Tackifiers for tires, rubber compositions for tires, and tires

Abstract

To provide a tire tackifier, a tire rubber composition, and a tire that is a vulcanized product of the tire rubber composition, for manufacturing a tire with excellent wet grip and fracture resistance. [Solution] The tackifier for tires contains constituent units derived from isopropenyltoluene, and its number-average molecular weight in terms of standard polystyrene, measured by gel permeation chromatography (GPC), is 800 or more and less than 4000, and the degree of dispersion of the molecular weight distribution (weight-average molecular weight / number-average molecular weight) is less than 1.50.

Description

Technical Field

[0001] The present invention relates to an adhesion promoter for tires, a rubber composition for tires, and a tire.

Background Art

[0002] Conventionally, it is known that tires are manufactured using a rubber composition for tires containing a rubber component and an adhesion promoter.

[0003] As such a rubber composition for tires, a rubber composition for tires containing SBR (styrene-butadiene copolymer rubber) and an adhesion promoter (a copolymer of isopropenyltoluene and indene, number average molecular weight 930, dispersity of molecular weight distribution 1.73) has been proposed (see, for example, Example 2 of Patent Document 1).

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] On the other hand, from the viewpoint of safety, tires are required to have improved wet grip performance (braking performance on a wet road surface) indicating braking performance.

[0006] In addition, tires are required to have improved fracture resistance.

[0007] [[ID=:47]]The present invention provides an adhesion promoter for tires, a rubber composition for tires, and a tire which is a vulcanizate of the rubber composition for tires, for manufacturing a tire excellent in wet grip performance and fracture resistance.

Means for Solving the Problems

[0008] The present invention [1] is a tire tackifier comprising a constituent unit derived from isopropenyltoluene, having a number-average molecular weight of 800 or more and less than 4000 in terms of standard polystyrene as measured by gel permeation chromatography (GPC), and a degree of dispersion of molecular weight distribution (weight-average molecular weight / number-average molecular weight) of less than 1.50.

[0009] The present invention [2] includes the tire tackifier described in [1] above, which contains constituent units derived from the C5 fraction.

[0010] The present invention [3] includes the tire tackifier described in [1] or [2] above, wherein the content of constituent units derived from isopropenyltoluene is 97 mol% or more.

[0011] The present invention [4] contains a tire tackifier according to any one of the above [1] to [3], wherein the content of a compound with a molecular weight of 500 or less on a standard polystyrene basis, as measured by gel permeation chromatography (GPC), is 12.0% or less.

[0012] The present invention [5] includes a tire rubber composition comprising a tire tackifier described in any one of the above [1] to [4] and a rubber component.

[0013] The present invention [6] includes a tire, which is a vulcanized product of the tire rubber composition described in [5] above. [Effects of the Invention]

[0014] The tackifier for tires of the present invention contains structural units derived from isopropenyltoluene, has a number-average molecular weight equivalent to standard polystyrene measured by gel permeation chromatography (GPC) of 800 or more and less than 4000, and a degree of dispersion of molecular weight distribution (weight-average molecular weight / number-average molecular weight) of less than 1.50. Therefore, it is possible to manufacture tires with excellent wet grip and fracture resistance.

[0015] The rubber composition for tires of the present invention contains the tackifier for tires of the present invention. Therefore, tires excellent in wet grip performance and fracture resistance can be manufactured.

[0016] The tire of the present invention is a vulcanizate of the rubber composition for tires of the present invention. Therefore, it is excellent in wet grip performance and fracture resistance.

Brief Description of the Drawings

[0017] [Figure 1] FIG. 1 is a gel permeation chromatogram of the tackifier for tires of Production Example 1 and Production Comparative Example 2.

Embodiments for Carrying Out the Invention

[0018] 1. Tackifier for Tires The tackifier for tires is a polymer containing structural units derived from isopropenyltoluene.

[0019] Such a polymer is obtained by polymerizing polymerization components.

[0020] (Polymerization Components) The polymerization components include isopropenyltoluene as an essential component.

[0021] Also, from the viewpoint of improving the compatibility with a rubber component (described later) and the wet grip modifying performance, the polymerization components may include other components copolymerizable with isopropenyltoluene.

