JP7343775B2 - Rubber compositions and tires - Google Patents

Description

TECHNICAL FIELD The present invention relates to a rubber composition and a tire.

Generally, reinforcing fillers such as carbon black and silica are blended into rubber compositions used for tires and the like. On the other hand, due to interactions between reinforcing fillers, the reinforcing fillers may aggregate in the rubber composition, making it impossible to obtain sufficient properties.

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

Japanese Patent Application Publication No. 2018-188598

Recently, as the performance requirements for rubber materials have increased, the dispersibility of the reinforcing filler after vulcanization (hereinafter referred to as "the dispersibility of the reinforcing filler after vulcanization") is important for rubber compositions containing reinforcing fillers. There is a need for further improvement in the "dispersibility" (also simply referred to as "dispersibility of reinforcing filler" or "dispersibility").
When the present inventors investigated 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 further increase in the future.

Therefore, in view of the above-mentioned circumstances, the present invention aims to provide a rubber composition with excellent dispersibility of a reinforcing filler, and a tire manufactured using the above-mentioned rubber composition.

As a result of intensive studies on the above-mentioned problems, the present inventors discovered that the above-mentioned problems could be solved by using a modified isoprene polymer and a modified butadiene polymer in combination, leading to the present invention.
That is, the present inventors have found that the above problem can be solved by the following configuration.

(1) Contains a rubber component with a weight average molecular weight of 150,000 or more, a reinforcing filler containing at least one member 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 1,500,000. It is a modified isoprene polymer,
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 1,500,000. 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 based on 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 based on 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 based on 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) Furthermore, it contains a silane coupling agent,
The reinforcing filler contains at least silica,
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 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 with excellent dispersibility of a reinforcing filler, and a tire manufactured using the rubber composition.

1 is a schematic partial cross-sectional view of a tire representing an example of an embodiment of the tire of the present invention.

The rubber composition of the present invention and the tire of the present invention will be explained below.
In addition, in this specification, a numerical range expressed using "~" means a range that includes the numerical values written before and after "~" as a lower limit value and an upper limit value.
Moreover, 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 types of each component are used together, the content of the component refers to the total content unless otherwise specified.

[1] Rubber composition The rubber composition of the present invention (hereinafter also simply referred to as "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. This is a rubber composition containing a reinforcing filler containing at least one of the above, a modified isoprene polymer, and a modified butadiene polymer.

Each component contained in the composition of the present invention will be explained below.

[Rubber component]
As mentioned above, the composition of the present invention contains a rubber component.
The above rubber component is not particularly limited as long as it has 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 rubber because it has excellent processability and dispersibility, and also has excellent low heat build-up, elongation at break, strength at break, and abrasion resistance after vulcanization.
Hereinafter, "excellent workability and dispersibility, and also excellent low heat build-up, elongation at break, strength at break, and abrasion resistance after vulcanization" is also referred to as "excellent effects of the present invention."
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), Examples include halogenated butyl rubber (Br-IIR, Cl-IIR) and chloroprene rubber (CR). Among 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 natural rubber in the rubber component is preferably 50% by mass or more, and 70% by mass or more, because the effects of the present invention are better. is more preferable, and even more preferably 90% by mass or more. 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 mentioned 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 10,000,000, more preferably 250,000 to 2,000,000, because 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 it is preferably from 100,000 to 5,000,000, and from 120,000 to 1,000, because the effects of the present invention are better. More preferably, it is 000.

<Measurement method>
In this specification, the weight average molecular weight (Mw) and 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 mentioned 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 because the effects of the present invention are better.

