Toothed belt, method for manufacturing the same, and treatment agent

Abstract

The present invention provides a toothed belt with a simple structure that does not compromise strength or cost-effectiveness, a treatment agent for manufacturing the tooth fabric of a toothed belt, and a method for manufacturing a toothed belt. [Solution] A toothed belt is manufactured through a first processing step in which a cloth to be used as a tooth cloth precursor is treated with a first processing agent to obtain a first precursor. The first processing agent is a mixture containing a first RFL liquid containing a first RFL component consisting of resorcinol, formaldehyde, and latex, and a first conductive dispersion containing a first conductive carbon black, wherein the solid content of the first RFL component in the mixture is 10% by mass or more, and the solid content of the first conductive dispersion is 4 to 10% by mass.

Description

[Technical Field]

[0001] The present invention relates to a toothed belt with conductivity, a method for manufacturing the same, and a treatment agent used in the said manufacturing method. [Background technology]

[0002] Power transmission belts are broadly classified into friction belts and meshing belts. Examples of friction belts include flat belts, V-belts, and V-ribbed belts, while examples of meshing belts include toothed belts. A toothed belt has a back portion with a core wire embedded approximately parallel to the belt's circumference, teeth arranged at predetermined intervals in the belt's circumference, and a toothed fabric covering the surface of the teeth. The teeth of a toothed belt transmit power by engaging with a pulley that has grooves opposite to the teeth. Toothed belts are increasingly being used in industrial machinery, internal combustion engines of automobiles, and rear-wheel drive systems of motorcycles, taking advantage of their characteristic of not causing slippage between the pulley and the belt and being able to reliably transmit power even under high loads.

[0003] Conventional toothed belts are not conductive, and static electricity can build up during use due to repeated contact and separation between the toothed belt and the pulley. This accumulated static electricity can cause sparks (electrical discharges), potentially damaging electronic equipment or leading to ignition or explosion. Therefore, conductivity is required for toothed belts depending on the application. If the toothed belt is conductive, static electricity is slowly discharged to the outside through the pulley, preventing the generation of sparks.

[0004] Japanese Patent Publication No. 2017-512957 (Patent Document 1) discloses a conductive belt that maintains conductivity over a long service life in a harsh load environment, comprising an elastomer belt body, conductive tensile cords in a cord layer reinforcing the belt body, an outer layer of a conductive thermoplastic material, and a conductive canvas layer located between the tensile cord layer and the outer layer, providing electrical continuity between the outer layer and the tensile cords. The document states that, as an alternative to conductive canvas, conductivity may be imparted to non-conductive canvas by conductive RFL immersion treatment, but in the embodiment, a woven fabric containing conductive fibers is used as the conductive canvas layer. [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Special Publication No. 2017-512957 [Overview of the project] [Problems that the invention aims to solve]

[0006] However, in Patent Document 1, the conductive path is secured by constructing the entire transmission belt with conductive materials, which reduces strength and cost-effectiveness compared to transmission belts made of non-conductive materials. In particular, when a woven fabric containing conductive fibers is used as the conductive canvas, there is a drawback that conductivity is lost relatively quickly, possibly due to the small contact area between the conductive fibers and the pulley. Furthermore, on the inner surface of the belt, an outer layer made of a conductive thermoplastic material is laminated on the surface of such conductive canvas, resulting in a complex layer structure.

[0007] Therefore, the object of the present invention is to provide a toothed belt with a simple structure that is imparted with conductivity (antistatic properties) without reducing strength and cost-effectiveness, a method for manufacturing the same, and a treatment agent used in the said manufacturing method.

[0008] Another object of the present invention is to provide a toothed belt that can maintain conductivity even after prolonged driving, a method for manufacturing the same, and a treatment agent used in the said manufacturing method. [Means for solving the problem]

[0009] To achieve the above objectives, the present inventors discovered that by treating a fabric with a treatment agent comprising a resorcinol-formaldehyde-latex solution (RFL solution) and a conductive carbon black dispersion in specific proportions, it is possible to provide a toothed belt with a simple structure that is conductive without reducing strength or cost-effectiveness, thus completing the present invention.

[0010] In other words, the present invention includes the following embodiments.

[0011] Embodiment [1]: A treatment agent for manufacturing tooth fabric for a toothed belt, A mixture comprising a first RFL solution containing a first RFL component consisting of resorcinol, formaldehyde, and latex, and a first conductive dispersion containing a first conductive carbon black, A first treatment agent wherein the solid content of the first RFL component in the mixed liquid is 10% by mass or more, and the solid content of the first conductive dispersion is 4 to 10% by mass.

[0012] Embodiment [2]: The first treatment agent according to Embodiment [1], wherein the proportion of solids in the mixed liquid is 4.5 to 8% by mass of the first conductive dispersion.

[0013] Embodiment [3]: The first treatment agent according to Embodiment [1] or [2], wherein the proportion of solids of the first RFL component in the mixed liquid is 13% by mass or more.

[0014] Embodiment [4]: ​​A method for manufacturing a toothed belt, comprising a first processing step of processing a cloth as a tooth cloth precursor with a first processing agent described in any of Embodiments [1] to [3] to obtain a first precursor.

[0015] Aspect [5]: The manufacturing method according to aspect [4], further comprising a second treatment step of treating the first precursor with a second treatment agent containing a second RFL component composed of resorcinol, formaldehyde, and latex to obtain a second precursor.

[0016] Aspect [6]: The manufacturing method according to aspect [5], wherein the second treatment agent does not contain conductive carbon black.

[0017] Aspect [7]: The second treatment agent is a mixed liquid containing a second RFL liquid containing a second RFL component composed of resorcinol, formaldehyde, and latex and a second conductive dispersion liquid containing a second conductive carbon black, and the solid content ratio of the second conductive dispersion liquid in the second treatment agent is less than the solid content ratio of the first conductive dispersion liquid in the first treatment agent. The manufacturing method according to aspect [5] or [6].

[0018] Aspect [8]: The manufacturing method according to any one of aspects [5] to [7], wherein the solid content ratio of the second RFL component in the second treatment agent is equal to or more than the solid content ratio of the first RFL component in the first treatment agent.

[0019] Aspect [9]: The manufacturing method according to any one of aspects [5] to [8], wherein the second treatment agent further contains a maleimide compound.

[0020] Aspect

[10] : A toothed belt obtained by the manufacturing method according to any one of aspects [4] to [9].

[0021] Aspect

[11] : A back portion in which a core wire extending along the belt circumferential direction is embedded, On the inner peripheral surface of the back portion, a plurality of tooth portions formed at intervals in the belt circumferential direction, Including a back rubber layer formed on the outer peripheral side of the belt with respect to the core wire and a tooth rubber layer formed on the inner peripheral side of the belt with respect to the core wire, and A toothed belt in which the inner peripheral surface of the belt is composed of a tooth cloth, The tooth cloth is composed of a cloth and an impregnating component impregnated in the cloth, The aforementioned impregnation component is a toothed belt containing conductive carbon black.

[0022] Embodiment

[12] : The toothed belt according to Embodiment

[10] or

[11] , wherein the conductive carbon black is conductive carbon black derived from a conductive dispersion containing conductive carbon black, and the proportion of solids in the conductive dispersion is 0.1 to 10 parts by mass per 100 parts by mass of the cloth.

[0023] Embodiment

[13] : A toothed belt according to any of Embodiments

[10] to

[12] , wherein the back portion and the tooth rubber layer do not contain conductive additives.

[0024] Appearance

[14] : The electrical resistance R of the belt tooth surface measured by a method compliant with ISO9563(2015) is 6 × 10 5 A toothed belt according to any of the above embodiments

[10] to

[13] , wherein the value is less than or equal to ×L / W(Ω) [where L is the distance between electrodes (mm) and W is the width of the electrodes (mm) (however, if the width of the belt is smaller than the width of the electrodes, the width of the belt)].

[0025] In this application, "solid content" refers to components excluding solvents such as water, and in the case of conductive dispersions and RFL components, it refers to components that do not volatilize and remain on the tooth fabric of the toothed belt. [Effects of the Invention]

[0026] In this invention, the fabric is treated with a treatment agent that combines RFL liquid and conductive carbon black dispersion in a specific ratio. This allows for the provision of a toothed belt with conductivity without compromising strength or cost-effectiveness, thanks to its simple structure. In particular, the conductive carbon black penetrates and disperses throughout the interior of the toothed fabric, maintaining conductivity even if the fabric is slightly worn. Therefore, conductivity can be maintained even after long periods of use until the belt reaches the end of its lifespan. [Brief explanation of the drawing]

[0027] [Figure 1] Figure 1 is a schematic partial cross-sectional perspective view showing an example of a toothed belt according to the present invention. [Figure 2] Figure 2 is a schematic cross-sectional view of the toothed belt shown in Figure 1. [Figure 3] Figure 3 is a schematic diagram illustrating the method for measuring the electrical resistance of the toothed belt obtained in the embodiment. [Figure 4] Figure 4 shows the layout for the durability running test of the toothed belt obtained in the embodiment. [Modes for carrying out the invention]

[0028] The present invention provides a method for manufacturing a toothed belt, comprising a first processing step of treating a cloth as a tooth cloth precursor with a first processing agent to obtain a first precursor, and further comprising a second processing step of treating the first precursor with a second processing agent preferably containing RFL liquid to obtain a second precursor.

[0029] [First Processing Step] The first treatment agent used in the first treatment step is a mixture containing an RFL solution (first RFL solution) containing an RFL component (first RFL component) consisting of resorcinol, formaldehyde, and latex, and a conductive dispersion (first conductive dispersion) containing conductive carbon black (first conductive carbon black).

[0030] (1st RFL liquid) The first RFL solution contains an RFL component consisting of resorcinol (R), formaldehyde (F), and latex (L). In the first RFL component, resorcinol (R) and formaldehyde (F) may be included in the form of their condensate (first RF condensate). The first RF condensate has excellent compatibility with latex and can form a flexible film.

[0031] The first RF condensate is not particularly limited, and examples include novolac type, resol type, and combinations thereof. A combination (mixture) of novolac type and resol type is preferred as the first RF condensate because it can form a film on the surface of the first treatment agent.

[0032] The first RF condensate may be, for example, a reaction product (e.g., an initial condensate or prepolymer) obtained by reacting resorcinol with formaldehyde in the presence of water and a base catalyst (alkali metal salts such as sodium hydroxide; alkaline earth metal salts; ammonia, etc.). Furthermore, as long as it does not hinder the effects of the present invention, aromatic monools such as phenol and cresol may be used in combination with resorcinol, or aromatic di or polyols such as catechol and hydroquinone. Also, as formaldehyde, formaldehyde condensates (e.g., trioxane, paraformaldehyde, etc.) or aqueous solutions of formaldehyde (formalin, etc.) may be used.

[0033] In the first RF condensate, the ratio (usage ratio) of resorcinol to formaldehyde can be selected from a range of approximately 1 / 0.1 to 1 / 5, for example, in terms of the molar ratio of the former / latter = 1 / 0.3 to 1 / 3, preferably 1 / 0.5 to 1 / 2, more preferably 1 / 0.7 to 1 / 1.5, more preferably 1 / 0.8 to 1 / 1.2, and most preferably 1 / 0.9 to 1 / 1.1. If the proportion of formaldehyde is too high, there is a risk of contamination by residual formaldehyde, and conversely, if it is too low, there is a risk of the strength of the coating decreasing.

[0034] The rubber constituting the latex (first latex) is not particularly limited and includes, for example, diene rubbers [e.g., natural rubber, isoprene rubber, butadiene rubber, chloroprene rubber (CR latex), styrene-butadiene rubber (SBR latex), vinylpyridine-styrene-butadiene copolymer rubber (VP latex), acrylonitrile butadiene rubber (nitrile rubber or NBR latex), hydrogenated versions of these diene rubbers, etc.], olefin rubbers [e.g., ethylene-α-olefin rubber (ethylene-α-olefin elastomer), polyoctenylene rubber, ethylene-vinyl acetate copolymer rubber, chloroprene rubber, chlorosulfonated polyethylene rubber, alkylated chlorosulfonated polyethylene rubber, etc.], acrylic rubbers, silicone rubbers, urethane rubbers, epichlorohydrin rubbers, fluororubbers, etc. These rubbers can be used individually or in combination of two or more types.

