JP2022116915A - friction transmission belt - Google Patents

Abstract

To provide a friction transmission belt excellent in abrasion resistance.SOLUTION: A friction transmission belt has a compression layer constituting a pulley contact part. The compression layer includes an inner layer composed of a rubber composition, and an outer layer composed of a fiber member provided on a pulley contact side of the inner layer. The rubber composition has a 10% compression stress M10 in a belt width direction or 2.0 MPa or more.SELECTED DRAWING: Figure 1

Description

The present invention relates to friction transmission belts.

Conventionally, as means for transmitting rotational power of an engine, a motor, etc., a pulley or the like is fixed to the rotating shaft of the driving side and the driven side, and a transmission belt such as a V-ribbed belt or V-belt is stretched over each pulley. methods are widely used.
When such a transmission belt is wound around pulleys and used, in order to maintain the pulley contact part in a state of low friction coefficient and improve wear resistance, for example, in a V-ribbed belt, the V-ribbed surface is Covering with a reinforcing cloth is performed (see, for example, Patent Documents 1 to 3).

Japanese Patent Publication No. 2-42344 JP-A-2002-122187 JP-A-2002-5238

Improvement in abrasion resistance of friction transmission belts is a property that is usually required, and this requirement will never disappear.
In the V-ribbed belts described in Patent Documents 1 to 3, the abrasion resistance is improved by devising the structure of the reinforcing cloth and its surroundings.

The inventors of the present invention conducted intensive studies to improve the wear resistance of a friction transmission belt, and found a friction transmission belt with excellent wear resistance based on a new idea different from Patent Documents 1 to 3, and the present invention. completed.

The friction transmission belt of the present invention is a friction transmission belt having a compression layer forming a pulley contact portion,
The compression layer includes an inner layer made of a rubber composition and an outer layer made of a fiber member provided on the pulley contact side of the inner layer,
The rubber composition has a stress M10 at 10% compression in the belt width direction of 2.0 MPa or more.
The friction transmission belt has excellent wear resistance because the stress M10 at 10% compression in the belt width direction of the rubber composition constituting the inner layer of the compression layer is as large as 2.0 MPa or more.

In the friction transmission belt, the rubber composition preferably has a stress M5 at 5% compression in the belt width direction of 1.2 MPa or more.
In this case, the abrasion resistance of the friction transmission belt is further improved.

The friction transmission belt is preferably a V-ribbed belt.
The V-ribbed belt provided with the compression layer described above exhibits good wear resistance, with the bottom of the rib being less likely to wear due to contact when meshing with the pulley.

The friction transmission belt of the present invention has excellent wear resistance.

FIG. 1 is a diagram schematically showing part of a V-ribbed belt according to one embodiment of the present invention. FIG. 3 is a diagram illustrating a method of evaluating properties of a rubber composition that constitutes a compression rubber layer of a V-ribbed belt; It is a figure which shows about the manufacturing method of a V-ribbed belt. It is a figure which shows about the manufacturing method of a V-ribbed belt. It is a figure which shows the pulley layout of the belt running test machine in an abrasion resistance test.

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described with reference to the drawings.
(V-ribbed belt)
FIG. 1 is a diagram schematically showing part of a V-ribbed belt B according to one embodiment of the present invention.
This V-ribbed belt B is used, for example, in an accessory drive belt transmission device provided in the engine room of an automobile, and has a belt circumference of 700 to 3000 mm, a belt width of 10 to 36 mm, and a belt thickness of 3.5 to 3.5 mm. It is formed to 5.0 mm.

This V-ribbed belt B has a belt body 10 composed of a double layer of an adhesive rubber layer 11 on the belt outer circumference side and a compression rubber layer 12 on the belt inner circumference side. A back rubber layer 17 is pasted on the belt outer peripheral surface of the belt body 10 . A rib-side reinforcing cloth 14 made of a knitted fabric (knit), which is a fiber member, is provided on the rib-side surface of the belt body 10 . In addition, core wires 16 are embedded in the adhesive rubber layer 11 so as to form a spiral having a pitch in the belt width direction.
In this V-ribbed belt B, the compression layer of the friction transmission belt is composed of the compression rubber layer 12 and the rib-side reinforcing cloth 14 provided on the outside of the compression rubber layer 12, and this compression layer contacts the pulley on the inner circumference side of the belt. make up the part.
Each component will be described below.

The adhesive rubber layer 11 is formed in a belt-like shape with a horizontally long rectangular cross section and has a thickness of 0.8 to 2.5 mm, for example. The adhesive rubber layer 11 is formed using an uncrosslinked rubber composition in which various compounding agents are blended with the raw rubber component.

