Aliphatic hydrocarbon-aromatic compound-dicyclopentadiene copolymer petroleum resin and rubber composition

Abstract

To provide: a novel aliphatic hydrocarbon-aromatic compound-dicyclopentdiene copolymer petroleum resin which improves fracture resistance characteristics of rubber and enables both a wet grip property and a rolling resistance property of a tire; and a rubber composition using the same.SOLUTION: There is provided, an aliphatic hydrocarbon-aromatic compound-dicyclopentadiene copolymer petroleum resin, which is a copolymer of an unsaturated aliphatic hydrocarbon which is a thermolysis fraction of petroleum, an unsaturated aromatic compound, and dicyclopentadienes. The copolymer petroleum resin satisfies characteristics including: (1) a softening point of 80-130°C; (2) Mw of 1500-2500, Mz of 2500-6000, and Mz / Mw of 1.5-2.5; (3) (I) an area ratio of aliphatic hydrogens of 69-74%, (II) an area ratio of acyclic double bond-derived hydrogen of 2.0-4.0%, (III) an area ratio of hydrogen derived from dicyclopentadiene double bond of 1.3-2.5%, and (IV) an area ratio of aromatic hydrogen of 20-27%.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to an aliphatic hydrocarbon-aromatic compound-dicyclopentadiene copolymer petroleum resin and a rubber composition using the same, and in particular to a novel aliphatic hydrocarbon-aromatic compound-dicyclopentadiene copolymer petroleum resin that, when used in the tread portion of a tire, improves fracture resistance, which is an indicator of tire durability, and also enables both wet grip performance and rolling resistance to be achieved, and a rubber composition using the same. [Background technology]

[0002] In recent years, demands for tire performance have increased in line with the advancement of automobile performance and functionality. For example, there is a demand for tires with improved wet grip and rolling resistance, which are mutually exclusive. Furthermore, electric vehicles and plug-in hybrid vehicles equipped with drive batteries, which increase the weight of their vehicles, place greater loads on their tires, and therefore require tires with improved durability. Conventionally, techniques have been used to improve tire wet grip and rolling resistance by compounding silica into rubber, and to improve rolling resistance and abrasion resistance by using terminal-modified rubber, in which functional groups that have a high affinity with or can chemically bond to silica are introduced at the terminals.

[0003] For the purpose of improving the mechanical properties of tires and imparting good adhesion to unvulcanized rubber compositions, it has been proposed to blend an aliphatic / aromatic copolymer resin (see, for example, Patent Document 1) or an aliphatic / alicyclic copolymer resin (see, for example, Patent Document 2) into rubber.

[0004] Furthermore, in order to achieve high control performance on both dry and wet road surfaces, it has been proposed to blend thermoplastic resins such as C5 resin, C5 / C9 resin, and C9 resin with a rubber component containing 70% by mass or more of natural rubber (see, for example, Patent Document 3).

[0005] Furthermore, it has been proposed to compound an aliphatic-aromatic-dicyclopentadiene copolymer petroleum resin with diene rubber in order to improve the wet grip, rolling resistance, and abrasion resistance of tires and to improve processability (see, for example, Patent Document 4). [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Patent No. 5309529 [Patent Document 2] Patent No. 5375101 [Patent Document 3] Patent No. 6346325 [Patent Document 4] Japanese Patent Publication No. 2020-203962 Summary of the Invention [Problem to be solved by the invention]

[0007] However, the methods proposed in Patent Documents 1 and 2 propose blending natural rubber as the main rubber and carbon black as the filler, and do not consider achieving both wet grip and rolling resistance, while the methods proposed in Patent Documents 3 and 4 do not consider the effect of fracture resistance. There is a need for a new aliphatic hydrocarbon-aromatic compound-dicyclopentadiene copolymer petroleum resin that solves these problems, improves fracture resistance, and enables both wet grip and rolling resistance to be achieved, as well as a rubber composition using the same.