[0035] Of these rubbers, the same or similar type of rubber used to embed the core wire is preferred, and diene-based rubbers such as hydrogenated nitrile rubber (H-NBR latex), vinylpyridine-styrene-butadiene copolymer rubber (VP latex), and chloroprene rubber (CR latex) are particularly preferred.

[0036] The proportion of the first latex (rubber) is, for example, 40 to 2500 parts by mass, preferably 50 to 2000 parts by mass, more preferably 100 to 1500 parts by mass, more preferably 200 to 1000 parts by mass, and most preferably 300 to 500 parts by mass in terms of solid content, per 100 parts by mass of the first RF condensate. If the proportion of the first latex is too low, the flexibility of the coating may decrease, and conversely, if it is too high, the strength of the coating may decrease.

[0037] The first RFL solution may contain multiple types of RFL components; for example, each type may be separated into liquid and mixed together when mixing with the conductive dispersion.

[0038] In this invention, the proportion of the first RFL component in the first treatment agent is adjusted in order to improve the durability of the toothed belt. The proportion of solids of the first RFL component is 10% by mass or more (particularly 13% by mass or more) in the first treatment agent (mixture), for example, 10 to 50% by mass, preferably 12 to 30% by mass, more preferably 13 to 25% by mass, more preferably 14 to 20% by mass, and most preferably 15 to 18% by mass. If the proportion of solids of the first RFL component is too low, not only will the adhesion of the tooth cloth decrease, but the wear resistance will also decrease, resulting in a decrease in durability and conductivity retention.

[0039] The solid content of the first RFL component is 15% by mass or more in the first RFL liquid, for example, 15-50% by mass, preferably 18-40% by mass, and more preferably 20-30% by mass.

[0040] The RFL solution preferably contains a hydrophilic solvent. Examples of hydrophilic solvents include water and lower aliphatic alcohols (e.g., ethanol, isopropanol, etc.). 1-4 Examples include alkyl alcohols, alkylene glycols (e.g., ethylene glycol, diethylene glycol, propylene glycol, etc.), and ketones (e.g., acetone, etc.). These hydrophilic solvents can be used alone or in combination of two or more. Of these, hydrophilic solvents containing water are preferred, and water alone is particularly preferred.

[0041] The first RFL solution may contain conventional additives. Examples of conventional additives include crosslinking agents, crosslinking promoters, co-crosslinking agents, adhesion improvers, dispersants, fillers, anti-aging agents, and lubricants. These additives can be used individually or in combination of two or more. The proportion of conventional additives is, for example, 10 parts by mass or less, preferably 5 parts by mass or less, and more preferably 1 part by mass or less, per 100 parts by mass of the first RFL component. The first RFL solution may not contain conventional additives.

[0042] The total solid content concentration of the first RFL solution (the concentration obtained by dividing the total mass of the solid content of the RFL components and the solid content of the conventional additives by the mass of the RFL solution) is, for example, 15 to 50% by mass, preferably 18 to 40% by mass, and more preferably 20 to 30% by mass.

[0043] (Conductive dispersion) The conductive dispersion (first conductive dispersion) contains conductive carbon black (first conductive carbon black). In this invention, the conductivity of the tooth cloth can be improved by including the first conductive carbon black in the first conductive dispersion. Even with ordinary non-conductive carbon black, high conductivity can be imparted if a large amount is added, but the adhesion to the cloth decreases. In contrast, by using conductive carbon black, conductivity can be imparted with a small amount, so conductivity can be imparted to the cloth while maintaining adhesion to the cloth.

[0044] The average primary particle size of the first conductive carbon black is, for example, 1 to 100 nm, preferably 1 to 50 nm, more preferably 3 to 40 nm, and more preferably 5 to 30 nm. If the average primary particle size of the conductive carbon black is too small, the dispersibility of the conductive carbon black in the first treatment agent may decrease, and conversely, if it is too large, the conductivity of the tooth cloth may decrease.

[0045] In this application, the average primary particle diameter of conductive carbon black can be calculated as the arithmetic mean particle diameter of an appropriate number of samples (e.g., 50 samples) by image analysis of electron microscope photographs, including those taken with a transmission electron microscope.

[0046] The DBP absorption rate of the first conductive carbon black may be 100 mL / 100 g or more (particularly 300 mL / 100 g or more), for example, 100 to 600 mL / 100 g, preferably 300 to 550 mL / 100 g, and more preferably 350 to 500 mL / 100 g. If the DBP absorption rate is too low, there is a risk that the conductivity of the tooth cloth will decrease.

[0047] In this application, the DBP absorption amount of the first conductive carbon black refers to the value (OAN) that can be measured for an uncompressible sample, in accordance with JIS K 6217-4 (2017).

[0048] The BET specific surface area of ​​conductive carbon black is 300 m². 2 / g or more (especially 500m 2 It may also be 300-2000m (or more / g), for example 2 / g, preferably 500-1500m 2 / g, more preferably 700-1300m 2 It is / g. If the BET specific surface area is too small, there is a risk that the conductivity of the tooth cloth will decrease.

[0049] In this application, BET specific surface area refers to the specific surface area measured using nitrogen gas by the BET method.

[0050] Examples of first conductive carbon blacks include thermal black, Ketjen black, acetylene black, channel black, and color black.

[0051] The first conductive dispersion may further contain a filler, provided that it does not impair the effects of the present invention. Preferred fillers include non-conductive carbon black such as furnace black. The proportion of the filler is 100 parts by mass or less, preferably 50 parts by mass or less, and more preferably 10 parts by mass or less, per 100 parts by mass of the first conductive carbon black. The first conductive dispersion preferably contains substantially no non-conductive carbon black, and is particularly preferably free of it.

[0052] The first conductive dispersion may contain conventional additives. Examples of conventional additives include crosslinking agents, crosslinking promoters, co-crosslinking agents, adhesion improvers, dispersants, antioxidants, and lubricants. These additives can be used individually or in combination of two or more. Of these, dispersants are preferred.

[0053] The proportion of the commonly used additive is, for example, 0.1 to 100 parts by mass, preferably 0.5 to 80 parts by mass, and more preferably 1 to 50 parts by mass, per 100 parts by mass of the first conductive carbon black.

[0054] In this invention, the proportion of solids in the first conductive dispersion in the first treatment agent (total solids concentration) is adjusted in order to improve the conductivity of the tooth cloth. The proportion of solids in the first conductive dispersion is 4 to 10% by mass in the first treatment agent (mixture), preferably 4.5 to 8% by mass, more preferably 4.5 to 7% by mass, more preferably 4.5 to 6% by mass, and most preferably 4.5 to 5.5% by mass. If the proportion of solids in the first conductive dispersion is too low, the conductivity of the tooth cloth decreases, and conversely, if it is too high, the adhesion to the tooth cloth decreases.

[0055] The first conductive dispersion preferably contains a hydrophilic solvent. Examples of hydrophilic solvents include those exemplified as hydrophilic solvents for the RFL solution. The hydrophilic solvent can be used alone or in combination of two or more. Among the hydrophilic solvents, a hydrophilic solvent containing water is preferred, and water alone is particularly preferred.

[0056] The proportion of the first conductive carbon black may be 10% by mass or more, preferably 30% by mass or more, and more preferably 50% by mass or more, in the solid content of the first conductive dispersion, for example, 10 to 99% by mass, preferably 30 to 95% by mass, and more preferably 50 to 90% by mass.

[0057] The first conductive dispersion may contain multiple types of conductive carbon black; for example, each type may be separated into liquid and mixed when mixing with the RFL solution.

[0058] The total solid content concentration of the first conductive dispersion is, for example, 3 to 50% by mass, preferably 5 to 30% by mass, and more preferably 10 to 20% by mass.

[0059] (Characteristics of the first treatment agent) The first treatment agent may be a mixed solution containing the first RFL liquid and the first conductive dispersion liquid, and may further contain a solution and / or a dispersion liquid containing other functional components, etc. However, from the perspective of simplicity, etc., a mixed solution of the first RFL liquid and the first conductive dispersion liquid is preferred.

[0060] The first RFL liquid and the first conductive dispersion liquid may be mixed such that the solid content ratio of the first RFL component is 10% by mass or more, and the solid content ratio of the first conductive dispersion liquid is 4 to 10% by mass.

[0061] The total solid content concentration of the first treatment agent is, for example, 1 to 50% by mass, preferably 5 to 40% by mass, more preferably 10 to 30% by mass, still more preferably 12 to 20% by mass, and most preferably 13 to 18% by mass.

[0062] (Fabric) The fabric (fabric or cloth) as the fabric precursor may be, for example, a woven fabric, a knitted fabric, a non-woven fabric, etc. Conventionally, it is often a woven fabric (canvas), and is composed of a woven fabric formed by weaving warp threads extending in the belt width direction and weft threads extending in the belt circumferential direction. The weave of the woven fabric is not particularly limited as long as the warp threads and the weft threads cross regularly in the vertical and horizontal directions, and may be any of plain weave, twill weave (or diagonal weave), satin weave (satin, satin), etc., or a weave combining these weaves. Preferred woven fabrics have twill weave and satin weave structures.

[0063] Examples of the fibers forming the fabric include polyolefin fibers (such as polyethylene fibers, polypropylene fibers, etc.), polyamide fibers [aliphatic polyamide fibers (nylon fibers) such as polyamide 6 fibers, polyamide 66 fibers, polyamide 46 fibers, aramid fibers, etc.], polyester fibers [polyalkylene arylate fibers (for example, polyethylene terephthalate (PET) fibers, polytrimethylene terephthalate (PTT) fibers, polybutylene terephthalate (PBT) fibers, polyethylene naphthalate (PEN) fibers, etc.) of C 2-4 alkylene C 8-14Examples of synthetic fibers include: arylate fibers; polyarylate fibers, fully aromatic polyester fibers such as liquid crystal polyester fibers, etc.; vinylon fibers, polyvinyl alcohol fibers, poly(p-phenylenebenzobisoxazole) (PBO) fibers, polyphenylene ether fibers, polyether ether ketone fibers, polyether sulfone fibers, polyurethane fibers, etc.; natural fibers such as cotton, linen, and wool; regenerated cellulose fibers such as rayon; cellulose ester fibers, etc.; and inorganic fibers such as carbon fibers and glass fibers. These fibers can be used individually or in combination of two or more types.

[0064] Of these fibers, organic fibers are commonly used, with cellulose fibers such as cotton and rayon, polyester fibers (such as PET fibers), polyamide fibers (such as aliphatic polyamide fibers like polyamide 66 fibers, aramid fibers, etc.), PBO fibers, and fluororesin fibers [such as polytetrafluoroethylene (PTFE) fibers] being preferred. Composite yarns of these fibers with elastic yarns that have elasticity (for example, polyurethane-based elastic yarns that have elasticity, such as spandex made of polyurethane, and processed yarns that have undergone stretch processing (for example, woolly processing, crimping processing, etc.)) are also preferred.

[0065] If the fabric is woven, the form of the warp and weft threads is not particularly limited and may be monofilament yarn, which is a single long fiber; multifilament yarn, which is made by aligning or twisting filaments (long fibers); or spun yarn, which is made by twisting short fibers. The multifilament yarn or spun yarn may be a blended yarn or blended yarn using multiple types of fibers. The weft threads preferably contain elastic yarn, while the warp threads usually do not contain elastic yarn from the viewpoint of weaving. In order to ensure the elasticity of the tooth fabric in the circumferential direction of the belt, the weft threads containing elastic yarn extend in the circumferential direction of the belt, and the warp threads extend in the width direction of the belt.

[0066] The average diameter of the fibers is, for example, 1 to 100 μm (e.g., 3 to 50 μm), preferably 5 to 30 μm, and more preferably 7 to 25 μm. Regarding the average fiber diameter (thickness) of the yarn (twisted yarn), the weft may be, for example, around 100 to 1000 dtex (particularly 300 to 700 dtex), and the warp may be, for example, around 50 to 500 dtex (particularly 100 to 300 dtex). The density of the weft (threads / cm) may be, for example, around 5 to 50 (particularly 10 to 30), and the density of the warp (threads / cm) may be, for example, around 10 to 300 (particularly 20 to 100).

