JPH0763242A - V-ribbed belt - Google Patents

Abstract

PURPOSE:To obtain a V-ribbed belt having excellent heat resistance, abrasion resistance and bending fatigue resistance even in use under severe conditions such as rising of the using atmospheric temperature, having no generation of trouble such as wear out failure, and having a long life. CONSTITUTION:A rib rubber layer 1 of a V-ribbed belt A made of H-NBR (hydrogenation acrylonitrile rubber) is formed into two-layer structure composed of a rib root part 1a and a rib tip part 1b. Short fibers 4 are compounded with H-NBR for constituting the rib root part 1a and orientated in the approximately belt width direction. And unsaturated carboxylic acid metallic salt is compounded with H-NBR for constituting the rib tip part lb.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improved V-ribbed belt.

[0002]

2. Description of the Related Art As is well known, V-ribbed belts are widely used in various applications as belts having both the flexibility of a flat belt and the high transmission of a V-shaped belt and compactness. The V-ribbed belt has a basic structure composed of a rib rubber layer, a core layer in contact with the rib rubber layer, and an upper canvas layer in contact with the core layer. In particular, a rubber material forming the rib rubber layer is selected. It is known that the heat resistance, wear resistance and flex fatigue resistance of V-ribbed belts are seriously affected.

Here, the structure of the conventional V-ribbed belt will be briefly described. For example, the rib rubber layer is made of chloroprene rubber (CR) to improve the bending fatigue resistance at the rib tip portion, while the rib root is improved. In some parts, CR is combined with short fibers, and the short fibers are oriented in the belt circumferential direction to improve wear resistance.

In addition, a rib rubber layer is formed of a rubber composition in which CR is mixed with short fibers, and the short fiber density is increased particularly at the rib root portion, and the short fiber density is reduced as the rib approaches the tip. Therefore, some of them have improved wear resistance and bending fatigue resistance.

[0005]

However, although the belts in any of these cases have average properties in terms of heat resistance, wear resistance and bending fatigue resistance, they have been It was not possible to meet the required higher heat resistance.

In order to improve the heat resistance so as to cope with this high heat resistance, a hydrogenated acrylonitrile rubber (hereinafter referred to as H-NBR) which is a heat resistant polymer is used instead of the CR used in the belt. There is a belt whose heat resistance is improved by using the rib rubber layer. However, in the case of this belt, while the life in the high temperature range is extended, the life in the normal temperature range (bending fatigue resistance) is only slightly improved as compared with the case of being composed of CR, and a large bending resistance is obtained. No improvement in fatigue was observed.

Further, in order to improve heat resistance and flex fatigue resistance, H-NBR is mixed with an unsaturated carboxylic acid metal salt such as zinc methacrylate or zinc acrylate and reinforced with short fibers. Although it is possible to construct a rib rubber layer by using it, in this case, although the heat resistance can be considerably improved, the flex fatigue resistance is higher than that of CR in the normal temperature range, especially in the condition with the reverse bending pulley. The result was inferior.

Therefore, the present inventor does not mix the unsaturated carboxylic acid metal salt and the short fiber into the H-NBR constituting the rib rubber layer at the same time, but by mixing them individually, the unsaturated carboxylic acid metal salt It was examined how the blending of salt or short fibers affects H-NBR. That is, when the rib rubber layer 1 ′ of the V-ribbed belt B is composed of the rubber composition in which the short fibers 4 are combined with the H-NBR (see FIG. 2), the unsaturated carboxylic acid is formed without combining the short fibers 4 with the H-NBR. When the rib rubber layer 1 ′ of the V-ribbed belt B is composed of a rubber composition containing a metal salt (see FIG. 3), two types of V-ribbed belt B are prepared.
(Compared with R), the wear resistance was good, and the flex fatigue resistance was excellent in the high temperature range, but the flex fatigue resistance in the normal temperature range was poor. On the other hand, the V-ribbed belt B was excellent in heat resistance and bending fatigue resistance (high temperature range and normal temperature range), but was inferior in wear resistance.

From the above experimental facts, in the rib rubber layer of the V-ribbed belt, the part where the wear resistance is more required than the other parts and the bending fatigue resistance is more required than the other parts. By properly using the rubber composition of the rib rubber layer 1 ′ used in the above and in the parts,
It was concluded that, when the respective drawbacks of the rubber composition are compensated for, and the V-ribbed belt as a whole is viewed, it is possible to combine heat resistance, abrasion resistance, and bending fatigue resistance in a well-balanced manner.

