High-temperature-resistant oil-resistant nitrile rubber / ethylene propylene rubber alloy material, preparation method thereof and sealing product

Abstract

The invention discloses a high-temperature-resistant oil-resistant nitrile rubber / ethylene propylene rubber alloy material, a preparation method thereof and a sealing product. The alloy material is prepared from the following components in parts by mass: 70 to 90 parts of nitrile rubber, 10 to 30 parts of ethylene propylene rubber, 5 to 15 parts of maleic anhydride grafted ethylene propylene rubber (EPDM-g-MAH), 40 to 80 parts of carbon black N550, 5 to 8 parts of zinc oxide, 2 to 5 parts of stearic acid, 10 to 20 parts of ester plasticizer, 1 to 3 parts of microcrystalline wax, 1 to 3 parts of anti-aging agent RD, 1 to 3 parts of anti-aging agent MB, 2 to 5 parts of vulcanizing agent DCP and 1 to 2 parts of crosslinking aid TAIC. By introducing EPDM-g-MAH as a compatilizer, adopting a peroxide vulcanization system and combining a three-stage mixing process, the compatibility and co-vulcanization efficiency of nitrile rubber and ethylene propylene rubber are remarkably improved, and the obtained material has excellent high-temperature resistance, oil resistance and ozone aging resistance and is suitable for the high-requirement field of automobile engine sealing and the like.

Description

Technical Field

[0001] This invention relates to the field of rubber materials technology, specifically to a high-temperature and oil-resistant nitrile rubber / ethylene propylene rubber alloy material, its preparation method and sealing products, which are particularly suitable for automotive engine sealing systems. Background Technology

[0002] Nitrile butadiene rubber (NBR) is widely used in sealing products due to its excellent oil resistance and airtightness. However, its high-temperature resistance is limited (long-term operating temperature does not exceed 120℃), and its ozone resistance and weather resistance are poor, making it difficult to meet the high requirements of modern automotive engines for sealing materials. Ethylene propylene diene monomer (EPDM), while heat and aging resistant, has poor oil resistance. Current technologies attempt to blend NBR and EPDM to balance their properties, but due to the significant differences in their polarity and vulcanization rates, direct blending easily leads to poor compatibility and difficulty in co-vulcanization, affecting the final performance. Summary of the Invention

[0003] The purpose of this invention is to overcome the shortcomings of the prior art and provide a high-temperature and oil-resistant nitrile rubber / ethylene propylene rubber alloy material, its preparation method, and sealing products that have excellent high-temperature resistance, oil resistance, and ozone aging resistance, so as to solve the problems mentioned in the background art.

[0004] To achieve the above objectives, the present invention provides the following technical solution: a high-temperature and oil-resistant nitrile rubber / ethylene propylene rubber alloy material, comprising the following components by mass parts:

[0005] 70–90 parts of nitrile rubber,

[0006] 10–30 parts of ethylene propylene rubber,

[0007] Maleic anhydride-grafted EPDM-g-MAH rubber 5–15 parts

[0008] Carbon black N550 40–80 parts,

[0009] 5–8 parts zinc oxide

[0010] Stearic acid 2–5 parts,

[0011] 10–20 parts of ester plasticizer,

[0012] 1–3 parts microcrystalline wax

[0013] Anti-aging agent RD 1–3 parts,

[0014] Anti-aging agent MB 1–3 parts,

[0015] Vulcanizing agent DCP 2–5 parts,

[0016] Crosslinking aid TAIC 1–2 parts.

[0017] Furthermore, the nitrile rubber is selected from at least one of NBR1052, NBR3345, or N230S.

[0018] Furthermore, the preparation method of the EPDM-g-MAH includes:

[0019] The melt grafting reaction was carried out at 170°C for 10 minutes at a mass ratio of EPDM:MAH:DCP = 100:0.25:2.5.

[0020] After granulation and extrusion, the product was ultrasonically treated with acetone solvent at 60°C for 24 hours, and then vacuum dried at 80°C for 12 hours to obtain the purified product.