[0022] Examples of the other components include α-methylstyrene, indene, vinyltoluene, and unsaturated aliphatic hydrocarbons.

[0023] Examples of the unsaturated aliphatic hydrocarbons include a C4 fraction and a C5 fraction.

[0024] The C4 fraction is obtained by refining and / or cracking petroleum. The C4 fraction is a fraction with a boiling point range of typically -15°C to 45°C under normal pressure, and includes, for example, carbon-4 unsaturated aliphatic hydrocarbons that do not contain conjugated double bonds, and carbon-4 unsaturated aliphatic hydrocarbons that contain conjugated double bonds.

[0025] Examples of carbon-4 unsaturated aliphatic hydrocarbons that do not contain conjugated double bonds include 1-butene, isobutene, and 2-butene.

[0026] An example of a carbon-4 unsaturated aliphatic hydrocarbon containing a conjugated double bond is 1,3-butadiene.

[0027] The C5 fraction is obtained by refining and / or cracking petroleum. The C5 fraction is a fraction with a boiling point range of typically -15°C to 45°C under normal pressure, and includes, for example, unsaturated aliphatic hydrocarbons with 5 carbon atoms that do not contain conjugated double bonds, and unsaturated aliphatic hydrocarbons with 5 carbon atoms that contain conjugated double bonds.

[0028] Examples of unsaturated aliphatic hydrocarbons with 5 carbon atoms that do not contain conjugated double bonds include 1-pentene, 2-methyl-1-butene, 3-methyl-1-butene, and 2-pentene.

[0029] Examples of unsaturated aliphatic hydrocarbons with 5 carbon atoms containing conjugated double bonds include isoprene, 1,3-pentadiene, and cyclopentadiene.

[0030] The C5 fraction preferably does not contain C5 unsaturated aliphatic hydrocarbons containing conjugated double bonds, and consists of C5 unsaturated aliphatic hydrocarbons that do not contain conjugated double bonds.

[0031] Other ingredients can be used alone or in combination of two or more types.

[0032] Furthermore, all or part of the monomers constituting the polymerization component may be derived from fossil fuels or biomass.

[0033] Fossil fuels include petroleum, coal, natural gas, shale gas, or combinations thereof. Biomass refers to all renewable natural raw materials and their residues, including plant-derived or animal-derived materials such as fungi, yeasts, algae, and bacteria.

[0034] In tire tackifiers, the content of constituent units derived from isopropenyltoluene is, from the viewpoint of fracture resistance, for example, 65 mol% or more, preferably 70 mol% or more, more preferably 80 mol% or more, even more preferably 90 mol% or more, and particularly preferably 97 mol% or more.

[0035] The proportions of the above constituent units are as follows: 13 It can be measured by 13C-NMR spectroscopy.

[0036] The polymerization component is preferably isopropenyltoluene or isopropenyltoluene and the C5 fraction. In other words, the polymer (tire tackifier) ​​is preferably a homopolymer of isopropenyltoluene or a copolymer of isopropenyltoluene and the C5 fraction (a tire tackifier containing constituent units derived from isopropenyltoluene and constituent units derived from the C5 fraction). Specifically, from the viewpoint of wet grip, a copolymer of isopropenyltoluene and the C5 fraction is preferred as the polymer (tire tackifier). Also, from the viewpoint of fracture resistance, a homopolymer of isopropenyltoluene is preferred as the polymer (tire tackifier).

[0037] (Method for manufacturing tackifiers for tires) A method for producing a tire tackifier comprises a first step of polymerizing a polymerization component to obtain a reaction product, and a second step of dissolving the reaction product in a good solvent and then adding it to a poor solvent.

[0038] [1st step] In the first step, the polymerization components are polymerized to obtain the reaction product. Specifically, the polymerization components are polymerized at atmospheric pressure in the presence of a Friedel-Crafts catalyst.

[0039] Examples of Friedel-Crafts catalysts include phenolic complexes (e.g., boron trifluoride phenolate complexes).

[0040] The proportion of the Friedel-Crafts catalyst used is, for example, 0.01 to 1 part by mass per 100 parts by mass of the polymerization component.

