Reactive polyacrylate elastomer, preparation method thereof and application of reactive polyacrylate elastomer in toughening epoxy resin

Abstract

The invention discloses a reactive polyacrylate elastomer, a preparation method thereof and application of the reactive polyacrylate elastomer in toughening epoxy resin. The reactive polyacrylate elastomer is prepared from the following raw materials: a soft monomer, a hard monomer, a functional monomer, an initiator and an organic solvent. The reactive polyacrylate elastomer is synthesized by simultaneously introducing active functional groups of carboxyl and hydroxyl into a molecular chain of the polyacrylate elastomer through a solution polymerization method, and after the elastomer is mixed with epoxy resin, the carboxyl and the hydroxyl on the elastomer chain can chemically react with epoxy groups in the curing process, so that the epoxy resin can be cured, and the curing time is shortened. According to the present invention, the elastomer particles are added to the epoxy resin matrix, such that the firm chemical bond connection is formed between the elastomer particles and the epoxy resin matrix so as to significantly improve the two-phase interface bonding force, such that the impact strength and the fracture toughness of the cured epoxy resin can be substantially improved by more than 100%, and the bending strength, the modulus, the glass transition temperature and other core performances of the cured epoxy resin can be substantially not reduced.

Description

Technical Field

[0001] This invention belongs to the field of polymer material modification technology, and relates to a method for toughening epoxy resin, specifically to a reactive polyacrylate elastomer, its preparation method, and its application in toughening epoxy resin. Background Technology

[0002] Epoxy resins, as important thermosetting polymers, play an irreplaceable role in aerospace, electronic packaging, composite materials, high-performance adhesives, and coatings due to their excellent mechanical strength, adhesive properties, chemical resistance, and dimensional stability. However, while their highly cross-linked three-dimensional network structure endows them with high modulus and high strength, it also leads to significant drawbacks such as intrinsic brittleness, poor impact resistance, and insufficient crack propagation resistance, severely limiting their application in harsh working conditions.

[0003] Overcoming the brittleness of epoxy resins through toughening modification has always been a key research focus and challenge in this field. Currently, widely used toughening methods include:

[0004] (1) Add rubber elastomer (such as carboxyl-terminated butadiene nitrile rubber CTBN).

[0005] (2) Introduce thermoplastics (such as polyethersulfone PES, polyetherimide PEI);

[0006] (3) Constructing an interpenetrating polymer network (IPN);

[0007] (4) Add inorganic nanoparticles, etc.

[0008] Among these methods, rubber elastomer toughening is the most commonly used due to its significant effects and relatively simple process. However, traditional rubber toughening systems, especially physically blended non-reactive elastomers, have the following inherent drawbacks:

[0009] (1) Poor compatibility and phase separation: Most rubbers have poor compatibility with epoxy resin matrix. During the curing process, macroscopic or microscopic phase separation is likely to occur, resulting in uneven dispersion and excessive size of elastomer particles, forming stress defect centers.

[0010] (2) Weak interfacial bonding: Due to the lack of effective chemical bonding, the interfacial bonding between the rubber phase and the epoxy resin phase is weak. When subjected to external force, the interface is prone to debonding, resulting in premature propagation of crevice and cracks, and low toughening efficiency.

[0011] (3) Sacrificing rigidity and heat resistance: In order to obtain a certain toughening effect, a large amount of elastomer is usually required. This often severely dilutes the crosslinking density of epoxy resin, resulting in a significant decrease in the modulus, strength and glass transition temperature (Tg) of the material, falling into the dilemma of "toughening inevitably reduces strength".

[0012] Polyacrylate elastomers possess excellent weather resistance, aging resistance, and mechanical properties, making them potential ideal toughening agents. However, simply blending them as non-reactive components cannot avoid the aforementioned drawbacks. Therefore, developing a reactive polyacrylate toughening agent that can form strong interfacial chemical bonds with the epoxy resin matrix, achieving efficient toughening without compromising its inherent superior properties, has become crucial to overcoming current technological bottlenecks. Summary of the Invention

[0013] To address the technical problems of poor interfacial compatibility, low toughening efficiency, and decreased matrix strength and modulus in traditional epoxy resin toughening with elastomers, this invention provides a reactive polyacrylate elastomer, its preparation method, and its application in epoxy resin toughening. This invention synthesizes a reactive polyacrylate elastomer by simultaneously introducing carboxyl groups (such as acrylic acid) and hydroxyl groups (such as hydroxyethyl methacrylate) into the molecular chain of the polyacrylate elastomer through solution polymerization. When this elastomer is mixed with epoxy resin, during the curing process, the carboxyl and hydroxyl groups on the elastomer chain can chemically react with the epoxy groups, thereby forming strong chemical bonds between the elastomer particles and the epoxy resin matrix. This significantly improves the interfacial bonding force, resulting in a more than 100% increase in impact strength and fracture toughness of the cured epoxy resin while maintaining its core properties such as flexural strength, modulus, and glass transition temperature with minimal decrease, achieving a good balance between high strength and high toughness. This invention has a simple process and is suitable for high-performance toughening modification of epoxy resins.

[0014] The objective of this invention is achieved through the following technical solution:

[0015] A reactive polyacrylate elastomer comprises the following raw materials in parts by weight: 50-65 parts of soft monomer, 30-45 parts of hard monomer, 5-20 parts of functional monomer, 0.1-0.5 parts of initiator, and 50-300 parts of organic solvent, wherein:

[0016] The soft monomer is one or more of ethyl acrylate, butyl acrylate, isooctyl acrylate, and lauryl methacrylate;

[0017] The hard monomer is one or more of methyl methacrylate, vinyl acetate, tert-butyl acrylate, and isobornyl methacrylate.

[0018] The functional monomers are several of the following: acrylic acid, hydroxybutyl acrylate, hydroxyethyl acrylate, and glycidyl methacrylate.

[0019] The initiator is one or more of benzoyl peroxide, azobisisobutyronitrile, azobisisovalerate, and azobisisoheptanenitrile;

[0020] The organic solvent is a mixture of ethyl acetate, toluene, and isopropanol.

[0021] A method for preparing the above-mentioned reactive polyacrylate elastomer includes the following steps:

[0022] Step 1: Mix the soft monomers, hard monomers and functional monomers into a mixture, and divide the mixture into part a (40-60%) and part b (40-60%) by mass percentage.