[0021] Furthermore, its composition is preferably as follows:

[0022] 85 parts nitrile rubber, 15 parts ethylene propylene rubber, 5 parts EPDM-g-MAH, 60 parts carbon black N550, 5 parts zinc oxide, 2 parts stearic acid, 12 parts ester plasticizer, 1.5 parts microcrystalline wax, 1.5 parts antioxidant RD, 1.5 parts antioxidant MB, 3 parts vulcanizing agent DCP, and 1.5 parts crosslinking aid TAIC.

[0023] Furthermore, its composition is as follows: 80 parts nitrile rubber, 20 parts ethylene propylene rubber, 8 parts maleic anhydride grafted ethylene propylene rubber (EPDM-g-MAH), 60 parts carbon black N550, 5 parts zinc oxide, 2 parts stearic acid, 12 parts ester plasticizer, 1.5 parts microcrystalline wax, 1.5 parts antioxidant RD, 1.5 parts antioxidant MB, 3 parts vulcanizing agent DCP, and 1.8 parts crosslinking aid TAIC.

[0024] Furthermore, its composition is as follows: 70 parts nitrile rubber, 30 parts ethylene propylene rubber, 12 parts maleic anhydride grafted ethylene propylene rubber (EPDM-g-MAH), 60 parts carbon black N550, 5 parts zinc oxide, 2 parts stearic acid, 10 parts ester plasticizer, 1.5 parts microcrystalline wax, 1.5 parts antioxidant RD, 1.5 parts antioxidant MB, 3.5 parts vulcanizing agent DCP, and 1.5 parts crosslinking aid TAIC.

[0025] The present invention also provides a method for preparing the above-mentioned high-temperature and oil-resistant nitrile rubber / ethylene propylene rubber alloy material, comprising the following steps:

[0026] a) First stage of mixing: Nitrile rubber, ethylene propylene rubber and EPDM-g-MAH are put into an internal mixer and mixed for 60-90 seconds. Then carbon black, plasticizer and other small materials are added and mixed evenly before sheeting.

[0027] b) Second stage of mixing: After the rubber compound obtained in step a has been left to stand for no less than 8 hours, it is put into the internal mixer again for refining. After thorough mixing, it is sheeted out.

[0028] c) Third stage of mixing: Add the vulcanizing agent DCP and crosslinking aid TAIC to the rubber compound obtained in step b, mix evenly and then discharge the rubber to obtain the alloy material.

[0029] Furthermore, in the three-stage mixing process, the mixing temperature of each stage is controlled at 80–120℃.

[0030] The present invention also provides a sealing article made of the above-mentioned alloy material, the article being suitable for high-temperature oily environments at 125°C.

[0031] This invention introduces maleic anhydride-grafted ethylene propylene rubber (EPDM-g-MAH) as a compatibilizer, optimizes the vulcanization system (using a DCP / TAIC peroxide system), and designs a three-stage mixing process, which significantly improves the compatibility of the two phases and the co-vulcanization efficiency, thereby obtaining a rubber alloy material with excellent comprehensive performance. Detailed Implementation

[0032] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0033] In the field of polymer science, "alloy" or "polymer alloy" is a specific technical term used to analogize with metal alloys. It specifically refers to a multiphase system with a microscopic phase separation structure formed by physical blending or chemical methods of two or more polymers, aiming to obtain comprehensive properties not possessed by a single component. The blend of nitrile rubber (NBR) and ethylene propylene rubber (EPDM) in this case is a typical polymer alloy. In the rubber and plastics industries, as well as related academic and patent literature, the terms "rubber alloy" and "plastic alloy" (such as PC / ABS alloy) are very common, and their meanings are well known and understood by those skilled in the art. The "alloy material" in this invention can also be called a "blend" or "composite material."

[0034] A high-temperature and oil-resistant nitrile rubber / ethylene propylene rubber alloy material, comprising the following components by mass parts:

[0035] 70–90 parts of nitrile rubber,

[0036] 10–30 parts of ethylene propylene rubber,

[0037] Maleic anhydride-grafted EPDM-g-MAH rubber 5–15 parts

[0038] Carbon black N550 40–80 parts,

[0039] 5–8 parts zinc oxide

[0040] Stearic acid 2–5 parts,

[0041] 10–20 parts of ester plasticizer,

[0042] 1–3 parts microcrystalline wax

[0043] Anti-aging agent RD 1–3 parts,

[0044] Anti-aging agent MB 1–3 parts,

[0045] Vulcanizing agent DCP 2–5 parts,

[0046] Crosslinking aid TAIC 1–2 parts.

