EPDM rubber material for sealing sheath and preparation method thereof

Abstract

The present invention provides an EPDM rubber material for a sealing sheath, which is made of the following raw materials in parts by weight: 40-50 parts of EPDM raw rubber, 25-35 parts of carbon black, 10-15 parts of filler, 10-20 parts of plasticizer, 0.5-1 parts of vulcanizer, and 0.5-1 parts of accelerator. The present invention also provides a preparation method of the EPDM rubber material. The EPDM rubber material for a sealing sheath provided by the present invention has good high-temperature modulus stability and flame retardant properties.

Description

Technical Field

[0001] The invention relates to a rubber material, in particular to an EPDM rubber material for a sealing sheath and a preparation method thereof. Background Art

[0002] The function of the automobile steering system is to ensure that the car can adapt to the road to change the direction of travel, or maintain stable straight driving during driving. The steering column is an important part of the automobile steering system, and the sealing sleeve used for the steering column must ensure its good sealing and stability, and can effectively prevent dust and other impurities from entering. At the same time, it can prevent grease from drying and leaking, thereby ensuring the normal operation of the steering column. The material currently used to manufacture the sealing sleeve is mainly EPDM rubber.

[0003] EPDM is a copolymer of ethylene, propylene and a small amount of non-conjugated dienes. It is a type of ethylene-propylene rubber, represented by EPDM. Because its main chain is composed of chemically stable saturated hydrocarbons and only contains unsaturated double bonds in the side chains, it has excellent aging resistance such as ozone resistance, heat resistance, and weather resistance. Compared with other commonly used general-purpose rubbers or special rubbers, the main performance advantages of EPDM are as follows: (1) High cost performance, with a raw rubber density of only 0.86 to 0.90 g / cm 3 , is the most commonly used rubber with the lightest raw density, and can be filled in large quantities to reduce the cost of rubber; (2) Excellent aging resistance, weather resistance, ozone resistance, sunlight resistance, heat resistance, water resistance, water vapor resistance, ultraviolet resistance, radiation resistance and other aging properties; (3) Excellent chemical resistance, acid, alkali, detergent, animal and vegetable oils, alcohol, ketone, etc., outstanding water resistance, superheated water resistance, water vapor resistance, polar oil resistance; (4) Excellent insulation performance, breakdown voltage 30-40MV / m, dielectric constant (1kHz, 20℃) 2.27. However, the existing EPDM rubber still has certain problems when used for sealing sheaths: the modulus is unstable at high temperature, which will affect the normal assembly efficiency of the product, and the flame retardant performance is poor. Summary of the invention

[0004] The technical problem to be solved by the present invention is to provide an EPDM rubber material for a sealing sheath, which has good high-temperature modulus stability and flame retardant performance.

[0005] In order to solve the above technical problems, the technical solution of the present invention is:

[0006] An EPDM rubber material for a sealing sheath is prepared from the following raw materials in parts by weight: 40-50 parts of EPDM raw rubber, 25-35 parts of carbon black, 10-15 parts of filler, 10-20 parts of plasticizer, 0.5-1 part of vulcanizer, and 0.5-1 part of accelerator.

[0007] Furthermore, the carbon black described in the present invention is carbon black N774.

[0008] Furthermore, the filler of the present invention is prepared by the following steps:

[0009] PVP was dissolved in deionized water and stirred for 3 hours to obtain a PVP solution. Zinc nitrate was added to the PVP solution and reacted in a water bath at 35°C for 3 hours with stirring to obtain a zinc solution. TEOS was added to the zinc solution and the pH value was adjusted to 2 and stirred for 1 hour, and then allowed to stand for 8 hours to obtain a hydrogel. The hydrogel was placed in a freezer and frozen for 12 hours, and then transferred to a freeze dryer and freeze-dried for 24 hours to obtain a filler.

