JP3736479B2 - Semiconductive resin molded product - Google Patents

Description

【００９１】
本発明において用いられる上記一般式［Ｉ］で示されるポリエーテルブロックアミドは、米国特許第３，０４４，９７８号明細書等に開示されているように、それ自体は公知の物質である。
【００９２】
このものは、例えば、（イ）ジアミンとジカルボン酸の塩、ラクタム類又はアミノジカルボン酸（ＰＡ構成成分）、（ロ）ポリオキシエチレングリコール、ポリオキシプロピレングリコール等のポリオキシアルキレングリコール（ＰＧ構成成分）、及び（ハ）ジカルボン酸を重縮合させることによって製造される。
【００９３】
ポリエーテルブロックアミドの市販品としては、「ペバックス」（東レ（株）製商品名）、「ダイアミド−ＰＡＥ」（ダイセル・ヒュルス社製商品名）、「ＵＢＥポリアミドエラストマー」（宇部興産（株）製商品名）、「ノバミットＰＡＥ」（三菱化学（株）製商品名）、「グリラックスＡ」（大日本インキ化学工業（株）製商品名）、「グリロンＥＬＸ、ＥＬＹ」（エムスジャパン（株）製商品名）等がある。
【００９４】
（６） ウレタン系エラストマー
ポリウレタン系エラストマーは、ジイソシアネートと短鎖グリコール（エチレングリコール、プロピレングリコール、１，４−ブタンジオール、ビスフェノールＡ等）とからなるハードセグメントと、ジイソシアネートと長鎖ポリオールからなるソフトセグメントとを有するものである。ここで、長鎖ポリオールとしては、分子量が４００〜６，０００のポリ（アルキレンオキシド）グリコール、例えばポリエチレングリコール、ポリ（１，２及び１，３−プロピレンオキシド）グリコール、ポリ（テトラメチレンオキシド）グリコール、ポリ（ヘキサメチレンオキシド）グリコールなど、のようなポリエーテル系のもの、或いはポリアルキレンアジペート、ポリカプロラクトン、ポリカーボネート等のようなポリエステル系のものが使われる。この種のポリウレタン系熱可塑性エラストマーは下記一般式［II］で表される構造の化合物である。
【００９５】
【化２】

【００９６】
なお、この種のジイソシアネート化合物としては、フェニレンジイソシアネート、トリレンジイソシアネート、キシレンジイソシアネート、４，４’−ジフェニルメタンジイソシアネート、ヘキサメチレンジイソシアネート等の公知慣用のものを使用することができる。
【００９７】
前記ポリウレタン系エラストマーの市販品としては、「エラストラン」（武田バーディッシュウレタン社製商品名）、「ミラクトラン」（日本ミラクトラン（株）製商品名）、「レザミンＰ」（大日精化工業（株）製商品名）、「ユーファインＰ」（旭硝子（株）製商品名）等がある。
【００９８】
また、（Ｃ）成分として用いる熱可塑性エラストマーの曲げ弾性率（ＡＳＴＭＤ７９０）は、５００以下のものが望ましく、使用する（Ａ）成分の熱可塑性樹脂の曲げ弾性率（ＡＳＴＭ Ｄ７９０）の１／５以下、より望ましくは１／８以下の曲げ弾性率を有することが、エラストマーの添加による導電性の向上効果が大きい点で好ましい。
【００９９】
本発明において、このような（Ｃ）成分の配合量は、（Ａ）及び（Ｂ）成分の合計１００重量部に対して１〜３０重量部である。（Ｃ）成分の配合量がこれよりも少ないと、（Ｃ）成分を配合することによる発明の効果を十分に得ることができず、多いと、前述の如く、（Ａ）成分と（Ｃ）成分の分散相が反転して、（Ｃ）成分が海相となり、導電性が損なわれる。
【０１００】
（Ｃ）成分の配合量は、（Ｂ）成分に対する重量比で、０．１〜１０、望ましくは０．３〜５である。
【０１０１】
また、（Ｃ）成分の一部又は全量に、前述の(i)又は(ii)のような低Ｔｇ成分を用いる場合、この低Ｔｇ成分は（Ａ）及び（Ｂ）成分の合計１００重量部に対して５０重量部以下、望ましくは１〜２０重量部とすることが望ましい。低Ｔｇ成分の配合量がこれより少ないとその添加効果を十分に得ることができず、これより多いと得られる成形品の機械的強度や耐熱性を損なう点で望ましくない。
【０１０２】
更に、（Ｃ）成分中の低Ｔｇ成分の含有量としては、（Ｃ）成分１００重量部中、０．５〜８０重量部であると、導電性が均一となる点で望ましい。
【０１０３】
（Ｄ）添加成分
本発明に係る導電性熱可塑性樹脂組成物には、上記（Ａ）〜（Ｃ）成分の他、必要に応じて、上記の性能を損なわない範囲で付加成分を配合することができる。
【０１０４】
このような付加成分としては、例えば、ガラス繊維、シリカ繊維、シリカ・アルミナ繊維、チタン酸カリウム繊維、ホウ酸アルミニウム繊維等の無機繊維状強化材、アラミド繊維、ポリイミド繊維、フッ素樹脂繊維等の有機繊維状強化材、タルク、炭酸カルシウム、マイカ、ガラスビーズ、ガラスパウダー、ガラスバルーン等の無機充填剤、フッ素樹脂パウダー、二硫化モリブデン等の固体潤滑剤、パラフィンオイル等の可塑剤、酸化防止剤、熱安定剤、光安定剤、紫外線吸収剤、中和剤、滑剤、相溶化剤、防曇剤、アンチブロッキング剤、スリップ剤、分散剤、着色剤、防菌剤、蛍光増白剤等といった各種添加剤を挙げることができる。
【０１０５】
更に本発明に係る導電性熱可塑性樹脂組成物には、本発明で用いる微細炭素繊維以外の導電性フィラーを付加成分として添加しても良い。このような導電性フィラーとしては、例えばアルミニウム、銀、銅、亜鉛、ニッケル、ステンレス、真鍮、チタンなどの金属系フィラー、黒鉛（人工黒鉛、天然黒鉛）、ガラス状カーボン粒子、ピッチ系炭素繊維、ＰＡＮ系炭素繊維、酸化チタン、酸化亜鉛、酸化スズ、酸化インジウム等の金属酸化物系充填材などの導電性充填材が挙げられる。
【０１０６】
なお、金属酸化物系フィラーのなかでも格子欠陥の存在により余剰電子が生成して導電性を示すものの場合には、ドーパントを添加して導電性を増加させたものを用いても良い。例えば、酸化亜鉛にはアルミニウム、酸化スズにはアンチモン、酸化インジウムにはスズ等がそれぞれドーパントとして用いられる。また、炭素繊維などに金属をコーティングしたり、チタン酸カリウムウィスカやホウ酸アルミニウムウィスカの表面に導電性酸化スズ又は導電性カーボンを形成した複合系導電性フィラーを使用することもできる。
【０１０７】
（Ｅ）製造方法
本発明に係る導電性熱可塑性樹脂組成物は、通常の熱可塑性樹脂の加工方法で製造することができる。例えば（Ａ），（Ｂ）及び（Ｃ）成分と更に必要に応じて配合される添加成分の全てを予め混合した後、バンバリーミキサー、ロール、ブラベンダー、単軸混練押し出し機、二軸混練押し出し機、ニーダーなどで溶融混練することによって製造することができる。
【０１０８】
また、本発明の半導電性樹脂成形品は、このような導電性熱可塑性樹脂組成物を各種の溶融成形法を用いて成形することにより製造することができる。成形法としては、具体的には圧縮成形、押し出し成形、真空成形、ブロー成形、射出成形などを挙げることができる。これらの成形法の中でも、特に射出成形法、真空成形法において、顕著な効果を得ることができる。
【０１０９】
なお、本発明に係る導電性熱可塑性樹脂組成物を製造する際には、予め（Ａ）成分の一部に高濃度の（Ｂ）成分を添加したマスターバッチを製造し、その後このマスターバッチを（Ａ）成分と（Ｃ）成分で希釈して製造すると、（Ｃ）成分の分散相中に（Ｂ）成分の微細炭素繊維が過度に混入しないので、本発明の効果が大きくなる。また、（Ａ）成分の全量に（Ｂ）成分の全量を予め混合し、その後、（Ｃ）成分を添加して混合しても良い。
【０１１０】
本発明の半導電性樹脂成形品を、電子デバイス向け帯電防止部品として使用する場合には、表面抵抗値を１０^４〜１０^１０Ω、望ましくは１０^５〜１０^９Ωの範囲にコントロールすると、帯電が生じにくく、かつ接触電流が少ない点で好ましい。
【０１１１】
このような表面抵抗値の制御は、（Ｂ）成分の粘度、（Ａ）成分と（Ｂ）成分との粘度比、（Ｂ）成分及び（Ｃ）成分の配合割合や、成形条件（樹脂温度、金型温度、成形圧力等）を適宜調節し、（Ｂ）成分の微細炭素繊維の配向及びその緩和度合い、（Ｃ）成分の分散相による微細炭素繊維の導電性ネットワークの分断及び微細炭素繊維の配向の緩和の阻害の程度を制御すれば良い。
【０１１２】
