JPH1194027A - Toothed belt - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a toothed belt which shows excellent abrasion resistance, cracking resistance and noiseless performance, and is remarkably improved in its life. SOLUTION: Teeth 1 are arranged in a longitudinal direction of a belt. Core wires 2 on the back side of the teeth 1 are embedded in a back portion 3. A film 4 covers the surfaces of the teeth 1 and bottoms therebetween. The back portion 3 is composed of two rubber layers. An outer layer 3a is made of rubber having modulus of 4.5 MPa or more under 100% extention. It exceeds that of rubber of an inner layer 3b by 1.0 MPa or more. The rubber of the outer layer 3a has extention of 400% or more at the time of shearing, and hardness higher than that of the inner layer 3b, by more than three degrees.

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 for an automobile engine and the like.

[0002]

2. Description of the Related Art In recent years, the operating environment temperature of a toothed belt used for transmission of rotational drive has been increasing with the increase in output and rotation of an automobile engine, and the load on the toothed belt has also been increased. Increasing. The required quality of the toothed belt used in such an automobile engine is such that the crack resistance at the root of the tooth portion, the wear resistance at the rear portion, and the crack resistance are high, and the bendability in the belt longitudinal direction is excellent. It is mentioned.

[0003] On the other hand, as rubber constituting a toothed belt,
In response to the harsher use environment, chloroprene rubber has been changed to chlorosulfonated polyethylene, and nowadays, more heat-resistant materials have been used for hydrogenated nitrile rubber. Various improvements have also been made to the core wire and the tooth cloth to improve the durability (JP-A-7-151189, JP-A-2-2085).
No. 56, etc.).

[0004] In addition, hydrogenated nitrile rubber, which is currently most widely used as a rubber for toothed belts for automobile engines, is also examined by examining its hydrogenation rate, type of crosslinking agent, and various additives. Durability has been improved. For example, JP-A-8-3374 discloses a belt using a rubber composition prepared by adding a fiberizable fluororesin containing a polyfunctional co-crosslinking agent to solid rubber.

Further, the hydrogenated nitrile rubber contains a metal salt of an unsaturated carboxylic acid to improve the abrasion resistance and crack resistance. The improved rubber is used to form the teeth and the back of the toothed belt. Japanese Patent Publication No. 5-64252, Japanese Patent Publication No.
See Japanese Patent No. 37576, Japanese Patent Publication No. 5-262914, and the like. )

[0006]

However, in the case of a toothed belt which is forced to transmit a high load, such as a toothed belt for an automobile engine, the rubber composition disclosed in the above-mentioned Japanese Patent Application Laid-Open No. 8-3374 is disclosed. The use of a material can improve the crack resistance at the root of the teeth, but when the teeth mesh with the pulley due to the high hardness of the rubber, the teeth rebound greatly due to the impact. However, there is a problem that this may contribute to the vibration of the belt and adversely affect the noise and the life of the belt. In addition, when the rubber composition provided in JP-A-8-3374 is used for the back part of a toothed belt, elongation and tensile modulus are insufficient. There is a problem that the effect as expected in crack resistance cannot be obtained, and further, there is a problem that abrasion or cracks are easily caused by contact with a tension pulley, an idler pulley, or the like.

Further, when the toothed portion and the back portion of the toothed belt are formed of the hydrogenated nitrile rubber containing a metal salt of an unsaturated carboxylic acid as described above, the abrasion of the back portion is surely reduced and Although the crack resistance of the tooth base of the tooth portion is improved, there is a problem that vibration of the belt is generated and noise is generated. The present invention has been made in view of the above points,
It is an object of the present invention to provide a toothed belt having excellent wear resistance, crack resistance, and quietness, and having significantly improved life.

[0008]

A toothed belt according to the present invention comprises a plurality of teeth 1 provided along a longitudinal direction, and a plurality of teeth 1.
In a toothed belt comprising a back part 3 having a back side core 2 embedded therein and a tooth cloth 4 covering the surface of the tooth part 1 and the bottom surface of the tooth, a rubber layer constituting the back part 3 has a two-layer structure. And the outer layer 3a of the two-layer structure has a modulus of at least 4.5 MPa at 100% elongation and at least 1.0 MPa greater than the rubber of the inner layer 3b, and an elongation at cutting of 400%.
In addition to the above, the inner layer 3b is formed of rubber having physical properties higher than that of the rubber by 3 degrees or more.

