JP6059004B2 - Transmission belt and manufacturing method thereof - Google Patents

Description

  The present invention relates to a transmission belt and a manufacturing method thereof.

  Even in the rubber industry, high performance and high performance are desired for automotive parts. Among such rubber products used for automobile parts, there is a power transmission belt, which is widely used for power transmission of auxiliary drives such as an air compressor and an alternator of an automobile. In recent years, there has been a strict demand for quietness in the living environment, and in particular, in automobile drive devices, since sounds other than engine noise are abnormal noise, countermeasures against belt sounding have been demanded.

  Among such transmission belts, V belts can be roughly classified into a polishing belt that forms ribs by polishing and a belt that molds ribs with a mold (mold forming belt) depending on the manufacturing method. . Mold molding belts are obtained by pressing raw rubber against the mold and vulcanizing it. When air is interposed between the mold and rubber, an uneven surface is formed on the belt surface (pulley engagement or contact surface). It becomes non-uniform and causes abnormal noise due to misalignment of pulleys during belt running. For this reason, in the method of manufacturing a mold forming belt, it is necessary to add an air bleeding material on the rib rubber in order to extract air from the mold. Generally, a non-woven fabric is used as the air release material, and air accumulation is prevented by winding the non-woven fabric around the belt surface. However, even in the method using a nonwoven fabric, when the nonwoven fabric is wound, the joint portions of adjacent nonwoven fabrics overlap (stack) or become a butt joint (a gap is formed), and a step or uneven surface is generated at this joint portion. . Furthermore, in the friction transmission V-belt, in order to suppress fluctuations in rotational speed, slip noise generated under high load conditions, and noise generated due to adhesive rubber having adhesive wear adhering to the groove bottom between ribs, It is also necessary to reduce the surface friction coefficient.

  Japanese Patent No. 4251870 (Patent Document 1) includes a main body having an elastic body and having a tensile member along the longitudinal direction, the main body having a predetermined shape and engaging with a pulley. A non-woven fabric member, which is a pulley engaging region having an engaging surface and on which irregularly oriented fibers are arranged, is obtained by vulcanizing the material of the elastic body, so that both the elastic body and the non-woven fabric member A belt having the pulley engagement region mixed with the elastic body so as to exist over the entire surface of the pulley engagement surface, and the elastic body further including a fiber filler inside the pulley engagement region. It is disclosed. In this document, a nonwoven fabric member made of cellulose is mixed on the pulley engaging surface so as not to have a clear boundary with the rubber of the main body. Further, the nonwoven member may be formed from one or more layers and has the advantage of escaping gas generated in the molding process and is described as having the effect of noise and weight loss (wear resistance). ing.

  Japanese Patent Application Laid-Open No. 2010-101289 (Patent Document 2) discloses a transmission belt having an ethylene-α-olefin elastomer-based elastomer tooth, the elastomer tooth being covered with a barrier layer made of a thermoplastic material, The barrier layer is covered with an outer cover formed of woven or non-woven fabric, and the outer cover that is at least on the flank of the elastomeric teeth is partially included within a portion of the thickness of the barrier layer. A transmission belt is disclosed. This document describes that the woven fabric or non-woven fabric forming the cover can be formed of a fiber coated with polyethylene with a material having a melting point higher than the vulcanization temperature in order to retain the fiber structure after vulcanization. Yes.

  In these belts, the belt surface is coated with a non-woven fabric or a woven fabric and is modified so as to reduce the friction coefficient. Therefore, abnormal noise during belt running can be reduced to some extent. However, peeling of the nonwoven fabric or woven fabric from the belt surface, which causes noise during the belt running, is likely to occur. Moreover, the joint part of a nonwoven fabric or a woven fabric is also non-uniform | heterogenous and produces a level | step difference, and this also becomes a factor which generate | occur | produces abnormal noise at the time of belt travel. In addition, when using a nonwoven fabric made of long fibers (for example, spunbond nonwoven fabric), the fibers that make up the fabric are subject to stress concentration due to repeated bending of the belt, causing fatigue failure and cracking in the belt. [For example, rib cracks (such as cracks in rib corners or rib grooves)] tend to occur. In particular, such cloth peeling and belt cracking may occur even when a barrier layer is provided as in Patent Document 2.

  On the other hand, JP 2009-533606 A (Patent Document 3) discloses a ribbed transmission belt having a tooth portion made of an ethylene / α-olefin elastomer-based elastomer, and at least a side surface of the tooth portion has a molecular weight. Ribbed power transmission belts are disclosed which are covered with a film of a thermoplastic resin that is at least 30% and contains at least 30% of at least one low density polyethylene and is between 50000 g / mol and 200000 g / mol. ing. This document describes that a thermoplastic resin is applied to a rubber surface in an uncrosslinked or partially crosslinked state, and then partially or completely crosslinked in a belt vulcanization process. However, in the belt of this document, a crosslinked thermoplastic resin is used, but even a film made of such a thermoplastic resin is easily peeled off from the rib surface while the belt is running. In addition, it is difficult to form a smooth surface by coating, and a cross-linking step is required, and productivity is low.

Japanese Patent No. 4251870 (Claim 1, paragraphs [0014] [0017] [0022]) JP 2010-101489 A (Claim 1, paragraph [0051]) JP 2009-533606 A (Claims, paragraphs [0026] to [0040], [0050] to [0056])

  Accordingly, an object of the present invention is to provide a transmission belt that can suppress the peeling of the reinforcing cloth that covers the compressed rubber layer (particularly, the compressed rubber layer having a rib portion) and can improve or improve the belt life and a method for manufacturing the same. is there.

  Another object of the present invention is to provide a transmission belt capable of reducing the friction coefficient of the belt surface and a method for manufacturing the same.

  Still another object of the present invention is to provide a transmission belt capable of suppressing the generation of abnormal noise and noise during traveling and a method for manufacturing the same.

  Another object of the present invention is to provide a transmission belt excellent in durability and wear resistance and a method for producing the same.

  Still another object of the present invention is to provide a transmission belt that can suppress the occurrence of cracks in a compressed rubber layer (particularly, a rib portion) and a method for manufacturing the same, even if the reinforcing fabric is formed of long fibers.

  As a result of intensive studies to achieve the above-mentioned problems, the present inventors have covered a compressed rubber layer (particularly, a compressed rubber layer having ribs) or a surface thereof with a reinforcing cloth (for example, a nonwoven fabric formed of long fibers). In the transmission belt having the above structure, the reinforcing cloth is covered with a base layer formed of a thermoplastic resin, and the base layer is exposed from the opening provided in the reinforcing cloth (particularly, the base layer is melted in the opening). The adhesion between the compressed rubber layer (or the base layer) and the reinforcing cloth can be improved, and the peeling (or detachment) of the reinforcing cloth can be suppressed, and the friction coefficient of the belt (or belt surface). Can reduce the sound or noise during belt running, and even if the reinforcing fabric is formed of long fibers, the long fibers can be cut appropriately by the opening, so Reduce stress concentration Therefore, cracks in the compressed rubber layer can be prevented or suppressed, and excellent properties (durability, etc.) of a reinforcing fabric formed of long fibers (for example, a spunbond nonwoven fabric formed of long fibers) The present invention has been completed by finding that the wear resistance and the like can be improved or maintained.

  That is, the transmission belt of the present invention is a transmission belt including at least a stretch rubber layer, a core wire embedded along the belt longitudinal direction, and a compression rubber layer, and is further laminated on the compression rubber layer. Reinforcement cloth having an opening (or a hole) (or having an opening) laminated on the underlayer [undercoat layer covering the compressed rubber layer (or the surface of the compressed rubber layer)] and the underlayer (Reinforcing cloth covering the underlayer), and a transmission belt in which the underlayer is exposed from the opening.

  The underlayer may be formed of a thermoplastic resin (for example, an olefin resin). In particular, the underlayer is formed of a thermoplastic resin having a melting point or a softening point equal to or lower than the vulcanization temperature of the stretched rubber layer, and a melt of the thermoplastic resin penetrates from the opening (the underlayer is exposed in an infiltrating manner). It may be. The average thickness of the underlayer may be, for example, about 1 to 500 μm.

