JP2020094185A - Composition for transmission belt - Google Patents

Abstract

To provide a composition for transmission belt high in adhesive force and excellent in moldability.SOLUTION: There is provided a composition for transmission belt containing 100 pts.mass of an ethylene α-olefin non-conjugated polyene copolymer having structural units derived from ethylene [A1], α-olefin having 4 to 20 carbon atoms [A2], and non-conjugated polyene [A3] and satisfying (1) to (3), and 0.1 to 200 pts.mass of carbon black. (1) a molar ratio of the structural unit derived from ethylene [A1] and the structural unit derived from α-olefin having 4 to 20 carbon atoms [A2] [[A1]/[A2]] is 40/60 to 90/10. (2) percentage content of the structural unit derived from the non-conjugated polyene [A3] is 0.1 to 6.0 mol% based on 100 mol% of total of structural units derived from [A1], [A2] and [A3]. (3) B value is 1.20 or more. B value=([EX]+2[Y])/[2×[E]×([X]+[Y])]SELECTED DRAWING: None

Description

The present invention relates to a composition for power transmission belts.

Transmission belts are widely used for automobiles, motorcycles, and general industrial machines. The transmission belt is required to have high rubber elasticity and wear resistance. Chloroprene rubber is commonly used to produce power transmission belts that meet the above properties. Here, in order to improve heat resistance and cold resistance and to reduce weight, it has been considered to use ethylene/propylene/non-conjugated polyene copolymer rubber instead of chloroprene rubber (for example, Patent Documents 1 to 2). reference).

JP, 2001-310951, A JP, 2012-215212, A

According to the study of the present inventors, when an ethylene/propylene/non-conjugated polyene copolymer is used, the adhesive force (tack) between the sheets formed from the composition for a power transmission belt containing the copolymer. Is insufficient, and therefore molding process tends to be difficult. An object of the present invention is to provide a composition for a power transmission belt, which has a high adhesive force and therefore has excellent moldability.

The inventors of the present invention have conducted extensive studies to solve the above-mentioned problems, and have found that the above-mentioned problems can be solved by a composition for a transmission belt having the following constitution, and have completed the present invention. That is, the present invention relates to, for example, the following [1] to [9].

[1] having a structural unit derived from ethylene [A1], a structural unit derived from an α-olefin [A2] having 4 to 20 carbon atoms, and a structural unit derived from a non-conjugated polyene [A3], For a transmission belt containing 100 parts by mass of an ethylene/α-olefin/non-conjugated polyene copolymer (A) satisfying the requirements (1) to (3) and 0.1 to 200 parts by mass of carbon black (B). Composition.
(1) The molar ratio [[A1]/[A2]] of the structural unit derived from ethylene [A1] and the structural unit derived from the α-olefin [A2] having 4 to 20 carbon atoms is 40/60 or more. 90/10,
(2) The content ratio of the structural units derived from the non-conjugated polyene [A3] is 0.1 to 6.0 with the total of the structural units derived from [A1], [A2] and [A3] being 100 mol %. Mol%,
(3) The B value represented by the following formula (i) is 1.20 or more.
B value=([EX]+2[Y])/[2×[E]×([X]+[Y])]...(i)
[Here, [E], [X], and [Y] are moles of structural units derived from ethylene [A1], α-olefin [A2] having 4 to 20 carbon atoms, and non-conjugated polyene [A3], respectively. Shows the fraction, and [EX] represents the ethylene [A1]-C4 to C20 α-olefin [A2] dyad chain fraction. ]
[2] For the power transmission belt according to [1], wherein the structural unit derived from the α-olefin [A2] having 4 to 20 carbon atoms in the copolymer (A) includes a structural unit derived from 1-butene. Composition.
[3] The above [1], which further contains short fibers (C), and the content of the short fibers (C) is 0.1 to 100 parts by mass with respect to 100 parts by mass of the copolymer (A). Alternatively, the composition for a power transmission belt according to [2].
[4] The composition for a power transmission belt according to the above [3], wherein the short fibers (C) are aramid fibers.
[5] The composition for a power transmission belt according to any one of [1] to [4], wherein the ethylene/α-olefin/non-conjugated polyene copolymer (A) further satisfies the following requirement (4).
(4) Mooney viscosity ML _{(1+4) at} 100° C. is 5 to 150 at 100° C.
[6] The composition for a power transmission belt according to any one of the above [1] to [5], further containing a crosslinking aid having two or more ethylenic double bonds.
[7] A molded product formed from the composition for a power transmission belt according to any one of [1] to [6].
[8] A crosslinked molded article formed from the composition for a power transmission belt according to any one of [1] to [6].
[9] A transmission belt having the molded article according to [7] or the crosslinked molded article according to [8].

According to the present invention, it is possible to provide a composition for a power transmission belt, which has a high adhesive force and is therefore excellent in molding processability.

The present invention will be described in detail.
[Composition for power transmission belt]
The composition for a power transmission belt of the present invention (hereinafter, also referred to as “the composition of the present invention”) comprises an ethylene/α-olefin/non-conjugated polyene copolymer (A) and a carbon black (B) described below. contains. The composition of the present invention preferably further contains short fibers (C).

<Ethylene/α-olefin/non-conjugated polyene copolymer (A)>
The ethylene/α-olefin/non-conjugated polyene copolymer (A) includes a structural unit derived from ethylene [A1], a structural unit derived from α-olefin [A2] having 4 to 20 carbon atoms, and a non-conjugated polyene. It has a structural unit derived from [A3] and satisfies the following requirements (1) to (3). Hereinafter, the above-mentioned (A) is also referred to as "component (A)". In one embodiment, the component (A) preferably satisfies the requirement (4) or (4′) described later.

The component (A) includes a structural unit derived from ethylene [A1], a structural unit derived from at least one C4 to C20 α-olefin [A2], and at least one non-conjugated polyene [. A3] and a structural unit derived from A3].
(1) The molar ratio [[A1]/[A2]] of the structural unit derived from ethylene [A1] and the structural unit derived from the α-olefin [A2] having 4 to 20 carbon atoms is 40/60 or more. It is 90/10.
(2) The content ratio of the structural units derived from the non-conjugated polyene [A3] is 0.1 to 6.0 with the total of the structural units derived from [A1], [A2] and [A3] being 100 mol %. Mol %.
(3) The B value represented by the following formula (i) is 1.20 or more.
B value=([EX]+2[Y])/[2×[E]×([X]+[Y])]...(i)
Here, [E], [X], and [Y] are each a molar amount of a structural unit derived from ethylene [A1], an α-olefin [A2] having 4 to 20 carbon atoms, and a non-conjugated polyene [A3]. And [EX] represents ethylene [A1]-C4-20 α-olefin [A2] dyad chain fraction.

