JP2021088657A - Rubber composition and tire - Google Patents

Abstract

To provide a rubber composition that has excellent dispersibility of a reinforcement filler, and a tire produced using the rubber composition.SOLUTION: A rubber composition contains a rubber component with a weight average molecular weight of 150,000 or more, a reinforcement filler containing at least one selected from the group consisting of carbon black and silica, modified isoprene polymer, and modified butadiene polymer.SELECTED DRAWING: Figure 1

Description

The present invention relates to rubber compositions and tires.

Generally, a reinforcing filler such as carbon black or silica is blended in a rubber composition used for a tire or the like. On the other hand, due to the interaction between the reinforcing fillers, the reinforcing fillers may aggregate in the rubber composition and sufficient properties may not be obtained.

Under such circumstances, for example, Patent Document 1 discloses a modified butadiene polymer as a compounding agent for a rubber composition containing a reinforcing filler.

JP-A-2018-188598

In recent years, as the required performance for rubber materials has increased, the dispersibility of the reinforcing filler after vulcanization with respect to the rubber composition containing the reinforcing filler (hereinafter, "the reinforcing filler after vulcanization" Further improvement of "dispersibility" (also referred to simply as "dispersibility of the reinforcing filler" or "dispersibility") is required.
When the present inventors examined the dispersibility of the rubber composition described in Patent Document 1, it became clear that further improvement is desirable in consideration of the required performance that will be further increased in the future.

Therefore, in view of the above circumstances, it is an object of the present invention to provide a rubber composition having excellent dispersibility of a reinforcing filler and a tire manufactured by using the rubber composition.

As a result of diligent studies on the above problems, the present inventors have found that the above problems can be solved by using the modified isoprene polymer and the modified butadiene polymer in combination, and have reached the present invention.
That is, the present inventors have found that the above problems can be solved by the following configuration.

(1) Contains a reinforcing filler containing a rubber component having a weight average molecular weight of 150,000 or more, at least one selected from the group consisting of carbon black and silica, a modified isoprene polymer, and a modified butadiene polymer. Rubber composition.
(2) The modified isoprene polymer has an alkoxysilyl group or a functional group containing a nitrogen atom and an alkoxysilyl group at the terminal or side chain, and has a weight average molecular weight of 1,000 or more and less than 1.5 million. It is a modified isoprene polymer and
The modified butadiene polymer has an alkoxysilyl group or a functional group containing a nitrogen atom and an alkoxysilyl group at the terminal or side chain, and has a weight average molecular weight of 1,000 or more and less than 1.5 million. The rubber composition according to (1) above, which is a polymer.
(3) The content of the modified isoprene polymer is 1 to 50 parts by mass with respect to 100 parts by mass of the rubber component.
The rubber composition according to (1) or (2) above, wherein the content of the modified butadiene polymer is 1 to 50 parts by mass with respect to 100 parts by mass of the rubber component.
(4) The rubber composition according to any one of (1) to (3) above, wherein the content of the reinforcing filler is 5 to 150 parts by mass with respect to 100 parts by mass of the rubber component.
(5) The rubber composition according to any one of (1) to (4) above, wherein the reinforcing filler is at least one selected from the group consisting of carbon black and silica.
(6) Further contains a silane coupling agent,
The reinforcing filler contains at least silica and
The rubber composition according to any one of (1) to (5) above, wherein the content of the silane coupling agent is 1 to 20% by mass with respect to the content of the silica.
(7) A tire manufactured by using the rubber composition according to any one of (1) to (6) above.

As shown below, according to the present invention, it is possible to provide a rubber composition having excellent dispersibility of a reinforcing filler and a tire manufactured by using the rubber composition.

It is a partial cross-sectional schematic diagram of the tire which shows an example of embodiment of the tire of this invention.

The rubber composition of the present invention and the tire of the present invention will be described below.
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.
In addition, each component contained in the rubber composition of the present invention may be used alone or in combination of two or more. Here, when two or more kinds of each component are used in combination, the content of the component means the total content unless otherwise specified.

[1] Rubber Composition The rubber composition of the present invention (hereinafter, also simply referred to as “the composition of the present invention”) is selected from the group consisting of a rubber component having a weight average molecular weight of 150,000 or more, carbon black and silica. It is a rubber composition containing a reinforcing filler containing at least one of these, a modified isoprene polymer, and a modified butadiene polymer.

Hereinafter, each component contained in the composition of the present invention will be described.

[Rubber component]
As described above, the composition of the present invention contains a rubber component.
The rubber component is not particularly limited as long as it is a rubber component having a weight average molecular weight (Mw) of 150,000 or more. However, the rubber component does not include the modified isoprene polymer described later and the modified butadiene polymer described later.

The rubber component is preferably a diene-based rubber because it is excellent in processability and dispersibility, and is also excellent in low heat generation, elongation at break, breaking strength and wear resistance after vulcanization.
Hereinafter, "excellent in workability and dispersibility, and excellent in low heat generation, elongation at break, fracture strength and wear resistance after vulcanization" is also referred to as "the effect of the present invention is more excellent".
Specific examples of the diene rubber include natural rubber (NR), isoprene rubber (IR), butadiene rubber (BR), styrene-butadiene rubber (SBR), acrylonitrile-butadiene copolymer rubber (NBR), butyl rubber (IIR), and the like. Examples thereof include butyl halide rubber (Br-IIR, Cl-IIR) and chloroprene rubber (CR). Of these, natural rubber is preferable because the effects of the present invention are more excellent.
When the rubber component contains natural rubber, the content of the natural rubber in the rubber component is preferably 50% by mass or more, preferably 70% by mass or more, for the reason that the effect of the present invention is more excellent. Is more preferable, and 90% by mass or more is further preferable. The upper limit of the content of natural rubber in the rubber component is not particularly limited and is 100% by mass.

