High-strength acrylate structural adhesive as well as preparation method and application thereof

Abstract

The invention relates to a high-strength acrylate structural adhesive as well as a preparation method and application thereof, in particular to an adhesive suitable for structural bonding in the fields of composite materials, stylus and electrical assembly, interior and exterior decoration of vehicle bodies and the like. The high-strength acrylate structural adhesive is composed of a component A (including hyperbranched multifunctional acrylate resin, a first acrylic monomer, a flexibilizer, an accelerant and a first stabilizer) and a component B (including peroxide, a second acrylic monomer, a plasticizer and a second stabilizer). The hyperbranched multifunctional acrylate resin is prepared from heat-resistant aliphatic hyperbranched polyester containing terminal hydroxyl and an acrylic acid reagent. Through the synergistic effect of the hyperbranched multifunctional acrylate resin, the acrylic monomer, the peroxide and other components, the prepared structural adhesive is high in bonding strength, high in toughness and good in heat resistance and weather resistance.

Description

Technical Field

[0001] This invention relates to the field of structural adhesives, and in particular to a high-strength acrylate structural adhesive, its preparation method, and its applications. Background Technology

[0002] Structural bonding, as an efficient and reliable method of material joining, plays a crucial role in modern industrial assembly fields (such as automobile manufacturing, rail transportation, electronics, aerospace, and new energy equipment), enabling effective bonding between components of different materials and meeting increasingly stringent performance requirements. Currently, a wide variety of adhesives are used in structural bonding, among which epoxy resin adhesives, acrylic adhesives, and polyurethane adhesives are the most common.

[0003] Each of the aforementioned structural adhesives has its own characteristics. Epoxy structural adhesives are widely used due to their excellent bonding strength, good chemical resistance, and electrical insulation. However, their generally slow curing speed often requires heating (such as high-temperature baking) to achieve full curing, which limits their application in scenarios where production efficiency is paramount. Polyurethane structural adhesives, on the other hand, are known for their good toughness, good adhesion to various substrates, and moderate cost. However, their overall mechanical strength (especially shear strength) is relatively limited, and they are insufficient in heat resistance (strength under long-term high-temperature conditions) and weather resistance (UV aging and damp heat aging performance), limiting their application in harsh environments.

[0004] In contrast, acrylic structural adhesives exhibit significant overall advantages. They typically possess extremely high bond strength (especially tensile and shear strength), can cure rapidly at room temperature, significantly shortening processing cycles, while also exhibiting good heat and weather resistance. These advantages make acrylic structural adhesives widely applicable in situations requiring high efficiency, strength, and durability, such as rapid on-site repair of large components, high-speed assembly on automated production lines, sealing and fixing of outdoor equipment, and connections of some lightweight structural components.

[0005] However, despite the numerous advantages of acrylic structural adhesives, existing technologies still have significant limitations, becoming a bottleneck restricting their further expansion into high-end applications. The core issue lies in the difficulty of achieving a balance in their mechanical properties: namely, it is difficult to simultaneously achieve high strength and excellent toughness. Specifically, in formula design pursuing ultra-high strength and heat resistance, it is often necessary to increase the crosslinking density or introduce rigid fillers. However, this inevitably leads to brittleness of the adhesive layer, significantly reducing its impact resistance and crack propagation resistance (i.e., toughness), making it prone to brittle failure in areas subjected to dynamic loads or stress concentrations. Conversely, if toughening components are added to improve toughness, it often comes at the cost of sacrificing some initial strength or modulus, and the amount of traditional elastic rubber phase added is limited by compatibility, thus restricting the application of existing acrylic structural adhesives under extreme conditions (such as high load, high impact, and wide temperature range variations).

[0006] Therefore, how to break through this technical barrier and develop a new acrylic structural adhesive formulation or modification technology that can maintain the inherent advantages of high strength, fast curing and good weather resistance of acrylic adhesives, while significantly improving their fracture toughness and impact resistance, and achieving synergistic optimization of strength and toughness, is a key technical problem that urgently needs to be solved in this field, and has important theoretical significance and practical application value. Summary of the Invention

[0007] To address the problems of limited compatibility, difficulty in achieving both toughness and strength, and poor weather resistance in existing acrylic structural adhesives, this application provides a high-strength acrylic structural adhesive and its preparation method.

[0008] In a first aspect, the present invention provides a high-strength acrylic structural adhesive, the structural adhesive comprising component A and component B; Component A includes hyperbranched multifunctional acrylate resin, a first acrylic monomer, a toughening agent, an accelerator, and a first stabilizer; Component B includes peroxide, a second acrylic monomer, a plasticizer, and a second stabilizer; The hyperbranched multifunctional acrylate resin is prepared by using heat-resistant aliphatic hyperbranched polyester with terminal hydroxyl groups and acrylic reagent through methods such as direct esterification, acyl chloride esterification, transesterification or addition esterification. The heat-resistant aliphatic hyperbranched polyester with terminal hydroxyl groups has a hydroxyl value of 500~550 mgKOH / g and a molecular weight of 600~3000 g / mol.

[0009] Preferably, the volume ratio of component A to component B is 10:1.

