JP3629306B2 - V ring - Google Patents

Description

【００２９】
そして、これらのうち、平均粒径５μｍ 以下のＴＦＥ低次重合体が最も好ましく、市販品としてデュポン社製バイダックスＡＲ、旭硝子社製フルオンルブリカントＬ１６９などを挙げることができる。
【００３０】
前記した−Ｃ_ｎ Ｆ_２ｎ−Ｏ−（ｎは１〜４の整数）の主要構造単位を有する平均分子量５×１０^４ 以下のフルオロポリエーテルとしては、下記の化２で表わされるものを例示することができる。
【００３１】
【化２】

【００３２】
このような重合体は、他の配合材料や添加剤に対する親和性（密着性）を向上させるために、イソシアネート基、水酸基、カルボキシル基、エステル等の官能基を含む構造単位を有するものが望ましい。
【００３３】
このようなフルオロポリエーテルの具体例としては、下記の化３で表わされるものが挙げられ、これらを単独使用しても官能基を有しないものと併用してもよい。
【００３４】
【化３】

【００３５】
また、官能基に活性化水素が含まれているフルオロポリエーテルとポリフルオロポリエーテル基を含有しないイソシアネート化合物とを併用してもよく、またイソシアネート基を有するフルオロポリエーテルと、各種のフルオロポリエーテル基を含有しないジアミン類、トリアミン類または各種のフルオロポリエーテル基を含有しないジオール類、トリオール類を併用するなどの方法を採用してもよい。
【００３６】
特に官能基同士が反応して分子量の増大が起こるようなフルオロポリエーテルを組み合わせて使用することが好ましく、このようなものとして、たとえばイソシアネート基を含む単位を有するものと、水酸基を含む単位を有するものとを組み合わせることは同様に好ましいことである。
【００３７】
また、前記したポリフルオロアルキル基含有化合物としては、たとえば下記化４で示されるポリフルオロアルキル基を有するものがあり、炭素数２〜２０で分子量（Ｍｎ）５×１０^４ 以下の具体例としては、下記の化５で表わされるもの（反応性基およびポリフルオロアルキル基を有する化合物と、その反応性基と反応する基を有するエチレン性不飽和化合物との反応物（たとえば、フルオロアルキルアクリレートなど）の重合体や、前記反応性基およびポリフルオロアルキル基を有する化合物とその反応性基と反応する基を有する各種重合体との反応物、または前記化合物の重縮合物など）が挙げられる。
【００３８】
【化４】