[0023] Step 2: Add 30-50% ethyl acetate to the reactor in part a and stir, controlling the stirring speed to 100-150 r / min;

[0024] Step 3: Add 20-40% ethyl acetate, toluene, isopropanol and 47-53% initiator to part b, stir evenly and then add to the high-level dropping tank 1, controlling the stirring speed to 100-150 r / min;

[0025] Step 4: Mix 5-15% ethyl acetate and 12-18% initiator and place them in the high-level dropping tank 2, controlling the stirring speed to be 100-150 r / min;

[0026] Step 5: Introduce nitrogen into the reactor. When the reactor temperature reaches 60~80℃, add the well-mixed solution from the high-level dropping tank 2 into the reactor and continue heating until the reactor reaches the explosive polymerization state (at reflux temperature), then stop heating.

[0027] Step 6: After waiting for the reaction temperature to stabilize for 5-15 minutes, start titrating the mixed solution in the high-level dropping tank 1 at a uniform rate and complete the addition within 60-90 minutes. Then keep it warm for 2-4 hours. After that, add the remaining initiator and 5-15% ethyl acetate, titrate at a uniform rate and complete the addition within 30-60 minutes, and continue to keep it warm for 5-8 hours.

[0028] Step 7: Add the remaining ethyl acetate, cool to ≤45℃, and finally stir to obtain the reactive polyacrylate elastomer. The stirring speed is 200~300r / min.

[0029] An application of the above-mentioned reactive polyacrylate elastomer in toughened epoxy resin, including the specific application method and the steps for curing and preparing test samples, is as follows:

[0030] Step A1: By weight, 80-100 parts of epoxy resin and 20-50 parts of reactive polyacrylate elastomer are mixed and added to a round-bottom flask. The mixture is heated to 40-60°C and stirred for 60-120 minutes to form a homogeneous prepolymer. The epoxy resin is one or more of bisphenol A type epoxy resin, bisphenol F type epoxy resin, phenolic epoxy resin and alicyclic epoxy resin. The stirring speed is 200-300 r / min.

[0031] Step A2: Place the prepolymer under vacuum at 80~100℃ and slowly evaporate the organic solvent. After observing that no more bubbles emerge from the system and the weight no longer decreases, the acrylate elastomer is obtained. Then, place the acrylate elastomer in a vacuum drying oven for degassing treatment for 10~20 minutes to remove a small amount of air bubbles, and then obtain the epoxy resin system.

[0032] Step A3: Pour the degassed epoxy resin system into a preheated polytetrafluoroethylene mold, perform a phased curing process, and then allow it to cool naturally to room temperature before demolding to obtain the test sample. The preheating temperature is 80℃, and the phased curing process is: 80℃ / 2 hours + 100℃ / 2 hours + 120℃ / 2 hours.

[0033] Compared with the prior art, the present invention has the following advantages:

[0034] 1. Achieving High Efficiency and Synergistic Toughening of Epoxy Resin: This invention, through molecular design, simultaneously introduces active functional groups containing carboxyl and hydroxyl groups during the synthesis of high molecular weight polyacrylate elastomers. During the epoxy resin curing process, this toughening agent not only induces and terminates crazes and shear bands by forming a uniformly distributed "island" structure through phase separation, thus consuming impact energy, but its active functional groups also chemically react with epoxy groups, constructing a strong chemical bridge between the elastomer particles and the epoxy resin matrix. This synergistic effect of physical dispersion and chemical bonding greatly improves toughening efficiency, resulting in a significant increase in the impact strength and fracture toughness of the epoxy resin.

[0035] 2. Perfectly Resolving the Contradiction Between "Toughening" and "Strength Reduction": Because the active elastomer becomes part of the epoxy crosslinking network through chemical bonds, it forms a strong "interfacial anchoring" effect and interpenetrating network structure, greatly enhancing the two-phase interface. This strong interface ensures that stress can be effectively transferred from the continuous phase to the dispersed phase, thus avoiding performance loss due to interfacial debonding while the elastomer efficiently exerts its toughening effect. Ultimately, the toughened epoxy resin composite material achieves ultra-high toughness while maintaining or even improving its rigidity indicators such as tensile strength, flexural strength, and modulus, successfully breaking through the bottleneck faced by traditional toughening technologies.

[0036] 3. Excellent compatibility and dispersion stability: The carboxyl and hydroxyl segments significantly improve the solubility and compatibility of polyacrylate elastomers in epoxy resin prepolymers, ensuring uniform and stable dispersion at the nano or micron level in the curing precursor. This lays a solid foundation for the formation of regular and stable toughened microstructures and avoids phase separation problems during storage and processing.

[0037] 4. Wide process adaptability and broad application prospects: The synthesis process of this toughening agent is mature and controllable. Its application can be directly integrated into the existing epoxy resin processing flow without special equipment. It is suitable for various molding processes such as casting, impregnation, molding and composite material prepregs. It has extremely high application value in the fields of electronic packaging, structural adhesives, and high-performance composite materials. Detailed Implementation

[0038] The technical solution of the present invention will be further described below with reference to the embodiments, but it is not limited thereto. Any modifications or equivalent substitutions to the technical solution of the present invention without departing from the spirit and scope of the technical solution of the present invention should be covered within the protection scope of the present invention.

[0039] Example 1:

[0040] In this embodiment, the reactive polyacrylate elastomer comprises the following raw materials in parts by weight: 50 parts soft monomer, 30 parts hard monomer, 15 parts functional monomer, 0.3 parts initiator, and 200 parts organic solvent, wherein: the soft monomer is isooctyl acrylate, the hard monomer is methyl acrylate, the functional monomer is a mixture of acrylic acid (10 parts), hydroxyethyl acrylate (4.5 parts), and glycidyl methacrylate (0.5 parts), the initiator is azobisisobutyronitrile, and the organic solvent is a mixture of ethyl acetate (140 parts), isopropanol (30 parts), and methanol (30 parts). The specific preparation steps are as follows:

[0041] Step 1: Mix the soft monomer, hard monomer and functional monomer into a mixture, and divide the mixture into part a (40%) and part b (60%) by mass percentage.

[0042] Step 2: Add 40% ethyl acetate to the reactor in part a and stir at a speed of 110 r / min;

[0043] Step 3: Add 30% ethyl acetate, isopropanol, methanol and 50% initiator to part b, stir evenly and then add to high-level dropping tank 1. Stir at 110 r / min.

