WO2018101362A1 - Rubber composition and pneumatic tire - Google Patents

Abstract

The main purpose of the present invention is to provide a rubber composition which has excellent workability and has an excellent balance of rolling resistance and wet grip performance.　The present invention solves this problem by providing a rubber composition obtained by combining 1 part by mass to 30 parts by mass of a hydrocarbon resin and 20 parts by mass to 80 parts by mass of carbon black having a specific surface area by nitrogen adsorption (N₂SA) in the range of 70 m²/g to 150 m²/g, per 100 parts by mass of a diene rubber comprising 30 parts by mass to 90 parts by mass of natural rubber and 10 parts by mass to 70 parts by mass of a styrene-butadiene copolymer rubber, the rubber composition being characterized in that the hydrocarbon resin includes aliphatic monomer units and aromatic monomer units, the content among the aromatic monomer units of monomer units that have a structure in which two or more cyclic structures are bonded together is at least 50 mass% of the aromatic monomer units, the weight average molecular weight (Mw) of the hydrocarbon resin is in the range of 700–6000, and the softening point of the hydrocarbon resin is in the range of 80°C–150°C.

Description

Rubber composition and pneumatic tire

The present invention relates to a rubber composition having excellent processability and excellent balance between rolling resistance and wet grip performance.

In recent years, automobile tires are strongly required to have low fuel consumption due to environmental problems and resource problems. On the other hand, in terms of safety, for example, improvement in wet grip properties is required. A cross-linked product of a rubber composition in which silica is added to a rubber component as a filler (hereinafter sometimes referred to simply as a “cross-linked rubber product”) constitutes a tire compared to a cross-linked product of a rubber composition in which carbon black is mixed. In this case, the rolling resistance is reduced. Therefore, a tire excellent in fuel efficiency can be obtained by constituting a tire using a crosslinked product of a rubber composition containing silica.

However, even if silica is blended with the conventional rubber component, the rubber component and silica have insufficient affinity, and due to their easy separation, the processability of the rubber composition before crosslinking is poor, Moreover, the rubber cross-linked product obtained by cross-linking this has a problem that the rolling resistance is insufficient when a tire is constituted.

In Patent Document 1, for the purpose of improving tire rolling resistance and wet grip properties, a specific amount of a softening agent having a specific structure and a specific amount of a hydrocarbon resin are added to a rubber component. Is disclosed.

JP 2010-241965 A

In the softener and hydrocarbon resin having a specific structure described in Patent Document 1, when a tire is manufactured from a rubber cross-linked product obtained by adding these, it certainly improves both wet grip properties and rolling resistance characteristics. However, there is a problem that it is still insufficient.

The present invention has been made in view of the above problems, and has as its main object to provide a rubber composition that is excellent in workability and excellent in the balance between rolling resistance and wet grip performance.

As a result of intensive studies on hydrocarbon resins that give rubber compositions that are excellent in workability and have a good balance between rolling resistance and wet grip performance, the present inventors have a structure in which two or more cyclic structures are combined. A hydrocarbon resin containing a monomer unit in a predetermined ratio and having a predetermined characteristic such as a weight average molecular weight within a predetermined range is improved in processability, rolling resistance and wet grip performance for a rubber composition. The present invention has been completed by finding that it is involved in a well-balanced improvement of both performances.

Thus, according to the present invention, 1 part by mass of hydrocarbon resin to 100 parts by mass of diene rubber comprising 30 parts by mass to 90 parts by mass of natural rubber and 10 parts by mass to 70 parts by mass of styrene-butadiene copolymer rubber. A rubber composition comprising 30 parts by mass and 20 parts by mass to 80 parts by mass of carbon black having a nitrogen adsorption specific surface area (N ₂ SA) in the range of 70 m ² / g to 150 m ² / g. The resin includes an aliphatic monomer unit and an aromatic monomer unit, and the aromatic unit of the monomer unit having a structure in which two or more cyclic structures are bonded among the aromatic monomer units. A rubber having a content in a body unit of 50% by mass or more, a weight average molecular weight (Mw) in a range of 700 to 6000, and a softening point in a range of 80 ° C. to 150 ° C. Composition is provided

The hydrocarbon resin is composed of 10 to 60% by mass of 1,3-pentadiene monomer units, 1 to 30% by mass of alicyclic monoolefin monomer units having 4 to 6 carbon atoms, and 4 to 4 carbon atoms. 8 acyclic monoolefin monomer unit 1% by mass to 50% by mass, alicyclic diolefin monomer unit 0% by mass to 10% by mass, and the above aromatic monomer unit 0.1% by mass to 50% by weight, the number average molecular weight (Mn) is in the range of 400 to 3000, the Z average molecular weight (Mz) is in the range of 1500 to 20000, and the ratio of the weight average molecular weight to the number average molecular weight (Mw / Mn) is preferably in the range of 1.0 to 4.0, and the ratio of the Z average molecular weight to the weight average molecular weight (Mz / Mw) is preferably in the range of 1.0 to 4.0.

The monomer having a structure in which two or more cyclic structures are bonded is at least one selected from the group consisting of naphthalene compounds, fluorene compounds, biphenyl compounds, anthracene compounds, phenanthrene compounds, indene compounds, and benzothiophene compounds. It is preferable.

The hydrocarbon resin has a mixed aniline point value of 25 ° C. to 100 ° C. measured at the lowest temperature at which a mixed solution (volume ratio 2: 1: 1) of aniline, methylcyclohexane and the hydrocarbon resin exists as a uniform solution. It is preferably within the range of ° C.

Further, according to the present invention, there is provided a pneumatic tire characterized by using the above rubber composition for a tread.

The present invention has an effect that it is possible to provide a rubber composition which is excellent in workability and has a good balance between rolling resistance and wet grip performance.

The present invention relates to a rubber composition and a pneumatic tire using it as a tread. Hereinafter, the rubber composition and pneumatic tire of the present invention will be described in detail.

I. Rubber composition The rubber composition of the present invention comprises a hydrocarbon resin 1 per 100 parts by mass of a diene rubber comprising 30 parts by mass to 90 parts by mass of natural rubber and 10 parts by mass to 70 parts by mass of a styrene-butadiene copolymer rubber. A rubber composition comprising 20 parts by mass to 80 parts by mass of carbon black having a mass part to 30 parts by mass and a nitrogen adsorption specific surface area (N ₂ SA) in the range of 70 m ² / g to 150 m ² / g, The hydrocarbon resin includes an aliphatic monomer unit and an aromatic monomer unit, and the aromatic unit is a monomer unit having a structure in which two or more cyclic structures are bonded among the aromatic monomer units. The content in the group monomer unit is 50 mass% or more, the weight average molecular weight (Mw) is in the range of 700 to 6000, and the softening point is in the range of 80 ° C. to 150 ° C. It is what.

According to the present invention, the rubber composition includes an aliphatic monomer unit and an aromatic monomer unit, and has a structure in which two or more cyclic structures are bonded among the aromatic monomer units. Excellent processability by including a predetermined amount of hydrocarbon resin containing body units in a predetermined ratio and having characteristics such as a predetermined weight average molecular weight and a softening point together with a predetermined carbon black with respect to a diene rubber. And the rubber composition excellent in the balance of rolling resistance and wet grip performance can be obtained.

Here, by using the above hydrocarbon resin, it is not clear why a rubber composition having excellent workability and excellent balance of rolling resistance and wet grip performance can be obtained, but as follows. Inferred. That is, by using a hydrocarbon resin containing a predetermined proportion of monomer units having a structure in which two or more cyclic structures are combined as an aromatic monomer unit, and having the predetermined characteristics The hydrocarbon resin can have a weight average molecular weight (Mw) that is moderately low and a softening point that is moderately high. For this reason, the hydrocarbon resin has excellent compatibility with the diene rubber, and for example, uniform mixing with the diene rubber is facilitated, so that the obtained rubber composition has excellent processability. In addition, with respect to the obtained rubber composition, the loss factor tan δ at 60 ° C. of the crosslinked product can be lowered, and the loss coefficient tan δ at 0 ° C. can be appropriately increased. As a result, for example, when a pneumatic tire using such a rubber composition as a tread is manufactured, a pneumatic tire or the like having an excellent balance of rolling resistance and wet grip performance can be formed.

