JP2005015609A - Semiconductive resin composition, method of producing the same, semiconductive sheet and charge control member - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a semiconductive resin composition which has a volume resistivity in the semiconductive region, has a small variation in the volume resistivity by location, has good mechanical properties such as tensile modulus and elongation at break, heat resistance, flame retardancy and moldability, and can be colored into any desired colors including white. <P>SOLUTION: The semiconductive resin composition contains 50-98.9 mass% of a polyvinylidene fluoride resin, 0.5-20 mass% of an amorphous polyester resin, 0.5-20 mass% of a pigment, and 0.1-10 mass% of an ion conductive agent. This resin composition is used to make a semiconductive sheet and a charge control member. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

【００３０】
（式中、Ｒ^１〜Ｒ^４は、互いに同一または相異なるアルキル基であり、Ｒ^５は、アルキル基、フルオロアルキル基または水素原子である。）
で表される化合物である。
【００３１】
テトラアルキルアンモニウム亜硫酸塩は、下記式（２）
【００３２】
【化４】

【００３３】
（式中、Ｒ^６〜Ｒ^９は、互いに同一または相異なるアルキル基であり、Ｒ^１０は、アルキル基、フルオロアルキル基または水素原子である。）
で表される化合物である。
【００３４】
式（１）及び（２）で表される各化合物において、アルキル基の炭素原子数の合計は、好ましくは８〜３０、より好ましくは１２〜２４、特に好ましくは１５〜２０である。アルキル基としては、メチル基、エチル基、プロピル基、イソプロピル基、ｎ−ブチル基、ｔ−ブチル基、ペンチル基、ヘキシル基などの炭素数１〜６の短鎖アルキル基が好ましい。フルオロアルキル基としては、ＣＦ_３、Ｃ_２Ｆ_５などの短鎖フルオロアルキル基が好ましい。
【００３５】
式（１）及び（２）で表される各化合物の具体例としては、（Ｃ_２Ｈ_５）_４Ｎ^＋、（Ｃ_３Ｈ_７）_４Ｎ^＋、（Ｃ_４Ｈ_９）_４Ｎ^＋、（Ｃ_５Ｈ_１１）_４Ｎ^＋などの四級アンモニウムカチオンと、ＣＦ_３ＳＯ_４ ⁻、ＣＨ_３ＳＯ_４ ⁻、ＨＳＯ_４ ⁻、ＣＦ_３ＳＯ_３ー、ＣＨ_３ＳＯ_３ ⁻、ＨＳＯ_３−などの硫酸または亜硫酸を含むアニオンとからなる塩を挙げることができる。これらの化合物は、２種類以上のアニオン及び／またはカチオンを組み合わせた塩であってもよい。また、四級アンモニウムが有する４つのアルキル基は、それぞれが同一であっても異なっていてもよい。これらの中でも、テトラアルキルアンモニウムの硫酸水素塩が好ましく、テトラブチルアンモニウム硫酸水素塩が特に好ましい。
【００３６】
３．非晶性ポリエステル樹脂：
本発明で使用する非晶性ポリエステル樹脂は、示差走査熱量計（ＤＳＣ）による熱分析で１００〜３００℃の範囲内に１０Ｊ／ｇ以上の結晶融解熱（ΔＨ）を有するピークが検知されない本質的に非結晶性のポリエステル樹脂であることが好ましい。この結晶融解熱（ΔＨ）は、好ましくは５Ｊ／ｇ以下、より好ましく３Ｊ／ｇ以下、最も好ましくは実質的にゼロＪ／ｇである。このように、本発明で使用する非晶性ポリエステル樹脂は、本質的に非結晶性であって、如何なる成形条件によっても結晶化しないものであることが望ましい。
【００３７】
非晶性ポリエステル樹脂は、ポリエチレンテレフタレート（ＰＥＴ）やポリブチレンテレフタレート（ＰＢＴ）などの熱可塑性ポリエステル樹脂のジカルボン酸成分及び／またはジオール成分の一部を他の共重合成分で置き換えて、結晶性を低下または消失させたコポリエステルである。共重合成分の割合は、通常２０〜５０モル％、好ましくは２５〜４０モル％、より好ましくは３０〜３５モル％である。共重合成分の割合が低すぎると、ポリエステル樹脂に結晶性が現われたり、結晶性の程度が高くなり、半導電性シートなどの成形物の引張破断伸びや柔軟性が低下する。
【００３８】
非晶性ポリエステル樹脂は、ジカルボン酸成分とジオール成分との等モルの重縮合物である。各成分の共重合割合は、ジカルボン酸成分とジオール成分の合計２００モル％を基準として算出する。例えば、ＰＥＴ樹脂を構成するジオール成分のエチレングリコール（ＥＧ）の一部を１，４−シクロヘキサンジメタノール（ＣＨＤＭ）に置き換えて、ＥＧ７０モル％とＣＨＤＭ３０モル％からなるジオール成分（合計１００モル％）とした場合、共重合体中のテレフタル酸とＥＧから形成される繰り返し単位の割合が７０モル％となり、テレフタル酸とＣＨＤＭとから形成される繰り返し単位の割合が３０モル％となる。この場合、共重合成分であるＣＨＤＭの割合を３０モル％という。
【００３９】
共重合成分としては、プロピレングリコール、１，４−ブタンジオール、キシリレングリコール、ビスフェノールＡ、ジエチレングリコール、１，４−シクロヘキサジメタノールなどのジオール成分；イソフタル酸、セバシン酸、アジピン酸などのジカルボン酸成分；などが挙げられる。これらの非晶性ポリエステル樹脂は、それぞれ単独で、あるいは２種類以上を組み合わせて使用することができる。
【００４０】
本発明で使用する非晶性ポリエステル樹脂の中でも、ジカルボン酸成分がテレフタル酸を主体とするものであり、かつ、グリコール成分がエチレングリコール（ＥＧ）と１，４−シクロヘキサンジメタノール（ＣＨＤＭ）を主体とするコポリエステルが好ましい。より具体的に、本発明で使用する非晶性ポリエステル樹脂としては、１，４−シクロヘキサンジメタノールを共重合成分とする非晶性ポリエチレンテレフタレート共重合体（ＰＥＴＧ）であることが好ましい。ＰＥＴＧは、ＰＥＴ樹脂を構成するグリコール成分であるエチレングリコール（ＥＧ）の一部を１，４−シクロヘキサンジメタノール（ＣＨＤＭ）に置き換えたコポリエステルである。ＥＧの一部をＣＨＤＭに置き換えて共重合させると、ＣＨＤＭの共重合割合がある範囲内で結晶化度が実質的にゼロのコポリエステル（即ち、ＰＥＴＧ）が得られる。
【００４１】
非結晶性のＰＥＴＧにおいて、グリコール成分中のＣＨＤＭの割合は、ＥＧよりも少なく、好ましくは２５〜４０モル％、より好ましくは３０〜３５モル％程度である。これに対応して、ＥＧの割合は、好ましくは６０〜７５モル％、より好ましくは６５〜７０モル％となる。ＰＥＴＧは、イーストマンケミカル社からＥＡＳＴＡＲ ＰＥＴＧ６７６３（ＣＨＤＭ＝３１±３モル％）の商品名で市販されているものがあり、本発明では、この市販品を好適に用いることができる。もちろん、前記で定義した「ＤＳＣによる熱分析で１８０〜３００℃の範囲内に１０Ｊ／ｇ以上の結晶融解熱（ΔＨ）を有するピークが検知されない本質的に非結晶性のポリエステル樹脂」であれば、その他のグレードの市販品や合成品も使用することができる。
【００４２】
４．顔料：
本発明で使用する顔料は、特に制限されず、各種の有機顔料及び無機顔料を挙げることができるが、樹脂成分と溶融混錬する際の温度で分解しないだけの耐熱性を有することが必要である。本発明で使用する有機顔料としては、例えば、不溶性アゾ顔料、縮合アゾ顔料等のアゾ系顔料；アントラキノン系顔料、ペリノン系顔料、ペリレン系顔料、チオインジゴ系顔料等のスレン系顔料；フタロシアニンブルー、フタロシアニングリーン等のフタロシアニン系顔料；ナフトールグリーンＢ、ナフトールグリーンＹ等のニトロソ顔料；キナクリドン系顔料、ジオキサジン系顔料、イソインドリノン系顔料、ピロロピロール系顔料、アニリンブラック、有機蛍光顔料等の各種顔料が挙げられる。
【００４３】
本発明で使用する無機顔料としては、例えば、クレー、バライト、雲母、黄土等の天然物；黄鉛、亜鉛黄、バリウム黄等のクロム酸塩；紺青等のフェロシアン化物；硫化亜鉛等の硫化物；硫酸バリウム等の硫酸塩；酸化クロム、酸化亜鉛（亜鉛華）、酸化チタン（チタンホワイト）、弁柄、鉄黒、酸化クロム等の酸化物；水酸化アルミニウム等の水酸化物；ケイ酸カルシウム、群青等のケイ酸塩；炭酸カルシウム、炭酸マグネシウム等の炭酸塩；カーボンブラック、松煙、ボーンブラック、グラファイト等の炭素；アルミニウム粉、ブロンズ粉、亜鉛末等の金属粉；焼成顔料等が挙げられる。
【００４４】
顔料は、それぞれ単独で、あるいは２種以上を組み合わせて使用することができる。本発明の半導電性樹脂組成物を白色化する場合には、白色顔料として酸化チタン（チタンホワイト；ＴｉＯ_２）が好適に使用される。酸化チタンは、ルチル型結晶形を有するものであることが好ましい。酸化チタンは、白色度及び屈折率が高いことに加えて、一般に粒子径が０．１５〜０．３μｍと小さく、不透明性の高い半導電性樹脂組成物を形成することができる。
【００４５】
５．半導電性樹脂組成物：
本発明の樹脂組成物は、（Ａ）ポリフッ化ビニリデン系樹脂５０〜９８．４質量％、（Ｂ）非晶性ポリエステル１〜２０質量％、（Ｃ）顔料０．５〜２０質量％、及び（Ｄ）イオン性導電剤０．１〜１０質量％を含有する半導電性樹脂組成物である。
【００４６】
ポリフッ化ビニリデン系樹脂の配合割合は、５０〜９８．９質量％、好ましくは６２〜９７．９質量％、より好ましくは７３〜９７質量％、特に好ましくは８２〜９６質量％の範囲内である。ポリフッ化ビニリデン系樹脂の配合割合が小さすぎると、機械的物性、耐熱性、難燃性などの優れた特性が低下する。ポリフッ化ビニリデン系樹脂の配合割合が大きすぎると、着色性及び導電性が不充分になる。
【００４７】
非晶性ポリエステル樹脂の配合割合は、０．５〜２０質量％、好ましくは０．８〜１５質量％、より好ましくは１〜１０質量％、特に好ましくは１〜６質量％の範囲内である。非晶性ポリエステル樹脂の配合割合が小さすぎると、顔料がイオン性導電剤と化学反応を起こし易くなる。非晶性ポリエステル樹脂の配合割合が大きすぎると、各成分の分散性が不良になり易い。特に、非晶性ポリエステル樹脂の配合割合が大きすぎる半導電性樹脂組成物をシートに押出成形すると、該シートの幅方向（ＴＤ）の引張破断伸びが著しく低下して、流れ方向に裂け易くなる（すなわち、シートが縦裂きする）。
【００４８】
顔料の配合割合は、０．５〜２０質量％、好ましくは０．８〜１５質量％、より好ましくは１〜１０質量％、特に好ましくは１〜６質量％の範囲内である。顔料の配合割合が小さすぎると、着色の程度が不充分となり易く、白色顔料を用いた場合には、樹脂組成物の白色度が低くなり易い。顔料の配合割合が大きすぎると、樹脂組成物が脆くなり易い。
【００４９】
イオン性導電剤の配合割合は、０．１〜１０質量％、好ましくは０．５〜８質量％、より好ましくは１〜７質量％、特に好ましくは２〜６質量％の範囲内である。イオン性導電剤の配合割合が小さすぎると、半導電性領域の体積抵抗率を有する樹脂組成物を得ることが困難になる。イオン性導電剤の配合割合が大きすぎると、イオン性導電剤が分散不良となり易く、樹脂組成物の機械的物性が低下したり、耐熱性が悪くなる。
【００５０】
