Crosslinked rubber composition and transmission belt using the same

Abstract

Excellent molding processability is obtained from the uncrosslinked rubber composition before crosslinking. [Solution] The crosslinked rubber composition is obtained by crosslinking an uncrosslinked rubber composition. The uncrosslinked rubber composition contains a first rubber component which is an ethylene-α-olefin elastomer in which the α-olefin is propylene, a second rubber component which is an ethylene-1-butenediene terpolymer, and a tackifier.

Description

[Technical Field]

[0001] The present invention relates to a crosslinked rubber composition and a power transmission belt using the same. [Background technology]

[0002] Ethylene-α-olefin elastomers are widely used as rubber components in crosslinked rubber compositions for forming rubber products. For example, Patent Documents 1 to 3 disclose the use of a blend rubber of ethylene propylene diene terpolymer and ethylene-1-butenediene terpolymer as a rubber component in a crosslinked rubber composition for a transmission belt. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 7458859 [Patent Document 2] Patent No. 7458860 [Patent Document 3] Patent No. 7458861 Summary of the Invention

[0004] The present invention provides a cross-linked rubber composition obtained by cross-linking an uncross-linked rubber composition, wherein the uncross-linked rubber composition contains a first rubber component which is an ethylene-α-olefin elastomer in which the α-olefin is propylene, a second rubber component which is an ethylene-1-butenediene terpolymer, and a tackifier.

[0005] The present invention is a power transmission belt at least a portion of which is formed from the crosslinked rubber composition of the present invention. [Brief explanation of the drawings]

[0006] [Figure 1] FIG. [Figure 2] FIG. DETAILED DESCRIPTION OF THE INVENTION

[0007] The crosslinked rubber composition X according to the embodiment is obtained by crosslinking the uncrosslinked rubber composition X'. The uncrosslinked rubber composition X' contains a first rubber component of an ethylene-α-olefin elastomer in which the α-olefin is propylene, a second rubber component of an ethylene-1-butenediene terpolymer (EBDM), and a tackifier.

[0008] In the case of a crosslinked rubber composition containing an ethylene propylene diene terpolymer or an ethylene propylene copolymer as a rubber component, the uncrosslinked rubber composition before crosslinking has low adhesiveness. Therefore, when the uncrosslinked rubber composition is used to form an uncrosslinked molded article, for example, when a sheet-shaped uncrosslinked rubber composition is laminated or when the uncrosslinked rubber composition is compounded with a fibrous member or the like, there is a problem that the molding processability is poor due to the poor adhesion of the uncrosslinked rubber composition.

[0009] To address this problem, according to the crosslinked rubber composition X of the embodiment, the uncrosslinked rubber composition X' before crosslinking contains a first rubber component of an ethylene-α-olefin elastomer in which the α-olefin is propylene, a second rubber component of EBDM, and a tackifier, thereby enabling the uncrosslinked rubber composition X' before crosslinking to have excellent moldability. This is thought to be because the tackiness of the uncrosslinked rubber composition X' before crosslinking is significantly enhanced by the interaction between the second rubber component and the tackifier.

[0010] Here, the first rubber component contains ethylene propylene diene terpolymer (EPDM) and / or ethylene propylene copolymer (EPR). Therefore, the first rubber component may be composed of only EPDM, only EPR, or a blend rubber of EPDM and EPR. From the viewpoint of obtaining excellent molding processability of the uncrosslinked rubber composition X' before crosslinking, it is preferable that the first rubber component contains EPDM.

[0011] The ethylene content of the first rubber component is preferably 40% by mass or more and 70% by mass or less, more preferably 45% by mass or more and 55% by mass or less, and even more preferably 50% by mass or more and 53% by mass or less, from the viewpoint of obtaining excellent molding processability of the uncrosslinked rubber composition X' before crosslinking.

