JP2016183779A - Toothed belt - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a toothed belt of high oil resistance and high abrasion resistance of a coat layer on a tooth cloth surface.SOLUTION: In a toothed belt including a tooth portion 2 engageable with a toothed pulley, a tooth cloth 4 covering the tooth portion, and a coat layer covering the tooth cloth, the coat layer is composed of a rubber composition including a rubber component including hydrogenated nitrile rubber containing 32-40 mass% of bonded acrylonitrile, and short fiber 5 having an average fibber length of 0.5 mm or more. At least a part of the hydrogenated nitrile rubber may form a composite by being combined with unsaturated carboxylic acid metal salt. An average fiber length of the short fiber may be about 0.5-5 mm. The short fiber may be polyamide fiber. A ratio of the short fiber may be 1-30 pts.mass to 100 pts.mass of the rubber component.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a toothed belt for transmitting rotation of a crankshaft to an open / close drive camshaft or the like of an intake / exhaust valve in an internal combustion engine or driving an oil pump adjacent to the internal combustion engine.

  Usually, the transmission belt is provided outside the engine, but in recent years, the transmission belt may be used inside the engine in order to reduce the weight of the internal combustion engine. The power transmission belt used inside the internal combustion engine is used in an environment that is always in contact with the lubricating oil inside the engine. As such a transmission belt, a toothed portion made of rubber formed by providing tooth portions at predetermined intervals along the longitudinal direction of the belt on the back portion of the belt in which the core wire is embedded and covering the surface of the tooth portion with a tooth cloth. It is common to use a belt.

  FIG. 1 is a schematic sectional perspective view showing an example of a conventional toothed belt, and FIG. 2 is a schematic sectional perspective view enlarging a part of FIG. 1, but the toothed belt is arranged in the longitudinal direction of the belt. A plurality of tooth portions 2 formed at predetermined intervals along the belt and a back portion 1 having a plurality of core wires 3 embedded along the longitudinal direction of the belt. 4 is stuck (coated or laminated). In addition, the tooth | gear part 2 is formed in the trapezoid shape in the longitudinal cross-section. Further, short fibers 5 arranged along the substantially longitudinal direction of the belt are also embedded in the back portion 1 and the tooth portion 2. Further, the tooth cloth 4 is composed of a plurality of wefts 7 extending in the longitudinal direction of the belt and warps 6 extending in the lateral direction of the belt.

  When this rubber toothed belt is used in an environment in contact with the lubricating oil, the rubber toothed belt is required to have extreme oil resistance. Then, prescription is examined about the rubber layer which comprises a toothed belt main body in order to ensure oil resistance and a reinforcement effect.

  On the other hand, the reinforcing cloth (tooth cloth) covering the tooth surface needs to have extreme oil resistance and wear resistance so that it can withstand even in an environment where it always contacts the lubricating oil. Specifically, as the tooth cloth, fiber fabrics (plain fabric, twill fabric, satin fabric, etc.) produced by weaving warp yarns arranged in the belt width direction and weft yarns arranged in the belt longitudinal direction are used as the base material. It is done. Furthermore, in order for this tooth cloth to adhere to the rubber layer which comprises a tooth | gear part, the adhesion treatment agent is coated on the surface of a fiber fabric. As the adhesion treatment, first, the fiber woven fabric is first impregnated with an RFL treatment solution and dried, and then an adhesion treatment agent made of a rubber paste obtained by dissolving the rubber composition in a solvent is attached to perform a baking treatment. In this case, the rubber composition is coated (attached) to the surface of the tooth cloth. Therefore, with regard to the rubber composition coated on the surface of the tooth cloth, the coated rubber is peeled off during traveling in oil unless it has extreme oil resistance and wear resistance so that it can withstand the environment that is always in contact with the lubricating oil. Tooth wear will progress.

  Various types of toothed belts that improve the life of such toothed belts have been proposed. For example, Japanese Patent Publication No. 2009-523979 (Patent Document 1) discloses a rubber that forms a belt back portion and a tooth portion, in particular, A method is disclosed in which hydrogenated nitrile rubber (HNBR) is used as the rubber (elastomer material) forming the tooth portion, and the core wire and the tooth cloth are treated with a fabric treatment agent for further extending the life. In this document, as a fabric treating agent, HNBR containing 30 to 39% by mass (particularly 34 to 36% by mass) of a nitrile group-containing monomer (bound acrylonitrile amount or bound AN amount in HNBR) is included. It is described that after being immersed in one fabric treatment agent, a second fabric treatment agent having a composition similar to that of the first fabric treatment agent is applied. Further, a resistance layer is further laminated on the treated fabric via an adhesive, and this resistance layer contains a fluorinated plastomer (particularly polytetrafluoroethylene) and HNBR in a rich ratio of the fluorinated plastomer.

  In Japanese Translation of PCT International Publication No. 2012-522953 (Patent Document 2), fibers (short fibers) contained in a rubber composition (first elastomer material) forming a belt back portion and a tooth portion are used as a core wire (durable insert). A toothed belt is disclosed that is arranged to extend in a direction substantially perpendicular to the axis and substantially parallel to a plane defined by the axis of the core wire. In this document, nitrile rubber (NBR) and hydrogenated nitrile rubber (HNBR) having excellent oil resistance are exemplified as the elastomer material, and the ratio of the nitrile group-containing monomer (bound acrylonitrile amount or bound AN amount) is 34 to 53. It is described that it is mass% and 49 to 51 mass% is preferable. Furthermore, it is also described that a cover layer (durable layer) is formed by appropriately selecting the amount of the treating agent for the covering cloth, which is a tooth cloth. As this treating agent, a fluorinated plastomer (for example, polytetrafluoroethylene) is described. ) And a treatment agent containing HNBR having a bonded AN amount of 34 to 60% by mass (preferably 49 to 51% by mass). Even in this durable layer, the proportion of fluorinated plastomer is richer than HNBR.

