JPH09254606A - Pneumatic tire for heavy load - Google Patents

Abstract

PROBLEM TO BE SOLVED: To attain compatibility between abrasion resistance and destruction resistance so as to improve the external appearance of a rough road, by using as a tread rubber, a rubber composition prepared by compounding a specific carbon black and a specific polyethylene with a rubber compound comprising specific blended NR and BR. SOLUTION: As a tread rubber for a pneumatic tire for a heavy load, a rubber compound is used, which is prepared by compounding a carbon black of 40 to 60phr having N2 SA of 70m<2> /g or more and a DPB oil absorbing amount of 90ml/100g or more, and polyethylene of 5 to 20phr having a melting point of 120 deg.C or more and a melt flow rate of 20(g/10min.) or below, with 100 of a rubber compound comprising blended NR of 95 to 60phr and BR of 5 to 40phr. Hereby, the external appearance of a rough road can be improved, and also BR can be compounded with the pattern of a Lug system, and abrasion resistance and destruction resistance can be improved.

Description

【発明の詳細な説明】Detailed Description of the Invention

【０００１】[0001]

【発明の属する技術分野】耐摩耗性と抗破壊性を両立さ
せ、悪路外観性を改良した重荷重用の空気入りタイヤに
関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heavy-duty pneumatic tire having both wear resistance and anti-destructiveness and improved appearance on rough roads.

【０００２】[0002]

【従来の技術】タイヤの耐摩耗性を向上させる技術とし
て、従来は １．ＮＲにＢＲをブレンドする。 ２．小粒子径のカ−ボンブラックを用い、更に充填量を
高くする。 等の方法が知られている。しかしながら、近年の環境問
題に絡み、転がり抵抗が小さく燃費性の良いことも、重
要な特性の一つとなりつつあるが、この観点からする
と、上記２の小粒子径、高充填カ−ボンブラックは、配
合物の内部ロスを増大させることとなり、得策ではな
い。従って、上記１のＢＲをブレンドすることによっ
て、耐摩耗性を向上させることが現在の情勢下では一般
的である。2. Description of the Related Art Conventional techniques for improving the wear resistance of tires are as follows. Blend NR with BR. 2. Carbon black with a small particle size is used, and the filling amount is further increased. And other methods are known. However, in view of environmental problems in recent years, low rolling resistance and good fuel economy are becoming one of the important characteristics. From this viewpoint, the above-mentioned small particle size and high filling carbon black are However, this increases the internal loss of the compound, which is not a good idea. Therefore, it is common under the present circumstances to improve the wear resistance by blending the BR of 1 above.

【０００３】一方、ＢＲブレンドとすることで、耐摩耗
性は改良されるが、逆に天然ゴム比率が減少する為、抗
破壊性が低下し、特に悪路走行でのトレッド外観が悪化
することは、避けられない。この傾向は特にサイブの多
いパタ−ンやブロックパタ−ンにおいて顕著である。On the other hand, when the BR blend is used, the abrasion resistance is improved, but on the contrary, the natural rubber ratio is decreased, so that the anti-destructive property is deteriorated and the tread appearance is deteriorated especially on a bad road. Is inevitable. This tendency is particularly noticeable in patterns with many sives and block patterns.

【０００４】また、ＵＳＰ第４，６７５，３４９号特許
明細書、ＵＳＰ第５，３４１，８６３号特許明細書に関
連技術が記載されているが、ＵＳＰ第４，６７５，３４
９号特許明細書に記載のものは、配合に際して微細なポ
リエチレン粒子を添加せざるを得ず、配合の取り扱いが
困難であると同時に、配合物において、ポリエチレン粒
子が凝集して配合物の物性を低下させる恐れがある。Further, although related arts are described in USP 4,675,349 and USP 5,341,863, USP 4,675,34.
The thing described in the patent specification of 9 has to add fine polyethylene particles at the time of compounding, and it is difficult to handle the compounding, and at the same time, in the compounding, the polyethylene particles aggregate to improve the physical properties of the compounding. It may decrease.

