JP2007309523A - Toothed belt - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a reinforcing fiber cord and a toothed belt using the reinforcing fiber cord improved in the retention rate of strength after bending fatigue by improving the heat resistance of the reinforcing fiber cord embedded and bonded in a rubber compound of the toothed belt. <P>SOLUTION: A tooth 3 and a back part 2 of the toothed belt A are composed of rubber compounding 15-40 pts.mass of unsaturated metal hydroxylate to the total polymer in hydrogenated nitrile rubber whose rate of hydrogenation is 80% or higher. The reinforcing cord 1 is formed of a cord composed of untwisted or twisted inorganic fiber treated with an RFL liquid containing hydrogenated nitrile rubber latex with alkylphenol formaldehyde resin added thereto and styrene-butadiene-vinylpyridine terpolymer rubber latex and further overcoat-treated with rubber cement formed by dissolving a chlorosulfonated polyethylene compound with a solution. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a toothed belt used for driving a camshaft of an automobile engine, driving of a camshaft and an injection pump, or synchronous transmission of a general industrial machine.

  Toothed belts that drive camshafts, injection pumps, oil pumps, water pumps, etc., for automobile engines, increase the load on the belt and increase the ambient temperature as the engine room becomes more compact with higher engine output Since the use environment of toothed belts has become particularly severe in recent years, further improvement in durability is required.

  Chloroprene rubber has been mainly used for conventional toothed belts, but cracking was observed earlier than the back rubber part under high atmospheric temperature. For this reason, recently, hydrogenated nitrile rubber developed as a heat-resistant polymer has been used for toothed belts. In addition, rubbers using peroxides in the vulcanization system and rubber blends using unsaturated carboxylic acid metal salts as hydrogenated nitrile rubbers are also used as a matrix for toothed belts. Accordingly, the method for bonding reinforcing fiber cords to hydrogenated nitrile rubber is also being improved.

  For example, Patent Document 1 discloses a method for bonding a reinforcing fiber cord and a hydrogenated nitrile rubber composition. This is treated with a pretreatment liquid containing a nitrile rubber-modified epoxy resin and an alkylphenol formaldehyde resin, followed by treatment with an RFL liquid comprising a nitrile rubber compound or hydrogenated nitrile rubber latex. Also, there is a method of treating with an RFL solution comprising a carboxyl group-containing acrylonitrile-butadiene rubber latex disclosed in Japanese Patent Publication No. 60-24131. In addition, a method of treating with an RFL solution comprising vinyl pyridine rubber latex, chlorosulfonated polyethylene rubber latex, styrene / butadiene rubber latex, and the like are also disclosed.

  Thus, although the water resistance of the reinforcing fiber cord and the hydrogenated nitrile rubber (hereinafter referred to as H-NBR) has been sufficiently improved by the treatment method described above, these treated reinforcing fiber cords have been improved. It is known that when a toothed belt using a cord as a core wire is subjected to heat-resistant bending at a high ambient temperature, the RFL layer deteriorates early and the core wire undergoes bending fatigue. Further, in the case of hydrogenated nitrile rubber using sulfur in the vulcanization system of H-NBR, it has been pointed out that cracks occur in the back rubber portion earlier than the peroxidized portion, leading to the belt life. In addition, in the H-NBR peroxide vulcanization system, in the case of the conventional RFL liquid, the RFL reacts with the peroxide of the vulcanizing agent and the deterioration of the RFL is accelerated. In the case of vulcanized hydrogenated nitrile rubber made of peroxide, the radicals move to the RFL of the cord during vulcanization. However, there is a problem that it tends to deteriorate early.

JP 2000-212878 A

  The present invention relates to a reinforcing fiber cord that improves the heat resistance of a reinforcing fiber cord bonded and embedded in a rubber compound of a toothed belt and improves the strength retention after bending fatigue, and a toothing using the same The object is to provide a belt.

