JP2007118218A - Manufacturing method of friction transmission belt - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a V-ribbed belt having high heat-resistant bending properties, excellent abrasion resistance and sound emission resistance. <P>SOLUTION: The V-ribbed belt 1 is constituted of a stretched part 5 comprising a rubber layer in which short fibers are oriented at random, an adhesive part 2 in which core wires 3 comprising a twist yarn cord are embedded and the compression part 6 arranged under the adhesive part 2. The core wires 3 partially come into contact with the stretched part 5 and the remainder of them is brought into contact with the adhesive part 2. The compression part 6 has a plurality of trapezoidal ribs extending in the longitudinal direction of the belt and having an almost triangular cross section. A flocking layer 9 having a solid lubricant 9a and short fibers 9b is arranged to the side surface 9 of each of the ribs and can be formed by forming an adhesive layer using an adhesive, which is prepared by adding 20-70 wt.% of the solid lubricant with an average primary particle size of 0.15-20 μm to an unvulanized rubber constituting a friction transmission surface and fixing the short fibers to the adhesive layer before vulcanizing the whole. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a method of manufacturing a friction transmission belt used for power transmission of a drive device or the like.

  There is a demand for higher performance and higher performance in the rubber industry field, especially automotive parts. Among rubber products used for automobile parts, there is a power transmission belt, which is widely used for power transmission of auxiliary machines such as an air compressor and an alternator of an automobile.

  In recent years, there has been a strict demand for quietness. In particular, in a driving device, since sounds other than engine sounds are abnormal sounds, there is a demand 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 adhesive rubber adhering to the groove bottom between ribs as a result of compression rubber causing adhesive wear. Has been pointed out. In addition, there is a problem in that the belt runs unevenly due to misalignment of the pulley layout, and the passengers feel uncomfortable due to the generation of abnormal noise based on the uneven load.

  In response to these problems, by embedding a short fiber group such as cotton, nylon, vinylon, rayon, and aramid fiber in the compressed rubber while maintaining the orientation to the belt width, the side pressure resistance of the friction transmission part of the belt is improved. In general, a part of the embedded short fiber is intentionally protruded from the side surface of the belt to aim at the friction performance of the rib portion and the effect of suppressing the sound generation. However, in order to exert the slip suppression effect in the belt, it is necessary to intentionally expose the short fibers on the rib surface, and this requires a step of orienting in the belt width direction and a step of polishing the rib surface. Therefore, there is a problem that the cost of the belt becomes high. In addition, since most of the blended short fibers are embedded in the compressed rubber, the amount of exposure to the rib surface is small for the blended amount of short fibers, and the slip suppression effect could not be sufficiently obtained. . On the other hand, if the amount of exposure is to be increased, it is necessary to add a large amount of short fibers to the compressed rubber, and there is a problem that flexibility is lowered.

On the other hand, a V-ribbed belt in which short fibers are fixed only on the rib surface layer has also been proposed. Specifically, there is a V-ribbed belt in which an elastomer layer containing short fibers, fluororesin powder and / or non-ferrous metal powder is provided on the rib surface. (For example, see Patent Document 1)
US Patent 2004/0048708

  Such a V-ribbed belt is obtained by rolling a rubber sheet containing 0.15 to 0.25 mm formed by rolling a rubber composition containing rubber, a vulcanizing agent, short fibers, fluororesin powder and / or non-ferrous metal powder. It is manufactured by applying to the surface of the compressed layer of the sleeve and vulcanizing. However, since it is necessary to prepare the rubber composition for the surface layer in addition to the rubber composition for the belt main body, there is a problem that the manufacturing process increases and the cost increases. In addition, in order to ensure good processability and moldability, the amount of fibers and fluororesin powder and / or non-ferrous metal powder added to the rubber composition is limited, which makes it difficult to contain a large amount. there were.

  As a result of intensive research in view of the above problems, the present invention is proposed, and the object of the invention is to provide a friction transmission belt that is quiet and wear-resistant and also has excellent heat-resistant flexibility. It is in providing the method of manufacturing simply.

  In the invention of claim 1 of the present application, an adhesive layer is formed using an adhesive containing 20 to 70% by weight of a solid lubricant having an average primary particle size of 0.15 to 20 μm on unvulcanized rubber constituting the friction transmission surface. Then, after fixing the short fibers to the adhesive layer, vulcanization is performed to form a flocking layer in which the solid lubricant and the short fibers are fixed on the friction transmission surface. It is a manufacturing method.

