High-temperature-resistant vulcanized rubber and preparation method thereof

Abstract

The invention relates to the technical field of rubber, and discloses high-temperature-resistant vulcanized rubber and a preparation method thereof.The vulcanized rubber is prepared from, by weight, 80-65 parts of ethylene propylene diene monomer, 20-35 parts of fluororubber, 15-25 parts of fluorine-containing phytic acid modified natural rubber, 4.2-5.3 parts of vulcanizing agent and 0.52-0.96 part of vulcanizing aid. The fluorine-containing phytic acid modified natural rubber plays a role of a compatilizer, so that the interfacial compatibility between the ethylene propylene diene monomer and the fluororubber is improved, and the tearing strength and the mechanical property of the rubber material are improved. And the fluororubber and the ethylene propylene diene monomer form a high-compatibility blended rubber system, so that the high-temperature resistance of the rubber material can be improved. And the fluorine-containing phytic acid modified natural rubber contains a large number of phytic acid and phosphoric acid structures, and can play a role in condensed phase flame retardance as a phosphorus-containing flame retardant, so that the limit oxygen index and flame retardance of the rubber material are improved.

Description

Technical Field

[0001] The present invention relates to the technical field of rubber, and specifically to a heat-resistant vulcanized rubber and a preparation method thereof. Background Art

[0002] Ethylene propylene diene monomer (EPDM) rubber is a copolymer of ethylene, propylene, and non-conjugated diene, which has good water resistance, aging resistance, and mechanical properties, and is widely used in automotive parts, electronic components, cable sheath materials, building waterproof materials, etc. Improving the heat resistance, flame retardancy, mechanical strength and other properties of EPDM rubber can expand its practical application fields. Co-vulcanizing EPDM rubber with natural rubber, fluororubber, nitrile rubber, etc., the obtained blend rubber has better properties.

[0003] Fluororubber has excellent properties such as high temperature resistance, oxidation resistance, aging resistance, and corrosion resistance, and has important applications in the fields of aerospace, automotive industry, petrochemical industry, etc. However, the polarity difference between fluororubber and EPDM rubber is relatively large, and the two are incompatible systems, so a suitable compatibilizer needs to be added. Chinese Patent Application CN118063896A discloses a heat and humidity aging resistant EPDM rubber sealing material and a preparation method thereof. Using EPDM rubber, fluororubber, compatibilizer, plasticizer, MXene material, boron nitride inorganic filler, etc. as raw materials, the obtained EPDM rubber sealing material has good heat and humidity aging resistance and other properties, but this EPDM rubber treatment does not have good tear strength, flame retardancy and other properties. Summary of the Invention

[0004] The present invention solves the problem of poor heat resistance and other properties of EPDM rubber vulcanizate.

[0005] Technical Solution: A heat-resistant vulcanized rubber, comprising 80-65 parts by weight of EPDM rubber, 20-35 parts by weight of fluororubber, 15-25 parts by weight of fluorinated phytic acid modified natural rubber, 3.2-4.4 parts by weight of zinc oxide, 30-40 parts by weight of carbon black, 0.8-1 part by weight of stearic acid, 4.2-5.3 parts by weight of vulcanizing agent, 2-4 parts by weight of metal auxiliary agent, 0.52-0.96 part by weight of vulcanization auxiliary agent, 0.8-1 part by weight of accelerator.

[0006] Preferably, the preparation method of the high-temperature resistant vulcanized rubber is as follows: Mix ethylene propylene diene monomer rubber (EPDM), fluororubber, and fluorinated phytic acid-modified natural rubber in a Banbury mixer at a temperature of 90 - 100 °C and a rotation speed of 100 - 150 rpm; then add zinc oxide, carbon black, stearic acid, metal additives, and accelerators for mixing. Finally, add vulcanizing agents and vulcanization aids, discharge the rubber and cut it into sheets. Place it in a flat vulcanizer and vulcanize it at 160 - 170 °C under a pressure of 10 - 12 MPa for 10 - 15 minutes, and then place it in a hot air dryer and vulcanize it at 150 - 160 °C for 18 - 24 hours to obtain the high-temperature resistant vulcanized rubber.