【００３９】
【化５】

【００４０】
このようなポリフルオロアルキル基含有化合物は、前記したフルオロポリエーテルと同様に、他の配合材料および添加剤の親和性（密着性）の向上のために、親和性の高い官能基、たとえばイソシアネート基、水酸基、メルカプト基、カルボキシル基、エポキシ基、アミノ基、スルフォン基等を含む単位を有する化合物であることが好ましい。
【００４１】
なお、ポリフルオロアルキル基含有化合物は、単独使用または２種以上併用のいずれでもよく、また、活性化水素を有する反応基を有するポリフルオロアルキル基含有化合物と、ポリフルオロアルキル基を有しないイソシアネート化合物とを併用してもよい。また、イソシアネート基を有するポリフルオロアルキル基含有化合物と、各種のポリフルオロアルキル基を含有しないジアミン類、トリアミン類または各種のポリフルオロアルキル基を含有しないジオール類、トリオール類を併用するなどの方法を採用してもよい。
【００４２】
このような官能基同士の組み合わせは強度増加のうえからも好ましく、具体的には炭素数２〜２０のポリフルオロアルキル基を有し、かつ、水酸基、メルカプト基、カルボキシル基、アミノ基から選ばれる少なくとも１種類を含む含フッ素重合体との組み合わせ、または炭素数２〜２０のポリフルオロアルキル基を有し、かつ、イソシアネート基を含む単位を有する含フッ素重合体と、炭素数２〜２０のポリフルオロアルキル基を有し、さらに活性化水素を有する反応基を含む単位を有する含フッ素重合体との組み合わせを挙げることができる。
【００４３】
特に、上記した低分子量含フッ素重合体のうち、フルオロオレフィン重合体またはフルオロポリエーテルを用いると、潤滑性において優れた結果が得られ、特に平均粒径５μｍ以下のテトラフルオロエチレン重合体を用いると最も望ましい結果を得ることが判明している。
【００４４】
この発明において、フッ素ゴム、熱可塑性フルオロ樹脂および低分子量含フッ素重合体の配合比は、フッ素ゴムと熱可塑性フルオロ樹脂の重量比にて５０：５０から９５：５の範囲が好ましい。なぜならば熱可塑性フルオロ樹脂の配合重量比が５０／１００を越えると、目的の組成物に充分な弾性特性が得られず、５／１００未満では充分な耐摩耗性が得られないからである。
【００４５】
また、フッ素ゴムと熱可塑性フルオロ樹脂の合計１００重量部に対して低分子量含フッ素重合体５〜５０重量部が好ましい。なぜならば、低分子量含フッ素重合体の配合比が５重量部未満では充分な摺動特性が得られず、５０重量部を越えるとゴム状弾性特性が損なわれるからである。
【００４６】
また、上記潤滑性ゴム組成物に対し、３００℃において不溶融な熱硬化性樹脂の硬化粉末、またはガラス転移点が３００℃以上の耐熱性樹脂粉末を添加して耐摩耗性を向上させることができる。
【００４７】
熱硬化性樹脂の粉末としては、フェノール樹脂、エポキシ樹脂などの熱硬化後の微粉末、ガラス転移点が３００℃以上である耐熱性樹脂としては、ポリイミド樹脂、芳香族アラミド樹脂等の微粉末が挙げられる。市販の樹脂粉末のうち、フェノール樹脂の硬化粉砕品としては、鐘紡社製：ベルパールＨ３００、ポリイミド樹脂の硬化粉砕品としては、三笠産業社製：ＰＷＡ２０、芳香族アラミド樹脂の粉砕品としては、旭化成社製：ＭＰ−Ｐ、ガラス転移点Ｔｇが３００℃以上の熱硬化性樹脂粉末としては宇部興産社製：ユーピレックスＳ（Ｔｇ＞５００）などがある。
【００４８】
このような熱硬化性樹脂粉末の粒径は、１〜１５μｍのものがゴム状弾性の維持と混練工程の容易性の点で好ましい。熱硬化性樹脂粉末は、前記必須成分に対して５〜２０重量％添加すればよく、５重量％未満では耐摩耗性向上の効果がなく、２０重量％を越える多量ではゴム弾性が低下するので好ましくない。
【００４９】
なお、この発明の目的を損なわない範囲で上記成分の他に各種添加剤が配合されていてもよい。たとえば、フッ素ゴムの加硫剤としてイソシアネート、有機過酸化物等、ステアリン酸ナトリウム、酸化マグネシウム、水酸化カルシウムなどの酸化防止剤または受酸剤、カーボンなどの帯電防止剤、シリカ、アルミナなどの充填剤、その他金属酸化物、着色剤、難燃剤などを便宜加えてもよいことはいうまでもない。
【００５０】
以上の各種原材料を混合する方法は特に限定するものではなく、通常広く用いられている方法、例えば、主原料になるエラストマー、その他諸原料をそれぞれ個別に順次、または同時にロール混合機その他混合機により混合すればよい。なお、このとき摩擦による発熱を防止する意味で温調器を設けることが望ましい。また、ロール混合機を使用する場合には、仕上げの混合として、ロール間隔を３ｍｍ以下程度に締めて薄通しを行なうとさらに良い。
【００５１】
この発明のＶリングは、成形工程において特に限定した手段を必要とするものではなく、通常のプレス成形方法で一次加硫（１４０〜１７０℃で１０〜３０分、加圧５〜１０ｋｇｆ／ｃｍ^２ ）した後、二次加硫（２００〜３００℃で２〜２０時間、加圧なし）すればよい。
【００５２】
また、この発明においては、前記同様の課題を解決するため、Ｖリングを、アクリロニトリルブタジエンゴムと、テトラフルオロエチレン樹脂粉末と、熱硬化性樹脂の硬化粉末またはガラス転移点が３００℃以上の熱可塑性樹脂粉末を含む潤滑性ゴム組成物で形成したのである。特に、前記硬化粉末または熱可塑性樹脂粉末は、球状の黒鉛であるものが好ましい。
【００５３】
また、上記したテトラフルオロエチレン樹脂粉末は、乳化重合終了後にカーボン材と共沈させて得られる表面にカーボン材が突出したテトラフルオロエチレン樹脂粉末を採用できる。
【００５４】
また、上記したテトラフルオロエチレン樹脂粉末は、テトラフルオロエチレン樹脂とカーボン材を乾式混合して得られる表面にカーボン材が突出したテトラフルオロエチレン樹脂粉末を採用することができる。
【００５５】
また、上記配合重量比が、アクリロニトリルブタジエンゴム１００重量部に対して、テトラフルオロエチレン樹脂粉末１０〜１００重量部、球状黒鉛５〜８０重量部としたのである。
【００５６】
以下に、その詳細を述べる。
この発明におけるアクリロニトリルブタジエンゴム（以下、ＮＢＲと略記する。）は、各種合成法にて合成され、室温においてゴム状弾性を有するものであれば、広範囲のものを例示できる。
【００５７】
ＮＢＲは、ブタジエンとアクリロニトリルの共重合体でアクリロニトリル量を約１５〜５０％に含めることで、その物性を変化させることができる。ニトリル量は、例えば低ニトリル２４％未満、中ニトリル２４〜３０％、中高ニトリル３０〜３６％、高ニトリル３６〜４２％、極高ニトリル４２％を越えるものというように分類できる。耐摩耗性、耐老化性、引張強さを増すために、ニトリル量は多いほうがよいが、ゴム弾性、耐寒性、低温特性を損なわない程度に止めるためには、ニトリル量を約２４％〜４２％の範囲、または約２４％を越え４２％未満の範囲にすることが好ましい。
【００５８】
このＮＢＲの分子量は、通常５万以上のものが望ましく、可及的に高分子量のものが良好な結果を得ることから、より好ましくは７万以上、特に好ましくは１０〜５０万程度のものを用いる。以上の条件を満足する市販品としては、下記のものを例示できる。
【００５９】
日本合成ゴム社製：ＪＳＲ−Ｎ
日本ゼオン社製：ＮＩＰＯＬ
グッドイヤー社製：ＣＨＥＭＩＧＵＭ
また、この発明におけるテトラフルオロエチレン樹脂（以下、ＰＴＦＥと略記する。）粉末とは、懸濁重合法により製造されたモールディングパウダー、乳化重合法により製造されたファインパウダーのいずれを使用してもよいが、加圧・加熱処理された後、粉砕または粉砕後、γ線照射処理または電子線照射処理されたもの、または重合後にγ線照射処理または電子線照射処理された平均粒径２０μｍ以内のものを使用することができる。以上の条件を満足する市販品としては、下記のものを例示できる。
【００６０】
ダイキン工業社製：ルブロンＬ１０
旭硝子社製：フルオンＧ１６３、フルオンＣＤ１、ルーブリカントＬ１６９、Ｌ１８２Ｊ、
三井デュポンフロロケミカル社製：テフロン７Ｊ、
さらに、より好ましいＰＴＦＥ粉末は、図３にその形態を拡大して示すように、ＰＴＦＥ粉末２０の表面に、黒鉛などからなるカーボン材２１が突出し、いわゆる突き刺さった状態にあるものである。このものは、例えばファインパウダー製造の乳化重合終了時に、カーボン材と共沈させて凝析、洗浄、乾燥して得られるＰＴＦＥ粉末である。または、ＰＴＦＥ粉末にカーボン材を乾式混合し、表面に突き刺さった状態にしたものであってもよい。
