阅读说明：本技术 多楔带及其制造方法 (V-ribbed belt and method for manufacturing same ) 是由 滨本浩平 西山健 于 2018-05-23 设计创作，主要内容包括：本发明涉及一种多楔带,其摩擦传动面由纬编多层针织布构成,其特征在于,上述纬编多层针织布含有纤维素类天然短纤纱、聚酯类复合纱和聚酰胺类的纱,在上述摩擦传动面侧的层中至少配置有上述纤维素类天然短纤纱和上述聚酰胺类的纱。(The present invention relates to a V-ribbed belt having a friction transmission surface formed from a weft-knitted multilayer knitted fabric, characterized in that the weft-knitted multilayer knitted fabric contains a cellulose-based natural staple yarn, a polyester-based composite yarn, and a polyamide-based yarn, and at least the cellulose-based natural staple yarn and the polyamide-based yarn are arranged in a layer on the friction transmission surface side.)

1. A V-ribbed belt, the friction drive surface of which is composed of weft-knitted multi-layer knitted fabric, is characterized in that,

the weft-knitted multilayer fabric comprises a cellulose natural spun yarn, a polyester composite yarn and a polyamide yarn, and at least the cellulose natural spun yarn and the polyamide yarn are arranged in the layer on the friction transmission surface side.

2. The v-ribbed belt according to claim 1, characterized in that the content of the polyamide-based yarn in the weft-knitted multilayer knitted fabric is 5 to 60 mass%.

3. The v-ribbed belt according to claim 1 or 2, wherein the content of the cellulose-based natural spun yarn in the weft-knitted multilayer knitted fabric is 5 to 60% by mass.

4. The v-ribbed belt according to claim 1 or 2, wherein in said weft-knitted multilayer fabric, the mass ratio of said polyamide-based yarn to said cellulose-based natural spun yarn is 5: 95-95: 5.

5. the v-ribbed belt according to any one of claims 1 to 4, wherein said polyester-based composite yarn contained in said weft-knitted multilayer fabric is a bulky yarn composed of two or more polymers having different heat shrinkages.

6. The v-ribbed belt according to any one of claims 1 to 5, wherein said polyester-based composite yarn contained in said weft-knitted multilayer knitted fabric is a conjugated yarn containing polyethylene terephthalate (PET).

7. The v-ribbed belt according to any one of claims 1 to 6, characterized in that said polyamide-based yarns contained in said weft-knitted multilayer fabric comprise nylon or aramid fibers.

8. The v-ribbed belt according to any one of claims 1 to 7, characterized in that the yarns constituting said weft-knitted multilayer knitted fabric are each twisted with filaments and fibers.

9. The v-ribbed belt according to any one of claims 1 to 8, characterized in that said weft-knitted multilayer knitted fabric is free of polyurethane.

10. The v-ribbed belt according to any one of claims 1 to 9, wherein the thickness of the weft-knitted multilayer fabric covering the friction transmission surface is 0.6mm or more.

11. The v-ribbed belt according to any one of claims 1 to 10, wherein the cellulose-based natural staple yarn and the polyamide-based yarn are arranged so as to be uniformly dispersed in the layer on the friction transmission surface side of the weft-knitted multilayer knitted fabric.

12. The V-ribbed belt according to any one of claims 1 to 11,

the V-ribbed belt contains rubber as a constituent element,

the friction transmission surface side of the rubber is coated with the weft-knitted multilayer knitted fabric,

there is no bleeding of the rubber from the weft-knitted multilayer knitted fabric to the friction transmission surface.

13. A method for manufacturing a V-ribbed belt according to any one of claims 1 to 12, wherein,

covering an unvulcanized sheet for compression layer with a tubular weft-knitted multilayer fabric obtained by joining both ends of the weft-knitted multilayer fabric; or both ends of the weft-knitted multilayer knitted fabric are joined to an unvulcanized sheet for a compression layer.

Technical Field

The present invention relates to a v-ribbed belt with a friction transmission surface coated with a knitted fabric, and a method for manufacturing the same.

Background

The power transmission belt is widely used for power transmission driven by auxiliary machines such as an air compressor and an alternator of an automobile. In recent years, there has been a strong demand for quietness, and particularly in a drive device of an automobile, a sound other than an engine sound is regarded as an abnormal noise, and therefore, a countermeasure against the generation of the noise is required.

The noise generated by the belt is caused by a slip sound generated when the belt and the pulley slip under a high load condition due to a large fluctuation in the belt speed. Particularly, when water enters the engine room during running in a rainy day or the like and water adheres between the belt and the pulley, the friction coefficient of the belt is reduced, and a slip sound may often occur.

To solve such a problem, a measure is known in which the frictional transmission surface of the belt is covered with a knitted fabric made of fibers. For example, in patent document 1, for the purpose of reducing the difference between the friction coefficients of the belt in the dry state and the wet state, a knitted fabric is woven from a bulky polyester composite yarn and a cellulose-based natural spun yarn, and water is rapidly absorbed by the cellulose-based natural spun yarn having excellent water absorption property, thereby suppressing the reduction in the friction coefficient in the wet state and improving the water injection noise resistance.

Disclosure of Invention

Problems to be solved by the invention

However, since the cellulose-based natural spun yarn has low abrasion resistance, the cellulose-based natural spun yarn is abraded with use, and the water absorption property is lowered, and the friction coefficient in a wet state is lowered, whereby the water injection noise generation resistance may not be maintained for a sufficiently long period of time.

Accordingly, an object of the present invention is to provide a v-ribbed belt in which a friction transmission surface is coated with a knitted fabric having excellent wear resistance, for the purpose of maintaining water injection noise generation resistance over a long period of time, and a method for manufacturing the v-ribbed belt.

Means for solving the problems

The present invention for solving the above problems is a v-ribbed belt whose friction transmission surface is composed of a weft-knitted multilayer knitted fabric, characterized in that the weft-knitted multilayer knitted fabric contains a cellulose-based natural staple yarn, a polyester-based composite yarn, and a polyamide-based yarn, and at least the cellulose-based natural staple yarn and the polyamide-based yarn are arranged in a layer on the friction transmission surface side.

By incorporating a cellulose-based natural spun yarn in the weft-knitted multilayer knitted fabric covering the friction transmission surface, the water absorption of the v-ribbed belt can be improved, and the water injection noise resistance can be improved. Further, by incorporating the polyester composite yarn in the weft-knitted multilayer knitted fabric, the stretchability of the weft-knitted multilayer knitted fabric can be improved, and the adaptability of the weft-knitted multilayer knitted fabric to the V-shaped rib when the V-shaped rib is formed on the belt by the mold can be improved. Further, by incorporating polyamide-based yarns into the weft-knitted multilayer fabric, abrasion resistance can be improved, and abrasion of the cellulose-based natural staple yarns can be suppressed, so that water injection noise generation resistance can be maintained for a long period of time.

