JPH07118443A - Radial tire for track and bus - Google Patents
Radial tire for track and busInfo
- Publication number
- JPH07118443A JPH07118443A JP5268537A JP26853793A JPH07118443A JP H07118443 A JPH07118443 A JP H07118443A JP 5268537 A JP5268537 A JP 5268537A JP 26853793 A JP26853793 A JP 26853793A JP H07118443 A JPH07118443 A JP H07118443A
- Authority
- JP
- Japan
- Prior art keywords
- rubber
- weight
- tire
- wear resistance
- base
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
Landscapes
- Tires In General (AREA)
- Compositions Of Macromolecular Compounds (AREA)
Abstract
Description
【０００１】[0001]
【産業上の利用分野】本発明は、トラック・バス用ラジ
アルタイヤに関し、特にタイヤの高速耐久性を損なうこ
となく、耐摩耗性と耐偏摩耗性が大幅に改善された重荷
重用ラジアルタイヤに関するものである。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a radial tire for trucks and buses, and more particularly to a radial tire for heavy loads whose wear resistance and uneven wear resistance are significantly improved without impairing the high speed durability of the tire. Is.
【０００２】[0002]
【従来の技術】従来よりトラック・バス用ラジアルタイ
ヤの耐摩耗性、耐偏摩耗性と高速耐久性とを同時に改良
するために、タイヤトレッド部を厚み方向に２分し、キ
ャップゴムとベースゴムの２層から構成したタイヤが提
供されている。これは一層からなるゴムを使用してトレ
ッド部全体の耐摩耗性及び耐偏摩耗性を向上させようと
すると、一般にタイヤの発熱温度が高くなり高速耐久性
が低下するので、その対策として、外側のキャップゴム
に耐摩耗性及び耐偏摩耗性の良好なゴム組成物を配し、
内側のベースゴムに剛性の低い低発熱性ゴムを配して、
タイヤに耐摩耗性と耐偏摩耗性並びに低発熱性を同時に
兼備させようとしたものである。この種タイヤのベース
ゴムの厚みは全トレッドの厚みの２５％以下、その多く
は１０〜２０％の範囲に限定されていた。2. Description of the Related Art Conventionally, in order to simultaneously improve wear resistance, uneven wear resistance and high speed durability of radial tires for trucks and buses, a tire tread portion is divided into two parts in a thickness direction, a cap rubber and a base rubber. There is provided a tire composed of two layers. This is because if you try to improve the wear resistance and uneven wear resistance of the entire tread part by using rubber consisting of one layer, the heat generation temperature of the tire generally increases and the high-speed durability decreases, so as a countermeasure, A rubber composition having good wear resistance and uneven wear resistance is arranged on the cap rubber of
By arranging low-rigidity rubber with low rigidity on the inner base rubber,
The tire is intended to have both abrasion resistance, uneven abrasion resistance and low heat buildup at the same time. The thickness of the base rubber of this kind of tire was 25% or less of the thickness of the entire tread, and most of them were limited to the range of 10 to 20%.
【０００３】そして、上記のごとき２層構造からなるト
レッドのキヤップゴムとしては、これまで天然ゴムまた
は天然ゴムに少量のシス-1.4- ポリプタジエンゴム（以
下、シスＢＲと略記する）をブレンドしてなるゴム分に
ＩＳＡＦカーボンブラック（CTAB 110 m2 /g前後）やＳ
ＡＦカーボンブラック（CTAB 130 m2 /g前後）を４０〜
５０ phr配合してなるゴム組成物が、また、これと組み
合わすベースゴムには３００％引張応力が１０〜１３ M
Pa程度の低い剛性を有する低発熱性天然ゴム組成物が主
として使用されてきた。また、上記のシスＢＲとして
は、比較的低分子量で分岐度が高く、分子量分布が広い
汎用タイプのシスＢＲ（例えば、日本合成ゴム株式会社
製 商品名 ＢＲ０２）が一般に採用されてきた。As a cap rubber for a tread having a two-layer structure as described above, a natural rubber or a natural rubber blended with a small amount of cis-1.4-polyptadiene rubber (hereinafter abbreviated as cis BR) has hitherto been used. ISAF carbon black (CTAB 110 m 2 / g or so) and S
AF carbon black (CTAB around 130 m 2 / g) 40 ~
A rubber composition containing 50 phr and a base rubber combined with this has a 300% tensile stress of 10 to 13 M.
Low exothermic natural rubber compositions having a rigidity as low as Pa have been mainly used. As the cis BR, a general-purpose cis BR having a relatively low molecular weight, a high degree of branching, and a wide molecular weight distribution (for example, BR02 manufactured by Nippon Synthetic Rubber Co., Ltd.) has been generally adopted.
【０００４】ところで、最近の耐摩耗性競争に対処する
ため、天然ゴムに添加する上記汎用タイプのシスＢＲの
ブレンド比率を高めると、キャップゴムの耐摩耗性はこ
れに伴って向上するが、キャップゴムの剛性が低くな
り、タイヤの発熱温度が上昇して高速耐久性が低下する
と共に、トレッド全体の剛性の低下を招き偏摩耗が生じ
易くなる。また、従来品より更に粒子径の小さいカーボ
ンブラックを使用したり添加量を増加してキャップゴム
の補強性を高めると、耐摩耗性は改良されるがキャップ
ゴムの高発熱化を招き、ベルトセパレーションなど熱に
よるタイヤの破壊が起こり易くなって高速耐久性が低下
するという問題があった。By the way, if the blending ratio of the above-mentioned general-purpose type cis BR added to natural rubber is increased in order to cope with the recent competition in wear resistance, the wear resistance of the cap rubber is improved accordingly. The rigidity of the rubber decreases, the heat generation temperature of the tire rises, the high-speed durability decreases, and the rigidity of the tread as a whole decreases and uneven wear easily occurs. In addition, if carbon black with a smaller particle size than the conventional product is used or the amount of carbon black is increased to enhance the reinforcing property of the cap rubber, wear resistance is improved, but the cap rubber will generate high heat and the belt separation As a result, there is a problem that the tire is likely to be damaged by heat and high-speed durability is deteriorated.