  In JP2012-197857A (Patent Document 3), a rubber layer forming a tooth portion is formed of a rubber composition containing a rubber component containing HNBR having an iodine value of 11 mg / 100 mg or less and short fibers. In addition, a toothed belt is disclosed in which the short fibers are surface-treated with an adhesive treatment containing a copolymer containing a nitrile group. In this document, the use of HNBR having high oil resistance as an adhesive treatment agent for the short fibers suppresses the swelling of the rubber (ensures oil resistance), while the reinforcing effect by the short fibers (rubber and short fibers and It is described that the adhesiveness of the resin can be improved. Furthermore, it is described that an adhesive treatment agent made of a rubber composition (rubber paste) containing HNBR as a rubber component is coated on the surface of a fiber fabric forming a tooth cloth.

  However, even with these toothed belts, the oil resistance and wear resistance are not sufficient, and in particular, since the adhesive force between the tooth cloth and the coat layer is small, the coat layer of the tooth cloth peels off during running in oil, and the tooth Cloth wear progresses.

JP-T-2009-523979 (Claim 1, paragraphs [0045] to [0055]) JP-T-2012-522953 (Claim 1, paragraphs [0055] to [0060]) JP 2012-197857 A (Claim 1, paragraphs [0007] to [0010] [0042])

  An object of the present invention is to provide a toothed belt having high oil resistance and wear resistance of a coat layer on the surface of a tooth cloth.

  Another object of the present invention is to provide a toothed belt capable of suppressing the wear of tooth cloth in an environment in contact with the lubricating oil and extending the belt running life without using a release agent such as a fluororesin. It is in.

  As a result of earnest studies to achieve the above-mentioned problems, the present inventors combined a rubber component containing a hydrogenated nitrile rubber having a bound acrylonitrile amount of 32 to 40% by mass and a short fiber having an average fiber length of 0.5 mm or more, It has been found that by covering the tooth cloth of the toothed belt, the oil resistance and wear resistance of the coat layer on the tooth cloth surface can be improved, and the present invention has been completed.

  That is, the toothed belt of the present invention is a toothed belt including a tooth part meshable with a toothed pulley, a tooth cloth covering the tooth part, and a coat layer covering the tooth cloth, The coat layer is formed of a rubber composition containing a rubber component (A) containing a hydrogenated nitrile rubber (a) having a bound acrylonitrile amount of 32 to 40% by mass and a short fiber (B) having an average fiber length of 0.5 mm or more. ing. At least a part of the hydrogenated nitrile rubber (a) may be complexed with an unsaturated carboxylic acid metal salt to form a complex (a1). In the hydrogenated nitrile rubber (a), the mass ratio between the complex (a1) and the non-complex (a2) not complexed with the unsaturated carboxylic acid metal salt is complex (a1) / non-complex. (A2) = 10/90 to 99/1 (especially 60/40 to 80/20). The hydrogenated nitrile rubber (a) may have an iodine value of about 8 to 13 mg / 100 mg. About 0.5-5 mm may be sufficient as the average fiber length of the said short fiber (B). The short fibers (B) may be polyamide fibers (especially aromatic polyamide fibers). The proportion of the short fibers (B) may be about 1 to 30 parts by mass (particularly 2 to 10 parts by mass) with respect to 100 parts by mass of the rubber component (A). The rubber composition may not contain a fluororesin. The coat layer may have an average thickness of 10 μm or more.

  In the present specification and claims, “bound acrylonitrile amount (bound AN amount)” means the central value of the mass ratio (acrylonitrile content) of acrylonitrile units in hydrogenated nitrile rubber (HNBR).

  In the present invention, the tooth fabric of the toothed belt is coated with a rubber composition containing a hydrogenated nitrile rubber having a bonded AN amount of 32 to 40% by mass and short fibers having an average fiber length of 0.5 mm or more. Therefore, the oil resistance and wear resistance of the coat layer on the tooth cloth surface can be improved. Furthermore, without using a release agent such as a fluororesin, it is possible to suppress wear of the tooth cloth in an environment in contact with the lubricating oil, and to extend the belt running life.

FIG. 1 is a schematic sectional perspective view showing an example of a conventional toothed belt. FIG. 2 is a schematic cross-sectional perspective view in which a part of FIG. 1 is enlarged. FIG. 3 is a schematic view of a triaxial lubrication running test machine in the embodiment.

[Coat layer]
The toothed belt of the present invention comprises a rubber component (A) containing hydrogenated nitrile rubber (a) having a surface of the tooth cloth (transmission surface) of 32 to 40% by mass of bonded AN (acrylonitrile content) and an average fiber length of 0. It is coat | covered with the coating layer formed with the rubber composition containing 5 mm or more of short fibers (B).

(A) Rubber component The rubber component (A) contains hydrogenated nitrile rubber (HNBR) (a) having a bound AN amount (center value) of 32 to 40% by mass. Rubber has high oil resistance. Therefore, generation | occurrence | production of swelling can be suppressed more, the abrasion resistance by a short fiber can be improved, and peeling of a coating layer can be suppressed even in driving | running | working in oil. The amount of bonded AN in the hydrogenated nitrile rubber (a) is preferably about 33 to 39% by mass, more preferably about 34 to 38% by mass (particularly about 35 to 37% by mass). If the amount of bonded AN is too small, the heat resistance, oil resistance, and wear resistance are lowered, and if the amount of bonded AN is too large, crosslinking becomes difficult and the durability of the belt decreases.

  In the present specification and claims, a method such as a semi-micro Kjeldahl method according to JIS K6384 can be used as a method for measuring the amount of bound AN.