[0010] Preferably, the first acrylic monomer and the second acrylic monomer are each selected from at least one of acrylic acid, methacrylic acid, methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, butyl acrylate, butyl methacrylate, isobornyl acrylate, isobornyl methacrylate, tetrahydrofuran acrylate, tetrahydrofuran methacrylate, cyclotrimethylolpropane formal acrylate, hydroxyethyl acrylate, hydroxyethyl methacrylate, acryloylmorpholine, trimethylcyclohexyl acrylate, p-tert-butylcyclohexyl acrylate, dicyclopentyl acrylate, dimethyl cyclohexane diacrylate, ethylene glycol dimethacrylate, diethylene glycol dimethacrylate, butanediol dimethacrylate, hexanediol diacrylate, triethylene glycol diacrylate, and tripropylene glycol diacrylate. The toughening agent includes at least one of nitrile rubber, polysulfide rubber, polybutadiene rubber, styrene-butadiene rubber, styrene, phthalate, ABS resin, polyvinyl acetate, and methyl methacrylate-butadiene-styrene terpolymer. The accelerator includes at least one selected from tertiary amines, thiourea derivatives, and metal salts; The first stabilizer and the second stabilizer are each selected from at least one of p-methoxyphenol, EDTA-4Na, hydroquinone, p-phenol, p-benzoquinone, and 2,6-di-tert-butyl-4-methylphenol.

[0011] Preferably, the peroxide is selected from at least one of benzoyl peroxide, dilauryl peroxide, methyl ethyl ketone peroxide, cyclohexanone peroxide, tert-amyl hydroperoxide, tert-butyl hydroperoxide, cumene peroxide, and dicumene peroxide; The plasticizer includes at least one of dibutyl phthalate, dioctyl phthalate, diethylene glycol phthalate, polyether N330, liquid paraffin, and petroleum resin.

[0012] Preferably, component A of the high-strength acrylate structural adhesive further includes a first additive; component B further includes a second additive and a filler. By weight, component A comprises: 20-40 parts of hyperbranched multifunctional acrylate resin, 40-65 parts of a first acrylic monomer, 10-20 parts of toughening agent, 0.1-3 parts of accelerator, 0.05-3 parts of a first stabilizer, and 0.1-3 parts of a first additive.

[0013] Component B comprises: 20-40 parts peroxide, 10-30 parts second acrylic monomer, 10-30 parts plasticizer, 0.05-3 parts second stabilizer, 5-15 parts second auxiliary agent, and 20-40 parts filler.

[0014] Preferably, the first acrylic monomer is a combination of methyl methacrylate and trimethylcyclohexyl acrylate; By weight, it includes 35 to 50 parts of methyl methacrylate and 5 to 15 parts of trimethylcyclohexyl acrylate.

[0015] Preferably, the preparation method of the hyperbranched multifunctional acrylate resin includes the following steps: Under inert gas protection, heat-resistant aliphatic hyperbranched polyester containing terminal hydroxyl groups, acrylic acid reagent and catalyst are added to a reflux apparatus, the temperature is raised to 130~150℃, refluxed for 3~6h, the reaction is stopped, and the hyperbranched multifunctional acrylate resin is obtained after purification.

[0016] Preferably, the acrylic reagent includes at least one selected from acrylic acid, methacrylic acid, acryloyl chloride, methacryloyl chloride, methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, acrylate isocyanate, and methacrylate isocyanate. The molar ratio of the heat-resistant aliphatic hyperbranched polyester containing terminal hydroxyl groups to the acrylic reagent is 1:(5~7).

[0017] Secondly, this application provides a method for preparing the high-strength acrylate structural adhesive described above, characterized by comprising the following steps: Preparation of component A: Hyperbranched multifunctional acrylate resin, first acrylic monomer, toughening agent, accelerator, first stabilizer, and first auxiliary agent are mixed and stirred evenly under vacuum conditions, and then discharged after vacuum degassing; Preparation of component B: The peroxide, second acrylic monomer, plasticizer, second stabilizer, second auxiliary agent, and filler are mixed and stirred evenly under vacuum conditions at room temperature. After vacuum degassing, the mixture is discharged. The obtained components A and B are poured into A and B tubes respectively using an automatic dispensing machine. After centrifugation to remove bubbles, the tubes are sealed to obtain high-strength acrylic structural adhesive.

[0018] Thirdly, this application provides an application of the high-strength acrylic structural adhesive described above in structural bonding in fields such as composite materials, laptop assembly, and vehicle interior and exterior trim.

[0019] The beneficial effects of this invention are as follows: The hyperbranched multifunctional acrylate resin prepared in this application possesses highly polar hydroxyl groups and ester bonds, which can effectively improve the adhesive strength of structural adhesives. It also has multiple reactive acrylate groups that can participate in the curing and crosslinking reaction, increasing the crosslinking density of the structural adhesive and resulting in high adhesive strength. The hyperbranched core structure provides better chain segment movement freedom, enhancing its ability to absorb and disperse impact energy (toughening). Simultaneously, the restricted long-range movement of chain segments and the enhanced crosslinking efficiency of the terminal multi-groups prevent flow deformation at high temperatures (heat resistance). Compared to traditional linear polyether prepolymers, it can maintain better heat resistance and resistance to damp heat aging while providing toughening. The reactive toughening characteristics of the hyperbranched multifunctional acrylate resin can also solve the problem of decreased compatibility caused by excessive addition of traditional toughening agents, providing better toughening effects and further improving the strength of structural adhesives.

