JP2004126178A - Fixing roll and highly thermal conductive silicone rubber composition for fixing roll - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a silicone rubber composition providing a silicone rubber which has excellent thermal conductivity, a little permanent compressive strain, and excellent long-term durability at a high temperature and is suitable as a covering material for a fixing roll, in particular a heat roll, and to provide the fixing roll in which a silicone rubber layer comprising the cured composition is formed on the circumferential surface of a metal core. <P>SOLUTION: The composition is characterized by containing: (A) liquid organo-polysiloxane containing an alkenyl group combined with at least two silicon atoms in one molecule; (B) liquid organo hydrogen polysiloxane containing three hydrogen atoms combined with at least a silicon atom in one molecule; (C) one or more kinds selected from siloxane compounds having a specific structure; (D) thermally conductive inorganic fine particles; and (E) an addition reaction catalyst. <P>COPYRIGHT: (C)2004,JPO

Description

（式中、Ｒ^１は同一又は異種の炭素原子数１〜１０の非置換又は置換１価炭化水素基、Ｘ^１は炭素原子数１〜４のアルコキシ基又はアシロキシ基、ａは０〜２の整数、ｊは０〜１００の整数である。）
【化５】

（式中、Ｒ^２は同一又は異種の炭素原子数１〜１０の非置換又は置換１価炭化水素基、Ｘ^２は炭素原子数１〜４のアルコキシ基又はアシロキシ基、ｂは０〜２の整数、ｋは０〜１００の整数である。）
【化６】

（式中、Ｒ^３は同一又は異種の炭素原子数１〜１０の非置換又は置換１価炭化水素基、Ｘ^３は炭素原子数１〜４のアルコキシ基又はアシロキシ基、Ｚは酸素原子又は炭素原子数２〜１０の２価炭化水素基、ｃは０〜２の整数、ｎは０〜１００の整数、ｍは１〜１０の整数である。）
で示されるシロキサン化合物から選ばれる１種又は２種以上：０．１〜３０重量部
（Ｄ）熱伝導性無機粉体：５０〜１，０００重量部
（Ｅ）付加反応触媒：触媒量
を含有することを特徴とする定着ロール用高熱伝導性シリコーンゴム組成物、及び芯金の外周面上にシリコーンゴム層が形成されてなる定着ロールであって、該シリコーンゴム層を形成するシリコーンゴムが上記シリコーンゴム組成物を硬化させてなるものであることを特徴とする定着ロールを提供する。
【００１０】
以下、本発明につき更に詳述する。
本発明の定着ロール用高熱伝導性シリコーンゴム組成物において、（Ａ）成分の液状オルガノポリシロキサンは、１分子中に少なくとも２個の珪素原子と結合するアルケニル基を有し、２５℃での粘度が１００，０００ｍＰａ・ｓ以下、好ましくは１００〜５０，０００ｍＰａ・ｓのものである。
【００１１】
上記オルガノポリシロキサンとしては、例えば、下記平均組成式（４）
Ｒ_ｄＳｉＯ_{（４−ｄ）／２}　　　（４）
（式中、Ｒは互いに同一又は異種の炭素原子数１〜１０、好ましくは１〜８の非置換又は置換１価炭化水素基であり、ｄは１．５〜２．８、好ましくは１．８〜２．５の範囲の正数である。）
で示され、Ｒとして、１分子中に少なくとも２個のアルケニル基（炭素原子数が好ましくは２〜８、特に好ましくは２〜６）を有するものが挙げられる。このアルケニル基としては、ビニル基、アリル基、プロペニル基、イソプロペニル基、ブテニル基、ヘキセニル基、シクロヘキセニル基、オクテニル基が挙げられるが、特にビニル基が好ましい。
【００１２】
また、上記アルケニル基の含有量は、オルガノポリシロキサン中１．０×１０^−６〜５．０×１０^−３ｍｏｌ／ｇ、特に５．０×１０^−６〜１．０×１０^−３ｍｏｌ／ｇであることが好ましい。アルケニル基の含有量が１．０×１０^−６ｍｏｌ／ｇより少ないと架橋が不十分でゲル状になってしまうおそれがあり、また５．０×１０^−３ｍｏｌ／ｇより多いと架橋密度が高くなりすぎて、脆いゴムとなってしまうおそれがある。なお、上記アルケニル基は、分子鎖末端の珪素原子に結合していても、分子鎖途中の珪素原子に結合していても、両者に結合していてもよい。
【００１３】
一方、上記Ｒで示される１価炭化水素基のうちアルケニル基以外ものとしては、メチル基、エチル基、プロピル基、イソプロピル基、ブチル基、イソブチル基、ｔｅｒｔ−ブチル基、ペンチル基、ネオペンチル基、ヘキシル基、シクロヘキシル基、オクチル基、ノニル基、デシル基等のアルキル基、フェニル基、トリル基、キシリル基、ナフチル基等のアリール基、ベンジル基、フェニルエチル基、フェニルプロピル基等のアラルキル基や、これらの基の水素原子の一部又は全部をフッ素、臭素、塩素等のハロゲン原子、シアノ基等で置換したもの、例えばクロロメチル基、クロロプロピル基、ブロモエチル基、トリフロロプロピル基、シアノエチル基などが挙げられる。なお、全Ｒ中の９０％以上がメチル基であることが好ましい。
【００１４】
また、上記オルガノポリシロキサンの構造は、基本的には直鎖状構造を有するものが好ましいが、部分的には分岐状の構造、環状構造などであってもよい。
【００１５】
（Ｂ）成分の液状オルガノハイドロジェンポリシロキサンは、１分子中に少なくとも珪素原子と結合する水素原子（Ｓｉ−Ｈ基）を３個含有し、２５℃での粘度が１，０００ｍＰａ・ｓ以下のものである。このオルガノハイドロジェンポリシロキサンは、分子中のＳｉ−Ｈ基と前記（Ａ）成分中のオルガノポリシロキサンの珪素原子に結合したアルケニル基とが、ヒドロシリル付加反応により架橋することにより組成物を硬化させるための硬化剤として作用するものである。
【００１６】
（Ｂ）成分の上記オルガノハイドロジェンポリシロキサンとしては、例えば、下記平均組成式（５）
Ｒ’_ｅＨ_ｆＳｉＯ_{｛４−（ｅ＋ｆ）｝／２}　　　（５）
（式中、Ｒ’は互いに同一又は異種の炭素原子数１〜１０、好ましくは１〜８の非置換又は置換１価炭化水素基であり、ｅ，ｆは、ｅ＝０．７〜２．１、好ましくは０．８〜２．０、ｆ＝０．００１〜１．０、好ましくは０．０１〜１．０、かつｅ＋ｆ＝０．８〜３．０、好ましくは１．０〜２．５を満足する正数である。）
で示され、１分子中に少なくとも３個、好ましくは３〜１００個、より好ましくは３〜５０個の珪素原子に結合した水素原子（Ｓｉ−Ｈ基）を有するものが挙げられる。
【００１７】
ここでＲ’の１価炭化水素基としては、上記平均組成式（４）のＲとして例示したものと同様のものを挙げることができるが、脂肪族不飽和基を有しないものが好ましい。また、このオルガノハイドロジェンポリシロキサンの分子構造は、直鎖状、環状、分岐状、三次元網目状等いずれの構造であってもよく、１分子中の珪素原子の数（又は重合度）は２〜３００個、特に４〜１５０個程度の室温（２５℃）で液状のものが好適に用いられる。なお、珪素原子に結合する水素原子は分子鎖末端、分子鎖の途中のいずれに位置していてもよく、両方に位置するものであってもよい。
【００１８】
このようなオルガノハイドロジェンポリシロキサンとしてより具体的には、両末端トリメチルシロキシ基封鎖メチルハイドロジェンポリシロキサン、両末端トリメチルシロキシ基封鎖ジメチルシロキサン・メチルハイドロジェンシロキサン共重合体、両末端ジメチルハイドロジェンシロキシ基封鎖ジメチルシロキサン、両末端ジメチルハイドロジェンシロキシ基封鎖ジメチルシロキサン・メチルハイドロジェンシロキサン共重合体、両末端トリメチルシロキシ基封鎖メチルハイドロジェンシロキサン・ジフェニルシロキサン共重合体、両末端トリメチルシロキシ基封鎖メチルハイドロジェンシロキサン・ジフェニルシロキサン・ジメチルシロキサン共重合体、（ＣＨ_３）_２ＨＳｉＯ_１／２単位とＳｉＯ_４／２単位とからなる共重合体、（ＣＨ_３）_２ＨＳｉＯ_１／２単位とＳｉＯ_４／２単位と（Ｃ_６Ｈ_５）_３ＳｉＯ_３／２単位とからなる共重合体などが挙げられる。
【００１９】
なお、上記（Ｂ）成分のオルガノハイドロジェンポリシロキサンの配合量は、（Ａ）成分のオルガノポリシロキサン１００重量部に対して０．１〜３０重量部、好ましくは０．３〜２０重量部である。
【００２０】
本発明のシリコーンゴム組成物においては、（Ｃ）成分として、下記一般式（１）〜（３）
【００２１】
【化７】

