Rubber composition for tires and tires

Abstract

To provide a rubber composition for tire that is excellent in processability and can exhibit excellent wear resistance in a tire.SOLUTION: Provided is a rubber composition for tire that contains a rubber component, a carbon black and glycerin fatty acid ester, and in which, characterized, the carbon black has a cetyltrimethylammonium bromide adsorption specific surface area (CTAB) of 130 m2 / g or more, a ratio (CTAB / IA) of the CTAB (m2 / g) to the iodine adsorption amount (IA) (mg / g) of 0.92 or more and 1.06 or less, and a hydrogen emission amount of 3500 mass ppm or more and 4800 mass ppm or less.SELECTED DRAWING: None

Description

Technical Field

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

Background Art

[0002] Particularly, wear resistance is required for the tread of a tire, and performance is improved by optimizing the materials used for manufacturing the tread.

[0003] For example, Patent Document 1 discloses that a pneumatic tire having excellent low rolling resistance and wear resistance can be obtained by using, for the tread, a rubber composition in which a butadiene polymer having a relatively high cis content modified with a predetermined modifier and carbon black having a nitrogen adsorption specific surface area exceeding 100 m 2 / g are combined.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, the rubber composition described in Patent Document 1 has room for improvement in terms of further improving wear resistance, and also has a tendency to have high viscosity, so improvement in processability is also desired.

[0006] Therefore, an object of the present invention is to provide a rubber composition for tires that is excellent in processability and can exhibit excellent wear resistance in tires. Another object of the present invention is to provide a tire having excellent wear resistance.

Means for Solving the Problems

[0007] The gist configuration of the present invention for solving the above problems is as follows.

[0008] The rubber composition for tires of the present invention contains a rubber component, carbon black, and glycerin fatty acid ester, wherein the carbon black has a cetyltrimethylammonium bromide adsorption specific surface area (CTAB) of 130 m 2 / g or more, a ratio (CTAB / IA) of the CTAB (m 2 / g) to the iodine adsorption amount (IA) (mg / g) of 0.92 or more and 1.06 or less, and a hydrogen evolution amount of 3500 mass ppm or more and 4800 mass ppm or less, and is characterized by this. The rubber composition for tires of the present invention is excellent in processability and can exhibit excellent abrasion resistance in tires.

[0009] In the rubber composition for tires of the present invention, it is preferable that the rubber component includes a modified butadiene rubber. In this case, the abrasion resistance can be further improved.

[0010] In the rubber composition for tires of the present invention, from the viewpoint of further improving the abrasion resistance, the ratio of the modified butadiene rubber in the rubber component is preferably 5 mass% or more.

[0011] In the rubber composition for tires of the present invention, it is preferable that the rubber component further includes an unmodified butadiene rubber. In this case, the abrasion resistance can be further improved.

[0012] In the rubber composition for tires of the present invention, from the viewpoint of further improving the abrasion resistance, the ratio of the unmodified butadiene rubber in the rubber component is preferably 10 mass% or more.

[0013] In the rubber composition for tires of the present invention, from the viewpoints of cost and workability during rubber kneading, etc., the ratio of the modified butadiene rubber in the rubber component is preferably 30 mass% or less.

[0014] In the rubber composition for tires of the present invention, from the viewpoint of further improving the abrasion resistance and maintaining other properties such as low loss property and processability well, the CTAB of the carbon black is 135 m 2 / g or more and 150 m 2 / g or less.

[0015] In the rubber composition for tires of the present invention, it is preferable that the content of the carbon black is 40 parts by mass or more and 70 parts by mass or less with respect to 100 parts by mass of the rubber component. In this case, the abrasion resistance can be effectively improved, and other properties such as low loss property and processability can be maintained well.

[0016] In the rubber composition for tires of the present invention, it is preferable that the content of the glycerin fatty acid ester is 0.1 part by mass or more and 10 parts by mass or less with respect to 100 parts by mass of the rubber component. In this case, the processability can be further improved sufficiently, and the abrasion resistance can be maintained well.

