JP7421307B2 - Composition for power transmission belts - Google Patents

Description

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

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

Japanese Patent Application Publication No. 2001-310951 JP2012-215212A

According to studies by the present inventors, when an ethylene-propylene-nonconjugated polyene copolymer is used, the adhesive force (tack) between sheets formed from a power transmission belt composition containing the copolymer There is a tendency for the molding process to become difficult. An object of the present invention is to provide a composition for power transmission belts that has high adhesive strength and therefore excellent moldability.

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

[1] It has a structural unit derived from ethylene [A1], a structural unit derived from an α-olefin having 4 to 20 carbon atoms [A2], and a structural unit derived from a non-conjugated polyene [A3], and has the following: For power transmission belts containing 100 parts by mass of an ethylene/α-olefin/non-conjugated polyene copolymer (A) that satisfies 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 α-olefin [A2] having 4 to 20 carbon atoms is 40/60 to 90/10,
(2) The content ratio of structural units derived from non-conjugated polyene [A3] is 0.1 to 6.0, assuming that the total of structural units derived from [A1], [A2] and [A3] is 100 mol%. is mole%,
(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 having 4 to 20 carbon atoms [A2], and non-conjugated polyene [A3], respectively. [EX] indicates the ethylene [A1]-α-olefin [A2] dyad chain fraction having 4 to 20 carbon atoms. ]
[2] The power transmission belt according to [1] above, 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], further containing short fibers (C), wherein the content of the short fibers (C) is 0.1 to 100 parts by mass based on 100 parts by mass of the copolymer (A). Or the composition for power transmission belts according to [2].
[4] The composition for a power transmission belt according to [3] above, 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/nonconjugated polyene copolymer (A) further satisfies the following requirement (4).
(4) Mooney viscosity ML ₍₁₊₄₎ at 100°C is 5 to 150.
[6] The composition for a power transmission belt according to any one of [1] to [5] above, further containing a crosslinking aid having two or more ethylenic double bonds.
[7] A molded article formed from the composition for a power transmission belt according to any one of [1] to [6] above.
[8] A crosslinked molded article formed from the composition for power transmission belts according to any one of [1] to [6] above.
[9] A power transmission belt comprising 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 that has high adhesive strength and therefore excellent moldability.

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

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

In addition, component (A) contains a structural unit derived from ethylene [A1], a structural unit derived from at least one type of α-olefin having 4 to 20 carbon atoms [A2], and at least one type of non-conjugated polyene [ A3].
(1) The molar ratio [[A1]/[A2]] of the structural unit derived from ethylene [A1] and the structural unit derived from α-olefin [A2] having 4 to 20 carbon atoms is 40/60 to It's 90/10.
(2) The content ratio of structural units derived from non-conjugated polyene [A3] is 0.1 to 6.0, assuming that the total of structural units derived from [A1], [A2] and [A3] is 100 mol%. It is mole%.
(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 the mole fraction of structural units derived from ethylene [A1], α-olefin having 4 to 20 carbon atoms [A2], and non-conjugated polyene [A3], respectively. [EX] indicates the ethylene [A1]-α-olefin [A2] dyad chain fraction having 4 to 20 carbon atoms.

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, 1-nonadecene, 1 -Linear α-olefins such as eicosene; α-olefins containing side chains such as 4-methyl-1-pentene, 9-methyl-1-decene, 11-methyl-1-dodecene, and 12-ethyl-1-tetradecene can be mentioned. Among these, α-olefins having 4 to 10 carbon atoms are preferred, 1-butene, 1-hexene, and 1-octene are more preferred, and 1-butene is even more preferred.

The α-olefin [A2] having 4 to 20 carbon atoms can be used alone or in combination of two or more.
Ethylene-propylene-nonconjugated polyene copolymers in which the α-olefin is propylene have low adhesion between the resulting compositions, and therefore molded products and crosslinked molded products (hereinafter collectively referred to as " (also referred to as a "crosslinked) molded product" tends to have low moldability. Furthermore, this copolymer tends to have low kneading properties with short fibers (C).

On the other hand, in the present invention, at least component (A) is used as a rubber component. Since component (A) has a structural unit derived from α-olefin [A2] having 4 to 20 carbon atoms, it is presumed that the adhesive strength between the resulting compositions is increased, and therefore the composition has a higher adhesive strength. , has high moldability into (crosslinked) molded bodies, especially power transmission belts. In addition, component (A) also has excellent kneading properties with 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, 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, Examples include trienes such as 7-nonadiene. Among these, linear non-conjugated dienes such as 1,4-hexadiene, cyclic non-conjugated dienes such as 5-ethylidene-2-norbornene and 5-vinyl-2-norbornene are preferred, and cyclic non-conjugated dienes are more preferred; -ethylidene-2-norbornene and 5-vinyl-2-norbornene are more preferred.

