WO2018235755A1

WO2018235755A1 - V-ribbed belt and method for manufacturing same

Info

Publication number: WO2018235755A1
Application number: PCT/JP2018/023040
Authority: WO
Inventors: 和貴横山; 博樹武市; 長谷川　新; 西山　健; 学光冨
Original assignee: 三ツ星ベルト株式会社
Priority date: 2017-06-20
Filing date: 2018-06-15
Publication date: 2018-12-27

Abstract

The present invention relates to a V-ribbed belt that has a medium elongation of 0.8% or more when the load of 4 cN/dtex is applied, and that contains a twisted cord in which a high-elongation aramid fiber having a tensile modulus of 50-100 GPa and a low-modulus fiber having a lower tensile modulus than the high-elongation aramid fiber are blended and twisted.

Description

V-ribbed belt and method of manufacturing the same

The present invention relates to a V-ribbed belt including a twisted cord in which aramid fibers and low modulus fibers are mixed and twisted as a core wire, and a method of manufacturing the same.

Recently, as the fuel efficiency regulations of automobiles are intensified, vehicles equipped with an idling stop mechanism are increasing as one of the fuel efficiency improvement measures for engines. Then, in engine restart from an idling stop state, belt-type ISG (Integrated Starter Generator) drive for driving a crankshaft from an alternator via an accessory drive belt has become widespread. In belt-type ISG drive, high dynamic tension is generated in the belt as compared to a normal engine without ISG. For example, if it is assumed that the dynamic tension generated in the belt is about 250 N / rib when the ISG is not mounted, the dynamic tension about 350 N / rib is generated in the belt when the belt type ISG drive is mounted. It is a condition. Therefore, V-ribbed belts for accessory drive used in engines equipped with belt type ISG drive are required to have high tensile elastic modulus in order to keep the elongation of the belt small even when high dynamic tension occurs. There is. Therefore, a core wire containing a fiber having a small elongation and a high elastic modulus such as aramid fiber is preferably used. In addition, since the dynamic tension is high, a very high level of sound resistance and durability is also required, and a configuration in which the rib surface (frictional transmission surface) is coated with a fabric is preferably used.

The V-ribbed belt in which the rib surface is coated with a fabric is usually manufactured by a molding method. However, in the molding method, since it is necessary to expand the laminated body of the belt constituent material including the core wire in the outer circumferential direction, it is difficult to apply a core wire with a small elongation. If the elongation of the core wire is too small, the laminate can not be expanded sufficiently and the rib shape becomes defective, the pitch of the core wire (line of the core wire in the belt width direction) is disturbed, or the core wire is damaged. As a result, problems such as reduction in tensile strength and durability of the transmission belt occur. As a countermeasure, Japanese Patent Laid-Open Publication No. 2008-100365 (Patent Document 1) discloses a method of manufacturing a power transmission belt using a twisted yarn cord in which aramid fibers and fibers having a relatively large intermediate elongation are mixed and twisted. ing. In this document, by mixing and twisting fibers having relatively high intermediate elongation, such as polyester fibers and polyamide fibers, with rigid aramid fibers, the core pitch is defective or the core is formed in pressure molding in a molding method as well. It is described that high modulus transmission belts can be manufactured that can suppress line damage and that can also be used in drives with large engine load fluctuations.

However, even with this transmission belt, the stretch of the twisted yarn cord at the time of manufacturing the belt and the durability of the belt may not be sufficient in some cases, and improvements have been desired.

Japanese Patent Laid-Open Publication No. 2008-100365 (claim 1, paragraph [0017] [0027])

The object of the present invention is to provide a V-ribbed belt which can suppress the distortion and damage of the core wire pitch at the time of manufacturing by a molding method and is excellent in sound resistance and durability even when used in applications with high dynamic tension It is in providing the manufacturing method.

The inventors of the present invention conducted intensive studies to achieve the above problems, and as a twisted cord for forming a core of a V-ribbed belt, the intermediate elongation at a load of 4 cN / dtex is 0.8% or more, and V-ribbed belt is manufactured by a molding method by mixing and twisting a high elongation aramid fiber having a tensile modulus of 50 to 100 GPa and a low modulus fiber having a tensile modulus lower than that of the high elongation aramid fiber. At the same time, it has been found that it is possible to suppress the distortion and damage of the pitch of the core wire and to maintain the sound resistance and durability even when used in applications with high dynamic tension, thus completing the present invention.

That is, the V-ribbed belt of the present invention has a high elongation aramid fiber having an intermediate elongation of 0.8% or more at a load of 4 cN / dtex and a tensile modulus of 50 to 100 GPa, and the high elongation aramid fiber It includes a twist cord mixed and twisted with a low modulus fiber having a lower tensile modulus than that. The low modulus fiber may have a tensile modulus of 20 GPa or less. The proportion of the high elongation aramid fiber may be 60 to 95% by mass in the twist cord. The twist cord is a twist cord obtained by twisting a plurality of first twist yarns or a twist cord obtained by twisting a plurality of non-twist yarns, and the twist twist coefficient of this twist cord is 0 to 6 and the upper twist coefficient is 2 to It may be six. The twist cord may be rung twist. The ratio of the upper twist coefficient to the lower twist coefficient of the high elongation aramid fiber may be 4 to 8 (particularly 5 to 7) in the Lang stranded twisted cord, and the high twist aramid fiber has a lower twist coefficient of 1 or less It may be The twist cord may be a multi-twist, and a high twist aramid fiber may have a first twist coefficient of 2 or more. In the V-ribbed belt of the present invention, at least a part of the friction transmission surface may be coated with a fabric. The V-ribbed belt of the present invention may be a V-ribbed belt mounted on an engine equipped with a belt type ISG drive.

The present invention relates to the method for producing a V-ribbed belt including a cord preparation step of preparing a cord by bonding the twist cord, and in the cord preparation step, a heat set draw ratio during heat treatment of adhesion processing. The manufacturing method which carries out heat extension fixation by 3% or less is also included.

