JP2006125630A - High-load transmission belt and center belt for high-load transmission belt - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a high-load transmission belt made of hydrogenerated nitrile rubber in which Aramid short fibers and carbon black are included in certain amounts so as to give the belt a sufficient hardness and unlikelihood to cause cracking with repetitive bending, capable of eliminating rattling between the center belts and the block, and having excellent resistance against bending and heat resistance. <P>SOLUTION: The high-load transmission belt 1 is structured so that a plurality of blocks 2 are fitted fast at the specified pitch in the longitudinal direction of the center belts 3a and 3b, wherein the rubber composition of the center belts 3a and 3b is 10 to 35 mass parts short fibers and 35 to 70 mass parts carbon black with respect to 100 mass parts hydrogenerated nitrile rubber, and the short fibers are composed of Aramid short fibers and Nylon short fibers, and the mixing quantity of Nylon short fibers is 5 to 15 mass parts. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a high load transmission belt in which blocks are fitted and fixed at a predetermined pitch along the longitudinal direction of the center belt, and more specifically, a center belt excellent in hardness, bending resistance and heat resistance, and a high load using the same. Related to transmission belt.

  The belt used in the belt type continuously variable transmission is used by being wound around a transmission pulley that changes the effective diameter of the pulley by adjusting the V groove width of the pulley and adjusts the transmission gear ratio. Because the side pressure from the belt increases, the belt must withstand a large side pressure. In addition to continuously variable speed applications, it is necessary to use a belt that can withstand a high load, especially for high-load transmission applications where the life of conventional rubber belts is too short.

  Among such belts, there is a tensile transmission type high-load transmission belt in which a block is fixed to the center belt to increase the strength in the belt width direction. A block made of an elastomer that is relatively harder than the elastomer used for the center belt is fixed to the center belt embedded in the elastomer using a fixing material such as a bolt or a rivet.

  The center belt of such a high load transmission belt is made of an elastomer such as rubber, and the block is fitted and fixed. By running the belt, the center belt repeatedly receives compressive and shearing forces from the block, generating permanent distortion in the elastomer forming the center belt, weakening the fixing force between the block and the center belt, and wobbling the block This can lead to rattling, which can lead to increased noise when the belt travels, and can cause the center belt to crack and cut.

  To date, for example, Patent Document 1 discloses a hydrogenated nitrile to which an unsaturated carboxylic acid metal salt and an organic peroxide are added in order to increase the strength of the center belt and prevent problems such as rubber sag, wear, and cracks. It is disclosed that a rubber composition in which short fibers are blended with rubber is used as a center belt. Further, it is described that sulfur is blended and used as a co-crosslinking agent of an organic peroxide which is a crosslinking agent.

  Further, in Patent Document 2, by mixing nylon short fibers and aramid short fibers into the shape-retaining rubber of the center belt, the center belt is given high elasticity to ensure durability, and the friction coefficient is reduced to reduce noise. It is disclosed to prevent the occurrence of the above.

  Patent Document 3 proposes a belt in which the hardness of the center belt is secured and the flexibility of the belt is improved by blending hydrogenated nitrile rubber with short aramid fibers and carbon black.

JP-A-5-272595 JP-A-6-2742 JP 2004-108420 A

  However, although the center belt as disclosed in Patent Document 1 has high hardness and can prevent the occurrence of trouble between the block and the center belt, it is weak against repeated bending and constitutes the center belt. This may lead to problems such as cracking due to bending of the rubber material.

  Further, although the center belt as disclosed in Patent Document 2 can reduce the occurrence of abnormal noise, the reinforcing effect of the center belt is reduced by the amount of blended nylon short fibers out of the amount of short fibers to be blended. Therefore, if the blending amount of the short fiber is increased too much in order to obtain a sufficient reinforcing effect, the short fiber acts as a foreign substance and causes cracking, so that the bending resistance is impaired.

  In Patent Document 3, although the bending resistance of the belt is improved as compared with the technique of Patent Document 1, it is not yet sufficient, and there are problems such as generation of cracks and cracks to breaks as the belt runs for a long time. It remained.

  Accordingly, the present invention provides a high load transmission belt and a center belt for a high load transmission belt that have sufficient hardness and heat resistance to be used as a center belt of a high load transmission belt, and also have sufficient performance regarding bending resistance. Let it be an issue.

