JP2009052740A - V-belt - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a transmission belt capable of improving resistance to tearing-down and having excellent durability, heat resistance, cold resistance, and wear resistance. <P>SOLUTION: The V-belt 1 has a configuration constituted by laminating a compressed rubber layer 2 on an inner peripheral side, an extended rubber layer 5 on an outer peripheral side, and a bonded rubber layer 8 between both rubber layers 2 and 5, and a core wire 9 extended in the longitudinal direction of the belt is buried in the bonded rubber layer 8. Cogged crests 3, 6 and cogged troughs 4, 7 extended in the direction of belt width are formed in the compressed rubber layer 2 and the extended rubber layer 5. Here, the compressed rubber layer 2 is constituted by an organic peroxide bridge forming substance of a rubber component formed by blending short fibers of 5 to 50 pts.wt. containing PBO short fibers of 5 to 40 pts.wt. into ethylene-α-olefin rubber of 100 pts.wt. containing ethylene of 40 to 70 wt.%, and its hardness is set within 85-93 JIS A. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention mainly relates to a V-belt used for power transmission of a transmission such as a CVT.

  In recent years, the environmental temperature of transmission belts used in CVTs has increased as the displacement of motorcycles has increased. Conventionally, natural rubber, styrene-butadiene rubber, chloroprene rubber, and the like have been mainly used for power transmission belts, but there was a problem that cracks occurred early in the cured compressed rubber layer under a high temperature atmosphere. . Further, since rubber containing halogen such as chloroprene leads to generation of dioxins, a belt made of rubber not containing halogen which is an environmental load substance has been demanded in recent years.

  Recently, ethylene / α-olefin rubber such as ethylene / propylene rubber (EPM) or ethylene / propylene / diene copolymer (EPDM) has excellent ozone resistance, heat resistance and cold resistance. It is a promising material because it is a relatively inexpensive polymer and satisfies the requirement of dehalogenation.

  For example, in Patent Document 1, a rubber composition obtained by crosslinking a rubber composition in which polyparaphenylene benzobisoxazole short fibers and methacrylic acid ester or acrylic acid ester are blended with ethylene / α-olefin rubber with an organic oxide is transmitted. It is disclosed for use in a belt.

  Patent Document 2 discloses a power transmission using a rubber composition in which a maleimide vulcanizing agent is used as a co-crosslinking agent for ethylene / α-olefin rubber and a polyparaphenylene benzobisoxazole short fiber is blended. A belt is disclosed.

JP 2007-9966 A JP 2005-147392 A

  However, ethylene / α-olefin rubber has a poor tearing force, and when an organic peroxide crosslinking system is used, the tearing force is further reduced. On the other hand, those using a sulfur cross-linking system have a problem that wear during running increases because it is difficult to sufficiently increase the degree of vulcanization. In addition, when EPDM having an extremely large amount of double bonds in the molecule was used to increase the degree of vulcanization, adhesive wear could be improved to some extent, but a problem that heat resistance was reduced occurred.

  In addition, polyparaphenylene benzobisoxazole (PBO) short fibers have poor adhesion to ethylene / α-olefin rubber, and by combining them, physical properties such as wear resistance are improved, but if the rubber hardness is too low, There is a problem that the wearability is deteriorated, and conversely, the hardness becomes too high and cracks are caused by the PBO short fibers having particularly poor adhesion.

  The present invention solves such problems, and has an object to provide a V-belt that improves tear resistance, has high durability, heat resistance, and cold resistance, and is excellent in wear resistance. To do.

  In the invention according to claim 1 of the present invention, in a V-belt having a compression rubber layer and an extension rubber layer and having a core wire embedded along the belt longitudinal direction, the compression rubber layer has an ethylene content of 40 to 70% by mass. Organic peroxide cross-linking of a rubber composition in which 5 to 50 parts by mass of short fibers containing 5 to 40 parts by mass of polyparaphenylenebenzobisoxazole short fibers are added to 100 parts by mass of ethylene / α-olefin rubber The compression rubber layer is characterized in that the elongation at break in the longitudinal direction of the belt is 70% or more.

