JP2021195442A - Tire for heavy load - Google Patents

Abstract

To provide a tire for heavy load excellent in an on-ice start performance.SOLUTION: There is provided a tire for heavy load having a tread composed of a rubber composition which includes an isoprene rubber and a butadiene rubber and in which tanδ at -10°C under a condition in a following shear mode satisfies a following formula (1). The formula (1) is: tanδ≤0.48 at 0.38≤-10°C, and in the (shear mode), stress is 0.5 MPa, a frequency is 10 Hz, and a measured temperature of tanδ is -10°C.SELECTED DRAWING: None

Description

The present invention relates to a heavy load tire.

In recent years, performance on ice and snow has been required as an important performance of heavy-duty tires for trucks, buses, etc., and in particular, improvement in drive performance (starting performance on ice) on ice road surfaces is desired (see Patent Document 1). ..

Japanese Unexamined Patent Publication No. 2010-168427

An object of the present invention is to solve the above-mentioned problems and to provide a heavy-duty tire having excellent starting performance on ice.

The present inventor clarifies the frequency that the tread rubber inputs from the icy road surface when starting on the icy road surface from the relationship between the icy road surface shape and the speed at the time of starting, and reflects the condition in the viscoelasticity measurement condition to be accurate. The present invention has been completed based on the finding that it is possible to predict (estimate) the starting performance on ice.

The present invention relates to a heavy-duty tire having a tread comprising an isoprene-based rubber and a butadiene rubber and having a rubber composition in which tan δ at −10 ° C. under the following shear mode conditions satisfies the following formula (1).
Tan δ ≤ 0.48 at 0.38 ≤ -10 ° C (1)
[Shear mode]
Stress: 0.5MPa
Frequency: 10Hz
Measurement temperature of tan δ: -10 ° C

The rubber composition preferably has a silica content of 14 parts by mass or more with respect to 100 parts by mass of the rubber component.

The rubber composition preferably contains a surface roughening material having an average particle diameter of 50 μm or more.

The rubber composition preferably contains carbon black having an average particle diameter of 20 nm or less and / or a cetyltrimethylammonium bromide adsorption specific surface area of 130 m ² / g or more.

The rubber composition preferably has a plasticizer content of 10 to 35 parts by mass with respect to 100 parts by mass of the rubber component.

The rubber composition preferably contains 5 to 20 parts by mass of the liquid plasticizer with respect to 100 parts by mass of the rubber component.

The rubber composition preferably has a resin content of 1.0 to 15 parts by mass with respect to 100 parts by mass of the rubber component.

According to the present invention, it is a heavy-duty tire having a tread containing an isoprene-based rubber and a butadiene rubber and having a tread made of a rubber composition having a tan δ at −10 ° C. under the shearing mode condition satisfying the above formula (1). , Can provide heavy-duty tires with excellent starting performance on ice.

The present invention is a heavy-duty tire having a tread comprising an isoprene-based rubber and a butadiene rubber, and having a rubber composition in which tan δ at −10 ° C. under the shearing mode condition satisfies the above formula (1). This makes it possible to impart excellent starting performance on ice.

The mechanism by which such an action is obtained is not clear, but it is inferred as follows.
As described above, the present invention clarifies the frequency at which the tread rubber is input from the icy road surface when starting on the icy road surface from the relationship between the icy road surface shape and the speed at the time of starting, and reflects the conditions in the viscoelasticity measurement conditions. As a result, the parameters of the above equation (1) were derived. Specifically, regarding the above equation (1), the viscoelasticity measurement is carried out at the temperature and frequency determined based on the principle of friction, and the measured stress is carried out using the contact pressure of the tire in the shear deformation mode. Hysteresis loss “-10 ° C. tan δ” is specified as the physical property parameter as the friction potential. By defining the optimum range of "-10 ° C tan δ", the potential of hysteresis loss friction (tan δ) is too high, so that the ice is melted on the ice road surface to generate water, and the contact area between the rubber and the road surface is reduced. It is thought that it is suppressed. Therefore, it is presumed that excellent on-ice starting performance can be imparted by satisfying the above equation (1).

As described above, the present invention is a heavy-duty tire having a tread containing an isoprene-based rubber and a butadiene rubber and having a rubber composition satisfying the formula (1) “tan δ ≦ 0.48 at 0.38 ≦ −10 ° C.”. By adopting the configuration of, the problem (purpose) of improving the starting performance on ice is solved. That is, the parameter of the above formula (1) does not define a problem (purpose), and the problem of the present application is improvement of starting performance on ice, and the invention is configured to satisfy the parameter as a solution for that purpose.

In the rubber composition (rubber composition after vulcanization) constituting the tread, tan δ at −10 ° C. under the following shear mode conditions satisfies the following formula (1). That is, the tan (-10 ° C.) in a state where a predetermined stress of 0.5 MPa is applied, not in a state where a predetermined strain is applied, satisfies the following formula (1).
Tan δ ≤ 0.48 at 0.38 ≤ -10 ° C (1)
[Shear mode]
Stress: 0.5MPa
Frequency: 10Hz
Measurement temperature of tan δ: -10 ° C

In the formula (1), the tan δ at −10 ° C. is preferably 0.39 or more, more preferably 0.40 or more, and even more preferably 0.41 or more. The tan δ at −10 ° C. is preferably 0.47 or less, more preferably 0.46 or less, still more preferably 0.45 or less. Within the above range, good starting performance on ice tends to be obtained.

The "tan δ at −10 ° C. under the shearing mode condition" can be measured by a viscoelasticity test, and specifically, it can be obtained by the method described in Examples described later.

For "tan δ at −10 ° C. under the shearing mode condition", the value of tan δ can be adjusted by using a method capable of adjusting tan δ at a low temperature. For example, a method of increasing the total amount of isoprene-based rubber and butadiene rubber, a method of increasing the amount of butadiene rubber, a method of increasing the amount of filler, a method of using a filler having a high surface surface, a method of blending an appropriate amount of resin, a liquid plasticizer (oil). , Liquid resin, etc.), and a method of blending a material that imparts a scratching friction effect on the ice road surface, such as eggshell powder, to obtain "tan δ at -10 ° C under the shear mode conditions". The value of tends to be large.

Then, by adjusting "tan δ at −10 ° C. under the shearing mode condition" by these methods, the formula (1) can be adjusted and a rubber composition satisfying this parameter can be produced.

(Rubber component)
As the rubber composition, isoprene-based rubber and butadiene rubber (BR) are used.

Examples of the isoprene-based rubber include natural rubber (NR), isoprene rubber (IR), modified NR, modified NR, modified IR and the like. As the NR, for example, SIR20, RSS # 3, TSR20 and the like, which are common in the rubber industry, can be used. The IR is not particularly limited, and for example, IR2200 or the like, which is common in the rubber industry, can be used. Modified NR includes deproteinized natural rubber (DPNR), high-purity natural rubber (UPNR), etc., and modified NR includes epoxidized natural rubber (ENR), hydrogenated natural rubber (HNR), grafted natural rubber, etc. Examples of the modified IR include epoxidized isoprene rubber, hydrogenated isoprene rubber, grafted isoprene rubber, and the like. These may be used alone or in combination of two or more.

