JP2564760B2 - Pneumatic tire - Google Patents
Pneumatic tireInfo
- Publication number
- JP2564760B2 JP2564760B2 JP5264276A JP26427693A JP2564760B2 JP 2564760 B2 JP2564760 B2 JP 2564760B2 JP 5264276 A JP5264276 A JP 5264276A JP 26427693 A JP26427693 A JP 26427693A JP 2564760 B2 JP2564760 B2 JP 2564760B2
- Authority
- JP
- Japan
- Prior art keywords
- rubber
- tread
- foamed rubber
- ice
- performance
- 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.)
- Expired - Lifetime
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- Tires In General (AREA)
Description
【０００１】[0001]
【産業上の利用分野】本発明は空気入りタイヤ、詳しく
は、夏季の操縦性能および発熱耐久性を損なうことな
く、耐摩耗性が実用に耐え、氷雪路面上における駆動
性、制動性および操縦性を改良した空気入りタイヤに関
するものである。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pneumatic tire, and more specifically, to a wear resistance that can be practically used without impairing the driving performance and heat resistance in summer, and the drivability, braking performance and drivability on a snowy and snowy road surface. The present invention relates to an improved pneumatic tire.
【０００２】[0002]
【従来の技術】従来、氷雪路面上を走行する際の駆動
性、制動性および操縦性（以下、単に、「氷雪性能」と
もいう。）を確保するために、スパイクピンをトレッド
表部に打ち込んだスパイクタイヤ或いはスパイクピンを
用いない、所謂、スタッドレスタイヤ等の空気入りタイ
ヤが知られている。2. Description of the Related Art Conventionally, a spike pin has been driven into a tread surface in order to secure driveability, braking performance and maneuverability (hereinafter, simply referred to as "ice and snow performance") when traveling on an ice and snow road surface. There are known pneumatic tires such as so-called studless tires that do not use spike tires or spike pins.
【０００３】[0003]
【発明が解決しようとする課題】しかしながら、スパイ
クタイヤの場合には、スパイクピンの摩耗や道路の摩耗
によるこれらの微粉末が飛散する粉塵公害およびスパイ
クピンによる道路の損傷が起こり、大きな社会問題にな
っている。これらの問題に対処するため、スパイクピン
の突出し量、打ち込み数の規制およびスパイクピンの材
質等の検討がなされているが、前記社会問題の根本的な
解決にはなっていない。However, in the case of spiked tires, dust pollution caused by the wear of spike pins and road wear resulting from the scattering of these fine powders and road damage due to spike pins occur, which is a major social problem. Has become. In order to deal with these problems, the amount of protrusion of the spike pin, the regulation of the number of driving, and the material of the spike pin have been studied, but they have not been a fundamental solution to the social problem.
【０００４】一方、スパイクピンを用いない、所謂、ス
タッドレスタイヤにおいて、タイヤトレッドの模様、ト
レッドゴム質の検討がなされているが、スパイクタイヤ
と同等の氷雪性能は発揮できないという問題点がある。
特に、トレッドゴム質については、低温時のゴム弾性を
確保するために、ガラス転移点の低いポリマーを用い、
且つ、低温時の路面との摩擦係数を確保するために、低
融点の軟化剤を用いることも検討されているが、氷雪性
能が十分でないという問題点がある。On the other hand, in so-called studless tires that do not use spike pins, the tire tread pattern and tread rubber quality have been studied, but there is a problem that the same snow and snow performance as spike tires cannot be exhibited.
In particular, regarding the tread rubber, in order to ensure rubber elasticity at low temperatures, use a polymer with a low glass transition point,
Further, in order to secure a coefficient of friction with a road surface at a low temperature, use of a softening agent having a low melting point has been studied, but there is a problem that ice and snow performance is not sufficient.
【０００５】また、独立気泡を有するゴムをトレッドに
用いたタイヤは、特公昭４０−４６４１号公報、米国特
許第４２４９５８８号明細書および特公昭５６−１５４
３０４号公報等において提案されている。しかしなが
ら、特公昭４０−４６４１号公報においては、トレッド
にヒステリシスロスの大きい合成ゴム、例えばハイスチ
レンゴムを使用しているので、ゴムのガラス転移温度を
上昇させ、低温におけるゴムの硬度が増加し、従って、
氷雪性能を確保する上で好ましくない。また、米国特許
第４２４９５８８号明細書においては、トレッドゴムの
温度２５°Ｃ、圧縮歪５０％での圧縮特性（応力）が１
〜８００ｐｓｉと規定しているが、自動車用空気入りタ
イヤのトレッドゴムとしては、少なくとも４００ｐｓｉ
以上でないと操縦応答性の点で実用的でない。更に、特
開昭５６−１５４３０４号公報においては、発泡ゴムを
用いて無発泡ゴムと同じ硬さを得ることにより軽量タイ
ヤにしているが、これでは氷雪性能を向上させることは
できない。Tires using rubber having closed cells as the tread are disclosed in Japanese Patent Publication No. 40-4641 and US Pat. No. 4,249,588 and Japanese Patent Publication No. 56-154.
No. 304, etc. However, in Japanese Patent Publication No. 40-4641, the synthetic rubber having a large hysteresis loss, such as high styrene rubber, is used for the tread, so that the glass transition temperature of the rubber is increased and the hardness of the rubber at low temperature is increased, Therefore,
It is not preferable in securing ice and snow performance. Further, in the specification of US Pat. No. 4,249,588, the tread rubber has a compression characteristic (stress) of 1 at a temperature of 25 ° C. and a compression strain of 50%.
Although it is specified as ~ 800 psi, the tread rubber for pneumatic tires for automobiles should be at least 400 psi.
Unless it is above, it is not practical in terms of steering response. Furthermore, in JP-A-56-154304, a lightweight tire is obtained by using foamed rubber to obtain the same hardness as unfoamed rubber, but this cannot improve the snow and snow performance.
