JP2020094110A - Rubber composition for heavy duty tires, and heavy duty tire - Google Patents

Abstract

To provide a rubber composition for heavy duty tires which is excellent in balance of wear resistance of tires, fuel economy of tires, and workability, and to provide a heavy duty tire using the same.SOLUTION: The rubber composition for heavy duty tires contains: a rubber component containing a multi-component copolymer which contains a conjugated diene unit, a non-conjugated olefin unit, and an aromatic vinyl unit; and a filler containing carbon black. The content of the carbon black is 30 pts.mass or more and 60 pts.mass or less based on 100 pts.mass of the rubber component. The content of the carbon black in the filler is 52 mass% or more and 90 mass% or less.SELECTED DRAWING: None

Description

The present invention relates to a rubber composition for heavy duty tires and a heavy duty tire.

In general, heavy-duty tires are required to have high abrasion resistance, and in order to meet such requirements, a rubber material having high abrasion resistance is desired.
With respect to the above-mentioned problems, for example, styrene-butadiene copolymer rubbers 5 to 40 in which the amount of 1,4-cis bond in butadiene is 70% by weight or more and the amount of 1,2-vinyl bond is less than 10% by weight. A rubber composition for heavy-duty tires is known which is composed of 95 parts by weight of natural rubber and 95 to 60 parts by weight of natural rubber (see, for example, Patent Document 1).

JP, 2006-137893, A

However, with the method described in Patent Document 1, it was not possible to parallelize the wear resistance and fuel economy of tires and the workability of rubber compositions.

An object of the present invention is to provide a rubber composition for tires for heavy loads, which has an excellent balance of tire wear resistance, fuel efficiency, and workability, and a tire for heavy loads using the same, and to solve the object. Is an issue.

<1> A rubber component containing a multicomponent copolymer containing a conjugated diene unit, a non-conjugated olefin unit, and an aromatic vinyl unit, and a filler containing carbon black, wherein the content of the carbon black is the rubber. A rubber composition for heavy duty tires, which is 30 parts by mass or more and 60 parts by mass or less with respect to 100 parts by mass of the component, and the content of the carbon black in the filler is 52% by mass or more and 90% by mass or less.

<2> The rubber component further contains natural rubber, the content of the multicomponent copolymer in the rubber component is 5% by mass or more and 95% by mass or less, and the content of the natural rubber in the rubber component Is 5% by mass or more and 95% by mass or less, the rubber composition for heavy-duty tires according to <1>.
<3> The rubber composition for heavy duty tires according to <1> or <2>, wherein the filler further contains 5 parts by mass or more and 28 parts by mass or less of silica with respect to 100 parts by mass of the rubber component.

<4> In the multicomponent copolymer, the content of the conjugated diene unit is 1 to 50 mol%, the content of the non-conjugated olefin unit is 40 to 97 mol%, and the content of the aromatic vinyl unit is The rubber composition for heavy duty tires according to any one of <1> to <3>, which is 2 to 35 mol %.

<5> The multicomponent copolymer according to any one of <1> to <4>, which has an endothermic peak energy of 10 to 150 J/g measured by a differential scanning calorimeter (DSC) at 0 to 120°C. The heavy-duty tire rubber composition.
<6> The rubber composition for heavy-duty tires according to any one of <1> to <5>, wherein the multicomponent copolymer has a melting point of 30 to 130° C. measured by a differential scanning calorimeter (DSC). ..
<7> The rubber composition for heavy-duty tires according to any one of <1> to <6>, wherein the multicomponent copolymer has a glass transition temperature of 0° C. or lower measured by a differential scanning calorimeter (DSC). Stuff.

<8> The rubber composition for a heavy duty tire according to any one of <1> to <7>, wherein the multicomponent copolymer has a crystallinity of 0.5 to 50%.
<9> The rubber composition for heavy-duty tires according to any one of <1> to <8>, in which the multi-component copolymer has a main chain composed only of an acyclic structure.

<10> The rubber composition for heavy duty tires according to any one of <1> to <9>, in which the non-conjugated olefin unit is an acyclic non-conjugated olefin unit.
<11> The rubber composition for heavy duty tires according to <10>, wherein the non-cyclic non-conjugated olefin unit is composed of only ethylene units.
<12> The rubber composition for a heavy duty tire according to any one of <1> to <11>, in which the aromatic vinyl unit contains a styrene unit.
<13> The rubber composition for heavy duty tires according to any one of <1> to <12>, in which the conjugated diene unit contains at least one selected from the group consisting of a 1,3-butadiene unit and an isoprene unit. Stuff.

<14> A heavy duty tire using the rubber composition for a heavy duty tire according to any one of <1> to <13>.

ADVANTAGE OF THE INVENTION According to this invention, the rubber composition for tires for heavy loads which is excellent in the balance of abrasion resistance of a tire, fuel efficiency, and workability, and the tire for heavy loads using the same can be provided.

Hereinafter, the present invention will be described in detail based on its embodiments.
In addition, in the following description, the description of “A to B” indicating a numerical range represents a numerical range including A and B which are end points, and is “A or more and B or less” (when A<B) or “A. Hereinafter, “B or more” (when B<A) is represented.
Moreover, a mass part and mass% are synonymous with a weight part and weight%, respectively.

<Rubber composition for heavy duty tires>
The heavy-duty tire rubber composition of the present invention comprises a rubber component containing a conjugated diene unit, a non-conjugated olefin unit, and a multicomponent copolymer containing an aromatic vinyl unit, and a filler containing carbon black. The content of black is 30 parts by mass or more and 60 parts by mass or less with respect to 100 parts by mass of the rubber component, and the content of carbon black in the filler is 52 parts by mass or more and 90 parts by mass or less.
Hereinafter, the "rubber composition for heavy duty tires" may be simply referred to as "rubber composition".

Conventionally, it has been necessary to mix a large amount of carbon black as a filler in a rubber composition for a tire that is required to have durability and wear resistance, such as a heavy duty tire. Higher fuel efficiency, wear resistance, and workability of the rubber composition are required, but it has been difficult to improve the balance by the conventional method.
On the other hand, the rubber composition of the present invention, having the above-mentioned constitution, has workability of the rubber composition, wear resistance of the heavy duty tire obtained by vulcanizing the rubber composition, and low fuel consumption. Excellent balance of 3 characteristics. This is presumed to be due to the following reasons.