（Ｂ）非晶性ポリエステル樹脂と（Ｃ）顔料の配合比（質量比）は、通常１：２０〜４０：１、好ましくは２：８〜８：２、より好ましくは３：７〜７：３、特に好ましくは４：６〜６：４の範囲内である。非晶性ポリエステル樹脂の配合比率が大きすぎると、着色の程度が不充分になり易く、白色顔料の場合には、充分な白色度を得ることが困難になる。非晶性ポリエステル樹脂の配合比率が小さすぎると、顔料がイオン性導電剤と化学反応を起こし易くなる。
【００５１】
本発明の半導電性樹脂組成物は、体積抵抗率（平均値）が通常１．０×１０^３〜１．０×１０^１３Ωｃｍ、好ましくは１．０×１０^５〜１．０×１０^１２Ωｃｍ、より好ましくは１．０×１０^６〜１．５×１０^１１Ωｃｍの範囲内であり、これらの範囲内の体積抵抗率を示す半導電性シート及び各種成形物を与えることができる。
【００５２】
本発明の半導電性樹脂組成物には、所望により、本発明の目的を損なわない範囲内で、酸化防止剤、滑剤、可塑剤、紫外線吸収剤、ｐＨ調整剤、カップリング剤、顔料以外の充填剤などを適宜添加することができる。
【００５３】
６．半導電性樹脂組成物の製造方法、成形方法、及び成形物
本発明の半導電性樹脂組成物は、前記各成分を溶融混練することにより製造することができる。顔料とイオン性導電剤との間の反応性が高い場合には、非晶性ポリエステル樹脂及び顔料を、一軸押出機、二軸押出機、バンバリーミキサー、ロールミル、ニーダー等の混錬機を用いて溶融混錬して、マスターバッチ（混合物）を調製しておくことが好ましい。他方、ポリフッ化ビニリデン系樹脂及びイオン性導電剤も予め前記の混錬機で溶融混練して混合物としておくことが好ましい。後者の混合物は、ポリフッ化ビニリデン系樹脂に高濃度のイオン性導電剤を溶融混練したマスターバッチであってもよい、これらのマスターバッチや混合物は、通常、ペレット化しておくことが好ましい。
【００５４】
したがって、半導電性樹脂組成物の好ましい製造方法は、（Ａ）ポリフッ化ビニリデン系樹脂及び（Ｄ）イオン性導電剤を含有する混合物と、（Ｂ）非晶性ポリエステル樹脂及び（Ｃ）顔料を含有する混合物（マスターバッチ）とを溶融混練する工程を含む製造方法である。これらの混合物を溶融混練するに際し、必要に応じて、ポリフッ化ビニリデン系樹脂及び／または非晶性ポリエステル樹脂をブレンドして、各成分の割合が所望の範囲内となるように調整することができる。
【００５５】
非晶性ポリエステル樹脂は、ポリフッ化ビニリデン系樹脂と比較して表面エネルギーが大きいため、顔料の表面を濡らし易い。他方、ポリフッ化ビニリデン系樹脂は、非晶性ポリエステル樹脂と比較して極性が高いため、イオン性導電剤を溶媒和し易い。このため、本発明の半導電性樹脂組成物においては、顔料とイオン性導電剤とが直接的に反応する確率が低くなると考えられる。
【００５６】
特に（Ａ）ポリフッ化ビニリデン系樹脂及び（Ｄ）イオン性導電剤を含有する混合物と、（Ｂ）非晶性ポリエステル樹脂及び（Ｃ）顔料を含有する混合物とを溶融混練し、その際、必要に応じて、ポリフッ化ビニリデン系樹脂または非結晶性ポリエステル樹脂若しくはこれら両者を加えて溶融混練する工程を含む製造方法を採用すると、（Ａ）ポリフッ化ビニリデン系樹脂がマトリックスを形成し、該マトリックス中に、（Ｃ）顔料を含有する（Ｂ）非晶性ポリエステル樹脂と、（Ｄ）イオン性導電剤とが、それぞれ分散した半導電性樹脂組成物を得ることができ、それによって、顔料とイオン性導電剤とが接触して直接的に反応する確率をより一層低くすることができると考えられる。
【００５７】
本発明の半導電性樹脂組成物の成形方法は、特に制限されるものではなく、射出成形や溶融押出法などの一般的な溶融成形法により、例えば、シート、ファイバー、その他の成形品に成形することができる。成形後、さらに成形物を延伸や熱固定することも可能である。本発明の半導電性樹脂組成物は、それ単独で使用してもよく、また、必要に応じて他の樹脂層などと複合化させて、積層シートや複合糸などにしてもよい。
【００５８】
半導電性樹脂組成物を用いて半導電性シートを成形する方法としては、一軸または二軸スクリュー押出機とＴダイを用いて、連続的にシート状に溶融押出成形する方法を採用することが好ましい。
【００５９】
半導電性シートの成形は、押出機の先端に取り付けたＴダイから溶融状態の該樹脂組成物をＴダイのリップの直下に押し出し、冷却ドラム上にエアーナイフなどにより密着させつつ冷却固化する方法を採用することが好ましい。半導電性シートは、通常、Ｔダイからシート状に成形されるが、環状ダイを用いて半導電性シートを直接シームレスベルトまたはチューブなどの形状に成形することもできる。シームレスベルトまたはチューブの望ましい連続的な溶融押出成形法としては、一軸スクリュー押出機とスパイラル環状ダイを用い、溶融樹脂組成物を該環状ダイのリップから直下に環状に押し出し、内部冷却マンドレル方式によって環状体の内径を制御しながら引き取る方法が挙げられる。
【００６０】
本発明の半導電性樹脂組成物は、成形時に直接シームレスベルトやチューブに成形することができるが、それ以外の通常のシート状に成形した場合には、得られた半導電性シートを二次加工することにより、各種の電荷制御部材に形成することができる。その一つの方法は、半導電性シートの加熱シームによるエンドレスベルトやチューブの成形である。本発明の半導電性シートを加熱シームで接着してベルト状に成形する場合などは、シートの加熱個所（再溶融個所）は、一部分でもシート全体でもよい。
【００６１】
本発明の半導電性シートは、他の素材から形成されたベルト状基体（例えば、ポリイミドフィルムからなるベルト）上に被覆することにより、積層ベルトに形成することができる。また、本発明の半導電性シートは、他の導電性シートや半導電性シート、あるいは絶縁シートなどと２層以上に積層してもよい。積層するには、各層の界面を接着剤で張り合わせても、共押出により多層シートとして成形してもよい。さらに、本発明の半導電性シートは、ローラ状基体（例えば、芯金）上に被覆することにより、被覆ローラを形成することができる。半導電性樹脂組成物から形成されたチューブをローラ状基体上に被覆することもできる。
【００６２】
本発明の半導電性シートや電荷制御部材の表面は、用途に応じて、他の樹脂をコーティングしたり、金属蒸着したり、艶消し加工してもよい。ただし、白色等の所望の色調をそのまま利用する場合には、表面加工することなく使用することが好ましい。特に、本発明の半導電性シートを壁紙、ＯＡ機器外装材、間仕切りなどとして使用する場合には、色調を発揮する上で、表面加工することなく使用することが好ましい。
【００６３】
本発明の半導電性シートの厚みは、用途に応じて適宜定めることができるが、通常２０〜１０００μｍ、好ましくは３０〜５００μｍ、より好ましくは４０〜２５０μｍ、特に好ましくは５０〜２００μｍである。半導電性シートの厚みが薄すぎると強度が低下し、厚すぎると柔軟性が低下する。
【００６４】
本発明の半導電性シートの体積抵抗率（平均値）は、１．０×１０^３〜１．０×１０^１３Ωｃｍ、好ましくは１．０×１０^５〜１．０×１０^１２Ωｃｍ、より好ましくは１．０×１０^６〜１．５×１０^１１Ωｃｍの範囲内に調整され、用途に応じて、この範囲内から所望の体積抵抗率となるように、各成分の種類と配合割合を調節する。本発明の電荷制御部材の殆んどは、半導電性シートを二次加工することにより製造することができる。また、壁紙やＯＡ機器外装材などは、半導電性シートをそのままの形状で使用する。
【００６５】
そこで、例えば、半導電性シートを現像ローラの被覆チューブ、感光体ベルト若しくはローラの被覆チューブ、除電ベルト若しくはローラの被覆チューブまたは除電ブレードとして使用する場合には、その体積抵抗率を好ましくは１．０×１０^５〜１．０×１０^９Ωｃｍ、より好ましくは１．０×１０^６〜１．０×１０^８Ωｃｍの範囲内に調節する。半導電性シートを紙搬送ベルトとして使用する場合には、その体積抵抗率を好ましくは１．０×１０^５〜１．０×１０^１３Ωｃｍ、より好ましくは１．０×１０^８〜１．０×１０^１２Ωｃｍの範囲内に調節する。半導電性シートを転写ベルト若しくはロールの被覆チューブ、帯電ベルト若しくはロールの被覆チューブまたは帯電ブレードとして使用する場合には、その体積抵抗率を好ましくは１．０×１０^５〜１．０×１０^１３Ωｃｍ、より好ましくは１．０×１０^７〜１０^１１Ωｃｍの範囲内に調節する。
【００６６】
半導電性シートは、場所による体積抵抗率のバラツキができるだけ小さいものであることが均一な電荷制御機能を発揮する上で望ましい。半導電性シートが電荷制御部材として満足に機能するには、体積抵抗率の最大値が最小値の３０倍以内にあることが必要とされるが、本発明によれば、表面積１ｍ^２当たり任意に選んだ２０点で測定した体積抵抗率の最大値が最小値の通常１０倍以下、好ましくは１〜６倍、より好ましくは１〜４倍、特に好ましくは１〜３倍の範囲内の半導電性シートを得ることができる。このような半導電性シートの体積抵抗率に関する特性は、本発明の半導電性樹脂組成物を用いて形成された電荷制御部材の特性と一致する。
【００６７】
電荷制御部材が例えば転写ベルトである場合、該ベルトが歪むと、ベルト上に形成されるトナー画像の歪みや色ずれの原因になる。そのため、半導電性シートは、十分に高い弾性率を有することが望ましい、また、ベルト部材は、異物の巻き込み等によって割れたりすることが無いように、適度な柔軟性を有することが望ましい。本発明の半導電性シートは、引張弾性率と引張破断伸びが共に優れており、上記要求に応えることができるものである。
【００６８】
具体的に、本発明の半導電性シートは、引張弾性率が好ましくは０．７ＧＰａ以上、より好ましくは０．９ＧＰａ以上、特に好ましくは１．０ＧＰａ以上であり、多くの場合１．２ＧＰａ以上とすることができる。引張弾性率の上限値は、通常４．０ＧＰａ、多くの場合２．０ＧＰａ程度である。
【００６９】
本発明の半導電性シートの引張破断伸びは、押出成形時の押出方向（ＭＤ）では、一般に、実質的に測定限界である２００％を超える高い値を示す。半導電性シートの横方向（ＴＤ）の引張破断伸びは、非晶性ポリエステル樹脂やイオン性導電剤、顔料の配合割合によって変動することが多いが、好ましくは５％以上、より好ましくは１０％以上、特に好ましくは２０％以上である。非晶性ポリエステル樹脂やイオン性導電剤、顔料の配合割合を選択することにより、横方向（ＴＤ）の引張破断伸びを３０％以上、さらには４０％以上とすることができる。
【００７０】
本発明の半導電性シートまたはベルトの平行光線透過率は、通常３０％以下、好ましくは１５％以下、より好ましくは１０％以下、特に好ましくは５％以下である。
【００７１】
本発明の半導電性樹脂組成物を中間転写材ベルトや、紙搬送ベルトなどの電荷制御部材として使用する場合には、色調は白色を基調とすることが好ましく、白色を基調とした無彩色が特に好ましく、白色が最も好ましい。本発明の半導電性樹脂組成物の白色度（Ｗ）は、通常６０％以上、好ましくは６５％以上、より好ましくは７０％以上である。白色度は、必要に応じて７５％以上、さらには８０％以上とすることもできる。本発明の半導電性樹脂組成物の黄色度（ＹＩ）は、通常−２０〜２０％、好ましくは−１５〜１５％、より好ましくは−１０〜１０％の範囲である。
【００７２】
本発明の半導電性シートや電荷制御部材は、使用する顔料に応じて種々の色調に着色されている。本発明の半導電性樹脂組成物は、ポリフッ化ビニリデン系樹脂を主成分としているので、該樹脂組成物から形成された半導電性シートや電荷制御部材は、耐熱性及び難燃性に優れている。
【００７３】
【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。物性の測定方法は、以下の通りである。
（１）厚み測定：
成形物の厚みは、ダイヤルゲージ厚み計（小野測器社製、商品名：ＤＧ−９１１）を用いて測定した。
【００７４】
（２）体積抵抗率：
