High mechanical strength aramid modified ms resin and adhesive therefor

Abstract

The application belongs to the technical field of adhesive preparation, and particularly relates to a high-mechanical-strength aramid fiber modified MS resin and an adhesive thereof. The modified MS resin is obtained by shearing and blending raw materials of grafted aramid short-cut fibers, acrylate core-shell particles and silane-terminated polyether resin, and the high-mechanical-strength MS adhesive is prepared by taking the resin as a matrix, cooperating with inorganic fillers, a step-by-step water removal process and an interface adhesion promoter, so that the defects of insufficient cohesive strength and low tear strength of the existing MS resin adhesive are overcome.

Description

Technical Field

[0001] This invention belongs to the field of adhesive preparation technology, specifically relating to a high mechanical strength aramid-modified MS resin and its adhesive. Background Technology

[0002] Silane-terminated polyether resins (MS resins), due to their flexible polyether main chain structure and crosslinkable siloxane groups at the ends, possess excellent weather resistance, environmental friendliness, and good coatability. They also exhibit excellent adhesion to various substrates, making them widely used in building sealing, automotive interior decoration, and electronic component bonding. However, with the development of modern industry towards high integration and high load-bearing capacity, existing MS resin adhesives have the following drawbacks: The weak intermolecular forces between current MS resin molecular chain segments result in low cohesive strength after curing. This low cohesive strength leads to a significant decrease in overall mechanical strength, making it difficult to meet the requirements of modern industry. To improve the mechanical strength of MS resins, modification with large amounts of nanoscale inorganic fillers is commonly used. However, in actual production, excessive amounts of inorganic fillers can cause a sharp increase in system viscosity, leading to processing difficulties, severely damaging the elongation at break of the elastomer, and easily causing brittle fracture. Recently, there has been an increasing number of studies attempting to use fiber materials for reinforcement. However, due to the extremely poor interfacial compatibility between these fiber materials and the organic MS resin matrix, they are prone to fiber pull-out and interfacial peeling when subjected to external forces, resulting in poor modification effects.

[0003] Aramid fibers possess ultra-high strength, high modulus, and high temperature resistance, making them ideal reinforcing materials. However, the surface of aramid fibers is highly crystalline and lacks active functional groups, exhibiting chemical inertness. How to achieve efficient activation and modification of the aramid fiber surface under mild conditions without compromising its intrinsic strength, allowing it to integrate and synergistically reinforce the MS resin matrix, is a pressing problem in the field of polymer adhesives. Summary of the Invention

[0004] To address at least one of the above problems, this invention provides a method for preparing a high-mechanical-strength aramid-modified MS resin, comprising the following steps: S1. Aramid chopped fibers are activated by plasma under a mixed atmosphere and then placed in an alcohol solution containing silane coupling agent. After heating and reaction, they are washed and dried to obtain grafted aramid chopped fibers. S2. Using raw materials including grafted aramid short-cut fibers, acrylate core-shell rubber particles, and silane-terminated polyether resin, aramid-modified MS resin is obtained by heating and shearing blending under an inert atmosphere.

[0005] Furthermore, in step S1, the plasma activation process conditions are: discharge power of 200-300W, bombardment time of 10-15min; and the mixed atmosphere is a mixture of oxygen and argon at a volume ratio of 1:3-5.

[0006] Further, in step S1, the method for preparing the alcohol solution containing the silane coupling agent is as follows: Anhydrous ethanol and deionized water are mixed in a mass ratio of 10:85-95:0.6-1 (water, anhydrous ethanol, and silane coupling agent). The silane coupling agent is then added to the mixture at a rotation speed of 200-300 r / min. After thorough mixing, the pH of the system is adjusted to 5.0, and the mixture is hydrolyzed at room temperature for 25-45 min to obtain the alcohol solution containing the silane coupling agent.

[0007] Further, in step S2, the mass ratio of silane-terminated polyether resin, grafted aramid chopped fiber, and acrylate core-shell rubber particles is 100:4-8:3-6.

[0008] A high mechanical strength aramid-modified MS resin is prepared by the preparation method of a high mechanical strength aramid-modified MS resin as described in any of the above technical solutions.

[0009] Further, by weight, it comprises 35-50 parts of the aramid-modified MS resin as described in claim 5, 6-8 parts of plasticizer, 38-43 parts of inorganic filler, 1.8-2.2 parts of dehydrating agent, 2.5-3.5 parts of rheology and thixotropic agent, 0.6-0.8 parts of interfacial thickening accelerator, 0.6-0.8 parts of anti-aging agent, and 0.25-0.3 parts of catalyst.

[0010] Furthermore, the inorganic filler is composed of heavy calcium carbonate and light calcium carbonate in a mass ratio of 1.3-1.5:1.

[0011] Furthermore, the interfacial adhesion promoter is a compound of at least two of the following: monoaminosilane coupling agents, diaminosilane coupling agents, and epoxysilane coupling agents.

[0012] A method for preparing a high mechanical strength aramid-modified MS resin adhesive includes the following steps: Raw materials comprising aramid-modified MS resin, plasticizer, and a first-part dehydrating agent are added to a vacuum mixer and stirred uniformly under an inert atmosphere. Then, raw materials comprising inorganic fillers, rheological thixotropic agents, and anti-aging additives are added. The temperature is controlled at 42-48℃, and the vacuum degree is -0.1MPa to -0.095MPa. After high-speed shear mixing for 40-60 minutes, the temperature is lowered to 30-33℃. Subsequently, raw materials comprising a second-part dehydrating agent, an interfacial thickening accelerator, and a catalyst are added. The mixture is then reacted under an inert atmosphere for 10-15 minutes. The temperature is then controlled at 25-30℃, and the rotation speed is reduced to 100-200 r / min. After degassing under vacuum for 10-15 minutes, the adhesive is obtained.

