JP4262825B2 - Pneumatic tire for floating vehicles - Google Patents

Description

【００２５】
表１に示す耐久性試験結果から、カーボンブラック配合量が多い比較例１及び加硫剤の配合量が多い比較例２のいずれのタイヤもトレッドゴムがブローアウトしてゴムが飛散する故障を生しているのに対し、各実施例のタイヤのトレッドゴムには何らの異常も見出せず、試験終了後のタイヤ解剖でも故障の兆候は観察されなかった。耐摩耗性は従来例に比較して改良されており、なかでも、ＢＲ／ＮＲ比が好ましい範囲である実施例１及び２では耐摩耗性について大幅な向上が認められ、特に優れた効果を奏することがわかった。なおいずれのタイヤにもスタンディングウエーブは発生していない。
また、その他の比較例のタイヤに用いたトレッドゴムについては、トレッドゴムがブローアウトはみとめられなかったが、耐摩耗性は従来例と同等あるいはさらに劣ることがわかった。
【００２６】
【発明の効果】
本発明によれば、磁気浮上式車両用のタイヤとして、超高速で浮上走行している車両が緊急着地してもトレッドゴムとベルトとの間の接着剥離故障や高温度に基づくブローアウトなどのゴム破壊故障を生じることなく、かつスリップ走行によるトレッドゴムの早期摩耗を抑制することができる浮上式車両用空気入りタイヤを提供することができる。
【図面の簡単な説明】
【図１】本発明のタイヤの一態様を示す概略断面図である。
【符号の説明】
１ ビード部
２ サイドウォール部
３ トレッド部
４ ビードコア
５ カーカス
５ａ ターンアッププライ
５ｂ ダウンプライ
６ ベルト
６−１ 第一組コード層
６−２ 第二組コード層
６−３ 第三組ヨード層
６−４ 第四組コード層
７ トレッドゴム[0001]
BACKGROUND OF THE INVENTION
TECHNICAL FIELD The present invention relates to a pneumatic tire suitable for use in a magnetically levitated vehicle such as a linear motor car, and more particularly, a pneumatic tire for a levitated vehicle excellent in wear resistance and durability that can sufficiently cope with repeated use of a levitated vehicle. Regarding tires.
[0002]
[Prior art]
Currently, with the aim of commercialization in the near future, a magnetic levitation vehicle that is levitating using ultra-high speed vehicles and traveling at an ultra high speed is being developed as a levitation ultra high speed vehicle. This type of magnetically levitated vehicle applies a propulsive force to the vehicle by applying a magnetic force between the track side wall surface and the vehicle, and the vehicle is moved by the magnetic force acting between the track surface and the vehicle. It is of the type that enables ultra-high speed travel along the guide device.
[0003]
Tires for levitation type vehicles have a problem of adhesion peeling between the tread rubber and the belt that has a very large heat generation and a small heat transfer coefficient due to the large strain and load of the tread rubber during the emergency landing of the levitation type vehicle. Rubber breakage failure due to vulcanization return called blowout. Further, even during normal take-off and landing, local early wear of the tread rubber due to slip on the track surface of the tread rubber for a relatively long time after takeoff or landing starts is also a problem. Since the contact area of the tire is small compared to the load, a predetermined high load is applied to the tire. As a result, the amount of heat generated by the tread rubber is significant, and sometimes a standing wave is generated.
Existing vehicle tires cannot cope with the above situation, and pneumatic tires having excellent durability and stability against these heavy loads are desired.
[0004]
In order to improve the high-speed durability, for example, JP-A-3-38402 proposes a floating type radial ply tire for a vehicle in which at least one belt composed of a plurality of cord layers has a tread circumferential cord arrangement layer, In Japanese Patent Laid-Open No. 3-38408, a groove is provided at the end of the tread to reduce the amount of heat generated by the tread rubber at the end of the tread due to rolling load of the tire, and the crown radius of the end of the tread is set to the crown at the center of the tread. A floating ply radial ply tire is proposed that is smaller than the radius and has improved heat separation resistance at the belt end.
[0005]
In addition, various proposals that define the shape of the tire in order to achieve further improvement in the standing wave resistance and further improvement in wear resistance in JP-A-3-99902, JP-A-4-237605, etc. Has been made.
