A ternary ethylene propylene rubber composite material and a preparation method thereof

Abstract

The application belongs to the technical field of rubber materials, and particularly relates to a kind of EPDM composite material and its preparation method.The EPDM composite material comprises the following components by weight fraction: 100 parts of EPDM, 8-15 parts of polyurethane prepolymer, 10-15 parts of reinforcing agent, 50-80 parts of white carbon black, 2-5 parts of dispersing agent, 0.8-1.2 parts of vulcanization accelerator and 2-3 parts of vulcanizing agent.The EPDM composite material has excellent mechanical properties and adhesive strength, and also has good flame retardant performance.

Description

Technical Field

[0001] The invention belongs to the technical field of rubber materials, and in particular relates to an EPDM rubber composite material and a preparation method thereof. Background Art

[0002] Rubber materials are a critical strategic resource due to their unique high elasticity, allowing them to maintain their original shape even after significant deformation. Ethylene propylene diene monomer (EPDM), a terpolymer of ethylene, propylene, and a non-conjugated diene, has a saturated hydrocarbon backbone, making it a non-crystalline rubber with poor self-reinforcement. Since its industrial production began in the 1960s, it has been widely used in automotive sealing strips, building waterproofing materials, wire and cable insulation, and household products due to its excellent weather resistance, ozone resistance, chemical corrosion resistance, and electrical insulation properties. However, traditional EPDM rubber also has inherent flaws: its molecular chain is highly flexible but has low polarity, and at high ethylene content, it exhibits a certain degree of crystallization, resulting in insufficient mechanical strength and poor adhesion to extreme substrates such as metals and plastics. This ultimately impairs the product's overall performance, making it difficult to meet the comprehensive material performance requirements of high-end applications.

[0003] In order to solve the above problems, domestic and foreign research has mostly optimized performance through filling modification, blending and compounding, and even dynamic vulcanization. Early research focused on adding reinforcing fillers such as carbon black and white carbon black. Although they can improve tensile strength, they will deteriorate the processing performance of the material. In recent years, the application of nanofillers such as graphene, carbon nanotubes and montmorillonite has become a hot topic, but the high surface energy of nanomaterials can easily lead to agglomeration, poor dispersion and high cost. Most importantly, traditional modification technologies often focus on a certain property (such as only enhancing mechanics or only improving flame retardancy), and cannot take into account the comprehensive performance of the material.

[0004] Therefore, in response to the above problems, it is urgent to develop rubber composites with high performance to meet the needs of industrial production and application. Summary of the Invention

[0005] In order to overcome the deficiencies of the prior art, one of the objectives of the present invention is to provide an EPDM rubber composite material.

[0006] One of the purposes of the present invention is achieved by the following technical solution:

[0007] An EPDM rubber composite material comprises the following components, measured in parts by weight: 100 parts of EPDM rubber, 8-15 parts of polyurethane prepolymer, 10-15 parts of reinforcing agent, 50-80 parts of white carbon black, 2-5 parts of dispersant, 0.8-1.2 parts of vulcanization accelerator, and 2-3 parts of vulcanizing agent.

[0008] Further, the mass ratio of the polyurethane prepolymer, the reinforcing agent and the white carbon black is 1: (1-1.5): (5-6.5).

[0009] Further, the preparation process of the reinforcing agent comprises the following steps:

[0010] (1) glycerol, alkali metal carbonate and 6-bromo-n-hexanal are added into solvent A for reaction, and after the reaction is completed, intermediate 1 is obtained by purification; the structural formula of the intermediate 1 is ;

[0011] (2) intermediate 1, pentamethyl aniline and glacial acetic acid are added into solvent B, and after stirring and mixing, sodium cyanoborohydride is added for reaction; after the reaction liquid is concentrated and extracted, the organic phase is combined, and then dried, filtered, concentrated and purified to obtain the reinforcing agent; the structure of the reinforcing agent is .

[0012] The reinforcing agent is based on glycerol as a matrix skeleton, and a long-chain aliphatic hydrocarbon group is introduced by flexible connection through ether bond (-O-), and the terminal is bonded to an aromatic ring structure benzene ring through an amino group (-NH2).

