JP2006153027A - Rubber composition for belt and v ribbed belt - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a rubber composition having, in particular, excellent tear strength and to provide a V ribbed belt using it. <P>SOLUTION: This rubber composition for a belt is constituted by mixing 45 to 50 mass parts of carbon black, 20 to 40 mass parts of short fibers, and 5 to 10 mass parts of softener or plasticizer into 100 mass parts of rubber. This V ribbed belt 1 is constituted by using the rubber composition. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a rubber composition for a belt and a V-ribbed belt, and more particularly to a rubber composition having improved rubber tear resistance by reducing the hardness of the rubber composition and a V-ribbed belt using the same.

  In recent years, there has been a demand for improved mechanical fatigue resistance in rubber products that are subjected to advanced mechanical stimuli. For example, in automotive transmission belts, narrowing, quietness, and long service life have been achieved with higher engine output. In order to realize these, it is essential to improve the performance and life of the material of the transmission belt.

  Conventionally, high-performance belt materials include, for example, tensile obtained by mixing hydrogenated rubber made of an ethylenically unsaturated nitrile-conjugated diene copolymer with zinc methacrylate and an organic peroxide. Rubber composition with improved strength (Patent Document 1), rubber composition comprising an esterified product of a solid rubber and a liquid diene polymer having a hydroxyl group at the terminal and alkenyl succinic anhydride, and exhibiting excellent tensile strength (Patent Document 2) and the like are known.

Japanese Unexamined Patent Publication No. 1-311158 Japanese Examined Patent Publication No. 4-55453

  In addition, as a belt material with a long service life, when a general rubber composition is crosslinked with an organic peroxide, a sulfur component is allowed to act as a co-crosslinking agent, so that bending fatigue characteristics and tear strength are increased. Has been proposed (Patent Document 3). Furthermore, as a belt having a long life, a belt rubber member in which short fibers of fluororesin are added is known (Patent Document 4).

Japanese Patent No. 2637876 Japanese Patent Publication No. 4-55453

  However, although the rubbers made of the conventional rubber composition are all excellent in tensile strength, the physical properties such as bending fatigue and tear strength are not always satisfactory. There is a problem that it is difficult to use for a product that receives a high degree of mechanical stimulation as the engine output increases.

  The present invention has been made in view of the prior art, and an object of the present invention is to provide a rubber composition exhibiting particularly excellent tear strength and a V-ribbed belt using the same.

  The present invention resides in a rubber composition for a belt in which 45 to 50 parts by mass of carbon black, 20 to 40 parts by mass of short fibers, and 5 to 10 parts by mass of a softener or plasticizer are mixed with 100 parts by mass of rubber.

  According to a second aspect of the present invention, the hardness after vulcanization of the rubber composition is 75 to 82 degrees when measured with a type A hardness meter of a spring type hardness test of JISK6301. The rubber composition for belts.

  The invention according to claim 3 is the rubber composition for belt according to claim 1 or 2, wherein the softening agent or plasticizer is at least one of paraffinic oil or naphthene.

  The invention according to claim 4 is the rubber composition for a belt according to any one of claims 1 to 3, wherein the tearing force is 50 to 70 N / mm.

  According to a fifth aspect of the present invention, there is provided a V-ribbed belt comprising: an adhesive rubber layer having a core wire embedded along the belt length direction; and a compressed rubber layer having at least two rib portions extending in the belt length direction. The compressed rubber is in a V-ribbed belt made of the rubber composition according to any one of claims 1 to 4.

  The invention according to claim 6 is the V-ribbed belt according to claim 5, wherein the core wire diameter is 1.0 to 1.2 mm.

  According to the present invention, it is a rubber composition for belts in which 45 to 50 parts by mass of carbon black, 20 to 40 parts by mass of short fibers, and 5 to 10 parts by mass of a softener or plasticizer are mixed with 100 parts by mass of rubber. Thus, the hardness of the rubber composition for the belt enters a predetermined range, and in the case of a friction transmission belt, the belt easily follows the pulley.

  According to the invention described in claim 2, the hardness after vulcanization of the rubber composition is 75 to 82 degrees when measured with a type A hardness meter of the spring type hardness test of JISK6301. Since the rubber composition for a belt described is present, the followability of the belt to the pulley is improved in friction transmission.