【０００６】また、トレッドゴムに砂、金鋼砂、カーボ
ランダム、金属粒など粒状体を混入することにより氷雪
路面におけるすべり性を改良することも試みられている
が、粒状体を多量に混入しないとすべり性が改良され
ず、一方、多量に混入すると耐摩耗性が著しく悪化して
しまうという問題点がある。更に、氷上の制動性能を向
上するために、トレッドゴムの硬度を下げることも行わ
れている。即ち、補強剤の減量、ゴムの架橋密度の減
少、オイル軟化剤の増量等が行われているが、補強剤を
減量すると湿潤路面における制動性能が低下し、ゴムの
架橋密度の減少はゴムのヘタリ（永久変形）を発生さ
せ、オイルおよび軟化剤の増量は走行時、長期使用時の
ゴムの硬度変化を大きくする等の問題点がある。Attempts have also been made to improve the slipperiness on ice and snow road surfaces by incorporating particles such as sand, gold steel sand, carborundum, and metal particles into the tread rubber, but do not incorporate large amounts of particles. However, there is a problem in that the slip resistance is not improved, and on the other hand, if a large amount is mixed, the wear resistance is significantly deteriorated. Further, in order to improve braking performance on ice, the hardness of the tread rubber is also reduced. That is, the amount of the reinforcing agent is reduced, the crosslink density of the rubber is reduced, and the amount of the oil softening agent is increased.However, when the amount of the reinforcement agent is reduced, braking performance on a wet road surface is deteriorated, and the decrease in the crosslink density of the rubber is There is a problem in that the increase in the amount of oil and softening agent that causes permanent set (permanent deformation) increases the hardness change of the rubber during running and long-term use.
【０００７】本発明の目的は、上述した従来のスパイク
タイヤ或いはスタッドレスタイヤ等が有する課題を解決
することにあり、タイヤの氷雪性能、耐摩耗性能、操縦
性能および発熱耐久性能を両立させるとともに、タイヤ
の氷上摩擦係数、特に温度０゜Ｃ付近の湿潤伏態にある
氷上の摩擦係数を向上させ実用上の使用に充分耐え得る
空気入りタイヤを提供することにある。An object of the present invention is to solve the problems of the above-mentioned conventional spike tires, studless tires, etc., and to achieve both ice and snow performance, wear resistance performance, steering performance and heat generation durability performance of the tire, and Another object of the present invention is to provide a pneumatic tire capable of improving the friction coefficient on ice, particularly the friction coefficient on ice in a wet state near a temperature of 0 ° C., which can sufficiently withstand practical use.
【０００８】[0008]
【課題を解決するための手段】本発明者らは、上述した
問題を解決するため、種々検討した結果、トレッドのゴ
ム層にガラス転移点の低いポリマーを用い、ゴムの内部
に独立気泡を含有させることによりゴム自体の架橋密度
を減少させることなく、トレッドゴム全体、即ち、ゴム
と泡との複合体全体の硬度を減少させ得ることを見出し
た。また、この際、弾性率の高いゴムを発泡させること
により発泡ガスの軟化作用により適度のトレッドゴムの
硬度を得ることができることを見出した。更に、トレッ
ドゴムに、加硫により独立気泡を形成する発泡剤ととも
に少量の低温軟化剤を併用すると、トレッドの動的弾性
率および内部損失が調節でき、且つ、長期使用時のゴム
の硬度の変化を少なくでき、このために、湿潤氷面での
摩擦係数が増大し、湿潤氷面でのタイヤの制動性、駆動
性、コーナリング性が改良されることを見出した。これ
らの事実をもとに、更に、構造面からも検討を重ねた結
果、本発明に到達した。In order to solve the above-mentioned problems, the inventors of the present invention have made various investigations and as a result, as a result, a polymer having a low glass transition point was used for the rubber layer of the tread, and closed cells were contained inside the rubber. It has been found that by doing so, the hardness of the entire tread rubber, that is, the entire composite of rubber and foam can be reduced without reducing the crosslink density of the rubber itself. Further, at this time, it was found that by foaming rubber having a high elastic modulus, an appropriate hardness of the tread rubber can be obtained by the softening action of the foaming gas. Furthermore, when a small amount of a low temperature softening agent is used together with a foaming agent that forms closed cells by vulcanization in the tread rubber, the dynamic elastic modulus and internal loss of the tread can be adjusted, and the hardness of the rubber changes during long-term use. It was found that the friction coefficient on the wet ice surface is increased, and the braking performance, drivability, and cornering property of the tire on the wet ice surface are improved. Based on these facts, as a result of further studies from the viewpoint of the structure, the present invention has been achieved.
【０００９】ここに、トレッドが含有するゴム成分のう
ちガラス転移温度−６０°Ｃ以下の重合物とは、例えば
天然ゴム、ポリイソプロピレンゴム、ポリプタジエンゴ
ム、ブチルゴム、低スチレン含有のスチレン・ブタジエ
ン共重合ゴムの単独、または、これらの重合物の２種以
上の混合物である。この理由は、これらの重合物を用い
ることによりトレッドは低温においても充分にゴム弾性
を有するからである。ただし、必要に応じ、ゴム成分の
一部にガラス転移温度−６０゜Ｃより高い重合部、例え
ば高スチレン含有のスチレン・ブタジエン共重合ゴムを
含有してもよい。Here, among the rubber components contained in the tread, the polymer having a glass transition temperature of -60 ° C. or lower means, for example, natural rubber, polyisopropylene rubber, polyptadiene rubber, butyl rubber, styrene containing low styrene. It is a butadiene copolymer rubber alone or a mixture of two or more of these polymers. The reason for this is that by using these polymers, the tread has sufficient rubber elasticity even at low temperatures. However, if necessary, a part of the rubber component may contain a polymerized portion having a glass transition temperature higher than −60 ° C., for example, a styrene / butadiene copolymer rubber having a high styrene content.
【００１０】また、発泡ゴム層は、トレッドの全体積の
少なくとも１０％以上の体積を有するのが望ましく、好
ましくは１０〜７０％、更に好ましくは４０〜６０％で
ある。発泡ゴム層をトレッド全体積の少なくとも１０％
以上の体積を有するとしたのは、１０％未満では氷雪性
能の改良効果が少ないためである。また、発泡ゴム層を
トレッドに用いる方法としては、トレッド全体が発泡ゴ
ム層（発泡ゴム層１００％）からなってもよい。The foamed rubber layer desirably has a volume of at least 10% or more of the total volume of the tread, preferably 10 to 70%, more preferably 40 to 60%. At least 10% of the total tread volume of the foam rubber layer
The reason for having the above volume is that if it is less than 10%, the effect of improving the snow and snow performance is small. Further, as a method of using the foamed rubber layer for the tread, the entire tread may be composed of the foamed rubber layer (foamed rubber layer 100%).
