WO2017179690A1

WO2017179690A1 - Friction transmission belt

Info

Publication number: WO2017179690A1
Application number: PCT/JP2017/015262
Authority: WO
Inventors: 久登石黒; 拓也友田
Original assignee: 三ツ星ベルト株式会社
Priority date: 2016-04-15
Filing date: 2017-04-14
Publication date: 2017-10-19

Abstract

The present invention relates to a friction transmission belt provided with an adhesive rubber layer which is in contact with at least a part of a core extending in the lengthwise direction of the belt, wherein the adhesive rubber layer is formed from a first vulcanized rubber composition containing a rubber component and a filler, the filler contains at least 30 parts of carbon black by mass and 0.1-15 part of silica by mass per 100 parts of the rubber component by mass, and the core has an overcoat layer on the surface formed from a second vulcanized rubber composition that contains a rubber component and silica.

Description

Friction transmission belt

The present invention relates to a friction transmission belt in which a friction transmission surface such as a V-belt or a V-ribbed belt is formed with a V-shaped slope, and more specifically, friction excellent in mechanical properties such as interface peeling resistance, wear resistance, and low friction coefficient. Related to transmission belt.

Conventionally, friction transmission belts such as V-belts, V-ribbed belts, and flat belts are known as transmission belts for transmitting power. A V-belt or V-ribbed belt having a friction transmission surface (V-shaped side surface) formed at a V angle is wound around a driving pulley and a driven pulley with tension applied between the V-shaped side surface and the V groove of the pulley. Rotates between two shafts in contact. In the process, power is transmitted using energy associated with friction generated by thrust between the V-shaped side surface and the pulley V groove. These friction transmission belts have a core body embedded in the rubber body (between the compressed rubber layer and the stretched rubber layer) along the longitudinal direction of the belt, and this core body transmits the power from the driving pulley to the driven pulley. Have a role to communicate. Moreover, in order to improve the adhesiveness between the core wire and the rubber, an adhesive rubber layer is usually provided.

The V-belt is covered with a low-edge type (raw edge V-belt), which is a rubber layer with an exposed friction transmission surface (V-shaped side surface), and a cover cloth covering the friction transmission surface (V-shaped side surface). There are also Wrapped types (wrapped V-belts), which are properly used depending on the application due to the difference in surface properties of the friction transmission surface (friction coefficient between the rubber layer and the cover cloth). The low edge type belt has a low edge cog V that has improved flexibility by providing cogs only on the lower surface (inner peripheral surface) of the belt or on both the lower surface (inner peripheral surface) and the upper surface (outer peripheral surface) of the belt. There is a belt.

The low edge V belt and the low edge cogged V belt are mainly used for driving general industrial machinery, agricultural machinery, and driving auxiliary machinery in automobile engines. As another application, there is a low edge cogged V belt called a transmission belt used in a belt type continuously variable transmission such as a motorcycle.

As shown in FIG. 1, the belt-type continuously variable transmission 30 is a device that wraps the friction transmission belt 1 around a drive pulley 31 and a driven pulley 32 to change the gear ratio steplessly. Each

pulley

31 and 32 is composed of

fixed pulley pieces

31a and 32a fixed in the axial direction and

movable pulley pieces

31b and 32b movable in the axial direction. These

fixed pulley pieces

31a and 32a and the movable pulley The

pulleys

31 and 32 formed by the

pieces

31b and 32b have a structure capable of continuously changing the width of the V groove. The transmission belt 1 has both end faces in the width direction formed of tapered surfaces whose inclinations coincide with the opposing faces of the V grooves of the

pulleys

31 and 32, and the opposing faces of the V grooves according to the changed width of the V grooves. It fits in any vertical position. For example, when the width of the V groove of the driving pulley 31 is narrowed and the width of the V groove of the driven pulley 32 is widened, the state shown in FIG. 1A is changed to the state shown in FIG. The transmission belt 1 moves above the V-groove on the drive pulley 31 side, and below the V-groove on the driven pulley 32 side, and the wrapping radius around each

pulley

31 and 32 changes continuously to change the gear ratio. Can change steplessly. The speed change belt used in such applications is used in a severe layout under a high load while the belt is largely bent. In other words, not only the rotational rotation of the drive pulley and the driven pulley between two axes, but also the severe movement in high load environment such as the movement in the pulley radial direction and the bending motion repeated by the continuous change of the winding radius. Specific design is made to withstand.

Therefore, one of the important factors responsible for the durability of such a friction transmission belt such as a transmission belt is the resistance to side pressure received from the pulley. Conventionally, as a prescription for improving the side pressure resistance, a rubber composition having a large mechanical property reinforced by blending short fibers or the like is used for the compression rubber layer and the stretch rubber layer. On the other hand, if the mechanical properties of the adhesive rubber layer are excessively increased, the bending fatigue resistance is lowered. Therefore, a rubber composition having relatively small mechanical properties is used as the adhesive rubber layer.

For example, in Patent Document 1, the rubber hardness of at least one of the stretch rubber layer and the compression rubber layer is set to 90 to 96 °, and the rubber hardness of the adhesive rubber layer is set to 83 to 89 °. In the layer, a transmission V-belt in which aramid short fibers are oriented in the belt width direction is disclosed. In this document, cracks and separation (peeling) of each rubber layer and cord are prevented from occurring at an early stage, side pressure resistance is improved, and high load transmission capability is improved. Further, as the adhesive rubber layer, a rubber composition containing 100 parts by mass of chloroprene rubber, 40 to 60 parts by mass of a reinforcing filler (carbon black), and 5 to 30 parts by mass of silica is described. It is described that when the amount is less than 5 parts by mass, the effect of enhancing the adhesive force is almost lost. In addition, the detail of the adhesive rubber layer in an Example is unknown.

However, from the viewpoint of the composition design of such a rubber composition, the following problems (1) to (4) occur as the belt travels in a high load environment and cause a decrease in durability (life). Concerned.

(1) When the adhesiveness between the core wire and the adhesive rubber layer is low, the core wire and the adhesive rubber layer are peeled off.
(2) If the friction coefficient of the contact surface (transmission surface) with the pulley of the belt is high, the belt does not move smoothly, and the belt is likely to be deformed (particularly, buckling called dishing).
(3) A shear stress is generated inside the belt as the belt moves in the radial direction of the pulley and is deformed (buckling), and in particular, an interface having a difference in mechanical properties (in this case, a compressed rubber layer or a stretched rubber layer) And the adhesive rubber layer), shear stress tends to concentrate, and interface peeling (cracking) occurs.
(4) The contact surface (transmission surface) of the belt with the pulley is worn by sliding with the pulley.

In other words, in order to obtain high durability (long life) to withstand the severe movement of belts under high load environment, a unique design that satisfies all these characteristics as well as side pressure resistance is required. It is necessary. In particular, with regard to the adhesive rubber layer, a formulation for solving problems such as adhesion between the core wire and the adhesive rubber layer and interfacial peeling due to concentration of shear stress has been studied.

Regarding the adhesion between the core wire and the adhesive rubber layer, there is a prior art in which silica having high adhesion is blended as a reinforcing material. For example, Patent Document 2 discloses an organic peroxidation of a rubber composition in which 20 to 70 parts by mass of silica and 1 to 10 parts by mass of carbon black are blended with 100 parts by mass of a rubber component containing an ethylene-α-olefin elastomer. A power transmission belt composed of a cross-linked product is disclosed.

Further, in Patent Document 3, as a rubber composition for coating fibers constituting the core of a power transmission belt, 1 to 100 of silica is used with respect to 100 parts by mass of an ethylene-α-olefin-diene copolymer. There is disclosed a first rubber composition containing 1 part by weight, 0.01 to 15 parts by weight of a silane coupling agent and 0.1 to 30 parts by weight of a filler such as carbon black. As a rubber composition for coating or embedding a coated fiber, 1 to 100 parts by mass of silica and 1 to 100 parts by mass of a filler such as carbon black with respect to 100 parts by mass of an ethylene-α-olefin-diene copolymer. A second rubber composition containing parts is disclosed. In the examples of this document, as the first rubber composition, a composition containing 5 parts by mass of carbon black and 20 parts by mass of hydrous silica with respect to 100 parts by mass of EPDM was prepared, and as the second rubber composition, 100 parts by mass of EPDM. A composition containing 35 parts by mass of carbon black and 20 parts by mass of hydrous silica is prepared.

