V-shaped V-ribbed belt and manufacturing method thereof
阅读说明：本技术 V型多楔带及其制造方法 (V-shaped V-ribbed belt and manufacturing method thereof ) 是由 横山和贵 武市博树 长谷川新 西山健 光富学 于 2018-06-15 设计创作，主要内容包括：本发明提供一种V型多楔带,包括将4cN/dtex载荷时的中间伸长率为0.8％以上且拉伸弹性率为50～100GPa的高伸长率芳纶纤维与拉伸弹性率比该高伸长率芳纶纤维低的低模量纤维混捻而成的捻绳。(The invention provides a V-shaped V-ribbed belt, which comprises a twisted rope formed by mixing and twisting high-elongation aramid fibers with the middle elongation of more than 0.8% and the tensile elasticity of 50-100 GPa and low-modulus fibers with the tensile elasticity lower than that of the high-elongation aramid fibers at the load of 4 cN/dtex.)
1. A V-ribbed belt comprising a twisted rope obtained by twisting a high-elongation aramid fiber having an intermediate elongation of 0.8% or more and a tensile elasticity of 50-100 GPa at a load of 4cN/dtex with a low-modulus fiber having a tensile elasticity lower than that of the high-elongation aramid fiber.
2. The V-ribbed belt of claim 1 wherein,
the low-modulus fiber has a tensile modulus of 20GPa or less.
3. The V-ribbed belt according to claim 1 or 2,
the proportion of the aramid fiber with high elongation is 60-95% by mass in the twisted rope.
4. The V-ribbed belt according to any one of claims 1 to 3,
the twisted rope is formed by twisting a plurality of lower twisted threads or a plurality of untwisted threads, and the lower twist coefficient of the twisted rope is 0-6 and the upper twist coefficient of the twisted rope is 2-6.
5. The V-ribbed belt according to any one of claims 1 to 4,
the twisting rope is twisted in the same direction.
6. The V-ribbed belt of claim 5 wherein,
the ratio of the upper twist coefficient to the lower twist coefficient of the aramid fiber having a high elongation is 4 to 8.
7. The V-ribbed belt according to claim 5 or 6,
the ratio of the upper twist coefficient to the lower twist coefficient of the aramid fiber having a high elongation is 5 to 7.
8. The V-ribbed belt according to any one of claims 5-7,
the low twist coefficient of the high-elongation aramid fiber is 1 or less.
9. The V-ribbed belt according to any one of claims 1 to 4,
the twisted rope is twisted, and the lower twist coefficient of the high-elongation aramid fiber is more than 2.
10. The V-ribbed belt according to any one of claims 1 to 9,
at least a part of the friction transmission surface is covered with a fabric.
11. The V-ribbed belt according to any one of claims 1-10,
the V-ribbed belt is mounted on an engine mounted with a belt ISG drive.
12. A method for manufacturing the V-ribbed belt according to any one of claims 1 to 11, comprising a core wire preparation step of preparing a core wire by bonding the twisted cord,
in the core wire preparing step, thermal drawing is performed at a heat-set elongation of 3% or less at the time of heat treatment of the bonding treatment.
Technical Field
The present invention relates to a V-ribbed belt including a twisted cord formed by twisting aramid fibers and low modulus fibers as core fibers, and a method for manufacturing the V-ribbed belt.
Background
Recently, in the progress of strengthening the fuel economy restriction of automobiles, vehicles equipped with an idle stop mechanism have been increasing as one of measures for improving fuel economy of engines. In addition, in the engine restart from the idle stop state, a belt type ISG (Integrated Starter Generator) drive is widely used in which a crankshaft is driven from an alternator via an auxiliary machinery drive belt. In the belt type ISG drive, a higher dynamic tension is generated in the belt than in a normal engine not equipped with an ISG. For example, when the dynamic tension generated in the belt is about 250N/rib when the ISG is not mounted, the dynamic tension of about 350N/rib is generated in the belt when the belt type ISG drive is mounted. Therefore, the V-ribbed belt for driving an auxiliary machine used in an engine equipped with a belt-type ISG drive is required to have a high tensile modulus so as to keep the elongation of the belt small even when a high dynamic tension is generated. For this reason, it is preferable to use a core wire including a fiber having a small elongation and a high elastic modulus, such as an aramid fiber. Further, since the dynamic tension is high, a very high level of sound emission resistance and durability is required, and a structure in which the rib surface (friction transmission surface) is covered with a fabric is preferably used.
