JP6949784B2 - V-ribbed belt and its manufacturing method - Google Patents

Description

The present invention relates to a V-ribbed belt and a method for manufacturing the same.

A V-ribbed belt is widely used as a belt for driving an auxiliary machine of an automobile. The V-ribbed belt has a V-shaped rib portion extending along the circumferential direction of the belt, and power transmission is performed by frictionally engaging the side surface of the rib portion with the side surface of the groove of the pulley. Conventionally, the mainstream of V-ribbed belts is one in which the rubber composition of the belt body is exposed.

However, in such a conventional product, the rib portion where the rubber is exposed tends to be worn due to friction with the pulley, and there is a problem in durability. Further, when the rubber is exposed, a slipping sound is generated when the belt slips with the pulley under a large fluctuation of the belt speed or a high load condition, and there is also a problem in sound resistance. In particular, when running in the rain, water enters the engine room, and if water adheres between the belt and the pulley, the friction coefficient of the belt decreases and slip noise may occur frequently.

For such a problem, a belt whose rib surface is coated with a knitted fabric is known. For example, in the V-ribbed belt disclosed in Patent Document 1, the surface of the rib portion is covered with a seamless tubular flat knitted fabric containing elastic yarn and cellulose-based fiber or yarn.

Patent No. 5337795

However, as shown in FIG. 3B, since the knitted fabric 100 is knitted while entwining the yarns in a loop shape, the knitted fabric 100 inevitably has a large gap between the yarns. Exists. The existence of this gap becomes a problem especially when the belt is manufactured by the molding method. In the molding method, the rib shape of the belt is formed by expanding the belt molded body made of the rubber composition to the outside and pressing it against the mold. At that time, when the knitted fabric 100 is adopted as the protective layer of the rib portion, the rubber composition easily penetrates through the gap between the yarns of the knitted fabric 100 and is exposed to the outside. As a result, on the friction transmission surface, the rubber composition is not covered with the thread and occupies a large proportion of the place where it comes into contact with the pulley, and the durability and sound resistance of the belt are not sufficient.

Therefore, an object of the present invention is to suppress the exposure of the rubber composition from the protective layer in the V-ribbed belt.

The V-ribbed belt of the present invention has a plurality of V-shaped rib portions extending in the longitudinal direction of the belt and arranged in the width direction of the belt, and the friction transmission surface of the rib portions is a combination of three or more braided yarns. It is composed of a braid formed from the above.

According to the above configuration, in the braid, since the plurality of braided yarns are densely arranged, the gap between the yarns is smaller than that of the knitted fabric. In the present invention, since the above-mentioned structure is adopted as the protective layer constituting the friction transmission surface, the exposure of the rubber composition from the protective layer can be suppressed.

In the V-ribbed belt of the present invention, the assembly is preferably a seamless cylindrical assembly.

According to the above configuration, since there is no seam (seam) in the braid, it is unlikely that the braid will crack from the joint and the braid will peel off from the interface between the compression layer and the protective layer.

In the V-ribbed belt of the present invention, it is preferable that the braid has a shaft yarn parallel to the axial direction of the braid, and the shaft yarn contains an elastic yarn.

When the shaft thread is arranged on the tubular braid, the shape of the braid is stable in the axial direction. Therefore, the belt can be easily handled in the manufacturing process. Further, since the shaft yarn contains elastic yarn, the elasticity of the braid is high. Therefore, the followability when the rubber composition is pressed against the mold is improved, and the rib portion can be formed with high accuracy.

In the V-ribbed belt of the present invention, it is preferable that the assembly contains eight or more shaft threads.

Further, in the V-ribbed belt of the present invention, it is preferable that the braid contains 30 or more braided yarns.

In the V-ribbed belt of the present invention, it is preferable that the shaft yarn contains a polyurethane elastic yarn as the elastic yarn.

In the V-ribbed belt of the present invention, it is preferable that the braided yarn contains a bulky processed yarn.

According to the above configuration, since the braided yarn contains a bulky processed yarn, the tubular braid has high elasticity in the peripheral length direction. Therefore, the handling workability in the belt manufacturing process is improved, and the followability when forming the rib portion is also excellent.

In the V-ribbed belt of the present invention, the braided yarn may include a nylon woolly processed yarn as the bulky processed yarn.

In the V-ribbed belt of the present invention, it is preferable that the braiding pitch, which is the distance between the center lines of the adjacent braided yarns, is 10 mm or less.

If the braid has a braid pitch of 10 mm or less, the gap between the braids is small and the rubber composition is less likely to be exposed on the friction transmission surface.

In the V-ribbed belt of the present invention, the total fineness of one braided yarn is preferably 500 dtex or more.

When the total fineness of the braided yarn is 500 dtex or more, the gap between the yarns is small and the rubber composition is not easily exposed to the friction transmission surface.

In the method for manufacturing a V-ribbed belt of the present invention, a braid is placed on the outside of a tubular belt molded body, the belt molded body is expanded outward, and the braid is sandwiched and pressed against a mold. A rib shape is formed on the belt molded body.