  According to a second aspect of the present invention, the V-belt according to the first aspect of the present invention is such that the compression rubber layer has a longitudinal elongation at break of 200% or more.

  In Claim 3, it is set as the V belt in any one of Claims 1-2 which set the hardness of the compression rubber layer in the range of 85-93JIS-A.

  In Claim 4, the short fiber is the V-belt according to any one of claims 1 to 3 including an aramid short fiber.

  In Claim 5, it is set as V belt of Claims 1-4 formed by mix | blending 0.5-10 mass parts of N, N'-m-phenylene dimaleimide with respect to 100 mass parts of ethylene and alpha-olefin rubber. .

  In claim 1 of the present invention, the compression rubber layer, which is a part of the V-belt, is made of a specific rubber composition, thereby improving tear resistance and providing high durability, heat resistance and cold resistance. A V-belt having excellent wear resistance can be obtained.

  In claim 2, it is specified that the breaking elongation in the longitudinal direction of the belt of the compressed rubber layer is a numerical value greater than or equal to a predetermined value, and it is possible to prevent cracks from occurring in the compressed rubber layer. Obtainable.

  Moreover, although it becomes easy to generate | occur | produce a crack in a rubber layer by mix | blending a polyparaphenylene benzobisoxazole (PBO) short fiber, in Claim 3, by setting the hardness of a compression rubber layer to 85 JIS-A or more, Even if it receives a large lateral pressure from the pulley, it is not greatly deformed, generation of wear can be suppressed, and the effect of improving the wear resistance by blending the PBO fiber can be fully enjoyed.

  Further, in claim 4, when aramid short fibers are used in combination, it is possible to reduce the amount of polyparaphenylene benzobisoxazole short fibers blended at a high cost while maintaining a high level of wear resistance. An excellent and high modulus structure can be obtained.

  In claim 5, maleimide is used as a co-crosslinking agent, and it can have high modulus and excellent heat resistance and tear resistance.

The present invention will be described below with reference to the drawings.
A cogged V-belt 1 used as a transmission belt as an example of the V-belt according to the present invention is shown in FIG.

  The cogged V-belt 1 has a configuration in which an inner peripheral compression rubber layer 2, an outer peripheral extension rubber layer 5, and an adhesive rubber layer 8 are laminated between the rubber layers 2, 5. A core wire 9 extending in the longitudinal direction of the belt is embedded therein. The compressed rubber layer 2 and the stretched rubber layer 5 are alternately formed with cog mountains 3 and 6 and cog valleys 4 and 7 extending in the belt width direction.

  The compressed rubber layer 2, the stretch rubber layer 5, and the adhesive rubber layer 8 are made of a rubber composition. In the present invention, at least a part of the main body is a short containing 5 to 40 parts by weight of polyparaphenylene benzobisoxazole short fiber with respect to 100 parts by weight of ethylene / α-olefin rubber having an ethylene content of 40 to 70% by weight. It is characterized by comprising an organic peroxide-based crosslinked product of a rubber composition containing 5 to 50 parts by weight of fibers. Taking the cogged V-belt 1 as an example, any one layer, two layers, or all three layers of the compression rubber layer 2, the stretch rubber layer 5 and the adhesive rubber layer 8 are organic peroxide-based crosslinked of the rubber composition. Although it can be comprised with a thing, it is desirable for the compressed rubber layer 2 to have the said structure at least.

  The compressed rubber layer 2 preferably has a breaking elongation in the longitudinal direction of the belt of 70 or more, more preferably 200% or more. By having such physical properties, the belt is less likely to crack and has a longer life. It can be a belt.

  Examples of ethylene / α-olefin rubbers include copolymers of ethylene and α-olefins (propylene, butene, hexene, octene, etc.) or copolymers of ethylene, the above α-olefins, and non-conjugated dienes. Specifically, it refers to rubbers such as ethylene / propylene rubber (EPM) and ethylene / propylene / diene copolymer (EPDM). Examples of the diene component include non-conjugated dienes having 5 to 15 carbon atoms such as ethylidene norbornene, dicyclopentadiene, 1,4-hexadiene, cyclooctadiene, and methylene norbornene.

