WO2024219257A1 - Rubber composition - Google Patents

Abstract

Provided is a rubber composition which is excellent in terms of the balance among wet grip properties, rolling resistance and abrasion resistance, especially in terms of abrasion resistance and ice grip properties.　The rubber composition contains a diene-based rubber and an aliphatic-aromatic-DCPD copolymerized petroleum resin. The rubber composition contains 5-40 parts by mass inclusive of the aliphatic-aromatic-DCPD copolymerized petroleum resin per 100 parts by mass of the diene-based rubber. The diene-based rubber contains more than 50 mass% of a styrene-butadiene copolymer rubber and/or a natural rubber. The aliphatic-aromatic-DCPD copolymerized petroleum resin satisfies all of the following characteristics (1) to (5): (1) (i) having an aliphatic hydrogen ratio of more than 85% and not more than 89%, (ii) having a DCPD double-bond hydrogen ratio of 7-10% inclusive, and (iii) having an aromatic hydrogen ratio of 1-8% inclusive; (2) having Mw of 2,000-3,000 inclusive and Mw/Mn of 2.0-3.0 inclusive; (3) having a bromine value of 45-60 inclusive; (4) having a softening point of 85-115°C inclusive; and (5) having a Gardner color value of 5-10 inclusive.

Description

Rubber composition

The present invention relates to a new rubber composition that has an excellent balance of wet grip, rolling resistance, and abrasion resistance, as well as ice grip, and is particularly suitable for use in tires.

In recent years, with the increasing performance and functionality of automobiles, there has been an increasing demand for tires with improved performance. For example, there is a demand for tires with improved wet grip, rolling resistance, and abrasion resistance, which are mutually exclusive. In addition, electric vehicles and plug-in hybrid vehicles equipped with drive batteries are subject to increased loads on the tires as the vehicle weight increases, so tires with improved durability are required. Technologies that incorporate silica into rubber to improve rolling resistance and technologies that use modified rubber with terminals that have functional groups at the terminals that have high affinity with silica or can be chemically bonded to silica to increase the dispersibility of silica are being used.

For the purpose of improving the mechanical properties of tires and imparting good adhesion to unvulcanized rubber compositions, it has been proposed to compound an aliphatic/aromatic copolymer resin (see, for example, Patent Document 1) or an aliphatic/alicyclic copolymer resin (see, for example, Patent Document 2) with rubber.
Furthermore, for the purpose of achieving high braking performance on both dry and wet road surfaces, it has been proposed to compound a thermoplastic resin such as a C5 resin, a C5/C9 resin, or a C9 resin with a rubber component containing 70% by mass or more of natural rubber (see, for example, Patent Document 3). Also proposed are a rubber composition containing an aliphatic-aromatic-dicyclopentadiene copolymer petroleum resin (see, for example, Patent Document 4), and a new C5-dicyclopentadiene copolymer resin and a rubber composition containing the same (see, for example, Patent Document 5).

Japanese Patent No. 5309529 Japanese Patent No. 5375101 Japanese Patent No. 6346325 Japanese Patent Application Publication No. 2020-203962 Japanese Patent Application Publication No. 2022-55449

However, the methods proposed in Patent Documents 1 and 2 propose the blending of carbon black as the main filler, and do not consider wet grip properties, rolling resistance, abrasion resistance, or the balance thereof, and there is room for improvement, particularly in terms of tire composition performance. In addition, the rubber composition proposed in Patent Document 3 does not consider aliphatic-aromatic-dicyclopentadiene copolymer petroleum resin or C5-dicyclopentadiene copolymer resin, and no proposal is made regarding their effects. Furthermore, the proposals in Patent Documents 4 and 5 provide rubber compositions containing aliphatic-aromatic-dicyclopentadiene copolymer petroleum resin and a new C5-dicyclopentadiene copolymer resin, and although some effect is seen in the balance of wet grip properties, rolling resistance, and abrasion resistance, there is room for improvement, particularly in terms of abrasion resistance.

The present invention therefore aims to provide a new rubber composition that contains a specific aliphatic-aromatic-dicyclopentadiene copolymer petroleum resin and has an excellent balance of wet grip, rolling resistance, and abrasion resistance, and is particularly excellent in abrasion resistance and ice grip.

The inventors conducted extensive research to solve the above problems and discovered that a rubber composition containing a specific diene rubber and a specific aliphatic-aromatic-dicyclopentadiene copolymer petroleum resin exhibits excellent rubber properties, leading to the completion of the present invention.

