JP6423321B2 - V-ribbed belt and manufacturing method thereof - Google Patents

Description

  The present invention relates to a V-ribbed belt used for driving an automobile engine accessory and the like, and more particularly, to a V-ribbed belt capable of reducing the amount of grinding in a method of forming a rib portion by grinding and having excellent appearance and durability, and a method for manufacturing the same. .

  In the rubber industry field, high functionality and high performance are desired especially for automobile parts. One of the rubber products used for such automobile parts is a V-ribbed belt having ribs provided along the longitudinal direction of the belt. The V-ribbed belt is, for example, an auxiliary drive such as an automobile air compressor or alternator. Widely used for power transmission.

  As a manufacturing method of a V-ribbed belt, a manufacturing method is known in which a rib portion (compressed rubber layer) having an inverted trapezoidal cross section is formed by grinding. Specifically, in the manufacturing process of the V-ribbed belt, first, a belt sleeve is formed by winding each molded member (cover cloth, unvulcanized rubber sheet, core wire, etc.) around the outer peripheral surface of a cylindrical mold. Normally, the belt sleeve is formed such that the grinding surface (compressed rubber layer forming the rib) is on the outer peripheral side and the belt rear surface is on the inner peripheral side. Next, vulcanization is performed by placing the belt sleeve in a vulcanizing can with the vulcanization jacket placed on the outer peripheral side of the belt sleeve. In vulcanization of the belt sleeve, vulcanization is performed in a state where the outer peripheral surface of the belt sleeve and the inner peripheral surface of the vulcanization jacket are in contact with each other, and the vulcanization jacket is removed (released) after vulcanization. Further, ventilation (air venting) is necessary so that air (bubbles) does not accumulate in the belt sleeve during vulcanization. In order to ensure this mold release and air permeability (air bleeding), a thick non-woven fabric is wound around the outer peripheral surface of the sleeve and vulcanized, and after release, the non-woven fabric is ground together with the ground portion of the compressed rubber. A removal method (a method of grinding the entire rib portion) is employed.

  In recent years, efforts have been made to reduce material costs by reducing grinding amount (waste rubber amount) and belt thickness from the viewpoint of cost reduction. To reduce the amount of grinding (waste rubber), the entire rib is not ground, but the tip of the rib (the bottom of the inverted trapezoid) is not ground but only the V groove (only the side) is ground. In this construction method, since the outer peripheral surface of the vulcanization sleeve becomes the rib tip surface as it is, if a non-woven fabric is used on the outer peripheral surface, the nonwoven fabric remains on the tip surface (rib tip surface) of the rib portion.

  As a V-ribbed belt having a nonwoven fabric on the rib front end surface, for example, Japanese Patent Application Laid-Open No. 2005-69358 (Patent Document 1) does not use short fiber-containing rubber and generates abnormal noise with a pulley. In order to suppress wear on the belt surface, it has been proposed that the rib rubber layer has a structure in which rubber layers and nonwoven fabric layers are alternately laminated in the belt thickness direction. A V-ribbed belt is disclosed.

  However, in a V-ribbed belt having a nonwoven fabric on the rib front end surface, the appearance of the nonwoven fabric surface is deteriorated and the belt bendability is lowered during belt running (the nonwoven fabric is stretched and hinders bending). ), Durability is reduced (cracks are easily generated). On the other hand, if the nonwoven fabric is not used, the releasability and air permeability (air bleeding) become insufficient, and the surface property of the vulcanized jacket is transferred to the sleeve surface (rib tip surface). In the case of a vulcanized jacket with scratches, the scratches are transferred and the appearance is deteriorated.

  Japanese Patent Application Publication No. 2005-533983 (Patent Document 2) discloses a V-ribbed belt having a thermoplastic resin layer (a layer of a film rather than a fiber) on the end surface of the rib. This document describes that after a thermoplastic resin layer is bonded to a rib, the belt is cut and cut into a V-belt shape.

  However, even with this V-ribbed belt, the air permeability (air bleeding) is insufficient, and the bendability of the belt is lowered (the thermoplastic resin layer is stretched to prevent bending), and the durability is lowered (cracking). Easier to enter).

Japanese Patent Laying-Open No. 2005-69358 (Claim 1, paragraphs [0012] and [0019], FIG. 4A) JP-T-2005-533983 gazette (Claim 1, paragraphs [0018] [0019])

  Accordingly, an object of the present invention is to provide a V-ribbed belt that can be formed by grinding a rib portion with a small amount of grinding (amount of waste rubber) and that can smoothly proceed with a vulcanization process, and a method for manufacturing the same.

  Another object of the present invention is to provide a V-ribbed belt that is excellent in appearance and can improve durability such as crack resistance and heat resistance, and a method for producing the same.

  Still another object of the present invention is to provide a V-ribbed belt that does not require an adhesive treatment of a nonwoven fabric and can improve winding workability even if it contains fibers, and a method for manufacturing the same.

  As a result of intensive studies to achieve the above-mentioned problems, the present inventors have found that the bottom portion of the compressed rubber layer of the V-ribbed belt is a ground surface in which the side portion is in contact with the pulley and the bottom portion is a non-ground surface that is not in contact with the pulley. The surface is formed of a fibrous portion that contains thermoplastic fibers that melt at the vulcanization temperature of the rubber composition that constitutes the compressed rubber layer, and the fibrous shape remains, and a non-fibrous portion that has lost its fibrous shape. Ribs can be formed by grinding with a small amount of grinding (amount of waste rubber), and the vulcanization process proceeds smoothly by using a composite layer containing a heat-treated non-woven fabric and a vulcanized product of the rubber composition. I found what I could do and completed the present invention.