The toothed belt according to claim 1 is embedded in a plurality of tooth portions based on rubber arranged at predetermined intervals along the longitudinal direction, a back portion continuous with the plurality of tooth portions, and the back portion. A toothed belt having a reinforcing fiber cord and a tooth cloth coated on the surface of the tooth part,
The tooth part and the back part are composed of a rubber in which an unsaturated carboxylic acid metal salt is blended in an amount of 15 to 40 parts by mass with respect to the total polymer in a hydrogenated nitrile rubber having a hydrogenation rate of 80% or more,
The reinforcing cord is made of non-twisted or twisted inorganic fiber, a hydrogenated nitrile rubber latex to which an alkylphenol formaldehyde resin is added and a styrene-butadiene-vinylpyridine terpolymer rubber latex. It is treated with an RFL solution, and further overcoated with a rubber paste prepared by dissolving a chlorosulfonated polyethylene compound in a solution.

  By setting the hydrogenation rate of the hydrogenated nitrile rubber to 80% or more, the heat resistance and ozone resistance of the hydrogenated nitrile rubber can be ensured. Further, by adding an unsaturated carboxylic acid metal salt to the hydrogenated nitrile rubber, the modulus (tensile modulus) and hardness can be increased. And in order to ensure a modulus (tensile modulus), cutting elongation, and higher tear strength and hardness, it is preferable to blend 15-40 parts by mass of the unsaturated carboxylic acid metal salt with respect to the total polymer.

  The toothed belt according to claim 2, wherein the weight ratio of the hydrogenated nitrile rubber latex to the styrene-butadiene-vinylpyridine terpolymer rubber latex contained in the RFL liquid is 60/40. It is characterized by being -90/10.

  The weight ratio of the hydrogenated nitrile rubber latex and the styrene-butadiene-vinylpyridine terpolymer rubber latex contained in the RFL solution is preferably 60/40 to 90/10. Heat resistance falls that a weight ratio is 60/40 or less. Moreover, water resistance falls that a weight ratio is 90/10 or more.

The toothed belt according to claim 3 is embedded in a plurality of tooth portions based on rubber arranged at predetermined intervals along the longitudinal direction, a back portion continuous with the plurality of tooth portions, and the back portion. A toothed belt having a reinforcing fiber cord and a tooth cloth coated on the surface of the tooth part,
The tooth portion and the back portion are blended with hydrogenated nitrile rubber having a hydrogenation rate of 80% or more in an amount of 5 to 15 parts by mass of the unsaturated carboxylic acid metal salt based on the total polymer, and the short fibers are the total polymer Composed of 1 to 20 parts by mass of rubber,
The reinforcing cord is made of non-twisted or twisted inorganic fiber, a hydrogenated nitrile rubber latex to which an alkylphenol formaldehyde resin is added and a styrene-butadiene-vinylpyridine terpolymer rubber latex. It is treated with an RFL solution, and further overcoated with a rubber paste prepared by dissolving a chlorosulfonated polyethylene compound in a solution.

  By setting the hydrogenation rate of the hydrogenated nitrile rubber to 80% or more, the heat resistance and ozone resistance of the hydrogenated nitrile rubber can be ensured. Further, by adding an unsaturated carboxylic acid metal salt and short fibers to the hydrogenated nitrile rubber, the modulus (tensile modulus) and hardness can be increased. And in order to ensure a modulus (tensile modulus), cutting elongation, higher tear strength and hardness, 5-15 parts by mass of unsaturated carboxylic acid metal salt is blended with respect to the total polymer, and short fibers are added. It is preferable to mix | blend 1-20 weight part with respect to a total polymer.

  The toothed belt according to claim 4 is the toothed belt according to claim 3, wherein the weight ratio of the hydrogenated nitrile rubber latex to the styrene-butadiene-vinylpyridine terpolymer rubber latex contained in the RFL liquid is 60/40. It is characterized by being -90/10.

  The weight ratio of the hydrogenated nitrile rubber latex and the styrene-butadiene-vinylpyridine terpolymer rubber latex contained in the RFL solution is preferably 60/40 to 90/10. Heat resistance falls that a weight ratio is 60/40 or less. Moreover, water resistance falls that a weight ratio is 90/10 or more.