The floating vehicle tire disclosed in each of the publications achieves a target performance improvement and has achieved great results. However, considering the large distortion of the tread rubber and the heat generation associated therewith during the emergency landing of a floating vehicle, there is a limit to the improvement by shape.
[0006]
[Problems to be solved by the invention]
The present invention has been made in consideration of the above-mentioned problems, and an object of the present invention is to provide a tread rubber and a belt as a tire for a magnetically levitated vehicle even when a vehicle that is levitating at an ultra high speed makes an emergency landing. To provide a pneumatic tire for a floating type vehicle that can prevent a failure of rubber breakage such as a blow-out due to adhesive peeling between the tire and a high temperature, and can prevent early wear of the tread rubber due to slip traveling It is in.
[0007]
[Means for Solving the Problems]
In order to solve the above problems, the present inventors have intensively studied, and as a result, focused on the rubber composition constituting the tire, and a rubber material excellent in wear resistance, and an organic material excellent in wear resistance while suppressing aging. It has been found that the above problem can be solved by adopting a rubber containing a vulcanizing agent containing a thiosulfate compound as a tread rubber and adding carbon black with excellent wear resistance and heat resistance. The present invention has been completed.
[0008]
That is, the pneumatic tire for a floating vehicle according to the present invention is a pneumatic retire in which a belt layer and a tread portion are disposed radially outside a crown portion of a carcass layer straddling a toroidal shape between a pair of bead cores. At least a portion of the tread portion in contact with the road surface has a cis content of 95% or more, a weight average molecular weight (Mw) of 50 × 10 ⁴ or more, and a ratio Mw / Mn to the number average molecular weight (Mn) of 2. It is a blend of isoprene-based rubber including cis-polybutadiene rubber and natural rubber that is 0 or more, and the blend ratio is in a weight ratio of 60:40 to 90:10, based on 100 parts by weight of diene rubber. 40 to 55 parts by weight of the nitrogen adsorption method specific surface area (N ₂ SA) is 140 to 160 m ² / g, the DBP oil absorption is 130 to 160 ml / 100 g, and the amount of generated hydrogen is 15 Rubber formed by vulcanizing a rubber composition containing carbon black of 00 to 2500 ppm, a mixture of 2.5 to 4.0 parts by weight of sulfur and an organic thiosulfate compound represented by the following general formula It is characterized by arranging.
[0009]
[Chemical formula 2]
MO ₃ S—S— (CH ₂ ) _n —S—SO ₃ M
[0010]
In the formula, n represents 3 to 10, and M represents one equivalent of lithium, potassium, sodium, magnesium, calcium, barium, zinc, nickel, or cobalt. Moreover, you may contain crystal water in a compound.
[0011]
The rubber vulcanizing agent used in the present invention is a mixture of sulfur and an organic thiosulfate compound represented by the above general formula, and the mixing ratio is in the range of 50:50 to 20:80 by weight. It is preferable.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described in detail.
FIG. 1 is a cross-sectional view of a plane including a rotation axis of a pneumatic tire for ultra-high speed and high load.
A floating vehicle pneumatic tire (hereinafter, simply referred to as a tire as appropriate) includes a pair of bead portions 1, a pair of sidewall portions 2, and a tread portion 3. The carcass 5 extending between the bead cores 4 embedded in 1 reinforces, and the belt 6 reinforces the tread portion 3 on the outer periphery of the carcass 5. A tread rubber 7 is disposed on the outer periphery of the belt 6.
[0013]
The carcass 5 is 1 ply or more, and the illustrated example is 4 plies, of which 2 plies inside the tire are so-called turn-up plies 5a that wind up around the bead core 4 from the inside to the outside, and the remaining 2 plies are turned up The ply 5a is a down ply 5b that encloses the ply 5a, and the inner end of the tire is stopped at the bottom of the bead base. The turn-up ply 5a and the down ply 5b are both rubber-coated with a radial arrangement code, and an organic fiber cord such as nylon 66 cord is suitable for the cord.
[0014]
The belt 6 may be a laminate of ordinary cords separated at both ends, but the belt 6 is endless cords formed by winding the cords in a zigzag manner to prevent a separation failure that easily occurs from the ends of the cord layers. It is best to be a layer. Since this kind of cord layer forms one set with two layers, the belt 6 in the illustrated example has a first set cord layer 6-1 to a fourth set cord layer 6-4 sequentially from the carcass 5 side.