【０００５】一方、ベースゴムには通常ＨＡＦカーボン
ブラック（CTAB 80 m2 /g前後) 乃至はＩＳＡＦカーボ
ンプラックを使用し、かつその配合量を比較的ローレベ
ルとして３００％引張応力を１０〜１３ MPa程度に調整
した低発熱性天然ゴム組成物が用いられているが、上記
のごときキャップゴムに基因する発熱温度の上昇を抑制
するため、更にベースゴムの低発熱化を図ろうとする
と、剛性が小さくなり過ぎて機械的強度が低下し、ブロ
ックティアやリブティア、或いは偏摩耗が起こり易くな
ると同時に、走行中タイヤに働く力を路面に伝達する機
能が損なわれて好ましくない。そこで、ベースゴムに従
来タイプのゴム組成物を使用し、トレッド全体の厚さに
対するベースゴムの厚さの比（ＴB ／ＴA ）を大きくし
てタイヤの発熱温度を下げようとすると、逆にタイヤ温
度が上昇するという結果を招く。On the other hand, as the base rubber, usually HAF carbon black (CTAB 80 m 2 / g or so) or ISAF carbon plaque is used, and the compounding amount thereof is set to a relatively low level to obtain a 300% tensile stress of 10 to 13 MPa. A low exothermic natural rubber composition adjusted to a certain degree is used, but in order to suppress the rise in exothermic temperature due to the cap rubber as described above, if it is attempted to further reduce the heat generation of the base rubber, the rigidity becomes small. It is not preferable because the mechanical strength is lowered too much, block tiers, rib tiers, and uneven wear are likely to occur, and at the same time, the function of transmitting the force acting on the tire during traveling to the road surface is impaired. Therefore, if a conventional type rubber composition is used as the base rubber and the ratio of the thickness of the base rubber to the thickness of the entire tread (T B / T A ) is increased to reduce the heat generation temperature of the tire, the reverse occurs. This will result in an increase in tire temperature.
【０００６】[0006]
【発明が解決しようとする課題】本発明は、叙上のごと
き実情に鑑みなされたものであって、その目的とすると
ころは、少なくとも従来タイヤに比較して同等乃至それ
以上の高速耐久性を備えると共に、耐摩耗性と耐偏摩耗
性が大幅に改善されたトラック・バス用ラジアルタイヤ
を提供することにある。SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned circumstances, and its object is to achieve high-speed durability at least equal to or higher than that of conventional tires. (EN) Provided is a radial tire for trucks / buses, which is equipped with and has significantly improved wear resistance and uneven wear resistance.
【０００７】[0007]
【課題を解決するための手段】上記の目的を達成するた
め鋭意研究を重ねた結果、キャップ／ベース２層構造か
らなるトレッドのキャップゴムに配合するシスＢＲのマ
クロ構造とカーボンブラックのコロイダル特性を特定す
ると共に、ベースゴムのモジュラスとトレッド全体に占
める厚みの比を適切に組み合わせることにより、所期の
目的が達成し得ることを見出だし、本発明を完成するに
至った。即ち、本発明は、トレッドがキャップゴムとベ
ースゴムの２層構造からなるトラック・バス用ラジアル
タイヤにおいて、該キャップゴムとして、天然ゴムまた
は天然ゴムと合成ポリイソプレンゴムとのブレンドゴム
８５重量部と、重量平均分子量（Ｍｗ）が５０×１０4
〜７５×１０4 の範囲にあり、該重量平均分子量（Ｍ
ｗ）と数平均分子量（Ｍｎ）との比で示される分子量分
布（Ｍｗ／Ｍｎ）が１．５〜３．０の範囲にあり、かつ
２３℃のトルエン溶液中の固有粘度［η］が９０以上で
あるシス-1.4- ポリブタジエンゴム（以下、改質−シス
ＢＲと略記する）１５〜５０重量部とよりなるゴム分１
００重量部に対し、セチルトリメチルアンモニウムブロ
マイド吸着比表面積（CTAB) が１３５〜１６０ m2 /gの
範囲にあるカーボンブラックを４５〜６５重量部配合し
てなるゴム組成物を用い、また該ベースゴムとして３０
０％引張応力（B-Ｍ300 ）が１６ MPa以上のゴム組成物
を用いると共に、ベースゴムの厚さ（ＴB ）のトレッド
ゴムの全厚さ（ＴA ）に対する比（ＴB ／ＴA ）を０．
２５〜０．４０の範囲に設定してなることを特徴とする
トラック・バス用ラジアルタイヤをその要旨とする。[Means for Solving the Problems] As a result of intensive studies to achieve the above-mentioned object, the macro structure of cis BR and the colloidal characteristics of carbon black compounded in a cap rubber of a tread having a cap / base two-layer structure were determined. The present invention has been accomplished by finding out that the intended purpose can be achieved by specifying and appropriately combining the modulus of the base rubber and the ratio of the thickness of the entire tread. That is, the present invention relates to a radial tire for trucks / buses in which the tread has a two-layer structure of a cap rubber and a base rubber, and as the cap rubber, 85 parts by weight of natural rubber or a blend rubber of natural rubber and synthetic polyisoprene rubber is used. , The weight average molecular weight (Mw) is 50 × 10 4.
To 75 × 10 4 , and the weight average molecular weight (M
w) and the number average molecular weight (Mn) have a molecular weight distribution (Mw / Mn) represented by a ratio of 1.5 to 3.0, and an intrinsic viscosity [η] in a toluene solution at 23 ° C. is 90. A rubber component 1 comprising 15 to 50 parts by weight of the above cis-1.4-polybutadiene rubber (hereinafter abbreviated as modified-cis BR).
A rubber composition comprising 45 to 65 parts by weight of carbon black having a cetyltrimethylammonium bromide adsorption specific surface area (CTAB) in the range of 135 to 160 m 2 / g with respect to 00 parts by weight is used. As 30
A rubber composition having a 0% tensile stress (B-M300) of 16 MPa or more is used, and the ratio of the thickness of the base rubber (T B ) to the total thickness of the tread rubber (T A ) (T B / T A ) 0.