  As described above, the present invention improves the heat resistance of the reinforcing fiber cord, improves the adhesive strength with the rubber compound, improves the strength retention after bending fatigue under a high ambient temperature, and increases the load The belt life due to the belt damage occurring below can be extended, and the durability of the belt can be greatly improved.

  Hereinafter, an example of an embodiment of the present invention will be described. The reinforcing fiber cord and the toothed belt according to the present invention are not limited to the following embodiments.

  FIG. 1 is an overall perspective schematic view of a toothed belt A according to the present embodiment. In FIG. 1, the toothed belt A is embedded in a plurality of tooth portions 3 based on rubber 5 arranged at predetermined intervals along the longitudinal direction, a back portion 2 continuous with the tooth portions 3, and the back portion 2. In this configuration, the reinforcing fiber cord 1 and the tooth cloth 4 coated on the surface of the tooth portion 3 are provided.

  There is no restriction | limiting in particular in the material of the rubber | gum 5 used as the base material of the tooth | gear part 3 and the back part 2, A suitable thing is suitably selected according to use conditions. In the case of toothed belts for automobile engines and various engines, H-NBR, CR, CSM, etc. having heat resistance and oil resistance are used. In addition to H-NBR, CR, and CSM, toothed belts used in general industrial machines include NBR, EPDM, ethylene propylene copolymer (EPR), SBR, isopropylene rubber (IR), and natural rubber (NR). Any of fluorine rubber, silicon rubber, etc. can be used. In this embodiment, the rubber 5 is a rubber formed by crosslinking H-NBR or a compounded rubber in which an unsaturated carboxylic acid metal salt is blended with H-NBR and either an organic peroxide or a sulfur compound. It illustrates about.

  H-NBR has a hydrogenation rate of 80% or more, and a hydrogenation rate of 90% or more is preferable in order to exhibit heat resistance and ozone resistance, but 92 to 98% is preferable. When the hydrogenation rate is 80% or less, H-NBR has extremely low heat resistance and ozone resistance. In consideration of oil resistance and cold resistance, the amount of bound acrylonitrile is preferably 20 to 45%. When the amount of bound acrylonitrile is 20% or less, the oil resistance is lowered, and when the amount of bound acrylonitrile is 45% or more, the cold resistance is lowered.

  Further, by adding an unsaturated carboxylic acid metal salt to this H-NBR, the modulus (tensile modulus) and hardness are increased, and the modulus (tensile modulus) and cutting elongation are higher. In order to ensure the tear strength and hardness, it is preferable to blend the unsaturated carboxylic acid metal salt with H-NBR in an amount of 15 to 40 parts by mass based on the total polymer as described above. Or 5-15 mass parts of unsaturated carboxylic acid metal salts can be mixed, and 1-20 mass parts can also be mix | blended with respect to the polymer component 100 for a short fiber.

  Here, the short fiber is preferably a high melting point that is difficult to melt at low temperatures during friction, or cotton, vinylon, aramid, inorganic fiber or the like that does not have a melting point. The length is preferably 5 mm or less. When the fiber length exceeds 5 mm, the rubber tends to be oriented when it is made into a rolled sheet with a calendar or an extruder, and when it becomes a belt, cracks are likely to occur early due to bending. The orientation direction of the short fibers is preferably the belt width direction, but may be the orientation in the belt length direction. When the blending amount of the short fibers is less than 1 part by mass, the effect of blending the short fibers does not appear. On the other hand, when the amount of short fibers exceeds 20 parts by mass, the Mooney viscosity of the rubber increases and cannot be processed (dispersion failure in the kneading process, cannot be rolled in the sheet rolling process, the surface skin is poor, the thickness does not come out, etc.), Is difficult to form with high accuracy.

  If the amount of the unsaturated carboxylic acid metal salt is less than 5 parts by mass, the rubber hardness does not reach a predetermined hardness. On the other hand, if it exceeds 40 parts by mass, the rubber hardness becomes too high, the belt rigidity becomes high, the bending fatigue property is inferior, and the belt life is shortened. Thus, by using the rubber | gum which mix | blended unsaturated carboxylic acid metal salt with H-NBR, the back surface hardness of the back part 2 can be 80 degree | times (JISA type hardness meter) or more. Since the back hardness can be 80 degrees (JISA type hardness meter) or more, preferably 85 degrees or more, deformation of rubber can be suppressed even when stress is applied.