  The iodine value (central value) of the hydrogenated nitrile rubber (a) is, for example, about 5 to 20 mg / 100 mg, preferably 7 to 15 mg / 100 mg, more preferably 8 to 13 mg / 100 mg (particularly 10 to 12 mg / 100 mg). . If the iodine value of the hydrogenated nitrile rubber (a) is too small, the cross-linking reaction between the hydrogenated nitrile rubbers (a) is not sufficient, and the rigidity of the coat layer becomes low, so that dishing may easily occur during belt running. . On the other hand, if the iodine value of the hydrogenated nitrile rubber (a) is too large, the amount of unsaturated bonds increases excessively, and the heat resistance of the coat layer may deteriorate and deterioration due to oxidation may progress, thereby shortening the belt life. is there.

  In the present specification and claims, the iodine value is measured by adding excess iodine to the sample to be reacted completely (reaction between iodine and unsaturated bonds), and the amount of remaining iodine is determined. It can be determined by quantitative determination by oxidation-reduction titration.

  At least a part of the hydrogenated nitrile rubber (a) may be complexed with an unsaturated carboxylic acid metal salt to form a complex (a1). By combining the hydrogenated nitrile rubber (a) and the unsaturated carboxylic acid metal salt, the strength of the coating layer can be improved, and the swelling resistance by the lubricating oil can also be improved.

  The unsaturated carboxylic acid metal salt is not particularly limited as long as it is a compound in which an unsaturated carboxylic acid having one or more carboxyl groups and a metal are ionically bonded. Examples of the unsaturated carboxylic acid include unsaturated monocarboxylic acids such as (meth) acrylic acid and crotonic acid, and unsaturated dicarboxylic acids such as maleic acid, fumaric acid, itaconic acid, and citraconic acid. These unsaturated carboxylic acids can be used alone or in combination of two or more. Of these unsaturated carboxylic acids, unsaturated monocarboxylic acids such as (meth) acrylic acid are preferred.

  Examples of metals include Group 2 metals (magnesium, calcium, etc.), Group 4 metals (titanium, zirconium, etc.), Group 8 metals (iron, etc.), Group 10 metals (nickel, etc.), and Group 11 metals. Examples include multivalent metals such as (such as copper), Group 12 metal (such as zinc), Group 13 metal (such as aluminum), and Group 14 metal (such as lead). These metals can be used alone or in combination of two or more. Of these metals, divalent metals such as magnesium, calcium and zinc, and trivalent metals such as aluminum (especially divalent metals such as zinc) are preferable.

  Among these, monocarboxylic acid divalent metal salts having a bifunctional radically polymerizable group, for example, zinc di (meth) acrylate such as zinc dimethacrylate, magnesium di (meth) acrylate such as magnesium dimethacrylate (Especially zinc dimethacrylate) is preferred.

  In the composite (a1), the mass ratio of the hydrogenated nitrile rubber and the unsaturated carboxylic acid metal salt can be selected from the range of the former / the latter = about 10/90 to 90/10, for example, 20/80 to 80/20. The ratio is preferably 30/70 to 70/30, more preferably about 40/60 to 60/40. If the ratio of the unsaturated carboxylic acid metal salt is too small, the effect of improving the strength of the coat layer may be reduced, and if too high, the flexibility of the belt may be reduced.

  The form of the composite (a1) is not particularly limited. For example, the composite (a1) may be a form in which an unsaturated carboxylic acid metal salt is finely dispersed in the hydrogenated nitrile rubber (a), and may be a commercially available rubber. A composition or the like can be used.

  The mass ratio between such a complex (a1) and the non-complex (a2) not complexed with the unsaturated carboxylic acid metal salt is complex (a1) / non-complex (a2) = 1 / 99- It can be selected from the range of 100/0, for example 10/90 to 99/1, preferably 20/80 to 95/5 (for example 40/60 to 90/10), more preferably 50/50 to 85/15 (especially 60/40 to 80/20). If the proportion of the composite (a1) is too small, the durability of the belt may be reduced.

  The hydrogenated nitrile rubber (a) is not only a polymerization component acrylonitrile and butadiene, but also a conventional copolymer component (for example, vinyl-based compounds such as methacrylonitrile, (meth) acrylic acid, 2-methyl-5-vinylpyridine). A diene compound such as a compound, isoprene, methylbutadiene, and pentadiene). The proportion of the conventional copolymer component may be 30% by mass or less (particularly 10% by mass or less) based on the entire hydrogenated nitrile rubber (a).

  The rubber component (A) includes hydrogenated nitrile rubber having a bonded AN amount of less than 32% by mass, hydrogenated nitrile rubber having a bonded AN amount exceeding 40% by mass, and other diene rubbers (for example, nitrile rubber, natural rubber). , Chloroprene rubber, etc.), olefin rubber, acrylic rubber, fluorine rubber, silicone rubber, urethane rubber, epichlorohydrin rubber, chlorosulfonated polyethylene rubber, olefin-vinyl ester copolymer, etc. Good.

  The ratio of the hydrogenated nitrile rubber (a) to the rubber component (A) is, for example, 50% by mass or more (50 to 100% by mass), preferably 80% by mass or more, and more preferably 90% by mass or more. (Especially 95% by mass or more). If the proportion of the hydrogenated nitrile rubber (a) is too small, the durability of the belt may be reduced.

(B) Short fiber The short fiber (B) has an average fiber length of 0.5 mm or more, and the durability (abrasion resistance) of the belt can be improved by using the short fiber having such a fiber length. The average fiber length is, for example, 0.5 to 10 mm (for example, 0.5 to 5 mm), preferably 0.5 to 3 mm (for example, 0.6 to 2.5 mm), and more preferably 0.7 to 2 mm (especially 0.2 mm). 8 to 1.5 mm). In particular, when the short fiber is an aromatic polyamide fiber, the average fiber length is, for example, 0.5 to 5 mm, preferably 0.5 to 3 mm (for example, 0.6 to 2 mm), and more preferably 0.7 to 1.mm. It may be about 5 mm (particularly 0.8 to 1.2 mm), and in the case of an aliphatic polyamide fiber, for example, 0.5 to 10 mm, preferably 1.0 to 8 mm (for example, 1.5 to 5 mm), Preferably, it may be about 2.0 to 4 mm (especially 2.5 to 3.5 mm).