According to the invention described in claim 3, since the softener or plasticizer is at least one of paraffinic oil or naphthene, the rubber composition for belts according to claim 1 or 2, Tear resistance is further improved.

According to the invention described in claim 4, the tearing force is 50 to 70 N / mm. Since the rubber composition for a belt according to any one of claims 1 to 3, when used as a V-ribbed belt, the belt However, the ribs are not lost while driving.

According to the invention described in claim 5, in the V-ribbed belt comprising the adhesive rubber layer in which the core wire is embedded along the belt length direction and the compressed rubber layer having at least two rib portions extending in the belt length direction, Since at least the compressed rubber is a V-ribbed belt made of the rubber composition according to any one of claims 1 to 4, the belt can easily follow the pulley during traveling, and the tear resistance of the rubber is improved. No chipping occurs.

According to the invention described in claim 6, since the core wire diameter is 1.0 to 1.2 mm, since it is the V-ribbed belt according to claim 5, the tension variation of the belt is reduced, and the belt becomes a pulley. It becomes easy to follow.

  FIG. 1 is an example of a V-ribbed belt showing an example of using the rubber composition for a belt of the present invention at least as a compression rubber. The V-ribbed belt 1 is a polyester fiber cord, ethylene-2,6- Adhesive rubber layer 4 in which a core 3 made of a fiber cord, an aramid cord, or a nylon cord in which a polyester filament group mainly composed of naphthalate (PEN) is twisted is embedded, and a compression portion that is an elastic body layer below the adhesive rubber layer 4 It consists of six. The compression portion 6 has a plurality of trapezoidal ribs having a substantially triangular cross section extending in the belt longitudinal direction.

As the core 3, for example, a polyester fiber cord, a fiber cord in which a polyester filament group mainly composed of ethylene-2,6-naphthalate (PEN) is twisted, an aramid cord, or a nylon cord can be used. The ethylene-2,6-naphthalate used in the present invention is usually a polycondensation of naphthalene-2,6-dicarboxylic acid or an ester-forming derivative thereof with ethylene glycol in the presence of a catalyst under appropriate conditions. Is generated. At this time, if one or more appropriate third components are added before the polymerization of ethylene-2,6-naphthalate is completed, a copolymer polyester is synthesized.
A core wire diameter of 1.0 to 1.2 mm is preferably used. When the core wire diameter is smaller than 1.0 mm, the tension fluctuation during running of the belt is large, the belt is likely to slip, the belt vibration is also increased, and the sound is easily generated. On the other hand, if the core wire diameter is larger than 1.2 mm, the belt rigidity is increased, the belt is less likely to follow the pulley, and the occurrence of rib chipping is likely to occur.

  The rubber used for the belt rubber composition of the present invention includes natural rubber (NR), isoprene rubber (IR), ethylene-propylene-diene copolymer rubber (EPDM), chloroprene rubber (CR), alkylated chlorosulfone. Polyethylene (ACSM), hydrogenated nitrile rubber (HNBR), and styrene butadiene rubber (SBR) are used, but the hydrogenated nitrile rubber is not particularly limited, but the hydrogenation rate is 80% or more, and particularly heat resistant 90% or more is preferable for exhibiting the properties of heat resistance and ozone resistance.

  Carbon black is used as the filler mixed with the rubber in the rubber composition for belts of the present invention. Paraffinic oil or naphthene is used as the softener or plasticizer to be mixed. Regarding the amount of carbon black mixed with rubber, 40 to 50 parts by mass of carbon black is mixed with 100 parts by mass of rubber, and preferably 45 to 50 parts by mass of carbon black is mixed. If the filler is less than 40 parts by mass, the strength of the rubber composition is reduced. On the other hand, if the filler is more than 50 parts by mass, the hardness of the rubber composition becomes too high, and ribs are missing when used as a compressed rubber for a V-ribbed belt. Is likely to occur.