  The ethylene / α-olefin rubber used in the present invention has an ethylene content of 40 to 70% by weight. If it is less than 40% by weight, the wear during belt running becomes severe, and if it exceeds 70% by weight, the sheeting property of the rubber sheet is lowered and the belt molded body may be cracked at the beginning of running. In addition, when an ethylene / α-olefin rubber having a Mooney viscosity (JIS K6300-1) at 125 ° C. of 20 to 75 is used, poor cog formation can be suppressed, and as a result, a cog belt having a good cog shape can be obtained. it can.

  The rubber composition contains an organic peroxide as a crosslinking agent. Examples of the organic peroxide include dicumyl peroxide, di-t-butyl peroxide, t-butylcumyl peroxide, benzoyl peroxide, 1,3-bis (t-butylperoxyisopropyl) benzene, 2,5 -Dimethyl-2,5-di (t-butylperoxy) hexyne-3,2,5-dimethyl-2,5- (benzoylperoxy) hexane, 2,5-dimethyl-2,5-mono (t- Butyl peroxy) hexane and the like. This organic peroxide is preferably used alone or as a mixture in the range of 0.5 to 8 parts by weight with respect to 100 parts by weight of rubber.

  Moreover, the thing which the hardness of the thing which bridge | crosslinked this rubber composition is the range of 85-93JIS-A is used. By setting the hardness to 85 JIS-A or higher, the wear resistance of the belt can be greatly improved in combination with the blending of PBO short fibers, and the life of the belt can be extended. On the other hand, when the hardness exceeds 93 JIS-A, it becomes too hard, and cracks are likely to occur due to repeated bending of the belt, which is not preferable.

  And it is preferable that the said rubber composition mix | blends a maleimide type crosslinking agent in 0.1-10 mass parts with respect to 100 mass parts of ethylene * alpha-olefin rubber. By blending a certain amount of maleimide-based crosslinking agent, physical properties such as heat resistance, cold resistance and tear resistance can be improved. For example, it should have a sufficient lifetime even when used in a severe temperature environment such as in an engine room. Can do. As the maleimide-based crosslinking agent, N, N′-m-phenylene dimaleimide can be exemplified.

  Furthermore, 0.1-10 weight part of methacrylic acid ester and / or acrylic acid ester may be mix | blended with the said rubber composition with respect to 100 weight part of ethylene * alpha-olefin rubber. Methacrylic acid ester and / or acrylic acid ester acts as a co-crosslinking agent in organic peroxide crosslinking, and if less than 0.1 part by weight, the effect by addition is not remarkable, and if it exceeds 10 parts by weight, tearing force and adhesive strength Decreases rapidly.

  Specific examples of the methacrylic acid ester and / or acrylic acid ester include ethylene dimethacrylate, polyethylene glycol dimethacrylate, propylene glycol dimethacrylate, dipropylene glycol dimethacrylate, tripropylene glycol dimethacrylate, trimethylolpropane trimethacrylate, pentaerythritol tetra Examples thereof include methacrylates and acrylates corresponding to these. These can be used alone or in admixture of two or more. Of these, trimethylolpropane trimethacrylate (TMPT) is preferable.

  The rubber composition contains 5 to 50 parts by weight of short fibers containing 5 to 40 parts by weight of polyparaphenylene benzobisoxazole short fibers (PBO short fibers) with respect to 100 parts by weight of the ethylene / α-olefin rubber. It is blended. In the present invention, PBO short fibers having a fiber length of 1 to 20 mm and a fiber diameter of 1 to 3 denier are preferably used.