なお、一般に表面抵抗値とは、測定サンプルの厚みや幅方向への電流の回り込みを考慮して、抵抗値を形状要因で換算することにより（Ω／□）の単位で得られるが、複雑な形状の成形品の場合、この換算が極めて困難である。一方、実用においては、形状を含んだ上での見かけの抵抗値が重要であり、必ずしも形状で換算された単位（Ω／□）を用いる必要はない。従って、本発明においては、上記表面抵抗値（Ω）で評価する。
【０１１３】
【実施例】
以下に実施例及び比較例を挙げて本発明をより具体的に説明する。
【０１１４】
なお、実施例及び比較例で用いた配合原料は次の通りである。
ポリカーボネート樹脂：三菱エンジニアリングプラスチック社製「ユーピロンＳ３０００」（商品名）（Ｔｇ＝１４６℃）
微細炭素繊維：ハイペリオンカタリシスインターナショナル社製 タイプ「ＢＮ」（商品名）（平均繊維径＝１０ｎｍ、平均繊維長＝０．５μｍ以上、長さ／径比＝５０以上、屈曲度＝１２２゜）
ＥＰＲ（エチレンプロピレン共重合体）：日本合成ゴム社製「ＥＰ９１２Ｐ」（商品名）（Ｔｇ＜−５０℃）
ＧＭＡ−ＰＥ（エチレングリシジルメタクリレート共重合体）：住友化学社製「ボンドファーストＥ」（商品名）（Ｔｇ＝−２３℃）
ＰＰ（ポリプロピレン）：日本ポリケム社製「ノバテック ＭＡ４Ｕ」（商品名）（Ｔｇ＝８℃）
ＰＥＴ（ポリエチレンテレフタレート）：日本ユニペット社製 ユニペット「ＲＴ５５３Ｃ」（商品名）（Ｔｇ＝８０℃）
ＰＥＩ（ポリエーテルイミド）：ＧＥプラスチックス社製「ウルテム １０００」（Ｔｇ＝２１８℃）
ＰＡＲ（ポリアリレート樹脂）：ユニチカ株式会社製「Ｕポリマー Ｕ１００」（商品名）（Ｔｇ＝１８２℃）
【０１１５】
実施例１〜５，比較例１〜４
表１に示す成分配合で各材料を混合し、２軸押出機（池貝鉄鋼社製「ＰＣＭ４５」、Ｌ／Ｄ＝３２（Ｌ；スクリュー長、Ｄ；スクリュー径））を用いて、バレル温度３００℃（ただし、実施例５及び比較例４は３５０℃）、スクリュー回転数１６０ｒｐｍにて溶融混練して、導電性ポリカーボネート樹脂組成物のペレットを得た。
【０１１６】
なお、配合混練は、予めポリカーボネート樹脂に微細炭素繊維を１５重量％添加したマスターバッチを製造し、これを残る成分で希釈して所定の配合量とした。
【０１１７】
得られた導電性熱可塑性樹脂組成物について、成形品の表面抵抗値と、分散相の短径及びアスペクト比を下記方法により測定し、結果を表１に示した。
【０１１８】
▲１▼ 表面抵抗値
各導電性熱可塑性樹脂組成物を用いて、７５ｔｏｎ射出成型機にて、シリンダ温度３１０℃、金型温度９０℃で射出速度１５〜１７ｃｃ／ｓｅｃにて、図４に示す抵抗値測定用シートサンプル１０を成形した。この抵抗値測定用シートサンプル１０について、ゲート部（フィルムゲート側）１０Ａ、末端部１０Ｂの表面抵抗値をダイヤインスツルメント社製ハイレスタＵＰを使用して、ＵＡプローブ（２探針プローブ、プローブ間距離２０ｍｍ、プローブ直径２ｍｍ）を用いて測定した。印可電圧は抵抗値１×１０^６Ω未満であれば１０Ｖとし、抵抗値１×１０^６Ω以上であれば１００Ｖとして測定を行った。
【０１１９】
▲２▼ 分散相の短径及びアスペクト比
▲１▼の抵抗値測定用シートサンプル１０の表面抵抗値測定部１０Ａ，１０Ｂについて、（Ｃ）成分の分散相の短径及びアスペクト比を測定した。
【０１２０】
なお、微細炭素繊維を含有する射出成形品は、その表面近傍において最も剪断力が大きく、冷却速度が速く、その結果導電性が低くなる。従って、成形品の表面抵抗値や実用的な帯電特性は、表面近傍の分散状態に支配される。そこで、この分散相の短径及びアスペクト比の測定では、表面から５０μｍの深さの範囲で分散相を観察した。
【０１２１】
また、（Ｃ）成分の分散相形状は、樹脂の流動方向に沿って細長く引き延ばされていることが確認され、そのため流動方向が最も大きく、また深さ方向が最も小さい直径となることが確認された。従って、分散相の直径を流動方向に測定した値を長径、深さ方向に測定した値を短径とした。
【０１２２】
以上より、サンプルから樹脂の流動方向に沿った断面の薄切片を切り出し、これを染色処理した後に、透過型電子顕微鏡にて分散相を観察し、分散相の３０個をランダムに選び、それぞれ短径及び長径を測定し、その平均値を算出した。
【０１２３】
なお、この顕微鏡観察において、（Ｃ）成分の分散相中に微細炭素繊維が殆ど存在しないことを確認した。
【０１２４】
また、実施例１及び比較例１，２で用いた導電性ポリカーボネート樹脂組成物について、導電性の成形温度依存性を下記方法により調べ、結果を表２に示した。また、表面抵抗値と成形温度との関係を図５に示した。
【０１２５】
▲３▼ 導電性の成形温度依存性
実施例１、比較例１及び比較例２で用いた組成物を用いて、▲１▼の抵抗値測定用シートサンプル１０を射出成形する際の成形温度を変化させることで、冷却速度を変えて成形を行った（金型温度９０℃ 射出速度１５〜１７ｃｃ／ｓｅｃ）。次に、得られたシートサンプル１０の中央部１０Ｃにおいて、表面抵抗値、及び、（Ｃ）成分の分散相の短径（実施例１のものについてのみ）を上記▲１▼，▲２▼と同様に測定した。
【０１２６】
【表１】

【０１２７】
【表２】

【０１２８】
表１，２及び図５から、次のことが明らかである。
【０１２９】
即ち、実施例１〜５の本発明の半導電性樹脂成形品であれば、抵抗値１０^４〜１０^１０Ωの半導電性領域において、極めて均一な導電性の分布を得ることができ、しかも、導電性の射出成形温度の依存性も小さく、どのような条件でも安定した半導電性を得ることができる。
【０１３０】
これに対して、比較例１〜３では、均一な半導電性を得ることができない。
【０１３１】
特に、実施例５と比較例３との比較から分かるように、同一の組成物配合であっても（Ｃ）成分の分散相の短径が本発明の範囲外であると、本発明による効果が得られない。
【０１３２】
また、比較例４のように、（Ｃ）成分が（Ａ）成分と相溶し、その結果（Ｃ）成分が１０μｍ以上の分散相を形成しない場合、導電性のばらつきが大きく、本発明の効果は得られない。
【０１３３】
【発明の効果】
以上詳述した通り、本発明によれば、抵抗値１０^４〜１０^１０Ωの半導電性領域において、均一な導電性を有する半導電性樹脂成形品が提供される。
【図面の簡単な説明】
【図１】（ａ）図は実施の形態に係る半導電性樹脂成形品の海島構造を示す模式的な断面図であり、（ｂ）図は（Ｃ）成分の分散相を示す模式的な断面図である。
【図２】微細炭素繊維による導電性ネットワークを説明する模式図である。
【図３】本発明に係る微細炭素繊維の屈曲度の測定方法の説明図である。
【図４】実施例及び比較例において成形した抵抗値測定用シートサンプルを示す平面図である。
【図５】実施例１及び比較例１，２における導電性の成形温度依存性を示すグラフである。
【符号の説明】
１ （Ａ）成分（マトリックス樹脂）
２ 微細炭素繊維（（Ｂ）成分）
３ （Ｃ）成分
１０ 抵抗値測定用シートサンプル[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a semiconductive resin molded article, for example, the electric and electronic fields and the automobile field, more specifically, semiconductive rollers and belts for copying machines and printers, various antistatic materials, especially electronic devices. The present invention relates to a semiconductive resin molded article having a uniform resistance value in a semiconductive region, which is suitable for antistatic parts such as trays, cases, jigs and tools in manufacturing and conveying processes.
