High-strength cold vulcanized adhesive and preparation method thereof

Abstract

This application relates to the field of adhesive technology, specifically disclosing a high-strength cold-curing adhesive and its preparation method. The adhesive comprises the following components in parts by weight: 80-120 parts chloroprene rubber, 5-10 parts magnesium oxide, 3-6 parts zinc oxide, 1-3 parts antioxidant, 6-12 parts tackifying resin, 3-8 parts modified silica, and a mixed solvent. The amount of mixed solvent is such that the solid content of the adhesive is 15-25%. This invention first grafts a polymer structure containing lauryl acrylate flexible segments and polyethylene glycol flexible segments with local crosslinking onto the surface of methacryloyl silica. Then, lauryl acrylate and a reactive hindered phenolic antioxidant are further introduced for graft polymerization. The resulting modified silica improves the dispersion and interfacial bonding of inorganic particles in the chloroprene rubber, and the reactive antioxidant is fixed in the grafted layer through polymerization, which helps reduce its migration and loss. The prepared adhesive can better maintain high strength while enhancing its toughness.

Description

Technical Field

[0001] This application relates to the field of adhesive technology, specifically to a high-strength cold-curing adhesive and its preparation method. Background Technology

[0002] Cold vulcanizing adhesives are a type of industrial adhesive that can complete vulcanization, crosslinking, and curing at room temperature, without the need for high-temperature, high-pressure vulcanization equipment. They primarily use elastomers such as chloroprene rubber and natural rubber as raw materials, with some products being two-component systems. Curing is triggered by a chemical reaction through the mixing of the main agent and the curing agent. They are mainly used for bonding and repairing materials such as rubber to rubber, rubber to metal, and rubber to fabrics. They are widely used in conveyor belt joints and repairs, roller coating, and tire repair. Relying on the crosslinked network structure formed at room temperature, they achieve a tight bond between the adhesive layer and the substrate, making them an important adhesive material that replaces traditional hot vulcanization processes and enables rapid on-site construction.

[0003] The most prominent advantages of cold-cured adhesives are their ease of application and cost-effectiveness. Their room-temperature curing characteristic eliminates the need for large equipment such as vulcanizing machines and heating / pressurizing devices, significantly reducing equipment and energy costs. They are particularly suitable for on-site repairs in environments without large equipment, such as in the field or underground, enabling rapid troubleshooting and minimizing downtime. Simultaneously, the adhesive layer combines elasticity and bonding strength, possessing certain wear resistance, oil resistance, and aging resistance, meeting the bonding and usage requirements of most medium- and light-load conditions. In terms of timeliness and overall cost, they are significantly superior to hot-curing processes.

[0004] However, due to limitations in room temperature curing rate and on-site construction conditions, the degree of cross-linking and interfacial bonding stability of some cold bonding systems may still be insufficient. Under heavy load, impact and repeated bending conditions, fatigue cracking or interfacial peeling may easily occur, and their bonding durability still needs to be improved.

[0005] Currently, mechanical strength and aging resistance can be improved by adding nano-reinforcing materials such as graphene and silicon dioxide. However, nanomaterials have a large specific surface area and high surface energy, making them prone to aggregation. Furthermore, the addition of nanoparticles significantly increases the viscosity of the system, leading to poorer leveling properties and reduced wetting ability of the adhesive.

[0006] Therefore, how to improve bond strength and durability while taking into account construction rheology and interfacial peel resistance has become a problem that needs to be solved in this field. Summary of the Invention

[0007] Rigid nanoparticles, when insufficiently dispersed or lacking interfacial compatibility, may induce localized interfacial stress concentration, leading to a significant decrease in adhesive peel strength, impact toughness, and dynamic fatigue performance. Furthermore, nanoparticles are prone to aggregation, making dispersion difficult, and the physical interface with the rubber matrix easily becomes a weak point during aging. While conventional silane coupling agent treatment can improve particle dispersion and interfacial compatibility, it still has certain limitations in simultaneously providing interfacial flexible buffering and long-term antioxidant protection.