In the rubber composition, the content of the isoprene-based rubber in 100% by mass of the rubber component is preferably 30% by mass or more, more preferably 40% by mass or more, still more preferably 50% by mass or more. The upper limit is preferably 90% by mass or less, more preferably 80% by mass or less, and further preferably 70% by mass or less. Within the above range, good starting performance on ice tends to be obtained.

The BR is not particularly limited, and for example, a high cis BR having a high cis content, a BR containing syndiotactic polybutadiene crystals, a BR synthesized using a rare earth catalyst, and the like can be used. These may be used alone or in combination of two or more. Among them, a high cis BR having a cis content of 90% by mass or more is preferable because the wear resistance is improved.

The BR may be a non-modified BR or a modified BR. The modified BR may be any BR having a functional group that interacts with a filler such as silica. For example, at least one end of the BR may be a compound (modifying agent) having the above functional group. Modified terminal-modified BR (terminal-modified BR having the above-mentioned functional group at the end), main-chain-modified BR having the above-mentioned functional group in the main chain, and main-chain end-modified BR having the above-mentioned functional group in the main chain and the end ( For example, it is modified with a polyfunctional compound having the above functional group in the main chain and at least one end modified with the above modifying agent (main chain terminal modified BR) or a polyfunctional compound having two or more epoxy groups in the molecule (cup). A terminal-modified BR or the like which has been ringed and introduced with a hydroxyl group or an epoxy group can be mentioned.

Examples of the functional group include an amino group, an amide group, a silyl group, an alkoxysilyl group, an isocyanate group, an imino group, an imidazole group, a urea group, an ether group, a carbonyl group, an oxycarbonyl group, a mercapto group, a sulfide group and a disulfide. Examples thereof include a group, a sulfonyl group, a sulfinyl group, a thiocarbonyl group, an ammonium group, an imide group, a hydrazo group, an azo group, a diazo group, a carboxyl group, a nitrile group, a pyridyl group, an alkoxy group, a hydroxyl group, an oxy group and an epoxy group. .. In addition, these functional groups may have a substituent. Among them, an amino group (preferably an amino group in which the hydrogen atom of the amino group is replaced with an alkyl group having 1 to 6 carbon atoms), an alkoxy group (preferably an alkoxy group having 1 to 6 carbon atoms), and an alkoxysilyl group (preferably an alkoxy group having 1 to 6 carbon atoms). An alkoxysilyl group having 1 to 6 carbon atoms) is preferable.

As the BR, for example, products such as Ube Industries, Ltd., JSR Corporation, Asahi Kasei Corporation, and Nippon Zeon Corporation can be used.

In the rubber composition, the content of BR in 100% by mass of the rubber component is preferably 5% by mass or more, more preferably 10% by mass or more, still more preferably 15% by mass or more. The upper limit is preferably 60% by mass or less, more preferably 50% by mass or less, still more preferably 40% by mass or less. Within the above range, good starting performance on ice tends to be obtained.

In the rubber composition, the total content of isoprene-based rubber and BR in 100% by mass of the rubber component is preferably 60% by mass or more, more preferably 80% by mass or more, still more preferably 90% by mass from the viewpoint of starting performance on ice. % Or more. The upper limit is not particularly limited and may be 100% by mass or less, but may be 90% by mass or less and 80% by mass or less.

In the rubber composition, as the rubber component that can be used in addition to the isoprene-based rubber and BR, for example, other diene-based rubber can be used. Examples of other diene-based rubbers include styrene butadiene rubber (SBR), styrene isoprene butadiene rubber (SIBR), ethylene propylene diene rubber (EPDM), chloroprene rubber (CR), and acrylonitrile butadiene rubber (NBR). Further, butyl rubber, fluororubber and the like can also be mentioned. Among them, SBR is preferable. The rubber components such as isoprene-based rubber, BR, and SBR may be used alone or in combination of two or more.

The SBR is not particularly limited, and for example, emulsion-polymerized styrene-butadiene rubber (E-SBR), solution-polymerized styrene-butadiene rubber (S-SBR) and the like can be used. These may be used alone or in combination of two or more.

The styrene content of SBR is preferably 5% by mass or more, more preferably 10% by mass or more, and further preferably 15% by mass or more. The styrene content is preferably 30% by mass or less, more preferably 25% by mass or less, still more preferably 20% by mass or less. Within the above range, good starting performance on ice tends to be obtained.
In the present specification, the styrene content ^{can be measured by 1 1} H-NMR measurement.

The vinyl bond amount of SBR is preferably 3% by mass or more, more preferably 5% by mass or more, and further preferably 7% by mass or more. The vinyl bond amount is preferably 25% by mass or less, more preferably 20% by mass or less, still more preferably 15% by mass or less. Within the above range, good starting performance on ice tends to be obtained.
In the present specification, the vinyl bond amount (1,2-bonded butadiene unit amount) can be measured by infrared absorption spectrum analysis.

As the SBR, for example, SBR manufactured and sold by Sumitomo Chemical Co., Ltd., JSR Corporation, Asahi Kasei Co., Ltd., Zeon Corporation, etc. can be used.

The SBR may be a non-modified SBR or a modified SBR. Examples of the modified SBR include a modified SBR into which a functional group similar to that of the modified BR has been introduced.

When the rubber composition contains SBR, the content of SBR in 100% by mass of the rubber component is preferably 5% by mass or more, more preferably 10% by mass or more, still more preferably 15% by mass or more. The upper limit is preferably 35% by mass or less, more preferably 30% by mass or less, still more preferably 25% by mass or less. Within the above range, good starting performance on ice tends to be obtained. Further, by using SBR, it is possible to increase the blending amount of silica, and there is a tendency that tan δ can be increased efficiently.

(Filler)
The rubber composition preferably contains a filler from the viewpoint of starting performance on ice. The filler is not particularly limited, and materials known in the rubber field can be used, and examples thereof include silica, carbon black, calcium carbonate, talc, alumina, clay, aluminum hydroxide, aluminum oxide, and mica. Of these, carbon black and silica are preferable.

In the rubber composition, the filler content (total content of filler) is preferably 20 parts by mass or more, more preferably 30 parts by mass or more, still more preferably 40 parts by mass or more with respect to 100 parts by mass of the rubber component. Particularly preferably, it is 45 parts by mass or more. The upper limit is preferably 150 parts by mass or less, more preferably 120 parts by mass or less, still more preferably 100 parts by mass or less, and particularly preferably 85 parts by mass or less. Within the above range, good starting performance on ice tends to be obtained.

The rubber composition contains carbon black (also referred to as carbon black (A)) having an average particle diameter of 20 nm or less and / or a cetyltrimethylammonium bromide adsorption specific surface area (CTAB) of 130 m ^{2 / g or more from the viewpoint of starting performance on ice.} Is preferable.

The average particle size of the carbon black (A) is preferably 20 nm or less, more preferably 17 nm or less, still more preferably 16 nm or less. The lower limit is not particularly limited, but is preferably 5 nm or more, more preferably 10 nm or more. Within the above range, good starting performance on ice tends to be obtained.
The average particle size of carbon black is a number average particle size, which is measured by a transmission electron microscope.