  The unsaturated carboxylic acid metal salt is an ionic bond of an unsaturated carboxylic acid having a carboxyl group and a metal. Examples of the unsaturated carboxylic acid include monocarboxylic acids such as acrylic acid and methacrylic acid, maleic acid, fumaric acid, and itacone. Dicarboxylic acids such as acids are preferred, and the metals are beryllium, magnesium, calcium, strontium, barium, titanium, chromium, molybdenum, manganese, iron, cobalt, nickel, copper, silver, zinc, cadmium, aluminum, tin, lead, antimony Etc. can be used.

  The rubber 5 is constituted by being blended with either an organic peroxide or a sulfur compound after being blended as described above.

  The organic peroxide is not particularly limited, but may be any conventionally used one. For example, t-butyl hydroperoxide, 1,1,3,3-tetrabutyl hydroperoxide, p-menthane hydroperoxide, cumene Hydroperoxide, di-isopropylbenzene hydroperoxide, ditetrabutyl peroxide, dicumyl peroxide, dicumyl peroxide, dicumyl peroxide, dicumyl peroxide butyl c myl Peroxid), 1, 3-bis (tert-butyl peroxy isopropyl) benzene (1,3-bis (tert-butylperoxy isopropyl) benzen), trialkyl iso Woo rate (trialkyl isocyanurate) and the like.

  Examples of sulfur compounds include general sulfur and sulfur compounds, and examples of vulcanizing agents include thiurams, dithiocarbamates, sulphonamides, thiazoles, and the like. I can do it. An organic compound, a sulfur compound, and a vulcanizing agent may be used in combination.

  In the present embodiment example, glass fibers that are inorganic fibers are used for the reinforcing fiber cord 1 embedded in the back portion 2 configured using the rubber 5 as a base material as described above. Inorganic fibers include carbon fibers, metal fibers, glass fibers, and the like, and any of them can be used as a reinforcing fiber cord. The composition of the glass fiber may be either E glass or S glass (high-strength glass), and is a twisted cord in which filaments of glass fiber are twisted together. Three untwisted raw yarns are gathered together and the lower twist is 8 times / 10 cm, obtained by twisting the upper twist 12 times / 10 cm, and is not particularly limited by the thickness of the filament, the number of converging filaments and the number of strands. The reinforcing fiber cord 1 is not limited to the above-described twisted cord, and may be a non-twisted cord.

  This reinforcing fiber cord 1 is treated with an untreated untwisted cord or a twisted cord with a solution in which an alkylphenol formaldehyde resin is added to an RFL solution in which an initial condensate of resorcin and formalin and a rubber latex are mixed. Heat treatment is performed at 0 ° C. Next, a chlorosulfonated polyethylene blend as an overcoat solution is immersed in a rubber paste dissolved in a solvent such as aromatic hydrocarbons such as toluene and xylene, treated, and heat treated at around 130-180 ° C.

  The RFL liquid is composed of a rubber latex in which a hydrogenated nitrile rubber latex to which an alkylphenol formaldehyde resin is added and a styrene-butadiene-vinylpyridine terpolymer rubber latex are mixed at a weight ratio of 75/25. . The RFL liquid is obtained by mixing an initial condensate of resorcin and formalin with the rubber latex. In this case, it is desirable that the molar ratio of resorcin and formalin is 3/1 to 1/3 in order to increase the adhesive force. The initial condensate of resorcin and formalin is mixed so that the resin content is 5 to 100 parts by weight with respect to 100 parts by weight of the rubber latex, and the total solid concentration is adjusted to 5 to 40%. Is done. Alkylphenol formaldehyde resin contains one or more phenols such as phenol, cresol, monohydric phenol such as chlorophenol, or polyhydric phenol such as resorcin, catechol, and one or more of formaldehyde, acetaldehyde, etc. Condensed in the presence of an acid or alkali catalyst.

