JP7081495B2 - Rubber composition and pneumatic tires - Google Patents

Description

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

In recent years, tires for automobiles are strongly required to have low fuel consumption due to environmental problems and resource problems, while improvement of wet grip property is required from the viewpoint of safety, for example. A crosslinked product of a rubber composition containing silica as a filler in a rubber component (hereinafter, may be simply referred to as a rubber crosslinked product) constitutes a tire as compared with a crosslinked product of a rubber composition containing carbon black. The rolling resistance is reduced when the rubber is used. Therefore, by constructing a tire using a crosslinked product of a rubber composition containing silica, a tire having excellent fuel efficiency can be obtained.

However, even if silica is blended with the conventional rubber component, the affinity between the rubber component and silica is insufficient, and the rubber composition before crosslinking is poorly processable due to the fact that these are easily separated. Further, the rubber crosslinked product obtained by cross-linking the tire has a problem that the rolling resistance is insufficient when the tire is configured.

Further, in Patent Document 1, for the purpose of improving the rolling resistance and wet grip property of the tire, a specific amount of a softener having a specific structure is blended in the rubber component, and a specific amount of a hydrocarbon resin having a specific structure is blended. It is disclosed to do.

Japanese Unexamined Patent Publication No. 2010-241965

The softener and the hydrocarbon resin having the specific structure described in Patent Document 1 certainly improve both the wet grip property and the rolling resistance when the tire is manufactured by the rubber crosslinked product obtained by adding them. It is possible, but there is a problem that it is still insufficient.

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

As a result of diligent studies on a hydrocarbon resin that provides a rubber composition having excellent workability and an excellent balance between rolling resistance and wet grip performance, the present inventors have a structure in which two or more cyclic structures are bonded. A hydrocarbon resin containing a predetermined ratio of monomer units and having predetermined characteristics such as a weight average molecular weight within a predetermined range improves the workability of the rubber composition, and has rolling resistance and wet grip performance. We have found that it is involved in the well-balanced improvement of both performances, and have completed the present invention.

Thus, according to the present invention, the rubber composition is obtained by blending 1 part by mass to 30 parts by mass of a hydrocarbon resin and 80 parts by mass to 200 parts by mass of silica with 100 parts by mass of a diene rubber. The resin contains 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 of the aromatic monomer units are bonded. The rubber is characterized in that the content in the body unit is 50% by 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. The composition is provided.

The above-mentioned hydrocarbon resin contains 10% by mass to 60% by mass of a 1,3-pentadiene monomer unit, 1% by mass to 30% by mass of an alicyclic monoolefin monomer unit having 4 to 6 carbon atoms, and 4 to 30% by mass of 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 It contains 50% by mass, 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 /). It is preferable that Mn) is 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 in the range of 1.0 to 4.0.

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

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

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

INDUSTRIAL APPLICABILITY The present invention has an effect of being able to provide a rubber composition having excellent processability and an excellent balance between rolling resistance and wet grip performance.

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

I. Rubber Composition The rubber composition of the present invention is a rubber composition obtained by blending 1 part by mass to 30 parts by mass of a hydrocarbon resin and 80 parts by mass to 200 parts by mass of silica with 100 parts by mass of diene-based rubber. The hydrocarbon resin contains an aliphatic monomer unit and an aromatic monomer unit, and the aromatic of the monomer unit having a structure in which two or more cyclic structures of the aromatic monomer units are bonded. It is characterized in that the content in the group monomer unit is 50% by 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. Is to be.

According to the present invention, the rubber composition contains an aliphatic monomer unit and an aromatic monomer unit, and has a structure in which two or more cyclic structures of the aromatic monomer units are bonded to each other. By containing a hydrocarbon resin containing a predetermined ratio of body units and having characteristics such as a predetermined weight average molecular weight and a softening point in a predetermined amount together with silica with respect to the diene rubber, the processability is excellent and the processability is excellent. A rubber composition having an excellent balance between rolling resistance and wet grip performance can be obtained.

Here, it is not clear why a rubber composition having excellent processability and an excellent balance between rolling resistance and wet grip performance can be obtained by using the above-mentioned hydrocarbon resin, but as follows. Inferred. That is, a hydrocarbon resin containing a monomer unit having a structure in which the above two or more cyclic structures are bonded is used as the aromatic monomer unit in a predetermined ratio, and the hydrocarbon resin further has the above-mentioned predetermined characteristics. The hydrocarbon resin can have a moderately low weight average molecular weight (Mw) and a moderately high softening point. Therefore, the above-mentioned hydrocarbon resin has excellent compatibility with the diene-based rubber, and for example, uniform mixing with the diene-based rubber is facilitated, so that the obtained rubber composition is excellent in processability. Further, with respect to the obtained rubber composition, the loss coefficient 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 for a tread is manufactured, it is possible to form a pneumatic tire having an excellent balance between rolling resistance and wet grip performance.

From the above, by containing the above-mentioned hydrocarbon resin in a predetermined amount with respect to the diene-based rubber, it is possible to obtain a rubber composition having excellent processability and an excellent balance between rolling resistance and wet grip performance. ..

Further, the rubber composition further contains a predetermined amount of silica, so that a rubber composition having an excellent balance between rolling resistance and wet grip performance can be obtained. On the other hand, if the blending amount of the silica is less than 80 parts by mass, the wet grip performance is deteriorated, and if it is more than 200 parts by mass, the rolling resistance is deteriorated. On the other hand, when the blending amount of silica is 80 parts by mass or more, the processability deteriorates. Therefore, by containing the hydrocarbon resin in a predetermined amount together with silica, the rubber composition can suppress a decrease in processability and improve the balance between rolling resistance and wet grip performance.

For these reasons, the rubber composition contains the hydrocarbon resin in a predetermined amount together with silica with respect to the diene rubber, so that the rubber composition is excellent in processability and has an excellent balance between rolling resistance and wet grip performance. It becomes a thing.

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

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

1. 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 usually has 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, the structure in which two or more cyclic structures are bonded may be any one containing one or more aromatic rings among the two or more cyclic structures, and even if it contains only an aromatic ring, it is aromatic. It may include a ring and a non-aromatic ring structure.