[0012] When the first rubber component contains EPDM, examples of the diene component include 5-ethylidene-2-norbornene (ENB), 5-vinyl-2-norbornene (VNB), dicyclopentadiene, and 1,4-hexadiene. Among these, ENB is preferred as the diene component from the viewpoint of obtaining excellent moldability of the uncrosslinked rubber composition X' before crosslinking. In this case, the ENB content (diene content) of the EPDM contained in the first rubber component is preferably 4% by mass or more and 12% by mass or less, more preferably 6% by mass or more and 10% by mass or less, and even more preferably 7.5% by mass or more and 8.5% by mass or less, from the same viewpoints as above.

[0013] The ethylene content of the EBDM of the second rubber component is preferably 40% by mass or more and 60% by mass or less, more preferably 45% by mass or more and 55% by mass or less, and even more preferably 48% by mass or more and 52% by mass or less, from the viewpoint of obtaining excellent molding processability with the uncrosslinked rubber composition X' before crosslinking.

[0014] From the viewpoint of homogenizing the crosslinked rubber composition X after crosslinking, it is preferable that the difference between the ethylene content of the second rubber component and the ethylene content of the first rubber component is small. Specifically, from the same viewpoint as above, the difference between the ethylene content of the first rubber component and the ethylene content of the second rubber component is preferably 20% by mass or less, more preferably 10% by mass or less, even more preferably 7% by mass or less, still more preferably 5% by mass or less, and even more preferably 3% by mass or less. From the same viewpoint as above, it is preferable that the ethylene content of the second rubber component is the same as or less than the ethylene content of the first rubber component. From the same viewpoint as above, the ratio of the ethylene content of the second rubber component to the ethylene content of the first rubber component is preferably 0.7 or more and 1 or less, more preferably 0.85 or more and less than 1, even more preferably 0.9 or more and 0.99 or less, still more preferably 0.93 or more and 0.98 or less, and even more preferably 0.95 or more and 0.97 or less.

[0015] Examples of diene components of the second rubber component include ENB, VNB, dicyclopentadiene, and 1,4-hexadiene. Among these, ENB is preferred as the diene component from the viewpoint of obtaining excellent moldability of the uncrosslinked rubber composition X' before crosslinking. In this case, from the same viewpoint, the ENB content (diene content) of the EBDM of the second rubber component is preferably 4% by mass or more and 10% by mass or less, more preferably 6% by mass or more and 8% by mass or less, and even more preferably 6.5% by mass or more and 7.5% by mass or less.

[0016] When the first rubber component contains EPDM containing ENB as the diene component, it is preferable that the ENB content of the EBDM of the second rubber component be small in difference from the ENB content of the EPDM contained in the first rubber component, from the viewpoint of homogenizing the crosslinked rubber composition X after crosslinking. Specifically, from the same viewpoint as above, the difference between the ENB content of the EPDM contained in the first rubber component and the ENB content of the EBDM of the second rubber component is preferably 5% by mass or less, more preferably 3% by mass or less, even more preferably 2% by mass or less, and even more preferably 1.5% by mass or less. From the same viewpoint as above, it is preferable that the ENB content of the EBDM of the second rubber component be the same as or lower than the ENB content of the EPDM contained in the first rubber component. From the same viewpoint as above, the ratio of the ENB content of the EBDM of the second rubber component to the ENB content of the EPDM contained in the first rubber component is preferably 0.4 or more and 1 or less, more preferably 0.6 or more and less than 1, even more preferably 0.8 or more and 0.95 or less, still more preferably 0.83 or more and 0.93 or less, and still more preferably 0.85 or more and 0.9 or less.

[0017] The content A1 of the first rubber component in the uncrosslinked rubber composition X' may be greater than, less than, or the same as the content A2 of the second rubber component, but from the viewpoint of obtaining excellent moldability of the uncrosslinked rubber composition X' before crosslinking, it is preferably equal to or greater than the content A2 of the second rubber component. The mass ratio (A1 / A2) of the content A1 of the first rubber component to the content A2 of the second rubber component is preferably 50 / 50 or more and 90 / 10 or less, 55 / 45 or more and 80 / 20 or less, or 60 / 40 or more and 70 / 30 or less.