（式中、Ｒ^１は同一又は異種の炭素原子数１〜１０、好ましくは１〜８の非置換又は置換１価炭化水素基、Ｘ^１は炭素原子数１〜４のアルコキシ基又はアシロキシ基、ａは０〜２の整数、ｊは０〜１００、好ましくは５〜１００、より好ましくは１０〜８０の整数である。）
【００２２】
【化８】

（式中、Ｒ^２は同一又は異種の炭素原子数１〜１０、好ましくは１〜８の非置換又は置換１価炭化水素基、Ｘ^２は炭素原子数１〜４のアルコキシ基又はアシロキシ基、ｂは０〜２の整数、ｋは０〜１００、好ましくは５〜１００、よりこのましくは１０〜８０の整数である。）
【００２３】
【化９】

（式中、Ｒ^３は同一又は異種の炭素原子数１〜１０、好ましくは１〜８の非置換又は置換１価炭化水素基、Ｘ^３は炭素原子数１〜４のアルコキシ基又はアシロキシ基、Ｚは酸素原子又は炭素原子数２〜１０の２価炭化水素基、ｃは０〜２の整数、ｎは０〜１００、好ましくは０〜８０、より好ましくは０〜３０の整数、ｍは１〜１０、好ましくは１〜５の整数である。）
で示される分子中に珪素原子と結合する加水分解性基（アルコキシ基又はアシロキシ基）を有するオルガノポリシロキサンから選ばれる１種又は２種以上を配合する。
【００２４】
上記Ｒ^１，Ｒ^２，Ｒ^３として、具体的にはメチル基、エチル基、プロピル基、イソプロピル基、ブチル基、イソブチル基、ｔｅｒｔ−ブチル基、ペンチル基、ネオペンチル基、ヘキシル基、シクロヘキシル基、オクチル基、ノニル基、デシル基等のアルキル基、フェニル基、トリル基、キシリル基、ナフチル基等のアリール基、ベンジル基、フェニルエチル基、フェニルプロピル基等のアラルキル基、ビニル基、アリル基、プロペニル基、イソプロペニル基、ブテニル基、ヘキセニル基、シクロヘキセニル基、オクテニル基等のアルケニル基や、これらの基の水素原子の一部又は全部をフッ素、臭素、塩素等のハロゲン原子、シアノ基等で置換したもの、例えばクロロメチル基、クロロプロピル基、ブロモエチル基、トリフロロプロピル基、シアノエチル基などが挙げられる。なお、全Ｒ^１の５０％以上がメチル基であることが好ましく、同様に全Ｒ^２、全Ｒ^３も各々５０％以上がメチル基であることが好ましい。
【００２５】
また、上記一般式（１）〜（３）のシロキサン化合物のＲ^１，Ｒ^２，Ｒ^３としてアルケニル基を挙げることもできる。このアルケニル基としては、炭素原子数が２〜８、特に２〜６であるものが好ましく、このようなアルケニル基としては、ビニル基、アリル基、プロペニル基、イソプロペニル基、ブテニル基、ヘキセニル基、シクロヘキセニル基、オクテニル基が挙げられるが、中でもビニル基が特に好ましい。この場合、これらの（Ｃ）成分のシロキサン化合物中のアルケニル基の含有量は、１．０×１０^−２ｍｏｌ／ｇ以下、通常０〜１．０×１０^−２ｍｏｌ／ｇ、特に１．０×１０^−６〜１．０×１０^−２ｍｏｌ／ｇ程度となる量とすることが好ましい。なお、（Ｃ）成分のシロキサン化合物は、勿論アルケニル基を含まないものであってもよい。
【００２６】
一方、上記式中のＸ^１，Ｘ^２，Ｘ^３は、炭素原子数１〜４のアルコキシ基又はアシロキシ基であるが、このアルコキシ基又はアシロキシ基としては、例えばメトキシ基、エトキシ基、ｎ−プロポキシ基、イソプロポキシ基、ｎ−ブトキシ基、アセトキシ基等が挙げられる。また、上記式中のＺは、酸素原子又は炭素原子数２〜１０の２価炭化水素基であるが、この２価炭化水素基としては、エチレン基、プロピレン基、ブチレン基等のアルキレン基などが挙げられる。
【００２７】
なお、上記（Ｃ）成分のシロキサン化合物の配合量は、（Ａ）成分のオルガノポリシロキサン１００重量部に対して０．１〜３０重量部、好ましくは１〜２０重量部である。配合量が０．１重量部未満では圧縮永久歪が小さくならず、３０重量部を超えると得られるゴム硬化物のロール被覆材としてのゴム物性に悪影響を与えてしまう。
【００２８】
（Ｄ）成分の熱伝導性無機粉体としては、熱伝導性を有する各種充填剤を使用することができる。具体的には、石英粉、珪藻土、酸化アルミニウム（アルミナ）、水酸化アルミニウム、酸化亜鉛、炭化珪素、窒化珪素、酸化マグネシウム、窒化アルミニウム、窒化ホウ素などが挙げられ、特に、石英粉とアルミナが好適に用いられる。
【００２９】
このような熱伝導性無機粉体としては、その平均粒子径が０．１〜５０μｍ、好ましくは０．５〜４０μｍであるものを使用することが好ましい。平均粒子径が０．１μｍ未満の粒子は、製造が困難であると共に、多量に配合するのが困難となる場合があり、５０μｍを超える粒子では、ゴム硬化物の機械的強度が損なわれる場合があるだけでなく、ロールとしての表面性能等に問題が生じてしまうおそれがある。なお、上記平均粒子径は、例えばレーザー光回折法等の分析手段を使用した粒度分布計により、重量平均値（又はメジアン径）等として求めることができる。
【００３０】
また、これら熱伝導性無機粉体は、１種のみを用いても、２種以上を併用してもよい。更に、同種のもの、例えばアルミナでも、平均粒子径、製造方法、純度、表面処理の有無などが異なる２品種以上を併用してもよい。
【００３１】
なお、上記（Ｄ）成分の熱伝導性無機粉体の配合量は、（Ａ）成分のオルガノポリシロキサン１００重量部に対して５０〜１，０００重量部、好ましくは１００〜８００重量部である。５０重量部未満では、高熱伝導性が得られず、１，０００重量部を超えると配合が困難となるばかりでなく、得られるゴム硬化物のロール被覆材としてのゴム物性も著しく低下させてしまう。
【００３２】