[0015]
The present invention is characterized by the tread rubber 7 used for the tire.
Here, the tread rubber is a diene rubber component in which the ratio of cis-polybutadiene rubber (BR) and isoprene rubber such as natural rubber is within the range of butadiene rubber: isoprene rubber = 60: 40 to 90:10. It is preferable to use it. When the butadiene-based rubber ratio is less than 60, wear due to slip behavior tends to decrease, and when it exceeds 90, cut damage and rib chipping are likely to occur.
The butadiene rubber used here has a cis content of 95% or more, furthermore, a cis content of 95 to 98%, Mw of 50 × 10 ⁴ or more, and further 55 × 10 ^{4 to} 65 ×. It is preferably 10 ⁴ , and Mw / Mn is 2.0 or more, more preferably 2.0 to 3.0. As the butadiene rubber, cis polybutadiene rubber (BR) is preferable. The isoprene-based rubber is preferably natural rubber or cis-polyisoprene rubber (IR). The preferred content of natural rubber is about 10-30.
When the Mw of the butadiene rubber is less than 50 × 10 ⁴ , the Mw / Mn is less than 2.0, or the cis content is less than 95%, the wear resistance is lowered. It is not preferable.
The tread rubber of the present invention needs to contain 40 to 55 parts by weight of carbon black with respect to 100 parts by weight of the diene rubber. If the content is less than 40 parts by weight, sufficient wear resistance cannot be exhibited, and if it exceeds 55 parts by weight, the exothermicity is lowered and blowout may occur at the time of emergency landing.
The carbon black used here preferably has a nitrogen adsorption method specific surface area (N ₂ SA) of 140 m ² / g or more and 160 m ² / g or less and a DBP oil absorption of 130 ml / 100 g or more and 160 ml / 100 g or less. . If N ₂ SA is 140 m ² / g or more and the DBP oil absorption is 130 ml / 100 g or more, good wear resistance can be secured, and if the content is less than this, wear resistance may be lowered. is there. Similarly, when N ₂ SA is 160 m ² / g or less and DBP is 160 ml / 100 g or less, good heat resistance and workability can be secured. Here, N ₂ SA is measured and calculated according to ASTM D3037, and DBP oil absorption is measured and calculated according to ASTM D2414.
[0016]
Moreover, it is preferable that the generated hydrogen amount of carbon black is in the range of 1500 to 2500 ppm. By setting the amount of generated hydrogen to 2500 ppm or less, the elongation at break can be ensured and the resistance to rib chipping can be improved. On the other hand, if the amount generated is less than 1500 ppm, the carbon black reinforcing effect may be reduced.
Here, the amount of generated hydrogen is the amount of hydrogen generated when carbon black is heated, and can be measured as follows.
About 0.1 g of carbon black is heated in an argon gas stream, and the generated gas is analyzed and quantified by a gas chromatogram. Measurement is performed under a temperature rising condition of 10 ° C./min. Argon gas is introduced as a carrier gas (inflow rate: 50 ml / min), and when the heating furnace reaches 400 ° C., the gas generated from carbon black is argon gas. In addition, it leads to gas chromatogram and quantifies it. This measurement is performed every 400 ° C. between 400 ° C. and 1200 ° C., the peak area at each temperature is calculated, the sum of the measured values at each temperature is taken as the amount of hydrogen generated, and the amount of hydrogen generated from 1 g of carbon black is The amount of hydrogen generated (ppm).
For the gas chromatogram, GC-9A manufactured by Shimadzu Corporation or its equivalent is used.
[0017]
The tread rubber of the tire of the present invention is characterized by a vulcanizing agent. That is, as a vulcanizing agent, an organic thiosulfate compound is used in combination with conventional sulfur. The vulcanizing agent made of this mixture needs to be used in a total amount of 2.5 to 4.0 parts by weight with respect to 100 parts by weight of the diene rubber component. When the amount is 2.5 parts by weight or less, a sufficient elastic modulus cannot be ensured. Moreover, when a compounding quantity exceeds 4.0 weight part, elongation at break will fall and rib chipping resistance will fall remarkably.