Examples of the α-olefin [A2] having 4 to 20 carbon atoms include 1-butene, 1-pentene, 1-hexene, 1-heptene, 1-octene, 1-nonene, 1-decene and 1-nonadecene. -Linear α-olefins such as eicosene; side-chain-containing α-olefins such as 4-methyl-1-pentene, 9-methyl-1-decene, 11-methyl-1-dodecene and 12-ethyl-1-tetradecene Is mentioned. Among these, α-olefins having 4 to 10 carbon atoms are preferable, 1-butene, 1-hexene and 1-octene are more preferable, and 1-butene is further preferable.

The α-olefin [A2] having 4 to 20 carbon atoms can be used alone or in combination of two or more kinds.
The ethylene/propylene/non-conjugated polyene copolymer in which the α-olefin is propylene has a low adhesive force between the obtained compositions, and therefore a molded article and a crosslinked molded article of the composition (hereinafter, these are collectively referred to as “ Moldability into a (crosslinked) molded body) tends to be low. Further, this copolymer tends to have low kneadability with the short fiber (C).

On the other hand, in the present invention, at least the component (A) is used as the rubber component. Since the component (A) has a structural unit derived from the α-olefin [A2] having 4 to 20 carbon atoms, it is presumed that the obtained compositions have higher adhesiveness, and therefore the composition has a higher adhesive force. , (Crosslinked) molded article, especially for a power transmission belt. Further, the component (A) is also excellent in kneading properties with the short fibers (C).

Examples of the non-conjugated polyene [A3] include 1,4-hexadiene, 1,6-octadiene, 2-methyl-1,5-hexadiene, 6-methyl-1,5-heptadiene, 7-methyl-1,6. -Chain nonconjugated dienes such as octadiene; cyclohexadiene, dicyclopentadiene, methyltetrahydroindene, 5-vinyl-2-norbornene, 5-ethylidene-2-norbornene, 5-methylene-2-norbornene, 5-isopropylidene- Cyclic non-conjugated dienes such as 2-norbornene and 6-chloromethyl-5-isopropenyl-2-norbornene; 2,3-diisopropylidene-5-norbornene, 2-ethylidene-3-isopropylidene-5-norbornene, 2 -Propenyl-2,5-norbornadiene, 1,3,7-octatriene, 1,4,9-decatriene, 4,8-dimethyl-1,4,8-decatriene, 4-ethylidene-8-methyl-1, Trienes such as 7-nonadiene may be mentioned. Among these, chain nonconjugated dienes such as 1,4-hexadiene, cyclic nonconjugated dienes such as 5-ethylidene-2-norbornene and 5-vinyl-2-norbornene are preferable, and cyclic nonconjugated dienes are more preferable. -Ethylidene-2-norbornene and 5-vinyl-2-norbornene are more preferred.

The non-conjugated polyene [A3] can be used alone or in combination of two or more kinds.
Examples of the component (A) include ethylene/1-butene/1,4-hexadiene copolymer, ethylene/1-pentene/1,4-hexadiene copolymer, ethylene/1-hexene/1,4-hexadiene. Copolymer, ethylene/1-heptene/1,4-hexadiene copolymer, ethylene/1-octene/1,4-hexadiene copolymer, ethylene/1-nonene/1,4-hexadiene copolymer, Ethylene/1-decene/1,4-hexadiene copolymer, ethylene/1-butene/1-octene/1,4-hexadiene copolymer, ethylene/1-butene/5-ethylidene-2-norbornene copolymer , Ethylene/1-pentene/5-ethylidene-2-norbornene copolymer, ethylene/1-hexene/5-ethylidene-2-norbornene copolymer, ethylene/1-heptene-5-ethylidene-2-norbornene copolymer Polymer, ethylene/1-octene/5-ethylidene-2-norbornene copolymer, ethylene/1-nonene/5-ethylidene-2-norbornene copolymer, ethylene/1-decene-5-ethylidene-2-norbornene Copolymer, ethylene/1-butene/1-octene/5-ethylidene-2-norbornene copolymer, ethylene/1-butene/5-ethylidene-2-norbornene-5-vinyl-2-norbornene copolymer, Ethylene-1-pentene-5-ethylidene-2-norbornene-5-vinyl-2-norbornene copolymer, ethylene/1-hexene-5-ethylidene-2-norbornene-5-vinyl-2-norbornene copolymer, Ethylene/1-heptene-5-ethylidene-2-norbornene-5-vinyl-2-norbornene copolymer, ethylene/1-octene-5-ethylidene-2-norbornene-5-vinyl-2-norbornene copolymer , Ethylene/1-nonene/5-ethylidene-2-norbornene/5-vinyl-2-norbornene copolymer, ethylene/1-decene-5-ethylidene-2-norbornene/5-vinyl-2-norbornene copolymer And ethylene/1-butene/1-octene/5-ethylidene-2-norbornene-5-vinyl-2-norbornene copolymer.

<<Requirement (1)>>
The component (A) is (1) a molar ratio [[A1]/[A2]] of a structural unit derived from ethylene [A1] and a structural unit derived from an α-olefin [A2] having 4 to 20 carbon atoms. Is 40/60 to 90/10. The component (A) having a molar ratio within the above range has an excellent balance between rubber elasticity at low temperature and tensile strength at room temperature.

The lower limit of [A1]/[A2] is preferably 45/55, more preferably 50/50, and particularly preferably 55/45. The upper limit of [A1]/[A2] is preferably 80/20, more preferably 75/25, and even more preferably 70/30.

<<Requirement (2)>>
In the component (A), (2) the content ratio of the structural unit derived from the non-conjugated polyene [A3] is the same as the structural unit derived from the [A1], the structural unit derived from the [A2], and the [A3]. It is 0.1 to 6.0 mol% when the total of the derived structural units is 100 mol %. The component (A) whose content ratio is within the above range has sufficient crosslinkability and flexibility.

The lower limit of the content ratio of the structural unit derived from [A3] is preferably 0.5 mol %. The upper limit of the content ratio of the structural unit derived from [A3] is preferably 4.0 mol%, more preferably 3.5 mol%, and further preferably 3.0 mol%.

<<Requirement (3)>>
In the component (A), the B value represented by the formula (i) (3) is 1.20 or more, preferably 1.20 to 1.80, and more preferably 1.22 to 1.40.

An ethylene/α-olefin/non-conjugated polyene copolymer having a B value of less than 1.20 may have a large compression set at low temperature and may not be excellent in balance between rubber elasticity at low temperature and tensile strength at room temperature. There is. The component (A) having a B value of 1.20 or more has high alternation of the monomer units constituting the copolymer and low crystallinity, and thus the processability of the obtained composition is improved.