As the aliphatic carbon-carbon unsaturated bond, any one having radical polymerizable property may be used, and a vinyl group can be preferably used.

The aliphatic carbon-carbon unsaturated bond may be contained as a part of the cyclic structure, such as the vinylene group contained in the five-membered ring of Inden, or the vinyl group contained in 1-vinylnaphthalene. It may be bonded to a cyclic structure as in. In the present invention, it is particularly preferable that the aliphatic carbon-carbon unsaturated bond is contained 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 the aliphatic carbon-carbon unsaturated bond is contained as a part of the cyclic structure, the cyclic structure is a non-aromatic ring structure.

When the aliphatic carbon-carbon unsaturated bond is contained as a part of the cyclic structure, the carbon number of the cyclic structure containing the aliphatic carbon-carbon unsaturated bond as a part thereof has a desired property. Any material may be used as long as it can form the hydrocarbon resin to have, for example, it may be in the range of 4 to 8, but it is particularly preferable that it is in the range of 4 to 6. When the monomer having a structure in which two or more cyclic structures are bonded is inden, the aliphatic carbon-carbon unsaturated bond is contained as a part of the five-membered ring of inden as described above, and the above fat. The cyclic structure containing a group carbon-carbon unsaturated bond as a part has five carbon atoms.

When the aliphatic carbon-carbon unsaturated bond is bonded to a cyclic structure, the aliphatic carbon-carbon unsaturated bond has a cyclic structure like the vinyl group contained in 1-vinylnaphthalene. It may be directly bonded to the ring, or may be bonded to the cyclic structure via a spacer, such as the 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 a 1-butenyl group, a carbonyl group bonded to a vinyl group such as an acrylic loyl group and a metaacryloyl group, and the like. can.

The carbon number of the spacer may be any as long as it can form a hydrocarbon resin having desired characteristics, and may be, for example, in the range of 1 to 3.

The number contained in the monomer having a structure in which two or more cyclic structures of the aliphatic carbon-carbon unsaturated bond are bonded is usually one or more, and is, for example, in the range of 1 to 2. It can be, but preferably one. The number of the aliphatic carbon-carbon unsaturated bonds is the number of each monomer when two or more kinds of monomers are included as the monomers having a structure in which the two or more cyclic structures are bonded. It refers to the number of aliphatic carbon-carbon unsaturated bonds contained.

The structure in which two or more cyclic structures are bonded includes a structure in which cyclic structures form a fused ring group, such as a naphthalene structure, a fluorene structure, an anthracene structure, a phenanthrene structure, a benzothiophene structure, and an inden, and a biphenyl structure. , A group in which cyclic structures are directly connected by a single bond such as a turphenyl structure, or a group in which cyclic structures form a fused ring group and a group in which cyclic structures are directly connected by a single bond are formed. Those including both of them can be mentioned.

Examples of the structure in which two or more cyclic structures are bonded include only an aromatic ring include a naphthalene structure, a biphenyl structure, an anthracene structure, a phenanthrene structure, a benzothiophene structure, and the like, and include an aromatic ring and a non-aromatic ring. Examples of those including a group-like ring structure include a fluorene structure and an inden structure.

In the present invention, it is preferable that the structure in which the two or more cyclic structures are bonded includes an aromatic ring and a non-aromatic ring structure. Since the structure in which the two or more cyclic structures are bonded includes an aromatic ring and a non-aromatic ring structure as the cyclic structure, the hydrocarbon resin is excellent in processability, and has excellent rolling resistance and wet grip performance. This is because it is possible to provide a rubber composition having an excellent balance between the above.

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

Further, the cyclic structure may have a substituent. Examples of substituents are halogen atom (F, Cl, Br, I), hydroxyl group, carboxyl group, cyano group, amino group, nitro group, sulfo group, carbamoyl group, sulfamoyl group, ureido group, alkyl group, alkenyl. Group, alkynyl group, aliphatic acyl group, aliphatic acyloxy group, alkoxy group, alkoxycarbonyl group, alkoxycarbonylamino group, alkylthio group, alkylsulfonyl group, aliphatic amide group, aliphatic sulfonamide group, aliphatic substituted amino group , An aliphatic substituted carbamoyl group, an aliphatic substituted sulfamoyl group, an aliphatic substituted ureido group and the like can be mentioned as typical examples.

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

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 the above 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, it is preferably an indene compound, and particularly preferably indene. Since the monomer having a structure in which the two or more cyclic structures are bonded is the above-mentioned compound, the above-mentioned hydrocarbon resin has a rubber composition excellent in workability and an excellent balance between rolling resistance and wet grip performance. Because you 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 thereof, for example, 1-vinylnaphthalene, 2-vinylnaphthalene, allylnaphthalene, butenyl. Naphthalene and the like can be mentioned.

Examples of the fluorene compound include those having a fluorene structure and one or more aliphatic carbon-carbon unsaturated bonds in the molecular structure thereof, for example, 2,7-divinylfluorene, 2-vinylfluorene, allylfluorene, and the like. Butenyl fluorene and the like can be mentioned.

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

Examples of the anthracene compound include those having an anthracene structure and one or more aliphatic carbon-carbon unsaturated bonds in the molecular structure thereof, and examples thereof include 9-vinyl anthracene, 2-vinyl anthracene, and 9,10-divinyl. Anthracene, allylanthracene, butenyl anthracene and the like 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 thereof, and examples thereof include 9-vinylphenanthrene and 3-vinylphenanthrene. ..

The indene compound may be any indene compound having an indene structure in its molecular structure, for example, indene, methyl indene, ethyl indene, propyl indene, butyl indene, t-butyl indene, sec-butyl indene, n-pentyl. Indene, 2-methyl-butyl indene, 3-methyl-butyl indene, n-hexyl indene, 2-methyl-pentyl indene, 3-methyl-pentyl indene, 4-methyl-pentyl indene and other alkyl substituted indenes are mentioned. Can be done.

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

The monomer having a structure in which two or more types of cyclic structures are bonded may contain only one type of monomer, or may contain a mixture of two or more types of monomers. good. For example, the monomer having a structure in which the above 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 in the aromatic monomer unit of the monomer unit having a structure in which the above two or more cyclic structures are bonded may be 50% by mass or more, and is in the range of 55% by mass to 99.9% by mass. 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. This is because when the content is within the above range, the hydrocarbon resin can provide a rubber composition having excellent processability and a good balance between rolling resistance and wet grip performance.

