KR100619247B1 - The polyacrylate rubber composition of oil seal for auto transmission - Google Patents

Abstract

The present invention relates to a rubber composition for oil seals used in an automatic transmission, and more particularly, to a rubber matrix, comprising a polyacrylate rubber having a pattern viscosity (ML1 + 4, 100 ° C) of 40 to 50, and a particle diameter as a filler. By including the carbon black FEF of 40 to 48 mm and dry silica having a particle diameter of 7 to 16 nm, not only an oil seal having improved heat resistance, pressure resistance and oil resistance can be obtained, but also no second vulcanization step is required in the production of the oil seal. The present invention relates to a rubber composition for oil seals used in automatic transmissions, which has been improved so that the vulcanization time is significantly reduced, thereby improving productivity and reducing production costs.

Automatic transmission, oil seal, polyacrylate rubber, carbon black, dry silica

Description

The polyacrylate rubber composition of oil seal for auto transmission

The present invention relates to a rubber composition for oil seals used in an automatic transmission, and more particularly, to a rubber matrix, comprising a polyacrylate rubber having a pattern viscosity (ML1 + 4, 100 ° C) of 40 to 50, and a particle diameter as a filler. By including the carbon black FEF of 40 to 48 mm and dry silica having a particle diameter of 7 to 16 nm, not only an oil seal having improved heat resistance, pressure resistance and oil resistance can be obtained, but also no second vulcanization step is required in the production of the oil seal. The present invention relates to a rubber composition for oil seals used in automatic transmissions, which has been improved so that the vulcanization time is significantly reduced, thereby improving productivity and reducing production costs.

Transmission is a device that changes the rotational speed and torque of the output shaft, also called transmission. In general, the internal combustion engine for automobiles has a maximum torque at a constant speed, and when running, it requires strong torque and low rotation, and as the speed increases, the rotation speed is required rather than torque. Therefore, when starting with gears to maintain the constant rotation of the engine, a transmission is required, which reduces the rotational speed and increases the torque and increases the rotation as the speed increases. One type of transmission is an automatic transmission. Also known as a torque converter or a no-clutch, an automatic transmission is applied to a rotational speed by applying the properties of a fluid, unlike a gear type transmission in which a clutch and a gear must be changed every time a shift is performed. And a device that converts and transmits torque.

The oil seal is a product mounted on the automatic transmission to prevent leakage and at the same time deliver the hydraulic pressure of the clutch. In other words, an oil seal is a mechanical element that literally seals oil. Oil is placed in the friction part of the transmission to facilitate machine operation, and oil seals are used to prevent the oil from leaking out of the gaps in the machine. It is also used to prevent leakage of water or chemicals or to prevent foreign matter from entering the machine.

The oil seal is a functional part requiring heat resistance and oil resistance (resistance to auto transmission fluid) because it is exposed to high temperature oil at 100 to 150 ° C. and the hydraulic pressure of the clutch must be transmitted. Moreover, with the recent lightening and miniaturization of automotive parts and the extended warranty period for automobiles, the industry is able to withstand increased heat loads and improves heat resistance, pressure resistance and oil resistance that do not deteriorate with long-term use. Is asking.

Research on rubber compositions for oil seals has been steadily made. Initially, ethylene acryl-based rubber having excellent heat resistance and oil resistance was used as a rubber matrix, but this was limited because it was expensive and had poor workability. Accordingly, efforts have been made to lower the manufacturing cost by mixing ethylene propylene diene rubber (EPDM) with ethylene acrylic rubber (Korean Patent No. 10-0330917). This technology has been able to produce a relatively low cost oil seal, but there was a limit in the workability and the problem of low strength.

In addition, Korean Patent Laid-Open Publication No. 2004-0056562 proposed that the inclusion of clay having a particle size of 100 nm or less as a filler in the rubber composition for oil seal can effectively increase the strength of the oil seal while reducing the amount of use. However, even in this case, since the first and second vulcanization steps had to go through, respectively, the productivity of the product was lowered and the production cost was also high.

Accordingly, the present inventors have researched and tried to solve such a conventional problem, and use a polyacrylate rubber having a pattern viscosity (ML1 + 4, 100 ° C.) increased to 40 to 50 as a rubber matrix, and a particle size of 40 as a filler. The combination of carbon black FEF with a diameter of 48 mm and dry silica provides not only oil seal products with improved heat resistance, pressure resistance and oil resistance, but also significantly reduces vulcanization time since the process does not require a second vulcanization step. The present invention has been accomplished by knowing that cost and productivity can be improved.                         

Therefore, the present invention is obtained by adding carbon black FEF having a particle size of 40 to 48 mm and dry silica having a particle size of 7 to 16 nm as a filler to a polyacrylate rubber having a pattern viscosity (ML1 + 4, 100 ° C) of 40 to 50 mm. It is an object of the present invention to provide a rubber composition for oil seals used in an automatic transmission.

In addition, an object of the present invention is to provide an oil seal for use in an automatic transmission, characterized in that it is made of the composition.