However, these methods of compounding silica as a reinforcing material increase the adhesion, but compared to other reinforcing materials such as carbon black, they have better mechanical properties such as interfacial debonding resistance, wear resistance, and low friction coefficient. Is disadvantageous. The reason for this is that if silica is compounded in a large amount, processing such as kneading becomes difficult, so the compounding amount is limited, and the mechanical properties of the adhesive rubber layer cannot be sufficiently improved. That is, the mechanical properties of the adhesive rubber layer cannot be improved to such a level that the difference in mechanical properties between the compressed rubber layer or the stretched rubber layer and the adhesive rubber layer can be reduced to prevent interface peeling. Silica cannot increase the friction coefficient sufficiently. In addition, the rubber composition containing silica has lower wear resistance than other reinforcing materials. Further, when a large amount of silica is blended, the pulley is worn during belt running, and is particularly noticeable when the pulley is made of a soft material such as aluminum.

On the other hand, in Patent Document 4, as an adhesive rubber layer of a rubber V-belt, 1 to 20 parts by mass of a metal oxide vulcanizing agent, 5 to 30 parts by mass of silica, and 15 to 15 parts of reinforcing filler with respect to 100 parts by mass of chloroprene rubber. A rubber composition comprising 50 parts by weight and 2-10 parts by weight of bismaleimide is disclosed. In an example of this document, an adhesive rubber composition containing 35 parts by mass of carbon black, 25 parts by mass of silica, and 2-8 parts by mass of bismaleimide with respect to 100 parts by mass of chloroprene rubber was prepared, and bismaleimide was added to the adhesive rubber layer. It is described that, when blended, the elastic modulus is increased by the effect of increasing the crosslinking density, the compression set is small, and the fatigue resistance is excellent.

However, even this adhesive rubber layer is not sufficient for the recent demand for higher load environments, and when the amount of bismaleimide is increased and the hardness is excessively increased, the bending fatigue resistance is lowered.

That is, in the prior art, as in the belts of Patent Documents 1 to 4, although means for solving each problem has been proposed, it can withstand severe movement in a high load environment such as a transmission belt. It cannot be said that all the necessary characteristics are satisfied. Specifically, in the conventional technology, while maintaining the adhesion between the adhesive rubber layer and the core wire, the mechanical properties are ensured (interfacial debonding resistance (distribution of shear stress) and wear resistance are satisfied), and the pulley Specific product design that can suppress wear has not been realized.

Japanese Unexamined Patent Publication No. 10-238596 Japanese Unexamined Patent Publication No. 2008-261473 Japanese Unexamined Patent Publication No. 2012-177068 Japanese Unexamined Patent Publication No. 61-290255

An object of the present invention is to provide a friction transmission belt capable of suppressing peeling and cracking of an interlayer and a core body and suppressing wear of a belt and a pulley even in a severe situation in a high load environment such as a transmission belt. .

Another object of the present invention is to provide a friction transmission belt capable of improving bending fatigue resistance.

As a result of intensive studies to achieve the above-mentioned problems, the inventors have formed an adhesive rubber layer of a friction transmission belt with a vulcanized rubber composition containing a rubber component and carbon black and silica in a predetermined ratio, and By covering the surface of the core with an overcoat layer made of a vulcanized rubber composition containing a rubber component and silica, the layers and cores can be peeled even in harsh conditions such as a transmission belt. The present invention has been completed by finding that it is possible to suppress cracks and cracks and to suppress wear of the belt and pulley.

That is, the friction transmission belt of the present invention is a friction transmission belt provided with an adhesive rubber layer in contact with at least a part of a core extending in the longitudinal direction of the belt, and the adhesive rubber layer includes a rubber component and a filler. The filler comprises 30 parts by mass or more of carbon black and 0.1 to 15 parts by mass of silica with respect to 100 parts by mass of the rubber component, and the core is a rubber component. And an overcoat layer formed on the surface of the second vulcanized rubber composition containing silica. In the first vulcanized rubber composition, the proportion of the carbon black may be 30 to 60 parts by mass with respect to 100 parts by mass of the rubber component. The proportion of silica in the first vulcanized rubber composition may be 10 to 30 parts by mass with respect to 100 parts by mass of the carbon black. The ratio of silica in the second vulcanized rubber composition may be 10 parts by mass or more (particularly 15 to 50 parts by mass) with respect to 100 parts by mass of the rubber component. The average thickness of the overcoat layer may be 5 to 30 μm. The rubber component of the first vulcanized rubber composition and / or the second vulcanized rubber composition may be chloroprene rubber. The core may include a twisted cord including a polyester fiber and / or a polyamide fiber.

In the present invention, the adhesive rubber layer of the friction transmission belt is formed of a vulcanized rubber composition containing a rubber component and carbon black and silica in a predetermined ratio, and the surface of the core body is vulcanized containing the rubber component and silica. It is covered with an overcoat layer formed of a rubber composition. Therefore, the adhesive rubber layer is specialized for the stress dispersion function due to high mechanical properties (higher elastic modulus), and the core overcoat layer is specialized for the adhesion function. As a result, even in harsh conditions in a high load environment such as a transmission belt, it is possible to suppress peeling and cracking of the interlayer and core, and to suppress wear of the belt and pulley. Furthermore, by adjusting the proportion of carbon black in the adhesive rubber layer to 60 parts by mass or less with respect to 100 parts by mass of the rubber component, the bending fatigue resistance can also be improved.

FIG. 1 is a schematic diagram for explaining a speed change mechanism of a belt type continuously variable transmission. FIG. 2 is a schematic perspective view showing an example of the friction transmission belt of the present invention. FIG. 3 is a schematic sectional view of the friction transmission belt of FIG. 2 cut in the belt longitudinal direction. FIG. 4 is a schematic diagram for explaining a durability running test of the friction transmission belt in the embodiment.

[Structure of friction transmission belt]
In the friction transmission belt of the present invention, the adhesive rubber layer is formed of a first vulcanized rubber composition containing a rubber component and a filler containing carbon black and a relatively small amount of silica, and the surface of the core is What is necessary is just to coat | cover with the overcoat layer formed with the 2nd vulcanized rubber composition containing a rubber component and a silica. Usually, the friction transmission belt of the present invention includes a core extending in the longitudinal direction of the belt, an adhesive rubber layer in which the core is embedded, a compression rubber layer formed on one surface of the adhesive rubber layer, and the adhesive And a stretched rubber layer formed on the other surface of the rubber layer.

Examples of the friction transmission belt of the present invention include a V belt [wrapped V belt, low edge V belt, low edge cogged V belt (a low edge cogged V belt having a cog formed on the inner peripheral side of the low edge V belt, a low edge V belt). Low edge double cogged V-belt in which cogs are formed on both the inner peripheral side and the outer peripheral side)], V-ribbed belt, flat belt and the like. Among these friction transmission belts, a V belt or a V-ribbed belt in which the friction transmission surface is inclined in a V shape (at a V angle) is preferable because it receives a large lateral pressure from the pulley. The low edge cogged V-belt is particularly preferable because it is used in a belt-type continuously variable transmission that requires a high degree of fuel economy.

FIG. 2 is a schematic perspective view showing an example of the friction transmission belt (low edge cogged V belt) of the present invention, and FIG. 3 is a schematic cross-sectional view of the friction transmission belt of FIG. 2 cut in the belt longitudinal direction.

In this example, the friction transmission belt 1 has a plurality of cogs 1a formed at predetermined intervals along the longitudinal direction of the belt (A direction in the drawing) on the inner peripheral surface of the belt main body. The cross-sectional shape of the cog portion 1a in the longitudinal direction is substantially semicircular (curved or corrugated), and the cross-sectional shape in the direction orthogonal to the longitudinal direction (width direction or B direction in the figure) is a table. Shape. That is, each cog 1a protrudes from the cog bottom 1b in a cross section in the A direction (FIG. 3) in a substantially semicircular shape in the belt thickness direction. The friction transmission belt 1 has a laminated structure, and the reinforcing cloth 2, the stretch rubber layer 3, the adhesive rubber layer 4, and the compression from the belt outer peripheral side toward the inner peripheral side (side where the cog portion 1 a is formed). A rubber layer 5 and a reinforcing cloth 6 are sequentially laminated. The cross-sectional shape in the belt width direction is a trapezoidal shape in which the belt width decreases from the belt outer peripheral side toward the inner peripheral side. Furthermore, a core body 4a is embedded in the adhesive rubber layer 4, and the cog 1a is formed on the compressed rubber layer 5 by a cog-molding mold.

[Adhesive rubber layer]
The adhesive rubber layer (adhesive layer) is provided in contact with at least a part of the core body for the purpose of bonding the core body and a rubber material for forming a belt. In the present invention, the adhesive rubber layer is formed of a vulcanized rubber composition containing a rubber component and a filler.