The rubber composition constituting the adhesive rubber layer 11 includes raw rubber components such as ethylene-α-olefin elastomers such as ethylene-propylene rubber (EPR) and ethylene-propylene diene monomer rubber (EPDM), chloroprene rubber (CR), Chlorosulfonated polyethylene rubber (CSM), hydrogenated acrylonitrile rubber (HNBR) and the like are used. Among these, ethylene-α-olefin elastomers are preferred from the viewpoint of exhibiting excellent properties in terms of heat resistance and cold resistance.

Compounding agents used in the adhesive rubber layer 11 include, for example, cross-linking agents (eg, sulfur, organic peroxides), vulcanization accelerators, co-cross-linking agents, anti-aging agents, processing aids, plasticizers, carbon black, and the like. reinforcing materials, fillers, and the like. The rubber composition forming the adhesive rubber layer 11 may contain short fibers. The rubber composition forming the adhesive rubber layer 11 is obtained by blending a raw rubber component with a compounding agent, kneading the uncrosslinked rubber composition, and heating and pressurizing it to crosslink it with a crosslinking agent.

The core wire 16 is embedded in the adhesive rubber layer 11 so as to extend in the length direction of the belt and form a spiral having a pitch in the width direction of the belt. The cord 16 is made of twisted yarn 16' such as polyester fiber, polyethylene naphthalate (PEN) fiber, aramid fiber, vinylon fiber, polyketone fiber, or the like. The core wire 16 has an outer diameter of, for example, 0.7 to 1.1 mm. In order to impart adhesiveness to the belt body 10, the core wire 16 is subjected to an adhesion treatment in which it is immersed in an RFL aqueous solution and then heated, and/or an adhesion treatment in which it is immersed in rubber glue and then dried. ing.

A plurality of V-ribs 13 are provided on the compression rubber layer 12 so as to hang down toward the inner circumference of the belt. Each of the plurality of V-ribs 13 is formed in the shape of a protrusion extending in the length direction of the belt and having a substantially triangular cross section, and is arranged side by side in the width direction of the belt. Each V-rib 13 has, for example, a rib height of 2.0 to 3.0 mm and a base-to-end width of 1.0 to 3.6 mm. Also, the number of ribs is, for example, 3 to 10 (the number of ribs is 6 in FIG. 1).

The compression rubber layer 12 is made of a rubber composition having predetermined compression characteristics. Therefore, it has exceptional wear resistance.
Specifically, the rubber composition forming the compression rubber layer 12 has a 10% compression stress M10 in the belt width direction of the V-ribbed belt B (hereinafter also referred to as width direction M10) of 2.0 MPa or more. Thereby, the V-ribbed belt B has good abrasion resistance.

The V-ribbed belt B wound around the pulley normally travels while being compressed in the width direction. In addition, if the compression rubber layer 12 of the V-ribbed belt B is a member that is likely to be compressed and deformed in the width direction, the rib portion of the V-ribbed belt B will enter deeply into the grooves of the rib pulleys during running, and the rib bottom of the V-ribbed belt B will be deformed. It becomes easier to be pressed against the rib pulley.
On the other hand, the V-ribbed belt B having the width direction M10 of 2.0 MPa or more can avoid excessive contact surface pressure between the rib bottom and the rib pulley during running. Therefore, the V-ribbed belt B having the width direction M10 of 2.0 MPa or more has good abrasion resistance.

The width direction M10 is preferably 3.0 MPa or more from the viewpoint of better wear resistance.
On the other hand, although the upper limit of the width direction M10 is not particularly limited, it is preferably 10.0 MPa. If the width direction M10 is too large, the flexibility in the length direction is impaired and the belt may be damaged early.

The rubber composition constituting the compression rubber layer 12 preferably has a stress M5 at 5% compression in the belt width direction of the V-ribbed belt B (hereinafter also referred to as width direction M5) of 1.2 MPa or more. In this case, the ribbed belt B has better wear resistance.
The width direction M5 of the V-ribbed belt B is more preferably 1.4 MPa or more, still more preferably 1.6 MPa or more, and particularly preferably 2.0 MPa or more, in order to improve abrasion resistance.

Although the upper limit of the width direction M5 is not particularly limited, it is preferably 7.0 MPa. If the width M5 is too large, the flexibility in the length direction is impaired, and the belt may be damaged early.

The compression characteristics (stress during compression) of the rubber composition forming the compression rubber layer 12 are evaluated by the following method.
FIGS. 2(a) to 2(d) are diagrams for explaining a technique for evaluating the compression characteristics of the rubber composition forming the compression rubber layer 12. FIG.