〔Carbon black〕
The composition of the present invention preferably contains carbon black as a reinforcing filler because the effects of the present invention are more excellent. As for the carbon black, one type of carbon black may be used alone, or two or more types of carbon black may be used in combination.
The above carbon black is not particularly limited, and includes various grades such as SAF-HS, SAF, ISAF-HS, ISAF, ISAF-LS, IISAF-HS, HAF-HS, HAF, HAF-LS, FEF, GPF, and SRF. can be used.
The nitrogen adsorption specific surface area (N ₂ SA) of the carbon black is not particularly limited, but it is preferably 50 to 200 m ² /g, and 70 to 150 m ² /g because the effects of the present invention are better. It is more preferable.
Here, the nitrogen adsorption specific surface area (N ₂ SA) is the amount of nitrogen adsorbed on the carbon black surface according to JIS K6217-2:2001 "Part 2: How to determine specific surface area - Nitrogen adsorption method - Single point method". This is the 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 based on 100 parts by mass of the above-mentioned rubber component because the effects of the present invention are better. , more preferably 2 to 10 parts by mass.

〔silica〕
The composition of the present invention preferably contains silica as a reinforcing filler because the effects of the present invention are more excellent.
The above-mentioned 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. The above-mentioned silica may be used alone or in combination of two or more types.

The cetyltrimethylammonium bromide (CTAB) adsorption specific surface area (hereinafter, "CTAB adsorption specific surface area" is also simply referred to as "CTAB") of the above-mentioned silica is not particularly limited; 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 in accordance with JIS K6217-3:2001 "Part 3: How to determine specific surface area - CTAB adsorption method".

The nitrogen adsorption specific surface area (N ₂ SA) of the silica is not particularly limited, but it is preferably 100 to 300 m ² /g, and preferably 194 m ² /g or more, since the effects of the present invention are better. More preferred.
Here, N ₂ SA is a substitute characteristic for the surface area that silica can use for adsorption with rubber molecules, and the amount of nitrogen adsorbed on the silica surface is calculated according to JIS K6217-2:2001 "Part 2: How to determine the specific surface area - This 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 because the effects of the present invention are more excellent. .

In the composition of the present invention, the content of silica is not particularly limited, but it is preferably 10 to 150 parts by mass based on 100 parts by mass of the above-mentioned rubber component because the effects of the present invention are more excellent. 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 it should be 5 to 150 parts by mass based on 100 parts by mass of the above-mentioned rubber component because the effects of the present invention are better. The amount is preferably 30 to 100 parts by mass, and more preferably 30 to 100 parts by mass.
In addition, 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 mentioned 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 with functional groups.

[Functional group]
The functional groups possessed by the above-mentioned modified IR are not particularly limited, but amino groups, hydroxy groups, epoxy groups, alkylsilyl groups, alkoxysilyl groups, carboxyl groups, and specific functional groups described below are selected because the effects of the present invention are better. At least one functional group selected from the group consisting of: is preferred, an alkoxysilyl group (particularly a triethoxysilyl group) and a specific functional group described below are more preferred, and a specific functional group described below is still more preferred.
The modified IR may have the functional group at the end or in the side chain, but it is preferable to have the functional group at the end because the effects of the present invention are better.

[Molecular weight]

<Weight average molecular weight>
The weight average molecular weight (Mw) of the modified IR is not particularly limited, but it is preferably from 1,000 to 10,000,000, and from 20,000 to less than 150,000, because the effects of the present invention are better. More preferably, it is 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 it is preferably from 1,000 to 5,000,000, and from 10,000 to less than 150,000, because the effects of the present invention are better. More preferably, it is 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 it is preferably 2.0 or less, more preferably 1.7 or less, because the effects of the present invention are better. 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.

[Microstructure]
<1,2-structure and 3,4-structure>
In modified IR, the ratio of 1,2-structure and 3,4-structure is not particularly limited, but it is preferably 0 to 10 mol%, and 0 to 5 mol%, because the effects of the present invention are better. It is more preferable that
Here, the ratio of 1,2-structure refers to the ratio (mol %) of repeating units having 1,2-structure to the repeating units derived from isoprene. Further, the ratio of 3,4-structure refers to the ratio (mol %) of repeating units having 3,4-structure to the repeating units derived from isoprene.

