Cured cross-linked rubber added with epoxy resin and preparation method of cured cross-linked rubber

Abstract

The invention relates to the technical field of curing agents, in particular to cured cross-linked rubber added with epoxy resin and a preparation method of the cured cross-linked rubber. The adhesive comprises the following components in parts by weight: 50-70 parts of epoxy resin, 20-40 parts of silicone rubber, 5-15 parts of a modified maleic dihydrazide curing agent, 2-8 parts of a dibenzoyl peroxide cross-linking agent, 5-15 parts of a carboxyl-terminated polybutadiene toughening agent, 5-20 parts of silicon dioxide filler and 5-10 parts of ethanol. Alpha, beta-unsaturated ketone compounds are added, and after the alpha, beta-unsaturated ketone compounds react with the maleic dihydrazide curing agent, new functional groups and chemical structures can be introduced into curing agent molecules, so that the flexibility of the curing agent molecules can be improved; the negative ions of the base catalyst can capture reactive hydrogen of maleic dihydrazide to form maleic dihydrazide negative ions with higher nucleophilicity, and the negative ions can perform nucleophilic addition on beta-carbon of the alpha, beta-unsaturated ketone compound more easily, so that the performance of the curing agent can be improved.

Description

Technical Field

[0001] The invention relates to the technical field of curing agents, in particular to a curing cross-linking rubber added with epoxy resin and a preparation method thereof. Background Art

[0002] Modern industry has increasingly stringent requirements on material performance in many modern industrial fields such as automobile manufacturing, aerospace, and electronic appliances. For example, the components around automobile engines require materials that can withstand high temperatures and chemical corrosion, while also having good shock absorption properties. The sealing materials in aerospace equipment must not only be able to maintain sealing effects at extreme temperatures, but also have sufficient strength and fatigue resistance. Traditional single materials (such as pure epoxy resin or rubber) are difficult to meet these complex and diverse performance requirements at the same time. Epoxy resin can provide good strength, hardness, chemical corrosion resistance, and dimensional stability; rubber gives the material flexibility, elasticity, and shock absorption properties. This combination enables the material to function under a wider range of environmental conditions and meet the needs of high-performance application scenarios.

[0003] After curing, epoxy resin forms a highly cross-linked network structure, which makes it hard, but also brittle. When subjected to impact or bending, its cured product is prone to cracks or even breaks. In practical applications, this brittleness may cause product damage. For example, in electronic packaging materials, brittle epoxy resin may crack when subjected to a slight collision, thereby affecting the performance and service life of electronic components. In view of this, we propose a cured cross-linked rubber with added epoxy resin and a preparation method thereof. Summary of the invention

[0004] The object of the present invention is to provide a cured cross-linked rubber with added epoxy resin and a preparation method thereof, so as to solve the problem raised in the above background technology that the cured product is prone to cracks or even breaks when subjected to impact or bending; in practical applications, such brittleness may cause product damage. For example, in electronic packaging materials, brittle epoxy resin may crack when subjected to a slight collision, thereby affecting the performance and service life of electronic components.

[0005] To achieve the above object, the present invention provides a curing cross-linking rubber with epoxy resin added, comprising the following components: 50-70 parts by weight of epoxy resin, 20-40 parts by weight of silicone rubber, 5-15 parts by weight of modified maleic acid dihydrazide curing agent, 2-8 parts by weight of dibenzoyl peroxide cross-linking agent, 5-15 parts by weight of terminal carboxyl polybutadiene toughening agent, 5-20 parts by weight of silica filler, and 5-10 parts by weight of ethanol; The modified maleic acid dihydrazide curing agent is prepared by Michael addition reaction of maleic acid dihydrazide and α,β-unsaturated ketone compound under alkaline catalyst; the α,β-unsaturated ketone compound is any one of methyl vinyl ketone and styryl acetone.

[0006] The preparation method of the modified maleic acid dihydrazide curing agent is as follows: S1.1. Weigh the following components in parts by weight respectively: 50-60 parts by weight of maleic acid dihydrazide curing agent, 30-40 parts by weight of α,β-unsaturated ketone compound, 2-5 parts by weight of base catalyst, and 10-20 parts by weight of ethanol; S1.2, dissolving the maleic acid dihydrazide curing agent and the alkaline catalyst in ethanol, stirring to fully dissolve; dripping the α,β-unsaturated ketone compound at a rate of 5-10 drops / minute, using an ice-water mixture to maintain the temperature at 0-5°C, to obtain a reaction mixture; There are active hydrogen atoms in the molecular structure of maleic acid dihydrazide. Alkaline catalysts can react with these active hydrogen atoms. The negative ions in the alkaline catalysts will capture the active hydrogen atoms of maleic acid dihydrazide to form maleic acid dihydrazide negative ions with stronger nucleophilicity. This negative ion is more nucleophilic than the original maleic acid dihydrazide molecule and is more likely to undergo nucleophilic addition to the β-carbon of α,β-unsaturated ketone compounds, laying the foundation for the subsequent improvement of the performance of the curing agent. There are multiple active hydrogen atoms in the maleic acid dihydrazide molecule, but under the action of the alkaline catalyst, the active hydrogen atoms at specific positions are more likely to be captured, and the formed nucleophilic reagent will preferentially undergo addition to the β-carbon of α,β-unsaturated ketone compounds, thereby improving the selectivity of the reaction at the target site and facilitating the generation of products with the expected structure.

[0007] S1.3, after the addition is completed, the reaction mixture is heated to room temperature, then heated to 40-60 ° C, stirred at a speed of 600-800 rpm, and nitrogen is introduced at a rate of 80-100 mL / min, and the reaction is continued for 9-12 hours; S1.4. After the reaction is completed, the reaction mixture is cooled to room temperature to allow the product to crystallize and then filtered; it is washed with deionized water to remove the residual catalyst and other impurities; after washing, it is freeze-dried to obtain a modified maleic acid dihydrazide curing agent.

