WO2019111639A1

WO2019111639A1 - Friction transmission belt, cord for same, and manufacturing method for same

Info

Publication number: WO2019111639A1
Application number: PCT/JP2018/041878
Authority: WO
Inventors: 田村　昌史; 武志 ▲辻▼; 拓也友田
Original assignee: 三ツ星ベルト株式会社
Priority date: 2017-12-07
Filing date: 2018-11-12
Publication date: 2019-06-13

Abstract

The present invention pertains to a friction transmission belt that includes a core cable. The core cable includes a cord comprising: a core yarn containing high elastic-modulus fibers; and a plurality of sheath yarns that are disposed around the core yarn and that contain low elastic-modulus fibers. The cord is twisted and the proportion of the average diameter of the sheath yarn to the average diameter of the core yarn is 0.2 to 0.4.

Description

Friction transmission belt, cord therefor and method for manufacturing them

The present invention relates to a friction transmission belt (for example, a V-ribbed belt) including a predetermined twist cord as a core, a twist cord suitable for such a friction transmission belt, and a method of manufacturing them.

Recently, as the fuel efficiency regulations of automobiles are intensified, vehicles equipped with an idling stop mechanism are increasing as one of the measures for improving fuel efficiency of engines. And, in restarting the engine from the idling stop state, belt-type ISG (Integrated Starter Generator) drive for driving a crankshaft from an alternator via an accessory drive belt such as a V-ribbed belt has become widespread. In belt-type ISG drive, high dynamic tension is generated in the accessory drive belt as compared with a normal engine without ISG. For example, assuming that the dynamic tension generated in the accessory drive belt without ISG installed is about 70 N / mm per 1 mm of belt width, the accessory drive belt loaded with the belt type ISG drive has a dynamic of about 100 N / mm Tension is generated. Therefore, auxiliary drive belts used in engines equipped with a belt type ISG drive are required to have high tensile elastic modulus in order to keep the belt elongation small even if high dynamic tension is applied. . Conventionally, as a core wire of V-ribbed belt used for accessory drive, a twist cord made of relatively high elastic modulus fiber such as polyester fiber or aramid fiber has been used, but the dynamic tension continues to increase. Elastic modulus is getting short. In order to cope with high dynamic tension, it is conceivable to take measures to increase the number of ribs (make the belt width wider), but if the number of ribs is increased, the pulley width also increases, so from the viewpoint of space saving and weight reduction. Is not desirable. That is, by increasing the tensile elastic modulus of the belt, a friction transmission belt such as a V-ribbed belt having high durability even with a small number of ribs is required.

In order to increase the tensile modulus of elasticity of the belt, it has been proposed to use a twisted cord made of carbon fiber having a modulus of elasticity higher than that of aramid fiber as a core wire, as disclosed in JP-A-61-129 433 (Patent Document 1). Discloses a power transmission belt using a carbon fiber twist cord as a tensile body. In this document, it is described that the twisting cord is adjusted to an upper twist coefficient of 2 to 4 and treated with resorcinol-formalin-latex (RFL), and the bending fatigue resistance is improved by using the carbon yarn twisting cord. It is described that the belt elongation during running is small and the water resistance is improved.

Japanese Patent Application Publication No. 2004-535517 (patent document 2) discloses a spiral transmission having a yarn composed of carbon fibers having a tensile elastic modulus in the range of about 50 to 350 GPa as a power transmission belt having an improved elongation resistance. A belt is disclosed comprising a cord tension member, wherein at least a portion of the carbon fiber is coated with a cord treatment composition comprising an elastomeric latex and a resorcinol-formaldehyde reaction product. Although this document exemplifies V-belts, multi-ribbed belts, and toothed power transmission belts as power transmission belts, it mainly describes toothed belts, and in the embodiment, 396 tex The toothed power transmission belt is manufactured using the carbon fiber cord of

However, while the twisted cord of carbon fiber exhibits a high elastic modulus, it has an aspect that the resistance to bending fatigue is low. That is, when the belt is repeatedly bent during use, the carbon fibers may be cut, and the strength may be easily reduced. To address such problems, WO 2004/090224 discloses a reinforcing cord comprising a carbon fiber strand and a plurality of glass fiber strands arranged around the carbon fiber strand. It is done. In this document, a carbon fiber strand of 400 tex is treated with an RFL treating solution, and a glass fiber strand of 100 tex is treated with an RFL treating solution around the obtained carbon fiber strand, and nine twisted yarns are pretwisted in the S direction. It is described that the cord is prepared by arranging the cords in the Z direction opposite to the above-mentioned ply twist direction to prepare a cord and applying a rubber-containing overcoat treatment agent to the cord to prepare a reinforcing cord . The reinforcing cord is described to have sufficient tensile strength for reinforcing a rubber product and to be able to enhance dimensional stability and resistance to bending fatigue.

Further, according to WO 2009/063952 (Patent Document 4), a rubber reinforcing cord comprising a core fiber made of high elastic modulus fiber and a plurality of strands made of glass fiber disposed around the core fiber. Is disclosed. In this cord, the upper twist direction and the lower twist direction are opposite, the number of upper twist is 1 to 3 times / 25 mm, and the ratio of the number of lower twist to the number of upper twist is in the range of 1.5 to 2.5. Is defined. In this document, a core fiber of carbon fiber and a glass fiber strand are treated with a treatment liquid (including rubber, bismaleimide and carbon black), and the glass fiber strand is twisted in the S direction by 1.7 to 4. 6 twists / 25 mm and twist 12 pieces of this twisted yarn around one core fiber of carbon fiber, and the number of twists 1.7 times / 25 mm or more in the Z direction opposite to the above-mentioned lower twist direction It is described that it was overtwisted twice / 25 mm and the treatment liquid was applied to the surface of the reinforcing cord to form a rubber layer. Such rubber reinforcing cords are described as being compatible with high bending fatigue resistance and good tensile properties.

Furthermore, Japanese Patent Laid-Open No. 2016-11736 (Patent Document 5) includes a core yarn disposed at the center, and a sheath yarn that covers the entire outer peripheral surface of the core yarn and fixes the core yarn. A toothed belt is disclosed, comprising a core wire, wherein the distance between the core wires is less than 40% of the diameter of the core wire. In this document, a carbon fiber strand is subjected to RFL treatment to be a twisted yarn, and 12 sheath yarns in which three glass fiber bundles are subjected to RFL treatment and twisted around one core yarn of this carbon fiber are disposed. It is described that a hybrid cord having a core-sheath structure was prepared by twisting, and the hybrid cord was coated with an adhesive. In this toothed belt, it is described that the bending fatigue property of the core wire is improved even in the environment where water or oil adheres, and belt narrowing is possible.

Although the reinforcing cords and belts described in Patent Documents 3 to 5 have a certain improvement in bending fatigue resistance, they may still not be sufficient under the recent severe use conditions such as belt type ISG drive. . Therefore, a friction transmission belt capable of exhibiting high durability even when high dynamic tension acts, in particular, a friction transmission belt having high power transmission and improved durability even if the belt width is small is desired. .

Japanese Patent Application Laid-Open No. 61-192,943 (claim 1, [action] [effect of the invention]) Japanese Patent Publication No. 2004-535517 (claim 1, [0001] [0005]) WO 2004/090224 (Claim 1, page 2, line 21 to line 22, embodiment) WO 2009/063952 (Claim 1, [0012], Example) Japanese Patent Application Laid-Open No. 2016-11736 (claim 1, [0013], an embodiment)

Therefore, an object of the present invention is a cord suitable for applications where high dynamic tension is generated, such as a belt type ISG drive mounted engine, a friction transmission belt (for example, a V-ribbed belt, etc.) provided with this cord and excellent in durability. And a method of manufacturing the cord and the friction transmission belt.

Another object of the present invention is to provide a cord capable of achieving high power transmissibility even if the tensile modulus is high and the belt width is small, a friction transmission belt (such as a V-ribbed belt) provided with this cord, and a method of manufacturing them. It is to do.

Still another object of the present invention is to provide a friction transmission belt (such as a V-ribbed belt) having high durability even with a small number of ribs, a cord suitable for such a friction transmission belt, and a method of manufacturing them.

As a result of intensive studies to achieve the above-mentioned problems, the present inventors have found that a core yarn (or strand) containing high modulus fibers and a plurality of sheath yarns arranged around this core yarn and including low modulus fibers In a cord (or cord) provided with (or a strand), the ratio (diameter ratio) of the average diameter of the core yarn to the average diameter of the sheath yarn, the bending fatigue resistance of the friction transmission belt, the rubber composition, It has been found that it greatly affects the adhesion of the present invention, and completed the present invention.