The gist thereof is a radial tire for trucks and buses, which is characterized by being set in a range of 25 to 0.40.
【０００８】本発明に係わる改質−シスＢＲは、シス-
1.4結合を９７％以上含有し、上記のごとき特定なマク
ロ構造を有するポリブタジエンであって、汎用タイプの
シスＢＲと比較すると、分子量が大きく、分子量分布が
狭くて、直鎖状傾向が高いという特徴を備えている。し
かし、これを天然ゴムにブレンドした時、タイヤの低発
熱性、耐摩耗性、耐偏摩耗性が同時にバランスよく向上
するには、その重量平均分子量（Ｍｗ）と分子量分布
（Ｍｗ／Ｍｎ）並びに固有粘度［η］がそれぞれ下記の
ごとき条件を満足するものでなければならない。 ５０×１０4 ≦ Ｍｗ ≦ ７５×１０4 １．５ ≦ Ｍｗ／Ｍｎ ≦ ３．０ ［η］ ≧ ９０The modified-cis BR according to the present invention is a cis-
A polybutadiene containing 1.4% or more of 97% and having a specific macrostructure as described above, which has a large molecular weight, a narrow molecular weight distribution, and a high linear tendency as compared with general-purpose type cis BR. Is equipped with. However, when this is blended with natural rubber, in order to simultaneously improve the low heat build-up, wear resistance, and uneven wear resistance of the tire in a well-balanced manner, its weight average molecular weight (Mw) and molecular weight distribution (Mw / Mn) and The intrinsic viscosity [η] must satisfy the following conditions. 50 × 10 4 ≦ Mw ≦ 75 × 10 4 1.5 ≦ Mw / Mn ≦ 3.0 [η] ≧ 90
【０００９】Ｍｗが５０×１０4 未満では、配合ゴムの
ヒステリシスロスが大きくなってタイヤの発熱温度の上
昇をまねき、引張強度、引裂強度などの耐破壊特性が低
下して、疲労摩耗や偏摩耗、或いはティアが生じ易くな
る。Ｍｗが７５×１０4 より大きくなると、カーボンブ
ラック及びポリマーの分散が悪くなって耐摩耗性が低下
する。また、分子量分布が更に狭くて、Ｍｗ／Ｍｎ値が
１．５未満になるとカーボンブラックやポリマー分散が
悪くなり、３．０以上ではヒステリシスロスが大きくな
ってタイヤの発熱温度が上昇すると共に、耐破壊特性が
低下して耐摩耗性や耐偏摩耗性が劣化する。固有粘度に
ついては、［η］が９０より小さくてポリマーの分岐度
が高くなると、配合ゴムのヒステリシスロスが上昇して
耐疲労摩耗性や耐偏摩耗性が低下するので好ましくな
い。If the Mw is less than 50 × 10 4 , the hysteresis loss of the compounded rubber becomes large and the heat generation temperature of the tire rises, and the fracture resistance characteristics such as tensile strength and tear strength deteriorate, resulting in fatigue wear and uneven wear. Or, a tier is likely to occur. When Mw is larger than 75 × 10 4 , the carbon black and the polymer are poorly dispersed and the abrasion resistance is lowered. Further, when the molecular weight distribution is narrower and the Mw / Mn value is less than 1.5, carbon black or polymer dispersion becomes poor, and when it is 3.0 or more, the hysteresis loss becomes large and the tire heat generation temperature rises, and the The fracture characteristics are reduced and the wear resistance and uneven wear resistance are deteriorated. Regarding the intrinsic viscosity, if [η] is smaller than 90 and the degree of branching of the polymer is high, the hysteresis loss of the compounded rubber is increased and the fatigue wear resistance and uneven wear resistance are reduced, which is not preferable.
【００１０】かかる改質−シスＢＲと天然ゴムとのブレ
ンド比率は、天然ゴム８５〜５０重量部当たり１５〜５
０重量部が適当である。この場合にも、ブレンド比率の
増加につれて発熱温度は上昇するが、上記のブレンド比
率の範囲では、汎用タイプのシスＢＲを使用するより
も、はるかに低発熱性のゴム組成物が得られる。この際
改質−シスＢＲとブレンドするゴム成分としては通常天
然ゴムが好ましく使用されるが、場合によりこの天然ゴ
ムに所定量の合成ポリイソプレンゴムをブレンドするこ
とも可能である。改質−シスＢＲの上記ブレンド比率が
１５重量部未満では耐摩耗性の改良効果が小さく、ま
た、５０重量部を越えて大きくなると配合ゴムの剛性が
落ちるから、タイヤの発熱が上昇して高速耐久性が低下
し、耐偏摩耗性の劣化を生じ好ましくない。The blending ratio of such modified-cis BR and natural rubber is 15 to 5 per 85 to 50 parts by weight of natural rubber.
0 parts by weight is suitable. In this case as well, the exothermic temperature rises as the blending ratio increases, but in the range of the above blending ratio, a rubber composition having a much lower heat generation than that using a general-purpose type cis BR can be obtained. At this time, natural rubber is usually preferably used as the rubber component to be blended with the modified-cis BR, but it is also possible to blend a predetermined amount of synthetic polyisoprene rubber with the natural rubber in some cases. If the blending ratio of the modified-cis BR is less than 15 parts by weight, the effect of improving the wear resistance is small, and if it exceeds 50 parts by weight, the rigidity of the compounded rubber decreases, so that the heat generation of the tire increases and high speed is achieved. It is not preferable because durability is lowered and uneven wear resistance is deteriorated.