[0008] After the α,β-unsaturated ketone compounds and maleic acid dihydrazide undergo Michael addition reaction, new functional groups are introduced into the molecular structure of the curing agent. These functional groups can change the electron cloud distribution of the curing agent molecules, thereby affecting their reactivity with epoxy resins. Better reactivity also helps to ensure complete curing of the material in complex molding processes, thereby improving the quality of cured cross-linked rubber products. The introduction of α,β-unsaturated ketone compounds increases the flexibility of the curing agent molecules. During the curing process, this flexibility can be transferred to the overall structure of the cured cross-linked rubber. When the material is impacted by external forces, the flexible segments in the cured product can absorb and disperse energy through deformation methods such as stretching and twisting, thereby avoiding stress concentration and causing material damage. When the modified curing agent participates in the curing reaction, it will affect the structure of the cured cross-linked network; the new structural units introduced by the α, β-unsaturated ketone compounds can change the density and distribution of the cross-linked points, making the cured cross-linked network more uniform and regular, which helps to improve the strength, hardness and dimensional stability of the material; at the same time, it can also improve the chemical corrosion resistance of the material, because the regular network structure can reduce the erosion path of chemical substances on the internal structure of the material.

[0009] Preferably, the base catalyst is any one of sodium ethoxide or potassium tert-butoxide.

[0010] Preferably, in S1.2, the stirring is performed by a stirrer at a speed of 300-400 rpm and a stirring time of 15-30 min.

[0011] Preferably, in S1.5, the drying temperature of freeze drying is -40 to -50°C, and the drying time is 4 to 6 hours.

[0012] On the other hand, the present invention provides a method for preparing a curable cross-linked rubber with epoxy resin added thereto, which is used for the curable cross-linked rubber with epoxy resin added thereto as described in any one of the above, comprising the following steps: S2.1, weigh the following components in parts by weight respectively: 50-70 parts by weight of epoxy resin, 20-40 parts by weight of silicone rubber, 5-15 parts by weight of modified maleic acid dihydrazide curing agent, 2-8 parts by weight of dibenzoyl peroxide crosslinking agent, 5-15 parts by weight of carboxyl-terminated polybutadiene toughening agent, 5-20 parts by weight of silica filler, and 5-10 parts by weight of ethanol; S2.2, add silicone rubber and silica filler into a stirrer, stir at 600-800 rpm for 10-15 min at room temperature until uniformly dispersed to obtain a premix; S2.3, add epoxy resin to the premix, stir at room temperature to make it fully mixed; add modified maleic acid dihydrazide curing agent, continue stirring at room temperature at a speed of 400-500rpm for 15-20min to ensure that it is evenly distributed in the mixture; S2.4 Dissolve dibenzoyl peroxide crosslinker in ethanol, add to the mixture, then add carboxyl-terminated polybutadiene toughening agent, and continue stirring at room temperature at a speed of 400-500 rpm for 5-10 minutes; S2.5. Pour the deaerated mixture into the mold, ensuring that it is evenly filled and free of bubbles; cure it under normal pressure for 6-12 hours; S2.6. After curing is completed, the mold is taken out and placed in the air to cool to room temperature to obtain a cured cross-linked rubber with added epoxy resin.

[0013] Preferably, the epoxy resin is any one of bisphenol F epoxy resin or polyethylene glycol diglycidyl ether.

[0014] Preferably, in S2.3, the stirring speed of adding the epoxy resin into the premix is ​​600-800 rpm, and the stirring time of adding the epoxy resin into the premix is ​​10-15 min.

[0015] Preferably, in S2.5, the degassing treatment is to place the mixture in a vacuum degassing machine with a vacuum degree of -0.08 to -0.1 MPa and a degassing time of 10 to 30 minutes to remove air bubbles introduced during the mixing process.

[0016] Preferably, in S2.5, the initial curing temperature is 60-80°C, the main curing temperature is 80-100°C, and the post-curing temperature is 120-150°C.

[0017] Compared with the prior art, the present invention has the following beneficial effects: 1. In the cured cross-linked rubber with added epoxy resin and its preparation method, α,β-unsaturated ketone compounds are added. After reacting with maleic acid dihydrazide curing agent, new functional groups and chemical structures are introduced into the curing agent molecules, which can increase the flexibility of the curing agent molecules. During the curing process, this flexibility can be transferred to the overall structure of the cured cross-linked rubber. When the material is impacted by external force, the flexible chain segments in the cured product can absorb and disperse energy through deformation modes such as stretching and twisting, thereby avoiding stress concentration and causing material damage.

[0018] 2. In the cured cross-linked rubber with added epoxy resin and its preparation method, an alkali catalyst is added because it plays a key activation role in the reaction of maleic acid dihydrazide and α, β-unsaturated ketone compounds; the negative ions in the alkali catalyst will capture the active hydrogen of maleic acid dihydrazide to form maleic acid dihydrazide negative ions with stronger nucleophilicity. This negative ion is more nucleophilic than the original maleic acid dihydrazide molecule and is more likely to perform nucleophilic addition on the β-carbon of the α, β-unsaturated ketone compound, thereby helping to improve the performance of the curing agent. DETAILED DESCRIPTION

[0019] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0020] The invention provides a curing cross-linking rubber added with epoxy resin, comprising the following components: 50-70 parts by weight of epoxy resin, 20-40 parts by weight of silicone rubber, 5-15 parts by weight of modified maleic acid dihydrazide curing agent, 2-8 parts by weight of dibenzoyl peroxide cross-linking agent, 5-15 parts by weight of terminal carboxyl polybutadiene toughening agent, 5-20 parts by weight of silicon dioxide filler, and 5-10 parts by weight of ethanol; The modified maleic acid dihydrazide curing agent is prepared by Michael addition reaction of maleic acid dihydrazide and α,β-unsaturated ketone compound under alkaline catalyst; the α,β-unsaturated ketone compound is styryl acetone.