[0018] The uncrosslinked rubber composition X' may contain a rubber component other than the first and second rubber components in an amount less than the total amount of the first and second rubber components. Examples of the rubber component other than the first and second rubber components include ethylene-1-butene copolymer (EBR), chloroprene rubber (CR), and hydrogenated nitrile rubber (H-NBR).

[0019] Examples of tackifiers include phenolic resin-based tackifiers, petroleum resin-based tackifiers, rosin resin-based tackifiers, terpene resin-based tackifiers, and coumarone-indene resin-based tackifiers. Examples of phenolic resin-based tackifiers include alkylphenol resins, alkylphenol-formaldehyde resins, and phenol-formaldehyde resins. Examples of petroleum resin-based tackifiers include C5-C9 petroleum resins made from C5 fractions and C9 fractions, C5 petroleum resins made from C5 fractions, C9 petroleum resins made from C9 fractions, and dicyclopentadiene petroleum resins. Examples of rosin resin-based tackifiers include rosin ester resins and hydrogenated rosin ester resins. Examples of terpene resin-based tackifiers include polyterpene resins and styrene-modified terpene resins. Examples of coumarone-indene resin-based tackifiers include coumarone-indene resins and hydrogenated coumarone-indene resins. The tackifier preferably contains one or more of these. From the viewpoint of obtaining excellent moldability of the uncrosslinked rubber composition X' before crosslinking, it is preferable to contain a phenol resin-based tackifier and / or a petroleum resin-based tackifier, and more preferably an alkylphenol resin and / or a C5-C9 petroleum resin. Examples of commercially available alkylphenol resin tackifiers include Tamanol (registered trademark) 100S, 200N, 510, 521, 526, 586, and 7509 manufactured by Arakawa Chemical Industries, Ltd. Examples of commercially available C5-C9 petroleum resin tackifiers include Petrotack (registered trademark) 60, 70, 90, 90V, 90HS, and 100V manufactured by Tosoh Corporation.

[0020] From the viewpoint of obtaining excellent moldability of the uncrosslinked rubber composition X' before crosslinking, the content B of the tackifier in the uncrosslinked rubber composition X' is preferably 1 part by mass or more and 10 parts by mass or less, more preferably 2 parts by mass or more and 7 parts by mass or less, and even more preferably 3 parts by mass or more and 5 parts by mass or less, relative to 100 parts by mass of the total content of the first and second rubber components. From the same viewpoint as above, the mass ratio (B / A2) of the content B of the tackifier in the uncrosslinked rubber composition X' to the content A2 of the second rubber component is preferably 0.04 to 0.8, more preferably 0.05 to 0.2, and even more preferably 0.06 to 0.15.

[0021] The softening point of the tackifier is preferably 70° C. or higher and 100° C. or lower, from the viewpoint of obtaining excellent molding processability of the uncrosslinked rubber composition X′ before crosslinking while suppressing a decrease in hardness of the crosslinked rubber composition X after crosslinking. This softening point is measured by the ring and ball method.

[0022] The uncrosslinked rubber composition X' preferably contains a crosslinking agent for thermally crosslinking the first and second rubber components. Examples of the crosslinking agent include sulfur and organic peroxides. Examples of the organic peroxide include α,α'-di(t-butylperoxy)diisopropylbenzene, dicumyl peroxide, 1,3-bis(t-butylperoxyisopropyl)benzene, and 2,5-dimethyl-2,5-di(t-butylperoxy)hexane. The organic peroxide preferably contains one or more of these, and more preferably contains α,α'-di(t-butylperoxy)diisopropylbenzene. The crosslinking agent may be either sulfur or an organic peroxide, or both sulfur and an organic peroxide. The amount of sulfur in the uncrosslinked rubber composition X' is, for example, 2 to 4 parts by mass per 100 parts by mass of the total content of the first and second rubber components. The amount of the organic peroxide compounded in the uncrosslinked rubber composition X' is, for example, 2.5 parts by mass or more and 3.5 parts by mass or less per 100 parts by mass of the total amount of the first and second rubber components.

