JP2024044764A - Rubber composition for tires and tires - Google Patents

Abstract

[Problem] When using recycled carbon black (recycled CB) in tire treads for tire recycling, heat generation and wet performance sufficient for practical use are required. [Solution] The above problem is solved by a rubber composition for tires, which contains diene rubber, silica, and recycled CB, in which the difference (ΔDBP) between the DBP oil absorption and the compressed DBP oil absorption (24M4DBP) of the recycled CB is less than 20 ml/100 g, N2SA/IA, which is the ratio of the nitrogen adsorption specific surface area N2SA to the iodine adsorption amount IA of the recycled CB, is 0.8 or more and less than 2.0, the proportion of SBR is 30 parts by mass or more per 100 parts by mass of diene rubber, and 40 to 150 parts by mass of silica and 1 to 10 parts by mass of recycled CB are blended with respect to 100 parts by mass of diene rubber. [Selected Figure] None

Description

The present invention relates to a rubber composition for tires and tires, and more specifically to a rubber composition for tires that can maintain sufficient heat generation and wet performance for practical use even when recycled carbon black is blended, and a tire using the same.

In recent years, with the increasing attention being paid to resource conservation and environmental protection, there is a demand for improving the recycling rate of tires as well. To address this issue, the use of recycled carbon black obtained by pyrolyzing used rubber products such as scrap tires (see, for example, Patent Documents 1 to 3 below) and recycled carbon black derived from non-petroleum raw materials has been proposed.
However, recycled carbon black contains impurities derived from the raw materials used in tires, such as reinforcing materials and tire cords, and/or impurities derived from the pyrolysis process during production. This causes problems such as a significant decrease in various tire performance characteristics, including heat generation and wet performance (braking performance on wet road surfaces).

Patent No. 6553959 JP 2012-1682 A Patent No. 6856781

The object of the present invention is therefore to provide a rubber composition for tires that can maintain sufficient heat generation and wet performance for practical use even when recycled carbon black is blended into the composition, and a tire using the same.

As a result of extensive research, the present inventors found that in tire rubber compositions containing diene rubber including styrene-butadiene copolymer rubber, silica, and recycled carbon black, the DBP oil absorption amount and compressed DBP of recycled carbon black were determined. The difference in oil absorption (24M4DBP) (ΔDBP) and the ratio of nitrogen adsorption specific surface area N ₂ SA (unit: m ² /g) to iodine adsorption amount IA (unit: mg/g) are adjusted to appropriate ranges _. The inventors have discovered that the above problems can be solved by setting the amounts of silica and recycled carbon black within specific ranges, and have completed the present invention.

That is, the present invention provides a rubber composition for tires, which contains a diene rubber including a styrene-butadiene copolymer rubber, silica, and recycled carbon black,
the difference (ΔDBP) between the DBP oil absorption and the compressed DBP oil absorption (24M4DBP) of the recycled carbon black is less than 20 ml/100 g;
the ratio of the nitrogen adsorption specific surface area _N2SA (unit: ^m2 /g) to the iodine adsorption amount IA (unit: mg/g) of the regenerated carbon black, _N2SA /IA, is in the range of 0.8 or more and less than 2.0;
The proportion of the styrene-butadiene copolymer rubber in 100 parts by mass of the diene rubber is 30 parts by mass or more,
The rubber composition for tires is characterized by comprising 100 parts by mass of the diene rubber, 40 to 150 parts by mass of silica, and 1 to 10 parts by mass of the recycled carbon black.
The present invention also provides a tire using the above rubber composition for tires.