The CTAB of carbon black (A) is preferably 130 m ² / g or more, more preferably 140 m ² / g or more, still more preferably 145 m ² / g or more, and particularly preferably 150 m ² / g or more. The upper limit is not particularly limited, but is preferably 250 m ² / g or less, more preferably 200 m ² / g or less, and further preferably 180 m ² / g or less. Within the above range, good starting performance on ice tends to be obtained.
In addition, in this specification, the CTAB of carbon black is a value measured according to JIS K6217-3: 2001.

The nitrogen adsorption specific surface area (N ₂ SA) of the ^{carbon black (A) is preferably 125 m 2} / g or more, more preferably 145 m ² / g or more, ^{still more preferably 150 m 2} / g or more, and particularly preferably 155 m ² / g. That is all. The upper limit is not particularly limited, but is preferably 250 m ² / g or less, more preferably 200 m ² / g or less, and further preferably 180 m ² / g or less. Within the above range, good starting performance on ice tends to be obtained.
The carbon black N ₂ SA is obtained by JIS K 6217-2: 2001.

The iodine adsorption amount (IA) (mg / g) of the carbon black (A) is preferably 120 mg / g or more, more preferably 125 mg / g or more, still more preferably 130 mg / g or more, and particularly preferably 140 mg / g or more. be. The upper limit is not particularly limited, but is preferably 200 mg / g or less, more preferably 180 mg / g or less, still more preferably 160 mg / g or less. Within the above range, good starting performance on ice tends to be obtained.
In this specification, the iodine adsorption amount (IA) of carbon black is a value measured according to JIS K6217-1: 2001.

The ratio (CTAB / IA) of the adsorption specific surface area (CTAB) of cetyltrimethylammonium bromide to the iodine adsorption amount (IA) (mg / g) of carbon black (A) is preferably 0.85 m ² / mg or more, more preferably. Is 0.92 m ² / mg or more, more preferably 1.00 m ² / mg or more. The upper limit is not particularly limited, but is preferably 1.35 m ² / mg or less, more preferably 1.30 m ² / mg or less, and further preferably 1.25 m ² / mg or less. Within the above range, good starting performance on ice tends to be obtained.

Dibutyl phthalate absorption of the carbon black (A) (DBP) is preferably 120 cm ^3/100 g or more, more preferably 125 cm ^3/100 g or more, more preferably 135 cm ^3/100 g or more. The upper limit is not particularly limited, preferably 180cm ^3/100 g or less, more preferably 170cm ^3/100 g, more preferably not more than 160cm ³ / 100g. Within the above range, good starting performance on ice tends to be obtained.
The carbon black DBP is measured according to JIS K 6217-4: 2001.

Examples of the carbon black (A) include SAF. These carbon blacks may be used alone or in combination of two or more. Further, the carbon black (A) can also be produced by the production method described in JP-A-2000-3195353, JP-A-8-507555, and the like.

In the rubber composition, the content of carbon black (A) is preferably 10 parts by mass or more, more preferably 20 parts by mass or more, and further preferably 25 parts by mass or more with respect to 100 parts by mass of the rubber component. The content is preferably 80 parts by mass or less, more preferably 70 parts by mass or less, still more preferably 60 parts by mass or less, and particularly preferably 50 parts by mass or less. Within the above range, good starting performance on ice tends to be obtained.

The rubber composition may further contain carbon black (also referred to as carbon black (B)) other than the carbon black (A).

Examples of the carbon black (B) include carbon black having an average particle diameter of more than 20 nm and 25 nm or less and / or a cetyltrimethylammonium bromide adsorption specific surface area (CTAB) of 100 m ² / g or more and ^{less than 130 m 2} / g (carbon black (B)). Also referred to as) can be preferably used.

The average particle size of carbon black (B) is more than 20 nm and 25 nm or less (greater than 20 nm and 25 nm or less), but the lower limit is preferably 21 nm or more. The upper limit is preferably 24 nm or less, more preferably 23 nm or less. Within the above range, good starting performance on ice tends to be obtained.

The CTAB of carbon black (B) is preferably 105 m ² / g or more, more preferably 110 m ² / g or more. The upper limit is not particularly limited, but is preferably 125 m ² / g or less, and more preferably 120 m ² / g or less. Within the above range, good starting performance on ice tends to be obtained.

The average particle size and CTAB of carbon black (B) (other carbon black) can be measured by the same method as described above.

In the rubber composition, the content of carbon black (B) is preferably 5 parts by mass or more, more preferably 10 parts by mass or more, and further preferably 15 parts by mass or more with respect to 100 parts by mass of the rubber component. The content is preferably 50 parts by mass or less, more preferably 40 parts by mass or less, and further preferably 30 parts by mass or less. Within the above range, good starting performance on ice tends to be obtained.

The carbon black (B) (other carbon black) is not particularly limited, and examples thereof include N220, N234, N219, N339, N330, N326, N351, N550, and N762. For example, products such as Asahi Carbon Co., Ltd., Cabot Japan Co., Ltd., Tokai Carbon Co., Ltd., Mitsubishi Chemical Corporation, Lion Corporation, Shin Nikka Carbon Co., Ltd., Columbia Carbon Co., Ltd. can be used. These may be used alone or in combination of two or more. N220 is particularly preferable from the viewpoint of wear resistance and cost.

In the rubber composition, the content of carbon black (total content of carbon black (A) and carbon black (B)) is preferably 20 parts by mass or more, more preferably 30 parts by mass with respect to 100 parts by mass of the rubber component. More than parts, more preferably 35 parts by mass or more. The content is preferably 150 parts by mass or less, more preferably 100 parts by mass or less, still more preferably 80 parts by mass or less, and particularly preferably 70 parts by mass or less. Within the above range, good starting performance on ice tends to be obtained.

The content of carbon black (A) in 100% by mass of carbon black is preferably 40% by mass or more, more preferably 50% by mass or more, still more preferably 60% by mass or more, from the viewpoint of starting performance on ice. The upper limit of the content is not particularly limited and may be 100% by mass.

Examples of silica include dry silica (anhydrous silica) and wet silica (hydrous silica). Of these, wet silica is preferable because it has a large number of silanol groups. As commercially available products, products such as Degussa, Rhodia, Tosoh Silica Co., Ltd., Solvay Japan Co., Ltd., and Tokuyama Corporation can be used. These may be used alone or in combination of two or more.

In the rubber composition, the content of silica is preferably 5 parts by mass or more, more preferably 8 parts by mass or more, still more preferably 10 parts by mass or more, and particularly preferably 14 parts by mass or more with respect to 100 parts by mass of the rubber component. Is. The upper limit of the content is preferably 60 parts by mass or less, more preferably 50 parts by mass or less, and further preferably 40 parts by mass or less. Within the above range, good starting performance on ice tends to be obtained.

The nitrogen adsorption specific surface area (N ₂ SA) of silica is preferably 50 m ² / g or more, more preferably 100 m ² / g or more, and further preferably 150 m ² / g or more. The upper limit of N ₂ SA of silica is not particularly limited, but is preferably 350 m ² / g or less, more preferably 250 m ² / g or less, and further preferably 200 m ² / g or less. Within the above range, good starting performance on ice tends to be obtained.
The N ₂ SA of silica is a value measured by the BET method according to ASTM D3037-93.