[0008] This invention first involves grafting lauryl acrylate and polyethylene glycol dimethacrylate onto the surface of methacryloylated silica to obtain grafted silica containing flexible long chains and locally cross-linked structures. Subsequently, based on the grafted structure, lauryl acrylate and a reactive hindered phenolic antioxidant are further introduced for further grafting polymerization.

[0009] Lauryl acrylate and reactive hindered phenolic antioxidants continue to participate in polymerization mainly on the surface of particles that have already formed grafted structures, thereby giving the resulting polymer grafted layer a compositional gradient tendency that transitions from a flexible buffer structure close to the silica core to a structure containing reactive antioxidants.

[0010] The flexible segments of lauryl acrylate and polyethylene glycol near the silica core, along with the locally cross-linked structure, help alleviate the abrupt change in rigidity and localized stress concentration between the inorganic particles and the chloroprene rubber matrix. The subsequently introduced reactive hindered phenolic antioxidant is polymerized and fixed in the grafted layer, which helps reduce its migration and loss, and provides more durable antioxidant protection near the particle-rubber interface. This stepwise grafted structure gives the modified silica the functions of inorganic reinforcement, flexible interface buffering, and antioxidant properties. The grafted polymer layer also improves the interfacial compatibility between silica and chloroprene rubber, reducing the tendency for particle aggregation.

[0011] In a first aspect, this application provides a high-strength cold-cured adhesive comprising the following components in parts by weight: 80-120 parts of chloroprene rubber, 5-10 parts of magnesium oxide, 3-6 parts of zinc oxide, 1-3 parts of antioxidant, 6-12 parts of tackifying resin, 3-8 parts of modified silica, and a mixed solvent, wherein the amount of the mixed solvent is such that the solid content of the adhesive is 15-25%.

[0012] The modified silica is obtained by first modifying the surface of nano-silica with γ-methacryloxypropyltrimethoxysilane to obtain methacrylated silica; then, the methacrylated silica is used as a matrix for continuous two-stage free radical polymerization. The monomers used in the first stage polymerization include lauryl acrylate and polyethylene glycol dimethacrylate, and the monomers used in the second stage polymerization include lauryl acrylate and 2-(2-hydroxy-3-tert-butyl-5-methylbenzyl)-4-methyl-6-tert-butylphenyl acrylate.

[0013] Furthermore, the antioxidant is antioxidant RD.

[0014] Furthermore, the tackifying resin is tert-butylphenolic resin.

[0015] Furthermore, the mixed solvent is a mixture of toluene, ethyl acetate, and 120# gasoline in a volume ratio of 4:3-4:3-4.

[0016] Furthermore, the method for preparing the modified silica includes the following steps: X1. Disperse nano-silica in a 95% ethanol aqueous solution to obtain a nano-silica dispersion; add γ-methacryloxypropyltrimethoxysilane to a 95% ethanol aqueous solution, adjust the pH to 4.0-5.0 with glacial acetic acid, and stir for 20-60 min for pre-hydrolysis; add the pre-hydrolyzed solution to the nano-silica dispersion, heat and stir for 4-8 h, and after the reaction is completed, perform solid-liquid separation, washing and drying to obtain methacrylated silica; X2. Disperse methacrylated silica in toluene and heat to 75-85℃ under nitrogen protection; mix lauryl acrylate, polyethylene glycol dimethacrylate, benzoyl peroxide and toluene evenly to obtain a first mixture; add the first mixture dropwise to the methacrylated silica dispersion over 1.5-3 hours; after the addition is complete, continue to keep the reaction at the temperature for 0.5-1.5 hours to obtain the first stage reaction solution; X3. Lauryl acrylate, 2-(2-hydroxy-3-tert-butyl-5-methylbenzyl)-4-methyl-6-tert-butylphenyl acrylate, benzoyl peroxide and toluene are mixed evenly to obtain a second mixture. The second mixture is added dropwise to the first stage reaction solution over 1.5-3 hours, with the temperature controlled at 75-85℃ during the addition. After the addition is complete, the reaction is continued at this temperature for 1-3 hours. After the reaction is completed, the mixture is cooled to room temperature, and solid-liquid separation, washing, drying and grinding are performed to obtain modified silica.

