WO2013027690A1 - 空気入りタイヤ - Google Patents
空気入りタイヤ Download PDFInfo
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- WO2013027690A1 WO2013027690A1 PCT/JP2012/070952 JP2012070952W WO2013027690A1 WO 2013027690 A1 WO2013027690 A1 WO 2013027690A1 JP 2012070952 W JP2012070952 W JP 2012070952W WO 2013027690 A1 WO2013027690 A1 WO 2013027690A1
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- mass
- rubber
- rubber composition
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- sidewall
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- 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
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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
- B60C1/0025—Compositions of the sidewalls
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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
- B60C1/0041—Compositions of the carcass layers
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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
- C08K3/06—Sulfur
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- 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
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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
- B60C9/00—Reinforcements or ply arrangement of pneumatic tyres
- B60C9/02—Carcasses
- B60C2009/0269—Physical properties or dimensions of the carcass coating 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
- B60C9/00—Reinforcements or ply arrangement of pneumatic tyres
- B60C9/02—Carcasses
- B60C2009/0269—Physical properties or dimensions of the carcass coating rubber
- B60C2009/0276—Modulus; Hardness; Loss modulus or "tangens delta"
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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
- B60C2200/00—Tyres specially adapted for particular applications
- B60C2200/06—Tyres specially adapted for particular applications for heavy duty vehicles
Definitions
- the present invention relates to a pneumatic tire.
- the pneumatic tire is composed of various members such as a sidewall and a case, in addition to the tread in contact with the road surface.
- a laboratory test was performed for each rubber composition of each member, and the best rubber composition was designed for each member (for example, Patent Documents 1 to 3). And based on the evaluation result of this laboratory test, the pneumatic tire was produced combining each member comprised with each best rubber composition.
- the durability of the produced pneumatic tire is often lower than the durability expected from the results of laboratory vulcanization / lab tests of the rubber compound alone.
- Japanese Patent No. 4308289 JP 2008-24913 A Japanese Patent No. 4246245
- An object of the present invention is to solve the above problems and to provide a pneumatic tire excellent in durability.
- the present invention is a pneumatic tire having a sidewall and a case, wherein the sidewall has a butadiene rubber content of 30 to 70% by mass in 100% by mass of the rubber component, and sulfur with respect to 100 parts by mass of the rubber component.
- the sidewall has a butadiene rubber content of 30 to 70% by mass in 100% by mass of the rubber component, and sulfur with respect to 100 parts by mass of the rubber component.
- the present invention relates to a pneumatic tire in which the sulfur content of the rubber composition and the rubber composition for covering a steel cord satisfies the following relational expression. 2.70 ⁇ (Sulfur content with respect to 100 parts by mass of rubber component of steel cord covering rubber composition) ⁇ (Sulfur content with respect to 100 parts by mass of rubber component of rubber composition for sidewall
- the sulfur content of the rubber composition for a sidewall and the rubber composition for coating a steel cord satisfies the following relational expression. 2.80 ⁇ (Sulfur content with respect to 100 parts by mass of rubber component of rubber composition for covering steel cord) ⁇ (Sulfur content with respect to 100 parts by mass of rubber component of rubber composition for sidewall) ⁇ 3.70
- the vulcanization mold temperature or the steam filling temperature of the vulcanizer is preferably 130 to 158 ° C.
- the total content of natural rubber, isoprene rubber, liquid isoprene rubber and styrene butadiene rubber in 100% by mass of the rubber component of the sidewall rubber composition is preferably 30 to 70% by mass.
- the rubber composition for sidewalls preferably contains butadiene rubber containing 1,2-syndiotactic polybutadiene crystals as butadiene rubber.
- the content of the vulcanization accelerator in the sidewall rubber composition is preferably 0.3 to 0.8 parts by mass with respect to 100 parts by mass of the rubber component.
- the pneumatic tire is preferably a heavy duty tire.
- a pneumatic tire having a sidewall and a case, wherein the sidewall is made of a rubber composition for a sidewall containing a specific amount of butadiene rubber and sulfur, and the case is coated with a steel cord.
- This is a pneumatic tire that is coated with the rubber composition for a sidewall, and the sulfur content of the rubber composition for a sidewall and the rubber composition for coating a steel cord satisfies a specific relational expression, and therefore has excellent durability.
- good steering stability, low fuel consumption, and elongation at break can be obtained at the same time.
- FIG. 1 is a diagram schematically showing the periphery of the sidewall portion.
- the pneumatic tire of the present invention has a sidewall and a case, and the sidewall has a butadiene rubber content of 30 to 70% by mass in 100% by mass of the rubber component, and a sulfur content relative to 100 parts by mass of the rubber component.
- a rubber composition for a sidewall wherein the rubber composition is greater than 1.29 parts by weight and less than 2.30 parts by weight
- the case is formed by coating a steel cord with a rubber composition for coating a steel cord.
- the sulfur content of the rubber composition for coating a steel cord satisfies the following relational expression.
- coated and the rubber composition for sidewalls all means content in the rubber composition before vulcanization.
- the chemical content contained in the steel cord coating rubber composition and the sidewall rubber composition is the same as that of the chemical contained in the steel cord coating unvulcanized rubber composition and the sidewall unvulcanized rubber composition.
- the theoretical content means the amount of chemicals added when preparing the unvulcanized rubber composition. 2.70 ⁇ (Sulfur content with respect to 100 parts by mass of rubber component of steel cord covering rubber composition) ⁇ (Sulfur content with respect to 100 parts by mass of rubber component of rubber composition for sidewall) ⁇ 4.20
- the case is generally constituted by a member obtained by coating a fiber cord with a rubber composition for covering a fiber cord.
- a member in which a steel cord is coated with a rubber composition for coating a steel cord is used as a case.
- the amount of sulfur necessary for bonding steel cord covering rubber to the steel cord plating layer is about 1.5 times or more of the amount of sulfur required for bonding fiber cord covering rubber to the fiber cord. Therefore, as in the case of the pneumatic tire of the present invention, when the case is a member in which the steel cord is coated with the rubber composition for coating the steel cord, there is a large difference in sulfur concentration between the case and the sidewall. Prone.
- FIG. 1 schematically shows a state in which sulfur migrates from a case having a large amount of sulfur to a sidewall having a small amount of sulfur, and a sulfur distribution predicted by the sulfur migration. As shown in the predicted distribution map of sulfur, there is a concentration gradient of sulfur in the sidewall rubber, and the boundary with the case has the largest amount of sulfur.
- the sidewall in the tire axial direction It is presumed that the amount of sulfur gradually decreases toward the central portion of the width, the amount of sulfur is the lowest in the vicinity of the central portion, and the sulfur amount gradually increases again toward the sidewall surface due to bloom.
- the vulcanization temperature is lower than that for passenger car tires, the transition of sulfur is significant even in heavy-duty tires that have a thick tire gauge and are easily vulcanized for a long time.
