JPH10103413A - Transmission belt - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent generation of cracking from an interface of a rubber layer and a compression rubber layer and an interface of an adhesive rubber layer and a core wire by using a raw material rubber formed by coagulating rubber latex in which short fibers are mixed and dispersed in an adhesive rubber layer. SOLUTION: In a V-belt 1, an outer peripheral surface of an adhesive rubber layer 3 for holding a core wire 2 to a suitable position in a spiral state is covered with an upper sail cloth 5, and an outer peripheral surface of a compression rubber layer 4 is covered with a bottom sail cloth 6. A short fiber 7 is arranged in the belt width direction and is mixed in the adhesive rubber layer 3 and a compression rubber layer 4 respectively. A raw material rubber formed by coagulating rubber latex in which the short fibers 7 are mixed and dispersed in the adhesive rubber layer 3, and thereby, adhesive performance of the matrix rubber and the short fiber 7 is improved in the adhesive rubber layer 3, and it is possible to prevent cracking from generating from both interfaces. Dispersion degree of the short fiber 7 is improved easily so as to stabilize the quality of the adhesive layer 3 of a high elastic modulus.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power transmission belt such as a V-belt or a V-ribbed belt, and more particularly, to a power transmission belt having an improved adhesive rubber layer for improved durability.

[0002]

2. Description of the Related Art In transmission belts, polyester fibers,
A high tensile strength core wire made of aramid fiber or the like is held at an appropriate position by an adhesive rubber layer. For this reason, the adhesive rubber layer is required to have high adhesiveness to the core wire, and has a fluidity such that it flows by heat during the belt vulcanization molding so as to be in a state of being in intimate contact with the core wire. High soft rubber is commonly employed.

On the other hand, the compression rubber layer of the transmission belt is required to have a high elastic modulus from the viewpoint of preventing deformation and improving the transmission performance of the belt, and generally contains short fibers. Rubber is employed.

Therefore, since the difference in elastic modulus between the adhesive rubber layer and the compressed rubber layer or the core wire is large, the interface between the adhesive rubber layer and the compressed rubber layer or the interface between the adhesive rubber layer and the core wire is large. However, there is a problem that stress is concentrated and cracks occur.

As a conventional countermeasure, a short fiber or a large amount of carbon is mixed into the adhesive rubber layer to increase its elastic modulus (Japanese Utility Model Publication No. 1-105513).
In other words, instead of covering the entire core with an adhesive rubber layer, the upper half of the core is covered with an adhesive rubber layer, and the lower half of the core is covered with a compressed rubber layer (Japanese Patent Laid-Open Publication No. 57-204351).

[0006]

However, although the mixing of the short fibers is effective as a means for increasing the elastic modulus of the adhesive rubber layer, the adhesion between the short fibers and the matrix rubber tends to be insufficient. There is a problem that cracks are generated from the interface between the fiber and the rubber. Further, to obtain a high elastic modulus comparable to that of the compressed rubber layer, it is necessary to mix a large amount of short fibers. The adhesive rubber between the core wires becomes porous, leading to premature breakage of the belt. In addition, there is also a problem that the increase in the amount of the carbon also increases the viscosity of the rubber and decreases the moldability of the belt,
Therefore, there is a limit to the increase, and an elastic modulus as high as expected cannot be obtained.

On the other hand, in the proposal of covering the upper half of the core wire with an adhesive rubber layer and covering the lower half of the core wire with a compressed rubber layer, the degree of crack generation on the lower half side of the core wire is suppressed. However, this does not fundamentally solve the problem that cracks occur from the interface between the adhesive rubber layer and the core wire and the interface between the adhesive rubber layer and the compressed rubber layer.

[0008]

Therefore, in the present invention, when the adhesive rubber layer is filled with short fibers, the way of mixing the short fibers is devised so as to reduce the distance from the interface between the short fibers and the matrix rubber. Without causing the problem of crack generation, it is possible to obtain an adhesive rubber layer having a high quality and a stable elastic modulus, so that the interface between the adhesive rubber layer and the compressed rubber layer or the adhesive rubber layer and the core wire can be obtained. An object of the present invention is to solve the problem that cracks are generated from the interface, and also to solve the problem that the short form fiber is mixed to lower the formability of the belt.

<Invention according to claim 1> The present invention relates to a power transmission belt comprising an adhesive rubber layer for holding a cord extending in the belt longitudinal direction at an appropriate position, and a compression rubber layer. In addition, a raw rubber obtained by coagulating a rubber latex in which short fibers are mixed and dispersed is used.

