JP6897144B2 - Rubber composition for conveyor belts, conveyor belts and belt conveyors - Google Patents

Description

The present invention relates to a rubber composition for a conveyor belt, a conveyor belt and a belt conveyor.

Belts of conveyors used for transporting materials and the like (conveyor belts) are required to have various characteristics such as cut resistance (difficulty of breaking when a sharp object collides) and gouging resistance. Here, gouging refers to a phenomenon in which the conveyor belt is scraped when rocks or the like fall on the conveyor belt.

As a rubber composition used for such a conveyor belt, for example, Patent Document 1 discloses a rubber composition for a conveyor belt containing natural rubber (NR) and styrene-butadiene rubber (SBR).

Japanese Unexamined Patent Publication No. 2014-205789

In recent years, with the increase in transportation volume and the like, it is required to further improve the cut resistance and gouging resistance of the conveyor belt.
Under these circumstances, the present inventors examined a rubber composition for a conveyor belt containing natural rubber and SBR with reference to the examples of Patent Document 1, and found that the cut resistance and gouging resistance were at a relatively high level. However, it became clear that further improvement is desired in consideration of future improvements in the required level.

Therefore, in view of the above circumstances, the present invention provides a rubber composition for a conveyor belt having excellent cut resistance and gouging resistance, a conveyor belt formed by using the rubber composition for a conveyor belt, and the conveyor belt. It is an object of the present invention to provide a mounted belt conveyor.

As a result of diligent studies on the above-mentioned problems, the present inventors have set the content of the repeating unit derived from aromatic vinyl and the ratio of the vinyl structure in the repeating unit derived from the conjugated diene within a specific range. We have found that the above problems can be solved by using a vinyl-conjugated diene copolymer, and have arrived at the present invention.
That is, the present inventors have found that the above problems can be solved by the following configuration.

(1) Contains a diene-based rubber containing less than 50% by mass of an aromatic vinyl-conjugated diene copolymer,
The aromatic vinyl-conjugated diene copolymer has a content of repeating units derived from aromatic vinyl of more than 20% by mass, and the proportion of vinyl structure among the repeating units derived from conjugated diene is 8 mol% or less. There is a rubber composition for conveyor belts.
(2) The rubber composition for a conveyor belt according to (1) above, wherein the aromatic vinyl-conjugated diene copolymer has a glass transition temperature of −50 ° C. or lower.
(3) The rubber composition for a conveyor belt according to (1) or (2) above, wherein the aromatic vinyl-conjugated diene copolymer has a weight average molecular weight of 200,000 to 1,000,000.
(4) Any of the above (1) to (3), wherein the aromatic vinyl-conjugated diene copolymer has a ratio of 1,4-cis structure in 17 mol% or more of the repeating units derived from the conjugated diene. The rubber composition for a conveyor belt described in Diene.
(5) It has an upper surface cover rubber layer, a reinforcing layer, and a lower surface cover rubber layer.
A conveyor belt in which at least the upper surface cover rubber layer is formed by using the rubber composition for a conveyor belt according to any one of (1) to (4) above.
(6) A belt conveyor equipped with the conveyor belt according to (5) above.

As shown below, according to the present invention, a rubber composition for a conveyor belt having excellent cut resistance and gouging resistance, a conveyor belt formed by using the rubber composition for a conveyor belt, and the conveyor belt A mounted belt conveyor can be provided.

FIG. 1 is a cross-sectional view schematically showing an example of a preferred embodiment of the conveyor belt of the present invention.

Hereinafter, the rubber composition for a conveyor belt of the present invention, a conveyor belt formed by using the rubber composition for a conveyor belt, and a belt conveyor equipped with the conveyor belt will be described.
The numerical range represented by using "~" in the present specification means a range including the numerical values before and after "~" as the lower limit value and the upper limit value.

[I] Rubber Composition for Conveyor Belt The rubber composition for conveyor belt of the present invention (hereinafter, also referred to as the composition of the present invention) is a diene-based rubber containing less than 50% by mass of an aromatic vinyl-conjugated diene copolymer. contains.
Here, the aromatic vinyl-conjugated diene copolymer has a content of a repeating unit derived from aromatic vinyl of more than 20% by mass, and the proportion of the vinyl structure in the repeating unit derived from the conjugated diene is 8 mol. % Or less.
Since the composition of the present invention has such a structure, it is considered to be excellent in cut resistance and gouging resistance. Although the reason is not clear, the aromatic vinyl-conjugated diene copolymer (hereinafter, also referred to as "specific copolymer") has a flexible structure having a low glass transition temperature because the proportion of the vinyl structure is extremely low. Therefore, it is considered that it exhibits excellent cut resistance and gouging resistance when it is used as a conveyor belt.

Hereinafter, the diene-based rubber contained in the composition of the present invention and optional components that can be contained in the composition of the present invention will be described.

[1] Diene-based rubber The diene-based rubber contained in the composition of the present invention contains less than 50% by mass of a specific aromatic vinyl-conjugated diene copolymer (specific copolymer) described later.
For the reason that the effect of the present invention is more excellent, the content of the specific copolymer in the diene rubber is preferably 40% by mass or less. The lower limit is not particularly limited, but is preferably 10% by mass or more, more preferably 20% by mass or more, for the reason that the effect of the present invention is more excellent.

[Specific copolymer]
The specific copolymer is an aromatic vinyl-conjugated diene copolymer (a copolymer of aromatic vinyl and a conjugated diene). Here, the content of the repeating unit derived from the aromatic vinyl is more than 20% by mass. Further, the proportion of the vinyl structure in the repeating unit derived from the conjugated diene is 8 mol% or less.
The specific copolymer is preferably a solution-polymerized copolymer (particularly, solution-polymerized SBR) because the effect of the present invention is more excellent.

〔monomer〕
The specific copolymer is a copolymer of aromatic vinyl and conjugated diene. That is, the specific copolymer is a copolymer obtained by copolymerizing aromatic vinyl and conjugated diene. The specific copolymer may be a copolymer obtained by copolymerizing another monomer in addition to the aromatic vinyl and the conjugated diene.

(1) Aromatic vinyl The above aromatic vinyl is not particularly limited, and for example, styrene, α-methylstyrene, 2-methylstyrene, 3-methylstyrene, 4-methylstyrene, 2-ethylstyrene, 3-ethylstyrene, 4-Ethylstyrene, 2,4-diisopropylstyrene, 2,4-dimethylstyrene, 4-t-butylstyrene, 5-t-butyl-2-methylstyrene, vinylnaphthalene, dimethylaminomethylstyrene, and dimethylaminoethylstyrene. And so on. Among these, styrene, α-methylstyrene, and 4-methylstyrene are preferable, and styrene is more preferable, because the effect of the present invention is more excellent. These aromatic vinyls can be used alone or in combination of two or more.

The content of the repeating unit derived from aromatic vinyl in the specific copolymer (hereinafter, also referred to as “aromatic vinyl content”) is more than 20% by mass. Among them, for the reason that the effect of the present invention is more excellent, it is preferably 21 to 50% by mass, more preferably 22 to 40% by mass, and further preferably 23 to 30% by mass.

(2) Conjugated Diene The conjugated diene is not particularly limited, and examples thereof include butadiene (for example, 1,3-butadiene), isoprene, and chloroprene. Of these, 1,3-butadiene and isoprene are preferable because the effects of the present invention are more excellent. These conjugated diene can be used alone or in combination of two or more.