【００１１】本発明においては、従来のＳＡＦカーボン
ブラックより更に粒子径の小さい（CTAB値の大きい）カ
ーボンブラックを使用してキャップゴムの耐摩耗性向上
を図ろうとするものであるが、そのコロイダル特性値と
配合量の範囲は、つぎのような理由に基づき定められた
ものである。即ち、CTABが１３５ m2 /g未満の場合は耐
摩耗性向上効果が乏しく、１６０ m2 /gを越えると発熱
温度が上昇すると共に加工性が悪化してしまうので、CT
ABは１３５〜１６５ m2 /gの範囲のものを使用する。ま
た、配合量が４５重量部未満の場合は耐摩耗効果が乏し
く、６５重量部を越えると発熱が高くなって高速耐久性
が低下し、かつ加工性が悪化するので配合量は４５〜６
５重量部の範囲とする。In the present invention, carbon black having a smaller particle size (larger CTAB value) than conventional SAF carbon black is used to improve the wear resistance of the cap rubber. The range of the value and the blending amount is determined based on the following reasons. That is, when CTAB is less than 135 m 2 / g, the effect of improving wear resistance is poor, and when it exceeds 160 m 2 / g, the heat generation temperature rises and the workability deteriorates.
AB is in the range of 135 to 165 m 2 / g. Further, if the blending amount is less than 45 parts by weight, the abrasion resistance effect is poor, and if it exceeds 65 parts by weight, heat generation becomes high, high-speed durability deteriorates, and workability deteriorates.
The range is 5 parts by weight.
【００１２】前記の通り、ベースゴムに従来タイプの低
モジュラスゴム組成物を使用した場合には、トレッド全
厚さに対するベースゴムの厚さの比（ＴB ／ＴA ）を大
きくしてもタイヤの発熱温度を低下することはできな
い。この種のベース用ゴム組成物はキャップゴムのそれ
より低発熱性であるが、３００％引張応力（B-Ｍ300 ）
が１０〜１３ MPa程度と小さく剛性が低いので、ベース
ゴムの厚さの増加分だけベースにトレッド全体の歪みが
集中して、このような結果を生ずるものと考えられる。As described above, when the conventional low modulus rubber composition is used as the base rubber, the tire is increased even if the ratio (T B / T A ) of the thickness of the base rubber to the total thickness of the tread is increased. The exothermic temperature of can not be lowered. This type of base rubber composition has lower exothermicity than that of cap rubber, but has a 300% tensile stress (B-M300).
Is as low as about 10 to 13 MPa, and the rigidity is low, and it is considered that the strain of the entire tread is concentrated on the base by the increase in the thickness of the base rubber, and such a result is produced.
【００１３】そこで、本発明においては、キャップゴム
と組み合わせるベースゴムに、大変形時の剛性に対応す
る３００％引張応力（B-Ｍ300 ) が１６ MPa以上のゴム
組成物を使用すると共に、ＴB ／ＴA 比を０．２５〜
０．４０の範囲に特定してベースを厚くしたところ、ベ
ースに集中していた歪みが適度に分散されてトレッド全
体の発熱を低下することが可能となった。なおこの場
合、ＴB ／ＴA が０．２５未満ではキャップゴムに基因
する発熱を充分相殺し得ずにタイヤの発熱が高くなり、
０．４０を越えると発熱抑制には有利だが、ベースゴム
の耐摩耗性はキャップのそれに劣るからタイヤ全体して
の摩耗寿命が低下して好ましくない。Therefore, in the present invention, a rubber composition having a 300% tensile stress (B-M300) of 16 MPa or more, which corresponds to the rigidity at the time of large deformation, is used as the base rubber combined with the cap rubber, and T B / T A ratio of 0.25
When the base was made thicker by specifying it in the range of 0.40, the strain concentrated in the base was dispersed appropriately, and it became possible to reduce the heat generation of the entire tread. In this case, if T B / T A is less than 0.25, the heat generation due to the cap rubber cannot be sufficiently offset, and the heat generation of the tire becomes high.
If it exceeds 0.40, it is advantageous for suppressing heat generation, but since the wear resistance of the base rubber is inferior to that of the cap, the wear life of the entire tire is shortened, which is not preferable.
【００１４】このベースゴムに使用されるゴム成分とし
ては、天然ゴムの他、ポリイソプレンゴム、ポリブタジ
エンゴム、ポリスチレンーブタジエンゴム等のジエン系
合成ゴムの少なくとも一種からなるゴム成分であればい
ずれも使用可能であるが、発熱性、破壊特性、加工性等
に優れた天然ゴムが最も好ましい。また、ベースゴムの
３００％引張応力（B-Ｍ300 ）を１６ MPa以上に調整す
るには、通常、CTABが１００〜１３０の範囲にあるカー
ボンブラックを使用し、その配合量をゴム分１００重量
部当たり３５〜５０重量部の範囲で調節することによっ
て達成される。As the rubber component used for the base rubber, any rubber component other than natural rubber may be used as long as it is at least one kind of diene synthetic rubber such as polyisoprene rubber, polybutadiene rubber, polystyrene-butadiene rubber and the like. Although possible, natural rubber, which is excellent in heat generation property, breaking property, processability, etc., is most preferable. Further, in order to adjust the 300% tensile stress (B-M300) of the base rubber to 16 MPa or more, carbon black having a CTAB in the range of 100 to 130 is usually used, and its compounding amount is 100 parts by weight of the rubber content. It is achieved by adjusting in the range of 35 to 50 parts by weight.
【００１５】なお、本発明においては、上記成分の他に
通常用いられている配合剤、例えば加硫剤、加硫促進
剤、加硫促進助剤、老化防止剤、プロセス油、その他の
加工助剤等が適宜添加され得ることはいうまでもない。In the present invention, in addition to the above-mentioned components, commonly used compounding agents such as vulcanizing agents, vulcanization accelerators, vulcanization accelerating aids, antioxidants, process oils and other processing aids. It goes without saying that agents and the like can be added as appropriate.
