JP2016204558A - Rubber composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a rubber composition which can improve the frictional wear properties of a rubber component.SOLUTION: A rubber composition comprises a rubber component, and cellulose fine fiber. A fiber diameter distribution range of the cellulose fine fiber is 50-500 nm.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a rubber composition.

  Rubber compositions containing so-called cellulose nanofibers are known. For example, Patent Document 1 discloses a vulcanized rubber composition containing a rubber component such as natural rubber and chemically modified microfibril cellulose.

Japanese Patent No. 4581116

  An object of the present invention is to provide a rubber composition capable of improving the friction and wear characteristics of rubber parts.

  The rubber composition of the present invention includes cellulosic fine fibers and a rubber component, and the fiber diameter distribution range of the cellulosic fine fibers includes 50 to 500 nm.

  Since the rubber composition of the present invention contains cellulosic fine fibers having a fiber diameter distribution range of 50 to 500 nm, it is excellent in behavioral stability under wet conditions.

FIG. 1 is a perspective view schematically showing a wrapped V-belt of the embodiment. 2A to 2G are explanatory views showing a method for manufacturing a wrapped V-belt.

  Hereinafter, embodiments will be described with reference to the drawings.

(Embodiment 1)
<Rubber composition>
The rubber composition according to Embodiment 1 includes a rubber component and cellulosic fine fibers, and the fiber diameter distribution range of the cellulosic fine fibers includes 50 to 500 nm. The rubber composition may contain various rubber compounding agents in addition to the cellulosic fine fibers.

(Rubber component)
Examples of the rubber component of the rubber composition include ethylene-α-olefin elastomers (EPDM, EPR, etc.), chloroprene rubber (CR), chlorosulfonated polyethylene rubber (CSM), hydrogenated acrylonitrile rubber (H-NBR), natural Examples thereof include rubber (NR), styrene butadiene rubber (SBR), butadiene rubber (BR), nitrile rubber (NBR), silicone rubber (Q), and fluorine rubber (FKM). Moreover, the blend rubber of 1 type, or 2 or more types of these may be sufficient.

(Cellulose fine fiber)
Cellulosic fine fibers are fiber materials derived from cellulose fine fibers composed of plant cell wall skeletal components obtained by finely loosening plant fibers. Examples of the cellulosic fine fiber plant include wood, bamboo, rice (rice straw), potato, sugar cane (bagasse), aquatic plants, and seaweed. Of these, wood is preferred. When the porous rubber composition forming the surface rubber layer 11a contains such cellulosic fine fibers, the high reinforcing effect is exhibited.

  The cellulosic fine fiber may be either the cellulosic microfiber itself or a hydrophobized hydrophobized cellulose microfiber. Moreover, you may use together cellulose fine fiber itself and hydrophobized cellulose fine fiber as a cellulosic fine fiber. From the viewpoint of dispersibility, the cellulosic fine fibers preferably include hydrophobized cellulose fine fibers. Examples of the hydrophobized cellulose fine fibers include cellulose fine fibers in which some or all of the hydroxyl groups of cellulose are substituted with hydrophobic groups, and cellulose fine fibers that have been subjected to a hydrophobized surface treatment with a surface treatment agent.

  Examples of the hydrophobization for obtaining cellulose fine fibers in which some or all of the hydroxyl groups of cellulose are substituted with hydrophobic groups include esterification (acylation) (alkyl esterification, complex esterification, β-ketoesterification, etc.) ), Alkylation, tosylation, epoxidation, arylation and the like. Of these, esterification is preferred. Specifically, in the esterified hydrophobized cellulose fine fiber, part or all of the hydroxyl groups of cellulose are carboxylic acids such as acetic acid, acetic anhydride, propionic acid, butyric acid, or halides thereof (particularly chlorides). It is the cellulose fine fiber acylated by. Examples of the surface treatment agent for obtaining cellulose fine fibers hydrophobized and surface-treated with the surface treatment agent include silane coupling agents.

