WO2023008105A1 - タイヤトレッド用ゴム組成物、及びタイヤ - Google Patents
タイヤトレッド用ゴム組成物、及びタイヤ Download PDFInfo
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- WO2023008105A1 WO2023008105A1 PCT/JP2022/026637 JP2022026637W WO2023008105A1 WO 2023008105 A1 WO2023008105 A1 WO 2023008105A1 JP 2022026637 W JP2022026637 W JP 2022026637W WO 2023008105 A1 WO2023008105 A1 WO 2023008105A1
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- rubber
- mass
- carbon black
- rubber composition
- butadiene rubber
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B60—VEHICLES IN GENERAL
- B60C—VEHICLE TYRES; TYRE INFLATION; TYRE CHANGING; CONNECTING VALVES TO INFLATABLE ELASTIC BODIES IN GENERAL; DEVICES OR ARRANGEMENTS RELATED TO TYRES
- B60C1/00—Tyres characterised by the chemical composition or the physical arrangement or mixture of the composition
- B60C1/0016—Compositions of the tread
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- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
- C08K3/00—Use of inorganic substances as compounding ingredients
- C08K3/02—Elements
- C08K3/04—Carbon
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
- C08L7/00—Compositions of natural rubber
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
- C08L9/00—Compositions of homopolymers or copolymers of conjugated diene hydrocarbons
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
- C08K2201/00—Specific properties of additives
- C08K2201/002—Physical properties
- C08K2201/006—Additives being defined by their surface area
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
- Y02T10/00—Road transport of goods or passengers
- Y02T10/80—Technologies aiming to reduce greenhouse gasses emissions common to all road transportation technologies
- Y02T10/86—Optimisation of rolling resistance, e.g. weight reduction
Definitions
- the present invention relates to tire tread rubber compositions and tires.
- Tire treads are particularly required to have wear resistance, and performance is being improved by optimizing the materials used to make the treads.
- Patent Document 1 describes a rubber composition obtained by combining a relatively high cis-content butadiene-based polymer modified with a predetermined modifier and carbon black having a nitrogen adsorption specific surface area of more than 100 m 2 /g. It is disclosed that a pneumatic tire having both excellent low rolling resistance and wear resistance can be obtained by using it.
- Patent Document 1 has room for improvement in terms of further improving wear resistance.
- an object of the present invention is to provide a rubber composition for a tire tread, which is capable of exhibiting excellent wear resistance in a tire when used in the tread.
- Another object of the present invention is to provide a tire having excellent wear resistance.
- the inventors of the present invention have found that by using carbon black having predetermined physical properties and using both modified butadiene rubber and unmodified butadiene rubber in predetermined amounts as rubber components, abrasion resistance is achieved.
- the inventors have found that a rubber composition capable of improving the properties can be obtained, and have completed the present invention.
- the gist and configuration of the present invention for solving the above problems is as follows.
- the tire tread rubber composition of the present invention is Contains a rubber component and carbon black,
- the rubber component has a modified butadiene rubber ratio of 5% by mass or more and an unmodified butadiene rubber ratio of 10% by mass or more
- the carbon black has a cetyltrimethylammonium bromide adsorption specific surface area (CTAB) of 130 m 2 /g or more, and a ratio (CTAB/IA) of the CTAB (m 2 /g) to the iodine adsorption amount (IA) (mg/g) 0.92 or more and 1.06 or less, and a hydrogen release amount of 3500 mass ppm or more and 4800 mass ppm or less, It is characterized by
- the tire of the present invention is characterized by using the tire tread rubber composition described above in the tread.
- the rubber composition for tire treads which can express the wear resistance which was excellent in the tire by using for a tread can be provided. Moreover, according to the present invention, it is possible to provide a tire having excellent wear resistance.
- the compounds described herein may be partially or wholly derived from fossil resources, may be derived from biological resources such as plant resources, or may be derived from recycled resources such as used tires. may be It may also be derived from a mixture of any two or more of fossil resources, biological resources, and recycled resources.
- Rubber composition for tire tread A rubber composition for a tire tread according to one embodiment of the present invention (hereinafter sometimes referred to as "rubber composition of the present embodiment") contains a rubber component and carbon black.
