JPH08216283A - Toothed belt - Google Patents

Abstract

PURPOSE: To improve heat resistance while inner heating, impact resilience, and adhesive properties to a core wire and a canvas are secured in a toothed belt. CONSTITUTION: A belt body 12 of a toothed belt 11 is formed of a hydrogenated nitrile rubber as a raw material, and a core wire 13 is buried along a longitudinal direction in its inside. In order to improve heat resistance, a rate of hydrogenation to the raw material rubber is determined to be 91.5-93.5%. 1-3 pts. of a sulfur vulcanizer is added to 100 pts. of the raw material rubber. As a vulcanization accelerator, that contains 0.3-2 pts. of dialkyl-dithiocarbamate metallic salt and 0.5-5 pts. of thiuram series and sulfenic amide series is added to 100 pts. of the raw material rubber.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a toothed belt for transmitting a rotational force of each shaft between an engine crankshaft, a cam shaft, a balancer shaft and the like in an internal combustion engine.

[0002]

2. Description of the Related Art Conventionally, a toothed belt has, for example, a tooth portion formed on one surface of a belt body and a core wire embedded in the belt body. In recent years, as the performance of internal combustion engines has improved, the rotational speed of the crankshaft has increased, and a large load has been generated to drive various auxiliary machines. Therefore, the temperature around the toothed belt is becoming higher.

As the raw material rubber used for the belt body, hydrogenated nitrile rubber has recently been used as a high-performance heat-resistant belt for internal combustion engines instead of chloroprene rubber.

Hydrogenated nitrile rubber has heat resistance because it is hydrogenated. On the other hand, in the case of vulcanizing with sulfur and a sulfur vulcanization accelerator, the vulcanized rubber is increased by increasing the proportion of hydrogenation. The cross-linking point of is decreased. Therefore, even if it shows excellent heat resistance in a static environment, heat is generated from the rubber itself in a dynamic environment in which the rubber repeatedly expands and contracts at high speeds (hereinafter,
Internal heat generation), the impact of the negative side such as the impact resilience (hereinafter referred to as permanent set) that tries to restore the rubber deformation under load is deteriorated. That is, the heat resistance of the toothed belt does not expand as expected even if the raw material rubber with an increased hydrogenation amount is used, and it is becoming difficult to meet the above-mentioned demands of the internal combustion engine.

In order to solve such a problem, for example, in JP-A-63-270753, a hydrogenated nitrile rubber is treated with an ethylenically unsaturated carboxylic acid metal salt such as zinc methacrylate whose vulcanization method is changed. A rubber cross-linked with a peroxide such as dicumyl peroxide is disclosed. However, although this rubber is slightly improved in terms of increasing the rigidity accompanied by heat resistance and elasticity, it is still insufficient in terms of suppressing internal heat generation.

On the other hand, when peroxide vulcanization is carried out, the surface of the canvas is deteriorated by radicals generated from the peroxide vulcanizing agent, the durability of the canvas covering the belt teeth is deteriorated, and Adhesion with rubber may be hindered, resulting in a problem of reduced running life.

[0007]

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and the internal heat generation of the belt main body is suppressed to a low level even during high-speed running under high load, and a special adhesion treatment is applied. Even if it is not used, the adhesiveness between the rubber and the core wire, and the rubber and the canvas can be kept high, and by maintaining the performance of the canvas that covers the teeth, the teeth do not chip easily and the running life is long. The purpose is to obtain a toothed belt.

[0008]

A toothed belt according to the present invention has a tooth portion formed on at least one surface, the surface of the tooth portion is covered with a canvas, and the core wire extends in the longitudinal direction. Has a belt body embedded therein, and the belt body uses a hydrogenated nitrile rubber having a hydrogenation rate of 91% or more as a raw material rubber, and 1 to 3 parts with respect to 100 parts of the raw material rubber.
Parts of a sulfur-based vulcanizing agent, 0.3 to 2 parts of a metal salt of a dialkyl dithiocarbamic acid salt formed with a metal of Group VIa of the periodic table, and 0.5 to 5 parts of a thiuram-based and a sulfenamide-based salt. It is characterized in that it is formed of a rubber to which a vulcanization accelerator containing a vulcanization accelerator and a vulcanization acceleration aid are added.