  Cellulosic fine fibers preferably have a wide fiber diameter distribution from the viewpoint of improving the stability of behavior under wet conditions, and the fiber diameter distribution range includes 50 to 500 nm. From the viewpoint, the lower limit of the fiber diameter distribution is preferably 50 nm or less, more preferably 20 nm or less, and still more preferably 10 nm or less. From the same viewpoint, the upper limit is preferably 500 nm or more, more preferably 700 nm or more, and further preferably 1 μn or more. From the viewpoint of enhancing the reinforcing effect of the surface rubber layer 11a, the fiber diameter distribution range of the cellulosic fine fibers preferably includes 50 to 500 nm, more preferably includes 20 nm to 700 mm, and includes 10 nm to 1 μm. Further preferred.

  In addition, the average fiber diameter of the cellulosic fine fibers is preferably 10 nm or more, more preferably 30 nm or more, and preferably 1400 nm or less, more preferably, from the viewpoint of improving the stability of the behavior under wet conditions. 1000 nm or less, more preferably 800 nm or less.

  The distribution of the fiber diameter of the cellulosic fine fibers is obtained by freezing and crushing a sample of the rubber composition, then observing the cross section with a transmission electron microscope (TEM) and arbitrarily selecting 50 cellulosic fine fibers. The fiber diameter is measured and obtained based on the measurement result. The average fiber diameter of the cellulosic fine fibers is obtained as the number average of the fiber diameters of 50 arbitrarily selected cellulosic fine fibers.

  The cellulosic fine fibers may be of high aspect ratio manufactured by mechanical defibrating means, or of acicular crystals manufactured by chemical defibrating means. Moreover, you may use together what was manufactured by the mechanical defibration means, and what was manufactured by the chemical defibration means as a cellulose fine fiber. Examples of the defibrating apparatus used for the mechanical defibrating means include a kneader such as a twin-screw kneader, a high-pressure homogenizer, a grinder, and a bead mill. Examples of the treatment used for the chemical defibrating means include acid hydrolysis treatment.

  The content of the cellulosic fine fibers in the rubber composition is preferably 0.5 parts by mass or more, more preferably 1 part by mass or more, still more preferably 5 parts by mass or more, with respect to 100 parts by mass of the rubber component. The amount is preferably 30 parts by mass or less, more preferably 20 parts by mass or less, and still more preferably 10 parts by mass or less.

(Rubber compounding agents other than cellulosic fine fibers)
Examples of the rubber compounding agent used in addition to the cellulosic fine fibers include a reinforcing material, oil, and a crosslinking agent.

  As carbon black, for example, channel black; furnace black such as SAF, ISAF, N-339, HAF, N-351, MAF, FEF, SRF, GPF, ECF, N-234; FT, MT, etc. Thermal black; acetylene black and the like.

  The compounding amount of carbon black is preferably 15 parts by mass or more, more preferably 30 parts by mass or more, and preferably 100 parts by mass or less, more preferably 80 parts per 100 parts by mass of the rubber component of the rubber composition. It is below mass parts.

  Carbon black may have at least one of a hydroxyl group, a carbonyl group, and a carboxyl group.

  Silica is also mentioned as a reinforcing agent. Silica may be obtained by various methods such as a sol-gel method, a wet method, and a dry method. In particular, wet silica is preferred from the viewpoints of reinforcement and low heat build-up.

  The amount of silica is preferably 5 parts by mass or more, more preferably 10 parts by mass or more, and preferably 50 parts by mass or less, more preferably 30 parts by mass with respect to 100 parts by mass of the rubber component of the rubber composition. Or less.