That is, the friction transmission belt of the present invention includes a core wire, and the core wire is disposed around a core yarn (strand) including high modulus fibers and a plurality of low modulus fibers. And a cord including a sheath yarn (strand), wherein the ratio (D2 / D1) of the average diameter D2 of the sheath yarn to the average diameter D1 of the core yarn is 0.2 to 0.4 (ie 0.2 or more and 0) .4 or less). The cord includes the core yarn and the sheath yarn disposed around the core yarn to form a twisted twist cord.

In the present invention, generally, the total fineness and the average diameter of the sheath yarn are small, and the total fineness of the sheath yarn may be, for example, about 30 to 80 tex, and the average diameter of the sheath yarn is, for example, 0.13 to 0 It may be about 25 mm. Of the core yarn and the sheath yarn, at least the sheath yarn may be a twisted (yarn-twisted) twisted yarn, and the core yarn may have no twist, and the number of twists is 1 // 10 cm or less It may be present (or may be about 0 to 1 twist per 10 cm). The cord may also be a twisted (twisted) yarn cord. The number of sheath yarns for one core yarn may be, for example, about 11 to 19. The core wire may include the core wire of the S twist cord and the core wire of the Z twist cord embedded at predetermined intervals in the rubber layer. In addition, the twisting direction of the upper twist of the core yarn and / or the sheath yarn and the upper twist of the cord may be the same. Furthermore, the high modulus fibers may comprise carbon fibers and the low modulus fibers may comprise glass fibers. An adhesive component may be attached to the surface of at least a portion of the high modulus fiber or the surface of at least a portion of the low modulus fiber. Furthermore, a rubber component may be attached to the surface of at least a part of the cord.

Furthermore, the friction transmission belt may be a belt including a compression rubber layer (for example, a V-ribbed belt), and short fibers may protrude from the surface of the compression rubber layer. The friction transmission belt (for example, a V-ribbed belt) may have a high tensile elastic modulus, for example, a tensile elastic modulus of about 240 to 500 N / (mm ·%).

Such a friction transmission belt may be mounted on a power transmission mechanism generating high dynamic tension, for example, an engine mounted with a belt type ISG drive. In such a power transmission mechanism, a dynamic tension of 85 N / mm or more may be exerted per 1 mm width of the belt.

The friction transmission belt can be manufactured by a conventional method using the core wire (or twist cord). For example, forming a rubber layer or sheet (for example, a laminate or laminated sheet including an adhesive rubber layer), which is formed of an unvulcanized rubber composition and in which the core is embedded, into a predetermined shape; The friction transmission belt can be manufactured through the steps of vulcanizing the molded body.

The invention also encompasses the cord and the method of making the same. In the cord, a plurality of the sheath yarns including the low elastic modulus fibers are disposed around the core yarn including the high elastic modulus fibers, and the cord is over-twisted, and the sheath with respect to the average diameter of the core yarns The ratio of the mean diameter of the yarn is 0.2 to 0.4. Such a cord is a sheath for an average diameter of the core yarn in a method of arranging a plurality of the sheath yarns including the low elastic modulus fiber around the core yarn containing the high elastic modulus fiber and performing an upper twist. It can be manufactured by setting the ratio of the average diameter of the yarn to 0.2 to 0.4. The core yarn and the sheath yarn may be respectively subjected to adhesion treatment, and the upper-twisted cord may be coated with a rubber composition containing a rubber component.

In the present specification, a cord embedded in a rubber layer of a belt is referred to as a "core", but the core has a form in which the core yarn is surrounded by a plurality of sheath yarns like the cord. doing. Therefore, the core wire and the code may be used synonymously. Further, the numerical value range “XX to YY” is a meaning including the numerical value “XX” and the numerical value “YY”, that is, the numerical value “XX” or more and the numerical value “YY” or less.

In the present invention, since the ratio of the average diameter of the sheath of the low modulus fiber to the average diameter of the core of the high modulus fiber is small, applications where high dynamic tension is generated such as a belt type ISG drive mounted engine (power transmission Also in the mechanism, power can be effectively transmitted with a narrow belt width, and the durability can be greatly improved. Further, since the tensile elastic modulus is also high, the durability can be improved even with a friction transmission belt having a small number of ribs (V-ribbed belt or the like).

FIG. 1 is a schematic cross-sectional view showing the form of a core wire (or twisted cord). FIG. 2 is a schematic cross-sectional view showing an example of a V-ribbed belt as a friction transmission belt. FIG. 3 is a schematic view showing a layout of a testing machine used for a bending fatigue test of the V-ribbed belt obtained in the example and the comparative example. FIG. 4 is a schematic view showing the layout of a testing machine used for the endurance running test of the V-ribbed belt obtained in the example and the comparative example.

An example of the friction transmission belt of the present invention will be described below.
[Twist cord or yarn and method for producing it]
The core wire (or twist cord) suitably used for the friction transmission belt of the present invention includes a core thread containing high modulus fiber and a sheath thread containing low modulus fiber, and has a form of a twist cord. ing. For example, as shown in FIG. 1, in the core wire (or twist cord) 1, a plurality of sheath yarns 3 are disposed around the core yarn 2, and twisted (over-twisted) to be combined, and the core The yarn 2 has a form (the core of the cord 1 is formed of the core yarn 2 and the sheath is formed of the sheath yarn 3) surrounded by a plurality of sheath yarns 3. The high modulus fiber contained in the core yarn is effective mainly to improve the resistance to tensile load, so transmission can be performed even with a narrow belt width, and belt elongation is small even if high dynamic tension occurs. It is possible to keep. The low elastic modulus fiber contained in the sheath yarn is mainly effective in improving the adhesion and reducing the shear stress, so that the interfacial peeling between the rubber composition and the cord can be suppressed, and the life of the belt can be improved.

In the present invention, in order to maximize the function of the core yarn and the sheath yarn, the ratio of the average diameter of the core yarn and the sheath yarn is important, and the average diameter of the sheath yarn is made small, The function of the core yarn and the sheath yarn can be effectively exhibited by reducing the ratio (D2 / D1) of the average diameter D2 of the sheath yarn to the average diameter D1 of the core yarn. The ratio (D2 / D1) of the average diameter D2 of the sheath yarn to the average diameter D1 of the core yarn is 0.2 to 0.4 (eg, 0.23 to 0.39). The ratio (D2 / D1) is preferably 0.25 to 0.38 (eg, 0.30 to 0.37), more preferably 0.32 to 0.37 (eg, 0.34 to 0.37). Or about 0.28 to 0.38 (eg, 0.32 to 0.36). When the core yarn and the sheath yarn are used at such a ratio (D2 / D1) of the average diameter, the bending fatigue resistance and the adhesiveness with the rubber composition can be compatible at a high level. In addition, when stress acts on the belt, shear stress is concentrated between the rubber which is easy to be deformed and the cord which is hard to be deformed, and peeling is easily generated. However, since the sheath yarn having a low elastic modulus is positioned at the outer peripheral portion of the core wire, the core wire is more easily deformed than the core yarn alone, and it is possible to alleviate the concentration of shear stress. When the ratio (D2 / D1) is less than 0.2, the adhesiveness is lowered to cause delamination easily between the core and the rubber composition, and the durability of the belt is lowered. When the ratio (D2 / D1) exceeds 0.4, bending fatigue is promoted due to an increase in bending strain, and the durability is lowered.

The average diameters D1 and D2 of the core yarn and sheath yarn are randomly selected 30 core yarns and sheath yarns in the micrograph of the cross-section of the core yarn and sheath yarn or the cross-section of the belt in the width direction. The major diameter and the minor diameter are measured to calculate the addition average diameter, and the total value of the average diameters calculated in this manner is divided by 30 to obtain an average.

(Core thread)
The high elastic modulus fiber of the core yarn may be an inorganic or organic fiber having a high tensile elastic modulus, and the tensile elastic modulus of the high elastic modulus fiber is, for example, 200 to 900 GPa (for example, 200 to 800 GPa), preferably 210 to It may be about 500 GPa (eg, 220 to 300 GPa), more preferably 220 to 270 GPa (eg, 220 to 250 GPa). The tensile modulus of elasticity of the fiber can be measured by measuring the load-elongation curve by the method described in JIS L 1013 (2010), and determining the average slope of the area under a load of 1000 MPa (the same applies hereinafter). Since the core yarn contains high modulus fibers, the tensile modulus of the belt can be improved, and power can be transmitted with a narrow belt width even in applications where high dynamic tension is generated. When the tensile modulus of elasticity of the fiber is too low, the belt elongation becomes large and the slip becomes large, which may cause poor power transmission, generation of abnormal noise, and deterioration of durability due to heat generation. On the contrary, if the tensile modulus of elasticity of the fiber is too high, the tension fluctuation of the belt becomes large, and the durability may be lowered.