[0017] In the rubber composition for tires of the present invention, the glycerin fatty acid ester contains a monoester component, and it is preferable that the ratio of the monoester component in the glycerin fatty acid ester is 50% by mass or more and 100% by mass or less. In this case, the abrasion resistance and / or processability can be further enhanced, and it is also preferable from the viewpoint of production.

[0018] In the rubber composition for tires of the present invention, from the same viewpoint as above, it is preferable that the ratio of the monoester component in the glycerin fatty acid ester is 85% by mass or more.

[0019] In the rubber composition for tires of the present invention, it is preferable that the rubber component contains natural rubber. In this case, the mechanical strength as a rubber article can be enhanced.

[0020] The rubber composition for tires of the present invention is suitably used for tire treads.

[0021] The tire of the present invention is characterized in that the above-described rubber composition for a tire is used for the tread. The tire of the present invention is excellent in wear resistance.

Effect of the Invention

[0022] According to the present invention, it is possible to provide a rubber composition for a tire that is excellent in processability and can exhibit excellent wear resistance in a tire. Further, according to the present invention, it is possible to provide a tire excellent in wear resistance.

Mode for Carrying Out the Invention

[0023] Hereinafter, embodiments of the present invention will be described. However, these descriptions are for the purpose of exemplifying the present invention and do not limit the present invention in any way.

[0024] (Rubber composition for a tire) The rubber composition for a tire according to an embodiment of the present invention (hereinafter sometimes referred to as "the rubber composition of the present embodiment") contains at least a rubber component, carbon black, and glycerin fatty acid ester. Further, the carbon black used in the present embodiment has, as a first physical property, a cetyltrimethylammonium bromide adsorption specific surface area (CTAB) of 130 m 2 / g or more, and as a second physical property, a ratio (CTAB / IA) of the CTAB (m 2 / g) to the iodine adsorption amount (IA) (mg / g) of 0.92 or more and 1.06 or less, and further, as a third physical property, a hydrogen release amount of 3500 mass ppm or more and 4800 mass ppm or less. Since the rubber composition of the present embodiment contains carbon black having the above physical properties, it can exhibit high wear resistance. Note that the carbon black having the above physical properties simultaneously is substantially new. Further, since the rubber composition of the present embodiment contains glycerin fatty acid ester, it can favorably maintain the processability that may be deteriorated by the inclusion of the above carbon black.

[0025] Since the rubber composition of this embodiment can exhibit excellent abrasion resistance as described above, it is suitably used for tire treads.

[0026] <Rubber component> Examples of the rubber component contained in the rubber composition of this embodiment include butadiene rubber (BR), isoprene rubber (IR), styrene-butadiene rubber (SBR), acrylonitrile-butadiene rubber (NBR), chloroprene rubber (CR), ethylene-propylene rubber (EPM), ethylene-propylene-diene rubber (EPDM), polysulfide rubber, silicone rubber, fluororubber, urethane rubber, and the like. These rubber components may be used alone or in combination of two or more. Further, these rubber components may be modified.

[0027] In this embodiment, it is preferable that the rubber component includes modified butadiene rubber (also referred to as modified BR). The modified butadiene rubber is a butadiene rubber having one or more functional groups having atoms other than carbon and hydrogen. Since the modified butadiene rubber exhibits excellent reinforcing properties by chemically bonding to carbon black, the abrasion resistance can be further improved. The modified butadiene rubber may be used alone or in combination of two or more.

[0028] The modified butadiene rubber may have the above functional group at the terminal or in the main chain. Further, the modified butadiene rubber can be obtained, for example, by modifying butadiene rubber (unmodified butadiene rubber) with a modifier.