(Rubber component)
Examples of the rubber component include known vulcanizable or crosslinkable rubber components and / or elastomers such as diene rubbers (for example, natural rubber, isoprene rubber, butadiene rubber, chloroprene rubber (CR), styrene butadiene rubber (SBR), Water of the diene rubbers such as vinylpyridine-styrene-butadiene copolymer rubber, acrylonitrile butadiene rubber (nitrile rubber); hydrogenated nitrile rubber (including mixed polymer of hydrogenated nitrile rubber and unsaturated carboxylic acid metal salt) Additives, etc.], olefin rubber [eg, ethylene-α-olefin rubber (ethylene-α-olefin elastomer), polyoctenylene rubber, ethylene-vinyl acetate copolymer rubber, chlorosulfonated polyethylene rubber, alkylated chloro Sulfonated polyethylene rubber, etc.] Examples thereof include chlorohydrin rubber, acrylic rubber, silicone rubber, urethane rubber, and fluorine rubber. These rubber components can be used alone or in combination of two or more.

Among these rubber components, an ethylene-α-olefin elastomer (ethylene-propylene copolymer (EPM), ethylene-propylene-diene terpolymer ( Ethylene-α-olefin rubbers such as EPDM) and chloroprene rubber are widely used, especially when used in high load environments such as transmission belts, mechanical strength, weather resistance, heat resistance, cold resistance, oil resistance, adhesion, etc. From the viewpoint of excellent balance, chloroprene rubber and EPDM are preferable. Furthermore, chloroprene rubber is particularly preferable from the viewpoint of excellent wear resistance in addition to the above characteristics. The chloroprene rubber may be a sulfur-modified type or a non-sulfur-modified type.

When the rubber component contains chloroprene rubber, the proportion of the chloroprene rubber in the rubber component may be about 50% by mass (especially 80 to 100% by mass), and 100% by mass (chloroprene rubber only) is particularly preferable.

(Filler)
In the present invention, carbon black is included as a filler in order to dramatically improve fatigue fracture resistance and wear resistance. The average particle size of carbon black is, for example, about 5 to 200 nm, preferably about 10 to 150 nm, more preferably about 15 to 100 nm. From the viewpoint of high reinforcing effect, carbon black having a small particle size may be used. It may be about 38 nm, preferably 10 to 35 nm, more preferably about 15 to 30 nm. Examples of the carbon black having a small particle diameter include SAF, ISAF-HM, ISAF-LM, HAF-LS, HAF, and HAF-HS. These carbon blacks can be used alone or in combination.

In the present invention, the ratio of the carbon black is 30 parts by mass or more with respect to 100 parts by mass of the rubber component. Carbon black can suppress a decrease in workability even when blended in a large amount as compared with silica. Therefore, compared with a conventional adhesive rubber layer containing a large amount of silica, the mechanical properties (elastic modulus) of the adhesive rubber layer can be improved, so that the friction coefficient of the adhesive rubber layer can be reduced. Furthermore, the adhesive rubber layer containing a relatively large amount of carbon black has a smaller difference in mechanical properties from the compressed rubber layer (or stretched rubber layer), and the belt undergoes shear stress due to severe movement during belt running in a high load environment. Even if it receives, the interface of an adhesive rubber layer and a compression rubber layer (or extension rubber layer) does not become a concentrated point of shear stress, and interface peeling (crack) does not occur easily. Furthermore, since the rubber composition containing carbon black has higher wear resistance than silica, the wear resistance of the adhesive rubber layer can be improved.

Further, the ratio of the carbon black may be 100 parts by mass or less with respect to the rubber component from the viewpoint of suppressing a decrease in bending fatigue resistance. Further, the proportion of carbon black is preferably 30 to 80 parts by weight (particularly 30 to 60 parts by weight), particularly preferably 40 to 60 parts by weight (particularly 45 to 60 parts by weight), based on 100 parts by weight of the rubber component. It may be about 50 to 70 parts by mass (particularly 55 to 65 parts by mass). If the proportion of carbon black is too small, the elastic modulus may be insufficient and the fatigue fracture resistance and wear resistance may be reduced. If it is too large, the elastic modulus will be too high and the bending fatigue resistance may be reduced. There is.

In the present invention, a relatively small amount of silica is further contained as a filler from the viewpoint that the adhesive property of the adhesive rubber layer can be improved without deteriorating the mechanical properties of the adhesive rubber layer. Silica is a fine, bulky white powder formed of silicic acid and / or silicate, and has a plurality of silanol groups on its surface, so that it can be chemically bonded to the rubber component.

Silica includes dry silica, wet silica, surface-treated silica, and the like. Silica can also be classified into, for example, dry process white carbon, wet process white carbon, colloidal silica, precipitated silica, and the like according to the classification in the production method. These silicas can be used alone or in combination of two or more. Of these, wet white carbon containing hydrous silicic acid as a main component is preferable because it has many surface silanol groups and strong chemical bonding with rubber.

The average particle diameter of silica is, for example, about 1 to 1000 nm, preferably 3 to 300 nm, more preferably 5 to 100 nm (particularly 10 to 50 nm). If the particle size of the silica is too large, the mechanical properties of the adhesive rubber layer may be reduced, and if it is too small, it may be difficult to uniformly disperse.

Silica may be non-porous or porous, but the nitrogen adsorption specific surface area by the BET method is, for example, 50 to 400 m ² / g, preferably 70 to 350 m ² / g, more preferably 100. It may be about ˜300 m ² / g (especially 150 to 250 m ² / g). If the specific surface area is too large, it may be difficult to uniformly disperse, and if the specific surface area is too small, the mechanical properties of the adhesive rubber layer may be reduced.

The proportion of silica is a small amount compared to the proportion blended in the conventional adhesive rubber layer in order to improve the adhesiveness. That is, in the present invention, since the overcoat layer of the core includes silica, the adhesive rubber layer does not require a large amount of silica. In the present invention, since the overcoat layer contains silica and the adhesive rubber layer contains silica in a small proportion, the mechanical properties and adhesiveness of the adhesive rubber layer, which are contradictory properties (for example, adhesiveness to the core), In particular, the adhesiveness can be improved to a high degree.

The specific proportion of silica is, for example, 0.1 to 15 parts by mass (for example, 0.1 to 10 parts by mass), preferably 1 to 14 parts by mass, and more preferably 3 to 13 parts per 100 parts by mass of the rubber component. About mass parts (particularly 5 to 12 mass parts). If the proportion of silica is too small, the effect of improving the adhesiveness may not be exhibited. If the proportion of silica is too large, mechanical properties such as interfacial peel resistance, wear resistance, and low friction coefficient may be deteriorated.

Further, the ratio of silica is about 40 parts by mass or less with respect to 100 parts by mass of carbon black, for example, 5 to 35 parts by mass, preferably 10 to 30 parts by mass, and more preferably about 15 to 25 parts by mass. .

The filler may further contain a conventional filler. Examples of conventional fillers include clay, calcium carbonate, talc, and mica. These conventional fillers can be used alone or in combination of two or more.

The ratio of carbon black to the whole filler may be 50% by mass or more, preferably 60% by mass or more, more preferably 70% by mass or more (particularly 80% by mass or more), and 90% by mass. % Or more (particularly 99.9% by mass or more). If the proportion of carbon black is too small, the mechanical properties of the adhesive rubber layer may be reduced.

The proportion (total proportion) of the filler is, for example, about 30 to 100 parts by weight, preferably 40 to 80 parts by weight, more preferably 50 to 70 parts by weight (particularly 55 to 65 parts by weight) with respect to 100 parts by weight of the rubber component. It is. If the proportion of the filler is too small, the wear resistance may decrease due to a decrease in the elastic modulus. Conversely, if it is too large, the elastic modulus will be too high and heat will be generated, and the stretched rubber layer and the compressed rubber layer will crack. May occur early.

