows: under the protection of an inert gas atmosphere, composite polyurethane, anti-aging modified particles, activated graphene, 3-aminopropyltriethoxysilane and dimethyl sulfoxide are uniformly mixed to obtain a polyurethane adhesive.

[0039] The present invention has the following beneficial effects:

[0040] 1. The aging-resistant polyurethane adhesive of the present application is prepared by mixing a composite polyurethane terminated with an isocyanate group with anti-aging modified particles, activated graphene and 3-aminopropyltriethoxysilane to obtain a polyurethane adhesive. During the mixing process, the isocyanate groups on the composite polyurethane molecules can condense with the active groups such as hydroxyl groups and amino groups on the anti-aging modified particles, activated graphene or 3-aminopropyltriethoxysilane molecules, thereby increasing the cross-linking degree between molecules and forming a tighter network structure between the polyurethane adhesive molecules, thereby strengthening the molecular The interaction force between them, in the composite polyurethane, polytetramethylene glycol provides flexibility and adhesion, and its ether bond forms hydrogen bond with the surface of the substrate to enhance the interfacial bonding strength. The siloxy bond in the hydroxy silicone oil has low surface energy, which can improve the wettability of the adhesive to the low surface energy substrate and enhance the interfacial bonding. In addition, the introduction of 3-aminopropyltriethoxysilane introduces triethoxysilane into the polyurethane adhesive, which hydrolyzes in the air environment to form highly active silanols and reacts with other active functional groups, thereby improving the bonding strength between the adhesive and the adherend.

[0041] 2. The aging-resistant polyurethane adhesive of the present application improves the flexibility of the composite polyurethane molecules by introducing polyurethane prepolymer segments co-embedded with polytetramethylene ether and polysiloxane into the composite polyurethane molecules. The rigid structure melamine acts as a chain extender to increase the crosslinking density of the composite polyurethane, making the network structure of the polyurethane adhesive tighter. The flexible polyurethane prepolymer compensates for the brittleness caused by the rigid melamine and crosslinking, so that the adhesive layer maintains high tensile properties. In the composite polyurethane molecules, polytetramethylene ether and polysiloxane have good hydrolysis stability and are not easy to break in a hot and humid environment. The triazine ring structure of melamine has high thermal stability, which cooperates with the crosslinking structure of the composite polyurethane to limit the movement of the polyurethane molecular chain at high temperature, thereby improving its thermal stability and enhancing the heat and humidity resistance of the polyurethane adhesive.

[0042] 3. The aging-resistant polyurethane adhesive of the present application uses titanium dioxide as a base material, performs epoxidation modification on it, and then performs butylated hydroxytoluene and hydroxyl modification, thereby increasing the compatibility of the aging-resistant modified particles with the polymer matrix. Titanium dioxide as an inorganic particle can scatter or absorb ultraviolet rays, while butylated hydroxytoluene as a hindered phenol can capture free radicals and delay aging, so that the aging-resistant modified particles can provide UV stability and oxidation resistance at the same time, thereby improving the moisture and heat resistance and UV resistance. By activating and modifying graphene and modifying alkyl alcohol on the graphene particles, the dispersibility of the activated graphene in the composite polyurethane is enhanced. The high specific surface area and excellent dispersibility of the activated graphene enable it to form more interface bonding points in the polyurethane adhesive. These interface bonding points can more effectively transmit stress and further improve the bonding strength. In addition, graphene has excellent thermal stability, and its sp2 The hybrid carbon network can absorb UV photons and convert light energy into heat energy through electron-hole pair recombination, reducing the damage of ultraviolet rays to polyurethane and further improving the heat resistance and UV resistance of polyurethane adhesives. DETAILED DESCRIPTION

[0043] The technical solutions of the present invention will be clearly and completely described below in conjunction with the embodiments. Obviously, the embodiments described are only some embodiments of the present invention, not all 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.