(Silane coupling agent)
When the rubber composition contains silica, it is preferable to further contain a silane coupling agent.
The silane coupling agent is not particularly limited, and for example, bis (3-triethoxysilylpropyl) tetrasulfide, bis (2-triethoxysilylethyl) tetrasulfide, bis (4-triethoxysilylbutyl) tetrasulfide, and the like. Bis (3-trimethoxysilylpropyl) tetrasulfide, bis (2-trimethoxysilylethyl) tetrasulfide, bis (2-triethoxysilylethyl) trisulfide, bis (4-trimethoxysilylbutyl) trisulfide, bis ( 3-Triethoxysilylpropyl) disulfide, bis (2-triethoxysilylethyl) disulfide, bis (4-triethoxysilylbutyl) disulfide, bis (3-trimethoxysilylpropyl) disulfide, bis (2-trimethoxysilylethyl) ) Disulfide, bis (4-trimethoxysilylbutyl) disulfide, 3-trimethoxysilylpropyl-N, N-dimethylthiocarbamoyltetrasulfide, 2-triethoxysilylethyl-N, N-dimethylthiocarbamoyltetrasulfide, 3- Sulfide type such as triethoxysilylpropyl methacrylate monosulfide, 3-mercaptopropyltrimethoxysilane, 2-mercaptoethyltriethoxysilane, Mercapto type such as NXT and NXT-Z manufactured by Momentive, vinyl triethoxysilane, vinyl tri Vinyl-based such as methoxysilane, amino-based such as 3-aminopropyltriethoxysilane and 3-aminopropyltrimethoxysilane, glycidoxy such as γ-glycidoxypropyltriethoxysilane and γ-glycidoxypropyltrimethoxysilane. Examples thereof include nitro-based systems such as 3-nitropropyltrimethoxysilane and 3-nitropropyltriethoxysilane, and chloro-based systems such as 3-chloropropyltrimethoxysilane and 3-chloropropyltriethoxysilane. As commercially available products, products such as Degussa, Momentive, Shinetsu Silicone Co., Ltd., Tokyo Chemical Industry Co., Ltd., Azumax Co., Ltd., Toray Dow Corning Co., Ltd. can be used. These may be used alone or in combination of two or more.

In the rubber composition, the content of the silane coupling agent is preferably 3 parts by mass or more, and more preferably 6 parts by mass or more with respect to 100 parts by mass of silica. The content is preferably 20 parts by mass or less, more preferably 15 parts by mass or less. Within the above range, good starting performance on ice tends to be obtained.

(Surface roughening material)
The rubber composition may contain a surface roughening material. The surface roughening material is not particularly limited, and examples thereof include eggshell powder, short fibers, zinc oxide whiskers, shell powder, shirasu granules, crushed peach, volcanic ash, and iron fine particles. These may be used alone or in combination of two or more. Of these, eggshell powder is preferable. Eggshell flour is obtained by crushing eggshell, and its main component is calcium carbonate. When a surface roughening material such as eggshell powder is blended, the grip performance is improved by the scratching friction effect of the surface roughening material protruding from the tread surface, and the surface roughening material is formed by falling off from the tread surface. The edge effect (wiping effect) due to the holes made increases the contact area with the ice road surface and improves the grip performance, thereby improving the starting performance on ice.

The average particle size of the surface roughener (preferably eggshell powder) is preferably 50 μm or more, more preferably 70 μm or more, still more preferably 90 μm or more, and the upper limit is not particularly limited, but is preferably 250 μm or less, more preferably 250 μm or less. It is 200 μm or less, more preferably 150 μm or less, and particularly preferably 120 μm or less. Within the above range, good starting performance on ice tends to be obtained.
The average particle size of the surface roughening material (egg shell powder) is measured using a particle size distribution measuring device.

As the surface roughening material such as eggshell powder, for example, products such as Green Techno 21 Co., Ltd. and Kewpie Co., Ltd. can be used.

In the rubber composition, the content of the surface roughening material is preferably 0.5 parts by mass or more, more preferably 2 parts by mass or more, and further preferably 5 parts by mass or more with respect to 100 parts by mass of the rubber component. .. The upper limit is preferably 50 parts by mass or less, more preferably 30 parts by mass or less, and further preferably 20 parts by mass or less. Within the above range, good starting performance on ice tends to be obtained. The content of eggshell powder is preferably in the same range.

(Plasticizer)
A plasticizer may be added to the rubber composition. The plasticizer is a material that imparts plasticity to the rubber component, and examples thereof include liquid plasticizers (plasticizers in a liquid state at room temperature (25 ° C.)) and resins (resins in a solid state at room temperature (25 ° C.)). Can be mentioned.

When the rubber composition contains a plasticizer, the content (total amount of the plasticizer) is preferably 5 parts by mass or more, more preferably 10 parts by mass or more, still more preferably 15 parts by mass with respect to 100 parts by mass of the rubber component. It is more than a part. The upper limit is preferably 50 parts by mass or less, more preferably 40 parts by mass or less, still more preferably 35 parts by mass or less, and particularly preferably 30 parts by mass or less. Within the above range, good starting performance on ice tends to be obtained.

The liquid plasticizer (plasticizer in a liquid state at room temperature (25 ° C.)) is not particularly limited, and examples thereof include oils, liquid resins, liquid diene polymers, and liquid farnesene polymers. These may be used alone or in combination of two or more.

When the rubber composition contains a liquid plasticizer, the content thereof is preferably 3 parts by mass or more, more preferably 5 parts by mass or more, and further preferably 7 parts by mass or more with respect to 100 parts by mass of the rubber component. The upper limit is preferably 35 parts by mass or less, more preferably 25 parts by mass or less, still more preferably 20 parts by mass or less, and particularly preferably 15 parts by mass or less. Within the above range, good starting performance on ice tends to be obtained.

Examples of the oil include process oils, vegetable oils, or mixtures thereof. As the process oil, for example, a paraffin-based process oil, an aroma-based process oil, a naphthenic process oil, or the like can be used. Vegetable oils include castor oil, cottonseed oil, linseed oil, rapeseed oil, soybean oil, palm oil, palm oil, peanut oil, rosin, pine oil, pineapple, tall oil, corn oil, rice oil, beni flower oil, sesame oil, and olive oil. , Sunflower oil, palm kernel oil, camellia oil, jojoba oil, macadamia nut oil, tung oil and the like. Commercial products include Idemitsu Kosan Co., Ltd., Sankyo Yuka Kogyo Co., Ltd., Japan Energy Co., Ltd., Orisoi Co., Ltd., H & R Co., Ltd., Toyokuni Seiyu Co., Ltd., Showa Shell Sekiyu Co., Ltd., Fuji Kosan Co., Ltd., Products such as Nisshin Oillio Group Co., Ltd. can be used. Of these, process oils (paraffin-based process oils, aroma-based process oils, naphthen-based process oils, etc.) and vegetable oils are preferable.

When the rubber composition contains oil, the content thereof is preferably 0.5 parts by mass or more, more preferably 1.0 part by mass or more, still more preferably 1.5 parts by mass with respect to 100 parts by mass of the rubber component. That is all. The upper limit is preferably 35 parts by mass or less, more preferably 25 parts by mass or less, still more preferably 20 parts by mass or less, and particularly preferably 15 parts by mass or less. Within the above range, good starting performance on ice tends to be obtained.