The aromatic monomer unit includes a monomer unit having a structure in which two or more cyclic structures are bonded, but in addition to the monomer unit having a structure in which two or more cyclic structures are bonded, one It may contain a monomer unit containing only a cyclic structure, that is, a monomer unit containing only one aromatic ring as a cyclic structure. Examples of the monomer constituting the monomer unit containing only one cyclic structure include styrene, α-methylstyrene, vinyltoluene and the like.

As for the content of the aromatic monomer unit in the hydrocarbon resin, the hydrocarbon resin can provide a rubber composition having excellent processability and a good balance between rolling resistance and wet grip performance. Anything may be sufficient, 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 particularly 8% by mass to 43% by mass. It is preferably in the range of 10% by mass to 40% by mass, and particularly preferably in the range of 10% by mass to 40% by mass. This is because when the content is within the above range, the hydrocarbon resin can provide a rubber composition having excellent processability and a good balance between rolling resistance and wet grip performance.

2. 2. Aliphatic Monomer Unit As the aliphatic monomer unit in the present invention, it is possible to provide a rubber composition which exhibits the above-mentioned predetermined characteristics, is excellent in processability, and has an excellent balance between rolling resistance and wet grip performance. Any material may be used as long as it can form a possible hydrocarbon resin.

The aliphatic monomer unit may be any as long as it does not contain an aromatic ring. For example, an alicyclic monoolefin monomer having 1,3-pentadiene monomer unit and 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 contained. For example, as an aliphatic monomer unit, 1,3-pentadiene monomer unit 10% by mass to 60% by mass and 1 mass of an alicyclic monoolefin monomer unit having 4 to 6 carbon atoms in a hydrocarbon resin. It may contain% to 30% by mass, 1% by mass to 50% by mass of an acyclic monoolefin monomer unit having 4 to 8 carbon atoms, and 0% to 10% by mass of an alicyclic diolefin monomer unit. can.

As the content of the 1,3-pentadiene monomer unit in the hydrocarbon resin, a hydrocarbon resin capable of providing a rubber composition having excellent processability and an excellent balance between rolling resistance and wet grip performance can be provided. Anything that can be obtained may be used, for example, it may 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 particularly in the range of 20% by mass to 55% by mass. It is preferably in the range of 50% by mass, and particularly preferably in the range of 25% by mass to 48% by mass. This is because when the content is within the above range, the hydrocarbon resin can provide a rubber composition having excellent processability and a good balance between rolling resistance and wet grip performance.

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

An 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. be. Specific examples of the alicyclic monoolefin having 4 to 6 carbon atoms include cyclobutene, cyclopentene, cyclohexene, methylcyclobutene, and methylcyclopentene.

As the content of the alicyclic monoolefin monomer unit having 4 to 6 carbon atoms in the hydrocarbon resin, a rubber composition having excellent processability and an excellent balance between rolling resistance and wet grip performance is provided. It suffices as long as it is possible to obtain a hydrocarbon resin capable of producing a hydrocarbon resin, 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. This is because when the content is within the above range, the hydrocarbon resin can provide a rubber composition having excellent processability and a good balance between rolling resistance and wet grip performance.

In the alicyclic monoolefin having 4 to 6 carbon atoms, the proportion of each compound corresponding to this may be any ratio, and is not particularly limited, but at least cyclopentene is preferably contained, and the alicyclic monoolefin has 4 to 6 carbon atoms. It is more preferable that the proportion of cyclopentene in the alicyclic monoolefin is 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 has no ring structure and has a chain hydrocarbon compound having 4 to 8 carbon atoms. Is. Specific examples of acyclic monoolefins 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 , 2-Methyl-1-heptene and other heptenes; 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) can be mentioned.

As the content of the acyclic monoolefin monomer unit having 4 to 8 carbon atoms in the hydrocarbon resin, a rubber composition having excellent processability and an excellent balance between rolling resistance and wet grip performance is provided. It suffices as long as it is possible to obtain a hydrocarbon resin capable of producing a hydrocarbon, for example, it can be in the range of 1% by mass to 50% by mass, and preferably in the range of 5% by mass 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. This is because when the content is within the above range, the hydrocarbon resin can provide a rubber composition having excellent processability and a good balance between rolling resistance and wet grip performance.

In the acyclic monoolefin having 4 to 8 carbon atoms, the ratio of each compound (including an isomer) corresponding to this may be any ratio, and is not particularly limited, but at least 2-methyl-2-butene. It is preferable that at least one selected from the group consisting of isobutylene and diisobutylene is contained, and the total amount of 2-methyl-2-butene, isobutylene and diisobutylene occupies in the alicyclic monoolefin having 4 to 6 carbon atoms. It is more preferable that the ratio is 50% by mass or more.

The hydrocarbon resin may contain an alicyclic diolefin as a raw material thereof. The 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 a multimer of cyclopentadiene such as cyclopentadiene and dicyclopentadiene, and a multimer of methylcyclopentadiene and methylcyclopentadiene.

As the content of the alicyclic diolefin monomer unit in the hydrocarbon resin, a hydrocarbon resin capable of providing a rubber composition having excellent processability and an excellent balance between rolling resistance and wet grip performance can be provided. Anything that can be obtained may be used, for example, it may be in the range of 0% by mass to 10% by mass, preferably in the range of 0% by mass to 7% by mass, and above all, 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. This is because when the content is within the above range, the hydrocarbon resin can provide a rubber composition having excellent processability and a good balance between rolling resistance and wet grip performance.

