JP2007092880A - Transmission belt - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a friction transmission belt capable of maintaining low coefficiency of friction for a long time, reducing generation of sound due to stick slip and misalignment, and having excellent resistance to wear and, to provide a manufacturing method for the friction transmission belt. <P>SOLUTION: In this V-ribbed belt 1 made of an elastic body layer including a rubber layer in which a core wire 2 is buried along the longitudinal direction of the belt, a rib part 6 which becomes a friction transmission face is constituted by a rubber component containing polyolefin short fibers having length of fiber of 0.2 to 8.0 mm of 5 to 50 pts.wt. for ethylene-α-olefin elastomer of 100 pts.wt. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

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

  The characteristics required for the friction transmission belt include not only the transmission of power but also the generation of abnormal noise during use, and excellent durability, particularly wear resistance. In order to satisfy these characteristics, the friction transmission part is composed of a rubber composition blended with short fibers such as polyamide, meta-aramid or para-aramid, and the friction transmission surface is covered with them to produce sound resistance and wear resistance. In general, improvement of adhesive wear resistance is achieved.

  However, in recent automobile engines, lean combustion is performed in order to reduce the size, improve fuel efficiency, and reduce exhaust gas. Therefore, engine rotational fluctuation and vibration are larger than those of conventional engines. In addition, the use of serpentine for auxiliary machinery has resulted in smaller pulleys and smaller bend engine layouts, and the load on the friction transmission belt has further increased, causing problems such as misalignment and noise generation due to stick-slip. Yes.

  In order to cope with such a problem by increasing the blending amount of the short fibers in the above-described method, a problem occurs in the physical properties and processability, the blending amount is limited, and the belt travels to the surface. There is a problem in that the effect of reducing the friction coefficient is reduced due to the falling off or abrasion of the organic short fibers protruding.

On the other hand, a friction transmission belt has been proposed in which at least a pulley contact portion of the belt body is formed of a rubber composition in which an ethylene / α-olefin elastomer contains a powdery or granular polyolefin resin. (For example, refer to Patent Document 1) According to the above-described configuration, the rubber component of the rubber composition constituting at least the pulley contact portion of the belt main body is an ethylene / α-olefin elastomer and has a low friction coefficient itself. In addition, a powdery or granular polyolefin resin is dispersed therein, and the coefficient of friction is reduced by the polyolefin resin exposed on the belt surface, so that low sound output and wear resistance are excellent. In addition, since the ethylene / α-olefin elastomer has a high affinity for the polyolefin resin, a good dispersion state of the polyolefin resin can be obtained.
JP 2004-324794 A

  However, in the method of Patent Document 1, the powdery or granular polyolefin resin acts as a lubricant, and the reinforcing property cannot be expected. In addition, it is possible to reduce the slip noise in the initial running stage of the belt, but in the belt after running for a long time, the polyolefin resin tends to fall off from the surface, so the effect of reducing the friction coefficient of the belt surface Could not be maintained over a long period of time. Further, in manufacturing the belt, depending on the conditions for mixing the polyolefin resin with the ethylene / α-olefin elastomer, there is a problem that the physical properties of the belt are drastically lowered.

  The present invention has been made in view of such problems, and can maintain a low coefficient of friction over a long period of time, reduce sound generation due to stick-slip and misalignment, and can be durable and resistant. It is an object of the present invention to provide a friction transmission belt excellent in wear resistance and a method for manufacturing the friction transmission belt.

  The invention according to claim 1 of the present application is a rubber composition in which the friction transmission surface contains 5 to 50 parts by weight of polyolefin short fibers having a fiber length of 0.2 to 8.0 mm with respect to 100 parts by weight of the ethylene / α-olefin elastomer. It is a friction transmission belt characterized by comprising a thing.

  The invention according to claim 2 of the present application is the friction transmission belt according to claim 1, wherein a part of the polyolefin short fiber is exposed from the friction transmission surface.