As described above, recycled carbon black contains impurities derived from the raw materials of tires, such as reinforcing materials and tire cords, and/or impurities derived from the thermal decomposition process during manufacturing, which causes problems such as deterioration of heat generation and wet performance. One of the reasons for this is thought to be that the impurities contained in the recycled carbon black reduce the dispersibility of the filler added to the rubber composition. As a result of extensive research, the present inventors have found that the above problem can be solved by adopting recycled carbon black that satisfies the above ΔDBP and N ₂ SA/IA in specific ranges, even when the recycled carbon black contains impurities (e.g., ash).
As a result, according to the present invention, it is possible to provide a rubber composition for tires and a tire that can maintain practically sufficient heat build-up properties and wet performance even when recycled carbon black is blended therein.

The present invention will be explained in more detail below.

(Diene rubber)
The diene rubber used in the present invention contains styrene-butadiene copolymer rubber (SBR) as an essential component in order to maintain practically sufficient heat generation properties and wet performance. Note that SBR preferably occupies 30 parts by mass or more, preferably 50 parts by mass or more in 100 parts by mass of the diene rubber.
In addition to the SBR, the diene rubber may also include natural rubber (NR), isoprene rubber (IR), butadiene rubber (BR), acrylonitrile-butadiene copolymer rubber (NBR), ethylene- Propylene-diene terpolymer (EPDM) and the like can be used. These may be used alone or in combination of two or more.

Further, the SBR used in the present invention preferably has a functional group capable of interacting with silica.
Such SBR preferably has at its terminal a functional group derived from a compound that reacts with a silanol group on the silica surface, specifically, a hydroxy group, a carboxyl group, a carbonyl group, an aldehyde group, an epoxy group, an amino group, etc. Examples include a group, an amide group, a silyl group, an oxysilyl group, a silanol group, an isocyanate group, an isothiocyanate group, and the like.
SBR having a functional group capable of interacting with silica can be synthesized according to a known method, or a commercially available one can be appropriately employed. For example, examples of SBR modified with epoxy groups include NS616 manufactured by ZS Elastomer Co., Ltd., and examples of SBR modified with hydroxyl groups include TUFDENE E581 manufactured by Asahi Kasei Corporation.

(silica)
Examples of the silica used in the present invention include wet silica (hydrated silicic acid), dry silica (anhydrous silicic acid), calcium silicate, aluminum silicate, etc., and one of these may be used alone. , two or more types may be used in combination.
From the viewpoint of improving wet performance, the CTAB adsorption specific surface area of silica is preferably 90 to 260 m ² /g, more preferably 130 to 230 m ² /g.
The CTAB adsorption specific surface area is the value obtained by measuring the adsorption amount of n-hexadecyltrimethylammonium bromide on the silica surface in accordance with JIS K6217-3:2001 "Part 3: How to determine specific surface area - CTAB adsorption method" is

(Recycled Carbon Black)
The recycled carbon black (hereinafter sometimes referred to as recycled CB) used in the present invention must have a difference (ΔDBP) between DBP absorption and compressed DBP absorption (24M4DBP) of less than 20 ml/100 g, and must have a ratio of the nitrogen adsorption specific surface area _N2SA (unit: ^m2 /g) to the iodine adsorption amount IA (unit: mg/g), _N2SA /IA, in the range of 0.8 to less than 2.0. If the ΔDBP and _N2SA /IA are outside the above ranges, the effects of the present invention cannot be achieved.

From the viewpoint of further enhancing the effects of the present invention, the ΔDBP is preferably 19 ml/100 g or less, and more preferably 18 ml/100 g or less.
From the viewpoint of further enhancing the effects of the present invention, the N ₂ SA/IA is preferably from 0.8 to 1.9, and more preferably from 0.8 to 1.7.

In the present invention, DBP oil absorption is measured in accordance with ASTM D2414, compressed DBP (24M4DBP) is measured as 24M4-DBP oil absorption based on JIS K6217-4 (compressed sample), _N2SA is measured in accordance with JIS K6217-2, and IA is measured in accordance with JIS K6217-1.

