Ethylene-propylene-diene monomer rubber composite material for automobile sealing strip and preparation process of ethylene-propylene-diene monomer rubber composite material

Abstract

The invention relates to the technical field of ethylene propylene diene monomer, and discloses an ethylene propylene diene monomer composite material for an automobile sealing strip and a preparation process of the ethylene propylene diene monomer composite material. The ethylene propylene diene monomer composite material comprises the following components in parts by weight: 55-75 parts of ethylene propylene diene monomer, 25-45 parts of ethylene-vinyl acetate copolymer, 2-8 parts of nano titanium dioxide, 0.4-1.5 parts of vinyl acetate polymer, 1-1.8 parts of vulcanizing agent and the like. A polyvinyl acetate molecular chain is grafted on the surface of the nano titanium dioxide, so that the nano titanium dioxide has good compatibility with the ethylene-vinyl acetate copolymer and the ethylene propylene diene monomer, can be uniformly dispersed in the composite material, and has a better reinforcing effect on the material; the prepared EPDM rubber composite material has excellent hardness, tensile strength, elongation at break and tear strength, and can be better applied to the automobile industry fields such as sealing strips.

Description

Technical Field

[0001] This invention relates to the field of EPDM rubber technology, specifically to an EPDM rubber composite material for automotive sealing strips and its preparation process. Background Technology

[0002] Ethylene propylene diene monomer (EPDM) rubber exhibits high elasticity, excellent aging and weather resistance, and good corrosion resistance, making it widely used in the automotive industry, wire and cable, and construction. However, EPDM rubber suffers from relatively low tensile strength and tear strength. To improve its mechanical strength, fillers such as elastomers and inorganic nanoparticles are added. Ethylene-vinyl acetate copolymer (EVA) is a high-performance elastomer material with good compatibility with EPDM rubber, resulting in composite materials with even better mechanical properties.

[0003] Adding inorganic nanomaterials to EPDM rubber can further improve the mechanical strength and heat resistance of the composite material. Nano-titanium dioxide is inexpensive and readily available, possesses high mechanical strength, and exhibits excellent UV resistance, making it widely used in polymer materials such as EPDM rubber and ethylene-vinyl acetate copolymers. Solving the agglomeration problem of nano-titanium dioxide and improving its compatibility with polymers are key research challenges. Summary of the Invention

[0004] This invention solves the problems of poor dispersion of nano-titanium dioxide in ethylene propylene diene monomer (EPDM) rubber and ethylene-vinyl acetate copolymer composites, and the poor mechanical properties of the composites.

[0005] The technical solution provided by this invention is: a EPDM rubber composite material and its preparation process, comprising 55-75 parts by weight of EPDM rubber, 25-45 parts by weight of ethylene-vinyl acetate copolymer, 2-8 parts by weight of nano-titanium dioxide, 0.4-1.5 parts by weight of vinyl acetate polymer, 2-2.8 parts by weight of antioxidant, 1-1.8 parts by weight of vulcanizing agent, 1.4-2 parts by weight of vulcanizing aid, 1-1.5 parts by weight of accelerator, and 4-7 parts by weight of additives.

[0006] The preparation process includes:

[0007] (1) Add 3-(3,4-dihydroxyphenyl) vinyl acrylate and emulsifier to water, stir, add initiator under nitrogen atmosphere, heat to reaction temperature, stir reaction, filter, wash with water and ethanol in turn, dry to obtain vinyl acetate polymer.

[0008] (2) Add nano-titanium dioxide to toluene, disperse ultrasonically, then add vinyl acetate polymer, heat and stir, remove toluene by vacuum distillation, and dry to obtain modified nano-titanium dioxide. Mix EPDM rubber and ethylene-vinyl acetate copolymer in a mixer for 3-5 min at a shaft temperature of 120-140℃, then add additives, vulcanizing aids, and the modified nano-titanium dioxide prepared in step (1); discharge the rubber at 100-110℃ to obtain masterbatch; mix the masterbatch rubber with antioxidant, accelerator, and vulcanizing agent in a two-roll open mill, then sheet the mixture and place it in a flat vulcanizing machine at 160-170℃ for 10-15 min to obtain EPDM rubber composite material.

[0009] Furthermore, in (1), the amount of 3-(3,4-dihydroxyphenyl) acrylate vinyl ester is 100 parts by weight, the amount of emulsifier is 1.2-2 parts by weight, and the amount of initiator is 0.4-0.7 parts by weight.

[0010] Furthermore, in (1), the initiator includes ammonium persulfate or potassium persulfate.