Hydrogenated nitrile rubber has a hydrogenation rate of 80.
%, The heat resistance will be improved, but if the hydrogenation rate exceeds 91%, the residual double bonds will not be completely vulcanized, and the heat resistance of the rubber in a dynamic environment will be sufficient. Does not grow. Therefore, in the power transmission belt of the present invention, the belt main body is made of a hydrogenated nitrile rubber having a hydrogenation rate of 91% or more as a raw material, and the sulfur-based vulcanizing agent and the cyclic rate of 1 to 3 parts are used with respect to 100 parts of the raw rubber. It is formed by a vulcanization acceleration aid containing a dialkyl dithiocarbamic acid as a metal salt of Group VIa, and a rubber to which the vulcanization acceleration aid is added. In addition, a cord is embedded in the belt body along the belt longitudinal direction.

In the present specification, the hydrogenation rate with respect to the raw rubber is indicated by the value measured by the iodine value method. In addition, in the present specification, the high-molecular-weight hydrogen nitrile rubber refers to a raw rubber having a Mooney viscosity of 91 or more at 100 ° C., and a normal-molecular-weight hydrogen nitrile rubber at the same temperature. The Mooney viscosity is less than 91.

The hydrogenation rate of the raw rubber is preferably 91.5-93.5%.

The sulfur vulcanizing agent is at least one of powdered sulfur and insoluble sulfur.

The alkyl group of the dialkyl / dithiocarbamic acid metal salt contained in the vulcanization accelerator may be either a methyl group or an ethyl group. The metal of the metal salt of dialkyl dithiocarbamic acid is Group VIa which has the same periodic table as sulfur used in the vulcanizing agent. The Group VIa metal may be selenium or tellurium.

The vulcanization accelerating aid is, for example, zinc white.

The core wire is made of high strength glass fiber.

The canvas covering the surface of the belt body is, for example, a woven cloth having nylon threads and / or aramid threads.

The toothed belt of the present invention will be described below with reference to the drawings.

FIG. 1 is a perspective view in which a part of a toothed belt 11 according to an embodiment of the present invention is cut away. A tooth portion 14 is formed on one surface of the belt main body 12, and on the pitch line of the belt main body 12, a core wire 13 whose upper twist is S twist and a core wire 13 whose upper twist is Z twist are juxtaposed. (However, in FIG. 1, the S-twisted and Z-twisted core wires 13 are not distinguished). The surfaces of these tooth portions 14 are covered with a canvas 16 composed of aramid fibers and / or nylon fibers.

In the embodiment, an ethylenically unsaturated nitrile-conjugated diene-based highly saturated copolymer rubber (hydrogenated nitrile rubber) is used as the raw material rubber constituting the belt body 12. An ethylenically unsaturated nitrile is a nitrile group (-C
N) is a compound formed by addition, such as acrylonitrile. The conjugated diene is a compound in which two double bonds are adjacent to each other, such as butadiene and isoprene.

In an embodiment, the raw material hydrogenated nitrile rubber is mixed with a sulfur-based vulcanizing agent and at least one of tetramethylthiuram disulfide, dipentamethylenethiuram tetrasulfide and N-cyclohexyl-2-benzothiazyl sulfenamide. And a vulcanization accelerator containing diethyl dithiocarbamate tellurium, carbon black, trimellitate isonolyl, stearic acid, N-isopropyl-N'-phenyl-p, in addition to zinc vulcanization accelerator. -Using rubber with phenylenediamine added. The vulcanization accelerator preferably contains all of diethyl dithiocarbamate tellurium, tetramethylthiuram disulfide, dipentamethylene thiuram tetrasulfide and N-cyclohexyl-2-benzothiazyl sulfenamide.

For the core wire 13, high strength glass fiber is used.

The canvas 16 is twilled with an aramid yarn 17 provided along the belt longitudinal direction and a nylon yarn 18 provided along the belt width direction. However, the structure of these threads, the weave of the canvas 16 and the like need not be limited to these. For example, the yarn in the longitudinal direction of the belt may be a nylon yarn having excellent rigidity and heat resistance, or may be a crimped yarn made of a nylon yarn. The aramid yarn may have a covering specification. Further, the canvas 16 may be satin weave, plain weave and various modified weaves depending on the purpose.