The compressed DBP oil absorption amount is measured by breaking the aggregation of recycled carbon black, and by measuring the difference from the DBP oil absorption amount that maintains the aggregation, it is possible to understand how easily the structure collapses. .
It is considered that the smaller the ΔDBP, the less the structure collapses, that is, the reinforcing performance as carbon black does not deteriorate.
Furthermore, in the case of recycled carbon black, it is presumed that the plurality of types of carbon black that are blended at the time of manufacturing the tire, which is its raw material, are not destroyed by thermal decomposition and maintain their distribution. Therefore, by adjusting N ₂ SA/IA to an optimum range, even recycled carbon black can exhibit necessary and sufficient reinforcing properties.
The nitrogen adsorption specific surface area N ₂ SA of the recycled carbon black is preferably 65 to 105 m ² /g. The preferred DBP oil absorption is 70 to 105 ml/100 g.

The recycled carbon black used in the present invention can be, for example, the following recycled carbon black.
(1) Regenerated carbon black derived from natural resources. Examples of natural resources include by-products generated during the manufacturing process of various products, which can be considered as renewable raw materials. Examples of the by-products include, but are not limited to, animal and vegetable oils. The animal and vegetable oils refer to animal oils or vegetable oils, and examples of the animal oils include aquatic animal oils such as fish oil, fatty oils (liver oils) obtained from fish livers such as cod and shark, marine animal oils that can be extracted from whales, and land animal oils such as beef tallow and lard. The vegetable oils include oils and fats containing fatty acid glycerides extracted from the seeds, fruits, kernels, etc. of plants, and may be any of drying oils, semi-drying oils, non-drying oils, etc.
Regenerated carbon black derived from natural resources is commercially available, for example, Ecorax Nature 200 (trade name) manufactured by Orion Engineered Carbons SA.
(2) Regenerated carbon black produced by thermally decomposing waste tires and using the resulting pyrolysis oil as a raw material. Such recycled carbon black can be commercially available.
(3) Recycled carbon black consisting of residual carbon black produced by pyrolysis of waste tires. The pyrolysis of waste tires can be carried out according to a known method, for example, a pyrolysis method at a temperature of 300° C. or higher, more typically 600° C. or higher. Such recycled carbon black can be commercially available, for example, PB365 (trade name) manufactured by Enrestec, CONTINUA8000 (manufactured by Birla Carbon), LN607 (manufactured by Shandong Kaiyuan), etc.

As mentioned above, impurities are present in recycled carbon black. An example of an impurity is ash, and for example, the recycled carbon black of (1) and (2) above specifically contains ash of 0.5% by mass or less, more specifically 0.4% by mass or less. I'm here.
Further, the recycled carbon black (3) above contains ash, specifically 1 to 30% by mass, more specifically 3 to 25% by mass.
Even when recycled carbon black containing ash is used in this way, the present invention uses recycled carbon black that satisfies the specific range of ΔDBP and N ₂ SA/IA, so the deterioration in heat generation and wet performance can be significantly reduced. Can be suppressed.
Note that the ash content is measured by the known ICP method.

(Rubber composition blending ratio)
The rubber composition of the present invention contains the diene rubber, silica and the recycled carbon black, and is characterized in that 40 to 150 parts by mass of the silica and 1 to 10 parts by mass of the recycled carbon black are blended with respect to 100 parts by mass of the diene rubber.
If the amount of silica blended is less than 40 parts by mass, wet performance will deteriorate, whereas if it exceeds 150 parts by mass, heat build-up will deteriorate.
If the amount of the recycled carbon black is less than 1 part by mass, the amount is too small to achieve the effects of the present invention, whereas if it exceeds 10 parts by mass, wet performance deteriorates.

Further, from the viewpoint of improving the effects of the present invention, it is preferable that the following compounding conditions are satisfied.
(i) The blending amount of the silica is preferably 50 to 130 parts by mass based on 100 parts by mass of the diene rubber.
(ii) The content of the recycled carbon black is preferably 3 to 8 parts by mass per 100 parts by mass of the diene rubber.