[0013] Further, in step (1), the molar ratio of the glycerol, the alkali metal carbonate and the 6-bromo-n-hexanal is 1: (6-7.5): (3-3.3), and the concentration of the glycerol in the solvent A is 0.1 mol / L.

[0014] Further, in step (1), the alkali metal carbonate is potassium carbonate or sodium carbonate, and the solvent A is N,N-dimethylformamide; the temperature of the reaction is 90-110℃, and the time is 12-16h.

[0015] Further, in step (1), after the reaction is completed, the following steps are specifically included: water is added to the reaction liquid until the solid precipitates.

[0016] Further, in step (2), the molar ratio of the intermediate 1, pentamethyl aniline, glacial acetic acid and sodium cyanoborohydride is 1: (3-3.5): (3-4): (6-7.5), and the concentration of the intermediate 1 in the solvent B is 0.2 mol / L; the time of the reaction is 16-24h; in step (2), the solvent B is methanol, and the solvent used for extraction is dichloromethane.

[0017] Further, the preparation steps of the polyurethane prepolymer are as follows: according to the weight fraction, 30 parts of polytetrahydrofuran ether glycol, 15-18 parts of triphenyl isocyanate phosphorothioate, 0.5-0.8 parts of triethylene diamine and 1-2 parts of glycerol are weighed, and then stirred and reacted under anhydrous system to obtain the polyurethane prepolymer.

[0018] Furthermore, the stirring reaction is carried out at a temperature of 90-100° C. for 18-24 hours.

[0019] A second object of the present invention is to provide a method for preparing the above-mentioned EPDM rubber composite material, which is easy to operate and feasible, and is convenient for industrial production.

[0020] The second object of the present invention is achieved by adopting the following technical solution:

[0021] The preparation method of the EPDM rubber composite material comprises the following steps:

[0022] a. According to the parts by weight, the EPDM rubber, reinforcing agent, polyurethane prepolymer, silica, and dispersant are uniformly mixed and then kneaded to obtain a rubber mix;

[0023] b. Adding a vulcanization accelerator and a vulcanizing agent to the rubber mix and mixing the mixture, then molding the mixture to obtain a preform, and vulcanizing the preform to obtain an EPDM rubber composite material.

[0024] Furthermore, the mixing temperature in step a is 125-135° C., and the mixing time is 12-15 min; the mixing temperature in step b is the same as that in step a, and the mixing time is 3-5 min; the vulcanization temperature is 170-180° C., and the time is 6-8 min.

[0025] Furthermore, the dispersant is sodium stearate or potassium stearate; the vulcanization accelerator is N-cyclohexyl-2-benzothiazolylsulfenamide or tetrabenzylthiuram disulfide; and the vulcanizing agent is sulfur or dicumyl peroxide.

[0026] Compared with the prior art, the present invention has the following beneficial effects:

[0027] 1. The present invention provides an EPDM rubber composite material. The material is prepared by compounding EPDM rubber, polyurethane prepolymer, reinforcing agent and other auxiliary materials. The composite material not only has high bonding strength and mechanical properties, but also has good flame retardant properties.

[0028] On the one hand, the appropriate amount of short chain branches contained in the reinforcing agent of the present invention can enhance the mobility of the molecular chain and improve its dispersion uniformity in the rubber matrix; the steric hindrance effect generated by the short chain branches effectively inhibits the excessive aggregation of macromolecules and forms a stable dispersed phase. This unique molecular architecture enables the reinforcing agent to exert an interfacial bridging effect while giving the composite material excellent processing fluidity, ultimately achieving a synergistic improvement in high cohesive energy, flame retardancy and mechanical strength. On the other hand, the fatty chain segments introduced into the reinforcing agent are physically entangled with the non-polar main chain of the EPDM rubber, and the aromatic groups in the reinforcing agent form π-π conjugation with the rigid benzene rings in the polyurethane prepolymer. At the same time, the polar sites of the ether bonds and amino groups undergo chemical cross-linking with active functional groups such as the isocyanate group (-NCO) of the polyurethane, constructing a multi-scale interfacial bonding mechanism and significantly improving the bonding strength and mechanical strength of the composite system.