In the present invention, as a twisted cord for forming a core of a V-ribbed belt, a high elongation aramid having an intermediate elongation of 0.8% or more at a load of 4 cN / dtex and a tensile modulus of 50 to 100 GPa Since the fiber and the low modulus fiber having a tensile modulus of elasticity lower than that of the high elongation aramid fiber are mixed and twisted, it is possible to suppress the distortion and damage of the core wire pitch at the time of production by the molding method and Sound resistance and durability can be maintained even when used in applications with high specific tension.

FIG. 1 is a schematic cross-sectional view showing an example of the V-ribbed belt of the present invention. FIG. 2 is a schematic view showing a tester for evaluating the bending fatigue test of the cord obtained in the example and the comparative example. FIG. 3 is a schematic view showing a tester for evaluating the endurance running test of the V-ribbed belt obtained in Examples and Comparative Examples. FIG. 4 is a graph showing the relationship between the ratio of the upper twist coefficient to the upper twist coefficient of the aramid fibers in Examples 1 to 6 and 11 to 12, and the running life of the V-ribbed belt.

[Twist cord]
The V-ribbed belt of the present invention has a high elongation aramid fiber having an intermediate elongation of 0.8% or more at a load of 4 cN / dtex and a tensile elastic modulus of 50 to 100 GPa, and this high elongation aramid fiber It includes a twist cord mixed and twisted with a low modulus fiber having a low tensile modulus. In the present invention, since the high elongation aramid fiber having a large tensile elastic modulus is included, excellent durability is exhibited even in high load transmission. Further, since the low elongation fiber is included and the intermediate elongation of the high elongation aramid fiber is relatively large, the laminated body of the belt constituent material including the core wire can be sufficiently expanded in the circumferential direction at the time of belt manufacture, The distortion and damage of the pitch of the core wire are suppressed, and the durability of the belt is excellent. The tensile modulus of the low modulus fiber needs to be small to some extent, for example, 20 GPa or less in order to secure elongation.

(High elongation aramid fiber)
The high elongation aramid fiber, which is one of the raw yarns contained in the twisted cord, may have an intermediate elongation of 0.8% or more (eg, 0.8 to 3%) at a load of 4 cN / dtex, preferably 0 It may be 9% or more (eg, 0.9 to 2%), more preferably 1% or more (eg, 1 to 1.5%). If the intermediate elongation of the high elongation aramid fiber is less than 0.8%, the cord may be damaged due to expansion in the circumferential direction at the time of manufacturing the belt, and the durability may be lowered.

In the present specification and claims, “intermediate elongation” means intermediate elongation under a load of 4 cN / dtex and can be measured by a method according to JIS L1017 (2002).

The tensile modulus of high elongation aramid fiber is preferably high to suppress belt elongation during use, but if too high it tends to decrease the intermediate elongation, so it is adjusted to an appropriate range The necessary range is 50 to 100 GPa, preferably 50 to 90 GPa (eg 60 to 90 GPa), more preferably 60 to 80 GPa (especially 60 to 70 GPa).

In the present specification and claims, the tensile elastic modulus can be measured by measuring a load-elongation curve according to the method described in JIS L1013 (2010), and determining the average slope of a region under a load of 1000 MPa.

The high elongation aramid fiber itself to be mixed and twisted with the low modulus fiber may be a twisted yarn (bottom twist yarn) or may be a non-twist yarn (fiber bundle). The lower twist coefficient of the high elongation aramid fiber itself can be selected from the range of about 0 to 6, for example, about 0.1 to 5, preferably about 0.3 to 4. If the lower twist coefficient is too large, tensile strength may decrease, belt elongation may increase, transmission failure may occur, heat generation due to slip may increase, and durability may decrease.

In particular, when the twist cord is a rung twist, the lower twist coefficient 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 further Preferably, it may be about 0.3 to 0.8 (especially 0.3 to 0.7). Since the bending fatigue resistance is secured to some extent by rung twisting, it is preferable that the lower twisting coefficient be as small as possible from the viewpoint of suppressing the elongation.

On the other hand, when the twist cord is a multi-twist, the lower twist coefficient 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. More preferably, it may be about 3 to 5 (especially 3.5 to 4.5). Unlike Lang twist which is excellent in bending fatigue resistance, it is preferable to increase the lower twist coefficient of high elongation aramid fiber in the case of multi-twist configuration. When the lower twist coefficient of the high elongation aramid fiber is increased, the bending fatigue resistance can be secured and the durability can be improved even in the multi-twist configuration.

In the present specification and claims, each twisting coefficient of the first twisting coefficient and the upper twisting coefficient can be calculated based on the following equation.

Twist factor = [twist number (turns / m) × √total fineness (tex)] / 960

The high elongation aramid fibers, which are raw yarns, are usually para-aramid multifilament yarns containing para-aramid fibers. Furthermore, the para-aramid multifilament yarn may include monofilament yarns of para-aramid fibers, and may include monofilament yarns of other fibers (such as polyester fibers), if necessary. The proportion of the para-aramid fiber may be 50% by mass or more (particularly 80 to 100% by mass) based on the whole monofilament yarn (multifilament yarn), and generally all monofilament yarns are composed of para-aramid fibers ing.

The multifilament yarn may contain a plurality of monofilament yarns, and may contain, for example, about 100 to 5000, preferably 300 to 2000, and more preferably about 600 to 1000 monofilament yarns. The average fineness of the monofilament yarn may be, for example, about 0.8 to 10 dtex, preferably about 0.8 to 5 dtex, and more preferably about 1.1 to 1.7 dtex.

The high elongation aramid fiber, which is a raw yarn, is a single repeating unit of para-aramid fiber (for example, polyparaphenylene terephthalamide fiber made by Teijin Ltd. “Twaron” or Toray DuPont Ltd. “Kevlar” etc. Copolymerized para-aramid fiber (for example, co-polymerized aramid fiber of polyparaphenylene terephthalamide and 3,4'-oxydiphenylene terephthalamide), which may be a plurality of repeating units (for example, Teijin Ltd.) It may be manufactured by "Technola" or the like.

The number of high elongation aramid fibers (multifilament yarns themselves) mixed with low modulus fibers is not particularly limited, and may be one or more, for example, 1 to 10, preferably 2 to 5, further Preferably, it is about 3 to 4 (especially 3).