- the rubber component should have a modified butadiene rubber content of 5% by mass or more and an unmodified butadiene rubber content of 10% by mass or more.
- the carbon black used in the present embodiment has a cetyltrimethylammonium bromide adsorption specific surface area (CTAB) of 130 m 2 /g or more as a first physical property, and an iodine adsorption amount (IA) (
- CTAB/IA) of the CTAB (m 2 /g) to mg/g) is 0.92 or more and 1.06 or less
- the hydrogen release amount is 3500 mass ppm or more and 4800 mass Must be ppm or less.
- a carbon black having such properties at the same time is substantially new.
- the rubber composition of the present embodiment includes modified butadiene rubber (also referred to as modified BR) and unmodified butadiene rubber (also referred to as unmodified BR or simply BR) as essential rubber components. .) and Surprisingly, in the present embodiment, a rubber composition obtained by using carbon black having predetermined physical properties described later and a modified butadiene rubber and an unmodified butadiene rubber as rubber components in predetermined amounts is It was found that excellent wear resistance can be expressed. In this regard, the modified butadiene rubber, by chemically bonding with carbon black, exhibits excellent reinforcing properties and improves abrasion resistance, but can deteriorate filler dispersibility on the order of micrometers.
- modified butadiene rubber by chemically bonding with carbon black, exhibits excellent reinforcing properties and improves abrasion resistance, but can deteriorate filler dispersibility on the order of micrometers.
- a modified butadiene rubber is a butadiene rubber having one or more functional groups having atoms other than carbon and hydrogen.
- the modified butadiene rubber may have the above functional group at the terminal or in the main chain.
- Modified butadiene rubber can be obtained, for example, by modifying butadiene rubber (unmodified butadiene rubber) with a modifier.
- Atoms other than carbon and hydrogen include a nitrogen atom, an oxygen atom, a sulfur atom, a metalloid atom, a metal atom, and the like, and the functional group preferably has one or more atoms selected from these.
- the metalloid atoms include boron, silicon, germanium, arsenic, antimony, tellurium and the like. Among these, one or more atoms selected from boron, silicon and germanium are more preferable, and silicon is particularly preferable.
- the 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.
- the proportion of the modified butadiene rubber in the rubber component is 5% by mass or more. If the ratio of the modified butadiene rubber in the rubber component is less than 5% by mass, the effect of combined use with the unmodified butadiene rubber, and thus the effect of improving wear resistance, cannot be sufficiently obtained. Moreover, the proportion of the modified butadiene rubber in the rubber component is preferably 15% by mass or more, more preferably 20% by mass or more, from the viewpoint of further improving wear resistance. On the other hand, the upper limit of the ratio of the modified butadiene rubber in the rubber component is not particularly limited. The following are preferable.
- non-modified butadiene rubber is used in addition to the above-described modified butadiene rubber.
- the unmodified butadiene rubber may be used singly or in combination of two or more.
- the proportion of unmodified butadiene rubber in the rubber component is 10% by mass or more. If the proportion of unmodified butadiene rubber in the rubber component is less than 10% by mass, the effect of combined use with modified butadiene rubber, and thus the effect of improving abrasion resistance, cannot be sufficiently obtained.
- the upper limit of the proportion of the unmodified butadiene rubber is not particularly limited, it is preferably 30% by mass or less, more preferably 20% by mass or less, from the viewpoint of further improving wear resistance.
- the ratio of the modified butadiene rubber to the total of the modified butadiene rubber and the unmodified butadiene rubber is preferably 20% by mass or more and 80% by mass or less. In this case, the effect of improving wear resistance unique to the present invention can be obtained more sufficiently.
- the ratio of the modified butadiene rubber in the total of the modified butadiene rubber and the unmodified butadiene rubber is preferably 45% by mass or more, more preferably 60% by mass or more, and 70% by mass or more. It is even more preferable to have
- the rubber composition of the present embodiment preferably further contains natural rubber (NR) in addition to the modified butadiene rubber and unmodified butadiene rubber described above.
- the rubber component used in the present embodiment preferably further contains natural rubber. In this case, the mechanical strength of the rubber article can be enhanced.
