Ethylene propylene acrylate rubber composition for automobile engine and method for producing the same

Abstract

The application discloses an ethylene propylene acrylate rubber composition for automobile engine, which is made of raw materials including the following components in parts by weight: 85-95 parts of ethylene propylene acrylate rubber, 5-15 parts of acrylate rubber, 1-2 parts of stearic acid, 1-3 parts of antioxidant, 10-20 parts of plasticizer, 50-80 parts of carbon black, 1.5-2.5 parts of vulcanizing agent, 2-5 parts of accelerator, and 1.5-3 parts of internal release agent. Compared with traditional acrylate mixing rubber, the composition has relatively higher elongation at break, tear resistance, high-temperature compression set resistance, oil resistance and aging resistance, can meet the strict index requirements of high-end vehicles and is suitable for specific use environment. The application further discloses application of the ethylene propylene acrylate rubber composition for automobile engine in preparation of automobile engine cooling hose.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of rubber composite processing and the field of automobile engine cooling system, and relates to an ethylene acrylate rubber composition for automobile engine and a preparation method thereof, in particular to a rubber compound for preparing an automobile engine oil cooling hose, especially to a rubber compound for preparing inner and outer rubber layers of an automobile engine oil cooling hose, and an automobile engine oil cooling hose prepared from the above rubber compound. BACKGROUND

[0002] With the increasingly compact structure of automobiles and the rapid improvement of performance requirements, the ambient temperature around the automobile engine is also increasing, and the requirements for elastomers in the automobile industry are constantly changing. In particular, high-end vehicles have strict index requirements for the temperature resistance and oil resistance of rubber pipelines. In particular, the temperature resistance level has been improved from the original 150 DEG C to 175 DEG C. Ordinary rubber elastomers are difficult to work in this temperature environment, especially it is more difficult to meet the higher requirements of oil resistance, pressure change, tear resistance and other properties.

[0003] In order to solve such problems, it is necessary to develop new elastomer formulations that can meet the requirements in terms of mechanical properties, heat resistance, oil resistance, pressure change and other technical aspects, while having good extrusion processability, vulcanization processability and other requirements in actual production and application. SUMMARY

[0004] The purpose of the present application is to provide an ethylene acrylate rubber composition for automobile engine, which has excellent compression resistance, tear resistance, aging resistance and oil resistance, and can meet the stringent index requirements of high-end vehicles to adapt to specific use environment conditions.

[0005] The purpose of the present application is achieved by the following technical solutions:

[0006] An ethylene acrylate rubber composition for automobile engine, which is made of raw materials including the following weight fractions: 85-95 parts of ethylene acrylate rubber, 5-15 parts of acrylate rubber, 1-2 parts of stearic acid, 1-3 parts of antioxidant, 10-20 parts of plasticizer, 50-80 parts of carbon black, 1.5-2.5 parts of vulcanizing agent, 2-5 parts of accelerator, 1.5-3 parts of internal release agent; the total amount of ethylene acrylate rubber and acrylate rubber is 100 parts.

[0007] The ethylene acrylate rubber is one of . The methacrylate content of the ethylene acrylate rubber is relatively higher, and has better oil resistance.

[0008] The acrylic ester rubber is a carboxyl type acrylic ester rubber; specifically, the acrylic ester rubber is PA-526.

[0009] The weight ratio of the ethylene acrylic ester rubber and the acrylic ester rubber is 17:3-19:1.

[0010] The anti-aging agent is 4,4'-di(phenyl isopropyl) diphenylamine (NAUGARD 445).

[0011] The plasticizer is trioctyl trimellitate (TOTM).

[0012] The carbon black is at least one of carbon black N550 and carbon black N774, preferably a combination of carbon black N550 and carbon black N774 in a weight ratio of 1:2-3:4.

[0013] The vulcanizing agent is HMDC-70, which is hexamethylene diamine carbamate salt with AEM as a carrier.

[0014] The accelerator is VULACE ACT-500, which is an organic amine derivative with amorphous silicon oxide as a carrier.

[0015] The internal release agent is at least one of complex organic alkyl acid phosphate Vanfre VAM and octadecylamine Armeen 18D, preferably a combination of Vanfre VAM and Armeen 18D in a weight ratio of 1:0.5-1:1.5.

[0016] Another object of the present application is to provide a preparation method of the ethylene acrylic ester rubber composition for automobile engine.

[0017] Step (1), water cooling of the internal mixer, the cooling water temperature is not higher than 15℃, the working chamber temperature of the internal mixer is controlled to be not more than 50℃, the ethylene acrylic ester rubber and the acrylic ester rubber are mixed for 20-40s, then the stearic acid, the anti-aging agent and the internal release agent are added and mixed for 30-60s, the carbon black and the plasticizer are added to the mixture and continue to mix, when the temperature of the mixture in the internal mixer increases to 85-90℃, the vulcanizing agent and the accelerator are added and continue to mix, when the temperature of the internal mixer increases to 100-105℃, the rubber is discharged, and the rubber is moved to an open mill for thin passing and sheeting, and cooled to room temperature, and then placed and stabilized for 8 hours;

[0018] Step (2), the ethylene-acrylate rubber composition material obtained in step (1) is placed in a flat vulcanization machine for primary vulcanization, the primary vulcanization temperature is 170-175℃, the primary vulcanization time is 5-15min, then the composition material is placed in an oven for secondary vulcanization, the secondary vulcanization temperature is 170-180℃, the secondary vulcanization time is 3-6h, and the ethylene-acrylate rubber composition is obtained.