The aliphatic monomer unit is a 1,3-pentadiene monomer unit, an alicyclic monoolefin monomer unit having 4 to 6 carbon atoms, and an acyclic monoolefin monomer unit having 4 to 8 carbon atoms. In addition to the alicyclic diolefin monomer unit, other hydrocarbon resins that provide a rubber composition having excellent processability and an excellent balance between rolling resistance and wet grip performance can be obtained. It may contain a monomeric unit. The other monomer used to form such another monomer unit may be a compound having an addition-polymerizable property that can be addition-copolymerized with 1,3-pentadiene or the like other than the above-mentioned monomer. However, it is not particularly limited. The other monomers include, for example, 1,3-butadiene, 1,2-butadiene, isoprene, 1,3-hexadiene, 1,4-pentadiene and the like, and have 4 to 6 carbon atoms other than 1,3-pentadiene. Unsaturated hydrocarbons; alicyclic monoolefins having 7 or more carbon atoms such as cycloheptene; acyclic monoolefins other than 4 to 8 carbon atoms such as ethylene, propylene and benzene are included.

However, the content of the other monomer units in the hydrocarbon resin may be any as long as it can obtain a hydrocarbon resin having the above-mentioned predetermined characteristics. 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 an excellent balance between rolling resistance and wet grip performance.

As for the content of the aliphatic monomer unit in the hydrocarbon resin, the hydrocarbon resin can provide a rubber composition having excellent processability and a good balance between rolling resistance and wet grip performance. It may be, for example, 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. This is because when the content is within the above range, the hydrocarbon resin can provide a rubber composition having excellent processability and a good balance between rolling resistance and wet grip performance.

3. 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 preferably in the range of 900 to 5000. It is more preferably in the range of 1000 to 4000. This is because the hydrocarbon resin can be made excellent in compatibility with the diene-based rubber when the weight average molecular weight (Mw) is within the above range. Further, as a result, the hydrocarbon resin can easily have a low loss coefficient tan δ at 60 ° C. for the crosslinked product of the rubber composition, and can have excellent rolling resistance. Further, when the weight average molecular weight (Mw) is within the above range, the hydrocarbon resin can easily increase the loss coefficient tan δ at 0 ° C. and can be excellent in 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, and particularly in the range of 500 to 2000. Is more preferable. This is because the hydrocarbon resin can be made excellent in compatibility with the diene-based rubber when the number average molecular weight (Mn) is within the above range. Further, as a result, the hydrocarbon resin can easily have a low loss coefficient tan δ at 60 ° C. for the crosslinked product of the rubber composition, and can have excellent 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, and particularly in the range of 2000 to 10000. Is more preferable. This is because the hydrocarbon resin can be made excellent in compatibility with the diene-based rubber when the Z average molecular weight (Mz) is within the above range. Further, as a result, the hydrocarbon resin can easily have a low loss coefficient tan δ at 60 ° C. for the crosslinked product of the rubber composition, and can have excellent 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-equivalent values measured by high-speed liquid chromatography. More specifically, the measurement of the number average molecular weight, the weight average molecular weight and the Z average molecular weight uses "HLC-8320GPC" manufactured by Tosoh Co., Ltd. as a measuring device, and three columns "TSKgel SuperMultipore HZ" manufactured by Tosoh Co., Ltd. are connected. It can be measured at a flow rate of 1.0 mL / min at 40 ° C. using tetrahydrofuran as a solvent.

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 in particular, in the range of 1.1 to 3.5. It is preferably in the range of 1.2 to 3.0, and more preferably in the range of 1.2 to 3.0. This is because when the above ratio is within the above range, the hydrocarbon resin can be made excellent in compatibility with the diene-based rubber. Further, as a result, the hydrocarbon resin can easily have a low loss coefficient tan δ at 60 ° C. for the crosslinked product of the rubber composition, and can be excellent in wet grip performance.

The ratio (Mz / Mw) of the Z average molecular weight to the weight average molecular weight of the hydrocarbon resin can be in the range of 1.0 to 4.0, and in particular, in the range of 1.1 to 3.5. It is preferably in the range of 1.2 to 3.0, and more preferably in the range of 1.2 to 3.0. This is because when the above ratio is within the above range, the hydrocarbon resin can be made excellent in compatibility with the diene-based rubber. Further, as a result, the hydrocarbon resin can easily have a low loss coefficient tan δ at 60 ° C. for the crosslinked 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., but it is particularly preferably in the range of 85 ° C. to 145 ° C., particularly 90 ° C. to 90 ° C. It is more preferably in the range of 140 ° C. This is because the hydrocarbon resin can be made excellent in compatibility with the diene-based rubber when the softening point is within the above range. Further, as a result, the hydrocarbon resin can easily have a low loss coefficient tan δ at 60 ° C. for the crosslinked product of the rubber composition, and can have excellent rolling resistance. Further, since the softening point is within the above range, the hydrocarbon resin can easily increase the loss coefficient tan δ at 0 ° C. and can be excellent in wet grip performance. ..

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

The mixed aniline point (MMAP) of the hydrocarbon resin can be in the range of 25 ° C to 100 ° C, and more preferably in the range of 27 ° C to 90 ° C, particularly 30 ° C to 75 ° C. It is more preferable that it is within the range of. This is because the hydrocarbon resin can be made excellent in compatibility with the diene-based rubber when the mixed aniline point is within the above range. Further, as a result, the hydrocarbon resin can easily have a low loss coefficient tan δ at 60 ° C. for the crosslinked product of the rubber composition, and can have excellent rolling resistance. Further, 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 be excellent in wet grip performance. be.

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

The blending amount of the hydrocarbon resin is not particularly limited as long as it is 1 part by mass to 30 parts by mass with respect to 100 parts by mass of the diene-based rubber, but among them, 5 with respect to 100 parts by mass of the diene-based rubber. It is preferably in the range of 20 parts by mass to 20 parts by mass. This is because when the blending amount is within the above range, the rubber composition is excellent in processability and has an excellent balance between rolling resistance and wet grip performance.

The blending amount of the hydrocarbon resin is preferably in the range of 1% by mass to 30% by mass, and more preferably in the range of 3% by mass to 25% by mass. ..

4. Method for Producing Hydrocarbon Resin The method for producing a hydrocarbon resin may be any method as long as it can obtain a hydrocarbon resin containing an aliphatic monomer unit and an aromatic monomer unit. Preferred examples thereof include a method of addition polymerization of a polymerizable component (monomer mixture A) having a monomer capable of constituting a weight unit and an aromatic monomer unit.