<1,4-trans structure>
In modified IR, the proportion of 1,4-trans structure is not particularly limited, but it is preferably 2 to 90 mol%, more preferably 5 to 70 mol%, because the effects of the present invention are better. preferable.
Here, the ratio of 1,4-trans structure refers to the ratio (mol %) of repeating units having 1,4-trans structure to all repeating units derived from isoprene.

<1,4-cis structure>
In modified IR, the proportion of 1,4-cis structure is not particularly limited, but it is preferably 10 to 98 mol%, more preferably 30 to 98 mol%, because the effects of the present invention are better. preferable.
Here, the ratio of 1,4-cis structure refers to the ratio (mol %) of repeating units having a 1,4-cis structure to all repeating units derived from isoprene.

In addition, below, "total proportion of 1,2-structure and 3,4-structure (mol%), proportion of 1,4-trans structure (mol%), proportion 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 it is preferably -100 to -40°C, more preferably -90 to -50°C because the effects of the present invention are better. , -85 to -60°C is more preferable.
In this specification, the glass transition temperature (Tg) is measured using a differential scanning calorimeter (DSC) at a heating rate of 10° C./min, and calculated by the midpoint method.

〔viscosity〕
The viscosity of the modified IR is not particularly limited, but it is preferably over 2,000 Pa·s, more preferably 3,000 to 100,000 Pa·s, since the effects of the present invention are better.
Further, the viscosity of the isoprene polymer before modifying the modified IR is not particularly limited, but it is preferably over 800 Pa.s, and is 1,200 to 8,000 Pa.s because the effects of the present invention are better. It is more preferable.
Further, the viscosity of the modified IR is preferably 150 to 240% of the viscosity of the isoprene polymer before modification, since the effects of the present invention are more excellent. Hereinafter, the viscosity after modification relative to the viscosity before modification is also referred to as "viscosity (after modification/before modification)."
In this specification, viscosity is measured using a cone-plate viscometer according to JIS K5600-2-3. Further, the above viscosity is assumed to be measured under the condition of 40°C.

[Specific modified isoprene polymer]
The above-mentioned modified IR is an isoprene polymer (hereinafter referred to as a "specific modified isoprene polymer") having a functional group containing a nitrogen atom and a silicon atom (hereinafter also referred to as a "specific functional group") at the end because the effects of the present invention are more excellent. ” or “specific modified IR”) is preferable.

<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. Note that the specific modified IR only needs to have a specific functional group at at least one terminal of the specific modified IR.

(Preferred aspect)
The specific functional group is not particularly limited as long as it contains a nitrogen atom _and a silicon atom; ), 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) because the effects of the present invention are 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 substituents are not particularly limited as long as they are monovalent substituents, but examples include halogen atoms, hydroxy groups, nitro groups, carboxy groups, alkoxy groups, amino groups, mercapto groups, acyl groups, imido groups, phosphino groups, and phosphinyl groups. group, a silyl group, a hydrocarbon group which may have a hetero atom, and the like.
Examples of the halogen atom include fluorine atom, chlorine atom, bromine atom, and iodine atom.
Examples of the heteroatom of the hydrocarbon group which may have a heteroatom include an oxygen atom, a nitrogen atom, a sulfur atom, a phosphorus atom, and the like.
Examples of the hydrocarbon group that may have a heteroatom include an aliphatic hydrocarbon group, an aromatic hydrocarbon group, or a combination thereof.
The aliphatic hydrocarbon group may be linear, branched, or cyclic. Specific examples of the aliphatic hydrocarbon group include linear or branched alkyl groups (especially carbon atoms 1 to 30), linear or branched alkenyl groups (especially carbon atoms 2 to 30), Examples include straight-chain or branched alkynyl groups (particularly those having 2 to 30 carbon atoms).
Examples of the aromatic hydrocarbon group include aromatic hydrocarbon groups having 6 to 18 carbon atoms such as phenyl group, tolyl group, xylyl group, and naphthyl group.