[0044] Step 4: Mix 10% ethyl acetate and 15% initiator and place them in the high-level dropping tank 2. Stir at a speed of 110 r / min.

[0045] Step 5: Introduce nitrogen into the reactor. When the reactor temperature reaches 60°C, add the well-mixed solution from the high-level dropping tank 2 into the reactor and continue heating until the reactor reaches the explosive polymerization state (at reflux temperature), then stop heating.

[0046] Step 6: After waiting for the reaction temperature to stabilize for 10 minutes, start the uniform titration of the mixed solution in the high-level dropping tank 1 and complete the titration within 90 minutes. Then keep it at the temperature for 3 hours. Then add 35% initiator and 5% ethyl acetate, titrate uniformly and complete the titration within 30 minutes, and continue to keep it at the temperature for 6 hours.

[0047] Step 7: Add 15% ethyl acetate, cool to 45℃, and finally stir to obtain reactive polyacrylate elastomer at a stirring speed of 250 r / min.

[0048] A method for applying the above-mentioned reactive polyacrylate elastomer in toughened epoxy resin and a method for curing and preparing test samples include the following steps:

[0049] Step A1: By weight, 100 parts of epoxy resin (bisphenol A type epoxy resin, E51) and 20 parts of reactive polyacrylate elastomer are mixed and added to a round bottom flask, heated to 60°C and stirred for 90 min to form a uniform prepolymer. The stirring speed is 250 r / min.

[0050] Step A2: Place the prepolymer under vacuum at 80°C and slowly evaporate the organic solvent. After observing that no more bubbles emerge from the system and the weight no longer decreases, the acrylate elastomer is obtained. Then, place the acrylate elastomer in a vacuum drying oven for degassing treatment for 15 minutes to remove a small amount of air bubbles, and then obtain the epoxy resin system.

[0051] Step A3: Pour the degassed epoxy resin system into a preheated polytetrafluoroethylene mold, perform a phased curing process, and then allow it to cool naturally to room temperature before demolding to obtain the test sample. The preheating temperature is 80℃, and the phased curing process is: 80℃ / 2 hours + 100℃ / 2 hours + 120℃ / 2 hours.

[0052] Example 2:

[0053] In this embodiment, the reactive polyacrylate elastomer comprises the following raw materials in parts by weight: 50 parts soft monomer, 30 parts hard monomer, 15 parts functional monomer, 0.3 parts initiator, and 200 parts organic solvent. The soft monomer is isooctyl acrylate, the hard monomer is methyl acrylate, the functional monomer is a mixture of acrylic acid (10 parts), hydroxyethyl acrylate (4.5 parts), and glycidyl methacrylate (0.5 parts), the initiator is azobisisobutyronitrile, and the organic solvent is a mixture of ethyl acetate (140 parts), isopropanol (30 parts), and methanol (30 parts). The specific preparation steps are as follows:

[0054] Step 1: Mix the soft monomer, hard monomer and functional monomer into a mixture, and divide the mixture into part a (40%) and part b (60%) by mass percentage.

[0055] Step 2: Add 40% ethyl acetate to the reactor in part a and stir at a speed of 110 r / min;

[0056] Step 3: Add 30% ethyl acetate, isopropanol, methanol and 50% initiator to part b, stir evenly and then add to high-level dropping tank 1. Stir at 110 r / min.

[0057] Step 4: Mix 10% ethyl acetate and 15% initiator and place them in the high-level dropping tank 2. Stir at a speed of 110 r / min.

[0058] Step 5: Introduce nitrogen into the reactor. When the reactor temperature reaches 60°C, add the well-mixed solution from the high-level dropping tank 2 into the reactor and continue heating until the reactor reaches the explosive polymerization state (at reflux temperature), then stop heating.

[0059] Step 6: After waiting for the reaction temperature to stabilize for 10 minutes, start the uniform titration of the mixed solution in the high-level dropping tank 1 and complete the titration within 90 minutes. Then keep it at the temperature for 3 hours. Then add 35% initiator and 5% ethyl acetate, titrate uniformly and complete the titration within 30 minutes, and continue to keep it at the temperature for 6 hours.

[0060] Step 7: Add 15% ethyl acetate, cool to 45℃, and finally stir to obtain reactive polyacrylate elastomer at a stirring speed of 250 r / min.

[0061] A method for applying the above-mentioned reactive polyacrylate elastomer in toughened epoxy resin and a method for curing and preparing test samples include the following steps:

[0062] Step A1: By weight, 100 parts of epoxy resin (bisphenol A type epoxy resin, E51) and 30 parts of reactive polyacrylate elastomer are mixed and added to a round bottom flask, heated to 60°C and stirred for 90 min to form a uniform prepolymer. The stirring speed is 250 r / min.

[0063] Step A2: Place the prepolymer under vacuum at 80°C and slowly evaporate the organic solvent. After observing that no more bubbles emerge from the system and the weight no longer decreases, the acrylate elastomer is obtained. Then, place the acrylate elastomer in a vacuum drying oven for degassing treatment for 15 minutes to remove a small amount of air bubbles, and then obtain the epoxy resin system.

[0064] Step A3: Pour the degassed epoxy resin system into a preheated polytetrafluoroethylene mold, perform a phased curing process, and then allow it to cool naturally to room temperature before demolding to obtain the test sample. The preheating temperature is 80℃, and the phased curing process is: 80℃ / 2 hours + 100℃ / 2 hours + 120℃ / 2 hours.

[0065] Example 3:

[0066] In this embodiment, the reactive polyacrylate elastomer comprises the following raw materials in parts by weight: 50 parts soft monomer, 30 parts hard monomer, 15 parts functional monomer, 0.3 parts initiator, and 200 parts organic solvent. The soft monomer is isooctyl acrylate, the hard monomer is methyl acrylate, the functional monomer is a mixture of acrylic acid (10 parts), hydroxyethyl acrylate (4.5 parts), and glycidyl methacrylate (0.5 parts), the initiator is azobisisobutyronitrile, and the organic solvent is a mixture of ethyl acetate (140 parts), isopropanol (30 parts), and methanol (30 parts). The specific preparation steps are as follows:

[0067] Step 1: Mix the soft monomer, hard monomer and functional monomer into a mixture, and divide the mixture into part a (40%) and part b (60%) by mass percentage.