【００１１】また、発泡ゴムの発泡率Ｖｓは、次式 Ｖｓ＝｛（ρ０−ρ９）／（ρ１−ρ９）−１｝×１００（％）・・（１） で表され、ρ１は発泡ゴムの密度（ｇ／ｃｍ３） 、ρ
０は発泡ゴムのゴム固相部の密度（ｇ／ｃｍ３）、ρ９
は発泡ゴムの気泡内のガス部の密度（ｇ／Ｃｍ３）であ
る。発泡ゴムはゴム固相部と、ゴム固相部によって形成
される空洞（独立気泡）、即ち、気泡内のガス部とから
構成されている。ガス部の密度ρ９は極めて小さく、ほ
ぼ零に近く、且つ、ゴム固相部の密度ρ１に対して極め
て小さいので、式（１）は、次式 Ｖｓ＝（ρ０／ρ１−１）×１００（％）・・・・・・・・・・・・（２） とほぼ同等となる。発泡率Ｖｓは５〜５０％の範囲が望
ましく、好ましくは５〜３０％である。発泡率Ｖｓを５
〜５０％としたのは、５％未満では、低温時の発泡ゴム
の柔軟性が得られず、また、５０％を超えると、耐摩耗
性能が低下して氷雪路面、湿潤路面以外の乾燥路面での
耐摩耗性が実用的に不十分であるからである。Further, the foaming rate Vs of the foamed rubber is represented by the following formula Vs = {(ρ 0 −ρ 9 ) / (ρ 1 −ρ 9 ) −1} × 100 (%) ·· (1), ρ 1 is the density of foamed rubber (g / cm 3 ), ρ
0 is the density (g / cm 3 ) of the solid phase portion of the foamed rubber, ρ 9
Is the density (g / Cm 3 ) of the gas portion in the bubbles of the foamed rubber. The foamed rubber is composed of a rubber solid portion and a cavity (closed cell) formed by the rubber solid portion, that is, a gas portion in the bubble. Since the density ρ 9 of the gas portion is extremely small and is almost zero and is extremely small with respect to the density ρ 1 of the rubber solid phase portion, the equation (1) is expressed by the following equation Vs = (ρ 0 / ρ 1 −1). ) × 100 (%) ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ (2) is almost the same. The foaming rate Vs is desirably in the range of 5 to 50%, preferably 5 to 30%. Foaming rate Vs is 5
-50% is less than 5%, the flexibility of the foamed rubber at low temperature cannot be obtained, and if it exceeds 50%, the abrasion resistance is deteriorated and the dry road surface other than the icy snow road surface and the wet road surface. This is because the wear resistance at is not practically sufficient.
【００１２】また、発泡ゴムの独立気泡の平均気泡径は
５〜１５０μｍが望ましく、好ましくは１０〜１００μ
ｍである。発泡ゴムの独立気泡の平気気泡径を５〜１５
０μｍとしたのは、５μｍ未満では氷雪性能の改良効果
が少なく、また、平均気泡径が１５０μｍを超えると耐
摩耗性能が大幅に低下し、更に、発泡ゴムの歪み復元力
が低下し、所謂、耐ヘタリ性が低下し、走行時により、
タイヤブロックの変形、サイプの目づまり等を起こし、
雪上性能を低下させる。また、耐カット性も低下しブロ
ック欠けが多くなる。更に、製造時に安定した形状を得
ることが困難であるからである。The average cell diameter of the closed cells of the foamed rubber is preferably 5 to 150 μm, preferably 10 to 100 μm.
m. Closed air bubble diameter of closed cells of foam rubber is 5 to 15
0 μm means that if the thickness is less than 5 μm, the effect of improving the snow and snow performance is small, and if the average bubble diameter exceeds 150 μm, the wear resistance performance is significantly lowered, and further, the strain restoring force of the foamed rubber is lowered, The settling resistance is reduced, and
Deformation of tire blocks, clogging of sipes, etc.
Reduces snow performance. In addition, the cut resistance is reduced and the number of chipped blocks is increased. Furthermore, it is difficult to obtain a stable shape during manufacturing.
【００１３】また、発泡ゴムが気泡直径３０〜１２０μ
ｍの独立気泡を単位面積１ｍｍ２当たり２０個以上を含
有することが望ましく、好ましくは３０個以上である。
ここに、独立気泡を単位面積１ｍｍ２当たり２０個以上
としたのは、２０個未満では氷雪路面に接触するトレッ
ドゴムのゴム表面の独立気泡により生ずる凹凸状態が十
分でなく氷雪性能を十分に発揮できないためである。The foamed rubber has a bubble diameter of 30 to 120 μm.
It is desirable to contain 20 or more, and preferably 30 or more, closed cells of m per unit area of 1 mm 2 .
Here, 20 or more closed cells per unit area of 1 mm 2 are used because if the number is less than 20, the unevenness caused by the closed cells on the rubber surface of the tread rubber that comes into contact with the road surface of ice and snow is not sufficient and the ice and snow performance is sufficiently exhibited. This is because it cannot be done.
【００１４】また、本発明に係る空気入りタイヤのトレ
ッドに用いる発泡ゴムは、通常のゴム配合物に発泡剤を
加えて通常のタイヤ製造方法にしたがって加熱加圧する
際形成される。発泡剤としては、例えば、アゾジカーボ
ンアミド、ジニトロソ・ペンタメチレン−テトラアミ
ン、アゾビスイソプチロニトリル、ベンゼンスルフォニ
ルヒドラジド、高沸点炭化水素化合物の樹脂ミクロカプ
セル等が用いられる。The foamed rubber used for the tread of the pneumatic tire according to the present invention is formed by adding a foaming agent to a usual rubber compound and heating and pressing it according to a usual tire manufacturing method. As the foaming agent, for example, azodicarbonamide, dinitroso pentamethylene-tetraamine, azobisisobutyronitrile, benzenesulfonyl hydrazide, resin microcapsules of a high boiling hydrocarbon compound, and the like are used.