[0047] Furthermore, the nitrile rubber is selected from at least one of NBR1052, NBR3345, or N230S.

[0048] Furthermore, the preparation method of the EPDM-g-MAH includes:

[0049] The melt grafting reaction was carried out at 170°C for 10 minutes at a mass ratio of EPDM:MAH:DCP = 100:0.25:2.5.

[0050] After granulation and extrusion, the product was ultrasonically treated with acetone solvent at 60°C for 24 hours, and then vacuum dried at 80°C for 12 hours to obtain the purified product.

[0051] Furthermore, its composition is preferably as follows:

[0052] 85 parts nitrile rubber, 15 parts ethylene propylene rubber, 5 parts EPDM-g-MAH, 60 parts carbon black N550, 5 parts zinc oxide, 2 parts stearic acid, 12 parts ester plasticizer, 1.5 parts microcrystalline wax, 1.5 parts antioxidant RD, 1.5 parts antioxidant MB, 3 parts vulcanizing agent DCP, and 1.5 parts crosslinking aid TAIC.

[0053] Furthermore, its composition is as follows: 80 parts nitrile rubber, 20 parts ethylene propylene rubber, 8 parts maleic anhydride grafted ethylene propylene rubber (EPDM-g-MAH), 60 parts carbon black N550, 5 parts zinc oxide, 2 parts stearic acid, 12 parts ester plasticizer, 1.5 parts microcrystalline wax, 1.5 parts antioxidant RD, 1.5 parts antioxidant MB, 3 parts vulcanizing agent DCP, and 1.8 parts crosslinking aid TAIC.

[0054] Furthermore, its composition is as follows: 70 parts nitrile rubber, 30 parts ethylene propylene rubber, 12 parts maleic anhydride grafted ethylene propylene rubber (EPDM-g-MAH), 60 parts carbon black N550, 5 parts zinc oxide, 2 parts stearic acid, 10 parts ester plasticizer, 1.5 parts microcrystalline wax, 1.5 parts antioxidant RD, 1.5 parts antioxidant MB, 3.5 parts vulcanizing agent DCP, and 1.5 parts crosslinking aid TAIC.

[0055] The present invention also provides a method for preparing the above-mentioned high-temperature and oil-resistant nitrile rubber / ethylene propylene rubber alloy material, comprising the following steps:

[0056] a) First stage of mixing: Nitrile rubber, ethylene propylene rubber and EPDM-g-MAH are put into an internal mixer and mixed for 60-90 seconds. Then carbon black, plasticizer and other small materials are added and mixed evenly before sheeting.

[0057] b) Second stage of mixing: After the rubber compound obtained in step a has been left to stand for no less than 8 hours, it is put into the internal mixer again for refining. After thorough mixing, it is sheeted out.

[0058] c) Third stage of mixing: Add the vulcanizing agent DCP and crosslinking aid TAIC to the rubber compound obtained in step b, mix evenly and then discharge the rubber to obtain the alloy material.

[0059] Furthermore, in the three-stage mixing process, the mixing temperature of each stage is controlled at 80–120℃.

[0060] The present invention also provides a sealing article made of the above-mentioned alloy material, the article being suitable for high-temperature oily environments at 125°C.

[0061] This invention introduces maleic anhydride-grafted ethylene propylene rubber (EPDM-g-MAH) as a compatibilizer, optimizes the vulcanization system (using a DCP / TAIC peroxide system), and designs a three-stage mixing process, which significantly improves the compatibility of the two phases and the co-vulcanization efficiency, thereby obtaining a rubber alloy material with excellent comprehensive performance.

[0062] The present invention will be further illustrated by the following examples, but should not be construed as limiting the scope of protection of the present invention.

[0063] Examples 1–4

[0064] Weigh each component according to the proportions shown in Table 1, and prepare the alloy material according to the following steps:

[0065] 1. First stage of mixing: Put NBR, EPDM, and EPDM-g-MAH into the internal mixer and mix for 70 seconds;

[0066] 2. Add carbon black, plasticizer, zinc oxide, stearic acid, microcrystalline wax, antioxidant RD and MB, and continue mixing until uniform, then sheet.