As such a high elastic modulus fiber, carbon fiber, PBO (poly paraphenylene benzo bis oxazole) fiber etc. can be illustrated, for example. These fibers can be used alone or in combination of two or more. As the high modulus fiber, carbon fiber is preferable because it has a particularly high modulus. The use of carbon fiber can improve the durability with a smaller belt width even in applications where high dynamic tension is generated.

Examples of carbon fibers of the raw yarn (carbon fibers) include pitch-based carbon fibers, polyacrylonitrile (PAN) -based carbon fibers, phenol resin-based carbon fibers, cellulose-based carbon fibers, polyvinyl alcohol-based carbon fibers and the like. As a commercial item of carbon fiber, for example, Toray Industries, Inc. "Toreca (registered trademark)", Toho Tenax Corporation "Tenax (registered trademark)", Mitsubishi Chemical Corporation "Dyaleed (registered trademark)" Can be used. These carbon fibers can be used alone or in combination of two or more. Among these carbon fibers, pitch-based carbon fibers and PAN-based carbon fibers are preferable, and PAN-based carbon fibers are particularly preferable.

The carbon fiber which is a raw yarn is usually a carbon multifilament yarn containing carbon fiber. The carbon multifilament yarn may contain monofilament yarn of carbon fiber, and if necessary, monofilament yarn of fiber other than carbon fiber (for example, inorganic fiber such as glass fiber or organic fiber such as aramid fiber) May be included. The proportion of carbon fibers may be 50% by mass or more (50 to 100% by mass), preferably 80% by mass or more, and more preferably 90% by mass or more in the whole monofilament yarn (multifilament yarn). , 100% by mass, and all monofilament yarns are composed of carbon fibers. If the proportion of carbon fibers is too small, the belt elongation will be large, and if a high dynamic tension occurs, the durability may be reduced.

The multifilament yarn may contain a plurality of monofilament yarns, for example, 100 to 50,000, preferably 1,000 to 30,000, and more preferably 5,000 to 20,000 (particularly 10,000 to 15,000) of monofilament yarns. It may be The average fineness of the monofilament yarn may be, for example, about 0.1 to 5 dtex, preferably about 0.3 to 3 dtex, and more preferably about 0.5 to 1 dtex.

The total fineness of the core yarn can be selected in the range in which a desired core diameter can be obtained, for example, 100 to 1000 tex (eg, 120 to 800 tex), preferably 150 to 700 tex (eg, 200 to 600 tex), more preferably 250 It may be about 500 to 500 tex (for example, 300 to 450 tex) or about 300 to 600 tex (for example, 350 to 550 tex). By adjusting the total fineness of the core yarn to such a range, the core diameter can be controlled to an appropriate range, and the tensile modulus of elasticity of the belt can be sufficiently increased. If the total fineness is too small, the core wire diameter may become too thin and the tensile modulus and tensile strength of the belt may be reduced. If the total fineness is too large, the core diameter may become too large and the bending fatigue resistance may decrease.

The average diameter (average wire diameter) of the core yarn is, for example, 0.2 to 1 mm (for example, 0.25 to 0.95 mm), preferably 0.3 to 0.8 mm (for example, 0.35 to 0.75 mm) ), More preferably about 0.4 to 0.7 mm (for example, 0.4 to 0.65 mm), and preferably about 0.35 to 0.65 mm (for example, 0.37 to 0.63 mm). It may be. If the wire diameter of the core yarn is too small, the tensile modulus of elasticity of the belt may be reduced. If the wire diameter of the core yarn is too large, the bending fatigue resistance of the belt may be reduced.

The core yarn before doubling yarn (upper twist) may be a twisted yarn or a fiber bundle of non-twisted yarn, but the belt is preferably used even in applications where the tensile elastic modulus is increased and high dynamic tension is generated. For use, it is a fiber bundle of untwisted yarn or a twisted yarn having a twist number of 1/10 cm or less (or a twist number of 0 to 1/10 cm, or a twist number of 0 to 1 cm), preferably a untwisted yarn. The non-twisted yarn includes a substantially untwisted yarn or fiber bundle having a twist number of 0.1 times / 10 cm or less. With such a non-twisted core thread or a small number of twists, the belt elongation can be suppressed to a low level, and the belt can be suitably used in applications where high dynamic tension is generated. When the number of core yarn twists is large, the elongation of the belt becomes large, which makes it difficult to apply to applications where high dynamic tension is generated.

(Sheaf)
The low modulus fiber forming the sheath yarn is a fiber having a low tensile modulus, for example, a tensile modulus of about 50 to 150 GPa (for example, 55 to 120 GPa), preferably about 60 to 100 GPa (for example, 60 to 80 GPa) It may be fiber. By arranging the sheath yarn of the low elastic modulus fiber around the core yarn, bending fatigue resistance, adhesion to the rubber composition, shear stress relaxation effect can be enhanced, and the durability of the belt can be improved.

Examples of the low modulus fiber include glass fiber and organic fiber (aramid fiber, polyester fiber, nylon fiber, cellulose fiber, etc.). These fibers can be used alone or in combination of two or more. As the low elastic modulus fiber, glass fiber is preferable in terms of the balance of adhesion, tensile strength, elastic modulus and cost. The glass fiber has a relatively high adhesiveness to the rubber composition, and thus not only has a high effect of improving the durability of the belt but also has a relatively high elastic modulus, so that the elastic modulus of the belt can be improved.

Examples of the glass fiber of the raw yarn include alkali-free glass (E glass), high-strength glass (K, U, S glass) containing a large amount of silicon Si. Examples of commercial products of glass fiber include K glass fiber, U glass fiber (both manufactured by Nippon Sheet Glass Co., Ltd.), T glass fiber (manufactured by Nitto Boseki Co., Ltd.), R glass fiber (manufactured by Vetrotex), S glass fiber, S- 2 Glass fiber, ZENTRON glass fiber (all manufactured by Owens Corning Fiberglass) and the like. Among these glass fibers, high-strength glass (K glass fiber) is most preferable in that the tensile strength and elastic modulus of the twisted cord can be increased. The glass fiber may be surface-treated with a silane coupling agent from the viewpoint of adhesion.

The glass fiber which is a raw yarn is usually a glass multifilament yarn containing glass fiber. The glass multifilament yarn may contain monofilament yarn of glass fiber, and if necessary, monofilament yarn of fiber other than glass fiber (for example, inorganic fiber such as carbon fiber or organic fiber such as aramid fiber) May be included. The proportion of the glass fiber may be 50% by mass or more (50 to 100% by mass), preferably 80% by mass or more, more preferably 90% by mass or more in the whole monofilament yarn (multifilament yarn). , 100% by mass, and all monofilament yarns are composed of glass fibers. If the proportion of glass fiber is too small, the adhesion and shear stress relaxation effect may be reduced, and the durability of the belt may be reduced.

The sheath yarn (glass multifilament yarn, etc.) may contain a plurality of monofilament yarns. The average diameter (diameter) of the monofilaments forming the sheath yarn is not particularly limited, and is usually about 6 to 9 μm. The total fineness of the sheath yarn (glass multifilament yarn etc.) can be appropriately selected as long as the bending fatigue resistance and the adhesiveness can be compatible, and is, for example, 20 to 100 tex (for example, 25 to 90 tex), preferably 30 to 80 tex (for example, 30 to 75 tex), more preferably about 35 to 70 tex (eg, 50 to 70 tex). When the sheath yarn of such a total fineness is used, the bending fatigue resistance and the adhesiveness with the rubber composition can be compatible at a high level. If the total fineness of the sheath yarn is too small, the adhesion is lowered and delamination tends to occur between the core wire and the rubber composition, and the durability of the belt may be lowered due to the reduction of the shear stress relaxation effect. is there. If the total fineness of the sheath yarn is too large, bending fatigue is promoted by the increase of bending strain, and the durability of the belt is reduced.

The average diameter of the sheath yarn is, for example, 0.13 to 0.25 mm (eg, 0.14 to 0.24 mm), preferably 0.15 to 0.23 mm (eg, 0.15 to 0.22 mm), and further Preferably, it may be about 0.19 to 0.22 mm, or about 0.17 to 0.24 mm (eg, 0.18 to 0.23 mm). The use of a sheath yarn having such an average diameter makes it possible to achieve both bending fatigue resistance and adhesiveness with the rubber composition at a high level in the same manner as the fineness.