In the present invention, since the short fibers are mixed in a rubber latex state, the adhesion between the matrix rubber and the short fibers in the adhesive rubber layer becomes good, and cracks are generated from the interface between the two. And it is easy to increase the degree of dispersion of the short fibers, and to obtain an adhesive rubber layer having a stable and high modulus of elasticity to obtain an interface between the adhesive rubber layer and the core wire and the adhesion. This is advantageous in preventing the generation of cracks from the interface between the rubber layer and the compressed rubber layer.

As the matrix rubber for the adhesive rubber layer, various types can be used. From the viewpoint of heat resistance and the like, CR (chloroprene rubber) or ACSM is used.
(Alkylated chlorosulfonated polyethylene) is preferred.

<Invention according to claim 2> According to the present invention, in the power transmission belt according to claim 1, the short fiber is made of one fiber selected from aramid fiber, cotton, and silk. It is characterized by having been done.

In the case of the present invention, since the short fibers themselves are high-elasticity fibers such as aramid fibers, cotton, and silk, it is advantageous to obtain a high elasticity adhesive rubber layer with a small amount of short fibers.

<Invention according to claim 3> The present invention is characterized in that, in the transmission belt described in claim 2, the short fibers are fibrillated pulp.

In the present invention, since the short fibers are made of fibrillated pulp, the surface area is large, and therefore, the adhesiveness between the short fibers and the matrix rubber of the adhesive rubber layer is enhanced.

According to a fourth aspect of the present invention, in the transmission belt according to any one of the first to third aspects, the short fiber has a fiber length of 1 mm or less. Features.

In the present invention, since the fiber length of the short fibers is short, even if the mixing amount is increased to increase the elastic modulus of the adhesive rubber layer, the decrease in the fluidity of the obtained rubber is small, and the molding of the belt is difficult. This makes it easier to prevent the adhesive rubber between adjacent core wires from becoming porous.

Here, from the viewpoint of increasing the modulus of elasticity of the adhesive rubber layer, it is preferable that the diameter of the short fiber is reduced and the ratio of the fiber length / fiber diameter is increased. In addition, from the viewpoint of preventing a decrease in the fluidity of the rubber, the amount of the short fibers is set to 20 parts by weight or less based on 100 parts by weight of the raw rubber in the rubber composition for the adhesive rubber layer. Is preferred.

[0019]

According to the first aspect of the present invention, since the raw rubber obtained by coagulating the rubber latex in which short fibers are mixed and dispersed is used for the adhesive rubber layer of the power transmission belt, While the adhesion between the matrix rubber and the short fibers in the layer becomes good, it becomes easy to obtain a high-modulus adhesive rubber layer having a high degree of dispersion of the short fibers and a stable quality. This is advantageous in preventing cracks from being generated at the interface with the short fibers, the interface between the adhesive rubber layer and the core wire, and the interface between the adhesive rubber layer and the compressed rubber layer.

According to a second aspect of the present invention, in the transmission belt according to the first aspect, the short fiber is one fiber selected from aramid fiber, cotton, and silk having a high elastic modulus. Is advantageous in obtaining an adhesive rubber layer having a high elastic modulus.

According to the third aspect of the present invention, in the transmission belt according to the second aspect, fibrilized pulp is used as the short fiber, so that the short fiber and the matrix rubber of the adhesive rubber layer are used. This is advantageous in that the adhesion between the two is improved, and the generation of cracks at the interface between the two is prevented.

According to the fourth aspect of the present invention, in the transmission belt according to any one of the first to third aspects, the short fiber has a fiber length of 1 mm or less. It is advantageous for ensuring the fluidity of the layer rubber and preventing the adhesive rubber between adjacent core wires from becoming porous.

[0023]

BEST MODE FOR CARRYING OUT THE INVENTION

(Embodiment of Transmission Belt) FIG. 1 shows a low-edge type V-belt 1 as an embodiment of a transmission belt according to the present invention. In the V-belt 1, reference numeral 2 denotes a core wire provided in a spiral shape and extending in the circumferential direction of the belt. Reference numeral 3 denotes an adhesive rubber layer for holding the core wire 2 at an appropriate position in a spiral state. It is a compressed rubber layer provided in. The outer peripheral surface of the adhesive rubber layer 3 is covered with the upper canvas 5, and the inner peripheral surface of the compressed rubber layer 4 is covered with the bottom canvas 6. Each of the adhesive rubber layer 3 and the compressed rubber layer 4 contains short fibers 7 oriented in the belt width direction.

FIG. 2 shows a V-ribbed belt 11 of the same low edge type as another embodiment. The V
In the ribbed belt 11, reference numeral 12 denotes a cord provided in the same manner as the V-belt 1, reference numeral 13 denotes an adhesive rubber layer for holding the cord 12 in an appropriate position, reference numeral 14 denotes a compression rubber layer, and reference numeral 14 denotes a compression rubber layer. A plurality of ribs 14a extending in the circumferential direction are provided in parallel with each other. 15 is an upper canvas. Also in the V-ribbed belt 11, the short fibers 7 are mixed into each of the adhesive rubber layer 13 and the compressed rubber layer 14 while being oriented in the belt width direction.

