JP2017110805A - Friction transmission belt and manufacturing method of the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a friction transmission belt capable of enhancing heat radiation from a belt even under a severe condition easily causing thermal deterioration, and suppressing temperature rise of the belt.SOLUTION: A friction transmission belt is manufactured by coating a friction transmission face with a heat radiation layer including heat conductive metallic particles. Heat conductive metallic particles may exist on a surface of the heat radiation layer. Heat conductivity of the heat conductive metallic particles may be 100 W/m L or more. An average particle diameter of the heat conductive metallic particles may be about 1-100 μm. The friction conductive belt 1 includes an extension layer 4 forming a belt back face, a compression layer 2 disposed at one face side of the extension layer, and a core body 3 buried between the extension layer 4 and the compression layer 2 and extended in a belt circumferential direction. A friction conductive face of the compression layer 2 may be coated with a heat radiation layer 5 composed of vulcanizate of a rubber composition including a rubber component and the heat conductive metallic particles.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a friction transmission belt (such as a V-ribbed belt) used for driving an automobile engine accessory and the like, and more particularly to a friction transmission belt in which heat dissipation is promoted from the belt and temperature rise of the belt is suppressed, and It relates to a manufacturing method.

  Frictional power transmission belts such as V-belts, V-ribbed belts, and flat belts are widely known as power transmission belts for transmitting power, and high performance and high performance are demanded particularly for automobiles. As one of such friction transmission belts used for automobiles, there is a V-ribbed belt formed with a plurality of V-shaped ribs extending in the circumferential direction of the belt. Power for driving auxiliary equipment such as an air compressor and an alternator of an automobile Widely used for transmission. Such a V-ribbed belt manufacturing method can be roughly classified into a method of forming the rib portion by grinding and a method of forming the rib portion by a mold.

  The engine room has become extremely hot due to the recent high engine output and compact engine room. In addition, since the winding angle is increased by reducing the diameter of the pulley and the number of bends tends to increase due to the increase in the number of axes, the self-heating due to the bending tends to increase. When the V-ribbed belt generates heat, the hardness of the rubber increases due to thermal deterioration, cracks of the primary failure occur early, transition to the failure of the rib, which is a secondary failure, in a short time, and the running time to the life is shortened. . Further, the thermal deterioration promotes a decrease in the adhesive force between the members constituting the belt (for example, between the core wire and the rubber layer), and the separation between the members occurs early, resulting in a short life. As described above, due to the high output and the compact engine room, the V-ribbed belt is required to have higher heat resistance than the current specification, and it is necessary to provide a belt that matches the required quality.

  Japanese Patent Laid-Open No. 2003-340934 (Patent Document 1) discloses a metal and / or ceramic reinforcement on the inner peripheral surface of a belt as a V-ribbed belt having high wear resistance and cold resistance without performing surface treatment such as grinding and polishing. A V-ribbed belt comprising a compressed rubber layer provided with a layer is disclosed. In the examples of this document, an outer mold in which V-shaped grooves are engraved on a chloroprene rubber sheet laminated with a rubber composition containing nickel powder on the surface or a chloroprene rubber sheet thermally sprayed with nickel powder on the surface is used. Vulcanized and molded.

  International Publication WO2009 / 011414 (Patent Document 2) describes a surface layer constituting a surface abutting against a pulley as an V-ribbed belt having excellent crack resistance and excellent noise prevention effect, and an inner side of the surface layer. A V-ribbed belt is disclosed in which a two-layer structure with an inner layer constituting the surface layer is formed on a rib, and the rubber composition forming the surface layer includes resin particles and / or inorganic particles. This reference exemplifies graphite particles, molybdenum disulfide particles, mica particles, talc particles, antimony trioxide particles, molybdenum diselenide particles, and tungsten disulfide particles as inorganic particles. In the examples of this document, a liquid urethane rubber composition containing polytetrafluoroethylene (PTFE) particles, ultrahigh molecular weight polyethylene particles, silica particles, and carbon black is spray-coated on the surface of a rib formed by searching after vulcanization. And cross-linked.

  However, these documents do not describe thermal deterioration of the V-ribbed belt. Further, in Patent Document 2, since the metal particles are not blended and the surface layer is adhered to the surface of the rib formed by vulcanization and grinding, it is difficult to integrate and the surface layer is likely to fall off.

JP 2003-340934 A (Claims, Examples) International Publication WO2009 / 011414 Pamphlet (Claims, Paragraph [0038], Examples)

  Accordingly, an object of the present invention is to provide a friction transmission belt that can promote heat dissipation from the belt even under harsh conditions that are likely to be thermally deteriorated, and can suppress an increase in the temperature of the belt, and a method for manufacturing the same.

  Another object of the present invention is to provide a friction transmission belt that can suppress the generation of cracks, breakage of ribs, and peeling between members even when running for a long period of time, and a method for manufacturing the same.

  As a result of intensive investigations to achieve the above-mentioned problems, the present inventors have found that harsh conditions are likely to cause thermal degradation by covering the friction transmission surface of the friction transmission belt with a heat dissipation layer containing thermally conductive metal particles. However, the present inventors have found that heat dissipation from the belt can be promoted and the temperature rise of the belt can be suppressed, and the present invention has been completed.

