JP5869332B2 - Transmission belt - Google Patents

Description

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

  In a V-ribbed belt used for power transmission, a twisted cord formed of fibers is embedded as a core wire in a main body formed of a rubber composition. A twist cord is a member that bears most of the belt tension, and its characteristics are determined by a combination of fiber type, number of twists, twist direction, fineness, and the like. V-ribbed belts having such a structure are widely used for power transmission for driving auxiliary equipment such as automobile air compressors and alternators. In order to attach a transmission belt to these drive systems, it is common to move the pulley in a direction that reduces the distance between the shafts, hang the transmission belt, and then return the pulley to its original position to apply tension. there were.

  However, in recent years, due to the demand for a reduction in installation space accompanying the downsizing of the apparatus, there are many cases where it is used in a layout in which the distance between the axes is fixed. In this layout, it is necessary to attach the belt while the distance between the shafts is fixed, but after the attachment, it is necessary to maintain a tension that prevents the belt from slipping. Therefore, the belt circumference is shortened with respect to the layout circumference, the belt is stretched (for example, 1 to 5%), and the belt is attached to the pulley to apply tension. As this type of belt, a belt having a low tensile elastic modulus is used because it is necessary to stretch the belt at the time of attachment.

  Japanese Patent Application Publication No. 2004-532959 (Patent Document 1) discloses a low-elasticity belt for automobiles in which a polyamide 66 twisted cord is used and the tensile elastic modulus of the belt is set to 7000 to 10000 N / mm / mm. This document states that the belt can be attached to the pulley by stretching and can maintain the desired tension throughout the design life of the drive. In addition, since the belt has a low tensile elastic modulus, the belt can be easily attached, and an auxiliary machine (for example, a water pump) having a relatively small load can be driven.

  However, in order to drive an auxiliary machine such as an alternator, it is necessary to increase the tensile elastic modulus of the belt, and the low elastic belt of Patent Document 1 has a large drop in tension (especially high temperature such as 100 ° C.). A slip occurred. Therefore, a V-ribbed belt has been proposed in which a tensile cord is improved by using a twisted cord in which a low elastic fiber and a high elastic fiber are combined as a core wire.

  Japanese Patent Application Laid-Open No. 2010-106898 (Patent Document 2) discloses a combination of a low-elasticity polyamide fiber and a high-elasticity polyester fiber as a core, and a belt elastic modulus of 15000 to 45000 N / mm / mm. A V-ribbed belt is disclosed. According to this document, the V-ribbed belt suppresses the jumping of the core wire and the belt disassembly and is a low-elasticity type V-ribbed belt. It is described that the machine can be transmitted. Furthermore, in this document, 930 dtex polyamide 66 fiber and 1110 dtex polyethylene terephthalate (PET) fiber are mixed and twisted at a base twist number of 22.8 times / 10 cm to form a strand, and these three strands are the number of top twists. A cord with a 9.9 twist / 10 cm twist is manufactured.

  Japanese Patent Laid-Open No. 2003-194152 (Patent Document 3) discloses a multifilament yarn in which a core wire is formed of a polyamide fiber and a multifilament yarn formed of a PET fiber to form a lasso. A V-ribbed belt is disclosed which is a twisted cord in which a plurality of cords are bundled and twisted in the direction opposite to the lower twisting direction, and the stress required to stretch 2% is 250 to 350 N / rib. In this document, a 940 dtex multifilament yarn made of polyamide 66 and a 1220 dtex multifilament yarn made of PET are mixed and twisted at a final twist number of 202 times / m to form a lasso. A V-ribbed belt is prepared which includes a core wire having a top twist coefficient of 3.0.

  By the way, when the belt is used in a multi-axis layout (for example, the number of pulleys is 3 or more), the belt is wound around the pulley while being bent. For this reason, the core wire embedded in the belt body is required to have bending fatigue resistance in addition to the tensile elastic modulus and tension maintainability. If the resistance to bending fatigue is insufficient, the core wire may be cut early during belt running, and the belt may have a lifetime.

  However, these V-ribbed belts do not have sufficient bending fatigue resistance. For example, in a multi-axis layout, the core wire tends to be cut early.

Japanese translation of PCT publication No. 2004-532959 (claim 1, paragraph [0007]) JP 2010-106898 A (claims, paragraph [0006], examples) JP-A-2003-194152 (Claim 1, Example)

  Accordingly, an object of the present invention is to provide a transmission belt that can be easily attached to a pulley, maintain belt tension even in a high load layout, and improve bending fatigue resistance.

  Another object of the present invention is to provide a transmission belt capable of adjusting the tensile elastic modulus of the belt according to the load.

  Still another object of the present invention is to provide a transmission belt that can suppress the cutting of the core wire even in a multiple layout.

  As a result of intensive studies on the causes of the V-ribbed belts in Patent Documents 2 and 3 that cannot improve the bending fatigue resistance, the following causes have been found. That is, since the V-ribbed belts of Patent Documents 2 and 3 combine a low elastic yarn and a high elastic yarn as a core wire, when the belt is tensioned, the tension is equal between the low elastic yarn and the high elastic yarn. The high elastic yarn that is not supported by the wire and has a small elongation is mainly burdened. Therefore, the high elastic yarn is subjected to strong bending fatigue, and fatigue is promoted at this portion, which leads to early cutting of the core wire. Furthermore, in the V-ribbed belt of Patent Document 2, the upper twist coefficient is low, and the bending fatigue resistance of the core wire is low.

  Therefore, as a result of intensive studies to achieve the above-mentioned problems, the present inventor has adjusted the fiber type, the number of twists, the twist direction, the fineness, etc. of the mixed twist yarn used as the core wire (particularly the core wire). Approximate the tensile stress of polyester multifilament yarn and polyamide multifilament yarn twisted together as a mixed twisted yarn), and adjust the upper twist coefficient and belt elastic modulus of the mixed twisted yarn to a specific range to attach the belt to the pulley Has been found to be easy and can improve the bending fatigue resistance, and the present invention has been completed.

  That is, the transmission belt of the present invention includes a belt main body and a core wire extending in the belt longitudinal direction and embedded in the belt main body. The core wire is a twisted yarn cord obtained by twisting a plurality of yarns including a strand, and the strand includes a polyester multifilament yarn including a polyester fiber and a polyamide multifilament yarn including a polyamide fiber. Including a lower twisted yarn that is a mixed twisted yarn. The twisting coefficient of the twisted yarn cord is 3-7. The transmission belt has a tensile elastic modulus of 20 to 35 N / (mm ·%).