  Invention of Claim 3 of this application is a friction transmission belt of Claim 1 or 2, Comprising: Melting | fusing point or softening point of polyolefin short fiber is 100-250 degreeC, It is characterized by the above-mentioned.

  Invention of Claim 4 of this application is a friction transmission belt of any one of Claims 1-3, Comprising: Polyolefin short fiber is ultra high molecular weight polyethylene short fiber, It is characterized by the above-mentioned.

  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 friction transmission belt is a V-ribbed belt.

  In the invention according to claim 6, the friction transmission surface is blended with 5 to 50 parts by weight of a polyolefin short fiber having a fiber length of 0.2 to 8.0 mm with respect to 100 parts by weight of the ethylene / α-olefin elastomer, Alternatively, it is a method for producing a friction transmission belt, which is formed by vulcanizing and molding a rubber composition kneaded below the softening point above the melting point or softening point.

  The invention according to claim 7 of the present application is the method for producing a friction transmission belt according to claim 6, wherein rubber kneading is performed in at least two stages, and the kneading is performed in the final stage of kneading. To do.

  The invention according to claim 8 of the present application is the method for producing a friction transmission belt according to claim 6 or 7, wherein a part of the polyolefin short fiber is exposed from the friction transmission surface.

  Invention of Claim 9 of this application is a manufacturing method of the friction transmission belt of any one of Claims 7-9, Comprising: Melting | fusing point or softening point of polyolefin short fiber is 100-250 degreeC. Features.

  Invention of Claim 10 of this application is a manufacturing method of the friction transmission belt of any one of Claims 7-10, Comprising: Polyolefin short fiber is ultra high molecular weight polyethylene short fiber, It is characterized by the above-mentioned.

  Invention of Claim 11 of this application is a manufacturing method of the friction transmission belt of any one of Claims 7-11, Comprising: A friction transmission belt is a V-ribbed belt, It is characterized by the above-mentioned.

  The invention according to claim 1 of the present application is composed of a rubber composition containing a specific amount of a polyolefin short fiber having a fiber length of 0.2 to 8.0 mm in an ethylene / α-olefin elastomer in the friction transmission surface. Provided is a friction transmission belt having good wear resistance and excellent sound resistance and capable of reducing the coefficient of friction over a long period of time.

  In the invention according to claim 2 of the present invention, since a part of the polyolefin short fiber is exposed from the friction transmission surface, it is possible to reduce the coefficient of friction from the beginning of running, and thus durability, wear resistance, and sound resistance. Improves.

  The invention according to claim 3 of the present invention is that the polyolefin short fiber has a melting point or softening point of 100 to 250 ° C., so that the polyolefin short fiber can maintain a clear fiber shape in the rubber composition, and the elastomer and It also has excellent adhesion, and is excellent in durability, abrasion resistance, and sound resistance.

  In the invention according to claim 4 of the present application, the effect of reducing the friction coefficient is further enhanced because the polyolefin short fiber is an ultrahigh molecular weight polyethylene short fiber.

  In the invention according to claim 5, the friction transmission belt is a V-ribbed belt, sound generation due to stick-slip or misalignment is reduced, rib cracks are suppressed, and the belt can have a long life.

  The invention according to claim 6 is a rubber composition in which a specific amount of an ethylene / α-olefin elastomer and a short polyolefin fiber having a fiber length of 0.2 to 8.0 mm is blended and kneaded at a melting point or less than the softening point. A rubber composition containing a specific amount of a polyolefin short fiber having a fiber length of 0.2 to 8.0 mm in an ethylene / α-olefin elastomer as a friction transmission surface by forming a product by vulcanization molding at a melting point or a softening point or higher It can consist of things. That is, it becomes possible for the polyolefin short fibers to exist in the belt molded product while maintaining the fiber shape, and the adhesion between the short fibers and the ethylene / α-olefin elastomer is good, and the durability, wear resistance and It is possible to provide a friction transmission belt that has excellent sound resistance and can reduce the coefficient of friction over a long period of time.

