JP2001253974A - Pneumatic tire for high-speed running and heavy-duty use - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide the subject pneumatic tire causing no chippings, and excellent in durability and abrasion resistance. SOLUTION: This pneumatic tire for high-speed running and heavy-duty use is such a tire having a tread made from a rubber composition comprising 100 pts.wt. of a rubber component composed of 0-40 wt.% of a butadiene rubber >=4.2×105 in weight-average molecular weight(Mw), >=2.0 in the ratio Mw/Mn (number-average molecular weight) and 95% in cis-type content and 60-100 wt.% of an isoprene-based rubber, 40-55 pts.wt. of carbon black 140-160 m2/g in nitrogen adsorption specific surface area (N2SA), 130-160 mL/100 g in dibutyl phthalate(DBP) oil absorption and 1,500-2,500 ppm in hydrogen generation amount, and a total of 2.5-3.0 pts.wt. of a sulfenamide-based vulcanization promoter and sulfur so as to be 0.35-1.3 in the weight ratio (sulfenamide-based vulcanization promoter/sulfur).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high-speed and high-load pneumatic tire, and more particularly, to a pneumatic tire which is free from chipping (lack of rubber at a rib end), has excellent durability and abrasion resistance, and is used for aircraft. The present invention relates to a pneumatic tire for high speed and high load, which is particularly suitable as

[0002]

2. Description of the Related Art High-speed, high-load pneumatic tires, particularly pneumatic tires for aircraft, have the following concerns or problems. That is, at the time of overload takeoff and landing at the time of abnormality, due to the large strain and load applied to the tread rubber, the calorific value of the tread rubber becomes extremely large,
There is a fear of adhesion peeling failure between the front and rear surfaces. Further, in a normal state, there is a concern of chipping (lack of rubber at a rib end) due to large deformation at the time of a tight turn or the like during Taxi running. In addition, during landing, severe slip,
There are problems such as slippage of the tread rubber on the runway surface for a long time from the start of landing, and early wear of the tread rubber due to scratching. Without these concerns or problems, there is no chipping (rubber chipping at the end of the rib),
At present, high-speed, high-load pneumatic tires having excellent durability and abrasion resistance and suitable for aircraft and the like have not yet been provided.

[0003]

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned conventional concerns or problems and to achieve the following objects. That is, an object of the present invention is to provide a high-speed, high-load pneumatic tire that is free from chipping (rubber chipping at a rib end), has excellent durability and abrasion resistance, and is particularly suitable for aircraft and the like. I do.

[0004]

Means for solving the above problems are as follows. <1> the weight average molecular weight is 4.2 × 10 ⁵ or more;
0 to 40% by weight of butadiene rubber having a ratio of weight average molecular weight to number average molecular weight (weight average molecular weight / number average molecular weight) of 2.0 or more and a cis content of 95%, and isoprene rubber 60 Rubber component 1 containing -100% by weight
00 parts by weight and a nitrogen adsorption specific surface area (N ₂ SA) of 140
160 m ² / g, and dibutyl phthalate (DB
P) 40 to 55 parts by weight of carbon black having an oil absorption of 130 to 160 ml / 100 g and an amount of generated hydrogen of 1500 to 2500 ppm, and a weight ratio (sulfenamide compound / sulfur) of 0.35 to 1.3. So that the total amount of the sulfenamide compound and sulfur is 2.5 to 3.
A high-speed, high-load pneumatic tire comprising a tread formed of a rubber composition containing 0 parts by weight. <2> The pneumatic tire for high speed and high load according to <1>, which is a pneumatic tire for aircraft.

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION The high-speed, high-load pneumatic tire of the present invention has at least a tread, and is not particularly limited as long as the tread is formed of the following rubber composition, and there is no particular limitation. The configuration of a pneumatic tire for high load (for example, the configuration of a tubeless tire) can be adopted, and the shape, structure, size, and the like can be appropriately selected according to the purpose.