[Molecular weight]

<Weight average molecular weight>
As described above, the weight average molecular weight (Mw) of the rubber component is 150,000 or more. The Mw of the rubber component is preferably 200,000 to 1,000,000, more preferably 250,000 to 2,000,000, for the reason that the effects of the present invention are more excellent.

<Number average molecular weight>
The weight average molecular weight (Mn) of the rubber component is not particularly limited, but is preferably 100,000 to 5,000,000, preferably 120,000 to 1,000, for the reason that the effects of the present invention are more excellent. It is more preferably 000.

<Measurement method>
In the present specification, the weight average molecular weight (Mw) and the number average molecular weight (Mn) are standard polystyrene-equivalent values obtained by gel permeation chromatography (GPC) measurement under the following conditions.
・ Solvent: Tetrahydrofuran ・ Detector: RI detector

[Reinforcing filler]
As described above, the composition of the present invention contains a reinforcing filler containing at least one selected from the group consisting of carbon black and silica.
The reinforcing filler preferably contains both carbon black and silica for the reason that the effects of the present invention are more excellent.

〔Carbon black〕
The composition of the present invention preferably contains carbon black as a reinforcing filler for the reason that the effects of the present invention are more excellent. As the carbon black, one kind of carbon black may be used alone, or two or more kinds of carbon black may be used in combination.
The carbon black is not particularly limited, and for example, various grades such as SAF-HS, SAF, ISAF-HS, ISAF, ISAF-LS, IISAF-HS, HAF-HS, HAF, HAF-LS, FEF, GPF, SRF and the like. Can be used.
The nitrogen adsorption specific surface area (N ₂ SA) of the carbon black is not particularly limited, but is preferably 50 to ²⁰⁰ m 2 / g, ^{preferably 70 to 150 m 2} / g, for the reason that the effect of the present invention is more excellent. Is more preferable.
Here, the nitrogen adsorption specific surface area (N ₂ SA) is the amount of nitrogen adsorbed on the surface of carbon black according to JIS K6217-2: 2001 "Part 2: How to obtain the specific surface area-Nitrogen adsorption method-Single point method". It is a measured value.

In the composition of the present invention, the content of carbon black is not particularly limited, but it is preferably 1 to 100 parts by mass with respect to 100 parts by mass of the above-mentioned rubber component for the reason that the effect of the present invention is more excellent. More preferably, it is 2 to 10 parts by mass.

〔silica〕
The composition of the present invention preferably contains silica as a reinforcing filler for the reason that the effects of the present invention are more excellent.
The silica is not particularly limited, and any conventionally known silica can be used.
Examples of the silica include wet silica, dry silica, fumed silica, and diatomaceous earth. As the silica, one type of silica may be used alone, or two or more types of silica may be used in combination.

The cetyltrimethylammonium bromide (CTAB) adsorption specific surface area (hereinafter, “CTAB adsorption specific surface area” is also simply referred to as “CTAB”) of the silica is not particularly limited, but 100 to 300 m for the reason that the effect of the present invention is more excellent. it is preferably ² / g, more preferably 185 m ² / g or more.
Here, the CTAB adsorption specific surface area is a value obtained by measuring the amount of CTAB adsorbed on the silica surface according to JIS K6217-3: 2001 "Part 3: How to obtain the specific surface area-CTAB adsorption method".

Nitrogen adsorption specific surface area of the silica _(N 2 SA) is not particularly limited, because the effects such as the present invention is more excellent, is preferably 100 to 300 m ² / g, it is 194m ² / g or more More preferred.
Here, N ₂ SA is a substitute property of the surface area that silica can be used for adsorption with rubber molecules, and the amount of nitrogen adsorbed on the silica surface is determined by JIS K6217-2: 2001 "Part 2: How to obtain the specific surface area-" It is a value measured according to "Nitrogen adsorption method-single point method".

The ratio of the silica nitrogen adsorption specific surface area to the CTAB adsorption specific surface area of silica (N ₂ SA / CTAB) is not particularly limited, but is preferably 0.9 to 1.4 for the reason that the effect of the present invention is more excellent. ..

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 10 to 150 parts by mass with respect to 100 parts by mass of the rubber component described above. More preferably, it is 30 to 100 parts by mass.

<Content>
In the composition of the present invention, the content of the reinforcing filler is not particularly limited, but for the reason that the effect of the present invention is more excellent, the content is 5 to 150 parts by mass with respect to 100 parts by mass of the rubber component described above. Is preferable, and it is more preferably 30 to 100 parts by mass.
When the composition of the present invention contains two or more kinds of reinforcing fillers, the content of the reinforcing fillers means the total content.

[Modified isoprene polymer]
As described above, the composition of the present invention contains a modified isoprene polymer (hereinafter, also referred to as “modified IR”).
The modified IR is an isoprene polymer having a functional group.

[Functional group]
The functional group possessed by the modified IR is not particularly limited, but from the amino group, the hydroxy group, the epoxy group, the alkylsilyl group, the alkoxysilyl group, the carboxyl group and the specific functional group described later, for the reason that the effect of the present invention is more excellent. At least one functional group selected from the above group is preferable, an alkoxysilyl group (particularly a triethoxysilyl group) and a specific functional group described later are more preferable, and a specific functional group described later is further preferable.
The modified IR may have the functional group at the end or the side chain, but it is preferable to have the functional group at the end for the reason that the effect of the present invention is more excellent.