これら熱伝導性無機粉体は、常温でプラネタリーミキサーやニーダーなどの機器を用いて組成物中に混合することができる。また、混合温度は常温でも加熱下でもよいが、上記（Ｂ）成分のオルガノハイドロジェンポリシロキサン及び後述する（Ｅ）成分である触媒を添加する前であれば、１００〜２００℃の高温下で混合することもできる。
【００３３】
（Ｅ）成分の付加反応触媒としては、白金黒、塩化第２白金、塩化白金酸、塩化白金酸と１価アルコ−ルとの反応物、塩化白金酸とオレフィン類との錯体、白金ビスアセトアセテ−ト等の白金系触媒、パラジウム系触媒、ロジウム系触媒などの白金族金属系触媒が挙げられる。なお、この付加反応触媒の配合量は触媒量、即ち、組成物を硬化するために必要な量であり、通常、金属量としてとして（Ａ）成分及び（Ｂ）成分の合計量に対し、０．５〜１，０００ｐｐｍ、特に１〜５００ｐｐｍ程度であることが好ましい。
【００３４】
上記シリコーンゴム組成物には、必要に応じてシリカヒドロゲル（含水珪酸）、シリカエアロゲル（無水珪酸−煙霧質シリカ）などの補強性シリカ充填剤、クレイ、炭酸カルシウム、二酸化チタン等の充填剤、酸化鉄、酸化セリウム、オクチル酸鉄等の耐熱性向上剤、接着性や成形加工性を向上させるための各種カーボンファンクショナルシラン、難燃性を付与させる窒素化合物、ハロゲン化合物を添加混合してもよい。
【００３５】
なお、上記シリコーンゴム組成物の硬化物の熱伝導率は０．５Ｗ／（ｍ・Ｋ）以上であることが好ましく、より好ましくは０．６Ｗ／（ｍ・Ｋ）以上である。その上限は特に制限されないが、通常５Ｗ／（ｍ・Ｋ）以下である。
【００３６】
本発明の定着ロールは、芯金（ロール軸）に上記シリコーンゴム組成物の硬化物であるシリコーンゴム層を形成したものであるが、この場合、芯金の材質、寸法等はロールの種類に応じて適宜選定し得る。また、シリコーンゴム組成物の成形、硬化法も適宜選定し得、例えば注入成形、移送成形、射出成形、コーティング等の成形法により成形でき、組成物は加熱により硬化できる。
【００３７】
また、上記シリコーンゴム層の外周面上に、更にフッ素樹脂層又はフッ素ゴム層を設けてもよい。この場合、フッ素樹脂層は、フッ素系樹脂コーティング材やフッ素系樹脂チューブなどにより形成できる。フッ素系樹脂コーティング材を用いる場合は、例えばポリテトラフルオロエチレン樹脂（ＰＴＦＥ）のラテックスや、ダイエルラテックス（ダイキン工業社製、フッ素系ラテックス）等を上記シリコーンゴム層の外周面上に積層すればよい。
【００３８】
フッ素系樹脂チューブとしては市販品を使用し得、この場合は、例えばポリテトラフルオロエチレン樹脂（ＰＴＦＥ）、テトラフルオロエチレン−パーフルオロアルキルビニルエーテル共重合体樹脂（ＰＦＡ）、フッ化エチレン−プロピレン共重合体樹脂（ＦＥＰ）、ポリフッ化ビニリデン樹脂（ＰＶＤＦ）、ポリフッ化ビニル樹脂等のチューブを用い、芯金と上記チューブとの間に前記シリコーンゴム組成物を充填して硬化させる方法によりシリコーン樹脂層を形成することができる。なお、上記シリコーン樹脂層としては、特にＰＦＡチューブを用いたものが好ましい。
【００３９】
一方、フッ素ゴムとしては、市販品のフッ素ゴムチューブを使用し得、樹脂チューブの場合と同様の方法で、フッ素ゴム層を形成することができる。
【００４０】
【実施例】
以下、実施例及び比較例を示し、本発明を具体的に説明するが、本発明は下記実施例に制限されるものではない。なお、以下の例において、部はいずれも重量部である。
【００４１】
［実施例１］
（Ａ）成分として両末端がジメチルビニルシロキシ基で封鎖されたジメチルポリシロキサン（重合度２００）１００部、補強性シリカ充填剤として比表面積が１１０ｍ^２／ｇである疎水化処理されたヒュームドシリカ（日本アエロジル社製Ｒ−９７２）２部、（Ｃ）成分として下記一般式（Ｉ）で示されるシロキサン化合物３部、
【００４２】
【化１０】

（Ｄ）成分として平均粒子径が４μｍのアルミナ６０部及び平均粒子径が１５μｍのアルミナ２２０部をプラネタリーミキサーに入れ、室温（２３℃）で２時間攪拌した。
【００４３】
この混合物を３本ロールにかけて、更に充填剤を分散させた後、再びプラネタリーミキサーに戻し、（Ｂ）成分として両末端及び側鎖にＳｉ−Ｈ基を有するメチルハイドロジェンポリシロキサン（重合度１７、Ｓｉ−Ｈ基量０．００６０ｍｏｌ／ｇ）を２．５部、反応制御剤としてエチニルシクロヘキサノール０．０５部、（Ｅ）成分として白金触媒（Ｐｔ濃度１％）０．１部を添加し、１５分撹拌してシリコーンゴム組成物を得た。
【００４４】
このシリコーンゴム組成物を用い、１２０℃で１０分間プレスキュアし、更に２００℃で４時間オーブンキュアしてシリコーンゴム硬化物サンプルを作成し、ＪＩＳ　Ｋ　６３０１に準拠して、硬さ及び圧縮永久歪を測定した。また、熱伝導率を熱伝導計ＱＴＭ−３（京都電子社製）で測定した。結果を表１に示す。
【００４５】
［比較例１］
上記一般式（Ｉ）で示されるシロキサン化合物を添加しない以外は、実施例１と同様にしてシリコーンゴム組成物を得、実施例１と同様の方法で硬化物サンプルを作成し、物性を測定した。結果を表１に示す。
【００４６】
［実施例２］
（Ａ）成分として両末端がトリメチルシロキシ基で封鎖され、側鎖にビニル基（ビニル基含有量　０．０００１ｍｏｌ／ｇ）を有するジメチルポリシロキサン（重合度５００）８０部及び両末端がジメチルビニルシロキシ基で封鎖されたジメチルポリシロキサン（重合度２００）２０部、補強性シリカ充填剤として比表面積が１１０ｍ^２／ｇである疎水化処理されたヒュームドシリカ（日本アエロジル社製　Ｒ−９７２）２部、（Ｃ）成分として、下記一般式（ＩＩ）で示されるシロキサン化合物５部、
【００４７】
【化１１】