【００１５】また、発泡ゴムがゴム成分１００重量部に
対し、低温軟化剤２〜２０重量部を含有することとした
のは、これにより発泡ゴムの動的弾性率と内部損失との
調節ができ氷上摩擦性能を改良できるからである。低温
軟化剤としては、凝固点が−４０゜Ｃ以下である低温可
塑剤、即ち、ジオクチルアジペート（ＤＯＡ）、ジオク
チルフタレート（ＤＯＰ）、ジオクチルセバケート（Ｄ
ＯＳ）、ジヘプチルフタレート（ＤＨＰ）、ジエチルフ
タレート（ＤＥＰ）、ジオクチルアビレート（ＤＯ
Ｚ）、ジブチルマレエート（ＤＢＭ），トリブチルホス
ヘート（ＴＢＰ）、トリオクチルホスヘート（ＴＯＰ）
等が用いられる。Further, the reason why the foamed rubber contains 2 to 20 parts by weight of the low temperature softening agent based on 100 parts by weight of the rubber component is that the dynamic elastic modulus and the internal loss of the foamed rubber can be adjusted. This is because the friction performance on ice can be improved. As the low temperature softening agent, a low temperature plasticizer having a freezing point of -40 ° C. or lower, that is, dioctyl adipate (DOA), dioctyl phthalate (DOP), dioctyl sebacate (D
OS), diheptyl phthalate (DHP), diethyl phthalate (DEP), dioctyl avilate (DO)
Z), dibutyl maleate (DBM), tributyl phosphate (TBP), trioctyl phosphate (TOP)
Etc. are used.
【００１６】以下、実施例に基づいて、本発明をより詳
細に説明するが、発泡ゴムの性質および試験タイヤによ
るタイヤ性能の試験は下記の方法で行った。The present invention will be described in more detail based on the following examples. The properties of the foamed rubber and the tire performance of the test tires were tested by the following methods.
【００１７】試験法 （１）平均気泡径および発泡率Ｖｓ 発泡ゴムの平均気泡径は、試験タイヤのトレッドの発泡
ゴム層からブロック状の試料を切り出し、その試料断面
の写真を倍率１００〜４００の光学顕微鏡で撮影し、２
００個以上の独立気泡の気泡直径を測定し、算術平均値
として表わした。また、発泡ゴムの発泡率Ｖｓは、ブロ
ック状の前記試料の密度ρ１（ｇ／ｃｍ３）を測定し、
一方、無発泡ゴム（固相ゴム）のトレッドの密度ρ
０（ｇ／ｃｍ３）を測定し、前記式（２）を用いて求め
た。Test Method (1) Average Cell Diameter and Foaming Ratio Vs For the average cell diameter of the foamed rubber, a block-shaped sample was cut out from the foamed rubber layer of the tread of the test tire, and a photograph of a cross section of the sample was taken at a magnification of 100 to 400. Taken with an optical microscope, 2
The bubble diameter of 00 or more independent bubbles was measured and expressed as an arithmetic mean value. The foaming rate Vs of the foamed rubber is obtained by measuring the density ρ 1 (g / cm 3 ) of the block-shaped sample,
On the other hand, the density ρ of the non-foamed rubber (solid phase rubber) tread
0 (g / cm 3 ) was measured, and it was determined using the above formula (2).
【００１８】（２）独立気泡の気泡直径および気泡数 発泡ゴムの独立気泡の気泡直径および気泡数は、試験タ
イヤのトレッドの発泡ゴム層からブロック状の試料を切
り出し、その試料断面の写真を倍率１００〜４００の光
学顕微鏡で撮影し、独立気泡の気泡直径を求める。次い
で、独立気泡の気泡直径が５μｍ以上の気泡数を延べ面
積４ｍｍ２以上にわたって測定し、独立気泡の単位面積
１ｍｍ２当たりの気泡数（個）を計算した。(2) Cell diameter and number of closed cells The closed cell diameter and number of the foamed rubber were determined by cutting out a block-shaped sample from the foamed rubber layer of the tread of the test tire and magnifying a photograph of the cross section of the sample. The image is taken with an optical microscope of 100 to 400 to determine the bubble diameter of the closed bubbles. Next, the number of bubbles having a bubble diameter of 5 μm or more was measured over a total area of 4 mm 2 or more, and the number of bubbles (unit) per unit area 1 mm 2 of the closed bubbles was calculated.
【００１９】（３）発泡ゴムの表面粗さおよび氷上摩擦
係数 発泡ゴムのゴム表面の微小な凹凸を特定化する表面粗さ
として、ＪＩＳ表面粗さ（ＢＯ６０１）に記載されてい
る自乗平均平方根粗さ（ＲＭＳ）を用いた。即ち、タイ
ヤのトレッドより発泡ゴムを切り出し、触針式表面粗さ
計（小坂研究所製）を用い、所定の試料寸法（長さ１０
ｍｍ、幅１０ｍｍ、厚さ５ｍｍ）、触針先端の半径Ｒ＝
２μｍ、測定力＝０．７ｍＮ、測定スキャニング長２．
５ｍｍの測定条件により試料表面を試料の長さ方向に
０．５ｍｍ間隔で１０個所、計１０個測定して平均し
た。発泡ゴムの氷上摩擦係数、特に０゜Ｃ付近の湿潤状
態における氷上の摩擦係数は、表面温度が−０．５°Ｃ
の氷上に前記表面粗さを測定した試料表面（試料寸法、
長さ１０ｍｍ、幅１０ｍｍ、厚さ５ｍｍ）と氷とを接触
させ、協和界面化学（株）製の動・静摩擦係数計を用い
て測定した。測定条件として荷重２ｋｇ／ｃｍ２、滑り
速度１０ｍｍ／ｓｅｃ、雰囲気温度−２°Ｃ、表面状態
は鏡面に近似、により行った。(3) Surface Roughness of Foamed Rubber and Friction Coefficient on Ice As the surface roughness that specifies the minute irregularities on the rubber surface of the foamed rubber, the root mean square roughness described in JIS Surface Roughness (BO601) is used. (RMS) was used. That is, the foamed rubber was cut out from the tread of the tire, and a predetermined sample size (length 10
mm, width 10 mm, thickness 5 mm), radius of the stylus tip R =
2 μm, measuring force = 0.7 mN, measuring scanning length 2.