In the above formula (M), R ₁ represents a hydrogen atom, an alkyl group (preferably having 1 to 10 carbon atoms), or an alkylsilyl group (preferably having 1 to 10 carbon atoms) because the effects of the present invention are better. ), an aromatic hydrocarbon group (preferably having 6 to 18 carbon atoms), and more preferably a hydrogen atom.
A plurality of R ₁ 's may be the same or different.
When the plurality of R _1s are different, the combination of the plurality of R _1s is a hydrogen atom, an alkyl group (preferably having 1 to 10 carbon atoms), or an alkylsilyl group (preferably , carbon number 1 to 10) or an aromatic hydrocarbon group (preferably carbon number 6 to 18), and a combination of a hydrogen atom and an alkylsilyl group (preferably carbon number 1 to 10) is more preferable. Preferably, a combination of a hydrogen atom and a trialkylsilyl group (preferably having 1 to 10 carbon atoms) is even more preferable.

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

As mentioned above, in the above formula (M), L represents a single bond or a divalent organic group.
Examples of divalent organic groups include aliphatic hydrocarbon groups (for example, alkylene groups, preferably having 1 to 10 carbon atoms), aromatic hydrocarbon groups (for example, arylene groups, preferably having 6 to 18 carbon atoms), -O-, -S-, -SO ₂ -, -N(R)- (R: alkyl group), -CO-, -NH-, -COO-, -CONH-, or a group combining these (e.g. , alkyleneoxy group (-C _m H _2m O-: m is a positive integer), alkyleneoxycarbonyl group, alkylenecarbonyloxy group, etc.
L is preferably an alkylene group (preferably having 1 to 10 carbon atoms) because the effects of the present invention are better.

In the above formula (M), n represents an integer of 0 to 2.
It is preferable that n is 2 because the effects of the present invention are more excellent.

In the above formula (M), m represents an integer of 1 to 3.
It is preferable that m is 1 because the effects of the present invention are more excellent.

In the above formula (M), n and m satisfy the relational expression 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 conventionally known methods can be used. The method of controlling the molecular weight and molecular weight distribution to a specific range is not particularly limited, but examples include methods of adjusting the ratio of the initiator, monomer, and terminator, reaction temperature, and rate of addition of the initiator.

The method for producing a specific modified IR is to polymerize isoprene using an organolithium compound, and then use an electrophilic agent containing a nitrogen atom and a silicon atom, because the effects of the present invention are better in the resulting composition. It is preferable to use a method in which the polymerization is terminated by stopping the polymerization (hereinafter also referred to as "method 1 of the present invention"). Hereinafter, "the effects of the present invention are better in the obtained composition" is also simply referred to as "the effects of the present invention are better".

(organolithium compound)
The above-mentioned organic lithium compounds are not particularly limited, but specific examples thereof include monoorganolithium 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 include polyfunctional organolithium compounds such as triethylbenzene. Among these, monoorganolithium compounds such as n-butyllithium, sec-butyllithium, and tert-butyllithium are preferred because the effects of the present invention are more excellent.

Although the amount of the organolithium compound used is not particularly limited, it is preferably 0.001 to 10 mol % based on isoprene because the effects of the present invention are better.

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

(Specific electrophile)
In Method 1 of the present invention, polymerization of isoprene is stopped using an electrophile containing a nitrogen atom and a silicon atom (hereinafter also referred to as "specific electrophile"). By terminating the polymerization using a specific electrophilic agent, an isoprene polymer (specifically modified IR) having the above-mentioned specific functional group at the end can be obtained.
The specific electrophile is not particularly limited as long as it is a compound containing a _nitrogen atom and a silicon atom; ), and preferably contains a silicon atom as a hydrocarbyloxysilyl group (≡SiOR: R is a hydrocarbon group).