For example, a hydrocarbon resin can be obtained by addition polymerization using a Friedel-Crafts type cationic polymerization catalyst. Suitable methods for producing hydrocarbon resins include aluminum halide (A), halogenated hydrocarbons (B1) in which a halogen atom is bonded to a tertiary carbon atom, and carbon-carbon non-carbon atoms, as described below. The above-mentioned aliphatic monomer and the above-mentioned aliphatic monomer and the above-mentioned aliphatic monomer are combined 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 a saturated bond to form a polymerization catalyst. Examples thereof include a method having a polymerization step of polymerizing a monomer mixture A containing an aromatic monomer.

Further, the amount of each monomer added to 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, the 1,3-pentadiene monomer unit is 10% by mass to 60% by mass, and the alicyclic monoolefin monomer unit having 4 to 6 carbon atoms is 1% by mass to 30% by mass. It contains 1% by mass to 50% by mass of an acyclic monoolefin monomer unit having 4 to 8 carbon atoms and 0% by mass to 10% by mass of an alicyclic diolefin monomer unit, and has 0 aromatic monomer units. .In the case of producing a hydrocarbon resin containing 1% by mass to 50% by mass, the above-mentioned production method is more specifically described in that the 1,3-pentadiene monomer is 10% by mass to 60% by mass and has 4 to 6 carbon atoms. Alicyclic monoolefin monomer 1% by mass to 30% by mass, acyclic monoolefin monomer having 4 to 8 carbon atoms 1% by mass to 50% by mass, alicyclic diolefin monomer 0% by mass to The content of the monomer having a structure in which 10% by mass and two or more cyclic structures are bonded is 50% by mass or more in the aromatic monomer, and the above-mentioned aromatic monomer is 0.1% by mass to 50% by mass. It is possible to have a polymerization step of polymerizing the monomer mixture A containing%.

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 and the like.

The amount of the aluminum halide (A) used is not particularly limited, but is preferably in the range of 0.05 parts by mass to 10 parts by mass, more preferably with respect to 100 parts by mass of the polymerizable component (monomer mixture A). It is in the range of 0.1 parts by mass 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 carbon-carbon conjugated double bonds in such cases. 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-butine, and the like. Benzyl chloride can be mentioned. Among these, benzyl chloride is preferably used because it has an excellent balance between activity and ease of handling. The halogenated hydrocarbon (B) may be used alone or in combination of two or more.

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 with respect to the aluminum halide (A).

In carrying out the polymerization reaction, the order in which the respective components of the monomer mixture and the polymerization catalyst are added to the polymerization reactor is not particularly limited and may be added in any order, but the polymerization reaction may be well controlled. From the viewpoint of more accurately controlling the weight average molecular weight, etc., a monomer mixture and a part of the components of the polymerization catalyst are added to the polymerization reactor, the polymerization reaction is started, and then the rest of the polymerization catalyst is polymerized. It is preferable to add it to the vessel.

In the production of the hydrocarbon resin, when the alicyclic monoolefin monomer unit is contained as the aliphatic monomer unit, the aluminum halide (A) and the alicyclic monoolefin may be mixed first. preferable. This is because by contacting the aluminum halide (A) with the alicyclic monoolefin, the formation of a gel can be prevented, and a hydrocarbon resin having an accurately controlled weight average molecular weight and the like can be obtained.

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

When the aluminum halide (A) and the alicyclic monoolefin are mixed, the order of charging is not particularly limited, and the aluminum halide (A) may be charged into the alicyclic monoolefin, or conversely. An alicyclic monoolefin may be added to the halogenated aluminum (A). Mixing is usually accompanied by exotherm, so suitable diluents can also be used. As the diluent, a solvent described later can be used.

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

The method for preparing the mixture a is not particularly limited, and each pure compound may be mixed to obtain the desired mixture a, or a mixture containing the desired monomer derived from, for example, a fraction of a naphtha decomposition product. May be used to obtain the desired mixture a. For example, in order to add 1,3-pentadiene or the like to the mixture a, the C5 fraction after extracting isoprene and cyclopentadiene (including a multimer thereof) can be preferably used.

It is preferable to further mix the halogenated hydrocarbon (B) with the mixture a and the mixture M. The input order of these three parties is not particularly limited.

From the viewpoint of better controlling the polymerization reaction, it is preferable to add a solvent to the polymerization reaction system to carry out the polymerization reaction. The type of 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 saturated aliphatic hydrocarbons used as a 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. 5 to 10 chain saturated aliphatic hydrocarbons; examples include cyclic saturated aliphatic hydrocarbons in the range of 5 to 10 carbon atoms such as cyclopentane, cyclohexane, cycloheptane, and cyclooctane. Examples of the aromatic hydrocarbon used as the solvent include aromatic hydrocarbons having 6 to 10 carbon atoms such as benzene, toluene and xylene. As the solvent, one type may be used alone, or two or more types may be used as a mixed solvent. The amount of the solvent used is not particularly limited, but is preferably in the range of 10 parts by mass to 1,000 parts by mass, and 50 parts by mass to 100 parts by mass with respect to 100 parts by mass of the polymerizable component (monomer mixture A). It is more preferably in the range of 500 parts by mass. In addition, 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 distillate, is added to the polymerization reaction system, and the addition-polymerizable component is a single amount. It can also be used as a component of the body mixture and the non-additionally polymerizable component as a solvent.

The polymerization temperature at the time of 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 lowered and the productivity may be deteriorated, and if the polymerization temperature is too high, the controllability such as the weight average molecular weight of the obtained hydrocarbon resin may be poor. The pressure at which the polymerization reaction is carried out may be under atmospheric pressure or under pressure. The polymerization reaction time can be appropriately selected, but is usually selected in 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 solution of sodium hydroxide, or an aqueous solution of ammonia to the polymerization reaction system when the desired polymerization conversion rate is obtained.

The method for producing a hydrocarbon resin has at least the above-mentioned polymerization step, but may have other steps, if necessary. As the above other steps, for example, after the polymerization step, a catalyst residue obtained by adding a polymerization terminator in the polymerization step to inactivate the polymerization catalyst and removing the solvent-insoluble catalyst residue by filtration or the like is removed. After the polymerization reaction is stopped by the removal step and the polymerization step, the unreacted monomer and solvent are removed, and the low molecular weight oligomer component is removed by steam distillation or the like and cooled to obtain a solid resin. And so on.