[0041] The polymerization conditions include a polymerization temperature of, for example, -50°C to 50°C, and a polymerization time of, for example, 10 minutes to 10 hours.

[0042] Furthermore, the above reaction may be carried out in the presence or absence of a solvent. Preferably, the above reaction is carried out in the presence of a solvent.

[0043] Examples of solvents include aliphatic hydrocarbons, alicyclic hydrocarbons, aromatic hydrocarbons, ketones, and alkyl esters. Aromatic hydrocarbons are preferred as solvents. Examples of aromatic hydrocarbons include toluene and xylene. Toluene is preferred as an aromatic hydrocarbon.

[0044] Solvents can be used alone or in combination of two or more types.

[0045] After polymerization, the solvent and / or unreacted polymer components can be removed as needed.

[0046] This yields the reaction product (a solution of the reaction product).

[0047] [Second process] In the second step, the reaction product is dissolved in a good solvent (e.g., acetone, toluene) and then added to a poor solvent (e.g., methanol). This precipitates the reaction product.

[0048] Subsequently, if necessary, the reaction solution containing the reaction product is filtered and then washed with a mixture of the above-mentioned good solvent and poor solvent. This yields a tire tackifier (polymer). By performing the second step, the number-average molecular weight (Mn) and the degree of dispersion of the molecular weight distribution of the tire tackifier, described later, can be adjusted to a predetermined range.

[0049] The softening point of the tackifier for tires is, for example, 115°C to 150°C, preferably 118°C to 140°C, and more preferably 120°C to 130°C.

[0050] If the above softening point falls within the above range, wet grip performance can be improved.

[0051] The above softening point can be measured by the ring-and-ball method (in accordance with JIS K2207).

[0052] The number-average molecular weight (Mn) of tire tackifiers is between 800 and 4000, calculated using standard polystyrene equivalents by gel permeation chromatography (GPC).

[0053] If the number-average molecular weight (Mn) of the tackifier for tires is above the lower limit mentioned above, both wet grip and fracture resistance can be improved.

[0054] On the other hand, if the number-average molecular weight (Mn) of the tackifier for tires is below the lower limit mentioned above, it is not possible to achieve both wet grip and fracture resistance.

[0055] Furthermore, if the number-average molecular weight (Mn) of the tackifier for tires is below the above upper limit, both wet grip and fracture resistance can be improved.

[0056] On the other hand, if the number-average molecular weight (Mn) of the tackifier for tires exceeds the above upper limit, it is not possible to achieve both wet grip and fracture resistance.

[0057] More specifically, the number-average molecular weight (Mn) of the tackifier for tires is 800 or more, preferably 850 or more, more preferably 900 or more, even more preferably 950 or more, particularly preferably 980 or more, and also less than 4000, preferably 3000 or less, more preferably 2000 or less, and even more preferably 1000 or less, from the viewpoint of further improving wet grip performance.

[0058] Furthermore, the number-average molecular weight (Mn) of the tackifier for tires is 800 or more, preferably 850 or more, more preferably 900 or more, even more preferably 950 or more, and less than 4000, preferably 3000 or less, more preferably 2000 or less, even more preferably 1000 or less, and particularly preferably 980 or less, from the viewpoint of further improving resistance to breakage.

[0059] Furthermore, the weight-average molecular weight (Mw) of the tire tackifier is, for example, 800 to 5000, preferably 1000 to 3000, more preferably 1100 to 2000, even more preferably 1200 to 1500, and particularly preferably 1300 to 1400, based on standard polystyrene measurements by gel permeation chromatography (GPC).

[0060] More specifically, the weight-average molecular weight (Mw) of the tackifier for tires is, from the viewpoint of wet grip and fracture resistance, for example, 800 or more, preferably 1000 or more, more preferably 1100 or more, even more preferably 1200 or more, and particularly preferably 1300 or more. Also, from the viewpoint of wet grip and fracture resistance, it is, for example, 5000 or less, preferably 3000 or less, more preferably 2000 or less, even more preferably 1500 or less, and particularly preferably 1400 or less.

[0061] Furthermore, the z-average molecular weight (Mz) of tire tackifiers is, for example, 1000 to 6000, calculated on a standard polystyrene basis using gel permeation chromatography (GPC).