Here, the ratio of the organic thiosulfur soot compound to sulfur is preferably in the range of 50:50 to 20:80 by weight. If the organic thiosulfate compound ratio exceeds 50%, sufficient elastic modulus obtained when sulfur is used as a crosslinking agent may not be secured, and if it is less than 20%, the effect of improving wear resistance becomes insufficient.
The organic thiosulfate compound used here is represented by the following general formula.
[0018]
[Chemical 3]
MO ₃ S—S— (CH ₂ ) _n —S—SO ₃ M
[0019]
In the formula, the number of methylene chains represented by n needs to be 3 to 10, and if it is 2 or less, the effect of improving the wear resistance is not sufficiently obtained, and if it is 11 or more, the wear resistance is improved although the molecular weight increases. Small effect. Furthermore, it is desirable that the methylene chain is 3 to 6 from the viewpoint of suppressing the intramolecular cyclization reaction.
M represents one equivalent of lithium, potassium, sodium, magnesium, calcium, barium, zinc, nickel, or cobalt, and potassium, sodium, and the like are preferable in view of availability and effects.
This compound may be a hydrate having crystal water in the molecule.
Specific examples of this compound include sodium salt monohydrate, sodium salt dihydrate and the like. For economic reasons, a derivative from sodium thiosulfate, such as sodium 1,6-hexamethylenedithiosulfate. • Dihydrate is most suitable.
[0020]
As described above, the tire of the present invention using the vulcanized rubber having excellent durability and wear resistance as the tread rubber has a high load load and travels at an ultra high speed of 380 to 550 km / h. Exerts its best performance when applied to tires.
[0021]
【Example】
EXAMPLES Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited thereto.
A rubber composition for tread rubber was blended according to the blending shown in Table 1 below. As the organic thiosulfate compound, sodium 1,6-hexamethylenedithiosulfate dihydrate was used.
The molecular weight (Mw, Mn) and cis content of the butadiene rubber (BR) used in this rubber composition were measured as follows. The results are shown in Table 1.
(1) Measurement of molecular weight (Mw, Mn) About 100 mg of BR is weighed and left overnight in 20 ml of THF. Measurement is performed under the following conditions using GPG (HLC-8020 manufactured by Tosoh Corporation).
Column ... GMH _XL 2 + HXL-H
Flow rate: 1.0ml / min
Constant temperature layer temperature: 40 ° C
Detector: Differential refractometer detection temperature: 40 ° C
Sample injection fee: 200 μl
-A calibration curve is taken with the retention time (Rt) of commercially available standard polystyrene on the X axis and the molecular weight on the Y axis.
-The retention time from the peak rise to the peak end is subdivided in increments of 0.2 minutes, and the peak height (Hi) for each retention time is read. Further, the molecular weight (Mi) corresponding to each retention time is obtained from a calibration curve.
-Mw and Mn are calculated | required with the following formula | equation.
Mn = ΣHi / Σ (Hi / Mi)
Mw = ΣHiMi / Hi
(2) Calculated by the MORERO method using a cis content infrared spectrophotometer.
[0022]
Further, the physical properties of the carbon black used in the rubber composition were also measured by the following method, and the results are shown in Table 1.
(3) Nitrogen adsorption specific surface area (N ₂ SA)
The measurement was calculated according to ASTM D3037.
(4) DBP oil absorption was measured and calculated according to ASTM D2414.
(5) Amount of generated hydrogen About 0.1 g of carbon black is heated in an argon gas stream, and the generated gas is analyzed and quantified with a gas chromatogram (GC-9A manufactured by Shimadzu Corporation). Measurement is performed under a temperature rising condition of 10 ° C./min. Argon gas is introduced as a carrier gas (inflow rate: 50 ml / min), and when the heating furnace reaches 400 ° C., the gas generated from carbon black is argon gas. In addition, it leads to gas chromatogram and quantifies it. This measurement is performed every 400 ° C. between 400 ° C. and 1200 ° C., the peak area at each temperature is calculated, the sum of the measured values at each temperature is taken as the amount of hydrogen generated, and the amount of hydrogen generated from 1 g of carbon black is The amount of hydrogen generated (ppm).