Under the measurement condition of 5 mm, the surface of the sample was measured at 10 points at intervals of 0.5 mm in the length direction of the sample, and a total of 10 points were measured and averaged. The coefficient of friction of foamed rubber on ice, especially the coefficient of friction on ice in the wet state near 0 ° C, is such that the surface temperature is -0.5 ° C.
The surface of the sample whose surface roughness was measured on the ice (sample dimensions,
(Length 10 mm, width 10 mm, thickness 5 mm) was brought into contact with ice, and measurement was performed using a dynamic / static friction coefficient meter manufactured by Kyowa Interface Science Co., Ltd. As the measurement conditions, a load of 2 kg / cm 2 , a sliding speed of 10 mm / sec, an ambient temperature of −2 ° C., and a surface state of a mirror surface were used.
【００２０】（４）トレッド表面発熱温度 試験タイヤに正規内圧を充填した後、ドラム外径１．７
ｍの通常の室内ドラム試験機に速度１００ｋｍ／Ｈ、正
規荷重で押しつけて３時間走行し、トレッドの中央部の
表面温度を測定した。(4) Tread surface heat generation temperature After the test tire was filled with the normal internal pressure, the drum outer diameter was 1.7.
It was pressed against a normal indoor drum tester of m at a speed of 100 km / H with a regular load and run for 3 hours to measure the surface temperature of the central part of the tread.
【００２１】（５）耐摩耗性能 各試験タイヤ２本を排気量１５００ｃｃの乗用車のドラ
イブ軸に取り付け、テストコースのコンクリート路面上
を所定の速度で走行させた。溝深さの変化量を測定し、
比較タイヤを１００として指数表示した。数値は大きい
程耐摩耗性能が良好であることを示す。(5) Abrasion resistance performance Two test tires were attached to the drive shaft of a passenger car having a displacement of 1500 cc and run on a concrete road surface of a test course at a predetermined speed. Measure the amount of change in groove depth,
The comparative tire was set to 100 and indexed. The larger the numerical value, the better the wear resistance performance.
【００２２】（６）氷上制動性能 各試験タイヤ４本を排気量１５００ｃｃの乗用車に装着
し、外気温−５°Ｃの氷上で制動距離を測定した。比較
例タイヤを１００として指数表示した。数値は小さい程
制動が良好であることを示す。(6) Braking performance on ice Four test tires were mounted on a passenger car with a displacement of 1500 cc, and the braking distance was measured on ice with an outside air temperature of -5 ° C. The comparative tire was set to 100 and indexed. The smaller the numerical value, the better the braking.
【００２３】（７）一般路面上の操縦安定性能 操縦安定性能は、試験車に試験タイヤを装着し、夏季の
一般舗装路面を所定の速度で走行し、走行中の操舵性、
安定性を１０段階評価法で試験し、平均し、表４中の比
較例３をコントロール（基準）として＋、−で示した。
＋は良好、−は不良を示す。(7) Steering stability performance on a general road surface The steering stability performance is obtained by mounting a test tire on a test vehicle and traveling at a predetermined speed on a general pavement surface in summer,
Stability was tested by a 10-point evaluation method, averaged, and Comparative Example 3 in Table 4 was shown as + and − as a control (reference).
+ Means good, and-means bad.
【００２４】以下、本発明の実施例を図面に基づいて説
明する。 （第１〜５実施例、比較例１、２） 図１、２は本発明に係る空気入りタイヤの第１実施例を
示す図である。先ず、構成について説明する。図１にお
いて、空気入りタイヤ（タイヤサイズ１６５ＳＲ１３）
１はタイヤのケース２と、発泡ゴムからなりケース２の
クラウン部２ａを被覆するトレッド３とを有している。
ケース２は、一対のビード部５と、ビード部５間にほぼ
放射方向に配置したゴム引きコードからなるカーカス部
６と、カーカス部６のクラウン部にほぼタイヤ円周方向
に配置したベルト部７およびカーカス部のタイヤ軸方向
両側部を被覆するサイドウォールゴム８とから構成され
ている。Embodiments of the present invention will be described below with reference to the drawings. (First to fifth examples, comparative examples 1 and 2) FIGS. 1 and 2 are views showing a first example of the pneumatic tire according to the present invention. First, the configuration will be described. In FIG. 1, a pneumatic tire (tire size 165SR13)
Reference numeral 1 denotes a tire case 2 and a tread 3 made of foamed rubber and covering the crown portion 2a of the case 2.
The case 2 includes a pair of bead portions 5, a carcass portion 6 made of a rubberized cord disposed substantially radially between the bead portions 5, and a belt portion 7 disposed on a crown portion of the carcass portion 6 in a tire circumferential direction. And a side wall rubber 8 that covers both sides of the carcass portion in the tire axial direction.
【００２５】トレッド３は、トレッド３の表部３ａ側で
両ショルダ部間に発泡ゴム層１０を有し、発泡ゴム層１
０はトレッド３の全体積Ｖの少なくとも１０％以上の体
積を有し、この実施例ではトレッドの全体積Ｖと同じ１
００％の体積である。発泡ゴム層１０は発泡ゴム１１か
らなり、発泡ゴム１１は、表１に示すようにトレッドの
ゴム組成物（組成物３）、即ち、ガラス転移温度−６０
゜Ｃ以下の重合物（天然ゴム（ガラス転移温度−７２°
Ｃ）およびポリブタジエンゴム（ガラス転移温度−１０
０゜Ｃ）からなるゴム成分を含有し、且つ、これに通常
の配合剤および発泡剤（ジニトロソ・ペンタメチレンポ
テトラミンおよび尿素）を加えたものであり、通常のタ
イヤ製造方法にしたがって成型し、加熱・加圧する際、
発泡し独立気泡（図には黒点にて示している。）１３を
形成する。The tread 3 has a foamed rubber layer 10 between both shoulder portions on the front portion 3a side of the tread 3, and the foamed rubber layer 1
0 has a volume of at least 10% or more of the total volume V of the tread 3, and in this embodiment is equal to the total volume V of the tread 1
The volume is 00%. The foamed rubber layer 10 is composed of a foamed rubber 11, and the foamed rubber 11 is, as shown in Table 1, a rubber composition of tread (composition 3), that is, a glass transition temperature of −60.
