JP2016216549A - Rubber composition and hose using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a rubber composition excellent in balance between fuel-oil resistance and heat resistance.SOLUTION: A rubber composition contains an acrylonitrile-butadiene rubber, an ethylene acrylic rubber, an alkaline silica and a peroxide vulcanization agent. The acrylonitrile-butadiene rubber and the ethylene acrylic rubber are contained at 65:35 to 85:15 by weight ratio. The content of the alkali silica is 10 pts.wt. to 20 pts.wt. inclusive and the content of the peroxide vulcanization agent is 0.7 pts.wt. to 1.3 pts.wt. inclusive based on total 100 pts.wt. of the acrylonitrile-butadiene rubber and the ethylene acrylic rubber. An inner layer 2 of a hose 1 is manufactured by using the rubber composition.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a hose suitable for fuel transportation and a rubber composition suitable for the hose.

  Fuel transport hoses used in automobiles and the like are required to have various characteristics such as fuel oil resistance (fuel oil deterioration resistance) and heat resistance. Patent Document 1 discloses a fuel hose using an acrylonitrile-butadiene rubber composition having fuel oil resistance.

JP 2005-126583 A

  By the way, when the present inventors conducted an experiment, it was found that the fuel oil resistance and the heat resistance were not kept in a good balance in the hose of Patent Document 1. Moreover, although there is a technical standard defined by the European Economic Commission (abbreviated as ECE) as an evaluation standard for fuel oil resistance and heat resistance, it has been found that the hose of Patent Document 1 does not satisfy this standard.

  Then, an object of this invention is to provide the rubber composition and hose which were excellent in the balance of fuel oil resistance and heat resistance.

The rubber composition of the present invention contains acrylonitrile-butadiene rubber, ethylene acrylic rubber, alkaline silica, and a peroxide vulcanizing agent, and the acrylonitrile-butadiene rubber and the ethylene acrylic rubber have a weight ratio of 65. : 35 to 85:15, the content of the alkaline silica is 10 parts by weight or more and 20 parts by weight or less with respect to 100 parts by weight of the total of the acrylonitrile-butadiene rubber and the ethylene acrylic rubber, and the peroxidation The content of the product vulcanizing agent is 0.7 parts by weight or more and 1.3 parts by weight or less.
Moreover, it is preferable that the hose of this invention has a rubber layer using the said rubber composition.

  Acrylonitrile-butadiene rubber and ethylene acrylic rubber are contained in a predetermined weight ratio and a predetermined amount of alkaline silica is contained, so that the balance between fuel oil resistance and heat resistance is excellent. In addition, when a predetermined amount of the peroxide vulcanizing agent is contained, the balance between fuel oil resistance and heat resistance is further improved while maintaining good tensile characteristics.

  ADVANTAGE OF THE INVENTION According to this invention, the rubber composition and hose excellent in the balance of fuel oil resistance and heat resistance can be provided.

1 is a perspective view of a fuel hose according to an embodiment of the present invention.

  Hereinafter, a preferred embodiment of the present invention will be described with reference to FIG.

〔hose〕
As shown in FIG. 1, the hose 1 is formed by laminating three layers of an inner layer 2, an intermediate layer 3, and an outer layer 4 in order from the inside. The hose 1 is used as a fuel transport hose for an automobile or the like. The fuel passing through the hose 1 directly contacts the inner layer 2 which is the innermost layer. Examples of the fuel include gasoline, alcohol-mixed gasoline (Gasohol), alcohol, liquid petroleum gas (LPG), compressed natural gas (CNG), light oil, dimethyl ether, and the like.

  The inner layer 2 is made of a rubber composition containing acrylonitrile-butadiene rubber, ethylene acrylic rubber, alkaline silica, and a peroxide vulcanizing agent.

  It is known that acrylonitrile-butadiene rubber has fuel oil resistance, and ethylene acrylic rubber has heat resistance. Therefore, it is considered that when these two rubbers are contained, the fuel oil resistance and heat resistance are improved. However, as a result of experiments conducted by the present inventors, it has been found that the fuel oil resistance and the heat resistance cannot be kept in a good balance simply by adjusting the weight ratio of acrylonitrile-butadiene rubber and ethylene acrylic rubber to a suitable range. It was. They also found that they did not meet the technical standards set by the European Economic Commission, which are evaluation standards for fuel oil resistance and heat resistance.