  In the transmission belt of the present invention, the ratio between the 5% stretch stress of the polyester multifilament yarn subjected to 80 times / m twist and the 5% stretch stress of the polyamide multifilament yarn subjected to 80 times / m twist. The former / the latter may be 1/2 to 2/1. The polyester multifilament yarn having a twist of 80 turns / m may have a 5% elongation stress of 1.4 to 2.2 cN / dtex, and the polyamide multifilament yarn having a twist of 80 turns / m The 5% tensile stress may be 1.0 to 1.8 cN / dtex.

  In the power transmission belt of the present invention, the ratio between the 10% elongation stress of the polyester multifilament yarn subjected to 80 times / m twist and the 10% elongation stress of the polyamide multifilament yarn subjected to 80 times / m twist. The former / the latter may be 1/3 to 1.2 / 1. The polyester-based multifilament yarn having a twist of 80 turns / m may have a 10% elongation stress of 3.3 to 4.1 cN / dtex. The 10% tensile stress may be 3.5 to 4.3 cN / dtex.

  In the transmission belt of the present invention, the dry heat shrinkage rate of the polyester multifilament yarn after treatment at 150 ° C. for 30 minutes may be 3% or less. The polyester multifilament yarn may include a polyalkylene arylate fiber, and the polyamide multifilament yarn may include an aliphatic polyamide fiber.

  The present invention is a twisted yarn cord including a belt main body and a core wire extending in the belt longitudinal direction and embedded in the belt main body, and the core wire is an upper twist of a plurality of yarns including a strand. The transmission belt includes a lower twisted yarn in which a plurality of yarns including a polyester-based multifilament yarn including a polyester fiber and a polyamide-based multifilament yarn including a polyamide fiber are mixed and twisted, and an upper twist coefficient of the twisted yarn cord And a method for improving the bending fatigue resistance of the transmission belt by adjusting the tensile elastic modulus of the transmission belt to 20 to 35 N / (mm ·%). In this method, the ratio of the 5% elongation stress of the polyester multifilament yarn subjected to 80 times / m twist to the 5% elongation stress of the polyamide multifilament yarn subjected to 80 times / m twist is defined as the former. / The latter may be adjusted to 1/2 to 2/1.

  In the present invention, in the transmission belt, the fiber type, the number of twists, the twist direction, the fineness, etc. of the mixed twist yarn used as the core wire are adjusted, and the upper twist coefficient and belt elastic modulus of the mixed twist yarn are adjusted to a specific range. The belt can be easily attached to the pulley, the belt tension can be maintained even in a high load layout, and the bending fatigue resistance can be improved. In particular, by approximating the tensile stress of polyester-based multifilament yarn and polyamide-based multifilament yarn twisted as a mixed yarn of core wires, the bending fatigue resistance can be further improved. Can be cut. Further, the tensile elastic modulus of the belt can be adjusted according to the load. Therefore, product design is easy and it can cope with both low load and high load.

FIG. 1 is a schematic cross-sectional view showing an example of a transmission belt of the present invention. FIG. 2 is a model diagram showing an embodiment of a twisted configuration of the core wire. FIG. 3 is a schematic diagram showing a measurement method for evaluating the bending fatigue resistance of the core wire in the example. FIG. 4 is a schematic diagram for explaining a biaxial running test in the embodiment. FIG. 5 is a graph showing a stress-strain curve of the raw yarn used in the examples.

[Power transmission belt]
The transmission belt of the present invention includes a belt body and a core wire embedded in the belt body and extending in the belt longitudinal direction. FIG. 1 is a schematic sectional view showing a V-ribbed belt which is an example of a power transmission belt of the present invention.

  In this example, the V-ribbed belt has rib portions 9 (four rows in the drawing) extending in a plurality of rows along the longitudinal direction of the belt on the inner peripheral surface (lower surface) 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 has an inverted trapezoidal shape (V-shaped cross section). The V-ribbed belt has a laminated structure, and from the inner peripheral side to the outer peripheral side of the belt main body, the compression layer 2 having the rib portion 9, the adhesive layer 6 in which the core wire 1 is embedded in the belt longitudinal direction, the stretch Layers 8 are sequentially stacked. The compressed layer 2 includes a plurality of short fibers 10 oriented in the belt width direction.

(Core)
The core wire is a twisted cord obtained by twisting a plurality of yarns including a strand (bottom twisted yarn). The strand includes a lower twisted yarn (mixed twisted rope) obtained by blending a plurality of yarns including a polyester multifilament yarn including a polyester fiber and a polyamide multifilament yarn including a polyamide fiber.

  Polyester-based multifilament yarns only need to contain monofilament yarns (single yarns) of polyester fibers, and may be multifilament yarns that combine multiple types of single yarns, but usually the same single yarn (polyester fibers) ) Is a multifilament yarn.

As the polyester fiber, a polyalkylene arylate fiber having a main constituent unit of C _2-4 alkylene arylate such as ethylene terephthalate, butylene terephthalate, ethylene-2,6-naphthalate is usually used. Examples of the polyalkylene arylate fiber include polyethylene terephthalate (PET) fiber, polytrimethylene terephthalate fiber, polybutylene terephthalate fiber, and polyethylene naphthalate fiber. These polyester fibers can be used alone or in combination of two or more.

  Of these polyester fibers, PET fibers are preferred. In addition to the ethylene terephthalate unit, the PET resin constituting the PET fiber includes other dicarboxylic acids (for example, isophthalic acid, naphthalene-2,6-dicarboxylic acid, phthalic acid, 4,4′-diphenyldicarboxylic acid, bis (Carboxyphenyl) ethane, 5-sodium sulfoisophthalic acid, etc.) and diols (for example, diethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,6-hexanediol, neopentyl glycol, cyclohexane-1, 4-dimethanol, polyethylene glycol, polytetramethylene glycol, and the like) may be included at a ratio of about 20 mol% or less.

  The average fineness of the polyester multifilament yarn is, for example, about 200 to 3000 dtex, preferably about 300 to 2500 dtex, and more preferably about 500 to 2000 dtex (particularly 800 to 1500 dtex). The number of yarns (single yarn) constituting the multifilament yarn is, for example, about 100 to 600, preferably about 200 to 550, and more preferably about 250 to 500. The average fineness of the single yarn is, for example, 1 It is about 10 to 10 dtex, preferably about 2 to 8 dtex, more preferably about 3 to 7 dtex.

  In the present invention, the polyester-based multifilament yarn is preferably a low-elasticity polyester-based fiber. By using low-elasticity polyester-based fibers, it can be approximated to the elastic modulus of polyamide-based fibers, the bending fatigue resistance can be improved, and attachment to a pulley can be facilitated.