According to a second aspect of the present invention, the outer layer 3a of the rubber layer having the two-layer structure constituting the back surface portion 3 is composed of a hydrogenated nitrile rubber and an unsaturated carboxylic acid metal salt in a ratio of 98: 2 to 55: 4.
It is characterized by being formed of a rubber crosslinked by blending 0.2 to 10 parts by weight of an organic peroxide with 100 parts by weight of a polymer component mixed at a weight ratio of 5.

A third aspect of the present invention is characterized in that 5 to 50 parts by weight of carbon black and 2 to 15 parts by weight of a plasticizer are blended in addition to the organic peroxide. Further, according to the invention of claim 4, the inner layer 3a of the rubber layer having the two-layer structure constituting the back part 3 has a hydrogenation rate of 90%.
For 100 parts by weight of ~ 98% hydrogenated nitrile rubber,
It is characterized by being formed of a crosslinked rubber containing 10 to 80 parts by weight of carbon black, 2 to 15 parts by weight of a plasticizer, and 0.2 to 10 parts by weight of an organic peroxide.

The invention of claim 5 is characterized in that the tooth cloth 4 is formed of a cloth containing at least a part of an aromatic polyamide fiber.

[0012]

Embodiments of the present invention will be described below. As shown in FIG. 1, the toothed belt includes a plurality of teeth 1 provided at predetermined regular intervals along a longitudinal direction;
, A plurality of core wires 2 embedded in the back portion 3 along the longitudinal direction, and a tooth portion 1.
And a tooth cloth 4 that covers the surface of the tooth bottom and the surface of the tooth bottom between the tooth parts 1. The back portion 3 and the tooth portion 1 are formed of a rubber layer.
(Side) layer 3b.

In the present invention, as the rubber constituting the outer layer 3a of the back portion 3, a hydrogenated nitrile rubber and an unsaturated metal carboxylate are mixed in a weight ratio of 98: 2 to 55:45. A rubber crosslinked by blending 0.2 to 10 parts by weight of an organic peroxide with respect to 100 parts by weight of a polymer component, and having a modulus at 100% elongation (tensile modulus M100) of 4.5 MPa or more. In addition, a rubber having an elongation at the time of cutting of 400% or more is used.

The rubber of the outer layer 3a of the back part 3 is 100
If the modulus at the time of% elongation is less than 4.5 MPa, the rubber deformation due to stress when the toothed belt comes into contact with a tension pulley, an idler pulley, or the like becomes large.
Since the rubber cannot withstand this, the wear resistance and the crack resistance are reduced, and the life of the belt is shortened. Further, when the elongation at the time of cutting is less than 400%, cracks due to bending are easily generated, and the life of the belt is shortened. For this reason, in the present invention, as described above, a rubber having a modulus at the time of 100% elongation of 4.5 MPa or more and an elongation at the time of cutting of 400% or more is used as the rubber of the outer layer 3 a of the back surface portion 3. However, if the modulus at 100% elongation exceeds 10 MPa, it becomes difficult to adjust the elongation at cutting to 400% or more, so the upper limit of the modulus at 100% elongation is preferably set to 10 MPa. The higher the elongation at the time of cutting, the more desirable, so the upper limit is not particularly set. However, the elongation is preferably adjusted so that the modulus at 100% elongation does not fall out of the range of 4.5 to 10 MPa.

The hydrogenated nitrile rubber used for the rubber constituting the outer layer 3a of the back surface 3 must have a hydrogenation rate of at least 90% from the viewpoint of heat resistance. ~ 98% is preferred. The modulus (tensile modulus) is increased by compounding a metal salt of an unsaturated carboxylic acid with the hydrogenated nitrile rubber. In order to ensure a higher tear strength, the hydrogenated nitrile rubber and the unsaturated metal salt of a carboxylic acid are used in a proportion of 98: 2 to 5 as described above.
It is necessary to mix at a weight ratio of 5:45. The unsaturated carboxylic acid metal salt is not particularly limited, but zinc acrylate, zinc methacrylate, and the like can be used. Although it is possible to increase the modulus (tensile modulus) by reinforcing with carbon black without using a metal salt of an unsaturated carboxylic acid, the elongation at break and tear strength of rubber are reduced, and deformation and deformation of rubber are caused. It is not preferable because sufficient durability against generation of cracks due to bending cannot be provided.