  In order to solve the above-mentioned problems, claim 1 of the present invention provides a center belt and a high load transmission belt in which a plurality of blocks are fitted and fixed at a predetermined pitch along the longitudinal direction of the center belt. Is composed of 10 to 35 parts by mass of short fibers and 35 to 70 parts by mass of carbon black with respect to 100 parts by mass of hydrogenated nitrile rubber, and the short fibers are composed of aramid short fibers and nylon short fibers. The blending amount of the nylon short fiber is 5 to 15 parts by mass.

  In Claim 2, it is set as the high load power transmission belt whose compounding quantity of a short fiber is 25-35 mass parts with respect to 100 mass parts of hydrogenated nitrile rubber.

  In Claim 3, it is set as the high load power transmission belt whose compounding quantity of carbon black is 35-50 mass parts with respect to 100 mass parts of hydrogenated nitrile rubber.

  According to a fourth aspect of the present invention, the high-load transmission belt according to the first aspect of the present invention is such that the rubber of the center belt is sulfur-based.

  In the center belt used in the center belt and the high load transmission belt in which a plurality of blocks are fitted and fixed at a predetermined pitch along the longitudinal direction of the center belt, the rubber composition constituting the center belt is hydrogenated. 10 to 35 parts by mass of short fibers and 35 to 70 parts by mass of carbon black are blended with respect to 100 parts by mass of nitrile rubber. The short fibers are composed of aramid short fibers and nylon short fibers, and the amount of nylon short fibers is 5 It is -15 mass parts, It is characterized by the above-mentioned.

  In Claim 6, it is set as the center belt for high load transmission belts whose compounding quantity of a short fiber is 25-35 mass parts with respect to 100 mass parts of hydrogenated nitrile rubber.

  In Claim 7, it is set as the center belt for high load transmission belts whose compounding quantity of carbon black is 35-50 mass parts with respect to 100 mass parts of hydrogenated nitrile rubber.

  In the eighth aspect of the present invention, the rubber of the center belt is cross-linked as a center belt for a high load transmission belt that is sulfur-based.

  In the present invention, hydrogenated nitrile rubber is used to make it excellent in heat resistance, and has sufficient hardness to be used as a high load transmission belt by blending a predetermined amount of short fibers and carbon black, and By making some of the short fibers into nylon short fibers, the flexibility of the belt can be greatly improved while maintaining the hardness, and a belt with less failure such as cracking due to bending deterioration can be provided. .

  In Claims 2 and 6, by limiting the blending amount of the short fibers to a higher range, the center belt is kept high in hardness, and the high load transmission belt with less wobbling and backlash of the block with respect to the center belt is provided. can do.

  In Claims 3 and 7, the amount of short fibers is limited to a higher range and the amount of carbon black is limited to a lower range, so that the hardness is maintained high and block wobbling and rattling. It is possible to prevent the deterioration of the rubber by suppressing the heat generation during traveling and to make the belt longer in life.

  In claims 4 and 8, it is advantageous in that the flexibility of the center belt can be improved by using sulfur as the crosslinking agent.

  Hereinafter, the present invention will be specifically described with reference to the drawings.

  FIG. 1 is a schematic perspective view showing an example of a high load transmission belt 1 according to the present invention. The high-load transmission belt 1 of the present invention is fixed to two center belts 3a and 3b having the same width formed by embedding a core wire 5 in a spiral shape in an elastomer 4, and the center belts 3a and 3b. A plurality of blocks 2. Both side surfaces 2a, 2b of the block 2 are inclined surfaces that engage with the V-grooves of the pulleys, and receive the power from the driven pulleys to lock and fix the centers 3a, 3b. Pulling, the power of the driving pulley is transmitted to the driven pulley.

  As shown in FIG. 1, the block 2 includes an upper beam portion 11 and a lower beam portion 12, and a center pillar 13 in which the central portions of the upper and lower beam portions 11 and 12 are connected to each other. Fitting grooves 14 and 15 for fitting the center belts 3a and 3b are formed in 2b. Further, on the groove upper surface 16 and the groove lower surface 17 in the fitting groove 15, the ridge portions 20, 21 that engage with the ridge portions 18 provided on the upper surfaces of the center belts 3 a, 3 b and the ridge portions 19 provided on the lower surface. To be engaged.