[0029] Examples of atoms other than carbon and hydrogen include nitrogen atoms, oxygen atoms, sulfur atoms, metalloid atoms, and metal atoms. The functional group preferably has one or more atoms selected from these. Examples of metalloid atoms include boron, silicon, germanium, arsenic, antimony, and tellurium. Among these, one or more atoms selected from boron, silicon, and germanium are more preferable, and silicon is particularly preferable. Examples of metal atoms include tin, titanium, zirconium, bismuth, and aluminum. Among these, one or more atoms selected from tin and titanium are more preferable, and tin is particularly preferable.

[0030] In the rubber composition of the present embodiment, from the viewpoint of more sufficiently improving the abrasion resistance, the proportion of the modified butadiene rubber in the rubber component is preferably 5% by mass or more, more preferably 8% by mass or more, and still more preferably 10% by mass or more. On the other hand, the upper limit of the proportion of the modified butadiene rubber in the rubber component is not particularly limited, but from the viewpoints of cost and workability during rubber kneading, etc., it is preferably 30% by mass or less.

[0031] Further, the rubber component preferably contains unmodified butadiene rubber (unmodified BR, or simply referred to as BR) together with the modified butadiene rubber. As described above, the modified butadiene rubber contributes to the improvement of abrasion resistance, but can deteriorate the filler dispersibility on the micrometer order. However, by using the modified butadiene rubber and the unmodified butadiene rubber in combination, the filler dispersibility can be further improved, and the reinforcing property and the filler dispersibility can be made compatible in a high dimension, and as a result, the abrasion resistance can be further improved. The unmodified butadiene rubber may be used alone or in combination of two or more.

[0032] In the rubber composition of the present embodiment, the proportion of unmodified butadiene rubber in the rubber component is preferably 10% by mass or more, more preferably 20% by mass or more, from the viewpoint of more sufficiently improving the abrasion resistance. On the other hand, the upper limit of the proportion of unmodified butadiene rubber is not particularly limited, but is preferably 40% by mass or less, more preferably 35% by mass or less, from the viewpoint of maintaining the basic abrasion resistance improvement effect by the modified butadiene rubber.

[0033] In the rubber composition of the present embodiment, the proportion of the modified butadiene rubber in the total of the modified butadiene rubber and the unmodified butadiene rubber is preferably 10% by mass or more and 50% by mass or less. In this case, the effect of improving the abrasion resistance can be obtained more sufficiently. From the same viewpoint, the proportion of the modified butadiene rubber in the total of the modified butadiene rubber and the unmodified butadiene rubber is preferably 15% by mass or more, more preferably 20% by mass or more, and preferably 40% by mass or less.

[0034] Further, the rubber composition of the present embodiment preferably contains natural rubber (NR). In other words, the rubber component used in the present embodiment preferably includes natural rubber. In this case, the mechanical strength as a rubber article can be increased.

[0035] In the rubber composition of the present embodiment, the proportion of natural rubber in the rubber component is preferably 30% by mass or more and 70% by mass or less. If the proportion of natural rubber in the rubber component is 30% by mass or more, the mechanical strength can be sufficiently increased. Further, if the proportion of natural rubber in the rubber component is 70% by mass or less, the effect of using rubber components other than natural rubber (for example, modified butadiene rubber, unmodified butadiene rubber, etc.) in combination can be sufficiently exhibited, and the abrasion resistance can be further improved.

[0036] In addition, the rubber composition of the present embodiment may or may not contain other rubber components other than the modified butadiene rubber, unmodified butadiene rubber, and natural rubber described above. However, in the rubber composition of the present embodiment, the proportion of the other rubber components in the rubber components is preferably 20% by mass or less, more preferably 10% by mass or less, still more preferably 5% by mass or less, and particularly preferably 0% by mass (that is, does not contain other rubber components).