[0006] The rubber composition contains a rubber component, carbon black, a sulfenamide compound, and sulfur, and further contains other components appropriately selected as necessary.

-Rubber component- The rubber component contains 0 to 40% by weight of butadiene rubber and 60 to 100% by weight of isoprene-based rubber, preferably 10 to 30% by weight of butadiene rubber and 90 to 70% of isoprene rubber. % By weight. If the rubber component contains the butadiene rubber in an amount exceeding 40% by weight, it is not preferable since cut damage cannot be avoided and the chipping (rubber chipping at a rib end) occurs. Incidentally, when the rubber component contains the butadiene rubber,
This is advantageous in terms of wear resistance.

The butadiene rubber has a weight average molecular weight (M
It is necessary that w) is 4.2 × 10 ⁵ or more, preferably 4.5 × 10 ⁵ or more. If the weight average molecular weight is less than 4.2 × 10 ⁵ , the abrasion resistance of the tread rubber is not good, which is not preferable.

The butadiene rubber has a weight average molecular weight (M
The ratio (weight average molecular weight (Mw) / number average molecular weight (Mn)) of w) to the number average molecular weight (Mn) needs to be 2.0 or more, and preferably 2.1 or more.
The ratio (weight average molecular weight (Mw) / number average molecular weight (M
If n)) is less than 2.0, the abrasion resistance of the tread rubber is not good, which is not preferable. The weight average molecular weight (Mw) and the number average molecular weight (Mn) can be determined, for example, by gel permeation chromatography (GP).
C) can be measured.

[0010] The cis content of the butadiene rubber must be 95% or more, and preferably 97% or more. When the cis type content is less than 95%,
It is not preferable because the wear resistance of the tread rubber is not good. The cis-type content can be measured, for example, using an infrared spectrophotometer, and can be calculated according to the MORERO method.

The butadiene rubber may be used alone or in combination of two or more. Among the butadiene rubbers, cis-1,1,
4-Polybutadiene is preferred.

The isoprene-based rubber is not particularly limited, and can be appropriately selected from known rubbers. The isoprene-based rubber also includes natural rubber.

-Carbon Black- In the present invention, as the carbon black, nitrogen adsorption specific surface area (N ₂ SA), dibutyl phthalate (DB)
P) The following oil absorption amount and generated hydrogen amount are used.

[0014] The nitrogen adsorption specific surface area (N ₂ SA) needs to be 140 to 160 m ² / g.
150 to 160 m ² / g is preferred. Further, in the present invention, the nitrogen adsorption specific surface area (N ₂ SA) may be a lower limit or an upper limit of any of the above numerical ranges or the nitrogen adsorption specific surface area (N ₂ S) employed in Examples described later.
Numerical value with any value of A) as a lower limit and any lower limit or upper limit of the numerical range or any value of the nitrogen adsorption specific surface area (N ₂ SA) employed in Examples described later. Ranges are also preferred.

The nitrogen specific surface area (N ₂ SA) is 1
If it is less than 40 m ² / g, the abrasion resistance of the rubber composition is not sufficient, and if it exceeds 160 m ² / g, the dispersibility of carbon black in the rubber composition is reduced, and conversely the rubber composition On the other hand, when the abrasion resistance of the rubber composition falls within the above range, the abrasion resistance of the rubber composition can be sufficiently improved. The nitrogen adsorption specific surface area (N ₂ SA) is specified in ASTM D3037-88, and the nitrogen adsorption specific surface area per unit weight (m ² /
g).

The dibutyl phthalate (DBP) oil absorption (hereinafter sometimes referred to as "DBP oil absorption") needs to be 130 to 160 ml / 100 g, preferably 140 to 160 ml / 100 g. Further, in the present invention, as the DBP oil absorption, any lower limit or upper limit of the numerical range or any value of the DBP oil absorption adopted in the examples described below is used as a lower limit, and any one of the numerical ranges is used. It is also preferable to use a numerical range having an upper limit of any of the lower limit or upper limit or any of the DBP oil absorption amounts employed in Examples described later.