  FIG. 2 shows an example of another belt. A pair of side pillars 32 and 33 extend upward from both ends of the beam portion 31, and the upper ends of the side pillars 32 and 33 respectively extend toward the center of the block 2. The extending lock portions 34 and 35 are provided so as to face each other. The beam portion 31, the side pillars 32 and 33, and the lock portions 34 and 35 form a fitting groove 30 into which the center belts 3a and 3b are fitted. The center belts 3a and 3b are inserted into the fitting groove 30 through the opening between the lock portions 34 and 35 and attached. Further, a convex portion 37 is provided on each of the lock portions 34 and 35 on the fitting groove 30 side, and this convex portion 37 is fitted into the concave portion 36 provided at a predetermined pitch on the center belts 3a and 3b. To do. As a result, the center belts 3a and 3b are not easily removed from the block 2 after being mounted.

  What is used as the elastomer 4 of the center belts 3a and 3b in the present invention is a hydrogenated nitrile rubber. More preferably, the short fiber is 10 to 35 parts by mass with respect to 100 parts by mass of the hydrogenated nitrile rubber. 35 to 70 parts by mass of carbon black, more preferably 35 to 50 parts by mass of carbon black, and 0.2 to 10 parts by mass of a crosslinking agent, and the short fibers are composed of aramid fibers and nylon fibers. In addition, the blending range of the nylon fiber is set to 5 to 15 parts by mass.

  In such a center belt, a material that can maintain the fitting and fixing force with the block over a long period of time is required, but by adding carbon black and short fibers to the hydrogenated nitrile rubber in the above range. The required hardness can be obtained, so that the fixing force by fitting the center belt with the block can be maintained, and by using hydrogenated nitrile rubber, heat resistance is excellent, and only aramid fibers are used as short fibers. In addition, since the nylon fiber is blended, cracks hardly occur even if the belt is repeatedly bent during running of the belt, and the life of the belt can be extended.

  Further, the crosslinking agent used may be either sulfur-based or peroxide-based. Examples of the sulfur system include sulfur, 4,4′-dithiobisdimorpholine, tetramethylthiuram disulfide, etc., and examples of the peroxide system include di-t-butyl peroxide, dicumyl peroxide, t-butyl cumyl peroxide, 1,1-t-butylperoxy-3,3,5-trimethylcyclohexane, 2,5-di-methyl-2,5-di (t-butylperoxy) hexane-3, bis (t-butylperoxy-di-isopropyl) benzene 2,5-di-methyl-2,5-di (benzoylperoxy) hexane, t-butylperoxybenzoate, t-butylperoxy-2-ethyl-hexyl carbonate, and the like. In the present invention, it is preferable to use sulfur as the cross-linking agent, so that the flexibility of the center belt can be improved.

  Vulcanization accelerators may be blended as necessary, and specific examples include guanidine-based, thiuram-based, dithiocarbamic acid-based, thiazole-based, and sulfenamide-based vulcanization accelerators.

  If the blending amount of the carbon black with respect to 100 parts by mass of the hydrogenated nitrile rubber is less than 35 parts by mass, the center belt is not sufficiently reinforced and the wobbling or rattling between the center belt and the block is accelerated. If the blending amount exceeds 70 parts by mass, the hardness becomes high and the bending resistance is rapidly lost, leading to the early cutting of the belt, which is not preferable. Also, by limiting the blending amount of carbon black to a lower range of 35 to 50 parts by mass, it is possible to suppress heat generation during belt running and suppress rubber deterioration, and the problem of block cutting caused by heat Can be reduced.

  In addition, when the blending amount of the short fiber is less than 10 parts by mass with respect to 100 parts by mass of the hydrogenated nitrile rubber, the hardness is also lowered, leading to the occurrence of wobbling and rattling between the center belt and the block. If the amount exceeds 35 parts by mass, the processability of the rubber composition is extremely deteriorated and disadvantageous in terms of bending resistance, and cracking is accelerated, leading to early cutting of the belt, which is not preferable. Further, by limiting the blending amount to a higher range of 25 to 35 parts by mass, the hardness of the rubber can be further increased, and the occurrence of wobbling or wobbling of the block can be suppressed. Furthermore, since the hardness can be secured even if the amount of carbon black is reduced, block wobble and rattling can be suppressed by combining the amount of carbon black limited to 35 to 50 parts by mass. In addition, it is possible to provide a high-load transmission belt having a longer life and less heat generation during belt running.

