JP4201943B2 - Rubber composition and pneumatic tire - Google Patents

Description

（式中、Ｒは炭素数６〜１８の芳香族基、または炭素数７〜２４のアルキル芳香族基を表し、ｘおよびｙは０〜３のいずれかの整数をそれぞれ独立に表す。）
【００１０】
【化５】

（式中、Ｒ ¹ は炭素数８〜２４の飽和または不飽和のアルキル基、または炭素数７〜２４のアラルキル基を表し、Ｒ ² およびＲ ³ は、水素原子、炭素数１〜１２の飽和もしくは不飽和のアルキル基、炭素数７〜１２のアラルキル基、−（ＣＨ₂Ｏ）_pＨ、−（ＣＨ₂ＣＨ₂Ｏ）_pＨ、−（ＣＨ（ＣＨ₃）ＣＨ₂Ｏ）_pＨ、または−（ＣＨ₂ＣＨ₂ＣＨ₂Ｏ）_pＨをそれぞれ独立に表し、Ｒ²およびＲ³中のｐの合計値は１〜４のいずれかの整数である。）
【００１１】
【化６】

（式中、Ｒ¹ 〜Ｒ³ は前記と同様であり、Ｒ⁴ は炭素数６〜２４の飽和もしくは不飽和のアルキル基、炭素数６〜２４のアリール基、または炭素数７〜２４のアラルキル基を表す。）
【００１２】
チアゾール系加硫促進剤およびチウラム系加硫促進剤のうち少なくとも１種をさらに含むゴム組成物において本発明は一層効果的である。
前記アミンおよびアミン付加塩の一般式中のＲ² およびＲ³ が、炭素数１〜８の飽和または不飽和のアルキル基をそれぞれ独立に表し、アミンおよびアミン付加塩のそれぞれについて、Ｒ¹ 、Ｒ² およびＲ³ が有する炭素数の合計値が１０〜２４であると好ましい。
【００１３】
前記ビスマレイミドが、ゴム成分１００重量部に対して０．１〜３０重量部の割合で配合されるとより好ましく、さらに、前記アミン化合物がビスマレイミドの５０〜４００重量％の割合で配合されるとより一層好ましい。また、ビスマレイミドが、Ｎ，Ｎ’−（４，４’−ジフェニルメタン）ビスマレイミドであり、また、アミン付加塩が、ジメチルステアリルアミン・ステアリン酸塩、またはメチルステアリルアミン・ステアリン酸塩であるとさらに好ましい。また、ゴム成分中、５０重量％以上がスチレン・ブタジエン共重合体ゴムである場合により効果的である。
【００１４】
（２）本発明の空気入りタイヤは、上記のゴム組成物をゴム部材として適用したことを特徴とする。
前記ゴム部材がトレッドであると好ましい。
【００１５】
【発明の実施の形態】
以下に本発明を詳細に説明する。
本発明で好適に使用できるビスマレイミドとしては、Ｎ，Ｎ′−１，２−フェニレンジマレイミド、Ｎ，Ｎ′−１，３−フェニレンジマレイミド、Ｎ，Ｎ′−１，４−フェニレンジマレイミド、Ｎ，Ｎ’−（４，４’−ジフェニルメタン）ビスマレイミド、２，２−ビス［４−（４−マレイミドフェノキシ）フェニル］プロパン、ビス（３−エチル−５−メチル−４−マレイミドフェニル）メタン等を例示できる。
なお、ビスマレイミドの前記一般式中、ｘまたはｙが４以上では、分子量が大きくなり、配合量の割に、目的とする動的貯蔵弾性率の増加効果が得られないため不都合である。
【００１６】
また、アミン化合物としては以下のとおりである。
前記アミンおよびアミン付加塩の前記一般式中、Ｒ¹ がとりうる前記特定のアルキル基は、直鎖状、分岐状、環状のいずれでもよく、各種オクチル基、各種ノニル基、各種デシル基、各種ドデシル基、各種テトラデシル基、各種ヘキサデシル基、各種オクタデシル基、各種ベへニル基、各種オクテニル基、各種デセニル基、オレイル基、シクロオチクル基、シクロドデシル基、各種シクロオクテニル基、各種シクロドデセニル基などが挙げられる。
また、前記アミンおよびアミン付加塩の前記一般式中、Ｒ¹ がとりうる前記特定のアリール基は、芳香環上に、直鎖状、分岐状、環状の低級アルキル基などの適当な置換基を有していてもよく、その例としては、フェニル基、各種トリル基、各種キシリル基、α−またはβ−ナフチル基、各種メチルナフチル基、各種ジメチルナフチル基などが挙げられる。
また、前記アミンおよびアミン付加塩の前記一般式中、Ｒ¹ がとりうる前記特定のアラルキル基は、芳香環上に、直鎖状、分岐状、環状の低級アルキル基などの適当な置換基を有していてもよく、その例としては、ベンジル基、各種メチルベンジル基、フェネチル基、各種メチルフェネチル基、各種ナフチルメチル基、各種（メチルナフチル）メチル基などが挙げられる。
【００１７】
また、前記アミンおよびアミン付加塩の前記一般式中、Ｒ² およびＲ³ がとりうる前記特定のアルキル基は、直鎖状、分岐状、環状のいずれでもよく、その例としては、メチル基、エチル基、ｎ−プロピル基、イソプロピル基、各種ブチル基、各種ペンチル基、各種ヘキシル基、各種オクチル基、各種デシル基、各種ドデシル基、プロペニル基、アリル基、各種ペンテニル基、各種ヘキセニル基、各種オクテニル基、各種デセニル基、シクロペンチル基、シクロヘキシル基、シクロオチクル基、各種シクロペンテニル基、各種シクロヘキセニル基、各種シクロオクテニル基などが挙げられる。
また、前記アミンおよびアミン付加塩の前記一般式中、Ｒ² およびＲ³ がとりうる前記特定のアリール基は、芳香環上に、直鎖状、分岐状、環状の低級アルキル基などの適当な置換基を有していてもよく、その例としては、フェニル基、各種トリル基、各種キシリル基、α−若しくはβ−ナフチル基、各種メチルナフチル基などが挙げられる。
また、前記アミンおよびアミン付加塩の前記一般式中、Ｒ² およびＲ³ がとりうる前記特定のアラルキル基は、芳香環上に、直鎖状、分岐状、環状の低級アルキル基などの適当な置換基を有していてもよく、その例としてはベンジル基、各種メチルベンジル基、フェネチル基、各種メチルフェネチル基、各種ナフチルメチル基などが挙げられる。