[0067] The woven fabric may have a multi-layered structure (such as a double-layered structure), and in a woven structure comprising warp and weft threads, at least some of the weft threads may be made of low-friction fibers (or low-friction fibers) such as fluororesin-containing fibers (such as composite yarns containing fibers formed from fluororesins such as PTFE). For example, the warp threads may be made of polyamide fibers such as nylon 66, polyester fibers, etc., and the weft threads may be made of fluororesin-formed fibers alone; composite yarns of fluororesin-formed fibers and second fibers such as polyamide fibers or polyurethane fibers (elastic yarns); or composite yarns of this composite yarn and a second composite yarn formed from a plurality of the second fibers.

[0068] In woven fabrics with a multi-layered weave structure, it is preferable to use fluorine-based fibers (e.g., PTFE fibers) with a low coefficient of friction as the weft threads located on the surface side of the toothed fabric (the side that engages with the toothed pulley) (exposed side) in order to reduce friction between the toothed fabric and the toothed pulley. By including fluorine-based fibers, wear of the toothed fabric can be suppressed, and the conductivity of the toothed belt can be maintained even after prolonged operation. On the other hand, by using fibers other than fluorine-based fibers for the weft threads located on the back side of the toothed fabric (the side that adheres to the teeth), it is possible to increase the adhesive strength between the toothed fabric and the rubber constituting the teeth.

[0069] Furthermore, when using fluorine-based fibers, it is preferable that low-melting-point fibers having a melting point that melts at the crosslinking (vulcanization) temperature of the teeth and back, which are based on rubber, are arranged around the fluorine-based fibers. Specifically, the form of the composite yarn containing fluorine-based fibers includes forms in which fluorine-based fibers and low-melting-point fibers are mixed and twisted together, or forms in which fluorine-based fibers are covered by low-melting-point fibers. The crosslinking (vulcanization) conditions of the teeth and back are not particularly limited, but generally, the crosslinking (vulcanization) temperature is 100 to 200°C and the crosslinking (vulcanization) time is 1 minute to 5 hours.

[0070] In an embodiment in which low-melting-point fibers are arranged around fluorine-based fibers, the low-melting-point fibers melt during cross-linking (vulcanization) of the teeth and back portions, flow into the spaces between the fibers constituting the tooth fabric, and then crystallize when cooled to below their melting point. Therefore, the cutting and scattering of fluorine-based fibers due to impact and abrasion on the surface of the tooth fabric during engagement with or disengagement from a toothed pulley is suppressed.

[0071] The average thickness of the tooth fabric (the tooth fabric in the toothed belt) is, for example, 0.1 to 2 mm, preferably 0.2 to 1.5 mm. The average thickness of the tooth fabric as raw material (the tooth fabric before molding) is, for example, 0.5 to 3 mm, preferably 0.75 to 2.5 mm.

[0072] (Processing method) Examples of methods for treating the fabric include immersing the fabric in the first treatment agent and applying the first treatment agent to the fabric. Of these methods, immersing the fabric in the first treatment agent is preferred because it allows the first treatment agent to penetrate uniformly into the fabric.

[0073] The processing temperature is, for example, 0 to 60°C, preferably 5 to 50°C, more preferably 10 to 40°C, and more preferably 15 to 35°C. The processing time is, for example, 1 second to 30 minutes, preferably 2 seconds to 10 minutes, more preferably 3 seconds to 1 minute, and more preferably 4 to 10 seconds.

[0074] The cloth treated with the first treatment agent may be subjected to a drying treatment. The drying treatment may be natural drying, but from the viewpoint of productivity, heating is preferred. The heating temperature is, for example, 60 to 220°C, preferably 100 to 200°C, more preferably 150 to 190°C, and more preferably 160 to 180°C. As a pretreatment before the drying treatment, excess treatment liquid may be removed using a squeezing roll or the like.

[0075] [Second Processing Step] The manufacturing method of the present invention, by including a second processing step in addition to the first processing step, can improve the adhesion between the tooth cloth and the tooth rubber layer, and further improve the wear resistance of the tooth cloth, thereby maintaining the conductivity of the toothed belt even after prolonged use.

[0076] (Second treatment agent) The second treatment agent used in the second treatment step may contain a second RFL component consisting of resorcinol, formaldehyde, and latex.

[0077] In the second RFL component, resorcinol (R) and formaldehyde (F) may be included in the form of their condensate (second RF condensate). The second RF condensate has excellent compatibility with latex and can form a flexible coating.

[0078] The second RF condensate can be selected from the RF condensates exemplified as the first RF condensate, including preferred embodiments.

[0079] In the second RF condensate, the ratio (usage ratio) of resorcinol to formaldehyde can be selected from a range of approximately 1 / 0.1 to 1 / 5, for example, in terms of the molar ratio of the former / latter = 1 / 0.5 to 1 / 3, preferably 1 / 1 to 1 / 2, more preferably 1 / 1.2 to 1 / 1.8, more preferably 1 / 1.3 to 1 / 1.7, and most preferably 1 / 1.4 to 1 / 1.6. If the proportion of formaldehyde is too high, there is a risk of contamination by residual formaldehyde, and conversely, if it is too low, there is a risk of the strength of the coating decreasing.

[0080] The rubber constituting the latex (second latex) can be selected from the rubbers exemplified as the rubber for the first latex, including preferred embodiments.

[0081] The proportion of the second latex (rubber) is, for example, 50 to 2500 parts by mass, preferably 100 to 2000 parts by mass, more preferably 200 to 1500 parts by mass, more preferably 400 to 1200 parts by mass, and most preferably 600 to 1000 parts by mass in terms of solid content, per 100 parts by mass of the second RF condensate. If the proportion of the second latex is too low, the flexibility of the coating may decrease, and conversely, if it is too high, the strength of the coating may decrease.

[0082] In the present invention, the proportion of the second RFL component in the second treatment agent may be adjusted in order to improve the durability of the toothed belt. The proportion of solids of the second RFL component in the second treatment agent may be greater than or equal to the proportion of solids of the first RFL component in the first treatment agent, for example, 0 to 30% by mass higher than the proportion of solids of the first RFL component, preferably 1 to 20% by mass higher, more preferably 3 to 10% by mass higher, and more preferably 4 to 7% by mass higher. Specifically, the proportion of solids of the second RFL component is 10% by mass or more (particularly 15% by mass or more) in the second treatment agent, for example, 10 to 50% by mass, preferably 15 to 30% by mass, more preferably 18 to 25% by mass, and more preferably 20 to 22% by mass. If the proportion of solids of the second RFL component is too low, the wear resistance may decrease.

[0083] The second treatment agent preferably further contains a maleimide compound. The maleimide compound may be a bismaleimide compound.

[0084] Examples of bismaleimide compounds include aliphatic bismaleimides (e.g., N,N'-1,2-ethylenedimaleimide, 1,6'-bismaleimide-(2,2,4-trimethyl)cyclohexane, etc.) and aromatic bismaleimides {e.g., N,N'-m-phenylenedimaleimide, 4-methyl-1,3-phenylenedimaleimide, 4,4'-diphenylmethanedimaleimide, 2,2-bis[4-(4-maleimoidphenoxy)phenyl]propane, 4,4'-diphenyletherdimaleimide, 4,4'-diphenylsulfonedimaleimide, 1,3-bis(3-maleimoidphenoxy)benzene, etc.)}.

[0085] These bismaleimide compounds can be used individually or in combination of two or more. Of these, aromatic bismaleimides (arene bismaleimides), such as N,N'-m-phenylenedimaleimide, are preferred due to their excellent heat resistance.

[0086] The proportion of the maleimide compound is, for example, 1 to 100 parts by mass, preferably 3 to 80 parts by mass, more preferably 5 to 50 parts by mass, more preferably 10 to 30 parts by mass, and most preferably 15 to 25 parts by mass, per 100 parts by mass of the second RFL component. If the proportion of the maleimide compound is too low, the effect of improving the adhesion of the tooth cloth to the tooth rubber layer may not be achieved, and if it is too high, the conductivity may decrease.

[0087] The second treatment agent may further contain a basic compound. Examples of basic compounds include alkali metal hydroxides such as lithium hydroxide, sodium hydroxide, and potassium hydroxide; alkali metal or alkaline earth metal carbonates such as sodium carbonate, sodium bicarbonate, and magnesium carbonate; and ammonia.

[0088] These basic compounds can be used individually or in combination of two or more. Of these, alkali metal hydroxides such as sodium hydroxide are preferred.

[0089] The proportion of the basic compound is, for example, 0.01 to 10 parts by mass, preferably 0.05 to 5 parts by mass, more preferably 0.1 to 3 parts by mass, more preferably 0.2 to 1 part by mass, and most preferably 0.3 to 0.8 parts by mass, per 100 parts by mass of the second RFL component.

[0090] The second treatment agent may further contain conductive carbon black (second conductive carbon black).

[0091] The second conductive carbon black can be selected from the conductive carbon blacks exemplified as the first conductive carbon black, including preferred embodiments. The average primary particle size, DBP absorption amount, and BET specific surface area of ​​the second conductive carbon black can be selected from the average primary particle size, DBP absorption amount, and BET specific surface area of ​​the first conductive carbon black, including preferred ranges.

[0092] The proportion of the second conductive carbon black in the second treatment agent is preferably less than the proportion of the first conductive carbon black in the first treatment agent, in order to improve wear resistance. Furthermore, it is even more preferable that the second treatment agent substantially does not contain the second conductive carbon black, and even more preferable that it does not contain the second conductive carbon black at all.

[0093] If the second treatment agent contains a second conductive carbon black, the second treatment agent may be a mixture containing a second RFL solution containing a second RFL component and a second conductive dispersion containing a second conductive carbon black.

[0094] The second conductive dispersion may further contain a filler. The filler can be selected from the fillers exemplified in the section on the first conductive dispersion, including preferred embodiments. The proportion of the filler can be selected from the proportion in the first conductive dispersion, including a preferred range.

[0095] The second conductive dispersion may further contain conventional additives. These conventional additives can be selected from those exemplified in the section on the first conductive dispersion, including preferred embodiments. The proportion of the conventional additives can be selected from the proportions in the first conductive dispersion, including a preferred range.

[0096] The second conductive dispersion may further contain a hydrophilic solvent. The hydrophilic solvent can be selected from the conventional additives exemplified in the section on the first conductive dispersion, including preferred embodiments.

[0097] The proportion of the second conductive carbon black may be 10% by mass or more (preferably 30% by mass or more, more preferably 50% by mass or more) of the solid content of the second conductive dispersion, for example, 10 to 99% by mass, preferably 30 to 95% by mass, and more preferably 50 to 90% by mass.

[0098] The proportion of solids in the second conductive dispersion in the second treatment agent is preferably less than the proportion of solids in the first conductive dispersion in the first treatment agent. For example, it is 1 to 20% less by mass than the proportion of solids in the first conductive dispersion in the first treatment agent, preferably 2 to 10% less by mass, more preferably 3 to 8% less by mass, and more preferably 4 to 7% less by mass. Specifically, the proportion of solids in the second conductive dispersion may be 10% by mass or less in the second treatment agent, preferably 8% by mass or less, more preferably 5% by mass or less, more preferably 3% by mass or less, and most preferably 1% by mass or less. If the proportion of solids in the second conductive dispersion is too high, the adhesion of the tooth cloth to the tooth rubber layer may decrease, and the abrasion resistance may also decrease.

[0099] (Characteristics of the second treatment agent) The second treatment agent may contain a second RFL component, and may be a second RFL solution containing the second RFL component alone, or a mixture with other solutions and / or dispersions (such as a second conductive dispersion or a solution and / or dispersion containing other functional components). The second RFL solution may contain multiple types of RFL components, and may, for example, be a mixture of each RFL solution separated by type.

[0100] The total solid content concentration of the second treatment agent is, for example, 5 to 50% by mass, preferably 10 to 40% by mass, more preferably 15 to 30% by mass, more preferably 18 to 26% by mass, and most preferably 20 to 23% by mass.

[0101] (Processing method) Examples of methods for treating the first precursor include immersing the first precursor in a second treatment agent and applying the second treatment agent onto the first precursor. Of these treatment methods, immersing the first precursor in a second treatment agent is preferred because it allows the second treatment agent to penetrate uniformly into the interior of the first precursor.

[0102] The processing temperature is, for example, 0 to 60°C, preferably 5 to 50°C, more preferably 10 to 40°C, and more preferably 15 to 35°C. The processing time is, for example, 1 second to 30 minutes, preferably 2 seconds to 10 minutes, more preferably 3 seconds to 1 minute, and more preferably 4 to 10 seconds.

