JP3705211B2 - Carbonaceous powder molding material and carbonaceous molded product - Google Patents
Carbonaceous powder molding material and carbonaceous molded product Download PDFInfo
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Description
【０００１】
【発明の属する技術分野】
本発明は、炭素質粉末と熱硬化性樹脂を主成分とする炭素質粉末成形材料及びその製造法に関する。また、この成形材料を加圧成形した炭素質成形品に関する。この成形品は、炭素電極や燃料電池セル間の導電性隔離板などに適したものである。
【０００２】
【従来の技術】
従来、炭素質粉末と熱硬化性樹脂（主としてフェノール樹脂）からなる炭素質粉末成形材料、ならびにその成形品は、次のようなものがある。
（１）炭素質粉末と熱硬化性樹脂を加圧混練し、これを粉砕してなる成形材料、ならびにこれを加熱加圧成形又は射出成形した成形品。
（２）炭素質粉末とフェノール樹脂粉末を水中に分散して混合し、これを乾燥してなる成形材料、ならびにこれを加熱加圧成形した成形品。
（３）炭素質粉末と熱硬化性樹脂粉末又は熱可塑性樹脂粉末とを溶剤を用い湿式混合後乾燥した成形材料、あるいは、溶剤を用いず乾式混合した成形材料、ならびにこれらを加熱加圧成形又は射出成形した成形品。
（４）樹脂成分を含まないものとして、膨張黒鉛を主体とした炭素質粉末、ならびにこれをそのまま高圧で圧縮成形した成形品。
【０００３】
しかし、上記各成形材料を成形した炭素質成形品は、特性的に種々不十分な点がある。
（１）の成形材料は、炭素質粉末と熱硬化性樹脂の均一な混練を実施するために、樹脂を炭素質粉末と同程度の質量で用いて調製される。このような成形材料を成形した成形品は、電気抵抗が大きくなる。
（２）の成形材料は、水分除去のために加熱乾燥の工程を経て調製されるが、加熱乾燥によって樹脂の硬化反応も同時に進行する。硬化反応が進み過ぎないように加熱乾燥を控え目にするので、水分が過剰に残留した成形材料とならざるを得ない。このような成形材料を成形した成形品は、強度が不十分となる。
（３）の成形材料は、溶剤除去のために加熱乾燥の工程を経て調製されるが、上記（２）と同様の理由で加熱乾燥を控え目にするので、溶剤が過剰に残留した成形材料とならざるを得ない。このような成形材料を成形した成形品は、強度が不十分となる。乾式混合による成形材料は、溶剤残留の問題はないが、機械的強度を確保するために樹脂含有量を増やす必要がある。このような成形材料を成形した成形品は、電気抵抗が大きくなる。
（４）の炭素質粉末は冷間で容易に成形できるが、成形品の強度確保が難しい。
【０００４】
【発明が解決しようとする課題】
上述のように、従来の炭素質粉末成形材料は、これを成形した成形品の電気抵抗を小さくし機械的強度も確保することが不十分であった。また、電気抵抗を小さくするべく樹脂含有量を極力制限するので、成形性が良いとはいえなかった。
本発明は上記問題に鑑み、電気抵抗が小さく機械的強度が大きい炭素質成形品の製造に寄与する炭素質粉末成形材料を提供することを課題とする。また、電気抵抗が小さく機械的強度が大きい炭素質成形品を提供することを課題とする。
【０００５】
【課題を解決するための手段】
上記の課題を解決するために、本発明に係る炭素質粉末成形材料は、炭素質粉末と熱硬化性樹脂を混合してなるものにおいて、主たる熱硬化性樹脂がベンゾオキサジン樹脂とジメチレンエーテル型フェノール樹脂又はレゾール型フェノール樹脂とであることを特徴とする。炭素質粉末と熱硬化性樹脂の混合比率は、９２／８〜７０／３０（質量比）とする。ベンゾオキサジン樹脂は、（ 6,6-(1-Methylethylidene)bis(3,4-dihydro-3-phenyl-2H-1,3-benzoxazine) と 6,6-(1-Methylethylidene)bis(3,4-dihydro-3-methyl-2H-1,3-benzoxazine) から選ばれる。
【０００６】