[0044] In this application, polytetrahydrofuran diol was selected from Jining Fangyu Chemical Co., Ltd., with a molecular weight of 650±25;

[0045] In this application, the hydroxy silicone oil is a dihydroxy-terminated polysiloxane selected from Wuhan Kemik Biopharmaceutical Technology Co., Ltd., with an active ingredient content of 99.30, model number l1258437, and product code 662-173-7;

[0046] In the present application, the particle size of graphene oxide is 4 μm-0.335 nm.

[0047] Example 1

[0048] This embodiment provides a method for preparing an aging-resistant polyurethane adhesive with high bonding strength, comprising the following steps:

[0049] S1. Preparation of composite polyurethane

[0050] Under an inert gas atmosphere, 40 g of polytetrahydrofuran diol, 6 g of hydroxy silicone oil, and 40 mL of dimethyl sulfoxide were weighed and added to a nitrogen-protected three-necked flask with stirring. According to the calculated amount of NCO / OH=1.5, the calculated amount of isophorone diisocyanate was added to the three-necked flask. The temperature of the reaction system was raised to 80° C., 0.4 g of dibutyltin dilaurate as a catalyst was added to the reaction system, and the reaction was kept warm for 90 min. 8 g of melamine as a chain extender was added to the reaction system, and the reaction was kept warm for 60 min. The temperature of the reaction system was lowered to room temperature, and the mixture was screened through a 100-mesh sieve to obtain a composite polyurethane.

[0051] S2. Preparation of anti-aging modified particles

[0052] Weigh: 50 g of nano-titanium dioxide, 20 g of KH-560, and 500 mL of anhydrous ethanol are added to a three-necked flask and stirred. The temperature of the three-necked flask is raised to 45° C., 100 mL of a 2 wt% sodium hydroxide aqueous solution is added to the three-necked flask, and the reaction is kept warm for 60 minutes. The temperature of the three-necked flask is lowered to room temperature, filtered, and the filter cake is washed with purified water until neutral and then dried. The filter cake is transferred to a drying oven at a temperature of 50° C. and vacuum dried to constant weight to obtain epoxy-modified titanium dioxide;

[0053] Weigh: 50 g of epoxy-modified titanium dioxide, 15 g of 3,5-di-tert-butyl-4-hydroxybenzyl alcohol, 250 mL of N,N-dimethylformamide and 5 g of triethylamine, add them into a three-necked flask and stir, raise the temperature of the three-necked flask to 80°C, keep warm and react for 4 hours, lower the temperature of the three-necked flask to room temperature, filter, wash the filter cake three times with anhydrous ethanol and then dry it, transfer the filter cake to a drying oven at a temperature of 50°C, and vacuum dry it to constant weight to obtain anti-aging modified particles.

[0054] S3, activated graphene

[0055] 4-Dimethylaminopyridine and triethylamine were mixed uniformly in a weight ratio of 1:3 to obtain a catalyst, which was set aside;

[0056] Weigh: 10 g of graphene oxide, 200 mL of N,N-dimethylformamide and 0.2 g of catalyst are added to a three-necked flask protected by nitrogen and stirred. The temperature of the three-necked flask is lowered to 3°C. 6 g of chloroacetyl chloride is added dropwise to the three-necked flask. After the addition is complete, the temperature of the three-necked flask is kept warm for 60 minutes. The temperature of the three-necked flask is raised to room temperature and kept warm for 10 hours. Filter, wash the filter cake three times with dichloromethane and then dry it. Transfer the filter cake to a drying oven at a temperature of 50°C and vacuum dry it to constant weight to obtain halogenated graphene;

[0057] Weigh: 9 g of halogenated graphene, 15 g of 3-butene-1-ol, 0.3 g of cuprous chloride and 90 mL of N,N-dimethylformamide, add them into a nitrogen-protected three-necked flask and stir, raise the temperature of the three-necked flask to 85°C, keep the reaction for 8 hours, lower the temperature of the three-necked flask to room temperature, filter, wash the filter cake three times with dichloromethane and then dry it, transfer the filter cake to a drying oven at a temperature of 50°C, and vacuum dry it to constant weight to obtain activated graphene.