V-ribbed belts with rib surfaces covered with fabric are generally produced by a die-bonding method. However, in the die-bonding method, it is necessary to expand the laminated body of the constituent materials of the belt including the core wire in the outer circumferential direction, and therefore it is difficult to apply the core wire having a small elongation. When the elongation of the core wires is small, the laminate cannot be sufficiently expanded, the rib shape becomes poor, the pitch of the core wires (arrangement in the belt width direction of the core wires) becomes irregular, or the core wires are damaged, which causes a problem that the tensile strength and durability of the transmission belt are reduced. As a countermeasure against this problem, japanese patent application laid-open No. 2008-100365 (patent document 1) discloses a method for manufacturing a transmission belt using a twisted cord in which aramid fibers and fibers having a relatively large intermediate elongation are twisted together. This document describes that a high modulus transmission belt that can be used even in a drive device having a large load variation of an engine while suppressing occurrence of a defect in the pitch of the core wires and occurrence of core wire damage in press molding in a die-molding method and also in a mold-attaching method can be manufactured by twisting a fiber having a relatively large intermediate elongation such as a polyester fiber or a polyamide fiber with a rigid aramid fiber.
However, in this transmission belt, the elongation of the twisted cord during belt production and the durability of the belt may be insufficient, and improvement is desired.
Prior art documents
Patent document
Patent document 1: japanese patent laid-open No. 2008-100365 (claim 1, paragraph [0017] [0027 ])
Disclosure of Invention
Problems to be solved by the invention
The purpose of the present invention is to provide a V-ribbed belt that can suppress disturbance and damage of the pitch of the core wires when manufactured by a die-molding method, and that has excellent sound emission resistance and durability even when used in applications where the dynamic tension is high, and a method for manufacturing the V-ribbed belt.
Means for solving the problems
The present inventors have conducted extensive studies to achieve the above object, and as a result, have found the following and completed the present invention: a V-ribbed belt, which is a twisted rope of core wires for forming the V-ribbed belt, is obtained by twisting a high-elongation aramid fiber having an intermediate elongation of 0.8% or more and a tensile elasticity of 50-100 GPa at a load of 4cN/dtex and a low-modulus fiber having a tensile elasticity lower than that of the high-elongation aramid fiber in a mixed manner, wherein the V-ribbed belt can suppress the disorder and damage of the pitch of the core wires during the production by a mold molding method, and can maintain the sound emission resistance and durability even when used in applications having a high dynamic tension.
That is, the V-ribbed belt of the present invention comprises a twisted rope obtained by twisting a high-elongation aramid fiber having an intermediate elongation of 0.8% or more and a tensile elasticity of 50 to 100GPa at a load of 4cN/dtex, and a low-modulus fiber having a tensile elasticity lower than that of the high-elongation aramid fiber. The low-modulus fiber may have a tensile elastic modulus of 20GPa or less. The proportion of the high-elongation aramid fiber can be 60-95% by mass in the twisted rope. The twisted rope may be a twisted rope formed by twisting a plurality of lower twisted threads or a twisted rope formed by twisting a plurality of untwisted threads, and the lower twist coefficient of the twisted rope is 0-6 and the upper twist coefficient of the twisted rope is 2-6. The twisting rope is twisted in the same direction. In the twisted rope with the same twist, the ratio of the upper twist coefficient to the lower twist coefficient of the aramid fiber with high elongation may be 4 to 8 (particularly 5 to 7), and the lower twist coefficient of the aramid fiber with high elongation may be 1 or less. The twisted rope can be twisted, and the lower twist coefficient of the high-elongation aramid fiber is more than 2. The V-ribbed belt of the present invention may have at least a part of the friction transmission surface covered with a fabric. The V-ribbed belt of the present invention may be a V-ribbed belt mounted on an engine mounted with a belt ISG drive.
The present invention also includes a manufacturing method of the V-ribbed belt, including a core wire preparation step of performing a bonding treatment on the twisted rope and preparing a core wire, wherein in the core wire preparation step, the thermal setting elongation is thermally fixed at 3% or less at the time of the heat treatment of the bonding treatment.
