JP2004195756A

JP2004195756A - Mold for optical disk substrate

Info

Publication number: JP2004195756A
Application number: JP2002365783A
Authority: JP
Inventors: Kazuo Inoue; 和夫井上
Original assignee: Matsushita Electric Industrial Co Ltd
Current assignee: Panasonic Holdings Corp
Priority date: 2002-12-17
Filing date: 2002-12-17
Publication date: 2004-07-15

Abstract

<P>PROBLEM TO BE SOLVED: To provide a mold for an optical disk substrate enhancing transfer properties, strong against an impact and having sufficient strength. <P>SOLUTION: At least a part of the surface of the cavity (20) of a pair of fitted molds (1 and 2) at least one of which is provided with a stamper (3)or the rear surface of the stamper (3) is formed of a low heat conductive metal member of which the heat conductivity is 2/3 or less that of a member for forming another cavity surface other than the stamper, the tensile strength is 300 MPa or more and the melting point is 400°C or higher. The low heat conductive metal member preferably comprises a metal mainly comprising titanium and containing aluminum or vanadium. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

【０００１】
【発明の属する技術分野】
本発明は、スタンパに形成した凹凸を転写させる光ディスク基板用金型に関する。
【０００２】
【従来の技術】
従来の金型としては、金型のコアの成形面にシートを介してスタンパを取り付けてキャビティ内圧が十分伝達されるまでは射出された溶融樹脂の熱が奪われないようにして成形基板の複屈折と転写性を向上させることが開示されている（例えば特許文献１参照）。材質としては、アルミニウムまたは銅、あるいは合成樹脂（例えば特許文献１）やセラミック（例えば特許文献２参照）がある。
【０００３】
図１に従来の金型の断面図を示す。金型は固定金型１と可動金型２の嵌合する１つから構成される。ここでは、情報の凹凸を形成したスタンパ３を固定金型１に装着する場合を示す。
【０００４】
固定金型１には中央部に溶融樹脂が流入するスプル部を持つスプルブッシュ４がある。スプルブッシュ４の周りにはスタンパホルダー５があり、スタンパ３の内側を保持している。スタンパ３の外周側には外周リング７があってスタンパ３の外側を保持している。スタンパ３の裏面には断熱材８があり、この断熱材８はスタンパ３と共に先のスタンパホルダー５と外周リング７によって固定側鏡面盤６に装着される。
【０００５】
ここで、断熱材８はスタンパ３からの熱の伝導を遅らせる働きをする。固定側鏡面盤６は固定側基盤９に取り付けられている。固定側鏡面盤６の外周側には固定側突き当てリング１７がある。
【０００６】
可動金型２は、内側から、エジェクタピン１０、カットパンチ１１、エジェクタスリーブ１２、可動側固定ブッシュ１３、可動側鏡面盤１４がある。可動側鏡面盤１４は可動側基盤１５に取り付けられている。
【０００７】
可動金型２の最外周には可動側突き当てリング１６があり、可動側基盤１５に取り付けられており、固定側基盤９に取り付けられた固定側突き当てリング１７と突き当たることで位置出しを行う。
【０００８】
従来の金型でスタンパ以外の箇所に低熱伝導部材を設けた金型としては、キャビティ表面にセラミックまたは合成樹脂を設けることでヒケをなくして表面光沢や微細な凹凸を転写することが開示されている（例えば特許文献３参照）。また、キャビティの周端部を形成する環状部材にセラミックを用いて基板周端部にヒケや反りの発生しない基板を提供することが開示されている（例えば特許文献４参照）
【０００９】
【特許文献１】
特開昭６２−００５８２４号公報
【００１０】
【特許文献２】
特開平０５−０３８７２１号公報
【００１１】
【特許文献３】
特開平０６−２１８７６９号公報
【００１２】
【特許文献４】
特開昭６３−０７４６１８号公報
【００１３】
【発明が解決しようとする課題】
射出成形では金型内に溶融樹脂を流入させるためキャビティ表面の部材は急激な温度の上昇や下降が生じる。また、金型を閉じた後に型締力を発生させてスタンパ上の凹凸を転写させるので金型部材は衝撃を受ける。
【００１４】
これに対してスタンパと鏡面盤との間、もしくはキャビティ表面に断熱材を用いているが、断熱材の材料としてセラミックを用いると脆くて衝撃に弱く割れやすい。また、合成樹脂は熱可塑性樹脂では軟らかく、熱硬化性樹脂では脆くて衝撃に弱い。金属としてアルミニウムや銅が特許文献１に開示されているが、これらの材料の場合は軟らかく強度が弱いという問題がある。
【００１５】
本発明は、前記従来の問題を解決するため、衝撃に強く強度が十分な断熱材を用いた光ディスク基板用金型を提供することを目的とする。
【００１６】
【課題を解決するための手段】
前記目的を達成するため、本発明の第１番目の光ディスク基板用金型は、少なくとも一方にスタンパを装着した一対の嵌合する金型であって、キャビティ表面の少なくとも一部を形成する部材を、熱伝導率がスタンパ以外の他のキャビティ表面を形成する部材の２／３以下、引張強度が３００ＭＰａ以上、融点が４００℃以上の低熱伝導金属部材で形成することを特徴とする。
【００１７】
本発明の第２番目の光ディスク基板用金型は、少なくとも一方にスタンパを装着した一対の嵌合する金型であって、キャビティ表面の少なくとも一部を形成する部材を、熱伝導率が１３Ｗ／ｍＫ以下、引張強度が３００ＭＰａ以上、融点が４００℃以上の低熱伝導金属部材で形成することを特徴とする。
【００１８】
本発明の第３番目の光ディスク基板用金型は、少なくとも一方にスタンパを装着した一対の嵌合する金型であって、前記スタンパと前記スタンパを装着する側の温度調整用媒体を流した鏡面部材との間に、熱伝導率が前記鏡面部材の３／４以下、引張強度が３００ＭＰａ以上、融点が４００℃以上の低熱伝導金属部材を配設することを特徴とする。
【００１９】
本発明の第４番目の光ディスク基板用金型は、少なくとも一方にスタンパを装着した一対の嵌合する金型であって、スタンパと金型表面との間に熱伝導率が１５Ｗ／ｍＫ以下である低熱伝導金属部材を配設することを特徴とする。
【００２０】
【発明の実施の形態】
本発明は、衝撃に強く強度が十分な断熱材を用いた光ディスク基板用金型である。このため、キャビティ表面の少なくとも一部を形成する部材を低熱伝導金属部材とする。前記低熱伝導金属部材としては、チタンを主成分とする材料が好ましい。ここで「主成分」とは、７０重量％以上をいう。
【００２１】
また、前記低熱伝導金属材料は、アルミニウムまたはバナジウムを含有することが好ましい。好ましい含有量は、２〜７重量％の範囲である。
【００２２】
前記低熱伝導金属部材の厚みは、０．５ｍｍ以上３ｍｍ以下の範囲が好ましい。また、前記低熱伝導金属部材のキャビティ表面の粗さを０．４Ｓ以下とすることが好ましい。
【００２３】
また、低熱伝導金属部材のキャビティ側面の粗さを０．１Ｓ以下とすることが好ましい。
【００２４】
また、低熱伝導金属部材のスタンパとの接触面の粗さを０．４Ｓ以下とすることが好ましい。
【００２５】
本発明の具体的実施の形態について、以下に図を用いて詳細に説明する。
【００２６】
（実施の形態１）
本発明の実施の形態１に用いる光ディスク基板用金型の構成は、図１に示した従来の断熱構造と同じである。金型は固定金型１と可動金型２とからなる。スタンパ３は固定金型１に装着している。
【００２７】
固定金型１には中央部に溶融樹脂が流入するスプル部を持つスプルブッシュ４がある。スプルブッシュ４の周りにはスタンパホルダー５があり、スタンパ３の内側を保持している。スタンパ３の外周側には外周リング７があってスタンパ３の外側を保持している。スタンパ３の裏面には断熱材８があり、この断熱材８はスタンパ３と共に先のスタンパホルダー５と外周リング７によって固定側鏡面盤６に装着される。固定側鏡面盤６には温度調整用の流体を流す溝が設けられていて、固定側基盤９に取り付けられている。また、固定側鏡面盤６の外周側には固定側突き当てリング１７がある。
【００２８】
可動金型２は、内側から、エジェクタピン１０、カットパンチ１１、エジェクタスリーブ１２、可動側固定ブッシュ１３、可動側鏡面盤１４がある。カットパンチ１１は成形品に内孔を形成するためのものである。エジェクタピン１０とエジェクタスリーブ１２は成形品を金型から取り出す際に、それぞれ、スプルと成形品とを押し出す働きをする。可動側鏡面盤１４にも固定側鏡面盤６と同様に温度調整用の流体を流す溝が設けられていて、可動側基盤１５に取り付けられている。２０はキャビティである。
【００２９】
可動金型２の最外周には可動側突き当てリング１６があり、可動側基盤１５に取り付けられている。この可動側突き当てリング１６は、固定側基盤９に取り付けられた固定側突き当てリング１７と突き当たることで位置出しを行う。
【００３０】
光ディスク基板用金型の材料は錆ないようにステンレス鋼からできている場合が多い。この場合の熱伝導率は２０〜２５Ｗ／ｍＫである。スタンパ３はニッケルからできており、熱伝導率は約９０Ｗ／ｍＫである。断熱材８としてはステンレス鋼より低い熱伝導率の金属としてチタン合金を選んだ。チタン合金としては主成分（７０重量％以上）がチタンで、アルミニウムやバナジウムを含む（２〜７重量％）ものが薄板に仕上げやすい。熱伝導率は７〜１２Ｗ／ｍＫである。
【００３１】
断熱材８の厚さは他の金型部材同様用に精度が必要である。特に面内ばらつきを抑制するために平行度も重要である。しかし、０．５ｍｍより薄いと、厚み精度や平行度などの機械加工精度を出しにくい。このため０．５ｍｍより厚く作製するのが好ましい。また、転写に必要な金型温度と断熱材の厚みとの関係を調べるためにシミュレーションでスタンパの到達温度がポリカーボネート樹脂のガラス転移温度より高い１５０℃ないし１６０℃になる金型温度を計算した結果、厚さが２ｍｍ以上になるとスタンパがこの特定の到達温度になる場合の金型温度がほぼ飽和する。したがって、断熱板の厚みは２ｍｍ以下が好ましく、さらに好ましくは３ｍｍ以下もあれば十分である。そこで、断熱材の厚さは０．５ｍｍ以上３ｍｍ以下が好適である。
【００３２】
断熱材を熱伝導率１０Ｗ／ｍＫ、厚み２ｍｍのチタン合金で作製し、他の部材をステンレス鋼で作製した。スタンパにはピットが形成されており、形状はトラックピッチ０．２０μｍ、ピットピッチ０．２４μｍ、ピット長８０〜１６０ｎｍ、深さ６５ｎｍのものを用いた。
【００３３】
直径１２０ｍｍ、厚さ１．１ｍｍの基板をポリカーボネート樹脂で作製した。最大射出速度２５０ｍｍ／ｓ、最大型締め力３０トン、成形サイクル１０秒で射出成形した。
【００３４】
半径５８ｍｍで十分な転写が得られる金型温度は、断熱材８がある時が７０℃以上であるのに対して、断熱材８がない通常の場合が９０℃以上であり、転写する下限の金型温度は下がった。
【００３５】
金型内に流入する樹脂の粘度を下げて流れやすくするため樹脂は最高で４００℃近傍まで加熱される。金型内のキャビティ面はこの溶融した樹脂で加熱され、最高で２００℃近傍まで温度が上昇する。そこで、金型部材の融点は形状を安定して維持する上で４００℃以上は必要である。チタン合金の融点は約１６００℃である。
【００３６】
また、機械的衝撃や型締力に耐える安定な形状を維持するには、引張強度が３００ＭＰａ以上必要である。チタン合金の引張強度は８００ＭＰａ以上である。金型が断熱材８以外はステンレス鋼からなる場合に、シミュレーションで断熱材８の熱伝導率を変えて転写下限の金型温度を求めると、通常の全部がステンレス鋼からなる場合の転写下限の金型温度より１０Ｋ以上低い金型温度で転写するのは断熱材の熱伝導率が１５Ｗ／ｍＫ以下の場合であった。
【００３７】
上記の金型は部材の殆どがステンレス鋼でできている場合であるが、金型は炭素鋼等の他の鋼鉄でもアルミニウム合金でも作製できる。この場合、転写下限の金型温度は断熱材８と他の部材との熱伝導率の比で決まる。そこで、断熱材８の厚みを２ｍｍに固定してシミュレーションで断熱材の熱伝導率を変えて転写下限の金型温度を求めた。すると、通常の全部が同一材からなる場合の転写下限の金型温度より１０Ｋ以上低い金型温度で転写するのは断熱材８の熱伝導率が断熱材８以外の部材の熱伝導率の３／４倍以下の場合であった。
【００３８】
例えば、断熱材８以外がアルミニウム合金で断熱材８がニッケル、鋼鉄、黄銅、青銅、ステンレス鋼等がある。
【００３９】
これまでは断熱材８以外の金型部材が全て同じ材料の場合を取扱ったが、断熱材８と接しており温調されている固定側鏡面盤６の材料の熱伝導率が支配的であった。すなわち、断熱材８の熱伝導率が断熱材８に接する固定側鏡面盤６の熱伝導率の３／４倍以下の場合に断熱材８がない場合に比べて転写下限の金型温度は１０Ｋ以上下がった。