The proportion of the high elongation aramid fiber may be 50 to 99% by mass in the twisted cord, for example, 60 to 95% by mass, preferably 60 to 90% by mass, more preferably 70 to 90% by mass It may be about 85% by mass). If the proportion of the high elongation aramid fiber is too low, the belt may be stretched to cause transmission failure or heat generation due to slip may be increased to lower the durability. On the other hand, if the component ratio is too high, it is not possible to expand the laminate of the belt component materials including the core wire in the circumferential direction sufficiently at the time of belt manufacture, the pitch of the core wire is disturbed or the core wire is damaged. There is a risk that the durability of the

The fineness of the high elongation aramid fiber (in the case of plural fibers, each high elongation aramid fiber) to be mixed and twisted with the low modulus fiber can be selected from the range of about 500 to 3000 dtex, for example 600 to 2000 dtex, preferably 700 to 1700 dtex, More preferably, it may be about 800 to 1,500 dtex (particularly about 1,000 to 1,200 dtex). If the fineness is too small, the elongation may be increased or the life may be decreased. On the other hand, if it is too large, the bending fatigue resistance may be reduced to deteriorate the life.

(Low modulus fiber)
The low modulus fiber, which is the other raw yarn contained in the twisted cord, may have a tensile modulus lower than that of the high elongation aramid fiber, but the smaller one is because it can secure the elongation at the time of belt production. preferable. Specifically, the tensile modulus of a low modulus fiber may be, for example, 20 GPa or less, preferably 15 GPa or less (eg, 10 GPa or less), more preferably 8 GPa or less (particularly 5 GPa or less), for example, 0.1 to 10 GPa (In particular, about 1 to 5 GPa). Further, the lower limit value of the tensile modulus of elasticity of the low modulus fiber is not particularly limited, but for example, 0.1 GPa or more is preferable.

The low modulus fiber itself to be mixed and twisted with the high elongation aramid fiber may also be a twisted yarn (bottom twisted yarn) or a non-twisted yarn. The lower modulus fiber itself can be selected from the range of about 0 to 6, for example, 0.1 to 5, preferably 0.2 to 3, more preferably 0.3 to 2 (particularly 0.4 to 1). ) Degree. If the lower twist coefficient is too large, tensile strength may decrease, belt elongation may increase, transmission failure may occur, heat generation due to slip may increase, and durability may decrease.

Low modulus fibers, which are raw yarns, are also usually multifilament yarns. The multifilament yarn may be formed of the same kind of monofilament yarn or may be formed of different kinds of monofilament yarn.

The low modulus fibers, which are raw yarns, include, for example, natural fibers (cotton, hemp, etc.), regenerated fibers (rayon, acetate, etc.), synthetic fibers (polyolefin fibers such as polyethylene and polypropylene, styrene fibers such as polystyrene, etc.) Fluorine-based fibers such as ethylene, acrylic fibers, polyvinyl chloride fibers, polyvinylidene chloride fibers, vinyl alcohol fibers such as polyvinyl alcohol, polyamide fibers, low elongation aramid fibers, polyester fibers, wholly aromatic polyester fibers, polyurethane fibers Etc.), inorganic fibers (carbon fibers, glass fibers, etc.) and the like. These fibers can be used alone or in combination of two or more. Among these, polyamide fibers are preferable, and aliphatic polyamide fibers such as nylon 6 and nylon 66 are particularly preferable.

The number of low modulus fibers (multifilament yarns themselves) mixed with high elongation aramid fibers is not particularly limited, and may be one or more, for example, 1 to 5, preferably 1 to 3, and further Preferably, it is about 1 to 2 (especially 1).

The mass ratio of the high elongation aramid fiber to the low modulus fiber may be (high elongation aramid fiber / low modulus fiber) = about 50/50 to 99/1, for example 60/40 to 95/5, It is preferably about 60/40 to 90/10, more preferably about 70/30 to 90/10 (particularly about 75/25 to 85/15).

The fineness of low modulus fibers (in the case of plural fibers, each low modulus fiber) to be mixed and twisted with high elongation aramid fibers can be selected from the range of about 500 to 3000 dtex, for example, 600 to 2000 dtex, preferably 700 to 1500 dtex, and more preferably May be on the order of 800 to 1200 dtex (especially 850 to 1000 dtex). If the fineness is too small, the elongation may increase or the life may decrease. On the other hand, if the size is too large, the bending fatigue resistance may decrease to deteriorate the life.

(Characteristics of twist cord)
The twist cord may be a twist cord obtained by twisting a plurality of lower twist yarns (a lower twist yarn of one or more high elongation aramid fibers and a lower twist yarn of one or more low modulus fibers), and a plurality of non-twist yarns ( It may be a twist cord (one twist) obtained by twisting one or more non-twisted yarns of high elongation aramid fibers and one or more low modulus fibers). Among these, it is preferable that the twist cord is a twist cord obtained by twisting a plurality of first twist yarns in order to increase the elongation of the twist cord. In the case of a twisted cord in which the lower twist yarn is top-twisted, the direction of the first twist and the upper twist may be the same rung twist, or may be opposite plied twists. In addition, a plurality of single-twisted yarns may be top-twisted, or a single-twisted yarn and a lower-twist yarn, or a single-twisted yarn and a non-twisted yarn may be top-twisted. Among them, Lang twist is preferable in terms of excellent bending fatigue resistance and improvement in the belt life. When the twisted cord is constituted by rung twist, since the bending fatigue resistance is excellent, the bending fatigue resistance of the core wire and the belt does not easily decrease even if the twist coefficient is reduced. Therefore, the decrease in tensile strength and the increase in elongation can be suppressed by reducing the twist coefficient in rung twisting.

The lower twist coefficient of the lower twist yarn (and non-twist yarn) can be selected from the range of 0 to 7 (eg, 0 to 6), and is, for example, about 0.1 to 5, preferably about 0.3 to 4. When the twist cord is a rung twist, the first twist coefficient (in particular, the first twist coefficient of high elongation aramid core wire) is, for example, 0.1 to 3, preferably 0.2 to 2, and more preferably 0.3. It is approximately 1 to 1 (especially 0.4 to 0.8). If the lower twist coefficient is too large, tensile strength may decrease, belt elongation may increase, transmission failure may occur, heat generation due to slip may increase, and durability may decrease.