（Ｄ）成分として平均粒子径が５μｍの石英粉８０部及び平均粒子径が１５μｍのアルミナ１２０部をプラネタリーミキサーに入れ、１５０℃で２時間攪拌した。
【００４８】
この混合物を３本ロールにかけて、更に充填剤を分散させた後、再びプラネタリーミキサーに戻し、（Ｂ）成分として両末端及び側鎖にＳｉ−Ｈ基を有するメチルハイドロジェンポリシロキサン（重合度１７、Ｓｉ−Ｈ基量０．００６０ｍｏｌ／ｇ）を２．１部、反応制御剤としてエチニルシクロヘキサノール０．０５部、白金触媒（Ｐｔ濃度１％）０．１部を添加し、１５分撹拌してシリコーンゴム組成物を得た。
【００４９】
このシリコーンゴム組成物を用い、実施例１と同様の方法で硬化物サンプルを作成し、物性を測定した。結果を表１に示す
【００５０】
［比較例２］
上記一般式（ＩＩ）で示されるシロキサン化合物を添加しない以外は、実施例２と同様にしてシリコーンゴム組成物を得、実施例１と同様の方法で硬化物サンプルを作成し、物性を測定した。結果を表１に示す。
【００５１】
［実施例３］
（Ａ）成分として両末端がジメチルビニルシロキシ基で封鎖されたジメチルポリシロキサン（重合度２００）５０部及び両末端がジメチルビニルシロキシ基で封鎖されたジメチルポリシロキサン（重合度５００）５０部、（Ｃ）成分として下記一般式（ＩＩＩ）で示されるシロキサン化合物８部、
【００５２】
【化１２】

（Ｄ）成分として平均粒子径が４μｍのアルミナ１００部及び平均粒子径が１０μｍの酸化亜鉛２８０部をプラネタリーミキサーに入れ、室温（２３℃）で２時間攪拌した。
【００５３】
この混合物を３本ロールにかけて、更に充填剤を分散させた後、再びプラネタリーミキサーに戻し、（Ｂ）成分として両末端及び側鎖にＳｉ−Ｈ基を有するメチルハイドロジェンポリシロキサン（重合度１７、Ｓｉ−Ｈ基量０．００６０ｍｏｌ／ｇ）を５．８部、反応制御剤としてエチニルシクロヘキサノール０．０５部、白金触媒（Ｐｔ濃度１％）０．１部を添加し、１５分撹拌してシリコーンゴム組成物を得た。
【００５４】
このシリコーンゴム組成物を用い、実施例１と同様の方法で硬化物サンプルを作成し、物性を測定した。結果を表１に示す
【００５５】
［比較例３］
上記一般式（ＩＩＩ）で示されるシロキサン化合物を添加しない以外は、実施例３と同様にしてシリコーンゴム組成物を得、実施例１と同様の方法で硬化物サンプルを作成し、物性を測定した。結果を表１に示す。
【００５６】
【表１】

圧縮永久歪測定条件：１８０℃×２２時間，２５％圧縮
【００５７】
［実施例４］
表面に付加反応型液状シリコーンゴム用プライマーＮｏ．１０１Ａ／Ｂ（信越化学工業社製）を塗付した直径１０ｍｍ×長さ３００ｍｍのアルミニウムシャフトを金型内に固定し、実施例１で得たシリコーンゴム組成物を金型内に１０ｋｇ／ｃｍ^２で充填し、１５０℃で３０分加熱硬化し、更に２００℃で４時間ポストキュアして、アルミニウムシャフトの外周面上に外径２０ｍｍ×長さ２５０ｍｍのシリコーンゴム層が形成された定着ロールを得た。この定着ロールを電子写真複写機に装着してＡ４サイズの複写紙を１０万枚連続複写したが、紙しわや紙づまりなどは発生せず、また、複写された画像はすべて鮮明であった。
【００５８】
［比較例４］
比較例１で得たシリコーンゴム組成物を用いた以外は実施例４と同様の方法にて定着ロールを得、この定着ロールを電子写真複写機に装着してＡ４サイズの複写紙を連続複写したところ、約８万枚を超えたところで紙しわや紙づまりが発生した。
【００５９】
［比較例５］
比較例２で得たシリコーンゴム組成物を用いた以外は実施例４と同様の方法にて定着ロールを得、この定着ロールを電子写真複写機に装着してＡ４サイズの複写紙を連続複写したところ、約７万枚を超えたところで紙しわや紙づまりが発生した。
【００６０】
［実施例５］
内面に付加反応型液状シリコーンゴム用プライマーＮｏ．１０１Ａ／Ｂ（信越化学工業社製）を塗付した外径２０ｍｍ、長さ２５０ｍｍ、厚さ５０μｍのＰＦＡ樹脂チューブの内側に、表面に上記プライマーを塗付した直径１０ｍｍ×長さ３００ｍｍのアルミニウムシャフトを上記チューブの内面から等距離になる位置に配置して固定し、チューブとシャフトとの間に実施例２で得たシリコーンゴム組成物を５ｋｇ／ｃｍ^２で充填し、１５０℃で３０分加熱硬化し、更に２００℃で４時間ポストキュアして、アルミニウムシャフトの外周面上にシリコーンゴム層が形成され、このシリコーンゴム層の外周面上に、更にフッ素樹脂層が形成された定着ロールを得た。この定着ロールを電子写真複写機に装着してＡ４サイズの複写紙を１０万枚連続複写したが、紙しわや紙づまりなどは発生せず、また、複写された画像はすべて鮮明であった。
【００６１】
【発明の効果】
本発明の高熱伝導性シリコーンゴム組成物を硬化して得られるシリコーンゴムは、熱伝導性に優れると共に、圧縮永久歪、特に高温下での圧縮永久歪みが小さく、高温下での長期耐久性に優れており、定着ロール、特にヒートロール用の被覆材として優れたものである。[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a high heat conductive silicone rubber composition for a fixing roll, and a fixing roll using the cured product. More specifically, an addition curing method capable of obtaining a silicone rubber having a high thermal conductivity and a small compression set. The present invention relates to a silicone rubber composition of a mold and a fixing roll having a silicone rubber layer, which is a cured product of the composition, formed on the outer peripheral surface of a cored bar.
[0002]
[Prior art]
Silicone rubber has excellent electrical insulation, heat resistance, weather resistance, and flame retardancy, and has been used as a coating material for a fixing roll such as a heater roll or a pressure roll of a copying machine or a laser beam printer. In addition, a type in which a core metal is coated with a fluororesin is also used, but recently, with the speeding up of copying and the spread of color copying, the fixing roll has also been required to have low hardness, and the conventional type has been demanded. However, a type in which a core metal is coated with silicone rubber, and a fluorocarbon resin is further coated on the silicone rubber, is often used.
[0003]
Furthermore, when a rubber material is used for the heat roll, it is required to have a high thermal conductivity in order to shorten the waiting time at the time of starting up the machine or from the viewpoint of energy saving of the machine itself, and in this case, it is required to be 150 to 150 Since it is exposed to a high temperature of 200 ° C., it is required that the compression set at a high temperature is small.
[0004]
However, since silicone rubber does not have high thermal conductivity of the base rubber itself, a method of adding a filler having thermal conductivity is generally performed in order to provide high thermal conductivity. Various proposals have been made for the added silicone rubber (for example, see Patent Documents 1 to 5). These are silicone rubbers that have been used in the past, and silica, alumina, magnesium oxide, etc. are blended as thermal conductive fillers, but these thermal conductive fillers are highly filled to obtain high thermal conductivity. In this case, a fatal defect occurs as a fixing roll in which the compression set becomes large.
[0005]
In order to improve this point, a method of blending alumina having a low soda content has been proposed (see Patent Document 6). However, this method does not sufficiently satisfy the demands for a fixing roll, and furthermore, the heating loss is reduced. A method using small alumina (see Patent Literature 7) has also been proposed, but this method has not been a method capable of obtaining a sufficient effect.
[0006]
[Patent Document 1]
JP-A-58-219259
[Patent Document 2]
JP-A-3-221982
[Patent Document 3]
JP-A-10-39666
[Patent Document 4]
JP-A-11-158383
[Patent Document 5]
JP-A-2000-256558
[Patent Document 6]
JP-A-11-116806
[Patent Document 7]
JP-A-2002-72728
[0007]
[Problems to be solved by the invention]
The present invention has been made in view of the above circumstances, and has excellent thermal conductivity, small compression set, and a silicone rubber composition that provides a silicone rubber suitable as a coating material for a fixing roll, particularly a heat roll, and a silicone rubber composition. An object of the present invention is to provide a fixing roll in which a silicone rubber layer made of a cured product of a composition is formed on the outer peripheral surface of a cored bar.
[0008]
Means for Solving the Problems and Embodiments of the Invention
The present inventor has conducted intensive studies to solve the above-mentioned problems, and as a result, together with a specific liquid organopolysiloxane, a liquid organohydrogenpolysiloxane, a high thermal conductive inorganic powder and a catalyst, the following general formulas (1) to (1) The addition-curable silicone rubber composition containing the siloxane compound having the structure represented by 3) gives a silicone rubber having high thermal conductivity and small compression set, and the silicone rubber obtained by curing the composition is used as a fixing roll. The present invention was found to be suitable as a coating material, and the present invention was accomplished.
[0009]
Therefore, the present invention relates to (A) a liquid organopolysiloxane containing an alkenyl group bonded to at least two silicon atoms in one molecule and having a viscosity at 25 ° C. of 100,000 mPa · s or less: 100 parts by weight.
(B) A liquid organohydrogenpolysiloxane containing at least three hydrogen atoms bonded to silicon atoms in one molecule and having a viscosity at 25 ° C. of 1,000 mPa · s or less: 0.1 to 30 parts by weight
(C) The following general formulas (1) to (3)
Embedded image

