JPH06117497A - Toothed belt - Google Patents

Abstract

PURPOSE:To improve durability by forming a rubber layer, covering tooth cloth for covering the tooth rubber part side surface in a timing belt, of rubber forming continuous phase and a rubber composition containing short fibers in which rubber molecules co-cross-linked with the rubber are grafted. CONSTITUTION:A belt body 5 is formed of a back rubber layer 2 and tooth rubber parts 3 disposed at the specified pitch along the longitudinal direction of a toothed belt A, and cover canvas 4 is attached to the respective surface of the tooth rubber parts 3 and the back rubber layer 2 between the tooth rubber parts 3, 3. Woven fabric expandable in the longitudinal direction of the toothed belts A is used as the cover canvas 4. A rubber composition, containing 3-30phr of short fibers of polyamide group synthetic fiber of 0.3mum in fiber diameter and 300mum in fiber length with the rubber molecules of acrylonitride-butadiene rubber or the like grafted, is applied as rubber cement to rubber such as H-NBR, and vulcanization-molded. This rubber cement oozes out to the surface to form a rubber layer 10.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a toothed belt used as, for example, a timing belt of an automobile engine, and more particularly to a low μ value added to a rubber layer covering a tooth cloth.
Regarding the improvement of materials.

[0002]

2. Description of the Related Art A toothed belt used as a timing belt for an automobile engine is required to have further improved durability as the engine has a higher output and a narrower width. For this purpose, it is especially necessary to improve the durability of the tooth rubber portion.

As one of the means for improving the durability of the tooth rubber portion, there is a method of increasing the wear resistance of the tooth rubber portion, and this involves a low μ of the surface of the tooth cloth covering the surface of the belt body on the tooth rubber portion side.
It is influential to achieve higher efficiency (lower friction coefficient). For this reason, conventionally, various low-μ substances have been added to the rubber layer covering the tooth cloth. As an example, for example, the actual exploitation 62
Japanese Patent Publication No. 179447 discloses a technique of mixing glass fiber powder, glass beads, carbon fiber powder, and aramid fiber powder in a rubber layer.

[0004]

However, since the low μ substance and the rubber have extremely different elastic moduli, the rubber layer will not be formed by simply mixing the low μ substance into the rubber layer as in the conventional example. When subjected to bending fatigue, stress concentrates on the interface between the low μ substance and rubber and becomes a crack initiation point, from which cracks in the rubber layer grow and hinder the reduction of μ. Therefore, the lowering of the surface of the tooth cloth cannot be expected to the extent that the amount of the low-μ substance mixed is increased, and it is actually difficult to sufficiently increase the wear resistance of the tooth rubber portion.

Further, the above-mentioned conventional low-μ substance easily becomes foreign matter in the rubber layer, and the foreign matter inhibits the adhesiveness between the tooth cloth and the belt body. On the contrary, the shear fatigue life of the rubber part is shortened.

The present invention has been made in view of the above points, and an object thereof is to improve the low μ substance added to the rubber layer to sufficiently lower the surface of the tooth cloth and to reduce the tooth rubber portion. To improve the wear resistance, and to prevent the shortening of the shear fatigue life of the tooth rubber part due to the obstruction of the adhesion between the tooth cloth and the belt body, thus effectively improving the durability of the tooth rubber part. To do.

[0007]

In order to achieve the above object, in the present invention, short fibers grafted with rubber molecules are used as the low μ substance.

Specifically, according to the present invention, a tooth cloth for covering the surface of the belt main body on the side of the tooth rubber portion is vulcanized integrally with the belt main body, and the tooth cloth is attached to the belt main body. It is premised on a toothed belt whose part comprises a rubber layer covering the tooth cloth.

In the invention of claim 1, the rubber layer is composed of a rubber composition of a rubber forming a continuous phase and a short fiber grafted with molecules of the rubber capable of co-crosslinking the rubber.

In the invention of claim 2, the above-mentioned claim 1 is adopted.
In the invention of, a short fiber grafted with rubber molecules,
It is composed of a polyamide-based synthetic fiber having a fiber diameter of 0.3 μm and a fiber length of 300 μm.

According to the invention of claim 3, the above-mentioned claim 2 is adopted.
In the invention, the content of the short fibers in the rubber composition is 3 to 30 phr as the fiber content.

Further, in the invention of claim 4, in the inventions of claims 1 to 3, the rubber forming the continuous phase contains hydrogenated acrylonitrile-butadiene rubber, and the rubber molecule capable of co-crosslinking with the rubber is acrylonitrile-butadiene rubber. Use system rubber.