Since the multi-component copolymer contained in the present rubber composition contains a crystal component derived from a non-conjugated olefin, when the strain of the multi-component copolymer is low, the crystal behaves as a pseudo-crosslinking point and energy loss can be reduced. it can. On the other hand, when the strain of the multi-component copolymer is high, it is considered that the abrasion resistance is excellent due to the energy dissipation by the crystal melting. By obtaining a heavy-duty tire with a vulcanized rubber of a rubber composition containing such a multi-component polymer, the heavy-duty tire is considered to have excellent wear resistance and fuel economy. Further, by including a multi-component copolymer having excellent strength, it is possible to increase the strength of a heavy-duty tire without relying on the excessive blending of carbon black, so that the viscosity of the rubber composition does not become too large, and workability is improved. It is also considered excellent.
From the above, it is considered that the rubber composition of the present invention has an excellent balance between workability of the rubber composition, wear resistance of a heavy duty tire obtained by vulcanizing the rubber composition, and low fuel consumption.
Hereinafter, the rubber composition of the present invention will be described in detail.

[Rubber component]
The rubber composition of the present invention contains a rubber component containing a multicomponent copolymer containing a conjugated diene unit, a non-conjugated olefin unit, and an aromatic vinyl unit.
Since the rubber composition contains a multi-component copolymer as a rubber component, the vulcanized rubber is excellent in abrasion resistance and fuel economy, and also the workability of the rubber composition is excellent.

(Multi-component copolymer)
The multi-component copolymer contained in the rubber component (hereinafter sometimes referred to as the multi-component polymer of the present invention) contains a conjugated diene unit, a non-conjugated olefin unit, and an aromatic vinyl unit.
When the multi-component copolymer contains a non-conjugated olefin unit, the belt layer or the carcass is greatly distorted, and when the tire is largely distorted, the crystal component derived from the non-conjugated olefin unit is collapsed, and the multi-component co-polymer is caused by the melting energy. Coalescence can dissipate energy. As a result, the tire can realize excellent wear resistance, crack growth resistance, durability such as rigidity. On the other hand, when the tire strain is low, the crystals derived from the non-conjugated olefin unit behave as pseudo-crosslinking points, and energy loss can be reduced. As a result, the tire can realize low fuel consumption.

The multi-component copolymer of the present invention contains at least a conjugated diene unit, a non-conjugated olefin unit, and an aromatic vinyl unit, but is composed only of a conjugated diene unit, a non-conjugated olefin unit, and an aromatic vinyl unit. Or may further contain another monomer unit.

The conjugated diene unit is a constitutional unit derived from a conjugated diene compound as a monomer.
By including the conjugated diene unit, the multi-component copolymer can be vulcanized, and the tire exhibits elasticity and strength.
Here, the conjugated diene compound refers to a conjugated diene compound. The conjugated diene compound preferably has 4 to 8 carbon atoms. Specific examples of the conjugated diene compound include 1,3-butadiene, isoprene, 1,3-pentadiene, and 2,3-dimethyl-1,3-butadiene. The conjugated diene compound may be a single compound or a combination of two or more compounds.

The conjugated diene compound as a monomer of the multicomponent copolymer preferably contains at least one selected from the group consisting of 1,3-butadiene and isoprene from the viewpoint of effectively improving the durability of the tire. More preferably, it consists of at least one selected from the group consisting of 1,3-butadiene and isoprene, and even more preferably consists of only 1,3-butadiene.
In other words, the conjugated diene unit in the multicomponent copolymer preferably contains at least one selected from the group consisting of 1,3-butadiene unit and isoprene unit, and the 1,3-butadiene unit and isoprene unit are preferred. More preferably, it consists of at least one selected from the group consisting of, and even more preferably consists of only 1,3-butadiene units.

The content of the conjugated diene unit in the multicomponent copolymer is preferably 1 mol% or more, more preferably 3 mol% or more, and preferably 50 mol% or less, and 40 mol% or less. Is more preferable, 30 mol% or less is more preferable, 25 mol% or less is still more preferable, and 15 mol% or less is still more preferable. When the content of the conjugated diene unit is 1 mol% or more of the whole multi-component copolymer, a tire having excellent elongation can be obtained, and when it is 50 mol% or less, the tire has wear resistance and low fuel consumption. Excel.
Further, the content of the conjugated diene unit is preferably in the range of 1 to 50 mol% of the whole multicomponent copolymer, and more preferably in the range of 3 to 40 mol %.

The non-conjugated olefin unit is a constitutional unit derived from a non-conjugated olefin compound as a monomer.
When the tire is severely distorted, the crystalline components originating from the non-conjugated olefin units disintegrate, dissipating energy from the multipolymer.
Here, the non-conjugated olefin compound means a compound which is an aliphatic unsaturated hydrocarbon and has one or more carbon-carbon double bonds. The non-conjugated olefin compound preferably has 2 to 10 carbon atoms. Specific examples of the non-conjugated olefin compound include α-olefins such as ethylene, propylene, 1-butene, 1-pentene, 1-hexene, 1-heptene, and 1-octene, vinyl pivalate, and 1-phenylthioethene. And hetero atom-substituted alkene compounds such as N-vinylpyrrolidone. The non-conjugated olefin compound may be a single compound or a combination of two or more compounds.

The non-conjugated olefin compound as a monomer of the multi-component copolymer is preferably a non-cyclic non-conjugated olefin compound from the viewpoint of further improving wear resistance and fuel economy of the tire, and also non-cyclic. The non-conjugated olefin compound is more preferably an α-olefin, even more preferably an α-olefin containing ethylene, and particularly preferably only ethylene.
In other words, the non-conjugated olefin unit in the multi-component copolymer is preferably an acyclic non-conjugated olefin unit, and the acyclic non-conjugated olefin unit is an α-olefin unit. More preferably, it is more preferably an α-olefin unit containing an ethylene unit, and particularly preferably only an ethylene unit.

The content of the non-conjugated olefin unit in the multicomponent copolymer is preferably 40 mol% or more, more preferably 45 mol% or more, even more preferably 55 mol% or more, and 60 mol% or more. Particularly preferred is 97 mol% or less, more preferred is 95 mol% or less, and further preferred is 90 mol% or less.
When the content of the non-conjugated olefin unit is 40 mol% or more of the whole multi-component copolymer, the content of the conjugated diene unit or the aromatic vinyl unit decreases as a result, and the wear resistance and fuel economy of the tire are reduced. improves. Further, when the content of the non-conjugated olefin unit is 97 mol% or less, the content of the conjugated diene unit or the aromatic vinyl unit is increased as a result, and the durability of the tire at high temperature is improved. In addition, the content of the non-conjugated olefin unit is preferably in the range of 40 to 97 mol% of the whole multicomponent copolymer, more preferably in the range of 45 to 95 mol%, still more preferably in the range of 55 to 90 mol%.