[0020] This application utilizes the synergistic effect of hyperbranched multifunctional acrylate resin, acrylic monomers, peroxides, and other components to prepare a structural adhesive with high bonding strength, high toughness, and good heat and weather resistance. Detailed Implementation

[0021] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0022] To illustrate the technical solution of the present invention, specific embodiments are described below.

[0023] In a first aspect, the present invention provides a high-strength acrylic structural adhesive, the structural adhesive comprising component A and component B; Component A includes hyperbranched multifunctional acrylate resin, a first acrylic monomer, a toughening agent, an accelerator, and a first stabilizer; Component B includes peroxide, a second acrylic monomer, a plasticizer, and a second stabilizer; This application utilizes the synergistic effect of hyperbranched multifunctional acrylate resin with acrylic monomers, peroxides, and additives to prepare a structural adhesive with high bonding strength, high toughness, and good heat and weather resistance.

[0024] The hyperbranched multifunctional acrylate resin is prepared by using heat-resistant aliphatic hyperbranched polyester with terminal hydroxyl groups and acrylic reagent through methods such as direct esterification, acyl chloride esterification, transesterification or addition esterification. The heat-resistant aliphatic hyperbranched polyester with terminal hydroxyl groups has a hydroxyl value of 500~550 mgKOH / g and a molecular weight of 600~3000 g / mol.

[0025] The hyperbranched multifunctional acrylate resin prepared in this application possesses highly polar hydroxyl groups and ester bonds, which can effectively improve the adhesive strength of structural adhesives. It also has multiple reactive acrylate groups that can participate in the curing and crosslinking reaction, increasing the crosslinking density of the structural adhesive and resulting in high adhesive strength. The hyperbranched core structure provides better chain segment movement freedom, enhancing its ability to absorb and disperse impact energy (toughening). Simultaneously, the restricted long-range movement of chain segments and the enhanced crosslinking efficiency of the terminal multi-groups prevent flow deformation at high temperatures (heat resistance). Compared to traditional linear polyether prepolymers, it can maintain better heat resistance and resistance to damp heat aging while providing toughening. The reactive toughening characteristics of the hyperbranched multifunctional acrylate resin can also solve the problem of decreased compatibility caused by excessive addition of traditional toughening agents, providing better toughening effects and further improving the strength of structural adhesives.

[0026] In some embodiments of the present invention, the volume ratio of component A to component B is 10:1.

[0027] In some embodiments of the present invention, the first acrylic monomer and the second acrylic monomer are respectively selected from at least one of acrylic acid, methacrylic acid, methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, butyl acrylate, butyl methacrylate, isobornyl acrylate, tetrahydrofuran acrylate, tetrahydrofuran methacrylate, cyclotrimethylolpropane acetal acrylate, hydroxyethyl acrylate, hydroxyethyl methacrylate, isobornyl methacrylate, acryloylmorpholine, trimethylcyclohexyl acrylate, p-tert-butylcyclohexyl acrylate, dicyclopentyl acrylate, dimethyl cyclohexane diacrylate, ethylene glycol dimethacrylate, diethylene glycol dimethacrylate, butanediol dimethacrylate, hexanediol diacrylate, triethylene glycol diacrylate, and tripropylene glycol diacrylate; The toughening agent includes at least one of nitrile rubber, polysulfide rubber, polybutadiene rubber, styrene-butadiene rubber, styrene, phthalate, ABS resin, polyvinyl acetate, and methyl methacrylate-butadiene-styrene terpolymer. The accelerator includes at least one selected from tertiary amines, thiourea derivatives, and metal salts; In a specific embodiment of the present invention, the tertiary amine includes at least one of triethylamine, tripropylamine, tributylamine, and N,N-dimethyl-p-toluidine.

[0028] In some embodiments of the present invention, the first stabilizer and the second stabilizer are each selected from at least one of p-methoxyphenol, EDTA-4Na, hydroquinone, p-phenol, p-benzoquinone, and 2,6-di-tert-butyl-4-methylphenol.

[0029] In some embodiments of the present invention, the peroxide is selected from at least one of benzoyl peroxide, dilauryl peroxide, methyl ethyl ketone peroxide, cyclohexanone peroxide, tert-amyl hydroperoxide, tert-butyl hydroperoxide, cumene peroxide, and dicumene peroxide. The plasticizer includes at least one of dibutyl phthalate, dioctyl phthalate, diethylene glycol phthalate, polyether N330, liquid paraffin, and petroleum resin.

[0030] In some embodiments of the present invention, the high-strength acrylate structural adhesive component A further includes a first additive; component B further includes a second additive and a filler; By weight, component A comprises: 20-40 parts of hyperbranched multifunctional acrylate resin, such as 20, 23, 25, 27, 30, 32, 35, 37, 40 parts or any value between therewith; 40-65 parts of a first acrylic monomer, such as 40, 45, 50, 55, 60, 65 parts or any value between therewith; and 10-20 parts of a toughening agent, such as 10, 12, 14, 16, 18, 20 parts or other... Any value between them; 0.1 to 3 parts of accelerator, such as 0.1, 0.5, 1, 1.5, 2, 2.5, 3 parts or any value between them; 0.05 to 3 parts of primary stabilizer, such as 0.05, 0.1, 0.5, 1, 1.5, 2, 2.5, 3 parts or any value between them; 0.1 to 3 parts of primary adjuvant, such as 0.1, 0.5, 1, 1.5, 2, 2.5, 3 parts or any value between them.