- halogenated butyl rubber is preferably used for the inner liner that is expected to have good air permeability. Since this halogenated butyl rubber has a tight polymer form, it does not accept sulfur element having a strong polarity as much as diene rubber, and it is assumed that there is almost no sulfur transfer from the case toward the inner liner.
- the crosslink density of the side wall rubber increases, and the side wall rubber's crack growth resistance and elongation at break are greatly deteriorated. Separation is likely to occur, and durability is greatly deteriorated. Furthermore, during vulcanization and use of the tire, the amount of sulfur on the sidewall rubber surface is greater than the amount of sulfur in the sidewall rubber, and a hard layer is formed on the surface of the sidewall rubber, resulting in crack growth resistance. The durability is lowered.
- the sulfur content of the rubber composition for the sidewall and the rubber composition for coating the steel cord satisfies the above relational expression, and the rubber composition for the sidewall has a specific amount of butadiene rubber and sulfur. Because it is contained, it is possible to adjust the amount of sulfur movement to an appropriate amount by suppressing the movement of sulfur, and good durability can be obtained while ensuring good steering stability, low fuel consumption, and elongation at break .
- the pneumatic tire of the present invention has a sidewall and a case.
- the case is a member made of a steel cord and a steel cord-coated rubber layer, and is also called a carcass. Specifically, for example, the member shown in FIG. 1 and the like of JP 2010-043180 A.
- the side wall is a member arranged on the outside of the case, and specifically, for example, a member shown in FIG. 1 of Japanese Patent Application Laid-Open No. 2010-043180.
- the sidewall is made of a rubber composition for a sidewall, and the case is formed by coating a steel cord with a rubber composition for coating a steel cord.
- the sulfur content of the rubber composition for a sidewall and the rubber composition for coating a steel cord satisfies the following relational expression.
- durability of a pneumatic tire can be improved suitably.
- the adhesion between the steel cord and the steel cord covering rubber is lowered, and the durability is lowered.
- the crosslinking density of the sidewall is increased, crack growth resistance is lowered, and durability is lowered.
- content of sulfur means the total content of the pure sulfur content of the vulcanizing agent mix
- the pure sulfur content means, for example, a sulfur content contained in oil-containing sulfur when oil-containing sulfur is used as a vulcanizing agent, and also contains a sulfur atom as the vulcanizing agent.
- a compound for example, an alkylphenol / sulfur chloride condensate
- it means the elemental sulfur contained in the compound.
- the lower limit of the relational expression is preferably 2.80.
- the upper limit of the relational expression is preferably 3.70, more preferably 3.55, and still more preferably 3.40.
- Rubber composition for sidewall Although it does not specifically limit as a vulcanizing agent which can be used for the rubber composition for sidewalls, Sulfur, an alkylphenol, sulfur chloride condensate, etc. can be used conveniently. As the vulcanizing agent, sulfur is preferable.
- sulfur examples include powdered sulfur, precipitated sulfur, colloidal sulfur, insoluble sulfur, and highly dispersible sulfur.
- the sulfur content exceeds 1.29 parts by mass, preferably exceeds 1.40 parts by mass, more preferably 1.50 parts by mass with respect to 100 parts by mass of the rubber component. More, more preferably more than 1.60 parts by mass.
- the amount is 1.29 parts by mass or less, the amount of sulfur inflow from the case increases, and the crack growth resistance, elongation at break, and fuel efficiency of the sidewall rubber are greatly deteriorated. Further, separation is performed on the dip surface in contact with the case. Is likely to occur, and the durability is greatly deteriorated. In addition, sufficient steering stability cannot be obtained. Further, the case has insufficient sulfur, the adhesion with the steel cord is lowered, and the durability is lowered.
- this content is less than 2.30 mass parts, Preferably it is less than 2.20 mass parts.
- the amount is 2.30 parts by mass or more, elongation at break (particularly, elongation at break after thermal aging), crack growth resistance deteriorates, and durability deteriorates.
- Butadiene rubber is used for the rubber composition for the sidewall.
- the BR is not particularly limited.
- BR 1220 manufactured by Nippon Zeon Co., Ltd., BR150B manufactured by Ube Industries, Ltd.
- high cis content BR, 1 such as VCR412, VCR617 manufactured by Ube Industries, Ltd.
- SPB syndiotactic polybutadiene crystals
- SPB syndiotactic polybutadiene crystals
- BR with a high vinyl content such as Europrene BR HV80 manufactured by Polymeri Europa
- BR rare earth BR
- tin-modified butadiene rubber modified with a tin compound
- tin-modified BR tin-modified butadiene rubber
- BR including BR and SPB is preferable, and BR including SPB is more preferable.
- the rare earth element-based catalyst used for the synthesis of the rare earth-based BR known catalysts can be used, for example, a lanthanum series rare earth element compound, an organoaluminum compound, an aluminoxane, a halogen-containing compound, and a catalyst containing a Lewis base as necessary Is mentioned.
- a lanthanum series rare earth element compound an organoaluminum compound, an aluminoxane, a halogen-containing compound, and a catalyst containing a Lewis base as necessary Is mentioned.
- an Nd-based catalyst using a neodymium (Nd) -containing compound as a lanthanum series rare earth element compound is particularly preferable.
- Examples of the lanthanum series rare earth element compounds include halides, carboxylates, alcoholates, thioalcolates, amides, and the like of rare earth metals having an atomic number of 57 to 71.
- the use of an Nd-based catalyst is preferable in that a BR having a high cis content and a low vinyl content can be obtained.
- the organoaluminum compound is represented by AlR a R b R c (wherein R a , R b and R c are the same or different and each represents hydrogen or a hydrocarbon group having 1 to 8 carbon atoms). Things can be used.
- the aluminoxane include a chain aluminoxane and a cyclic aluminoxane.
- halogen-containing compound examples include AlX k R d 3-k (wherein X is a halogen, R d is an alkyl group having 1 to 20 carbon atoms, an aryl group or an aralkyl group, and k is 1, 1.5, 2 or 3)
- the Lewis base is used for complexing a lanthanum series rare earth element compound, and acetylacetone, ketone, alcohol and the like are preferably used.
- the rare earth element-based catalyst may be used in the state of being dissolved in an organic solvent (n-hexane, cyclohexane, n-heptane, toluene, xylene, benzene, etc.) during the polymerization of butadiene, silica, magnesia, magnesium chloride, etc. These may be used by being supported on a suitable carrier.
- the polymerization conditions may be either solution polymerization or bulk polymerization, the preferred polymerization temperature is ⁇ 30 to 150 ° C., and the polymerization pressure may be arbitrarily selected depending on other conditions.
- the rare earth-based BR preferably has a ratio (Mw / Mn) of a weight average molecular weight (Mw) to a number average molecular weight (Mn) of 1.2 or more, more preferably 1.5 or more. If it is less than 1.2, the workability tends to deteriorate significantly.