[0017] Furthermore, the mass ratio of the nano-silica to the aqueous ethanol solution and γ-methacryloyloxypropyltrimethoxysilane is 5:80-150:1.5-2.5.

[0018] Furthermore, the temperature range for heating in step X1 is 65-75℃.

[0019] Furthermore, in step X2, the mass ratio of methacryloyl silica to toluene, lauryl acrylate, polyethylene glycol dimethacrylate, and benzoyl peroxide is 5:80-120:1.5-4:0.1-0.3:0.02-0.05.

[0020] Furthermore, in step X3, the mass ratio of lauryl acrylate, 2-(2-hydroxy-3-tert-butyl-5-methylbenzyl)-4-methyl-6-tert-butylphenyl acrylate, benzoyl peroxide, and toluene in the second mixture is 0.9:0.3-0.8:0.02-0.05:15-25; and the mass ratio of the second mixture to the first stage reaction solution is 1:3-8.

[0021] Secondly, the present invention provides a method for preparing a high-strength cold-curing adhesive, comprising the following steps: S1. Mix chloroprene rubber with magnesium oxide, zinc oxide and antioxidant for 4-8 minutes, then add modified silica and continue mixing for 4-8 minutes to obtain the compound. S2. After cutting the compounded rubber into small pieces, add some of the mixed solvent, stir evenly, add the tackifying resin, continue to mix evenly, add the remaining mixed solvent, and adjust the solid content to 15-25% to obtain the adhesive.

[0022] Thirdly, the present invention provides a method for using a high-strength cold-curing adhesive, wherein the adhesive and the hardener are mixed at a mass ratio of 100:5-8 and then applied to the surfaces to be bonded, followed by bonding, pressing, and curing.

[0023] Compared with the prior art, the beneficial effects of this application are at least as follows: 1. This invention incorporates modified silica into an adhesive. The flexible segments of lauryl acrylate and polyethylene glycol near the silica core, along with the locally cross-linked structure, help mitigate abrupt changes in rigidity and localized stress concentration between the inorganic particles and the chloroprene rubber matrix. The subsequently introduced reactive hindered phenolic antioxidant is polymerized and fixed in the graft layer, reducing its migration and loss, and providing more durable antioxidant protection near the particle-rubber interface. This stepwise grafting structure endows the modified silica with inorganic reinforcement, flexible interface buffering, and antioxidant functions.

[0024] 2. 2-(2-hydroxy-3-tert-butyl-5-methylbenzyl)-4-methyl-6-tert-butylphenyl acrylate, as an antioxidant, is chemically bonded into the polymer graft layer on the silica surface to enhance long-term antioxidant properties. Polyethylene glycol dimethacrylate, as a bifunctional crosslinking monomer containing flexible polyethylene glycol segments, can form a crosslinked structure in the grafted polymer; lauryl acrylate introduces long alkyl flexible segments. Together, they alleviate the interfacial rigidity abruptness caused by inorganic silica, improving the interfacial peel resistance of the adhesive layer.

[0025] 3. The polymer graft layer on the surface of modified silica can provide certain steric hindrance and improve its interfacial compatibility with the chloroprene rubber matrix, thereby reducing the agglomeration tendency of nano silica and improving its dispersion stability. Detailed Implementation

[0026] The various embodiments or implementation schemes in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments.

[0027] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "illustrative embodiment," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with an embodiment or example is included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above 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 one or more embodiments or examples.

[0028] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this application, "multiple" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0029] In this specification, unless otherwise specified, "parts" refers to "parts by weight".

[0030] The following describes embodiments of this application. The embodiments described below are exemplary and are only used to explain this application, and should not be construed as limiting this application. Where specific techniques or conditions are not specified in the embodiments, they are performed according to the techniques or conditions described in the literature in this field or according to the product instructions. Reagents or instruments used, unless otherwise specified, are all conventional products that can be obtained commercially.