That is, the present invention resides in the following [1] to [6].
[1] A rubber composition comprising a diene rubber and an aliphatic-aromatic-dicyclopentadiene copolymer petroleum resin which is a copolymer resin of a C5 fraction, dicyclopentadienes, and a C9 fraction of petroleum, the rubber composition comprising 5 to 40 parts by mass of the aliphatic-aromatic-dicyclopentadiene copolymer petroleum resin which is a copolymer resin of a C5 fraction, dicyclopentadienes, and a C9 fraction of petroleum per 100 parts by mass of the diene rubber, the diene rubber comprising more than 50% by mass of a styrene-butadiene copolymer rubber and/or a natural rubber, and the aliphatic-aromatic-dicyclopentadiene copolymer petroleum resin satisfying any of the following properties (1) to (5).
(1) As measured by proton NMR, (i) the ratio of aliphatic hydrogen derived from aliphatic components observed at 0.2 to 4.0 ppm is more than 85% and not more than 89%, (ii) the ratio of dicyclopentadiene double bond hydrogen derived from double bonds of dicyclopentadiene components observed at 4.4 to 6.3 ppm is 7% or more and 10% or less, and (iii) the ratio of aromatic hydrogen derived from aromatic components observed at 6.3 to 7.6 ppm is 1% or more and not more than 8%.
(2) The weight average molecular weight measured by gel permeation chromatography in accordance with JIS K-0124 (2011) using standard polystyrene as the standard substance is 2,000 or more and 3,000 or less, and the weight average molecular weight/number average molecular weight is 2.0 or more and 3.0 or less.
(3) The bromine number measured in accordance with JIS K-2605 (1996) is 45 g-Br2/100 g or more and 60 g-Br2/100 g or less.
(4) The softening point measured in accordance with JIS K-2207 (1996) (ring and ball method) is 85° C. or higher and 115° C. or lower.
(5) The Gardner hue of a 50% by mass solution in toluene, as measured in accordance with ASTM D-1544-63T, is 5 or greater and 10 or less.
[2] The rubber composition according to [1], wherein the styrene-butadiene copolymer rubber has a styrene content of 25 mass% or less.
[3] The rubber composition according to [1] or [2], characterized in that the diene rubber is a mixed diene rubber of a styrene-butadiene copolymer rubber and at least one rubber selected from the group consisting of isoprene rubber, natural rubber, and butadiene rubber.
[4] The rubber composition according to any one of [1] to [3], wherein the diene rubber is a mixed diene rubber of a styrene-butadiene copolymer rubber and a natural rubber.
[5] The rubber composition according to any one of [1] to [4], which is a vulcanized rubber composition constituting a tire.
[6] A tire having a tread made of the rubber composition according to [5].

The present invention provides a rubber composition and a tire using the same that has an excellent balance of wet grip, rolling resistance, and abrasion resistance, as well as excellent ice grip, and is extremely useful industrially.

The present invention will be described in detail below.
The rubber composition of the present invention has, per 100 parts by mass of a diene rubber containing more than 50% by mass of styrene-butadiene copolymer rubber and/or natural rubber, (1) a ratio of aliphatic hydrogen derived from an aliphatic component observed at 0.2 to 4.0 ppm is more than 85% and not more than 89%, (ii) a ratio of dicyclopentadiene double bond hydrogen derived from a double bond of a dicyclopentadiene component observed at 4.4 to 6.3 ppm is 7% or more and 10% or less, and (iii) a ratio of aromatic hydrogen derived from an aromatic component observed at 6.3 to 7.6 ppm is 1% or more and not more than 8% as measured by proton NMR. The rubber composition includes 5 parts by mass or more and 40 parts by mass or less of an aliphatic-aromatic-dicyclopentadiene copolymer petroleum resin, which is a copolymer resin of a C5 fraction, a dicyclopentadienes, and a C9 fraction of petroleum, and which satisfies the following: (2) a weight average molecular weight (hereinafter sometimes referred to as Mw) of 2,000 or more and 3,000 or less, a weight average molecular weight/number average molecular weight (hereinafter sometimes referred to as Mw/Mn) of 2.0 or more and 3.0 or less, (3) a bromine number of 45 g-Br2/100 g or more and 60 g-Br2/100 g or less, (4) a softening point of 85° C. or more and 115° C. or less, and (5) a Gardner hue of 5 or more and 10 or less.

The diene rubber constituting the rubber composition of the present invention is one containing more than 50% by mass of styrene-butadiene copolymer rubber and/or natural rubber, preferably 52% by mass or more, and preferably 55% by mass or more. Examples of the styrene-butadiene copolymer rubber include styrene-butadiene random copolymer rubber, styrene-butadiene block copolymer rubber, styrene-butadiene-styrene triblock copolymer rubber, and hydrogenated products thereof. In particular, since the rubber composition has an excellent balance of wet grip properties, abrasion resistance, and ice grip properties, it is preferable to use styrene-butadiene copolymer rubber having a styrene content of 25% by mass or less, and more preferably the styrene content is 10% by mass or less. In addition, an example of the natural rubber is RSS#3. Here, if the total content of the styrene-butadiene copolymer rubber and the natural rubber is 50% by mass or less, the resulting composition will have poor compatibility, processability, and ice grip properties.

