Toothed belt, and method for manufacturing a toothed belt

Abstract

To provide a toothed belt that minimizes debris scattering during operation. [Solution] A toothed belt comprising: a belt body having a plurality of teeth provided at a constant pitch on the inner circumference of the belt; a core wire embedded in the belt body; and a tooth cloth provided on the inner circumference side of the belt body to cover the plurality of teeth, wherein the tooth cloth comprises a tooth cloth body made of woven, knitted or nonwoven fabric, and a crosslinked material of an uncrosslinked rubber composition impregnated on the inner circumference side of the tooth cloth body, wherein the uncrosslinked rubber composition comprises an uncrosslinked rubber component and a friction coefficient reducing agent, the content of the friction coefficient reducing agent is 130 parts by mass or more and 200 parts by mass or less per 100 parts by mass of the rubber component, and the rubber component is at least one selected from hydrogenated nitrile rubber (H-NBR), ethylene propylene diene rubber (EPDM), and chloroprene rubber (CR).

Description

Technical Field

[0001] The present invention relates to a toothed belt and a method for manufacturing the toothed belt.

Background Art

[0002] As a toothed belt, for example, a toothed belt in which belt teeth are coated with cloth is known (for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] A toothed belt is used, for example, as a power transmission means for industrial robots. A toothed belt used for industrial robots, like those used in other machines, is required to have high synchronization performance and high reliability. In addition, suppression of flying objects due to running is required.

[0005] As a characteristic movement of a toothed belt used for industrial robots, it can be cited that forward and reverse rotations are repeated at a high cycle. In a toothed belt that moves in such a manner, when the belt runs, the belt teeth move in the pulley groove, and the contact portion with the pulley is strongly slid, which may accelerate the wear of the belt teeth and increase flying objects. When such flying objects occur, although it does not have a great impact on the durability of the toothed belt, there is a possibility that the flying objects may cause malfunction of the surrounding sensors.

Means for Solving the Problems

[0006] An object of the present invention is to provide a toothed belt with few flying objects during belt running and suitable for use in industrial robots.

[0007] A toothed belt according to one aspect of the present invention is A belt body having multiple teeth arranged at a constant pitch on the inner circumference of the belt, The core wire embedded in the belt body mentioned above, A tooth cloth covering the multiple teeth is provided on the inner circumference side of the belt body, Equipped with, The tooth cloth described above comprises a tooth cloth body made of woven, knitted, or nonwoven fabric, and a crosslinked material of an uncrosslinked rubber composition impregnated into the inner circumference of the belt of the tooth cloth body. The above uncrosslinked rubber composition comprises an uncrosslinked rubber component and a friction coefficient reducing agent, and the content of the friction coefficient reducing agent is 130 parts by mass or more and 200 parts by mass or less per 100 parts by mass of the rubber component. The above rubber component is at least one selected from hydrogenated nitrile rubber (H-NBR), ethylene propylene diene rubber (EPDM), and chloroprene rubber (CR).

[0008] A method for manufacturing a toothed belt according to one aspect of the present invention is a method for manufacturing a toothed belt using a pre-prepared uncrosslinked rubber composition for making a belt body, a core wire, and an uncrosslinked tooth fabric, The process of preparing the uncrosslinked tooth cloth described above is: (a) A step of immersing a tooth cloth body, which is made of woven, knitted or nonwoven fabric, in a treatment solution containing an uncrosslinked rubber component, a friction coefficient reducing agent and a solvent, (b) After removing the tooth cloth body from the processing solution, the heating step includes removing the solvent, The above rubber component is at least one selected from hydrogenated nitrile rubber (H-NBR), ethylene propylene diene rubber (EPDM), and chloroprene rubber (CR). [Effects of the Invention]

[0009] According to the present invention, a toothed belt with minimal scattering of debris during belt operation can be provided. [Brief explanation of the drawing]

[0010] [Figure 1] FIG. 1 is a perspective view showing an example of a toothed belt. [Figure 2] FIG. 2 is a sectional view taken along line A-A of FIG. 1. [Figure 3A] FIG. 3A is an end view taken along line B-B of FIG. 1. [Figure 3B] FIG. 3B is a partial enlarged view of FIG. 3A. [Figure 4] FIG. 4 is a diagram for explaining a method of manufacturing a toothed belt. [Figure 5] FIG. 5 is a diagram for explaining a method of manufacturing a toothed belt. [Figure 6] FIG. 6 is a diagram for explaining a method of manufacturing a toothed belt. [Figure 7] FIG. 7 is a diagram for explaining the dimensions of the toothed belts manufactured in the examples and comparative examples. [Figure 8] FIG. 8 is a diagram showing a testing machine employed in belt running test A. [Figure 9] FIG. 9 is a diagram showing a cycle pattern in belt running test A. [Figure 10] FIG. 10 is a diagram showing a binary image obtained in belt running test A. [Figure 11] FIG. 11 is a diagram showing a pulley layout employed in belt running test B.

MODE FOR CARRYING OUT THE INVENTION

[0011] The outline of the embodiments of the present invention will be listed and described. (1) A belt body having a plurality of tooth portions provided at a constant pitch on the inner circumference of the belt, A core wire embedded in the belt body, A tooth cloth provided on the inner circumferential side of the belt body and covering the plurality of tooth portions, Comprising: The tooth cloth has a tooth cloth body made of a woven fabric, a knitted fabric or a non-woven fabric, and a cross-linked product of an uncross-linked rubber composition impregnated on the inner circumferential side of the belt body of the tooth cloth body. The above unvulcanized rubber composition contains an unvulcanized rubber component and a coefficient-of-friction reducing agent, and the content of the coefficient-of-friction reducing agent is 130 parts by mass or more and 200 parts by mass or less with respect to 100 parts by mass of the rubber component. The rubber component is at least one selected from hydrogenated nitrile rubber (H-NBR), ethylene propylene diene rubber (EPDM), and chloroprene rubber (CR), a toothed belt.

[0012] The toothed belt can increase the convergence of the fibers constituting the toothed fabric to suppress the distortion of the toothed fabric and can reduce the coefficient of friction. Therefore, even during belt running at a high speed cycle, wear of the teeth is less likely to progress. Therefore, according to the toothed belt, generation of flying objects during belt running can be reduced.

[0013] (2) In the toothed belt according to (1) above, a preferred coefficient-of-friction reducing agent is PTFE particles having an average particle diameter of 10 μm or less.

[0014] (3) In the toothed belt according to (1) or (2) above, a preferred unvulcanized rubber composition contains H-NBR as the rubber component and further contains an unsaturated carboxylic acid metal salt.

[0015] (4) In the toothed belt according to any one of (1) to (3) above, a preferred tooth pitch is 3 mm or more and 5 mm or less.

[0016] (5) In the toothed belt according to any one of (1) to (4) above, a preferred toothed belt has an inner peripheral surface formed of the toothed fabric, and the toothed fabric main body and a crosslinked product of the unvulcanized rubber composition are exposed on the inner peripheral surface.

[0017] (6) A method for manufacturing a toothed belt using an unvulcanized rubber composition for producing a belt main body, a core wire, and an unvulcanized toothed fabric prepared in advance, The step of preparing the unvulcanized toothed fabric is (a) A step of immersing a toothed fabric main body composed of a woven fabric, a knitted fabric, or a non-woven fabric in a treatment liquid containing an unvulcanized rubber component, a coefficient-of-friction reducing agent, and a solvent, and (b) After removing the tooth cloth body from the processing solution, the heating step includes removing the solvent, A method for manufacturing a toothed belt, wherein the rubber component is at least one selected from hydrogenated nitrile rubber (H-NBR), ethylene propylene diene rubber (EPDM), and chloroprene rubber (CR).

[0018] According to the above-described method for manufacturing a toothed belt, the above-described toothed belt can be manufactured.

[0019] (7) In the method for manufacturing a toothed belt as described in (6) above, the preferred content of the friction coefficient reducing agent in the processing liquid is 130 parts by mass or more and 200 parts by mass or less per 100 parts by mass of the rubber component.

[0020] (8) In the method for manufacturing a toothed belt described in (6) or (7) above, the preferred treatment liquid contains H-NBR as the rubber component and further contains an unsaturated carboxylic acid metal salt.

[0021] Embodiments of the present invention will be described in detail below with reference to the drawings. The present invention is not limited to these embodiments.