【００１６】[0016]
【作用】本発明においては、キャップゴムに特定なマク
ロ構造を有する改質−シスＢＲを配合すると共に、ＳＡ
Ｆカーボンブラックより更に小粒子径のカーボンブラッ
クを使用したので、走行初期の耐摩耗性が一段と向上す
る。また、かかるキャップゴムと組み合わせるベースゴ
ムのモジュラスを高め、かつベースゴムの厚みを特定の
範囲で従来より大きく設定したので、キャップゴムの補
強性を高めたにも拘らずタイヤ全体の発熱を低下するこ
とが可能となった。これにより、タイヤの耐摩耗性と耐
偏摩耗性並びに高速耐久性をバランスよく改善すること
ができる。In the present invention, the cap rubber is blended with a modified-cis BR having a specific macro structure and SA
Since carbon black having a smaller particle size than that of F carbon black is used, the wear resistance at the initial stage of running is further improved. Further, since the modulus of the base rubber combined with the cap rubber is increased and the thickness of the base rubber is set to be larger than the conventional range in a specific range, heat generation of the tire as a whole is reduced despite the reinforcement of the cap rubber being enhanced. It has become possible. This makes it possible to improve the wear resistance, uneven wear resistance, and high-speed durability of the tire in a well-balanced manner.
【００１７】[0017]
【実施例】以下に実施例及び比較例を挙げて本発明を具
体的に説明する。表１と表２は、それぞれキャップゴム
に使用されるシスＢＲの種類とその特性及びカーボンブ
ラックの CTAB 値を示したものである。EXAMPLES The present invention will be specifically described below with reference to Examples and Comparative Examples. Tables 1 and 2 show the types and properties of cis BR used for cap rubbers, and the CTAB value of carbon black.
【表１】 なお、表１におけるシス含量は赤外分光光度計により測
定された。重量平均分子量（Ｍｗ）及び分子量分布（Ｍ
ｗ／Ｍｎ）はＴＨＦを展開溶媒としてゲルパーミエーシ
ョンクロマトグラフィーにより測定されたものである。
また、固有粘度［η］は２３℃のトルエン溶液中ウベロ
ーデ粘度計により測定された値である。[Table 1] The cis content in Table 1 was measured by an infrared spectrophotometer. Weight average molecular weight (Mw) and molecular weight distribution (M
w / Mn) is measured by gel permeation chromatography using THF as a developing solvent.
The intrinsic viscosity [η] is a value measured by an Ubbelohde viscometer in a toluene solution at 23 ° C.
【表２】 表２に示すカーボンブラックのセチルトリメチルアンモ
ニウムブロマイド吸着比表面積（CTAB) はＡＳＴＭ Ｄ
3765に準拠して測定された値である。[Table 2] The cetyltrimethylammonium bromide adsorption specific surface area (CTAB) of carbon black shown in Table 2 is ASTM D
It is a value measured according to 3765.
【００１８】表３は、キャップゴム及びベースゴムに使
用される各ゴム組成物の配合を示したものである。Table 3 shows the composition of each rubber composition used for the cap rubber and the base rubber.
【表３】 [Table 3]
【００１９】この基本的配合組成に表５及び表６に示す
天然ゴムとシスＢＲとのブレンド比率及びカーボンブラ
ック各部を適用してキャップ用ゴム組成物を構成した。
また、表３におけるベースゴムのゴム分は天然ゴムであ
り、該ゴム１００重量部当たりＩＳＡＦカーボンブラッ
クの配合量を変量することによって、表４に示すごとき
モジュラス（B-Ｍ300 ）を有するベース用ゴム組成物を
えた。A rubber composition for a cap was constructed by applying the blending ratio of natural rubber and cis BR and each part of carbon black shown in Tables 5 and 6 to this basic compounding composition.
The rubber content of the base rubber in Table 3 is natural rubber, and the base rubber having a modulus (B-M300) as shown in Table 4 is obtained by varying the compounding amount of ISAF carbon black per 100 parts by weight of the rubber. The composition was obtained.
【表４】 表４には、これらのキャップとベース用ゴム組成物を用
いてタイヤを製造するに当たり、各ベースゴムに特定し
て設定されるＴB ／ＴA 比が付加されている。[Table 4] In Table 4, when manufacturing a tire using these caps and the rubber composition for a base, the T B / T A ratio set specifically for each base rubber is added.
【００２０】[0020]
【表５】 [Table 5]
【表６】 [Table 6]
【００２１】次いで、これらのキャップ及びベース用ゴ
ム組成物を組合わせて、1000 R 2014PRのラジアルタイ
ヤを常法により作成し、下記の方法により性能評価を実
施した。 耐摩耗性： 高速道路を１０万km走行させた後、リヤ装
着タイヤのトレッド溝の摩耗ミリ当たり走行距離を求
め、比較例１の従来型キャップ／ベース構造タイヤの値
を１００として指数表示したもので、数値の大きい方が
良好である。 耐偏摩耗性： 高速道路を１０万km走行させた後、フロ
ント装着タイヤのクラウン部リブ高さの平均値とショル
ダー部リブ高さの平均値を測定し、これより肩落ち摩耗
ミリ当たりの走行距離（１mmの段差が生ずるまでの走行
距離）を求め、比較例１のタイヤを１００として指数表
示したもので数値の大きい方が良好である。 発熱性： ＦＭＶＳＳ 119 に規定する耐久試験条件に
てドラム走行させ、ショルダー部における最外層ベルト
表面の温度を測定し、比較例１のタイヤ温度を１００と
して指数表示したものであり、数値が小さいほど発熱は
低く、高速耐久性が良好である。 結果は表５及び表６に纏めて示す。表中「実−」は実施
例、「比−」は比較例を示すものである。Next, these cap and base rubber compositions were combined to prepare a 1000 R 2014 PR radial tire by a conventional method, and the performance was evaluated by the following method. Abrasion resistance: After running 100,000 km on a highway, the running distance per wear millimeter of the tread groove of the rear mounted tire was obtained, and indexed with the value of the conventional cap / base structure tire of Comparative Example 1 as 100. The larger the number, the better. Uneven wear resistance: After running 100,000 km on a highway, the average height of crown ribs and shoulder rib heights of front mounted tires were measured, and running per millimeter of shoulder drop wear was measured. The distance (the distance traveled until a step of 1 mm occurs) was obtained, and the tire of Comparative Example 1 was indexed to 100, and the larger the value, the better. Exothermicity: The drum was run under the durability test conditions specified in FMVSS 119, the temperature of the outermost belt surface at the shoulder portion was measured, and the tire temperature of Comparative Example 1 was expressed as 100, and the smaller the value, the lower the value. Heat generation is low and high speed durability is good. The results are summarized in Tables 5 and 6. In the table, "actual-" indicates an example, and "ratio-" indicates a comparative example.