  In the invention of claim 7, the rubber kneading is carried out in at least two stages, and by performing the kneading in the final stage of kneading, the polyolefin short fibers can maintain the fiber shape in the belt molded body, and Since it is possible to provide kneading at a high temperature before the final stage of kneading, there is an advantage that the kneading of the rubber and the other compounding agent can be performed satisfactorily.

  In the invention according to claim 8 of the present invention, by exposing a part of the polyolefin short fiber from the friction transmission surface, it is possible to reduce the coefficient of friction from the beginning of running, and as a result, durability, wear resistance, and sound resistance are improved. improves.

  The invention according to claim 9 of the present application is that the short fiber of the polyolefin has a clear fiber shape in the rubber composition even when kneading at a relatively high temperature because the melting point or softening point of the short fiber is 100 to 250 ° C. Furthermore, it is excellent in durability, wear resistance, and sound resistance.

  In the invention according to claim 10 of the present application, the effect of reducing the friction coefficient is further enhanced by the fact that the polyolefin short fibers are ultra high molecular weight polyethylene short fibers.

  In the invention according to claim 11 of the present application, the friction transmission belt is a V-ribbed belt, sound generation due to stick-slip or misalignment can be reduced, cracks in the rib can be suppressed, and the life of the belt can be extended.

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

  As shown in FIG. 1, the V-ribbed belt 1 includes an adhesive layer 3 in which a core wire 2 is embedded in the longitudinal direction of the belt, a compression layer 4 provided on one surface of the adhesive layer 3, and the other of the adhesive layer 3. And a stretch layer 5 made of a cover canvas covering the surface of the cover. The compressed layer 4 is provided with a plurality of rib portions 6 having a substantially triangular cross section extending in the belt longitudinal direction. Here, the friction transmission surface refers to the surface layer of the compression layer 6.

  The core wire 2 used in the present invention includes polyethylene terephthalate (PET) fiber, polyethylene naphthalate (PEN) fiber, polytrimethylene terephthalate (PTT) fiber, polybutylene terephthalate (PBT) fiber, polyparaphenylene benzobisoxazole (PBO). ) Twisted cords composed of fibers, polyamide fibers, glass fibers, aramid fibers, or the like can be used.

  The core wire is preferably subjected to an adhesive treatment. For example, (1) After impregnating the untreated cord into a tank containing a treatment liquid selected from an epoxy compound and an isocyanate compound, and pre-dip (2) 160 Dry in a drying oven set at a temperature of ~ 200 ° C for 30-600 seconds, (3) then immerse in a tank containing an adhesive solution consisting of RFL, and (4) set the temperature at 210-260 ° C The stretched heat fixing processor can be stretched by −1 to 3% for 30 to 600 seconds to form a stretched 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 deteriorates, 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 canvas constituting the stretch layer 5 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.

  Here, the compressed layer 4 is composed of a rubber composition containing 5 to 50 parts by weight of polyolefin short fibers having a fiber length of 0.2 to 8.0 mm with respect to 100 parts by weight of the ethylene / α-olefin elastomer.

  Examples of the ethylene / α-olefin elastomer include a copolymer of ethylene and α-olefin (propylene, butene, hexene, or octene), or a copolymer of ethylene, the α-olefin, and a nonconjugated diene. Specifically, it refers to rubber such as EPM and 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.