Non-conjugated polyene [A3] can be used alone or in combination of two or more types.
As component (A), for example, 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 , ethylene/1-butene/1-octene/5-ethylidene-2-norbornene/5-vinyl-2-norbornene copolymer.

《Requirement (1)》
Component (A) consists of (1) a molar ratio of structural units derived from ethylene [A1] and structural units derived from α-olefin [A2] having 4 to 20 carbon atoms [[A1]/[A2]]; is 40/60 to 90/10. Component (A) having a molar ratio within the above range has an excellent balance between rubber elasticity at low temperatures and tensile strength at room temperature.

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

《Requirement (2)》
Component (A) has a content ratio of structural units derived from (2) non-conjugated polyene [A3], structural units derived from said [A1], structural units derived from said [A2], and said [A3]. It is 0.1 to 6.0 mol%, assuming the total derived structural units as 100 mol%. Component (A) whose content is within the above range has sufficient crosslinkability and flexibility.

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

《Requirement (3)》
Component (A) has (3) a B value expressed by the above formula (i) of 1.20 or more, preferably 1.20 to 1.80, more preferably 1.22 to 1.40.

Ethylene/α-olefin/non-conjugated polyene copolymers with a B value of less than 1.20 have a large compression set at low temperatures and may not have an excellent balance between rubber elasticity at low temperatures and tensile strength at room temperature. There is. Component (A) having a B value of 1.20 or more has high alternation of monomer units constituting the copolymer and low crystallinity, so that the processability of the resulting composition is improved.

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

《Requirement (4)》
Component (A) has (4) a Mooney viscosity ML ₍₁₊₄₎ at 100°C of preferably 5 to 150, more preferably 5 to 100, even more preferably 5 to 50. Component (A) having a Mooney viscosity within the above range has good processability and fluidity, exhibits good post-processing quality (ribbon handling properties), and has excellent rubber physical properties.

《Requirement (4')》
Component (A) has a (4') Mooney viscosity ML ₍₁₊₄₎ at 125°C of preferably 3 to 100, more preferably 3 to 70, even more preferably 3 to 30. Component (A) having a Mooney viscosity within the above range has good processability and fluidity, exhibits good post-processing quality (ribbon handling properties), 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 components (A).
The content of component (A) in the composition of the present invention is usually 20% by mass or more, preferably 30 to 90% by mass.

《Production method of component (A)》
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 International Publication No. 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) that reacts with the transition metal compound (a) to form an ion pair ( By copolymerizing ethylene [A1], an α-olefin having 4 to 20 carbon atoms [A2], and a non-conjugated polyene [A3] in the presence of an olefin polymerization catalyst containing b), component (A) can be obtained.

The above formula (a) will be explained.
M is a titanium atom, a zirconium atom or a hafnium atom.
R's are each independently a substituted aryl group in which one or more hydrogen atoms of the aryl group are substituted with an electron-donating group having a Hammett's 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 selected from the same or different combinations from a halogen atom, a hydrocarbon group having 1 to 20 carbon atoms, an anionic ligand, and a neutral ligand capable of coordinating with a lone pair of electrons, and is preferably a halogen atom. .

j is an integer from 1 to 4, preferably 2.
Examples of the aryl group in R include phenyl group, 1-naphthyl group, 2-naphthyl group, anthracenyl group, phenanthrenyl group, tetracenyl group, chrysenyl group, pyrenyl group, indenyl group, azulenyl group, pyrrolyl group, pyridyl group, furanyl group. and thiophenyl group, with phenyl group being preferred.