In the present invention, after arranging the braid on the outside of the tubular belt molded body, the belt molded body is expanded to the outside, and the outer surface of the belt molded body is pressed against the mold with the braid sandwiched between them. At this time, in a braid in which the braids are densely arranged, the gap between the yarns is small, so that the rubber composition constituting the belt molded body does not easily penetrate the braid. Therefore, a belt having a small amount of exposure of the rubber composition from the protective layer can be obtained.

In the method for manufacturing a V-ribbed belt of the present invention, it is preferable that the seamless tubular braid is formed by combining a braid and a shaft yarn on the outer circumference of a mandrel.

According to the above configuration, the tubular braids are combined on the outer circumference of the mandrel. As a result, the gap between the braided yarns becomes uniform in one tubular braid.

In the method for manufacturing a V-ribbed belt of the present invention, it is preferable that the outer peripheral length of the mandrel is longer than the outer peripheral length of the belt molded body.

After pulling the tubular assembly out of the mandrel, the tubular assembly shrinks. However, according to the above configuration, by forming the tubular assembly in advance so as to have a long peripheral length in anticipation of shrinkage, the work of covering the tubular assembly on the belt molded body is not difficult.

The exposure of the rubber composition from the protective layer in the V-ribbed belt can be suppressed.

It is the schematic perspective view explaining the example of the belt transmission device using the V-ribbed belt which concerns on this embodiment. FIG. 1 is a cross-sectional view taken along the line I-I of FIG. 1, which is a cross-sectional view taken along the line of a V-ribbed belt. (A) It is a figure which shows the braid used as a protective layer in this embodiment. (B) It is a figure which shows the knitting cloth of the comparison target of a braid. (A) It is a schematic diagram of the assembly machine of this embodiment. (B) It is a trajectory diagram of a spindle when assembling a braid with an assembling machine. It is a figure explaining the manufacturing method of the V ribbed belt.

(Belt transmission device 14)
Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 shows a belt transmission device 14 for driving an auxiliary machine using the V-ribbed belt 1 according to the present embodiment. The belt transmission device 14 has a drive pulley 15, a driven pulley 16, and an endless V-ribbed belt 1, and the V-ribbed belt 1 is wound around the drive pulley 15 and the driven pulley 16. The endless V-ribbed belt 1 is formed with a plurality of V-shaped rib portions 2 extending in the belt circumferential direction on the inner peripheral side. A plurality of V-shaped grooves 151 and 161 are formed on the outer peripheral surfaces of the drive pulley 15 and the driven pulley 16, and each rib portion 2 of the V-ribbed belt 1 is fitted into the plurality of V-shaped grooves 151 and 161. There is.

(Structure of V-ribbed belt 1)
As shown in FIG. 2, the V-ribbed belt 1 is composed of an stretch layer 4 forming the back surface of the belt on the outer peripheral side, a compression layer 3 provided on the inner peripheral side of the stretch layer 4, and the stretch layer 4 and the compression layer 3. It is provided with a core wire 5 embedded in the space and extending in the circumferential direction of the belt. The compression layer 3 is formed with a plurality of V-shaped ribs 22 extending in the belt circumferential direction and lining up in the belt width direction on the inner peripheral side of the compression layer 3. The surface of the rib 22 is covered with the protective layer 6, and the surface of the rib 22 is the interface 21 between the compression layer 3 and the protective layer 6. As will be described in detail later, the protective layer 6 is a braid 7. The ribs 22 and the protective layer 6 each extend in the longitudinal direction of the belt and form a plurality of V-shaped rib portions 2 arranged in the width direction of the belt. The surface of the rib portion 2 is a portion that comes into contact with the pulleys 15 and 16, and functions as a friction transmission surface 61 that transmits power between the V-ribbed belt 1 and the pulleys 15 and 16.

The compression layer 3 and the extension layer 4 are both formed of a rubber composition, as will be described later. An adhesive layer may be provided between the compression layer 3 and the extension layer 4 for the purpose of improving the adhesiveness of the core wire 5 to the compression layer 3 and the extension layer 4. 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 compression layer 3 or between the adhesive layer and the extension layer 4. good.

(Compression layer 3)
As the rubber component of the rubber composition forming the compression layer 3, vulverable or crosslinkable rubber, for example, diene rubber (natural rubber, isoprene rubber, butadiene rubber, chloroprene rubber, styrene butadiene rubber, acrylonitrile butadiene rubber, hydrogen Chemicald nitrile rubber, mixed polymer of hydride nitrile rubber and unsaturated carboxylic acid metal salt, etc.), ethylene-α-olefin elastomer, chlorosulphonized polyethylene rubber, alkylated chlorosulphonized polyethylene rubber, epichlorohydrin rubber, acrylic rubber, Examples include silicone rubber, urethane rubber, and fluororubber.