[0031] Nano-silica, hydrophilic, particle size: 10-20nm, specific surface area: 200m² 2 / g.

[0032] 2-(2-hydroxy-3-tert-butyl-5-methylbenzyl)-4-methyl-6-tert-butylphenyl acrylate, CAS No.: 61167-58-6.

[0033] Polyethylene glycol dimethacrylate, number average molecular weight: 400.

[0034] Neoprene rubber, model: CR244.

[0035] Triphenylmethane triisocyanate hardener is an ethyl acetate solution of triphenylmethane triisocyanate with an active ingredient content of 27 wt%.

[0036] Example 1 A method for preparing a high-strength cold-curing adhesive comprises the following steps: S1. Mix 100 parts of chloroprene rubber with 8 parts of magnesium oxide, 5 parts of zinc oxide and 2 parts of antioxidant RD for 5 minutes, then add 3 parts of modified silica and continue mixing for 5 minutes to obtain the compound. S2. After cutting the compounded rubber into small pieces, add 1 / 3 of the mixed solvent, which is a mixture of toluene, ethyl acetate and 120# gasoline in a volume ratio of 4:3:3. After stirring evenly, add 10 parts of tert-butylphenol resin, continue to mix evenly, and then add the remaining mixed solvent to make the solid content 20% to obtain the adhesive.

[0037] The method for preparing the modified silica comprises the following steps: X1. Add 5 parts of nano-silica to 80 parts of 95% ethanol aqueous solution and ultrasonically disperse for 30 min to obtain nano-silica dispersion; add 2 parts of γ-methacryloxypropyltrimethoxysilane to 20 parts of 95% ethanol aqueous solution, adjust the pH to 4.5 with glacial acetic acid, stir at room temperature for 30 min for pre-hydrolysis to obtain pre-hydrolyzed solution; slowly add the pre-hydrolyzed solution to the nano-silica dispersion, heat to 70℃ and stir for 6 h; after the reaction is completed, cool to room temperature, centrifuge, disperse with anhydrous ethanol, wash 3 times by centrifugation, and vacuum dry at 60℃ for 12 h to obtain methacrylated silica; X2. Add 5 parts of methacrylamide silica to 80 parts of anhydrous toluene, sonicate for 30 min, and heat to 78℃ under nitrogen protection; mix 2.4 parts of lauryl acrylate, 0.15 parts of polyethylene glycol dimethacrylate, 0.03 parts of benzoyl peroxide, and 20 parts of anhydrous toluene evenly to obtain the first mixture; slowly add the first mixture dropwise to the methacrylamide silica dispersion over 2 h, maintaining the reaction temperature at 78±2℃ during the dropwise addition, and continue to keep the reaction at this temperature for 1 h after the dropwise addition is complete to obtain the first stage reaction solution; X3. Mix 0.9 parts of lauryl acrylate, 0.6 parts of 2-(2-hydroxy-3-tert-butyl-5-methylbenzyl)-4-methyl-6-tert-butylphenyl acrylate, 0.03 parts of benzoyl peroxide, and 20 parts of anhydrous toluene to obtain a second mixture. Under nitrogen protection and at 78±2℃, slowly add the second mixture dropwise to the first stage reaction solution over 2 hours. The mass ratio of the second mixture to the first stage reaction solution is 1:5. After the addition is complete, continue to keep the temperature for 2 hours. After the reaction is completed, cool to room temperature, centrifuge, disperse with anhydrous toluene, wash three times by centrifugation, vacuum dry at 60℃ for 12 hours, and grind to obtain modified silica.

[0038] Example 2 It is basically the same as Example 1, except that the amount of modified silica used is 5 parts.

[0039] Example 3 It is basically the same as Example 1, except that the amount of modified silica used is 8 parts.