[0062] More specifically, the z-average molecular weight (Mz) of the tackifier for tires is, from the viewpoint of further improving wet grip performance, for example, 1000 or more, preferably 1500 or more, more preferably 1600 or more, even more preferably 1700 or more, particularly preferably 1800 or more, and also, for example, 6000 or less, preferably 3000 or less, more preferably 2000 or less, and even more preferably 1900 or less.

[0063] Furthermore, the z-average molecular weight (Mz) of the tire tackifier is, for example, 1000 or more, preferably 1500 or more, more preferably 1600 or more, even more preferably 1700 or more, particularly preferably 1800 or more, most preferably 1900 or more, or, for example, 6000 or less, preferably 3000 or less, more preferably 2000 or less, from the viewpoint of further improving resistance to fracture.

[0064] Furthermore, the degree of dispersion of the molecular weight distribution of the tire tackifier (ratio of weight-average molecular weight (Mw) to number-average molecular weight (Mn) (Mw / Mn)) is less than 1.50.

[0065] If the degree of dispersion of the molecular weight distribution of the tackifier for tires is below the above upper limit, both wet grip and fracture resistance can be improved.

[0066] On the other hand, if the degree of dispersion in the molecular weight distribution of the tackifier for tires exceeds the above upper limit, it is not possible to achieve both wet grip and resistance to damage.

[0067] More specifically, the degree of dispersion of the molecular weight distribution of the tackifier for tires is less than 1.50, preferably 1.40 or less, and for example, 1.10 or more, preferably 1.20 or more, and more preferably 1.30 or more, from the viewpoint of further improving wet grip performance.

[0068] Furthermore, from the viewpoint of further improving resistance to breakage, the degree of dispersion of the molecular weight distribution of the tire tackifier is less than 1.50, preferably 1.45 or less, and for example, 1.10 or more, preferably 1.20 or more, more preferably 1.30 or more, and even more preferably 1.40 or more.

[0069] Furthermore, in the molecular weight distribution of tire tackifiers as measured by gel permeation chromatography (GPC) on a standard polystyrene basis, the content of compounds with a molecular weight of 500 or less as measured by gel permeation chromatography (GPC) on a standard polystyrene basis is, for example, 12.0% or less, preferably 10.0% or less.

[0070] If the content of compounds with a molecular weight of 500 or less, measured by gel permeation chromatography (GPC) on a standard polystyrene basis, is below the above upper limit, both wet grip and fracture resistance can be improved.

[0071] 2. Rubber composition for tires The tire rubber composition comprises a rubber component and a tire tackifier.

[0072] <Rubber components> Examples of rubber components include diene-based rubbers.

[0073] Examples of diene rubbers include natural rubber (NR), styrene-butadiene rubber (SBR), butadiene rubber (BR), isoprene rubber (IR), butyl rubber (IIR), acrylonitrile-butadiene rubber (NBR), ethylene-propylene-diene rubber (EPDM), and chloroprene rubber (CR).

[0074] Preferably, the rubber component is styrene-butadiene rubber (SBR).

[0075] The rubber component can be used alone or in combination of two or more types.

[0076] The proportion of rubber components is, for example, 70 to 95 parts by mass, preferably 80 to 90 parts by mass, per 100 parts by mass of the total amount of rubber components and tire tackifiers.

[0077] <Tire adhesive> The proportion of the tire tackifier is, for example, 5 to 30 parts by mass, preferably 10 to 20 parts by mass, per 100 parts by mass of the rubber component.

[0078] Tire tackifiers can be used alone or in combination of two or more types.

[0079] <Additives> The rubber composition for tires may contain additives in appropriate proportions as needed. Examples of additives include inorganic fillers, rubber reinforcing agents, softeners, crosslinking agents, crosslinking aids, antioxidants, processing aids, alkoxysilane compounds, surfactants, reaction inhibitors, colorants, dispersants, flame retardants, plasticizers, antioxidants, scorch inhibitors, UV absorbers, antistatic agents, lubricants, antifungal agents, scouring accelerators, dyes (e.g., disperse dyes, acid dyes), inorganic and organic pigments, surfactants, paints, compounds for foaming (e.g., foaming agents, foaming aids), and defoaming agents.