From the above, by containing a predetermined amount of the hydrocarbon resin together with a predetermined carbon black with respect to the diene rubber, a rubber composition having excellent workability and excellent balance between rolling resistance and wet grip performance is obtained. It can be done.

Further, the rubber composition contains a predetermined amount of carbon black having a predetermined nitrogen adsorption specific surface area (N ₂ SA), so that the rubber composition has an excellent balance of dispersibility in the rubber composition, and a balance between rolling resistance and wet grip performance. An excellent rubber composition can be obtained. On the other hand, when carbon black in the predetermined range is used, workability deteriorates. Therefore, the rubber composition contains a predetermined amount of the hydrocarbon resin together with the carbon black, thereby suppressing a decrease in processability and improving the balance between rolling resistance and wet grip performance.

For this reason as well, the rubber composition contains a predetermined amount of the hydrocarbon resin together with a predetermined carbon black with respect to the diene rubber, so that the processability is excellent and the balance between rolling resistance and wet grip performance is achieved. It will be excellent.

The rubber composition of the present invention contains a diene rubber, a hydrocarbon resin, and carbon black. Hereinafter, each component contained in the rubber composition of the present invention will be described in detail.

A. Hydrocarbon Resin The hydrocarbon resin includes an aliphatic monomer unit and an aromatic monomer unit.

1. Aromatic monomer unit The aromatic monomer unit in the present invention includes a monomer unit having a structure in which two or more cyclic structures are bonded.

The monomer constituting the monomer unit having a structure in which two or more cyclic structures are bonded is usually one or more aliphatic carbon-carbon unsaturated bonds in the molecular structure and two or more cyclic structures. Those having a structure in which are bonded to each other are preferably used. Here, as a structure in which two or more cyclic structures are bonded, any structure that includes one or more aromatic rings among the two or more cyclic structures may be used. It may contain a ring and a non-aromatic ring structure.

The aliphatic carbon-carbon unsaturated bond is not particularly limited as long as it has radical polymerizability, and a vinyl group can be preferably used.

The aliphatic carbon-carbon unsaturated bond may be included as a part of the cyclic structure, such as a vinylene group included in a five-membered ring of indene, or a vinyl group included in 1-vinylnaphthalene. In this way, it may be bonded to the ring structure. In the present invention, it is particularly preferable that the aliphatic carbon-carbon unsaturated bond is included as a part of the cyclic structure. This is because the polymerizability, the molecular weight, and the controllability of the softening point are excellent. When an aliphatic carbon-carbon unsaturated bond is included as part of the cyclic structure, the cyclic structure is a non-aromatic ring structure.

In the case where the aliphatic carbon-carbon unsaturated bond is included as a part of the cyclic structure, the number of carbons of the cyclic structure including the aliphatic carbon-carbon unsaturated bond as a part thereof has desired characteristics. Any hydrocarbon resin can be used as long as it can be formed. For example, it can be in the range of 4 to 8, but is preferably in the range of 4 to 6.

When the monomer having a structure in which two or more cyclic structures are bonded is indene, the aliphatic carbon-carbon unsaturated bond is included as a part of the indene five-membered ring as described above, and The cyclic structure containing a group carbon-carbon unsaturated bond as a part thereof has 5 carbon atoms.

When the aliphatic carbon-carbon unsaturated bond is bonded to a cyclic structure, the aliphatic carbon-carbon unsaturated bond is bonded to the cyclic structure like a vinyl group contained in 1-vinylnaphthalene. May be bonded directly to each other, or may be bonded to the above cyclic structure via a spacer, such as an allyl group contained in allylnaphthalene.

Examples of the spacer include a hydrocarbon group bonded to a vinyl group such as a 2-propenyl group (allyl group) and 1-butenyl group, a carbonyl group bonded to a vinyl group such as an acryloyl group and a methacryloyl group. it can.

The number of carbon atoms of the spacer is not particularly limited as long as it can form a hydrocarbon resin having desired characteristics, and can be within a range of, for example, 1 to 3.

The number of the aliphatic carbon-carbon unsaturated bond contained in the monomer having a structure in which two or more cyclic structures are bonded is usually one or more, for example, within the range of 1 to 2. Although it is possible, one is preferred. Note that the number of the aliphatic carbon-carbon unsaturated bonds is the number of each monomer when two or more types of monomers are included as monomers having a structure in which two or more cyclic structures are combined. It refers to the number of aliphatic carbon-carbon unsaturated bonds involved.

In addition, a structure in which two or more cyclic structures are bonded includes a structure in which a cyclic structure forms a condensed ring group such as a naphthalene structure, a fluorene structure, an anthracene structure, a phenanthrene structure, a benzothiophene structure, an indene, or the like, a biphenyl structure A group in which the cyclic structures are directly connected by a single bond, such as a terphenyl structure, or a group in which the cyclic structures form a condensed ring group and a group in which the cyclic structures are directly connected by a single bond The thing containing both of things can be mentioned.

Examples of the structure in which two or more cyclic structures are bonded include only an aromatic ring include naphthalene structure, biphenyl structure, anthracene structure, phenanthrene structure, benzothiophene structure, and the like. Examples of those containing a family ring structure include a fluorene structure and an indene structure.

In the present invention, it is particularly preferable that the structure in which two or more cyclic structures are combined includes an aromatic ring and a non-aromatic ring structure. Since the structure in which two or more cyclic structures are combined includes an aromatic ring and a non-aromatic ring structure as a cyclic structure, the hydrocarbon resin is excellent in workability and has rolling resistance and wet grip performance. This is because a rubber composition having an excellent balance can be provided.

The cyclic structure includes oxygen, nitrogen, sulfur, such as a benzothiophene structure, in addition to a ring structure formed only by carbon, such as a naphthalene structure, a fluorene structure, a biphenyl structure, an anthracene structure, a phenanthrene structure, and the like. It may have a heterocyclic ring containing atoms other than carbon such as.

In addition, the cyclic structure may have a substituent. Examples of substituents include halogen atoms (F, Cl, Br, I), hydroxyl groups, carboxyl groups, cyano groups, amino groups, nitro groups, sulfo groups, carbamoyl groups, sulfamoyl groups, ureido groups, alkyl groups, alkenyls. Group, alkynyl group, aliphatic acyl group, aliphatic acyloxy group, alkoxy group, alkoxycarbonyl group, alkoxycarbonylamino group, alkylthio group, alkylsulfonyl group, aliphatic amide group, aliphatic sulfonamido group, aliphatic substituted amino group As typical examples, an aliphatic substituted carbamoyl group, an aliphatic substituted sulfamoyl group, an aliphatic substituted ureido group, and the like can be given.

The number of the cyclic structures included in the structure in which the two or more cyclic structures are combined may be two or more, and may be in the range of 2 to 6, but in the range of 2 to 3. Is preferred.

Specific examples of the monomer having a structure in which two cyclic structures are bonded include 1-vinylnaphthalene, 4-vinylbiphenyl, and indene. Specific examples of the monomer having a structure in which three cyclic structures are bonded include 2,7-divinylfluorene and 9-vinylanthracene.

In the present invention, the monomer having a structure in which two or more cyclic structures are bonded is preferably a naphthalene compound, a fluorene compound, a biphenyl compound, an anthracene compound, a phenanthrene compound, an indene compound and a benzothiophene compound. However, an indene compound is preferable, and indene is particularly preferable. When the monomer having a structure in which two or more cyclic structures are bonded is the above-mentioned compound, the hydrocarbon resin has excellent workability and a rubber composition having excellent balance of rolling resistance and wet grip performance. Because they can give things.

Examples of the naphthalene compound include those having a naphthalene structure and one or more aliphatic carbon-carbon unsaturated bonds in the molecular structure, such as 1-vinylnaphthalene, 2-vinylnaphthalene, allylnaphthalene, butenyl. Naphthalene etc. can be mentioned.

Examples of the fluorene compound include those having a fluorene structure and one or more aliphatic carbon-carbon unsaturated bonds in its molecular structure, such as 2,7-divinylfluorene, 2-vinylfluorene, allylfluorene, Examples include butenyl fluorene.