That is, the V-ribbed belt of the present invention includes a compressed rubber layer containing a vulcanizate of a rubber composition, a core wire, and an extension layer, and a side surface of the compressed rubber layer is a ground surface that contacts a pulley, and A V-ribbed belt that is a non-ground surface in which the bottom of the compressed rubber layer does not come into contact with the pulley, and the heat treated product of the nonwoven fabric containing the thermoplastic fiber that melts at the vulcanization temperature of the rubber composition, A composite layer containing a vulcanized product of the rubber composition, and the heat-treated product of the nonwoven fabric is formed of a fibrous portion in which the fiber shape remains and a non-fibrous portion in which the fiber shape has disappeared. The thermoplastic fibers may be at least one selected from the group consisting of polyolefin fibers and polyurethane fibers (particularly polypropylene fibers). The basis weight of the nonwoven fabric is about 12 to 30 g / m ² . The average thickness of the nonwoven fabric is about 0.03 to 0.3 mm. The fibers of the nonwoven fabric may be oriented in a predetermined direction, and the longitudinal direction of the fibers may be parallel to the longitudinal direction of the belt. The compressed rubber layer may have a rib portion, and the average thickness of the rib portion may be 54% or less with respect to the average thickness of the entire V-ribbed belt.

  The present invention includes a stretch layer mounting step for mounting a stretch layer member for forming a stretch layer on a cylindrical drum, a core spinning step for winding a core wire, and an unvulcanized for forming a compressed rubber layer Compressed rubber layer winding step for winding a rubber sheet, a non-woven fabric winding step for winding a non-woven fabric containing a thermoplastic fiber on the wound unvulcanized rubber sheet, the stretch layer member, the core wire, and an unvulcanized rubber sheet And a vulcanization step of vulcanizing the nonwoven fabric at a temperature higher than the melting point of the thermoplastic fiber to obtain a vulcanized sleeve, and a grinding step of grinding only the side portion of the compressed rubber layer on the nonwoven fabric side of the vulcanized sleeve The manufacturing method of the said V ribbed belt containing is also included. The vulcanization temperature may be 5 to 15 ° C. higher than the melting point of the thermoplastic fiber.

  In the present invention, the rubber composition in which the surface of the bottom portion of the compressed rubber layer of the V-ribbed belt whose side portion is a ground surface in contact with the pulley and whose bottom portion is a non-ground surface not in contact with the pulley constitutes the compressed rubber layer. A non-fibrous heat-treated product formed of a fibrous part containing thermoplastic fibers that melt at a vulcanization temperature and having a fiber shape remaining, and a non-fibrous part that has lost the fiber shape; Because it is a composite layer containing a sulfide, it is not necessary to grind the bottom of the compressed rubber layer, and ribs can be formed by grinding with a small amount of grinding (amount of waste rubber). Since releasability and air permeability can be ensured, air venting during vulcanization and release from the vulcanization jacket can proceed smoothly. Therefore, transfer of scratches and spots on the vulcanization jacket can be suppressed, and the nonwoven fabric partially melts in the vulcanization process, so that the fibers of the nonwoven fabric can be prevented from fuzzing and the appearance can be improved. Furthermore, since the nonwoven fabric and the compressed rubber layer are integrated by vulcanization, the adhesive treatment of the nonwoven fabric is unnecessary, and the longitudinal direction of the fibers constituting the nonwoven fabric is made parallel to the longitudinal direction of the belt, thereby including the fibers. Even in this case, stretching and breakage can be suppressed when pulled in the winding direction (circumferential direction), and belt winding workability can be improved.

FIG. 1 is a schematic sectional view showing an example of the V-ribbed belt of the present invention. FIG. 2 is a layout of a testing machine used in the bending fatigue resistance (crack resistance) test in the examples. FIG. 3 is a surface electron micrograph of the composite layer of the V-ribbed belt obtained in Example 2. 4 is a cross-sectional electron micrograph of the composite layer of the V-ribbed belt obtained in Example 2. FIG. FIG. 5 is a photograph of the rib portion of the V-ribbed belt obtained in Example 2. 6 is a photograph of the rib portion of the V-ribbed belt obtained in Reference Example 1. FIG.

  The V-ribbed belt of the present invention is provided with a compressed rubber layer having a substantially inverted trapezoidal cross section by grinding and containing a vulcanizate of a rubber composition, and the side of the compressed rubber layer is in contact with a pulley. And a non-ground surface where the bottom of the compressed rubber layer does not contact the pulley.

  The form of the V-ribbed belt is not particularly limited as long as it has such a compressed rubber layer. For example, the form shown in FIG. 1 is exemplified. FIG. 1 is a schematic cross-sectional view showing an example of a V-ribbed belt of the present invention. In this configuration, an extension layer 1 composed of an outer fabric (woven fabric, knitted fabric, nonwoven fabric, etc.) and a core wire 2 are embedded in the longitudinal direction of the belt in order from the belt upper surface (back surface) to the belt lower surface (inner circumferential surface). The adhesive rubber layer 3 and the compressed rubber layer 4 are laminated. A plurality of V-shaped grooves extending in the longitudinal direction of the belt are formed in the compressed rubber layer 4, and a V-shaped cross section [reverse trapezoidal shape (a trapezoidal shape that tapers toward the tip of the rib) is formed between the grooves. )] Are formed (two in the example shown in FIG. 1), and the two inclined surfaces (surfaces) of each rib portion form a friction transmission surface, and contact the pulley to transmit power (friction). Transmission). In particular, in the present invention, the side surface (inclined surface) of the rib portion is the ground surface 4a, and the bottom surface of the rib portion is the non-ground surface composite layer 5.

  The V-ribbed belt of the present invention is not limited to this form, and may be provided with such a compressed rubber layer. For example, the stretch layer may be formed of a rubber composition, and the stretch layer may be formed without providing an adhesive rubber layer. A cord may be buried between the rubber layer and the compressed rubber layer. Further, an adhesive rubber layer is provided on either the compressed rubber layer or the stretched layer, and the core wire is provided between the adhesive rubber layer (compressed rubber layer side) and the stretched layer, or the adhesive rubber layer (stretched layer side) and the compressed rubber. It may be embedded in between the layers.

[Composite layer]
The composite layer is formed at the bottom of the compressed rubber layer without being ground, and is a non-ground heat-treated product containing thermoplastic fibers that melt at the vulcanization temperature of the rubber composition constituting the compressed rubber layer. Including vulcanizates.