[0058] S4. Preparation of polyurethane adhesive

[0059] Weigh out by weight: 90 parts of composite polyurethane, 13 parts of anti-aging modified particles, 7 parts of activated graphene, 8 parts of 3-aminopropyltriethoxysilane and 15 parts of dimethyl sulfoxide, add them into a nitrogen-protected three-necked flask and stir, raise the temperature of the three-necked flask to 50°C, keep warm and stir for 30 minutes, let it stand for degassing, and obtain a polyurethane adhesive.

[0060] Example 2

[0061] This embodiment provides a method for preparing an aging-resistant polyurethane adhesive with high bonding strength, comprising the following steps:

[0062] S1. Preparation of composite polyurethane

[0063] Under the protection of an inert gas atmosphere, 40 g of polytetrahydrofuran diol, 6 g of hydroxy silicone oil, and 40 mL of dimethyl sulfoxide were weighed and added to a three-necked flask protected by nitrogen and stirred. According to the calculated amount of NCO / OH=1.5, the calculated amount of toluene-2,3-diisocyanate was added to the three-necked flask, the temperature of the reaction system was raised to 85°C, 0.4 g of dibutyltin dilaurate as a catalyst was added to the reaction system, and the reaction was kept warm for 105 minutes. 8 g of melamine as a chain extender was added to the reaction system, and the reaction was kept warm for 70 minutes. The temperature of the reaction system was lowered to room temperature and the mixture was passed through a 100-mesh sieve to obtain a composite polyurethane.

[0064] S2. Preparation of anti-aging modified particles

[0065] Weigh: 50 g of nano-titanium dioxide, 20 g of KH-560, and 500 mL of anhydrous ethanol are added to a three-necked flask and stirred. The temperature of the three-necked flask is raised to 50° C., 100 mL of a 2.5 wt% sodium hydroxide aqueous solution is added to the three-necked flask, and the reaction is kept warm for 70 minutes. The temperature of the three-necked flask is lowered to room temperature, filtered, and the filter cake is washed with purified water until neutral and then dried. The filter cake is transferred to a drying oven at a temperature of 55° C. and vacuum dried to constant weight to obtain epoxy-modified titanium dioxide;

[0066] Weigh: 50 g of epoxy-modified titanium dioxide, 15 g of 3,5-di-tert-butyl-4-hydroxybenzyl alcohol, 250 mL of N,N-dimethylformamide and 5 g of triethylamine, add them into a three-necked flask and stir, raise the temperature of the three-necked flask to 85°C, keep warm and react for 5 hours, lower the temperature of the three-necked flask to room temperature, filter, wash the filter cake three times with anhydrous ethanol and then dry it, transfer the filter cake to a drying oven at a temperature of 55°C, and vacuum dry it to constant weight to obtain anti-aging modified particles.

[0067] S3, activated graphene

[0068] 4-Dimethylaminopyridine and triethylamine were mixed uniformly in a weight ratio of 1:3 to obtain a catalyst, which was set aside;

[0069] Weigh: 10 g of graphene oxide, 200 mL of N,N-dimethylformamide and 0.2 g of catalyst are added to a three-necked flask protected by nitrogen and stirred. The temperature of the three-necked flask is lowered to 4°C. 6 g of chloroacetyl chloride is added dropwise to the three-necked flask. After the addition is complete, the temperature of the three-necked flask is kept warm for 70 minutes. The temperature of the three-necked flask is raised to room temperature and kept warm for 11 hours. Filter, wash the filter cake three times with dichloromethane and then dry it. Transfer the filter cake to a drying oven at a temperature of 55°C and vacuum dry it to constant weight to obtain halogenated graphene;