  The average fiber diameter of the short fibers (B) may be 5 μm or more, for example, 5 to 50 μm, preferably 7 to 40 μm, and more preferably about 10 to 35 μm. If the fiber diameter is too small, the durability of the belt may be reduced.

The material of the short fiber (B) is not particularly limited. Examples of the short fiber (B) include polyolefin fiber (polyethylene fiber, polypropylene fiber, etc.), fluorine fiber (polytetrafluoroethylene fiber, etc.), vinyl alcohol type, and the like. Fibers (polyvinyl alcohol fibers, ethylene-vinyl alcohol copolymer fibers, vinylon, etc.), polyamide fibers (polyamide 6 fibers, polyamide 66 fibers, polyamide 46 fibers, etc., aliphatic polyamide fibers, aramid fibers, etc., etc. ), polyester fibers [polyethylene terephthalate (PET) fibers, polypropylene terephthalate (PPT) fibers, polytrimethylene terephthalate (PTT) fibers, poly _{C 2-4} alkylene such as polyethylene naphthalate (PEN) fibers _{C 6- 4} arylate fibers, polyarylate fibers, including full aromatic polyester fibers such as liquid crystal polyester fiber, polyphenylene ether fibers, polyetheretherketone fibers, polyethersulfone fibers, poly-p-phenylene benzobisoxazole (PBO) Synthetic fibers such as fibers and polyurethane fibers; regenerated cellulose fibers such as rayon; semi-synthetic fibers such as cellulose ester fibers; natural fibers such as cellulose fibers (cellulose fibers derived from plants, animals or bacteria such as cotton, hemp, wool); Examples thereof include inorganic fibers such as glass fibers, carbon fibers, and metal fibers (steel fibers). Among these, synthetic fibers such as polyester fibers and polyamide fibers, inorganic fibers such as glass fibers and carbon fibers are widely used from the viewpoint of high modulus, and polyamide fibers (for example, polyamide 6 and polyamide) are used because of high oil resistance. An aliphatic polyamide fiber (aramid fiber) such as 66 is preferable, and an aromatic polyamide fiber (aramid fiber) is particularly preferable from the viewpoint that a high reinforcing (wear resistance) effect can be maintained even during running in oil.

  The ratio of the short fiber (B) is, for example, 1 to 30 parts by mass (for example, 2 to 30 parts by mass), preferably 2 to 10 parts by mass, and more preferably 3 to 9 parts per 100 parts by mass of the rubber component (A). It is about part by weight (particularly 4 to 8 parts by weight). If the proportion of short fibers is too small, the durability of the belt may be lowered.If the proportion is too large, the flexibility of the coat layer is lowered, the meshing position cannot be adjusted due to deformation, and the coat layer is greatly damaged. There is a risk of becoming.

(C) Other additives The rubber composition may contain various conventional additives (or compounding agents) as necessary. Examples of additives include vulcanizing agents or crosslinking agents [for example, oximes (such as quinonedioxime), guanidines (such as diphenylguanidine), metal oxides (such as magnesium oxide and zinc oxide), and organic peroxides (such as Diacyl peroxide, peroxy ester, dialkyl peroxide, etc.)], vulcanization aid, vulcanization accelerator, vulcanization retarder, reinforcing agent (such as silicon oxide such as carbon black and hydrous silica), metal oxide ( For example, zinc oxide, magnesium oxide, calcium oxide, barium oxide, iron oxide, copper oxide, titanium oxide, aluminum oxide), filler (clay, calcium carbonate, talc, mica, etc.), plasticizer, softener (paraffin oil) Oils such as naphthenic oil), processing agents or processing aids (stearic acid, stearic acid) Metal salts, waxes, paraffins, etc.), anti-aging agents (aromatic amines, benzimidazole anti-aging agents, etc.), adhesion improvers [resorcin-formaldehyde cocondensates, melamine resins such as hexamethoxymethyl melamine, etc. Cocondensates (resorcinol-melamine-formaldehyde cocondensate, etc.)], colorants, tackifiers, coupling agents (silane coupling agents, etc.), stabilizers (antioxidants, UV absorbers, heat stabilizers, etc.) ), Lubricants, mold release agents, flame retardants, antistatic agents and the like. These additives can be used alone or in combination of two or more.

  The ratio of the other additive is 150 parts by mass or less, for example, about 0.1 to 100 parts by mass, preferably about 1 to 50 parts by mass with respect to 100 parts by mass of the rubber component (A) depending on the type. For example, the ratio of the vulcanizing agent or the crosslinking agent is 0.1 to 20 parts by weight, preferably 0.5 to 10 parts by weight, more preferably about 1 to 5 parts by weight with respect to 100 parts by weight of the rubber component (A). It is. The ratio of the reinforcing agent is 1 to 50 parts by mass, preferably 5 to 40 parts by mass, and more preferably about 10 to 30 parts by mass with respect to 100 parts by mass of the rubber component (A). The proportion of the antioxidant is 0.1 to 20 parts by mass, preferably 0.5 to 10 parts by mass, and more preferably about 1 to 5 parts by mass with respect to 100 parts by mass of the rubber component (A).

  Furthermore, in the present invention, since the wear resistance of the coat layer is high, the rubber composition may be a composition that does not contain a release agent or a lubricant among the additives, and particularly includes a fluororesin. The composition may not be present.

(D) Characteristics of Coat Layer The toothed belt of the present invention is only required to have the surface of the tooth cloth covered with the coat layer, and at least the transmission surface is preferably covered with the coat layer. In view of the above, it is particularly preferable that the entire surface of the tooth cloth (transmission surface and non-transmission surface) is formed of the coating layer. The coverage by the coat layer may occupy 50% or more, preferably 80% or more, more preferably 90% or more (particularly 100%) with respect to the entire surface (transmission surface and non-transmission surface) of the tooth cloth. ).

