JP3677336B2 - Fluororesin powder composition for sliding members - Google Patents
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Description
【０００１】
【発明の属する技術分野】
本発明は、潤滑油の存在下における摺動におい低摩擦性及び低摩耗性に優れ、更に軟質合金又は軟質金属からなる摺動相手材に損傷を与えない優れた成形品を成形可能な摺動部材用ふっ素樹脂粉末組成物に関する。
【０００２】
【従来の技術】
充填材含有ふっ素樹脂は摺動材やシール材等として広く使用されている。特に摺動材のような用途においては、低摩擦係数であると共に耐摩耗性に優れ、且つ耐熱性・耐薬品性に優れ、しかも摺動相手材を傷つけないといった多くの特性が要求される。ここで使用されるふっ素樹脂は圧縮成形用粉末であるポリテトラフルオロエチレン（以下ＰＴＦＥという）モールディングパウダーであり、一方充填材としてはガラス繊維、炭素繊維、グラファイト、二硫化モリブテン、ブロンズ粉末等の無機充填材、又は芳香族ポリエステル、ポリイミド、ポフェニレンサルファイド等の有機系充填材が知られている（特公昭４９−３６０８１号公報、特開昭５７−１０５４４２号公報、特開昭５８−１９３９７号公報等）。
【０００３】
【発明が解決しようとする課題】
しかしながら、従来の充填材含有ＰＴＦＥモールディングパウダーより成形される摺動材においては、ＰＴＦＥ自身が非粘着性の特性を有していることからＰＴＦＥと充填材とが密着性に乏しいため、充填材が摺動面においてＰＴＦＥから分離又は摺動面に露出し易く、摺接する相手材を傷つけたり摺動抵抗の増加を引き起こしたり、更には成形品の引っ張り強度、伸び、引っ張り弾性率等の機械的強度が不十分である等の問題点があった。更に近年、省エネルギー化、軽量化、及びメンテナンスフリー等の指向から摺動材が摺接する相手材の材質が軟質合金及び軟質金属、特にアルミニウム合金に変更されるものも多い。従来、摺動部材用の充填材含有ＰＴＦＥではＰＴＦＥ自身が摩耗しないような充填材を選択し使用してきたが、アルミニウムのような軟質で粘りのある材質に対してはＰＴＦＥ樹脂自身及び摺動相手材の摩耗が大きいという問題があった。本発明は、潤滑油の存在下における摺動において、低摩擦係数であると共に耐摩耗性に優れ、充填材が脱離し難く、且つ摺動相手材を傷つけない摺動部材用ふっ素樹脂粉末組成物を提供することを目的とする。
【０００４】
【課題を解決するための手段】
本発明に関わる摺動部材用ふっ素樹脂粉末組成物は、平均粒径１〜１００μｍのポリテトラフルオロエチレンモールディングパウダー及び平均粒径０．１〜０．５μｍの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）共重合体微粉末よりなるふっ素樹脂成分並びに充填剤として平均粒径５μｍ以下の無結晶アルミナ粉末及び平均粒径１０μｍ以下のコークス粉末を含み、両粉末の容量比（無結晶アルミナ粉末／コークス粉末）が０．５〜２．０の範囲で且つ両粉末の合計量がふっ素樹脂成分１００重量部に対し１０〜５０重量部の範囲のものである。
【０００５】
かかる粉末組成物を圧縮成形し次いで焼成することにより得られる成形品は、機械的強度が高く摺動に際しては摺動面での充填材の脱離が少なくなり、その結果として、成形品それ自身の摩耗及び摺動相手材の摩耗が少なく、摩擦係数も極めて小さいものとなる。
【０００６】
【発明の実施の形態】
本発明に用いられる無結晶アルミナ粉末は、平均粒径５μｍ以下、好ましくは０．５〜１μｍのものである。平均粒径が５μｍを越える場合には摺動面において成形品中のアルミナ粉末が脱離し易くなり、この脱離したアルミナ粉末は摺動相手材を傷つけるため好ましくない。無結晶アルミナ粉末とは、真比重が３．６５〜３．８５の範囲のＸ線回析的にはαアルミナへの転移が完了しない粉末であって、通常アルミナ粉末と呼ばれている真比重が３．９２のＸ線回析的にαアルミナへの転移が完了している粉末とは区別されるものである。無結晶性アルミナ粉末は、結晶アルミナ粉末を用いた場合に比べ、成形品の引っ張り弾性率を高く保つことが可能である。即ち、充分な剛性を保つことが出来ることに加え、摺動相手材の摩耗量も少ない。