  Specifically, the 5% stretch stress (stress in the low stretch range) when a polyester multifilament yarn twisted at 80 turns / m is pulled can be selected from a range of about 1.2 to 3 cN / dtex. 1.4 to 2.2 cN / dtex, preferably 1.5 to 2.1 cN / dtex, more preferably 1.6 to 2 cN / dtex (especially 1.7 to 1.9 cN / dtex). By adjusting the 5% elongation stress within the above range, the elastic modulus of the polyester multifilament yarn in the low elongation region can be lowered, and attachment to the pulley can be facilitated. If the 5% elongation stress is too low, the tension drop (stress relaxation) at the time of belt attachment becomes large, and conversely, if it is too high, attachment to the pulley becomes difficult.

  In particular, by approximating the ratio of the 5% elongation stress of the polyester multifilament yarn to the 5% elongation stress of the polyamide multifilament yarn described later, the polyester multifilament yarn This tension can be appropriately borne by the polyamide-based multifilament yarn, and the bending fatigue resistance of the core wire can be improved. Specifically, the ratio between the 5% elongation stress of the polyester multifilament yarn and the 5% elongation stress of the polyamide multifilament yarn is, for example, the former / the latter = 1/2 to 2/1, preferably 1 / It is about 1.5 to 1.8 / 1, more preferably about 1/1 to 1.5 / 1 (particularly 1.1 / 1 to 1.3 / 1). If the ratio of both is out of this range, the balance between the polyester-based multifilament yarn and the polyamide-based multifilament yarn is deteriorated, and the bending fatigue resistance of the core wire is lowered.

  Further, the 10% stretch stress (stress in the intermediate stretch region) when the polyester-based multifilament yarn twisted at 80 turns / m is pulled can be selected from a range of about 3 to 5 cN / dtex, for example, 3.3. It is about -4.1 cN / dtex, preferably about 3.4-4 cN / dtex, more preferably about 3.5-3.9 cN / dtex (particularly 3.6-3.8 cN / dtex). By adjusting the 10% tensile stress to the above range, the elastic modulus in the intermediate stretch region of the polyester multifilament yarn can be lowered, the elastic modulus can be increased moderately, and the belt tension can be reduced even in a heavy-load layout. Can be suppressed. If the 10% elongation stress is too low, the tension during running will decrease, and if it is too high, it will be difficult to attach to the pulley.

  In particular, the ratio of the 10% stretch stress of the polyester multifilament yarn subjected to 80 times / m twist and the 10% stretch stress of the polyamide multifilament yarn applied 80 times / m is, for example, the former. / Latter = 1/3 to 1.2 / 1, preferably 1/2 to 1.1 / 1, more preferably 1 / 1.5-1 to 1/1 (particularly 1 / 1.2 to 1/1). It is. If the ratio of both is out of this range, the balance between the polyester-based multifilament yarn and the polyami-based multifilament yarn is deteriorated, and the bending fatigue resistance of the cord may be lowered.

  The breaking strength of the polyester multifilament yarn may be, for example, about 3 to 10 cN / dtex, preferably about 5 to 9 cN / dtex, and more preferably about 6 to 8 cN / dtex. The breaking elongation of the polyester multifilament yarn may be 15% or more, for example, 15 to 50%, preferably 16 to 30%, more preferably about 17 to 20%.

  In this specification, in detail, the tensile stress, breaking strength and breaking elongation of the multifilament yarn can be measured by the methods described in the examples described later.

  Polyester multifilament yarns having such tensile elasticity (especially tensile stress) can be obtained by adjusting the proportion of copolymerizable monomer of polyethylene terephthalate fiber, spinning conditions, etc. A multifilament yarn having a reduced tensile stress may be prepared by controlling the sheath orientation and reducing the crystallinity.

  The dry heat shrinkage rate of the polyester-based multifilament yarn after treatment at 150 ° C. for 30 minutes may be 3% or less from the viewpoint of improving the dimensional stability of the belt, for example, 2.8% or less, preferably It may be 2.6% or less (for example, 2.0 to 2.6%), more preferably 2.5% or less (for example, 2.1 to 2.5%). Polyamide fibers (especially aliphatic polyamide fibers) have large dimensional changes (especially high humidity dimensional changes), but the dry heat shrinkage of polyester multifilament yarns should be adjusted to the above range (especially 2.6% or less). Thereby, the dimensional change of a core wire can be suppressed. If the dry heat shrinkage ratio is too large, the dimensional change of the belt becomes large. The lower the dry heat shrinkage rate, the better. However, it is difficult to produce a polyester fiber of less than 2.0%.

  In this specification, in detail, the dry heat shrinkage of the multifilament yarn can be measured by the method described in Examples described later.

  Polyamide-based multifilament yarns only need to contain a single yarn of polyamide fiber, and may be a multifilament yarn that is a combination of multiple types of single yarns, but are usually formed from the same single yarn (polyamide fiber). Multifilament yarn.

  Examples of polyamide fibers include polyamide 6, polyamide 46, polyamide 66, polyamide 610, polyamide 10, polyamide 11, polyamide 12, polyamide 6-12, and other aliphatic polyamides and copolymers thereof, aromatic dicarboxylic acids and aliphatics. And semi-aromatic polyamide synthesized from diamine. These polyamide fibers can be used alone or in combination of two or more.

  Among these polyamide fibers, aliphatic polyamide fibers are preferable from the viewpoint of toughness, etc., and have a high melting point of 230 ° C. or higher (for example, 240 to 240 ° C.) because the belt tension can be maintained even at a high temperature such as 100 ° C. Aliphatic polyamide fibers (for example, polyamide 66 fibers, polyamide 46 fibers, etc.) of about 300 ° C. are particularly preferred.

  The average fineness of the polyamide-based multifilament yarn is, for example, about 200 to 3000 dtex, preferably about 300 to 2500 dtex, more preferably about 500 to 2000 dtex (particularly 800 to 1500 dtex). The number of single yarns is, for example, about 100 to 600, preferably about 200 to 550, more preferably about 250 to 500, and the average fineness of the single yarn is, for example, 1 to 10 dtex, preferably 2 to 8 dtex, More preferably, it is about 3 to 7 dtex.

  The 5% stretch stress (stress in the low stretch region) when the polyamide-based multifilament yarn twisted at 80 turns / m is pulled can be selected from a range of about 0.5 to 2.5 cN / dtex. It is about 0.0 to 1.8 cN / dtex, preferably 1.1 to 1.9 cN / dtex, more preferably about 1.2 to 1.8 cN / dtex (particularly 1.3 to 1.6 cN / dtex).

  The 10% stretch stress (stress in the intermediate stretch range) when a polyamide-based multifilament yarn with a twist of 80 turns / m is pulled can be selected from a range of about 3 to 5 cN / dtex, for example, 3.5 to 4 It is about 3 cN / dtex, preferably 3.6 to 4.2 cN / dtex, more preferably about 3.7 to 4.1 cN / dtex (particularly 3.8 to 4.0 cN / dtex).