[0013] Furthermore, the first part of the dehydrating agent accounts for 60%-70% of the total mass of the dehydrating agent.

[0014] The present invention has the following beneficial effects: This invention uses low-temperature plasma in a mixed atmosphere of oxygen and argon to bombard the surface of aramid fibers, forming micro-nano-scale pits and grooves on the fiber surface without damaging the fiber strength, thus significantly increasing the specific surface area. At the same time, highly active oxygen free radicals bombard the fiber molecular chains, causing partial opening of amide bonds and rapidly generating high-density active functional groups such as hydroxyl and carboxyl groups on the fiber surface. These functional groups then undergo dehydration condensation reactions with the hydrolysis products of silane coupling agents, bonding siloxane segments to the surface of the aramid fibers and enhancing compatibility with the matrix resin. Furthermore, this invention introduces grafted and modified aramid chopped fibers as a rigid reinforcing phase into MS resin, and synergizes with acrylate core-shell rubber particles as a flexible toughening phase, successfully forming a composite network that combines rigidity and flexibility within the resin matrix. When the cured elastomer is subjected to external force, the uniformly dispersed acrylate core-shell rubber particles in the system, acting as flexible soft segments, preferentially undergo shear band induction and creasing, thereby preventing crack propagation and absorbing a large amount of impact energy. Simultaneously, the modified aramid chopped fibers, acting as rigid segments, allow the applied stress to be transferred from the resin matrix to the high-modulus aramid fiber skeleton, preventing tearing of the elastomer. During the adhesive preparation process, a stepwise addition of dehydrating agents is employed, effectively eliminating the risk of dead glue or gelation caused by trace amounts of moisture catalyzing premature hydrolysis and crosslinking of the terminal methoxy groups in the MS resin during the high-temperature production stage. Detailed Implementation

[0015] The technical solutions in the embodiments of this application will be clearly and completely described below with reference to the embodiments of this application. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this application.

[0016] Silane-terminated polyether resins (MS resins), due to their flexible polyether main chain structure and crosslinkable siloxane groups at the ends, combine the advantages of polyurethane and silicone rubber, exhibiting excellent weather resistance, environmental friendliness, coatability, and adhesion to various substrates. They are widely used in building sealing, automotive interiors, and electronic component bonding. However, traditional MS resins suffer from weak inter-segment forces, resulting in low cohesive strength and reduced mechanical strength after curing, making it difficult to meet the requirements of high load-bearing capacity, long lifespan, and high-temperature resistance. Therefore, this invention provides a method for preparing a high-mechanical-strength aramid-modified MS resin, comprising the following steps: S1. Aramid chopped fibers are activated by plasma under a mixed atmosphere and then placed in an alcohol solution containing silane coupling agent. After heating and reaction, they are washed and dried to obtain grafted aramid chopped fibers. S2. Using raw materials including grafted aramid short-cut fibers, acrylate core-shell rubber particles, and silane-terminated polyether resin, aramid-modified MS resin is obtained by heating and shearing blending under an inert atmosphere.

[0017] Specifically, step S1 involves placing aramid chopped fibers in a high-frequency low-temperature plasma reactor and performing surface activation bombardment in a mixed atmosphere of oxygen and argon. After bombardment, the activated fibers are placed in a pre-prepared alcohol solution containing silane coupling agent, the temperature is raised to 55-65℃, and the reaction is carried out with constant temperature stirring for 3-5 hours. After the reaction, the supernatant is removed by centrifugation, and the fibers are washed 3-5 times with anhydrous ethanol and then dried in a vacuum drying oven at 75-85℃ for 6-8 hours to obtain grafted aramid chopped fibers.

[0018] In this step, the average length of the aramid chopped fibers is 1-3 mm, and the aspect ratio is 80-150. The plasma activation process conditions are: discharge power of 200-300 W, bombardment time of 10-15 min; and the volume ratio of oxygen to argon in the mixed atmosphere is 1:3-5. The preparation method of the alcohol solution containing silane coupling agent is as follows: Anhydrous ethanol and deionized water are mixed at a mass ratio of water, anhydrous ethanol, and silane coupling agent of 10:85-95:0.6-1. The silane coupling agent is then slowly added at a rotation speed of 200-300 r / min. After addition, the pH of the system is adjusted to 5.0 using a 10% acetic acid solution, and hydrolyzed at room temperature for 25-45 min to obtain the alcohol solution containing silane coupling agent. The silane coupling agent is one or more of KH-550, KH-560, and KH-570.

[0019] In this process, due to the extremely high symmetry and dense crystalline regions of aramid fibers, their surface lacks chemical activity, making direct graft modification of aramid fibers quite difficult. Therefore, this invention first employs plasma to treat the fiber surface. In an oxygen and argon plasma environment, high-energy Ar+ ions intensely bombard the fiber surface, forming micro- and nano-scale pits and grooves. Simultaneously, highly reactive oxygen free radicals bombard the aramid molecular chains, causing partial opening of their amide bonds and rapidly generating a high density of active functional groups such as hydroxyl and carboxyl groups on the fiber surface, providing active sites for subsequent grafting. A silane coupling agent hydrolyzes in a water-alcohol system at pH 5.0 to generate a silanol intermediate. When activated aramid fibers are added to this system, the active groups on the fiber surface undergo dehydration condensation with the silanol intermediate, bonding siloxane segments to the aramid fiber surface.