【０００５】そして、ＵＳＰ第５，３４１，８６３号特
許明細書に記載のものは、ＬＤＰＥを使用しているが、
高温での配合物の変化が著しく、ゴム組成物として、特
にタイヤ用ゴム組成物としては使用が困難と言わざるを
得ない。And, while the one described in USP No. 5,341,863 uses LDPE,
It can be said that it is difficult to use as a rubber composition, especially as a rubber composition for tires, because the composition changes remarkably at high temperatures.

【０００６】[0006]

【発明が解決しようとする課題】重荷重用の空気入りタ
イヤにおいて、耐摩耗性と抗破壊性を両立させ、悪路外
観性を改良することを目的とする。SUMMARY OF THE INVENTION It is an object of a pneumatic tire for heavy loads to have both wear resistance and anti-destructiveness and to improve the appearance of rough roads.

【０００７】[0007]

【課題を解決するための手段】そこで、本発明者は上記
目的を達成するため、鋭意検討を重ねた結果、下記の様
な条件を満たすゴム組成物を、重荷重用の空気入りタイ
ヤのトレッドゴムとして使用することによって、達成さ
れることが判った。In order to achieve the above object, the inventors of the present invention have conducted extensive studies, and as a result, have found that a rubber composition satisfying the following conditions is used as a tread rubber for a heavy-duty pneumatic tire. Has been found to be achieved.

【０００８】ＮＲ９５〜６０，ＢＲ５〜４０ｐｈｒから
なるゴム成分１００に対して、Ｎ₂ＳＡが７０ｍ²／ｇ以
上でＤＢＰ吸油量９０ｍｌ／１００ｇ以上のカ−ボンブ
ラック４０〜６０ｐｈｒと、融点が１２０℃以上、メル
トフロ−レ−トが２０（ｇ／１０ｍｉｎ．）以下のポリ
エチレンを５〜２０ｐｈｒとを、配合して成るゴム組成
物。Carbon rubber 40 to 60 phr with N ₂ SA of 70 m ² / g or more and DBP oil absorption of 90 ml / 100 g or more, and a melting point of 120 ° C. for 100 rubber components consisting of NR 95 to 60 and BR 5 to 40 phr. A rubber composition obtained by blending 5 to 20 phr of polyethylene having a melt flow rate of 20 (g / 10 min.) Or less.

【０００９】上記各成分の作用、数値については、以下
の様な理由による。 １，ＢＲを５〜４０ｐｈｒブレンドする点。 ＢＲをブレンドすることにより、配合ゴムのガラス転移
点（Ｔｇ）が低温化するため、ロス特性が低下し、路面
との摩擦力が小さくなり、摩耗入力が低減される。した
がって、耐摩耗性が向上する。The action and numerical values of the above components are as follows. The point where 1 and BR are blended for 5 to 40 phr. By blending BR, the glass transition point (Tg) of the compounded rubber is lowered, so that the loss characteristics are lowered, the frictional force with the road surface is reduced, and the wear input is reduced. Therefore, the wear resistance is improved.

【００１０】一方、天然ゴム成分の減少によって、天然
ゴムの伸張結晶性が小さくなり、特に、タイヤ走行時を
想定した高温条件下での抗破壊性が低下する。On the other hand, due to the decrease in the natural rubber component, the stretch crystallinity of the natural rubber becomes small, and in particular, the anti-destructive property under a high temperature condition assuming running of the tire is lowered.

【００１１】従って、ＢＲのブレンド量が一つのポイン
トであるが、ＢＲが５ｐｈｒ以下では、耐摩耗性向上の
効果は少なく、４０ｐｈｒ以上では、耐摩耗性向上に較
べ、抗破壊性の低下が著しい。なお、ＢＲは高ｃｉｓＢ
Ｒ、すなわちｃｉｓ含量９０％以上のものを用いること
を前提とする。Therefore, one point is the blending amount of BR. When the BR is 5 phr or less, the effect of improving the wear resistance is small, and when the BR is 40 phr or more, the deterioration of the fracture resistance is remarkable as compared with the improvement of the wear resistance. . In addition, BR is high cisB
It is premised that R, that is, a cis content of 90% or more is used.