[0029] 2. The present invention provides a method for preparing an EPDM rubber composite material, which is simple and feasible and can be easily industrialized for production. DETAILED DESCRIPTION

[0030] Below, in conjunction with specific embodiments, the present invention is further described. It should be noted that, under the premise of no conflict, the various embodiments described below or the various technical features can be arbitrarily combined to form new embodiments. Specific conditions not specified in the embodiments are carried out according to conventional conditions or conditions recommended by the manufacturer. Reagents or instruments used, unless otherwise specified, are conventional products obtained through commercial channels.

[0031] Example 1

[0032] An EPDM rubber composite material comprises the following components, measured in parts by weight: 100 parts of EPDM rubber, 12 parts of polyurethane prepolymer, 12 parts of reinforcing agent, 70 parts of white carbon black, 3 parts of sodium stearate, 1 part of N-cyclohexyl-2-benzothiazolyl sulfenamide, and 2.5 parts of sulfur.

[0033] The preparation process of the polyurethane prepolymer comprises the following steps: weighing 30 parts of polytetramethylene ether glycol, 16 parts of triphenyl isocyanate thiophosphate, 0.6 parts of triethylenediamine, and 1.5 parts of glycerol, by weight, adding the mixture into a reaction kettle, removing moisture from the reaction system under a negative pressure of 0.1 MPa for 10 minutes while stirring, then reacting at 95° C. for 20 hours, and cooling the reaction system to room temperature to obtain the polyurethane prepolymer.

[0034] The preparation process of the enhancer comprises the following steps:

[0035]

[0036] (1) Under nitrogen atmosphere, potassium carbonate (70 mmol), glycerol (10 mmol), and 6-bromohexanal (31 mmol) were added to 100 mL of N,N-dimethylformamide and stirred at 100°C for 14 h. The reaction solution was poured into 500 mL of water to precipitate a solid. After filtration, the filter cake was purified by silica gel column chromatography (eluent: 80% petroleum ether, 20% dichloromethane) to obtain intermediate 1 (yield 35.41%). The characterization results of intermediate 1 are as follows: 1 H NMR (C 21 H 38 H NMR (400 MHz, CDCl3) δ 9.65 (t, 3H), 3.75-3.73 (m, 1H), 3.53 (d, 4H), 3.40 (t, 6H), 2.43 (q, 6H), 1.59-1.49 (m,12H), 1.31-1.28 (m, 6H); the above results confirmed that the target product was obtained.

[0037] (2) Under nitrogen atmosphere, pentamethylaniline (65 mmol), glacial acetic acid (65 mmol) and intermediate 1 (20 mmol) were added to 100 mL of methanol, stirred evenly, and then sodium cyanoborohydride (140 mmol) was added. The reaction was allowed to react at room temperature for 20 h. The reaction was quenched with saturated sodium bicarbonate solution, and the mixture was concentrated to remove most of the methanol. The mixture was then extracted three times with dichloromethane. The organic phases were combined, dried over anhydrous sodium sulfate, filtered, concentrated, and purified by silica gel column chromatography (eluent: 95% by volume n-hexane, 5% by volume dichloromethane) to obtain the enhancer (yield 78.65%). The characterization results of the enhancer are as follows: 1 H NMR (C 54 H 89 N3O3, 400 MHz, CDCl3) δ6.36(s, 3H), 3.75-3.73 (m, 1H), 3.53(d, 4H), 3.40-3.35(m, 12H), 2.27(s, 9H),2.20(s, 18H), 2.14(s, 18H), 1.57-1.42 (m, 18H), 1.31-1.28 (m, 6H); the above results confirmed that the target product was obtained.

[0038] This embodiment also provides a method for preparing the above-mentioned EPDM rubber composite material, comprising the following steps:

[0039] a. According to the parts by weight, the EPDM rubber, reinforcing agent, polyurethane prepolymer, white carbon black, sodium stearate were uniformly mixed, put into an internal mixer, and mixed at 130 ℃ for 13min to obtain a rubber mix;

[0040] b. The rubber mix was transferred to an open mill, N-cyclohexyl-2-benzothiazolylsulfenamide and sulfur were added, mixed at 130°C for 4 minutes, and then molded into a preform. Finally, the preform was vulcanized at a vulcanization temperature of 172°C for 7 minutes to obtain an EPDM rubber composite material.