[0002]
[Prior art]
In recent years, as electronic devices such as magnetic heads of hard disk drives have been remarkably increased in density, destruction due to ESD (electrostatic discharge) phenomenon of devices has become serious. As a result, antistatic parts such as device transport trays and jigs are required not only to dissipate charged charges quickly, but also to have low contact current when the device contacts the antistatic parts. It has become like this. That is, these antistatic components are required to have a semiconductivity that is controlled within an appropriate range, with a surface electrical resistance value that is neither too high nor too low.
[0003]
Conventionally, as a semiconductive part, a molded resin composition in which a conductive component such as carbon black, carbon fiber, and hydrophilic polymer is added to a thermoplastic resin has been used.⁴-10¹⁰The semiconductive region of Ω greatly depends on the amount of conductive component added and the molding conditions, and it is difficult to precisely control the semiconductivity.
[0004]
On the other hand, such antistatic parts for electronic devices not only have semiconductivity whose electric resistance value is controlled within an appropriate range, but also have less dust generation due to dropping of the conductive filler from the surface of the molded product. In response to this requirement, it is considered that a material obtained by adding fine carbon fibers to a thermoplastic resin is appropriate (Japanese Patent Publication No. 8-508534, etc.). However, even in this case, it is difficult to control the resistance value to a sufficiently narrow semiconductive region because the resistance value greatly depends on molding conditions and the like.
[0005]
[Problems to be solved by the invention]
An object of the present invention is to solve the above-described conventional problems and provide a semiconductive resin molded product having a uniform resistance value in a semiconductive region.
[0006]
[Means for Solving the Problems]
  The semiconductive resin molded article of the present invention comprises (A) a matrix thermoplastic resin and (B) 100 parts by weight of a conductive resin component comprising 0.1 to 20% by weight of fine carbon fibers having an average fiber diameter of 200 nm or less. , (C) thermoplastic resins other than the component (A) and / or thermoplastic elastomer 0.130Parts by weightThe blending amount of the component (C) is 0.1 to 10 by weight ratio to the component (B).A semiconductive resin molded product obtained by molding a conductive thermoplastic resin composition formed by mixing, and the component (C) is dispersed in a sea island shape without being completely compatible with the component (A). The component (C) forms an island-shaped dispersed phase, the average value of the minor axis of the dispersed phase of the component (C) is 10 μm or less, and the minor axis of the dispersed phase of the component (C) The average value is not less than 2 times and not more than 200 times the average fiber diameter of the fine carbon fibers of the component (B), and the ratio (major axis / minor axis) of the minor axis to the major axis of the dispersed phase of the component (C) is It is 50 or less, and the fine carbon fiber of the said (B) component does not exist substantially in this (C) component, It is characterized by the above-mentioned.
[0007]
Fine carbon fibers having an average fiber diameter of 200 nm or less can exhibit electrical conductivity with a slight addition amount compared to conventional carbon fibers and carbon black, and thus are excellent in low dust generation, appearance of molded products, and moldability. In this respect, it is known as an excellent conductive filler.
[0008]
However, the thermoplastic resin molded article containing such fine carbon fibers has its conductivity easily fluctuated greatly depending on the molding process conditions, and it has been difficult to uniformly control the resistance value of the semiconductive region. . As a result of examining the reason for this, the present inventor has come to the following conclusion.
[0009]
That is, in a thermoplastic resin molded article containing fine carbon fibers, the fine carbon fibers are dispersed and exist in an entangled state in the thermoplastic matrix resin, and the entangled fine carbon fibers are more conductive. Conductivity develops when a network is formed.
[0010]
This thermoplastic resin molded product is molded through a process of melting, flowing, cooling and solidifying by a molding process such as injection molding of a thermoplastic resin composition containing fine carbon fibers. As a result, as shown in FIG. 2A, as a result of the orientation of the fine carbon fibers 2 in the matrix resin 1, the entanglement and contact between the fine carbon fibers 2 become insufficient, and the conductivity becomes low.
[0011]
Next, the fine carbon fibers 2 oriented in the matrix resin 1 are subjected to FIG. 2B and further to FIG. 2C while the temperature of the matrix resin 1 is high (viscosity is low) in the initial stage of the cooling and solidification process. As shown, the orientation is relaxed and a conductive network is formed, and as a result, the conductivity is improved. This phenomenon is verified by improving the conductivity of the heated portion by heating again a molded product having low conductivity (high resistance value) molded under the condition in which the fine carbon fibers 2 are extremely oriented. Is done. This phenomenon occurs not only in the molding process in which the resin is completely melted and fluidized, such as injection molding and extrusion molding, but also in the molding method in which a semi-molten sheet is stretched and molded as in vacuum molding. The same occurs, and the conductivity (resistance value) varies due to the orientation of the fine carbon fibers in the stretching process and the relaxation of the orientation in the cooling process.
[0012]
In order to control the conductivity of the molded product to the semiconductive region based on the above-described conductivity expression mechanism, it is necessary to form an appropriate contact state without excessive progress of orientation and relaxation of the fine carbon fibers. is there. That is, for example, in the state where the fine carbon fibers 2 are sufficiently oriented as shown in FIG.¹²In a state where it has a low conductivity of Ω or more and the orientation of the fine carbon fiber 2 is sufficiently relaxed as shown in FIG.⁴Since the conductivity is less than Ω, 10⁴-10¹⁰In order to obtain semiconductivity in the range of Ω, it is desired that the orientation of the fine carbon fibers 2 is moderately relaxed in the state as shown in FIG. However, 10⁴-10¹⁰In order to obtain the conductivity of the semiconductive region of Ω, moderately reorienting the orientation of the fine carbon fiber is because the orientation of the fine carbon fiber and the state of its relaxation change particularly sensitively to the molding conditions. It is difficult to realize with good reproducibility, and in a molded product having a complicated shape, the resistance value varies depending on the part even in the same molded product, and the resistance value of each part is controlled uniformly. It is also extremely difficult.
[0013]
For example, in an injection molded product, in the vicinity of the gate, which is a resin injection port, or in a thin portion, a fine carbon fiber is easily oriented due to a large shearing force, and the conductivity tends to be low (resistance value is high). Since the shear force is low at the flow end, the orientation of the fine carbon fiber is low and the conductivity is high (resistance value is low). If the cooling rate is reduced or the amount of fine carbon fiber added is increased in order to improve the electrical conductivity in the vicinity of the gate (decrease the resistance value), the resistance value at the flow end decreases, resulting in a uniform resistance value. Sex cannot be secured. In general, the shear rate and the cooling rate increase near the surface of the molded product and are easily affected by the molding conditions. Therefore, in many semiconductive resin molded products such as antistatic parts, the fluctuation of the surface resistance value tends to be particularly large.
[0014]
The present inventor has studied in order to stably obtain a semi-conductive molded product, based on the orientation of fine carbon fibers in the molding process and the mechanism of conductivity development due to the relaxation of the orientation. It was found that good semiconductivity can be realized by forming an island-like dispersed phase of component (C) in the matrix resin.
[0015]
That is, in the present invention, as shown in FIG. 1A, the orientation of the fine carbon fibers in the matrix resin is prevented from being excessively relaxed in the cooling process, as shown in FIG. (2) Non-conductive or low-conductivity second resin and / or elastomer (C) component 2 which is different from component matrix resin 1 is formed into a sea-island shape without being compatible with (A) component 1 of the matrix resin. The semiconductive property is realized by dispersing and electrically dividing the conductive network of the fine carbon fiber 2 by the dispersed phase of the component (C) 3. Thus, in order to divide the conductive network of the fine carbon fiber 2 by the dispersed phase of the component (C), in the present invention, as shown in FIG. It is desirable that the fine carbon fiber 2 is not substantially present in the component 1) and the component 3 is dispersed in the component (C).
[0016]
As a method for confirming that the fine carbon fiber 2 is not substantially present in the (C) component 3, for example, after removing the (C) component by etching the cross section of the molded product, (C) It is only necessary to confirm that fine carbon fibers are not present (a network is not formed) in the portion after the component is removed.
[0017]
The dispersed phase of component (C) exhibits the effect of partially disrupting the conductive network formed by the fine carbon fibers and the effect of inhibiting the relaxation of the orientation of the fine carbon fibers during the cooling process. It is possible to prevent the property from becoming excessively high (the resistance value becomes excessively low).