[0040] Comparative Example 1 The process is basically the same as in Example 1, except that 2-(2-hydroxy-3-tert-butyl-5-methylbenzyl)-4-methyl-6-tert-butylphenyl acrylate is not added to the second mixture prepared in step X3. The second mixture consists of 0.9 parts lauryl acrylate, 0.03 parts benzoyl peroxide, and 20 parts anhydrous toluene. When preparing the adhesive, 2.80 parts of modified silica were added, and 0.20 parts of free 2-(2-hydroxy-3-tert-butyl-5-methylbenzyl)-4-methyl-6-tert-butylphenyl acrylate were added.

[0041] Comparative Example 2 The process is basically the same as in Example 1, except that in step X2, 1.00 parts of methyl methacrylate and other double bond molar amounts are used to replace 2.4 parts of lauryl acrylate, and in step X3, 0.37 parts of methyl methacrylate and other double bond molar amounts are used to replace 0.9 parts of lauryl acrylate. When preparing the adhesive, the amount of modified silica added in Comparative Example 2 was 2.36 parts, so that the mass of the methacrylamide silica matrix introduced into the adhesive was basically the same as that in Example 1.

[0042] Comparative Example 3 The process is essentially the same as in Example 1, except that the order in which the functional monomers in the two stages are added is reversed: the first mixture in step X2 consists of 0.9 parts lauryl acrylate, 0.6 parts 2-(2-hydroxy-3-tert-butyl-5-methylbenzyl)-4-methyl-6-tert-butylphenyl acrylate, 0.03 parts benzoyl peroxide, and 20 parts anhydrous toluene; the second mixture in step X3 consists of 2.4 parts lauryl acrylate, 0.15 parts polyethylene glycol dimethacrylate, 0.03 parts benzoyl peroxide, and 20 parts anhydrous toluene.

[0043] Comparative Example 4 The process is basically the same as in Example 1, except that the two-stage stepwise addition is not performed. Instead, 3.3 parts of lauryl acrylate, 0.15 parts of polyethylene glycol dimethacrylate, 0.6 parts of 2-(2-hydroxy-3-tert-butyl-5-methylbenzyl)-4-methyl-6-tert-butylphenyl acrylate, 0.06 parts of benzoyl peroxide, and 40 parts of anhydrous toluene are mixed evenly. The resulting mixture is then added dropwise to a methacryloylated silica dispersion over 4 hours. After the addition is complete, the reaction is continued at the temperature for another 3 hours.

[0044] Test section 1. The adhesives prepared in the examples and comparative examples were mixed with triphenylmethane triisocyanate hardener at a mass ratio of 100:6. The bonding surfaces of the aluminum alloy plates were sanded in the same direction with 240-grit sandpaper and degreased with ethyl acetate. The bonding surfaces of the neoprene rubber sheets were sanded until the surface was uniformly rough and debris was removed. The mixed adhesives were evenly applied to different bonding surfaces, allowed to dry at room temperature for 10 minutes, and then bonded together. The bonding surfaces were then pressed together under a pressure of 0.1 MPa for 10 minutes. Timing was started from the end of the pressing process, and the adhesives were cured at room temperature for 30 minutes and 24 hours, respectively, before testing. Tensile shear strength and 180° peel strength were tested, and the test methods were in accordance with GB / T 7124-2008 "Determination of Tensile Shear Strength of Adhesives (Rigid Material to Rigid Material)" and GB / T 2790-1995 "Test Method for 180° Peel Strength of Adhesives (Flexible Material to Rigid Material)".

[0045] The tensile shear test specimens were LY12CZ aluminum alloy plates, measuring 100mm × 25mm × 1.5mm, with an overlap length of 12.5mm. The tests were conducted at a tensile speed of 10mm / min. The maximum breaking load was recorded, and the tensile shear strength (MPa) was calculated. Five parallel tests were performed for each group, and the average value was taken.

[0046] For the peel test, a 2.0 mm thick neoprene rubber sheet was used as the flexible substrate, and an LY12CZ aluminum alloy plate was used as the rigid substrate. The sample width was 25 mm, and the bonding length was 150 mm. During the test, a 180° peel was performed at a peel speed of 100 mm / min, with a peel length of not less than 125 mm. The force value within the initial 25 mm range was discarded, and the average force value of the subsequent 100 mm stable peel range was used to calculate the 180° peel strength, in kN / m. Each group underwent three parallel tests, and the average value was taken.