[0019] In step (1), after the carbon black and the plasticizer are added, the mixture is generally mixed for 2-3min, and the temperature of the mixture in the internal mixer is increased to 85-90℃.

[0020] Another object of the present application is to provide the use of the ethylene-acrylate rubber composition for automobile engine in the preparation of automobile engine cooling hose.

[0021] An automobile engine cooling hose is made of the ethylene-acrylate rubber composition for automobile engine as the rubber material of the inner and outer layers of the hose.

[0022] The present application has the following advantages:

[0023] The ethylene-acrylate rubber has good aging resistance, tensile property and low temperature resistance, but poor oil resistance, and cannot meet the strict oil resistance requirements of products when used alone. The raw rubber material of the composition of the present application uses ethylene-acrylate rubber and acrylate rubber in combination, so that the oil resistance of the rubber material can be considered.

[0024] The hexamethylene diamine carbamate salt using AEM as the carrier is used as the vulcanizing agent, which effectively improves the mixing effect of the mixture, shortens the mixing cycle, and overcomes the defects of the traditional 1# vulcanizing agent, such as uneven dispersion in AEM, formation of bubbles or pores, and easy appearance of white spots. The organic amine derivative VULACE ACT-500 using amorphous silicon oxide as the carrier is used to activate the reaction between the acidic groups in the rubber matrix and the diamines in the vulcanizing agent, accelerate the crosslinking reaction, and improve the crosslinking efficiency. Compared with the traditional accelerator DOTG, the mixed rubber can obtain higher crosslinking density and elastic modulus, and the aging resistance is also significantly improved. The aromatic ester plasticizer TOTM is used. Since only the strong polar ester group exists in TOTM, compared with the TP-759 type plasticizer similar to the mixture of polyether and polyester, the interaction between TOTM and the mixed rubber is stronger, so that the physical properties of the vulcanized rubber are better. Moreover, TOTM contains a rigid benzene ring structure with a large volume, so the structure of the vulcanized rubber is more stable, and the compression permanent set is smaller. At the same time, in order to consider the elongation, tear resistance, compression resistance and processing performance of the mixed rubber, the carbon black N550 with excellent process and reinforcing comprehensive performance is used in combination with the carbon black N774 with large particle size and less combined rubber with rubber, so that the mixed rubber with excellent comprehensive properties is obtained.

[0025] Compared with the conventional acrylate compound, the composition of the application has relatively higher elongation at break, tear resistance, high temperature compression set resistance, oil resistance and aging resistance, and can meet the stringent index requirements of high-end vehicles to adapt to specific use environment conditions. DETAILED DESCRIPTION

[0026] The technical solutions of the application are further described below through specific embodiments.

[0027] Table 1. Rubber composition formulation of examples 1-3 and comparative examples 1-4 (parts by weight)

[0028]

[0029] Example 1

[0030] An ethylene acrylate rubber composition for automobile engine, the raw materials and parts by weight are shown in Table 1, and is prepared according to the following preparation method:

[0031] Step (1), the internal mixer is cooled by water, the cooling water temperature is not higher than 15℃, the working chamber temperature of the internal mixer is controlled not to exceed 50℃, the ethylene acrylate rubber and the acrylate rubber are mixed first for 20s, then the stearic acid, the antioxidant NAUGARD445 and the internal release agent Vanfre VAM, Armeen 18D are mixed for 1min, the carbon black N774, the carbon black N550 and the plasticizer TOTM are added to the above mixture and continue to mix, when the temperature of the mixture in the internal mixer increases to 90℃, the vulcanizing agent HMDC-70 and the accelerator VULACE ACT-500 are added and continue to mix, when the temperature of the internal mixer rises to 105℃, the rubber is discharged, moved to the open mill for thin pass-out sheet, cooled to room temperature and placed for 8 hours to obtain the ethylene acrylate rubber composition material;

[0032] Step (2), the ethylene acrylate rubber composition material is placed in a flat vulcanizing machine for one-stage vulcanization, the one-stage vulcanization temperature is 175℃, the vulcanization time is 15min, then the composition material is placed in an oven for two-stage vulcanization, the two-stage vulcanization temperature is 175℃, the vulcanization time is 4h, and the ethylene acrylate rubber composition is obtained.

[0033] Example 2

[0034] The raw materials are weighed according to Table 1, and the rubber is prepared according to the preparation method of Example 1.