The diene rubber may contain components other than styrene-butadiene copolymer rubber and natural rubber, for example, isoprene rubber, butadiene rubber, ethylene propylene diene rubber, butyl rubber, halogenated butyl rubber, acrylonitrile butadiene rubber, chloroprene rubber, silicone rubber, olefin elastomer (TPO), urethane elastomer (TPU), polyester elastomer (TPEE), polyamide elastomer (TPA), polybutadiene elastomer (RB), polyvinyl chloride (PVC), ethylene / vinyl acetate copolymer (EVA), etc. Among them, isoprene rubber, butadiene rubber, butyl rubber, and further isoprene rubber are preferably blended because they are rubber compositions excellent in balance of wet grip properties, rolling resistance, abrasion resistance, processability, and ice grip properties.
From the viewpoint of achieving an excellent balance of tire performance, the diene rubber is preferably a mixed diene rubber of a styrene-butadiene copolymer rubber and at least one rubber selected from the group consisting of isoprene rubber, natural rubber, and butadiene rubber, and more preferably a mixed diene rubber of a styrene-butadiene copolymer rubber and natural rubber.

There are no particular limitations on the manufacturing method of diene rubbers other than natural rubber, and they may be anionic polymerized products or emulsion polymerized products. In addition, there are no particular limitations on the molecular weight or microstructure of the diene rubber, and they may be terminally modified with amine, amide, silyl, alkoxysilyl, carboxyl, hydroxyl groups, etc., or may be epoxidized.

The aliphatic-aromatic-dicyclopentadiene copolymer petroleum resin constituting the rubber composition of the present invention is a petroleum resin obtained by copolymerizing a C5 fraction, which is an aliphatic fraction obtained by separating and refining petroleum, a C9 fraction, which is an aromatic fraction, and a dicyclopentadiene (hereinafter sometimes referred to as DCPD) fraction, and among these, (1) as measured by proton NMR, (i) the aliphatic hydrogen ratio is more than 85% and not more than 89%, (ii) the dicyclopentadiene The aliphatic-aromatic-dicyclopentadiene copolymerized petroleum resin satisfies the following: (i) ene double bond hydrogen ratio is 7% or more and 10% or less, (ii) aromatic hydrogen ratio is 1% or more and 8% or less, (iii) Mw is 2,000 or more and 3,000 or less, Mw/Mn is 2.0 or more and 3.0 or less, (3) bromine number is 45 g-Br2/100 g or more and 60 g-Br2/100 g or less, (4) softening point is 85°C or more and 115°C or less, and (5) Gardner hue is 5 or more and 10 or less. The aliphatic-aromatic-dicyclopentadiene copolymerized petroleum resin is a petroleum resin composed of copolymerized components of an aliphatic component which is a polymerization residue unit derived from a C5 fraction, an aromatic component which is a polymerization residue unit derived from a C9 fraction, and a DCPD component which is a DCPD residue unit derived from a dicyclopentadiene fraction.

The components constituting the aliphatic component include, for example, aliphatic compounds having 4 carbon atoms, such as butene, butadiene, and isobutene; linear aliphatic compounds having 5 carbon atoms, such as 2-methyl-1-butene, 3-methyl-1-butene, 2-methyl-2-butene, isoprene, and piperylene; cyclic aliphatic compounds having 5 carbon atoms, such as cyclopentadiene; 1-hexene, 2-hexene, 3-hexene, 2-methyl-1-pentene, 3-methyl-1-pentene, 4-methyl-1-pentene, 2-methyl-2-pentene, 3-methyl-2-pentene, 4-methyl-2-pentene, 2-ethyl-1-butene, 2-ethyl-2-but ... Examples of such compounds include linear aliphatic compounds having 6 carbon atoms, such as 1-heptene, 2-heptene, 3-heptene, 2-methyl-3-hexene, 4-methyl-2-hexene, and 3,4-dimethyl-2-pentene; linear aliphatic compounds having 7 carbon atoms, such as 1-heptene, 2-heptene, 3-heptene, 2-methyl-3-hexene, 4-methyl-2-hexene, and 3,4-dimethyl-2-pentene; mixtures of these compounds, and components based on mixtures called C5 fractions. Components based on linear aliphatic compounds having 4 to 6 carbon atoms are particularly easy to obtain and have excellent performance as tackifiers.

The components constituting the aromatic component include, for example, aromatic compounds with 8 carbon atoms such as styrene; aromatic compounds with 9 carbon atoms such as α-methylstyrene, β-methylstyrene, vinyltoluene, and indene; aromatic compounds with 10 carbon atoms such as 1-methylindene, 2-methylindene, and 3-methylindene; aromatic compounds with 11 carbon atoms such as 2,3-dimethylindene and 2,5-dimethylindene; mixtures of these, and components based on mixtures known as C9 fractions. Components based on aromatic compounds with 8 to 10 carbon atoms are particularly easy to obtain and have excellent performance as tackifiers.

　Components constituting DCPD-type components include, for example, cyclic aliphatic compounds having 10 carbon atoms, such as dicyclopentadiene; cyclic aliphatic compounds having 11 carbon atoms, such as methyldicyclopentadiene; cyclic aliphatic compounds having 12 carbon atoms, such as dimethyldicyclopentadiene; mixtures of these, and components based on mixtures called dicyclopentadiene fractions. In particular, components based on dicyclopentadiene compounds having 10 to 12 carbon atoms are easy to obtain and have excellent performance as tackifiers.