Examples of the liquid resin include terpene-based resin (including terpenephenol resin and aromatic-modified terpene resin), rosin resin, styrene-based resin, C5-based resin, C9-based resin, C5 / C9-based resin, and di, which are in a liquid state at 25 ° C. Cyclopentadiene (DCPD) resin, Kumaron inden resin (including Kumaron and Inden simple resin), phenol resin, olefin resin, polyurethane resin, acrylic resin and the like can be mentioned.

When the rubber composition contains a liquid resin, the content thereof is preferably 0.5 parts by mass or more, more preferably 1.0 part by mass or more, still more preferably 1.5 parts by mass with respect to 100 parts by mass of the rubber component. It is more than a part. The upper limit is preferably 35 parts by mass or less, more preferably 25 parts by mass or less, still more preferably 20 parts by mass or less, and particularly preferably 15 parts by mass or less. Within the above range, good starting performance on ice tends to be obtained.

Examples of the liquid diene polymer include a liquid styrene butadiene copolymer (liquid SBR), a liquid butadiene polymer (liquid BR), a liquid isoprene polymer (liquid IR), and a liquid styrene isoprene copolymer (liquid) in a liquid state at 25 ° C. SIR), liquid styrene butadiene styrene block copolymer (liquid SBS block polymer), liquid styrene isoprene styrene block copolymer (liquid SIS block polymer), liquid farnesene polymer, liquid farnesene butadiene copolymer and the like. .. These may have the terminal or main chain denatured with a polar group.

When the rubber composition contains a liquid diene polymer, the content thereof is preferably 0.5 parts by mass or more, more preferably 1.0 part by mass or more, still more preferably 1. It is 5 parts by mass or more. The upper limit is preferably 35 parts by mass or less, more preferably 25 parts by mass or less, still more preferably 20 parts by mass or less, and particularly preferably 15 parts by mass or less. Within the above range, good starting performance on ice tends to be obtained.

The liquid farnesene-based polymer is a polymer obtained by polymerizing farnesene, and has a structural unit based on farnesene. Farnesene includes α-farnesene ((3E, 7E) -3,7,11-trimethyl-1,3,6,10-dodecatetraene) and β-farnesene (7,11-dimethyl-3-methylene-1). , 6,10-Dodecatorien) and the like, but (E) -β-farnesene having the following structure is preferable.

The liquid farnesene-based polymer may be a homopolymer of farnesene (farnesene homopolymer) or a copolymer of farnesene and a vinyl monomer (farnesene-vinyl monomer copolymer).

Examples of vinyl monomers include styrene, 2-methylstyrene, 3-methylstyrene, 4-methylstyrene, α-methylstyrene, 2,4-dimethylstyrene, 2,4-diisopropylstyrene, 4-tert-butylstyrene, 5-. t-Butyl-2-methylstyrene, vinylethylbenzene, divinylbenzene, trivinylbenzene, divinylnaphthalene, tert-butoxystyrene, vinylbenzyldimethylamine, (4-vinylbenzyl) dimethylaminoethyl ether, N, N-dimethylaminoethyl Styrene, N, N-dimethylaminomethyl styrene, 2-ethyl styrene, 3-ethyl styrene, 4-ethyl styrene, 2-t-butyl styrene, 3-t-butyl styrene, 4-t-butyl styrene, vinyl xylene, Examples thereof include aromatic vinyl compounds such as vinylnaphthalene, vinyltoluene, vinylpyridine, diphenylethylene, tertiary amino group-containing diphenylethylene, and conjugated diene compounds such as butadiene and isoprene. These may be used alone or in combination of two or more. Of these, butadiene is preferable. That is, as the farnesene-vinyl monomer copolymer, a copolymer of farnesene and butadiene (farnesene-butadiene copolymer) is preferable.

In the farnesene-vinyl monomer copolymer, the mass-based copolymerization ratio (farnesene / vinyl monomer) of farnesene and the vinyl monomer is preferably 40/60 to 90/10.

As the liquid farnesene-based polymer, one having a weight average molecular weight (Mw) of 3,000 to 300,000 can be preferably used. The Mw of the liquid farnesene polymer is preferably 8,000 or more, more preferably 10,000 or more, and preferably 100,000 or less, more preferably 60,000 or less, still more preferably 50,000 or less.

When the rubber composition contains a liquid farnesene polymer, the content thereof is preferably 1 part by mass or more, more preferably 3 parts by mass or more, still more preferably 5 parts by mass or more with respect to 100 parts by mass of the rubber component. .. The upper limit is preferably 35 parts by mass or less, more preferably 25 parts by mass or less, still more preferably 20 parts by mass or less, and particularly preferably 15 parts by mass or less. Within the above range, good starting performance on ice tends to be obtained.

Examples of the resin (resin in a solid state at room temperature (25 ° C)) include an aromatic vinyl polymer, a kumaron inden resin, a kumaron resin, an inden resin, a phenol resin, and a rosin resin in a solid state at room temperature (25 ° C). , Petroleum resin, terpene resin, acrylic resin and the like. Further, the resin may be hydrogenated. These may be used alone or in combination of two or more. Of these, terpene-based resins are preferable from the viewpoint of starting performance on ice.

In the rubber composition, the content of the resin with respect to 100 parts by mass of the rubber component is preferably 1 part by mass or more, more preferably 3 parts by mass or more, still more preferably 5 parts by mass or more. The upper limit is preferably 30 parts by mass or less, more preferably 20 parts by mass or less, and further preferably 15 parts by mass or less. Within the above range, good starting performance on ice tends to be obtained.

The softening point of the resin is preferably 80 ° C. or higher, more preferably 90 ° C. or higher, and even more preferably 100 ° C. or higher. The upper limit is preferably 180 ° C. or lower, more preferably 160 ° C. or lower, and even more preferably 140 ° C. or lower. Within the above range, good starting performance on ice tends to be obtained.
The softening point of the resin is the temperature at which the ball drops when the softening point defined in JIS K6220-1: 2001 is measured by a ring-shaped softening point measuring device.

The terpene-based resin is a polymer containing terpene as a constituent unit. For example, a polyterpene resin obtained by polymerizing a terpene compound, an aromatic-modified terpene resin obtained by polymerizing a terpene compound and an aromatic compound, and the like can be mentioned. In addition, these hydrogenated additives can also be used.

The polyterpene resin is a resin obtained by polymerizing a terpene compound. The terpene compound is _{a hydrocarbon having a composition of (C 5} H ₈ ) _n and an oxygen-containing derivative thereof, and is a mono terpene (C ₁₀ H ₁₆ ), a sesqui terpene (C ₁₅ H ₂₄ ), and a diterpene (C ₂₀ H). It is a compound having a terpene as a basic skeleton classified into _{32) and the like.} Examples thereof include terpinene, 1,8-cineol, 1,4-cineol, α-terpineol, β-terpineol, γ-terpineol and the like.

