JP4861029B2 - Friction transmission belt - Google Patents

Description

  The present invention relates to a friction transmission belt used for power transmission.

  In recent years, there has been a demand for higher performance and higher performance of automotive parts, especially automobile parts. Under such circumstances, there is a demand for a power transmission belt that has a high transmission performance not only during normal travel but also when wet. In addition, there is a strict requirement for quietness. In particular, in the driving device, since sounds other than the engine sound are abnormal sounds, there is also a strict requirement for measures against belt sound generation.

  Abnormal noise in the friction transmission belt includes slip noise generated under conditions of large rotational fluctuations and high load conditions, and noise generated by the adhesive rubber adhering to the groove bottom between the ribs as a result of the adhesive rubber layer causing adhesive wear. There is. Further, it is known that when the water enters the engine room during rainy weather and the like and water adheres between the belt and the pulley, an abnormal noise due to slip occurs. In particular, friction transmission belts made of ethylene / α-olefin rubber, which has been attracting attention in recent years, are inferior in water wettability compared to chloroprene rubber, which is used for general purposes. The decrease in noise and the occurrence of abnormal noise were noticeable.

As a measure against sound generation during such flooding, at least each rib portion of the V-ribbed belt has an elastic modulus intermediate between the elastic modulus of the cotton short fiber and the main rubber constituting each rib portion and the elastic modulus of the cotton short fiber. Attempts have been made to reduce abnormal noise generated by water injection such as rain by containing the short nylon fibers. According to the above configuration, each rib portion of the V-ribbed belt contains cotton short fibers. Therefore, when the coefficient of friction reduced during water injection is recovered, the cotton short fibers absorb water to dry the wet state. The friction coefficient changes smoothly with the transition to the state. In addition to the short cotton fibers, each rib portion contains intermediate short fibers having an elastic modulus between the short cotton fibers and the main rubber of the rib portions. Each rib portion includes the main rubber. In other words, since it has three or more types of friction coefficients, it is possible to suppress a sudden stick-slip phenomenon and prevent the occurrence of abnormal noise by preventing the repeated sliding and close contact. (For example, see Patent Document 1)
JP 2003-202055 A

  However, in the case of the V-ribbed belt, as the running progresses, the short fibers fall off or the tip wears out, so that although the sound suppression effect is high in the initial stage, it is difficult to maintain the effect in the long term. It was. Also, in order to achieve a high sound suppression effect, it is necessary to increase the amount of short fibers, but problems such as poor dispersion of short fibers and a decrease in workability and adhesiveness of rubber sheets have been discovered as adverse effects. . Specifically, there have been inconveniences such as tearing or perforation of rubber sheets in the rolling process, or difficulty in producing a laminate due to poor adhesion between rubber sheets. Above all, this tendency was remarkable because of the poor dispersion of the short cotton fibers.

  As a result of intensive studies in view of the above problems, the present invention is proposed, and the object is to have high sound resistance during running without adversely affecting workability, especially when wet. It is an object of the present invention to provide a friction transmission belt that suppresses the deterioration of transmission performance and abnormal noise for a long period of time, and is further excellent in wear resistance and durability.

That is, the invention described in claim 1 is a friction transmission belt, wherein at least a surface layer of the friction transmission portion is composed of a porous rubber composition having a bubble rate of 5 to 20%, and the surface of the surface layer forms irregularities. It is characterized by that.

  Invention of Claim 2 of this application is a friction transmission belt of Claim 1, Comprising: A porous rubber composition contains in the ratio of 50-150 weight part of reinforcing fillers with respect to 100 weight part of rubber | gum. It is characterized by.

  The invention according to claim 3 of the present application is the friction transmission belt according to claim 2, wherein the reinforcing filler is carbon black.

The invention of claim 4, wherein is a friction transmission belt according to claim 3, carbon black, the nitrogen adsorption specific surface area of 40~120m ² / g, a dibutyl phthalate oil absorption of 80~130cm ³ / 100g carbon It is characterized by being black.

  The invention according to claim 5 of the present application is the friction transmission belt according to any one of claims 1 to 4, wherein the porous rubber composition contains a lubricant.

  The invention according to claim 6 of the present application is the friction transmission belt according to claim 5, wherein the lubricant is contained in a ratio of 10 to 50 parts by weight with respect to 100 parts by weight of the rubber.

  The invention according to claim 7 of the present application is the friction transmission belt according to claim 5 or 6, wherein the lubricant is a solid lubricant.

  The invention described in claim 8 is the friction transmission belt according to claim 7, wherein the solid lubricant is graphite and / or ultrahigh molecular weight polyethylene.

  The invention according to claim 9 of the present application is the friction transmission belt according to any one of claims 1 to 8, wherein the rubber is mainly composed of an ethylene / α-olefin elastomer.

  The invention according to claim 10 of the present application is the friction transmission belt according to any one of claims 1 to 9, wherein the friction transmission belt is a V-ribbed belt provided with a rib portion extending in the belt longitudinal direction. It is characterized by.

  The invention according to claim 11 of the present application is the friction transmission belt according to claim 10, characterized in that at least a part of the surface of the rib portion is made of a porous rubber composition.

  The invention according to claim 12 of the present application is the friction transmission belt according to claim 10 or 11, wherein at least a part of the back surface of the belt is made of a porous rubber composition.