[0018]
As a result, even if the cooling rate is decreased or the amount of fine carbon fiber added is increased in order to improve the conductivity (reducing the resistance value) in the vicinity of the gate of the injection molded product or the thin-walled portion, An excessive increase in conductivity (decrease in resistance value) does not occur at the end or the like, and a semiconductive resin molded product having a uniform resistance value can be obtained.
[0019]
FIG. 1B shows the dispersed phase of component (C) 3 dispersed in component (A). The size and shape of the dispersed phase vary depending on the viscosity of the component (C), the viscosity ratio of the component (C) and the component (A), compatibility, kneading conditions during production, and the like. In addition, the dispersed phase of component (C) may be stretched in the flow direction during the flow of molding to form a dispersed phase that is oriented in the form of fibers or layers.
[0020]
The size of the dispersed phase of the component (C) in the present invention is a value measured at the point where the minor axis of the dispersed phase (that is, the diameter becomes minimum. R in FIG. 1B)._min) Is 10 μm or less. (C) Short diameter R of dispersed phase of component_minIf it is larger than 10 μm, the effect of the present invention cannot be obtained, and the conductivity is excessively increased (the resistance value is excessively decreased).
[0021]
The reason will be described below.
[0022]
That is, if the minor diameter of the dispersed phase of component (C) is large and the dispersed state is rough at the same proportion of component (C), the distance between the dispersed phases increases as a result. Since there is no effect of inhibiting the relaxation of fine carbon fibers or the effect of dividing the conductive network in the part where the interval between the dispersed phase and the dispersed phase, that is, the component (C) does not exist, an excessive increase in conductivity cannot be prevented. . Therefore, in order to obtain the effect of the present invention, it is necessary to add a large amount of the component (C). However, the addition of a large amount of the component (C) not only decreases the strength of the obtained molded product, The sea-island phase of component (A) and component (C) is reversed, component (C) becomes the sea phase, component (A) containing fine carbon fibers becomes the dispersed phase (islands), and the conductive network of fine carbon fibers becomes Not formed, causing an extreme decrease in conductivity.
[0023]
For this reason, the dispersion phase of the component (C) inhibits the relaxation of the orientation of the fine carbon fibers, and in order to appropriately divide the conductive network of the fine carbon fibers, the short diameter R of the dispersion phase._minIs as small as 10 μm or less. However, when the component (C) is molecularly compatible with the component (A) and dispersed completely uniformly, the effect of inhibiting the relaxation of the fine carbon fibers and the effect of dividing the conductive network of the fine carbon fibers are obtained. Thus, the effect of the present invention cannot be obtained.
[0024]
In the present invention, the minor axis R of the dispersed phase of the component (C)_minIs preferably 2 times or more and 200 times or less, particularly 2 times or more and 50 times or less of the average fiber diameter of the fine carbon fibers, from the viewpoint of uniform semiconductivity.
[0025]
When the disperse phase of component (C) is in the shape of a fiber or layer, the minor axis R_minAnd the major axis (value measured at the point where the diameter becomes maximum. R in FIG. 1B)_max), That is, the aspect ratio (major axis / minor axis) is preferably 50 or less, particularly 30 or less. If the aspect ratio is larger than this, the effect of dividing the conductive network of fine carbon fibers becomes too great, and the conductivity is extremely lowered, which is not desirable.
[0026]
In the present invention, the minor axis and aspect ratio of the dispersed phase of component (C) are the average of values measured at 30 points using a microscope.
[0027]
The average distance between the dispersed phases of the component (C) is preferably 10 times or more and 10,000 times or less the average diameter of the fine carbon fibers from the viewpoint of uniform semiconductivity.
[0028]
Furthermore, as a part or all of the component (C), it is only necessary to prevent an excessive increase in conductivity by using a component having a viscosity increase in the cooling process and a solidification rate much slower than the component (A). In addition, an excessive decrease in conductivity (an increase in resistance value) can be improved.
[0029]
That is, for example, the low conductivity portion (high resistance portion) such as the vicinity of the gate of an injection molded product is not completely relaxed within the time until the resin in the cooling process is solidified due to the extreme orientation of the fine carbon fibers. It will occur. On the other hand, by slowing the solidification rate of all or part of the component (C), the relaxation of the orientation of the fine carbon fibers around the component (C) can be promoted, and the resistance value can be stabilized.
[0030]
In order to express the above effect, the thermoplastic resin and / or the thermoplastic elastomer (hereinafter referred to as “the (C) component”) having a glass transition temperature (Tg) as shown in (i) or (ii) below. It may be referred to as “low Tg component”).
(i) When component (A) is an amorphous resin, a thermoplastic resin and / or thermoplastic resin having a glass transition temperature (Tg) that is 120 ° C. or more lower than the glass transition temperature (Tg) of component (A) Elastomer
(ii) When component (A) is a crystalline resin, a thermoplastic resin and / or thermoplastic elastomer having a glass transition temperature (Tg) that is 200 ° C. or lower than the crystalline melting point (Tm) of component (A)
[0031]
In the present invention, it is preferable to use a polycarbonate resin having a good balance of dimensional accuracy, heat resistance, mechanical properties and the like as the thermoplastic resin.
[0032]
In addition, the said effect by the dispersed phase of (C) component by this invention is achieved in combination with a fine carbon fiber with an average fiber diameter of 200 nm or less as a conductive filler. In the molded product of the resin composition to which more conductive fillers such as carbon fibers and metals are added, there is little entanglement between the conductive fillers, so that the effect of relaxing the orientation and forming the conductive network in the cooling process is extremely small. Therefore, the above effect due to the addition of the component (C) is low.
[0033]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the semiconductive resin molded product of the present invention will be described in detail.
[0034]
First, the components of the conductive thermoplastic resin composition, which is a molding material for the semiconductive resin molded product of the present invention, will be described.
[0035]
(A) Thermoplastic resin
Examples of the thermoplastic resin of component (A) include polycarbonate, polyarylate, polyphenylsulfone, polyethersulfone, polyetherimide, polyoxymethylene, polystyrene, alicyclic polyolefin, polyethylene, polypropylene, polymethylpentene, Examples thereof include thermoplastic resins such as polyethylene terephthalate, polybutylene terephthalate, polyphenylene sulfide, polyamide, and polyetheretherketone. One or more of these can be appropriately selected and used from the characteristics such as mechanical strength and moldability according to the use of the semiconductive resin molded product.
[0036]
Among the thermoplastic resins described above, examples of the amorphous thermoplastic resin include polycarbonate, polyarylate, polyphenylsulfone, polyethersulfone, polyetherimide, modified polyoxymethylene, polystyrene, and alicyclic polyolefin. On the other hand, examples of the crystalline thermoplastic resin include polyethylene, polypropylene, polymethylpentene, polyethylene terephthalate, polybutylene terephthalate, polyphenylene sulfide, and polyamide.
[0037]
Among such thermoplastic resins, a polycarbonate resin is desirable in terms of a good balance of dimensional accuracy, heat resistance, mechanical properties, and the like. As polycarbonate resin, for example, a general one produced by reacting a raw material mainly composed of a dihydric phenol compound with phosgene by a solution method such as an interfacial polymerization method, a pyridine method, or a chloroformate method is used. can do.
[0038]
When a polycarbonate resin is used as the thermoplastic resin, the melt flow rate (MFR) of the polycarbonate resin is 2 g / 10 min or more and 30 g / 10 min or less, particularly 4 g / 10 min or more and 15 g in the measurement of 280 ° C. and 2.16 kg load. / 10 minutes or less is desirable.
[0039]
(B) Fine carbon fiber
The fine carbon fiber of the component (B) used in the present invention has an average fiber diameter of 200 nm or less, and is generally produced by a vapor growth method. As the fine carbon fiber, for example, carbon fibrils described in JP-T-8-508534 are used.
[0040]
That is, the carbon fibril has a graphite outer layer deposited substantially concentrically along the columnar axis of the fibril, and the fiber central axis is not linear but has a undulating and winding tubular form. .
[0041]
The average fiber diameter of carbon fibrils is 200 nm or less, desirably 100 nm or less, and more desirably 50 nm or less. The fiber diameter of carbon fibrils depends on the production method of carbon fibrils and has a slight distribution. The average fiber diameter referred to here is an average value measured at five points under a microscope.
[0042]
If the average fiber diameter of the carbon fibrils is larger than 200 nm, the contact between the fibrils in the matrix resin becomes insufficient, so that a large amount of addition is necessary to develop conductivity, and stable conductivity is difficult to obtain. .
[0043]
The average fiber diameter of carbon fibrils is preferably 0.1 nm, particularly 0.5 nm or more. If the average fiber diameter is smaller than this, the production is extremely difficult.