[0023]
Using the rubber composition shown in Table 1 as a tread rubber, radial tires having the structure shown in FIG. 1 were prepared and used as tires (E195 / 80R22) of Examples, Conventional Examples, and Comparative Examples.
Tires and rim assemblies in which the tires of Examples, Conventional Examples, and Comparative Examples are used as test tires, and these tires are assembled to the rim (nominal diameter 22) described above and filled with a specified internal pressure of 20.7 kgf / cm ^2. A high-speed, high-load durability test was conducted to determine whether or not the tread rubber would fail after landing on a 300 cm diameter drum rotating at 550 km / h from a non-rotating state with a load of 6600 kgf and running for 104 minutes. Carried out.
As for the wear resistance, a Lambourn wear test was carried out in the vulcanized rubber wear test method of JIS K 6264 (1995), and the test conditions were standard test conditions. The test results are represented by an index with the conventional example being 100, and the larger the index value, the better. These test results are shown in the columns of durability and wear resistance in Table 1.
[0024]
[Table 1]

[0025]
From the durability test results shown in Table 1, both the tires of Comparative Example 1 with a large amount of carbon black and Comparative Example 2 with a large amount of vulcanizing agent cause a failure in which the tread rubber blows out and the rubber scatters. On the other hand, no abnormality was found in the tread rubber of the tire of each example, and no signs of failure were observed in the tire dissection after completion of the test. The wear resistance is improved as compared with the conventional example. In particular, in Examples 1 and 2 in which the BR / NR ratio is in a preferable range, a significant improvement in the wear resistance is recognized, and particularly excellent effects are exhibited. I understood it. None of the tires had a standing wave.
Further, regarding the tread rubber used in the tires of other comparative examples, the tread rubber did not show blowout, but the wear resistance was found to be equal to or worse than that of the conventional example.
[0026]
【The invention's effect】
According to the present invention, as a tire for a magnetically levitated vehicle, even if a vehicle that is levitating at an ultra high speed lands on an emergency landing failure such as an adhesive separation between a tread rubber and a belt or a blowout based on a high temperature. There can be provided a pneumatic tire for a floating type vehicle that is capable of suppressing the early wear of the tread rubber due to slip traveling without causing a rubber breakdown failure.
[Brief description of the drawings]
FIG. 1 is a schematic cross-sectional view showing one embodiment of a tire of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Bead part 2 Side wall part 3 Tread part 4 Bead core 5 Carcass 5a Turn-up ply 5b Down ply 6 Belt 6-1 1st group cord layer 6-2 2nd group cord layer 6-3 3rd group iodine layer 6-4 4th cord layer 7 tread rubber

Claims (2)

In a pneumatic retire in which a belt layer and a tread portion are disposed on a radially outer side of a crown portion of a carcass layer straddling a toroidal shape between a pair of bead cores,
At least a portion of the tread portion in contact with the road surface has a cis content of 95% or more, a weight average molecular weight (Mw) of 50 × 10 ⁴ or more, and a ratio Mw / Mn to the number average molecular weight (Mn) of 2. It is a blend of isoprene-based rubber including cis-polybutadiene rubber and natural rubber that is 0 or more, and the blend ratio is in a weight ratio of 60:40 to 90:10, based on 100 parts by weight of diene rubber. 40 to 55 parts by weight of a carbon black having a nitrogen adsorption method specific surface area (N ₂ SA) of 140 to 160 m ² / g, a DBP oil absorption of 130 to 160 ml / 100 g, and a hydrogen generation amount of 1500 to 2500 ppm A rubber composition obtained by vulcanizing a rubber composition containing 2.5 to 4.0 parts by weight of sulfur and an organic thiosulfate compound represented by the following general formula: Pneumatic tire for floating vehicles.
[Chemical 1]
MO ₃ S—S— (CH ₂ ) _n —S—SO ₃ M
In the formula, n represents 3 to 10, and M represents one equivalent of lithium, potassium, sodium, magnesium, calcium, barium, zinc, nickel, or cobalt. Moreover, you may contain crystal water in a compound. 2. The floating vehicle pneumatic tire according to claim 1, wherein a mixing ratio of the mixture of the organic thiosulfate compound represented by the general formula and the sulfur is in a range of 50:50 to 20:80 by weight.

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