[0020] Specifically, step S2 involves weighing the following materials according to a mass ratio of silane-terminated polyether resin, grafted aramid chopped fiber, and acrylate core-shell rubber particles of 100:4-8:3-6. These materials are then added to a reaction vessel, protected with nitrogen gas, and the temperature is raised to 70-80°C. High-speed shearing is then initiated, and the reaction is carried out at a rotation speed of 1000-2000 r / min for 2-3 hours. Heating is then stopped, and the temperature is lowered to below 40°C. Stirring is then stopped, and the material is discharged to obtain aramid-modified MS resin.

[0021] In this step, the silane-terminated polyether resin is dimethylmethoxysilane-terminated polyoxypropylene ether: MS resin, Zhongyuan Chemical SAX-400, viscosity 7000 mPa·s; acrylate core-shell rubber particles (CSR) are pure solid powders, which are nanoscale elastomers with polybutyl acrylate as the core and polymethyl methacrylate as the shell: Zhongyuan Chemical, Kane Ace FM-40, particle size 100-150 nm; high-purity nitrogen: purity ≥99.999%.

[0022] During this process, under the combined action of heating and mechanical shearing, the siloxane segments on the surface of the grafted aramid chopped fibers exhibit good compatibility with the polyether backbone and terminal methoxysilanes of the MS resin, and can form molecular chain entanglement with the PMMA shell of the acrylate core-shell rubber particles. When the modified MS resin system is subjected to external force, the acrylate core-shell rubber particles dispersed in the system, as soft segments, undergo shear band induction and crimping, absorbing a large amount of energy; while the aramid fibers, as rigid segments, have high interfacial shear strength with the matrix, allowing stress to be transferred from the matrix to the high-modulus aramid fiber skeleton, preventing the elastomer from tearing.

[0023] One method for preparing a high-mechanical-strength aramid-modified MS resin adhesive includes the following steps: Aramid-modified MS resin, plasticizer, and a first-part dehydrating agent are added to a vacuum mixer. Nitrogen gas is introduced, and the mixture is stirred evenly at 100-200 r / min. Inorganic fillers, rheological thixotropic agents, and anti-aging additives are then added. The temperature is raised to 42-48℃, and a vacuum is drawn to a vacuum degree of -0.1 MPa to -0.095 MPa. High-speed shearing is then initiated at 1500-2500 r / min. After mixing at a speed of n for 40-60 minutes, nitrogen gas is introduced to break the vacuum and the temperature is lowered to 30-33℃. Then, the dehydrating agent, interfacial thickening agent and catalyst from the second part are added. Under nitrogen protection, the mixture is mixed and reacted at a speed of 300-500 r / min for 10-15 minutes, and the temperature is controlled at 25-30℃. The speed is reduced to 100-200 r / min, and the vacuum is turned on to -0.1MPa to -0.095MPa. After degassing for 10-15 minutes, the adhesive is discharged.

[0024] In this step, by weight, the following components are used: 35-50 parts of aramid-modified MS resin, 6-8 parts of plasticizer, 38-43 parts of inorganic filler, 1.8-2.2 parts of dehydrating agent, 2.5-3.5 parts of rheology and thixotropic agent, 0.6-0.8 parts of interfacial thickening accelerator, 0.6-0.8 parts of anti-aging agent, and 0.25-0.3 parts of catalyst. The plasticizer is polypropylene glycol PPG-3000 (industrial grade, moisture ≤0.02%); the inorganic filler is a mixture of heavy calcium carbonate (GCC, 1000 mesh, dried at 105℃ for 4 hours) and light calcium carbonate (PCC, 50nm) in a mass ratio of 1.3-1.5:1; the dehydrating agent is vinyltrimethoxysilane (purity ≥98%); the rheology and thixotropic agent is fumed silica (HB151, Evonik Industries); and the interfacial thickening accelerator... The additive is a compound of at least two of the following: monoaminosilane coupling agents, diaminosilane coupling agents, and epoxysilane coupling agents, preferably a compound of coupling agent KH-792 and coupling agent KH-560 in a 1:1 mass ratio; the anti-aging additive is a compound of antioxidant and light stabilizer in a 1:1 mass ratio, preferably a compound of antioxidant 1076 and light stabilizer UV-292 in a 1:1 mass ratio; the catalyst is bismuth neodecanoate (bismuth content 20%). The first part of the dehydrating agent accounts for 60%-70% of the total mass of the dehydrating agent, and the remaining 30%-40% is the second part of the dehydrating agent.

[0025] In this process, even after pre-drying, the inorganic filler still contains bound and adsorbed water on its surface. When the catalyst, interfacial thickening agent, filler, and resin are mixed in the same system, trace amounts of water will catalyze the premature hydrolysis and crosslinking of the methoxy groups at the ends of the MS resin at high temperatures. Therefore, in the first stage, a portion of the dehydrating agent vinyltrimethoxysilane is added. Vinyltrimethoxysilane's hydrolytic activity is much higher than that of the MS resin end groups, and it preferentially reacts with and removes water molecules from the filler surface, thus thoroughly drying the matrix. When the temperature drops to 30-33℃, the second portion of the dehydrating agent, interfacial thickening agent, and catalyst are added. The added mono / diaminosilane coupling agents and epoxysilane coupling agents can form an interpenetrating network structure, exhibiting strong chemical bonding to various substrates while ensuring stability in industrial production.