(Additive)
The rubber composition for forming the adhesive rubber layer includes a vulcanizing agent or a crosslinking agent (or a crosslinking agent system), a co-crosslinking agent, a vulcanization aid, a vulcanization accelerator, and a vulcanization retarder as necessary. , Metal oxides (eg, zinc oxide, magnesium oxide, calcium oxide, barium oxide, iron oxide, copper oxide, titanium oxide, aluminum oxide), softeners (oils such as paraffin oil and naphthenic oil), processing Agent or processing aid (fatty acid such as stearic acid, fatty acid metal salt such as stearic acid metal salt, fatty acid amide such as stearic acid amide, wax, paraffin, etc.), adhesion improver [resorcin-formaldehyde cocondensate (RF condensation) Products), amino resins (condensates of nitrogen-containing cyclic compounds and formaldehyde, such as hexamethylol melamine, hexaalkoxymethyl methy Melamine resins such as min (hexamethoxymethyl melamine, hexabutoxymethyl melamine, etc.), urea resins such as methylol urea, benzoguanamine resins such as methylol zoguanamine resin, etc., and their condensates (resorcin-melamine-formaldehyde co-condensation) Etc.), short fibers (polyester short fibers, aramid short fibers, etc.), anti-aging agents (antioxidants, thermal anti-aging agents, anti-bending cracking agents, anti-ozone degradation agents, etc.), colorants, tackifiers An agent, a plasticizer, a lubricant, a coupling agent (such as a silane coupling agent), a stabilizer (such as an ultraviolet absorber and a heat stabilizer), a flame retardant, and an antistatic agent may be included. The metal oxide may act as a crosslinking agent. In the adhesion improver, the resorcin-formaldehyde cocondensate and amino resin may be an initial condensate (prepolymer) of a nitrogen-containing cyclic compound such as resorcin and / or melamine and formaldehyde.

As the vulcanizing agent or the crosslinking agent, conventional components can be used depending on the type of rubber component. For example, the metal oxide (magnesium oxide, zinc oxide, etc.), organic peroxide (diacyl peroxide, peroxyester) And dialkyl peroxide), sulfur vulcanizing agents, and the like. Examples of the sulfur-based vulcanizing agent include powdered sulfur, precipitated sulfur, colloidal sulfur, insoluble sulfur, highly dispersible sulfur, sulfur chloride (sulfur monochloride, sulfur dichloride, etc.), and the like. These crosslinking agents or vulcanizing agents may be used alone or in combination of two or more. When the rubber component is chloroprene rubber, a metal oxide (magnesium oxide, zinc oxide, etc.) may be used as a vulcanizing agent or a crosslinking agent. The metal oxide may be used in combination with other vulcanizing agents (such as sulfur-based vulcanizing agents), and the metal oxide and / or sulfur-based vulcanizing agent may be used alone or in combination with a vulcanization accelerator. May be used.

The proportion of the vulcanizing agent can be selected from a range of about 1 to 20 parts by mass with respect to 100 parts by mass of the rubber component depending on the types of the vulcanizing agent and the rubber component. For example, the ratio of the organic peroxide as the vulcanizing agent is 1 to 8 parts by weight, preferably 1.5 to 5 parts by weight, and more preferably about 2 to 4.5 parts by weight with respect to 100 parts by weight of the rubber component. The ratio of the metal oxide is 1 to 20 parts by weight, preferably 3 to 17 parts by weight, more preferably 5 to 15 parts by weight (particularly 7 to 13 parts by weight) with respect to 100 parts by weight of the rubber component. ) Select from a range of degrees.

Examples of the co-crosslinking agent (crosslinking aid or co-vulcanizing agent co-agent) include known crosslinking aids such as polyfunctional (iso) cyanurates [for example, triallyl isocyanurate (TAIC), triallyl cyanurate ( TAC), etc.], polydienes (eg, 1,2-polybutadiene, etc.), metal salts of unsaturated carboxylic acids [eg, zinc (meth) acrylate, magnesium (meth) acrylate, etc.], oximes (eg, quinonedi) Oximes, etc.), guanidines (eg, diphenylguanidine, etc.), polyfunctional (meth) acrylates (eg, ethylene glycol di (meth) acrylate, butanediol di (meth) acrylate, trimethylolpropane tri (meth) acrylate, etc.), Bismaleimides (aliphatic bismaleimides such as N, N′-1,2 Ethylene dimaleimide, 1,6′-bismaleimide- (2,2,4-trimethyl) cyclohexane, etc .; arene bismaleimide or aromatic bismaleimide, such as N, N′-m-phenylene dimaleimide, 4-methyl- 1,3-Phenylene resin maleimide, 4,4′-diphenylmethane dimaleimide, 2,2-bis [4- (4-maleimidophenoxy) phenyl] propane, 4,4′-diphenyl ether dimaleimide, 4,4′-diphenyl Sulfone dimaleimide, 1,3-bis (3-maleimidophenoxy) benzene and the like. These crosslinking aids can be used alone or in combination of two or more. Of these crosslinking aids, bismaleimides (arene bismaleimides such as N, N'-m-phenylene dimaleimide or aromatic bismaleimides) are preferred. The addition of bismaleimides can increase the degree of crosslinking and prevent adhesive wear and the like.

The ratio of the co-crosslinking agent (crosslinking aid) can be selected from the range of about 0.01 to 10 parts by mass, for example, 0.1 to 10 parts by mass (for example 0 .3 to 8 parts by mass), preferably about 0.5 to 6 parts by mass (especially 1 to 5 parts by mass).

Examples of the vulcanization accelerator include thiuram accelerators [for example, tetramethylthiuram monosulfide (TMTM), tetramethylthiuram disulfide (TMTD), tetraethylthiuram disulfide (TETD), tetrabutylthiuram disulfide (TBTD). ), Dipentamethylene thiuram tetrasulfide (DPTT), N, N′-dimethyl-N, N′-diphenyl thiuram disulfide, etc.], thiazole accelerators (eg, 2-mercaptobenzothiazol, 2 -Zinc salts of mercaptobenzothiazol, 2-mercaptothiazoline, dibenzothiazyl disulfide, 2- (4'-morpholinodithio) benzothiazole, etc.)], sulfenamide accelerators (for example, N-cyclohexyl) -2-Benzothiazils Phenamide (CBS), N, N′-dicyclohexyl-2-benzothiazylsulfenamide, etc.], guanidines (diphenylguanidine, di-tolylguanidine, etc.), urea-based or thiourea accelerators (for example, ethylenethiourea, etc.) ), Dithiocarbamates, xanthates and the like. These vulcanization accelerators can be used alone or in combination of two or more. Of these vulcanization accelerators, TMTD, DPTT, CBS and the like are widely used.

The proportion of the vulcanization accelerator is, for example, 0.1 to 15 parts by mass, preferably 0.3 to 10 parts by mass, and more preferably 0.5 to 5 parts by mass in terms of solid content with respect to 100 parts by mass of the rubber component. It may be about a part.

The ratio of the softening agent (oils such as naphthenic oil) is, for example, about 1 to 30 parts by mass, preferably about 3 to 20 parts by mass (eg 5 to 10 parts by mass) with respect to 100 parts by mass of the total amount of rubber components. There may be. Further, the ratio of the processing agent or processing aid (eg, stearic acid) is 10 parts by mass or less (for example, 0 to 10 parts by mass), preferably 0.1 to 5 parts by mass with respect to 100 parts by mass of the rubber component. More preferably, it may be about 0.3 to 3 parts by mass (particularly 0.5 to 2 parts by mass).

The ratio of the adhesion improver (resorcin-formaldehyde cocondensate, hexamethoxymethylmelamine, etc.) is 0.1 to 20 parts by weight, preferably 0.3 to 10 parts by weight, based on 100 parts by weight of the rubber component. Preferably, it may be about 0.5 to 5 parts by mass (1 to 3 parts by mass).

The proportion of the antioxidant is, for example, 0.5 to 15 parts by weight, preferably 1 to 10 parts by weight, more preferably 2.5 to 7.5 parts by weight (particularly 3 parts by weight) with respect to 100 parts by weight of the total amount of rubber components. About 7 parts by mass).

(Characteristics of adhesive rubber layer)
The mechanical properties of the adhesive rubber layer can be appropriately selected according to the required performance. For example, the rubber hardness is, for example, 75 to 90 °, preferably 80 to 88 °, more preferably, by a method based on JIS K6253 (2012). It may be about 82 to 86 °. Further, an adhesive rubber layer having a high rubber hardness may be formed. For example, the rubber hardness may be adjusted to about 84 to 90 ° by blending a large amount of filler.

The average thickness of the adhesive rubber layer can be appropriately selected depending on the type of belt, and may be, for example, about 0.4 to 3 mm, preferably about 0.6 to 2.2 mm, and more preferably about 0.8 to 1.4 mm. Good.

[Core]
In the present invention, the surface of the core body is covered with an overcoat layer formed of a vulcanized rubber composition containing a rubber component and silica, from the viewpoint that the adhesiveness with the adhesive rubber layer can be improved.