【００６１】
このようなカーボン材は、一般的な炭素粉から黒鉛まで種々の結晶状態の粉末品であってよいが、黒鉛化による結晶構造に潤滑性が期待されるから、特に黒鉛が好ましい。また、ゴム材に汎用されるストラクチュアの大きいカーボンブラックのＨＡＦ、ＳＡＦ、ＦＥＦまたはＭＴなどであってもよい。
【００６２】
このようなＰＴＦＥ粉末２０は、図３に示したように、黒鉛等からなるカーボン材２１が、全方向（放射状）に突出していることから、ゴム基材２２内での物理的な杭効果があり、しかもゴム基材２２とカーボン材２１の親和性がよいので、ゴム材と通常のＰＴＦＥ粉末を混練したものよりも高強度のものが得られる。
【００６３】
また、この発明に用いる球状黒鉛とは、ピッチから紡糸する工程で副生する球状黒鉛、またはフェノール樹脂を触媒の下でパラフォルムアルデヒドと反応させて球状に重合させたもの、さらにはその後、焼成し粉砕した球状黒鉛が挙げられる。市販の球状黒鉛としては、以下のものが挙げられる。
【００６４】
大阪ガスケミカル社製：メソカーボンビーズ
鐘紡社製：ベルパール、
ユニチカ社製：ユニベックス、
日本カーボン社製：マイクロカーボンビーズ、
この発明におけるＮＢＲと、ＰＴＦＥ粉末の配合重量比は、ＮＢＲ１００重量部に対して、１０〜１００重量部であることが好ましい。なぜなら、ＰＴＦＥ粉末が１０重量部未満では、ＮＢＲに充分な摩擦特性を付与できず、１００重量部を越えて多量に配合すると、ゴム硬度が高くなって弾性特性がなくなり、または機械的強度が極端に低下して実用に耐えない。
【００６５】
また、この発明に用いる熱硬化性樹脂の硬化粉末またはガラス転移点が３００℃以上の熱可塑性樹脂粉末の配合重量比は、ＮＢＲ１００重量部に対して、５〜８０重量部である。その理由は５重量部未満の配合割合では、ＮＢＲに充分な耐摩耗性を付与できず、８０重量部を越えて多量に配合すると、ゴム硬度が高くなって弾性特性がなくなり、または機械的強度が極端に低下して実用に耐えない。このような傾向から、熱硬化製樹脂の硬化粉末またはガラス転移点が３００℃以上の熱可塑性樹脂粉末のより好ましい配合重量比は、ＮＢＲ１００重量部に対して、５〜３０重量部である。また、球状黒鉛の配合重量比は、上記同様の理由により、ＮＢＲ１００重量部に対して、５〜８０重量部である。
【００６６】
なお、この発明には、ゴム用の周知の配合剤または周知の添加剤を配合してもよいのは勿論である。
【００６７】
（１）補強剤：カーボンブラック、シリカ、クレー、炭酸カルシウム、水酸化マグネシウム、水酸化アルミニウム、酸化アルミニウム、タルク、マイカ、カオリン、ベントナイト、シラス、ウォラストナイト、炭化ケイ素、ガラス粉末、カーボン粉末、ボロン繊維、アラミド繊維等、
（２）加硫助剤：亜鉛華、脂肪酸等、
（３）加硫促進剤：グアニジン類、イオウ類、アルデヒド−アミン類、亜鉛類等、
（４）可塑剤：ジメチルフタレート、ジオクチルフタレート等、
（５）老化紡糸剤：アミン類、フエノール類等、
（６）その他、酸化防止剤、紫外線吸収剤、難燃剤、着色剤など、
さらに、成形時の離型性および表面の非粘着性を向上させるために、オイル、ワックス、グリース類を添加してもよい。その配合量は、ゴム成形品の機械的強度に影響を及ぼさない程度、すなわちＮＢＲ１００重量部に対して２〜２０重量部であることが好ましく、より好ましくは５〜１０重量部である。
【００６８】
固体潤滑剤として、ＰＴＦＥ以外に溶融フッ素樹脂であるテトラフルオロエチレン−エチレン共重合体（ＥＴＦＥ）、テトラフルオロエチレン−パーフルオロアルキルビニルエーテル共重合体（ＰＦＡ）、テトラフルオロエチレン−ヘキサフルオロプロピレン共重合体（ＦＥＰ）などを添加してもよい。
【００６９】
以上の各種原材料を混合する方法は特に限定するものではなく、通常広く用いられている方法、例えば、主原料になるＮＢＲ、その他の充填剤を個別に順次混合または一括してロール混合機、プロペラ混合機、ニーダ混合機その他の混合機で混合すればよい。なお、このとき摩擦による発熱を防止する意味で温調器を設けることが望ましい。また、ロール混合機を使用する場合には、仕上げ混合として、ロール間隔を３ｍｍ以下として薄通しを行なうことが好ましい。
【００７０】
【実施例】
実施例および比較例で用いた原材料を一括して示すと以下のとおりである。なお、各成分の配合割合は重量％であるが、（３）〜（７）に示す原材料については（１）、（２）に示す原材料の総重量１００に対する重量部で示した。
【００７１】
（１）フッ化ビニリデン−フルオロプロピレン共重合体（旭モンテ社製：テクノフロンＦＯＲ４２０）
（２）テトラフルオロエチレン−エチレン共重合体〔ＥＴＦＥ〕（旭硝子社製：アフロンＣＯＰ）
（３）低分子量含フッ素重合体〔低分子量ＴＦＥ〕（旭硝子社製：ルーブリカントＬ１６９）
（４）低分子量含フッ素重合体（フルオロポリエーテル）〔低分子量ＦＥＰ〕（日本エニモント社製：フォンブリンＺ−ＤＩＳＯＣ）
（５）カーボン（ファンデルビルト社製：ＭＴカーボン）
（６）ステアリン酸ナトリウム （一般工業材）
（７）酸化マグネシウム〔ＭｇＯ〕 （一般試薬）
（８）水酸化カルシウム〔Ｃａ（ＯＨ）_２ 〕 （一般試薬）
（９）フェノール樹脂 （カネボウ社製：ベルパールＨ３００）
（１０）ニトリル−ブタジエン系共重合体〔ＮＢＲ〕（一般工業材 硬度ＪＩＳ−Ａ７０）
（１１）クロロプレン系共重合体〔クロロプレンゴム〕（一般工業材 硬度ＪＩＳ−Ａ７０）
〔実施例１〜４、比較例１〜５〕
ロール間隔５〜１０ｍｍに調整したロール混合機にフッ素ゴム（１）を巻きつけ、表１に示した割合で順次、ＭＴカーボン、ステアリン酸ナトリウム、ＭｇＯ、Ｃａ（ＯＨ）_２ を加えて混練した。その後、ロール間隔を１ｍｍに調整し、素練りを約１０回行なった。なお、この時の摩擦熱を防止する目的で、常時ロール内に冷却水を通し、ロール温度を６０℃以下に保った。次に、冷却水を止め、ロール内にスチームを通してゴム温度が７０℃以上、９０℃以下になるように調整し、その後、ロール間隔を５〜１０ｍｍ程度に戻し、低分子量含フッ素重合体を少量ずつ添加しながら表１に示す配合割合で混練した。その後、再びロール間隔を１ｍｍに狭めて素練りを約１０回行なった。
【００７２】
以上の工程で得られたコンパウンドにおける１５０×１５０×ｔ１（ｍｍ）シートを、一次加硫（１７０℃、１０分、プレス圧７ｋｇｆ／ｃｍ^２ ）および二次加硫（２３０℃、１６時間、フリー）を行なった。このようにして加硫した各試験片について、摩擦・摩耗特性、非粘着性、一般特性、実機耐久性を求めた。各試験方法はつぎのとおりである。
【００７３】
（ａ）摩擦・摩耗試験：
内径φ１７ｍｍ、外径φ２１ｍｍのリング状シート試験片をφ１７×φ２１×ｔ１０（ｍｍ）のアルミ合金製リングに接着して摩擦試験片とした。相手材は軸受鋼（ＳＵＪ２）の研磨品とし、スラスト型摩擦試験機にて評価した。試験条件は、周速１２８ｍ／分、面圧３．５ｋｇｆ／ｃｍ^２ とし、試験開始当初とその後の摩擦係数と摩耗係数 （×１０^−１０ ｃｍ^３ ／ｋｇｆ・ｍ）を表中に示した。
【００７４】
（ｂ）非粘着性試験：
各試験片の水に対する接触角をゴニオメータ式接触角測定器で測定し、接触角の大きいものほど非粘着性は良いと判断し、結果を表中に併記した。
【００７５】
（ｃ）機械的特性：
得られたシート状試験片に対してＪＩＳ−Ｋ６３０１に準拠し、引張り強度、伸び、硬度（ＪＩＳ−Ａ）を調べ、結果を表中に併記した。
【００７６】
（ｄ）実機耐久性試験：
軸径（内径）φ３２ｍｍ、外径φ４８ｍｍ、幅１０ｍｍのＶリング形状の試験片を、雰囲気温度を４０℃に設定した恒温槽の中で、図２に示した状態にＶリングを装着した試験機にて、軸５を毎分２００回転の速度で連続５００時間運転した。この場合、Ｖリング１のリップ４が摺接するハウジング７は、軸受鋼（ＳＵＳＪ２）で形成されたものである。
【００７７】
上記試験の結果は、Ｖリング１の摩耗量が０．００１ｇ以下を〇印、摩耗量０．００１ｇを越え０．００５ｇ未満を△印、摩耗量０．００５ｇ以上を×印の３段階に評価し、これを表中に併記した。
【００７８】
【表１】