[0022] (Toothed belt) Figure 1 is a perspective view showing a part of a toothed belt 1 according to an embodiment of the present invention. Figure 2 is a cross-sectional view taken along line AA in Figure 1. Figure 3A is an end view of line BB in Figure 1. Figure 3B is a magnified view of a portion of Figure 3A. Figure 3B shows a magnified view of the area around region E in Figure 3A. The toothed belt 1 is an example of an embodiment of the present invention. The toothed belt 1 is used, for example, to drive a robot arm. Figure 1 shows a portion of the toothed belt 1. The toothed belt 1 is an endless interlocking transmission belt. The toothed belt 1 is a single-sided toothed belt.

[0023] In Figure 1, the direction indicated by the double-headed arrow X is the width direction of the toothed belt 1. The direction indicated by the double-headed arrow Y is the length direction of the toothed belt 1. The length direction is also the circumferential direction of the toothed belt 1. The direction indicated by the double-headed arrow Z is the thickness direction of the toothed belt 1. The upper side of each plane is the outer circumference of the toothed belt 1, and the lower side is the inner circumference.

[0024] The belt length of toothed belt 1 (belt length in the belt pitch line) is, for example, 200 mm or more and 2000 mm or less. The belt width Wb of the toothed belt 1 is, for example, 4 mm or more and 30 mm or less. The belt thickness Tb of the toothed belt 1 is, for example, 3.0 mm or more and 4.0 mm or less. The belt thickness Tb of the toothed belt 1 is the thickness of the thickest part of the toothed belt 1. The dimensions of the toothed belt according to the embodiment of the present invention are not limited to this range.

[0025] The toothed belt 1 has a back portion 11 and a plurality of belt teeth 12. The back portion 11 extends in the circumferential direction of the belt. The back portion 11 is an endless band. In a cross-section perpendicular to the circumferential direction of the toothed belt 1, the cross-sectional shape of the back portion 11 is rectangular. Multiple belt teeth 12 are provided on the inner circumference side of the back portion 11. The multiple belt teeth 12 are arranged at equal intervals in the circumferential direction of the belt. Each belt tooth 12 extends in the belt width direction. The portion sandwiched between adjacent belt teeth 12 is the tooth root.

[0026] The tooth pitch Pb of the toothed belt 1 is, for example, 3 mm or more and 5 mm or less. In the toothed belt 1, the nominal pitch of the belt teeth 12 is preferably 3 mm or 5 mm. Here, "nominal pitch" has the same meaning as "nominal pitch" as used in JIS B 1857-1, etc. In the embodiment of the present invention, the range of the tooth pitch Pb of the toothed belt 1 is 3 ± 0.05 mm when the nominal pitch is 3 mm, and 5 ± 0.05 mm when the nominal pitch is 5 mm. The tooth profile of the belt teeth 12 is, for example, an arc tooth profile.

[0027] The toothed belt 1 comprises a belt body 2, a core wire 3, and a toothed fabric 4. The belt body 2 has a strip-like shape. The belt body 2 comprises a base portion 21 and a plurality of teeth portions 22. The base portion 21 extends in the circumferential direction of the belt. The core wire 3 is embedded in the base portion 21. Multiple teeth 22 are provided on the inner circumferential side of the base portion 21. Multiple teeth 22 are integral with the base portion 21. Multiple teeth 22 are arranged at equal intervals in the circumferential direction of the belt. The surface of the teeth 22 is covered with tooth cloth 4.

[0028] The tooth fabric 4 is provided on the inner circumference side of the toothed belt 1. The inner circumferential surface of the toothed belt 1 is made up of the tooth fabric 4. The inner circumferential surface of the toothed belt 1 is the surface of the tooth fabric 4. The tooth cloth 4 comprises a tooth cloth body 41 and a crosslinked material 42 of an uncrosslinked rubber composition impregnated into the tooth cloth body 41.

[0029] The belt body 2 is composed of a crosslinked rubber composition, for example, a crosslinked product of the uncrosslinked rubber composition A. In this specification, the crosslinked rubber composition constituting the belt body is also referred to as the belt body rubber. The belt body 2 consists of a base portion 21 and a tooth portion 22, both made of belt body rubber. In the toothed belt 1 shown in Figure 1, the base 21 and the teeth 22 are made of the same belt body rubber. The belt body rubber constituting the base 21 and the belt body rubber constituting the teeth 22 may have different compositions.

[0030] The belt body rubber constituting the belt body 2 (base portion 21 and tooth portion 22) is a crosslinked product of uncrosslinked rubber composition A, which contains uncrosslinked rubber components and rubber compounding agents. Examples of rubber components included in the above-mentioned uncrosslinked rubber composition A include hydrogenated nitrile rubber (H-NBR), ethylene propylene diene rubber (EPDM), and chloroprene rubber (CR). These may be used individually or in combination of two or more types.

[0031] The toothed belt 1 may be used, for example, as a toothed belt for driving a robot arm in a robot used in a harsh environment unsuitable for human activity. In this case, the belt body 2 of the toothed belt 1 may be required to have heat resistance, oil resistance, and weather resistance. From this viewpoint, it is preferable that the rubber component contains H-NBR.

[0032] The amount of acrylonitrile bound to H-NBR in the above uncrosslinked rubber composition A is preferably 20% by mass or more and 50% by mass or less. The iodine value of the above H-NBR is preferably 5 mg / 100 mg or more and 15 mg / 100 mg or less. The Mooney viscosity of the above H-NBR at 100°C is preferably 30 ml 1+4 (100°C) or more and 90 ml 1+4 (100°C) or less. If the above-mentioned uncrosslinked rubber composition A contains H-NBR, it is preferable that the above-mentioned uncrosslinked rubber composition A contains an unsaturated carboxylic acid metal salt together with H-NBR.

[0033] Examples of the rubber compounding agents mentioned above include vulcanization accelerators, antioxidants, reinforcing agents, plasticizers, co-crosslinking agents, crosslinking agents, and processing aids.

[0034] Examples of the above-mentioned vulcanization accelerators include metal oxides, metal carbonates, fatty acids, and their derivatives. Examples of the above-mentioned metal oxides include zinc oxide (zinc oxide) and magnesium oxide. These vulcanization accelerators may be used individually or in combination of two or more types. The amount of the above-mentioned vulcanization accelerator is, for example, 3 parts by mass or more and 15 parts by mass or less per 100 parts by mass of the rubber component.

[0035] Examples of the above-mentioned anti-aging agents include benzimidazole-based anti-aging agents, aromatic secondary amine-based anti-aging agents, and amine-ketone-based anti-aging agents. These anti-aging agents may be used individually or in combination of two or more types. As the above-mentioned anti-aging agent, it is preferable to use a combination of a benzimidazole-based anti-aging agent and an aromatic secondary amine-based anti-aging agent. The amount of the above-mentioned anti-aging agent is, for example, 1.5 parts by mass or more and 4.5 parts by mass or less per 100 parts by mass of the rubber component.

[0036] Examples of the reinforcing materials mentioned above include carbon black and silica. The reinforcing materials may also include carbon black and silica in combination. Examples of the carbon blacks mentioned above include channel black, furnace black, thermal black, and acetylene black. Examples of furnace blacks mentioned above include SAF, ISAF, N-339, HAF, N-351, MAF, FEF, SRF, GPF, ECF, and N-234. Examples of the above-mentioned thermal blacks include FT and MT. You may use only one type of carbon black, or you may use two or more types in combination. When the above carbon black is used, it is preferable that at least FEF or HAF is used.

[0037] When carbon black is used, its content is, for example, 10 parts by mass or more and 100 parts by mass or less per 100 parts by mass of rubber component. In this case, the preferred carbon black content is 45 parts by mass or more and 85 parts by mass or less per 100 parts by mass of rubber component. When silica is used, its content is, for example, 10 parts by mass or more and 80 parts by mass or less per 100 parts by mass of rubber component.

[0038] Examples of the plasticizers mentioned above include dialkyl sebacate, dialkyl phthalate, and dialkyl adipate. Examples of the above-mentioned dialkyl sebacates include polyether esters and dioctyl sebacate (DOS). Examples of the above-mentioned dialkyl phthalates include dibutyl phthalate (DBP) and dioctyl phthalate (DOP). Examples of the above-mentioned dialkyl adipates include dioctyl adipate (DOA). These plasticizers may be used individually or in combination of two or more types. When the above plasticizer is used, it is preferable that at least a polyether ester is used. The content of the plasticizer is, for example, 5 parts by mass or more and 15 parts by mass or less per 100 parts by mass of rubber component.