The aromatic vinyl unit is a constitutional unit derived from an aromatic vinyl compound as a monomer.
Since the multi-component polymer contains an aromatic vinyl unit, excessive crystallization derived from the non-conjugated olefin unit is suppressed, and while improving the rigidity of the multi-component copolymer, it is difficult to impair the elasticity of the vulcanized rubber obtained. ..
Here, the aromatic vinyl compound refers to an aromatic compound substituted with at least a vinyl group, and is not included in the conjugated diene compound. The aromatic vinyl compound preferably has 8 to 10 carbon atoms. Examples of the aromatic vinyl compound include styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, o,p-dimethylstyrene, o-ethylstyrene, m-ethylstyrene and p-ethylstyrene. .. The aromatic vinyl compound may be a single compound or a combination of two or more compounds.

The aromatic vinyl compound as a monomer of the multi-component copolymer preferably contains styrene, more preferably only styrene, from the viewpoint of improving wear resistance and fuel economy of the tire. In other words, the aromatic vinyl unit in the multicomponent copolymer preferably contains a styrene unit, and more preferably consists of only a styrene unit.
The aromatic ring in the aromatic vinyl unit is not included in the main chain of the multi-component copolymer unless it is bonded to the adjacent unit.

The content of the aromatic vinyl unit in the multi-component copolymer is preferably 2 mol% or more, more preferably 3 mol% or more, and further preferably 35 mol% or less, and 30 mol% or less. It is more preferable that the amount is 25 mol% or less, and even more preferable that the amount is 25 mol% or less. When the content of the aromatic vinyl unit is 2 mol% or more, the wear resistance and fuel economy of the tire at high temperatures are improved. When the content of the aromatic vinyl unit is 35 mol% or less, the effect of the conjugated diene unit and the non-conjugated olefin unit becomes remarkable. The content of aromatic vinyl units is preferably in the range of 2 to 35 mol%, more preferably 3 to 30 mol%, and even more preferably 3 to 25 mol% of the whole multicomponent copolymer.

The number of types of monomers of the multicomponent copolymer is not particularly limited as long as the multicomponent copolymer contains a conjugated diene unit, a non-conjugated olefin unit, and an aromatic vinyl unit. The multi-component copolymer may have other constitutional units other than the conjugated diene unit, the non-conjugated olefin unit, and the aromatic vinyl unit, but the content of the other constitutional unit obtains a desired effect. From the viewpoint, it is preferably 30 mol% or less, more preferably 20 mol% or less, and further preferably 10 mol% or less of the whole multicomponent copolymer, that is, not contained, that is, the content is 0 mol%. It is particularly preferable that

From the viewpoint of making the wear resistance and fuel economy of the tire and the crystallinity of the multicomponent copolymer preferable, the multicomponent copolymer, as a monomer, only one conjugated diene compound, only one non-conjugated olefin. A polymer obtained by polymerizing at least a compound and one kind of aromatic vinyl compound is preferable.
In other words, the multicomponent copolymer is preferably a multicomponent copolymer containing only one conjugated diene unit, only one non-conjugated olefin unit, and only one aromatic vinyl unit, and only one component. Is more preferably a terpolymer consisting only of conjugated diene units, only one non-conjugated olefin unit, and only one aromatic vinyl unit, and only 1,3-butadiene unit, ethylene unit, and styrene unit. It is more preferable that the terpolymer is composed of Here, "only one kind of conjugated diene unit" includes conjugated diene units having different bonding modes.

In the rubber composition of the present invention, the multicomponent copolymer has a conjugated diene unit content of 1 to 50 mol%, a non-conjugated olefin unit content of 40 to 97 mol%, and an aromatic vinyl unit content. The amount is preferably 2-35 mol %. In this case, the wear resistance and fuel economy of the tire are further improved.

The polystyrene-equivalent weight average molecular weight (Mw) of the multi-component copolymer is preferably 10,000 to 10,000,000, more preferably 100,000 to 9,000,000, and more preferably 150,000. More preferably, it is about 8,000,000. When the Mw of the multi-component copolymer is 10,000 or more, the mechanical strength of the tire can be sufficiently secured, and when the Mw is 10,000,000 or less, the rubber composition of the present invention can be obtained. Hard to impair the workability of objects.

The polystyrene-equivalent number average molecular weight (Mn) of the multicomponent copolymer is preferably 10,000 to 10,000,000, more preferably 50,000 to 9,000,000, and more preferably 100,000. More preferably, it is about 8,000,000. When the Mn of the multi-component copolymer is 10,000 or more, the mechanical strength of the tire can be sufficiently secured, and when the Mn is 10,000,000 or less, the rubber composition of the present invention can be obtained. Hard to impair the workability of objects.

The multi-component copolymer has a molecular weight distribution [Mw/Mn (weight average molecular weight/number average molecular weight)] of preferably 1.00 to 4.00, more preferably 1.50 to 3.50, More preferably, it is 1.80 to 3.00. When the molecular weight distribution of the multicomponent copolymer is 4.00 or less, sufficient homogeneity can be brought about in the physical properties of the multicomponent copolymer.

The weight average molecular weight (Mw), number average molecular weight (Mn) and molecular weight distribution (Mw/Mn) of the multicomponent copolymer are determined by gel permeation chromatography (GPC) using polystyrene as a standard substance.

The endothermic peak energy of the multicomponent copolymer measured by a differential scanning calorimeter (DSC) at 0 to 120° C. is preferably 10 to 150 J/g, more preferably 30 to 120 J/g. When the endothermic peak energy of the multicomponent copolymer is 10 J/g or more, the crystallinity of the multicomponent copolymer is increased, and the wear resistance and fuel economy of the tire can be further improved. When the endothermic peak energy of the multicomponent copolymer is 150 J/g or less, the workability of the rubber composition of the present invention is improved.
Here, the endothermic peak energy is a value measured by the method described in Examples.

The multicomponent copolymer preferably has a melting point measured by a differential scanning calorimeter (DSC) of 30 to 130°C, more preferably 30 to 110°C, and more preferably 30 to 90°C. When the melting point of the multicomponent copolymer is 30° C. or higher, the crystallinity of the multicomponent copolymer becomes high, and the wear resistance and fuel economy of the tire can be further improved. Further, when the melting point of the multicomponent copolymer is 130° C. or lower, the workability of the rubber composition of the present invention is improved.
Here, the melting point is a value measured by the method described in the examples.

The glass transition temperature (Tg) of the multicomponent copolymer measured by a differential scanning calorimeter (DSC) is preferably 0°C or lower, more preferably -100 to -10°C. When the glass transition temperature of the multi-component copolymer is 0°C or lower, the workability of the rubber composition of the present invention is improved.
Here, the glass transition temperature is a value measured by the method described in Examples.