The canvas 16 formed in this way
Is subjected to treatment with resorcin / formaldehyde / latex aqueous solution containing carboxyl nitrile rubber as a latex component and adhered to the belt body 12. If necessary, it may be treated with a rubber paste.

[0024]

【Example】

[Example Rubber, Comparative Rubber and Conventional Rubber] Table 1 shows the compounding ratio of the example rubber, and Table 2 shows the compounding ratio of the comparative rubber and the conventional rubber.

[0025]

[Table 1]

In Table 1, the unit of * 1 is%, the unit of * 2 is an anonymous number, the unit of * 3 is part by weight, and the unit of * 4 is an abbreviation for N-isopropyl-N'-phenyl-p-phenylesiamine.
* 5 is tetramethylthiuram disulfide, dipentamethylenethiuram tetrasulfide and N-cyclohexyl-2-benzothiazyl sulfenamide, * 6 is an abbreviation for diethyl dithiocarbamate tellurium, and * 7 is JI.
Measured value at room temperature by S-A hardness meter, * 8 is measured value by JIS-A hardness meter at normal temperature after 280 hours under 140 ° C thermal environment, * 9 is room temperature rubber physical property hardness The value (unknown number) of the difference from the physical properties of heat resistant rubber, * 10 is based on the Goodrich flexo test (ASTM D 623-62).
As a result of measurement under the temperature condition of 100 ° C (unit is Celsius temperature), * 11 is the same as * 10 (unit is%). *** indicates unblended, and ----- indicates that there are no items to be described.

[0027]

[Table 2]

In Table 2, the unit of * 1 is%, the unit of * 2 is an anonymous number, the unit of * 3 is part by weight, and the unit of * 4 is an abbreviation of N-isopropyl-N'-phenyl-p-phenylesiamine.
* 5 is tetramethylthiuram disulfide, dipentamethylenethiuram tetrasulfide and N-cyclohexyl-2-benzothiazyl sulfenamide, * 6 is an abbreviation for diethyl dithiocarbamate tellurium, and * 7 is JI.
Measured value at room temperature by S-A hardness meter, * 8 is measured value by JIS-A hardness meter at normal temperature after 280 hours under 140 ° C thermal environment, * 9 is room temperature rubber physical property hardness The value (unknown number) of the difference from the physical properties of heat resistant rubber, * 10 is based on the Goodrich flexo test (ASTM D 623-62).
As a result of measurement under the temperature condition of 100 ° C (unit is Celsius temperature), * 11 is the same as * 10 (unit is%). *** indicates unblended, and ----- indicates that there is no description.

Example rubber 1 has a hydrogenation rate of 93.5%.
To 100 parts of the raw material hydrogenated nitrile rubber, 60 parts of carbon black and 10 parts of trimellit-isonolyl are added.
Part, stearic acid 1.0 part, N-isopropyl-N-
1.0 part of phenyl-p-phenylenediamine, 0.8 part of sulfur, 2.7 parts of tetramethylthiuram disulfide, dipentamethylenethiuram tetrasulfide and N-cyclohexyl-2-benzothiazyl sulfenamide, Diethyl dithiocarbamate tellurium 1.
It is a compounded rubber with 0 parts added.

Example rubber 2 is a hydrogenated nitrile rubber 1 having a hydrogenation rate of 92.3%, which is lower than that of example rubber 1.
In 00 parts, 60 parts of carbon black, 10 parts of trimellitate-isonolyl, 1.0 part of stearic acid, 1.0 part of N-isopropyl-N-phenyl-p-phenylenediamine, 0.8 part of sulfur, Tetramethylthiuram
It is a compounded rubber in which 2.7 parts of disulfide, dipentamethylene thiuram tetrasulfide and N-cyclohexyl-2-benzothiazyl sulfenamide and 1.0 part of diethyl dithiocarbamate tellurium are added.

Example rubber 3 is a hydrogenated nitrile rubber 1 having a hydrogenation rate of 91.5%, which is lower than that of example rubber 2.
In 00 parts, 60 parts of carbon black, 10 parts of trimellitate-isonolyl, 1.0 part of stearic acid, 1.0 part of N-isopropyl-N-phenyl-p-phenylenediamine, 0.8 part of sulfur, Tetramethylthiuram
It is a compounded rubber to which 2.7 parts of disulfide, dipentamethylene thiuram tetrasulfide and N-cyclohexyl-2-benzothiazyl sulfenamide and 1.0 part of diethyl dithiocarbamate tellurium are added.