【００４０】
同様に、断熱材８の熱伝導率が１５Ｗ／ｍＫ以下であり断熱材８の下の固定側鏡面盤６がステンレス鋼でできている場合は断熱材８がない場合に比べて転写下限の金型温度は１０Ｋ以上下がった。
【００４１】
本発明の金型では断熱材８がスタンパ３の最高到達温度より十分高い融点を持ち、セラミックに比べて延性があって、剛性も十分ある金属であるため、成形中に断熱材が破損することはなく、金型強度は十分であった。
【００４２】
次に断熱材８の表面粗さについて調べた。スタンパ３の厚さは０．３ｍｍほどであるため断熱材８の表面に傷や凹凸等があると成形した基板に転写される。表面粗さが最大粗さで０．４μｍ以下であれば鏡面スタンパを用いて成形した場合に成形基板の表面粗さは一定で変わらないことから、この表面粗さの範囲であれば成形基板にスタンパ３を通して転写されない。
【００４３】
実施の形態１ではスタンパ３を固定金型１側に装着する場合について示したが、スタンパ３は可動金型２の方に装着しても良いし、固定金型１と可動金型２の両方に装着しても良い。同様に、断熱材８も固定金型１側でなく、可動金型２側に装着されたスタンパ３の裏側に設けても構わない。
【００４４】
（実施の形態２）
本発明の実施の形態２に用いる光ディスク基板用金型の構成を図２に示す。図１と比べて図２ではスタンパ３の裏面に断熱材８はなく、スタンパ３を装着したのとは反対側、すなわち、ここでは可動金型２側で、可動側鏡面盤１４のキャビティ側の面に断熱材１８を設けている。この断熱材１８は着脱の必要がないため、可動側鏡面盤１４と溶着している。
【００４５】
この場合は、転写にかかわるスタンパ３の熱伝導には直接は働かないが、金型内に流入した溶融樹脂の冷却が遅れるため溶融樹脂によってスタンパ３が温められる時間が長くなり転写が良化する。
【００４６】
実施の形態２でも断熱材１８の厚さは他の金型部材同様用に精度が必要である。特に面内ばらつきを抑制するために平行度も重要である。しかし、０．５ｍｍより薄いと厚み精度や平行度などの機械加工精度を出しにくい。このため０．５ｍｍより厚く作製する必要がある。また、金型温度と断熱材の厚みとの関係を調べるためにシミュレーションで金型温度を一定にして断熱材の到達温度を計算した結果、厚さが２ｍｍ以上になると断熱材の到達温度がほぼ飽和する。したがって、断熱板の厚みは２ｍｍ以下、好ましくは３ｍｍ以下もあれば十分である。そこで、断熱材の厚さは０．５ｍｍ以上３ｍｍ以下が好適である。
【００４７】
断熱材１８を熱伝導率１０Ｗ／ｍＫ、厚み２ｍｍのチタン合金で作製し、他の部材をステンレス鋼で作製した。スタンパにはピットが形成されており、形状はトラックピッチ０．２０μｍ、ピットピッチ０．２４μｍ、ピット長８０〜１６０ｎｍ、深さ６５ｎｍのものを用いた。
【００４８】
直径１２０ｍｍ、厚さ１．１ｍｍの基板をポリカーボネート樹脂で作製した。最大射出速度２５０ｍｍ／ｓ、最大型締め力３０トン、成形サイクル１０秒で射出成形した。
【００４９】
半径５８ｍｍで十分な転写が得られる金型温度は、断熱材１８がない通常の場合が９０℃以上であり、断熱材１８がある時が７５℃以上であった。
【００５０】
金型内に流入する樹脂の粘度を下げて流れやすくするため樹脂は最高で４００℃近傍まで加熱される。金型内のキャビティ面はこの溶融した樹脂で加熱され、最高で２００℃近傍まで温度が上昇する。そこで、金型部材の融点は形状を安定して維持する上で４００℃以上は必要である。
【００５１】
また、機械的衝撃や型締力に耐ええる安定な形状を維持するには引張強度が３００ＭＰａ以上必要である。
【００５２】
金型が断熱材１８以外はステンレス鋼からなる場合に、シミュレーションで断熱材１８の熱伝導率を変えて転写下限の金型温度を求めると、通常の全部がステンレス鋼からなる場合の転写下限の金型温度より１０Ｋ低い金型温度で転写するのは断熱材１８の熱伝導率が１３Ｗ／ｍＫ以下の場合であった。
【００５３】
上記の金型は部材の殆どがステンレス鋼でできている場合であるが、金型は炭素鋼等の他の鋼鉄でもアルミニウム合金でも作製できる。この場合も転写下限の金型温度は断熱材１８と他の部材との熱伝導率の比で決まる。そこで、断熱材１８の熱伝導率を変えて転写下限の金型温度を求めると、通常の全部が同一材からなる場合の転写下限の金型温度より１０Ｋ以上低い金型温度で転写するのは断熱材１８の熱伝導率が断熱材１８以外の部材の熱伝導率の２／３倍以下の場合であった。
【００５４】
例えば、断熱材１８以外がアルミニウム合金で断熱材１８がニッケル、鋼鉄、黄銅、青銅、ステンレス鋼等がある。
【００５５】
これまでは断熱材１８以外の金型部材が全て同じ材料の場合を取扱ったが、断熱材１８と同様にキャビティ近傍の部材、特に温調されている可動側鏡面盤１４の材料の熱伝導率が支配的であった。すなわち、断熱材１８の熱伝導率が断熱材１８の下の可動側鏡面盤１４の熱伝導率の２／３倍以下の場合に断熱材１８がない場合に比べて転写下限の金型温度は１０Ｋ以上下がった。
【００５６】
同様に、断熱材１８の熱伝導率が１３Ｗ／ｍＫ以下であり断熱材１８の下の可動側鏡面盤１４がステンレス鋼でできている場合は断熱材１８がない場合に比べて転写下限の金型温度は１０Ｋ以上下がった。
【００５７】
本発明の金型では断熱材１８がスタンパ３の最高到達温度より十分高い融点を持ち、セラミックに比べて延性があって、剛性も十分ある金属であるため、成形中に断熱材１８が破損することはなく、金型強度は十分であった。
【００５８】
次に断熱材１８の表面状態であるが、断熱材１８の表面に傷や凹凸等があると成形した基板に転写される。そこで、断熱材１８がある側が光ディスクの再生面側になる場合は断熱材１８の表面粗さは、最大粗さで０．１μｍ以下が好ましかった。
【００５９】
実施の形態２では断熱材１８は可動側鏡面部材１４のキャビティ表面に用いたが、スタンパ３が可動金型２に装着する場合は、もちろん、固定側鏡面盤６のキャビティ表面に用いればよい。ここでは可動側鏡面盤１４と断熱材１８とを溶着したが、もちろん、他の手段で固定しても良い。さらに、実施の形態２を実施の形態１に加えた金型構造でも良い。
【００６０】
（実施の形態３）
本発明の実施の形態３に用いる光ディスク基板用金型の構成を図３に示す。図１と比べて図３ではスタンパ３の裏面に断熱材８はなく、外周リングを断熱材１９と外周リング７から形成している。
【００６１】
この断熱材１９は着脱の必要がないため、外周リング７と溶着している。この場合は、転写にかかわるスタンパ３の熱伝導には直接は働かないが、金型内に流入した溶融樹脂の冷却が遅れるため溶融樹脂によってスタンパ３が温められる時間が長くなり転写が良化する。
【００６２】
実施の形態３でも断熱材１９の厚さは他の金型部材同様用に精度が必要である。しかし、０．５ｍｍより薄いと厚み精度や平行度などの機械加工精度を出しにくい。このため０．５ｍｍより厚く作製することが好ましい。また、金型温度と断熱材１９の厚みとの関係を調べるためにシミュレーションで金型温度を一定にして断熱材１９の到達温度を計算した結果、厚さが２ｍｍ以上になると断熱材１９の到達温度がほぼ飽和した。
【００６３】
断熱材１９を熱伝導率１０Ｗ／ｍＫ、厚み２ｍｍのチタン合金で作製し、他の部材をステンレス鋼で作製した。スタンパ３にはピットが形成されており、形状はトラックピッチ０．２０μｍ、ピットピッチ０．２４μｍ、ピット長８０〜１６０ｎｍ、深さ６５ｎｍのものを用いた。
【００６４】
直径１２０ｍｍ、厚さ１．１ｍｍの基板をポリカーボネート樹脂で作製した。最大射出速度２５０ｍｍ／ｓ、最大型締め力３０トン、成形サイクル１０秒で射出成形した。半径５８ｍｍで十分な転写が得られる金型温度は、断熱材１９がない通常の場合が９０℃以上であり、断熱材１９がある時が７５℃以上であった。
【００６５】
金型内に流入する樹脂の粘度を下げて流れやすくするため樹脂は最高で４００℃近傍まで加熱される。金型内のキャビティ面はこの溶融した樹脂で加熱され、最高で２００℃近傍まで温度が上昇する。そこで、金型部材の融点は形状を安定して維持する上で４００℃以上は必要である。
【００６６】
また、機械的衝撃や型締力に耐ええる安定な形状を維持するには引張強度が３００ＭＰａ以上必要である。
【００６７】
金型が断熱材１９以外はステンレス鋼からなる場合に、シミュレーションで断熱材１９の熱伝導率を変えて転写下限の金型温度を求めると、通常の全部がステンレス鋼からなる場合の転写下限の金型温度より１０Ｋ低い金型温度で転写するのは断熱材１９の熱伝導率が１３Ｗ／ｍＫ以下の場合であった。
【００６８】
上記の金型は部材の殆どがステンレス鋼でできている場合であるが、金型は炭素鋼等の他の鋼鉄でもアルミニウム合金でも作製できる。この場合も転写下限の金型温度は断熱材１９と他の部材との熱伝導率の比で決まる。そこで、断熱材１９の厚さを２ｍｍに固定して断熱材１９の熱伝導率を変えて転写下限の金型温度を求めると、通常の全部が同一材からなる場合の転写下限の金型温度より１０Ｋ以上低い金型温度で転写するのは断熱材１９の熱伝導率が断熱材１９以外の部材の熱伝導率の２／３倍以下の場合であった。
【００６９】
例えば、断熱材１９以外がアルミニウム合金で断熱材１９がニッケル、鋼鉄、黄銅、青銅、ステンレス鋼等がある。
【００７０】
これまでは断熱材１９以外の金型部材を全て同じ材料としたが、断熱材１９と同様にキャビティ近傍の部材、特に温調されている可動側鏡面盤１４の材料の熱伝導率が支配的であった。すなわち、断熱材１９の熱伝導率が断熱材１９と接する可動側鏡面盤１４の熱伝導率の２／３倍以下の場合に断熱材１９がない場合に比べて転写下限の金型温度は１０Ｋ以上下がった。
【００７１】
同様に、断熱材１９の熱伝導率が１３Ｗ／ｍＫ以下であり、断熱材１９の下の可動側鏡面盤１４がステンレス鋼でできている場合は、断熱材１９がない場合に比べて転写下限の金型温度は１０Ｋ以上下がった。
【００７２】
本実施形態の金型では断熱材１９がスタンパの最高到達温度より十分高い融点を持ち、セラミックに比べて延性があって、剛性も十分ある金属であるため、成形中に断熱材が破損することはなく、金型強度は十分であった。
【００７３】
次に断熱材１９の表面状態は、断熱材１９の表面に傷や凹凸等があると成形した基板に転写される。また、断熱材１９は可動側鏡面盤１４と摺動する。そこで、断熱材１９の表面粗さは最大粗さで０．４μｍ以下が好ましかった。
【００７４】
本発明の実施の形態３では従来の外周リングが外周リング７と断熱材１９とで構成されていたが、もちろん断熱材１９だけで外周リング７を構成しても良い。
【００７５】
本発明の実施の形態３に実施の形態１や実施の形態２を加えても良い。
【００７６】
実施の形態２では断熱材１８を可動側鏡面盤１４のキャビティ表面に用いたが、もちろん、エジェクタピン１０、カットパンチ１１、エジェクタスリーブ１２、可動側固定ブッシュ１３、スプルブッシュ４、スタンパホルダー５の表面に用いても良いし、それ自体を断熱材で作製しても良い。
【００７７】
【発明の効果】
本発明により、金型温度が低くても成形基板の転写が得られ、かつ、衝撃に強く強度が十分な光ディスク基板用金型が得られる。したがって、高密度スタンパを用いた成形が可能になる。
【図面の簡単な説明】
【図１】本発明の実施の形態１および従来例に用いる金型の構成を示す概略断面図
【図２】本発明の実施の形態２の構成を示す概略断面図
【図３】本発明の実施の形態３の構成を示す概略断面図
【符号の説明】
１固定金型
２可動金型
３スタンパ
４スプルブッシュ
５スタンパホルダー
６固定側鏡面盤
７外周リング
８，１８，１９断熱材
９固定側基盤
１０エジェクタピン
１１カットパンチ
１２エジェクタスリーブ
１３可動側固定ブッシュ
１４可動側鏡面盤
１５可動側基盤
１６可動側突き当てリング
１７固定側突き当てリング
２０キャビティ[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a mold for an optical disk substrate that transfers irregularities formed on a stamper.
[0002]
[Prior art]
In a conventional mold, a stamper is attached to a molding surface of a mold core via a sheet so that the heat of the injected molten resin is not taken away until the internal pressure of the cavity is sufficiently transmitted. It is disclosed that refraction and transferability are improved (for example, see Patent Document 1). Examples of the material include aluminum or copper, a synthetic resin (for example, Patent Document 1), and a ceramic (for example, see Patent Document 2).
[0003]
FIG. 1 shows a sectional view of a conventional mold. The mold includes one in which the fixed mold 1 and the movable mold 2 are fitted. Here, a case is shown in which the stamper 3 having the information unevenness is mounted on the fixed mold 1.