  That is, in the friction transmission belt of the present invention, the friction transmission surface is covered with a heat dissipation layer containing thermally conductive metal particles. Thermally conductive metal particles may be present on the surface of the heat dissipation layer. The thermal conductivity at 100 ° C. of the thermally conductive metal particles may be 100 W / m · K or more. The heat conductive metal particles may have an average particle size of about 1 to 100 μm. The heat conductive metal particles may have a substantially spherical shape. The area ratio of the thermally conductive metal particles to the entire friction transmission surface may be about 5 to 95%. The average thickness of the heat dissipation layer may be about 10 to 300 μm. The heat dissipation layer may be formed of a vulcanized product of a rubber composition containing a rubber component and thermally conductive metal particles. About 10-2000 mass parts may be sufficient as the ratio of the said heat conductive metal particle with respect to 100 mass parts of rubber components. The friction transmission belt of the present invention includes a compression layer formed of a vulcanized rubber composition containing a rubber component, and a friction transmission belt having a friction transmission surface formed on the compression layer. The rubber component and the rubber component of the heat dissipation layer may be the same rubber component. The friction transmission belt of the present invention may be a V-ribbed belt having a plurality of V-shaped rib portions extending in the belt circumferential direction.

  The present invention also includes a method for producing the friction transmission belt including a coating step of covering the friction transmission surface with a heat radiation layer precursor containing thermally conductive metal particles.

  In particular, the friction transmission belt in which the heat dissipation layer is formed of a vulcanized product of a rubber composition containing a rubber component and thermally conductive metal particles is a frictional transmission surface made of a rubber composition containing a rubber component and thermally conductive metal particles. It may be obtained by a production method including a coating step for coating the rubber composition and a vulcanization step for vulcanizing the rubber composition coated on the friction transmission surface. In the coating step, a liquid rubber composition containing a rubber component and thermally conductive metal particles may be attached to the friction transmission surface. In the coating step, a sheet formed of a rubber composition containing a rubber component and heat conductive metal particles may be laminated on the friction transmission surface.

  In the present invention, since the friction transmission surface of the friction transmission belt is covered with the heat dissipation layer containing the heat conductive metal particles, the heat dissipation from the belt can be promoted even under severe conditions that are likely to be thermally deteriorated. Temperature rise can be suppressed. Therefore, even if it runs for a long period of time, generation | occurrence | production of a crack, destruction of a rib, and peeling between members can be suppressed, and lifetime can be extended.

FIG. 1 is a schematic sectional view showing an example of a friction transmission belt (V-ribbed belt) according to the present invention. FIG. 2 is a schematic diagram for explaining a method of measuring the heat dissipation characteristics of the belts obtained in the examples and comparative examples.

  Hereinafter, the present invention will be described in detail with reference to the accompanying drawings as necessary.

  The friction transmission belt of the present invention is not particularly limited as long as it has a friction transmission surface that can come into contact with a pulley, and may be a V belt, a V-ribbed belt, a flat belt, or the like. Further, the friction transmission belt may be a belt in which a friction transmission portion (rib or the like) is formed, and a typical transmission belt is formed with a plurality of V-shaped rib portions extending in the belt circumferential length direction. It is a highly efficient V-ribbed belt.

  As shown in FIG. 1, such a friction transmission belt (V-ribbed belt) 1 forms a belt back surface (the outer peripheral surface of the belt) and is composed of a cover canvas (woven fabric, knitted fabric, non-woven fabric, etc.). A compression layer (compression rubber layer) 2 having a friction transmission surface (surface of the friction transmission portion) formed on one side (one surface side) of the stretch layer 4, and this compression layer (compression rubber layer) 2 The inner surface of the belt is coated (laminated) on the friction transmission surface of the belt, and between the heat-dissipating layer 5 that can come into contact with the pulley and the stretch layer 4 and the compression layer 2 in the belt longitudinal direction (circumferential direction) And a core body 3 buried along. In this example, the core body 3 is a core wire (twisted cord) arranged at a predetermined interval in the belt width direction, and is in contact with the stretch layer 4 and the compression layer 2 and is interposed between both layers.

  A plurality of V-shaped grooves extending in the longitudinal direction of the belt are formed in the compression layer 2, and a plurality of ribs having a V-shaped section (inverted trapezoid) are formed between the grooves. The surface (surface) forms a friction transmission surface. The friction transmission surface can come into contact with the pulley via the heat dissipation layer 5, and thermally conductive metal particles are held on the surface and inside of the heat dissipation layer 5.

  In addition, this invention is applied suitably for the power transmission belt in which the friction transmission surface (or friction power transmission part) with the pulley was formed in the compression layer 2. FIG. The friction transmission belt of the present invention is not limited to the above structure. For example, the stretch layer 4 may be formed of a rubber composition, and the core 3 and the stretch layer 4 are interposed between the compression layer 2 and the stretch layer 4. Or in order to improve adhesiveness with the compression layer 2, you may interpose an adhesive layer. The core 3 may be embedded between the stretch layer 4 and the compression layer 2. For example, the core body 3 may be embedded in the compression layer 2 or may be embedded in the compression layer 2 while being in contact with the stretch layer 4. Furthermore, the core body 3 may be embedded in the adhesive layer, or the core body 3 may be embedded between the compression layer 2 and the adhesive layer or between the adhesive layer and the stretch layer 4.

  Below, the detail of each member which comprises a belt, and the manufacturing method of a belt is demonstrated.

[Heat dissipation layer]
The heat dissipation layer includes thermally conductive metal particles, and the presence of the thermally conductive metal particles on the friction transmission surface can exhibit a heat dissipation effect and suppress an increase in the temperature of the friction belt.