In Example rubber 4, 100 parts of hydrogenated nitrile rubber having a hydrogenation rate of 92.5% which is between Example rubber 1 and Example rubber 2 was mixed with 60 parts of carbon black.
Parts, trimellitate-isonolyl 10 parts, stearic acid 1.0 part, N-isopropyl-N-phenyl-p-phenylenediamine 1.0 part, sulfur 0.8 parts, tetramethylthiuram disulfide, dipenta Methylene thiuram tetrasulfide and N-cyclohexyl-2-
It is a compounded rubber to which 2.7 parts of benzothiazyl-sulfenamide and 1.0 part of diethyl tellurium dithiocarbamate are added.

The rubber used as the comparative rubber was 100 parts of hydrogenated nitrile rubber having a hydrogenation rate of 93.5%, which is the same as that of Example rubber 1, 60 parts of carbon black, 10 parts of trimellitate isonolyl and stearin. 1.0 part of acid,
1.0 part of N-isopropyl-N-phenyl-p-phenylenediamine, 0.5 part of sulfur, tetramethylthiuram disulfide, dipentamethylenethiuram tetrasulfide and N-cyclohexyl-2-benzothiazyl sulfenamide Is a compounded rubber consisting of 2.7 parts. Compared with Example rubbers 1 to 4, they differ in that the amount of sulfur is reduced and that tellurium diethyl dithiocarbamate is not added.

The rubber used for the conventional rubber has a hydrogenation rate of 9
It is 0.5% and is a hydrogenated nitrile rubber having a hydrogenation rate lower than those of the example rubbers 1 to 4. The composition is 100 parts of hydrogenated nitrile rubber, 60 parts of carbon black,
10 parts trimellitate-isonolyl, 1.0 part stearic acid, 1.0 part N-isopropyl-N-phenyl-p-phenylenediamine, 0.5 part sulfur, tetramethylthiuram disulfide, dipentamethylenethiuram. A compounded rubber composed of 2.7 parts of tetrasulfide and N-cyclohexyl-2-benzothiazyl-sulfenamide. Further, as in the comparative rubber, no tellurium diethyl dithiocarbamate was added.

The sulfur of the vulcanizing agent may be powdered sulfur or insoluble sulfur.

[Measurement Method and Evaluation Method of Rubber Hardness in Thermal Environment] A dumbbell-shaped rubber sample whose hardness was measured at room temperature was
It was placed in a constant temperature bath in which hot air of 140 ° C circulates, and allowed to stand for 280 hours in a thermal environment. After returning to room temperature, the hardness was measured again. A rubber sample having a small difference in hardness before and after being placed in a constant temperature bath has excellent heat resistance, but a rubber sample having a large difference in hardness does not have excellent heat resistance. The results are shown in Table 1 and Table 2.
"Normal rubber physical properties / rubber hardness", "heat resistant rubber physical properties / rubber hardness", and "heat resistant rubber physical properties / hardness increase".

[Measurement Method and Evaluation Method of Internal Heat Generation] The internal heat generation was measured by Goodrich flexo test (ASTM D 6
23-62 Standard Methods of Test for COMPRESSIO
N FATIGUE OF VULCANIZED RUBBER). The rubber test pieces were 0.77 inches (1
9.6 mm) cylindrical shape was used. 10 degrees Celsius
0 degree, the number of times of pressing is 1800 times / minute, and the distance of pressing is 0.
121 inches (3.07 mm) with a load of 23 pounds (10
Under the condition of 2 Newton), the temperature rise of the test piece was measured using a thermocouple. A small measured value means that the internal heat generation of the rubber sample is small, and a large measured value means that the internal heat generation of the rubber sample is large. The results are shown in the columns of "Dynamic physical properties / internal heat generation" in Tables 1 and 2.

[Measurement Method and Evaluation Method of Permanent Set] With respect to the permanent set, the rate of deformation associated with the Goodrich flexo test was measured and displayed as a percentage. A small value means that the rate of deformation remaining after removing the load is small, and a large value means that the rate of deformation is large. The results are shown in Tables 1 and 2 as "dynamic physical properties.
It is shown in the "Permanent set" column.