  In addition, if all short fibers are aramid fibers, the bending resistance of the belt becomes a problem. Therefore, in the present invention, the short fibers to be blended are aramid fibers and nylon fibers to improve the flexibility, and the blending amount of nylon fibers is 5 It is preferably ~ 15 parts by mass. If the blending amount of the nylon fiber is less than 5 parts by mass, the bending resistance is lowered, and cracking occurs due to bending fatigue, leading to failure. Conversely, if the blending amount of nylon exceeds 15 parts by mass, rubber This is not preferable because the processability at the time of non-crosslinking deteriorates and, for example, it becomes difficult to obtain a sheet having a predetermined thickness when the sheet is put out.

  In addition to the above, fillers that improve wear resistance such as carbon black, calcium carbonate, and talc, which are usually blended with rubber, crosslinking aids, crosslinking accelerators, plasticizers, stabilizers, processing aids, anti-aging agents It is possible to add additives such as colorants and colorants depending on the intended use. The method of mixing these compounding agents also includes a method of kneading using a commonly used means such as a Banbury mixer or a kneader.

  As the core 5, a rope selected from polyester fiber, polyamide fiber, aramid fiber, glass fiber, steel wire and the like is used. The core wire 5 may be made of a woven fabric, knitted fabric, metal thin plate, or the like of the above-mentioned fiber other than a rope embedded in a spiral shape.

  The block 2 is made of a synthetic resin material. For example, an insert material having a substantially block shape made of a metal such as an aluminum alloy may be embedded inside, or the insert material may be embedded. It does n’t matter if you do n’t. In addition to the insert material, for example, a reinforcing material such as a short fiber or whisker added in a form mixed in the synthetic resin material may be added.

  The block resin can be either a thermoplastic resin or a thermosetting resin, and the thermoplastic resin is a polyamide resin such as 6,6-nylon, 4,6-nylon, 9, T-nylon. Synthetic resins such as polyamide imide (PAI) resin, polyphenylene sulfide (PPS) resin, polybutylene terephthalate (PBT) resin, polyimide (PI) resin, polyether sulfone (PES) resin, polyether ether ketone (PEEK) resin, etc. Used. On the other hand, as the thermosetting resin, hard rubber having a hardness of 90 ° JIS A or more, hard polyurethane resin, liquid crystal resin, phenol resin, epoxy resin, polyester resin, acrylic resin, methacrylic resin, polyamide resin, polyamideimide (PAI) resin Rubber, such as polyphenylene sulfide (PPS) resin, polybutylene terephthalate (PBT) resin, polyimide (PI) resin, polyether sulfone (PES) resin, polyether ether ketone (PEEK) resin, and synthetic resins are used.

  In the present invention, long fibers are blended in the synthetic resin forming the block as described above, but it is also possible to blend a whisker-like reinforcing material, specifically, zinc oxide whisker and titanium. Inorganic fibers such as potassium acid whisker and aluminum borate whisker may be blended. In these, it is preferable to use a zinc oxide whisker. The zinc oxide whisker has a three-dimensional shape with hands extending in all directions in a tetrapot shape. This zinc oxide whisker alone is excellent in heat resistance and wear resistance, but because it has a tetrapod-like three-dimensional shape as described above, when blended with carbon fiber, the orientation of carbon fiber Is suppressed, and anisotropy of warpage during molding and molding shrinkage is improved. Further, since the orientation of the carbon fibers can be reduced in this way, the anisotropy of strength such as toughness and bending rigidity of the block 2 can be reduced, and the friction coefficient is stabilized, so that the wear resistance is improved. To do.

  Moreover, since the zinc oxide whisker has a high specific gravity and high rigidity, it is possible to reduce vibration during contact with the pulley and to reduce noise generation. In addition, when there are few compounding quantities of this zinc oxide whisker, the added effect does not express, and when too large, it cannot knead | mix and it becomes difficult to shape | mold.

  By adopting such a material structure, it has strength such as rigidity and toughness that can sufficiently withstand the side pressure received when it comes into contact with the pulley, has excellent wear resistance, and further, with respect to heat generated during friction. The power received from the pulley can be efficiently transmitted as a tensile force to the center belts 3a and 3b, and a tension transmission type high load transmission belt can be configured.