B. Diene-based rubber As the diene-based rubber, any diene-based rubber that can be blended with a hydrocarbon resin and silica in the rubber composition can be used. As such a diene-based rubber, for example, the diene-based rubber described in Japanese Patent Application Laid-Open No. 2015-189873 can be used. More specifically, the diene rubber includes natural rubber (NR), isoprene rubber (IR), butadiene rubber (BR), styrene-butadiene copolymer rubber (SBR), and acrylonitrile-butadiene copolymer rubber (NBR). ), Ethylene-propylene-dienter polymer (EPDM) and the like, and among them, styrene-butadiene copolymer rubber, natural rubber and the like are preferable. This is because the diene-based rubber makes it possible to obtain a rubber composition having excellent workability and a good balance between rolling resistance and wet grip performance. The diene-based rubber may contain at least one type, may contain only one type, or may be used as a mixture of two or more types.

Further, the diene-based rubber is not particularly limited in its molecular weight and microstructure, and may be terminal-modified with an amine, amide, silyl, alkoxysilyl, carboxyl, hydroxyl group or the like, or may be epoxidized. The diene-based rubber may be hydrogenated, but is preferably not hydrogenated.

C. Silica The silica is blended in a rubber composition together with a diene rubber and a hydrocarbon resin.

By blending such silica together with a diene-based rubber and the above-mentioned hydrocarbon resin in a rubber composition, a rubber composition having excellent processability and an excellent balance between rolling resistance and wet grip performance is provided. Any material can be used as long as it can be used, and for example, the same silica as described in JP-A-2016-3274 can be used. More specifically, dry silica, wet silica, colloidal silica, precipitated silica and the like can be used as the silica. Moreover, the type of silica may be used alone or in combination of two or more.

The BET specific surface area of the silica (measured according to ISO5794 / 1) can be in the range of 100 m ² / g to 400 m ² / g, and in particular, in the range of 150 m ² / g to 350 m ² / g. It is preferably inside.

The blending amount of the silica is not particularly limited as long as it is 80 parts by mass to 200 parts by mass with respect to 100 parts by mass of the diene rubber, but 90 parts by mass with respect to 100 parts by mass of the diene rubber. It is preferably in the range of up to 150 parts by mass. This is because when the blending amount is within the above range, the rubber composition is excellent in processability and has an excellent balance between rolling resistance and wet grip performance.

D. Other Ingredients The rubber composition of the present invention contains a diene-based rubber, a hydrocarbon resin and silica, but may contain other ingredients as necessary. Examples of the above other components include compounding agents such as silane coupling agents, cross-linking agents, cross-linking accelerators, cross-linking activators, anti-aging agents, activators, process oils, plasticizers, lubricants, and tackifiers, respectively. Can be mixed in the required amount. The contents of such other components and their contents can be, for example, the same as those described in JP-A-2016-30795.

The other components may include fillers other than silica. As the filler other than silica, those generally used for rubber compositions can be used, for example, carbon black, clay, diatomaceous earth, talc, barium sulfate, calcium carbonate, magnesium carbonate, metal oxide, mica. , Aluminum hydroxide, various metal powders, wood powders, glass powders, ceramic powders, etc., as well as inorganic hollow fillers such as glass balloons, silica balloons; organic hollows made of polystyrene, polyvinylidene fluoride, polyvinylidene fluoride copolymers, etc. Fillers and the like can be mentioned. Among these fillers, for example, carbon black and the like described in JP-A-2016-30795 can be used.

In the present invention, the filler is preferably carbon black or the like. This is because the rubber composition has excellent wet grip properties due to the filler.

Further, the filler may contain at least one type, may contain only one type, or may be used as a mixture of two or more types.

The content of the filler other than silica may be any as long as it can obtain a rubber composition having excellent processability and an excellent balance between rolling resistance and wet grip performance. The content may be, for example, 120 parts by mass or less in proportion to 100 parts by mass of diene-based rubber.

E. Rubber Composition In the method for producing a rubber composition of the present invention, each component may be kneaded according to a conventional method. For example, a component excluding heat-unstable components such as a cross-linking agent and a cross-linking accelerator and a diene-based rubber are used. After kneading, a heat-unstable component such as a cross-linking agent or a cross-linking accelerator can be mixed with the kneaded product to obtain a desired composition. The kneading temperature of the component excluding the heat-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 in the range of 80 ° C. to 200 ° C. Is 30 seconds to 30 minutes. Further, the kneaded product and the heat-unstable component are usually mixed after cooling to 100 ° C. or lower, preferably 80 ° C. or lower.

As a cross-linking method using the rubber composition of the present invention as a rubber cross-linked product, a known cross-linking method can be used. Examples thereof include a method of molding with a roll or the like, performing a cross-linking reaction by heating, and fixing the shape as a cross-linked product. In this case, even if the cross-linking is performed after molding in advance, the cross-linking can be performed at the same time as the 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. It is within the range of, particularly preferably within the range of 3 minutes to 6 hours.

Further, depending on the shape and size of the rubber crosslinked product, even if the surface is crosslinked, it may not be sufficiently crosslinked to the inside. good.

As the heating method, a general method used for crosslinking the rubber composition such as press heating, steam heating, oven heating, and hot air heating 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 makes use of such characteristics, and is preferably used as a material for each part of the tire such as a tread (cap tread, base tread), carcass, sidewall, and bead portion of the tire. In particular, in various tires such as all-season tires, high-performance tires, and studless tires, it can be suitably used for each part of the tire such as tread, carcass, sidewall, and bead part, and is particularly excellent in low heat generation. Therefore, it can be particularly preferably used for treads of fuel-efficient tires, and particularly preferably for cap treads.

II. Pneumatic tire Next, the pneumatic tire of the present invention will be described. The pneumatic tire of the present invention is characterized in that the above-mentioned rubber composition is used for a tread.

The tread uses the above-mentioned rubber composition, that is, is formed by using the above-mentioned rubber composition, and usually contains a crosslinked product of the above-mentioned rubber composition.

The rubber composition and the crosslinked product thereof used for forming such a tread can be the same as those described in the above section "I. Rubber composition", and thus the description thereof is omitted here.