Of these, those in which an unvulcanized rubber layer is formed from a rubber composition containing sulfur or an organic peroxide and the unvulcanized rubber layer is vulcanized or crosslinked are preferable, and in particular, ozone resistance, heat resistance, and cold resistance are obtained. Ethylene-α-olefin elastomer (ethylene-α-olefin rubber) is preferable from the viewpoint of having properties and being excellent in economy. Examples of the ethylene-α-olefin elastomer include ethylene-α-olefin rubber (ethylene-propylene rubber) and ethylene-α-olefin-diene rubber (ethylene-propylene-diene copolymer). Examples of the α-olefin include propylene, butene, pentane, methylpentene, hexene, octene and the like. These α-olefins can be used alone or in combination of two or more. Examples of the diene monomer used as a raw material for these are non-conjugated diene-based monomers such as dicyclopentadiene, methylenenorbornene, ethylidenenorbornene, 1,4-hexadiene, and cyclooctadiene. These diene monomers can be used alone or in combination of two or more.

In the ethylene-α-olefin elastomer, the ratio of ethylene to α-olefin (mass ratio of the former / the latter) is 40/60 to 90/10, preferably 45/55 to 85/15, and more preferably 55/45. A range of ~ 80/20 is good. The proportion of diene can be selected from the range of 4 to 15% by mass, and is preferably in the range of, for example, 4.2 to 13% by mass, preferably 4.4 to 11.5% by mass. The iodine value of the ethylene-α-olefin elastomer containing a diene component may be, for example, in the range of 3 to 40, preferably 5 to 30, and more preferably 10 to 20. If the iodine value is too small, the vulcanization of the rubber composition becomes insufficient and wear and adhesion are likely to occur. If the iodine value is too large, the scorch of the rubber composition becomes short and difficult to handle, and the heat resistance becomes high. Tends to decline.

Examples of the organic peroxide forming the unsulfided rubber layer include diacyl peroxide, peroxy ester, and dialkyl peroxide (dicumyl peroxide, t-butylcumyl peroxide, 1,1-di-butylperoxy-3). , 3,5-trimethylcyclohexane, 2,5-dimethyl-2,5-di (t-butylperoxy) -hexane, 1,3-bis (t-butylperoxy-isopropyl) benzene, di-t-butyl Peroxide, etc.) and the like. These organic peroxides can be used alone or in combination of two or more. Further, the organic peroxide preferably has a temperature range of 150 ° C. to 250 ° C., preferably about 175 ° C. to 225 ° C., which has a half-life of 1 minute due to thermal decomposition.

The ratio of the vulcanizing agent or cross-linking agent (particularly organic peroxide) in the unvulcanized rubber layer is 1 to 10 parts by mass in terms of solid content with respect to 100 parts by mass of the rubber component (ethylene-α-olefin elastomer, etc.). It is preferably 1.2 to 8 parts by mass, and more preferably 1.5 to 6 parts by mass.

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

Further, the rubber composition may further contain a co-crosslinking agent (crosslinking aid or co-vulcanizing agent) in order to increase the degree of cross-linking and prevent adhesive wear and the like. Common cross-linking agents include conventional cross-linking aids, such as polyfunctional (iso) cyanurates (triallyl isocyanurate, triallyl cyanurate, etc.), polydiene (1,2-polybutadiene, etc.), and metal salts of unsaturated carboxylic acids. (Zinc (meth) acrylate, magnesium (meth) acrylate, etc.), oximes (quinonedioxime, etc.), guanidines (diphenylguanidine, etc.), polyfunctional (meth) acrylate (ethylene glycol di (meth) acrylate, butane) Didiole (meth) acrylate, trimethylpropantri (meth) acrylate, etc.), bismaleimides (N, N'-m-phenylene bismaleimide, etc.) and the like can be mentioned. These cross-linking aids can be used alone or in combination of two or more. The ratio of the cross-linking aid (total amount when a plurality of types are combined) is 0.01 to 10 parts by mass, preferably 0.05 to 8 parts by mass with respect to 100 parts by mass of the rubber component in terms of solid content. good.

In addition, the rubber composition may contain short fibers, if necessary. As short fibers, cellulose-based fibers (cotton, rayon, etc.), polyester-based fibers (PET, PEN fibers, etc.), aliphatic polyamide fibers (6 nylon fibers, 66 nylon fibers, 46 nylon fibers, etc.), aromatic polyamide fibers (46 nylon fibers, etc.), aromatic polyamide fibers (6 nylon fibers, 66 nylon fibers, 46 nylon fibers, etc.) (P-aramid fiber, m-aramid fiber, etc.), vinylon fiber, polyparaphenylene benzobisoxazole (PBO) fiber, etc. can be mentioned. These short fibers may be subjected to a conventional adhesive treatment or surface treatment, for example, a treatment with an RFL liquid or the like, in order to enhance the dispersibility and adhesiveness in the rubber composition. The ratio of the short fibers is preferably 1 to 50 parts by mass, preferably 5 to 40 parts by mass, and more preferably 10 to 35 parts by mass with respect to 100 parts by mass of the rubber component.