  The reinforcing fabric may be a non-woven fabric, and particularly a non-woven fabric formed of long fibers. Typically, the reinforcing fabric may be a spunbond nonwoven fabric composed of propylene fibers. In the nonwoven fabric formed of long fibers, the long fibers may be oriented in the belt longitudinal direction (or along the belt longitudinal direction).

  The opening of the reinforcing cloth may be formed by opening or tearing a previously formed cut in the belt forming process. For example, the reinforcing cloth may have a linear cut, and the opening may be formed by the opening of the linear cut. In such a reinforcing cloth, the cutting direction of the linear cut may be a direction intersecting the belt longitudinal direction. In particular, the reinforcing fabric is a nonwoven fabric (particularly a spunbond nonwoven fabric) formed of long fibers, the long fibers are oriented along the belt longitudinal direction, and the cut direction of the linear cut is the belt longitudinal direction (or long It may be a direction that intersects the fiber orientation direction.

  The transmission belt of the present invention may be a belt having a rib portion in which the compressed rubber layer extends in the belt longitudinal direction. In such a belt, in particular, the reinforcing cloth is formed with an opening (bent opening, a dogleg-shaped opening) that is bent (along the rib) so as to cross the corner of the rib. Also good.

  The reinforcing cloth may usually have a plurality of openings. For example, the reinforcing cloth may have a plurality of openings that extend in both the belt longitudinal direction (or the longitudinal direction of the reinforcing cloth) and the belt width direction (or the width direction of the reinforcing cloth). A specific reinforcing cloth may have a plurality of openings formed at an average interval of 5 to 40 mm in the belt longitudinal direction. Thus, by forming a plurality of openings extending in both directions (two-dimensional or planar), the adhesiveness between the compressed rubber layer and the reinforcing cloth can be improved more efficiently.

  In the reinforcing cloth, the area (total area) of the opening may be about 10 to 50% of the entire surface (outer surface or outermost surface) of the reinforcing cloth.

  In the transmission belt of the present invention, the compression rubber layer may be laminated on the stretch rubber layer, and the core wire may be embedded in the stretch rubber layer. Further, a power transmission belt in which the stretch rubber layer includes short fibers and the compression rubber layer does not include short fibers may be used. In addition, the transmission belt of the present invention may be a V-ribbed belt in which the compressed rubber layer usually has a plurality of rib portions extending in the belt longitudinal direction.

  In the present invention, an unvulcanized laminated rubber in which a non-vulcanized rubber sheet for forming an extended rubber layer, a core wire, and an unvulcanized rubber sheet for forming a compressed rubber layer are wound around a cylindrical drum. Further, a reinforcing cloth having a sheet for forming a base layer (sheet for base layer) and a cut (or a hole, for example, a linear cut) for forming an opening is wound on the sheet. The power transmission belt comprising: a winding step for obtaining a vulcanized rubber sleeve; and a vulcanization forming step for pressing the unvulcanized belt sleeve obtained in the winding step against a mold and vulcanizing and heating the die. This manufacturing method is also included.

  In this method, in the vulcanization molding step, a cut (for example, a linear cut) may be opened by pressing to form an opening (for example, a long and narrow opening). In the vulcanization molding process, a mold corresponding to the rib portion is used to form a compressed rubber layer having a rib portion extending in the longitudinal direction of the belt and an opening (or tearing) that cuts across the corner portion of the rib portion. ).

  Further, in the above method, the sheet for forming the base layer is formed of a thermoplastic resin having a melting point or a softening point equal to or lower than the vulcanization temperature of the stretched rubber layer, and at the pressing and vulcanization temperature in the vulcanization molding step. The thermoplastic resin may be melted by heating to form a base layer (film-like skin layer), and a thermoplastic resin melt may be allowed to enter from the opening.

  In the present invention, the reinforcing cloth provided with the opening and the base layer are combined and the base layer is exposed from the opening, so that the adhesive property between the compressed rubber layer (or the compressed rubber layer on which the base layer is formed) and the reinforcing cloth is improved. It can improve or improve, and can suppress peeling (or dropping) of the reinforcing cloth covering the compressed rubber layer (particularly, the compressed rubber layer having a rib portion). In addition, by exposing the underlayer formed of a thermoplastic resin or the like from the opening (particularly, allowing the underlayer to enter the opening), the exposed underlayer can reduce the friction coefficient of the belt surface.

  In addition, when the belt surface is dried and shifts to a wet state by absorbing water, the friction coefficient with the pulley decreases rapidly, and when a large difference occurs in the friction coefficient before and after absorbing water, Although there is a problem that abnormal noise occurs due to the stick-slip phenomenon, in the present invention, it is usual to adjust the area of the opening in the reinforcing fabric (or the degree of exposure of the underlayer exposed to the belt surface or the opening). The difference between the friction coefficient at the time of (DRY) and the friction coefficient at the time of wetting (WET) can be easily reduced (and these friction coefficients can be easily brought close to 1). Therefore, in the belt of the present invention, it is possible to suppress the generation of abnormal noise (sound generation) and noise during traveling.

  Furthermore, in the belt of the present invention, as described above, since the adhesiveness of the reinforcing cloth covering the belt surface can be improved or improved, excellent characteristics derived from the reinforcing cloth, for example, durability and wear resistance are improved or improved. You can also In particular, in the present invention, even if the reinforcing cloth is formed of long fibers, the stress concentration on the long fibers due to the bending of the belt can be reduced by cutting the long fibers by the openings, and cracks in the compressed rubber layer (particularly the rib portion) can be reduced. Generation can be suppressed. Therefore, the belt of the present invention can maintain the excellent belt characteristics as described above over a long period of time.

FIG. 1 is a schematic perspective sectional view showing an example of a transmission belt of the present invention. FIG. 2 is a schematic cross-sectional view showing a state in which each member sheet that is a raw material of the transmission belt is wound around a cylindrical forming drum in the embodiment. FIG. 3 is a schematic perspective view (a) and a schematic cross-sectional view (b) showing a state where the forming drum of FIG. 2 around which each member sheet is wound is set in a vulcanization mold. FIG. 4 is a schematic perspective view (a) and a schematic cross-sectional view (b) showing a state where the flexible jacket in the forming drum of FIG. 3 is expanded. FIG. 5 is a diagram illustrating a layout of a testing machine used for measuring the friction coefficient (during DRY) in the example. FIG. 6 is a diagram showing a layout of a testing machine used for measuring the friction coefficient (WET) in the example. FIG. 7 is a diagram illustrating a layout of a testing machine used in the bending fatigue resistance test in Examples. FIG. 8 is a schematic diagram showing a long-fiber nonwoven fabric with perforations.

[Power transmission belt]
The power transmission belt of the present invention is a power transmission belt including at least a stretched rubber layer, a core wire embedded in the longitudinal direction of the belt, and a compression rubber layer, and further includes a lower layer laminated on the compression rubber layer. A base layer [a base layer covering the compressed rubber layer (or the surface of the compressed rubber layer)] and a reinforcing cloth laminated on the base layer and having an opening (or a hole) (a reinforcing cloth covering the base layer) It is a transmission belt provided. And from this opening part, a foundation layer (a part of foundation layer) is exposed (or infiltrated). That is, in the transmission belt of the present invention, the compression rubber layer (or the foundation layer) and the reinforcement cloth are exposed by exposing the foundation layer from the opening provided in the reinforcement cloth (particularly by melting and entering the foundation layer into the opening). Improved or improved the adhesive strength.

  FIG. 1 is a schematic sectional view showing an example of a transmission belt (V-ribbed belt) according to the present invention, and is a schematic perspective sectional view of the transmission belt cut in the belt width direction.

  In this example, the V-ribbed belt 1 has rib portions 6 extending in a plurality of rows along the longitudinal direction of the belt on the inner peripheral surface (belt belly surface or belt belly surface side) of the belt main body. The cross-sectional shape in the direction perpendicular to the longitudinal direction is such that the width decreases from the belt outer peripheral side (the side that does not have a rib portion and does not engage with the pulley) toward the inner peripheral side (taperes toward the tip). It is trapezoidal.