【００２２】表５及び表６から判るように、前記のごと
き本発明に係わる構成要件を全て満足する２層構造トレ
ッドを備えたタイヤ（実施例１〜１３）は、比較例１の
タイヤに比して、いずれも耐摩耗性と耐偏摩耗性が大で
あるにも拘らず、発熱温度が同等かそれ以下であって良
好な高速耐久性を具備している。As can be seen from Tables 5 and 6, the tires (Examples 1 to 13) provided with the two-layered tread satisfying all the constitutional requirements according to the present invention as compared with the tire of Comparative Example 1 In addition, both of them have high wear resistance and uneven wear resistance, but have a high heat generation temperature equal to or lower than that and have excellent high-speed durability.
【００２３】更に詳細に説明すると、比較例１はキャッ
プにＳＡＦカーボンブラックを含有する天然ゴム組成物
を配した従来型キャップ／ベース構造のタイヤであり、
これを特性評価用のコントロールタイヤとした。比較例
２は、比較例１のキャップゴムに汎用タイプのシスＢＲ
（ＢＲ０２）をブレンドしたものである。この場合、耐
摩耗性は改良されるが、キャップゴムの剛性が低下して
発熱が上昇し、肩落ち摩耗が生じ易くなる。そこで、比
較例２におけるキャップゴムの補強性を高めて剛性の低
下を抑え、かつベースゴムを厚くして発熱の上昇を抑制
しようとしたところ、比較例３に示すように、B-Ｍ300
が 11.5 MPa と小さいので逆に発熱が高くなり、肩落ち
摩耗が大きくなった。しかして、比較例４において、こ
のベースゴムのB-Ｍ300 を 17.5 MPa に高めたところ、
発熱性と耐偏摩耗性は比較例１のコントロールタイヤ並
みに回復したが、汎用タイプのシスＢＲ（ＢＲ０２）を
配合したことによる耐摩耗性向上効果が半減するという
結果が得られた。Explaining in more detail, Comparative Example 1 is a tire having a conventional cap / base structure in which a natural rubber composition containing SAF carbon black is arranged in a cap,
This was used as a control tire for characteristic evaluation. Comparative Example 2 is a general-purpose type cis BR in addition to the cap rubber of Comparative Example 1.
It is a blend of (BR02). In this case, the wear resistance is improved, but the rigidity of the cap rubber is lowered, the heat generation is increased, and the shoulder wear is likely to occur. Therefore, when the reinforcement of the cap rubber in Comparative Example 2 was increased to suppress the decrease in rigidity and the base rubber was made thicker to suppress an increase in heat generation, as shown in Comparative Example 3, the B-M300
Since it is as small as 11.5 MPa, on the contrary, the heat generation increases and shoulder drop wear increases. Then, in Comparative Example 4, when the B-M300 of this base rubber was increased to 17.5 MPa,
The heat generation property and the uneven wear resistance were restored to the same level as those of the control tire of Comparative Example 1, but the result was obtained that the effect of improving the wear resistance by half by adding the general-purpose type cis BR (BR02) was halved.
【００２４】実施例１〜５は、比較例４におけるＢＲ０
２の代わりに本発明に係わる改良シスＢＲ（表１のＢＲ
−Ａ〜ＢＲ−Ｅ）を使用すると共に、ＳＡＦより粒子径
が小さいカーボンブラック（表２のＣ−３）を配合して
キャップゴムを構成したものである。このように本発明
の構成要件が満たされた場合には、耐摩耗性、耐偏摩耗
性並びにタイヤ発熱性において全てがバランス良く改善
される。ところが、比較例５〜９に示すように、天然ゴ
ムにブレンドする改質−シスＢＲのマクロ構造に関する
要件（Ｍｗ、Ｍｗ／Ｍｎ及びη）の一つでも欠けた場合
には、発熱温度が上昇し、耐摩耗性向上効果も低下す
る。In Examples 1 to 5, BR0 in Comparative Example 4 was used.
Instead of 2, the improved cis BR according to the present invention (BR in Table 1
-A to BR-E) and carbon black having a smaller particle size than SAF (C-3 in Table 2) is blended to form a cap rubber. When the constituent requirements of the present invention are satisfied in this way, the wear resistance, uneven wear resistance, and tire heat generation are all improved in a well-balanced manner. However, as shown in Comparative Examples 5 to 9, when any of the requirements (Mw, Mw / Mn, and η) regarding the macrostructure of the modified-cis BR blended with the natural rubber is lacking, the exothermic temperature rises. However, the effect of improving wear resistance also decreases.
【００２５】比較例１０は、改質−シスＢＲ（ＢＲ−
Ｃ）のブレンド比率が低すぎるため耐摩耗姓の伸びが小
さい。また、比較例１１のように、改質−シスＢＲのブ
レンド比率が高すぎると発熱が高くなり、偏摩耗が起こ
り易くなる。比較例１２〜１３は、ベースゴムのモジュ
ラスが低いので発熱性と耐偏摩耗性がともに悪くなる。
また、モジュラスが１６MPa 以上のベースゴムでも、Ｔ
B ／ＴA 比が０．２５未満の時（比較例１４）は同様に
発熱性と耐偏摩耗性が悪い。逆にＴB ／ＴA 比が０．４
０を越える場合（比較例１５）には、低発熱、耐偏摩耗
効果は得られるが、耐摩耗性向上効果が小さく、ＢＲ０
２をブレンドした場合（比較例２）と同程度の耐摩耗効
果しか得られていない。Comparative Example 10 is modified-cis BR (BR-
Since the blending ratio of C) is too low, the abrasion resistance is small. Further, as in Comparative Example 11, if the blending ratio of modified-cis BR is too high, heat generation is increased and uneven wear is likely to occur. In Comparative Examples 12 to 13, since the modulus of the base rubber is low, both heat generation and uneven wear resistance are poor.