[0008] Therefore, an object of the present invention is to provide a novel petroleum resin that solves the problems of the conventional technology, improves the fracture resistance of a rubber composition, and enables a tire to have both good wet grip performance and good rolling resistance, and a rubber composition using the same. [Means for solving the problem]

[0009] As a result of intensive research into solving the above problems, the present inventors have discovered that an aliphatic hydrocarbon-aromatic compound-dicyclopentadiene copolymer petroleum resin that satisfies specific properties, and a rubber composition using the same, are rubber compositions that exhibit excellent fracture resistance, wet grip properties, and rolling resistance, and have thereby completed the present invention.

[0010] That is, the present invention relates to an aliphatic hydrocarbon-aromatic compound-dicyclopentadienes copolymer petroleum resin, which is a copolymer of unsaturated aliphatic hydrocarbons, unsaturated aromatic compounds, and dicyclopentadienes, which are thermal cracking fractions of petroleum, and which satisfies the following properties (1) to (3): (1) Softening point according to JIS K-2531 (1960) (ring and ball method) is 80 to 130°C. (2) The weight-average molecular weight (hereinafter sometimes referred to as Mw) is 1500 to 2500, the Z-average molecular weight (hereinafter sometimes referred to as Mz) is 2500 to 6000, and the ratio of Mz to Mw (hereinafter sometimes referred to as Mz / Mw) is 1.5 to 2.5, as measured by gel permeation chromatography (hereinafter sometimes referred to as GPC) in accordance with JIS K-0124 (1994) using standard polystyrene as the standard substance. (3) In the proton NMR spectrum measured in deuterated chloroform at room temperature, (I) the area ratio of the peak located at 0.2 to 4.0 ppm due to aliphatic hydrogen is 69 to 74%, (II) the area ratio of the peak located at 4.4 to 5.4 ppm due to acyclic double bond hydrogen is 2.0 to 4.0%, (III) the area ratio of the peak located at 5.4 to 6.3 ppm due to dicyclopentadiene double bond hydrogen is 1.3 to 2.5%, and (IV) the area ratio of the peak located at 6.3 to 7.6 ppm due to aromatic hydrogen is 20 to 27%.

[0011] The present invention will be described in detail below.

[0012] The aliphatic hydrocarbon-aromatic compound-dicyclopentadiene copolymer petroleum resin of the present invention is obtained by polymerization of a pyrolysis fraction obtained by separation and refining of petroleum products. For example, it is a petroleum resin obtained by copolymerizing an aliphatic hydrocarbon fraction, such as a C5 fraction (e.g., a fraction with a boiling point range of 20 to 110°C), an aromatic compound fraction, such as a C9 fraction (e.g., a fraction with a boiling point range of 140 to 280°C), and optionally a dicyclopentadiene fraction. The petroleum resin satisfies the properties (1) to (3) above. The petroleum products used in this process may include petroleum-derived petroleum products, such as naphtha, plant-derived oils, such as bioethanol and bionaphtha, and oils derived from chemically recycled plastics, such as polyolefins, polyvinyl chloride, acrylics, and polystyrene.

[0013] The aliphatic hydrocarbon components constituting the aliphatic hydrocarbon-aromatic compound-dicyclopentadiene copolymer petroleum resin of the present invention include components belonging to a fraction called a C5 fraction, which is an aliphatic hydrocarbon fraction, such as fractions with a boiling point range of 20 to 110°C, more specifically linear unsaturated aliphatic hydrocarbons such as isoprene and piperylene; cyclic unsaturated aliphatic hydrocarbons such as cyclopentadiene and methylcyclopentadiene; and mixtures thereof. Furthermore, since cyclopentadienes have the ability to dimerize and become dicyclopentadienes during storage, a C5 fraction containing cyclopentadienes may also contain dicyclopentadienes, which are their dimers.