従来、炭素質粉末とフェノール樹脂を主成分とした炭素質粉末成形材料において、成形した成形品の電気抵抗を低くするために、樹脂の含有量を少なくすることが試みられた。しかし、樹脂の含有量を少なくすると、成形に際して、炭素質粉末粒子間の隙間を樹脂で十分埋めることができないので、成形品の機械的強度が低下する。そこで、一般的には、炭素質粉末とフェノール樹脂を質量比率７０／３０〜５０／５０の範囲で配合して、電気抵抗と機械的強度の一方の特性が極端に悪くならないように配慮している。従って、電気抵抗と機械的強度のいずれかの特性が不十分な状況にある。
本発明に係る炭素質粉末成形材料は、主たる熱硬化性樹脂として選択したベンゾオキサジン樹脂が成形時に著しく低粘度になり、また、硬化時にガスを発生しない。従って、炭素質粉末粒子間の隙間が流動性のよい樹脂で十分に埋まり、成形品に良好な機械的強度を付与することができる。同時に、樹脂は薄膜となるので、炭素質粉末粒子同士を接近させ電気抵抗を低くできるものと推測される。成形時の樹脂の流動性がよくガスの発生のないことことから、成形性も良好である。ガスの発生を少なくすることは、成形品にボイドやカスレができる原因を取除くことにもなる。炭素質粉末と熱硬化性樹脂の混合比率を９２／８〜７０／３０（質量比）とすることにより、成形した成形品の機械的強度と低電気抵抗の特性バランスが良好になる。
【０００７】
上記のベンゾオキサジン樹脂にジメチレンエーテル型フェノール樹脂を併用した炭素質粉末成形材料は、ベンゾオキサジン樹脂を主たる熱硬化性樹脂とする炭素質粉末成形材料と同様に、機械的強度が十分で低電気抵抗の成形品を良好に成形することに寄与するが、加えて、ジメチレンエーテル型フェノール樹脂は、溶融時の粘度が比較的低く、成形時の発生ガスも少ない上に硬化性に優れるため、一緒に用いるベンゾオキサジン樹脂の特徴を保持したまま硬化性を向上させることができる点で有利である。
【０００８】
上記のベンゾオキサジン樹脂にレゾール型フェノール樹脂を併用した炭素質粉末成形材料は、ベンゾオキサジン樹脂を主たる熱硬化性樹脂とする炭素質粉末成形材料と同様に、機械的強度が十分で低電気抵抗の成形品を良好に成形することに寄与するが、加えてレゾール型フェノール樹脂は、硬化性に優れるため、一緒に用いるベンゾオキサジン樹脂の硬化性を向上させることができる点で有利である。
【０００９】
上記各成形材料は、成形品の電気抵抗を低くするために、炭素質粉末として、好ましくは、膨張黒鉛粉末、鱗片状黒鉛粉末、人造黒鉛粉末から選ばれる少なくとも一つを含む。
【００１０】
本発明に係る炭素質粉末成形材料は、炭素質粉末と熱硬化性樹脂粉末の混合比率を、９２／８〜７０／３０（質量比）として実質的に乾式混合することにより製造するができ、熱硬化性樹脂粉末として、主として、ベンゾオキサジン樹脂粉末とジメチレンエーテル型フェノール樹脂粉末を混合して、又はベンゾオキサジン樹脂粉末とレゾール型フェノール樹脂粉末を混合して用いる。
【００１１】
本発明に係る炭素質成形品は、上記の炭素質粉末成形材料を加圧成形したものである。
【００１２】
【発明の実施の形態】
本発明において、主たる熱硬化性樹脂であるベンゾオキサジン樹脂は、6,6-(1-Methylethylidene)bis(3,4-dihydro-3-phenyl-2H-1,3-benzoxazine)、6,6-(1-Methylethylidene)bis(3,4-dihydro-3-methyl-2H-1,3-benzoxazine)など、市販品を単独又は混合して用いることができる。必要に応じて、安息香酸、マレイン酸などの硬化促進剤を加える。フェノール樹脂、エポキシ樹脂などを従たる熱硬化性樹脂として併用してもよい。
【００１３】
主たる熱硬化性樹脂として、ベンゾオキサジン樹脂と共にジメチレンエーテル型フェノール樹脂を用い用いる。また、ベンゾオキサジン樹脂と共にレゾール型フェノール樹脂を用いる。ジメチレンエーテル型フェノール樹脂ならびにレゾール型フェノール樹脂は、どちらも、例えば、フェノール類とホルマリン類を主成分としてアルカリ触媒下で反応させてメチロール化物とした後、加熱縮合脱水することにより得られる固形の自硬化性フェノール樹脂である。
【００１４】
また、本発明において、炭素質粉末は、鱗片状黒鉛粉末、膨張黒鉛粉末、人造黒鉛粉末から選ばれる少なくとも一つを含むことが望ましいが、そのほかに炭素繊維粉末を混合して用いてもよい。