[0021] The base catalyst is any one of sodium ethoxide or potassium tert-butoxide, and the base catalyst is preferably potassium tert-butoxide.

[0022] The epoxy resin is any one of bisphenol F epoxy resin and polyethylene glycol diglycidyl ether, and the epoxy resin is preferably bisphenol F epoxy resin.

[0023] Embodiment 1: Cured cross-linked rubber with epoxy resin added and preparation method thereof, comprising the following steps: S2.1, weigh the following components in parts by weight respectively: 60 parts by weight of bisphenol F epoxy resin, 30 parts by weight of silicone rubber, 10 parts by weight of modified maleic acid dihydrazide curing agent, 5 parts by weight of dibenzoyl peroxide crosslinking agent, 10 parts by weight of carboxyl-terminated polybutadiene toughening agent, 12 parts by weight of silica filler, and 8 parts by weight of ethanol; S2.2, add silicone rubber and silica filler into a stirrer, and stir at 800 rpm for 15 min at room temperature until uniformly dispersed to obtain a premix; S2.3, add bisphenol F epoxy resin to the premix, stir at room temperature, stirring speed of 600rpm, stirring time 15min, so that it is fully mixed; add modified maleic acid dihydrazide curing agent, continue stirring at room temperature at 400rpm speed for 15min, ensure that it is evenly distributed in the mixture; S2.4 Dissolve dibenzoyl peroxide crosslinker in ethanol, add to the mixture, then add carboxyl-terminated polybutadiene toughening agent, and continue stirring at room temperature at 400 rpm for 10 min; S2.5. Place the mixture in a vacuum degassing machine for degassing with a vacuum degree of -0.09 MPa and a degassing time of 30 min to remove air bubbles introduced during the mixing process; pour the degassing mixture into a mold to ensure uniform filling without bubbles; cure under normal pressure with an initial curing temperature of 70°C, a main curing temperature of 90°C, a post-curing temperature of 130°C, and a curing time of 12 h; S2.6. After curing is completed, the mold is taken out and placed in the air to cool to room temperature to obtain a cured cross-linked rubber with added epoxy resin.

[0024] The preparation method of the modified maleic acid dihydrazide curing agent is as follows: S1.1, weigh the following components in parts by weight respectively: 55 parts by weight of maleic acid dihydrazide curing agent, 30 parts by weight of styryl acetone, 4 parts by weight of potassium tert-butoxide, and 15 parts by weight of ethanol; S1.2, dissolving maleic acid dihydrazide curing agent and potassium tert-butoxide in ethanol, stirring with a stirrer at a speed of 300 rpm for 30 minutes to fully dissolve them; dripping styryl acetone at a rate of 6 drops / minute, using an ice-water mixture to maintain the temperature at 4°C, to obtain a reaction mixture; S1.3, after the addition was completed, the reaction mixture was warmed to room temperature, then heated to 60°C, stirred at 600 rpm, and nitrogen was introduced at a rate of 100 mL / min, and the reaction was continued for 12 h; S1.4. After the reaction is completed, the reaction mixture is cooled to room temperature to allow the product to crystallize and then filtered; it is washed with deionized water to remove the residual catalyst and other impurities; after washing, it is freeze-dried at a drying temperature of -40°C and a drying time of 6 hours to obtain a modified maleic acid dihydrazide curing agent.

[0025] Embodiment 2: Cured cross-linked rubber with epoxy resin added and preparation method thereof, comprising the following steps: S2.1, weigh the following components in parts by weight respectively: 60 parts by weight of bisphenol F epoxy resin, 30 parts by weight of silicone rubber, 10 parts by weight of modified maleic acid dihydrazide curing agent, 5 parts by weight of dibenzoyl peroxide crosslinking agent, 10 parts by weight of carboxyl-terminated polybutadiene toughening agent, 12 parts by weight of silica filler, and 8 parts by weight of ethanol; S2.2, add silicone rubber and silica filler into a stirrer, and stir at 800 rpm for 15 min at room temperature until uniformly dispersed to obtain a premix; S2.3, add bisphenol F epoxy resin to the premix, stir at room temperature, stirring speed of 600rpm, stirring time 15min, so that it is fully mixed; add modified maleic acid dihydrazide curing agent, continue stirring at room temperature at 400rpm speed for 15min, ensure that it is evenly distributed in the mixture; S2.4 Dissolve dibenzoyl peroxide crosslinker in ethanol, add to the mixture, then add carboxyl-terminated polybutadiene toughening agent, and continue stirring at room temperature at 400 rpm for 10 min; S2.5. Place the mixture in a vacuum degassing machine for degassing with a vacuum degree of -0.09 MPa and a degassing time of 30 min to remove air bubbles introduced during the mixing process; pour the degassing mixture into a mold to ensure uniform filling without bubbles; cure under normal pressure with an initial curing temperature of 70°C, a main curing temperature of 90°C, a post-curing temperature of 130°C, and a curing time of 12 h; S2.6. After curing is completed, the mold is taken out and placed in the air to cool to room temperature to obtain a cured cross-linked rubber with added epoxy resin.