The specific electrophilic agent is preferably a silazane, more preferably a cyclic silazane, because the effects of the present invention are more excellent. Here, silazane refers to a compound having a structure in which a silicon atom and a nitrogen atom are directly bonded (a compound having an Si--N bond).

The above-mentioned cyclic silazane is preferably a compound represented by the following formula (S) because the effects of the present invention are more excellent.

In the above formula (S), R ₁ to R ₃ each independently represent a hydrogen atom or a substituent. Specific examples and preferred embodiments of the substituent are the same as R ₁ and R ₂ in formula (M) above.
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 formula (M) above.

In the above formula (S), R ₁ represents an alkyl group (preferably having 1 to 10 carbon atoms), an alkylsilyl group (preferably having 1 to 10 carbon atoms), an aromatic It is preferably a group hydrocarbon group (preferably having 6 to 18 carbon atoms), and more preferably an alkylsilyl group.

In the above formula (S), R ₂ and R ₃ are each independently preferably a hydrocarbyloxy group (-OR group: R is a hydrocarbon group), and alkoxy A group (preferably having 1 to 10 carbon atoms) is more preferable.

In the above formula (S), L is preferably an alkylene group (preferably having 1 to 10 carbon atoms, more preferably 2 to 8 carbon atoms, and still more preferably 3 to 5 carbon atoms) because the effects of the present invention are better. preferable.

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

The amount of the specific electrophile relative to the organolithium compound is not particularly limited, but the molar ratio is preferably 0.1 to 10, more preferably 1 to 7, because the effects of the present invention are better. preferable.

〔Content〕
In the composition of the present invention, the content of modified IR is preferably 0.1 to 50 parts by mass, and 1 to 10 parts by mass, based on 100 parts by mass of the rubber component, because the effects of the present invention are better. More preferably, it is parts by mass.

[Modified butadiene polymer]
As mentioned 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 possessed by the above-mentioned modified BR are the same as those for the above-mentioned modified IR.
The modified BR may have the functional group at the end or in the side chain, but it is preferable to have the functional group at the end because the effects of the present invention are better.

[Molecular weight]

<Weight average molecular weight>
The weight average molecular weight (Mw) of the modified BR is not particularly limited, but it is preferably from 1,000 to 10,000,000, and from 2,000 to less than 150,000, because the effects of the present invention are better. It is more preferably 5,000 to 100,000, 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 it is preferably from 1,000 to 5,000,000, and from 2,000 to less than 150,000, because the effects of the present invention are better. It is more preferably 5,000 to 100,000, 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 it is preferably 2.0 or less, more preferably 1.7 or less, because the effects of the present invention are better. 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.

[Microstructure]
<Vinyl structure>
In the modified BR, the proportion of vinyl structure (vinyl unit content) is not particularly limited, but it is preferably 10 to 50 mol%, and 20 to 40 mol%, because the effects of the present invention are better. is more preferable.
Here, the ratio of vinyl structure refers to the ratio (mol %) of repeating units having a vinyl structure to the repeating units derived from butadiene.

<1,4-trans structure>
In the modified BR, the proportion of 1,4-trans structure is not particularly limited, but it is preferably 10 to 70 mol%, more preferably 30 to 50 mol%, because the effects of the present invention are better. preferable.
Here, the ratio of 1,4-trans structure refers to the ratio (mol %) of repeating units having 1,4-trans structure to all repeating units derived from butadiene.

<1,4-cis structure>
In the modified BR, the proportion of 1,4-cis structure is not particularly limited, but it is preferably 10 to 50 mol%, more preferably 20 to 40 mol%, because the effects of the present invention are better. preferable.
Here, the ratio of 1,4-cis structure refers to the ratio (mol%) of repeating units having a 1,4-cis structure to all repeating units derived from butadiene.