In addition, the rubber composition may optionally include conventional additives such as vulture aids, smelting retardants, reinforcing agents (carbon black, silicon oxide such as hydrous silica), fillers (clay, carbonic acid, etc.). Calcium, talc, mica, etc.), metal oxides (zinc oxide, magnesium oxide, calcium oxide, barium oxide, iron oxide, copper oxide, titanium oxide, aluminum oxide, etc.), plasticizers (paraffin oil, naphthenic oil, process) Oils such as oils), processing agents or processing aids (stearic acid, metal stearate, wax, paraffin, fatty acid amide, etc.), anti-aging agents (antioxidants, thermal anti-aging agents, bending crack inhibitors, etc.) Ozone deterioration inhibitor, etc.), colorant, tackifier, coupling agent (silane coupling agent, etc.), stabilizer (ultraviolet absorber, antioxidant, ozone deterioration inhibitor, heat stabilizer, etc.), lubricant ( It may contain graphite, molybdenum disulfide, ultra-high molecular weight polyethylene, etc.), flame retardant, antistatic agent, and the like. The metal oxide may act as a cross-linking agent. These additives can be used alone or in combination of two or more. The ratio of these additives can be selected from the conventional range according to the type. For example, the ratio of the reinforcing agent (carbon black, silica, etc.) is 10 to 200 parts by mass (carbon black, silica, etc.) with respect to 100 parts by mass of the rubber component. 20 to 150 parts by mass, preferably 1 to 15 parts by mass (preferably 2 to 10 parts by mass) of metal oxide (zinc oxide, etc.), and 1 to 1 to 15 parts by mass of plasticizer (oils such as paraffin oil). The ratio of 30 parts by mass (preferably 5 to 25 parts by mass) and the processing agent (stearic acid or the like) is preferably 0.1 to 5 parts by mass (preferably 0.5 to 3 parts by mass).

(Extended layer 4)
The stretch layer 4 is formed of the same rubber composition as the compression layer 3. As the rubber component of this rubber composition, the same type or type of rubber as the rubber component of the compression layer 3 is used. Further, the proportions of additives such as a vulcanizing agent or a cross-linking agent, a co-cross-linking agent, and a vulcanization accelerator can also be selected from the same range as the rubber composition of the compression layer 3, respectively.

The rubber composition of the stretch layer 4 may contain short fibers similar to those of the compression layer 3 in order to suppress the generation of abnormal noise due to the adhesion of the rubber composition of the stretch layer 4 when the back surface is driven. The form of the short fiber may be linear or partially bent (for example, the milled fiber described in JP-A-2007-120507). When the V-ribbed belt 1 is running, cracks may occur in the stretch layer 4 in the belt circumferential direction, and the V-ribbed belt 1 may be broken. However, this is prevented by orienting the short fibers in the belt width direction or the random direction. be able to. Further, in order to suppress the generation of abnormal noise when driving the back surface, an uneven pattern may be provided on the surface (back surface of the belt) of the stretch layer 4. Examples of the uneven pattern include a knitted fabric pattern, a woven fabric pattern, a blind woven fabric pattern, an embossed pattern (for example, a dimple shape), and the size and depth are not particularly limited.

The stretch layer 4 may be formed of a cloth (reinforcing cloth) such as canvas. Examples of the reinforcing cloth include woven cloth, wide-angle canvas, knitted cloth, and non-woven fabric. Of these, woven fabrics woven in the form of plain weave, twill weave, satin weave, etc., and wide-angle canvas and knitted fabrics in which the crossing angle between the warp and weft is about 90 ° to 130 ° are preferable. As the fibers constituting the reinforcing cloth, fibers similar to the short fibers can be used. The reinforcing cloth may be treated with an RFL liquid (immersion treatment or the like) and then subjected to a coating treatment or the like to form a canvas with rubber.

(Core line 5)
The core wire 5 is not particularly limited, and polyester fiber (polybutylene terephthalate fiber, polyethylene terephthalate fiber, polytrimethylene terephthalate fiber, polyethylene naphthalate fiber, etc.), aliphatic polyamide (nylon) fiber (6 nylon fiber, 66 nylon). Fibers, 46 nylon fibers, etc.), aromatic polyamide (aramid) fibers (copolyparaphenylene, 3,4'oxydiphenylene, terephthalamide fibers, poly-p-phenylene terephthalamide fibers, etc.), polyallylate fibers, glass fibers, A cord formed of carbon fiber, PBO fiber, or the like can be used. These fibers can be used alone or in combination of two or more. Further, these fibers are appropriately selected according to the expansion rate of the flexible jacket 181 described later. For example, in the case of high elongation such that the expansion rate exceeds 2%, polyester fibers having a low elasticity (particularly low elasticity polybutylene terephthalate fiber) and nylon fibers (particularly 66 nylon fibers and 46 nylon fibers) are preferable. This is because with fibers having a high elastic modulus such as aramid fibers and PBO fibers, the fibers cannot be sufficiently stretched even if the flexible jacket 181 expands, and the pitch of the core wires 5 embedded in the V-ribbed belt 1 This is because the line is not stable and the proper shape of the rib portion 2 is not formed. Therefore, in order to use a fiber having a high elastic modulus, it is preferable to set the expansion rate of the flexible jacket 181 to a low value (for example, about 1%).