The above-mentioned organic peroxide compounded in the polymer component comprising the hydrogenated nitrile rubber and the metal salt of unsaturated carboxylic acid is used as a crosslinking agent, and has a modulus (tensile strength) having the above-defined numerical value. In order to ensure elasticity) and elongation at break, the polymer component 10
It is necessary to mix 0.2 to 10 parts by weight of an organic peroxide with respect to 0 parts by weight for crosslinking. The organic peroxide is not particularly limited, but may be, for example, 1,1-di-t-butylperoxy-3,3,5-trimethylcyclohexane, di-t-butyl peroxide, dibutylcumyl peroxide. , Dicumyl peroxide, 2,
5-dimethyl-2,5-di (t-butylperoxy) hexane, 2,5-dimethyl-2,5-di (t-butylperoxy) hexyne, 1,3-bis (t-butylperoxyisopropyl) ) Benzene, t-butyl peroxyisopropyl carbonate and the like can be used. In addition to such an organic peroxide, an appropriate amount of a sulfur compound, an oxime nitroso compound, or a monomer or polymer generally used as a co-crosslinking agent may be added.

Furthermore, in addition to the above, the modulus (tensile elastic modulus) and the breaking elongation are secured to the above-specified values,
Carbon black, a plasticizer, and the like can be appropriately added within a range that ensures an appropriate tear strength. Carbon black is used in an amount of 5 to 50 parts by weight based on 100 parts by weight of a polymer component comprising a hydrogenated nitrile rubber and a metal salt of an unsaturated carboxylic acid.
It is preferable to mix 2 to 15 parts by weight of the plasticizer. As a plasticizer, trimellitic acid with excellent heat resistance,
Polyester, polyether, phthalic acid and the like can be used.

On the other hand, in the present invention, the rubber constituting the inner layer 3a of the back surface 3 is a hydrogenation rate of 90 to 98.
% Of hydrogenated nitrile rubber, 100 parts by weight of carbon black, 10 to 80 parts by weight of carbon black, 2 to 15 parts by weight of plasticizer,
A rubber cross-linked by mixing 0.2 to 10 parts by weight of an organic peroxide is used, and the tooth portion 1 is also integrally formed of the same rubber as the inner layer 3a of the back surface portion 3. .
As the plasticizer and the organic peroxide, those described above can be used.In addition to these, sulfur compounds, oxime nitroso compounds, and monomers and polymers are commonly used as co-crosslinking agents. Can be added in an appropriate amount.

Since the outer layer 3a of the back portion 3 is formed of rubber having high modulus and high hardness as described above, there is a possibility that the vibration of the belt may generate noise and shorten the life.
For this reason, by using a rubber having a lower modulus and a lower hardness than the rubber of the outer layer 3a as the rubber constituting the inner layer 3b of the back part 3, it is possible to suppress the generation of sound and the shortening of the life due to the vibration of the belt. The hardness of the rubber constituting the inner layer 3b of the back surface portion 3 is 60 to 75.
Degree (the modulus at 100% elongation is 2.5 to 6.5 MPa), and a hardness of 65 to 70 degrees is more preferable (modulus at 100% elongation is 3.
0 to 5.0 MPa). If the hardness of the rubber forming the inner layer 3a of the back surface portion 3 is less than 60 degrees, the deformation of the tooth portion 1 when the toothed belt meshes with the pulley may be increased, and the life may be shortened on the contrary. Exceeds 75 degrees, there is a possibility that sound generation due to the vibration of the belt may increase. In the present invention, the hardness of rubber is JIS K
JIS using a spring hardness meter described in 6301
It is a hardness measured according to the method specified in K6301.