Effects of the invention
In the present invention, as a twisted rope for forming a core wire of a V-ribbed belt, a high-elongation aramid fiber having an intermediate elongation of 0.8% or more and a tensile elasticity of 50 to 100GPa at a load of 4cN/dtex and a low-modulus fiber having a lower tensile elasticity than the high-elongation aramid fiber are mixed and twisted, so that disturbance and damage of the pitch of the core wire can be suppressed during production by a die-molding method, and sound emission resistance and durability can be maintained even when the twisted rope is used in an application having a high dynamic tension.
Drawings
Fig. 1 is a schematic cross-sectional view showing an example of a V-ribbed belt of the present invention.
Fig. 2 is a schematic view showing a testing machine for evaluating a bending fatigue test of the core wires obtained in examples and comparative examples.
Fig. 3 is a schematic view showing a testing machine for evaluating a durable running test of the V-ribbed belts obtained in examples and comparative examples.
Fig. 4 is a graph showing the relationship between the ratio of the upper twist multiplier to the lower twist multiplier of the aramid fibers and the service life of the V-ribbed belts in examples 1 to 6 and 11 to 12.
Detailed Description
[ twisted rope ]
The V-ribbed belt of the invention comprises a twisted rope formed by twisting high-elongation aramid fibers having an intermediate elongation of 0.8% or more and a tensile elasticity of 50-100 GPa at a load of 4cN/dtex, and low-modulus fibers having a lower tensile elasticity than the high-elongation aramid fibers. In the present invention, since the aramid fiber having a high elongation and a large tensile elastic modulus is contained, excellent durability is exhibited even in high load transmission. Further, since the low modulus fiber is contained and the high elongation aramid fiber has a relatively high intermediate elongation, the laminate of the constituent materials of the belt including the core wire can be sufficiently expanded in the outer circumferential direction during the belt production, and the belt can be prevented from being disturbed or damaged in the pitch of the core wire, and has excellent durability. The tensile elastic modulus of the low-modulus fiber needs to be small to some extent from the point of ensuring elongation, for example, 20GPa or less.
(high elongation aramid fiber)
The high-elongation aramid fiber as one raw material yarn included in the twisted rope may have an intermediate elongation of 0.8% or more (e.g., 0.8 to 3%) at a load of 4cN/dtex, and may preferably have 0.9% or more (e.g., 0.9 to 2%), and more preferably have 1% or more (e.g., 1 to 1.5%). If the intermediate elongation of the high-elongation aramid fiber is less than 0.8%, the core wire may be damaged by circumferential expansion during belt production, and the durability may be reduced.
In the present specification and claims, the intermediate elongation means an intermediate elongation under a load of 4cN/dtex, and can be measured by a method according to JIS L1017 (2002).
The tensile elastic modulus of the high-elongation aramid fiber is preferably high in order to suppress the belt elongation at the time of use, but if it is too high, the intermediate elongation tends to be small, and therefore it is necessary to adjust the tensile elastic modulus to an appropriate range, and the range is only 50 to 100GPa, but is preferably 50 to 90GPa (for example, 60 to 90GPa), and more preferably 60 to 80GPa (particularly, 60 to 70 GPa).
In the present specification and claims, the tensile modulus can be measured by measuring a load-elongation curve by a method described in JIS L1013(2010) and by a method of obtaining an average inclination in a region where the load is 1000MPa or less.
The high-elongation aramid fiber that is mixed-twisted with the low-modulus fiber itself may be a twisted yarn (under-twisted yarn) or a non-twisted yarn (fiber bundle). The low twist factor of the high-elongation aramid fiber itself may be selected from the range of 0 to 6 degrees, for example, 0.1 to 5, preferably 0.3 to 4 degrees. If the lower twist multiplier is too large, the tensile strength may be reduced, the belt elongation may be increased to cause a transmission failure, or heat generation due to slippage may be increased to reduce the durability.
In particular, when the twisted rope is a straight twist, the low twist factor of the high-elongation aramid fiber may be 3 or less (particularly 1 or less), for example, 0.1 to 3, preferably 0.2 to 1, and more preferably 0.3 to 0.8 (particularly 0.3 to 0.7). Since the bending fatigue resistance is secured to some extent by the forward twist, the lower twist multiplier is preferably small at the point of suppressing the elongation.