[0039] Examples of the above-mentioned co-crosslinking agents include trimethylolpropane trimethacrylate, m-phenylenedimaleimide, zinc dimethacrylate, and triallyl isocyanurate. These co-crosslinking agents may be used individually or in combination of two or more. The content of the above-mentioned co-crosslinking agent is, for example, 3 parts by mass or more and 8 parts by mass or less per 100 parts by mass of the rubber component.

[0040] Examples of the crosslinking agents mentioned above include sulfur and organic peroxides. Sulfur and organic peroxides may be used in combination. Of course, either one may be used alone. When sulfur and organic peroxide are used in combination as the crosslinking agent, it is preferable that the total amount of the crosslinking agent is, for example, 0.1 parts by mass or more and 0.7 parts by mass or less of sulfur and 1 part by mass or more and 5 parts by mass or less of organic peroxide per 100 parts by mass of rubber component. When only organic peroxides are used as the crosslinking agent, the amount of organic peroxides used is, for example, 2 parts by mass or more and 10 parts by mass or less per 100 parts by mass of rubber components.

[0041] Examples of the processing aids mentioned above include stearic acid, polyethylene wax, and metal salts of fatty acids. These processing aids may be used individually or in combination of two or more types. The content of the above processing aid is, for example, 0.5 parts by mass or more and 2 parts by mass or less per 100 parts by mass of rubber component.

[0042] The core wire 3 is embedded in the base 21. The core wire 3 has a pitch in the belt width direction and is arranged to form a spiral.

[0043] The core wire 3 preferably contains carbon fibers as a constituent material. The core wire 3 may consist solely of carbon fibers, or it may consist of carbon fibers and other types of fibers. The carbon fibers mentioned above may be PAN-based carbon fibers or pitch-based carbon fibers. The carbon fibers mentioned above may also contain both PAN-based and pitch-based carbon fibers. The carbon fibers mentioned above may also have a sizing agent such as epoxy resin attached to them.

[0044] Other types of fibers mentioned above include, for example, inorganic fibers, organic fibers, and metallic fibers. Examples of the inorganic fibers mentioned above include glass fibers. Examples of the above-mentioned organic fibers include aramid fibers, polyester fibers, PBO fibers, nylon fibers, and polyketone fibers.

[0045] When the core wire 3 is composed of carbon fibers and other types of fibers, the proportion of carbon fibers to all fibers is preferably 50% by mass or more. The higher the proportion of carbon fibers, the better, and 90% by mass or more is particularly preferred.

[0046] The core wire 3, which uses the aforementioned fibers, is a twisted yarn. The twisting method of the core wire 3 is single-twist, double-twist, or Lang twist. Single-twist is preferred for the core wire 3. When the core wire 3 is a single-twist yarn, it is easier to ensure good bending fatigue resistance. Furthermore, since the core wire 3 made of a single-twist yarn has sufficient strength and elastic modulus, it is suitable for providing a toothed belt 1 with excellent positioning performance. From the viewpoint of the bonding treatment of the filaments constituting the core wire 3 (from the viewpoint of making it easier for adhesive components to be impregnated into the interior), a single-stranded core wire 3 is preferable.

[0047] When the core wire 3 is a single-twist yarn, the preferred number of single twists per 10 cm is between 4 and 10. If the number of single twists is less than 4 per 10 cm, it may not have sufficient bending fatigue resistance. On the other hand, if the number of single twists exceeds 10 per 10 cm, the strength and elastic modulus of the core wire will decrease, and toothed belts using this core wire may have poor positioning capabilities.

[0048] When the core wire 3 is a multi-ply yarn or a Lang-ply yarn, the preferred number of top twists per 10 cm is 4 to 8. If the number of top twists is less than 4 per 10 cm, it may not have sufficient bending fatigue resistance. On the other hand, if the number of top twists exceeds 8 per 10 cm, the strength and elastic modulus of the core wire will decrease, and toothed belts using this core wire may have poor positioning. When the core wire 3 is double-twisted or Lang-twisted, the number of under-twist turns per 10 cm is not particularly limited, but for example, it is between 6 and 12 turns.

[0049] The core wire 3 is preferably a core wire made solely of carbon fibers (hereinafter also referred to as a carbon core wire). The carbon core wire described above is a twisted yarn made by twisting together carbon filaments, which are filaments made of carbon fibers. The carbon core wires described above are preferably twisted in a single-sided configuration.

[0050] In the carbon core wire described above, the filament diameter of the carbon filament is preferably 4 μm or more and 6 μm or less. In the carbon core wire described above, the number of carbon filaments is preferably 5,000 or more and 7,000 or less. A toothed belt 1 using a carbon core wire with such a configuration has better positioning performance.

[0051] In the toothed belt 1, the core wire 3 may be an S-twisted yarn (a multi-twisted yarn, or Lang-twisted yarn, in which the upper twist direction is the S direction), or a Z-twisted yarn (a multi-twisted yarn, or Lang-twisted yarn, in which the upper twist direction is the Z direction), or both S-twisted yarn and Z-twisted yarn may be used. From the viewpoint of minimizing shifting during belt operation, it is preferable that the core wires 3 be arranged such that S-twisted core wires 3 and Z-twisted core wires 3 are positioned alternately with a pitch in the belt width direction.

[0052] If the core wire 3 contains carbon fiber as a constituent material, the core wire diameter of the core wire 3 is, for example, 0.50 mm or more and 0.60 mm or less. Also, the pitch of the core wires 3 (distance between the centers of adjacent core wires in the belt width direction) is, for example, 0.70 mm or more and 0.85 mm or less. A toothed belt 1 whose core wire diameter and pitch satisfy these conditions has low bending rigidity and good positioning capabilities. Furthermore, this toothed belt 1 is also suitable for ensuring good responsiveness.

[0053] If the core wire 3 is a core wire that contains carbon fibers as a constituent material that can secure sufficient tension even when thin, it is possible to make the core wire diameter thin, between 0.50 mm and 0.60 mm, while narrowing the core wire arrangement pitch to between 0.70 mm and 0.85 mm. Therefore, a toothed belt 1 using a core wire 3 containing carbon fibers as a constituent material has excellent positioning capabilities, even if it is a relatively small toothed belt.

[0054] The core wire 3 may be treated with an adhesive to enhance its adhesion to the belt body 2. Examples of the bonding treatments mentioned above include RFL treatment, which involves immersion in an RFL aqueous solution followed by heating, and rubber cement treatment, which involves immersion in rubber cement followed by drying. These bonding treatments may be performed individually or in combination.

[0055] The above bonding treatment may also involve immersing the rubber latex in an aqueous treatment agent containing a crosslinking agent, followed by drying. The above aqueous treatment agent mainly consists of rubber latex. Examples of rubber latex include those containing at least one of nitrile rubber, hydrogenated nitrile rubber, carboxyl-modified nitrile rubber, and carboxyl-modified hydrogenated nitrile rubber as rubber components. The above aqueous treatment agent may also contain RFL condensate.

[0056] The core wire 3 may be subjected to a surface treatment before the above-mentioned bonding treatment. Examples of such surface treatments include immersion in an epoxy solution or an isocyanate solution followed by heating. These bonding and surface preparation processes are carried out before winding the core wire onto the mold in the toothed belt manufacturing method described later.

[0057] The tooth fabric 4 covers the surface of the teeth 22. The tooth fabric 4 constitutes the inner circumferential surface of the toothed belt 1. The inner circumferential surface of the toothed belt 1 includes the tooth fabric 4. As shown in Figure 3B, the tooth cloth 4 comprises a tooth cloth body 41 and a crosslinked rubber composition 42 which is a crosslinked product of the uncrosslinked rubber composition B impregnated into the tooth cloth body 41. In this specification, the crosslinked product of the uncrosslinked rubber composition B impregnated into the tooth cloth is also referred to as the tooth cloth impregnated rubber 42. The tooth cloth body 41 shown in Figure 3B is made of woven fabric. In embodiments of the present invention, the tooth cloth body may be made of knitted fabric or nonwoven fabric. The tooth cloth body 41 is a component made of fibers and has gaps that can be filled with tooth cloth impregnated rubber 42.

[0058] Examples of fibers that make up the tooth cloth body 41 include polyamide fibers (nylon fibers), polyester fibers, aramid fibers, poly(p-phenylenebenzobisoxazole) (PBO) fibers, cotton, and the like. For the tooth cloth body 41, a woven fabric of polyamide fibers is preferred, for example. The thickness of the tooth cloth body 41 is, for example, 0.5 mm or more and 1.2 mm or less. The tooth fabric body 41 preferably has elasticity, such as a woven fabric in which the weft threads have been treated with a woolly finish.