[0010] Furthermore, in the preparation steps of the filler of the present invention, the ratio of PVP, deionized water, zinc nitrate and tetraethyl orthosilicate is 1g:40mL:8g:10g, the temperature of the freezer is -20°C, and the temperature of freeze drying is -60°C.

[0011] Furthermore, the plasticizer of the present invention is paraffin oil.

[0012] Furthermore, the vulcanizing agent of the present invention is S.

[0013] Furthermore, the accelerator of the present invention is accelerator DM.

[0014] Another technical problem to be solved by the present invention is to provide a method for preparing the EPDM rubber material for the sealing sheath.

[0015] To solve the above technical problems, the technical solution is:

[0016] A method for preparing an EPDM rubber material for a sealing sheath comprises the following steps:

[0017] S1 weighed the raw materials in parts by weight, the EPDM rubber on the open mill plasticized and wrapped roller, and then successively added carbon black, filler, plasticizer mixing for 10-15 minutes, and then added vulcanizing agent, accelerator continued mixing for 10-15 minutes to obtain a rubber mix;

[0018] S2. Adjust the roller distance to 5mm and pass the thick rubber obtained in step S1 6 times, then adjust the roller distance to 0.5mm and pass the thin rubber mix 8 times before feeding, and let it stand for 12 hours to obtain a film;

[0019] S3. Put the film obtained in step S2 on a flat vulcanizer, vulcanize it at 165° C. for 15-20 minutes and then at 155° C. for 4-5 hours to obtain an EPDM rubber material for a sealing sheath.

[0020] Compared with the prior art, the present invention has the following beneficial effects:

[0021] The filler used in the present invention is prepared by first preparing zinc nitrate, tetraethyl orthosilicate, PVP and the like into a precursor solution, then preparing the precursor solution into a hydrogel and then freeze-drying the hydrogel. The filler has a structure of zinc oxide composite silica aerogel. Compared with adding zinc oxide alone, the filler used in the present invention has better bonding with EPDM rubber, so the strength and modulus of the EPDM rubber material can be effectively improved. Moreover, the silica aerogel in the filler has a large specific surface area, a high porosity, and excellent heat resistance and flame retardancy, so the high-temperature modulus stability and flame retardancy of the EPDM rubber material can be effectively improved. DETAILED DESCRIPTION

[0022] The present invention will be described in detail below in conjunction with specific embodiments. The illustrative embodiments of the present invention and their descriptions are used to explain the present invention but are not intended to limit the present invention.

[0023] Example 1

[0024] The EPDM rubber material used for the sealing sheath is made of the following raw materials in parts by weight: 45 parts of EPDM raw rubber, 30 parts of carbon black N774, 12 parts of filler, 15 parts of paraffin oil, 0.8 parts of vulcanizing agent S, and 0.7 parts of accelerator DM.

[0025] The filler is prepared by the following steps:

[0026] PVP was dissolved in deionized water and stirred for 3 hours to obtain a PVP solution. Zinc nitrate was added to the PVP solution and reacted in a water bath at 35°C for 3 hours to obtain a zinc solution. Tetraethyl orthosilicate was added to the zinc solution, and the ratio of PVP, deionized water, zinc nitrate and tetraethyl orthosilicate was 1g:40mL:8g:10g. The pH value was adjusted to 2 and stirred for 1 hour, and then allowed to stand for 8 hours to obtain a hydrogel. The hydrogel was placed in a -20°C freezer and frozen for 12 hours, and then transferred to a freeze dryer and freeze-dried at -60°C for 24 hours to obtain a filler.

[0027] The preparation method of the EPDM rubber material for the sealing sheath comprises the following steps:

[0028] S1 weighed the raw materials in parts by weight, the EPDM rubber on the open mill and plasticized roll package, and then successively added carbon black N774, filler, paraffin oil mixing for 12 minutes, and then added vulcanizing agent S, accelerator DM continued mixing for 12 minutes to obtain a rubber mix;

[0029] S2. Adjust the roller distance to 5mm and pass the thick rubber obtained in step S1 6 times, then adjust the roller distance to 0.5mm and pass the thin rubber mix 8 times before feeding, and let it stand for 12 hours to obtain a film;

[0030] S3. Place the film obtained in step S2 on a flat vulcanizer, vulcanize at 165° C. for 18 minutes and then at 155° C. for 4.5 hours to obtain an EPDM rubber material for a sealing sheath.