Examples of the biphenyl compound include those having a biphenyl structure and one or more aliphatic carbon-carbon unsaturated bonds in the molecular structure, such as 4-vinylbiphenyl, 4-vinyl-p-terphenyl, etc. Can be mentioned.

Examples of the anthracene compounds include those having an anthracene structure and one or more aliphatic carbon-carbon unsaturated bonds in the molecular structure, such as 9-vinylanthracene, 2-vinylanthracene, 9,10-divinyl. Anthracene, allyl anthracene, butenyl anthracene, etc. can be mentioned.

Examples of the phenanthrene compound include those having a phenanthrene structure and one or more aliphatic carbon-carbon unsaturated bonds in the molecular structure, such as 9-vinylphenanthrene and 3-vinylphenanthrene. .

The indene compound may be any compound having an indene structure in its molecular structure. For example, indene, methylindene, ethylindene, propylindene, butylindene, t-butylindene, sec-butylindene, n-pentyl Examples include alkyl-substituted indenes such as indene, 2-methyl-butylindene, 3-methyl-butylindene, n-hexylindene, 2-methyl-pentylindene, 3-methyl-pentylindene, 4-methyl-pentylindene, etc. Can do.

Examples of the benzothiophene compound include those having a benzothiophene structure and one or more aliphatic carbon-carbon unsaturated bonds in the molecular structure. For example, 5-vinylbenzothiophene, 2-vinyldibenzothiophene, etc. Can be mentioned.

The monomer having a structure in which two or more cyclic structures are bonded may include only one type of monomer, or may include two or more types of monomers mixed together. Good. For example, the monomer having a structure in which two or more cyclic structures are bonded can be a mixture of 9-vinylanthracene which is an anthracene compound and 9-vinylphenanthrene which is a phenanthrene compound.

The content of the monomer unit having a structure in which two or more cyclic structures are combined in the aromatic monomer unit may be 50% by mass or more, and is in the range of 55% by mass to 99.9% by mass. In particular, it is preferably in the range of 58% by mass to 99.85% by mass, and particularly preferably in the range of 60% by mass to 99.8% by mass. It is because the said hydrocarbon resin can give the rubber composition excellent in workability and the balance of rolling resistance and wet grip performance because the said content is in the above-mentioned range.

The aromatic monomer unit in the present invention includes a monomer unit having a structure in which two or more cyclic structures are bonded, but in addition to a monomer unit having a structure in which two or more cyclic structures are bonded, A monomer unit containing only one cyclic structure, that is, a monomer unit containing only one aromatic ring as the cyclic structure may be included.

Examples of the monomer constituting the monomer unit containing only one cyclic structure include styrene, α-methylstyrene, vinyltoluene and the like.

As the content of the aromatic monomer unit in the hydrocarbon resin, the hydrocarbon resin can provide a rubber composition having excellent workability and excellent balance between rolling resistance and wet grip performance. For example, it may be in the range of 0.1% by mass to 50% by mass, preferably in the range of 5% by mass to 45% by mass, and more preferably in the range of 8% by mass to 43% by mass. It is preferably within the range of 10% by mass to 40% by mass. It is because the said hydrocarbon resin can give the rubber composition excellent in workability and the balance of rolling resistance and wet grip performance because the said content is in the above-mentioned range.

2. Aliphatic monomer unit As the aliphatic monomer unit in the present invention, it is possible to provide a rubber composition that exhibits the above-mentioned predetermined characteristics, is excellent in workability, and has an excellent balance of rolling resistance and wet grip performance. Any hydrocarbon resin can be used as long as it can be formed.

Such an aliphatic monomer unit may be any unit that does not contain an aromatic ring, such as a 1,3-pentadiene monomer unit, an alicyclic monoolefin monomer having 4 to 6 carbon atoms. A unit, an acyclic monoolefin monomer unit having 4 to 8 carbon atoms, an alicyclic diolefin monomer unit, and the like can be preferably included. For example, as an aliphatic monomer unit, in a hydrocarbon resin, 1,3-pentadiene monomer unit 10 mass% to 60 mass%, C 4-6 alicyclic monoolefin monomer unit 1 mass % To 30% by mass, 1 to 50% by mass of acyclic monoolefin monomer units having 4 to 8 carbon atoms, and 0 to 10% by mass of alicyclic diolefin monomer units. it can.

The content of 1,3-pentadiene monomer units in the hydrocarbon resin is a hydrocarbon resin that is excellent in processability and can provide a rubber composition with a good balance of rolling resistance and wet grip performance. Any material can be used as long as it can be obtained. For example, it can be in the range of 10% by mass to 60% by mass, preferably in the range of 15% by mass to 55% by mass, and more preferably 20% by mass to It is preferably in the range of 50% by mass, and particularly preferably in the range of 25% by mass to 48% by mass. It is because the said hydrocarbon resin can give the rubber composition excellent in workability and the balance of rolling resistance and wet grip performance because the said content is in the above-mentioned range.

The cis / trans isomer ratio in 1,3-pentadiene is not particularly limited and may be any ratio.

The alicyclic monoolefin having 4 to 6 carbon atoms is a hydrocarbon compound having 4 to 6 carbon atoms having one aliphatic carbon-carbon unsaturated bond and a non-aromatic ring structure in its molecular structure. is there. Specific examples of the alicyclic monoolefin having 4 to 6 carbon atoms include cyclobutene, cyclopentene, cyclohexene, methylcyclobutene, and methylcyclopentene.

The content of the alicyclic monoolefin monomer unit having 4 to 6 carbon atoms in the hydrocarbon resin is to provide a rubber composition having excellent workability and a good balance between rolling resistance and wet grip performance. Any hydrocarbon resin can be used as long as it can be obtained. For example, it can be in the range of 1% by mass to 30% by mass, and preferably in the range of 3% by mass to 28% by mass. In particular, it is preferably in the range of 5% by mass to 26% by mass, and particularly preferably in the range of 7% by mass to 25% by mass. It is because the said hydrocarbon resin can give the rubber composition excellent in workability and the balance of rolling resistance and wet grip performance because the said content is in the above-mentioned range.

In the alicyclic monoolefin having 4 to 6 carbon atoms, the ratio of each of the corresponding compounds may be any ratio, and is not particularly limited, but preferably contains at least cyclopentene, and has 4 to 6 carbon atoms. The proportion of cyclopentene in the alicyclic monoolefin is more preferably 50% by mass or more.

An acyclic monoolefin having 4 to 8 carbon atoms has one aliphatic carbon-carbon unsaturated bond in its molecular structure, and is a chain hydrocarbon compound having 4 to 8 carbon atoms having no ring structure It is. Specific examples of the acyclic monoolefin having 4 to 8 carbon atoms include butenes such as 1-butene, 2-butene and isobutylene (2-methylpropene); 1-pentene, 2-pentene, 2-methyl-1 -Pentenes such as butene, 3-methyl-1-butene, 2-methyl-2-butene; hexenes such as 1-hexene, 2-hexene, 2-methyl-1-pentene; 1-heptene, 2-heptene Heptenes such as 2-methyl-1-hexene; 1-octene, 2-octene, 2-methyl-1-heptene, diisobutylene (2,4,4-trimethyl-1-pentene and 2,4,4- Octenes such as trimethyl-1-pentene).

The content of the acyclic monoolefin monomer unit having 4 to 8 carbon atoms in the hydrocarbon resin is to provide a rubber composition having excellent workability and excellent balance between rolling resistance and wet grip performance. Any hydrocarbon resin can be used as long as it can be obtained. For example, it can be in the range of 1 to 50% by mass, preferably in the range of 5 to 45% by mass, In particular, it is preferably in the range of 10% by mass to 42% by mass, and particularly preferably in the range of 15% by mass to 40% by mass. It is because the said hydrocarbon resin can give the rubber composition excellent in workability and the balance of rolling resistance and wet grip performance because the said content is in the above-mentioned range.

In the acyclic monoolefin having 4 to 8 carbon atoms, the ratio of each of the corresponding compounds (including isomers) may be any ratio, and is not particularly limited. However, at least 2-methyl-2-butene, Preferably, at least one selected from the group consisting of isobutylene and diisobutylene is included, and the total amount of 2-methyl-2-butene, isobutylene and diisobutylene occupies in the alicyclic monoolefin having 4 to 6 carbon atoms The ratio is more preferably 50% by mass or more.