- 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, when the ratio of natural rubber in the rubber component is 70% by mass or less, the combined use of the modified butadiene rubber and the unmodified butadiene rubber is sufficiently effective, and the wear resistance improvement effect peculiar to the present invention is exhibited. can be obtained more reliably.
- the rubber composition of the present embodiment may or may not contain rubber components other than the above-described modified butadiene rubber, unmodified butadiene rubber, and natural rubber.
- Other rubber components include, for example, isoprene rubber (IR), styrene-butadiene rubber (SBR), acrylonitrile-butadiene rubber (NBR), chloroprene rubber, ethylene-propylene rubber (EPM), ethylene-propylene-diene rubber (EPDM). , polysulfide rubber, silicone rubber, fluororubber, urethane rubber, and the like.
- Other rubber components may be used singly or in combination of two or more.
- the ratio of the other rubber components in the rubber component is preferably 20% by mass or less, more preferably 10% by mass or less, and 5% by mass or less. More preferably, it is 0% by mass (that is, contains no other rubber components), particularly preferably.
- Carbon black used in the present embodiment is required to have a cetyltrimethylammonium bromide adsorption specific surface area (CTAB) of 130 m 2 /g or more as a first physical property. Since the carbon black has a CTAB of 130 m 2 /g or more, it can enhance the reinforcing properties of the modified butadiene rubber and/or the unmodified butadiene rubber mixed as a rubber component, and can contribute to the improvement of wear resistance. . Further, the CTAB of the carbon black is preferably 135 m 2 /g or more from the viewpoint of further improving wear resistance, and from the viewpoint of maintaining good other performance such as low loss property and workability. , 150 m 2 /g or less.
- CTAB cetyltrimethylammonium bromide adsorption specific surface area
- the CTAB of carbon black is measured according to JIS K6217-3.
- the adjustment of CTAB of carbon black is not limited, but for example, it is performed by controlling various conditions such as raw material introduction conditions, air introduction conditions, fuel introduction conditions, cooling water introduction conditions, etc. when producing carbon black. be able to.
- 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, the surface of the carbon black is appropriately activated in a predetermined manner, and the interaction with the modified butadiene rubber and/or unmodified butadiene rubber mixed as a rubber component is improved. It can be improved well.
- the IA of the carbon black is preferably 130 mg/g or more from the viewpoint of favorably maintaining other performances such as low loss property and workability.
- the IA of carbon black is measured according to JIS K6217-1.
- the adjustment of the IA of carbon black is not limited, but for example, by controlling various conditions such as raw material introduction conditions, air introduction conditions, fuel introduction conditions, and cooling water introduction conditions when producing carbon black. be able to.
- the carbon black has 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. require something. If CTAB/IA is less than 0.92, wear resistance may deteriorate. Moreover, when CTAB/IA exceeds 1.06, there is a possibility that the workability deteriorates and, in turn, the wear resistance deteriorates. Moreover, from the viewpoint of further improving wear resistance, the CTAB/IA of the carbon black is preferably 0.95 or more and preferably 1.05 or less.
- the carbon black is required to have a hydrogen release amount of 3500 mass ppm or more and 4800 mass ppm or less as a third physical property. If the hydrogen release amount is less than 3500 ppm by mass, the predetermined activation of the surface of the carbon black, and thus the interaction with the modified butadiene rubber and/or unmodified butadiene rubber mixed as a rubber component will be insufficient, resulting in There is a possibility that wear resistance will deteriorate. Moreover, if the amount of hydrogen released exceeds 4800 ppm by mass, there is a possibility that wear resistance may deteriorate due to excess hydrogen.
- the hydrogen release amount of the carbon black is preferably 3700 mass ppm or more, preferably 4500 mass ppm or less, and 4300 mass ppm or less from the viewpoint of further improving wear resistance. is more preferred.
- 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 amount of hydrogen released from carbon black is not limited, for example, various conditions such as raw material introduction conditions, air introduction conditions, fuel introduction conditions, cooling water introduction conditions, etc. when producing carbon black can be controlled. can be done with
- the 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, wear resistance is further improved, and if it is 150 cm 3 /100 g or less, workability can be maintained well.