The upper twist coefficient of the twisted cord (upper twisted yarn) can be selected from the range of 2 to 6, for example, 2.5 to 5.5, preferably 3 to 5, more preferably 3 to 4 (especially 3 to 3.5) or so It is. If the upper twist coefficient is too large, tensile strength may decrease, belt elongation may increase, transmission failure may occur, heat generation due to slip may increase, and durability may decrease. On the other hand, when the upper twist coefficient is too small, there is a possibility that the bending fatigue resistance may be reduced and the belt durability may be reduced.

In the twist cord in which the lower twist yarn is top-twisted, the ratio of the upper twist coefficient to the first twist coefficient of the high elongation aramid core wire is important. When the twist cord is rung twist, the upper twist coefficient is preferably larger than the lower twist coefficient of the high elongation aramid fiber, and the ratio of the upper twist coefficient to the lower twist coefficient of the high elongation aramid fiber (upper twist coefficient / lower The twist coefficient) can be selected from the range of 3 to 10, for example, 4 to 8, preferably 4.5 to 8 (eg 5 to 7.5), more preferably 5 to 7 (especially 6.5 to 7) is there. The bending fatigue resistance can be improved and the durability can be improved by increasing the upper twist coefficient with respect to the lower twist coefficient of the high elongation aramid fiber. Although the details of the mechanism for improving the durability are unknown, increasing both the lower twist and the upper twist increases the demerit that the elongation increases, but reduces the lower twist and increases the upper twist so that the elasticity is improved. It can be estimated that the balance between the rate and the bending fatigue resistance is improved.

On the other hand, when the twist cord is a multi-twist, it is preferable that the upper twist coefficient is about the same as the lower twist coefficient of the high elongation aramid fiber, and the ratio of the upper twist coefficient to the lower twist coefficient of the high elongation aramid fiber (upper The twist coefficient / bottom twist coefficient) can be selected from the range of 0.5 to 2, and is, for example, 0.6 to 1.5, preferably 0.7 to 1.2, more preferably 0.75 to 1 (in particular 0. 1). 8 to 0.9). By increasing the lower twist coefficient of the high elongation aramid fiber to be equal to the upper twist coefficient, it is possible to improve the bending fatigue resistance even in the case of multiple twist.

The total fineness of the twisted cord (upper twisted yarn) can be selected, for example, in the range of about 1000 to 10000 dtex, for example, 2000 to 8000 dtex, preferably 2500 to 7000 dtex, more preferably 3000 to 6000 dtex (particularly about 3500 to 5000 dtex). If the total fineness is too small, the elongation may be increased or the life may be reduced. If the total fineness is too large, the bending fatigue resistance may be reduced to reduce the life.

[Core wire preparation process]
The V-ribbed belt of the present invention only needs to contain the twisted cord, and usually includes a cord obtained through a cord preparation step of subjecting the twisted cord to adhesion treatment.

In the cord preparation step, a general-purpose adhesion treatment may be performed to enhance the adhesion between the twisted cord forming the cord and the rubber. Examples of such adhesion treatment include a method of immersion in a treatment solution containing an epoxy compound or a polyisocyanate compound, a method of immersion in an RFL treatment solution containing resorcinol, formaldehyde and a latex, a method of immersion in a rubber paste, and the like. These treatments may be applied alone or in combination of two or more. In addition to immersion, other methods such as spraying and coating may be used, but immersion is preferable in terms of easily infiltrating the adhesive component to the inside of the cord and in terms of making the thickness of the adhesive layer uniform.

In particular, in the cord preparation step, heat treatment may be performed for drying or curing after various adhesive components are attached. In particular, after the treatment with the RFL treatment solution, it is preferable to carry out a heat treatment in order to thermally fix and fix. The heat setting stretch ratio during this 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, since the elongation allowance at the time of vulcanization can be secured by reducing the heat setting stretch ratio, the rib shape can be stably formed, and the disturbance and damage of the core wire pitch can be suppressed.

In the present specification and claims, the heat set draw ratio can be determined from the following equation by measuring the velocity of the core of the heat treatment furnace at the inlet and outlet.

Heat setting draw ratio (%) = {(speed of core at exit of heat treatment furnace-speed of core at entrance of heat treatment furnace) / speed of core at entrance of heat treatment furnace} × 100

[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-rib portions extending in parallel to each other along the longitudinal direction of the belt, and the form shown in FIG. FIG. 1 is a schematic cross-sectional view showing an example of the V-ribbed belt of the present invention. The V-ribbed belt shown in FIG. 1 comprises a compression rubber layer 2, an adhesive rubber layer 4 in which the core wire 1 is embedded in the longitudinal direction of the belt, and a cover canvas (in order from the lower surface (inner peripheral surface) to the upper surface (rear surface) It has a form in which the stretch layer 5 composed of a woven fabric, a knitted fabric, a non-woven fabric or the like) or a rubber composition is laminated. A plurality of V-shaped grooves extending in the longitudinal direction of the belt are formed in the compression rubber layer 2, and a plurality of V-ribs 3 (in FIG. 1) shown in FIG. In this case, four of them are formed, and the two inclined surfaces (surfaces) of the respective V rib portions 3 form friction transmission surfaces, and transmit power (friction transmission) in contact with the pulleys.

The V-ribbed belt of the present invention is not limited to this form, as long as at least a portion thereof has a compressed rubber layer having a transmission surface capable of contacting the V-rib groove (V groove) of the pulley. It is sufficient to provide a layer, a compressed rubber layer, and a core wire embedded along the longitudinal direction of the belt. In the V-ribbed belt of the present invention, for example, the core wire 1 may be embedded between the stretch layer 5 and the compressed rubber layer 2 without providing the adhesive rubber layer 4. Furthermore, the adhesive rubber layer 4 is provided on either the compression rubber layer 2 or the stretch layer 5, and the core wire 1 is provided between the adhesive rubber layer 4 (the compression rubber layer 2 side) and the stretch layer 5 or the adhesive rubber layer 4 It may be embedded between the (stretching layer 5 side) and the compression rubber layer 2.