(Overcoat layer)
In this invention, since the overcoat layer laminated | stacked on the outermost surface of the core body contains a silica, the adhesiveness of an adhesive rubber layer and a core body can be improved. As the silica, silica exemplified as the silica of the adhesive rubber layer can be used. The said silica can be used individually or in combination of 2 or more types. The preferable type, average particle diameter, and specific surface area of silica are also the same as those of the adhesive rubber layer.

The proportion of silica may be 10 parts by mass or more (for example, 10 to 50 parts by mass) with respect to 100 parts by mass of the rubber component, for example, 15 to 50 parts by mass, preferably 25 to 50 parts by mass, and more preferably 30 parts. About 45 parts by mass (particularly 35 to 45 parts by mass). If the ratio of silica is too small, there is a possibility that sufficient adhesion between the core and the adhesive rubber layer may not be ensured, and if it is too large, processability may decrease and it may be difficult to add to the rubber composition. There is.

The rubber component exemplified as the rubber component of the adhesive rubber layer can be used as the rubber component. The said rubber component can be used individually or in combination of 2 or more types. Among the rubber components, diene rubber (eg, chloroprene rubber, nitrile rubber, hydrogenated nitrile rubber, etc.), olefin rubber (eg, EPM, EPDM, chlorosulfonated polyethylene rubber, alkylated chlorosulfonated polyethylene rubber, etc.) Etc. are widely used. In addition, as a rubber component, the rubber component (especially chloroprene rubber) of the same or the same system as the adhesive rubber layer which embeds a core body can be used conveniently.

The vulcanized rubber composition forming the overcoat layer may further contain carbon black, if necessary. As the carbon black, the carbon black exemplified as the carbon black of the adhesive rubber layer can be used. The said carbon black can be used individually or in combination of 2 or more types. The preferred type of carbon black and the average particle size are also the same as those of the carbon black of the adhesive rubber layer.

The proportion of carbon black may be 50 parts by mass or less with respect to 100 parts by mass of the rubber component, for example, 35 parts by mass or less (for example, 5 to 35 parts by mass), preferably 30 parts by mass or less (for example, 20 parts by mass or less). ), More preferably 10 parts by mass or less (particularly 5 parts by mass or less). Further, the vulcanized rubber composition may not contain carbon black. If the ratio of carbon black is too large, the processability is lowered and it may be difficult to blend silica at a high concentration.

The vulcanized rubber composition forming the overcoat layer may further contain an isocyanate compound and / or an epoxy compound as a curing agent.

Examples of the isocyanate compound include 4,4′-diphenylmethane diisocyanate, tolylene 2,4-diisocyanate, polymethylene polyphenyl diisocyanate, hexamethylene diisocyanate, polyaryl polyisocyanate (for example, trade name “PAPI”), and the like. . These isocyanate compounds may be blocked polyisocyanates obtained by reacting a blocking agent such as phenols, tertiary alcohols, and secondary alcohols to block the isocyanate groups of the polyisocyanate.

Examples of the epoxy compound include a reaction product of a polyhydric alcohol such as ethylene glycol, glycerin and pentaerythritol, a polyalkylene glycol such as polyethylene glycol, and a halogen-containing epoxy compound such as epichlorohydrin, resorcin, and bis (4-hydroxyphenyl). ) Reaction products of polyhydric phenols such as dimethylmethane, phenol-formaldehyde resin, resorcinol-formaldehyde resin and halogen-containing epoxy compounds.

These curing agents can be used alone or in combination of two or more. Of these, isocyanate compounds are preferred.

The ratio of the curing agent is, for example, about 10 to 200 parts by mass, preferably about 30 to 150 parts by mass, and more preferably about 50 to 100 parts by mass with respect to 100 parts by mass of the rubber component.

In the vulcanized rubber composition forming the overcoat layer, fillers exemplified as fillers (fillers other than silica and carbon black) of the adhesive rubber layer and additives exemplified as additives can be used as necessary. . The said additive can be used individually or in combination of 2 or more types. The ratio of the additive is the same as that of the adhesive rubber layer. Of these, fillers, vulcanizing agents, co-vulcanizing agents, vulcanization accelerators, adhesion improvers, anti-aging agents, lubricants and the like are widely used. Typical compositions include rubber components, silica, RF condensates, and additives (eg, vulcanizing agents, co-curing agents, vulcanization accelerators, adhesion improvers, fillers, anti-aging agents, lubricants) It is a combination.

The average thickness of the overcoat layer is, for example, about 5 to 30 μm, preferably about 8 to 25 μm, and more preferably about 10 to 20 μm. In the present invention, since the overcoat layer is adjusted to such a thin wall, it can be presumed that even if the overcoat layer is specialized for the adhesion function, the shear stress is easily dispersed and the deterioration of the mechanical properties can be suppressed. If the overcoat layer is too thin, the adhesion between the core and the adhesive rubber layer may not be sufficiently secured, and if it is too thick, the bending fatigue resistance may be inferior.

(Anchor coat layer)
An anchor coat layer may be further interposed between the overcoat layer and the core body in order to improve the adhesion between the overcoat layer and the core body.

The anchor coat layer is not particularly limited as long as it is formed of a conventional adhesive component, and may be a single layer or a layer in which a plurality of layers are laminated. Among these, from the point which can improve the adhesiveness of an overcoat layer and a core, it intervenes between the 1st anchor coat layer which coat | covers the surface of a core, and a 1st anchor coat layer and an overcoat layer A combination with the second anchor coat layer is preferable.

The first anchor coat layer may be a layer formed with the curing agent exemplified in the section of the overcoat layer. As the curing agent, the same or the same type of curing agent (particularly an isocyanate compound) as the curing agent contained in the overcoat layer can be suitably used.

The average thickness of the first anchor coat layer is, for example, about 0.001 to 5 μm, preferably about 0.01 to 3 μm, and more preferably about 0.05 to 2 μm.

The second anchor coat layer may be formed of a cured product of RFL liquid. The RFL liquid contains resorcin (R), formaldehyde (F), and rubber or latex (L). Resorcin (R) and formaldehyde (F) may be contained in the form of these condensates (RF condensates). In particular, when the core body covered with the first anchor coat layer is a twisted cord, the second anchor coat layer forms a film on the first anchor coat layer, thereby improving the convergence of the twisted cord. . Furthermore, the second anchor coat layer can be firmly bonded to the overcoat layer, so that the overcoat layer can be firmly integrated from the first anchor coat layer.

The ratio (use ratio) of resorcin to formaldehyde can be selected from the range of the former / latter (molar ratio) = 1 / 0.1 to 1/5, for example, and a mixture of resole type and novolak type is produced. The molar ratio of the two is, for example, the former / the latter = 1 / 0.3 to 1/1, preferably 1 / 0.4 to 1 / 0.95, and more preferably 1 / 0.5 to 1 / 0.0. It may be about 9. If the proportion of formaldehyde is too large, there is a risk of contamination with residual formaldehyde. Conversely, if it is too small, the content of the resol-type RF condensate may be insufficient and the mechanical properties of the cured product may be deteriorated.

The rubber component constituting the latex is not particularly limited as long as it can impart flexibility to the core, and for example, the rubber component exemplified as the rubber component of the adhesive rubber layer can be used. The said rubber component can be used individually or in combination of 2 or more types. Of the rubber components, vinylpyridine-styrene-butadiene copolymer rubber is widely used.

The average thickness of the second anchor coat layer is, for example, about 1 to 30 μm, preferably 2 to 25 μm, and more preferably about 5 to 20 μm.

(Core)
The core body is not particularly limited as long as it has an overcoat layer containing a rubber component and silica on the surface, but normally, core wires (twisted cords) arranged at predetermined intervals in the belt width direction can be used. The cores are arranged to extend in the longitudinal direction of the belt, and are usually arranged to extend in parallel at a predetermined pitch in parallel with the longitudinal direction of the belt. The core wire only needs to be at least partially in contact with the adhesive rubber layer via the overcoat layer. The core rubber wire is embedded between the adhesive rubber layer and the stretch rubber layer. Any form of embedding the core wire and embedding the core wire between the adhesive rubber layer and the compressed rubber layer may be employed. Among these, the form in which the adhesive rubber layer embeds the core wire is preferable from the viewpoint that durability can be improved.