鱗片状黒鉛粉末及び人造黒鉛粉末は市販品を利用でき、その粒径は５〜１００μｍの範囲が好ましい。膨張黒鉛粉末は公知の方法で製造することができる。例えば、鱗片状黒鉛を硫酸と硝酸との混液に浸漬処理して酸化合物とし、水洗した後、９００℃以上の温度で急速加熱し膨張黒鉛とする。その後、圧縮し粉砕することで目的の膨張黒鉛粉末を得ることができる。
【００１５】
炭素質粉末と熱硬化性樹脂（主たる樹脂は、ベンゾオキサジン樹脂とジメチレンエーテル型フェノール樹脂、又はベンゾオキサジン樹脂とレゾール型フェノール樹脂）の配合比率は、樹脂分が少なくなると成形品の機械的強度が低下し、樹脂分が多くなると成形品の電気抵抗が増大するので、質量比で、９２／８〜７０／３０とする。
【００１６】
成形材料の調製は、炭素質粉末と、ベンゾオキサジン樹脂粉末、又はベンゾオキサジン樹脂粉末とジメチレンエーテル型フェノール樹脂粉末、又はベンゾオキサジン樹脂粉末とレゾール型フェノール樹脂粉末に、必要に応じて、硬化促進剤、離形剤、表面改質剤、従たる他の熱硬化性樹脂などを添加し、これらを、シェイカー、ミキサー、タンブラー、ボールミル、雷潰機などを用いて直接乾式混合することにより行なう。前記乾式混合においては、混合後に乾燥を要しない程度の量であるなら溶剤を添加しても差し支えない。このような場合も、乾式混合という。ベンゾオキサジン樹脂、ジメチレンエーテル型フェノール樹脂ならびにレゾール型フェノール樹脂の粉末は、その粒径が小さいほど良く、７５μｍ以下が好ましい。
【００１７】
上述の炭素質粉末成形材料の成形は、通常の圧縮成形、射出成形などにより行なう。金型温度は、室温から３００℃の間に設定する。成形時に加熱加圧成形してもよいし、成形は加圧だけで行ない、その後成形品を金型から取り出し、樹脂を加熱硬化させてもよい。後者の場合、成形サイクルを短くすることができるので都合がよい。
【００１８】
【実施例】
参考例１〜５、比較例１〜２
鱗片状黒鉛粉末（平均粒径１５μｍ）又は膨張黒鉛粉末（平均粒径３０μｍ）と市販のベンゾオキサジン樹脂粉末（6,6-(1-Methylethylidene)bis(3,4-dihydro-3-phenyl-2H-1,3-benzoxazine)，室温で粉末（平均粒径４０μｍ），１４０℃における粘度０．６Ｎ・ｓ／ｍ２）及び安息香酸を、表１に示す配合でヘンシェルミキサーに投入し、５分間、乾式混合し炭素質粉末成形材料を得た。この成形材料を金型に投入し、温度１８０℃、圧力８０MPaで１０分間加熱加圧成形した。成形品を金型から取り出し、２００℃で１時間熱処理し炭素質粉末成形品を得た。
【００１９】
参考例６
鱗片状黒鉛粉末（平均粒径１５μｍ）と市販のベンゾオキサジン樹脂粉末（6,6-(1-Methylethylidene)bis(3,4-dihydro-3-phenyl-2H-1,3-benzoxazine)，室温で粉末，１４０℃における粘度０．６Ｎ・ｓ／ｍ２）及び安息香酸を、表１に示す配合でヘンシェルミキサーに投入し、５分間、乾式混合し炭素質粉末成形材料を得た。この成形材料を金型に投入し、温度１００℃、圧力８０MPaで０．５分間加熱加圧成形した後、成形品を金型から取り出し、室温から２５０℃まで５時間かけてゆっくり昇温し、加熱処理して炭素質粉末成形品を得た。
この参考例は、成形時には樹脂が完全には硬化しておらず、成形品を金型から取り出した後の加熱処理により樹脂の硬化を確実にしている。従って成形時間は短くなっている。
【００２０】
比較例３〜５
鱗片状黒鉛粉末（平均粒径１５μｍ）とレゾール型フェノール樹脂粉末（プレートフロー３４mm，平均粒径３０μｍ）を、表１に示す配合で実施例と同様に乾式混合し炭素質粉末成形材料を得た。この成形材料を用い、参考例１と同様に加熱加圧成形し、炭素質粉末成形品を得た。
【００２１】
従来例
鱗片状黒鉛粉末（平均粒径１５μｍ）と必要に応じメタノールで希釈した液状レゾール型フェノール樹脂（固形分３５質量％）を、表１に示す配合でヘンシェルミキサーに投入し、５分間混合した。混合後に、８０℃で約３時間乾燥して溶剤を取り除き、炭素質粉末成形材料を得た。この成形材料を金型に投入し、温度１８０℃、圧力８０MPaで１０分間加熱加圧成形し炭素質粉末成形品を得た。
【００２２】