【００７９】
【表２】

【００８０】
表２の結果から明らかなように、フッ素ゴム単独の組成物、またはフッ素ゴムにＥＴＦＥまたは低分子量ＴＦＥを添加した組成物からなる比較例の試験片は、摩擦係数が高く、摺動特性に耐久性がなかった。また、ニトリルゴム、クロロプレンゴムからなる試験片でも同様の結果であった。
【００８１】
これに対して、全ての条件を満足する実施例１〜４の試験片は、非粘着性、低摩擦特性および耐摩耗性の全てを兼ね備えており、５００時間の連続使用に耐えることがわかる。
【００８２】
次に、実施例５〜１３および比較例６〜１１に用いた合成ゴムの基本組成を以下に示す。
【００８３】
［ＮＢＲ基礎配合Ａ］（高ニトリルタイプ、ニトリル量３６〜４２％）
日本合成ゴム社製：ＪＳＲ２２０Ｓ １００重量部
ステアリン酸ナトリウム：一般工業材 １ 〃
カーボンブラック：ＦＥＦ ３０ 〃
加硫促進剤１：大内新興化学工業社製：ＴＴ ２ 〃
加硫促進剤２：大内新興化学工業社製：Ｍ ２ 〃
加硫助剤：酸化亜鉛（活性亜鉛華） １０ 〃
加硫剤：イオウ １ 〃
［ＮＢＲ基礎配合Ｂ］（中ニトリルタイプ、ニトリル量２４〜３０％）
日本合成ゴム社製：ＪＳＲ２４０Ｓ １００重量部
ステアリン酸ナトリウム：一般工業材 １ 〃
カーボンブラック：ＦＥＦ ３０ 〃
加硫促進剤１：大内新興化学工業社製：ＴＴ ２ 〃
加硫促進剤２：大内新興化学工業社製：Ｍ ２ 〃
加硫助剤：酸化亜鉛（活性亜鉛華） １０ 〃
加硫剤：イオウ １ 〃
［潤滑剤］
（１）黒鉛共沈ＰＴＦＥ〔ＰＴＦＥ−１〕
乳化重合にて重合完了後に平均粒径６μｍの黒鉛と７：３の重量比で共沈させ、凝析、洗浄して得られたものである。
（２）黒鉛とのドライブレンドＰＴＦＥ〔ＰＴＦＥ−２〕
旭硝子社製ＰＴＦＥ（ルーブリカントＬ１８２Ｊ）を平均粒径６μｍの黒鉛と７：３の重量比にてヘンシェルミキサーでドライブレンドしたものである。
（３）ＰＴＦＥ〔ＰＴＦＥ−３〕
旭硝子社製：ＰＴＦＥルーブリカントＬ１８２Ｊ
（４）ＥＴＦＥ（旭硝子社製：アフロンＣＯＰ Ｚ８８２０）
（５）球状黒鉛（鐘紡社製：ベルパールＣ２０００）
（６）シリコーンオイル（信越シリコーン社製：ＫＦ９６−３００）。
【００８４】
〔実施例５〜１３、比較例６〜１０〕
ロール間隔５〜１０ｍｍ程度に調整したロール混合機に、ＮＢＲ（２２０Ｓ）を巻き付け、基礎配合ＡまたはＢに示した割合で無機充填剤、老化防止剤、カーボン、イオウ、加硫促進剤を順次混合し、最後に表３または表４に示した割合でＰＴＦＥおよび他の充填剤を混練した。
【００８５】
その後、ロール間隔を１ｍｍに調整し、薄通しを１０回行なった。なお、このときの摩擦熱を防止する目的で、常時ロール内に冷却水を通し、ロール温度を６０℃以下に保った。次に、冷却水を止め、ロール内にスチームを通してゴム温度が７０℃以上９０℃以下になるように調整し、その後、ロール間隔を１ｍｍで薄通しを１０回行ない、それぞれ１０ｋｇのコンパウンドを得た。
【００８６】
以上のようにして得られたコンパウンドを縦３００ｍｍ、横３００ｍｍ、厚さ１ｍｍの金型でプレス成形し、１次加硫（１６０℃、１０分、プレス圧１２０ｋｇｆ／ｃｍ^２ ）および２次加硫（１５０℃、４時間、フリー）を行なった。このようにして加硫を終えたシート状の各試験片について、摩擦・摩耗特性、非粘着性、機械的特性を求めた。
【００８７】
また、実際のシール試験片として、図１に示すようなＶリングを形成し、実機試験行なった。各試験方法は、前記試験方法（ａ）で試験条件を、周速１．０ｍ／分、面圧３．０ｋｇｆ／ｃｍ^２ 、測定を試験開始当初、５０時間後、１００時間後に変更したこと以外は、前記した（ａ）〜（ｄ）の通りである。これらの結果は、表５または表６に示した。
【００８８】
【表３】