On the other hand, when the twisted rope is twisted, the low twist factor of the high-elongation aramid fiber may be 1.5 or more (particularly 2 or more), for example, 1.5 to 6, preferably 2 to 5.5, and more preferably 3 to 5 (particularly 3.5 to 4.5). In contrast to the forward twist, which is excellent in bending fatigue resistance of the structure itself, when the high-elongation aramid fiber is formed into a twisted structure, it is preferable to increase the lower twist factor of the high-elongation aramid fiber. When the lower twist multiplier of the high-elongation aramid fiber is increased, even in the case of a twisted structure, the bending fatigue resistance can be secured and the durability can be improved.
In the present specification and claims, the respective twist multiplier of the lower twist multiplier and the upper twist multiplier can be calculated based on the following expression.
Twist factor [ number of twists (times/m) × v/total fineness (tex) ]/960
The high-elongation aramid fiber as the raw material yarn is usually a para-aramid multifilament yarn including para-aramid fibers. The para-aramid multifilament yarn may be a monofilament yarn including para-aramid fibers, and may include monofilament yarns of other fibers (polyester fibers and the like) if necessary. The proportion of the para-aramid fiber may be 50 mass% or more (particularly 80 to 100 mass%) of the whole monofilament yarn (multifilament yarn), and usually all the monofilament yarns are made of the para-aramid fiber.
The multifilament yarn may include a plurality of monofilament yarns, and may include, for example, about 100 to 5000 monofilament yarns, preferably about 300 to 2000 monofilament yarns, and more preferably about 600 to 1000 monofilament yarns. The monofilament has an average fineness of, for example, 0.8 to 10dtex, preferably 0.8 to 5dtex, and more preferably 1.1 to 1.7 dtex.
The high-elongation aramid fiber as the raw material yarn may be a para-aramid fiber having a single repeating unit (for example, a poly (p-phenylene terephthalamide) fiber, "Twaron (Twaron)" manufactured by imperial corporation, a Kevlar (Kevlar) "manufactured by dongduo corporation), etc.), or a copolymerized para-aramid fiber including a plurality of repeating units (for example, a copolymerized aramid fiber of poly (p-phenylene terephthalamide) and 3, 4' -oxydiphenylene terephthalamide, a aramid (Technora)" manufactured by imperial corporation, etc.).
The number of the high-elongation aramid fibers (multifilament yarn itself) to be mixed with the low-modulus fibers is not particularly limited, and may be one or more, for example, 1 to 10, preferably 2 to 5, and more preferably 3 to 4 (particularly 3).
The proportion of the high-elongation aramid fiber may be about 50 to 99 mass%, for example, 60 to 95 mass%, preferably 60 to 90 mass%, and more preferably 70 to 90 mass% (particularly 75 to 85 mass%) in the twisted rope. If the composition ratio of the high-elongation aramid fiber is too low, the elongation of the belt may increase to cause a transmission failure, or heat generation due to slippage may increase to reduce durability. On the other hand, if the composition ratio is too high, the laminate of the constituent materials of the belt including the core wires cannot be sufficiently expanded in the outer circumferential direction during the belt production, and the pitch of the core wires may be disturbed or the core wires may be damaged, thereby deteriorating the durability of the belt.
The fineness of the high-elongation aramid fibers (each high-elongation aramid fiber in the case of a plurality of high-elongation aramid fibers) mixed with the low-modulus fibers may be selected from the range of about 500 to 3000dtex, or may be, for example, about 600 to 2000dtex, preferably about 700 to 1700dtex, and more preferably about 800 to 1500dtex (particularly about 1000 to 1200 dtex). If the fineness is too small, the elongation may be large or the life may be reduced, whereas if it is too large, the bending fatigue resistance may be reduced and the life may be reduced.
(Low modulus fiber)
The low modulus fiber as the other raw material strand included in the twisted rope may have a lower tensile modulus than the high elongation aramid fiber, but is preferably small in the point where the elongation at the time of belt production can be ensured. Specifically, the low modulus fiber may have a tensile modulus of 20GPa or less, preferably 15GPa or less (for example 10GPa or less), more preferably 8GPa or less (particularly 5GPa or less), for example 0.1 to 10GPa (particularly 1 to 5GPa) or so. The lower limit of the tensile modulus of the low modulus fiber is not particularly limited, but is preferably 0.1GPa or more, for example.