リング状プローブ（三菱化学社製、商品名ＵＲＳプローブ；内側電極の外径５．９ｍｍ、外側電極の内径１１．０ｍｍ、外側電極の外径１７．８ｍｍ）と測定ステージ（三菱化学社製、商品名レジテーブルＵＦＬ）との間に試料を挟み、約３ｋｇ重の圧力で押さえつけつつ、プローブの内側の電極と測定ステージとの間に１００Ｖの電圧を印加し、抵抗率測定装置（三菱化学社製、商品名ハイレスタＵＰ）で体積抵抗率を求めた。リング電極法による体積抵抗率測定法の詳細は、ＪＩＳ−Ｋ６９１１に記載されている。
【００７５】
（３）平均値の算出：
上記した厚み及び体積抵抗率の測定は、これらの値を測定すべき試料の表面積１ｍ^２当たり任意に選んだ２０点の測定点について測定し、その最大値、最小値及び平均値（算術平均）を求めた。
【００７６】
（４）引張弾性率及び引張破断伸び：
ＪＩＳ Ｋ−７１１３に準拠し、幅１０ｍｍ、長さ１００ｍｍの短冊型試験片を作製して、引張試験機（オリエンテック社製、商品名テンシロンＲＴＭ１００型）により引張速度５０ｍｍ／分、チャック間距離５０ｍｍの条件で測定した。
【００７７】
（５）平行光線透過率：
平行光線透過率は、へイズメータ（日本電色工業社製、商品名Σ８０）を用いて「曇価」として測定した。測定方法の詳細は、ＪＩＳ Ｋ−７１０５に記載されている。
【００７８】
（６）示差走査熱量計（ＤＳＣ）による熱分析：
示差走査熱量測定装置（メトラー社製、製品名ＤＳＣ３０）とデータプロセッサ（メトラー社製、製品名ＴＣ１０Ａ）とを用い、試料（ペレット）を下記条件により熱分析した。試料は、７５℃で１０時間コンディショニングした後、測定に供した。ファーストランにより、結晶融解ピーク温度と結晶融解熱（ΔＨ）を求めた。測定条件は、試料重量１０ｍｇ、測定開始温度３０℃、測定終了温度３００℃、昇温速度１０℃／分である。
【００７９】
（７）白色度及び黄色度：
白色度（Ｗ）と黄色度（ＹＩ）は、カラーメーター（日本電色工業社製、商品名ＺＥ２０００）を用いて測定した。白色度と黄色度の詳細は、ＪＩＳ Ｐ−８７１５、及びＪＩＳ Ｚ−８７１５に記載されている。
【００８０】
［実施例１〜４、比較例１〜６］
表１に示す組成の原料を一軸スクリュー押出機に供給して、リップクリアランス０．７ｍｍのＴダイからシート状に溶融押出し、直ちに８０℃の冷却ロールによって冷却して、厚みが約５０μｍのシート（フイルム）に成形した。ただし、イオン性導電剤は、ＰＶＤＦに所定量のイオン性導電剤を添加したペレットを予め作製しておき、製膜時に他の成分とブレンドした。実施例１〜４では、予め非晶性ポリエステル樹脂に顔料を５０質量％の濃度で配合したマスターバッチペレットを作製しておき、製膜時に他の成分とブレンドした。結果を表１及び表２に示す。実施例１〜４の半導電性樹脂組成物は、白色だった。比較例２の割合処方の場合には、樹脂成分が分解、発泡してシートに成形することができなかった。
【００８１】
【表１】

【００８２】
（脚注）
（１）ＰＶＤＦ：ポリフッ化ビニリデン樹脂（呉羽化学工業製、ＫＦ＃１０００）
（２）ＴＢＡＨＳ：テトラブチルアンモニウム硫酸水素塩〔（Ｃ_４Ｈ_９）_４ＮＨＳＯ_４；広栄化学製〕
（３）ＰＥＴＧ：非晶性ポリエステル樹脂（イーストマンケミカル製、ＥＡＳＴＥＲ６７６３；１００〜３００℃の間にＤＳＣ結晶融解ピーク温度なし）
（４）ＴｉＯ_２：酸化チタン粉末（デュポン社製、Ｒ１０１）
【００８３】
【表２】

【００８４】
【発明の効果】
本発明によれば、半導電性領域の任意の体積抵抗率を有し、かつ所望の色調に着色可能な成形物を成形することができる半導電性樹脂組成物、その製造方法、該樹脂組成物を溶融成形してなる半導電性シート、及び該樹脂組成物から形成された電荷制御部材が提供される。本発明の半導電性樹脂組成物は、電子写真方式やインクジェット方式の画像形成装置における各種電荷制御部材、塵埃吸着防止性の壁紙やＯＡ機器外装材などの樹脂材料として好適である。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a semiconductive resin composition capable of forming a molded product having an arbitrary volume resistivity of a semiconductive region and capable of being colored in a desired color tone, a method for producing the same, and the resin composition. The present invention relates to a semiconductive sheet formed by melt molding and a charge control member formed from the resin composition. The semiconductive resin composition of the present invention is suitable as a resin material for various members, dust adsorption-preventing wallpaper, OA equipment exterior materials, and the like in electrophotographic and inkjet image forming apparatuses.
[0002]
In the present invention, the semiconductive resin composition is 10³-10¹³It means a resin composition having a volume resistivity in the range of Ωcm. The semiconductive sheet of the present invention includes not only a typical sheet having a thickness of 250 μm or more but also a film having a thickness of less than 250 μm.
[0003]
[Prior art]
Synthetic resin moldings having a volume resistivity in the semiconductive region are used in various fields as charge control members. Representative fields include image forming apparatuses such as electrophotographic (including electrostatic recording) copying machines, laser beam printers, and facsimiles.
[0004]
For example, in an electrophotographic copying machine, (1) a charging step for uniformly and uniformly charging the surface of the photoconductor, and (2) exposure for forming an electrostatic latent image on the surface of the photoconductor by exposing it to a pattern. (3) a developing step in which a developer (toner) is attached to the electrostatic latent image on the surface of the photosensitive member to form a visible image (toner image); (4) the toner image on the surface of the photosensitive member is transferred to a transfer material (transfer paper (5) a fixing process for fusing the toner image on the transfer material, (6) a cleaning process for cleaning residual toner on the surface of the photoreceptor, and (7) a cleaning process for transferring the toner image on the surface of the photoreceptor. An image is formed by each process such as a charge removal process for eliminating residual charges.
[0005]
In such an image forming apparatus, a large number of members having various shapes such as a belt, a roller, a drum, and a blade are disposed in order to perform functions in the respective steps. Examples of such a member include a charging member (for example, a charging belt and a charging roller), a photosensitive drum (for example, a photosensitive layer and a belt-shaped or roller-shaped support for supporting the photosensitive layer), and a developing member (for example, Developing roller, developing belt), developer layer thickness regulating member (for example, toner layer thickness regulating blade), transfer member (for example, transfer belt, intermediate transfer belt, transfer roller), cleaning member (for example, cleaning blade), static elimination Examples thereof include a member (for example, a static elimination blade, a static elimination belt, a static elimination roller), a paper conveyance member, and the like. The belt member usually has an endless belt or tube shape. The roller member is a coated roller having a resin or rubber coating layer on a roller-shaped substrate.
[0006]