[Molecular weight]

<Weight average molecular weight>
The weight average molecular weight (Mw) of the modified IR is not particularly limited, but is preferably 1,000 to 1,000,000, preferably 20,000 or more and less than 150,000, for the reason that the effect of the present invention is more excellent. More preferably, it is more preferably 70,000 or more and less than 150,000.

<Number average molecular weight>
The number average molecular weight (Mn) of the modified IR is not particularly limited, but is preferably 1,000 to 5,000,000, preferably 10,000 or more and less than 150,000, for the reason that the effect of the present invention is more excellent. More preferably, it is more preferably 70,000 or more and less than 150,000.

<Molecular weight distribution>
The molecular weight distribution (Mw / Mn) of the modified IR is not particularly limited, but is preferably 2.0 or less, more preferably 1.7 or less, for the reason that the effect of the present invention is more excellent. It is more preferably 5 or less, and particularly preferably 1.3 or less.
The lower limit is not particularly limited, but is usually 1.0 or more.

[Micro structure]
<1,2-structure and 3,4-structure>
In the modified IR, the ratio of 1,2-structure and 3,4-structure is not particularly limited, but is preferably 0 to 10 mol%, preferably 0 to 5 mol%, for the reason that the effect of the present invention is more excellent. Is more preferable.
Here, the ratio of the 1,2-structure means the ratio (mol%) of the repeating units having the 1,2-structure among the repeating units derived from isoprene. The ratio of the 3,4-structure means the ratio (mol%) of the repeating units having the 3,4-structure among the repeating units derived from isoprene.

<1,4-Transformer structure>
In the modified IR, the ratio of the 1,4-trans structure is not particularly limited, but is preferably 2 to 90 mol%, more preferably 5 to 70 mol% for the reason that the effect of the present invention is more excellent. preferable.
Here, the ratio of the 1,4-trans structure means the ratio (mol%) of the repeating units having the 1,4-trans structure to all the repeating units derived from isoprene.

<1,4-cis structure>
In the modified IR, the ratio of the 1,4-cis structure is not particularly limited, but is preferably 10 to 98 mol%, more preferably 30 to 98 mol%, for the reason that the effect of the present invention is more excellent. preferable.
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 isoprene.

In addition, hereinafter, "total ratio of 1,2-structure and 3,4-structure (mol%), ratio of 1,4-trans structure (mol%), ratio of 1,4-cis structure (mol%)) Is also expressed as "1,2- and 3,4- / trans / cis".

〔Glass-transition temperature〕
The glass transition temperature (Tg) of the modified IR is not particularly limited, but is preferably −100 to −40 ° C., more preferably −90 to −50 ° C. for the reason that the effect of the present invention is more excellent. , −85 to −60 ° C., more preferably.
In the present specification, the glass transition temperature (Tg) is measured at a heating rate of 10 ° C./min using a differential scanning calorimeter (DSC) and calculated by the midpoint method.

〔viscosity〕
The viscosity of the modified IR is not particularly limited, but it is preferably more than 2,000 Pa · s, more preferably 3,000 to 100,000 Pa · s, for the reason that the effect of the present invention is more excellent.
The viscosity of the isoprene polymer before modification of the modified IR is not particularly limited, but is preferably more than 800 Pa · s, preferably 1,200 to 8,000 Pa · s, for the reason that the effect of the present invention is more excellent. Is more preferable.
Further, the viscosity of the modified IR is preferably 150 to 240% with respect to the viscosity of the isoprene polymer before modification because the effect of the present invention is more excellent. Hereinafter, the viscosity after modification with respect to the viscosity before modification is also referred to as "viscosity (after modification / before modification)".
In this specification, the viscosity is measured using a cone plate type viscometer according to JIS K5600-2-3. Further, it is assumed that the viscosity is measured under the condition of 40 ° C.

[Specific modified isoprene polymer]
The modified IR is an isoprene polymer having a functional group containing a nitrogen atom and a silicon atom (hereinafter, also referred to as “specific functional group”) at the end (hereinafter, “specific modified isoprene polymer”) for the reason that the effect of the present invention is more excellent. Or "specific modified IR").

<Specific functional group>
As described above, the specific modified IR has a functional group (specific functional group) containing a nitrogen atom and a silicon atom at the end. The specific modified IR may have a specific functional group at at least one terminal of the specific modified IR.

(Preferable aspect)
The specific functional group is not particularly limited as long as it is a functional group containing a nitrogen atom and a silicon atom, but for the reason that the effect of the present invention is more excellent, the nitrogen atom is an amino group (-NR ₂ : R is a hydrogen atom or a hydrocarbon group). ), And preferably contains a silicon atom as a hydrocarbyloxysilyl group (≡SiOR: R is a hydrocarbon group).

The specific functional group is preferably a group represented by the following formula (M) for the reason that the effect of the present invention is more excellent.

In the above formula (M), R ₁ and R ₂ each independently represent a hydrogen atom or a substituent.
In the above formula (M), L represents a single bond or a divalent organic group.

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, a phosphino group and a phosphinyl. Examples thereof include a group, a silyl group, and a hydrocarbon group which may have a hetero atom.
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 (M), R ₁ has a hydrogen atom, an alkyl group (preferably 1 to 10 carbon atoms), and an alkylsilyl group (preferably 1 to 10 carbon atoms) because the effect of the present invention is more excellent. ), It is preferably an aromatic hydrocarbon group (preferably 6 to 18 carbon atoms), and more preferably a hydrogen atom.
A plurality of R _1s may be the same or different.
When a plurality of R ₁ are different, the combination of a plurality of R ₁ is, for reasons effect, etc. of the present invention is more excellent, and a hydrogen atom, an alkyl group (preferably, 1 to 10 carbon atoms), an alkylsilyl group (preferably , 1 to 10 carbon atoms) or an aromatic hydrocarbon group (preferably 6 to 18 carbon atoms), and a combination of a hydrogen atom and an alkylsilyl group (preferably 1 to 10 carbon atoms) is more preferable. A combination of a hydrogen atom and a trialkylsilyl group (preferably 1 to 10 carbon atoms) is more preferable.