- the Mw / Mn is preferably 5 or less, more preferably 4 or less. If it exceeds 5, the effect of improving the wear resistance tends to decrease.
- the Mw of the rare earth BR is preferably 300,000 or more, more preferably 500,000 or more, and preferably 1,500,000 or less, more preferably 1,200,000 or less. Further, the Mn of the rare earth-based BR is preferably 100,000 or more, more preferably 150,000 or more, and preferably 1,000,000 or less, more preferably 800,000 or less. When Mw or Mn is less than the lower limit, the wear resistance tends to decrease or the fuel efficiency tends to deteriorate. When the upper limit is exceeded, there is a concern about deterioration of workability.
- Mw and Mn are values converted from standard polystyrene using a gel permeation chromatograph (GPC).
- the cis content of the rare earth BR is preferably 90% by mass or more, more preferably 93% by mass or more, and still more preferably 95% by mass or more. If it is less than 90% by mass, the wear resistance and fuel efficiency may be reduced.
- the vinyl content of the rare earth BR is preferably 1.8% by mass or less, more preferably 1.0% by mass or less, still more preferably 0.5% by mass or less, and particularly preferably 0.3% by mass or less. If it exceeds 1.8% by mass, the wear resistance may be reduced.
- the vinyl content (1,2-bonded butadiene unit amount) and cis content (cis-1,4-bonded butadiene unit amount) of the rare earth BR can be measured by infrared absorption spectrum analysis.
- the SPB-containing BR those widely used in the tire industry can be used, and those in which 1,2-syndiotactic polybutadiene crystals are chemically bonded to BR and dispersed are preferable.
- the 1,2-syndiotactic polybutadiene crystals contained in the extrusion direction By arranging the 1,2-syndiotactic polybutadiene crystals contained in the extrusion direction, a sufficient complex elastic modulus in the tire circumferential direction can be obtained, and the rigidity can be improved. Thereby, good steering stability can be obtained.
- the SPB-containing BR island structure is suitably suppressed in the growth of cracks, and excellent crack growth resistance can be obtained, whereby the durability can be preferably improved.
- the melting point of 1,2-syndiotactic polybutadiene crystals is preferably 180 ° C. or higher, more preferably 190 ° C. or higher. If the temperature is less than 180 ° C., the 1,2-syndiotactic polybutadiene crystal melts when kneaded with rubber, and the rigidity may decrease. Moreover, this melting
- the content of 1,2-syndiotactic polybutadiene crystals is preferably 2.5% by mass or more, more preferably 10% by mass or more. If it is less than 2.5% by mass, the durability may not be sufficiently improved.
- the content is preferably 20% by mass or less, more preferably 18% by mass or less, and still more preferably 15% by mass or less. When it exceeds 20% by mass, the SPB-containing BR becomes difficult to disperse in the rubber composition, and the durability tends to decrease.
- the content of BR in 100% by mass of the rubber component is 30% by mass or more. If it is less than 30% by mass, sufficient handling stability, low fuel consumption, elongation at break after heat aging and durability cannot be obtained.
- the BR content is 70% by mass or less, preferably 50% by mass or less. If it exceeds 70 mass%, sufficient elongation at break, elongation at break after heat aging, and durability cannot be obtained. When the BR content is within the above range, good durability can be obtained while ensuring good handling stability, low fuel consumption, and elongation at break.
- the rubber component that can be used in the sidewall rubber composition other than BR is not particularly limited.
- natural rubber NR
- isoprene rubber IR
- liquid isoprene rubber L-IR
- styrene butadiene rubber SBR
- Diene rubbers such as styrene isoprene butadiene rubber (SIBR), chloroprene rubber (CR), and acrylonitrile butadiene rubber (NBR).
- a rubber component may be used independently and may use 2 or more types together.
- NR, IR, L-IR, and SBR are preferred because good durability can be obtained while ensuring good steering stability, low fuel consumption, elongation at break, and crack growth resistance.
- NR and IR are more preferable, and NR is more preferable.
- the NR is not particularly limited, and for example, those commonly used in the tire industry such as SIR20, RSS # 3, TSR20, and the like can be used.
- the IR is not particularly limited, and for example, IR2200 and the like that are common in the tire industry can be used.
- the total content of NR, IR, L-IR, and SBR (preferably the total content of NR and IR, more preferably the content of NR) in 100% by mass of the rubber component is preferably 30% by mass or more, more Preferably it is 50 mass% or more. If it is less than 30% by mass, sufficient elongation at break, elongation at break after heat aging, and durability tend not to be obtained.
- the content is preferably 70% by mass or less. When it exceeds 70% by mass, there is a tendency that sufficient handling stability, low fuel consumption, elongation at break after heat aging, and durability cannot be obtained. When the content is within the above range, good durability can be obtained while ensuring good handling stability, low fuel consumption, and elongation at break.
- C5 petroleum resin, C9 petroleum resin, process oil, vegetable oil, coumarone indene resin and the like can be used as a softening agent.
- C5 petroleum resins are preferable because they are excellent in adhesiveness, elongation at break, and ozone deterioration resistance and are inexpensive.
- the C5 petroleum resin is obtained by polymerizing a C5 (carbon number 5) petroleum hydrocarbon.
- the C5 petroleum hydrocarbon means a C5 fraction (a fraction having 5 carbon atoms) obtained by thermal decomposition of naphtha, and specifically, isoprene, 1,3-pentadiene, dicyclopentadiene.
- diolefins such as piperylene and monoolefins such as 2-methyl-1-butene, 2-methyl-2-butene and cyclopentene.
- the content of the C5-based petroleum resin is preferably 1 to 5 parts by mass, and more preferably 1 to 3 parts by mass for the reason that moderate tackiness and elongation at break are excellent.
- Process oil loosens the polymer and makes it easier to move sulfur.
- the effect of promoting the movement of sulfur by the process oil is greater than other softening agents such as C5 petroleum resins.
- the rubber composition for sidewalls inherently has a relatively low crosslink density, the mobility of chemicals and sulfur is large. Therefore, when the amount of process oil is smaller, the inflow of sulfur from the case can be suppressed.
- the content of the process oil is preferably 10 parts by mass or less, more preferably 5 parts by mass or less, and still more preferably 0.5 parts by mass or less with respect to 100 parts by mass of the rubber component. If it exceeds 10 parts by mass, the inflow amount of sulfur from the case increases, and the durability may decrease.
- Carbon rubber may be blended in the rubber composition for the sidewall.
- the reinforcing property can be enhanced, and the crack growth resistance, durability, handling stability, and UV degradation resistance can be improved.
- Examples of carbon black that can be used include GPF, FEF, HAF, ISAF, and SAF, but are not particularly limited.
- the nitrogen adsorption specific surface area (N 2 SA) of carbon black is preferably 20 m 2 / g or more, and more preferably 60 m 2 / g or more.
- N 2 SA is less than 20 m 2 / g, crack growth resistance, durability, and steering stability may be reduced.