(Examples and Comparative Examples) -Example 1- An unvulcanized rubber sheet for an adhesive rubber layer and an unvulcanized rubber sheet for a compressed rubber layer were prepared by kneading and rolling a rubber composition having the following composition. A rubber sheet was formed. Then, the rubberized canvas for the upper canvas, the unvulcanized rubber sheet for forming the outer peripheral portion of the adhesive rubber layer, the core wire, and the inner peripheral portion of the adhesive rubber layer are formed in a cylindrical belt molding die. An unvulcanized rubber sheet for forming, an unvulcanized rubber sheet for a compressed rubber layer,
And a rubberized canvas for bottom canvas in order, and vulcanizing the unvulcanized rubber at a predetermined temperature and time to form a V-belt shown in FIG.

[Rubber compound of adhesive rubber layer] CR (chloroprene) 84.6 parts by weight Kevlar pulp master batch 20 parts by weight Carbon FEF 30 parts by weight Hydrous silica 20 parts by weight Plasticizer (DOS) 8 parts by weight Sulfur 1 part by weight Oxidation Zinc 5 parts by weight Magnesium oxide 4 parts by weight Antioxidant 3 parts by weight

As the chloroprene, Neoprene GRT manufactured by Showa Denko DuPont was used. Kevlar pulp master batch is 6F723 (pulp diameter: 10 to 12 μm, average fiber length: 0.8 mm) manufactured by DuPont. Octylated diphenylamine was used as an anti-aging agent.

The unvulcanized rubber sheet for the compressed rubber layer was formed using a rubber composition having the following composition. Short fibers were mixed during kneading.

[Rubber composition of compressed rubber layer] Sulfur-modified CR (chloroprene) 100 parts by weight Carbon black 50 parts by weight Oil 8 parts by weight Magnesium oxide 4 parts by weight Zinc oxide 5 parts by weight Other processing aids, antioxidants, etc.

The reinforcing filler such as carbon black is 40 to 60 parts by weight, the oil such as process oil and plasticizer is 3 to 10 parts by weight, and the magnesium oxide as a crosslinking agent is 3 to 5 parts by weight. And about 3 to 10 parts by weight of zinc oxide. For short fibers (reinforcing fibers), cotton, nylon, vinylon,
Aramid or the like can be used alone or in combination, and is oriented in the belt width direction. The shape of this short fiber (L
/ D), by adjusting the mixing amount, the elastic modulus in the grain direction of the compressed rubber layer (dynamic elastic modulus E ′ at 25 ° C. in the viscoelasticity test) is about 100 to 400 MPa for the V belt, and V
For a ribbed belt, the pressure is about 50 to 200 MPa.

The above-mentioned V-belt is characterized in that Kevlar pulp masterbatch is used as a part of the rubber in the adhesive rubber layer. This Kevlar pulp master batch is obtained by mixing fibrillated Kevlar pulp with chloroprene rubber latex, dispersing the mixture by stirring, and coagulating the mixture.

This master batch contains 23 parts by weight of Kevlar pulp per 100 parts by weight of rubber.
Therefore, in the case of the rubber composition for an adhesive rubber layer, when the total amount of chloroprene rubber (the total amount of neoprene GRT and master batch) is 100 parts by weight, the amount of short fibers is 4.6 parts by weight. In addition, JI of the rubber composition
The Mooney viscosity Ms1 + 4 according to SK 6300 (rotor size S, test temperature 100 ° C., preheating 1 minute, rotor operation time 4 minutes) is 44, and the ratio of the elastic modulus Ea of the adhesive rubber layer to the elastic modulus Ec of the compressed rubber layer ( Ea / Ec) is 0.6.

Example 2 An adhesive rubber layer was formed using the same rubber composition as in Example 1 except that the amount of chloroprene was 69.2 parts by weight and the amount of Kevlar pulp master batch was 40 parts by weight. Chloroprene rubber 10 in the rubber composition for the adhesive rubber layer
The amount of short fibers per 0 parts by weight is 9.2 parts by weight. The Mooney viscosity of the rubber composition is 53, and the elastic modulus ratio (Ea / Ec) is 0.8.

Example 3 An adhesive rubber layer was formed using the same rubber composition as in Example 1 except that the amount of chloroprene was 53.8 parts by weight and the amount of Kevlar pulp master batch was 60 parts by weight. The amount of short fibers per 100 parts by weight of the chloroprene rubber in the rubber composition is 13.8 parts by weight. The rubber composition has a Mooney viscosity of 58 and an elastic modulus ratio (Ea /
Ec) is 1.1.