[0044]
Carbon fibrils preferably have a length-to-diameter ratio (length / diameter ratio, that is, aspect ratio) of 5 or more, and particularly those having a length / diameter ratio of 100 or more are easy to form a conductive network. The addition of a small amount is desirable in that excellent conductivity can be obtained. A more preferable length / diameter ratio of the carbon fibril is 1000 or more. In addition, the fiber diameter and fiber length (and aspect ratio) of this carbon fibril are the average values of 10 actually measured values when observed with a transmission electron microscope.
[0045]
The wall thickness of carbon fibrils having a fine tubular form (wall thickness of the tubular body) is usually about 3.5 to 75 nm. This usually corresponds to about 0.1 to 0.4 times the outer diameter of the fibril.
[0046]
When at least a part of the carbon fibril is in the form of an aggregate, the resin composition as a raw material does not contain a fibril aggregate having a diameter of about 50 μm, particularly larger than 10 μm, measured on an area basis. However, the addition amount for obtaining the predetermined conductivity is small, and it is desirable in that the mechanical properties of the obtained molded product are not deteriorated.
[0047]
Furthermore, in the present invention, the fine carbon fibers such as carbon fibrils have a twisted fiber shape, and the entanglement between the fibers increases, and conductivity is obtained with a small amount of addition, and at the same time, the effects of the present invention are achieved. Desirable in large respects.
[0048]
In order to obtain such entanglement, the fine carbon fiber used in the present invention preferably has a bending degree of 5 ° or more, desirably 20 ° or more, and more desirably 40 ° or more.
[0049]
The degree of bending of the fine carbon fiber is, for example, by removing the resin component of the semiconductive resin molded product of the present invention with a solvent, ion sputtering or the like to expose the fine carbon fiber, or an ultrathin slice cut out from the molded product Can be measured by observation with an electron microscope. In this case, fine carbon fibers in the surface layer within 50 μm from the surface of the molded product are measured.
[0050]
As shown in FIG. 3, the degree of bending is observed with a microscope for fine carbon fibers 2 such as carbon fibrils, and on the same fiber, the fiber diameter is measured five times (fiber diameter (part d in FIG. 2)). 2) Select any two points A and B that are far apart (by measuring along the fiber) and tangent L to each point._A, L_BTangent L_A, L_BThe outside angle (point indicated by α in FIG. 2) of the point Q where the crossing points are measured. The average value of 10 points is taken and this is defined as the degree of bending.
[0051]
This angle is 0 ° if the fiber is straight, 180 ° if it is a semicircle, and 360 ° if it is a circle.
[0052]
If the degree of flexure α obtained by performing such measurement is 5 ° or more, preferably 20 ° or more, and more preferably 40 ° or more, a network formed by entanglement of the fine carbon fibers can be easily formed. In terms of preventing non-conductive fibers from falling off and imparting antistatic properties, it is preferable.
[0053]
Note that ordinary carbon fibers (pitch-based and PAN-based) are rigid and linear fibers having a fiber diameter of about 7 to 13 μm, and the degree of bending is less than 5 °. Such straight fibers are not entangled with each other and it is difficult to form a network structure.
[0054]
In the present invention, as the fine carbon fibers, commercially available products such as “BN” manufactured by Hyperion Catalysis International, Inc. can be used.
[0055]
The fine carbon fiber used in the present invention may be subjected to treatment with the thermoplastic resin of component (A), or various surface treatments and dispersants. As the treating agent in this case, for example, a coupling agent such as a silane coupling agent, a titanate coupling agent, an aluminum coupling agent, a nonpolar segment and a polar segment block or graft copolymer, and the like can be used. .
[0056]
In the present invention, the content of the fine carbon fiber is 0.1 to 20% by weight, preferably 0 in the total conductive resin component of the thermoplastic resin (A) and the fine carbon fiber (B). .5-8% by weight. If the content of the fine carbon fiber is less than this range, sufficient antistatic performance cannot be obtained for the obtained molded product, and if the content of the fine carbon fiber is more than this range, the moldability is deteriorated. There is a risk of causing deterioration in physical properties such as strength of the molded product.
[0057]
(C) Thermoplastic resin and / or thermoplastic elastomer
As the component (C), in addition to the thermoplastic resins mentioned as the thermoplastic resin that can be used as the component (A), various thermoplastic elastomers such as olefin elastomers, styrene elastomers, ester elastomers, and amide elastomers. Urethane elastomers can be used.
[0058]
(C) component should just differ from the thermoplastic resin selected as (A) component among these thermoplastic resins and / or thermoplastic elastomers, and even if it uses 1 type, it combines 2 or more types. May be used.
[0059]
In order to disperse the component (C) in the component (A) so that the minor axis of the dispersed phase of the component (C) is 10 μm or less, the component (C) is relatively compatible with the component (A). It is desirable to use a good one.
[0060]
For example, when a polycarbonate resin is used as the component (A), it is desirable to use a component having a polar group as the component (C). Specifically, polybutylene terephthalate, polyethylene terephthalate, polyarylate, polysulfone, polyethersulfone, polyetherimide, polyamide, ester elastomer, amide elastomer, urethane elastomer, glycidyl group, carboxylic acid, silanol group, etc. Examples thereof include polar group-modified polyolefin modified with a polar group and polar group-modified polystyrene. Moreover, when using nonpolar components, such as polyolefin, polystyrene, an olefin-type elastomer, and a styrene-type elastomer, it is desirable to use together compatibilizing components, such as the above-mentioned polar group modified material and a silane coupling agent.
[0061]
Among the polar group-modified products, examples of the glycidyl-modified product include ethylene-glycidyl methacrylate copolymer, ethylene-glycidyl methacrylate-graft-polymethyl methacrylate, and ethylene-glycidyl methacrylate-graft-polystyrene.
[0062]
Examples of the acid-modified product include maleic anhydride, fumaric acid, acrylic acid for nonpolar resins such as polyethylene, polypropylene, ethylene-propylene copolymer, ethylene butene copolymer, polystyrene, and styrene elastomer. And those obtained by melting and grafting an unsaturated carboxylic acid such as methacrylic acid in the presence of a radical generator such as an organic peroxide.
[0063]
Examples of silanol-modified products include, for example, the general formula: RSiR ′_nY_3-nWherein R is an ethylenically unsaturated hydrocarbon or oxyhydrocarbon group, R ′ is an aliphatic saturated hydrocarbon group, Y is a hydrolyzable organic group, and n is 0, 1 or 2. Examples thereof include those obtained by melt-mixing the ethylenically unsaturated silane compound represented in the presence of a radical generator such as an organic peroxide.
[0064]
In addition, as a low Tg component having a Tg lower by 120 ° C. than Tg (140 to 150 ° C.) of a polycarbonate resin, polyethylene, polypropylene, olefin elastomer, styrene elastomer, ester elastomer, amide elastomer, urethane elastomer And various elastomers.
[0065]
Anti-static parts for electronic devices, especially magnetic jigs for hard disk drives, and fixing jigs used for fixing and protecting the heads in the transport holder must be not only semiconductive but also less dusty. In addition, it is required to have excellent slidability with the head. When the semiconductive resin molded article of the present invention is used for such applications, when the whole or part of the polar group-modified polyolefin such as glycidyl group is used as the component (C), not only the stable semiconductive property is obtained. It is preferable because it generates less dust due to falling off of the dispersed phase and is excellent in slidability.
[0066]
Hereinafter, various elastomers of the component (C) will be described.
[0067]
(1) Olefin-based elastomer (olefin-based TPE)
As the olefinic TPE, for example, an olefinic copolymer rubber, specifically an ethylene / propylene copolymer rubber (EPM), an ethylene / propylene / nonconjugated diene copolymer rubber (EPDM), etc. And an elastic body of an amorphous random copolymer, or an elastic body obtained by heat-treating them in the presence of an organic peroxide and mainly crosslinked by radicals.
[0068]
Examples of such olefin copolymer rubber include the above-mentioned ethylene / propylene copolymer rubber (EPM), ethylene / 1-butene copolymer rubber (EPM), and non-conjugated dienes such as butene-1, 1,4- Mention may be made of ethylene / propylene / non-conjugated diene copolymer rubbers using aliphatic dienes such as hexadiene, 5-ethylidene norbornene, 5-methylnorbornene, 5-vinyl norbornene, dicyclopentadiene, dicyclooctadiene and the like.
[0069]
The production method and shape of these ethylene / propylene copolymer rubbers are not particularly limited.
[0070]
(2) Styrenic plastic elastomer (styrene TPE)
Examples of styrene-based TPE include hydrogenated styrene / butadiene block copolymers, hydrogenated styrene / isoprene block copolymers, or hydrogenated styrene / conjugated diene block copolymers selected from mixtures thereof. Can be mentioned as a basic component.
