JP2023119377A - Composition for transmission belt - Google Patents

Abstract

To provide a composition for a transmission belt excellent in tackiness and green strength advantageous for moldability.SOLUTION: A composition for a transmission belt includes: 40 to 90 pts.mass of ethylene-α-olefin-nonconjugated polyene copolymer (A) satisfying a prescribed condition and having a structural unit derived from ethylene [A1], a structural unit derived from α-olefin [A2] having 4 to 20 carbon atoms, and a structural unit derived from nonconjugated polyene [A3]; 0.1 to 200 pts.mass of carbon black (B); 0.1 to 100 pts.mass of staple fibers (C); and 10 to 60 pts.mass of ethylene-α-olefin copolymer (D) having a structural unit derived from ethylene and a structural unit derived from α-olefin having 3 to 20 carbon atoms (where a total of the components (A) and (D) is 100 pts.mass).SELECTED DRAWING: None

Description

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

Power transmission belts are widely used in automobiles, scooters and general industrial fields, for example, as friction transmission belts such as V-belts and V-ribbed belts such as wrapped belts and raw edge belts, and as meshing transmission belts such as timing belts. there is

Adhesion, high elasticity and wear resistance are required for such transmission belts. In order to satisfy these characteristics, chloroprene rubber is often used as a rubber material for power transmission belts. However, in recent years, the demand for improved heat resistance and cold resistance as well as for lighter weight has increased, and ethylene/propylene/non-conjugated polyene copolymer (EPT) rubber has been used in place of chloroprene rubber. It is being studied (see Patent Documents 1 and 2, for example).

Japanese Patent Application Laid-Open No. 2001-310951 JP 2012-215212 A

In Patent Documents 1 and 2, short fibers are blended into EPT rubber, but since EPT rubber has poor compatibility with short fibers, it tends to be difficult to form a belt due to poor kneading and insufficient adhesiveness. . In addition, further improvement in green strength (strength before cross-linking) required during molding is also required.

An object of the present invention is to provide a composition for a power transmission belt that is excellent in adhesiveness and green strength, which is advantageous for moldability.

The inventor of the present invention has made intensive studies to solve the above problems. As a result, they found that the above problems could be solved by blending specific amounts of a specific ethylene/α-olefin/non-conjugated polyene copolymer, carbon black, short fibers, and an ethylene/α-olefin copolymer. The present invention has been completed.

The power transmission belt composition which is one embodiment of the present invention includes, for example, a structural unit derived from ethylene [A1], a structural unit derived from an α-olefin [A2] having 4 to 20 carbon atoms, and a non-conjugated polyene 40 to 90 parts by mass of an ethylene/α-olefin/non-conjugated polyene copolymer (A) having a structural unit derived from [A3] and satisfying the requirements of (1) to (3) below, and carbon black ( B) 0.1 to 200 parts by mass, short fibers (C) 0.1 to 100 parts by mass, a structural unit derived from ethylene, and a structural unit derived from an α-olefin having 3 to 20 carbon atoms 10 to 60 parts by mass of ethylene/α-olefin copolymer (D) (provided that the total of components (A) and (D) is 100 parts by mass).
(1) The molar ratio [[A1]/[A2]] between 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 to 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%. in mol %.
(3) The B value represented by the following formula (i) is 1.20 or more.
B value = ([EX] + 2 [Y]) / [2 x [E] x ([X] + [Y])] (i)
[Here, [E], [X] and [Y] are respectively moles of structural units derived from ethylene [A1], α-olefins having 4 to 20 carbon atoms [A2], and non-conjugated polyene [A3] [EX] indicates ethylene [A1]-C4-C20 α-olefin [A2] diad chain fraction. ]

ADVANTAGE OF THE INVENTION According to this invention, the composition for transmission belts which is excellent in adhesiveness and green strength which are advantageous for moldability can be provided.

The present invention will be described in detail below.
[Composition for power transmission belt]
The power transmission belt composition 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) described below, carbon black (B), It contains short fibers (C) and an ethylene/α-olefin copolymer (D).

<Ethylene/α-olefin/non-conjugated polyene copolymer (A)>
The ethylene/α-olefin/non-conjugated polyene copolymer (A) comprises a structural unit derived from ethylene [A1], a structural unit derived from an 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 (A) is also referred to as "component (A)". In one embodiment, component (A) preferably satisfies requirement (4) or (4') described below.

The component (A) comprises a structural unit derived from ethylene [A1], a structural unit derived from at least one type of α-olefin [A2] having 4 to 20 carbon atoms, and at least one type of non-conjugated polyene [ A3].

(1) The molar ratio [[A1]/[A2]] between 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 to 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%. in mol %.
(3) The B value represented by the following formula (i) is 1.20 or more.
B value = ([EX] + 2 [Y]) / [2 x [E] x ([X] + [Y])] (i)
Here, [E], [X] and [Y] are respectively ethylene [A1], α-olefins having 4 to 20 carbon atoms [A2], and non-conjugated polyene [A3]. [EX] indicates the diad chain fraction of ethylene [A1]-α-olefin having 4 to 20 carbon atoms [A2].