【０００７】
本発明に用いられるコークス粉末は、平均粒径１０μｍ以下のものである。平均粒径が１０μｍを越える場合には、成形品の動摩擦係数が上がり摺動抵抗が大きくなるため好ましくない。
【０００８】
本発明における平均粒径５μｍ以下の無結晶アルミナ粉末と平均粒径１０μｍ以下のコークス粉末とは、その容積比で０．５〜２．０の範囲で使用される。上記範囲においては、ふっ素樹脂粉末の帯電のし易さ等にもかかわらず、アルミナ粉末に格別な表面処理を必要とせずに乾燥状態でふっ素樹脂粉末と均一に混合することが可能である。この範囲を外れてアルミナ粉末の量が多い場合には、摺動に際し成形品がひび割れを起こし易くなる傾向があり、アルミナ粉末の量が少ない場合には摺動相手材の摩耗量が増加する傾向がある。上記充填材のふっ素樹脂粉末への添加量は、樹脂１００重量部に対し１０〜５０重量部、好ましくは２０〜３０重量部の範囲である。添加量が１０重量部未満の場合には成形品の伸び値が大きく変形し易く、また成形品の充分な引っ張り弾性率、即ち充分な剛性を得ることが出来ない。添加量が５０重量部以上の場合には、成形品の伸び値が小さく脆くなり好ましくない。
【０００９】
上記充填材粉末に加え、平均粒径１０μｍ以下のグラファイト粉末を樹脂１００重量部に対し１〜１０重量の範囲で添加すれば、摺動時の発熱温度を低くすることが出来るため好ましい。
【００１０】
本発明で使用するふっ素樹脂成分としては、平均粒径１〜１００μｍのＰＴＦＥモールディングパウダーと平均粒径０．１〜０．５μｍの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（以下ＰＦＡという）微粉末の混合物を使用する。平均粒径０．１〜０．５μｍのＰＦＡ微粉末は焼成の際溶融し、充填材とＰＴＦＥモールディングパウダーの表面を充分に覆い、且つ充填材とＰＴＦＥモールディングパウダー間の空隙を確実に埋めて充填材とＰＴＦＥモールディングパウダーとの密着性を向上させ、成形品の機械的強度を向上させる。
【００１１】
本発明に用いられるＰＴＦＥモールディングパウダーは、懸濁重合によって得られるテトラフルオロエチレン（ＴＦＥ）の単独重合体（以下、無変性ＰＴＦＥという）単独であっても、１．０重量％以下のパーフルオロ（アルキルビニルエーテル）で変性したＴＦＥの重合体（以下、変性ＰＴＦＥという。）を粉砕した圧縮成形用粉末単独であっても、或は両者の混合物であっても良いが、無変性ＰＴＦＥと変性ＰＴＦＥの割合が重量比で６／４〜４／６の混合物の場合には、無変性ＰＴＦＥ単独の場合或は変性ＰＴＦＥを単独の場合に比べ、成形品の伸び、引っ張り強度、引っ張り弾性率等の機械的強度の向上、及び軟質合金または軟質金属からなる摺動相手材の摩耗量が少なくなるため特に好ましい。無変性ＰＴＦＥは、特に特公昭３４−１０１７７号に記載されているような多割合の繊維状粒子を含有している無変性ＰＴＦＥが、充填材との絡み合いが良く充填材の脱離を防止することができるため好ましく使用される。また、変性ＰＴＦＥは前記ＰＦＡと無変性ＰＴＦＥとの中間的な役割を持つものと考えられる。ＰＴＦＥモールディングパウダーの粒径は、無変性ＰＴＦＥ及び変性ＰＴＦＥ共に１〜１００μｍ、好ましくは１０〜５０μｍである。このように微粉化されたＰＴＦＥモールディングパウダーは、充填材及びＰＦＡ微粉末と均一に混合するに有利である。ＰＴＦＥモールディングパウダーの添加量はふっ素樹脂中７０〜９５重量％、好ましくは８５〜９５重量％である。添加量が７０重量％未満の場合には成形性が悪くなり、成形品の機械的特性も低下し、添加量が９５重量％を越えると耐摩耗性などの摺動特性の改善が顕著に認められなくなる。
【００１２】
本発明に用いられる平均粒径０．１〜０．５μｍのＰＦＡ微粉末は、テトラフルオロエチレンとパーフルオロアルキルビニルエーテルの乳化重合によって得られる平均粒径０．０５〜０．５μｍの共重合体微粒子を該微粒子の融点未満の温度で乾燥したものである。あるいは該微粒子を凝集したのち融点未満の温度で乾燥した平均粒径１〜１０００μｍの二次粒子の粉末であっても良い。なぜなら、融点未満の温度で乾燥された平均粒径１〜１０００μｍの二次粒子の粉末は、本発明の粉末組成物を撹拌する際容易に平均粒径０．１〜０．５μｍの微粉末に壊砕するからである。