  Therefore, as a result of research, when acrylonitrile-butadiene rubber and ethylene acrylic rubber are contained in a predetermined weight ratio, a predetermined amount of alkaline silica is contained, so that i) fuel oil resistance and heat resistance are balanced. And ii) the knowledge that the technical standards of fuel oil resistance and heat resistance can be cleared. Below, the composition of the rubber composition of this embodiment is demonstrated.

(Acrylonitrile-butadiene rubber)
The acrylonitrile-butadiene rubber preferably has an AN amount (bonded acrylonitrile content) of 31 to 35, more preferably 32.5 to 34.5. As the amount of AN increases, fuel oil resistance and heat resistance are improved, but cold resistance and modulus are liable to decrease. On the other hand, if the amount of AN is small, sufficient fuel oil resistance and heat resistance cannot be obtained.

(Ethylene acrylic rubber)
Examples of the ethylene acrylic rubber include those obtained by copolymerizing ethylene with at least one of alkyl acrylate ester and alkoxyalkyl acrylate ester.

  Acrylonitrile-butadiene rubber and ethylene acrylic rubber are contained in a weight ratio of 65:35 to 85:15. When the weight ratio of acrylonitrile-butadiene rubber is less than 65, the fuel oil resistance is lowered. On the other hand, when the weight ratio of acrylonitrile-butadiene rubber exceeds 85, the heat resistance decreases. Moreover, the extrusion processability at the time of manufacture falls because a viscosity becomes high. Similarly, when the weight ratio of the ethylene acrylic rubber is less than 15, the heat resistance is lowered. On the other hand, when the weight ratio of the ethylene acrylic rubber exceeds 35, the acrylonitrile-butadiene rubber is reduced, so that the fuel oil resistance is lowered. The weight ratio of acrylonitrile-butadiene rubber and ethylene acrylic rubber is more preferably 70:30 to 80:20.

(Alkaline silica)
Examples of the alkaline silica include silica having a hydrogen ion index of 8 or more when it is a dispersion of 10% by weight in pure water among silicas, which is a general term for silicon dioxide or substances composed of silicon dioxide. When alkaline silica is added, a hydroxyl group present on the silica surface and a nitrile group in the acrylonitrile-butadiene rubber molecule or an ester group in the ethylene acrylic rubber molecule form a hydrogen bond, so that acrylonitrile-butadiene rubber and ethylene acrylic rubber It is considered that a rubber composition having a stable degree of vulcanization can be obtained by increasing compatibility and increasing the vulcanization reactivity by making the rubber composition alkaline. Thereby, fuel oil resistance and heat resistance can be maintained with good balance. It can also clear technical standards established by the European Economic Commission. In addition, since acidic silica and neutral silica are more likely to inhibit the vulcanization reaction than alkaline silica, fuel oil resistance, heat resistance, and modulus may be reduced.

  The content of alkaline silica is 10 parts by weight or more and 20 parts by weight or less with respect to 100 parts by weight of the total of acrylonitrile-butadiene rubber and ethylene acrylic rubber. When the content of alkaline silica is less than 10 parts by weight, the fuel oil resistance and heat resistance are lowered, and the modulus is also lowered. On the other hand, when the content of alkaline silica exceeds 20 parts by weight, the extrusion processability at the time of production is lowered due to the increase in viscosity.

  The alkaline silica preferably has a pH of 8 to 12, and more preferably a pH of 10 to 11. When the pH is lower than 8, there is a possibility that the fuel oil resistance, heat resistance and modulus may be reduced due to the decrease in reactivity. On the other hand, if the pH exceeds 12, the alkalinity becomes strong, so that the worker may touch the alkaline silica or the rubber composition at the time of production, and the skin may be drowned, resulting in a safety problem.

(Peroxide vulcanizing agent)
As peroxide vulcanizing agents, benzoyl peroxide, dicumyl peroxide, 2,5-dimethyl-2,5-di (t-butylperoxy) hexane, 1,1′-di-t-butylperoxy-3,3 , 5-trimethylenecyclohexane, 1,3-di- (t-butylperoxy) -diisopropylbenzene, and the like.