The α-olefins [A2] having 4 to 20 carbon atoms include, for example, 1-butene, 1-pentene, 1-hexene, 1-heptene, 1-octene, 1-nonene, 1-decene, 1-nonadecene, 1 - 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, 12-ethyl-1-tetradecene are 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-olefins [A2] having 4 to 20 carbon atoms can be used alone or in combination of two or more.
The ethylene/propylene/non-conjugated polyene copolymer in which the α-olefin is propylene has low adhesion between the resulting compositions, and therefore the molded article and crosslinked molded article of the composition (hereinafter collectively referred to as " It tends to be less moldable into a (crosslinked) molded product. In addition, this copolymer tends to have low kneadability with the 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 an α-olefin [A2] having 4 to 20 carbon atoms, it is presumed that the adhesion between the resulting compositions was increased. , (cross-linked) molded products, especially high moldability to power transmission belts. In addition, the component (A) is also excellent in kneadability with the short fibers (C).

Non-conjugated polyenes [A3] include, for example, 1,4-hexadiene, 1,6-octadiene, 2-methyl-1,5-hexadiene, 6-methyl-1,5-heptadiene, 7-methyl-1,6 - Linear non-conjugated 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.
Component (A) includes, for example, ethylene/1-butene/1,4-hexadiene copolymer, ethylene/1-pentene/1,4-hexadiene copolymer, ethylene/1-hexene/1,4-hexadiene Copolymers, ethylene/1-heptene/1,4-hexadiene copolymers, ethylene/1-octene/1,4-hexadiene copolymers, ethylene/1-nonene/1,4-hexadiene copolymers, 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 copolymers, ethylene/1-butene/1-octene/5-ethylidene-2-norbornene copolymers, ethylene/1-butene/5-ethylidene-2-norbornene/5-vinyl-2-norbornene copolymers, 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 copolymers.

《Requirements (1)》
Component (A) consists of (1) a molar ratio of a structural unit derived from ethylene [A1] to a structural unit derived from an 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 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. Also, the upper limit of [A1]/[A2] is preferably 80/20, more preferably 75/25, still more preferably 70/30.

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

The lower limit of the content of structural units 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 %, still more preferably 3.0 mol %.

《Requirement (3)》
(3) Component (A) has a B value represented by formula (i) of 1.20 or more, preferably 1.20 to 1.80, and 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 The component (A) having a B value of 1.20 or more has high alternating 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 copolymerization monomer chain distribution 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 reports by JC Randall [Macromolecules, 15, 353 (1982)], J. Ray [Macromolecules, 10, 773 (1977)]. On the other hand, in (1) to (2) above, the structural unit derived from ethylene [A1], the structural unit derived from α-olefin [A2] having 4 to 20 carbon atoms, and the structure derived from non-conjugated polyene [A3] The molar amount of units can be determined by intensity measurement with a ¹ H-NMR spectrometer.

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

<<Requirement (4')>>
Component (A) (4′) has a Mooney viscosity ML ₍₁₊₄₎ of 125°C at 125°C of preferably 3 to 100, more preferably 3 to 70, still more preferably 3 to 30. Component (A) having a Mooney viscosity within the above range has good processability and fluidity, exhibits good post-treatment quality (ribbon handleability), and has excellent rubber physical properties.

The composition of the present invention may contain one component (A) or may contain two or more components (A).
The content of component (A) in the composition of the present invention is 40 to 90 parts by mass, preferably 42 to 88 parts by mass, with respect to 100 parts by mass of component (A) and component (D) described later. , more preferably 45 to 85 parts by mass. Such an aspect is preferable from the viewpoint of workability of the composition of the present invention.

In addition, the content of component (A) in the composition of the present invention is usually 10% by mass or more, preferably 20 to 80% by mass.

<<Method for producing 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 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 (b-3) that reacts with the organometallic compound (b-1), the organoaluminumoxy compound (b-2), and the transition metal compound (a) to form an ion pair ( b) 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 can be obtained.

The above formula (a) will be explained.
M is a titanium atom, a zirconium atom or a hafnium atom.
Each R is independently a substituted aryl group in which one or more hydrogen atoms of an aryl group are substituted with an electron-donating group having a Hammett 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 selected in the same or different combination 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 electron pair, preferably a halogen atom. .

j is an integer from 1 to 4, preferably 2;
Aryl groups for R include, for example, 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 and thiophenyl groups, with phenyl groups being preferred.