[0014] Examples of aromatic compound components constituting the aliphatic hydrocarbon-aromatic compound-dicyclopentadiene copolymer petroleum resin of the present invention include a fraction called a C9 fraction, which is an aromatic compound fraction, such as a fraction having a boiling point range of 140 to 280°C, more specifically, unsaturated aromatic compounds having 8 carbon atoms, such as styrene; unsaturated aromatic compounds such as α-methylstyrene, vinyltoluene, indene, 1-methylindene, 2-methylindene, and 3-methylindene; and mixtures thereof.

[0015] The dicyclopentadiene component constituting the aliphatic hydrocarbon-aromatic compound-dicyclopentadiene copolymer petroleum resin of the present invention may be any dicyclopentadiene, such as dicyclopentadiene, methyldicyclopentadiene, dimethyldicyclopentadiene, and mixtures thereof. The dicyclopentadienes may also be those contained as the C9 component.

[0016] The novel aliphatic hydrocarbon-aromatic compound-dicyclopentadiene copolymer petroleum resin of the present invention (1) has a softening point according to JIS K-2531 (1960) (ring and ball method) of 80 to 130°C, preferably 85 to 125°C. If the softening point is less than 80°C, the wet grip performance will be poor when the composition is blended with rubber to form a tire, and if the softening point exceeds 130°C, the rubber composition will have poor rolling resistance when formed into a tire.

[0017] The novel aliphatic hydrocarbon-aromatic compound-dicyclopentadiene copolymer petroleum resin of the present invention has an Mw of 1500-2500, an Mz of 2500-6000, and an Mz / Mw ratio of 1.5-2.5, as measured by GPC in accordance with JIS K-0124 (1994) using standard polystyrene as the standard substance. If the Mw is less than 1500 or the Mz is less than 2500, the wet grip performance of the tire formed from the composition blended with rubber will be poor. If the Mw is more than 2500 or the Mz is more than 6000, the rolling resistance of the tire formed from the composition blended with rubber will be poor. Furthermore, if the Mz / Mw ratio is less than 1.5, the fracture resistance of the tire formed from the composition blended with rubber will be poor. If the Mz / Mw ratio is more than 2.5, the rubber composition will have poor compatibility, resulting in poor rolling resistance.

[0018] The novel aliphatic hydrocarbon-aromatic compound-dicyclopentadiene copolymer petroleum resin of the present invention is a petroleum resin that satisfies the following conditions: (I) an aliphatic hydrogen area ratio of 69 to 74%, (II) an acyclic double bond hydrogen area ratio of 2.0 to 4.0%, (III) a dicyclopentadiene double bond hydrogen area ratio of 1.3 to 2.5%, and (IV) an aromatic hydrogen area ratio of 20 to 27%. Each hydrogen area ratio can be measured by proton NMR using deuterated chloroform as a solvent, as a percentage of the peak area of ​​the spectrum measured and observed, under the following conditions (A) to (D). (a) Determine it based on the area ratio of hydrogen derived from aliphatic components observed between 0.2 and 4.0 ppm. (a) Determined from the area ratio of hydrogen derived from the double bond of the non-cyclic component observed at 4.4 to 5.4 ppm. (c) Determined from the area ratio of hydrogen derived from the double bonds of dicyclopentadiene components observed at 5.4 to 6.3 ppm. (d) Determined from the area ratio of hydrogen derived from aromatic components observed between 6.3 and 7.6 ppm.

[0019] The novel aliphatic hydrocarbon-aromatic compound-dicyclopentadiene copolymer petroleum resin of the present invention satisfies all of the properties (I) to (IV) and therefore has excellent compatibility with rubber, particularly diene rubber, and when made into a tire, it enables the tire to have excellent performance.