The present invention has been made in view of the above points, and an object thereof is to use elastomers having different physical properties at the rib tip portion and the rib root portion of the rib rubber layer in the V-ribbed belt. In other words, by using the elastomer having excellent heat resistance and abrasion resistance and the elastomer having excellent heat resistance and bending fatigue resistance separately, it has satisfactory heat resistance even if the ambient temperature of the V-ribbed belt rises. In addition, the wear resistance and the bending fatigue resistance are well balanced.

[0011]

To achieve the above object, the present invention provides a rib rubber layer composed of H-NBR,
For the V-ribbed belt provided with the core layer in contact with the rib rubber layer and the upper canvas layer in contact with the core layer, the following solution was taken.

That is, the first means for solving the problems of the present invention is that H-NBR constituting the rib root portion of the rib rubber layer is combined with short fibers, and the short fibers are oriented substantially in the belt width direction. Further, the present invention is characterized in that the unsaturated carboxylic acid metal salt is mixed with H-NBR forming the rib tip portion of the rib rubber layer.

A second solving means of the present invention is characterized in that, in the first solving means, the hydrogenated acrylonitrile rubber constituting the rib root portion of the rib rubber layer is also mixed with an unsaturated carboxylic acid metal salt.

A third solving means of the present invention is the first or second means.
In the solving means described above, the relationship between the thickness c of the rib root portion and the thickness d of the rib tip portion satisfies the equation 0.1 ≦ d / c ≦ 0.4.

A fourth solving means of the present invention is the H forming the rib root portion in any one of the first to third solving means.
-Aramid short fibers or polyamide short fibers are used as the short fibers to be combined with NBR.

A fifth solving means of the present invention is any one of the first to fourth solving means, wherein the unsaturated carboxylic acid metal salt is mixed with H-NBR constituting the rib root and the rib tip. It is characterized by using zinc methacrylate or zinc acrylate.

[0017]

With the above structure, in the first or second means for solving the problems of the present invention, the H-N forming the rib root portion of the rib rubber layer is formed.
Since short fibers are combined with BR and the short fibers are oriented in the belt width direction, not only the heat resistance which is a characteristic of H-NBR, but also lateral pressure resistance is increased and abrasion resistance is improved. In addition, since the unsaturated carboxylic acid metal salt is blended with H-NBR forming both the rib tip portion or the rib tip portion and the rib root portion of the rib rubber layer, not only heat resistance but also bending fatigue resistance improves. Therefore, when viewed as a V-ribbed belt as a whole, it is possible to combine heat resistance, wear resistance, and bending fatigue resistance in a well-balanced manner, and to use it stably with a long life even when used under severe conditions such as an increase in the temperature of the atmosphere in which it is used. be able to.

In the third solving means of the present invention, the relation between the thickness c of the rib root portion and the thickness d of the rib tip portion is expressed by the formula 0.1 ≦ d.
Since it is configured to satisfy the relationship of /c≦0.4, it is possible to maintain heat resistance, wear resistance, and bending fatigue resistance in a well-balanced manner. When d / c is less than 0.1 or exceeds 0.4, it is difficult to maintain heat resistance, wear resistance and bending fatigue resistance in a well-balanced manner.

In the fourth means for solving the problems of the present invention, aramid short fibers or polyamide short fibers are used as the short fibers to be combined with the H-NBR forming the rib root portion of the rib rubber layer, and therefore these short fibers have characteristics. Due to the high strength, high elastic modulus and heat resistance provided, it is possible to more reliably and stably improve wear resistance in addition to heat resistance.

In the fifth solution of the present invention, zinc methacrylate or zinc acrylate is used as the unsaturated carboxylic acid metal salt compounded in the H-NBR forming the rib root portion and rib tip portion of the rib rubber layer. The flex fatigue resistance can be improved more reliably and stably.

[0021]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows a V-ribbed belt A according to an embodiment of the present invention. This V-ribbed belt A has a ribbed rubber layer 1
And a core layer 3 in contact with the rib rubber layer 1 and an upper canvas layer 2 in contact with the core layer 3. Specifically, the rib rubber layer 1 includes a rib root portion 1a and a rib tip portion 1b. The core layer 3 is composed of a core body 3a and an adhesive rubber layer 3b.

Here, the rib rubber layer 1 is made of a rubber material containing H-NBR as a main component. Particularly, in the rib root portion 1a, the H-NBR is combined with the short fibers 4 and the short fibers 4 are almost formed. Oriented in the belt width direction. An unsaturated carboxylic acid metal salt may be further mixed in the H-NBR forming the rib root portion 1a. Further, in the rib tip portion 1b, H-NBR is mixed with an unsaturated carboxylic acid metal salt,
The short fibers 4 are not compounded like the rib root portion 1a.