  Moreover, it is not essential to add the PBO short fibers alone, and it is also possible to add short fibers made of other materials. Examples of short fibers that can be blended in addition to PBO short fibers include short fibers such as aramid fibers, polyamide fibers, polyester fibers, and cotton. The fiber length varies depending on the fiber type, but a short fiber of 1 to 10 mm is suitable. Specifically, an aramid fiber having a length of 3 to 5 mm, a polyamide fiber, a polyester fiber or cotton having a length of 5 to 10 mm can be used. . Among these, it is preferable to select an aramid fiber in consideration of wear resistance, reinforcement, and the like. Aramid short fibers are, for example, trade names Conex, Nomex, Kevlar, Technora, Twaron and the like. When the aramid short fibers are blended, the PBO fibers and the aramid fibers are preferably blended at a ratio such that the aramid fibers are 200 parts by weight or less with respect to 100 parts by weight of the PBO fibers. It is also possible to control the friction coefficient by the blend ratio of both.

  In addition, since it is difficult to adhere | attach PBO fiber with rubber | gum compared with another fiber, it is desirable to give an adhesion | attachment process. As the adhesion treatment, a known treatment method can be applied. For example, there is a method of treating with a resorcin / formaldehyde / latex (RFL) solution after treatment with an adhesion treatment solution containing a nitrile rubber-modified epoxy resin and an alkylphenol / formaldehyde resin. The aramid short fibers are also preferably subjected to adhesion treatment by a known method using an RFL solution or the like.

  The RFL liquid used here is a treatment liquid in which a resorcin / formaldehyde initial condensate and a rubber latex are mixed. In this case, the molar ratio of resorcin to formaldehyde is preferably 3/1 to 1/3 in order to increase the adhesive force. Moreover, it is preferable when the solid content adhesion amount of RFL liquid is 3-10 weight%, when raising the effect of the adhesive force by RFL liquid. If it exceeds 1/1, the cohesive force of the short fibers becomes large and the dispersibility becomes worse. Conversely, if it becomes less than 1/5, the adhesive strength between the rubber and the short fibers may decrease, and the tensile strength may also decrease. is there. Further, when the solid content adhesion amount of the RFL liquid exceeds 10% by weight, the treatment liquid is hardened and it becomes difficult to split filaments of short fibers. Conversely, when the amount is less than 3% by weight, the dispersibility and tension by the RFL liquid are reduced. Strength improvement effect is not remarkable. Examples of rubber latex include styrene / butadiene / vinylpyridine terpolymer, chlorosulfonated polyethylene, hydrogenated nitrile rubber, epichlorohydrin, natural rubber, SBR, chloroprene rubber, olefin-vinyl ester copolymer, EPDM, and the like. Latex. In addition, the temperature of the process liquid at the time of performing an adhesion process is adjusted to 5 to 40 ° C., and the immersion time is 0.5 to 30 seconds, and it is passed through an oven adjusted to 200 to 250 ° C. for 1 to 3 minutes. It is desirable to be heat treated. In addition, a pre-dip process can be performed before the RFL process, or an overcoat process can be performed after the RFL process.

  The rubber composition may include conventional rubbers such as carbon black and silica, reinforcing agents such as silica, fillers such as calcium carbonate and talc, plasticizers, stabilizers, processing aids, and coloring agents. What is used for blending can be blended. Carbon black is preferably blended in an amount of 20 to 70 parts by weight with respect to 100 parts by weight of rubber.

  The compressed rubber layer 2 and the stretched rubber layer 5 preferably contain fibers, but the adhesive rubber layer 8 preferably contains no fibers in view of adhesiveness to the core wire.

  As the core 9, a twisted cord selected from an aramid fiber, a polyester fiber, a glass fiber or the like and treated with an RFL liquid or the like can be used.

  If necessary, a reinforcing cloth can be laminated on the surface of the compressed rubber layer 2 or the surface of the stretched rubber layer 5. Examples of the reinforcing fabric include canvas selected from woven fabrics, knitted fabrics, nonwoven fabrics, and the like. Known and publicly used fiber materials can be used. For example, natural fibers such as cotton and hemp, inorganic fibers such as metal fibers and glass fibers, and polyamide, polyester, polyethylene, polyurethane, polystyrene, and polyfluoroethylene. , Organic fibers such as polyacryl, polyvinyl alcohol, wholly aromatic polyester, and aramid. The canvas can be immersed in an RFL solution and then rubbed with an unvulcanized rubber after immersion in a known technique, or can be immersed in a soaking solution in which the rubber is dissolved in a solvent after being immersed in the RFL solution. The RFL solution may be appropriately mixed with a carbon black solution to blacken the treatment, or a known surfactant may be added in an amount of 0.1 to 5.0% by weight.