[0020] Furthermore, the novel aliphatic hydrocarbon-aromatic compound-dicyclopentadiene copolymer petroleum resin of the present invention exhibits an excellent balance between fracture resistance and flexibility, particularly when blended with rubber. (4) When 100 parts by weight of styrene-butadiene rubber is blended with 30 parts by weight of the aliphatic hydrocarbon-aromatic compound-dicyclopentadiene copolymer petroleum resin, 1.5 parts by weight of sulfur, and 2.5 parts by weight of a sulfenamide vulcanization accelerator, and the resulting vulcanized rubber is subjected to a tensile test in accordance with JIS K-6251, it is preferable that the resulting breaking strength (MPa) and breaking elongation (%) satisfy the relationship: breaking strength (MPa) × breaking elongation (%) > 500.

[0021] The novel aliphatic hydrocarbon-aromatic compound-dicyclopentadiene copolymer petroleum resin of the present invention can be produced by any method, including, for example, a mixture containing an aliphatic hydrocarbon fraction (C5 fraction) with a boiling point range of 20 to 110°C obtained by thermal cracking of petroleum, an aromatic compound fraction (C9 fraction) with a boiling point range of 140 to 280°C, and optionally a dicyclopentadiene fraction, to which a catalyst is added and heated for polymerization. The catalyst used in the polymerization is not particularly limited, and examples include aluminum trichloride, aluminum tribromide, boron trifluoride, and complexes thereof. The solvent used in the polymerization can be saturated hydrocarbons from the C5 fraction and the C9 fraction.

[0022] The polymerization temperature during production is not particularly limited, but is preferably 20 to 80°C, and particularly preferably 30 to 60°C, as this results in 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 feedstock oil, and typically, for example, 0.1 to 2.0% by weight of catalyst and 0.1 to 10 hours of polymerization time are preferred. The reaction pressure is also not particularly limited, with atmospheric pressure to 1 MPa being preferred. The atmosphere is also not particularly limited, with a nitrogen atmosphere being preferred.

[0023] The novel aliphatic hydrocarbon-aromatic compound-dicyclopentadiene copolymer petroleum resin of the present invention, when blended with rubber, particularly diene rubber, results in a rubber composition exhibiting excellent fracture resistance, wet grip properties, and rolling resistance. Examples of diene rubbers include natural rubber, polyisoprene rubber, polybutadiene rubber, and styrene-butadiene copolymer rubber. These may be used alone or in combination. The diene rubber may be produced by anionic polymerization or emulsion polymerization. The molecular terminals of the diene rubber may be modified with amine, amide, silyl, alkoxysilyl, carboxyl, or hydroxyl groups, or may be epoxidized. Because of their excellent compatibility with the aliphatic hydrocarbon-aromatic compound-dicyclopentadiene copolymer petroleum resin, it is particularly preferred to use at least one of natural rubber, polybutadiene rubber, and polyisoprene rubber in combination with the styrene-butadiene copolymer rubber. The rubber composition preferably contains 1 to 50 parts by weight of the aliphatic hydrocarbon-aromatic compound-dicyclopentadiene copolymer petroleum resin per 100 parts by weight of diene rubber, since the rubber composition will be a tire rubber composition and tire with excellent wet grip properties, fuel economy and fracture resistance.

[0024] The rubber composition can also contain silica to improve wet grip and rolling resistance. The type of silica used is not particularly limited, and those used in commercially available rubber compositions can be used. Among these, wet silica (hydrated silica), dry silica (anhydrous silicic acid), colloidal silica, etc. can be used, with wet silica being particularly preferred. The amount of silica used is preferably in the range of 20 to 200 parts by weight, more preferably 30 to 150 parts by weight, per 100 parts by weight of diene rubber, in order to provide a rubber composition with excellent wet grip, rolling resistance, and processability.

[0025] 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 diene rubber and the silica is strengthened via the silane coupling agent, thereby improving wet grip performance, rolling resistance, and fracture resistance. Examples of silane coupling agents include sulfide-based, mercapto-based, vinyl-based, amino-based, epoxy-based, glycidyl-based, nitro-based, and chloro-based silane coupling agents. These silane coupling agents can be used alone or in combination of two or more.