Electron-donating groups having a substituent constant σ of Hammett's rule of -0.2 or less are defined and exemplified as follows. Hammett's rule is an empirical rule proposed by L. P. Hammett in 1935 to quantitatively discuss the influence of substituents on the reaction or equilibrium of benzene derivatives, and its validity is widely recognized today. The substituent constants determined by 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 literature. For example, the article by Hansch and Taft [Chem. Rev., 91, 165 (1991)] provides a detailed description of a very wide range of substituents. However, the values of σp and σm described in these documents may differ slightly depending on the document even if the substituents are the same. In order to avoid confusion caused by such a situation, in this specification, as far as the substituents are mentioned, Table 1 (168-1) of the literature by Hansch and Taft [Chem. The values described on page 175 are defined as the substituent constants σp and σm of Hammett's rule. In this specification, an electron-donating group with Hammett's substituent constant σ of -0.2 or less means that when the electron-donating group is substituted at the para-position (4-position) of a phenyl group, σp is -0. It is an electron-donating group with a value of .2 or less, and when it is substituted at the meta-position (3-position) of a phenyl group, it is an electron-donating group with a σm of -0.2 or less. In addition, if the electron donating group is substituted at the ortho position (2nd 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 electron-donating groups with Hammett's substituent constant σp or σm of -0.2 or less include p-amino group (4-amino group), p-dimethylamino group (4-dimethylamino group), p-dimethylamino group (4-dimethylamino group), - 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) 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, or a halogen group, other than an electron-donating group having a Hammett's substituent constant σ of -0.2 or less. It may also have other substituents selected from atoms and halogen-containing groups. When the substituted aryl group has a plurality of other substituents, each of the other substituents may be the same or different.

The sum of the Hammett's rule substituent constants σ of each of the electron-donating groups and other substituents whose Hammett's rule substituent constant σ is −0.2 or less contained in one substituted aryl group is −0.15 or less. It is preferable that there be. Examples of such substituted aryl groups 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) p-methoxy-m,m-dimethylphenyl group (4-methoxy-3,5-dimethylphenyl group).

In Q, examples of the halogen atom 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 of anionic ligands include alkoxy groups, aryloxy groups, carboxylate groups, and sulfonate groups; examples of neutral ligands that can coordinate with lone pairs include trimethylphosphine, triethylphosphine, and triphenyl Examples 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. can be mentioned.

Examples of the organometallic compound (b-1) (excluding the organoaluminumoxy compound (b-2)) include trialkylaluminum such as trimethylaluminum, triethylaluminum, triisobutylaluminum, and tri-n-octylaluminum; Examples include organoaluminum compounds such as cycloalkylaluminum, isobutylaluminum dichloride, diethylaluminium chloride, ethylaluminum dichloride, ethylaluminum sesquichloride, methylaluminum dichloride, dimethylaluminum chloride, and diisobutylaluminum hydride.

Examples of the organoaluminumoxy compound (b-2) include conventionally known aluminoxane.
Examples of the compound (b-3) that reacts with the transition metal compound (a) to form an ion pair include those disclosed in Japanese Patent Publication No. 1-501950, Japanese Patent Publication No. 1-502036, and Japanese Patent Application Laid-open No. 3-179005. Lewis acids, ionic compounds described in publications, JP-A-3-179006, JP-A-3-207703, JP-A-3-207704, USP-5321106, International Publication No. 2015/122415, etc. 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 particulate solid. Among these, preferred inorganic compounds are porous oxides, inorganic halides, clays, clay minerals, and ion exchange layered compounds.

As the polymerization method, any of liquid phase polymerization methods such as solution (dissolution) polymerization and suspension polymerization, or gas phase polymerization methods can be used. 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 in any of the batch, semi-continuous and continuous methods. Furthermore, it is also possible to carry out the polymerization in two or more stages with different reaction conditions.

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

Examples of 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. Commercially available carbon blacks include, for example, "Asahi #55G", "Asahi #50HG", "Asahi #60G", "Asahi #60UG" (trade name, manufactured by Asahi Carbon Co., Ltd.), "Seest V", " SEAST SO" (trade name, manufactured by Tokai Carbon Co., Ltd.).

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

<Short fiber (C)>
It is preferable that the composition of the present invention further contains short fibers (C). By using short fibers (C), the modulus and mechanical strength of the (crosslinked) molded article formed from the composition can be improved. Since component (A) also has excellent kneadability with short fibers (C), the composition of the present invention tends to have excellent moldability even if it contains short fibers (C).

The short fibers (C) are made of synthetic resins such as polyamide, polyimide, polyester, polyvinyl alcohol, rayon, polyolefin, polyarylate, polyphenylene sulfide, polyetheretherketone, polyparaphenylenebenzobisoxazole, and fluorine-based polymers. Fibers: Natural fibers such as cotton and wood cellulose fibers can be mentioned. Among these, short fibers made of synthetic resin are preferred, and short fibers made of polyamide are more preferred. Short fibers (C) are usually not short fibers formed from component (A).