The hydrocarbon resin may contain an alicyclic diolefin as a raw material. An alicyclic diolefin is a hydrocarbon compound having two or more aliphatic carbon-carbon unsaturated bonds and a non-aromatic ring structure in its molecular structure. Specific examples of the alicyclic diolefin include multimers of cyclopentadiene such as cyclopentadiene and dicyclopentadiene, and multimers of methylcyclopentadiene and methylcyclopentadiene.

The content of the cycloaliphatic diolefin monomer unit in the hydrocarbon resin is a hydrocarbon resin that is excellent in processability and can provide a rubber composition with a good balance of rolling resistance and wet grip performance. Any material can be used as long as it can be obtained. For example, it can be in the range of 0% by mass to 10% by mass, and preferably in the range of 0% by mass to 7% by mass. It is preferably in the range of 5% by mass, and particularly preferably in the range of 0% by mass to 3% by mass. It is because the said hydrocarbon resin can give the rubber composition excellent in workability and the balance of rolling resistance and wet grip performance because the said content is in the above-mentioned range.

The above aliphatic monomer units are 1,3-pentadiene monomer units, alicyclic monoolefin monomer units having 4 to 6 carbon atoms, and acyclic monoolefin monomer units having 4 to 8 carbon atoms. In addition to the alicyclic diolefin monomer unit, within the scope of obtaining a hydrocarbon resin that provides a rubber composition having excellent workability and excellent balance of rolling resistance and wet grip performance, Monomer units may be included.

Other monomers used for constituting such other monomer units may be compounds having addition polymerizability that can be addition copolymerized with 1,3-pentadiene or the like other than the aforementioned monomers. There is no particular limitation. Examples of the other monomers include carbon numbers other than 1,3-pentadiene such as 1,3-butadiene, 1,2-butadiene, isoprene, 1,3-hexadiene, and 1,4-pentadiene. An unsaturated monoolefin having 7 or more carbon atoms such as cycloheptene; an acyclic monoolefin having 4 to 8 carbon atoms such as ethylene, propylene and nonene.

However, the content of the other monomer units in the hydrocarbon resin in the hydrocarbon resin is not particularly limited as long as the hydrocarbon resin having the predetermined characteristics can be obtained. Usually, it is in the range of 0% by mass to 30% by mass, preferably in the range of 0% by mass to 25% by mass, and more preferably in the range of 0% by mass to 20% by mass. This is because the hydrocarbon resin can provide a rubber composition having excellent processability and a good balance between rolling resistance and wet grip performance.

As the content of the aliphatic monomer unit in the hydrocarbon resin, the hydrocarbon resin can provide a rubber composition having excellent workability and excellent balance of rolling resistance and wet grip performance. For example, it can be in the range of 50% by mass to 99.9% by mass, and preferably in the range of 60% by mass to 90% by mass. It is because the said hydrocarbon resin can give the rubber composition excellent in workability and the balance of rolling resistance and wet grip performance because the said content is in the above-mentioned range.

3. Hydrocarbon Resin The weight average molecular weight (Mw) of the hydrocarbon resin is not particularly limited as long as it is in the range of 700 to 6000, but it is particularly preferable to be in the range of 900 to 5000. More preferably, it is within the range of 1000 to 4000. This is because, when the weight average molecular weight (Mw) is within the above range, the hydrocarbon resin can be excellent in compatibility with the diene rubber. As a result, the hydrocarbon resin can easily reduce the loss coefficient tan δ at 60 ° C. of the cross-linked product of the rubber composition and can be excellent in rolling resistance. In addition, when the weight average molecular weight (Mw) is within the above-described range, the hydrocarbon resin can easily increase the loss coefficient tan δ at 0 ° C. and can have excellent rolling resistance. Because.

The number average molecular weight (Mn) of the hydrocarbon resin can be in the range of 400 to 3000, preferably in the range of 450 to 2500, particularly in the range of 500 to 2000. Is more preferable. This is because when the number average molecular weight (Mn) is within the above-mentioned range, the hydrocarbon resin can be excellent in compatibility with the diene rubber. As a result, the hydrocarbon resin can easily reduce the loss coefficient tan δ at 60 ° C. of the cross-linked product of the rubber composition and can be excellent in rolling resistance.

The Z average molecular weight (Mz) of the hydrocarbon resin can be in the range of 1500 to 20000, preferably in the range of 1800 to 15000, particularly in the range of 2000 to 10,000. Is more preferable. This is because, when the Z average molecular weight (Mz) is within the above range, the hydrocarbon resin can be excellent in compatibility with the diene rubber. As a result, the hydrocarbon resin can easily reduce the loss coefficient tan δ at 60 ° C. of the cross-linked product of the rubber composition and can be excellent in rolling resistance.

In the present invention, the number average molecular weight (Mn), the weight average molecular weight (Mw), and the Z average molecular weight (Mz) of the hydrocarbon resin are determined as polystyrene-converted values measured by high performance liquid chromatography. For the measurement of number average molecular weight, weight average molecular weight and Z average molecular weight, more specifically, “HLC-8320GPC” manufactured by Tosoh Corporation is used as a measuring apparatus, and three “TSKgel SuperMultipleHZ” manufactured by Tosoh Corporation are connected. And measured with a tetrahydrofuran as a solvent at 40 ° C. and a flow rate of 1.0 mL / min.

The ratio (Mw / Mn) of the weight average molecular weight to the number average molecular weight of the hydrocarbon resin can be in the range of 1.0 to 4.0, and more preferably in the range of 1.1 to 3.5. In particular, it is more preferable to be in the range of 1.2 to 3.0. This is because when the ratio is within the above-described range, the hydrocarbon resin can be excellent in compatibility with the diene rubber. As a result, the hydrocarbon resin can easily reduce the loss coefficient tan δ at 60 ° C. of the cross-linked product of the rubber composition and can be excellent in wet grip performance.

The ratio of the Z average molecular weight to the weight average molecular weight of the hydrocarbon resin (Mz / Mw) can be in the range of 1.0 to 4.0, and in particular, in the range of 1.1 to 3.5. In particular, it is more preferable to be in the range of 1.2 to 3.0. This is because when the ratio is within the above-described range, the hydrocarbon resin can be excellent in compatibility with the diene rubber. As a result, the hydrocarbon resin can easily reduce the loss coefficient tan δ at 60 ° C. of the cross-linked product of the rubber composition and can be excellent in wet grip performance.

The softening point of the hydrocarbon resin is not particularly limited as long as it is in the range of 80 ° C. to 150 ° C. Among them, it is preferably in the range of 85 ° C. to 145 ° C., particularly 90 ° C. to More preferably, it is within the range of 140 ° C. This is because when the softening point is within the above-described range, the hydrocarbon resin can be excellent in compatibility with the diene rubber. As a result, the hydrocarbon resin can easily reduce the loss coefficient tan δ at 60 ° C. of the cross-linked product of the rubber composition and can be excellent in rolling resistance. Further, since the softening point is within the above-described range, the hydrocarbon resin can easily increase the loss coefficient tan δ at 0 ° C. and can have excellent wet grip performance. .

The softening point in the present invention is a value measured according to JIS K 6863 for hydrocarbon resins, for example.

The mixed aniline point (MMAP) of the hydrocarbon resin can be in the range of 25 ° C. to 100 ° C., preferably 27 ° C. to 90 ° C., particularly 30 ° C. to 75 ° C. It is more preferable to be within the range. This is because when the mixed aniline point is within the above range, the hydrocarbon resin can be excellent in compatibility with the diene rubber. As a result, the hydrocarbon resin can easily reduce the loss coefficient tan δ at 60 ° C. of the cross-linked product of the rubber composition and can be excellent in rolling resistance. In addition, since the mixed aniline point is within the above range, the hydrocarbon resin can easily increase the loss coefficient tan δ at 0 ° C. and can have excellent wet grip performance. is there.

The mixed aniline point in the present invention is a temperature measured as the lowest temperature at which a mixed solution (volume ratio 2: 1: 1) of aniline, methylcyclohexane and the above hydrocarbon resin exists as a uniform solution. It is a value measured using methylcyclohexane instead of heptane according to JIS K 2256 for hydrocarbon resins.