First, one rib portion 21 is cut out from a V-ribbed belt 20 having a plurality of rib portions (see FIG. 2(a)) (see FIG. 2(b)). After that, a strip-shaped test piece 22 is cut out from one rib portion (see FIG. 2(c)). In this case, the test piece 22 is cut out, for example, from the shaded area in FIG. 2(a).
The test piece 22 is a rectangular parallelepiped test piece having a thickness T of 0.5 to 1 mm, a height H of 1.9 to 2.0 mm, and a length L of 1.9 to 2.0 mm. This test piece 22 is cut out so that the longitudinal direction of the test piece 22 coincides with the longitudinal direction of the V-ribbed belt 20 .
Next, a compression test is performed by compressing the test piece 22 in the thickness direction, and the load (MPa) at 5% compression and the load (MPa) at 10% compression are measured.

In the compression test, the test piece 22 was attached to the tester, and the compression test was performed under the conditions of an experimental temperature of 23 ± 2 ° C. and a compression rate of 1 mm / min, and the load at 5% compression and the load at 10% compression. to measure Here, as the testing machine, a testing machine capable of performing a compression test, such as a universal testing machine, may be used.

After that, each of the measured load at 5% compression and load at 10% compression is divided by the cross-sectional area (height H × length L) of the compression pressing surface 23 of the test piece 22, and the obtained value be the stress at 5% compression (width direction M5) and the stress at 10% compression (width direction M10).

The rubber composition forming the compression rubber layer 12 preferably has the following tensile properties.
The ratio of the M10 elastic modulus in the longitudinal direction to the M50 elastic modulus in the longitudinal direction of the V-ribbed belt B (M10 elastic modulus/M50 elastic modulus) is preferably 1.5 or more, and preferably 2.0 or more. more preferred. Satisfying these requirements is more suitable for ensuring good abrasion resistance of the V-ribbed belt B.
In addition, the V-ribbed belt B in which the M10 elastic modulus/M50 elastic modulus is 2.0 or more has excellent crack resistance.
The upper limit of the M10 elastic modulus/M50 elastic modulus is usually about 5.0.

The rubber composition constituting the V-ribbed belt B preferably has a stress M50 at 50% elongation in the belt longitudinal direction (hereinafter also referred to as length direction M50) of 10 Mpa or less, more preferably 7 Mpa or less. This is because it is more suitable for improving the crack resistance of the V-ribbed belt B.
Although the lower limit of the length direction M50 is not particularly limited, it is usually about 1.5 MPa.

The rubber composition constituting the V-ribbed belt B preferably has a stress M10 at 10% elongation in the belt longitudinal direction (hereinafter also referred to as length direction M10) of 2.0 MPa or more, and is 2.5 MPa or more. is more preferable. This is because it is more suitable for improving the abrasion resistance of the V-ribbed belt B.
Although the upper limit of the length direction M10 is not particularly limited, it is usually about 7.0 MPa.

The tensile properties of the rubber composition forming the compression rubber layer 12 are evaluated by the following method. FIG. 2(e) is a diagram for explaining a technique for evaluating the tensile properties of the rubber composition that constitutes the compression rubber layer 12. As shown in FIG.
First, a test piece for evaluation is produced. This test piece is prepared in the same manner as the test piece 22 for evaluating the compressive properties described above, but is a rectangular parallelepiped test piece 122 with a length L of 50 mm (see FIG. 2(e)). The specimen 122 is marked with two gauge lines 124 on one of the faces 123 with the largest area. Here, the two marked lines 124 are marked at the center of the surface 123 having the maximum area of the test piece 122 so that the distance between the marked lines is 10 mm.
Next, a tensile test is performed by pulling the test piece 122 in the length direction, and the load (MPa) at 10% elongation and the load (MPa) at 50% elongation are measured.

In the tensile test, the test piece 122 was attached to the tester, and the tensile test was performed under the conditions of an experimental temperature of 23 ± 2 ° C and a tensile speed of 500 mm / min, and the load at 10% elongation and the load at 50% elongation to measure Here, as the testing machine, a testing machine capable of performing a compression test, such as a universal testing machine, may be used.
After that, each of the measured load at 10% elongation and load at 50% elongation is divided by the cross-sectional area (thickness T × height H) of the test piece 122, and the obtained value is the stress at 10% elongation. (length direction M10) and stress at 50% elongation (length direction M50).
Further, the length direction M10 and the length direction M50 are respectively divided by the elongation amount (%) of each stress, and the obtained values are defined as the M10 elastic modulus and the M50 elastic modulus, respectively.
Furthermore, the ratio of the M10 elastic modulus to the M50 elastic modulus (M10 elastic modulus/M50 elastic modulus) is calculated.

The compression rubber layer 12 is formed using an uncrosslinked rubber composition (raw material composition) in which various compounding agents are blended with the raw rubber component.