Examples of the fibers constituting the core wire include polyolefin fibers (polyethylene fibers, polypropylene fibers, etc.), polyamide fibers (polyamide 6 fibers, polyamide 66 fibers, polyamide 46 fibers, aramid fibers, etc.), polyalkylene arylate fibers [polyethylene. Terephthalate (PET) fiber, polyethylene naphthalate (PEN) fiber, etc., poly C _2-4 alkylene C _6-14 arylate fiber, etc.], vinylon fiber, polyvinyl alcohol fiber, polyparaphenylene benzobisoxazole (PBO) fiber, etc. Synthetic fibers; natural fibers such as cotton, hemp and wool; and inorganic fibers such as carbon fibers. These fibers can be used alone or in combination of two or more.

Among these fibers, from the viewpoint of high modulus, synthesis of polyester fibers (polyalkylene arylate fibers) mainly composed of C _2-4 alkylene arylates such as ethylene terephthalate and ethylene-2,6-naphthalate, aramid fibers, etc. Inorganic fibers such as fibers and carbon fibers are widely used, and polyester fibers (especially polyethylene terephthalate fibers and polyethylene naphthalate fibers) and polyamide fibers (particularly aramid fibers) are preferable. The fiber may be a multifilament yarn. The fineness of the multifilament yarn may be, for example, about 2000 to 10000 denier (particularly 4000 to 8000 denier). The multifilament yarn may contain, for example, 100 to 5,000, preferably 500 to 4,000, more preferably about 1,000 to 3,000 monofilament yarns.

As the core wire, usually 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, 0.5 to 3 mm, preferably 0.6 to 2 mm, more preferably about 0.7 to 1.5 mm. Good.

(Manufacturing method of core)
The method for producing the core is not particularly limited, and the surface of the untreated yarn (core wire body) forming the core may be covered with the overcoat layer by a conventional method. When the core body has the first anchor coat layer, the second anchor coat layer, and the overcoat layer, the core body performs the first treatment for forming the untreated yarn of the core wire and the first anchor coat layer. First treatment step for treating with an agent, second treatment step for treating with a second treatment agent for forming a second anchor coat layer, and third treatment for treating with a third treatment agent for forming an overcoat layer You may manufacture through a process.

In the first treatment step, the method for preparing the first treatment agent is not particularly limited, and usually the curing agent is dissolved in a solvent such as toluene or methyl ethyl ketone.

The method for treating the untreated yarn with the first treating agent is not particularly limited, and examples thereof include spraying, coating, and dipping. Of these treatment methods, immersion is widely used. The immersion time may be, for example, about 1 to 20 seconds, preferably about 2 to 15 seconds.

After the untreated yarn is treated with the first treating agent, it may be dried as necessary. The drying temperature may be, for example, about 100 to 250 ° C., preferably 110 to 220 ° C., more preferably 120 to 200 ° C. (especially 150 to 190 ° C.). The drying time may be, for example, about 10 seconds to 30 minutes, preferably about 30 seconds to 10 minutes, and more preferably about 1 to 5 minutes.

In the second treatment step, the second treatment agent usually contains water in many cases. The treatment method using the second treatment agent is the same as the treatment method using the first treatment agent. A preferable drying temperature may be about 150 to 250 ° C. (particularly 200 to 240 ° C.).

In the third treatment step, the method for preparing the third treatment agent is not particularly limited. Usually, the unvulcanized rubber composition is dissolved in a solvent such as toluene or methyl ethyl ketone, and the total solid content concentration is, for example, 1 to 20 masses. %, Preferably 2 to 15% by mass, more preferably 3 to 10% by mass. The treatment method using the third treatment agent is the same as the treatment method using the first treatment agent. A preferable drying temperature may be about 120 to 200 ° C. (especially 150 to 180 ° C.).

[Compressed rubber layer and stretched rubber layer]
The vulcanized rubber composition for forming the compressed rubber layer (inner rubber layer or inner layer) and the stretched rubber layer (back rubber layer or back layer) is similar to the vulcanized rubber composition of the adhesive rubber layer. Ingredients (chloroprene rubber, etc.), vulcanizing agents or crosslinking agents (metal oxides such as magnesium oxide and zinc oxide, sulfur-based vulcanizing agents such as sulfur), co-crosslinking agents or crosslinking aids (N, N'-m -Maleimide crosslinkers such as phenylene dimaleimide), vulcanization accelerators (TMTD, DPTT, CBS, etc.), fillers (carbon black, silica, etc.), softeners (oils such as naphthenic oil), processing agents or Processing aids (stearic acid, metal stearates, waxes, paraffins, etc.), anti-aging agents, adhesion improvers, fillers (clay, calcium carbonate, talc, mica, etc.), colorants, sticking An additive, a plasticizer, a coupling agent (such as a silane coupling agent), a stabilizer (such as an ultraviolet absorber and a heat stabilizer), a flame retardant, and an antistatic agent may be included.

Furthermore, the vulcanized rubber composition for forming the compressed rubber layer and the stretched rubber layer may contain short fibers.

As the short fibers, the fibers exemplified as the fibers constituting the core can be used. The short fiber formed with the said fiber can be used individually or in combination of 2 or more types. Among these short fibers, synthetic fibers and natural fibers, particularly synthetic fibers (polyamide fibers, polyalkylene arylate fibers, etc.), among others, are rigid and have high strength and modulus, and at least from the point that they tend to protrude on the surface of the compressed rubber layer. Short fibers including aramid fibers are preferred. Aramid short fibers also have high wear resistance. Aramid fibers are commercially available, for example, under the trade names “Conex”, “Nomex”, “Kevlar”, “Technola”, “Twaron”, and the like.

The average fiber diameter of the short fibers is 2 μm or more, for example, 2 to 100 μm, preferably 3 to 50 μm (for example 5 to 50 μm), more preferably 7 to 40 μm (particularly 10 to 30 μm). The average length of the short fibers is, for example, 1 to 20 mm (eg, 1.2 to 20 mm), preferably 1.3 to 15 mm (eg, 1.5 to 10 mm), more preferably 2 to 5 mm (particularly 2.5 to 4 mm). )

In order to suppress the compressive deformation of the belt against the pressure from the pulley, the short fiber may be oriented in the belt width direction and embedded in the adhesive rubber layer.

From the viewpoint of dispersibility and adhesion of the short fibers in the rubber composition, the short fibers may be subjected to adhesion treatment (or surface treatment) by a conventional method.

Furthermore, the short fibers may be protruded from the surface by polishing the surface (friction transmission surface). The average protruding height of the short fibers may be about 50 μm or more (for example, 50 to 200 μm).

In this rubber composition, as the rubber component, a rubber of the same type (diene rubber or the like) or the same type (chloroprene rubber or the like) as the rubber component of the rubber composition of the adhesive rubber layer is often used.

The proportions of the vulcanizing agent or crosslinking agent, co-crosslinking agent or crosslinking aid, vulcanization accelerator, softener, processing agent or processing aid, and anti-aging agent are the same as in the rubber composition of the adhesive rubber layer, respectively. You can select from a range. The proportion of short fibers can be selected from the range of about 5 to 50 parts by mass with respect to 100 parts by mass of the rubber component, and is usually 10 to 40 parts by mass, preferably 15 to 35 parts by mass, and more preferably 20 to 30 parts by mass. It may be about a part. Further, the ratio of the filler is about 1 to 100 parts by weight, preferably 3 to 50 parts by weight, and more preferably about 5 to 40 parts by weight with respect to 100 parts by weight of the rubber component.

The average thickness of the compressed rubber layer can be appropriately selected depending on the type of belt, and is, for example, about 2 to 25 mm, preferably about 3 to 16 mm, and more preferably about 4 to 12 mm. The thickness of the stretched rubber layer can be appropriately selected depending on the type of belt, and is, for example, about 0.8 to 10.0 mm, preferably about 1.2 to 6.5 mm, and more preferably about 1.6 to 5.2 mm.

[Reinforcing cloth]
When a reinforcing cloth is used in the friction transmission belt, the reinforcing cloth is not limited to a form in which the reinforcing cloth is laminated on the surface of the compressed rubber layer. For example, the reinforcing cloth is applied to the surface of the stretched rubber layer (the surface opposite to the adhesive rubber layer). It may be laminated, or may be a form in which a reinforcing layer is embedded in a compressed rubber layer and / or a stretched rubber layer (for example, a form described in Japanese Patent Application Laid-Open No. 2010-230146). The reinforcing cloth can be formed of, for example, a cloth material (preferably a woven cloth) such as a woven cloth, a wide angle sail cloth, a knitted cloth, and a non-woven cloth. If necessary, an adhesive treatment, for example, treatment with an RFL liquid (immersion treatment, etc.) ), Friction for rubbing adhesive rubber into the cloth material, or laminating (coating) the adhesive rubber and the cloth material, and then laminating on the surface of the compression rubber layer and / or the stretch rubber layer.