The B value is an index showing the randomness of the distribution of copolymerized monomer chains in the copolymer, and [E], [X], [Y], and [EX] in the formula (i) are ¹³ The C-NMR spectrum can be measured and determined based on the reports of JC Randall [Macromolecules, 15, 353 (1982)] and J. Ray [Macromolecules, 10, 773 (1977)]. On the other hand, in (1) and (2) above, a structural unit derived from ethylene [A1], a structural unit derived from α-olefin [A2] having 4 to 20 carbon atoms, and a structure derived from non-conjugated polyene [A3]. The molar amount of the unit can be determined by measuring the intensity with a ¹ H-NMR spectrometer.

<<Requirement (4)>>
As for the component (A), (4) the Mooney viscosity ML _{(1+4) at} 100° C. is preferably 5 to 150, more preferably 5 to 100, and further preferably 5 to 50. The component (A) having a Mooney viscosity in the above range has good processability and fluidity, exhibits good post-treatment quality (ribbon handling property), and has excellent rubber physical properties.

<<Requirement (4')>>
As for the component (A), the Mooney viscosity ML ₍₁₊₄₎ 125° C. at (4′) 125° C. is preferably 3 to 100, more preferably 3 to 70, and further preferably 3 to 30. The component (A) having a Mooney viscosity in the above range has good processability and fluidity, exhibits good post-treatment quality (ribbon handling property), and has excellent rubber physical properties.

The composition of the present invention may contain one type of component (A) or may contain two or more types of component (A).
The content ratio of the component (A) in the composition of the present invention is usually 20% by mass or more, preferably 30 to 90% by mass.

<<Method for producing component (A)>>
The component (A) can be obtained by a conventionally known production method using a metallocene catalyst. As the metallocene catalyst and the production method using the catalyst, for example, the examples described in WO 2015/122415, particularly paragraphs [0249] to [0320] of the publication can be adopted.

In particular,
A transition metal compound (a) represented by the following formula (a):
At least one compound selected from the organometallic compound (b-1), the organoaluminumoxy compound (b-2), and the compound (b-3) which reacts with the transition metal compound (a) to form an ion pair ( Component (A) is obtained by copolymerizing ethylene [A1], α-olefin having 4 to 20 carbon atoms [A2] and non-conjugated polyene [A3] in the presence of an olefin polymerization catalyst containing b). Can be obtained.

The above formula (a) will be described.
M is a titanium atom, a zirconium atom or a hafnium atom.
Each R is independently a substituted aryl group obtained by substituting one or more hydrogen atoms of the aryl group with an electron-donating group having a Hammett's rule substituent constant σ of −0.2 or less. When the substituted aryl group has a plurality of electron donating groups, each electron donating group may be the same or different.

Q is the same or different combination selected from a halogen atom, a hydrocarbon group having 1 to 20 carbon atoms, an anion ligand and a neutral ligand capable of coordinating with a lone pair of electrons, and preferably a halogen atom. ..

j is an integer of 1 to 4, and is preferably 2.
Examples of the aryl group in R include a phenyl group, a 1-naphthyl group, a 2-naphthyl group, an anthracenyl group, a phenanthrenyl group, a tetracenyl group, a chrysenyl group, a pyrenyl group, an indenyl group, an azulenyl group, a pyrrolyl group, a pyridyl group and a furanyl group. Group and a thiophenyl group are mentioned, and a phenyl group is preferable.

The electron donating group having a Hammett's rule substituent constant σ of −0.2 or less is defined and exemplified as follows. Hammett's rule is an empirical rule proposed by L. P. Hammett in 1935 to quantitatively discuss the effect of substituents on the reaction or equilibrium of benzene derivatives, which is widely accepted today. Substituent constants obtained by the Hammett's rule include σp when substituted at the para position of the benzene ring and σm when substituted at the meta position, and these values can be found in many general literatures. For example, the article by Hansch and Taft [Chem. Rev., 91, 165 (1991)] gives a detailed description of a very wide range of substituents. However, the values of σp and σm described in these documents may be slightly different depending on the documents even if they are the same substituents. In order to avoid confusion caused by such a situation in this specification, as far as possible substituents are given, Hansch and Taft [Chem. Rev., 91, 165 (1991)], Table 1 (168- The values given on page 175) are defined as the Hammett's rule substituent constants σp and σm. In the present specification, the electron-donating group having a Hammett's rule substituent constant σ of −0.2 or less means that when the electron-donating group is substituted at the para position (4th position) of the phenyl group, σp is −0. .2 or less, and when substituted at the meta position (3 position) of the phenyl group, .sigma.m is an electron donating group of -0.2 or less. When the electron donating group is substituted at the ortho position (2 position) of the phenyl group or at any position of the aryl group other than the phenyl group, σp is -0.2 or less. It is an electron-donating group.

Examples of the electron-donating group having a Hammett's rule substituent constant σp or σm of −0.2 or less include p-amino group (4-amino group), p-dimethylamino group (4-dimethylamino group), p -Nitrogen-containing groups such as diethylamino group (4-diethylamino group) and m-diethylamino group (3-diethylamino group); oxygen such as p-methoxy group (4-methoxy group) and p-ethoxy group (4-ethoxy group) Group-containing groups: tertiary hydrocarbon groups such as pt-butyl group (4-t-butyl group); silicon-containing groups such as p-trimethylsiloxy group (4-trimethylsiloxy group).

It is preferable that each R is independently a substituted phenyl group containing a group selected from a nitrogen-containing group and an oxygen-containing group as the electron-donating group.
The substituted aryl group is a hydrocarbon group having 1 to 20 carbon atoms, a silicon-containing group, a nitrogen-containing group, an oxygen-containing group, a halogen other than an electron-donating group having a Hammett's rule substituent constant σ of −0.2 or less. It may have another substituent selected from an atom and a halogen-containing group. When the substituted aryl group has a plurality of other substituents, the respective other substituents may be the same or different.

The sum of Hammett's rule substituent constants σ of Hammett's rule substituent constant σ contained in one substituted aryl group of −0.2 or less and other substituents is −0.15 or less. Preferably. Examples of such a substituted aryl group include m,p-dimethoxyphenyl group (3,4-dimethoxyphenyl group), p-(dimethylamino)-m-methoxyphenyl group (4-(dimethylamino)-3- Methoxyphenyl group), p-(dimethylamino)-m-methylphenyl group (4-(dimethylamino)-3-methylphenyl group), p-methoxy-m-methylphenyl group (4-methoxy-3-methylphenyl) Group) and p-methoxy-m,m-dimethylphenyl group (4-methoxy-3,5-dimethylphenyl group).