[Increase in Hardness of Example Rubber] As shown in Table 3, the degree of increase in hardness (measured by JIS-A hardness meter, the same applies hereinafter) after 140 ° C. × 280 hours in a heat resistance test is the hydrogenation rate. Of the example rubber 3 in which the ratio is 91.5% is plus 13,
Example rubber 2 having a hydrogenation rate of 92.5% was plus 12, and Example rubber 4 having a hydrogenation rate of 92.5% was plus 12 and an example rubber 1 having a hydrogenation rate of 93.5%. Then it is a plus 11 increase. The hardness increase of conventional rubber with a hydrogenation rate of 90.5% shown in Table 2 is plus 1.
7 indicates that the heat resistance in a static environment is excellent.

[Internal heat generation of example rubber] As shown in Table 1, in a dynamic environment, the internal heat generation of the sample of Example rubber 3 having a hydrogenation rate of 91.5% is plus 10.5 °. C,
A sample of Example rubber 2 having a hydrogenation rate of 92.3% is plus 9.5 ° C., and an example rubber 4 having a hydrogenation rate of 92.3% is used.
Sample is plus 9.5 ° C, hydrogenation rate is 93.5%
The value of plus 9.5 ° C. is shown in the sample of the example rubber 1 of. This is smaller than the internal heat generation value of 11 ° C of the conventional rubber sample shown in Table 2, and it can be seen that the rubber of each example has excellent heat resistance under a dynamic environment.

[Example Rubber Permanent Set] Regarding the permanent set in such a dynamic environment,
The value of Example rubber 3 having a hydrogenation rate of 91.5% is 0.6.
%, And the value of Example rubber 2 having a hydrogenation rate of 92.3% is 0.
The value of Example rubber 4 having a hydrogenation rate of 7% and 92.3% is 0.7%, and the value of example rubber 1 is 0.8%. This value is smaller than the conventional permanent set value of 0.9%, and is superior in heat resistance to conventional rubber in a dynamic environment.
It shows that it has excellent performance to restore the original shape.

[Comparison of Example Rubber, Comparative Rubber and Conventional Rubber] As shown in Table 2, heat resistance test 140 ° C. × 28
The degree of increase in hardness after 0 hour is plus 13 in the comparative rubber having a hydrogenation rate of 93.5%, and the hydrogenation rate is 9%.
It is smaller than the plus 17 of the conventional rubber of 0.5%, which shows that the heat resistance of the comparative rubber is improved under the static environment of the rubber. However, the heat resistance of the comparative rubber does not reach that of each rubber of the examples.

As shown in Table 2, the values of both internal heat generation and permanent set of the comparative rubber are larger than those of the conventional rubber. This indicates that, under the dynamic environment of the comparative rubber and the conventional rubber, the cross-linking point does not increase simply by increasing the hydrogenation rate, and the restoring force against external load is poor.

[Comparison with High Molecular Weight Type] As shown in Table 3, the high molecular weight type hydrogenated nitrile rubber also had a hydrogenation amount of 92.5% and had the same vulcanization system as that of the example rubbers. When used, the internal heat generation and the permanent set were both excellent under the dynamic environment. However,
The adhesive strength per 25 mm between the hydrogenated nitrile rubber and the core wire was 196 Newton in the case of the conventional molecular weight rubber, but was only 127 Newton in the case of the high molecular weight type rubber.

[0045]

[Table 3]

In Table 4, the unit of * 1 is%, the unit of * 2 is an unnamed number, the unit of * 3 is part by weight, and * 4 is an abbreviation for N-isopropyl-N'-phenyl-p-phenylesiamine.
* 5 is tetramethylthiuram disulfide, dipentamethylenethiuram tetrasulfide and N-cyclohexyl-2-benzothiazyl sulfenamide, * 6 is an abbreviation of diethyl dithiocarbamate tellurium, and * 10 is Goodrich flexo test (ASTM D 623-6
Based on 2), the measurement result under 100 ° C temperature condition (unit is Celsius temperature), * 11 is the same as * 10 (unit is%).