[0068] Step 2: Add 40% ethyl acetate to the reactor in part a and stir at a speed of 110 r / min;

[0069] Step 3: Add 30% ethyl acetate, isopropanol, methanol and 50% initiator to part b, stir evenly and then add to high-level dropping tank 1. Stir at 110 r / min.

[0070] Step 4: Mix 10% ethyl acetate and 15% initiator and place them in the high-level dropping tank 2. Stir at a speed of 110 r / min.

[0071] Step 5: Introduce nitrogen into the reactor. When the reactor temperature reaches 60°C, add the well-mixed solution from the high-level dropping tank 2 into the reactor and continue heating until the reactor reaches the explosive polymerization state (at reflux temperature), then stop heating.

[0072] Step 6: After waiting for the reaction temperature to stabilize for 10 minutes, start the uniform titration of the mixed solution in the high-level dropping tank 1 and complete the titration within 90 minutes. Then keep it at the temperature for 3 hours. Then add 35% initiator and 5% ethyl acetate, titrate uniformly and complete the titration within 30 minutes, and continue to keep it at the temperature for 6 hours.

[0073] Step 7: Add 15% ethyl acetate, cool to 45℃, and finally stir to obtain reactive polyacrylate elastomer at a stirring speed of 250 r / min.

[0074] A method for applying the above-mentioned reactive polyacrylate elastomer in toughened epoxy resin and a method for curing and preparing test samples include the following steps:

[0075] Step A1: By weight, 100 parts of epoxy resin (bisphenol A type epoxy resin, E51) and 40 parts of reactive polyacrylate elastomer are mixed and added to a round bottom flask, heated to 60°C and stirred for 90 min to form a uniform prepolymer. The stirring speed is 250 r / min.

[0076] Step A2: Place the prepolymer under vacuum at 80°C and slowly evaporate the organic solvent. After observing that no more bubbles emerge from the system and the weight no longer decreases, the acrylate elastomer is obtained. Then, place the acrylate elastomer in a vacuum drying oven for degassing treatment for 15 minutes to remove a small amount of air bubbles, and then obtain the epoxy resin system.

[0077] Step A3: Pour the degassed epoxy resin system into a preheated polytetrafluoroethylene mold, perform a phased curing process, and then allow it to cool naturally to room temperature before demolding to obtain the test sample. The preheating temperature is 80℃, and the phased curing process is: 80℃ / 2 hours + 100℃ / 2 hours + 120℃ / 2 hours.

[0078] Example 4:

[0079] In this embodiment, the reactive polyacrylate elastomer comprises the following raw materials in parts by weight: 50 parts soft monomer, 30 parts hard monomer, 15 parts functional monomer, 0.3 parts initiator, and 200 parts organic solvent. The soft monomer is isooctyl acrylate, the hard monomer is methyl acrylate, the functional monomer is a mixture of acrylic acid (10 parts), hydroxyethyl acrylate (4.5 parts), and glycidyl methacrylate (0.5 parts), the initiator is azobisisobutyronitrile, and the organic solvent is a mixture of ethyl acetate (140 parts), isopropanol (30 parts), and methanol (30 parts). The specific preparation steps are as follows:

[0080] Step 1: Mix the soft monomer, hard monomer and functional monomer into a mixture, and divide the mixture into part a (40%) and part b (60%) by mass percentage.

[0081] Step 2: Add 40% ethyl acetate to the reactor in part a and stir at a speed of 110 r / min;

[0082] Step 3: Add 30% ethyl acetate, isopropanol, methanol and 50% initiator to part b, stir evenly and then add to high-level dropping tank 1. Stir at 110 r / min.

[0083] Step 4: Mix 10% ethyl acetate and 15% initiator and place them in the high-level dropping tank 2. Stir at a speed of 110 r / min.

[0084] Step 5: Introduce nitrogen into the reactor. When the reactor temperature reaches 60°C, add the well-mixed solution from the high-level dropping tank 2 into the reactor and continue heating until the reactor reaches the explosive polymerization state (at reflux temperature), then stop heating.

[0085] Step 6: After waiting for the reaction temperature to stabilize for 10 minutes, start the uniform titration of the mixed solution in the high-level dropping tank 1 and complete the titration within 90 minutes. Then keep it at the temperature for 3 hours. Then add 35% initiator and 5% ethyl acetate, titrate uniformly and complete the titration within 30 minutes, and continue to keep it at the temperature for 6 hours.

[0086] Step 7: Add 15% ethyl acetate, cool to 45℃, and finally stir to obtain reactive polyacrylate elastomer at a stirring speed of 250 r / min.

[0087] A method for applying the above-mentioned reactive polyacrylate elastomer in toughened epoxy resin and a method for curing and preparing test samples include the following steps:

[0088] Step A1: By weight, 100 parts of epoxy resin (bisphenol A type epoxy resin, E51) and 50 parts of reactive polyacrylate elastomer are mixed and added to a round bottom flask, heated to 60°C and stirred for 90 min to form a uniform prepolymer. The stirring speed is 250 r / min.

[0089] Step A2: Place the prepolymer under vacuum at 80°C and slowly evaporate the organic solvent. After observing that no more bubbles emerge from the system and the weight no longer decreases, the acrylate elastomer is obtained. Then, place the acrylate elastomer in a vacuum drying oven for degassing treatment for 15 minutes to remove a small amount of air bubbles, and then obtain the epoxy resin system.

[0090] Step A3: Pour the degassed epoxy resin system into a preheated polytetrafluoroethylene mold, perform a phased curing process, and then allow it to cool naturally to room temperature before demolding to obtain the test sample. The preheating temperature is 80℃, and the phased curing process is: 80℃ / 2 hours + 100℃ / 2 hours + 120℃ / 2 hours.

[0091] Example 5:

[0092] In this embodiment, the reactive polyacrylate elastomer comprises the following raw materials in parts by weight: 50 parts soft monomer, 30 parts hard monomer, 15 parts functional monomer, 0.3 parts initiator, and 200 parts organic solvent. The soft monomer is isooctyl acrylate, the hard monomer is methyl acrylate, the functional monomer is a mixture of acrylic acid (7.25 parts), hydroxyethyl acrylate (7.25 parts), and glycidyl methacrylate (0.5 parts), the initiator is azobisisobutyronitrile, and the organic solvent is a mixture of ethyl acetate (140 parts), isopropanol (30 parts), and methanol (30 parts). The specific preparation steps are as follows:

[0093] Step 1: Mix the soft monomer, hard monomer and functional monomer into a mixture, and divide the mixture into part a (40%) and part b (60%) by mass percentage.