Examples of raw rubber components of the rubber composition constituting the compression rubber layer 12 include ethylene-α-olefin elastomers such as ethylene-propylene rubber (EPR) and ethylene-propylene diene monomer rubber (EPDM), chloroprene rubber (CR), Chlorosulfonated polyethylene rubber (CSM), hydrogenated acrylonitrile rubber (H-NBR) and the like. Among these, ethylene-α-olefin elastomers are preferred from the viewpoint of exhibiting excellent properties in terms of heat resistance and cold resistance.

Compounding agents used in the compression rubber layer 12 include, for example, cross-linking agents (eg, sulfur, organic peroxides), vulcanization accelerators, co-cross-linking agents, anti-aging agents, processing aids, plasticizers, carbon black, and the like. Examples include reinforcing materials, fillers, short fibers, and the like. The rubber composition that constitutes the compression rubber layer 12 is obtained by blending a compounding agent with the raw rubber component, kneading the uncrosslinked rubber composition, and heating and pressurizing it to crosslink it with a crosslinking agent.

The raw material composition for forming the compression rubber layer 12 preferably contains an unsaturated carboxylic acid metal salt as a compounding agent.
The amount of the unsaturated carboxylic acid metal salt compounded is preferably 1 to 40 parts by mass with respect to 100 parts by mass of the raw rubber component. It is suitable for setting the width direction M10 of the rubber composition forming the compression rubber layer 12 to 2.0 MPa or more.

The unsaturated carboxylic acid metal salt is composed of an unsaturated carboxylic acid and a metal. Examples of the unsaturated carboxylic acid include unsaturated monocarboxylic acids such as acrylic acid and methacrylic acid, unsaturated dicarboxylic acids such as maleic acid, fumaric acid and itaconic acid, monomethyl maleate and monoethyl itaconate.
The metal is not particularly limited as long as it forms a salt with an unsaturated carboxylic acid, but beryllium, magnesium, calcium, strontium, barium, titanium, chromium, molybdenum, manganese, iron, cobalt, nickel, copper, and silver. , zinc, cadmium, aluminum, tin, lead, mercury, antimony, etc. can be used.
Among these, zinc diacrylate or zinc dimethacrylate is preferred.

The uncrosslinked rubber composition for forming the compression rubber layer 12 may contain at least an ethylene-α-olefin elastomer as a raw rubber material, a crosslinking agent, carbon black, and an unsaturated carboxylic acid metal salt. preferable. An uncrosslinked rubber composition having such a composition is particularly suitable for forming a rubber composition having a width direction M10 of 2.0 Mpa or more.
At this time, the cross-linking agent preferably contains at least sulfur, and the amount of sulfur compounded is preferably 1 to 5 parts by mass with respect to 100 parts by mass of the raw rubber component.

The adhesive rubber layer 11 and the compression rubber layer 12 may be composed of different rubber compositions, or may be composed of exactly the same rubber composition.

The back rubber layer 17 is formed using the same raw material composition as that of the adhesive rubber layer 11, which consists of raw rubber components and compounding agents. However, the back rubber layer 17 is preferably composed of a rubber composition that is slightly harder than the adhesive rubber layer 12 from the viewpoint of suppressing adhesion due to contact between the back surface of the belt and the flat pulley.
Also, the thickness of the back rubber layer 17 is, for example, 0.4 mm to 0.8 mm. The texture of the woven fabric may be transferred to the surface of the back rubber layer 17 from the viewpoint of suppressing the noise generated between the back surface of the belt and the flat pulley with which the back surface of the belt is in contact.

In addition, it is also possible to use a back side reinforcing cloth instead of the back rubber layer 17 . In this case, the back-side reinforcing cloth is composed of a cloth material, a knitted fabric, a non-woven fabric, etc. woven in plain weave, twill weave, satin weave, etc., using yarns such as cotton, polyamide fiber, polyester fiber, and aramid fiber, for example. In order to impart adhesiveness to the belt body, the back side reinforcing cloth is subjected to an adhesion treatment by immersing it in an RFL aqueous solution and heating it before molding, and / or coating the surface that will be the belt body 10 side with rubber paste. A drying adhesive treatment is applied.

The rib-side reinforcing cloth 14 is, for example, a woolly processed yarn obtained by false twisting (woolly processing) polyamide fiber, polyester fiber, cotton, nylon fiber, or the like, or a polyurethane elastic yarn as a core yarn and covered with a covering yarn. It is a knitted fabric made of ringed covering yarn or the like.

