JPH05262914A - Rubber composition and transmission belt made thereof - Google Patents

Abstract

PURPOSE:To obtain a composition giving a transmission belt having excellent abrasion resistance, flexural fatigue resistance, etc., by adding carbon black and a plasticizer to a mixture of a hydrogenated rubber and an unsaturated carboxylic acid metal salt. CONSTITUTION:The objective composition is produced by compounding (A) 100 pts.wt. of a hydrogenated rubber consisting of a copolymer of an ethylenic unsaturated nitrile and a conjugated diene with (B) 10-100 pts.wt. of an unsaturated carboxylic acid metal salt, (C) 0.2-10 pts.wt. of an organic peroxide, (D) 10-35 pts.wt. of carbon black and (E) 10-30 pts.wt. of a plasticizer. The composition can be used as a material for a transmission belt for automobile, etc.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rubber composition capable of imparting excellent strength characteristics and fatigue characteristics, and a power transmission belt using the rubber composition.

[0002]

2. Description of the Related Art Conventionally, for example, in a drive belt for driving an auxiliary machine, reinforcing fibers are mixed with upper rubber, lower rubber or rib rubber by mixing short fibers or carbon black.

On the other hand, in the case of power transmission belts for automobiles, on the other hand, the so-called maintenance-free requirement has led to a demand for a longer life than ever before. In order to meet such demands, for example, Japanese Patent Laid-Open No. 1-311158 discloses that the physical properties of a vulcanizable rubber composition constituting a tooth rubber layer and a back rubber layer of a toothed belt are modified. As disclosed, by mixing zinc methacrylate and an organic peroxide into a hydrogenated rubber composed of an ethylenically unsaturated nitrile-conjugated diene copolymer, it is possible to improve flex fatigue resistance and abrasion resistance. The one that is designed is proposed.

[0004]

However, when, for example, a V-ribbed belt is made of the above rubber composition containing short fibers, it is possible to improve abrasion resistance, lateral pressure resistance, stabilization of abrasion coefficient and the like. The flex fatigue resistance decreases.

When a V-ribbed belt is made of a rubber composition in which carbon black is mixed with a commonly used rubber (for example, chloroprene rubber), abrasion resistance is improved, but bending fatigue resistance is excessively mixed. Since it decreases, there is an upper limit to the amount of carbon black mixed.

On the other hand, a mixture of hydrogenated rubber with zinc methacrylate or the like can improve bending fatigue resistance and abrasion resistance as described above, but is required to withstand use under severe conditions. Further excellent strength characteristics and fatigue characteristics are required. Further, this is reinforcement by a chemical reaction with an unsaturated carboxylic acid metal salt such as zinc methacrylate, and mixing carbon black into this as described above would rather reduce the rubber strength. It was said that the mixing of carbon black was unnecessary.

The present invention has been made in view of the above points, and an object thereof is to mix carbon black, which has been heretofore unnecessary, into a mixture of hydrogenated rubber and a metal salt of an unsaturated carboxylic acid. Another object of the present invention is to provide a rubber composition having excellent properties such as abrasion resistance and bending fatigue resistance, and a transmission belt using the same by adding a plasticizer together with the rubber composition.

[0008]

In order to achieve the above object, a first solution of the present invention is to provide a rubber composition containing a hydrogenated rubber comprising an ethylenically unsaturated nitrile-conjugated diene copolymer. 100 parts by weight, unsaturated carboxylic acid metal salt; 1
0 to 100 parts by weight, organic peroxide; 0.2 to 10 parts by weight, carbon black; 10 to 35 parts by weight and a plasticizer, 10 to 30 parts by weight.

The second solution of the present invention is to provide a hydrogenated rubber comprising an ethylenically unsaturated nitrile-conjugated diene copolymer, 100 parts by weight, an unsaturated carboxylic acid metal salt;
00 parts by weight, organic peroxide; 0.2-10 parts by weight, carbon black; 10-35 parts by weight and plasticizer; 10-
That is, the rubber composition containing 30 parts by weight was used for at least a part of the rubber portion constituting the belt.

[0010]

With the above constitution, in the first and second means of the present invention, the rubber composition is a hydrogenated rubber comprising an ethylenically unsaturated nitrile-conjugated diene copolymer; 100 parts by weight; 100 parts by weight, organic peroxide; 0.2-
10 parts by weight, carbon black; 10 to 35 parts by weight, and a plasticizer; 10 to 30 parts by weight,
Since at least a part of the belt-constituting rubber portion of the power transmission belt is constituted by this rubber composition, the reinforcement by the chemical reaction between the hydrogenated rubber and the unsaturated carboxylic acid metal salt and the physical reinforcement by the carbon black are in phase with each other. It is possible to obtain a power transmission belt having further excellent characteristics such as abrasion resistance and bending fatigue resistance.

[0011]

EXAMPLES A rubber composition according to an example of the present invention and a transmission belt using the same will be described below.