  The content of the peroxide vulcanizing agent is preferably 0.7 parts by weight or more and 1.3 parts by weight or less, more preferably 0.8 parts by weight with respect to 100 parts by weight of the total of acrylonitrile-butadiene rubber and ethylene acrylic rubber. It is not less than 1.1 parts by weight. When the content of the peroxide vulcanizing agent is less than 0.7 parts by weight, the modulus is lowered. On the other hand, if the content of the peroxide vulcanizing agent exceeds 1.3 parts by weight, the elongation at break decreases.

  The rubber composition may further contain carbon black, a vulcanization activator, an anti-aging agent, a processing aid, a vulcanization accelerator, a plasticizer, and the like.

  The inner layer 2 of the hose 1 shown in FIG. 1 can be produced as follows, for example. Acrylonitrile-butadiene rubber and ethylene acrylic rubber are blended in the above weight ratio, and the aforementioned predetermined amounts of alkaline silica and peroxide vulcanizing agent are blended and kneaded. The obtained rubber composition is formed into a cylindrical shape by extrusion molding or the like and then vulcanized to obtain the inner layer 2.

  As described above, the rubber composition of the present embodiment contains acrylonitrile-butadiene rubber and ethylene acrylic rubber in a predetermined weight ratio, and contains a predetermined amount of alkaline silica, so that the fuel oil resistance and heat resistance are increased. It will be excellent in balance with nature. When this rubber composition is used for the inner layer 2 of the hose 1, the inner layer 2 is excellent in balance between fuel oil resistance and heat resistance, so that deterioration of the inner layer 2 can be significantly suppressed.

  Moreover, since the rubber composition of this embodiment contains a predetermined amount of the peroxide vulcanizing agent, it has excellent fuel oil resistance and heat resistance while maintaining good tensile properties. Therefore, the inner layer 2 has good tensile properties and is hardly deteriorated. Therefore, the life of the hose 1 can be extended.

  Each characteristic when the composition of the rubber composition was changed was examined. Table 1 shows each compounding and each characteristic of the rubber composition.

Each material shown in Table 1 will be described.
Nipol 1052J (manufactured by Nippon Zeon Co., Ltd.) was used as the acrylonitrile-butadiene rubber, and Vamac DP (manufactured by DuPont) was used as the ethylene acrylic rubber.
As the carbon black, FEF (manufactured by Tokai Carbon Co., Ltd.) was used.
As a white filler, “HI-SIL 233” (manufactured by PPG Industrial Co., Ltd. (registered trademark)) was used as neutral silica. “HI-SIL 233” has a pH of 6.9. Further, “Carplex 1120” (manufactured by DSL Japan) was used as alkaline silica. “Carplex 1120” has a pH of 11.0.
As the vulcanization activator, “Zinc oxide three types” (manufactured by Shodo Chemical Industry Co., Ltd.) was used.
As an anti-aging agent, “NOCRACK CD” (manufactured by Ouchi Shinsei Chemical Industry Co., Ltd.) and “NOCRACK MB” (manufactured by Ouchi Shinsei Chemical Industrial Co., Ltd.) were used.
“Stearic acid 50S” (manufactured by Shin Nippon Chemical Co., Ltd.) was used as a processing aid.
“Perbutyl P” (manufactured by NOF Corporation (registered trademark)) was used as a vulcanizing agent (peroxide vulcanizing agent).