  The mixed stranded rope only needs to contain the polyester multifilament yarn and the polyamide multifilament yarn, and may further contain other fibers. Examples of other fibers include natural fibers (cotton, hemp, etc.), recycled fibers (rayon, acetate, etc.), synthetic fibers [polyolefin fibers such as polyethylene and polypropylene, styrene fibers such as polystyrene, fluorine such as polyfluoroethylene, etc. Fibers, acrylic fibers, vinyl alcohol fibers such as polyvinyl alcohol, wholly aromatic polyester fibers, wholly aromatic polyamide fibers (aramid fibers), PBO (poly-p-phenylenebenzobisoxazole) fibers, etc.], inorganic fibers ( Carbon fiber, glass fiber, etc.). These other fibers can be used alone or in combination of two or more. Of these other fibers, aromatic polyester fibers, aramid fibers, PBO fibers, carbon fibers, glass fibers and the like are widely used.

  The mixed stranded rope only needs to contain one polyester multifilament yarn and one polyamide multifilament yarn, for example, a plurality of polyester multifilament yarns and / or a plurality of polyamide multifilament yarns, and others. The number of fibers is not limited, but usually one polyester multifilament yarn and one polyamide multifilament yarn are twisted together to form a lower twisted yarn (mixed twisted rope).

  The twisted cord (upper twisted yarn) only needs to contain the mixed twisted rope as the lower twisted yarn, and the number of twisting steps is not particularly limited, and is not limited to the upper twisted yarn obtained by twisting the lower twisted yarn, for example, the lower twisted, A plurality of twists may be performed in the order of twist and top twist. Of these, an upper twisted yarn obtained by twisting a lower twisted yarn is preferable from the standpoint of convenience.

  In the twisted yarn cord, the twist direction of the lower twist (or medium twist) and the upper twist is not particularly limited, and may be various twists in which the twist directions of the lower twist and the upper twist are opposite to each other. But you can. Of these, twisting is preferred because the twisting of the upper twist hardly occurs and the twist is stable.

  In addition to the mixed-twisted rope, the yarn for top twisting (or medium-twisting) includes a strand made by twisting polyester multifilament yarns, a strand made by twisting polyamide multifilament yarns, Fibers and the like may be included. Among these, it is preferable to combine with a strand that twists polyamide-based multifilament yarns from the viewpoint that appropriate belt elasticity can be imparted.

  In the entire twisted yarn cord (upper twisted yarn), the number of lower twisted yarns (or medium twisted yarns) may be two or more, for example, 2 to 8, preferably 2 to 7, more preferably 2 to 6 (particularly 3 to 5), and usually three.

  The ratio of the number of polyester multifilament yarns and polyamide multifilament yarns in the entire twisted cord (upper twisted yarn) can provide appropriate belt elasticity and can be used in high-load layouts without impairing belt attachment. The former / the latter can be selected from the range of about 4: 1 to 1:10. For example, the former / the latter = 2: 1 to 1: 5, preferably 1.5: 1 to 1: 3, and more preferably 1: It is about 1-1: 2. When the ratio of the polyester multifilament yarn is too large, the attachment property to the pulley is lowered, and when the proportion of the polyamide multifilament yarn is too large, the belt tension maintaining property is lowered in a high load layout.

  FIG. 2 is a model diagram showing an embodiment of a twisted configuration of the core wire. FIG. 2 shows an embodiment in which two multifilament yarns of fiber 1 and fiber 2 are twisted, and at least three pieces including at least one of the yarns are bundled and twisted. Such a configuration is represented by 2 × 3, where the first number is the number of multifilament yarns in the lower twisted yarn, and the latter number is the number of lower twisted yarns.

  In the twisted yarn cord, the twist coefficient (TF) represented by the following formula (1) may be different from the twist coefficient of the upper twist and the lower twist (or medium twist) twist coefficient. From the point of property (a point at which untwisting hardly occurs), it is preferable that the twist coefficient of the upper twist and the twist coefficient of the lower twist are substantially the same.

T.A. F. = [Number of twists (times / m) × √Fineness (Tex)] / 960 (1)
The twist coefficient of the twisted yarn cord (upper twist coefficient and lower twist coefficient) is, for example, 3-7, preferably from the viewpoint that the bending fatigue resistance of the core wire can be improved and the tensile elastic modulus of the belt can be adjusted according to the load. It is about 3.5 to 6.5, more preferably about 4 to 6. In the present invention, in order to adjust the elastic modulus (belt elastic modulus) of the core wire and the bending fatigue resistance in a well-balanced manner, the upper twist coefficient is particularly 3 to 7 (particularly 4 to 6). If the upper twisting factor is too small, the bending fatigue resistance of the core wire may be reduced, and if the upper twisting factor is too large, the tensile modulus of the belt becomes excessively low and cannot be applied to a high load layout.

  The core wire may be subjected to adhesion treatment in order to improve adhesion with rubber. As the adhesion treatment, the fibers may be immersed in a resorcin-formalin-latex liquid (RFL liquid) and then dried by heating to form a uniform adhesion layer on the surface. In addition to this bonding treatment, the core fiber was dissolved in a conventional adhesive component, for example, an epoxy compound (epoxy resin or the like) or a reactive compound (adhesive compound) such as an isocyanate compound in an organic solvent. After pre-treatment by dipping in a resin-based treatment liquid and heating and drying, the treatment may be performed with an RFL solution. 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. Furthermore, if necessary, after treatment with the RFL solution, an overcoating treatment may be performed with a treatment solution in which the rubber composition is dissolved in an organic solvent (toluene, xylene, methyl ethyl ketone, etc.).

  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.

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

(Compression layer)
The compression layer can be appropriately selected according to the type of the belt. For example, a rubber composition or a polyurethane resin composition containing a rubber component and a vulcanizing agent or a crosslinking agent is used.

  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), 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.

  Examples of the polyurethane composition include a cured product (two-component curable polyurethane) of a urethane prepolymer and a curing agent.

  Among these, an unvulcanized rubber layer is formed with a rubber composition containing sulfur or an organic peroxide (especially an organic peroxide vulcanized rubber composition), and the unvulcanized rubber layer is vulcanized or crosslinked. In particular, an ethylene-α-olefin elastomer (ethylene-α-olefin rubber) is preferable because it does not contain harmful halogens, has ozone resistance, heat resistance, cold resistance, and is excellent in economy. .

  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 (total amount when combining multiple types) is, for example, 0.01 to 10 parts by mass, preferably 0.05 to 8 parts by mass, based on 100 parts by mass of rubber, 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.

  As a short fiber, the fiber similar to the fiber illustrated by the term of the said core wire can be used. 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 (PET fibers, etc.), polyamide fibers (aliphatic polyamide fibers such as polyamide 6, aramid fibers, etc.) are widely used.