In each of the steps, since it is necessary to strictly control static electricity or electric charge, many of the members used in each step are required to have appropriate conductivity. For example, in a charging method using a charging belt, a charging belt to which a voltage is applied is brought into contact with the surface of the photoconductor to charge the surface of the photoconductor directly from the charging belt. In the development method using a non-magnetic one-component developer, a developing roller is disposed opposite the photoconductor, and the toner is attached to the surface of the developing roller in a charged state by the frictional force between the developing roller and the toner supply roller. After this is made uniform with a toner layer thickness regulating blade, the electrostatic latent image on the surface of the photoreceptor is shifted by an electric attractive force. In the transfer method using an endless belt, a transfer material is conveyed by an endless belt, and a transfer electric field is formed by applying a charge opposite to the toner to the belt, and a toner image on the surface of the photoconductor is transferred by Coulomb force. It is transferred onto the material.
[0007]
Many of these various members exhibit their respective functions so that the entire member or at least the surface layer has appropriate conductivity, more specifically, 10 belonging to the semiconductive region.³-10¹³It is required to have a volume resistivity in the range of Ωcm. Since these members can exhibit a charge control function by being semiconductive, it can be said that they are charge control members. In recent years, as such charge control members, those formed of a synthetic resin material imparted with appropriate conductivity have been widely used.
[0008]
Even in an ink jet printer, various processes such as paper adsorption, transport, separation, and cleaning of deposits are performed by controlling the charge on a paper transport member (for example, a belt). A member is used. Synthetic resin wallpaper and OA equipment exterior materials are also desired to have semiconductivity in order to prevent dust adsorption.
[0009]
The charge control member is required to have a volume resistivity of a semiconductive region, but it is desirable that the volume resistivity is substantially uniform with little variation depending on the location of the member. For example, if a charging belt with large variations in volume resistivity is used, the surface of the photoreceptor cannot be uniformly charged. If a transfer belt having a large variation in volume resistivity is used, the toner image on the surface of the photoreceptor cannot be accurately transferred onto the transfer material. As a result, a high quality image cannot be obtained.
[0010]
In addition, the charge control member is required to have a high degree of durability. When the charge control member is an endless belt, it is driven for a long time using two or more rolls, and when it is a roller member, it is rotated at a high speed. For this reason, the charge control member is required to have sufficient durability to withstand such severe operating conditions. As mechanical properties, it is particularly desirable that both the tensile modulus and the tensile elongation at break are excellent. For example, if the tensile modulus of the belt is too low, the belt will be distorted and the durability will not be lost. In the case of an intermediate transfer belt, the toner image transferred on the belt may be distorted or misaligned. Cause. When the tensile / tensile elongation at break of the charge control member is too low, the flexibility is insufficient and cracking due to inclusion of foreign matter or the like is likely to occur.
[0011]
The charge control member is often used in a high temperature atmosphere, and the charge control member mounted on the electrophotographic copying machine may be applied with a high voltage of 100 V to several kV or more. , Exposed to danger of sparks and sparks from heating. For this reason, the charge control member is required to have excellent heat resistance and flame retardancy.
[0012]
Furthermore, in addition to the above characteristics, the charge control member is required to be able to be colored in an arbitrary color tone. For example, when the charge control member is a dust adsorption preventing wallpaper, an OA equipment exterior material, or the like, it is necessary to color the tone according to the user's request. In a paper conveyance belt or transfer belt in a full-color image forming apparatus or the like, the color tone of the belt is preferably white in order to check the color tone of the color toner or color ink on the belt or the transfer paper or OHP sheet. .
[0013]
However, when general-purpose conductive carbon black is blended as a conductive filler in order to impart semiconductivity to the synthetic resin, the resulting resin composition becomes black, and a semi-color having a desired color tone other than black as well as white. A conductive composition cannot be obtained. Moreover, the semiconductive resin composition melt-molded using a resin composition containing conductive carbon black has a large variation in conductivity depending on the location.