Polymers below ° C (natural rubber (glass transition temperature -72 °
C) and polybutadiene rubber (glass transition temperature-10)
It contains a rubber component consisting of 0 ° C.) and is added with a usual compounding agent and a foaming agent (dinitroso pentamethylene potetramine and urea), and is molded according to a usual tire manufacturing method, When heating / pressurizing
It foams to form closed cells (indicated by black dots in the figure) 13.
【００２６】[0026]
【表１】 [Table 1]
【００２７】第１実施例に用いた発泡ゴム１１は、表２
（組成物３）に示すように、発泡率Ｖｓ１２％で、平均
気泡径２４μｍの独立気泡を有し、気泡直径３０〜２０
０μｍの独立気泡を単位面積１ｍｍ２当たり５０個を有
している。また、発泡ゴム１１の氷上摩耗係数は０．０
３７（表面粗さ２．３ＲＭＳ（μｍ））であり、通常の
もの（０．０１〜０．０２）より大きい。トレッド３以
外の構成および製造方法は通常の空気入りラジアルタイ
ヤと同じであり、詳細な説明は省略する。タイヤの性能
は、トレッド発熱温度が５９°Ｃで耐摩耗性能が９０、
氷上制動性能が９５であり、良好な氷上制動性能を示し
ている。The foamed rubber 11 used in the first embodiment is shown in Table 2.
As shown in (Composition 3), the foaming rate was Vs 12%, the closed cells had an average cell diameter of 24 μm, and the cell diameter was 30 to 20.
There are 50 closed cells of 0 μm per unit area of 1 mm 2 . The wear coefficient of ice of the foamed rubber 11 is 0.0.
37 (surface roughness 2.3 RMS (μm)), which is larger than usual (0.01 to 0.02). The configuration and manufacturing method other than the tread 3 are the same as those of a normal pneumatic radial tire, and detailed description thereof will be omitted. The tire has a tread heat generation temperature of 59 ° C and an abrasion resistance of 90,
The braking performance on ice is 95, which shows good braking performance on ice.
【００２８】[0028]
【表２】 [Table 2]
【００２９】次に、試験タイヤ（タイヤサイズ１６５Ｓ
Ｒ０３）を７種類（実施例５種、比較例２種）を準備
し、本発明の効果を確認した。詳細は表２に示す。第１
実施例は前述の図１に示すものである。第２〜５実施例
および比較例１、２は、トレッド３に、図１に示すよう
に、トレッド３の全体積の１００％の体積を有する発泡
ゴム層１０を用いた場合であり、第２〜第５実施例およ
び比較例１、２の発泡ゴム層の発泡ゴムには、それぞれ
表１の組成物４〜７および組成物１、２を用い、発泡剤
の配合量を変えて、発泡ゴムの物性を変えて製造した。
比較例１、２は気泡径３０〜２００μｍの独立気泡数が
単位面積１ｍｍ２当たり２０個未満で表面粗さが十分で
ない場合である。これらの試験タイヤは、前述以外は第
１実施例と同じである。Next, a test tire (tire size 165S
R03) was prepared in 7 kinds (5 kinds of examples and 2 kinds of comparative examples), and the effect of the present invention was confirmed. Details are shown in Table 2. First
The embodiment is shown in FIG. 1 described above. The second to fifth examples and the comparative examples 1 and 2 are cases in which the foamed rubber layer 10 having a volume of 100% of the total volume of the tread 3 is used for the tread 3, as shown in FIG. -Compositions 4 to 7 and Compositions 1 and 2 of Table 1 were used as the foamed rubber of the foamed rubber layers of the fifth example and Comparative Examples 1 and 2, respectively, and the compounding amount of the foaming agent was changed to obtain the foamed rubber. It was manufactured by changing the physical properties of.
Comparative Examples 1 and 2 are cases where the number of closed cells having a cell diameter of 30 to 200 μm is less than 20 per unit area 1 mm 2 and the surface roughness is not sufficient. These test tires are the same as the first embodiment except for the above.
【００３０】これらの試験タイヤの発泡ゴムの性質は、
平均気泡径、発泡率Ｖｓ、気泡径３０〜２００μｍの独
立気泡数および氷上摩擦係数（図２）について、上述し
た試験法により測定した。タイヤの氷上摩擦係数は、特
に、温度０゜Ｃ付近の湿潤状態において重要であるが、
図２に示すように（図中の番号は組成物の番号を示
す。）、第１〜５実施例に用いた発泡ゴムの組成物３〜
７の氷上摩擦係数は、比較例１、２に用いた組成物１、
２のものに比較して大幅に向上している。The properties of the foamed rubber of these test tires are:
The average cell diameter, the foaming rate Vs, the number of closed cells having a cell diameter of 30 to 200 μm, and the friction coefficient on ice (FIG. 2) were measured by the above-described test method. The coefficient of friction of a tire on ice is important especially in a wet condition near a temperature of 0 ° C.
As shown in FIG. 2 (the numbers in the figure indicate the numbers of the compositions), the foamed rubber compositions 3 to 3 used in Examples 1 to 5 were used.
The friction coefficient on ice of No. 7 is the composition 1 used in Comparative Examples 1 and 2.
It is significantly improved compared to the No. 2 one.