[0004]
The stationary mold 1 has a sprue bush 4 having a sprue portion into which a molten resin flows into a central portion. A stamper holder 5 is provided around the sprue bush 4 and holds the inside of the stamper 3. An outer peripheral ring 7 is provided on the outer peripheral side of the stamper 3 to hold the outside of the stamper 3. A heat insulating material 8 is provided on the back surface of the stamper 3, and the heat insulating material 8 is mounted on the fixed mirror plate 6 together with the stamper 3 by the stamper holder 5 and the outer peripheral ring 7.
[0005]
Here, the heat insulating material 8 functions to delay the conduction of heat from the stamper 3. The fixed mirror panel 6 is mounted on a fixed base 9. A fixed-side butting ring 17 is provided on the outer peripheral side of the fixed-side mirror panel 6.
[0006]
The movable mold 2 includes an ejector pin 10, a cut punch 11, an ejector sleeve 12, a movable-side fixed bush 13, and a movable-side mirror plate 14 from the inside. The movable mirror 14 is attached to a movable base 15.
[0007]
A movable abutting ring 16 is provided on the outermost periphery of the movable mold 2, is attached to the movable base 15, and is positioned by abutting against a fixed abutting ring 17 attached to the fixed base 9. .
[0008]
As a mold provided with a low heat conductive member at a place other than the stamper in a conventional mold, it is disclosed that surface gloss and fine irregularities are transferred by eliminating ceramic sinks by providing ceramic or synthetic resin on the cavity surface. (For example, see Patent Document 3). Further, it is disclosed that a ceramic is used for an annular member forming a peripheral end of a cavity to provide a substrate free from sink marks and warpage at the peripheral end of the substrate (for example, see Patent Document 4).
[0009]
[Patent Document 1]
Japanese Patent Application Laid-Open No. Sho 62-005824
[Patent Document 2]
Japanese Patent Application Laid-Open No. 05-038721
[Patent Document 3]
Japanese Patent Application Laid-Open No. 06-218768
[Patent Document 4]
JP-A-63-074618
[Problems to be solved by the invention]
In the injection molding, the temperature of the members on the surface of the cavity rapidly rises and falls because the molten resin flows into the mold. Further, after the mold is closed, a mold clamping force is generated to transfer the irregularities on the stamper, so that the mold member receives an impact.
[0014]
On the other hand, a heat insulating material is used between the stamper and the mirror-finished surface or on the cavity surface. However, if ceramic is used as the heat insulating material, it is brittle, weak to impact, and easily broken. The synthetic resin is soft as a thermoplastic resin, and brittle as a thermosetting resin and is vulnerable to impact. Patent Literature 1 discloses aluminum and copper as metals, but these materials have a problem that they are soft and have low strength.
[0015]
SUMMARY OF THE INVENTION An object of the present invention is to provide a mold for an optical disk substrate using a heat-insulating material that is strong against impact and has sufficient strength in order to solve the conventional problem.
[0016]
[Means for Solving the Problems]
In order to achieve the above object, a first mold for an optical disk substrate of the present invention is a pair of fitting molds each having a stamper mounted on at least one side thereof, and a member forming at least a part of a cavity surface. It is characterized by being formed of a low heat conductive metal member having a thermal conductivity of 2/3 or less of the member forming the cavity surface other than the stamper, a tensile strength of 300 MPa or more, and a melting point of 400 ° C. or more.
[0017]
A second mold for an optical disk substrate according to the present invention is a pair of fitting molds each having a stamper mounted on at least one of the molds, and a member forming at least a part of the cavity surface has a thermal conductivity of 13 W / It is characterized by being formed of a low heat conductive metal member having a mK or less, a tensile strength of 300 MPa or more, and a melting point of 400 ° C. or more.
[0018]
A third optical disk substrate mold according to the present invention is a pair of fitting molds each having a stamper mounted on at least one of the molds, and has a mirror surface on which the stamper and the temperature adjusting medium on the side to which the stamper is mounted flow. A low thermal conductive metal member having a thermal conductivity of 3/4 or less, a tensile strength of 300 MPa or more, and a melting point of 400 ° C. or more is provided between the member and the mirror surface member.
[0019]
A fourth mold for an optical disk substrate according to the present invention is a pair of fitted molds having a stamper mounted on at least one of them, and has a thermal conductivity of 15 W / mK or less between the stamper and the mold surface. It is characterized in that a certain low heat conductive metal member is provided.
[0020]
BEST MODE FOR CARRYING OUT THE INVENTION
The present invention is a mold for an optical disk substrate using a heat-insulating material that is strong against impact and has sufficient strength. Therefore, a member that forms at least a part of the cavity surface is a low heat conductive metal member. As the low thermal conductive metal member, a material containing titanium as a main component is preferable. Here, “main component” refers to 70% by weight or more.
[0021]
Further, it is preferable that the low thermal conductive metal material contains aluminum or vanadium. The preferred content is in the range of 2 to 7% by weight.
[0022]
The thickness of the low heat conductive metal member is preferably in the range of 0.5 mm or more and 3 mm or less. Preferably, the roughness of the cavity surface of the low thermal conductive metal member is 0.4 S or less.
[0023]
Further, it is preferable that the roughness of the side surface of the cavity of the low thermal conductive metal member be 0.1 S or less.