  In order to improve dispersibility and adhesiveness in the rubber composition, the short fiber may be treated with a conventional adhesion treatment (or surface treatment), for example, an RFL solution.

  The average fiber length of the short fibers may be, for example, about 1 to 20 mm, preferably 2 to 15 mm, and more preferably about 3 to 10 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. 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 compressed layer is not particularly limited, and may be oriented in a random direction or may be oriented in a predetermined direction such as a belt longitudinal direction or a belt width direction.

  Although the thickness of a compression layer can be suitably selected according to the kind of belt, in the case of a V ribbed belt, it is 2-25 mm, for example, Preferably it is 2.2-16 mm, More preferably, it is about 2.5-12 mm.

(Adhesive layer)
The same rubber composition as the compression layer (rubber composition containing a rubber component such as ethylene-α-olefin elastomer) can be used for the adhesive layer. In the rubber composition of the adhesive layer, as the rubber component, the same type or the same type of rubber as the rubber component of the rubber composition of the compression 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 compression layer. The rubber composition of the adhesive layer may further contain an adhesion improver (resorcin-formaldehyde cocondensate, amino resin, etc.).

  The adhesive layer is not limited to the embodiment shown in FIG. 1. For example, in FIG. 1, the adhesive layer 6 is provided on either the compression layer 2 or the stretch layer 8, and the core wire 6 is attached to the adhesive layer 6 ) And the stretched layer 8, or between the adhesive layer 6 (stretched layer side) and the compressed layer 2. Furthermore, the adhesive layer is not an essential component, and a core wire may be embedded between the stretched layer and the compressed layer without providing the adhesive layer.

  The thickness of the adhesive layer can be appropriately selected according to the type of belt, but in the case of a V-ribbed belt, for example, 0.4 to 3.0 mm, preferably 0.6 to 2.2 mm, and more preferably 0.8 to 1. About 4 mm.

(Stretch layer)
The stretch layer may be formed of the same rubber composition as the compression layer (a rubber composition containing a rubber component such as an ethylene-α-olefin elastomer), or may be formed of a fabric (reinforcing fabric) such as a canvas. Good.

  Examples of the reinforcing cloth include cloth materials such as woven cloth, wide-angle sail cloth, knitted cloth, and non-woven cloth. Among these, a woven fabric woven in the form of plain weave, twill weave, satin weave, or a wide angle canvas or knitted fabric in which the crossing angle between the warp and the weft is about 90 to 120 ° is preferable. As the fibers constituting the reinforcing cloth, the same fibers as the short fibers can be used. The reinforcing cloth may be treated with the RFL solution (immersion treatment or the like) and then friction-coated or laminated by rubbing the rubber composition to form a rubberized canvas.

  Of these, an extension layer formed of a rubber composition is preferable. In the rubber composition of the stretch layer, a rubber of the same type or the same type as that of the rubber component of the rubber composition of the compression 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 compression layer.

  The rubber composition may further contain short fibers similar to those of the compression layer in order to suppress abnormal noise generated due to adhesion of the back rubber during back drive.

  Furthermore, an uneven pattern may be provided on the surface of the stretched layer (the back surface of the belt) in order to suppress abnormal noise during backside driving. Examples of the concavo-convex pattern include a knitted fabric pattern, a woven fabric pattern, and a suede woven fabric pattern. Of these patterns, a woven fabric pattern is preferred.

  The thickness of the stretched layer can be appropriately selected according to the type of belt, but in the case of a V-ribbed belt, for example, 0.4 to 2 mm, preferably 0.5 to 1.5 mm, more preferably 0.7 to 1.2 mm. Degree.

(Tension elastic modulus of transmission belt)
The tensile elastic modulus of the transmission belt is 20 to 35 N / (mm ·%), preferably 21 to 32 N / (mm ·%), more preferably 22 to 30 N / (mm ·%) [particularly 23 to 28 N / ( mm ·%)]. If the tensile elastic modulus of the belt is too small, the tension maintenance property in a high load layout is poor, and the belt may have an early life. On the other hand, if the belt is too large, it is difficult to attach the belt to the pulley. In addition, in this specification, in detail, the tensile elasticity modulus of a transmission belt can be measured by the method described in the Example mentioned later.

[Production method of transmission belt]
As a method for producing the transmission belt of the present invention, a conventional method can be used. For example, after a sheet for forming an extension layer and a sheet for forming an adhesive layer are wound around the circumferential surface of a cylindrical molding drum, a core wire is spiraled over the sheet for forming the adhesive layer. In order to obtain an unvulcanized (or uncrosslinked) sleeve by sequentially winding a sheet for forming an adhesive layer and a sheet for forming a compression layer, and then vulcanizing (or crosslinking) And a method for obtaining a sleeve. In this method, the core wire is embedded in the adhesive layer at a substantially central portion in the thickness direction. However, the core wire embedded in the adhesive layer is directly wound around the core wire. It may be embedded near the interface with the compressed layer.

  In this method, when a V-ribbed belt is manufactured, the rotated grinding wheel is brought into contact with the running sleeve while the obtained sleeve is hung on the driving roll and the driven roll and running under a predetermined tension. It may move so that 3-100 groove-like parts may be grind | polished at once on the surface of the compression layer of a sleeve. Further, the sleeve thus obtained is removed from the driving roll and the driven roll, the sleeve is hung on the other driving roll and the driven roll, traveled, and cut into a predetermined width by a cutter to produce a V-ribbed belt. May be.

  Furthermore, as another manufacturing method of the V-ribbed belt, the following method can also be used. That is, a sheet for forming a compression layer and a sheet for forming an adhesive rubber layer are wound in this order around a cylindrical forming drum having rib markings on the peripheral surface. Further, after spinning the core, a sheet for forming the stretched layer is wound to form an unvulcanized sleeve. Thereafter, the unvulcanized sleeve is vulcanized while being pressed against the forming drum, whereby a rib is formed on the compression layer. Ribs are formed in the obtained vulcanized sleeve, but the rib surface may be polished if necessary and cut into a predetermined width to prepare a V-ribbed belt.

  As another method of manufacturing the V-ribbed belt, a sheet for forming an extension layer and a sheet for forming an adhesive layer are wound around a flexible jacket mounted on a cylindrical forming drum, and then a sheet is formed thereon. After spinning the core wire, sheets for forming a compression layer are successively wound endlessly to form an unvulcanized sleeve. Thereafter, the flexible jacket may be expanded, and the unvulcanized sleeve may be pressed against an outer mold having an inscription corresponding to the rib portion to be vulcanized. The obtained vulcanized sleeve has a rib portion. However, if necessary, the rib surface may be polished and cut into a predetermined width to prepare a V-ribbed belt.