In addition, since the stretchability is improved by weft knitting the knitted fabric covering the friction transmission surface, it is possible to prevent defective shapes of the rib portions from being generated in the manufacturing process of the V-ribbed belt in which the V-shaped rib portions are formed on the belt by the mold. Further, by using a multilayer structure for the knitted fabric, it is possible to suppress the rubber, which is a constituent element of the v-ribbed belt, from bleeding out through the knitted fabric to the friction transmitting surface side, and to reduce the difference between the friction coefficient in the dry state and the friction coefficient in the wet state of the friction transmitting surface, and therefore, the water injection noise resistance can be improved.

Further, by disposing the cellulose-based natural spun yarn having high water absorbability in the layer on the friction transmission surface side of the v-ribbed belt, water that has permeated between the pulley and the v-ribbed belt can be absorbed quickly and the friction coefficient can be stabilized (reduction in the friction coefficient in a wet state is suppressed), and therefore, the water injection noise resistance can be improved. Further, by disposing the polyamide-based yarn having high abrasion resistance in the layer on the friction transmission surface side, abrasion of the cellulose-based natural spun yarn can be suppressed, and water injection noise generation resistance can be maintained for a long period of time.

In the present invention, the content of the polyamide-based yarn in the weft-knitted multilayer knitted fabric of the v-ribbed belt may be 5 to 60% by mass.

With the above configuration, the wear resistance can be improved without impairing the water injection noise resistance of the v-ribbed belt. When the content of the polyamide-based yarn is less than 5% by mass, the abrasion resistance may be reduced. When the content of the polyamide-based yarn is more than 60% by mass, water absorption may be reduced, and water injection noise generation resistance may be reduced. In the weft-knitted multilayer fabric, the content of the polyamide-based yarn is preferably 15 to 60 mass%, more preferably 20 to 55 mass%, and still more preferably 20 to 40 mass%.

In the weft-knitted multilayer fabric of the v-ribbed belt, the content of the cellulose-based natural spun yarn may be 5 to 60% by mass.

With the above configuration, the wear resistance can be improved without impairing the water injection noise resistance of the v-ribbed belt. When the content of the cellulosic natural spun yarn is less than 5% by mass, the water absorption may be reduced, and the resistance to generation of water flooding noise may be reduced. When the content of the cellulosic natural spun yarn is more than 60% by mass, abrasion resistance may be reduced. In the weft-knitted multilayer fabric, the content of the cellulose natural spun yarn is preferably 5 to 55 mass%, more preferably 5 to 40 mass%, and still more preferably 20 to 40 mass%.

In the weft-knitted multilayer knitted fabric of the v-ribbed belt, the mass ratio of the polyamide-based yarn to the cellulose-based natural spun yarn may be 5: 95-95: 5.

with the above configuration, the wear resistance can be improved without impairing the water injection noise resistance of the v-ribbed belt. When the content of the polyamide-based yarn is small, the abrasion resistance is reduced; when the content ratio of the polyamide-based yarn is large, water absorption is reduced, and therefore, water injection noise generation resistance is reduced. In the weft-knitted multilayer knitted fabric, the mass ratio of the polyamide-based yarn to the cellulose-based natural staple yarn is preferably 10: 90-90: 10, more preferably 20: 80-80: 20, more preferably 30: 70-70: 30.

in the present invention, in the v-ribbed belt, the polyester composite yarn contained in the weft-knitted multilayer knitted fabric may be a bulky yarn composed of two or more polymers having different heat shrinkage rates.

According to the above configuration, the crimp property is exhibited by the difference in the thermal shrinkage rates of two or more polymers, and the weft-knitted multilayer knitted fabric can be provided with stretchability and bulkiness. Thus, in the process of manufacturing a V-ribbed belt in which V-ribs are formed on a belt by a mold, the adaptability of a weft-knitted multilayer knitted fabric to the V-ribs can be improved. Further, the rubber, which is a constituent element of the v-ribbed belt, can be inhibited from bleeding out to the friction transmission surface side through the knitted fabric, and the difference between the friction coefficient in the dry state and the friction coefficient in the wet state of the friction transmission surface can be reduced, so that the water injection noise resistance can be improved.

In the present invention, in the v-ribbed belt, the polyester-based composite yarn contained in the weft-knitted multilayer knitted fabric may be a conjugated yarn containing polyethylene terephthalate (PET).

By using a conjugate yarn containing polyethylene terephthalate (PET) for the polyester composite yarn contained in the weft-knitted multilayer knitted fabric, the stretchability, bulkiness, and abrasion resistance of the weft-knitted multilayer knitted fabric can be improved. In addition, since the conjugated yarn containing polyethylene terephthalate is excellent in availability, the cost can be reduced.

In the present invention, in the v-ribbed belt, the polyamide-based yarn contained in the weft-knitted multilayer knitted fabric may contain a nylon or an aramid fiber.

Since a weft-knitted multilayer knitted fabric containing nylon or aramid fibers has high abrasion resistance, the effect of suppressing abrasion of cellulosic natural spun yarns is high, and water injection noise generation resistance can be maintained for a long period of time.

In the present invention, in the v-ribbed belt, the yarns constituting the weft-knitted multilayer knitted fabric may be respectively twisted with filaments and fibers.

By bundling filaments and fibers in yarns constituting a weft-knitted multilayer knitted fabric, abrasion resistance is improved. Further, by twisting and collecting the filaments and fibers in the yarns constituting the weft-knitted multilayer knitted fabric, the knitted fabric can be easily knitted, and the filaments and fibers can be suppressed from fluffing, and the appearance quality of the v-ribbed belt can be improved.

In the present invention, in the v-ribbed belt, the weft-knitted multilayer knitted fabric may not contain polyurethane.

Since the weft-knitted multilayer knitted fabric does not contain polyurethane having lower water absorbency and abrasion resistance than the fiber material, the water absorbency and abrasion resistance of the weft-knitted multilayer knitted fabric can be prevented from being lowered. In the above-described configuration, although the stretchability is considered to be poor because the knitted fabric does not contain polyurethane, which is often used, the stretchability can be ensured because the polyester composite yarn having excellent stretchability is contained in the above-described configuration.

In the present invention, the thickness of the weft-knitted multilayer fabric covering the friction transmission surface in the v-ribbed belt may be 0.6mm or more.