The aliphatic-aromatic-dicyclopentadiene copolymer petroleum resin is (1) an aliphatic-aromatic-dicyclopentadiene copolymer petroleum resin having (i) an aliphatic hydrogen ratio derived from an aliphatic polymerization residue unit of more than 85% and not more than 89%, (ii) a DCPD double bond hydrogen ratio derived from a DCPD residue unit of 7% or more and not more than 10%, and (iii) an aromatic hydrogen ratio derived from an aromatic polymerization residue unit of 1% or more and not more than 8%, and each hydrogen ratio can be measured under the following conditions (A) to (C) based on the area percentage of a spectrum measured and observed by proton NMR using chloroform-d as a solvent.
(a) It is determined from the area ratio of hydrogen derived from aliphatic components observed between 0.2 and 4.0 ppm.
(a) It is determined from the area ratio of hydrogen derived from the double bonds of DCPD components observed at 4.4 to 6.3 ppm.
(c) Determined from the area ratio of hydrogen derived from aromatic components observed between 6.3 and 7.6 ppm.

An aliphatic-aromatic-dicyclopentadiene copolymer petroleum resin that satisfies all of the above requirements (i) to (iii) has excellent compatibility with diene rubbers.
The aliphatic-aromatic-dicyclopentadiene copolymerized petroleum resin (2) has an Mw/Mn of 2.0 or more and 3.0 or less, as measured by GPC in accordance with JIS K-0124 (1994) using standard polystyrene as the standard substance. If the Mw/Mn is less than 2.0 or exceeds 3.0, the rubber composition will have poor mixability (compatibility), and the tire will have poor performance. In addition, the rubber composition will have excellent processability, so the Mw is 2,000 or more and 3,000 or less.

Furthermore, the aliphatic-aromatic-dicyclopentadiene copolymer petroleum resin satisfies all of the following characteristics: (3) a bromine number measured in accordance with JIS K-2605 (1996) of 45 g-Br2/100 g or more and 60 g-Br2/100 g or less, (4) a softening point measured in accordance with JIS K-2207 (1996) (ring and ball method) of 85°C or more and 115°C or less, and (5) a Gardner hue measured in accordance with ASTM D-1544-63T as a 50% by mass toluene solution of 5 or more and 10 or less.

The aliphatic-aromatic-dicyclopentadiene copolymer petroleum resin satisfies all of the characteristics (1) to (5), and therefore not only has excellent compatibility with diene rubbers, and further with diene rubbers containing more than 50 mass% of styrene-butadiene copolymer rubber and/or natural rubber, but also makes it possible to provide a rubber composition that has an excellent balance of wet grip properties, rolling resistance, abrasion resistance, and ice grip properties.

There is no particular restriction on the method for producing the aliphatic-aromatic-dicyclopentadiene copolymer petroleum resin, and any method may be used. For example, the resin can be produced by using a mixture obtained by thermal decomposition of petroleum, which contains a fraction having a boiling point range of 20°C to 110°C (C5 fraction; aliphatic components), a fraction having a boiling point range of 140°C to 280°C (C9 fraction; aromatic components), and a dicyclopentadiene fraction, as a raw material oil, adding a catalyst to the mixture, and polymerizing by heating. There is no particular restriction on the catalyst used in the polymerization, and examples of the catalyst include aluminum trichloride, aluminum tribromide, boron trifluoride, and complexes thereof. Among these, alcohol and phenol complexes of boron trifluoride, such as methanol, propanol, butanol, isobutanol, isopentanol, and phenol, are selected because of their excellent catalytic activity. Among these, butanol complexes, isobutanol complexes, and isopentanol complexes are more preferable, and boron trifluoride butanol complexes are particularly preferable. The complex may be used as is or may be prepared in-suit from boron trifluoride, alcohols, and phenols immediately before use. Examples of the solvent during polymerization include saturated hydrocarbons in the C5 fraction and C9 fraction. The feedstock oil is preferably a mixture of 35% to 45% by mass of an aliphatic component, 5% to 15% by mass of an aromatic component, and 45% to 55% by mass of a DCPD component, since this produces an aliphatic-aromatic-dicyclopentadiene copolymerized petroleum resin with particularly excellent softening point and color.

The polymerization temperature during production is not particularly limited, and is preferably 20°C to 80°C, particularly 30°C to 60°C, since it provides high polymerization activity and excellent productivity. The amount of catalyst and polymerization time can be appropriately selected depending on the temperature and the water concentration in the raw oil, and typically, for example, the catalyst is 0.1% by mass to 2.0% by mass relative to the raw oil, and the polymerization time is 0.1 hours to 10 hours. The reaction pressure is also not particularly limited, and is preferably atmospheric pressure or higher and 1 MPa or lower. The atmosphere is also not particularly limited, and a nitrogen atmosphere is particularly preferred.
The rubber composition of the present invention contains 5 parts by mass or more and 40 parts by mass or less, preferably 8 parts by mass or more and 30 parts by mass or less, of the aliphatic-aromatic-dicyclopentadiene copolymer petroleum resin per 100 parts by mass of the diene rubber. If the aliphatic-aromatic-dicyclopentadiene copolymer petroleum resin is less than 5 parts by mass, the resulting composition will be inferior in wet grip properties and abrasion resistance. On the other hand, if the aliphatic-aromatic-dicyclopentadiene copolymer petroleum resin is more than 40 parts by mass, the resulting composition will be inferior in rolling resistance and ice grip properties.