  The polyolefin short fiber used in the present invention has a fiber length of 0.2 to 8.0 mm, more preferably 0.5 to 6.5 mm. If the fiber length is less than 0.2 mm, the short fibers are likely to fall off the rubber surface, and it is difficult to maintain the effect of reducing the friction coefficient over a long period of time, and the reinforcing property is inferior. In addition, since it is difficult to achieve orientation in rolling or the like, there is a problem that it is not suitable when orientation is required. On the other hand, when it exceeds 8.0 mm, the dispersion of the olefin short fibers in the rubber composition is deteriorated, and the wear resistance, durability and the like are lowered. Polyolefins have good compatibility with ethylene / α-olefin elastomers, so that they are easily dispersed in a rubber composition, and as a result, a decrease in physical properties is suppressed and a stable low coefficient of friction is realized for a long time.

  Here, the melting point or softening point of the polyolefin short fiber is desirably 100 to 250 ° C. If it is less than 100 ° C., it is melted or softened in a process such as kneading, and it is difficult to maintain the fiber shape in the rubber composition, and it is difficult to ensure good wear resistance and durability. On the other hand, polyolefin short fibers exceeding 250 ° C. are very expensive, resulting in high blending costs.

  Specific examples of the polyolefin include polypropylene and polyethylene. Among them, it is desirable to select ultrahigh molecular weight polyethylene having a high friction coefficient reducing effect. Ultra high molecular weight polyethylene is a generic term for those having an average molecular weight of 1,000,000 g / mol or more by the viscosity method and 3,000,000 g / mol or more by the light scattering method. A molecular weight of 3 million to 8 million g / mol is preferred. The ultrahigh molecular weight polyethylene preferably has a melting point or softening point of 100 to 150 ° C.

  The polyolefin short fiber is contained in an amount of 5 to 50 parts by weight with respect to 100 parts by weight of the ethylene / α-olefin elastomer. If it is less than 5 parts by weight, it is difficult to maintain the effect of reducing the friction coefficient over a long period of time. On the other hand, if it exceeds 50 parts by weight, there is a problem that durability is lowered.

  The rubber composition preferably contains short fibers other than the polyolefin short fibers. For example, short fibers made of polyamide, polyester, cotton, aramid, PBO, etc. are mixed to improve the side pressure resistance of the compression layer 4 and the short fibers protrude from the surface of the compression layer 4 that is in contact with the pulley. Thus, it is possible to reduce the friction coefficient of the compression portion and reduce noise during belt running. In particular, when at least one of an aramid short fiber and a polyamide short fiber is included, an effect of maintaining a low friction coefficient for a long time can be obtained. 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 fiber has a fiber length of 1 to 20 mm, and the addition amount is preferably 5 to 50 parts by weight with respect to 100 parts by weight of rubber. When the amount of short fibers added is less than 1 part by weight, there is a drawback that the rubber of the compression layer 4 tends to stick and wear, and when it exceeds 40 parts by weight, the short fibers are uniformly in the rubber. Difficult to disperse. In order to improve the adhesion of the short fibers to the rubber of the compression layer 4, it is preferable that the short fibers are subjected to an adhesion treatment with a treatment liquid containing an epoxy compound, an isocyanate compound, or the like.

  The rubber composition can contain an organic peroxide as a crosslinking agent. Examples of the organic peroxide include dicumyl peroxide, di-t-butyl peroxide, t-butylcumyl peroxide, benzoyl peroxide, 1,3-bis (t-butylperoxyisopropyl) benzene, 2,5 -Dimethyl-2,5-di (t-butylperoxy) hexyne-3,2,5-dimethyl-2,5- (benzoylperoxy) hexane, 2,5-dimethyl-2,5-mono (t- Butyl peroxy) hexane and the like. This organic peroxide is preferably used alone or as a mixture in the range of 0.5 to 8 parts by weight with respect to 100 parts by weight of the polymer component.

  Further, the rubber composition may contain 0.5 to 13 parts by weight of N, N'-m-phenylene dimaleimide and / or quinonedioxime with respect to 100 parts by weight of the polymer component. N, N′-m-phenylene dimaleimide and / or quinonedioxime acts as a co-crosslinking agent, and if less than 0.5 part by weight, the effect of addition is not significant, and if it exceeds 13 parts by weight, tearing force and adhesion The force drops sharply. 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.