[0037] <Carbon black> As a first physical property, the carbon black used in the present embodiment requires that the cetyltrimethylammonium bromide adsorption specific surface area (CTAB) is 130 m 2 / g or more. Since the carbon black has a CTAB of 130 m 2 / g or more, it can enhance the reinforcing property of the rubber component and thus contribute to the improvement of abrasion resistance. Further, from the viewpoint of further improving the abrasion resistance, the CTAB of the carbon black is preferably 135 m 2 / g or more, and from the viewpoint of maintaining other performances such as low loss property and processability well, it is preferably 150 m 2 / g or less. The CTAB of the carbon black is measured in accordance with JIS K6217-3. The adjustment of the CTAB of the carbon black is not limited, but can be performed, for example, by controlling various conditions such as raw material introduction conditions, air introduction conditions, fuel introduction conditions, and cooling water introduction conditions when manufacturing the carbon black.

[0038] The carbon black preferably has an iodine adsorption amount (IA) of 150 mg / g or less. If the IA of the carbon black is 150 mg / g or less, predetermined activation on the carbon black surface is preferably performed, and the interactivity with the modified butadiene rubber and / or unmodified butadiene rubber mixed as the rubber component can be improved well. Further, from the viewpoint of maintaining other performances such as low loss property and processability well, the IA of the carbon black is preferably 130 mg / g or more. Note that the iodine adsorption (IA) of carbon black is measured in accordance with JIS K6217-1. The adjustment of the IA of carbon black is not limited, but can be performed, for example, by controlling various conditions such as raw material introduction conditions, air introduction conditions, fuel introduction conditions, and cooling water introduction conditions during the production of carbon black.

[0039] In addition, as the second physical property, the carbon black requires that the ratio of CTAB (m 2 / g) to the iodine adsorption amount (IA) (mg / g) (CTAB / IA) is 0.92 or more and 1.06 or less. If CTAB / IA is less than 0.92, the abrasion resistance may deteriorate. Also, if CTAB / IA exceeds 1.06, the processability deteriorates, and as a result, the abrasion resistance may deteriorate. Further, from the viewpoint of further improving the abrasion resistance, the CTAB / IA of the carbon black is preferably 0.95 or more and preferably 1.05 or less.

[0040] Furthermore, as the third physical property, the carbon black requires that the hydrogen release amount is 3500 mass ppm or more and 4800 mass ppm or less. If the hydrogen release amount is less than 3500 mass ppm, the predetermined activation of the carbon black surface and, as a result, the interactivity of the rubber component become insufficient, and as a result, the abrasion resistance may deteriorate. Also, if the hydrogen release amount exceeds 4800 mass ppm, the abrasion resistance may deteriorate due to excessive hydrogen. Further, from the viewpoint of further improving the abrasion resistance, the hydrogen release amount of the carbon black is preferably 3700 mass ppm or more, preferably 4500 mass ppm or less, and more preferably 4300 mass ppm or less. Note that the hydrogen release amount of carbon black refers to the amount of hydrogen gas released when heated at 2000 °C for 15 minutes in an argon atmosphere and is measured using a hydrogen analyzer. The adjustment of the hydrogen release amount of carbon black is not limited, but can be performed, for example, by controlling various conditions such as raw material introduction conditions, air introduction conditions, fuel introduction conditions, and cooling water introduction conditions during the production of carbon black.

[0041] The above carbon black preferably has a dibutyl phthalate oil absorption (DBP) of 130 cm 3 / 100 g or more and 150 cm 3 / 100 g or less. If the DBP is 130 cm 3 / 100 g or more, the abrasion resistance is further improved, and if it is 150 cm 3 / 100 g or less, the processability can be maintained well.

[0042] The manufacturing method of the above carbon black is not particularly limited as long as it can have desired physical properties. However, it is extremely difficult to adjust each of the physical properties such as CTAB, IA, and hydrogen release amount in carbon black alone. The carbon black that can be used in this embodiment can be manufactured, for example, by appropriately adjusting based on the manufacturing conditions of the examples described later.