By adopting the above rubber composition as the rubber constituting the inner layer 3b of the back part 3, the hardness and modulus (tensile elastic modulus) of the back part 3 are set to the rubber having the physical properties in the above ranges. The inner layer 3b can be formed. The hardness and modulus (tensile modulus) of the rubber constituting the inner layer 3b of the back surface portion 3 are set in the above ranges. In order to obtain crack resistance, the rubber constituting the outer layer 3a of the back surface 3 has a higher modulus (tensile modulus) than the rubber of the inner layer 3b.
Is set to be higher than 1.0 MPa and the hardness is higher than 3 degrees. The upper limit of the difference between the modulus (tensile elastic modulus) and the difference in hardness of the rubber of the outer layer 3a and the inner layer 3b of the back portion 3 is not particularly set. Upper limit is 7MP
The upper limit of the difference between the hardness and the hardness is preferably about 15.

As the tooth cloth 4 for covering the teeth 1 of the toothed belt, a cloth obtained by bonding a woven cloth made of an aliphatic polyamide fiber such as nylon 6, nylon 6, 6, etc. is generally used. In the present invention, it is preferable to use a woven fabric made of an aromatic polyamide fiber (aramid fiber) having a higher strength and a higher decomposition temperature than nylon and excellent in abrasion resistance. By using a woven fabric made of an aromatic polyamide fiber as the tooth cloth 4, the wear resistance and the chipping resistance of the tooth portion 1 can be improved. The aromatic polyamide fiber does not need to be 100% woven fabric, and it is sufficient if a part of the woven fabric is formed of aromatic polyamide fiber, but the aromatic polyamide fiber is used as the warp or weft exposed on the surface. It is preferable to use it, and when the aromatic polyamide fiber is used in an amount of 50% or more, the effect is remarkably increased. As the aromatic polyamide fiber, polyparaphenylene terephthalamide, polymetaphenylene isophthalamide, polyparaphenylene-3,4-diphenylether terephthalamide and the like can be used.

As the cord 2 for reinforcing the toothed belt, a cord obtained by twisting and bonding glass fibers is generally used, but a cord formed from an aromatic polyamide fiber can also be used. . In manufacturing the toothed belt, first, the tooth cloth 4 is finished into an endless cylindrical body, which is set in a mold, and the core wire 2 is spirally wound around the outer periphery thereof at a constant rate. And a sheet of the rubber composition for the outer layer 3a is further wound thereon. Then, by heating and pressurizing and vulcanizing this, a cylindrical vulcanized molded product is formed, and then the cylindrical molded product is cut into ring-shaped sections, whereby a toothed belt can be obtained.
In this way, it is possible to obtain a toothed belt in which the rubber of the back part 3 has a two-layer structure of the outer layer 3a and the inner layer 3b, and the tooth part 1 is formed by the rubber of the inner layer 3b. However, during molding, as shown in FIG.
A portion of the rubber a also bites into the tooth portion 1.

In the toothed belt shown in FIG. 2, the back portion 3 is formed so as to have a two-layer structure in which the outer layer 3a and the inner layer 3b are divided by a plane. The toothed belt having such a structure is formed by first forming the inner layer 3a of the back portion 3 and the tooth portion 1 and then laminating the outer layer 3b of the back portion 3 and forming and vulcanizing the layer. Obtainable.

[0024]

Next, the present invention will be described specifically with reference to examples. (Blending of Rubber Constituting Layer 3a Outside Back Side 3) Table 1
The rubber composition 3a-1, 3a was kneaded for about 4 minutes using a Banbury mixer
-2, 3a-3 and 3a-4 were obtained.

The obtained rubber compositions 3a-1, 3a-
2,3a-3 and 3a-4 are rolled with open rolls,
Press vulcanization was performed at 65 ° C. for 30 minutes to obtain a vulcanized rubber sheet. JIS K 6301 for this vulcanized rubber sheet
A tensile test, a tear test, and the like were performed in accordance with the above, and physical properties were measured. Table 1 shows the results.

[0026]

[Table 1]

(Blending of Rubber Constituting Inner Layer 3b of Back Side Part 3 and Tooth Part 1) The rubber composition 3b- is kneaded for about 4 minutes using a Banbury mixer. 1, 3b-2, 3b-3, 3b-4 were obtained. The obtained rubber composition 3b-1, 3b-2, 3b
-3, 3b-4 was rolled with an open roll and press-vulcanized at 165 ° C. for 30 minutes to obtain a vulcanized rubber sheet. The vulcanized rubber sheet was subjected to a tensile test, a tear test, and the like according to JIS K6301, and the physical properties were measured. Table 2 shows the results.