The content of the repeating unit derived from the conjugated diene in the specific copolymer is preferably 30% by mass or more, more preferably 50% by mass or more, and more preferably 70% by mass or more, for the reason that the effect of the present invention is more excellent. It is more preferably mass% or more. The upper limit is not particularly limited, but for the reason that the effect of the present invention is more excellent, it is preferably less than 80% by mass, and more preferably 75% by mass or less.

(3) Other Monomers As described above, the specific copolymer may be a copolymer obtained by copolymerizing another monomer in addition to aromatic vinyl and conjugated diene. Such monomers include α, β-unsaturated nitriles such as acrylonitrile and methacrylonitrile; unsaturated carboxylic acids or acid anhydrides such as acrylic acid, methacrylic acid, and maleic anhydride; methyl methacrylate, acrylic acid. Unsaturated carboxylic acid esters such as ethyl and butyl acrylate; unconjugated diene such as 1,5-hexadiene, 1,6-heptadiene, 1,7-octadien, dicyclopentadiene, and 5-ethylidene-2-norbornene. And so on.

[Micro structure]
(1) Vinyl Structure In the specific copolymer, the proportion of the vinyl structure (hereinafter, also simply referred to as “the proportion of the vinyl structure”) among the repeating units derived from the conjugated diene is 8 mol% or less. Among them, for the reason that the effect of the present invention is more excellent, it is preferably 7 mol% or less, more preferably 6 mol% or less, and further preferably 5 mol% or less. The lower limit is not particularly limited and is 0 mol%.
Here, the ratio of the vinyl structure means that among all the repeating units derived from the conjugated diene, the repeating unit having a vinyl structure (for example, 1,2-vinyl structure when the conjugated diene is 1,3-butadiene) is used. It refers to the percentage (mol%) that it occupies.

(2) 1,4-Trans structure In the specific copolymer, the ratio of the 1,4-trans structure among the repeating units derived from the conjugated diene (hereinafter, also simply referred to as “the ratio of the 1,4-trans structure”). Is not particularly limited, but is preferably 75 mol% or less for the reason that the effect of the present invention is more excellent. Among them, for the reason that the effect of the present invention is more excellent, it is preferably 70 mol% or less, more preferably less than 70 mol%, and further preferably 60 mol% or less. The lower limit is not particularly limited, but for the reason that the effect of the present invention is more excellent, it is preferably 10 mol% or more, more preferably 20 mol% or more, and further preferably 30 mol% or more.
Here, the ratio of the 1,4-trans structure means the ratio (mol%) of the repeating units having the 1,4-trans structure among all the repeating units derived from the conjugated diene.

(3) 1,4-cis structure In the specific copolymer, the ratio of the 1,4-cis structure among the repeating units derived from the conjugated diene (hereinafter, also simply referred to as “the ratio of the 1,4-cis structure”). Is not particularly limited, but is preferably 10 to 92 mol%, more preferably 17 to 90 mol%. Among them, for the reason that the effect of the present invention is more excellent, it is preferably 20 to 88 mol%, more preferably 25 to 85 mol%, further preferably 30 to 80 mol%, and 40 to 80 mol%. It is particularly preferably 75 mol%.
Here, the ratio of the 1,4-cis structure means the ratio (mol%) of the repeating units having the 1,4-cis structure to all the repeating units derived from the conjugated diene.

Hereinafter, among the repeating units derived from the conjugated diene, "the ratio of vinyl structure (mol%), the ratio of 1,4-trans structure (mol%), and the ratio of 1,4-cis structure (mol%)" will be referred to. Also referred to as "vinyl / trans / cis".
Further, since the repeating unit derived from the conjugated diene comprises a vinyl structure, a 1,4-trans structure and a 1,4-cis structure, the total ratio (mol%) of each structure is 100 mol%.

〔Glass-transition temperature〕
The glass transition temperature (Tg) of the specific copolymer is not particularly limited, but is preferably −50 ° C. or lower, more preferably −60 ° C. or lower, for the reason that the effect of the present invention is more excellent. Among them, the temperature is preferably −70 ° C. or lower, more preferably −80 ° C. or lower, for the reason that the effect of the present invention is more excellent. The lower limit is not particularly limited, but it is preferably −100 ° C. or higher, and more preferably −90 ° C. or higher, for the reason that the effect of the present invention is more excellent.
In the present specification, the glass transition temperature (Tg) is measured at a heating rate of 20 ° C./min using a differential scanning calorimeter (DSC) and calculated by the midpoint method.

[Molecular weight]
The molecular weight of the specific copolymer is not particularly limited, but for the reason that the effect of the present invention is more excellent, the weight average molecular weight (Mw) is preferably 1,000 to 1,000,000, and 2,000 to 5, It is more preferably million, and even more preferably 3,000 to 2,000,000. Further, for the reason that the effect of the present invention is more excellent, the number average molecular weight (Mn) is preferably 500 to 5,000,000, more preferably 1,000 to 2,500,000, 1. It is more preferably 500,000 to 1,000,000, and particularly preferably 200,000 to 1,000,000.
In the present specification, the number average molecular weight (Mn) and the weight average molecular weight (Mw) are standard polystyrene-equivalent values obtained by gel permeation chromatography (GPC) measurement under the following conditions.
・ Solvent: Tetrahydrofuran ・ Detector: RI detector

[Preferable mode]
A preferred embodiment of the specific copolymer is, for example, a group consisting of titanium halide, tin halide, cyclic silazane, alkoxysilane, epoxide, amine, ketone and a compound represented by the formula (N) described later, for example. Examples thereof include an embodiment modified with at least one modifier (hereinafter, also referred to as “specific modifier”) selected from the above. In the case of the above aspect, the effect of the present invention is more excellent.
When the specific modifier is titanium halide, tin halide or a compound represented by the formula (N) described later, it is presumed that the terminal of the specific copolymer interacts with carbon black, and the specific modifier is cyclic. When it is silazane, alkoxysilane or amine, the end of the specific copolymer is presumed to interact with silica, and when the specific modifier is epoxide or ketone, the end of the specific copolymer interacts with silica or carbon black. It is presumed that.
For the reason that the effect of the present invention is more excellent, the specific modifier is preferably cyclic silazane, alkoxysilane, or a compound represented by the formula (N) described later, and is represented by the formula (N) described later. More preferably, it is a compound.

<Specific denaturant>
Hereinafter, each specific denaturing agent will be described.

(1) Titanium Halogen Titanium halide is not particularly limited, and is, for example, TiCl ₃ , TiBr ₃ , Ti (OC ₂ H ₅ ) Cl ₂ , Ti (OC ₄ H ₉ ) Cl ₂ , TiCl ₄ , Ti (OC _2). Examples thereof include H ₅ ) Cl ₃ , Ti (OC ₄ H ₉ ) Cl _3. Among them, the reason why the effects of the present invention is more excellent, TiCl ₃ (titanium trichloro), preferably TiCl ₄ (titanium tetrachloride), titanium tetrachloride is more preferable.

(2) Tin Halogenate Tin halide is not particularly limited, and examples thereof include tin fluoride, tin chloride, tin bromide, tin iodide, and tin astatinate.

(3) Circular sirazan The cyclic sirazan is not particularly limited as long as it is a circular sirazan.
Here, silazane is intended to be a compound having a structure in which a silicon atom and a nitrogen atom are directly bonded (a compound having a Si—N bond).
The cyclic silazane is preferably a compound represented by the following formula (S) for the reason that the effect of the present invention is more excellent.