  Moreover, when using silica, you may mix | blend a silane coupling agent. Examples of the silane coupling agent include sulfide systems such as bis- (3- (triethoxysilyl) propyl) polysulfide (S number of polysulfide moiety: 2 to 8), mercapto systems such as 3-mercaptopropyltrimethoxysilane, 3- Examples include silane coupling agents used for ordinary rubbers of amino type such as aminopropyltrimethoxysilane and vinyl type such as vinyltriethoxysilane. A silane coupling agent may use only a single kind, and may mix and use multiple types. The addition amount of the silane coupling agent is preferably 0.5 to 15 parts by mass with respect to 100 parts by mass of the rubber component. When kneading using a supercritical fluid, which will be described later, an effect of further enhancing the interaction between the polymer and the filler can be obtained by adding a silane coupling agent.

  Oils include, for example, petroleum-based softeners, mineral oils such as paraffin wax, castor oil, cottonseed oil, linseed oil, rapeseed oil, soybean oil, palm oil, palm oil, fall raw oil, wax, rosin, pine And vegetable oils such as oil. The oil is preferably one or more of these. The oil content is, for example, 5 to 15 parts by mass with respect to 100 parts by mass of the rubber component of the rubber composition.

  Examples of the crosslinking agent include organic peroxides and sulfur. As a crosslinking agent, an organic peroxide may be blended, sulfur may be blended, or both of them may be used in combination. In the case of an organic peroxide, the compounding amount of the crosslinking agent is, for example, 1 to 5 parts by mass with respect to 100 parts by mass of the rubber component of the rubber composition, and in the case of sulfur, with respect to 100 parts by mass of the rubber component of the rubber composition. For example, 1 to 5 parts by mass.

(Manufacture of rubber composition)
In producing the rubber composition, first, cellulose fine fibers are introduced into the kneaded rubber component and dispersed by kneading.

  Here, as a method for dispersing the cellulose-based fine fibers in the rubber component, for example, a dispersion (gel) in which the cellulose-based fine fibers are dispersed in water is added to the rubber component kneaded with an open roll, A method of vaporizing moisture while kneading them, a master of cellulose fine fibers / rubber obtained by mixing a dispersion (gel) in which cellulosic fine fibers are dispersed in water and rubber latex to vaporize the moisture Obtained by mixing the batch into a rubber component that has been masticated, mixing a dispersion in which cellulosic fine fibers are dispersed in a solvent, and a solution in which the rubber component is dissolved in the solvent, and evaporating the solvent. Cellulose fine fiber / rubber masterbatch is added to the kneaded rubber component, dispersion (gel) in which cellulose fine fiber is dispersed in water is freeze-dried and pulverized Things and how to put into a rubber component is masticated, methods and the like to introduce cellulosic microfibers made hydrophobic in rubber component is masticated.

  Next, while kneading the rubber component and the cellulosic fine fiber, the various rubber compounding agents described above are added and kneading is continued. For this purpose, a kneader such as a kneader or a Banbury mixer can be used.

  The uncrosslinked rubber composition obtained by the kneading step is molded and crosslinked by a usual molding and crosslinking step, whereby a crosslinked rubber composition is obtained.

  About a shaping | molding bridge | crosslinking process, you may use a press, a vulcanization can, a continuous vulcanizer etc., for example, and you may use the special bridge | crosslinking group etc. which bridge | crosslink by high frequency bridge | crosslinking, radiation bridge | crosslinking, or electron beam bridge | crosslinking.

  The molding crosslinking conditions such as temperature, pressure, and time are appropriately set based on the composition of the filler-containing uncrosslinked rubber, the required quality of the rubber molded product, and the like. In the molding and crosslinking step, the polymer molecules contained in the uncrosslinked rubber composition are crosslinked with a crosslinking agent to form a network structure. Thereby, a crosslinked rubber composition is obtained.

  Specific steps may be performed according to the type of rubber molded product to be manufactured. For example, when a wrapped V-belt as shown in FIG. 1 is manufactured, the following steps may be performed.