  The invention according to claim 2 of the present application is the method for producing a friction transmission belt according to claim 1, wherein the solid lubricant is polytetrafluoroethylene.

  The invention of claim 3 of the present application is the method for manufacturing the friction transmission belt according to claim 1 or 2, wherein the friction transmission belt is a V-ribbed belt.

  By forming an adhesive layer using an adhesive containing a specific amount of a solid lubricant having a specific particle size on the unvulcanized rubber constituting the friction transmission surface, the short fibers can be easily formed into the adhesive layer in the next step. The flocking layer having a uniform flocking density can be formed on the friction transmission surface by performing vulcanization. In addition, when forming the flock layer in which the solid lubricant and the short fibers are fixed, if the solid lubricant and the short fibers are used in the adhesive, the viscosity of the adhesive is increased and the handleability is deteriorated. Since the adhesive containing a solid lubricant is used and the short fibers are fixed to the adhesive layer containing the solid lubricant, there is an effect that the adhesive is easy to handle. The obtained friction transmission belt has a low friction coefficient, is excellent in quietness, and has high heat durability and high wear resistance.

  Further, by selecting polytetrafluoroethylene as the solid lubricant, lower friction characteristics, wear resistance, and quietness are enhanced. And by applying to a V-ribbed belt, a V-ribbed belt excellent in friction characteristics, sound resistance and heat durability can be manufactured.

FIG. 1 shows a cross-sectional view of a V-ribbed belt as an embodiment of a friction transmission belt according to the present invention.
The V-ribbed belt 1 has a configuration in which an extension portion 5 made of a rubber layer in which short fibers are randomly oriented, an adhesive portion 2 in which a core wire 3 made of a twisted cord is embedded, and a compression portion 6 are disposed below the extension portion 5. A part of the core wire 3 is in contact with the extending portion 5, and the remaining portion is in contact with the bonding portion 2. The compression portion 6 has a plurality of trapezoidal ribs having a substantially triangular cross section extending in the belt longitudinal direction, the ribs serving as friction transmission portions, and the rib surfaces serving as friction transmission surfaces, and a flocking layer on the friction transmission surfaces. 9 is provided.

  In the present invention, the flocking layer 9 has a solid lubricant 9a and short fibers 9b. The solid lubricant 9a and the short fibers 9b are fixed to the friction transmission surface via an adhesive, but may be partially embedded or fixed to the rubber constituting the friction transmission surface. . With this configuration, effects such as low friction characteristics, wear resistance, and sound generation characteristics can be obtained.

  The solid lubricant 9a has an average primary particle size of 0.15 to 20 μm. If the thickness is less than 0.15 μm, the effect of reducing the friction coefficient is poor. On the other hand, if the thickness exceeds 20 μm, it becomes a foreign substance and cracks tend to occur, which may lead to a decrease in the durability life. Specifically, graphite, molybdenum disulfide, mica, talc, antimony trioxide, molybdenum diselenide, tungsten disulfide, polytetrafluoroethylene (PTFE), or the like can be used alone or in combination. Of these, PTFE is preferable in consideration of low friction characteristics, wear resistance, and quietness.

  Examples of the short fibers 9b include polyamide short fibers such as 6 nylon and 66 nylon, rayon short fibers, aramid short fibers such as p-aramid and m-aramid, cotton short fibers, and polyethylene short fibers. It is preferable to use short fibers having a fiber diameter of 5 to 36 μm and a fiber length of 0.2 to 2.0 mm.

The density of the short fibers 9b in the flocked layer 9 contributes to the friction coefficient and the sound during running. Specifically, it is preferably 10,000 to 500,000 pieces / cm ^2, but is not limited thereto. Moreover, it is preferable that the flock layer 9 has a thickness of 0.05 to 0.5 mm. If it is less than 0.05 mm, there is a problem that the effect of the flocked layer is diminished by abrasion. On the other hand, when the thickness exceeds 0.5 mm, the stretchability of the surface of the compressed portion is impaired, and thus the bending fatigue resistance is poor.

  The compression part 6 constituting the power transmission surface is composed of a rubber composition, and the raw rubber is natural rubber, butyl rubber, styrene-butadiene rubber, chloroprene rubber, alkylated chlorosulfonated polyethylene, ethylene-α-olefin rubber, hydrogen A rubber material such as a polymerized nitrile rubber, a mixed polymer of a hydrogenated nitrile rubber and an unsaturated carboxylic acid metal salt, or a mixture thereof can be used. Among these, ethylene / α-olefin rubber is preferably used because it has excellent ozone resistance, heat resistance, and cold resistance, is relatively inexpensive, and satisfies the requirement of dehalogenation. 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.