[0026] In addition to the silica, the rubber composition may contain a reinforcing filler such as carbon black, and the carbon black may be of grades such as SAF, ISAF, HAF, FEF, SRF, etc. The amount of carbon black is not particularly limited, but is preferably 1 to 100 parts by weight per 100 parts by weight of the diene rubber.

[0027] The rubber composition may further contain compounding agents used in ordinary resin compositions or rubber compositions. For example, compounding agents such as crosslinking agents including sulfur, vulcanization accelerators, stearic acid, zinc oxide, plasticizers, oils, waxes, and antioxidants may be added. Commercially available compounds can be suitably used as these compounding agents.

[0028] Furthermore, the rubber composition may be of any composition, form, or shape as long as it contains rubber, and may be a crosslinked product (vulcanized product) that contains a crosslinking agent, a vulcanization accelerator, a vulcanization accelerator aid, etc. and has been subjected to crosslinking (vulcanization). In particular, by using the rubber composition as a tire tread, it is possible to provide a tire that is excellent in wet grip performance, rolling resistance, and durability. [Effects of the Invention]

[0029] The novel aliphatic hydrocarbon-aromatic compound-dicyclopentadiene copolymer petroleum resin of the present invention, when blended particularly with a rubber component, improves fracture resistance and makes it possible to provide a rubber composition that achieves both wet grip performance and rolling resistance as a tire. [Example]

[0030] The present invention will be described below with reference to examples, but the present invention is not limited to these examples. The raw material oils used in the examples and comparative examples and the petroleum resins obtained were analyzed using the following methods.

[0031] 1.Raw materials <Raw oil> The compositions of the C5 fraction ((A) and (B)) with a boiling range of 20 to 110°C, which is an aliphatic hydrocarbon fraction obtained by cracking and refining naphtha, the C9 fraction ((A) and (B)) with a boiling range of 140 to 280°C, which is an aromatic compound fraction, and the dicyclopentadiene fraction are shown in Tables 1 to 3. In Tables 1 to 3, DCPD is an abbreviation for dicyclopentadiene, and CPD is an abbreviation for cyclopentadiene.

[0032] [Table 1]

[0033] [Table 2]

[0034] [Table 3]

[0035] <Catalyst for petroleum resin production> Boron trifluoride phenol: 30% by weight of boron trifluoride (manufactured by Stella Chemifa Co., Ltd.). Boron trifluoride butanol: 30% by weight of boron trifluoride (manufactured by Stella Chemifa Co., Ltd.).

[0036] <Rubber> Styrene-butadiene rubber: SL563 manufactured by JSR Corporation (trade name). Isoprene rubber: IR2200 manufactured by JSR Corporation (trade name).

[0037] <Compound agent> Silica: Nipsil AQ manufactured by Tosoh Silica Corporation (trade name). Silane coupling agent: CABRUS2 manufactured by Osaka Soda Co., Ltd. (trade name). Carbon black: Asahi #70 manufactured by Asahi Carbon Co., Ltd. (trade name). Oil: Diana Process Oil AH-16 manufactured by Idemitsu Kosan Co., Ltd. (trade name). Stearic acid: Reagent manufactured by Fujifilm Wako Pure Chemical Corporation. Zinc oxide: Manufactured by Inoue Lime Industry Co., Ltd. Antioxidant: Nocrack 6C manufactured by Ouchi Shinko Chemical Industrial Co., Ltd. (trade name). Wax: Sunoc manufactured by Ouchi Shinko Chemical Industrial Co., Ltd. (trade name). Sulfur: Sulfax 5 manufactured by Tsurumi Chemical Industry Co., Ltd. (trade name). Vulcanization accelerator 1: Noxeller CZ manufactured by Ouchi Shinko Chemical Industrial Co., Ltd. (trade name). Vulcanization accelerator 2: Noxeller D manufactured by Ouchi Shinko Chemical Industrial Co., Ltd. (trade name).