  The V-ribbed belt 1 has a laminated structure, and is formed of a rubber composition containing short fibers 3 from the outer peripheral side (or belt back side) of the belt main body toward the inner peripheral side (belt abdomen side). A stretch rubber layer 4, a core wire 2, a compression rubber layer (rib rubber layer) 5 having a rib portion 6 extending in the belt longitudinal direction, a base layer 7 formed of a thermoplastic resin (or a melt thereof), and a large number of openings 8A. The reinforcing cloths 8 having the above are sequentially laminated.

  Specifically, the cores 2 are embedded in the stretched rubber layer 4 along the longitudinal direction of the belt while the cores 2 maintain a predetermined interval. That is, the core 2 is not at a level in contact with the stretch rubber layer 4 but is mainly embedded in the stretch rubber layer 4 [for example, more than half of the total volume of each core 2 (for example, 60% or more of the volume is Embedded in the stretched rubber layer 4]. In other words, a line L connecting the centers (or axial centers) of the cores 2 exists in the stretched rubber layer 4 (or the stretched rubber layer 4 extends beyond the line L toward the compressed rubber layer 5 side). Invaded). By embedding the core wire 2 in the stretched rubber layer 4 in this way, high adhesion (or adhesiveness) between the stretched rubber layer 4 and the compressed rubber layer 5 is realized without providing a separate adhesive rubber layer. Yes.

  The short fibers 3 included in the stretched rubber layer 4 are oriented in a random direction, and the compressed rubber layer 5 does not include short fibers.

  The surface of the compressed rubber layer 5 (or the rib portion 6) was formed of long fibers via an underlayer [film-like underlayer (skin layer)] 7 formed by melting the thermoplastic resin. It is covered with a non-woven reinforcing cloth 8. In the reinforcing cloth 8, the long fibers are oriented along the belt longitudinal direction. The opening 8A provided in the reinforcing cloth 8 has a bent shape (a long and thin shape extending in the belt width direction). That is, the reinforcing cloth 8A mainly has an opening (a bent opening, a dogleg shape, or a ridge) bent along the rib 6 so as to cross or intersect the corner (or corner) 6A of the rib 6. Shaped opening) 8A.

  In addition, the reinforcing cloth 8 is formed with a large number of openings 8A arranged at predetermined intervals so as to spread in the belt longitudinal direction and the belt width direction (in a zigzag pattern or a continuous spot pattern). Further, the base layer 7 (or a part of the base layer 7) is exposed (exposed to the belt surface) from the opening 8A in such a manner that the molten thermoplastic resin enters.

  By exposing the base layer from the opening in this manner, high adhesion (or adhesiveness) between the compressed rubber layer (or the base layer) and the reinforcing cloth is realized. In addition, such an exposed underlayer can reduce the friction coefficient of the belt surface. In addition, the long fibers constituting the reinforcing fabric are cut (or divided) at some places by the opening, and the stress concentration associated with the bending of the belt can be alleviated, so that the compression rubber layer (or rib portion) is efficiently cracked. Can be prevented or suppressed. In particular, as shown in the figure, by arranging the opening so as to mainly cross the corner portion, it is easy to efficiently prevent cracks at the corner portion of the rib portion where stress is easily collected.

  As shown in FIG. 8 to be described later, the opening as shown in the figure has a large number of linear cuts (such as perforations 8B in FIG. 8) formed along the longitudinal direction and the belt width direction of the belt. By using the reinforcing cloth 8 having the belt and press-molding the belt in a mold as will be described later, the linear cut is torn (opens or under-opens). At this time, the rib part is formed with the pressurization, but it is easily affected by the pressure at the position where the corner part of the rib part is formed. An opening that is torn is formed. Therefore, the reinforcing cloth does not need to form openings in all the cuts provided in advance, and may have cuts (not shown) that remain without opening. Such remaining cuts (for example, perforations that do not form openings in the perforations 8B in FIG. 8) also serve to cut the long fibers.

(Stretch rubber layer)
The rubber composition forming the stretched rubber layer (rubber composition for the stretched rubber layer) is not particularly limited, but a rubber composition containing a rubber component and a vulcanizing agent or a crosslinking agent is usually 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 noise reduction.

  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). The proportion of diene can be selected from a range of about 4 to 15% by mass, for example, 4.2 to 13% by mass (for example, 4.3 to 12% by mass), preferably 4.4 to 11.5% by 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-butyl) Peroxy-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 (cross-linking aid or co-vulcanizing agent) in order to increase the degree of cross-linking 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 the rubber component in terms of solid content. More 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.), metal oxides (eg, zinc oxide, magnesium oxide, calcium oxide, barium oxide, iron oxide, copper oxide, titanium oxide, aluminum oxide, etc.), softeners (paraffin oil, naphthene) Oils such as system oils and process oils), processing agents or processing aids (stearic acid, metal stearate, wax, paraffin, fatty acid amide, etc.), anti-aging agents (antioxidants, thermal anti-aging agents, bending) Anti-cracking agent, anti-ozone degradation agent, etc.), coloring agent, tackifier, plasticizer, coupling agent (silane coupling agent, etc.), stabilizer (purple) Linear absorption agents, antioxidants, antiozonants, thermal stabilizers, etc.), a lubricant, a flame retardant, an antistatic agent and the like. 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 ratio of the metal oxide (such as zinc oxide) may be about 1 to 15 parts by mass (particularly 2 to 10 parts by mass), and softener (oil such as paraffin oil) 1-30 mass parts (especially 5-25 mass parts) may be sufficient, and the ratio of a processing agent (stearic acid etc.) is 0.1-5 mass parts (especially 0.5-3 mass parts). Part) degree.

In particular, the stretch rubber layer may usually further contain short fibers in order to suppress abnormal noise generated due to adhesion of the back rubber during back drive. Examples of the fibers constituting the short fibers include natural fibers (cotton, hemp, etc.), regenerated fibers (rayon, acetate, etc.), synthetic fibers (polyolefin fibers such as polyethylene and polypropylene, styrene fibers such as polystyrene, polyfluoroethylene, etc. Fluorinated fibers such as acrylic fibers, vinyl alcohol fibers such as polyvinyl alcohol, polyamide fibers, polyester fibers, wholly aromatic polyester fibers, and aramid fibers). Among the fibers, from the viewpoint of high modulus, synthesis of polyester fibers (polyalkylene arylate fibers) mainly composed of C _2-4 alkylene arylates such as ethylene terephthalate and ethylene-2,6-naphthalate, aramid fibers, etc. Examples include fibers. These short fibers can be used alone or in combination of two or more.

  Among these fibers, cellulose fibers such as cotton and rayon, polyester fibers [for example, polyethylene terephthalate fibers (PET fibers), polyethylene naphthalate fibers (PEN fibers), polytrimethylene terephthalate fibers (PTT fibers)] (PET fibers, etc.), polyamide fibers (polyamide 6, aliphatic polyamide fibers such as polyamide 66, aramid fibers, etc.) are widely used.

  The short fibers may be treated with a conventional adhesion treatment (or surface treatment), for example, resorcin-formalin-latex (RFL) solution, in order to improve dispersibility and adhesion in the rubber composition.

  The average fiber length of the short fibers may be, for example, about 0.01 to 10 mm, preferably 0.05 to 5 mm, more preferably about 0.1 to 3 mm (for example, 0.2 to 1 mm). The average fiber diameter of the short fibers is, for example, about 5 to 50 μm, preferably 7 to 40 μm, and more preferably about 10 to 30 μm. By setting it as such fiber length, a short fiber can be penetrate | invaded efficiently between core wires, the expansion | extension rubber | gum layer can be reinforced efficiently, and generation | occurrence | production of adhesive wear can be suppressed efficiently.

  The ratio of the short fiber is, for example, 1 to 50 parts by mass, preferably 5 to 40 parts by mass, and more preferably about 10 to 35 parts by mass with respect to 100 parts by mass of the rubber component.

  The orientation direction of the short fibers in the stretched rubber layer is not particularly limited, and may be oriented in a random direction or in a predetermined direction such as a belt direction. Among these, it is preferable to orient in random directions from the viewpoint that the generation of cracks and cracks from multiple directions can be suppressed. Furthermore, when short fibers (for example, milled fibers) having a bent portion as the short fibers are oriented in random directions, resistance can be expressed against forces acting from more directions.