In the invention according to claim 1 of the present application, at least the surface layer of the friction transmission portion is composed of a porous rubber composition having a cell ratio of 5 to 20%, and the surface of the surface layer forms irregularities, so It is possible to provide a friction transmission belt that has high sound resistance, suppresses deterioration of transmission performance and generation of abnormal noise particularly when wet, and has excellent durability.

  In the invention according to claim 2, the porous rubber composition contains 50 to 150 parts by weight of the reinforcing filler with respect to 100 parts by weight of the rubber, so that the sound resistance is higher and the wear resistance is higher. Thus, a friction transmission belt having excellent durability can be obtained.

  In the invention according to claim 3 of the present application, the reinforcing property can be further enhanced because the reinforcing filler is carbon black.

The invention of claim 4, wherein the carbon black, the nitrogen adsorption specific surface area of 40~120m ² / g, by dibutyl phthalate oil absorption of carbon black of 80~130cm ³ / 100g, to further increase the reinforcing property Can do.

  In the invention according to claim 5 of the present application, the porous rubber composition can further improve the sound-proofing property during running by containing a lubricant.

  The invention according to claim 6 of the present application can provide a friction transmission belt excellent in sound resistance and durability by containing the lubricant in a ratio of 10 to 50 parts by weight with respect to 100 parts by weight of rubber. .

  In the seventh aspect of the present invention, since the lubricant is a solid lubricant, the effect can be maintained over a long period of time, and an appropriate friction coefficient can be maintained.

  In the invention according to claim 8, the solid lubricant is graphite and / or ultrahigh molecular weight polyethylene, so that the friction transmission belt can be further improved in sound resistance and durability.

  The invention according to claim 9 of the present application has excellent heat resistance, cold resistance and ozone resistance while making the water wettability good because the rubber is mainly composed of an ethylene / α-olefin elastomer. A friction transmission belt satisfying dehalogenation can be obtained. That is, when an ethylene / α-olefin elastomer is used, there is a tendency that a decrease in performance when wet is noticeable due to the poor wettability of the rubber itself. However, according to the configuration of the present invention, even when the main component of the rubber is ethylene / α-olefin, it is possible to realize improvement in transmission performance and suppression of sound generation under water, and ethylene / α-olefin elastomer. It is possible to have excellent properties.

  The invention according to claim 10 of the present application is a V-ribbed belt in which the friction transmission belt is provided with a rib portion extending in the longitudinal direction of the belt and has low noise during traveling, particularly power transmission performance and sound resistance when wet. A highly durable V-ribbed belt with improved properties and the like can be obtained.

  In the invention according to claim 11 of the present application, at least a part of the surface of the rib portion is made of the porous rubber composition, so that an effect can be obtained in driving the rib surface.

  In the invention according to claim 12 of the present application, at least a part of the back surface of the belt is made of a porous rubber composition, and therefore, an effect can be obtained in driving the back surface.

  Embodiments of the present invention will be described. In the present embodiment, the present invention is applied to a V-ribbed belt having a rib portion extending in the longitudinal direction of the belt as a friction transmission belt.

  As shown in FIG. 1, the V-ribbed belt 1 includes a stretch layer 5 that forms a back surface 8, an adhesive layer 2 that is disposed below the stretch layer 5, and a compression layer 4 that is disposed below the stretch layer 5. It is configured. Further, the core wire 3 is disposed so as to be embedded in the main body along the longitudinal direction of the belt, and the core wire 3 is embedded in a state where a part thereof is in contact with the stretch layer 5 and the remaining part is in contact with the adhesive layer 2. ing. The compressed layer 4 is provided with a plurality of rib portions 7 having a substantially trapezoidal cross section and extending in the belt longitudinal direction. Moreover, the short fibers contained in the compressed layer 4 exhibit a flow state along the rib shape, and the short fibers near the surface are oriented along the rib shape. On the other hand, the short fibers contained in the stretch layer 5 are oriented in the belt width direction.

Here, the friction transmission surface refers to the surface of the friction transmission portion, that is, the surface of the rib portion 7 (the surface of the compression layer 4). Point to. That is, in the present invention, at least a part of the friction transmission surface is constituted by a specific rubber composition. Specifically, when the friction transmission belt is a V-ribbed belt that performs back-side driving, at least the rib portion surface and The back of the belt is made of a porous rubber composition having a cell rate of 5 to 20%, and the rib surface and / or the back of the belt form irregularities .

  Specifically, in the friction transmission belt (V-ribbed belt 1), all of the friction transmission portions (compression layer 4 and / or stretch layer 5) can be made of a porous rubber composition. Only the surface layer of the portion (compressed layer 4 and / or stretched layer 5) can be composed of a porous rubber composition. In consideration of the physical properties of the friction transmission part, it is preferable that only the surface layer is composed of a porous rubber composition. In this case (when only the surface layer is composed of the porous rubber composition), the thickness of the surface layer is desirably equal to or greater than the thickness that is damaged by wear or the like until the belt life, specifically 0.5 to 1. It is preferably 0 mm.

Here, the bubble ratio is the density ρm of the rubber part other than the bubbles and the density ρs of the entire rubber composition.
Bubble ratio = (ρm / ρs−1) × 100 (%)
The amount represented by The cell structure is not limited to closed cells or open cells, and both may coexist. In the present invention, by forming at least a part of the friction transmission surface with a porous rubber composition having a cell ratio of 5 to 20%, it is possible to form irregularities with a water film removing effect on the surface, In this case, the friction transmission belt can suppress abnormal noise. If the bubble rate is less than 5%, the effect of removing the water film is extremely small, and the effect of suppressing the deterioration of transmission performance and the generation of abnormal noise during water exposure is not significant. There is a problem that the strength of the friction transmission surface is rapidly reduced.