[0031] Component B comprises: 20-40 parts of peroxide, such as 20, 23, 25, 27, 30, 32, 35, 37, 40 parts or any value between them; 10-30 parts of a second acrylic monomer, such as 10, 13, 15, 17, 20, 22, 25, 27, 30 parts or any value between them; and 10-30 parts of a plasticizer, such as 10, 13, 15, 17, 20, 22, 25, 27, 30 parts or other... Any value between them; 0.05~3 parts of second stabilizer, such as 0.05, 0.1, 0.5, 1, 1.5, 2, 2.5, 3 parts or any value between them; 5~15 parts of second adjuvant, such as 5, 7, 9, 10, 11, 12, 13, 14, 15 parts or any value between them; 20~40 parts of filler, such as 20, 23, 25, 27, 30, 32, 35, 37, 40 parts or any value between them.

[0032] In some embodiments of the present invention, the first acrylic monomer is a combination of methyl methacrylate and trimethylcyclohexyl acrylate; By weight, it includes 35 to 50 parts of methyl methacrylate, such as 30, 33, 35, 37, 40, 42, 45, 47, 50 parts or any value therein; and 5 to 15 parts of trimethylcyclohexyl acrylate, such as 5, 7, 9, 10, 11, 12, 13, 14, 15 parts or any value therein.

[0033] In some embodiments of the present invention, the filler includes at least one of reinforcing filler, flame-retardant filler, and thermally conductive filler.

[0034] The reinforcing filler includes calcium carbonate whiskers.

[0035] In some embodiments of the present invention, the additives include at least one of thixotropic agents, fluorescent agents, color-changing powders, leveling agents, wetting agents, defoamers, silane coupling agents, antioxidants, antibacterial agents, flame retardants, and fillers.

[0036] The substance includes thixotropic fumed silica.

[0037] In some embodiments of the present invention, the preparation method of the hyperbranched multifunctional acrylate resin includes the following steps: Under inert gas protection, heat-resistant aliphatic hyperbranched polyester containing terminal hydroxyl groups, acrylic acid reagent and catalyst are added to a reflux apparatus, the temperature is raised to 130~150℃, refluxed for 3~6h, the reaction is stopped, and the hyperbranched multifunctional acrylate resin is obtained after purification.

[0038] In some embodiments of the present invention, the acrylic reagent includes at least one selected from acrylic acid, methacrylic acid, acryloyl chloride, methacryloyl chloride, methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, acrylate isocyanate, and methacrylate isocyanate. The molar ratio of the heat-resistant aliphatic hyperbranched polyester containing terminal hydroxyl groups to the acrylic reagent is 1:(5~7).

[0039] In some embodiments of the present invention, the catalyst comprises one of p-toluenesulfonic acid, concentrated sulfuric acid, polyphosphoric acid, and Lewis acid; the amount of catalyst added is 0.01% of the mass of the heat-resistant aliphatic hyperbranched polyester containing terminal hydroxyl groups.

[0040] In a second aspect, the present invention also provides a method for preparing the high-strength acrylate structural adhesive, comprising the following steps: Preparation of component A: Heat-resistant aliphatic hyperbranched polyester, first acrylic monomer, toughening agent, accelerator, first stabilizer, and first auxiliary agent are mixed and stirred evenly under vacuum conditions, and then discharged after vacuum degassing; Preparation of component B: The peroxide, second acrylic monomer, plasticizer, second stabilizer, second auxiliary agent, and filler are mixed and stirred evenly under vacuum conditions at room temperature. After vacuum degassing, the mixture is discharged. The obtained components A and B are poured into A and B tubes respectively using an automatic dispensing machine. After centrifugation to remove bubbles, the tubes are sealed to obtain high-strength acrylic structural adhesive.

[0041] Thirdly, the present invention also provides an application of the high-strength acrylic structural adhesive in structural bonding in fields such as composite materials, laptop assembly, and vehicle interior and exterior trim.

[0042] The sources of raw materials used in the following preparation examples, embodiments, and comparative examples are as follows: Heat-resistant aliphatic hyperbranched polyester with terminal hydroxyl groups, hydroxyl value of 520 mg KOH / g, molecular weight of 1200, purchased from Wuhan Hyperbranched Resin Technology Co., Ltd., brand name H202; p-toluenesulfonic acid purchased from Tianjin Zhonghe Shengtai Chemical Co., Ltd., brand name PTSA; methyl methacrylate purchased from the Exploration Platform; trimethylcyclohexyl acrylate purchased from Shanghai Hesheng Chemical, brand name TMCHA; nitrile rubber purchased from Dalian Liansheng New Material Group Co., Ltd.; N,N-dimethyl-p-toluidine purchased from Zhongshan Dixin Chemical Co., Ltd.; triethylamine purchased from the Exploration Platform; phosphate methacrylate purchased from Changxing Chemical, brand name EM39; p-methoxyphenol purchased from BASF, brand name Irganox MEHQ; tert-butyl hydroperoxide purchased from Arkema, brand name Luperox. TBH; dibutyl phthalate was purchased from Shandong Longhui Chemical Co., Ltd.; calcium carbonate whiskers were purchased from Shanghai Greenia Nanomaterials Co., Ltd.; fumed silica was purchased from Wacker Chemie, Germany, grade H18; polyether acrylate prepolymer was purchased from Changxing Chemical, grade EM226; methacrylic acid was purchased from Exploration Platform.