【００８９】
【表４】

【００９０】
【表５】

【００９１】
【表６】

【００９２】
なお、表に示される数値の上限値以上で下限値以下、または上限値を越え下限値未満の配合、特性値等として最も適したシール成形体を提供するように、適宜に選択してもよい。
【００９３】
〔比較例１１〕
比較例６と同様にして、ＮＢＲ基礎配合Ｂのコンパウンドを作成し、試験片を成形した。この試験片に対してゴム用市販コーティング剤（日本アチソン社製：エムラロン３４５）をスプレーコーティング法にて約１５μｍの被膜を形成した。コーティング後、電気炉にて８０℃で１時間乾燥し、さらに焼成して試験片を完成させた。
【００９４】
得られた試験片に対して、比較例６と全く同様の試験にて評価し、結果を表６中に併記した。
【００９５】
表５および表６の結果からも明らかなように、一般的なＮＢＲの配合物だけの比較例６では摩擦係数が高く、摩耗量が大きかった。また、ＮＢＲにＰＴＦＥを添加した７、８は、いずれも摩擦係数がゴム基材より若干低くなったが、摩耗特性が充分でなかった。また、球状黒鉛を配合した比較例９では、耐摩耗性が改善されたが、摩擦係数が約０．８と大きく、実機試験でも追従性が徐々に劣化した。シリコーンオイルを配合した比較例１０は、機械的強度が著しく低下しており、摩耗特性も極めて悪かった。なお、いずれの比較例でも実機試験での摩耗が多く、トナーの漏れが確認された。
【００９６】
一方、カーボン材が表面に突出した粉体状のＰＴＦＥと球状黒鉛を併用して添加した実施例１〜１２は、機械的強度の低下が少なく、低摩擦係数および耐磨耗性に優れた特性であり、実機試験でも安定した低摩擦・低摩耗特性が確認できた。また、実施例１３は、ＰＴＦＥと共に球状黒鉛を添加したものであるため、比較例に比べて低摩擦・低摩耗特性であり、他の実施例のように使用に耐えるものであった。
【００９７】
【効果】
この発明は以上説明したように、Ｖリングを、フッ素ゴムと熱可塑性フルオロ樹脂と所定分子量の低分子量含フッ素重合体を所定割合で配合した潤滑性ゴム組成物で形成したので、このものが非粘着性、低摩擦特性および耐摩耗性の全てを兼ね備えたものとなり、長時間の連続使用に耐えるものとなる利点がある。
【００９８】
また、Ｖリングを、アクリロニトリルブタジエンゴムとテトラフルオロエチレン樹脂粉末と球状黒鉛を含んだ潤滑性ゴム組成物で形成したＶリングとした発明においても、ＮＢＲ材料本来の充分なゴム特性を有すると共に、低摩擦特性および耐摩耗性を兼ね備えたものとなる利点がある。
【００９９】
したがって、この発明のＶリングは、ゴム特性を生かしたシール性を充分に発揮すると共に、長寿命で安定した低摩擦特性および耐摩耗性に優れたシール部材となるのである。
【図面の簡単な説明】
【図１】Ｖリングを一般的形状を示す正面図
【図２】Ｖリングの使用状態を説明する縦断面図
【図３】ゴム基材中のテトラフルオロエチレン樹脂を示す模式図
【符号の説明】
１ Ｖリング
２ リング本体
３ ヒンジ部
４ リップ
５ 軸
６ 転がり軸受
７ ハウジング[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a V-ring that prevents leakage or intrusion of dust, oil or the like.
[0002]
[Prior art]
In general, a seal ring called a V-ring having a V-shaped cross section made of rubber in which a conical lip is connected to one end of a ring body is known.
[0003]
The shape of such a V-ring 1 will be described with reference to FIGS. 1 and 2. This V-ring 1 has a conical shape through a small-diameter hinge portion 3 at one end of a ring body 2 having a trapezoidal cross section in the axial direction. The lip 4 is integrally formed.
[0004]
As shown in FIG. 2, when such a V ring 1 is used, when it is fitted to the shaft 5 and used as a seal ring of the rolling bearing 6, for example, the V ring 1 rotates together with the shaft 5, and the ring body 2 moves to the lip 4 The shaft 5 is sealed while supporting and prevents dust and splashes from entering the bearing, and the grease in the bearing 6 is not leaked to the outside.
[0005]
Even if such a V-ring rotates eccentrically when the shaft 5 rotates or the shaft 5 is tilted due to poor centering accuracy of the shaft, the angle of the hinge 3 changes and the lip 4 A seal function is exhibited by being in close contact with the housing 7 of the bearing 5 in an elastic manner.
[0006]
As such a conventional V-ring molding material, for example, nitrile rubber, chloroprene rubber, fluorine rubber and the like have been used.
[0007]
[Problems to be solved by the invention]
However, as described above, a V-ring made of a conventional material cannot satisfy at least one of non-adhesiveness, low friction characteristics, and wear resistance, and can withstand long-term continuous use. There is a problem that it is not possible.
[0008]
Therefore, the object of the present invention is to solve the above-mentioned problems and to sufficiently withstand continuous use for a long time, assuming that the V-ring has all of non-adhesiveness, low friction characteristics and wear resistance. It is to be.
[0009]
[Means for Solving the Problems]
In order to solve the above-mentioned problems, in the present invention, in a V-shaped V-ring having a conical lip connected to one end of a ring body, the V-ring is a first essential component and a second essential component. Thermoplastic fluororesin as a component and number average molecular weight 5 × 10 as a third essential component ⁴ It comprises the following low molecular weight fluoropolymer, the blending weight ratio of the first essential component and the second essential component is in the range of 50:50 to 95: 5, and the first essential component and the second essential component The blending amount of the third essential component with respect to 100 parts by weight in total was 5 to 50 parts by weight.
[0010]
The fluoro rubber as the first essential component includes tetrafluoroethylene-propylene copolymer, vinylidene fluoride-hexafluoropropylene copolymer, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene copolymer, fluorosilicone-based fluorine. One or more fluororubbers selected from the group consisting of rubber and perfluoro fluororubber can be employed.
[0011]
The thermoplastic fluororesin as the second essential component is selected from the group consisting of a tetrafluoroethylene-ethylene copolymer, a tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer, and a tetrafluoroethylene-hexafluoropropylene copolymer. One or more selected polymers can be employed.
[0012]
Further, the low molecular weight fluorine-containing polymer as the third essential component may be one or more polymers selected from the group consisting of tetrafluoroethylene polymers, fluoropolyethers and polyfluoroalkyl group-containing compounds. . Moreover, a tetrafluoroethylene polymer having an average particle size of 5 μm or less can be adopted as the low molecular weight fluorine-containing polymer as the third essential component.
[0013]
The lubricating rubber composition may further contain 5 to 20% by weight of a thermosetting resin cured powder or a thermoplastic resin powder having a glass transition point of 300 ° C. or higher.
[0014]
Alternatively, a V-ring is a lubricating rubber composition in which acrylonitrile butadiene rubber is used as a base material and tetrafluoroethylene resin powder and thermosetting resin cured powder or thermoplastic resin powder having a glass transition point of 300 ° C. or higher are blended. It was formed.
[0015]
A spherical graphite material can be adopted as the cured powder of the thermosetting resin or the thermoplastic resin powder having a glass transition point of 300 ° C. or higher.
[0016]
As the tetrafluoroethylene resin powder, a tetrafluoroethylene resin powder having a carbon material protruding on the surface obtained by coprecipitation with a carbon material after completion of emulsion polymerization can be adopted.
[0017]
Further, as the tetrafluoroethylene resin powder, a tetrafluoroethylene resin powder in which a carbon material protrudes on a surface obtained by dry-mixing a tetrafluoroethylene resin and a carbon material can be adopted.
[0018]
Further, the blending weight ratio of the components is 10 to 100 parts by weight of tetrafluoroethylene resin powder, 100% by weight of acrylonitrile butadiene rubber, a cured powder of thermosetting resin, or a thermoplastic resin powder having a glass transition point of 300 ° C. or higher. The V ring was 5 to 80 parts by weight.
[0019]
DETAILED DESCRIPTION OF THE INVENTION
First, the fluororubber in this invention is a polymer or copolymer of unit monomers containing an average of one or more fluorine atoms, and has a glass transition point of room temperature or less and has rubber-like elasticity at room temperature. If it is, it will not specifically limit but a wide range can be illustrated.
[0020]
For the fluororubber, polymerization methods such as bulk polymerization, suspension polymerization, emulsion polymerization, solution polymerization, catalyst polymerization, ionizing radiation polymerization, and redox polymerization can be adopted at the production stage. The number average molecular weight (Mn) of such a fluororubber is usually 5 × 10 ⁴ The above are preferable, and those having a high molecular weight as much as possible will give good results, so Mn 7 × 10 ⁴ Above, particularly preferably 10 × 10 ⁴ ~ 25x10 ⁴ It is more preferable to use a material having a degree.
[0021]
As a commercial product of fluororubber satisfying the above conditions, tetrafluoroethylene-propylene copolymer, manufactured by Asahi Glass Co., Ltd .: Aflas, vinylidene fluoride-hexafluoropropylene copolymer, manufactured by DuPont, Showa Denko Co., Ltd .: Viton , Made by Montefluos, a vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene copolymer: Technoflon, made by Dow Corning, a fluorosilicone elastomer: Silastic LS, made by Firestone, a phosphazene fluororubber: PNF, Daikin Kogyo Co., Ltd., which is a perfluoro fluororubber: Daiel Perflo, etc.
[0022]
The thermoplastic fluororesin (fluororesin) in this invention includes tetrafluoroethylene-ethylene copolymer (hereinafter abbreviated as ETFE), tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (hereinafter abbreviated as PFA), tetrafluoro One or more polymers selected from the group consisting of ethylene-hexafluoropropylene copolymers (hereinafter abbreviated as FEP) are preferred.
[0023]
Other usable thermoplastic fluororesins include tetrafluoroethylene-hexafluoropropylene-perfluoroalkyl vinyl ether copolymer (hereinafter abbreviated as EPE), trifluorochloroethylene polymer (hereinafter abbreviated as CTFE), and trifluoro. Examples include chloroethylene-ethylene copolymer (hereinafter abbreviated as ECTFE), polyvinyl fluoride (hereinafter abbreviated as PVF), and polyvinylidene fluoride (hereinafter abbreviated as PVDF).
[0024]
As the above-mentioned thermoplastic fluororesin, various polymerization methods such as catalyst emulsion polymerization, suspension polymerization, catalyst solution polymerization, gas phase polymerization, and ionizing radiation irradiation polymerization can be adopted at the production stage. Molecular weight (Mn) is 5 × 10 ⁴ The following are desirable: 5 × 10 ³ Over 2 × 10 ⁴ The following are particularly desirable:
[0025]
As representative examples corresponding to the above conditions, PFA MP10 manufactured by Mitsui / DuPont Fluorochemical Co., which is the above-mentioned PFA, Teflon FEP100 manufactured by Mitsui / DuPont Fluorochemical Co., Ltd., Aflon COP manufactured by Asahi Glass Co., Ltd., which is ETFE, and the like. It is done.
[0026]
The composition obtained by mixing the above-described fluororubber and thermoplastic fluororesin has characteristics as an elastic body. In the present invention, the low molecular weight fluorine-containing polymer is blended in order to give such an elastic body even better sliding properties.
[0027]
Here, as the low molecular weight fluorine-containing polymer, tetrafluoroethylene (TFE), main structural unit -C _n F _2n Fluoropolyether having —O— (n is an integer of 1 to 4), a polyfluoroalkyl group-containing compound (2 to 20 carbon atoms) having a main structural unit represented by the following formula 1, molecular weight (Mn) 5 × 10 ⁴ The following are mentioned, but in order to give better sliding properties, the molecular weight is 5 × 10 ³ The following are particularly preferred:
[0028]
[Chemical 1]