上記各例の成形品（いずれも、１２５×１０×４mmの寸法形状）の曲げ強さ、電気抵抗を、ＪＩＳ−Ｋ−６９１１、ＪＩＳ−Ｃ−２５２５に準拠して測定した。また、成形品外観（成形性の指標）、硬化性、成形時のガス発生を評価した。硬化性は、成形品のバリをエア吹き付けで容易に除去できるかどうかで判断した。硬化性が不十分であると、粘着性があってバリを除去しにくくなる。その結果を表１に併せて示す。
【００２３】
【表１】
比較例３の特性は、本発明に係る参考例と遜色ないように見えるが、比較例３を樹脂配合質量比が同じである参考例２と対照すると、参考例２は曲げ強さにおいても電気抵抗においても比較例２より優れていることが判る。
【００２５】
実施例１〜５、比較例６〜７
鱗片状黒鉛粉末（平均粒径１５μｍ）又は膨張黒鉛粉末（平均粒径３０μｍ）と市販のベンゾオキサジン樹脂粉末（6,6-(1-Methylethylidene)bis(3,4-dihydro-3-phenyl-2H-1,3-benzoxazine)，室温で粉末（平均粒径４０μｍ），１４０℃における粘度０．６Ｎ・ｓ／ｍ２）と市販の固形ジメチレンエーテル型フェノール樹脂粉末（プレートフロー４５mm，平均粒径４０μｍ）を、表２に示す配合でヘンシェルミキサーに投入し、５分間、乾式混合し炭素質粉末成形材料を得た。この成形材料を金型に投入し、温度１８０℃、圧力８０MPaで１０分間加熱加圧成形した。成形品を金型から取り出し、２００℃で１時間熱処理し炭素質粉末成形品を得た。
【００２６】
実施例６〜８
鱗片状黒鉛粉末（平均粒径１５μｍ）と市販のベンゾオキサジン樹脂粉末（6,6-(1-Methylethylidene)bis(3,4-dihydro-3-phenyl-2H-1,3-benzoxazine)，室温で粉末（平均粒径４０μｍ），１４０℃における粘度０．６Ｎ・ｓ／ｍ２）と市販のレゾール型フェノール樹脂粉末（プレートフロー３４mm，平均粒径３０μｍ）を、表２に示す配合でヘンシェルミキサーに投入し、５分間、乾式混合し炭素質粉末成形材料を得た。この成形材料を金型に投入し、温度１８０℃、圧力８０MPaで１０分間加熱加圧成形した。成形品を金型から取り出し、２００℃で１時間熱処理し炭素質粉末成形品を得た。
【００２７】
上記各例の成形品（いずれも、１２５×１０×４mmの寸法形状）の曲げ強さ、電気抵抗を、ＪＩＳ−Ｋ−６９１１、ＪＩＳ−Ｃ−２５２５に準拠して測定した。また、成形品外観（成形性の指標）、硬化性、成形時のガス発生を評価した。その結果を表２に併せて示す。
【００２８】
【表２】
表２から、ベンゾオキサジン樹脂とジメチレンエーテル型フェノール樹脂を混合して用いることにより、成形品外観に加えて、硬化性も向上することが理解できる。ベンゾオキサジン樹脂とレゾール型フェノール樹脂を混合して用いることによっても、成形品外観と硬化性が向上するが、成形時のガス発生の点を考慮するとベンゾオキサジン樹脂とジメチレンエーテル型フェノール樹脂を混合して用いることが好ましい。
【００３０】
【発明の効果】
上述のように、本発明に係る炭素質粉末成形材料は、成形性が良好で、かつ、大きな機械的強度と低い電気抵抗を有した炭素質成形品の提供に寄与する。
主たる熱硬化性樹脂としてベンゾオキサジン樹脂とジメチレンエーテル型フェノール樹脂又はレゾール型フェノール樹脂を一緒に用いることにより、ベンゾオキサジン樹脂を主たる熱硬化性樹脂とする場合に比べて、樹脂の硬化性も良好となる。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a carbonaceous powder molding material mainly composed of carbonaceous powder and a thermosetting resin, and a method for producing the same. The present invention also relates to a carbonaceous molded product obtained by pressure molding this molding material. This molded product is suitable for a conductive separator between carbon electrodes and fuel cells.