Examples of the halogen atom in Q include fluorine, chlorine, bromine and iodine; examples of the hydrocarbon group having 1 to 20 carbon atoms include an alkyl group having 1 to 10 carbon atoms and a cycloalkyl group having 3 to 10 carbon atoms. Examples include anionic ligands such as an alkoxy group, aryloxy group, carboxylate group, and sulfonate group; examples of neutral ligands that can coordinate with a lone electron pair include trimethylphosphine, triethylphosphine, and triphenyl. Examples thereof include organic phosphorus compounds such as phosphine and diphenylmethylphosphine, and ether compounds such as tetrahydrofuran, diethyl ether, dioxane and 1,2-dimethoxyethane.

Examples of the transition metal compound (a) include [bis(4-methoxyphenyl)methylene(η ⁵ -cyclopentadienyl)(η ⁵ -2,3,6,7-tetramethylfluorenyl)] hafnium dichloride. Is mentioned.

Examples of the organometallic compound (b-1) (excluding the organoaluminum oxy compound (b-2)) include, for example, trialkylaluminum such as trimethylaluminum, triethylaluminum, triisobutylaluminum, tri-n-octylaluminum, trialkylaluminum, trialkylaluminum and the like. Organic aluminum compounds such as cycloalkyl aluminum, isobutyl aluminum dichloride, diethyl aluminum chloride, ethyl aluminum dichloride, ethyl aluminum sesquichloride, methyl aluminum dichloride, dimethyl aluminum chloride, and diisobutyl aluminum hydride are included.

Examples of the organoaluminum oxy compound (b-2) include conventionally known aluminoxanes.
Examples of the compound (b-3) which reacts with the transition metal compound (a) to form an ion pair include, for example, JP-A-1-501950, JP-A-1-502036, and JP-A-3-179005. JP-A-3-179006, JP-A-3-207703, JP-A-3-207704, USP-5321106, International Publication No. 2015/122415, and other Lewis acids, ionic compounds, Examples include borane compounds and carborane compounds.

The olefin polymerization catalyst may contain a carrier (c), if necessary. The carrier (c) is an inorganic compound or an organic compound, and is a granular or fine particle solid. Of these, the inorganic compound is preferably a porous oxide, an inorganic halide, clay, a clay mineral, or an ion-exchange layered compound.

The polymerization method may be any of liquid phase polymerization methods such as solution (dissolution) polymerization and suspension polymerization, or gas phase polymerization methods. The polymerization temperature is usually -50 to +200°C, preferably 0 to 200°C. The polymerization pressure is usually normal pressure to 10 MPa gauge pressure, preferably normal pressure to 5 MPa gauge pressure. The polymerization reaction can be carried out by any of a batch system, a semi-continuous system and a continuous system. It is also possible to carry out the polymerization in two or more stages under different reaction conditions.

<Carbon black (B)>
Carbon black (B) is a component that contributes to, for example, improvement of mechanical strength, modulus, and abrasion resistance of the obtained (crosslinked) molded body.

Examples of the carbon black (B) include SRF, GPF, FEF, MAF, HAF, ISAF, SAF, FT and MT. The surface of 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” (trade name, manufactured by Asahi Carbon Co., Ltd.), “SEAST V”, “ "Seast SO" (trade name, manufactured by Tokai Carbon Co., Ltd.).

The composition of the present invention may contain one kind of carbon black (B) or may contain two or more kinds of carbon black (B).
The content of the carbon black (B) in the composition of the present invention is 0.1 to 200 parts by mass, preferably 10 to 200 parts by mass, more preferably 20 to 100 parts by mass with respect to 100 parts by mass of the component (A). It is 100 parts by mass. Such an embodiment is preferable from the viewpoint of mechanical strength of the obtained (crosslinked) molded product and processability of the composition of the present invention.

<Short fiber (C)>
The composition of the present invention preferably further contains short fibers (C). By using the short fibers (C), the modulus and mechanical strength of the (crosslinked) molded product formed from the composition can be improved. Since the component (A) is also excellent in kneading properties with the short fibers (C), the composition of the present invention tends to have excellent moldability even if it contains the short fibers (C).

Examples of the short fibers (C) include synthetic resins such as polyamide, polyimide, polyester, polyvinyl alcohol, rayon, polyolefin, polyarylate, polyphenylene sulfide, polyether ether ketone, polyparaphenylene benzobisoxazole, and fluoropolymer. Fibers: natural fibers such as cotton and wood cellulose fibers can be mentioned. Among these, short fibers made of synthetic resin are preferable, and short fibers made of polyamide are more preferable. The short fibers (C) are usually not short fibers formed from the component (A).

Examples of the polyamide include polycapramide, poly-ω-aminoheptanoic acid, poly-ω-aminononanoic acid, polyundecane amide, polyethylenediamine adipamide, polytetramethylene adipamide, polyhexamethylene adipamide, and polyhexamethylene. Aliphatic polyamides such as sebacamide, polyhexamethylene dodecamide, polyoctamethylene adipamide, polydecamethylene adipamide; polyparaphenylene terephthalamide (trade name "Kevlar", manufactured by Toray DuPont), poly Metaphenylene isophthalamide, copolyparaphenylene-3,4'-oxydiphenylene terephthalamide, polymetaxylylene adipamide, polymetaxylylene pimeramide, polymetaxylylene azelamide, polyparaxylylene azamide, poly An aromatic polyamide (aramid) such as paraxylylene decanamide can be used.

The short fibers (C) are preferably short fibers made of aromatic polyamide, that is, aramid short fibers, from the viewpoint of further improving the tensile stress and tear strength of the obtained (crosslinked) molded product, and polyparaphenylene terephthalate. More preferred are ramid staple fibers, polymetaphenylene isophthalamide staple fibers, and copolyparaphenylene-3,4'-oxydiphenylene terephthalamide staple fibers.

The average fiber length of the short fibers (C) is usually 0.1 to 50 mm, preferably 0.5 to 10 mm, more preferably 0.5 to 6 mm. The fiber diameter of the short fibers (C) is usually 0.1 to 100 μm, preferably 0.1 to 25 μm, more preferably 1 to 20 μm.

The average fiber length of the short fibers (C) is obtained by, for example, taking a photograph of the short fibers with an optical microscope, measuring the lengths of 100 randomly selected short fibers in the obtained photograph, and calculating the arithmetic mean thereof. Can be obtained by doing.

The short fibers (C) may be chopped fiber (cut fiber) short fibers or pulp-like short fibers having fibrils.
The composition of the present invention may contain one type of short fibers (C) or may contain two or more types of short fibers (C).