Examples of the polyamide include polycapramide, poly-ω-aminoheptanoic acid, poly-ω-aminononanoic acid, polyundecaneamide, polyethylenediamine adipamide, polytetramethylene adipamide, polyhexamethylene adipamide, and polyhexamethylene. Aliphatic polyamides such as sebaamide, polyhexamethylene dodecamide, polyoctamethylene adipamide, and polydecamethylene adipamide; polyparaphenylene terephthalamide (trade name "Kevlar", manufactured by DuPont-Toray), poly Metaphenylene isophthalamide, copolyparaphenylene-3,4'-oxydiphenyleneterephthalamide, polymethaxylylene adipamide, polymethaxylylene pimeramide, polymethaxylylene azeramide, polyparaxylylene azeramide, poly Examples include aromatic polyamides (aramids) such as paraxylylene decanamide.

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 resulting (crosslinked) molded product, and polyparaphenylene terephthalate is preferable. More preferred are lamid 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, and 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, and more preferably 1 to 20 μm.

The average fiber length of the short fibers (C) can be determined by, for example, taking a photograph of the short fibers using an optical microscope, measuring the lengths of 100 randomly selected short fibers in the photograph, and calculating the arithmetic average. It can be found by

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

The content of 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, and more preferably The amount is 3 to 20 parts by mass. Such an embodiment is preferable from the viewpoint of the modulus and mechanical strength of the (crosslinked) molded product obtained.

<Other ingredients>
It is preferable that the composition of the present invention further contains a crosslinking agent. The composition of the invention is selected from crosslinking aids, softeners, inorganic fillers, reinforcing agents, anti-aging agents, processing aids, activators, moisture absorbers, antistatic agents, colorants, lubricants and thickeners. It can further contain at least one kind. The compositions of the invention may further contain other polymers than component (A), such as elastomers and/or rubbers. Each of the components described below may be used alone or in combination of two or more.

《Crosslinking agent》
Examples of the crosslinking agent include crosslinking agents commonly used when crosslinking rubber, such as organic peroxides, sulfur compounds, phenolic resins, hydrosilicone compounds, amino resins, quinones or derivatives thereof, Examples include amine compounds, azo compounds, epoxy compounds, and isocyanate compounds. Among these, organic peroxides and sulfur compounds are preferred.

Examples of organic peroxides 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 crosslinking agent, the content of the organic peroxide is the same as that of component (A) and other polymers (rubber, etc.) that require crosslinking and are blended as necessary. The amount is usually 0.1 to 20 parts by weight, preferably 0.2 to 15 parts by weight, and more preferably 0.5 to 10 parts by weight, based on a total of 100 parts by weight.

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

Examples of crosslinking aids include sulfur; quinonedioxime crosslinking aids such as p-quinonedioxime; crosslinking aids having two or more ethylenic double bonds; maleimide crosslinking aids; zinc oxide (e.g. , ZnO#1, zinc oxide type 2 (JIS standard (K-1410), manufactured by Hakusui Tech Co., Ltd.), magnesium oxide, zinc white (for example, "META-Z102" (trade name; manufactured by Inoue Lime Industry Co., Ltd.), etc.) Examples include metal oxides such as zinc), and crosslinking aids having two or more ethylenic double bonds are preferred.

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

When the composition of the present invention contains a crosslinking auxiliary agent, the content of the crosslinking auxiliary agent is usually 0.5 to 10 mol, preferably 0.5 to 7 mol, per 1 mol of organic peroxide. More preferably, it is 1 to 5 mol.

When a sulfur compound is used as a crosslinking agent, specific examples 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 component (A) and other polymers (rubber, etc.) that require crosslinking and are blended as necessary. The amount is usually 0.3 to 10 parts by weight, preferably 0.5 to 7.0 parts by weight, and more preferably 0.7 to 5.0 parts by weight per 100 parts by weight.