  The hydrogenated nitrile rubber latex to which the alkylphenol formaldehyde resin in the RFL solution is added is superior in heat resistance compared to chlorosulfonated polyethylene latex and styrene butadiene rubber latex, and increases in hardness when thermally aged in a film form. The styrene-butadiene-vinylpyridine terpolymer rubber latex has a remarkably strong dipole or hydrogen bond interaction with the resorcin-formalin resin. In contrast, with styrene butadiene rubber latex, it has been confirmed that the interaction with the RF resin is very weak and only physical.

  In addition to the above-mentioned blend of RFL liquid, carboxyl hydrogenated nitrile rubber latex added with alkylphenol formaldehyde resin alone or carboxyl hydrogenated nitrile rubber latex and styrene-butadiene-vinylpyridine terpolymer rubber latex By treating with the RFL solution that is included, the heat resistance of the inorganic fibers and glass fibers that are reinforcing fiber cords and the adhesion between the filaments can be improved. In addition, the carboxyl hydrogenated nitrile rubber latex to which the alkylphenol formaldehyde resin in the RFL solution is added has more adhesiveness between the filaments of the inorganic fiber and the glass fiber than those to which the hydrogenated nitrile rubber latex is added. Can be improved.

  Nylon, aramid, polyester, polybenzoxazole, cotton, or the like is used as the material of the fiber material constituting the tooth cloth 4. The form of the fiber may be either a filament yarn or a spun yarn, and may be any one of a single composition twisted yarn, a mixed twisted yarn, or a blended yarn. Further, the weaving configuration may be any of twill weave, hand-woven, plain weave, and the like.

  This tooth cloth 4 is treated with an RFL solution, an isocyanate solution or an epoxy solution, and then subjected to a rubber paste treatment for impregnating and vulcanizing a rubber of the same quality as the rubber 5 used for the tooth portion 3. Specifically, a rubber paste prepared by dissolving a polymer used in the rubber 5 with a solvent is impregnated and adhered, dried, and vulcanized to obtain a rubberized canvas. Moreover, anti-aging agent can also be added as needed.

  As a solvent for dissolving the rubber 5, a solvent selected from methyl ethyl ketone (MEK), dimethyl sulfoxide, dimethylformamide, chloroform and the like can be used. The rubber paste obtained by dissolving the rubber 5 is preferably impregnated and adhered to the tooth cloth 4 by spraying or the like and vulcanized.

  As described above, the toothed belt A is configured, and the reinforcing fiber cord having improved heat resistance is bonded and embedded in the rubber compound of the toothed belt A, so that after bending fatigue under a high atmospheric temperature. Strength retention can be improved.

Next, the present invention will be specifically described with reference to examples.
(Example)
The reinforcing fiber cord was subjected to the treatment shown in Table 1 to obtain A-1, A-2, and A-3. The RFL treatment in Table 1 was performed by immersing three 3.7d untwisted raw yarns made of glass fiber filament groups in the RFL liquids B-1, B-2, and B-3 shown in Table 2. Thereafter, heat treatment was performed at 230 to 280 ° C. The overcoat treatment with the rubber glue shown in Table 1 is prepared by subjecting the rubber glue C-1 shown in Table 3 to a single twist cord in the S direction and the Z direction at a twist number of 8 times / cm. Then, 11 to 13 of these were aligned, and the one twisted at 12 times / cm was immersed and heat-treated at around 130 to 180 ° C.

  Next, a 2 / 2-folded tooth cloth D-1 shown in Table 4 is bonded to a die having 105 teeth of STPD tooth profile for belt preparation, and the tooth cloth is wound around the metal mold, and then shown in Table 1. The glass fiber cord is wound from above the tooth cloth of the mold around which the tooth cloth is wound, and further, the rubber sheet E-1 composed of the H-NBR rubber composition shown in Table 5 is wound, and then put into the vulcanizing can. Then, after forming a tooth profile by a normal pressure method, pressure vulcanization was performed at 109 ° C. for 20 minutes, and the back surface of the belt was polished to a certain thickness and cut to a certain width to obtain a running toothed belt. .