  The amount of the softener or plasticizer mixed with the rubber is preferably 5 to 10 parts by mass of the softener or plasticizer with respect to 100 parts by mass of the rubber. When the amount of the softening agent or plasticizer is less than 5 parts by mass, the hardness of the rubber composition becomes too high, and rib breakage is likely to occur when used as a compressed rubber for a V-ribbed belt. On the other hand, when the amount exceeds 10 parts by mass, the hardness of the rubber composition becomes too low, and when it is used as a compressed rubber for a V-ribbed belt, adhesive wear easily occurs between the pulleys.

  Moreover, the short fiber mixed with rubber can use the normally used short fiber about 1-10 mm in length which consists of fibers, such as cotton, polyester, polyamide, and aramid. As the amount of the short fibers to be mixed, it is preferable that 20 to 40 parts by mass of the short fibers are mixed with 100 parts by mass of the rubber.

  The rubber composition for belts obtained by the above mixing is vulcanized at a vulcanization temperature of 120 ° C. to 130 ° C. for 2 minutes to produce a sheet having a thickness of 2 mm, and the A type of the spring type hardness test of JISK6301 The hardness is preferably 75 to 82 degrees when measured with a hardness meter. When the hardness is less than 75 degrees, adhesion wear with the pulley is likely to occur when used as a compressed rubber for V-ribbed belts. On the other hand, when the hardness exceeds 82 degrees, this rubber composition is used as a compressed rubber for V-ribbed belts. In this case, rib breakage is likely to occur.

  Moreover, it is preferable that the tearing force of the rubber composition for belts of the present invention is 50 N / mm to 70 N / mm. If the tearing force of the rubber composition for belts is less than 50 N / mm, rib breakage tends to occur when used as a compressed rubber for V-ribbed belts. On the other hand, when the tearing force of the rubber composition for belts is greater than 70 N / mm, cracks are likely to occur in the compressed rubber at an early stage when used as a compressed rubber for a V-ribbed belt.

  The adhesive rubber layer 4 of the V-ribbed belt of the present invention includes hydrogenated nitrile rubber, chloroprene rubber, natural rubber, chlorosulfonated polyethylene (CSM), alkylated chlorosulfonated polyethylene (ACSM), styrene butadiene rubber (SBR), Ethylene-α-olefin elastomer (EPDM) is used, and hydrogenated nitrile rubber has a hydrogenation rate of 80% or more, and preferably 90% or more in order to exhibit heat resistance and ozone resistance characteristics. Hydrogenated nitrile rubber having a hydrogenation rate of less than 80% has extremely low heat resistance and ozone resistance. Considering oil resistance and cold resistance, the amount of bound acrylonitrile is preferably in the range of 20 to 45%. Among these, an ethylene-α-olefin elastomer having oil resistance and cold resistance is preferable.

  Next, a method for manufacturing the V-ribbed belt of the present invention will be described. Although it does not limit as a manufacturing method, For example, there exist the following methods.

  First, a member constituting the extension part and an adhesive rubber sheet constituting the adhesive layer are wound around the circumferential surface of the cylindrical molding drum, and then a cord made of a cord is spun spirally thereon, and further the compression part The compressed rubber sheets constituting the (power transmission unit) are sequentially wound to form an unvulcanized sleeve, and then vulcanized to obtain a vulcanized sleeve. Next, the vulcanization sleeve is hung on a driving roll and a driven roll and travels under a predetermined tension. Further, the rotated grinding wheel is moved so as to abut on the traveling vulcanization sleeve to compress the sleeve. A surface of 3 to 100 grooves is polished on the surface at a time to form a friction transmission surface. The sleeve thus obtained is removed from the driving roll and the driven roll, the sleeve is hung on the other driving roll and the driven roll, traveled, cut into a predetermined width by a cutter, and finished into individual V-ribbed belts. .

Next, a rubber sheet having a thickness of 2.0 mm was prepared by kneading rubber with the composition shown in Table 1, and vulcanized at a vulcanization temperature of 120 ° C. for 15 minutes. A of the spring type hardness test of JISK6301 A tear test was carried out by the hardness and the method of JISK6301 using a shape hardness tester. The results are shown in Table 2.

  Next, the V-ribbed belt of the present invention was manufactured. In the V-ribbed belt manufactured in this example, a core wire made of polyester fiber and having a diameter of 1.1 mm is embedded in the adhesive layer, and two plies of rubber cotton canvas are laminated on the upper side as an extension, and the other adhesive layer Three ribs are arranged in the longitudinal direction of the belt in a compression portion provided on the lower side of the belt.