  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, and the like, and thiuram 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-crosslinking agent (co-agent), the degree of crosslinking can be increased to prevent problems such as adhesive wear. Examples of co-crosslinking agents include TAIC, TAC, 1,2 polybutadiene, metal salts of unsaturated carboxylic acid, 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 the 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 crosslink 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 quinonedioximes are selected, there is a feature that the adhesiveness with the fiber base material is excellent.

  Furthermore, by adding a solid lubricant to the rubber composition, sound resistance can be improved. As the solid lubricant, those described above can be used alone or in combination. Preferably, at least one selected from graphite, molybdenum disulfide, and PTFE is used. The solid lubricant is added in an amount of 10 to 100 parts by weight, more preferably 10 to 60 parts by weight with respect to 100 parts by weight of rubber. If the amount is less than 10 parts by weight, the friction coefficient of the belt surface does not change so much. If the inhibitory effect is not remarkable and the other amount exceeds 100 parts by weight, the elongation of the rubber properties is reduced, and the belt life is shortened.

  In addition to the above-mentioned vegetable soft granules, if necessary, it can be added to usual rubber compounds such as carbon black, reinforcing agents such as silica, fillers, plasticizers, stabilizers, processing aids, colorants, short fibers. What is used can be used.

  The adhesive part 2 can be made of the same rubber composition as that of the compression part 6, but may be made of another rubber composition. Although raw rubbers and compounding agents as described above can be used, it is preferable that short fibers are not mixed in consideration of adhesiveness.

  Core 3 is polyethylene terephthalate (PET) fiber, polyethylene naphthalate (PEN) fiber, polytrimethylene terephthalate (PTT) fiber, polybutylene terephthalate (PBT) fiber, polyparaphenylene benzobisoxazole (PBO) fiber, polyamide fiber A twisted yarn cord made of glass fiber or aramid fiber can be used.

  The core 3 is preferably subjected to an adhesive treatment. For example, (1) After impregnating the untreated cord with a tank containing a treatment liquid selected from an epoxy compound and an isocyanate compound, and pre-dip (2) It is dried by passing it through a drying oven set at 160 to 200 ° C. for 30 to 600 seconds, and (3) is subsequently immersed in a tank containing an adhesive solution made of RFL solution, and (4) is heated to 210 to 260 ° C. It can be stretched by −1 to 3% through a set stretching heat setting processor for 30 to 600 seconds 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 weight ratio between the resorcin / formaldehyde initial condensate and the rubber latex is preferably 1: 2 to 1: 8, and if this range is maintained, it is suitable for increasing the adhesive strength. 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), and 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 1 using the core 3 has a tensile force required to stretch the V-ribbed belt by 2% to 100 to 250 N / rib, more preferably 130 to 210 N / rib, even if the belt is stretched due to wear of rib rubber or the like. Even when this occurs, a stable tension can be maintained without causing a rapid drop in tension. If it exceeds 250 N / rib, a rapid drop in tension is observed when the belt is stretched, and if it is less than 100 N / rib, the belt tension is greatly lowered due to the core elongation.

  Further, when the belt is subjected to an initial load of 147 N / 5 cords and left to stand in an atmosphere of 100 ° C. for 30 minutes, the belt has a shrinkage force during dry heat of 50 to 150 N / 5 cords. Even if it occurs, the tension can be self-adjusted, and a belt with a low belt slip ratio and a long belt life can be obtained without installing an auto tensioner. When the belt shrinkage force is less than 50 N, the performance of adjusting the belt tension is poor and the slip rate tends to increase. Further, when the belt shrinkage force during dry heat exceeds 150 N, the belt length shrinkage with time tends to increase and the effect of reducing the slip ratio is small.

  The stretcher 5 can be made of the same rubber composition as that of the compressor 6, but may be made of another rubber composition. Here, the extending portion 5 is formed of a rubber composition containing short fibers, but an uneven pattern can also be provided on the back surface in order to suppress abnormal noise when driving the back 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. Moreover, as a short fiber, short fibers, such as polyester, aramid, polyamide, cotton, and PBO, can be mix | blended as desired. In FIG. 1, the short fibers are oriented in a random direction, but they 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. As the milled fiber, for example, a polyamide fiber can be used, and the fiber length is preferably in the range of 0.1 to 3.0 mm. Moreover, it is desirable that the amount of the short fiber in the stretched portion is such that the short fiber is contained so that the short fiber is in a range of 35 to 100 with respect to 100 parts by weight of the rubber.