[0002]
[Prior art]
Conventionally, carbonaceous powder molding materials composed of carbonaceous powder and a thermosetting resin (mainly phenol resin), and molded articles thereof are as follows.
(1) A molding material obtained by pressure-kneading carbonaceous powder and a thermosetting resin and pulverizing the same, and a molded product obtained by heat-pressing or injection molding the molding material.
(2) A molding material obtained by dispersing and mixing a carbonaceous powder and a phenol resin powder in water and drying the mixture, and a molded article obtained by heating and molding the molding material.
(3) Molding material obtained by wet-mixing carbonaceous powder and thermosetting resin powder or thermoplastic resin powder after using a solvent, or molding material obtained by dry-mixing without using a solvent, Injection molded products.
(4) A carbonaceous powder mainly composed of expanded graphite and a molded product obtained by compression-molding the powder as it is at a high pressure as containing no resin component.
[0003]
However, the carbonaceous molded products obtained by molding the above molding materials have various insufficient characteristics.
The molding material (1) is prepared using the resin in a mass comparable to that of the carbonaceous powder in order to perform uniform kneading of the carbonaceous powder and the thermosetting resin. A molded product obtained by molding such a molding material has a large electric resistance.
The molding material (2) is prepared through a heat drying process for removing moisture, and the resin curing reaction also proceeds simultaneously by heat drying. Heat drying is conservative so that the curing reaction does not proceed excessively, so the molding material has to be left with excessive moisture. A molded product obtained by molding such a molding material has insufficient strength.
The molding material of (3) is prepared through a heat drying process for removing the solvent. However, since heating drying is conservative for the same reason as the above (2), the molding material in which the solvent remains excessively is used. I have to be. A molded product obtained by molding such a molding material has insufficient strength. The molding material by dry mixing does not have a problem of residual solvent, but it is necessary to increase the resin content in order to ensure mechanical strength. A molded product obtained by molding such a molding material has a large electric resistance.
The carbonaceous powder (4) can be easily molded in the cold, but it is difficult to ensure the strength of the molded product.
[0004]
[Problems to be solved by the invention]
As described above, the conventional carbonaceous powder molding material is insufficient to reduce the electrical resistance and ensure the mechanical strength of a molded product obtained by molding the carbonaceous powder molding material. Further, since the resin content is limited as much as possible to reduce the electric resistance, it cannot be said that the moldability is good.
In view of the above problems, an object of the present invention is to provide a carbonaceous powder molding material that contributes to the production of a carbonaceous molded article having low electrical resistance and high mechanical strength. Another object of the present invention is to provide a carbonaceous molded article having a low electrical resistance and a high mechanical strength.
[0005]
[Means for Solving the Problems]
In order to solve the above problems, the carbonaceous powder molding material according to the present invention is a mixture of carbonaceous powder and a thermosetting resin, and the main thermosetting resin is a benzoxazine resin and a dimethylene ether type. It is a phenol resin or a resol type phenol resin . The mixing ratio of the carbonaceous powder and the thermosetting resin is 92/8 to 70/30 (mass ratio). Benzoxazine resins are ( 6,6- (1-Methylethylidene) bis (3,4-dihydro-3-phenyl-2H-1,3-benzoxazine) and 6,6- (1-Methylethylidene) bis (3,4 -dihydro-3-methyl-2H-1,3-benzoxazine) .