The crystallinity of the multicomponent copolymer is preferably 0.5 to 50%, more preferably 3 to 45%, and further preferably 5 to 45%. When the crystallinity of the multicomponent copolymer is 0.5% or more, the crystallinity of the multicomponent copolymer due to the non-conjugated olefin unit is sufficiently secured to further improve the wear resistance and fuel economy of the tire. Can be improved. Further, when the crystallinity of the multi-component copolymer is 50% or less, workability during kneading of the rubber composition of the present invention is improved, and the tackiness of the rubber composition of the present invention is increased. Therefore, the workability at the time of sticking the rubber members made of the rubber composition of the present invention to each other to form a rubber article such as a tire is also improved.
Here, the crystallinity is a value measured by the method described in Examples.

It is preferable that the main chain of the multicomponent copolymer is composed only of an acyclic structure. This can further improve the wear resistance and fuel economy of the tire.
In addition, NMR is used as a main measuring means for confirming whether or not the main chain of the multicomponent copolymer has a cyclic structure. Specifically, when the peak derived from the cyclic structure present in the main chain (for example, for 3 to 5 membered rings, the peak appearing at 10 to 24 ppm) is not observed, the main chain of the multicomponent copolymer is , Shows that it is composed of only an acyclic structure.

The multi-component copolymer can be produced through a polymerization step using a conjugated diene compound, a non-conjugated olefin compound, and an aromatic vinyl compound as monomers, and further, if necessary, a coupling step, a washing step, and other You may go through the process of.
Here, in the production of the multicomponent copolymer, it is preferable to add only the non-conjugated olefin compound and the aromatic vinyl compound in the presence of the polymerization catalyst without adding the conjugated diene compound, and polymerize them first. In particular, when the catalyst composition described below is used, the conjugated diene compound is higher in reactivity than the non-conjugated olefin compound and the aromatic vinyl compound, and therefore, the non-conjugated olefin compound and the aromatic compound are present in the presence of the conjugated diene compound. It is difficult to polymerize one or both of the group vinyl compounds. In addition, it is also difficult to polymerize the conjugated diene compound first and then additionally polymerize the non-conjugated olefin compound and the aromatic vinyl compound in terms of the characteristics of the catalyst.

As the polymerization method, any method such as a solution polymerization method, a suspension polymerization method, a liquid phase bulk polymerization method, an emulsion polymerization method, a gas phase polymerization method or a solid phase polymerization method can be used. When a solvent is used in the polymerization reaction, such a solvent may be one that is inactive in the polymerization reaction, and examples thereof include toluene, cyclohexane, and normal hexane.

The polymerization process may be performed in one stage or in multiple stages of two or more stages.
The one-step polymerization process means all kinds of monomers to be polymerized, that is, a conjugated diene compound, a non-conjugated olefin compound, an aromatic vinyl compound, and other monomers, preferably a conjugated diene compound, a non-conjugated compound. In this step, the olefin compound and the aromatic vinyl compound are simultaneously reacted and polymerized.
In addition, the multi-step polymerization process means that a part or all of one or two kinds of monomers are first reacted to form a polymer (first polymerization step), and then added in the first polymerization step. It is a step of polymerizing by carrying out one or more steps (second polymerization step to final polymerization step) of adding a monomer of a kind not performed, the rest of the monomer added in the first polymerization step, and the like to perform polymerization. .. In particular, in the production of multi-component copolymer, it is preferable to carry out the polymerization process in multiple stages.

In the polymerization step, the polymerization reaction is preferably carried out under an atmosphere of an inert gas, preferably nitrogen gas or argon gas. The polymerization temperature of the polymerization reaction is not particularly limited, but is preferably in the range of −100° C. to 200° C., and may be about room temperature. The pressure of the polymerization reaction is preferably in the range of 0.1 to 10.0 MPa so that the conjugated diene compound can be sufficiently incorporated into the polymerization reaction system.
Further, the reaction time of the polymerization reaction is not particularly limited, and for example, the range of 1 second to 10 days is preferable, but it can be appropriately selected depending on the conditions such as the type of polymerization catalyst and the polymerization temperature.
Further, in the step of polymerizing the conjugated diene compound, the polymerization may be stopped by using a polymerization terminator such as methanol, ethanol or isopropanol.

The polymerization process is preferably performed in multiple stages. More preferably, a first step of obtaining a polymerization mixture by mixing a first monomer raw material containing at least an aromatic vinyl compound and a polymerization catalyst, and a conjugated diene compound, a non-conjugated olefin compound, and It is preferable to carry out the second step of introducing a second monomer raw material containing at least one selected from the group consisting of aromatic vinyl compounds. Further, it is more preferable that the first monomer raw material does not include the conjugated diene compound and the second monomer raw material does not include the conjugated diene compound.

The first monomer raw material used in the first step may contain a non-conjugated olefin compound together with the aromatic vinyl compound. Further, the first monomer raw material may contain the whole amount of the aromatic vinyl compound used, or may contain only a part thereof. The non-conjugated olefin compound is contained in at least one of the first monomer raw material and the second monomer raw material.

The first step is preferably performed in a reactor under an atmosphere of an inert gas, preferably nitrogen gas or argon gas. The temperature (reaction temperature) in the first step is not particularly limited, but is preferably in the range of −100° C. to 200° C., and may be about room temperature. The pressure in the first step is not particularly limited, but is preferably in the range of 0.1 to 10.0 MPa in order to sufficiently incorporate the aromatic vinyl compound into the polymerization reaction system. The time spent in the first step (reaction time) can be appropriately selected depending on the conditions such as the type of polymerization catalyst and the reaction temperature. For example, when the reaction temperature is 25 to 80° C., 5 minutes is required. The range of up to 500 minutes is preferred.

In the first step, as a polymerization method for obtaining a polymerization mixture, any method such as a solution polymerization method, a suspension polymerization method, a liquid phase bulk polymerization method, an emulsion polymerization method, a gas phase polymerization method or a solid phase polymerization method may be used. Can be used. Further, when a solvent is used in the polymerization reaction, such a solvent may be one that is inactive in the polymerization reaction, and examples thereof include toluene, cyclohexanone, and normal hexane.

The second monomer raw material used in the second step is a conjugated diene compound alone, or a conjugated diene compound and a non-conjugated olefin compound, or a conjugated diene compound and an aromatic vinyl compound, or a conjugated diene compound and a non-conjugated olefin compound. And an aromatic vinyl compound are preferable.
In addition, when the second monomer raw material contains at least one selected from the group consisting of a non-conjugated olefin compound and an aromatic vinyl compound in addition to the conjugated diene compound, these monomer raw materials are previously used as a solvent or the like. It may be introduced into the polymerization mixture after being mixed together, or each monomer raw material may be introduced from a single state. Further, each monomer raw material may be added simultaneously or sequentially.
In the second step, the method of introducing the second monomer raw material into the polymerization mixture is not particularly limited, but the flow rate of each monomer raw material is controlled and continuously added to the polymerization mixture. It is preferable to do so-called metering. Here, when a monomer raw material that is a gas under the conditions of the polymerization reaction system (for example, ethylene as a non-conjugated olefin compound under conditions of room temperature and atmospheric pressure) is used, the polymerization reaction system is kept at a predetermined pressure. Can be introduced to.