[0103] The second precursor treated with the second treatment agent may be subjected to further drying. The drying process may be carried out by natural drying, but from the viewpoint of productivity, it is preferable to dry by heating. The heating temperature is, for example, 60 to 220°C, preferably 100 to 200°C, more preferably 150 to 190°C, and more preferably 160 to 180°C. As a pretreatment before the drying process, excess treatment liquid may be removed using a squeezing roll or the like.

[0104] The second precursor may be further combined with conventional bonding treatments. Conventional bonding treatments include, for example, treatment with an epoxy compound or isocyanate compound; dissolving a rubber composition in an organic solvent to make a rubber glue, immersing a cloth in this rubber glue, and then heating and drying it; applying a highly viscous rubber glue to one side of the second precursor (the side in contact with the tooth rubber layer) (coating method or spreading method); and laminating a sheet formed from the rubber composition onto one side of the second precursor (the side in contact with the tooth rubber layer).

[0105] [Toothed belt] Since the toothed belt of the present invention is obtained by a manufacturing method including the first processing step, the impregnation component of the fabric constituting the tooth cloth contains conductive carbon black. Therefore, in the tooth cloth of the toothed belt of the present invention, the conductive carbon black is conductive carbon black derived from a conductive dispersion containing conductive carbon black (conductive carbon black derived from a first conductive dispersion, or conductive carbon black derived from both a first and a second conductive dispersion). In the tooth cloth, the proportion of such conductive carbon black (solid content of the conductive dispersion) is, for example, 0.1 to 10 parts by mass, preferably 0.5 to 8 parts by mass, more preferably 1 to 5 parts by mass, more preferably 1.5 to 4 parts by mass, and most preferably 2 to 3 parts by mass per 100 parts by mass of fabric. If the proportion of conductive carbon black is too low, the conductivity may decrease, and if it is too high, the adhesion of the tooth cloth to the tooth rubber layer may decrease, and the wear resistance may also decrease.

[0106] Below, an example of a toothed belt of the present invention will be described in detail, with reference to the attached drawings as necessary. In the following description, elements (or components) that are the same or have common functions may be denoted by the same reference numeral.

[0107] Figure 1 is a schematic partial cross-sectional perspective view showing an example of a toothed belt of the present invention, and Figure 2 is a schematic cross-sectional view of the toothed belt of Figure 1. The toothed belt 1 in this example is an endless interlocking transmission belt, and comprises a back portion 1c in which a core wire 4 extending in the belt circumferential direction (longitudinal direction) is embedded, and a plurality of teeth 1a provided at predetermined intervals in the circumferential direction and extending in the belt width direction on the inner surface of the back portion 1c, and the belt surface (inner surface) on the tooth side is made of tooth fabric 2. The back portion 1c has a back rubber layer 5 disposed on the belt outer surface side of the core wire 4, and this back rubber layer 5 forms the belt outer surface. Furthermore, the toothed belt 1 has a tooth rubber layer (rubber layer forming the teeth) 3 between the tooth fabric 2 and the core wire 4 on the belt inner surface side of the core wire 4.

[0108] Between adjacent tooth portions 1a, there is a flat tooth root portion 1b, and the tooth portions 1a and tooth root portions 1b are alternately formed along the circumferential direction (belt longitudinal direction) on the inner surface of the belt. That is, the surface of the tooth portion 1a and the inner surface of the back portion 1c (i.e., the surface of the tooth root portion 1b) are composed of a single continuous tooth fabric 2.

[0109] In the embodiment shown in Figure 1, the tooth fabric constituting the surface of the tooth portion is a component of the tooth portion, while the tooth fabric constituting the surface of the tooth root portion is a component of the back portion. Furthermore, each tooth fabric constituting the tooth portion is part of a continuous tooth fabric (part of tooth fabric 2 in Figure 2).

[0110] In this example, the tooth portion 1a has a substantially trapezoidal cross-sectional shape in the circumferential direction of the belt. Furthermore, the circumferential surface (inner surface) of the tooth portion 1a, which has a substantially trapezoidal cross-section, is formed of the tooth fabric 2, and the interior is formed of a tooth rubber layer 3 interposed between the tooth fabric 2 and the core wire 4.

[0111] Furthermore, in the tooth root portion 1b, a tooth rubber layer 3 is interposed between the tooth cloth 2 and the core wire 4 (not shown). The thickness of the tooth rubber layer 3 in the tooth root portion 1b is extremely thin compared to the thickness of the tooth rubber layer 3 in the tooth portion 1a.

[0112] The core wires 4 extend in the longitudinal direction (circumferential direction) of the belt and are arranged at intervals in the width direction of the belt. The gaps between adjacent core wires 4 may be formed by the rubber composition constituting the back rubber layer 5 and / or the tooth rubber layer 3 (in particular, the rubber composition constituting the back rubber layer 5).

[0113] Toothed belts can be used for high-load power transmission applications in industrial machinery, automotive internal combustion engines, and motorcycle rear-wheel drives. For example, when a toothed belt is wrapped between a drive pulley (toothed pulley) and a driven pulley (toothed pulley), the rotation of the drive pulley transmits power from the drive pulley to the driven pulley.

[0114] It should be noted that the toothed belt of the present invention is not limited to the form and structure shown in Figures 1 and 2. For example, the multiple teeth only need to be able to mesh with a toothed pulley, and the cross-sectional shape of the teeth (the cross-sectional shape of the toothed belt in the circumferential direction) is not limited to a substantially trapezoidal shape, but may be, for example, semicircular, semielliptical, polygonal [triangle, quadrilateral (rectangle, trapezoid, etc.)], etc. Of these, a substantially trapezoidal or semicircular cross-section is preferred from the viewpoint of meshing and power transmission.

[0115] In the toothed belt of the present invention, the average distance between the centers of adjacent teeth in the circumferential direction (tooth pitch, see Figure 2) may be, for example, 2 to 25 mm, depending on the shape of the toothed pulley. The tooth pitch value corresponds to the size of the tooth scale (length of the tooth in the belt circumferential direction, and tooth height). That is, the larger the tooth pitch, the larger the tooth scale becomes. In particular, in applications where high loads are applied, teeth with a larger scale are required, and the tooth pitch may be 5 mm or more, and preferably 8 mm or more. The tooth pitch can be appropriately selected depending on the application, and in transmission applications for rear-wheel drive of motorcycles, it may be around 6 to 16 mm, for example, around 8 to 14 mm (especially 10 to 14 mm).

[0116] Furthermore, the average tooth height of the teeth is, for example, 40-70%, preferably 50-65%, of the average value of the total belt thickness [thickness (distance or height) from the back surface (outer surface) to the tooth crown].

[0117] In this application, as shown in Figure 2, the average tooth height of the teeth refers to the average height of the protruding teeth on the inner circumferential surface of the belt [the average value of the thickness (distance or height) from the tooth root surface to the tooth apex].

[0118] (Dental Department) The teeth portion includes a tooth fabric positioned on the surface side (inner surface side) and a tooth rubber layer (rubber layer forming the teeth portion) positioned or interposed between the tooth fabric and the core wire. That is, the surface of the teeth portion is covered with the tooth fabric, and the tooth fabric forms the inner circumferential surface of the belt. In the toothed belt of the present invention, the tooth fabric consists of a cloth and an impregnating component impregnated into the cloth, and since the impregnating component contains conductive carbon black, conductivity can be imparted with a simple structure without reducing strength and cost-effectiveness.

[0119] The tooth fabric may be a tooth fabric obtained from a first precursor in the manufacturing method of a toothed belt, or a tooth fabric obtained from a second precursor, but a tooth fabric obtained from a second precursor is preferred because it can improve adhesion to the tooth rubber layer.

[0120] The tooth rubber layer may be formed of a crosslinked rubber composition (first crosslinked rubber composition) that is conventionally used as the rubber composition for toothed belts. The tooth rubber layer may also be a layer (rubber layer) formed of a single phase of the crosslinked rubber composition.

[0121] The rubber hardness of the tooth rubber layer (first crosslinked rubber composition) is a type A hardness, for example 70 to 90, preferably 80 to 89, and may be about the same as the rubber hardness of the second crosslinked rubber composition that constitutes the back rubber layer described later, but it is preferable that it is higher than the rubber hardness of the second crosslinked rubber composition, and is a type D hardness, for example 60 to 80 (e.g. 60 to 66), preferably 62 to 78 (e.g. 62 to 66), more preferably 63 to 75, more preferably 63 to 72, and most preferably 63 to 70 (especially 63 to 66). If the rubber hardness is too low, the deformation resistance may decrease, and conversely, if it is too high, the flexibility of the belt, in particular, the ability to wrap around (engage) small diameter pulleys may decrease.

[0122] In this application, the Type D hardness or Type A hardness of the tooth rubber layer refers to the value (Type D hardness or Type A hardness) measured using a Type D durometer or Type A durometer in accordance with the spring durometer hardness test specified in JIS K 6253 (2012) (Vulcanized rubber and thermoplastic rubber - Method for determining hardness -), and may simply be described as hardness or rubber hardness. In detail, it can be measured by the method described in the examples below, and can be measured as the hardness of a rubber sheet obtained by crosslinking a rubber composition for forming a belt.

[0123] Typically, the rubber hardness of rubber compositions is measured using Type A hardness (a value measured using a Type A durometer). However, if the value measured using a Type A durometer exceeds 90, it is considered preferable to use a Type D durometer.

[0124] (A) Rubber component Examples of the rubber component (first rubber component) of the first crosslinked rubber composition include diene rubbers [natural rubber (NR), isoprene rubber (IR), butadiene rubber (BR), chloroprene rubber (CR), butyl rubber (IIR), styrene-butadiene rubber (SBR), vinylpyridine-styrene-butadiene rubber, acrylonitrile-butadiene rubber (nitrile rubber: NBR), acrylonitrile-chloroprene rubber, hydrogenated nitrile rubber (HNBR), etc.], ethylene-α-olefin elastomers (ethylene-propylene copolymer (EPM), ethylene-propylene-diene terpolymer (EPDM), etc.), chlorosulfonated polyethylene rubber (CSM), alkylated chlorosulfonated polyethylene rubber (ACSM), epichlorohydrin rubber, acrylic rubber, silicone rubber, urethane rubber, fluororubber, etc. These rubber components may be carboxylated, such as carboxylated SBR and carboxylated NBR. These rubber components can be used individually or in combination of two or more types.

[0125] Of these, HNBR, CR, and EPDM are preferred, and carboxylated hydrogenated nitrile rubber (HNBR) (hereinafter, including carboxylated hydrogenated nitrile rubber, sometimes simply referred to as hydrogenated nitrile rubber) is particularly preferred. The proportion of the above preferred rubber components in the rubber components is 50% by mass or more (for example, about 80-100% by mass), and particularly preferably 100% by mass. The carboxylated hydrogenated nitrile rubber may be partially hydrogenated nitrile rubber or fully hydrogenated nitrile rubber. The hydrogenation rate of the carboxylated hydrogenated nitrile rubber can be selected from a range of about 50-100%, and may be 70-100%.

[0126] In this application, HNBR refers to a rubber that maintains the oil resistance, which is an advantage of conventional nitrile rubber, while preventing the deterioration of rubber elasticity due to sulfur recombination reactions during thermal aging. This is achieved by chemically hydrogenating the unsaturated bonds (carbon-carbon double bonds) present in conventional nitrile rubber, thereby making recombination reactions during thermal aging less likely to occur and improving heat resistance.

[0127] The iodine value (unit: mg / 100 mg) of HNBR is, for example, 5 to 60 (for example, 7 to 50), preferably 8 to 40 (for example, 8 to 35), and more preferably 10 to 30.

[0128] In this application, the iodine value is an indicator of the amount of unsaturated bonds; a higher iodine value indicates a greater amount of unsaturated bonds in the polymer molecular chain. The iodine value is determined by adding an excess of iodine to the sample and allowing it to react completely (reacting with unsaturated bonds), then quantifying the remaining amount of iodine by redox titration. If the iodine value of HNBR is low, the crosslinking reaction between HNBRs is insufficient, resulting in lower rigidity of the crosslinked rubber, which may reduce deformation resistance during belt operation. On the other hand, if the iodine value of HNBR is high, the amount of unsaturated bonds becomes excessively high, which may lead to thermal and oxidative degradation of the crosslinked rubber, shortening the belt life.