(Nonwoven fabric heat treatment)
The heat-treated product of the nonwoven fabric is formed of a fibrous portion in which the fiber shape remains and a non-fibrous portion in which the fiber shape has disappeared. Therefore, the composite layer forms a structure in which three components, a fibrous part, a non-fibrous part, and a rubber component, are mixed appropriately, and the remaining fiber shape allows for releasability and breathability in the vulcanization process, as well as durability. Can be ensured, and the appearance of the belt can be improved by the non-fiber shape generated by melting.

  The shape of the fibrous portion is the shape of the fibers constituting the nonwoven fabric before heat treatment. An average fiber diameter is 1-150 micrometers, for example, Preferably it is 5-100 micrometers, More preferably, it is about 10-50 micrometers (especially 20-40 micrometers). The average fiber length is not particularly limited, and may be a long fiber.

  The shape of the non-fibrous portion is not particularly limited as long as the fiber shape has disappeared, and is usually a film shape or a lump shape. Of these, a non-film shape, for example, a lump shape such as an indefinite shape or a granular shape, is preferred because the rib tip is in a stretched state and the belt can be prevented from being lowered in flexibility.

  In the composite layer, the volume ratio between the fibrous portion and the non-fibrous portion is, for example, the former / the latter = 9/1 to 1/9, preferably 8/2 to 2/8, more preferably 7/3 to 3 / 7. If the proportion of the fibrous portion is too small, the releasability and breathability in the vulcanization process may be lowered, and the durability of the belt is lowered (bending the non-fibrous portion to prevent bending). There is a fear. On the other hand, if the amount is too large, the appearance of the belt may be deteriorated (fibrous portions become conspicuous and noticeable).

  The existence form of the fibrous part and the non-fibrous part in the composite layer is sufficient if at least a part of the fibrous part is present on the surface of the composite layer in order to ensure the releasability and air permeability in the vulcanization process. Other fibrous parts and non-fibrous parts may be embedded in the composite layer. Moreover, it is preferable that a part of the fibrous portion is embedded in the composite layer, and the appearance and durability of the belt can be improved by embedding a part of the fiber in which the fiber shape remains in the rubber composition. Furthermore, it is preferable that part or all of the non-fibrous part is embedded in the composite layer, and the non-fibrous part is formed into a film on the surface of the composite layer by embedding the non-fibrous part in the composite layer. It is possible to suppress a decrease in the bending resistance of the belt that occurs in some cases.

The basis weight of the nonwoven fabric before the heat treatment can be selected from a range of about 10 to 50 g / m ² , for example, 12 to 30 g / m ² , preferably 13 to 28 g / m ² , and more preferably about 15 to 25 g / m ^2. . The average thickness of the nonwoven fabric before heat treatment is, for example, 0.03 to 0.3 mm, preferably 0.12 to 0.27 mm, more preferably 0.14 to 0.25 mm (particularly about 0.14 to 0.23 mm). If the fabric weight or thickness of the nonwoven fabric is too small, there is a risk that the releasability and breathability in the vulcanization process may be reduced, and the nonwoven fabric is torn when it is molded (wrapping of each member before vulcanization). On the other hand, if the fabric weight or thickness of the nonwoven fabric is too large, the gap between the fibers becomes small, so that the rubber component is difficult to enter between the fibers, and the fiber form is easily lost by melting, There is a possibility that the resin constituting the non-woven fabric alone becomes a film on the surface of the composite layer, and the non-woven fabric becomes rigid and may be difficult to wind.

  The fiber constituting the nonwoven fabric may be any thermoplastic fiber that melts at the vulcanization temperature of the rubber composition constituting the compressed rubber layer. For example, polyolefin fiber, acrylic fiber, vinyl fiber, styrene fiber, polycarbonate fiber Examples thereof include fibers, polyurethane fibers, and thermoplastic elastomer fibers. These thermoplastic fibers can be used alone or in combination of two or more. Of these thermoplastic fibers, polyolefin fibers and / or polyurethane fibers (polyester-type polyurethane fibers, polyether-type polyurethane fibers, etc.) are preferable, and polyolefin fibers are particularly preferable because of excellent versatility.

The olefin resin constituting the polyolefin fiber is an α-olefin such as ethylene, propylene, 1-butene, 1-pentene, 1-hexene, 3-methylpentene, 4-methylpentene (particularly α-olefin such as ethylene, propylene, etc.). A polymer having C _2-6 olefin) as a main polymerization component may be used. Examples of the copolymerizable monomer other than the α-olefin include (meth) acrylic monomers [for example, (meth) acrylic acid C ₁ such as methyl (meth) acrylate and ethyl (meth) acrylate. _-6 alkyl ester etc.], unsaturated carboxylic acids (eg maleic anhydride etc.), vinyl esters (eg vinyl acetate, vinyl propionate etc.), dienes (butadiene, isoprene etc.) and the like. These monomers can be used alone or in combination of two or more.

  Examples of olefin resins include polyethylene resins [low, medium or high density polyethylene, linear low density polyethylene, ethylene-propylene copolymer, ethylene-butene-1 copolymer, ethylene-propylene-butene-1]. Copolymer, ethylene- (4-methylpentene-1) copolymer, etc.], polypropylene resin (polypropylene, propylene-ethylene copolymer, propylene-butene-1 copolymer, propylene-ethylene-butene-1 copolymer) Polymer) and the like. The melting point of the olefin resin may be controlled by copolymerizing a copolymerizable monomer at a specific ratio. For example, ethylene may be copolymerized with a polypropylene resin to lower the melting point. These olefin resins can be used alone or in combination of two or more.

  Of these olefin resins, polyethylene resins such as polyethylene and polypropylene resins such as polypropylene are preferable. From the viewpoint of easy melting at the vulcanization temperature and excellent heat resistance, polypropylene such as polypropylene is preferable. A resin is particularly preferred.

  The nonwoven fabric (or the fibers constituting the nonwoven fabric) may be prepared by using conventional additives such as reinforcing agents, fillers, metal oxides, plasticizers, processing agents or processing aids, coloring agents, coupling agents, if necessary. Stabilizers (ultraviolet absorbers, antioxidants, ozone deterioration inhibitors, thermal stabilizers, etc.), lubricants, flame retardants, antistatic agents, and the like may be included. The ratio of the additive is about 10% by weight or less (for example, 0.1 to 5% by weight) with respect to the entire nonwoven fabric.