In the above formula (S), R _{1 to} R ₃ independently represent a hydrogen atom or a substituent. Specific examples of the substituent are the same as R in the formula (P) described later.
R ₁ has an alkyl group (preferably 1 to 10 carbon atoms), an alkylsilyl group (preferably 1 to 10 carbon atoms), and an aromatic hydrocarbon group (preferably 1 to 10 carbon atoms) because the effect of the present invention is more excellent. The number of carbon atoms is preferably 6 to 18).
R ₂ is preferably an alkoxy group (preferably having 1 to 10 carbon atoms) because the effect of the present invention is more excellent.
In the above formula (S), L represents a divalent organic group.
Examples of the divalent organic group include a substituted or unsubstituted aliphatic hydrocarbon group (for example, an alkylene group, preferably 1 to 8 carbon atoms) and a substituted or unsubstituted aromatic hydrocarbon group (for example, an arylene group). Preferably 6 to 12 carbon atoms), _{-O-, -S-, -SO 2-} , -N (R)-(R: alkyl group), -CO-, -NH-, -COO-, -CONH -, or a group comprising a combination thereof (e.g., alkyleneoxy group (-C _m H _{2m O-:} m is a positive integer), alkyleneoxy carbonyl group, an alkylene carbonyl group) and the like.
L is preferably an alkylene group (preferably 1 to 10 carbon atoms) for the reason that the effect of the present invention is more excellent.

Examples of the compound represented by the above formula (S) include Nn-butyl-1,1-dimethoxy-2-azasilacyclopentane and N-phenyl-1,1-dimethoxy-2-azasilacyclopentane. , N-Trimethylsilyl-1,1-dimethoxy-2-azasilacyclopentane, N-trimethylsilyl-1,1-diethoxy-2-azasilacyclopentane and the like.
The silicon atom of cyclic silazane is considered to exhibit electrophilicity.

(4) Alkoxysilane The alkoxysilane is not particularly limited as long as it is a compound having an alkoxysilyl group, and is, for example, tetramethoxysilane, methyltrimethoxysilane, dimethyldimethoxysilane, tetraethoxysilane, methyltriethoxysilane, and dimethyldiethoxy. Silane, phenyltrimethoxysilane, diphenyldimethoxysilane, phenyltriethoxysilane, diphenyldiethoxysilane, hexyltrimethoxysilane, hexyltriethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane , 3-glycidoxypropylmethyldimethoxysilane, N, N-bistrimethylsilyl-3-aminopropyltrimethoxysilane, N, N-bistrimethylsilyl-3-aminopropyltriethoxysilane and the like.
The number of alkoxy groups in the alkoxysilyl group is not particularly limited, but is preferably two or more for the reason that the effect of the present invention is more excellent.
The silicon atom of alkoxysilane is considered to exhibit electrophilicity.

(5) Epoxide The epoxide is not particularly limited as long as it is a compound having an oxacyclopropane (oxylane) structure.
Specific examples of epoxides include ethylene oxide, propylene oxide, butylene oxide, cyclohexene oxide, styrene oxide, 1-phenylpropylene oxide, methylglycidyl ether, ethyl glucidyl ether, glycidyl isopropyl ether, butyl glycidyl ether, 1-methoxy-2-. Methyl propylene oxide, allyl glycidyl ether, 2-ethyloxyl glycidyl ether, phenyl glycidyl ether, p-tert-butyl phenyl glycidyl ether, lauryl alcohol glycidyl ether, stearyl glycidyl ether, palmityl glycidyl ether, myristyl glycidyl ether, lauryl glycidyl ether, Examples thereof include capryl glycidyl ether and caproyl glycidyl ether.

(6) Amine Amine is _{not particularly limited as long as it is a compound having an amino group (-NR 2} : R represents a hydrogen atom or a hydrocarbon group. The two Rs may be the same or different). .. Of these, aziridine is preferable because the effect of the present invention is more excellent. Examples of the aziridine include N-methyl aziridine, N-ethyl aziridine, N-isopropyl aziridine, N-phenyl aziridine, N- (4-methylphenyl) aziridine, N-methyl-2-methyl aziridine and the like.

(7) Ketone The ketone is not particularly limited as long as it is a compound having a ketone group (-CO-).
Specific examples of the ketone include acetone, benzophenone, and derivatives thereof.
Derivatives of benzoquinone include N, N, N', N'-tetramethyl-4,4'-diaminobenzoquinone, N, N, N', N'-tetraethyl (4,4'-diamino) -benzophenone, N. , N-dimethyl-1-aminobenzoquinone, N, N, N', N'-tetramethyl-1,3-diaminobenzoquinone, N, N-dimethyl-1-aminoanthraquinone, N, N, N', N' -Tetramethyl-1,4-diaminoanthraquinone, 4,4'-diacetylbenzoquinone and the like can be mentioned.

(8) Compound represented by the formula (N) Hereinafter, the compound represented by the following formula (N) will be described.

In the above formula (N), R ¹ represents a hydrogen atom or an alkyl group (preferably 1 to 10 carbon atoms), and R ² represents an alkylene group (preferably 2 to 10 carbon atoms).

Specific examples of the compound represented by the above formula (N) include N-methylpyrrolidone (in the above formula (N), R ₁ is a methyl group and R ₂ is a propylene group).

[Method for producing specific copolymer]
The method for producing the above-mentioned specific copolymer is not particularly limited, and a conventionally known method can be used. The method for setting the aromatic vinyl content, the ratio of the microstructure, the glass transition temperature, and the molecular weight within a specific range is not particularly limited, and for example, the type of the monomer to be polymerized, the amount ratio of the monomer, the type of the initiator, and the initiation. Examples thereof include a method of adjusting the amount ratio of the agent and the reaction temperature.

[Preferable mode]
As a preferred embodiment of the method for producing the specific copolymer, for example, an initiator prepared using an organic lithium compound, alkylaluminum and metal alcoholate (hereinafter, also referred to as “specific initiator”) is used for aromatics. Examples thereof include a method of copolymerizing a monomer containing vinyl and a diene (hereinafter, also referred to as “the method of the present invention”). When the above method is used, the composition of the present invention containing the obtained specific copolymer exhibits more excellent cut resistance and gouging resistance.

<Specific initiator>
As described above, in the method of the present invention, an initiator (specific initiator) prepared using an organic lithium compound, alkylaluminum and metallic alcoholate is used. Since the specific initiator is used in the method of the present invention, it is considered that the ratio of the vinyl structure to the repeating units derived from diene is suppressed (for example, 8 mol% or less) in the obtained specific copolymer. ..

The specific initiator is preferably one using aromatic divinyl for the reason that the effect of the present invention is more excellent. That is, it is preferably prepared using an organic lithium compound, alkylaluminum, metallic alcoholate and aromatic divinyl. By using aromatic divinyl, the obtained copolymer becomes branched, the molecular weight increases, and the cut resistance and gouging resistance are further improved.

(1) Organolithium Compound Examples of the organolithium compound include monoorganolithium compounds such as n-butyllithium, sec-butyllithium, tert-butyllithium, n-propyllithium, iso-propyllithium, and benzyllithium; 4-dilithiobutane, 1,5-dilithiopentane, 1,6-dilithiohexane, 1,10-dilithiodecane, 1,1-dilithiodiphenylene, dilithiopolybutadiene, dilithiopolyisoprene, 1,4-dilithiobenzene, 1,2-Dilithio-1,2-diphenylethane, 1,4-dilithio-2-ethylcyclohexane, 1,3,5-trilithiobenzene, 1,3,5-trilithio-2,4,6-triethylbenzene Examples thereof include polyfunctional organolithium compounds such as. In particular, monoorganolithium compounds such as n-butyllithium, sec-butyllithium, and tert-butyllithium are preferable because the effects of the present invention are more excellent.