[0043] Preparation Example 1 A 250mL four-necked flask was equipped with a polytetrafluoroethylene stirrer, a mercury thermometer, a condenser, and a glass stopcock. Under nitrogen protection, 31.64g of methacrylic acid, 10g of heat-resistant aliphatic hyperbranched polyester with terminal hydroxyl groups, and 0.32g of p-toluenesulfonic acid catalyst were added. The oil bath temperature was raised to 140℃ for dehydration reflux reaction for three hours. The reaction was then stopped, cooled to room temperature, dissolved in an appropriate amount of acetone, recrystallized in toluene, filtered, and dried to obtain purified hyperbranched multifunctional acrylate resin.

[0044] Example 1 Preparation of component A: 30 parts of hyperbranched multifunctional acrylate resin, 52.6 parts of primary acrylate monomer (42.6 parts of methyl methacrylate and 10 parts of trimethylcyclohexyl acrylate), 15 parts of nitrile rubber, 1.3 parts of accelerator (1 part of N,N-dimethyl-p-toluidine and 0.3 parts of triethylamine), 0.1 parts of p-methoxyphenol, and 1 part of phosphate methacrylate are mixed and stirred evenly under vacuum conditions. After vacuum degassing, the mixture is discharged. Preparation of component B: 30 parts of tert-butyl hydroperoxide, 20 parts of methyl methacrylate, 20 parts of dibutyl phthalate, 0.1 parts of p-methoxyphenol, 9.9 parts of fumed silica, and 20 parts of calcium carbonate whiskers are mixed and stirred evenly under vacuum at room temperature. After vacuum degassing, the mixture is discharged. The obtained components A and B are poured into A and B tubes respectively using an automatic dispensing machine. After centrifugation to remove bubbles, the tubes are sealed to obtain high-strength acrylic structural adhesive.

[0045] Example 2 Most of the steps in this embodiment are the same as those in Embodiment 1, except that 20 parts of hyperbranched multifunctional acrylate resin and 62.6 parts of the first acrylic monomer (47.6 parts of methyl methacrylate and 15 parts of trimethylcyclohexyl acrylate) are added to component A.

[0046] Example 3 Most of the steps in this embodiment are the same as those in Embodiment 1, except that 25 parts of hyperbranched multifunctional acrylate resin and 57.6 parts of the first acrylic monomer (45.1 parts of methyl methacrylate and 12.5 parts of trimethylcyclohexyl acrylate) are added to component A.

[0047] Example 4 Most of the steps in this embodiment are the same as those in Embodiment 1, except that 35 parts of hyperbranched multifunctional acrylate resin and 47.6 parts of the first acrylic monomer (40.1 parts of methyl methacrylate and 7.5 parts of trimethylcyclohexyl acrylate) are added to component A.

[0048] Example 5 Most of the steps in this embodiment are the same as those in Embodiment 1, except that 40 parts of hyperbranched multifunctional acrylate resin and 42.6 parts of the first acrylic monomer (37.6 parts of methyl methacrylate and 5 parts of trimethylcyclohexyl acrylate) are added to component A.

[0049] Example 6 Most of the steps in this embodiment are the same as those in Embodiment 1, except that 15 parts of hyperbranched multifunctional acrylate resin and 67.6 parts of the first acrylic monomer (52.6 parts of methyl methacrylate and 15 parts of trimethylcyclohexyl acrylate) are added to component A.

[0050] Example 7 Most of the steps in this embodiment are the same as those in Embodiment 1, except that 45 parts of hyperbranched multifunctional acrylate resin and 37.6 parts of the first acrylic monomer (32.6 parts of methyl methacrylate and 5 parts of trimethylcyclohexyl acrylate) are added to component A.

[0051] Example 8 Most of the steps in this embodiment are the same as those in Example 1, except that 52.6 parts of the first acrylic monomer (47.6 parts of methyl methacrylate and 5 parts of trimethylcyclohexyl acrylate) are added to component A.

[0052] Example 9 Most of the steps in this embodiment are the same as those in Example 1, except that 52.6 parts of the first acrylic monomer (37.6 parts of methyl methacrylate and 15 parts of trimethylcyclohexyl acrylate) are added to component A.

[0053] Example 10 Most of the steps in this embodiment are the same as those in Embodiment 1, except that 52.6 parts of the first acrylic monomer (49.6 parts of methyl methacrylate and 3 parts of trimethylcyclohexyl acrylate) are added to component A.

[0054] Example 11 Most of the steps in this embodiment are the same as those in Example 1, except that 52.6 parts of the first acrylic monomer (32.6 parts of methyl methacrylate and 20 parts of trimethylcyclohexyl acrylate) are added to component A.