[0028]

[Table 2]

(Tooth cloth 4) A woven cloth produced using the fibers shown in Table 3 for the warp and the weft was used as the tooth cloths 4-1 and 4-2.

[0030]

[Table 3]

(Manufacture of toothed belt)
4-2 is finished into an endless cylindrical body, which is set in a mold, and two core wires 2 made of S-twisted glass fiber and Z-twisted glass fiber are alternately arranged at a pitch of 1.45 mm from the outer periphery thereof. It winds up so that it may be arrange | positioned, and the sheet | seat of the rubber composition 3b-1, 3b-2, 3b-3, 3b-4 of Table 2 on this further, and also the rubber composition 3a-1 of Table 1 on it further 3
Sheets a-2, 3a-3, and 3a-4 were wound. Thereafter, this is subjected to a normal press-fitting method (160 ° C. for 3 hours).
(Vulcanization under pressure for 0 minutes and molding) to obtain a vulcanized molded article in a cylindrical shape. Then, by cutting this cylindrical molded product into round slices, as shown in FIG. 1, 105S8M19 (tooth shape S8M, number of teeth 105, 105S8M19) of Examples 1-4 and Comparative Examples 1-5.
A toothed belt having a width of 19.1 mm and a tooth pitch of 8.000 mm) was obtained. The two types of rubber sheets shown in Tables 1 and 2 can be used by being bonded in advance.

Table 4 shows combinations of the materials of Examples 1 to 4 and Comparative Examples 1 to 5. Further, the physical properties and running performance of the toothed belts obtained in Examples 1 to 4 and Comparative Examples 1 to 5 were measured, and the results are shown in Table 4. The measurement of the tooth shearing force was performed using the jig 10 of FIG. 3 and tightening the toothed belt A in the vertical direction at 9.8 N · cm per 1 mm of the belt width, and then measuring 50 m.
Pulling was performed in the upward arrow direction at a pulling speed of m / min, and the shearing force of the tooth portion 1 was measured.
In FIG. 3, reference numeral 11 denotes a tightening bolt, and 12 denotes a claw that meshes with the tooth portion 1 of the toothed belt A.

The running time test of the running performance is as follows.
Performed at an ambient temperature of 100 ° C. using the test machine of FIG.
The life is defined as the time when the function as a toothed belt such as the rubber crack on the back part 3 and the crack at the root of the tooth part 1 cannot be fulfilled, and the running time up to that point is shown in Table 4.
In FIG. 4, reference numeral 13 denotes a drive pulley having 24 teeth (6000r
pm), 14 is a driven pulley having 48 teeth, 15 is 48 teeth
Is a driven pulley having a diameter of 50 mm, and 17 is an auto tensioner having a diameter of 50 mm.

The pronunciation test is carried out by collecting sound with the microphone 18 when the toothed belt A is run using the tester shown in FIG. The higher the numerical value, the quieter the sound, and a value of 4.0 or more is a pass level. In FIG. 5, reference numeral 19 denotes a drive pulley having 24 teeth (3000 rpm),
Reference numeral 20 denotes a driven pulley having 48 teeth, and reference numeral 21 denotes a 50 mmφ tension pulley.

[0035]

[Table 4]

[0036]

As described above, according to the present invention, a plurality of teeth are provided along the longitudinal direction, a back surface in which the core wire on the back side of the teeth is buried, a surface of the teeth and a surface of the tooth bottom. In a toothed belt made of a tooth cloth for covering a rubber layer, a rubber layer constituting a back portion is formed in a two-layer structure, and an outer layer of the two-layer structure is
The modulus at% elongation is 4.5 MPa or more and 1.0 MPa or more larger than the rubber of the inner layer, the elongation at cutting is 400% or more, and the hardness is 3 degrees or more higher than the rubber of the inner layer. Since it is made of rubber having physical properties, the outer layer of the back part is formed of high modulus and high hardness rubber, and the inner layer of the back part is formed of low modulus and low hardness rubber. And the wear resistance and crack resistance can be increased by the outer layer on the back,
The silence and the life can be improved by the inner layer on the back side.