[0014]
Conventionally, as a semiconductive resin composition with small variations in volume resistivity depending on the location and small changes in volume resistivity and surface resistivity due to changes in environmental humidity, polyvinylidene fluoride resin and alkyl quaternary ammonium sulfate or sulfite A polyvinylidene fluoride resin composition to which a salt is added has been proposed (for example, see Patent Document 1). This polyvinylidene fluoride resin composition is excellent in transparency because it imparts semiconductivity using an ionic conductive agent such as sulfate or sulfite.
[0015]
[Patent Document 1]
JP 11-323052 A (page 1-2)
[0016]
[Problems to be solved by the invention]
Although the polyvinylidene fluoride resin composition disclosed in Patent Document 1 is excellent in transparency, it has been difficult to color in a desired color tone. Generally, as a method of coloring a resin material excellent in transparency to an arbitrary color tone, various pigments are generally blended. However, when a pigment is blended with the semiconductive resin composition containing the ionic conductive agent as described above, the ionic conductive agent and the pigment cause a chemical reaction, which causes foaming or decomposition of the resin during melt kneading or molding. easy.
[0017]
For example, as a method for whitening a polyvinylidene fluoride resin composition, a method of blending a white inorganic pigment such as titanium oxide or barium titanate is generally used. However, when these white inorganic pigments are blended with a polyvinylidene fluoride resin composition containing an ionic conductive agent, the white inorganic pigment causes a chemical reaction with the ionic conductive agent, and foaming of the resin during melt kneading or molding And decomposition occurs.
[0018]
Accordingly, an object of the present invention is a polyvinylidene fluoride-based resin composition containing an ionic conductive agent, which has a volume resistivity in a semiconductive region, has little variation depending on the location of the volume resistivity, and has a tensile elasticity. A semiconducting resin composition having good mechanical properties such as elongation and elongation at break, heat resistance, flame retardancy, moldability (film forming property) and capable of being colored in a desired color tone including white It is in providing the manufacturing method.
[0019]
Moreover, the subject of this invention is providing the semiconductive sheet and electric charge control member which were shape | molded using the semiconductive resin composition which has such an outstanding characteristic.
[0020]
As a result of diligent research to achieve the above-mentioned problems, the present inventors have combined a non-crystalline polyester resin, a pigment, and an ionic conductive agent in a specific ratio with a polyvinylidene fluoride resin to obtain a white color. It was found that a semiconductive resin composition capable of being colored in a desired color tone including the above is obtained. The semiconductive resin composition of the present invention does not decompose or foam at the time of molding, the molded article obtained has good tensile modulus and tensile elongation at break, and has very little variation in volume resistivity depending on location. . Since the semiconductive resin composition of the present invention is mainly composed of a polyvinylidene fluoride resin, it is excellent in heat resistance and flame retardancy. The present invention has been completed based on these findings.
[0021]
[Means for Solving the Problems]
Thus, according to the present invention, (A) polyvinylidene fluoride resin 50 to 98.9% by mass, (B) amorphous polyester resin 0.5 to 20% by mass, and (C) pigment 0.5 to 20% by mass. % And (D) an ionic conductive agent in an amount of 0.1 to 10% by mass is provided.
[0022]
Moreover, according to the present invention, the semiconductive resin composition is melt-molded, and the average value of volume resistivity is 10³-10¹³A semiconductive sheet in the range of Ωcm is provided. Furthermore, according to the present invention, a charge control member molded from the semiconductive resin composition is provided.
[0023]
Furthermore, according to the present invention, (A) a mixture containing a polyvinylidene fluoride resin and (D) an ionic conductive agent, and (B) a mixture containing an amorphous polyester resin and (C) a pigment, A process for producing a semiconductive resin composition comprising a step of melt-kneading, and if necessary, melt-kneading a polyvinylidene fluoride resin or an amorphous polyester resin or both of them as required Provided.
[0024]
DETAILED DESCRIPTION OF THE INVENTION
1.Polyvinylidene fluoride resin:
The polyvinylidene fluoride resin used in the present invention includes a homopolymer of vinylidene fluoride (that is, polyvinylidene fluoride; hereinafter abbreviated as “PVDF”), vinylidene fluoride having a main constituent unit of vinylidene fluoride, and others. It is a copolymer with a copolymerizable monomer. The polyvinylidene fluoride resin is preferably a crystalline polymer. Since the polyvinylidene fluoride copolymer is a crystalline polymer, the copolymerization ratio of other copolymerizable monomer (comonomer) is usually less than 20 mol%, preferably less than 12 mol%, more preferably 10 mol%. It is desirable to be less than. Crystalline polyvinylidene fluoride resin usually has an α-type crystal structure. However, a polyvinylidene fluoride resin tends to have a β-type or γ-type crystal structure when, for example, tetraalkylammonium hydrogensulfate is blended.
[0025]
As the vinylidene fluoride copolymer, a vinylidene fluoride-hexafluoropropylene copolymer, a vinylidene fluoride-tetrafluoroethylene copolymer, or a vinylidene fluoride-tetrafluoroethylene-hexafluoropropylene copolymer is preferable. As mentioned. The polyvinylidene fluoride (PVDF) and the vinylidene fluoride copolymer can be used alone or in combination of two or more.
[0026]
Among the polyvinylidene fluoride resins, PVDF which is a homopolymer of vinylidene fluoride is preferable from the viewpoint of contamination resistance, ozone resistance, and solvent resistance. From the viewpoint of flexibility and tear strength, it is preferable to use a vinylidene fluoride copolymer having vinylidene fluoride as a main structural unit alone or blended with PVDF. In order to improve adhesiveness, a vinylidene fluoride copolymer into which a functional group is introduced is preferably used. The polyvinylidene fluoride resin may be used by blending other thermoplastic resins within a range not impeding the object of the present invention.
[0027]
2.Ionic conductive agent:
Examples of the ionic conductive agent used in the present invention include, but are not limited to, commercially available ionic electrolyte type antistatic agents, ionic surfactants, alkali metal salts, alkaline earth metals, and organic ionic electrolytes. . The ionic conductive agent is preferably one having heat resistance enough to withstand the melt processing temperature of the polyvinylidene fluoride resin. Among ionic conductive agents, perfluoroalkyl metal salts such as potassium perfluoroalkyl sulfonate and cesium perfluoroalkyl sulfonate; alkyl quaternary ammonium sulfate (ie, tetraalkyl ammonium sulfate), and alkyl quaternary ammonium sulfite Salts (ie tetraalkylammonium sulfites) are preferred.
[0028]
Tetraalkylammonium sulfate is represented by the following formula (1)
[0029]
[Chemical Formula 3]

[0030]
(Wherein R¹~ R⁴Are the same or different alkyl groups, and R⁵Is an alkyl group, a fluoroalkyl group or a hydrogen atom. )
It is a compound represented by these.
[0031]
Tetraalkylammonium sulfite is represented by the following formula (2)
[0032]
[Formula 4]

[0033]
(Wherein R⁶~ R⁹Are the same or different alkyl groups, and R¹⁰Is an alkyl group, a fluoroalkyl group or a hydrogen atom. )
It is a compound represented by these.
[0034]
In each compound represented by the formulas (1) and (2), the total number of carbon atoms of the alkyl group is preferably 8 to 30, more preferably 12 to 24, and particularly preferably 15 to 20. As the alkyl group, a short-chain alkyl group having 1 to 6 carbon atoms such as methyl group, ethyl group, propyl group, isopropyl group, n-butyl group, t-butyl group, pentyl group, and hexyl group is preferable. As the fluoroalkyl group, CF₃, C₂F₅Short chain fluoroalkyl groups such as are preferred.
[0035]
Specific examples of the compounds represented by formulas (1) and (2) include (C₂H₅)₄N⁺, (C₃H₇)₄N⁺, (C₄H₉)₄N⁺, (C₅H₁₁)₄N⁺Quaternary ammonium cations such as CF and CF₃SO₄ ⁻, CH₃SO₄ ⁻, HSO₄ ⁻, CF₃SO₃-CH₃SO₃ ⁻, HSO₃And a salt composed of sulfuric acid such as-or an anion containing sulfurous acid. These compounds may be salts in which two or more kinds of anions and / or cations are combined. Further, the four alkyl groups of quaternary ammonium may be the same or different. Among these, tetraalkylammonium hydrogen sulfate is preferable, and tetrabutylammonium hydrogen sulfate is particularly preferable.
[0036]
3.Amorphous polyester resin:
The amorphous polyester resin used in the present invention is essentially free from the detection of a peak having a heat of crystal melting (ΔH) of 10 J / g or more in the range of 100 to 300 ° C. by thermal analysis using a differential scanning calorimeter (DSC) It is preferably a non-crystalline polyester resin. The crystal melting heat (ΔH) is preferably 5 J / g or less, more preferably 3 J / g or less, and most preferably substantially zero J / g. Thus, it is desirable that the amorphous polyester resin used in the present invention is essentially non-crystalline and does not crystallize under any molding conditions.