[0055] Comparative Example 1 Preparation of component A: 25 parts of polyether-type acrylate prepolymer, 5 parts of methacrylic acid, 52.6 parts of primary acrylate monomer (42.6 parts of methyl methacrylate and 10 parts of trimethylcyclohexyl acrylate), 15 parts of nitrile rubber, 1.3 parts of accelerator (1 part of N,N-dimethyl-p-toluidine and 0.3 parts of triethylamine), 0.1 parts of p-methoxyphenol, and 1 part of phosphate methacrylate are mixed and stirred evenly under vacuum conditions. After vacuum degassing, the mixture is discharged. Preparation of component B: 100 parts of peroxide, 100 parts of second acrylic monomer, 100 parts of plasticizer, 100 parts of second stabilizer, 100 parts of second auxiliary agent, and 100 parts of filler are mixed and stirred evenly under vacuum at room temperature. After vacuum degassing, the mixture is discharged. The obtained components A and B are poured into A and B tubes respectively at a volume ratio of 10:1 using an automatic dispensing machine. After centrifugation to remove bubbles, the tubes are sealed to obtain the structural adhesive.

[0056] Comparative Example 2 Most of the steps in this comparative example are the same as those in Comparative Example 1, except that 30 parts of polyether acrylate prepolymer are added to component A, and methacrylic acid is not added.

[0057] Comparative Example 3 Most of the steps in this comparative example are the same as those in Comparative Example 1, except that 30 parts of methacrylic acid are added to component A, and no polyether-type acrylate prepolymer is added.

[0058] The performance of the above embodiments and comparative examples was tested using the following methods: (1) Elongation at break Elongation was evaluated according to GB / T 528-2009. First, the adhesive was poured into a type I mold and allowed to fully cure according to its curing process, forming a uniform dumbbell-shaped sample strip. Then, the width and thickness of the parallel section in the middle of the sample were accurately measured using a thickness gauge and calipers, and the original cross-sectional area was calculated. The original gauge length was marked on the parallel section. Next, the sample was symmetrically clamped in the upper and lower fixtures of the testing machine, and the machine was started to stretch the sample at a constant speed until it completely broke. Finally, the data was recorded, with at least 5 valid samples tested in each group, and the arithmetic mean was taken as the result.

[0059] (2) Pull-out force test Initial pull-out force: Apply adhesive evenly to the L-shaped snap-fit ​​device and aluminum parts, ensuring uniform adhesive layer thickness, and allow to fully cure under specified conditions. Then, place the sample in the push-pull force gauge fixture and pull it out at a constant speed until the bond is completely broken. Record the maximum pull-out force data and observe the failure mode. Test at least 5 valid samples per group and take the arithmetic mean as the result. High-temperature pull-out force test: The L-shaped snap-fit ​​device and aluminum sample after curing and bonding were placed in an 85℃ high-temperature test chamber for 24 hours. After removal, they were immediately pulled out at a constant speed using a push-pull force gauge while maintaining the temperature until the bond was completely destroyed. The maximum pull-out force data was recorded, and the failure mode was observed. At least 5 valid samples were tested in each group, and the arithmetic mean was taken as the result. Pull-out force after damp heat aging: The L-shaped snap-fit ​​device and aluminum sample after curing and bonding were placed in a constant temperature and humidity test chamber at 50℃ and 95%RH for 240 hours. After the test, the sample was removed and allowed to warm up. Then, a push-pull force gauge was used to pull the sample out at a constant speed until the bond was completely broken. The maximum pull-out force data was recorded, and the failure mode was observed. At least 5 valid samples were tested in each group, and the arithmetic mean was taken as the result.

[0060] Pull-out force after high and low temperature cycling aging: The L-shaped snap-fit ​​device and aluminum sample after curing and bonding were placed in an environmental aging chamber at -40℃ / 22h, 23℃ / 2h, 90℃ / 22h, 23℃ / 2h, and 50℃ / 95%RH / 22h for aging tests, and the cycle was repeated 3 times. After the cycle, the sample was removed and pulled out at a constant speed using a push-pull force gauge until the bond was completely destroyed. The maximum pull-out force data was recorded, and the failure mode was observed. At least 5 valid samples were tested in each group, and the arithmetic mean was taken as the result. Pull-out force after high-temperature aging: The L-shaped snap-fit ​​device and aluminum sample after curing and bonding were placed in a high-temperature test chamber at 90℃ for 500 hours. After the test, the sample was removed and allowed to cool to room temperature. Then, a push-pull force gauge was used to pull the sample at a constant speed until the bond was completely broken. The maximum pull-out force data was recorded, and the failure mode was observed. At least 5 valid samples were tested in each group, and the arithmetic mean was taken as the result. Pull-out force after neutral salt spray test: The L-shaped snap-fit ​​device and aluminum sample after curing and bonding were placed in a salt spray test chamber and tested for 480 hours according to GB / T 10125 neutral salt spray test standard. After the test, the sample was removed and stretched at a constant speed using a push-pull force gauge until the bond was completely broken. The maximum pull-out force data was recorded, and the failure mode was observed. At least 5 valid samples were tested in each group, and the arithmetic mean was taken as the result.

[0061] The test results are shown in Table 1.