In addition, it is sufficient if at least the compressed rubber layer 2 is formed of a rubber composition described in detail below, and the adhesive rubber layer 4 is formed of a conventional rubber composition used as an adhesive rubber layer. Preferably, the stretch layer 5 may be formed of a conventional cover canvas or rubber composition used as a stretch layer, and may not be formed of the same rubber composition as the compressed rubber layer 2.

In particular, since the V-ribbed belt of the present invention is excellent in sound resistance and durability even in applications where high dynamic tension is generated, it is preferable that the V-ribbed belt is generally used in applications with high dynamic tension. As such a V-ribbed belt, a V-ribbed belt in which at least a part of the friction transmission surface is coated with a fabric can be mentioned. The fabric may cover at least a part of the friction transmission surface, but usually covers the entire friction transmission surface.

(Heart line)
In the adhesive rubber layer 4, a plurality of core wires 1 respectively extend in the longitudinal direction of the belt and are arranged apart from each other at a predetermined pitch in the width direction of the belt.

The average pitch of the cords (the average distance between the centers of adjacent cords) can be appropriately selected according to the core diameter and the desired belt tensile strength, and is, for example, 0.6 to 2 mm, preferably 0.8 to 1. The thickness is preferably 5 mm, more preferably 0.9 to 1.05 mm. If the average pitch of the cords is too small, there is a risk that the cords will run over each other in the belt manufacturing process, and if too large, the tensile strength and tensile modulus of the belt may be reduced. The average pitch of cords is a value obtained by measuring the distances between the centers of adjacent cords at ten cross sections in the width direction of the V-ribbed belt and averaging them. The distance between the centers of the core wire can be measured using a known device such as a scanning electron microscope (SEM) or a projector.

The core wire may be either S-twist or Z-twist, but it is preferable to alternately arrange S-twist and Z-twist in order to enhance the straightness of the belt. The core wire may be coated with a rubber composition containing a rubber component that constitutes 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 stretch layer 5 may be formed of a rubber composition containing a rubber component. As the rubber component, a vulcanizable or crosslinkable rubber may be used, for example, diene rubber (natural rubber, isoprene rubber, butadiene rubber, chloroprene rubber, styrene butadiene rubber (SBR), acrylonitrile butadiene rubber (nitrile rubber), Hydrogenated nitrile rubber and the like), ethylene-α-olefin elastomer, chlorosulfonated polyethylene rubber, alkylated chlorosulfonated polyethylene rubber, epichlorohydrin rubber, acrylic rubber, silicone rubber, urethane rubber, fluororubber and the like. These rubber components can be used alone or in combination of two or more. Preferred rubber components are ethylene-α-olefin elastomers (ethylene-propylene copolymer (EPM), ethylene-propylene-diene terpolymer (EPDM), etc.) and chloroprene rubber. Furthermore, from the viewpoint of having ozone resistance, heat resistance, cold resistance and weather resistance and being able to reduce the belt weight, ethylene-α-olefin elastomer (ethylene-propylene copolymer (EPM), ethylene-propylene-diene ternary resin Copolymers (EPDM) etc.) are particularly preferred. When the rubber component contains an ethylene-α-olefin elastomer, the proportion of the ethylene-α-olefin elastomer in the rubber component may be 50% by mass or more (particularly about 80 to 100% by mass), 100% by mass (ethylene Particular preference is given to -α-olefin elastomers).

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

The rubber composition may further contain conventional additives. Commonly used additives include, for example, a vulcanizing agent or a crosslinking agent (or a crosslinking agent system) (such as a sulfur-based vulcanizing agent), a co-crosslinking agent (such as bismaleimides), a vulcanization aid or a vulcanization accelerator ( Thiuram accelerators etc.), vulcanization retarders, metal oxides (zinc oxide, magnesium oxide, calcium oxide, barium oxide, iron oxide, copper oxide, copper oxide, aluminum oxide etc.), reinforcing agents (eg carbon black and the like) , Silicon oxides such as hydrous silica, fillers (clay, calcium carbonate, talc, mica etc.), softeners (eg paraffin oils, oils such as naphthenic oils etc), processing agents or processing aids (stearin Acids, metal stearates, waxes, paraffins, fatty acid amides, etc., anti-aging agents (antioxidants, thermal anti-aging agents, flex crack inhibitors, anti-ozonants, etc.), colorants, tackifiers , Plasticizers, coupling agents (silane coupling agent, etc.), stabilizers (UV absorbers, heat stabilizers, etc.), flame retardants, antistatic agents and the like. These additives may be used alone or in combination of two or more. The metal oxide may act as a crosslinking agent. Further, the rubber composition constituting the adhesive rubber layer 4 may particularly contain an adhesion improver (resorcinol-formaldehyde cocondensate, amino resin, etc.).

The rubber compositions constituting the compression rubber layer 2, the adhesive rubber layer 4 and the stretch layer 5 may be identical to one another or may be different from one another. Similarly, the short fibers contained in the compression rubber layer 2, the adhesive rubber layer 4 and the stretch layer 5 may be identical to one another or may be different from one another.

(Cover canvas)
The stretch layer 5 may be formed of a cover canvas. The cover canvas can be formed of, for example, a woven fabric, a wide angle canvas, a knitted fabric, a cloth material (preferably a woven fabric) such as a non-woven fabric, and the like. Etc.), rubbing the adhesive rubber into the cloth material, or laminating (coating) the adhesive rubber and the cloth material, and then laminating to the compressed rubber layer and / or the adhesive rubber layer in the form described above. Good.

(Fabric covering the friction transmission surface)
As a fabric for covering at least a part of the friction transmission surface, the cloth material exemplified for the cover canvas can be used, and may be treated in the same manner as the cover canvas. Among the above-mentioned cloth materials, as a cloth for covering the friction transmission surface, a knitted cloth is preferable in terms of excellent durability and extensibility. The material of the knitted fabric is not particularly limited, and examples thereof include low modulus fibers and fibers exemplified as short fibers mixed in a belt. The knitted fabric may be a knitted fabric of cellulosic fibers (eg, cotton yarn) and polyester fibers (such as PTT / PET conjugated fibers).