【００１８】
一方、前記アミン付加塩の前記一般式中、Ｒ⁴ がとり得る前記特定のアルキル基は、直鎖状、分岐状、環状のいずれでもよく、その例としては、各種ヘキシル基、各種オクチル基、各種ノニル基、各種デシル基、各種ドデシル基、各種テトラデシル基、各種ヘキサデシル基、各種オクタデシル基、各種ベヘニル基、各種ヘキセニル基、各種オクテニル基、各種デセニル基、オレイル基、シクロヘキシル基、シクロオクチル基、シクロドデシル基、各種シクロヘキセニル基、各種シクロオクテニル基、各種シクロドデセニル基などが挙げられる。
また、前記アミン付加塩の前記一般式中、Ｒ⁴ がとり得る前記特定のアリール基およびアラルキル基は、芳香環上に、直鎖状、分岐状、環状の低級アルキル基などの適当な置換基をそれぞれ有していてもよく、それらの例としては、前記Ｒ¹ の説明において、アリール基及びアラルキル基として例示したものと同じものを挙げることができる。
【００１９】
本発明のアミンおよびアミン付加塩を構成するアミン類の好ましい例としては、デシルアミン、ラウリルアミン、ミリスチルアミン、パルミチルアミン、ステアリルアミン、ベヘニルアミン、オレイルアミン、モノメチルデシルアミン、モノメチルラウリルアミン、モノメチルミリスチルアミン、モノメチルパルミチルアミン、モノメチルステアリルアミン、モノメチルオレイルアミン、モノエチルデシルアミン、モノエチルラウリルアミン、モノエチルミリスチルアミン、モノエチルパルミチルアミン、モノエチルステアリルアミン、モノエチルオレイルアミン、モノプロピルデシルアミン、モノプロピルラウリルアミン、モノプロピルミリスチルアミン、モノプロピルパルミチルアミン、モノプロピルステアリルアミン、モノプロピルオレイルアミン、ジメチルデシルアミン、ジメチルラウリルアミン、ジメチルミリスチルアミン、ジメチルパルミチルアミン、ジメチルステアリルアミン、ジメチルオレイルアミン、ジエチルデシルアミン、ジエチルラウリルアミン、ジエチルミリスチルアミン、ジエチルパルミチルアミン、ジエチルステアリルアミン、ジエチルオレイルアミン、メチルエチルデシルアミン、メチルエチルラウリルアミン、メチルエチルミリスチルアミン、メチルエチルパルミチルアミン、メチルエチルステアリルアミン、メチルエチルオレイルアミン、ジ（ヒドロキシエチル）デシルアミン、ジ（ヒドロキシエチル）ラウリルアミン、ジ（ヒドロキシエチル）ミリスチルアミン、ジ（ヒドロキシエチル）パルミチルアミン、ジ（ヒドロキシエチル）ステアリルアミン、ジ（ヒドロキシエチル）オレイルアミンなどが挙げられる。これらの中で、特にＲ² 及びＲ³ がそれぞれ炭素数１〜８の飽和または不飽和のアルキル基であって、Ｒ¹ 、Ｒ² およびＲ³ が有する炭素数の合計値がそれぞれ１０〜２４の第三級アルキルアミンが特に好適である。
【００２０】
一方、本発明のアミン付加塩を構成するカルボン酸としては、Ｒ⁴ の炭素数が１０〜２０の飽和または不飽和の直鎖脂肪酸が好ましい。このカルボン酸の例としては、カプリン酸、ラウリン酸、ミリスチン酸、パルミチン酸、ステアリン酸、アラキン酸、ベヘン酸、オレイン酸などが挙げられる。
本発明のアミン付加塩としては、分子量が４００〜８００の範囲にあるものが好ましい。
なお、アミン付加塩にはフレークや粒の強度を向上させ、夏場の高温時に起こりやすい融着を防ぐ目的で、リン酸塩、亜リン酸塩等の無機塩をアミン付加塩の０．１〜１０重量％程度含ませてもよい。
また、本発明において、ビスマレイミドの配合量は、ゴム成分１００重量部に対して、０．１〜３０重量部であると好ましいが、これは、０．１重量部未満では配合の効果が充分得られないことがあり、３０重量部を超えると破壊物性が低下する傾向があるからである。同様の観点から、好ましくは０．５〜５．０重量部である。
さらに、アミン化合物の配合量は、ビスマレイミドの５０〜４００重量％であると好ましいが、これは、５０重量％未満ではビスマレイミドとの組み合わせによる相乗効果が得られず、４００重量％を超えると加硫が早くなり、ゴムが焦け易くなるからである。同様の観点から、好ましくは１００〜２００重量％である。
【００２１】
また、 本発明で使用できる加硫促進剤は、特に限定されるものではないが、好ましくはＭＢＴ（２−メルカプトベンゾチアゾール）、ＤＭ（ジベンゾチアジルジサルファイド) 、 ＣＢＳ（Ｎ−シクロヘキシル−２−ベンゾチアジルスルフェンアミド）、ＴＢＢＳ（Ｎ−ｔ−ブチル−２ーベンゾチアジルスルフェンアミド）、ＴＢＳＩ（Ｎ−ｔ−ブチル−２ーベンゾチアジルスルフェンイミド）等のベンゾチアゾール系の加硫促進剤、ＤＰＧ（ジフェニルグアニジン）等のグアニジン系の加硫促進剤、テトラオクチルチウラムジスルフィド、テトラベンジルチウラムジスルフィド等のチウラム系加硫促進剤、ジアルキルジチオリン酸亜鉛などの加硫促進剤等を例示でき、その使用量は、ゴム成分１００重量部に対して０．１〜５重量部が好ましく、より好ましくは０．２〜３重量部である。
【００２２】
本発明は、チアゾール系加硫促進剤および／またはチウラム系加硫促進剤を配合してなる硫黄加硫系ゴム組成物およびタイヤに対して極めて効果的である。
本発明では、天然ゴムおよび合成ジエン系ゴムを使用できるが、合成ジエン系ゴムでは、シス−１，４−ポリイソプレン、スチレンブタジエン共重合体、低シス−１，４−ポリブタジエン、高シス−１，４−ポリブタジエン、エチレン−プロピレン−ジエン共重合体、クロロプレン、ハロゲン化ブチルゴム、アクリロニリトル−ブタジエンゴム等を例示でき、天然ゴムおよび合成ジエン系ゴムは、単独使用のみならずブレンドして使用できる。
【００２３】
