JPH10103412A - Power transmission belt - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prolong running lifetime of a belt by preventing a compressible rubber layer from being cracked even while running in a reversed bending state. SOLUTION: A core wire 3 comprising a code is buried in a binding rubber layer 2. An extensible rubber layer 5 is disposed in an upper portion of the binding rubber layer 2, and a compressible rubber layer 7 is also disposed in a lower portion thereof. A power transmission belt 1 whose periphery is covered with a cover canvas 4 includes both an upper rubber layer 9 and a lower rubber layer 10 in the compressible rubber layer 7. The lower rubber layer 10 has a smaller thickness than the upper rubber layer 9, and moreover, the lower rubber layer 10 is made of rubber compound having a higher thermal resistance than the upper rubber layer 9.

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, and more particularly, to a power transmission belt in which the compression rubber layer is less likely to crack even when the belt is reversely bent and the running life of the belt is improved.

[0002]

2. Description of the Related Art As a power transmission belt, there is a wrapped belt in which a belt periphery is covered with a cover canvas. In this belt, a cord made of a cord with low elongation and high strength is embedded in an adhesive rubber layer, and a compression rubber layer is provided below the core wire and an extension rubber layer is provided above the belt. In particular, it is desired that the belt used in the driving device of the agricultural implement improve the heat transmission performance at higher temperatures and the transmission performance without lowering the crack resistance.

[0003] For this reason, belts generally used for agricultural equipment and the like have also tended to impart heat resistance to the cover canvas, the core wire, and the rubber composition, which are the constituent members. For example, a V-belt having improved abrasion resistance at high temperatures using a canvas woven from a blended yarn of an organic fiber mainly composed of polymetaphenylene isophthalamide fiber (aramid fiber) and a cotton fiber as a cover canvas, has been developed. It is disclosed in Japanese Patent Publication No. Hei 5-37065. Further, as a rubber composition, a chloroprene rubber composition, a hydrogenated nitrile rubber composition, or the like is used for a compressed rubber layer.

[0004]

However, even in a belt in which a canvas woven with a blended yarn of aramid fiber and cotton fiber is used as a cover canvas for covering the periphery of the belt, the belt slip rate is high and the transmission performance is reduced. There was a problem to do. Further, even when a heat-resistant rubber composition was used for the compressed rubber layer, cracks were easily formed in the compressed rubber layer at an early stage when the belt was reversely run. As a countermeasure, a belt in which two layers of canvas are laminated below the compressed rubber layer has been proposed.
When running in the normal direction, which is the normal direction, the rigidity increases, and when the belt is bent with a small pulley, heat is generated and the hardness of the rubber increases rapidly, which tends to cause early cracking of the rubber. Transmission efficiency was reduced. Furthermore,
At the time of laminating this canvas at the time of manufacture, care must be taken so as not to wrinkle the canvas, and time is required for the process, which increases the cost of the product.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and an object of the present invention is to provide a power transmission belt in which the compression rubber layer is less likely to crack even in reverse bending running, thereby improving the running life of the belt. And

[0006]

That is, according to the first aspect of the present invention, an adhesive rubber layer in which a cord made of a cord is embedded, an extension rubber layer above the adhesive rubber layer, and a compression rubber layer below the adhesive rubber layer. In a power transmission belt in which a rubber layer is arranged and the belt periphery is covered with a cover canvas, an adhesive rubber layer in which a cord made of cord is embedded, an expanded rubber layer above the adhesive rubber layer, and a compression layer below the adhesive rubber layer A power transmission belt in which a rubber layer is disposed and a belt periphery is covered with a cover canvas, wherein an upper rubber layer and a lower rubber layer are used for the compressed rubber layer, the lower rubber layer is thinner than the upper rubber layer, and the upper rubber layer Since the belt is made of a rubber composition having better heat resistance than the layer, the belt is easily bent in the reverse direction, so that the compressed rubber layer is less likely to crack and the running life of the belt can be improved.

In the invention of claim 2 of the present application, an upper rubber layer composed of a chloroprene rubber composition and a lower rubber layer composed of a hydrogenated nitrile rubber composition or a rubber composition of chlorosulfonated polyethylene are used for the compressed rubber layer. By the combination, the belt is more easily bent backwards, so that the compressed rubber layer is less likely to crack, and the running life of the belt can be improved.