【００３１】試験タイヤの性能はトレッド表面の発熱温
度、耐摩耗性能、氷上制動性能について上述した試験法
により試験した。試験結果は表２に示す。これらの結果
から明らかなように、本発明を適用した第１〜第５実施
例は、比較例１、２に比較して、トレッド表面の発熱温
度の上昇もわずかで、発熱耐久性も充分であり、且つ、
耐摩耗性能も充分実用に耐るように確保されている。更
に、氷上制動性能も大幅に向上している。また、氷雪路
面上での駆動性能および操縦性能も充分であった。The performance of the test tire was tested by the above-described test methods for the heat generation temperature of the tread surface, wear resistance performance, and braking performance on ice. The test results are shown in Table 2. As is clear from these results, in the first to fifth examples to which the present invention is applied, the heat generation temperature of the tread surface is slightly increased and the heat generation durability is sufficient as compared with Comparative Examples 1 and 2. Yes, and
Abrasion resistance is also ensured so that it can be practically used. In addition, braking performance on ice has been greatly improved. In addition, the driving performance and maneuvering performance on ice and snow road surfaces were also sufficient.
【００３２】（第６〜８実施例、比較例３〜８） 次に、第６〜８実施例について説明する。第６〜８実施
例においては、発泡ゴムが本発明の前記発泡ゴムの特徴
（即ち、トレッドゴムの組成物）を有するとともに、ゴ
ム成分１００重量部に対し低温軟化剤２〜２０重量部を
含有する場合で、湿潤氷面において、タイヤの制動性、
駆動性、コーナリング性が改良されることを示す。先
ず、トレッドに加硫により独立気泡を形成する発泡剤と
ともに低温軟化剤を併用すると、トレッドの動的弾性率
および内部損失が調節でき、このため湿潤氷面の性能が
向上することを説明する。図３、図４は、それぞれ、ト
レッドゴムの動的弾性率および内部損夫の温度依存性を
示す。図４の実線は発泡剤および低温軟化剤を配合しな
い通常のトレッドゴムであり、少量の低温軟化剤を配合
したトレッドゴムはほぼこの実線と同じである。一点鎖
線は発泡剤を配合し独立気泡を有する発泡ゴムからなる
トレッドゴム（低温軟化剤を含まない）である。このこ
とから、発泡ゴムからなるトレッドゴムの動的弾性率は
下側にシフトする。(Sixth to Eighth Examples, Comparative Examples 3 to 8) Next, sixth to eighth examples will be described. In the sixth to eighth examples, the foamed rubber has the characteristics of the foamed rubber of the present invention (that is, the composition of the tread rubber), and contains 2 to 20 parts by weight of the low temperature softening agent to 100 parts by weight of the rubber component. In the case of doing, on the wet ice surface, the braking performance of the tire,
It shows that drivability and cornering are improved. First, it will be explained that when a low temperature softening agent is used together with a foaming agent that forms closed cells by vulcanization in the tread, the dynamic elastic modulus and internal loss of the tread can be adjusted, and thus the performance of the wet ice surface is improved. 3 and 4 show the temperature dependence of the dynamic elastic modulus and internal loss of the tread rubber, respectively. The solid line in FIG. 4 is a normal tread rubber containing no foaming agent and low-temperature softening agent, and the tread rubber containing a small amount of low-temperature softening agent is almost the same as this solid line. The one-dot chain line is a tread rubber (without a low-temperature softening agent) made of foamed rubber having a closed cell mixed with a foaming agent. From this, the dynamic elastic modulus of the tread rubber made of foamed rubber shifts to the lower side.
【００３３】図４の実線は通常のトレッドゴムであり、
発泡ゴムからなるトレッドゴムはほぼこの実線と同じで
ある。点線は低温軟化剤を配合したトレッドゴム（発泡
剤なし）である。このことから、低温軟化剤を配合した
トレッドゴムは左側（低温側）にシフトする。したがっ
て、矢印Ａを付した温度においては、発泡ゴムからなる
トレッドゴムは低温軟化剤配合のトレッドゴムに比較し
て動的弾性率を小さくでき、且つ、内部損失を大きくで
きる。このため、トレッドの湿潤氷面の性能（氷上摩擦
性能）は向上し有利になる。一方、低温軟化剤を配合し
たトレッドゴムは、発泡ゴムからなるトレッドゴムに比
較して動的弾性率が大きくでき、且つ、内部損失が小さ
くできるので、耐摩耗性能に有利になる。以上説明した
ことから、低温軟化剤と発泡剤を併用することにより耐
摩耗性を維持したまま湿潤氷面の性能を向上できる。The solid line in FIG. 4 is a normal tread rubber,
The tread rubber made of foamed rubber is almost the same as this solid line. The dotted line is the tread rubber (without foaming agent) blended with the low temperature softening agent. From this, the tread rubber containing the low temperature softening agent shifts to the left side (low temperature side). Therefore, at the temperature indicated by arrow A, the tread rubber made of foamed rubber can have a smaller dynamic elastic modulus and a larger internal loss than the tread rubber containing the low temperature softening agent. Therefore, the performance of the wet ice surface of the tread (friction performance on ice) is improved, which is advantageous. On the other hand, the tread rubber containing the low-temperature softening agent has a larger dynamic elastic modulus and a smaller internal loss as compared with the tread rubber made of foamed rubber, which is advantageous in wear resistance performance. From the above description, by using the low temperature softening agent and the foaming agent together, the performance of the wet ice surface can be improved while maintaining the wear resistance.
【００３４】次に、上述した点を発泡ゴムに用いた第６
〜８実施例につき説明する。第６〜８実施例および比較
例３〜８において、トレッドのゴム組成物は、それぞれ
表３に示す組成物８〜１６を用いた。組成物８、９は発
泡剤を配合せず、組成物１０〜１６は発泡剤の配合量を
順次変化させた場合である。また、組成物８、９、１
１、１３、１５は低温軟化剤の含有量を変化させた場合
であり、組成物１０、１２、１４、１６は比較のため
に、低温軟化剤を含有していない場合である。トレッド
以外の構成は第１実施例（図１）と同じである。Next, the sixth point using the above-mentioned points in the foamed rubber
8 Examples will be described. In Examples 6 to 8 and Comparative Examples 3 to 8, the rubber compositions of the treads were Compositions 8 to 16 shown in Table 3, respectively. Compositions 8 and 9 do not contain a foaming agent, and compositions 10 to 16 are cases where the compounding amount of the foaming agent is changed sequentially. Also, the compositions 8, 9, 1
1, 13, 15 are cases where the content of the low temperature softening agent was changed, and compositions 10, 12, 14, 16 were cases where the low temperature softening agent was not included for comparison. The configuration other than the tread is the same as that of the first embodiment (FIG. 1).