R ₂ is preferably a hydrocarbyloxy group (-OR group: R is a hydrocarbon group) and is an alkoxy group (preferably having 1 to 10 carbon atoms) because the effect of the present invention is more excellent. Is more preferable.

As described above, in the above formula (M), L represents a single bond or a divalent organic group.
Examples of the divalent organic group include an aliphatic hydrocarbon group (for example, an alkylene group, preferably 1 to 10 carbon atoms), an aromatic hydrocarbon group (for example, an arylene group, preferably 6 to 18 carbon atoms). -O-, -S-, -SO _2- , -N (R)-(R: alkyl group), -CO-, -NH-, -COO-, -CONH-, or a group combining these (for example, , alkyleneoxy radical _{(-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 having 1 to 10 carbon atoms) for the reason that the effects of the present invention are more excellent.

In the above equation (M), n represents an integer of 0 to 2.
n is preferably 2 for the reason that the effect of the present invention is more excellent.

In the above formula (M), m represents an integer of 1 to 3.
m is preferably 1 for the reason that the effect of the present invention is more excellent.

In the above equation (M), n and m satisfy the relational expression of n + m = 3.

In the above formula (M), * represents a bonding position.

<Manufacturing method>
The method for producing the specific modified IR is not particularly limited, and a conventionally known method can be used. The method for limiting the molecular weight and the molecular weight distribution in a specific range is not particularly limited, and examples thereof include a method for adjusting the amount ratio of the initiator, the monomer, and the terminator, the reaction temperature, the rate at which the initiator is added, and the like.

In the method for producing the specific modified IR, isoprene is polymerized with an organic lithium compound because the effect of the present invention is more excellent with respect to the obtained composition, and then an electrophile containing a nitrogen atom and a silicon atom is used. The method for terminating the polymerization (hereinafter, also referred to as “method 1 of the present invention”) is preferable. Hereinafter, "the effect of the present invention is more excellent with respect to the obtained composition" is also simply referred to as "the effect of the present invention is more excellent".

(Organolithium compound)
The organic lithium compound is not particularly limited, and specific examples thereof include monoorganic lithium compounds such as n-butyllithium, sec-butyllithium, tert-butyllithium, n-propyllithium, iso-propyllithium, and benzyllithium; 1,4-dilithiobutane, 1,5-dilithiopentane, 1,6-dilithiohexane, 1,10-dilithiodecane, 1,1-dilithiodiphenylene, dilithiopolybutadiene, dilithiopolyisoprene, 1,4-dilithio Benzene, 1,2-dilithio-1,2-diphenylethane, 1,4-dilithio-2-ethylcyclohexane, 1,3,5-trilithiobenzene, 1,3,5-trilithio-2,4,6- Examples thereof include polyfunctional organic lithium compounds such as triethylbenzene. Of these, 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 organic lithium compound used is not particularly limited, but it is preferably 0.001 to 10 mol% with respect to isoprene for the reason that the effect of the present invention is more excellent.

(Polymerization of isoprene)
The method for polymerizing isoprene using an organic lithium compound is not particularly limited, but the above-mentioned organic lithium compound is added to an organic solvent solution containing isoprene, and the temperature range is 0 to 120 ° C (preferably 30 to 100 ° C). Examples include a method of stirring.

(Specific electrophile)
In Method 1 of the present invention, the polymerization of isoprene is stopped by using an electrophile containing a nitrogen atom and a silicon atom (hereinafter, also referred to as “specific electrophile”). By terminating the polymerization with a specific electrophile, an isoprene polymer (specifically modified IR) having the above-mentioned specific functional group at the end can be obtained.
The specific electrophilic agent is not particularly limited as long as it is a compound containing a nitrogen atom and a silicon atom, but for the reason that the effect of the present invention is more excellent, the nitrogen atom is an amino group (-NR ₂ : R is a hydrogen atom or a hydrocarbon group). ), And preferably contains a silicon atom as a hydrocarbyloxysilyl group (≡SiOR: R is a hydrocarbon group).

The specific electrophile is preferably silazane, more preferably cyclic silazane, for the reason that the effects of the present invention are more excellent. 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 effects of the present invention are more excellent.

In the above formula (S), R _{1 to} R ₃ independently represent a hydrogen atom or a substituent. Specific examples and preferred embodiments of the substituent are the same as _{those of R 1} and R _{2 in the above formula (M).}
In the above formula (S), L represents a divalent organic group. Specific examples and preferred embodiments of the divalent organic group are the same as L in the above-mentioned formula (M).

In the above formula (S), R ₁ has an alkyl group (preferably 1 to 10 carbon atoms), an alkylsilyl group (preferably 1 to 10 carbon atoms), and an aromatic group because the effects of the present invention are more excellent. It is preferably a group hydrocarbon group (preferably 6 to 18 carbon atoms), and more preferably an alkylsilyl group.

In the above formula (S), R ₂ and R ₃ are preferably hydrocarbyloxy groups (-OR group: R is a hydrocarbon group) independently of each other because the effects of the present invention are more excellent, and alkoxy. It is more preferably a group (preferably 1 to 10 carbon atoms).

In the above formula (S), L is preferably an alkylene group (preferably 1 to 10 carbon atoms, more preferably 2 to 8 carbon atoms, still more preferably 3 to 5 carbon atoms) for the reason that the effect of the present invention is more excellent. preferable.