  Note that the V-ribbed belt is not limited to the configuration shown in FIG. 1, and for example, a V-ribbed belt without an adhesive portion, a V-ribbed belt with a canvas attached 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 configuration in which a stretched portion 25 formed of a rubber composition having a flocked layer 28 provided on the back surface and a compressing portion 26 disposed below the stretched portion 25. 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 extension portion 25 and the remaining portion is in contact with the compression portion 26. The compression portion 26 is provided with a plurality of ribs having a substantially triangular cross section extending in the belt longitudinal direction. Here, the short fiber contained in the compression part 26 exhibits the flow state along the rib shape, and the short fiber near the surface is oriented along the rib shape. And the flock layer 29 which has the solid lubricant 29a and the short fiber 29b is arrange | positioned on the rib surface.

  A V-ribbed belt 31 shown in FIG. 3 has a configuration in which an extension portion 35 is formed by adhering canvas 34, an adhesive portion 32 is provided below the extension portion 35, and a compression portion 36 is further provided below the extension portion 35. Have The core wire 33 is embedded in the bonding portion 32 along the belt longitudinal direction. The compression portion 36 is provided with a plurality of ribs having a substantially triangular cross section extending in the belt longitudinal direction. And the flocked layer 39 which has the solid lubricant 39a and the short fiber 39b is arrange | positioned on the rib surface.

  In the case of the configuration in which the adhesive portion is not disposed as shown in FIG. 2, the core wire 23 is embedded in the belt main body at the boundary region between the extension portion 25 and the compression portion 26. At this time, in consideration of the adhesiveness between the core wire 23 and the belt body, it is desirable that one of the rubber layers of the extending portion 25 and the compressing portion 26 is made of a rubber composition not containing short fibers.

  In FIG. 2, the stretched portion 25 has a structure in which the flocked layer 28 is provided on the surface of the rubber composition that does not contain short fibers. However, the flocked layer may be provided on the surface of the rubber composition that contains short fibers. Is possible.

  Furthermore, in FIG. 2, although the short fiber contained in the compression part 26 is exhibiting the flow state along rib shape, it is good also as a structure which the short fiber orientated in the width direction.

  3 is a fiber base material selected from a woven fabric, a knitted fabric, a 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 34 is preferably immersed in the RFL liquid according to a known technique. Further, after immersing in the RFL solution, friction can be performed by rubbing the unvulcanized rubber into the cover canvas 5, 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 weight.

  When the V-ribbed belt performs back surface transmission, the surface of the extending portion can also be a friction transmission surface. Therefore, the extension part can also be provided with the flocking layer 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, after winding a compression rubber sheet constituting a compression part and an adhesive rubber sheet constituting an adhesion part around a cylindrical molding drum provided with rib markings on the peripheral surface, the core wire is spun, An unvulcanized sleeve is arranged by winding a member constituting the extension portion. Thereafter, the unvulcanized sleeve is vulcanized while being pressed against the molding drum, whereby a rib is formed on the compression portion. 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 second method, after winding a member constituting an extension part and an adhesive rubber sheet constituting an adhesive part on a flexible jacket mounted on a cylindrical molding drum, and spinning a core wire thereon Further, the compressed rubber sheets constituting the compression part 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 third method, after forming a first unvulcanized sleeve in which a compressed rubber sheet constituting a compression portion 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 in close contact, and then the member constituting the extension part and the adhesive rubber sheet constituting the adhesion part 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.

  In addition, the V-ribbed belt which does not arrange | position an adhesive part like FIG. 2 can be obtained by manufacturing without arrange | positioning an adhesive rubber sheet in the said method. Further, as shown in FIG. 2, the short fibers contained in the compression portion 26 are in a flow state along the rib shape. The V-ribbed belt is manufactured by, for example, the first method, the second method, or the third method. Can be obtained.

  Here, as a method of forming the compression part having the flocking layers 9, 29, 39, use of a compressed rubber sheet having the flocking layers 9 ', 29', 39 'can be mentioned. A compressed rubber sheet having a flocking layer can be produced by forming an adhesive layer in which a solid lubricant is fixed on the surface of an unvulcanized rubber sheet, and attaching short fibers on the adhesive layer.

  That is, an adhesive layer to which the solid lubricant is fixed is formed on the surface of the unvulcanized rubber sheet using an adhesive containing 20 to 70% by weight of a solid lubricant having an average primary particle size of 0.15 to 20 μm. Next, short fibers are attached to the adhesive layer to form flocked layers 9 ', 29', 39 'to which the solid lubricant and the short fibers are fixed.