[0024]
Further, it is preferable that the roughness of the contact surface of the low heat conductive metal member with the stamper be 0.4 S or less.
[0025]
Hereinafter, specific embodiments of the present invention will be described in detail with reference to the drawings.
[0026]
(Embodiment 1)
The configuration of the optical disk substrate mold used in the first embodiment of the present invention is the same as the conventional heat insulating structure shown in FIG. The mold includes a fixed mold 1 and a movable mold 2. The stamper 3 is mounted on the fixed mold 1.
[0027]
The stationary mold 1 has a sprue bush 4 having a sprue portion into which a molten resin flows into a central portion. A stamper holder 5 is provided around the sprue bush 4 and holds the inside of the stamper 3. An outer peripheral ring 7 is provided on the outer peripheral side of the stamper 3 to hold the outside of the stamper 3. A heat insulating material 8 is provided on the back surface of the stamper 3, and the heat insulating material 8 is mounted on the fixed mirror plate 6 together with the stamper 3 by the stamper holder 5 and the outer peripheral ring 7. A groove for flowing a fluid for temperature adjustment is provided in the fixed side mirror plate 6, and is attached to the fixed side base 9. A fixed-side butting ring 17 is provided on the outer peripheral side of the fixed-side mirror panel 6.
[0028]
The movable mold 2 includes an ejector pin 10, a cut punch 11, an ejector sleeve 12, a movable-side fixed bush 13, and a movable-side mirror plate 14 from the inside. The cut punch 11 is for forming an inner hole in a molded product. The ejector pin 10 and the ejector sleeve 12 serve to push out the sprue and the molded product, respectively, when removing the molded product from the mold. The movable mirror plate 14 is also provided with a groove for flowing a fluid for temperature adjustment similarly to the fixed mirror disk 6, and is attached to the movable base 15. 20 is a cavity.
[0029]
A movable-side abutment ring 16 is provided at the outermost periphery of the movable mold 2, and is attached to the movable-side base 15. The movable-side abutment ring 16 performs positioning by abutting against a fixed-side abutment ring 17 attached to the fixed-side base 9.
[0030]
The material of the optical disk substrate mold is often made of stainless steel so as not to rust. The thermal conductivity in this case is 20 to 25 W / mK. The stamper 3 is made of nickel and has a thermal conductivity of about 90 W / mK. As the heat insulating material 8, a titanium alloy was selected as a metal having a lower thermal conductivity than stainless steel. As a titanium alloy, the main component (70% by weight or more) is titanium, and an alloy containing aluminum or vanadium (2 to 7% by weight) is easily finished into a thin plate. Thermal conductivity is 7-12 W / mK.
[0031]
The thickness of the heat insulating material 8 needs to be as precise as other mold members. In particular, parallelism is also important for suppressing in-plane variation. However, if it is thinner than 0.5 mm, it is difficult to obtain machining accuracy such as thickness accuracy and parallelism. For this reason, it is preferable to manufacture it thicker than 0.5 mm. Also, in order to investigate the relationship between the mold temperature required for the transfer and the thickness of the heat insulating material, the result of calculating the mold temperature at which the temperature reached by the stamper becomes 150 ° C. to 160 ° C. higher than the glass transition temperature of the polycarbonate resin by simulation. When the thickness is 2 mm or more, the mold temperature when the stamper reaches this specific ultimate temperature is almost saturated. Therefore, the thickness of the heat insulating plate is preferably 2 mm or less, more preferably 3 mm or less. Therefore, the thickness of the heat insulating material is preferably 0.5 mm or more and 3 mm or less.
[0032]
The heat insulating material was made of a titanium alloy having a thermal conductivity of 10 W / mK and a thickness of 2 mm, and the other members were made of stainless steel. Pits are formed on the stamper, and the stamper has a track pitch of 0.20 μm, a pit pitch of 0.24 μm, a pit length of 80 to 160 nm, and a depth of 65 nm.
[0033]
A substrate having a diameter of 120 mm and a thickness of 1.1 mm was made of a polycarbonate resin. The injection molding was performed at a maximum injection speed of 250 mm / s, a maximum clamping force of 30 tons, and a molding cycle of 10 seconds.
[0034]
The mold temperature at which a sufficient transfer can be obtained with a radius of 58 mm is 70 ° C. or higher when the heat insulating material 8 is provided, and is 90 ° C. or higher in the normal case without the heat insulating material 8. The mold temperature has dropped.
[0035]
The resin is heated to a maximum of around 400 ° C. in order to lower the viscosity of the resin flowing into the mold and make it easier to flow. The cavity surface in the mold is heated by the molten resin, and the temperature rises up to around 200 ° C. at the maximum. Therefore, the melting point of the mold member needs to be 400 ° C. or higher in order to stably maintain the shape. The melting point of the titanium alloy is about 1600 ° C.
[0036]
Further, in order to maintain a stable shape that can withstand a mechanical impact and a mold clamping force, a tensile strength of 300 MPa or more is required. The tensile strength of the titanium alloy is 800 MPa or more. When the mold is made of stainless steel except for the heat insulating material 8, when the thermal conductivity of the heat insulating material 8 is changed by simulation to obtain the mold temperature of the lower transfer limit, the lower limit of the transfer temperature when the entire mold is made of stainless steel is obtained. The transfer at a mold temperature lower than the mold temperature by 10 K or more was performed when the thermal conductivity of the heat insulating material was 15 W / mK or less.