【００１２】２，カ−ボンブラックについては、ＨＡＦ
級より大粒径（Ｎ₂ＳＡ＜８０）のものを４０ｐｈｒ以
下では、重荷重用トレッドゴムとして、耐摩耗性を確保
できない。また、６０ｐｈｒ以上では混練効率が悪化
し、分散不良による抗破壊性の低下をきたす。2. For carbon black, HAF
If the particle size is larger than the grade and has a particle size (N ₂ SA <80) of 40 phr or less, the wear resistance cannot be secured as a heavy load tread rubber. On the other hand, if it is more than 60 phr, the kneading efficiency will be deteriorated and the anti-destructive property will be lowered due to poor dispersion.

【００１３】３，ポリエチレンは、通常使用領域では安
定な結晶状態なので、耐摩耗維持にするに充分な硬度を
保持し、異物乗り上げの様な、大歪入力条件下では、結
晶領域の破壊による内部ロスが破壊エネルギ−を吸収す
るため、破壊限界が向上する。この傾向は、特にＢＲブ
レンド系と組み合わせると、従来技術では得られなかっ
た耐摩耗と抗破壊性の両立が実現可能である。3. Since polyethylene is a stable crystalline state in the normal use region, it retains sufficient hardness to maintain wear resistance, and under a large strain input condition such as foreign matter riding on, the inside of the crystal region is destroyed by destruction. Since the loss absorbs the breaking energy, the breaking limit is improved. This tendency, especially when combined with a BR blend system, makes it possible to achieve both wear resistance and fracture resistance, which were not obtained in the prior art.

【００１４】ポリエチレンは５ｐｈｒ以下では抗破壊性
の向上は望めず、２０ｐｈｒ以上では抗破壊性の向上に
較べ耐摩耗性の低下が著しい。望ましくは１０ｐｈｒか
ら１５ｐｈｒである。When polyethylene is less than 5 phr, improvement in anti-destructive property cannot be expected, and when it is more than 20 phr, abrasion resistance is remarkably lowered as compared with improvement in anti-destructive property. Desirably it is from 10 phr to 15 phr.

【００１５】４，接地圧の規定 タイヤと路面の接地圧が４ｋｇ／ｃｍ² 以下では突起乗
り上げ時の入力が小さいため抗破壊性が低下しても悪路
外観性は大きな問題とは成らない。したがって、４ｋｇ
／ｃｍ²以上の使用域で本発明は効果的である。。4. Regulation of ground contact pressure When the ground contact pressure between the tire and the road surface is 4 kg / cm ² or less, the input when riding on the protrusions is small, so that the deterioration of the fracture resistance does not cause a serious problem on the appearance of the rough road. Therefore, 4 kg
The present invention is effective in the use range of / cm ² or more. .

【００１６】[0016]

【発明の実施の形態】以下、実施例及び比較例によって
この発明を詳細に説明するが、本発明はこれらの実施例
に限定されるものではない。BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail with reference to Examples and Comparative Examples, but the present invention is not limited to these Examples.

【表１】 [Table 1]

【００１７】なお、上記各種物性試験は以下の方法に拠
った。 １、１００℃Ｅｂ（抗破壊性試験） 抗破壊性（悪路外観性）の測定方法として、走行時温度
を想定し１００℃での破断伸びを用いた。（試験法はＪ
ＩＳ）The above-mentioned various physical property tests were based on the following methods. 1, 100 ° C. Eb (Anti-destructive test) As a method for measuring the anti-destructive property (appearance on bad road), the breaking elongation at 100 ° C. was used assuming the running temperature. (Test method is J
IS)

【００１８】２、耐摩耗指数 耐摩耗指数は、試作タイヤを実地で評価。８万ｋｍ走行
後のミリ当たり走行距離で評価し、耐摩耗性の良いもの
程、指数は大きい。（サイズ…１１Ｒ２２．５）2. Abrasion resistance index The abrasion resistance index was obtained by actually evaluating a trial tire. Evaluated by the traveling distance per millimeter after traveling 80,000 km, the better the abrasion resistance, the larger the index. (Size ... 11R22.5)

【００１９】３、配合内容 ＮＲとＢＲとからなるゴム成分１００（ＮＲは変量、Ｂ
Ｒは表１の量）に対して、 ＳＡＦ級カ−ボンブラック５０（Ｎ₂ＳＡ＝８０ ＤＢ
Ｐ吸油量１４０） ステアリン酸 ３ 老化防止剤 １．５ 亜鉛華 ３．５ 加硫促進剤 １．０ 硫黄 １．５ を配合した。3. Content of compounding Rubber component 100 consisting of NR and BR (NR is a variable, B
R is the amount in Table 1), SAF carbon black 50 (N ₂ SA = 80 DB)
P oil absorption 140) Stearic acid 3 Anti-aging agent 1.5 Zinc white 3.5 Vulcanization accelerator 1.0 Sulfur 1.5 was compounded.