[Example Belt, Comparative Example Belt and Conventional Belt] In order to confirm the performance as a belt, Example rubber 1, Example rubber 4, Comparative example rubber and conventional rubber shown in Tables 1 and 2 are selected. Then, a toothed belt was prepared using these rubbers. These are referred to as Example belt 1, Example belt 2, Comparative example belt, and Conventional belt, respectively.

[0048]

[Table 4]

In Table 4, the unit of * 1 is%, the unit of * 2 is an unnamed number, and * 14 is that the belt is laid on two axes, 12
JIS-before and after running for 1000 hours at a rotation speed of 6000 rpm for 1 minute in a temperature environment of 0 ° C.
Difference in the measured value at room temperature by the hardness meter of A, * 15 is * 14
It is a result when a test similar to the above is performed under a temperature environment of 140 ° C.

[Running Belt Hardness Test Method and Evaluation Method in Thermal Environment] In order to early evaluate the performance of the example belt, the comparative example belt and the conventional belt, a running test in a thermal environment was conducted. The deterioration of the rubber that constitutes the belt is represented by an increase in the hardness of the rubber. Therefore, the thermal environment is 120 ° C, the rotation speed is 6000 rpm for 1 minute, and the rubber is run for 1000 hours. Was measured and the amount of change in hardness was taken for evaluation. When the difference in hardness is small, it can be evaluated that the heat resistance is excellent, and when the difference in hardness is large, it cannot be evaluated that the heat resistance is excellent. The rubber hardness was measured on the back surface of the running belt. The results are shown in the column of "Belt back surface hardness increase" in Table 4.

[Test Method and Evaluation Method of Belt Life under Thermal Environment] The belt was run at a rotational speed of 6000 rpm for 1 minute in a temperature environment of 140 ° C. surrounded by a heat insulating material. The belt life was measured by measuring the running time from the start of running to tooth loss and evaluated by the number of hours. The result is shown in the column of "Time until tooth loss" in Table 4.

[Increase in Rubber Hardness of Conventional Belt] A core body made of high-strength glass fiber is embedded in a belt body made of a conventional hydrogenated nitrile rubber having a hydrogenation rate of 90.5%, and sulfur vulcanization is performed. A conventional belt, in which the formed tooth portion is covered with a canvas made of nylon 6,6, was run for 1000 hours in a thermal environment of 120 ° C, and the hardness of the rubber constituting the belt increased by plus 15. .

[Increase in Rubber Hardness of Comparative Example Belt] On the other hand, a core wire made of high-strength glass is embedded in a belt main body made of comparative example rubber whose hydrogenation rate is increased to 93.5%.
The comparative example belt in which the tooth portion formed by sulfur vulcanization is covered with a nylon 6 and 6 canvas cloth was run for 1000 hours in a heat environment of 120 ° C, and the hardness of the rubber was plus 13, which is the conventional value. It was smaller than the hardness increase of the rubber of the belt.

[Increase in Rubber Hardness of Example Belt 1] Using Example Rubber 1 which is a hydrogenated nitrile rubber having a hydrogenation rate of 93.5%, a core wire made of high-strength glass is embedded and made of nylon. In the example belt 1 in which the tooth portion is covered with the canvas, the hardness of the rubber when running for 1000 hours in the thermal environment of 120 ° C. is plus 12, which is a smaller value than the comparative example belt. However, there was not much difference.

[Increase in Rubber Hardness of Example Belt 2] A core wire made of high-strength glass was embedded in a belt body made of Example rubber 4 having a hydrogenation rate of 92.5%, and molded by sulfur vulcanization. In the example belt 2 in which the tooth portion is covered with the canvas made of the aramid fiber and the nylon fiber, the hardness of the rubber is 1,000 when running for 1000 hours in the thermal environment of 120 ° C. It was found that the increase in hardness was low compared to the example belt.

[Belt Life of Conventional Belt and Comparative Example Belt] A conventional belt using hydrogenated nitrile rubber having a hydrogenation rate of 90.5% was run under a temperature environment of 140 ° C. It became a chip. A comparative example belt made of conventional rubber with a hydrogenation ratio of 93.5%, which is higher than that of conventional belts, and made with nylon canvas, had tooth loss after 700 hours of running under the same thermal environment. When driving down, life extension is small.