  Examples of the method for forming the adhesive layer include a method in which an adhesive is applied by a spray method, a dip method, or the like. Before forming the adhesive layer, the surface may be subjected to a pretreatment such as a cleaning treatment such as alcohol wiping or a primer treatment.

  Examples of the adhesive include RFL liquid, urethane emulsion, acrylic emulsion, vinyl acetate emulsion, styrene emulsion, rubber adhesive, and organic solvent adhesive. The RFL liquid is obtained by mixing an initial condensate of resorcin and formaldehyde in a latex. Examples of the latex used here include chloroprene, styrene-butadiene-vinylpyridine terpolymer, hydrogenated nitrile, NBR, ethylene. α-olefin / diene copolymer rubber latex. Further, an isocyanate compound can be added to the RFL liquid.

  The adhesive contains 20 to 70% by weight of a solid lubricant. If it is less than 20% by weight, a sufficient friction coefficient reduction effect cannot be achieved, and if it exceeds 70% by weight, it becomes difficult to fix short fibers, and a flocking layer having a uniform flocking density cannot be obtained. There is. As the solid lubricant, those mentioned above can be used.

  The thickness of the adhesive layer is not particularly limited, but is 0.05 to 0.5 mm, preferably 0.05 mm to 0.3 mm.

  The method for attaching the short fibers is not limited to a mechanical or electrostatic method. For example, the short fibers are adhered to the rubber surface by dropping or spraying the short fibers on the rubber sheet on which the adhesive layer is formed, and then natural or heat drying is performed. Also, for example, a short fiber in which a metal mold having a rubber sheet on which an adhesive layer is formed is grounded, an electric field is formed by applying a voltage to an electrode of an electrostatic flocking machine, and the surface is electrodeposited in the electric field , Fly and stick to the rubber surface to attach the short fibers, and then perform natural or heat drying. In consideration of density and uniformity, electrostatic flocking is desirable.

  As another method for forming a compression part having a flocking layer, there is a method using a method in which short fibers are attached to a mold that contacts a compressed rubber sheet. For example, in the first method, an inner mold in which short fibers are attached to the outer peripheral surface is prepared, and an unvulcanized compressed rubber sheet having an adhesive layer to which a solid lubricant is fixed is adhered to the inner mold. Can be achieved. In the second and third methods, an outer mold having short fibers attached to the inner peripheral surface is prepared, and an unvulcanized structure in which a compressed rubber layer having an adhesive layer with a solid lubricant fixed is arranged on the outermost layer. This can be achieved by bringing the sleeve into contact with the outer mold. The specific method for preparing these molds is to apply a release agent such as silicone oil to the peripheral surface of the mold, then form an adhesive layer by the method described above, and then drop or spray the short fibers. A mold having the short fibers attached to the peripheral surface can be prepared by attaching them by charging, or by charging the mold and flying the short fibers with electric lines of force.

  Then, by vulcanizing the unvulcanized belt sleeve provided with the flocking layers 9 ′, 29 ′, 39 ′, the solid lubricant and the short fibers remain adhered to the rubber surface (in some cases, the rubber is partially or The flocked layers 9, 29, 39 are formed (mostly embedded and fixed), and a vulcanized belt sleeve in which the flocked layers 9, 29, 39 are disposed is formed.

  Hereinafter, the present invention will be described with specific examples.

<Production of V-ribbed belt>
In the V-ribbed belt produced in this example, a cord made of polyester fiber cord is embedded in the belt body, the back surface (extension portion) is formed of a rubber layer, and three compression portions are provided on the other surface side. The rib portion is arranged in the longitudinal direction of the belt. The stretched portion contains short fibers, and the short fibers are oriented in a random direction.

  The compressed rubber sheet used in the manufacturing method of the V-ribbed belt was prepared by preparing a rubber composition according to the composition shown in Table 1, kneading with a Banbury mixer, and rolling with a calendar roll. The compression rubber sheet is formed by forming an adhesive layer using an adhesive, and then forming a flocked layer by electrostatically flocking cotton short fibers (fiber length 0.5 mm). Table 2 shows the PTFE content. Also, a rubber composition in which 10 parts by weight of nylon milled fiber (fiber length 2 mm) is blended with 100 parts by weight of rubber in the composition shown in Table 1 is prepared, kneaded with a Banbury mixer, rolled with a calender roll, and stretched rubber. A sheet was produced.