[0037]
Amorphous polyester resin is obtained by replacing a part of dicarboxylic acid component and / or diol component of thermoplastic polyester resin such as polyethylene terephthalate (PET) and polybutylene terephthalate (PBT) with other copolymerization components, thereby improving the crystallinity. Copolyester that has been reduced or disappeared. The ratio of a copolymerization component is 20-50 mol% normally, Preferably it is 25-40 mol%, More preferably, it is 30-35 mol%. When the ratio of the copolymer component is too low, crystallinity appears in the polyester resin, the degree of crystallinity becomes high, and the tensile elongation at break and flexibility of a molded product such as a semiconductive sheet decrease.
[0038]
The amorphous polyester resin is an equimolar polycondensate of a dicarboxylic acid component and a diol component. The copolymerization ratio of each component is calculated based on a total of 200 mol% of the dicarboxylic acid component and the diol component. For example, a part of ethylene glycol (EG) of the diol component constituting the PET resin is replaced with 1,4-cyclohexanedimethanol (CHDM), and diol components composed of 70 mol% EG and 30 mol% CHDM (total 100 mol%) In this case, the proportion of repeating units formed from terephthalic acid and EG in the copolymer is 70 mol%, and the proportion of repeating units formed from terephthalic acid and CHDM is 30 mol%. In this case, the proportion of CHDM as a copolymerization component is referred to as 30 mol%.
[0039]
Examples of copolymer components include diol components such as propylene glycol, 1,4-butanediol, xylylene glycol, bisphenol A, diethylene glycol, and 1,4-cyclohexadimethanol; dicarboxylic acid components such as isophthalic acid, sebacic acid, and adipic acid And so on. These amorphous polyester resins can be used alone or in combination of two or more.
[0040]
Among the amorphous polyester resins used in the present invention, the dicarboxylic acid component is mainly composed of terephthalic acid, and the glycol component is mainly composed of ethylene glycol (EG) and 1,4-cyclohexanedimethanol (CHDM). The copolyester is preferred. More specifically, the amorphous polyester resin used in the present invention is preferably an amorphous polyethylene terephthalate copolymer (PETG) having 1,4-cyclohexanedimethanol as a copolymerization component. PETG is a copolyester in which a part of ethylene glycol (EG), which is a glycol component constituting the PET resin, is replaced with 1,4-cyclohexanedimethanol (CHDM). When a part of EG is replaced with CHDM for copolymerization, a copolyester having a crystallinity of substantially zero within a certain range of CHDM copolymerization (ie, PETG) is obtained.
[0041]
In the amorphous PETG, the proportion of CHDM in the glycol component is less than that of EG, preferably about 25 to 40 mol%, more preferably about 30 to 35 mol%. Correspondingly, the ratio of EG is preferably 60 to 75 mol%, more preferably 65 to 70 mol%. PETG is commercially available from Eastman Chemical Co. under the trade name EASTAR PETG6763 (CHDM = 31 ± 3 mol%). In the present invention, this commercially available product can be suitably used. Of course, if it is “essentially non-crystalline polyester resin in which a peak having a heat of crystal fusion (ΔH) of 10 J / g or more in the range of 180 to 300 ° C. is not detected by thermal analysis by DSC” as defined above. Other grades of commercial products and synthetic products can also be used.
[0042]
4).Pigment:
The pigment used in the present invention is not particularly limited, and various organic pigments and inorganic pigments can be mentioned, but it is necessary to have heat resistance sufficient not to decompose at the temperature when melt kneaded with the resin component. is there. Examples of the organic pigment used in the present invention include azo pigments such as insoluble azo pigments and condensed azo pigments; selenium pigments such as anthraquinone pigments, perinone pigments, perylene pigments, and thioindigo pigments; phthalocyanine blue, phthalocyanine Phthalocyanine pigments such as green; nitroso pigments such as naphthol green B and naphthol green Y; various pigments such as quinacridone pigments, dioxazine pigments, isoindolinone pigments, pyrrolopyrrole pigments, aniline black, and organic fluorescent pigments It is done.
[0043]
Examples of the inorganic pigment used in the present invention include natural products such as clay, barite, mica and ocher; chromates such as chrome lead, zinc yellow and barium yellow; ferrocyanides such as bitumen; and sulfides such as zinc sulfide. Products: sulfates such as barium sulfate; oxides such as chromium oxide, zinc oxide (zinc white), titanium oxide (titanium white), petal, iron black, chromium oxide; hydroxides such as aluminum hydroxide; silicic acid Silicates such as calcium and ultramarine; carbonates such as calcium carbonate and magnesium carbonate; carbon such as carbon black, pine smoke, bone black and graphite; metal powder such as aluminum powder, bronze powder and zinc powder; Can be mentioned.
[0044]
The pigments can be used alone or in combination of two or more. When whitening the semiconductive resin composition of the present invention, titanium oxide (titanium white; TiO2) is used as a white pigment.₂) Is preferably used. The titanium oxide is preferably one having a rutile crystal form. In addition to high whiteness and refractive index, titanium oxide generally has a particle size as small as 0.15 to 0.3 μm, and can form a highly conductive semiconductive resin composition.
[0045]
5.Semiconductive resin composition:
The resin composition of the present invention comprises (A) a polyvinylidene fluoride-based resin of 50 to 98.4% by mass, (B) an amorphous polyester of 1 to 20% by mass, (C) a pigment of 0.5 to 20% by mass, and (D) A semiconductive resin composition containing 0.1 to 10% by mass of an ionic conductive agent.
[0046]
The blending ratio of the polyvinylidene fluoride resin is in the range of 50 to 98.9% by mass, preferably 62 to 97.9% by mass, more preferably 73 to 97% by mass, and particularly preferably 82 to 96% by mass. . When the blending ratio of the polyvinylidene fluoride resin is too small, excellent properties such as mechanical properties, heat resistance and flame retardancy are deteriorated. If the blending ratio of the polyvinylidene fluoride resin is too large, the colorability and the conductivity will be insufficient.
[0047]
The blending ratio of the amorphous polyester resin is 0.5 to 20% by mass, preferably 0.8 to 15% by mass, more preferably 1 to 10% by mass, and particularly preferably 1 to 6% by mass. . If the blending ratio of the amorphous polyester resin is too small, the pigment is liable to cause a chemical reaction with the ionic conductive agent. If the blending ratio of the amorphous polyester resin is too large, the dispersibility of each component tends to be poor. In particular, when a semiconductive resin composition in which the blending ratio of the amorphous polyester resin is too large is extruded into a sheet, the tensile break elongation in the width direction (TD) of the sheet is remarkably reduced, and the sheet is easily teared in the flow direction. (That is, the sheet tears longitudinally).
[0048]
The blending ratio of the pigment is in the range of 0.5 to 20% by mass, preferably 0.8 to 15% by mass, more preferably 1 to 10% by mass, and particularly preferably 1 to 6% by mass. If the blending ratio of the pigment is too small, the degree of coloring tends to be insufficient, and when a white pigment is used, the whiteness of the resin composition tends to be low. If the blending ratio of the pigment is too large, the resin composition tends to become brittle.
[0049]
The mixing ratio of the ionic conductive agent is in the range of 0.1 to 10% by mass, preferably 0.5 to 8% by mass, more preferably 1 to 7% by mass, and particularly preferably 2 to 6% by mass. If the blending ratio of the ionic conductive agent is too small, it becomes difficult to obtain a resin composition having a volume resistivity in the semiconductive region. If the blending ratio of the ionic conductive agent is too large, the ionic conductive agent tends to be poorly dispersed, and the mechanical properties of the resin composition are lowered or the heat resistance is deteriorated.
[0050]
The blending ratio (mass ratio) of the (B) amorphous polyester resin and the (C) pigment is usually 1:20 to 40: 1, preferably 2: 8 to 8: 2, more preferably 3: 7 to 7: 3, particularly preferably within the range of 4: 6 to 6: 4. If the blending ratio of the amorphous polyester resin is too large, the degree of coloring tends to be insufficient, and in the case of a white pigment, it becomes difficult to obtain sufficient whiteness. If the blending ratio of the amorphous polyester resin is too small, the pigment is liable to cause a chemical reaction with the ionic conductive agent.
[0051]
The semiconductive resin composition of the present invention usually has a volume resistivity (average value) of 1.0 × 10.³~ 1.0 × 10¹³Ωcm, preferably 1.0 × 10⁵~ 1.0 × 10¹²Ωcm, more preferably 1.0 × 10⁶~ 1.5 × 10¹¹A semiconductive sheet and various molded articles that are in the range of Ωcm and exhibit volume resistivity in these ranges can be provided.
[0052]
If desired, the semiconductive resin composition of the present invention can be used other than antioxidants, lubricants, plasticizers, ultraviolet absorbers, pH adjusters, coupling agents, and pigments within the range not impairing the object of the present invention. A filler etc. can be added suitably.
[0053]
6).Process for producing semiconductive resin composition, molding method, and molded product
The semiconductive resin composition of the present invention can be produced by melt-kneading the above components. When the reactivity between the pigment and the ionic conductive agent is high, the amorphous polyester resin and the pigment are mixed using a kneader such as a single screw extruder, a twin screw extruder, a Banbury mixer, a roll mill, or a kneader. It is preferable to prepare a masterbatch (mixture) by melting and kneading. On the other hand, it is preferable that the polyvinylidene fluoride resin and the ionic conductive agent are previously melt-kneaded with the kneader to prepare a mixture. The latter mixture may be a master batch obtained by melting and kneading a high-concentration ionic conductive agent in a polyvinylidene fluoride resin. These master batches and mixtures are usually preferably pelletized.