First, the rubber composition according to the first embodiment of the present invention will be described. This rubber composition comprises a hydrogenated rubber comprising an ethylenically unsaturated nitrile-conjugated diene copolymer; 100 parts by weight, Unsaturated carboxylic acid metal salt; 10
100 parts by weight, organic peroxide; 0.2-10 parts by weight and carbon black; 10-35 parts by weight and plasticizer;
It is configured to contain 10 to 30 parts by weight.

A hydrogenated rubber comprising an ethylenically unsaturated nitrile-conjugated diene copolymer is an ethylenically unsaturated nitrile such as acrylonitrile or methacrylonitrile.
A rubber obtained by adding hydrogen to a copolymer of a conjugated diene such as 1,3-butadiene, isoprene, and 1,3-pentadiene to saturate the double bond present in the conjugated diene monomer unit. That is. For example, hydrogenated acrylonitrile butadiene rubber (hereinafter abbreviated as H-NBR) obtained by hydrogenating a copolymer of acrylonitrile and 1,3-butadiene can be mentioned. Taking this as an example, H-NB
The ratio of acrylonitrile rubber monomer unit in R is 1
0 to 60% by weight, and the ratio of conjugated diene monomer units is set to 30% by weight or less by means of partial hydrogenation or the like. Also, H-
The molecular weight, glass transition temperature, hydrogenation rate and the like of NBR are not particularly limited, but usually, the hydrogenation rate of the double bond of the conjugated diene monomer unit is 10 to 99%, preferably 80.
~ 95% is good.

The unsaturated carboxylic acid metal salt is an ionic bond between an unsaturated carboxylic acid having a carboxyl group and a metal, and is preferably zinc acrylate or zinc methacrylate. The content of this unsaturated carboxylic acid metal salt is set to 10 to 100 parts by weight with respect to 100 parts by weight of hydrogenated rubber, and the effects as expected below 10 parts by weight and above 100 parts by weight are obtained. Because you cannot do it. Further, the ratio of the hydrogenated rubber to the unsaturated carboxylic acid metal salt is preferably set to 100/100 ≧ hydrogenated rubber / unsaturated carboxylic acid metal salt ≧ 100/25. The reason for setting such a range is that if it is less than 100/25, the strength properties are poor, whereas if it exceeds 100/100, the bending fatigue resistance and impact resilience are poor, and the hardness increase is large.

The organic peroxide is used as a cross-linking agent for hydrogenated rubber. Examples thereof include benzoyl peroxide, lauroyl peroxide, ditertiary butyl peroxide, acetyl peroxide, tert-butyl peroxybenzoic acid and dicumyl peroxide. , Peroxybenzoic acid, tertiary butyl peroxypivalate and azobisisobutyronitrile are preferred. These organic peroxides may be used alone or in combination. The content of this organic peroxide is set to 0.2 to 10 parts by weight with respect to 100 parts by weight of hydrogenated rubber. This is because if it exceeds the range, sufficient rubber elasticity and flex fatigue resistance cannot be obtained.

Carbon black is used as a reinforcing agent, for example, SRF, GPF, FF and FE.
Furnace black such as F, HPC, MPC and EP
Channel blacks such as C, thermal blacks such as FT and MT, and the like are mentioned, and furnace blacks such as SRF and FEF are particularly preferable. The content of this carbon black is hydrogenated rubber; 10 to 3 relative to 100 parts by weight.
The reason why the amount is set to 5 parts by weight is that if the amount is less than 10 parts by weight or more than 35 parts by weight, the desired effects in terms of wear resistance and bending fatigue resistance cannot be obtained.

The plasticizer is used for imparting plasticity to the rubber and increasing flexibility, and includes, for example, trimellitic acid type, polyester type, polyether type and phthalic acid type excellent heat resistance. A plasticizer, preferably a trimellitic acid-based or polyester-based plasticizer. The content of the plasticizer is set to 10 to 30 parts by weight with respect to 100 parts by weight of hydrogenated rubber, because the effect less than 10 parts by weight and the amount exceeding 30 parts by weight are as expected from the relationship with carbon black Because you will not be able to get. Further, if the content of the plasticizer is more than 30 parts by weight, the strength is remarkably reduced, and the belt may bleed due to running.

In the vulcanizable rubber composition of the present invention, a reinforcing agent such as silica, a filler such as calcium carbonate and talc, a cross-linking agent such as sulfur, a cross-linking aid, and a vulcanization accelerator together with the above components. , Plasticizers, stabilizers, processing aids, anti-aging agents, colorants, and the like, various chemicals ordinarily used in the rubber industry are appropriately blended according to the purpose of use.

Next, a V-ribbed belt A as a transmission belt using the rubber composition as described above will be described with reference to FIG.

The V-ribbed belt A comprises an adhesive rubber layer 2 in which a plurality of tensile members 1, 1, ... Are embedded. A rubber-coated canvas 3 is provided on the upper surface of the adhesive rubber layer 2 and a lower surface is provided on the lower surface. Rib rubber layers 5 each having three ribs 4, 4, 4 are integrally formed. The rib rubber layer 5 is composed of the rubber composition as described above.