[Method of manufacturing friction transmission belt]
The manufacturing method of the friction transmission belt of the present invention is not particularly limited, and a conventional method can be used for the lamination process of each layer (the manufacturing method of the belt sleeve).

For example, in the case of a cogged V belt, a laminated body composed of a reinforcing cloth (under cloth) and a sheet for a compressed rubber layer (unvulcanized rubber) is arranged with teeth and grooves alternately with the reinforcing cloth down. Installed on a flat cogged mold, cog pad with the cog part formed by press-pressing at a temperature of 60-100 ° C (especially 70-80 ° C) (not completely vulcanized, in a semi-cured state) After producing a certain pad), both ends of the cog pad may be cut vertically from the top of the cog crest. Furthermore, an inner mother die in which teeth and grooves are alternately arranged is covered on a cylindrical mold, and a cog pad is wound around the teeth and the grooves, and a joint is formed at the top of the cog crest, and this is wound. After laminating the first adhesive rubber layer sheet (lower adhesive rubber: unvulcanized rubber) on the cog pad, the core is spun in a spiral shape, and the second adhesive rubber layer sheet (upper adhesive) Rubber: Same as the adhesive rubber layer sheet), a stretch rubber layer sheet (unvulcanized rubber), and a reinforcing cloth (upper cloth) may be wound in order to produce a molded body. After that, a jacket is put on and the mold is placed in a vulcanizing can and vulcanized at a temperature of about 120 to 200 ° C. (especially 150 to 180 ° C.) to prepare a belt sleeve. Cutting may be performed.

Hereinafter, the present invention will be described in more detail based on examples, but the present invention is not limited to these examples. In the following examples, the raw materials used in the examples and the measurement methods or evaluation methods for each physical property are shown below. Unless otherwise specified, “part” and “%” are based on mass.

[material]
Chloroprene rubber: “R22” manufactured by Tosoh Corporation
Carbon black: “Seast 3” manufactured by Tokai Carbon Co., Ltd.
Silica: “Ultrasil VN-3” manufactured by Evonik Degussa Japan Co., Ltd., specific surface area of 155 to 195 m ² / g
Naphthenic oil: “NS-900” manufactured by Idemitsu Kosan Co., Ltd.
Resorcin / formalin copolymer (resorcinol resin): resorcinol less than 20%, formalin less than 0.1% anti-aging agent: Seiko Chemical Co., Ltd. “Nonflex OD3”
Vulcanization accelerator TMTD: Tetramethylthiuram disulfide Aramid short fiber: “Conex short fiber” manufactured by Teijin Techno Products Limited, average fiber length 3 mm, average fiber diameter 14 μm, RFL solution (2.6 parts of resorcin, 37% A short fiber having a solid content of 6% by mass bonded with 1.4 parts of formalin, 17.2 parts of vinylpyridine-styrene-butadiene copolymer latex (manufactured by Nippon Zeon Co., Ltd., 78.8 parts of water). Polymeric MDI: Polyisocyanate, “MR-200” manufactured by Tosoh Corporation
VP latex: vinylpyridine-styrene-butadiene copolymer latex, manufactured by Nippon Zeon Co., Ltd. Core wire: 1,000 denier PET fiber with a 2 × 3 twist configuration, upper twist factor 3.0, lower twist factor 3 A twisted cord of 6,000 total denier twisted at 0.0.

[Measurement of physical properties of vulcanized rubber]
(1) Hardness The adhesive rubber layer sheet was press vulcanized at a temperature of 160 ° C. for 30 minutes to prepare a vulcanized rubber sheet (100 mm × 100 mm × 2 mm thickness). Hardness was measured according to JIS K6253 (2012) using a laminate of three vulcanized rubber sheets as a sample and using a durometer A type hardness tester.

(2) Abrasion A hollow rubber sheet having an inner diameter of 16.2 ± 0.05 mm is obtained from a vulcanized rubber sheet (50 mm × 50 mm × 8 mm thick) produced by press vulcanizing the adhesive rubber layer sheet at a temperature of 160 ° C. for 30 minutes. A cylindrical sample having a diameter of 16.2 ± 0.2 mm and a thickness of 6 to 8 mm was produced by cutting with a drill. According to JIS K6264 (2005), the wear amount of the vulcanized rubber was measured using a rotating cylindrical drum device (DIN abrasion tester) wound with a polishing cloth.

(3) Peel strength (adhesive strength with the core)
A plurality of core wires are arranged in parallel so that the width is 25 mm on one surface of the unvulcanized adhesive rubber layer sheet having a thickness of 4 mm, and canvas is laminated on the other surface. The adhesive rubber layer sheet and canvas were press vulcanized (temperature 160 ° C., time 30 minutes, pressure 2.0 MPa) to prepare strip samples (25 mm × 150 mm × 4 mm thickness) for a peel test. Then, according to JIS K6256 (2013), a peel test was performed at a tensile speed of 50 mm / min, and the peel force (vulcanized adhesive force) between the core wire and the adhesive rubber layer sheet was measured in a room temperature atmosphere. For the adhesive rubber layer sheet of this peel test, the formulation X (a formulation not containing silica) shown in Table 1 was used. Furthermore, the state of peeling was visually observed and evaluated according to the following criteria.

A: The rubber layer was broken while the interface between the adhesive rubber layer and the core wire was bonded.
B: Partial peeling occurred at the interface between the adhesive rubber layer and the core wire.
C: Peeling occurred completely at the interface between the adhesive rubber layer and the core wire.

[Durability test of belt]
As shown in FIG. 4, the endurance running test was performed using a two-axis running test machine including a driving (Dr.) pulley 22 having a diameter of 50 mm and a driven (Dn.) Pulley 23 having a diameter of 125 mm. A low-edge cogged V-belt 21 is hung on each

pulley

22, 23, the drive pulley 22 has a rotational speed of 5000 rpm, a load of 10 N · m is applied to the driven pulley 23, and the belt 21 is kept at an ambient temperature of 80 ° C for a maximum of 24 hours. I drove it. At this time, a misalignment of 0.5 ° was set between the driving pulley and the driven pulley. If the belt 21 traveled for 24 hours, it was determined that there was no problem with durability. Further, the belt side surface (the surface in contact with the pulley) after running was observed with a microscope to check for the presence of peeling of the core wire, and evaluated according to the following criteria.

A: No peeling of the core wire is observed.
B: Although peeling of the core wire was observed, there is no problem in practical use.
C: The core wire was peeled off to the extent that it was not practical.

In addition, the weight of the belt before traveling and the weight of the belt after traveling were measured with an electronic balance, respectively, and the difference in weight was calculated as the amount of wear of the belt in the endurance traveling. Further, the pulley after running was visually observed to check for pulley wear. Finally, the overall evaluation of the durability running test was judged according to the following criteria.

A: Neither pulley abrasion nor core wire peeling is observed.
B: Wear of the pulley or peeling of the core wire occurs, but there is no practical problem.
C: Either wear of the pulley or peeling of the core wire occurs to a degree that cannot be used.

Examples 1 to 8 and Comparative Examples 1 to 4
(Formation of rubber layer)
The rubber compositions in Table 1 (adhesive rubber layer) and Table 2 (compressed rubber layer and stretched rubber layer) were each kneaded using a known method such as a Banbury mixer, and the kneaded rubber was passed through a calender roll. Rolled rubber sheets (adhesive rubber layer sheet, compression rubber layer sheet, stretch rubber layer sheet). Table 1 shows the physical properties of the vulcanized rubber for the rubber composition used for the adhesive rubber layer.

(Core bonding process)
The core wire was immersed in the first treatment agent (pretreatment liquid) shown in Table 3, and then heat treated at 180 ° C. for 4 minutes. Next, it was immersed in the 2nd processing agent (RFL liquid) shown in Table 4, and heat-processed at 230 degreeC for 2 minute (s). Furthermore, using the 3rd processing agent containing the rubber composition A or B shown in Table 5, the 3rd process (overcoat process) shown in Table 6 was performed. By these treatments, the solid contents contained in the first treatment agent, the second treatment agent, and the third treatment agent are respectively converted into the first anchor coat layer, the second anchor coat layer, and the overcoat layer film (three layers). A core wire attached as a coating was produced. That is, in the core wire after the adhesion treatment, the solid content contained in the third treatment agent is disposed as the outermost layer (overcoat layer) film. The thickness of the overcoat layer was 10 to 20 μm.