【００１３】
ＰＦＡが微粉末である場合においてのみ本発明における効果、即ちＰＴＦＥモールディングパウダーと充填材との密着性の向上による機械的強度の向上及び摺動に際しての充填材の露出及び脱離防止による成形品それ自身の摩耗及び相手材の摩耗の著しい減少及び摩擦係数の著しい低下という効果を得ることが出来る。従って融点以上の温度で乾燥された場合には該微粒子又は該粒子は融着し、粉末組成物を撹拌する際においても平均粒径０．１〜０．５μｍの微粉末とならないため好ましくない。
【００１４】
本発明に用いられるＰＦＡのパーフルオロ（アルキルビニルエーテル）は、ＣＦ2 ＝ＣＦＯＲf （Ｒf は炭素数１〜１０のパーフルオロアルキル基を表わす）で示されるパーフルオロ（アルキルビニルエーテル）であり、特にパーフルオロ（エチルビニルエーテル）及びパーフルオロ（プロピルビニルエーテル）が好ましい。またＰＦＡは３７２℃における粘度が１×１０4 〜１×１０6 ボアズの範囲であり、テトラフルオロエチレン９７．５〜９５重量％とパーフルオロ（アルキルビニルエーテル）２．５〜５．０重量％からなる共重合体であることが好ましい。
【００１５】
本発明における平均粒径０．１〜０．５μｍのＰＦＡ微粉末の添加量は、ふっ素樹脂中５〜３０重量％、好ましくは５〜１５重量％である。添加量が１重量％未満の場合には、ＰＦＡ微粉末が焼成の際溶融しても充填材とＰＴＦＥモールディングパウダーの表面を充分に覆うことができず、また充填材とＰＴＦＥモールディングパウダー間の空隙を確実に埋めることも出来ない。添加量が３０重量％以上の場合には、効果の向上以上のコスト高による経済上の不利を招く他、焼成の際成形品の変形率が大きくなり好ましくない。
【００１６】
本発明の粉末組成物の混合に際しては、通常の公知の混合方法が採用される。例えば各成分をＶ型ブレンダー、タンブラー、ヘンシェルミキサー等の混合機で混合する。また本発明の粉末組成物の成形方法は、限定されるものではなく公知のＰＴＦＥ粉末の圧縮成形法を適用すれば良い。
【００１７】
以下、本発明を実施例及び比較例により具体的に説明するが、本発明は下記の実施例に限定されるものではない。原料としては下記のものを使用した。
ａ）平均粒径３５μｍのＰＴＦＥモールディングパウダー
（三井・デュポンフロロケミカル社製：テフロン(R) ７−Ｊ）
ｂ）平均粒径３５μｍの変性ＰＴＦＥモールディングパウダー
（三井・デュポンフロロケミカル社製：テフロン(R) ７０−Ｊ）
ｃ）平均粒径０．２μｍのＰＦＡ微粉末
（三井・デュポンフロロケミカル社製）
ｄ）平均粒径３０μｍのＰＦＡ粉末
（三井・デュポンフロロケミカル社製：ＭＰ−１０）
ｅ）無結晶アルミナ粉末
（日本軽金属社製：平均粒径０．７μｍ，真比重３．８）
ｆ）結晶アルミナ粉末
（日本軽金属社製：平均粒径０．６μｍ）
ｇ）コークス粉末
（日本カーボン社製：平均粒径７μｍ，真比重１．９９）
ｈ）グラファイト粉末
（エスイーシ社製：平均粒径１μｍ）
【００１８】
【実施例１〜３及び比較例１〜５】
上記原料を表１に示される割合にてヘンシェルミキサーで均一に混合して摺動部材用ふっ素樹脂粉末組成物を調製した。表１に示される充填材である無結晶アルミナ粉末、結晶アルミナ粉末、コークス粉末及びグラファイト粉末の量は、樹脂１００重量部に対する充填材の重量部（以下、ＰＰｈという）である。このふっ素樹脂粉末組成物について、伸び値、引っ張り強度、引っ張り弾性率、動摩擦係数、及び摩耗量を下記の方法により測定した。
【００１９】
【伸び値、引っ張り強度、引っ張り弾性率】
表１に示されるふっ素樹脂粉末組成物を１５００ｋｇ／ｃｍ2 で予備成形し、３８０℃で１時間焼成し、外径５０ｍｍ、厚さ２ｍｍの円盤を得た。これからＡＳＴＭ−１４５７に従いマイクロダンベルにて試験片を打ち抜き、伸び値、引っ張り強度、引っ張り弾性率を測定した。結果を表１に示す。
【００２０】
【動摩擦係数、摩耗量】