In addition, the rubber composition of the present invention preferably contains 5 to 200 parts by mass of silica per 100 parts by mass of diene rubber, more preferably 10 to 150 parts by mass, and even more preferably 20 to 120 parts by mass. The silica in this case is not particularly limited, and those used in commercially available rubber compositions can be used, among which wet silica (hydrated silica), dry silica (anhydrous silicic acid), colloidal silica, etc. can be used, and wet silica is particularly preferred. In particular, a rubber composition containing an aliphatic-aromatic-dicyclopentadiene copolymerized petroleum resin can reduce viscosity, so that even if the rubber composition contains a high content of silica such as 70 parts by mass or more, it is a rubber composition that can provide a tire that is excellent in processability and has an excellent balance of wet grip properties, rolling resistance, and abrasion resistance.

When using silica, it is preferable to use a silane coupling agent in combination. By using a silane coupling agent in combination, the bond between the rubber component and the silica is strengthened via the silane coupling agent, making it possible to highly improve the balance of wet grip properties, rolling resistance, and abrasion resistance. Examples of silane coupling agents include sulfide-based, mercapto-based, vinyl-based, amino-based, glycidoxy-based, nitro-based, and chloro-based silane coupling agents. These silane coupling agents can be used alone or in combination of two or more types.

In the rubber composition of the present invention, in addition to the silica, a reinforcing filler such as carbon black can be used in combination. The carbon black may be of grades such as FEF, SRF, HAF, ISAF, or SAF. The carbon black content is preferably 10 parts by mass or more and 60 parts by mass or less per 100 parts by mass of diene rubber, since this provides excellent rolling resistance.

The rubber composition of the present invention may further contain additives that are usually compounded into resin compositions and rubber compositions. For example, compounding agents such as crosslinking agents such as sulfur, vulcanization accelerators, vulcanization accelerator assistants, stearic acid, zinc oxide, plasticizers, oils, and antioxidants may be added. Commercially available products can be suitably used as these compounding agents.

The rubber composition of the present invention may contain additives that are usually blended into resin compositions and rubber compositions, such as a phenol-based antioxidant, a phosphorus-based antioxidant, a sulfur-based antioxidant, a lactone-based antioxidant, an ultraviolet absorber, a pigment, calcium carbonate, glass beads, etc., as long as the blended additives do not deviate from the object of the present invention.
Furthermore, the rubber composition of the present invention also includes its form and shape, and may be a crosslinked product (vulcanizate) that has been crosslinked (vulcanized) by containing a crosslinking agent, a vulcanization accelerator, a vulcanization acceleration assistant, etc.

The rubber composition of the present invention can be produced by blending diene rubber, aliphatic-aromatic-dicyclopentadiene copolymer petroleum resin, and various compounding agents selected as necessary, using a mixing method such as a Banbury mixer, a pressure kneader, or an open roll. Furthermore, the resulting unvulcanized rubber composition can be crosslinked using, for example, a calendar, a roll, an extruder, or a press to produce a vulcanized rubber composition.

The present invention can provide a rubber composition that has excellent wet grip properties, abrasion resistance, and processability, and can be used in a variety of rubber applications, such as rolls, mats, tubes, grips, and handles. It can also provide excellent tire components, particularly treads, tires having the same, and further studless tires, all-season tires, and tires for electric vehicles.

The present invention will be described below with reference to examples, but the present invention is not limited to these examples. The analytical and test methods used in the examples and comparative examples are as follows.

The analytical method for aliphatic-aromatic-dicyclopentadiene copolymer petroleum resin is shown below.
[Proton NMR (Nuclear Magnetic Resonance Spectroscopy) Measurement]
The copolymerized petroleum resin was dissolved in chloroform-d (manufactured by Wako Pure Chemical Industries, Ltd.) and measured by a conventional NMR measurement method. For the spectrum obtained, the hydrogen ratio was calculated from the area ratio based on the following calculation formula.
Area ratio (%) = (each peak area) / (total of all peak areas) x 100
The peaks are assigned as follows:
Aliphatic hydrogen peak: 0.2 to 4.0 ppm.
DCPD double bond hydrogen peak: 4.4 to 6.3 ppm.
Aromatic hydrogen peak: 6.3-7.6 ppm.

[Measurement of weight average molecular weight (Mw) and number average molecular weight (Mw)]
Polystyrene was used as the standard substance and the measurement was performed by gel permeation chromatography in accordance with JIS K-0124 (2011).
[Bromine number]
The measurement was performed according to a method in accordance with JIS K-2605 (1996).
[Softening point ~
The measurement was performed according to JIS K-2207 (1996) (ring and ball method).
[Hue]
The measurement was performed in accordance with ASTM D-1544-63T using a 50% by weight toluene solution.