[0071]
The hydrogenated styrene / conjugated diene block copolymer is a hydrogenated styrene / butadiene block copolymer, a hydrogenated styrene / isoprene block copolymer, or a mixture thereof. Examples thereof include styrene / ethylene / butylene / styrene copolymers, or styrene / ethylene / propylene / styrene copolymers which are hydrogenated products of styrene / isoprene block copolymers, or mixtures thereof.
[0072]
(3) Additional compounding material (optional component)
The above-mentioned olefin-based and styrene-based elastomer components have a hydrocarbon rubber softener (average molecular weight of 300 to 2,000), various thermoplastic resins, various elastomers, talc, and the like within a range that does not significantly impair the effects of the present invention. Compounding materials such as various fillers such as calcium carbonate, glass fiber, and glass balloon can be blended.
[0073]
The hydrocarbon rubber softener can play an important role in controlling the flexibility of the olefin-based or styrene-based elastomer composition.
[0074]
Such a hydrocarbon rubber softener (having an average molecular weight of generally 300 to 2,000, preferably 500 to 1,500) is a hydrogen of olefin copolymer rubber or styrene / conjugated diene block copolymer. It is preferable to blend 0 to 250 parts by weight, particularly 20 to 200 parts by weight with respect to 100 parts by weight of the additive. Such a hydrocarbon rubber softener is a mixture of a combination of an aromatic ring, a naphthene ring and a paraffin ring, and the paraffin chain carbon number accounts for 50% or more of the total carbon. These are called oils, and those having a naphthenic ring carbon number of 30 to 45% are called naphthenic oils, and those having more than 30% aromatic carbons are called aromatic oils. Among these, it is preferable to use paraffinic oil.
[0075]
Examples of the thermoplastic resin in the additional compounding component include polyolefin resins such as polypropylene, ethylene resin, and polybutene-1 resin, polystyrene, acrylonitrile / styrene copolymer, acrylonitrile / butadiene / styrene copolymer, and the like. Polystyrene resins such as polystyrene resins, polyphenylene ether resins, polyamide resins such as nylon 6 and nylon 66, polyester resins such as polyethylene terephthalate and polybutylene terephthalate, polyoxymethylene resins such as polyoxymethylene homopolymers and polyoxymethylene copolymers, A polymethyl methacrylate resin or the like can be used.
[0076]
Examples of the ethylene resin include polyethylene, ethylene / α-olefin copolymer, ethylene / vinyl acetate copolymer, ethylene / (meth) acrylic acid copolymer, and ethylene / (meth) acrylic acid ester copolymer. be able to.
[0077]
Examples of the polyethylene include low density polyethylene (branched ethylene polymer), medium density, high density polyethylene (linear ethylene copolymer), and the like.
[0078]
As the above-mentioned ethylene / α-olefin copolymer, ethylene / butene-1 copolymer, ethylene / hexene copolymer, ethylene / heptene copolymer, ethylene / octene copolymer, ethylene / 4-methylpentene- One copolymer can be cited as a representative example.
[0079]
The thermoplastic resin to be used may be one kind or plural kinds, and the addition amount is generally 1 to 100 parts by weight of the hydrogenated product of olefin copolymer rubber or styrene / conjugated diene block copolymer. It is preferable to blend 300 parts by weight, preferably 20 to 250 parts by weight.
[0080]
(4) Ester elastomer
As the ester elastomer, polyester polyester block copolymer using aromatic polyester as hard component, polyester polyether block copolymer using aliphatic polyether as soft component, aromatic polyester as hard component, and aliphatic polyester as soft component A copolymer is mentioned.
[0081]
The polyester polyether block copolymer comprises (1) an aliphatic and / or alicyclic diol having 2 to 12 carbon atoms, (2) an aromatic dicarboxylic acid or an alkyl ester thereof, and (3) a weight average molecular weight of 400. ˜6000 polyalkylene ether glycol as a raw material, and an oligomer obtained by esterification reaction or transesterification reaction is polycondensed.
[0082]
Here, as the aliphatic and / or alicyclic diol having 2 to 12 carbon atoms, a known material can be used as a raw material for polyester, particularly a polyester elastomer. For example, ethylene glycol, propylene glycol, trimethylene Glycol, 1,4-butanediol, 1,4-cyclohexanediol, 1,4-cyclohexanedimethanol and the like, preferably 1,4-butanediol, ethylene glycol, particularly preferably 1,4-butanediol As a main component, one kind or two or more kinds can be used.
[0083]
As the aromatic dicarboxylic acid, known raw materials for polyester, particularly polyester elastomer, can be used, and examples thereof include terephthalic acid, isophthalic acid, phthalic acid, 2,6-naphthalenedicarboxylic acid, and the like. Terephthalic acid and 2,6-naphthalenedicarboxylic acid, particularly preferably terephthalic acid is the main component, and two or more of these may be used in combination. Examples of the alkyl ester of aromatic dicarboxylic acid include dimethyl esters such as dimethyl terephthalate, dimethyl isophthalate, dimethyl phthalate, and 2,6-dimethyl naphthalate, preferably dimethyl terephthalate and 2,6-dimethyl naphthalate. In particular, dimethyl terephthalate is preferable, and two or more of these can be used in combination. In addition to the above, trifunctional diols, other diols and other dicarboxylic acids and esters thereof may be copolymerized in small amounts, and aliphatic dicarboxylic acids such as adipic acid or alicyclic dicarboxylic acids, or Alkyl esters and the like may also be used as copolymerization components.
[0084]
As the polyalkylene ether glycol, those having a weight average molecular weight of 400 to 6000 are used, preferably 500 to 4,000, particularly preferably 600 to 3,000. When the molecular weight is less than 400, the block property of the copolymer is insufficient, and when the weight average molecular weight exceeds 6000, the physical properties of the polymer decrease due to phase separation in the system. Here, as polyalkylene ether glycol, polyethylene glycol, poly (1,2 and 1,3-propylene ether) glycol, polytetramethylene ether glycol, polyhexamethylene ether glycol, block or random copolymer of ethylene oxide and propylene oxide And a block or random copolymer of ethylene oxide and tetrahydrofuran. Particularly preferred is polytetramethylene ether glycol.
[0085]
The content of the polyalkylene ether glycol is desirably 5 to 95% by weight, preferably 10 to 85% by weight, and particularly preferably 20 to 80% by weight with respect to the block copolymer to be formed. When this content is more than 95% by weight, it is difficult to obtain a polymer by condensation polymerization.
[0086]
On the other hand, the polyester polyester block copolymer is a polyester oligomer obtained by condensing an aliphatic or alicyclic dicarboxylic acid and an aliphatic diol in place of the polyalkylene ether glycol having the weight average molecular weight of 400 to 6000. (5) A polyester oligomer synthesized from an aliphatic lactone or an aliphatic monool carboxylic acid, (1) the aliphatic and / or alicyclic diol having 2 to 12 carbon atoms, and (2) an aromatic dicarboxylic acid. Or the alkyl ester is used as a raw material, and the oligomer obtained by esterification reaction or transesterification is polycondensed.
[0087]
Examples of the polyester oligomer (4) include alicyclic dicarboxylic acids such as 1,4-cyclohexanedicarboxylic acid, 1,2-cyclohexanedicarboxylic acid, dicyclohexyl-4,4′-dicarboxylic acid, succinic acid, oxalic acid, Examples include polyester oligomers having a structure in which one or more aliphatic dicarboxylic acids such as adipic acid and sebacic acid are condensed with one or more diols such as ethylene glycol, propylene glycol, tetramethylene glycol, and pentamethylene glycol. Examples of (5) include polycaprolactone polyester oligomers synthesized from ε-caprolactone, ω-oxycaproic acid and the like.
[0088]
Examples of such polyester polyether block copolymers include “Perprene P” (trade name, manufactured by Toyobo Co., Ltd.), “Hytrel” (trade name, manufactured by Toray DuPont), and “Lomod” (Japan EE). "Nichigo Polyester" (trade name, manufactured by Nippon Synthetic Chemical Industry Co., Ltd.), "Teijin Polyester Elastomer" (trade name, manufactured by Teijin Limited), etc., and a polyester polyester block copolymer is a commercially available polymer. There is “Perprene S” (trade name, manufactured by Toyobo Co., Ltd.).
[0089]
(5) Polyamide elastomer
The polyamide-based elastomer has polyamide (nylon 6, 66, 11, 12, etc.) as a hard segment and polyether or polyester as a soft segment. For example, the polyether block amide is represented by the following general formula [I].
[0090]
[Chemical 1]

[0091]
The polyether block amide represented by the above general formula [I] used in the present invention is a known substance per se as disclosed in US Pat. No. 3,044,978.