表１に示されるふっ素樹脂粉末組成物を１５００ｋｇ／ｃｍ2 で予備成形し、３８０℃で１時間焼成し、外径６５ｍｍ、内径４８ｍｍ、高さ３０ｍｍの円筒状成形物を得た。これから外径５２ｍｍ、内径４８ｍｍ、高さ２ｍｍのリングを切削加工し試験片とした。この試験片について次の摩擦摩耗試験方法により動摩擦係数及び摩耗量を測定した。ＲＩＫ式自動昇圧型高圧摩擦摩耗試験機を使用し、摺動相手材としてＡＬ合金ダイカスト（ＪＩＳ１９７６ ２１１８記載のＡＤＣ１２：表面粗さＲａ＝２〜３μｍ）を用いた。動摩擦係数は、温度８０℃のオートトランスミッション用オイルを流量１５０ｃｃ／分になるよう供給し、荷重２５ｋｇ／ｃｍ2 、速度１１ｍ／秒、時間５時間で摺動を行い測定した。摩耗量は摺動終了後のＡＬ合金ダイカストの摩耗量を測定した。結果を表１に示す。
【００２１】
実施例１〜３のふっ素樹脂粉末組成物を圧縮成形し次いで焼成することにより得られる成形品は、伸び値、引っ張り強度、引っ張り弾性率、動摩擦係数、及び摩耗量の点で優れている。
【００２２】
表１から明らかなように、無結晶アルミナ粉末が添加されていない比較例１の場合には、摺動相手材であるＡＬ合金ダイカストの摩耗量が大きいほか、成形品の引っ張り弾性率が低く剛性に欠けること及び変形しやすいことがわかる。
【００２３】
またコークス粉末が添加されない比較例２の場合には、伸び値が著しく小さくアルミナ粉末とＰＴＦＥモールディングパウダーとが均一に混合されなかったことがわかる。更に比較例２は成形品それ自身も摺動に際しひび割れを起こし、動摩擦係数は実施例１〜３に比して大きく軟質材を摺動相手材とすることは出来ないことがわかる。
【００２４】
【表１】
ＰＦＡ微粉末が添加されない比較例３の場合には、動摩擦係数が大きく発熱が起こり２時間で摺動を中止した。そのため、比較例３の測定値（＊印）はこの時点での値である。さらに比較例３の伸び値は実施例１〜３に比べその値が小さいことからＰＴＦＥモールディングパウダーと充填材とのなじみが悪いことがわかる。
【００２６】
更に、平均粒径０．２μｍのＰＦＡ微粉末ではない平均粒径３０μｍのＰＦＡ粉末が添加された比較例４の場合には、摺動相手材であるＡＬ合金ダイカストの摩耗量が実施例１〜３に比して非常に大きく軟質材を摺動相手材とすることは出来ないことがわかる。また比較例３よりも更に伸び値が小さいことからＰＴＦＥモールディングパウダーと充填材とのなじみが非常に悪いことがわかる。
【００２７】
また、無結晶アルミナ粉末に代えて結晶アルミナ粉末を使用した比較例５は動摩擦係数、摩耗量共に大きい。
【００２８】
【実施例４〜６】
ここで充填剤としてのグラファイト粉末の効果を説明する。前記原料を表２に示される割合にてヘンシェルミキサーで均一に混合して摺動部材用ふっ素樹脂粉末組成物を調製した。このふっ素樹脂粉末組成物について、実施例１〜３と同様なリング状の摩擦摩耗試験用試験片を作り、この試験片について摩擦摩耗試験を行った際の摺動相手材であるＡＬ合金ダイカストの摺動中における発熱温度を測定した結果を表２に示す。グラファイト粉末を含まない場合（実施例４）に比べて、グラファイト粉末を含む場合（実施例５、６）は発熱温度が低い。
【００２９】
【表２】
【発明の効果】
本発明の摺動部材用樹脂組成物は、アルミニウム合金などの軟質金属及び軟質合金を摺動相手材としても、自己の摩耗及び相手摺動部材の摩耗が共に少なく、特に高摺動特性が要求される過酷な使用条件、即ち、高温、高速、高荷重下での使用に際し優れた摺動特性を示すのみではなく、摺動部材用樹脂組成物として要求される耐熱性、耐薬品性、寸法安定性、優れた機械的特性をも具備する。[0001]
BACKGROUND OF THE INVENTION
The present invention is excellent in low friction and low wear in sliding in the presence of lubricating oil, and is capable of forming an excellent molded product that does not damage a sliding counterpart made of a soft alloy or a soft metal. The present invention relates to a fluororesin powder composition for members.