[0011] Furthermore, the emulsifier in (1) includes sodium dodecyl sulfate or sodium dodecylbenzene sulfonate.

[0012] Furthermore, in (1), the reaction temperature is 65-75℃ and the reaction time is 2-3h.

[0013] Furthermore, in (2), the temperature during heating and stirring is 50-70℃, and the time is 3-6h.

[0014] Furthermore, (2) the antioxidants include antioxidant 4010NA or antioxidant MB.

[0015] Furthermore, the accelerator in (2) includes accelerator CZ or accelerator TMTD.

[0016] Furthermore, in (2), the sulfiding agent is sulfur.

[0017] Furthermore, in (2), the sulfidation aid is stearic acid.

[0018] Furthermore, (2) adds zinc oxide as an auxiliary agent.

[0019] Furthermore, EPDM rubber composites are used in automotive sealing strips.

[0020] Beneficial technical effects of this invention: Under the action of initiators such as ammonium persulfate, the sterically hindered ethylene acetate groups of 3-(4-hydroxyphenyl)acrylate ( The self-polymerization reaction is carried out to obtain vinyl acetate polymers. The catechol groups of the polymers can coordinate with nano-titanium dioxide, thereby introducing polyvinyl acetate molecular chains on the surface of nano-titanium dioxide. Then, it is blended and vulcanized with EPDM rubber, ethylene-vinyl acetate copolymer, vulcanizing agent, and additives to obtain EPDM rubber composite material.

[0021] The titanium dioxide of this invention is grafted with polyvinyl acetate molecular chains, exhibiting excellent compatibility with ethylene-vinyl acetate copolymer (EVA). Both the EVA and EPDM contain polyethylene block molecular chains, demonstrating excellent compatibility. Furthermore, the compatibilizing effect of the EVA-vinyl acetate copolymer enhances the compatibility between the modified nano-titanium dioxide and EPDM, allowing the nano-titanium dioxide to be uniformly dispersed in the EVA-EPDM composite material, thus providing better reinforcement. The prepared EPDM composite material exhibits excellent hardness, tensile strength, elongation at break, and tear strength, making it more suitable for applications in the automotive industry, such as sealing strips. Detailed Implementation

[0022] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions in the embodiments of this application will be clearly and completely described below. Obviously, the described embodiments are some embodiments of this application, but not all embodiments.

[0023] The following are the grades of ethylene propylene diene monomer (EPDM) rubber: TER 4436. Ethylene-vinyl acetate copolymer grade: V5110J.

[0024] 3-(3,4-dihydroxyphenyl)vinyl acrylate and 3-(4-hydroxyphenyl)vinyl acrylate were prepared according to the method described in the article "Palladium(II) Acetate as Catalyst in Transvinylation Reactions of Hydroxycinnamic Acid and Its Derivatives" published in the Asian Journal of Chemistry; Vol. 30, No. 3 (2018), 589-593.

[0025] Add 194 mg of 3,4-dihydroxycinnamic acid, 1.4 g of vinyl acetate, and 9 mg of palladium acetate to 1 mL of tetrahydrofuran. Stir at room temperature for 30 min, then add 1 drop of a 10% (w / w) tetrahydrofuran solution of sulfuric acid. Stir and react at 40 °C for 4 h. Filter, and distill under reduced pressure. Separate the crude product by silica gel column chromatography, eluting with a 1:1 (v / v) solution of n-hexane and ethyl acetate to obtain 3-(3,4-dihydroxyphenyl)vinyl acrylate. The structural formula is... .

[0026] 164 mg of 4-hydroxycinnamic acid, 1.4 g of vinyl acetate, and 9 mg of palladium acetate were added to 1 mL of tetrahydrofuran. The mixture was stirred at room temperature for 30 min, then 1 drop of a 10% (w / w) tetrahydrofuran solution of sulfuric acid was added dropwise. The mixture was stirred at 40 °C for 4 h. After filtration, the filtrate was distilled under reduced pressure. The crude product was separated by silica gel column chromatography, eluted with a 2:1 (v / v) solution of n-hexane and ethyl acetate to obtain 3-(4-hydroxyphenyl)vinyl acrylate. The structural formula is... .

[0027] Example 1: (1) Add 5g of 3-(3,4-dihydroxyphenyl) vinyl acrylate (structural formula: 0.07 g sodium dodecylbenzenesulfonate was stirred and then 0.02 g ammonium persulfate was added under a nitrogen atmosphere. The mixture was heated to 75 °C and stirred for 2 h. After filtration, the mixture was washed with water and ethanol in sequence and dried to obtain vinyl acetate polymers.