(Other ingredients)
In addition to the above-mentioned components, the rubber composition of the present invention includes a vulcanization or crosslinking agent; a vulcanization or crosslinking accelerator; carbon black (excluding the recycled carbon black); a silane coupling agent; an anti-aging agent; Various additives commonly included in rubber compositions such as agent; resin; curing agent can be blended, and such additives are kneaded by a common method to form a composition, and then vulcanized or crosslinked. It can be used for. The blending amounts of these additives can also be set to conventional and general blending amounts as long as they do not contradict the purpose of the present invention.

(Silane coupling agent)
The rubber composition of the present invention is preferably compounded with a silane coupling agent. The silane coupling agent may be any agent that can be used in a rubber composition containing silica, and examples of such agents include bis-(3-triethoxysilylpropyl)tetrasulfide, bis(3-triethoxysilylpropyl)disulfide, 3-trimethoxysilylpropylbenzothiazoletetrasulfide, γ-mercaptopropyltriethoxysilane, and 3-octanoylthiopropyltriethoxysilane.
The amount of the silane coupling agent to be added is preferably, for example, 5 to 15% by mass relative to the silica.

(alkylalkoxysilane)
In the present invention, from the viewpoint of further improving wet performance, an alkyl alkoxysilane represented by the following formula (1) can be used.

(In formula (1), R1 represents an alkyl group having 3 to 20 carbon atoms, and Et represents an ethyl group.)
Here, as the alkyl group having 3 to 20 carbon atoms for R1, an alkyl group having 7 to 20 carbon atoms is preferable, and specific examples thereof include a heptyl group, an octyl group, a nonyl group, a decyl group, an undecyl group, a dodecyl group, etc. Among these, from the viewpoint of compatibility with diene rubber, an alkyl group having 8 to 10 carbon atoms is more preferable, and an octyl group or a nonyl group is particularly preferable.
The alkylalkoxysilane may be a commercially available product, for example, n-octyltriethoxysilane KBE-3083 manufactured by Shin-Etsu Chemical Co., Ltd.
The amount of alkylalkoxysilane blended is preferably 3 to 20% by mass, and more preferably 5 to 15% by mass, based on the silica.

(Carbon black)
In the embodiment of the present invention in which carbon black (hereinafter sometimes referred to as CB) is used, the carbon black is not particularly limited, but it is preferable that the nitrogen adsorption specific surface area N ₂ SA is 50 to 170 m ² /g and the DBP oil absorption is 60 to 140 ml/100 g.
When the N ₂ SA and DBP oil absorption of the carbon black are within the above ranges, the effects of the present invention are further improved.
When carbon black is compounded, the compounding amount is preferably 1 to 50 parts by mass, and more preferably 5 to 20 parts by mass, per 100 parts by mass of the diene rubber.
When carbon black is compounded, the total amount of the carbon black and the recycled carbon black is preferably 5 to 30 parts by mass per 100 parts by mass of the diene rubber.

Furthermore, from the viewpoint of improving the effects of the present invention, the rubber composition of the present invention preferably contains a hydrocarbon resin having a softening point of 100 to 160°C. Specific examples of the hydrocarbon resin include aromatic modified terpene resins, and examples of the aromatic modified terpene resins include terpene resins such as α-pinene, β-pinene, dipentene, and limonene, and styrene, α- Aromatically modified terpene resins obtained by polymerizing aromatic compounds such as methylstyrene, vinyltoluene, and indene are effectively used. Commercially available aromatic modified terpene resins can be used, such as YS Resin TO-125 (terpene styrene resin, Mw=2000, softening point 120 to 130° C.) manufactured by Yasuhara Chemical Co., Ltd.
The blending amount of the hydrocarbon resin is preferably 1 to 60 parts by weight, more preferably 5 to 40 parts by weight, per 100 parts by weight of the diene rubber.