The evaluation methods and evaluation criteria for the physical properties of the rubber composition are shown below.
[Wet grip]
Using a viscoelasticity measuring device (manufactured by Rheometrics), tan δ was measured at a temperature of 0° C., a strain of 5%, and a frequency of 15 Hz, and the value at 0° C. was evaluated as wet grip performance.
When tan δ at 0° C. was 0.27 or more, the wet grip property was judged to be good, and when it was 0.29 or more, the wet grip property was judged to be particularly excellent.
[Ice grip]
Using a viscoelasticity measuring device (manufactured by Rheometrics), the storage modulus (hereinafter sometimes referred to as E') was measured at a temperature of -20°C, a strain of 5% and a frequency of 15 Hz, and the value at -20°C was evaluated as ice grip property.
When E' at -20°C was 55 MPa or less, the ice gripping property was judged to be good.
[Rolling resistance]
Using a viscoelasticity measuring device (manufactured by Rheometrics), tan δ was measured at a temperature of 60° C., a strain of 5%, and a frequency of 15 Hz, and the value at 60° C. was evaluated as the rolling resistance.
When tan δ at 60° C. was 0.14 or less, the rolling resistance was judged to be good, and when it was 0.12 or less, the rolling resistance was judged to be particularly excellent.
[Wear resistance]
A vulcanized rubber test piece was prepared, and the amount of wear was measured at 23° C. using a Lambourn abrasion tester in accordance with JIS K-6264.
When the abrasion amount at 23° C. was 24 mm ³ /min or less, the abrasion resistance was judged to be good, and when it was 22 mm ³ /min or less, the abrasion resistance was judged to be particularly excellent.

Production Example 1
In a 2-liter glass autoclave, 40% by mass of aliphatic components (saturated and unsaturated compounds having 4 carbon atoms, pentanes, pentenes, isoprene, piperylene, cyclopentadienes, and a mixed oil of saturated and unsaturated compounds having 6 carbon atoms) obtained by decomposition of naphtha as a raw material oil, 12% by mass of aromatic components (styrene, α-methylstyrene, β-methylstyrene, vinyltoluene, indene, unsaturated compounds having 10 carbon atoms, dicyclopentadienes, and a mixed oil of saturated aromatic compounds having 9 carbon atoms) and 48% by mass of DCPD components (saturated and unsaturated compounds having 5 carbon atoms, dicyclopentadiene, dicyclopentadiene dimer, methyldicyclopentadiene, and methyldicyclopentadiene dimer mixed oil) were prepared and charged. Next, after adjusting to 40° C. under a nitrogen atmosphere, 1.4 parts by mass of boron trifluoride butanol complex was added to 100 parts by mass of the raw material oil and polymerized for 2 hours. Thereafter, the catalyst was deactivated and removed with an aqueous caustic soda solution, the oil phase was recovered, and the unreacted raw material oil was removed from the oil phase by distillation to obtain an aliphatic-aromatic-dicyclopentadiene copolymerized petroleum resin A (sometimes referred to as resin A). The evaluation results are shown in Table 1.

Production Examples 2 to 7
Aliphatic-aromatic-dicyclopentadiene copolymer petroleum resins (referred to as Resins B, C, D, E, F, G and H) were obtained in the same manner as in Production Example 1, except that the feed oil was replaced with a feed oil consisting of 40 mass% aliphatic components, 12 mass% aromatic components and 48 mass% DCPD-type components obtained by cracking naphtha, and the blending ratios of the aliphatic components, aromatic components and DCPD-type components were as shown in Table 1. The evaluation results are shown in Table 1.

Example 1
In a Banbury mixer (volume 1.7 liters), 55 parts by mass of a solution-polymerized terminal-modified styrene-butadiene copolymer rubber (modified S-SBR) (manufactured by ENEOS Material Co., Ltd., (trade name) HPR-340: styrene content 10% by mass) and 45 parts by mass of polyisoprene rubber (IR) (manufactured by ENEOS Material Co., Ltd., (trade name) IR2200) were blended and masticated for 30 seconds, and then 2 parts by mass of stearic acid (manufactured by New Japan Chemical Co., Ltd.), 70 parts by mass of silica (manufactured by Tosoh Silica, (trade name) Nipsil AQ), 5.6 parts by mass of a silane coupling agent (manufactured by Shin-Etsu Silicone, (trade name) KBE46), and 20 parts by mass of the resin A obtained in Production Example 1 were added to 100 parts by mass of the total diene rubber component, and the total kneading time was 5 minutes, after which the mixture was taken out. The ram pressure and rotation speed were adjusted so that the compound temperature at the time of taking out was 140 ° C. to 150 ° C. The obtained compound was cooled to room temperature, and then 1 part by mass of an antioxidant (manufactured by Ouchi Shinko, (product name) 810NA), 3 parts by mass of zinc oxide (manufactured by Inoue Lime Industry), 1.2 parts by mass of a vulcanization accelerator (1) (manufactured by Ouchi Shinko, (product name) Noccela CZ), 1.5 parts by mass of a vulcanization accelerator (2) (manufactured by Ouchi Shinko, (product name) Noccela D), and 1.5 parts by mass of sulfur (manufactured by Tsurumi Chemical Industry) as a vulcanizing agent were added thereto, and the mixture was kneaded for about 1 minute (the temperature at the time of removal was 110°C or less), and then sheeted using an 8-inch roll to obtain an unvulcanized rubber composition.
The rubber composition was then vulcanized at a temperature of 150° C. for 30 minutes using a steam heating press to obtain a vulcanized rubber composition. The properties of the vulcanized rubber composition obtained (wet grip, ice grip, rolling resistance, and abrasion resistance) were measured. The results are shown in Table 2.

