High-airtightness modified ethylene propylene diene monomer rubber used in low-temperature environment and preparation method of high-airtightness modified ethylene propylene diene monomer rubber

Abstract

The invention provides a high-airtightness modified ethylene propylene diene monomer rubber used in a low-temperature environment and a preparation method thereof. Polymerization monomers of the modified ethylene propylene diene monomer are ethylene, propylene and a modified monomer respectively; the epoxy group is grafted on the ethylene propylene diene monomer, so that good chemical stability can be provided, the low-temperature resistance of the rubber can be improved, and the sealing performance of the rubber can be enhanced; the grafted silicon group can enhance the weather resistance and low-temperature stability of the ethylene propylene diene monomer, and also has a certain improvement effect on the sealing property of the rubber; the modified ethylene propylene diene monomer is obtained through polymerization reaction of ethylene, propylene and a modified monomer, the crosslinking degree can be increased, and the sealing performance of the rubber is enhanced; and by controlling the molar ratio of the three, good mechanical properties at low temperature are maintained, and the application field is widened.

Description

Technical Field

[0001] The present invention relates to the technical field of polymer materials, and particularly relates to a modified ethylene propylene diene monomer (EPDM) rubber for low-temperature environments and high airtightness and a preparation method thereof. Background Art

[0002] Ethylene propylene diene monomer (EPDM) is a synthetic rubber polymerized from ethylene, propylene, and a small amount of non-conjugated diene monomers (such as propenyltriene). Due to its unique structure, EPDM is widely used in many industrial fields, especially its excellent weather resistance, aging resistance, chemical corrosion resistance, and good electrical insulation properties. EPDM plays an important role in multiple industries such as automotive, construction, electronics, medical, and consumer goods.

[0003] In the automotive industry, EPDM is widely used in components such as sealing strips, gaskets, hoses, and tires. Due to its good resistance to ultraviolet rays, ozone, and high-temperature aging, it can effectively extend the service life of components. In the construction industry, EPDM is used as roof waterproof membranes, window seals, etc., to resist various harsh environments with its excellent weather resistance and low-temperature performance. In the electronics and electrical fields, EPDM is used as the insulating material for cables, providing good electrical isolation and chemical resistance.

[0004] Although EPDM shows significant advantages in multiple fields, there are certain problems in its use at low temperatures. The low-temperature performance of EPDM is restricted by the material's own structure. Especially when the temperature decreases, the activity of its molecular chains weakens, resulting in a significant reduction in the flexibility and ductility of the rubber. Especially in environments below -40°C, EPDM becomes more brittle and is prone to cracking and brittle fracture. This limits its application in some cold regions. For example, automotive sealing strips and outdoor building materials in the northern regions often need to be modified or enhanced to improve their low-temperature performance.

[0005] Therefore, improving the low-temperature performance of EPDM remains a challenge. Traditional modification methods, such as adding fillers or other copolymers, can improve its low-temperature performance to a certain extent, but often sacrifice other properties, such as aging resistance or elasticity. Therefore, how to improve the low-temperature use ability of EPDM without affecting other properties is an important research direction at present. Summary of the Invention

[0006] Object of the Invention: The object of the present invention is to provide a modified EPDM rubber for low-temperature environments and high airtightness and a preparation method thereof. By modifying the polymer chain structure, the elasticity and sealing performance of EPDM rubber in low-temperature environments can be improved.

[0007] Technical Solution of the Present Invention:

[0008] In a first aspect, the present invention provides a modified ethylene propylene diene monomer (EPDM) rubber for low-temperature environments and high airtightness. The polymerization monomers of the modified EPDM rubber are ethylene, propylene, and a modified monomer represented by Formula 1:

[0009]

[0010] Wherein, n represents any integer from 4 to 9.

[0011] Further, n represents any one of 4, 6, and 9.

[0012] In some embodiments, the molar ratio of ethylene, propylene, and the modified monomer represented by Formula 1 in the modified EPDM rubber is 12 - 15:9 - 12:2 - 5.

[0013] Further, the molar ratio of ethylene, propylene, and the modified monomer represented by Formula 1 in the modified EPDM rubber is 12 - 13:9 - 10:2 - 3.