In addition to these, the lubricity of the block 2 can be improved by mixing at least one selected from molybdenum disulfide, graphite, and fluorine-based resin. Examples of the fluororesin include polytetrafluoroethylene (PTFE), polyfluorinated ethylene propylene ether (PFPE), tetrafluoroethylene hexafluoropropylene copolymer (PFEP), and polyfluorinated alkoxyethylene (PFA). .
Next, the rubber composition used in the high load transmission belt and the center belt for the high load transmission belt of the present invention, the type of rubber, the amount of carbon black, and the amount of short fibers are out of the scope of the present invention. A comparative test was performed using the prepared test piece.

Example 1
In Example 1, 5 parts by mass of aramid short fibers (manufactured by Cornex Teijin) and 5 parts by mass of nylon short fibers (6,6-nylon Asahi Kasei) and carbon black (N220 Tokai) with respect to 100 parts by mass of H-NBR. 70 parts by mass of carbon) and other antioxidants, softeners, zinc oxide, sulfur, and crosslinking accelerators are blended in the blending amounts shown in Table 1, kneaded, and then molded into a predetermined thickness size for hot pressing. The test sample was crosslinked at a temperature of 153 ° C. for 30 minutes.

  Using the test sample, the hardness was measured, and the number of flexing until the crack reached 10 mm was measured by the Dematcher flexing test. Further, a belt having a belt pitch width of 18 mm, a pitch circumferential length of 600 mm, and a block pitch of 3 mm was manufactured, and a running test was performed to check the presence or absence of block wobbling after 50 hours. Was measured.

(Example 2)
Example 2 is the same as Example 1 except that the blending amount of aramid short fibers (manufactured by Conex Teijin) was 15 parts by mass, the blending amount of nylon short fibers was 10 parts by mass, and the blending amount of carbon blocks was 60 parts by mass. The test samples were prepared by blending, kneading and crosslinking in the same manner.

  Using the test sample, the hardness was measured, and the number of flexing until the crack reached 10 mm was measured by the Dematcher flexing test. Further, a belt having a belt pitch width of 18 mm, a pitch circumferential length of 600 mm, and a block pitch of 3 mm was manufactured, and a running test was performed at an atmospheric temperature of 80 ° C. For, the time until belt breakage was measured.

(Example 3)
Example 3 is the same as Example 1 except that the blending amount of aramid short fibers (manufactured by Conex Teijin) is 15 parts by mass, the blending amount of nylon short fibers is 15 parts by mass, and the blending amount of carbon black is 50 parts by mass. The test samples were prepared by blending, kneading and crosslinking in the same manner.

  Using the test sample, the hardness was measured, and the number of flexing until the crack reached 10 mm was measured by the Dematcher flexing test. Furthermore, a belt having a belt pitch width of 18 mm, a pitch circumference of 600 mm, and a block pitch of 3 mm was prepared and manufactured, and a running test was performed at an atmospheric temperature of 80 ° C. For the sample, the time until belt breakage was measured.

Example 4
Example 4 was blended in the same manner as in Example 1 except that the blending amount of aramid short fibers (manufactured by Conex Teijin) was 15 parts by mass, the blending amount of carbon black was 10 parts by mass of nylon short fibers, and 40 parts by mass. A test sample was prepared by kneading and crosslinking.

  Using the test sample, the hardness was measured, and the number of flexing until the crack reached 10 mm was measured by the Dematcher flexing test. Furthermore, a belt having a belt pitch width of 18 mm, a pitch circumference of 600 mm, and a block pitch of 3 mm was prepared and manufactured, and a running test was performed at an atmospheric temperature of 80 ° C. For the sample, the time until belt breakage was measured.

(Example 5)
In Example 5, the blending amount of aramid short fibers (manufactured by Conex Teijin) is 15 parts by mass, the blending amount of nylon short fibers is 10 parts by mass, the blending amount of the carbon block is 60 parts by mass, and not sulfur as a crosslinking agent. A test sample was prepared by blending in the same manner as in Example 1 except that the organic peroxide was blended, and kneading and crosslinking.

  Using the test sample, the hardness was measured, and the number of flexing until the crack reached 10 mm was measured by the Dematcher flexing test. Further, a belt having a belt pitch width of 18 mm, a pitch circumferential length of 600 mm, and a block pitch of 3 mm was prepared and manufactured, and a running test was performed at an atmospheric temperature of 80 ° C. to confirm whether or not the block wobbled after 50 hours of running and there was no wobble. For the sample, the time until belt breakage was measured.