[0026] Example 1 A method for preparing a high mechanical strength aramid-modified MS resin includes the following steps: S1. 100g of aramid chopped fibers were placed in a high-frequency low-temperature plasma reactor and surface-activated under a mixed atmosphere of oxygen and argon (volume ratio of oxygen to argon was 1:4). The discharge power was set to 250W and the bombardment time was 12min. After the bombardment, the activated fibers were placed in a pre-prepared alcohol solution containing silane coupling agent. The temperature was raised to 60℃ and the reaction was stirred at a constant temperature for 4h. After the reaction, the supernatant was removed by centrifugation. The precipitate was washed four times with anhydrous ethanol and then dried in a vacuum drying oven at 80℃ for 7h to obtain grafted aramid chopped fibers. The preparation method of the alcohol solution containing silane coupling agent was as follows: 200g of anhydrous ethanol and 22.2g of deionized water were mixed and 1.8g of KH-550 was slowly added at a speed of 250r / min. After the addition was completed, the pH of the system was adjusted to 5.0 with 10% acetic acid solution and hydrolyzed at room temperature for 35min to obtain the alcohol solution containing silane coupling agent. S2. Add 500g MS resin, 30g grafted aramid chopped fiber and 22.5g acrylate core-shell rubber particles to the reactor, then introduce nitrogen for protection, raise the temperature to 75℃, turn on high-speed shearing, and shear the reaction at 1500r / min for 2.5h. Then turn off the heating, cool down to below 40℃, stop stirring and discharge the material to obtain aramid modified MS resin.

[0027] A method for preparing a high mechanical strength aramid-modified MS resin adhesive, comprising the following steps: In a vacuum mixer, 42 parts by weight of aramid-modified MS resin, 7 parts by weight of polypropylene glycol PPG-3000, and 1.3 parts by weight of dehydrating agent vinyltrimethoxysilane (65% of the total mass of the dehydrating agent) are added. Nitrogen gas is introduced, and the mixture is stirred evenly at 150 r / min. Then, 40 parts by weight of inorganic filler (composed of heavy calcium carbonate and light calcium carbonate in a mass ratio of 1.4:1), 3 parts by weight of fumed silica, and 0.7 parts by weight of anti-aging agent (composed of antioxidant 1076 and light stabilizer UV-292 in a mass ratio of 1:1) are added. The temperature is raised to 45°C, and a vacuum is drawn to a vacuum degree of -0. At a pressure of 0.098 MPa, high-speed shearing was initiated, and the mixture was stirred at 2000 r / min for 50 min. Nitrogen gas was then introduced to break the vacuum, and the temperature was lowered to 31°C. Subsequently, 0.7 parts of the second part dehydrating agent vinyltrimethoxysilane (accounting for 35% of the total mass of the dehydrating agent), 0.7 parts of the interface thickening accelerator (coupling agent KH-792 and coupling agent KH-560 compounded in a mass ratio of 1:1) and 0.28 parts of bismuth neodecanoate were added. The mixture was then resealed and stirred at 400 r / min for 12 min under nitrogen protection. The temperature was then controlled at 27°C, the stirring speed was reduced to 150 r / min, and the vacuum was turned on to -0.098 MPa. After degassing for 12 min, the adhesive was discharged.

[0028] Example 2 This embodiment differs from Embodiment 1 in the following ways: In step S1, the mixed atmosphere is composed of oxygen and argon in a volume ratio of 1:3. During plasma activation, the discharge power is set to 200W and the bombardment time is 15min. The activated fiber is placed in a pre-prepared alcohol solution containing silane coupling agent, the temperature is raised to 55℃, and the reaction is carried out with constant temperature stirring for 5h. After the reaction, the fiber is centrifuged, washed, and then dried in a vacuum drying oven at 75℃ for 8h to obtain grafted aramid short-cut fiber. The preparation method of the alcohol solution containing silane coupling agent is as follows: 170g of anhydrous ethanol and 20g of deionized water are mixed and 1.2g of KH-550 is slowly added at a speed of 200r / min. After the addition is completed, the pH of the system is adjusted to 5.0 with 10% acetic acid solution, and hydrolyzed at room temperature for 25min to obtain the alcohol solution containing silane coupling agent.

[0029] In step S2, 500g of MS resin, 20g of grafted aramid chopped fiber and 15g of acrylate core-shell rubber particles are added to the reactor. Then, nitrogen gas is introduced for protection, the temperature is raised to 70°C, and the reaction is sheared at 1000r / min for 3 hours. After that, the heating is turned off, the material is cooled and discharged to obtain aramid-modified MS resin.