  Examples of quinone dioximes include p-benzoquinone dioxime, p, p'-dibenzoquinone dioxime, and tetrachlorobenzoquinone poly (P-dinitrobenzoquinone). In view of adhesiveness and crosslink density, benzoquinone dioximes such as p-benzoquinone dioxime and p, p'-dibenzoquinone dioxime are preferred.

  Moreover, inorganic fillers, such as carbon black, metal carbonate, metal silicate, can be mix | blended with the said rubber composition. Considering the reinforcing property, it is desirable that at least carbon black is contained.

Carbon black is not limited, it is preferable that the nitrogen adsorption specific surface area 20~150cm ² / g, DBP oil absorption amount is used which has the properties of 50~160cm ³ / 100g. 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 DBP oil absorption (dibutyl phthalate oil absorption) is a structure index and is measured according to JIS K 6217-4.

  Examples of the metal carbonate include calcium carbonate, and examples of the metal silicate include calcium silicate, potassium aluminum silicate, aluminum silicate, and magnesium silicate. More specifically, examples of aluminum silicate include clay, examples of magnesium silicate include talc, and examples of potassium aluminum silicate include mica. These can be used alone or in combination. Of these, calcium carbonate is desirable because it has good compatibility with rubber and does not adversely affect mechanical properties such as strength.

  The average primary particle size of the inorganic filler is preferably 0.01 to 3.00 μm. If it exceeds 3.00 μm, there is a problem that the durability of the belt is adversely affected. If it is less than 0.01 μm, the dispersibility is poor and the rubber physical properties are not uniform.

  In addition to that, those used in ordinary rubber compounds such as short fibers, anti-aging agents, plasticizers, softeners, stabilizers, processing aids, and colorants are used as necessary.

  The adhesive layer 3 is desirably made of a blend rubber obtained by mixing ethylene / α-olefin rubber alone or a partner rubber made of other kinds of rubber as a rubber component. As the other rubber blended with ethylene / α-olefin rubber, butadiene rubber (BR), styrene / butadiene rubber (SBR), nitrile rubber (NBR), hydrogenated nitrile rubber (H-NBR), chloroprene rubber (CR), Mention may be made of at least one rubber of butyl rubber (IIR) and natural rubber (NR). Of course, it is also possible to use the same rubber composition as described above.

  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, a V-ribbed belt in which rubber is exposed without attaching a canvas to the back, and the like 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 stretch layer 25 formed of a rubber composition with a back surface 28 provided with a flocking layer 24, and an adhesive layer 22 disposed below the stretch layer 25. The layer 26 is arranged. The core wire 23 is embedded in the main body along the longitudinal direction of the belt, and a part thereof is in contact with the stretched layer 25 and the remaining part is in contact with the adhesive layer 22. The compressed layer 26 is provided with a plurality of ribs 27 having a substantially triangular cross section extending in the belt longitudinal direction. Here, the short fibers contained in the compressed layer 26 exhibit a flow state along the rib shape, and the short fibers near the surface are oriented along the rib shape.

  A V-ribbed belt 31 shown in FIG. 3 has a configuration in which a back surface 38 is formed of a rubber layer containing a short fiber 34 and a compression layer 36 is 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 36. The compression layer 35 is provided with a plurality of ribs 37 having a substantially triangular cross section extending in the belt longitudinal direction, and a flocking layer 39 is provided on the rib surface. Here, the short fibers contained in the stretched layer 25 are oriented in a random direction.

  Here, FIG. 3 shows a configuration in which the stretch layer 35 is not formed of a canvas and is formed of a rubber composition containing short fibers, but at this time, in order to suppress abnormal noise during driving of the back surface, An uneven pattern can be provided. 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. Moreover, as a short fiber, polyester, aramid, nylon, cotton, etc. can be mix | blended as desired. In addition, the same rubber composition as that described above can be used for the rubber composition and the core wire constituting the stretch layer, the compression layer and the adhesive layer.