The second step is preferably performed in a reactor under an atmosphere of an inert gas, preferably nitrogen gas or argon gas. The temperature (reaction temperature) in the second step is not particularly limited, but is preferably in the range of −100° C. to 200° C., and may be about room temperature. In addition, when the reaction temperature is increased, the selectivity of cis-1,4 bond in the conjugated diene unit may be decreased. The pressure in the second step is not particularly limited, but is preferably in the range of 0.1 to 10.0 MPa in order to sufficiently incorporate the monomer such as the conjugated diene compound into the polymerization reaction system. The time (reaction time) spent in the second step can be appropriately selected depending on the conditions such as the type of polymerization catalyst and the reaction temperature, but is preferably 0.1 hour to 10 days.
In the second step, the polymerization reaction may be stopped by using a polymerization terminator such as methanol, ethanol or isopropanol.

Here, in the step of polymerizing the conjugated diene compound, the non-conjugated olefin compound, and the aromatic vinyl compound, various monomers are added in the presence of at least one of the following components (A) to (F) as a catalyst component. It preferably includes a step of polymerizing. In the polymerization step, it is preferable to use one or more of the following components (A) to (F), but it is possible to use two or more of the following components (A) to (F) in combination as a catalyst composition. More preferable.
Component (A): rare earth element compound or a reaction product of the rare earth element compound with a Lewis base (B) component: organometallic compound (C) component: aluminoxane (D) component: ionic compound (E) component: halogen compound ( Component F): substituted or unsubstituted cyclopentadiene (compound having cyclopentadienyl group), substituted or unsubstituted indene (compound having indenyl group), and substituted or unsubstituted fluorene (compound having fluorenyl group) Cyclopentadiene skeleton-containing compound selected from the above) The components (A) to (F) can be used in the polymerization step by referring to, for example, International Publication No. 2018/092733.

The coupling step is a step of performing a reaction (coupling reaction) for modifying at least a part (for example, an end) of the polymer chain of the multicomponent copolymer obtained in the polymerization step.
In the coupling step, it is preferable to perform the coupling reaction when the polymerization reaction reaches 100%.
The coupling agent used in the coupling reaction is not particularly limited and may be appropriately selected depending on the intended purpose. Examples thereof include tin-containing compounds such as bis(-1-octadecyl maleate 1-octadecyl)dioctyltin (IV); 4 , 4'-diphenylmethanediisocyanate and other isocyanate compounds; glycidylpropyltrimethoxysilane and other alkoxysilane compounds. These may be used alone or in combination of two or more.
Among these, bis(1-octadecyl maleate-1-octadecyl)dioctyltin (IV) is preferable in terms of reaction efficiency and low gel formation.
The number average molecular weight (Mn) of the multi-component polymer can be increased by performing the coupling reaction.

The washing step is a step of washing the multicomponent copolymer obtained in the polymerization step.
The medium used for washing is not particularly limited and may be appropriately selected depending on the intended purpose. Examples thereof include methanol, ethanol and isopropanol. When a Lewis acid-derived catalyst is used as a polymerization catalyst, Can be used by adding an acid (for example, hydrochloric acid, sulfuric acid, nitric acid, etc.) to these solvents. The amount of acid added is preferably 15 mol% or less based on the solvent. When the added amount is 15 mol% or less, the acid is less likely to remain in the multicomponent copolymer, and the reaction during kneading and vulcanization of the rubber composition of the present invention is less likely to be adversely affected.
By this washing step, the amount of catalyst residue in the multi-component copolymer can be suitably reduced.

(Diene rubber)
The rubber component preferably further contains a diene rubber in addition to the multicomponent copolymer of the present invention.
The multi-component copolymer of the present invention contains a conjugated diene unit, but in the present invention, the multi-component copolymer of the present invention is not included in the diene rubber.
Examples of the diene rubber include natural rubber (NR) and synthetic diene rubber.
Specific examples of the synthetic diene rubber include polyisoprene rubber (IR), polybutadiene rubber (BR), styrene-butadiene copolymer rubber (SBR), chloroprene rubber (CR), halogenated butyl rubber, and acrylonitrile-butadiene. Examples thereof include rubber (NBR).
The diene rubber may be used alone or in combination of two or more.
Among the above, the diene rubber is preferably natural rubber, polyisoprene rubber, and polybutadiene rubber, and more preferably natural rubber.

The rubber component may include a non-diene rubber. As the non-diene rubber, for example, ethylene propylene rubber (EPDM (also referred to as EPM)), maleic acid-modified ethylene propylene rubber (M-EPM), butyl rubber (IIR), isobutylene and an aromatic vinyl or diene monomer Examples include polymers, acrylic rubber (ACM), ionomers and the like.

From the viewpoint of improving the wear resistance and fuel economy of the tire and improving the workability of the rubber composition, the content of the multicomponent copolymer in the rubber component is 5% by mass or more and 95% by mass or less. Preferably. When the content of the multi-component copolymer in the rubber component is 5% by mass or more, the rigidity of the vulcanized rubber can be improved and the energy loss can be further reduced. Therefore, the wear resistance and fuel economy of the tire can be improved. Can be further improved. Further, when the content of the multi-component copolymer in the rubber component is 95% by mass or less, the workability of the rubber composition is unlikely to be impaired.
From the viewpoint of further improving the wear resistance and fuel economy of the tire, the content of the multicomponent copolymer in the rubber component is preferably 10% by mass or more, and more preferably 20% by mass or more. From the viewpoint of workability of the rubber composition, the content of the multicomponent copolymer in the rubber component is preferably 80% by mass or less, more preferably 60% by mass or less, and less than 50% by mass. Is more preferable.

Further, from the viewpoint of improving the wear resistance and fuel economy of the tire and improving the workability of the rubber composition, the content of the diene rubber in the rubber component is 5% by mass or more and 95% by mass or less. Preferably. When the content of the diene rubber in the rubber component is 5% by mass or more, the rigidity of the vulcanized rubber can be improved and the energy loss can be further reduced, so that the wear resistance and fuel economy of the tire can be improved. It can be improved. Further, when the content of the diene rubber in the rubber component is 95% by mass or less, the workability of the rubber composition is less likely to be impaired.
From the viewpoint of further improving the wear resistance and fuel economy of the tire, the content of the diene rubber in the rubber component is preferably 30% by mass or more, more preferably 40% by mass or more, and 50 It is more preferable that the content is more than mass %. From the viewpoint of workability of the rubber composition, the content of the diene rubber in the rubber component is preferably 90% by mass or less, more preferably 80% by mass or less.

