Composition for power transmission belts, molded articles, crosslinked molded articles, and power transmission belts

Abstract

To provide a transmission belt composition that has excellent processability, a modulus suitable for transmission belts, and can form a transmission belt with excellent wear resistance. [Solution] A copolymer (S1) having structural units derived from ethylene [A1], structural units derived from α-olefin [B1] having 4 to 20 carbon atoms, and structural units derived from non-conjugated polyene [C1] containing a total of two or more substructures selected from the group consisting of the following formulas (I) and (II) in one molecule, wherein the structural units derived from [B1] include structural units derived from 1-butene, and the structural units derived from [C1] include structural units derived from 5-vinyl-2-norbornene; a copolymer (S2) having structural units derived from ethylene [A2], structural units derived from propylene, and structural units derived from non-conjugated polyene [C2] containing a total of two or more substructures selected from the group consisting of the following formulas (I) and (II) in one molecule; carbon black (B); and short fibers (C). JPEG2026058902000011.jpg25130

Description

[Technical Field]

[0001] The present invention relates to a composition for power transmission belts, a molded article, a crosslinked molded article, and a power transmission belt. [Background technology]

[0002] Power transmission belts are widely used in automobiles, motorcycles, and general industrial machinery. These belts require high rubber elasticity and abrasion resistance. Chloroprene rubber is typically used to manufacture power transmission belts that meet these properties. However, in response to the need for improved heat and cold resistance, as well as weight reduction, the use of ethylene-α-olefin-non-conjugated polyene copolymer rubber instead of chloroprene rubber is being considered (see, for example, Patent Documents 1-2).

[0003] A composition containing an ethylene-propylene-non-conjugated polyene copolymer has been disclosed as a suitable composition for transmission belts that have excellent heat resistance and abrasion resistance (Patent Document 3). [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2001-310951 [Patent Document 2] Japanese Patent Publication No. 2012-215212 [Patent Document 3] Japanese Patent Publication No. 2021-042316 [Overview of the project] [Problems that the invention aims to solve]

[0005] However, it has been found that conventional power transmission belt compositions are not necessarily sufficient in terms of achieving both processability and wear resistance of power transmission belts formed from these compositions.

[0006] The object of the present invention is to provide a composition for power transmission belts that has excellent processability, a modulus (tensile stress) suitable for power transmission belts, and excellent wear resistance, and that can form such power transmission belts. [Means for solving the problem]

[0007] The inventors of the present invention have diligently studied to solve the above problems and have found that the above problems can be solved according to the following embodiments, and have completed the present invention. Embodiments of the present invention are shown below.

[0008] [1] It has a structural unit derived from ethylene [A1], a structural unit derived from α-olefin [B1] having 4 to 20 carbon atoms, and a structural unit derived from a non-conjugated polyene [C1] containing a total of two or more substructures selected from the group consisting of the following general formulas (I) and (II) in one molecule. The structural unit derived from the α-olefin [B1] having 4 to 20 carbon atoms includes a structural unit derived from 1-butene, The structural units derived from the aforementioned non-conjugated polyene [C1] include structural units derived from 5-vinyl-2-norbornene in an ethylene-α-olefin-non-conjugated polyene copolymer (S1), An ethylene-propylene-non-conjugated polyene copolymer (S2) having structural units derived from ethylene [A2], structural units derived from propylene, and structural units derived from a non-conjugated polyene [C2] containing a total of two or more substructures selected from the group consisting of the following general formulas (I) and (II) in one molecule, Carbon black (B) and, A composition for power transmission belts containing short fibers (C).

[0009] [ka]

[0010] [2] The copolymer (S1) satisfies the following requirements (1-1) to (1-4) and is the transmission belt composition according to [1]: Requirement (1-1): The molar ratio [[A1] / [B1]] of structural units derived from ethylene [A1] to structural units derived from α-olefins [B1] with 4 to 20 carbon atoms is 40 / 60 to 90 / 10; Requirements (1-2): The content of structural units derived from non-conjugated polyenes [C1] is 0.1 to 6.0 mol%, with the total of structural units derived from ethylene [A1], α-olefins with 4 to 20 carbon atoms [B1], and non-conjugated polyenes [C1] being 100 mol%; Requirements (1-3): The B value, expressed by the following formula (1a), is 1.20 or greater; B value = ([EX] + 2[Y]) / [2 × [E] × ([X] + [Y])] ... Equation (1a) [Here, [E], [X], and [Y] represent the mole fractions of structural units derived from ethylene [A1], α-olefins with 4 to 20 carbon atoms [B1], and non-conjugated polyenes [C1], respectively, and [EX] represents the ethylene [A1]-α-olefins with 4 to 20 carbon atoms [B1] dyad chain fraction.] Requirements (1-4): The number of branching points per molecular chain, BrNo, obtained using 3D-GPC, satisfies the following equation (1b). BrNo≧0.5 …Formula (1b)

[0011] [3] The copolymer (S1) satisfies one or more of the following requirements (1-5) to (1-8) in the transmission belt composition according to [1] or [2]: Requirements (1-5): The weight-average molecular weight (Mw) of the copolymer (S1), the mass fraction of structural units derived from the non-conjugated polyene [C1] (mass fraction of [C1] (mass%)), and the molecular weight of the non-conjugated polyene [C1] (molecular weight of [C1]) satisfy the following formula (1c); 4.5 ≤ Mw × mass fraction of [C1] / 100 / molecular weight of [C1] ≤ 150 …Equation (1c) Requirements (1-6): Complex viscosity η at frequency ω = 0.1 rad / s, obtained by linear viscoelastic measurement (190°C) using a rheometer. * ( ω =0.1) (Pa·s) and complex viscosity η at frequency ω = 100 rad / s *( ω =100) The ratio P of [η] to (Pa·s) * ( ω =0.1) / η * ( ω =100) 〕, the intrinsic viscosity [η] of the copolymer (S1), and the mass fraction of the [C1] satisfy the following formula (1d); P / ([η] 2.9 ) ≤ mass fraction of [C1] × 6 … Formula (1d) Requirement (1-7): The complex viscosity η at a frequency ω = 0.01 rad / s obtained by linear viscoelastic measurement (190 °C) using a rheometer * ( ω =0.01) (Pa·s), the complex viscosity η at a frequency ω = 10 rad / s * ( ω =10) (Pa·s), and the apparent iodine value derived from the non-conjugated polyene [C1] satisfy the following formula (1e); Log{η * ( ω =0.01)} / Log{η * ( ω =10)} ≤ 0.0753 × {apparent iodine value derived from the non-conjugated polyene [C1]} + 1.42 … Formula (1e) Requirement (1-8): The glass transition temperature (Tg) measured by differential scanning calorimetry (DSC) is -65 °C or lower.

[0012] [4] The mass fraction of the copolymer (S1) in the total mass of the copolymer (S1) and the copolymer (S2) is 5% by mass or more and less than 100% by mass, the transmission belt composition according to any one of [1] to [3].

[0013] [5] The copolymer (S2) contains a structural unit derived from 5-vinyl-2-norbornene as a structural unit derived from the non-conjugated polyene [C2], the transmission belt composition according to any one of [1] to [4].

[0014] [6] The transmission belt composition according to any one of [1] to [5], wherein the content of the short fibers (C) is 0.1 to 100 parts by mass with respect to 100 parts by mass of the total of the copolymer (S1) and the copolymer (S2).

[0015] [7] A transmission belt composition according to any one of [1] to [6], wherein the short fiber (C) is an aramid short fiber.

[0016] [8] A transmission belt composition according to any one of [1] to [7], wherein the Mooney viscosity ML(1+4)100℃ of the copolymer (S1) is 5 to 150.

[0017] [9] A transmission belt composition according to any one of [1] to [8], further comprising an organic peroxide as a crosslinking agent (D).

[0018]

[10] A transmission belt composition according to any one of [1] to [9], further containing 0.1 to 20 parts by mass of a processing aid (F) per 100 parts by mass of the copolymer (S1) and the copolymer (S2) in total.

[0019]

[11] A transmission belt composition according to any one of [1] to

[10] , further containing a crosslinking aid (E).

[0020]

[12] A molded body formed from a transmission belt composition described in any of [1] to

[11] .

[0021]

[13] A transmission belt having the molded body described in

[12] .

[0022]

[14] A crosslinked molded article formed from a transmission belt composition described in any of [1] to

[11] .

[0023]

[15] A transmission belt having the crosslinked molded body described in

[14] . [Effects of the Invention]

[0024] According to the present invention, it is possible to provide a transmission belt composition that can form a transmission belt that has excellent processability, a modulus (tensile stress) suitable for transmission belts, and excellent wear resistance. [Modes for carrying out the invention]

[0025] The present invention will be described in detail below.

[0026] [Composition for power transmission belts] The transmission belt composition of the present invention (hereinafter also referred to as "this composition") comprises the following: ethylene-α-olefin-non-conjugated polyene copolymer (S1), ethylene-propylene-non-conjugated polyene copolymer (S2), carbon black (B), and short fibers (C).

[0027] <Ethylene-α-olefin-nonconjugated polyene copolymer (S1)> This composition contains an ethylene-α-olefin-non-conjugated polyene copolymer (S1) (hereinafter also referred to as "polymer (S1)"). Copolymer (S1) has structural units derived from ethylene [A1], structural units derived from α-olefin [B1] having 4 to 20 carbon atoms, and structural units derived from non-conjugated polyene [C1] containing a total of two or more substructures selected from the group consisting of the following general formulas (I) and (II) in one molecule. The structural unit derived from the α-olefin [B1] having 4 to 20 carbon atoms includes a structural unit derived from 1-butene, The structural units derived from the non-conjugated polyene [C1] include structural units derived from 5-vinyl-2-norbornene.