Next, the test results of the V-ribbed belt A according to one embodiment of the present invention are shown in Table 1 together with comparative examples.

[0022]

[Table 1]

As a result, in the examples of the present invention in which both carbon black and the plasticizer were mixed, the wear resistance was
It is possible to maintain a level equal to or higher than that of Comparative Example 1 in which short fibers are mixed with hydrogenated rubber (methacrylic acid type), and to significantly improve the bending fatigue resistance. Further, in the examples of the present invention, since the heat resistance is excellent as compared with Comparative Examples 2 and 3 in which the matrix is chloroprene rubber, the bending fatigue resistance at high temperature is also excellent. Further, in the present invention example, a highly elastic rubber vulcanizate is obtained by reinforcement with zinc methacrylate as compared with ordinary carbon black reinforcement, and flex fatigue resistance is also superior to that of ordinary carbon black reinforcement. is there. Further, in the example of the present invention, since the short fibers are not mixed, the grinding step in the belt manufacturing process can be omitted, which is advantageous in manufacturing cost.

Further, a V-ribbed belt A and a toothed belt A'as transmission belts were produced using the rubber composition as described above. Since the V-ribbed belt A is the same as the above-mentioned embodiment, the description thereof will be omitted, and the toothed belt A ′ will be described based on FIG.

The toothed belt A'comprises a back rubber layer 7 in which a plurality of (only one in FIG. 2) core yarns 6, 6, ... Are integrally formed with a plurality of tooth rubber layers 8, 8, ...
A tooth cloth 9 is integrally bonded to the tooth surfaces of 8, ... With an adhesive (not shown). The tooth rubber layers 8, 8, ... Are composed of the rubber composition as described above.

Next, the test results of the V-ribbed belt A and the toothed belt A'according to another embodiment of the present invention are shown in Table 2 together with the rubber composition and the physical properties of the vulcanized rubber.

[0027]

[Table 2]

As a result, in the examples of the present invention in which both the carbon black and the plasticizer were mixed, the bending fatigue resistance and abrasion resistance were remarkably improved. However, in Comparative Example 4 in which only carbon black is mixed and in Comparative Example 3 in which only a plasticizer is mixed, the bending fatigue resistance and the wear resistance are equal to or more than those of Comparative Example 2 in which neither carbon black nor plasticizer is mixed. It was less than that. Particularly, in the example of the present invention,
Regarding the flex fatigue resistance, it exhibited a remarkable effect under a temperature-sensitive (120 ° C) condition.

In each of the above examples, the rubber composition of the present invention is applied to the rib rubber layer 5 of the V-ribbed belt A and the tooth rubber layer 8 of the toothed belt A ', respectively. Is also applicable to upper rubber and lower rubber.

In each of the above embodiments, the transmission belt is V
Although the ribbed belt A and the toothed belt A ′ are shown, the present invention is not limited to this and may be a V belt or the like.

[0031]

As described above, according to the first and second aspects.
According to the present invention, the rubber composition is a hydrogenated rubber comprising an ethylenically unsaturated nitrile-conjugated diene copolymer.
100 parts by weight, unsaturated carboxylic acid metal salt; 10 to 100
Parts by weight, organic peroxide; 0.2-10 parts by weight, carbon black; 10-35 parts by weight and plasticizer; 10-30
Since the rubber composition constitutes at least a part of the belt-constituting rubber portion of the power transmission belt, the rubber composition is reinforced by the chemical reaction between the hydrogenated rubber and the unsaturated carboxylic acid metal salt and carbon black. Due to the synergistic effect with the physical reinforcement, it is possible to obtain a transmission belt having further excellent properties such as abrasion resistance and bending fatigue resistance.

[Brief description of drawings]

FIG. 1 is a vertical sectional view of a V-ribbed belt.

FIG. 2 is a vertical sectional view of a toothed belt.

[Explanation of symbols]

 None

Claims (2)

[Claims] 1. A hydrogenated rubber comprising an ethylenically unsaturated nitrile-conjugated diene copolymer; 100 parts by weight; unsaturated carboxylic acid metal salt; 10 to 100 parts by weight; organic peroxide; 0.2 to 10 Parts by weight, carbon black; 10 to 3
A rubber composition containing 5 parts by weight and 10 to 30 parts by weight of a plasticizer. 2. A hydrogenated rubber comprising an ethylenically unsaturated nitrile-conjugated diene copolymer; 100 parts by weight, unsaturated carboxylic acid metal salt; 10 to 100 parts by weight, organic peroxide; 0.2 to 10 Parts by weight, carbon black; 10 to 3
A power transmission belt, wherein a rubber composition containing 5 parts by weight and 10 to 30 parts by weight of a plasticizer is used for at least a part of the rubber part constituting the belt.