[0007] Preferably, the preparation method of the fluorinated phytic acid-modified natural rubber is as follows: Add 100 parts by weight of epoxidized natural rubber, 10 - 25 parts by weight of phytic acid, and 8 - 20 parts by weight of glycidyl perfluorobutyl ether to a torque rheometer and mix at 70 - 80 °C for 30 - 60 minutes, then discharge to obtain the fluorinated phytic acid-modified natural rubber.

[0008] Preferably, the preparation method of glycidyl perfluorooctyl ether is as follows: In an ice-water bath, add 33 - 39 parts by weight of epichlorohydrin and 44 - 52 parts by weight of triethylamine to dichloromethane, and dropwise add a dichloromethane solution containing 100 parts by weight of perfluorobutyryl chloride. Then react at 10 - 15 °C for 24 - 30 hours, extract and wash with water, combine the organic phases, rotary evaporate, and dry to obtain glycidyl perfluorooctyl ether.

[0009] Preferably, the vulcanization aids include bisphenol AF and benzyltriphenylphosphonium chloride.

[0010] Preferably, the vulcanizing agents include dicumyl peroxide and triallyl isocyanurate.

[0011] Preferably, the metal additives include magnesium oxide and calcium hydroxide.

[0012] Preferably, the accelerators include accelerator DM and tetramethylthiuram disulfide.

[0013] The technical effect of the present invention is as follows: Using phytic acid as a bridging agent, during the high-temperature mixing process, its multiple phosphate groups respectively undergo ring-opening reactions with the epoxy groups of epoxidized natural rubber and glycidyl perfluorooctyl ether, thereby grafting phytic acid and glycidyl perfluorooctyl ether onto the molecular chain of natural rubber. Then, it is mixed and vulcanized with ethylene propylene diene monomer rubber (EPDM), fluororubber, vulcanizing agents, vulcanization aids, accelerators, etc. to obtain the high-temperature resistant vulcanized rubber.

[0014] The fluorinated phytic acid modified natural rubber of the present invention has good compatibility with ethylene propylene diene monomer (EPDM) rubber. At the same time, the fluorinated phytic acid modified natural rubber is grafted with a perfluoroalkyl chain, so that it also has similar polarity and good interfacial compatibility with fluororubber. The fluorinated phytic acid modified natural rubber plays the role of a compatibilizer, improving the interfacial compatibility between EPDM rubber and fluororubber, and enhancing the tear strength and mechanical properties of the rubber material.

[0015] The fluororubber of the present invention has excellent high temperature resistance and forms a high compatibility blend rubber system with EPDM rubber, which is beneficial to improving the high temperature resistance of the EPDM rubber material and showing a higher thermal decomposition temperature. And the fluorinated phytic acid modified natural rubber contains a large amount of phytic acid phosphate structure. As a phosphorus-containing flame retardant, it can play a role in condensed phase flame retardancy, improving the limiting oxygen index and flame retardant performance of the rubber material. Specific Embodiments

[0016] To make the objectives, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0017] In the specific embodiments, EPDM rubber and fluororubber are purchased from Dongguan Xinshengli Plastic New Material Technology Co., Ltd. Epoxidized natural rubber is purchased from Shandong Senya New Material Co., Ltd.

[0018] Example 1:

[0019] (1) In an ice-water bath, 3.3 g of glycidol and 4.4 g of triethylamine were added to 150 mL of dichloromethane, and an 80 mL dichloromethane solution containing 10 g of perfluorobutyryl chloride was added dropwise. Then the reaction was carried out at 15 °C for 24 h, followed by extraction and washing with water. The organic phases were combined, rotary evaporated, and dried to obtain glycidyl perfluorooctanoate.

[0020] (2) 200 g of epoxidized natural rubber, 20 g of phytic acid, and 16 g of glycidyl perfluorobutyrate were added to a torque rheometer and kneaded at 80 °C for 30 min, and then discharged to obtain fluorinated phytic acid modified natural rubber.