  In FIG. 3, the short fibers contained in the stretched layer 35 are oriented in a random direction, but may be oriented in one direction such as in the belt width direction. 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 36. 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 36 is made of a rubber composition containing no short fibers.

  In FIG. 2, the stretch layer 25 has a structure in which the flocked layer 24 is provided on the surface of the rubber composition that does not contain short fibers, but a flocked layer is provided on the surface of the rubber composition that contains short fibers. It is also possible.

  In FIG. 2, the short fibers contained in the compressed layer 26 are in a flow state along the rib shape, but the short fibers may be oriented in the width direction.

  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.

  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. 2, the short fibers contained in the compressed layer 26 are in a flow state along the rib shape. The V-ribbed belt is manufactured by, for example, the second method, the third method, or the fourth method. Can be obtained. And the V-ribbed belt in which the short fibers contained in the compressed layer are oriented in the width direction can be obtained by, for example, the first method.

  Here, the rubber composition which comprises a compression rubber sheet can be prepared as follows. In the present invention, the kneading of the rubber and the compounding agent is desirably performed in at least two stages. Specifically, using a kneader such as a Banbury mixer or a kneader, a compounding agent other than the polyolefin short fiber and the crosslinking agent and the ethylene / α-olefin elastomer are blended, and the first stage kneading is performed. The kneading temperature at this time can be carried out at a relatively high temperature equal to or higher than the melting point or softening point of the polyolefin short fibers. The main kneading can be carried out in a plurality of times.

  Next, at a temperature lower than the melting point or softening point of the polyolefin short fiber, the kneaded product is blended with the polyolefin short fiber and the crosslinking agent and blended, and the final stage of kneading is performed. At this time, if the kneading temperature is set to be equal to or higher than the melting point or the softening point, it becomes difficult to maintain the fiber shape by melting or softening the polyolefin short fibers, and the effect of lowering the friction coefficient is reduced. Even in an unvulcanized state, it becomes rigid, and a problem that molding after kneading becomes difficult occurs. That is, by setting the kneading temperature below the melting point or softening point, the rubber composition can be contained in the rubber composition while maintaining the fiber shape of the polyolefin short fibers. And a compression rubber sheet can be produced by rolling the rubber composition prepared in this way. In this rolling step, the polyolefin short fibers can be oriented in a specific direction.

  The unvulcanized belt sleeve formed using the compressed rubber sheet is vulcanized at a temperature equal to or higher than the melting point or softening point of the polyolefin short fibers. As a result, the melted or softened state is approached or melted or softened while retaining shape retention, and the affinity of the interface between the short fiber and the ethylene / α-olefin elastomer is increased.

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

  Hereinafter, a description will be given with specific examples.

<Evaluation of shape retention of polyolefin short fibers>
Example 1
Using a Banbury mixer, carbon black and paraffin oil are mixed with EPDM and kneaded until the rubber temperature reaches 165 ° C. After the rubber is discharged and cooled to about 50 ° C, the kneaded rubber is mixed with the rubber. Organic peroxides and ultra high molecular weight polyethylene short fibers (average molecular weight (viscosity method) 400,000, fiber length 1.0 mm, melting point 145 ° C.) were mixed and kneaded at a temperature of 120 ° C. or lower. This rubber composition was rolled with a calender roll to obtain a rubber sheet, and vulcanized at 150 ° C. for 30 minutes. When the obtained vulcanized rubber was observed with an SEM, it was confirmed that the ultrahigh molecular weight polyethylene short fibers maintained the fiber shape as shown in FIG. (The center of the photograph is an ultrahigh molecular weight polyethylene short fiber) and the orientation was also confirmed.