  The wrapped V-belt B illustrated in FIG. 1 is used for, for example, an agricultural machine or an industrial machine, and the dimensions thereof are, for example, a belt circumferential length of 700 to 5000 mm, a belt width of 16 to 17 mm, and a belt thickness of 8 -10 mm.

  The wrapped V-belt B has a cross-sectional shape configured as a triple layer of a bottom rubber layer 11 on the belt inner peripheral side (pulley contact side), an intermediate adhesive rubber layer 12 and an extended rubber layer 13 on the belt outer peripheral side. A trapezoidal belt body 10 is provided. A core wire 14 is embedded in the adhesive rubber layer 12 so as to form a spiral having a pitch in the belt width direction. The belt body 10 is entirely covered with a reinforcing cloth 15.

  The compressed rubber layer 11, the adhesive rubber layer 12, and the stretched rubber layer 13 are composed of a crosslinked rubber composition. And, at least one of the compressed rubber layer 11, the adhesive rubber layer 12, and the stretched rubber layer 13 is an uncrosslinked rubber composition in which a cellulosic fine fiber and various rubber compounding agents are blended and kneaded in a rubber component. The product is formed of a rubber composition that is heated and pressurized and crosslinked with a crosslinking agent.

  The core 14 is composed of a wire such as a twisted yarn such as polyethylene terephthalate (PET) fiber, polyethylene naphthalate (PEN) fiber, para-aramid fiber, vinylon fiber, or braided string. In order to give the core wire 14 adhesion to the V-ribbed belt main body 10, an adhesive treatment that is heated after being immersed in an RFL aqueous solution before molding and / or an adhesive treatment that is dried after being immersed in rubber paste is performed. Before the said process, the adhesion | attachment process heated after being immersed in the adhesive agent solution which consists of solutions, such as an epoxy resin and a polyisocyanate resin, may be performed as needed. The outer diameter of the core wire 14 is, for example, 0.1 to 2 mm.

  The reinforcing cloth 15 is made of, for example, a woven fabric, a knitted fabric, a non-woven fabric, or the like formed of yarns such as cotton, polyamide fiber, polyester fiber, and aramid fiber. In order to provide the adhesiveness to the belt main body 10, the reinforcing cloth 15 is coated with rubber paste on the surface on the side of the belt main body 10 and / or an adhesive treatment in which it is immersed in an RFL aqueous solution and heated before molding. Adhesive treatment for drying is applied.

  Next, a method for manufacturing the wrapped V-belt B according to the first embodiment will be described with reference to FIGS.

  First, a rubber sheet 11 ′ for the compression rubber layer, a rubber sheet 12 ′ for the adhesive rubber layer, a rubber sheet 13 ′ for the stretch rubber layer, a twisted yarn 14 ′ for the core wire, and a cloth 15 ′ for the reinforcing cloth prepare. At this time, among the rubber sheet 11 ′ for the compression rubber layer, the rubber sheet 12 ′ for the adhesive rubber layer, and the rubber sheet 13 ′ for the stretch rubber layer, those including the recycled rubber according to the first embodiment are the first embodiment. An uncrosslinked rubber composition obtained by kneading the recycled rubber and the rubber compounding agent is obtained by processing into a sheet shape using a calender roll or the like. Further, the twisted yarn 14 ′ for the core wire and the fabric 15 ′ for the reinforcing fabric are subjected to adhesion treatment.

  Next, as shown in FIG. 2A, the rubber sheet 11 'for the compression rubber layer is wound around the mantle 21 a plurality of times, and the rubber sheet 12' for the adhesive rubber layer is wound thereon. On top of that, as shown in FIG. 2 (b), the twisted yarn 14 'is wound spirally. Furthermore, as shown in FIG. 2 (c), a rubber sheet 12 'for the adhesive rubber layer and a rubber sheet 13' for the stretch rubber layer are wound in order to produce a cylindrical laminated structure 10 '.

  Next, as shown in FIG. 2 (d), the cylindrical laminated structure 10 ′ is cut into a predetermined width on the mantle 21 and then removed from the mantle 21.