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

〔viscosity〕
The viscosity of the modified BR is not particularly limited, but it is preferably 1,000 to 10,000 mPa·s, more preferably 3,000 to 6,000 mPa·s, since the effects of the present invention are better. preferable.
Further, the viscosity of the butadiene polymer before modifying the modified BR is not particularly limited, but it is preferably 500 to 5,000 mPa·s, and 1,500 to 3,000 mPa·s because the effects of the present invention are better. - It is more preferable that it is s.
Further, the viscosity of the modified BR is preferably 150 to 240% of the viscosity of the butadiene polymer before modification, since the effects of the present invention are better.
Note that the viscosity was measured using a cone-plate viscometer according to JIS K5600-2-3.

[Specific modified butadiene polymer]
The above-mentioned modified BR is a butadiene polymer (hereinafter referred to as "specific modified 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 because the effects of the present invention are more excellent. ” or “specific modified BR”) is preferable.

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

<Manufacturing method>
The method for producing the specific modified BR is not particularly limited, and conventionally known methods can be used. The method of controlling the molecular weight and molecular weight distribution to a specific range is not particularly limited, but examples include methods of adjusting the ratio of the initiator, monomer, and terminator, reaction temperature, and rate of addition of the initiator.

The method for producing a specific modified BR is to polymerize butadiene using an organolithium compound, and then use an electrophilic agent containing a nitrogen atom and a silicon atom, because the effects of the present invention are better in the resulting composition. It is preferable to use a method in which the polymerization is terminated by stopping the polymerization (hereinafter also referred to as "Method 2 of the present invention"). Hereinafter, "the effects of the present invention are better in the obtained composition" is also simply referred to as "the effects of the present invention are better".

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

(Polymerization of butadiene)
The method of polymerizing butadiene using an organolithium compound is not particularly limited, but the above-mentioned organolithium compound is added to an organic solvent solution containing butadiene, and the polymerization is carried out in a temperature range of 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 electrophilic agent are the same as those for the specific modified IR described above.

The preferable aspect of the amount of the specific electrophile relative to the organolithium compound is the same as the above-mentioned specific modified IR.

〔Content〕
In the composition of the present invention, the content of modified BR is preferably 0.1 to 50 parts by mass, and 1 to 10 parts by mass, based on 100 parts by mass of the rubber component, because the effects of the present invention are better. More preferably, it is parts 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 based on 100 parts by mass of the above-mentioned rubber component, because the effects of the present invention are more excellent. The amount is preferably 2 to 20 parts by weight, more preferably 4 to 10 parts by weight.

In the composition of the present invention, the total content of the above-mentioned modified IR and the above-mentioned modified BR is higher than the content of the above-mentioned reinforcing filler (especially silica) because the effects of the present invention are more excellent. , preferably from 1 to 50% by mass, more preferably from 3 to 40% by mass, even more preferably from 5 to 35% by mass, particularly preferably from 7 to 30% by mass, and from 10 to 30% by mass. Particularly preferred is 25% by weight, most preferably 15-20% by weight.

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

[Optional ingredients]
The composition of the present invention can contain components (optional components) other than the components mentioned above, if necessary.
Such components include, for example, silane coupling agents, terpene resins (preferably aromatic modified terpene resins), thermally expandable microcapsules, zinc oxide (zinc white), stearic acid, anti-aging agents, waxes, processed Examples include various additives commonly used in rubber compositions such as auxiliaries, process oils, liquid polymers, thermosetting resins, vulcanizing agents (e.g. sulfur), vulcanization accelerators, and vulcanization activators. It will be done.

〔Silane coupling agent〕
The composition of the present invention preferably contains a silane coupling agent because the effects of the present invention are more excellent. Particularly, when the above-mentioned reinforcing filler contains at least silica, the effects of the present invention are better, so it is preferable that the composition of the present invention contains a silane coupling agent.

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 above-mentioned hydrolyzable group is not particularly limited, and examples thereof include an alkoxy group, a phenoxy group, a carboxyl group, an alkenyloxy group, and the like. Among these, an alkoxy group is preferable because the effects of the present invention are more excellent. When the hydrolyzable group is an alkoxy group, the number of carbon atoms in the alkoxy group is preferably 1 to 16, more preferably 1 to 4, because the effects of the present invention are better. Examples of the alkoxy group having 1 to 4 carbon atoms include methoxy group, ethoxy group, and propoxy group.