  Examples of the heat conductive metal constituting the heat conductive metal particles include alkali metals (for example, sodium, potassium, etc.), alkaline earth metals (for example, beryllium, magnesium, etc.), transition metals (for example, titanium, etc.) Table 4A metal; Periodic table Group 5A metal such as tantalum; Periodic table Group 6A metal such as chromium, molybdenum and tungsten; Group 7A metal such as rhenium; Nickel, iron, cobalt, rhodium, palladium, Periodic Table Group 8 metals such as iridium and platinum; Periodic Table Group 1B metals such as copper, silver and gold), Periodic Table Group 2B metals (eg, zinc, cadmium, etc.), Periodic Table Group 3B metals ( For example, aluminum, gallium, indium, etc.), periodic table group 4B metal (eg, tin, lead, etc.), periodic table group 5B metal (eg, anne) Mont, etc.), and the like. These conductive metals can be used alone or in combination of two or more. Further, the conductive metal may be an alloy such as brass.

  Among these, metals having high thermal conductivity, for example, periodic table group 6A metals such as molybdenum and tungsten, periodic table group 8 metals such as rhodium and iridium, and periodic table group 1B metals such as copper, silver and gold A periodic table group 2B metal such as zinc and a periodic table group 3B metal such as aluminum and indium are preferred, and molybdenum, copper, silver, gold and aluminum are particularly preferred.

  The heat conductivity at 100 ° C. of the heat conductive metal particles (the heat conductive metal constituting the particles) may be 10 W / m · K or more (particularly 20 W / m · K or more), but is excellent in heat dissipation. From the point of view, it may be 100 W / m · K or more (for example, about 100 to 500 W / m · K), preferably 150 W / m · K or more, more preferably 200 W / m · K or more (particularly 300 to 450 W / m · K). Furthermore, the heat conductive metal particle is a metal having a heat conductivity of 300 W / m · K or more (for example, 300 to 500 W / m · K) such as silver and copper because the life of the belt due to thermal deterioration can be greatly improved. The formed particles are preferable, and particles formed of a metal having a thermal conductivity of 350 W / m · K or more (for example, 400 to 450 W / m · K) are particularly preferable.

  Examples of the shape of the heat conductive metal particles include, for example, a sphere (true sphere or substantially sphere), an ellipsoid (elliptical sphere), a polygon (a polygonal shape such as a polygonal pyramid, a tetragonal shape, and a rectangular parallelepiped) Shape (flat shape, scale shape, flake shape, etc.), rod shape or rod shape, fiber shape, tree needle shape, indefinite shape and the like. The shape of the heat conductive metal particles is usually spherical, ellipsoidal, polygonal, indefinite or the like. Of these shapes, a substantially spherical shape is preferable from the viewpoint that the heat dissipation layer can be easily uniformly dispersed and highly filled, and heat dissipation can be improved.

  The central particle diameter or average particle diameter (D50) of the heat conductive metal particles is, for example, about 1 to 100 μm (for example, 2 to 50 μm), preferably 3 to 30 μm, more preferably about 5 to 25 μm (particularly 10 to 20 μm). . The maximum particle size may be, for example, 100 μm or less, preferably 50 μm or less, and more preferably 30 μm or less. If the particle size is too small, uniform dispersion in the heat-dissipating layer becomes difficult and heat dissipation may be reduced. If it is too large, adhesion to the friction transmission surface may be reduced.

  In the present specification and claims, the center particle size and the maximum particle size mean an average particle size measured using a laser diffraction / scattering particle size distribution measuring apparatus.

  The heat dissipation layer only needs to contain the heat conductive metal particles, and may be formed of only the heat conductive metal particles. However, since the heat conductive metal particles can be firmly fixed to the friction transmission surface, In addition to the conductive metal particles, a binder component is preferably included.

  When the heat dissipation layer contains a binder component, it is sufficient that the heat conductive metal particles are contained in the heat dissipation layer, but from the point that heat dissipation can be improved, the heat conductive metal particles are present on the surface of the heat dissipation layer. preferable. The area ratio of the heat conductive metal particles to the entire friction transmission surface may be 5% or more with respect to the entire friction transmission surface, for example, 5 to 95%, preferably 20 to 90%, more preferably 40. It is about -85% (especially 60-80%). If the area ratio of the heat conductive metal particles is too small, the heat dissipation may be reduced. In the present specification and claims, the area ratio of the thermally conductive metal particles is determined by a method in which an image of a friction transmission surface is image-processed by a computer using a camera (smart camera) having an image processing function. Specifically, it can be measured by the method described in Examples described later.

  The binder component may be a polymer component such as an adhesive resin, but is preferably a rubber component from the viewpoint of excellent adhesion to the friction transmission surface. In particular, the heat dissipation layer containing a rubber component is preferably formed of a vulcanized product of a rubber composition containing a rubber component and thermally conductive metal particles, and a rubber component that forms a friction transmission surface (usually a compression layer). The rubber component is particularly preferably formed of a vulcanized product of a rubber composition containing the same or the same type (particularly the same) rubber component and thermally conductive metal particles.