[0031] Example 2

[0032] The EPDM rubber material used for the sealing sheath is made of the following raw materials in parts by weight: 48 parts of EPDM raw rubber, 25 parts of carbon black N774, 15 parts of filler, 12 parts of paraffin oil, 0.5 parts of vulcanizing agent S, and 0.6 parts of accelerator DM.

[0033] The preparation steps of the filler are the same as those in Example 1.

[0034] The preparation method of the EPDM rubber material for the sealing sheath comprises the following steps:

[0035] S1 weighed the raw materials in parts by weight, the EPDM rubber on the open mill and plasticized roll package, and then successively added carbon black N774, filler, paraffin oil mixing for 10 minutes, and then added vulcanizing agent S, accelerator DM continued mixing for 15 minutes to obtain a rubber mix;

[0036] S2. Adjust the roller distance to 5mm and pass the thick rubber obtained in step S1 6 times, then adjust the roller distance to 0.5mm and pass the thin rubber mix 8 times before feeding, and let it stand for 12 hours to obtain a film;

[0037] S3. Place the film obtained in step S2 on a flat vulcanizer, vulcanize at 165° C. for 15 minutes and then at 155° C. for 4.2 hours to obtain an EPDM rubber material for a sealing sheath.

[0038] Example 3

[0039] The EPDM rubber material used for the sealing sheath is made of the following raw materials in parts by weight: 40 parts of EPDM raw rubber, 35 parts of carbon black N774, 14 parts of filler, 20 parts of paraffin oil, 0.7 parts of vulcanizing agent S, and 0.5 parts of accelerator DM.

[0040] The preparation steps of the filler are the same as those in Example 1.

[0041] The preparation method of the EPDM rubber material for the sealing sheath comprises the following steps:

[0042] S1 weighed the raw materials in parts by weight, the EPDM rubber on the open mill plasticized and wrapped roller, and then successively added carbon black N774, filler, paraffin oil mixing for 15 minutes, and then added vulcanizing agent S, accelerator DM continued mixing for 10 minutes to obtain a rubber mix;

[0043] S2. Adjust the roller distance to 5mm and pass the thick rubber obtained in step S1 6 times, then adjust the roller distance to 0.5mm and pass the thin rubber mix 8 times before feeding, and let it stand for 12 hours to obtain a film;

[0044] S3. Put the film obtained in step S2 on a flat vulcanizer, vulcanize it at 165° C. for 20 minutes and then at 155° C. for 5 hours to obtain an EPDM rubber material for a sealing sheath.

[0045] Example 4

[0046] The EPDM rubber material used for the sealing sheath is made of the following raw materials in parts by weight: 50 parts of EPDM raw rubber, 27 parts of carbon black N774, 10 parts of filler, 10 parts of paraffin oil, 1 part of vulcanizing agent S, and 1 part of accelerator DM.

[0047] The preparation steps of the filler are the same as those in Example 1.

[0048] The preparation method of the EPDM rubber material for the sealing sheath comprises the following steps:

[0049] S1 weighed the raw materials in parts by weight, the EPDM rubber was plasticized on the open mill and rolled, and then carbon black N774, filler, paraffin oil were added and mixed for 11 minutes, and then the vulcanizing agent S and accelerator DM were added and mixed for 14 minutes to obtain a rubber mixture;

[0050] S2. Adjust the roller distance to 5mm and pass the thick rubber obtained in step S1 6 times, then adjust the roller distance to 0.5mm and pass the thin rubber mix 8 times before feeding, and let it stand for 12 hours to obtain a film;

[0051] S3. Put the film obtained in step S2 on a flat vulcanizer, vulcanize it at 165° C. for 16 minutes and then at 155° C. for 4 hours to obtain an EPDM rubber material for a sealing sheath.