[0028] (2) Add 20g of nano-titanium dioxide (average particle size 40nm, the same below) to 1.2L of toluene, disperse by ultrasonication, then add 4g of vinyl acetate polymer, heat to 50℃, stir for 6h, remove toluene by vacuum distillation, and dry to obtain modified nano-titanium dioxide.

[0029] (3) Mix 750g of EPDM rubber and 250g of ethylene-vinyl acetate copolymer in a mixer for 5 minutes at a shaft temperature of 130°C. Then add 70g of zinc oxide, 14g of stearic acid, and (2) the modified nano-titanium dioxide. Discharge the rubber at 100°C to obtain masterbatch. Mix the masterbatch with 25g of antioxidant MB, 12g of accelerator TMTD, and 18g of sulfur in a two-roll mill. After triangular wrapping, thinning, and sheeting, place the material in a flat vulcanizing machine and vulcanize at 160°C for 15 minutes to obtain EPDM rubber composite material.

[0030] Example 2: (1) Add 5g of 3-(3,4-dihydroxyphenyl) acrylate and 0.1g of sodium dodecylbenzenesulfonate to 50mL of water, stir, add 0.035g of potassium persulfate in a nitrogen atmosphere, heat to 65℃, stir and react for 3h, filter, wash with water and ethanol in turn, dry, and obtain vinyl acetate polymer.

[0031] (2) Add 50g of nano-titanium dioxide to 1.4L of toluene, disperse it by ultrasonication, then add 10g of vinyl acetate polymer, heat to 70℃, stir for 3h, remove toluene by vacuum distillation, and dry to obtain modified nano-titanium dioxide.

[0032] (3) Mix 650g of EPDM rubber and 350g of ethylene-vinyl acetate copolymer in a mixer for 3 minutes at a shaft temperature of 120°C. Then add 50g of zinc oxide, 20g of stearic acid, and (2) the modified nano-titanium dioxide prepared. Discharge the rubber at 100°C to obtain masterbatch. Mix the masterbatch with 20g of antioxidant MB, 15g of accelerator CZ, and 13g of sulfur in a two-roll mill. After triangular wrapping, thinning, and sheeting, place the material in a flat vulcanizing machine and vulcanize at 170°C for 10 minutes to obtain EPDM rubber composite material.

[0033] Example 3: (1) Add 5g of 3-(3,4-dihydroxyphenyl) acrylate and 0.06g of sodium dodecyl sulfate to 40mL of water, stir, add 0.027g of ammonium persulfate under a nitrogen atmosphere, heat to 70℃, stir and react for 3h, filter, wash with water and ethanol in turn, dry, and obtain vinyl acetate polymer.

[0034] (2) Add 80g of nano-titanium dioxide to 1.4L of toluene, disperse it by ultrasonication, then add 15g of vinyl acetate polymer, heat to 60℃, stir for 4h, remove toluene by vacuum distillation, and dry to obtain modified nano-titanium dioxide.

[0035] (3) Mix 550g of EPDM rubber and 450g of ethylene-vinyl acetate copolymer in a mixer for 5 minutes at a shaft temperature of 140℃. Then add 40g of zinc oxide, 16g of stearic acid, and (2) the modified nano titanium dioxide prepared. Discharge the rubber at 110℃ to obtain the masterbatch. Mix the masterbatch with 28g of antioxidant 4010NA, 10g of accelerator CZ, and 10g of sulfur in a two-roll mill. After triangular wrapping, thinning, and sheeting, place the material in a flat vulcanizing machine and vulcanize at 170℃ for 10 minutes to obtain EPDM rubber composite material.

[0036] Comparative Example 1 differs from Example 1 in that nano-titanium dioxide is not added.

[0037] (1) Mix 750g of EPDM rubber and 250g of ethylene-vinyl acetate copolymer in a mixer for 5 minutes at a shaft temperature of 130°C. Then add 70g of zinc oxide, 14g of stearic acid and 4g of vinyl acetate polymer. Discharge the rubber at 100°C to obtain masterbatch. Mix the masterbatch with 25g of antioxidant MB, 12g of accelerator TMTD and 18g of sulfur in a two-roll mill. After forming a triangular bundle, thinning and sheeting, place the material in a flat vulcanizing machine and vulcanize at 160°C for 15 minutes to obtain EPDM rubber material.

[0038] Comparative Example 2 differs from Example 1 in that it does not use vinyl acetate polymers to modify nano-titanium dioxide.