The DBP oil absorption is 130 ml / 100
If it is less than 0.1 g, the wear resistance cannot be sufficiently ensured, and
If the amount exceeds ml / 100 g, the processability and elongation characteristics are poor,
The general properties of rubber deteriorate. The DBP oil absorption is a value measured according to ASTM D2414, and means the amount (ml) of dibutyl phthalate absorbed per 100 g of carbon black.

The amount of hydrogen generated is from 1500 to 25
It is necessary to be 00 ppm.
0 ppm is preferred. Further, in the present invention, the lower limit or upper limit of any of the numerical ranges or any value of the generated hydrogen amount adopted in Examples described later is used as the lower limit of the generated hydrogen amount. It is also preferable that the lower limit or the upper limit of the above or the numerical range having the upper limit of any of the generated hydrogen amounts adopted in Examples described later.

When the amount of generated hydrogen is less than 1500 ppm, the effect of reinforcing carbon black is not sufficient,
If it exceeds 500 ppm, the elongation at break cannot be ensured, and the chipping (lack of rubber at the end of the rib) cannot be prevented. The amount of generated hydrogen can be measured, for example, by heating about 0.1 g of carbon black in an argon gas stream, and analyzing and quantifying the generated gas by a gas chromatogram.

The carbon blacks may be used alone or in combination of two or more.

The content of the carbon black in the rubber composition is as follows based on 100 parts by weight of the rubber component.
40 to 55 parts by weight are preferred. Further, in the present invention, as the content, the upper limit or lower limit of any of the numerical ranges or the value of any content adopted in the examples described below as a lower limit, any of the numerical range A numerical range in which the upper limit value or the lower limit value or the value of any of the contents employed in Examples described later is the upper limit is also preferable.

When the content of the carbon black is less than 40 parts by weight, the reinforcing effect is not sufficient, the abrasion resistance of the rubber composition cannot be sufficiently ensured, and general properties such as strength are sufficient. On the other hand, if it exceeds 55 parts by weight, the rubber composition becomes too hard, the wear resistance is rather lowered, the low heat build-up is not sufficient, and there is a risk of blowout during abnormal takeoff and landing.

-Sulfenamide Compound- The sulfenamide compound in the present invention contributes to suppression of thermal aging due to running of the rubber composition.

As the sulfenamide compound,
There is no particular limitation, and it can be appropriately selected according to the purpose. For example, N-tert-butyl-2-benzothiazoylsulfenamide (BBS), N, N′-dicyclohexyl-2-benzothiazoylsulfen Amide, N
-Cyclohexyl-2-benzothiazoylsulfenamide (CBS), N-oxydiethylene-2-benzothiazoylsulfenamide (OBS), and the like are preferable. These may be used alone or may be used alone.
More than one species may be used in combination. Moreover, these can use a commercial item suitably.

The sulfenamide compound can be used together with the sulfur, and the weight ratio to the sulfur (sulfenamide compound / sulfur) is 0.35 to
It is necessary to be 1.3, and 0.35 to 1.0 is preferable. Further, in the present invention, as the weight ratio,
The upper limit or lower limit of any of the numerical ranges or the value of any weight ratio employed in the examples described below is defined as the lower limit, and the upper limit or lower limit of any of the numerical ranges or employed in the examples described below. A numerical range having an upper limit of any of the weight ratios described above is also preferable.

The weight ratio (sulfenamide compound /
If sulfur) is less than 0.35 or more than 1.3, heat aging due to running cannot be suppressed, and the chipping (rubber chipping at the rib end) occurs. Not preferred. On the other hand, when it is within the above numerical range, the heat aging can be effectively suppressed, and it is advantageous in that there is no problem of the chipping.