[0028] [ka]

[0029] Examples of α-olefins [B1] having 4 to 20 carbon atoms include 1-butene, 1-nonene, 1-decene, 1-nonadecene, 1-eicosene, etc., which have a straight chain structure without a side chain, and 4-methyl-1-pentene, 9-methyl-1-decene, 11-methyl-1-dodecene, 12-ethyl-1-tetradecene, etc., which have a side chain. Since the structural units of the copolymer (S1) derived from α-olefins [B1] with 4 to 20 carbon atoms include structural units derived from 1-butene, at least 1-butene is used as the α-olefin [B1].

[0030] These α-olefins [B1] can be used alone with 1-butene or in combination of two or more containing 1-butene. When α-olefins [B1] are used in combination with 1-butene, α-olefins having 4 to 10 carbon atoms are preferred, with 1-hexene and 1-octene being more preferred.

[0031] Examples of non-conjugated polyenes [C1] containing a total of two or more substructures selected from the group consisting of the above general formulas (I) and (II) in one molecule include 5-vinyl-2-norbornene (VNB), norbornadiene, 1,4-hexadiene, and dicyclopentadiene. Since the structural units derived from the non-conjugated polyene [C1] of the copolymer (S1) include structural units derived from 5-vinyl-2-norbornene (VNB), at least VNB is used as the non-conjugated polyene [C1].

[0032] These non-conjugated polyenes [C1] can be used as VNB alone or in combination of two or more containing VNB. It is preferable to use VNB alone because it is readily available, crosslinks well with organic peroxides, and improves the heat resistance of the composition.

[0033] The copolymer (S1) may further contain structural units derived from ethylene [A1], α-olefins having 4 to 20 carbon atoms [B1], and non-conjugated polyenes [C1], as well as structural units derived from non-conjugated polyenes [CX] that contain only one substructure selected from the group consisting of the above general formulas (I) and (II) in each molecule.

[0034] Examples of such non-conjugated polyenes [CX] include 5-ethylidene-2-norbornene (ENB), 5-methylene-2-norbornene, 5-(2-propenyl)-2-norbornene, 5-(3-butenyl)-2-norbornene, 5-(1-methyl-2-propenyl)-2-norbornene, 5-(4-pentenyl)-2-norbornene, 5-(1-methyl-3-butenyl)-2-norbornene, 5-(5-hexenyl)-2-norbornene, 5-(1-methyl-4-pentenyl)-2-norbornene, 5-(2,3-dimethyl-3-butenyl)-2-norbornene, and 5-(2-ethyl-3-butenyl) Examples include 5-(6-heptenyl)-2-norbornene, 5-(3-methyl-5-hexenyl)-2-norbornene, 5-(3,4-dimethyl-4-pentenyl)-2-norbornene, 5-(3-ethyl-4-pentenyl)-2-norbornene, 5-(7-octenyl)-2-norbornene, 5-(2-methyl-6-heptenyl)-2-norbornene, 5-(1,2-dimethyl-5-hexenyl)-2-norbornene, 5-(5-ethyl-5-hexenyl)-2-norbornene, and 5-(1,2,3-trimethyl-4-pentenyl)-2-norbornene. Among these, ENB is preferred due to its high availability, ease of controlling the crosslinking rate during crosslinking with organic peroxides, and ease of obtaining good mechanical properties. The non-conjugated polyene [CX] may be used alone or in combination of two or more types.

[0035] If the copolymer (S1) contains constituent units derived from a non-conjugated polyene [CX], the mass fraction thereof is preferably 0 to 20% by mass, more preferably 0 to 10% by mass, and even more preferably 0.01 to 8% by mass, relative to the total constituent units of the copolymer (S1).

[0036] Each copolymer (S1) may contain at least one biomass-derived monomer (ethylene [A1], α-olefin with 4 to 20 carbon atoms [B1], non-conjugated polyene [C1], non-conjugated polyene [CX]). Examples of biomass-derived α-olefins include biomass-derived 1-butene. Examples of biomass-derived non-conjugated polyenes include biomass-derived 5-vinyl-2-norbornene. The monomers used as raw materials for copolymer (S1) may contain only biomass-derived monomers, or they may contain both biomass-derived monomers and fossil fuel-derived monomers. Biomass-derived monomers such as biomass-derived ethylene, biomass-derived α-olefins, and biomass-derived non-conjugated polyenes can be obtained by known methods. It is preferable for copolymer (S1) to contain constituent units derived from biomass-derived monomers from the viewpoint of reducing environmental impact.

[0037] Each copolymer (S1) may contain at least one constituent unit derived from chemically recycled monomers. The chemically recycled monomers used as raw materials for copolymer (S1) may be chemically recycled ethylene, chemically recycled α-olefins, or chemically recycled non-conjugated polyenes. Furthermore, the monomers used as raw materials for copolymer (S1) may consist solely of chemically recycled monomers, or may consist of both chemically recycled monomers and fossil fuel-derived monomers. Chemically recycled monomers such as chemically recycled ethylene, chemically recycled α-olefins, and chemically recycled non-conjugated polyenes can be obtained by known methods. It is preferable for copolymer (S1) to contain constituent units derived from chemically recycled monomers from the viewpoint of reducing environmental impact (mainly waste reduction).

[0038] The copolymer (S1) preferably satisfies the following requirements (1-1) to (1-4). Requirements (1-1) The molar ratio [[A1] / [B1]] of structural units derived from ethylene [A1] to structural units derived from α-olefins [B1] with 4 to 20 carbon atoms is 40 / 60 to 90 / 10. Copolymers (S1) with a molar ratio within this range exhibit an excellent balance between rubber elasticity at low temperatures and tensile stress at room temperature.

[0039] The lower limit of the above molar ratio [[A1] / [B1]] is preferably 45 / 55, more preferably 50 / 50, even more preferably 55 / 45, and particularly preferably 60 / 40. The upper limit of the above molar ratio [[A1] / [B1]] is preferably 80 / 20, more preferably 75 / 25, even more preferably 70 / 30, and particularly preferably 68 / 32. The molar ratio [[A1] / [B1]] is, 1 It can be measured using H-NMR spectroscopy, etc.

[0040] Requirements (1-2) The content of structural units derived from non-conjugated polyene [C1] is 0.1 to 6.0 mol%, with the total of structural units derived from ethylene [A1], structural units derived from α-olefins [B1] having 4 to 20 carbon atoms, and structural units derived from non-conjugated polyene [C1] being 100 mol%. Copolymers (S1) with this content within the above range have sufficient crosslinkability and flexibility. The content ratio of each structural unit in the copolymer (S1) is: 13 It can be measured using C-NMR spectroscopy, etc.

[0041] The lower limit of the content of structural units derived from non-conjugated polyene [C1] is preferably 0.2 mol%, more preferably 0.3 mol%. The upper limit of the content of structural units derived from non-conjugated polyene [C1] is preferably 4.0 mol%, more preferably 3.0 mol%, even more preferably 2.0 mol%, and particularly preferably 1.0 mol%. When the content of structural units derived from non-conjugated polyene [C1] is within the above range, a copolymer (S1) with sufficient crosslinkability and flexibility is obtained.

[0042] Requirements (1-3) The B value represented by the following formula (1a) is 1.20 or greater, preferably 1.20 to 1.80, more preferably 1.25 to 1.60, even more preferably 1.30 to 1.45, and particularly preferably in the range of 1.35 to 1.42. B value = ([EX] + 2[Y]) / [2 × [E] × ([X] + [Y])] ... Equation (1a) [Here, [E], [X], and [Y] represent the mole fractions of structural units derived from ethylene [A1], α-olefins with 4 to 20 carbon atoms [B1], and non-conjugated polyenes [C1], respectively, and [EX] represents the ethylene [A1]-α-olefins with 4 to 20 carbon atoms [B1] dyad chain fraction.]

[0043] Copolymers (S1) that satisfy requirements (1-3) tend to have an excellent balance between rubber elasticity at low temperatures and tensile stress at room temperature. The B value is an indicator of the randomness of the copolymer monomer chain distribution in the copolymer (S1), and in formula (1a) above, [E], [X], [Y], and [EX] are, 13 The 1C-NMR spectrum can be measured and determined based on reports by J. C. Sandall [Macromolecules, 15, 353 (1982)], J. Ray [Macromolecules, 10, 773 (1977)], et al.

[0044] Requirements (1-4) The number of branching points per molecular chain, BrNo, obtained using 3D-GPC, satisfies the following equation (1b). BrNo≧0.5 …Formula (1b) Here, the number of branching points per molecular chain, BrNo, can be determined by structural analysis using 3D-GPC. Specifically, in this specification, it was determined as described in the examples below.

[0045] The copolymer (S1) more preferably satisfies the following formula (1b-1). BrNo≧0.8 …Formula (1b-1) When the number of branching points per molecular chain satisfies the above formula (1b) or (1b-1), it is preferable because the crosslinking rate is excellent when a crosslinked molded article is manufactured, and the molded article after crosslinking exhibits excellent mechanical properties.

[0046] The copolymer (S1) more preferably satisfies the following formula (1b-2). 3.0≧BrNo …Formula (1b-2) When the number of branching points per molecular chain satisfies the above equation (1b-2), it is preferable because the compression set at low temperatures is small, and the balance between rubber elasticity at low temperatures and tensile stress at room temperature is excellent.

[0047] The copolymer (S1) is preferably further satisfied with one or more of the following requirements (1-5) to (1-8), more preferably satisfied with two or more of the following requirements (1-5) to (1-8), even more preferably satisfied with three or more of the following requirements (1-5) to (1-8), and particularly preferably satisfied with all of the following requirements (1-5) to (1-8).