The sheath yarn may be a non-twisted yarn (a non-twisted fiber bundle), but in order to enhance the bending fatigue resistance and the shear stress relaxation effect, at least a sheath yarn of the core yarn and the sheath yarn is twisted. Is preferred. That is, at the time of bending, the sheath yarn located at the outer peripheral portion of the cord receives larger strain stress than the core yarn located at the central portion of the cord. Therefore, it is possible to absorb the strain stress at the time of bending and to improve the bending fatigue resistance and the shear stress relaxation effect by simultaneously twisting the sheath yarn alone in combination with the twist (upper twist) as the entire cord. The number of lower twists of the sheath yarn can be appropriately selected as long as the above effects are sufficiently exhibited, and usually 3 to 15 times / 10 cm (eg 5 to 15 times / 10 cm), preferably 5 to 12 times / 10 cm For example, it may be about 6 to 10 times / 10 cm).

(Adhesive treatment)
The core yarn (high elastic modulus fiber) and the sheath yarn (low elastic modulus fiber) are not necessarily required, but are each subjected to an adhesion treatment before twisting, and the core yarn (high elastic modulus fiber) and sheath yarn (low) It is preferable to attach (or coat) the adhesive component on the surface of at least a part (preferably almost the entire surface) of the elastic modulus fiber). The adhesive component may be attached to the surface of at least a portion of the high modulus fiber and / or the low modulus fiber, the surface of at least a portion of the core yarn and / or the sheath yarn, for example, the high modulus fiber and It may be attached to substantially the entire low modulus fiber, or substantially the entire core yarn and sheath yarn. When the adhesion process is performed, the convergence of the fibers in the core yarn and the sheath yarn is improved, and it is possible to suppress heat loss of the core wire exposed in the width cut section of the belt, and to improve the durability. In addition, when the core yarn and the sheath yarn are treated with the same adhesive, the core yarn and the sheath yarn can be integrated when the belt is vulcanized, and the shear stress relaxation effect can be enhanced.

As the adhesion treatment, a conventional method can be used, and for example, treatment (for example, immersion treatment) with a treatment solution containing resorcinol-formalin-latex (RFL) or a treatment solution containing a polyisocyanate compound and drying may be used. it can. The RFL treatment liquid may be, for example, a latex adhesive containing resorcin-formalin resin, a bismaleimide compound, a polyisocyanate compound, and the like. The rubber of the latex may be a rubber having a functional group such as a carboxyl group, such as a nitrile rubber having a carboxyl group or a hydrogenated nitrile rubber.

[Form of core wire (or twist cord or double yarn)]
The twisted cords forming the core wire have a form in which a plurality of sheath yarns are disposed around the core yarn and are twisted in an over-twisted manner. The number of sheath yarns arranged around the core yarn can be selected from the range of about 10 to 20 according to one core yarn, and it is possible to achieve both bending fatigue resistance and adhesiveness with the rubber composition at a high level In order to achieve this, it may be about 11 to 19 (for example, 12 to 19), preferably about 13 to 18 (for example, 14 to 16), and 12 to 18 (for example, 13 to 17) ) May be. If the number of sheath yarns is too small, the adhesion is lowered, delamination tends to occur between the core wire and the rubber composition, and the durability of the belt is reduced. If the number of sheath yarns is too large, the sheath yarns ride on each other to distort the shape of the core wire, or increase in bending strain promotes bending fatigue and reduces durability.

The twisted cord (or the upper twisted cord) forming the core wire is a single twist in which untwisted fiber bundles of sheath yarn are disposed around untwisted fiber bundles of the core yarn and twisted in one direction; It is also good. In addition, as a core yarn and / or a sheath yarn, a lower-twisted twisted yarn (in particular, at least a twisted yarn of a sheath yarn) is used, a sheath yarn is disposed around the core yarn, and a rung is twisted in the same direction as the lower twist direction. In addition to the first twist and the second twist, the second twist may be a middle-twisted cord. Preferred cords (twisted cords) are twisted cords that are top-twisted in the same direction as or opposite to the first twist direction, in particular, those that are top-twisted in the same direction as the first twist direction. The bending fatigue resistance is improved in the twisted cord in which the upper twisting direction and the lower twisting direction are opposite to each other in the same direction as the lower twisting direction, as compared with the twisted cord in which the upper twisting direction and the lower twisting direction are opposite.

The number of upper twists of the core wire (or the upper twist cord) can be selected, for example, in the range of about 3 to 15 times / 10 cm, usually 5 to 15 times / 10 cm (eg 5 to 14 times / 10 cm), more preferably May be about 6 to 12 times / 10 cm (eg, 6 to 10 times / 10 cm). Such a twisted number of core wires (or twisted cords) can reduce the elongation while maintaining the bending fatigue resistance. When the number of twists of the core wire (or twist cord) is increased, the relaxation effect to shear stress can be enhanced, and the bending fatigue resistance can be improved. If the number of twists of the core wire (or twist cord) is too small, the resistance to bending fatigue may decrease to reduce the durability of the belt, and if the number of twists of the core wire (or twist cord) is too large, the resistance Although it is excellent in bending fatigue resistance, there is a possibility that the tensile modulus of elasticity and the tensile strength decrease and the elongation also increases.

The average diameter (average wire diameter or core wire diameter) of the core wire (or upper twist cord) is, for example, 0.3 to 1.5 mm (eg, 0.4 to 1.4 mm), preferably 0.5 to 1 .3 mm (e.g., 0.6 to 1.2 mm), and more preferably 0.7 to 1.2 mm (e.g., 0.75 to 1.2 mm), or 0.65 to 1.25 mm (e.g. For example, it may be about 0.75 to 1.15 mm). If the core wire diameter (or twisted cord diameter) is too small, the tensile modulus of elasticity of the belt may be decreased. If the core wire diameter (or twisted cord diameter) is too large, the bending fatigue resistance of the belt may be reduced. There is.

(Coating process)
As described above, since the adhesion between the fibers, between the core yarn and the sheath yarn, and between the core and the rubber can be improved by the adhesion treatment of the core yarn and / or the sheath yarn, the cord (twisted cord) is not necessarily required. Although it is not necessary to perform adhesion processing, a rubber component (for example, a rubber of an adhesive rubber layer to be described later) is formed on the surface of at least a part (preferably substantially the whole) of the twisted cord It is preferred to apply (or coat) the components). The adhesion (or coating) of the rubber component is carried out by coating (or overcoating) the cord with a rubber composition containing the rubber component (for example, a rubber paste in which the rubber component is dissolved in a solvent such as toluene). It can do by doing. For example, after immersing the twisted cord in a rubber-containing composition (rubber paste), it may be dried, heat-treated, and coated. The twist cord subjected to such a coating treatment can further improve the adhesion to rubber compared to a core wire obtained by subjecting the core yarn and / or the sheath yarn to only the adhesion treatment, and it is possible to the shear stress. The relaxation effect can be enhanced and the durability of the belt can be improved.

Friction transmission belt
In the present invention, high tensile modulus and resistance to bending fatigue and durability can be realized, so friction transmission belts such as flat belts, V-belts (wrapped V-belts, low-edge V-belts, low-edge cogged V-belts, V-ribbed belts) Etc. (especially, V-ribbed belt etc.). V-ribbed belts are preferred, especially in applications where high dynamic tension is generated. Although Patent Document 2 exemplifies a V-belt, a multi-ribbed belt, and a toothed power transmission belt as a power transmission belt, no specific study is made on the V-ribbed belt. In addition, the toothed power transmission belt that is specifically studied is significantly different from the V-ribbed belt in the power transmission mechanism. Therefore, the toothed belt and the friction transmission belt (such as the V-ribbed belt) have different applications, problems, and required strength levels, and the configuration of the toothed belt is not very useful in the friction transmission belt.

A friction transmission belt such as a V-ribbed belt may include the core (or twisted cord), and a plurality of the cords are usually embedded in a rubber layer (for example, an adhesive rubber layer) of the friction transmission belt. The plurality of cords respectively extend in the longitudinal direction of the belt and are spaced apart from each other at a predetermined pitch in the widthwise direction of the belt.

(Core pitch)
The core pitch (the distance between the centers of two cords adjacent to each other in the belt) is preferably smaller because it can increase the tensile strength and tensile modulus of the belt. However, if the core wire pitch is too small, adjacent core wires may partially overlap (run up), or rubber may not easily flow between the core wires, which may reduce adhesion. In addition, there is a possibility that the bending fatigue resistance may be reduced by contact and rubbing between the core wires as the belt bends. Therefore, it is desirable that the core pitch be slightly larger than the core diameter.