The rubber component includes a multicomponent copolymer and natural rubber, the content of the multicomponent copolymer in the rubber component is 5% by mass or more and 95% by mass or less, and the content of the natural rubber in the rubber component is 5% by mass. % Or more and 95% by mass or less is preferable. In addition, the total content of the multi-component copolymer and the content of the natural rubber in the rubber component is preferably 100% by mass.

〔filler〕
The rubber composition of the present invention contains a filler containing carbon black. The content of carbon black in the rubber composition is 30 parts by mass or more and 60 parts by mass or less with respect to 100 parts by mass of the rubber component, and the content of carbon black in the filler is 52% by mass or more and 90% by mass. It is below.
If the content of carbon black in the rubber composition is less than 30 parts by mass with respect to 100 parts by mass of the rubber component, abrasion resistance cannot be secured. If the content of carbon black in the rubber composition exceeds 60 parts by mass with respect to 100 parts by mass of the rubber component, fuel economy cannot be secured.
Further, if the content of carbon black in the filler is less than 52% by mass, abrasion resistance cannot be secured. If the content of carbon black in the filler exceeds 90% by mass, fuel economy cannot be secured.

From the viewpoint of abrasion resistance, the content of carbon black in the rubber composition is preferably 30 parts by mass or more, and more preferably 35 parts by mass or more, relative to 100 parts by mass of the rubber component. From the viewpoint of low fuel consumption, the content of carbon black in the rubber composition is preferably 45 parts by mass or less, and more preferably 40 parts by mass or less with respect to 100 parts by mass of the rubber component.
The content of carbon black in the filler is preferably 55% by mass or more, and more preferably 60% by mass or more, from the viewpoint of low fuel consumption. From the viewpoint of wear resistance, the content of carbon black in the filler is preferably 85% by mass or less, more preferably 80% by mass or less.

The carbon black is not particularly limited and can be appropriately selected according to the purpose. The carbon black is, for example, preferably FEF, SRF, HAF, ISAF or SAF grade, more preferably HAF, ISAF or SAF grade, further preferably HAF grade.
Further, from the viewpoint of further reducing energy loss, the carbon black is preferably a low structure carbon black in which the degree of development of the aggregate structure is low. Specifically, the oil absorption of dibutyl phthalate (DBP) is preferably 90 cm ³ /100 g or less, more preferably 85 cm ³ /100 g or less, and further preferably 80 cm ³ /100 g or less. From the viewpoint of the reinforcing property of the vulcanized rubber, the DBP oil absorption of carbon black may be 40 cm ³ /100 g or more.
The DBP oil absorption is measured by the method described in JIS K 6217-4:2001 "Determination of DBP Absorption", and is expressed as a volume ml of dibutyl phthalate (DBP) absorbed per 100 g of carbon black. ..

From the viewpoint of tire durability, carbon black preferably has a nitrogen adsorption specific surface area of 40 m ² /g or more. Also, when it is 95 m ² /g or less, the dispersibility of carbon black in the rubber composition is excellent, and the wear resistance of the tire is excellent.
From the same viewpoint, more preferably carbon black nitrogen adsorption specific surface area _(N 2 SA) is 50~95m ² / g, more preferably from 60~95m ² / g.
The nitrogen adsorption specific surface area (N ₂ SA) is measured based on JIS K 6217-2:2001.

The filler further contains a filler other than carbon black in a content of 10% by mass or more and 48% by mass or less in the filler.
Examples of the filler include metal oxides such as silica, zirconia, alumina and titania, and aluminum hydroxide. Above all, silica is preferably used from the viewpoint of excellent tire reinforcing properties and low fuel consumption.

(silica)
The silica is not particularly limited, and examples thereof include wet silica (hydrous silicic acid), dry silica (anhydrous silicic acid), and colloidal silica.
The content of silica is preferably 5 parts by mass or more and 28 parts by mass or less with respect to 100 parts by mass of the rubber component. When the content of silica in the rubber composition is 5 parts by mass or more with respect to 100 parts by mass of the rubber component, the wear resistance of the tire is excellent, and when it is 28 parts by mass or less, the fuel economy and the rubber of the tire are reduced. The workability of the composition is excellent.
The content of silica is more preferably 7 parts by mass or more, further preferably 10 parts by mass or more, and more preferably 25 parts by mass or less, and 20 parts by mass with respect to 100 parts by mass of the rubber component. It is more preferable that the amount is not more than mass parts.

Silica preferably has an adsorption specific surface area (CTAB adsorption specific surface area) measured by the cetyltrimethylammonium bromide adsorption method (CTAB) of 50 to 350 m ² /g, from the viewpoint of tire wear resistance and fuel economy. , 100 to 300 m ² /g is more preferable.
The CTAB adsorption specific surface area can be measured by a method based on the method of ASTM-D3765-80.
The silica having a CTAB adsorption specific surface area of 50 to 350 m ² /g may be a commercially available product, for example, NIPSIL AQ (trade name) of Tosoh Silica Co., Ltd., Zeosil 1115MP (trade name) of Rhodia, and Evonik Degussa. It is available as VN-3 (trade name).

[Silane coupling agent]
In order to further enhance the reinforcing property by strengthening the bond between the silica-rubber component and improving the dispersibility of silica, it is desirable that the rubber composition of the present invention further use a silane coupling agent.
The content of the silane coupling agent in the rubber composition is preferably 5 to 15% by mass or less based on the content of silica. When the content of the silane coupling agent is 15% by mass or less with respect to the content of silica, the effect of improving the reinforcing property and dispersibility of the vulcanized rubber can be obtained, and the economical efficiency is not easily deteriorated. Further, when the content of the silane coupling agent is 5% by mass or more with respect to the content of silica, the dispersibility of silica in the rubber composition can be enhanced.

The silane coupling agent is not particularly limited and is bis(3-triethoxysilylpropyl) disulfide, bis(3-triethoxysilylpropyl) trisulfide, bis(3-triethoxysilylpropyl) tetrasulfide, bis. (3-trimethoxysilylpropyl) disulfide, bis(3-trimethoxysilylpropyl) trisulfide, bis(3-trimethoxysilylpropyl) tetrasulfide, bis(2-triethoxysilylethyl) disulfide, bis(2-tri Ethoxysilylethyl) trisulfide, bis(2-triethoxysilylethyl) tetrasulfide, 3-trimethoxysilylpropylbenzothiazole disulfide, 3-trimethoxysilylpropylbenzothiazole trisulfide, 3-trimethoxysilylpropylbenzothiazole tetrasulfide And the like are preferred.

〔sulfur〕
The rubber composition of the present invention preferably contains sulfur.
The content of the vulcanizing agent in the rubber composition is usually 4 to 12 parts by mass and preferably 5 to 10 parts by mass with respect to 100 parts by mass of the rubber component.