Examples of the polyterpene resin include pinene resin, limonene resin, dipentene resin, pinene / limonene resin and the like made from the above-mentioned terpene compound. Of these, pinene resin is preferable. The pinene resin usually contains both α-pinene and β-pinene having an isomer relationship, but due to the difference in the contained components, β-pinene resin containing β-pinene as a main component and α- It is classified as α-pinene resin containing pinene as the main component.

Examples of the aromatic-modified terpene resin include terpene phenol resins made from the terpene compounds and phenolic compounds, and terpene styrene resins made from the terpene compounds and styrene compounds. Further, a terpene phenol styrene resin made from the above-mentioned terpene compound, phenol-based compound and styrene-based compound can also be used. Examples of the phenolic compound include phenol, bisphenol A, cresol, xylenol and the like. Moreover, styrene, α-methylstyrene and the like can be mentioned as a styrene compound.

In the rubber composition, the content of the terpene resin with respect to 100 parts by mass of the rubber component is preferably 1 part by mass or more, more preferably 3 parts by mass or more, and further preferably 5 parts by mass or more. The upper limit is preferably 30 parts by mass or less, more preferably 20 parts by mass or less, and further preferably 15 parts by mass or less. Within the above range, good starting performance on ice tends to be obtained.

The aromatic vinyl polymer is a polymer containing an aromatic vinyl monomer as a constituent unit. For example, a resin obtained by polymerizing α-methylstyrene and / or styrene can be mentioned, and specific examples thereof include a homopolymer of styrene (styrene resin) and a homopolymer of α-methylstyrene (α-methylstyrene resin). ), Polymers of α-methylstyrene and styrene, copolymers of styrene and other monomers, and the like. In the rubber composition, the content of the aromatic vinyl polymer with respect to 100 parts by mass of the rubber component is preferably 1 to 30 parts by mass.

The kumaron indene resin is a resin containing kumaron and indene as main monomer components constituting the skeleton (main chain) of the resin. Examples of the monomer component contained in the skeleton other than kumaron and indene include styrene, α-methylstyrene, methylindene, vinyltoluene and the like. In the rubber composition, the content of the kumaron indene resin with respect to 100 parts by mass of the rubber component is preferably 1 to 30 parts by mass.

The kumaron resin is a resin containing kumaron as a main monomer component constituting the skeleton (main chain) of the resin. In the rubber composition, the content of the kumaron resin with respect to 100 parts by mass of the rubber component is preferably 1 to 30 parts by mass.

The indene resin is a resin containing indene as a main monomer component constituting the skeleton (main chain) of the resin. In the rubber composition, the content of the indene resin with respect to 100 parts by mass of the rubber component is preferably 1 to 30 parts by mass.

As the phenol resin, for example, a known polymer such as a polymer obtained by reacting phenol with aldehydes such as formaldehyde, acetaldehyde, and furfural with an acid or alkali catalyst can be used. Among them, those obtained by reacting with an acid catalyst (novolak type phenol resin or the like) are preferable. In the rubber composition, the content of the phenol resin with respect to 100 parts by mass of the rubber component is preferably 1 to 30 parts by mass.

Examples of the rosin resin include natural rosins, polymerized rosins, modified rosins, ester compounds thereof, and rosin-based resins typified by hydrogen additives thereof. In the rubber composition, the content of the rosin resin with respect to 100 parts by mass of the rubber component is preferably 1 to 30 parts by mass.

Examples of the petroleum resin include C5 resin, C9 resin, C5 / C9 resin, dicyclopentadiene (DCPD) resin and the like. Of these, DCPD resin is preferable. In the rubber composition, the content of the petroleum resin with respect to 100 parts by mass of the rubber component is preferably 1 to 30 parts by mass.

The acrylic resin is a polymer containing an acrylic monomer as a constituent unit. For example, a styrene acrylic resin such as a styrene acrylic resin having a carboxyl group and obtained by copolymerizing an aromatic vinyl monomer component and an acrylic monomer component can be mentioned. Among them, a solvent-free carboxyl group-containing styrene-acrylic resin can be preferably used.

The solvent-free carboxyl group-containing styrene acrylic resin is a high-temperature continuous polymerization method (high-temperature continuous lump polymerization method) (US patent) without using polymerization initiators, chain transfer agents, organic solvents, etc. as auxiliary raw materials as much as possible. 4,414,370, JP-A-59-6207, JP-A-5-58805, JP-A 1-313522, US Pat. No. 5,010,166, Toa Synthetic Research It is a (meth) acrylic resin (polymer) synthesized by the method described in the annual report TREND2000 No. 3, p42-45 and the like. In addition, in this specification, (meth) acrylic means methacryl and acrylic.

Examples of the acrylic monomer component constituting the acrylic resin include (meth) acrylic acid, (meth) acrylic acid ester (alkyl ester such as 2-ethylhexyl acrylate, aryl ester, aralkyl ester, etc.), and (meth) acrylamide. , (Meta) acrylic acid derivatives such as (meth) acrylamide derivatives. In addition, (meth) acrylic acid is a general term for acrylic acid and methacrylic acid.

Examples of the aromatic vinyl monomer component constituting the acrylic resin include aromatic vinyls such as styrene, α-methylstyrene, vinyltoluene, vinylnaphthalene, divinylbenzene, trivinylbenzene, and divinylnaphthalene.

Further, as the monomer component constituting the acrylic resin, other monomer components may be used together with (meth) acrylic acid, a (meth) acrylic acid derivative, and aromatic vinyl. In the rubber composition, the content of the acrylic resin with respect to 100 parts by mass of the rubber component is preferably 1 to 30 parts by mass.

Examples of the plasticizer include Maruzen Petrochemical Co., Ltd., Sumitomo Bakelite Co., Ltd., Yasuhara Chemical Co., Ltd., Toso Co., Ltd., Rutgers Chemicals Co., Ltd., BASF Co., Ltd., Arizona Chemical Co., Ltd., Nikko Chemical Co., Ltd., ( Products such as Nippon Catalyst Co., Ltd., JXTG Energy Co., Ltd., Arakawa Chemical Industry Co., Ltd., and Taoka Chemical Industry Co., Ltd. can be used.

(Other materials)
The rubber composition preferably contains an antiaging agent from the viewpoint of crack resistance, ozone resistance and the like.

The antiaging agent is not particularly limited, but is a naphthylamine-based antiaging agent such as phenyl-α-naphthylamine; a diphenylamine-based antiaging agent such as octylated diphenylamine and 4,4'-bis (α, α'-dimethylbenzyl) diphenylamine. N-isopropyl-N'-phenyl-p-phenylenediamine, N- (1,3-dimethylbutyl) -N'-phenyl-p-phenylenediamine, N, N'-di-2-naphthyl-p-phenylene P-phenylenediamine-based antioxidants such as diamine; quinoline-based antioxidants such as polymers of 2,2,4-trimethyl-1,2-dihydroquinolin; 2,6-di-t-butyl-4-methyl Monophenolic anti-aging agents such as phenol and styrenated phenol; tetrakis- [methylene-3- (3', 5'-di-t-butyl-4'-hydroxyphenyl) propionate] bis, tris, polyphenols such as methane Examples include anti-aging agents. Of these, p-phenylenediamine-based antioxidants and quinoline-based antioxidants are preferable, and N- (1,3-dimethylbutyl) -N'-phenyl-p-phenylenediamine and 2,2,4-trimethyl-1 are preferable. , 2-Dihydroquinoline polymers are more preferred. As commercially available products, for example, products of Seiko Chemical Co., Ltd., Sumitomo Chemical Co., Ltd., Ouchi Shinko Chemical Industry Co., Ltd., Flexis Co., Ltd. and the like can be used.