[0030] A method for preparing a high mechanical strength aramid-modified MS resin adhesive, comprising the following steps: In a vacuum mixer, 35 parts by weight of aramid-modified MS resin, 6 parts by weight of polypropylene glycol PPG-3000, and 1.08 parts by weight of dehydrating agent vinyltrimethoxysilane (accounting for 60% of the total mass of the dehydrating agent) are added. Nitrogen gas is introduced, and the mixture is stirred evenly at 100 r / min. Then, 38 parts by weight of inorganic filler (composed of heavy calcium carbonate and light calcium carbonate in a mass ratio of 1.3:1), 2.5 parts by weight of fumed silica, and 0.6 parts by weight of anti-aging agent (composed of antioxidant 1076 and light stabilizer UV-292 in a mass ratio of 1:1) are added. The temperature is raised to 42°C, and a vacuum is drawn to a vacuum degree of - At 0.095 MPa, high-speed shearing was initiated, and the mixture was stirred at 1500 r / min for 60 min. Nitrogen gas was then introduced to break the vacuum, and the temperature was lowered to 30°C. Subsequently, 0.72 parts of the second part dehydrating agent vinyltrimethoxysilane (accounting for 40% of the total mass of the dehydrating agent), 0.6 parts of the interface thickening accelerator (coupling agent KH-792 and coupling agent KH-560 compounded in a mass ratio of 1:1) and 0.25 parts of bismuth neodecanoate were added. The mixture was then resealed and stirred at 300 r / min for 15 min under nitrogen protection. The temperature was then controlled at 25°C, the speed was reduced to 100 r / min, and the vacuum was turned on to -0.095 MPa. After degassing for 15 min, the adhesive was discharged.

[0031] Example 3 This embodiment differs from Embodiment 1 in the following ways: In step S1, the mixed atmosphere is composed of oxygen and argon mixed at a volume ratio of 1:5. During plasma activation, the discharge power is set to 300W and the bombardment time is 10min. The activated fiber is placed in a pre-prepared alcohol solution containing silane coupling agent, the temperature is raised to 65℃, and the reaction is stirred at a constant temperature for 3h. After the reaction, the fiber is centrifuged, washed, and then dried in a vacuum drying oven at 85℃ for 6h to obtain grafted aramid short-cut fiber. The preparation method of the alcohol solution containing silane coupling agent is as follows: 190g of anhydrous ethanol and 20g of deionized water are mixed and 2g of KH-550 is slowly added at a speed of 300r / min. After the addition is completed, the pH of the system is adjusted to 5.0 using a 10% acetic acid solution, and hydrolyzed at room temperature for 45min to obtain the alcohol solution containing silane coupling agent.

[0032] In step S2, 500g of MS resin, 40g of grafted aramid chopped fiber and 30g of acrylate core-shell rubber particles are added to the reactor. Then, nitrogen gas is introduced for protection, the temperature is raised to 80°C, and the reaction is sheared at 2000r / min for 2 hours. After that, the heating is turned off, the material is cooled and discharged to obtain aramid-modified MS resin.

[0033] A method for preparing a high mechanical strength aramid-modified MS resin adhesive, comprising the following steps: In a vacuum mixer, 50 parts by weight of aramid-modified MS resin, 8 parts by weight of polypropylene glycol PPG-3000, and 1.54 parts by weight of dehydrating agent vinyltrimethoxysilane (70% of the total mass of the dehydrating agent) are added. Nitrogen gas is introduced, and the mixture is stirred evenly at 200 r / min. Then, 43 parts by weight of inorganic filler (composed of heavy calcium carbonate and light calcium carbonate in a mass ratio of 1.5:1), 3.5 parts by weight of fumed silica, and 0.8 parts by weight of anti-aging additive (composed of antioxidant 1076 and light stabilizer UV-292 in a mass ratio of 1:1) are added. The temperature is raised to 48°C, and a vacuum is drawn. The pressure was -0.1 MPa. High-speed shearing was started, and the mixture was stirred at 2500 r / min for 40 min. Nitrogen gas was introduced to break the vacuum and the temperature was lowered to 33°C. Then, 0.66 parts of the second part dehydrating agent vinyltrimethoxysilane (accounting for 30% of the total mass of the dehydrating agent), 0.8 parts of the interface thickening accelerator (coupling agent KH-792 and coupling agent KH-560 compounded in a mass ratio of 1:1) and 0.3 parts of bismuth neodecanoate were added. The mixture was resealed and stirred at 500 r / min for 10 min under nitrogen protection. The temperature was then controlled at 30°C, the speed was reduced to 200 r / min, the vacuum was turned on to -0.1 MPa, and the mixture was degassed for 10 min. The adhesive was then discharged.

[0034] Example 4 This embodiment differs from Embodiment 1 in the following ways: In step S1, during plasma activation, the discharge power is set to 240W and the bombardment time is 13min. The activated fiber is placed in a pre-prepared alcohol solution containing silane coupling agent, the temperature is raised to 58℃, and the reaction is carried out under constant temperature stirring for 4.5h. After the reaction, the fiber is centrifuged, washed, and dried to obtain grafted aramid short-cut fiber. The preparation method of the alcohol solution containing silane coupling agent is as follows: 184g of anhydrous ethanol and 20g of deionized water are mixed and 1.4g of compound coupling agent (KH-550 and KH-560 are compounded in a mass ratio of 1:1) is slowly added at a speed of 240r / min. After the addition is completed, the pH of the system is adjusted to 5.0 with 10% acetic acid solution and hydrolyzed at room temperature for 30min to obtain the alcohol solution containing silane coupling agent.

[0035] In step S2, 500g of MS resin, 25g of grafted aramid chopped fiber and 20g of acrylate core-shell rubber particles are added to the reactor. Under nitrogen atmosphere, the reaction is sheared at a speed of 1200r / min for 2h, then the heating is turned off, the material is cooled and discharged to obtain aramid modified MS resin.