The blending amount of the hydrocarbon resin is not particularly limited as long as it is 1 to 30 parts by mass with respect to 100 parts by mass of the diene rubber. It is preferably within the range of 20 to 20 parts by mass. This is because, when the blending amount is within the above-described range, the rubber composition has excellent processability and excellent balance between rolling resistance and wet grip performance.

4). Method for Producing Hydrocarbon Resin The method for producing the hydrocarbon resin may be any method that can obtain a hydrocarbon resin containing an aliphatic monomer unit and an aromatic monomer unit. A preferred example is a method in which a polymerizable component (monomer mixture A) having monomers capable of constituting a monomer unit and an aromatic monomer unit is subjected to addition polymerization.

For example, a hydrocarbon resin can be obtained by addition polymerization using a Friedel-Crafts type cationic polymerization catalyst. As a method suitably used for producing the hydrocarbon resin, the following aluminum halide (A), halogenated hydrocarbon (B1) in which a halogen atom is bonded to a tertiary carbon atom, and carbon-carbon non-carbon are described. In combination with a halogenated hydrocarbon (B) selected from the group consisting of a halogenated hydrocarbon (B2) in which a halogen atom is bonded to a carbon atom adjacent to the saturated bond, a polymerization catalyst is obtained, and the above aliphatic monomer and The method which has the superposition | polymerization process of superposing | polymerizing the monomer mixture A containing an aromatic monomer can be mentioned.

Moreover, the addition amount of each monomer contained in the monomer mixture A can be the same as the content of each monomer unit in the hydrocarbon resin. Therefore, as the aliphatic monomer unit, 1,3-pentadiene monomer unit 10 mass% to 60 mass%, C 4-6 alicyclic monoolefin monomer unit 1 mass% to 30 mass%, It contains 1 to 50% by mass of acyclic monoolefin monomer unit having 4 to 8 carbon atoms and 0 to 10% by mass of alicyclic diolefin monomer unit, and 0% of aromatic monomer unit. More specifically, in the case of producing a hydrocarbon resin containing 1% by mass to 50% by mass, the above-described production method is more specifically composed of 10% by mass to 60% by mass of 1,3-pentadiene monomer, and 4 to 6 carbon atoms. 1% by mass to 30% by mass of alicyclic monoolefin monomer, 1% by mass to 50% by mass of acyclic monoolefin monomer having 4 to 8 carbon atoms, 0% by mass of alicyclic diolefin monomer 10% by mass, and the content of the monomer having a structure in which two or more cyclic structures are combined is Can be assumed to have a polymerization step of polymerizing the monomer mixture A comprising an aromatic monomer 0.1 wt% to 50 wt% of the above is at least 50 wt% in aromatic monomer.

Specific examples of the aluminum halide (A) include aluminum chloride (AlCl ₃ ) and aluminum bromide (AlBr ₃ ). Of these, aluminum chloride is preferably used from the viewpoint of versatility.

The amount of aluminum halide (A) used is not particularly limited, but is preferably in the range of 0.05 to 10 parts by mass, more preferably 100 parts by mass of the polymerizable component (monomer mixture A). It is within the range of 0.1 to 5 parts by mass.

By using the halogenated hydrocarbon (B) in combination with the aluminum halide (A), the activity of the polymerization catalyst becomes extremely good.

Specific examples of the halogenated hydrocarbon (B1) in which a halogen atom is bonded to a tertiary carbon atom include t-butyl chloride, t-butyl bromide, 2-chloro-2-methylbutane, and triphenylmethyl chloride. . Among these, t-butyl chloride is particularly preferably used because it has an excellent balance between activity and ease of handling.

Examples of the unsaturated bond in the halogenated hydrocarbon (B2) in which a halogen atom is bonded to a carbon atom adjacent to the carbon-carbon unsaturated bond include a carbon-carbon double bond and a carbon-carbon triple bond, and an aromatic ring It also includes a carbon-carbon conjugated double bond in Specific examples of such compounds include benzyl chloride, benzyl bromide, (1-chloroethyl) benzene, allyl chloride, 3-chloro-1-propyne, 3-chloro-1-butene, 3-chloro-1-butyne, Examples include cinnamon chloride. Among these, benzyl chloride is preferably used because it is excellent in balance between activity and ease of handling. In addition, halogenated hydrocarbon (B) may be used by 1 type, or may be used in combination of 2 or more types.

The amount of the halogenated hydrocarbon (B) used is preferably in the range of 0.05 to 50, more preferably in the range of 0.1 to 10, in terms of the molar ratio to the aluminum halide (A).

In performing the polymerization reaction, the order of adding each component of the monomer mixture and the polymerization catalyst to the polymerization reactor is not particularly limited, and may be added in any order, but the polymerization reaction is well controlled, From the viewpoint of more accurately controlling the weight average molecular weight and the like, after adding the monomer mixture and a part of the components of the polymerization catalyst to the polymerization reactor and starting the polymerization reaction, the remainder of the polymerization catalyst is subjected to the polymerization reaction It is preferable to add to the vessel.

In the production of the hydrocarbon resin, when the alicyclic monoolefin monomer unit is included as the aliphatic monomer unit, first, the aluminum halide (A) and the alicyclic monoolefin may be mixed. preferable. This is because by subjecting the aluminum halide (A) and the alicyclic monoolefin to contact treatment, gel formation can be prevented and a hydrocarbon resin in which the weight average molecular weight and the like are controlled with high accuracy can be obtained.

The amount of the alicyclic monoolefin mixed with the aluminum halide (A) is preferably at least 5 times (mass ratio) the amount of the aluminum halide (A). If the amount of the alicyclic monoolefin is too small, the effect of preventing gel formation may be insufficient. The mass ratio of alicyclic monoolefin to aluminum halide (A) is preferably 5: 1 to 120: 1, more preferably 10: 1 to 100: 1, and even more preferably 15: 1 to 80: 1. . If the alicyclic monoolefin is used in an excessive amount from this ratio, the catalytic activity is lowered and the polymerization may not proceed sufficiently.

When mixing the aluminum halide (A) and the alicyclic monoolefin, the charging order is not particularly limited, and the aluminum halide (A) may be charged into the alicyclic monoolefin, and conversely, An alicyclic monoolefin may be introduced into the aluminum halide (A). Since mixing usually involves exotherm, an appropriate diluent can also be used. As the diluent, a solvent described later can be used.

In the case where the aliphatic monomer unit includes a 1,3-pentadiene monomer unit, an acyclic monoolefin monomer unit, etc. in addition to the alicyclic monoolefin monomer unit, as described above. After preparing the mixture M of the aluminum halide (A) and the alicyclic monoolefin, it is preferable to mix the mixture M with the mixture a containing at least 1,3-pentadiene and the acyclic monoolefin. The mixture a may contain an alicyclic diolefin.

The preparation method of the mixture a is not particularly limited, and each of the pure compounds may be mixed to obtain the target mixture a. For example, a mixture containing the target monomer derived from a fraction of a naphtha decomposition product May be used to obtain the desired mixture a. For example, in order to incorporate 1,3-pentadiene or the like into the mixture a, the C5 fraction after extraction of isoprene and cyclopentadiene (including its multimer) can be preferably used.

It is preferable to further mix the halogenated hydrocarbon (B) together with the mixture a and the mixture M. There are no particular restrictions on the order of these three parties.