[Method of manufacturing V-ribbed belt]
The method for producing the V-ribbed belt of the present invention may include the above-described cord preparation step, and a conventional method for producing a V-ribbed belt can be used.

As a first manufacturing method, 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 to an inner mold equipped with a plastic jacket The method of obtaining a vulcanized sleeve having a rib shape on the surface can be exemplified through a step of expanding a plasticity jacket and pressing and vulcanizing an unvulcanized sleeve from the inner peripheral side to an outer mold having rib-shaped imprints. .

As a second manufacturing method, a step of forming a first unvulcanized sleeve in which an unvulcanized compressed rubber sheet is disposed on an inner mold mounted with a plastic jacket, the plastic jacket is expanded to form an outer mold having a rib-shaped impression The first unvulcanized sleeve is pressed from the inner circumferential side to form a preform on which the rib shape is engraved on the surface, and the plastic jacket is released from the outer mold in which the preform is brought into close contact by releasing the expansion of the plastic jacket. And separating the unvulcanized stretchable rubber sheet and the core wire sequentially from the inner mold fitted with the plastic jacket to form a second unvulcanized sleeve, and further expanding the plastic jacket again Through the step of pressing the second unvulcanized sleeve from the inner circumferential side to the outer mold to which the preformed body is adhered and vulcanizing integrally with the preformed body, a vulcanized sleeve having a rib shape on the surface Get The law can be exemplified.

In addition, when covering a friction transmission surface with a fabric, you may provide a fabric in the outermost layer (periphery side) of the unvulcanized sleeve which contact | abuts an outer mold | type. In addition, an adhesive rubber sheet may be provided between the core wire and the stretch rubber sheet or / and between the core wire and the compression rubber sheet.

Among these methods, the first manufacturing method has a simple process and is excellent in productivity, and the second manufacturing method can reduce the expansion ratio of the core wire by reducing the distance between the inner mold and the outer mold. Therefore, damage to the core wire can be suppressed, and a decrease in the durability of the belt can be suppressed. Among the productivity and durability, the manufacturing method can be selected according to the priority items, but for the purpose of the present invention, it is preferable to apply the second manufacturing method.

The present invention will be described in more detail based on examples given below, but the present invention is not limited by these examples. In addition, the detail of the raw material used in the Example and the evaluation method of the measured evaluation item are shown below.

[material]
(Twist cord)
Aramid 1: Teijin Ltd. "Technola (registered trademark)", middle elongation 0.9%, tensile modulus 70 GPa
Aramid 2: Teijin Ltd. “Twaron (registered trademark)”, medium elongation 1.0%, tensile modulus 60 GPa (low elasticity type)
Aramid 3: Teijin Ltd. “Twaron (registered trademark)”, medium elongation 0.6%, tensile modulus 80 GPa (standard type)
Aliphatic polyamide: "Reona (registered trademark) nylon 66" manufactured by Asahi Kasei Co., Ltd., intermediate elongation 11%, tensile modulus 3.8 GPa.

(Adhesive treatment solution)
Polymeric MDI: Tosoh Co., Ltd. "Millionate (registered trademark) MR-200", NCO content 30%
NBR Latex: "Nipol (registered trademark) 1562" manufactured by Nippon Zeon Co., Ltd., total solid content 41%, medium-high nitrile type polyolefin adhesive: "Chemloc (registered trademark) 233X" manufactured by Lord, 27% solid content.

(belt)
EPDM: Dow Chemical Japan Ltd. “NORDEL® IP 3640”, ethylene content 55%, ethylidene norbornene content 1.8%
Carbon black HAF: "Siest (registered trademark) 3" manufactured by Tokai Carbon Co., Ltd.
Paraffinic oil: "Diana (registered trademark) process oil" manufactured by Idemitsu Kosan Co., Ltd.
Anti-aging agent: SEIKO CHEMICAL Co., Ltd. "non-flex (registered trademark) OD3"
Organic peroxide: Kayaku Akzo Co., Ltd. "Percadox (registered trademark) 14RP"
Nylon short fiber: "Nylon 66" manufactured by Asahi Kasei Co., Ltd., fiber length about 0.5 mm
Knitted fabric: Weft knitted fabric of cotton yarn and PTT / PET conjugated yarn.

[200 N growth]
It measured based on JISL1017 (2002). Specifically, a single cored wire (made as an adhesion treated cord) was set in a pair of autograph grips so that the cord did not sag straight. The gripping interval at this time was L ₀ (about 250 mm). Next, one grip was moved at a speed of 300 mm / min to apply a tensile load to the cord, and the tensile load and the grip interval were recorded. The elongation at 200 N was determined from the following equation, assuming that the gripping interval at which the tensile load was 200 N was L ₁ (mm).

200 N elongation (%) = ((L _1- L ₀ ) / L ₀ ) × 100

[Bending fatigue test (strength retention)]
As shown in FIG. 2, a single core wire (produced adhesion treated cord) is bent in an S-shape around a pair of cylindrical rotary bars (φ 30 mm) arranged at the top and bottom, and one end of the core wire is framed The other end was loaded with a 1 kg load. Next, the pair of rotary bars reciprocates 100,000 times in the vertical direction (stroke: 140 mm, cycle: 100 times / minute) while keeping the relative distance constant, and winding of the core wire around the rotary bar, Repeated unwinding gave bending fatigue to the core itself. The tensile strength (residual strength) of the cord alone was measured after the bending fatigue test, and the strength retention was calculated from the previously measured tensile strength before the bending fatigue test.

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

[Durable running test (running life)]
The layout is shown in Fig. 3 in which drive pulleys (Dr.) with a diameter of 120 mm, tension pulleys with a diameter of 55 mm (Ten.), Driven pulleys with a diameter of 120 mm (Dn.) And idler pulleys with a diameter of 80 mm (IDL.) I did it using the machine. A V-ribbed belt is hung around each pulley of the tester, the number of rotation of the drive pulley is 4900 rpm, the winding angle of the belt on the idler pulley is 90 °, the winding angle of the belt on the tension pulley is 90 °, and the driven pulley load is 8 A constant load (about 560 N) was applied so that the initial belt tension was 395 N, and the belt was run at an ambient temperature of 100 ° C. until the life of the belt.