[0037]
Although the above-mentioned mold is a case where most of the members are made of stainless steel, the mold can be made of another steel such as carbon steel or an aluminum alloy. In this case, the mold temperature at the lower transfer limit is determined by the ratio of the thermal conductivity between the heat insulating material 8 and another member. Therefore, the thickness of the heat insulating material 8 was fixed at 2 mm, and the heat conductivity of the heat insulating material was changed by simulation to determine the mold temperature at the lower transfer limit. Then, the transfer at a mold temperature 10 K or more lower than the mold lower limit of the transfer lower limit in the case where the whole is made of the same material is performed when the heat conductivity of the heat insulating material 8 is 3 times the heat conductivity of the members other than the heat insulating material 8. / 4 times or less.
[0038]
For example, the material other than the heat insulating material 8 is an aluminum alloy, and the heat insulating material 8 is nickel, steel, brass, bronze, stainless steel, or the like.
[0039]
So far, the case where all the mold members other than the heat insulating material 8 are made of the same material has been handled, but the thermal conductivity of the material of the fixed side mirror panel 6 which is in contact with the heat insulating material 8 and whose temperature is controlled is dominant. Was. That is, when the thermal conductivity of the heat insulating material 8 is 3/4 or less of the thermal conductivity of the fixed side mirror surface plate 6 in contact with the heat insulating material 8, the mold temperature at the transfer lower limit is 10K as compared with the case where the heat insulating material 8 is not provided. That's it.
[0040]
Similarly, when the thermal conductivity of the heat insulating material 8 is 15 W / mK or less and the fixed side mirror plate 6 below the heat insulating material 8 is made of stainless steel, the lower transfer limit of gold is lower than when the heat insulating material 8 is not provided. The mold temperature dropped by more than 10K.
[0041]
In the mold of the present invention, since the heat insulating material 8 has a melting point sufficiently higher than the highest temperature of the stamper 3 and is a metal having ductility and sufficient rigidity as compared with ceramic, the heat insulating material may be damaged during molding. However, the mold strength was sufficient.
[0042]
Next, the surface roughness of the heat insulating material 8 was examined. Since the thickness of the stamper 3 is about 0.3 mm, if the surface of the heat insulating material 8 has scratches or irregularities, it is transferred to the formed substrate. If the maximum surface roughness is 0.4 μm or less, the surface roughness of the molded substrate will not change when molded using a mirror-finished stamper. Not transferred through the stamper 3.
[0043]
In the first embodiment, the case where the stamper 3 is mounted on the fixed mold 1 side has been described. However, the stamper 3 may be mounted on the movable mold 2 or both the fixed mold 1 and the movable mold 2. It may be attached to. Similarly, the heat insulating material 8 may be provided not on the fixed mold 1 side but on the back side of the stamper 3 mounted on the movable mold 2 side.
[0044]
(Embodiment 2)
FIG. 2 shows the configuration of the optical disk substrate mold used in the second embodiment of the present invention. Compared to FIG. 1, in FIG. 2, there is no heat insulating material 8 on the back surface of the stamper 3 and the side opposite to the side where the stamper 3 is mounted, that is, here, on the movable mold 2 side, on the cavity side of the movable mirror plate 14. A heat insulating material 18 is provided on the surface. Since the heat insulating material 18 does not need to be attached or detached, it is welded to the movable mirror panel 14.
[0045]
In this case, it does not directly work on the heat conduction of the stamper 3 involved in the transfer, but the cooling of the molten resin that has flowed into the mold is delayed, so that the time required for the stamper 3 to be warmed by the molten resin is increased, and the transfer is improved. .
[0046]
Also in the second embodiment, the thickness of the heat insulating material 18 needs to be as precise as other mold members. In particular, parallelism is also important for suppressing in-plane variation. However, if it is thinner than 0.5 mm, it is difficult to obtain machining accuracy such as thickness accuracy and parallelism. For this reason, it is necessary to manufacture it thicker than 0.5 mm. In addition, in order to investigate the relationship between the mold temperature and the thickness of the heat-insulating material, the ultimate temperature of the heat-insulating material was calculated by making the mold temperature constant by simulation. Saturates. Therefore, it is sufficient that the thickness of the heat insulating plate is 2 mm or less, preferably 3 mm or less. Therefore, the thickness of the heat insulating material is preferably 0.5 mm or more and 3 mm or less.
[0047]
The heat insulating material 18 was made of a titanium alloy having a thermal conductivity of 10 W / mK and a thickness of 2 mm, and the other members were made of stainless steel. Pits are formed on the stamper, and the stamper has a track pitch of 0.20 μm, a pit pitch of 0.24 μm, a pit length of 80 to 160 nm, and a depth of 65 nm.
[0048]
A substrate having a diameter of 120 mm and a thickness of 1.1 mm was made of a polycarbonate resin. The injection molding was performed at a maximum injection speed of 250 mm / s, a maximum clamping force of 30 tons, and a molding cycle of 10 seconds.
[0049]
The mold temperature at which a sufficient transfer was obtained with a radius of 58 mm was 90 ° C. or higher in a normal case without the heat insulating material 18, and was 75 ° C. or higher in the case with the heat insulating material 18.
[0050]