[0013]

According to the first aspect of the invention, since the rubber layer is made to have a low μ due to the fiber content of the short fibers in the rubber composition, the surface of the tooth cloth can be made to have a low μ. Further, since the rubber molecules of the short fibers can be co-crosslinked with the rubber forming the continuous phase in the rubber composition, the fiber components of the short fibers in the rubber molecule are crosslinked with the rubber. As a result, the situation in which the rubber layer is cracked due to the concentration of stress at the interface between the low μ substance and the rubber is avoided, and the tendency of the low μ substance to become foreign matter is suppressed.

Further, in the invention of claim 2, the synthetic fibers of polyamide type having a fiber diameter of 0.3 μm and a fiber length of 300 μm are used for the short fibers grafted with the rubber molecules. An attached belt can be easily obtained.

According to the third aspect of the invention, the content of the short fibers in the rubber composition is 3 phr or more as the fiber content, so that the rubber layer can have a sufficiently low μ. On the other hand, when it is 30 phr or less, it is possible to avoid a situation in which the adhesiveness between the tooth cloth and the belt body is hindered by the polyamide synthetic fiber as the short fiber.

Further, in the invention of claim 4, the rubber forming the continuous phase contains hydrogenated acrylonitrile butadiene rubber (H-NBR) excellent in heat deterioration resistance, and rubber molecules capable of co-crosslinking with this rubber. Is an acrylonitrile butadiene rubber, the toothed belt according to any one of claims 1 to 3 can be easily obtained, and in combination with the heat deterioration resistance imparted by the H-NBR, the durability of the tooth rubber part is improved. The property is further improved.

[0017]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a toothed belt A according to this embodiment. The toothed belt A includes a belt main body 5 and a cover canvas 4 as a tooth cloth attached to the belt main body 5 with a rubber paste.

The belt body 5 has a back rubber layer 2 extending in the lengthwise direction, and a toothed belt A on the back rubber layer 2.
And a plurality of tooth rubber portions 3 arranged at an appropriate pitch along the length direction of the toothed belt 4 in the width direction of the toothed belt 4 in the back rubber layer 2. The wire 1 is embedded in a state of extending in the lengthwise direction of the toothed belt A. And
The cover canvas 4 is attached to each surface of the tooth rubber portion 3 and the back rubber layer 2 between the tooth rubber portions 3 and 3 adjacent to each other.

The belt body 5 is made of a material having excellent heat deterioration resistance such as well-known chlorosulfonated polyethylene rubber (CSM), alkylated chlorosulfonated polyethylene (ACSM), hydrogenated acrylonitrile butadiene rubber (H-NBR). And more preferably H-N
A peroxide vulcanization type material in which BR and unsaturated carboxylic acid metal salt are mixed is used. Other suitable materials may be used in consideration of heat deterioration resistance and solvent resistance.

The core wire 1 is prepared by bundling 100 to 2000 filaments of 0.75 to 6d fiber,
The glass cord is subjected to RFL treatment, and the aramid fiber is subjected to pretreatment and RFL treatment.

The cover canvas 4 is made of a woven fabric having elasticity in the lengthwise direction of the toothed belt A, and each of the braiding systems forming the woven fabric is a resorcin-formalin-rubber latex (RFL) liquid, It is desirable that the surface is coated with an epoxy resin solution or an isocyanate resin solution. This woven fabric is adhered to the belt main body 5 by being vulcanized and molded integrally with the belt main body 5 at the time of molding the belt after the rubber paste is dipped or applied. Then, the cover canvas 4 has a rubber layer 10 formed of the above-mentioned rubber paste exuding on the surface of the cover canvas 4.
It is covered with a part of. As the material of the cover canvas 4, polyamide fiber, polyester fiber or the like is preferably used.

A feature of the present invention is that the rubber paste forming the rubber layer 10 forms a continuous phase, for example, H-NBR.
Etc. and a rubber composition of fine diameter nylon (registered trademark) fibers as short fibers made of polyamide synthetic fibers grafted with rubber molecules such as acrylonitrile butadiene rubber that can be co-crosslinked with the rubber. ing. The fine nylon fiber has a fiber diameter of 0.3 μm and a fiber length of 3
The content in the rubber composition is 3 to 30 phr as the fiber content. This fine nylon fiber exerts its function as a low μ substance due to its fiber content.