[0062] Table 1 Based on the data analysis and comparison in Table 1, in Comparative Example 1, similar traditional acrylic structural adhesives typically use polyether-type acrylate prepolymers as the main resin. The dual-end groups participate in curing to form a three-dimensional cross-linked network, and the flexible main chain assists in toughening, thus exhibiting good strength and toughness. However, comparing Examples 1-5 shows that the initial value of the adhesive strength (assessed by pull-out force), the pull-out force at high temperature, and the pull-out force after various aging processes in these examples are significantly better than those in Comparative Example 1. This is because the hyperbranched multifunctional acrylate resin has highly polar hydroxyl and ester bonds, which can more effectively improve the adhesive strength of the structural adhesive than linear polyethers. It also has multiple reactive acrylate groups that can participate in the curing and cross-linking reaction, making... The increased crosslinking density of the structural adhesive results in high bonding strength and salt spray resistance. The hyperbranched core structure provides better freedom of chain segment movement, enhancing its ability to absorb and disperse impact energy (toughening). Simultaneously, the restricted long-range movement of chain segments and the enhanced crosslinking efficiency of terminal multi-groups prevent flow deformation at high temperatures (heat resistance). Compared to traditional linear polyether prepolymers, it can maintain better heat resistance and resistance to damp heat aging while toughening. Finally, the reactive toughening properties of the hyperbranched multifunctional acrylic resin can also solve the problem of poor compatibility caused by excessive addition of traditional toughening agents, providing better toughening effects and further improving the strength of the structural adhesive. In Comparative Example 2, when the polyether-type acrylate prepolymer was used as the main resin to replace the methacrylic acid in Comparative Example 3, the lack of polar groups such as carboxyl and hydroxyl groups resulted in weak adhesive strength. Although the toughness was slightly better due to the higher content of polyether, the overall strength was insufficient, especially the resistance to damp heat and heat. This is because the linear polyether structure has good hydrophilicity, and water vapor can easily penetrate in high humidity and salt spray environments, causing long-range slippage of the molecular chains. Under stress, this manifests as macroscopic displacement of the adhesive layer, resulting in poor resistance to salt spray, damp heat, and heat. In Comparative Example 3, with high... The prepolymer, which uses polar monomer methacrylic acid as the main component and replaces the polyether-type acrylate prepolymer in Comparative Example 2, has good adhesion and high strength due to its high polarity. However, it is significantly less tough, resulting in defects in the molecular cross-linking network structure, excessive rigidity, restricted chain segment movement, and concentrated internal stress. These structural features are amplified during aging processes such as high temperature, accelerating the chemical degradation and physical damage of the adhesive layer, ultimately leading to insufficient heat resistance and a significant decrease in strength. Furthermore, the excessive carboxyl groups significantly increase the hydrophilicity of the cured product, causing a sharp deterioration in its resistance to damp heat.

[0063] Comparing Examples 1-7, it can be seen that the content of hyperbranched multifunctional acrylate resin affects the performance. Example 1 is the optimal formulation, achieving an elongation at break of 15.39%, an initial pull-out force of 254.60 N, a high-temperature pull-out force of 127.10 N, a pull-out force after damp heat aging of 148.90 N, a pull-out force after high and low temperature cycling aging of 232.50 N, a pull-out force after high-temperature aging of 149.80 N, and a pull-out force after neutral salt spray aging of 130.20 N. While increasing the content of hyperbranched multifunctional acrylate resin increases toughness, strength, and weather resistance, when the content exceeds 30 parts, the excessively high proportion of hyperbranched multifunctional acrylate resin and high functional group density lead to overly concentrated exothermic curing reaction. The rapidly accumulated internal stress reduces strength. Furthermore, excessive flexibility also causes the adhesive layer to easily deform, reducing strength. As in Example 7, when the content is increased to 45 parts, the strength significantly decreases. As in Example 6, when the hyperbranched multifunctional acrylate resin was reduced to 15 parts, the toughness was not very high, the elongation at break was only 12.40%, and the strength was also affected to some extent.

[0064] Comparative examples 8-11 show that the addition ratio of methyl methacrylate and trimethylcyclohexyl acrylate in component A will affect the performance of the acrylic structural adhesive after curing to a certain extent. When the proportion of highly polar and rigid trimethylcyclohexyl acrylate is small, although the toughness will increase, the strength will decrease accordingly. When the proportion of trimethylcyclohexyl acrylate is large, the polar and rigid monomers will increase the initial strength, but reduce the toughness.

[0065] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention 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 of the technical features. These modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention, and should all be included within the protection scope of the present invention.

Claims

1. A high-strength acrylate structural adhesive, characterized by, The structural adhesive comprises an A component and a B component; The A component comprises an over-branched multifunctional acrylate resin, a first acrylic monomer, a toughening agent, an accelerator, a first stabilizer; The B component comprises a peroxide, a second acrylic monomer, a plasticizer, a second stabilizer; The over-branched multifunctional acrylate resin is prepared by direct esterification, acyl chloride esterification, ester exchange or addition esterification, etc. of a heat-resistant aliphatic over-branched polyester containing terminal hydroxyl groups and an acrylic reagent, the heat-resistant aliphatic over-branched polyester containing terminal hydroxyl groups has a hydroxyl value of 500-550 mgKOH / g and a molecular weight of 600-3000 g / mol.