The resin is heated to a maximum of around 400 ° C. in order to lower the viscosity of the resin flowing into the mold and make it easier to flow. The cavity surface in the mold is heated by the molten resin, and the temperature rises up to around 200 ° C. at the maximum. Therefore, the melting point of the mold member needs to be 400 ° C. or higher in order to stably maintain the shape.
[0051]
In addition, a tensile strength of 300 MPa or more is required to maintain a stable shape that can withstand mechanical shock and mold clamping force.
[0052]
When the mold is made of stainless steel except for the heat insulating material 18, when the thermal conductivity of the heat insulating material 18 is changed by simulation to determine the mold temperature of the lower transfer limit, the lower limit of the transfer temperature when the normal whole is made of stainless steel is obtained. The transfer at a mold temperature 10 K lower than the mold temperature was performed when the thermal conductivity of the heat insulating material 18 was 13 W / mK or less.
[0053]
Although the above-mentioned mold is a case where most of the members are made of stainless steel, the mold can be made of another steel such as carbon steel or an aluminum alloy. Also in this case, the mold temperature at the lower transfer limit is determined by the ratio of the thermal conductivity between the heat insulating material 18 and other members. Therefore, when the mold temperature of the lower transfer limit is obtained by changing the thermal conductivity of the heat insulating material 18, the transfer at the mold temperature lower by 10K or more than the mold temperature of the lower transfer limit when all the members are made of the same material is usually used. In this case, the heat conductivity of the heat insulating material 18 was not more than 2/3 times the heat conductivity of members other than the heat insulating material 18.
[0054]
For example, there is an aluminum alloy other than the heat insulating material 18 and the heat insulating material 18 is nickel, steel, brass, bronze, stainless steel, or the like.
[0055]
Up to now, the case where all the mold members other than the heat insulating material 18 are made of the same material has been handled. However, similarly to the heat insulating material 18, the heat conductivity of the members near the cavity, especially the material of the movable mirror panel 14 whose temperature is controlled. Was dominant. That is, when the thermal conductivity of the heat insulating material 18 is 2/3 times or less of the thermal conductivity of the movable mirror 14 below the heat insulating material 18, the mold temperature at the lower transfer limit is lower than when the heat insulating material 18 is not provided. It has dropped by more than 10K.
[0056]
Similarly, when the thermal conductivity of the heat insulating material 18 is 13 W / mK or less and the movable mirror 14 below the heat insulating material 18 is made of stainless steel, the lower transfer limit of gold is lower than when the heat insulating material 18 is not provided. The mold temperature dropped by more than 10K.
[0057]
In the mold of the present invention, since the heat insulating material 18 has a melting point sufficiently higher than the maximum temperature of the stamper 3 and is a metal having ductility and sufficient rigidity as compared with ceramic, the heat insulating material 18 is damaged during molding. The mold strength was sufficient.
[0058]
Next, regarding the surface state of the heat insulating material 18, if the surface of the heat insulating material 18 has scratches or irregularities, it is transferred to the molded substrate. Therefore, when the side where the heat insulating material 18 is located is the reproduction surface side of the optical disk, the surface roughness of the heat insulating material 18 is preferably 0.1 μm or less in maximum roughness.
[0059]
In the second embodiment, the heat insulating material 18 is used on the cavity surface of the movable mirror member 14. However, when the stamper 3 is mounted on the movable mold 2, the heat insulator 18 may be used on the cavity surface of the fixed mirror disk 6. Here, the movable mirror panel 14 and the heat insulating material 18 are welded, but of course, may be fixed by other means. Further, a mold structure in which the second embodiment is added to the first embodiment may be used.
[0060]
(Embodiment 3)
FIG. 3 shows the configuration of the optical disk substrate mold used in the third embodiment of the present invention. Compared to FIG. 1, in FIG. 3, the heat insulating material 8 is not provided on the back surface of the stamper 3, and the outer peripheral ring is formed by the heat insulating material 19 and the outer peripheral ring 7.
[0061]
Since the heat insulating material 19 does not need to be attached or detached, it is welded to the outer peripheral ring 7. In this case, it does not directly work on the heat conduction of the stamper 3 involved in the transfer, but the cooling of the molten resin that has flowed into the mold is delayed, so that the time required for the stamper 3 to be warmed by the molten resin is increased, and the transfer is improved. .
[0062]
Also in the third embodiment, the thickness of the heat insulating material 19 needs to be as accurate as other mold members. However, if it is thinner than 0.5 mm, it is difficult to obtain machining accuracy such as thickness accuracy and parallelism. For this reason, it is preferable to manufacture it thicker than 0.5 mm. In addition, in order to investigate the relationship between the mold temperature and the thickness of the heat insulating material 19, the ultimate temperature of the heat insulating material 19 was calculated with the mold temperature kept constant by simulation. The temperature was almost saturated.
[0063]
The heat insulating material 19 was made of a titanium alloy having a thermal conductivity of 10 W / mK and a thickness of 2 mm, and the other members were made of stainless steel. The stamper 3 has pits formed therein, and has a track pitch of 0.20 μm, a pit pitch of 0.24 μm, a pit length of 80 to 160 nm, and a depth of 65 nm.