[0048] Requirements (1-5) The weight-average molecular weight (Mw) of the copolymer (S1), the mass fraction of structural units derived from the non-conjugated polyene [C1] (mass fraction of [C1] (mass%)), and the molecular weight of the non-conjugated polyene [C1] (molecular weight of [C1]) satisfy the following formula (1c). 4.5 ≤ Mw × mass fraction of [C1] / 100 / molecular weight of [C1] ≤ 150 …Equation (1c)

[0049] When the copolymer (S1) satisfies requirements (1-5), it is preferable because the content of structural units derived from non-conjugated polyenes [C1] such as VNB is appropriate, it exhibits sufficient crosslinking performance, and when a crosslinked molded article is produced using the copolymer (S1), it exhibits excellent crosslinking speed and the molded article after crosslinking shows excellent mechanical properties.

[0050] The copolymer (S1) more preferably satisfies the following formula (1c-1). 4.5 ≤ Mw × mass fraction of [C1] / 100 / molecular weight of [C1] ≤ 120 …Equation (1c-1)

[0051] The copolymer (S1) more preferably satisfies the following formula (1c-2). 4.5 ≤ Mw × mass fraction of [C1] / 100 / molecular weight of [C1] ≤ 100 …Equation (1c-2)

[0052] The weight-average molecular weight (Mw) of the copolymer (S1) can be determined as a polystyrene-converted value measured by gel permeation chromatography (GPC). Specifically, in this specification, it was determined using 3D-GPC as described in the examples below.

[0053] The copolymer (S1) has an appropriate degree of crosslinking when the above formula (1c), (1c-1), or (1c-2) is satisfied by the above formula "Mw × mass fraction of [C1] / 100 / molecular weight of [C1]". Therefore, a transmission belt with excellent mechanical properties can be manufactured using copolymer (S1).

[0054] Requirements (1-6) The complex viscosity η at frequency ω = 0.1 rad / s was obtained by linear viscoelasticity measurement (190°C) using a rheometer. * ( ω =0.1) (Pa·s) and complex viscosity η at frequency ω = 100 rad / s * ( ω =100) Ratio P[η] (Pa·s) * ( ω =0.1) / η * ( ω =100) The intrinsic viscosity [η] of the copolymer (S1) and the mass fraction of [C1] satisfy the following formula (1d). P / ([η] 2.9 ) ≤ [C1] mass fraction × 6 …Equation (1d)

[0055] Here, the complex viscosity η at frequency ω = 0.1 rad / s is given. * ( ω =0.1) And the complex viscosity η at frequency ω = 100 rad / s *( ω =100) The ratio P[η] * ( ω =0.1) / η * ( ω =100) ] represents the frequency dependence of viscosity and corresponds to the left side of equation (1d) above, P / ([η] 2.9 Although influenced by factors such as short-chain branching and molecular weight, the value tends to be higher when there are many long-chain branches.

[0056] Generally, in ethylene-α-olefin-non-conjugated polyene copolymers, the more structural units derived from the non-conjugated polyene they tend to have, the more long-chain branching they have. However, copolymer (S1) is thought to satisfy equation (1d) above because it has fewer long-chain branching units than conventionally known ethylene-α-olefin-non-conjugated polyene copolymers. The copolymer (S1) more preferably satisfies the following formula (1d-1). P / ([η] 2.9 ) ≤ [C1] Mass fraction × 5.7 …Equation (1d-1)

[0057] In this invention, the P value is determined by the ratio (η) between the complex viscosity at 0.1 rad / s and the complex viscosity at 100 rad / s, obtained by measuring under conditions of 190°C, 1.0% strain, and varying frequency using a viscoelasticity measuring device Ares (manufactured by Rheometric Scientific). * This is the calculation of the ratio.

[0058] Furthermore, the intrinsic viscosity [η] of the copolymer (S1) in requirement (1-6) refers to the value measured in decalin at 135°C. The intrinsic viscosity [η] of the copolymer (S1) is preferably 0.1 to 5.0 dL / g, more preferably 0.5 to 4.0 dL / g, even more preferably 1.0 to 3.0 dL / g, and particularly preferably 1.5 to 2.5 dL / g. The weight-average molecular weight (Mw) of the copolymer (S1) is preferably 10,000 to 600,000, more preferably 100,000 to 550,000, even more preferably 200,000 to 500,000, and particularly preferably 300,000 to 450,000.

[0059] Requirements (1-7) The complex viscosity η at frequency ω = 0.01 rad / s was obtained by linear viscoelasticity measurement (190°C) using a rheometer. * ( ω =0.01) (Pa·s) and complex viscosity η at frequency ω = 10 rad / s * ( ω =10) (Pa·s) and the apparent iodine value derived from the unconjugated polyene [C1] satisfy the following equation (1e). Log{η * ( ω =0.01)} / log{η * ( ω =10)}≦0.0753 × {Apparent iodine value derived from unconjugated polyene [C1]} + 1.42 …Equation (1e) Here, complex viscosity η * ( ω =0.01) and complex viscosity η * ( ω =10) The complex viscosity η in requirement (1-6) is * ( ω =0.1) and complex viscosity η * ( ω =100) The same method can be used to determine the other parameters, except for the measurement frequency.

[0060] Furthermore, the apparent iodine value derived from the unconjugated polyene [C1] can be calculated using the following equation (X). The apparent iodine value derived from [C1] = Mass fraction of [C1] × 253.81 / Molecular weight of [C1] ... Equation (X)

[0061] In the above formula (1e), the left side represents the shear rate dependence, which is an indicator of the amount of long-chain branching, and the right side represents an indicator of the content of unconjugated polyene [C1] that was not consumed as long-chain branching during polymerization. When the above formula (1e) is satisfied, it is preferable because the degree of long-chain branching is not too high. On the other hand, when the above formula (1e) is not satisfied, it indicates that a large proportion of the copolymerized unconjugated polyene [C1] was consumed for the formation of long-chain branching.

[0062] Requirements (1-8) The copolymer (S1) has a glass transition temperature (Tg) of -65°C or lower, preferably -70°C or lower, as measured by differential scanning calorimetry (DSC). By using copolymer (S1) with a glass transition temperature within the above range, the low-temperature characteristics of the resulting transmission belt are improved. Here, Tg is specifically determined by the method described in the examples below.

[0063] The copolymer (S1) has a Mooney viscosity ML(1+4)100°C preferably of 5 to 150, more preferably of 10 to 100, even more preferably of 20 to 50, and particularly preferably of 25 to 40.

[0064] When the Mooney viscosity ML(1+4) at 100°C is within the above range, a copolymer (S1) is obtained that exhibits excellent roll processability even with a high-hardness, oil-free formulation, as well as good post-treatment (ribbon handling properties) and superior rubber properties. Here, the Mooney viscosity ML(1+4) at 100°C is specifically determined by the method described in the examples below.

[0065] This composition may contain two or more copolymers (S1). For example, two or more copolymers (S1) with different molar ratios of ethylene [A1] / α-olefin [B1] having 4 to 20 carbon atoms, iodine value, or intrinsic viscosity [η] can be mixed and used. In particular, for (c), a method of mixing a low intrinsic viscosity component with a high intrinsic viscosity component can be used.

[0066] <Method for producing copolymer (S1)> The copolymer (S1) can be obtained by various known production methods, for example, by conventionally known production methods using a metallocene catalyst. Examples of metallocene catalysts and production methods using such catalysts can be found in, for example, International Publication No. 2015 / 122415, particularly in paragraphs

[0249] to

[0320] of said publication.

[0067] <Ethylene-propylene-nonconjugated polyene copolymer (S2)> This composition contains an ethylene-propylene-non-conjugated polyene copolymer (S2) (hereinafter also referred to as "polymer (S2)"). The copolymer (S2) has structural units derived from ethylene [A2], structural units derived from propylene, and structural units derived from a non-conjugated polyene [C2] that contain a total of two or more substructures selected from the group consisting of the following general formulas (I) and (II) in one molecule.

[0068] Examples of non-conjugated polyenes [C2] include 5-vinyl-2-norbornene (VNB), norbornadiene, 1,4-hexadiene, and dicyclopentadiene.

[0069] Due to their high availability, good crosslinking with organic peroxides, and ease of improving the heat resistance of the composition, the non-conjugated polyene [C2] preferably contains structural units derived from 5-vinyl-2-norbornene (VNB), and more preferably the non-conjugated polyene [C2] is VNB. The non-conjugated polyene [C2] may be used alone or in combination of two or more types.

[0070] The copolymer (S2) may further contain structural units derived from ethylene [A2], propylene, and non-conjugated polyene [C2], as well as structural units derived from non-conjugated polyene [CY] that contain only one substructure selected from the group consisting of the above general formulas (I) and (II) in each molecule. Examples of such non-conjugated polyenes [CY] include those similar to the non-conjugated polyenes [CX] described above. Non-conjugated polyenes [CY] may be used alone or in combination of two or more types.

[0071] If the copolymer (S2) contains constituent units derived from a non-conjugated polyene [CY], the mass fraction thereof is preferably 0 to 20% by mass, more preferably 0 to 10% by mass, and even more preferably 0.01 to 8% by mass, relative to the total constituent units of the copolymer (S2).

[0072] Each copolymer (S2) may contain at least one biomass-derived monomer (ethylene [A2], α-olefin with 4 to 20 carbon atoms [B2], unconjugated polyene [C2], unconjugated polyene [CY]).

[0073] Each copolymer (S2) may contain at least one constituent unit derived from a chemically recycled monomer.