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.

The amount of the specific electrophile with respect to the organolithium compound is not particularly limited, but for the reason that the effect of the present invention is more excellent, the molar ratio is preferably 0.1 to 10, and more preferably 1 to 7. preferable.

〔Content〕
In the composition of the present invention, the content of the modified IR is preferably 0.1 to 50 parts by mass with respect to 100 parts by mass of the rubber component, for the reason that the effect of the present invention is more excellent. More preferably, it is by mass.

[Modified Butadiene Polymer]
As described above, the composition of the present invention contains a modified butadiene polymer (hereinafter, also referred to as "modified BR").
The modified BR is a butadiene polymer having a functional group.

[Functional group]
Specific examples and preferred embodiments of the functional group of the modified BR are the same as those of the modified IR described above.
The modified BR may have the functional group at the end or the side chain, but it is preferable to have the functional group at the end for the reason that the effect of the present invention is more excellent.

[Molecular weight]

<Weight average molecular weight>
The weight average molecular weight (Mw) of the modified BR is not particularly limited, but is preferably 1,000 to 1,000,000, preferably 2,000 or more and less than 150,000, for the reason that the effect of the present invention is more excellent. It is more preferably 5,000 to 100,000, and particularly preferably 5,000 to 20,000.

<Number average molecular weight>
The number average molecular weight (Mn) of the modified BR is not particularly limited, but is preferably 1,000 to 5,000,000, preferably 2,000 or more and less than 150,000, for the reason that the effect of the present invention is more excellent. It is more preferably 5,000 to 100,000, and particularly preferably 5,000 to 20,000.

<Molecular weight distribution>
The molecular weight distribution (Mw / Mn) of the modified BR is not particularly limited, but is preferably 2.0 or less, more preferably 1.7 or less, for the reason that the effect of the present invention is more excellent. It is more preferably 5 or less, and particularly preferably 1.3 or less.
The lower limit is not particularly limited, but is usually 1.0 or more.

[Micro structure]
<Vinyl structure>
In the modified BR, the ratio of the vinyl structure (vinyl unit content) is not particularly limited, but it is preferably 10 to 50 mol%, preferably 20 to 40 mol%, for the reason that the effect of the present invention is more excellent. Is more preferable.
Here, the ratio of the vinyl structure means the ratio (mol%) of the repeating units having a vinyl structure to the repeating units derived from butadiene.

<1,4-Transformer structure>
In the modified BR, the ratio of the 1,4-trans structure is not particularly limited, but is preferably 10 to 70 mol%, more preferably 30 to 50 mol%, for the reason that the effect of the present invention is more excellent. preferable.
Here, the ratio of the 1,4-trans structure means the ratio (mol%) of the repeating units having the 1,4-trans structure to all the repeating units derived from butadiene.

<1,4-cis structure>
In the modified BR, the ratio of the 1,4-cis structure is not particularly limited, but is preferably 10 to 50 mol%, more preferably 20 to 40 mol%, for the reason that the effect of the present invention is more excellent. preferable.
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 butadiene.

〔Glass-transition temperature〕
The glass transition temperature (Tg) of the modified BR is not particularly limited, but is preferably −100 to −60 ° C., more preferably −90 to −70 ° C. for the reason that the effect of the present invention is more excellent. , −85 to −75 ° C., more preferably.
The glass transition temperature (Tg) is measured at a heating rate of 10 ° C./min using a differential scanning calorimeter (DSC) and calculated by the midpoint method.

〔viscosity〕
The viscosity of the modified BR is not particularly limited, but is preferably 1,000 to 10,000 mPa · s, more preferably 3,000 to 6,000 mPa · s, for the reason that the effect of the present invention is more excellent. preferable.
The viscosity of the butadiene polymer before modification of the modified BR is not particularly limited, but is preferably 500 to 5,000 mPa · s, preferably 1,500 to 3,000 mPa, for the reason that the effect of the present invention is more excellent. -S is more preferable.
The viscosity of the modified BR is preferably 150 to 240% of the viscosity of the butadiene polymer before modification because the effects of the present invention are more excellent.
The viscosity shall be measured using a cone plate type viscometer according to JIS K5600-2-3.

[Specific modified butadiene polymer]
The modified BR is a butadiene polymer having a functional group containing a nitrogen atom and a silicon atom (hereinafter, also referred to as “specific functional group”) at the end (hereinafter, “specific modified butadiene polymer”) for the reason that the effect of the present invention is more excellent. "Or" specific modified BR ").

<Specific functional group>
Specific examples and preferred embodiments of the specific functional group are the same as those of the specific modified IR described above.

<Manufacturing method>
The method for producing the specific modified BR is not particularly limited, and a conventionally known method can be used. The method for limiting the molecular weight and the molecular weight distribution in a specific range is not particularly limited, and examples thereof include a method for adjusting the amount ratio of the initiator, the monomer, and the terminator, the reaction temperature, the rate at which the initiator is added, and the like.

In the method for producing the specific modified BR, butadiene is polymerized with an organic lithium compound for the reason that the effect of the present invention is more excellent with respect to the obtained composition, and then an electrophile containing a nitrogen atom and a silicon atom is used. It is preferable that the method is used to terminate the polymerization (hereinafter, also referred to as “method 2 of the present invention”). Hereinafter, "the effect of the present invention is more excellent with respect to the obtained composition" is also simply referred to as "the effect of the present invention is more excellent".

(Organolithium compound)
Specific examples and preferred embodiments of the organolithium compound are the same as those of the specific modified IR described above.