  The raw rubber composing the compression layer 4 includes natural rubber, butyl rubber, styrene / butadiene rubber, chloroprene rubber, alkylated chlorosulfonated polyethylene, ethylene / α-olefin rubber, hydrogenated nitrile rubber, hydrogenated nitrile rubber and the like. A rubber material such as a mixed polymer with a saturated carboxylic acid metal salt may be used alone or in combination. Among these, ethylene / α-olefin rubber is preferable because it has excellent ozone resistance, heat resistance, and cold resistance, is relatively inexpensive, and satisfies the requirement of dehalogenation.・ It is desirable to use α-olefin rubber. In addition, ethylene / α-olefin rubber is poor in water wettability compared to other rubbers, and therefore, the application of the present invention significantly improves power transmission and noise reduction during water injection. In addition, the rubber | gum used as a main component refers to the rubber | gum of the component most contained in the composition of rubber | gum in the case where multiple types of rubber materials are contained, for example, 50% If it is contained above, it becomes the main component.

  The ethylene / α-olefin rubber is a copolymer of ethylene and α-olefin (propylene, butene, hexene, octene, etc.) or a copolymer of ethylene, the α-olefin and the non-conjugated diene, specifically Refers to rubbers such as ethylene-propylene rubber (EPM) and ethylene-propylene-diene copolymer (EPDM). Examples of the diene component include non-conjugated dienes having 5 to 15 carbon atoms such as ethylidene norbornene, dicyclopentadiene, 1,4-hexadiene, cyclooctadiene, and methylene norbornene. EPDM has the property of being excellent in heat resistance and cold resistance, and a power transmission belt having high heat resistance and cold resistance performance can be obtained. This EPDM preferably has an iodine value of 3 to 40. If the iodine value is less than 3, vulcanization of the rubber composition is not sufficient and problems of wear and adhesion occur, and if the iodine value exceeds 40, the scorch of the rubber composition becomes short and difficult to handle, Heat resistance deteriorates.

  For crosslinking the rubber, sulfur or organic peroxide is used. Specific examples of the organic peroxide include di-t-butyl peroxide, dicumyl peroxide, t-butylcumyl peroxide, 1.1-t-butylperoxy-3.3.5-trimethylcyclohexane, and 2. 5-di-methyl-2.5-di (t-butylperoxy) hexane, 2.5-di-methyl-2.5-di (t-butylperoxy) hexane-3, bis (t-butylperoxydi-isopropyl) benzene, Examples include 2.5-di-methyl-2.5-di (benzoylperoxy) hexane, t-butylperoxybenzoate, and t-butylperoxy-2-ethyl-hexyl carbonate. This organic peroxide is preferably used alone or as a mixture in the range of 1 to 8 parts by weight with respect to 100 parts by weight of rubber.

  Moreover, you may mix | blend a vulcanization accelerator. Examples of vulcanization accelerators include thiazole, thiuram, and sulfenamide vulcanization accelerators. Specific examples of thiazole vulcanization accelerators include 2-mercaptobenzothiazole, 2-mercaptothiazoline, dibendiazyl, Disulfide, zinc salt of 2-mercaptobenzothiazole, etc., and thiuram-based vulcanization accelerators include tetramethylthiuram monosulfide, tetramethylthiuram disulfide, tetraethylthiuram disulfide, N, N′-dimethyl. -N, N'-diphenylthiuram disulfide and the like, and as the sulfenamide vulcanization accelerator, specifically, N-cyclohexyl-2-benzothiazylsulfenamide, N, N'-cyclohexyl-2 -Benzothiazylsulfenamide and the like. As other vulcanization accelerators, bismaleimide, ethylenethiourea, and the like can be used. These vulcanization accelerators may be used alone or in combination of two or more.

  Further, by blending a co-agent, it is possible to increase the degree of crosslinking and prevent problems such as adhesive wear. Examples of co-crosslinking agents include TAIC, TAC, 1,2 polybutadiene, metal salts of unsaturated carboxylic acids, p-benzoquinone dioxime, p, p'-dibenzoquinone dioxime, tetrachlorobenzoquinone poly (P- Dinitrobenzoquinone), guanidine, trimethylolpropane trimethacrylate, ethylene glycol dimethacrylate, NN′-m-phenylenebismaleimide, sulfur, etc., which are usually used for organic peroxide crosslinking, among which N, N ′ -M-Phenylenedimaleimide and / or quinonedioximes are preferred. The blending amount is desirably 0.5 to 10 parts by weight with respect to 100 parts by weight of rubber. If the amount is less than 0.5 parts by weight, the effect of addition is not remarkable, and if it exceeds 10 parts by weight, the tearing force and adhesive strength are reduced. There is a problem such as. At this time, when N, N′-m-phenylene dimaleimide is selected as the co-crosslinking agent, the cross-linking density is high, the wear resistance is high, and the difference in transmission performance between water injection and drying is small. is there. Further, when quinone dioximes are selected, there is a feature that the adhesiveness with the fiber base material is excellent.