The core pitch can be selected from a range larger than the core diameter by about 0.01 to 1 mm, and the core pitch is 0.05 to 0.8 mm (for example, 0.1 to 0.5 mm) than the core diameter. And more preferably 0.2 to 0.4 mm (especially 0.2 to 0.3 mm). Specifically, the core pitch is, for example, 0.5 to 2 mm (for example, 0.6 to 1.8 mm), preferably 0.7 to 1.7 mm (for example, 0.8 to 1.6 mm), More preferably, it may be about 0.8 to 1.5 mm (eg, 0.9 to 1.4 mm), and particularly about 0.85 to 1.5 mm (eg, 0.9 to 1.35 mm). If the core pitch is too small, the cords may rub against each other as the belt bends to reduce the belt strength, or problems such as running on the core may occur at the time of manufacture. If the core pitch is too large, Even if fibers with high tensile modulus (such as carbon fibers) are used, the tensile modulus of the belt may be low.

In addition, as for the plurality of cords, cords of cords twisted in the same direction (for example, S-twist cords twisted in the S direction, Z-twist cords twisted in the Z direction) are separated by a predetermined distance (or The core wire of the S twist cord and the core wire of the Z twist cord may be combined and buried. For example, the core of the S-strand cord and the core of the Z-strand cord may be embedded regularly (for example, at equal intervals) or irregularly at predetermined intervals, usually regularly For example, they may be buried alternately. The straightness of the belt can be enhanced by embedding the core wire of the S twist cord and the core wire of the Z twist cord. That is, when only the core wire of the S twist cord or only the core wire of the Z twist cord is embedded as a core wire, the untwisting torque of the core wire causes the belt to be strongly biased to the left or right with respect to the traveling direction. When the vehicle travels in an offset direction, the wear of the friction transmission surface and the belt end surface is promoted, and the durability decreases. On the other hand, when the core of the S twist cord and the core of the Z twist cord are embedded (in particular, alternately arranged and embedded), the untwisting torque of the core is offset and the straightness of the belt is enhanced, Durability can be improved.

The details of the friction transmission belt will be described below, taking the V-ribbed belt as an example.

[V-ribbed belt]
The form of the V-ribbed belt is not particularly limited as long as it has a plurality of V-ribs extending in parallel to each other along the longitudinal direction of the belt, and for example, the form shown in FIG. 2 is exemplified. FIG. 2 is a schematic cross-sectional view showing an example of the V-ribbed belt of the present invention. The V-ribbed belt shown in FIG. 2 is an adhesive rubber layer in which a compression rubber layer 12 and a core (or twisted cord) 1 are embedded in the longitudinal direction of the belt sequentially from the lower surface (inner peripheral surface) to the upper surface (rear surface) of the belt. 14 has a form in which a stretch layer 15 composed of a cover canvas (woven fabric, knitted fabric, non-woven fabric, etc.) or a rubber composition is laminated. A plurality of V-shaped grooves extending in the longitudinal direction of the belt are formed in the compression rubber layer 12, and a plurality of V-rib portions 13 (in FIG. 2) shown in FIG. In this case, four of them are formed, and the two inclined surfaces (surfaces) of the V-rib portion 13 form a friction transmission surface and transmit power (friction transmission) in contact with the pulley. In the adhesive rubber layer 14, a plurality of core wires (or twisted cords) 1 respectively extend in the longitudinal direction of the belt and are spaced apart from each other at a predetermined pitch in the width direction of the belt.

The form of the V-ribbed belt is not limited to the form shown in FIG. 2, and it is sufficient if at least a portion has a compressed rubber layer having a transmission surface capable of contacting the V-rib groove (V groove) of the pulley. , A tension layer, a compression rubber layer, and a core wire (or a twist cord) embedded along the longitudinal direction of the belt. In the V-ribbed belt of the present invention, for example, the core wire (or twisted cord) 1 may be embedded between the stretch layer 15 and the compressed rubber layer 12 without providing the adhesive rubber layer 14. Furthermore, the adhesive rubber layer 14 is provided on either the compression rubber layer 12 or the stretch layer 15, and the core wire (or twist cord) 1 is provided between the adhesive rubber layer 14 (the compression rubber layer 12 side) and the stretch layer 15, Alternatively, it may be embedded between the adhesive rubber layer 14 (stretching layer 15 side) and the compressed rubber layer 12.

In addition, at least the compressed rubber layer 12 may be formed of the rubber composition described in detail below, and the adhesive rubber layer 14 may be formed of a conventional rubber composition used as an adhesive rubber layer. Preferably, the stretch layer 15 may be formed of a conventional cover canvas or rubber composition used as a stretch layer, and may not be formed of the same rubber composition as the compressed rubber layer 12.

In the V-ribbed belt, the number of V-ribs (the number of ribs) is four in FIG. 2 and can be selected from the range of about 2 to 6. However, in the present invention, the durability of the belt can be improved even if the number of ribs is small. It is a major feature that it can be improved, and the number of ribs is three to five, preferably four. In the present invention, by setting the number of ribs as small as about 3 to 5, it is possible to meet the demand for space saving and weight reduction. If the number of ribs is too small, even if carbon fibers are used, the tensile elastic modulus and tensile strength may be insufficient. If too large, the requirements for space saving and weight reduction may not be sufficiently satisfied.

V-ribbed belts are suitable for applications where high dynamic tension is generated, for example, in engines equipped with belt type ISG drive, high dynamic tension acts on the belt at engine start, and such start is frequent Repeated. Therefore, the V-ribbed belt is required to have higher tensile strength than a normal belt. In such applications, the tensile strength of the V-ribbed belt may be 420 N / mm or more (eg, 420 to 1000 N / mm), preferably 560 N / mm or more, and more preferably 620 N, as a value per 1 mm of belt width. / Mm or more (especially 680 N / mm or more), preferably 750 to 1000 N / mm (especially 800 to 900 N / mm), especially for applications with high dynamic tension generation. When the tensile strength of the belt is adjusted to such a range, even if a high dynamic tension acts on the belt, it shows sufficient durability without cutting.

The friction transmission belt of the present invention (in particular, V-ribbed belt) has a high tensile elastic modulus, and the tensile elastic modulus is, for example, 240 to 500 N / (mm ·%) (for example, 270 to 490 N / (mm ···). %), Preferably 300 to 480 N / (mm ·%) (eg, 350 to 480 N / (mm ·%)), more preferably 400 to 470 N / (mm ·%) (eg, 420 to 450 N / (mm)・%) May be about. When the tensile elastic modulus of the belt is small, the belt elongation becomes large and the slip becomes large, and there is a possibility that the power transmission failure, the generation of abnormal noise, and the deterioration of durability due to heat generation may occur. When the tensile modulus of elasticity of the belt is too large, the tension fluctuation of the belt becomes large, and the durability may be reduced.

In the present specification and claims, the tensile strength and the tensile elastic modulus of the V-ribbed belt can be measured by the methods described in the examples described later.

As an engine equipped with a belt type ISG drive to which a friction transmission belt (especially V-ribbed belt) is suitably applied (mounted), for example, 85 N / mm or more (for example, about 90 to 120 N / mm) per 1 mm width of belt It may be an engine on which dynamic tension acts. Even under such severe conditions, the effects of the friction transmission belt (particularly, V-ribbed belt) of the present invention are more effectively exhibited. The engine equipped with the belt type ISG drive may be an engine equipped with the belt type ISG drive provided with a tensioner on the back of the belt.

In particular, the friction transmission belt of the present invention has high durability and excellent power transmission even if the width of the belt is small. Therefore, the width of the belt is not particularly limited, and may be, for example, about 0.5 to 5 cm (for example, 0.7 to 4 cm), preferably about 0.8 to 3 cm (for example, 1 to 2 cm).

(Rubber composition)
The compression rubber layer 12, the adhesive rubber layer 14 and the stretch layer 15 can be formed of a rubber composition containing a rubber component. In particular, by forming the compression rubber layer 12 with a rubber composition, excellent quietness and power transmission performance can be imparted, and by forming the compression rubber layer 12 and the adhesive rubber layer 14 with a rubber composition, existing components can be obtained. Using the method, it is possible to carry out an adhesion process with the core wire (or twist cord) 1.