  Next, as shown in FIG. 2 (e), the annular laminated structure 10 ′ is rotated while being wound around a pair of pulleys with the rubber sheet 11 ′ side for the compressed rubber layer facing outward. The volume is adjusted by obliquely cutting both sides of the laminated portion of the rubber sheet 11 'for use in a V shape.

  Subsequently, as shown in FIG. 2 (f), the outer periphery of the annular laminated structure 10 'is covered with a cloth 15'.

  Then, as shown in FIG. 2 (g), the lapped annular laminated structure 10 'is fitted into the groove 23 of the cylindrical mold 22, and it is placed in a vulcanizing can and heated and pressurized. At this time, the rubber component of the annular laminated structure 10 ′ is cross-linked to form the belt main body 10, and the twisted yarn 14 ′ is bonded and integrated to the belt main body 10 to form the core wire 14, and the cloth 15 ′ is the belt main body. The wrapped V-belt B according to the first embodiment is manufactured by being bonded and integrated with 10 to form the reinforcing cloth 15.

  In addition to the V belt, the rubber composition of the present invention can be used for various parts and products such as a transmission belt such as a V-ribbed belt, a toothed belt, and a flat belt, a conveyor belt, and a tire.

  The rubber composition of the examples will be described below. Each example is also described in Table 1.

<Example 1>
First, a dispersion in which powdered cellulose (trade name: KC Flock W-GK manufactured by Nippon Paper Industries Co., Ltd.) is dispersed in toluene is prepared, and the dispersion is collided with a high-pressure homogenizer to convert the powdered cellulose into cellulose fine fibers. The fiber was defibrated to obtain a dispersion in which cellulose fine fibers were dispersed in toluene. Accordingly, the cellulose fine fibers are produced by mechanical defibrating means and are not subjected to a hydrophobic treatment.

  Next, a dispersion in which cellulose fine fibers are dispersed in toluene, and H-NBR (trade name: Zetpol 2020, manufactured by Nippon Zeon Co., Ltd.) are dissolved in toluene and a plasticizer (trade name: W-260, manufactured by DIC) is added. The obtained solution was mixed, and toluene and a plasticizer were vaporized to prepare a master batch of cellulose fine fiber / H-NBR. In addition, content of each component in a masterbatch was 25 mass% for the cellulose-based fine fibers, 25 mass% for the plasticizer, and 50 mass% for H-NBR.

  Subsequently, EPDM was masticated, and a master batch was added thereto for kneading. The input amount of the master batch was such that the content of cellulosic fine fibers was 5 parts by mass with respect to 100 parts by mass of total EPDM.

  Then, EPDM and cellulose fine fibers are kneaded, and 30 parts by mass of reinforcing material carbon black FEF (manufactured by Tokai Carbon Co., Ltd., trade name: Seast SO) is added to 100 parts by mass of EPDM. 8 parts by mass of Petroleum Co., Ltd., trade name: Thumper 2280) and 5 parts by mass of cross-linking agent (trade name: Peroximon F-40, manufactured by NOF Corporation) are added to each other to continue kneading, thereby uncrosslinked rubber composition A product was made.

<Example 2>
In the same manner as in Example 1, a cellulosic fine fiber / EPDM master batch was produced. Subsequently, EPDM was masticated, and a master batch was added thereto for kneading. The input amount of the master batch was such that the content of cellulosic fine fibers was 5 parts by mass with respect to 100 parts by mass of total EPDM.

  And while kneading | mixing EPDM and a cellulose fine fiber, there are 30 mass parts of carbon black FEF as a reinforcing material and 10 masses of silica (Degussa, trade name: Ultrazil VN3) with respect to 100 mass parts of EPDM. Then, 8 parts by mass of oil and 5 parts by mass of oil and 5 parts by mass of the crosslinking agent were added and kneading was continued to prepare an uncrosslinked rubber composition. That is, 10 parts by mass of silica is further blended with respect to the blending of Example 1.