- N 2 SA of carbon black is preferably 120 m 2 / g or less, and more preferably 100 m 2 / g or less. If N 2 SA exceeds 120 m 2 / g, sufficient fuel economy and processability may not be obtained.
- the nitrogen adsorption specific surface area of carbon black is determined according to JIS K 6217-2: 2001.
- the content of carbon black is preferably 10 parts by mass or more, more preferably 20 parts by mass or more with respect to 100 parts by mass of the rubber component. If it is less than 10 parts by mass, sufficient reinforcing properties cannot be obtained, and crack growth resistance, durability, and steering stability tend to deteriorate. Further, the carbon black content is preferably 100 parts by mass or less, more preferably 70 parts by mass or less, and still more preferably 50 parts by mass or less with respect to 100 parts by mass of the rubber component. If it exceeds 100 parts by mass, the fuel efficiency may be deteriorated.
- the rubber composition includes a compounding agent conventionally used in the rubber industry, for example, a filler such as silica, a wax, an antioxidant, an antioxidant, a vulcanization accelerator (stearic acid, Zinc oxide or the like), a hybrid crosslinking agent (such as HTS or PK900 manufactured by Flexis), a vulcanization accelerator, or the like may be contained.
- a filler such as silica, a wax, an antioxidant, an antioxidant, a vulcanization accelerator (stearic acid, Zinc oxide or the like), a hybrid crosslinking agent (such as HTS or PK900 manufactured by Flexis), a vulcanization accelerator, or the like may be contained.
- vulcanization accelerator examples include guanidine, aldehyde-amine, aldehyde-ammonia, thiazole, sulfenamide, thiourea, thiuram, dithiocarbamate, and zanddate compounds. These vulcanization accelerators may be used alone or in combination of two or more. Of these, sulfenamide-based vulcanization accelerators [N-tert-butyl-2-benzothiazolylsulfenamide (TBBS), N-cyclohexyl are preferred from the viewpoint of dispersibility in rubber and stability of vulcanization properties.
- TBBS N-tert-butyl-2-benzothiazolylsulfenamide
- CBS -2-benzothiazolylsulfenamide
- DCBS N-dicyclohexyl-2-benzothiazolylsulfenamide
- DM di-2-benzothiazolyl disulfide
- the blending amount of the vulcanization accelerator is preferably 0.3 parts by mass or more, more preferably 0.5 parts by mass or more with respect to 100 parts by mass of the rubber component. Moreover, this compounding quantity becomes like this. Preferably it is 0.8 mass part or less, More preferably, it is 0.7 mass part or less.
- the blending amount of the vulcanization accelerator is within the above range, suitable crosslinking density and crack growth resistance as a sidewall rubber can be obtained, and the amount of sulfur transfer can be adjusted to an appropriate amount, and the effects of the present invention can be achieved. More suitably obtained.
- the rubber composition for a sidewall As a method for producing the rubber composition for a sidewall, a known method can be used. For example, it can be produced by a method of kneading the above components using a rubber kneading apparatus such as an open roll or a Banbury mixer.
- a rubber kneading apparatus such as an open roll or a Banbury mixer.
- Rubber composition for steel cord coating Although it does not specifically limit as a rubber component which can be used for the rubber composition for steel cord coating, The diene rubber similar to the rubber composition for sidewalls can be used. A rubber component may be used independently and may use 2 or more types together. Among these, NR is preferable because good durability can be obtained while ensuring good steering stability, low fuel consumption, and elongation at break.
- the content of NR in 100% by mass of the rubber component is preferably 50% by mass or more, more preferably 80% by mass or more, and still more preferably 100% by mass.
- the content of NR is the above amount, good durability can be obtained while ensuring good handling stability, low fuel consumption, and elongation at break.
- the vulcanizing agent that can be used is not particularly limited, and the same vulcanizing agent as that used for the sidewall rubber composition can be used.
- the sulfur content is preferably more than 3.0 parts by mass, more preferably more than 4.50 parts by mass, and still more preferably 4. Over 80 parts by weight. If it is 3.0 parts by mass or less, the adhesion with the steel cord is lowered, and the durability may be lowered. In addition, sufficient fuel economy and elongation at break may not be obtained. Further, the content is preferably less than 6.00 parts by mass, more preferably less than 5.80 parts by mass, and still more preferably less than 5.30 parts by mass. If it is 6.00 parts by mass or more, elongation at break and crack growth resistance are lowered, and durability is lowered. Moreover, there is a possibility that sufficient fuel efficiency cannot be obtained. If the sulfur content is within the above range, good elongation at break, crack growth resistance, and adhesion to steel cords can be obtained while ensuring good handling stability and low fuel consumption. Good durability is obtained.
- the content of the C5-based petroleum resin is preferably 1 to 5 parts by mass, and more preferably 1 to 3 parts by mass for the reason that moderate tackiness and elongation at break are excellent.
- the content of the process oil is preferably 10 parts by mass or less, more preferably 5 parts by mass or less, and still more preferably 0.5 parts by mass or less with respect to 100 parts by mass of the rubber component. If it exceeds 10 parts by mass, the outflow amount of sulfur from the case increases, and the durability may decrease.
- Carbon rubber may be blended in the steel cord covering rubber composition. By blending carbon black, the reinforcing property can be enhanced, and the durability and steering stability can be improved.
- the nitrogen adsorption specific surface area (N 2 SA) of carbon black is preferably 40 m 2 / g or more, and more preferably 60 m 2 / g or more.
- N 2 SA is less than 40 m 2 / g, durability and steering stability may be reduced.
- N 2 SA of carbon black is preferably 150 meters 2 / g or less, 100 m 2 / g or less is more preferable. If N 2 SA exceeds 150 m 2 / g, the dispersibility is poor and sufficient fuel efficiency may not be obtained.
- the content of carbon black is preferably 10 parts by mass or more, more preferably 20 parts by mass or more with respect to 100 parts by mass of the rubber component. If it is less than 10 parts by mass, sufficient reinforcing properties cannot be obtained, and durability and steering stability tend to deteriorate.
- the carbon black content is preferably 100 parts by mass or less, more preferably 80 parts by mass or less, with respect to 100 parts by mass of the rubber component. If it exceeds 100 parts by mass, the fuel efficiency may be deteriorated.
- the rubber composition for coating a steel cord is preferably blended with an organic acid cobalt for the purpose of improving the adhesion to the steel cord. Since the organic acid cobalt plays a role of crosslinking the rubber and the steel cord, the adhesion between the steel cord and the rubber can be improved by containing the organic acid cobalt.
- organic acid cobalt examples include cobalt stearate, cobalt naphthenate, cobalt neodecanoate, boron 3 neodecanoate cobalt, and abitienate cobalt.
- cobalt stearate is preferable because it is excellent in processability (viscosity) and the vulcanization reaction easily proceeds.