The rubber composition of the present invention, together with the above components, if necessary, a compounding agent usually used in the rubber industry, for example, a softening agent, stearic acid, zinc white, a vulcanization accelerator, an antioxidant and the like, It may be appropriately selected and contained within a range not impairing the object of the present invention.

The rubber composition of the present invention is a multi-component copolymer, a diene rubber, a filler, each component such as sulfur is blended, by kneading using a kneader such as a Banbury mixer, a roll, an internal mixer, It can be manufactured. It is preferable that the respective components to be blended in the production of the rubber composition of the present invention are blended in the amounts shown as the contents of the respective components in the rubber composition of the present invention.
The kneading of each component may be carried out in one step or in two or more steps.

<Tires for heavy loads>
The heavy duty tire of the present invention is a vulcanized rubber obtained by vulcanizing the heavy duty tire rubber composition of the present invention, and is excellent in wear resistance and fuel economy. The heavy-duty tire of the present invention is preferably a heavy-duty tire using the rubber composition for heavy-duty tires of the present invention as a tread.
After the rubber composition of the present invention is molded and processed, it is vulcanized to produce a tire tread. The tire tread is preferably used as a tread ground contact portion.
Further, a tire is manufactured by using the rubber composition of the present invention in a tread by a usual tire manufacturing method. That is, the rubber composition for a tire of the present invention containing various components as described above is processed into a tire tread at an unvulcanized stage, and is pasted and molded by a usual method on a tire molding machine to obtain a raw tire. Molded. The raw tire is heated and pressed in a vulcanizer to obtain a tire.

Hereinafter, the present invention will be described in more detail with reference to examples, but these examples are intended to illustrate the present invention and do not limit the present invention in any way.

<Preparation of rubber composition and preparation of tire>
Each component was blended according to the formulation of Table 1 and kneaded to obtain a rubber composition. The obtained rubber composition was applied to a tread rubber, and a heavy-duty tire of size: 11R22.5 was prototyped according to a conventional method.
Details of the components in Table 1 are as follows.

(1) Rubber component/natural rubber: TSR20
-Multi-component copolymer: Ternary copolymer produced by the following production method-Styrene-butadiene rubber: Styrene-butadiene copolymer rubber, manufactured by JSR Corporation, trade name "SBR #1500"

(2) Filler/Carbon Black (CB): Asahi Carbon Co., Ltd., trade name “#70L” (DBP oil absorption=75 cm ³ /100 g; nitrogen adsorption specific surface area (N ₂ SA)=77 m ² /g)
・Silica: Tosoh Silica Co., Ltd., trade name “Nipseal AQ” (CTAB adsorption specific surface area: 150 m ² /g)

(3) Silane coupling agent: manufactured by Shin-Etsu Chemical Co., Ltd., trade name "ABC-856"
(4) Stearic acid: Shin-Nippon Rika Co., Ltd., trade name "Stearic acid 50S"
(5) Zinc oxide: manufactured by Huxui Tech Co., Ltd., product name "No. 3 Zinc Flower"
(6) Antiaging agent: N-phenyl-N'-(1,3-dimethylbutyl)-p-phenylenediamine, manufactured by Ouchi Shinko Chemical Industry Co., Ltd., trade name "Nocrac 6C"
(7) Oil: A/O MIX manufactured by JX Nippon Oil & Energy Corporation
(8) Wax: manufactured by Nippon Seiro Co., Ltd., product name "Ozoace-0701"
(9) Vulcanization accelerator: Ouchi Shinko Chemical Industry Co., Ltd., trade name "NOXCELLER CZ"
(10) Vulcanizing agent: Sulfur, manufactured by Tsurumi Chemical Industry Co., Ltd., trade name "powdered sulfur"

[Method for producing terpolymer]
160 g of styrene and 600 mL of toluene were added to a sufficiently dried pressure resistant stainless steel reactor of 1000 mL.
Mono(bis(1,3-tert-butyldimethylsilyl)indenyl)bis(bis(dimethylsilyl)amide gadolinium complex {1,3-[(t-Bu) in a glass container in a nitrogen atmosphere glove box. _{Me 2 Si] 2 C 9 H} 5 Gd [N (SiHMe 2) 2] 2} 0.25mmol, dimethylanilinium tetrakis (pentafluorophenyl) borate _{[Me 2 NHPhB (C 6 F} 5) 4] 0.275mmol, And 1.1 mmol of diisobutylaluminum hydride were charged and dissolved in 40 mL of toluene to obtain a catalyst solution.

The catalyst solution was added to the pressure-resistant stainless steel reactor and heated to 70°C.
Next, ethylene was charged into the pressure-resistant stainless steel reactor at a pressure of 1.5 MPa, and 80 mL of a toluene solution containing 20 g of 1,3-butadiene was further charged into the pressure-resistant stainless steel reactor over 8 hours, and a total of 8 at 70°C. Copolymerization was carried out for 5 hours.
Next, 1 ml of an isopropanol solution containing 5% by mass of 2,2′-methylene-bis(4-ethyl-6-t-butylphenol) (NS-5) was added to the pressure-resistant stainless steel reactor to stop the reaction.
Then, the copolymer was separated using a large amount of methanol and dried in vacuum at 50° C. to obtain a terpolymer.

The obtained terpolymer had a number average molecular weight (Mn) of 163,000, a weight average molecular weight (Mw) of 399,000, and a molecular weight distribution (Mw/Mn) of 2.4. .. The terpolymer had a butadiene unit content of 8 mol%, an ethylene unit content of 85 mol%, and a styrene unit content of 7 mol%. Furthermore, the ternary copolymer had a melting point (T _m ) of 63° C., an endothermic peak energy of 43.1 J/g, a glass transition temperature (Tg) of −28° C., and a crystallinity of 14.7%. ..
In the ¹³ C-NMR spectrum chart of the terpolymer, no peak was observed at 10 to 24 ppm, which confirmed that the synthesized terpolymer had a main chain consisting only of an acyclic structure.
These physical properties were measured by the following methods.

[Method of measuring physical properties of terpolymer]
(1) Number average molecular weight (Mn), weight average molecular weight (Mw) and molecular weight distribution (Mw/Mn)
Monodisperse polystyrene was analyzed by gel permeation chromatography [GPC: Tosoh HLC-8121GPC/HT, column: Tosoh GMH _HR- H(S)HT x 2, detector: differential refractometer (RI)]. As a standard, the polystyrene-equivalent number average molecular weight (Mn), weight average molecular weight (Mw), and molecular weight distribution (Mw/Mn) of the copolymer were determined. The measurement temperature is 40°C.