A rubber composition kneaded according to the formulation shown in Table 1 was formed into a sheet shape and subjected to vulcanization treatment to produce a vulcanized rubber (press sheet) for testing. Each characteristic of the press sheet was examined as follows.
1. Uncured rubber before unvulcanized physical vulcanization treatment, Mooney viscosity after preheating time of 1 minute at a temperature of 100 ° C. and rotor rotation time of 4 minutes using an L-shaped rotor in accordance with JIS K6300-1. Was measured. Based on the experience so far, when Mooney viscosity was 89 or less, it was judged that the processability such as extrusion was good, and when it was 90 or more, there was a problem in processability.
2. Tensile properties The following test was performed on the press sheet after vulcanization.
(TSb: Tensile strength at cutting)
It formed in the dumbbell-shaped test piece (type 3), and measured the tensile strength at the time of cutting according to JIS K6251. Based on the experience so far, when the tensile strength at the time of cutting is 10.0 MPa or more, it has sufficient strength, and when it is 9.9 MPa or less, it does not have sufficient strength. It was judged.
(Eb: Elongation at cutting)
It formed in the dumbbell-shaped test piece (type 3), and measured the elongation at the time of cutting according to JIS K6251. Based on the experience so far, when the elongation at break was 250% or more, it was judged to have sufficient elongation, and when it was 240% or less, it was judged not to have sufficient elongation.
(M100: 100% modulus)
A dumbbell-shaped test piece (No. 3) was formed, and 100% modulus (100% elongation tensile stress) was measured according to JIS K6251. Based on the experience so far, it was judged that when the 100% modulus was 3.3 MPa or more, it had sufficient stress, and when it was 3.2 MPa or less, it did not have sufficient stress.
3. Heat resistance (heat aging resistance)
(TSb: Tensile strength at cutting)
The rate of change in tensile strength after 336 hours after the passage of 24 hours at a temperature of 115 ° C. was measured in accordance with Regulation 110 (ECE R110 Class 2 Annex 4B 2.3.1.3) established by the European Economic Commission. From Rule 110, when the rate of change was within 35%, it was determined that the product had sufficient heat resistance. On the other hand, when the rate of change was 36% or more, it was determined that the heat resistance was not sufficient.
(Eb: Elongation at cutting)
The rate of change in elongation at break after 336 hours after lapse of 24 hours at a temperature of 115 ° C. was measured in accordance with Regulation 110 (ECE R110 Class 2 Annex 4B 2.3.1.3) established by the European Economic Commission. From Rule 110, when the rate of change was within -25%, it was determined that the product had sufficient heat resistance. On the other hand, when it was -26% or less, it was judged that it did not have sufficient heat resistance.
Then, by combining the results of TSb and Eb, when the change rate of TSb is within 35% and the change rate of Eb is within -25%, it is judged that the heat resistance is sufficient, It was judged that it did not have sufficient heat resistance.
4. Fuel oil resistance (n-pentane resistance)
(TSb: Tensile strength at cutting)
The rate of change in tensile strength after 72 hours at a temperature of 23 ° C. was measured in accordance with Regulation 110 (ECE R110 Class 2 Annex 4B 2.3.1.3) established by the European Economic Commission. From Rule 110, when the rate of change was within -25%, it was judged to have fuel oil resistance. On the other hand, when the rate of change was −26% or less, it was determined that the fuel oil resistance was not sufficient.
(Eb: Elongation at cutting)
The rate of change in elongation after 72 hours at a temperature of 23 ° C. was measured in accordance with Regulation 110 (ECE R110 Class 2 Annex 4B 2.3.1.3) established by the European Economic Commission. From Rule 110, it was determined that the fuel oil resistance was sufficient when the rate of change was within -30%. On the other hand, when the rate of change was −31% or less, it was judged that the fuel oil resistance was not sufficient.
Then, by combining the results of TSb and Eb, when the change rate of TSb is within -25% and the change rate of Eb is within -30%, it is determined that the fuel oil resistance is sufficient. Other than that, it was judged that the fuel oil resistance was not sufficient.

  From Table 1, in Examples 1-8, since acrylonitrile-butadiene rubber and ethylene acrylic rubber are contained in a predetermined weight ratio and a predetermined amount of alkaline silica is contained, the heat resistance and fuel oil resistance are Excellent balance. In addition, a rubber composition satisfying the technical standards set by the European Economic Commission, which is an evaluation standard for fuel oil resistance and heat resistance, was obtained. Further, in Examples 1 to 8, since a predetermined amount of the peroxide vulcanizing agent was contained, tensile properties such as elongation at break and 100% modulus were good.