  In addition, in this embodiment, since the rubber composition which comprises the compression layer 4 turns into a rubber composition which comprises a friction transmission surface, the porosity comprised so that the compression layer 4 might become 5 to 20% of a bubble rate. It is composed of a rubber composition. Examples of the porous rubber composition include a foamed rubber composition obtained by foaming and crosslinking a rubber composition containing a foaming agent. Examples of the foaming agent include inorganic foaming agents such as ammonium bicarbonate and sodium bicarbonate, N, N′-dinitrosopentamethylenetetramine, 4,4′-oxybis (benzenesulfonylhydrazide), hydrazodicarbonamide, and barium azo. Organic foaming agents such as dicarboxylate and azodicarbonamide can be used without particular limitation. It is also possible to mix a foaming auxiliary agent, for example, urea can be used. Among the above foaming agents, the combination of azodicarbonamide and urea is particularly preferable from the viewpoints of safety, easy control of the amount of decomposition gas and decomposition temperature, and the like.

  And the porous rubber composition increases the storage elastic modulus of the rubber part other than bubbles (other than bubbles and short fibers when short fibers are contained), thereby increasing the sound resistance and wear resistance of the friction transmission belt. It becomes possible to improve the property. Specifically, it is desirable to prepare the storage elastic modulus of the rubber part other than the bubbles to be 40 to 100 MPa. If the storage elastic modulus is less than 40 MPa, the deformation of the compression layer increases when wound around the pulley, and the contact area increases rapidly, thereby increasing the adhesion between the rubber surface and the pulley surface. This behavior may increase the coefficient of friction and easily generate abnormal noise. Furthermore, other physical properties, particularly wear resistance, may deteriorate. On the other hand, if the storage elastic modulus exceeds 100 MPa, cracks are likely to occur during running, and the belt life may be shortened. The storage elastic modulus is a value measured by dynamic viscoelasticity measurement, and is performed under the conditions of dynamic strain 0.05%, frequency 10 Hz, and temperature 100 ° C.

As a specific configuration for increasing the storage elastic modulus of the rubber part other than air bubbles (air bubbles and short fibers), the reinforcing filler is 50 to 150 parts by weight, more preferably 100 to 150 parts by weight, with respect to 100 parts by weight of the rubber. A porous rubber composition contained in a proportion of parts can be used. If the reinforcing filler is less than 50 parts by weight, the sound resistance and wear resistance are not sufficient, and if it exceeds 150 parts by weight, the crack resistance may be lowered. Examples of the reinforcing filler include carbon black and silica, but it is desirable to select carbon black in order to enhance the reinforcing property. The carbon black is not limited, in consideration of the reinforcement, the nitrogen adsorption specific surface area 40~120cm ² / g, a dibutyl phthalate oil absorption is possible to use those having characteristics of 80~130cm ³ / 100g preferable. Here, the nitrogen adsorption specific surface area (N ₂ SA) is a specific surface area of carbon black, and is measured according to JIS K 6217-2. The dibutyl phthalate oil absorption (DBP oil absorption) is a structure index and is measured according to JIS K 6217-4.

  In addition, the friction transmission surface composed of the porous rubber composition has a smaller pulley contact area than usual due to the presence of air bubbles. However, the addition of a lubricant further reduces the friction coefficient of the friction transmission surface. Therefore, it is possible to improve pronunciation resistance. As the lubricant, either a liquid lubricant or a solid lubricant can be used. However, since the liquid lubricant has an extremely low friction coefficient, there is a possibility that the transmission efficiency may be lowered. Since it is difficult to achieve a long-term friction reduction effect by dissipating, it is desirable to use a solid lubricant capable of lowering the friction coefficient over a long period of time. As the solid lubricant, graphite, molybdenum disulfide, mica, talc, antimony trioxide, molybdenum diselenide, tungsten disulfide, polytetrafluoroethylene (PTFE), ultrahigh molecular weight polyethylene, etc. are used alone or in combination. be able to. Of these, graphite and / or ultrahigh molecular weight polyethylene are preferred.

  The lubricant is desirably contained in an amount of 10 to 50 parts by weight with respect to 100 parts by weight of rubber. If the amount is less than 10 parts by weight, the effect of reducing the friction coefficient is poor. If the amount exceeds 50 parts by weight, the durability may be lowered, and foaming may not be sufficiently performed, so that a desired bubble ratio may not be obtained.

  The porous rubber composition can contain short fibers. Examples of the short fibers include short fibers made of polyamide, polyester, cotton, aramid, polyparaphenylene benzobisoxazole, and the like. The aramid fiber has an aromatic ring in the molecular structure, and examples thereof include trade names Conex, Nomex, Kevlar, Technora and Twaron. The short fibers preferably have a fiber length of 1 to 20 mm, and the amount added is, for example, 5 to 50 parts by weight with respect to 100 parts by weight of rubber. The short fibers can be subjected to an adhesion treatment as necessary.

  In addition to the above, those used for ordinary rubber compounds such as fillers, plasticizers, stabilizers, processing aids, and colorants can be used as necessary.

  The adhesive layer 2 and the stretch layer 5 can be made of the same rubber composition as that of the compression layer 4, but may be composed of another rubber composition. For example, the adhesive layer 2 is not particularly required to be foamed, and it is preferable that short fibers are not mixed in consideration of adhesiveness.