(Where R ¹ Are the same or different unsubstituted or substituted monovalent hydrocarbon groups having 1 to 10 carbon atoms, X ¹ Is an alkoxy group or an acyloxy group having 1 to 4 carbon atoms, a is an integer of 0 to 2 and j is an integer of 0 to 100. )
Embedded image

(Where R ² Are the same or different unsubstituted or substituted monovalent hydrocarbon groups having 1 to 10 carbon atoms, X ² Is an alkoxy group or an acyloxy group having 1 to 4 carbon atoms, b is an integer of 0 to 2, and k is an integer of 0 to 100. )
Embedded image

(Where R ³ Are the same or different unsubstituted or substituted monovalent hydrocarbon groups having 1 to 10 carbon atoms, X ³ Is an alkoxy group or an acyloxy group having 1 to 4 carbon atoms, Z is an oxygen atom or a divalent hydrocarbon group having 2 to 10 carbon atoms, c is an integer of 0 to 2, n is an integer of 0 to 100, and m is It is an integer of 1 to 10. )
One or more selected from siloxane compounds represented by the formula: 0.1 to 30 parts by weight
(D) Thermally conductive inorganic powder: 50 to 1,000 parts by weight
(E) Addition reaction catalyst: amount of catalyst
A high thermal conductive silicone rubber composition for a fixing roll, and a fixing roll having a silicone rubber layer formed on an outer peripheral surface of a cored bar, wherein the silicone rubber forming the silicone rubber layer is provided. Is a product obtained by curing the silicone rubber composition.
[0010]
Hereinafter, the present invention will be described in more detail.
In the high thermal conductive silicone rubber composition for a fixing roll of the present invention, the liquid organopolysiloxane (A) has at least two alkenyl groups bonded to silicon atoms in one molecule, and has a viscosity at 25 ° C. Is 100,000 mPa · s or less, preferably 100 to 50,000 mPa · s.
[0011]
Examples of the organopolysiloxane include the following average composition formula (4)
R _d SiO _{(4-d) / 2} (4)
(In the formula, R is the same or different and is an unsubstituted or substituted monovalent hydrocarbon group having 1 to 10, preferably 1 to 8 carbon atoms, and d is 1.5 to 2.8, preferably 1. It is a positive number in the range of 8 to 2.5.)
Wherein R has at least two alkenyl groups (preferably having 2 to 8, particularly preferably 2 to 6) carbon atoms in one molecule. Examples of the alkenyl group include a vinyl group, an allyl group, a propenyl group, an isopropenyl group, a butenyl group, a hexenyl group, a cyclohexenyl group, and an octenyl group, and a vinyl group is particularly preferable.
[0012]
The content of the alkenyl group is 1.0 × 10 4 in the organopolysiloxane. ^-6 ~ 5.0 × 10 ^-3 mol / g, especially 5.0 × 10 ^-6 ~ 1.0 × 10 ^-3 mol / g is preferred. When the content of the alkenyl group is 1.0 × 10 ^-6 If the amount is less than mol / g, crosslinking may be insufficient and a gel may be formed. ^-3 If the amount is more than mol / g, the crosslinking density becomes too high, which may result in brittle rubber. The alkenyl group may be bonded to a silicon atom at the terminal of the molecular chain, to a silicon atom in the middle of the molecular chain, or to both.
[0013]
On the other hand, among the monovalent hydrocarbon groups represented by R other than the alkenyl group, methyl, ethyl, propyl, isopropyl, butyl, isobutyl, tert-butyl, pentyl, neopentyl, Hexyl group, cyclohexyl group, octyl group, nonyl group, alkyl group such as decyl group, phenyl group, tolyl group, xylyl group, aryl group such as naphthyl group, benzyl group, phenylethyl group, aralkyl group such as phenylpropyl group and Those in which part or all of the hydrogen atoms of these groups are substituted with halogen atoms such as fluorine, bromine and chlorine, cyano groups and the like, for example, chloromethyl group, chloropropyl group, bromoethyl group, trifluoropropyl group, cyanoethyl group And the like. Preferably, 90% or more of all Rs are methyl groups.
[0014]
Further, the structure of the organopolysiloxane is preferably basically one having a linear structure, but may be partially a branched structure or a cyclic structure.
[0015]
The liquid organohydrogenpolysiloxane of the component (B) contains at least three hydrogen atoms (Si—H groups) bonded to a silicon atom in one molecule, and has a viscosity at 25 ° C. of 1,000 mPa · s or less. Things. The organohydrogenpolysiloxane cures the composition by crosslinking the Si—H group in the molecule and the alkenyl group bonded to the silicon atom of the organopolysiloxane in the component (A) by a hydrosilyl addition reaction. Act as a curing agent for
[0016]
As the organohydrogenpolysiloxane of the component (B), for example, the following average composition formula (5)
R ' _e H _f SiO _{{4- (e + f)} / 2} (5)
(Wherein, R ′ is the same or different and is an unsubstituted or substituted monovalent hydrocarbon group having 1 to 10, preferably 1 to 8 carbon atoms, and e and f are e = 0.7 to 2. 1, preferably 0.8-2.0, f = 0.001-1.0, preferably 0.01-1.0, and e + f = 0.8-3.0, preferably 1.0-2. .5 is a positive number that satisfies .5)
And having at least three, preferably 3 to 100, more preferably 3 to 50 hydrogen atoms (Si-H groups) bonded to silicon atoms in one molecule.
[0017]
Here, as the monovalent hydrocarbon group for R ′, those similar to those exemplified as R in the above average composition formula (4) can be mentioned, but those having no aliphatic unsaturated group are preferable. The molecular structure of the organohydrogenpolysiloxane may be any of linear, cyclic, branched, and three-dimensional network structures, and the number of silicon atoms in one molecule (or the degree of polymerization) may be as follows. A liquid at room temperature (25 ° C.) of about 2 to 300, especially about 4 to 150 is suitably used. In addition, the hydrogen atom bonded to the silicon atom may be located at the terminal of the molecular chain, at the middle of the molecular chain, or at both positions.
[0018]
More specifically, such an organohydrogenpolysiloxane is a methylhydrogenpolysiloxane having trimethylsiloxy groups at both ends, a dimethylsiloxane / methylhydrogensiloxane copolymer having trimethylsiloxy groups at both ends, and dimethylhydrogensiloxy at both ends. Group-blocked dimethylsiloxane, dimethylhydrogensiloxy-group-blocked dimethylsiloxane-methylhydrogensiloxane copolymer at both ends, trimethylsiloxy-group-blocked methylhydrogensiloxane-diphenylsiloxane copolymer at both ends, tri-methylsiloxy-group-blocked methylhydrogen at both ends Siloxane-diphenylsiloxane-dimethylsiloxane copolymer, (CH ₃ ) ₂ HSiO _1/2 Unit and SiO _4/2 A copolymer consisting of units (CH ₃ ) ₂ HSiO _1/2 Unit and SiO _4/2 Unit and (C ₆ H ₅ ) ₃ SiO _3/2 And a copolymer composed of units.
[0019]
The amount of the organohydrogenpolysiloxane (B) is 0.1 to 30 parts by weight, preferably 0.3 to 20 parts by weight, based on 100 parts by weight of the organopolysiloxane (A). is there.
[0020]
In the silicone rubber composition of the present invention, as the component (C), the following general formulas (1) to (3)
[0021]
Embedded image