[0006]
Conventionally, attempts have been made to reduce the resin content in a carbonaceous powder molding material mainly composed of carbonaceous powder and a phenol resin in order to reduce the electric resistance of the molded product. However, if the resin content is reduced, the gap between the carbonaceous powder particles cannot be sufficiently filled with the resin during molding, so that the mechanical strength of the molded product is lowered. Therefore, in general, carbonaceous powder and phenol resin are blended in a mass ratio range of 70/30 to 50/50 so that one of the characteristics of electrical resistance and mechanical strength is not extremely deteriorated. Yes. Therefore, either the electric resistance or the mechanical strength is insufficient.
In the carbonaceous powder molding material according to the present invention, the benzoxazine resin selected as the main thermosetting resin has a remarkably low viscosity during molding and does not generate gas during curing. Accordingly, the gaps between the carbonaceous powder particles are sufficiently filled with the resin having good fluidity, and good mechanical strength can be imparted to the molded product. At the same time, since the resin becomes a thin film, it is presumed that the electric resistance can be lowered by bringing the carbonaceous powder particles closer to each other. Since the resin has good fluidity during molding and no gas is generated, the moldability is also good. Reducing the generation of gas also removes the cause of voids and creases in the molded product. By setting the mixing ratio of the carbonaceous powder and the thermosetting resin to 92/8 to 70/30 (mass ratio), the balance between the mechanical strength and the low electrical resistance characteristic of the molded product is improved.
[0007]
The carbonaceous powder molding material that uses the above-mentioned benzoxazine resin in combination with dimethylene ether type phenolic resin, like the carbonaceous powder molding material that uses benzoxazine resin as the main thermosetting resin, has sufficient mechanical strength and low electrical properties. Contributes to good molding of resistance molded products, but in addition, dimethylene ether type phenolic resin has a relatively low viscosity at the time of melting, less gas generated during molding, and excellent curability, This is advantageous in that the curability can be improved while maintaining the characteristics of the benzoxazine resin used together.
[0008]
The carbonaceous powder molding material in which a resol-type phenol resin is used in combination with the above-mentioned benzoxazine resin is similar to the carbonaceous powder molding material in which benzoxazine resin is the main thermosetting resin, and has sufficient mechanical strength and low electrical resistance. Although it contributes to good molding of the molded article, the resol-type phenol resin is advantageous in that it can improve the curability of the benzoxazine resin used together because it is excellent in curability.
[0009]
Each of the molding materials preferably contains at least one selected from expanded graphite powder, flaky graphite powder, and artificial graphite powder as the carbonaceous powder in order to reduce the electrical resistance of the molded product.
[0010]
The carbonaceous powder molding material according to the present invention can be produced by substantially dry-mixing the mixing ratio of the carbonaceous powder and the thermosetting resin powder as 92/8 to 70/30 (mass ratio), As thermosetting resin powder , benzoxazine resin powder and dimethylene ether type phenol resin powder are mainly mixed, or benzoxazine resin powder and resol type phenol resin powder are mixed and used .
[0011]
The carbonaceous molded product according to the present invention is obtained by pressure-molding the carbonaceous powder molding material.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
In the present invention, the main thermosetting resin benzoxazine resin is 6,6- (1-Methylethylidene) bis (3,4-dihydro-3-phenyl-2H-1,3-benzoxazine), 6,6- Commercially available products such as (1-Methylethylidene) bis (3,4-dihydro-3-methyl-2H-1,3-benzoxazine) can be used alone or in combination. If necessary, a hardening accelerator such as benzoic acid and maleic acid is added. You may use together as a thermosetting resin followed by a phenol resin, an epoxy resin, etc.
[0013]
And the main heat-hardening resin is used with a dimethylene ether type phenolic resin with benzoxazine resin. Also, Ru using resole phenolic resin with benzoxazine resin. Both the dimethylene ether type phenol resin and the resol type phenol resin are, for example, solid solids obtained by reacting in the presence of an alkali catalyst with phenols and formalins as the main components to form methylolated products, followed by heat condensation dehydration. It is a self-curing phenol resin.
[0014]
In the present invention, the carbonaceous powder preferably contains at least one selected from flaky graphite powder, expanded graphite powder, and artificial graphite powder, but in addition, carbon fiber powder may be mixed and used.
As the flaky graphite powder and artificial graphite powder, commercially available products can be used, and the particle diameter is preferably in the range of 5 to 100 μm. The expanded graphite powder can be produced by a known method. For example, scaly graphite is immersed in a mixed solution of sulfuric acid and nitric acid to form an acid compound, washed with water, and then rapidly heated to a temperature of 900 ° C. or higher to obtain expanded graphite. Then, the target expanded graphite powder can be obtained by compressing and pulverizing.