[0043] The content of the above carbon black in the rubber composition of this embodiment is preferably 40 parts by mass or more and 70 parts by mass or less with respect to 100 parts by mass of the above rubber component. If the content of the above carbon black is 40 parts by mass or more, the interactivity with the rubber component is sufficiently increased, and the abrasion resistance can be effectively improved. Also, if the content of the above carbon black is 70 parts by mass or less, other performances such as low loss property and processability can be maintained well. From the same viewpoint, the content of the above carbon black in the rubber composition is more preferably 45 parts by mass or more, and more preferably 60 parts by mass or less with respect to 100 parts by mass of the above rubber component.

[0044] The rubber composition of this embodiment may or may not contain other carbon blacks other than the carbon black having the above-described physical properties. Examples of other carbon blacks include carbon blacks that satisfy only two of the above-described first physical property, second physical property, and third physical property, carbon blacks that satisfy only one of them, or carbon blacks that satisfy none of them. However, from the viewpoint of more surely obtaining the effect of improving the wear resistance peculiar to the present invention, in the rubber composition of this embodiment, the proportion of other carbon blacks in all carbon blacks is preferably 20% by mass or less, more preferably 10% by mass or less, still more preferably 5% by mass or less, and particularly preferably 0% by mass (that is, does not contain other carbon blacks).

[0045] <Glycerin fatty acid ester> The rubber composition of this embodiment contains a glycerin fatty acid ester. Here, the glycerin fatty acid ester is an ester of glycerin and one or more fatty acids, and more specifically, a compound in which at least one of the three OH groups of glycerin and the COOH group of the fatty acid are ester-bonded. These glycerin fatty acid esters may be used alone or in combination of two or more.

[0046] The glycerin fatty acid ester is not particularly limited, but includes a glycerin fatty acid monoester (monoester component) formed by esterifying one molecule of glycerin and one molecule of fatty acid, a glycerin fatty acid diester (diester component) formed by esterifying one molecule of glycerin and two molecules of fatty acid, a glycerin fatty acid triester (triester component) formed by esterifying one molecule of glycerin and three molecules of fatty acid, and the like. These monoester components, diester components, and triester components may each be used alone or in combination of two or more.

[0047] In particular, in the present embodiment, the glycerin fatty acid ester contains a monoester component (glycerin fatty acid monoester), and the proportion of the monoester component in the glycerin fatty acid ester is preferably 50% by mass or more and 100% by mass or less. In this case, the wear resistance and / or processability can be further improved, and it is also preferable from the viewpoint of production. From the same viewpoint, the proportion of the monoester component in the glycerin fatty acid ester is more preferably 85% by mass or more. The upper limit of the proportion of the monoester component in the glycerin fatty acid ester is not particularly limited, but can be 99% by mass or less, 98% by mass or less. The proportions (mass %) of the monoester component, diester component, and triester component in the glycerin fatty acid ester can be measured according to the method described in International Publication No. 2014 / 098155. Specifically, it can be measured by gel permeation chromatography (GPC).

[0048] From the viewpoints of the processability and wear resistance of the rubber composition, the fatty acid used as a raw material for the glycerin fatty acid ester preferably has 8 to 22 carbon atoms, more preferably 12 to 18 carbon atoms, still more preferably 14 to 18 carbon atoms, and even more preferably 16 or 18 carbon atoms.

[0049] The constituent fatty acid of the glycerin fatty acid ester may be linear or branched, but is preferably linear. It may be a saturated fatty acid or an unsaturated fatty acid, but is preferably a saturated fatty acid.

[0050] Specific examples of the constituent fatty acid of the glycerin fatty acid ester include caprylic acid, pelargonic acid, capric acid, lauric acid, myristic acid, palmitic acid, stearic acid, isostearic acid, oleic acid, linoleic acid, linolenic acid, arachidonic acid, behenic acid, etc. Among these, lauric acid, myristic acid, palmitic acid, and stearic acid are preferable, and palmitic acid and stearic acid are more preferable.