[0052] Comparative Example 1

[0053] The difference from Example 1 is that the filler in the raw material is replaced by a mixture of zinc oxide and silicon dioxide aerogel in the same ratio as that of zinc oxide and silicon dioxide aerogel in the filler, and the step of preparing the filler is omitted.

[0054] Comparative Example 2

[0055] The difference from Example 1 is that the filler in the raw material is replaced by white carbon black, and the step of preparing the filler is omitted.

[0056] Experimental Example 1: Strength Test

[0057] Test reference standard / method: GB / T 528-2009.

[0058] Testing instrument: universal material testing machine.

[0059] Test object, target: tensile strength of the EPDM rubber materials prepared in Examples 1-4 and Comparative Example 1.

[0060] The test results are shown in Table 1:

[0061] Tensile strength (MPa) Example 1 15.4 Example 2 15.6 Example 3 15.3 Example 4 15.2 Comparative Example 1 14.1

[0062] Table 1

[0063] As can be seen from Table 1, the tensile strengths of Examples 1-4 of the present invention are all relatively high, indicating that the present invention has good strength. Part of the raw materials used in Comparative Example 1 are different from those in Example 1. Compared with Example 1, the tensile strength of Comparative Example 1 is reduced, indicating that the filler used in the present invention has a better effect on improving the strength of the EPDM rubber material than adding zinc oxide alone.

[0064] Experimental Example 2: Modulus Test

[0065] Test reference standard / method: GB / T 528-2009.

[0066] Testing instrument: universal material testing machine.

[0067] Test object, target: elastic modulus of the EPDM rubber materials prepared in Examples 1-4 and Comparative Example 1.

[0068] The test results are shown in Table 2:

[0069] Elastic modulus (MPa) Example 1 55.6 Example 2 55.9 Example 3 55.4 Example 4 55.3 Comparative Example 1 53.8

[0070] Table 2

[0071] As can be seen from Table 2, the elastic moduli of Examples 1-4 of the present invention are all relatively high, indicating that the present invention has a relatively high modulus. Part of the raw materials used in Comparative Example 1 are different from those in Example 1, and the elastic modulus of Comparative Example 1 is reduced compared with Example 1, indicating that the filler used in the present invention has a better effect on improving the modulus of the EPDM rubber material than adding zinc oxide alone.

[0072] Experimental Example 3: High Temperature Modulus Stability Test

[0073] Test reference standard / method: GB / T 3512—2014.

[0074] Test equipment: aging test chamber.

[0075] Test object, target: elastic modulus retention rate of the EPDM rubber materials prepared in Examples 1-4 and Comparative Example 2.

[0076] Test process: Put the EPDM rubber material into the aging test box, let it stand for 70 hours at 175℃, take it out, cool it naturally to room temperature, measure the elastic modulus again, and calculate the elastic modulus retention rate:

[0077] Elastic modulus retention rate = elastic modulus after aging / elastic modulus before aging × 100%.

[0078] The higher the elastic modulus retention rate, the better the high temperature modulus stability. The test results are shown in Table 3:

[0079] Elastic modulus retention rate (%) Example 1 85.3 Example 2 85.7 Example 3 85.5 Example 4 85.2 Comparative Example 1 82.6

[0080] Table 3

[0081] As can be seen from Table 3, the elastic modulus retention rates of Examples 1-4 of the present invention are all relatively high, indicating that the present invention has good high-temperature modulus stability. Part of the raw materials used in Comparative Example 2 are different from those in Example 1. Compared with Example 1, the elastic modulus retention rate of Comparative Example 2 is reduced, indicating that compared with ordinary white carbon black, the filler used in the present invention has a better effect on improving the high-temperature modulus stability of the EPDM rubber material.