[0026] The preparation method of the modified maleic acid dihydrazide curing agent is as follows: S1.1, weigh the following components in parts by weight respectively: 55 parts by weight of maleic acid dihydrazide curing agent, 33 parts by weight of styryl acetone, 4 parts by weight of potassium tert-butoxide, and 15 parts by weight of ethanol; S1.2, dissolving maleic acid dihydrazide curing agent and potassium tert-butoxide in ethanol, stirring with a stirrer at a speed of 300 rpm for 30 minutes to fully dissolve them; dripping styryl acetone at a rate of 6 drops / minute, using an ice-water mixture to maintain the temperature at 4°C, to obtain a reaction mixture; S1.3, after the addition was completed, the reaction mixture was warmed to room temperature, then heated to 60°C, stirred at 600 rpm, and nitrogen was introduced at a rate of 100 mL / min, and the reaction was continued for 12 h; S1.4. After the reaction is completed, the reaction mixture is cooled to room temperature to allow the product to crystallize and then filtered; it is washed with deionized water to remove the residual catalyst and other impurities; after washing, it is freeze-dried at a drying temperature of -40°C and a drying time of 6 hours to obtain a modified maleic acid dihydrazide curing agent.

[0027] Embodiment 3: Cured cross-linked rubber with epoxy resin added and preparation method thereof, comprising the following steps: S2.1, weigh the following components in parts by weight respectively: 60 parts by weight of bisphenol F epoxy resin, 30 parts by weight of silicone rubber, 10 parts by weight of modified maleic acid dihydrazide curing agent, 5 parts by weight of dibenzoyl peroxide crosslinking agent, 10 parts by weight of carboxyl-terminated polybutadiene toughening agent, 12 parts by weight of silica filler, and 8 parts by weight of ethanol; S2.2, add silicone rubber and silica filler into a stirrer, and stir at 800 rpm for 15 min at room temperature until uniformly dispersed to obtain a premix; S2.3, add bisphenol F epoxy resin to the premix, stir at room temperature, stirring speed of 600rpm, stirring time 15min, so that it is fully mixed; add modified maleic acid dihydrazide curing agent, continue stirring at room temperature at 400rpm speed for 15min, ensure that it is evenly distributed in the mixture; S2.4 Dissolve dibenzoyl peroxide crosslinker in ethanol, add to the mixture, then add carboxyl-terminated polybutadiene toughening agent, and continue stirring at room temperature at 400 rpm for 10 min; S2.5. Place the mixture in a vacuum degassing machine for degassing with a vacuum degree of -0.09 MPa and a degassing time of 30 min to remove air bubbles introduced during the mixing process; pour the degassing mixture into a mold to ensure uniform filling without bubbles; cure under normal pressure with an initial curing temperature of 70°C, a main curing temperature of 90°C, a post-curing temperature of 130°C, and a curing time of 12 h; S2.6. After curing is completed, the mold is taken out and placed in the air to cool to room temperature to obtain a cured cross-linked rubber with added epoxy resin.

[0028] The preparation method of the modified maleic acid dihydrazide curing agent is as follows: S1.1, weigh the following components in parts by weight respectively: 55 parts by weight of maleic acid dihydrazide curing agent, 36 parts by weight of styryl acetone, 4 parts by weight of potassium tert-butoxide, and 15 parts by weight of ethanol; S1.2, dissolving maleic acid dihydrazide curing agent and potassium tert-butoxide in ethanol, stirring with a stirrer at a speed of 300 rpm for 30 minutes to fully dissolve them; dripping styryl acetone at a rate of 6 drops / minute, using an ice-water mixture to maintain the temperature at 4°C, to obtain a reaction mixture; S1.3, after the addition was completed, the reaction mixture was warmed to room temperature, then heated to 60°C, stirred at 600 rpm, and nitrogen was introduced at a rate of 100 mL / min, and the reaction was continued for 12 h; S1.4. After the reaction is completed, the reaction mixture is cooled to room temperature to allow the product to crystallize and then filtered; it is washed with deionized water to remove the residual catalyst and other impurities; after washing, it is freeze-dried at a drying temperature of -40°C and a drying time of 6 hours to obtain a modified maleic acid dihydrazide curing agent.

[0029] Embodiment 4: Cured cross-linked rubber with epoxy resin added and preparation method thereof, comprising the following steps: S2.1, weigh the following components in parts by weight respectively: 60 parts by weight of bisphenol F epoxy resin, 30 parts by weight of silicone rubber, 10 parts by weight of modified maleic acid dihydrazide curing agent, 5 parts by weight of dibenzoyl peroxide crosslinking agent, 10 parts by weight of carboxyl-terminated polybutadiene toughening agent, 12 parts by weight of silica filler, and 8 parts by weight of ethanol; S2.2, add silicone rubber and silica filler into a stirrer, and stir at 800 rpm for 15 min at room temperature until uniformly dispersed to obtain a premix; S2.3, add bisphenol F epoxy resin to the premix, stir at room temperature, stirring speed of 600rpm, stirring time 15min, so that it is fully mixed; add modified maleic acid dihydrazide curing agent, continue stirring at room temperature at 400rpm speed for 15min, ensure that it is evenly distributed in the mixture; S2.4 Dissolve dibenzoyl peroxide crosslinker in ethanol, add to the mixture, then add carboxyl-terminated polybutadiene toughening agent, and continue stirring at room temperature at 400 rpm for 10 min; S2.5. Place the mixture in a vacuum degassing machine for degassing with a vacuum degree of -0.09 MPa and a degassing time of 30 min to remove air bubbles introduced during the mixing process; pour the degassing mixture into a mold to ensure uniform filling without bubbles; cure under normal pressure with an initial curing temperature of 70°C, a main curing temperature of 90°C, a post-curing temperature of 130°C, and a curing time of 12 h; S2.6. After curing is completed, the mold is taken out and placed in the air to cool to room temperature to obtain a cured cross-linked rubber with added epoxy resin.