  The heat radiation layer formed of the rubber composition vulcanizate is fixed in a state where the heat conductive metal particles are integrated with the rubber component, and the friction transmission surface (rib surface) of the belt at the initial stage of running of the belt. When the rubber thin film is scattered, the heat conductive metal particles are exposed. In this state, when the belt continues to run while contacting the pulley, the heat conductive metal particles are caused to flow into the water compared to the case where the heat conductive metal particles are adhered to the friction transmission surface after vulcanization of the belt. The risk that the effect of the thermally conductive metal particles disappears due to detachment from the friction transmission surface or missing due to contact friction with the pulley at the initial stage of travel is greatly reduced. For this reason, the thermally conductive metal particles fixed in an integrated state with the friction transmission surface are held without disappearing in the running process, and the temperature rise of the belt can be suppressed by the heat dissipation effect. Further, the effect can be maintained by holding the heat conductive metal particles on the belt for a long time. The effects obtained by suppressing the temperature rise of the belt for a long time are as follows: (1) Cracking caused by rubber hardening is suppressed by suppressing the hardness increase due to thermal deterioration of rubber (rib rubber, etc.) constituting the compression layer. (2) Separation between members by suppressing a decrease in adhesive force due to thermal deterioration between members (for example, between an elastic rubber and a core wire, between a compression layer and a core wire, etc.) It is possible to delay the damage phenomenon caused by the damage. As a result, in the present invention, the time until the occurrence of the breakage phenomenon becomes longer, and the life of the belt can be extended.

  Examples of the rubber component include known rubber components and / or elastomers such as diene rubber (natural rubber, isoprene rubber, butadiene rubber, chloroprene rubber, styrene butadiene rubber (SBR), acrylonitrile butadiene rubber (nitrile rubber), hydrogenated nitrile. Rubber (including mixed polymers of hydrogenated nitrile rubber and unsaturated carboxylic acid metal salt), ethylene-α-olefin elastomer, chlorosulfonated polyethylene rubber, alkylated chlorosulfonated polyethylene rubber, epichlorohydrin rubber, acrylic rubber Examples thereof include silicone rubber, urethane rubber, and fluorine rubber. These components can be used alone or in combination. Among these rubber components, ethylene-α-olefin elastomers (ethylene-propylene rubber (EPR), ethylene-propylene rubber (EPR), free from harmful halogens, have ozone resistance, heat resistance, cold resistance, and are economical. Ethylene-α-olefin rubbers such as ethylene-propylene-diene rubbers (EPDM, etc.) are preferred.

  The ratio of the heat conductive metal particles is, for example, about 10 to 2000 parts by mass, preferably 20 to 1000 parts by mass, and more preferably about 30 to 500 parts by mass (particularly 40 to 100 parts by mass) with respect to 100 parts by mass of the rubber component. It is. If the proportion of the thermally conductive metal particles is too small, the heat dissipation may be reduced, and if too large, the adhesion to the friction transmission surface may be reduced.

  In addition to the thermally conductive metal particles and the rubber component, the rubber composition may include, for example, a vulcanizing agent or a crosslinking agent selected according to the type of the rubber component [for example, a sulfur-based vulcanizing agent (sulfur ), Oximes (such as quinone dioxime), guanidines (such as diphenyl guanidine), organic peroxides (such as diacyl peroxide, peroxyester, dialkyl peroxide), metal oxides (magnesium oxide, oxidation) Zinc) and the like], vulcanization aids, vulcanization accelerators, vulcanization retarders, and the like. The rubber composition may further contain an additive contained in the compression layer described later. In particular, the rubber composition is preferably the same rubber composition as the compression layer from the viewpoint of adhesion to the compression layer.

  The average thickness of the heat dissipation layer is, for example, about 10 to 300 μm, preferably 15 to 200 μm, more preferably about 20 to 150 μm (particularly 30 to 100 μm). If the thickness of the heat dissipation layer is too thin, heat dissipation may be reduced, and if it is too thick, the mechanical properties of the belt may be deteriorated. In addition, in this specification and a claim, the average thickness of a thermal radiation layer can be measured based on a scanning electron micrograph (SEM), and calculates | requires it as an average value of arbitrary five or more places. The details can be measured by the method described in Examples described later.

[Compression layer]
The compression layer can usually be formed of rubber (or a rubber composition). As rubber (rubber which comprises a rubber composition), the rubber component illustrated by the term of the said thermal radiation layer can be illustrated.

  The ratio of the rubber to the entire compression layer (or the total amount of the rubber composition) is, for example, 20% by mass or more (for example, 25 to 80% by mass), preferably 30% by mass or more (for example, 35 to 75% by mass), and more preferably 40%. It may be not less than mass% (especially 45 to 70 mass%).

  The compression layer (or rubber or rubber composition forming the compression rubber layer) may contain various additives as necessary. Examples of the additive (compounding agent) include known additives, for example, the vulcanizing agent or the crosslinking agent exemplified in the section of the heat dissipation layer, the vulcanization aid, the vulcanization accelerator, the vulcanization retarder, Carbon black, silicon oxide such as hydrous silica), metal oxides (eg, zinc oxide, magnesium oxide, calcium oxide, barium oxide, iron oxide, copper oxide, titanium oxide, aluminum oxide), fillers (clay, carbonic acid, etc.) Calcium, talc, mica, etc.), plasticizers, softeners (paraffin oil, oils such as naphthenic oil), processing agents or processing aids (stearic acid, metal stearate, wax, paraffin, etc.), anti-aging Agent (aromatic amine-based anti-aging agent, benzimidazole-based anti-aging agent, etc.), adhesion improver [resorcin-formaldehyde co-condensate, hexamethoxy Melamine resins such as tilmelamine, co-condensates thereof (resorcin-melamine-formaldehyde co-condensate, etc.), colorants, tackifiers, coupling agents (silane coupling agents, etc.), stabilizers (antioxidants, UV absorbers, heat stabilizers, etc.), lubricants, flame retardants, antistatic agents and the like. These additives can be used alone or in combination, and these additives can be selected according to the type, application, performance and the like of the rubber.