Example 2
A vulcanized rubber was produced in the same manner as described above except that the vulcanization condition was changed to 180 ° C. for 30 minutes, and observed with an SEM. As a result, it was confirmed that the ultrahigh molecular weight polyethylene short fiber maintained the fiber shape. did it.

Comparative Example 1
A vulcanized rubber was produced in the same manner as in Example 1 except that the mixing temperature of the ultrahigh molecular weight polyethylene short fibers was set to 150 ° C. As a result, the rubber became stiff after the kneading and the workability was extremely poor. Further, when the obtained vulcanized rubber was observed with an SEM, the presence of short fibers could not be recognized.

<Evaluation of friction, wear resistance and heat durability of V-ribbed belt>
Examples 3-6, Comparative Examples 2-5
A rubber composition was prepared according to the formulation shown in Table 1. Using a Banbury mixer, EPDM was mixed with compounding agents other than organic peroxides and short polyolefin fibers, kneaded until the rubber temperature reached 165 ° C, discharged and cooled to about 50 ° C. Thereafter, an organic peroxide and ultrahigh molecular weight polyethylene short fibers (average molecular weight (viscosity method) 400,000, melting point 145 ° C.) were mixed with the kneaded rubber and kneaded at a temperature of 120 ° C. or lower. The obtained rubber composition was rolled with a calender roll to obtain a rubber sheet, which was vulcanized by pressing at 165 ° C for 30 minutes, and the hardness (JIS-A) of the obtained vulcanized rubber was measured according to JIS K6253. did.
Comparative Example 3 does not contain ultrahigh molecular weight polyethylene short fibers in rubber, and Comparative Example 5 uses CR instead of EPDM as a rubber component.

  Next, a V-ribbed belt was produced. In the V-ribbed belt, a cord made of a polyester fiber rope is embedded in the belt body, the back surface (extension layer) is formed of a rubber layer, and three rib portions are formed on the compression layer provided on the other surface side of the belt. It is arranged in the longitudinal direction. The compression layer and the stretch layer contain short fibers, and the short fibers are oriented in the belt width direction.

  Here, the compression layer and the stretch layer were formed using the unvulcanized rubber sheet. As a belt manufacturing method, the following known methods were used. First, a stretched rubber sheet is wound around a flat cylindrical molding mold, the core wire is spun, and further, after the compressed rubber sheet is wound, a vulcanization jacket is inserted on the compressed rubber sheet. 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. When the ground surface was confirmed, it was confirmed that a part of the ultra high molecular weight polyethylene short fiber was exposed. The V-ribbed belt was used for evaluation of friction, wear resistance, and heat durability.

As shown in FIG. 5, the running test machine used for the evaluation of the heat durability test includes a driving pulley 40 (diameter 60 mm), an idler pulley 41 (diameter 50 mm), a driven pulley 42 (diameter 50 mm), and a tension pulley 43. (Diameter 50 mm) and idler pulley 44 (diameter 50 mm) are arranged in order. Then, the V-ribbed belt 1 is hung on the pulleys 40 to 44 of the test machine, the winding angle of the V-ribbed belt 1 around the idler pulleys 41 and 44 is 90 °, the ambient temperature is 130 ° C., and the rotational speed of the drive pulley is 3300 rpm. Under the test conditions of belt tension of 800 N / rib, a load was applied to the drive pulley 40 to run the V-ribbed belt 1, and 500 hours were discontinued, and the time until six cracks reaching the core line were examined. Note that the test was terminated for 400 hours.

Abrasion test In the abrasion test, each V-ribbed belt is installed at a driving pulley (diameter 120 mm) and a driven pulley (diameter 120 mm) on an idler pulley (diameter 45 mm) at room temperature. After running for 48 hours at .3 kgf and 800 rpm, the belt wear rate was measured. The wear rate was calculated by measuring the belt weight before and after the running test and dividing the belt weight loss (belt weight before running−belt weight after running) by the belt weight before running as the wear rate.