The amount of the organolithium compound used in the preparation of the specific initiator is not particularly limited, but is preferably 0.001 to 10 mol% with respect to the monomer to be polymerized for the reason that the effect of the present invention is more excellent.

(2) Alkyl Aluminum Alkyl aluminum is not particularly limited as long as it is a compound in which an alkyl group (chain, branched, cyclic) is bonded to an aluminum atom (Al). The number of carbon atoms of the alkyl group is not particularly limited, but it is preferably 1 to 20 and more preferably 1 to 10 for the reason that the effect of the present invention is more excellent. Specific examples of alkylaluminum include trimethylaluminum, triethylaluminum, triisopropylaluminum, tributylaluminum, triisobutylaluminum, tripropylaluminum, tributylaluminum, triisobutylaluminum, pentyldiethylaluminum, 2-methylpentyl-diethylaluminum, and dicyclohexylethyl. Aluminum, tripentyl aluminum, trihexyl aluminum, trioctyl aluminum, tri (2-ethylhexyl) aluminum, tricyclohexyl aluminum, tricyclopentyl aluminum, tri (2,2,4-trimethylpentyl) aluminum, tridodecyl aluminum, tri (2) -Methylpentyl) Aluminum, diisobutylaluminum hydride, diethylaluminum hydride, dipropylaluminum hydride, propylaluminum dihydride, isobutylaluminum dihydride, etc. Among them, trioctylaluminum is used because the effect of the present invention is more excellent. preferable.

The ratio of alkylaluminum to the organolithium compound used in the preparation of the specific initiator is not particularly limited, but is preferably 0.1 to 50 molar equivalents, preferably 0.5 to 50 molar equivalents, for reasons of greater efficacy of the present invention. More preferably, it is 10 molar equivalents. Here, 1 mol equivalent means the amount when 1 mol of alkylaluminum is added when 1 mol of the organic lithium compound is used. That is, the ratio of alkylaluminum to the organic lithium compound used in the preparation of the specific initiator is not particularly limited, but is preferably 10 to 5000 mol%, preferably 50 to 1000 mol%, for the reason that the effect of the present invention is more excellent. More preferably.

(3) Metal Alkoxide The metal alcoholate (metal alkoxide) is not particularly limited as long as it is a compound in which the hydrogen of the hydroxy group of the alcohol is replaced with a metal.
The metal is not particularly limited, and examples thereof include alkali metals, alkaline earth metals, transition metals (metals of groups 3 to 11), aluminum, germanium, tin, and antimony. Among them, alkaline earth metals are preferable, and barium is more preferable, because the effect of the present invention is more excellent.
The alcohol is not particularly limited as long as it is a compound in which a hydrogen atom of a chain, branched or cyclic hydrocarbon is substituted with a hydroxy group. The carbon number of the alcohol is not particularly limited, but it is preferably 1 to 30 and more preferably 1 to 20 for the reason that the effect of the present invention is more excellent.

The metal alcoholate is preferably barium alcoholate (barium alkoxide) because the effect of the present invention is more excellent. Examples of the barium alkoxide include barium dimethoxydo, barium diethoxydo, barium dipropoxide, barium dibutoxide, barium bis (2-ethylhexoxide) and the like.

The ratio of the metal alcoholate to the organolithium compound used in the preparation of the specific initiator is not particularly limited, but is preferably 0.01 to 5 molar equivalents, preferably 0.1 to 5 molar equivalents, for the reason that the effect of the present invention is more excellent. More preferably, it is 3 molar equivalents. Here, 1 mol equivalent means the amount when 1 mol of the metal alcoholate is added when 1 mol of the organic lithium compound is used. That is, the ratio of the metal alcoholate to the organic lithium compound used in the preparation of the specific initiator is not particularly limited, but is preferably 1 to 500 mol%, preferably 10 to 300 mol%, for the reason that the effect of the present invention is more excellent. More preferably.

(4) Aromatic Divinyl The aromatic divinyl is not particularly limited as long as it is an aromatic compound having two vinyl groups. Of these, divinylbenzene is preferable because the effect of the present invention is more excellent.

The ratio of aromatic divinyl to the organolithium compound used in the preparation of the specific initiator is not particularly limited, but is preferably 0.1 to 5 molar equivalents, preferably 0.3, for the reason that the effect of the present invention is more excellent. More preferably, it is ~ 3 molar equivalents. Here, 1 mol equivalent means the amount when 1 mol of aromatic divinyl is added when 1 mol of the organolithium compound is used. That is, the ratio of aromatic divinyl to the organolithium compound used in the preparation of the specific initiator is not particularly limited, but is preferably 10 to 500 mol%, preferably 30 to 300, for the reason that the effect of the present invention is more excellent. More preferably, it is in mol%.

(Preparation method of specific initiator)
The method for preparing the specific initiator is not particularly limited, and examples thereof include a method in which the above-mentioned organic lithium compound, alkylaluminum, metal alcoholate and the like are dissolved in a solvent.
The type of solvent is not particularly limited, and for example, an organic solvent or the like can be used, but for the reason that the effect of the present invention is more excellent, it is preferable to use a solvent other than alcohol.

<Monomer>
The monomer (mixture) contains aromatic vinyl and diene. Specific examples and preferred embodiments of aromatic vinyl and diene are as described above.
The proportion of aromatic vinyl in the monomer is not particularly limited, but for the reason that the effect of the present invention is more excellent, it is preferably more than 20% by mass, preferably 21 to 50% by mass, and 22 to 40% by mass. Is more preferable, and 23 to 30% by mass is further preferable.
The ratio of diene in the monomer is not particularly limited, but for the reason that the effect of the present invention is more excellent, it is preferably 30% by mass or more, more preferably 50% by mass or more, and 70% by mass or more. It is more preferable to have. The upper limit is not particularly limited, but for the reason that the effect of the present invention is more excellent, it is preferably less than 80% by mass, and more preferably 75% by mass or less.
The monomer may contain yet another monomer in addition to the aromatic vinyl and diene. Specific examples of such monomers are the same as those of the "other monomers" described above.

<Polymer copolymerization>
As described above, in the method of the present invention, a monomer containing aromatic vinyl and diene is copolymerized using a specific initiator. The specific initiator and monomer are as described above.

The method of copolymerizing the monomers is not particularly limited, but a method of adding the above-mentioned monomer to the above-mentioned organic solvent solution containing the specific initiator and stirring in a temperature range of 0 to 120 ° C. (preferably 30 to 100 ° C.) and the like. Can be mentioned.

The ratio of the organolithium compound in the specific initiator to the monomer is not particularly limited, but is preferably 0.001 to 10 mol% for the reason that the effect of the present invention is more excellent.

When copolymerizing the monomers, a phenol compound or an amine compound may be added to the copolymerization system (for example, the organic solvent solution containing the above-mentioned specific initiator). Among them, a phenol compound is preferable because the effect of the present invention is more excellent. Addition of a phenolic compound increases the proportion of 1,4-cis structure in the resulting aromatic vinyl-diene copolymer among the repeating units derived from diene.
Here, the phenol compound is intended to be a compound having a phenolic hydroxyl group or a metal salt thereof. Further, the amine compound is intended to be a compound having an _{amino group (-NH 2} , -NHR, -NR _2). Here, R represents a substituent. Specific examples and preferred embodiments of the substituent are the same as R in the formula (P) described later. Two R a -NR ₂ can be the same or different.
Examples of the phenol compound include a compound represented by the following formula (P).