The low modulus fiber co-twisted with the high elongation aramid fiber may be twisted (under-twisted) or untwisted. The low modulus fiber itself may have a twist reduction ratio of 0 to 6, for example, 0.1 to 5, preferably 0.2 to 3, and more preferably 0.3 to 2 (particularly 0.4 to 1). If the lower twist multiplier is too large, the tensile strength may be reduced, the belt elongation may be increased to cause a transmission failure, or heat generation due to slippage may be increased to reduce the durability.
The low modulus fibers as the raw stock line are also typically multifilament strands. The multifilament threads may be formed from either the same type of monofilament thread or different types of monofilament threads.
Examples of the low modulus fiber used as the raw material yarn include natural fibers (e.g., cotton and hemp), regenerated fibers (e.g., rayon and acetate), synthetic fibers (e.g., polyolefin fibers such as polyethylene and polypropylene, styrene-based fibers such as polystyrene, fluorine-based fibers such as polytetrafluoroethylene, acrylic fibers, polyvinyl chloride fibers, polyvinylidene chloride fibers, vinyl alcohol-based fibers such as polyvinyl alcohol, polyamide fibers, low-elongation aramid fibers, polyester fibers, wholly aromatic polyester fibers, and polyurethane fibers), and inorganic fibers (e.g., carbon fibers and glass fibers). These fibers may be used alone or in combination of two or more. Among them, polyamide fibers are preferable, and aliphatic polyamide fibers such as
The number of low modulus fibers (multifilament yarn itself) to be mixed with the high elongation aramid fiber is not particularly limited, and may be one or more, for example, 1 to 5, preferably 1 to 3, and more preferably 1 to 2 (especially 1).
The mass ratio of the high-elongation aramid fiber to the low-modulus fiber may be about 50/50 to 99/1, for example, 60/40 to 95/5, preferably 60/40 to 90/10, and more preferably 70/30 to 90/10 (particularly 75/25 to 85/15).
The fineness of the low modulus fiber (or each low modulus fiber in the case of a plurality of low modulus fibers) mixed with the high elongation aramid fiber may be selected from the range of about 500 to 3000dtex, or may be, for example, about 600 to 2000dtex, preferably about 700 to 1500dtex, and more preferably about 800 to 1200dtex (particularly about 850 to 1000 dtex). If the fineness is too small, the elongation may be large or the life may be reduced, whereas if it is too large, the bending fatigue resistance may be reduced and the life may be reduced.
(characteristics of twisted rope)
The twisted rope may be a twisted rope obtained by twisting a plurality of under-twisted threads (at least one under-twisted thread of high-elongation aramid fiber and at least one under-twisted thread of low-modulus fiber) or a twisted rope (single twist) obtained by twisting a plurality of non-twisted threads (at least one non-twisted thread of high-elongation aramid fiber and at least one non-twisted thread of low-modulus fiber). Among them, the twisted rope is preferably a twisted rope formed by twisting a plurality of lower twisted threads upward, from the point that the elongation of the twisted rope can be increased. In the case of a twisted rope obtained by twisting a lower twisted yarn, the upper and lower twists may be in the same direction, or in opposite directions. Further, a plurality of single twisted threads may be twisted on, and a single twisted thread and a lower twisted thread, or a single twisted thread and a non-twisted thread may be twisted on. Among them, the forward twist is preferable in terms of excellent bending fatigue resistance and improvement in belt life. When the twisted rope is formed by the forward twist, the bending fatigue resistance is excellent, and therefore, even if the twist factor is reduced, the bending fatigue resistance of the core wire or the belt is hard to be reduced. Therefore, the decrease in tensile strength and the increase in elongation can be suppressed by decreasing the twist factor in the forward twisting.
The twist multiplier of the twisted yarn (and the untwisted yarn) may be selected from the range of 0 to 7 (e.g., 0 to 6), for example, 0.1 to 5, preferably 0.3 to 4. In the case where the twisted cord is a straight twist, the lower twist factor (especially, the lower twist factor of the high-elongation aramid core wire) is, for example, about 0.1 to 3, preferably about 0.2 to 2, and more preferably about 0.3 to 1 (especially about 0.4 to 0.8). If the lower twist multiplier is too large, the tensile strength may be reduced, the belt elongation may be increased to cause a transmission failure, or heat generation due to slippage may be increased to reduce the durability.
The upper twist factor of the twisted rope (upper twisted yarn) can be selected from the range of 2 to 6, for example, 2.5 to 5.5, preferably 3 to 5, and more preferably 3 to 4 (especially 3 to 3.5). If the upper twist factor is too large, the tensile strength may be reduced, the belt elongation may be increased to cause a transmission failure, or heat generation due to slippage may be increased to reduce the durability. On the other hand, if the twist multiplier is too small, the bending fatigue resistance may be reduced and the belt durability may be reduced.