[0054]
Therefore, a preferred method for producing the semiconductive resin composition is as follows: (A) a mixture containing a polyvinylidene fluoride resin and (D) an ionic conductive agent, (B) an amorphous polyester resin, and (C) a pigment. It is a manufacturing method including the process of melt-kneading the containing mixture (masterbatch). When these mixtures are melt-kneaded, if necessary, a polyvinylidene fluoride resin and / or an amorphous polyester resin can be blended and adjusted so that the ratio of each component is within a desired range. .
[0055]
Amorphous polyester resin has a higher surface energy than polyvinylidene fluoride resin, and therefore easily wets the surface of the pigment. On the other hand, since the polyvinylidene fluoride resin has a higher polarity than the amorphous polyester resin, it is easy to solvate the ionic conductive agent. For this reason, in the semiconductive resin composition of this invention, it is thought that the probability that a pigment and an ionic conductive agent will react directly becomes low.
[0056]
In particular, a mixture containing (A) a polyvinylidene fluoride resin and (D) an ionic conductive agent and a mixture containing (B) an amorphous polyester resin and (C) a pigment are melt-kneaded. Accordingly, when a manufacturing method including a step of adding and melting and kneading a polyvinylidene fluoride resin or an amorphous polyester resin or both of them, (A) the polyvinylidene fluoride resin forms a matrix, In addition, (C) a pigment-containing (B) amorphous polyester resin and (D) an ionic conductive agent can be dispersed to obtain a semiconductive resin composition, whereby the pigment and ions It is considered that the probability that the conductive conductive agent contacts and reacts directly can be further reduced.
[0057]
The method for molding the semiconductive resin composition of the present invention is not particularly limited, and is molded into, for example, a sheet, fiber, or other molded product by a general melt molding method such as injection molding or melt extrusion. can do. After molding, the molded product can be further stretched or heat-set. The semiconductive resin composition of the present invention may be used alone, or may be combined with other resin layers as necessary to form a laminated sheet or composite yarn.
[0058]
As a method of forming a semiconductive sheet using a semiconductive resin composition, a method of continuously extruding into a sheet form using a single or twin screw extruder and a T die may be adopted. preferable.
[0059]
The semiconductive sheet is formed by extruding the molten resin composition directly from the T die attached to the tip of the extruder directly under the lip of the T die, and cooling and solidifying it while closely contacting it with an air knife or the like on the cooling drum. Is preferably adopted. The semiconductive sheet is usually formed into a sheet form from a T die, but the semiconductive sheet can be directly formed into a shape such as a seamless belt or a tube using an annular die. As a desirable continuous melt extrusion method for seamless belts or tubes, a single screw extruder and a spiral annular die are used, and the molten resin composition is extruded from the lip of the annular die in an annular shape and annularly formed by an internal cooling mandrel system. A method of taking out while controlling the inner diameter of the body is mentioned.
[0060]
The semiconductive resin composition of the present invention can be directly molded into a seamless belt or a tube at the time of molding, but when it is molded into other normal sheet shape, the obtained semiconductive sheet is secondary By processing, various charge control members can be formed. One of the methods is forming an endless belt or a tube by a heating seam of a semiconductive sheet. In the case where the semiconductive sheet of the present invention is bonded with a heating seam and formed into a belt shape, the heating part (remelting part) of the sheet may be a part or the whole sheet.
[0061]
The semiconductive sheet of the present invention can be formed into a laminated belt by coating on a belt-like substrate (for example, a belt made of a polyimide film) formed from other materials. Further, the semiconductive sheet of the present invention may be laminated in two or more layers with other conductive sheets, semiconductive sheets, insulating sheets, or the like. For lamination, the interfaces of the layers may be bonded with an adhesive or may be formed as a multilayer sheet by coextrusion. Furthermore, the semiconductive sheet of the present invention can form a coating roller by coating on a roller-shaped substrate (for example, a cored bar). A tube formed from the semiconductive resin composition can be coated on the roller-shaped substrate.
[0062]
The surface of the semiconductive sheet or the charge control member of the present invention may be coated with another resin, vapor-deposited with metal, or matted depending on the application. However, when a desired color tone such as white is used as it is, it is preferably used without surface treatment. In particular, when the semiconductive sheet of the present invention is used as wallpaper, OA equipment exterior material, partition, or the like, it is preferable to use it without surface treatment in order to exhibit color tone.
[0063]
Although the thickness of the semiconductive sheet of this invention can be suitably determined according to a use, it is 20-1000 micrometers normally, Preferably it is 30-500 micrometers, More preferably, it is 40-250 micrometers, Especially preferably, it is 50-200 micrometers. If the thickness of the semiconductive sheet is too thin, the strength is lowered, and if it is too thick, the flexibility is lowered.
[0064]
The volume resistivity (average value) of the semiconductive sheet of the present invention is 1.0 × 10³~ 1.0 × 10¹³Ωcm, preferably 1.0 × 10⁵~ 1.0 × 10¹²Ωcm, more preferably 1.0 × 10⁶~ 1.5 × 10¹¹It is adjusted within the range of Ωcm, and the type and blending ratio of each component are adjusted so that the desired volume resistivity is obtained from this range depending on the application. Most of the charge control members of the present invention can be produced by secondary processing of a semiconductive sheet. Moreover, a semiconductive sheet is used as it is for wallpaper and OA equipment exterior materials.
[0065]
Thus, for example, when the semiconductive sheet is used as a developing roller coating tube, a photosensitive belt or roller coating tube, a static elimination belt or roller coating tube or a static elimination blade, the volume resistivity is preferably 1. 0x10⁵~ 1.0 × 10⁹Ωcm, more preferably 1.0 × 10⁶~ 1.0 × 10⁸Adjust within the range of Ωcm. When a semiconductive sheet is used as a paper conveying belt, its volume resistivity is preferably 1.0 × 10.⁵~ 1.0 × 10¹³Ωcm, more preferably 1.0 × 10⁸~ 1.0 × 10¹²Adjust within the range of Ωcm. When the semiconductive sheet is used as a transfer tube or roll coating tube, a charging belt or roll coating tube or a charging blade, the volume resistivity is preferably 1.0 × 10.⁵~ 1.0 × 10¹³Ωcm, more preferably 1.0 × 10⁷-10¹¹Adjust within the range of Ωcm.
[0066]
It is desirable that the semiconductive sheet has as little variation in volume resistivity as possible in order to exhibit a uniform charge control function. In order for the semiconductive sheet to function satisfactorily as a charge control member, the maximum value of volume resistivity is required to be within 30 times the minimum value. According to the present invention, the surface area is 1 m.²The maximum value of volume resistivity measured at 20 points arbitrarily selected per hit is usually 10 times or less of the minimum value, preferably 1 to 6 times, more preferably 1 to 4 times, particularly preferably 1 to 3 times. The semiconductive sheet can be obtained. The characteristic regarding the volume resistivity of such a semiconductive sheet corresponds with the characteristic of the electric charge control member formed using the semiconductive resin composition of this invention.
[0067]
When the charge control member is a transfer belt, for example, if the belt is distorted, the toner image formed on the belt may be distorted or the color may be shifted. Therefore, it is desirable that the semiconductive sheet has a sufficiently high elastic modulus, and it is desirable that the belt member has an appropriate flexibility so that the belt member does not break due to the inclusion of foreign matter or the like. The semiconductive sheet of the present invention has excellent tensile modulus and tensile elongation at break, and can meet the above requirements.
[0068]
Specifically, the semiconductive sheet of the present invention preferably has a tensile modulus of 0.7 GPa or more, more preferably 0.9 GPa or more, particularly preferably 1.0 GPa or more, and in many cases 1.2 GPa or more. can do. The upper limit of the tensile modulus is usually 4.0 GPa, and in many cases about 2.0 GPa.
[0069]
In general, the tensile elongation at break of the semiconductive sheet of the present invention shows a high value exceeding the measurement limit of 200% in the extrusion direction (MD) during extrusion molding. The tensile elongation at break in the transverse direction (TD) of the semiconductive sheet often varies depending on the blending ratio of the amorphous polyester resin, the ionic conductive agent and the pigment, but is preferably 5% or more, more preferably 10%. Above, particularly preferably 20% or more. By selecting the blending ratio of the amorphous polyester resin, the ionic conductive agent and the pigment, the tensile elongation at break in the transverse direction (TD) can be made 30% or more, further 40% or more.
[0070]
The parallel light transmittance of the semiconductive sheet or belt of the present invention is usually 30% or less, preferably 15% or less, more preferably 10% or less, and particularly preferably 5% or less.