  The thickness of the stretched rubber layer (average thickness, thickness to the contact portion with the compressed rubber layer) is, for example, about 0.2 to 6 mm, preferably about 0.3 to 5 mm, and more preferably about 0.5 to 3 mm. Also good.

(Core)
The core wire extends in the belt longitudinal direction and is embedded in the belt body. As for the core wire, normally, a plurality of core wires are embedded in parallel at a predetermined pitch parallel to the longitudinal direction of the belt, and the interval between adjacent core wires (spinning pitch) is, for example, 0.5 to It is 3 mm, preferably 0.8 to 1.5 mm, more preferably about 1 to 1.3 mm.

  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 is, 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.

Examples of the fibers constituting the core wire include natural fibers (cotton, hemp, etc.), regenerated fibers (rayon, acetate, etc.), synthetic fibers (olefin fibers such as polyethylene and polypropylene, styrene fibers such as polystyrene, polyfluoro, etc. And fluorine fibers such as ethylene, acrylic fibers, vinyl alcohol fibers such as polyvinyl alcohol, polyamide fibers, polyester fibers, wholly aromatic polyester fibers, and aramid fibers). Among the fibers, from the viewpoint of high modulus, synthesis of polyester fibers (polyalkylene arylate fibers) mainly composed of C _2-4 alkylene arylates such as ethylene terephthalate and ethylene-2,6-naphthalate, aramid fibers, etc. Fibers are generally used, and polyester fibers [polyethylene terephthalate fibers (PET fibers), polyethylene naphthalate fibers (PEN fibers), polytrimethylene terephthalate fibers (PTT fibers)], and aramid fibers are preferable. Since the polyester fiber is contracted by heat, it is excellent in belt tension maintenance. On the other hand, since the aramid fiber has a higher tensile strength than the polyester fiber, it can compensate for a part that cannot be realized by the polyester fiber with respect to the demand for high tension and high load.

  The fiber may be a multifilament yarn. The fineness of the multifilament yarn may be, for example, about 2000 to 10000 denier (particularly 4000 to 8000 denier).

  In order to improve the adhesion to rubber, the core wire may be subjected to an adhesion treatment. In the adhesion treatment, generally, the fibers can be immersed in a resorcin-formalin-latex liquid (RFL liquid) and then dried by heating to form a uniform adhesive layer on the surface. In addition to this adhesion treatment, the core fiber is pretreated with a conventional adhesive component, for example, an epoxy compound (epoxy resin, etc.), a reactive compound (adhesive compound) such as an isocyanate compound, and then RFL. You may process with a liquid. The RFL liquid is a composition in which an initial condensate (prepolymer) of resorcin and formalin is mixed with latex. Examples of the latex include chloroprene, styrene-butadiene-vinylpyridine terpolymer, hydrogenated nitrile rubber (H-NBR), and NBR.

  The core wire is not particularly limited as long as it is in the belt body, and may be embedded in either the stretch rubber layer or the compression rubber layer, and between the stretch rubber layer and the compression rubber layer as described later. An adhesive rubber layer may be interposed between and embedded in the adhesive rubber layer. In the present invention, the core wire is preferably embedded in the stretch rubber layer and / or the compression rubber layer without using an adhesive rubber layer, and may be embedded in the stretch rubber layer. That is, it is particularly preferable that the core wire is embedded in the stretched rubber layer, not in a mode embedded in the adhesive rubber layer or a mode in contact with the stretched rubber layer.

  When embedded in such a stretched rubber layer, the core wire may be embedded in the stretched rubber layer at least in part (for example, the remainder may be embedded in the compressed rubber layer). It may be embedded in the stretch rubber layer. Since the core wire is embedded in the stretched rubber layer in this manner, high adhesion or adhesion can be ensured between the stretched rubber layer and the compressed rubber layer without requiring an adhesive rubber layer. The extent to which the core wire is embedded in the stretch rubber layer is, for example, the total volume of the core wire (each core wire) (or the entire circumference of the core wire or the cross section of the core wire or the core wire diameter is 100%. Can be selected from an average range of 30% or more (for example, 35 to 100%) of the degree of invasion or burying of the core wire, for example, 40% or more (for example, 45 to 99%), preferably 50% or more (for example, 55 to 98%), more preferably 60% or more (for example, 60 to 95%), and usually embedded in excess of 50% (for example, 55% or more, preferably 60% or more). Also good. Note that all of the core wires (total volume) may be embedded in the stretched rubber layer.

(Compressed rubber layer)
The rubber composition for forming the compression rubber layer (the rubber composition for the compression rubber layer) is not particularly limited, but a rubber composition containing a rubber component and a vulcanizing agent or a crosslinking agent is usually used. In such a rubber composition, the rubber component similar to the rubber component exemplified in the section of the stretched rubber layer can be used as the rubber component. Usually, the rubber component often uses the same or the same type of rubber component (for example, ethylene-α-olefin elastomer) as the rubber component constituting the stretched rubber layer. In addition, preferable aspects, such as the kind of ethylene-alpha-olefin elastomer and the ratio of ethylene and alpha-olefin, are the same as the above.

  In addition, the types and proportions of the vulcanizing agent or crosslinking agent, co-crosslinking agent or crosslinking aid, vulcanization accelerator, and the like can be selected from the same range as the rubber composition of the stretched rubber layer.

  Further, the compressed rubber layer (or rubber composition) may contain various additives exemplified in the section of the stretched rubber layer, and the ratio thereof can be selected from the above range. However, in the present invention, it is preferable that the rubber composition of the compressed rubber layer (particularly the rubber composition forming the rib portion) does not substantially contain fibers such as short fibers. In general, the rib portion of the compressed rubber layer often contains short fibers, but in the present invention, the friction coefficient can be efficiently reduced by laminating the reinforcing cloth 8, so that the blending of short fibers is unnecessary. It is. As described above, since the compressed rubber layer (or the rib portion thereof) does not contain short fibers, the flow of the rubber composition during molding can be maintained well, and the belt life can be improved.

  The thickness of the compressed rubber layer may be, for example, 1 to 25 mm, preferably 1.5 to 16 mm, and more preferably about 2 to 12 mm.

(Underlayer)
The underlayer (skin layer, adhesive layer) is laminated on the compressed rubber layer (or covers the surface of the compressed rubber layer). The underlayer may be formed of rubber or a curable resin (such as a thermosetting resin), but may be generally formed of a thermoplastic resin.

  The thermoplastic resin preferably has a melting point (or softening point) equal to or lower than the vulcanization temperature of the stretch rubber layer (and the compression rubber layer) from the viewpoint of melting in the molding process (vulcanization process). It may have a melting point that is 0-100 ° C., preferably 3-80 ° C., more preferably 5-70 ° C. (especially 10-60 ° C.) lower than the sulfur temperature. When such a thermoplastic resin is used, the base layer can be exposed in a form in which the thermoplastic resin melted from the opening of the reinforcing cloth easily enters with the pressurization during molding, and the compressed rubber layer (or The adhesion or adhesiveness between the base layer) and the reinforcing fabric can be further improved or improved.

  Since the vulcanization temperature of the compression rubber layer is often about 150 to 180 ° C., the specific melting point of the thermoplastic resin is, for example, 165 ° C. or less (for example, 80 to 165 ° C.), preferably 150 ° C. or less ( For example, it may be about 90 to 150 ° C., more preferably about 130 ° C. or less (for example, 100 to 130 ° C.). If the melting point of the thermoplastic resin is too high, the thermoplastic resin does not melt in the vulcanization step, and there is a possibility that sufficient adhesion between the compressed rubber layer and the reinforcing cloth cannot be secured.

  In addition, as the thermoplastic resin, a resin that is not substantially crosslinked is obtained because it is melted and uniformized in the vulcanization process of the stretched rubber layer (and the compressed rubber layer), and an appropriate friction coefficient can be secured. May be used.

  Examples of the thermoplastic resin include olefin resins, acrylic resins, vinyl resins, styrene resins, polyester resins, polyamide resins, polycarbonate resins, polyurethane resins, cellulose resins, and thermoplastic elastomers. It is done. These thermoplastic resins can be used alone or in combination of two or more.