- DBP dibutyl phthalate oil absorption
- the method for producing the above carbon black is not particularly limited as long as it can have the desired physical properties. However, it is extremely difficult to independently adjust physical properties of carbon black such as CTAB, IA and hydrogen release amount. Carbon black that can be used in the present embodiment can be produced, for example, according to the production conditions shown in Table 1 of Examples below.
- the content of the carbon black in the rubber composition of the present 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 rubber component.
- the content of the carbon black is 40 parts by mass or more, the interaction with the modified butadiene rubber and/or the unmodified butadiene rubber mixed as a rubber component is sufficiently enhanced, and the wear resistance is effectively improved. be able to.
- the content of the carbon black is 70 parts by mass or less, other performances such as low-loss property and workability can be maintained satisfactorily.
- the content of the 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 rubber component. .
- the rubber composition of the present embodiment may or may not contain carbon black other than the carbon black having the physical properties described above.
- Other carbon blacks include carbon black that satisfies only two of the above-described first physical property, second physical property, and third physical property, carbon black that satisfies only one, or carbon black that satisfies none of them. mentioned.
- the ratio of other carbon blacks in the total carbon blacks should be 20% by mass or less. It is preferably 10% by mass or less, still more preferably 5% by mass or less, and particularly preferably 0% by mass (that is, containing no other carbon black).
- the rubber composition of the present embodiment may contain fillers other than carbon black.
- fillers other than carbon black include silica, aluminum hydroxide, clay, alumina, talc, mica, kaolin, glass balloons, glass beads, calcium carbonate, magnesium carbonate, magnesium hydroxide, magnesium oxide, titanium oxide, and titanium. and potassium sulfate, barium sulfate, and the like.
- the rubber composition of the present embodiment does not contain fillers other than carbon black.
- the rubber composition of the present embodiment includes a cross-linking agent (vulcanizing agent) such as sulfur, a cross-linking accelerator (vulcanization accelerator), process oil, an anti-scorch agent, zinc white, stearic acid, etc., which are commonly used in the rubber industry.
- a cross-linking agent vulcanizing agent
- vulcanization accelerator vulcanization accelerator
- process oil an anti-scorch agent
- zinc white stearic acid
- stearic acid etc.
- the compounding agents used can be appropriately selected and contained within a range not departing from the object of the present invention. Commercially available products can be suitably used as these compounding agents.
- the rubber composition can be produced by blending the rubber component with carbon black and, if necessary, various compounding agents appropriately selected, followed by kneading, heating, extrusion, and the like.
- 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 and carbon black using a kneader such as a Banbury mixer, a roll, or an internal mixer.
- a kneader such as a Banbury mixer, a roll, or an internal mixer.
- the cross-linking accelerator and components other than the cross-linking agent are mixed in the non-producing (non-pro) stage, and the cross-linking accelerator and the cross-linking agent are blended and mixed in the mixture in the pro-producing (pro) stage to prepare the rubber composition. good too.
- the rubber composition of this embodiment can be crosslinked or vulcanized.
- the conditions for cross-linking or vulcanizing the rubber composition may be appropriately adjusted, for example, the temperature is 120 to 200° C. and the heating time is 1 to 900 minutes.
- a tire according to one embodiment of the present invention is characterized by using the rubber composition of the present embodiment for a tread. Since the tire has a tread made of the rubber composition of the present embodiment, it has excellent wear resistance.
- the method for manufacturing the tire is not particularly limited, except that the rubber composition of the present embodiment is used for the tread, and known methods can be used.
- Carbon blacks CB1 to CB8 were produced respectively.
- the physical properties of each carbon black were controlled by changing various conditions (raw material introduction amount, air introduction amount, temperature, pressure, reaction time, etc.) as shown in Table 1.
- CTAB cetyltrimethylammonium bromide adsorption specific surface area
- IA iodine adsorption amount
- HMI-BR modified butadiene rubber
- tin tetrachloride as a modifier (coupling agent) was quickly added to this polymerization reaction system, and the mixture was further stirred at 50° C. for 30 minutes for modification reaction. Thereafter, 0.5 mL of an isopropanol solution of 2,6-di-t-butyl-p-cresol (BHT) (BHT concentration: 5% by mass) is added to the polymerization reaction system to stop the reaction, and further according to a conventional method. After drying, a modified butadiene rubber (HMI-BR) having tin atoms was obtained.