The rubber component may be a vulcanizable or crosslinkable rubber, for example, diene rubber (natural rubber, isoprene rubber, butadiene rubber, chloroprene rubber, styrene butadiene rubber (SBR), acrylonitrile butadiene rubber (nitrile rubber), hydrogenated nitrile rubber Etc., ethylene-α-olefin elastomer, chlorosulfonated polyethylene rubber, alkylated chlorosulfonated polyethylene rubber, epichlorohydrin rubber, acrylic rubber, silicone rubber, urethane rubber, fluororubber and the like. These rubber components can be used alone or in combination of two or more. Preferred rubber components are ethylene-α-olefin elastomers (ethylene-propylene copolymer (EPM), ethylene-propylene-diene terpolymer (EPDM), etc.) and chloroprene rubber. Furthermore, ethylene-α-olefin elastomer (ethylene-propylene copolymer (EPM), which does not contain harmful halogen, has ozone resistance, heat resistance, cold resistance, weather resistance, and can reduce the weight of the belt. Particularly preferred are ethylene-propylene-diene terpolymers (EPDM) and the like. In a composition in which the rubber component contains an ethylene-α-olefin elastomer, the proportion of the ethylene-α-olefin elastomer in the rubber component may be 50% by mass or more (particularly about 80 to 100% by mass), 100% by mass (Ethylene-α-olefin elastomer only) is preferred.

The rubber composition may further contain short fibers. Examples of short fibers include polyolefin fibers (polyethylene fibers, polypropylene fibers, etc.), polyamide fibers (polyamide 6 fibers, polyamide 66 fibers, polyamide 46 fibers, aramid fibers, etc.), polyalkylene arylate fibers (eg, polyethylene terephthalate (eg, polyethylene terephthalate) PET) fiber, polytrimethylene terephthalate (PTT) fiber, polybutylene terephthalate (PBT) fiber, C _2-4 alkylene C _8-14 arylate fiber such as polyethylene naphthalate (PEN) fiber), vinylon fiber, polyvinyl alcohol Synthetic fibers such as fibers and polyparaphenylene benzobisoxazole (PBO) fibers; natural fibers such as cotton, hemp and wool; and inorganic fibers such as carbon fibers. These short fibers can be used alone or in combination of two or more. In order to improve the dispersibility and adhesion in the rubber composition, the short fibers may be subjected to a conventional adhesion treatment (or surface treatment) in the same manner as the core yarn, the sheath yarn and the cord.

In particular, the friction transmission belt (particularly, V-ribbed belt) of the present invention can suppress wear of rubber and improve durability even under high dynamic tension when applied to applications where high dynamic tension is generated. Therefore, the compressed rubber layer and the stretch layer preferably contain short fibers, and it is particularly preferable that the short fibers protrude from the surfaces of the compressed rubber layer and the stretch layer (in particular, the compressed rubber layer). As a method of causing the short fibers to protrude from the surface of the compression rubber layer, a method of embedding the short fibers in the compression rubber layer in a state where the short fibers protrude from the surface of the compression rubber layer, flocking the short fibers on the surface of the compression rubber layer And the like. In a friction transmission belt (particularly, a V-ribbed belt) including a compression rubber layer in which short fibers protrude from the surface and a stretch layer (particularly, a compression rubber layer), the wear resistance of the compression rubber layer can be enhanced, and bending fatigue or peeling is caused. It is possible to prevent the compression rubber layer from being worn out and its durability being reduced before breakage occurs.

The rubber composition may further contain conventional additives. Commonly used additives include, for example, a vulcanizing agent or a crosslinking agent (or a crosslinking agent system) (such as a sulfur-based vulcanizing agent), a co-crosslinking agent (such as bismaleimides), a vulcanization aid or a vulcanization accelerator ( Thiuram accelerators etc.), vulcanization retarders, metal oxides (zinc oxide, magnesium oxide, calcium oxide, barium oxide, iron oxide, copper oxide, copper oxide, aluminum oxide etc.), enhancers (eg carbon black and so on) , Silicon oxides such as hydrous silica, fillers (clay, calcium carbonate, talc, mica etc.), softeners (eg paraffin oils, oils such as naphthenic oils etc), processing agents or processing aids (stearin Acids, metal stearates, waxes, paraffins, fatty acid amides, etc., anti-aging agents (antioxidants, thermal anti-aging agents, flex crack inhibitors, anti-ozonants, etc.), colorants, tackifiers , Plasticizers, coupling agents (silane coupling agent, etc.), stabilizers (UV absorbers, heat stabilizers, etc.), flame retardants, antistatic agents and the like. These additives may be used alone or in combination of two or more. The metal oxide may act as a crosslinking agent. In addition, the rubber composition forming the adhesive rubber layer 14 in particular may contain an adhesion improver (resorcin-formaldehyde cocondensate, amino resin, etc.).

The rubber compositions forming the compression rubber layer 12, the adhesive rubber layer 14 and the stretch layer 15 may be identical to one another or may be different from one another. Similarly, the short fibers contained in the compression rubber layer 12, the adhesive rubber layer 14 and the stretch layer 15 may be identical to one another or may be different from one another.

(Cover canvas)
The stretch layer 15 may be formed of a cover canvas. The cover canvas can be formed of, for example, a woven fabric, a wide angle canvas, a knitted fabric, a cloth material (preferably a woven fabric) such as a non-woven fabric and the like, and if necessary, an adhesion treatment, for example, treatment with an RFL solution (immersion treatment, etc. ) Or rubbing the adhesive rubber into the cloth material, or laminating (coating) the adhesive rubber and the cloth material, and then laminating on the compressed rubber layer and / or the adhesive rubber layer in the form described above. Good.

The stretch layer 15 may also be a stretch layer coated on the surface of the rubber layer with a cloth (such as the above-mentioned cover canvas). Such a stretch layer is preferably applied to an engine equipped with a belt type ISG drive with a tensioner on the back of the belt. As a stretch layer applied to an engine equipped with a belt type ISG drive with a tensioner, in addition to a stretch layer coated on the surface with a fabric, a stretch layer containing short fibers, a surface coated with a fabric and a stretch containing short fibers Layers are also preferred. By applying these stretch layers, the durability can be improved even in a belt type ISG drive with tensioner, which is also required to have wear resistance to the stretch rubber layer.

[Method of manufacturing friction transmission belt]
A known or conventional method can be used to manufacture the friction drive belt of the present invention, and the core layer (or twist cord) may be embedded in the rubber layer instead of the conventional core line. That is, a step of forming a rubber layer or sheet (for example, a laminate or laminated sheet including an adhesive rubber layer), which is formed of an unvulcanized rubber composition and in which the core (or twist cord) is embedded, into a predetermined shape By passing through the process of vulcanizing the molded product and the molded product, the friction transmission belt can be manufactured, and after the vulcanization process, the vulcanized molded product is processed in the processing process (processing processes such as cutting and rib processing) You may process it. For example, the core wire (or twist cord) is embedded in the rubber layer, molded into a tubular shape with a mold, and vulcanized to form a sleeve, and the sleeve is cut to a predetermined width to form a friction transmission belt May be manufactured. For example, among the friction transmission belts, the V-ribbed belt has, for example, an unvulcanized rubber composition for each of the compression rubber layer 12, the adhesive rubber layer 14 in which the core wire (or twist cord) 1 is embedded, and the stretching layer 15. The laminate can be formed into a cylinder, and the laminate can be formed into a cylindrical shape by a molding die, and vulcanized to form a sleeve, and the vulcanized sleeve can be cut to a predetermined width. More specifically, the V-ribbed belt can be manufactured by the following method.

(First manufacturing method)
First, the stretch layer sheet is wound around a cylindrical molding mold (mold or mold) having a smooth surface, and a core (or twisted cord) forming a core is spirally spun on this sheet, Further, a sheet for adhesive rubber layer and a sheet for compressed rubber layer are sequentially wound to prepare a molded body. Thereafter, the molding mold is accommodated in a vulcanizing can in a state where the molding jacket is covered from above the molding, and after vulcanization under predetermined vulcanization conditions, the molding is removed from the molding mold and cylindrical vulcanization is carried out. Get a rubber sleeve. Then, the outer surface (compressed rubber layer) of the vulcanized rubber sleeve is polished by a grinding wheel to form a plurality of ribs, and then the vulcanized rubber sleeve is cut in the longitudinal direction of the belt by a predetermined width using a cutter. Finish to V-ribbed belt. In addition, the V-ribbed belt provided with the compression rubber layer which has a rib part in an internal peripheral surface is obtained by reversing the cut belt.

(Second manufacturing method)
First, using a cylindrical inner mold having a flexible jacket attached to the outer peripheral surface as the inner mold, the stretch layer sheet is wound around the flexible jacket on the outer peripheral surface, and a core wire is formed on this sheet (core Alternatively, the twist cords) are helically spun, and the compressed rubber layer sheet is wound to produce a laminate. Next, as an outer mold that can be attached to the inner mold, a cylindrical outer mold in which a plurality of rib molds are engraved on the inner circumferential surface is used, and the inner mold in which the laminate is wound is housed in the outer mold. , Installed concentrically. Thereafter, the flexible jacket is expanded toward the inner peripheral surface (rib type) of the outer mold, and the laminate (compressed rubber layer) is pressed into the rib type and vulcanized. Then, after removing the inner mold from the outer mold and removing the vulcanized rubber sleeve having a plurality of ribs from the outer mold, the vulcanized rubber sleeve is cut by a predetermined width in the longitudinal direction of the belt using a cutter. Finished with a ribbed belt. In this second manufacturing method, the laminate provided with the stretch layer, the core and the compressed rubber layer can be expanded at one time to obtain a sleeve (or V-ribbed belt) having a plurality of ribs.