Table 5 shows the measured values of the peel force (vulcanized adhesive force) and the peel strength of the core wire to which the film is adhered by these adhesion treatments as a result of the peel test with the rubber composition for the adhesive rubber layer. The state is also shown.

(Manufacture of friction transmission belt)
The laminated body of the reinforcing cloth that becomes the lower cloth and the sheet for the compressed rubber layer (unvulcanized rubber) is installed in a flat cogged mold in which the teeth and grooves are alternately arranged with the reinforcing cloth facing down, A cog pad (not completely vulcanized but in a semi-vulcanized state) with a cog part formed by press-pressing at 75 ° C. was produced. Next, both ends of the cog pad were cut vertically from the top of the cog crest.

Cover the inner die with teeth and grooves alternately on a cylindrical mold, engage the teeth and grooves, wrap the cog pad, joint at the top of the cog crest, and wind this cog pad After laminating a sheet for an adhesive rubber layer (lower adhesive rubber: unvulcanized rubber) on top, the core wire is spun into a spiral shape, and an adhesive rubber layer sheet (upper adhesive rubber: for the adhesive rubber layer) The same as the sheet), a stretched rubber layer sheet (unvulcanized rubber), and a reinforcing cloth as an upper cloth were wound in order to prepare a molded body. Thereafter, the jacket was put on and the mold was placed in a vulcanizing can and vulcanized at a temperature of 160 ° C. for 20 minutes to obtain a belt sleeve. This sleeve is cut with a cutter into a V-shaped cross-sectional shape with a predetermined width in the longitudinal direction of the belt, and a low-edge cogged V-belt (size) which is a transmission belt having a structure shown in FIG. : Upper width 22.0 mm, thickness 11.0 mm, outer peripheral length 800 mm).

A combination of the rubber composition for the adhesive rubber layer in the friction transmission belt (low-edge cogged V-belt) obtained in Examples and Comparative Examples and the rubber composition for the third treatment agent (overcoat layer) of the core wire It is shown in Table 7. Table 7 also shows the results of the belt durability running test.

From the result of the vulcanized rubber physical properties of the rubber composition for the adhesive rubber layer in Table 1, the rubber composition Z containing 20 parts by mass of silica with respect to the rubber composition Y containing 10 parts by mass of silica together with the content of silica. It can be seen that the amount of wear of the vulcanized rubber increases. Further, in the rubber compositions S and W in which the carbon black is reduced to 30 to 20 parts by mass with respect to the rubber composition Y containing 50 parts by mass of the carbon black, the wear amount increases as the carbon black content decreases. I understand that.

From the result of the peel test between the core wire subjected to the adhesion treatment in Table 5 and the rubber composition X for the adhesive rubber layer not containing silica, 40 mass of silica is added to the rubber composition for the third treatment agent (overcoat layer). In the rubber composition A containing part, the adhesive force between the adhesive rubber layer and the core wire was good, and the rubber layer was broken while the interface was bonded. On the other hand, in the rubber composition B containing no silica, peeling occurred completely at the interface between the adhesive rubber layer and the core wire. Further, in the rubber composition C in which silica was reduced to 10 parts by mass with respect to the rubber composition A, partial peeling occurred at the interface between the adhesive rubber layer and the core wire.

From the results (Table 7) of the durability running test of the friction transmission belt manufactured by combining the rubber composition for the adhesive rubber layer and the rubber composition for the third treatment agent (overcoat layer), it is compared with the adhesive rubber layer. Even if it is a friction transmission belt (Examples 1 to 3) containing a small amount of silica, when combined with an overcoat layer (coating) containing 40 parts by mass of silica, the core wire and the adhesive rubber even after running for 24 hours Adhesion with the layer was good and no peeling was observed. Furthermore, the amount of wear on the belt was small, and no wear on the pulley was observed. In particular, Example 2 is a friction transmission belt in which the ratio of silica in the adhesive rubber layer is as large as 33 parts by mass with respect to 100 parts by mass of carbon black. The amount of wear was slightly higher.

Example 4 is a friction transmission belt in which the amount of carbon black in the adhesive rubber layer is as large as 70 parts by mass. However, some peeling of the core wire was observed on the side of the belt after running for 24 hours, but this was a problem for practical use. It was not so much. Example 5 is a friction transmission belt in which the ratio of silica in the adhesive rubber layer is as small as 4 parts by mass with respect to 100 parts by mass of carbon black, but slight peeling of the core wire is seen on the side of the belt after running for 24 hours. However, there was no problem in practical use.

Example 6 is a friction transmission belt in which 10 parts by mass of silica is included in the overcoat layer, and some peeling of the core wire was observed on the side surface of the belt after running for 24 hours, but there was no problem in practical use. It was. Example 8 is a friction transmission belt in which 60 parts by mass of silica is included in the overcoat layer, but some peeling of the core wire was observed on the side of the belt after running for 24 hours, but there was no problem in practical use. there were. Considering the results of Examples 6 to 8, if the silica compounding amount of the overcoat layer is too small or too large, the core wire is peeled off.

Comparative Example 1 is a friction transmission belt in which 20 parts by mass of silica is contained in the adhesive rubber layer. However, the amount of wear of the belt during running for 24 hours was large, and further, wear of the pulley was also observed. Comparative Example 2 is a friction transmission belt that does not contain silica in either the adhesive rubber layer or the overcoat layer (coating), and the core wire was peeled off on the side of the belt after running for 24 hours (problem in practical use). ) Comparative Example 3 is a friction transmission belt that contains 10 parts by mass of silica in the adhesive rubber layer and no silica in the overcoat layer (coating), but the core wire peels off on the side of the belt after running for 24 hours. (Practical problem) Comparative Example 4 was a friction transmission belt having a carbon black amount of 20 mass parts in the adhesive rubber layer, but the amount of wear of the belt during 24-hour running was large.

Although the invention has been described in detail and with reference to specific embodiments, it will be apparent to those skilled in the art that various modifications and variations can be made without departing from the spirit and scope of the invention.
This application is based on Japanese Patent Application No. 2016-082465 filed on April 15, 2016 and Japanese Patent Application No. 2017-078980 filed on April 12, 2017, the contents of which are incorporated herein by reference.

The friction transmission belt of the present invention can be applied to, for example, a V belt (wrapped V belt, low edge V belt, low edge cogged V belt), V ribbed belt, flat belt, and the like. In particular, a V-belt (transmission belt) used in a transmission (continuously variable transmission) in which the gear ratio changes steplessly during belt travel, such as a motorcycle, an ATV (four-wheel buggy), a snowmobile, etc. The present invention is preferably applied to a low edge cogged V belt and a low edge double cogged V belt used in a transmission.

DESCRIPTION OF SYMBOLS 1 ... Friction

power transmission belt

2, 6 ... Reinforcement cloth 3 ... Stretch rubber layer 4 ... Adhesive rubber layer 4a ... Core body 5 ... Compression rubber layer

Claims

A friction transmission belt comprising an adhesive rubber layer in contact with at least a part of a core extending in a longitudinal direction of the belt,
The adhesive rubber layer is formed of a first vulcanized rubber composition containing a rubber component and a filler,
The filler contains 30 parts by mass or more of carbon black and 0.1 to 15 parts by mass of silica with respect to 100 parts by mass of the rubber component, and the core is a second vulcanized rubber containing the rubber component and silica. A friction transmission belt having an overcoat layer formed of a composition on its surface.
The friction transmission belt according to claim 1, wherein the proportion of carbon black in the first vulcanized rubber composition is 30 to 60 parts by mass with respect to 100 parts by mass of the rubber component.
The friction transmission belt according to claim 1 or 2, wherein the silica content of the first vulcanized rubber composition is 10 to 30 parts by mass with respect to 100 parts by mass of carbon black.
The friction transmission belt according to any one of claims 1 to 3, wherein the silica ratio of the second vulcanized rubber composition is 10 parts by mass or more with respect to 100 parts by mass of the rubber component.
The friction transmission belt according to claim 4, wherein the ratio of silica in the second vulcanized rubber composition is 15 to 50 parts by mass with respect to 100 parts by mass of the rubber component.
The friction transmission belt according to any one of claims 1 to 5, wherein the average thickness of the overcoat layer is 5 to 30 µm.
The friction transmission belt according to any one of claims 1 to 6, wherein the rubber component of the first vulcanized rubber composition is chloroprene rubber.
The friction transmission belt according to any one of claims 1 to 7, wherein the rubber component of the second vulcanized rubber composition is chloroprene rubber.
The friction transmission belt according to any one of claims 1 to 8, wherein the core includes a twisted cord including a polyester fiber and / or a polyamide fiber.