[0071]
When the semiconductive resin composition of the present invention is used as a charge control member such as an intermediate transfer material belt or a paper conveyance belt, the color tone is preferably based on white, and the achromatic color based on white is an achromatic color. Particularly preferred is white, most preferred is white. The whiteness (W) of the semiconductive resin composition of the present invention is usually 60% or more, preferably 65% or more, more preferably 70% or more. The whiteness can be 75% or more, further 80% or more, if necessary. The yellowness (YI) of the semiconductive resin composition of the present invention is usually in the range of -20 to 20%, preferably -15 to 15%, more preferably -10 to 10%.
[0072]
The semiconductive sheet and charge control member of the present invention are colored in various colors according to the pigment used. Since the semiconductive resin composition of the present invention is mainly composed of a polyvinylidene fluoride resin, the semiconductive sheet and the charge control member formed from the resin composition are excellent in heat resistance and flame retardancy. Yes.
[0073]
【Example】
Hereinafter, the present invention will be described more specifically with reference to examples and comparative examples. The measuring method of physical properties is as follows.
(1) Thickness measurement:
The thickness of the molded product was measured using a dial gauge thickness meter (trade name: DG-911, manufactured by Ono Sokki Co., Ltd.).
[0074]
(2) Volume resistivity:
Ring probe (Mitsubishi Chemical Corporation, trade name URS probe; inner electrode outer diameter 5.9 mm, outer electrode inner diameter 11.0 mm, outer electrode outer diameter 17.8 mm) and measurement stage (Mitsubishi Chemical Corporation, product A sample is sandwiched between a nominal register table UFL) and pressed with a pressure of about 3 kg while applying a voltage of 100 V between the electrode inside the probe and the measurement stage, and a resistivity measuring device (Mitsubishi Chemical Co., Ltd.) The volume resistivity was determined under the trade name Hiresta UP). Details of the volume resistivity measurement method by the ring electrode method are described in JIS-K6911.
[0075]
(3) Calculation of average value:
The measurement of the thickness and volume resistivity described above is performed by measuring the surface area of the sample to be measured with these values.²The measurement was performed at 20 measurement points arbitrarily selected per hit, and the maximum value, minimum value, and average value (arithmetic average) were obtained.
[0076]
(4) Tensile modulus and tensile elongation at break:
In accordance with JIS K-7113, a strip-shaped test piece having a width of 10 mm and a length of 100 mm was prepared, and a tensile tester (made by Orientec Co., Ltd., trade name: Tensilon RTM100 type) with a tensile speed of 50 mm / min and a distance between chucks of 50 mm. It measured on condition of this.
[0077]
(5) Parallel light transmittance:
The parallel light transmittance was measured as “cloudiness value” using a Heizometer (manufactured by Nippon Denshoku Industries Co., Ltd., trade name Σ80). Details of the measurement method are described in JIS K-7105.
[0078]
(6) Thermal analysis by differential scanning calorimeter (DSC):
A sample (pellet) was subjected to thermal analysis under the following conditions using a differential scanning calorimeter (Metler, product name DSC30) and a data processor (Metler, product name TC10A). The sample was conditioned at 75 ° C. for 10 hours and then subjected to measurement. From the first run, the crystal melting peak temperature and the crystal melting heat (ΔH) were determined. The measurement conditions are a sample weight of 10 mg, a measurement start temperature of 30 ° C., a measurement end temperature of 300 ° C., and a temperature increase rate of 10 ° C./min.
[0079]
(7) Whiteness and yellowness:
Whiteness (W) and yellowness (YI) were measured using a color meter (manufactured by Nippon Denshoku Industries Co., Ltd., trade name ZE2000). Details of whiteness and yellowness are described in JIS P-8715 and JIS Z-8715.
[0080]
[Examples 1 to 4, Comparative Examples 1 to 6]
A raw material having the composition shown in Table 1 is supplied to a single screw extruder, melt-extruded into a sheet form from a T die having a lip clearance of 0.7 mm, immediately cooled by a cooling roll at 80 ° C., and a sheet having a thickness of about 50 μm ( Film). However, for the ionic conductive agent, pellets obtained by adding a predetermined amount of ionic conductive agent to PVDF were prepared in advance, and blended with other components during film formation. In Examples 1 to 4, master batch pellets in which a pigment was blended in an amorphous polyester resin at a concentration of 50% by mass were prepared in advance and blended with other components during film formation. The results are shown in Tables 1 and 2. The semiconductive resin compositions of Examples 1 to 4 were white. In the case of the ratio formulation of Comparative Example 2, the resin component was decomposed and foamed, and could not be formed into a sheet.
[0081]
[Table 1]

[0082]
(footnote)
(1) PVDF: polyvinylidene fluoride resin (Kureha Chemical Industries, KF # 1000)
(2) TBAHS: Tetrabutylammonium hydrogen sulfate [(C₄H₉)₄NHSO₄Manufactured by Guangei Chemical Co., Ltd.)
(3) PETG: Amorphous polyester resin (Eastman Chemical, EASTER6763; no DSC crystal melting peak temperature between 100-300 ° C)
(4) TiO₂: Titanium oxide powder (D101, R101)
[0083]
[Table 2]

[0084]
【The invention's effect】
ADVANTAGE OF THE INVENTION According to this invention, the semiconductive resin composition which can shape | mold the molding which has arbitrary volume resistivity of a semiconductive area | region, and can be colored to a desired color tone, its manufacturing method, this resin composition There are provided a semiconductive sheet obtained by melt-molding a product, and a charge control member formed from the resin composition. The semiconductive resin composition of the present invention is suitable as a resin material for various charge control members, dust adsorption-preventing wallpaper and OA equipment exterior materials in electrophotographic and inkjet image forming apparatuses.

Claims (17)

(A) 50-98.9% by mass of polyvinylidene fluoride resin,
(B) Amorphous polyester resin 0.5-20% by mass,
(C) 0.5 to 20% by mass of pigment, and (D) 0.1 to 10% by mass of ionic conductive agent.
Containing a semiconductive resin composition. (A) A polyvinylidene fluoride resin forms a matrix, and (B) an amorphous polyester resin containing (C) a pigment and (D) an ionic conductive agent are dispersed in the matrix. The semiconductive resin composition according to claim 1. The semiconductive resin composition according to claim 1 or 2, wherein (A) the polyvinylidene fluoride resin is a homopolymer of vinylidene fluoride. (B) The amorphous polyester resin is a polycondensate of a dicarboxylic acid component and a diol component, contains terephthalic acid as the dicarboxylic acid component, and 25 to 40 mol% 1,4-cyclohexanedi as the diol component The semiconductive resin composition according to any one of claims 1 to 3, which is an amorphous polyethylene terephthalate copolymer containing methanol and 60 to 75 mol% of ethylene glycol. The semiconductive resin composition according to any one of claims 1 to 4, wherein the pigment (C) is titanium dioxide. (D) The ionic conductive agent has the formula (1)

(In the formula, R ^{1 to} R ⁴ are the same or different alkyl groups, and R ⁵ is an alkyl group, a fluoroalkyl group, or a hydrogen atom.)
A tetraalkylammonium sulfate represented by the formula (2)

(In the formula, R ^{6 to} R ⁹ are the same or different alkyl groups, and R ¹⁰ is an alkyl group, a fluoroalkyl group, or a hydrogen atom.)
The semiconductive resin composition according to any one of claims 1 to 5, which is a tetraalkylammonium sulfite represented by the following formula: The semiconductive resin composition according to claim 6, wherein (D) the ionic conductive agent is a tetraalkylammonium hydrogensulfate in which R ⁵ is a hydrogen atom in formula (1). (D) The semiconductive resin according to claim 6, wherein the ionic conductive agent is tetrabutylammonium hydrogen sulfate in which R ^{1 to} R ⁴ are butyl groups and R ⁵ is a hydrogen atom in formula (1). Composition. It melt-molds from the semiconductive resin composition of any one of Claims 1 thru | or 8, and the average value of volume resistivity exists in the range of 1.0 * 10 < ³ > -1.0 * 10 < ¹³ > ohm-cm. Semiconductive sheet. The semiconductive sheet according to claim 9, wherein the parallel light transmittance is 30% or less and the whiteness is 60% or more. The semiconductive sheet according to claim 9 or 10, wherein a maximum value of volume resistivity measured at 20 points arbitrarily selected per 1 m ^{2 of} surface area is 10 times or less of a minimum value. A charge control member formed from the semiconductive resin composition according to any one of claims 1 to 8. 13. The charge control member according to claim 12, wherein the charge control member is a semiconductive belt, a semiconductive tube, or a semiconductive blade. 13. The charge control member according to claim 12, wherein the charge control member is a multilayer belt or a coated roller in which a coating layer of a semiconductive resin composition is formed on a belt-shaped or roller-shaped substrate. 15. The charge control member according to claim 12, which is a semiconductive member mounted on an electrophotographic image forming apparatus or an ink jet printer. 13. The charge control member according to claim 12, wherein the charge control member is wallpaper, OA equipment exterior material, or a partition. (A) A mixture containing a polyvinylidene fluoride-based resin and (D) an ionic conductive agent, and (B) a mixture containing an amorphous polyester resin and (C) a pigment are melt-kneaded. Accordingly, a process for producing a semiconductive resin composition, comprising a step of adding a polyvinylidene fluoride resin, an amorphous polyester resin, or both, and melt-kneading them.