  Hereinafter, the present invention will be described in more detail based on examples, but the present invention is not limited to these examples. The raw materials and raw yarns used in the following examples and measuring methods or evaluation methods for each physical property are shown below. Unless otherwise specified, “part” and “%” are based on mass.

[Raw material and yarn]
Low elastic PET yarn (low PET or low elastic modulus PET): “P903B” manufactured by Teijin Fibers Ltd., average fineness 1100 dtex, multifilament yarn, single fiber fineness 5.7 dtex)
High elastic PET raw yarn (high PET or high elastic modulus PET): “P952NL” manufactured by Teijin Fibers Limited, average fineness 1100 dtex, multifilament yarn, single fiber fineness 4.4 dtex)
Polyamide 66 yarn (N66): “TYPE T-5” manufactured by Asahi Kasei Corporation, average fineness 940 dtex, single fiber fineness 6.7 dtex
EPDM polymer: “IP3640” manufactured by DuPont Dow Elastomer Japan Co., Ltd., Mooney viscosity 40 (100 ° C.)
Hydrous silica: “Nippil VN3” manufactured by Tosoh Silica Co., Ltd., specific surface area 240 m ² / g
Resorcin / formalin copolymer (resorcinol resin): Resorcinol / formalin copolymer less than 20% resorcinol / 0.1% formalin Polymeric isocyanate: Polymeric with MDI (methylenebis (1,4-phenylene) diisocyanate) as isocyanate Isocyanate (Polymeric MDI)
Carbon HAF: “Seast 3” manufactured by Tokai Carbon Co., Ltd.
Anti-aging agent: “Nonflex OD3” manufactured by Seiko Chemical Co., Ltd.
Vulcanization accelerator MBTS: 2-mercaptothiazoline, dibenzothiazyl disulfide Vulcanization accelerator CBS: N-cyclohexyl-2-benzothiazylsulfenamide Vulcanization accelerator TMTM: Tetramethylthiuram monosulfide Organic peroxide : "Parkadox 14RP" manufactured by Kayaku Akzo Corporation
Paraffin softener: “Diana Process Oil” manufactured by Idemitsu Kosan Co., Ltd.
Polyamide short fiber: “66 nylon” manufactured by Asahi Kasei Corporation

[Evaluation of raw yarn (multifilament yarn)]
(1) Tensile test As the raw yarn, a low elastic PET raw yarn, a commonly used high elastic PET raw yarn, and a polyamide 66 raw yarn were used. These raw yarns were twisted 80 times / m, and the twisted raw yarns were subjected to a tensile test in accordance with JIS L 1013 (2010), 5% elongation stress, 10% elongation stress, The strength at break (breaking strength) and elongation (breaking elongation) were measured. The tensile test was performed under the conditions of a distance between chucks of 250 mm and a tensile speed of 300 mm / min. The reason why the raw yarn is twisted is that the original yarn is composed of a plurality of filaments, so that the alignment is poor, and if a tensile test is performed in this state, the variation in measurement data increases.

(2) Dry heat shrinkage rate The raw yarn cut to 1 m length is placed in an oven set at 150 ° C. for 30 minutes, and then the raw yarn is taken out and allowed to cool naturally at room temperature for about 30 minutes. The shrinkage length (initial length 1 m—the length after heat shrinkage) was determined by measurement, and the dry heat shrinkage rate was calculated based on the following formula.

    Dry heat shrinkage (%) = (shrinkage length / initial length 1 m) × 100

[Evaluation of core wire (processing rope)]
(1) Tensile test The distance between the chucks is 250 mm, the treated rope is fixed to the chuck so as not to be loosened, and the treated rope is pulled at a tensile speed of 300 mm / min. Tensile strength (breaking strength) and elongation (breaking elongation) were measured.

(2) Bending fatigue test A specimen for a bending fatigue test was prepared by the following method. First, the following unvulcanized EPDM rubber sheet (thickness: 0.5 mm) was wound around a cylindrical mold, and the treated ropes prepared in Examples and Comparative Examples were wound on the spiral in a spiral shape. The same unvulcanized EPDM rubber sheet (thickness: 0.5 mm) was wrapped around, and the jacket was covered and heated to vulcanize (temperature 160 ° C., time 30 minutes) to prepare a vulcanized rubber sleeve. Then, two treated ropes are embedded, and the vulcanized rubber sleeve is cut with a cutter in the circumferential direction so that the treated rope is not exposed on the cut side surface, and a test piece having a width of 3 mm, a length of 50 cm, and a thickness of 1.5 mm is obtained. Produced.

  In the bending fatigue test, as shown in FIG. 3, the prepared test piece 13 is bent and wound around a pair of cylindrical rotating bars (diameter 10 mm) 12 a and 12 b arranged one above the other. Is fixed to the frame 14 and a 2 kg load 15 is applied to the other end of the test piece 13, and the pair of rotating bars 12a and 12b is reciprocated 1000 times, 5000 times, and 10,000 times in the vertical direction while maintaining a constant relative distance. (Stroke: 100 mm, cycle: 100 times / min), the winding and unwinding of the test piece 13 around the rotating bars 12a, 12b was repeated to cause bending fatigue. And using the autograph ("AGS-J10kN" manufactured by Shimadzu Corporation), the test piece 13 after bending was pulled under the condition of a tensile speed of 300 mm / min, and the strength at break of the test piece 13 was measured. . On the other hand, the strength at break of the test piece 13 before bending was measured in advance, and the strength retention was calculated based on the following formula. Higher strength retention means better flex fatigue resistance.

    Strength retention (%) = (Strength after bending / Strength before bending) × 100

(Unvulcanized EPDM sheet)
The rubber composition shown in Table 1 was kneaded with a Banbury mixer and rolled with a calender roll to produce an unvulcanized EPEM rubber sheet with a thickness of 0.5 mm.

[Evaluation of belt]
(1) Tensile test The center position of a pair of flat pulleys (diameter 75 mm) arranged vertically is previously set, and this position is set as the origin. Next, the belt manufactured in the example and the comparative example is hung on a pair of flat pulleys so that the back side of the belt is in contact with the flat pulley, and one of the flat pulleys is moved so that the belt does not loosen (approximately 0.5 N / Mm). The position of the flat pulley in this state is the initial position, the belt is pulled at a speed of 50 mm / min, and immediately after the belt stress reaches 350 N / rib (1 rib = 3.56 mm), the flat pulley is returned to the initial position. . This operation was repeated twice, and the slope (average slope) of the straight line in the region (15 to 45 N / mm) having a relatively linear relationship in the second stress-strain curve was calculated as the elastic modulus of the belt.