Friction test In the friction test, a V-ribbed belt is hung on a guide roller so that the winding angle of the V-ribbed belt is 90 °, one end of the V-ribbed belt is fixed, and a weight of 2.0 kgf is suspended at the other end. By detecting the value of the load cell when the roller is rotated at 43 rpm, the tension T1 on the tension side and the tension T2 on the loose side are detected. From the tension ratio (T1 / T2), the friction coefficient μ = (1 / 2π ) Ln (T1 / T2) was determined. In addition, the friction test was implemented about the belt (original) before a heat endurance test, and the belt (after deterioration) after a heat endurance test.
These results are shown in Table 2.

  As a result, it can be seen that the example is a V-ribbed belt that can maintain a low coefficient of friction over a long period of time, has excellent wear resistance, and has high durability. However, in Comparative Example 2 in which only a small amount of ultrahigh molecular weight polyethylene short fibers was blended and in Comparative Example 3 in which no ultrahigh molecular weight polyethylene short fibers were contained, there was an extreme difference in the coefficient of friction before and after the heat resistance durability test. It was also found that Comparative Example 3 had a high coefficient of friction at the beginning of running and poor wear resistance. In Comparative Example 4 in which ultra-high molecular weight polyethylene short fibers are excessively blended and Comparative Example 5 in which ultra-high molecular weight polyethylene short fibers having a long fiber length are blended, the heat resistance durability is extremely low, and it is not possible to run until the cutoff time. It was. In addition, the abrasion resistance was insufficient as compared with the examples. And in the comparative example 6 which used CR for the rubber component, the heat resistance durability and the wear resistance were extremely poor, and were practically impossible.

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

It is a section perspective view of the V ribbed belt which is a friction transmission belt concerning the present 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. It is a SEM image of the vulcanized rubber composition concerning the present invention. It is a figure which shows the layout of the heat-resistant durability test in an Example.

Explanation of symbols

1 V-ribbed belt 2 Core wire 3 Adhesive layer 4 Compression layer 5 Stretch layer 6 Rib part

Claims (11)

  The friction transmission surface is composed of a rubber composition containing 5 to 50 parts by weight of polyolefin short fibers having a fiber length of 0.2 to 8.0 mm with respect to 100 parts by weight of the ethylene / α-olefin elastomer. Friction transmission belt.   The friction transmission belt according to claim 1, wherein a part of the polyolefin short fiber is exposed from the friction transmission surface.   The friction transmission belt according to claim 1 or 2, wherein the polyolefin short fiber has a melting point or softening point of 100 to 250 ° C.   The friction transmission belt according to any one of claims 1 to 3, wherein the polyolefin short fibers are ultra high molecular weight polyethylene short fibers.   The friction transmission belt according to any one of claims 1 to 4, wherein the friction transmission belt is a V-ribbed belt.   A rubber composition in which 5 to 50 parts by weight of a polyolefin short fiber having a fiber length of 0.2 to 8.0 mm is mixed with a friction transmission surface of 100 parts by weight of an ethylene / α-olefin elastomer and kneaded at a melting point or less than a softening point. A method for producing a friction transmission belt, characterized in that an object is formed by vulcanization molding at a melting point or a softening point or higher.   The method for producing a friction transmission belt according to claim 6, wherein the rubber is kneaded at least in two stages, and the kneading is performed in a final stage.   The method for producing a friction transmission belt according to claim 6 or 7, wherein a part of the polyolefin short fiber is exposed from the friction transmission surface.   The method for producing a friction transmission belt according to any one of claims 6 to 8, wherein the polyolefin short fiber has a melting point or softening point of 100 to 250 ° C.   The method for producing a friction transmission belt according to any one of claims 6 to 9, wherein the polyolefin short fibers are ultra high molecular weight polyethylene short fibers. The method for manufacturing a friction transmission belt according to any one of claims 6 to 10, wherein the friction transmission belt is a V-ribbed belt.

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