In the above formula (P), X ¹ represents a hydrogen atom or a metal atom. Examples of the metal atom include a sodium atom and a potassium atom.
In the above formula (P), R represents a hydrogen atom or a substituent. The plurality of Rs may be the same or different.
The above-mentioned substituent is not particularly limited as long as it is a monovalent substituent, and for example, a halogen atom, a hydroxy group, a nitro group, a carboxy group, an alkoxy group, an amino group, a mercapto group, an acyl group, an imide group and a phosphino group. , A phosphinyl group, a silyl group, a hydrocarbon group which may have a hetero atom, and the like.
Examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom.
Examples of the heteroatom of the hydrocarbon group which may have the heteroatom include an oxygen atom, a nitrogen atom, a sulfur atom and a phosphorus atom.
Examples of the hydrocarbon group which may have the heteroatom include an aliphatic hydrocarbon group, an aromatic hydrocarbon group, and a group in which these are combined.
The aliphatic hydrocarbon group may be linear, branched or cyclic. Specific examples of the aliphatic hydrocarbon group include a linear or branched alkyl group (particularly 1 to 30 carbon atoms), a linear or branched alkenyl group (particularly 2 to 30 carbon atoms), and the like. Examples thereof include a linear or branched alkynyl group (particularly, having 2 to 30 carbon atoms).
Examples of the aromatic hydrocarbon group include aromatic hydrocarbon groups having 6 to 18 carbon atoms such as a phenyl group, a tolyl group, a xsilyl group, and a naphthyl group.
In the above formula (P), X represents a hydrogen atom, ^one -OX group or a substituent. X ¹ is as described above. Moreover, the specific example of the substituent is the same as R in the above-mentioned formula (P).

The amount of the phenol compound to be added is not particularly limited, but is preferably 0.01 to 90 mol%, preferably 0.1 to 80 mol% with respect to the above-mentioned organolithium compound for the reason that the effect of the present invention is more excellent. More preferably.

The method for terminating the polymerization is not particularly limited, and examples thereof include a method of adding an alcohol (particularly methanol) to the polymerization solution.
The method for terminating the polymerization is selected from titanium halide, tin halide, cyclic silazane, alkoxysilane, epoxide, amine, ketone and a compound represented by the following formula (N) because the effect of the present invention is more excellent. A method of terminating the polymerization using an electrophile (hereinafter, also referred to as “specific electrophile”) is preferable.
That is, the method of the present invention is preferably a method of copolymerizing a monomer containing an aromatic vinyl and a diene using a specific initiator, and then terminating the polymerization using a specific electrophile.
The definition, specific examples and preferred embodiments of the specific electrophile are the same as those of the specific denaturant described above.
By terminating the polymerization with a specific electrophile, a copolymer having a terminal modified with a specific electrophile (specific modifier) can be obtained.
The amount of the specific electrophile with respect to the specific initiator is not particularly limited, but for the reason that the effect of the present invention is more excellent, the ratio of the electrophile to the organic lithium compound (specific electrophile / organic lithium compound) is a molar ratio. It is preferably 0.1 to 10, more preferably 1 to 5.
For the reason that the effect of the present invention is more excellent, the ratio of the specific electrophile to the alkylaluminum (alkylAl) (specific electrophile / alkylAl) is preferably 0.1 to 10 in terms of molar ratio, and 1 to 1 It is more preferably 5.
For the reason that the effect of the present invention is more excellent, the ratio of the electrophile to the metal alcoholate (electrophile / metal alcoholate) is preferably 0.1 to 20 and more preferably 1 to 10 in terms of molar ratio. preferable.

[Other rubber components]
The diene-based rubber may contain other rubber components other than the specific copolymer. Examples of such other rubber components include natural rubber (NR), isoprene rubber (IR), butadiene rubber (BR), styrene-butadiene rubber other than the specified copolymer (SBR), and acrylonitrile-butadiene copolymer rubber (NBR). , Butyl rubber (IIR), halogenated butyl rubber (Br-IIR, Cl-IIR), chloroprene rubber (CR) and the like. Of these, natural rubber (NR) is preferable because the effect of the present invention is more excellent.
The content of other rubber components (for example, natural rubber) in the diene rubber is not particularly limited, but is preferably 50% by mass or more, preferably more than 50% by mass, for the reason that the effect of the present invention is more excellent. More preferably, it is more preferably 60% by mass or more. The upper limit is not particularly limited, but is preferably 90% by mass or less for the reason that the effect of the present invention is more excellent.

[2] Optional components In addition to the above-mentioned components, the composition of the present invention contains carbon black, silica, a silane coupling agent, a vulcanizing agent, a vulcanization accelerator, a vulcanization aid, a vulcanization retarder, an oil, and the like. It may contain other components (arbitrary components) such as various compounding agents.

[Carbon black]
The composition of the present invention preferably contains carbon black for the reason that the effect of the present invention is more excellent.
Examples of carbon black include ISAF (Intermediate Super Abrasion Furnace), HAF (High Abrasion Furnace), SAF (Super Abrasion Furnace), FEF (Fast Extrusion Furnace Furnace Furnace Furnace Furnace Furnace Furnace Furnace Furnace Furnace Furnace Furnace Furnace Furnace Furnace Furnace Furnace Furnace Furnace Furnace Furnace Furnace Furnace Furnace Furnace Furnace Furnace Furnace Furnace Furnace Furnace Furnace Furnace Furnace Furnace , FT (Fine Thermal), MT (Medium Thermal) class and the like. Among them, ISAF class is preferable because the effect of the present invention is more excellent.

In the composition of the present invention, the content of carbon black is not particularly limited, but for the reason that the effect of the present invention is more excellent, it is preferably 20 to 80 parts by mass with respect to 100 parts by mass of the diene rubber. More preferably, it is ~ 70 parts by mass. One type of carbon black may be used alone, or two or more types may be used in combination.

[silica]
The composition of the present invention preferably contains silica for the reason that the effect of the present invention is more excellent.
The silica is not particularly limited, and examples thereof include fumed silica, calcined silica, precipitated silica, pulverized silica, molten silica, anhydrous fine powder silicic acid, hydrous fine powder silicic acid, hydrous aluminum silicate, and hydrous calcium silicate. These may be used alone or in combination of two or more.

In the composition of the present invention, the content of silica is not particularly limited, but for the reason that the effect of the present invention is more excellent, it is preferably 1 to 50 parts by mass, preferably 1 to 50 parts by mass with respect to 100 parts by mass of the diene rubber. More preferably, it is 20 parts by mass.

[Silane coupling agent]
The silane coupling agent is not particularly limited, but it is preferable to use a polysulfide-based silane coupling agent used for rubber applications.
Specific examples of the polysulfide-based silane coupling agent include bis (3-triethoxysilylpropyl) tetrasulfide and bis (3-triethoxysilylpropyl) disulfide.

[Vulcanizing agent]
The composition of the present invention preferably contains a vulcanizing agent for the reason that the effect of the present invention is more excellent.
The vulcanizing agent is not particularly limited, and examples thereof include vulcanizing agents such as sulfur, organic peroxide-based, metal oxide-based, disulfide-based, phenol resin, and quinonedioxime.
Examples of sulfur include powdered sulfur, precipitated sulfur, highly dispersible sulfur, surface-treated sulfur, insoluble sulfur, dimorphophosphorindisulfide, and alkylphenol disulfide.
Specific examples of the organic peroxide-based vulcanizing agent include benzoyl peroxide, t-butyl hydroperoxide, 2,4-dichlorobenzoyl peroxide, and 2,5-dimethyl-2,5-di. Examples thereof include (t-butylperoxy) hexane and 2,5-dimethylhexane-2,5-di (peroxylbenzoate).
Other examples include magnesium oxide, litharge, p-quinone dioxime, p-dibenzoylquinone dioxime, poly-p-dinitrosobenzene, methylene dianiline and the like.