(Where R ¹ Are the same or different unsubstituted or substituted monovalent hydrocarbon groups having 1 to 10, preferably 1 to 8 carbon atoms, X ¹ Is an alkoxy group or an acyloxy group having 1 to 4 carbon atoms, a is an integer of 0 to 2, j is an integer of 0 to 100, preferably 5 to 100, more preferably 10 to 80. )
[0022]
Embedded image

(Where R ² Are the same or different unsubstituted or substituted monovalent hydrocarbon groups having 1 to 10, preferably 1 to 8 carbon atoms, X ² Is an alkoxy group or an acyloxy group having 1 to 4 carbon atoms, b is an integer of 0 to 2, k is an integer of 0 to 100, preferably 5 to 100, and more preferably 10 to 80. )
[0023]
Embedded image

(Where R ³ Are the same or different unsubstituted or substituted monovalent hydrocarbon groups having 1 to 10, preferably 1 to 8 carbon atoms, X ³ Is an alkoxy group or an acyloxy group having 1 to 4 carbon atoms, Z is an oxygen atom or a divalent hydrocarbon group having 2 to 10 carbon atoms, c is an integer of 0 to 2, n is 0 to 100, preferably 0 to 0. 80, more preferably an integer of 0 to 30, and m is an integer of 1 to 10, preferably 1 to 5. )
And at least one selected from organopolysiloxanes having a hydrolyzable group (alkoxy group or acyloxy group) bonded to a silicon atom in the molecule represented by the formula (1).
[0024]
R above ¹ , R ² , R ³ Specifically, methyl, ethyl, propyl, isopropyl, butyl, isobutyl, tert-butyl, pentyl, neopentyl, hexyl, cyclohexyl, octyl, nonyl, decyl, etc. Aryl group such as alkyl group, phenyl group, tolyl group, xylyl group, naphthyl group, aralkyl group such as benzyl group, phenylethyl group, phenylpropyl group, vinyl group, allyl group, propenyl group, isopropenyl group, butenyl group , Hexenyl group, cyclohexenyl group, alkenyl groups such as octenyl group, and those in which part or all of the hydrogen atoms of these groups are substituted with halogen atoms such as fluorine, bromine, chlorine, cyano groups, etc., for example, chloromethyl group , Chloropropyl, bromoethyl, trifluoropropyl, cyanoethyl, etc. It is below. Note that all R ¹ Is preferably a methyl group at least 50%. ² , All R ³ It is preferable that 50% or more of each is a methyl group.
[0025]
In addition, R of the siloxane compounds of the above general formulas (1) to (3) ¹ , R ² , R ³ May also include an alkenyl group. The alkenyl group preferably has 2 to 8 carbon atoms, particularly 2 to 6 carbon atoms. Examples of such an alkenyl group include a vinyl group, an allyl group, a propenyl group, an isopropenyl group, a butenyl group, and a hexenyl group. And a cyclohexenyl group and an octenyl group, with a vinyl group being particularly preferred. In this case, the content of the alkenyl group in the siloxane compound of the component (C) is 1.0 × 10 ^-2 mol / g or less, usually 0 to 1.0 × 10 ^-2 mol / g, especially 1.0 × 10 ^-6 ~ 1.0 × 10 ^-2 The amount is preferably about mol / g. The siloxane compound as the component (C) may of course not contain an alkenyl group.
[0026]
On the other hand, X in the above formula ¹ , X ² , X ³ Is an alkoxy group or an acyloxy group having 1 to 4 carbon atoms. Examples of the alkoxy group or the acyloxy group include a methoxy group, an ethoxy group, an n-propoxy group, an isopropoxy group, an n-butoxy group, and an acetoxy group. And the like. Z in the above formula is an oxygen atom or a divalent hydrocarbon group having 2 to 10 carbon atoms. Examples of the divalent hydrocarbon group include an alkylene group such as an ethylene group, a propylene group, and a butylene group. Is mentioned.
[0027]
The amount of the siloxane compound (C) is 0.1 to 30 parts by weight, preferably 1 to 20 parts by weight, based on 100 parts by weight of the organopolysiloxane (A). When the amount is less than 0.1 part by weight, the compression set is not reduced, and when the amount exceeds 30 parts by weight, the obtained rubber cured product has an adverse effect on the rubber properties as a roll coating material.
[0028]
As the thermally conductive inorganic powder of the component (D), various fillers having thermal conductivity can be used. Specific examples include quartz powder, diatomaceous earth, aluminum oxide (alumina), aluminum hydroxide, zinc oxide, silicon carbide, silicon nitride, magnesium oxide, aluminum nitride, and boron nitride. Particularly, quartz powder and alumina are preferred. Used for
[0029]
As such a thermally conductive inorganic powder, those having an average particle diameter of 0.1 to 50 μm, preferably 0.5 to 40 μm are preferably used. Particles having an average particle diameter of less than 0.1 μm are difficult to produce and may be difficult to mix in large amounts, and particles exceeding 50 μm may impair the mechanical strength of the rubber cured product. In addition, there is a possibility that a problem may occur in the surface performance of the roll. The average particle diameter can be determined as a weight average value (or median diameter) by a particle size distribution analyzer using an analysis means such as a laser light diffraction method.
[0030]
In addition, these heat conductive inorganic powders may be used alone or in combination of two or more. Further, two or more kinds of the same kind, for example, alumina, having different average particle diameters, manufacturing methods, purity, and presence or absence of surface treatment may be used in combination.
[0031]
The amount of the thermally conductive inorganic powder of the component (D) is 50 to 1,000 parts by weight, preferably 100 to 800 parts by weight, based on 100 parts by weight of the organopolysiloxane of the component (A). . If the amount is less than 50 parts by weight, high thermal conductivity cannot be obtained, and if it exceeds 1,000 parts by weight, not only the compounding becomes difficult, but also the rubber properties of the obtained cured rubber product as a roll coating material are significantly reduced. .
[0032]
These thermally conductive inorganic powders can be mixed into the composition at room temperature using a device such as a planetary mixer or a kneader. The mixing temperature may be ordinary temperature or heating, but at a high temperature of 100 to 200 ° C. before the addition of the organohydrogenpolysiloxane of the above-mentioned component (B) and the catalyst of the below-mentioned component (E). They can also be mixed.
[0033]
Examples of the addition reaction catalyst for the component (E) include platinum black, platinic chloride, chloroplatinic acid, a reaction product of chloroplatinic acid with a monovalent alcohol, a complex of chloroplatinic acid with an olefin, platinum bisacetoacetate. And platinum group metal-based catalysts such as platinum-based catalysts, palladium-based catalysts, and rhodium-based catalysts. The amount of the addition reaction catalyst is the amount of the catalyst, that is, the amount necessary for curing the composition. Usually, the amount of the metal is 0% based on the total amount of the components (A) and (B). It is preferable that it is about 0.5 to 1,000 ppm, especially about 1 to 500 ppm.
[0034]
The silicone rubber composition may contain reinforcing silica fillers such as silica hydrogel (hydrous silicic acid) and silica aerogel (silicic anhydride-fumed silica), fillers such as clay, calcium carbonate, titanium dioxide, and the like, if necessary. Heat resistance improvers such as iron, cerium oxide and iron octylate, various carbon functional silanes for improving adhesiveness and moldability, nitrogen compounds for imparting flame retardancy, and halogen compounds may be added and mixed. .
[0035]
The thermal conductivity of the cured product of the silicone rubber composition is preferably 0.5 W / (m · K) or more, more preferably 0.6 W / (m · K) or more. The upper limit is not particularly limited, but is usually 5 W / (m · K) or less.
[0036]