  The proportion of the additive can also be appropriately selected according to the type of rubber. For example, the ratio of the reinforcing agent (carbon black or the like) is 10 parts by mass or more (for example, 20 to 150 parts by mass), preferably 20 parts by mass or more (for example, 25 to 120 parts by mass), more preferably 100 parts by mass of rubber. May be 30 parts by mass or more (for example, 35 to 100 parts by mass), particularly 40 parts by mass or more (for example, 50 to 80 parts by mass).

  The compression layer (or rubber composition) may contain short fibers. Examples of the short fibers include cellulose fibers such as cotton and rayon, polyester fibers (PET fibers, etc.), polyamide fibers (aliphatic polyamide fibers such as polyamide 6, aramid fibers, etc.), and the like. The short fiber may be a water absorbent fiber. The short fibers may be used alone or in combination of two or more.

  The average fiber length of the short fibers may be, for example, about 0.1 to 30 mm, preferably 0.2 to 20 mm, more preferably about 0.3 to 15 mm (particularly 0.5 to 5 mm).

  These short fibers may be surface-treated with a surfactant, a silane coupling agent, an epoxy compound, an isocyanate compound, or the like, if necessary.

  The proportion of short fibers is, for example, about 0.5 to 50 parts by mass (for example, 1 to 40 parts by mass), preferably about 3 to 30 parts by mass (particularly 5 to 25 parts by mass) with respect to 100 parts by mass of rubber. Also good.

  The thickness of the compression layer (compression rubber layer or the like) can be appropriately selected according to the type of belt, and may be, for example, 1 to 30 mm, preferably 1.5 to 25 mm, and more preferably about 2 to 20 mm.

(Core)
Although it does not specifically limit as a core, Usually, the core wire (twisted cord) arranged at predetermined intervals in the belt width direction can be used. The core wire is not particularly limited, and may include, for example, synthetic fibers such as polyester fibers (polyalkylene arylate fibers) and polyamide fibers (aramide fibers), inorganic fibers such as carbon fibers, and the like.

  As the core wire, a twisted cord using multifilament yarn (for example, various twists, single twists, rung twists, etc.) can be used. The average wire diameter (fiber diameter of the twisted cord) of the core wire may be, for example, about 0.5 to 3 mm, preferably about 0.6 to 2 mm, and more preferably about 0.7 to 1.5 mm. The core wire may be embedded in the longitudinal direction of the belt, or may be embedded in parallel at a predetermined pitch parallel to the longitudinal direction of the belt.

  In order to improve adhesiveness with rubber, the core wire may be subjected to various adhesion treatments using an epoxy compound, an isocyanate compound, or the like, similarly to the short fiber.

(Stretch layer)
The stretch layer may be formed of the same rubber composition as the compression layer, or may be formed of a fabric (reinforcing fabric) such as a canvas. Examples of the cloth (reinforcing cloth) include cloth materials such as woven cloth, wide-angle sail cloth, knitted cloth, and non-woven cloth. Among these, a woven fabric woven in the form of plain weave, twill weave, satin weave, or a wide angle canvas or knitted fabric in which the crossing angle between the warp and the weft is about 90 to 120 ° is preferable. As the fibers constituting the reinforcing cloth, the fibers exemplified in the section of the fiber member (water-absorbing fibers, non-water-absorbing fibers, etc.) can be used.

  The reinforcing cloth may be subjected to an adhesion treatment [for example, an adhesion treatment such as a dipping treatment in a resorcin-formalin-latex liquid (RFL liquid)]. Further, after the adhesion treatment, the rubber composition may be formed by friction or rubbing (coating) the rubber composition.

  The stretch layer may be formed of rubber (rubber composition). The rubber composition may further contain short fibers similar to those in the compression layer in order to suppress abnormal noise generated due to adhesion of the back rubber during back drive. The short fibers may be randomly oriented in the rubber composition. Further, the short fiber may be a short fiber partially bent.

  Furthermore, an uneven pattern may be provided on the surface of the stretched layer (the back surface of the belt) in order to suppress abnormal noise during back surface driving. Examples of the uneven pattern include a knitted fabric pattern, a woven fabric pattern, a suede woven fabric pattern, and an embossed pattern. Of these patterns, a woven fabric pattern and an embossed pattern are preferable. Furthermore, you may coat | cover at least one part of the back surface of an extending | stretching layer with a fiber resin mixed layer.

  The thickness of the stretched layer can be appropriately selected according to the type of the belt, but may be, for example, about 0.5 to 10 mm, preferably about 0.7 to 8 mm, and more preferably about 1 to 5 mm.

(Adhesive layer)
As described above, the adhesive layer is not always necessary. The adhesive layer (adhesive rubber layer) can be composed of, for example, a rubber composition (rubber composition containing a rubber component such as ethylene-α-olefin elastomer) similar to the compression layer (compressed rubber layer). The rubber composition of the adhesive layer may further contain an adhesion improver (resorcin-formaldehyde cocondensate, amino resin, etc.).

  The thickness of the adhesive layer can be appropriately selected according to the type of belt, but may be, for example, about 0.2 to 5 mm, preferably about 0.3 to 3 mm, and more preferably about 0.5 to 2 mm.