(Production method)
The production method of the present invention includes a step of mixing diene rubber containing SBR, silica, recycled carbon black, and vulcanization components, and is characterized by the order of mixing these components and the mixer temperature during mixing.
That is, there is a first step in which the recycled carbon black is introduced and kneaded at a temperature below 100°C, a kneading step (second step) is performed multiple times as necessary after the first step, and finally a vulcanization system is added. It has a final step of adding the ingredients and further kneading.
In the first step, the components to be added together with the recycled carbon black are not particularly limited, except for vulcanization components. For example, the diene rubber, the carbon black, the recycled carbon black, and various components added as necessary can be added at the same time. Note that various components added as necessary refer to various additives that are generally blended into rubber compositions, such as various resins, zinc oxide, various oils, anti-aging agents, and plasticizers.
In addition, one or more components selected from the diene rubber, the carbon black, and various components added as necessary may be added and kneaded in the subsequent second step, but at least the recycled carbon black It is preferable that the carbon black and the silica are added at the same time in the first step.
After the first step is completed, vulcanization components are added to the resulting mixture in the final step, and the mixture is further kneaded . The vulcanization system components include a vulcanizing agent, a crosslinking agent, a vulcanization accelerator, and a crosslinking accelerator.

In the first step, the temperature at which the recycled carbon black is added is less than 100°C, preferably 50 to 90°C, in order to increase the dispersibility of the recycled carbon black. In the first step, the recycled carbon black may be added together with the other components, or the other components may be mixed first for, for example, 60 seconds or less, and then the recycled carbon black may be added. The mixing time after the recycled carbon black is added is, for example, 1.5 to 5 minutes. The temperature reached by the mixer in the first step is preferably 140 to 180°C. The mixing temperature in the mixer can be controlled by known temperature control means, such as a thermocouple installed in the mixer.
In the final step, the kneading temperature in the mixer is preferably, for example, 80 to 120° C. The kneading time is, for example, 0.5 to 3 minutes.
The mixers used in the first, second and final steps may be known Banbury mixers, rolls and the like that are generally used for rubber compositions. The mixture may be discharged once outside the mixer between steps and cooled, or the mixture may be cooled in the mixer at time intervals between steps. The mixers used in the first, second and final steps may be the same or different.

The rubber composition of the present invention can maintain sufficient heat generation and wet performance for practical use even when blended with recycled carbon black, and therefore can be suitably used for tire treads, particularly cap treads. The tire can also be an all-season tire or a studless tire. The tire of the present invention is preferably a pneumatic tire, and can be filled with air, an inert gas such as nitrogen, or other gases.

EXAMPLES The present invention will be further explained below with reference to Examples and Comparative Examples, but the present invention is not limited to the following Examples.

Standard Examples 1-2, Examples 1-20 and Comparative Examples 1-9
Preparation of sample In the formulation (parts by mass) shown in Table 1, the components except the vulcanization system (vulcanization accelerator, sulfur) were kneaded in a 1.7 liter closed Banbury mixer at 90°C or 130°C for 5 minutes. The mixture was then discharged outside the mixer and cooled to room temperature. Subsequently, the composition was put into the same Banbury mixer again, and a vulcanization system was added and kneaded to obtain a rubber composition. Next, the obtained rubber composition was press-vulcanized in a predetermined mold at 150° C. for 30 minutes to prepare a vulcanized rubber test piece. The physical properties of the obtained vulcanized rubber test piece were measured using the test method shown below.

Exothermic property: According to JIS K6394:2007, tan δ (60°C) was measured using a viscoelastic spectrometer (manufactured by Toyo Seiki Seisakusho) under the conditions of an extensional deformation strain rate of 10 ± 2%, a frequency of 20Hz, and a temperature of 60°C. It was measured. The results were expressed as an index with the value of Standard Example 1 or 2 set as 100. The larger the index, the lower the heat generation.
Wet performance: According to JIS K6394:2007, using a viscoelastic spectrometer (manufactured by Toyo Seiki Seisakusho), tan δ (0 °C) was measured under the conditions of an extensional strain rate of 10 ± 2%, a frequency of 20 Hz, and a temperature of 0 °C. It was measured. The results were expressed as an index with the value of Standard Example 1 or 2 set as 100. The larger the index, the better the wet performance.