In the invention according to claim 3 of the present application, since the lower rubber layer is a power transmission belt having a thickness of 0.8 to 2.5 mm, the belt is easily reversely bent and the compressed rubber layer is less likely to crack. In addition, the amount of the lower rubber layer can be limited to reduce the cost.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the accompanying drawings. FIG. 1 is a perspective view of a power transmission belt according to the present invention. The belt 1 has a configuration in which a cord 3 made of a polyester or aramid cord is embedded in an adhesive rubber layer 2, An extension rubber layer 5 made of the same material as the adhesive rubber layer 2 is provided on the upper part, and a compression rubber layer 7 is provided below the adhesive rubber layer 2. The entire belt is surrounded by the cover canvas 4.

The compressed rubber layer 7 is formed of two layers, an upper rubber layer 9 and a lower rubber layer 10. The lower rubber layer 10 is thinner than the upper rubber layer 9, and the lower rubber layer 9 has a belt The rubber composition having the highest heat resistance among the constituent layers is used. During reverse bending running of the belt, the lower rubber layer 9 is a region that is subjected to repeated deformation of stretching and shrinking in the longitudinal direction of the belt, but if a rubber composition having excellent heat resistance is used for this layer, Rubber hardness does not increase easily, rubber elasticity can be maintained for a long time, and cracks are not easily formed. The lower rubber layer 10 has a thickness of 0.8
When the thickness is smaller than 0.8 mm, the improvement in crack resistance of the compressed rubber layer 7 is small.
If it exceeds 5 mm, the crack resistance is improved, but the cost is increased.

For the upper rubber layer 9, a rubber composition composed of natural rubber, styrene-butadiene rubber, nitrile rubber, chloroprene rubber alone or a mixture thereof is used, while for the lower rubber layer 10, alkylated chlorosulfanated polyethylene is used. And a rubber composition such as a hydrogenated nitrile rubber, and a mixed polymer of a hydrogenated nitrile rubber and a metal salt of an unsaturated carboxylic acid.

The chlorosulfonated polyethylene has a chlorine content of 15 to 35% by weight, preferably 25 to 32% by weight.
And a chlorosulfonated low-density polyethylene having a sulfur content in the range of 0.5 to 2.5% by weight.

[0013] Hydrogenated nitrile rubber is a rubber obtained by hydrogenating an acrylonitrile-butadiene copolymer.
The hydrogenation rate is 80% or more, and preferably 90% or more in order to exhibit heat resistance and ozone resistance characteristics. A hydrogenated nitrile rubber having a hydrogenation rate of less than 80% has extremely low heat resistance and ozone resistance. In consideration of oil resistance and cold resistance, the amount of bound acrylonitrile is preferably in the range of 20 to 45%. The iodine value is 10 to 40 g / 100.
g.

Short fibers such as aramid, nylon, polyester, vinylon, and cotton may be added to the upper rubber layer 9 and the lower rubber layer 10 so as to be oriented in the belt width direction.

The cover canvas 4 is a cloth woven in a plain weave, a twill weave, a satin weave, or the like using a yarn made of cotton, nylon, polyester, vinylon, and polyarylate fibers.

After the cover canvas 4 is subjected to RFL treatment, the rubber composition is subjected to fiction coating to obtain a canvas with rubber. The RFL solution is obtained by mixing a latex with an initial condensate of resorcinol and formalin, and the latex used here is chloroprene, styrene / butadiene / vinylpyridine terpolymer, hydrogenated nitrile, N
BR and the like.

[0017]

EXAMPLES Hereinafter, the effects of the present invention will be confirmed by more specific experimental examples. Example 1, Comparative Examples 1-2 As a core wire, a 1,100 denier polyethylene terephthalate fiber was twisted in the up and down direction at a number of twists of 9.0 times / 10 cm and a number of lower twists of 21.0 times / 10 cm, and was twisted in the upside down direction. An unprocessed cord having a × 5 twist configuration and a total denier of 16,500 was prepared. Next, the untreated cord was pre-diped with 5% by weight of a polyisocyanate compound (PAPI-135: manufactured by M-D Kasei Co., Ltd.) using an isocyanate-based adhesive composed of 95% by weight of toluene, and then about 17% by weight.
After drying at 0 to 180 ° C, RFL solution (CR latex 1)
00 parts by weight, resorcinol 14.6 parts by weight, formalin 9.2 parts by weight, caustic soda 1.5 parts by weight, water 262.5
(Parts by weight), and then subjected to a stretching heat-setting treatment at 200 to 240 ° C. to obtain a treated cord.