- BHT 2,6-di-t-butyl-p-cresol
- the amount of vinyl bond in the butadiene portion was measured from the integration ratio of the 1 H-NMR spectrum and found to be 14%, and the glass transition temperature (Tg) was obtained from the inflection point of the DSC curve. , ⁇ 95° C., and the coupling ratio was 65% as 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).
- Carbon gel amount ⁇ (M1) - (M0) x (C1 ⁇ C0) ⁇ / ⁇ (M0) x (C2 ⁇ C0) ⁇ M0: Mass of test piece (before immersion) M1: Mass of residue C0: Total number of blended parts of rubber composition C1: Sum of blended parts of carbon black, zinc white and sulfur in rubber composition C2: Rubber in rubber composition Sum of component parts
- Example 1 The rubber compositions prepared in Example 1, Comparative Example 1, and Comparative Example 2 were used as tread members and vulcanized appropriately to produce pneumatic tires for trucks and buses of size 275/80R22.5.
- the resulting tire was mounted on a driving wheel of a truck and run on a public road for 14,000 km or more, and then the amount of wear was measured from the change in the depth of the main groove of the tire.
- predictions were made based on the measurement results of Example 1, Comparative Examples 1 and 2, and the wear resistance evaluation results of each example by laboratory tests. Then, the reciprocal of the amount of wear in Comparative Example 6 was set to 100, and the wear resistance in each example was evaluated as an index.
- Table 3 shows the results. It shows that it is excellent in wear resistance, so that an index value is large.
- Modified BR Prepared modified butadiene rubber (HMI-BR) *3 Undenatured BR: “UBEPOL BR150L” manufactured by Ube Industries, Ltd. * 4 Vulcanization accelerator CZ: N-cyclohexyl-2-benzothiazylsulfenamide, manufactured by Ouchi Shinko Kagaku Kogyo Co., Ltd., "Noccellar CZ" *5 Predicted value based on wear resistance evaluation results from laboratory tests
- the rubber composition for tire treads which can express the wear resistance which was excellent in the tire by using for a tread can be provided. Moreover, according to the present invention, it is possible to provide a tire having excellent wear resistance.