In the toothed belt A constructed as described above, the rubber layer 10 is made to have a low μ due to the fiber component of the fine nylon fiber in the rubber composition. μ conversion is achieved. Since the rubber molecules of the fine diameter nylon fiber can be co-crosslinked with the rubber forming the continuous phase in the rubber composition, the fiber component of the fine diameter nylon fiber in this rubber molecule should be crosslinked with the rubber. become. This avoids a situation in which stress is concentrated at the interface between the fiber portion of the fine nylon fiber and the rubber, and stress is concentrated to cause cracks in the rubber layer 10,
Moreover, since the tendency of the fiber component to become foreign matter is suppressed, the abrasion resistance of the tooth rubber part 3 is increased in accordance with the decrease in the surface of the canvas 4, and the adhesiveness between the canvas 4 and the belt body 5 is improved. This is maintained and the reduction of the shear fatigue life of the tooth rubber part 3 is avoided. As a result, the durability of the tooth rubber part 3 is improved.

Further, since the content of the fine nylon fiber in the rubber composition is 3 phr or more as the fiber content, the rubber layer 10 can be sufficiently reduced in μ. On the other hand, since the content is 30 phr or less, it is possible to prevent the fiber component from inhibiting the adhesiveness between the cover canvas 4 and the belt body 5, and to prevent the surface of the canvas 4 from being impaired as long as the adhesiveness is not impaired. A sufficiently low μ can be achieved.

Further, in the rubber composition of the above-mentioned rubber paste, the rubber forming the continuous phase is assumed to contain hydrogenated acrylonitrile butadiene rubber (H-NBR) excellent in heat deterioration resistance, and can be co-crosslinked with this rubber. When the rubber molecule is an acrylonitrile butadiene type rubber, the above H
In combination with the heat deterioration resistance imparted by -NBR, the durability of the tooth rubber part 3 is further improved.

The present inventors specifically used six kinds of rubber glues having different mixing ratios of the fine nylon fibers as shown in the following Table 1, and used as a toothed belt A according to this embodiment. Inventive Examples 1 to 6 were prepared, and the wear test of the surface of each canvas 4 and the shear fatigue life test of the tooth rubber part 3, the durability test of the tooth rubber part 3, the abnormal noise test during belt running, and the measurement of the friction coefficient were performed. I went each. The fine nylon fibers used were grafted with H-NBR as acrylonitrile butadiene rubber. On the other hand, for comparison, Table 1
The toothed belts A of Comparative Examples 1 to 7 were prepared using seven types of rubber pastes each including the rubber composition shown in, and the same test was performed. H-NBR was used for the rubber forming the continuous phase in the rubber composition of each rubber paste. The above results are also shown in Table 1.

[0027]

[Table 1]

Compared with Comparative Examples 1 and 2 in which the low μ substance was not added at all, in Invention Examples 1 to 6, the friction coefficient was substantially halved and the wear amount was reduced to 14 to 45%.
It can be seen that the surface is sufficiently low μ. Also, regarding the shear fatigue life of the tooth rubber part 3, in Invention Examples 1 to 6, although fine-diameter nylon fibers were added, it was comparable to Comparative Examples 1 and 2, and conversely, fine-diameter nylon was used. Those having a small fiber content (Invention Examples 1 to 5) are rather excellent. The durability time of the tooth rubber part 3 is 1.3 to
1.9 times longer.

Although it contains the same fine nylon fiber as the low μ substance, the content is 40 phr (100
Comparative Example 3 which is 30 parts by weight (75 parts by weight)
Comparing Invention Examples 1 to 6 below, Comparative Example 3 has a smaller content of fine nylon fibers, so that the friction coefficient is smaller and the wear amount is also smaller. It can be seen that the lowering of μ proceeds substantially in proportion to the content rate. However, regarding shear fatigue, Invention Examples 1 to 1
No. 6 shows an excellent numerical value, and the invention examples 1 to 6 are also excellent in terms of abnormal noise. It is considered that this is because when the content is too high, the fine nylon fibers tend to become foreign substances in the rubber layer. It should be noted that Comparative Example 3 is superior to Comparative Examples 4 to 7 in terms of shear fatigue and durability.

In Comparative Examples 4 and 5 in which nylon short fiber powder was mixed as the low-μ substance, the friction coefficient was about the same level as in Invention Examples 1 to 6, and when compared with Comparative Examples 1 and 2. The amount of wear is reduced. However, when Comparative Examples 4 and 5 are compared with Invention Examples 1 to 6, the abrasion amount, the shear fatigue and the durability are inferior in Comparative Examples 4 and 5, and even if the low μ property is the same, nylon is used. It can be seen that short fiber powder still has a large tendency to become foreign matter. That is, in Invention Examples 1 to 6, the wear amount was 19 compared with Comparative Examples 4 and 5.
It is particularly low at ˜61%, and the shear fatigue is also 1.6 to 2.2 times longer. The durability time is 1.3 to 1.7 times as long.