[0092]
This includes, for example, (i) salts of diamine and dicarboxylic acid, lactams or aminodicarboxylic acids (PA constituent), (b) polyoxyalkylene glycols (PG constituents) such as polyoxyethylene glycol and polyoxypropylene glycol ), And (iii) polycondensation of dicarboxylic acid.
[0093]
Commercially available polyether block amides include "Pebax" (trade name, manufactured by Toray Industries, Inc.), "Daiamide-PAE" (trade name, manufactured by Daicel Huls), and "UBE polyamide elastomer" (manufactured by Ube Industries, Ltd.) Product name), "Novamit PAE" (trade name, manufactured by Mitsubishi Chemical Corporation), "Glais A" (trade name, manufactured by Dainippon Ink & Chemicals, Inc.), "Grillon ELX, ELY" (MS Japan Corporation) Product name).
[0094]
(6) Urethane elastomer
The polyurethane elastomer has a hard segment composed of diisocyanate and short chain glycol (ethylene glycol, propylene glycol, 1,4-butanediol, bisphenol A, etc.) and a soft segment composed of diisocyanate and long chain polyol. . Here, as the long-chain polyol, poly (alkylene oxide) glycol having a molecular weight of 400 to 6,000, for example, polyethylene glycol, poly (1,2 and 1,3-propylene oxide) glycol, poly (tetramethylene oxide) glycol Polyethers such as poly (hexamethylene oxide) glycol, or polyesters such as polyalkylene adipate, polycaprolactone, and polycarbonate are used. This type of polyurethane-based thermoplastic elastomer is a compound having a structure represented by the following general formula [II].
[0095]
[Chemical formula 2]

[0096]
In addition, as this kind of diisocyanate compound, well-known usual things, such as phenylene diisocyanate, tolylene diisocyanate, xylene diisocyanate, 4,4'- diphenylmethane diisocyanate, hexamethylene diisocyanate, can be used.
[0097]
Commercially available polyurethane elastomers include “Elastollan” (trade name, manufactured by Takeda Birdish Urethane Co., Ltd.), “Milactolan” (trade name, manufactured by Nippon Milactolan Co., Ltd.), “Rezamin P” (Daiichi Seikagaku Corporation) ) (Trade name), “Ufine P” (trade name, manufactured by Asahi Glass Co., Ltd.), and the like.
[0098]
The flexural modulus (ASTMD 790) of the thermoplastic elastomer used as the component (C) is desirably 500 or less, and is 1/5 or less of the flexural modulus (ASTM D790) of the thermoplastic resin of the component (A) to be used. More preferably, it has a flexural modulus of 1/8 or less because the effect of improving the conductivity due to the addition of the elastomer is large.
[0099]
  In this invention, the compounding quantity of such (C) component is with respect to a total of 100 weight part of (A) and (B) component.1-30 parts by weight. If the blending amount of the component (C) is less than this, the effect of the invention by blending the component (C) cannot be sufficiently obtained, and if so, as described above, the component (A) and the component (C) The dispersed phase of the component is reversed, and the component (C) becomes the sea phase, and the conductivity is impaired.
[0100]
  (The blending amount of component C) is 0.1 to 10, preferably 0.3 to 5, in weight ratio to component (B).The
[0101]
In addition, when the low Tg component as described in (i) or (ii) above is used for part or all of the component (C), the low Tg component is 100 parts by weight in total of the components (A) and (B). 50 parts by weight or less, preferably 1 to 20 parts by weight. If the blending amount of the low Tg component is less than this, the effect of addition cannot be sufficiently obtained, and if it is more than this, it is not desirable in that the mechanical strength and heat resistance of the resulting molded product are impaired.
[0102]
Furthermore, the content of the low Tg component in the component (C) is preferably 0.5 to 80 parts by weight in 100 parts by weight of the component (C) in terms of uniform conductivity.
[0103]
(D) Additive component
In the conductive thermoplastic resin composition according to the present invention, in addition to the above components (A) to (C), an additional component can be blended as necessary within a range not impairing the above performance.
[0104]
Examples of such additional components include inorganic fibrous reinforcing materials such as glass fiber, silica fiber, silica / alumina fiber, potassium titanate fiber, and aluminum borate fiber, and organic materials such as aramid fiber, polyimide fiber, and fluororesin fiber. Fibrous reinforcement, talc, calcium carbonate, mica, glass beads, glass powder, inorganic fillers such as glass balloons, fluoroplastic powder, solid lubricants such as molybdenum disulfide, plasticizers such as paraffin oil, antioxidants, Heat stabilizer, light stabilizer, UV absorber, neutralizer, lubricant, compatibilizer, anti-fogging agent, anti-blocking agent, slip agent, dispersant, colorant, antibacterial agent, fluorescent brightener, etc. Additives can be mentioned.
[0105]
Furthermore, you may add to the electroconductive thermoplastic resin composition which concerns on this invention as electroconductive fillers other than the fine carbon fiber used by this invention. Examples of such conductive fillers include metal fillers such as aluminum, silver, copper, zinc, nickel, stainless steel, brass, and titanium, graphite (artificial graphite, natural graphite), glassy carbon particles, pitch-based carbon fibers, Examples thereof include conductive fillers such as metal oxide fillers such as PAN-based carbon fibers, titanium oxide, zinc oxide, tin oxide, and indium oxide.
[0106]
Note that, among metal oxide fillers, in the case where surplus electrons are generated due to the presence of lattice defects and show conductivity, a filler added with a dopant to increase conductivity may be used. For example, aluminum is used for zinc oxide, antimony for tin oxide, tin for indium oxide, and the like as dopants. Further, a composite conductive filler in which carbon fiber or the like is coated with metal, or conductive tin oxide or conductive carbon is formed on the surface of potassium titanate whisker or aluminum borate whisker can be used.
[0107]
(E) Manufacturing method
The conductive thermoplastic resin composition according to the present invention can be produced by a normal thermoplastic resin processing method. For example, the components (A), (B) and (C) and all the additional components blended as necessary are mixed in advance, and then a Banbury mixer, roll, brabender, single-screw kneading extruder, twin-screw kneading extrusion It can be produced by melt kneading with a machine, a kneader or the like.
[0108]
Moreover, the semiconductive resin molded article of the present invention can be produced by molding such a conductive thermoplastic resin composition using various melt molding methods. Specific examples of the molding method include compression molding, extrusion molding, vacuum molding, blow molding, and injection molding. Among these molding methods, remarkable effects can be obtained particularly in the injection molding method and the vacuum molding method.
[0109]
In addition, when manufacturing the conductive thermoplastic resin composition according to the present invention, a master batch in which a high concentration of the component (B) is added to a part of the component (A) is manufactured in advance, and then this master batch is used. When the product is diluted with the component (A) and the component (C), the fine carbon fiber of the component (B) is not excessively mixed in the dispersed phase of the component (C), so that the effect of the present invention is enhanced. Alternatively, the total amount of component (B) may be mixed in advance with the total amount of component (A), and then component (C) may be added and mixed.
[0110]
When the semiconductive resin molded product of the present invention is used as an antistatic component for electronic devices, the surface resistance value is 10⁴-10¹⁰Ω, preferably 10⁵-10⁹Control within the range of Ω is preferable in that charging is difficult to occur and the contact current is small.
[0111]
Such control of the surface resistance value includes the viscosity of the component (B), the viscosity ratio of the components (A) and (B), the blending ratio of the components (B) and (C), and molding conditions (resin temperature , Mold temperature, molding pressure, etc.), (B) orientation of fine carbon fibers of component (B) and the degree of relaxation thereof, (C) conductive carbon fragmentation of fine carbon fibers by component dispersed phase and fine carbon fibers The degree of inhibition of the relaxation of the orientation may be controlled.
[0112]
In general, the surface resistance value can be obtained in units of (Ω / □) by converting the resistance value by the shape factor in consideration of the current wraparound in the thickness and width direction of the measurement sample. In the case of a shaped molded article, this conversion is extremely difficult. On the other hand, in practice, the apparent resistance value including the shape is important, and it is not always necessary to use the unit (Ω / □) converted by the shape. Therefore, in this invention, it evaluates with the said surface resistance value ((omega | ohm)).
[0113]
【Example】
Hereinafter, the present invention will be described more specifically with reference to Examples and Comparative Examples.
[0114]
In addition, the compounding raw material used by the Example and the comparative example is as follows.
Polycarbonate resin: “Iupilon S3000” (trade name) manufactured by Mitsubishi Engineering Plastics (Tg = 146 ° C.)
Fine carbon fiber: Type “BN” (trade name) manufactured by Hyperion Catalysis International, Inc. (average fiber diameter = 10 nm, average fiber length = 0.5 μm or more, length / diameter ratio = 50 or more, bending degree = 122 °)
EPR (ethylene propylene copolymer): “EP912P” (trade name) manufactured by Nippon Synthetic Rubber Co., Ltd. (Tg <−50 ° C.)