  Core wire 3 is polyethylene terephthalate (PET) fiber, polyethylene naphthalate (PEN) fiber, polytrimethylene terephthalate (PTT) fiber, polybutylene terephthalate (PBT) fiber, polyparaphenylene benzobisoxazole (PBO) fiber, polyamide fiber , Twisted cords composed of glass fiber, carbon fiber, aramid fiber, and the like can be used.

  It is desirable that the core wire is subjected to an adhesive treatment. For example, (1) a pre-dip is made by impregnating a tank containing a treatment liquid containing a compounding agent selected from an epoxy compound and an isocyanate compound with an untreated cord. Then, (2) drying is performed by passing through a drying oven set at 160 to 200 ° C. for 30 to 600 seconds, (3) followed by immersion in a tank containing an adhesive solution made of RFL liquid, and (4) 210 The film is stretched by −1 to 3% for 30 to 600 seconds through a stretching heat setting processor set at a temperature of ˜260 ° C. to obtain a stretching treatment cord.

  Examples of the isocyanate compound used in this pretreatment liquid include 4,4′-diphenylmethane diisocyanate, tolylene 2,4-diisocyanate, polymethylene polyphenyl diisocyanate, hexamethylene diisocyanate, and polyaryl polyisocyanate (for example, PAPI as a trade name) ) Etc. This isocyanate compound is used by mixing with an organic solvent such as toluene or methyl ethyl ketone.

  In addition, blocked polyisocyanates in which the isocyanate group of the polyisocyanate is blocked by reacting the isocyanate compound with a blocking agent such as phenols, tertiary alcohols, and secondary alcohols can also be used.

  Examples of the epoxy compound include reaction products of polyhydric alcohols such as ethylene glycol, glycerin and pentaerythritol, polyalkylene glycols such as polyethylene glycol and halogen-containing epoxy compounds such as epichlorohydrin, resorcin, bis (4-hydroxy Phenyl) dimethylmethane, phenol-formaldehyde resin, resorcinol-formaldehyde resin and other polyhydric phenols and reaction products with halogen-containing epoxy compounds. The epoxy compound is used by mixing with an organic solvent such as toluene or methyl ethyl ketone.

  The RFL treatment liquid is a mixture of resorcin and formaldehyde precondensate with rubber latex. In this case, the molar ratio of resorcin and formaldehyde is preferably 1: 2 to 2: 1 in order to increase the adhesive force. . If the molar ratio is less than 1/2, the three-dimensional reaction of resorcin-formaldehyde resin proceeds too much and gels, while if it exceeds 2/1, the reaction between resorcin and formaldehyde does not progress so much, resulting in a decrease in adhesive strength. To do.

  Examples of rubber latex include styrene / butadiene / vinylpyridine terpolymers, hydrogenated nitrile rubber, chloroprene rubber, and nitrile rubber.

  Further, the solid content mass ratio of the initial condensate of resorcin / formaldehyde and the rubber latex is preferably 1: 2 to 1: 8, and if this range is maintained, it is suitable for increasing the adhesive force. When the above ratio is less than 1/2, the resin content of resorcin-formaldehyde increases, the RFL film becomes hard and the dynamic adhesion becomes worse, and when it exceeds 1/8, the resin content of resorcin-formaldehyde. Therefore, the RFL film becomes soft and the adhesive strength decreases.

  Further, a vulcanization accelerator or a vulcanizing agent may be added to the RFL liquid, and the vulcanization accelerator to be added is a sulfur-containing vulcanization accelerator. Specifically, 2-mercaptobenzothiazole (M ) And salts thereof (for example, zinc salts, sodium salts, cyclohexylamine salts, etc.) thiazoles such as dibenzothiazyl disulfide (DM), sulfenamides such as N-cyclohexyl-2-benzothiazylsulfenamide (CZ) , Thiurams such as tetramethylthiuram monosulfide (TS), tetramethylthiuram disulfide (TT), dipentamethylenethiuram tetrasulfide (TRA), sodium di-n-butyldithiocarbamate (TP), zinc dimethyldithiocarbamate ( PZ) Dithiocarbamine such as zinc diethyldimethyldithiocarbamate (EZ) There are salts and the like.

  Examples of the vulcanizing agent include sulfur, metal oxides (zinc oxide, magnesium oxide, lead oxide), organic peroxides, and the like, which are used in combination with the above vulcanization accelerator.

  The V-ribbed belt is not limited to the configuration shown in FIG. 1, and for example, a V-ribbed belt in which no adhesive layer is disposed and a V-ribbed belt in which an extension layer serving as a back surface is formed of canvas belong to the technical scope of the present invention. Hereinafter, these embodiments will be described with reference to the drawings.

  The V-ribbed belt 21 shown in FIG. 2 has a configuration in which a stretched layer 25 whose back surface 28 is made of canvas, an adhesive layer 22 is disposed below the stretched layer 25, and a compressed layer 24 is disposed below the stretched layer 25. . The core wire 23 is embedded in the main body along the belt longitudinal direction, and is embedded in the adhesive layer 22. The compressed layer 24 is provided with a plurality of rib portions 27 having a substantially triangular cross section extending in the belt longitudinal direction. Here, the short fibers contained in the compressed layer 24 are oriented in the belt width direction.

  The canvas constituting the stretch layer 25 is a fiber base selected from woven fabric, knitted fabric, non-woven fabric and the like. Known and publicly used fiber materials can be used. For example, natural fibers such as cotton and hemp, inorganic fibers such as metal fibers and glass fibers, and polyamide, polyester, polyethylene, polyurethane, polystyrene, and polyfluoroethylene. , Organic fibers such as polyacryl, polyvinyl alcohol, wholly aromatic polyester, and aramid. In the case of a woven fabric, these yarns are woven by plain weaving, twill weaving, satin weaving or the like.