[0023] The uncrosslinked rubber composition X′ may further contain, as necessary, a reinforcing material such as carbon black, silica, or short fiber, a co-crosslinking agent, a process oil, a plasticizer, a processing aid, a vulcanization accelerator aid, a vulcanization accelerator, an antioxidant, etc.

[0024] The uncrosslinked rubber composition X' can be prepared by charging the first and second rubber components into a rubber mixer such as a kneader, a Banbury mixer, or an open roll mixer, masticating the mixture, and then adding rubber compounding ingredients containing a tackifier and a crosslinking agent and kneading them. The uncrosslinked rubber composition X' is then used to mold an uncrosslinked molded article, and the uncrosslinked molded article is heated and pressurized to crosslink the uncrosslinked rubber composition X', thereby obtaining the crosslinked rubber composition X according to the embodiment.

[0025] The crosslinked rubber composition X according to this embodiment can be suitably used to form at least a part of a transmission belt, for example.

[0026] Specifically, for example, in the V-belt B of the friction power transmission belt shown in Fig. 1, the rubber belt body 10 is composed of an adhesive rubber layer 101 in which core wires 11 are embedded, an inner compressed rubber layer 102 whose inner circumferential surface is covered with a reinforcing cloth 12, and an outer tensile rubber layer 103 whose outer circumferential surface is covered with a reinforcing cloth 13, and any one, two, or all three layers of the adhesive rubber layer 101, the compressed rubber layer 102, and the tensile rubber layer 103 can be formed from the crosslinked rubber composition X according to the embodiment. In the toothed belt C of the interlocking power transmission belt shown in Fig. 2, the rubber belt body 20 is composed of a back rubber portion 201 in which core wires 21 are embedded and a tooth rubber portion 202 covered with a reinforcing cloth 22, and one or both of the back rubber portion 201 and the tooth rubber portion 202 can be formed from the crosslinked rubber composition X. The core wires 11, 21 are provided with adhesive layers for bonding to the belt bodies 10, 20, and these adhesive layers can be formed from the crosslinked rubber composition X. Furthermore, the reinforcing fabrics 12, 13, 22 are provided with internal impregnated adhesive portions and / or internal adhesive layers for bonding to the belt bodies 10, 20, and these internal impregnated adhesive portions and / or internal adhesive layers can be formed from the crosslinked rubber composition X.

[0027] The manufacturing method of these V-belts B and toothed belts C may include a step of laminating a sheet-like uncrosslinked rubber composition X' and / or a step of compounding the uncrosslinked rubber composition X' with a core wire 11, 21 of a fiber member or a reinforcing fabric 12, 13, 22 to form a cylindrical uncrosslinked slab (uncrosslinked molded product), and a step of heating and pressurizing the uncrosslinked slab to crosslink the uncrosslinked rubber composition X' and form a crosslinked rubber composition X, thereby producing a cylindrical belt slab. In this case, the process of molding a cylindrical uncrosslinked slab includes a step of laminating sheet-like uncrosslinked rubber composition X' and / or a step of compounding uncrosslinked rubber composition X' with the core wires 11, 21 of the fiber member and the reinforcing cloths 12, 13, 22. Since the adhesiveness of uncrosslinked rubber composition X' is increased, high adhesion between sheets of sheet-like uncrosslinked rubber composition X' and / or high adhesion of uncrosslinked rubber composition X' to the core wires 11, 21 and the reinforcing cloths 12, 13, 22 can be obtained, and excellent molding processability can be obtained by using uncrosslinked rubber composition X' when molding the uncrosslinked slab.