From the viewpoint of better controlling the polymerization reaction, it is preferable to carry out the polymerization reaction by adding a solvent to the polymerization reaction system. The type of the solvent is not particularly limited as long as it does not inhibit the polymerization reaction, but saturated aliphatic hydrocarbons or aromatic hydrocarbons are preferable. Examples of the saturated aliphatic hydrocarbon used as the solvent include n-pentane, n-hexane, 2-methylpentane, 3-methylpentane, n-heptane, 2-methylhexane, 3-methylhexane, and 3-ethylpentane. , 2,2-dimethylpentane, 2,3-dimethylpentane, 2,4-dimethylpentane, 3,3-dimethylpentane, 2,2,3-trimethylbutane, 2,2,4-trimethylpentane, etc. Examples include 5-10 chain saturated aliphatic hydrocarbons; cyclic saturated aliphatic hydrocarbons having 5 to 10 carbon atoms such as cyclopentane, cyclohexane, cycloheptane, cyclooctane and the like. Examples of the aromatic hydrocarbon used as the solvent include aromatic hydrocarbons having 6 to 10 carbon atoms such as benzene, toluene and xylene. A solvent may be used individually by 1 type and may be used as a 2 or more types of mixed solvent. The amount of the solvent used is not particularly limited, but is preferably in the range of 10 parts by weight to 1,000 parts by weight with respect to 100 parts by weight of the polymerizable component (monomer mixture A), and 50 parts by weight to More preferably, it is in the range of 500 parts by weight. For example, a mixture of an addition polymerizable component and a non-addition polymerizable component such as a mixture of cyclopentane and cyclopentene derived from the C5 fraction is added to the polymerization reaction system, and the addition polymerizable component is a single amount. It can be used as a component of the body mixture, and the non-addition polymerizable component can be used as a solvent.

The polymerization temperature for carrying out the polymerization reaction is not particularly limited, but is preferably in the range of −20 ° C. to 100 ° C., and preferably in the range of 0 ° C. to 75 ° C. If the polymerization temperature is too low, the polymerization activity may be reduced and productivity may be inferior. If the polymerization temperature is too high, the controllability such as the weight average molecular weight of the resulting hydrocarbon resin may be inferior. The pressure for performing the polymerization reaction may be atmospheric pressure or increased pressure. The polymerization reaction time can be appropriately selected, but is usually selected within the range of 10 minutes to 12 hours, preferably 30 minutes to 6 hours.

The polymerization reaction can be stopped by adding a polymerization terminator such as methanol, an aqueous sodium hydroxide solution or an aqueous ammonia solution to the polymerization reaction system when a desired polymerization conversion rate is obtained.

The method for producing the hydrocarbon resin has at least the polymerization step, but may have other steps as necessary. Examples of the other steps include, for example, a catalyst residue that is generated when a polymerization terminator is added in the polymerization step after the polymerization step to inactivate the polymerization catalyst, and the catalyst residue insoluble in the solvent is removed by filtration or the like. After the polymerization reaction is stopped by the removal step and the polymerization step, the unreacted monomer and solvent are removed, and further, the low molecular weight oligomer component is removed by steam distillation or the like, and the solid resin is obtained by cooling. Etc.

B. Diene rubber The diene rubber is composed of natural rubber and styrene-butadiene copolymer rubber. That is, the rubber composition contains 1 to 30 parts by mass of a hydrocarbon resin and 20 parts by mass of carbon black when the total amount of natural rubber and styrene-butadiene copolymer rubber is 100 parts by mass. Parts to 80 parts by mass.

As the styrene-butadiene copolymer rubber, emulsion polymerized styrene-butadiene copolymer rubber, solution polymerized styrene-butadiene copolymer rubber and the like can be used.

The natural rubber and styrene-butadiene copolymer rubber are not particularly limited in molecular weight or microstructure, and may be epoxidized even if they are end-modified with amine, amide, silyl, alkoxysilyl, carboxyl, hydroxyl groups, etc. May be. The natural rubber and styrene-butadiene copolymer rubber may be hydrogenated, but are preferably not hydrogenated.

The amount of the natural rubber is not particularly limited as long as it is in the range of 30 to 90 parts by mass in 100 parts by mass of the diene rubber, but is in the range of 35 to 85 parts by mass. In particular, it is preferably in the range of 40 to 80 parts by mass.

The amount of the styrene-butadiene copolymer rubber is not particularly limited as long as it is in the range of 10 to 70 parts by mass in 100 parts by mass of the diene rubber, but 15 to 65 parts by mass. In particular, it is preferably in the range of 20 to 60 parts by mass. This is because, when the blending amount is within the above-described range, the rubber composition has excellent processability and excellent balance between rolling resistance and wet grip performance.

C. Carbon black The carbon black is blended in the rubber composition together with the diene rubber and the hydrocarbon resin. The carbon black has a nitrogen adsorption specific surface area (N ₂ SA) in the range of 70 m ² / g to 150 m ² / g.

The nitrogen adsorption specific surface area of the carbon black is not particularly limited as long as it is within the range of 70 m ² / g to 150 m ² / g, but is within the range of 80 m ² / g to 130 m ² / g. It is preferable. This is because, when the nitrogen adsorption specific surface area is within the above range, a rubber composition having excellent workability and a good balance between rolling resistance and wet grip performance can be provided.

The nitrogen adsorption specific surface area (N ₂ SA) can be determined according to JIS K6217-2.

As the carbon black, any carbon black having the predetermined nitrogen adsorption specific surface area may be used. For example, those generally used for rubber compositions described in JP-A-2016-30795 can be used. More specifically, furnace black, acetylene black, thermal black, channel black, graphite, and the like can be used as the carbon black.

The blending amount of the carbon black is not particularly limited as long as it is in the range of 20 to 80 parts by mass with respect to 100 parts by mass of the diene rubber. The content is preferably in the range of 30 to 70 parts by mass, and particularly preferably in the range of 35 to 65 parts by mass. This is because, when the blending amount is within the above-described range, the rubber composition has excellent processability and excellent balance between rolling resistance and wet grip performance.

D. Other Components The rubber composition of the present invention contains a diene rubber, a hydrocarbon resin, and carbon black, but may contain other components as necessary. Examples of the other components include compounding agents such as a silane coupling agent, a crosslinking agent, a crosslinking accelerator, a crosslinking activator, an anti-aging agent, an activator, a process oil, a plasticizer, a lubricant, and a tackifier. Necessary amount can be blended. Such other components and their contents can be the same as those described in JP-A-2016-30795, for example.

The other components can include fillers other than carbon black having the predetermined nitrogen adsorption specific surface area. As the filler other than the predetermined carbon black, those generally used in rubber compositions can be used, for example, silica, clay, diatomaceous earth, talc, barium sulfate, calcium carbonate, magnesium carbonate, metal oxide. , Mica, aluminum hydroxide, various metal powders, wood powder, glass powder, ceramic powder, etc., and inorganic hollow fillers such as glass balloons and silica balloons; made of polystyrene, polyvinylidene fluoride, polyvinylidene fluoride copolymer, etc. An organic hollow filler etc. can be mentioned. Among these fillers, for example, silica described in JP-A-2016-30795 can be used. Moreover, the filler should just contain at least 1 type, may contain only 1 type, and may mix and use 2 or more types.

The filler content other than the predetermined carbon black is not particularly limited as long as it can provide a rubber composition that is excellent in workability and has a good balance between rolling resistance and wet grip performance. The said content is a ratio with respect to 100 mass parts of diene rubbers, for example, and is 120 mass parts or less normally.

The rubber composition may contain only the diene rubber as a rubber component, that is, only natural rubber and styrene-butadiene copolymer rubber, but the other component may be other than the diene rubber. The rubber component may be included. Examples of the other rubber components include natural rubber and styrene such as isoprene rubber (IR), butadiene rubber (BR), acrylonitrile-butadiene copolymer rubber (NBR), and ethylene-propylene-diene terpolymer (EPDM). -Diene rubbers other than butadiene copolymer rubbers.

In the present invention, the other rubber component may be blended in any amount as long as it is excellent in processability and can provide a rubber composition with a good balance of rolling resistance and wet grip performance. It can be 10 parts by mass or less with respect to 100 parts by mass of the diene rubber, and is preferably 5 parts by mass or less.

E. Rubber composition The rubber composition of the present invention may be prepared by kneading each component according to a conventional method. For example, a component excluding a thermally unstable component such as a crosslinking agent or a crosslinking accelerator and a diene rubber are used. After kneading, a heat-unstable component such as a crosslinking agent or a crosslinking accelerator can be mixed with the kneaded product to obtain a desired composition. The kneading temperature of the component excluding the thermally unstable component and the diene rubber is preferably in the range of 80 ° C. to 200 ° C., more preferably in the range of 120 ° C. to 180 ° C., and the kneading time is preferably Is 30 seconds to 30 minutes. The kneaded product and the thermally unstable component are usually mixed after cooling to 100 ° C. or lower, preferably 80 ° C. or lower.