[0041] Example 2

[0042] An EPDM rubber composite material comprises the following components, measured in parts by weight: 100 parts of EPDM rubber, 8 parts of polyurethane prepolymer, 10 parts of reinforcing agent, 50 parts of white carbon black, 2 parts of potassium stearate, 0.8 parts of tetrabenzylthiuram disulfide, and 2 parts of dicumyl peroxide.

[0043] The preparation process of the polyurethane prepolymer comprises the following steps: weighing 30 parts of polytetramethylene ether glycol, 15 parts of triphenyl isocyanate thiophosphate, 0.5 parts of triethylenediamine, and 1 part of glycerol, by weight, adding the mixture into a reaction kettle, removing moisture from the reaction system under a negative pressure of 0.1 MPa for 10 minutes while stirring, then reacting at 90° C. for 24 hours, and cooling the reaction system to room temperature to obtain the polyurethane prepolymer.

[0044] The preparation process of the enhancer comprises the following steps:

[0045] (1) Under nitrogen atmosphere, potassium carbonate (60 mmol), glycerol (10 mmol), and 6-bromohexanal (30 mmol) were added to 100 mL of N,N-dimethylformamide and stirred at 90°C for 16 h. The reaction solution was poured into 500 mL of water to precipitate a solid. After filtration, the filter cake was purified by silica gel column chromatography (eluent: 80% by volume petroleum ether, 20% by volume dichloromethane) to obtain Intermediate 1 (yield 34.32%). The characterization results of Intermediate 1 were the same as those in Example 1.

[0046] (2) Under a nitrogen atmosphere, pentamethylaniline (60 mmol), glacial acetic acid (60 mmol), and intermediate 1 (20 mmol) were added to 100 mL of methanol, stirred evenly, and sodium cyanoborohydride (120 mmol) was added. The mixture was reacted at room temperature for 16 h. The reaction was quenched with a saturated sodium bicarbonate solution, and the mixture was concentrated to remove most of the methanol. The mixture was then extracted three times with dichloromethane. The organic phases were combined, dried over anhydrous sodium sulfate, filtered, concentrated, and purified by silica gel column chromatography (eluent: 95% by volume n-hexane, 5% by volume dichloromethane) to obtain an enhancer (yield 77.23%). The characterization results of the enhancer were the same as those in Example 1.

[0047] This embodiment also provides a method for preparing the above-mentioned EPDM rubber composite material, comprising the following steps:

[0048] a. According to the parts by weight, the EPDM rubber, reinforcing agent, polyurethane prepolymer, white carbon black, potassium stearate were uniformly mixed, put into an internal mixer, and mixed at 125 ℃ for 15min to obtain a rubber mix;

[0049] b. The rubber mix was transferred to an open mill, tetrabenzylthiuram disulfide and dicumyl peroxide were added, mixed at 125 ° C for 3 min, and then formed into a preform by compression molding. Finally, the preform was vulcanized at a vulcanization temperature of 170 ° C for 8 min to obtain an EPDM rubber composite material.

[0050] Example 3

[0051] An EPDM rubber composite material comprises the following components, measured in parts by weight: 100 parts of EPDM rubber, 15 parts of polyurethane prepolymer, 15 parts of reinforcing agent, 80 parts of white carbon black, 5 parts of sodium stearate, 1.2 parts of N-cyclohexyl-2-benzothiazolyl sulfenamide, and 3 parts of sulfur.

[0052] The preparation process of the polyurethane prepolymer comprises the following steps: weighing 30 parts of polytetramethylene ether glycol, 18 parts of triphenyl isocyanate thiophosphate, 0.8 parts of triethylenediamine, and 2 parts of glycerol by weight, adding the mixture into a reaction kettle, removing moisture from the reaction system under a negative pressure of 0.1 MPa for 10 minutes while stirring, then reacting at 100° C. for 18 hours, and cooling the reaction system to room temperature to obtain the polyurethane prepolymer.