An electron-donating group having a Hammett rule substituent constant σ of −0.2 or less is defined and exemplified below. Hammett's rule is an empirical rule proposed by L. P. Hammett in 1935 to quantitatively discuss the effects of substituents on reactions or equilibria of benzene derivatives, and is widely accepted today. 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 literatures. For example, the article by Hansch and Taft [Chem. Rev., 91, 165 (1991)] gives a detailed description of a very wide variety of substituents. However, the values of σp and σm described in these documents may be slightly different depending on the documents even if the substituents are the same. In order to avoid confusion caused by this situation herein, wherever the substituents are listed, Table 1 of Hansch and Taft [Chem. Rev., 91, 165 (1991)] (168- 175) are defined as Hammett's substituent constants σp and σm. In the present specification, an electron-donating group having a substituent constant σ of Hammett's rule of −0.2 or less means that σp is −0 when the electron-donating group is substituted at the para-position (4-position) of the phenyl group. It is an electron-donating group of .2 or less, and an electron-donating group of -0.2 or less when substituted at the meta-position (3-position) of a phenyl group. In addition, when the electron-donating group is substituted at the ortho position (2-position) of the phenyl group, or when substituted at any position of the aryl group other than the phenyl group, σp is -0.2 or less. It is an electron-donating group.

The electron-donating group having a Hammett rule substituent constant σ or σ of −0.2 or less includes, for example, 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) containing groups; tertiary hydrocarbon groups such as pt-butyl group (4-t-butyl group); and silicon-containing groups such as p-trimethylsiloxy group (4-trimethylsiloxy group).

Preferably, 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 other than an electron-donating group having a substituent constant σ of Hammett's rule of −0.2 or less, a silicon-containing group, a nitrogen-containing group, an oxygen-containing group, a halogen It may 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.

Hammett's substituent constant σ of -0.2 or less in one substituted aryl group and the total sum of Hammett's substituent constants σ of each of the electron-donating groups and other substituents is −0.15 or less Preferably. 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, the halogen atom is exemplified by fluorine, chlorine, bromine and iodine; the hydrocarbon group having 1 to 20 carbon atoms is 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 capable of coordinating with a lone pair include trimethylphosphine, triethylphosphine, 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. is mentioned.

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

Examples of the organoaluminumoxy compound (b-2) include conventionally known aluminoxanes.
Examples of the compound (b-3) that reacts with the transition metal compound (a) to form an ion pair include: Publications, JP-A-3-179006, JP-A-3-207703, JP-A-3-207704, USP-5321106, WO 2015/122415 Lewis acids described in, ionic compounds, Borane compounds and carborane compounds are included.

The olefin polymerization catalyst may optionally contain a carrier (c). The carrier (c) is an inorganic compound or an organic compound, and is a granular or particulate solid. Among these inorganic compounds, porous oxides, inorganic halides, clays, clay minerals, and ion-exchange layered compounds are preferred.

The polymerization can be carried out by either liquid phase polymerization such as solution (dissolution) polymerization or suspension polymerization, or gas phase polymerization. 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 a batch system, a semi-continuous system and a continuous system. 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 resulting (crosslinked) molded article.

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. Examples of commercially available carbon black include "Asahi #55G", "Asahi #50HG", "Asahi #60G", "Asahi #60UG", and "Asahi #70" (trade name, manufactured by Asahi Carbon Co., Ltd.), "Seist V" and "Seist SO" (trade name, manufactured by Tokai Carbon Co., Ltd.) can be mentioned.

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 300 parts by mass, preferably 10 to 250 parts by mass, with respect to 100 parts by mass of component (A) and component (D) in total. parts, more preferably 20 to 200 parts by mass. Such an aspect is preferable from the viewpoint of the mechanical strength of the resulting (crosslinked) molded article and the workability of the composition of the present invention.

<Short fiber (C)>
The composition of the present invention contains short fibers (C). By using the short fibers (C), the modulus and mechanical strength of the (crosslinked) molded article formed from the composition can be improved. Since the component (A) is also excellent in kneadability with the short fibers (C), the composition of the present invention tends to be excellent in moldability.

The short fibers (C) are made of, for example, synthetic resins such as polyamide, polyimide, polyester, polyvinyl alcohol, rayon, polyolefin, polyarylate, polyphenylene sulfide, polyetheretherketone, polyparaphenylenebenzobisoxazole, 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. Staple fibers (C) are generally not staple fibers formed from component (A).

Examples of polyamides include polycapramide, poly-ω-aminoheptanoic acid, poly-ω-aminononanoic acid, polyundecaneamide, polyethylenediamineadipamide, polytetramethyleneadipamide, polyhexamethyleneadipamide, and polyhexamethylene. Aliphatic polyamides such as sebacamide, polyhexamethylenedodecanamide, polyoctamethyleneadipamide, and polydecamethyleneadipamide; metaphenylene isophthalamide, copolyparaphenylene-3,4′-oxydiphenylene terephthalamide, polymetaxylyleneadipamide, polymetaxylylenepimeramide, polymetaxylyleneazelamide, polyparaxylyleneazelamide, poly Aromatic polyamides (aramids) such as paraxylylene decanamide can be mentioned.

The short fibers (C) are preferably short fibers made of aliphatic polyamide, that is, nylon short fibers, more preferably nylon 6 or nylon 66, from the viewpoint of improving the tensile stress and tear strength of the obtained (crosslinked) molded article and from the viewpoint of cost. preferable.

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

For the average fiber length of the short fibers (C), for example, the short fibers are photographed with an optical microscope, the lengths of 100 randomly selected short fibers are measured in the obtained photograph, and the arithmetic mean is calculated. can be obtained by

The short fibers (C) may be chopped fiber (cut fiber) short fibers or fibril-containing pulp-like short fibers.