[0015]
The blending ratio of carbonaceous powder and thermosetting resin (the main resin is benzoxazine resin and dimethylene ether type phenol resin, or benzoxazine resin and resol type phenol resin) is the mechanical strength of the molded product when the resin content decreases. When the resin content is increased and the resin content is increased, the electrical resistance of the molded product is increased. Therefore, the mass ratio is set to 92/8 to 70/30.
[0016]
Molding materials can be prepared with carbonaceous powder and benzoxazine resin powder, or benzoxazine resin powder and dimethylene ether type phenol resin powder, or benzoxazine resin powder and resol type phenol resin powder, if necessary. An agent, a release agent, a surface modifier, and other related thermosetting resins are added, and these are directly dry mixed using a shaker, a mixer, a tumbler, a ball mill, a thunder crusher, or the like. In the dry mixing, a solvent may be added as long as the amount does not require drying after mixing. Such a case is also called dry mixing. The smaller the particle size of the benzoxazine resin, dimethylene ether type phenol resin, and resol type phenol resin powder, the better, 75 μm or less is preferable.
[0017]
The above-described carbonaceous powder molding material is molded by ordinary compression molding, injection molding, or the like. The mold temperature is set between room temperature and 300 ° C. Heat molding may be performed at the time of molding, or molding may be performed only by pressing, and then the molded product may be taken out from the mold and the resin may be cured by heating. In the latter case, it is convenient because the molding cycle can be shortened.
[0018]
【Example】
Reference Examples 1-5, Comparative Examples 1-2
Scaly graphite powder (average particle size 15 μm) or expanded graphite powder (average particle size 30 μm) and commercially available benzoxazine resin powder (6,6- (1-Methylethylidene) bis (3,4-dihydro-3-phenyl-2H -1,3-benzoxazine), powder at room temperature (average particle size 40 μm), viscosity at 140 ° C. 0.6 N · s / m 2 ) and benzoic acid are added to a Henschel mixer with the composition shown in Table 1 for 5 minutes. Then, dry mixing was performed to obtain a carbonaceous powder molding material. This molding material was put into a mold and heated and pressed at a temperature of 180 ° C. and a pressure of 80 MPa for 10 minutes. The molded product was removed from the mold and heat treated at 200 ° C. for 1 hour to obtain a carbonaceous powder molded product.
[0019]
Reference Example 6
Scaly graphite powder (average particle size 15 μm) and commercially available benzoxazine resin powder (6,6- (1-Methylethylidene) bis (3,4-dihydro-3-phenyl-2H-1,3-benzoxazine) at room temperature The powder, viscosity at 140 ° C., 0.6 N · s / m 2 ) and benzoic acid were added to a Henschel mixer with the formulation shown in Table 1, and dry mixed for 5 minutes to obtain a carbonaceous powder molding material. This molding material is put into a mold and heated and pressed at a temperature of 100 ° C. and a pressure of 80 MPa for 0.5 minutes, and then the molded product is taken out from the mold and slowly heated from room temperature to 250 ° C. over 5 hours. A heat treatment was performed to obtain a carbonaceous powder molded product.
In this reference example, the resin is not completely cured at the time of molding, and the curing of the resin is ensured by heat treatment after taking out the molded product from the mold. Therefore, the molding time is shortened.
[0020]
Comparative Examples 3-5
Scale-like graphite powder (average particle size 15 μm) and resol type phenolic resin powder (plate flow 34 mm, average particle size 30 μm) were dry-mixed in the same manner as in the examples with the formulation shown in Table 1 to obtain a carbonaceous powder molding material. . Using this molding material, heat and pressure molding was carried out in the same manner as in Reference Example 1 to obtain a carbonaceous powder molded product.
[0021]
Conventional Example Scalar graphite powder (average particle size 15 μm) and liquid resol type phenolic resin (solid content 35% by mass) diluted with methanol as necessary were charged into a Henschel mixer with the composition shown in Table 1 and mixed for 5 minutes. . After mixing, the solvent was removed by drying at 80 ° C. for about 3 hours to obtain a carbonaceous powder molding material. This molding material was put into a mold and subjected to heat and pressure molding at a temperature of 180 ° C. and a pressure of 80 MPa for 10 minutes to obtain a carbonaceous powder molded product.