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Abstract
Description
また、本発明は、耐摩耗性に優れたタイヤを提供することを課題とする。
ゴム成分及びカーボンブラックを含有し、
前記ゴム成分は、変性ブタジエンゴムの割合が5質量%以上、且つ、無変性ブタジエンゴムの割合が10質量%以上であり、
前記カーボンブラックは、セチルトリメチルアンモニウムブロマイド吸着比表面積(CTAB)が130m2/g以上、ヨウ素吸着量(IA)(mg/g)に対する前記CTAB(m2/g)の比(CTAB/IA)が0.92以上1.06以下、且つ、水素放出量が3500質量ppm以上4800質量ppm以下である、
ことを特徴とする。
また、本発明によれば、耐摩耗性に優れたタイヤを提供することができる。
また、本明細書に記載されている化合物は、部分的に、又は全てが化石資源由来であってもよく、植物資源等の生物資源由来であってもよく、使用済タイヤ等の再生資源由来であってもよい。また、化石資源、生物資源、再生資源のいずれか2つ以上の混合物由来であってもよい。
本発明の一実施形態に係るタイヤトレッド用ゴム組成物(以下、「本実施形態のゴム組成物」と称することがある。)は、ゴム成分及びカーボンブラックを含有する。上記ゴム成分は、変性ブタジエンゴムの割合が5質量%以上、且つ、無変性ブタジエンゴムの割合が10質量%以上であることを要する。また、本実施形態で用いる上記カーボンブラックは、第1の物性として、セチルトリメチルアンモニウムブロマイド吸着比表面積(CTAB)が130m2/g以上であり、第2の物性として、ヨウ素吸着量(IA)(mg/g)に対する前記CTAB(m2/g)の比(CTAB/IA)が0.92以上1.06以下であり、且つ、第3の物性として、水素放出量が3500質量ppm以上4800質量ppm以下であることを要する。なお、かかる物性を同時に具備するカーボンブラックは、実質的には新規である。
本実施形態のゴム組成物は、上述の通り、必須のゴム成分として、変性ブタジエンゴム(変性BRとも称される。)と、無変性ブタジエンゴム(無変性BR、又は、単にBRとも称される。)とを含有する。本実施形態においては、驚くべきことに、後述する所定の物性を有するカーボンブラックとともに、ゴム成分として変性ブタジエンゴム及び無変性ブタジエンゴムを所定の量で併用することで、得られるゴム組成物が、優れた耐摩耗性を発現できることが見出された。この点に関し、変性ブタジエンゴムは、カーボンブラックと化学的に結合することで優れた補強性を発現し、耐摩耗性を向上させる一方、マイクロメートルオーダーのフィラー分散性を悪化させ得る。このフィラー分散性の悪化は、耐摩耗性に対して不利に働き得る。そこで、無変性ブタジエンゴムを併用することにより、フィラー分散性が向上して、補強性及びフィラー分散性を高次元で両立でき、結果として優れた耐摩耗性が発現されると考えられる。そのため、変性ブタジエンゴムを用いるが無変性ブタジエンゴムを用いない場合、及び、無変性ブタジエンゴムを用いるが変性ブタジエンゴムを用いない場合のいずれにおいても、十分な耐摩耗性の向上効果を得ることができない。
本実施形態で用いるカーボンブラックは、第1の物性として、セチルトリメチルアンモニウムブロマイド吸着比表面積(CTAB)が130m2/g以上であることを要する。上記カーボンブラックは、CTABが130m2/g以上であるので、ゴム成分として混合される変性ブタジエンゴム及び/又は無変性ブタジエンゴムの補強性を高め、ひいては耐摩耗性の向上に寄与することができる。また、上記カーボンブラックのCTABは、耐摩耗性をより向上させる観点から、135m2/g以上であることが好ましく、また、低ロス性や加工性等の他の性能を良好に保持する観点から、150m2/g以下であることが好ましい。
なお、カーボンブラックのCTABは、JIS K6217-3に準拠して測定される。また、カーボンブラックのCTABの調整は、限定されないが、例えば、カーボンブラックを製造する際の、原料導入条件、空気導入条件、燃料導入条件、冷却水導入条件等の各種条件をコントロールすることで行うことができる。
なお、カーボンブラックのIAは、JIS K6217-1に準拠して測定される。また、カーボンブラックのIAの調整は、限定されないが、例えば、カーボンブラックを製造する際の、原料導入条件、空気導入条件、燃料導入条件、冷却水導入条件等の各種条件をコントロールすることで行うことができる。
なお、カーボンブラックの水素放出量は、アルゴン雰囲気中2000℃で15分間加熱したときに放出される水素ガスの量を指し、水素分析装置を用いて測定される。また、カーボンブラックの水素放出量の調整は、限定されないが、例えば、カーボンブラックを製造する際の、原料導入条件、空気導入条件、燃料導入条件、冷却水導入条件等の各種条件をコントロールすることで行うことができる。