好ましいゴムは、天然ゴム、シス−１，４−ポリイソプレン、スチレンブタジエン共重合体、ポリブタジエンである。
なお、ゴム成分中、スチレン・ブタジエン共重合体ゴムが５０重量％以上含まれていると、本発明の目的であるビスマレイミドとアミン類との組み合わせによる改良効果が最も明確になる点で好ましい。
また、本発明では、補強性充填剤として、カーボンブラック、シリカ、炭酸カルシウム、酸化チタンなどの少なくとも１種を使用することができ、好ましくはカーボンブラックおよびシリカである。
【００２４】
補強性充填剤の配合量は、ゴム成分１００重量部に対して、２０〜１５０重量部が好ましい。これは、２０重量部未満では、加硫物の破壊特性および耐摩耗性などが十分でなく、１５０重量部を超えると、作業性等において好ましくないからである。同様の観点から、２５〜８０重量部がより好ましい。
補強性充填剤として用いるカーボンブラックを例示すると、ＨＡＦ、ＩＳＡＦ、ＳＡＦ等が挙げられ、カーボンブラックとシリカとを併用する場合の配合比は、配合目的に応じて任意に変化させることができる。
【００２５】
本発明におけるゴム組成物には、上記ゴム成分、補強性充填剤、ビスマレイミド、アミン化合物の他に、必要に応じて、ゴム工業で通常使用されているシランカップリング剤、加硫剤、加硫促進剤、加硫促進助剤、酸化防止剤、オゾン劣化防止剤、老化防止剤、プロセス油、亜鉛華（ＺｎＯ）、ステアリン酸、等を配合することができる。
【００２６】
本発明で使用できる加硫剤としては、例えば、硫黄等が挙げられ、これらの使用量は、ゴム成分１００重量部に対して、硫黄分として０．１〜１０重量部、好ましくは０．５〜５．０重量部である。０．１重量部未満では加硫ゴムの破壊特性、耐摩耗性が低下し、１０重量部を超えるとゴム弾性が失われる傾向があるからである。
【００２７】
本発明で使用できるプロセス油としては、例えば、パラフィン系、ナフテン系、アロマチック系等を挙げることかでき、破壊特性、耐摩耗性を重視する用途にはアロマチック系が、また、低発熱性、低温特性を重視する用途にはナフテン系またはパラフィン系がそれぞれ好ましく用いられる。その使用量は、ゴム成分１００重量部に対して１００重量部以下が好ましく、これは、１００重量部を越えると加硫ゴムの破壊特性、低発熱性が低下する傾向があるからである。
【００２８】
本発明のゴム組成物は、上記ゴム成分、ビスマレイミド、ヒドラジド、補強性充填剤等をロール、インターナルミキサー等の混練り機を用いて混練りすることにより得られ、成形加工後、加硫を行い、タイヤトレッド、アンダートレッド、カーカス、サイドウォール、ビード部等のゴム部材としてのタイヤ用途を始め、防振ゴム、ベルト、ホースその他工業品等の用途にも好適に使用できる。
【００２９】
【実施例】
以下に本発明をより具体的に説明する。
表１および、表２〜表４記載の各配合成分を、５００ｍｌのラボプラストミルおよび３インチロールを使用して、混練り配合し、未加硫のゴム組成物を得た。各ゴム組成物について、下記（１）（２）の方法によりキュラスト試験およびブローポイント試験を行い、また、これらの配合ゴムの加硫後の引張試験、動的粘弾性試験を下記（３）、 （４）の方法により測定した。これらの結果を表２〜表４に示す。
【００３０】
（１）キュラスト試験
米国フレキシス社製、ＭＤＲ２０００を用い１４５℃で測定した。
Ｍ_H 、Ｍ_L はそれぞれトルクの最大値、最小値であり、Ｔ₁₀、Ｔ₉₀ は加硫反応によるトルクの上昇が全体のそれぞれ１０％、９０％に達した時間を表す。各データは比較例１、６または８をそれぞれ１００として指数で表す。
【００３１】
（２）ブローポイント試験
東洋精機（株）製、ブローポイント測定機を使用して、１７０℃で、活性化エネルギー２０ｋｃａｌの条件で測定した。各データは比較例１、６または８をそれぞれ１００として指数で表す。この指数が大きい程ブローポイント値が大きく、より長い加硫時間が必要で生産性が悪化することを表す。
【００３２】
（３）引張試験
１４５℃で（１）で得たＴ₉₀の１．５倍にあたる加硫時間で加硫後、ＪＩＳＫ６３０１−１９７５に基づいて引張試験を行い（３号試験片使用）、３００％伸長時弾性率（Ｍ₃₀₀ ）を測定した。同様に、各データは比較例１、６または８をそれぞれ１００として指数で表す。
【００３３】
（４）動的粘弾性試験
東洋精機（株）製、スペクトロメーター（動的粘弾性測定試験機）を用い、周波数５２Ｈｚ、測定温度３０℃、歪１％でＥ’（動的貯蔵弾性率）、 tanδ（損失係数）を測定した。同様に、各データは比較例１、６または８をそれぞれ１００として指数で表す。
【００３４】
さらに、実施例２、４、１０、１１、１３、１４、１５、比較例１、３、６、７、８、９のゴム組成物をトレッドゴムとして用いて、１８５／７０Ｒ１４サイズのトレッド（一層構造）の空気人りタイヤを試作し、各タイヤの性能を実車走行にて操縦性について評価した。
（５）操縦性
水を撒いてウェット路としたテストコースにて、 各新品タイヤを装着したＦＦ４ドアセダンを用いて実車走行を行い、駆動性、制動性、ハンドル応答性、操縦時のコントロール性を、比較例１、６または８のタイヤをそれぞれコントロールタイヤとして、テストドライバーが総合評価した。
＋１：コントロールタイヤに比べてプロテストドライバーが微妙に分かる程度に良いと感じる場合
＋２：コントロールタイヤに比べてプロテストドライバーが明確に分かる程度に良いと感じる場合
＋３：コントロールタイヤに比べて一般ドライバーのうち熟練したドライバーが分かる程度に良いと感じる場合
＋４：コントロールタイヤに比べて一般ドライバーが分かる程度に良いと感じる場合
【００３５】
【表１】