[0027] The content of the sulfenamide compound in the rubber composition must be 2.5 to 3.0 parts by weight in total with the sulfur based on 100 parts by weight of the rubber component. And 2.5 to 2.8 parts by weight is preferred. Further, in the present invention, as the content, the upper limit or lower limit of any of the numerical ranges or the value of any content adopted in the examples described below as a lower limit, any of the numerical range A numerical range in which the upper limit value or the lower limit value or the value of any of the contents employed in Examples described later is the upper limit is also preferable.

If the content is less than 2.5 parts by weight or more than 3.0 parts by weight, thermal aging due to running cannot be suppressed, and the chipping (rubber at the end of the rib) cannot be prevented. Chipping) is not preferred. On the other hand, when it is within the above numerical range, the heat aging can be effectively suppressed, and it is advantageous in that there is no problem of the chipping.

-Other components- The other components can be appropriately selected and used within a range not to impair the object of the present invention. For example, inorganic fillers, softeners, vulcanizing agents such as sulfur Accelerators, such as dibenzothiazyl disulfide, vulcanization aids, zinc oxide, stearic acid, antiozonants, coloring agents, antistatic agents, lubricants, antioxidants, softeners, coupling agents, foaming agents In addition to additives such as foaming aids and the like, various compounding agents and the like usually used in the rubber industry are exemplified. These can use a commercial item suitably.

(Manufacture of Pneumatic Tire for High Speed and High Load) The method for manufacturing the pneumatic tire for high speed and high load is not particularly limited, and can be manufactured according to a known manufacturing method. For example, after preparing the rubber composition, after applying the rubber composition to a predetermined location of a high-speed high-load pneumatic tire before vulcanization, at a predetermined temperature in a predetermined mold,
The pneumatic tire for high speed and high load of the present invention can be manufactured by vulcanization molding under a predetermined pressure. In the preparation of the rubber composition, the rubber component,
A predetermined amount of the carbon black, the sulfenamide-based compound, the sulfur, and the other components appropriately selected as needed is appropriately kneaded, heated, extruded, or the like.

The conditions for the kneading are not particularly limited, and various conditions such as the volume to be charged into the kneading device, the rotation speed of the rotor, the ram pressure, the kneading temperature, the kneading time, the type of the kneading device, etc. Can be appropriately selected according to the purpose. Examples of the kneading apparatus include a Banbury mixer, an intermix, and a kneader that are usually used for kneading a rubber composition.

The heating conditions are not particularly limited, and various conditions such as a heating temperature, a heating time, and a heating device can be appropriately selected according to the purpose. As the warming device, for example, a roll machine usually used for warming a rubber composition can be used.

The conditions for the extrusion are not particularly limited, and various conditions such as an extrusion time, an extrusion speed, an extrusion apparatus, and an extrusion temperature can be appropriately selected according to the purpose. As the extruder, for example, an extruder or the like usually used for extruding a rubber composition for a tire can be used. The extrusion temperature can be appropriately determined.

At the time of the extrusion, a plasticizer such as an aroma oil, a naphthene oil, a paraffin oil, an ester oil, a liquid polyisoprene rubber, a liquid polybutadiene rubber or the like is used for the purpose of controlling the fluidity of the rubber composition. A processability improver such as a liquid polymer can be appropriately added to the rubber composition. In this case, the viscosity of the rubber composition before vulcanization can be reduced, the fluidity thereof can be increased, and extrusion can be performed very well.

There are no particular restrictions on the apparatus, system, conditions and the like for performing the vulcanization molding, and they can be appropriately selected according to the purpose. As an apparatus for performing the vulcanization molding, for example, a molding vulcanizer using a mold usually used for vulcanization of a rubber composition for a tire may be mentioned. The temperature for the vulcanization molding is usually about 100 to 190 ° C.