本実施形態のゴム組成物は、カーボンブラック以外の充填剤を含有してもよい。カーボンブラック以外の充填剤としては、例えば、シリカ、水酸化アルミニウム、クレー、アルミナ、タルク、マイカ、カオリン、ガラスバルーン、ガラスビーズ、炭酸カルシウム、炭酸マグネシウム、水酸化マグネシウム、酸化マグネシウム、酸化チタン、チタン酸カリウム、硫酸バリウム等が挙げられる。但し、本発明特有の耐摩耗性の向上効果をより確実に得る観点から、本実施形態のゴム組成物は、カーボンブラック以外の充填剤を含有しないことが好ましい。
そして、前記ゴム組成物は、ゴム成分に、カーボンブラックと、必要に応じて適宜選択した各種配合剤とを配合し、混練り、熱入れ、押出等をすることにより製造することができる。
本発明の一実施形態に係るタイヤは、本実施形態のゴム組成物をトレッドに用いたことを特徴とする。上記タイヤは、トレッドが本実施形態のゴム組成物から作製されているため、耐摩耗性に優れる。
カーボンブラックCB1~CB8をそれぞれ作製した。なお、各カーボンブラックにおける物性の制御は、表1に示すように各種条件(原料導入量、空気導入量、温度、圧力、反応時間など)を変更することにより行った。
乾燥し、窒素置換した約900mLの耐圧ガラス容器に、シクロヘキサン283g、1,3-ブタジエン50g、2,2-ジテトラヒドロフリルプロパン0.0057mmol、及びヘキサメチレンイミン(HMI-BR)0.513mmolを加え、更にn-ブチルリチウム(BuLi)0.57mmolを加えた後、撹拌装置を具えた50℃の温水浴中で4.5時間重合を行った。この際の重合転化率は、ほぼ100%であった。次に、この重合反応系に、変性剤(カップリング剤)として四塩化スズ0.100mmolを速やかに加え、更に50℃で30分間撹拌して変性反応を行った。その後、重合反応系に、2,6-ジ-t-ブチル-p-クレゾール(BHT)のイソプロパノール溶液(BHT濃度:5質量%)0.5mLを加えて、反応を停止させ、更に常法に従って乾燥して、スズ原子を有する変性ブタジエンゴム(HMI-BR)を得た。得られたHMI-BRについて、1H-NMRスペクトルの積分比からブタジエン部分のビニル結合量を測定したところ、14%であり、DSC曲線の変曲点からガラス転移温度(Tg)を求めたところ、-95℃であり、ゲルパーミエーションクロマトグラフィー(GPC)による分子量分布曲線の全体の面積に対する最も高分子量側のピーク面積の割合からカップリング率を求めたところ、65%であった。
次に、表3に示す配合処方にて十分に混練して、ゴム組成物を調製した。得られたゴム組成物を用いて、下記の手順に従って耐摩耗性の評価を行った。
耐摩耗性との相関度が高いとされているカーボンゲル量及びフィラー分散性に基づき、各例の耐摩耗性(ラボ試験)を指数評価した。
各例において調製した未加硫状態のゴム組成物を小さく切って試験片とし、質量(M0)を測定した。この試験片をテトラヒドロフランに48時間浸漬した後、フィルターでろ過・乾燥し、残留物の質量(M1)を測定した。そして、下式により、各例における「カーボンゲル量」を算出した。カーボンゲル量が大きいほど、補強性に優れることを示し、耐摩耗効果が高いとされる。
カーボンゲル量={(M1)-(M0)×(C1÷C0)}/{(M0)×(C2÷C0)}
M0:試験片(浸漬前)の質量
M1:残留物の質量
C0:ゴム組成物の全配合部数
C1:ゴム組成物におけるカーボンブラック、亜鉛華及び硫黄の配合部数の和
C2:ゴム組成物におけるゴム成分の配合部数の和
また、上記とは別に、各例において調製したゴム組成物を、145℃で33分間加硫し、加硫ゴムを得た。得られた加硫ゴムに対し、ディスパグレーダー(米TECH PRO社製)を用い、RCBメソッドのY値を測定した。この値が大きいほど、フィラー分散性に優れることを示し、耐摩耗効果が高いとされる。
上記で算出したカーボンゲル量及びフィラー分散性を用い、各例における耐摩耗性(ラボ試験)を指数評価した。結果を表3に示す。補強性及びフィラー分散性がそれぞれ向上すると、良好な耐摩耗性が得られることから、指数値が大きいほど、耐摩耗性に優れることを示す。
実施例1、比較例1及び比較例2において調製したゴム組成物をトレッド部材に用い、適宜加硫を行って、サイズ275/80R22.5のトラック・バス用空気入りタイヤを作製した。得られたタイヤをトラックの駆動輪に装着し、公道を14000km以上走行させた後、タイヤの主溝深さの変化から、摩耗量を測定した。それ以外の実施例及び比較例においては、実施例1、比較例1及び比較例2の測定結果及び各例のラボ試験による耐摩耗性の評価結果に基づいて予測した。そして、比較例6の摩耗量の逆数を100として、各例における耐摩耗性を指数評価した。結果を表3に示す。指数値が大きいほど、耐摩耗性に優れることを示す。