  The melting point of the thermoplastic fiber may be equal to or lower than the vulcanization temperature of the rubber composition, and is, for example, about 100 to 180 ° C, preferably about 110 to 170 ° C, and more preferably about 160 to 170 ° C. If the melting point is too high, the proportion of the non-fibrous portion may be reduced, and conversely if it is too low, the proportion of the fibrous portion may be reduced.

  The fibers constituting the nonwoven fabric may be randomly oriented, but are oriented in a predetermined direction [such as the flow direction (MD) direction in the manufacturing process] from the viewpoint of improving the strength in a specific direction. preferable. Nonwoven fabrics with fibers oriented in a given direction can suppress elongation and breakage when pulled in the winding direction (circumferential direction) by making the longitudinal direction of the fibers parallel to the longitudinal direction of the belt, and the belt winding workability Can be improved.

(Vulcanized rubber composition)
In the present invention, a flexible composite layer is formed by forming a three-component system in which the heat-treated product of the nonwoven fabric and the vulcanized product of the rubber composition are mixed appropriately, and this is an obstacle (stretching) in the bending of the belt. Therefore, the durability of the belt can be improved.

  The rubber composition is a rubber composition in which the rubber composition of the compressed rubber layer has penetrated between the fibers of the nonwoven fabric. The rubber composition is not particularly limited, but usually a rubber composition containing a rubber component and a vulcanizing agent or a crosslinking agent is used. In particular, the present invention forms an unvulcanized rubber layer from a rubber composition containing sulfur or an organic peroxide (particularly an organic peroxide vulcanized rubber composition), and vulcanizes or crosslinks the unvulcanized rubber layer. Useful to do.

  Examples of rubber components include vulcanizable or crosslinkable rubbers such as diene rubbers (natural rubber, isoprene rubber, butadiene rubber, chloroprene rubber, styrene butadiene rubber (SBR), acrylonitrile butadiene rubber (nitrile rubber), and hydrogenated nitrile rubber. , Mixed polymers of hydrogenated nitrile rubber and unsaturated carboxylic acid metal salt, etc.), ethylene-α-olefin elastomer, chlorosulfonated polyethylene rubber, alkylated chlorosulfonated polyethylene rubber, epichlorohydrin rubber, acrylic rubber, silicone rubber, Examples thereof include urethane rubber and fluorine rubber. These rubber components can be used alone or in combination of two or more.

  Of these, ethylene-α-olefin elastomers (ethylene-α-olefin rubbers) are preferred because they do not contain harmful halogens, have ozone resistance, heat resistance, cold resistance, and are excellent in economic efficiency. Furthermore, since the ethylene-α-olefin elastomer has low water wettability compared to other rubbers, it can significantly improve power transmission and quietness during water injection.

  Examples of the ethylene-α-olefin elastomer (ethylene-α-olefin rubber) include ethylene-α-olefin rubber and ethylene-α-olefin-diene rubber.

Examples of the α-olefin include chain α-C _3-12 olefins such as propylene, butene, pentene, methylpentene, hexene, and octene. The α-olefin can be used alone or in combination of two or more. Of these α-olefins, α-C _3-4 olefins (particularly propylene) such as propylene are preferred.

  Examples of the diene monomer usually include non-conjugated diene monomers such as dicyclopentadiene, methylene norbornene, ethylidene norbornene, 1,4-hexadiene, and cyclooctadiene. These diene monomers can be used alone or in combination of two or more.

  Typical ethylene-α-olefin elastomers include, for example, ethylene-α-olefin rubber (ethylene-propylene rubber (EPR)), ethylene-α-olefin-diene rubber (ethylene-propylene-diene copolymer (EPDM, etc.)). And the like. A preferred ethylene-α-olefin elastomer is EPDM.

  In the ethylene-α-olefin rubber, the ratio (mass ratio) of ethylene and α-olefin is the former / the latter = 40/60 to 90/10, preferably 45/55 to 85/15 (for example, 50/50 to 82/18), more preferably 55/45 to 80/20 (for example, 55/45 to 75/25). Moreover, the ratio of the diene can be selected from the range of about 4 to 15% by mass with respect to the whole rubber, for example, 4.2 to 13% by mass (for example, 4.3 to 12% by mass), preferably 4.4. About 11.5 mass% (for example, 4.5-11 mass%) may be sufficient. The iodine value of the ethylene-α-olefin rubber containing the diene component may be, for example, about 3 to 40 (preferably 5 to 30, more preferably 10 to 20). If the iodine value is too small, vulcanization of the rubber composition will be insufficient and wear and adhesion will easily occur, and if the iodine value is too large, the scorch of the rubber composition will become short and difficult to handle, and it will be heat resistant. Tends to decrease.

  As the organic peroxide, organic peroxides usually used for crosslinking of rubber and resin, for example, diacyl peroxide, peroxy ester, dialkyl peroxide (for example, dicumyl peroxide, t-butyl cumyl peroxide) are used. Oxide, 1,1-di-butylperoxy-3,3,5-trimethylcyclohexane, 2,5-dimethyl-2,5-di (t-butylperoxy) -hexane, 1,3-bis (t- Butylperoxy-isopropyl) benzene, di-t-butyl peroxide, etc.). These organic peroxides can be used alone or in combination of two or more. Further, the organic peroxide is preferably a peroxide having a half-life of about 150 to 250 ° C. (for example, 175 to 225 ° C.) by thermal decomposition.

  The ratio of the vulcanizing agent or the crosslinking agent (especially organic peroxide) is 1 to 10 parts by mass, preferably 1 in terms of solid content with respect to 100 parts by mass of the rubber component (such as ethylene-α-olefin elastomer). It is 2-8 mass parts, More preferably, it is about 1.5-6 mass parts (for example, 2-5 mass parts).

  The rubber composition may further contain a vulcanization accelerator. Examples of the vulcanization accelerator include thiuram accelerators, thiazol accelerators, sulfenamide accelerators, bismaleimide accelerators, urea accelerators, and the like. These vulcanization accelerators can be used alone or in combination of two or more. The proportion of the vulcanization accelerator is, for example, 0.5 to 15 parts by mass, preferably 1 to 10 parts by mass, and more preferably about 2 to 5 parts by mass in terms of solid content with respect to 100 parts by mass of the rubber component. is there.