  On the other hand, in Comparative Examples 1-7, since the content of acrylonitrile-butadiene rubber, ethylene acrylic rubber, and alkaline silica was not a predetermined amount, there was a problem in the balance between heat resistance and fuel oil resistance. There were also problems with unvulcanized physical properties and modulus. Furthermore, in Comparative Examples 8 and 9, since the content of the peroxide vulcanizing agent was not a predetermined amount, there was a problem in the modulus and elongation at break.

When Examples 1 and 2 and Comparative Examples 1 to 4 are compared, acrylonitrile-butadiene rubber and ethylene acrylic rubber have the same weight ratio, but the content of alkaline silica is different.
In Comparative Example 1, there was a problem in heat resistance and fuel oil resistance when 20% by weight of neutral silica was contained without using alkaline silica. From Comparative Example 1, it was found that neutral silica cannot improve heat resistance and fuel oil resistance.
In Comparative Example 2, since no silica was used, there was a problem in heat resistance and fuel oil resistance. From Comparative Example 2, it was found that heat resistance and fuel oil resistance could not be maintained in a good balance only by adjusting the weight ratio of acrylonitrile-butadiene rubber and ethylene acrylic rubber. It was also found that it does not meet the technical standards for heat resistance and fuel oil resistance established by the European Economic Commission.
In Comparative Example 3, alkaline silica was used, but there was a problem in fuel oil resistance because the content of alkaline silica was too small.
Moreover, since the modulus was lowered in Comparative Examples 2 and 3, it was found that if the content of alkaline silica is small, the tensile properties are also affected.
On the other hand, in Comparative Example 4, when alkaline silica was adjusted to 30% by weight, there was no problem in heat resistance and fuel oil resistance, but unvulcanized physical properties were lowered. From Comparative Example 4, it was found that when there is a large amount of alkaline silica, the balance between heat resistance and fuel oil resistance can be improved, but unvulcanized physical properties required as a rubber composition cannot be ensured.

Examples 1, 3 to 5 and Comparative Examples 5 to 7 have the same content of alkaline silica, but differ in the weight ratio of acrylonitrile-butadiene rubber and ethylene acrylic rubber.
When these were compared, in Comparative Examples 5 and 6, since there were many acrylonitrile-butadiene rubbers and there were few ethylene acrylic rubbers, it turned out that there exists a problem in heat resistance. In Comparative Example 5, only acrylonitrile-butadiene rubber having a high viscosity was used, and ethylene acrylic rubber having a low viscosity was not used. Therefore, the rubber composition was not plasticized, and there was a problem with unvulcanized physical properties. .
In Comparative Example 7, there was a problem in fuel oil resistance because there was little acrylonitrile-butadiene rubber and much ethylene acrylic rubber.

Further, Examples 1, 6 to 8 and Comparative Examples 8 and 9 have the same weight ratio of acrylonitrile-butadiene rubber and ethylene acrylic rubber and the same content of alkaline silica. The agent content is different.
When these were compared, in Comparative Example 8 where the amount of the peroxide vulcanizing agent was small, the modulus was lowered and there was a problem in tensile properties.
Further, in Comparative Example 9 having a large amount of peroxide vulcanizing agent, the elongation at break was lowered, and there was a problem in tensile properties.

  As mentioned above, although embodiment of this invention was described based on drawing, it should be thought that a specific structure is not limited to these embodiment. The scope of the present invention is shown not by the above description but by the scope of claims, and includes all modifications within the meaning and scope equivalent to the scope of claims.

  The rubber composition and hose of the present invention can be used not only for automobiles but also for fuel transportation hoses other than automobiles.

1 Hose 2 Inner layer 3 Middle layer 4 Outer layer

Claims (2)

Containing acrylonitrile-butadiene rubber, ethylene acrylic rubber, alkaline silica, and peroxide vulcanizing agent,
The acrylonitrile-butadiene rubber and the ethylene acrylic rubber are contained in a weight ratio of 65:35 to 85:15,
The content of the alkaline silica is 10 to 20 parts by weight with respect to a total of 100 parts by weight of the acrylonitrile-butadiene rubber and the ethylene acrylic rubber, and the content of the peroxide vulcanizing agent is 0.00. A rubber composition characterized by being 7 parts by weight or more and 1.3 parts by weight or less.   A hose comprising a rubber layer using the rubber composition according to claim 1.

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