Example 1
(Production of twist cord)
As shown in Table 5, a bundle of fibers of 1670 dtex of aramid 1 is pretwisted with a twist coefficient of 1 and three bundles of aliphatic polyamide fibers of 940 dtex with a twist coefficient of 3 lower in the same direction as the aramid fibers. One twisted lower twist yarn was collected and over-twisted with a twist coefficient of 3.5 in the same direction as the first twist to prepare a Lang cord of twisted cord.

(Coding process of cord)
First, the produced twisted cords were immersed for 5 seconds in a treatment liquid (25 ° C.) containing an isocyanate compound shown in Table 1 and then dried at 150 ° C. for 2 minutes (pre-dip treatment step). Next, after immersing the pre-dip treatment twisted cord in RFL treatment liquid (25 ° C.) shown in Table 2 for 5 seconds, heat treatment was performed at 200 ° C. for 2 minutes (RFL treatment step). At the time of this heat treatment, the heat setting was carried out at a heat setting draw ratio of 0 to 3%. Furthermore, after immersing the twisted cords that have undergone RFL treatment for 5 seconds in a treatment solution (solids concentration 7%, 25 ° C.) containing the adhesive component shown in Table 3, dry at 160 ° C. for 4 minutes (overcoat treatment process ), Obtained adhesion treatment code.

(Manufacturing of belts)
A step of forming a first unvulcanized sleeve in which an unvulcanized compressed rubber sheet having a composition shown in Table 4 and a knitted fabric are arranged in this order from the inner circumferential side to an inner mold equipped with a plastic jacket Forming a preform on the surface of the first unvulcanized sleeve by pressing the first unvulcanized sleeve from the inner circumferential side to an outer mold having a rib-shaped impression to form a preform having the rib shape engraved on the surface; After separating the inner mold equipped with the plastic jacket from the outer mold to which the body is in close contact, the unvulcanized stretch rubber sheet having the composition shown in Table 4 and the adhesion treated cord are sequentially arranged on the inner mold fitted with the plastic jacket. Forming the second unvulcanized sleeve, and further expanding the plastic jacket again to press the second unvulcanized sleeve from the inner peripheral side to the outer mold to which the preform is closely attached to be integral with the preform Vulcanizing process After it, to obtain a vulcanized sleeve having a rib shape on the surface. The vulcanized sleeve was cut parallel to the circumferential direction by a cutter to obtain a V-ribbed belt (belt size: 3PK1100, rib shape K shape, 3 ribs, circumferential length 1100 mm).

Example 2
A V-ribbed belt was produced in the same manner as in Example 1 except that the twist factor of the upper twist was changed to 4 in the production of the twist cord.

Example 3
A V-ribbed belt was produced in the same manner as in Example 1 except that the twist factor of the upper twist was changed to 4.5 in the production of the twist cord.

Example 4
In preparation of the twist cord, three lower twist yarns obtained by twisting a bundle of 1100 dtex aramid 2 fibers with a twist coefficient of 0.5 and a bundle of aliphatic polyamide fibers of 940 dtex with a twist coefficient of 0.5 are the same as the aramid fibers A V-ribbed belt was produced in the same manner as in Example 1 except that one lower twisted yarn twisted in the direction was collected and twisted in the same direction as the first twist with a twisting factor of 3 to prepare a Lang cord of twisted yarn.

Example 5
A V-ribbed belt was produced in the same manner as in Example 4 except that the twist factor of the upper twist was changed to 3.5 in the production of the twist cord.

Example 6
A V-ribbed belt was produced in the same manner as in Example 4 except that the twist factor of the upper twist was changed to 4 in the production of the twist cord.

Example 7
In preparation of the twist cord, three lower twist yarns obtained by twisting a bundle of 1100 dtex aramid 2 fibers with a twist coefficient of 3.5 and a bundle of aliphatic polyamide fibers of 940 dtex are equal to aramid fibers with a twist coefficient of 0.5. A V-ribbed belt was produced in the same manner as in Example 1 except that one lower twist yarn twisted in the direction was collected, and was overtwisted with a twist coefficient of 3 in the opposite direction to the first twist to produce a twist cord of multiple twist.

Example 8
A V-ribbed belt was produced in the same manner as in Example 7 except that in the production of the twisted cord, the lower twist coefficient of the aramid fiber 2 was changed to 4.

Example 9
A V-ribbed belt was produced in the same manner as in Example 8 except that in the production of the twist cord, the upper twist coefficient was changed to 3.5.

Example 10
A V-ribbed belt was produced in the same manner as in Example 6 except that the bundle of fibers of aramid 2 was subjected to the top twist without adding the first twist to the production of the twist cord.

Example 11
A V-ribbed belt was produced in the same manner as in Example 6 except that the twist factor of the upper twist was changed to 4.5 in the production of the twist cord.

Example 12
A V-ribbed belt was produced in the same manner as in Example 4 except that in the production of the twisted cords, the first twist coefficient of the aramid 2 fiber bundle and the aliphatic polyamide fiber bundle was changed to 1.5.

Example 13
A V-ribbed belt was produced in the same manner as in Example 9 except that the first twist coefficient of the bundle of aramid 2 fibers was changed to 6.5 and the upper twist coefficient was changed to 6.5 in the production of the twisted cord.

Comparative Example 1
In preparation of the twist cord, three lower twist yarns obtained by twisting a bundle of 1100 dtex aramid 3 fibers with a twist coefficient of 1 and a bundle of aliphatic polyamide fibers of 940 dtex with a twist coefficient of 3 in the same direction as the aramid fibers A V-ribbed belt was produced in the same manner as in Example 1 except that one of the lower twist yarns was collected and overtwisted with a twist coefficient of 2.5 in the opposite direction to the first twist to prepare a twist cord of multiple twist.

Comparative example 2
A V-ribbed belt was produced in the same manner as in Comparative Example 1 except that the upper twist coefficient was changed to 3.5 in the production of the twisted cord.