[0028] The manufacturing method of V-belt B or toothed belt C may include a step of immersing core wires 11, 21 in a rubber cement prepared by dissolving uncrosslinked rubber composition X' in an organic solvent, followed by heating to perform an adhesion treatment, thereby coating the outer periphery of core wires 11, 21 with an overcoat layer of uncrosslinked rubber composition X'. The overcoat layer is formed at the adhesive layer at the interface between core wires 11, 21 and belt body 10, 20 when the uncrosslinked slab is heated and pressurized. At this time, high adhesion is imparted to core wires 11, 21 by the overcoat layer of uncrosslinked rubber composition X', and therefore excellent molding processability can be obtained when molding the uncrosslinked slab.

[0029] The manufacturing method of V-belt B or toothed belt C may include a step of soaking the reinforcing fabrics 12, 13, and 22 in a low-viscosity rubber cement prepared by dissolving uncrosslinked rubber composition X' in an organic solvent, followed by heating, thereby coating the yarn surfaces constituting the reinforcing fabrics 12, 13, and 22 with a soaked layer of uncrosslinked rubber composition X', and / or a step of coating the surface of the reinforcing fabrics 12, 13, and 22 facing the belt main bodies 10 and 20 with a high-viscosity rubber cement prepared by dissolving uncrosslinked rubber composition X' in an organic solvent, followed by heating, thereby coating the surface of the reinforcing fabrics 12, 13, and 22 facing the belt main bodies 10 and 20 with a coating layer of uncrosslinked rubber composition X'. The soaked layer is formed in an internal impregnation adhesive portion that covers the yarn surfaces inside the reinforcing fabrics 12, 13, and 22 when the uncrosslinked slab is heated and pressurized. The coating layer is formed on the inner adhesive layer of the reinforcing fabrics 12, 13, 22 at the interface with the belt main bodies 10, 20 when the uncrosslinked slab is heated and pressed. At this time, the soaking layer and / or coating layer of the uncrosslinked rubber composition X' provides high adhesiveness to the reinforcing fabrics 12, 13, 22, so that the soaking layer and / or coating layer of the uncrosslinked rubber composition X' provides excellent molding processability when molding the uncrosslinked slab. [Example]

[0030] (Uncrosslinked rubber composition) <Uncrosslinked rubber composition for adhesive rubber layer> The following uncrosslinked rubber compositions P1 to P4 were prepared for adhesive rubber layers. The compositions of each are also shown in Table 1.

[0031] -P1- The rubber component was a blend rubber obtained by mixing a first rubber component, EPDM1 (EP33 manufactured by ENEOS Materials, ethylene content: 52 mass%, ENB content: 8.1 mass%), and a second rubber component, EBDM (K-9330M manufactured by Mitsui Chemicals, ethylene content: 50 mass%, ENB content: 7.1 mass%), in a mass ratio of first rubber component / second rubber component = 50 / 50. To 100 parts by mass of the rubber component of this blend rubber of the first and second rubber components, 4 parts by mass of tackifier alkylphenol resin (Tamanol (registered trademark) 510 manufactured by Arakawa Chemical Industries, Ltd., softening point: 75 ° C to 95 ° C), 3 parts by mass of crosslinking agent sulfur (Seimi OT manufactured by Tsurumi Chemical Industry Co., Ltd.), 65 parts by mass of carbon black FEF, 20 parts by mass of silica, 4 parts by mass of short fiber cotton powder, 15 parts by mass of process oil, 1 part by mass of processing aid stearic acid, 5 parts by mass of vulcanization accelerator aid zinc oxide, and 3 parts by mass of vulcanization accelerator were blended and kneaded in a kneader to prepare an uncrosslinked rubber composition, designated P1. The kneading temperature was set to a temperature higher than the softening point of the tackifier.