[0038] 2. Analytical method <Analysis of raw material oil components> Analysis was carried out using gas chromatography in accordance with JIS K-0114 (2000).

[0039] <Proton NMR measurement> The proton NMR spectrum was measured in deuterated chloroform using a nuclear magnetic resonance spectrometer (manufactured by JEOL, trade name GSX400, frequency 400 MHz).

[0040] <Measurement of Mn, weight average molecular weight (Mw), and Mz> Using polystyrene as a standard substance, measurement was carried out by GPC in accordance with JIS K-0124 (1994).

[0041] <Measurement of softening point> Measurement was carried out according to JIS K-2531 (1960) (ring and ball method).

[0042] <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 50 Hz, and the value at 0°C was used as an index of wet grip performance. A larger tan δ value was determined to indicate better wet grip performance.

[0043] <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 50 Hz, and the value at 60°C was used as an index of rolling resistance. A smaller tan δ value was determined to indicate better rolling resistance.

[0044] <Destruction resistance characteristics> The breaking strength and breaking elongation were measured using a tensile tester (Shimadzu Corporation) in accordance with the test method of JIS K-6251. Those satisfying the condition of breaking strength (MPa) × breaking elongation (%) > 500 were judged to have excellent fracture resistance.

[0045] Example 1 A 2-liter glass autoclave was charged with 200 g of C5(A) fraction (composition see Table 1) obtained by cracking naphtha as feedstock and 300 g of C9 fraction (A) (composition see Table 2) (C5 fraction (A) / C9 fraction (A) = 40 / 60 (wt%)). The mixture was then heated to 40°C under a nitrogen atmosphere, and 0.4 g of premixed boron trifluoride phenol was added to the feedstock, followed by polymerization at 40°C for 2 hours. After the polymerization reaction was completed, aqueous caustic soda was added to neutralize the mixture. The unreacted oil in the oil layer was then distilled to recover an aliphatic hydrocarbon-aromatic compound-dicyclopentadiene copolymer petroleum resin (hereinafter sometimes referred to as petroleum resin A).

[0046] The polymerization conditions and results are shown in Table 4, and the physical properties (molecular weight, softening point, NMR analysis values) of the obtained petroleum resin A are shown in Table 5.

[0047] Next, 30 parts by weight of petroleum resin A was added to 100 parts by weight of styrene-butadiene copolymer rubber (SBR) (manufactured by JSR Corporation) in a Laboplastomill (600 cc capacity). After a total mixing time of 5 minutes, the mixture was removed. The ram pressure and rotation speed were adjusted so that the compound temperature at the time of removal was 120-130°C. After cooling the resulting compound to room temperature, 1.5 parts by weight of sulfur (product name: Sulfax 5, manufactured by Tsurumi Chemical Industry Co., Ltd.), 1.2 parts by weight of vulcanization accelerator 1 (product name: Noccela CZ, manufactured by Ouchi Shinko Chemical Industry Co., Ltd.), and 1.8 parts by weight of vulcanization accelerator 2 (product name: Noccela D, manufactured by Ouchi Shinko Chemical Industry Co., Ltd.) were added and kneaded for 1 minute. The mixture was then sheeted using a roll to obtain an unvulcanized rubber composition. This was then vulcanized using a heated press at 150°C for 30 minutes to obtain a vulcanized rubber.

[0048] The vulcanized rubber thus obtained was subjected to tensile tests to measure its breaking strength and breaking elongation. The obtained petroleum resin A was capable of providing a vulcanized rubber having excellent fracture resistance, with breaking strength x breaking elongation = 864. The results are shown in Table 6.

[0049] Examples 2 to 4 Aliphatic hydrocarbon-aromatic compound-dicyclopentadiene copolymerized petroleum resins (petroleum resins B to D) were obtained in the same manner as in Example 1, except that the blend and amount of raw material oil and the type and amount of polymerization catalyst were as shown in Table 4.