The content of the short fibers (C) in the composition of the present invention is usually 0.1 to 100 parts by mass, preferably 0.1 to 30 parts by mass, more preferably 100 parts by mass of the component (A). It is 3 to 20 parts by mass. Such an embodiment is preferable from the viewpoint of the modulus and mechanical strength of the obtained (crosslinked) molded product.

<Other ingredients>
The composition of the present invention preferably further contains a crosslinking agent. The composition of the present invention is selected from a crosslinking aid, a softening agent, an inorganic filler, a reinforcing agent, an antiaging agent, a processing aid, an activator, a hygroscopic agent, an antistatic agent, a colorant, a lubricant and a thickener. At least one kind can be further contained. The composition of the present invention may further contain a polymer other than the component (A), for example, an elastomer and/or a rubber. Each of the components described below may be used alone or in combination of two or more.

<<Crosslinking agent>>
Examples of the cross-linking agent include cross-linking agents generally used in cross-linking rubber, for example, organic peroxides, sulfur compounds, phenol resins, hydrosilicone compounds, amino resins, quinones or derivatives thereof, Examples thereof include amine compounds, azo compounds, epoxy compounds, and isocyanate compounds. Among these, organic peroxides and sulfur compounds are preferable.

Examples of the organic peroxide include dicumyl peroxide, 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)hexyne-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-butyl peroxybenzoate, tert-butyl peroxyisopropyl carbonate, diacetyl peroxide, lauroyl peroxide, and tert-butyl cumyl peroxide.

In the composition of the present invention, when an organic peroxide is used as a cross-linking agent, the content of the organic peroxide is the component (A) and other polymers (rubber, etc.) that need to be cross-linked and are blended as necessary. Is generally 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.

When an organic peroxide is used as the crosslinking agent, it is preferable to use a crosslinking auxiliary together. In this case, the composition of the present invention further containing a crosslinking aid may be used, and the composition may be mixed with an organic peroxide before the crosslinking step to perform the crosslinking step.

Examples of the crosslinking assistant include sulfur; quinonedioxime-based crosslinking assistants such as p-quinonedioxime; crosslinking assistants having two or more ethylenic double bonds; maleimide-based crosslinking assistants; zinc oxide (for example, , ZnO#1, zinc oxide type 2 (JIS standard (K-1410), manufactured by Hakusui Tech), magnesium oxide, zinc oxide (for example, "META-Z102" (trade name; manufactured by Inoue Lime Industry Co., Ltd.), etc. Examples thereof include metal oxides such as zinc), and a crosslinking aid having two or more ethylenic double bonds is preferable.

The number of ethylenic double bonds in the crosslinking aid having two or more ethylenic double bonds is preferably 2 to 6, more preferably 2 to 4. It is considered that, by using the crosslinking aid, for example, a network can be favorably formed between the copolymer (A) and the short fibers (C). Examples of the cross-linking aid having two or more ethylenic double bonds include (meth)acrylic cross-linking aids such as ethylene glycol di(meth)acrylate and trimethylolpropane tri(meth)acrylate; diallyl phthalate and tri Allyl-based crosslinking aids such as allyl isocyanurate; vinyl-based crosslinking aids such as divinylbenzene. Among these, (meth)acrylic crosslinking aids are preferable, and ethylene glycol dimethacrylate is more preferable.

When the composition of the present invention contains a crosslinking aid, the content of the crosslinking aid is usually 0.5 to 10 mol, preferably 0.5 to 7 mol, relative to 1 mol of the organic peroxide. It is more preferably 1 to 5 mol.

When a sulfur compound is used as the crosslinking agent, specific examples thereof include sulfur, sulfur chloride, sulfur dichloride, morpholine disulfide, alkylphenol disulfide, tetramethylthiuram disulfide, and selenium dithiocarbamate.

In the composition of the present invention, when a sulfur-based compound is used as a crosslinking agent, the content of the sulfur-based compound is the sum of the component (A) and other polymer (rubber, etc.) required to be crosslinked and blended. It is usually 0.3 to 10 parts by mass, preferably 0.5 to 7.0 parts by mass, and more preferably 0.7 to 5.0 parts by mass with respect to 100 parts by mass.

When a sulfur compound is used as a crosslinking agent, it is preferable to use a vulcanization accelerator together. Examples of the vulcanization accelerator include N-cyclohexyl-2-benzothiazolesulfenamide, N-oxydiethylene-2-benzothiazolesulfenamide, N,N′-diisopropyl-2-benzothiazolesulfenamide, 2 -Mercaptobenzothiazole, 2-(4-morpholinodithio) benzothiazole), 2-(2,4-dinitrophenyl)mercaptobenzothiazole, 2-(2,6-diethyl-4-morpholinothio)benzothiazole, Thiazole-based vulcanization accelerators such as dibenzothiazyl disulfide; Guanidine-based vulcanization accelerators such as diphenylguanidine, triphenylguanidine, and diorsotolylguanidine; Aldehydeamine-based agents such as acetaldehyde/aniline condensates and butyraldehyde/aniline condensates Vulcanization accelerator; Imidazoline vulcanization accelerator such as 2-mercaptoimidazoline; Thiourea vulcanization accelerator such as diethylthiourea and dibutylthiourea; Tetramethylthiuram monosulfide, tetramethylthiuram disulfide, tetraethylthiuram disulfide, tetrabutylthiuram Thiuram-based vulcanization accelerators such as disulfide and dipentamethylene thiuram tetrasulfide; Dithioate-based vulcanization accelerators such as zinc dimethyldithiocarbamate, zinc diethyldithiocarbamate, zinc dibutyldithiocarbamate and tellurium diethyldithiocarbamate; ethylenethiourea ( For example, Sancera 22C (trade name; manufactured by Sanshin Chemical Industry Co., Ltd.), thiourea-based vulcanization accelerators such as N,N'-diethylthiourea, N,N'-dibutylthiourea, and zanthate-based such as zinc dibutylxatate. Vulcanization accelerator; Others include zinc white.

When the composition of the present invention contains a vulcanization accelerator, the content of the vulcanization accelerator is 100 in total of the component (A) and other polymer (rubber, etc.) that needs to be crosslinked and is blended as necessary. The amount 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 with respect to parts by mass.

The vulcanization aid can be preferably used when the cross-linking agent is a sulfur-based compound, and examples thereof include zinc oxide (for example, ZnO#1 and zinc oxide two types, manufactured by Hakusuitec Co., Ltd.), magnesium oxide, and zinc white (for example, , “META-Z102” (trade name; manufactured by Inoue Lime Industry Co., Ltd.) and the like).

When the composition of the present invention contains a vulcanization aid, the content of the vulcanization aid is 100 in total of the component (A) and other polymer (rubber or the like) that is required to be crosslinked. It is usually 1 to 20 parts by mass with respect to parts by mass.