Further, the canvas was woven using a spun cotton yarn as the cover canvas. The canvas was subjected to friction with a chloroprene rubber composition to obtain a canvas with rubber.

The wrapped V belt (upper width 16.5 mm, thickness 8.0 mm,
(Length 1016 mm).

[0020]

[Table 1]

The method of manufacturing this wrapped V-belt is as follows. That is, an upper rubber layer having a thickness of 4 mm and a thickness of 1.5 mm
After winding a rubber sheet corresponding to a compressed rubber layer having a lower rubber layer having a thickness of 1 mm around a mantle, the core wire is spun, and a rubber sheet corresponding to the same stretched rubber layer as the upper rubber layer is wound thereon. After cutting the belt of this molded body to a predetermined width, it is skived and then wrapped with a cover canvas. After the obtained belt was fitted into a ring mold, it was vulcanized to complete a wrapped V-belt.

A wrapped V-belt of Comparative Example 2 was prepared by laminating a 2-ply cotton canvas in which a chloroprene rubber composition was frictionally applied to a region corresponding to a lower rubber layer of a compressed rubber layer. The size of the belt is the same as in the first embodiment.

The running life of the thus obtained wrapped V-belt was measured by a reverse bending running test. Table 2 shows the results. In the reverse bending running test of the belt, the wrapped V-belt was hung on a driving pulley (diameter 90 mm) and a driven pulley (diameter 120 mm), and a tension pulley (diameter 60 mm) was brought into contact with the back of the belt. The vehicle was run under the conditions of a rotation speed of 1,800 rpm and a load of 3.7 kW.

[0024]

[Table 2]

From Table 2, it can be seen that the belt of this example has a long time until cracks occur in the compressed rubber layer during reverse bending running, and is excellent in durability and cracking properties.

[0026]

As described above, according to the first aspect of the present invention, the adhesive rubber layer having the cords embedded therein is
In the power transmission belt in which an extension rubber layer and a compression rubber layer are disposed below the adhesive rubber layer and the belt periphery is covered with a cover canvas, an adhesive rubber layer in which a cord made of cord is embedded, In a power transmission belt in which an extension rubber layer is disposed above the adhesive rubber layer and a compression rubber layer is disposed below the adhesion rubber layer, and the periphery of the belt is covered with a cover canvas, the compression rubber layer has an upper rubber layer and a lower rubber layer. Used, the lower rubber layer is thinner than the upper rubber layer, and is made of a rubber composition that is more heat-resistant than the upper rubber layer. This has the effect of improving the running life of the vehicle.

In the invention of claim 2 of the present application, an upper rubber layer composed of a chloroprene rubber composition and a lower rubber layer composed of a hydrogenated nitrile rubber composition or a rubber composition of chlorosulfonated polyethylene are used for the compressed rubber layer. The combination has the effect that the belt is more likely to reversely bend and the compression rubber layer is less likely to crack, thereby improving the running life of the belt.

In the invention according to claim 3 of the present application, since the lower rubber layer is a power transmission belt having a thickness of 0.8 to 2.5 mm, the belt is easily bent in a reverse direction, so that the compressed rubber layer is less likely to crack. In addition, there is an effect that the amount of the lower rubber layer can be limited to reduce the cost.

[Brief description of the drawings]

FIG. 1 is a partially sectional perspective view of a power transmission belt according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Power transmission belt 2 Adhesive rubber layer 3 Core wire 4 Cover canvas 5 Extension rubber layer 7 Compressed rubber layer 9 Upper rubber layer 10 Lower rubber layer

Claims (3)

[Claims] 1. A power supply comprising: an adhesive rubber layer in which a cord made of a cord is embedded; an extension rubber layer above the adhesive rubber layer; and a compression rubber layer below the adhesive rubber layer. In the transmission belt, an upper rubber layer and a lower rubber layer are used for the compressed rubber layer, and the lower rubber layer is made of a rubber composition thinner than the upper rubber layer and more excellent in heat resistance than the upper rubber layer. Characteristic power transmission belt. 2. The power transmission device according to claim 1, wherein an upper rubber layer made of a chloroprene rubber composition and a lower rubber layer made of a hydrogenated nitrile rubber composition or a rubber composition of chlorosulfonated polyethylene are used for the compressed rubber layer. belt. 3. The power transmission belt according to claim 1, wherein the lower rubber layer has a thickness of 0.8 to 2.5 mm.