The present invention is 100 parts by weight of polyacrylate rubber having a pattern viscosity (ML1 + 4, 100 ° C.) of 40 to 50; 75 to 85 parts by weight of carbon black FEF having a particle diameter of 40 to 48 mm; And a rubber composition for oil seal used in an automatic transmission including 3 to 10 parts by weight of dry silica.

The present invention will be described in more detail as follows.

The present invention comprises a polyacrylate rubber having a pattern viscosity (ML1 + 4, 100 ° C.) of 40 to 50 in a rubber matrix, and a carbon black FEF having a particle size of 40 to 48 mm with a filler and a dryness of 7 to 16 nm. The inclusion of silica not only results in oil seals with improved heat resistance, pressure resistance and oil resistance, but also eliminates the need for a second vulcanization step in the manufacture of the oil seals, resulting in significantly reduced vulcanization time resulting in improved productivity and reduced production costs. It relates to a rubber composition for oil seals used in automatic transmissions.

In this invention, polyacrylate rubber whose pattern viscosity (ML1 + 4, 100 degreeC) is 40-50 is used. The oil seal rubber used in the automatic transmission has high heat resistance and oil resistance and high pressure resistance at the same time as it has to play a role of preventing the flow of high temperature oil at 100 to 150 ° C and transmitting the hydraulic pressure of the clutch. Polyacrylate rubbers are suitable. In particular, the use of polyacrylate rubber having a pattern viscosity (ML1 + 4, 100 ° C.) of 40 to 50 results in a significant shortening of the vulcanization time.

In addition, when using a PA402A grade polyacrylate rubber with improved pattern viscosity than before, the workability of the composition is significantly improved, it can be expected that the effect of not having to go through the secondary vulcanization step.

When the pattern viscosity of the polyacrylate rubber is increased to 40 to 50 as in the present invention, tensile strength and elongation are improved, and heat resistance and oil resistance tend to be improved. On the other hand, the compression set, one of the important properties of rubber, is deteriorated. In order to compensate for the deterioration of the pressure resistance, carbon black FEF having a particle diameter of 40 to 48 mm and dry silica are used as fillers.

The filler of the present invention is to supplement mechanical strength and to supplement physical properties such as pressure resistance, and carbon black FEF means fast extrusion furnace when classified according to ASTM (AMERICAN STANDARD TEST METHOD) and its particle size is 40 It corresponds to-48 nm. Carbon black FEF has the advantages of excellent workability such as extrusion and molding, low heat generation and good thermal conductivity. Carbon black FEF is preferably included 75 to 85 parts by weight based on 100 parts by weight of polyacrylate rubber. If the content is less than 75 parts by weight, it is difficult to expect the improvement of physical properties such as heat resistance and strength. If the content is more than 85 parts by weight, cracking is likely to occur during external impact and the elasticity may be adversely affected to improve the pressure resistance. have.

Dry silica is used as another filler. Dry silica is a kind of white filler, and in the present invention, dry silica having a particle diameter of 7 to 16 nm is used to exhibit excellent reinforcement. Aerosil # 130, Aerosil # 150, Aerosil # 200, Aerosil # 300 and the like may be preferably used for the dry silica of the present invention. It is preferable that dry silica contains 3-10 weight part with respect to 100 weight part of polyacrylate rubbers. If the content is less than 3 parts by weight, it is difficult to expect the effect of improving physical properties such as heat resistance and strength. If the content is more than 10 parts by weight, cracking is likely to occur during external impact and the elasticity may be adversely affected to improve the pressure resistance.

In addition to the above components, the composition of the present invention may contain a crosslinking agent and an anti-aging agent which are commonly used in the rubber composition for oil seals used in the automatic transmission.

As the anti-aging agent, diphenylamine, 2-mercaptomethylbenzimidazole, etc. may be used, and 3 to 10 parts by weight, more preferably 100 parts by weight of the polyacrylate rubber. It is preferable to use 4-6 weight part. As the crosslinking agent, sulfur (Sulfur) or the like is commonly used, and a crosslinking aid such as stearic acid (Stearic acid) may be used together to assist the action of the crosslinking agent. It is good to use 5-13 weight part with respect to 100 weight part of said polyacrylate rubbers, More preferably, 6-8 weight part.

In the composition of the present invention, in addition to the additives used above, various other additives may be used within the scope of the object of the present invention.

On the other hand, look at the method of producing an oil seal with a composition according to the invention as follows. The manufacturing method of the oil seal of this invention is not limited to a special method, It can manufacture by a normal mechanical kneading method etc. For example, the composition is mixed using a general kneader such as a kneader, a Banbury mixer, an open mill, or the like, and is carried out at a kneading temperature of 100 to 150 ° C. It exhibits the most effective physical properties within the above temperature range, and the oil seal rubber composition kneaded above may be molded by a molding process such as cutting or extrusion molding.

Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to Examples.

Examples and Comparative Examples

Next, the rubber composition for preparing the oil seal used in the automatic transmission was mixed using the mechanical kneading method with the ingredients and contents of Table 1 below. In order to measure the physical properties of the composition prepared from the composition, after extrusion molding, it was cooled to prepare an oil seal specimen.