In a twisted rope obtained by twisting a lower twisted yarn, the ratio of the upper twist multiplier to the lower twist multiplier of a high-elongation aramid core yarn is important. When the twisted rope is a straight twist, the upper twist factor is preferably larger than the lower twist factor of the high-elongation aramid fiber, and the ratio of the upper twist factor to the lower twist factor (upper twist factor/lower twist factor) of the high-elongation aramid fiber may be selected from the range of 3 to 10, for example, 4 to 8, preferably 4.5 to 8 (for example, 5 to 7.5), and more preferably 5 to 7 (particularly, 6.5 to 7). By increasing the upper twist factor relative to the lower twist factor of the high-elongation aramid fiber, the bending fatigue resistance is improved and the durability can be improved. Although the details of the mechanism for improving the durability are not clear, it is presumed that the disadvantage of the elongation being increased becomes large when both the lower twist and the upper twist are increased, but the balance between the elastic modulus and the bending fatigue resistance is improved by increasing the upper twist and decreasing the lower twist.
On the other hand, when the twisted rope is twisted, the upper twist multiplier is preferably the same as the lower twist multiplier of the high-elongation aramid fiber, and the ratio of the upper twist multiplier to the lower twist multiplier (upper twist multiplier/lower twist multiplier) of the high-elongation aramid fiber may be selected from the range of 0.5 to 2, for example, 0.6 to 1.5, preferably 0.7 to 1.2, and more preferably 0.75 to 1 (particularly 0.8 to 0.9). By increasing the lower twist multiplier of the high-elongation aramid fiber to the same degree as the upper twist multiplier, the bending fatigue resistance can be improved even in the case of the twist.
The total fineness of the twisted rope (upper twisted yarn) can be selected from the range of, for example, 1000 to 10000dtex, for example, 2000 to 8000dtex, preferably 2500 to 7000dtex, and more preferably 3000 to 6000dtex (especially 3500 to 5000 dtex). If the total fineness is too small, the elongation may be large or the life may be reduced. If the total fineness is too large, the bending fatigue resistance may be lowered, and the life may be reduced.
[ core wire preparation Process ]
The V-ribbed belt of the present invention may include the twisted cord, and generally includes a core wire obtained through a core wire preparation step of performing a bonding treatment on the twisted cord.
In the core wire preparation step, a general-purpose adhesion treatment may be performed in order to improve the adhesion between the twisted cord forming the core wire and the rubber. Examples of such an adhesion treatment include a method of dipping into a treatment liquid containing an epoxy compound or a polyisocyanate compound, a method of dipping into an RFL treatment liquid containing resorcinol, formaldehyde and a latex, and a method of dipping into a rubber paste. These treatments may be applied alone or in combination of two or more. In addition to the dipping, the method of spraying or coating may be used, but the dipping is preferable because the point where the adhesive component easily penetrates into the core wire and the point where the thickness of the adhesive layer is easily made uniform.
In particular, in the core wire preparation step, after various adhesive components are adhered, heat treatment may be performed for drying and curing. In particular, after the treatment with the RFL treatment liquid, it is preferable to perform a heat treatment for thermal elongation fixation. The heat-set elongation in the heat treatment may be about 0 to 3%, preferably about 0.1 to 2.5%, and more preferably about 0.5 to 2%. In the present invention, the elongation at vulcanization can be secured by reducing the heat-set elongation, so that the rib shape can be stably formed, and the irregularity or damage of the pitch of the core wire can be suppressed.
In the present specification and claims, the heat-set elongation can be determined from the following equation by measuring the velocities of the core wires at the inlet and outlet of the heat treatment furnace.