<Example 3>
In the same manner as in Example 1, a cellulosic fine fiber / EPDM master batch was produced. Subsequently, EPDM was masticated, and a master batch was added thereto for kneading. The input amount of the master batch was such that the content of cellulosic fine fibers was 5 parts by mass with respect to 100 parts by mass of total EPDM.

  And while knead | mixing EPDM and a cellulosic fine fiber, with respect to 100 mass parts of EPDM, 8 mass parts of oil and 5 mass parts of crosslinking agents are respectively added, and kneading is continued, and an uncrosslinked rubber composition is obtained. Produced. Compared to Example 1, the composition does not contain carbon black.

<Example 4>
In the same manner as in Example 1, a cellulosic fine fiber / EPDM master batch was produced. Subsequently, EPDM was masticated, and a master batch was added thereto for kneading. The input amount of the master batch was such that the content of the cellulosic fine fibers was 10 parts by mass with respect to 100 parts by mass of the total EPDM.

  And while knead | mixing EPDM and a cellulosic fine fiber, with respect to 100 mass parts of EPDM, 8 mass parts of oil and 5 mass parts of crosslinking agents are respectively added, and kneading is continued, and an uncrosslinked rubber composition is obtained. Produced. Compared with Example 1, the blending amount of the cellulosic fine fibers is 5 parts by mass, and the carbon black is not included.

<Comparative Example 1>
EPDM was masticated, and 8 parts by mass of oil and 5 parts by mass of a crosslinking agent were added to 100 parts by mass of EPDM, and kneading was continued to prepare an uncrosslinked rubber composition. Compared to Example 1, the composition does not contain cellulosic fine fibers and carbon black.

<Comparative example 2>
While EPDM is masticated, 30 parts by mass of carbon black FEF as a reinforcing material, 8 parts by mass of oil, and 5 parts by mass of a crosslinking agent are added to 100 parts by mass of EPDM, and then kneading is continued to be uncrosslinked. A rubber composition was prepared. Compared to Example 1, the composition does not contain cellulosic fine fibers.

(Test evaluation method)
<Average fiber diameter / fiber diameter distribution>
Samples collected for the rubber compositions crosslinked by press molding in Examples 1 to 4 were freeze pulverized and then observed with a scanning electron microscope (SEM), and 50 fibers were arbitrarily selected. Then, the fiber diameter was measured, and the number average was obtained to obtain the average fiber diameter. Moreover, the maximum value and minimum value of the fiber diameter were calculated | required among 50 cellulose fine fibers.

<Abrasion resistance and friction coefficient evaluation test>
About each of Examples 1-4 and Comparative Examples 1-2, the test piece of the rubber composition bridge | crosslinked by press molding was produced. The dimensions of the test piece are 5 mm square and 10 mm long.

  First, the initial mass of the test piece was measured. Thereafter, using a pin-on-disk type friction and wear tester, the surface of a 5 mm square surface of the test piece was brought into contact with the surface of a disk-shaped counterpart made of gray cast iron (FC200). A pressure of 0.8 MPa was applied to the test piece from above, the mating member was rotated so that the sliding speed was 0.25 m / sec, and the mass of the test piece after 4 hours was measured. The change from the initial mass was defined as the wear mass. Table 1 shows values that are ten times the wear mass in mg.

  This measurement was performed in a dry state. The temperature of the counterpart material was set to 60 ° C.

  In the same manner as described above, a 5 mm square surface of the test piece is used as a sliding surface and brought into contact with the surface of a counterpart material made of gray cast iron. The friction coefficient was measured by rotating the mating member so that the force was 0.25 m / sec and measuring the force.

  Such a measurement of the coefficient of friction was performed during drying, when wet, and when drying. The time of drying is a state in which the test piece and the counterpart material are sufficiently dried. In the wet state, water is dropped on the surface of the disk-shaped mating material, and water is also present between the test piece and the mating material. Moreover, after stopping dripping of water from a wet state, a peak occurs in the coefficient of friction during drying. Drying means the time when such a peak occurs.