As a crosslinking method using the rubber composition of the present invention as a rubber crosslinked product, a known crosslinking method can be used. For example, a molding machine corresponding to a desired shape, such as an extruder, an injection molding machine, a compressor, Examples of the method include forming by a roll or the like, performing a crosslinking reaction by heating, and fixing the shape as a crosslinked product. In this case, it is possible to perform crosslinking after molding in advance or at the same time as molding. The molding temperature is usually in the range of 10 ° C to 200 ° C, preferably in the range of 25 ° C to 120 ° C. The crosslinking temperature is usually in the range of 100 ° C. to 200 ° C., preferably in the range of 130 ° C. to 190 ° C., and the crosslinking time is usually in the range of 1 minute to 24 hours, preferably 2 minutes to 12 hours. And particularly preferably within the range of 3 minutes to 6 hours.

Further, depending on the shape, size, etc. of the rubber cross-linked product, even if the surface is cross-linked, it may not be sufficiently cross-linked to the inside. Good.

As the heating method, a general method used for crosslinking of the rubber composition such as press heating, steam heating, oven heating, hot air heating, etc. may be appropriately selected.

The rubber composition of the present invention has an excellent balance between rolling resistance and wet grip performance. The rubber composition of the present invention is preferably used as a material for each part of the tire such as a tread (cap tread, base tread), carcass, sidewall, bead portion, etc. of the tire, taking advantage of such characteristics. In particular, in various tires such as all-season tires, high-performance tires, and studless tires, it can be suitably used for tire parts such as treads, carcass, sidewalls, and bead portions, and particularly excellent in low heat generation. Therefore, it can be particularly suitably used for a tread of a fuel-efficient tire, and particularly, it is preferably used for a base tread (under tread).

II. Pneumatic tire Next, the pneumatic tire of the present invention will be described. The pneumatic tire of the present invention is characterized by using the above rubber composition in a tread.

The tread is one that uses the above rubber composition, that is, one that is formed using the rubber composition, and usually contains a cross-linked product of the rubber composition.

Since the rubber composition used for forming such a tread and its cross-linked product can be the same as those described in the above section “I. Rubber composition”, the description thereof is omitted here.

The pneumatic tire only needs to have a tread formed using the rubber composition, and other parts may also be formed using the rubber composition.

The tread formed using the rubber composition may be a part of the tread or the entire tread, but preferably includes at least a base tread.

Moreover, as a manufacturing method of the pneumatic tire of this invention, what is necessary is just a method which can manufacture the pneumatic tire which has the tread formed using the said composition, and using the manufacturing method of a well-known pneumatic tire is used. it can.

The present invention is not limited to the above embodiment. The above-described embodiment is an exemplification, and the present invention has substantially the same configuration as the technical idea described in the claims of the present invention, and any device that exhibits the same function and effect is the present invention. It is included in the technical scope of the invention.

Hereinafter, the present invention will be described more specifically with reference to examples and comparative examples. In addition, the part and% in each example are a mass reference | standard unless there is particular notice.

Various measurements were performed according to the following methods.

[Number average molecular weight, weight average molecular weight, Z average molecular weight and molecular weight distribution]
The hydrocarbon resin used as a sample is subjected to gel permeation chromatography analysis to determine the number average molecular weight (Mn), weight average molecular weight (Mw) and Z average molecular weight (Mz) in terms of standard polystyrene, and the molecular weight distribution is Mw / Mn ratio and Mz / Mw ratio. The gel permeation chromatography analysis uses “HLC-8320GPC” manufactured by Tosoh Corporation as a measuring device, and the column uses three connected “TSKgel SuperMultipore HZ” manufactured by Tosoh Corporation, with tetrahydrofuran as a solvent. , 40 ° C. and a flow rate of 1.0 mL / min.

[Softening point (℃)]
The hydrocarbon resin as a sample was measured according to JIS K 6863.

[Mixed aniline point (℃)]
The hydrocarbon resin as a sample was measured using methylcyclohexane instead of heptane according to JIS K 2256.

[Mooney viscosity (ML1 + 4)]
The rubber composition as a sample was measured according to JIS K 6300-1: 2001 under the following conditions. About this characteristic, it showed with the index | exponent which makes a reference | standard sample (after-mentioned comparative example 1) 100.
Test temperature: 100 ° C
・ Rotor type: L type ・ Testing machine: Shimadzu Mooney Viscometer SMV-300J manufactured by Shimadzu Corporation

[Tensile strength (MPa) and elongation (%)]
About the test piece of the rubber crosslinked material used as a sample, according to JIS K 6251: 2010, tensile strength (tensile stress (MPa)) and elongation (elongation (%)) were measured on condition of the following. About these characteristics, it showed with the index | exponent which makes a reference sample (comparative example 1 mentioned later) 100.
-Test piece preparation method: After sheet preparation by press vulcanization, punching process-Test piece shape: Dumbbell shape No. 3-Specimen sampling direction: Parallel to line arrangement-Number of test pieces: 3
・ Measurement temperature: 23 ℃
・ Test speed: 500 mm / min
・ Testing machine: TENSOMETER 10k manufactured by ALPHA TECHNOLOGIES
・ Test machine capacity: Load cell type 1kN

[Loss tangent tan δ]
The loss tangent tan δ at 0 ° C. and 60 ° C. was measured under the following measurement conditions under the following measurement conditions for the test piece of the crosslinked rubber product as a sample under the following measurement conditions: . About this characteristic, it showed with the index | exponent which makes a reference | standard sample (after-mentioned comparative example 1) 100. The higher the loss tangent tan δ at 0 ° C., the better the wet grip performance, and the lower the loss tangent tan δ at 60 ° C., the better the rolling resistance.
Measurement item: Dynamic storage elastic modulus E '
: Dynamic loss modulus E ''
: Loss tangent tan δ
-Sample preparation method: punching from sheet-Specimen shape: length 50 mm x width 2 mm x thickness 2 mm
・ Number of specimens: 1
・ Distance between clamps: 20mm

[Production Example 1]
A polymerization reactor was charged with a mixture of 56.1 parts of cyclopentane and 15.5 parts of cyclopentene. The temperature was raised to 70 ° C., and then 0.75 part of aluminum chloride was added (mixture M ₁ ). Subsequently, 46.7 parts of 1,3-pentadiene, 18.4 parts of isobutylene, 0.1 part of diisobutylene, 0.1 part of dicyclopentadiene, 0.2 part of C4-C6 unsaturated hydrocarbon, C4-C6 saturated carbonization Mixture a ₁ consisting of 7.2 parts of hydrogen and 19.0 parts of aromatic monoolefin is continuously added to the polymerization reactor containing said mixture M ₁ while maintaining the temperature (70 ° C.) for 60 minutes. Polymerization was carried out. Thereafter, an aqueous sodium hydroxide solution was added to the polymerization reactor to stop the polymerization reaction. Table 1 summarizes the types and amounts of the components in the polymerization reactor during the polymerization reaction. After removing the precipitate generated by the termination of polymerization by filtration, the obtained polymer solution was charged into a distillation kettle and heated in a nitrogen atmosphere to remove the polymerization solvent and unreacted monomers. Subsequently, the low molecular weight oligomer component was distilled off at 240 ° C. or higher while blowing saturated water vapor, and the hydrocarbon resin of Production Example 1 was obtained. For the obtained hydrocarbon resin of Production Example 1, the number average molecular weight, weight average molecular weight, Z average molecular weight, molecular weight distribution, softening point, and mixed aniline point were measured. These measurement results are summarized in Table 1 below.

The aromatic monoolefins contained in the mixture a ₁ are to be included as aromatic monomer. As aromatic monoolefin, 0.95 part of styrene (5.0% by mass in the aromatic monomer) and 18.05 parts of 1-vinylnaphthalene (95.0% by mass in the aromatic monomer) were used. Using.

[Production Examples 2 to 4]
A hydrocarbon resin was obtained in the same manner as in Production Example 1 except that the types and amounts of the components added to the polymerization reactor were changed as shown in Table 1 below. For the obtained hydrocarbon resins of Production Examples 2 to 4, as with the hydrocarbon resin of Production Example 1, the number average molecular weight, weight average molecular weight, Z average molecular weight, molecular weight distribution, softening point and mixed aniline point were measured. . These measurement results are summarized in Table 1 below.