[0070] Cuprous chloride and pyridine were mixed uniformly in a weight ratio of 3:1 to obtain cuprous chloride, which was set aside;

[0071] Weigh: 9 g of halogenated graphene, 15 g of 3-butene-1-ol, 0.3 g of cuprous chloride and 90 mL of N,N-dimethylformamide, add them into a nitrogen-protected three-necked flask and stir, raise the temperature of the three-necked flask to 90°C, keep warm and react for 9 hours, lower the temperature of the three-necked flask to room temperature, filter, wash the filter cake three times with dichloromethane and then dry it, transfer the filter cake to a drying oven at a temperature of 55°C, and vacuum dry it to constant weight to obtain activated graphene.

[0072] S4. Preparation of polyurethane adhesive

[0073] Weigh out by weight: 95 parts of composite polyurethane, 14 parts of anti-aging modified particles, 8 parts of activated graphene, 9 parts of 3-aminopropyltriethoxysilane and 17 parts of dimethyl sulfoxide, add them into a nitrogen-protected three-necked flask and stir, raise the temperature of the three-necked flask to 55° C., keep warm and stir for 40 minutes, let it stand for degassing, and obtain a polyurethane adhesive.

[0074] Example 3

[0075] This embodiment provides a method for preparing an aging-resistant polyurethane adhesive with high bonding strength, comprising the following steps:

[0076] S1. Preparation of composite polyurethane

[0077] Under the protection of an inert gas atmosphere, 40 g of polytetrahydrofuran diol, 6 g of hydroxy silicone oil, and 40 mL of dimethyl sulfoxide were weighed and added to a three-necked flask protected by nitrogen and stirred. According to the calculated amount of NCO / OH=1.5, the calculated amount of toluene-2,5-diisocyanate was added to the three-necked flask, the temperature of the reaction system was raised to 90°C, 0.4 g of dibutyltin dilaurate as a catalyst was added to the reaction system, and the reaction was kept warm for 120 minutes. 8 g of melamine as a chain extender was added to the reaction system, and the reaction was kept warm for 80 minutes. The temperature of the reaction system was lowered to room temperature and the mixture was passed through a 100-mesh sieve to obtain a composite polyurethane.

[0078] S2. Preparation of anti-aging modified particles

[0079] Weigh: 50 g of nano-titanium dioxide, 20 g of KH-560, and 500 mL of anhydrous ethanol are added to a three-necked flask and stirred. The temperature of the three-necked flask is raised to 55° C., 100 mL of a 3 wt% sodium hydroxide aqueous solution is added to the three-necked flask, and the reaction is kept warm for 80 minutes. The temperature of the three-necked flask is lowered to room temperature, filtered, and the filter cake is washed with purified water until neutral and then dried. The filter cake is transferred to a drying oven at a temperature of 60° C. and vacuum dried to constant weight to obtain epoxy-modified titanium dioxide;

[0080] Weigh: 50 g of epoxy-modified titanium dioxide, 15 g of 3,5-di-tert-butyl-4-hydroxybenzyl alcohol, 250 mL of N,N-dimethylformamide and 5 g of triethylamine, add them into a three-necked flask and stir, raise the temperature of the three-necked flask to 90°C, keep warm and react for 6 hours, lower the temperature of the three-necked flask to room temperature, filter, wash the filter cake three times with anhydrous ethanol and then dry it, transfer the filter cake to a drying oven at a temperature of 60°C, and vacuum dry it to constant weight to obtain anti-aging modified particles.