The composition of the present invention may contain one type of staple fiber (C), or may contain two or more types of staple fiber (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 100 parts by mass, based on 100 parts by mass of components (A) and (D). 50 parts by mass, more preferably 3 to 30 parts by mass. Such a mode is preferable from the viewpoint of the modulus and mechanical strength of the obtained (crosslinked) molded article.

<Ethylene/α-olefin copolymer (D)>
The composition of the present invention comprises an ethylene/α-olefin copolymer (D) having structural units derived from ethylene and structural units derived from an α-olefin having 3 to 20 carbon atoms (hereinafter “component (D)” Also called.) including.

As the α-olefin, an α-olefin having preferably 3 to 12 carbon atoms, more preferably 4 to 8 carbon atoms is desirable from the viewpoint of obtaining a transmission belt having excellent mechanical strength.
Specific examples of such α-olefins include propylene, 1-butene, 1-pentene, 1-hexene, 4-methyl-1-pentene, 1-heptene, 1-octene, 1-nonene, 1- Decene, 1-undecene, 1-dodecene, 1-tridecene, 1-tetradecene, 1-pentadecene, 1-hexadecene, 1-heptadecene, 1-octadecene, 1-nonadecene, 1-eicosene, 9-methyl-1-decene, 11-methyl-1-dodecene, 12-ethyl-1-tetradecene and the like. Among them, propylene, 1-butene, 1-hexene, 1-octene and the like are preferably used, and 1-butene is particularly preferable. These α-olefins may be used alone or in combination of two or more.

In the component (D), the content of structural units derived from ethylene is preferably 50 to 85 mol%, more preferably 50 to 80 mol% (provided that the structural units derived from ethylene and The sum of 20 α-olefin-derived structural units is 100 mol%). When the content of structural units derived from ethylene is within the above range, a composition having excellent compatibility with component (A) can be obtained.

Component (D) preferably satisfies at least one of the following requirements (i) to (iv).
(i) Melting Point The melting point of component (D) is preferably 110°C or less, more preferably 0 to 105°C, and even more preferably 0 to 100°C. When the melting point of the component (D) is within the above range, the unmelted component (D) does not remain even at a low kneading temperature, and in particular, a transmission belt with a small mold shrinkage rate and excellent abrasion resistance can be obtained. . The melting point of component (D) can be measured by the method described in JIS K7121.

(ii) Density The density of component (D) is preferably 840-920 kg/m ³ , more preferably 850-915 kg/m ³ , still more preferably 855-910 kg/m ³ . When the density is within the above range, it is possible to obtain a power transmission belt with a small mold shrinkage rate and excellent strength characteristics and abrasion resistance. The density of component (D) can be measured by the method described in ASTM D1505.

(iii) MFR
MFR of component (D) at 190° C. and 2.16 kg is preferably 0.1 to 50 g/10 min, more preferably 0.2 to 30.0 g/10 min, still more preferably 0.3 to 10 g /10 min. When the MFR is within the above range, it is possible to obtain a composition with a small molding shrinkage and excellent workability. The MFR of component (D) can be measured by the method described in ASTM D1238.

(iv) Mw/Mn
The ratio Mw/Mn of the weight average molecular weight Mw to the number average molecular weight Mn determined by gel permeation chromatography (GPC) of component (D) is preferably in the range of 1.5 to 10.0.

The weight average molecular weight (Mw) of component (D) determined by GPC is preferably 10,000 to 500,000, more preferably 20,000 to 300,000, and still more preferably 20,000 to 200. ,000.

The number average molecular weight (Mn) of component (D) determined by GPC is preferably 1,000 to 250,000, more preferably 2,000 to 150,000, and still more preferably 2,000 to 100. ,000.

When the weight average molecular weight of the component (D) is within the above range, it is possible to obtain a power transmission belt with a small molding shrinkage and excellent abrasion resistance. In addition, when the low molecular weight component is low, volatilization and floating of the low molecular weight component are less likely to occur in the resulting power transmission belt, which is preferable.

Component (D) is preferably solid at room temperature to about 100°C, preferably at temperatures around 90°C.

Component (D) can be produced, for example, by copolymerizing ethylene and α-olefin using a vanadium catalyst, Ziegler-Natta catalyst or metallocene catalyst by a conventionally known method. A method of synthesizing using a metallocene catalyst is preferable from the viewpoint of being able to easily obtain a copolymer that satisfies the above physical properties. A method of synthesis using a catalyst containing a compound, etc., or a catalyst comprising a metallocene compound and an organoaluminum oxy compound or an ionized ionic compound described in JP-A-9-40586 is more preferable.

The composition of the present invention may contain one component (D) or may contain two or more components (D).
The content of component (D) in the composition of the present invention is 10 to 60 parts by mass, preferably 12 to 48 parts by mass, with respect to a total of 100 parts by mass of component (A) and component (D). It is preferably 15 to 55 parts by mass. Such an embodiment is preferable because the obtained composition is excellent in adhesiveness and green strength, which are advantageous for moldability.