《Softener》
Examples of the softening agent 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; castor oil, linseed oil, rapeseed oil, large oil Fatty oil softeners such as soybean oil and coconut oil; waxes such as beeswax and carnauba wax; fatty acids or salts thereof such as ricinoleic acid, palmitic acid, stearic acid, barium stearate, calcium stearate; naphthenic acid, pine oil, rosin Or derivatives thereof; synthetic polymer substances such as terpene resin, petroleum resin, coumarone indene resin; ester softeners such as dioctyl phthalate and dioctyl adipate; other, microcrystalline wax, liquid polybutadiene, modified liquid polybutadiene, hydrocarbon synthesis Lubricating oil, tall oil, and sub (factice) are mentioned, petroleum-based softeners are preferable, and process oils are more preferable.

When the composition of the present invention contains a softening agent, the content of the softening agent is 100 parts by mass of the total of the component (A) and other polymer (elastomer, rubber, etc.) to be blended as necessary. It is usually 2 to 100 parts by mass, preferably 5 to 100 parts by mass.

<<Inorganic filler>>
Examples of the inorganic filler include light calcium carbonate, heavy calcium carbonate, talc and clay. Among these, ground calcium carbonate is preferable.

When the composition of the present invention contains an inorganic filler, the content of the inorganic filler is 100 parts by mass with respect to a total of 100 parts by weight of the component (A) and other polymer (elastomer, rubber, etc.) to be blended as necessary. The amount is usually 2 to 50 parts by mass, preferably 5 to 50 parts by mass.

<Reinforcing agent>
Examples of the reinforcing agent include silica, calcium carbonate, activated calcium carbonate, fine powder talc, and differential silicic acid, except the carbon black (B) described above.

When the composition of the present invention contains a reinforcing agent, the content of the reinforcing agent is 100 parts by mass with respect to the total of 100 parts by mass of the component (A) and other polymers (elastomer, rubber, etc.) to be blended as necessary. It is usually 0.1 to 100 parts by mass, preferably 5 to 30 parts by mass.

<<Anti-aging agent (stabilizer)>>
When the composition of the present invention contains an antioxidant (stabilizer), the life of a (crosslinked) molded product formed from the composition can be extended. Examples of the antiaging agent include an amine antiaging agent, a phenol antiaging agent, and a sulfur antiaging agent.

Examples of the amine anti-aging agent include aromatic secondary amine anti-aging agents such as phenylbutylamine and N,N-di-2-naphthyl-p-phenylenediamine. Examples of the phenol anti-aging agent include dibutyl hydroxytoluene 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; nickel dibutyldithiocarbamate and the like. Dithiocarbamate anti-aging agents; 2-mercaptobenzoylimidazole, 2-mercaptobenzimidazole, zinc salt of 2-mercaptobenzimidazole, dilaurylthiodipropionate, distearylthiodipropionate.

When the composition of the present invention contains an anti-aging agent, the content of the anti-aging agent is 100 parts by mass with respect to the total amount of the component (A) and other polymer (elastomer, rubber, etc.) which is optionally blended. Therefore, it is usually 0.3 to 10 parts by mass, preferably 0.5 to 7.0 parts by mass.

<Processing aid>
As the processing aid, those generally blended with rubber as the processing aid can be widely used. Examples of processing aids include ricinoleic acid, stearic acid, palmitic acid, lauric acid, barium stearate, zinc stearate, calcium stearate, and esters. Of these, stearic acid is preferred.

When the composition of the present invention contains a processing aid, the content of the processing aid is 100 parts by mass with respect to the total of 100 parts by weight of the component (A) and other polymer (elastomer, rubber, etc.) to be blended as necessary. Therefore, it is usually 10 parts by mass or less, and preferably 8.0 parts by mass or less.

<<Activator>>
Examples of the activator include amines such as di-n-butylamine, dicyclohexylamine, and monoeranolamine; diethylene glycol, polyethylene glycol, lecithin, triaryl meritolate, aliphatic carboxylic acid or aromatic carboxylic acid zinc compounds, and the like. Activators; zinc peroxide preparations; ktadecyl trimethyl ammonium bromide, synthetic hydrotalcite, special quaternary ammonium compounds.

When the composition of the present invention contains an activator, the content of the activator is 100 parts by mass of the component (A) and other polymers (elastomer, rubber, etc.) optionally blended, It is usually 0.2 to 10 parts by mass, preferably 0.3 to 5 parts by mass.

<Hygroscopic agent>
Examples of the hygroscopic agent include calcium oxide, silica gel, sodium sulfate, molecular sieves, zeolite, and white carbon.
When the composition of the present invention contains a hygroscopic agent, the content of the hygroscopic agent is 100 parts by mass with respect to a total of 100 parts by mass of the component (A) and other polymer (elastomer, rubber, etc.) to be blended as necessary. Usually, it is 0.5 to 15 parts by mass, preferably 1.0 to 12 parts by mass.

《Other polymers》
The composition of the present invention may further contain a polymer other than the component (A).
Examples of other polymers that need to be crosslinked include rubbers such as natural rubber, isoprene rubber, butadiene rubber, styrene-butadiene rubber, chloroprene rubber, nitrile rubber, butyl rubber, acrylic rubber, silicone rubber, fluororubber and urethane rubber. Be done.

Other polymers that do not require cross-linking include, for example, block copolymers of styrene and butadiene (SBS), polystyrene-poly(ethylene-butylene)-polystyrene (SEBS), polystyrene-poly(ethylene-propylene)-polystyrene ( Styrene-based thermoplastic elastomer (TPS) such as SEPS), olefin-based thermoplastic elastomer (TPO), vinyl chloride-based elastomer (TPVC), ester-based thermoplastic elastomer (TPC), amide-based thermoplastic elastomer (TPA), urethane-based heat Examples of the elastomer include a thermoplastic elastomer (TPU) and other thermoplastic elastomers (TPZ).
When the composition of the present invention contains another polymer, the content of the other polymer is usually 100 parts by mass or less, preferably 80 parts by mass or less, relative to 100 parts by mass of the component (A).

<Preparation of composition>
The composition of the present invention comprises the component (A), the carbon black (B), the short fibers (C) optionally blended, and other components, for example, a kneader such as a mixer, a kneader or a roll. It can be prepared by kneading with a desired temperature.

One embodiment of the composition of the present invention is prepared, for example, as follows. The component (A), the carbon black (B), and optionally the short fibers (C), and other predetermined components are charged into a kneading machine and subjected to predetermined heating conditions (for example, 3 at 80 to 200° C.). Knead for ~ 30 minutes) to homogenize (A kneading). In the A kneading, the component (A) is crosslinked when heated to the heating temperature of the A kneading, and no crosslinking agent or the like is added. The temperature of the mixture kneaded in the A kneading is then lowered to below the crosslinking temperature of the cross-linking agent (for example, 130° C. or less), and then the cross-linking agent and the like not added in the A kneading are added to the mixture to give a predetermined amount. The composition of the present invention can be obtained by further kneading under heating conditions (for example, roll temperature 30 to 80° C. for 1 to 30 minutes) to homogenize (B kneading).