The short fibers 4 to be combined with the H-NBR are preferably aramid short fibers or polyamide short fibers, and the unsaturated carboxylic acid metal salt to be mixed with the H-NBR is zinc methacrylate or zinc acrylate. desirable.

In the relationship between the thickness c of the rib base portion 1a and the thickness d of the rib tip portion 1b, 0.1 ≦ d / c
It is desirable to set so as to satisfy the relational expression ≦ 0.4. In the above relational expression, 0.1 ≦ d / c ≦
The reason for setting 0.4 is that d / c is less than 0.1,
This is because if it exceeds 0.4, it is difficult to maintain the heat resistance, wear resistance and bending fatigue resistance in a well-balanced manner.

V-ribbed belt A obtained by the above construction
Is composed of a rubber material in which the rib root portion 1a is compounded with H-NBR and a short fiber 4 such as an aramid short fiber, and the short fiber 4 is oriented substantially in the belt width direction. It is possible to secure heat resistance and wear resistance at the rib base portion 1a. On the other hand, since the rib tip portion 1b or both the rib tip portion 1b and the rib root portion 1a are made of a rubber material in which an unsaturated carboxylic acid metal salt is mixed with H-NBR, heat resistance at the rib tip portion 1b is improved. And flex fatigue resistance can be secured.

Therefore, the V-ribbed belt A as a whole has heat resistance, the rib root portion 1a is particularly excellent in wear resistance, and the rib tip portion 1b is particularly excellent in bending fatigue resistance. Even after that, there is no wear failure, and even if it is wound between small pulleys, it can be used without trouble for a long period of time.

Next, the present invention will be concretely described in comparison with a comparative example.

First, as Examples 1 and 2 of the present invention, the rib root portion 1a and the rib tip portion 1b of the rib rubber layer 1 are shown in Table 1.
A V-ribbed belt A (FIG. 1) composed of the rubber composition having the composition shown in FIG. On the other hand, as Comparative Examples 1 to 4,
A V-ribbed belt B (comparative examples 1 and 3 are shown in FIG. 2,
Comparative Examples 2 and 4 produced FIG. 3). In addition, in the configuration of the V-ribbed belt A (B) according to the example of the present invention and the comparative example,
The other members such as the upper canvas layer 2 and the core layer 3 other than the rib rubber layer 1 (1 ') are the same.

[0030]

[Table 1]

First, each V-ribbed belt A obtained above
For the heat resistance and wear resistance of (B), see FIG.
The V-ribbed belts A (B) were run under the conditions as shown in (1) to perform a bench test, and the belt running time until the V-ribbed belts A (B) were damaged was measured. The measurement result is shown in FIG.

As is clear from the results shown in FIG. 6, in the case of Examples 1 and 2 of the present invention, Comparative Example 1 and Comparative Example 3, no abnormality was observed even after running for 1,000 hours. On the other hand, in both Comparative Examples 2 and 4, abnormal wear was recognized.

In FIG. 4, P1 is a drive pulley (φ120 mm / 4900 rpm) and P2 is a driven pulley (φ120 mm / 8.
8kw) and P3 are tension pulleys (φ45 mm), and each V-ribbed belt A (B) has these pulleys P1 to P1.
The belt was wound between P3 as shown in the figure, a constant tension (SW: 85 kgf) was applied by the tension pulley P3, and the belt was made to run in an atmosphere of 85 ± 3 ° C.

Regarding the bending fatigue resistance of each V-ribbed belt A (B), a bench test was conducted by running each V-ribbed belt A (B) under the conditions shown in FIG.
The belt running time was measured until each V-ribbed belt A (B) was damaged. The measurement result is shown in FIG.

As is clear from the results shown in FIG. 7, in the case of Examples 1 and 2 of the present invention, the belt running time was about 2.5 times longer than in Comparative Examples 1 and 3, and the small pulley was used. It turned out to be excellent in durability.

In FIG. 5, P4 is a drive pulley (φ60 mm / 5100 rpm), P5 is a driven pulley (φ60 mm), P
Reference numeral 6 is a tension pulley (φ60 mm), P7 and P8 are idler pulleys (φ50 mm) to be used on the back side, and each V-ribbed belt A (B) is wound between these pulleys P4 to P8 as shown in the figure. A load is applied to the driven pulley P5 in the direction of the arrow so that the driven pulley P5 runs at room temperature.