- the content of the organic acid cobalt is preferably 0.05 parts by mass or more and more preferably 0.07 parts by mass or more in terms of cobalt with respect to 100 parts by mass of the rubber component. If it is less than 0.05 parts by mass, the adhesion between the steel cord and the rubber may not be sufficient.
- the content is preferably 0.15 parts by mass or less, more preferably 0.12 parts by mass or less in terms of cobalt. When it exceeds 0.15 mass part, there exists a tendency for oxidation deterioration resistance, crack growth resistance, and durability to deteriorate.
- the rubber composition includes a compounding agent conventionally used in the rubber industry, for example, a filler such as silica, a wax, an antioxidant, an antioxidant, a vulcanization accelerator (stearic acid, Zinc oxide or the like), a vulcanization accelerator or the like may be contained.
- a filler such as silica, a wax, an antioxidant, an antioxidant, a vulcanization accelerator (stearic acid, Zinc oxide or the like), a vulcanization accelerator or the like may be contained.
- the content of zinc oxide is preferably 3 to 20 parts by mass, more preferably 6 to 12 parts by mass with respect to 100 parts by mass of the rubber component.
- the zinc oxide content is within the above range, good handling stability and low fuel consumption can be ensured, while good elongation at break, resistance to crack growth, and adhesion to steel cords can be obtained. Good durability can be obtained.
- the same rubber composition as that for the sidewall rubber composition can be used, but DCBS and TBSI are more preferable because of excellent adhesion to the cord.
- the blending amount of the vulcanization accelerator is preferably 0.3 parts by mass or more, more preferably 0.8 parts by mass or more with respect to 100 parts by mass of the rubber component. Moreover, this compounding quantity becomes like this. Preferably it is 2.0 mass parts or less, More preferably, it is 1.2 mass parts or less.
- the blending amount of the vulcanization accelerator is within the above range, a suitable crosslinking density as a steel cord coating rubber can be obtained, the amount of sulfur transfer can be adjusted to an appropriate amount, and the effects of the present invention are more suitably achieved. can get.
- the same method as that for the sidewall rubber composition can be used.
- the pneumatic tire of the present invention is produced by a usual method using the rubber composition. That is, the rubber composition containing various additives as required is formed into the shape of each member of the tire at the unvulcanized stage (in the case of a sidewall, the rubber composition for the sidewall is In the case of unvulcanized, a sheet-like steel cord covering rubber composition is pressure-coated on the steel cord from the top and bottom, and extruded according to the shape of the case), and then a normal method on a tire molding machine.
- the tire is manufactured by molding with, bonding together with other tire members, forming an unvulcanized tire, and then vulcanizing by heating and pressing in a vulcanizer (preferably a dome type vulcanizer). Can do.
- a vulcanizer preferably a dome type vulcanizer
- the temperature of the vulcanization mold when vulcanizing the tire or the steam filling temperature of the vulcanizer is preferably 130 to 158 ° C, more preferably 130 to 155 ° C, still more preferably 130 to 152 ° C, particularly preferably. Is 130-145 ° C, most preferably 130-140 ° C.
- the reversion refers to a phenomenon in which a sulfur bridge once formed is cleaved and sulfur hangs in a pendant form on one polymer chain, or a molecular chain of the polymer itself is cleaved.
- the steel cord is not particularly limited, and examples thereof include a single-twisted steel cord having a 1 ⁇ n configuration and a layer-twisted steel cord having a k + m configuration.
- the single stranded steel cord having a 1 ⁇ n configuration is a one-layer stranded steel cord obtained by twisting n filaments.
- the k + m layer-twisted steel cord is a steel cord having a two-layer structure with different twist directions and twist pitches, and having k filaments in the inner layer and m filaments in the outer layer.
- n is an integer of 1 to 27
- k is an integer of 1 to 10
- m is an integer of 1 to 3.
- the surface of the steel cord is preferably plated with brass (brass), Zn or the like in order to improve initial adhesion to the rubber composition.
- the pneumatic tire of the present invention is used as a tire for passenger cars, a heavy load tire, and the like, and particularly preferably used as a heavy load tire.
- the heavy load tire in this specification is a tire particularly excellent in durability, and examples thereof include industrial tires used for industrial vehicles such as truck and bus tires and heavy machinery.
- industrial tires used for industrial vehicles such as truck and bus tires and heavy machinery.
- all-steel tires are usually used in which the cord used for the case and breaker is a steel cord.
- NR TSR20 IR: IR2200 manufactured by JSR Corporation BR1: BR150B manufactured by Ube Industries, Ltd. (cis content: 97% by mass)
- BR3 VCR450 manufactured by Ube Industries, Ltd.
- BR including SPB, content of 1,2-syndiotactic polybutadiene crystal: 3.8% by mass
- BR4 VCR412 manufactured by Ube Industries, Ltd. (BR including SPB, content of 1,2-syndiotactic polybutadiene crystal: 12% by mass)
- Carbon black 1 Dia Black H (N330, N 2 SA: 78 m 2 / g) manufactured by Mitsubishi Chemical Corporation
- C5 resin Marukaretsu T-100AS (C5 petroleum resin) manufactured by Maruzen Petrochemical Industry Co., Ltd.
- Zinc oxide Zinc Hua 1 manufactured by Mitsui Mining & Smelting Co., Ltd.
- Anti-aging agent Antigen 6C (N- (1,3-dimethylbutyl) -N′-phenyl-p-phenylenediamine) manufactured by Sumitomo Chemical Co., Ltd. 10% oil-containing insoluble sulfur: Seimi OT manufactured by Nihon Kiboshi Kogyo Co., Ltd.
- TBBS Noxeller NS (N-tert-butyl-2-benzothiazolylsulfenamide) manufactured by Ouchi Shinsei Chemical Industry Co., Ltd.
- Carbon Black 2 Dia Black LH (N326, N 2 SA: 84 m 2 / g) manufactured by Mitsubishi Chemical Corporation Cobalt stearate: cost-F (cobalt content: 9.5% by mass) manufactured by Dainippon Ink & Chemicals, Inc.
- Insoluble sulfur containing 20% oil Mucron OT-20 manufactured by Shikoku Kasei Co., Ltd.
- DCBS Noxeller DZ (N, N-dicyclohexyl-2-benzothiazolylsulfenamide) manufactured by Ouchi Shinsei Chemical Industry Co., Ltd.
- the obtained unvulcanized rubber composition was formed into a steel cord (3 + 9 + 15 / 0.175) after forming the thickness of the sheet after topping to 0.8 mm.
- a rubber composition for a sidewall it was molded into a sidewall shape (the thickness of the sidewall rubber at the maximum width portion in the tire axial direction of the tire was 5 mm).
- Steel cord covering rubber composition contains 60 parts by mass of carbon black 2, 1 part by mass of cobalt stearate, 10 parts by mass of zinc oxide, 2 parts by mass of C5 resin and 20% oil per 100 parts by mass of NR
- the amount of insoluble sulfur shown in Tables 1 and 2 (the amounts shown in Tables 1 and 2 indicate pure sulfur content) and 1 part by mass of DCBS were blended.