[0014] In some embodiments, the molecular weight of the modified EPDM rubber is 50,000 - 150,000.

[0015] The epoxy group can provide good chemical stability and improve the low-temperature resistance of the rubber. At the same time, the epoxy group can also enhance the sealing performance of the rubber; the silicon group can enhance the weather resistance and low-temperature stability of the EPDM rubber, and also has a certain improvement effect on the sealing performance of the rubber.

[0016] In some embodiments, the preparation method of the modified monomer includes the following steps:

[0017] S1: Add the silane coupling agent to deionized water and dissolve it; add an acidic catalyst and continuously stir at room temperature for hydrolysis reaction;

[0018] S2: Dissolve 1,5-deoxyxylitol in the solution, and slowly add the reaction solution of S1 to the 1,5-deoxyxylitol solution, and continue to stir and react under heating;

[0019] S3: After the reaction is completed, filter the reaction solution and dry it under vacuum to obtain the required modified monomer.

[0020] In some embodiments, the silane coupling agent is selected from one or more combinations of 5-alkenylhexyltrimethoxysilane (CAS: 58751-56-7), 7-alkenyloctyltrimethoxysilane (CAS: 52217-57-9), 10-alkenylundecyltrimethoxysilane (CAS: 872575-06-9).

[0021] In some embodiments, the molar ratio of the silane coupling agent to 1,5-deoxyxylitol is 1:3 - 3.2.

[0022] In some embodiments, continue to stir and react S2 under heating, the heating temperature is 40 - 60°C, and the heating time is 0.5 - 2 h.

[0023] In a second aspect, the present invention provides a method for preparing the modified ethylene-propylene-diene monomer rubber as described above, and the specific steps are as follows:

[0024] S1: Add a solvent to a reaction kettle, then add ethylene, propylene, and a modified monomer, and disperse them evenly; add a catalyst;

[0025] S2: Heat and pressurize the reaction kettle to carry out the reaction; after the reaction is completed, evaporate the solvent to obtain the modified ethylene-propylene-diene monomer rubber.

[0026] In some embodiments, the reaction temperature of S2 is 60 - 100°C, and the reaction pressure is 2 - 4 MPa.

[0027] Beneficial effects:

[0028] 1. By grafting epoxy groups onto the ethylene-propylene-diene monomer rubber, good chemical stability can be provided, the low-temperature resistance of the rubber can be improved, and the sealing performance of the rubber can also be enhanced; grafting silicon groups can enhance the weather resistance and low-temperature stability of the ethylene-propylene-diene monomer rubber, and at the same time, it also has a certain improvement effect on the sealing performance of the rubber.

[0029] 2. The modified ethylene-propylene-diene monomer rubber obtained by the polymerization reaction of ethylene, propylene, and a modified monomer can increase the crosslinking degree and enhance the sealing performance of the rubber; by controlling the molar ratio of the three, good mechanical properties at low temperatures can be maintained, and the application field can be broadened. Specific embodiments

[0030] The following will illustrate the present invention in conjunction with specific implementation schemes. It should be noted that the following examples are examples of the present invention, only for illustrating the present invention, and not for limiting the present invention. Without departing from the gist or scope of the present invention, other combinations and various improvements within the inventive concept of the present invention can be made.

[0031] Unless otherwise specified, the chemical reagents used in the present invention are all ordinary commercially available analytical pure.

[0032] Preparation example of modified monomer 1

[0033] S1: Add 3.1 mol of 5-alkenylhexadecyltrimethoxysilane to 100 ml of deionized water and dissolve it; add 1 mol of hydrochloric acid and continuously stir at room temperature for 30 min to carry out the hydrolysis reaction;

[0034] S2: Dissolve 1 mol of 1,5-deoxyxylitol in 50 ml of water, slowly add the reaction solution of S1 into the 1,5-deoxyxylitol solution, and continue stirring the reaction at 40 °C for 1 h;

[0035] S3: After the reaction is completed, vacuum-dry the reaction solution to obtain the required modified monomer 1.