<Other ingredients>
Preferably, the composition of the present invention further contains a cross-linking agent. The composition of the present invention contains a cross-linking aid, a softening agent, an inorganic filler, a reinforcing agent, an anti-aging agent, a processing aid, an activator, a moisture absorbent, an antistatic agent, a coloring agent, an α,β-unsaturated organic acid, can further contain at least one selected from metal salts of, lubricants and thickeners. The composition of the present invention may further contain other polymers than components (A) and (D), such as elastomers and/or rubbers. Each component 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 commonly used for cross-linking 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 peroxy isopropyl carbonate, diacetyl peroxide, lauroyl peroxide, 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 should be adjusted according to the content of component (A), component (D) and other components that require cross-linking that are blended as necessary. It is usually 0.1 to 20 parts by mass, preferably 0.2 to 15 parts by mass, and more preferably 0.5 to 10 parts by mass, based on 100 parts by mass of polymer (rubber, etc.).

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

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

The number of ethylenic double bonds in the cross-linking aid having two or more ethylenic double bonds is preferably 2-6, more preferably 2-4. By using the cross-linking aid, it is believed that a good network can be formed, for example, between the copolymer (A) and the short fibers (C). Examples of cross-linking aids 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; allyl-based cross-linking aids such as allyl isocyanurate; and vinyl-based cross-linking aids such as divinylbenzene. Among these, (meth)acrylic cross-linking aids are preferable, and ethylene glycol dimethacrylate is more preferable.

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

When a sulfur compound is used as a cross-linking 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 cross-linking agent, the content of the sulfur-based compound is adjusted to the components (A), (D), and other polymers ( rubber, etc.) is usually 0.3 to 10 parts by mass, preferably 0.5 to 7.0 parts by mass, more preferably 0.7 to 5.0 parts by mass.

When using a sulfur-based compound as a cross-linking agent, it is preferable to use a vulcanization accelerator together. Examples of vulcanization accelerators 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 diorthotolylguanidine; 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 vulcanization accelerators such as disulfide and dipentamethylenethiuram tetrasulfide; dithioate vulcanization accelerators such as zinc dimethyldithiocarbamate, zinc diethyldithiocarbamate, zinc dibutyldithiocarbamate, and tellurium diethyldithiocarbamate; ethylenethiourea ( For example, Suncellar 22C (trade name; manufactured by Sanshin Kagaku Kogyo Co., Ltd.), N,N'-diethylthiourea, N,N'-dibutylthiourea and other thiourea-based vulcanization accelerators; 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 varies depending on the amount of component (A), component (D) and other polymers (rubber etc.) 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.

The vulcanization aid can be preferably used when the cross-linking agent is a sulfur-based compound. , zinc oxide such as “META-Z102” (trade name; manufactured by Inoue Lime Industry Co., Ltd.).

When the composition of the present invention contains a vulcanization aid, the content of the vulcanization aid is adjusted to the components (A), (D) and other polymers (rubber etc.) is usually 1 to 20 parts by mass with respect to the total 100 parts by mass.

《Softener》
Examples of softening agents include petroleum softening agents such as process oil, lubricating oil, paraffin oil, liquid paraffin, petroleum asphalt, and vaseline; coal tar softening agents such as coal tar; Fatty oil-based softeners such as soybean oil and coconut oil; Waxes such as beeswax and carnauba wax; Fatty acids such as ricinoleic acid, palmitic acid, stearic acid, barium stearate, calcium stearate and salts thereof; Naphthenic acid, pine oil, rosin or derivatives thereof; synthetic high-molecular substances such as terpene resins, petroleum resins, and coumarone-indene resins; ester-based softeners such as dioctyl phthalate and dioctyl adipate; Lubricating oils, tall oils and subs (factices) are included, with petroleum-based softeners being preferred, and process oils being more preferred.

When the composition of the present invention contains a softening agent, the content of the softening agent is 100 mass in total of component (A), component (D) and other polymers (elastomers, rubbers, etc.) blended as necessary. 2 to 100 parts by mass, preferably 5 to 100 parts by mass.

《Inorganic filler》
Inorganic fillers include, for example, light calcium carbonate, heavy calcium carbonate, talc, and clay. Among these, ground calcium carbonate is preferred.

When the composition of the present invention contains an inorganic filler, the content of the inorganic filler is the sum of component (A), component (D) and other polymers (elastomers, rubbers, etc.) blended as necessary. It is usually 2 to 50 parts by mass, preferably 5 to 50 parts by mass, per 100 parts by mass.

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

When the composition of the present invention contains a reinforcing agent, the content of the reinforcing agent is 100 mass in total of component (A), component (D) and other polymers (elastomers, rubbers, etc.) blended as necessary. 0.1 to 100 parts by mass, preferably 5 to 30 parts by mass.

《Anti-aging agent (stabilizer)》
By containing an antioxidant (stabilizer) in the composition of the present invention, the life of a (crosslinked) molded article formed from the composition can be extended. Anti-aging agents include, for example, amine-based anti-aging agents, phenol-based anti-aging agents, and sulfur-based anti-aging agents.