In Comparative Examples 6 and 7 in which aramid short fiber powder was mixed as the low μ substance, the friction coefficient was at a level close to that of Inventive Examples 1 to 6, and the wear amount was further higher than in Comparative Examples 4 and 5 above. It is decreasing. However, in terms of wear amount, shear fatigue, and durability, Comparative Examples 6 and 7 are still inferior to Invention Examples 1 to 6, and even the aramid short fiber powder, the nylon short fiber powders of Comparative Examples 4 and 5 above. It can be seen that there is a large tendency to turn into foreign matter in the same manner as. That is,
In Invention Examples 1 to 6, the wear amount is 23 to
It is as low as 76%, and the shear fatigue is particularly long, 2.6 to 4.1 times. The durability time is 1.3 to 1.9 times longer.

Next, when Invention Examples 1 to 6 are compared with each other, the higher the content of the fine nylon fibers is, the smaller the friction coefficient is and the less the wear amount is. Has reached a ceiling. Furthermore, in invention example 6, shear fatigue and abnormal noise have begun to show a tendency of worsening.
From this, the content of fine nylon fiber is 7
It is determined that the upper limit is 5 parts by weight (30 phr as the fiber content).

[0033]

According to the toothed belt of the invention of claim 1,
The rubber layer contains short fibers grafted with a rubber molecule capable of co-crosslinking with the rubber forming the continuous phase of the rubber layer, so that the fiber component as a low μ substance of the short fibers is firmly bonded to the rubber. Since it can be cross-linked, it is possible to prevent the rubber layer from being cracked as in the conventional example. As a result, depending on the content of the above short fibers, the low μ
Since it is possible to improve the wear resistance of the tooth rubber portion, the durability of the tooth rubber portion can be improved. In addition, since the above-mentioned coupling can prevent the fiber component from becoming foreign matter, the adhesiveness between the tooth cloth and the belt main body can be favorably maintained, and the shear fatigue property of the tooth rubber portion is shortened. Can be avoided.

Further, according to the invention of claim 2, as the short fibers, a polyamide synthetic fiber having a fiber diameter of 0.3 μm and a fiber length of 300 μm is used. The belt can be easily obtained.

According to the third aspect of the invention, the short fibers made of the polyamide synthetic fiber are contained in the rubber composition in the range of 3 to 30 phr, so that the gap between the tooth cloth and the belt body is increased. The surface of the tooth cloth can be sufficiently reduced to the extent that it does not impair the adhesiveness.

Further, in the invention of claim 4, a rubber containing a hydrogenated acrylonitrile butadiene rubber (H-NBR) is used as a rubber forming a continuous phase, and an acrylonitrile butadiene type rubber is used as a rubber molecule capable of co-crosslinking with this rubber. By using the above, the toothed belt of the inventions of claims 1 to 3 can be easily obtained, and in combination with the heat deterioration resistance imparted by the H-NBR, the durability of the tooth rubber part can be further improved. Can be improved.

[Brief description of drawings]

FIG. 1 is a perspective view showing a toothed belt according to an embodiment of the present invention by cutting a part thereof.

[Explanation of symbols]

 3 Tooth rubber part 4 Cover canvas (tooth cloth) 5 Belt body 10 Rubber layer

 ─────────────────────────────────────────────────── ─── Continued Front Page (72) Hideaki Kawahara, Inventor Hideaki Kawahara, 3-2-15 Meiwadori, Hyogo-ku, Kobe, Hyogo Prefecture Bando Kagaku Co., Ltd.

Claims (4)

[Claims] 1. A tooth cloth for covering a surface of a belt main body on the side of a tooth rubber portion, and a tooth cloth which is vulcanized integrally with the belt main body to adhere the tooth cloth to the belt main body, and a part thereof covers the tooth cloth. In a toothed belt including a rubber layer, the rubber layer is made of a rubber composition of a rubber forming a continuous phase and a short fiber grafted with rubber molecules capable of co-crosslinking the rubber. Belt with teeth. 2. The toothed belt according to claim 1, wherein the short fibers grafted with rubber molecules are polyamide synthetic fibers having a fiber diameter of 0.3 μm and a fiber length of 300 μm. 3. The content of short fibers in the rubber composition is 3 to 30 phr as a fiber content.
The toothed belt described. 4. The rubber forming a continuous phase comprises a hydrogenated acrylonitrile butadiene rubber, and the rubber molecule capable of co-crosslinking with the rubber is an acrylonitrile butadiene type rubber. Toothed belt.