The fiber surface of the rib-side reinforcing fabric 14 may be covered with an RFL layer. The RFL coating may contain dispersed coefficient of friction reducing agents. Examples of friction coefficient reducing agents include polytetrafluoroethylene (PTFE), tetrafluoroethylene/ethylene copolymer (ETFE), and tetrafluoroethylene/perfluoroalkyl vinyl ether copolymer (PFA). Among these, polytetrafluoroethylene particles, which are most effective in reducing the friction coefficient, are preferably blended as the friction coefficient-lowering agent.

If the rib-side reinforcing cloth 14 is surface-coated with the RFL coating containing the friction coefficient reducing agent, dust and rust will not reach the inside of the rib-side reinforcing cloth 14 even when used in an environment where dust and rust are generated. can maintain a low coefficient of friction.
The rib-side reinforcing cloth 14 has a thickness of, for example, 0.2 to 1.0 mm.

Next, a method for manufacturing the V-ribbed belt B will be described with reference to FIGS. 3 and 4. FIG.
In this method of manufacturing the V-ribbed belt B, a belt forming device 30 is used.
This belt molding device 30 comprises a cylindrical rubber sleeve mold 31 and a cylindrical outer mold 32 to which it is fitted.

The rubber sleeve mold 31 is made of, for example, acrylic rubber and is flexible. can be made The outer peripheral surface of the rubber sleeve mold 31 has a shape for forming, for example, the back side of the V-ribbed belt B smoothly.
The rubber sleeve mold 31 has, for example, an outer diameter of 700-2800 mm, a thickness of 8-20 mm, and a height of 500-1000 mm.

The cylindrical outer mold 32 is, for example, made of metal, and on the inner surface thereof, a ridge 32a having a substantially triangular cross section for forming the V ribs 13 of the V-ribbed belt B extends in the circumferential direction and in the height direction. They are arranged side by side. For example, 140 protrusions 32a are arranged in the height direction. The cylindrical outer mold 32 has, for example, an outer diameter of 830 to 2930 mm, an inner diameter (not including the ridges 32a) of 730 to 2830 mm, a height of 500 to 1000 mm, and a height of the ridges 32a of 2.0 to 2.0 mm. 2.5 mm, and the width of each ridge portion 32a is 3.5 to 3.6 mm.

In the manufacturing method of the V-ribbed belt B, first, the belt materials, that is, the adhesive rubber material 11', which is an uncrosslinked rubber sheet for forming the adhesive rubber layer 11, the compressed rubber layer 12, and the back rubber layer 17, and the compressed rubber material. 12', back rubber material 17', knitted fabric 14' for forming rib-side reinforcing fabric 14, and twisted thread 16' for forming core wire 16 are prepared.

The adhesive rubber material 11' is obtained by kneading the raw material rubber of the adhesive rubber layer 11 and compounding agents in a kneader to obtain an uncrosslinked rubber composition in the form of a mass. It is manufactured by processing into a sheet of ~0.8 mm.

The compression rubber material 12' is obtained by kneading the raw material rubber of the compression rubber layer 12 and compounding agents in a kneader to obtain an uncrosslinked rubber composition in the form of a block, which is then rolled to a thickness of, for example, 0.6 using a calender roll. It is produced by processing it into a sheet of ~1.0 mm.

The back rubber material 17' is obtained by kneading the raw material rubber of the back rubber layer 17 and compounding agents in a kneader to obtain an uncrosslinked rubber composition in the form of a block, which is then milled to a thickness of 0.4, for example, by using a calender roll. It is manufactured by processing into a sheet of ~0.8 mm.

As the knitted cloth 14' for forming the rib-side reinforcing cloth 14, an adhesion treatment of heating after being impregnated with an RFL aqueous solution, and a treatment of applying rubber paste to one side of the knitted cloth 14' to provide a rubber paste layer. Use what you have.

The RFL aqueous solution for treating the knitted fabric 14' is a mixture of precondensate of resorcinol and formalin mixed with latex. The solid content of the RFL aqueous solution is, for example, 10 to 30% by mass. The molar ratio of resorcin (R) and formalin (F) is, for example, R/F=1/1 to 1/2. Latexes include, for example, ethylene propylene diene monomer rubber latex (EPDM), ethylene propylene rubber latex (EPR), chloroprene rubber latex (CR), chlorosulfonated polyethylene rubber latex (CSM), hydrogenated acrylonitrile rubber latex (X-NBR ) and the like. The mass ratio of the precondensate (RF) of resorcinol and formalin to the latex (L) is, for example, RF/L=1/5 to 1/20. This RFL aqueous solution contains a friction coefficient reducing agent such as polytetrafluoroethylene (PTFE), for example, in an amount of 10 to 50 parts by mass per 100 parts by mass of the RFL solid content.