[0051] As raw materials for fatty acids, those obtained by hydrolyzing oils and fats such as vegetable oils and animal fats, and those obtained by hydrogenating or de-hydrogenating those oils and fats or hydrolyzed fatty acids can be used. The oil and fat raw materials are not particularly limited, and examples include vegetable oils and animal fats. More specifically, palm oil, soybean oil, olive oil, cottonseed oil, coconut oil, palm kernel oil, beef tallow, lard, fish oil, etc. can be used.

[0052] The glycerin fatty acid ester may be obtained by any method such as an esterification reaction of glycerin and a fatty acid, a method of obtaining it by hydrolyzing a glycerin fatty acid triester such as natural oil and fat, or a method of transesterifying a glycerin fatty acid triester such as natural oil and fat with a fatty acid. The method for obtaining the glycerin fatty acid ester is not particularly limited, and known methods can be used. From the viewpoint of productivity, a method of obtaining it by an esterification reaction of glycerin and a fatty acid is preferable.

[0053] The content of the glycerin fatty acid ester in the rubber composition of the present embodiment is preferably 0.1 part by mass or more and 10 parts by mass or less with respect to 100 parts by mass of the rubber component. If the content is 0.1 part by mass or more, the processability can be more sufficiently improved, and if it is 10 parts by mass or less, the abrasion resistance can be kept good. From the same viewpoint, the content of the glycerin fatty acid ester is more preferably 1 part by mass or more, and more preferably 5 parts by mass or less.

[0054] <Other Components> The rubber composition of the present embodiment may contain a filler other than carbon black. Examples of the filler other than carbon black include silica, aluminum hydroxide, clay, alumina, talc, mica, kaolin, glass balloon, glass beads, calcium carbonate, magnesium carbonate, magnesium hydroxide, magnesium oxide, titanium oxide, potassium titanate, barium sulfate, etc. However, from the viewpoint of more surely obtaining the effect of improving the abrasion resistance peculiar to the present invention, it is preferable that the rubber composition of the present embodiment does not contain a filler other than carbon black.

[0055] In addition, the rubber composition of the present embodiment can contain compounding agents commonly used in the rubber industry, such as crosslinking agents (vulcanizing agents) like sulfur, crosslinking accelerators (vulcanization accelerators), process oils, scorch inhibitors, zinc white, and stearic acid, etc., as long as the object of the present invention is not deviated from, and can be appropriately selected and contained. As these compounding agents, commercially available products can be preferably used. And the rubber composition can be produced by compounding a carbon black and a glycerin fatty acid ester with the rubber component, and various compounding agents appropriately selected as necessary, followed by kneading, heating, extrusion, etc.

[0056] The method for preparing the rubber composition of the present embodiment is not particularly limited, and known methods can be used. For example, it can be obtained by kneading each component including a predetermined rubber component, carbon black, and glycerin fatty acid ester using a kneader such as a Banbury mixer, rolls, or an internal mixer. Also, components other than the crosslinking accelerator and the crosslinking agent can be mixed in the non-production (non-pro) stage, and the crosslinking accelerator and the crosslinking agent can be compounded and mixed in the production (pro) stage to prepare the rubber composition.

[0057] The rubber composition of the present embodiment can be crosslinked or vulcanized. The conditions for crosslinking or vulcanizing the rubber composition can be adjusted as appropriate. For example, the temperature can be 120 to 200 °C and the heating time can be 1 minute to 900 minutes.

[0058] (Tire) A tire according to an embodiment of the present invention is characterized in that the rubber composition of the present embodiment is used for the tread. Since the tread of the above tire is made of the rubber composition of the present embodiment, it has excellent wear resistance.

[0059] As a method for manufacturing a tire, it is not particularly limited except for applying the rubber composition of the present embodiment to the tread, and known methods can be used.