[0080] <Preparation of rubber composition for tires> A rubber composition for tires is obtained by blending and kneading a rubber component, a tire tackifier, and additives as needed.

[0081] 3. Tires A tire is a vulcanized product of a tire rubber composition. Such a tire is obtained by vulcanizing a tire rubber composition.

[0082] Known methods exist for vulcanizing tire rubber compositions. Specifically, first, a vulcanizing agent (e.g., a sulfur-based compound, a peroxide-based crosslinking agent) is added to the tire rubber composition. Next, the mixture is molded using a known molding method (e.g., mold molding), and then heated. This process produces a tire, which is a vulcanized product of the tire rubber composition.

[0083] 4. Effects The tackifier for tires contains structural units derived from isopropenyltoluene, and its number-average molecular weight, measured by gel permeation chromatography (GPC) on a standard polystyrene basis, is between 800 and 4000, with a molecular weight distribution dispersion (weight-average molecular weight / number-average molecular weight) of less than 1.50. Therefore, it is possible to manufacture tires with excellent wet grip and fracture resistance.

[0084] More specifically, the number-average molecular weight of the tire tackifier, measured by gel permeation chromatography (GPC) on a standard polystyrene basis, is 800 or higher. Therefore, the molecular weight distribution of the tire tackifier contains few low-molecular-weight compounds (specifically, compounds with a molecular weight of 500 or less on a standard polystyrene basis, measured by gel permeation chromatography (GPC)). Furthermore, the dispersion degree of the tire tackifier is less than 1.50. In other words, the tire tackifier has few low-molecular-weight compounds and a narrow molecular weight distribution. Such a tire tackifier has fewer low-molecular-weight components that cause a decrease in physical properties, thus increasing mechanical strength and improving fracture resistance. Moreover, because it contains fewer low-molecular-weight components that cause a decrease in thermal properties, it enhances the wet grip modification effect of the tire tackifier, improving wet grip performance. In addition, by using a tire tackifier that falls within the above-mentioned number-average molecular weight range and has a narrow molecular weight distribution, high wet grip performance can be obtained. As described above, it is presumed that controlling the molecular weight and improving the uniform dispersion of the tire tackifier in the rubber increases the tanδ peak intensity of the tire rubber composition, contributing to improved wet grip performance.

[0085] The tire rubber composition contains a tire tackifier. Therefore, it is possible to manufacture tires with excellent wet grip and fracture resistance.

[0086] Tires are vulcanized products of tire rubber compositions. Therefore, they offer excellent wet grip and resistance to damage. [Examples]

[0087] Next, the present invention will be described based on examples and comparative examples, but the present invention is not limited to the following examples. Unless otherwise specified, "parts" and "%" are based on mass. Furthermore, specific numerical values ​​such as blending ratios (content), physical properties, and parameters used in the following description may be replaced with the corresponding upper limits (numerical values ​​defined as "less than or equal to" or "less than") or lower limits (numerical values ​​defined as "greater than or equal to" or "greater than") of the blending ratios (content), physical properties, and parameters described in the "Modes for Carrying Out the Invention" above.

[0088] <Details of ingredients> Details of the abbreviations used in each example and comparative example are described below. SBR: Solution-polymerized polystyrene-butadiene rubber (manufactured by ENEOS Materials, product name "SL552") IPT: Isopropenyltoluene IND: Inden αMS: α-methylstyrene C5:C5 fraction

[0089] <Manufacturing of tackifiers (polymers) for tires> Manufacturing Example 1 (Copolymer of isopropenyltoluene and C5 fraction) [1st step] A 1270 ml autoclave equipped with stirring blades was subjected to a polymerization reaction at 5°C. A mixture of polymerization components (isopropenyltoluene and C5 fraction obtained by the thermal decomposition of petroleum naphtha) and dehydrated purified toluene (polymerization component / toluene = 1 / 1 (volume ratio)) and a Friedel-Crafts catalyst (boron trifluoride phenolate complex diluted 10-fold with dehydrated purified toluene (1.7 times the phenol equivalent)) was continuously supplied to the first stage. The mass ratio of isopropenyltoluene to C5 fraction (isopropenyltoluene / C5 fraction) was 90 / 10, the supply rate of the polymerization component and toluene mixture was 1.0 liter / hour, and the supply rate of the Friedel-Crafts catalyst was 105 milliliters / hour. A reaction mixture was obtained.