[0036] A method for preparing a high mechanical strength aramid-modified MS resin adhesive, comprising the following steps: In a vacuum mixer, 40 parts by weight of aramid-modified MS resin, 6.5 parts by weight of polypropylene glycol PPG-3000, and 1.2 parts by weight of dehydrating agent vinyltrimethoxysilane (63% of the total mass of the dehydrating agent) are added. Nitrogen gas is introduced, and the mixture is stirred evenly at 120 r / min. Then, 41 parts by weight of inorganic filler (composed of heavy calcium carbonate and light calcium carbonate in a mass ratio of 1.35:1), 2.8 parts by weight of fumed silica, and 0.75 parts by weight of anti-aging agent (composed of antioxidant 1076 and light stabilizer UV-292 in a mass ratio of 1:1) are added. The temperature is raised to 44°C, and a vacuum is drawn to a vacuum level. The pressure was set to -0.096 MPa. High-speed shearing was initiated, and the mixture was stirred at 1800 r / min for 55 min. Nitrogen gas was then introduced to break the vacuum, and the temperature was lowered to 32°C. Subsequently, 0.7 parts of the second part dehydrating agent, vinyltrimethoxysilane (37% of the total mass of the dehydrating agent), 0.75 parts of the interfacial tackifier (coupling agent KH-792 and coupling agent KH-560 compounded in a 1:1 mass ratio), and 0.26 parts of bismuth neodecanoate were added. The mixture was then resealed and stirred at 350 r / min for 13 min under nitrogen protection. The temperature was then controlled at 26°C, the speed was reduced to 120 r / min, and the vacuum was set to -0.096 MPa. Degassing was performed for 13 min, and the adhesive was discharged.

[0037] Example 5 This embodiment differs from Embodiment 1 in the following ways: In step S1, during plasma activation, the discharge power is set to 280W and the bombardment time is 11min. The activated fiber is placed in a pre-prepared alcohol solution containing silane coupling agent, the temperature is raised to 62℃, and the reaction is carried out under constant temperature stirring for 3.5h. After the reaction, the fiber is centrifuged, washed, and dried to obtain grafted aramid short-cut fiber. The preparation method of the alcohol solution containing silane coupling agent is as follows: 176g of anhydrous ethanol and 20g of deionized water are mixed and 1.8g of compound coupling agent (KH-550 and KH-570 are compounded in a mass ratio of 1:1) is slowly added at a speed of 280r / min. After the addition is completed, the pH of the system is adjusted to 5.0 with 10% acetic acid solution and hydrolyzed at room temperature for 40min to obtain the alcohol solution containing silane coupling agent.

[0038] In step S2, 500g of MS resin, 35g of grafted aramid chopped fiber and 25g of acrylate core-shell rubber particles were added to the reactor. Under a nitrogen atmosphere, the reaction was sheared at a speed of 1800r / min for 2.2h. Then the heating was turned off, the material was cooled and discharged to obtain aramid-modified MS resin.

[0039] A method for preparing a high mechanical strength aramid-modified MS resin adhesive, comprising the following steps: In a vacuum mixer, 45 parts by weight of aramid-modified MS resin, 7.5 parts by weight of polypropylene glycol PPG-3000, and 1.4 parts by weight of dehydrating agent vinyltrimethoxysilane (accounting for 68% of the total mass of the dehydrating agent) are added. Nitrogen gas is introduced, and the mixture is stirred evenly at 180 r / min. Then, 42 parts by weight of inorganic filler (composed of heavy calcium carbonate and light calcium carbonate in a mass ratio of 1.45:1), 3.2 parts by weight of fumed silica, and 0.65 parts by weight of anti-aging additive (composed of antioxidant 1076 and light stabilizer UV-292 in a mass ratio of 1:1) are added. The temperature is raised to 46°C, and a vacuum is drawn to a vacuum degree of [missing information]. At -0.098 MPa, high-speed shearing was initiated, and the mixture was stirred at 2200 r / min for 45 min. Nitrogen gas was then introduced to break the vacuum, and the temperature was lowered to 32°C. Subsequently, 0.66 parts of the second part dehydrating agent vinyltrimethoxysilane (accounting for 32% of the total mass of the dehydrating agent), 0.65 parts of the interface thickening accelerator (coupling agent KH-792 and coupling agent KH-560 compounded in a mass ratio of 1:1) and 0.26 parts of bismuth neodecanoate were added. The mixture was then resealed and stirred at 450 r / min for 11 min under nitrogen protection. The temperature was then controlled at 28°C, the speed was reduced to 150 r / min, and the vacuum was turned on to -0.098 MPa. After degassing for 11 min, the adhesive was discharged.

[0040] Comparative Example 1 Compared with Example 1, in this comparative example, the aramid chopped fibers were not plasma activated during the preparation process in step S1. Instead, the untreated aramid chopped fibers were directly immersed in the prepared alcohol solution containing silane coupling agent for heating reaction. All other steps were the same as in Example 1.

[0041] Comparative Example 2 Compared with Example 1, in the preparation process of step S1, the aramid short-cut fibers were directly washed and dried after plasma surface activation, without being put into the alcohol solution containing silane coupling agent for reaction. The rest were the same as in Example 1.

[0042] Comparative Example 3 Compared with Example 1, this comparative example does not add grafted aramid short-cut fibers in the preparation process of step S2. That is, step S2 contains 530g MS resin and 22.5g acrylate core-shell rubber particles, and the rest are the same as in Example 1.