- test pneumatic tire was allowed to stand in an air-filled oven at 80 ° C. for 3 weeks to obtain a test pneumatic tire after heat aging.
- the maximum width portion in the tire axial direction of the obtained pneumatic tire for test (where the sidewall rubber is the thinnest part (rubber thickness is 5 mm), the part where the vulcanization temperature is most likely to rise, that is, the part where the sulfur migration is most likely to occur
- a sidewall rubber sample was collected from a portion 2 mm inward from the sidewall surface (approximately the middle portion of the width of the sidewall rubber in the tire axial direction (SW central portion)) (see FIG. 1).
- a sidewall rubber sample after heat aging was collected from a test pneumatic tire after heat aging.
- a pneumatic tire having a sidewall and a case the sidewall is made of a rubber composition for a sidewall containing a specific amount of butadiene rubber and sulfur, and the case is coated with a steel cord.
- the pneumatic tire which is coated with the rubber composition for a side wall and in which the sulfur content of the rubber composition for a sidewall and the rubber composition for coating a steel cord satisfies a specific relational expression, is excellent in durability. In addition, good steering stability, low fuel consumption, and elongation at break were obtained at the same time.
- Comparative Examples 1 to 3 durability was inferior because the content of sulfur in the rubber composition for the side wall was small and sulfur easily migrated from the case to the side wall.
- Comparative Examples 4 to 6 durability was inferior because the rubber content for the sidewall had a high sulfur content and the elongation at break after heat aging was inferior.
- Comparative Examples 7 and 8 in which the content of butadiene rubber deviates from a specific amount, the elongation at break after heat aging was inferior, so the durability was inferior.
- Comparative Examples 3 and 9 in which the difference in sulfur content between the rubber composition for the sidewall and the rubber composition for covering the steel cord exceeds 4.20 are inferior in durability because sulfur easily moves from the case to the sidewall. It was.
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Abstract
Description
そして、ケースに使用されるスチールコード被覆用ゴム組成物の硫黄の移動に着目し、スチールコード被覆用ゴム組成物と、ケースの隣接部材であるサイドウォールに使用されるサイドウォール用ゴム組成物の硫黄の含有量が特定の関係式を満たすことにより、作製した空気入りタイヤの耐久性が非常に優れていることを見出し、更に、サイドウォール特有の期待性能に合わせて硫黄量を定めて、本発明を完成させた。
2.70<(スチールコード被覆用ゴム組成物のゴム成分100質量部に対する硫黄の含有量)-(サイドウォール用ゴム組成物のゴム成分100質量部に対する硫黄の含有量)<4.20
2.80<(スチールコード被覆用ゴム組成物のゴム成分100質量部に対する硫黄の含有量)-(サイドウォール用ゴム組成物のゴム成分100質量部に対する硫黄の含有量)<3.70
2.70<(スチールコード被覆用ゴム組成物のゴム成分100質量部に対する硫黄の含有量)-(サイドウォール用ゴム組成物のゴム成分100質量部に対する硫黄の含有量)<4.20
この濃度差を小さくするために、サイドウォールの硫黄量を増量しすぎると、熱老化後の破断時伸びが低下し、疲労により割れが生じやすくなり、耐久性が低下する。一方、サイドウォールの硫黄量が少ないと、ケースとの硫黄の濃度差が大きくなり、ケースの硫黄がサイドウォールに移行する。図1では、硫黄量が多いケースから硫黄量が少ないサイドウォールへ硫黄が移行する様子、及び硫黄の移行により予測される硫黄の分布を模式的に示している。この硫黄の予測分布図のように、サイドウォールゴム中において硫黄の濃度勾配が生じており、ケースとの境界部分が最も硫黄量が多く、ケースとの境界部分から、サイドウォールのタイヤ軸方向の幅の中央部分にかけて硫黄量が徐々に減少し、該中央部分付近で硫黄量が最も低くなっており、ブルームにより、サイドウォール表面にかけて再び硫黄量が徐々に増加するものと推測される。なお、乗用車用タイヤに比べて加硫温度は低いものの、タイヤのゲージが厚く、長時間加硫が行われやすい重荷重用タイヤでも、硫黄の移行が顕著になる。一方、良好な空気透過性を期待されるインナーライナーには、好んで、ハロゲン化ブチルゴムが使用される。このハロゲン化ブチルゴムは、ポリマー形態がタイトであるため、極性の強い硫黄元素を、ジエン系ゴムほど受け入れないため、ケースからインナーライナー方向への硫黄の移行はほとんど起こらないものと推測される。
一方、上記移動により、硫黄が減少することとなるケースでは、スチールコード周辺の硫黄濃度が低下し、スチールコードのメッキ層とスチールコード被覆用ゴム間の硫黄の再結合に働く硫黄が不足し、接着性ひいては耐久性が低下してしまう。
逆に、サイドウォールからケースへ硫黄が移動する場合、移動量が多いとサイドウォールの硬度(Hs)が低下し、操縦安定性が低下する。そして、ケースでは、硫黄量が増加し、スチールコードとの接着性は良くなるものの、ケースの柔軟性が低下し、疲労により割れが生じやすくなり、耐久性が低下する。
ケースとは、スチールコード及びスチールコード被覆ゴム層からなる部材であり、カーカスともいう。具体的には、例えば、特開2010-043180号公報の図1等に示される部材である。