[0059] In the tooth fabric body 41, gaps exist between the fibers (including RFL-treated fibers) that make up the tooth fabric body 41. The tooth cloth 4 has tooth cloth impregnated rubber 42 that fills these gaps. This tooth cloth impregnated rubber is provided, for example, by impregnating the tooth cloth body 41 with an impregnation treatment liquid containing an uncrosslinked rubber composition B, and then subjecting it to a heat treatment at a temperature at which the rubber components crosslink.

[0060] In the tooth fabric 4, the tooth fabric impregnated rubber 42 refers to the crosslinked material of the uncrosslinked rubber composition B that has penetrated into the tooth fabric body 41. The tooth fabric impregnated rubber 42 is impregnated at least on the inner circumference side of the belt of the tooth fabric 4. The tooth fabric impregnated rubber 42 may be impregnated into almost the entire tooth fabric 4.

[0061] In embodiments of the present invention, the impregnation of the tooth fabric 4 with the tooth fabric-impregnating rubber 42 on the inner circumference side of the belt means that the tooth fabric-impregnating rubber 42 is impregnated in the region of the tooth fabric 4 on the inner circumference side of the belt from the center in the thickness direction. At this time, the tooth fabric impregnation rubber 42 may be impregnated into the entire area on the inner circumference side of the belt from the center in the thickness direction of the tooth fabric 4, but usually the tooth fabric impregnation rubber 42 is impregnated into the tooth fabric body 41 so that some gaps remain.

[0062] In the region on the inner circumference side of the belt from the center in the thickness direction of the tooth fabric 4, the preferred ratio of tooth fabric impregnated rubber 42 to the sum of tooth fabric body 41 and tooth fabric impregnated rubber 42 is 25% to 35%. In this case, it is suitable for suppressing the generation of scattered debris. The ratio of the tooth fabric impregnated rubber 42 to the total area of ​​the tooth fabric body 41 and the tooth fabric impregnated rubber 42 is calculated by microscopic observation of a cross-section along the thickness direction of the tooth fabric 4 and expressing it as the ratio (%) of the area of ​​the tooth fabric impregnated rubber to the total area of ​​the tooth fabric body and the tooth fabric impregnated rubber.

[0063] In the toothed belt 1, a portion of the toothed fabric impregnated rubber 42 may be exposed to a portion of the surface (inner circumferential surface of the toothed belt 1) 4a of the toothed fabric 4. In this case, when the inner circumferential surface of the toothed belt 1 is observed, the toothed fabric impregnated rubber 42 can be seen on a portion of the surface 4a of the toothed fabric 4.

[0064] As described above, in tooth cloth 4, the tooth cloth impregnation rubber 42 is embedded in the gaps between the fibers of the tooth cloth body 41. Furthermore, the tooth cloth impregnation rubber 42 is exposed on a portion of the surface 4a of tooth cloth 4. In this case, the inner circumferential surface of the toothed belt 1 is made of toothed fabric 4, and the toothed fabric body 41 and the toothed fabric impregnated rubber 42 are exposed on the inner circumferential surface of the toothed belt 1.

[0065] The uncrosslinked rubber composition B, which is crosslinked to become the tooth cloth impregnated rubber 42, contains an uncrosslinked rubber component and a friction coefficient reducing agent. The above rubber component is at least one selected from hydrogenated nitrile rubber (H-NBR), ethylene propylene diene rubber (EPDM), and chloroprene rubber (CR). These rubber components readily form crosslinked materials with high elastic modulus and are suitable for suppressing the generation of airborne particles. Among these, hydrogenated nitrile rubber (H-NBR) is preferred.

[0066] The above rubber component is preferably the same type of rubber component used in the belt body rubber that constitutes the belt body 2. If the base portion 21 and the tooth portion 22 that constitute the belt body are made of different types of belt body rubber, it is preferable that the rubber component is the same type of rubber component used in the belt body rubber that constitutes the tooth portion 22.

[0067] Examples of the friction-reducing agents mentioned above include particles made of fluorine-based resins such as tetrafluoroethylene resin (hereinafter also referred to as PTFE), perfluoroalkoxy resin, fluoroethylene propylene resin, tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer resin, tetrafluoroethylene-ethylene copolymer resin, trifluorochloroethylene resin, and vinylidene fluoride resin, as well as ultra-high molecular weight polyethylene, poly(meth)acrylic acid ester, and silicone-acrylic copolymer. These may be used individually or in combination of two or more. Among these, PTFE particles, which have a high proportion of fluorine atoms and a large friction coefficient reduction effect, are preferred.

[0068] The average particle size of the friction-reducing agent is preferably 10 μm or less. In this case, the friction-reducing agent can easily penetrate into the interior of the tooth cloth body. The average particle size of the above-mentioned low-friction coefficient agent was measured using a laser diffraction type particle size distribution analyzer.

[0069] The amount of the friction-reducing agent is 130 parts by mass or more and 200 parts by mass or less per 100 parts by mass of the rubber component. If the content of the above-mentioned friction-reducing agent is less than 130 parts by mass, the amount of wear dust generated during belt operation increases, and the scattering of debris cannot be adequately suppressed. Furthermore, durability tends to be inferior. If the amount of the above-mentioned friction-reducing agent exceeds 200 parts by mass, the tooth cloth impregnated rubber becomes brittle, and the amount of rubber scattered during belt operation increases. The amount of the friction-reducing agent is preferably 140 parts by mass or more and 200 parts by mass or less per 100 parts by mass of the rubber component.

[0070] The above-mentioned uncrosslinked rubber composition B may contain components other than rubber components and friction coefficient reducing agents. Other components include, for example, vulcanization accelerators, antioxidants, reinforcing agents, plasticizers, co-crosslinking agents, crosslinking agents, and processing aids. Specific examples of these include, for instance, the same components as those exemplified as components that may be included in the uncrosslinked rubber composition A described above.

[0071] In the case where the rubber component of the uncrosslinked rubber composition B is hydrogenated nitrile rubber (H-NBR), it is preferable that the uncrosslinked rubber composition B further contains an unsaturated carboxylic acid metal salt. Examples of the above-mentioned unsaturated carboxylic acids include methacrylic acid and acrylic acid. Examples of the above-mentioned metals include zinc, calcium, magnesium, and aluminum. As the above unsaturated carboxylate metal salts, zinc methacrylate and zinc acrylate are preferred.

[0072] When the uncrosslinked rubber composition B contains uncrosslinked hydrogenated nitrile rubber (H-NBR) and an unsaturated carboxylic acid metal salt, the ratio of the two is, for example, 80 to 120 parts by mass of the unsaturated carboxylic acid metal salt per 100 parts by mass of uncrosslinked hydrogenated nitrile rubber.

[0073] In the toothed belt 1, the tooth fabric-impregnated rubber 42 is exposed on a portion of the surface of the tooth fabric 4 (the inner circumferential surface of the belt teeth 12). In this case, the occupancy rate (percentage of occupied area) of the tooth fabric-impregnated rubber 42 on the surface of the tooth fabric 4 is preferably 5% or more and 15% or less. In this case, it is suitable for increasing the binding strength of the fibers constituting the tooth fabric body 41 and suppressing the generation of scattered debris. If the proportion of the tooth fabric-impregnated rubber 42 is less than 5%, the binding properties of the fibers are poor, and flying debris is more likely to be generated. On the other hand, if the proportion of the tooth fabric-impregnated rubber 42 exceeds 15%, the tooth fabric-impregnated rubber 42 itself becomes a source of flying debris, which may increase the amount of flying debris generated.

[0074] The occupancy rate of the toothed fabric-impregnated rubber 42 is calculated by obtaining an enlarged image (magnification 200x) of the tooth tip surface of the belt teeth 12 of the toothed belt 1, and using this image to calculate the occupancy rate (%) of the area where the toothed fabric-impregnated rubber 42 is present relative to the area of ​​the inner circumferential surface of the toothed belt 1.

[0075] The tooth cloth 4 may also be RFL treated. The RFL treatment is performed before the tooth cloth impregnation rubber is provided. Applying RFL treatment improves the adhesion between the tooth cloth body 41 and the tooth cloth impregnated rubber 42. Furthermore, if a coating layer 43, described later, is provided, the adhesion between the tooth cloth body 41 and the coating layer 43 is also improved. RFL processing can be performed using conventionally known methods.