By setting the thickness of the weft-knitted multilayer knitted fabric to 0.6mm or more, it is possible to suppress the rubber, which is a constituent element of the V-ribbed belt, from bleeding out through the knitted fabric to the friction transmission surface side, and to reduce the difference between the friction coefficient in the dry state and the friction coefficient in the wet state of the friction transmission surface, and to improve the water injection noise resistance. When the thickness of the weft-knitted multilayered knitted fabric is 0.7mm or more, the rubber, which is a constituent element of the v-ribbed belt, can be more reliably suppressed from bleeding out through the knitted fabric to the friction transmission surface side, and particularly preferably 0.8mm or more. The upper limit of the thickness of the weft-knitted multilayer knitted fabric is not particularly limited, and may be, for example, 1.5mm or less.

In the present invention, the cellulose-based natural staple yarn and the polyamide-based yarn may be uniformly dispersed in the layer of the v-ribbed belt on the friction transmission surface side of the weft-knitted multilayer knitted fabric.

Since the cellulosic natural spun yarn and the polyamide-based yarn are arranged so as to be uniformly dispersed, the polyamide-based yarn is present in the vicinity of the cellulosic natural spun yarn, as compared with a case where a plurality of yarns are arranged together, and therefore, abrasion of the cellulosic natural spun yarn can be more reliably suppressed. Further, since there is no unevenness in water absorption, the water injection noise resistance can be improved.

In the present invention, the ribbed belt may include a rubber as a constituent element, the weft-knitted multilayer knitted fabric may be coated on a friction transmission surface side of the rubber, and the rubber may not bleed out from the weft-knitted multilayer knitted fabric to the friction transmission surface.

When the rubber bleeds out from the weft-knitted multilayer knitted fabric to the friction transmission surface, the water absorption property is lowered, and therefore, the reduction of the friction coefficient in the wet state is increased, and the water injection noise generation resistance is lowered. Therefore, by eliminating the bleeding of rubber from the weft-knitted multilayer knitted fabric to the friction transmission surface, sufficient water absorption can be ensured, and therefore, the water injection noise resistance can be improved. Here, "no bleeding of rubber" means that the area ratio of rubber exposed to the friction transmission surface is less than 5%.

The present invention is the above-described method for producing a v-ribbed belt, wherein a tubular weft-knitted multilayer fabric obtained by joining both ends of the weft-knitted multilayer fabric is covered on an unvulcanized sheet for a compression layer; or both ends of the weft-knitted multilayer knitted fabric are joined to an unvulcanized sheet for a compression layer.

When a tubular seamless (non-joint) weft-knitted multilayer fabric is to be coated on a sheet for a compression layer, a weft-knitted multilayer fabric having a circumferential length corresponding to a tape length needs to be prepared, and therefore, a large number of semi-finished products need to be prepared in order to cope with various tape lengths. On the other hand, in the method of joining both ends of the weft-knitted multilayer knitted fabric as in the above-described method, the circumferential length of the weft-knitted multilayer knitted fabric can be adjusted in situ according to the tape length, and therefore, it is not necessary to prepare a large amount of semi-finished products.

Effects of the invention

A V-ribbed belt capable of maintaining water injection noise resistance for a long period of time by covering a friction transmission surface with a knitted fabric having excellent abrasion resistance, and a method for producing the V-ribbed belt.

Drawings

Fig. 1 is a schematic perspective view illustrating an example of a belt drive device using the v-ribbed belt of the present invention.

Fig. 2 is a cross-sectional view of the v-ribbed belt taken along section a-a' of fig. 1.

Fig. 3 is an explanatory view showing an example (a) in which cellulose-based natural staple yarn and polyamide-based yarn are uniformly dispersed and an example (B) in which the yarns are not uniformly dispersed in a knitted fabric.

Fig. 4 is a conceptual diagram illustrating a method of manufacturing a v-ribbed belt.

Fig. 5 is a conceptual diagram illustrating a friction coefficient measurement test in a dry state (a) and a wet state (b).

Fig. 6 is a conceptual diagram illustrating a running noise occurrence evaluation test.

Detailed Description

Hereinafter, an example of an embodiment of the present invention will be described with reference to the drawings. Fig. 1 shows an example of a belt drive device for driving an auxiliary machine using a v-ribbed belt 1 of the present invention. This belt transmission device is the simplest example including one drive pulley 21 and one driven pulley 22, and the v-ribbed belt 1 is wound around and suspended between these drive pulley 21 and driven pulley 22. In the endless V-ribbed belt 1, a plurality of V-shaped ribs 2 extending in the belt circumferential direction are formed on the inner circumferential side, and a plurality of V-shaped grooves 23 for fitting the respective ribs 2 of the V-ribbed belt 1 are provided on the outer circumferential surfaces of the drive pulley 21 and the driven pulley 22.

(construction of the V-ribbed belt 1)

As shown in fig. 2, the V-ribbed belt 1 includes an extended layer 3 forming a belt back surface on an outer peripheral side, a compressed layer 4 provided on an inner peripheral side of the extended layer 3, and a core wire 5 embedded between the extended layer 3 and the compressed layer 4 and extending in a belt circumferential direction, a plurality of V-shaped ribs 2 extending in the belt circumferential direction are formed on the compressed layer 4, and a surface of the rib 2 serving as a friction transmission surface is covered with a knitted fabric 6. As described later, the extension layer 3 and the compression layer 4 are each formed of a rubber composition. An adhesive layer may be provided between the extension layer 3 and the compression layer 4 as necessary. The adhesive layer is provided for the purpose of improving the adhesiveness of the core wire 5 to the extension layer 3 and the compression layer 4, and is not essential. The form of the adhesive layer may be a form in which the entire core wire 5 is embedded in the adhesive layer, or a form in which the core wire 5 is embedded between the adhesive layer and the extension layer 3 or between the adhesive layer and the compression layer 4.

Examples of the rubber component of the rubber composition forming the compression layer 4 include vulcanizable or crosslinkable rubbers, for example, diene rubbers (natural rubber, isoprene rubber, butadiene rubber, chloroprene rubber, styrene-butadiene rubber, nitrile rubber, hydrogenated nitrile rubber, mixed polymers of hydrogenated nitrile rubber and metal salt of unsaturated carboxylic acid, etc.), ethylene- α -olefin elastomers, chlorosulfonated polyethylene rubber, alkylated chlorosulfonated polyethylene rubber, epichlorohydrin rubber, acrylic rubber, silicone rubber, urethane rubber, fluororubber, etc.

Among them, it is preferable to form an unvulcanized rubber layer using a rubber composition containing sulfur or an organic peroxide and vulcanize or crosslink the unvulcanized rubber layer, and an ethylene- α -olefin elastomer (ethylene- α -olefin rubber) is particularly preferable from the viewpoint of not containing harmful halogen, having ozone resistance, heat resistance, cold resistance, and being excellent in economical efficiency. Examples of the ethylene- α -olefin elastomer include ethylene- α -olefin rubbers (e.g., ethylene-propylene rubbers) and ethylene- α -olefin-diene rubbers (e.g., ethylene-propylene-diene copolymers). Examples of the α -olefin include propylene, butene, pentene, methylpentene, hexene, and octene. These α -olefins may be used alone or in combination of two or more. Examples of the diene monomer to be used as a raw material of the diene monomer include non-conjugated diene monomers such as dicyclopentadiene, methylene norbornene, ethylidene norbornene, 1, 4-hexadiene, and cyclooctadiene. These diene monomers may be used alone or in combination of two or more.