After the knit cloth 14' is immersed in this RFL aqueous solution, it is dried by heating at 120 to 170° C. using a drying oven, whereby the moisture in the RFL aqueous solution scatters and the condensation reaction between resorcin and formalin progresses to the knit cloth. An RFL layer is formed to cover the surface of 14'. The RFL layer has an adhesion amount of, for example, 5 to 30 parts by weight with respect to 100 parts by weight of the knitted fabric 14'.
The knitted cloth 14' treated in this manner can be easily set in the rubber sleeve mold 31 when formed into a tubular shape by a known method.

Next, the belt materials are sequentially set on the rubber sleeve mold 31 . After the sheet-like back rubber material 17' is wound around the rubber sleeve mold 31, the sheet-like adhesive rubber material 11' is wound and a plurality of strands 16' are wound so as to extend in the circumferential direction. At this time, the twisted thread 16 ′ is wound so as to form a spiral having a pitch in the height direction of the rubber sleeve mold 31 . Next, the sheet-like adhesive rubber material 11' is wound over the twisted thread 16', and the sheet-like compression rubber material 12' is further wound. Then, a tubular knitted cloth 14' is fitted over the compression rubber material 12'. At this time, as shown in FIG. 3, from the rubber sleeve mold 31, the backing rubber material 17', the adhesive rubber material 11', the thread 16', the adhesive rubber material 11', the compression rubber material 12', and the knit cloth are formed in this order. 14' are laminated. Further, a cylindrical outer mold 32 is attached to the outside of them.

Subsequently, in a state where the cylindrical outer mold 32 is attached to the rubber sleeve mold 31 , for example, high-temperature steam is sent to the rubber sleeve mold 31 to apply heat and pressure to inflate the rubber sleeve mold 31 to form the cylindrical outer mold 32 . The rubber sleeve mold 31 and the cylindrical outer mold 32 sandwich the belt material. At this time, the belt material has a temperature of, for example, 150 to 180.degree. Therefore, as the rubber component flows, the cross-linking reaction progresses, the adhesion reaction of the knit cloth 14' and the twisted yarn 16' to the rubber component also progresses, and furthermore, the inside of the cylindrical outer mold 32, which is the V-rib 13 forming portion, A V-groove between the V-ribs 13 is formed by the side projections 32a. Thus, a V-ribbed belt slab (belt main body precursor) is formed.

Finally, the V-ribbed belt slab is cooled before it is removed from the belt former 30 . Then, the removed V-ribbed belt slab is cut into round pieces having a width of, for example, 10.68 to 28.48 mm, and each piece is turned over. A V-ribbed belt B is thus obtained.

According to the manufacturing method described above, the cross-linking reaction of the uncross-linked rubber component of the V-ribbed belt B, the adhesion reaction between the rubber component and the fiber component, and the molding of the V-ribs 13 can be performed simultaneously, and the belt can be easily manufactured. can.

In this embodiment, the knitted cloth 14' formed into a cylindrical shape is fitted to the rubber sleeve mold 31 and set. You may do so.
Also, the sheet-like back rubber material 17', the adhesive rubber material 11', and the compression rubber material 12' were wound around the rubber sleeve mold 31 and set. You may

Further, the belt forming apparatus 30 has been described as having V grooves for forming the V ribs 13 of the V ribbed belt B on the inner surface of the cylindrical outer mold 32, but it is not limited to this. For example, the outer peripheral surface of the rubber sleeve mold is provided with ridges for forming the V ribs 13 of the V-ribbed belt B, and the inner peripheral surface of the cylindrical outer mold 32 is smoothed to form the back surface of the V-ribbed belt B. It may be provided. In this case, the knitted cloth 14', the compressed rubber material 12', the adhesive rubber material 11', the thread 16', the adhesive rubber material 11', and the back rubber material 17' are wound around the rubber sleeve mold 31 in this order.

Although the V-ribbed belt has been described as the friction transmission belt according to the embodiment of the present invention, the friction transmission belt according to the embodiment of the present invention is not limited to this, and may be a V-belt or the like.

EXAMPLES The present invention will be described in more detail with reference to examples below, but the present invention is not limited to the following examples.

V-ribbed belts of Examples 1 to 5 and Comparative Examples 1 and 2 were produced and evaluated.
Table 1 also shows the raw material composition of the adhesive rubber layer. Table 2 shows the raw material composition of the compression rubber layer and the evaluation results.