Examples of amine antioxidants include aromatic secondary amine antioxidants such as phenylbutylamine and N,N-di-2-naphthyl-p-phenylenediamine. Phenolic anti-aging agents include, for example, dibutylhydroxytoluene and pentaerythritol tetrakis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate]. Examples of sulfur-based antioxidants include thioether-based antioxidants such as bis[2-methyl-4-(3-n-alkylthiopropionyloxy)-5-t-butylphenyl]sulfide; nickel dibutyldithiocarbamate and the like; Dithiocarbamate antioxidants; 2-mercaptobenzimidazole, 2-mercaptobenzimidazole, zinc salt of 2-mercaptobenzimidazole, dilauryl thiodipropionate, distearyl thiodipropionate.

When the composition of the present invention contains an anti-aging agent, the content of the anti-aging agent is the sum of component (A), component (D) and other polymers (elastomers, rubbers, etc.) blended as necessary. It is usually 0.3 to 10 parts by mass, preferably 0.5 to 7.0 parts by mass, per 100 parts by mass.

《Processing aid》
As the processing aid, a wide variety of processing aids that are generally blended with 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 the sum of component (A), component (D) and other polymers (elastomers, rubbers, etc.) blended as necessary. It is usually 10 parts by mass or less, preferably 8.0 parts by mass or less with respect to 100 parts by mass.

《Activator》
Active agents include, for example, amines such as di-n-butylamine, dicyclohexylamine, and monoelanolamine; diethylene glycol, polyethylene glycol, lecithin, triarylutemellilate, zinc compounds of aliphatic carboxylic acids or aromatic carboxylic acids, and the like. Active agents; zinc peroxide preparations; ktadecyltrimethylammonium bromide, synthetic hydrotalcite, special quaternary ammonium compounds.

When the composition of the present invention contains an active agent, the content of the active agent is 100 mass in total of component (A), component (D) and other polymers (elastomers, rubbers, etc.) blended as necessary. 0.2 to 10 parts by mass, preferably 0.3 to 5 parts by mass.

《Moisture Absorber》
Moisture absorbents include, for example, calcium oxide, silica gel, sodium sulfate, molecular sieves, zeolites, and white carbon.
When the composition of the present invention contains a moisture absorbent, the content of the moisture absorbent is a total of 100 mass of component (A), component (D) and other polymers (elastomers, rubbers, etc.) blended as necessary. 0.5 to 15 parts by mass, preferably 1.0 to 12 parts by mass.

<<Metal salts of α,β-unsaturated organic acids>>
When the composition of the present invention contains a metal salt of an α,β-unsaturated organic acid, the dynamic fatigue resistance and wear resistance of the composition can be improved in a well-balanced manner.

Examples of metal salts of α,β-unsaturated organic acids include acrylic acid, methacrylic acid, maleic acid, fumaric acid, ethacrylic acid, vinyl-acrylic acid, itaconic acid, methylitaconic acid, aconitic acid, methylaconitic acid, Metal salts of acids such as crotonic acid, alpha-methylcrotonic acid, cinnamic acid and 2,4-dihydroxycinnamic acid. These salts can be zinc, cadmium, calcium, magnesium, sodium or aluminum salts, but zinc salts are particularly preferred. Preferred metal salts of α,β-unsaturated organic acids are zinc diacrylate and zinc dimethacrylate, with zinc dimethacrylate being particularly preferred. The metal salts of α,β-unsaturated organic acids can be used alone or in combination of two or more.

The metal salt of an α,β-unsaturated organic acid is preferably It is used in the range of 0.5 to 30 parts by weight, more preferably 1 to 25 parts by weight, particularly preferably 2 to 20 parts by weight.

《Other polymers》
The composition of the present invention can further contain other polymers than components (A) and (D).
Examples of other polymers that require cross-linking 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 ( SEPS) and other styrene thermoplastic elastomers (TPS), olefin thermoplastic elastomers (TPO), vinyl chloride elastomers (TPVC), ester thermoplastic elastomers (TPC), amide thermoplastic elastomers (TPA), urethane thermal Elastomers such as thermoplastic elastomers (TPU) and other thermoplastic elastomers (TPZ) can be used.

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, relative to the total 100 parts by mass of component (A) and component (D). Part by mass or less.

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

One embodiment of the composition of the invention is prepared, for example, as follows. Component (A), carbon black (B), short fiber (C), component (D), and other predetermined components are put into a kneader and heated under predetermined conditions (for example, 80 to 200 ° C. for 3 to 30 minutes) to homogenize by kneading (A kneading). In addition, in the A kneading, no cross-linking agent or the like is added, which crosslinks the component (A) when heated to the heating temperature of the A kneading. The temperature of the mixture kneaded in A kneading is then lowered to below the cross-linking temperature of the cross-linking agent (for example, 130 ° C. or less), and then the cross-linking agent or the like that was not added in A kneading is added to the mixture, and the predetermined The composition of the present invention can be obtained by further kneading and homogenizing (B kneading) under heating conditions (for example, roll temperature of 30 to 80° C. for 1 to 30 minutes).