(2) Heat shrinkage stress A test piece for measuring heat shrinkage stress was prepared by the following method. The compressed layer and the stretch layer of the belt produced in the examples and comparative examples are sliced and removed by a slicer to obtain the remaining adhesive layer in which the core wire is embedded. Cut the unnecessary part at both ends of the test piece with a cutter so that the core wire is not exposed from the end surface, and measure the heat shrinkage stress. It was set as the test piece for doing. This test piece is fixed to the chuck so that it does not loosen at room temperature and the distance between chucks is 200 mm. After applying an initial load of 150 N, the test piece is placed in an oven set at 100 ° C. The heat shrinkage stress was obtained.

(3) Dry heat shrinkage rate The belt manufactured in the example and the comparative example is hung on a pair of grooved pulleys (diameter: 100 mm) arranged above and below so that the rib of the belt is fitted, and a load of 3 kg / rib is applied. Measure the belt length when applied. Next, this belt is put in an oven set at 120 ° C. for 60 minutes, and then the belt is taken out and naturally cooled for about 30 minutes in a room temperature atmosphere. The belt length was measured in the same manner for the cooled belt, the contraction length of the belt (belt length before contraction−belt length after contraction) was determined, and the dry heat contraction rate was calculated based on the following formula.

    Dry heat shrinkage rate (%) = (belt shrinkage length / belt length before shrinkage) × 100.

(4) Biaxial running test This running test is a test for evaluating the belt tension maintenance. As shown in FIG. 4, the test was performed using a two-axis running tester composed of a driving (Dr.) pulley having a diameter of 120 mm and a driven (Dn.) Pulley having a diameter of 120 mm. Next, the V-ribbed belt produced in each of the examples and comparative examples was hung on each pulley, and after adjusting the distance between the axes of the pulleys so that the initial tension was 70 N / rib, the rotational speed of the driving pulley was 4900 rpm, the driven A load of 3 kW was applied to the pulley, and the belt was run for 500 hours under the condition of an ambient temperature of 100 ° C. For the tension retention, the belt tension after traveling for 100 hours and the belt tension after traveling for 500 hours were measured, and the tension retention was calculated based on the following formula.

    Tensile retention rate (%) = (tension after 500 hours / tension after 100 hours) × 100.

[Examples 1-4 and Comparative Examples 1-3]
(1) Evaluation of raw yarn Table 2 shows the results of measuring the 5% elongation stress, 10% elongation stress, breaking strength, breaking elongation, and dry heat shrinkage of the yarn. A stress-strain curve is shown in FIG.

  The low-elasticity PET raw yarn was less than the high-elasticity PET raw yarn by 5% elongation stress and 10% elongation stress, and was similar to polyamide 66. Further, when the dry heat shrinkage is compared, the dry heat shrinkage increases in the order of low elastic PET yarn, polyamide 66 yarn, and high elastic PET yarn, and the dry heat shrinkage is higher than that of the conventional high elastic PET yarn. It can be seen that the shrinkage rate is low.

(2) Configuration and treatment of twisted cords Of the low-elasticity PET raw yarn, the high-elasticity PET raw yarn, and the polyamide 66 raw yarn, two types or two types of two types are twisted, and at least one of the lower twisted yarns is included 3 The book was twisted to produce a twisted cord (configuration: 2 × 3). Example 1 is a core wire in which a low-elasticity PET raw yarn and a polyamide 66 raw yarn are configured with a 1: 1 number ratio (number ratio of multifilament yarn), and an upper and lower twist coefficient is 3.0. Example 2 is the same as Example 1 except that the upper and lower twist coefficients are 6.0. Example 3 is a core wire in which a low-elasticity PET raw yarn and a polyamide 66 raw yarn are formed at a ratio of 1: 2, and the upper and lower twist coefficients are 4.0. Example 4 is a core wire in which low-elasticity PET raw yarns and polyamide 66 raw yarns are formed at a ratio of 1: 5, and the upper and lower twist coefficients are 3.0. Comparative Example 1 is a core wire in which a high-elasticity PET raw yarn and a polyamide 66 raw yarn are configured at a ratio of 1: 1, and the upper and lower twist coefficient is 3.0. Comparative Example 2 is a core wire composed of only the polyamide raw yarn 66 and having an upper and lower twist coefficient of 3.0. Comparative Example 3 is the same as Comparative Example 2 except that it is composed only of high-elasticity PET raw yarn.

  These twisted cords were heat stretched and subjected to adhesion treatment (treatment in the order of the following resin-based treatment, RFL treatment, and overcoating treatment) to produce a treated rope (core wire). The heat stretching treatment was performed in a drying furnace (temperature 230 ° C.) after the RFL treatment. Examples 1-4 were 6.0%, Comparative Example 1 was 2.0%, and Comparative Examples 2 and 3 were 2.5%. The stretching was performed at a stretching rate. Table 7 shows the results of measuring the elongation (%) at 100 N, the elongation (%) at 200 N, the strength (breaking strength) and the elongation (breaking elongation), and the strength retention at the time of cutting of the obtained twisted cord (core wire). Shown in

(Resin treatment)
The twisted cord was immersed in a pre-dip (P / D) treatment liquid (a toluene solution containing 10% by mass of polymeric isocyanate), and then heat treated at 180 ° C. for 4 minutes.

(RFL treatment)
Next, a resorcin-formalin-latex (RFL) treatment solution [resorcin and formalin prepolymer 4 parts by mass (resorcin 2.6 parts by weight, formalin 1.4 parts by mass), latex (styrene-butadiene-vinylpyridine copolymer) The mixture was immersed in a mixed solution containing 17.2 parts by mass and 78.8 parts by mass of water], and heat-treated at 230 ° C. for 2 minutes.

(Overcoating treatment)
The rubber composition (kneaded rubber) shown in Table 3 was dissolved in toluene by preparing a rolled rubber sheet through a calender roll in toluene to obtain rubber paste (ratio of 10% by mass of the rubber sheet-derived component). RFL treatment was applied to an overcoat (O / C) treatment liquid (mixture containing 50 parts by weight of rubber paste, 1 part by weight of polymeric isocyanate and 94 parts by weight of toluene) prepared by dissolving rubber paste and polymeric isocyanate in toluene. The core wire was immersed and heat-treated at 150 ° C. for 4 minutes.