(Polymerization of butadiene)
The method for polymerizing butadiene using an organic lithium compound is not particularly limited, but the above-mentioned organic lithium compound is added to an organic solvent solution containing butadiene, and the temperature range is 0 to 120 ° C (preferably 30 to 100 ° C). Examples include a method of stirring.

(Specific electrophile)
Specific examples and preferred embodiments of the specific electrophile are the same as those of the specific modified IR described above.

A preferred embodiment of the amount of the specific electrophile with respect to the organolithium compound is the same as the specific modified IR described above.

〔Content〕
In the composition of the present invention, the content of the modified BR is preferably 0.1 to 50 parts by mass with respect to 100 parts by mass of the rubber component, for the reason that the effect of the present invention is more excellent. More preferably, it is by mass.

[Total content of modified IR and modified BR]
In the composition of the present invention, the total content of the above-mentioned modified IR and the above-mentioned modified BR is 1 to 100 parts by mass with respect to 100 parts by mass of the above-mentioned rubber component because the effect of the present invention is more excellent. It is preferably 2 to 20 parts by mass, more preferably 4 to 10 parts by mass.

In the composition of the present invention, the total content of the above-mentioned modified IR and the above-mentioned modified BR is based on the above-mentioned content of the reinforcing filler (particularly silica) because the effect of the present invention is more excellent. , 1 to 50% by mass, more preferably 3 to 40% by mass, further preferably 5 to 35% by mass, particularly preferably 7 to 30% by mass, and 10 to 10% by mass. It is particularly preferably 25% by mass, and most preferably 15 to 20% by mass.

[Amount ratio of modified IR and modified BR]
In the composition of the present invention, the ratio of the above-mentioned modified BR content to the above-mentioned modified IR content (modified IR / modified BR) is 10 to 500% by mass because the effect of the present invention is more excellent. It is preferably 20 to 400% by mass, more preferably 50 to 200% by mass, and particularly preferably 80 to 120% by mass.

[Arbitrary component]
The composition of the present invention may contain components (arbitrary components) other than the above-mentioned components, if necessary.
Such components include, for example, silane coupling agents, terpene resins (preferably aromatic modified terpene resins), thermosetting microcapsules, zinc oxide (zinc oxide), stearic acid, antioxidants, waxes, processing. Auxiliary agents, process oils, liquid polymers, thermosetting resins, vulcanizing agents (eg, sulfur), vulcanization accelerators, various additives commonly used in rubber compositions such as vulcanization activators, etc. Be done.

〔Silane coupling agent〕
The composition of the present invention preferably contains a silane coupling agent for the reason that the effects of the present invention are more excellent. In particular, when the above-mentioned reinforcing filler contains at least silica, the composition of the present invention preferably contains a silane coupling agent for the reason that the effects of the present invention are more excellent.

The silane coupling agent is not particularly limited as long as it is a silane compound having a hydrolyzable group and an organic functional group.
The hydrolyzable group is not particularly limited, and examples thereof include an alkoxy group, a phenoxy group, a carboxyl group, and an alkenyloxy group. Of these, an alkoxy group is preferable because the effect of the present invention is more excellent. When the hydrolyzable group is an alkoxy group, the number of carbon atoms of the alkoxy group is preferably 1 to 16 and more preferably 1 to 4 for the reason that the effect of the present invention is more excellent. Examples of the alkoxy group having 1 to 4 carbon atoms include a methoxy group, an ethoxy group, a propoxy group and the like.

The organic functional group is not particularly limited, but is preferably a group capable of forming a chemical bond with an organic compound, for example, an epoxy group, a vinyl group, an acryloyl group, a methacryloyl group, an amino group, a sulfide group, a mercapto group, or a block. Examples thereof include a mercapto group (protected mercapto group) (for example, an octanoylthio group), and among them, a sulfide group (particularly, a disulfide group and a tetrasulfide group), a mercapto group, and a block mercapto for the reason that the effect of the present invention is more excellent. Groups are preferred.
One type of silane coupling agent may be used alone, or two or more types may be used in combination.

The silane coupling agent is preferably a sulfur-containing silane coupling agent because the effects of the present invention are more excellent.

Specific examples of the above silane coupling agent include bis (3-triethoxysilylpropyl) tetrasulfide, bis (3-trimethoxysilylpropyl) tetrasulfide, bis (3-triethoxysilylpropyl) disulfide, and mercaptopropyltrimethoxy. Silane, mercaptopropyl triethoxysilane, 3-trimethoxysilylpropyl-N, N-dimethylthiocarbamoyl-tetrasulfide, trimethoxysilylpropyl-mercaptobenzothiazole tetrasulfide, triethoxysilylpropyl-methacrylate-monosulfide, dimethoxymethylsilyl Examples thereof include propyl-N, N-dimethylthiocarbamoyl-tetrasulfide, 3-octanoylthio-1-propyltriethoxysilane, etc., and one of them may be used alone or two or more thereof may be used in combination. ..

<Content>
In the composition of the present invention, the content of the silane coupling agent is not particularly limited, but for the reason that the effect of the present invention is more excellent, the content is 1 to 20 parts by mass with respect to 100 parts by mass of the above-mentioned rubber component. Is preferable, and it is more preferably 2 to 10 parts by mass.

Further, in the composition of the present invention, the content of the silane coupling agent is preferably 1 to 20% by mass with respect to the above-mentioned silica content for the reason that the effect of the present invention is more excellent. More preferably, it is ~ 15% by mass.

[2] Tire The tire of the present invention is a tire manufactured by using the composition of the present invention described above. The tire of the present invention is preferably a pneumatic tire and can be filled with an inert gas such as air or nitrogen or other gas. Further, the tire of the present invention is preferably a tire having a tire tread portion manufactured by using the composition of the present invention.
FIG. 1 shows a schematic partial cross-sectional view of a tire showing an example of an embodiment of the tire of the present invention, but the tire of the present invention is not limited to the aspect shown in FIG.