[0053] The preparation process of the enhancer comprises the following steps:

[0054] (1) Under nitrogen atmosphere, sodium carbonate (75 mmol), glycerol (10 mmol), and 6-bromohexanal (33 mmol) were added to 100 mL of N,N-dimethylformamide and stirred at 110°C for 12 h. The reaction solution was poured into 500 mL of water to precipitate a solid. After filtration, the filter cake was purified by silica gel column chromatography (eluent: 80% by volume petroleum ether, 20% by volume dichloromethane) to obtain Intermediate 1 (yield 34.95%). The characterization results of Intermediate 1 were the same as those in Example 1.

[0055] (2) Under a nitrogen atmosphere, pentamethylaniline (70 mmol), glacial acetic acid (80 mmol), and intermediate 1 (20 mmol) were added to 100 mL of methanol, stirred evenly, and sodium cyanoborohydride (150 mmol) was added. The mixture was reacted at room temperature for 24 h. The reaction was quenched with a saturated sodium bicarbonate solution, and the mixture was concentrated to remove most of the methanol. The mixture was then extracted three times with dichloromethane. The organic phases were combined, dried over anhydrous sodium sulfate, filtered, concentrated, and purified by silica gel column chromatography (eluent: 95% by volume n-hexane, 5% by volume dichloromethane) to obtain an enhancer (yield 78.16%). The characterization results of the enhancer were the same as those in Example 1.

[0056] This embodiment also provides a method for preparing the above-mentioned EPDM rubber composite material, comprising the following steps:

[0057] a. According to the parts by weight, the EPDM rubber, reinforcing agent, polyurethane prepolymer, white carbon black, sodium stearate were uniformly mixed, put into an internal mixer, and mixed at 135 ℃ for 12min to obtain a rubber mix;

[0058] b. The rubber mix was transferred to an open mill, N-cyclohexyl-2-benzothiazolylsulfenamide and sulfur were added, mixed at 135°C for 5 minutes, and then molded into a preform. Finally, the preform was vulcanized at a vulcanization temperature of 175°C for 6 minutes to obtain an EPDM rubber composite material.

[0059] Comparative Example 1

[0060] This comparative example 1 is basically the same as Example 1, except that the enhancer is omitted and the other aspects are the same as Example 1.

[0061] Comparative Example 2

[0062] Comparative Example 2 is basically the same as Example 1, except that in the process of preparing the polyurethane prepolymer, triphenylisocyanate thiophosphate is replaced by hexamethylene diisocyanate, and the rest is consistent with Example 1.

[0063] Test Example 1

[0064] 1. The mechanical properties of composite materials were tested using an electronic universal testing machine. Samples were cut into dumbbell-shaped specimens using a cutter and tested according to the national standard GB / T 528-2009. The speed was 500.0 mm / min and the constant force attenuation rate was 40.0%.

[0065] 2. Tear strength is tested in accordance with GB / T 529-2008 using right-angle specimens.

[0066] 3. Test the bonding strength according to GB / T11211-2009 "Determination of bond strength between vulcanized rubber or thermoplastic rubber and metal";

[0067] 4. Shore A hardness is tested in accordance with GB / T 531.1-2008;

[0068] 5. Flame retardancy was tested using a limiting oxygen index tester in accordance with GB / T 10707-2008, "Rubber - Determination of Combustion Properties." The test environment was maintained at a temperature of 23±2°C and a humidity of 45%-75%. The results are shown in Table 1.

[0069] Table 1

[0070]

[0071] From the test results of Table 1, it can be seen that the tensile strength, elongation at break, adhesive strength, tear strength, etc. of the inventive examples 1-3 have been greatly improved compared with the comparative examples 1 and 2. The above results are attributed to the compounding use of the ethylene-propylene-diene rubber, polyurethane prepolymer, reinforcing agent and other auxiliary materials in the present application. The reinforcing agent has a unique molecular architecture, which endows the rubber composite material with excellent processing fluidity, realizes the synergistic improvement of high cohesive energy, flame retardant performance and mechanical strength. In addition, the reinforcing agent not only can physically entangle with the non-polar main chain of the ethylene-propylene-diene rubber, but also can form π-π conjugation with the rigid benzene ring in the polyurethane prepolymer, thus constructing a multi-scale interface bonding mechanism, thereby significantly improving the mechanical strength and adhesive strength of the composite system.