Further, in Examples 1 and 2 of the present invention, the thickness c of the rib root portion 1a and the rib tip portion 1 in the rib rubber layer 1 are set.
The ratio d / c to the thickness d of b is 0 (substantially the rib root portion 1
a)), 0.1, 0.2, 0.3, 0.4, 0.5 and 0.6 in order, and wear reduction (g) after 100H heat resistance test and small pulley durability test time ( H) and were measured. The measurement result is shown in FIG.

As is clear from the results shown in FIG. 8, if the d / c ratio is within the range of 0.1 to 0.4, the heat resistance test 100
It has been found that the wear loss after H is relatively small, which is desirable, while the small pulley durability test time is stable at a high level when the d / c ratio is 0.2 or more. From this, it is considered that the ratio of d / c is preferably in the range of 0.1 to 0.4 in consideration of the measurement results of both.

[0039]

As described above, claims 1, 2, and
According to the present invention according to 4,5, in the rib rubber layer of the V-ribbed belt, short fibers (desirably aramid short fibers or polyamide short fibers) are combined with H-NBR forming the rib root portion, and the short fibers are combined. Of the unsaturated carboxylic acid metal salt (preferably zinc methacrylate or acryl) in the H-NBR forming the rib tip portion or both the rib tip portion and the rib root portion of the rib rubber layer. Zinc acid). As a result, the rib root portion of the rib rubber layer can be increased in lateral pressure resistance due to the combination of short fibers, and wear resistance can be improved. On the other hand, not only the heat resistance but also the bending fatigue resistance can be improved due to the blending of the unsaturated carboxylic acid metal salt at the rib tip portion of the rib rubber layer. Therefore, as a whole V-ribbed belt, the heat resistance, abrasion resistance and bending fatigue resistance required when the temperature of the atmosphere in which the belt is used rises can be stably satisfied at the same time.

According to the third aspect of the present invention, the relationship between the thickness c of the rib root portion and the thickness d of the rib tip portion is not only heat resistance but also excellent wear resistance and bending fatigue resistance are most balanced. A relationship that can be exhibited well, that is, the formula 0.1 ≦ d / c ≦
Since it is set to satisfy 0.4, it is possible to exhibit excellent heat resistance, wear resistance and bending fatigue resistance in a stable state even under severe conditions such as a rise in ambient temperature. It can be used with a long life without causing trouble.

[Brief description of drawings]

FIG. 1 is a sectional view of a V-ribbed belt according to Examples 1 and 2 of the present invention.

FIG. 2 is a cross-sectional view of V-ribbed belts according to comparative examples 1 and 3.

FIG. 3 is a cross-sectional view of V-ribbed belts according to comparative examples 2 and 4.

FIG. 4 is a diagram showing a layout of each pulley and a belt for carrying out a heat resistance test.

FIG. 5 is a diagram showing a layout of each pulley and a belt for carrying out a small pulley durability test.

FIG. 6 is a graph showing measurement results of a heat resistance test.

FIG. 7 is a graph showing measurement results of a small pulley durability test.

FIG. 8: Wear loss (g) after 100 hours of heat resistance test
It is the figure which plotted the belt running time (H) in a small pulley endurance test.

[Explanation of symbols]

 AV ribbed belt 1 Rib rubber layer 1a Rib root 1b Rib tip 2 Upper canvas layer 3 Core layer 4 Short fibers

Claims (5)

[Claims] 1. A rib rubber layer composed of hydrogenated acrylonitrile rubber, and a core layer in contact with the rib rubber layer,
In a V-ribbed belt provided with an upper canvas layer in contact with the core layer, short fibers are compounded in the hydrogenated acrylonitrile rubber constituting the rib root portion of the rib rubber layer, and the short fibers are substantially in the belt width direction. A V-ribbed belt, characterized in that the hydrogenated acrylonitrile rubber, which is oriented and constitutes the rib tip portion of the rib rubber layer, contains an unsaturated carboxylic acid metal salt. 2. The V as claimed in claim 1, wherein the hydrogenated acrylonitrile rubber constituting the rib root portion of the rib rubber layer contains an unsaturated carboxylic acid metal salt.
Ribbed belt. 3. The relation between the thickness c of the rib root portion and the thickness d of the rib tip portion satisfies the equation 0.1 ≦ d / c ≦ 0.4. The V-ribbed belt according to 1 or 2. 4. The short fibers to be combined with the hydrogenated acrylonitrile rubber constituting the rib root portion are aramid short fibers or polyamide short fibers.
The V-ribbed belt according to any one of 3 above. 5. The unsaturated carboxylic acid metal salt blended with the hydrogenated acrylonitrile rubber constituting the rib root portion and the rib tip portion is zinc methacrylate or zinc acrylate. V-ribbed belt according to any one of 1.