[0030] The preparation method of the modified maleic acid dihydrazide curing agent is as follows: S1.1, weigh the following components in parts by weight respectively: 55 parts by weight of maleic acid dihydrazide curing agent, 39 parts by weight of styryl acetone, 4 parts by weight of potassium tert-butoxide, and 15 parts by weight of ethanol; S1.2, dissolving maleic acid dihydrazide curing agent and potassium tert-butoxide in ethanol, stirring with a stirrer at a speed of 300 rpm for 30 minutes to fully dissolve them; dripping styryl acetone at a rate of 6 drops / minute, using an ice-water mixture to maintain the temperature at 4°C, to obtain a reaction mixture; S1.3, after the addition was completed, the reaction mixture was warmed to room temperature, then heated to 60°C, stirred at 600 rpm, and nitrogen was introduced at a rate of 100 mL / min, and the reaction was continued for 12 h; S1.4. After the reaction is completed, the reaction mixture is cooled to room temperature to allow the product to crystallize and then filtered; it is washed with deionized water to remove the residual catalyst and other impurities; after washing, it is freeze-dried at a drying temperature of -40°C and a drying time of 6 hours to obtain a modified maleic acid dihydrazide curing agent.

[0031] Embodiment 5: Cured cross-linked rubber with epoxy resin added and preparation method thereof, comprising the following steps: S2.1, weigh the following components in parts by weight respectively: 60 parts by weight of bisphenol F epoxy resin, 30 parts by weight of silicone rubber, 8 parts by weight of modified maleic acid dihydrazide curing agent, 5 parts by weight of dibenzoyl peroxide crosslinking agent, 10 parts by weight of carboxyl-terminated polybutadiene toughening agent, 12 parts by weight of silica filler, and 8 parts by weight of ethanol; S2.2, add silicone rubber and silica filler into a stirrer, and stir at 800 rpm for 15 min at room temperature until uniformly dispersed to obtain a premix; S2.3, add bisphenol F epoxy resin to the premix, stir at room temperature, stirring speed of 600rpm, stirring time 15min, so that it is fully mixed; add modified maleic acid dihydrazide curing agent, continue stirring at room temperature at 400rpm speed for 15min, ensure that it is evenly distributed in the mixture; S2.4 Dissolve dibenzoyl peroxide crosslinker in ethanol, add to the mixture, then add carboxyl-terminated polybutadiene toughening agent, and continue stirring at room temperature at 400 rpm for 10 min; S2.5. Place the mixture in a vacuum degassing machine for degassing with a vacuum degree of -0.09 MPa and a degassing time of 30 min to remove air bubbles introduced during the mixing process; pour the degassing mixture into a mold to ensure uniform filling without bubbles; cure under normal pressure with an initial curing temperature of 70°C, a main curing temperature of 90°C, a post-curing temperature of 130°C, and a curing time of 12 h; S2.6. After curing is completed, the mold is taken out and placed in the air to cool to room temperature to obtain a cured cross-linked rubber with added epoxy resin.

[0032] The preparation method of the modified maleic acid dihydrazide curing agent is as follows: S1.1, weigh the following components in parts by weight respectively: 55 parts by weight of maleic acid dihydrazide curing agent, 36 parts by weight of styryl acetone, 2 parts by weight of potassium tert-butoxide, and 10 parts by weight of ethanol; S1.2, dissolving maleic acid dihydrazide curing agent and potassium tert-butoxide in ethanol, stirring with a stirrer at a speed of 300 rpm for 30 minutes to fully dissolve them; dripping styryl acetone at a rate of 6 drops / minute, using an ice-water mixture to maintain the temperature at 4°C, to obtain a reaction mixture; S1.3, after the addition was completed, the reaction mixture was warmed to room temperature, then heated to 60°C, stirred at 600 rpm, and nitrogen was introduced at a rate of 100 mL / min, and the reaction was continued for 12 h; S1.4. After the reaction is completed, the reaction mixture is cooled to room temperature to allow the product to crystallize and then filtered; it is washed with deionized water to remove the residual catalyst and other impurities; after washing, it is freeze-dried at a drying temperature of -40°C and a drying time of 6 hours to obtain a modified maleic acid dihydrazide curing agent.

[0033] Embodiment 6: Cured cross-linked rubber with epoxy resin added and preparation method thereof, comprising the following steps: S2.1, weigh the following components in parts by weight respectively: 50 parts by weight of bisphenol F epoxy resin, 20 parts by weight of silicone rubber, 10 parts by weight of modified maleic acid dihydrazide curing agent, 2 parts by weight of dibenzoyl peroxide crosslinking agent, 5 parts by weight of carboxyl-terminated polybutadiene toughening agent, 5 parts by weight of silica filler, and 5 parts by weight of ethanol; S2.2, add silicone rubber and silica filler into a stirrer, and stir at 800 rpm for 15 min at room temperature until uniformly dispersed to obtain a premix; S2.3, add bisphenol F epoxy resin to the premix, stir at room temperature, stirring speed of 600rpm, stirring time 15min, so that it is fully mixed; add modified maleic acid dihydrazide curing agent, continue stirring at room temperature at 400rpm speed for 15min, ensure that it is evenly distributed in the mixture; S2.4 Dissolve dibenzoyl peroxide crosslinker in ethanol, add to the mixture, then add carboxyl-terminated polybutadiene toughening agent, and continue stirring at room temperature at 400 rpm for 10 min; S2.5. Place the mixture in a vacuum degassing machine for degassing with a vacuum degree of -0.09 MPa and a degassing time of 30 min to remove air bubbles introduced during the mixing process; pour the degassing mixture into a mold to ensure uniform filling without bubbles; cure under normal pressure with an initial curing temperature of 70°C, a main curing temperature of 90°C, a post-curing temperature of 130°C, and a curing time of 12 h; S2.6. After curing is completed, the mold is taken out and placed in the air to cool to room temperature to obtain a cured cross-linked rubber with added epoxy resin.