[0129] The rubber component preferably contains at least hydrogenated nitrile rubber, which may be carboxylated. The proportion of such hydrogenated nitrile rubber may be 80 to 100% by mass of the rubber component, preferably 90 to 100% by mass, and more preferably 100% by mass.

[0130] The rubber component preferably contains a composite polymer or polymer alloy (hereinafter referred to as "HNBR containing an unsaturated carboxylate metal salt") comprising hydrogenated nitrile rubber and an unsaturated carboxylate metal salt. This polymer can increase the modulus and hardness of the tooth portion, suppress rubber deformation, and inhibit crack growth.

[0131] An unsaturated carboxylate metal salt may be a compound in which an unsaturated carboxylic acid having one or more carboxyl groups is ionically bonded to a metal.

[0132] Examples of unsaturated carboxylic acids in metal salts of unsaturated carboxylic acids include monocarboxylic acids such as (meth)acrylic acid and crotonic acid, dicarboxylic acids such as maleic acid, fumaric acid and itaconic acid, and monoalkyl esters of these dicarboxylic acids. These unsaturated carboxylic acids can be used alone or in combination of two or more. A preferred unsaturated carboxylic acid is (meth)acrylic acid.

[0133] Examples of metals used in unsaturated carboxylate metal salts include polyvalent metals, such as Group 2 elements of the periodic table (magnesium, calcium, etc.), Group 4 elements (titanium, zirconium, etc.), and Groups 8 to 14 elements of the periodic table (e.g., iron, cobalt, nickel, copper, zinc, aluminum, tin, lead, etc.). These metals can be used individually or in combination of two or more. Preferred metals include Group 2 elements of the periodic table (magnesium, etc.) and Group 12 elements of the periodic table (zinc, etc.).

[0134] Examples of preferred unsaturated carboxylate metal salts include zinc (meth)acrylate and magnesium (meth)acrylate. Unsaturated carboxylate metal salts can be used alone or in combination of two or more.

[0135] The mass ratio of hydrogenated nitrile rubber to unsaturated carboxylic acid metal salt can be selected from a range of approximately 100 / 80 to 100 / 180, preferably 100 / 85 to 100 / 175, and more preferably 100 / 90 to 100 / 175. If the proportion of unsaturated carboxylic acid metal salt is too low, the modulus and hardness of the crosslinked rubber composition (or teeth) may decrease, while if it is too high, the processability and flexibility of the belt will decrease.

[0136] Furthermore, commercially available HNBR containing the aforementioned unsaturated carboxylate metal salt may be used. For example, a product in which zinc methacrylate is highly finely dispersed as the unsaturated carboxylate metal salt in HNBR (e.g., Zeon Corporation's product, trade name "Zeoforte (ZSC)") can be used.

[0137] Furthermore, HNBR containing an unsaturated carboxylate metal salt is preferably used as a mixture with hydrogenated nitrile rubber (HNBR) that does not contain an unsaturated carboxylate metal salt. The mass ratio of hydrogenated nitrile rubber to unsaturated carboxylate metal salt may be adjusted by mixing commercially available HNBR containing an unsaturated carboxylate metal salt with commercially available hydrogenated nitrile rubber. The modulus and hardness may be adjusted by changing the mixing ratio of the two.

[0138] The proportion of HNBR containing unsaturated carboxylate metal salts may be 10% by mass or more of the rubber component, preferably 30% by mass or more, more preferably 50% by mass or more, more preferably 80% by mass or more, most preferably 90% by mass or more, and may be 100% by mass. In particular, the proportion of HNBR containing unsaturated carboxylate metal salts is preferably 80% by mass or more (particularly 100% by mass) of the rubber component (first rubber component) in the first rubber layer, and preferably 30% by mass or more (particularly 100% by mass) of the rubber component (second rubber component) in the second rubber layer. These proportions may be those used in the trade name "Zeoforte (ZSC)".

[0139] As other rubber components to be combined with HNBR containing an unsaturated carboxylate metal salt, at least one selected from the group consisting of HNBR, EPDM, and CR is preferred. The proportion of other rubber components is, for example, 70% by mass or less, preferably 50% by mass or less, more preferably 30% by mass or less, and most preferably 10% by mass or less, of the total rubber component.

[0140] (B) Filling compound The crosslinked rubber composition may further contain fillers. Examples of fillers (first filler) include reinforcing inorganic fillers, non-reinforcing fillers, and short fibers.

[0141] Examples of reinforcing inorganic fillers (first reinforcing inorganic filler) include carbon black and silica. These reinforcing inorganic fillers can be used individually or in combination of two or more. The reinforcing inorganic fillers may also be in powder form.

[0142] While conductive carbon black may be used, non-conductive carbon black such as furnace black is preferred due to its strength and cost-effectiveness.

[0143] The average particle size (average primary particle size) of carbon black is, for example, 5 to 200 nm, preferably 10 to 150 nm, more preferably 20 to 100 nm, and more preferably 30 to 80 nm. The amount of iodine adsorbed by carbon black is, for example, 5 to 200 mg / g, preferably 10 to 150 mg / g, more preferably 15 to 100 mg / g, and more preferably 20 to 80 mg / g.

[0144] Silica includes dry silica, wet silica, and surface-treated silica. Furthermore, silica can be classified by manufacturing method into categories such as dry-processed white carbon, wet-processed white carbon, colloidal silica, and precipitated silica. These silicas can be used individually or in combination of two or more types. Among these silicas, silica with surface silanol groups (anhydrous silicic acid, hydrated silicic acid) is preferred, and hydrated silicic acid with a high number of surface silanol groups exhibits strong chemical bonding with rubber components.

[0145] The average particle diameter (average primary particle diameter) of silica is, for example, 1 to 500 nm, preferably 3 to 300 nm, more preferably 5 to 100 nm, and more preferably 10 to 50 nm.

[0146] Furthermore, the specific surface area for nitrogen adsorption of silica by the BET method is, for example, 50 to 400 m². 2 / g, preferably 100-300m 2 / g, more preferably 150-200m 2 It is / g.

[0147] In this application, the average particle size of the reinforcing inorganic filler can be calculated as the arithmetic mean particle size of an appropriate number of samples (e.g., 50 samples) by image analysis of electron microscope images, including scanning electron microscope images.

[0148] The proportion of the reinforcing inorganic filler is, for example, 0.1 to 8 parts by mass, preferably 0.5 to 5 parts by mass, and more preferably 1 to 3 parts by mass, per 100 parts by mass of the rubber component. If the proportion of the reinforcing inorganic filler is too high, the heat generation of the rubber composition may increase, potentially reducing its heat resistance.

[0149] Examples of non-reinforcing fillers (first non-reinforcing fillers) include polyvalent metal carbonates (calcium carbonate, magnesium carbonate, etc.), polyvalent metal hydroxides (aluminum hydroxide, etc.), polyvalent metal sulfates (barium sulfate, etc.), silicates (natural or synthetic silicates in which some of the silicon is replaced by polyvalent metal atoms, such as aluminum silicate, magnesium silicate, and aluminum magnesium silicate; minerals mainly composed of silicates, such as clay containing aluminum silicate, and silicate minerals such as talc and mica containing magnesium silicate), lithopone, and silica sand. These non-reinforcing fillers can be used alone or in combination of two or more.

[0150] Preferred non-reinforcing fillers are at least one selected from calcium carbonate, magnesium carbonate, aluminum hydroxide, barium sulfate, and silicates [silicates such as aluminum silicate, magnesium silicate, and aluminum magnesium silicate; silicate minerals (talc, clay, mica, etc.)]. Furthermore, non-reinforcing fillers are preferable to include at least one selected from calcium carbonate, magnesium silicate or talc containing magnesium silicate, aluminum silicate or clay containing aluminum silicate, as they greatly improve the processability of the belt and the dispersibility of the compounding agents, and are less likely to cause poor dispersion of the compounding agents. In particular, they are preferable to include calcium carbonate. As non-reinforcing fillers, commercially available powdered fillers used as rubber fillers can be used.

[0151] The average particle size (average primary particle size) of the non-reinforcement filler can be selected from a range of approximately 0.01 to 25 μm (e.g., 0.2 to 20 μm), preferably 0.5 to 17 μm (e.g., 1 to 15 μm). The average particle size (average primary particle size) of the non-reinforcement filler may also be, for example, 0.2 to 5 μm (e.g., 0.3 to 3 μm), preferably 0.5 to 2.5 μm (particularly 1 to 2 μm). Depending on the type of non-reinforcement filler, such as magnesium silicate or its minerals, the non-reinforcement filler may be crushed or broken during the mixing process with rubber components, etc. The average particle size of such a crushable or breakable non-reinforcement filler may be the average particle size before mixing with rubber components, etc.

[0152] In this application, the average particle size of the non-reinforcing filler can be measured as the volume-average particle size using a laser diffraction particle size distribution analyzer. Furthermore, the average particle size of nanometer-sized fillers can be calculated as the arithmetic mean particle size of an appropriate number of samples (e.g., 50 samples) by image analysis of electron microscope images, including scanning electron microscope images.

[0153] The proportion of non-reinforcing filler is, for example, 70 parts by mass or less, preferably 40 parts by mass or less, and more preferably 30 parts by mass or less, per 100 parts by mass of rubber component. If non-reinforcing filler is used as needed, the proportion of non-reinforcing filler may be, for example, 3 to 50 parts by mass, preferably 5 to 30 parts by mass, and more preferably 8 to 20 parts by mass, per 100 parts by mass of rubber component. If the proportion of non-reinforcing filler is too high, the dispersibility of the compounding agent may be poor.

[0154] Short fibers (first short fibers) can be oriented (arranged) in a predetermined direction during the process of preparing an uncrosslinked rubber sheet by rolling a rubber composition kneaded in a Banbury mixer or the like using a roll or calender. In the tooth rubber layer that constitutes the teeth, it is preferable to arrange the short fibers in the direction of the belt circumference. Furthermore, it is preferable that the short fibers are oriented along the contour of the teeth on the side closer to the tooth fabric, and as they approach the core wire, the short fibers are oriented so that they are almost parallel to the core wire.

[0155] Examples of short fibers include those exemplified as fibers that form a fabric as a tooth cloth precursor. The short fibers formed from these fibers can be used alone or in combination of two or more types. Among the short fibers, fibers with a high modulus of elasticity, such as polyamide fibers, PBO fibers, glass fibers, and carbon fibers, can be preferably used, and polyamide fibers such as aliphatic polyamide fibers (nylon fibers) and aramid fibers, and PBO fibers are more preferable.

[0156] The average fiber diameter of the short fibers is, for example, 1 to 100 μm (e.g., 3 to 70 μm), preferably 5 to 50 μm (e.g., 7 to 30 μm), and more preferably 10 to 25 μm (particularly 12 to 20 μm). The average fiber length of the short fibers is, for example, 0.3 to 10 mm (e.g., 0.5 to 7 mm), preferably 1 to 5 mm (particularly 2 to 4 mm). If the average fiber diameter of the short fibers is too small or the average fiber length is too long, there is a risk that the short fibers will not be able to be dispersed uniformly, and if the average fiber diameter is too large or the average fiber length is too short, there is a risk that the strength of each rubber layer will decrease.

[0157] Adding short fibers can increase the modulus and hardness of the crosslinked rubber composition, but it also makes the interface between the rubber component and the short fibers more prone to developing microcracks. Therefore, it is necessary to adjust the amount of short fibers to an appropriate level. The proportion of short fibers is 10 parts by mass or less, preferably 7 parts by mass or less, and more preferably 5 parts by mass or less (for example, 0.5 to 5 parts by mass) per 100 parts by mass of rubber component.

[0158] Furthermore, it is preferable to apply a conventional adhesive treatment (or surface treatment) to the short fibers to adhere an adhesive component to at least a portion of the surface of the short fibers. Such an adhesive treatment improves the adhesion between the short fibers and the rubber component and suppresses the generation of microcracks originating from the interface between the short fibers and the rubber component. Examples of adhesive treatments include treatment with adhesive components such as epoxy compounds (or epoxy resins), polyisocyanates, silane coupling agents, and RFL liquid.

[0159] The proportion of the filler compound is, for example, 3 to 70 parts by mass, preferably 5 to 50 parts by mass, more preferably 10 to 40 parts by mass, and more preferably 20 to 30 parts by mass, per 100 parts by mass of the rubber component.