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 qualities 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. Also, this cross-linking reaction can be carried out in the air.

In the present invention, the (crosslinked) molded article can be suitably used as a constituent member of a power transmission belt. For example, the composition of the present invention has high adhesive strength and green 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 components for power transmission belts that are excellent in 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 transmission belt of the present invention include friction transmission belts such as V-belts and V-ribbed belts; and engagement transmission belts such as timing belts. Power transmission belts are, for example, power transmission belts for automobiles, power transmission belts for motorcycles, and power transmission belts for general industrial machinery. V-belts include, for example, wrapped belts and raw edge belts.

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

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

EXAMPLES The present invention will be described in more detail below based on examples, but the present invention is not limited to these examples. "Parts" means "parts by mass" unless otherwise specified.
[Physical properties of ethylene/α-olefin/non-conjugated polyene copolymer]
<Molar amounts of structural units derived from ethylene, structural units derived from α-olefins, and structural units derived from non-conjugated polyene>
Said molar amounts were determined by intensity measurements with 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 according to JIS K6300 (1994) using a Mooney viscometer (Model SMV202 manufactured by Shimadzu Corporation).

<B value>
Using o-dichlorobenzene-d ₄ /benzene-d ₆ (4/1 [v/v]) as a measurement solvent, 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 x [E] x ([X] + [Y])] (i)
Here, [E], [X] and [Y] are respectively ethylene [A1], α-olefins having 4 to 20 carbon atoms [A2], and non-conjugated polyene [A3]. [EX] indicates the diad chain fraction of ethylene [A1]-α-olefin having 4 to 20 carbon atoms [A2].

[Ethylene/α-olefin/non-conjugated polyene copolymer (A)]
(1) An ethylene/1-butene/5-ethylidene-2-norbornene (ENB) copolymer having the following physical properties was obtained according to the description in [Synthesis Example C1] of WO 2015/122415. 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°C: 30
Mooney viscosity ML ₍₁₊₄₎ 125°C: 22
B value: 1.3

(2) An ethylene/1-butene/5-ethylidene-2-norbornene (ENB) copolymer having the following physical properties was obtained according to the description in [Synthesis Example C1] of WO 2015/122415. Hereinafter, this will be referred to as "EBDM-2".
The structure and physical properties of EBDM-2 are as follows.
Structural unit derived from ethylene: 67.8 mol%
Structural unit derived from 1-butene: 30.7 mol%
Structural unit derived from ENB: 1.5 mol%
Mooney viscosity ML ₍₁₊₄₎ 100°C: 70
Mooney viscosity ML ₍₁₊₄₎ 125°C: 50
B value: 1.3

[Ethylene/α-olefin copolymer (D)]
(1) Ethylene/1-butene copolymer (hereinafter referred to as “EBR-1”)
Density: 862 kg/m ³ , Melting point: <50°C, MFR: 1.2 g/10 min [Mitsui Chemicals Co., Ltd., trade name TAFMER (registered trademark) DF610].
(2) Ethylene/1-butene copolymer (hereinafter referred to as “EBR-2”)
Density: 864 kg/m ³ , Melting point: <50°C, MFR: 3.6 g/10 min [Mitsui Chemicals Co., Ltd., trade name TAFMER (registered trademark) DF640].

[Example 1]
Using MIXTRON BB MIXER (manufactured by Kobe Steel, Ltd., BB-2 type, volume 1.7 L, rotor 2WH), 80 parts of EBDM-1 and 20 parts of EBR-1 were mixed with FN-66 as staple fibers. 15 parts of -3 (nylon staple fiber, 3 mm), 3 parts of ZnO # 1 / zinc oxide type 2 (JIS standard (K-1410)) as a crosslinking aid and 3 parts of MgO # 150, stearin as a processing aid 0.5 parts of acid, 100 parts of Asahi #60UG as carbon black, and 14 parts of Diana process oil PW-380 (paraffinic process oil) as a softening agent were blended and then kneaded to obtain compound 1. Ta.

The kneading conditions for the preparation of Compound 1 were a rotor speed of 40 rpm, a floating weight pressure of 3 kg/cm ² , a kneading time of 5 minutes, and a kneading discharge temperature of 144°C.

Next, after confirming that the temperature of compound 1 reached 40 ° C., using a 6-inch roll, 7 parts of zinc methacrylate (ZMA) and perhexa 25B-40 [2, 5-Dimethyl-2,5-di-(tert-butylperoxy)hexane] was added in a compounding amount of 7 parts and kneaded to obtain a compound 2.

The kneading conditions for the preparation of compound 2 were: 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. to obtain compound 2.

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

[Examples 2-3 and Comparative Examples 1-2]
Same as Example 1 except based on the composition and curing system described in Table 2.
Materials used in Examples and Comparative Examples are shown in Table 1 below.

[Unvulcanized physical property test; composition viscosity]
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).