  The produced belt has a belt width of 19.1 mm, a belt tooth profile STPD, 105 teeth, and a tooth pitch of 8.000 mm, and is usually indicated as S8M. Next, a running test was performed using the obtained toothed belt. As a running test apparatus, a test apparatus is used in which a toothed belt is attached to a 21-tooth driving pulley 10 and a 42-tooth driven pulley 11 shown in FIG. 2 and a flat pulley 12 having a diameter of 52 mm is brought into contact with the back surface. A running test for 1000 hours was performed under the conditions of an atmospheric temperature of 130 ° C., a load of 3.67 kw, an initial tension of 147 N, and a driving side rotational speed of 7200 rpm. After completion of the test, the removed toothed belt was cut to a length of 250 to 300 mm to form a strip, which was used as a tensile test piece. Next, the belt strength of the tensile test piece was measured at a tensile speed of 50 mm / min, and divided by the value measured for the belt strength before the running test at a tensile speed of 50 mm / min, to determine the strength retention. This was defined as the strength retention after bending fatigue. Table 6 summarizes the results of the strength retention after bending fatigue of each belt.

  From Table 6, the RFL solution containing hydrogenated nitrile rubber latex to which alkylphenol formaldehyde resin was added and styrene-butadiene-vinylpyridine terpolymer rubber latex from Comparative Example 1 treated with ordinary RFL treatment solution was used. The strength retention after bending fatigue of Example 2 in which the hydrogenated nitrile rubber in the treated RFL treatment liquid treated in Example 1 or Example 1 was replaced with carboxyl hydrogenated nitrile rubber was improved. Recognize. Further, it is conceivable that the belt life due to belt damage that occurs under a high load will be extended by improving the strength retention rate.

1 is a schematic perspective view of a toothed belt according to the present invention. It is the schematic of the running test apparatus of a toothed belt.

Explanation of symbols

A Toothed belt 1 Reinforcing fiber cord 2 Back 3 Tooth 4 Tooth cloth 5 Rubber

Claims (4)

A plurality of tooth parts based on rubber arranged at predetermined intervals along the longitudinal direction, a back part continuous with the plurality of tooth parts, a reinforcing fiber cord embedded in the back part, and a surface of the tooth part A toothed belt having a tooth cloth coated thereon,
The tooth part and the back part are composed of a rubber in which an unsaturated carboxylic acid metal salt is blended in an amount of 15 to 40 parts by mass with respect to the total polymer in a hydrogenated nitrile rubber having a hydrogenation rate of 80% or more,
The reinforcing cord is made of non-twisted or twisted inorganic fiber, a hydrogenated nitrile rubber latex to which an alkylphenol formaldehyde resin is added and a styrene-butadiene-vinylpyridine terpolymer rubber latex. A toothed belt that is treated with an RFL solution and further overcoated with a rubber paste prepared by dissolving a chlorosulfonated polyethylene compound in a solution.   The weight ratio of the hydrogenated nitrile rubber latex and the styrene-butadiene-vinylpyridine terpolymer rubber latex contained in the RFL solution is 60/40 to 90/10. Toothed belt. A plurality of tooth parts based on rubber arranged at predetermined intervals along the longitudinal direction, a back part continuous with the plurality of tooth parts, a reinforcing fiber cord embedded in the back part, and a surface of the tooth part A toothed belt having a tooth cloth coated thereon,
The tooth portion and the back portion are blended with hydrogenated nitrile rubber having a hydrogenation rate of 80% or more in an amount of 5 to 15 parts by mass of the unsaturated carboxylic acid metal salt based on the total polymer, and the short fibers are the total polymer Composed of 1 to 20 parts by mass of rubber,
The reinforcing cord is made of non-twisted or twisted inorganic fiber, a hydrogenated nitrile rubber latex to which an alkylphenol formaldehyde resin is added and a styrene-butadiene-vinylpyridine terpolymer rubber latex. A toothed belt that is treated with an RFL solution and further overcoated with a rubber paste prepared by dissolving a chlorosulfonated polyethylene compound in a solution.   The weight ratio of the hydrogenated nitrile rubber latex and the styrene-butadiene-vinylpyridine terpolymer rubber latex contained in the RFL solution is 60/40 to 90/10. Toothed belt.

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