[0022]
The bending strength and electric resistance of the molded products of the above examples (both sized and shaped of 125 × 10 × 4 mm) were measured according to JIS-K-6911 and JIS-C-2525. In addition, the appearance of molded products (index of moldability), curability, and gas generation during molding were evaluated. Curability was judged by whether or not burrs on the molded product could be easily removed by air blowing. If the curability is insufficient, it becomes sticky and it becomes difficult to remove burrs. The results are also shown in Table 1.
[0023]
[Table 1]
Although the characteristics of Comparative Example 3 seem to be inferior to those of the reference example according to the present invention, when Comparative Example 3 is contrasted with Reference Example 2 having the same resin blending mass ratio, Reference Example 2 is electrically in terms of bending strength. It can be seen that the resistance is superior to that of Comparative Example 2.
[0025]
Examples 1-5 , Comparative Examples 6-7
Scaly graphite powder (average particle size 15 μm) or expanded graphite powder (average particle size 30 μm) and commercially available benzoxazine resin powder (6,6- (1-Methylethylidene) bis (3,4-dihydro-3-phenyl-2H -1,3-benzoxazine), powder at room temperature (average particle size 40 μm), viscosity at 140 ° C. 0.6 N · s / m 2 ) and commercially available solid dimethylene ether type phenol resin powder (plate flow 45 mm, average particle size) 40 μm) was charged into a Henschel mixer with the formulation shown in Table 2, and dry mixed for 5 minutes to obtain a carbonaceous powder molding material. This molding material was put into a mold and heated and pressed at a temperature of 180 ° C. and a pressure of 80 MPa for 10 minutes. The molded product was removed from the mold and heat treated at 200 ° C. for 1 hour to obtain a carbonaceous powder molded product.
[0026]
Examples 6-8
Scaly graphite powder (average particle size 15 μm) and commercially available benzoxazine resin powder (6,6- (1-Methylethylidene) bis (3,4-dihydro-3-phenyl-2H-1,3-benzoxazine) at room temperature Powder (average particle size 40 μm), viscosity at 140 ° C. 0.6 N · s / m 2 ) and commercially available resol-type phenolic resin powder (plate flow 34 mm, average particle size 30 μm) in a Henschel mixer with the formulation shown in Table 2 The mixture was dry-mixed for 5 minutes to obtain a carbonaceous powder molding material. This molding material was put into a mold and heated and pressed at a temperature of 180 ° C. and a pressure of 80 MPa for 10 minutes. The molded product was removed from the mold and heat treated at 200 ° C. for 1 hour to obtain a carbonaceous powder molded product.
[0027]
The bending strength and electric resistance of the molded products of the above examples (both sized and shaped of 125 × 10 × 4 mm) were measured according to JIS-K-6911 and JIS-C-2525. In addition, the appearance of molded products (index of moldability), curability, and gas generation during molding were evaluated. The results are also shown in Table 2.
[0028]
[Table 2]
From Table 2, it can be understood that by using a mixture of benzoxazine resin and dimethylene ether type phenol resin, the curability is improved in addition to the appearance of the molded product. Mixing and using benzoxazine resin and resol type phenolic resin also improves the appearance and curability of the molded product, but considering the point of gas generation during molding, mixing benzoxazine resin and dimethylene ether type phenolic resin And preferably used.
[0030]
【The invention's effect】
As described above, the carbonaceous powder molding material according to the present invention contributes to the provision of a carbonaceous molded article having good moldability and having high mechanical strength and low electrical resistance.
The use of benzoxazine resin and dimethylene ether type phenol resin or resol-type phenolic resin together as the main thermoset resin, as compared with the case in which the benzoxazine resin mainly thermosetting resins, curable resins good It becomes.
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| US20200062911A1 (en) * | 2017-11-14 | 2020-02-27 | Takagi Chemicals, Inc. | Filler-Filled Highly Thermally Conductive Dispersion Composition Having Excellent Segregation Stability, Method for Producing Said Dispersion Composition, Filler-Filled Highly Thermally Conductive Material Using Said Dispersion Composition, Method for Producing Said Material, and Molded Article Obtained using Said Material |
| WO2022185601A1 (en) * | 2021-03-05 | 2022-09-09 | 住友ベークライト株式会社 | Thermosetting resin composition for sliding member, cured product formed from said composition and use of same |
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