[Vulcanization accelerator]
The composition of the present invention preferably contains a vulcanization accelerator for the reason that the effect of the present invention is more excellent.
Examples of the vulcanization accelerator include vulcanization accelerators such as thiuram-based, aldehyde / ammonia-based, guanidine-based, thiourea-based, thiazole-based, sulfenamide-based, and dithiocarbamate-based.

Examples of the thiuram-based sulfide accelerator include tetramethylthiuram monosulfide (TS), tetramethylthiuram disulfide (TMTD), dipentamethylene thiuram tetrasulfide and the like.

Specific examples of the aldehyde / ammonia-based vulcanization accelerator include hexamethylenetetramine (H) and the like.
Specific examples of the guanidine-based vulcanization accelerator include diphenylguanidine and the like.
Specific examples of the thiourea-based vulcanization accelerator include ethylene thiourea and the like.
Specific examples of the thiazole-based vulcanization accelerator include dibenzothiazyl disulfide (DM), 2-mercaptobenzothiazole, and a zinc salt thereof.
Specific examples of the sulfenamide-based vulcanization accelerator include N-cyclohexyl-2-benzothiazolyl sulfenamide (CZ) and Nt-butyl-2-benzothiazolyl sulfenamide (NS). ) Etc. can be mentioned.
Specific examples of the dithiocarbamate-based vulcanization accelerator include Na-dimethyldithiocarbamate, Zn-dimethyldithiocarbamate, Te-diethyldithiocarbamate, Cu-dimethyldithiocarbamate, Fe-dimethyldithiocarbamate, and pipecholine. Examples include pipecholyl dithiocarbamate.
Of these, thiuram-based vulcanization accelerators and sulfenamide-based vulcanization accelerators are preferable.
The vulcanization accelerators can be used alone or in combination of two or more.
When two or more types of vulcanization accelerators are used, the content of the vulcanization accelerator is the total content of all the vulcanization accelerators.

[Vulcanization aid]
The composition of the present invention preferably contains a vulcanization aid for the reason that the effect of the present invention is more excellent.
As the vulcanization aid, a general rubber aid can be used in combination, and examples thereof include zinc oxide, stearic acid, oleic acid, and zinc salts thereof.

[Vulcanization retarder]
Specific examples of the sulfide retardant include organic acids such as phthalic anhydride, benzoic acid, salicylic acid, and acetylsalicylic acid; N-nitrosodiphenylamine, N-nitrosophenyl-β-naphthylamine, and N-nitroso-. Examples thereof include nitroso compounds such as polymers of trimethyl-dihydroquinoline; halides such as trichloromelanin; 2-mercaptobenzimidazole; Santogard PVI: and the like.

[Compounding agent]
Examples of the compounding agent include fillers other than the above-mentioned carbon black and silica, resins, antioxidants, oils, antioxidants, pigments (dye), plasticizers, rock-modifying agents, ultraviolet absorbers, flame retardants, and the like. Examples thereof include solvents, surfactants (including leveling agents), dispersants, dehydrating agents, rust preventives, adhesive imparting agents, antistatic agents, processing aids and the like.
As these compounding agents, general ones for rubber compositions can be used. The blending amount thereof is not particularly limited and can be arbitrarily selected.

[3] Method for Producing Rubber Composition for Conveyor Belt The method for producing the composition of the present invention is not particularly limited, and specific examples thereof include, for example, a known method and apparatus (for example, a Banbury mixer) for each of the above-mentioned components. , Kneader, roll, etc.), and kneading method. Among them, it is preferable to first mix the components other than the vulcanizing agent and the vulcanization accelerator at a high temperature (preferably 40 to 160 ° C.), cool the components, and then mix the vulcanizing agent and the vulcanization accelerator.
In addition, the composition of the present invention can be vulcanized or crosslinked under conventionally known vulcanization or crosslinking conditions.

[II] Conveyor Belt Next, the conveyor belt of the present invention will be described.
The conveyor belt of the present invention is a conveyor belt formed by using the above-mentioned rubber composition for a conveyor belt of the present invention.
The rubber composition used for the conveyor belt of the present invention is not particularly limited as long as it is the above-mentioned rubber composition for a conveyor belt of the present invention.

One of the preferred embodiments of the conveyor belt of the present invention is a conveyor belt having an upper surface cover rubber layer, a reinforcing layer and a lower surface cover rubber layer.
The number of layers constituting the top cover rubber layer may be one or more. It can be 2 or more. For example, there is a case where it has an outer layer as a surface for transporting a transported object and an inner layer as an adhesive layer. The same applies to the bottom cover rubber layer.
When the number of layers constituting the top cover rubber layer is plurality, the rubber compositions forming each layer of the top cover rubber layer may be the same or different. The same applies to the bottom cover rubber layer.
The conveyor belt of the present invention is preferably a conveyor belt formed by using at least the upper surface cover rubber layer of the above-mentioned rubber composition for a conveyor belt of the present invention.

Hereinafter, each layer will be described.

[1] Top Cover Rubber Layer As described above, one of the preferred embodiments is that the top cover rubber layer is formed by the rubber composition for a conveyor belt of the present invention. Further, it is preferable that at least the surface of the upper surface cover rubber layer is formed by the rubber composition for a conveyor belt of the present invention. When the upper surface cover rubber layer of the conveyor belt of the present invention is formed by the rubber composition for the conveyor belt of the present invention, the effect of the present invention is more excellent.
In the conveyor belt of the present invention, the thickness of the upper surface cover rubber layer is preferably 3 to 20 mm, more preferably 6 to 15 mm. Here, when the upper surface cover rubber layer is composed of a plurality of layers, the thickness of the upper surface cover rubber layer means the total thickness of these layers.

[2] Reinforcing layer The core body of the reinforcing layer is not particularly limited, and those used for ordinary conveyor belts can be appropriately selected and used. Specific examples include, for example, a cotton cloth and a synthetic fiber or a synthetic fiber coated with rubber glue and infiltrated, an RFL (Resorcin Formaldehyde) treated product folded, a special woven nylon canvas, and steel. Code etc. can be mentioned. The shape of the reinforcing layer is not particularly limited, and for example, a sheet-shaped or wire-shaped reinforcing wire may be embedded in parallel. The reinforcing layers can be used alone or in combination of two or more.

[3] Bottom Cover Rubber Layer One of the preferred embodiments is that the bottom cover rubber layer is composed of two or more layers. The rubber composition used to form the bottom cover rubber layer is not particularly limited. For example, conventionally known ones can be mentioned.

The conveyor belt of the present invention will be described below with reference to the accompanying drawings. The conveyor belt of the present invention is not limited to the drawings.