[0002]
[Prior art]
Filler-containing fluororesins are widely used as sliding materials and sealing materials. In particular, in applications such as sliding materials, many characteristics are required such as a low coefficient of friction, excellent wear resistance, excellent heat resistance and chemical resistance, and no damage to the sliding material. The fluororesin used here is polytetrafluoroethylene (hereinafter referred to as PTFE) molding powder which is a powder for compression molding, while the filler is inorganic such as glass fiber, carbon fiber, graphite, molybdenum disulfide, bronze powder, etc. Organic fillers such as fillers or aromatic polyesters, polyimides, and polyphenylene sulfides are known (Japanese Patent Publication Nos. 49-36081, 57-105442, 58-19397). etc).
[0003]
[Problems to be solved by the invention]
However, in the sliding material molded from the conventional filler-containing PTFE molding powder, since PTFE itself has non-adhesive properties, PTFE and the filler are poor in adhesion, so the filler The sliding surface is easily separated from PTFE or exposed to the sliding surface, damages the mating material in sliding contact, causes an increase in sliding resistance, and mechanical strength such as the tensile strength, elongation, and tensile modulus of the molded product. There were problems such as insufficient. Furthermore, in recent years, there are many cases where the material of the mating material with which the sliding material comes into sliding contact is changed to a soft alloy and a soft metal, particularly an aluminum alloy, in order to save energy, reduce weight, and maintain maintenance. Conventionally, in the PTFE containing filler for the sliding member, a filler that does not wear the PTFE itself has been selected and used. However, for a soft and sticky material such as aluminum, the PTFE resin itself and the sliding partner are used. There was a problem that material wear was large. The present invention relates to a fluororesin powder composition for a sliding member that has a low coefficient of friction, excellent wear resistance, is difficult to detach the filler, and does not damage the sliding counterpart during sliding in the presence of lubricating oil. The purpose is to provide.
[0004]
[Means for Solving the Problems]
The fluororesin powder composition for sliding members according to the present invention comprises polytetrafluoroethylene molding powder having an average particle size of 1 to 100 μm and tetrafluoroethylene / perfluoro (alkyl vinyl ether) having an average particle size of 0.1 to 0.5 μm. Fluorine resin component consisting of copolymer fine powder and amorphous alumina powder having an average particle diameter of 5 μm or less as a filler and coke powder having an average particle diameter of 10 μm or less as a filler, volume ratio of both powders (amorphous alumina powder / coke powder) Is in the range of 0.5 to 2.0, and the total amount of both powders is in the range of 10 to 50 parts by weight with respect to 100 parts by weight of the fluororesin component.
[0005]
A molded product obtained by compression molding and then firing such a powder composition has high mechanical strength and less detachment of the filler on the sliding surface during sliding. As a result, the molded product itself Wear and the sliding counterpart material are small, and the friction coefficient is extremely small.
[0006]
DETAILED DESCRIPTION OF THE INVENTION
The amorphous alumina powder used in the present invention has an average particle size of 5 μm or less, preferably 0.5 to 1 μm. When the average particle diameter exceeds 5 μm, the alumina powder in the molded product is easily detached on the sliding surface, and this detached alumina powder is not preferable because it damages the sliding partner material. Amorphous alumina powder is a powder whose true specific gravity is in the range of 3.65 to 3.85 and in which the transition to α-alumina is not completed by X-ray diffraction. Is distinguished from the powder having a transition to α-alumina of 3.92 by X-ray diffraction. The amorphous alumina powder can keep the tensile modulus of the molded product high as compared with the case where the crystalline alumina powder is used. That is, in addition to being able to maintain sufficient rigidity, the amount of wear of the sliding counterpart material is also small.
[0007]
The coke powder used in the present invention has an average particle size of 10 μm or less. When the average particle diameter exceeds 10 μm, the dynamic friction coefficient of the molded product increases and the sliding resistance increases, which is not preferable.
[0008]
The amorphous alumina powder having an average particle size of 5 μm or less and the coke powder having an average particle size of 10 μm or less in the present invention are used in a volume ratio of 0.5 to 2.0. Within the above range, the alumina powder can be uniformly mixed with the fluororesin powder in a dry state without requiring any special surface treatment despite the ease of charging of the fluororesin powder. When the amount of alumina powder is outside this range, the molded product tends to crack when sliding, and when the amount of alumina powder is small, the wear amount of the sliding material tends to increase. There is. The amount of the filler added to the fluororesin powder is in the range of 10 to 50 parts by weight, preferably 20 to 30 parts by weight with respect to 100 parts by weight of the resin. When the addition amount is less than 10 parts by weight, the elongation value of the molded product is greatly deformed easily, and sufficient tensile elastic modulus of the molded product, that is, sufficient rigidity cannot be obtained. When the amount added is 50 parts by weight or more, the elongation value of the molded product is small and fragile, which is not preferable.