  Of these thermoplastic resins, olefin resins and thermoplastic elastomers are preferred because they can easily form a smooth surface with few irregularities, reduce the coefficient of friction, and have high versatility. Particularly preferred are olefin resins. May be used.

Olefin-based resins include α-olefins such as ethylene, propylene, 1-butene, 2-butene, 1-pentene, 1-hexene, 3-methylpentene and 4-methylpentene (in particular, α-C such as ethylene and propylene). A polymer having _2-6 olefin) as a main polymerization component may be used.

Examples of copolymerizable monomers other than α-olefin include (meth) acrylic monomers [for example, (meth) acrylic acid C _{1- 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.

  Specific examples of the olefin resin 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) 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 preferred, and polyethylene resins such as low density polyethylene are particularly preferred from the viewpoint of easy melting at the vulcanization temperature.

  Examples of the thermoplastic elastomer include olefin elastomers, styrene elastomers, polyester elastomers, polyamide elastomers, and the like.

  Olefin-based elastomers include hard segments formed from polyolefins such as polyethylene and polypropylene, and soft segments formed from rubber components such as olefin rubber, diene rubber, acrylic rubber, butyl rubber, nitrile rubber, and natural rubber. The elastomer etc. which have can be illustrated.

  As the styrene elastomer, an elastomer having a hard segment formed of a styrene polymer such as polystyrene and a soft segment formed of a rubber component such as a diene rubber such as polybutadiene or polyisopropylene or a hydrogenated product thereof. Etc. can be exemplified.

  Examples of the polyester elastomer include an elastomer having a hard segment formed of polyalkylene arylate such as polybutylene terephthalate or polybutylene naphthalate and a soft segment formed of aliphatic polyether or aliphatic polyester. .

  The polyamide-based elastomer has a hard segment formed of an aliphatic polyamide such as polyamide 6, polyamide 66, and polyamide 12, and a soft segment formed of an aliphatic polyether, aliphatic polyester, aliphatic carbonate, or the like. An elastomer etc. can be illustrated.

  These thermoplastic elastomers can be used alone or in combination of two or more. Among these thermoplastic elastomers, hard segments formed from polyolefins such as polyethylene and olefinic rubbers such as ethylene-propylene-nonconjugated diene copolymer rubber (EPDM) because they are easily melted at the vulcanization temperature. An olefin-based elastomer having a soft segment formed of

  Although the foundation layer is laminated on the reinforcing cloth, the foundation layer (or part of the foundation layer) is exposed from the opening of the reinforcement cloth. That is, the base layer is exposed on the belt surface (surface on the ventral surface side) through the opening. Although the mode of exposure is not limited, it is preferable that a part of the base layer [for example, a part of the molten base layer (particularly thermoplastic resin)] is exposed (or protrudes) into the opening. . By exposing in the form of such intrusion, the adhesion between the compressed rubber layer (or the base layer) and the reinforcing cloth can be further improved.

  The average thickness of the underlayer is, for example, 0.1 to 5000 μm (for example, 0.5 to 3000 μm), preferably 1 to 2000 μm (for example, 1.5 to 1000 μm), and more preferably 2 to 700 μm (for example, 3 to 3 μm). About 500 μm), or about 1 to 500 μm (for example, 3 to 300 μm, preferably 5 to 200 μm). In addition, when a part of foundation | substrate layer has penetrated into the opening part, the thickness of the penetration part is not included.

(Reinforcing cloth)
The reinforcing cloth is laminated on the foundation layer. That is, the reinforcing cloth covers the surface of the compressed rubber layer via the base layer. The reinforcing cloth reinforces the compressed rubber layer (or rib surface) and reduces the friction coefficient between the compressed rubber layer and the pulley. Further, by providing the reinforcing cloth, the gas existing between the surface of the compressed rubber layer (or rib portion) and the mold surface at the time of molding can be removed, and the rib surface can be formed more accurately.

  Examples of the reinforcing cloth include a woven cloth (for example, a woven cloth woven in the form of plain weave, twill, satin, etc.), a wide-angle canvas (for example, a wide-angle canvas having a warp and weft crossing angle of about 90 to 120 °). Cloth materials such as knitted fabric and non-woven fabric. Of these reinforcing fabrics, non-woven fabrics are preferable, and from the viewpoint of excellent reinforcing effect (from the viewpoints of wear resistance and tensile strength), wear resistance and particularly non-woven fabrics formed from long fibers (long-fiber non-woven fabrics) are preferred. Can be used.

Examples of the fibers constituting the reinforcing fabric (particularly the nonwoven fabric) include the same fibers as those described in the section of the core wire. Among these, olefin fibers are preferable, and propylene fibers are particularly preferable from the viewpoints of durability and wear resistance. Examples of the propylene polymer (polypropylene resin) constituting the propylene fiber include polypropylene and a propylene-α-olefin copolymer (for example, a random copolymer). In the propylene / α-olefin copolymer, examples of the α-olefin (non-propylene-based α-olefin) include ethylene, 1-butene, 1-pentene, 1-hexene, 1-octene, 4-methyl-1- And C _2-8 alkenes such as pentene. Such a copolymer may be a random copolymer, a block copolymer or the like, but is preferably a random copolymer. In addition, melting | fusing point of a copolymer may be about 125-155 degreeC, for example, Preferably about 130-147 degreeC. Further, in the copolymer, the proportion of α-olefin can be appropriately adjusted according to the melting point and the like, and may be, for example, about 1 to 10 mol%.

  The fiber may be a composite fiber. The composite fiber may be any of a core-sheath type, a sea-island type, a blend type, a parallel type (multilayer bonding type), a radial type, and the like.

  The fiber degree of the fiber is not particularly limited. For example, in the case of a long fiber, the fineness is 0.1 to 10 denier, preferably 0.3 to 5 denier, more preferably about 0.5 to 3 denier. Also good.

Similarly, the basis weight of the reinforcing fabric (particularly the nonwoven fabric) is not particularly limited, and can be selected from a range of about 0.5 to 500 g / m ² (for example, 1 to 300 g / m ² ), for example, 1 to 200 g / m ^2. (For example, ^{2 to} 150 g / m ² ), preferably 3 to 100 g / m ² , more preferably about 5 to 70 g / m ² (for example, 7 to 60 g / m ² ).

  In addition, the thickness (average thickness) of the reinforcing cloth is, for example, 0.05 to 5 mm (for example, 0.07 to 4 mm), preferably 0.1 to 3 mm (for example, 0.15 to 2.5 mm), preferably It may be about 0.2 to 2 mm (for example, 0.3 to 1.5 mm), more preferably about 0.3 to 1 mm.

  The method for producing the nonwoven fabric is not particularly limited, and can be appropriately selected in consideration of productivity. Examples thereof include a spun bond method, a chemical bond method, a thermal bond method, and a needle punch method. Of these production methods, the spunbond method and the thermal bond method are preferable, and the spunbond method is particularly preferable.

  In addition, as a specific method for producing the nonwoven fabric by the spunbond method, for example, a fiber is spun by discharging from a spinneret set to a predetermined temperature with one extruder, and the spun fiber is cooled by cooling air. At the same time, the fiber is pulled and thinned to a predetermined fineness by high-speed air, collected on a collecting belt and deposited to a predetermined thickness to form a web, and then a needle punch, water jet, ultrasonic wave, etc. It can be manufactured by entanglement by a entanglement method such as a method using means, a heat embossing process using an embossing roll, or a method of partially heat-sealing by using hot air through. In addition, when manufacturing the spun bond nonwoven fabric which consists of a core-sheath-type composite fiber, a composite fiber can be spun using two extruders for cores and a sheath, and it can produce similarly.

  In addition, when a nonwoven fabric is a long-fiber nonwoven fabric, the orientation direction of a long fiber is not specifically limited, For example, you may align a long fiber in the longitudinal direction (or along a belt longitudinal direction) of a belt. By setting it as such an orientation direction, the cutting | disconnection of a long fiber and formation of the opening part which crosses the corner part of a rib part can be made to make compatible efficiently as mentioned later.