[0034] The preparation method of the modified maleic acid dihydrazide curing agent is as follows: S1.1, weigh the following components in parts by weight respectively: 55 parts by weight of maleic acid dihydrazide curing agent, 36 parts by weight of styryl acetone, 4 parts by weight of potassium tert-butoxide, and 15 parts by weight of ethanol; S1.2, dissolving maleic acid dihydrazide curing agent and potassium tert-butoxide in ethanol, stirring with a stirrer at a speed of 300 rpm for 30 minutes to fully dissolve them; dripping styryl acetone at a rate of 6 drops / minute, using an ice-water mixture to maintain the temperature at 4°C, to obtain a reaction mixture; S1.3, after the addition was completed, the reaction mixture was warmed to room temperature, then heated to 60°C, stirred at 600 rpm, and nitrogen was introduced at a rate of 100 mL / min, and the reaction was continued for 12 h; S1.4. After the reaction is completed, the reaction mixture is cooled to room temperature to allow the product to crystallize and then filtered; it is washed with deionized water to remove the residual catalyst and other impurities; after washing, it is freeze-dried at a drying temperature of -40°C and a drying time of 6 hours to obtain a modified maleic acid dihydrazide curing agent.

[0035] Embodiment 7: Cured cross-linked rubber with epoxy resin added and preparation method thereof, comprising the following steps: S2.1, weigh the following components in parts by weight respectively: 60 parts by weight of bisphenol F epoxy resin, 30 parts by weight of silicone rubber, 13 parts by weight of modified maleic acid dihydrazide curing agent, 5 parts by weight of dibenzoyl peroxide crosslinking agent, 10 parts by weight of carboxyl-terminated polybutadiene toughening agent, 12 parts by weight of silica filler, and 8 parts by weight of ethanol; S2.2, add silicone rubber and silica filler into a stirrer, and stir at 800 rpm for 15 min at room temperature until uniformly dispersed to obtain a premix; S2.3, add bisphenol F epoxy resin to the premix, stir at room temperature, stirring speed of 600rpm, stirring time 15min, so that it is fully mixed; add modified maleic acid dihydrazide curing agent, continue stirring at room temperature at 400rpm speed for 15min, ensure that it is evenly distributed in the mixture; S2.4 Dissolve dibenzoyl peroxide crosslinker in ethanol, add to the mixture, then add carboxyl-terminated polybutadiene toughening agent, and continue stirring at room temperature at 400 rpm for 10 min; S2.5. Place the mixture in a vacuum degassing machine for degassing with a vacuum degree of -0.09 MPa and a degassing time of 30 min to remove air bubbles introduced during the mixing process; pour the degassing mixture into a mold to ensure uniform filling without bubbles; cure under normal pressure with an initial curing temperature of 70°C, a main curing temperature of 90°C, a post-curing temperature of 130°C, and a curing time of 12 h; S2.6. After curing is completed, the mold is taken out and placed in the air to cool to room temperature to obtain a cured cross-linked rubber with added epoxy resin.

[0036] The preparation method of the modified maleic acid dihydrazide curing agent is as follows: S1.1, weigh the following components in parts by weight respectively: 55 parts by weight of maleic acid dihydrazide curing agent, 36 parts by weight of styryl acetone, 4 parts by weight of potassium tert-butoxide, and 15 parts by weight of ethanol; S1.2, dissolving maleic acid dihydrazide curing agent and potassium tert-butoxide in ethanol, stirring with a stirrer at a speed of 300 rpm for 30 minutes to fully dissolve them; dripping styryl acetone at a rate of 6 drops / minute, using an ice-water mixture to maintain the temperature at 4°C, to obtain a reaction mixture; S1.3, after the addition was completed, the reaction mixture was warmed to room temperature, then heated to 60°C, stirred at 600 rpm, and nitrogen was introduced at a rate of 100 mL / min, and the reaction was continued for 12 h; S1.4. After the reaction is completed, the reaction mixture is cooled to room temperature to allow the product to crystallize and then filtered; it is washed with deionized water to remove the residual catalyst and other impurities; after washing, it is freeze-dried at a drying temperature of -40°C and a drying time of 6 hours to obtain a modified maleic acid dihydrazide curing agent.

[0037] The method of Example 7 was adopted, using unmodified maleic acid dihydrazide curing agent.

[0038] The method of Example 7 was used to remove the alkaline catalyst.

[0039] The method of Example 7 was adopted, and the modified maleic acid dihydrazide curing agent was replaced by phthalic anhydride, and phthalic anhydride was selected as the curing agent.

[0040] The present invention discloses a cross-linked rubber with epoxy resin added and prepared by using a modified maleic acid dihydrazide curing agent and a preparation method thereof, wherein the performance index inspection items and inspection standards of the cross-linked rubber with epoxy resin added are as follows: The tear strength of rubber is measured with reference to the standard ISO 34-1-2015. The maximum resistance to tear propagation of rubber is measured by a standard tensile testing machine. Higher tear strength indicates that the material has better tear resistance and brittleness resistance.

[0041] The maximum stress that the rubber can withstand until it breaks is measured using a standard tensile testing machine, reflecting the rubber's ability to resist tensile damage. When the rubber breaks, the elongation of the specimen is measured in proportion to its original length, usually expressed as a percentage. A high elongation indicates that the rubber can withstand a larger deformation before breaking, i.e., it has better flexibility and ductility.