【００２０】表１からわかるように、実施例はいずれ
も、１００℃Ｅｂ指数及び耐摩耗指数が１００以上であ
るのに対して、比較例では、１００℃Ｅｂが１００以上
のものでは耐摩耗指数が１００以下であり、耐摩耗指数
が１００以上のものでは、１００℃Ｅｂが１００以下と
なっており、いずれか一方が不満足である。すなわち、
本発明のように特定のカ−ボンブラックと、特定のポリ
エチレンを配合した場合のみ、１００℃Ｅｂ及び耐摩耗
指数の両者を満足させることが可能である。As can be seen from Table 1, in each of the examples, the 100 ° C. Eb index and the wear resistance index are 100 or more, whereas in the comparative example, the 100 ° C. Eb index and the wear resistance index are 100 or more. Is 100 or less and the abrasion resistance index is 100 or more, 100 ° C. Eb is 100 or less, and either one is unsatisfactory. That is,
Only when a specific carbon black and a specific polyethylene are blended as in the present invention, it is possible to satisfy both 100 ° C. Eb and abrasion resistance index.

【００２１】[0021]

【発明の効果】本発明により、ＢＲを重荷重用タイヤト
レッドに用いたときの最大の欠点である、悪路外観性を
改良することができ、Ｌｕｇ系のパタ−ン（悪路専用パ
タ−ン）にＢＲ配合が可能となり、著しく摩耗の早い該
使用域でもタイヤ寿命を伸ばすことができる。According to the present invention, it is possible to improve the appearance of a rough road, which is the greatest drawback when the BR is used in a heavy-duty tire tread, and to improve the appearance of a Lug type pattern (a rough road-specific pattern). BR can be added to the rubber composition, and the life of the tire can be extended even in the use area where wear is extremely fast.

Claims (3)

【特許請求の範囲】[Claims] 【請求項１】 天然ゴム９５〜６０，ポリブタジエンゴ
ム５〜４０ｐｈｒからなるゴム成分１００に対して、Ｎ
₂ＳＡが７０ｍ²／ｇ以上でＤＢＰ吸油量９０ｍｌ／１０
０ｇ以上のカ−ボンブラック４０〜６０ｐｈｒと、融点
が１２０℃以上、メルトフロ−レ−トが２０（ｇ／１０
ｍｉｎ．）以下のポリエチレン５〜２０ｐｈｒとを、配
合して成るゴム組成物をトレッドゴムとして使用したこ
とを特徴とする重荷重用空気入りタイヤ。1. A rubber component consisting of natural rubber 95 to 60 and polybutadiene rubber 5 to 40 phr is added to N.
₂ SA 70m ² / g or more, DBP oil absorption 90ml / 10
Carbon black 40 to 60 phr of 0 g or more, melting point of 120 ° C. or more, melt flow rate of 20 (g / 10
min. ) A heavy-duty pneumatic tire, characterized in that a rubber composition obtained by compounding the following polyethylene (5 to 20 phr) is used as a tread rubber. 【請求項２】 接地圧が４ｋｇ／ｃｍ²以上の重荷重域
で使用される請求項１に記載の重荷重用空気入りタイ
ヤ。2. The pneumatic tire for heavy loads according to claim 1, which is used in a heavy load range where the ground contact pressure is 4 kg / cm ² or more. 【請求項３】 ポリエチレンの配合が１０〜１５ｐｈｒ
である請求項１に記載の重荷重域用空気入りタイヤ。3. Polyethylene blend of 10 to 15 phr
The pneumatic tire for heavy load areas according to claim 1.