[0081] S3, activated graphene

[0082] 4-Dimethylaminopyridine and triethylamine were mixed uniformly in a weight ratio of 1:3 to obtain a catalyst, which was set aside;

[0083] Weigh: 10 g of graphene oxide, 200 mL of N,N-dimethylformamide and 0.2 g of catalyst are added to a three-necked flask protected by nitrogen and stirred. The temperature of the three-necked flask is lowered to 5°C. 6 g of chloroacetyl chloride is added dropwise to the three-necked flask. After the addition is complete, the temperature of the three-necked flask is kept warm for 80 minutes. The temperature of the three-necked flask is raised to room temperature and kept warm for 12 hours. The filter cake is washed three times with dichloromethane and then dried. The filter cake is transferred to a drying oven at a temperature of 60°C and vacuum dried to constant weight to obtain halogenated graphene;

[0084] Cuprous chloride and pyridine were mixed uniformly in a weight ratio of 3:1 to obtain cuprous chloride, which was set aside;

[0085] Weigh: 9 g of halogenated graphene, 15 g of 3-butene-1-ol, 0.3 g of cuprous chloride and 90 mL of N,N-dimethylformamide, add them into a nitrogen-protected three-necked flask and stir, raise the temperature of the three-necked flask to 95°C, keep the reaction for 10 hours, lower the temperature of the three-necked flask to room temperature, filter, wash the filter cake three times with dichloromethane and then dry it, transfer the filter cake to a drying oven at a temperature of 60°C, and vacuum dry it to constant weight to obtain activated graphene.

[0086] S4. Preparation of polyurethane adhesive

[0087] Weigh out by weight: 100 parts of composite polyurethane, 15 parts of anti-aging modified particles, 9 parts of activated graphene, 10 parts of 3-aminopropyltriethoxysilane and 20 parts of dimethyl sulfoxide, add them into a nitrogen-protected three-necked flask and stir, raise the temperature of the three-necked flask to 60°C, keep stirring for 50 minutes, let it stand for degassing, and obtain a polyurethane adhesive.

[0088] Comparative Example 1

[0089] The difference between this comparative example and Example 3 is that the melamine in step S1 is replaced by an equal molar amount of trimethylolethane.

[0090] Comparative Example 2

[0091] The difference between this comparative example and Example 3 is that step S2 is eliminated, and the anti-aging modified particles in step S4 are replaced by an equal amount of a mixture of nano-titanium dioxide and 3,5-di-tert-butyl-4-hydroxybenzyl alcohol in step S2 in a ratio of 10 g:3 g.

[0092] Comparative Example 3

[0093] The difference between this comparative example and Example 3 is that step S3 is eliminated, and the activated graphene in step S4 is replaced by an equal amount of graphene oxide in step S3.

[0094] Performance testing:

[0095] The peel strengths of the polyurethane adhesives prepared in Examples 1-3 and Comparative Examples 1-3 were measured with reference to the standard GB / T 2790-1995 "Test method for 180-degree peel strength of adhesives - Flexible material to rigid material";

[0096] The elongation at break of the cured polyurethane adhesive films prepared in Examples 1-3 and Comparative Examples 1-3 was measured with reference to the standard GB / T 1040.1-2018 “Determination of tensile properties of plastics Part 1: General principles”;

[0097] The polyurethane adhesive bonding samples and cured films prepared in Examples 1-3 and Comparative Examples 1-3 were placed in a constant temperature and humidity chamber at 65°C and 85% humidity for 7 days. The elongation at break of the cured films was measured according to the formula Determine the moisture and heat resistance retention rate of the sample, where F1 is the peel strength of the sample after constant temperature and humidity treatment, and F0 is the peel strength of the sample before constant temperature and humidity treatment;

[0098] The polyurethane adhesive bonding samples and cured films prepared in Examples 1-3 and Comparative Examples 1-3 were placed in an oven at 60°C for UV irradiation for 24 hours, and the elongation at break of the cured films was measured according to the formula Determine the UV resistance retention rate of the sample, where F2 is the peel strength of the sample after UV irradiation treatment, and F0 is the peel strength of the sample before UV irradiation treatment;

[0099] The specific test results are shown in Table 1 below.