[0009]
In addition to the filler powder, it is preferable to add a graphite powder having an average particle size of 10 μm or less in a range of 1 to 10 weights with respect to 100 parts by weight of the resin because the heat generation temperature during sliding can be lowered.
[0010]
As the fluororesin component used in the present invention, PTFE molding powder having an average particle diameter of 1 to 100 μm and tetrafluoroethylene / perfluoro (alkyl vinyl ether) copolymer (hereinafter referred to as PFA) having an average particle diameter of 0.1 to 0.5 μm. ) Use a mixture of fine powders. PFA fine powder with an average particle size of 0.1 to 0.5 μm melts during firing, sufficiently covers the surface of the filler and PTFE molding powder, and reliably fills the gap between the filler and PTFE molding powder The adhesion between the material and the PTFE molding powder is improved, and the mechanical strength of the molded product is improved.
[0011]
The PTFE molding powder used in the present invention may be a tetrafluoroethylene (TFE) homopolymer obtained by suspension polymerization (hereinafter referred to as non-modified PTFE) alone, which is 1.0% by weight or less perfluoro ( The powder for compression molding obtained by pulverizing a TFE polymer (hereinafter referred to as modified PTFE) modified with an alkyl vinyl ether may be used alone or as a mixture of both. In the case of a mixture having a ratio of 6/4 to 4/6 by weight, the machine of elongation, tensile strength, tensile modulus, etc. of the molded product is compared with the case of non-modified PTFE alone or modified PTFE alone. This is particularly preferable because of improving the mechanical strength and reducing the wear amount of the sliding counterpart made of a soft alloy or soft metal. Non-modified PTFE, particularly as described in Japanese Patent Publication No. 34-10177, contains unmodified PTFE containing a large proportion of fibrous particles and has good entanglement with the filler to prevent the detachment of the filler. Can be used preferably. Modified PTFE is considered to have an intermediate role between PFA and unmodified PTFE. The particle size of the PTFE molding powder is 1 to 100 μm, preferably 10 to 50 μm for both unmodified PTFE and modified PTFE. The finely powdered PTFE molding powder is advantageous for uniform mixing with the filler and PFA fine powder. The addition amount of PTFE molding powder is 70 to 95% by weight, preferably 85 to 95% by weight in the fluororesin. If the addition amount is less than 70% by weight, the moldability is deteriorated and the mechanical properties of the molded product are also deteriorated. If the addition amount exceeds 95% by weight, the improvement of the sliding characteristics such as wear resistance is recognized remarkably. It becomes impossible.
[0012]
The fine PFA powder having an average particle size of 0.1 to 0.5 μm used in the present invention is a copolymer fine particle having an average particle size of 0.05 to 0.5 μm obtained by emulsion polymerization of tetrafluoroethylene and perfluoroalkyl vinyl ether. Is dried at a temperature lower than the melting point of the fine particles. Alternatively, it may be a powder of secondary particles having an average particle diameter of 1 to 1000 μm, which is obtained by aggregating the fine particles and then drying at a temperature lower than the melting point. This is because the powder of secondary particles having an average particle diameter of 1-1000 μm dried at a temperature lower than the melting point is easily converted into a fine powder having an average particle diameter of 0.1-0.5 μm when the powder composition of the present invention is stirred. Because it breaks down.
[0013]
The effect in the present invention only when the PFA is a fine powder, that is, a molded product by improving the mechanical strength by improving the adhesion between the PTFE molding powder and the filler, and preventing the filler from being exposed and detached during sliding. It is possible to obtain the effects of a significant decrease in the wear of the own member and the counterpart material and a significant decrease in the friction coefficient. Accordingly, when dried at a temperature equal to or higher than the melting point, the fine particles or the particles are fused, and even when the powder composition is stirred, it is not preferable because it does not become a fine powder having an average particle size of 0.1 to 0.5 μm.
[0014]
The perfluoro (alkyl vinyl ether) of PFA used in the present invention is perfluoro (alkyl vinyl ether) represented by CF 2 ═CFOR f (R f represents a perfluoroalkyl group having 1 to 10 carbon atoms), Perfluoro (ethyl vinyl ether) and perfluoro (propyl vinyl ether) are preferred. PFA has a viscosity at 372 ° C. in the range of 1 × 10 4 to 1 × 10 6 boaz, from 97.5 to 95% by weight of tetrafluoroethylene and 2.5 to 5.0% by weight of perfluoro (alkyl vinyl ether). It is preferable that it is a copolymer.