[0036] Perform infrared spectrum analysis on modified monomer 1. According to the infrared spectrum analysis, it can be obtained that: at 3450 cm -1 the vibration peak of the alcohol hydroxyl group in 1,5-deoxyxylitol disappears; at 1140 cm -1 an absorption peak generated by the stretching vibration of the silicon-oxygen bond (Si-O) is formed; at 1655 cm -1 the absorption peak generated by C=C (olefin) is present; at 1280 cm -1 the absorption peak generated by Si-C is present. From the above analysis, it can be obtained that the infrared spectrum data proves that 5-alkenylhexyltrimethoxysilane is grafted onto three alcohol hydroxyl groups of 1,5-deoxyxylitol, and modified monomer 1 is successfully prepared.

[0037] The structural formula of modified monomer 1 is as shown in Formula 1-1.

[0038]

[0039] Preparation example of modified monomer 2

[0040] Basically the same as Preparation Example 1, the difference is that 7-alkenyloctyltrimethoxysilane is used to replace 5-alkenylhexyltrimethoxysilane to prepare modified monomer 2.

[0041] The structural formula of modified monomer 2 is as shown in Formula 1-2.

[0042]

[0043] Preparation example of modified monomer 3

[0044] Basically the same as Preparation Example 1, the difference is that 10-alkenylundecyltrimethoxysilane is used to replace 5-alkenylhexyltrimethoxysilane to prepare modified monomer 3.

[0045] The structural formula of modified monomer 3 is as shown in Formula 1-3.

[0046]

[0047] Example 1

[0048] S1: Add 20 L of cyclohexane into a reactor, introduce 132 mol of ethylene, 99 mol of propylene, add 22 mol of modified monomer 1, and add 0.03 mol of catalyst (the molar ratio of titanocene dichloride to triethylaluminum is 1:20);

[0049] S2: Heat the reactor to 80 °C and pressurize it to 3 MPa, and react for 4 h; after the reaction, evaporate the solvent to obtain modified ethylene-propylene-diene monomer rubber 1.

[0050] Example 2

[0051] Basically the same as Example 1, the difference is that modified monomer 2 is used to replace modified monomer 1 to prepare modified ethylene-propylene-diene monomer rubber 2.

[0052] Example 3

[0053] Basically the same as Example 1, the difference is that modified monomer 3 is used to replace modified monomer 1 to prepare modified ethylene-propylene-diene monomer rubber 3.

[0054] Example 4

[0055] Basically the same as Example 1, the difference is that the added molar amounts of ethylene, propylene, and modified monomer 1 are 143 mol, 110 mol, and 33 mol respectively to prepare modified ethylene-propylene-diene monomer rubber 4.

[0056] Example 5

[0057] Basically the same as Example 1, the difference is that the added molar amounts of ethylene, propylene, and modified monomer 1 are 165 mol, 132 mol, and 55 mol respectively to prepare modified ethylene-propylene-diene monomer rubber 5.

[0058] Comparative Example 1

[0059] Basically the same as Example 1, the difference is that the added molar amounts of ethylene, propylene, and modified monomer 1 are 143 mol, 110 mol, and 77 mol respectively to prepare modified ethylene-propylene-diene monomer rubber 6.

[0060] Comparative Example 2

[0061] Basically the same as Example 1, the difference is that the added molar amounts of ethylene, propylene, and modified monomer 1 are 143 mol, 110 mol, and 11 mol respectively to prepare modified ethylene-propylene-diene monomer rubber 7.

[0062] Comparative Example 3

[0063] Market-available ethylene-propylene-diene monomer rubber LANXESS 2650.

[0064]

[0065] ​By mass parts, 50 parts of the rubber materials obtained in the examples and comparative examples were respectively taken, and heated and vulcanized (175 °C, 15 min) with 2 parts of dicumyl peroxide, 50 parts of carbon black, 4 parts of paraffin oil, and 5 parts of zinc oxide to make standard test pieces. After being placed at room temperature for 3 months, the following performance tests were carried out.

[0066] 1. Tensile strength test was carried out at room temperature according to GB / T 528.

[0067] 2. Brittleness test was carried out at -65 °C according to GB / T 15256.

[0068] 3. The gas permeability coefficient of the standard test piece was tested according to GB / T 1038. The test sample was a circle with a diameter of 5 cm, and the thickness was averaged by 5-point measurement. The test gas was nitrogen, the test temperature was 40 °C, and the degassing time was 12 h.