【００３６】
ノクセラーＤ：ＤＰＧ
ビスマレイミド：Ｎ，Ｎ’−（４，４’−ジフェニルメタン）ビスマレイミド（三井化学ファイン（株）製ＢＭＩ−Ｓ）
化合物Ａ：ジメチルステアリルアミン・ステアリン酸塩
化合物Ｂ：ステアリルアミン・ステアリン酸塩
化合物Ｃ：ジメチルステアリルアミン
【００３７】
【表２】

【００３８】
【表３】

【００３９】
【表４】

【００４０】
上記の結果より、比較例１〜４はビスマレイミドの添加により、Ｍ₃₀₀ 値をほぼ維持したまま、Ｅ′値を大幅に増加でき、ウェット路面での操縦性が向上したが、加硫反応終了時間（Ｔ₉₀）は大幅に増加し、生産性は大幅に低下した。
比較例５は、アミン付加塩自身は加硫反応を早める傾向にあるが、比較例１に対して１０％以下であり、大きな効果ではない。
これに対して実施例１〜９はビスマレイミドとアミン化合物を併用することで、加硫の遅れが大幅に改善されると共に、ブローポイントが大幅に改良される。
さらに、実施例１０〜１５のシリカ配合量を多くした系においても、ビスマレイミドとアミン化合物を併用することで、同様の相乗効果を示した。
【００４１】
【発明の効果】
本発明によると、作業性を高めて、生産性良く、弾性率の高いトレッドゴム等に適したゴム組成物を提供できる。また、このようなゴムをトレッドに使用した空気入りタイヤは、操縦性に優れている。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a rubber composition and a pneumatic tire, and particularly to a technique for obtaining a rubber composition and a pneumatic tire having good workability and high elastic modulus.
[0002]
[Prior art]
In recent years, with higher horsepower and higher speed of automobiles, higher steering stability and higher grip performance than ever have been required for tire performance.
On the other hand, bismaleimide has been studied in the rubber industry as a cross-linking agent. However, in JP-A-63-99251, bismaleimide is blended with styrene-butadiene copolymer rubber (SBR) to achieve high heat resistance and high resistance. It has been reported that it can be compatible with mobility.
[0003]
[Problems to be solved by the invention]
Recently, the present inventor has not only improved the heat resistance but also increased the dynamic storage elastic modulus (E ′), particularly when the bismaleimide is blended with rubber containing 50% by weight or more of SBR. It has been found that when a rubber composition containing maleimide is used for a tread, the handling stability is improved.
[0004]
However, when a large amount of bismaleimide is blended with the SBR-containing rubber as described above, the vulcanization reaction is inhibited by the bismaleimide, and it takes a long time to vulcanize. In order to vulcanize without leaving any bubbles in rubber products, longer vulcanization is required and productivity is greatly reduced, which is practical. Not.
[0005]
To solve this problem, it is naturally considered to use accelerators that accelerate the vulcanization reaction, so-called super accelerators, such as guanidines, dithiocarbamates, and xanthates. The blow point cannot be improved so much that the rise time is shortened and the burn time (scorch time) of the unvulcanized rubber is shortened.
[0006]
Therefore, as a result of investigating the cause of inhibition of the vulcanization reaction by bismaleimide, the present inventor caused the reaction between the vulcanization accelerator and bismaleimide earlier than the vulcanization reaction, particularly in the SBR compounding system, As a result, it was found that vulcanization was inhibited. This is particularly noticeable when thiazole and thiuram vulcanization accelerators are used. Furthermore, due to the reaction between bismaleimide and the vulcanization accelerator, a part of bismaleimide is decomposed and gasified, so a larger amount of gas is generated in the rubber and the blow point may be deteriorated. found.
SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a technique that can eliminate the disadvantages described above, further improve the merit of high elasticity by bismaleimide, and avoid the disadvantage of productivity due to vulcanization delay.
[0007]
[Means for Solving the Problems]
As mentioned above, it was found that the deterioration in productivity due to the use of bismaleimide was due to the reaction between bismaleimide and a vulcanization accelerator, so this reaction was suppressed and the original purpose of dynamic storage elasticity As a result of examining compounds that achieve improvement in tire performance by increasing the rate, it was found that the object can be achieved by blending a specific bismaleimide and an amine compound, and the present invention has been completed.
[0008]
The present invention has the following configuration.
(1) The rubber composition of the present invention includes at least one bismaleimide represented by the following general formula [Chemical Formula 4] in a rubber component composed of at least one rubber among natural rubber and synthetic diene rubber. And at least one of amine compounds represented by the following general formulas [Chemical Formula 5] and [Chemical Formula 6].
[0009]
[Formula 4]