  The rubber composition may further contain a co-crosslinking agent (crosslinking aid or co-vulcanizing agent) in order to increase the degree of crosslinking and prevent adhesive wear and the like. Examples of co-crosslinking agents include conventional crosslinking aids such as polyfunctional (iso) cyanurates [eg, triallyl isocyanurate (TAIC), triallyl cyanurate (TAC), etc.], polydienes (eg, 1,2-polybutadiene). Etc.), metal salts of unsaturated carboxylic acids [eg, zinc (meth) acrylate, magnesium (meth) acrylate, etc.], oximes (eg, quinone dioxime), guanidines (eg, diphenyl guanidine, etc.), Multifunctional (meth) acrylate [for example, ethylene glycol di (meth) acrylate, butanediol di (meth) acrylate, trimethylolpropane tri (meth) acrylate, etc.], bismaleimides (N-N'-m-phenylenebismaleimide Etc.). These crosslinking aids can be used alone or in combination of two or more. The ratio of the crosslinking aid (the total amount when a plurality of types are combined) is, for example, 0.01 to 10 parts by mass, preferably 0.05 to 8 parts by mass with respect to 100 parts by mass of rubber, in terms of solid content. Preferably it is about 0.1-5 mass parts.

  If necessary, the rubber composition may be prepared by adding conventional additives such as a vulcanization aid, a vulcanization accelerator, a vulcanization retarder, a reinforcing agent (carbon oxide, silicon oxide such as hydrous silica), a filler ( Clay, calcium carbonate, talc, mica, etc.), reinforcing fibers (polyamide short fibers such as aramid short fibers, polyester short fibers, vinylon short fibers), metal oxides (eg, zinc oxide, magnesium oxide, calcium oxide, barium oxide) , Iron oxide, copper oxide, titanium oxide, aluminum oxide, etc.), softener (oils such as paraffin oil, naphthenic oil, process oil), processing agent or processing aid (stearic acid, metal stearate, wax) , Paraffin, fatty acid amide, etc.), anti-aging agent (antioxidant, thermal anti-aging agent, anti-bending material, anti-ozone degradation agent) Etc.), coloring agents, tackifiers, plasticizers, coupling agents (such as silane coupling agents), stabilizers (such as UV absorbers, antioxidants, ozone degradation inhibitors, thermal stabilizers), lubricants, difficult A flame retardant, an antistatic agent, etc. may be included. The metal oxide may act as a crosslinking agent. These additives can be used alone or in combination of two or more.

  The proportion of these additives can be selected from a conventional range depending on the type. For example, the proportion of the reinforcing agent (carbon black, silica, etc.) is 10 to 200 parts by mass (particularly 20 to 200 parts by mass with respect to 100 parts by mass of the rubber component). 150 parts by mass), the proportion of reinforcing fibers may be about 80 parts by mass or less (for example, 1 to 60 parts by mass), and the proportion of metal oxide (such as zinc oxide) is 1 to 15 parts by mass. Part (especially 2 to 10 parts by mass), and the proportion of softener (oils such as paraffin oil) may be about 1 to 30 parts by mass (particularly 5 to 25 parts by mass). About 0.1-5 mass parts (especially 0.5-3 mass parts) may be sufficient as the ratio of an agent (stearic acid etc.).

(Thickness of composite layer)
The average thickness of the composite layer is, for example, about 0.02 to 0.15 mm, preferably about 0.03 to 0.1 mm. The average thickness of the composite layer can be measured on the basis of a non-woven fabric heat-treated product embedded in the compressed rubber layer, and can be measured by measuring the embedded depth at any 10 locations on the bottom surface of the compressed rubber layer and determining the average value. .

[Other layers and cores]
The compressed rubber layer is formed of the same rubber composition as the rubber composition contained in the composite layer. The average thickness of the compressed rubber layer is, for example, about 2 to 20 mm, preferably about 2.5 to 15 mm, and more preferably about 3 to 10 mm.

  The same rubber composition as the compressed rubber layer (a rubber composition containing a rubber component such as an ethylene-α-olefin elastomer) can be used for the adhesive rubber layer. In the rubber composition of the adhesive rubber layer, as the rubber component, the same type or the same type of rubber as the rubber component of the rubber composition of the compressed rubber layer is often used. Further, the ratio of additives such as a vulcanizing agent or a crosslinking agent, a co-crosslinking agent or a crosslinking aid, and a vulcanization accelerator can be selected from the same range as that of the rubber composition of the compressed rubber layer. The rubber composition of the adhesive rubber layer may further contain an adhesion improver (resorcin-formaldehyde cocondensate, amino resin, etc.). The average thickness of the adhesive rubber layer is, for example, about 0.4 to 3 mm, preferably about 0.6 to 2 mm, and more preferably about 0.8 to 1.5 mm.

  For the core wire, high modulus fibers such as polyester fibers (polyalkylene arylate fibers), synthetic fibers such as aramid fibers, and inorganic fibers such as carbon fibers are widely used. Polyester fibers (polyethylene terephthalate fibers, polyethylene naphthalates) System fibers) and aramid fibers are preferred. The fiber may be a multifilament yarn, for example, a multifilament yarn having a fineness of 2000 to 10000 denier (particularly 4000 to 8000 denier).

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

  In order to improve the adhesion to the polymer component, the core wire is embedded between the stretched layer and the compressed rubber layer (especially the adhesive rubber layer) after various adhesive treatments with epoxy compounds, isocyanate compounds, etc. Also good.

  When the stretch layer is formed of a cover cloth, the cover cloth may be a cloth material (preferably a woven cloth) such as a woven cloth, a wide-angle sail cloth, a knitted cloth, and a non-woven cloth. When the stretch layer is formed of a rubber composition, the rubber composition constituting the stretch layer may be formed of a rubber composition that forms a compressed rubber layer. The thickness of the stretch layer is, for example, about 0.8 to 10 mm, preferably about 1.2 to 6 mm, and more preferably about 1.6 to 5 mm.