  And in this invention, it has the characteristics in providing an opening part (hole part) in such a reinforcement cloth, and exposing a base layer from this opening part.

  The shape of the opening (surface shape or cross-sectional shape) is not particularly limited, and may be any of polygonal shapes [triangular shape, quadrangular shape (rectangular shape, square shape, rhombus shape, etc.)], circular shape, elliptical shape, etc. There may be. The opening may have a shape corresponding to the shape of the compressed rubber layer. For example, as shown in the figure, when the compressed rubber layer has a rib portion, the opening crossing the corner portion of the rib portion has a bent shape.

  The opening may be formed in the reinforcing cloth in advance before forming the belt, may be formed in the belt forming process, or may be formed by combining them. For example, as shown in the figure, a reinforcing cloth having a cut (or cut) may be used as the reinforcing cloth, and the cut may be opened (or cleaved) during molding. That is, when a reinforcing cloth having a cut is used, an opening in the belt is formed in the reinforcing cloth in which the cut extends in the cutting direction (the direction crossing the cut). The cut line is not particularly limited as long as the opening can be formed, and may be a dot shape (dot shape), a linear shape (single wire shape, cross shape, radial shape, polygonal shape, circular shape, or the like). In particular, when a reinforcing cloth having a linear cut is used, an elongated (or elongated) opening (for example, an elongated opening that becomes wider toward the center of the cut) is formed.

  The width (average width) of the elongated openings may be, for example, about 0.05 to 5 mm, preferably about 0.1 to 3 mm, and preferably about 0.5 to 2 mm. Moreover, the length (average length) of the elongated openings may be, for example, 0.5 to 20 mm, preferably 1 to 15 mm, and more preferably about 2 to 10 mm.

  In addition, when providing a linear cut | interruption in a reinforcement cloth, the cutting direction of a linear cut | interruption is not specifically limited, However, At least the direction (for example, orthogonal or the direction which cross | intersects the longitudinal direction (belt longitudinal direction in a reinforcement cloth) of a belt) It is preferable that the direction is substantially orthogonal. With such a cutting direction, in particular, when a rib portion is provided in the compressed rubber layer, an opening bent along the rib portion so as to cross the corner portion of the rib portion can be easily formed. That is, in this case, since the opening is made along the corner portion of the rib portion, as shown in FIG. 1, the bent opening portion [the opening portion of a dogleg shape (or bowl shape)] (the elongated opening portion) is formed. It is formed.

  In addition, when the reinforcing cloth is formed of long fibers, the cutting direction of the linear cut may be a direction that crosses at least the orientation direction of the long fibers. By setting it as such a cutting direction, the cutting | disconnection of a long fiber and formation of an opening part can be made to make compatible efficiently.

  In addition, when providing a cut | interruption in a reinforcement cloth previously, as above-mentioned, not all the cut | interruptions necessarily need to form an opening part, and a part of cut | interruptions may remain without opening.

  Although an opening part is not limited, When a compression rubber layer has a rib part, it is preferable to form so that the corner part of a rib part may be crossed. As described above, when a linear cut is opened, a dogleg-shaped opening that crosses the corner can be easily formed.

  There may be one opening, but usually there may be a plurality. The positional relationship between the plurality of openings is not particularly limited, and may be arranged one-dimensionally (for example, a plurality of openings may be arranged linearly at a predetermined interval). From the standpoint of improving the adhesion to the cloth, the reinforcing cloth usually has a plurality of openings extending along the belt longitudinal direction (longitudinal direction of the reinforcing cloth) and the belt width direction (width direction of the reinforcing cloth). There are many cases. The positional relationship between the plurality of openings is not particularly limited, but is arranged in a staggered manner (continuously arranged) from the viewpoint of efficiently forming openings that cross the corners of the ribs. Is preferred.

  As a specific example of forming a plurality of openings using a reinforcing cloth having a linear cut, a reinforcing cloth in which a large number of perforations are formed at predetermined line intervals is used as the reinforcing cloth. Examples thereof include a reinforcing cloth in which a plurality of openings are formed by opening at least a part (particularly perforation crossing the corner portion of the rib portion). Note that the perforation is a line in which cuts such as through holes are arranged in a line at regular intervals, and the fibers (particularly long fibers) constituting the reinforcing cloth are cut by the perforations. The interval between the perforations (line interval) can be appropriately selected according to the distance between the openings described later, but is, for example, 1 to 50 mm, preferably 2 to 40 mm, more preferably 3 to 30 mm (for example, 5 to 15 mm). ), In particular, about 5 to 15 mm.

  Although the space | interval of several opening part is not specifically limited, For example, an average space | interval is 0.1-50 mm (for example, 0.5-45 mm) along a belt longitudinal direction, Preferably it is 1-40 mm (for example, 1.. 5 to 35 mm), more preferably about 2 to 30 mm (for example, 3 to 30 mm), and usually about 5 to 40 mm (for example, 10 to 30 mm).

  The interval between the plurality of openings is 0.1 to 50 mm (for example, 0.3 to 45 mm), preferably 0.5 to 40 mm (for example, 1 to 35 mm), more preferably 1 along the belt width direction. About 5-30 mm (for example, 2-25 mm) may be sufficient and about 1-20 mm (for example, 5-10 mm) may be sufficient normally.

  In addition, the area of the opening (when there are a plurality of openings, the total area thereof) is, for example, 3 to 80 with respect to the entire surface (outer surface or outermost surface) of the reinforcing cloth (or compressed rubber layer). % (Eg 4 to 75%), preferably 5 to 70% (eg 7 to 60%), more preferably 8 to 55% (eg 10 to 50%), especially 20 to 60% (eg 25 -55%, preferably 30-50%). In addition, if the area of the opening is too small, there is a possibility that sufficient adhesion between the compressed rubber layer and the reinforcing cloth cannot be secured, and the area of the opening is too large (or the underlayer is exposed too much). Depending on the material of the underlayer, a part of the exposed underlayer may be separated or scattered when the belt travels.

  Note that the transmission belt of the present invention only needs to include at least the stretched rubber layer, the core wire, the compressed rubber layer, the base layer, and the reinforcing cloth as described above, and further includes other layers as necessary. It may be.

  For example, in the example shown in the figure, the compression rubber layer is directly laminated on the stretch rubber layer, but if necessary, an adhesive for embedding the core wire between the stretch rubber layer and the compression rubber layer. A rubber layer may be laminated (intervened). The same rubber composition as the stretched rubber layer (rubber composition containing a rubber component such as ethylene-α-olefin elastomer) can be used for the adhesive rubber layer. In the rubber composition of the adhesive rubber layer, the same rubber or the same type of rubber as the rubber component of the rubber composition of the stretched rubber layer is often used as the rubber component. 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 stretched rubber layer. The rubber composition of the adhesive rubber layer may further contain an adhesion improver (resorcin-formaldehyde cocondensate, amino resin, etc.). The thickness of the adhesive rubber layer is, for example, about 0.4 to 3.0 mm, preferably about 0.6 to 2.2 mm, and more preferably about 0.8 to 1.4 mm.

  In the present invention, the adhesive rubber layer is usually not provided in many cases.

[Production method of transmission belt]
The power transmission belt of the present invention is not particularly limited, but usually, a method using a mold, for example, a cylindrical drum (or a mold or an inner mold) and an unvulcanized structure composed of the rubber composition for an extended rubber layer. Unvulcanized rubber sheet (compressed rubber layer) comprising a rubber sheet (unvulcanized rubber sheet for forming a stretched rubber layer, rubber sheet for stretched rubber layer), a core wire, and a rubber composition for the compressed rubber layer A sheet for forming an underlayer on an unvulcanized (uncrosslinked) laminated rubber sheet wound with an unvulcanized rubber sheet for forming, and a rubber sheet for a compressed rubber layer (underlayer sheet) ) And a reinforcing fabric (sheet for reinforcing fabric) having a cut (hole) for forming an opening, and a winding step for obtaining an unvulcanized rubber sleeve (laminated sheet for belt), and this winding step The unvulcanized belt sleeve obtained in Pressed against the mold (or the outer mold or vulcanized) with (pressed by the mold), by a method comprising a vulcanization molding step of molding heated to vulcanization (or crosslinking) can be prepared.