(In the formula, R represents an aromatic group having 6 to 18 carbon atoms or an alkyl aromatic group having 7 to 24 carbon atoms, and x and y each independently represents an integer of 0 to 3)
[0010]
[Chemical formula 5]

(Where R ¹ Saturated or unsaturated alkyl group having 8 to 24 carbon atoms or an aralkyl group having a carbon number having 7 to 24, R ² and R ³ are hydrogen atom, an alkyl group of saturated or unsaturated having 1 to 12 carbon atoms, , An aralkyl group having 7 to 12 carbon atoms, — (CH ₂ O) _p H, — (CH ₂ CH ₂ O) _p H, — (CH (CH ₃ ) CH ₂ O) _p H, or — (CH ₂ CH ₂ CH ₂ O) _p H is independently represented, and the total value of p in R ² and R ³ is an integer of 1 to 4. )
[0011]
[Chemical 6]

Wherein R ^{1 to} R ³ are the same as defined above, and R ⁴ is a saturated or unsaturated alkyl group having 6 to 24 carbon atoms, an aryl group having 6 to 24 carbon atoms, or an aralkyl having 7 to 24 carbon atoms. Represents a group.)
[0012]
The present invention is more effective in a rubber composition further including at least one of a thiazole vulcanization accelerator and a thiuram vulcanization accelerator.
R ² and R ^{3 in} the general formulas of the amine and amine addition salt each independently represent a saturated or unsaturated alkyl group having 1 to 8 carbon atoms, and for each of the amine and amine addition salt, R ¹ , R 3 The total number of carbon atoms of ² and R ³ is preferably 10 to 24.
[0013]
More preferably, the bismaleimide is blended in a proportion of 0.1 to 30 parts by weight with respect to 100 parts by weight of the rubber component, and the amine compound is blended in a proportion of 50 to 400% by weight of the bismaleimide. And even more preferable. The bismaleimide is N, N ′-(4,4′-diphenylmethane) bismaleimide, and the amine addition salt is dimethylstearylamine stearate or methylstearylamine stearate. Further preferred. Further, it is more effective when 50% by weight or more of the rubber component is styrene / butadiene copolymer rubber.
[0014]
(2) The pneumatic tire of the present invention is characterized in that the above rubber composition is applied as a rubber member.
The rubber member is preferably a tread.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
The present invention is described in detail below.
Examples of the bismaleimide that can be suitably used in the present invention include N, N′-1,2-phenylene dimaleimide, N, N′-1,3-phenylene dimaleimide, and N, N′-1,4-phenylene dimaleimide. N, N ′-(4,4′-diphenylmethane) bismaleimide, 2,2-bis [4- (4-maleimidophenoxy) phenyl] propane, bis (3-ethyl-5-methyl-4-maleimidophenyl) Examples include methane.
In the above general formula of bismaleimide, when x or y is 4 or more, the molecular weight becomes large, and it is inconvenient because the intended effect of increasing the dynamic storage modulus cannot be obtained for the blending amount.
[0016]
Moreover, it is as follows as an amine compound.
In the general formula of the amine and the amine addition salt, the specific alkyl group that R ¹ can take may be linear, branched, or cyclic. Various octyl groups, various nonyl groups, various decyl groups, various types Examples include dodecyl group, various tetradecyl groups, various hexadecyl groups, various octadecyl groups, various behenyl groups, various octenyl groups, various decenyl groups, oleyl group, cyclooctyl group, cyclododecyl group, various cyclooctenyl groups, various cyclododecenyl groups, etc. .
In the general formula of the amine and the amine addition salt, the specific aryl group which R ¹ can take has an appropriate substituent such as a linear, branched or cyclic lower alkyl group on the aromatic ring. Examples thereof may include a phenyl group, various tolyl groups, various xylyl groups, α- or β-naphthyl groups, various methylnaphthyl groups, various dimethylnaphthyl groups, and the like.
Further, in the formula of the amine and amine addition salts, the specific aralkyl group R ¹ can take is, on the aromatic ring, linear, branched, a suitable substituent such as a cyclic lower alkyl group Examples thereof may include a benzyl group, various methylbenzyl groups, phenethyl groups, various methylphenethyl groups, various naphthylmethyl groups, various (methylnaphthyl) methyl groups, and the like.
[0017]
In the general formula of the amine and the amine addition salt, the specific alkyl group that R ² and R ³ can take may be linear, branched, or cyclic. Examples thereof include a methyl group, Ethyl group, n-propyl group, isopropyl group, various butyl groups, various pentyl groups, various hexyl groups, various octyl groups, various decyl groups, various dodecyl groups, propenyl group, allyl group, various pentenyl groups, various hexenyl groups, various types Examples include octenyl group, various decenyl groups, cyclopentyl group, cyclohexyl group, cyclooctyl group, various cyclopentenyl groups, various cyclohexenyl groups, and various cyclooctenyl groups.
In addition, in the general formula of the amine and amine addition salt, the specific aryl group that R ² and R ³ can take is an appropriate one such as a linear, branched, or cyclic lower alkyl group on the aromatic ring. It may have a substituent, and examples thereof include phenyl group, various tolyl groups, various xylyl groups, α- or β-naphthyl group, various methylnaphthyl groups, and the like.
In addition, in the general formula of the amine and amine addition salt, the specific aralkyl group that R ² and R ³ can take is an appropriate one such as a linear, branched, or cyclic lower alkyl group on the aromatic ring. It may have a substituent, and examples thereof include benzyl group, various methylbenzyl groups, phenethyl group, various methylphenethyl groups, various naphthylmethyl groups, and the like.
[0018]