In the ethylene- α -olefin elastomer, the ratio of ethylene to α -olefin (the mass ratio of the former/the latter) may be 40/60 to 90/10, preferably 45/55 to 85/15, and more preferably 55/45 to 80/20. The proportion of the diene may be selected from the range of 4 to 15% by mass, and for example, may be set to 4.2 to 13% by mass, and preferably may be set to 4.4 to 11.5% by mass. The iodine value of the ethylene- α -olefin elastomer containing a diene component may be set to, for example, 3 to 40, preferably 5 to 30, and more preferably 10 to 20. When the iodine value is too small, vulcanization of the rubber composition is insufficient, abrasion or adhesion is likely to occur, and when the iodine value is too large, scorching time of the rubber composition becomes short, handling becomes difficult, and heat resistance tends to decrease. As a method for measuring an iodine value, an excess amount of iodine is added to a measurement sample to completely react the sample (reaction between iodine and an unsaturated bond), and the amount of residual iodine is quantified by redox titration to determine an iodine value.

Examples of the organic peroxide for crosslinking the unvulcanized rubber layer include diacyl peroxides, peroxyesters, dialkyl peroxides (dicumyl peroxide, t-butylcumyl peroxide, 1-dibutylperoxy-3, 3, 5-trimethylcyclohexane, 2, 5-dimethyl-2, 5-di (t-butylperoxy) hexane, 1, 3-bis (t-butylperoxyisopropyl) benzene, di-t-butyl peroxide, and the like). These organic peroxides may be used alone or in combination of two or more. Further, the temperature range in which the half-life of the organic peroxide based on thermal decomposition is 1 minute may be from about 150 ℃ to about 250 ℃, and preferably may be from about 175 ℃ to about 225 ℃.

The proportion of the vulcanizing agent or the crosslinking agent (particularly, the organic peroxide) in the unvulcanized rubber layer may be set to 1 to 10 parts by mass, preferably 1.2 to 8 parts by mass, and more preferably 1.5 to 6 parts by mass in terms of solid content, relative to 100 parts by mass of the rubber component (e.g., ethylene- α -olefin elastomer).

The rubber composition may contain a vulcanization accelerator. Examples of the vulcanization accelerator include thiuram accelerators, thiazole accelerators, sulfenamide accelerators, bismaleimide accelerators, and urea accelerators. These vulcanization accelerators may be used alone or in combination of two or more. The proportion of the vulcanization accelerator (in the case of two or more types in combination, the total amount is defined, and the same applies to the case of two or more types in combination in the following) may be set to 0.5 to 15 parts by mass, preferably 1 to 10 parts by mass, and more preferably 2 to 5 parts by mass in terms of solid content, relative to 100 parts by mass of the rubber component.

In addition, the rubber composition may further contain a co-crosslinking agent (crosslinking aid or co-vulcanizing agent) in order to increase the degree of crosslinking, prevent adhesive abrasion, and the like. Examples of the co-crosslinking agent include conventional crosslinking aids, for example, polyfunctional (iso) cyanurate (triallyl isocyanurate, triallyl cyanurate, etc.), polydiene (1, 2-polybutadiene, etc.), metal salts of unsaturated carboxylic acids ((e.g., zinc (meth) acrylate, magnesium (meth) acrylate, etc.), oximes (quinone dioxime, etc.), guanidines (diphenylguanidine, etc.), polyfunctional (meth) acrylates (ethylene glycol di (meth) acrylate, butanediol di (meth) acrylate, trimethylolpropane tri (meth) acrylate, etc.), bismaleimides (N, N' -m-phenylene bismaleimide, etc.), and the like. These crosslinking aids may be used alone or in combination of two or more. The proportion of the crosslinking assistant may be set to 0.01 to 10 parts by mass, preferably 0.05 to 8 parts by mass, in terms of solid content, per 100 parts by mass of the rubber component.

The rubber composition may contain short fibers as needed. Examples of the short fibers include cellulose fibers (cotton, rayon, etc.), polyester fibers (PET, PEN fibers, etc.), aliphatic polyamide fibers (nylon 6 fibers, nylon 66 fibers, nylon 46 fibers, etc.), aromatic polyamide fibers (para-aramid fibers, meta-aramid fibers, etc.), vinylon fibers, and poly-p-phenylene benzobisbibenzamide fibers

Azole (PBO) fibers, and the like. These short fibers may be subjected to conventional adhesion treatment or surface treatment, for example, treatment with RFL liquid or the like, in order to improve dispersibility and adhesiveness in the rubber composition. The proportion of the short fibers may be set to 1 to 50 parts by mass, preferably 5 to 40 parts by mass, and more preferably 10 to 35 parts by mass, per 100 parts by mass of the rubber component.

The rubber composition may further contain, as required, conventional additives, for example, a vulcanization aid, a vulcanization retarder, a reinforcing agent (such as carbon black or silica such as hydrated silica), a filler (such as clay, calcium carbonate, talc or mica), a metal oxide (such as zinc oxide, magnesium oxide, calcium oxide, barium oxide, iron oxide, copper oxide, titanium oxide or aluminum oxide), a plasticizer (such as paraffin oil, naphthene oil or oil such as processing oil), a processing agent or a processing aid (such as stearic acid, metal stearate, wax, paraffin or fatty acid amide), an antiaging agent (such as antioxidant, heat aging inhibitor, flex inhibitor or ozone deterioration inhibitor), a coloring agent, a tackifier, a coupling agent (such as silane coupling agent), a stabilizer (such as ultraviolet absorber, antioxidant, ozone deterioration inhibitor or heat stabilizer), a lubricant (such as graphite or graphite, a lubricant (such as a silicone rubber, a rubber, molybdenum disulfide, ultra-high molecular weight polyethylene, etc.), flame retardants, antistatic agents, etc. The metal oxide may function as a crosslinking agent. These additives may be used alone or in combination of two or more. The proportion of these additives is selected from a range conventionally used depending on the kind, and for example, the proportion of the reinforcing agent (carbon black, silica, etc.) may be set to 10 to 200 parts by mass (preferably 20 to 150 parts by mass), the proportion of the metal oxide (zinc oxide, etc.) may be set to 1 to 15 parts by mass (preferably 2 to 10 parts by mass), the proportion of the plasticizer (oil such as paraffin oil, etc.) may be set to 1 to 30 parts by mass (preferably 5 to 25 parts by mass), and the proportion of the processing agent (stearic acid, etc.) may be set to 0.1 to 5 parts by mass (preferably 0.5 to 3 parts by mass) with respect to 100 parts by mass of the rubber component.