  In the rubber composition of the stretch layer and the adhesive layer, the same rubber or the same type of rubber as the rubber component of the rubber composition of the compressed rubber layer is often used as the rubber component. Further, in these rubber compositions, the proportion of additives such as a vulcanizing agent or a crosslinking agent, a co-crosslinking agent or a crosslinking aid, and a vulcanization accelerator is from the same range as the rubber composition of the compression layer, respectively. You can choose.

[Method of manufacturing friction transmission belt]
In the present invention, the friction transmission surface (compressed rubber layer) is obtained through a coating step of covering the friction transmission surface with a heat dissipation layer precursor containing heat conductive metal particles. When the rubber composition is formed of a vulcanized product of a rubber composition containing conductive metal particles, heat is radiated to the friction transmission surface of the compression layer by further vulcanizing the rubber composition covering the friction transmission surface. A friction transmission belt having a layer formed can be manufactured.

(Coating process)
In the coating step, as a method of coating the friction transmission surface with the rubber composition, a method of adhering a liquid rubber composition containing a rubber component and thermally conductive metal particles to the friction transmission surface (adhesion treatment), a rubber component, and Examples thereof include a method of laminating a sheet formed of a rubber composition containing thermally conductive metal particles on a friction transmission surface (lamination treatment).

  In the adhesion treatment, a rubber composition (unvulcanized rubber composition) for forming a heat radiation layer is usually diluted with a solvent to prepare a liquid rubber composition (rubber paste).

  Examples of the solvent include hydrocarbons (for example, aromatic hydrocarbons such as toluene and xylene), halogenated hydrocarbons (for example, haloalkanes such as methylene chloride and chloroform), alcohols, etc., depending on the type of rubber. (Alkanols such as ethanol, propanol, and isopropanol), ethers (eg, cyclic ethers such as dioxane and tetrahydrofuran), esters (eg, ethyl acetate, etc.), ketones (eg, acetone, methyl ethyl ketone, etc.) Examples thereof include cyclic ketones such as ketone and cyclohexanone), cellosolves, carbitols and the like. The solvent may be used alone or as a mixed solvent.

  The ratio of the solvent may be, for example, about 0.5 to 50 parts by mass, preferably about 1 to 20 parts by mass with respect to 1 part by mass of the rubber.

  In the adhesion treatment, the liquid rubber composition may be adhered by the method of vulcanizing and molding the surface of the rubber sheet for forming the compression layer (surface for forming the friction transmission surface) and / or the rubber sheet. Examples thereof include a method of applying a liquid rubber composition to the inner peripheral surface of a mold (outer mold) and a spraying method.

  In the lamination process, a rubber layer for forming a heat radiation layer (unvulcanized rubber composition) is usually molded into a sheet shape to prepare a rubber sheet for the heat radiation layer, and a compression layer for forming a compression layer The rubber sheet is laminated on the surface (surface for forming a friction transmission surface). Furthermore, in order to improve the adhesion between the two layers, the liquid rubber composition (rubber paste) containing no thermally conductive metal particles is interposed between the heat radiation layer rubber sheet and the compression layer rubber sheet. Alternatively, the contact surfaces of both layers may be swollen with the solvent.

  Among these methods, the method of adhering the liquid rubber composition to the friction transmission surface is particularly preferable from the viewpoint that the heat conductive metal particles are easily dispersed uniformly and the heat dissipation effect is high.

(Vulcanization process)
In the vulcanization step, in the coating step, the rubber sheet for forming the compression layer is covered with the rubber composition for forming the heat dissipation layer, and the rubber composition of both layers is vulcanized to form both layers. Can be carried out by a known or conventional method other than through a coating step. For example, in the case of a V-ribbed belt, a compressed layer sheet (a sheet processed according to the type of the coating step) And the core and the stretch layer sheet are laminated, the obtained laminate is molded into a cylindrical shape with a molding die, vulcanized to form a sleeve, and the vulcanized sleeve is cut to a predetermined width. Thus, a V-ribbed belt in which the friction transmission surface (compressed rubber layer) is covered with a heat dissipation layer can be produced.

  More specifically, the V-ribbed belt can be manufactured, for example, by the following method.

(First manufacturing method)
First, using a cylindrical inner mold having a flexible jacket on the outer peripheral surface, an unvulcanized stretch layer sheet is wound around the flexible jacket on the outer peripheral surface, and a core is formed on the sheet (Twist cord) is spun into a spiral shape, and an unvulcanized compression layer sheet is wound around to produce a laminate. Further, as described above, the compression layer sheet is further subjected to the treatment for forming the heat dissipation layer through the above-described covering step. Next, as an outer mold that can be attached to the inner mold, a cylindrical outer mold in which a plurality of rib molds are engraved on the inner peripheral surface is used, and an inner mold in which the laminate is wound is provided in the outer mold. Install concentrically. Thereafter, the flexible jacket is expanded toward the inner peripheral surface (rib type) of the outer mold, and the laminate (compressed layer) is pressed into the rib mold and vulcanized. In this case, as described above, the liquid rubber composition for forming the heat radiation layer may be adhered to the inner peripheral surface of the outer mold and vulcanized. Then, after removing the inner mold from the outer mold and removing the vulcanized rubber sleeve having a plurality of ribs from the outer mold, the vulcanized rubber sleeve is cut to a predetermined width in the longitudinal direction of the belt using a cutter. Finish the ribbed belt. In this first manufacturing method, a laminated body including an extension layer, a core body, a compression layer, and a heat dissipation layer can be expanded at once to be finished into a sleeve (or V-ribbed belt) having a plurality of ribs.