On the other hand, in the general formula of the amine addition salt, the specific alkyl group that R ⁴ can take may be linear, branched, or cyclic. Examples thereof include various hexyl groups, various octyl groups, Various nonyl groups, various decyl groups, various dodecyl groups, various tetradecyl groups, various hexadecyl groups, various octadecyl groups, various behenyl groups, various hexenyl groups, various octenyl groups, various decenyl groups, oleyl groups, cyclohexyl groups, cyclooctyl groups, Examples thereof include a cyclododecyl group, various cyclohexenyl groups, various cyclooctenyl groups, and various cyclododecenyl groups.
In the general formula of the amine addition salt, the specific aryl group and aralkyl group which R ⁴ can take are an appropriate substituent such as a linear, branched or cyclic lower alkyl group on the aromatic ring. As examples thereof, the same examples as those exemplified as the aryl group and aralkyl group in the description of R ¹ can be given.
[0019]
Preferred examples of amines constituting the amine and amine addition salts of the present invention include decylamine, laurylamine, myristylamine, palmitylamine, stearylamine, behenylamine, oleylamine, monomethyldecylamine, monomethyllaurylamine, monomethylmyristylamine , Monomethylpalmitylamine, monomethylstearylamine, monomethyloleylamine, monoethyldecylamine, monoethyllaurylamine, monoethylmyristylamine, monoethylpalmitylamine, monoethylstearylamine, monoethyloleylamine, monopropyldecylamine, monopropyl Laurylamine, monopropylmyristylamine, monopropylpalmitylamine, monopropylstearylamine, monopropylio Ylamine, dimethyldecylamine, dimethyllaurylamine, dimethylmyristylamine, dimethylpalmitylamine, dimethylstearylamine, dimethyloleylamine, diethyldecylamine, diethyllaurylamine, diethylmyristylamine, diethylpalmitylamine, diethylstearylamine, diethyloleylamine, Methylethyldecylamine, methylethyllaurylamine, methylethylmyristylamine, methylethylpalmitylamine, methylethylstearylamine, methylethyloleylamine, di (hydroxyethyl) decylamine, di (hydroxyethyl) laurylamine, di (hydroxyethyl) Myristylamine, di (hydroxyethyl) palmitylamine, di (hydroxyethyl) stearyl Amines, such as di (hydroxyethyl) oleylamine and the like. Among these, in particular, R ² and R ³ are each a saturated or unsaturated alkyl group having 1 to 8 carbon atoms, and the total number of carbon atoms that R ¹ , R ² and R ³ have is 10 to 24 respectively. The tertiary alkyl amines are particularly suitable.
[0020]
On the other hand, the carboxylic acid constituting the amine addition salt of the present invention is preferably a saturated or unsaturated linear fatty acid having 10 to 20 carbon atoms in R ⁴ . Examples of the carboxylic acid include capric acid, lauric acid, myristic acid, palmitic acid, stearic acid, arachidic acid, behenic acid, oleic acid and the like.
The amine addition salt of the present invention preferably has a molecular weight in the range of 400 to 800.
In addition, in order to improve the strength of flakes and grains in the amine addition salt and prevent fusion that tends to occur at high temperatures in summer, inorganic salts such as phosphates and phosphites are added to the amine addition salt in an amount of 0.1 to 0.1%. About 10% by weight may be included.
In the present invention, the blending amount of bismaleimide is preferably 0.1 to 30 parts by weight with respect to 100 parts by weight of the rubber component. However, if the blending amount is less than 0.1 parts by weight, the blending effect is sufficient. This is because it may not be obtained, and when it exceeds 30 parts by weight, the fracture property tends to decrease. From the same viewpoint, it is preferably 0.5 to 5.0 parts by weight.
Furthermore, the compounding amount of the amine compound is preferably 50 to 400% by weight of the bismaleimide. However, when the amount is less than 50% by weight, a synergistic effect due to the combination with the bismaleimide cannot be obtained. This is because vulcanization is accelerated and rubber is easily burnt. From the same viewpoint, it is preferably 100 to 200% by weight.
[0021]
The vulcanization accelerator that can be used in the present invention is not particularly limited, but preferably MBT (2-mercaptobenzothiazole), DM (dibenzothiazyl disulfide), CBS (N-cyclohexyl-2-). Benzothiazole-based additions such as benzothiazylsulfenamide), TBBS (Nt-butyl-2-benzothiazylsulfenamide), TBSI (Nt-butyl-2-benzothiazylsulfenimide) Examples include sulfur accelerators, guanidine vulcanization accelerators such as DPG (diphenylguanidine), thiuram vulcanization accelerators such as tetraoctyl thiuram disulfide and tetrabenzyl thiuram disulfide, and vulcanization accelerators such as zinc dialkyldithiophosphate. The amount used is preferably 0.1 to 5 parts by weight per 100 parts by weight of the rubber component. More preferably, it is 0.2 to 3 parts by weight.
[0022]
INDUSTRIAL APPLICABILITY The present invention is extremely effective for a sulfur vulcanized rubber composition and a tire obtained by blending a thiazole vulcanization accelerator and / or a thiuram vulcanization accelerator.
In the present invention, natural rubber and synthetic diene rubber can be used. In the case of synthetic diene rubber, cis-1,4-polyisoprene, styrene butadiene copolymer, low cis-1,4-polybutadiene, high cis-1 are used. , 4-polybutadiene, ethylene-propylene-diene copolymer, chloroprene, halogenated butyl rubber, acrylonitrile-butadiene rubber, etc., and natural rubber and synthetic diene rubber can be used not only alone but also blended .
[0023]
Preferred rubbers are natural rubber, cis-1,4-polyisoprene, styrene butadiene copolymer, and polybutadiene.
In addition, it is preferable that the rubber component contains 50% by weight or more of styrene / butadiene copolymer rubber since the improvement effect by the combination of bismaleimide and amines, which is the object of the present invention, becomes most clear.
In the present invention, as the reinforcing filler, at least one of carbon black, silica, calcium carbonate, titanium oxide and the like can be used, and carbon black and silica are preferable.