[0074] The copolymer (S2) preferably satisfies one or more of the following requirements (2-1) to (2-4), more preferably satisfies two or more of the following requirements (2-1) to (2-4), even more preferably satisfies three or more of the following requirements (2-1) to (2-4), and particularly preferably satisfies all of the following requirements (2-1) to (2-4).

[0075] Requirements (2-1) The molar ratio [[A2] / propylene] of structural units derived from ethylene [A2] to structural units derived from propylene is 40 / 60 to 90 / 10. Copolymers (S2) with a molar ratio within this range exhibit an excellent balance between rubber elasticity at low temperatures and tensile stress at room temperature.

[0076] The lower limit of the above molar ratio [[A2] / propylene] is preferably 45 / 55, more preferably 50 / 50, even more preferably 55 / 45, and particularly preferably 60 / 40. The upper limit of the above molar ratio [[A2] / propylene] is preferably 85 / 15, more preferably 80 / 20, and even more preferably 75 / 25. The molar ratio [[A2] / propylene] is, 1 It can be measured using H-NMR spectroscopy, etc.

[0077] Requirements (2-2) The mass fraction of structural units derived from non-conjugated polyene [C2] is 0.07 to 10% by mass, with the total of structural units derived from ethylene [A2], propylene, and non-conjugated polyene [C2] being 100% by mass.

[0078] The mass fraction of structural units derived from the non-conjugated polyene [C2] is preferably 0.1 to 8.0 mass%, more preferably 0.5 to 5.0 mass%, even more preferably 1.0 to 3.0 mass%, and particularly preferably 1.2 to 2.0 mass%. When the mass fraction of structural units derived from the non-conjugated polyene [C2] is within the above range, a copolymer (S2) with sufficient crosslinkability and flexibility is obtained. The content ratio of each structural unit in the copolymer (S2) is: 13 It can be measured using C-NMR spectroscopy, etc.

[0079] Requirements (2-3) The weight-average molecular weight (Mw) of the copolymer (S2), the mass fraction of structural units derived from the non-conjugated polyene [C2] (mass fraction of [C2] (mass%)), and the molecular weight of the non-conjugated polyene [C2] (molecular weight of [C2]) satisfy the following formula (2c). 4.5 ≤ Mw × mass fraction of [C2] / 100 / molecular weight of [C2] ≤ 80 …Equation (2c)

[0080] When the copolymer (S2) satisfies the requirement (2-3), the content of the structural unit derived from the non-conjugated polyene [C2] such as VNB is appropriate, showing sufficient crosslinking performance. When a crosslinked molded body is manufactured using the copolymer (S2), it is preferable because it has excellent crosslinking speed and the molded body after crosslinking exhibits excellent mechanical properties.

[0081] The copolymer (S2) more preferably satisfies the following formula (2c-1). 4.5 ≦ Mw × mass fraction of [C2] / 100 / molecular weight of [C1] ≦ 70 … Formula (2c-1)

[0082] The copolymer (S2) even more preferably satisfies the following formula (2c-2). 4.5 ≦ Mw × mass fraction of [C2] / 100 / molecular weight of [C1] ≦ 60 … Formula (2c-2)

[0083] The weight average molecular weight (Mw) of the copolymer (S2) can be determined as a polystyrene equivalent value measured by gel permeation chromatography (GPC). In this specification, specifically, it was determined as described in the examples below using 3D-GPC.

[0084] When the “Mw × mass fraction of [C2] / 100 / molecular weight of [C2]” of the copolymer (S2) satisfies the above formula (2c), (2c-1) or (2c-2), the degree of crosslinking is appropriate, and by using this, a transmission belt excellent in mechanical properties can be manufactured.

[0085] 《Requirement (2-4)》 The complex viscosity η at a frequency ω = 0.1 rad / s obtained by linear viscoelastic measurement (190 ° C) using a rheometer * ( ω =0.1) (Pa·s) and the complex viscosity η at a frequency ω = 100 rad / s * ( ω =100) (Pa·s), and the ratio P of η * ( ω =0.1) / η *( ω =100) The intrinsic viscosity [η] of the copolymer (S2) and the mass fraction of the above [C2] satisfy the following formula (2d). P / ([η] 2.9 ) ≤ mass fraction of [C2] × 6 … Formula (2d)

[0086] Here, the complex viscosity η * ( ω =0.1) at a frequency ω = 0.1 rad / s and the complex viscosity η * ( ω​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​Furthermore, the intrinsic viscosity [η] of the copolymer (S2) in requirement (2-4) refers to the value measured in decalin at 135°C. The intrinsic viscosity [η] of the copolymer (S2) (in decalin at 135°C) is preferably 0.1 to 5.0 dL / g, more preferably 0.5 to 4.0 dL / g, and even more preferably 1.0 to 3.0 dL / g. The weight-average molecular weight (Mw) of the copolymer (S2) is preferably 1,000 to 600,000, more preferably 30,000 to 550,000, and even more preferably 50,000 to 500,000.

[0090] This composition may contain two or more copolymers (S2). For example, two or more copolymers (S2) with different (a) ethylene [A2] / propylene molar ratios, (b) iodine values, or (c) intrinsic viscosity [η] (in decalin at 135°C) can be mixed and used. In particular, for (c), a method of mixing a low intrinsic viscosity component with a high intrinsic viscosity component can be used.

[0091] The mass fraction of copolymer (S1) in relation to the total mass of copolymer (S1) and copolymer (S2) is preferably 5% by mass or more and less than 100% by mass, more preferably 20 to 90% by mass, even more preferably 40 to 80% by mass, and particularly preferably 45 to 75% by mass. The mass fraction of copolymer (S2) in relation to the total mass of copolymer (S1) and copolymer (S2) is preferably greater than 0% by mass and 95% by mass or less, more preferably 10 to 80% by mass, even more preferably 20 to 60% by mass, and particularly preferably 25 to 55% by mass. When the mass fraction of copolymer (S1) is within the above range, it is easy to obtain a composition that can form a transmission belt with excellent processability, a modulus (tensile stress) suitable for transmission belts, and excellent wear resistance.

[0092] The copolymer (S2) can be obtained by various known manufacturing methods, for example, the method described in the section on the manufacturing method of copolymer (S1) above.

[0093] <Carbon Black (B)> This composition contains carbon black (B). Carbon black (B) is a component that contributes, for example, to improving the mechanical strength, modulus, and wear resistance of the resulting (crosslinked) molded article.

[0094] Examples of carbon black (B) include SRF, GPF, FEF, MAF, HAF, ISAF, SAF, FT, and MT. The surface of the carbon black may be treated with a silane coupling agent. Examples of commercially available carbon blacks include "Asahi #55G", "Asahi #50HG", "Asahi #60G", "Asahi #60UG", "Asahi #70" (product names, manufactured by Asahi Carbon Co., Ltd.), "Seast V", and "Seast SO" (product names, manufactured by Tokai Carbon Co., Ltd.).

[0095] This composition may contain one type of carbon black (B), or it may contain two or more types of carbon black (B). The carbon black (B) content in this composition is preferably 0.1 to 200 parts by mass, more preferably 10 to 200 parts by mass, even more preferably 20 to 100 parts by mass, and particularly preferably 30 to 50 parts by mass, based on 100 parts by mass of the total amount of copolymer (S1) and copolymer (S2). This configuration is preferable from the viewpoint of the mechanical strength of the resulting (crosslinked) molded article and the processability of the composition.

[0096] <Short fiber (C)> This composition contains short fibers (C). The use of short fibers (C) improves the modulus and mechanical strength of the (crosslinked) molded article formed from this composition. Since the copolymer (S1) also exhibits excellent kneadability with short fibers (C), this composition tends to have excellent moldability.

[0097] Examples of short fibers (C) include fibers made from synthetic resins such as polyamide, polyimide, polyester, polyvinyl alcohol, rayon, polyolefin, polyarylate, polyphenylene sulfide, polyether ether ketone, polyp-phenylene benzobisoxazole, and fluorinated polymers; and natural fibers such as cotton and wood cellulose fibers. Among these, short fibers made from synthetic resins are preferred, and short fibers made from polyamide are more preferred. Short fibers (C) are usually not short fibers formed from copolymers (S1) or copolymers (S2).

[0098] Examples of polyamides include aliphatic polyamides such as polycapramide, poly-ω-aminoheptanoic acid, poly-ω-aminononanoic acid, polyundecaneamide, polyethylenediamine adipamide, polytetramethylene adipamide, polyhexamethylene adipamide, polyhexamethylene sevacamide, polyhexamethylene dodecamide, polyoctamethylene adipamide, and polydecamethylene adipamide; and aromatic polyamides (aramids) such as poly-p-phenylene terephthalamide, polymetaphenylene isophthalamide, coply-p-phenylene-3,4'-oxydiphenylene terephthalamide, polymetaxylylene adipamide, polymetaxylylene pimellamid, polymetaxylylene azeramide, poly-p-xylylene azeramide, and poly-p-xylylene decanamide.

[0099] As for the short fibers (C), from the viewpoint of further improving the tensile stress and tear strength of the resulting (crosslinked) molded article, short fibers made of aromatic polyamide, i.e., aramid short fibers, and more preferably poly(p-phenylene-terephthalamide), poly(metaphenylene-isophthalamide), and poly(p-phenylene-3,4'-oxydiphenylene-terephthalamide) short fibers, are preferred.

[0100] The average fiber length of the short fibers (C) is typically 0.1 to 50 mm, preferably 0.5 to 10 mm, more preferably 0.5 to 6 mm, even more preferably 1.0 to 5.0 mm, and particularly preferably 2.0 to 4.0 mm. The fiber diameter of the short fibers (C) is typically 0.1 to 100 μm, preferably 0.1 to 25 μm, and more preferably 1 to 20 μm.