[0082] Experimental Example 4: Flame retardant performance test

[0083] Test reference standard / method: GJB 323A-1996.

[0084] Test instrument: Oxygen-acetylene ablation rate tester.

[0085] Test object, target: mass ablation rate of the EPDM rubber materials prepared in Examples 1-4 and Comparative Example 2.

[0086] The lower the mass ablation rate, the better the flame retardant performance. The test results are shown in Table 4:

[0087] <![CDATA[Mass ablation rate (g·s -1 )]]> Example 1 6.484 Example 2 6.468 Example 3 6.502 Example 4 6.493 Comparative Example 2 7.976

[0088] Table 4

[0089] As can be seen from Table 4, the mass ablation rates of Examples 1-4 of the present invention are all low, indicating that the present invention has good flame retardant properties. Part of the raw materials used in Comparative Example 2 are different from those in Example 1. Compared with Example 1, the mass ablation rate of Comparative Example 2 is increased, indicating that compared with ordinary white carbon black, the filler used in the present invention has a better effect on improving the flame retardant properties of EPDM rubber materials.

[0090] The above embodiments are merely illustrative of the principles and effects of the present invention, and are not intended to limit the present invention. Anyone familiar with the art may modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by a person of ordinary skill in the art without departing from the spirit and technical concept disclosed by the present invention shall still be covered by the claims of the present invention.

Claims

1. An EPDM rubber material for a sealing sheath, characterized in that: The filler is made of the following raw materials in parts by weight: 40-50 parts of EPDM raw rubber, 25-35 parts of carbon black, 10-15 parts of filler, 10-20 parts of plasticizer, 0.5-1 part of vulcanizer, and 0.5-1 part of accelerator; the filler is made by the following steps: PVP was dissolved in deionized water, and the mixture was stirred for 3 hours to obtain a PVP solution. Zinc nitrate was added to the PVP solution, and the mixture was stirred in a water bath at 35°C for 3 hours to obtain a zinc solution. Tetraethyl orthosilicate was added to the zinc solution, and the pH value was adjusted to 2, and the mixture was stirred for 1 hour, and then the mixture was allowed to stand for 8 hours to obtain a hydrogel. The hydrogel was placed in a freezer and frozen for 12 hours, and then transferred to a freeze dryer and freeze-dried for 24 hours to obtain a filler. The ratio of PVP, deionized water, zinc nitrate, and tetraethyl orthosilicate was 1 g:40 mL:8 g:10 g. The temperature of the freezer was -20°C, and the temperature of freeze drying was -60°C.

2. The EPDM rubber material for a sealing sheath according to claim 1, characterized in that: The carbon black is carbon black N774.

3. The EPDM rubber material for a sealing sheath according to claim 1, characterized in that: The plasticizer is paraffin oil.

4. The EPDM rubber material for a sealing sheath according to claim 1, characterized in that: The vulcanizing agent is S.

5. The EPDM rubber material for a sealing sheath according to claim 1, characterized in that: The accelerator is accelerator DM.

6. A method for preparing an EPDM rubber material for a sealing sheath according to any one of claims 1 to 5, characterized in that: The following steps are involved: S1 weighed the raw materials in parts by weight, the EPDM rubber on the open mill plasticized and wrapped roller, and then successively added carbon black, filler, plasticizer mixing for 10-15 minutes, and then added vulcanizing agent, accelerator continued mixing for 10-15 minutes to obtain a rubber mix; S2. Adjust the roller distance to 5mm and pass the thick rubber obtained in step S1 6 times, then adjust the roller distance to 0.5mm and pass the thin rubber mix 8 times before feeding, and let it stand for 12 hours to obtain a film; S3. Put the film obtained in step S2 on a flat vulcanizer, vulcanize it at 165° C. for 15-20 minutes and then at 155° C. for 4-5 hours to obtain an EPDM rubber material for a sealing sheath.