  In the present invention, the transmission belt as described above can be obtained even by a method using a mold (and a vulcanization mold) that does not require polishing.

  Although it does not specifically limit as a method (or means) for vulcanization molding by pressing against a mold, for example, a cylindrical molding drum having a flexible jacket (bladder) is used as a cylindrical drum. On the flexible jacket, the winding process of winding various sheets, the core wire and the reinforcing cloth in the above order is performed, the flexible jacket is expanded, and the unvulcanized belt sleeve is formed into a mold (outer mold). While pressing, vulcanization molding may be performed under heating. In addition, when forming the compression rubber layer which has a rib part, it has a metal mold | die (or outer mold | type, specifically, the groove-shaped marking corresponding to a rib part) as a metal mold | die (outer mold). A rib part (a plurality of rib parts) is formed by pressing against a mold or an outer mold.

  In the winding step, the sheet for forming the underlayer may be a sheet (or film) constituted by components constituting the underlayer, or a fabric (nonwoven fabric or the like) formed by components constituting the underlayer. ) Etc. may be used. For example, the base layer may be formed by using a fabric formed of a thermoplastic resin constituting the base layer and melting it in the vulcanization molding step.

  In the winding step, a reinforcing cloth having a cut (hole) for forming the opening is used as the reinforcing cloth. Such a cut may be the opening itself, or may be a cut (for example, a linear cut) that can be opened by pressing in the vulcanization molding process to form the opening. In particular, when the rib portion is formed in the compressed rubber layer, as described above, the opening may be formed by opening a cut across at least the corner portion of the rib portion.

  For example, as described above, when a reinforcing cloth having a perforation is used, a part of the perforation is opened or cleaved to form an opening (elongated opening). Moreover, when providing a rib part in a compression rubber layer, the perforation which crosses the corner part of a rib part mainly tears, and an opening part is formed.

  In the winding step, the base layer sheet and the reinforcing cloth may be wound individually, or a composite sheet in which the base layer sheet and the reinforcing cloth are laminated in advance may be wound.

  The vulcanization molding step may be usually performed under heating or heating, and the heating temperature may be, for example, 120 to 220 ° C, preferably 130 to 200 ° C, more preferably about 150 to 180 ° C. .

  In such a vulcanization molding step, when the base layer sheet is made of a thermoplastic resin (specifically, a thermoplastic resin having a melting point or softening point lower than the vulcanization temperature of the stretched rubber layer) The thermoplastic resin is melted or melted to form an underlayer [film-like (or smooth) skin layer]. Then, the melt of the thermoplastic resin flows in (or enters) through the opening of the reinforcing cloth, and a belt in which the base layer has entered into the opening is obtained. Note that the degree of opening can be adjusted by adjusting the vulcanization temperature, pressure, and the like.

  In the vulcanization molding process, the molding pressure is efficiently transmitted to the stretched rubber layer 4 (or the unvulcanized rubber sheet) while efficiently degassing (gas degassing) generated in the molding process in the mold. By making (or propagating), it is possible to efficiently obtain a belt in which a core wire is embedded in such a stretched rubber layer.

  In this way, a belt sleeve (particularly a belt sleeve having a rib portion) is obtained, and then the individual vulcanized sleeve (V-ribbed belt or the like) can be finished by cutting the vulcanized sleeve into a predetermined width and cutting it.

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

(Friction coefficient measurement test)
For the measurement of the friction coefficient, a drive pulley (Dr.) with a diameter of 121.6 mm, an idler pulley (IDL.1) with a diameter of 76.2 mm, an idler pulley (IDL.2) with a diameter of 61.0 mm, a diameter of 76.2 mm A testing machine having a layout shown in FIG. 5 was used in which an idler pulley (IDL.3), an idler pulley (IDL.4) having a diameter of 77.0 mm, and a driven pulley (Dn.) Having a diameter of 121.6 mm were sequentially arranged. That is, the V-ribbed belt produced on each pulley of the test machine is hung, and during normal running (DRY), the rotational speed of the drive pulley is 400 rpm and the belt winding angle around the driven pulley is 20 ° under room temperature conditions. Drive the belt while applying a constant load (180N / 6Rib), increasing the torque of the driven pulley to 0 to 20Nm, and the belt sliding speed with respect to the driven pulley becomes maximum (100% slip). From the pulley torque value, the friction coefficient μ was determined using the following equation.

μ = ln (T1 / T2) / α
Here, T1 is the tension on the tension side, T2 is the tension on the loose side, and α is the belt winding angle around the driven pulley, which can be obtained by the following equations, respectively.

T1 = T2 + Dn. Torque (kgf · m) / (121.6 / 2000)
T2 = 180 (N / 6 Rib) (where Rib means a rib)
α = π / 9 (rad) (where rad means radians)
In addition, the friction coefficient (WET) during water injection is measured, as shown in the layout of FIG. 6, the rotational speed of the driving pulley is 800 rpm, the belt winding angle around the driven pulley is 45 ° (α = π / 4), The same test was performed using the same equation as in the normal running, except that 300 ml of water was continuously poured near the inlet of the driven pulley for 1 minute.

(Bend fatigue test)
As shown in FIG. 7, the bending fatigue resistance test (reverse bending high-temperature low-tension bending test) consists of a driving pulley 24 having a diameter of 120 mm, an idler pulley 25 having a diameter of 85 mm, a driven pulley 26 having a diameter of 120 mm, and a tension pulley 27 having a diameter of 55 mm. The test was performed using the placed testing machine. That is, the V-ribbed belt B produced on each of the pulleys 24 to 27 is hung, and the winding angle of the V-ribbed belt B around the tension pulley 27 is 90 °, the winding angle around the idler pulley 25 is 120 °, the ambient temperature is 120 ° C., and the driving pulley 24 The V-ribbed belt B was run by applying a load to the tension pulley 27 and a load 12 PS to the driven pulley 26 under the test conditions of 4900 rpm and a belt tension of 559 N / 3 rib. And the running time when the first crack was confirmed in the rib part of V ribbed belt B was made into crack generation time, and it was set as a measure of bending fatigue resistance. Moreover, in order to see the adhesion degree of a rib part and a long-fiber nonwoven fabric, the peeling state of the long-fiber nonwoven fabric was observed with the naked eye on the rib part surface in the said belt running time (150 hours).

(Surface occupancy rate of opening)
After cutting the rib groove (valley) of the manufactured V-ribbed belt along the belt length direction and taking out one rib portion, the sample is further cut into a length of 10 mm in a direction perpendicular to the belt length direction. Was made. The surface of the rib part of the cut sample is photographed with a microscope, and the area of the opening part (particularly present in the corner part at the end of the rib part) formed by opening the cuts provided in the nonwoven fabric in advance is obtained. The surface occupancy rate of the opening was calculated from the surface area.

(material)
EPDM polymer: “IP3640” manufactured by DuPont Dowelasmer Japan Co., Ltd., Mooney viscosity 40 (100 ° C.)
Carbon HAF: “Seast 3” manufactured by Tokai Carbon Co., Ltd.
Anti-aging agent: “Nonflex OD3” manufactured by Seiko Chemical Co., Ltd.
Nylon milled fiber: nylon 66, fiber length approx. 0.5mm
Organic peroxide: “Parkadox 14RP” manufactured by Kayaku Akzo Corporation
Ether S plasticizer: “RS-700” manufactured by Adeka Co., Ltd., SP value 8.5, viscosity 30 cps (20 ° C.)
Solid lubricant: artificial graphite powder “AT No. 20”, average particle size 8 μm
Underlayer sheet: High-density polyethylene (HDPE) film, Tamapoly Co., Ltd. “Multitron”, thickness 40 μm
Nonwoven fabric: Spunbond nonwoven fabric made of polypropylene (PP) long fibers, “WJ55P100” manufactured by Venus Paper Co., Ltd., melting point of about 165 ° C., basis weight 30 g / m ²
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.

Examples 1 to 4 and Comparative Example 1
(Rubber sheet for forming the stretched rubber layer)
The rubber composition shown in Table 1 was kneaded with a Banbury mixer and rolled with a calender roll to prepare a rubber sheet with a thickness of 0.8 mm for forming an extension layer.