[0090] Next, the reaction mixture was transferred to a second autoclave, and the polymerization reaction was continued at 5°C. When the total residence time in the first and second autoclaves reached 2 hours, the reaction mixture was continuously discharged from the autoclaves. When the residence time reached three times the total residence time, 1 liter of the reaction mixture was collected to terminate the polymerization reaction. After polymerization was complete, a 1 N aqueous NaOH solution was added to the collected reaction mixture to deash the catalyst residue. Furthermore, the reaction mixture was washed five times with a large amount of water, and then the solvent and unreacted polymerization components were removed under reduced pressure using an evaporator to obtain the reaction product.

[0091] [Second process] 100 g of the reaction product was dissolved in 400 g of acetone, a good solvent, and then added to 800 g of methanol while stirring to precipitate the reaction product. Next, The reaction product was filtered off by suction filtration, washed with a mixed solvent (acetone / methanol = 1 / 2 (by weight)), and then dried under reduced pressure at 100°C for 10 hours. This yielded a tire tackifier, which is a copolymer of isopropenyltoluene and the C5 fraction.

[0092] Manufacturing Example 2 (Isopropenyltoluene Homopolymer) A tire tackifier (homopolymer of isopropenyltoluene) was obtained based on the same procedure as in Manufacturing Example 1. However, the polymerization component was changed to isopropenyltoluene alone.

[0093] Manufacturing Comparison Example 1 (Homopolymer of α-methylstyrene) A tire tackifier (a homopolymer of α-methylstyrene) was obtained based on the same procedure as in Manufacturing Example 1. However, the polymerization component was changed to α-methylstyrene only. Also, the second step was omitted. Furthermore, in the first step, the supply rate of the Friedel-Crafts catalyst was changed to 90 ml / hour.

[0094] Manufacturing Comparative Example 2 (Copolymer of isopropenyltoluene and C5 fraction) A tire tackifier (a copolymer of isopropenyltoluene and the C5 fraction) was obtained based on the same procedure as in Manufacturing Example 1. However, the second step was omitted.

[0095] Manufacturing Comparative Example 3 (Isopropenyltoluene Homopolymer) A tire tackifier (homopolymer of isopropenyltoluene) was obtained based on the same procedure as in Manufacturing Example 2. However, the second step was omitted.

[0096] Manufacturing Comparative Example 4 (Copolymer of isopropenyltoluene and C5 fraction) A tire tackifier (a copolymer of isopropenyltoluene and the C5 fraction) was obtained based on the same procedure as in Manufacturing Example 1. However, the second step was omitted. In addition, the supply rate of the Friedel-Crafts catalyst in the first step was changed to 56 ml / hour.

[0097] Manufacturing Comparative Example 5 (Copolymer of isopropenyltoluene and C5 fraction) A tire tackifier (a copolymer of isopropenyltoluene and the C5 fraction) was obtained based on the same procedure as in Manufacturing Example 1. However, the second step was omitted. In addition, the supply rate of the Friedel-Crafts catalyst in the first step was changed to 90 ml / hour.

[0098] Manufacturing Comparative Example 6 (Copolymer of isopropenyltoluene and C5 fraction) A tire tackifier (polymer of isopropenyltoluene and C5 fraction) was obtained based on the same procedure as in Manufacturing Example 1, except that the second step was omitted. In the first step, the supply rate of the Friedel-Crafts catalyst was changed to 65 ml / hour. Also, in the first step, the polymerization temperature was changed to 20°C.

[0099] Manufacturing Comparative Example 7 (Isopropenyltoluene and indene copolymer) A tire tackifier (polymer of isopropenyltoluene and indene) was obtained based on the same procedure as in Manufacturing Example 1, except that the second step was omitted. In the first step, the supply rate of the Friedel-Crafts catalyst was changed to 120 ml / hour. Also in the first step, the polymerization components were changed to isopropenyltoluene and indene (isopropenyltoluene / indene = 60 / 40 (mass ratio)).