[0043] Comparative Example 4 Compared with Example 1, this comparative example does not add acrylate core-shell rubber particles in step S2. That is, step S2 contains 522.5g of MS resin and 30g of grafted aramid chopped fiber. The rest are the same as in Example 1.

[0044] Comparative Example 5 Compared with Example 1, in this comparative example, the dehydrating agent is not added in stages during the adhesive preparation process. Instead, it is added all at once during the initial mixing. The preparation process of a high mechanical strength aramid-modified MS resin adhesive is as follows: 42 parts by weight of aramid-modified MS resin, 7 parts of polypropylene glycol PPG-3000, and 2 parts of the dehydrating agent vinyltrimethoxysilane are added to a vacuum mixer. Nitrogen gas is introduced, and the mixture is stirred evenly at 150 r / min. Then, 40 parts of inorganic filler (composed of heavy calcium carbonate and light calcium carbonate in a mass ratio of 1.4:1), 3 parts of fumed silica, and 0.7 parts of anti-aging additives (antioxidant 1076 and light stabilizer U) are added. V-292 (mixed in a 1:1 mass ratio) was heated to 45°C, and a vacuum was drawn to -0.098 MPa. High-speed shearing was started, and the mixture was stirred at 2000 r / min for 50 min. Nitrogen gas was then introduced to break the vacuum, and the temperature was lowered to 31°C. Subsequently, 0.7 parts of interfacial thickening accelerator (coupling agent KH-792 and coupling agent KH-560 mixed in a 1:1 mass ratio) and 0.28 parts of bismuth neodecanoate were added. The mixture was resealed and stirred at 400 r / min for 12 min under nitrogen protection. The temperature was then controlled at 27°C, the stirring speed was reduced to 150 r / min, and a vacuum was drawn to -0.098 MPa. The mixture was degassed for 12 min, and the adhesive was discharged.

[0045] The rest are the same as in Example 1.

[0046] Comparative Example 6 Compared with Example 1, in the preparation process of this comparative example, the dehydrating agent is not added in steps, but added all at once after vacuum high-speed shearing and cooling. This is a method for preparing a high mechanical strength aramid-modified MS resin adhesive. The preparation process is as follows: 42 parts by weight of aramid-modified MS resin and 7 parts by weight of polypropylene glycol PPG-3000 are added to a vacuum mixer. Nitrogen gas is introduced, and the mixture is stirred evenly at 150 r / min. Then, 40 parts by weight of inorganic filler (composed of heavy calcium carbonate and light calcium carbonate in a mass ratio of 1.4:1), 3 parts by weight of fumed silica, and 0.7 parts by weight of anti-aging additive (antioxidant 1076 and light stabilizer UV-292 in a mass ratio of 1:1) are added. (Formulated), raise the temperature to 45℃, evacuate to a vacuum degree of -0.098MPa, turn on high-speed shear and mix at a speed of 2000r / min for 50min, then introduce nitrogen to break the vacuum, lower the temperature to 31℃, then add 2 parts of dehydrating agent vinyltrimethoxysilane, 0.7 parts of interfacial tackifier (coupling agent KH-792 and coupling agent KH-560 compounded in a mass ratio of 1:1) and 0.28 parts of bismuth neodecanoate, reseal, and mix and react at a speed of 400r / min for 12min under nitrogen protection, then control the temperature to 27℃, reduce the speed to 150r / min, turn on the vacuum to -0.098MPa, degas for 12min, and discharge the material to obtain the adhesive.

[0047] The rest are the same as in Example 1.

[0048] Related tests Tensile strength and elongation at break tests: Tests were conducted according to the relevant provisions of GB / T 528-2009. Specifically, the adhesives prepared in each example and comparative example were placed in a polytetrafluoroethylene mold and smoothed with a scraper to form a uniform film with a thickness of 2.0 mm. The films were cured for 14 days at room temperature (23±2℃) and relative humidity (50±10%). After complete curing, the films were punched into long dumbbell-shaped specimens. These specimens were fixed on the upper and lower clamps of a universal electronic materials testing machine, and the tensile speed was set to 500 mm / min. The testing machine was started until the specimens were completely broken, and the relevant data were recorded, as shown in Table 1.

[0049] Tensile shear strength test: The test was conducted according to the relevant provisions of GB / T 7124-2008. Specifically, a standard alumina alloy plate (100mm×25mm×2mm in size) that had been cleaned with acetone to remove oil was selected as the bonding substrate. The adhesives prepared in each example and comparative example were uniformly applied to the overlapping surfaces of the two aluminum plates, with the overlapping area controlled at 12.5mm×25mm and the thickness of the adhesive layer maintained at 0.5mm. The overlapping parts were fixed with positioning clamps and cured for 14 days at room temperature (23±2℃) and relative humidity (50±10%). The cured overlapping specimens were then transferred to a universal testing machine and subjected to tensile shear failure test at an axial speed of 5mm / min. The maximum shear force at which the specimen failed was recorded, as shown in Table 1.

[0050] Storage stability test: The adhesives prepared in each example and comparative example were placed in sealing tubes, sealed well, and stored continuously in a constant temperature drying oven at 50°C for 21 days. After the end of the period, they were taken out and placed in an environment with room temperature (23±2°C) and relative humidity (50±10%) to cool naturally to room temperature. The sealing tubes were then opened, and it was observed whether there was any solidified dead glue inside. For the glue that could still be extruded smoothly, its tensile strength was measured according to the tensile strength test method described above. The tensile strength retention rate after aging (strength after aging / strength before aging × 100%) was calculated. The results are shown in Table 1.