  The average thickness of a coat layer is 10 micrometers or more, for example, 10-500 micrometers, Preferably it is 20-200 micrometers, More preferably, it is about 30-100 micrometers. If the coat layer is too thin, the durability of the belt may be reduced. The coat layer may be partially impregnated in the tooth cloth in order to improve adhesion with the tooth cloth. In the present specification and claims, when the coat layer is impregnated in the tooth cloth, the impregnated portion is also included in the thickness of the coat layer.

  In the present specification and claims, the method for measuring the average thickness of the coat layer may be a method of observing a cross section of the toothed belt near the tooth cloth surface with a scanning electron microscope (SEM).

[Toothed belt]
The toothed belt of the present invention can use a conventional toothed belt except for the coat layer. For example, the shape of the toothed belt is not limited to the structure shown in FIG. 1, and a plurality of toothed belts are formed on at least one surface of the belt at a predetermined interval in the longitudinal direction of the belt and can mesh with a toothed pulley. What is necessary is just to have a tooth part or a convex part. The cross-sectional shape of the tooth portion or the convex portion (the cross-sectional shape in the longitudinal direction or the width direction of the belt) is not limited to the trapezoidal shape. (Triangle, quadrangle (rectangle, etc.), etc.) may be used. Moreover, the space | interval of the tooth | gear part or convex part adjacent to a longitudinal direction may be 1-10 mm, for example, Preferably it may be about 2-8 mm according to the form of a tooth-like pulley.

(Belt body)
The rubber composition forming the belt main body (tooth part and back part) may be a conventional rubber composition used in a toothed belt, and different rubber compositions as long as the adhesion between the tooth part and the back part is not impaired. The same rubber composition may be sufficient. Usually, the tooth part and the back part often contain the same series of rubbers (for example, rubbers belonging to a diene rubber and different kinds) or the same kind of rubber components (for example, the same kind of diene rubbers). From the viewpoint of oil resistance, hydrogenated nitrile rubber is preferable. As the additive, the additive exemplified in the section of the rubber composition of the coat layer can be blended.

(Core)
As the fiber forming the core wire, the fiber of the material exemplified for the short fiber can be used. The said fiber can be used individually or in combination of 2 or more types. Among the fibers, the fibers forming the core wire are, for example, synthetic fibers such as polyester fibers and polyamide fibers (such as aramid fibers), inorganic fibers such as glass fibers and carbon fibers from the viewpoint of low elongation and high strength. Are generally used, and glass core wires and aramid core wires are generally used. The composition of the glass core is not particularly limited, and may be E glass, S glass (high strength glass), C glass, or the like.

  As the core wire (tensile body), a multifilament yarn twisted cord (for example, various twists, single twists, Lang twists, etc.) can be used. The thickness of the filament, the number of filaments converged and the number of strands are not particularly limited, and the average wire diameter (fiber diameter of the twisted cord) of the core wire is, for example, 0.5 to 3 mm, preferably 0.6 to 1 mm, more preferably May be about 0.7 to 0.8 mm.

  The plurality of core wires may be embedded at a predetermined interval (or pitch) (or at equal intervals) in the width direction of the belt. The interval (spinning pitch) between adjacent core wires may be, for example, about 0.5 to 2 mm, preferably about 0.8 to 1.5 mm, depending on the diameter of the core wires.

  The core wire may be subjected to adhesion treatment with various adhesion treatment agents (for example, epoxy compounds, isocyanate compounds, etc.) in order to improve the adhesion with the rubber component. You may surface-treat with a coating agent etc. A glass fiber or the like may be coated with a protective agent (such as the sizing agent, the RFL treatment liquid, or the overcoat agent) to suppress breakage of the glass fiber due to bending.

(Tooth cloth)
A tooth cloth is coated or laminated on the tooth portion of the toothed belt which is the pulley contact surface, and the tooth cloth is integrated with the tooth portion.

  As the fibers forming the wefts and warps of the tooth cloth, the fibers of the materials exemplified in the section for short fibers can be used. The said fiber can be used individually or in combination of 2 or more types. Among the above fibers, fluorine-based fibers (such as polytetrafluoroethylene fibers), polyester fibers (such as PET fibers), polyamide fibers (such as aliphatic polyamide fibers such as polyamide 66, aramid fibers), natural fibers such as cotton, and rayon Regenerated cellulose fiber, polyparaphenylene benzobisoxazole (PBO) fiber, polyurethane fiber, etc. are widely used. In particular, at least polyamide fibers (aliphatic polyamide fibers such as polyamide 66, aramid fibers, etc.) and fluorine fibers (polytetrafluoroethylene fibers) are preferably used in order to increase the life of the belt even when used under severe conditions. The

  The form of the fiber is not particularly limited, and may be either a filament yarn or a spun yarn, and may be a twisted yarn, a mixed twisted yarn, a blended yarn, or the like of a single composition fiber. For example, a mixed twisted yarn in which a highly elastic urethane fiber is combined with a low elasticity fluorine fiber may be used.

  The average fiber diameter of the fibers (or threads) constituting the tooth cloth may be, for example, about 5 to 100 μm, preferably about 10 to 50 μm. Moreover, the average fiber diameter (thickness) of the yarn (twisted yarn) formed of fibers may be, for example, about 100 to 2000 dtex, preferably about 300 to 1500 dtex for weft yarns, and 50 to 1000 dtex for warp yarns, preferably 100. It may be about ˜500 dtex.

  The woven structure (woven structure) of the tooth cloth may be a structure such as a twill weave (oblique fabric), a satin weave (lion fabric, satin), or a plain weave. Such a woven structure is useful for coating the coat layer. The twill and satin weave structures have fewer contact points of fibers (or yarns) than the plain weave structures, and the adhesiveness with the coat layer seems to be higher.