[0160] (C) Cross-linking compounding agent The rubber composition contains a crosslinking agent (vulcanizing agent) to crosslink the rubber components, and, if necessary, co-crosslinking agents, crosslinking aids (vulcanization aids), crosslinking accelerators (vulcanization accelerators), crosslinking retarders (vulcanization retarders), etc.

[0161] As the crosslinking agent (first crosslinking agent), conventional components can be used depending on the type of rubber component, and examples include organic peroxides, sulfur-based crosslinking agents, and metal oxides.

[0162] Examples of organic peroxides (first organic peroxides) include di-t-butyl peroxide, dicumyl peroxide, t-butylcumyl peroxide, 1,1-t-butylperoxy-3,3,5-trimethylcyclohexane, 1,3-bis(t-butylperoxyisopropyl)benzene, 2,5-dimethyl-2,5-di(t-butylperoxy)hexane, 2,5-dimethyl-2,5-di(t-butylperoxy)hexyn-3, 1,3-bis(t-butylperoxy-di-isopropyl)benzene, 2,5-di-methyl-2,5-di(benzoylperoxy)hexane, t-butylperoxybenzoate, and t-butylperoxy-2-ethyl-hexyl carbonate. These organic peroxides can be used individually or in combination of two or more.

[0163] Examples of sulfur-based crosslinking agents include powdered sulfur, precipitated sulfur, colloidal sulfur, insoluble sulfur, highly dispersible sulfur, and sulfur chloride (sulfur monochloride, sulfur dichloride, etc.). These sulfur-based crosslinking agents can be used individually or in combination of two or more.

[0164] Examples of metal oxides (first metal oxides) include magnesium oxide, zinc oxide, and lead oxide. These metal oxides can be used individually or in combination of two or more.

[0165] The crosslinking agent can be appropriately selected depending on the type of rubber component, with organic peroxides and metal oxides being preferred, and organic peroxides being particularly preferred.

[0166] The proportion of the crosslinking agent is, for example, 1 to 20 parts by mass, preferably 3 to 15 parts by mass, and more preferably 5 to 10 parts by mass, per 100 parts by mass of the rubber component. If the proportion of the crosslinking agent is too low, the modulus and hardness of the rubber composition will decrease, while if it is too high, the flexibility of the belt will decrease.

[0167] The proportion of organic peroxide is, for example, 0.5 to 10 parts by mass, preferably 0.8 to 5 parts by mass, more preferably 1 to 4 parts by mass, and more preferably 1.5 to 3 parts by mass, per 100 parts by mass of rubber component.

[0168] The proportion of the metal oxide is, for example, 1 to 20 parts by mass, preferably 1.5 to 15 parts by mass, more preferably 2 to 10 parts by mass, and more preferably 3 to 8 parts by mass, per 100 parts by mass of the rubber component.

[0169] The proportion of the crosslinking compound is, in terms of solid content, for example, 1 to 50 parts by mass, preferably 3 to 40 parts by mass, and more preferably 5 to 30 parts by mass, per 100 parts by mass of rubber component.

[0170] (D) Other compounding agents The crosslinked rubber composition may further contain conventional additives used in rubber compositions for toothed belts. Conventional additives include, for example, metal oxides (calcium oxide, barium oxide, iron oxide, copper oxide, titanium oxide, aluminum oxide, etc.), softeners (oils such as paraffin oil and naphthenic oils), processing agents or processing aids (stearic acid or its metal salts, waxes, paraffin, fatty acid amides, etc.), plasticizers (first plasticizer) [aliphatic carboxylic acid plasticizers (adipate ester plasticizers, sebacate ester plasticizers, etc.), aromatic carboxylic acid Examples of additives include ster-type plasticizers (phthalate ester plasticizers, trimellitic acid ester plasticizers, etc.), oxycarboxylic acid ester plasticizers, phosphate ester plasticizers, ether plasticizers, ether ester plasticizers, etc.), anti-aging agents (oxidants, heat aging inhibitors, flex crack inhibitors, ozone degradation inhibitors, etc.), colorants, tackifiers, plasticizers, coupling agents (silane coupling agents, etc.), stabilizers (UV absorbers, heat stabilizers, etc.), flame retardants, and antistatic agents. The crosslinked rubber composition may also contain adhesion improvers (resorcinol-formaldehyde cocondensates, amino resins, etc.) as needed. These additives can be used individually or in combination of two or more.

[0171] The total proportion of these additives is, for example, 1 to 50 parts by mass, preferably 1.5 to 40 parts by mass, and more preferably 2 to 30 parts by mass, in terms of solid content, per 100 parts by mass of rubber component.

[0172] The first crosslinked rubber composition (tooth rubber layer) may or may not contain conductive additives such as metal powder and conductive carbon black, but it is preferable that it substantially does not contain conductive additives, and it is particularly preferable that it does not contain conductive additives. In the present invention, the conductivity of the toothed belt can be improved even when a tooth rubber layer without conductive additives is used.

[0173] (Tooth root) The tooth cloth constitutes the surface of the tooth portion, as well as the surface on the tooth side of the back (the surface of the tooth root).

[0174] In the dorsal portion corresponding to the tooth root, a tooth rubber layer may be interposed between the tooth cloth and the core wire, or the tooth cloth and core wire may be in contact without the tooth rubber layer. Even when a tooth rubber layer is interposed in the dorsal portion corresponding to the tooth root, the thickness of the tooth rubber layer is formed to be thinner than that of the tooth portion.

[0175] (back) The back portion has the teeth and tooth roots formed on its inner circumferential surface, and on its outer circumferential surface, it has a back rubber layer that forms the outer circumferential surface of the belt. Furthermore, the back rubber layer is made of a crosslinked rubber composition (second crosslinked rubber composition). In the embodiment shown in Figure 1, the other surface (back of the belt) on the side where the teeth are not formed is not covered with a fabric (woven fabric, knitted fabric, nonwoven fabric, etc.), but it may be covered if necessary. This fabric can be selected from the fabrics exemplified as tooth fabrics, including in preferred embodiments.

[0176] The hardness of the second crosslinked rubber composition may be the same as, or different from, the hardness of the first crosslinked rubber that constitutes the teeth. However, it is preferable that the hardness of the second crosslinked rubber composition is lower than that of the first crosslinked rubber composition that constitutes the teeth, in order to reduce the bending rigidity of the belt and ensure flexibility (ease of wrapping around the pulley) and bending fatigue resistance.

[0177] Specifically, the rubber hardness of the second crosslinked rubber composition is, for example, 70 to 90, preferably 80 to 89, on a Type A hardness scale. If the Type A hardness of the second crosslinked rubber composition is too low, cracks may occur on the back due to impacts from foreign objects, etc. Conversely, if it is too high, the flexural fatigue resistance will decrease, and cracks may occur on the back.

[0178] The second crosslinked rubber composition is not particularly limited as long as it does not impair the adhesion between the back rubber layer and the tooth portion, and can be selected from, for example, the crosslinked rubber compositions exemplified as the first crosslinked rubber composition, and can be appropriately adjusted so that the rubber hardness falls within the aforementioned range.

[0179] In the second crosslinked rubber composition, the rubber component (second rubber component) preferably contains the same series or type of rubber component as the tooth rubber layer, and more preferably the same type of rubber component, in order to improve the adhesion between the back rubber layer and the tooth portion.

[0180] The second rubber component preferably contains HNBR containing an unsaturated carboxylate metal salt. The proportion of HNBR containing an unsaturated carboxylate metal salt may be 5% by mass or more of the second rubber component, for example, 5 to 50% by mass, preferably 10 to 30% by mass, and more preferably 15 to 25% by mass. The second rubber component may also be a combination of HNBR without an unsaturated carboxylate metal salt and HNBR containing an unsaturated carboxylate metal salt.

[0181] The filling compound (second filling compound) may be a reinforcing inorganic filler (second reinforcing inorganic filler), and a combination of carbon black and silica is preferred. The proportion of carbon black is, for example, 1 to 50 parts by mass, preferably 2 to 30 parts by mass, and more preferably 3 to 10 parts by mass, per 100 parts by mass of silica. The proportion of the second reinforcing inorganic filler is, for example, 10 to 100 parts by mass, preferably 20 to 80 parts by mass, and more preferably 30 to 50 parts by mass, per 100 parts by mass of the second rubber component.

[0182] The crosslinking agent (second crosslinking agent) may be a combination of an organic peroxide (second organic peroxide) and a metal oxide (second metal oxide). The proportion of the second crosslinking agent is, for example, 1 to 20 parts by mass, preferably 2 to 15 parts by mass, and more preferably 3 to 10 parts by mass, per 100 parts by mass of the second rubber component. The proportion of the second organic peroxide is, for example, 0.5 to 10 parts by mass, preferably 0.8 to 5 parts by mass, more preferably 1 to 4 parts by mass, and more preferably 1.5 to 3 parts by mass, per 100 parts by mass of the second rubber component. The proportion of the second metal oxide is, for example, 1 to 10 parts by mass, preferably 1 to 5 parts by mass, and more preferably 1.5 to 3 parts by mass, per 100 parts by mass of the second rubber component.

[0183] The second crosslinked rubber composition may contain a plasticizer (second plasticizer). The plasticizer can be selected from the plasticizers exemplified as the first plasticizer. The plasticizer can be used alone or in combination of two or more. Among the plasticizers, ether ester plasticizers are preferred.

[0184] The proportion of the second plasticizer is, for example, 1 to 50 parts by mass, preferably 2 to 30 parts by mass, more preferably 3 to 20 parts by mass, and more preferably 5 to 15 parts by mass, per 100 parts by mass of the second rubber component.

[0185] The second crosslinked rubber composition may further contain conventional additives used in rubber compositions for toothed belts. Examples of conventional additives include those exemplified as conventional additives (additives other than plasticizers) for the first crosslinked rubber composition. The additives can be used individually or in combination of two or more. The total proportion of the additives is, for example, 1 to 50 parts by mass, preferably 1.5 to 40 parts by mass, and more preferably 2 to 30 parts by mass, in terms of solid content, per 100 parts by mass of the second rubber component.

[0186] The back portion and the second crosslinked rubber composition (back rubber layer) may or may not contain conductive additives such as metal powder and conductive carbon black, but it is preferable that they substantially not contain conductive additives, and it is particularly preferable that they not contain conductive additives. In the present invention, the conductivity of the toothed belt can be improved even when using a back portion and back rubber layer that do not contain conductive additives.

[0187] The average thickness of the back rubber layer is, for example, 0.3 to 3 mm, preferably 0.5 to 2 mm. The average thickness of the back portion (average thickness of the back portion at the tooth root) is, for example, 1 to 5 mm, preferably 1.5 to 4 mm.

[0188] (Core wire) On the back of the belt, a core wire extending along the belt circumferential direction is embedded on the inner circumference side of the back rubber layer. This core wire acts as a tensile body, improving the running stability and strength of the toothed belt. Furthermore, on the back, the core wire, which is usually a twisted cord extending along the belt circumferential direction, is embedded at predetermined intervals in the belt width direction. Multiple core wires parallel to the longitudinal direction may be arranged, but from the viewpoint of productivity, they are usually embedded in a spiral shape. When arranged in a spiral shape, the angle of the core wire with respect to the longitudinal direction of the belt may be, for example, 5° or less, and from the viewpoint of belt running performance, it is preferable that it is as close to 0° as possible.

[0189] More specifically, the core wires may be embedded at predetermined intervals (or pitches) (or at equal intervals) from one end to the other in the belt width direction on the back, as shown in Figure 1. The spacing (spinning pitch), which is the distance between the centers of adjacent core wires, should be greater than the core wire diameter, and depending on the core wire diameter, it may be, for example, 0.5 to 3.5 mm, preferably 0.8 to 3 mm, and more preferably 1 to 2.8 mm.

[0190] The core wire may be formed from a twisted cord made by twisting together multiple strands or multifilament yarns. Of these, a twisted cord of strands is preferred, and one strand may be formed by bundling filaments (long fibers). There are no particular restrictions on the thickness of the filaments forming the twisted cord, the number of filaments converged, the number of strands, and the twist configuration. The twisted cord forming the core wire may be a single-ply, double-ply, or Lang-ply cord.