(Second manufacturing method)
In relation to the first manufacturing method, for example, a method disclosed in JP-A-2004-82702 [only a heat radiation layer and a compression layer are expanded to form a preform (semi-vulcanized state), and then an extension layer] A method in which the core body is expanded and pressure-bonded to the preform, and vulcanized and integrated into a V-ribbed belt] may be employed.

  Hereinafter, the present invention will be described in more detail based on examples, but the present invention is not limited to these examples. In addition, the preparation method of a rubber composition, the measuring method or evaluation method of each physical property etc. are shown below.

[Rubber composition]
The rubber composition A shown in Table 1 was kneaded with a Banbury mixer, and the kneaded rubber was passed through a calender roll to prepare an unvulcanized rolled rubber sheet (compression layer sheet) having a predetermined thickness. Further, using the rubber composition B shown in Table 1, a stretch layer sheet was produced in the same manner as described above. In addition, the component of Table 1 is as follows.

EPDM: “Nodel IP4640” manufactured by Dow Chemical
Zinc oxide: manufactured by Shodo Chemical Industry Co., Ltd., "Zinc oxide 3 types"
Carbon black: “Seast V” manufactured by Tokai Carbon Co., Ltd., average particle size 55 nm
Softener: Paraffinic oil, manufactured by Idemitsu Kosan Co., Ltd., “NS-90”
Anti-aging agent: “NOCRACK MB” manufactured by Ouchi Shinsei Chemical Industry Co., Ltd.
Organic peroxide: NOF Corporation, “Park Mill D-40”
Co-crosslinking agent: “Barunok PM” manufactured by Ouchi Shinsei Chemical Industry Co., Ltd.
Cotton short fiber: Denim, average fiber diameter 13μm, average fiber length 3mm

[Liquid rubber composition A for heat radiation layer]
8 parts by mass of rubber composition A shown in Table 1, 4 parts by mass of aluminum powder (“ALPASTEP 0100” manufactured by Toyo Aluminum Co., Ltd., particle size 2 to 30 μm, spherical) and 88 parts by mass of toluene are mixed to obtain a liquid for the heat radiation layer. A rubber composition (rubber paste) A was prepared.

[Liquid rubber composition B for heat dissipation layer]
Liquid rubber for heat dissipation layer in the same manner as liquid rubber composition A for heat dissipation layer, except that zinc powder (made by Hakusuitec Co., Ltd., brand “F powder”, particle size 3 to 5 μm, spherical) is used instead of aluminum powder. Composition B was prepared.

[Liquid rubber composition C for heat dissipation layer]
Except for using aluminum powder instead of aluminum powder (“SPN10JS” manufactured by Mitsui Kinzoku Co., Ltd., specific surface area 0.4 m ² / g, spherical), liquid rubber for heat dissipation layer is the same as liquid rubber composition A for heat dissipation layer. Composition C was prepared.

[Liquid rubber composition D for heat dissipation layer]
Except for using aluminum powder instead of aluminum powder (“TS-150” manufactured by Toho Tech Co., Ltd., particle size of about 150 μm), the liquid rubber composition D for the heat dissipation layer is the same as the liquid rubber composition A for the heat dissipation layer. Was prepared.

[Sheet-like rubber composition for heat dissipation layer]
8 parts by mass of rubber composition A shown in Table 1 and 4 parts by mass of aluminum powder (“ALPASTEP0100” manufactured by Toyo Aluminum Co., Ltd., particle size 2 to 30 μm, spherical) are kneaded with a Banbury mixer, and the kneaded rubber is calendered. Then, a sheet-like rubber composition for a heat dissipation layer having a thickness of 0.25 mm was prepared.

[Area ratio of thermally conductive metal particles]
The area ratio of the thermally conductive metal particles was measured using a microscope (manufactured by Keyence Co., Ltd., model number: VHX-5000), and the friction transmission surface was photographed, and measurement software (Olympus Co., Ltd., “Stream”) was used. When the heat conductive metal particles are aluminum, silver and other (fiber and rubber) are recognized as black and measured.

[Average thickness of heat dissipation layer]
The average thickness of the heat-dissipating layer was measured and averaged by measuring thicknesses at five or more locations using a scanning electron micrograph (SEM).

[Heat dissipation characteristics]
As shown in FIG. 2, the belt temperature (the surface on the contact side with the pulley of the V-ribbed belt) was measured after 5 minutes of traveling under a set tension of 2 levels (1650N, 1350N).

Example 1
Using a cylindrical inner mold with a flexible jacket on the outer peripheral surface, an unvulcanized stretch layer sheet is wrapped around the flexible jacket on the outer peripheral surface, and a core wire (twisted cord) serving as a core on this sheet ) Was spirally spun and an unvulcanized compression layer sheet was wound around to produce a laminate. Further, the heat radiation layer liquid rubber composition A was applied to the surface of the compression layer sheet using a spray gun so as to have a dry thickness of 50 μm. In addition, the polyester cord of 1100 dtex / 2x3 structure was used for the core wire. In order to improve the adhesion to rubber, the core wire is pre-immersed in resorcin-formalin-latex solution (RFL solution) and then coated with a treatment solution in which a rubber composition containing EPDM is dissolved in an organic solvent (toluene). Processed.