[0076] In the toothed belt 1, a coating layer 43 (see Figure 3B) is laminated on the belt body 2 side of the tooth fabric 4. The coating layer 43 is a layer provided on the back side of the belt of the tooth cloth body 41. By providing the coating layer 43, the adhesion between the tooth fabric 4 and the belt body 2 is improved.

[0077] The coating layer 43 consists of a crosslinked product of the uncrosslinked rubber composition C. An example of the uncrosslinked rubber composition C for providing the coating layer 43 is a composition obtained by removing the friction coefficient reducing agent from the uncrosslinked rubber composition B described above for providing the tooth cloth impregnated rubber 42.

[0078] In the toothed belt 1, the belt body 2, which is made of the cross-linked rubber composition described above, has teeth 22 with a JIS A hardness of 84A or more and 98A or less. In this case, the belt body 2 is less prone to deformation, and damage to the teeth 22 due to cracking is less likely to occur. The JIS A hardness of the teeth 22 is measured by pressing a rubber hardness tester perpendicularly against the side surface of the teeth 22 on the belt body 2 (the end face of the teeth 22 in the belt width direction). A Type A durometer specified in JIS-K6253-3 (2012) is used as the rubber hardness tester. The ambient temperature during measurement is 23°C.

[0079] (Manufacturing method for toothed belts) Figures 4 to 6 are diagrams illustrating the manufacturing method of the toothed belt 1. Figures 4 to 6 show only the mold 5 for belt forming and a portion of the belt (including the belt material).

[0080] In the manufacture of the toothed belt 1, a belt molding die 5 is used. The mold 5 is cylindrical. The outer circumference of the mold 5 is provided with recesses 51 extending in the axial direction and protrusions 52 extending in the axial direction. The recesses 51 have a cross-sectional shape corresponding to the belt teeth 12 and are grooves extending in the axial direction (the direction perpendicular to the plane of the paper in Figure 5). The recesses 51 are provided at regular intervals in the circumferential direction. The protrusions 52 are provided between adjacent recesses 51.

[0081] (1) Prepare the materials. Prepare the uncrosslinked rubber sheet 23. An uncrosslinked rubber composition A is obtained by kneading the rubber components and then adding and kneading the rubber compounding agent. An uncrosslinked rubber sheet 23 is produced by molding the obtained uncrosslinked rubber composition A. At this time, a method such as calendering can be used to mold the uncrosslinked rubber sheet 23.

[0082] Prepare core wire 3. The core wire 3 is subjected to adhesive treatment and surface preparation as needed.

[0083] Prepare an uncrosslinked tooth cloth 24. The tooth cloth is prepared, for example, by the following method. Furthermore, the prepared tooth cloth 4 is formed into a cylindrical shape.

[0084] The preparation of the uncrosslinked tooth cloth 24 involves, for example, (A) RFL treatment, (B) impregnation treatment, and (C) coating treatment. In embodiments of the present invention, step (B) is an essential step, and steps (A) and (C) are optional steps. The following are examples of the steps involved in each process.

[0085] (A) Prepare a fibrous material consisting of a woven, knitted, or nonwoven fabric, and subject this fibrous material to RFL treatment (resorcinol-formaldehyde-rubber latex treatment) using a conventionally known method. Specifically, the fibrous material is immersed in a predetermined RFL treatment solution, and then subjected to heat treatment. This yields the tooth cloth body. This step (A) may be omitted, in which case the tooth cloth body will consist only of fiber material.

[0086] (B) The rubber component is kneaded, and then a friction coefficient reducing agent and other additives added as needed are added and kneaded to obtain an uncrosslinked rubber composition B. Furthermore, a solvent such as methyl ethyl ketone or toluene is added to the obtained uncrosslinked rubber composition B to prepare an impregnation treatment solution containing the uncrosslinked rubber composition B. In preparing the above impregnation treatment solution, the addition of the solvent can be carried out at various timings, for example, in the middle of the process to obtain the uncrosslinked rubber composition B. The tooth cloth body is immersed in this impregnation solution to allow the solution to penetrate the tooth cloth body. Then, the tooth cloth body is passed between a pair of pressure rolls to allow the impregnation solution to adhere to the tooth cloth body and remove any excess impregnation solution. Next, a drying process (heating process) is performed to remove the solvent contained in the impregnation solution that has adhered to the tooth cloth body. The conditions for this drying process can be appropriately determined considering the composition of the impregnation solution, and it is preferable that the solvent is removed and the rubber components are not crosslinked.

[0087] The amount of solvent contained in the impregnation treatment liquid is preferably 450 parts by mass or more and 550 parts by mass or less per 100 parts by mass of the uncrosslinked rubber composition B. An impregnation treatment liquid containing such an amount of solvent has low viscosity and easily penetrates into the interior of the tooth cloth body. Furthermore, the occupancy rate of the tooth cloth impregnated rubber can be adjusted by adjusting the amount of solvent.

[0088] In this step (B), the occupancy rate of the tooth fabric impregnation rubber in the finished tooth fabric 4 can be adjusted by adjusting the gap size (nip pressure) between the pair of pressure rolls. Here, narrowing the gap size between the pair of pressure rolls can reduce the occupancy rate of the tooth fabric impregnation rubber, while widening the gap size can increase the occupancy rate of the tooth fabric impregnation rubber.

[0089] (C) First, a high-viscosity coating rubber is prepared. Specifically, the rubber components are kneaded, and other additives are added as needed and kneaded to produce an uncrosslinked rubber composition C. A solvent such as methyl ethyl ketone or toluene is added as needed to prepare the coating rubber. In the preparation of the coating rubber described above, the addition of the solvent can be done at various timings, for example, after obtaining the uncrosslinked rubber composition C or in the middle of the process to obtain the uncrosslinked rubber composition C. The addition of the solvent described above is optional. Next, the obtained coating rubber is applied to one side of the impregnated tooth cloth body so that a rubber reservoir is formed, and the tooth cloth body is passed between a pair of pressure rolls to coat one side of the tooth cloth body with the coating rubber containing the uncrosslinked rubber composition C. After that, a drying process (heating process) is performed as needed to remove the solvent contained in the goating rubber. The conditions for this drying process can be determined appropriately, taking into consideration the composition of the coating rubber mentioned above. Step (C) may be omitted.

[0090] The uncrosslinked tooth cloth 24 prepared in this manner is composed of a woven, knitted, or nonwoven fabric and comprises a tooth cloth body that is RFL-treated as needed, and an uncrosslinked rubber composition B impregnated into the tooth cloth body. Furthermore, the uncrosslinked tooth cloth 24 may be coated as needed. The uncrosslinked tooth cloth 24 only needs to have the impregnated uncrosslinked rubber composition B on one side of the tooth cloth body. Therefore, in the preparation of the uncrosslinked tooth cloth, in step (B), only one side of the tooth cloth body may be brought into contact with the impregnation treatment liquid to allow the impregnation treatment liquid to soak into the tooth cloth body.

[0091] (2) As shown in Figure 4, first, the uncrosslinked tooth cloth 24, which is formed into a cylindrical shape, is placed on the outer surface of the mold 5. Next, the core wires 3 are spirally wound over the uncrosslinked tooth fabric 24. At this time, it is preferable to pair S-twisted core wires and Z-twisted core wires and wind them spirally. After winding the core wire 3, the uncrosslinked rubber sheet 23 is then wound around it. Multiple sheets of the uncrosslinked rubber sheet 23 (two sheets in Figure 4) are wound around it. As a result, an uncrosslinked molded body 13C is formed on the outer circumference of the mold 5, in which the uncrosslinked tooth fabric 24, the core wire 3, and the uncrosslinked rubber sheet 23 are laminated together. When multiple uncrosslinked rubber sheets 23 are wrapped around each other, each uncrosslinked rubber sheet may have the same composition or a different composition.