Comparative Example 1 An adhesive rubber layer was formed using the same rubber composition as in Example 1 except that the amount of chloroprene was 38.4 parts by weight and the amount of Kevlar pulp master batch was 80 parts by weight. The amount of short fibers per 100 parts by weight of the chloroprene rubber in the rubber composition is 18.4 parts by weight. The rubber composition had a Mooney viscosity of 69 and an elastic modulus ratio (Ea /
Ec) is 1.4.

Comparative Example 2 An adhesive rubber layer was formed using the same rubber composition as in Example 1 except that the amount of chloroprene was 100 parts by weight and the amount of Kevlar pulp masterbatch was zero. The Mooney viscosity of the rubber composition is 40, and the elastic modulus ratio (Ea / Ec)
Is 0.15.

Comparative Example 3 An adhesive rubber layer was formed with the same rubber composition as in Example 1 except that the amount of chloroprene was 100 parts by weight and the amount of Kevlar pulp was 5 parts by weight (no master batch).
The Mooney viscosity of the rubber composition is 45, and the elastic modulus ratio (Ea / Ec) is 0.7.

Comparative Example 4 Example 1 was repeated except that the amount of chloroprene was 100 parts by weight, the amount of carbon was 40 parts by weight, and the amount of hydrous silica was 30 parts by weight.
An adhesive rubber layer was formed with a rubber composition having the same composition as in Example 1 (without short fibers). The Mooney viscosity of the rubber composition is 75
And the elastic modulus ratio (Ea / Ec) is 0.2.

(Evaluation of Examples and Comparative Examples) For each of the above Examples and Comparative Examples, the workability was evaluated as ○, △-△, △.
In addition to the four grades of × and ×, a belt running test was performed in the manner shown in FIG. 3 to measure the life of the belt. In FIG. 3, reference numeral 20 denotes a test V-belt, 21 denotes a driving pulley, and 22 denotes a driven pulley. The conditions of the running test are as follows.

[Running test conditions] Driving pulley diameter 85 mm Driving pulley diameter 85 mm Driving pulley rotation speed 4900 rpm Load W 100 kg Load 1PS Atmospheric temperature 20 ° C. (temperature variation is + 10 ° C., −0 ° C.)

The evaluation results are shown in Table 1.

[0042]

[Table 1]

In each of Examples 1 to 3 and Comparative Example 1, short fibers were dispersed in rubber latex and short fibers were mixed into the adhesive rubber layer by a master batch method. As the Mooney viscosity increases and the processability decreases, the elastic modulus ratio increases. In the case of Comparative Example 1, a porous film was observed in the photograph of the cross section of the adhesive rubber layer, but the separation of the rubber and the core wire of the adhesive rubber layer from the porous portion progressed, and the life was extended.
Therefore, it can be seen that when the amount of short fibers is large as in Comparative Example 1, it is disadvantageous for the moldability of the belt.

Comparative Example 2 is an example in which no short fiber is mixed in the adhesive rubber layer, and the adhesive rubber layer has a low elastic modulus and a short life. Comparative Example 3 was obtained by adding the short fibers to the masticated rubber and kneading them, so that the short fibers were unevenly distributed,
Cracks extend from the unevenly distributed portions, and the life is shorter than in Examples 1 to 1. Therefore, it is understood that mixing and dispersing the short fibers in the rubber latex stage as in Examples 1 to 3 is effective for preventing cracks in the adhesive rubber layer. In Comparative Example 4, an attempt was made to increase the elastic modulus of the adhesive rubber layer by increasing the amount of carbon and hydrated silica, but the Mooney viscosity was too high and the workability was reduced. This indicates that there is a limit in increasing the elastic modulus by increasing the amount of carbon or the like.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a V-belt as an embodiment of the present invention.

FIG. 2 is a sectional view showing a V-ribbed belt as an embodiment of the present invention.

FIG. 3 is a diagram showing a mode of a belt running test.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 V belt 2,12 core wire 3,13 Adhesive rubber layer 4,14 Compression rubber layer 5,15 Upper canvas 6 Bottom canvas 7 Short fiber

Claims (4)

[Claims] 1. A transmission belt comprising an adhesive rubber layer for holding a core wire extending in the belt longitudinal direction at an appropriate position, and a compression rubber layer, wherein a rubber in which short fibers are mixed and dispersed in the adhesive rubber layer. A power transmission belt comprising a raw rubber obtained by coagulating latex. 2. The transmission belt according to claim 1, wherein one of the short fibers is selected from aramid fibers, cotton, and silk. . 3. The transmission belt according to claim 2, wherein the short fibers are fibrillated pulp. 4. The power transmission belt according to claim 1, wherein the short fibers have a fiber length of 1 mm or less.