(Rubber sheet for forming a compressed rubber layer)
The rubber composition shown in Table 2 was kneaded with a Banbury mixer and rolled with a calender roll to prepare a rubber sheet with a thickness of 2.5 mm for forming a compressed rubber layer.

(Manufacture of belts)
As shown in FIG. 2, a rubber sheet 16a for forming an elastic rubber layer is wound around the outer periphery of a bladder 15 of a mold (cylindrical drum or inner mold) 14 having an air supply port 23 and a top plate 22a. After winding the core wire 4 in a spiral shape around the outer peripheral surface of the rubber sheet 16a, a rubber sheet 16b for forming a compressed rubber layer (or rib portion) was further wound around the core wire 4. Furthermore, a sheet for the base layer (HDPE film) is wound around the outer peripheral surface of the rubber sheet 16b in advance, and further, a nonwoven fabric is wound on the ply, and the ends are overlapped by 20 mm, followed by thermocompression bonding with an iron. The belt sleeve 17 was attached.

  In the comparative example, the raw material nonwoven fabric was used as it was. Further, in the embodiment, as shown in FIG. 8, a cutter is used to further increase the number of predetermined line intervals (5 mm in the first embodiment, 10 mm in the second embodiment, 15 mm in the third embodiment, and 20 mm in the fourth embodiment). The perforated non-woven fabric 8 obtained by cutting the long fibers is continuously inserted from one end of the non-woven fabric to the other end of the perforated 8B (the interval between the perforation through holes is 0.2 mm). Using. The cut direction (perforation direction) of the cut was a direction orthogonal to the orientation direction of the long fibers.

  Further, as shown in FIG. 3, the mold 14 around which the belt sleeve 17 is wound is set in the vulcanizing mold 18 and heated by a heating / cooling jacket 35 having heating / cooling medium introduction ports 36, 37. 4, the bladder 15 was expanded and vulcanized by pressing the belt sleeve 17 against the inner peripheral surface of the vulcanizing mold 18 and applying pressure. The vulcanization conditions were set at 160 ° C., 1 MPa, and 20 minutes. At this time, the concave and convex portion 41 for molding of the vulcanizing mold 18 bites into the belt sleeve 17 from the outer periphery, so that the groove 26 is formed on the outer periphery of the belt sleeve 17.

  Next, the mold 14 was extracted from the vulcanization mold 18, and the vulcanization belt sleeve remaining in the vulcanization mold 18 was cooled by the heating / cooling jacket 35, and then the vulcanization belt sleeve was removed from the vulcanization mold 18. And this V-ribbed belt was obtained by cut | disconnecting this vulcanization belt sleeve so that it may cut with a cutter.

  The V-ribbed belts obtained in Examples 1 to 4 had the structure shown in FIG. That is, the rib part of the obtained V-ribbed belt had a large number of openings formed by openings formed in advance on the surface thereof. Many of the openings had a bent shape that crossed the corners of the ribs. Further, it was confirmed that a part of the melted underlayer had entered the opening. Further, when a cross section of the obtained V-ribbed belt was photographed with a microscope, the core wire 3 was embedded in the stretched rubber layer 5 containing short fibers [or stretched rubber containing short fibers, as shown in FIG. The layer 5 penetrated between the core wires 3, that is, penetrated toward the compressed rubber layer 6 side beyond the center line L connecting the centers of the core wires 3].

(Evaluation of belt)
The evaluation of the manufactured V-ribbed belt is shown in Table 3 together with the perforation line interval in the nonwoven fabric used.

  As is clear from the results in Table 3, in the belt of the example, the difference in friction coefficient between DRY and WET was small. Therefore, the occurrence of abnormal noise can be suppressed as compared with the belt of the comparative example. Further, cracks were less likely to occur as compared with the belt of the comparative example. In particular, such a tendency was conspicuous as the surface occupancy ratio of the opening was larger.

  The power transmission belt of the present invention can be used for various power transmission belts (particularly, molding-less belts), for example, friction power transmission belts such as V-ribbed belts, V-belts, low-edge V-belts, and flat belts. This is useful for V-ribbed belts and the like in which the production process is complicated.

DESCRIPTION OF SYMBOLS 1 ... V ribbed belt 2 ... Core wire 3 ... Short fiber 4 ... Stretch layer 5 ... Compression rubber layer 6 ... Rib part 6A ... Corner part of rib part 7 ... Underlayer 8 ... Reinforcement cloth 8A ... Opening part 8B ... Perforation L ... A line connecting the centers of the core 2

Claims (17)

A power transmission belt comprising at least a stretched rubber layer, a core wire embedded along the longitudinal direction of the belt, and a compressed rubber layer,
Furthermore, a base layer laminated on the compressed rubber layer, and a reinforcing cloth laminated on the base layer and having an opening,
The reinforcing cloth has a linear cut, and the opening is formed by the opening of the linear cut; and
Transmission belt the underlying layer through the opening is exposed.   The power transmission belt according to claim 1, wherein the underlayer is formed of a thermoplastic resin.   The power transmission belt according to claim 1 or 2, wherein the underlayer is formed of an olefin resin.   The base layer is formed of a thermoplastic resin having a melting point or a softening point equal to or lower than the vulcanization temperature of the stretched rubber layer, and a melt of the thermoplastic resin enters from the opening. Power transmission belt.   The transmission belt according to any one of claims 1 to 4, wherein the average thickness of the underlayer is 1 to 500 µm.   The transmission belt according to any one of claims 1 to 5, wherein the reinforcing cloth is a non-woven fabric formed of long fibers.   The transmission belt according to any one of claims 1 to 6, wherein the reinforcing cloth is a spunbonded nonwoven fabric composed of propylene fibers. A reinforcing fabric is formed by long fiber nonwoven fabric, according to claim 1 to 7 long fibers are oriented along the longitudinal direction of the belt, and the cutting direction of the linear cut is a direction intersecting the longitudinal direction of the belt The power transmission belt according to any one of the above. The transmission belt according to any one of claims 1 to 8 , wherein the compression rubber layer has a rib portion extending in a belt longitudinal direction, and the reinforcing cloth forms an opening bent so as to cross a corner portion of the rib portion. . The transmission belt according to any one of claims 1 to 9 , wherein the reinforcing cloth has a plurality of openings extending along the belt longitudinal direction and the belt width direction. The power transmission belt according to any one of claims 1 to 10 , wherein the reinforcing cloth has a plurality of openings formed at intervals of an average of 5 to 40 mm in the belt longitudinal direction. The transmission belt according to any one of 1 to 11 , wherein the area of the opening is 10 to 50% of the entire surface of the reinforcing cloth. The transmission belt according to any one of claims 1 to 12 , wherein the compression rubber layer is a V-ribbed belt having a plurality of rib portions extending in the belt longitudinal direction. On an unvulcanized laminated rubber sheet in which an unvulcanized rubber sheet for forming a stretched rubber layer, a core wire, and an unvulcanized rubber sheet for forming a compressed rubber layer are wound around a cylindrical drum, Furthermore, a winding process for obtaining a non-vulcanized rubber sleeve by winding a reinforcing cloth having a sheet for forming an underlayer and a cut line for forming an opening, and an unvulcanized product obtained in this winding process along with pressing the belt sleeve in a mold, a manufacturing method of the driving belt according to any one of claims 1 to 13, heated and a vulcanization molding step of molding vulcanization. The manufacturing method according to claim 14 , wherein, in the vulcanization molding step, an opening is formed by opening a cut by pressing. In vulcanizing process, using a mold corresponding to the rib portion, to form a compression rubber layer having a rib extending in the longitudinal direction of the belt, according to claim 15, wherein for opening the cut across the corner portion of the rib portion Production method. The sheet for forming the underlayer is formed of a thermoplastic resin having a melting point or a softening point equal to or lower than the vulcanization temperature of the stretch rubber layer, and is heated by pressing at the vulcanization molding step and at the vulcanization temperature. The manufacturing method according to any one of claims 14 to 16 , wherein an underlayer is formed by melting the resin, and a molten thermoplastic resin is infiltrated from the opening.

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