[V-ribbed belt and manufacturing method thereof]
The average thickness of the V-ribbed belt of the present invention can be selected from the range of about 2 to 12 mm, for example, 2.5 to 10 mm, preferably about 3.8 to 5 mm, for example about 4.1 to 4.3 mm. Also good. The average thickness of the rib portion can be selected from a range of about 1 to 3.5 mm, for example, 1.2 to 3 mm, preferably 1.5 to 2.7 mm, and more preferably about 1.6 to 2 mm. The average thickness of the rib portion may be 54% or less with respect to the average thickness of the entire belt, and is preferably about 36 to 53%.

  In the present invention, since the bottom surface of the rib portion is a composite layer and the belt has excellent durability, the thickness of the rib portion can be reduced. For example, when the conventional product has a belt thickness of 4.3 ± 0.3 mm and a rib height of 2.0 ± 0.2 mm, by reducing the rib height by 0.2 mm (2.0 → 1.8 mm), the belt The thickness can be reduced to 4.1 ± 0.3 mm. Since the rib height can be reduced and the grinding allowance (grinding for the bottom portion of the rib portion) that has been conventionally required is unnecessary, the amount of the rubber composition constituting the belt can be reduced. Further, since the amount of grinding is reduced, grinding time and grinding waste can be reduced. Further, since the belt bendability is improved as the belt thickness is reduced, the crack resistance is improved by reducing the stress, and the fuel efficiency is improved by reducing the bending loss.

  The manufacturing method of the V-ribbed belt of the present invention includes a stretch layer mounting step of mounting a stretch layer member for forming a stretch layer on a cylindrical drum, a core wire spinning step of winding a core wire, and a compression rubber layer. A compressed rubber layer winding step for winding an unvulcanized rubber sheet for the above, a non-woven fabric winding step for winding a non-woven fabric containing thermoplastic fibers on the wound unvulcanized rubber sheet, the stretch layer member, the core wire, Unvulcanized rubber sheet and nonwoven fabric are vulcanized at a temperature higher than the melting point of the thermoplastic fiber to obtain a vulcanized sleeve. On the nonwoven fabric side of the vulcanized sleeve, only the side portion of the compressed rubber layer is ground. Including the grinding process of forming with.

  Specifically, in the production method of the present invention, as the stretch layer mounting step, the stretch layer member is mounted on a cylindrical forming drum. The attachment method of the stretch layer member can be selected according to the type of the stretch layer member. In the case of a sheet-like member, the stretch layer member may be wound around a cylindrical drum. The member may be placed on a cylindrical drum.

  In the present invention, if necessary, an adhesive rubber layer mounting step for mounting the adhesive rubber layer may be included as a pre-process and / or a post-process of the core spinning process. When the adhesive rubber layer mounting step is included as a pre-process, the adhesive rubber layer mounting step includes, for example, an annular laminate of an unvulcanized rubber sheet for forming the adhesive rubber layer and a member for forming the stretched layer. A method of covering a cylindrical drum, a method of winding a laminate of an unvulcanized rubber sheet for forming an adhesive rubber layer and a member for forming an extension layer around the cylindrical drum, on the attached member for the extension layer A method of winding an unvulcanized rubber sheet for forming the adhesive rubber layer may be used. When the adhesive rubber layer mounting step is included as a post-process, the adhesive rubber layer mounting step includes, for example, a method of winding an unvulcanized rubber sheet for forming the adhesive rubber layer on the core wire, and an adhesive rubber layer. For example, a method of winding a laminate of an unvulcanized rubber sheet and a member for forming a compressed rubber layer on a core wire may be used.

  Therefore, in the cord spinning step, the cord is usually spirally formed on the stretch layer member or the unvulcanized sheet for the adhesive rubber layer attached in the step, depending on the presence or absence of the adhesive rubber layer winding step. Spin and wrap around. In the compressed rubber layer winding step, the unvulcanized rubber is usually used to form a compressed rubber layer (rib rubber layer) on the core wire spun in the step or the wound unvulcanized sheet for the adhesive rubber layer. Wrap the sheet.

  Furthermore, in this invention, in the nonwoven fabric winding process, the nonwoven fabric containing the thermoplastic fiber which has melting | fusing point which melt | dissolves at the vulcanization temperature of a belt is wound around the surface of the unvulcanized rubber sheet for forming a compression rubber layer. When the fibers constituting the nonwoven fabric are oriented in a predetermined direction, the fibers are preferably wound with the longitudinal direction of the fibers arranged parallel to the longitudinal direction of the belt.

  In the vulcanization step, the vulcanization method may be a vulcanization can method. The vulcanization temperature may be 3 to 20 ° C, preferably 5 to 15 ° C, more preferably 8 to 12 ° C higher than the melting point of the thermoplastic fiber. The specific vulcanization temperature can be selected depending on the type of rubber, but may be, for example, 140 to 200 ° C, preferably 150 to 180 ° C, and more preferably about 165 to 180 ° C. If the vulcanization temperature is too low, the proportion of non-fibrous parts may be reduced, and if too high, the proportion of fibrous parts may be increased. In this invention, since a nonwoven fabric and a compression rubber layer are integrated by a vulcanization process, the adhesion process of a nonwoven fabric is unnecessary and productivity is also high. Moreover, since the nonwoven fabric is buried in the compressed rubber layer while maintaining the fiber form to some extent during vulcanization, it is also effective for releasing air during vulcanization and releasing from the vulcanization jacket.

  In the grinding step, the V-ribbed belt is usually obtained by grinding the vulcanized sleeve to form ribs on the compressed rubber layer, and then cutting it into a predetermined width and cutting it. As a grinding method, a conventional method can be used. However, since only the side portion of the compressed rubber layer is ground on the nonwoven fabric side of the compressed rubber layer, a composite layer is formed on the bottom surface and the amount of grinding can be reduced.

  Hereinafter, the present invention will be described in more detail based on examples, but the present invention is not limited to these examples. In addition, the detail of the nonwoven fabric used in the Example, the component of a rubber composition, and a core wire, and the evaluation method of the measured evaluation item are shown below.