  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 obtained vulcanized belt sleeve is cut into individual belts by a cutter. Thus, a V-ribbed belt was obtained.

  Using the obtained V-ribbed belt, sound resistance, friction, wear resistance, and durability were evaluated. The evaluation test method is shown below.

◎ Abrasion test The running test machine used for the evaluation of the abrasion test was configured by arranging 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) in this order. Is. 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 driving pulley under the test conditions of a rotation speed of 4900 rpm and a belt tension of 57 kgf / 3 rib, a load 12 PS was applied to the driven pulley, and the V-ribbed belt was run for 150 hours, and then 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. The results are also shown in Table 2.

◎ High-temperature low-tension reverse bending test The running test machine used for the evaluation of the heat resistance durability test is a driving pulley (diameter 120 mm), idler pulley (diameter 85 mm), driven pulley (diameter 120 mm), tension pulley (diameter 45 mm) in this order. It is arranged and configured. 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 is applied to the drive pulley under the test conditions of a rotation speed of 4900 rpm and a belt tension of 57 kgf / 3 rib, and a load 12 PS is applied to the driven pulley to run the V-ribbed belt. The running time was discontinued at 400 hours, and the time until six cracks reaching the core line occurred was examined. The results are also shown in Table 2.

Misalignment sound generation test The testing machine used for the evaluation was configured by arranging a driving pulley (diameter 120 mm), a driven pulley (diameter 120 mm), and a tension pulley (diameter 70 mm). Here, a misalignment of 1.86 ° was set between the driving pulley and the driven pulley. A V-ribbed belt is hung on each pulley of the test machine, and the load is applied to the drive pulley so that the rotation speed of the drive pulley is 1000 rpm and the belt tension is 6 kgf / rib at room temperature. .Evaluation of the sound level when running with 1Nm / rib added. The sound generation level is evaluated in five stages, and “5” indicates a state where the sound generation level is the lowest. Note that “3” or higher was defined as a level at which pronunciation is not a concern. This test was carried out on the belt before and after the wear test, and evaluated during drying (DRY) and at the time of water injection (WET) at 60 cc / min. The results are shown in Table 2.
5: I can't hear anything.
4: Can be heard with a stethoscope.
3: Sounds faint.
2: I can hear it.
1: Sounds clear.

Friction test In the friction test, a V-ribbed belt is hung on a guide roller (diameter 60 mm) so that the winding angle of the V-ribbed belt is 90 °, one end of the V-ribbed belt is fixed, and the other end is 1.75 kgf / 3. By detecting the value of the load cell when the weight of the rib is suspended and the guide 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. This test was carried out on the belt before and after the wear test, and evaluated during drying (DRY) and at the time of water injection (WET) at 60 cc / min. The results are shown in Table 2.

  From the results shown in Table 2, it was found that the wear resistance and durability were not impaired in any of the examples, and that excellent friction characteristics and sound resistance were exhibited. On the other hand, although the comparative example 1 had high durability like the Example, the friction coefficient at the time of DRY was high and the difference of the friction coefficient at the time of WET was large. Further, in the sound generation test, there was an abnormal sound at both DRY and WET, and the wear resistance was not sufficient. In Comparative Example 2, there was no problem with respect to the friction characteristics and the sound resistance, but cracks occurred early in the durability test, and the durability was not satisfactory and the wear resistance was also difficult.

  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 the 1st Embodiment of this invention. It is sectional drawing of the V-ribbed belt which is the 2nd Embodiment of this invention. It is sectional drawing of the V-ribbed belt which is the 3rd Embodiment of this invention.

Explanation of symbols

1 V-ribbed belt (friction drive belt)
3 Core wire 2 Bonding part 5 Extension part 6 Compression part (friction transmission part)
9 Flocking layer 9a Solid lubricant 9b Short fiber

Claims (3)

  An adhesive layer is formed on the unvulcanized rubber constituting the friction transmission surface using an adhesive containing 20 to 70% by weight of a solid lubricant having an average primary particle size of 0.15 to 20 μm. A method for producing a friction transmission belt, comprising forming a flock layer in which a solid lubricant and a short fiber are fixed on a friction transmission surface by fixing vulcanized fibers and then vulcanizing.   The method for producing a friction transmission belt according to claim 1, wherein the solid lubricant is polytetrafluoroethylene. The method of manufacturing a friction transmission belt according to claim 1 or 2, wherein the friction transmission belt is a V-ribbed belt.

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