(Comparative Example 1)
Comparative Example 1 is an example except that the blending amount of aramid short fibers (Conex Teijin) was 15 parts by mass, the blending amount of carbon black was 10 parts by mass of nylon short fibers, and 30 parts by mass outside the scope of the present invention. A test sample was prepared by blending in the same manner as in No. 1, kneading and crosslinking.

  Using the test sample, the hardness was measured, and the number of flexing until the crack reached 10 mm was measured by the Dematcher flexing test. Furthermore, a belt having a belt pitch width of 18 mm, a pitch circumference of 600 mm, and a block pitch of 3 mm was prepared and manufactured, and a running test was performed at an atmospheric temperature of 80 ° C. For the sample, the time until belt breakage was measured.

(Comparative Example 2)
Comparative Example 2 is an example except that the blending amount of aramid short fibers (manufactured by Conex Teijin) was 15 parts by mass, the blending amount of carbon black was 10 parts by mass of nylon short fibers, and 80 parts by mass outside the scope of the present invention. A test sample was prepared by blending in the same manner as in No. 1, kneading and crosslinking.

  Using the test sample, the hardness was measured, and the number of flexing until the crack reached 10 mm was measured by the Dematcher flexing test. Further, a belt having a belt pitch width of 18 mm, a pitch circumferential length of 600 mm, and a block pitch of 3 mm was prepared and manufactured, and a running test was performed at an atmospheric temperature of 80 ° C. to confirm whether or not the block wobbled after 50 hours of running and there was no wobble. For the sample, the time until belt breakage was measured.

(Comparative Example 3)
In Comparative Example 3, the blending amount of aramid short fibers (Conex Teijin) is 3 parts by mass, the blending amount of nylon fibers is 3 parts by mass, and the total blending amount of short fibers is 6 parts by mass outside the scope of the present invention. A test sample was prepared by mixing, kneading, and crosslinking in the same manner as in Example 1 except that the amount of carbon black was 60 parts by mass.

  Using the test sample, the hardness was measured, and the number of flexing until the crack reached 10 mm was measured by the Dematcher flexing test. Furthermore, a belt having a belt pitch width of 18 mm, a pitch circumference of 600 mm, and a block pitch of 3 mm was prepared and manufactured, and a running test was performed at an atmospheric temperature of 80 ° C. For the sample, the time until belt breakage was measured.

(Comparative Example 4)
Comparative Example 4 is 30 parts by mass of the aramid short fibers (Conex Teijin), 10 parts by mass of the nylon fibers and 40 parts by mass of the total amount of the short fibers, A test sample was prepared by mixing, kneading, and crosslinking in the same manner as in Example 1 except that the amount of carbon black was 60 parts by mass.

  Using the test sample, the hardness was measured, and the number of flexing until the crack reached 10 mm was measured by the Dematcher flexing test. Furthermore, a belt having a belt pitch width of 18 mm, a pitch circumference of 600 mm, and a block pitch of 3 mm was prepared and manufactured, and a running test was performed at an atmospheric temperature of 80 ° C. For the sample, the time until belt breakage was measured.

(Comparative Example 5)
Comparative Example 5 was formulated in the same manner as in Example 1 except that the blending amount of aramid short fibers (Conex Teijin) was 25 parts by mass, the nylon fiber was not blended, and the blending amount of carbon black was 60 parts by mass. A test sample was prepared by kneading and crosslinking.

  Using the test sample, the hardness was measured, and the number of flexing until the crack reached 10 mm was measured by the Dematcher flexing test. Further, a belt having a belt pitch width of 18 mm, a pitch circumferential length of 600 mm, and a block pitch of 3 mm was prepared and manufactured, and a running test was performed at an atmospheric temperature of 80 ° C. to confirm whether or not the block wobbled after 50 hours of running and there was no wobble. For the sample, the time until belt breakage was measured.

(Comparative Example 6)
Comparative Example 6 uses 10 parts by mass of the aramid short fibers (Conex Teijin), 20 parts by mass of the nylon fibers, and the amount of the nylon short fibers falls outside the scope of the present invention. A test sample was prepared by mixing, kneading, and crosslinking in the same manner as in Example 1 except that the blending amount was 60 parts by mass.