[0021] (3) Mix 800 g of ethylene propylene diene monomer rubber, 200 g of fluororubber, and 150 g of fluorinated phytic acid modified natural rubber in a Banbury mixer at a temperature of 90 °C and a rotation speed of 150 rpm; then add 32 g of zinc oxide, 350 g of carbon black, 10 g of stearic acid, 7 g of magnesium oxide, 13 g of calcium hydroxide, and 9.2 g of accelerator DM for mixing. Finally, add 17 g of dicumyl peroxide, 36 g of triallyl isocyanurate, 3.9 g of bisphenol AF, and 1.3 g of benzyltriphenylphosphonium chloride. After mixing, discharge the rubber and cut it into sheets. Place it in a flat vulcanizer and vulcanize it at 165 °C under a pressure of 12 MPa for 10 min, then place it in a hot air dryer and vulcanize it at 150 °C for 24 h to obtain a high-temperature resistant vulcanized rubber.

[0022] Example 2:

[0023] (1) In an ice-water bath, add 3.9 g of glycidol and 5.2 g of triethylamine to 150 mL of dichloromethane, dropwise add 100 mL of a dichloromethane solution containing 10 g of perfluorobutyryl chloride, and then react at 10 °C for 30 h. Extract and wash with water, combine the organic phases, rotary evaporate, and dry to obtain glycidyl perfluorooctanoate.

[0024] (2) Add 200 g of epoxidized natural rubber, 36 g of phytic acid, and 30 g of glycidyl perfluorobutyrate to a torque rheometer and mix at 80 °C for 40 min, then discharge to obtain fluorinated phytic acid modified natural rubber.

[0025] (3) Mix 720 g of ethylene propylene diene monomer rubber, 280 g of fluororubber, and 200 g of fluorinated phytic acid modified natural rubber in a Banbury mixer at a temperature of 90 °C and a rotation speed of 150 rpm; then add 44 g of zinc oxide, 400 g of carbon black, 8 g of stearic acid, 10 g of magnesium oxide, 22 g of calcium hydroxide, and 10 g of accelerator DM for mixing. Finally, add 15 g of dicumyl peroxide, 36 g of triallyl isocyanurate, 5.6 g of bisphenol AF, and 1.6 g of benzyltriphenylphosphonium chloride. After mixing, discharge the rubber and cut it into sheets. Place it in a flat vulcanizer and vulcanize it at 170 °C under a pressure of 10 MPa for 15 min, then place it in a hot air dryer and vulcanize it at 150 °C for 24 h to obtain a high-temperature resistant vulcanized rubber.

[0026] Example 3:

[0027] (1) In an ice-water bath, add 3.3 g of glycidol and 4.7 g of triethylamine to 150 mL of dichloromethane, dropwise add 80 mL of a dichloromethane solution containing 10 g of perfluorobutyryl chloride, and then react at 15 °C for 24 h. Extract and wash with water, combine the organic phases, rotary evaporate, and dry to obtain glycidyl perfluorooctanoate.

[0028] (2) Add 200 g of epoxy natural rubber, 50 g of phytic acid, and 40 g of epoxypropyl perfluorobutyl ester into a torque rheometer, mix at 70 °C for 60 min, discharge the material to obtain fluorinated phytic acid-modified natural rubber.

[0029] (3) Mix 650 g of ethylene propylene diene monomer rubber, 350 g of fluororubber, and 250 g of fluorinated phytic acid-modified natural rubber in an internal mixer at a temperature of 100 °C and a rotation speed of 100 rpm; then add 40 g of zinc oxide, 300 g of carbon black, 8 g of stearic acid, 13 g of magnesium oxide, 27 g of calcium hydroxide, and 8 g of tetramethylthiuram disulfide for mixing, and finally add 14 g of diisopropylbenzene peroxide, 28 g of triallyl isocyanurate, 7.4 g of bisphenol AF, and 2.2 g of benzyltriphenylphosphonium chloride. After mixing, discharge the rubber and cut it into sheets, place it in a flat vulcanizer, vulcanize at 160 °C under a pressure of 10 MPa for 15 min, and then place it in a hot air dryer and vulcanize at 160 °C for 18 h to obtain heat-resistant vulcanized rubber.