In Production Examples 2 to 4, styrene is used as an aromatic monomer other than the monomer having a structure in which two or more cyclic structures are bonded, as in Production Example 1. In Production Example 3, no aromatic monomer is contained.

[Example 1]
Non-oil-extended emulsion-polymerized styrene-butadiene rubber (SBR) as a styrene-butadiene copolymer rubber in a Banbury type mixer (trade name “Nipol 1502,” manufactured by Nippon Zeon Co., Ltd., Mooney viscosity (ML1 + 4, 100 ° C.): 52) 40 0.0 part and 60.0 parts of natural rubber (NR) (SIR20) were masticated for 30 seconds, and then carbon black having a nitrogen adsorption specific surface area (N ₂ SA) of 115 m ² / g (Nissan Carbon) 50.0 parts of Niteron 300IH (Co., Ltd.) and 10.0 parts of the hydrocarbon resin obtained in Production Example 1, and after kneading for 90 seconds, 3.0 parts of zinc oxide, 1.0 part of stearic acid and Anti-aging agent: 2.0 parts of N-phenyl-N ′-(1,3-dimethylbutyl) -p-phenylenediamine (manufactured by Ouchi Shinsei Co., Ltd., trade name “NOCRACK 6C”) was added, and further 9 Seconds and the mixture was kneaded. Thereafter, the mixture was kneaded at 90 ° C. as a starting temperature, kneaded at 145 ° C. to 155 ° C. for 60 seconds or more (primary kneading), and then the kneaded product was discharged from the mixer.

The obtained kneaded product was cooled to room temperature and then kneaded again (secondary kneading) at 90 ° C. for 2 minutes in a Banbury mixer, and then the kneaded product was discharged from the mixer. The temperature of the kneaded product at the end of kneading was 145 ° C.

Next, with two rolls at 50 ° C., the obtained kneaded product was mixed with 1.7 parts of sulfur and a vulcanization accelerator: N-cyclohexyl-2-benzothiazolylsulfenamide (CBS, trade name “Noxeller CZ- G ”(manufactured by Ouchi Shinsei Chemical Co., Ltd.) was added and kneaded (kneaded with a vulcanizing agent), and then the sheet-like rubber composition was taken out.

The kneading conditions for primary kneading, secondary kneading and vulcanizing agent kneading were as shown below.

(Kneading conditions for primary and secondary kneading)
・ Testing machine: Labo Plast Mill, Banbury mixer B-600 manufactured by Toyo Seiki Seisakusho Co., Ltd.
・ Filling rate: 70-75 vol%
・ Rotor speed: 50rpm
・ Test start set temperature: 90 ℃

(Kneading conditions for vulcanizing agent)
・ Testing machine: Ikeda Machine Industries Co., Ltd. electric heating type high temperature roll machine ・ Roll size: 6φ × 16
-Front roll speed: 24rpm
-Front / rear roll rotation ratio: 1: 1.22
・ Roll temperature: 50 ℃ ± 5 ℃
・ Number of turn-over: Twice left and right ・ Rounding width: Roll interval approx. 0.8mm
・ Number of rounding: 5 times

[Examples 2 to 3 and Comparative Examples 1 to 7]
As shown in Table 2 below, a rubber composition was obtained in the same manner as in Example 1 except that the type and blending amount of the hydrocarbon resin and the type and blending amount of carbon black were adjusted.

In Comparative Example 5, carbon black having a nitrogen adsorption specific surface area (N ₂ SA) of 65 m ² / g (Cibot Black N330T manufactured by Cabot Japan Co., Ltd.) was used. In Comparative Example 6, carbon black (# 3400B manufactured by Mitsubishi Chemical Corporation) having a nitrogen adsorption specific surface area (N ₂ SA) of 165 m ² / g was used.

[Evaluation]
The rubber compositions obtained in the examples and comparative examples were press-crosslinked at a press pressure of about 8 MPa and a press temperature of 160 ° C. for 40 minutes, and then aged overnight in a thermostatic chamber at 23 ° C., and then 150 mm × 150 mm × thickness. A test piece of 2 mm rubber cross-linked product was prepared.

For the rubber compositions and rubber cross-linked products obtained in Examples and Comparative Examples, the Mooney viscosity of the rubber composition, the tensile strength (MPa), the elongation (%), and the loss tangent tan δ of the rubber cross-linked product were measured. The results are shown in Table 2 below.

From Tables 1 and 2, it was confirmed that the loss tangent tan δ at 0 ° C. was high and the loss tangent tan δ at 60 ° C. was low in the examples. From this result, it was confirmed that both the rolling resistance and the wet grip performance were excellent. In addition, when a diene rubber and hydrocarbon resin are included, the rubber composition is excellent in both rolling resistance and wet grip performance. It was confirmed that Further, when the rubber composition has carbon black having a predetermined nitrogen adsorption specific surface area (N ₂ SA) as the carbon black, both the rolling resistance and the wet grip performance can be obtained by improving the dispersibility of the carbon black. It was confirmed that this was excellent.

That is, from Table 1 and Table 2, those having a predetermined proportion of monomer units having a structure in which two or more cyclic structures are bonded, and having characteristics such as a predetermined weight average molecular weight (Mw) and softening point In particular, for example, a hydrocarbon resin having a moderately low weight average molecular weight (Mw) and a ratio (Mw / Mn) of the weight average molecular weight to the number average molecular weight (Mn) and a moderately high softening point is obtained with a predetermined nitrogen adsorption ratio. By including a predetermined amount with respect to the diene rubber together with carbon black having a surface area (N ₂ SA), the rubber composition may be excellent in processability and excellent in both rolling resistance and wet grip performance. It could be confirmed.

Claims (5)

1. For 100 parts by mass of diene rubber consisting of 30 parts by mass to 90 parts by mass of natural rubber and 10 parts by mass to 70 parts by mass of styrene-butadiene copolymer rubber
   A rubber composition comprising 1 part by mass to 30 parts by mass of a hydrocarbon resin and 20 parts by mass to 80 parts by mass of carbon black having a nitrogen adsorption specific surface area (N ₂ SA) in the range of 70 m ² / g to 150 m ² / g. Is a thing,
   The hydrocarbon resin is
   An aliphatic monomer unit and an aromatic monomer unit,
   A content of the monomer unit having a structure in which two or more cyclic structures are bonded in the aromatic monomer unit in the aromatic monomer unit is 50% by mass or more,
   A rubber composition having a weight average molecular weight (Mw) in a range of 700 to 6000 and a softening point in a range of 80 ° C to 150 ° C.
2. The hydrocarbon resin is
   1,3-pentadiene monomer unit 10 mass% to 60 mass%,
   1 to 30% by mass of an alicyclic monoolefin monomer unit having 4 to 6 carbon atoms,
   1 to 50% by mass of an acyclic monoolefin monomer unit having 4 to 8 carbon atoms,
   Including 0% by mass to 10% by mass of the alicyclic diolefin monomer unit, and 0.1% by mass to 50% by mass of the aromatic monomer unit,
   The number average molecular weight (Mn) is in the range of 400 to 3000,
   The Z average molecular weight (Mz) is in the range of 1500-20000,
   The ratio of the weight average molecular weight to the number average molecular weight (Mw / Mn) is in the range of 1.0 to 4.0,
   The rubber composition according to claim 1, wherein the ratio of the Z average molecular weight to the weight average molecular weight (Mz / Mw) is in the range of 1.0 to 4.0.
3. The monomer having a structure in which two or more cyclic structures are bonded is at least one selected from the group consisting of naphthalene compounds, fluorene compounds, biphenyl compounds, anthracene compounds, phenanthrene compounds, indene compounds, and benzothiophene compounds. The rubber composition according to claim 1 or 2, characterized by the above.
4. The hydrocarbon resin has a mixed aniline point value of 25 ° C. to 100 ° C. measured at the lowest temperature at which a mixed solution (volume ratio 2: 1: 1) of aniline, methylcyclohexane and the hydrocarbon resin exists as a homogeneous solution. The rubber composition according to any one of claims 1 to 3, wherein the rubber composition is within a range of ° C.
5. A pneumatic tire using the rubber composition according to any one of claims 1 to 4 for a tread.