Examples

[0060] Hereinafter, the present invention will be described in more detail with reference to examples. However, these examples are for the purpose of exemplifying the present invention and do not limit the present invention in any way.

[0061] (Preparation of Carbon Black) Carbon black CB1 was prepared. The control of the physical properties of carbon black was carried out by changing various conditions (raw material introduction amount, air introduction amount, temperature, pressure, reaction time, etc.) as shown in Table 1. In addition, as carbon black CB2, "VULCAN 7HJ" (N234) manufactured by Cabot Japan Co., Ltd. was prepared.

[0062]

Table 1

[0063] For the prepared CB1 and CB2, in accordance with JIS K6217-3, the cetyltrimethylammonium bromide adsorption specific surface area (CTAB) [m 2 / g] was measured, and in accordance with JIS K6217-1, the iodine adsorption amount (IA) [mg / g] was measured. Further, for the prepared CB1 and CB2, using a hydrogen analyzer (manufactured by HORIBA, "EMGA"), the amount of hydrogen gas released (hydrogen release amount) when heated at 2000 °C for 15 minutes in an argon atmosphere was measured. The results are shown in Table 2 together with the calculated values of CTAB / IA.

[0064]

Table 2

[0065] (Preparation of Modified Butadiene Rubber (HMI-BR)) Into a dried and nitrogen-substituted pressure-resistant glass container of about 900 mL, 283 g of cyclohexane, 50 g of 1,3-butadiene, 0.0057 mmol of 2,2-ditetrahydrofurylpropane, and 0.513 mmol of hexamethyleneimine (HMI-BR) were added. After further adding 0.57 mmol of n-butyllithium (BuLi), polymerization was carried out in a 50 °C warm water bath equipped with a stirrer for 4.5 hours. The polymerization conversion rate at this time was almost 100%. Next, 0.100 mmol of tin tetrachloride was quickly added to this polymerization reaction system as a modifier (coupling agent), and the mixture was further stirred at 50 °C for 30 minutes to carry out a modification reaction. Then, 0.5 mL of an isopropanol solution of 2,6-di-t-butyl-p-cresol (BHT) (BHT concentration: 5% by mass) was added to the polymerization reaction system to stop the reaction, and it was further dried according to a conventional method to obtain a modified butadiene rubber (HMI-BR) having tin atoms. Regarding the obtained HMI-BR, 1 When the amount of vinyl bonds in the butadiene portion was measured from the integration ratio of the 1H-NMR spectrum, it was 14%. When the glass transition temperature (Tg) was determined from the inflection point of the DSC curve, it was -95 °C. When the coupling rate was determined from the ratio of the peak area on the highest molecular weight side to the total area of the molecular weight distribution curve by gel permeation chromatography (GPC), it was 65%.

[0066] (Preparation of Rubber Composition) Next, a rubber composition was prepared by thoroughly kneading according to the formulation shown in Table 3. Using the obtained rubber composition, abrasion resistance was evaluated according to the following procedure.

[0067] <Abrasion Resistance (Field Test)> The prepared rubber composition was used for the tread member, and vulcanization was carried out as appropriate to produce a pneumatic tire for trucks and buses with a size of 195 / 85R16. The obtained tire was mounted on a small truck and driven on a public road for 8000 km, and then the abrasion amount was measured from the change in the main groove depth of the tire. Then, taking the reciprocal of the abrasion amount of Comparative Example 1 as 100, the abrasion resistance in each example was evaluated by an index. The results are shown in Table 3. The larger the index value, the better the abrasion resistance.

[0068] <Storage elastic modulus G'> Using a viscoelasticity measuring device (trade name: RPA-2000, manufactured by Alpha Technologies), the storage elastic modulus (G') of the rubber composition was measured under the conditions of 130°C and 100% strain. Then, with the storage elastic modulus of Comparative Example 1 taken as 100, the storage elastic modulus in each example was evaluated exponentially. The results are shown in Table 3. The smaller the exponential value, the better the processability.