Comparative example 3
A V-ribbed belt was produced in the same manner as in Comparative Example 1 except that the upper twist coefficient was changed to 4 in the production of the twist cord.

The evaluation results of the adhesion-treated cord and V-ribbed belt obtained in Examples 1 to 13 and Comparative Examples 1 to 3 are shown in Tables 5 to 7.

[Results and Discussion]
As is clear from the results of Tables 5 to 7, Comparative Examples 1 to 3 using aramid 3 having a small intermediate elongation as aramid fibers have a small elongation at 200 N of less than 2.0 with respect to cord physical properties, and show bending fatigue test. The strength retention rate was also less than 75%. Also, with regard to the belt physical properties, the running life was short, less than 200 hours. The reason for the short running life is that if the adhesion treated cords have a small elongation, the resistance when rubber passes through between cords at the time of belt manufacturing (at the time of vulcanization) becomes large, and the position of some cords is shifted , It can be estimated that the pitch of the core wire is disturbed. That is, it can be estimated that the distribution of tension of the belt becomes uneven due to the disturbance of the pitch of the cords, and it becomes easy to cut the filaments in the cords to which a large tension is applied.

On the other hand, in Examples 1 to 13 using aramids 1 and 2 having a large intermediate elongation, the strength retention rate in the bending fatigue test was high at 75% or more for cord physical properties, and the running life was long for 200 hours or longer for belt physical properties . Among them, Examples 4 to 13 using the aramid 2 having the largest intermediate elongation among the aramid fibers used this time had a particularly long running life.

Further, among the examples 4 to 13, since the twist coefficient is adjusted to an appropriate range, the running life of the examples 4 to 9 is long. In Example 10, when the first twist of the aramid fiber is set to 0, the bending fatigue resistance is reduced in Examples 10 compared with Examples 4 to 6 compared with Examples 4 to 6 in comparison with Examples using Lang-twisted twisted cords. Rate and running life decreased. In Example 11, when the ratio of the upper twist coefficient to the first twist coefficient is 9, the running life is reduced as compared with Examples 4 to 6. In Example 12, when the ratio of the upper twist coefficient to the first twist coefficient is 2, the running life is reduced as compared with Examples 4 to 6. In Example 13, when the first twist coefficient and the upper twist coefficient were 6.5, the strength retention and the running life were reduced as compared with Examples 7-9.

Furthermore, focusing on the twisting method, rung twist tended to have a longer running life than plied twist. Further, among the examples using Lang-twisted twisted cords, the relationship between the ratio of the upper twist coefficient to the upper twist coefficient of the aramid fiber and the running life of the V-ribbed belt in Examples 1-6 and 11-12 is shown in FIG. Shown in. As apparent from FIG. 4, in Lang-twist, when the ratio of the upper twist coefficient to the first twist coefficient of the aramid fiber is large, the running life tends to be relatively long, and the ratio is 4 to 8 (especially 5 to 7) It was good in the range of about. In addition, it can be clearly seen that the working life of the embodiment using aramid 2 is relatively longer than that of the embodiment using aramid 1.

The V-ribbed belt of the present invention can be used as a V-ribbed belt used to drive an accessory of an automobile engine, but it can suppress the pitch distortion and damage of the core at the time of manufacturing by a molding method and has high dynamic tension Even if it is used, it is excellent in sound resistance and durability, so it can be particularly suitably used as a V-ribbed belt for driving an ISG-mounted engine that generates high dynamic tension.

Although the invention has been described in detail and with reference to specific embodiments, it will be apparent to those skilled in the art that various modifications and variations can be made without departing from the spirit and scope of the invention.
This application is based on Japanese Patent Application 2017-120811 filed on June 20, 2017 and Japanese Patent Application No. 2018-112540 filed on June 13, 2018, the contents of which are incorporated herein by reference. Taken as

DESCRIPTION OF SYMBOLS 1 ... Core wire 2 .... Compression rubber layer 3 ... V rib part 4 ... Bonding rubber layer 5 ... Stretch layer

Claims

High elongation aramid fiber having an intermediate elongation of 0.8% or more at 4 cN / dtex load and a tensile modulus of 50 to 100 GPa, and a low modulus with a tensile modulus lower than that of the high elongation aramid fiber V-ribbed belt containing twisted cords mixed with fibers.
The V-ribbed belt according to claim 1, wherein the low modulus fiber has a tensile modulus of 20 GPa or less.
The V-ribbed belt according to claim 1 or 2, wherein the proportion of the high elongation aramid fiber is 60 to 95% by mass in the twisted cord.
The twist cord is a twist cord obtained by twisting a plurality of first twist yarns or a twist cord obtained by twisting a plurality of non-twist yarns, the first twist coefficient of this twist cord is 0 to 6, and the upper twist coefficient is 2 to 6 The V-ribbed belt according to any one of claims 1 to 3, which is
The V-ribbed belt according to any one of claims 1 to 4, wherein the twist cord is a rung twist.
The V-ribbed belt according to claim 5, wherein the ratio of the upper twist coefficient to the first twist coefficient of the high elongation aramid fiber is 4 to 8.
The V-ribbed belt according to claim 5 or 6, wherein the ratio of the upper twist coefficient to the first twist coefficient of the high elongation aramid fiber is 5 to 7.
The V-ribbed belt according to any one of claims 5 to 7, which has a lower twist coefficient of 1 or less for high elongation aramid fibers.
The V-ribbed belt according to any one of claims 1 to 4, wherein the twist cords are multi-twist and the high twist aramid fiber has a pretwist coefficient of 2 or more.
The V-ribbed belt according to any one of claims 1 to 9, wherein at least a part of the friction transmission surface is coated with a fabric.
The V-ribbed belt according to any one of claims 1 to 10 mounted on an engine equipped with a belt type ISG drive.
The method for producing a V-ribbed belt according to any one of claims 1 to 11, further comprising a cord preparation step of preparing a cord by bonding the twisted cords, wherein the adhesion processing is performed in the cord preparation step. The heat setting method is a method of heat stretching and fixing at a heat set stretching ratio of 3% or less at the time of heat treatment of.