FIG. 1 is a cross-sectional view schematically showing an example of a preferred embodiment of the conveyor belt of the present invention. In FIG. 1, the conveyor belt 1 has a reinforcing layer 3 as a central layer, and an upper surface cover rubber layer 2 and a lower surface cover rubber layer 4 are provided on both sides of the reinforcing layer 3, and the upper surface cover rubber layer 2 is an outer layer 11 and an inner layer 12-2. It is composed of layers, and the lower surface cover rubber layer 4 is composed of two layers, an outer layer 16 and an inner layer 15. The conveyor belt 1 has a material transport surface 5.
At least one selected from the group consisting of the outer layer 11, the inner layer 12, the inner layer 15, and the outer layer 16 can be formed by the rubber composition for a conveyor belt of the present invention. It is preferable that at least one selected from the group consisting of the outer layer 11 and the inner layer 12 is formed by the rubber composition for a conveyor belt of the present invention, and it is more preferable that at least the outer layer 11 is formed by the rubber composition for a conveyor belt of the present invention. preferable.

[4] Conveyor Belt Manufacturing Method The conveyor belt manufacturing method of the present invention is not particularly limited, and a commonly used method or the like can be adopted. Specifically, for example, first, the raw materials for each cover rubber layer are kneaded using a roll, a kneader, a Banbury mixer or the like, and then molded into a sheet shape for each cover rubber layer using a calendar or the like, and then A method of laminating the obtained layers in a predetermined order so as to sandwich the reinforcing layer and pressurizing at a temperature of 150 to 170 ° C. for 10 to 60 minutes is preferably exemplified.

[III] Belt Conveyor The belt conveyor of the present invention is a belt conveyor equipped with the above-mentioned conveyor belt of the present invention.

Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited thereto.

[Synthesis example]
Comparative specific copolymers and specific copolymers 1 to 3 were synthesized as follows. Here, the specific copolymers 1 to 3 correspond to the above-mentioned specific copolymers. On the other hand, the comparative specific copolymer does not correspond to the above-mentioned specific copolymer because the aromatic vinyl content is 20% by mass or less.

<Comparative specific copolymer (unmodified SBR)>
n-BuLi (manufactured by Kanto Chemical Co., Ltd .: 1.60 mol / L (hexane solution), 18 mL, 28.8 mmol), bariumbis (2-ethylhexoxide) (Ba (OCH ₂ CH (C ₂ H ₅ ) CH ₂ CH) ₂ CH ₂ CH ₃ ) ₂ ) (STREM: 1M (toluene / hexane solution) 7.5 mL), trioctyl aluminum (Aldrich: 25 wt% (hexane solution), 45 mL) and cyclohexane (Kanto Kagaku: 10 mL) Of the initiator solution prepared using (corresponding to the specific initiator described above), 60 mL was prepared with 1,3-butadiene (877 g, 16,210 mmol), styrene (manufactured by Kanto Chemical Co., Ltd.: 199 g, 1,910 mmol) and 4 A mixture of -tert-butyllithiumatechol (3.17 g, 19.1 mmol) was added to a solution of cyclohexane (4.28 kg) and stirred at 60 ° C. for 14 hours. After cooling to room temperature, methanol (manufactured by Kanto Chemical Co., Inc .: 3.44 g) was added to terminate the polymerization. The resulting solution was removed and concentrated under reduced pressure. The concentrated solution was poured into methanol (5 L) to separate the methanol-insoluble component. As a result, a styrene-butadiene copolymer (unmodified SBR) (929 g, Mn = 250,000, Mw = 590,000, PDI = 2.4) was obtained in a yield of 87%. It was estimated by IR analysis that vinyl / trans / cis = 4/55/41. The aromatic vinyl content (content of the repeating unit derived from styrene) was 20% by mass, and the glass transition temperature was −89 ° C.

<Specific copolymer 1 (unmodified SBR)>
n-BuLi (manufactured by Kanto Chemical Co., Ltd .: 1.60 mol / L (hexane solution), 18 mL, 28.8 mmol), bariumbis (2-ethylhexoxide) (Ba (OCH ₂ CH (C ₂ H ₅ ) CH ₂ CH) ₂ CH ₂ CH ₃ ) ₂ ) (STREM: 1M (toluene / hexane solution) 7.5 mL), trioctyl aluminum (Aldrich: 25 wt% (hexane solution), 45 mL) and cyclohexane (Kanto Kagaku: 10 mL) Of the initiator solution prepared using (corresponding to the specific initiator described above), 60 mL was prepared with 1,3-butadiene (768 g, 14,200 mmol), styrene (Kanto Kagaku: 299 g, 2,870 mmol) and 4 A mixture of −tert-butyllithiumatechol (4.79 g, 28.8 mmol) was added to a solution of cyclohexane (4.24 kg) and stirred at 60 ° C. for 14 hours. After cooling to room temperature, methanol (manufactured by Kanto Chemical Co., Inc .: 3.44 g) was added to terminate the polymerization. The resulting solution was removed and concentrated under reduced pressure. The concentrated solution was poured into methanol (5 L) to separate the methanol-insoluble component. As a result, a styrene-butadiene copolymer (unmodified SBR) (979 g, Mn = 240,000, Mw = 680,000, PDI = 2.8) was obtained in a yield of 92%. It was estimated by IR analysis that vinyl / trans / cis = 5/51/44. The aromatic vinyl content (content of the repeating unit derived from styrene) was 29% by mass, and the glass transition temperature was −84 ° C.

<Specific copolymer 2 (NMP end-modified SBR)>
n-BuLi (manufactured by Kanto Chemical Co., Ltd .: 1.60 mol / L (hexane solution), 18 mL, 28.8 mmol), bariumbis (2-ethylhexoxide) (Ba (OCH ₂ CH (C ₂ H ₅ ) CH ₂ CH) ₂ CH ₂ CH ₃ ) ₂ ) (STREM: 1M (toluene / hexane solution) 7.5 mL), trioctyl aluminum (Aldrich: 25 wt% (hexane solution), 45 mL) and cyclohexane (Kanto Kagaku: 10 mL) Of the initiator solution prepared using (corresponding to the specific initiator described above), 60 mL was prepared with 1,3-butadiene (874 g, 16,133 mmol), styrene (manufactured by Kanto Chemical Co., Ltd .: 249 g, 2,390 mmol) and 4 A mixture of −tert-butyllithiumatechol (3.99 g, 24.0 mmol) was added to a solution of cyclohexane (4.24 kg) and stirred at 60 ° C. for 24 hours. After cooling to room temperature, a mixed solution of N-methylpyrrolidone (NMP) (5.00 g) in cyclohexane (10 mL) was added to terminate the polymerization. The resulting solution was removed and concentrated under reduced pressure. The concentrated solution was poured into methanol (5 L) to separate the methanol-insoluble component. As a result, a styrene-butadiene copolymer (NMP terminal-modified SBR) (953 g, Mn = 310,000, Mw = 810,000, PDI = 2.6) whose terminal was modified with N-methylpyrrolidone (NMP) was obtained. Obtained in a yield of 85%. It was estimated by IR analysis that vinyl / trans / cis = 6/40/54. The aromatic vinyl content (content of the repeating unit derived from styrene) was 25% by mass, and the glass transition temperature was −89 ° C.