(2) Content of butadiene unit, ethylene unit, and styrene unit The content (mol%) of butadiene unit, ethylene unit, and styrene unit in the copolymer was measured by ¹ H-NMR spectrum (100° C., d-tetrachloroethane standard). : 6 ppm).

(3) Melting point ( _Tm )
The melting point of the copolymer was measured using a differential scanning calorimeter (DSC, manufactured by TA Instruments Japan, "DSCQ2000") in accordance with JIS K 7121-1987.

(4) Endothermic peak energy Using a differential scanning calorimeter (DSC, manufactured by TA Instruments Japan Co., Ltd., "DSCQ2000"), in accordance with JIS K 7121-1987, a heating rate of 10°C/min. Then, the temperature was raised from -150°C to 150°C, and the endothermic peak energy at 0 to 120°C at that time (1st run) was measured.

(5) Glass transition temperature (Tg)
The glass transition temperature (Tg) of the copolymer was measured using a differential scanning calorimeter (DSC, manufactured by TA Instruments Japan Co., Ltd., "DSCQ2000") in accordance with JIS K 7121-1987.

(6) Crystallinity The crystal melting energy of polyethylene having 100% crystal component and the melting peak energy of the obtained copolymer were measured, and the crystallinity was calculated from the energy ratio between polyethylene and the copolymer. The melting peak energy was measured with a differential scanning calorimeter (DSC, manufactured by TA Instruments Japan, "DSCQ2000").

(7) Confirmation of main chain structure ¹³ C-NMR spectrum was measured for the synthesized copolymer.

<Evaluation>
1. Abrasion resistance With respect to the obtained vulcanized rubber, the amount of abrasion at a slip ratio of 60% at room temperature is measured using a Lambourn abrasion tester (manufactured by A&D).
The reciprocal of the wear amount of the vulcanized rubber of Comparative Example 1 was set as 100 and expressed as an index. The larger the index value, the smaller the amount of wear of the vulcanized rubber, indicating that the tire using the vulcanized rubber has excellent wear resistance.

2. Fuel economy The loss coefficient (tan δ) of the obtained vulcanized rubber was measured using a viscoelasticity measuring device (manufactured by Rheometrics) under the conditions of temperature 60° C., strain 5% and frequency 15 Hz. The value of tan δ obtained was expressed as an index with the value of Comparative Example 1 being 100. The larger index value indicates that the tire using the vulcanized rubber has excellent fuel economy and is excellent.

3. Workability (unvulcanized viscosity)
According to JIS-K6300-1:2001, using a Mooney viscometer (RPA manufactured by Monsanto Co., Ltd.) and an L-type rotor, the Mooney viscosity [ML ₁₊₄ /130°C] of the rubber composition was measured under the condition of 130°C. It was measured.
The Mooney viscosity value of the obtained rubber composition was indexed with the value of Comparative Example 1 being 100. It should be noted that the larger the value of the workability index, the better the flowability of the rubber composition, and the better the workability of the rubber composition.

4. Balance of wear resistance, low fuel consumption, and workability A balance index was calculated by the following formula.
Balance index = (wear resistance index + fuel efficiency index + workability index)/3
The larger the balance index, the better the balance between the wear resistance and fuel economy of the tire and the workability of the rubber composition. The allowable range is 103 or more.

As can be seen from Table 1, the rubber compositions of Comparative Examples 1 to 3 containing no multi-component copolymer have an index of more than 100 in terms of tire wear resistance, fuel economy and workability of the rubber composition. Such an excellent evaluation result was not obtained. The rubber composition of Comparative Example 4 in which the content of carbon black in the rubber composition is too large and the rubber composition of Comparative Example 5 in which the content ratio of the carbon black in the filler is too small even if it contains a multi-component copolymer, The fuel economy of the tire and the workability of the rubber composition were not excellent.
On the other hand, in each of the rubber compositions of Examples, all of the wear resistance of the tire, the fuel economy and the workability of the rubber composition were 100 or more, and the index was one or more in the evaluation. Excellent results exceeding 100 were shown. Therefore, it can be seen that the examples are excellent in the balance of wear resistance of the ear, fuel efficiency and workability of the rubber composition.

Claims (14)

A rubber component containing a multicomponent copolymer containing a conjugated diene unit, a non-conjugated olefin unit, and an aromatic vinyl unit,
Including a filler containing carbon black,
The content of the carbon black is 30 parts by mass or more and 60 parts by mass or less with respect to 100 parts by mass of the rubber component, and the content of the carbon black in the filler is 52% by mass or more and 90% by mass or less. Rubber composition for heavy duty tires. The rubber component further contains natural rubber, the content of the multicomponent copolymer in the rubber component is 5 mass% or more and 95 mass% or less, the content of the natural rubber in the rubber component is 5 mass% % Or more and 95 mass% or less, The rubber composition for heavy duty tires according to claim 1. The rubber composition for heavy-duty tires according to claim 1 or 2, wherein the filler further contains 5 parts by mass or more and 28 parts by mass or less of silica with respect to 100 parts by mass of the rubber component. In the multi-component copolymer, the content of the conjugated diene unit is 1 to 50 mol%, the content of the non-conjugated olefin unit is 40 to 97 mol%, and the content of the aromatic vinyl unit is 2 to 35 mol%. %, The rubber composition for heavy duty tires according to any one of claims 1 to 3. The heavy-duty tire according to any one of claims 1 to 4, wherein the multicomponent copolymer has an endothermic peak energy measured by a differential scanning calorimeter (DSC) at 0 to 120°C of 10 to 150 J/g. Rubber composition. The rubber composition for heavy-duty tires according to any one of claims 1 to 5, wherein the multi-component copolymer has a melting point of 30 to 130°C measured by a differential scanning calorimeter (DSC). The rubber composition for heavy-duty tires according to any one of claims 1 to 6, wherein the multi-component copolymer has a glass transition temperature of 0°C or lower measured by a differential scanning calorimeter (DSC). The rubber composition for heavy-duty tires according to any one of claims 1 to 7, wherein the multi-component copolymer has a crystallinity of 0.5 to 50%. The rubber composition for heavy-duty tires according to any one of claims 1 to 8, wherein the multi-component copolymer has a main chain consisting only of an acyclic structure. The rubber composition for heavy duty tires according to any one of claims 1 to 9, wherein the non-conjugated olefin unit is an acyclic non-conjugated olefin unit. The rubber composition for heavy-duty tires according to claim 10, wherein the non-cyclic non-conjugated olefin unit is composed of only ethylene units. The rubber composition for a heavy duty tire according to claim 1, wherein the aromatic vinyl unit contains a styrene unit. The heavy duty tire rubber composition according to any one of claims 1 to 12, wherein the conjugated diene unit contains at least one selected from the group consisting of a 1,3-butadiene unit and an isoprene unit. A heavy load tire using the rubber composition for a heavy load tire according to claim 1.