[0047] 2. Place the cured sample in a forced-air drying oven and age it continuously at 100℃ for 168 hours. After aging, move the sample to room temperature and adjust it for 24 hours. Then, re-measure its 180° peel strength using the same test method as above. Strength retention rate (%) = (strength after aging / initial strength after curing at room temperature for 24 hours) × 100%.

[0048] Table 1 As can be seen from Table 1, the adhesive prepared in this invention exhibits high bonding strength and peel resistance after curing for 30 minutes.

[0049] Compared to Comparative Example 1, Example 1 first forms a first-stage graft layer containing flexible segments of lauryl acrylate and locally cross-linked polyethylene glycol dimethacrylate on the surface of methacryloyl silica, and then introduces lauryl acrylate and a reactive hindered phenolic antioxidant for a second-stage grafting. The first-stage grafting structure helps to alleviate the rigidity difference between the silica inorganic core and the chloroprene rubber matrix, reducing local interfacial stress concentration; the reactive antioxidant introduced in the second stage can be polymerized into the polymer graft layer on the particle surface, reducing its migration and loss during long-term heating.

[0050] The modified silica used in Comparative Example 1 has a flexible cross-linked graft structure similar to that of Example 1, but the reactive antioxidant did not participate in the graft polymerization; instead, it was added to the main agent in a free form. Therefore, the initial tensile shear strength and 180° peel strength of Comparative Example 1 are quite similar to those of Example 1. However, during aging at 100°C, the free antioxidant is difficult to stably distribute near the silica-rubber interface and may migrate, diffuse, or be lost, resulting in a significantly lower peel strength retention rate after aging compared to Example 1. This indicates that fixing the reactive antioxidant in the polymer graft layer on the silica surface is beneficial for improving the durability of the antioxidant effect.

[0051] Comparative Example 2 replaced lauryl acrylate with methyl methacrylate in equal molar amounts of double bonds. The segments formed by methyl methacrylate are more rigid and cannot provide sufficient flexible buffering between the silica inorganic core and the chloroprene rubber matrix as effectively as the long alkyl segments of lauryl acrylate. Therefore, Comparative Example 2 still possesses certain shear strength and anti-aging properties, but its 180° peel strength and aging retention rate are lower than those of Example 1.

[0052] Comparative Example 3 used the same functional monomers and total amounts as Example 1, but reversed the two-stage grafting sequence, so that the reactive antioxidant participated in the grafting in the first stage, while the flexible segments containing the polyethylene glycol crosslinking structure were mainly formed in the second stage. This reaction sequence is not conducive to the initial establishment of a continuous flexible buffer grafting structure on the silica core surface, so its interfacial peel resistance and strength retention after thermal aging are lower than those of Example 1.

[0053] Comparative Example 4 used the same functional monomers and total amount as Example 1, but instead of adding them separately in two stages with different compositions, all functional monomers were mixed and added dropwise continuously. Different functional monomers simultaneously participated in surface grafting and solution polymerization throughout the entire dropwise addition process, making it difficult to achieve the continuous two-stage compositional distribution seen in Example 1, where flexible segments and locally cross-linked structures were introduced first, followed by the introduction of reactive hindered phenolic antioxidant structures. Therefore, although Comparative Example 4 contained flexible segments, cross-linked structures, and reactive antioxidants, the overall matching degree of the various functional structures was lower than that of Example 1.

[0054] Compared to Examples 1 and 3, Example 2 uses a different amount of modified silica. At a relatively low amount, the reinforcing, interfacial buffering, and antioxidant effects are not fully realized. However, excessively high particle content increases the system viscosity, the possibility of interparticle contact and localized agglomeration, affecting the adhesive's wetting of the substrate and the uniformity of the interfacial structure. Therefore, a higher amount of modified silica is not necessarily better; approximately 5 parts achieve a better balance between reinforcement, flexible interfacial buffering, and filler dispersion.

[0055] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application.