The composition of the present invention has a Mooney viscosity ML _{(1+4) at} 125° C. of usually 10 to 250, preferably 10 to 100, and more preferably 10 in the composition (A kneading) before the addition of the crosslinking agent. ~50. The composition having a Mooney viscosity in the above range exhibits good post-treatment quality and excellent rubber physical properties.

[(Crosslinked) molded product, power transmission belt]
A (crosslinked) molded body can be obtained from the composition of the present invention. The composition of the present invention can be molded by a thermoforming method such as extrusion molding, injection molding, press molding, calender molding, transfer molding or foam molding. In the present invention, the crosslinking temperature of the composition is usually 140°C or higher, preferably 150 to 220°C, more preferably 160 to 200°C. Moreover, this crosslinking reaction can be performed in air.

In the present invention, the (crosslinked) molded body can be preferably used as a constituent member of a transmission belt. For example, the composition of the present invention has high tackiness suitable for molding processability and is excellent in belt processability. Further, by using the composition of the present invention, it is possible to manufacture a constituent member of a power transmission belt which is excellent in high rubber elasticity, wear resistance, heat resistance and cold resistance.

The power transmission belt of the present invention has a (crosslinked) molded body formed from the composition of the present invention.
Examples of the power transmission belt of the present invention include friction power transmission belts such as V belts and V ribbed belts; meshing power transmission belts such as timing belts. The transmission belt is, for example, an automobile transmission belt, a motorcycle transmission belt, or a general industrial machine transmission belt. Examples of the V belt include a wrapped belt and a low edge belt.

One embodiment of the power transmission belt has, for example, an adhesive rubber portion in which a core wire is embedded, and can further have a bottom rubber portion formed on a lower surface of the adhesive rubber portion. The power transmission belt may have an upper canvas formed on the adhesive rubber portion and/or a lower canvas formed under the bottom rubber portion, if necessary. The composition of the present invention is suitably used, for example, to form an adhesive rubber part and/or a bottom rubber part. Specifically, as the adhesive rubber part and/or the bottom rubber part, a cross-linked molded part formed from the composition of the present invention is preferably used.

The core wire, which is a tensile member of the power transmission belt, extends in the longitudinal direction of the belt in the adhesive rubber portion. Examples of the core wire include a polyester cord. The adhesive rubber portion surrounds the core wire and is bonded to the core wire. In one embodiment, for example, the composition of the present invention can be arranged around the core wire and crosslinked to form an adhesive rubber portion bonded to the core wire. The canvas includes, for example, cotton, a blend of cotton and polyester, and a blend of cotton and polyamide.

Hereinafter, the present invention will be described in more detail based on examples, but the present invention is not limited to these examples. Unless otherwise specified, "parts" means "parts by mass".
[Physical properties of ethylene/α-olefin/non-conjugated polyene copolymer]
<Molar amount of structural unit derived from ethylene, structural unit derived from α-olefin, and structural unit derived from non-conjugated polyene>
The molar amount was determined by measuring the intensity with a ¹ H-NMR spectrometer. Details of the measurement conditions are described in International Publication No. 2015/122415.

<Moonie viscosity>
The Mooney viscosity (ML ₍₁₊₄₎ 100° C., 125° C.) was measured according to JIS K6300 (1994) using a Mooney viscometer (SMV202 type manufactured by Shimadzu Corporation).

<B value>
¹³ C-NMR spectrum (100 MHz, ECX400P manufactured by JEOL Ltd.) was measured at a measurement temperature of 120° C. using o-dichlorobenzene-d ₄ /benzene-d ₆ (4/1 [v/v]) as a measurement solvent. Was calculated based on the following formula (i).
B value=([EX]+2[Y])/[2×[E]×([X]+[Y])]...(i)
Here, [E], [X], and [Y] are each a molar amount of a structural unit derived from ethylene [A1], an α-olefin [A2] having 4 to 20 carbon atoms, and a non-conjugated polyene [A3]. And [EX] represents ethylene [A1]-C4-20 α-olefin [A2] dyad chain fraction.

[Ethylene/α-olefin/non-conjugated polyene copolymer]
An ethylene/1-butene/5-ethylidene-2-norbornene (ENB) copolymer having the following physical properties was obtained according to the description of [Synthesis Example C1] in WO 2015/122415. Hereinafter, this is described as "EBDM-1".
The constitution and physical properties of EBDM-1 are as follows.
Structural unit derived from ethylene: 67.7 mol%
Structural unit derived from 1-butene: 30.0 mol%
Structural unit derived from ENB: 2.3 mol%
Mooney viscosity ML ₍₁₊₄₎ 100℃: 30
Mooney viscosity ML ₍₁₊₄₎ 125℃:22
B value: 1.3

[Example 1]
Using MIXTRON BB MIXER (manufactured by Kobe Steel, Ltd., BB-2 type, volume 1.7 L, rotor 2WH), with respect to 100 parts of EBDM-1, ZnO#1/zinc oxide type 2 as a crosslinking aid ( 5 parts of JIS (K-1410)), 1 part of stearic acid as a processing aid, 40 parts of Asahi #60UG as carbon black, 10 parts of silica VN3 as silica, and Sandant MB (2-mercapto) as an antioxidant. Benzimidazole) 4 parts, Irganox 1010 (pentaerythritol tetrakis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate]) as an antiaging agent, and Diana Process Oil as a softening agent. PW-380 (paraffin-based process oil) was blended in an amount of 10 parts and then kneaded to obtain a blend 1.

The kneading conditions at the time of preparing the blend 1 were such that the rotor rotation speed was 40 rpm, the floating weight pressure was 3 kg/cm ² , the kneading time was 5 minutes, and the kneading discharge temperature was 144° C.
The Mooney viscosity ML ₍₁₊₄₎ 125° C. of the formulation 1 was measured using a Mooney viscometer (SMV202 type manufactured by Shimadzu Corporation) according to JIS K6300 (1994).

Then, after confirming that the temperature of the compound 1 reached 40° C., 6.8 Kyakumir DCP-40C (40% by mass dicumyl peroxide) as a crosslinking agent was added to the compound 1 using a 6-inch roll. Part 2 was added and kneaded to obtain a blend 2.