<Specific copolymer 3 (unmodified SBR)>
n-BuLi (manufactured by Kanto Chemical Co., Ltd .: 1.60 mol / L (hexane solution), 18 mL, 28.8 mmol), bariumbis (2-ethylhexoxide) (Ba (OCH ₂ CH (C ₂ H ₅ ) CH ₂ CH) ₂ CH ₂ CH ₃ ) ₂ ) (STREM: 1M (toluene / hexane solution) 7.5 mL), trioctyl aluminum (Aldrich: 25 wt% (hexane solution), 45 mL) and cyclohexane (Kanto Kagaku: 10 mL) Of the initiator solution prepared using (corresponding to the specific initiator described above), 60 mL was prepared with 1,3-butadiene (874 g, 16,133 mmol), styrene (manufactured by Kanto Chemical Co., Ltd .: 249 g, 2,390 mmol) and 4 A mixture of −tert-butyllithiumatechol (3.99 g, 24.0 mmol) was added to a solution of cyclohexane (4.50 kg) and stirred at 60 ° C. for 14 hours. After cooling to room temperature, methanol (manufactured by Kanto Chemical Co., Inc .: 3.44 g) was added to terminate the polymerization. The resulting solution was removed and concentrated under reduced pressure. The concentrated solution was poured into methanol (10 L) to separate the methanol-insoluble component. As a result, a styrene-butadiene copolymer (unmodified SBR) (928 g, Mn = 170,000, Mw = 510,000, PDI = 3.0) was obtained in a yield of 83%. It was estimated by IR analysis that vinyl / trans / cis = 5/80/15. The aromatic vinyl content (content of the repeating unit derived from styrene) was 23% by mass, and the glass transition temperature was −78 ° C.

[Manufacturing of rubber compositions for conveyor belts]
The rubber compositions for conveyor belts of Examples and Comparative Examples were produced by mixing the components shown in Table 1 below at the ratio (parts by mass) shown in the same table. Specifically, first, among the components shown in Table 1 below, the components excluding sulfur and the vulcanization accelerator are mixed with a Banbury mixer for 5 minutes, and then sulfur and the vulcanization accelerator are added to the obtained mixture. , A rubber composition for a conveyor belt was produced by mixing using a roll.

[Preparation of vulcanized rubber sheet for evaluation]
The obtained rubber composition for a conveyor belt was formed into a sheet and vulcanized by heating at 148 ° C. for 30 minutes (40 minutes for a test piece for cut resistance) to prepare a vulcanized rubber sheet.

[Evaluation]
The obtained vulcanized rubber sheet was evaluated as follows.

<Cut resistance>
At room temperature, the blade (blade length 100 mm, tip angle 20 ° of the blade edge 2 mm, weight 8 kg) was naturally dropped onto the vulcanized rubber sheet from 25 cm above the obtained vulcanized rubber sheet, and the vulcanized rubber sheet was formed. The depth (mm) of the cracks formed was measured. The results are shown in Table 1. The results are represented by an index with Comparative Example 1 as 100. The smaller the index, the better the cut resistance.

<TB, EB>
The obtained vulcanized rubber sheet was subjected to a tensile test under the condition of a tensile speed of 500 mm / min according to JIS K6251: 2010, and the breaking strength (TB) and breaking elongation (EB) were measured at room temperature. The results are shown in Table 1. The results are represented by an index with Comparative Example 1 as 100. The larger the index, the better the gouging resistance.

Details of each component shown in Table 1 above are as follows.
・ NR: TSR20 (natural rubber)
SBR-1: NIPOL 1502 (SBR, aromatic vinyl content (content of repeating unit derived from styrene): 24.2% by mass, vinyl structure ratio: 15.7 mol%, Tg: -54 ° C.) , Mw: 4.9 × ^10-5 , manufactured by Zeon Corporation)
SBR-2: NIPOL NS612 (SBR, aromatic vinyl content (content of repeating unit derived from styrene): 15.1% by mass, vinyl structure ratio: 32.2 mol%, Tg: -61 ° C., Mw: 420,000, manufactured by Zeon Corporation)
SBR-3: NIPOL NS616 (SBR, aromatic vinyl content (content of repeating unit derived from styrene): 22.7% by mass, proportion of vinyl structure: 69.7 mol%, Tg: -22 ° C, Mw: 1,100,000, manufactured by Zeon Corporation)
SBR-4: Toughden 2000R (SBR, aromatic vinyl content (content of repeating unit derived from styrene): 25% by mass, vinyl / trans / cis = 9/55/36, Tg: -70 ° C, Mw : 260,000, manufactured by Asahi Kasei Corporation)
-Comparative specific copolymer: Comparative specific copolymer (unmodified SBR) synthesized as described above.
-Specific copolymer 1: Specific copolymer 1 (unmodified SBR) synthesized as described above.
-Specific copolymer 2: Specific copolymer 2 (NMP terminal-modified SBR) synthesized as described above.
-Specific copolymer 3: Specific copolymer 3 (unmodified SBR) synthesized as described above.
-CB (ISAF): Show Black N220 (ISAF grade carbon black, manufactured by Cabot Japan)
-Silica: Nip seal AQ (silica, manufactured by Toso Silica)
-Resin: High Resin # 120S (manufactured by Toho Chemical Industry Co., Ltd.)
-Anti-aging agent: Santoflex 6PPD (manufactured by Flexis)
・ Zinc oxide: 3 types of zinc oxide (manufactured by Shodo Chemical Industry Co., Ltd.)
-Stearic acid: Stearic acid (manufactured by NOF CORPORATION)
・ Oil: A-OMIX (manufactured by Sankyo Yuka Kogyo Co., Ltd.)
-Vulcanization accelerator: Noxeller NS-P (manufactured by Ouchi Shinko Kagaku Co., Ltd.)
・ Sulfur: Fine sulfur powder containing Jinhua stamp oil (manufactured by Tsurumi Chemical Industry Co., Ltd.)

As can be seen from Table 1, the examples of the present application containing the specific copolymer showed excellent cut resistance and gouging resistance. Among them, Examples 1 and 2 in which the ratio of the 1,4-cis structure to the repeating unit derived from the conjugated diene in which the specific copolymer is 17 mol% or more are more excellent cut resistance and gouging resistance. showed that.
From the comparison between Examples 1 and 2, Example 2 whose end was modified with a specific denaturant showed better cut resistance and gouging resistance.

On the other hand, Comparative Examples 1 to 5 which do not contain the specific copolymer and Comparative Example 6 which contains the specific copolymer but contains the specific copolymer in the diene rubber in an amount of 50% by mass or more are cut resistant. At least one of the properties and gouging resistance was insufficient.

1: Conveyor belt 2: Top cover rubber layer 3: Reinforcing layer 4: Bottom cover rubber layer 5: Transport surface 11, 16: Outer layer 12, 15: Inner layer

Claims (6)

As the rubber component, an aromatic vinyl - conjugated diene copolymer containing only 60 to 90 mass% including diene rubber unrealized natural rubber least 10 mass% 40 mass% or less,
The aromatic vinyl-conjugated diene copolymer has a content of repeating units derived from aromatic vinyl of more than 20% by mass, and the proportion of vinyl structure among the repeating units derived from conjugated diene is 8 mol% or less. There is a rubber composition for conveyor belts. The rubber composition for a conveyor belt according to claim 1, wherein the aromatic vinyl-conjugated diene copolymer has a glass transition temperature of −50 ° C. or lower. The rubber composition for a conveyor belt according to claim 1 or 2, wherein the aromatic vinyl-conjugated diene copolymer has a weight average molecular weight of 200,000 to 10,000,000. The one according to any one of claims 1 to 3, wherein the aromatic vinyl-conjugated diene copolymer has a ratio of 1,4-cis structure in 17 mol% or more of the repeating units derived from the conjugated diene. Rubber composition for conveyor belts. It has an upper surface cover rubber layer, a reinforcing layer, and a lower surface cover rubber layer.
A conveyor belt in which at least the upper surface cover rubber layer is formed by using the rubber composition for a conveyor belt according to any one of claims 1 to 4. A belt conveyor equipped with the conveyor belt according to claim 5.

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