The extension layer 3 may be formed of the same rubber composition (rubber composition containing a rubber component such as an ethylene- α -olefin elastomer) as the compression layer 4, or may be formed using a cloth (reinforcing cloth) such as canvas. Examples of the reinforcing fabric include woven fabric, canvas, knitted fabric, and nonwoven fabric. Among them, woven fabrics woven by plain weaving, twill weaving, satin weaving, etc., wide canvas and knitted fabrics in which the crossing angle between warp and weft is about 90 ° to about 130 ° are preferable. As the fibers constituting the reinforcing fabric, the same fibers as the short fibers described above can be used. The reinforcing cloth may be treated with RFL liquid (dipping treatment or the like) and then subjected to coating treatment or the like to prepare a rubber-containing canvas.

The extension layer 3 is preferably formed of the same rubber composition as the compression layer 4. As the rubber component of the rubber composition, a rubber of the same system as that of the rubber component of the compression layer 4 or the same kind of rubber is often used. The proportions of additives such as a vulcanizing agent, a crosslinking agent, a co-crosslinking agent, and a vulcanization accelerator may be selected from the same ranges as those of the rubber composition of the compression layer 4.

In order to suppress generation of abnormal noise due to adhesion of the back rubber at the time of back driving, the rubber composition of the extension layer 3 may contain the same short fiber as that of the compression layer 4. The short fibers may be linear or partially curved (e.g., milled fibers described in jp 2007-120507 a). While there is a possibility that cracks may occur in the extending layer 3 in the belt circumferential direction during running of the v-ribbed belt 1 and the v-ribbed belt 1 may be broken, this can be prevented by orienting the short fibers in the belt width direction or in a random direction. In addition, in order to suppress generation of abnormal noise at the time of back surface driving, an uneven pattern may be provided on the front surface (tape back surface) of the extension layer 3. The uneven pattern includes a knitted fabric pattern, a woven fabric pattern, a curtain fabric pattern, an embossed pattern (for example, a corrugated pattern), and the like, and the size and the depth are not particularly limited.

The core wire 5 is not particularly limited, and a cord formed of polyester fibers (polybutylene terephthalate fibers, polyethylene terephthalate fibers, polypropylene terephthalate fibers, polyethylene naphthalate fibers, and the like), aliphatic polyamide (nylon) fibers (nylon 6 fibers, nylon 66 fibers, nylon 46 fibers, and the like), aromatic polyamide (aramid) fibers (copolymerized p-phenylene-3, 4' -oxydiphenylene-terephthalamide fibers, polyparaphenylene terephthalamide fibers, and the like), polyarylate fibers, glass fibers, carbon fibers, PBO fibers, and the like can be used. These fibers may be used alone or in combination of two or more. These fibers are appropriately selected according to the expansion rate of the flexible jacket 51 described later. For example, in the case of high elongation such as an expansion ratio exceeding 2%, polyester fibers (particularly low-elasticity polybutylene terephthalate fibers) and nylon fibers (particularly nylon 66 fibers and nylon 46 fibers) having a low elastic modulus are preferable. This is because, even if the flexible jacket 51 expands, fibers having a high elastic modulus, such as aramid fibers and PBO fibers, cannot sufficiently extend, and the pitch line of the core wire 5 embedded in the v-ribbed belt 1 is unstable or the shape of the rib 2 cannot be appropriately formed. Therefore, in order to use a fiber having a high elastic modulus, the expansion rate of the flexible jacket 51 is preferably set to be low (for example, about 1%).

Since the knitted fabric 6 is weft knitted with excellent stretchability, it can more easily follow the friction transmission surface having the ribs 2 formed with irregularities (the ribs 2 are less likely to have a defective shape). The knitted fabric 6 is applied to a multilayer knitting because it has a large thickness and excellent water absorption, can more reliably prevent the bleeding of the rubber component of the compression layer 4, and can obtain desired properties by changing the exposure ratio of the yarn on the friction transmission surface side and the compression layer 4 side. In weft knitting, as the knitted fabric 6 to be knitted into a plurality of layers, a circular interlock structure (ス ム ー ス st), an interlock structure (イ ン タ ー ロ ッ ク st), a double interlock structure (ダ ブ ル リ ブ st), a single-sided uneven structure, a roman structure, a milano interlock structure, a double plain structure, a gill stitch structure (a surface gill stitch, a back gill stitch, a double gill stitch), and the like can be cited.

The knitted fabric 6 is woven to include polyester composite yarn, natural cellulose staple yarn (for example, cotton yarn), and polyamide yarn. Further, the knitted fabric 6 is knitted so that at least a cellulose-based natural spun yarn and a polyamide-based yarn are arranged in a layer on the friction transmission surface side (the surface side in contact with the driving pulley 21 and the driven pulley 22) where the knitted fabric is knitted in a plurality of layers. That is, the polyester composite yarn is not necessarily required for the layer on the friction transmission surface side of the knitted fabric 6. The knitted fabric 6 may further contain fibers other than polyester composite yarn, cellulose natural spun yarn, and polyamide yarn. The total content of the polyester composite yarn, the cellulose natural spun yarn, and the polyamide yarn in the knitted fabric 6 is preferably 80 mass% or more. The total content of the cellulosic natural spun yarn and the polyamide yarn in the layer on the friction transmission surface side of the knitted fabric 6 is preferably 70 mass% or more.

In the present embodiment, the polyester composite yarn is a bulked yarn. The bulked yarn is a processed yarn obtained by increasing the volume of a cross section by crimping (crimpability) fibers or by covering a core yarn with another yarn. The bulked yarn includes a conjugate yarn, a covering yarn, a crimped yarn, a wool-like yarn, a taslon yarn, and a union yarn, and the polyester composite yarn as the bulked yarn is preferably a conjugate yarn or a covering yarn.