Comparative examples 1 to 5 and examples 1 to 11 are compared with standard example 1, and comparative examples 6 to 9 and examples 12 to 20 are compared with standard example 2.

The results are shown in Tables 1 and 2.

*1: SBR (NS616 manufactured by ZS Elastomers Co., Ltd.)
*2: BR (Nipol BR1220 manufactured by ZS Elastomers Co., Ltd.)
*3: NR (PT.KIRANA SAPTA SIR20)
*4: Silica 1 (ZEOSIL1165MP manufactured by Solvay, CTAB specific surface area = 160 ^m2 /g)
*5: Silica 2 (Ultrasil 9000GR manufactured by Evonik, CTAB specific surface area = 200 ^m2 /g)
*6: HAF carbon black (Seat 3 manufactured by Tokai Carbon Co., Ltd., nitrogen adsorption specific surface area ( _N2SA ) = 79 ^m2 /g, DBP oil absorption = 101 ml/100 g)
*7: Recycled carbon black (product name PB365, manufactured by Enrestec, DBP oil absorption = 88 ml/100 g, compressed DBP oil absorption (24M4DBP) = 77 ml/100 g, ΔDBP = 11 ml/100 g, N ₂ SA = 76 m ² /g, IA = 95 mg/g, N ₂ SA/IA = 0.8)
*8: Recycled carbon black (manufacturer's sample, DBP oil absorption = 98 ml/100 g, compressed DBP oil absorption (24M4DBP) = 96 ml/100 g, ΔDBP = 2 ml/100 g, N ₂ SA = 102 m ² /g, IA = 86 mg/g, N ₂ SA/IA = 1.2)
*9: Recycled carbon black (product name: ECORAX NATURE 200, manufactured by OEC Corporation, DBP oil absorption = 72 ml/100 g, compressed DBP oil absorption (24M4DBP) = 69 ml/100 g, ΔDBP = 3 ml/100 g, N ₂ SA = 82 m ² /g, IA = 86 mg/g, N ₂ SA/IA = 1.0)
*10: Recycled carbon black (product name GCB774G, manufactured by LDC, DBP oil absorption = 97 ml/100 g, compressed DBP oil absorption (24M4DBP) = 77 ml/100 g, ΔDBP = 22 ml/100 g, N ₂ SA = 70 m ² /g, IA = 109 mg/g, N ₂ SA/IA = 0.6)
*11: Processing aid (Struktol HT207)
*12: Alkylalkoxysilane (KBE-3083 manufactured by Shin-Etsu Chemical Co., Ltd.)
*13: Silane coupling agent (Si69 manufactured by Evonik)
* 14: Stearic acid (beads stearic acid YR manufactured by NOF Corporation)
*15: Zinc oxide (three types of zinc oxide manufactured by Seido Chemical Industry Co., Ltd.)
*16: Anti-aging agent (EASTMAN 6PPD)
* 17: Oil (Extract No. 4 S manufactured by Showa Shell Sekiyu K.K.)
* 18: Hydrocarbon resin (Yasuhara Chemical Co., Ltd. YS Resin TO-125)
*19: Sulfur (Mu-Clon OT-20 manufactured by Shikoku Chemical Industry Co., Ltd.)
*20: Vulcanization accelerator CZ (Sansera CM-G manufactured by Sanshin Chemical Industry Co., Ltd.)
*21: Vulcanization accelerator DPZ (Sokseal D-G manufactured by Sumitomo Chemical Co., Ltd.)