According to a second aspect of the present invention, the outer layer of the rubber layer having a two-layer structure constituting the back portion is made of a hydrogenated nitrile rubber and an unsaturated metal carboxylate in a weight of 98: 2 to 55:45. The composition having the physical properties of claim 1 and having a physical property of claim 1, wherein 0.2 to 10 parts by weight of an organic peroxide is blended with 100 parts by weight of the polymer component mixed in a ratio, thereby forming a crosslinked rubber. The outer layer of the rubber can be formed.

According to a third aspect of the present invention, 5 to 50 parts by weight of carbon black and 2 to 15 parts by weight of a plasticizer are blended in addition to the organic peroxide.
High modulus and tear strength can be ensured as physical properties of the rubber in the outer layer of the back portion. According to the invention of claim 4, the inner layer of the rubber layer having the two-layer structure constituting the back portion is formed by adding carbon black 10 to 100 parts by weight of hydrogenated nitrile rubber having a hydrogenation rate of 90 to 98%.
80 parts by weight, 2 to 15 parts by weight of a plasticizer, and 0.1 part of an organic peroxide.
Since 2 to 10 parts by weight are blended to form a crosslinked rubber, the rubber having the hardness and modulus required for quietness and long life can be used to form the rubber inside the back layer. You can do it.

According to the invention of claim 5, the tooth cloth is made of a cloth containing at least a part of aromatic polyamide fiber, so that the aromatic polyamide fiber has high strength and high decomposition temperature and has high durability. It is excellent in abrasion resistance, and can improve abrasion resistance and tooth chipping resistance of a tooth portion.

[Brief description of the drawings]

FIG. 1 shows an example of an embodiment of the present invention,
(A) is a partially broken perspective view, and (b) is a partial cross-sectional view.

FIG. 2 is a partial cross-sectional view showing another example of the embodiment of the present invention.

FIG. 3 is a front view showing a belt shearing force measuring jig.

FIG. 4 is a schematic view of an apparatus used for a running test.

FIG. 5 is a schematic diagram of an apparatus used for sound measurement.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Tooth part 2 Core wire 3 Back part 3a Outer layer 3b Inner layer 4 Tooth cloth

Continuation of front page (72) Inventor Toshiyuki Oya 4-1-1-21 Hamazoedori, Nagata-ku, Kobe-shi, Hyogo Mitsuboshi Belting Co., Ltd.

Claims (5)

[Claims] 1. A tooth comprising a plurality of tooth portions provided along a longitudinal direction, a back portion in which a core wire on the back side of the tooth portion is embedded, and a tooth cloth covering the surface of the tooth portion and the surface of the tooth bottom. In the attached belt, the rubber layer constituting the back portion is formed in a two-layer structure, and the outer layer of the two-layer structure has a modulus at the time of 100% elongation of 4.5 MPa or more and is 1.
A toothed belt formed of rubber having a physical property of not less than 0 MPa, an elongation at the time of cutting of not less than 400%, and a hardness of not less than 3 degrees higher than that of an inner layer rubber. 2. A polymer component in which a hydrogenated nitrile rubber and a metal salt of an unsaturated carboxylic acid are mixed in a weight ratio of 98: 2 to 55:45, wherein the outer layer of the rubber layer having a two-layer structure constituting the back surface is formed. Organic peroxide 0.2 to 1 per 100 parts by weight
2. The toothed belt according to claim 1, wherein the belt is formed of a crosslinked rubber containing 0 parts by weight. 3. The toothed belt according to claim 2, wherein 5 to 50 parts by weight of carbon black and 2 to 15 parts by weight of a plasticizer are blended in addition to the organic peroxide. 4. A layer inside the rubber layer having a two-layer structure constituting a back surface portion, wherein carbon black is 10 to 80 parts by weight with respect to 100 parts by weight of hydrogenated nitrile rubber having a hydrogenation rate of 90 to 98%.
Parts by weight, plasticizer 2 to 15 parts by weight, organic peroxide 0.2 to
The toothed belt according to any one of claims 1 to 3, wherein the belt is formed of a rubber crosslinked by blending 10 parts by weight. 5. The toothed belt according to claim 1, wherein the toothed cloth is made of a cloth containing at least a part of an aromatic polyamide fiber.