(Evaluation belt)
<Adhesive rubber material>
As the adhesive rubber material for forming the adhesive rubber layer, EPDM (manufactured by JSR, trade name: JSR EP123) is used as a raw rubber, and carbon black (manufactured by Asahi Carbon Co., Ltd., trade name: : Asahi #60) 50 parts by mass, plasticizer (manufactured by Nippon Sun Oil Co., Ltd., product name: Sunflex 2280) 8 parts by mass, stearic acid (manufactured by Kao Corporation, product name: stearic acid) 1 part by mass, zinc oxide (Sakai Kagaku Kogyo Co., Ltd., trade name: Type 2 zinc oxide) 5 parts by mass, zinc methacrylate (Kawaguchi Chemical Industry Co., Ltd., Actor ZMA) 5 parts by mass, vulcanization accelerator (1) (Ouchi Shinko Kagaku Co., Ltd., Noxcellar MSA-G) 1 part by mass, vulcanization accelerator (2) (manufactured by Sanshin Chemical Industry Co., Ltd., Suncellar EM2) 3 parts by mass, and sulfur (manufactured by Hosoi Chemical Industry Co., Ltd., Oil Sulfur) 1.5 parts by mass. A kneaded unvulcanized rubber composition was prepared. This uncrosslinked rubber composition was processed into a sheet having a thickness of 0.45 mm using a roll. Table 1 also shows the composition of the adhesive rubber material.

<Compressed rubber material>
As a compression rubber material for forming a compression rubber layer, an unvulcanized rubber composition was prepared by blending and kneading the same compounding raw materials as the adhesive rubber material in the compounding amounts shown in Table 2. This uncrosslinked rubber composition was processed into a sheet having a thickness of 0.7 mm using a roll.

<Back rubber material>
A sheet made of an uncrosslinked rubber composition for forming a back rubber layer was prepared in the same manner as in the preparation of the compression rubber material.

<Twisted yarn>
As the twisted yarn for forming the cord, polyester fiber twisted yarn was prepared, immersed in an RFL aqueous solution, and then dried by heating.

<Knit cloth>
The knitted fabric used is a plain knitted (plain knitted) knitted fabric using a urethane elastic thread covered with a 6-nylon thread. The urethane elastic yarn has a fineness of 22 denier (24.4 dtex) and the 6-nylon yarn has a fineness of 78 denier (86.7 dtex) and 52 filaments. The knitting density of the knitted fabric is 66 lines/2.54 cm for the wale and 70 lines/2.54 cm for the course. The thickness of the knitted fabric is 0.52 mm.

A PTFE-containing RFL aqueous solution was prepared for performing RFL bonding treatment on such a knitted fabric. Specifically, resorcin (R) and formalin (F) were mixed, an aqueous sodium hydroxide solution was added, and the mixture was stirred to obtain an RF precondensate (R/F molar ratio=1/1.5). Then, the VP latex (L) is mixed with the RF initial condensate so that the RF / L mass ratio = 1/8, and water is added to adjust the solid content concentration to 20%. 30 parts by mass of PTFE (manufactured by AGC, trade name: Fluon PTFEAD911, PTFE average particle size 0.25 μm, containing 60% by mass of PTFE) is blended with 100 parts by mass per minute, and stirred for 24 hours to form a PTFE-containing RFL aqueous solution. prepared. The RFL coating was formed on the surface of the knitted fabric by immersing the knitted fabric in this PTFE-containing RFL aqueous solution and drying it by heating.

Subsequently, the ends (joint portions) of the RFL-bonded knitted cloth were thermocompressed to each other while applying ultrasonic vibration (frequency of about 80 KHz) to form the knitted cloth into a tubular shape.

(Example 1)
A V-ribbed belt was produced using a belt molding device 30 comprising a rubber sleeve mold 31 for molding the back surface of the belt into a predetermined shape and a cylindrical outer mold 32 for molding the inside of the belt into a predetermined shape. . The cylindrical outer mold 32 has a ridge portion 32a for forming a V-rib on the belt and is provided in the inner side of the cylindrical outer mold 32 in the circumferential direction.

First, as materials constituting the V-ribbed belt, an adhesive rubber material, a compression rubber material, a backing rubber material, a knitted cloth, and a twisted yarn were prepared as described above.
An uncrosslinked rubber material for forming the back rubber layer 17, an uncrosslinked rubber material for forming the adhesive rubber layer, and a twisted thread were wound in this order on the rubber sleeve mold 31 of the belt molding device 30. FIG. Next, an uncrosslinked rubber material for forming an adhesive rubber layer and an uncrosslinked rubber material for forming a compression rubber layer were wound. After that, the tubular knitted cloth subjected to the above bonding treatment was fitted.