[0094] Step 2: Add 40% ethyl acetate to the reactor in part a and stir at a speed of 110 r / min;

[0095] Step 3: Add 30% ethyl acetate, isopropanol, methanol and 50% initiator to part b, stir evenly and then add to high-level dropping tank 1. Stir at 110 r / min.

[0096] Step 4: Mix 10% ethyl acetate and 15% initiator and place them in the high-level dropping tank 2. Stir at a speed of 110 r / min.

[0097] Step 5: Introduce nitrogen into the reactor. When the reactor temperature reaches 60°C, add the well-mixed solution from the high-level dropping tank 2 into the reactor and continue heating until the reactor reaches the explosive polymerization state (at reflux temperature), then stop heating.

[0098] Step 6: After waiting for the reaction temperature to stabilize for 10 minutes, start the uniform titration of the mixed solution in the high-level dropping tank 1 and complete the titration within 90 minutes. Then keep it at the temperature for 3 hours. Then add 35% initiator and 5% ethyl acetate, titrate uniformly and complete the titration within 30 minutes, and continue to keep it at the temperature for 6 hours.

[0099] Step 7: Add 15% ethyl acetate, cool to 45℃, and finally stir to obtain reactive polyacrylate elastomer at a stirring speed of 250 r / min.

[0100] A method for applying the above-mentioned reactive polyacrylate elastomer in toughened epoxy resin and a method for curing and preparing test samples include the following steps:

[0101] Step A1: By weight, 100 parts of epoxy resin (bisphenol A type epoxy resin, E51) and 40 parts of reactive polyacrylate elastomer are mixed and added to a round bottom flask, heated to 60°C and stirred for 90 min to form a uniform prepolymer. The stirring speed is 250 r / min.

[0102] Step A2: Place the prepolymer under vacuum at 80°C and slowly evaporate the organic solvent. After observing that no more bubbles emerge from the system and the weight no longer decreases, the acrylate elastomer is obtained. Then, place the acrylate elastomer in a vacuum drying oven for degassing treatment for 15 minutes to remove a small amount of air bubbles, and then obtain the epoxy resin system.

[0103] Step A3: Pour the degassed epoxy resin system into a preheated polytetrafluoroethylene mold, perform a phased curing process, and then allow it to cool naturally to room temperature before demolding to obtain the test sample. The preheating temperature is 80℃, and the phased curing process is: 80℃ / 2 hours + 100℃ / 2 hours + 120℃ / 2 hours.

[0104] Example 6:

[0105] In this embodiment, the reactive polyacrylate elastomer comprises the following raw materials in parts by weight: 50 parts soft monomer, 30 parts hard monomer, 15 parts functional monomer, 0.3 parts initiator, and 200 parts organic solvent. The soft monomer is isooctyl acrylate, the hard monomer is methyl acrylate, the functional monomer is a mixture of acrylic acid (4.5 parts), hydroxyethyl acrylate (10 parts), and glycidyl methacrylate (0.5 parts), the initiator is azobisisobutyronitrile, and the organic solvent is a mixture of ethyl acetate (140 parts), isopropanol (30 parts), and methanol (30 parts). The specific preparation steps are as follows:

[0106] Step 1: Mix the soft monomer, hard monomer and functional monomer into a mixture, and divide the mixture into part a (40%) and part b (60%) by mass percentage.

[0107] Step 2: Add 40% ethyl acetate to the reactor in part a and stir at a speed of 110 r / min;

[0108] Step 3: Add 30% ethyl acetate, isopropanol, methanol and 50% initiator to part b, stir evenly and then add to high-level dropping tank 1. Stir at 110 r / min.

[0109] Step 4: Mix 10% ethyl acetate and 15% initiator and place them in the high-level dropping tank 2. Stir at a speed of 110 r / min.

[0110] Step 5: Introduce nitrogen into the reactor. When the reactor temperature reaches 60°C, add the well-mixed solution from the high-level dropping tank 2 into the reactor and continue heating until the reactor reaches the explosive polymerization state (at reflux temperature), then stop heating.

[0111] Step 6: After waiting for the reaction temperature to stabilize for 10 minutes, start the uniform titration of the mixed solution in the high-level dropping tank 1 and complete the titration within 90 minutes. Then keep it at the temperature for 3 hours. Then add 35% initiator and 5% ethyl acetate, titrate uniformly and complete the titration within 30 minutes, and continue to keep it at the temperature for 6 hours.

[0112] Step 7: Add 15% ethyl acetate, cool to 45℃, and finally stir to obtain reactive polyacrylate elastomer at a stirring speed of 250 r / min.

[0113] A method for applying the above-mentioned reactive polyacrylate elastomer in toughened epoxy resin and a method for curing and preparing test samples include the following steps:

[0114] Step A1: By weight, 100 parts of epoxy resin (bisphenol A type epoxy resin, E51) and 40 parts of reactive polyacrylate elastomer are mixed and added to a round bottom flask, heated to 60°C and stirred for 90 min to form a uniform prepolymer. The stirring speed is 250 r / min.

[0115] Step A2: Place the prepolymer under vacuum at 80°C and slowly evaporate the organic solvent. After observing that no more bubbles emerge from the system and the weight no longer decreases, the acrylate elastomer is obtained. Then, place the acrylate elastomer in a vacuum drying oven for degassing treatment for 15 minutes to remove a small amount of air bubbles, and then obtain the epoxy resin system.

[0116] Step A3: Pour the degassed epoxy resin system into a preheated polytetrafluoroethylene mold, perform a phased curing process, and then allow it to cool naturally to room temperature before demolding to obtain the test sample. The preheating temperature is 80℃, and the phased curing process is: 80℃ / 2 hours + 100℃ / 2 hours + 120℃ / 2 hours.