Heat-set elongation (%) { (speed of core wire at outlet of heat-treating furnace-speed of core wire at inlet of heat-treating furnace)/speed of core wire at inlet of heat-treating furnace } × 100
[ V type V-ribbed belt ]
The form of the V-ribbed belt of the present invention is not particularly limited as long as it has a plurality of V-ribs extending parallel to each other in the belt longitudinal direction, and for example, the form shown in fig. 1 is illustrated. Fig. 1 is a schematic cross-sectional view showing an example of a V-ribbed belt of the present invention. The V-ribbed belt shown in fig. 1 has a form in which a
The V-ribbed belt of the present invention is not limited to this form, and may be provided with a compression rubber layer having a transmission surface at least a part of which can come into contact with a V-rib groove portion (V-groove portion) of a pulley, and may be provided with an extension layer, a compression rubber layer, and a core wire embedded therebetween in the belt longitudinal direction in a normal case. In the V-ribbed belt of the present invention, for example, the core wires 1 may be embedded between the extension layer 5 and the
At least the
In particular, the V-ribbed belt of the present invention is excellent in sound emission resistance and durability even in applications where high dynamic tension is generated, and therefore, the V-ribbed belt is preferably a V-ribbed belt that is commonly used in applications where high dynamic tension is generated. As such a V-ribbed belt, a V-ribbed belt in which at least a part of the friction transmission surface is covered with a fabric may be mentioned. The fabric may cover at least a part of the friction transmission surface, but usually covers the entire friction transmission surface.
(core wire)
In the adhesive rubber layer 4, the plurality of core wires 1 extend in the belt longitudinal direction, and are arranged at predetermined intervals in the belt width direction.
The average pitch of the core wires (average distance between the centers of adjacent core wires) can be appropriately selected in accordance with the diameter of the core wire and the target tape tensile strength, and is, for example, about 0.6 to 2mm, preferably about 0.8 to 1.5mm, and more preferably about 0.9 to 1.05 mm. If the average pitch of the core wires is too small, the core wires may ride on each other in the belt manufacturing process, and conversely, if it is too large, the tensile strength and tensile modulus of the belt may decrease. The average pitch of the core wires is a value obtained by measuring and averaging the distances between the centers of the adjacent core wires in the cross section of the V-ribbed belt in the width direction at 10. The distance between the centers of the core wires can be measured by using a known device such as a Scanning Electron Microscope (SEM) or a projector.
The core wires may be either S-twist or Z-twist, but S-twist and Z-twist are preferably arranged alternately in order to improve the straightness of the belt. The core wire may be covered with a rubber composition containing a rubber component constituting the adhesive rubber layer in addition to the aforementioned adhesion treatment.
(rubber composition)
The compression rubber layer 2, the adhesive rubber layer 4, and the extension layer 5 may be formed of a rubber composition containing a rubber component, and examples of the rubber component include a rubber capable of being vulcanized or crosslinked, for example, a diene rubber (natural rubber, isoprene rubber, butadiene rubber, chloroprene rubber, Styrene Butadiene Rubber (SBR), acrylonitrile butadiene rubber (nitrile rubber), hydrogenated nitrile rubber, etc.), an ethylene- α -olefin elastomer, a chlorosulfonated polyethylene rubber, an alkylated chlorosulfonated polyethylene rubber, an epichlorohydrin rubber, an acrylic rubber, a silicone rubber, a polyurethane rubber, a fluorine rubber, etc., these rubber components may be used singly or in combination of two or more, preferred rubber components are an ethylene- α -olefin elastomer (ethylene-propylene copolymer (EPM), ethylene-propylene-diene terpolymer (EPDM), etc.) and a chloroprene rubber, and from the viewpoint of ozone resistance, heat resistance, cold resistance, weather resistance and reduction in belt weight, particularly preferred ethylene- α -olefin Elastomer (EPM), ethylene-propylene-diene terpolymer (EPDM), etc.), and particularly preferred elastomer components are ethylene- α to 3680% by mass (particularly 100 to α% by mass).
The rubber composition may further contain short fibers. Examples of the short fibers include polyolefin fibers (e.g., polyethylene fibers and polypropylene fibers), polyamide fibers (e.g.,
The rubber composition may further contain conventional additives. Examples of the conventional additives include a vulcanizing agent or a crosslinking agent (or a crosslinking agent system) (e.g., a sulfur-based vulcanizing agent), a co-crosslinking agent (e.g., bismaleimide system), a vulcanization aid or a vulcanization accelerator (e.g., a thiuram-based accelerator), a vulcanization retarder, a metal oxide (e.g., zinc oxide, magnesium oxide, calcium oxide, barium oxide, iron oxide, copper oxide, titanium oxide, aluminum oxide), a reinforcing agent (e.g., carbon black, silica oxide such as hydrous, a filler (e.g., clay, calcium carbonate, talc, mica), a softener (e.g., an oil such as paraffin oil or naphthene oil), a processing agent or a processing aid (e.g., stearic acid, a metal stearate, wax, paraffin, fatty acid amide), an aging inhibitor (e.g., an oxidation inhibitor, a thermal aging inhibitor, a bending crack inhibitor, an antiozonant), a coloring agent, a tackifier, a plasticizer, Coupling agents (silane coupling agents and the like), stabilizers (ultraviolet absorbers, heat stabilizers and the like), flame retardants, antistatic agents and the like. These additives may be used alone or in combination of two or more. It is noted that the metal oxide may function as a crosslinking agent. In particular, the rubber composition constituting the adhesive rubber layer 4 may contain an adhesion improver (e.g., resorcinol-formaldehyde co-condensate or amino resin).