サイドウォールとは、ケースの外側に配された部材であり、具体的には、例えば、特開2010-043180号公報の図1等に示される部材である。
2.70<(スチールコード被覆用ゴム組成物のゴム成分100質量部に対する硫黄の含有量)-(サイドウォール用ゴム組成物のゴム成分100質量部に対する硫黄の含有量)<4.20
なお、本明細書において、硫黄の含有量とは、ゴム組成物に配合される加硫剤の純硫黄分の合計含有量を意味する。ここで、純硫黄分とは、例えば、加硫剤として、オイル含有硫黄を使用する場合には、オイル含有硫黄に含まれる硫黄分を意味し、また、加硫剤として、硫黄原子を含有する化合物(例えば、アルキルフェノール・塩化硫黄縮合物)を使用する場合には、該化合物中に含まれる硫黄元素分を意味する。
上記関係式の上限は、3.70が好ましく、3.55がより好ましく、3.40が更に好ましい。
サイドウォール用ゴム組成物に使用できる加硫剤としては、特に限定されないが、硫黄、アルキルフェノール・塩化硫黄縮合物等を好適に使用できる。加硫剤としては、硫黄が好ましい。
なかでも、良好な操縦安定性、低燃費性、破断時伸びを確保しつつ、良好な耐久性が得られるという理由から、シス含有量が95質量%以上の高シス含有量のBR、希土類系BR、SPBを含むBRが好ましく、SPBを含むBRがより好ましい。
なお、本発明において、Mw、Mnは、ゲルパーミエーションクロマトグラフ(GPC)を用い、標準ポリスチレンより換算した値である。
なお、本発明において、希土類系BRのビニル含量(1,2-結合ブタジエン単位量)及びシス含量(シス-1,4-結合ブタジエン単位量)は、赤外吸収スペクトル分析法によって測定できる。
C5系石油樹脂の含有量は、適度な粘着性、破断時伸びに優れるという理由から、1~5質量部が好ましく、1~3質量部がより好ましい。
なお、本明細書において、カーボンブラックのチッ素吸着比表面積は、JIS K 6217-2:2001によって求められる。
スチールコード被覆用ゴム組成物に使用できるゴム成分としては、特に限定されないが、サイドウォール用ゴム組成物と同様のジエン系ゴムを使用できる。ゴム成分は、単独で用いてもよく、2種以上を併用してもよい。なかでも、良好な操縦安定性、低燃費性、破断時伸びを確保しつつ、良好な耐久性が得られるという理由から、NRが好ましい。
C5系石油樹脂の含有量は、適度な粘着性、破断時伸びに優れるという理由から、1~5質量部が好ましく、1~3質量部がより好ましい。
加硫促進剤の配合量は、ゴム成分100質量部に対して、好ましくは0.3質量部以上、より好ましくは0.8質量部以上である。また、該配合量は、好ましくは2.0質量部以下、より好ましくは1.2質量部以下である。加硫促進剤の配合量が上記範囲内であると、スチールコード被覆用ゴムとしての好適な架橋密度が得られ、硫黄の移動量を適度な量に調整でき、本発明の効果がより好適に得られる。
NR:TSR20
IR:JSR(株)製のIR2200
BR1:宇部興産(株)製のBR150B(シス含有量:97質量%)
BR2:ランクセス(株)製のCB24(Nd系触媒を用いて合成したBR、Tg:-116℃、シス含量:96質量%、ビニル含量:0.7質量%、ML1+4(100℃):45、Mw/Mn:2.69、Mw:50万、Mn:18.6万)
BR3:宇部興産(株)製のVCR450(SPBを含むBR、1,2-シンジオタクチックポリブタジエン結晶の含有量:3.8質量%)
BR4:宇部興産(株)製のVCR412(SPBを含むBR、1,2-シンジオタクチックポリブタジエン結晶の含有量:12質量%)
カーボンブラック1:三菱化学(株)製のダイアブラックH(N330、N2SA:78m2/g)
C5レジン:丸善石油化学工業(株)製のマルカレッツT-100AS(C5系石油樹脂)
酸化亜鉛:三井金属鉱業(株)製の亜鉛華1号
ステアリン酸:日油(株)製のステアリン酸「椿」
老化防止剤:住友化学(株)製のアンチゲン6C(N-(1,3-ジメチルブチル)-N’-フェニル-p-フェニレンジアミン)
10%オイル含有不溶性硫黄:日本乾溜工業(株)製のセイミOT
TBBS:大内新興化学工業(株)製のノクセラーNS(N-tert-ブチル-2-ベンゾチアゾリルスルフェンアミド)
カーボンブラック2:三菱化学(株)製のダイアブラックLH(N326、N2SA:84m2/g)
ステアリン酸コバルト:大日本インキ化学工業(株)製のcost-F(コバルト含有量:9.5質量%)
20%オイル含有不溶性硫黄:四国化成(株)製のミュークロンOT-20
DCBS:大内新興化学工業(株)製のノクセラーDZ(N,N-ジシクロヘキシル-2-ベンゾチアゾリルスルフェンアミド)
サイドウォール用ゴム組成物については表1、2に示す配合内容、スチールコード被覆用ゴム組成物については、表1、2及び下記に示す配合内容に従い、バンバリーミキサーを用いて、加硫剤及び加硫促進剤以外の材料を160℃の条件下で5分間混練りし、混練り物を得た。次に、得られた混練り物に硫黄及び加硫促進剤を添加し、オープンロールを用いて、105℃の条件下で3分間練り込み、未加硫ゴム組成物を得た。
次に、得られた未加硫ゴム組成物を、スチールコード被覆用ゴム組成物の場合は、トッピング後のシートの厚みを0.8mmに成形後、該シートをスチールコード(3+9+15/0.175)に被覆してケースの形状に、サイドウォール用ゴム組成物の場合はサイドウォールの形状(タイヤのタイヤ軸方向の最大幅部のサイドウォールゴムの厚みを5mmとした)に成形した。そして、表1、2に示す組み合わせに従い、他のタイヤ部材と貼り合わせ、ドーム型加硫機で表1、2に示す温度で12分間プレス加硫することにより、試験用空気入りタイヤ(オールスチールラジアルタイヤ)(295/80R22.5)を作製した。
スチールコード被覆用ゴム組成物は、NR100質量部に対して、カーボンブラック2を60質量部、ステアリン酸コバルトを1質量部、酸化亜鉛を10質量部、C5レジンを2質量部、20%オイル含有不溶性硫黄を表1、2に示す量(表1、2に示す量は、純硫黄分を示す)、DCBSを1質量部配合した。
同様にして、熱老化後の試験用空気入りタイヤから、熱老化後のサイドウォールゴムサンプルを採取した。
サイドウォールゴムサンプルについて、加熱炉で硫黄(S)を二酸化硫黄(SO2)に変換し、炭素硫黄分析計を用いて、赤外線検出により化学分析(硫黄の定量)を行った。
岩本製作所(株)製の粘弾性スペクトロメーターを用いて、70℃、初期歪10%、動歪み2%、周波数10Hzの条件下で、各サイドウォールゴムサンプルの損失正接(tanδ)及び複素弾性率(E*)を測定した。
tanδが小さいほど、転がり抵抗が低く、低燃費性に優れることを示す。E*が大きいほど、操縦安定性に優れることを示す。
サイドウォールゴムサンプルからなる3号ダンベル型試験片を用いて、JIS K 6251「加硫ゴム及び熱可塑性ゴム-引張特性の求め方」に準じて、室温にて引張試験を実施し、破断時伸びEB(%)を測定した。EBが大きいほど、破断時伸びに優れることを示す。同様に、熱老化後のサイドウォールゴムサンプルについても、熱老化後の破断時伸びEB(%)を測定した。熱老化後の破断時伸びが大きいほど、熱老化後の破断時伸びに優れることを示す。
熱老化後の試験用空気入りタイヤのタイヤ軸方向の最大幅部のサイドウォールゴムに、カッターナイフを用いて、幅2mm、深さ0.2mmの亀裂を45度方向に、周上20箇所設け、JIS規格の最大荷重(最大内圧条件)の140%荷重の条件下で、前記タイヤを速度80km/hで8万kmドラム走行させ、亀裂の成長度合いを指数化した。なお、亀裂は、斜め45度方向に伸展する場合が多いが、バラツキがあるため、20箇所の評価結果を平均して、基準タイヤ(実施例7)の耐亀裂成長性指数を100とし、各タイヤの耐亀裂成長性を指数表示した。なお、耐亀裂成長性指数が大きいほど、耐久性に優れ、良好であることを示す。
Claims (7)
- サイドウォール及びケースを有する空気入りタイヤであって、
サイドウォールが、ゴム成分100質量%中のブタジエンゴムの含有量が30~70質量%で、ゴム成分100質量部に対する硫黄の含有量が1.29質量部を超え2.30質量部未満であるサイドウォール用ゴム組成物からなり、
ケースが、スチールコードをスチールコード被覆用ゴム組成物で被覆されてなり、
サイドウォール用ゴム組成物及びスチールコード被覆用ゴム組成物の硫黄の含有量が下記関係式を満たす空気入りタイヤ。