[0050] The physical properties (molecular weight, softening point, NMR analysis values) of the obtained petroleum resins B to D are shown in Table 5, and the evaluation results when vulcanized rubber was prepared in the same manner as in Example 1 are shown in Table 6. It was possible to provide vulcanized rubber with excellent fracture resistance.

[0051] Comparative Examples 1 to 4 Petroleum resins (petroleum resins E to H) were obtained in the same manner as in Example 1, except that the blend and amount of the raw material oil and the type and amount of the polymerization catalyst were as shown in Table 4.

[0052] The physical properties (molecular weight, softening point, NMR analysis values) of the obtained petroleum resins E to H are shown in Table 5, and the evaluation results when vulcanized rubber was prepared in the same manner as in Example 1 are shown in Table 6. None of the obtained petroleum resins E to H could provide vulcanized rubber with excellent fracture resistance.

[0053] Reference example A vulcanized rubber was prepared in the same manner as in Example 1, except that no petroleum resin was added, and the evaluation results are shown in Table 6. The vulcanized rubber obtained was inferior in fracture resistance.

[0054] [Table 4]

[0055] [Table 5]

[0056] [Table 6]

[0057] Example 5 In a Labo Plastomill (600cc capacity), 70 parts by weight of styrene-butadiene copolymer rubber (SBR) (manufactured by JSR Corporation, product name SL563) and 30 parts by weight of isoprene rubber (IR) (manufactured by JSR Corporation, product name IR2200) were masticated for 30 seconds, and then 60 parts by weight of silica (manufactured by Tosoh Silica, product name Nipsil AQ), 4.8 parts by weight of a silane coupling agent (manufactured by Osaka Soda, product name CABRUS2), and 1.0 parts by weight of carbon black (manufactured by Asahi Carbon, product name Asahi To the mixture were added 15 parts by weight of ethanol (#70), 10 parts by weight of oil (Idemitsu Kosan (trade name) Diana Process Oil AH-16), 2 parts by weight of stearic acid (Fujifilm Wako Pure Chemical Industries (reagent)), 3 parts by weight of zinc oxide (Inoue Lime Industry), 1 part by weight of antioxidant (Ouchi Shinko Chemical Industry (trade name) Nocrac 6C), 2 parts by weight of wax (Ouchi Shinko Chemical Industry (trade name) Sunnock), and 15 parts by weight of the petroleum resin A obtained in Example 1, and the compound was taken out after a total mixing time of 5 minutes. The ram pressure and rotation speed were adjusted so that the compound temperature at the time of takeout was 140 to 150°C, and a rubber composition was obtained.

[0058] Then, 1.5 parts by weight of sulfur (Tsurumi Chemical Industry Co., Ltd. (trade name) Sulfax 5), 1.2 parts by weight of vulcanization accelerator 1 (Ouchi Shinko Chemical Industry Co., Ltd. (trade name) Noccela CZ), and 1.8 parts by weight of vulcanization accelerator 2 (Ouchi Shinko Chemical Industry Co., Ltd. (trade name) Noccela D) were added and kneaded for 1 minute, and then sheeted using an 8-inch roll to obtain an unvulcanized rubber composition. Thereafter, vulcanization was carried out using a heated press at a vulcanization temperature of 150°C for 30 minutes to obtain a vulcanized rubber composition.

[0059] The wet grip property and rolling resistance of the obtained vulcanized rubber composition were measured and the results are shown in Table 7.

[0060] Examples 6 to 8 Rubber compositions were prepared and evaluated in the same manner as in Example 5, except that petroleum resin B, C, or D was used instead of petroleum resin A. The results are shown in Table 7.

[0061] Example 9 A rubber composition was prepared in the same manner as in Example 5, except that 30 parts by weight of petroleum resin A was used instead of 15 parts by weight, and the rubber composition was evaluated. The results are shown in Table 7.

[0062] Comparative Example 1 A rubber composition was obtained in the same manner as in Example 5, except that petroleum resin A was not used. The obtained rubber composition had poor wet grip properties. The evaluation results are shown in Table 7.