[Belt Life of Example Belt 1] Using hydrogenated nitrile rubber having the same hydrogenation rate as that of the comparative example belt, that is, 93.5%, as the vulcanization accelerator, diethyl dithiocarbamate tellurium, tetramethylthiuram disulfide,
Dipentamethylene thiuram tetrasulfide and N
Example 1 using cyclohexyl-2-benzothiazyl sulfenamide Example rubber 1 using belt 1
Caused tooth loss after running for 900 hours in a temperature environment of 140 ° C. Compared with conventional belts, the heat resistance life is considerably extended.

[Belt Life of Example Belt 1] Hydrogenated nitrile rubber having a hydrogenation rate of 92.5% was used, and diethyl dithiocarbamate tellurium was used as a vulcanization accelerator.
Example rubber 2 using tetramethyl thiuram disulfide, dipentamethylene thiuram tetrasulfide and N-cyclohexyl-2-benzothiazyl sulfenamide, and an example using a canvas made of aramid fiber and nylon fiber In Belt 2, tooth loss occurred after running for 1200 hours. Combined with the effect of covering the teeth with a canvas made of aramid fiber, which has excellent heat resistance, the heat-resistant life of the belt is extended.

The toothed belt of the present invention can also be applied to a double toothed belt having belt teeth on both sides.

[0060]

As described above, according to the present invention, since the internal heat generation of the rubber is small even in the sulfur vulcanization, the deterioration of the rubber itself and the adhesion are suppressed in the belt used in the thermal environment. It Moreover, since the permanent set is good, the tooth chipping of the belt tooth is suppressed. Further, since the deterioration of the canvas and the inhibition of the adhesion between the core wire and the rubber as caused by peroxide vulcanization do not occur, the performance of the canvas covering the belt teeth is maintained. Further, since the high molecular weight type of hydrogenated nitrile rubber is not used, the rubber and the canvas, and the rubber and the core wire are surely bonded to each other, and the belt having a long life is obtained.

[Brief description of drawings]

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

[Explanation of symbols]

 11 Toothed belt 12 Belt body 13 Core wire

Claims (13)

[Claims] 1. A tooth portion is formed on at least one surface,
A surface of the tooth portion is covered with a canvas, and a belt main body having core wires embedded in the longitudinal direction is provided. The belt main body is made of hydrogenated nitrile rubber having a hydrogenation rate of 91% or more. As a rubber, 1 to 3 parts of a sulfur-based vulcanizing agent, and 0.3 to 2 parts of a metal of a dialkyl dithiocarbamic acid salt formed from a metal of Group VIa of the periodic table with respect to 100 parts of the raw rubber, and 0 A toothed belt formed of a rubber to which a vulcanization accelerator containing 5 to 5 parts of a thiuram type and a sulfenamide type and a vulcanization acceleration aid are added. 2. The hydrogenation rate is 91.5-93.5%.
The toothed belt according to claim 1, wherein 3. The toothed belt according to claim 1, wherein the sulfur vulcanizing agent is at least one of powdered sulfur and insoluble sulfur. 4. The toothed belt according to claim 1, wherein the alkyl group of the metal salt of dialkyl dithiocarbamic acid is either a methyl group or an ethyl group. 5. The toothed belt according to claim 1, wherein the metal of the dialkyl dithiocarbamic acid metal salt is either selenium or tellurium. 6. The toothed belt according to claim 1, wherein the metal salt of dialkyldithiocarbamate is tellurium diethyldithiocarbamate. 7. The toothed belt according to claim 1, wherein the thiuram-based vulcanization accelerator is tetramethylthiuram disulfide and dipentamethylenethiuram tetrasulfide. 8. The sulfenamide-based vulcanization accelerator,
The toothed belt according to claim 1, wherein the toothed belt is N-cyclohexyl-2-benzothiazyl sulfenamide. 9. The toothed belt according to claim 1, wherein the vulcanization acceleration aid is zinc white. 10. The toothed belt according to claim 1, wherein the core wire is made of high-strength glass fiber. 11. The toothed belt according to claim 1, wherein the canvas is a woven cloth having nylon threads. 12. The toothed belt according to claim 1, wherein the canvas is a woven fabric having aramid yarn. 13. The toothed belt according to claim 1, wherein the canvas is a woven fabric having nylon threads and aramid threads.