In the rubber composition, the content of the antiaging agent is preferably 0.2 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. The content is preferably 7.0 parts by mass or less, more preferably 4.0 parts by mass or less.

The rubber composition preferably contains stearic acid. In the rubber composition, the content of stearic acid is preferably 0.5 to 10 parts by mass, more preferably 0.5 to 5 parts by mass with respect to 100 parts by mass of the rubber component.

As the stearic acid, conventionally known ones can be used, for example, products such as NOF Corporation, NOF Corporation, Kao Corporation, Wako Pure Chemical Industries, Ltd., and Chiba Fatty Acid Co., Ltd. are used. can.

The rubber composition preferably contains zinc oxide. In the rubber composition, the content of zinc oxide is preferably 0.5 to 10 parts by mass, and more preferably 1 to 5 parts by mass with respect to 100 parts by mass of the rubber component.

As the zinc oxide, conventionally known zinc oxide can be used, for example, Mitsui Metal Mining Co., Ltd., Toho Zinc Co., Ltd., Hakusui Tech Co., Ltd., Shodo Chemical Industry Co., Ltd., Sakai Chemical Industry Co., Ltd., etc. Products can be used.

Wax may be added to the rubber composition. In the rubber composition, the content of the wax is preferably 0.5 to 10 parts by mass, and more preferably 1 to 5 parts by mass with respect to 100 parts by mass of the rubber component.

The wax is not particularly limited, and examples thereof include petroleum wax, natural wax, and synthetic wax obtained by purifying or chemically treating a plurality of waxes. These waxes may be used alone or in combination of two or more.

Examples of petroleum-based waxes include paraffin wax and microcrystalline wax. The natural wax is not particularly limited as long as it is a wax derived from non-petroleum resources, and is, for example, a plant wax such as candelilla wax, carnauba wax, wood wax, rice wax, jojoba wax; Animal waxes; mineral waxes such as ozokelite, selecin, petrolactam; and purified products thereof. As commercially available products, for example, products such as Ouchi Shinko Kagaku Kogyo Co., Ltd., Nippon Seiro Co., Ltd., and Seiko Kagaku Co., Ltd. can be used.

It is preferable to add sulfur to the rubber composition from the viewpoint of forming an appropriate crosslinked chain on the polymer chain and imparting good performance.

In the rubber composition, the sulfur content is preferably 0.1 part by mass or more, more preferably 0.3 part by mass or more, still more preferably 0.5 part by mass or more with respect to 100 parts by mass of the rubber component. .. The content is preferably 4.0 parts by mass or less, more preferably 3.0 parts by mass or less, and further preferably 2.0 parts by mass or less.

Examples of sulfur include powdered sulfur, precipitated sulfur, colloidal sulfur, insoluble sulfur, highly dispersible sulfur, and soluble sulfur commonly used in the rubber industry. As commercial products, products such as Tsurumi Chemical Industry Co., Ltd., Karuizawa Sulfur Co., Ltd., Shikoku Kasei Industry Co., Ltd., Flexis Co., Ltd., Nippon Inui Kogyo Co., Ltd., Hosoi Chemical Industry Co., Ltd., etc. can be used. These may be used alone or in combination of two or more.

The rubber composition preferably contains a vulcanization accelerator.
In the rubber composition, the content of the vulcanization accelerator is not particularly limited and may be freely determined according to the desired vulcanization rate and crosslinking density, but is preferably 2. It is 0 parts by mass or more, more preferably 3.0 parts by mass or more, and further preferably 3.5 parts by mass or more. The upper limit is preferably 8.0 parts by mass or less, more preferably 6.0 parts by mass or less, and further preferably 5.0 parts by mass or less.

The type of vulcanization accelerator is not particularly limited, and a commonly used one can be used. Examples of the vulcanization accelerator include thiazole-based vulcanization accelerators such as 2-mercaptobenzothiazole, di-2-benzothiazolyl disulfide, and N-cyclohexyl-2-benzothiadylsulfenamide; tetramethylthiuram disulfide (TMTD). ), Tetrabenzylthiuram disulfide (TBzTD), tetrakis (2-ethylhexyl) thiuram disulfide (TOT-N) and other thiuram-based vulcanization accelerators; N-cyclohexyl-2-benzothiazolesulfenamide, N-t-butyl- 2-benzothiazolyl sulfenamide, N-oxyethylene-2-benzothiazolesulfenamide, N-oxyethylene-2-benzothiazolesulfenamide, N, N'-diisopropyl-2-benzothiazolesulfenamide, etc. Sulfenamide-based vulcanization accelerator; guanidine-based vulcanization accelerators such as diphenylguanidine, dioltotrilguanidine, orthotrilviguanidine can be mentioned. These may be used alone or in combination of two or more. Of these, sulfenamide-based, guanidine-based, and benzothiazole-based vulcanization accelerators are preferable.

In addition to the above components, a compounding agent generally used in the tire industry, for example, a material such as a mold release agent may be appropriately added to the rubber composition.

As a method for producing the rubber composition, a known method can be used. For example, each of the above components can be kneaded using a rubber kneading device such as an open roll or a Banbury mixer, and then vulcanized.

As the kneading conditions, in the base kneading step of kneading additives other than the vulcanizing agent and the vulcanization accelerator, the kneading temperature is usually 50 to 200 ° C., preferably 80 to 190 ° C., and the kneading time is usually 30. Seconds to 30 minutes, preferably 1 minute to 30 minutes. In the finish kneading step of kneading the vulcanizing agent and the vulcanization accelerator, the kneading temperature is usually 100 ° C. or lower, preferably room temperature to 80 ° C. Further, the composition in which the vulcanizing agent and the vulcanization accelerator are kneaded is usually subjected to a vulcanization treatment such as press vulcanization. The vulcanization temperature is usually 120 to 200 ° C, preferably 140 to 180 ° C.

The rubber composition is used for a tread (cap tread), and the tread (cap tread) may be at least partially composed of the above rubber composition, and may be entirely composed of the above rubber composition. You may.

Heavy-duty tires are manufactured by conventional methods using rubber compositions. That is, the rubber composition containing various additives as needed is extruded according to the shape of the tread (cap tread) at the unvulcanized stage, and molded by a normal method on a tire molding machine. After forming an unvulcanized tire by laminating it together with other tire members, it can be heated and pressed in a vulcanizer to manufacture a heavy load tire.

The heavy-duty tire in the present specification is a tire having particularly excellent durability, and examples thereof include tires for trucks and buses, industrial tires used for industrial vehicles such as heavy machinery, and the like. For heavy-duty tires, all-steel tires are usually used in which the cords used for the case and the breaker are both steel cords.

Since the heavy load tire has good starting performance on ice, it can be suitably used as a heavy load tire for winter (studless tire for heavy load, snow tire for heavy load, stud tire for heavy load, etc.).