Ingredients (parts by weight) Comparative example Example 1                                              Example 2 Rubber ACM 1 ¹ 100 - - ACM 2 ² - 100 100 Filler Carbon Black N774 ³ 70 - - Carbon Black N550 ⁴ - 78 65 Aerosil # 200 ⁵ - 6 10 Anti-aging Sunnoc ⁶ - 2 2 CD ⁷ 2 2 2 Crosslinking aid DLP ⁸ 3 - - Stearic acid ⁹ One 2 2 Crosslinking agent Sulfur ¹⁰ 2 One One NS-Soap ¹¹ 3 4 5 Plasticizer RS 700 ¹² 3 -  1. ACM 1: Noxtite PA 402S, Unimatec, Pattern Viscosity 35 to 40 2. ACM 2: Noxtite PA 402A, Unimatec, Pattern Viscosity 40 to 50 3. N774: SRF, Dongyang Steel Chemical 4. N550: FEF, Donghae Carbon 5 Aerosil # 200: SiO2, Degussa Germany 6. Sunnoc: Wax-based, Emerging Emerging 7. CD: Diphenylamine, Emerging Emerging 8. DLP: Dibasic Lead Phosphite 9. Stearic Acid: Microsynthetic 10. Sulfur : Sulfur compound, Miwon Corporation 11. NS-Soap: fatty acid soda, king of Japan 12. RS 700: ether ester, ADK (Asahi Denka Kogyo)

Test Example

The physical properties of the compositions obtained in Comparative Examples and Examples were measured by the following test methods, and the results are shown in Table 2.

[How to measure]

1. Hardness: Clause 7 of KS M6518, KS Standard

2. Tensile strength: Clause 5 of KS M6518, KS standard

3. Elongation: Clause 5 of KS M6518, KS standard

4. Heat resistance: Clause 8 of KS M6518, KS standard

5. Oil resistance: Clause 13 of KS M6518, KS standard

6. Pressure resistance: A high pressure rod tester was used, and an automatic transmission oil (ATF DEXRON III) was used. Pressurize for 1.7 seconds at a temperature of 150 ° C, pressure of 1 MPa and relative relief of 8.4 Rz, hold for 3 seconds, and depressurize for 1.7 seconds for 10 seconds to repeat the amount of tightening, hardness and leakage. Measured.

division Comparative example Example 1 Example 2 Cross-linking conditions Primary crosslinking 180 ° C x 8 minutes 190 ° C × 4 minutes 190 ° C x 2 minutes Secondary crosslinking 150 ° C × 15 hours none none Heat resistance Hardness change (Point) +10 +6 +4 Tensile Strength Change Rate (%) +25 +11 +9 Elongation rate of change (%) -28 -10 -5 Oil Resistance (ATF) Hardness change (Point) -16 -7 -4 Tensile Strength Change Rate (%) -20 -10 -5 Elongation rate of change (%) +32 +21 +16 Volume change rate (%) +19 +8 +5 Pressure resistance Fastening amount (mm) -1.5 -0.5 -0.3 Hardness change (IRHD) -1.9 -0.7 -0.2 Leakage (ml) none none none

As shown in Table 2, Examples 1 and 2 according to the present invention can be seen that the secondary crosslinking is unnecessary, so that the overall crosslinking time is greatly shortened, and the heat resistance hardness change from +10 to +6 and +4. It can be seen that all the properties are improved in terms of oil resistance. In addition, in the case of pressure resistance, the improvement in the tightening amount and the hardness change was shown. On the other hand, the comparative example confirmed that the overall physical properties were inferior to the examples.

As described above, the rubber composition for oil seals used in the automatic transmission of the present invention includes a polyacrylate rubber having a pattern viscosity (ML1 + 4, 100 ° C) of 40 to 50 in a rubber matrix, and a particle size of 40 to 40 as a filler. Vulcanization time includes 48 mm carbon black FEF and dry silica with particle size of 7 to 16 nm, resulting in oil seals with improved heat resistance, pressure resistance and oil resistance, as well as the second vulcanization step in the manufacture of oil seals This significantly reduces the productivity and the production cost is significantly reduced. The heat resistance, pressure resistance, oil resistance and compression set are expected to be useful in automatic transmissions and related fields.

Claims (5)

100 weight part of polyacrylate rubbers whose pattern viscosity (ML1 + 4, 100 degreeC) is 40-50; 75 to 85 parts by weight of Fast Extrusion Furnace carbon black having a particle diameter of 40 to 48 mm; And Rubber composition for oil seals used for an automatic transmission, comprising 3 to 10 parts by weight of dry silica. The rubber composition for an oil seal used in an automatic transmission according to claim 1, wherein the dry silica has a particle diameter of 7 to 16 nm. The rubber composition for oil seal used in an automatic transmission according to claim 1, further comprising 5 to 13 parts by weight of a crosslinking agent. The rubber composition for oil seal used in an automatic transmission according to claim 1, further comprising 3 to 10 parts by weight of an antioxidant. Oil seal for use in an automatic transmission, characterized in that produced using the rubber composition of any one of claims 1 to 4.