[0067] 3. Second stage of mixing: After the rubber compound has been left to stand for 8 hours, it is mixed again and refined for 5 minutes before sheeting.

[0068] 4. Third stage of mixing: Add DCP and TAIC, mix evenly, then discharge the adhesive and vulcanize to form the final product.

[0069] The performance test results of the obtained materials are shown in Table 2, which show excellent heat aging resistance, oil resistance and ozone resistance.

[0070] Table 1: Formulation Tables for Examples 1–4 (parts by weight)

[0071]

[0072]

[0073] Table 2: Performance test results of the rubber compounds prepared in Examples 1-4

[0074] Test Project Example 1 Example 2 Example 3 Example 4 Hardness (Shore A) 72 70 68 69 Tensile strength (MPa) 18.2 17.5 15.8 16.3 Elongation at break (%) 305 352 387 365 Volume change rate (%) of 903# oil 3.2 4.1 6.5 5.7 Hardness changes after thermal aging +6 +4 +3 +3 Change rate of tensile strength after heat aging -7.5％ -5.9％ -2.5％ -3.2％ Elongation change rate after heat aging -22％ -18％ -12％ -12％ Ozone resistance (50 pphm, 72 h) No cracks No cracks No cracks No cracks

[0075] As shown in Table 2, the hardness of the adhesive compound of this invention is between 70±5 Shore A, the tensile strength is ≥15MPa, and the elongation at break is ≥250%, exhibiting excellent basic physical and mechanical properties. Furthermore, the tensile strength change rate during hot air aging (125℃×72h) is within -20% to 0, the elongation change rate is within -30% to 0, the volume change rate in 903# oil (125℃*72h) is ≤10%, and the ozone resistance test at 50pphm×40℃×72h shows no cracking. Therefore, the present invention exhibits excellent high-temperature resistance, superior oil resistance, and strong ozone resistance, making it suitable for use as a high-temperature and oil-resistant sealing adhesive.

[0076] This invention uses a blend of ethylene propylene rubber (EPR) and nitrile rubber (NBR), with maleic anhydride grafted onto the EPR to improve their compatibility and give the compound excellent oil resistance and aging resistance. The combined use of antioxidants RD and MB further enhances the compound's aging resistance. Due to the significant differences in unsaturation and polarity between EPR and NBR, sulfur vulcanization makes it difficult to balance the vulcanization rates of the two rubbers, severely impacting the final compound's performance. Therefore, this invention employs peroxide vulcanization. The vulcanizing agent DCP has good solubility in both rubbers, and the peroxide vulcanization reaction mechanism is free radical vulcanization, exhibiting low selectivity for the rubbers, allowing for better co-vulcanization and resulting in a compound with excellent physical properties. Furthermore, an additional refining step in the mixing process improves the compatibility of NBR and EPR, further enhancing the compound's performance.

[0077] The above technical solutions enable the present invention to achieve the following performance:

[0078] 1. Hardness 70±5 Shore A;

[0079] 2. Tensile strength ≥ 15 MPa;

[0080] 3. Elongation at break ≥ 250%;

[0081] 4. Hot air aging at 125℃ for 72 hours;

[0082] Hardness variation: ±10 Shore A;

[0083] Tensile strength change rate: -20% to 0

[0084] Change in elongation at break: -30% to 0

[0085] 5. Resistant to 903# oil at 125℃ for 72 hours:

[0086] Volume change rate ≤10%

[0087] 6. Ozone resistance: 50pphm × 40℃ × 72h without cracking.

[0088] The above performance characteristics indicate that the present invention has good high temperature resistance, excellent oil resistance, and strong ozone resistance, making it suitable for use as a high temperature and oil resistant sealing compound.

[0089] This invention, through dual innovation in material formulation and process, successfully prepared NBR / EPDM alloy material with excellent comprehensive performance, significantly broadening its application prospects in the field of high-temperature oil-resistant sealing.