[Unvulcanized physical property test; vulcanization rate]
Using compound 2, the vulcanization rate (tc90) was measured as follows with a measuring device: MDR2000P (manufactured by ALPHA TECHNOLOGIES) under the measurement conditions of a temperature of 170° C. and a time of 30 minutes.
The torque change obtained under conditions of constant temperature and constant shear rate was measured. The difference between the minimum value S'min [dNm] and the maximum value S'max [dNm] of the torque: S'max - S'min [dNm], the torque is 1 [dNm after the torque of the measurement sample reaches the minimum value S'min ] Time when it rises: TS1 [min], time when the torque of the measurement sample reaches 90% when the minimum value S'min of the torque is 0% and the maximum value S'max is 100% [min]: tc90 and MCR [dNm/min] were determined.

[Unvulcanized physical property test; green strength (GS; 10 ° C.)]
Compound 2 is press-molded at 150° C. for 3 minutes using a 3 mm-thick mold, and further press-molded at 50° C. for 120 minutes using a 2-mm-thick mold to obtain an unvulcanized sheet with a thickness of 2 mm. Ta. The obtained unvulcanized sheet was subjected to a tensile test according to JIS K6251 under the conditions of a measurement temperature of 23° C. and a tensile speed _{of 500} mm/min. (T _B ) and elongation at break (E _B ) were measured.

[Unvulcanized physical property test; probe tack test]
Probe tack was measured for Formulation 2 using TAC-II manufactured by RHESCA in accordance with JIS Z3284. Conditions were temperature 23° C. and 40° C., immersion speed: 120 mm/min, preload: 600 gf, test speed: 120 mm/min, press time: 60 s.

[Hardness test (Durometer-A)]
Flat portions of the 2 mm-thick crosslinked sheets were overlapped to form a 12 mm-thick sheet, and 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) is prepared by punching the crosslinked sheet with a thickness of 2 mm, and this test piece is used to measure 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 to measure the 25% modulus (M ₂₅ ), tensile stress at break (T _B ) and tensile elongation at break (E _B ).

[Tear strength]
A test piece having a size of 150 mm×50 mm was cut out from the crosslinked sheet having a thickness of 2 mm. Next, a 75 mm-long slit (cut) was made in the center of the test piece in the longitudinal direction, and the trouser tear strength was measured using a tensile tester (tensile speed: 200 mm/min, ambient temperature for measurement: 23°C). The tear strength was obtained by dividing the tear strength (N) by the sheet thickness (mm). The test was performed 3 times and the average value was adopted.

[Heat resistance test (heat aging resistance test)]
A heat aging test in which the crosslinked sheet having a thickness of 2 mm was kept at 140° C. for 72 hours was performed according to JIS K6257. The hardness, M ₂₅ , T _B and E _B of the sheet after the heat aging test were measured in the same manner as in the items of hardness test and tensile test.

As is clear from the above results, in Examples 1 to 3, compared with Comparative Examples 1 to 3, the viscosity suitable for molding processability, adhesiveness and green strength were well balanced. In particular, an unexpected result was the improvement in both probe tack and green strength.

Claims (9)

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], the following (1) 40 to 90 parts by mass of an ethylene/α-olefin/non-conjugated polyene copolymer (A) that satisfies the requirements of (3);
0.1 to 200 parts by mass of carbon black (B);
0.1 to 100 parts by mass of short fibers (C);
Contains 10 to 60 parts by mass of an ethylene/α-olefin copolymer (D) having a structural unit derived from ethylene and a structural unit derived from an α-olefin having 3 to 20 carbon atoms (provided that component ( The total of A) and (D) is 100 parts by mass.) Transmission belt composition:
(1) The molar ratio [[A1]/[A2]] between 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 to 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%. is mol %;
(3) The B value represented by the following formula (i) is 1.20 or more.
B value = ([EX] + 2 [Y]) / [2 x [E] x ([X] + [Y])] (i)
[Here, [E], [X] and [Y] are respectively moles of structural units derived from ethylene [A1], α-olefins having 4 to 20 carbon atoms [A2], and non-conjugated polyene [A3] [EX] indicates ethylene [A1]-C4-C20 α-olefin [A2] diad chain fraction. ] 2. The transmission belt composition according to claim 1, wherein the structural unit derived from the α-olefin [A2] having 4 to 20 carbon atoms in the copolymer (A) contains a structural unit derived from 1-butene. The composition for power transmission belts according to claim 1 or 2, wherein the short fibers (C) are aramid fibers. The transmission belt composition according to any one of claims 1 to 3, wherein the ethylene/α-olefin/non-conjugated polyene copolymer (A) further satisfies the following requirement (4):
(4) Mooney viscosity ML at 100°C ₍₁₊₄₎ 100°C is 5 to 150; The transmission belt composition according to any one of claims 1 to 4, further comprising a cross-linking aid having two or more ethylenic double bonds. The transmission belt composition according to any one of claims 1 to 5, wherein the ethylene/α-olefin copolymer (D) is an ethylene/1-butene copolymer. A molded article formed from the power transmission belt composition according to any one of claims 1 to 6. A crosslinked molded article formed from the power transmission belt composition according to any one of claims 1 to 6. A transmission belt comprising the molded article according to claim 7 or the crosslinked molded article according to claim 8.