The rubber compositions constituting the
(canvas cover)
The stretching layer 5 may also be formed of canvas cover. The canvas cover may be formed of a cloth material (preferably woven cloth) such as woven cloth, canvas, knitted cloth, or nonwoven cloth, and if necessary, may be laminated in the above form on the compression rubber layer and/or the adhesive rubber layer after an adhesive treatment such as treatment with RFL treatment liquid (immersion treatment or the like) or rubbing of an adhesive rubber into the cloth material, and lamination (coating) of the adhesive rubber and the cloth material.
(Fabric for covering Friction Transmission surface)
The fabric covering at least a part of the friction transmission surface may be a fabric exemplified in the cover canvas, or may be subjected to an adhesion treatment in the same manner as the cover canvas. Among the above fabrics, a knitted fabric is preferable as the fabric covering the friction transmitting surface in view of excellent durability and stretchability. The material of the knitted fabric is not particularly limited, and examples thereof include low modulus fibers and short fibers blended with the tape. The knitted fabric may be a knitted fabric of a cellulose fiber (e.g., cotton yarn) or a polyester fiber (e.g., PTT/PET composite fiber).
[ method for producing V-ribbed Belt ]
The method for manufacturing a V-ribbed belt of the present invention may be any method including the above-described core-wire preparation step, and a conventional method for manufacturing a V-ribbed belt may be used.
As a first manufacturing method, the following method can be exemplified: the unvulcanized sleeve having a rib shape on the surface is obtained by a step of forming an unvulcanized sleeve in which an unvulcanized stretched rubber sheet, a core wire, and an unvulcanized compressed rubber sheet are arranged in this order from the inner peripheral side in an inner mold to which the plastic sheath is fitted, and a step of expanding the plastic sheath to press the unvulcanized sleeve from the inner peripheral side against an outer mold having a rib-shaped imprint and vulcanizing the unvulcanized sleeve.
As a second manufacturing method, the following method can be exemplified: a vulcanized sleeve having a rib shape on the surface is obtained by a step of forming a first unvulcanized sleeve in which an unvulcanized compressed rubber sheet is arranged in an inner mold to which a plastic sheath is attached, a step of expanding the plastic sheath to press the first unvulcanized sleeve against an outer mold having a rib-shaped imprint from the inner periphery side to form a preliminary molded body in which a rib shape is engraved on the surface, a step of separating the inner mold to which the plastic sheath is attached from the outer mold to which the preliminary molded body is attached by releasing the expansion of the plastic sheath, and then arranging an unvulcanized stretched rubber sheet and a core wire in this order in the inner mold to which the plastic sheath is attached to form a second unvulcanized sleeve, and a step of re-expanding the plastic sheath to press the second unvulcanized sleeve against the outer mold to which the preliminary molded body is attached from the inner periphery side to integrally vulcanize the second unvulcanized sleeve with the preliminary molded.
When the friction transmission surface is covered with a fabric, the fabric may be provided on the outermost layer (outer circumferential side) of the unvulcanized sleeve that is in contact with the outer mold. Further, an adhesive rubber sheet may be provided between the core wire and the extension rubber sheet or/and between the core wire and the compression rubber sheet.
Among these methods, the first manufacturing method is simple in process and excellent in productivity, and the second manufacturing method can reduce the expansion rate of the core wire by reducing the interval between the inner mold and the outer mold, so that damage to the core wire can be suppressed, and a decrease in the durability of the belt can be suppressed. The manufacturing method may be selected according to the items of priority in productivity and durability, but the second manufacturing method is preferably applied according to the object of the present invention.
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