[0101] The average fiber length of a short fiber (C) can be determined, for example, by taking photographs of the short fibers using an optical microscope, measuring the lengths of 100 randomly selected short fibers in the resulting photographs, and taking the arithmetic mean of these measurements.

[0102] The short fiber (C) may be a chopped fiber (cut fiber) type short fiber or a pulp-type short fiber having fibrils.

[0103] This composition may contain one type of short fiber (C), or it may contain two or more types of short fibers (C). The content of short fibers (C) in this composition is usually 0.1 to 100 parts by mass, preferably 0.1 to 30 parts by mass, more preferably 3 to 20 parts by mass, and even more preferably 5 to 10 parts by mass, based on 100 parts by mass of the total of copolymer (S1) and copolymer (S2). This configuration is preferable from the viewpoint of the modulus and mechanical strength of the resulting (crosslinked) molded article.

[0104] <Other ingredients> This composition may further contain at least one selected from crosslinking agents (D), vulcanization accelerators, vulcanization accelerators, crosslinking aids (E), processing aids (F), surfactants, softeners, inorganic fillers, reinforcing agents, antioxidants, surfactants, hygroscopic agents, antistatic agents, colorants, lubricants, thickeners, and other polymers (excluding copolymers (S1) and copolymers (S2)) (hereinafter also referred to as "other components"). Each of the other components may be used individually or in combination of two or more.

[0105] Crosslinking agent (D) Examples of crosslinking agents (D) include those commonly used when crosslinking rubber, such as organic peroxides, sulfur compounds, phenolic resins, hydrosilicone compounds, amino resins, quinones or their derivatives, amine compounds, azo compounds, epoxy compounds, isocyanate compounds, and quinone dioxime crosslinking agents such as p-quinone dioxime. Among these, organic peroxides and sulfur compounds are preferred.

[0106] If the composition contains a crosslinking agent (D), the amount of crosslinking agent (D) is usually 0.1 to 20 parts by mass, preferably 0.2 to 15 parts by mass, and more preferably 0.5 to 10 parts by mass, based on 100 parts by mass of the total of copolymer (S1), copolymer (S2), and other polymers (such as rubber) that require crosslinking as needed.

[0107] Examples of organic peroxides include dicumyl peroxide (DCP), di-tert-butyl peroxide, 2,5-di-(tert-butylperoxy)hexane, 2,5-dimethyl-2,5-di-(tert-butylperoxy)hexane, 2,5-dimethyl-2,5-di-(tert-butylperoxy)hexine-3, 1,3-bis(tert-butylperoxyisopropyl)benzene, 1,1-bis(tert-butylperoxy)-3,3,5-trimethylcyclohexane, n-butyl-4,4-bis(tert-butylperoxy)valerate, benzoyl peroxide, p-chlorobenzoyl peroxide, 2,4-dichlorobenzoyl peroxide, tert-butylperoxybenzoate, ert-butylperoxyisopropyl carbonate, diacetyl peroxide, lauroyl peroxide, and tert-butylcumyl peroxide.

[0108] When using an organic peroxide as the crosslinking agent (D), it is preferable to use the crosslinking aid (E), which will be described later, in combination. The amount of crosslinking aid (E) added is preferably 0.5 to 10 moles, more preferably 0.6 to 5.0 moles, and even more preferably 0.8 to 3.0 moles per mole of organic peroxide.

[0109] Examples of sulfur-based compounds include sulfur, sulfur chloride, sulfur dichloride, morpholine disulfide, alkylphenol disulfide, tetramethylthiuram disulfide, and selenium dithiocarbamate. Although sulfur is not a compound, it is conveniently classified as a sulfur-based compound in this specification.

[0110] This composition may contain a vulcanization accelerator. In particular, when a sulfur-based compound is used as the crosslinking agent (D), it is preferable to use a vulcanization accelerator in combination. Examples of vulcanization accelerators include thiazole-based vulcanization accelerators such as N-cyclohexyl-2-benzothiazole sulfenamide, N-oxydiethylene-2-benzothiazole sulfenamide, N,N'-diisopropyl-2-benzothiazole sulfenamide, 2-mercaptobenzothiazole, 2-(4-morpholinodithio)benzothiazole, 2-(2,4-dinitrophenyl)mercaptobenzothiazole, 2-(2,6-diethyl-4-morpholinothio)benzothiazole, and dibenzothiadyl disulfide; guanidine-based vulcanization accelerators such as diphenylguanidine, triphenylguanidine, and diorthotrylguanidine; and aldehydeamine-based accelerators such as acetaldehyde-aniline condensates and butyraldehyde-aniline condensates. Examples of vulcanization accelerators include: imidazoline-based vulcanization accelerators such as 2-mercaptoimidazoline; thiourea-based vulcanization accelerators such as diethylthiourea and dibutylthiourea; thiram-based vulcanization accelerators such as tetramethylthiuram monosulfide, tetramethylthiuram disulfide, tetraethylthiuram disulfide, tetrabutylthiuram disulfide, and dipentamethylenethiuram tetrasulfide; dithioate-based vulcanization accelerators such as zinc dimethyldithiocarbamate, zinc diethyldithiocarbamate, zinc dibutyldithiocarbamate, and tellurium diethyldithiocarbamate; thiourea-based vulcanization accelerators such as ethylenethiourea, N,N'-diethylthiourea, and N,N'-dibutylthiourea; and xantate-based vulcanization accelerators such as zinc dibutylxatonate.

[0111] If the composition contains a vulcanization accelerator, the amount of the vulcanization accelerator is usually 0.1 to 20 parts by mass, preferably 0.2 to 15 parts by mass, and more preferably 0.5 to 10 parts by mass, based on 100 parts by mass of the total of copolymer (S1), copolymer (S2), and other polymers (such as rubber) that require crosslinking as needed.

[0112] This composition may contain a vulcanization accelerator. In particular, when a sulfur-based compound is used as the crosslinking agent (D), it is preferable to use a vulcanization accelerator in combination.

[0113] Examples of vulcanization accelerators include zinc oxide, magnesium oxide, and zinc oxide.

[0114] If the composition contains a vulcanization accelerator, the amount of the vulcanization accelerator is usually 1 to 20 parts by mass, preferably 2 to 10 parts by mass, and more preferably 3 to 8 parts by mass, based on 100 parts by mass of the total of copolymer (S1), copolymer (S2), and other polymers (such as rubber) that require crosslinking as needed.

[0115] Crosslinking agent (E) Crosslinking aid (E) is a compound that acts as a crosslinking reaction catalyst when combined with the crosslinking agent during the crosslinking of this composition by heating.

[0116] Examples of crosslinking aids (E) include acrylic crosslinking aids such as ethylene glycol dimethacrylate and trimethylolpropane trimethacrylate; allyl crosslinking aids such as diallyl phthalate and triallyl isocyanurate; other maleimide crosslinking aids; and divinylbenzene. Among these, acrylic crosslinking aids are preferred, and ethylene glycol dimethacrylate is more preferred.

[0117] If the composition contains a crosslinking aid (E), the amount of crosslinking aid (E) is preferably 0.1 to 30 parts by mass, more preferably 0.5 to 20 parts by mass, even more preferably 0.8 to 10 parts by mass, and particularly preferably 1.0 to 5.0 parts by mass, based on 100 parts by mass of the total amount of copolymer (S1) and copolymer (S2).

[0118] Processing aid (F) As processing aids (F), a wide range of materials commonly used as processing aids in rubber can be used, such as ricinoleic acid, stearic acid, palmitic acid, lauric acid, barium stearate, zinc stearate, calcium stearate, and esters. Among these, stearic acid is preferred.

[0119] If the composition contains a processing aid (F), the amount of processing aid (F) is preferably 0.1 to 20 parts by mass, more preferably 0.3 to 5.0 parts by mass, even more preferably 0.5 to 3.0 parts by mass, and particularly preferably 0.7 to 2.0 parts by mass, based on 100 parts by mass of the total amount of copolymer (S1) and copolymer (S2).

[0120] Softener Examples of softening agents include petroleum-based softening agents such as process oil, lubricating oil, paraffin oil, liquid paraffin, petroleum asphalt, and petrolatum; coal tar-based softening agents such as coal tar; fatty oil-based softening agents such as castor oil, linseed oil, rapeseed oil, soybean oil, and coconut oil; waxes such as beeswax and carnauba wax; fatty acids or their salts such as ricinoleic acid, palmitic acid, barium stearate, and calcium stearate; naphthenic acid, pine oil, rosin or its derivatives; synthetic polymers such as terpene resins, petroleum resins, and coumarone indene resins; ester-based softening agents such as dioctyl phthalate and dioctyl adipate; and others such as microcrystalline wax, liquid polybutadiene, modified liquid polybutadiene, hydrocarbon-based synthetic lubricants, tall oil, and sub(factis). Petroleum-based softening agents are preferred, and process oils are more preferred.

[0121] If the composition contains a softening agent, the amount of softening agent is usually 2 to 100 parts by mass, preferably 5 to 100 parts by mass, more preferably 5 to 30 parts by mass, and even more preferably 10 to 20 parts by mass, based on 100 parts by mass of the total of copolymer (S1), copolymer (S2), and other polymers (elastomer, rubber, etc.) that may be added as needed.

[0122] Reinforcement agent Examples of reinforcing agents include silica, calcium carbonate, activated calcium carbonate, fine talc, and differential silicic acid. However, the carbon black (B) and inorganic fillers mentioned above are excluded. Among these, silica is preferred.