[0117] Example 7:

[0118] In this embodiment, the reactive polyacrylate elastomer comprises the following raw materials in parts by weight: 55 parts soft monomer, 45 parts hard monomer, 10 parts functional monomer, 0.4 parts initiator, and 100 parts organic solvent. The soft monomer is isooctyl acrylate, the hard monomer is methyl acrylate, the functional monomer is a mixture of acrylic acid (7 parts), hydroxyethyl acrylate (2.5 parts), and glycidyl methacrylate (0.5 parts), the initiator is azobisisobutyronitrile, and the organic solvent is a mixture of ethyl acetate (70 parts), isopropanol (15 parts), and methanol (15 parts). The specific preparation steps are as follows:

[0119] Step 1: Mix the soft monomer, hard monomer and functional monomer into a mixture, and divide the mixture into part a (40%) and part b (60%) by mass percentage.

[0120] Step 2: Add 40% ethyl acetate to the reactor in part a and stir at a speed of 110 r / min;

[0121] Step 3: Add 30% ethyl acetate, isopropanol, methanol and 50% initiator to part b, stir evenly and then add to high-level dropping tank 1. Stir at 110 r / min.

[0122] Step 4: Mix 10% ethyl acetate and 15% initiator and place them in the high-level dropping tank 2. Stir at a speed of 110 r / min.

[0123] Step 5: Introduce nitrogen into the reactor. When the reactor temperature reaches 60°C, add the well-mixed solution from the high-level dropping tank 2 into the reactor and continue heating until the reactor reaches the explosive polymerization state (at reflux temperature), then stop heating.

[0124] Step 6: After waiting for the reaction temperature to stabilize for 10 minutes, start the uniform titration of the mixed solution in the high-level dropping tank 1 and complete the titration within 90 minutes. Then keep it at the temperature for 3 hours. Then add 35% initiator and 5% ethyl acetate, titrate uniformly and complete the titration within 30 minutes, and continue to keep it at the temperature for 6 hours.

[0125] Step 7: Add 15% ethyl acetate, cool to 45℃, and finally stir to obtain reactive polyacrylate elastomer at a stirring speed of 250 r / min.

[0126] A method for applying the above-mentioned reactive polyacrylate elastomer in toughened epoxy resin and a method for curing and preparing test samples include the following steps:

[0127] Step A1: By weight, 100 parts of epoxy resin (bisphenol A type epoxy resin, E51) and 40 parts of reactive polyacrylate elastomer are mixed and added to a round bottom flask, heated to 60°C and stirred for 90 min to form a uniform prepolymer. The stirring speed is 250 r / min.

[0128] Step A2: Place the prepolymer under vacuum at 80°C and slowly evaporate the organic solvent. After observing that no more bubbles emerge from the system and the weight no longer decreases, the acrylate elastomer is obtained. Then, place the acrylate elastomer in a vacuum drying oven for degassing treatment for 15 minutes to remove a small amount of air bubbles, and then obtain the epoxy resin system.

[0129] Step A3: Pour the degassed epoxy resin system into a preheated polytetrafluoroethylene mold, perform a phased curing process, and then allow it to cool naturally to room temperature before demolding to obtain the test sample. The preheating temperature is 80℃, and the phased curing process is: 80℃ / 2 hours + 100℃ / 2 hours + 120℃ / 2 hours.

[0130] Example 8:

[0131] In this embodiment, the reactive polyacrylate elastomer comprises the following raw materials in parts by weight: 60 parts soft monomer, 30 parts hard monomer, 15 parts functional monomer, 0.3 parts initiator, and 200 parts organic solvent. The soft monomer is ethyl acrylate, the hard monomer is vinyl acetate, the functional monomer is a mixture of acrylic acid (10 parts), hydroxyethyl acrylate (4.5 parts), and glycidyl methacrylate (0.5 parts), the initiator is azobisisobutyronitrile, and the organic solvent is a mixture of ethyl acetate (140 parts), isopropanol (30 parts), and methanol (30 parts). The specific preparation steps are as follows:

[0132] Step 1: Mix the soft monomer, hard monomer and functional monomer into a mixture, and divide the mixture into part a (40%) and part b (60%) by mass percentage.

[0133] Step 2: Add 40% ethyl acetate to the reactor in part a and stir at a speed of 110 r / min;

[0134] Step 3: Add 30% ethyl acetate, isopropanol, methanol and 50% initiator to part b, stir evenly and then add to high-level dropping tank 1. Stir at 110 r / min.

[0135] Step 4: Mix 10% ethyl acetate and 15% initiator and place them in the high-level dropping tank 2. Stir at a speed of 110 r / min.

[0136] Step 5: Introduce nitrogen into the reactor. When the reactor temperature reaches 60°C, add the well-mixed solution from the high-level dropping tank 2 into the reactor and continue heating until the reactor reaches the explosive polymerization state (at reflux temperature), then stop heating.

[0137] Step 6: After waiting for the reaction temperature to stabilize for 10 minutes, start the uniform titration of the mixed solution in the high-level dropping tank 1 and complete the titration within 90 minutes. Then keep it at the temperature for 3 hours. Then add 35% initiator and 5% ethyl acetate, titrate uniformly and complete the titration within 30 minutes, and continue to keep it at the temperature for 6 hours.

[0138] Step 7: Add 15% ethyl acetate, cool to 45℃, and finally stir to obtain reactive polyacrylate elastomer at a stirring speed of 250 r / min.

[0139] A method for applying the above-mentioned reactive polyacrylate elastomer in toughened epoxy resin and a method for curing and preparing test samples include the following steps:

[0140] Step A1: By weight, 100 parts of epoxy resin (bisphenol A type epoxy resin, E51) and 40 parts of reactive polyacrylate elastomer are mixed and added to a round bottom flask, heated to 60°C and stirred for 90 min to form a uniform prepolymer. The stirring speed is 250 r / min.

[0141] Step A2: Place the prepolymer under vacuum at 80°C and slowly evaporate the organic solvent. After observing that no more bubbles emerge from the system and the weight no longer decreases, the acrylate elastomer is obtained. Then, place the acrylate elastomer in a vacuum drying oven for degassing treatment for 15 minutes to remove a small amount of air bubbles, and then obtain the epoxy resin system.

[0142] Step A3: Pour the degassed epoxy resin system into a preheated polytetrafluoroethylene mold, perform a phased curing process, and then allow it to cool naturally to room temperature before demolding to obtain the test sample. The preheating temperature is 80℃, and the phased curing process is: 80℃ / 2 hours + 100℃ / 2 hours + 120℃ / 2 hours.