The above-mentioned organic functional group is not particularly limited, but is preferably a group that can form a chemical bond with an organic compound, such as an epoxy group, a vinyl group, an acryloyl group, a methacryloyl group, an amino group, a sulfide group, a mercapto group, and a block Examples include mercapto groups (protected mercapto groups) (e.g., octanoylthio groups), among others, sulfide groups (particularly disulfide groups, tetrasulfide groups), mercapto groups, and block mercapto groups because the effects of the present invention are better. Groups are preferred.
One type of silane coupling agent may be used alone, or two or more types may be used in combination.

The above-mentioned 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 silane coupling agent include bis(3-triethoxysilylpropyl)tetrasulfide, bis(3-trimethoxysilylpropyl)tetrasulfide, bis(3-triethoxysilylpropyl)disulfide, mercaptopropyltrimethoxy Silane, mercaptopropyltriethoxysilane, 3-trimethoxysilylpropyl-N,N-dimethylthiocarbamoyl-tetrasulfide, trimethoxysilylpropyl-mercaptobenzothiazole tetrasulfide, triethoxysilylpropyl-methacrylate-monosulfide, dimethoxymethylsilyl Examples include propyl-N,N-dimethylthiocarbamoyl-tetrasulfide, 3-octanoylthio-1-propyltriethoxysilane, etc., and one type of these may be used alone or two or more types 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 it should be 1 to 20 parts by mass based on 100 parts by mass of the above-mentioned rubber component because the effects of the present invention are better. The amount is preferably 2 to 10 parts by mass, and 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, because the effects of the present invention are more excellent. More preferably, it is 15% by mass.

[2] Tire The tire of the present invention is a tire manufactured 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 air, an inert gas such as nitrogen, and other gases. Further, the tire of the present invention is preferably a tire including a tire tread portion manufactured using the composition of the present invention.
FIG. 1 shows a partial cross-sectional schematic diagram of a tire representing an example of an embodiment of the tire of the present invention, but the tire of the present invention is not limited to the embodiment shown in FIG. 1.

In FIG. 1, numeral 1 represents a bead portion, numeral 2 represents a sidewall portion, and numeral 3 represents a tire tread portion.
Furthermore, a carcass layer 4 in which fiber cords are embedded is installed between the pair of left and right bead portions 1, and the ends of this carcass layer 4 extend from the inside of the tire to the outside around the bead core 5 and bead filler 6. It is folded back and rolled up.
Further, in the tire tread portion 3, a belt layer 7 is disposed outside the carcass layer 4 over one circumference of the tire.
Further, in the bead portion 1, a rim cushion 8 is arranged at a portion that contacts the rim.
Note that the tire tread portion 3 is formed from 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, in addition to normal air or air with adjusted oxygen partial pressure, inert gases such as nitrogen, argon, helium, etc. can be used.

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

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

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

As a result, 95% of isoprene polymer (specific 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 was Obtained in yield. In addition, it was estimated by IR analysis that 1,2- and 3,4-/trans/cis=7/0/93. Further, Tg was -61°C.

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

<Specific modified BR1 (50k)>
n-BuLi (manufactured by Kanto Kagaku: 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 ( The mixture was added to a mixed solution of cyclohexane (4.2 kg, manufactured by Tokyo Kasei Co., Ltd., 0.1 mL) and stirred at room temperature for 6 hours. After the reaction, N-trimethylsilyl-1,1-dimethoxy-2-azasilacyclopentane (60 mL, 246 mmol) was added to stop the polymerization. The resulting solution was removed and concentrated under reduced pressure. The concentrated solution was poured into methanol (5.0 L) to separate methanol-insoluble components. 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 was Obtained in yield. In addition, it was estimated by IR analysis that vinyl/trans/cis=24/40/36. Further, Tg was -84°C.