[0100] Table 1-Performance test data of the sample

[0101]

[0102]

[0103] Data Analysis:

[0104] A comparative analysis of the data in Table 1 above shows that the peel strength of the polyurethane adhesive prepared by the present invention reaches 163.7 kN / m, and the elongation at break reaches 328.4%. After wet heat aging, the wet heat resistance retention rate reaches 98.8%, and the elongation at break reaches 317.2%. After UV aging, the UV resistance retention rate reaches 97.1%, and the elongation at break reaches 314.0%. All performance test data are better than those of the comparative example, indicating that the present invention enhances and modifies the composite polyurethane by anti-aging modified particles, activated graphene and 3-aminopropyltriethoxysilane, which not only effectively improves the bonding strength and tensile properties of the polyurethane adhesive, but also improves its wet heat aging and UV aging resistance.

[0105] The above contents are merely examples and explanations of the structure of the present invention. Those skilled in the art may make various modifications or additions to the described specific embodiments or replace them in a similar manner. As long as they do not deviate from the structure of the invention or exceed the scope defined by the claims, they shall fall within the scope of protection of the present invention.

[0106] Throughout this specification, references to terms such as "one embodiment," "example," or "specific example" indicate that the specific features, structures, materials, or characteristics described in conjunction with that embodiment or example are included in at least one embodiment or example of the present invention. In this specification, schematic representations of these terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

[0107] The preferred embodiments of the present invention disclosed above are intended only to help illustrate the present invention. These preferred embodiments do not exhaustively describe all details, nor do they limit the present invention to specific embodiments. Obviously, many modifications and variations are possible based on the contents of this specification. These embodiments are selected and described in detail in this specification to better explain the principles and practical applications of the present invention, thereby enabling those skilled in the art to better understand and utilize the present invention. The present invention is limited only by the claims and their full scope and equivalents.

Claims

1. A high bonding strength, aging-resistant polyurethane adhesive, characterized in that: The invention comprises the following components in parts by weight: 90-100 parts of composite polyurethane, 13-15 parts of anti-aging modified particles, 7-9 parts of activated graphene, 8-10 parts of 3-aminopropyltriethoxysilane and 15-20 parts of dimethyl sulfoxide; The preparation method of the composite polyurethane comprises: mixing polytetramethylene glycol, hydroxy silicone oil, diisocyanate and dimethyl sulfoxide under the protection of an inert gas atmosphere, raising the temperature of the reaction system to 80-90° C., adding a catalyst to the reaction system, keeping the temperature for reaction for 90-120 minutes, adding a chain extender to the reaction system, keeping the temperature for reaction for 60-80 minutes, and post-treating to obtain the composite polyurethane, wherein the chain extender is melamine; The preparation method of the anti-aging modified particles comprises: mixing epoxy-modified titanium dioxide, 3,5-di-tert-butyl-4-hydroxybenzyl alcohol, N,N-dimethylformamide and a catalyst, raising the temperature of the reaction system to 80-90° C., keeping the temperature for reaction for 4-6 hours, and post-treating to obtain the anti-aging modified particles; The preparation method of epoxy-modified titanium dioxide is as follows: nano-titanium dioxide, KH-560 and anhydrous ethanol are mixed, the temperature of the reaction system is raised to 45-55°C, a catalyst is added to the reaction system, the reaction is kept warm for 60-80 minutes, and post-processed to obtain epoxy-modified titanium dioxide; Activated graphene is obtained by the following steps: A1. Under an inert gas atmosphere, graphene oxide, N,N-dimethylformamide, and a catalyst are mixed, the temperature of the reaction system is lowered to 3-5°C, chloroacetyl chloride is added dropwise to the reaction system, and after the addition is complete, the reaction is kept warm for 60-80 minutes, the temperature of the reaction system is raised to room temperature, the reaction is kept warm for 10-12 hours, and post-processed to obtain halogenated graphene; A2. Under an inert gas atmosphere, halogenated graphene, 3-butene-1-ol, a catalyst, and N,N-dimethylformamide are mixed, the reaction system temperature is raised to 85-95°C, the reaction is kept warm for 8-10 hours, and post-processed to obtain activated graphene.