[0039] (1) Mix 750g of EPDM rubber and 250g of ethylene-vinyl acetate copolymer in a mixer for 5 minutes at a shaft temperature of 130°C. Then add 70g of zinc oxide, 14g of stearic acid and 20nm of titanium dioxide. Discharge the rubber at 100°C to obtain masterbatch. Mix the masterbatch with 25g of antioxidant MB, 12g of accelerator TMTD and 18g of sulfur in a two-roll mill. After forming a triangular bundle, thinning and sheeting, place the material in a flat vulcanizing machine and vulcanize at 160°C for 15 minutes to obtain EPDM rubber material.

[0040] Comparative Example 3: Nano-silica was modified with vinyl acetate polymers.

[0041] (1) Add 5g of 3-(4-hydroxyphenyl)vinyl acrylate (with the structural formula shown) to 40mL of water. 0.07 g sodium dodecylbenzenesulfonate was stirred and then 0.02 g ammonium persulfate was added under a nitrogen atmosphere. The mixture was heated to 75 °C and stirred for 2 h. After filtration, the mixture was washed with water and ethanol in sequence and dried to obtain vinyl acetate polymers.

[0042] (2) Add 20g of nano-titanium dioxide to 1.2L of toluene, disperse by ultrasonication, then add 4g of vinyl acetate polymer, heat to 50℃, stir for 6h, remove toluene by vacuum distillation, and dry to obtain vinyl acetate polymer-nano-titanium dioxide blend.

[0043] (3) Mix 750g of EPDM rubber and 250g of ethylene-vinyl acetate copolymer in a mixer for 5 minutes at a shaft temperature of 130°C. Then add 70g of zinc oxide, 14g of stearic acid, and (2) the vinyl acetate polymer-nano titanium dioxide blend prepared. Discharge the rubber at 100°C to obtain the masterbatch. Mix the masterbatch with 25g of antioxidant MB, 12g of accelerator TMTD, and 18g of sulfur in a two-roll mill. After triangular wrapping, thinning, and sheeting, place the material in a flat vulcanizing machine and vulcanize at 160°C for 15 minutes to obtain EPDM rubber material.

[0044] Comparative Example 4: Nano-silica was modified with conventional dopamine.

[0045] (1) Add 20g of nano titanium dioxide to 1.2L of water, disperse it by ultrasonication, then add 4g of dopamine hydrochloride, stir and add 3mL of Tris hydrochloride buffer solution, stir and react for 2h, dry to remove water, and obtain dopamine modified titanium dioxide.

[0046] (2) Mix 750g of EPDM rubber and 250g of ethylene-vinyl acetate copolymer in a mixer for 5 minutes at a shaft temperature of 130°C. Then add 70g of zinc oxide, 14g of stearic acid, and (1) the dopamine-modified nano-titanium dioxide prepared. Discharge the rubber at 100°C to obtain the masterbatch. Mix the masterbatch with 25g of antioxidant MB, 12g of accelerator TMTD, and 18g of sulfur in a two-roll mill. After triangular wrapping, thinning, and sheeting, place the material in a flat vulcanizing machine and vulcanize at 160°C for 15 minutes to obtain EPDM rubber material.

[0047] The Shore A hardness of the composite material was tested according to the national standard GB / T 531.1-2008.

[0048] Tensile properties were tested according to GB / T 528-2009. The tensile speed was 500 mm / min, and the test temperature was 25℃.

[0049] Tear resistance was tested according to GB / T 529-2008. The tensile speed was 500 mm / min, and the test temperature was 25℃.

[0050] Table 1 Properties of EPDM rubber materials

[0051] According to the test results in the table above, the ethylene-vinyl acetate copolymer-ethylene propylene diene monomer rubber material of Comparative Example 1 did not contain nano-titanium dioxide, and the Shore A hardness, tensile strength, elongation at break and tear strength of the material were relatively low.

[0052] Comparative Example 2 incorporated nano-titanium dioxide. Due to the aggregation of the nano-titanium dioxide solution, its compatibility with ethylene-vinyl acetate copolymer and ethylene propylene diene monomer (EPDM) rubber was poor, resulting in poor dispersion in the material and a low reinforcing effect. Hardness, tensile strength, elongation at break, and tear strength were not significantly improved.

[0053] Examples 1-3 utilize vinyl acetate polymers to surface modify nano-titanium dioxide. The catechol groups of the vinyl acetate polymer ( ) can coordinate with nano-titanium dioxide, thereby introducing polyvinyl acetate molecular chains onto the surface of nano-titanium dioxide. This process ensures good compatibility between nano-titanium dioxide and ethylene-vinyl acetate copolymer (EVA). Both EVA and EPDM contain polyethylene block chains, exhibiting excellent compatibility. Furthermore, the compatibilizing effect of the EVA-vinyl acetate copolymer further enhances the compatibility between the modified nano-titanium dioxide and EPDM, allowing for uniform dispersion of nano-titanium dioxide in the EVA-EPDM composite material. This results in improved reinforcement, significantly enhancing hardness, tensile strength, elongation at break, and tear strength.