The fixing roll of the present invention is obtained by forming a silicone rubber layer, which is a cured product of the above silicone rubber composition, on a core (roll shaft). In this case, the material and dimensions of the core depend on the type of roll. It can be appropriately selected depending on the situation. In addition, the molding and curing methods of the silicone rubber composition can be appropriately selected. For example, the silicone rubber composition can be molded by molding methods such as injection molding, transfer molding, injection molding, and coating, and the composition can be cured by heating.
[0037]
Further, a fluororesin layer or a fluororubber layer may be further provided on the outer peripheral surface of the silicone rubber layer. In this case, the fluororesin layer can be formed of a fluororesin coating material or a fluororesin tube. In the case of using a fluorine-based resin coating material, for example, a latex of polytetrafluoroethylene resin (PTFE) or a diele latex (a fluorine-based latex manufactured by Daikin Industries, Ltd.) may be laminated on the outer peripheral surface of the silicone rubber layer. Good.
[0038]
As the fluororesin tube, a commercially available product may be used. In this case, for example, polytetrafluoroethylene resin (PTFE), tetrafluoroethylene-perfluoroalkylvinyl ether copolymer resin (PFA), and ethylene fluoride-propylene copolymer A silicone resin layer is formed by a method of using a tube of a coalescing resin (FEP), a polyvinylidene fluoride resin (PVDF), a polyvinyl fluoride resin, or the like, filling the silicone rubber composition between a cored bar and the tube, and curing the mixture. Can be formed. In addition, the thing using a PFA tube is especially preferable as the said silicone resin layer.
[0039]
On the other hand, as the fluororubber, a commercially available fluororubber tube can be used, and the fluororubber layer can be formed in the same manner as in the case of the resin tube.
[0040]
【Example】
Hereinafter, the present invention will be described specifically with reference to Examples and Comparative Examples, but the present invention is not limited to the following Examples. In the following examples, all parts are parts by weight.
[0041]
[Example 1]
100 parts of dimethylpolysiloxane (degree of polymerization: 200) both ends of which are blocked with a dimethylvinylsiloxy group as the component (A); ² / G of hydrophobized fumed silica (R-972 manufactured by Nippon Aerosil Co., Ltd.), 3 parts of a siloxane compound represented by the following general formula (I) as a component (C),
[0042]
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As a component (D), 60 parts of alumina having an average particle diameter of 4 μm and 220 parts of alumina having an average particle diameter of 15 μm were put into a planetary mixer and stirred at room temperature (23 ° C.) for 2 hours.
[0043]
The mixture was rolled on three rolls to further disperse the filler, and then returned to the planetary mixer again. As the component (B), methyl hydrogen polysiloxane having Si—H groups at both ends and side chains (polymerization degree: 17 , An Si—H group content of 0.0060 mol / g), 0.05 part of ethynylcyclohexanol as a reaction control agent, and 0.1 part of a platinum catalyst (Pt concentration 1%) as a component (E). After stirring for 15 minutes, a silicone rubber composition was obtained.
[0044]
Using this silicone rubber composition, press-curing is performed at 120 ° C. for 10 minutes, and then oven-cured at 200 ° C. for 4 hours to prepare a cured silicone rubber sample. The hardness and compression set are determined according to JIS K6301. Was measured. The thermal conductivity was measured with a thermal conductivity meter QTM-3 (manufactured by Kyoto Electronics Co., Ltd.). Table 1 shows the results.
[0045]
[Comparative Example 1]
A silicone rubber composition was obtained in the same manner as in Example 1 except that the siloxane compound represented by the general formula (I) was not added, and a cured product sample was prepared in the same manner as in Example 1, and the physical properties were measured. . Table 1 shows the results.
[0046]
[Example 2]
As the component (A), 80 parts of dimethylpolysiloxane (polymerization degree 500) having both ends blocked with a trimethylsiloxy group and having a vinyl group (vinyl group content 0.0001 mol / g) in the side chain and both ends being dimethylvinylsiloxy 20 parts of dimethylpolysiloxane (degree of polymerization 200) blocked with a group, specific surface area of 110 m as a reinforcing silica filler ² / G of hydrophobized fumed silica (R-972 manufactured by Nippon Aerosil Co., Ltd.), 5 parts of a siloxane compound represented by the following general formula (II) as a component (C),
[0047]
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As a component (D), 80 parts of quartz powder having an average particle diameter of 5 μm and 120 parts of alumina having an average particle diameter of 15 μm were put in a planetary mixer and stirred at 150 ° C. for 2 hours.
[0048]
The mixture was rolled on three rolls to further disperse the filler, and then returned to the planetary mixer again. As the component (B), methyl hydrogen polysiloxane having Si—H groups at both ends and side chains (polymerization degree: 17 , An Si-H group amount of 0.0060 mol / g), 0.05 parts of ethynylcyclohexanol as a reaction control agent, and 0.1 part of a platinum catalyst (Pt concentration: 1%) were added, followed by stirring for 15 minutes. Thus, a silicone rubber composition was obtained.
[0049]
Using this silicone rubber composition, a cured product sample was prepared in the same manner as in Example 1, and the physical properties were measured. The results are shown in Table 1.
[0050]
[Comparative Example 2]
A silicone rubber composition was obtained in the same manner as in Example 2 except that the siloxane compound represented by the general formula (II) was not added, and a cured product sample was prepared in the same manner as in Example 1, and the physical properties were measured. . Table 1 shows the results.
[0051]
[Example 3]
As the component (A), 50 parts of dimethylpolysiloxane having both ends capped with a dimethylvinylsiloxy group (degree of polymerization 200) and 50 parts of dimethylpolysiloxane having both terminals capped with a dimethylvinylsiloxy group (degree of polymerization 500), 8 parts of a siloxane compound represented by the following general formula (III) as a component (C),
[0052]
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As a component (D), 100 parts of alumina having an average particle diameter of 4 μm and 280 parts of zinc oxide having an average particle diameter of 10 μm were put in a planetary mixer and stirred at room temperature (23 ° C.) for 2 hours.
[0053]
The mixture was rolled on three rolls to further disperse the filler, and then returned to the planetary mixer again. As the component (B), methyl hydrogen polysiloxane having Si—H groups at both ends and side chains (polymerization degree: 17 5.8 parts), 0.05 part of ethynylcyclohexanol as a reaction control agent, and 0.1 part of a platinum catalyst (Pt concentration: 1%) were added, and the mixture was stirred for 15 minutes. Thus, a silicone rubber composition was obtained.
[0054]
Using this silicone rubber composition, a cured product sample was prepared in the same manner as in Example 1, and the physical properties were measured. The results are shown in Table 1.
[0055]
[Comparative Example 3]
A silicone rubber composition was obtained in the same manner as in Example 3 except that the siloxane compound represented by the general formula (III) was not added, and a cured product sample was prepared in the same manner as in Example 1, and the physical properties were measured. . Table 1 shows the results.
[0056]
[Table 1]