2. The aging-resistant polyurethane adhesive with high bonding strength according to claim 1, characterized in that: The amount ratio of the polytetrahydrofuran diol, hydroxy silicone oil, dimethyl sulfoxide, catalyst and chain extender is 20g:3g:20mL:0.2g:4g, the catalyst is dibutyltin dilaurate, the diisocyanate is any one of isophorone diisocyanate and toluene diisocyanate, and the amount of the diisocyanate is calculated according to NCO / OH=1.5, wherein the hydroxyl group is the molar amount of the hydroxyl group in the molecules of the polytetrahydrofuran diol and the hydroxy silicone oil. The post-processing includes: after the reaction is completed, the temperature of the reaction system is reduced to room temperature, and the mixture is passed through a 100-mesh sieve to obtain a composite polyurethane.

3. The aging-resistant polyurethane adhesive with high bonding strength according to claim 1, characterized in that: The epoxy-modified titanium dioxide, 3,5-di-tert-butyl-4-hydroxybenzyl alcohol, N,N-dimethylformamide and catalyst are used in a ratio of 10 g:3 g:50 mL:1 g, and the catalyst is triethylamine. The post-treatment includes: after the reaction is completed, lowering the temperature of the reaction system to room temperature, filtering, washing the filter cake three times with anhydrous ethanol and then drying it, transferring the filter cake to a drying oven at a temperature of 50-60° C., and vacuum drying to constant weight to obtain anti-aging modified particles.

4. The aging-resistant polyurethane adhesive with high bonding strength according to claim 1, characterized in that: The nano-titanium dioxide, KH-560, anhydrous ethanol and catalyst are used in a ratio of 5g:2g:50mL:10mL, and the catalyst is a 2-3wt% sodium hydroxide aqueous solution. The post-treatment includes: after the reaction is completed, the temperature of the reaction system is lowered to room temperature, filtration is performed, the filter cake is washed with purified water until it is neutral and then dried, and the filter cake is transferred to a drying oven at a temperature of 50-60°C and vacuum dried to constant weight to obtain epoxy-modified titanium dioxide.

5. The aging-resistant polyurethane adhesive with high bonding strength according to claim 1, characterized in that: In step A1, the amount ratio of the graphene oxide, N,N-dimethylformamide, catalyst and chloroacetyl chloride is 5g:100mL:0.1g:3g, the catalyst is composed of 4-dimethylaminopyridine and triethylamine in a weight ratio of 1:3, and the post-treatment includes: after the reaction is completed, filtering, washing the filter cake three times with dichloromethane and then drying, transferring the filter cake to a drying oven at a temperature of 50-60°C, and vacuum drying to constant weight to obtain halogenated graphene; in step A2, the amount ratio of the halogenated graphene, 3-butene-1-ol, catalyst and N,N-dimethylformamide is 3g:5g:0.1g:30mL, the catalyst is cuprous chloride, and the post-treatment includes: after the reaction is completed, lowering the temperature of the reaction system to room temperature, filtering, washing the filter cake three times with dichloromethane and then drying, transferring the filter cake to a drying oven at a temperature of 50-60°C, and vacuum drying to constant weight to obtain activated graphene.

6. A method for preparing an aging-resistant polyurethane adhesive with high bonding strength according to any one of claims 1 to 5, characterized in that: The preparation method of the high-bonding-strength aging-resistant polyurethane adhesive comprises the following steps: uniformly mixing composite polyurethane, aging-resistant modified particles, activated graphene, 3-aminopropyltriethoxysilane and dimethyl sulfoxide under the protection of an inert gas atmosphere to obtain the polyurethane adhesive.

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