[0092] (3) As shown in Figure 5, the rubber sleeve 6 is placed over the uncrosslinked molded body 13C on the mold 5. The uncrosslinked molded body 13C with the rubber sleeve 6 is placed inside a vulcanizing can (not shown) together with the mold 5, and the vulcanizing can is sealed. High-temperature and high-pressure steam is filled into the vulcanizing can. This state is maintained for a predetermined time. As a result, the uncrosslinked molded body 13C is pressed towards the mold 5 and heated. The uncrosslinked rubber sheet 23 flows within the cavity formed between the mold 5 and the rubber sleeve 6. The uncrosslinked rubber sheet 23 passes between the core wires 3. The uncrosslinked rubber sheet 23 flows into each of the multiple recesses 51 provided in the mold 5 while pressing against the uncrosslinked tooth fabric 24. As the uncrosslinked rubber sheet 23 flows within the cavity in this manner, it integrates with the core wires 3 and the uncrosslinked tooth fabric 24 and becomes crosslinked. At this time, the uncrosslinked tooth fabric 24 also becomes crosslinked as it flows within the cavity. As a result, a cylindrical belt slab 14B is formed, as shown in Figure 6.

[0093] (4) The inside of the vulcanizing can is depressurized to release the seal. The belt slab 14B formed between the mold 5 and the rubber sleeve 6 is demolded. The back surface of the demolded belt slab 14B is polished to adjust its thickness, and if necessary, markings such as the lot number and product name are applied. After that, the belt slab 14B is cut into slices. The toothed belt 1 is obtained by going through these steps. [Examples]

[0094] The embodiments of the present invention will be described in more detail below with reference to examples, but the embodiments of the present invention are not limited to the following examples. In both the examples and comparative examples, toothed belts were manufactured and their performance was evaluated. Each toothed belt manufactured has a similar configuration except for differences in the arrangement of the tooth fabric.

[0095] (Dimensions of toothed belt) We manufactured a type of toothed belt called S5M. The dimensions of this toothed belt are as follows, indicated by the symbols shown in Figure 7. Pb=5.0mm, Tb=3.61mm, h1=1.70mm, h2=1.91mm, R=3.25mm, W=3.25mm, a=0.381mm, r1=0.50mm, r2=0.50mm, PLD=0.480mm.

[0096] In each example and comparative example, a toothed belt for evaluating the amount of scattered material generated and a toothed belt for evaluating durability were manufactured. The toothed belt used for evaluating the amount of scattered debris has teeth of the dimensions described above, with a belt length of 400 mm and a belt width of 20 mm. The toothed belt used for evaluating durability has teeth of the dimensions described above, with a belt length of 710 mm and a belt width of 10 mm.

[0097] (Belt raw material) (1) Uncrosslinked rubber composition The following uncrosslinked rubber composition was prepared as uncrosslinked rubber composition A for forming the belt body (base and teeth). The base rubber is a mixture of 60 parts by mass of hydrogenated nitrile rubber (H-NBR) (manufactured by Nippon Zeon Co., Ltd., product name: Z-Pole 2010L) and 40 parts by mass of hydrogenated nitrile rubber containing an unsaturated carboxylic acid metal salt (manufactured by Nippon Zeon Co., Ltd., product name: ZSC2195LCX), and per 100 parts by mass of this base rubber, the following ingredients are added: 5 parts by mass of zinc oxide (manufactured by Sakai Chemical Industry Co., Ltd., product name: Zinc Oxide 3), 2 parts by mass of antioxidant (manufactured by Ouchi Shinko Chemical Co., Ltd., product name: Nocrack MB), 0.5 parts by mass of antioxidant (manufactured by Jiangsu Feiya Chemical Industry Co., Ltd., product name: KY-405), 0.3 parts by mass of sulfur (manufactured by Hosokawa Chemical Industry Co., Ltd., product name: HK200-5), 20 parts by mass of carbon black FEF (manufactured by Tokai Carbon Co., Ltd., product name: Seast SO), and silica (Evonik Industries). An uncrosslinked rubber composition A was prepared by kneading together 20 parts by mass of AG (product name: Ultrazil VN-3), 5 parts by mass of plasticizer ((Adeka Corporation, product name: Adekaiser RS-700)), 3 parts by mass of co-crosslinking agent (Ouchi Shinko Chemical Industry Co., Ltd., product name: Valnock PM), 2 parts by mass of co-crosslinking agent (Shinryo Co., Ltd., product name: Taik)), 0.5 parts by mass of stearic acid (Shin Nippon Rika Co., Ltd., product name: Stearic Acid), 3 parts by mass of short fibers (Teijin Limited, product name: CFH1050), and 8 parts by mass of crosslinking agent (NOF Co., Ltd., product name: Peroximon F40).

[0098] (2) Core wire A carbon core wire with the following configuration was prepared. Carbon fiber (Toray Industries, Ltd., product name: Torayca T800HB-6000, filament diameter 5.0 μm, number of filaments 6000) was used, and a single-twist yarn was twisted 6 times per 10 cm to form the carbon core wire. The core wire diameter is 0.55 mm. Two types of core wires were prepared: S-twist yarn and Z-twist yarn.

[0099] (3) Uncrosslinked tooth cloth As the fibrous material constituting the tooth cloth body, a 2 / 2 twill weave fabric (nylon canvas) was prepared using 6,6-nylon woolly processed yarn (breaking elongation of 150% or more) with warp threads of 235 dtex and weft threads of 155 dtex. Part or all of the following treatments were performed under predetermined conditions: (A) RFL treatment, (B) impregnation treatment, and (C) coating treatment. Details of each treatment will be described later.

[0100] [Example 1] (1) The above nylon canvas was subjected to RFL treatment (A1), impregnation treatment (B1), and coating treatment (C1) in this order to prepare an uncrosslinked toothed fabric.

[0101] The RFL processing (A1) is as follows: An initial condensate solution was obtained by adding resorcinol and formalin to a sodium hydroxide solution in a molar ratio R / F = 1 / 2 and stirring. Latex and water were added to the obtained solution and stirred to prepare an RFL solution with a mass ratio of resorcinol / formalin to latex RF / L = 1 / 8.

[0102] Next, carbon black was added to the RFL solution and stirred and mixed. Then, sodium dioctyl sulfosuccinate (anionic surfactant) was added and stirred and mixed to prepare the adhesive treatment solution. Here, the amount of carbon black added was 58.6 parts by mass relative to 213.4 parts by mass of solids in the RFL solution, and the amount of sodium dioctyl sulfosuccinate added was 14.0 parts by mass relative to 213.4 parts by mass of solids in the RFL solution.

[0103] After immersing the nylon canvas in the adhesive treatment solution, it was lifted out and passed between a pair of pressure rolls to allow the adhesive treatment solution to adhere to the nylon canvas. Subsequently, a pre-drying treatment was performed at 120°C, followed by a baking treatment at 150°C or 160°C. This treatment was performed twice, with the first baking temperature at 150°C and the second baking temperature at 160°C. This resulted in RFL-treated nylon canvas.

[0104] The impregnation treatment (B1) is as follows: 100 parts by mass of an H-NBR composite (manufactured by Nippon Zeon Co., Ltd., ZSC2195H (H-NBR content: 50% by mass)) containing H-NBR and zinc methacrylate was mixed with 140 parts by mass of polytetrafluoroethylene (manufactured by Asahi Glass Co., Ltd., trade name: Fluon L173JE, average particle size: 10 μm or less), 5 parts by mass of zinc oxide (manufactured by Sakai Chemical Industry Co., Ltd., trade name: Zinc Oxide 3), 2 parts by mass of antioxidant (manufactured by Ouchi Shinko Chemical Co., Ltd., trade name: Nocrack MB), 0.5 parts by mass of antioxidant (manufactured by Jiangsu Feiya Chemical Industry Co., Ltd., trade name: KY-405), 1 part by mass of carbon black HAF (manufactured by Tokai Carbon Co., Ltd.), 20 parts by mass of silica (manufactured by Evonik Industries AG, trade name: Ultrazil VN-3), and 5 parts by mass of plasticizer (Adeka Co., Ltd., trade name: Adekaiser RS-700), and kneaded to obtain an uncrosslinked rubber composition B'.

[0105] 206.66 parts by mass of solvent (MEK: methyl ethyl ketone) was used to dissolve 100 parts by mass of uncrosslinked rubber composition B'. Then, 2.25 parts by mass of cocrosslinking agent (Ouchi Shinko Chemical Industry Co., Ltd., trade name: Valnock PM) and 1.08 parts by mass of crosslinking agent (NOF Corporation, trade name: Perbutyl P) were mixed in. Subsequently, 309.99 parts by mass of MEK (methyl ethyl ketone) was added to the resulting mixture, and the mixture was diluted twice to prepare an impregnation treatment solution containing uncrosslinked rubber composition B.