[0090] The above are merely preferred embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A high-temperature and oil-resistant nitrile rubber / ethylene propylene rubber alloy material, characterized in that, By mass parts, it includes the following components: 70–90 parts of nitrile rubber, 10–30 parts of ethylene propylene rubber, Maleic anhydride-grafted EPDM-g-MAH rubber 5–15 parts Carbon black N550 40–80 parts, 5–8 parts zinc oxide Stearic acid 2–5 parts, 10–20 parts of ester plasticizer, 1–3 parts microcrystalline wax Anti-aging agent RD 1–3 parts, Anti-aging agent MB 1–3 parts, Vulcanizing agent DCP 2–5 parts, Crosslinking aid TAIC 1–2 parts.

2. The high-temperature and oil-resistant nitrile rubber / ethylene propylene rubber alloy material according to claim 1, characterized in that, The nitrile rubber is selected from at least one of NBR1052, NBR3345 or N230S.

3. The high-temperature resistant and oil-resistant nitrile rubber / ethylene propylene rubber alloy material according to claim 1 or 2, characterized in that, The preparation method of the EPDM-g-MAH includes: The melt grafting reaction was carried out at 170°C for 10 minutes at a mass ratio of EPDM:MAH:DCP = 100:0.25:2.

5. After granulation and extrusion, the product was ultrasonically treated with acetone solvent at 60°C for 24 hours, and then vacuum dried at 80°C for 12 hours to obtain the purified product.

4. The high-temperature and oil-resistant nitrile rubber / ethylene propylene rubber alloy material according to claim 1 or 2, characterized in that, Its preferred composition is: 85 parts nitrile rubber, 15 parts ethylene propylene rubber, 5 parts EPDM-g-MAH, 60 parts carbon black N550, 5 parts zinc oxide, 2 parts stearic acid, 12 parts ester plasticizer, 1.5 parts microcrystalline wax, 1.5 parts antioxidant RD, 1.5 parts antioxidant MB, 3 parts vulcanizing agent DCP, and 1.5 parts crosslinking aid TAIC.

5. The high-temperature resistant and oil-resistant nitrile rubber / ethylene propylene rubber alloy material according to claim 1 or 2, characterized in that, Its composition is as follows: 80 parts nitrile rubber, 20 parts ethylene propylene rubber, 8 parts maleic anhydride grafted ethylene propylene rubber (EPDM-g-MAH), 60 parts carbon black N550, 5 parts zinc oxide, 2 parts stearic acid, 12 parts ester plasticizer, 1.5 parts microcrystalline wax, 1.5 parts antioxidant RD, 1.5 parts antioxidant MB, 3 parts vulcanizing agent DCP, and 1.8 parts crosslinking aid TAIC.

6. The high-temperature resistant and oil-resistant nitrile rubber / ethylene propylene rubber alloy material according to claim 1 or 2, characterized in that, Its composition is as follows: 70 parts nitrile rubber, 30 parts ethylene propylene rubber, 12 parts maleic anhydride grafted ethylene propylene rubber (EPDM-g-MAH), 60 parts carbon black N550, 5 parts zinc oxide, 2 parts stearic acid, 10 parts ester plasticizer, 1.5 parts microcrystalline wax, 1.5 parts antioxidant RD, 1.5 parts antioxidant MB, 3.5 parts vulcanizing agent DCP, and 1.5 parts crosslinking aid TAIC.

7. A method for preparing the high-temperature resistant and oil-resistant nitrile rubber / ethylene propylene rubber alloy material as described in any one of claims 1-6, characterized in that, Includes the following steps: a) First stage of mixing: Nitrile rubber, ethylene propylene rubber and EPDM-g-MAH are put into an internal mixer and mixed for 60-90 seconds. Then carbon black, plasticizer and other small materials are added and mixed evenly before sheeting. b) Second stage of mixing: After the rubber compound obtained in step a has been left to stand for no less than 8 hours, it is put into the internal mixer again for refining. After thorough mixing, it is sheeted out. c) Third stage of mixing: Add the vulcanizing agent DCP and crosslinking aid TAIC to the rubber compound obtained in step b, mix evenly and then discharge the rubber to obtain the alloy material.

8. The method according to claim 7, characterized in that, In the three-stage mixing process, the mixing temperature of each stage is controlled at 80–120℃.

9. A sealing article made of the alloy material according to any one of claims 1-6, characterized in that, The product is suitable for use in oily environments at 125°C.

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