  The canvas is preferably immersed in the RFL liquid according to a known technique. In addition, after immersion in the RFL solution, friction can be performed by rubbing unvulcanized rubber into the canvas, or immersion can be performed in a soaking solution in which the rubber is dissolved in a solvent. The RFL solution may be appropriately mixed with a carbon black solution to blacken the treatment, or a known surfactant may be added in an amount of 0.1 to 5.0% by mass.

  The V-ribbed belt 31 shown in FIG. 3 has a configuration in which a stretch layer 35 forming a back surface 38 and a compression layer 34 are disposed below the stretch layer 35. The core wire 33 is embedded in the main body along the longitudinal direction of the belt, and a part thereof is in contact with the stretch layer 35 and the remaining part is in contact with the compression layer 34. The compression layer 34 is provided with a plurality of rib portions 37 having a substantially triangular cross section extending in the belt longitudinal direction, and a flocking layer is provided on the rib surface. Here, the short fibers contained in the stretched layer 25 are oriented in a random direction.

  FIGS. 1 and 3 show a configuration in which the stretch layers 5 and 35 are not made of a canvas but are made of a rubber composition containing short fibers. An uneven pattern can be provided on the surface. Examples of the concavo-convex pattern include a knitted fabric pattern, a woven fabric pattern, a suede woven fabric pattern, and the like, and most preferably a woven fabric pattern.

  In FIG. 3, the short fibers contained in the stretched layer 35 are oriented in the random direction, but they may be oriented in one direction such as in the belt width direction as shown in FIG. In addition, when oriented in a random direction, there is a feature that the generation of cracks and cracks from multiple directions can be suppressed. At this time, if a short fiber (for example, a milled fiber) having a bent portion is selected as the short fiber, more It has a feature that it can withstand the force acting from the direction.

  In the case where the adhesive layer is not disposed as shown in FIG. 3, the core wire 33 is embedded in the belt body at the boundary region between the stretch layer 35 and the compression layer 34. At this time, considering the adhesiveness between the core wire 33 and the belt body, it is desirable that one of the stretched layer 35 and the compressed layer 34 is made of a rubber composition containing no short fibers.

  In addition, in FIG. 3, although the compression layer 24 is set as the structure which provided the flocked layer on the rubber composition surface which does not contain a short fiber, it shall be set as the structure which provided the flocked layer on the rubber composition surface containing a short fiber. Is also possible. In FIG. 1, the short fibers contained in the compressed layer 24 are in a flow state along the rib shape. However, the short fibers may be oriented in the width direction as shown in FIG.

  When the V-ribbed belt performs back surface transmission, the surface of the stretch layer can also be a friction transmission surface. Therefore, the stretch layer may be composed of the rubber composition of the present invention. For example, in the case of FIGS. 1 and 3, since both the back surface and the rib portion surface are formed of a rubber composition, at least one of them may be formed of the rubber composition of the present invention. In the case of FIG. 2, since the back surface is formed of canvas, at least the rib part surface may be formed of the rubber composition of the present invention.

  Next, a method for manufacturing these V-ribbed belts will be described. Although it does not limit as a manufacturing method, For example, there exist the following methods.

  As a first method, first, a member constituting an extension layer and an adhesive rubber sheet constituting an adhesive layer are wound around a peripheral surface of a cylindrical molding drum, and then a cord made of a cord is spirally wound thereon. Then, a compressed rubber sheet constituting the compression layer is wound in order to form an unvulcanized sleeve, and then vulcanized to obtain a vulcanized sleeve. Next, the vulcanization sleeve is hung on a driving roll and a driven roll and travels under a predetermined tension, and the rotated grinding wheel is moved so as to abut on the traveling vulcanization sleeve to compress the sleeve. A surface of 3 to 100 grooves is polished on the surface at a time to form a friction transmission surface. The sleeve thus obtained is removed from the driving roll and the driven roll, the sleeve is hung on the other driving roll and the driven roll, traveled, cut into a predetermined width by a cutter, and finished into individual V-ribbed belts. .

  As a second method, after winding a compression rubber sheet constituting a compression layer and an adhesive rubber sheet constituting an adhesive layer around a cylindrical molding drum having rib markings on the peripheral surface, the core wire is spun, An unvulcanized sleeve is arranged by winding a member constituting the stretch layer. Thereafter, the unvulcanized sleeve is vulcanized while being pressed against the molding drum, whereby a rib is formed on the compression layer. The obtained vulcanized sleeve is formed with ribs. The rib surface is polished if necessary, and cut into a predetermined width to obtain individual V-ribbed belts.

  As a third method, after winding a member constituting an extension layer and an adhesive rubber sheet constituting an adhesive layer on a flexible jacket mounted on a cylindrical molding drum, spinning a core wire thereon Further, the compressed rubber sheets constituting the compression layer are sequentially wound endlessly to form an unvulcanized sleeve. Then, the flexible jacket is expanded, and the unvulcanized sleeve is pressed against an outer mold having an inscription corresponding to the rib portion, and vulcanized. The obtained vulcanized sleeve is formed with ribs. The rib surface is polished if necessary, and cut into a predetermined width to obtain individual V-ribbed belts.