From the results in Tables 1 and 2, the rubber compositions of each example contained diene rubber containing SBR, silica, and recycled carbon black, and the DBP oil absorption and compressed DBP oil absorption of the recycled carbon black (24M4DBP) (ΔDBP) is less than 20 ml/100 g, and N ₂ SA is the ratio of the nitrogen adsorption specific surface area N ₂ SA (unit: m ² /g) to the iodine adsorption amount IA (unit: mg/g) of the recycled carbon black. /IA is in the range of 0.8 or more and less than 2.0, the proportion of the styrene-butadiene copolymer rubber is 30 parts by mass or more in 100 parts by mass of the diene rubber, and 100 parts by mass of the diene rubber However, since the rubber composition is characterized by containing 40 to 150 parts by mass of silica and 1 to 10 parts by mass of the recycled carbon black, it has practically sufficient heat generation properties compared to the rubber compositions of Standard Examples 1 and 2. It can be seen that wet performance can be maintained.

On the other hand, in Comparative Example 1, the ΔDBP of the recycled carbon black exceeded the upper limit defined by the present invention, and the N ₂ SA/IA was less than the lower limit defined by the present invention, so the wet performance deteriorated.
In Comparative Example 2, the amount of recycled carbon black exceeded the upper limit specified in the present invention, so the wet performance deteriorated.
In Comparative Example 3, the amount of silica blended was less than the lower limit specified by the present invention, so the wet performance deteriorated.
In Comparative Example 4, the amount of silica exceeded the upper limit defined by the present invention, so the heat generation property and wet performance deteriorated.
In Comparative Example 5, the wet performance deteriorated because the proportion of SBR in 100 parts by mass of the diene rubber was less than the lower limit defined by the present invention.
In Comparative Example 6, the wet performance deteriorated because the ΔDBP of the recycled carbon black exceeded the upper limit defined by the present invention and the N ₂ SA/IA was less than the lower limit defined by the present invention.
In Comparative Example 7, the amount of recycled carbon black exceeded the upper limit specified in the present invention, so the heat generation property and wet performance deteriorated.
In Comparative Example 8, the amount of silica blended was less than the lower limit defined by the present invention, so the wet performance deteriorated.
In Comparative Example 9, the amount of silica blended exceeded the upper limit specified by the present invention, so the heat generation property and wet performance deteriorated.

The present invention includes the following embodiments.
Embodiment 1:
A rubber composition for tires containing a diene rubber including a styrene-butadiene copolymer rubber, silica, and recycled carbon black,
the difference (ΔDBP) between the DBP oil absorption and the compressed DBP oil absorption (24M4DBP) of the recycled carbon black is less than 20 ml/100 g;
the ratio of the nitrogen adsorption specific surface area _N2SA (unit: ^m2 /g) to the iodine adsorption amount IA (unit: mg/g) of the regenerated carbon black, _N2SA /IA, is in the range of 0.8 or more and less than 2.0;
The proportion of the styrene-butadiene copolymer rubber in 100 parts by mass of the diene rubber is 30 parts by mass or more,
A rubber composition for tires, comprising 100 parts by mass of the diene rubber, 40 to 150 parts by mass of silica, and 1 to 10 parts by mass of the recycled carbon black.
Embodiment 2:
The rubber composition for tires according to embodiment 1, characterized in that a silane coupling agent is blended in an amount of 5 to 15 mass % relative to the silica.
Embodiment 3:
3. The rubber composition for tires according to embodiment 1 or 2, wherein the silica has a CTAB specific surface area of 90 to 260 m ² /g.
Embodiment 4:
4. The rubber composition for tires according to any one of embodiments 1 to 3, wherein the styrene-butadiene copolymer rubber has a functional group capable of interacting with the silica.
Embodiment 5:
5. The rubber composition for tires according to any one of embodiments 1 to 4, further comprising 1 to 60 parts by mass of a hydrocarbon resin having a softening point of 100 to 160° C., based on 100 parts by mass of the diene rubber.
Embodiment 6:
A method for producing a rubber composition for tires, comprising a step of mixing a diene rubber including a styrene-butadiene copolymer rubber, silica, recycled carbon black, and a vulcanization component, comprising:
A first step of adding and kneading the recycled carbon black at a temperature of less than 100°C;
A final step of adding vulcanization components and further kneading the mixture after the first step,
the difference (ΔDBP) between the DBP oil absorption and the compressed DBP oil absorption (24M4DBP) of the recycled carbon black is less than 20 ml/100 g;
the ratio of the nitrogen adsorption specific surface area _N2SA (unit: ^m2 /g) to the iodine adsorption amount IA (unit: mg/g) of the recycled carbon black, _N2SA /IA, is in the range of 0.8 or more and less than 2.0; and the proportion of the styrene-butadiene copolymer rubber in 100 parts by mass of the diene rubber is 30 parts by mass or more;
A method for producing a rubber composition for tires, comprising blending 40 to 150 parts by mass of silica and 1 to 10 parts by mass of the recycled carbon black with respect to 100 parts by mass of the diene rubber.
Embodiment 7:
A tire using the rubber composition for tires according to any one of embodiments 1 to 5.
Embodiment 8:
A tire using the rubber composition for tires according to any one of embodiments 1 to 5 in the tread.