[0064]
A substrate having a diameter of 120 mm and a thickness of 1.1 mm was made of a polycarbonate resin. The injection molding was performed at a maximum injection speed of 250 mm / s, a maximum clamping force of 30 tons, and a molding cycle of 10 seconds. The mold temperature at which a sufficient transfer was obtained with a radius of 58 mm was 90 ° C. or higher in a normal case without the heat insulating material 19 and was 75 ° C. or higher when the heat insulating material 19 was present.
[0065]
The resin is heated to a maximum of around 400 ° C. in order to lower the viscosity of the resin flowing into the mold and make it easier to flow. The cavity surface in the mold is heated by the molten resin, and the temperature rises up to around 200 ° C. at the maximum. Therefore, the melting point of the mold member needs to be 400 ° C. or higher in order to stably maintain the shape.
[0066]
In addition, a tensile strength of 300 MPa or more is required to maintain a stable shape that can withstand mechanical shock and mold clamping force.
[0067]
When the mold is made of stainless steel except for the heat insulating material 19, when the heat conductivity of the heat insulating material 19 is changed by simulation to obtain the mold temperature of the lower transfer limit, the lower limit of the transfer temperature when the normal whole is made of stainless steel is obtained. The transfer at the mold temperature 10 K lower than the mold temperature was performed when the thermal conductivity of the heat insulating material 19 was 13 W / mK or less.
[0068]
Although the above-mentioned mold is a case where most of the members are made of stainless steel, the mold can be made of another steel such as carbon steel or an aluminum alloy. Also in this case, the mold temperature at the lower transfer limit is determined by the ratio of the thermal conductivity between the heat insulating material 19 and other members. Therefore, when the thickness of the heat insulating material 19 is fixed at 2 mm and the thermal conductivity of the heat insulating material 19 is changed to obtain the mold temperature at the lower transfer limit, the mold temperature at the lower transfer limit when all the members are made of the same material is usually used. The transfer at a mold temperature lower by 10 K or more was performed when the thermal conductivity of the heat insulating material 19 was 2/3 or less of the thermal conductivity of the members other than the heat insulating material 19.
[0069]
For example, the material other than the heat insulating material 19 is an aluminum alloy, and the heat insulating material 19 is nickel, steel, brass, bronze, stainless steel, or the like.
[0070]
Until now, all the mold members other than the heat insulating material 19 were made of the same material. However, similarly to the heat insulating material 19, the thermal conductivity of the material in the vicinity of the cavity, particularly the material of the movable mirror 14 whose temperature is controlled is dominant. Met. That is, when the thermal conductivity of the heat insulating material 19 is 2/3 or less of the thermal conductivity of the movable mirror 14 in contact with the heat insulating material 19, the mold temperature at the lower transfer limit is 10K compared to the case where the heat insulating material 19 is not provided. That's it.
[0071]
Similarly, when the thermal conductivity of the heat insulating material 19 is 13 W / mK or less and the movable mirror 14 below the heat insulating material 19 is made of stainless steel, the transfer lower limit is lower than when the heat insulating material 19 is not provided. Of the mold decreased by 10K or more.
[0072]
In the mold of the present embodiment, the heat insulating material 19 has a melting point sufficiently higher than the maximum temperature of the stamper, and is a metal having ductility and sufficient rigidity as compared with ceramic. However, the mold strength was sufficient.
[0073]
Next, the surface state of the heat insulating material 19 is transferred to the molded substrate if the surface of the heat insulating material 19 has scratches, irregularities, or the like. Further, the heat insulating material 19 slides on the movable mirror panel 14. Therefore, the surface roughness of the heat insulating material 19 is preferably 0.4 μm or less in maximum roughness.
[0074]
In the third embodiment of the present invention, the conventional outer ring is constituted by the outer ring 7 and the heat insulator 19, but the outer ring 7 may be constituted by the heat insulator 19 alone.
[0075]
Embodiment 1 and Embodiment 2 may be added to Embodiment 3 of the present invention.
[0076]
In the second embodiment, the heat insulating material 18 is used for the cavity surface of the movable-side mirror surface plate 14. It may be used for the surface, or may be made of a heat insulating material itself.
[0077]
【The invention's effect】
According to the present invention, it is possible to obtain a mold for an optical disk substrate which can transfer a molded substrate even at a low mold temperature and has sufficient strength against impact. Therefore, molding using a high-density stamper becomes possible.
[Brief description of the drawings]
FIG. 1 is a schematic cross-sectional view showing a configuration of a mold used in a first embodiment of the present invention and a conventional example. FIG. 2 is a schematic cross-sectional view showing a configuration of a second embodiment of the present invention. Schematic sectional view showing the structure of the third embodiment.
REFERENCE SIGNS LIST 1 fixed mold 2 movable mold 3 stamper 4 sprue bush 5 stamper holder 6 fixed side mirror face plate 7 outer ring 8, 18, 19 heat insulating material 9 fixed side base 10 ejector pin 11 cut punch 12 ejector sleeve 13 movable side fixed bush 14 Movable mirror plate 15 Movable base 16 Movable butting ring 17 Fixed butting ring 20 Cavity