[0032] Here, the difference in ethylene content between the first rubber component and the second rubber component is 2% by mass. The ratio of the ethylene content of the second rubber component to the ethylene content of the first rubber component is 0.96. The difference in ENB content between the EPDM of the first rubber component and the EBDM of the second rubber component is 1% by mass. The ratio of the ENB content of the EBDM of the second rubber component to the ENB content of the EPDM of the first rubber component is 0.88.

[0033] -P2- An uncrosslinked rubber composition was prepared in the same manner as P1, except that instead of alkylphenol resin, a C5-C9 petroleum resin (Petrotack (registered trademark) 90HS, softening point: 70°C to 100°C) was used as a tackifier in an amount of 4 parts by mass per 100 parts by mass of the total content of the first and second rubber components, and this was designated P2.

[0034] -P3- An uncrosslinked rubber composition was prepared in the same manner as P1 except that only the first rubber component EPDM1 was used as the rubber component and no tackifier was blended, and this was designated P3.

[0035] -P4- An uncrosslinked rubber composition was prepared in the same manner as P1 except that no tackifier was blended, and this was designated as P4.

[0036] [Table 1]

[0037] <Uncrosslinked rubber composition for overcoat layer> The following uncrosslinked rubber compositions Q1 to Q4 for the overcoat layer were prepared. The compositions of each are also shown in Table 2.

[0038] -Q1- A blend rubber was prepared by mixing the first rubber component (EPDM1) and the second rubber component (EBDM) in a 50 / 50 mass ratio. This blend rubber of the first and second rubber components was then mixed with 4 parts by mass of alkylphenol resin (tackifier), 3 parts by mass of sulfur (oil sulfur, manufactured by Hosoi Chemical Co., Ltd.) (crosslinking agent), 50 parts by mass of HAF (carbon black), 20 parts by mass of silica, 5 parts by mass of process oil, 1 part by mass of stearic acid (processing aid), 5 parts by mass of zinc oxide (vulcanization accelerator), and 3 parts by mass of vulcanization accelerator per 100 parts by mass of the rubber component. The uncrosslinked rubber composition was prepared by kneading in a kneader, designated Q1. The kneading temperature was set higher than the softening point of the tackifier.

[0039] -Q2- An uncrosslinked rubber composition was prepared in the same manner as Q1, except that, instead of alkylphenol resin, 4 parts by mass of C5-C9 petroleum resin was blended as a tackifier per 100 parts by mass of the total content of the first and second rubber components, and this was designated Q2.

[0040] -Q3- An uncrosslinked rubber composition was prepared in the same manner as in Q1 except that only the first rubber component EPDM1 was used as the rubber component and no tackifier was blended, and this was designated Q3.

[0041] -Q4- An uncrosslinked rubber composition was prepared in the same manner as Q1 except that no tackifier was blended, and this was designated Q4.

[0042] [Table 2]

[0043] <Uncrosslinked rubber composition for compression rubber layer> The following uncrosslinked rubber composition R for the compression rubber layer was prepared. The composition is also shown in Table 3.

[0044] EPDM1 was used as the rubber component. 100 parts by mass of the rubber component was blended with 4 parts by mass of alkylphenol resin as a tackifier, 7 parts by mass (2.8 parts by mass of active ingredient) of α,α'-di(t-butylperoxy)diisopropylbenzene (Peroximon F-40, manufactured by NOF Corporation, purity: 40%) as an organic peroxide as a crosslinking agent, 60 parts by mass of HAF as carbon black, 15 parts by mass of aramid short fiber, 1.5 parts by mass of a co-crosslinking agent, 5 parts by mass of process oil, 0.25 parts by mass of stearic acid as a processing aid, 5 parts by mass of zinc oxide as a vulcanization accelerator aid, and 2.5 parts by mass of an antioxidant, and the blended mixture was kneaded in a kneader to prepare an uncrosslinked rubber composition, designated R.