[Nonwoven fabric]
(Polypropylene (PP) nonwoven fabric of Examples 1 to 6: manufactured by Asahi Kasei Fibers Co., Ltd.)
Example 1: Trade name “P03015”, basis weight 15 g / m ² , thickness 0.14 mm
Examples 2 and 6: trade name “PL2020”, basis weight 20 g / m ² , thickness 0.23 mm
Example 3: Product name “P03025”, basis weight 25 g / m ² , thickness 0.21 mm
Example 4: Product name “P03030”, basis weight 30 g / m ² , thickness 0.27 mm
Example 5: Trade name “P03040”, basis weight 40 g / m ² , thickness 0.34 mm
(Nonwoven fabric of comparative example)
Comparative Example 1: Rayon nonwoven fabric, 30 g / m ² in basis weight, manufactured by Shinwa Co., Ltd., trade name “# 5130”, thickness 0.25 mm
Comparative Examples 2 and 3: Low density polyethylene (PE) nonwoven fabric, basis weight 30 g / m ² , manufactured by Idemitsu Unitech Co., Ltd., trade name “Stratec LL”, thickness 0.3 mm.

[Ingredients of rubber composition]
EPDM polymer: “IP3640” manufactured by DuPont Dow Elastomer Japan Co., Ltd., Mooney viscosity 40 (100 ° C.)
Polyamide short fiber: “66 nylon” manufactured by Asahi Kasei Corporation
Carbon black HAF: “Seast 3” manufactured by Tokai Carbon Co., Ltd.
Paraffin softener: “Diana Process Oil” manufactured by Idemitsu Kosan Co., Ltd.
Organic peroxide: “Parkadox 14RP” manufactured by Kayaku Akzo Corporation
Hydrous silica: “Nippil VN3” manufactured by Tosoh Silica Co., Ltd., specific surface area 240 m ² / g
Anti-aging agent: “Nonflex OD3” manufactured by Seiko Chemical Co., Ltd.
Vulcanization accelerator DM: Di-2-benzothiazolyl disulfide

[Core]
Core wire: A fiber obtained by bonding a cord of total denier 6,000, which is a 2 × 3 twisted configuration of 1,000 denier PET fiber and twisted with an upper twist factor of 3.0 and a lower twist factor of 3.0.

[Heat resistance]
The running test machine used for the heat durability test is 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). Then, a V-ribbed belt is suspended on each pulley so that the winding angle around the tension pulley is 90 ° and the winding angle around the idler pulley is 120 °. Was run. At this time, a load was applied to the drive pulley so that the belt tension was 40 kgf / rib, and a load of 8.8 kW was applied to the driven pulley. Then, the V-ribbed belt was run in this way, and the time until six cracks reaching the core were generated was measured.

[Bending fatigue resistance (crack resistance)]
Using the test machine having the layout shown in FIG. 2, the V-ribbed belt obtained in the example and the comparative example was subjected to a running test of the V-ribbed belt in an atmosphere of 130 ° C. The bending fatigue resistance was evaluated.

[Evaluation of appearance properties]
The rib tip surfaces of the V-ribbed belts obtained in the examples and comparative examples were visually observed and judged according to the following criteria.

4: There is no fluffing of non-woven fiber on the rib tip surface 3: There is a slight fluff of non-woven fiber on the rib tip surface, but it is not noticeable 2: There is fluffing of non-woven fiber on the rib tip surface, which is slightly noticeable 1: Non-woven fiber fluff is present on the entire rib tip.

  Note that “fluffing” in the evaluation criteria means that the rib tip surface includes a thread-like material in the following states (1) and (2).

(1) A state in which the filamentous material in which the fiber shape of the nonwoven fabric is maintained cannot be embedded in rubber and appears on the bottom surface. (2) When the side portion is ground, the fiber shape embedded in the bottom portion (composite layer) A state in which the filamentous material that has been maintained is pulled out of the composite layer due to the effect of the grinder and emerges from the surface.

Examples 1-6 and Comparative Examples 1-3
(Cover for forming stretch layer)
A wide-angle plain woven canvas (thickness: 0.63 mm) using a mixed yarn of 50:50 by weight of cotton fiber and polyethylene terephthalate fiber was used as the covering fabric. These canvases were immersed in an RFL solution, and then heat treated at 150 ° C. for 2 minutes to obtain an adhesion-treated canvas. Furthermore, a laminate was produced by laminating a rubber sheet (thickness 0.5 mm) for forming an adhesive rubber layer obtained from the rubber composition shown in Table 1 on this adhesion-treated canvas.

(Rubber sheet for forming a compressed rubber layer and an adhesive rubber layer)
A rubber sheet for forming an adhesive rubber layer having a thickness of 2.2 mm is formed by kneading the rubber composition shown in Table 1 with a Banbury mixer and rolling with a calender roll to form a compressed rubber layer. Was made to a thickness of 0.5 mm.

(Manufacture of belts)
An adhesive rubber layer is formed by laminating a laminate of an outer cloth for forming an extension layer and a rubber sheet for forming an adhesive rubber layer on the outer periphery of a cylindrical drum (molding die) having a smooth surface. For this reason, the rubber sheet was wound so as to be an outer peripheral surface. After winding the core wire spirally around the outer peripheral surface of the laminate, a rubber sheet for forming an adhesive rubber layer and a rubber sheet for forming a compression rubber layer were further stacked on the core wire. The laminate was wound so that the rubber sheet for forming the compressed rubber layer was the outermost peripheral surface. Further, a nonwoven fabric was wound around the outermost peripheral surface to produce an unvulcanized belt molded body.

  Further, the belt molded body was placed in a vulcanizing can with a vulcanization jacket covered on the outer peripheral side, and vulcanized with pressurized steam under conditions of 180 ° C., 0.9 MPa for 25 minutes.

  Further, after cooling, the vulcanized belt sleeve obtained by removing (releasing) the vulcanization jacket is compressed rubber with a grinding wheel (grinding stone) having a predetermined shape for forming a V-shaped groove. Only the side of the layer was ground to form a plurality of ribs (grooves with a V-shaped cross section). Then, the vulcanized belt sleeve formed with the plurality of ribs is cut into a predetermined width so as to be cut by a cutter, and then the inner peripheral side and the outer peripheral side are reversed, whereby the V-ribbed belt having the structure shown in FIG. Got.