(3) Belt production As a method for producing the V-ribbed belt, the following known methods were used. First, the following stretch layer sheet (EPDM unvulcanized rubber sheet) is wrapped around a cylindrical mold having a flat surface, and a treatment rope is spun into a spiral shape on the stretch layer sheet. (EPDM unvulcanized rubber sheet) and the following compression layer sheet (EPDM unvulcanized rubber sheet) were sequentially wound to prepare a molded body. After that, a vulcanization jacket is placed on the molded body and the mold is placed in a vulcanizing can. After vulcanization at a temperature of 160 ° C. for 30 minutes, the mold is removed from the molding mold and the cylindrical vulcanization is performed. A vulcanized rubber sleeve was obtained. Then, the outer surface (compressed layer) of this vulcanized rubber sleeve is polished by a grinding wheel to form a plurality of ribs, and then cut into individual belts by a cutter to obtain a V-ribbed belt (3 ribs, circumference 1100 mm). Finished. Table 7 shows the results of measurement of the elastic modulus, heat shrinkage stress, dry heat shrinkage, and tension retention of the obtained belt.

(Extension layer sheet)
The rubber composition shown in Table 4 was kneaded with a Banbury mixer and rolled with a calender roll to produce a rubber sheet with a thickness of 1.0 mm for forming an extension layer.

(Rubber sheet for forming the adhesive layer)
The rubber composition shown in Table 5 was kneaded with a Banbury mixer and rolled with a calender roll to prepare a rubber sheet with a thickness of 0.5 mm for forming an adhesive layer.

(Rubber sheet for forming the compression layer)
The rubber composition shown in Table 6 was kneaded with a Banbury mixer and rolled with a calender roll to prepare a rubber sheet with a thickness of 3.0 mm for forming a compression layer.

(Evaluation of core wire)
As is clear from the results in Table 7, Examples 1 to 4 using low elastic PET raw yarns were processed with a draw ratio as high as 6.0%, but Comparative Example 1 using high elastic PET raw yarns. It can be seen that the elongation at 100N and the elongation at 200N are high and the elastic modulus is low compared to (stretching rate 2.0%).

  When Examples 1-4 were compared, Example 2 with a high twist coefficient had the lowest elastic modulus, and conversely Example 1 with a small twist coefficient resulted in a high elastic modulus. In addition, Example 3 in which the ratio of the number of polyamide 66 raw yarns was increased and the upper and lower twist coefficients were higher than that of Example 1 was an intermediate elastic modulus between Example 1 and Example 2.

  Comparing the strength retention ratio, which is an index of bending fatigue resistance, it can be seen that Examples 1 and 2 have a higher strength retention ratio than Comparative Example 1 and are excellent in bending fatigue resistance. This indicates that the combination of the low elasticity PET yarn and the polyamide 66 yarn is better than the combination of the high elasticity PET yarn. In particular, although Comparative Example 1 has a 1: 1 ratio of the N66 yarn of Comparative Example 2 and the highly elastic PET yarn of Comparative Example 3, the tenacity retention is lower than that of Comparative Example 3. Therefore, it can be seen that the combination of the high elastic material and the low elastic material is inappropriate for the bending fatigue resistance. Although Examples 1 and 2 are inferior in bending fatigue resistance to Comparative Example 2 using only polyamide 66 yarn, it is equivalent to Comparative Example 3 using only high elastic PET yarn, which is problematic in actual use. It is a level that does not become.

(Evaluation of belt)
As is clear from the results in Table 7, the belt elastic modulus of Examples 1 to 4 was lower than that of Comparative Example 1. Moreover, when Examples 1-4 were compared, the belt elastic modulus became high in order of Example 2, Example 4, Example 3, and Example 1, and showed the tendency similar to a process rope. The belt elastic modulus was lowest in Comparative Example 2 and highest in Comparative Example 3, and this tendency was the same as that of the treated rope.

  The thermal shrinkage stress of Examples 1 to 4 was lower than that of Comparative Example 1, but higher than that of Comparative Example 2, and the tension maintenance at 100 ° C. was the same as that of Comparative Example 2 in Examples 2 and 3. Compared with that, the tension retention was high and good. In addition, Example 2 shows a tension holding rate comparable to that of Comparative Example 3, and it can be seen that there is no problem in tension maintenance. The dry heat shrinkage rates of Examples 1 to 4 were higher than those of Comparative Examples 1 to 3, but this was because the stretch rate was set high. In general, when the stretch ratio is increased, the dry heat shrinkage ratio tends to be high, but although the stretch ratios of Examples 1 to 4 are 2-3 times higher than the comparative examples, the dry heat shrinkage ratio is The value was around 2.5%. This is because the low-elasticity PET raw yarn used in the present invention has a very low dry heat shrinkage rate compared to the conventional PET raw yarn (high-elasticity PET raw yarn).

  The power transmission belt of the present invention can be used for various power transmission belts such as a friction power transmission belt and a mesh power transmission belt (toothed belt). It is useful for a friction transmission belt such as a V-belt (particularly a V-ribbed belt).

DESCRIPTION OF SYMBOLS 1 ... Core wire 2 ... Compression layer 6 ... Adhesive layer 8 ... Stretch layer 9 ... Rib part 10 ... Short fiber

Claims (5)

A power transmission belt including a belt body and a core wire extending in a belt longitudinal direction and embedded in the belt body,
The core wire is a twisted cord obtained by twisting a plurality of yarns including a strand,
The strand includes a lower twisted yarn in which a plurality of yarns including a polyester multifilament yarn including a polyester fiber and a polyamide multifilament yarn including a polyamide fiber are mixed and twisted,
Polyester multifilament yarn with a twist of 80 turns / m has a 5% stretch stress of 1.4 to 2.2 cN / dtex, and a polyamide multifilament yarn with a twist of 80 turns / m has a 5% stretch. The stress is 1.0 to 1.8 cN / dtex,
The ratio of the 5% elongation stress of the polyester multifilament yarn subjected to the 80 times / m twist and the 5% elongation stress of the polyamide multifilament yarn subjected to the 80 times / m twist is the former / the latter = 1. / 2 to 2/1,
A transmission belt having an upper twist coefficient of 3 to 7 and a tensile elastic modulus of the transmission belt of 20 to 35 N / (mm ·%). The ratio of 10% elongation stress of the polyester multifilament yarn subjected to 80 times / m twist and 10% elongation stress of the polyamide multifilament yarn subjected to 80 times / m twist is the former / the latter = 1. transmission belt of claim 1 Symbol placement is /3～1.2/1. 10% elongation stress of polyester multifilament yarn subjected to 80 times / m twist is 3.3 to 4.1 cN / dtex, and 10% elongation of polyamide multifilament yarn subjected to 80 times / m twist The transmission belt according to claim 1 or 2 , wherein the stress is 3.5 to 4.3 cN / dtex. The power transmission belt according to any one of claims 1 to 3 , wherein the polyester-based multifilament yarn has a dry heat shrinkage of 3% or less after being treated at 150 ° C for 30 minutes. The transmission belt according to any one of claims 1 to 4 , wherein the polyester multifilament yarn includes a polyalkylene arylate fiber, and the polyamide multifilament yarn includes an aliphatic polyamide fiber.

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