Examples 2 to 4
Unvulcanized rubber compositions and vulcanized rubber compositions were prepared and evaluated in the same manner as in Example 1, except that resins B, C and D were used instead of resin A. The results are shown in Table 2.

Examples 5 to 6
Unvulcanized rubber compositions and vulcanized rubber compositions were prepared and evaluated in the same manner as in Example 1, except that Resin C was used in the amount shown in Table 2 instead of 20 parts by mass of Resin A. The results are shown in Table 2.

The rubber compositions obtained in Examples 1 to 6 had an excellent balance of wet grip, rolling resistance, and abrasion resistance, and also had excellent ice grip.

Comparative Example 1
An unvulcanized rubber composition and a vulcanized rubber composition were obtained in the same manner as in Example 1, except that Resin A was not used. The evaluation results are shown in Table 3.

Comparative Examples 2 and 3
Unvulcanized and vulcanized rubber compositions were prepared and evaluated in the same manner as in Example 1, except that Resins E and H were used instead of Resin A. The results are shown in Table 3.

Comparative Example 4
An unvulcanized rubber composition and a vulcanized rubber composition were prepared and evaluated in the same manner as in Example 1, except that a petroleum resin (product name: T-REZ RD104, manufactured by ENEOS Corporation; sometimes referred to as Resin I) was used instead of Resin A. The results are shown in Table 3.

Comparative Example 5
An unvulcanized rubber composition and a vulcanized rubber composition were prepared and evaluated in the same manner as in Example 1, except that a petroleum resin (product name: T-REZ RA100, manufactured by ENEOS Corporation; sometimes referred to as Resin J) was used instead of Resin A. The results are shown in Table 3.

Comparative Examples 6 and 7
Except for using the amount shown in Table 3 in place of 20 parts by mass of Resin A, unvulcanized rubber compositions and vulcanized rubber compositions were prepared and evaluated in the same manner as in Example 1. The results are shown in Table 3.

Comparative Example 8
Except for changing the mass ratio to modified S-SBR/IR=45/55, unvulcanized rubber compositions and vulcanized rubber compositions were prepared and evaluated in the same manner as in Example 1. The results are shown in Table 3.

Example 7
In a Banbury mixer (volume 1.7 liters), 55 parts by mass of natural rubber (RSS#3) and 45 parts by mass of solution-polymerized terminal-modified styrene-butadiene copolymer rubber (modified S-SBR) (manufactured by JSR Corporation, (trade name) HPR-350) were blended and masticated for 30 seconds to obtain a total of 100 parts by mass of rubber components. Then, 2 parts by mass of stearic acid (manufactured by New Japan Chemical Co., Ltd.), 70 parts by mass of silica (manufactured by Tosoh Silica, (trade name) Nipsil AQ), 5.6 parts by mass of a silane coupling agent (manufactured by Shin-Etsu Silicone, (trade name) KBE46), and 20 parts by mass of the resin A obtained in Production Example 1 were added to the resulting mixture, and the mixture was taken out after a total kneading time of 5 minutes. The ram pressure and rotation speed were adjusted so that the compound temperature at the time of taking out was 140°C to 150°C. The obtained compound was cooled to room temperature, and then 1 part by mass of an antioxidant (manufactured by Ouchi Shinko, (product name) 810NA), 3 parts by mass of zinc oxide (manufactured by Inoue Lime Industry), 1.2 parts by mass of a vulcanization accelerator (1) (manufactured by Ouchi Shinko, (product name) Noccela CZ), 1.5 parts by mass of a vulcanization accelerator (2) (manufactured by Ouchi Shinko, (product name) Noccela D), and 1.5 parts by mass of sulfur (manufactured by Tsurumi Chemical Industry) as a vulcanizing agent were added thereto, and the mixture was kneaded for about 1 minute (the temperature at the time of removal was 110°C or less), and then sheeted using an 8-inch roll to obtain an unvulcanized rubber composition.
The rubber composition was then vulcanized at a temperature of 150° C. for 30 minutes using a steam heating press to obtain a vulcanized rubber composition. The properties of the vulcanized rubber composition obtained (wet grip, ice grip, rolling resistance, and abrasion resistance) were measured. The results are shown in Table 4.

Examples 8 to 10
Unvulcanized and vulcanized rubber compositions were prepared and evaluated in the same manner as in Example 7, except that Resins B, C and D were used instead of Resin A. The results are shown in Table 4.