(Third manufacturing method)
In relation to the second manufacturing method, for example, the method disclosed in Japanese Patent Application Laid-Open No. 2004-82702 (in which only the compressed rubber layer is expanded into a preformed body (semi-vulcanized state), and then a stretching layer A method may be employed in which the core body is expanded, pressure-bonded to the preform, and vulcanization integration is performed to complete the V-ribbed belt).

The present invention will be described in more detail based on examples given below, but the present invention is not limited by these examples.

[Raw materials / blending]
(Core yarn composition raw yarn)
Carbon fiber 1: Toray Industries, Inc. "TORAYCA (registered trademark) T400HB", tensile modulus of elasticity 230 GPa, single yarn fineness 0.67 dtex, number of filaments 6000, total fineness 400 tex
Carbon fiber 2: Toray Industries, Inc. "TORAYCA (registered trademark) T700SC", tensile elastic modulus 230 GPa, single yarn fineness 0.67 dtex, filament number 12000, total fineness 800 tex
Carbon fiber 3: Toray Industries, Inc. "TORAYCA (registered trademark) T400HB", tensile elastic modulus 230 GPa, single yarn fineness 0.67 dtex, number of filaments 3000, total fineness 200 tex
(Sheath yarn composition yarn)
Glass fiber: "Micro Glass (registered trademark) high strength glass" manufactured by Nippon Sheet Glass Co., Ltd.

(Adhesive treatment solution)
Carboxyl-modified hydrogenated nitrile rubber latex as a main component, in solid content, contains 25 parts by mass of 4,4'-bismaleimidodiphenylmethane / 100 parts by mass (phr), 25 parts by mass of blocked polyisocyanate / 100 parts by mass (phr) Aqueous mixture. Total solid concentration 20% by mass. In addition, "phr" shows the mass part of the additive with respect to 100 mass parts of rubber | gum in conversion of solid content.

(Overcoat treatment solution)
A diluted solution of Tolue's adhesive “Kemlock 233X” in toluene, solid concentration 10% by mass.

(Belt component material)
EPDM: Dow DuPont “NORDEL® IP 3640”, Mooney viscosity 40 (100 ° C.)
Carbon black HAF: "Siest (registered trademark) 3" manufactured by Tokai Carbon Co., Ltd.
Hydrous silica: "Nipsil (registered trademark) VN 3" manufactured by Tosoh Silica Corporation, BET specific surface area 240 m ² / g
Resorcinol formaldehyde condensate: "Phenacolite Resin (B-18-S) (less than 20% by mass of resorcinol, less than 0.1% by mass of formalin) manufactured by INDSPEC Chemical Corporation"
Anti-aging agent: SEIKO CHEMICAL Co., Ltd. "non-flex (registered trademark) OD3"
Vulcanization accelerator DM: di-2-benzothiazolyl disulfide polyamide short fiber: "66 nylon" manufactured by Asahi Kasei Co., Ltd.
Paraffin-based softener: "Diana (registered trademark) process oil" manufactured by Idemitsu Kosan Co., Ltd.
Organic peroxide: Kayaku Akzo Co., Ltd. "Percadox (registered trademark) 14RP"
Cotton canvas with rubber: A treated canvas in which the adhesive rubber of Table 1 is rubbed into a canvas (weight 80 g / m ² ) in which a 20th cotton thread is plain-woven at a thread density of 75/50 mm.

[Preparation of core wire]
Example 1
First, a carbon fiber 1 having a total fineness of 400 tex was immersed in the adhesion treatment solution for 10 seconds and then dried at 150 ° C. for 2 minutes to produce a core yarn.

In addition, after immersing a glass fiber with a total fineness of 33 tex in the adhesion treatment solution for 10 seconds, it is dried at 150 ° C. for 1 minute, and further twisted 8 times / 10 cm in the S direction to produce a sheath yarn (bottom twist) did. Sixteen sheath yarns were disposed around the adhesively treated core yarn, and twisted in the S direction at 8 twists / 10 cm (upper twist) to produce an S-twist cord having a core-sheath structure. On the other hand, Z twist cords were also produced in the same manner as described above except that the twist direction of the first twist and the upper twist was set to the Z direction.

After immersing the obtained S twist and Z twist twist cords in the overcoat treatment solution for 5 seconds, respectively, they are dried at 100 ° C. for 3 minutes, and treated cords (treated S twist cord and treated Z twist cord) ( A diameter of 0.99 mm) was produced.

Example 2
Treated cords (treated S twist cord and treated Z twist cord) (diameter 1.) in the same manner as in Example 1 except that the total fineness of the glass fibers constituting the sheath yarn is 66 tex and the number of sheath yarns is 12. 10 mm).

Example 3
A treated cord (treated S twist cord and treated in the same manner as in Example 1 except that the carbon fibers constituting the core yarn are changed to carbon fiber 3 (total fineness 200 tex) and the number of sheath yarns is set to 12 Z twist cord) (diameter 0.78 mm) was obtained.

Comparative Example 1
First, a carbon fiber 1 having a total fineness of 400 tex was immersed in the adhesion treatment solution for 10 seconds, dried at 150 ° C. for 2 minutes, and twisted for 8 times / 10 cm in the S direction to produce a single twist cord.

On the other hand, a Z twist single twist cord was also produced in the same manner as above except that the twist direction was set to the Z direction.

The obtained S twist and Z twist single twist cords were each immersed in the overcoat treatment solution for 5 seconds and then dried at 100 ° C. for 3 minutes to prepare treated cords (diameter 0.71 mm).

Comparative example 2
A treated cord (diameter 1.00 mm) was obtained in the same manner as in Comparative Example 1 except that the carbon fiber 1 was changed to a carbon fiber 2 (total fineness 800 tex).

Comparative example 3
Treated cords (treated S twist cord and treated Z twist cord) (diameter: 0.) in the same manner as in Example 1 except that the total fineness of the glass fibers constituting the sheath yarn is 22 tex and the number of sheath yarns is 20. 95 mm).

Comparative example 4
Treated cords (treated S twist cord and treated Z twist cord) (diameter 1.) in the same manner as in Example 1 except that the total fineness of the glass fibers constituting the sheath yarn is 99 tex and the number of sheath yarns is ten. 18 mm).

[Production of belt]
First, one-ply (one-ply) rubber-covered cotton canvas is wound around the outer periphery of a cylindrical molding mold having a smooth surface, and the non-added rubber composition shown in Table 1 is formed on the outside of this cotton canvas. A sheet for bonding rubber layer of sulfur was wound. Next, on the adhesive rubber layer sheet, the two treated cords (S twist cords, with the treated cords of S twist and the treated cords of Z twist arranged in parallel at a predetermined pitch shown in Table 3 Z-twisted cord) is helically spun and wound, and further, an unvulcanized adhesive rubber layer sheet formed of the above rubber composition and an unvulcanized formed of the rubber composition shown in Table 2 The sheet for the compression rubber layer was wound in order. The molding mold was placed in a vulcanizer and vulcanized in a state where the vulcanizing jacket was disposed outside the compression rubber layer sheet. The cylindrical vulcanized rubber sleeve obtained by vulcanization is removed from the molding mold, and the compressed rubber layer of the vulcanized rubber sleeve is ground by a grinder to simultaneously form a plurality of V-shaped grooves, and then cylindrical vulcanized. The V-ribbed belt (circumferential length 1100 mm) in which three ribs were formed was obtained by circumferentially cutting the rubber sleeve with a cutter and rounding it. In the obtained belt, in the cross-sectional view in the direction shown in FIG. 2, the treated cord of S twist as a core and the treated cord of Z twist were alternately arranged in parallel.

[Bending fatigue test]
The test was performed using a testing machine in which a drive pulley (Dr.) with a diameter of 120 mm, a tension pulley (Ten.) With a diameter of 45 mm, a driven pulley (Dn.) With a diameter of 120 mm, and an idler pulley (IDL.) With a diameter of 85 mm were arranged in order. (Figure 3 shows the layout of the tester). A V-ribbed belt is hung around each pulley of the tester, the number of revolutions of the drive pulley is 4900 rpm, the winding angle of the belt on the idler pulley is 120 °, the winding angle of the belt on the tension pulley is 90 °, and the load of the driven pulley A constant load (559 N) was applied at 8.8 kW, and the belt was run for 200 hours at an ambient temperature of 120 ° C. The tensile strength of the belt before and after traveling was measured, and the value converted to the tensile strength per rib and the strength retention are shown in Table 3. It can be determined that the higher the strength retention, the higher the bending fatigue resistance.