[0029]
Of these, a TFE low-order polymer having an average particle size of 5 μm or less is most preferred, and examples of commercially available products include DuPont Vidax AR and Asahi Glass Co., Ltd. Fullon Lubricant L169.
[0030]
-C mentioned above _n F _2n Average molecular weight 5 × 10 having a main structural unit of —O— (n is an integer of 1 to 4) ⁴ As the following fluoropolyether, those represented by the following chemical formula 2 can be exemplified.
[0031]
[Chemical formula 2]

[0032]
Such a polymer preferably has a structural unit containing a functional group such as an isocyanate group, a hydroxyl group, a carboxyl group, or an ester in order to improve the affinity (adhesiveness) to other compounding materials and additives.
[0033]
Specific examples of such a fluoropolyether include those represented by the following chemical formula 3, which may be used alone or in combination with those having no functional group.
[0034]
[Chemical 3]

[0035]
Moreover, you may use together the fluoropolyether in which the activated hydrogen is contained in the functional group, and the isocyanate compound which does not contain a polyfluoropolyether group. Moreover, the fluoropolyether which has an isocyanate group, and various fluoropolyethers A method of using diamines not containing a group, triamines, diols not containing various fluoropolyether groups, and triols in combination may be employed.
[0036]
In particular, it is preferable to use a combination of fluoropolyethers that cause functional groups to react with each other and increase the molecular weight. As such, for example, those having units containing isocyanate groups and units containing hydroxyl groups are used. Combining things with them is likewise preferred.
[0037]
Moreover, as the above-mentioned polyfluoroalkyl group-containing compound, for example, there is a compound having a polyfluoroalkyl group represented by the following chemical formula 4 having 2 to 20 carbon atoms and a molecular weight (Mn) of 5 × 10 ⁴ Specific examples of the following are compounds represented by the following chemical formula 5 (reaction product of a compound having a reactive group and a polyfluoroalkyl group and an ethylenically unsaturated compound having a group that reacts with the reactive group (for example, , Fluoroalkyl acrylate, etc.), a reaction product of a compound having a reactive group and a polyfluoroalkyl group and various polymers having a group reactive with the reactive group, or a polycondensate of the compound ).
[0038]
[Formula 4]

[0039]
[Chemical formula 5]