【００３５】[0035]
【表３】 [Table 3]
【００３６】トレッドゴムの性質は、その発泡率Ｖｓ、
温度０°Ｃにおける硬度、硬度の変化および耐摩擦性に
ついて試験し、また、このトレッドゴムを用いた空気入
りタイヤの性能は温度０°Ｃ付近および−２０°Ｃ付近
の氷上制動性能について上述した試験法によって試験
し、試験結果を表４に示す。The property of the tread rubber is that its foaming ratio Vs,
The hardness at 0 ° C, the change in hardness, and the abrasion resistance were tested, and the performance of the pneumatic tire using this tread rubber was as described above for the braking performance on ice near 0 ° C and -20 ° C. It tested by the test method and the test results are shown in Table 4.
【００３７】[0037]
【表４】 [Table 4]
【００３８】試験結果は表４に示すように、低温軟化剤
を含有する第６〜８実施例は、比較例３〜８に対して硬
度の低下も少なく、また、長期使用時の硬度変化も僅か
であり、耐摩耗性能を実用上十分に維持したまま、氷上
制動性能が大幅に向上している。As shown in Table 4, the test results show that the sixth to eighth examples containing the low temperature softening agent showed less decrease in hardness than the comparative examples 3 to 8 and the hardness change during long-term use. This is a small amount, and the braking performance on ice is greatly improved while maintaining sufficient wear resistance for practical use.
【００３９】[0039]
【発明の効果】本発明は、以上説明したように構成され
ているので、以下に記載されるような効果を奏する。耐
摩耗性能および発熱耐久性を損なうことなく、氷雪路面
上における制動性能、駆動性および操縦性等の氷雪性能
を大幅に向上することができるとともに、発泡ゴムに低
温軟化剤を含有させることにより氷上制動性能を更に大
幅に向上することができる。Since the present invention is configured as described above, it has the following effects. It is possible to significantly improve ice and snow performance such as braking performance, drivability and maneuverability on ice and snow road surfaces without deteriorating wear resistance performance and heat generation durability. It is possible to further improve the braking performance.
【図１】図１は本発明に係る空気入りタイヤの第１実施
例を示す一部断面図である。FIG. 1 is a partial sectional view showing a first embodiment of a pneumatic tire according to the present invention.
【図２】図２は表面粗さと氷上摩擦係数との関係を示す
グラフである。FIG. 2 is a graph showing the relationship between surface roughness and friction coefficient on ice.
【図３】図３は温度と動的弾性率との関係を示すグラフ
である。FIG. 3 is a graph showing the relationship between temperature and dynamic elastic modulus.
【図４】図４は温度と内部損失との関係を示すグラフで
ある。FIG. 4 is a graph showing the relationship between temperature and internal loss.
１、２１・・・空気入りタイヤ ２・・・・・・ケース ２ａ・・・・・ケースのクラウン部 ３・・・・・・トレッド ３ａ・・・・・トレッドの表部 ５・・・・・・ビード部 ６・・・・・・カーカス部 ７・・・・・・ベルト部 ８・・・・・・サイドウォールゴム ９・・・・・・ショルダ部 １０・・・・・発泡ゴム層 １１・・・・・発泡ゴム １３・・・・・独立気泡 1, 21 ... Pneumatic tire 2 ... Case 2a ... Crown part of case 3 ... Tread 3a ... Front part of tread 5 ... ..Bead 6 ... Carcass 7 ... Belt 8 ... Sidewall rubber 9 ... Shoulder 10 ... Foamed rubber layer 11: foam rubber 13: closed cells
Claims (1)
被覆するトレッドとを備えた空気入りタイヤにおいて、
トレッドの少なくとも表部側に発泡ゴム層が配置されて
おり、該発泡ゴム層がガラス転移温度−６０°Ｃ以下の
重合物を含有するゴム成分１００重量部に対して低温軟
化剤を２〜２０重量部含有する発泡ゴムからなり、該発
泡ゴムが発泡率Ｖｓ５〜５０％の範囲で平均気泡径５〜
１５０μｍの独立気泡を有することを特徴とする空気入
りタイヤ。1. A pneumatic tire having a tire case and a tread covering a crown portion of the case.
A foamed rubber layer is arranged at least on the front side of the tread, and the foamed rubber layer contains 2 to 20 parts of a low-temperature softening agent with respect to 100 parts by weight of a rubber component containing a polymer having a glass transition temperature of -60 ° C or less. The foamed rubber contains 5 parts by weight, and the foamed rubber has an average cell diameter of 5 to 5 in a range of a foaming rate Vs of 5 to 50%.
A pneumatic tire having 150 μm closed cells.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP5264276A JP2564760B2 (en) | 1993-09-27 | 1993-09-27 | Pneumatic tire |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP5264276A JP2564760B2 (en) | 1993-09-27 | 1993-09-27 | Pneumatic tire |
Related Parent Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP61235921A Division JP2568520B2 (en) | 1986-02-05 | 1986-10-02 | Pneumatic tire |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH07242104A JPH07242104A (en) | 1995-09-19 |
| JP2564760B2 true JP2564760B2 (en) | 1996-12-18 |
Family
ID=17400925
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP5264276A Expired - Lifetime JP2564760B2 (en) | 1993-09-27 | 1993-09-27 | Pneumatic tire |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP2564760B2 (en) |
Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP4908664B2 (en) * | 1999-07-30 | 2012-04-04 | 株式会社ブリヂストン | Pneumatic tires for motorcycles |
| EP2193938A4 (en) * | 2007-08-10 | 2010-09-29 | Bridgestone Corp | Pneumatic tire |
| JP6993191B2 (en) * | 2017-11-16 | 2022-01-13 | Ｔｏｙｏ Ｔｉｒｅ株式会社 | Rubber composition for tires and pneumatic tires using them |
-
1993
- 1993-09-27 JP JP5264276A patent/JP2564760B2/en not_active Expired - Lifetime
Also Published As
| Publication number | Publication date |
|---|---|
| JPH07242104A (en) | 1995-09-19 |
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