<Specific modified BR2 (10k)>
n-BuLi (Kanto Kagaku: 1.60 mol/L (hexane solution), 120 mL, 192 mmol) was added to 1,3-butadiene (832 g, 15.4 mol) and 2,2-di(2-tetrahydrofuryl)propane ( The mixture was added to a mixed solution of cyclohexane (4.0 kg, manufactured by Tokyo Kasei Co., Ltd., 0.1 mL) and stirred at room temperature for 6 hours. After the reaction, N-trimethylsilyl-1,1-dimethoxy-2-azasilacyclopentane (240 mL, 984 mmol) was added to stop the polymerization. The resulting solution was removed and concentrated under reduced pressure. The concentrated solution was poured into methanol (5.0 L) to separate methanol-insoluble components. As a result, 91% of the butadiene polymer (specific 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 was Obtained in yield. In addition, it was estimated by IR analysis that vinyl/trans/cis=28/41/31. Further, 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, the components shown in Tables 1 to 6 below, excluding sulfur, vulcanization activator, and vulcanization accelerator, were mixed for 5 minutes in a Banbury mixer at 80°C. Next, sulfur, a vulcanization activator, and a vulcanization accelerator were mixed using a roll to obtain a rubber composition.

[Pain effect (after vulcanization)]
Each of the obtained rubber compositions (unvulcanized) was press-vulcanized in a mold (15 cm x 15 cm x 0.2 cm) at 160°C for 15 minutes to produce a vulcanized rubber sheet.
The produced vulcanized rubber sheet was then measured using a strain shear stress measuring machine (RPA2000, manufactured by α-Technology) to determine the strain shear modulus G' at a strain of 0.28% and the strain shear modulus G' at a strain of 30.0%. ' was measured, and the difference G'0.28 (MPa) - G'30.0 (MPa) was calculated as the pain effect.
The results are shown in Tables 1-6. The results were 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: Seast KH manufactured by Tokai Carbon Co., Ltd.
- Silica: Zeosil Premium 200MP (Silica, N ₂ SA = 200 m ² /g, CTAB = 200 m 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: Stearic acid YR (manufactured by BF Goodrich)
・Vulcanization activator 2: Zinc flower No. 3 (manufactured by Seido Kagakusha)
・Silane coupling agent: Evonik Degussa Si69
・Vulcanization accelerator 1: Noxela CZ-G (manufactured by Ouchi Shinko Chemical Industry Co., Ltd.)
・Vulcanization accelerator 2: Soccinol DG: (manufactured by Sumitomo Chemical Co., Ltd.)
・Sulfur: Oil treated sulfur (manufactured by Karuizawa Refinery Co., Ltd.)

As can be seen from Tables 1 to 6, in all tables (comparison of embodiments with the same total content of modified IR and modified BR), comparisons were made with comparative examples using only either modified IR or modified BR. The examples in which modified IR and modified BR were used together 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 modified IR/modified BR is 200% by mass or less, are more excellent. It showed dispersibility.
From the comparison between Example B1, Example B3, and Example B6 (comparison between embodiments in which modified IR/modified BR is 100% by mass), it is found that the total content of modified IR and modified BR is based on 100 parts by mass of the rubber component. Examples B3 and B6, in which the amount was 4 parts by mass or more, exhibited better dispersibility. Among them, Example B6, in which the total content of modified IR and modified BR was 7 parts by mass or more based on 100 parts by mass of the rubber component, showed even better dispersibility.

1 Bead portion 2 Sidewall portion 3 Tire tread portion 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 member 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 1,500,000. 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 1,500,000. 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 based on 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 based on 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 based on 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. Furthermore, it contains a silane coupling agent,
the reinforcing filler contains at least silica,
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 based on the content of the silica. A tire manufactured using the rubber composition according to any one of claims 1 to 6.