Claims

A pair of mating dies with a stamper mounted on at least one,
The member forming at least a part of the cavity surface is a low heat conductive metal member having a thermal conductivity of 2/3 or less of a member forming the cavity surface other than the stamper, a tensile strength of 300 MPa or more, and a melting point of 400 ° C. or more. A mold for an optical disc substrate characterized by being formed.

A pair of mating dies with a stamper mounted on at least one,
A mold for an optical disc substrate, wherein a member forming at least a part of a cavity surface is formed of a low heat conductive metal member having a thermal conductivity of 13 W / mK or less, a tensile strength of 300 MPa or more, and a melting point of 400 ° C. or more. .

A pair of mating dies with a stamper mounted on at least one,
Low heat having a thermal conductivity of ３ or less of the mirror member, a tensile strength of 300 MPa or more, and a melting point of 400 ° C. or more between the stamper and the mirror member on which the temperature adjusting medium on the side where the stamper is mounted is flown. A mold for an optical disk substrate, comprising a conductive metal member.

A pair of mating dies with a stamper mounted on at least one,
A mold for an optical disc substrate, wherein a low heat conductive metal member having a thermal conductivity of 15 W / mK or less is provided between a stamper and a mold surface.

5. The optical disk substrate mold according to claim 2, wherein the low thermal conductive metal member is made of a material containing titanium as a main component.

The optical disk substrate mold according to claim 5, wherein the low thermal conductive metal member contains aluminum or vanadium.

The mold for an optical disk substrate according to any one of claims 1 to 4, wherein the thickness of the low thermal conductive metal member is in a range of 0.5 mm or more and 3 mm or less.

The mold for an optical disk substrate according to claim 1 or 2, wherein the roughness of the cavity surface of the low thermal conductive metal member is 0.4S or less.

9. The optical disk substrate mold according to claim 8, wherein the roughness of the side surface of the cavity of the low thermal conductive metal member is 0.1 S or less.

5. The optical disk substrate mold according to claim 3, wherein a roughness of a contact surface of the low thermal conductive metal member with the stamper is 0.4 S or less.