(Protective layer 6)
As mentioned earlier, as shown in FIG. 2, the surface of the rib portion 2 of the V-ribbed belt 1 of the present embodiment, that is, the friction transmission surface 61 of the belt is composed of the protective layer 6. As a result, wear of the interface 21 between the compression layer 3 and the protective layer 6 is suppressed, and durability is improved. Further, since the exposure of the rubber composition to the friction transmission surface 61 is suppressed, improvement in sound resistance can be expected.

(Assembly 7)
By the way, in the present embodiment, the braid 7 is particularly used as the protective layer 6 constituting the friction transmission surface 61. A braid is a cloth made by combining three or more braided yarns, and has a fiber structure significantly different from that of a knitted fabric 100 knitted while entwining the yarns in a loop or a woven fabric in which warp yarns and weft yarns are woven at right angles. Two features of the braid are high elasticity and high thread density. First, the braid has much greater elasticity than the woven fabric woven with warp and weft due to the fiber structure of the braid. On the other hand, the elasticity of the knitted fabric 100 is as large as the elasticity of the braid. However, the braid is decisively different from the knitted fabric 100 in that the braided yarns are densely arranged. As shown in FIG. 3B, the knitted fabric 100 inevitably has a large gap between the yarns due to the feature that the yarns are knitted while being entwined in a loop shape. On the other hand, as shown in FIG. 3A, since the yarns are densely arranged in the braid, the gap between the yarns is smaller than that of the knitted fabric 100.

Further, the braid 7 used in the present embodiment is a seamless tubular braid 7 having no seams and excellent strength. Since there is no seam in the braid 7, the braid 7 may crack from the seam and the protective layer 6 (braid 7) may peel off from the interface 21 between the compression layer 3 and the protective layer 6. Hard to get up. The braid can be formed only by a plurality of braided yarns, but in the present embodiment, from the viewpoint of improving the shape retention of the tubular braid 7 and improving the handleability in the belt manufacturing process described later. , Axoneme 72 parallel to the axial direction of the tubular assembly 7 is used. That is, the braid 7 of the present embodiment is formed by combining three or more braids 71 and a shaft yarn 72 with each other. The braided yarns 71 intersect with each other with a predetermined braided angle θ with respect to the axial direction of the braided yarn 7.

(Knitting yarn 71)
Originally, due to its fiber structure, the braid 7 has yarns arranged more densely than the knitted fabric. However, in order to enhance the effect of protecting the interface 21 between the compression layer 3 and the protective layer 6, the yarns are used. It is desirable that the intervals between the two are as small as possible. For example, the number of braided yarns 71 forming the braided fabric 7 is 30 or more. Further, it is preferable that the set pitch d, which is the distance between the center lines of the adjacent braids 71, is 10 mm or less. From the viewpoint of increasing the elasticity of the braid 7, a stretchable yarn is used for the braid 71. For example, as the braided yarn 71, a bulky processed yarn can be adopted. For example, nylon woolly processed yarn can be adopted as the bulky processed yarn. The total fineness of one braided yarn 71 is 500 dtex or more.

(Axoneme 72)
From the viewpoint of ensuring shape retention, it is preferable that a certain number of shaft threads 72 are arranged in the circumferential direction. For example, it is preferable that eight or more shaft threads 72 are included. In consideration of belt production by the molding method described later, in this embodiment, elastic yarn having good elasticity is adopted as the shaft yarn 72. As the elastic yarn, polyurethane elastic yarn can be adopted. As the polyurethane elastic yarn, for example, spandex (registered trademark) or leuka (registered trademark) can be used.

Alternatively, as the shaft yarn 72, a bulky processed yarn (processed yarn having a large cross-sectional bulk) which is an elastic yarn may be adopted. As the bulky processed yarn, for example, a woolly processed yarn, a Taslan processed yarn, a conjugate yarn, and a covering yarn can be adopted.

The woolly processed yarn is a yarn having elasticity from the structural aspect. For example, as the woolly processed yarn, a yarn having crimp obtained by temporarily twisting a fiber, heat-fixing it, and untwisting the fiber is used. You may.

The conjugated yarn has a cross-sectional structure in which two or more types of polymers having different heat shrinkage rates are bonded together in the fiber axis direction, and when heat is applied during manufacturing or processing, the shrinkage rate (heat shrinkage rate) of each polymer is different. As a result, crimping occurs and the yarn becomes bulky. For example, a composite yarn (PTT / PET conjugated yarn) in which polytrimethylene terephthalate (PTT) and polyethylene terephthalate (PET) are conjugated, or a composite yarn in which polybutylene terephthalate (PBT) and polyethylene terephthalate (PET) are conjugated (PTT). There is PBT / PET conjugate thread). As described above, conjugated yarns containing polyethylene terephthalate (PET) can be used.