  Using the test sample, the hardness was measured, and the number of flexing until the crack reached 10 mm was measured by the Dematcher flexing test. Furthermore, a belt having a belt pitch width of 18 mm, a pitch circumference of 600 mm, and a block pitch of 3 mm was prepared and manufactured, and a running test was performed at an atmospheric temperature of 80 ° C. For the sample, the time until belt breakage was measured.

  The formulations of Examples 1 to 4 and Comparative Examples 1 to 6 are shown in Table 2, the test conditions of the running test are shown in Table 2, and the test results are shown in Table 3.

  As can be seen from the results in Table 3, Examples 1 to 5 have good results in the bending test while maintaining a certain degree of hardness. In the belt running test, block wobbling does not occur and the time until the belt breaks is longer than the comparative example. Among them, it can be seen that Example 4 is a belt that has a longer time to break due to bending and a longer life.

  On the other hand, in Comparative Example 1 with a small amount of carbon black, the hardness is low and the amount of short fibers is large, so the flexibility is excellent, but the block wobble occurs in 50 hours of running in the belt running test. It has been interrupted. On the contrary, Comparative Example 2 has a poor bending test result due to the large amount of carbon black. In Comparative Example 3, the amount of short fibers is reduced, but the hardness is low and block wobbling occurs. In Comparative Example 4, the total amount of short fibers is large, and as a result, the flexibility is poor. In Comparative Example 5, since the short fibers are only aramid fibers, the flexibility is somewhat inferior. Comparative Example 6 is an example in which the blending amount of nylon short fibers was increased, but the belt could not be produced because the processability was poor and the sheet could not be taken out.

  Also, in Examples 1 to 5, the results of the bending test are better in Examples 1 to 4 than in Example 5 in which peroxide is used as a crosslinking agent. Have been confirmed to have an effect.

  The present invention can be applied to the manufacture of belts that change the effective diameter of pulleys and transmit large torque, such as continuously variable transmissions for automobiles, motorcycles, and agricultural machines.

It is a perspective schematic diagram showing an example of the high load transmission belt concerning the present invention. It is a perspective schematic diagram showing other examples of the high load power transmission belt concerning the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 High load power transmission belt 2 Block 3a Center belt 3b Center belt 4 Elastomer 5 Core wire 11 Upper beam part 12 Lower beam part 13 Center pillar 14 Fitting groove 15 Fitting groove

Claims (8)

  In a high-load transmission belt in which a center belt and a plurality of blocks are fitted and fixed at a predetermined pitch along the longitudinal direction of the center belt, the rubber composition constituting the center belt is shorter than 100 parts by mass of hydrogenated nitrile rubber. 10 to 35 parts by mass of fiber and 35 to 70 parts by mass of carbon black are blended, and the short fiber is composed of aramid short fiber and nylon short fiber, and the blending amount of nylon short fiber is 5 to 15 parts by mass. High load transmission belt.   The high-load transmission belt according to claim 1, wherein the blending amount of the short fibers is 25 to 35 parts by mass with respect to 100 parts by mass of the hydrogenated nitrile rubber.   The high load transmission belt according to claim 2, wherein the compounding amount of carbon black is 35 to 50 parts by mass with respect to 100 parts by mass of the hydrogenated nitrile rubber.   The high-load transmission belt according to claim 1, wherein the center belt has a sulfur-based crosslink.   In a center belt used for a center belt and a high load transmission belt in which a plurality of blocks are fitted and fixed at a predetermined pitch along the longitudinal direction of the center belt, the rubber composition constituting the center belt is 100 parts by mass of hydrogenated nitrile rubber. 10 to 35 parts by mass of short fibers and 35 to 70 parts by mass of carbon black, and the short fibers are composed of aramid short fibers and nylon short fibers, and the amount of nylon short fibers is 5 to 15 parts by mass. A center belt for high load transmission belts, characterized by being.   The center belt for a high load transmission belt according to claim 5, wherein the blend amount of the short fiber is 25 to 35 parts by mass with respect to 100 parts by mass of the hydrogenated nitrile rubber.   The center belt for a high load transmission belt according to claim 6, wherein the compounding amount of carbon black is 35 to 50 parts by mass with respect to 100 parts by mass of the hydrogenated nitrile rubber. The center belt for a high load transmission belt according to claim 5, wherein the rubber of the center belt is sulfur-based.

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