[0106] The RFL-treated nylon canvas was immersed in this impregnation solution. Afterward, it was removed and passed between a pair of pressure rollers with adjusted nip pressure to remove excess impregnation solution. The impregnation solution temperature was 23°C, the immersion time was 3 seconds, and the treatment was repeated once. Here, the nip pressure is adjusted so that the occupancy rate of the toothed belt is 15%.

[0107] Subsequently, the nylon canvas coated with the impregnation solution was dried. The drying process was carried out in a drying oven with an ambient temperature of 120°C, by wrapping the nylon canvas coated with the adhesive solution around a drum adjusted to 130°C and feeding it at a feed rate of 4 m / min.

[0108] The coating process (C1) is as follows: 100 parts by mass of blended rubber made by kneading 80% by mass of H-NBR composite (ZSC2195H, manufactured by Nippon Zeon Co., Ltd.) containing H-NBR and zinc methacrylate, and 20% by mass of H-NBR (ZP2000, manufactured by Nippon Zeon Co., Ltd.), 10 parts by mass of zinc oxide (manufactured by Sakai Chemical Industry Co., Ltd., product name: Zinc Oxide 3), 1 part by mass of antioxidant (manufactured by Ouchi Shinko Chemical Co., Ltd., product name: Nocrack MB), 1 part by mass of antioxidant (manufactured by Jiangsu Feiya Chemical Industry Co., Ltd., product name: KY-405), 0.5 parts by mass of antioxidant (manufactured by Ouchi Shinko Chemical Co., Ltd., product name: Nocrack 224), 20 parts by mass of carbon black GPF (manufactured by Tokai Carbon Co., Ltd.), and silica (Evonik Industries Uncrosslinked rubber composition C' was prepared by mixing and kneading 10 parts by mass of AG (product name: Ultrazil VN-3), 8 parts by mass of a plasticizer (Adeka Corporation, product name: Adekaiser RS-700), 3 parts by mass of a cocrosslinking agent (Highcross M, manufactured by Seiko Chemical Co., Ltd.), and 0.5 parts by mass of sulfur (Hosokawa Chemical Industry Co., Ltd., product name: HK200-5).

[0109] 100 parts by mass of the obtained uncrosslinked rubber composition C' was dissolved in 210.66 parts by mass of solvent (MEK: methyl ethyl ketone), and then 3.25 parts by mass of cocrosslinking agent (Ouchi Shinko Chemical Industry Co., Ltd., trade name: Valnock PM) and 2.08 parts by mass of crosslinking agent (NOF Corporation, trade name: Perbutyl P) were mixed to prepare a coating rubber containing uncrosslinked rubber composition C.

[0110] This coating rubber was applied to one side of the impregnated nylon canvas (the side that would become the belt body) and allowed to dry. This drying process was carried out in a drying oven with an ambient temperature of 120°C, by wrapping nylon canvas coated with rubber around a drum adjusted to 130°C and feeding it at a feed rate of 10 m / min.

[0111] (2) Using the uncrosslinked rubber composition and core wire described above, and using the uncrosslinked tooth fabric prepared in (1) above, toothed belts were manufactured according to the manufacturing method described above (see Figures 4 to 6). Here, two types of toothed belts with different dimensions, as already described, were manufactured. In this configuration, the core wires were arranged in a double helix pattern, with S-twisted and Z-twisted threads alternating in the belt width direction, and the pitch between adjacent core wires being 0.75 mm. The proportion of toothed fabric-impregnated rubber in the resulting toothed belt was 15%.

[0112] [Example 2] A toothed belt was manufactured in the same manner as in Example 1, except that impregnation treatment (B2) was performed instead of impregnation treatment (B1) in the preparation of the uncrosslinked toothed fabric. Impregnation treatment (B2) is carried out in the same manner as impregnation treatment (B1), except that the amount of polytetrafluoroethylene contained in the uncrosslinked rubber composition B' is changed from 140 parts by mass to 170 parts by mass. The proportion of toothed fabric-impregnated rubber in the resulting toothed belt was 14%.

[0113] [Example 3] A toothed belt was manufactured in the same manner as in Example 1, except that impregnation treatment (B3) was performed instead of impregnation treatment (B1) in the preparation of the uncrosslinked toothed fabric. Impregnation treatment (B3) is carried out in the same manner as impregnation treatment (B1), except that the amount of polytetrafluoroethylene contained in the uncrosslinked rubber composition B' is changed from 140 parts by mass to 200 parts by mass. The proportion of toothed fabric-impregnated rubber in the resulting toothed belt was 15%.

[0114] [Example 4] In the impregnation process (B3), a toothed belt was manufactured in the same manner as in Example 3, except that the nip pressure was increased to increase the amount of impregnation liquid removed in the operation of lifting the nylon canvas immersed in the impregnation liquid and passing it between a pair of pressure rolls to remove excess impregnation liquid. In this embodiment 4, a toothed belt was manufactured with a lower proportion of toothed fabric-impregnated rubber compared to embodiment 3. The proportion of toothed fabric-impregnated rubber in the resulting toothed belt was 4%.

[0115] [Example 5] In the impregnation process (B3), a toothed belt was manufactured in the same manner as in Example 3, except that the nip pressure was reduced to decrease the amount of impregnation liquid removed in the operation of lifting the nylon canvas immersed in the impregnation liquid and passing it between a pair of pressure rolls to remove excess impregnation liquid. In this Example 5, a toothed belt was manufactured with a higher proportion of toothed fabric-impregnated rubber compared to Example 3. The proportion of toothed fabric-impregnated rubber in the resulting toothed belt was 16%.

[0116] [Comparative Example 1] In the preparation of the uncrosslinked toothed fabric, RFL treatment (A2) was performed instead of RFL treatment (A1), and impregnation treatment (B1) was omitted, but otherwise a toothed belt was manufactured in the same manner as in Example 1. RFL treatment (A2) is carried out in the same manner as RFL treatment (A1), except that 100 parts by mass of polytetrafluoroethylene (manufactured by Asahi Glass Co., Ltd., trade name: Fluon L173JE, average particle size: 10 μm or less) is added to the RFL solution when preparing the adhesive treatment solution.

[0117] [Comparative Example 2] A toothed belt was manufactured in the same manner as in Example 1, except that impregnation treatment (B1) was not performed in the preparation of the uncrosslinked tooth fabric. In this comparative example, RFL treatment (A1) was performed, followed by coating treatment (C1).

[0118] [Comparative Example 3] A toothed belt was manufactured in the same manner as in Example 1, except that impregnation treatment (B4) was performed instead of impregnation treatment (B1) in the preparation of the uncrosslinked toothed fabric. Impregnation treatment (B4) is carried out in the same manner as impregnation treatment (B1), except that polytetrafluoroethylene is not included in the uncrosslinked rubber composition B'. The proportion of toothed fabric-impregnated rubber in the resulting toothed belt was 14%.

[0119] [Comparative Example 4] A toothed belt was manufactured in the same manner as in Example 1, except that impregnation treatment (B5) was performed instead of impregnation treatment (B1) in the preparation of the uncrosslinked toothed fabric. Impregnation treatment (B5) is carried out in the same manner as impregnation treatment (B1), except that the amount of polytetrafluoroethylene contained in the uncrosslinked rubber composition B' is changed from 140 parts by mass to 210 parts by mass. The proportion of toothed fabric-impregnated rubber in the resulting toothed belt was 14%.

[0120] [Comparative Example 5] A toothed belt was manufactured in the same manner as in Example 1, except that impregnation treatment (B6) was performed instead of impregnation treatment (B1) in the preparation of the uncrosslinked toothed fabric. Impregnation treatment (B6) is carried out in the same manner as impregnation treatment (B1), except that the amount of polytetrafluoroethylene contained in the uncrosslinked rubber composition B' is changed from 140 parts by mass to 300 parts by mass. The proportion of toothed fabric-impregnated rubber in the resulting toothed belt was 14%.

[0121] [Comparative Example 6] A toothed belt was manufactured in the same manner as in Example 1, except that impregnation treatment (B7) was performed instead of impregnation treatment (B1) in the preparation of the uncrosslinked toothed fabric. Impregnation treatment (B7) is carried out in the same manner as impregnation treatment (B1), except that the amount of polytetrafluoroethylene contained in the uncrosslinked rubber composition B' is changed from 140 parts by mass to 380 parts by mass. The proportion of toothed fabric-impregnated rubber in the resulting toothed belt was 15%.