[0045] [Table 3]

[0046] (tackiness test) <Test piece> Each of the uncrosslinked rubber compositions P1 to P4 for adhesive rubber layers and the uncrosslinked rubber composition R for compression rubber layers was molded into a sheet. A strip-shaped test piece for a tackiness test was cut out from each sheet of the uncrosslinked rubber composition.

[0047] Each of the uncrosslinked rubber compositions Q1 to Q4 for the overcoat layer was dissolved in an organic solvent to prepare a rubber paste. A core wire made of RFL-treated polyester fiber was immersed in each rubber paste, pulled out, and then heated and dried to coat the core wire with an overcoat layer of Q1 to Q4. The core wire coated with the overcoat layer was cut into several short pieces, which were then attached in parallel to a rectangular sheet substrate in close contact with each other to prepare test specimens for the tackiness test.

[0048] <Test method and results> The tackiness test was carried out using a pickup-type tack meter (Tack Tester IMC-1567, manufactured by Imoto Machinery Co., Ltd.). The tack meter has a cylindrical aluminum adhesive disc with a diameter of 50 mm and a thickness of 14 mm, with its axis extending horizontally back and forth, and a fixing plate below it for setting the test piece. The adhesive disc has its upper end connected to a load cell and is movable up and down together with the load cell. The specific test method is as follows.

[0049] One test piece was attached to the outer periphery of the adhesive disk on the fixed plate side with double-sided tape, and the other test piece was attached horizontally to the fixed plate with double-sided tape. The adhesive disk was lowered at a speed of 30 mm / min so as to approach the fixed plate, and one test piece was pressed against the other test piece with a load of 4.9 N. After 10 seconds, the adhesive disk was raised at a speed of 30 mm / min so as to separate from the fixed plate. The peel force (tack force) when one test piece peeled from the other test piece was measured with a load cell.

[0050] In Test 1, the test piece on the disk side of the adhesive joint was designated P1. The peel strength was measured for each of Example 1, Example 2, and Example 3, in which the test piece on the fixed plate side was designated Q2, Q3, and R, respectively.

[0051] In Test 2, the test piece on the disk side of the adhesive joint was designated P2. The peel strength was measured for each of Example 4, Example 5, and Example 6, in which the test piece on the fixed plate side was designated Q2, Q3, and R, respectively.

[0052] In Test 3, the test piece on the adhesive disk side was designated P3. The peel strength was measured for Example 7, in which the test piece on the fixed plate side was designated Q2, Comparative Example 1, in which it was designated Q3, and Comparative Example 2, in which it was designated R.

[0053] In Test 4, the test piece on the adhesive disk side was designated P4. The test piece on the fixed portion side was designated Q1 in Example 8, Q2 in Example 9, Q3 in Comparative Example 3, Q4 in Comparative Example 4, and R in Comparative Example 5, and the peel strength was measured for each of them.

[0054] The test results are shown in Tables 4 and 5. Table 4 shows the test results of Tests 1 to 4 when the test pieces on the adhesive disc side were P1 to P4, respectively. Table 5 shows the test results when the test pieces on the fixed part side were Q1 to Q4 and R, respectively.

[0055] [Table 4]

[0056] [Table 5] [Industrial Applicability]

[0057] The present invention is useful in the technical fields of crosslinked rubber compositions and power transmission belts using the same. [Explanation of symbols]

[0058] BV Belt C Toothed belt 10,20 Belt body 101 adhesive rubber layer 102 Compressed rubber layer 103 tension rubber layer 11,21 Core wire 12,13,22 Reinforcement fabric 201 Back elastic 202 Tooth rubber part

Claims

1. A crosslinked rubber composition obtained by crosslinking an uncrosslinked rubber composition, The uncrosslinked rubber composition is a crosslinked rubber composition containing a first rubber component of an ethylene-α-olefin elastomer in which the α-olefin is propylene, a second rubber component of an ethylene-1-butenediene terpolymer, and a tackifier.

2. A power transmission belt at least a portion of which is formed from the crosslinked rubber composition according to claim 1.

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