  As a method for preparing the rubber composition used in the present invention, first, as a masterbatch kneading in the first step, short fibers and a softening agent are added to an ethylene / α-olefin rubber in a closed kneader such as a Banbury mixer. After kneading, the kneaded master batch is discharged once and cooled to 20-50 ° C. This is to prevent rubber scorching. Next, a predetermined amount of reinforcing agent, filler, anti-aging agent, vulcanization accelerator, vulcanizing agent and the like are finished and kneaded into the obtained master batch using a Banbury mixer and an open roll. Further, depending on the type of rubber, it is not necessary to once discharge the kneaded master batch and cool it down, and it is possible to carry out finish kneading continuously.

  The kneading method is not limited to the above method, and the kneading means is not limited to, for example, a Banbury mixer, a roll, a kneader, or an extruder, and may be appropriately kneaded by known means and methods. it can. Further, the vulcanization method is not limited, and vulcanization is performed by a known means using a vulcanization apparatus such as mold heating, hot air heating, a rotating drum vulcanizer, an injection molding machine or the like.

  By constituting the compressed rubber layer 2 with the organic peroxide-based crosslinked product of the rubber composition to which the compounding agent has been added as described above, the tear resistance and the side pressure resistance are improved, and a long life with a wear resistance effect is achieved. A transmission belt can be provided. Furthermore, it exhibits good durability even at low temperatures.

  Note that the CVT (continuously variable transmission) V-belt is not limited to the above-described configuration, and examples thereof include a cogged V-belt in which a cog is provided only on one of the compression rubber layer and the stretch rubber layer. .

Hereinafter, a description will be given with specific examples.
The Mooney viscosity (125 ° C.) of the rubber composition prepared by blending shown in Table 1 was measured according to JIS K6300-1. In addition, the PBO short fiber used what gave the adhesion process. Further, the rubber composition was vulcanized at 165 ° C. for 30 minutes, and the hardness (JIS-A) of the obtained vulcanized rubber (organized oxide-based crosslinked product) was JIS K6253, and tear strength (JIS-A: N). / Mm) was measured according to JIS K6252. In addition, the breaking elongation of the compressed rubber layer was cut out from a belt with five rubber strips having a thickness of 1 mm, a width of 5 mm, and a length of 100 mm in the longitudinal direction, with a 20 mm mark at the center, and a speed of 500 ± 50 m / min. The average value was recorded by pulling. Table 2 shows the measurement results.

  A cut edge type cogged V-belt was prepared using the rubber composition. The cogged V-belt produced in this example has a compression rubber layer in which one ply canvas is laminated on the surface, a stretch rubber layer in which one ply canvas is laminated on the surface, and a cord made of polyester fiber rope between both rubber layers. It has a configuration in which an adhesive rubber layer in which is embedded is disposed. Cogs are formed on the inner and outer peripheral surfaces of the belt. The compressed rubber layer and the stretched rubber layer contain short fibers and are oriented in the belt width direction.

  Here, the rubber sheet forming the stretched rubber layer and the compressed rubber layer was prepared with the rubber composition shown in Table 1, kneaded with a Banbury mixer, and then rolled with a calendar roll. The rubber sheet forming the adhesive rubber layer was prepared by adjusting the rubber composition shown in Table 1 with a rubber composition excluding short fibers, kneaded with a Banbury mixer, and then rolled with a calender roll.

  The belt manufacturing method is a known method. First, a one-ply reinforcing cloth, an unvulcanized compressed rubber sheet, and an unvulcanized adhesive rubber sheet are wound around the circumferential surface of a cylindrical drum provided with grooves at predetermined intervals. After that, a core rope was spun into a spiral shape, and an unvulcanized stretched rubber sheet and a 1-ply reinforcing cloth were wound to obtain a laminate (unvulcanized belt sleeve). Sulfurize to obtain a vulcanized belt sleeve. The vulcanized belt sleeve thus obtained was cut into a predetermined width by a cutter and finished into individual cogged V-belts.