[0122] [Comparative Example 7] A toothed belt was manufactured in the same manner as in Example 1, except that impregnation treatment (B8) was performed instead of impregnation treatment (B1) in the preparation of the uncrosslinked toothed fabric. Impregnation treatment (B8) is carried out in the same manner as impregnation treatment (B1), except that the amount of polytetrafluoroethylene contained in the uncrosslinked rubber composition B' is changed from 140 parts by mass to 120 parts by mass. The proportion of toothed fabric-impregnated rubber in the resulting toothed belt was 14%.

[0123] (evaluation) Belt running test A and belt running test B were performed on the toothed belts manufactured in the examples and comparative examples. The results are shown in Table 1.

[0124] (1) Belt running test A (Scattered debris occupancy rate test) This test evaluates the amount of debris generated from a toothed belt during belt operation. Figure 8 shows the layout of the test machine 100 used in belt running test A. The testing machine 100 comprises a drive pulley 102 and a driven pulley 103 located above it. The testing machine 100 further comprises a dust collection sheet 104 placed on a flat surface. The distance H from the surface of the dust collection sheet 104 to the drive pulley 102 is 190 mm. Belt running test A is performed by wrapping the toothed belt 101 (20 mm wide, 400 mm long) to be evaluated around the belt.

[0125] The drive pulley 102 has 20 teeth and a pitch diameter of 31.83 mm. The driven pulley 103 has 50 teeth and a pitch diameter of 79.58 mm.

[0126] Belt running test A is conducted under the following conditions: drive side rotation speed 3000 rpm, driven side rotation speed 1200 rpm, driven side maximum load 9 N·m, span tension 170 N, ambient temperature 23 ± 5 °C, and running test for 24 hours. In this running test, a belt running test was conducted for 24 hours, in which the belt repeatedly rotated forward and in reverse in a predetermined cycle pattern, and the amount of debris generated during the running test was evaluated.

[0127] Figure 9 is a graph showing the cycle pattern. In this belt running test A, the cycle pattern shown in Figure 9 is repeated. This cycle pattern, as shown in Figure 9, consists of a combination of an acceleration time of 0.282 seconds, a constant speed rotation time of 0.518 seconds, and a deceleration time of 0.282 seconds. The time from the completion of deceleration to the start of acceleration is 1 second.

[0128] This image is a binarized version of the image taken before the belt was driven. The amount of scattered debris is evaluated using the following procedure. (a) Take an image of the dust collection sheet 104 before the belt runs. (b) Run the belt for 24 hours under the conditions already described. (c) Take an image of the dust collection sheet 104 after the belt has been driven.

[0129] (d) Crop each of the images taken in (a) and (c) to 5cm x 5cm. The images obtained in (e) and (d) are binarized. At this time, the binarization process is performed with a brightness of 165 as the threshold. Based on the binarized images obtained in (f) and (e), the area of ​​the increased black portion due to the driving test was determined, and the percentage of this area relative to the total area of ​​the cropped image (5cm × 5cm) was calculated to determine the percentage of scattered debris. The results are shown in Table 1.

[0130] Figure 10 shows an example of a binarized image before and after a belt running test. In Figure 10, the image on the left is the binarized image of the image before belt running, and the image on the right is the binarized image of the image before belt running. As can be seen from Figure 10, the belt running test A allows us to evaluate the amount of debris scattered by the movement of the belt.

[0131] In this belt running test A, the imaging equipment used is the "Simple Foreign Object Inspection Tool BANDO DEC-20 (registered trademark)" manufactured by Bando Chemical Co., Ltd. The image acquisition software used is the free software "GaZoo Capture" from GaZoo Co., Ltd. The image processing software used is the public domain software "Imagej" (open source).

[0132] (2) Belt running test B (tooth chipping durability test) This test evaluates the tooth breakage resistance of a toothed belt. Figure 11 shows the pulley layout of the belt running test machine 200 used in belt running test B. The belt running test machine 200 comprises a drive pulley 202, a driven pulley 203 located to its right, and a rear idler pulley 204. The driven pulley 203 is movably mounted to the left and right so that a set weight (SW) can be loaded onto it. Belt running test B is performed by wrapping the toothed belt 201 (10 mm wide, 710 mm long) to be evaluated around the belt.

[0133] The drive pulley 202 has 26 teeth and a pitch diameter of 41.38 mm. The driven pulley 203 has 52 teeth and a pitch diameter of 82.76 mm. The rear idler pulley 204 has an outer diameter of 40 mm.

[0134] Belt running test B is conducted under the following conditions: drive side rotation speed of 7000 rpm, driven side rotation speed of 3500 rpm, driven side load of 23.5 N·m, set weight of 785 N, and ambient temperature of 60°C. In this running test, the time until tooth breakage occurred was measured. In this evaluation, the test was terminated in both the example and comparative example when tooth breakage occurred in the belt teeth. The results are shown in Table 1. The results shown in Table 1 are relative values ​​with the running time of Example 1 set to 100.

[0135] [Table 1]

[0136] As shown in Table 1, the toothed belt according to the embodiment of the present invention ensures sufficient durability while reducing the amount of flying debris during belt operation. [Industrial applicability]

[0137] The toothed belt technology, which reduces the amount of debris scattered from the belt while ensuring the durability described above, is suitable as a power transmission means used in fields where a clean environment is required, such as industrial robots. [Explanation of Symbols]

[0138] 1, 101, 201 Toothed belt 2. Belt body 3 core wires 4 Tooth cloth 5. Mold 6 Rubber sleeve 11 Back 12 belt teeth 13C Uncrosslinked molded body 14B Belt Slab 21 Base 22 Teeth 23 Uncrosslinked rubber sheet 24 Uncrosslinked tooth cloth 41 Tooth cloth body 42 Toothcloth-impregnated rubber (crosslinked rubber composition) 43 Coating layer 51 Recess 52 Convex part 100, 200 belt running test machine 102, 202 drive pulley 103, 203 Driven pulley 104 Dust Collection Sheet 204 Rear Idler Pulley

Claims

1. A belt body having multiple teeth arranged at a constant pitch on the inner circumference of the belt, The core wire embedded in the belt body, A tooth cloth covering the plurality of teeth is provided on the inner circumference side of the belt body, Equipped with, The tooth cloth comprises a tooth cloth body made of woven, knitted, or nonwoven fabric, and a crosslinked material of an uncrosslinked rubber composition impregnated into the inner circumference of the belt of the tooth cloth body. The aforementioned uncrosslinked rubber composition comprises an uncrosslinked rubber component and a friction coefficient reducing agent, wherein the content of the friction coefficient reducing agent is 130 parts by mass or more and 200 parts by mass or less per 100 parts by mass of the rubber component. The rubber component is at least one selected from hydrogenated nitrile rubber (H-NBR), ethylene propylene diene rubber (EPDM), and chloroprene rubber (CR), in a toothed belt.

2. The toothed belt according to claim 1, wherein the friction-reducing agent is PTFE particles with an average particle size of 10 μm or less.

3. The toothed belt according to claim 1 or 2, wherein the uncrosslinked rubber composition comprises H-NBR as the rubber component and further comprises an unsaturated carboxylic acid metal salt.

4. A toothed belt according to claim 1 or 2, wherein the tooth pitch is 3 mm or more and 5 mm or less.

5. The inner circumferential surface is made of the tooth cloth, The tooth cloth body and the crosslinked material of the uncrosslinked rubber composition are exposed on the inner circumferential surface. The toothed belt according to claim 1 or 2.

6. A method for manufacturing a toothed belt using a pre-prepared uncrosslinked rubber composition for making the belt body, a core wire, and an uncrosslinked tooth fabric, The process of preparing the uncrosslinked tooth cloth is as follows: (a) A step of immersing a tooth cloth body, which is made of woven, knitted or nonwoven fabric, in a treatment solution containing an uncrosslinked rubber component, a friction coefficient reducing agent and a solvent, and (b) After removing the tooth cloth body from the processing liquid, the heating step includes removing the solvent, A method for manufacturing a toothed belt, wherein the rubber component is at least one selected from hydrogenated nitrile rubber (H-NBR), ethylene propylene diene rubber (EPDM), and chloroprene rubber (CR).

7. The method for manufacturing a toothed belt according to claim 6, wherein the amount of the friction coefficient reducing agent in the processing liquid is 130 parts by mass or more and 200 parts by mass or less per 100 parts by mass of the rubber component.

8. The method for manufacturing a toothed belt according to claim 6 or 7, wherein the processing liquid contains H-NBR as the rubber component and further contains an unsaturated carboxylic acid metal salt.

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