The conjugate yarn preferably has a cross-sectional structure obtained by laminating two or more polymers having different heat shrinkages in the axial direction of the fiber. When heat is applied to the conjugated yarn having such a structure during production or processing, the difference in shrinkage rate (thermal shrinkage rate) between the polymers causes crimp, and a bulked yarn is formed. Examples of the yarn include a composite yarn (PTT/PET conjugated yarn) obtained by conjugating polytrimethylene terephthalate (PTT) and polyethylene terephthalate (PET), and a composite yarn (PBT/PET conjugated yarn) obtained by conjugating polybutylene terephthalate (PBT) and polyethylene terephthalate (PET). By using a conjugate yarn containing polyethylene terephthalate (PET) as the polyester composite yarn as described above, the stretchability, bulkiness, and abrasion resistance of the knitted fabric 6 can be improved. In addition, since the conjugated yarn containing polyethylene terephthalate is excellent in availability, the cost can be reduced. The core yarn is a yarn in which the volume of the cross section of the entire yarn is increased by covering (covering) the periphery of the core yarn with another yarn. For example, there are a composite yarn (PET/PU core yarn) obtained by coating polyethylene terephthalate (PET) on the surface of a Polyurethane (PU) yarn having excellent stretchability as a core, and a composite yarn (PA/PU core yarn) obtained by coating Polyamide (PA) on the surface of a PU yarn as a core. Among these composite yarns, a PTT/PET conjugated yarn excellent in stretchability and abrasion resistance is preferable.

By constituting the polyester composite yarn with the bulked yarn composed of two or more polymers having different heat shrinkage rates as described above, the crimpability can be expressed by the difference in heat shrinkage rates of the two or more polymers, and the knitted fabric 6 can be provided with stretchability and bulkiness. Accordingly, in the manufacturing process of forming the V-shaped ribs 2 on the V-ribbed belt 1 by the mold (the inner mold 52 and the outer mold 53) described later, the adaptability of the knitted fabric 6 to the V-shaped ribs 2 can be improved, the rubber component of the compression layer 4 can be suppressed from seeping out to the friction transmission surface side via the knitted fabric 6, and the difference between the friction coefficient in the dry state and the friction coefficient in the wet state of the friction transmission surface can be reduced, so that the water injection noise resistance can be improved.

Examples of the cellulose-based natural staple fiber yarn include yarns obtained by spinning natural plant-derived cellulose fibers (pulp fibers) such as bamboo fibers, sugar cane fibers, hair fibers (cotton linter), kapok fibers, etc.), bast fibers (hemp, paper mulberry, daphne giraldii, etc.), leaf fibers (manila hemp, new zealand hemp, etc.), etc., animal-derived cellulose fibers such as wool, silk, ecthyma cellulose, etc., bacterial cellulose fibers, algal cellulose, etc. Among these, cotton fibers are preferred from the viewpoint of particularly excellent water absorption properties.

In the knitted fabric 6, when the content of the cellulose-based natural spun yarn is less than 5% by mass, the water absorption property may be lowered and the water injection noise generation resistance may be lowered. When the content of the cellulosic natural spun yarn is more than 60% by mass, the abrasion resistance may be reduced. Therefore, in the present embodiment, the content of the cellulose-based natural spun yarn is set to 5 to 60 mass%. In the knitted fabric 6, the content of the cellulosic natural spun yarn is preferably 5 to 55 mass%, more preferably 5 to 40 mass%, and still more preferably 20 to 40 mass%. By setting the above range, the wear resistance can be improved without impairing the water injection noise generation resistance of the v-ribbed belt 1.

Examples of the material of the polyamide-based yarn include aliphatic polyamide (nylon), aromatic polyamide (aramid), and the like. By using an aromatic polyamide (aramid), higher abrasion resistance can be obtained, but even with a relatively inexpensive nylon, abrasion resistance is improved. The polyamide-based yarn may be a filament yarn formed by bundling long fibers or a spun yarn (spun yarn) formed by spinning short fibers (staple). In the case of the filament yarn, the yarn may be an untwisted yarn obtained by doubling filaments, or a twisted yarn obtained by twisting the doubled filaments, and the twisted yarn is preferable from the viewpoint of improving abrasion resistance and workability in knitting.

In the knitted fabric 6, when the content of the polyamide-based yarn is less than 5% by mass, the abrasion resistance may be reduced. When the content of the polyamide-based yarn is more than 60% by mass, water absorption may be reduced, and water injection noise generation resistance may be reduced. Therefore, in the present embodiment, the content of the polyamide-based yarn is set to 5 to 60 mass%. The content of the polyamide-based yarn in the knitted fabric 6 is preferably 15 to 60 mass%, more preferably 20 to 55 mass%, and still more preferably 20 to 40 mass%. By setting the above range, the wear resistance can be improved without impairing the water injection noise generation resistance of the v-ribbed belt 1.

In the knitted fabric 6 of the present embodiment, the mass ratio of the polyamide-based yarn to the cellulose-based natural spun yarn is set to 5: 95-95: 5 in the above range. This is because, when the content ratio of the polyamide-based yarn is less than the range described on the left side, the abrasion resistance may be reduced, and when it is more than the range described on the left side, the water absorption may be reduced, and the water injection noise generation resistance may be reduced. In the knitted fabric 6, the mass ratio of the polyamide-based yarn to the cellulose-based natural spun yarn is preferably 10: 90-90: 10, more preferably 20: 80-80: 20, more preferably 30: 70-70: 30, or less. By setting the above range, the wear resistance can be improved without impairing the water injection noise generation resistance of the v-ribbed belt 1.

In the knitted fabric 6, the cellulosic natural spun yarn and the polyamide yarn are preferably arranged so as to be uniformly dispersed. In the present embodiment, since the abrasion of the cellulosic natural spun yarn can be suppressed by containing at least both of the cellulosic natural spun yarn and the polyamide-based yarn in the layer on the friction transmission surface side (the surface side in contact with the driving pulley 21 and the driven pulley 22) in which the knitted fabric 6 is woven in multiple layers, an effect of maintaining the resistance to the generation of water injection noise for a long period of time is exhibited, and this effect can be remarkably obtained when the polyamide-based yarn is located in the vicinity of the cellulosic natural spun yarn (a) (uniformly dispersed and arranged). For example, (the number of polyamide-based yarns: the number of cellulose-based natural staple fibers) is 1: in the case of 1, it is preferable to alternately weave the yarns one by one. However, when the yarn is knitted so that 10 polyamide yarns and 10 cellulose natural spun yarns are arranged, the cellulose natural spun yarn located at a position far from the polyamide yarns is easily abraded, and thus the water injection noise generation resistance is easily lowered.

Specifically, 1 polyamide-based yarn was knitted for 2 natural cellulose staple yarns, with the mass ratio of the natural cellulose staple yarns being 40% and the mass ratio of the polyamide-based yarns being 20% based on the mass of the entire knitted fabric, and the basis weights of the yarns being the same. In this case, for example, when a 24-ply knitting machine is used, since the polyamide-based yarn is located in the vicinity of the cellulose-based natural spun yarn, the abrasion of the cellulose-based natural spun yarn can be more reliably suppressed, compared to when 16 plies of cellulose-based natural spun yarn and 8 plies of polyamide-based yarn are arranged together (see fig. 3(B)) and when 2 plies of cellulose-based natural spun yarn and 1 ply of polyamide-based yarn are arranged repeatedly 8 times (see fig. 3 (a)). Further, since there is no unevenness in water absorption, the water injection noise resistance can be improved. In the present specification and claims, "cellulose-based natural staple yarn and polyamide-based yarn are uniformly dispersed" means that at least 1 polyamide-based yarn is contained in 12 adjacent yarns.