Claims

1. A high-strength cold-curing adhesive, characterized in that, The adhesive comprises the following components in parts by weight: 80-120 parts chloroprene rubber, 5-10 parts magnesium oxide, 3-6 parts zinc oxide, 1-3 parts antioxidant, 6-12 parts tackifying resin, 3-8 parts modified silica, and a mixed solvent, wherein the amount of mixed solvent is such that the solid content of the adhesive is 15-25%. The method for preparing the modified silica includes the following steps: X1. Disperse nano-silica in a 95% ethanol aqueous solution to obtain a nano-silica dispersion; add γ-methacryloxypropyltrimethoxysilane to a 95% ethanol aqueous solution, adjust the pH to 4.0-5.0 with glacial acetic acid, and stir for 20-60 min for pre-hydrolysis; add the pre-hydrolyzed solution to the nano-silica dispersion, heat and stir for 4-8 h, and after the reaction is completed, perform solid-liquid separation, washing and drying to obtain methacrylated silica; X2. Disperse methacrylated silica in toluene and heat to 75-85℃ under nitrogen protection; mix lauryl acrylate, polyethylene glycol dimethacrylate, benzoyl peroxide and toluene evenly to obtain a first mixture; add the first mixture dropwise to the methacrylated silica dispersion over 1.5-3 hours; after the addition is complete, continue to keep the reaction at the temperature for 0.5-1.5 hours to obtain the first stage reaction solution; X3. Lauryl acrylate, 2-(2-hydroxy-3-tert-butyl-5-methylbenzyl)-4-methyl-6-tert-butylphenyl acrylate, benzoyl peroxide, and toluene are mixed evenly to obtain a second mixture. The second mixture is added dropwise to the first stage reaction solution over 1.5-3 hours, with the temperature controlled at 75-85℃ during the addition. After the addition is complete, the reaction is continued at this temperature for 1-3 hours. After the reaction is completed, the mixture is cooled to room temperature, and then subjected to solid-liquid separation, washing, drying, and grinding to obtain modified silica. The mixed solvent is a mixture of toluene, ethyl acetate, and 120# gasoline in a volume ratio of 4:3-4:3-4.

2. The high-strength cold-curing adhesive as described in claim 1, characterized in that, The antioxidant is antioxidant RD.

3. The high-strength cold-curing adhesive as described in claim 1, characterized in that, The tackifying resin is tert-butylphenolic resin.

4. The high-strength cold-curing adhesive as described in claim 1, characterized in that, The mass ratio of the nano-silica to the aqueous ethanol solution and γ-methacryloyloxypropyltrimethoxysilane is 5:80-150:1.5-2.

5.

5. The high-strength cold-curing adhesive as described in claim 1, characterized in that, The temperature range for heating in step X1 is 65-75℃.

6. The high-strength cold-curing adhesive as described in claim 1, characterized in that, In step X2, the mass ratio of methacryloyl silica to toluene, lauryl acrylate, polyethylene glycol dimethacrylate, and benzoyl peroxide is 5:80-120:1.5-4:0.1-0.3:0.02-0.

05.

7. The high-strength cold-curing adhesive as described in claim 1, characterized in that, In step X3, the mass ratio of lauryl acrylate, 2-(2-hydroxy-3-tert-butyl-5-methylbenzyl)-4-methyl-6-tert-butylphenyl acrylate, benzoyl peroxide, and toluene in the second mixture is 0.9:0.3-0.8:0.02-0.05:15-25; the mass ratio of the second mixture to the first stage reaction solution is 1:3-8.

8. The method for preparing the high-strength cold-curing adhesive according to any one of claims 1-7, characterized in that, Includes the following steps: S1. Mix chloroprene rubber with magnesium oxide, zinc oxide and antioxidant for 4-8 minutes, then add modified silica and continue mixing for 4-8 minutes to obtain the compound. S2. After cutting the compounded rubber into small pieces, add some of the mixed solvent, stir evenly, add the tackifying resin, continue to mix evenly, add the remaining mixed solvent, and adjust the solid content to 15-25% to obtain the adhesive.

Images