[0035] Example 3

[0036] The raw materials are weighed according to Table 1, and the rubber is prepared according to the preparation method of Example 1.

[0037] Comparative Example 1

[0038] The raw materials were weighed according to Table 1, and the adhesive was prepared according to the preparation method of Example 1.

[0039] Comparative Example 2

[0040] The raw materials were weighed according to Table 1, and the adhesive was prepared according to the preparation method of Example 1.

[0041] Comparative Example 3

[0042] The raw materials were weighed according to Table 1, and the adhesive was prepared according to the preparation method of Example 1.

[0043] Comparative Example 4

[0044] The raw materials were weighed according to Table 1, and the adhesive was prepared according to the preparation method of Example 1.

[0045] The properties of the rubber compounds prepared in Examples 1-3 and Comparative Examples 1-4 were examined, and the results are shown in Table 2.

[0046] Table 2. Performance parameters of the rubber compositions of Examples 1-3 and Comparative Examples 1-3

[0047]

[0048]

[0049] It can be seen that neither ethylene acrylate rubber (AEM) nor acrylate rubber (ACM) alone can fully meet the performance requirements of the rubber compositions. Specifically, rubber compositions using ethylene acrylate rubber alone fail to meet the oil resistance requirements, while compositions using acrylate rubber alone exhibit excellent oil resistance but show significant decreases in heat aging performance, tear strength, and compression set resistance. When ethylene acrylate rubber and acrylate rubber are used in combination in a total of 100 parts by weight, the tear performance of the rubber composition fails to meet the requirements when the acrylate rubber content increases to 20 parts by weight. This is mainly due to the inherent structures of the two rubbers; ethylene acrylate rubber has superior elasticity and mechanical properties compared to acrylate rubber, but AEM has a higher acrylate content, resulting in poorer resistance to swelling with polar IRM 903 standard oil. Therefore, it needs to be used in combination with acrylate rubber to improve the oil resistance of the mixture. Compared to acrylate rubber, ethylene acrylate rubber has a higher elastic modulus; increasing the amount of AEM can improve the compression set properties of the blend. The rubber composition of this invention possesses excellent conventional physical properties, long-term aging resistance at 175°C, tear resistance, compression set, and oil resistance, meeting the technical requirements of high-end vehicle models currently on the market.

Claims

1. An ethylene acrylate rubber composition for automotive engines, characterized in that: This rubber composition is made from the following raw materials in parts by weight: 85-95 parts ethylene acrylate rubber, 5-15 parts acrylate rubber, 1-2 parts stearic acid, 1-3 parts antioxidant, 10-20 parts plasticizer, 50-80 parts carbon black, 1.5-2.5 parts vulcanizing agent, 2-5 parts accelerator, and 1.5-3 parts internal release agent; wherein the ethylene acrylate rubber is one of Vamac® GLS and Vamac® Ultra LS; wherein the acrylate rubber is a carboxyl-type acrylate rubber; wherein the plasticizer is TOTM; wherein the carbon black is a combination of carbon black N550 and carbon black N774 in a weight ratio of 1:2 to 3:4; wherein the vulcanizing agent is HMDC-70; and wherein the accelerator is VULACEACT-500.

2. The ethylene acrylate rubber composition for automotive engines according to claim 1, characterized in that: The antioxidant mentioned is NAUGARD 445.

3. The ethylene acrylate rubber composition for automotive engines according to claim 1, characterized in that: The internal release agent is at least one of Vanfre VAM and Armeen 18D.

4. The ethylene acrylate rubber composition for automotive engines according to claim 3, characterized in that: The internal release agent is a combination of Vanfre VAM and Armeen 18D in a weight ratio of 1:0.5 to 1:1.

5.

5. A method for preparing the ethylene acrylate rubber composition for automotive engines according to claim 1, characterized in that: Includes the following steps: Step (1): Cool the internal mixer with water. The temperature of the cooling water should not exceed 15°C. Control the temperature of the internal mixer chamber to not exceed 50°C. First, mix the ethylene acrylate rubber and acrylate rubber for 20-40 seconds. Then, add stearic acid, antioxidant and internal release agent and mix for 30-60 seconds. Add carbon black and plasticizer to the above mixture and continue mixing. When the temperature of the mixture in the internal mixer increases to 85-90°C, add vulcanizing agent and accelerator and continue mixing. When the temperature of the internal mixer rises to 100-105°C, discharge the rubber and transfer it to an open rubber mixing mill for thin sheeting. Cool to room temperature and let it stand for 8 hours to stabilize. Step (2): Place the ethylene acrylate rubber composition material obtained in step (1) into a flat vulcanizing machine for a first-stage vulcanization at a temperature of 170-175°C for 5-15 minutes. Then place the composition material into an oven for a second-stage vulcanization at a temperature of 170-180°C for 3-6 hours to obtain the ethylene acrylate rubber composition.

6. The application of the ethylene acrylate rubber composition for automotive engines according to claim 1 in the preparation of automotive engine oil cooler pipes.

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