[0123] If the composition contains a reinforcing agent, the amount of the reinforcing agent is usually 0.1 to 100 parts by mass, preferably 5 to 30 parts by mass, more preferably 6 to 20 parts by mass, and even more preferably 7 to 15 parts by mass, based on 100 parts by mass of the total of copolymer (S1), copolymer (S2), and other polymers (elastomer, rubber, etc.) that may be added as needed.

[0124] Anti-aging agent (stabilizer) This composition, by containing an antioxidant (stabilizer), can extend the lifespan of the (crosslinked) molded articles formed from the composition. Examples of antioxidants include amine-based antioxidants, phenol-based antioxidants, and sulfur-based antioxidants.

[0125] Examples of amine-based antioxidants include aromatic secondary amine-based antioxidants such as phenylbutylamine and N,N-di-2-naphthyl-p-phenylenediamine. Examples of phenol-based antioxidants include dibutylhydroxytoluene and pentaerythritol tetrakis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate]. Examples of sulfur-based antioxidants include thioether-based antioxidants such as bis[2-methyl-4-(3-n-alkylthiopropionyloxy)-5-t-butylphenyl] sulfide; dithiocarbamate-based antioxidants such as dibutyldithiocarbamate nickel; and 2-mercaptobenzoylimidazole, 2-mercaptobenzoimidazole, zinc salt of 2-mercaptobenzoimidazole, dilaurylthiodipropionate, and distearylthiodipropionate.

[0126] If the composition contains an antioxidant, the amount of the antioxidant is usually 0.3 to 10 parts by mass, preferably 1 to 9 parts by mass, more preferably 3 to 8 parts by mass, and even more preferably 5 to 7 parts by mass, based on 100 parts by mass of the total of copolymer (S1), copolymer (S2), and other polymers (elastomer, rubber, etc.) that may be added as needed.

[0127] Other polymers This composition may further contain other polymers besides copolymer (S1) and copolymer (S2), such as rubber and / or elastomers. Other polymers that require crosslinking include, for example, natural rubber, isoprene rubber, butadiene rubber, styrene-butadiene rubber, chloroprene rubber, nitrile rubber, butyl rubber, acrylic rubber, silicone rubber, fluororubber, and urethane rubber.

[0128] Other polymers that do not require crosslinking include, for example, styrene-butadiene block copolymers (SBS), polystyrene-poly(ethylene-butylene)-polystyrene (SEBS), polystyrene-poly(ethylene-propylene)-polystyrene (SEPS), and other styrene-based thermoplastic elastomers (TPS), such as TPS, olefin-based thermoplastic elastomers (TPO), polyvinyl chloride-based elastomers (TPVC), ester-based thermoplastic elastomers (TPC), amide-based thermoplastic elastomers (TPA), urethane-based thermoplastic elastomers (TPU), and other thermoplastic elastomers (TPZ). If this composition contains other polymers, the content of the other polymers is usually 100 parts by mass or less, preferably 80 parts by mass or less, based on 100 parts by mass of the total of copolymer (S1) and copolymer (S2).

[0129] <Preparation of this composition> This composition can be prepared by kneading a copolymer (S1), a copolymer (S2), carbon black (B), short fibers (C), and other components at a desired temperature using a kneading machine such as a mixer, kneader, or roll.

[0130] One embodiment of this composition is prepared, for example, as follows: Copolymer (S1), copolymer (S2), carbon black (B), short fibers (C), and predetermined other components are placed in a kneader and kneaded under predetermined heating conditions (e.g., 80-200°C for 3-30 minutes) to homogenize (A kneading). In A kneading, no crosslinking agent, etc., which would crosslink copolymer (S1) and copolymer (S2) when heated to the heating temperature of A kneading, is added. After lowering the temperature of the mixture kneaded in A kneading to below the crosslinking temperature of the crosslinking agent (e.g., 130°C or below), the crosslinking agent, etc., that was not added in A kneading is added to the mixture, and it is further kneaded under predetermined heating conditions (e.g., roll temperature 30-80°C for 1-30 minutes) to homogenize (B kneading) to obtain this composition.

[0131] In the composition before the addition of the crosslinking agent (composition A), the Mooney viscosity ML(1+4) at 125°C is preferably 10 to 250, more preferably 10 to 100, even more preferably 20 to 50, and particularly preferably 30 to 45. Compositions with a Mooney viscosity within the above range exhibit good post-processing quality and possess excellent rubber properties.

[0132] [(Cross-linked) molded products, power transmission belts] A (crosslinked) molded article can be obtained from this composition. This composition can be molded by thermoforming methods such as extrusion molding, injection molding, press molding, calendering, transfer molding, and foam molding. The crosslinking temperature of the composition is usually 140°C or higher, preferably 150-220°C, and more preferably 160-200°C. Furthermore, this crosslinking reaction can be carried out in air.

[0133] In the present invention, the above-mentioned (crosslinked) molded article can be suitably used as a component of a power transmission belt. For example, this composition has high adhesive strength suitable for moldability and excellent belt processability. Furthermore, by using this composition, it is possible to manufacture a power transmission belt component with excellent rubber elasticity, abrasion resistance, heat resistance, and cold resistance.

[0134] The power transmission belt of the present invention has a (crosslinked) molded body formed from this composition. Examples of power transmission belts of the present invention include friction transmission belts such as V-belts and V-ribbed belts; interlocking transmission belts such as timing belts; and toothed belts. Examples of power transmission belts include those for automobiles, motorcycles, and general industrial machinery. Examples of V-belts include wrapped belts and raw-edge belts.

[0135] One embodiment of a power transmission belt may have, for example, an adhesive rubber portion in which a core wire is embedded, and further may have a bottom rubber portion formed on the lower surface of the adhesive rubber portion. The power transmission belt may optionally have an upper canvas formed on the adhesive rubber portion and / or a lower canvas formed below the bottom rubber portion. This composition is suitably used, for example, to form the adhesive rubber portion and / or the bottom rubber portion. Specifically, a cross-linked molded portion formed from this composition is suitably used as the adhesive rubber portion and / or the bottom rubber portion.

[0136] The core wire, which is the tensile member of the power transmission belt, extends in the longitudinal direction of the belt within the adhesive rubber portion. Examples of the core wire include polyester cords. The adhesive rubber portion surrounds and adheres to the core wire. In one embodiment, for example, the adhesive rubber portion adhered to the core wire can be formed by arranging the composition around the core wire and crosslinking it. Examples of canvas include cotton, a blend of cotton and polyester, and a blend of cotton and polyamide. [Examples]

[0137] The present invention will be described in more detail below based on examples, but the present invention is not limited in any way to these examples.

[0138] <Physical properties of copolymers> [Composition of copolymer] The molar amounts of each constituent unit of the copolymer are: 1 The intensity was determined by measuring it using an H-NMR spectrometer. Details of the measurement conditions are described in International Publication No. 2015 / 122415. The mass fraction (mass%) of each constituent unit of the copolymer is: 13 The copolymer was determined by measurement using 1C-NMR. The measurement was performed using an ECX400P nuclear magnetic resonance spectrometer (JEOL), with a measurement temperature of 120°C, a measurement solvent of orthodichlorobenzene / deuterated benzene = 4 / 1, and 8000 cumulative cycles. 13 The spectrum was obtained by measuring the 1C-NMR spectrum.

[0139] [Iodine value] The apparent iodine value derived from the unconjugated polyene [C1] (hereinafter also referred to as the "[C1] iodine value") was calculated based on the above formula (X).

[0140] [Mooney Viscosity] Mooney viscosity (ML(1+4)100℃) was measured using a Mooney viscometer (SMV202 model, Shimadzu Corporation) in accordance with JIS K6300 (1994).

[0141] [B value] Using o-dichlorobenzene-d4 / benzene-d6 (4 / 1 [v / v]) as the measurement solvent, at a measurement temperature of 120°C, 13 The 13C-NMR spectrum (100 MHz, JEOL ECX400P) was measured and calculated based on the above formula (1a).

[0142] [Number of branching points BrNo] Using a 3D high-temperature GPC system, model PL-GPC220 (manufactured by Polymer Laboratories), the absolute molecular weight distribution was determined, and simultaneously, the intrinsic viscosity was determined using a viscometer. The main measurement conditions are as follows: Detector: Differential refractometer / GPC device built-in 2-angle light scattering photometer PD2040 type (manufactured by Precison Detectors) Bridge-type viscometer PL-BV400 (manufactured by Polymer Laboratories) Column: TSKgel GMHHR-H(S)HT x 2 + TSKgel + GMHHR-M(S) x 1 (each with an inner diameter of 7.8mmφ and a length of 300mm) Temperature: 140℃ Mobile phase: 1,2,4-trichlorobenzene (containing 0.025% BHT) Injection volume: 0.5mL Sample concentration: Ca 1.0 mg / mL Sample filtration: Filtered using a 1.0 μm pore size sintered filter. The dn / dc value required to determine the absolute molecular weight was determined for each sample using the dn / dc value (derivative value of refractive index n with respect to concentration c) of standard polystyrene (molecular weight 190,000), which is 0.053, and the response intensity of a differential refractometer per unit injection mass. The long-chain branching parameter g' for each eluted component is determined from the relationship between the intrinsic viscosity obtained from the viscometer and the absolute molecular weight obtained from the light scattering photometer. i This was calculated from equation (v-1).

[0143]

number

[0144] Here, [η] = KM v The relationship v = 0.725 was applied. This equation is called the Mark-Houwink-Sakurada equation, where K is the solvent constant, M is the absolute molecular weight, and v represents the morphology of the polymer chain at the measurement temperature in the measured solvent (i.e., the shape of the molecule, the degree of bending, etc., and how the molecule spreads). Furthermore, the average values ​​for each value were calculated as g' using the following formulas (v-2), (v-3), and (v-4). Note that the Trendline, assuming only short-chain branching, was determined for each sample.