  The inner mold around which the cylindrical laminate is wound is placed concentrically in a cylindrical outer mold in which a plurality of rib molds are engraved on the inner peripheral surface, and the flexible jacket is expanded to obtain the laminate. It was pressed into a rib mold and vulcanized. Then, the inner mold is extracted from the outer mold, the vulcanized rubber sleeve having a plurality of ribs is removed from the outer mold, and the vulcanized rubber sleeve is cut to a predetermined width in the longitudinal direction of the belt by using a cutter. A ribbed belt (6 ribs, circumferential length 1200 mm) was produced. The area ratio of the heat conductive metal particles of the obtained V-ribbed belt was 90%, and the average thickness of the heat dissipation layer was 30 μm.

Example 2
A V-ribbed belt was produced in the same manner as in Example 1 except that the heat radiation layer liquid rubber composition B was used instead of the heat radiation layer liquid rubber composition A.

Example 3
A V-ribbed belt was produced in the same manner as in Example 1 except that the heat radiation layer liquid rubber composition C was used instead of the heat radiation layer liquid rubber composition A.

Example 4
A V-ribbed belt was produced in the same manner as in Example 1 except that the heat radiation layer liquid rubber composition D was used instead of the heat radiation layer liquid rubber composition A.

Comparative Example 1
Instead of applying the liquid rubber composition A for the heat dissipation layer, an adhesive (“Quick Dry Water Adhesive FT1000NF” manufactured by 3M Japan Co., Ltd.) is applied and pile (short fiber, “Nylon” manufactured by Nissen Co., Ltd.) is applied. A V-ribbed belt was produced in the same manner as in Example 1 except that a pile (fiber length 0.4 mm) was planted.

  Table 2 shows the results of evaluating the heat radiation characteristics (belt temperature) of the V-ribbed belts obtained in Examples 1 to 4 and Comparative Example 1.

  As is apparent from the results in Table 2, the temperature of the belt of the example is lower than the temperature of the belt of the comparative example. Was 4.3 ° C lower, and the axial load was 1350N, 3.3 ° C lower. Especially, the temperature of the belt of Example 3 containing silver powder was particularly low.

Example 5
A V-ribbed belt was produced in the same manner as in Example 1 except that the heat radiation layer liquid rubber composition A was applied instead of the heat radiation layer sheet rubber composition.

  As is apparent from the results in Table 3, even when the sheet-like rubber composition was used, the temperature of the belt was low as in the belt obtained using the liquid rubber composition.

  The friction transmission belt of the present invention can be used as a friction transmission belt such as a flat belt, a V belt, and a V-ribbed belt. In addition, the friction transmission belt of the present invention can suppress an increase in belt temperature even if it travels for a long time, and thus can be suitably used for high load transmission devices used outdoors such as automobiles, motorcycles, agricultural machines, and thermal degradation. Even under harsh conditions that can be easily performed, the life can be extended, and therefore, it can be particularly suitably used for a V-ribbed belt used for driving an automobile engine accessory whose temperature in an engine room is increasing.

1 Friction transmission belt (V-ribbed belt)
2 ... Compressed layer 3 ... Core 4 ... Stretch layer 5 ... Heat dissipation layer

Claims (15)

  A friction transmission belt having a friction transmission surface coated with a heat dissipation layer containing thermally conductive metal particles.   The friction transmission belt according to claim 1, wherein thermally conductive metal particles are present on the surface of the heat dissipation layer.   The frictional power transmission belt according to claim 1 or 2, wherein the thermal conductivity of the thermally conductive metal particles at 100 ° C is 100 W / m · K or more.   The friction transmission belt according to claim 1, wherein the heat conductive metal particles have an average particle diameter of 1 to 100 μm.   The frictional power transmission belt according to any one of claims 1 to 4, wherein the thermally conductive metal particles have a substantially spherical shape.   The friction transmission belt according to any one of claims 1 to 5, wherein an area ratio of the heat conductive metal particles to the entire friction transmission surface is 5 to 95%.   The frictional power transmission belt according to any one of claims 1 to 6, wherein the heat dissipation layer has an average thickness of 10 to 300 µm.   The frictional power transmission belt according to any one of claims 1 to 7, wherein the heat radiation layer is formed of a vulcanized product of a rubber composition containing a rubber component and thermally conductive metal particles.   The friction transmission belt according to claim 8, wherein the proportion of the heat conductive metal particles is 10 to 2000 parts by mass with respect to 100 parts by mass of the rubber component.   A friction transmission belt comprising a compression layer formed of a vulcanizate of a rubber composition containing a rubber component, and a friction transmission surface formed on the compression layer, the rubber component of the compression layer and the rubber of the heat dissipation layer The friction transmission belt according to claim 8 or 9, wherein the components are the same rubber component.   The friction transmission belt according to any one of claims 1 to 10, which is a V-ribbed belt having a plurality of V-shaped rib portions extending in a belt circumferential direction.   The manufacturing method of the friction transmission belt in any one of Claims 1-11 including the coating | coated process which coat | covers a friction transmission surface with the thermal radiation layer precursor containing a heat conductive metal particle.   The friction transmission according to claim 12, further comprising a coating step of coating the friction transmission surface with a rubber composition containing a rubber component and heat conductive metal particles, and a vulcanization step of vulcanizing the rubber composition coated with the friction transmission surface. A method for manufacturing a belt.   The manufacturing method according to claim 13, wherein in the covering step, a liquid rubber composition containing a rubber component and thermally conductive metal particles is adhered to the friction transmission surface. The manufacturing method according to claim 13, wherein in the covering step, a sheet formed of a rubber composition containing a rubber component and thermally conductive metal particles is laminated on the friction transmission surface.