Examples 11 and 12
Unvulcanized rubber compositions and vulcanized rubber compositions were prepared and evaluated in the same manner as in Example 7, except that Resin C was used in the amount shown in Table 4 instead of 20 parts by mass of Resin A. The results are shown in Table 4.

　実施例７～１２により得られるゴム組成物は、ウェットグリップ性、転がり抵抗性と耐摩耗性のバランスに優れ、さらにアイスグリップ性にも優れるものであった。

The rubber compositions obtained in Examples 7 to 12 had an excellent balance of wet grip properties, rolling resistance and abrasion resistance, and further had excellent ice grip properties.

Comparative Example 9
An unvulcanized rubber composition and a vulcanized rubber composition were obtained in the same manner as in Example 7, except that Resin A was not used. The evaluation results are shown in Table 5.

Comparative Examples 10 to 13
Unvulcanized rubber compositions and vulcanized rubber compositions were prepared and evaluated in the same manner as in Example 7, except that Resins E, F, G and H were used instead of Resin A. The results are shown in Table 5.

Comparative Example 14
An unvulcanized rubber composition and a vulcanized rubber composition were prepared and evaluated in the same manner as in Example 7, except that a petroleum resin (product name: T-REZ RD104, manufactured by ENEOS Corporation; sometimes referred to as Resin I) was used instead of Resin A. The results are shown in Table 5.

Comparative Example 15
An unvulcanized rubber composition and a vulcanized rubber composition were prepared and evaluated in the same manner as in Example 7, except that a petroleum resin (product name: T-REZ RA100, manufactured by ENEOS Corporation; sometimes referred to as Resin J) was used instead of Resin A. The results are shown in Table 5.

Comparative Examples 16 and 17
Unvulcanized rubber compositions and vulcanized rubber compositions were prepared and evaluated in the same manner as in Example 7, except that the amount shown in Table 5 was used instead of 20 parts by mass of Resin A. The results are shown in Table 5.

The claims, specifications and abstracts of Japanese Patent Application No. 2023-068257 and Japanese Patent Application No. 2023-068258, filed on April 19, 2023, are hereby incorporated by reference in their entirety as the disclosure of the specification of the present invention.

According to the present invention, by blending a specific diene rubber with an aliphatic-aromatic-dicyclopentadiene copolymer petroleum resin having a specific amount of double bonds, it is possible to provide a rubber composition that has an excellent balance of wet grip, rolling resistance, and abrasion resistance, as well as excellent ice grip. This rubber composition can be used as tire tread rubber to provide tires and all-season tires, and its industrial value is extremely high.

Claims (6)

A rubber composition comprising a diene rubber and an aliphatic-aromatic-dicyclopentadiene copolymer petroleum resin which is a copolymer resin of a C5 fraction, dicyclopentadienes, and a C9 fraction of petroleum, the rubber composition comprising 5 to 40 parts by mass of the aliphatic-aromatic-dicyclopentadiene copolymer petroleum resin per 100 parts by mass of the diene rubber, the diene rubber comprising more than 50% by mass of a styrene-butadiene copolymer rubber and/or a natural rubber, and the aliphatic-aromatic-dicyclopentadiene copolymer petroleum resin satisfying all of the following properties (1) to (5):
(1) As measured by proton NMR, (i) the ratio of aliphatic hydrogen derived from aliphatic components observed at 0.2 to 4.0 ppm is more than 85% and not more than 89%, (ii) the ratio of dicyclopentadiene double bond hydrogen derived from double bonds of dicyclopentadiene components observed at 4.4 to 6.3 ppm is 7% or more and 10% or less, and (iii) the ratio of aromatic hydrogen derived from aromatic components observed at 6.3 to 7.6 ppm is 1% or more and not more than 8%.
(2) The weight average molecular weight measured by gel permeation chromatography in accordance with JIS K-0124 (2011) using standard polystyrene as the standard substance is 2,000 or more and 3,000 or less, and the weight average molecular weight/number average molecular weight is 2.0 or more and 3.0 or less.
(3) The bromine number measured in accordance with JIS K-2605 (1996) is 45 g-Br2/100 g or more and 60 g-Br2/100 g or less.
(4) The softening point measured in accordance with JIS K-2207 (1996) (ring and ball method) is 85° C. or higher and 115° C. or lower.
(5) The Gardner hue of a 50% by mass solution in toluene, as measured in accordance with ASTM D-1544-63T, is 5 or greater and 10 or less. The rubber composition according to claim 1, characterized in that the styrene-butadiene copolymer rubber has a styrene content of 25 mass% or less. The rubber composition according to claim 1 or 2, characterized in that the diene rubber is a mixed diene rubber of styrene-butadiene copolymer rubber and at least one rubber selected from the group consisting of isoprene rubber, natural rubber, and butadiene rubber. The rubber composition according to any one of claims 1 to 3, characterized in that the diene rubber is a mixed diene rubber of styrene-butadiene copolymer rubber and natural rubber. The rubber composition according to any one of claims 1 to 4, which is a vulcanized rubber composition that constitutes a tire. A tire having a tread made of the rubber composition according to claim 5.