[0042] According to the above standards, the cured cross-linked rubbers prepared in Examples 1-7 and Comparative Examples 1-3 with epoxy resin added were tested, and the obtained data are shown in Table 1: Table 1 Performance data of the cured cross-linked rubber of Examples 1-7 and Comparative Examples 1-3

[0043] It can be seen from Examples 1-4 that when the mass ratio of α,β-unsaturated ketone compounds to maleic acid dihydrazide in the modified maleic acid dihydrazide curing agent gradually increases, the tear strength and elongation of the rubber gradually increase, but when the mass ratio of α,β-unsaturated ketone compounds to maleic acid dihydrazide reaches a certain value, the tear strength and elongation of the rubber significantly decrease. It can be seen that with the increase of the mass ratio of α,β-unsaturated ketone compounds, the tear strength and elongation of the rubber are improved, but excessive increase may reduce the tear strength and elongation of the rubber; Specifically, the increase in the mass ratio of α,β-unsaturated ketone compounds to maleic acid dihydrazide makes the cross-linking reaction in the system more complete. Maleic acid dihydrazide, as a curing agent, undergoes a cross-linking reaction with the rubber molecular chain and α,β-unsaturated ketone compounds to form a three-dimensional network structure. As the content of α,β-unsaturated ketone compounds increases, more active sites participate in the cross-linking reaction, and the number of cross-linking points increases, thereby increasing the cross-linking density of the rubber. α,β-unsaturated ketone compounds usually contain polar groups, such as carbonyl groups, which produce strong intermolecular forces such as hydrogen bonds and dipole-dipole interactions, which make the rubber molecular chains more tightly bonded, improve the cohesion of the rubber, and further enhance the tear strength.

[0044] There may be a π-π conjugation effect between the double bonds in α,β-unsaturated ketone compounds and the double bonds or conjugated structures such as benzene rings in the rubber molecular chain. This conjugation effect can enhance the interaction between the molecular chains, making it less likely for the rubber molecular chains to slip relative to each other when subjected to force, thereby improving the mechanical properties of the rubber, including tear strength and elongation. A suitable mass ratio of α,β-unsaturated ketone compounds to maleic acid dihydrazide can improve the compatibility between rubber and other additives or fillers. When the compatibility is good, the components can be evenly dispersed in the rubber matrix to form a stable phase structure. This uniform phase structure is conducive to the uniform distribution of stress in the rubber and avoids stress concentration, thereby improving the tear strength and elongation of the rubber.

[0045] Further, by comparing Example 5, Example 6 and Example 7, it can be seen that when other components remain unchanged, only when the proportion of modified maleic acid dihydrazide curing agent gradually increases, the tear strength and elongation of the rubber are significantly improved. It can be seen that the increase in the content of modified maleic acid dihydrazide curing agent provides more cross-linking sites for the rubber molecular chains. During the vulcanization process, these sites react chemically with the rubber molecules to form a denser cross-linked network structure, making the connection between the rubber molecular chains tighter, thereby increasing the cross-linking density of the rubber, enhancing the cohesion of the rubber, and helping to improve the tear strength; sufficient modified maleic acid dihydrazide curing agent can ensure that the vulcanization reaction of the rubber is more sufficient, so that the rubber molecular chains are completely cross-linked, thereby exerting the best mechanical properties. If the curing agent is insufficient, the rubber may have incompletely cross-linked molecular chains, and these uncross-linked parts will reduce the strength and stability of the rubber; and when the proportion of the curing agent increases and reaches an appropriate amount, the rubber can be completely cured, and the properties such as tear strength and elongation are significantly improved.

[0046] By comparing Example 7 with Comparative Example 1, it can be seen that when unmodified maleic acid dihydrazide curing agent is used, the tear strength and elongation of the rubber are significantly reduced.

[0047] Taking Example 7 as the best example and combining it with Comparative Example 2, it can be seen that in the preparation method of the modified maleic acid dihydrazide curing agent, when the alkali catalyst is removed, the tear strength and elongation of the rubber are significantly reduced; Alkaline catalysts can promote the Michael addition reaction between maleic acid dihydrazide and α, β-unsaturated ketone compounds. In the absence of alkaline catalysts, the departure of active hydrogen in maleic acid dihydrazide molecules becomes difficult, and the process of forming nucleophilic reagents is inhibited, which greatly reduces the reactivity with α, β-unsaturated ketone compounds. Due to the reduced reactivity, maleic acid dihydrazide and α, β-unsaturated ketone compounds cannot fully react, and the modification degree of the curing agent is insufficient. When used for rubber curing, this insufficiently modified curing agent cannot effectively form a complete cross-linking network with the rubber molecules, resulting in a significant reduction in tear strength and elongation.

[0048] Example 7 is the best example, and combined with Comparative Example 3, it can be seen that when the modified maleic acid dihydrazide curing agent is replaced by phthalic anhydride, the tear strength and elongation of the rubber are significantly reduced; During the cross-linking process, phthalic anhydride may severely restrict the activity space of the rubber molecular chain. When the rubber is stretched by external force, the molecular chain is difficult to stretch freely, so the elongation will be significantly reduced; when subjected to tearing force, due to the high rigidity and poor flexibility of the cross-linking network, the stress caused by tearing cannot be well dispersed, and stress concentration is likely to occur locally, resulting in reduced tear strength; phthalic anhydride is prone to local aggregation during the curing process, resulting in an uneven cross-linking network. When subjected to external force, this uneven structure is likely to become a weak point, and it is more likely to be damaged from these weak areas under the action of tearing force, thereby reducing the tear strength; at the same time, uneven cross-linking will also limit the overall extension of the rubber molecular chain, resulting in a decrease in elongation.