Claims (8)

A tire rubber composition containing a diene rubber including a styrene-butadiene copolymer rubber, silica, and recycled carbon black,
The difference (ΔDBP) between the DBP oil absorption amount and the compressed DBP oil absorption amount (24M4DBP) of the recycled carbon black is less than 20ml/100g,
The ratio of nitrogen adsorption specific surface area N ₂ SA (unit: m ² /g) to iodine adsorption amount IA (unit: mg/g) of the recycled carbon black, N ₂ SA/IA, is in the range of 0.8 or more and less than 2.0. Located in
The proportion of the styrene-butadiene copolymer rubber in 100 parts by mass of the diene rubber is 30 parts by mass or more,
A rubber composition for a tire, characterized in that 40 to 150 parts by mass of silica and 1 to 10 parts by mass of the recycled carbon black are blended with 100 parts by mass of the diene rubber. The rubber composition for tires according to claim 1, characterized in that a silane coupling agent is blended in a proportion of 5 to 15% by mass with respect to the silica. The rubber composition for tires according to claim 1, wherein the silica has a CTAB specific surface area of 90 to 260 m ² /g. The tire rubber composition according to claim 1, wherein the styrene-butadiene copolymer rubber has a functional group that can interact with the silica. The rubber composition for tires according to claim 1, characterized in that 1 to 60 parts by mass of a hydrocarbon resin having a softening point of 100 to 160°C is further blended with respect to 100 parts by mass of the diene rubber. A method for producing a tire rubber composition comprising a step of mixing a diene rubber containing a styrene-butadiene copolymer rubber, silica, recycled carbon black, and a vulcanization component,
A first step of adding and kneading the recycled carbon black at a temperature below 100°C;
After the first step, a final step of adding vulcanization components and further kneading,
The difference (ΔDBP) between the DBP oil absorption amount and the compressed DBP oil absorption amount (24M4DBP) of the recycled carbon black is less than 20ml/100g,
The ratio of nitrogen adsorption specific surface area N ₂ SA (unit: m ² /g) to iodine adsorption amount IA (unit: mg/g) of the recycled carbon black, N ₂ SA/IA, is in the range of 0.8 or more and less than 2.0. Located in
The proportion of the styrene-butadiene copolymer rubber in 100 parts by mass of the diene rubber is 30 parts by mass or more,
A method for producing a rubber composition for a tire, comprising blending 40 to 150 parts by mass of silica and 1 to 10 parts by mass of the recycled carbon black to 100 parts by mass of the diene rubber. A tire using the tire rubber composition according to claim 1. A tire using the tire rubber composition according to claim 1 in the tread.