*2 変性BR:調製した変性ブタジエンゴム(HMI-BR)
*3 無変性BR:宇部興産株式会社製、「UBEPOL BR150L」
*4 加硫促進剤CZ:N-シクロヘキシル-2-ベンゾチアジルスルフェンアミド、大内新興化学工業株式会社製、「ノクセラーCZ」
*5 ラボ試験による耐摩耗性の評価結果からの予測値
また、本発明によれば、耐摩耗性に優れたタイヤを提供することができる。
Claims (6)
- ゴム成分及びカーボンブラックを含有し、
前記ゴム成分は、変性ブタジエンゴムの割合が5質量%以上、且つ、無変性ブタジエンゴムの割合が10質量%以上であり、
前記カーボンブラックは、セチルトリメチルアンモニウムブロマイド吸着比表面積(CTAB)が130m2/g以上、ヨウ素吸着量(IA)(mg/g)に対する前記CTAB(m2/g)の比(CTAB/IA)が0.92以上1.06以下、且つ、水素放出量が3500質量ppm以上4800質量ppm以下である、
ことを特徴とする、タイヤトレッド用ゴム組成物。 - 前記ゴム成分中の前記変性ブタジエンゴムの割合が、30質量%以下である、請求項1に記載のタイヤトレッド用ゴム組成物。
- 前記カーボンブラックのCTABが、135m2/g以上150m2/g以下である、請求項1又は2に記載のタイヤトレッド用ゴム組成物。
- 前記カーボンブラックの含有量が、前記ゴム成分100質量部に対して40質量部以上70質量部以下である、請求項1~3のいずれかに記載のタイヤトレッド用ゴム組成物。
- 前記ゴム成分が、天然ゴムを更に含む、請求項1~4のいずれかに記載のタイヤトレッド用ゴム組成物。
- 請求項1~5のいずれかに記載のタイヤトレッド用ゴム組成物をトレッドに用いたことを特徴とする、タイヤ。
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| WO2010038768A1 (ja) * | 2008-10-01 | 2010-04-08 | 株式会社ブリヂストン | ゴム組成物及びそれを用いた空気入りタイヤ |
| WO2014181776A1 (ja) * | 2013-05-07 | 2014-11-13 | 株式会社ブリヂストン | ゴム組成物及びそれを用いたタイヤ |
| WO2014189102A1 (ja) * | 2013-05-24 | 2014-11-27 | 株式会社ブリヂストン | ゴム組成物 |
| JP2015000900A (ja) * | 2013-06-14 | 2015-01-05 | 住友ゴム工業株式会社 | ゴム組成物及び空気入りタイヤ |
| WO2019240226A1 (ja) * | 2018-06-13 | 2019-12-19 | 株式会社ブリヂストン | ゴム組成物、タイヤトレッド用ゴム組成物及びタイヤ |
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| JP5453049B2 (ja) * | 2009-10-26 | 2014-03-26 | 株式会社ブリヂストン | トレッド用ゴム組成物及びそれを用いたタイヤ |
| JP7110887B2 (ja) * | 2018-10-02 | 2022-08-02 | 住友ゴム工業株式会社 | 重荷重用タイヤ |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| WO2010038768A1 (ja) * | 2008-10-01 | 2010-04-08 | 株式会社ブリヂストン | ゴム組成物及びそれを用いた空気入りタイヤ |
| WO2014181776A1 (ja) * | 2013-05-07 | 2014-11-13 | 株式会社ブリヂストン | ゴム組成物及びそれを用いたタイヤ |
| WO2014189102A1 (ja) * | 2013-05-24 | 2014-11-27 | 株式会社ブリヂストン | ゴム組成物 |
| JP2015000900A (ja) * | 2013-06-14 | 2015-01-05 | 住友ゴム工業株式会社 | ゴム組成物及び空気入りタイヤ |
| WO2019240226A1 (ja) * | 2018-06-13 | 2019-12-19 | 株式会社ブリヂストン | ゴム組成物、タイヤトレッド用ゴム組成物及びタイヤ |
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| JP2023020658A (ja) | 2023-02-09 |
| US20240308272A1 (en) | 2024-09-19 |
| CN117751158A (zh) | 2024-03-22 |
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