[0040]
Such a polyfluoroalkyl group-containing compound is a functional group having a high affinity, such as an isocyanate group, in order to improve the affinity (adhesion) of other compounding materials and additives, like the above-mentioned fluoropolyether. And a compound having a unit containing a hydroxyl group, a mercapto group, a carboxyl group, an epoxy group, an amino group, a sulfone group, or the like.
[0041]
The polyfluoroalkyl group-containing compound may be used alone or in combination of two or more. The polyfluoroalkyl group-containing compound having a reactive group having activated hydrogen and the isocyanate compound not having a polyfluoroalkyl group And may be used in combination. In addition, a method of using a polyfluoroalkyl group-containing compound having an isocyanate group together with various diamines not containing a polyfluoroalkyl group, triamines or various diols not containing a polyfluoroalkyl group, triols, etc. It may be adopted.
[0042]
Such a combination of functional groups is also preferable from the viewpoint of increasing the strength. Specifically, the functional group has a polyfluoroalkyl group having 2 to 20 carbon atoms, and is selected from a hydroxyl group, a mercapto group, a carboxyl group, and an amino group. A combination with a fluorine-containing polymer containing at least one kind, or a fluorine-containing polymer having a polyfluoroalkyl group having 2 to 20 carbon atoms and a unit containing an isocyanate group, and a polycrystal having 2 to 20 carbon atoms Examples thereof include a combination with a fluoropolymer having a unit having a fluoroalkyl group and a reactive group having activated hydrogen.
[0043]
In particular, when a fluoroolefin polymer or a fluoropolyether is used among the low molecular weight fluorine-containing polymers described above, excellent results are obtained in lubricity, and particularly when a tetrafluoroethylene polymer having an average particle size of 5 μm or less is used. It has been found that the most desirable results are obtained.
[0044]
In this invention, the blending ratio of the fluororubber, the thermoplastic fluororesin and the low molecular weight fluoropolymer is preferably in the range of 50:50 to 95: 5 in terms of the weight ratio of the fluororubber to the thermoplastic fluororesin. This is because if the blending weight ratio of the thermoplastic fluororesin exceeds 50/100, sufficient elastic properties cannot be obtained for the target composition, and if it is less than 5/100, sufficient abrasion resistance cannot be obtained.
[0045]
Moreover, 5-50 weight part of low molecular weight fluoropolymers are preferable with respect to a total of 100 weight part of fluororubber and thermoplastic fluororesin. This is because if the blending ratio of the low molecular weight fluoropolymer is less than 5 parts by weight, sufficient sliding properties cannot be obtained, and if it exceeds 50 parts by weight, the rubbery elastic properties are impaired.
[0046]
In addition, it is possible to improve the wear resistance by adding a hardened thermosetting resin powder that is not melted at 300 ° C. or a heat resistant resin powder having a glass transition point of 300 ° C. or higher to the lubricating rubber composition. it can.
[0047]
The thermosetting resin powder is a fine powder after thermosetting such as phenol resin or epoxy resin, and the heat-resistant resin having a glass transition point of 300 ° C. or higher is a fine powder such as polyimide resin or aromatic aramid resin. Can be mentioned. Among the commercially available resin powders, as a cured pulverized product of phenol resin, Kanebo Co., Ltd .: Bell Pearl H300, as a cured pulverized product of polyimide resin, manufactured by Mikasa Sangyo Co., Ltd .: PWA20, as a pulverized product of aromatic aramid resin, Asahi Kasei Company-made: MP-P, and thermosetting resin powder having a glass transition point Tg of 300 ° C. or higher include Upyorex Corporation: Upilex S (Tg> 500).
[0048]
The particle size of such a thermosetting resin powder is preferably 1 to 15 μm from the viewpoint of maintaining rubber-like elasticity and the ease of the kneading process. The thermosetting resin powder may be added in an amount of 5 to 20% by weight based on the essential components, and if it is less than 5% by weight, there is no effect of improving the wear resistance. It is not preferable.
[0049]
Various additives may be blended in addition to the above components as long as the object of the present invention is not impaired. For example, fluorinated rubber vulcanizing agents such as isocyanates, organic peroxides, antioxidants or acceptors such as sodium stearate, magnesium oxide, calcium hydroxide, antistatic agents such as carbon, silica, alumina, etc. Needless to say, agents, other metal oxides, colorants, flame retardants and the like may be added for convenience.
[0050]
The method for mixing the above-mentioned various raw materials is not particularly limited, and is usually a widely used method, for example, an elastomer as a main raw material, and other raw materials individually or sequentially by a roll mixer or other mixer. What is necessary is just to mix. At this time, it is desirable to provide a temperature controller in order to prevent heat generation due to friction. Moreover, when using a roll mixer, it is better to perform thinning by tightening the roll interval to about 3 mm or less as finishing mixing.
[0051]
The V-ring of the present invention does not require any means specifically limited in the molding process, and is subjected to primary vulcanization by a normal press molding method (10 to 30 minutes at 140 to 170 ° C., pressure 5 to 10 kgf / cm). ² ), Followed by secondary vulcanization (at 200 to 300 ° C. for 2 to 20 hours without pressure).
[0052]
Further, in the present invention, in order to solve the same problem as described above, the V ring is made of acrylonitrile butadiene rubber, tetrafluoroethylene resin powder, a cured powder of a thermosetting resin, or a thermoplastic having a glass transition point of 300 ° C. or higher. It was formed of a lubricating rubber composition containing resin powder. In particular, the cured powder or the thermoplastic resin powder is preferably spherical graphite.
[0053]
Moreover, the tetrafluoroethylene resin powder which the carbon material protruded on the surface obtained by coprecipitating with a carbon material after completion | finish of emulsion polymerization can be employ | adopted for the above-mentioned tetrafluoroethylene resin powder.
[0054]
Moreover, the tetrafluoroethylene resin powder which the carbon material protruded on the surface obtained by dry-mixing tetrafluoroethylene resin and a carbon material can be employ | adopted for the above-mentioned tetrafluoroethylene resin powder.
[0055]
Further, the blending weight ratio is 10 to 100 parts by weight of tetrafluoroethylene resin powder and 5 to 80 parts by weight of spherical graphite with respect to 100 parts by weight of acrylonitrile butadiene rubber.
[0056]
The details will be described below.
The acrylonitrile butadiene rubber (hereinafter abbreviated as NBR) in the present invention is exemplified by a wide range of materials as long as it is synthesized by various synthesis methods and has rubber-like elasticity at room temperature.
[0057]
NBR is a copolymer of butadiene and acrylonitrile, and its physical properties can be changed by including acrylonitrile in an amount of about 15 to 50%. The amount of nitrile can be classified, for example, as low nitrile less than 24%, medium nitrile 24-30%, medium high nitrile 30-36%, high nitrile 36-42%, and extremely high nitrile 42%. In order to increase wear resistance, aging resistance, and tensile strength, it is better to have a large amount of nitrile. However, in order to stop rubber elasticity, cold resistance, and low temperature characteristics from being impaired, the amount of nitrile is about 24% to 42%. % Range, or more than about 24% and less than 42%.
[0058]
The molecular weight of this NBR is usually desirably 50,000 or more, and since a high molecular weight as much as possible obtains good results, it is more preferably 70,000 or more, particularly preferably about 100,000 to 500,000. Use. The following can be illustrated as a commercial item which satisfies the above conditions.
[0059]
Nippon Synthetic Rubber Co., Ltd .: JSR-N
Nippon Zeon: NIPOL
Goodyear, Inc .: CHEMIGUM
The tetrafluoroethylene resin (hereinafter abbreviated as PTFE) powder in the present invention may be either a molding powder produced by a suspension polymerization method or a fine powder produced by an emulsion polymerization method. Is subjected to γ-ray irradiation treatment or electron beam irradiation treatment after pressurization and heat treatment, pulverization or pulverization, or γ-ray irradiation treatment or electron beam irradiation treatment after polymerization and within an average particle size of 20 μm Can be used. The following can be illustrated as a commercial item which satisfies the above conditions.
[0060]
Daikin Industries, Ltd .: Lubron L10
Asahi Glass Co., Ltd .: Fullon G163, Fullon CD1, Lubricant L169, L182J,
Made by Mitsui DuPont Fluorochemicals: Teflon 7J
Further, a more preferable PTFE powder is a so-called stabbed state in which a carbon material 21 made of graphite or the like protrudes from the surface of the PTFE powder 20 as shown in an enlarged form in FIG. This is a PTFE powder obtained by coprecipitation with a carbon material, coagulation, washing and drying at the end of emulsion polymerization in the production of fine powder, for example. Alternatively, a PTFE powder may be dry mixed with a carbon material and pierced on the surface.
[0061]
Such a carbon material may be a powder product in various crystal states from general carbon powder to graphite, but graphite is particularly preferable since lubricity is expected in the crystal structure by graphitization. Further, it may be a carbon black HAF, SAF, FEF or MT, which is widely used for rubber materials and has a large structure.
[0062]
As shown in FIG. 3, such a PTFE powder 20 has a physical pile effect in the rubber base material 22 because the carbon material 21 made of graphite or the like protrudes in all directions (radially). In addition, since the affinity between the rubber base material 22 and the carbon material 21 is good, a material having higher strength than that obtained by kneading the rubber material and ordinary PTFE powder can be obtained.
[0063]
Further, the spherical graphite used in the present invention is a spherical graphite produced as a by-product in the process of spinning from pitch, or a product obtained by reacting a phenol resin with paraformaldehyde under a catalyst to polymerize into a spherical shape, and then firing it. And then pulverized spherical graphite. Examples of commercially available spherical graphite include the following.
[0064]
Osaka Gas Chemical Co., Ltd .: Mesocarbon beads
Made by Kanebo: Bell Pearl,
Unitika: Universex,
Nippon Carbon Co., Ltd .: micro carbon beads,
The blending weight ratio of NBR and PTFE powder in this invention is preferably 10 to 100 parts by weight with respect to 100 parts by weight of NBR. This is because if the PTFE powder is less than 10 parts by weight, sufficient frictional properties cannot be imparted to NBR, and if it exceeds 100 parts by weight, the rubber hardness increases and the elastic properties are lost, or the mechanical strength is extremely low. It cannot be put to practical use.
[0065]
The blending weight ratio of the cured resin of the thermosetting resin used in the present invention or the thermoplastic resin powder having a glass transition point of 300 ° C. or higher is 5 to 80 parts by weight with respect to 100 parts by weight of NBR. The reason is that if the blending ratio is less than 5 parts by weight, sufficient wear resistance cannot be imparted to NBR, and if blended in a large amount exceeding 80 parts by weight, the rubber hardness is increased and the elastic properties are lost, or the mechanical strength is reduced. Is extremely lowered and cannot be put to practical use. From such a tendency, a more preferable blending weight ratio of the cured powder of the thermosetting resin or the thermoplastic resin powder having a glass transition point of 300 ° C. or higher is 5 to 30 parts by weight with respect to 100 parts by weight of NBR. Moreover, the compounding weight ratio of spherical graphite is 5 to 80 parts by weight with respect to 100 parts by weight of NBR for the same reason as described above.
[0066]
Of course, a well-known compounding agent for rubber or a well-known additive may be compounded in this invention.
[0067]
(1) Reinforcing agent: carbon black, silica, clay, calcium carbonate, magnesium hydroxide, aluminum hydroxide, aluminum oxide, talc, mica, kaolin, bentonite, shirasu, wollastonite, silicon carbide, glass powder, carbon powder, Boron fiber, aramid fiber, etc.
(2) Vulcanization aid: zinc white, fatty acid, etc.
(3) Vulcanization accelerators: guanidines, sulfurs, aldehyde-amines, zincs, etc.
(4) Plasticizer: dimethyl phthalate, dioctyl phthalate, etc.
(5) Aging spinning agent: amines, phenols, etc.
(6) In addition, antioxidants, UV absorbers, flame retardants, colorants, etc.
Furthermore, oil, wax, and greases may be added to improve mold release properties and non-adhesiveness of the surface during molding. The compounding amount is preferably such that it does not affect the mechanical strength of the rubber molded product, that is, 2 to 20 parts by weight, more preferably 5 to 10 parts by weight with respect to 100 parts by weight of NBR.
[0068]
In addition to PTFE, tetrafluoroethylene-ethylene copolymer (ETFE), tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA), tetrafluoroethylene-hexafluoropropylene copolymer other than PTFE (FEP) or the like may be added.
[0069]
The method for mixing the above-mentioned various raw materials is not particularly limited, and is usually a widely used method, for example, NBR as a main raw material, and other fillers are mixed individually and sequentially or in a roll mixer, propeller. What is necessary is just to mix with a mixer, a kneader mixer, and other mixers. At this time, it is desirable to provide a temperature controller in order to prevent heat generation due to friction. Moreover, when using a roll mixer, it is preferable to carry out thinning with a roll interval of 3 mm or less as finish mixing.
[0070]
【Example】
The raw materials used in the examples and comparative examples are collectively shown as follows. In addition, although the mixture ratio of each component is weight%, about the raw material shown to (3)-(7), it showed with the weight part with respect to the total weight 100 of the raw material shown to (1) and (2).
[0071]
(1) Vinylidene fluoride-fluoropropylene copolymer (Asahi Monte Co., Ltd .: Technoflon FOR420)
(2) Tetrafluoroethylene-ethylene copolymer [ETFE] (Asahi Glass Co., Ltd .: Aflon COP)
(3) Low molecular weight fluoropolymer [low molecular weight TFE] (Asahi Glass Co., Ltd .: Lubricant L169)
(4) Low molecular weight fluorine-containing polymer (fluoropolyether) [low molecular weight FEP] (Nihon Enmont Co., Ltd .: Fomblin Z-DISOC)
(5) Carbon (Vandelbilt: MT carbon)
(6) Sodium stearate (general industrial material)
(7) Magnesium oxide [MgO] (general reagent)
(8) Calcium hydroxide [Ca (OH) ₂ ] (General reagents)
(9) Phenol resin (Kanebo Co., Ltd .: Bell Pearl H300)
(10) Nitrile-butadiene copolymer [NBR] (general industrial material hardness JIS-A70)
(11) Chloroprene-based copolymer [chloroprene rubber] (general industrial material hardness JIS-A70)
[Examples 1 to 4, Comparative Examples 1 to 5]
A fluorocarbon rubber (1) is wound around a roll mixer adjusted to a roll interval of 5 to 10 mm, and MT carbon, sodium stearate, MgO, Ca (OH) are sequentially added at the ratios shown in Table 1. ₂ And kneaded. Thereafter, the roll interval was adjusted to 1 mm, and mastication was performed about 10 times. In order to prevent frictional heat at this time, cooling water was always passed through the roll to keep the roll temperature at 60 ° C. or lower. Next, the cooling water is stopped, and the rubber temperature is adjusted to 70 ° C. or higher and 90 ° C. or lower by passing steam into the roll. Thereafter, the roll interval is returned to about 5 to 10 mm, and a small amount of low molecular weight fluoropolymer is added. It knead | mixed in the compounding ratio shown in Table 1, adding each one. Thereafter, the roll interval was narrowed again to 1 mm, and mastication was performed about 10 times.
[0072]
The 150 × 150 × t1 (mm) sheet in the compound obtained by the above steps was subjected to primary vulcanization (170 ° C., 10 minutes, press pressure 7 kgf / cm). ² ) And secondary vulcanization (230 ° C., 16 hours, free). For each test piece thus vulcanized, the friction / wear characteristics, non-adhesiveness, general characteristics, and actual machine durability were determined. Each test method is as follows.
[0073]
(A) Friction / wear test:
A ring-shaped sheet test piece having an inner diameter of φ17 mm and an outer diameter of φ21 mm was bonded to an aluminum alloy ring of φ17 × φ21 × t10 (mm) to obtain a friction test piece. The mating material was a polished product of bearing steel (SUJ2) and was evaluated with a thrust type friction tester. The test conditions were a peripheral speed of 128 m / min and a surface pressure of 3.5 kgf / cm. ² Friction coefficient and wear coefficient (× 10 ^-10 cm ³ / Kgf · m) is shown in the table.
[0074]
(B) Non-adhesion test:
The contact angle of each test piece with respect to water was measured with a goniometer-type contact angle measuring device. The larger the contact angle, the better the non-adhesiveness, and the results are also shown in the table.
[0075]
(C) Mechanical properties:
Based on JIS-K6301, the tensile strength, elongation, and hardness (JIS-A) were investigated with respect to the obtained sheet-like test piece, and the result was written together in the table | surface.
[0076]
(D) Actual machine durability test:
A tester in which a V-ring shaped test piece having a shaft diameter (inner diameter) of φ32 mm, an outer diameter of φ48 mm, and a width of 10 mm is mounted in a state shown in FIG. The shaft 5 was continuously operated for 500 hours at a speed of 200 revolutions per minute. In this case, the housing 7 with which the lip 4 of the V-ring 1 is slidably contacted is formed of bearing steel (SUSJ2).
[0077]
As a result of the above test, the wear amount of the V ring 1 is evaluated in three stages: ◯, the wear amount is 0.001 g or less, the wear amount is over 0.001 g and less than 0.005 g is Δ mark, and the wear amount is 0.005 g or more in x mark. This is also shown in the table.
[0078]
[Table 1]