The pneumatic tire for high speed and high load according to the present invention
The present invention can be applied to an aircraft, a levitation traveling vehicle, and the like, and particularly to an aircraft.

[0037]

EXAMPLES Examples of the present invention will be described below, but the present invention is not limited to these examples.

(Examples 1 to 4 and Comparative Examples 1 to 4) A tread of a high-speed and high-load pneumatic tire was formed by using each rubber composition having the composition shown in Table 1, and a normal high-speed and high-load pneumatic tire was prepared. High-speed, high-load pneumatic tires for each test were manufactured according to the tire manufacturing conditions.

The weight average molecular weight (M) of the butadiene rubber in the rubber component used in the rubber composition
w), the number average molecular weight (Mn) and the cis content, the nitrogen adsorption specific surface area of the carbon black (N ₂ S
A) The amount of dibutyl phthalate (DBP) oil absorption and the amount of generated hydrogen were measured as described below.

<Weight average molecular weight (Mw) and number average molecular weight (Mn)> About 10 mg of butadiene rubber is left overnight in 20 ml of tetrahydrofuran (THF). afterwards,
Gel permeation chromatography: Measured using GPC (manufactured by Tosoh Corporation, HLC-8020 or equivalent) under the following conditions. That is, a column; two GMH _XL + H
XL-H, flow rate: 1.0 ml / min, thermostatic layer temperature: 4
0 ° C., detector: differential refractometer, detection temperature: 40 ° C., sample injection volume: 200 μl. Then, a calibration curve was prepared using the retention time (Rt) of commercially available standard polystyrene as the X axis and the molecular weight as the Y axis. The retention time from the rise of the peak to the end of the peak was subdivided at intervals of 0.2 minutes, and the peak height (Hi) at each hour was read. Further, the molecular weight (Mi) corresponding to each retention time was read from the calibration curve. Based on these, the weight average molecular weight (M
w) and the number average molecular weight (Mn) were calculated. Mn = ΣHi / Σ (Hi / Mi) Mw = ΣHi · Mi / Hi

<Cis Type Content> Measured using an infrared spectrophotometer and calculated according to the MORERO method. Specifically, it is as follows. That is, butadiene rubber about 100
To 25 g, add 25 ml of carbon disulfide and let stand for about 4 hours. The spectrum of the sample solution was measured with an infrared spectrophotometer. Then, the absorbance at the peak top of each peak was read from the spectrum data, and the cis content was calculated according to the following equation. Cis content = C × 100 / (C + V + T) C = 1.7455 × A ₇₃₈ −0.0151 × A ₉₁₀ V = 0.3746 × A ₉₁₀ −0.0070 × A ₇₃₈ T = 0.4292 × A ₉₆₆ -0.0129 × A ₉₁₀ -0.
0454 × A ₇₃₈ where A ₇₃₈ means absorbance at ₇₃₈ cm ⁻¹ . A ₉₁₀ means absorbance at 910 cm ^-1 . A ₉₆₆ means absorbance at ₉₆₆ cm ^-1 .

<Nitrogen adsorption specific surface area (N ₂ SA)> AST
Measured according to MD3037-93.

<Dibutyl phthalate (DBP) oil absorption>
Measured according to ASTM D2414-97.

<Amount of hydrogen generated> About 0.1 carbon black
g was heated in an argon gas stream, and the generated gas was analyzed and quantified using a gas chromatogram (manufactured by Shimadzu Corporation, GC-9A or its equivalent). That is, the temperature was raised at a rate of 10 ° C./min. At this time, an argon gas was introduced as a carrier gas (50 ml / min). When the temperature of the heating furnace reached 400 ° C., the gas generated from the carbon black was introduced into a gas chromatogram together with an argon gas and quantified. This measurement is performed at every 200 ° C. between 400 ° C. and 1200 ° C., and the sum of the respective temperatures is defined as the amount of generated hydrogen.
And

The treads of the obtained high-speed and high-load pneumatic tires for each test were evaluated as follows, and the results are shown in Table 1.