  As a fourth method, after forming a first unvulcanized sleeve in which a compressed rubber sheet constituting a compression layer is disposed on a flexible jacket mounted on a cylindrical molding drum, the flexible jacket is The first unvulcanized sleeve is expanded and pressed against an outer mold having an inscription corresponding to the rib portion to produce a preform having the rib portion. Then, the inner mold is separated from the outer mold to which the preformed body is adhered, and then the member constituting the stretch layer and the adhesive rubber sheet constituting the adhesive layer are arranged on the inner mold, and the core wire is spun. A second unvulcanized sleeve is formed. Then, the flexible jacket is expanded, and the second unvulcanized sleeve is pressed from the inner peripheral side to the outer mold to which the preform is in close contact, and is vulcanized integrally with the preform. Ribs are formed on the obtained vulcanized belt sleeve, but the rib surface is polished if necessary and cut into a predetermined width to obtain individual V-ribbed belts.

  When the compression layer of the V-ribbed belt is composed of two layers, a surface layer and an inner layer, a compression rubber sheet having a two-layer structure of the surface layer and the inner layer is wound, or the surface compression rubber sheet and the inner layer compression rubber sheet are sequentially wound. It is necessary to form an unvulcanized sleeve in which a compressed layer having a two-layer structure of a surface layer and an inner layer is disposed by winding or the like. At this time, since the rib is formed by polishing in the first method, it is considered that the surface layer exists on the rib crest of the obtained V-ribbed belt, but the inner layer is exposed on the rib side surface and the rib bottom. Therefore, it is desirable that the V-ribbed belt composed of two layers of the surface layer and the inner layer is manufactured by the second method, the third method, or the fourth method.

  Further, the V-ribbed belt having no adhesive layer as shown in FIG. 3 can be obtained by manufacturing the above method without arranging an adhesive rubber sheet. Further, as shown in FIG. 1, the V-ribbed belt in which the short fibers contained in the compressed layer 4 exhibit a flow state along the rib shape is manufactured by, for example, the second method, the third method, or the fourth method. It is obtained by doing. And the V-ribbed belt in which the short fibers contained in the compressed layer 24 are oriented in the width direction as shown in FIG. 2 can be obtained by, for example, the first method.

  Here, the rubber composition constituting each layer can be prepared as follows. Specifically, each compounding agent and rubber are kneaded using a kneader such as a Banbury mixer or a kneader. And the rubber sheet which comprises each layer can be produced by rolling the rubber composition prepared in this way.

  The present embodiment is an example in which the present invention is applied to a V-ribbed belt. However, the present invention is not limited to a V-ribbed belt, and the present invention can be applied to other types of friction transmission belts, for example, a V-belt.

  Hereinafter, a description will be given with specific examples.

Examples 1-7, Comparative Examples 1-3
A rubber composition was prepared according to the formulation shown in Table 1, kneaded with a Banbury mixer, and then rolled with a calender roll to prepare a 2.2 mm thick unvulcanized rubber sheet. Here, as an evaluation of workability, the rubber sheet after rolling was visually observed to confirm the sheeting state. ○ indicates a state in which the rubber sheet is not torn or perforated, Δ indicates a state in which the rubber sheet is torn or perforated, and × indicates a state in which sheeting is impossible. Further, the bubble ratio was calculated according to the above-described formula. Further, an unvulcanized rubber sheet was prepared from the rubber composition prepared by removing the short fibers from the composition shown in Table 1, and vulcanized at 165 ° C for 30 minutes under the condition of a foaming rate of 0%. The storage elastic modulus of rubber was measured under the conditions of dynamic strain 0.05%, frequency 10 Hz, and temperature 100 ° C. according to JIS K6394.

  Next, a V-ribbed belt was produced. In the V-ribbed belts of Examples 1 to 3 and Comparative Examples 1 and 2, a cord made of a polyester fiber rope is embedded in the belt body, and the back surface (stretch layer) is formed of a two-ply rubberized cotton canvas. In the compression layer provided on the surface side, three rib portions are arranged in the longitudinal direction of the belt. The compressed layer contains short fibers, and the short fibers are oriented in the belt width direction.

  Here, the compression layer was formed using an unvulcanized rubber sheet made of a rubber composition prepared according to the formulation shown in Table 1. As a belt manufacturing method, the following known methods were used. First, a two-ply cotton canvas with rubber and an adhesive rubber sheet are sequentially wound around a flat cylindrical molding mold, the core wire is spun, and further, the compressed rubber sheet is wound on the compressed rubber sheet. Insert the vulcanization jacket. Next, after the molding mold is placed in a vulcanizing can and vulcanized, the cylindrical vulcanizing sleeve is taken out from the molding mold. Then, the compressed layer of the vulcanized sleeve was ground with a grinder to form a plurality of rib portions, and then cut into individual belts with a cutter to obtain a V-ribbed belt. Then, using this V-ribbed belt, a heat-resistant running test was performed as a durability evaluation, and a sound generation limit tension test was performed as a sound resistance evaluation.

  In the V-ribbed belts of Examples 4 to 7 and Comparative Example 3, the cords made of polyester fiber ropes were embedded in the belt body, the back surface (extension layer) was formed of a rubber layer, and the compression provided on the other surface side Three rib portions are arranged in the layer in the longitudinal direction of the belt. The stretched layer contains short fibers, and the short fibers are oriented in the width direction. Further, the compression layer is formed by flocking polyamide short fibers on the surface.