  On the surface of the rib portion of the obtained V-ribbed belt, a part of the nonwoven fabric is melted and deformed into a non-fibrous part, and the fibrous part and a part of the non-fibrous part are embedded in the compressed rubber layer to form a composite layer. Was formed. The rib part surface of the V-ribbed belt obtained in Example 2 and a scanning electron micrograph (SEM photograph) of the cross section are shown in FIGS. 3 and 4, respectively. In FIGS. 3 and 4, the dark colored part is a part derived from the nonwoven fabric, and the light colored part is a part derived from the compressed rubber layer. As apparent from FIGS. 3 and 4, the surface of the rib portion of the V-ribbed belt of Example 1 has a fibrous portion (light and thin linear portion) and a non-fibrous portion (dark and widened portion). ) And a rubber composition (dark portions) were formed. Specifically, in FIG. 3, the central portion where the fibrous portion can be observed is the bottom surface (non-ground surface), and the left and right side portions are ground surfaces.

  In Comparative Example 3, a V-ribbed belt was manufactured by a method using a mold described in Examples of Japanese Patent Application Laid-Open No. 2013-145032.

(Evaluation of belt)
Table 2 shows the evaluation results of the heat resistant durability, the bending fatigue resistance, and the appearance of the rib surface of the manufactured V-ribbed belt.

  As is clear from the results in Table 2, Examples 1 to 6 in which the bottom of the compressed rubber layer formed a composite layer of three components, and the nonwoven fabric melted, the fiber shape disappeared, and a single film-like resin layer Comparing with Comparative Examples 2 and 3 in which (skin layer) was formed, Examples 1 to 6 had a long time to crack initiation and excellent durability in both heat resistance and bending fatigue resistance.

Moreover, when Examples 1-6 are compared with Comparative Example 1 in which the nonwoven fabric remains in a fiber shape, even if Example 5 has a large basis weight of 40 g / m ² , durability is superior to Comparative Example 1. It was.

  In the examples, the smaller the nonwoven fabric, the longer the time until cracking occurred in the bending fatigue resistance test.

  From the above, the examples in which the bottom of the compressed rubber layer is a composite layer of three components of rubber, resin, and fiber are comparative examples in which the bottom of the compressed rubber layer is a film-like resin layer (skin layer) or a thick nonwoven fabric. Compared with, the belt was easily bent and was excellent in durability.

  As for the appearance, compared with the belt of Comparative Example 1 in which the non-woven fabric is fluffed on the entire bottom surface of the compressed rubber layer, the belts of Examples 1 to 6 have no or no noticeable non-woven fabric fluff. there were.

  FIG. 5 shows a photograph of the rib portion of the V-ribbed belt obtained in Example 2. The scratches and spots were not transferred from the vulcanized jacket, and the appearance was good. That is, in the SEM photograph, it seems that rubber and non-woven fabric are mixed, but the non-woven fabric was not noticeable visually.

  In addition, although the photograph of the rib part of the V ribbed belt (reference example 1) manufactured without using a nonwoven fabric is shown in FIG. 6, the damage | wound and a stain were transcribe | transferred from the vulcanization jacket.

  The V-ribbed belt of the present invention can be used as a friction transmission belt of a transmission device such as an automobile engine accessory drive.

DESCRIPTION OF SYMBOLS 1 ... Stretch layer 2 ... Core wire 3 ... Adhesive rubber layer 4 ... Compression rubber layer 4a ... Grinding surface 5 ... Composite layer

Claims (9)

A compression rubber layer containing a vulcanizate of the rubber composition, a core wire, and an extension layer; and a side surface of the compression rubber layer is a ground surface in contact with the pulley, and a bottom portion of the compression rubber layer is a pulley. A V-ribbed belt that is a non-ground surface that does not contact,
The bottom surface is a composite layer containing a non-woven fabric heat-treated product containing thermoplastic fibers that melt at the vulcanization temperature of the rubber composition and a vulcanized product of the rubber composition, and the non-woven fabric heat-treated product However, the V-ribbed belt is formed of a fibrous portion in which the fiber shape remains and a non-fibrous portion in which the fiber shape has disappeared.   The V-ribbed belt according to claim 1, wherein the thermoplastic fiber is at least one selected from the group consisting of polyolefin fibers and polyurethane fibers.   The V-ribbed belt according to claim 1 or 2, wherein the thermoplastic fiber is a polypropylene fiber. V-ribbed belt according to claim 1, basis weight of the nonwoven fabric is 12 to 30 g / ^{m 2.}   The V-ribbed belt according to any one of claims 1 to 4, wherein the nonwoven fabric has an average thickness of 0.03 to 0.3 mm.   The V-ribbed belt according to any one of claims 1 to 5, wherein the fibers of the nonwoven fabric are oriented in a predetermined direction, and the longitudinal direction of the fibers is parallel to the longitudinal direction of the belt.   The V-ribbed belt according to any one of claims 1 to 6, wherein the compressed rubber layer has a rib portion, and an average thickness of the rib portion is 54% or less with respect to an average thickness of the entire V-ribbed belt.   Stretch layer mounting process for mounting a stretch layer member to form a stretch layer on a cylindrical drum, core spinning process for winding a core wire, and compression for winding an unvulcanized rubber sheet for forming a compressed rubber layer A rubber layer winding step, a non-woven fabric winding step of winding a non-woven fabric containing thermoplastic fibers on the wound unvulcanized rubber sheet, the stretch layer member, the core wire, the unvulcanized rubber sheet, and the non-woven fabric, A vulcanization step of obtaining a vulcanized sleeve by vulcanizing at a temperature higher than the melting point of the thermoplastic fiber, and a grinding step of forming only the side portion of the compressed rubber layer by grinding on the nonwoven fabric side of the vulcanized sleeve. The manufacturing method of the V-ribbed belt in any one of -7.   The process according to claim 8, wherein the vulcanization temperature is 5 to 15 ° C higher than the melting point of the thermoplastic fiber.