[0069]

Table 3

[0070] *1 NR: TSR#20 *2 Modified BR: Prepared modified butadiene rubber (HMI-BR) *3 Unmodified BR: Manufactured by Ube Industries, Ltd., "UBEPOL BR150L" *4 Glycerol fatty acid ester: Synthesized by replacing fatty acid from octanoic acid with the same molar amount of hardened fatty acid derived from palm oil according to the method described in Production Example 1 of International Publication No. 2014 / 098155, and further adjusted by molecular distillation (glycerol fatty acid ester composition) was used. The proportion of glycerol fatty acid monoester in the obtained glycerol fatty acid ester was 97% by mass. *5 Vulcanization accelerator CZ: N-cyclohexyl-2-benzothiazylsulfenamide, manufactured by Ouchi Shinko Chemical Industry Co., Ltd., "Nocceler CZ"

[0071] From Tables 1 to 3, it can be seen that the rubber composition of the example according to the present invention improves the processability while enhancing the abrasion resistance of the tire as compared with the rubber composition of the comparative example.

Industrial Applicability

[0072] According to the present invention, it is possible to provide a rubber composition for tires that is excellent in processability and can exhibit excellent abrasion resistance in tires. Further, according to the present invention, it is possible to provide a tire having excellent abrasion resistance.

Claims

1. A rubber composition containing a rubber component, carbon black, and glycerin fatty acid ester, The carbon black has a cetyltrimethylammonium bromide adsorption specific surface area (CTAB) of 130 m ２ / g or more, and the ratio (CTAB / IA) of the CTAB (m ２ / g) to the iodine adsorption amount (IA) (mg / g) is 0.92 or more and 1.06 or less, and the hydrogen release amount is 3500 mass ppm or more and 4800 mass ppm or less, wherein the rubber component includes a modified butadiene rubber having one or more functional groups containing nitrogen atoms, oxygen atoms, sulfur atoms, semi-metal atoms, and metal atoms, characterized in that it is a rubber composition for tires.

2. The rubber composition for tires according to claim 1, wherein the proportion of the modified butadiene rubber in the rubber component is 5% by mass or more.

3. The rubber composition for tires according to claim 1 or 2, wherein the rubber component further includes an unmodified butadiene rubber.

4. The rubber composition for tires according to claim 3, wherein the proportion of the unmodified butadiene rubber in the rubber component is 10% by mass or more.

5. The rubber composition for tires according to any one of claims 1 to 4, wherein the proportion of the modified butadiene rubber in the rubber component is 30% by mass or less.

6. The CTAB of the carbon black is 135 m ２ / g or more and 150 m ２ / g or less, and the rubber composition for tires according to any one of claims 1 to 5.

7. The rubber composition for tires according to any one of claims 1 to 6, wherein the content of the carbon black is 40 parts by mass or more and 70 parts by mass or less with respect to 100 parts by mass of the rubber component.

8. The rubber composition for tires according to any one of claims 1 to 7, wherein the content of the glycerin fatty acid ester is 0.1 part by mass or more and 10 parts by mass or less with respect to 100 parts by mass of the rubber component.

9. The rubber composition for tires according to any one of claims 1 to 8, wherein the glycerin fatty acid ester contains a monoester component, and the proportion of the monoester component in the glycerin fatty acid ester is 50% by mass or more and 100% by mass or less.

10. The rubber composition for tires according to claim 9, wherein the proportion of the monoester component in the glycerin fatty acid ester is 85% by mass or more.

11. The rubber composition for tires according to any one of claims 1 to 10, wherein the rubber component includes natural rubber.

12. The rubber composition for tires according to any one of claims 1 to 11, which is used for a tire tread.

13. A tire characterized in that the rubber composition for tires according to any one of claims 1 to 12 is used for the tread.

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