[0143] Example 9:

[0144] In this embodiment, the reactive polyacrylate elastomer comprises the following raw materials in parts by weight: 60 parts soft monomer, 40 parts hard monomer, 20 parts functional monomer, 0.3 parts initiator, and 150 parts organic solvent. The soft monomer is lauryl methacrylate, the hard monomer is isobornyl methacrylate, the functional monomer is a mixture of acrylic acid (12 parts), hydroxyethyl acrylate (6 parts), and glycidyl methacrylate (2 parts), the initiator is benzoyl peroxide, and the organic solvent is a mixture of ethyl acetate (110 parts), isopropanol (20 parts), and methanol (20 parts). The specific preparation steps are as follows:

[0145] Step 1: Mix the soft monomer, hard monomer and functional monomer into a mixture, and divide the mixture into part a (40%) and part b (60%) by mass percentage.

[0146] Step 2: Add 40% ethyl acetate to the reactor in part a and stir at a speed of 110 r / min;

[0147] Step 3: Add 30% ethyl acetate, isopropanol, methanol and 50% initiator to part b, stir evenly and then add to high-level dropping tank 1. Stir at 110 r / min.

[0148] Step 4: Mix 10% ethyl acetate and 15% initiator and place them in the high-level dropping tank 2. Stir at a speed of 110 r / min.

[0149] Step 5: Introduce nitrogen into the reactor. When the reactor temperature reaches 60°C, add the well-mixed solution from the high-level dropping tank 2 into the reactor and continue heating until the reactor reaches the explosive polymerization state (at reflux temperature), then stop heating.

[0150] Step 6: After waiting for the reaction temperature to stabilize for 10 minutes, start the uniform titration of the mixed solution in the high-level dropping tank 1 and complete the titration within 90 minutes. Then keep it at the temperature for 3 hours. Then add 35% initiator and 5% ethyl acetate, titrate uniformly and complete the titration within 30 minutes, and continue to keep it at the temperature for 6 hours.

[0151] Step 7: Add 15% ethyl acetate, cool to 45℃, and finally stir to obtain reactive polyacrylate elastomer at a stirring speed of 250 r / min.

[0152] A method for applying the above-mentioned reactive polyacrylate elastomer in toughened epoxy resin and a method for curing and preparing test samples include the following steps:

[0153] Step A1: By weight, 100 parts of epoxy resin (bisphenol A type epoxy resin, E51) and 40 parts of reactive polyacrylate elastomer are mixed and added to a round bottom flask, heated to 60°C and stirred for 90 min to form a uniform prepolymer. The stirring speed is 250 r / min.

[0154] Step A2: Place the prepolymer under vacuum at 80°C and slowly evaporate the organic solvent. After observing that no more bubbles emerge from the system and the weight no longer decreases, the acrylate elastomer is obtained. Then, place the acrylate elastomer in a vacuum drying oven for degassing treatment for 15 minutes to remove a small amount of air bubbles, and then obtain the epoxy resin system.

[0155] Step A3: Pour the degassed epoxy resin system into a preheated polytetrafluoroethylene mold, perform a phased curing process, and then allow it to cool naturally to room temperature before demolding to obtain the test sample. The preheating temperature is 80℃, and the phased curing process is: 80℃ / 2 hours + 100℃ / 2 hours + 120℃ / 2 hours.

[0156] Comparative Example 1:

[0157] In this comparative example, the epoxy resin curing system comprises the following raw materials in parts by weight: 100 parts epoxy resin and 30 parts traditional amine curing agent. The epoxy resin is a bisphenol A type epoxy resin, and the traditional amine curing agent is 4,4-diaminodiphenylmethane.

[0158] The preparation method of the above-mentioned epoxy resin system and the method for curing and preparing test samples include the following steps:

[0159] Step A1: Mix epoxy resin and traditional amine curing agent and add to a round-bottom flask. Heat to 40°C and stir for 90 minutes to form a uniform prepolymer. The stirring speed is 250 r / min.

[0160] Step A2: Place the prepolymer in a vacuum drying oven for degassing treatment for 15 minutes to remove air bubbles and obtain the epoxy resin system;

[0161] Step A3: Pour the degassed epoxy resin system into a preheated polytetrafluoroethylene mold, perform a phased curing process, and then allow it to cool naturally to room temperature before demolding to obtain the test sample. The preheating temperature is 80℃, and the phased curing process is: 80℃ / 2 hours + 100℃ / 2 hours + 120℃ / 2 hours.

[0162] Comparative Example 2:

[0163] In this comparative example, the epoxy resin curing system comprises the following raw materials in parts by weight: 100 parts epoxy resin and 30 parts traditional amine curing agent. The epoxy resin is a bisphenol A type epoxy resin, and the traditional amine curing agent is 4,4-diaminodiphenylmethane.

[0164] The preparation method of the above-mentioned epoxy resin system and the method for curing and preparing test samples include the following steps:

[0165] Step A1: Mix epoxy resin and traditional amine curing agent and add to a round-bottom flask. Heat to 40°C and stir for 90 minutes to form a uniform prepolymer. The stirring speed is 250 r / min.

[0166] Step A2: Place the prepolymer in a vacuum drying oven for degassing treatment for 15 minutes to remove air bubbles and obtain the epoxy resin system;

[0167] Step A3: Pour the degassed epoxy resin system into a preheated polytetrafluoroethylene mold, perform a phased curing process, and then allow it to cool naturally to room temperature before demolding to obtain the test sample. The preheating temperature is 80℃, and the phased curing process is: 80℃ / 2 hours + 100℃ / 1 hour + 120℃ / 1 hour + 160℃ / 2 hours.

[0168] Performance testing:

[0169] The epoxy resin systems prepared in Examples 1-6 and Comparative Examples 1-2 were used as samples and the following tests were performed respectively:

[0170] Glass transition temperature test: The glass transition temperature was measured using a dynamic thermomechanical analyzer, and the peak value of the loss modulus was recorded.

[0171] Impact strength test: The impact strength was determined using a simply supported beam impact testing machine according to GB / T 1043.1-2018 standard.

[0172] Fracture toughness test: The fracture toughness was determined using a universal testing machine according to GB / T 4161-2007 standard.

[0173] Bending strength test: The test was conducted using a universal testing machine in accordance with GB / T 9341-2008 standard.

[0174] Tensile properties test: The test was conducted using a universal testing machine in accordance with GB / T 1040.2-2006 standard.

[0175] Test results:

[0176] Detailed test results are shown in Table 1.