In FIG. 1, reference numeral 1 represents a bead portion, reference numeral 2 represents a sidewall portion, and reference numeral 3 represents a tire tread portion.
Further, a carcass layer 4 in which a fiber cord is embedded is mounted between the pair of left and right bead portions 1, and the end portion of the carcass layer 4 is placed around the bead core 5 and the bead filler 6 from the inside to the outside of the tire. It is folded back and rolled up.
Further, in the tire tread portion 3, a belt layer 7 is arranged on the outside of the carcass layer 4 over one circumference of the tire.
Further, in the bead portion 1, the rim cushion 8 is arranged at a portion in contact with the rim.
The tire tread portion 3 is formed by the composition of the present invention described above.

The tire of the present invention can be manufactured, for example, according to a conventionally known method. Further, as the gas to be filled in the tire of the present invention, an inert gas such as nitrogen, argon or helium can be used in addition to normal air or air having an adjusted oxygen partial pressure.

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

[Synthesis example]
Specific modified IR1 and 2 and specific modified BR1 and 2 were synthesized as follows.
Since the specific modified IRs 1 and 2 are isoprene polymers having a functional group containing a nitrogen atom and a silicon atom at the end, they correspond to the above-mentioned specific modified IR. Further, since the specific modified BRs 1 and 2 are butadiene polymers having a functional group containing a nitrogen atom and a silicon atom at the end, they correspond to the above-mentioned specific modified BR.

<Specific modified IR1 (50k)>
Add n-BuLi (manufactured by Kanto Chemical Co., Inc .: 1.60 mol / L (hexane solution), 40.0 mL, 64 mmol) to a mixed solution of isoprene (681 g, 10.0 mol) in cyclohexane (4.0 kg) at 50 ° C. The mixture was stirred for 6 hours. After the reaction, N-trimethylsilyl-1,1-dimethoxy-2-azasilacyclopentane (hereinafter, structure) (80 mL, 328 mmol) was added to terminate the polymerization. The resulting solution was removed and concentrated under reduced pressure. The concentrated solution was poured into methanol (5.0 L) to separate the methanol-insoluble component.

As a result, 95% of the isoprene polymer (specifically modified IR1) (Mn = 44,000, Mw = 54,200, Mw / Mn = 1.2) having a functional group represented by the following formula (m1) at the end. Obtained in yield. It was estimated by IR analysis that 1,2- and 3,4- / trans / cis = 7/0/93. The Tg was −61 ° C.

<Specific modified IR2 (100k)>
Add n-BuLi (manufactured by Kanto Chemical Co., Inc .: 1.60 mol / L (hexane solution), 20.0 mL, 32 mmol) to a mixed solution of isoprene (681 g, 10.0 mol) in cyclohexane (4.0 kg) at 50 ° C. The mixture was stirred for 6 hours. After the reaction, N-trimethylsilyl-1,1-dimethoxy-2-azasilacyclopentane (40 mL, 164 mmol) was added to terminate the polymerization. The resulting solution was removed and concentrated under reduced pressure. The concentrated solution was poured into methanol (5.0 L) to separate the methanol-insoluble component. As a result, 97% of the isoprene polymer (specifically modified IR2) (Mn = 84,500, Mw = 105,000, Mw / Mn = 1.2) having a functional group represented by the above formula (m1) at the end. Obtained in yield. It was estimated by IR analysis that 1,2- and 3,4- / trans / cis = 6/0/94. The Tg was −62 ° C.

<Specific modified BR1 (50k)>
n-BuLi (manufactured by Kanto Chemical Co., Inc .: 1.60 mol / L (hexane solution), 30 mL, 48 mmol), 1,3-butadiene (832 g, 15.4 mol) and 2,2-di (2-tetrahydrofuryl) propane ( It was added to a mixed solution of cyclohexane (4.2 kg) of Tokyo Kasei Co., Ltd. (0.1 mL), and the mixture was stirred at room temperature for 6 hours. After the reaction, N-trimethylsilyl-1,1-dimethoxy-2-azasilacyclopentane (60 mL, 246 mmol) was added to terminate the polymerization. The resulting solution was removed and concentrated under reduced pressure. The concentrated solution was poured into methanol (5.0 L) to separate the methanol-insoluble component. As a result, 94% of the butadiene polymer (specifically modified BR1) (Mn = 46,200, Mw = 52,100, Mw / Mn = 1.1) having a functional group represented by the above formula (m1) at the end. Obtained in yield. It was estimated by IR analysis that vinyl / trans / cis = 24/40/36. The Tg was −84 ° C.

<Specific modified BR2 (10k)>
n-BuLi (manufactured by Kanto Chemical Co., Inc .: 1.60 mol / L (hexane solution), 120 mL, 192 mmol), 1,3-butadiene (832 g, 15.4 mol) and 2,2-di (2-tetrahydrofuryl) propane ( It was added to a mixed solution of cyclohexane (4.0 kg) of Tokyo Kasei Co., Ltd. (0.1 mL), and the mixture was stirred at room temperature for 6 hours. After the reaction, N-trimethylsilyl-1,1-dimethoxy-2-azasilacyclopentane (240 mL, 984 mmol) was added to terminate the polymerization. The resulting solution was removed and concentrated under reduced pressure. The concentrated solution was poured into methanol (5.0 L) to separate the methanol-insoluble component. As a result, 91% of the butadiene polymer (specifically modified BR1) (Mn = 9,680, Mw = 9,970, Mw / Mn = 1.0) having a functional group represented by the above formula (m1) at the end. Obtained in yield. It was estimated by IR analysis that vinyl / trans / cis = 28/41/31. The Tg was −83 ° C.