Even if the base rubber has a modulus of 16 MPa or more,
When B / T A ratio is less than 0.25 (Comparative Example 14) is poor exothermic and uneven wear resistance as well. Conversely, the T B / T A ratio is 0.4
When it exceeds 0 (Comparative Example 15), low heat generation and uneven wear resistance are obtained, but the effect of improving wear resistance is small and BR0
Only the same abrasion resistance effect as when blending 2 (Comparative Example 2) was obtained.
【００２６】比較例１６は、キャップゴムに使用するカ
ーボンブラックの CTAB が低すぎるため耐摩耗性向上効
果が乏しく、また、比較例７のように、該 CTAB が高す
ぎると耐摩耗性と耐偏摩耗性は著しく改良されるが、タ
イヤの発熱が大きくなる。一方、カーボンブラックの C
TAB が所定の範囲にある場合でも、比較例１８のよう
に、配合量が少ないと偏摩耗が生じ易くなり、逆に多す
ぎるとタイヤの発熱温度が上昇するので好ましくない
（比較例１９）。In Comparative Example 16, the CTAB of the carbon black used for the cap rubber is too low, so that the effect of improving the wear resistance is poor, and as in Comparative Example 7, when the CTAB is too high, the wear resistance and the uneven wear resistance are deteriorated. Although the wear resistance is remarkably improved, the heat generation of the tire increases. On the other hand, carbon black C
Even if TAB is within the predetermined range, uneven wear is likely to occur when the compounding amount is small as in Comparative Example 18, and conversely, when it is too large, the heat generation temperature of the tire rises, which is not preferable (Comparative Example 19).
【００２７】[0027]
【発明の効果】以上の結果からも解るように、本発明に
おいては、特定なマクロ構造を有する改質−シスＢＲと
粒子径の小さいカーボンブラックの所定量を含有するゴ
ム組成物からなるキャップゴムに、３００％引張応力を
高くしたベースゴムを組み合わせ、かつトレッド全体の
厚さに対するベースゴムの厚さを従来より大きく設定し
てキャップ／ベース２層構造トレッドを構成したので、
従来型の同種タイヤに比して、耐摩耗性及び耐偏摩耗性
に優れ、しかもこれら特性の向上と背反的関係にあった
発熱温度の上昇が解消され、少なくとも現状レベル以上
の高速耐久性を備えたトラック・バス用ラジアルタイヤ
を得ることができる。As can be seen from the above results, in the present invention, a cap rubber comprising a modified-cis BR having a specific macro structure and a rubber composition containing a predetermined amount of carbon black having a small particle size. In addition, a cap / base two-layer structure tread was constructed by combining a base rubber having a high tensile stress of 300% and setting the thickness of the base rubber with respect to the total thickness of the tread to be larger than before.
Compared with conventional tires of the same type, it is superior in wear resistance and uneven wear resistance, and the rise in heat generation temperature, which is in a trade-off relationship with the improvement of these characteristics, is eliminated, and high-speed durability at least above the current level is eliminated. It is possible to obtain the provided radial tires for trucks and buses.
Claims (2)
２層構造よりなるトラック・バス用ラジアルタイヤにお
いて、該キャップゴムとして、天然ゴムまたは天然ゴム
と合成ポリイソプレンゴムとのブレンドゴム８５〜５０
重量部と、重量平均分子量（Ｍｗ) が５０×１０4 〜７
５×１０4 の範囲にあり、該重量平均分子量（Ｍｗ) と
数平均分子量（Ｍｎ) との比で示される分子量分布（Ｍ
ｗ／Ｍｎ）が１．５〜３．０の範囲にあり、かつ２３℃
のトルエン溶液中の固有粘度［η］が９０以上であるシ
ス-1.4- ポリプタジエンゴム１５〜５０重量部とよりな
るゴム分１００重量部に対し、セチルトリメチルアンモ
ニウムブロマイド吸着比表面積（CTAB) が１３５〜１６
０ m2 /gの範囲にあるカーボンブラックを４５〜６５重
量部配合してなるゴム組成物を用い、また、該ベースゴ
ムとして３００％引張応力（B-Ｍ300 ）が１６ Mpa以上
のゴム組成物を用いると共に、ベースゴムの厚さ
（ＴB ）のトレッドゴムの全厚さ（ＴA ) に対する比
（ＴB ／ＴA ）を０．２５〜０．４０の範囲に設定して
なることを特徴とするトラック・バス用ラジアルタイ
ヤ。1. A radial tire for trucks and buses, wherein the tread has a two-layer structure of a cap rubber and a base rubber, and as the cap rubber, natural rubber or a blend rubber 85 to 50 of a natural rubber and a synthetic polyisoprene rubber is used.
Parts by weight and weight average molecular weight (Mw) are 50 × 10 4 to 7
The molecular weight distribution (Mw) represented by the ratio of the weight average molecular weight (Mw) and the number average molecular weight (Mn) is in the range of 5 × 10 4.
w / Mn) is in the range of 1.5 to 3.0 and is 23 ° C.
Of 100 parts by weight of a rubber component consisting of 15 to 50 parts by weight of cis-1.4-polyptadiene rubber having an intrinsic viscosity [η] of 90 or more in a toluene solution, the cetyltrimethylammonium bromide adsorption specific surface area (CTAB) is 135-16
A rubber composition containing 45 to 65 parts by weight of carbon black in the range of 0 m 2 / g is used, and the base rubber has a 300% tensile stress (B-M300) of 16 Mpa or more. And the ratio (T B / T A ) of the thickness (T B ) of the base rubber to the total thickness (T A ) of the tread rubber is set in the range of 0.25 to 0.40. A characteristic radial tire for trucks and buses.
然ゴム１００重量部当たりセチルトリメチルアンモニウ
ムブロマイド吸着比表面積（CTAB) が１００〜１３０ m
2 /gの範囲にあるカーボンブラックを３５〜５０重量部
配合してなるものである請求項１記載のトラック・バス
用ラジアルタイヤ。2. The rubber composition constituting the base rubber has a cetyltrimethylammonium bromide adsorption specific surface area (CTAB) of 100 to 130 m per 100 parts by weight of natural rubber.