When using a sulfur-based compound 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)penzothiazole), 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 diorthotolylguanidine; aldehyde amine-based vulcanization accelerators such as acetaldehyde/aniline condensates, butyraldehyde/aniline condensates, etc. Vulcanization accelerator: Imidazoline vulcanization accelerator such as 2-mercaptoimidazoline; Thiourea vulcanization accelerator such as diethylthiourea, dibutylthiourea; Tetramethylthiuram monosulfide, tetramethylthiuram disulfide, tetraethylthiuram disulfide, tetrabutylthiuram Thiuram-based vulcanization accelerators such as disulfide, dipentamethylene thiuram tetrasulfide; dithioate-based vulcanization accelerators such as zinc dimethyldithiocarbamate, zinc diethyldithiocarbamate, zinc dibutyldithiocarbamate, tellurium diethyldithiocarbamate; ethylenethiourea ( For example, thiourea-based vulcanization accelerators such as Suncella 22C (trade name; manufactured by Sanshin Kagaku Kogyo Co., Ltd.), N,N'-diethylthiourea, N,N'-dibutylthiourea; xanthate-based vulcanization accelerators such as zinc dibutylxatogenate. Vulcanization accelerator; other examples 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 component (A) and other polymers (rubber, etc.) that require crosslinking and are blended as necessary. The amount is usually 0.1 to 20 parts by weight, preferably 0.2 to 15 parts by weight, and more preferably 0.5 to 10 parts by weight.

The vulcanization aid can be preferably used when the crosslinking agent is a sulfur-based compound, such as zinc oxide (e.g., ZnO #1, zinc oxide 2, manufactured by Hakusui Tech), magnesium oxide, zinc white (e.g. , "META-Z102" (trade name; manufactured by Inoue Lime Industry Co., Ltd.) and other zinc oxides).

When the composition of the present invention contains a vulcanization aid, the content of the vulcanization aid is a total of 100 It is usually 1 to 20 parts by mass.

《Softener》
Examples of softeners include process oil, lubricating oil, paraffin oil, liquid paraffin, petroleum asphalt, petroleum softeners such as vaseline; coal tar softeners such as coal tar; castor oil, linseed oil, rapeseed oil, and Fatty oil-based softeners such as bean oil and coconut oil; waxes such as beeswax and carnauba wax; fatty acids or their salts such as ricinoleic acid, palmitic acid, stearic acid, barium stearate, and calcium stearate; naphthenic acid, pine oil, rosin or derivatives thereof; synthetic polymer substances such as terpene resins, petroleum resins, coumaron indene resins; ester softeners such as dioctyl phthalate and dioctyl adipate; others, microcrystalline wax, liquid polybutadiene, modified liquid polybutadiene, hydrocarbon synthesis Examples include lubricating oil, tall oil, and sub(factice), with petroleum softeners being preferred and process oils being more preferred.

When the composition of the present invention contains a softener, the content of the softener is based on a total of 100 parts by mass of component (A) and other polymers (elastomer, rubber, etc.) blended as necessary. It is usually 2 to 100 parts by weight, preferably 5 to 100 parts by weight.

《Inorganic filler》
Examples of the inorganic filler include light calcium carbonate, heavy calcium carbonate, talc, and clay. Among these, heavy calcium carbonate is preferred.

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

《Reinforcer》
Examples of the reinforcing agent include silica, calcium carbonate, activated calcium carbonate, finely divided talc, and differential silicic acid, excluding the carbon black (B) mentioned above.

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

《Anti-aging agent (stabilizer)》
By containing the anti-aging agent (stabilizer), the composition of the present invention can extend the life of a (crosslinked) molded article formed from the composition. Examples of anti-aging agents include amine-based anti-aging agents, phenol-based anti-aging agents, and sulfur-based anti-aging agents.

Examples of the amine antioxidant include aromatic secondary amine antioxidants such as phenylbutylamine and N,N-di-2-naphthyl-p-phenylenediamine. Examples of the phenolic anti-aging agent include dibutylhydroxytoluene and pentaerythritol tetrakis [3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate]. Examples of sulfur-based anti-aging agents include thioether-based anti-aging agents such as bis[2-methyl-4-(3-n-alkylthiopropionyloxy)-5-t-butylphenyl] sulfide; nickel dibutyldithiocarbamate, etc. Dithiocarbamate-based anti-aging agents; examples include 2-mercaptobenzoylimidazole, 2-mercaptobenzimidazole, zinc salt of 2-mercaptobenzimidazole, dilaurylthiodipropionate, and distearylthiodipropionate.

When the composition of the present invention contains an anti-aging agent, the content of the anti-aging agent is based on a total of 100 parts by mass of component (A) and other polymers (elastomer, rubber, etc.) blended as necessary. The amount is usually 0.3 to 10 parts by weight, preferably 0.5 to 7.0 parts by weight.