[0015]
The amount of fine PFA powder having an average particle size of 0.1 to 0.5 μm in the present invention is 5 to 30% by weight, preferably 5 to 15% by weight in the fluororesin. When the added amount is less than 1% by weight, the surface of the filler and PTFE molding powder cannot be sufficiently covered even if the PFA fine powder melts during firing, and the gap between the filler and PTFE molding powder is not sufficient. Can not be filled reliably. When the addition amount is 30% by weight or more, it causes an economic disadvantage due to the cost increase beyond the improvement of the effect, and the deformation rate of the molded product is increased at the time of firing, which is not preferable.
[0016]
In mixing the powder composition of the present invention, an ordinary known mixing method is employed. For example, each component is mixed by a mixer such as a V-type blender, tumbler, Henschel mixer or the like. Moreover, the molding method of the powder composition of the present invention is not limited, and a known compression molding method of PTFE powder may be applied.
[0017]
EXAMPLES Hereinafter, although an Example and a comparative example demonstrate this invention concretely, this invention is not limited to the following Example. The following were used as raw materials.
a) PTFE molding powder with an average particle size of 35 μm (Mitsui / DuPont Fluorochemicals: Teflon (R) 7-J)
b) an average particle size of 35μm modified PTFE molding powder (Mitsui-Dupont Fluorochemicals Co., Ltd. Teflon (R) 70-J)
c) PFA fine powder with an average particle size of 0.2 μm (Mitsui / Dupont Fluoro Chemical Co., Ltd.)
d) PFA powder having an average particle size of 30 μm (Mitsui / DuPont Fluorochemical Co., Ltd .: MP-10)
e) Amorphous alumina powder (manufactured by Nippon Light Metal Co., Ltd .: average particle size 0.7 μm, true specific gravity 3.8)
f) Crystalline alumina powder (Nippon Light Metal Co., Ltd .: average particle size 0.6 μm)
g) Coke powder (Nippon Carbon Co., Ltd .: average particle size 7 μm, true specific gravity 1.99)
h) Graphite powder (manufactured by ESC: average particle size 1 μm)
[0018]
Examples 1 to 3 and Comparative Examples 1 to 5
The above raw materials were uniformly mixed at a ratio shown in Table 1 with a Henschel mixer to prepare a fluororesin powder composition for sliding members. The amounts of amorphous alumina powder, crystalline alumina powder, coke powder, and graphite powder, which are fillers shown in Table 1, are parts by weight of filler (hereinafter referred to as PPh) with respect to 100 parts by weight of resin. With respect to this fluororesin powder composition, the elongation value, tensile strength, tensile elastic modulus, dynamic friction coefficient, and wear amount were measured by the following methods.
[0019]
[Elongation value, tensile strength, tensile modulus]
The fluororesin powder composition shown in Table 1 was preformed at 1500 kg / cm 2 and fired at 380 ° C. for 1 hour to obtain a disk having an outer diameter of 50 mm and a thickness of 2 mm. From this, the test piece was punched out with a micro dumbbell according to ASTM-1457, and the elongation value, tensile strength, and tensile elastic modulus were measured. The results are shown in Table 1.
[0020]
[Dynamic friction coefficient, wear amount]
The fluororesin powder composition shown in Table 1 was preformed at 1500 kg / cm 2 and fired at 380 ° C. for 1 hour to obtain a cylindrical molded product having an outer diameter of 65 mm, an inner diameter of 48 mm, and a height of 30 mm. From this, a ring having an outer diameter of 52 mm, an inner diameter of 48 mm, and a height of 2 mm was cut into a test piece. The dynamic friction coefficient and the wear amount of this test piece were measured by the following friction and wear test method. A RIK type automatic pressurization type high-pressure frictional wear tester was used, and an AL alloy die casting (ADC12 described in JIS 1976 2118: surface roughness Ra = 2 to 3 μm) was used as a sliding partner material. The dynamic friction coefficient was measured by supplying oil for autotransmission at a temperature of 80 ° C. at a flow rate of 150 cc / min, sliding at a load of 25 kg / cm 2 , a speed of 11 m / sec, and a time of 5 hours. The amount of wear was determined by measuring the amount of wear of the AL alloy die cast after sliding. The results are shown in Table 1.
[0021]
Molded articles obtained by compression molding and then firing the fluororesin powder compositions of Examples 1 to 3 are excellent in terms of elongation value, tensile strength, tensile elastic modulus, dynamic friction coefficient, and wear amount.
[0022]
As is apparent from Table 1, in the case of Comparative Example 1 in which the amorphous alumina powder is not added, the wear amount of the AL alloy die casting as the sliding partner material is large, and the molded product has low tensile elastic modulus and rigidity. It can be seen that it is lacking and is easily deformed.