The radial tire for trucks and buses according to claim 1, wherein 35 to 50 parts by weight of carbon black in a range of 2 / g is blended.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP26853793A JP3398434B2 (en) | 1993-10-27 | 1993-10-27 | Radial tires for trucks and buses |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP26853793A JP3398434B2 (en) | 1993-10-27 | 1993-10-27 | Radial tires for trucks and buses |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH07118443A true JPH07118443A (en) | 1995-05-09 |
| JP3398434B2 JP3398434B2 (en) | 2003-04-21 |
Family
ID=17459905
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP26853793A Expired - Fee Related JP3398434B2 (en) | 1993-10-27 | 1993-10-27 | Radial tires for trucks and buses |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP3398434B2 (en) |
Cited By (12)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO1999065980A1 (en) * | 1998-06-15 | 1999-12-23 | Nippon Zeon Co., Ltd. | Conjugated diene rubber composition for tire use and tire |
| KR20020082016A (en) * | 2001-04-23 | 2002-10-30 | 금호산업 주식회사 | Tread rubber composition for truck and bus |
| US6642091B1 (en) | 1999-07-15 | 2003-11-04 | Nec Corporation | Thin-film semiconductor device and apparatus for fabricating thin-film semiconductor device |
| US6861614B1 (en) | 1999-07-08 | 2005-03-01 | Nec Corporation | S system for the formation of a silicon thin film and a semiconductor-insulating film interface |
| US6863733B1 (en) | 1999-07-15 | 2005-03-08 | Nec Corporation | Apparatus for fabricating thin-film semiconductor device |
| JP2005139396A (en) * | 2003-11-10 | 2005-06-02 | Sumitomo Rubber Ind Ltd | Rubber composition |
| US6989300B1 (en) | 1999-07-13 | 2006-01-24 | Nec Corporation | Method for forming semiconductor films at desired positions on a substrate |
| US7049184B2 (en) | 2003-05-09 | 2006-05-23 | Nec Corporation | Semiconductor thin film, thin film transistor, method for manufacturing same, and manufacturing equipment of semiconductor thin film |
| JP2007031523A (en) * | 2005-07-25 | 2007-02-08 | Toyo Tire & Rubber Co Ltd | Rubber composition for tire tread and pneumatic radial tire for truck/bus |
| US7799725B2 (en) | 2004-11-01 | 2010-09-21 | Ube Industries, Ltd. | Catalyst for polymerization of conjugated diene and method of polymerization conjugated diene using the catalyst, rubber composition for tires, and rubber composition for golf balls |
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| JP2012031307A (en) * | 2010-07-30 | 2012-02-16 | Yokohama Rubber Co Ltd:The | Rubber composition for tire tread |
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1993
- 1993-10-27 JP JP26853793A patent/JP3398434B2/en not_active Expired - Fee Related
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| WO1999065980A1 (en) * | 1998-06-15 | 1999-12-23 | Nippon Zeon Co., Ltd. | Conjugated diene rubber composition for tire use and tire |
| US6861614B1 (en) | 1999-07-08 | 2005-03-01 | Nec Corporation | S system for the formation of a silicon thin film and a semiconductor-insulating film interface |
| US7312418B2 (en) | 1999-07-08 | 2007-12-25 | Nec Corporation | Semiconductor thin film forming system |
| US6989300B1 (en) | 1999-07-13 | 2006-01-24 | Nec Corporation | Method for forming semiconductor films at desired positions on a substrate |
| US6642091B1 (en) | 1999-07-15 | 2003-11-04 | Nec Corporation | Thin-film semiconductor device and apparatus for fabricating thin-film semiconductor device |
| US6863733B1 (en) | 1999-07-15 | 2005-03-08 | Nec Corporation | Apparatus for fabricating thin-film semiconductor device |
| KR20020082016A (en) * | 2001-04-23 | 2002-10-30 | 금호산업 주식회사 | Tread rubber composition for truck and bus |
| US7049184B2 (en) | 2003-05-09 | 2006-05-23 | Nec Corporation | Semiconductor thin film, thin film transistor, method for manufacturing same, and manufacturing equipment of semiconductor thin film |
| US8377805B2 (en) | 2003-05-09 | 2013-02-19 | Getner Foundation Llc | Semiconductor thin film, thin film transistor, method for manufacturing same, and manufacturing equipment of semiconductor thin film |
| US7635894B2 (en) | 2003-05-09 | 2009-12-22 | Nec Corporation | Semiconductor thin film, thin film transistor, method for manufacturing same, and manufacturing equipment of semiconductor thin film |
| US8118937B2 (en) | 2003-05-09 | 2012-02-21 | Getner Foundation Llc | Semiconductor thin film, thin film transistor, method for manufacturing same, and manufacturing equipment of semiconductor thin film |
| JP2005139396A (en) * | 2003-11-10 | 2005-06-02 | Sumitomo Rubber Ind Ltd | Rubber composition |
| EP2230262A1 (en) | 2004-11-01 | 2010-09-22 | Ube Industries, Ltd. | Rubber composition for tire |
| US8084565B2 (en) | 2004-11-01 | 2011-12-27 | Ube Industries, Ltd. | Catalyst for polymerization of conjugated diene and method of polymerizing conjugated diene using the catalyst, rubber composition for tires, and rubber composition for golf balls |
| US7799725B2 (en) | 2004-11-01 | 2010-09-21 | Ube Industries, Ltd. | Catalyst for polymerization of conjugated diene and method of polymerization conjugated diene using the catalyst, rubber composition for tires, and rubber composition for golf balls |
| JP2007031523A (en) * | 2005-07-25 | 2007-02-08 | Toyo Tire & Rubber Co Ltd | Rubber composition for tire tread and pneumatic radial tire for truck/bus |
| US7851537B2 (en) | 2006-01-16 | 2010-12-14 | Ube Industries, Ltd. | Rubber composition for tire and tire |
| JP2012031307A (en) * | 2010-07-30 | 2012-02-16 | Yokohama Rubber Co Ltd:The | Rubber composition for tire tread |
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