The kneading conditions at the time of preparing the blend 2 were as follows: roll temperature: front roll/back roll=50° C./50° C., roll peripheral speed: front roll/back roll=18 rpm/15 rpm, roll gap: 3 mm, kneading time: 8 minutes And dispensed to obtain a blend 2.

The compound 2 was pressed at 170° C. for 15 minutes using a press molding machine to prepare a crosslinked sheet having a thickness of 2 mm. The obtained crosslinked sheet was subjected to a hardness test, a tensile test, a heat aging resistance test and a Gehman twisting test which will be described later.

The compound 2 was subjected to a press treatment at 170° C. for 20 minutes using a press molding machine in which a cylindrical mold was set, to prepare a right cylindrical test piece having a thickness of 12.7 mm and a diameter of 29 mm. Then, a test piece for measuring compression set (CS) was obtained.

[Examples 2-3, Comparative Examples 1-3]
The procedure was as in Example 1 except that it was based on the composition and cure system listed in Table 2.
The materials used in the examples and comparative examples are shown in Table 1 below.

[specific gravity]
1 g of the raw material polymer or compound 1 (A kneading) was cut out to prepare a test piece. The test piece was attached to an automatic hydrometer (M-1 type manufactured by Toyo Seiki Seisaku-sho, Ltd.) under an atmosphere of 25° C., and the specific gravity was measured from the difference in mass in air and pure water. In Table 2, raw polymer refers to chloroprene rubber, 2060M or EBDM-1 (raw polymer), and compound refers to formulation 1.

[Probe tack test]
The probe tack was measured for Formulation 1 using TAC-II manufactured by RHESCA in accordance with JIS Z3284. The conditions were a temperature of 25° C., Immersion speed: 120 mm/min, Preload: 600 gf, Test speed: 120 mm/min, and Press time: 60 s.

[Adhesion between compounds]
The compound 1 (A kneading) was pressed with a 50 ton press molding machine at 190° C. for 10 minutes to prepare a sheet having a thickness of 2 mm. The two sheets were stuck together and lightly pressed by hand. The situations when the two laminated sheets were peeled off by hand were classified as follows.

<Evaluation>
⊚: The base material is destroyed without peeling even if it is peeled off by hand.
◯: It is difficult to peel off even if I try to peel it off by hand, but it peels off on the adhesive surface.
Δ: When trying to peel it, it feels pressure on the hand, but peels off.
X: When trying to peel off, almost no pressure is felt on the hand, and peeling occurs.

[Hardness test (Durometer-A)]
The flat portion of the crosslinked sheet having a thickness of 2 mm was overlapped to form a sheet having a thickness of 12 mm, and the hardness (JIS-A) was measured according to JIS K6253.

[Tensile test: modulus, tensile stress at break, tensile elongation at break]
The crosslinked sheet having a thickness of 2 mm was punched out to produce a No. 3 type dumbbell test piece described in JIS K6251 (1993), and the test piece was used for measurement according to the method specified in Clause 3 of JIS K6251. A tensile test was carried out at a temperature of 25° C. and a tensile speed of 500 mm/min. The tensile stress (25% modulus (M25)), the tensile stress at break (TB), and the tensile elongation at break (at 25% elongation) ( EB) was measured.

[Compression set test]
Regarding the compression set (CS) measurement test piece, the compression set after the treatment at −20° C. for 22 hours or after the treatment at 180° C. for 70 hours was measured according to JIS K6262 (1997). It is desirable that the compression set is small.

[Heat resistance test (heat aging test)]
The crosslinked sheet having a thickness of 2 mm was subjected to a heat aging test in which the crosslinked sheet was held at 180° C. for 70 hours according to JIS K6257. The hardness, TB and EB of the sheet after the heat aging test were measured by the same method as the items of the hardness test and the tensile test.
From the difference in hardness before and after the heat aging test, AH (Duro-A) was obtained, and from TB and EB before and after the heat aging test, the rate of change after the test with respect to the value before the heat aging test was Ac (TB), Ac, respectively. (EB).

[Gehman twist test (low temperature twist test)]
The low-temperature twist test is performed in accordance with JIS K6261 (1993) using a Gehman twist tester to obtain T ₂ (°C), T ₅ (°C), T ₁₀ (°C) and T ₁₀₀ (°C) of the crosslinked sheet having a thickness of 2 mm. ) Was measured. These temperatures are indicators of the low temperature flexibility of the crosslinked rubber. For example, the lower T ₂ is, the better the low temperature flexibility is.

Claims (9)

It has a structural unit derived from ethylene [A1], a structural unit derived from an α-olefin [A2] having 4 to 20 carbon atoms, and a structural unit derived from a non-conjugated polyene [A3], and has the following (1) To 100 parts by mass of an ethylene/α-olefin/non-conjugated polyene copolymer (A) satisfying the requirements (1) to (3),
A composition for a power transmission belt, which comprises 0.1 to 200 parts by mass of carbon black (B).
(1) The molar ratio [[A1]/[A2]] of the structural unit derived from ethylene [A1] and the structural unit derived from the α-olefin [A2] having 4 to 20 carbon atoms is 40/60 or more. 90/10,
(2) The content ratio of the structural units derived from the non-conjugated polyene [A3] is 0.1 to 6.0 with the total of the structural units derived from [A1], [A2] and [A3] being 100 mol %. Mol%,
(3) The B value represented by the following formula (i) is 1.20 or more.
B value=([EX]+2[Y])/[2×[E]×([X]+[Y])]...(i)
[Here, [E], [X], and [Y] are moles of structural units derived from ethylene [A1], α-olefin [A2] having 4 to 20 carbon atoms, and non-conjugated polyene [A3], respectively. Shows the fraction, and [EX] represents the ethylene [A1]-C4 to C20 α-olefin [A2] dyad chain fraction. ] The composition for a power transmission belt according to claim 1, wherein the structural unit derived from the α-olefin [A2] having 4 to 20 carbon atoms in the copolymer (A) includes a structural unit derived from 1-butene. Further containing short fibers (C),
The composition for a power transmission belt according to claim 1 or 2, 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 copolymer (A). The composition for a power transmission belt according to claim 3, wherein the short fibers (C) are aramid fibers. The composition for a power transmission belt according to any one of claims 1 to 4, wherein the ethylene/α-olefin/non-conjugated polyene copolymer (A) further satisfies the requirement (4) below.
(4) Mooney viscosity ML _{(1+4) at} 100° C. is 5 to 150. The composition for a power transmission belt according to claim 1, further comprising a cross-linking aid having two or more ethylenic double bonds. A molded body formed from the composition for a power transmission belt according to claim 1. A cross-linked molded article formed from the composition for a power transmission belt according to claim 1. A transmission belt comprising the molded body according to claim 7 or the crosslinked molded body according to claim 8.