[Preparation of rubber composition]
The components shown in Tables 1 to 6 below were blended in the proportions (parts by mass) shown in the same table.
Specifically, first, among the components shown in Tables 1 to 6 below, the components excluding sulfur, the vulcanization activator and the vulcanization accelerator were mixed in a Banbury mixer at 80 ° C. for 5 minutes. Next, using a roll, sulfur, a vulcanization activator and a vulcanization accelerator were mixed to obtain a rubber composition.

[Pain effect (after vulcanization)]
Each of the obtained rubber compositions (unvulcanized) was press-vulcanized in a mold (15 cm × 15 cm × 0.2 cm) at 160 ° C. for 15 minutes to prepare a vulcanized rubber sheet.
Then, with respect to the produced vulture rubber sheet, a strain shear stress measuring machine (RPA2000, manufactured by α-Technology Co., Ltd.) was used to obtain a strain shear modulus G'of 0.28% strain and a strain shear modulus G of 30.0% strain. ′ And the difference G ′ 0.28 (MPa) − G ′ 30.0 (MPa) were calculated as the Pain effect.
The results are shown in Tables 1-6. The results are expressed as an index with the standard example as 100. The smaller the index, the better the dispersibility of the reinforcing filler.

Details of each component shown in Tables 1 to 6 above are as follows.
-Natural rubber: TSR20 manufactured by VON BUNDIT (weight average molecular weight: 1,890,000)
-Carbon Black: Tokai Carbon Co., Ltd. Seest KH
-Silica: Zeosil Premium 200MP (silica, N ₂ SA = 200m ² / g, CTAB = 200m ² / g, N ₂ SA / CTAB = 1.0, manufactured by Rhodia)
-Specific modified IR1: Specific modified IR1 synthesized as described above
-Specific modified IR2: Specific modified IR2 synthesized as described above
-Specific modified BR1: Specific modified BR1 synthesized as described above
-Specific modified BR2: Specific modified BR2 synthesized as described above
-Anti-aging agent 1: SANTOFLEX 6PPD (manufactured by Soltia Europe)
-Anti-aging agent 2: VULKANOX HS / LG (manufactured by LANXESS)
・ Wax: Paraffin wax (manufactured by Ouchi Shinko Kagaku Co., Ltd.)
-Vulcanization activator 1: YR stearate (manufactured by BF Goodrich)
・ Vulcanization activator 2: Zinc oxide No. 3 (manufactured by Shodo Chemical Co., Ltd.)
-Silane coupling agent: Si69 manufactured by Evonik Degussa
・ Vulcanization accelerator 1: Noxeller CZ-G (manufactured by Ouchi Shinko Kagaku Kogyo Co., Ltd.)
・ Vulcanization accelerator 2: Soxinol DG: (manufactured by Sumitomo Chemical Co., Ltd.)
・ Sulfur: Oil-treated sulfur (manufactured by Karuizawa Smelter)

As can be seen from Tables 1 to 6, in each table (contrast between modes having the same total content of modified IR and modified BR), comparison with a comparative example using only one of modified IR and modified BR. Therefore, the example in which the modified IR and the modified BR were used in combination showed excellent dispersibility.
From the comparison of Examples B2 to B4 and the comparison of Examples B5 to B7, Examples B3 to B4 and Examples B6 to B7 in which the modified IR / modified BR was 200% by mass or less were more excellent. It showed dispersibility.
From the comparison between Examples B1 and B3 and Example B6 (contrast between modes in which modified IR / modified BR is 100% by mass), the total content of modified IR and modified BR is 100 parts by mass of the rubber component. Examples B3 and B6 having 4 parts by mass or more showed better dispersibility. Among them, Example B6 in which the total content of the modified IR and the modified BR was 7 parts by mass or more with respect to 100 parts by mass of the rubber component showed further excellent dispersibility.

1 bead part 2 sidewall part 3 tire tread part 4 carcass layer 5 bead core 6 bead filler 7 belt layer 8 rim cushion

Claims (7)

A rubber composition containing a rubber component having a weight average molecular weight of 150,000 or more, a reinforcing filler containing at least one selected from the group consisting of carbon black and silica, a modified isoprene polymer, and a modified butadiene polymer. .. The modified isoprene polymer has an alkoxysilyl group or a functional group containing a nitrogen atom and an alkoxysilyl group at the terminal or side chain, and has a weight average molecular weight of 1,000 or more and less than 1.5 million. And
The modified butadiene polymer has an alkoxysilyl group or a functional group containing a nitrogen atom and an alkoxysilyl group at the terminal or side chain, and has a weight average molecular weight of 1,000 or more and less than 1.5 million. The rubber composition according to claim 1, which is a polymer. The content of the modified isoprene polymer is 1 to 50 parts by mass with respect to 100 parts by mass of the rubber component.
The rubber composition according to claim 1 or 2, wherein the content of the modified butadiene polymer is 1 to 50 parts by mass with respect to 100 parts by mass of the rubber component. The rubber composition according to any one of claims 1 to 3, wherein the content of the reinforcing filler is 5 to 150 parts by mass with respect to 100 parts by mass of the rubber component. The rubber composition according to any one of claims 1 to 4, wherein the reinforcing filler is at least one selected from the group consisting of carbon black and silica. In addition, it contains a silane coupling agent,
The reinforcing filler contains at least silica and
The rubber composition according to any one of claims 1 to 5, wherein the content of the silane coupling agent is 1 to 20% by mass with respect to the content of the silica. A tire manufactured by using the rubber composition according to any one of claims 1 to 6.

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