[0079]
[Table 2]

[0080]
As is apparent from the results in Table 2, the test piece of the comparative example composed of a composition containing only fluororubber or a composition obtained by adding ETFE or low molecular weight TFE to fluororubber has a high coefficient of friction and durability against sliding properties. There was no sex. Similar results were obtained with test pieces made of nitrile rubber and chloroprene rubber.
[0081]
On the other hand, it can be seen that the test pieces of Examples 1 to 4 that satisfy all the conditions have all of non-adhesiveness, low friction characteristics, and wear resistance and can withstand continuous use for 500 hours.
[0082]
Next, the basic composition of the synthetic rubber used in Examples 5 to 13 and Comparative Examples 6 to 11 is shown below.
[0083]
[NBR basic blend A] (high nitrile type, nitrile amount 36-42%)
Nippon Synthetic Rubber Co., Ltd .: JSR220S 100 parts by weight
Sodium stearate: General industrial material 1 〃
Carbon black: FEF 30 〃
Vulcanization accelerator 1: Ouchi Shinsei Chemical Co., Ltd .: TT 2 〃
Vulcanization accelerator 2: Ouchi Shinsei Chemical Co., Ltd .: M 2 〃
Vulcanization aid: Zinc oxide (active zinc white) 10 〃
Vulcanizing agent: sulfur 1 〃
[NBR basic blend B] (medium nitrile type, nitrile content 24-30%)
Nippon Synthetic Rubber Co., Ltd .: JSR240S 100 parts by weight
Sodium stearate: General industrial material 1 〃
Carbon black: FEF 30 〃
Vulcanization accelerator 1: Ouchi Shinsei Chemical Co., Ltd .: TT 2 〃
Vulcanization accelerator 2: Ouchi Shinsei Chemical Co., Ltd .: M 2 〃
Vulcanization aid: Zinc oxide (active zinc white) 10 〃
Vulcanizing agent: sulfur 1 〃
[lubricant]
(1) Graphite co-precipitated PTFE [PTFE-1]
It was obtained by co-precipitation with graphite having an average particle diameter of 6 μm at a weight ratio of 7: 3, coagulation and washing after completion of the polymerization by emulsion polymerization.
(2) Dry blend PTFE with graphite [PTFE-2]
PTFE (Lubricant L182J) manufactured by Asahi Glass Co., Ltd. is dry blended with graphite having an average particle size of 6 μm and a weight ratio of 7: 3 using a Henschel mixer.
(3) PTFE [PTFE-3]
Asahi Glass Co., Ltd .: PTFE Lubricant L182J
(4) ETFE (Asahi Glass Co., Ltd .: Aflon COP Z8820)
(5) Spheroidal graphite (manufactured by Kanebo Co., Ltd .: Bell Pearl C2000)
(6) Silicone oil (manufactured by Shin-Etsu Silicone: KF96-300).
[0084]
[Examples 5 to 13, Comparative Examples 6 to 10]
NBR (220S) is wound around a roll mixer adjusted to a roll interval of about 5 to 10 mm, and inorganic filler, anti-aging agent, carbon, sulfur, and vulcanization accelerator are sequentially mixed in the proportions shown in basic formulation A or B. Finally, PTFE and other fillers were kneaded at the ratio shown in Table 3 or Table 4.
[0085]
Thereafter, the roll interval was adjusted to 1 mm, and thinning was performed 10 times. In order to prevent frictional heat at this time, cooling water was always passed through the roll to keep the roll temperature at 60 ° C. or lower. Next, the cooling water was stopped, and the rubber temperature was adjusted to 70 ° C. or higher and 90 ° C. or lower by passing steam into the roll. After that, thinning was performed 10 times with a roll interval of 1 mm to obtain 10 kg of compounds. .
[0086]
The compound obtained as described above was press-molded with a mold having a length of 300 mm, a width of 300 mm, and a thickness of 1 mm, and primary vulcanization (160 ° C., 10 minutes, press pressure of 120 kgf / cm). ² ) And secondary vulcanization (150 ° C., 4 hours, free). For each of the sheet-like test pieces thus vulcanized, the friction / wear characteristics, non-adhesiveness, and mechanical characteristics were determined.
[0087]
Further, a V-ring as shown in FIG. 1 was formed as an actual seal test piece, and an actual machine test was performed. Each test method is the same as the test method (a) except that the peripheral speed is 1.0 m / min and the surface pressure is 3.0 kgf / cm. ² As described above (a) to (d), except that the measurement was changed at the beginning of the test, 50 hours later, and 100 hours later. These results are shown in Table 5 or Table 6.
[0088]
[Table 3]

[0089]
[Table 4]

[0090]
[Table 5]

[0091]
[Table 6]

[0092]
It should be noted that it may be appropriately selected so as to provide a seal molded body most suitable as a composition, a characteristic value, etc., not less than the upper limit value and not more than the lower limit value or exceeding the upper limit value and less than the lower limit value shown in the table. .
[0093]
[Comparative Example 11]
In the same manner as in Comparative Example 6, a compound of NBR basic blend B was prepared and a test piece was molded. A commercially available coating agent for rubber (manufactured by Nippon Atchison Co., Ltd .: Emuralon 345) was formed on this test piece by spray coating to form a film of about 15 μm. After coating, it was dried in an electric furnace at 80 ° C. for 1 hour and further baked to complete a test piece.
[0094]
The obtained test piece was evaluated in the same test as in Comparative Example 6, and the results are shown in Table 6.
[0095]
As is apparent from the results of Tables 5 and 6, Comparative Example 6 containing only a general NBR formulation had a high friction coefficient and a large amount of wear. Further, 7 and 8 obtained by adding PTFE to NBR had a friction coefficient slightly lower than that of the rubber base material, but the wear characteristics were not sufficient. Further, in Comparative Example 9 in which spherical graphite was blended, the wear resistance was improved, but the friction coefficient was as large as about 0.8, and the followability gradually deteriorated even in the actual machine test. In Comparative Example 10 in which silicone oil was blended, the mechanical strength was remarkably lowered and the wear characteristics were extremely poor. In any of the comparative examples, much wear was observed in the actual machine test, and toner leakage was confirmed.
[0096]
On the other hand, Examples 1 to 12, in which powdery PTFE with a carbon material projecting on the surface and spherical graphite were used in combination, had a small decrease in mechanical strength and were excellent in low friction coefficient and wear resistance. In the actual machine test, stable low friction and low wear characteristics were confirmed. In addition, since Example 13 was obtained by adding spherical graphite together with PTFE, it had low friction and low wear characteristics as compared with the comparative example, and was resistant to use as in other examples.
[0097]
【effect】
In the present invention, as described above, the V-ring is formed of a lubricating rubber composition in which a fluorine rubber, a thermoplastic fluororesin, and a low molecular weight fluoropolymer having a predetermined molecular weight are blended in a predetermined ratio. There is an advantage that it has all of adhesiveness, low friction characteristics and wear resistance, and can withstand continuous use for a long time.
[0098]
Also in the invention in which the V-ring is a V-ring formed of a lubricating rubber composition containing acrylonitrile butadiene rubber, tetrafluoroethylene resin powder and spherical graphite, the N-ring material has sufficient rubber characteristics inherently low, There is an advantage of having both frictional characteristics and wear resistance.
[0099]
Therefore, the V-ring of the present invention is a seal member that exhibits a sufficient sealing performance utilizing the rubber characteristics, and has a long life, stable low friction characteristics, and excellent wear resistance.
[Brief description of the drawings]
FIG. 1 is a front view showing a general shape of a V-ring.
FIG. 2 is a longitudinal sectional view for explaining the usage state of a V-ring.
FIG. 3 is a schematic view showing a tetrafluoroethylene resin in a rubber base material.
[Explanation of symbols]
1 V-ring
2 Ring body
3 Hinge part
4 Lips
5 axis
6 Rolling bearing
7 Housing

Claims (5)

A V-shaped V-ring having a conical lip connected to one end of a ring body, which is made of tetrafluoroethylene resin powder having acrylonitrile butadiene rubber as a base material and a carbon material protruding on the surface, and a thermosetting resin. A V-ring formed of a lubricating rubber composition containing a cured powder of or a thermoplastic resin powder having a glass transition point of 300 ° C. or higher. Thermoplastic resin powder curing powder or the glass transition point of 300 ° C. or more thermosetting resins, V ring according to claim 1, wherein the graphite material spherical. Tetrafluoroethylene resin powder carbon material is projected on the surface, V ring according to claim 1, wherein the carbon material on the surface obtained by co-precipitation of carbon material is a tetrafluoroethylene resin powder which projects after the emulsion polymerization completion. Tetrafluoroethylene resin powder carbon material is projected on the surface, V-ring according to claim 1, wherein the tetrafluoroethylene resin powder carbon material is projected tetrafluoroethylene resin and carbon material on the surface obtained by dry mixing. The blending weight ratio of the components is 10 to 100 parts by weight of tetrafluoroethylene resin powder with a carbon material protruding on the surface with respect to 100 parts by weight of acrylonitrile butadiene rubber, the cured powder of the thermosetting resin or the glass transition point is 300 ° C. or higher. V ring according to claim 1, wherein the thermoplastic resin powder 5-80 parts by weight.

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