Further, the covering yarn is a yarn in which the bulk of the cross section of the entire yarn is increased by covering (covering) the periphery of the core yarn with another yarn. For example, a composite yarn (PET / PU covering yarn) in which a polyurethane (PU) yarn having excellent elasticity is used as a core and polyethylene terephthalate (PET) is covered on the surface thereof, or a composite yarn in which a PU is used as a core and polyamide (PA) is covered. There is a thread (PA / PU covering thread). Among these composite yarns, PTT / PET conjugated yarns or PET / PU covering yarns, which are excellent in elasticity and abrasion resistance, are preferable.

Regarding the material of the bulky processed yarn, for example, water-absorbent fiber (for example, cellulose-based fiber), polyamide fiber (for example, nylon fiber or aramid fiber), polyester fiber (for example, polyethylene terephthalate fiber or polybutylene terephthalate fiber), polyurethane elastic. Bulky processed yarns made of materials such as fibers containing yarns can be used. The cellulose-based fibers include bamboo fiber, sugar cane fiber, seed hair fiber (cotton fiber (cotton linter), capoc, etc.), ginseng fiber (for example, hemp, kozo, honey mata, etc.), leaf fiber (for example, Manila hemp, New Zealand). Examples include natural plant-derived cellulose fibers (pulp fibers) such as hemp), animal-derived cellulose fibers such as wool, silk, and squirrel cellulose, bacterial cellulose fibers, and algae cellulose. Of these, cotton fibers are particularly preferable because they are excellent in water absorption.

The braid 7 can be subjected to an adhesive treatment for the purpose of improving the adhesiveness between the compression layer 3 and the interface 21 formed of the rubber composition. Such an adhesive treatment of the assembly 7 includes a dipping treatment in a resin-based treatment liquid in which an epoxy compound or an isocyanate compound is dissolved in an organic solvent (toluene, xylene, methyl ethyl ketone, etc.), and a resorcin-formaline-latex liquid (RFL liquid). ), And a rubber paste in which the rubber composition is dissolved in an organic solvent. Other methods of bonding treatment include, for example, a friction treatment in which the braid 7 and the rubber composition are passed through a calendar roll to imprint the rubber composition on the braid 7, and a spreading treatment in which the rubber glue is applied to the braid 7. A coating treatment or the like in which the rubber composition is laminated on the braid 7 can also be adopted.

By applying the adhesive treatment to the braid 7 in this way, the adhesiveness between the protective layer 6 (braid 7) and the compression layer 3 is improved, and the protective layer 6 (braid 7) during traveling of the V-ribbed belt 1 is improved. Can be prevented from peeling off. Further, the wear resistance of the rib portion 2 can be improved by performing the adhesive treatment. By adhering the rubber composition constituting the compression layer 3 to the protective layer 6 (composition 7) by the above-mentioned adhesive treatment, the rubber composition of the compression layer 3 is less likely to be exposed from the protective layer 6.

As shown in FIG. 4A, the braid 7 is manufactured using the braid 8. The shaft thread 72 is supplied from the lower part of the braiding machine 8 through the fixed cylinder 10, and the braiding thread 71 is wound around the spindle 11. A cylindrical mandrel 9 is installed at the center of the braiding machine 8, and the braided yarn 71 and the shaft yarn 72 are combined to form the braided yarn 7 on the outer circumference of the upper part of the mandrel 9. As shown in FIG. 4B, when the spindle 11 moves along the track 12, the braided yarn 71 and the shaft yarn 72 are combined, and the braided yarn 7 is formed on the upper part of the mandrel 9, and the braided yarn 7 is formed. Is wound by the winding device 13. The outer peripheral length of the mandrel 9 is longer than the outer peripheral length of the cylindrical belt molded body 17, which will be described later.

In the method for producing the braid 7 described above, the braid 71 and the shaft yarn 72 are combined with each other on the outer circumference of the mandrel 9. As a result, the gap between the braided yarn 71 and the braided yarn 71 becomes uniform in one tubular braid.

Further, the tubular assembly 7 contracts after the tubular assembly 7 is pulled out from the mandrel 9, but the tubular assembly 7 is formed so as to have a long circumference in advance in anticipation of the contraction. The work of covering the object 7 on the belt molded body 17 is not difficult.

(Manufacturing method of V-ribbed belt 1)
Hereinafter, a method for manufacturing the V-ribbed belt 1 will be described based on FIGS. 5A to 5C. The belt manufacturing process by a general molding method will be described as an example. First, as shown in FIG. 5A, an unvulcanized extension layer sheet 4S is wound around an inner mold 18 having a flexible jacket 181 attached to the outer peripheral surface of the mold, and a core wire 5 is placed on the inner mold 18 Is spirally spun, and the unvulcanized compression layer sheet 3S is sequentially wound therein to prepare a belt molded body 17. After that, the belt molded body 17 is covered with the tubular assembly 7 so that the axial direction thereof coincides with the axial direction of the inner mold 18, and the assembly 7 is arranged on the outside of the tubular belt molded body 17. After that, the inner mold 18 around which the braid 7 and the belt molded body 17 are wound is concentrically set on the inner peripheral side of the outer mold 19 of the mold in which a plurality of rib molds 19a are engraved on the inner peripheral surface. do. At this time, a predetermined gap is provided between the inner peripheral surface of the outer mold 19 and the outer peripheral surface of the belt molded body 17.