[0054] The 3-(4-hydroxyphenyl)acrylate vinyl ester of Comparative Example 3 and the vinyl acetate polymers prepared therefrom do not contain catechol groups, making it difficult to effectively modify the surface of nano-titanium dioxide. This makes it impossible to improve the compatibility between titanium dioxide and ethylene-vinyl acetate copolymer and EPDM rubber, thus preventing the nano-titanium dioxide from being uniformly dispersed in the EVA-EPDM composite material. Consequently, the material exhibits lower hardness, tensile strength, elongation at break, and tear strength.

[0055] Comparative Example 4 uses conventional dopamine to modify nano-titanium dioxide. The polydopamine generated on the surface has a large difference in molecular chain structure with ethylene-vinyl acetate copolymer and EPDM rubber, which does not improve the compatibility between titanium dioxide and ethylene-vinyl acetate copolymer and EPDM rubber, resulting in low material hardness, tensile strength, elongation at break and tear strength.

[0056] The above are merely preferred embodiments of this application and are not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A ternary ethylene propylene diene monomer (EPDM) rubber composite material, characterized in that, The EPDM rubber composite material comprises 55-75 parts by weight of EPDM rubber, 25-45 parts by weight of ethylene-vinyl acetate copolymer, 2-8 parts by weight of nano titanium dioxide, 0.4-1.5 parts by weight of vinyl acetate polymer, 2-2.8 parts by weight of antioxidant, 1-1.8 parts by weight of vulcanizing agent, 1.4-2 parts by weight of vulcanizing aid, 1-1.5 parts by weight of accelerator, and 4-7 parts by weight of additives. The preparation process of the vinyl acetate polymer includes: adding 3-(3,4-dihydroxyphenyl) vinyl acrylate and emulsifier to water, stirring, adding an initiator under a nitrogen atmosphere, heating to the reaction temperature, stirring the reaction, filtering, washing, and drying to obtain the vinyl acetate polymer.

2. The EPDM rubber composite material according to claim 1, characterized in that, The amount of 3-(3,4-dihydroxyphenyl) acrylate vinyl ester used is 100 parts by weight, the amount of emulsifier is 1.2-2 parts by weight, and the amount of initiator is 0.4-0.7 parts by weight.

3. The EPDM rubber composite material according to claim 1, characterized in that, The initiator includes ammonium persulfate or potassium persulfate.

4. The EPDM rubber composite material according to claim 1, characterized in that, The emulsifier includes sodium dodecyl sulfate or sodium dodecylbenzene sulfonate.

5. The EPDM rubber composite material according to claim 1, characterized in that, The reaction temperature is 65-75℃, and the reaction time is 2-3 hours.

6. The EPDM rubber composite material according to claim 1, characterized in that, The antioxidants include antioxidant 4010NA or antioxidant MB; the accelerators include accelerator CZ or accelerator TMTD.

7. The EPDM rubber composite material according to claim 1, characterized in that, The vulcanizing agent includes sulfur; the vulcanizing aid includes stearic acid; and the additives include zinc oxide.

8. A preparation process for a ternary ethylene propylene diene monomer (EPDM) rubber composite material as described in any one of claims 1-7, characterized in that, The preparation process includes: Nano-titanium dioxide was added to toluene and ultrasonically dispersed. Then, vinyl acetate polymers were added, and the mixture was heated and stirred before vacuum distillation to remove the toluene. After drying, modified nano-titanium dioxide was obtained. EPDM rubber and ethylene-vinyl acetate copolymer were mixed in a mixer for 3-5 minutes at a shaft temperature of 120-140℃. Then, additives, vulcanizing aids, and modified nano-titanium dioxide were added. The mixture was discharged at 100-110℃ to obtain masterbatch. The masterbatch, antioxidant, accelerator, and vulcanizing agent were processed in a two-roll mill to form triangular bundles, thin sheets, and then placed in a flat vulcanizing mill. The material was vulcanized at 160-170℃ for 10-15 minutes to obtain EPDM rubber composite material.

9. The preparation process of the EPDM rubber composite material according to claim 8, characterized in that, The temperature during heating and stirring is 50-70℃, and the time is 3-6 hours.

10. The application of a EPDM rubber composite material obtained by the preparation process described in claim 9 in automotive sealing strips.

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