  Here, the compression layer was formed using an unvulcanized rubber sheet made of a rubber composition prepared according to the formulation shown in Table 1. The surface of the unvulcanized rubber sheet is formed by implanting polyamide short fibers by electrostatic flocking. As a belt manufacturing method, the following known methods were used. First, a stretched rubber sheet is wound on a flexible jacket mounted on a cylindrical molding drum, the core wire is spun, and further, the compressed rubber sheet is wound so that the flocked layer becomes the outer peripheral surface, and the unloaded A sulfur belt sleeve is formed. Then, the flexible jacket is expanded, the unvulcanized sleeve is pressed against an outer mold having a stamp corresponding to the rib portion, vulcanized, and the resulting vulcanized belt sleeve is cut into individual belts by a cutter. Thus, a V-ribbed belt was obtained. Then, using this V-ribbed belt, a heat resistance running test was performed as an evaluation of durability, and a sound generation limit tension test was performed as an evaluation of sound resistance.

Heat-resistant running test The running test machine comprises a driving pulley (diameter 120 mm), an idler pulley (diameter 85 mm), a driven pulley (diameter 120 mm), and a tension pulley (diameter 45 mm) arranged in this order. Then, a V-ribbed belt is hung on each pulley of the test machine, the winding angle of the V-ribbed belt around the tension pulley is 90 °, the winding angle around the idler pulley is 120 °, the ambient temperature is 120 ° C, the driving pulley A load was applied to the drive pulley under the test conditions of 4900 rpm and belt tension of 559 N / 3 ribs, and the V-ribbed belt was run for 500 hours. The V-ribbed belt was visually observed to examine the number of cracks generated in the compressed layer. The results are also shown in Table 1.

Sound generation limit tension test A V-ribbed belt is suspended at a predetermined belt tension between a driving pulley having a diameter of 135 mm, a first driven pulley having a diameter of 112 mm, and a second driven pulley having a clutch mechanism having a diameter of 60 mm. The squeal generated when the second driven pulley was rotated while rotating at 1,000 rpm, and the tone generation limit tension, which was the minimum tension of the belt at this time, were measured. In addition, a sounding limit tension test was performed on the V-ribbed belt after running for 180 hours under the condition of an ambient temperature of 85 ° C. (after running-in running) using the test machine used in the heat-resistant running test in the same manner as described above. In this sound production limit tension test, the sound production performance during water injection with water dropped at 60 cc / min is evaluated. The lower the sound production limit tension obtained by this measurement, the higher the noise suppression effect.

  As a result, it was found that the examples had a high effect of suppressing abnormal noise even when wet, without causing problems in durability, and the effect was maintained after running. Further, in Examples 4 to 6 containing an appropriate amount of lubricant, it was found that the sound-proofing property when wet was further improved and the durability was excellent. However, it was found that in Example 7 containing less than the proper amount of lubricant, the effect was not evident. On the other hand, the comparative example was inferior in belt durability, and in the comparative examples 1 and 2, the workability was very poor and there was a problem in practical use.

  The friction transmission belt according to the present invention can be attached to a drive device for automobiles or general industries.

It is sectional drawing of the V-ribbed belt which is a friction transmission belt which concerns on this invention. It is sectional drawing of another V-ribbed belt which is a friction transmission belt which concerns on this invention. It is sectional drawing of another V-ribbed belt which is a friction transmission belt which concerns on this invention.

Explanation of symbols

1, 21, 31 V-ribbed belt 2, 22 Adhesive layer 3, 23, 33 Core wire 4, 24, 34 Compression layer 5, 24, 35 Stretch layer 7, 27, 37 Rib portion 8, 28, 38 Back surface

Claims (12)

A friction transmission belt characterized in that at least a surface layer of a friction transmission portion is composed of a porous rubber composition having a cell rate of 5 to 20%, and the surface of the surface layer has irregularities .   The friction transmission belt according to claim 1, wherein the porous rubber composition is contained in a proportion of 50 to 150 parts by weight of the reinforcing filler with respect to 100 parts by weight of the rubber.   The friction transmission belt according to claim 2, wherein the reinforcing filler is carbon black. 4. The friction transmission belt according to claim 3, wherein the carbon black is a carbon black having a nitrogen adsorption specific surface area of 40 to 120 m < ² > / g and a dibutyl phthalate oil absorption of 80 to 130 cm < ³ > / 100 g.   The friction transmission belt according to any one of claims 1 to 4, wherein the porous rubber composition contains a lubricant.   The friction transmission belt according to claim 5, wherein the lubricant is contained at a ratio of 10 to 50 parts by weight with respect to 100 parts by weight of rubber.   The friction transmission belt according to claim 5 or 6, wherein the lubricant is a solid lubricant.   The friction transmission belt according to claim 7, wherein the solid lubricant is graphite and / or ultrahigh molecular weight polyethylene.   The friction transmission belt according to any one of claims 1 to 8, wherein the rubber is mainly composed of an ethylene / α-olefin elastomer.   The friction transmission belt according to any one of claims 1 to 9, wherein the friction transmission belt is a V-ribbed belt provided with a rib portion extending in a belt longitudinal direction.   The friction transmission belt according to claim 10, wherein at least a part of the rib portion surface is made of a porous rubber composition. The friction transmission belt according to claim 10 or 11, wherein at least a part of the back surface of the belt is made of a porous rubber composition.

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