  The density of the wefts (lines / cm) may be, for example, about 5 to 50, preferably about 15 to 35 (particularly 20 to 30), and the density of the warps (lines / cm) is, for example, 10 to 300, preferably About 20-100 (especially 25-50) may be sufficient.

  The average thickness of the tooth cloth is not particularly limited, and may be, for example, about 0.3 to 1.5 mm, preferably about 0.5 to 1.3 mm, and more preferably about 0.6 to 1.2 mm.

  In order to enhance the adhesion between the belt body (tooth portion and back portion) and the tooth cloth, the tooth cloth may be subjected to an adhesion treatment. Examples of the adhesion treatment include a treatment liquid containing a reactive adhesion component such as an epoxy compound (or resin), an isocyanate compound (or polyisocyanate), a silane coupling agent, and an organic solvent (toluene, xylene, methyl ethyl ketone, etc.). A method of immersing the cloth; a method of immersing the tooth cloth in an aqueous treatment liquid such as an RFL treatment liquid; a rubber composition obtained by dissolving the rubber composition in an organic solvent; Examples thereof include a method of impregnating and adhering a rubber composition to a cloth. These methods can be performed alone or in combination, and the processing order and the number of processing are not particularly limited. In order to further improve the adhesion between the adhesive-treated tooth cloth and the rubber of the belt body, the tooth cloth and the rubber composition are passed through a calender roll, and the rubber composition of the belt body is imprinted on the tooth cloth. You may perform the process which laminates | stacks a rubber composition on the adhesion surface side with a tooth | gear part among cloth. The rubber composition impregnated in the tooth cloth (or the rubber composition imprinted on the tooth cloth or laminated on the adhesive surface with the tooth part) is the same kind as the rubber composition forming the belt body (tooth part and back part). Alternatively, different rubber compositions can be used. As the rubber composition, the same rubber composition as that of the belt body (tooth portion and back portion) is often used.

  The RFL treatment liquid is a mixture in which an initial condensate of resorcin and formalin is mixed with latex, and the latex is not particularly limited. For example, styrene-butadiene-vinylpyridine terpolymer, hydrogenated nitrile rubber Chlorosulfonated polyethylene, epichlorohydrin rubber, and the like.

[Method of manufacturing toothed belt]
The toothed belt of the present invention can be produced by a conventional method after the surface of the tooth cloth is coated with a coat layer. As a coating method of the coating layer, a conventional method, for example, a method of soaking (immersion processing) with a rubber composition (for example, rubber paste containing a solvent) for forming the coating layer, a coating layer using a calendar roll A method of laminating a sheet-like rubber composition (unvulcanized rubber sheet) for forming a rubber, a friction method of rubbing the rubber paste on the surface of a tooth cloth, and the like can be used. Of these methods, from the viewpoint of simplicity and the like, a method of immersing a tooth cloth in rubber paste is preferable.

  In the dipping method, at least a part of the surface of the tooth cloth may be immersed, or at least the entire surface, particularly the entire tooth cloth may be immersed. The contact temperature (or impregnation temperature) is not particularly limited, and the tooth cloth and / or rubber paste may be heated or heated to about 30 to 70 ° C., but is usually room temperature in many cases. Further, the contact (or impregnation) of the rubber paste with the tooth cloth may be performed under normal pressure, under pressure or under reduced pressure. For example, the rubber paste may be introduced into a container for storing the tooth cloth under reduced pressure. .

  The contact time (or impregnation time) between the tooth cloth and the rubber paste is not particularly limited, and may be, for example, about 1 minute to 6 hours. For example, in order to allow the silane compound to penetrate into the tooth cloth, the contact time is, for example, 10 Minutes to 3 hours, preferably about 30 minutes to 2 hours may be sufficient.

  The processing of the tooth cloth with the rubber paste may be performed in any step of the belt forming process. For example, (a) the tooth cloth is previously coated with the rubber glue (or the sheet-like rubber composition) to form the belt. (B) The tooth cloth part of the vulcanization sleeve obtained by vulcanizing the belt body provided with the tooth cloth may be coated with rubber paste (or a sheet-like rubber composition), (c) The tooth cloth part of the toothed belt prepared by cutting the vulcanized sleeve into a predetermined width may be coated with rubber paste (or a sheet-like rubber composition).

When rubber paste is used, the coating amount (or adhesion ratio) of the rubber paste to the tooth cloth is, for example, ^{2 to} 50 mg / cm ² , preferably 3 to 30 mg / cm ² , more preferably, with respect to the unit area of the tooth cloth. it is a 4~20mg / cm ² about.

  The rubber paste usually contains an organic solvent (such as aliphatic ketones such as methyl ethyl ketone). The ratio of the organic solvent is 100 to 1000 parts by mass, preferably 300 to 800 parts by mass, and more preferably about 400 to 600 parts by mass with respect to 100 parts by mass of the rubber composition.

  The toothed belt can be formed by a known method. For example, a step of winding a canvas forming a tooth cloth around a cylindrical mold having a plurality of recesses corresponding to tooth portions of a toothed belt, and a cylindrical cord around which a tooth cloth is wound, a cord forming a cord Unwrapped rubber for forming a back portion and a tooth portion, a step of winding at a predetermined pitch (predetermined pitch with respect to the axial direction of the cylindrical mold) in the longitudinal direction (circumferential direction) of the cylindrical mold, a step of spinning spirally A step of winding a sheet to form an unvulcanized sleeve (unvulcanized laminate), and transferring the cylindrical mold around which the unvulcanized sleeve is wound into a vulcanizing can, and heating and pressurizing the rubber sheet. Is pressed into a mold groove (outer mold groove) and vulcanized to form teeth (step of forming a vulcanized laminate having teeth), and the obtained sleeve-shaped molded body has a predetermined cut width. According to Through the step of cutting by the cutting blade Te can produce toothed belts. As described above, the coating treatment of the coat layer on the tooth cloth may be performed in any of the steps.