High load endurance test [durability running test (running life)]
The test was performed using a testing machine in which a drive pulley (Dr.) with a diameter of 120 mm, a tension pulley (Ten.) With a diameter of 45 mm, a driven pulley (Dn.) With a diameter of 120 mm, and an idler pulley (IDL.) With a diameter of 80 mm were arranged in order. (Figure 4 shows the layout of the tester). A V-ribbed belt is hung around each pulley of the tester, the number of revolutions of the drive pulley is 4900 rpm, the winding angle of the belt on the idler pulley is 120 °, the winding angle of the belt on the tension pulley is 90 °, and the load of the driven pulley A constant load (810 N) was applied at 8.8 kW, and the belt was allowed to travel with an ambient temperature of 120 ° C. and an upper limit of 300 hours. The belt after running is observed visually and with a microscope to check if any defects such as peeling or pop-out occur. If no defects occur, durability is regarded as no problem, and if defects are confirmed, the defects are evaluated. It recorded in Table 3.

[Tensile strength]
The obtained V-ribbed belt is pulled at a tensile speed of 50 mm / min using a universal testing machine (“UH-200 kNX” manufactured by Shimadzu Corporation), and the strength (tensile strength) at break of the V-ribbed belt is measured. did. The strength (tensile strength) at break of the V-ribbed belt was also measured after the bending fatigue test to calculate the strength retention rate.

[Tensile modulus]
Attach a pair of flat pulleys (75 mm in diameter) to the lower fixed part and the upper load cell connection part of Autograph ("AGS-J10kN" manufactured by Shimadzu Corp.) so that the back side of the V-ribbed belt contacts the flat pulley The ribbed belt was hung on a flat pulley. Next, the upper flat pulley was raised to apply stress (about 14 N / mm) to the extent that the V-ribbed belt did not loosen. With the position of the upper flat pulley in this state as the initial position, raise the upper flat pulley at a speed of 50 mm / min, and immediately lower the upper flat pulley after the stress of the V-ribbed belt reaches 170 N / mm. It returned to the position. The slope (average slope) of the region (85 to 140 N / mm) in a relatively linear relationship in the second measurement of the stress-strain curve is again performed by raising and lowering from the initial position again, and the tension of the V-ribbed belt is measured. Calculated as elastic modulus.

The evaluation results are shown in Table 3.

The tensile modulus of elasticity of the V-ribbed belt obtained in Example 2 was 330 N / (mm ·%).

Examples 1 to 3 had high strength retention compared with the comparative example, did not cause peeling or pop out in the high load endurance test, and had high durability.

On the other hand, in Comparative Example 1 (belt containing a single twist of carbon fiber), the tensile strength was low, and peeling occurred at the interface between the core wire and the adhesive rubber in the high load endurance test, and the durability was low. . In addition, in Comparative Example 2 in which the fineness of the carbon fiber is made larger than that of Comparative Example 1, although the tensile strength before the bending fatigue test is high, the strength retention is low and the core wire protrudes from the side of the belt in the high load durability test (Pop out) occurred and durability was low. Thus, in the case of a single carbon fiber twisting yarn, it was not possible to improve both the bending fatigue resistance and the adhesion.

Comparative Example 3 (a belt having a core-sheath structure as in the example, a fine diameter of the sheath yarn is small, and a cord including a core of a cord having a yarn diameter ratio of 0.18) has high strength retention and good bending fatigue resistance. However, in the high load endurance test, peeling occurred at the interface between the core wire and the adhesive rubber layer, and the adhesion could not be improved.

In Comparative Example 4 (a belt having a core-sheath structure as in the example, a large yarn fineness, and a cord including a cord having a cord diameter of 0.43), occurrence of peeling and popout in the high load durability test is Although the adhesion was good, the strength retention was low and the bending fatigue resistance could not be improved.

In Examples 1 and 2 (total fineness of core yarn is 400 tex), resistance to bending fatigue and adhesiveness can be compatible, and durability is at a level at which there is no problem. Example 3 (the total fineness of the core yarn is as thin as 200 tex) has a slightly lower tensile strength before the bending fatigue test compared to the other examples, but is particularly excellent in the bending fatigue resistance, and the bending fatigue test The subsequent tensile strength was at a level comparable to that of Examples 1 and 2. Therefore, it is shown that the fineness of the core yarn can be appropriately selected in accordance with the required level of bending fatigue resistance.

The friction transmission belt (V-ribbed belt, etc.) of the present invention can be used as various power transmission belts, for example, V-ribbed belts used for driving accessories of automobile engines, but can transmit power with a narrow belt width and has excellent durability. Therefore, it can be particularly suitably used as a V-ribbed belt for driving an ISG mounted engine which generates high dynamic tension.

Although the invention has been described in detail and with reference to specific embodiments, it will be apparent to those skilled in the art that various modifications and variations can be made without departing from the spirit and scope of the invention.
This application is based on Japanese Patent Application No. 2017-235161 filed on Dec. 7, 2017 and Japanese Patent Application No. 2018-017176 filed on October 26, 2018, the contents of which are incorporated herein by reference. It is captured.

1 ... core wire (or twist cord)
2 Core thread 3 Sheath thread 12 Compression rubber layer 13 V-rib portion 14 Bonding rubber layer 15 Stretch layer

Claims

A friction transmission belt comprising a core wire, wherein the core wire comprises a core yarn comprising a high modulus fiber and a plurality of sheath yarns disposed around the core yarn and comprising a low modulus fiber. The friction transmission belt, wherein the cord is over-twisted, and the ratio of the average diameter of the sheath yarn to the average diameter of the core yarn is 0.2 to 0.4.
The friction transmission belt according to claim 1, wherein the total fineness of the sheath yarn is 30 to 80 tex.
The friction transmission belt according to claim 1 or 2, wherein the sheath yarn has an average diameter of 0.13 to 0.25 mm.
The twisted yarn according to any one of claims 1 to 3, wherein the sheath yarn is a twisted yarn having a lower twist, and the cord is a twisted yarn cord in which 11 to 19 sheath yarns are twisted with respect to one core yarn. Friction transmission belt.
The friction transmission belt according to any one of claims 1 to 4, wherein the core wire includes a core wire of an S twist cord and a core wire of a Z twist cord embedded at a predetermined distance in the rubber layer.
The friction transmission belt according to claim 4 or 5, wherein twist directions of the first twist and the second twist are the same.
The friction transmission belt according to any one of claims 1 to 6, wherein the high modulus fiber comprises carbon fiber and the low modulus fiber comprises glass fiber.
The adhesive component adheres to the surface of at least a portion of the high modulus fiber or the surface of at least a portion of the low modulus fiber, and the rubber component adheres to the surface of at least a portion of the cord. The friction transmission belt according to any one of the preceding claims.
The friction transmission belt according to any one of claims 1 to 8, which is a V-ribbed belt.
The friction transmission belt according to any one of claims 1 to 9, having a tensile elastic modulus of 240 to 500 N / (mm ·%).
The friction transmission belt according to any one of claims 1 to 10 mounted on a belt-type ISG drive mounted engine in which a dynamic tension of 85 N / mm or more acts per 1 mm width of the belt.
A friction drive belt is manufactured by the steps of forming a rubber sheet formed of an unvulcanized rubber composition and having a core embedded therein into a predetermined shape and vulcanizing the formed product. In the method, a plurality of sheath yarns containing low elastic modulus fibers are arranged around the core yarn containing high elastic modulus fibers as the core wire, and are twisted in a sheath, with respect to the average diameter of the core yarns. A method of manufacturing a friction transmission belt using a core wire containing a cord having a ratio of average yarn diameter of 0.2 to 0.4.
A plurality of sheath yarns containing low modulus fibers are arranged around a core yarn comprising high modulus fibers, and it is a top-twisted cord, wherein the ratio of the average diameter of the sheath yarn to the average diameter of the core yarns is The code is 0.2-0.4.
A method of producing a cord by arranging a plurality of sheath yarns containing low elastic modulus fibers around a core yarn containing high elastic modulus fibers, and producing a cord, wherein the average of sheath yarns relative to the average diameter of the core yarns A method of producing a cord, wherein the diameter ratio is 0.2 to 0.4.
The method for producing a cord according to claim 14, wherein the core yarn and the sheath yarn are respectively subjected to an adhesion treatment, and the over-twisted cord is coated with a rubber composition containing a rubber component.