[0024]
The compounding amount of the reinforcing filler is preferably 20 to 150 parts by weight with respect to 100 parts by weight of the rubber component. This is because if the amount is less than 20 parts by weight, the fracture characteristics and wear resistance of the vulcanizate are not sufficient, and if it exceeds 150 parts by weight, it is not preferable in terms of workability. From the same viewpoint, 25 to 80 parts by weight are more preferable.
Examples of carbon black used as the reinforcing filler include HAF, ISAF, SAF, and the like, and the blending ratio when carbon black and silica are used in combination can be arbitrarily changed according to the blending purpose.
[0025]
In addition to the rubber component, reinforcing filler, bismaleimide, and amine compound, the rubber composition in the present invention includes a silane coupling agent, a vulcanizing agent, a vulcanizing agent, which are usually used in the rubber industry, if necessary. Sulfur accelerators, vulcanization accelerators, antioxidants, ozone degradation inhibitors, anti-aging agents, process oils, zinc white (ZnO), stearic acid, and the like can be blended.
[0026]
Examples of the vulcanizing agent that can be used in the present invention include sulfur and the like, and the amount of these used is 0.1 to 10 parts by weight, preferably 0.5 to 100 parts by weight of the rubber component. -5.0 parts by weight. This is because if the amount is less than 0.1 part by weight, the fracture characteristics and wear resistance of the vulcanized rubber are lowered, and if it exceeds 10 parts by weight, the rubber elasticity tends to be lost.
[0027]
Process oils that can be used in the present invention include, for example, paraffinic, naphthenic, aromatic, etc., and aromatics are used for applications that emphasize fracture characteristics and wear resistance. For applications in which low temperature characteristics are important, naphthenic or paraffinic compounds are preferably used. The amount used is preferably 100 parts by weight or less with respect to 100 parts by weight of the rubber component, because if it exceeds 100 parts by weight, the destructive properties and low heat build-up properties of the vulcanized rubber tend to decrease.
[0028]
The rubber composition of the present invention is obtained by kneading the rubber component, bismaleimide, hydrazide, reinforcing filler and the like using a kneader such as a roll or an internal mixer, and after molding, vulcanizing In addition to tire applications as rubber members such as tire treads, under treads, carcass, sidewalls, and bead parts, it can also be suitably used for applications such as anti-vibration rubber, belts, hoses and other industrial products.
[0029]
【Example】
The present invention will be described more specifically below.
Each compounding component described in Table 1 and Tables 2 to 4 was kneaded and compounded using a 500 ml lab plast mill and a 3-inch roll to obtain an unvulcanized rubber composition. Each rubber composition is subjected to a curast test and a blow point test by the following methods (1) and (2), and the vulcanized tensile test and dynamic viscoelasticity test of these compounded rubbers are performed as described in (3), It measured by the method of (4). These results are shown in Tables 2-4.
[0030]
(1) Curast test: Measured at 145 ° C. using MDR2000 manufactured by Flexis Corporation of the United States.
M _H and M _L are the maximum and minimum values of torque, respectively, and T ₁₀ and T ₉₀ represent the time when the increase in torque due to the vulcanization reaction reaches 10% and 90%, respectively. Each data is expressed as an index with Comparative Example 1, 6 or 8 as 100 respectively.
[0031]
(2) Blow Point Test Using a blow point measuring machine manufactured by Toyo Seiki Co., Ltd., measurement was performed at 170 ° C. under a condition of activation energy of 20 kcal. Each data is expressed as an index with Comparative Example 1, 6 or 8 as 100 respectively. The larger this index is, the larger the blow point value is, indicating that longer vulcanization time is required and the productivity deteriorates.
[0032]
(3) Tensile test 145 ° C. (1) pressurized between 1.5 times corresponding to vulcanization of T ₉₀ obtained in after curing, subjected to tensile tests based on JISK6301-1975 (3 test piece No. use), 300% The elastic modulus at elongation (M ₃₀₀ ) was measured. Similarly, each data is expressed as an index with Comparative Example 1, 6 or 8 as 100.
[0033]
(4) Dynamic Viscoelasticity Test Using a spectrometer (dynamic viscoelasticity measuring tester) manufactured by Toyo Seiki Co., Ltd., E ′ (dynamic storage elastic modulus) at a frequency of 52 Hz, a measurement temperature of 30 ° C., and a strain of 1%. , Tan δ (loss factor) was measured. Similarly, each data is expressed as an index with Comparative Example 1, 6 or 8 as 100.
[0034]
Further, using the rubber compositions of Examples 2, 4, 10, 11, 13, 14, 15 and Comparative Examples 1, 3, 6, 7, 8, and 9 as tread rubber, a tread of 185 / 70R14 size (one layer) Air-borne tires with a structure) were made as prototypes, and the performance of each tire was evaluated in terms of maneuverability during actual vehicle travel.
(5) Maneuverability On a test course with wet water and running on a wet road, use a FF4 door sedan fitted with each new tire to drive an actual vehicle to improve driving performance, braking performance, steering response, and control performance during operation. The test driver comprehensively evaluated each of the tires of Comparative Examples 1, 6 and 8 as control tires.
+1: If the protest driver feels better than the control tire, +2: If the protest driver clearly understands better than the control tire, +3: Skilled among general drivers compared to the control tire When the driver feels good enough to understand +4: When the driver feels better than the control tires [0035]
[Table 1]