[0191] The fibers forming the core are not particularly limited, and examples include synthetic fibers such as polyester fibers (polyalkylene arylate fibers, poly-p-phenylene naphthalate fibers), polybenzoxazole fibers, acrylic fibers, and polyamide fibers (aliphatic polyamide fibers, aramid fibers, etc.), as well as inorganic fibers such as glass fibers, carbon fibers, and metal fibers (steel fibers). These fibers can be used individually or in combination of two or more types. From the viewpoint of low elongation and high strength, synthetic fibers such as polyester fibers and polyamide fibers, and inorganic fibers such as glass fibers and carbon fibers are commonly used as fibers forming the core.

[0192] In applications involving particularly high loads, multifilament carbon fiber yarns are preferably used. Examples of carbon fibers used include "Torayca," manufactured by Toray Industries, Inc.

[0193] Carbon fiber multifilament yarns can be selected from multifilament yarns with different filament counts, such as 6K and 12K. 6K refers to a multifilament yarn with 6,000 filaments, and 12K refers to a multifilament yarn with 12,000 filaments. The fineness of 6K multifilament yarn is approximately 400 tex, and the fineness of 12K multifilament yarn is approximately 800 tex.

[0194] If the fineness of the carbon fiber multifilament yarn is greater than 1000 tex, the bending fatigue resistance of the toothed belt may decrease. Conversely, if the fineness of the carbon fiber multifilament yarn is less than 300 tex, the material cost increases, and the number of under-twisted yarns required to produce a core wire with sufficient tensile strength increases, leading to an increase in labor costs.

[0195] In one embodiment of the toothed belt of the present invention, a Lang-twisted carbon fiber cord (12K-1 / 4) is used as the core wire, which is made by first twisting one 12K multifilament yarn (fineness approximately 800 tex) to create a pre-twisted yarn, and then twisting four of these pre-twisted yarns together. Alternatively, a carbon fiber cord (12K-1 / 0) made by single-twisting one 12K multifilament yarn (fineness approximately 800 tex) may be used as the core wire. Note that "12K-1 / 0" indicates a twisted cord made by single-twisting one 12K multifilament yarn, and "12K-1 / 4" indicates a twisted cord made by first twisting one 12K multifilament yarn to create a pre-twisted yarn, and then twisting four of these pre-twisted yarns together. Similarly, for example, "12K-1 / 3" indicates a twisted cord made by first twisting one 12K multifilament yarn to create a base twist, then combining three of these base twists and twisting them together. "12K-4 / 0" indicates a twisted cord made by combining four 12K multifilament yarns and twisting them together in a single-ply manner.

[0196] The core wires may be treated with an adhesive coating to enhance their adhesion to the cross-linked rubber composition. For example, the adhesive coating may involve immersing the stranded cord in RFL solution, followed by heating and drying to form a uniform adhesive layer on the surface of the stranded cord. Alternatively, the adhesive coating may involve pre-treating the cord with an epoxy compound or isocyanate compound before treating it with the RFL solution.

[0197] The average diameter (average wire diameter) of the stranded cord (or core wire) is, for example, 0.2 to 2.5 mm, preferably 0.5 to 2.3 mm, more preferably 0.7 to 2.2 mm, and 0.8 to 2.1 mm is preferred, especially in applications where high loads are applied. If the core wire diameter is too thin, the elongation of the core wire will increase, which may cause tooth breakage (loss of teeth). If the core wire diameter is too thick, the bending fatigue resistance of the core wire will decrease, which may cause core wire breakage. In one embodiment of the present invention, the core wire diameter is adjusted to 2.0 mm.

[0198] (Characteristics of toothed belts) The toothed belt of the present invention has high conductivity, for example, an electrical resistance value R of 6.8 × 105 It is preferable that the electrical resistance is less than or equal to ×L / W(Ω) [where L is the distance between electrodes (mm) and W is the width of the electrodes (mm) (however, if the width of the belt is smaller than the width of the electrodes, then the width of the belt)]. The specific electrical resistance value can be selected according to the type of toothed belt, but for example it is 2.88 MΩ or less (particularly 1.5 MΩ or less), for example 0.001 to 2.88 MΩ, preferably 0.01 to 2.5 MΩ, more preferably 0.05 to 2 MΩ, more preferably 0.05 to 1.5 MΩ, and most preferably 0.07 to 1.2 MΩ. These electrical resistance values ​​may also be the electrical resistance values ​​of the belt after use.

[0199] In this application, the electrical resistance of the toothed belt can be measured by the method described in the examples below.

[0200] [How to manufacture a toothed belt] The present invention relates to a method for manufacturing a toothed belt, and any method that includes a step for obtaining a tooth fabric precursor (a first processing step, or a first processing step and a second processing step) is acceptable, and examples include a pre-forming method using the obtained tooth fabric precursor. The pre-forming method may include the following precursor production step, pre-forming step, cross-linking step, and cutting step.

[0201] (Precursor preparation process) First, in the precursor preparation process, in addition to the tooth cloth precursor obtained by the method of the present invention, an uncrosslinked rubber sheet that forms the tooth rubber layer and an unvulcanized rubber sheet that forms the back rubber layer are prepared.

[0202] (Pre-molding process) Next, a tooth cloth precursor is wrapped around the outer surface of a cylindrical mold having multiple grooves (recesses) corresponding to the teeth of a toothed belt. Subsequently, a laminate is formed by wrapping an uncrosslinked rubber sheet, which will form the tooth rubber layer, around its outer surface. The laminate is then heated in a predetermined device to a temperature (for example, about 70-90°C) at which the rubber composition softens, and pressure is applied from the outer side to press-fit the rubber composition of the uncrosslinked rubber sheet and the tooth cloth precursor into the grooves (recesses) of the cylindrical mold, thereby forming the teeth and obtaining a semi-crosslinked pre-molded body. In this press-fitting process to form the teeth, the tooth cloth is stretched to conform to the contour of the teeth and positioned on the outermost surface, and a structure is formed in which the tooth rubber layer is positioned on the inside.

[0203] Alternatively, instead of using a cylindrical mold, a flat press mold (flat mold) having multiple grooves (recesses) corresponding to the teeth may be used to form the teeth by press-fitting the rubber composition of the uncrosslinked rubber sheet and the tooth fabric precursor into the grooves (recesses) of the flat mold using the above procedure. In this method, after demolding the preform from the flat mold, the preform is wrapped around and mounted (fitting the teeth and grooves) onto a cylindrical mold having multiple grooves (recesses) corresponding to the teeth, and the process moves to the next step.

[0204] (Crosslinking molding process) The twisted cord constituting the core wire is wound spirally around the outer surface of the obtained pre-molded body at a predetermined pitch (so that the pitch is predetermined in the axial direction of the cylindrical mold). Furthermore, an uncrosslinked rubber sheet that will form the back rubber layer is wound around the outer surface to form an uncrosslinked belt molded body (uncrosslinked laminate).

[0205] Next, with the uncrosslinked belt molded body positioned on the outer circumference of the cylindrical mold, a rubber jacket, which acts as a vapor barrier, is placed over it. Subsequently, the jacketed belt molded body and the cylindrical mold are housed inside a crosslinking molding device such as a vulcanizing can. When the belt molded body is heated and pressurized inside the crosslinking molding device, the desired shape is formed, and the crosslinking reaction of the uncrosslinked and semi-crosslinked rubber components contained in the belt molded body causes each component to join together and harden integrally, forming a sleeve-shaped crosslinked molded body (crosslinked belt sleeve).

[0206] (cutting process) Finally, multiple toothed belts are obtained by cutting the bridging belt sleeve, which has been demolded from the cylindrical mold, to a predetermined width. [Examples]

[0207] The present invention will be described in more detail below based on examples, but the present invention is not limited to these examples. The raw materials used, preparation methods, evaluation methods, etc., are shown below.

[0208] [Rubber composition]

[0209] [Table 1]

[0210] [Materials for rubber compositions] HNBR: Zetpol 2010, manufactured by Nippon Zeon Co., Ltd., iodine value 11 mg / 100 mg HNBR containing unsaturated metal carboxylate: Zeon Corporation's "Zeoforte ZSC2295CX," base HNBR:unsaturated metal carboxylate (mass ratio) = 100:110, iodine value of base HNBR 28 mg / 100 mg Aramid short fibers: "Conex" manufactured by Teijin Limited, average fiber length 3 mm, average fiber diameter 14 μm Stearic acid: "Stearic acid Tsubaki" manufactured by NOF Corporation. Carbon black SRF: "Seas S" manufactured by Tokai Carbon Co., Ltd., average particle size 66 nm, iodine adsorption capacity 26 mg / g Silica: "UltraSil VN-3" manufactured by Evonik Degussa Japan Co., Ltd., specific surface area 155-195 m² 2 / g Calcium carbonate: Maruo Calcium Co., Ltd. "Super #1500", average particle size 1.5 μm Zinc oxide: "Zinc Oxide Type 2" manufactured by Sakai Chemical Industry Co., Ltd., average particle size 0.55 μm Organic peroxide: 1,3-bis(t-butylperoxyisopropyl)benzene, theoretical reactive oxygen species content 9.45% Plasticizer: ADEKA Corporation's "ADEKA Sizer RS700" Anti-aging agent: p,p'-dioctyldiphenylamine, manufactured by Seiko Chemical Co., Ltd. ("Nonflex OD3")

[0211] [Rubber hardness of cross-linked rubber] A block of uncrosslinked rubber composition having the composition shown in Table 1 was passed through a calender roll to prepare an uncrosslinked rolled rubber sheet of a predetermined thickness. The obtained uncrosslinked rolled rubber sheet was then press-heated at 165°C for 30 minutes to produce a crosslinked rubber sheet (100 mm × 100 mm × 2 mm thickness). A laminate of three crosslinked rubber sheets was used as a sample, and the rubber hardness (Type D hardness or Type A hardness) of the crosslinked rubber sheet was measured using a Type D durometer or Type A durometer in accordance with the spring durometer hardness test specified in JIS K 6253 (2012) (Vulcanized rubber and thermoplastic rubber - Method for determining hardness -). The test temperature was 23°C.

[0212] [Heart wire] A single 12K multifilament yarn [Toray Industries, Inc.'s "Torayca T700SC-12000", single filament fineness 0.67 dtex, total fineness 800 tex, tensile modulus 230 GPa] was twisted to produce a base twist yarn. Four of these base twist yarns were then combined and twisted to produce a Lang-twisted carbon fiber cord (12K-1 / 4). This cord was then bonded with an HNBR-based overcoat to obtain a core wire with a diameter of 2.0 mm.

[0213] Examples 1-15 and Comparative Examples 1-5 [Tooth cloth precursors and processing of tooth cloth precursors] In Examples 1-13 and Comparative Examples 1-5, the woven fabric A shown in Table 2 was immersed for 5 seconds in the first treatment solution (first bath) at 25°C shown in Tables 5-7, then removed from the first bath and subjected to a squeezing pressure of 5 kgf / cm². 2 The excess immersion liquid was removed by passing the fabric through a squeezing roller. Subsequently, the fabric was dried at 170°C for 5 minutes, and then immersed for 5 seconds in the second treatment solution (second bath) shown in Tables 5-7. After removing the fabric from the second bath, it was squeezed at a pressure of 5 kgf / cm². 2 The material was passed through a squeezing roller to remove excess immersion liquid. Subsequently, it was dried at 170°C for 5 minutes to obtain a tooth cloth precursor.

[0214] [Woven fabric A]

[0215] [Table 2]

[0216] In Example 14, a tooth cloth precursor was obtained in the same manner as in Example 1, except that the immersion treatment using the second treatment solution was not performed.

[0217] In Example 15, a tooth cloth precursor was obtained in the same manner as in Example 1, except that woven fabric B shown in Table 3 was used instead of woven fabric A shown in Table 2, and the tooth cloth precursor was immersed in the first and second treatment solutions at 25°C shown in Table 6.

[0218] [Woven fabric B]

[0219] [Table 3]

[0220] [Materials for woven fabrics A and B] Polyamide yarn: 66 nylon fiber PTFE yarn: "Toyoflon 1330dtex" manufactured by Toray Industries, Inc. Polyester yarn: "Cornetta" manufactured by Unitika Ltd., a core-sheath type composite fiber with a core melting point of 256°C and a sheath melting point of 160°C.