《Processing aid》
As the processing aid, a wide variety of processing aids that are generally blended into rubber can be used. Examples of processing aids include ricinoleic acid, stearic acid, palmitic acid, lauric acid, barium stearate, zinc stearate, calcium stearate, and esters. Among these, stearic acid is preferred.

When the composition of the present invention contains a processing aid, the content of the processing aid is based on a total of 100 parts by mass of component (A) and other polymers (elastomer, rubber, etc.) blended as necessary. The amount is usually 10 parts by mass or less, preferably 8.0 parts by mass or less.

《Activator》
Examples of the activator include amines such as di-n-butylamine, dicyclohexylamine, and monoelanolamine; diethylene glycol, polyethylene glycol, lecithin, triaryl utmerate, and zinc compounds of aliphatic carboxylic acids or aromatic carboxylic acids. Activators; zinc peroxide preparations; tadecyltrimethylammonium bromide, synthetic hydrotalcites, special quaternary ammonium compounds.

When the composition of the present invention contains an active agent, the content of the active agent is based on a total of 100 parts by mass of component (A) and other polymers (elastomer, rubber, etc.) blended as necessary. It is usually 0.2 to 10 parts by weight, preferably 0.3 to 5 parts by weight.

《Moisture absorbent》
Examples of the moisture absorbent include calcium oxide, silica gel, sodium sulfate, molecular sieve, zeolite, and white carbon.
When the composition of the present invention contains a hygroscopic agent, the content of the hygroscopic agent is based on a total of 100 parts by mass of component (A) and other polymers (elastomer, rubber, etc.) blended as necessary. It is usually 0.5 to 15 parts by weight, preferably 1.0 to 12 parts by weight.

《Other polymers》
The composition of the present invention may further contain other polymers than component (A).
Examples of other polymers that require crosslinking 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. It will be done.

Examples of other polymers that do not require crosslinking include block copolymers of styrene and butadiene (SBS), polystyrene-poly(ethylene-butylene)-polystyrene (SEBS), polystyrene-poly(ethylene-propylene)-polystyrene ( Styrene thermoplastic elastomer (TPS) such as SEPS), olefin thermoplastic elastomer (TPO), polyvinyl chloride elastomer (TPVC), ester thermoplastic elastomer (TPC), amide thermoplastic elastomer (TPA), urethane thermoplastic elastomer Examples include elastomers such as plastic elastomer (TPU) and other thermoplastic elastomers (TPZ).
When the composition of the present invention 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 component (A).

<Preparation of composition>
The composition of the present invention is prepared by mixing component (A), carbon black (B), short fibers (C) blended as necessary, and other components in a kneading machine such as a mixer, kneader, or roll. It can be prepared by kneading at a desired temperature using.

One embodiment of the composition of the invention is prepared, for example, as follows. Component (A), carbon black (B), short fibers (C) if necessary, and other predetermined components are put into a kneader and heated under predetermined heating conditions (e.g., 80 to 200°C for 30 minutes). -30 minutes) to make it homogeneous (Kneading A). In addition, in the A kneading, no crosslinking agent or the like is added, which crosslinks the component (A) when heated to the heating temperature of the A kneading. After the temperature of the mixture kneaded in A-kneading is then lowered to below the crosslinking temperature of the crosslinking agent (for example, 130°C or lower), the crosslinking agent etc. that were not added in A-kneading are added to the mixture, and a predetermined amount is obtained. The composition of the present invention can be obtained by further kneading and homogenizing under heating conditions (for example, roll temperature of 30 to 80°C for 1 to 30 minutes) (Kneading B).

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, more preferably 10 ~50. A composition having a Mooney viscosity within the above range exhibits good post-treatment quality and has excellent rubber physical properties.

[(Crosslinked) molded body, power transmission belt]
A (crosslinked) molded article can be obtained from the composition of the present invention. The composition of the present invention can be molded by thermoforming methods such as extrusion molding, injection molding, press molding, calendar molding, transfer molding, and 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 suitably used as a component of a power transmission belt. For example, the composition of the present invention has high adhesive strength suitable for molding processability and is excellent in belt processability. Further, by using the composition of the present invention, it is possible to produce a component for a power transmission belt that has high rubber elasticity, excellent abrasion 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; interlocking power transmission belts such as timing belts. The transmission belt is, for example, a transmission belt for automobiles, a transmission belt for motorcycles, or a transmission belt for general industrial machinery. Examples of the V-belt include a wrapped belt and a raw-edge belt.