[0036]
Noxeller D: DPG
Bismaleimide: N, N ′-(4,4′-diphenylmethane) bismaleimide (BMI-S manufactured by Mitsui Chemical Fine Co., Ltd.)
Compound A: Dimethylstearylamine / stearate Compound B: Stearylamine / stearate Compound C: Dimethylstearylamine
[Table 2]

[0038]
[Table 3]

[0039]
[Table 4]

[0040]
From the above results, in Comparative Examples 1 to 4, by adding bismaleimide, the E 'value could be increased significantly while maintaining the M ₃₀₀ value substantially, and the maneuverability on the wet road surface was improved, but the vulcanization reaction was completed. Time (T ₉₀ ) has increased significantly and productivity has dropped significantly.
In Comparative Example 5, the amine addition salt itself tends to accelerate the vulcanization reaction, but it is 10% or less compared to Comparative Example 1, which is not a great effect.
On the other hand, in Examples 1-9, by using a bismaleimide and an amine compound in combination, the delay in vulcanization is greatly improved and the blow point is greatly improved.
Furthermore, the same synergistic effect was shown also in the type | system | group which increased the silica compounding quantity of Examples 10-15 by using a bismaleimide and an amine compound together.
[0041]
【The invention's effect】
ADVANTAGE OF THE INVENTION According to this invention, workability | operativity is improved, rubber composition suitable for tread rubber etc. with high productivity and high elastic modulus can be provided. Moreover, a pneumatic tire using such a rubber for a tread is excellent in maneuverability.

Claims (10)

The rubber component composed of at least one rubber of natural rubber and synthetic diene rubber, at least one of the bismaleimides represented by the following general formula [Chemical Formula 1], and the following general formula [Chemical Formula 2] A rubber composition comprising at least one amine selected from the group consisting of an amine and an amine addition salt represented by the general formula [Chemical Formula 3].
Record

(In the formula, R represents an aromatic group having 6 to 18 carbon atoms or an alkyl aromatic group having 7 to 24 carbon atoms, and x and y each independently represents an integer of 0 to 3)

(In the formula, R ¹ represents a saturated or unsaturated alkyl group having 8 to 24 carbon atoms or an aralkyl group having 7 to 24 carbon atoms, and R ² and R ³ are a hydrogen atom and a saturated one having 1 to 12 carbon atoms. or unsaturated alkyl group, an aralkyl group having 7 to 12 carbon _{atoms, - (CH 2 O) p} H, - (CH 2 CH 2 O) p H, - (CH (CH 3) CH 2 O) p H, or _{- (CH 2 CH 2 CH 2} O) represents _p H a independently total value of p in R ² and R ³ is any integer of 1 to 4).

(Wherein, R ¹ to R ³ is as defined above, R ⁴ is an alkyl group having a saturated or unsaturated having 6 to 24 carbon atoms, an aryl group having 6 to 24 carbon atoms or aralkyl having 7 to 24 carbon atoms, Represents a group.)   The rubber composition according to claim 1, further comprising at least one of a thiazole vulcanization accelerator and a thiuram vulcanization accelerator. In the general formula of the amine and the amine addition salt, R ² and R ³ each independently represent a saturated or unsaturated alkyl group having 1 to 8 carbon atoms, and for each of the amine and the amine addition salt, R ¹ , R 3 ² and claim 1 or 2 rubber composition according sum of carbon atoms characterized in that it is a 10 to 24 in which R ³ has.   The rubber composition according to claim 1, 2 or 3, wherein the bismaleimide is blended at a ratio of 0.1 to 30 parts by weight with respect to 100 parts by weight of the rubber component.   The rubber composition according to any one of claims 1 to 4, wherein the amine compound is blended in a proportion of 50 to 400% by weight of bismaleimide.   The rubber composition according to claim 1, wherein the bismaleimide is N, N ′-(4,4′-diphenylmethane) bismaleimide. The rubber composition according to any one of claims 1 to 6 , wherein the amine addition salt is dimethylstearylamine stearate or methylstearylamine stearate. The rubber composition according to any one of claims 1 to 7 , wherein 50% by weight or more of the rubber component is styrene / butadiene copolymer rubber. A pneumatic tire, wherein the rubber composition according to any one of claims 1 to 8 is applied as a rubber member. The pneumatic tire according to claim 9, wherein the rubber member is a tread.