The pneumatic tire may have a tread formed by using the rubber composition, and other portions may be formed by using the rubber composition.

The tread formed by using the above rubber composition may be a part of the tread or the whole tread, but preferably contains at least a cap tread.

Further, as the method for manufacturing a pneumatic tire of the present invention, any method can be used as long as it can manufacture a pneumatic tire having a tread formed by using the above composition, and a known method for manufacturing a pneumatic tire can be used. can.

The present invention is not limited to the above embodiment. The above embodiment is an example, and any one having substantially the same structure as the technical idea described in the claims of the present invention and having the same effect and effect is the present invention. It is included in the technical scope of the invention.

Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples. Unless otherwise specified, parts and% in each example are based on mass.

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 sample hydrocarbon resin is analyzed by gel permeation chromatography to obtain the number average molecular weight (Mn), weight average molecular weight (Mw) and Z average molecular weight (Mz) of standard polystyrene conversion values, and the molecular weight distribution is Mw. It is shown by the ratio of / Mn and the ratio of Mz / Mw. For gel permeation chromatography analysis, Tosoh's "HLC-8320GPC" was used as the measuring device, and Tosoh's "TSKgel SuperMultipore HZ" was used as the column, and tetrahydrofuran was used as the solvent. , 40 ° C., measured at a flow rate of 1.0 mL / min.

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

[Mixed aniline point (° C)]
The hydrocarbon resin used 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 under the following conditions according to JIS K 630-1: 2001. This characteristic is shown by an index with the reference sample (Comparative Example 1 described later) as 100.
-Test temperature: 100 ° C
・ Rotor type: L type ・ Test machine used: Shimadzu Mooney Viscometer SMV-300J manufactured by Shimadzu Corporation

[Tensile strength (MPa) and elongation (%)]
The tensile strength (tensile stress (MPa)) and elongation (elongation (%)) of the test piece of the rubber crosslinked product as a sample were measured under the following conditions according to JIS K 6251: 2010. These characteristics are shown by an index with the reference sample (Comparative Example 1 described later) as 100.
・ Test piece preparation method: After sheet preparation by press vulcanization, punching processing ・ Test piece shape: Dumbbell-shaped No. 3 type ・ Test piece collection direction: Parallel to the column ・ Number of test pieces: 3
・ Measurement temperature: 23 ° C
・ Test speed: 500 mm / min
-Testing machine used: TENCOMETER 10k manufactured by ALPHA TECHNOLOGIES
・ Testing machine capacity: Load cell type 1kN

[Loss tangent tan δ]
For the test piece of the rubber cross-linked product as a sample, the loss tangent tan δ at 0 ° C. and 60 ° C. was measured under the following measurement conditions under the conditions of dynamic strain 0.5% and 10 Hz according to JIS K 7244-4. .. This characteristic is shown by an index with the reference sample (Comparative Example 1 described later) as 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 modulus E'
: Dynamic loss elastic modulus E''
: Loss tangent tanδ
-Sample preparation method: Punching from the sheet-Test piece shape: Length 50 mm x Width 2 mm x Thickness 2 mm
・ Number of test pieces: 1
・ Distance between clamps: 20 mm

[Manufacturing Example 1]
A mixture of 56.1 parts of cyclopentane and 15.5 parts of cyclopentene was charged into the polymerization reactor, the temperature was raised to 70 ° C., and then 0.75 parts of aluminum chloride was added (mixture M ₁ ). Subsequently, 1,3-pentadiene 46.7 parts, isobutylene 18.4 parts, diisobutylene 0.1 parts, dicyclopentadiene 0.1 parts, C4-C6 unsaturated hydrocarbon 0.2 parts, C4-C6 saturated hydrocarbons. _A mixture a1 consisting of 7.2 parts of hydrogen and 19.0 parts of aromatic monoolefin was continuously added to the polymerization reactor containing the mixture M1 while maintaining the temperature ( ₇₀ ° C.) for 60 minutes. While polymerizing, it was carried out. Then, an aqueous sodium hydroxide solution was added to the polymerization reactor to terminate 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 produced by the polymerization termination by filtration, the obtained polymer solution was placed in a distillation pot and heated under a nitrogen atmosphere to remove the polymerization solvent and the unreacted monomer. Then, at 240 ° C. or higher, the low molecular weight oligomer component was distilled off while blowing saturated steam to obtain the hydrocarbon resin of Production Example 1. For the obtained hydrocarbon resin of Production Example 1, the number average molecular weight, the weight average molecular weight, the Z average molecular weight, the molecular weight distribution, the softening point and the mixed aniline point were measured. The results of these measurements are summarized in Table 1 below.

_The aromatic monoolefin contained in the mixture a1 is contained as an aromatic monomer. As the 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.

[Manufacturing Examples 2 to 6]
A hydrocarbon resin was obtained in the same manner as in Production Example 1 except that the types and amounts of the components to be added to the polymerization reactor were changed as shown in Table 1 below. As for the obtained hydrocarbon resins of Production Examples 2 to 6, the number average molecular weight, the weight average molecular weight, the Z average molecular weight, the molecular weight distribution, the softening point and the mixed aniline point were measured in the same manner as in the hydrocarbon resin of Production Example 1. .. The results of these measurements are summarized in Table 1 below.

In Production Examples 2 to 6, styrene is used as the aromatic monomer other than the monomer having a structure in which two or more cyclic structures are bonded, as in Production Example 1. Further, in Production Example 4, the aromatic monomer is not contained.