One embodiment of the power transmission belt has, for example, an adhesive rubber part in which a core wire is embedded, and can further include a bottom rubber part formed on the lower surface of the adhesive rubber part. The transmission belt may have an upper canvas formed on the adhesive rubber part and/or a lower canvas formed under the bottom rubber, as 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, a crosslinked molded part formed from the composition of the present invention is preferably used as the adhesive rubber part and/or the bottom rubber part.

The core wire, which is a tensile member of the power transmission belt, extends in the longitudinal direction of the belt at the adhesive rubber portion. Examples of the core wire include polyester cords. 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 may be placed around the core wire and crosslinked to form an adhesive rubber portion adhered to the core wire. Examples of the canvas include those made of cotton, a blend of cotton and polyester, and those made of a blend of cotton and polyamide.

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

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

<B value>
Using o-dichlorobenzene-d ₄ /benzene-d ₆ (4/1 [v/v]) as the measurement solvent, ^{the 13} C-NMR spectrum (100 MHz, JEOL ECX400P) was measured at a measurement temperature of 120°C. , calculated based on the following formula (i).
B value = ([EX]+2[Y])/[2×[E]×([X]+[Y])]...(i)
Here, [E], [X] and [Y] are the mole fraction of structural units derived from ethylene [A1], α-olefin having 4 to 20 carbon atoms [A2], and non-conjugated polyene [A3], respectively. [EX] indicates the ethylene [A1]-α-olefin [A2] dyad chain fraction having 4 to 20 carbon atoms.

[Ethylene/α-olefin/non-conjugated polyene copolymer]
According to the description in [Synthesis Example C1] of International Publication No. 2015/122415, an ethylene/1-butene/5-ethylidene-2-norbornene (ENB) copolymer having the following physical properties was obtained. Hereinafter, this will be referred to as "EBDM-1".
The structure 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, BB-2 type, volume 1.7L, rotor 2WH), ZnO #1 and two types of zinc oxide ( 5 parts of JIS standard (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 anti-aging agent. benzimidazole), 2 parts of Irganox 1010 (pentaerythritol tetrakis [3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate]) as an anti-aging agent, Diana Process Oil as a softener. PW-380 (paraffinic process oil) was blended in an amount of 10 parts and then kneaded to obtain a blend 1.

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

Next, after confirming that the temperature of Formulation 1 reached 40°C, using a 6-inch roll, 6.8% of Kayakumil DCP-40C (40% by mass of dicumyl peroxide) was added to Formulation 1 as a crosslinking agent. The mixture was added and kneaded in an amount of 100% to obtain a blend 2.

The kneading conditions when preparing Compound 2 were: roll temperature: front roll/rear roll = 50°C/50°C, roll circumferential speed: front roll/rear roll = 18 rpm/15 rpm, roll gap: 3 mm, kneading time: 8 minutes. Compound 2 was obtained.

Compound 2 was pressed using a press molding machine at 170° C. for 15 minutes to produce a crosslinked sheet with 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 twist test, which will be described later.

Compound 2 was pressed at 170°C for 20 minutes using a press molding machine equipped with a cylindrical mold to produce a right cylindrical test piece with a thickness of 12.7 mm and a diameter of 29 mm. A test piece for compression set (CS) measurement was obtained.

[Examples 2-3, Comparative Examples 1-3]
The same procedure as in Example 1 was conducted except that the composition and curing system were based on those listed in Table 2.
Materials used in Examples and Comparative Examples are shown in Table 1 below.

[specific gravity]
A test piece was prepared by cutting out 1 g of the raw material polymer or Blend 1 (Kneading A). The test piece was attached to an automatic hydrometer (Model M-1, manufactured by Toyo Seiki Seisakusho) in an atmosphere of 25° C., and the specific gravity was measured from the difference in mass in air and in pure water. In Table 2, raw polymer refers to chloroprene rubber, 2060M or EBDM-1 (raw material polymer), and compound refers to Blend 1.

[Probe tack test]
Probe tack was measured for Formulation 1 using TAC-II manufactured by RHESCA in accordance with JIS Z3284. The conditions were: temperature 25°C, immersion speed: 120mm/min, preload: 600gf, test speed: 120mm/min, press time: 60s.

[Adhesiveness between compounds]
Compound 1 (Kneading A) was subjected to a press treatment at 190° C. for 10 minutes using a 50-ton press molding machine to produce a sheet with a thickness of 2 mm. The two sheets were pasted together and pressure was applied lightly by hand. The situation when two sheets pasted together were peeled off by hand was classified as follows.