The polyester composite yarn, the cellulose natural staple yarn, and the polyamide yarn constituting the knitted fabric 6 are preferably twisted yarns in which filaments and fibers are twisted with each other. By bundling filaments and fibers in the yarn constituting the knitted fabric 6, the abrasion resistance is improved. Further, by twisting and collecting the filaments and fibers in the yarns constituting the knitted fabric 6, the knitted fabric can be easily knitted, and the filaments and fibers can be suppressed from fluffing, so that the appearance quality of the v-ribbed belt 1 can be improved.

In addition, knitted fabric 6 preferably does not contain polyurethane. By not including polyurethane having lower water absorbency and abrasion resistance than the fiber material in the knitted fabric 6, the water absorbency and abrasion resistance of the knitted fabric 6 can be prevented from being lowered. It is considered that the knitted fabric 6 is inferior in stretchability because it does not contain a polyurethane yarn or the like which is often used, but the knitted fabric 6 can secure stretchability because it contains a polyester composite yarn which is excellent in stretchability. The knitted fabric 6 may contain a polyester composite yarn, a cellulose natural spun yarn, a polyamide yarn, and a fiber having BR > O. The total content of the polyester composite yarn, the cellulose natural spun yarn, and the polyamide yarn in the knitted fabric 6 is preferably 80 mass% or more. The total content of the cellulosic natural spun yarn and the polyamide yarn in the layer on the friction transmission surface side of the knitted fabric 6 is preferably 70 mass% or more.

The thickness of the knitted fabric 6 woven in a multilayer structure including the bulky yarn is preferably 0.6mm or more. By setting the thickness of the knitted fabric 6 to 0.6mm or more, the rubber component of the compressed layer 4 can be suppressed from bleeding out to the friction transmitting surface side through the knitted fabric 6, and the difference between the friction coefficient in the dry state and the friction coefficient in the wet state of the friction transmitting surface can be reduced, and therefore, the water injection noise generation resistance can be improved. When the thickness of the knitted fabric 6 is 0.7mm or more, the rubber component of the compression layer 4 can be more reliably suppressed from bleeding out to the friction transmission surface side through the knitted fabric 6, and is particularly preferably 0.8mm or more.

The knitted fabric 6 may contain or have attached thereto a surfactant or a hydrophilic softening agent as a hydrophilization treatment agent. When the hydrophilization treatment agent is contained or attached to the knitted fabric 6 in this manner, if water droplets are attached to the frictional transmission surface (knitted fabric 6), the water droplets quickly wet and spread on the surface of the knitted fabric 6 after the hydrophilization treatment to form a water film, and further, the water is absorbed by the natural cellulosic spun yarns of the knitted fabric 6, and the water film on the frictional transmission surface disappears. Therefore, a decrease in the friction coefficient of the friction transmission surface in the wet state can be further suppressed.

As the hydrophilization treatment agent, a surfactant or a hydrophilic softening agent can be used. As a method for containing or attaching the hydrophilizing agent to the knitted fabric 6, a method of spraying the hydrophilizing agent to the knitted fabric 6, a method of coating the knitted fabric 6 with the hydrophilizing agent, or a method of immersing the knitted fabric 6 in the hydrophilizing agent can be employed. In the case where the hydrophilization agent is a surfactant, the following method may be employed in the production of the v-ribbed belt 1: the surface active agent is applied to the surface of a cylindrical outer mold having a plurality of rib molds engraved on the inner peripheral surface thereof, and vulcanization molding is performed, whereby the knitted fabric 6 contains the surface active agent. Among these methods, a method of immersing knitted fabric 6 in a hydrophilization treatment agent is preferable because the hydrophilization treatment agent can be contained and adhered easily and uniformly.

The surfactant is a generic term for a substance having a hydrophilic group easily compatible with water and a hydrophobic group easily compatible with oil (lipophilic group) in a molecule, and has the following effects in addition to the effect of uniformly mixing a polar substance and a nonpolar substance: reducing surface tension to improve wettability, or sandwiching a surfactant between substances to reduce interfacial friction.

The kind of the surfactant is not particularly limited, and an ionic surfactant, a nonionic surfactant, or the like can be used. The nonionic surfactant may be a polyethylene glycol type nonionic surfactant or a polyhydric alcohol type nonionic surfactant.

The polyethylene glycol type nonionic surfactant is a nonionic surfactant in which ethylene oxide is added to a hydrophobic base component having a hydrophobic group such as a higher alcohol, an alkylphenol, a higher fatty acid ester of a polyhydric alcohol, a higher fatty acid amide, or polypropylene glycol to give a hydrophilic group.

The knitted fabric 6 may be subjected to an adhesion treatment for the purpose of improving adhesion to the rubber composition constituting the compression layer 4 (the rubber composition forming the surface of the rib 2). Examples of the adhesion treatment of the knitted fabric 6 include an immersion treatment in a resin treatment liquid obtained by dissolving an epoxy compound or an isocyanate compound in an organic solvent (toluene, xylene, methyl ethyl ketone, or the like), an immersion treatment in a resorcinol-formaldehyde-latex (RFL liquid), and an immersion treatment in a rubber paste obtained by dissolving a rubber composition in an organic solvent. As other methods of the bonding treatment, for example, a rubbing treatment in which the knitted fabric 6 and the rubber composition are passed through a calender roll to roll the rubber composition into the knitted fabric 6, a coating treatment in which a rubber paste is applied to the knitted fabric 6, a coating treatment in which the rubber composition is laminated on the knitted fabric 6, or the like can be employed. By thus bonding the knitted fabric 6, the adhesiveness to the compressed layer 4 can be improved, and the knitted fabric 6 can be prevented from peeling off during the running of the v-ribbed belt 1. Further, by performing the bonding treatment, the wear resistance of the rib 2 can be improved.

Here, it is preferable that the rubber composition constituting the compression layer 4 is bonded to the knitted fabric 6 by the bonding treatment, so that the rubber composition does not bleed out on the friction transmission surface (the surface side in contact with the driving pulley 21 and the driven pulley 22) of the knitted fabric 6. When the rubber composition bleeds out from the knitted fabric 6 to the friction transmission surface side, the water absorption property is lowered, and therefore, the reduction of the friction coefficient in the wet state is increased, and the water injection noise generation resistance is lowered. Therefore, since sufficient water absorption can be ensured by eliminating the bleeding of the rubber composition to the friction transmission surface of the knitted fabric 6, the water injection noise generation resistance can be improved.