[0030] Comparative Example 1: The difference between this comparative example and Example 1 is that fluorinated phytic acid-modified natural rubber is not added.

[0031] (1) Mix 800 g of ethylene propylene diene monomer rubber and 200 g of fluororubber in an internal mixer at a temperature of 90 °C and a rotation speed of 150 rpm; then add 32 g of zinc oxide, 350 g of carbon black, 10 g of stearic acid, 7 g of magnesium oxide, 13 g of calcium hydroxide, and 9.2 g of accelerator DM for mixing, and finally add 17 g of diisopropylbenzene peroxide, 36 g of triallyl isocyanurate, 3.9 g of bisphenol AF, and 1.3 g of benzyltriphenylphosphonium chloride. After mixing, discharge the rubber and cut it into sheets, place it in a flat vulcanizer, vulcanize at 165 °C under a pressure of 12 MPa for 10 min, and then place it in a hot air dryer and vulcanize at 150 °C for 24 h to obtain heat-resistant vulcanized rubber.

[0032] Comparative Example 2: The difference between this comparative example and Example 1 is that epoxy natural rubber is used instead of fluorinated phytic acid-modified natural rubber.

[0033] (1) Mix 800 g of ethylene propylene diene monomer rubber and 200 g of fluororubber in an internal mixer at a temperature of 90 °C and a rotation speed of 150 rpm; then add 32 g of zinc oxide, 350 g of carbon black, 10 g of stearic acid, 7 g of magnesium oxide, 13 g of calcium hydroxide, and 9.2 g of accelerator DM for mixing, and finally add 17 g of diisopropylbenzene peroxide, 36 g of triallyl isocyanurate, 3.9 g of bisphenol AF, and 1.3 g of benzyltriphenylphosphonium chloride. After mixing, discharge the rubber and cut it into sheets, place it in a flat vulcanizer, vulcanize at 165 °C under a pressure of 12 MPa for 10 min, and then place it in a hot air dryer and vulcanize at 150 °C for 24 h to obtain heat-resistant vulcanized rubber.

[0034] Comparative Example 3: The difference between this comparative example and Example 1 is that when preparing phytic acid-modified natural rubber, glycidyl perfluorobutyl ester is not added.

[0035] (1) Add 200 g of epoxidized natural rubber and 20 g of phytic acid to a torque rheometer, mix at 80 °C for 30 min, and discharge to obtain phytic acid-modified natural rubber.

[0036] (2) Knead 800 g of ethylene-propylene-diene monomer rubber, 200 g of fluororubber, and 150 g of phytic acid-modified natural rubber in a mixer at a temperature of 90 °C and a rotation speed of 150 rpm; then add 32 g of zinc oxide, 350 g of carbon black, 10 g of stearic acid, 7 g of magnesium oxide, 13 g of calcium hydroxide, and 9.2 g of accelerator DM for kneading. Finally, add 17 g of dicumyl peroxide, 36 g of triallyl isocyanurate, 3.9 g of bisphenol AF, and 1.3 g of benzyltriphenylphosphonium chloride, knead and discharge the rubber, cut it into sheets, place it in a flat vulcanizer, vulcanize at 165 °C under a pressure of 12 MPa for 10 min, and then place it in a blast dryer and vulcanize at 150 °C for 24 h to obtain heat-resistant vulcanized rubber.

[0037] Comparative Example 4: The difference between this comparative example and Example 1 is that when preparing modified natural rubber, phytic acid is not added.

[0038] (1) Add 200 g of epoxidized natural rubber and 16 g of glycidyl perfluorobutyl ester to a torque rheometer, mix at 80 °C for 30 min, and discharge to obtain a modified natural rubber blend.