[0069] 4. Low-temperature retraction performance test was carried out according to GB / T7758-2020. TR10 corresponds to the temperature when the sample retracts by 10%.

[0070] Table 1 Test results

[0071]

[0072] Compared with the comparative examples, the low-temperature resistance of the rubber materials in Examples 1-4 was significantly improved. In particular, TR10 could reach -60 to -64 °C, and the nitrogen sealing performance was more excellent than that of the commercially available products, indicating that the formulation of the present invention could improve the low-temperature resistance of the sealing rubber material and meet the sealing requirements in extremely cold and high-temperature environments.

[0073] Compared with Comparative Examples 1-2, the tensile strength and nitrogen sealing performance of the sealing rubber material in the examples were significantly improved, indicating that the modified monomer was helpful to improve the low-temperature sealing performance of the modified rubber material. Compared with Examples 4-5, it was found that when the molar ratio of ethylene, propylene and the modified monomer shown in Formula 1 in the modified ethylene-propylene-diene rubber was 13:10:3, the tensile strength and sealing performance of the rubber material at low temperature could be more balanced, making the rubber material not easy to become brittle and having better use conditions.

[0074] The present invention can also have other various embodiments. Without departing from the spirit and essence of the present invention, those skilled in the art can make various corresponding changes and deformations according to the present invention, but these corresponding changes and deformations should all fall within the protection scope of the appended claims of the present invention.

Claims

1. A modified ethylene propylene diene monomer rubber for low-temperature environment and high airtightness, characterized in that Comprising: The polymerization monomers of the modified ethylene propylene diene monomer rubber are ethylene, propylene and a modified monomer as shown in Formula 1: Wherein, n represents any integer from 4 to 9.

2. The modified ethylene-propylene-diene monomer rubber according to claim 1, wherein Said n represents any one of 4, 6, 9.

3. The modified ethylene-propylene-diene monomer rubber according to claim 1, wherein In the modified ethylene propylene diene monomer rubber, the molar ratio of ethylene, propylene and the modified monomer as shown in Formula 1 is 12 - 15:9 - 12:2 - 5.

4. The modified ethylene propylene diene monomer rubber according to claim 3, wherein The molar ratio of ethylene, propylene and the modified monomer as shown in Formula 1 is 12 - 13:9 - 10:2 - 3.

5. The modified ethylene propylene diene monomer rubber according to claim 3, wherein, The molecular weight of the modified ethylene propylene diene monomer rubber is 50000 - 150000.

6. The modified ethylene propylene diene monomer rubber according to claim 1, wherein, The preparation method of the modified monomer comprises the following steps: S1: Add the silane coupling agent into deionized water and dissolve it; add an acidic catalyst and continuously stir at room temperature for hydrolysis reaction; S2: Dissolve 1,5 - deoxymannitol in the solution, slowly add the reaction solution of S1 into the 1,5 - deoxymannitol solution, and continue stirring the reaction under heating; S3: After the reaction is completed, filter the reaction solution and dry it under vacuum to obtain the required modified monomer.

7. The modified ethylene-propylene-diene monomer rubber according to claim 6, wherein, The silane coupling agent is selected from one or more combinations of 5 - alkenyl hexyltrimethoxysilane, 7 - alkenyl octyltrimethoxysilane, 10 - alkenyl undecyltrimethoxysilane.

8. The modified ethylene-propylene-diene monomer rubber according to claim 6, wherein, The molar ratio of the silane coupling agent to 1,5 - deoxymannitol is 1:3 - 3.

2.

9. The modified ethylene-propylene-diene monomer rubber according to claim 6, wherein For the continued stirring reaction under heating in S2, the heating temperature is 40 - 60 °C and the heating time is 0.5 - 2 h.

10. The preparation method of the modified ethylene propylene diene monomer rubber according to any one of claims 1-9, characterized in that, Comprising the following steps: S1: Add a solvent into the reaction kettle, then add ethylene, propylene and the modified monomer, and disperse them evenly; add a catalyst; S2: Heat and pressurize the reaction kettle for reaction; after the reaction is completed, evaporate the solvent to obtain the modified ethylene propylene diene monomer rubber.

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