[Example 1]
Oil-expanded emulsified polymerized styrene-butadiene rubber (E-SBR) (trade name "Nipol1739", manufactured by Nippon Zeon Co., Ltd., molecular weight of bonded styrene: 40%, vinyl bond content of butadiene unit portion: 13. 5 mol%, weight average molecular weight: 690,000, molecular weight distribution (Mw / Mn): 3.98, glass transition temperature (Tg): -35 ° C., 37.5 parts of stretched oil per 100 parts of rubber component. Content) 96.3 parts (rubber component content: 70 parts, spreading oil content: 26.3 parts) and solution-polymerized styrene-butadiene rubber (S-SBR) (trade name "Nipol NS 616", Nippon Zeon Co., Ltd., Mooney viscosity (ML1 + 4,100 ° C.): 62) 15.0 parts and natural rubber (NR) (SIR20) 15.0 parts are kneaded for 30 seconds, and then silica (manufactured by Rhodia, trade name). "Zeosil1165MP") 60.0 parts, carbon black (manufactured by Cabot Japan Co., Ltd., trade name "N234") 20.0 parts, silane coupling agent: bis [3- (triethoxysilyl) propyl] tetrasulfide ( 9.0 parts of (trade name "Si69") manufactured by Degussa and 10.0 parts of the hydrocarbon resin obtained in Production Example 1 are added and kneaded for 90 seconds, and then silica (manufactured by Rhodia, trade name "Zeosil1165MP"). 40.0 parts, zinc oxide 3.0 parts, stearate 2.0 parts and anti-aging agent: N-phenyl-N'-(1,3-dimethylbutyl) -p-phenylenediamine (manufactured by Ouchi Shinko Co., Ltd., 2.0 parts of product name "Nocrack 6C") was added, and the mixture was further kneaded for 90 seconds, and then 15.0 parts of process oil (manufactured by Shin Nihon Petroleum Co., Ltd., product name "Aromax T-DAE") was added. Then, the mixture was kneaded at 90 ° C. as a starting temperature, kneaded at 145 ° C. to 155 ° C. for 60 seconds or longer (primary kneading), and then the kneaded material was discharged from the mixer.

The obtained kneaded product was cooled to room temperature, kneaded again in a Banbury type mixer for 2 minutes at a starting temperature of 90 ° C. (secondary kneading), 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, in two rolls at 50 ° C., 1.7 parts of sulfur was added to the obtained kneaded product, and the vulcanization accelerator: N-cyclohexyl-2-benzothiazolyl sulfenamide (CBS trade name "Noxeller CZ-G"). , 1.8 parts manufactured by Ouchi Shinko Kagaku Kogyo Co., Ltd., and 1.7 parts of diphenylguanidine (DPG trade name "Noxeller D", manufactured by Ouchi Shinko Kagaku Kogyo Co., Ltd.) and kneaded (mixed with vulcanizing agent). After kneading), the sheet-shaped rubber composition was taken out.

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

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

(Kneading conditions for vulcanizing agent kneading)
・ Testing machine: Electric heating type high temperature roll machine manufactured by Ikeda Kikai Kogyo Co., Ltd. ・ Roll size: 6φ × 16
・ Front roll rotation speed: 24 rpm
・ Front-back roll rotation ratio: 1: 1.22
・ Roll temperature: 50 ℃ ± 5 ℃
・ Number of turns: 2 times on each side ・ Rounding width: Roll spacing approx. 0.8 mm
・ Number of rounding: 5 times

[Examples 2 to 3 and Comparative Examples 1 to 3]
As shown in Table 2 below, a rubber composition was obtained in the same manner as in Example 1 except that the hydrocarbon resin obtained in Production Examples 2 to 6 was used instead of the hydrocarbon resin obtained in Production Example 1. ..

〔evaluation〕
The rubber compositions obtained in 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 constant temperature room at 23 ° C., and then 150 mm × 150 mm × thickness. A test piece of a 2 mm rubber crosslinked product was prepared.

For the rubber composition and the rubber crosslinked product 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 crosslinked product were measured. The results are shown in Table 2 below.

From Tables 1 and 2, it was confirmed that in the examples, the loss tangent tan δ at 0 ° C. was high and the loss tangent tan δ at 60 ° C. was low. From this result, it was confirmed that both rolling resistance and wet grip performance were excellent.

Further, when the diene-based rubber and the hydrocarbon resin are contained, the rubber composition is excellent in both rolling resistance and wet grip performance, so that the rubber composition is excellent in compatibility and workability. I was able to confirm that it would be. Further, it was confirmed that even when the rubber composition contains silica, the dispersibility of silica is good and the processability is excellent.

That is, from Tables 1 and 2, those containing a monomer unit having a structure in which two or more cyclic structures are bonded in a predetermined ratio, and having characteristics such as a predetermined weight average molecular weight (Mw) and a softening point. In particular, for example, a hydrocarbon resin having a moderately low weight average molecular weight (Mw) and a ratio (Mw / Mn) of a weight average molecular weight to a number average molecular weight (Mn) and a moderately high softening point is used together with silica for a diene rubber. It was confirmed that the rubber composition was excellent in workability and excellent in both rolling resistance and wet grip performance by containing a predetermined amount of the rubber composition.

Claims (5)

For 100 parts by mass of diene rubber
A rubber composition comprising 1 part by mass to 30 parts by mass of a hydrocarbon resin and 80 parts by mass to 200 parts by mass of silica.
The hydrocarbon resin is
Includes aliphatic monomer units and aromatic monomer units
Among the aromatic monomer units, the content of the monomer unit having a structure in which two or more cyclic structures are bonded is 50% by mass or more in the aromatic monomer unit.
A rubber composition having a weight average molecular weight (Mw) in the range of 700 to 6000 and a softening point in the range of 80 ° C. to 150 ° C. The hydrocarbon resin
1,3-Pentidiene monomer unit 10% by mass to 60% by mass,
Alicyclic monoolefin monomer unit with 4 to 6 carbon atoms 1% by mass to 30% by mass,
Acyclic monoolefin monomer unit having 4 to 8 carbon atoms 1% by mass to 50% by mass,
It contains 0% by mass to 10% by mass of an 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, and 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.
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 (Mz / Mw) of the Z average molecular weight to the weight average molecular weight is 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 a naphthalene compound, a fluorene compound, a biphenyl compound, an anthracene compound, a phenanthrene compound, an inden compound and a benzothiophene compound. The rubber composition according to claim 1 or 2, wherein the rubber composition is characterized by the above. The value of the mixed aniline point measured at the lowest temperature at which the hydrocarbon resin is present as a uniform solution of aniline, methylcyclohexane and the hydrocarbon resin (volume ratio 2: 1: 1) is 25 ° C to 100. The rubber composition according to any one of claims 1 to 3, wherein the temperature is within the range of ° C. A pneumatic tire using the rubber composition according to any one of claims 1 to 4 for a tread.