[0039] (2) Knead 800 g of ethylene-propylene-diene monomer rubber, 200 g of fluororubber, and 150 g of modified natural rubber blend in a mixer at a temperature of 90 °C and a rotation speed of 150 rpm; then add 32 g of zinc oxide, 350 g of carbon black, 10 g of stearic acid, 7 g of magnesium oxide, 13 g of calcium hydroxide, and 9.2 g of accelerator DM for kneading. Finally, add 17 g of dicumyl peroxide, 36 g of triallyl isocyanurate, 3.9 g of bisphenol AF, and 1.3 g of benzyltriphenylphosphonium chloride, knead and discharge the rubber, cut it into sheets, place it in a flat vulcanizer, vulcanize at 165 °C under a pressure of 12 MPa for 10 min, and then place it in a blast dryer and vulcanize at 150 °C for 24 h to obtain heat-resistant vulcanized rubber.

[0040] Test the tensile properties according to GB / T 528-2009.

[0041] Weigh 10 mg of vulcanized rubber and place it in a thermogravimetric analyzer for thermogravimetric analysis test. Heat it from 25 °C to 800 °C at a heating rate of 10 °C / min in a nitrogen atmosphere.

[0042] Test the oxygen index of vulcanized rubber according to GB / T 10707-2008.

[0043] Table 1 Tensile Property Test

[0044]

[0045]

[0046] T in the above table 5％ is the temperature at a mass fraction of 5%. T 10％ is the temperature at a mass fraction of 10%.

[0047] As can be seen from the above table, in each example, ethylene propylene diene monomer (EPDM) rubber and fluororubber are used as blended rubbers, and fluorinated phytic acid modified natural rubber is added. The main chain of natural rubber is cis-1,4-polyisoprene, and the main chain of EPDM rubber is polyethylene-propylene-non-conjugated diene. Therefore, the two have good compatibility. At the same time, the fluorinated phytic acid modified natural rubber is grafted with a perfluoroalkyl chain, so that it also has similar polarity and good interfacial compatibility with fluororubber. The fluorinated phytic acid modified natural rubber acts as a compatibilizer, improving the interfacial compatibility between EPDM rubber and fluororubber, enhancing the tear strength and mechanical properties of the rubber material. And fluororubber has excellent high-temperature resistance, forming a highly compatible blended rubber system with EPDM rubber, which is beneficial to improving the high-temperature resistance of EPDM rubber material and showing a higher thermal decomposition temperature. And the fluorinated phytic acid modified natural rubber contains a large number of phytic acid phosphate structures, which can act as a phosphorus-containing flame retardant in the condensed phase, improving the limiting oxygen index and flame retardant performance of the rubber material.

[0048] Compared with Example 1, in Comparative Example 1, fluorinated phytic acid modified natural rubber was not added, and the compatibility between EPDM rubber and fluororubber was poor, resulting in a lower tear strength of the rubber material. Moreover, the thermal decomposition temperature and limiting oxygen index were lower than those in Example 1, and the high-temperature resistance and flame retardancy were not good.

[0049] In Comparative Example 2, epoxy natural rubber was used to replace fluorinated phytic acid modified natural rubber. Epoxy natural rubber did not introduce a perfluoroalkyl chain, and there was a large polarity gap with fluororubber, resulting in poor interfacial compatibility and being unable to play the role of compatibilizing EPDM rubber and fluororubber. As a result, the tear strength of the rubber material was lower, and the thermal decomposition temperature and limiting oxygen index were lower than those in Example 1, and the high-temperature resistance and flame retardancy were not good.

[0050] The phytic acid modified natural rubber in Comparative Example 3 does not contain a perfluoroalkyl chain and cannot play the role of compatibilizing EPDM rubber and fluororubber, resulting in lower tear strength and thermal decomposition temperature of the rubber material.