[0100] <Preparation of rubber composition for tires> Examples 1, 2, and Comparative Examples 1-8 Based on the information in Table 2, the rubber component and tire tackifier were blended and kneaded using a Laboplast Mill [Model 4C150, manufactured by Toyo Seiki Seisakusho Co., Ltd.] at a temperature of 160°C and a rotor speed of 40 rpm for approximately 5 minutes. This prepared a tire rubber composition.

[0101] <Rating> [Constituent units of each component] The constituent units of each component in the tire tackifier (polymer) of each manufacturing example and each manufacturing comparative example are determined based on the following conditions: 13 The results were obtained by analyzing the 1C-NMR spectrum. The results are shown in Table 1. {conditions} Equipment: Bruker BioSpin AVANCE III cryo-500 nuclear magnetic resonance spectrometer Measured nucleus: 13C (125MHz) Measurement mode: Single-pulse proton broadband decoupling Pulse width: 45° (5.00 μsec) Points: 64k Measurement range: 250 ppm (-55 to 195 ppm) Repeat time: 5.5 seconds Total number of times: 128 Measurement solvent: Orthodichlorobenzene / benzene-d6 (4 / 1 (volume ratio)) Sample concentration: 60 mg / 0.6 mL Measurement temperature: 120℃ Window function: exponential (BF: 1.0Hz) Chemical shift criterion: δδ signal 29.73 ppm

[0102] [Softening point] The tire tackifiers (polymers) for each manufacturing example and each manufacturing comparison were measured using the ring-sphere method in accordance with JIS K2207. The results are shown in Table 1.

[0103] [Number-average molecular weight (Mn), weight-average molecular weight (Mw), z-average molecular weight (Mz), dispersion (Mw / Mn), and content of compounds with a molecular weight of 500 or less in standard polystyrene equivalent, measured by gel permeation chromatography (GPC)] For each manufacturing example and comparative example of tire tackifiers (polymers), the number-average molecular weight (Mn), weight-average molecular weight (Mw), and z-average molecular weight (Mz) in standard polystyrene equivalent were measured by gel permeation chromatography (GPC) based on the following measurement conditions, and the Mw / Mn ratio was calculated. Furthermore, the content of compounds with a molecular weight of 500 or less in polystyrene equivalent was calculated by integrating the obtained molecular weight distribution. The results are shown in Table 1. In addition, the gel permeation chromatograms of the tire tackifiers for manufacturing example 1 and manufacturing comparative example 2 are shown in Figure 1. {Measurement conditions} Equipment: GPC HLC-8320 (manufactured by Tosoh Corporation) Solvent: Tetrahydrofuran Columns: TSKgel G7000 x 1, TSKgel G4000 x 2, TSKgel G2000 x 1 (all manufactured by Tosoh Corporation) Flow rate: 1.0ml / min Sample: 20 mg / mL tetrahydrofuran solution Column temperature: 40℃ Detector: Differential refractive index detector Injection volume: 50μl

[0104] [viscoelasticity] (Preparation of test specimens) A predetermined amount of the tire rubber composition for each example and comparative example was filled into a SUS mold. Using a manual hot press (PEWR-30, manufactured by Shinto Metal Industries Co., Ltd.) set to a heating plate of 150°C, the mixture was pressurized at a gauge pressure of 9 MPa for 4 minutes. Then, it was transferred to a cooling plate set to 20°C and compressed at a gauge pressure of 9 MPa for 3 minutes. This produced a measuring press sheet measuring 65 mm in length, 65 mm in width, and 2 mm in thickness. Next, test pieces were prepared by punching out pieces with a width of 3 mm from the measuring press sheet.

[0105] (tanδ peak intensity and tanδ peak temperature) Using a rheometer (DVA-225, manufactured by IT Measurement & Control Co., Ltd.), the tanδ peak temperature and tanδ peak value were measured on the test specimens under the conditions of tensile mode, frequency of 1 Hz, strain setting of 0.05%, and heating rate of 3 °C / min, in a temperature dispersion from -100 to 200 °C. The results are shown in Table 2.