<Durability and Presence or Absence of Chipping> An overload take-off durability test with a taxi was performed. That is, 50 × 20. The rim assembly with the OR22 / 32 assembled to the rim was run on the drum under a load of 51800 kg at a speed of 48.3 km / h for 366 seconds.
After stopping for 17 seconds, speed from 0 km / h to 1.572
Acceleration at 7 m / s ² and 105.06 m / s (378.2
km / h) A test was performed under takeoff conditions to evaluate whether or not a tread would fail. In addition, the presence or absence of chipping (rubber chipping at the rim end) was visually evaluated.

<Abrasion resistance> JIS K 6264-19
93 vulcanized rubber was measured and calculated according to the Lambourn abrasion test method. The rubber composition used for the tread of the pneumatic tire for high speed and high load of Comparative Example 1 was indexed as 100. That is, the larger the numerical value, the better the wear resistance.

[0048]

[Table 1]

[0049] In Table 1, "(PHR)" in the composition means "parts by weight". Numerical values in the columns “BBS + sulfur” and “BBS / sulfur” mean “parts by weight”. “NR” is a natural rubber (RSS # 1). “BR” is a butadiene rubber (BR01 manufactured by JSR Corporation), and “BBS” is N-te
rt-butyl-2-benzothiazoylsulfenamide.

From the results in Table 1, the following is clear. That is, as in Comparative Example 1 (conventional example) and Comparative Example 3,
When the rubber composition used for the tread does not contain the carbon black specified in the present invention, the abrasion resistance is not sufficient. As is clear from Comparative Examples 1 and 3, when the rubber component contains butadiene rubber, it is advantageous in terms of abrasion resistance. Further, as in Comparative Example 2, even when the rubber composition used for the tread contains the carbon black specified in the present invention, the sulfenamide compound and sulfur are mixed at a predetermined weight ratio specified in the present invention. If it is not contained, chipping (lack of rubber at the end of the rib) occurs. Further, as in Comparative Example 4, when the rubber composition used for the tread does not contain the carbon black specified in the present invention, and the rubber composition used in the tread does not contain the carbon black specified in the present invention. However, the abrasion resistance is not sufficient, and further chipping (lack of rubber at the end of the rib) occurs. On the other hand, Embodiment 1 of the present invention
For treads of pneumatic tires for high speed and high load of ~ 4,
It is clear that there is no occurrence of chipping (a lack of rubber at the end of the rib) and the durability and abrasion resistance are excellent.

[0051]

According to the present invention, the above-mentioned concerns or problems in the prior art can be solved, no chipping (rubber chipping at the end of the rib) is generated, and the durability and wear resistance are excellent.
A high-speed, high-load pneumatic tire particularly suitable for aircraft and the like can be provided.

Claims (2)

[Claims] 1. The weight average molecular weight is 4.2 × 10 ⁵ or more, the ratio of the weight average molecular weight to the number average molecular weight (weight average molecular weight / number average molecular weight) is 2.0 or more, and cis type is contained. 100% by weight of a rubber component containing 0 to 40% by weight of a butadiene rubber having a ratio of 95% and 60 to 100% by weight of an isoprene-based rubber; and a nitrogen adsorption specific surface area (N ₂ SA) of 140 to 160 m ² / g.
And a dibutyl phthalate (DBP) oil absorption of 130
１６０160 ml / 100 g and the generated hydrogen amount 150
0 to 2500 ppm of carbon black 40 to 55
Parts by weight and a weight ratio (sulfenamide compound / sulfur) of 0.35
A total of 2.5 to 3.0 parts by weight of a sulfenamide compound and sulfur so as to be 1.3 to 1.3, and a tread formed of a rubber composition containing Pneumatic tire for high speed and high load. 2. The high-speed, high-load pneumatic tire according to claim 1, which is for an aircraft.