[0177]

[0178] As shown in Table 1, Comparative Example 1 did not fully cure under the conditions of "80℃ / 2 hours + 100℃ / 2 hours + 120℃ / 2 hours", but only completed curing under the conditions of "80℃ / 2 hours + 100℃ / 1 hour + 120℃ / 1 hour + 160℃ / 2 hours" (i.e., Comparative Example 2). This demonstrates that using polyacrylate elastomers for curing is a milder method and avoids the use of toxic, volatile small-molecule amine curing agents, making it more environmentally friendly and compliant with sustainable development requirements. In Example 6, the addition of excessive hydroxyethyl acrylate during the reaction process caused excessive chain segment entanglement, resulting in severe gelation.

[0179] A comparison of data from the examples and comparative examples reveals that, during the synthesis of high molecular weight polyacrylate elastomers, the simultaneous introduction of active functional groups containing carboxyl and hydroxyl groups allows the toughening agent to not only induce and terminate crazes and shear bands and dissipate impact energy during epoxy resin curing by forming a uniformly distributed "island" structure through phase separation, but also to chemically react with epoxy groups to build a strong chemical bridge between the elastomer particles and the epoxy resin matrix. This synergistic effect of physical dispersion and chemical bonding significantly improves toughening efficiency, resulting in a substantial increase in the impact strength and fracture toughness of the epoxy resin. Simultaneously, because the active elastomer becomes part of the epoxy crosslinking network through chemical bonds, a strong "interface anchoring" effect and interpenetrating network structure are formed, greatly enhancing the two-phase interface. This strong interface ensures that stress can be effectively transferred from the continuous phase to the dispersed phase, thus preventing performance loss due to interfacial debonding while allowing the elastomer to efficiently exert its toughening effect. Ultimately, the toughened epoxy resin composite material achieved ultra-high toughness while maintaining or even improving its rigidity indicators such as tensile strength, flexural strength, and modulus, successfully breaking through the bottleneck faced by traditional toughening technology.

Claims

1. A reactive polyacrylate elastomer, characterized in that... The reactive polyacrylate elastomer comprises the following raw materials in parts by weight: 50-65 parts of soft monomer, 30-45 parts of hard monomer, 5-20 parts of functional monomer, 0.1-0.5 parts of initiator, and 50-300 parts of organic solvent, wherein: the functional monomer is several of acrylic acid, hydroxybutyl acrylate, hydroxyethyl acrylate, and glycidyl methacrylate; and the organic solvent is a mixture of ethyl acetate, toluene, and isopropanol.

2. The reactive polyacrylate elastomer according to claim 1, characterized in that... The soft monomer is one or more of ethyl acrylate, butyl acrylate, isooctyl acrylate, and lauryl methacrylate.

3. The reactive polyacrylate elastomer according to claim 1, characterized in that... The hard monomer is one or more of methyl methacrylate, vinyl acetate, tert-butyl acrylate, and isobornyl methacrylate.

4. The reactive polyacrylate elastomer according to claim 1, characterized in that... The initiator is one or more of benzoyl peroxide, azobisisobutyronitrile, azobisisovalerate, and azobisisoheptanenitrile.

5. A method for preparing the reactive polyacrylate elastomer according to any one of claims 1-4, characterized in that... The method includes the following steps: Step 1: Mix the soft monomers, hard monomers and functional monomers into a mixture, and divide the mixture into part a (40-60%) and part b (40-60%) by mass percentage. Step 2: Add 30-50% ethyl acetate to the reactor in part a and stir, controlling the stirring speed to 100-150 r / min; Step 3: Add 20-40% ethyl acetate, toluene, isopropanol and 47-53% initiator to part b, stir well and then add to high-level dropping tank 1; Step 4: Mix 5-15% ethyl acetate and 12-18% initiator and place in high-level dropping tank 2; Step 5: Introduce nitrogen into the reactor. When the reactor temperature reaches 60~80℃, add the well-mixed solution from the high-level dropping tank 2 into the reactor and continue heating until the reactor reaches a state of explosive polymerization, then stop heating. Step 6: After waiting for the reaction temperature to stabilize for 5-15 minutes, start titrating the mixed solution in the high-level dropping tank 1 at a uniform rate and complete the addition within 60-90 minutes. Then keep it warm for 2-4 hours. After that, add the remaining initiator and 5-15% ethyl acetate, titrate at a uniform rate and complete the addition within 30-60 minutes, and continue to keep it warm for 5-8 hours. Step 7: Add the remaining ethyl acetate, cool to ≤45℃, and finally stir to obtain the reactive polyacrylate elastomer.

6. The method for preparing the reactive polyacrylate elastomer according to claim 5, characterized in that... In steps 3, 4 and 7, the stirring speed is controlled to be 100~150 r / min.

7. The use of the reactive polyacrylate elastomer according to any one of claims 1-4 in toughened epoxy resin.

8. The application of the reactive polyacrylate elastomer according to claim 7 in toughened epoxy resin, characterized in that... The specific preparation steps of the toughened epoxy resin are as follows: Step A1: By weight, add 80-100 parts of epoxy resin and 20-50 parts of reactive polyacrylate elastomer to a round-bottom flask, heat to 40-60℃ and stir for 60-120 minutes to form a homogeneous prepolymer. Step A2: Place the prepolymer under vacuum at 80~100℃ to slowly evaporate the organic solvent. After observing that no more bubbles emerge from the system and the weight no longer decreases, the acrylate elastomer is obtained. Then, place the acrylate elastomer in a vacuum drying oven for degassing treatment for 10~20 minutes to obtain the epoxy resin system. Step A3: Pour the degassed epoxy resin system into a preheated polytetrafluoroethylene mold, perform a phased curing process, and then allow it to cool naturally to room temperature before demolding to obtain the test sample.

9. The application of the reactive polyacrylate elastomer according to claim 7 in toughened epoxy resin, characterized in that... In step A1, the epoxy resin is one or more of bisphenol A type epoxy resin, bisphenol F type epoxy resin, phenolic epoxy resin and alicyclic epoxy resin, and the stirring speed is 200~300r / min.

10. The application of the reactive polyacrylate elastomer according to claim 7 in toughened epoxy resin, characterized in that... In step A3, the preheating temperature is 80℃, and the staged curing process is: 80℃ / 2 hours + 100℃ / 2 hours + 120℃ / 2 hours.

Images