Next, a cylindrical outer mold 32 provided with a V-groove was fitted over the belt material to the rubber sleeve mold. After that, the rubber sleeve mold 31 was expanded and pressed against the cylindrical outer mold 32 side, and the rubber sleeve mold 31 was heated with high-temperature steam or the like. At this time, the rubber component flowed, the cross-linking reaction progressed, and in addition, the adhesion reaction of the twisted yarn and the knitted cloth to the rubber also progressed. As a result, a cylindrical belt precursor was obtained.

Finally, this belt precursor was removed from the belt forming device 30, cut in the length direction to a width of 10.68 mm (3PK: number of ribs: 3), and turned over to obtain a V-ribbed belt. . The circumference of the belt is 1210 mm.

(Examples 2 to 5 and Comparative Examples 1 and 2)
A V-ribbed belt having a width of 10.68 mm (3PK: 3 ribs) and a circumferential length of 1210 mm was obtained in the same manner as in Example 1, except that the compression rubber material was changed (see Table 2).

The V-ribbed belts produced in Examples and Comparative Examples were evaluated for physical properties and performance as described below. Table 3 shows the results.

(Evaluation of the physical properties)
For each of the V-ribbed belts produced in Examples and Comparative Examples, thickness T: 0.5 to 1 mm and height H: 1.9 to 2.0 mm using the method already described from the compressed rubber layer of the V-ribbed belt. , and length L: 1.9 to 2.0 mm.
A compression test was performed by compressing this test piece 22 in the thickness direction, and the load (MPa) at 10% compression and the load (MPa) at 5% compression were measured (see FIGS. 2(a) to (d)). .

Here, a universal testing machine (Instro Model 5969) was used as the testing machine, and the measurement was performed at an experimental temperature of 23±2° C. and a compression rate of 1 mm/min. Five specimens were evaluated, and the median value was used as the measured value.
Each of the measured load at 5% compression and load at 10% compression is divided by the cross-sectional area (height H × length L) of the pressing surface 23 at compression, and the obtained value is the stress at 5% compression. (width direction M5) and stress at 10% compression (width direction M10).

(performance evaluation)
<Abrasion resistance evaluation>
FIG. 5 shows the pulley layout of a belt running tester 40 for evaluating wear resistance of V-ribbed belts.
This belt running tester 40 consists of a pair of drive rib pulleys 51 and driven rib pulleys 52 with a pulley diameter of 60 mm arranged on the left and right.

For each of the V-ribbed belts produced in Examples and Comparative Examples, the initial belt mass (belt mass before running test) was first measured. Next, the V-ribbed belt B is wound around the drive rib pulley 41 and the driven rib pulley 42 so that the V-rib sides are in contact with each other, and the drive rib pulley 41 is pulled sideways so that a dead weight (DW) of 1177 N (120 kgf) is applied. At the same time, a rotational load of 3.8 kW (5.2 PS) was applied to the driven rib pulley 42 .
After performing a belt running test in which the driving rib pulley 41 was rotated at a rotation speed of 3500 rpm for 96 hours under a room temperature environment (23±5° C.), the post-run mass of the V-ribbed belt B was measured.

A mass reduction rate was calculated based on the following formula (1) from the measured mass and used as an evaluation index for wear resistance.
Mass reduction rate (mass%) = [(initial mass - mass after running) / initial mass] x 100 (1)
In this evaluation, a mass reduction rate of 2.0% by mass or less was graded "A", a rate of 2.4% by mass or less was graded "B", and a rate of more than 2.4% by mass was graded "C".

As shown in Table 3, according to the V-ribbed belt according to the embodiment of the present invention, good abrasion resistance can be secured.

The friction transmission belt of the present disclosure is useful, for example, in an accessory drive belt transmission for automobiles.

10 Belt body 11 Adhesive rubber layer 11' Adhesive rubber material 11a', 11b' Adhesive rubber material 12 Compressed rubber layer 12' Compressed rubber material 13 V-rib 14 Rib-side reinforcing cloth 14' Knit cloth 16 Cord 16' Twisted thread 17 Back rubber Layer 17' Back rubber material 20, B V-ribbed belt 21 Rib portion 22, 122 Test piece 30 Belt forming device 31 Rubber sleeve mold 32 Cylindrical outer mold 32a Rib portion 40 Belt running tester 41 Drive rib pulley 42 Driven rib pulley

Claims (3)

A friction transmission belt having a compression layer forming a pulley contact portion,
The compression layer includes an inner layer made of a rubber composition and an outer layer made of a fiber member provided on the pulley contact side of the inner layer,
The friction transmission belt, wherein the rubber composition has a stress M10 at 10% compression in the belt width direction of 2.0 MPa or more. 2. The friction transmission belt according to claim 1, wherein the rubber composition has a stress M5 at 5% compression in the belt width direction of 1.2 MPa or more. 3. The friction transmission belt according to claim 1, which is a V-ribbed belt.

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