JP2004059368A

JP2004059368A - Molding mold and method of manufacturing molding mold

Info

Publication number: JP2004059368A
Application number: JP2002219453A
Authority: JP
Inventors: Tadashi Okamoto; 匡史岡本; Hidenao Kataoka; 秀直片岡; Tatsuhiko Inagaki; 辰彦稲垣; Kunio Hibino; 邦男日比野; Minoru Onoda; 稔小野田; Tomoyasu Murakami; 友康村上; Hiroshi Minasawa; 宏皆澤
Original assignee: Fuji Electric Holdings Ltd; Matsushita Electric Industrial Co Ltd
Current assignee: Fuji Electric Co Ltd; Panasonic Holdings Corp
Priority date: 2002-07-29
Filing date: 2002-07-29
Publication date: 2004-02-26

Description

【０００１】
【発明の属する技術分野】
本発明は、主としてガラスを成形対象とする成形用金型、より詳しくは、金型母材の保護膜としてイリジウム系の貴金属合金の保護膜を有する成形用金型および成形用金型の製造方法に関する。本発明における成形用金型は、その成形対象を情報記録媒体のガラス基板とするときに、優れて大きな効果を発揮する。
【０００２】
【従来の技術】
情報記録媒体の一例である磁気ディスクの基板について、近年、小型化、大容量化のニーズの高まりがあり、旧来のアルミニウム基板に代わって、高剛性、高強度で、平滑化が容易なガラス基板が採用されている。その場合に、生産性が低く高価につく研磨法に代わって、光学素子の製造の分野におけるプレス成形法の技術を転用する動向がある。プレス成形法は、ガラス素材を加熱して軟化する工程、加圧成形する工程、冷却する工程を経ることにより、金型の高精度に平滑な成形面をガラス素材に転写するものであり、後加工の研磨を必要としない。そのため、高品質な上に安価で生産性が高い。プレス成形法は、光学素子製造の分野では既に実用化が図られているが、磁気ディスクなどの情報記録媒体用のガラス基板にそのまま単純に適用しても、小型化、薄型化、高記録密度化、高信頼性の面で充分に望ましい結果は得にくいのが実情である。
【０００３】
プレス成形に用いる成形用金型として、金型母材のプレス面に密着性が高いとされるカーボンコートを施した成形用金型が提案されている（特開平７−１０５６１号公報、特開平９−１９４２２７号公報参照）。しかし、本発明者らの研究によれば、カーボンコートの成形用金型には次のような不都合がある。
【０００４】
（１）成形を繰り返すうちに保護膜からカーボンが脱離し微細なパーティクルとなる。このパーティクルがガラス基板上に付着し、基板の面精度の劣化を招く。
【０００５】
（２）成形時の温度が６００℃を超える場合は、窒素雰囲気でも成形室内に残存している微量な酸素とカーボンが反応し、二酸化炭素を生成する。その結果、カーボン膜は徐々に侵食されてしまう。
【０００６】
（３）６００℃以下の低温で成形が可能なガラス材料はあることはある。しかし、磁気ディスク用のガラス基板は、機械的強度やアルカリ成分の溶出量などの面で要求が非常に厳しく、対応が困難である。
【０００７】
一方、光学素子用の金型において、イリジウムや金、白金などの貴金属、またはそれらを含む合金を成形面にコートした成形用金型が提案されている（特開平５−１７８６２７号公報、特開平８−１４３３２０号公報参照）。中でも、イリジウム系の貴金属合金の保護膜は、他の貴金属系保護膜に比べて硬度が高いため、成形を繰り返しても表面に傷がつきにくく、長時間にわたる表面精度の確保が期待できる。
【０００８】
【発明が解決しようとする課題】
我々は、上記のように最も優れた保護膜材料の１つであるイリジウム系の貴金属合金の保護膜に関して、さらに深く研究を行った。イリジウム系の貴金属合金の保護膜を有する成形用金型は、初期のうちはきわめて高度な表面平滑性・平坦度を保っているが、プレス成形を繰り返すうちに、ｎｍオーダーで次第に表面平滑性・平坦度に劣化が進む。その原因を究明したところ、以下に示すような現象が生じていることを解明した。すなわち、イリジウム系の貴金属合金は高い融点を持つため、例えばスパッタ法にて成膜を行った直後では、膜は熱的な安定状態に達しない。高温下でプレス成形を繰り返し行っている間にも熱的安定状態に向けて内部状態が遷移していると考えられる。その結果、保護膜の内部で構成元素の拡散現象や粒成長が原因と考えられる面精度の劣化が生じ、所定の表面品質が得られなくなる。
【０００９】
ところで、この不都合を解決するため、金型をプレス成形に供する前に、アニールを施して熱的な安定状態を得る方法が考えられる。しかしながら、単にアニールを施すだけではアニール中に面精度が劣化してしまう。
【００１０】
さらに、面精度が劣化したアニール後の面を研磨することで表面精度を回復する方法も考えられる。しかしながら、我々の検討の結果、アニール後の膜表面は、アニール前の表面に比べ、研磨時にスクラッチ（傷）が発生しやすく（研磨材中に含まれるダイアモンド砥粒によると考えられる）、十分な表面品質を確保することができない。
【００１１】