2.70<(スチールコード被覆用ゴム組成物のゴム成分100質量部に対する硫黄の含有量)-(サイドウォール用ゴム組成物のゴム成分100質量部に対する硫黄の含有量)<4.20 - サイドウォール用ゴム組成物及びスチールコード被覆用ゴム組成物の硫黄の含有量が下記関係式を満たす請求項1記載の空気入りタイヤ。
2.80<(スチールコード被覆用ゴム組成物のゴム成分100質量部に対する硫黄の含有量)-(サイドウォール用ゴム組成物のゴム成分100質量部に対する硫黄の含有量)<3.70 - 加硫金型温度、又は、加硫機のスチーム充填温度が130~158℃である請求項1又は2記載の空気入りタイヤ。
- サイドウォール用ゴム組成物のゴム成分100質量%中の天然ゴム、イソプレンゴム、液状イソプレンゴム、及びスチレンブタジエンゴムの合計含有量が30~70質量%である請求項1~3のいずれかに記載の空気入りタイヤ。
- サイドウォール用ゴム組成物が、ブタジエンゴムとして、1,2-シンジオタクチックポリブタジエン結晶を含むブタジエンゴムを含む請求項1~4のいずれかに記載の空気入りタイヤ。
- サイドウォール用ゴム組成物の加硫促進剤の含有量が、ゴム成分100質量部に対して、0.3~0.8質量部である請求項1~5のいずれかに記載の空気入りタイヤ。
- 重荷重用タイヤである請求項1~6のいずれかに記載の空気入りタイヤ。
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CN201280035523.9A CN103717662B (zh) | 2011-08-23 | 2012-08-20 | 充气轮胎 |
BR112014004208A BR112014004208A2 (pt) | 2011-08-23 | 2012-08-20 | pneumático |
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JP2012017256A JP5111670B1 (ja) | 2011-08-23 | 2012-01-30 | 空気入りタイヤ |
JP2012-017256 | 2012-01-30 |
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Cited By (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP2013010923A (ja) * | 2011-05-27 | 2013-01-17 | Sumitomo Rubber Ind Ltd | 空気入りタイヤ |
WO2014178336A1 (ja) * | 2013-04-30 | 2014-11-06 | 住友ゴム工業株式会社 | 空気入りタイヤ |
Families Citing this family (9)
Publication number | Priority date | Publication date | Assignee | Title |
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JP5925527B2 (ja) * | 2012-02-29 | 2016-05-25 | 東洋ゴム工業株式会社 | タイヤサイドウォール用ゴム組成物及び空気入りタイヤ |
JP6195243B2 (ja) * | 2013-11-01 | 2017-09-13 | 住友ゴム工業株式会社 | 空気入りタイヤ |
CN104311908A (zh) * | 2014-11-20 | 2015-01-28 | 三角轮胎股份有限公司 | 含1,2-间规聚丁二烯的胎侧橡胶组合物 |
JP2018109198A (ja) * | 2018-03-19 | 2018-07-12 | 住友ゴム工業株式会社 | タイヤ |
JP7196446B2 (ja) * | 2018-07-20 | 2022-12-27 | 横浜ゴム株式会社 | 添加剤の評価方法、ゴム組成物、金属-ゴム複合体、空気入りタイヤ、及び空気入りタイヤの製造方法 |
JP7368698B2 (ja) * | 2019-08-23 | 2023-10-25 | 横浜ゴム株式会社 | 重荷重用空気入りタイヤ |
JP7360021B2 (ja) * | 2019-08-26 | 2023-10-12 | 横浜ゴム株式会社 | 重荷重用空気入りタイヤ |
JP7401734B2 (ja) * | 2019-09-13 | 2023-12-20 | 横浜ゴム株式会社 | 重荷重用空気入りタイヤ |
CN111205522A (zh) * | 2020-02-23 | 2020-05-29 | 湖北玲珑轮胎有限公司 | 一种全钢子午线轮胎钢丝胎体帘线覆胶组合物 |
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US5462979A (en) * | 1994-09-28 | 1995-10-31 | The Goodyear Tire & Rubber Company | Sulfur cured rubber composition containing epoxidized natural rubber and carboxylated nitrile rubber |
JP3683373B2 (ja) * | 1997-03-17 | 2005-08-17 | 住友ゴム工業株式会社 | 空気入りタイヤ |
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- 2012-01-30 JP JP2012017256A patent/JP5111670B1/ja active Active
- 2012-04-20 CN CN2012101296140A patent/CN102950979A/zh active Pending
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- 2012-08-20 CN CN201280035523.9A patent/CN103717662B/zh not_active Expired - Fee Related
- 2012-08-20 WO PCT/JP2012/070952 patent/WO2013027690A1/ja active Application Filing
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JP2006256358A (ja) * | 2005-03-15 | 2006-09-28 | Bridgestone Corp | 空気入りタイヤ |
JP2007269259A (ja) * | 2006-03-31 | 2007-10-18 | Yokohama Rubber Co Ltd:The | 空気入りラジアルタイヤ |
JP2010058782A (ja) * | 2008-08-07 | 2010-03-18 | Sumitomo Rubber Ind Ltd | タイヤ |
JP2010188955A (ja) * | 2009-02-20 | 2010-09-02 | Sumitomo Rubber Ind Ltd | タイヤ |
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JP2013010923A (ja) * | 2011-05-27 | 2013-01-17 | Sumitomo Rubber Ind Ltd | 空気入りタイヤ |
WO2014178336A1 (ja) * | 2013-04-30 | 2014-11-06 | 住友ゴム工業株式会社 | 空気入りタイヤ |
JP5981645B2 (ja) * | 2013-04-30 | 2016-08-31 | 住友ゴム工業株式会社 | 空気入りタイヤ |
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CN103717662B (zh) | 2015-12-09 |
CN102950979A (zh) | 2013-03-06 |
BR112014004208A2 (pt) | 2017-03-14 |
JP5111670B1 (ja) | 2013-01-09 |
CN103717662A (zh) | 2014-04-09 |
JP2013060184A (ja) | 2013-04-04 |
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