[0145]

number

[0146] Furthermore, g' w The number of branching points per molecular chain, BrNo, was calculated using the Zimm-Stockmayer equation (v-5). g is the long-chain branching parameter obtained from the radius of inertia Rg, and the following simple correlation is made between it and g' obtained from the intrinsic viscosity. g=g' (1 / ε) (ε(structure factor)=0.5~1.5) Various values ​​have been proposed for ε in the equation depending on the shape of the numerator. Here, we performed the calculation assuming ε = 1 (i.e., g' = g).

[0147]

number

[0148] [Intrinsic viscosity [η]] The intrinsic viscosity [η] (dl / g) of the copolymer was measured using a fully automatic intrinsic viscometer manufactured by Rigosha Co., Ltd., at a temperature of 135°C and using decalin as the measurement solvent.

[0149] [Weight average molecular weight (Mw)] The weight-average molecular weight (Mw) of the copolymer was determined using a 3D-high-temperature GPC instrument (PL-GPC220, Polymer Laboratories) under the same measurement conditions as for the branching point number (BrNo).

[0150] [complex viscosity η] * and p-value] Using an Ares viscoelasticity measuring device (manufactured by Rheometric Scientific) as the rheometer, the complex viscosity η was measured at a frequency ω = 0.01 rad / s under conditions of 190°C and 1.0% strain. * ( ω =0.01) Complex viscosity η at frequency ω = 0.1 rad / s * ( ω =0.1) Complex viscosity η at frequency ω = 10 rad / s * ( ω =10) and complex viscosity η at frequency ω = 100 rad / s * ( ω =100) (All measurements were taken in Pa·s.)

[0151] Furthermore, from the results obtained, η * ( ω =0.1) and η * ( ω =100) The ratio of complex viscosity to (η) * The p-value (η) is the ratio. * ( ω =0.1) / η * ( ω =100) ) was calculated.

[0152] [Glass transition temperature (Tg)] The glass transition temperature (Tg) of the copolymer was determined by DSC measurement under the following conditions. Using a differential scanning calorimeter (RDC220, SII Corporation), approximately 10 mg of the sample was heated from 30°C to 200°C at a heating rate of 50°C / min under a nitrogen atmosphere and held at that temperature for 10 minutes. It was then cooled to -100°C at a cooling rate of 10°C / min, held at that temperature for 5 minutes, and then heated again to 200°C at a heating rate of 10°C / min.

[0153] The glass transition temperature (Tg) is detected during the second heating cycle when the DSC curve bends due to the change in specific heat, causing the baseline to shift. The temperature at the intersection of the tangent to the baseline below this bend and the tangent to the point where the slope is maximum in the bent portion is defined as the glass transition temperature (Tg).

[0154] [Ethylene-α-olefin-non-conjugated polyene copolymer (A1)] In the following examples, the copolymer (A1) obtained in Production Example 1 was used.

[0155] <Manufacturing Example 1> The polymerization of ethylene, 1-butene, and 5-vinyl-2-norbornene (VNB) was carried out continuously at 95°C using a 300 L polymerizer equipped with stirring blades. Hexane (feed rate: 32.4 L / h) was used as the polymerization solvent and was continuously supplied to the polymerizer at a rate of 5.2 kg / h for ethylene, 24.0 kg / h for 1-butene, 1070 g / h for VNB, and 17 NL / h for hydrogen.

[0156] While maintaining a polymerization pressure of 1.6 MPaG and a polymerization temperature of 95°C, di(p-tolyl)methylene(cyclopentadienyl)(octamethyloctahydrodibenzofluorenyl)zirconium dichloride was continuously supplied to the polymerizer as the main catalyst at a feed rate of 0.0154 mmol / h. In addition, (C6H5)3CB(C6F5)4 was continuously supplied to the polymerizer as a co-catalyst at a feed rate of 0.077 mmol / h, and triisobutylaluminum (TIBA) was continuously supplied to the polymerizer as an organoaluminum compound at a feed rate of 30 mmol / h.

[0157] In this way, a solution containing 20% ​​by mass of ethylene-1-butene-VNB copolymer formed from ethylene, 1-butene, and VNB was obtained. A small amount of methanol was added to the polymerization reaction solution withdrawn from the bottom of the polymerizer to stop the polymerization reaction, and the ethylene-1-butene-VNB copolymer was separated from the solvent by steam stripping, and then dried under reduced pressure at 80°C overnight.

[0158] Through the above procedure, ethylene-1-butene-VNB copolymer (S1) was obtained at a rate of 7.2 kg per hour. The physical properties of copolymer (S1) were measured by the method described above. The results are shown in Table 1.

[0159] [Table 1]

[0160] [Ethylene-propylene-non-conjugated polyene copolymer (S2)] In the following examples, copolymers (S2-1) and (S2-2) obtained in Production Examples 2 and 3 below were used.

[0161] <Manufacturing Example 2> The polymerization of ethylene, propylene, and 5-vinyl-2-norbornene (VNB) was carried out continuously at 87°C using a 300 L polymerizer equipped with stirring blades. Hexane (feed rate: 58.3 L / h) was used as the polymerization solvent and was continuously supplied to the polymerizer at a rate of 6.6 kg / h for ethylene, 9.3 kg / h for propylene, 340 g / h for VNB, and 18 NL / h for hydrogen.

[0162] While maintaining a polymerization pressure of 1.6 MPaG and a polymerization temperature of 87°C, di(p-tolyl)methylene(cyclopentadienyl)(octamethyloctahydrodibenzofluorenyl)zirconium dichloride was continuously supplied to the polymerizer as the main catalyst at a feed rate of 0.030 mmol / h. In addition, (C6H5)3CB(C6F5)4 was continuously supplied to the polymerizer as a co-catalyst at a feed rate of 0.150 mmol / h, and triisobutylaluminum (TIBA) was continuously supplied as an organoaluminum compound at a feed rate of 4.5 mmol / h.

[0163] In this way, a solution containing 20% ​​by mass of an ethylene-propylene-VNB copolymer formed from ethylene, propylene, and VNB was obtained. A small amount of methanol was added to the polymerization reaction solution withdrawn from the bottom of the polymerizer to stop the polymerization reaction, and the ethylene-propylene-VNB copolymer was separated from the solvent by steam stripping. After that, it was dried under reduced pressure at 80°C overnight.

[0164] Through the above procedure, ethylene-propylene-VNB copolymer (S2-1) was obtained at a rate of 7.8 kg per hour. The physical properties of copolymer (S2-1) were measured by the method described above. The results are shown in Table 2.

[0165] <Manufacturing Example 3> An ethylene-propylene-VNB copolymer (S2-2) was obtained in accordance with the description of [Production Example 2: Copolymer (S2-1)] in Japanese Patent Publication No. 2024-032012. The physical properties of copolymer (S2-2) were measured by the method described above. The results are shown in Table 2.

[0166] [Table 2]

[0167] [Example 1] Using a MIXTRON BB MIXER (manufactured by Kobe Steel, Ltd., BB-2 type, volume 1.7L, rotor 2WH), 50 parts by mass of copolymer (S1), 25 parts by mass of copolymer (S2-1), 50 parts by mass of copolymer (S2-2), 1 part by mass of stearic acid as a processing aid (F), 5 parts by mass of ZnO#1 (two types of zinc oxide, JIS K-1410 (2006)) as a vulcanization accelerator, 2 parts by mass of Irganox 1010 as an antioxidant 1, 4 parts by mass of Sandant MB as an antioxidant 2, 40 parts by mass of Asahi #70 as carbon black (B), 10 parts by mass of ULTRASIL VN3 (silica) as a reinforcing agent, 15 parts by mass of Diana Process Oil PW-380 as a softening agent, and 8 parts by mass of aramid short fibers (C) were mixed and kneaded to obtain formulation 1.

[0168] The mixing conditions for preparing formulation 1 were a rotor speed of 40 rpm and a floating weight pressure of 3 kg / cm². 2 The mixing time was 5 minutes, and the mixing discharge temperature was 144°C. The Mooney viscosity ML(1+4) at 125°C of formulation 1 was measured using a Mooney viscometer (SMV202 model, Shimadzu Corporation) in accordance with JIS K6300 (1994).

[0169] Next, after confirming that the temperature of formulation 1 reached 40°C, formulation 1 was kneaded using a 6-inch roll to add 6.8 parts by mass of DCP-40C as a crosslinking agent (D) and 2 parts by mass of Sunester EG as a crosslinking aid (E) to obtain formulation 2.

[0170] The kneading conditions for preparing formulation 2 were as follows: roll temperature (front roll / rear roll = 50°C / 50°C), roll peripheral speed (front roll / rear roll = 18 rpm / 15 rpm), and roll gap (3 mm). The mixture was kneaded for 8 minutes and then dispensed in small batches to obtain formulation 2.

[0171] Compound 2 was pressed using a press molding machine at 170°C for 15 minutes to produce a 2 mm thick crosslinked sheet. The obtained crosslinked sheet was subjected to hardness tests, tensile tests, and DIN abrasion tests, as described below.

[0172] [Example 2, Comparative Example 1] The procedure was the same as in Example 1, except that it was based on the composition and vulcanization system described in Table 3.

[0173] <Physical properties of compositions, etc.> [Adhesion (Probe Tack Test)] The probe tack test was performed using a probe tack tester as follows. The above compound 2 was separated into sheets to obtain an uncrosslinked sheet with a thickness of 1 mm. This uncrosslinked sheet was used as a test specimen and fixed to a probe tack tester. Next, the bottom surface of a cylindrical probe (5 mm diameter stainless steel probe) was brought close to one side of the test specimen at a constant speed and brought into contact with it. Then, the cylindrical probe was pressed into the test specimen, and once a certain load was applied to the specimen, it was held for a certain period of time. After that, the cylindrical probe was immediately peeled off the test specimen at a constant speed, and this process was carried out while measuring the test force.