  The durability of the cogged V belt thus obtained was evaluated. In the belt endurance test, the belt is suspended on a biaxial horizontal running tester having the layout shown in FIG. 2, and the driven pulley is loaded with a load of 6.77 kw under an ambient temperature of 85 ° C. The running life of the belt was measured by rotating at 000 rpm. The cut-off time was 240 hours, and when it reached the end of its life, the cause of the failure was confirmed.

  As a result, the belts of the examples were high in cold resistance and heat resistance, improved in tear resistance, excellent in wear resistance and side pressure resistance, and were able to be a long running life. Comparative Example 1 is a belt using chloroprene rubber, and the belts of Examples 1 to 6 are made of ethylene / α-olefin rubber not containing chlorine and have a durability equivalent to that of Comparative Example 1. did it. In Example 7, since the blending amount of short fibers is small and the blending amount of ISAF carbon is small and the hardness is low, the lifetime is lower than that of the other examples. In Example 8, the elongation at break of the compressed rubber layer is small, and cracks are generated in a shorter time compared to other examples.

  Comparative Example 2 is an example in which the blending amount of the PBO short fibers exceeded a predetermined range, and as a result, poor dispersion occurred and cracks occurred, resulting in failure in a short period of time. In Comparative Example 3, no PBO fiber was blended, so that the wear resistance was inferior, resulting in a failure due to large wear. In Comparative Example 4, the maleimide crosslinking agent was added in a large amount and the hardness exceeded 93 JIS-A, and the fracture elongation of the compressed rubber layer was low.

  Thus, the rubber in the range of 85 to 93 JIS A, in which polyparaphenylene benzobisoxazole (PBO) short fibers are blended with ethylene / α-olefin rubber within a predetermined range and crosslinked with an organic oxide. By using a V-belt having at least a compressed rubber layer made of the composition, it is possible to efficiently impart the effect of improving the wear resistance by blending PBO short fibers without increasing the occurrence of cracks. Furthermore, by including aramid fibers in a predetermined ratio as short fibers, the cost of the belt can be reduced without impairing the effect of wear resistance, and by adding N, N′-m-phenylene dimaleimide, the modulus can be reduced. As well as improving heat resistance and cold resistance, the belt can have a longer life.

  The transmission belt according to the present invention can be attached to a drive device for automobiles or general industries.

It is a section perspective view of the V belt which is a power transmission belt concerning the present invention. It is a figure which shows the layout of the testing machine used in the belt durability test.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Cogged V belt 2 Compression rubber layer 3,6 Cog mountain 4,7 Cog valley 5 Stretch rubber layer 8 Adhesive rubber layer 9 Core wire

Claims (5)

  In a V-belt having a compression rubber layer and an extension rubber layer and having a core wire embedded along the longitudinal direction of the belt, the compression rubber layer is composed of 100 parts by mass of ethylene / α-olefin rubber having an ethylene content of 40 to 70% by mass. On the other hand, it is composed of an organic peroxide-based crosslinked product of a rubber composition in which 5 to 50 parts by mass of short fibers containing 5 to 40 parts by mass of polyparaphenylenebenzobisoxazole short fibers are blended, and the belt length of the compressed rubber layer A V-belt characterized by having a direction breaking elongation of 70% or more.   The V-belt according to claim 1, wherein the compression rubber layer has a breaking elongation in the longitudinal direction of the belt of 200% or more.   The V-belt according to any one of claims 1 and 2, wherein the hardness of the compressed rubber layer is set in a range of 85 to 93 JIS-A.   The V-belt according to claim 1, wherein the short fibers include aramid short fibers.   The V belt according to claim 1, wherein 0.5 to 10 parts by mass of a maleimide crosslinking agent is blended with 100 parts by mass of ethylene / α-olefin rubber.

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