  Here, the compression part was prepared from the rubber composition shown in Table 1, kneaded with a Banbury mixer, and then rolled with a calender roll. The compressed portion includes short fibers and is oriented in the belt width direction. The adhesive layer is a rubber composition prepared with a rubber composition obtained by removing short fibers from the rubber composition shown in Table 1.

  The belt manufacturing method is a known method. First, a two-ply cotton canvas with rubber is wound around a flat cylindrical mold, and then an adhesive rubber sheet constituting an adhesive layer is wound to spin the cord. And after arrange | positioning the compression rubber sheet which comprises a compression rubber layer, the jacket for vulcanization | cure is inserted on this compression rubber sheet. Next, the molding mold is placed in a vulcanizing can and vulcanized at 150 ° C. for 40 minutes at the pressure shown in FIG. 2. Then, the cylindrical vulcanizing sleeve is taken out of the mold, and the compressed rubber layer of the sleeve is removed by a grinder. It consists of a process of forming a rib and cutting the molded body into individual belts.

  As shown in FIG. 3, the hardness of the V-ribbed belt thus obtained is pressed against the center of the rib bottom with a JISK6301 spring type hardness tester A type hardness tester with a load of 5 kgf, and the hardness of the compressed rubber of the belt. Was measured. The results are shown in Table 3.

  And the heat-flexibility test of this belt was done. The results are shown in Table 3. The running test machine used for the evaluation of the heat-resistant flexibility test was configured by arranging a drive pulley (diameter 60 mm), an idler pulley (diameter 89 mm), a driven pulley (diameter 121 mm), and a tensioner pulley (diameter 70 mm) in this order. Is. Then, the V-ribbed belt 1 is hung on each pulley of the testing machine, and the running temperature is 110 ° C., the driving pulley is rotated at 1,500 rpm, and the belt tension is 1,500 N / rib. Time was measured. The results are shown in Table 3.

From the results shown in Table 3, in Comparative Examples 2 and 3 in which the amount of carbon black is large and the amount of paraffin oil is small compared to the examples, the time until the ribs are missing is considerably shortened. Further, in Comparative Example 1 in which the amount of carbon black was slightly large and the amount of paraffin oil was small, the time until the ribs were missing was shortened by about 50 hours compared to the example. Further, Comparative Example 4 having a large amount of carbon black and a large amount of paraffin oil also shortened the time until the rib was missing by about 50 hours as compared with the Examples.

  INDUSTRIAL APPLICABILITY The present invention can be used to improve the transmission force of rubber that comes into contact with pulleys such as V-belts and V-ribbed belts, and improve the tearing force of rubber.

It is a section perspective view of the V ribbed belt concerning the present invention. It is the graph which showed the vulcanization conditions of the V ribbed belt which concerns on this invention. It is the schematic which showed the hardness measuring method of the V-ribbed belt which concerns on this invention. It is a conceptual diagram which shows the layout of a running test.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 V-ribbed belt 2 Extension part 3 Core wire 4 Adhesive layer 5 Cover canvas 6 Compression part

Claims (6)

  A rubber composition for a belt, wherein 45 to 50 parts by mass of carbon black, 20 to 40 parts by mass of short fibers, and 5 to 10 parts by mass of a softener or a plasticizer are mixed with 100 parts by mass of rubber.   2. The rubber composition for a belt according to claim 1, wherein the rubber composition has a hardness after vulcanization of 75 to 82 degrees as measured with a photometer of type A in a spring type hardness test of JISK6301.   The rubber composition for a belt according to claim 1 or 2, wherein the softening agent or plasticizer is at least one of paraffinic oil or naphthene.   The rubber composition for a belt according to any one of claims 1 to 3, wherein the tearing force is 50 to 70 N / mm. 5. A V-ribbed belt comprising an adhesive rubber layer in which a core wire is embedded along the belt length direction and a compressed rubber layer having at least two rib portions extending in the belt length direction. A V-ribbed belt comprising the rubber composition according to any one of the above. The V-ribbed belt according to claim 5, wherein the core wire diameter is 1.0 to 1.2 mm.

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