[0023]
Further, in the case of Comparative Example 2 in which no coke powder was added, it can be seen that the elongation value was remarkably small and the alumina powder and the PTFE molding powder were not uniformly mixed. Furthermore, in Comparative Example 2, the molded product itself cracks when sliding, and the dynamic friction coefficient is larger than that of Examples 1 to 3, and it can be seen that a soft material cannot be used as the sliding counterpart material.
[0024]
[Table 1]
In the case of Comparative Example 3 in which no PFA fine powder was added, the dynamic friction coefficient was large and heat generation occurred, and the sliding was stopped after 2 hours. Therefore, the measured value (* mark) of Comparative Example 3 is a value at this time. Furthermore, since the elongation value of Comparative Example 3 is smaller than those of Examples 1 to 3, it can be seen that the familiarity between PTFE molding powder and the filler is poor.
[0026]
Further, in the case of Comparative Example 4 in which PFA powder having an average particle size of 30 μm, which is not a PFA fine powder having an average particle size of 0.2 μm, was added, the wear amount of the AL alloy die casting as the sliding counterpart material was determined in Examples 1 to 3. It can be seen that a soft material cannot be used as a sliding counterpart material, which is much larger than 3. Further, since the elongation value is smaller than that of Comparative Example 3, it is understood that the familiarity between the PTFE molding powder and the filler is very bad.
[0027]
Further, Comparative Example 5 using the crystalline alumina powder instead of the amorphous alumina powder has a large coefficient of dynamic friction and wear.
[0028]
Examples 4 to 6
Here, the effect of the graphite powder as the filler will be described. The raw materials were uniformly mixed at a ratio shown in Table 2 with a Henschel mixer to prepare a fluororesin powder composition for sliding members. With respect to this fluororesin powder composition, a ring-shaped test piece for frictional wear test similar to that of Examples 1 to 3 was prepared, and the AL alloy die casting, which is a sliding counterpart when the frictional wear test was performed on this test piece, was made. Table 2 shows the results of measuring the heat generation temperature during sliding. When the graphite powder is included (Examples 5 and 6), the heat generation temperature is lower than when the graphite powder is not included (Example 4).
[0029]
[Table 2]
【The invention's effect】
The resin composition for a sliding member of the present invention has both low wear and wear of the mating sliding member even when a soft metal such as an aluminum alloy and a soft alloy are used as the sliding mating material, and particularly high sliding characteristics are required. In addition to exhibiting excellent sliding characteristics when used under severe usage conditions, i.e., high temperature, high speed, and high load, heat resistance, chemical resistance and dimensions required as a resin composition for sliding members It also has stability and excellent mechanical properties.
Claims (4)
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP33070495A JP3677336B2 (en) | 1995-12-19 | 1995-12-19 | Fluororesin powder composition for sliding members |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP33070495A JP3677336B2 (en) | 1995-12-19 | 1995-12-19 | Fluororesin powder composition for sliding members |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH09169880A JPH09169880A (en) | 1997-06-30 |
| JP3677336B2 true JP3677336B2 (en) | 2005-07-27 |
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| JP33070495A Expired - Fee Related JP3677336B2 (en) | 1995-12-19 | 1995-12-19 | Fluororesin powder composition for sliding members |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| JP4262341B2 (en) * | 1998-12-02 | 2009-05-13 | 株式会社竹中工務店 | Slip isolation device and isolation structure |
| JP5034150B2 (en) | 2000-12-05 | 2012-09-26 | 旭硝子株式会社 | Polytetrafluoroethylene granulated product and molded product thereof |
| JP2002209975A (en) * | 2001-01-19 | 2002-07-30 | Daikyo Seiko Ltd | Laminated rubber stopper for medical vial |
| US7892600B2 (en) * | 2002-12-06 | 2011-02-22 | E. I. Du Pont De Nemours And Company | Rotolining process |
| JP2004346265A (en) * | 2003-05-26 | 2004-12-09 | Hitachi Industrial Equipment Systems Co Ltd | Sliding material and oil-free scroll compressor |
| JP2006096991A (en) * | 2004-08-31 | 2006-04-13 | Kurabe Ind Co Ltd | Ptfe resin molded item, monolithic structure using ptfe resin molded body and their preparation process |
| JP4983153B2 (en) * | 2006-08-24 | 2012-07-25 | ダイキン工業株式会社 | Fluorine-containing resin aqueous dispersion |
| EP2767557B1 (en) * | 2013-02-14 | 2017-03-22 | 3M Innovative Properties Company | Fluoropolymer compositions with microspheres |
| KR20190101958A (en) * | 2016-10-17 | 2019-09-02 | 부르크하르트 콤프레션 아게 | Sealing member and / or guide ring made of a composition of polytetrafluoroethylene, perfluoroalkoxy polymer and filler |
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1995
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