[0051] The epoxy natural rubber of Comparative Example 4 and the epoxypropyl perfluorobutyl ester are difficult to react. After mixing, the two are in a blended state. The epoxy natural rubber does not graft the perfluoroalkyl chain and cannot play the role of compatibilizing ethylene propylene diene monomer rubber and fluororubber, resulting in a low tear strength of the rubber material. Moreover, the thermal decomposition temperature and the limiting oxygen index are lower than those of Example 1, and the high-temperature resistance and flame retardancy are not good.

[0052] The above are only the preferred embodiments of the present invention and do not impose any formal limitations on the present invention. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and refinements can be made, and these improvements and refinements should also be regarded as the protection scope of the present invention.

Claims

1. A high temperature resistant vulcanized rubber, characterized in that: The high temperature resistant vulcanized rubber comprises 80-65 parts by weight of EPDM rubber, 20-35 parts by weight of fluororubber, 15-25 parts by weight of fluorinated phytic acid modified natural rubber, 3.2-4.4 parts by weight of zinc oxide, 30-40 parts by weight of carbon black, 0.8-1 parts by weight of stearic acid, 4.2-5.3 parts by weight of vulcanizing agent, 2-4 parts by weight of metal additive, 0.52-0.96 parts by weight of vulcanizing additive, and 0.8-1 parts by weight of accelerator; The preparation method of the fluorinated phytic acid modified natural rubber comprises the following steps: adding epoxy natural rubber, phytic acid and epoxypropyl perfluorooctyl ester into a torque rheometer, mixing and discharging the mixture to obtain the fluorinated phytic acid modified natural rubber.

2. The high temperature resistant vulcanized rubber according to claim 1, characterized in that: The usage of the epoxy natural rubber is 100 parts by weight, the usage of phytic acid is 10-25 parts by weight, and the usage of epoxypropyl perfluorooctyl ester is 8-20 parts by weight.

3. The high temperature resistant vulcanized rubber according to claim 2, characterized in that: The mixing temperature is 70-80°C and the mixing time is 30-60 minutes.

4. The high temperature resistant vulcanized rubber according to claim 2, characterized in that: The preparation method of glycidol is as follows: in an ice water bath, glycidol and triethylamine are added to dichloromethane, a dichloromethane solution of perfluorobutyryl chloride is added dropwise, and then the mixture is reacted at 10-15° C. for 24-30 hours, extracted and washed with water, the organic phases are combined, rotary evaporated, and dried to obtain glycidyl perfluorooctyl ester.

5. The high temperature resistant vulcanized rubber according to claim 4, characterized in that: The dosage of the glycidol is 33-39 parts by weight, the dosage of the triethylamine is 44-52 parts by weight, and the dosage of the perfluorobutyryl chloride is 100 parts by weight.

6. The high temperature resistant vulcanized rubber according to claim 1, characterized in that: The vulcanization aids include bisphenol AF and benzyl triphenyl phosphonium chloride.

7. The high temperature resistant vulcanized rubber according to claim 1, characterized in that: The vulcanizing agent includes dicumyl peroxide and triallyl isocyanurate.

8. The high temperature resistant vulcanized rubber according to claim 1, characterized in that: The metal additives include magnesium oxide and calcium hydroxide.

9. The high temperature resistant vulcanized rubber according to claim 1, characterized in that: The accelerators include accelerator DM and tetramethylthiuram disulfide.

10. A method for preparing a high temperature resistant vulcanized rubber according to any one of claims 1 to 9, characterized in that: The preparation method comprises the following steps: kneading EPDM rubber, fluororubber and fluorinated phytic acid modified natural rubber in an internal mixer at a temperature of 90-100°C and a rotation speed of 100-150 rpm; then adding zinc oxide, carbon black, stearic acid, metal additives and accelerators for mixing; finally adding vulcanizing agent and vulcanizing aids; after mixing, the rubber is discharged and the sheets are removed; the sheets are placed in a flat vulcanizing press, vulcanized at 160-170°C and a pressure of 10-12 MPa for 10-15 minutes; and then placed in a blast dryer, vulcanized at 150-160°C for 18-24 hours to obtain high temperature resistant vulcanized rubber.

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