  Hereinafter, the present invention will be described in more detail based on examples, but the present invention is not limited to these examples.

[Raw materials]
HNBR complex 1: complex of zinc dimethacrylate and HNBR (mass ratio of 50/50), “ZSC2095” manufactured by Nippon Zeon Co., Ltd., iodine value 7 mg / 100 mg or less, bound AN amount 36.2 mass%
HNBR complex 2: complex of zinc dimethacrylate and HNBR (mass ratio of 50/50), “ZSC2195” manufactured by Nippon Zeon Co., Ltd., iodine value 11 mg / 100 mg, bound AN amount 36.2 mass%
HNBR complex 3: complex of zinc dimethacrylate and HNBR (mass ratio of 50/50), “ZSC4195” manufactured by Nippon Zeon Co., Ltd., iodine value 15 mg / 100 mg, bound AN amount 18.6 mass%
HNBR1: “Zetpole 2000” manufactured by Nippon Zeon Co., Ltd., iodine value of 7 mg / 100 mg or less, bound AN amount of 36.2% by mass
HNBR2: “Zetpole 2010” manufactured by Nippon Zeon Co., Ltd., iodine value 11 mg / 100 mg, amount of bound AN 36.2% by mass
HNBR3: “Zetpole 4310” manufactured by Nippon Zeon Co., Ltd., iodine value 15 mg / 100 mg, bound AN amount 18.6% by mass
HNBR Latex: “Latex” manufactured by Nippon Zeon Co., Ltd., concentration 40% by mass
Polyamide short fiber 1: “Technola short fiber” manufactured by Teijin Limited, cut length: 1 mm, fiber diameter: 12.5 μm
Polyamide short fiber 2: “Technola short fiber” manufactured by Teijin Limited, cut length: 0.3 mm, fiber diameter: 12.5 μm
Polyamide short fiber 3: “66 nylon short fiber” manufactured by Nishiyori Co., Ltd., cut length 1 mm, fiber diameter 25 μm
Polyamide short fiber 4: “66 nylon short fiber” manufactured by Nishiyori Co., Ltd., cut length: 3 mm, fiber diameter: 25 μm
Silica: “Ultra Gil VN-3” manufactured by Evonik Degussa Japan
Amine-based anti-aging agent: “NOCRACK AD-F” manufactured by Ouchi Shinsei Chemical Co., Ltd.
Organic peroxide: "Perbutyl P" manufactured by NOF Corporation
RF condensate: resorcin / formalin = 1/1 (molar ratio)
Vinylpyridine / styrene / butadiene terpolymer latex: solid content 4% by mass.

[Abrasion test of rubber composition of coat layer]
Rubber compositions (A-1) to (A-11) were prepared by kneading the rubber compositions having the formulation shown in Table 1. About the obtained rubber composition, it vulcanized on the vulcanization conditions at the time of manufacturing the below-mentioned toothed belt, and produced the test piece. After the obtained specimen was immersed in engine oil (genuine engine oil “Ultra G1” manufactured by Honda Motor Co., Ltd.) for 7 days at 150 ° C. and the volume change rate was confirmed, in accordance with JIS L1096, Taber abrasion test was carried out (wear wheel H-18, load 1000 g, rotation speed 500 times). The obtained results are shown in Table 1.

  As is apparent from Table 1, the rubber composition (A-10) containing no short fiber and having a hydrogenated nitrile rubber having an amount of bonded AN of less than 32% by mass is 150 ° C. in engine oil after 7 days. The volume change rate greatly deviated from the range of ± 3%, the oil resistance was poor, and the wear amount was also large.

  In addition, the rubber composition (A-8) containing no short fibers or the rubber composition (A-9) having a short fiber length has a relatively large volume change rate and wear amount.

  Furthermore, the rubber composition (A-11) in which the bonded AN amount of hydrogenated nitrile rubber is less than 32% by mass greatly deviates from the range of ± 3% of the volume change rate, is inferior in oil resistance, and has a slightly large wear amount. It was.

  On the other hand, the rubber compositions (A-1) to (A-7) within the scope of the present invention had a small volume change rate and a small amount of wear, and had good oil resistance and wear resistance.

[Manufacture of toothed belt]
(Rubber paste for coat layer)
15 parts by mass of the coating rubber composition shown in Table 1 and 85 parts by mass of methyl ethyl ketone (MEK) were mixed and dissolved to prepare a rubber paste for a coating layer.

(Coating on tooth cloth)
As the tooth cloth, a two-color double twill weave having a 1/3 twill weave on the front side and a 2/2 twill weave on the back side was used. In this two-color double twill fabric, the warp is polyamide 66 yarn, the front weft is PTFE fiber (Toyoflon, Toray Industries, Ltd., 1330 dtex) and urethane elastic yarn, and the back weft is polyamide 66 yarn. And urethane elastic yarn. Then, the tooth cloth is immersed in the RFL treatment liquid shown in Table 2 and dried to perform RFL treatment, and then the tooth cloth is immersed in the rubber paste and coated on the surface of the tooth cloth. A rubber composition for forming a coat layer was adhered to the surface.

(Rubber composition constituting the teeth and back of the belt body)
The rubber composition described in Example 1 of Patent Document 3 (Japanese Patent Laid-Open No. 2012-197857) was used.

(Core)
A treatment cord with a rubber film was used as the core wire. That is, one bundle of ECG-150 glass fibers was prepared, and three glass fibers were aligned, soaked in an RFL treatment solution shown in Table 3, and then heat treated at 230 ° C. for 1 minute. The obtained heat-treated raw yarn was twisted 120 times / m to form a glass fiber strand, and after 11 strands were twisted into various strands, the strand was immersed in the rubber paste shown in Table 3 at 160 ° C. By heat-treating for 3 minutes, a treated cord with a rubber film used as a core wire was obtained.