Subsequently, as shown in FIG. 5B, the flexible jacket 181 is expanded outward, that is, toward the inner peripheral surface of the outer mold 19 at a predetermined expansion rate (for example, 1 to 6%). The belt molded body 17 is pressed against the mold with the braid 7 sandwiched between them. As a result, the compression layer sheet 3S of the belt molded body 17 and the assembly 7 are press-fitted into the rib mold 19a of the outer mold 19 to form a rib shape on the belt molded body 17. In that state, a vulcanization treatment (for example, 160 ° C., 30 minutes) is performed.

Finally, as shown in FIG. 5C, the inner mold 18 is removed from the outer mold 19, the vulcanized rubber sleeve 17A having the plurality of rib portions 2 is removed from the outer mold 19, and then added using a cutter. The vulcanized rubber sleeve 17A is cut into a predetermined width in parallel with the circumferential length direction to finish the V-ribbed belt 1. The method for producing the V-ribbed belt 1 is not limited to the above method, and for example, other known methods disclosed in Japanese Patent Application Laid-Open No. 2004-82702 can be adopted.

(effect)
In the above molding method, when the belt molded body 17 is pressed against the rib mold 19a of the outer mold 19, if the elasticity of the protective layer 6 is small, the press-fitting of the belt molded body 17 into the rib mold 19a is hindered. The rib shape is not formed properly. Therefore, the protective layer 6 forming the friction transmission surface 61, which is the surface of the rib portion 2, needs to be elastic. Since the protective layer 6 needs to be elastic, the highly elastic braid 7 is suitable for the protective layer 6.

In the above molding method, in particular, since the axial direction of the tubular assembly 7 coincides with the width direction of the V-ribbed belt 1, the rubber composition flows into the rib mold 19a engraved on the outer mold 19, but the cylinder The shape structure 7 needs to follow, and the cylindrical structure 7 needs to have good elasticity in the axial direction thereof. Therefore, as the shaft thread 72, a polyurethane elastic thread, which is an elastic thread having good elasticity, can be adopted. In order to extend the flexible jacket 181 toward the inner peripheral surface of the outer mold 19 so that the tubular assembly 7 is along the inner peripheral surface of the outer mold 19, the tubular assembly 7 is oriented in the peripheral length direction thereof. Must also have elasticity. However, the elastic structure required in the circumferential length direction of the tubular assembly 7 is smaller than the elasticity required in the axial direction thereof. As the braided yarn 71, a nylon woolly processed yarn, which is a bulky processed yarn, can be adopted.

When a cloth having a structure having a large gap such as a knitted cloth is used as the protective layer 6, the rubber composition of the belt molded body 17 permeates between the threads of the protective layer 6 during vulcanization and is exposed. In this respect, the braid 7 in which the braid 71 is densely arranged is suitable for the protective layer 6. Further, it is preferable to reduce the yarn spacing by devising the braiding pitch d, the number of braided yarns 71, and the total fineness of the braided yarns 71.

When the braid is composed of only the braided yarn 71, the shape-retaining property of the tubular braid is low, and it becomes difficult to cover the belt molded body 17 in the belt manufacturing process, resulting in poor handleability. Therefore, it is preferable that the braid has a shaft thread 72.

(Example)
Next, the cylindrical assembly 7 according to the V-ribbed belt 1 of Examples 1 to 4 was produced using a 64-stroke 2-step type round assembly machine. The mandrel 9 had a diameter of 200 mm and an outer peripheral length of 628 mm. After the tubular assembly 7, the V-ribbed belt 1 having three rib portions 2 and a peripheral length of 600 mm was manufactured by the same manufacturing method as the V-ribbed belt 1 of the embodiment.

Here, the materials of the braided yarn 71 and the shaft yarn 72 constituting the braided fabric 7 according to the V-ribbed belt 1 of Examples 1 to 4 are listed below. Woolly processed yarn (FORMOSA CHEMICALS & FIBRE CORPORATION nylon 6 woolly processed yarn), nylon raw yarn (fiber bundle of nylon 66 manufactured by Asahi Kasei Corporation), polyurethane elastic yarn (Leuka manufactured by Asahi Kasei Corporation).