GMA-PE (ethylene glycidyl methacrylate copolymer): “Bond First E” (trade name) manufactured by Sumitomo Chemical Co., Ltd. (Tg = −23 ° C.)
PP (polypropylene): “NOVATEC MA4U” (trade name) manufactured by Nippon Polychem Co., Ltd. (Tg = 8 ° C.)
PET (polyethylene terephthalate): Unipet “RT553C” (trade name) manufactured by Nippon Unipet Co., Ltd. (Tg = 80 ° C.)
PEI (polyetherimide): “Ultem 1000” manufactured by GE Plastics (Tg = 218 ° C.)
PAR (polyarylate resin): “U polymer U100” (trade name) manufactured by Unitika Ltd. (Tg = 182 ° C.)
[0115]
Examples 1-5, Comparative Examples 1-4
Each component was mixed with the ingredients shown in Table 1, and a barrel temperature of 300 was used using a twin-screw extruder ("PCM45" manufactured by Ikekai Steel Co., Ltd., L / D = 32 (L; screw length, D: screw diameter)). Melting and kneading was performed at ℃ (however, Example 5 and Comparative Example 4 were 350 ℃) and a screw rotation speed of 160 rpm to obtain pellets of a conductive polycarbonate resin composition.
[0116]
In addition, the compounding kneading prepared a master batch in which 15% by weight of fine carbon fiber was previously added to a polycarbonate resin, and diluted this with the remaining components to obtain a predetermined compounding amount.
[0117]
With respect to the obtained conductive thermoplastic resin composition, the surface resistance value of the molded product, the short diameter and aspect ratio of the dispersed phase were measured by the following methods, and the results are shown in Table 1.
[0118]
(1) Surface resistance value
Using each conductive thermoplastic resin composition, a 75 ton injection molding machine with a cylinder temperature of 310 ° C., a mold temperature of 90 ° C. and an injection speed of 15 to 17 cc / sec, a sheet sample for resistance measurement shown in FIG. 10 was molded. About this resistance value measurement sheet sample 10, the surface resistance values of the gate part (film gate side) 10A and the terminal part 10B are measured using a Hiresta UP manufactured by Dia Instruments Co., Ltd. The distance was measured using a distance of 20 mm and a probe diameter of 2 mm. The applied voltage has a resistance value of 1 × 10⁶If it is less than Ω, the voltage is 10V and the resistance value is 1 × 10.⁶If it was Ω or more, the measurement was performed at 100V.
[0119]
(2) Minor diameter and aspect ratio of dispersed phase
With respect to the surface resistance value measuring portions 10A and 10B of the sheet sample 10 for resistance value measurement (1), the minor diameter and the aspect ratio of the dispersed phase of the component (C) were measured.
[0120]
In addition, the injection molded product containing fine carbon fibers has the largest shearing force in the vicinity of the surface, the cooling rate is fast, and as a result, the conductivity becomes low. Therefore, the surface resistance value and practical charging characteristics of the molded product are governed by the dispersed state in the vicinity of the surface. Therefore, in the measurement of the short diameter and aspect ratio of the dispersed phase, the dispersed phase was observed in the range of a depth of 50 μm from the surface.
[0121]
In addition, it is confirmed that the dispersed phase shape of the component (C) is elongated along the flow direction of the resin, so that the flow direction is the largest and the depth direction is the smallest diameter. confirmed. Therefore, the value obtained by measuring the diameter of the dispersed phase in the flow direction was taken as the major axis, and the value measured in the depth direction was taken as the minor axis.
[0122]
As described above, a thin section of a cross section along the flow direction of the resin was cut out from the sample, and after this was dyed, the dispersed phase was observed with a transmission electron microscope, and 30 of the dispersed phases were randomly selected. The diameter and major axis were measured, and the average value was calculated.
[0123]
In addition, in this microscopic observation, it was confirmed that fine carbon fibers were hardly present in the dispersed phase of the component (C).
[0124]
Further, the conductive polycarbonate resin compositions used in Example 1 and Comparative Examples 1 and 2 were examined for conductivity molding temperature dependency by the following method, and the results are shown in Table 2. The relationship between the surface resistance value and the molding temperature is shown in FIG.
[0125]
(3) Molding temperature dependence of conductivity
Using the compositions used in Example 1, Comparative Example 1 and Comparative Example 2, the cooling rate was changed by changing the molding temperature when injection molding the sheet sample 10 for resistance value measurement of (1). Molding was performed (mold temperature: 90 ° C., injection speed: 15 to 17 cc / sec). Next, in the central portion 10C of the obtained sheet sample 10, the surface resistance value and the short diameter of the dispersed phase of the component (C) (only for the example 1) are the above (1), (2) It measured similarly.
[0126]
[Table 1]

[0127]
[Table 2]

[0128]
From Tables 1 and 2 and FIG. 5, the following is clear.
[0129]
That is, if it is the semiconductive resin molded product of the present invention of Examples 1 to 5, the resistance value is 10⁴-10¹⁰In the semiconducting region of Ω, it is possible to obtain a very uniform conductivity distribution, and the dependence on the conductive injection molding temperature is small, and a stable semiconductivity can be obtained under any conditions. .
[0130]
On the other hand, in Comparative Examples 1-3, uniform semiconductivity cannot be obtained.
[0131]
In particular, as can be seen from a comparison between Example 5 and Comparative Example 3, the effect of the present invention is obtained when the minor axis of the dispersed phase of component (C) is outside the scope of the present invention even with the same composition. Cannot be obtained.
[0132]
Further, as in Comparative Example 4, when the component (C) is compatible with the component (A) and, as a result, the component (C) does not form a dispersed phase of 10 μm or more, the variation in conductivity is large. There is no effect.
[0133]
【The invention's effect】
As detailed above, according to the present invention, a resistance value of 10⁴-10¹⁰In the semiconductive region of Ω, a semiconductive resin molded product having uniform conductivity is provided.
[Brief description of the drawings]
FIG. 1A is a schematic cross-sectional view showing a sea-island structure of a semiconductive resin molded article according to an embodiment, and FIG. 1B is a schematic view showing a dispersed phase of component (C). It is sectional drawing.
FIG. 2 is a schematic diagram for explaining a conductive network made of fine carbon fibers.
FIG. 3 is an explanatory diagram of a method for measuring the degree of bending of fine carbon fibers according to the present invention.
FIG. 4 is a plan view showing resistance value measuring sheet samples molded in Examples and Comparative Examples.
FIG. 5 is a graph showing the molding temperature dependence of conductivity in Example 1 and Comparative Examples 1 and 2;
[Explanation of symbols]
1 (A) component (matrix resin)
2 Fine carbon fiber (component (B))
3 (C) component
10 Sheet sample for resistance measurement

Claims (4)

(C) Heat other than the component (A) is added to 100 parts by weight of the conductive resin component consisting of a matrix thermoplastic resin and (B) 0.1 to 20% by weight of fine carbon fibers having an average fiber diameter of 200 nm or less. Conductive thermoplasticity obtained by blending 0.1 to 30 parts by weight of a plastic resin and / or thermoplastic elastomer so that the blending amount of the component (C) is 0.1 to 10 by weight ratio to the component (B) . A semiconductive resin molded product formed by molding a resin composition,
The component (C) is not completely compatible with the component (A), but is dispersed in the shape of a sea island, and the component (C) forms an island-shaped dispersed phase.
The average value of the minor axis of the dispersed phase of the component (C) is 10 μm or less, and the average value of the minor axis of the dispersed phase of the component (C) is the average fiber diameter of the fine carbon fibers of the component (B). 2 times or more and 200 times or less,
The ratio of the minor axis to the major axis (major axis / minor axis) of the dispersed phase of component (C) is 50 or less,
The semiconductive resin molded product characterized in that the fine carbon fiber of the component (B) is substantially not present in the component (C). Oite to claim 1, wherein the component (A) of the thermoplastic resin is a noncrystalline resin, and the (C) at least a portion of the component, wherein (A) a glass transition temperature of the component of the thermoplastic resin ( A semiconductive resin molded article, which is a thermoplastic resin and / or a thermoplastic elastomer having a glass transition temperature (Tg) lower than Tg) by 120 ° C or more. Oite to claim 1, wherein the component (A) of the thermoplastic resin is a crystalline resin, and wherein the (C) at least a portion of the component, wherein (A) the crystalline melting point of the component of the thermoplastic resin (Tm) A semiconductive resin molded article, which is a thermoplastic resin and / or a thermoplastic elastomer having a glass transition temperature (Tg) lower by 200 ° C. or more. 3. The semiconductive resin molded article according to claim 1, wherein the component (A) is a polycarbonate resin.

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