(method of manufacturing V-ribbed belt 1)

Hereinafter, a method for manufacturing the v-ribbed belt 1 will be described with reference to fig. 4. First, as shown in fig. 4(a), an unvulcanized sheet 3S for an extension layer is wound around a cylindrical inner mold 52 having a flexible jacket 51 attached to an outer peripheral surface thereof, a core wire 5 is spirally spun thereon, and an unvulcanized sheet 4S for a compression layer and a knitted fabric 6 are sequentially wound (covered) thereon to form a molded body 10. Then, the inner mold 52 around which the molded body 10 is wound is concentrically provided on the inner peripheral side of the outer mold 53 having a plurality of rib molds 53a engraved on the inner peripheral surface. At this time, a predetermined gap is provided between the inner peripheral surface of the outer mold 53 and the outer peripheral surface of the molded body 10.

Here, when the v-ribbed belt 1 is formed as described above, the knitted fabric 6 needs to be formed into a cylindrical shape so as to follow the outer periphery of the compression layer sheet 4S. Therefore, although there is a method of preparing an endless knitted seamless fabric using a circular knitting machine or the like, in this case, it is necessary to prepare a knitted seamless fabric corresponding to the length (circumferential length) of the v-ribbed belt 1. In this case, when a knitted fabric that is too long (having an excessively large circumferential length) with respect to the length of the v-ribbed belt 1 is used, the knitted fabric may be excessively large and overlap, which may cause quality abnormality, whereas when a knitted fabric that is too short (having an excessively small circumferential length) is used, it is expected that the shape of the rib 2 to be formed becomes poor, or the rubber composition of the compression layer sheet 4S bleeds out on the friction transmission surface, which may cause a reduction in the water injection noise generation resistance. Therefore, if the v-ribbed belt 1 of various lengths is to be manufactured, the same number of semi-finished products as the v-ribbed belt needs to be prepared, and waste is easily generated.

Therefore, in order to form the knitted fabric 6 into a cylindrical shape so as to follow the outer periphery of the sheet 4S for a compression layer, it is preferable to adopt a method of joining both ends of the knitted fabric 6 having a rectangular shape in accordance with the length of the v-ribbed belt 1 to produce the knitted fabric 6 having a cylindrical shape. In this case, the knitted fabric 6 having the optimum circumferential length can be prepared (adjusted) regardless of the length of the v-ribbed belt 1, and therefore, the quality is stable. Further, since the flat knitting machine can be used in addition to the circular knitting machine, the degree of freedom is high, and since one type of semi-finished product can be used, waste is avoided.

As a method of joining both ends of the knitted fabric 6, the following method can be exemplified: a method of cutting and welding a cut surface of a yarn constituting the knitted fabric 6 with a cutter heated to a temperature near the melting point thereof (thermal fusion, thermal welding), a method of cutting and welding with a cutter subjected to ultrasonic vibration while pressing (ultrasonic welding), sewing with a sewing machine, overlock sewing, butt jointing, and the like. The timing of joining the both ends of the knitted fabric 6 may be performed before the molding of the v-ribbed belt 1, or may be performed during the molding of the v-ribbed belt 1 (for example, the joining of the both ends of the knitted fabric 6 is performed on the compression layer sheet 4S wound around the inner mold 52). In the case of performing the forming of the v-ribbed belt 1 before, hot melting, ultrasonic welding, sewing by a sewing machine, and serging can be easily applied, and in the case of performing the forming of the v-ribbed belt 1, butt joint can be easily applied. Among them, ultrasonic welding and butt joining are preferable because the seam of the knitted fabric 6 has good appearance. The joining portion of the knitted fabric 6 may be 1 portion or a plurality of portions. From the viewpoint of reducing man-hours and improving appearance, the joining portion of the knitted fabric 6 is preferably 1 portion or 2 portions.

Next, as shown in fig. 4(b), the flexible jacket 51 is expanded toward the inner peripheral surface of the outer mold 53 at a predetermined expansion rate (for example, 1 to 6%), and the sheet for a compression layer 4S of the molded body 10 and the knitted fabric 6 are pressed into the rib mold 53a of the outer mold 53, and in this state, vulcanization treatment is performed (for example, at 160 ℃ for 30 minutes).

Finally, as shown in fig. 4(c), the inner mold 52 is pulled out from the outer mold 53, the vulcanized rubber sleeve 10A having the plurality of ribs 2 is released from the outer mold 53, and then the vulcanized rubber sleeve 10A is cut into a predetermined width in the circumferential direction by a cutter to be processed into the v-ribbed belt 1. The method for producing the v-ribbed belt 1 is not limited to the above method, and other known methods disclosed in, for example, japanese patent application laid-open No. 2004-82702 and the like may be used.

According to the v-ribbed belt 1, the knitted fabric 6 covering the friction transmission surface side contains the natural cellulosic spun yarn, so that the water absorption of the v-ribbed belt 1 can be improved, and the water injection noise generation resistance can be improved. Further, by incorporating the polyester composite yarn into the knitted fabric 6, the stretchability of the knitted fabric 6 can be improved, and the adaptability of the knitted fabric 6 to the V-shaped rib 2 when the V-shaped rib 2 is formed on the V-ribbed belt 1 by the mold (the inner mold 52 and the outer mold 53) can be improved. Further, by incorporating the polyamide-based yarn into the knitted fabric 6, abrasion resistance can be improved, and abrasion of the cellulose-based natural spun yarn can be suppressed, so that water injection noise generation resistance can be maintained for a long period of time.

Further, since the stretch ability is improved by weft knitting the knitted fabric 6 covering the friction transmission surface side of the V-ribbed belt 1, the rib 2 is less likely to have a defective shape in the manufacturing process of forming the V-shaped rib 2 on the V-ribbed belt 1 by the dies (the inner die 52 and the outer die 53). Further, by making the knitted fabric 6 have a multilayer structure, the rubber component of the compressed layer 4 can be suppressed from bleeding out to the friction transmission surface side through the knitted fabric 6, and the difference between the friction coefficient in the dry state and the friction coefficient in the wet state of the friction transmission surface can be reduced, so that the water injection noise resistance can be improved.

Further, by disposing the cellulose-based natural spun yarn having high water absorbability in the layer on the friction transmission surface side of the v-ribbed belt 1, water that has permeated between the driving pulley 21 and the driven pulley 22 and the v-ribbed belt 1 can be rapidly absorbed to stabilize the friction coefficient (suppress a decrease in the friction coefficient in a wet state), and therefore, the water injection noise resistance can be improved. Further, by disposing the polyamide-based yarn having high abrasion resistance in the layer on the friction transmission surface side, abrasion of the cellulose-based natural spun yarn can be suppressed, and water injection noise generation resistance can be maintained for a long period of time.