[0072] The materials of the inventive examples 1-3 have excellent flame retardant performance, and are significantly better than the comparative example 2. This is because the thiophosphoric acid triphenyl isocyanate is introduced into the polyurethane prepolymer, and the phosphorus element in this molecule decomposes to generate acidic substances such as phosphoric acid and metaphosphoric acid when heated. These acids catalyze the dehydration of the hydroxyl groups (-OH) in the rubber molecules, forming a dense carbonized layer, which can endow the rubber composite material with good flame retardant performance.

[0073] The above embodiments are only preferred embodiments of the present application, and cannot be used to limit the scope of protection of the present application. Any non-essential changes and substitutions made by those skilled in the art on the basis of the present application are within the scope of protection of the present application.

Claims

1. An EPDM rubber composite material, characterized in that: The composition comprises the following components by weight: 100 parts of EPDM rubber, 8-15 parts of polyurethane prepolymer, 10-15 parts of reinforcing agent, 50-80 parts of white carbon black, 2-5 parts of dispersant, 0.8-1.2 parts of vulcanization accelerator, and 2-3 parts of vulcanizing agent; The preparation process of the enhancer comprises the following steps: (1) Glycerol, alkali metal carbonate and 6-bromohexanal are added to solvent A for reaction. After the reaction is completed, intermediate 1 is obtained through purification. The structural formula of intermediate 1 is ; (2) Add intermediate 1, pentamethylaniline and glacial acetic acid to solvent B, stir and mix, then add sodium cyanoborohydride to react, concentrate the reaction solution, extract, combine the organic phases, and then dry, filter, concentrate and purify to obtain an enhancer; the structure of the enhancer is ; The preparation steps of the polyurethane prepolymer are as follows: 30 parts of polytetramethylene ether glycol, 15-18 parts of triphenyl isocyanate thiophosphate, 0.5-0.8 parts of triethylenediamine, and 1-2 parts of glycerol are weighed in parts by weight, and stirred in an anhydrous system for reaction to obtain the polyurethane prepolymer.

2. The EPDM rubber composite material according to claim 1, characterized in that: In step (1), the molar ratio of the glycerol, the alkali metal carbonate and 6-bromohexanal is 1: (6-7.5): (3-3.3), and the concentration of the glycerol in solvent A is 0.1 mol / L.

3. The EPDM rubber composite material according to claim 1, characterized in that: In step (1), the alkali metal carbonate is potassium carbonate or sodium carbonate, and the solvent A is N,N-dimethylformamide; the reaction temperature is 90-110° C., and the reaction time is 12-16 h.

4. The EPDM rubber composite material according to claim 1, characterized in that: In step (2), the molar ratio of the intermediate 1, pentamethylaniline, glacial acetic acid and sodium cyanoborohydride is 1:(3-3.5):(3-4):(6-7.5), the concentration of the intermediate 1 in solvent B is 0.2 mol / L; the reaction time is 16-24 h; the solvent B is methanol; and the solvent used for extraction is dichloromethane.

5. The EPDM rubber composite material according to claim 1, characterized in that: The stirring reaction temperature is 90-100°C and the time is 18-24 hours.

6. The method for preparing the EPDM rubber composite material according to any one of claims 1 to 5, wherein: The steps include: a. According to the parts by weight, the EPDM rubber, reinforcing agent, polyurethane prepolymer, silica, and dispersant are uniformly mixed and then kneaded to obtain a rubber mix; b. Adding a vulcanization accelerator and a vulcanizing agent to the rubber mix and mixing the mixture, then molding the mixture to obtain a preform, and vulcanizing the preform to obtain an EPDM rubber composite material.

7. The method for preparing the EPDM rubber composite material according to claim 6, characterized in that: The mixing temperature of step a is 125-135° C., and the mixing time is 12-15 min. The mixing temperature of step b is the same as that of step a, and the mixing time is 3-5 min. The vulcanization temperature is 170-180° C., and the time is 6-8 min.

8. The method for preparing the EPDM rubber composite material according to claim 6, characterized in that: The dispersant is sodium stearate or potassium stearate; the vulcanization accelerator is N-cyclohexyl-2-benzothiazolylsulfenamide or tetrabenzylthiuram disulfide; and the vulcanizing agent is sulfur or dicumyl peroxide.

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