Compression set measurement conditions: 180 ° C x 22 hours, 25% compression
[0057]
[Example 4]
On the surface, primer No. 1 for addition reaction type liquid silicone rubber was used. An aluminum shaft having a diameter of 10 mm and a length of 300 mm coated with 101A / B (manufactured by Shin-Etsu Chemical Co., Ltd.) was fixed in a mold, and the silicone rubber composition obtained in Example 1 was placed in the mold at 10 kg / cm. ² And cured by heating at 150 ° C. for 30 minutes, and further post-cured at 200 ° C. for 4 hours to obtain a fixing roll having a silicone rubber layer having an outer diameter of 20 mm and a length of 250 mm formed on the outer peripheral surface of an aluminum shaft. Was. The fixing roll was mounted on an electrophotographic copying machine and 100,000 sheets of A4 size copy paper were continuously copied. However, no wrinkles or paper jams occurred, and all the copied images were clear.
[0058]
[Comparative Example 4]
A fixing roll was obtained in the same manner as in Example 4 except that the silicone rubber composition obtained in Comparative Example 1 was used, and this fixing roll was attached to an electrophotographic copying machine to continuously copy A4 size copy paper. However, when the number of sheets exceeded about 80,000 sheets, paper wrinkles and paper jams occurred.
[0059]
[Comparative Example 5]
A fixing roll was obtained in the same manner as in Example 4 except that the silicone rubber composition obtained in Comparative Example 2 was used, and this fixing roll was mounted on an electrophotographic copying machine to continuously copy A4 size copy paper. However, when the number of sheets exceeded about 70,000 sheets, paper wrinkles and paper jams occurred.
[0060]
[Example 5]
On the inner surface, a primer No. for addition reaction type liquid silicone rubber was used. An aluminum shaft with a diameter of 10 mm and a length of 300 mm coated with the above primer on the inside of a PFA resin tube having an outer diameter of 20 mm, a length of 250 mm and a thickness of 50 μm coated with 101A / B (manufactured by Shin-Etsu Chemical Co., Ltd.) Is fixed at a position equidistant from the inner surface of the tube, and the silicone rubber composition obtained in Example 2 is placed between the tube and the shaft at 5 kg / cm. ² And cured by heating at 150 ° C. for 30 minutes, and further post-cured at 200 ° C. for 4 hours to form a silicone rubber layer on the outer peripheral surface of the aluminum shaft. A fixing roll on which a resin layer was formed was obtained. The fixing roll was mounted on an electrophotographic copying machine and 100,000 sheets of A4 size copy paper were continuously copied. However, no wrinkles or paper jams occurred, and all the copied images were clear.
[0061]
【The invention's effect】
The silicone rubber obtained by curing the high thermal conductive silicone rubber composition of the present invention has excellent thermal conductivity and low compression set, especially low compression set at high temperatures, and has long-term durability at high temperatures. It is excellent and is excellent as a coating material for a fixing roll, particularly for a heat roll.

Claims (5)

(A) A liquid organopolysiloxane containing at least two alkenyl groups bonded to two silicon atoms in one molecule and having a viscosity at 25 ° C. of 100,000 mPa · s or less: 100 parts by weight (B) Liquid organohydrogenpolysiloxane containing at least three hydrogen atoms bonded to silicon atoms and having a viscosity at 25 ° C. of 1,000 mPa · s or less: 0.1 to 30 parts by weight (C) 1)-(3)

(Wherein, R ¹ is the same or different, unsubstituted or substituted monovalent hydrocarbon group having 1 to 10 carbon atoms, X ¹ is an alkoxy group or acyloxy group having 1 to 4 carbon atoms, a is 0 to 2 Integer, j is an integer of 0 to 100.)

(Wherein, R ² is the same or different, unsubstituted or substituted monovalent hydrocarbon group having 1 to 10 carbon atoms, X ² is an alkoxy group or acyloxy group having 1 to 4 carbon atoms, b is 0 to 2 Integer, k is an integer of 0 to 100.)

(Wherein, R ³ is the same or different, unsubstituted or substituted monovalent hydrocarbon group having 1 to 10 carbon atoms, X ³ is an alkoxy group or acyloxy group having 1 to 4 carbon atoms, Z is an oxygen atom or a carbon atom. A divalent hydrocarbon group having 2 to 10 atoms, c is an integer of 0 to 2, n is an integer of 0 to 100, and m is an integer of 1 to 10.)
One or more selected from siloxane compounds represented by the formula: 0.1 to 30 parts by weight (D) Thermally conductive inorganic powder: 50 to 1,000 parts by weight (E) Addition reaction catalyst: contains catalyst amount A highly heat-conductive silicone rubber composition for a fixing roll, characterized in that: The high thermal conductive silicone rubber composition for a fixing roll according to claim 1, wherein the thermal conductive inorganic powder is quartz powder or alumina. The silicone rubber composition according to claim 1, wherein the thermal conductivity of the cured product is 0.5 W / (m · K) or more. A fixing roll having a silicone rubber layer formed on an outer peripheral surface of a cored bar, wherein the silicone rubber forming the silicone rubber layer cures the silicone rubber composition according to any one of claims 1 to 3. A fixing roll, comprising: The fixing roll according to claim 4, further comprising a fluororesin layer or a fluororubber layer on the outer peripheral surface of the silicone rubber layer.