2. The high-strength acrylate structural adhesive of claim 1, wherein, The volume ratio of the A component and the B component is 10:

1.

3. The high-strength acrylate structural adhesive of claim 1, wherein, The first acrylic monomer and the second acrylic monomer are at least one selected from the group consisting of acrylic acid, methacrylic acid, methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, butyl acrylate, butyl methacrylate, isobornyl acrylate, isobornyl methacrylate, tetrahydrofurfuryl acrylate, tetrahydrofurfuryl methacrylate, cyclotrimethylopropane formal acrylate, hydroxyethyl acrylate, hydroxyethyl methacrylate, acryloyl morpholine, trimethylcyclohexyl acrylate, p-tert-butylcyclohexyl acrylate, dicyclopentyl acrylate, cyclohexanedimethanol dimethacrylate, ethylene glycol dimethacrylate, diethylene glycol dimethacrylate, butylene glycol dimethacrylate, hexanediol diacrylate, triethylene glycol diacrylate and tripropylene glycol diacrylate; The toughening agent comprises at least one selected from the group consisting of nitrile rubber, polysulfide rubber, polybutadiene rubber, styrene butadiene rubber, styrene, phthalate, ABS resin, polyvinyl acetate, methyl methacrylate-butadiene-styrene terpolymer; The accelerator comprises at least one selected from the group consisting of tertiary amine, thiourea derivative and metal salt; The first stabilizer and the second stabilizer are at least one selected from the group consisting of p-methoxyphenol, EDTA-4Na, hydroquinone, p-phenol, p-benzoquinone and 2,6-di-tert-butyl-4-methylphenol.

4. The high-strength acrylate structural adhesive of claim 1, wherein, The peroxide is at least one selected from the group consisting of dibenzoyl peroxide, dilauryl peroxide, methyl ethyl ketone peroxide, cyclohexanone peroxide, t-amyl hydroperoxide, t-butyl hydroperoxide, cumene peroxide and dicumyl peroxide; The plasticizer comprises at least one selected from the group consisting of dibutyl phthalate, dioctyl phthalate, diethylene glycol phthalate, polyether N330, liquid paraffin and petroleum resin.

5. The high-strength acrylate structural adhesive of claim 1, wherein, The A component of the high-strength acrylate structural adhesive further comprises a first auxiliary agent; the B component further comprises a second auxiliary agent and a filler; The A component comprises, in parts by weight: 20-40 parts of the over-branched multifunctional acrylate resin, 40-65 parts of the first acrylic monomer, 10-20 parts of the toughening agent, 0.1-3 parts of the accelerator, 0.05-3 parts of the first stabilizer, 0.1-3 parts of the first auxiliary agent; The B component comprises: 20-40 parts of peroxide, 10-30 parts of second acrylic monomer, 10-30 parts of plasticizer, 0.05-3 parts of second stabilizer, 5-15 parts of second auxiliary agent, 20-40 parts of filler.

6. The high-strength acrylate structural adhesive of claim 5, wherein, The first acrylic monomer is a combination of methyl methacrylate and trimethylcyclohexyl acrylate; The first acrylic monomer is a combination of methyl methacrylate and trimethylcyclohexyl acrylate; 7. The high-strength acrylate structural adhesive of claim 1, wherein, The preparation method of the hyperbranched multifunctional acrylate resin comprises the following steps: Under the protection of inert gas, the hydroxyl-terminated heat-resistant aliphatic hyperbranched polyester, the acrylic reagent and the catalyst are added into a refluxing device, the temperature is raised to 130-150 DEG C, and refluxing is carried out for 3-6 hours, then the reaction is stopped, and the hyperbranched multifunctional acrylate resin is obtained by purification.

8. The high-strength acrylate structural adhesive of claim 7, wherein, The acrylic reagent comprises at least one of acrylic acid, methacrylic acid, acryloyl chloride, methacryloyl chloride, methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, isocyanate acrylate and isocyanate methacrylate. The molar ratio of the hydroxyl-terminated heat-resistant aliphatic hyperbranched polyester and the acrylic reagent is 1: (5-7).

9. A method for preparing the high-strength acrylate structural adhesive according to any one of claims 1 to 8, characterized in that, The preparation method comprises the following steps: Preparation of component A: the hyperbranched multifunctional acrylate resin, the first acrylic monomer, the toughening agent, the accelerator, the first stabilizer and the first auxiliary agent are mixed and stirred uniformly under vacuum condition, and then the vacuum degassing is carried out, and the material is discharged; Preparation of component B: the peroxide, the second acrylic monomer, the plasticizer, the second stabilizer, the second auxiliary agent and the filler are mixed and stirred uniformly under room temperature vacuum condition, and then the vacuum degassing is carried out, and the material is discharged; The obtained A component and B component are respectively filled into A and B glue pipes by using an automatic glue filling machine, centrifugal degassing is carried out, and the high-strength acrylate structural glue is obtained.

10. The high-strength acrylate structural glue prepared by the preparation method of any one of claims 1-8 or any one of claims 9 is applied in structural bonding in the fields of composite materials, notebook computer assembly, vehicle body interior and exterior decoration, etc.

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