[0049] The above shows and describes the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited by the above embodiments. The above embodiments and descriptions are only preferred examples of the present invention and are not intended to limit the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, which fall within the scope of the present invention. The scope of protection of the present invention is defined by the attached claims and their equivalents.

Claims

1. A cross-linked rubber containing epoxy resin, characterized in that: The invention comprises the following components: 50-70 parts by weight of epoxy resin, 20-40 parts by weight of silicone rubber, 5-15 parts by weight of modified maleic acid dihydrazide curing agent, 2-8 parts by weight of dibenzoyl peroxide crosslinking agent, 5-15 parts by weight of carboxyl-terminated polybutadiene toughening agent, 5-20 parts by weight of silica filler and 5-10 parts by weight of ethanol; The modified maleic acid dihydrazide curing agent is prepared by Michael addition reaction of maleic acid dihydrazide and α,β-unsaturated ketone compound under alkaline catalyst; the α,β-unsaturated ketone compound is any one of methyl vinyl ketone and styryl acetone.

2. The cured cross-linked rubber with epoxy resin added according to claim 1, characterized in that: The preparation method of the modified maleic acid dihydrazide curing agent is as follows: S1.

1. Weigh the following components in parts by weight respectively: 50-60 parts by weight of maleic acid dihydrazide curing agent, 30-40 parts by weight of α,β-unsaturated ketone compound, 2-5 parts by weight of base catalyst, and 10-20 parts by weight of ethanol; S1.2, dissolving the maleic acid dihydrazide curing agent and the alkaline catalyst in ethanol, stirring to fully dissolve; dripping the α,β-unsaturated ketone compound at a rate of 5-10 drops / minute, using an ice-water mixture to maintain the temperature at 0-5°C, to obtain a reaction mixture; S1.3, after the addition is completed, the reaction mixture is heated to room temperature, then heated to 40-60 ° C, stirred at a speed of 600-800 rpm, and nitrogen is introduced at a rate of 80-100 mL / min, and the reaction is continued for 9-12 hours; S1.

4. After the reaction is completed, the reaction mixture is cooled to room temperature to allow the product to crystallize and then filtered; it is washed with deionized water to remove the residual catalyst and other impurities; after washing, it is freeze-dried to obtain a modified maleic acid dihydrazide curing agent.

3. The cured cross-linked rubber with epoxy resin added according to claim 2, characterized in that: The base catalyst is any one of sodium ethoxide or potassium tert-butoxide.

4. The cured cross-linked rubber with epoxy resin added according to claim 2, characterized in that: In S1.2, stirring is performed by a stirrer at a speed of 300-400 rpm and a stirring time of 15-30 min.

5. The cured cross-linked rubber with epoxy resin added according to claim 2, characterized in that: In the above-mentioned S1.5, the drying temperature of freeze drying is -40 to -50°C, and the drying time is 4 to 6 hours.

6. A method for preparing a curable cross-linked rubber with epoxy resin added, which is used to prepare the curable cross-linked rubber with epoxy resin added as claimed in any one of claims 1 to 5, characterized in that: The preparation method of the cured cross-linked rubber with added epoxy resin is as follows: S2.1, weigh the following components in parts by weight respectively: 50-70 parts by weight of epoxy resin, 20-40 parts by weight of silicone rubber, 5-15 parts by weight of modified maleic acid dihydrazide curing agent, 2-8 parts by weight of dibenzoyl peroxide crosslinking agent, 5-15 parts by weight of carboxyl-terminated polybutadiene toughening agent, 5-20 parts by weight of silica filler, and 5-10 parts by weight of ethanol; S2.2, add silicone rubber and silica filler into a stirrer, stir at 600-800 rpm for 10-15 min at room temperature until uniformly dispersed to obtain a premix; S2.3, add epoxy resin to the premix, stir at room temperature to make it fully mixed; add modified maleic acid dihydrazide curing agent, continue stirring at room temperature at a speed of 400-500rpm for 15-20min to ensure that it is evenly distributed in the mixture; S2.4 Dissolve dibenzoyl peroxide crosslinker in ethanol, add to the mixture, then add carboxyl-terminated polybutadiene toughening agent, and continue stirring at room temperature at a speed of 400-500 rpm for 5-10 minutes; S2.

5. Pour the deaerated mixture into the mold, ensuring that it is evenly filled and free of bubbles; cure it under normal pressure for 6-12 hours; S2.

6. After curing is completed, the mold is taken out and placed in the air to cool to room temperature to obtain a cured cross-linked rubber with added epoxy resin.

7. The method for preparing a cured cross-linked rubber with epoxy resin added according to claim 6, characterized in that: The epoxy resin is any one of bisphenol F epoxy resin and polyethylene glycol diglycidyl ether.

8. The method for preparing a cured cross-linked rubber with epoxy resin added according to claim 6, characterized in that: In S2.3, the stirring speed of adding the epoxy resin into the premix is ​​600-800 rpm, and the stirring time of adding the epoxy resin into the premix is ​​10-15 min.

9. The method for preparing a cured cross-linked rubber with epoxy resin added according to claim 6, characterized in that: In S2.5, the degassing treatment is to place the mixture in a vacuum degassing machine with a vacuum degree of -0.08 to -0.1 MPa and a degassing time of 10 to 30 minutes to remove air bubbles introduced during the mixing process.

10. The method for preparing a curing cross-linking rubber with epoxy resin added according to claim 6, characterized in that: In the S2.5, the initial curing temperature is 60-80°C, the main curing temperature is 80-100°C, and the post-curing temperature is 120-150°C.

Images