[0106] (Ratio of tanδ peak intensity to Comparative Example 2) Furthermore, the ratio of the tanδ peak intensity of each example and each comparative example ([tanδ peak intensity of each example and each comparative example] / [tanδ peak intensity of Comparative Example 2] × 100) was calculated, with the tanδ peak intensity of Comparative Example 2 set to 100. The results are shown in Table 2. It can be seen that the higher the numerical value of the above peak intensity ratio, the better the wet grip performance of the tire obtained using this tire rubber composition. In addition, the wet grip performance was evaluated based on the following criteria. The results are shown in Table 2. {standard} A: The ratio of the above peak intensities was 90% or higher. B: The ratio of the above peak intensities was between 80% and 90%. C: The ratio of the above peak intensities was less than 80%.

[0107] (Shift value of tanδ peak temperature compared to Comparative Example 1) The shift value of the tanδ peak temperature relative to Comparative Example 1 ([tanδ peak temperature of each example and each comparative example] - [tanδ peak temperature of Comparative Example 1]) was calculated. A higher shift value indicates superior dispersibility of the tire tackifier. Furthermore, improved dispersibility of the tire tackifier can inhibit the movement of the rubber during dynamic deformation of the tire, thereby increasing energy loss and improving wet grip performance.

[0108] (Ratio of the tanδ peak temperature shift value to the tanδ peak temperature shift value in Comparative Example 2) The tanδ peak temperature shift value of Comparative Example 2 was set to 100, and the ratio of the tanδ peak temperature shift values ​​of each example and each comparative example ([tanδ peak temperature shift value of each example and each comparative example] / [tanδ peak temperature shift value of Comparative Example 2] × 100) was calculated. The results are shown in Table 2. It can be seen that the higher the numerical value of the above shift value ratio, the better the wet grip performance of the tire obtained using this tire rubber composition. Furthermore, the wet grip performance was evaluated based on the following criteria. The results are shown in Table 2. {standard} A: The ratio of the above shift values ​​was 140% or higher. B: The ratio of the above shift values ​​was between 120% and 140%. C: The ratio of the above shift values ​​was less than 120%.

[0109] (Tensile breaking strength) Dumbbell-shaped test specimens (Type 6) were punched out from the measuring press sheet prepared in the above test specimen preparation process. Tensile tests were then conducted in accordance with JIS K6251 under conditions of a chuck distance of 20.0 mm and a test speed of 500 mm / min, and the tensile breaking strength (MPa) was measured. The results are shown in Table 2.

[0110] (Ratio of tensile fracture strength to Comparative Example 2) The tensile breaking strength of Comparative Example 2 was set to 100, and the ratio of the tensile breaking strengths of each example and each comparative example ([tensile breaking strength of each example and each comparative example] / [tensile breaking strength of Comparative Example 2] × 100) was calculated. The results are shown in Table 2. It can be seen that the higher the ratio of the above tensile breaking strengths, the better the fracture resistance of the tire obtained using this tire rubber composition. Furthermore, fracture resistance was evaluated based on the following criteria. The results are shown in Table 2. {standard} A: The ratio of tensile breaking strength was 105% or higher. B: The ratio of tensile breaking strength was 100% or more. C: The ratio of tensile breaking strength was less than 100%.

[0111] [Table 1]

[0112] [Table 2]

Claims

1. It contains constituent units derived from isopropenyltoluene, The number-average molecular weight, measured by gel permeation chromatography (GPC) and converted to standard polystyrene, is between 800 and 4000. A tire tackifier having a molecular weight distribution dispersion (weight-average molecular weight / number-average molecular weight) of less than 1.

50.

2. The tackifier for tires according to claim 1, comprising constituent units derived from the C5 fraction.

3. The tackifier for tires according to claim 1, wherein the content of constituent units derived from isopropenyltoluene is 97 mol% or more.

4. The tackifier for tires according to claim 1, wherein the content of compounds with a molecular weight of 500 or less on a standard polystyrene basis, as measured by gel permeation chromatography (GPC), is 12.0% or less.

5. A tire tackifier according to any one of claims 1 to 4, A rubber composition for tires, comprising rubber components.

6. A tire, which is a vulcanized product of the tire rubber composition described in claim 5.

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