(Test evaluation results)
The test results are shown in Table 1.

  According to Table 1, it can be seen that all of the fine cellulose fibers of Examples 1 to 4 have a wide fiber diameter distribution. In addition, Examples 1 and 2 in which cellulosic fine fibers and carbon black are used in combination have a smaller average fiber diameter than Examples 3 and 4 in which cellulosic fine fibers are used but carbon black is not used. In Example 2 using silica, the average, maximum, and minimum fiber diameters are all smaller than Example 1 in which silica is not used.

  Further, in Examples 1 and 2, no agglomerates having a diameter of 5 μm or more of the cellulosic fine fibers are observed, whereas in Examples 3 and 4, the presence thereof is confirmed. That is, in Examples 1 and 2, the dispersibility of the cellulosic fine fibers is superior to that in Examples 3 and 4.

  When it sees about an abrasion amount, it is 798 in the comparative example 1 which does not contain a cellulosic fine fiber and carbon black. On the other hand, it is 174 in Comparative Example 2 containing only carbon black, and 198 and 163 in Examples 3 and 4 using only cellulosic fine fibers. Therefore, the cellulose-based fine fibers can achieve the same wear resistance as that of carbon black. In Example 1 in which cellulosic fine fibers and carbon black are used in combination as reinforcing materials, it is 86, and in Example 2 in which silica is used, it is 94. Further, the wear resistance of the rubber composition is further improved.

  Looking at the coefficient of friction, in the case of Examples 1 and 2, the variation in the value at the time of drying, wetting and drying is 0.1. On the other hand, in Comparative Examples 1 and 2 that do not use cellulosic fine fibers, the friction coefficient greatly decreases when wet, and increases when dry, and the fluctuations are large (in order 1.2 and 1). .1). In Examples 3 and 4 using cellulosic fine fibers, the range of variation is 0.2, which is significantly improved compared to Comparative Examples 1 and 2 even though it is larger than Examples 1 and 2. ing.

  Thus, by blending together the cellulosic fine fibers and the carbon black, a rubber composition having a small variation in the coefficient of friction can be obtained under conditions where water exposure and drying occur. Accordingly, the rubber part made of such a rubber composition has a stable behavior under wet conditions.

  As described above, by using cellulosic fine fibers as the reinforcing material of the rubber composition, and further using carbon black together, it is possible to obtain a rubber part having high wear resistance and stable behavior under water conditions.

  The present invention is useful in the field of rubber compositions.

DESCRIPTION OF SYMBOLS 10 Belt main body 11 Bottom rubber layer 12 Adhesive rubber layer 13 Stretch rubber layer 14 Core wire 15 Reinforcement cloth 10 'Laminated structure 11' Rubber sheet 12 'Rubber sheet 13' Rubber sheet 14 'Yarn 15' Cloth 21 Mantle 22 Cylindrical mold 23 groove

Claims (7)

In a rubber composition containing a rubber component and cellulosic fine fibers,
A rubber composition, wherein a fiber diameter distribution range of the cellulosic fine fibers includes 50 to 500 nm. The rubber composition of claim 1,
A rubber composition comprising carbon black as a filler. The rubber composition of claim 2,
The carbon black has at least one of a hydroxyl group, a carbonyl group, and a carboxyl group. In any 1 rubber composition of Claims 1-3,
A rubber composition comprising silica as a filler. In the rubber composition of any one of Claims 1-4,
The rubber composition is an ethylene-α-olefin elastomer. In any one rubber composition of Claims 1-5,
The cellulosic fine fiber is produced by a mechanical defibrating means. In any one rubber composition of Claims 1-5,
The rubber composition according to claim 1, wherein the cellulosic fine fibers are produced by chemical defibrating means.

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