(Production of belt)
The rubber composition constituting the belt body (tooth portion and back portion) was passed through a roll to produce an unvulcanized rubber sheet. First, on a flat mold having a tooth-shaped recess, a tooth cloth having a rubber composition for a coat layer attached on the surface and an unvulcanized rubber sheet for forming a tooth part are stacked, and the obtained laminate is heated and By pressurizing, the tooth cloth and the unvulcanized rubber sheet were filled in the tooth mold recess, and the tooth part whose surface was covered with the tooth cloth was preformed. Next, the preform of the tooth part was wound around a cylindrical mold having a tooth mold recess provided on the outer periphery so that the tooth part was fitted into the tooth mold recess. Further, a core wire was wound spirally on the obtained wound body, and an unvulcanized rubber sheet for forming a belt back portion was further wound on the core wire. The entire wound body is put in a vulcanizing can and vulcanized under the conditions of 170 ° C. and 0.8 MPa, so that the rubber layer of the tooth part is integrated with the inner periphery of the rubber layer of the back part of the belt. A vulcanization sleeve was formed. Finally, this vulcanized sleeve was cut so as to be cut into a 10 mm width to produce a toothed belt having a belt size of 106 MY (number of teeth: 106, tooth type MY, belt width: 10 mm).

(Durability evaluation of toothed belt)
The obtained toothed belt was subjected to an endurance test using a triaxial lubrication running test machine shown in FIG. 3 to measure the belt running life. That is, the toothed belt A is suspended on a drive pulley 10 composed of a toothed pulley with 22 teeth, a driven pulley 11 composed of a toothed pulley with 44 teeth, and a tension pulley 12 composed of a flat pulley. The vehicle was run under the conditions of the number of revolutions: 3600 rpm, load: no load, and ambient temperature: room temperature. Further, 150 ° C. engine oil (Ultra G1) was constantly injected into the toothed belt A spanned between the driving pulley 10 and the driven pulley 11 from the nozzle in an amount of 100 cc / min. A triaxial lubrication running test is conducted in this way. When the rubber layer on the teeth and the back of the belt cracks, when the teeth are chipped (missed), when the tooth cloth peels off, The earliest time point at which the belt was cut was determined as the belt running life. The results are shown in Table 4.

  In the toothed belts of Examples 1 to 7, the coat layer is a composition in which polyamide short fibers having a fiber length of 1 to 3 mm are blended with hydrogenated nitrile rubber having a bonded AN amount of 32 to 40% by mass. The swelling resistance (oil resistance) and wear resistance to the lubricating oil were improved, the coating layer was not peeled off even during running in oil, the amount of wear on the tooth cloth was reduced, and a longer life could be achieved.

  On the other hand, in Comparative Examples 1 and 2, since the short fiber is not included or the short fiber length is blended with the short polyamide fiber, the wear resistance and oil resistance performance are inferior to the coat layer used in the examples. The coat layer easily peeled off during running, and the wear of the tooth cloth increased and the durability was low.

  In Comparative Examples 3 to 4, since the amount of hydrogenated nitrile rubber bonded AN was small and the oil resistance was low, the coated rubber was peeled off significantly during running in oil, and the tooth cloth was greatly worn and the durability was low.

  The toothed belt of the present invention is combined with a toothed pulley in various fields where synchronization between input and output is required, for example, power transmission of engines such as automobiles and motorcycles, power transmission of motors and pumps, It can be used for machinery such as automatic doors and automation machines, copying machines, and printing machines. In particular, it can be used as peripheral equipment (peripheral parts) such as a power transmission belt (timing belt or cogged belt) of an automobile engine.

DESCRIPTION OF SYMBOLS 1 ... Back part 2 ... Tooth part 3 ... Core wire 4 ... Tooth cloth 5 ... Short fiber 6 ... Warp thread 7 ... Weft

Claims (12)

  A toothed belt including a tooth part meshable with a toothed pulley, a tooth cloth covering the tooth part, and a coat layer covering the tooth cloth, wherein the coat layer has a combined acrylonitrile amount of 32 to 40 mass. A toothed belt formed of a rubber composition containing a rubber component (A) containing 1% hydrogenated nitrile rubber (a) and short fibers (B) having an average fiber length of 0.5 mm or more.   The toothed belt according to claim 1, wherein at least a part of the hydrogenated nitrile rubber (a) is complexed with an unsaturated carboxylic acid metal salt to form a complex (a1).   In the hydrogenated nitrile rubber (a), the mass ratio between the complex (a1) and the non-complex (a2) not complexed with the unsaturated carboxylic acid metal salt is determined as the complex (a1) / non-complex (a2). The toothed belt according to claim 2, wherein 10/90 to 99/1.   The toothed belt according to claim 3, wherein a mass ratio of the composite (a1) and the non-composite (a2) is composite (a1) / non-composite (a2) = 60/40 to 80/20.   The toothed belt according to any one of claims 1 to 4, wherein the iodine value of the hydrogenated nitrile rubber (a) is 8 to 13 mg / 100 mg.   The toothed belt according to any one of claims 1 to 5, wherein the short fibers (B) have an average fiber length of 0.5 to 5 mm.   The toothed belt according to any one of claims 1 to 6, wherein the short fibers (B) are polyamide fibers.   The toothed belt according to claim 7, wherein the polyamide fiber is an aromatic polyamide fiber.   The ratio of a short fiber (B) is 1-30 mass parts with respect to 100 mass parts of rubber components (A), The toothed belt in any one of Claims 1-8.   The ratio of a short fiber (B) is 2-10 mass parts with respect to 100 mass parts of rubber components (A), The toothed belt in any one of Claims 1-9.   The toothed belt according to any one of claims 1 to 10, wherein the rubber composition does not contain a fluororesin.   The toothed belt according to any one of claims 1 to 11, wherein the coat layer has an average thickness of 10 µm or more.

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