<Evaluation>
◎: Even if you try to peel it off by hand, it will not peel off and the base material will be destroyed.
○: It is difficult to remove even if you try to remove it by hand, but it can be removed with the adhesive surface.
△: When I try to peel it off, I feel pressure on my hand, but it peels off.
×: When trying to peel it off, it peels off without feeling almost any pressure on the hand.

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

[Tensile test: modulus, tensile stress at break, tensile elongation at break]
A No. 3 dumbbell test piece described in JIS K6251 (1993) was prepared by punching out the crosslinked sheet with a thickness of 2 mm, and measurements were performed using this test piece according to the method specified in JIS K6251 Section 3. A tensile test was conducted at a temperature of 25°C and a tensile speed of 500 mm/min, and the tensile stress (25% modulus (M25)), tensile stress at break (TB), and tensile elongation at break ( EB) was measured.

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

[Heat resistance test (heat aging resistance test)]
A heat aging test was conducted on the crosslinked sheet having a thickness of 2 mm by holding it at 180° C. for 70 hours in accordance with JIS K6257. The hardness, TB and EB of the sheet after the heat aging test were measured in the same manner as in the hardness test and tensile test items.
AH (Duro-A) is determined from the difference in hardness before and after the heat aging test, 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 is calculated as Ac (TB) and Ac, respectively. (EB).

[Gehman twist test (low temperature twist test)]
The low-temperature torsion test was performed using a Gehman torsion tester in accordance with JIS K6261 (1993) to determine T ₂ (°C), T ₅ (°C), T ₁₀ (°C) and T ₁₀₀ (°C) of the crosslinked sheet with a thickness of 2 mm. ) was measured. These temperatures are indicators of the low temperature flexibility of the crosslinked rubber. For example, the lower the _T2 , the better the low temperature flexibility.

Claims (8)

It has a structural unit derived from ethylene [A1], a structural unit derived from an α-olefin having 4 to 20 carbon atoms [A2], and a structural unit derived from a non-conjugated polyene [A3], and has the following (1) ~100 parts by mass of an ethylene/α-olefin/non-conjugated polyene copolymer (A) that satisfies the requirements of (3) and (4') ;
0.1 to 200 parts by mass of carbon black (B) ,
short fibers (C);
Contains
The average fiber length of the short fibers (C) is 1 to 20 μm,
The content of the short fiber (C) is 3 to 20 parts by mass based on 100 parts by mass of the copolymer (A),
In accordance with JIS Z3284, the peak value of the probe tack test is 394 gf or more when measured under the conditions of temperature 25 ° C, Immersion speed: 120 mm/min, Preload: 600 gf, Test speed: 120 mm/min, Press time: 60 s. , a composition for power transmission belts.
(1) The molar ratio [[A1]/[A2]] of the structural unit derived from ethylene [A1] and the structural unit derived from α-olefin [A2] having 4 to 20 carbon atoms is 40/60 to 90/10,
(2) The content ratio of structural units derived from non-conjugated polyene [A3] is 0.1 to 6.0, assuming that the total of structural units derived from [A1], [A2] and [A3] is 100 mol%. is mole%,
(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 having 4 to 20 carbon atoms [A2], and non-conjugated polyene [A3], respectively. [EX] indicates the ethylene [A1]-α-olefin [A2] dyad chain fraction having 4 to 20 carbon atoms. ]
(4') Mooney viscosity ML ₍₁₊₄₎ at 125°C is 3 to 70. The composition for a power transmission belt according to claim 1, wherein the structural unit derived from α-olefin [A2] having 4 to 20 carbon atoms in the copolymer (A) includes a structural unit derived from 1-butene. The composition for a power transmission belt according to claim 1 or 2 , wherein the short fibers (C) are aramid fibers. The composition for a power transmission belt according to any one of claims 1 to 3 , wherein the ethylene/α-olefin/nonconjugated polyene copolymer (A) further satisfies the following requirement (4).
(4) Mooney viscosity ML ₍₁₊₄₎ at 100°C is 5 to 150. The composition for a power transmission belt according to any one of claims 1 to 4 , further comprising a crosslinking aid having two or more ethylenic double bonds. A molded article formed from the composition for a power transmission belt according to any one of claims 1 to 5 . A crosslinked molded article formed from the composition for power transmission belt according to any one of claims 1 to 5 . A power transmission belt comprising the molded article according to claim 6 or the crosslinked molded article according to claim 7 .