[0221] [Materials for the first and second treatment solutions] HNBR latex: Zeon Corporation's "Zetpol 2230LX", solid content concentration 40.5% by mass Vp Latex: "Nipol 2518FSH" manufactured by Nippon Zeon Co., Ltd., solid content concentration 40.5% by mass CR Latex: "LV-61" manufactured by Denka Co., Ltd., solid content concentration 60.0% by mass RF condensate A: R / F = 1 / 1 (molar ratio), solid content concentration 20.0% by mass RF condensate B: R / F = 1 / 1.5 (molar ratio), solid content concentration 20.0% by mass Sodium hydroxide aqueous solution: Sodium hydroxide concentration 10% by mass Maleimide compound aqueous dispersion: Maleimide compound concentration 50% by mass Conductive carbon black dispersion A: "9537BLACK" manufactured by Tokushiki Co., Ltd., solid content concentration 13.5% by mass Conductive carbon black dispersion B: Lion Paste W-370C, manufactured by Lion Specialty Chemicals Co., Ltd., solid content concentration 15.5% by mass Conductive carbon black dispersion C: Lion Paste W-311N, manufactured by Lion Specialty Chemicals Co., Ltd., solid content concentration 16.5% by mass Carbon black dispersion: Fuji SP Black 203, manufactured by Fuji Pigment Co., Ltd., solid content concentration 28.0% by mass.

[0222] [Preparation of uncrosslinked rubber sheets] For forming the teeth and back (back rubber layer), each rubber composition shown in Table 1 was kneaded using a Banbury mixer, and the resulting kneaded rubber was rolled to a predetermined thickness using a calender roll to produce an uncrosslinked rubber sheet. The short fibers contained in the uncrosslinked rubber sheet were oriented in the rolling direction.

[0223] [Manufacturing of toothed belts] In the examples and comparative examples, as shown below, toothed belts with a total thickness of 9.8 mm, tooth profile G14M, tooth height (including tooth cloth) of 6.1 mm, tooth pitch of 14 mm, number of teeth of 80, circumference of 1120 mm, and width of 20 mm were manufactured using the pre-forming method described in this embodiment.

[0224] In detail, a press mold (flat type) having multiple grooves (recesses) corresponding to the teeth of a toothed belt was used to laminate a tooth fabric precursor for forming the tooth fabric and an uncrosslinked rubber sheet (sheet thickness 2.8 mm) for forming the tooth rubber layer. The mold was then pressed for 160 seconds at a temperature of 90°C and a press pressure (surface pressure) of 45 MPa to produce a semi-crosslinked pre-molded body. The orientation direction of the short fibers was set to the circumferential direction of the belt.

[0225] Next, a pre-molded body was wrapped around a cylindrical mold and attached (fitting the teeth and grooves), and stranded cords forming the core wires were spun spirally around the outer surface of the pre-molded body (tension: 550N / strand, spinning pitch: 2.35mm / strand, spinning speed: 1.5m / s). Furthermore, an uncrosslinked rubber sheet (sheet thickness 1.5mm) that forms the back rubber layer was wrapped around the outer surface to form an uncrosslinked belt molded body (uncrosslinked laminate).

[0226] Next, using a vulcanizing vessel, cross-linking molding was performed for 40 minutes under conditions of a heating temperature of 180°C and a vapor pressure of 0.9 MPa to produce a cross-linked molded body (cross-linked belt sleeve).

[0227] Finally, a toothed belt was obtained by cutting the bridging belt sleeve, which had been demolded from the cylindrical mold, to a width of 20 mm.

[0228] [Dental fabric release force] The force required to detach the tooth fabric of a toothed belt was compared. Specifically, an autograph was used to detach the tooth fabric of a 20 mm wide toothed belt in the length direction of the belt at a speed of 50 mm / min. The detachment force was large at the tooth apex and tooth sides and small at the tooth root. The detachment force of the tooth fabric at the tooth root was measured for five consecutive teeth, and the average value was calculated. The tooth fabric detachment force is expressed as a relative value with Comparative Example 5 set to 100.

[0229] [Electrical resistance value (conductivity test)] The electrical resistance of the belt tooth surface was measured in accordance with the laboratory method specified in ISO 9563 (2015). As shown in Figure 3, a toothed belt 11 with a width of 20 mm was set on an insulating resin plate 12 with the tooth surface facing upwards. A pair of brass electrodes 13 with a width (W) of 20 mm were fitted onto the tooth surface with a distance (L) of 96 mm between the electrodes. A weight 15 was placed on both electrodes 13 via a weight stand 14, applying a total load of 1.5 kgf. After attaching the terminals of an insulation resistance meter to the electrodes 13, a voltage of 500 V was applied, and the electrical resistance was measured 5 seconds after the voltage was applied. The measurement was performed at a room temperature of 23°C and a relative humidity of 50%. Before fitting the electrodes 13 to the toothed belt 11, conductive paint (Polycalm PTP-G1501, manufactured by Pluscoat Co., Ltd.) was applied between the toothed belt 11 and the electrodes 13. Electrical resistance was measured at five points, dividing the belt length into approximately five equal parts, and the average value was used. A smaller electrical resistance value indicates a better effect in preventing static electricity buildup on the belt, and the electrical resistance value R of the belt tooth surface was determined to be R = 6 × 10⁻⁶. 5 A test is considered successful if the electrical resistance value (conductivity) does not exceed R = 6 × 10⁻¹⁰. In other words, under the above measurement conditions, the pass / fail condition for electrical resistance (conductivity) is determined by the upper limit of the electrical resistance value R = 6 × 10⁻¹⁰. 5 ×96 / 20 = 2.88 × 10 6 Since (Ω) = 2.88 (MΩ), an electrical resistance value of 2.88 MΩ or less was considered acceptable.

[0230] [Durability test (lifespan)] As shown in Figure 4, a toothed belt was mounted on a two-axis running test machine equipped with a drive (Dr.) pulley and a driven (Dn.) pulley with 28 teeth each. The belt was run until the end of its lifespan at an ambient temperature of 25°C (room temperature) with an axle load of 1930N, a drive pulley rotation speed of 1800rpm, and a driven pulley load of 225N·m. Electrical resistance values ​​were measured before and after the endurance running test, and conductivity was determined according to the following criteria.

[0231] (Judgment criteria) The criteria shown in Table 4 were used for evaluation, and toothed belts with a rating of b or higher were deemed acceptable from the standpoint of electrical conductivity. Specifically, a rating of a means that the resistance was less than 0.50 MΩ both before and after the endurance driving test, a rating of b means that the resistance was between 0.50 MΩ and 2.88 MΩ at either the before or after the endurance driving test without exceeding 2.88 MΩ, and a rating of c means that the resistance was greater than 2.88 MΩ at either the before or after the endurance driving test.

[0232] [Table 4]

[0233] The test results for the toothed belts of the examples and comparative examples are shown in Tables 5 to 7. In the tables, the carbon solids concentration indicates the concentration of solids derived from the conductive carbon black dispersion in the treatment agent, and the carbon adhesion rate indicates the adhesion rate (solids / fabric ratio) of solids derived from the conductive carbon black dispersion (or carbon black dispersion) to the fabric (raw material).

[0234] [Table 5]

[0235] [Table 6]

[0236] [Table 7]

[0237] As is clear from the results in Tables 5 and 6, the toothed belts of Examples 1 to 15 maintained relatively high tooth fabric peeling force while exhibiting low electrical resistance and a long lifespan. Furthermore, comparisons between Example 7 and Example 11, and between Example 8 and Example 12, showed that the lifespan decreased when the second bath contained carbon black.

[0238] In Example 14, the pre-run electrical resistance was low because the first treatment agent containing conductive carbon black was used for treatment. On the other hand, because the second treatment agent was not used, the tooth cloth was more prone to wear during running, and the post-run electrical resistance was slightly higher, but it still met the acceptable standard. Also, perhaps because the second treatment agent was not used, the tooth cloth peeling force was lower, but there were no problems such as peeling during the running test.

[0239] Example 15 uses a tooth fabric woven from 66 nylon and urethane elastic yarn, without containing PTFE yarn in the weft. Compared to a tooth fabric containing PTFE yarn in the weft, the tooth fabric was more prone to wear, and the electrical resistance value was slightly higher after operation, but it still met the acceptable standards.

[0240] On the other hand, as is clear from the results in Table 7, Comparative Example 1, despite having a low carbon solid content concentration, exhibited high electrical resistance after operation. Comparative Example 2, also with a low RFL solid content concentration, had a short lifespan and high electrical resistance after operation. Furthermore, Comparative Examples 3 and 4, which did not contain conductive carbon black, exhibited high electrical resistance. In addition, Comparative Example 5, which did not contain carbon black, also exhibited high electrical resistance. [Industrial applicability]

[0241] The toothed belt (meshing transmission belt or toothed transmission belt) of the present invention can be used in combination with a toothed pulley in various fields where synchronization between input and output is required, such as power transmission mechanisms in vehicles such as automobiles and motorcycles, power transmission mechanisms such as motors and pumps in industrial machinery, machinery such as automatic doors and automated machines, office automation equipment parts, coin handling equipment, photocopiers, and printers. [Explanation of Symbols]

[0242] 1…Toothed belt 1a...teeth part 1b...Root of the tooth 1c...back 2… Toothcloth 3…Tooth rubber layer 4… Core wire 5... Back rubber layer

Claims

1. A treatment agent for manufacturing tooth fabric for toothed belts, A mixture comprising a first RFL liquid containing a first RFL component consisting of resorcinol, formaldehyde, and latex, and a first conductive dispersion containing a first conductive carbon black, A first treatment agent wherein the solid content of the first RFL component in the mixed liquid is 10% by mass or more, and the solid content of the first conductive dispersion is 4 to 10% by mass.

2. The first treatment agent according to claim 1, wherein the proportion of solids in the mixed liquid is 4.5 to 8% by mass of the first conductive dispersion.

3. The first treatment agent according to claim 1 or 2, wherein the proportion of solid content of the first RFL component in the mixed liquid is 13% by mass or more.

4. A method for manufacturing a toothed belt, comprising a first processing step of processing a cloth as a tooth cloth precursor with a first processing agent according to any one of claims 1 to 3 to obtain a first precursor.

5. The manufacturing method according to claim 4, further comprising a second processing step of treating the first precursor with a second processing agent comprising a second RFL component consisting of resorcinol, formaldehyde, and latex to obtain a second precursor.

6. The manufacturing method according to claim 5, wherein the second treatment agent does not contain conductive carbon black.

7. The manufacturing method according to claim 5 or 6, wherein the second treatment agent is a mixture comprising a second RFL liquid containing a second RFL component consisting of resorcinol, formaldehyde, and latex, and a second conductive dispersion containing a second conductive carbon black, and the proportion of solids in the second conductive dispersion in the second treatment agent is less than the proportion of solids in the first conductive dispersion in the first treatment agent.

8. The manufacturing method according to any one of claims 5 to 7, wherein the proportion of solids of the second RFL component in the second treatment agent is equal to or greater than the proportion of solids of the first RFL component in the first treatment agent.

9. The manufacturing method according to any one of claims 5 to 8, wherein the second treatment agent further comprises a maleimide compound.

10. A toothed belt obtained by the manufacturing method described in any one of claims 4 to 9.

11. The back portion has a core wire embedded in it that extends along the circumference of the belt, The inner circumferential surface of the back portion is provided with a plurality of teeth formed at intervals in the circumferential direction of the belt, It includes a back rubber layer formed on the outer circumference side of the belt relative to the core wire, and a tooth rubber layer formed on the inner circumference side of the belt relative to the core wire, A toothed belt in which the inner surface of the belt is made of toothed fabric, The aforementioned tooth cloth consists of a cloth and an impregnating component impregnated into the cloth. The aforementioned impregnation component is a toothed belt containing conductive carbon black.

12. The toothed belt according to claim 10 or 11, wherein the conductive carbon black is conductive carbon black derived from a conductive dispersion containing conductive carbon black, and the proportion of solids in the conductive dispersion is 0.1 to 10 parts by mass per 100 parts by mass of the cloth.

13. The toothed belt according to any one of claims 10 to 12, wherein the back portion and the tooth rubber layer do not contain conductive additives.

14. The electrical resistance value R of the belt tooth surface, measured according to the method compliant with ISO 9563 (2015), is 6 × 10 ５ A toothed belt according to any one of claims 10 to 13, wherein the ratio × L / W (Ω) [where L is the distance between electrodes (mm) and W is the width of the electrodes (mm) (however, if the width of the belt is smaller than the width of the electrodes, the width of the belt)] is less than or equal to × L / W (Ω).

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