[0174] The above process was carried out under the following conditions. Approach speed: 120mm / min. Pressure: 100g Pressurization time: 20s Peeling speed: 120mm / min. Temperature for placing the probe and test specimen (uncrosslinked sheet): 23°C In the curve representing the relationship between test force and time measured during the above process, the peak value (gf) at which the indentation force is the minimum value was determined (corresponding to the maximum load required to detach the cylindrical probe from the test specimen) when the indentation force is considered positive. Adhesion was evaluated by the magnitude of the absolute value of the peak value.

[0175] [Rolling properties] When preparing composition 2 using the conditions and method described in Example 1, the wrapability and surface condition of the composition were observed when it was wound onto a 6-inch roll (front roll 18 rpm, back roll 15 rpm, roll gap 1 mm) heated to 50°C. The following evaluation criteria were used for evaluation. Evaluation Criteria 3: The roll has rubber wrapped around it, and the surface is glossy. 2: The rubber wraps around the roll, but surface roughness is observed. 1: The rubber does not wrap around the roller, making mixing impossible.

[0176] [Vulcanization rate test] Using an MDR2000P (manufactured by ALPHATECHNOLOGIES) as the measuring device, the torque change obtained under constant temperature and constant shear rate conditions in compound 2 was measured at a temperature of 170°C and for a time of 30 minutes. The difference between the minimum torque S'min and the maximum torque S'max (S'max-S'min), the time it took for the torque of the sample to increase by 1 [dNm] after reaching the minimum torque S'min (TS1), the time it took for the torque of the sample to reach 90% of the value when the minimum torque S'min is set to 0% and the maximum torque S'max is set to 100% (tc90), and the MCR (Maximum Curing Rate, which indicates the maximum slope of the vulcanization curve) [dNm / min] were determined. A smaller tc90 indicates a higher vulcanization rate (crosslinking rate).

[0177] [Hardness Test (Durometer-A)] The flat portions of the above 2mm thick crosslinked sheets were stacked to form a 12mm thick sheet, and its hardness (Duro-A) was measured according to JIS K6253.

[0178] [Tensile test: Modulus, tensile stress at fracture, tensile elongation at fracture] The crosslinked sheet with a thickness of 2 mm was punched out to produce dumbbell test pieces of Type 3 described in JIS K6251 (1993). Using these test pieces, a tensile test was conducted in accordance with the method specified in Paragraph 3 of JIS K6251 under the conditions of a measurement temperature of 25°C and a tensile speed of 500 mm / min, and the tensile stress (5% modulus (M5)), tensile stress (10% modulus (M10)), tensile stress (25% modulus (M25)), tensile stress (50% modulus (M50)), tensile stress (100% modulus (M100)), tensile break point stress (TB), and tensile break point elongation (EB) when the elongation rate was 5%, 10%, 25%, 50%, and 100% were measured.

[0179] [DIN Abrasion Test (DIN Abrasion Amount)] The crosslinked sheet with a thickness of 2 mm was used to produce disc-shaped test pieces with a diameter of 16.0 ± 0.2 mm and a thickness of 6 mm or more in accordance with JIS-K6264-2:2005. For this test piece, using a DIN abrasion tester, a drum with a diameter of 150.0 ± 0.2 mm and a length of 500 mm was rotated at 40 revolutions per minute, and the abrasion amount (DIN abrasion amount: unit mm 3 ) was measured when the load was 1 kgf and the abrasion distance was 40.0 ± 0.2 m.

[0180]

Table 3

[0181] As the materials described in Table 3 above, those described in Table 4 below were used.

[0182]

Table 4

Claims

1. It has a structural unit derived from ethylene [A1], a structural unit derived from an α-olefin [B1] having 4 to 20 carbon atoms, and a structural unit derived from a non-conjugated polyene [C1] containing a total of two or more substructures selected from the group consisting of the following general formulas (I) and (II) in one molecule. The structural unit derived from the α-olefin [B1] having 4 to 20 carbon atoms includes a structural unit derived from 1-butene. The structural units derived from the non-conjugated polyene [C1] include structural units derived from 5-vinyl-2-norbornene in the ethylene-α-olefin-non-conjugated polyene copolymer (S1), An ethylene-propylene-non-conjugated polyene copolymer (S2) having structural units derived from ethylene [A2], structural units derived from propylene, and structural units derived from a non-conjugated polyene [C2] containing a total of two or more substructures selected from the group consisting of the following general formulas (I) and (II) in one molecule, Carbon black (B) and, A composition for power transmission belts containing short fibers (C). 【Chemistry 1】

2. The transmission belt composition according to claim 1, wherein the copolymer (S1) satisfies the following requirements (1-1) to (1-4): Requirement (1-1): The molar ratio [[A1] / [B1]] of structural units derived from ethylene [A1] to structural units derived from α-olefins [B1] having 4 to 20 carbon atoms is 40 / 60 to 90 / 10; Requirements (1-2): The content of structural units derived from non-conjugated polyenes [C1] is 0.1 to 6.0 mol%, with the total of structural units derived from ethylene [A1], α-olefins having 4 to 20 carbon atoms [B1], and non-conjugated polyenes [C1] being 100 mol%; Requirements (1-3): The B value, expressed by the following formula (1a), is 1.20 or greater; B value = ([EX] + 2[Y]) / [2 × [E] × ([X] + [Y])] ... Equation (1a) [Here, [E], [X], and [Y] represent the mole fractions of structural units derived from ethylene [A1], α-olefins having 4 to 20 carbon atoms [B1], and non-conjugated polyenes [C1], respectively, and [EX] represents the ethylene [A1]-α-olefins having 4 to 20 carbon atoms [B1] dyad chain fraction.] Requirements (1-4): The number of branching points per molecular chain, BrNo, obtained using 3D-GPC, satisfies the following formula (1b). BrNo≧0.5...Formula (1b)

3. The transmission belt composition according to claim 1, wherein the copolymer (S1) satisfies one or more of the following requirements (1-5) to (1-8): Requirements (1-5): The weight-average molecular weight (Mw) of the copolymer (S1), the mass fraction of structural units derived from the non-conjugated polyene [C1] (mass fraction of [C1] (mass%)), and the molecular weight of the non-conjugated polyene [C1] (molecular weight of [C1]) satisfy the following formula (1c); 4.5 ≤ Mw × mass fraction of [C1] / 100 / molecular weight of [C1] ≤ 150 ... Equation (1c) Requirement (1-6): The ratio P [η * / η ( ] of the complex viscosity η * (Pa·s) at a frequency ω = 0.1 rad / s and the complex viscosity η ( (Pa·s) at a frequency ω = 100 rad / s obtained by linear viscoelastic measurement (190 °C) using a rheometer, the intrinsic viscosity [η] of the copolymer (S1), and the mass fraction of [C1] satisfy the following formula (1d); * ( ω =0.1) (Pa·s) and the complex viscosity η * * ( ω =100) (Pa·s) and the ratio P [η * / η ( * ( ω =0.1) / η * * ( ω =100) 〕 and the intrinsic viscosity [η] of the copolymer (S1) and the mass fraction of [C1] satisfy the following formula (1d); P / ([η] 2.9 ) ≤ Mass fraction of [C1] × 6 …Equation (1d) Requirements (1-7): Complex viscosity η at frequency ω = 0.01 rad / s, obtained by linear viscoelastic measurement (190°C) using a rheometer. * ( ω =0.01) (Pa·s) and the complex viscosity η at frequency ω = 10 rad / s * ( ω =10) (Pa·s) and the apparent iodine value derived from the unconjugated polyene [C1] satisfy the following equation (1e): Log{η} * ( ω =0.01) } / Log{η * ( ω =10) } ≤ 0.0753 × {Apparent iodine value derived from unconjugated polyene [C1]} + 1.42 …Equation (1e) Requirements (1-8): The glass transition temperature (Tg) measured by differential scanning calorimetry (DSC) is -65°C or lower.

4. The transmission belt composition according to claim 1, wherein the mass fraction of copolymer (S1) in relation to the total mass of copolymer (S1) and copolymer (S2) is 5% by mass or more and less than 100% by mass.

5. The transmission belt composition according to claim 1, wherein the copolymer (S2) includes a structural unit derived from 5-vinyl-2-norbornene as a structural unit derived from a non-conjugated polyene [C2].

6. The transmission belt composition according to claim 1, wherein the content of the short fibers (C) is 0.1 to 100 parts by mass with respect to 100 parts by mass of the total of the copolymer (S1) and the copolymer (S2).

7. The transmission belt composition according to claim 1, wherein the short fiber (C) is an aramid short fiber.

8. The transmission belt composition according to claim 1, wherein the Mooney viscosity ML(1+4) at 100°C of the copolymer (S1) is 5 to 150.

9. The transmission belt composition according to claim 1, further comprising an organic peroxide as a crosslinking agent (D).

10. The transmission belt composition according to claim 1, further containing 0.1 to 20 parts by mass of a processing aid (F) per 100 parts by mass of the copolymer (S1) and the copolymer (S2).

11. The transmission belt composition according to claim 1, further comprising a crosslinking aid (E).

12. A molded article formed from the transmission belt composition according to any one of claims 1 to 11.

13. A transmission belt having the molded body described in claim 12.

14. A crosslinked molded article formed from the transmission belt composition according to any one of claims 1 to 11.

15. A transmission belt having a crosslinked molded body as described in claim 14.

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