For the braids 7 according to Examples 1 to 4, the configurations of the braided yarn 71 and the shaft yarn 72 constituting each braided yarn 7 are shown in Table 1 below. In the braid 7 according to the first embodiment, as the braid 71, five 44 dtex fiber bundles were collected, and four further collected Woolly processed yarns having a total fineness of 880 dtex were used. Further, in the braid 7 according to the first embodiment, a polyurethane elastic yarn having a total fineness of 470 dtex was used as the shaft yarn 72. In the braid 7 according to the second embodiment, the same yarn as in the first embodiment was used as the braided yarn 71. Further, in the braid 7 according to the second embodiment, a composite yarn (PA / PU covering yarn) covered with a nylon raw yarn having a fineness of 125 dtex with a polyurethane elastic yarn having a fineness of 150 dtex as a core was used as the shaft yarn 72. In the braid 7 according to the third embodiment, the same yarn as in the first embodiment was used as the braided yarn 71. Further, in the braid 7 according to the third embodiment, a woolly processed yarn having a total fineness of 220 dtex, which is a collection of five 44 dtex fiber bundles, was used as the shaft yarn 72. In the braid 7 according to the fourth embodiment, a nylon raw yarn having a total fineness of 940 dtex was used as the braid 71. Further, in the braid 7 according to the fourth embodiment, the same thread as that of the first embodiment was used as the shaft thread 72.

(Table 1)

Table 1 above shows the evaluation results of the workability at the time of producing the V-ribbed belt 1 of Examples 1 to 4, the rib shape of the produced V-ribbed belt 1, and the exposure amount of the rubber composition from the protective layer 6. .. In Table 1, ◯ is good, ⊚ is particularly good, and Δ is a result that is not a problem in practical use but slightly inferior. The V-ribbed belts 1 of Examples 1 to 4 were produced using the braided yarn 71 of the braided fabric 7 and the braided yarn 7 produced by changing the yarn type and the number of the shaft yarns 72, respectively. In each of the examples, there was no problem in the workability at the time of producing the V-ribbed belt 1, the rib shape of the produced V-ribbed belt 1, and the amount of exposure of the rubber composition from the protective layer 6.

(Modification example)
Although the preferred embodiment of the present invention has been described above, the above embodiment can be modified and implemented as follows.

(1) A V-ribbed belt may be manufactured by using a tubular assembly that does not include a shaft thread that is parallel to the axial direction.

(2) In the belt manufacturing process, a tubular braid is produced by directly combining the braided yarn and the shaft yarn on the outer periphery of the belt molded body so that the tubular braid is covered with the belt molded body. May be good. By manufacturing the V-ribbed belt by this belt manufacturing method, there is no step of covering the belt molded body with the tubular braid, so even if a tubular braid having low shape retention is used, there is no problem in manufacturing the V-ribbed belt. Does not occur.

(3) A tubular assembly may be produced by connecting flat braids assembled in a flat shape, and a V-ribbed belt may be produced using the tubular assembly.

1 V-ribbed belt 2 Rib 21 Interface between compression layer and protective layer 22 Rib 3 Compression layer 4 Stretch layer 5 Core wire 6 Protective layer 61 Friction transmission surface 7 Braid 71 Braid 72 Axoneme 8 Braid 14 Belt transmission device 17 Belt molded body 18 Inner mold 19 Outer mold

Claims (13)

Each has a plurality of V-shaped rib portions extending in the longitudinal direction of the belt and lining up in the width direction of the belt.
A V-ribbed belt characterized in that the friction transmission surface of the rib portion is composed of a braid formed by combining three or more braided yarns. The V-ribbed belt according to claim 1, wherein the assembly is a seamless cylindrical assembly. The braid has an axoneme parallel to the axial direction of the braid.
The V-ribbed belt according to claim 2, wherein the shaft yarn includes an elastic yarn. The V-ribbed belt according to claim 3 , wherein the assembly includes eight or more shaft threads. The V-ribbed belt according to any one of claims 2 to 4, wherein the braid contains 30 or more braided yarns. The V-ribbed belt according to claim 3 or 4, wherein the shaft yarn contains a polyurethane elastic yarn as the elastic yarn. The V-ribbed belt according to any one of claims 1 to 6, wherein the braided yarn includes a bulky processed yarn. The V-ribbed belt according to claim 7, wherein the braided yarn includes a nylon woolly processed yarn as the bulky processed yarn. The V-ribbed belt according to any one of claims 1 to 8, wherein the braiding pitch, which is the distance between the center lines of the adjacent braided yarns, is 10 mm or less. The V-ribbed belt according to any one of claims 1 to 9, wherein the total fineness of one braided yarn is 500 dtex or more. The method for manufacturing a V-ribbed belt according to any one of claims 1 to 10.
Place the braid on the outside of the tubular belt molding,
A method for manufacturing a V-ribbed belt, which comprises expanding the belt molded body outward and pressing the braid against a mold to form a rib shape on the belt molded body. The assembly is a seamless tubular assembly.
The method for manufacturing a V-ribbed belt according to claim 11, wherein the seamless tubular braid is formed by combining a braided yarn and an axoneme on the outer circumference of a mandrel. The method for manufacturing a V-ribbed belt according to claim 12, wherein the outer peripheral length of the mandrel is longer than the outer peripheral length of the belt molded body.

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