[0051] Table 1 Relevant performance test results

[0052] The test results of Example 1, Comparative Example 1 (without plasma activation of aramid chopped fibers), and Comparative Example 2 (without immersion of aramid chopped fibers in an alcohol solution containing silane coupling agent) show that when plasma treatment or coupling agent grafting is omitted, the tensile strength and shear strength of the adhesive decrease significantly. This indicates that aramid chopped fibers without physical etching or surface grafting modification cannot achieve good interfacial compatibility with the resin matrix under external force. The fibers easily slide out of the matrix as a whole, thus losing the ability to transfer stress to the high-modulus skeleton, resulting in a decline in performance. The test results of Example 1, Comparative Example 3 (without grafted aramid chopped fibers), and Comparative Example 4 (without added acrylate core-shell rubber particles) show that their elongation at break decreases sharply. This indicates that when the material is subjected to external force, the flexible acrylate core-shell rubber particles preferentially absorb most of the energy through crazing and shear banding, while the grafted aramid, as a rigid skeleton, can transfer the remaining stress. The synergistic effect of the two results in a material with both high strength and good elasticity. The test results of Example 1, Comparative Example 5, and Comparative Example 6 show that the stepwise addition of the dehydrating agent effectively prevents the introduction of moisture during the preparation process and improves the stability of the product.

[0053] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0054] Although embodiments of this application have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of this application, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method for preparing a high mechanical strength aramid-modified MS resin, characterized in that, Includes the following steps: S1. Aramid chopped fibers are activated by plasma under a mixed atmosphere and then placed in an alcohol solution containing silane coupling agent. After heating and reaction, they are washed and dried to obtain grafted aramid chopped fibers. S2. Using raw materials including grafted aramid short fibers, acrylate core-shell rubber particles, and silane-terminated polyether resin, aramid-modified MS resin is obtained by heating and shearing blending under an inert atmosphere.

2. The method for preparing a high mechanical strength aramid-modified MS resin according to claim 1, characterized in that, In step S1, the plasma activation process conditions are: discharge power of 200-300W, bombardment time of 10-15min; and the mixed atmosphere is a mixture of oxygen and argon in a volume ratio of 1:3-5.

3. The method for preparing a high mechanical strength aramid-modified MS resin according to claim 1, characterized in that, In step S1, the method for preparing the alcohol solution containing the silane coupling agent is as follows: the ratio of water, anhydrous ethanol, and silane coupling agent is 10:85-95: Anhydrous ethanol and deionized water are mixed at a mass ratio of 0.6-1. A silane coupling agent is then added to the mixture at a rotation speed of 200-300 r / min. After thorough mixing, the pH of the system is adjusted to 5.0, and the mixture is hydrolyzed at room temperature for 25-45 min to obtain the alcohol solution containing the silane coupling agent.

4. The method for preparing a high mechanical strength aramid-modified MS resin according to claim 1, characterized in that, In step S2, the mass ratio of silane-terminated polyether resin, grafted aramid chopped fiber, and acrylate core-shell rubber particles is 100:4-8:3-6.

5. A high mechanical strength aramid-modified MS resin, characterized in that, It was prepared using the preparation method of a high mechanical strength aramid modified MS resin as described in any one of claims 1-4.

6. A high mechanical strength aramid-modified MS resin adhesive, characterized in that, By weight, it comprises 35-50 parts of the aramid-modified MS resin as described in claim 5, 6-8 parts of plasticizer, 38-43 parts of inorganic filler, 1.8-2.2 parts of dehydrating agent, 2.5-3.5 parts of rheology and thixotropy agent, 0.6-0.8 parts of interfacial thickening accelerator, 0.6-0.8 parts of anti-aging additive, and 0.25-0.3 parts of catalyst.

7. The high mechanical strength aramid-modified MS resin adhesive according to claim 6, characterized in that, The inorganic filler is composed of heavy calcium carbonate and light calcium carbonate in a mass ratio of 1.3-1.5:

1.

8. The high mechanical strength aramid-modified MS resin adhesive according to claim 6, characterized in that, The interface thickening accelerator is a compound of at least two of the following: monoaminosilane coupling agents, diaminosilane coupling agents, and epoxysilane coupling agents.

9. A method for preparing a high mechanical strength aramid-modified MS resin adhesive according to any one of claims 6-8, characterized in that, The preparation process is as follows: Raw materials including aramid-modified MS resin, plasticizer, and a first-part dehydrating agent are added to a vacuum mixer. After stirring evenly under an inert atmosphere, raw materials including inorganic filler, rheology thixotropic agent, and anti-aging additive are added. The temperature is controlled at 42-48℃, the vacuum degree is -0.1MPa to -0.095MPa, and high-speed shear mixing is performed for 40-60 minutes. The temperature is then reduced to 30-33℃. Subsequently, raw materials including a second-part dehydrating agent, interfacial thickening promoter, and catalyst are added. The mixture is mixed and reacted under an inert atmosphere for 10-15 minutes. The temperature is then controlled at 25-30℃, the rotation speed is reduced to 100-200 r / min, and degassing is performed under vacuum for 10-15 minutes to obtain the adhesive.

10. The method for preparing a high mechanical strength aramid-modified MS resin adhesive according to claim 9, characterized in that, The first part, the dehydrating agent, accounts for 60%-70% of the total mass of the dehydrating agent.

Images