The present invention will be specifically described with reference to Examples, but the present invention is not limited thereto.

(Manufacturing example)
A combustion zone with an inner diameter of 800 mm and a length of 1600 mm equipped with an air introduction duct and a combustion burner, a raw material introduction band consisting of a narrow diameter portion with an inner diameter of 145 mm and a length of 1000 mm connected from the combustion zone and connected through a raw material nozzle from the periphery, quench. Using a carbon black reactor equipped with an inner diameter of 400 mm and a length of 3000 mm in which a rear reaction zone is sequentially joined, heavy fuel oil C is used as fuel and creosort oil is used as the raw material hydrocarbon, and carbon black is set under each condition. A was manufactured.

Various chemicals used in Examples and Comparative Examples will be collectively described.
NR: TSR20
BR: BR360 manufactured by Ube Industries, Ltd. (cis 1,4 bond amount 98% by mass)
SBR: Toughden 1000 manufactured by Asahi Kasei Corporation (non-modified S-SBR, styrene content 18% by mass, vinyl bond amount 10% by mass)
Carbon black B: N220 (average particle diameter _{^{22nm, CTAB115m 2 / g, N}} 2 SA115m 2 /g,IA118mg/g,CTAB/IA0.97,DBP113cm 3 / 100g)
Carbon black A: Preparation (average particle diameter _{^{16nm, CTAB158m 2 / g, N}} 2 SA170m 2 /g,IA145mg/g,CTAB/IA1.09,DBP138cm 3 / 100g)
Silica: Evonik Degussa Uratosyl VN3 (N ₂ SA172m ² / g)
Eggshell powder 1: Egg calcium manufactured by Kewpie Co., Ltd. (Calhope, average particle size 10 μm)
Eggshell powder 2: Egg calcium manufactured by Kewpie Co., Ltd. (Calhope, average particle size 50 μm)
Eggshell powder 3: Eggshell powder made by Green Techno 21 Co., Ltd. (average particle size 100 μm)
Oil: Diana Process NH-70S (aroma process oil) manufactured by Idemitsu Kosan Co., Ltd.
Resin: YS resin PX1150N manufactured by Yasuhara Chemical Co., Ltd. (β-pinene resin, softening point 115 ° C)
Liquid farnesene polymer: L-FBR-742 manufactured by Kuraray (liquid farnesene butadiene copolymer, SP value 8.1)
Silane coupling agent: Si266 (bis (3-triethoxysilylpropyl) disulfide) manufactured by Evonik Degussa.
Wax: Ozo Ace 0355 manufactured by Nippon Seiro Co., Ltd.
Anti-aging agent 6C: Nocrack 6C (N-phenyl-N'-(1,3-dimethylbutyl) -p-phenylenediamine) manufactured by Ouchi Shinko Kagaku Kogyo Co., Ltd.
Stearic acid: Zinc oxide manufactured by NOF Corporation: Zinc oxide type 2 sulfur manufactured by Mitsui Metal Mining Co., Ltd .: HK-200-5 (powdered sulfur containing 5% by mass oil) manufactured by Hosoi Chemical Industry Co., Ltd.
Vulcanization accelerator CZ: Noxeller CZ (N-cyclohexyl-2-benzothiazolylsulfenamide) manufactured by Ouchi Shinko Kagaku Kogyo Co., Ltd.
Vulcanization accelerator DPG: Noxeller D (N, N'-diphenylguanidine) manufactured by Ouchi Shinko Kagaku Kogyo Co., Ltd.

[Examples and Comparative Examples]
According to the formulation shown in Table 1, using a 1.7L Banbury mixer manufactured by Kobe Steel, Ltd., chemicals other than sulfur and vulcanization accelerator are kneaded under the condition of 150 ° C for 5 minutes, and the kneaded product is kneaded. Got Next, sulfur and a vulcanization accelerator were added to the obtained kneaded product, and the mixture was kneaded under the condition of 80 ° C. for 5 minutes using an open roll to obtain an unvulcanized rubber composition.
The obtained unvulcanized rubber composition is molded into the shape of a cap tread and bonded together with other tire members to prepare an unvulcanized tire, which is press-vulcanized for 10 minutes under the condition of 170 ° C. for a test tire. (Winter heavy load tire, size: 11R22.5) was obtained.

The rubber physical characteristics and tire performance of the produced test tires were evaluated by the following methods. The results are shown in Table 1. The reference comparison example in Table 1 is Comparative Example 1.

<Viscoelasticity test>
A sample (rubber composition after vulcanization) taken from the cap tread of a test tire was subjected to loss tangent (loss tangent) under the following shear deformation mode conditions using a viscoelasticity tester (DMA + 450) manufactured by Metarivib. Tanδ) at −10 ° C. was measured.
[Shear mode]
Stress: 0.5MPa
Frequency: 10Hz
Measurement temperature of tan δ: -10 ° C
Sample size: diameter 10 mm, thickness 2 mm

(Starting performance on ice)
Test tires are attached to all wheels of an actual vehicle (a large truck with a gross vehicle weight of 20 tons, two passengers), and with the air pressure specified by the vehicle and 50% of the maximum load capacity loaded, 10 km / from a stationary state on an icy road surface. The acceleration distance was measured until it reached h, and the index was displayed by the following formula. The larger the index, the better the driving performance (starting performance on ice) on the road surface on ice.
(Starting performance index on ice) = (acceleration distance of standard comparative example) / (acceleration distance of each formulation) x 100

From Table 1, the heavy-duty tires of the examples using the rubber composition containing isoprene-based rubber and butadiene rubber and having tan δ at −10 ° C. under the shear mode condition satisfying the above formula (1) are started on ice. It was excellent in performance.

Claims (7)

Contains isoprene-based rubber and butadiene rubber,
A heavy-duty tire having a tread made of a rubber composition in which tan δ at −10 ° C. under the following shear mode conditions satisfies the following formula (1).
Tan δ ≤ 0.48 at 0.38 ≤ -10 ° C (1)
[Shear mode]
Stress: 0.5MPa
Frequency: 10Hz
Measurement temperature of tan δ: -10 ° C The heavy-duty tire according to claim 1, wherein the rubber composition has a silica content of 14 parts by mass or more with respect to 100 parts by mass of the rubber component. The heavy-duty tire according to claim 1 or 2, wherein the rubber composition contains a surface roughening material having an average particle diameter of 50 μm or more. The heavy-duty tire according to any one of claims 1 to 3, wherein the rubber composition comprises carbon black having an average particle diameter of 20 nm or less and / or a cetyltrimethylammonium bromide adsorption specific surface area of 130 m ^{2 / g or more.} The heavy-duty tire according to any one of claims 1 to 4, wherein the rubber composition has a plasticizer content of 10 to 35 parts by mass with respect to 100 parts by mass of the rubber component. The heavy-duty tire according to any one of claims 1 to 5, wherein the rubber composition has a content of a liquid plasticizer of 5 to 20 parts by mass with respect to 100 parts by mass of a rubber component. The heavy-duty tire according to any one of claims 1 to 6, wherein the rubber composition has a resin content of 1.0 to 15 parts by mass with respect to 100 parts by mass of the rubber component.