[0063] Comparative Examples 6 to 9 Rubber compositions were prepared and evaluated in the same manner as in Example 1, except that petroleum resins E, F, G, and H were used instead of petroleum resin A. It was difficult for the resulting rubber compositions to achieve both wet grip performance and low rolling resistance. The results are shown in Table 7.

[0064] [Table 7] [Industrial Applicability]

[0065] The aliphatic hydrocarbon-aromatic compound-dicyclopentadiene copolymer petroleum resin of the present invention makes it possible to provide a rubber composition that is excellent in fracture resistance, wet grip properties, and rolling resistance. The rubber composition can be used as a tire tread rubber, and therefore has extremely high industrial value.

Claims

1. An aliphatic hydrocarbon-aromatic compound-dicyclopentadienes copolymer petroleum resin is a copolymer of unsaturated aliphatic hydrocarbons, which are thermal cracking fractions of petroleum, unsaturated aromatic compounds, and dicyclopentadienes, and is characterized by satisfying the following properties (1) to (3): (1) A softening point according to JIS K-2531 (1960) (ring and ball method) of 80 to 130°C. (2) A weight-average molecular weight (Mw) of 1,500 to 2,500, a Z-average molecular weight (Mz) of 2,500 to 6,000, and a ratio of the Z-average molecular weight to the weight-average molecular weight (Mz / Mw) of 1.5 to 2.5, as measured by gel permeation chromatography in accordance with JIS K-0124 (1994) using standard polystyrene as the standard substance. (3) In a proton NMR spectrum measured in deuterated chloroform at room temperature, (I) the area ratio of the peak located at 0.2 to 4.0 ppm due to aliphatic hydrogen is 69 to 74%, (II) the area ratio of the peak located at 4.4 to 5.4 ppm due to acyclic double bond hydrogen is 2.0 to 4.0%, (III) the area ratio of the peak located at 5.4 to 6.3 ppm due to dicyclopentadiene double bond hydrogen is 1.3 to 2.5%, and (IV) the area ratio of the peak located at 6.3 to 7.6 ppm due to aromatic hydrogen is 20 to 27%.

2. The aliphatic hydrocarbon-aromatic compound-dicyclopentadiene copolymer petroleum resin according to claim 1, further satisfying the following characteristic (4): (4) When a vulcanized rubber obtained by compounding 100 parts by weight of styrene-butadiene rubber with 30 parts by weight of aliphatic hydrocarbon-aromatic compound-dicyclopentadiene copolymer petroleum resin, 1.5 parts by weight of sulfur, and 2.5 parts by weight of a sulfenamide vulcanization accelerator and press-vulcanizing the rubber at 150°C for 30 minutes is subjected to a tensile test in accordance with JIS K-6251, the breaking strength (MPa) x breaking elongation (%) > 500 is satisfied.

3. The aliphatic hydrocarbon-aromatic compound-dicyclopentadiene copolymer petroleum resin according to claim 1 or 2, characterized in that the thermal cracking fraction of petroleum is a thermal cracking oil containing plant-derived oil and / or chemically recycled oil.

4. A rubber composition comprising at least the aliphatic hydrocarbon-aromatic compound-dicyclopentadiene copolymer petroleum resin according to any one of claims 1 to 3, and a diene rubber.

5. 5. The rubber composition according to claim 4, wherein the rubber composition contains 1 to 50 parts by weight of the aliphatic hydrocarbon-aromatic compound-dicyclopentadiene copolymer petroleum resin per 100 parts by weight of the diene rubber.

6. 6. The rubber composition according to claim 4, wherein the diene rubber contains 10% by weight or more of styrene-butadiene rubber.

7. 7. The rubber composition according to claim 4, further comprising 20 to 200 parts by weight of silica per 100 parts by weight of the diene rubber.

8. A tire comprising the rubber composition according to any one of claims 4 to 7.

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