本発明は、このような事情に鑑みて創作されたものであり、イリジウム系の貴金属合金の保護膜を有する成形用金型を前提として、プレス成形を繰り返しても表面平滑性、平坦度が劣化せず、長期間にわたって高品位な表面状態を維持できる成形用金型を提供することを目的としている。
【００１２】
【課題を解決するための手段】
上記の課題を解決するために、本発明は成形用金型について次のような手段を講じる。すなわち、金型の母材のプレス面側に形成する保護膜について、イリジウム（Ｉｒ）を主材とする材料で保護膜を構成することを前提にする。前記母材について好ましいものは、超硬合金、サファイアまたは炭化珪素を主成分とする材料で構成されている母材である。前記保護膜は、イリジウムだけでなく、イリジウムを主材としてさらに１種以上の貴金属元素を含む材料で構成する。その貴金属元素について好ましいものは、ロジウム（Ｒｈ）、ルテニウム（Ｒｕ）、パラジウム（Ｐｄ）およびレニウム（Ｒｅ）からなる群より選ばれた少なくとも１種の元素である。これらの群のうち任意の複数の元素を組み合わせてよい。そして、このイリジウムと貴金属元素からなる保護膜の膜性状を安定化するために、所定時間にわたって、前記保護膜を前記母材に押圧する所定の圧力を印加しながら所定の温度範囲で熱処理（加圧熱処理）を施して成形用金型を得る。
【００１３】
以上を要するに、本発明の成形用金型は、母材と、前記母材のプレス面側に形成された保護膜とを有し、前記保護膜は、イリジウム（Ｉｒ）を主材としてさらに１種以上の貴金属元素を含む材料で構成され、前記保護膜には加圧熱処理が施されているものである。イリジウムを主材として貴金属元素を含む保護膜とすることと、保護膜の膜性状を安定化するのに加圧しながらの熱処理である加圧熱処理を行うことに特徴がある。
【００１４】
これによる作用は次のとおりである。圧力を印加しながら熱処理を施す状態を所定時間保持する加圧熱処理により、保護膜における構成元素の粒成長や拡散現象に起因する面精度の劣化（面荒れ）を抑制しつつ、保護膜を熱的に安定な状態に遷移させることができる。この粒成長や拡散現象に起因する面精度の劣化を抑制した状態での熱的安定状態への遷移の作用は、圧力印加を伴わない単なる熱処理や、そのような単なる熱処理に引き続いての研磨処理では得られない特異な作用である。熱処理前に持っていた高い面精度を保ちつつ、熱的安定状態に達した保護膜を得ることができる。このように粒成長や拡散現象に起因する面精度の劣化を防止しながら熱的安定状態に達した保護膜は、もはや、成形時の加熱によっては表面状態は変化しないものになっている。さらに、イリジウム系の貴金属合金を保護膜としているので、他の貴金属系の保護膜に比べて硬度が高く、繰り返し成形に対する表面防傷性が良好である。この表面精度が高く安定した保護膜を有する成形用金型は、長期間にわたってガラスのプレス成形を良好に行うことができる。
【００１５】
別の解決手段として、本発明は成形用金型について次のような手段を講じる。すなわち、金型の母材のプレス面側に形成する保護膜について、第１の保護膜と第２の保護膜との複層保護膜とする。第１の保護膜は、イリジウム以外の１種以上の貴金属元素を含む材料で構成する。その貴金属元素について好ましいものは、ロジウム（Ｒｈ）、ルテニウム（Ｒｕ）、パラジウム（Ｐｄ）およびレニウム（Ｒｅ）からなる群より選ばれた少なくとも１種の元素である。これらの群のうち任意の複数の元素を組み合わせてよい。第２の保護膜はイリジウムを主材とする材料で構成する。前記母材について好ましいものは、サファイアまたは炭化珪素を主成分とする材料で構成されている母材である。そして、貴金属元素またはその合金の第１の保護膜とイリジウムの第２の保護膜とを合金層に変化させつつその膜性状を安定化するために、所定時間にわたって、前記第１および第２の保護膜を前記母材に押圧する所定の圧力を印加しながら所定の温度範囲で熱処理（加圧熱処理）を施して成形用金型を得る。なお、母材について超硬合金に言及していないのは、次の理由による。２つの保護膜の拡散によって合金化するのに、低い温度では処理時間が長くなる。所定の時間範囲で合金化を行うには高い温度での加圧熱処理が必要となる。しかし、超硬合金は耐熱温度が低いことから、処理時間が大幅に長くなることを余儀なくされ、実用的ではなくなる。
【００１６】
以上を要するに、本発明の成形用金型は、母材と、前記母材のプレス面側に形成された第１の保護膜と、前記第１の保護膜の上に形成された第２の保護膜とを有し、前記第１の保護膜は、イリジウム以外の１種以上の貴金属元素を含む材料で構成され、前記第２の保護膜はイリジウム（Ｉｒ）を主材とする材料で構成され、前記第１の保護膜および第２の保護膜には加圧熱処理が施されているものである。
【００１７】
これによる作用は次のとおりである。圧力を印加しながら熱処理を施す状態を所定時間保持する加圧熱処理により、拡散現象に基づいて第１および第２の保護膜を合金化するが、その合金層の保護膜における構成元素の粒成長や拡散現象に起因する面精度の劣化（面荒れ）を抑制しつつ、保護膜を熱的に安定な状態に遷移させることができる。この粒成長や拡散現象に起因する面精度の劣化を抑制した状態での熱的安定状態への遷移の作用は、圧力印加を伴わない単なる熱処理や、そのような単なる熱処理に引き続いての研磨処理では得られない特異な作用である。熱処理前に持っていた高い面精度を保ちつつ、熱的安定状態に達した合金層の保護膜を得ることができる。このように粒成長や拡散現象に起因する面精度の劣化を防止しながら熱的安定状態に達した合金層の保護膜は、もはや、成形時の加熱によっては表面状態は変化しないものになっている。また、繰り返し成形に対する表面防傷性が良好である。この表面精度が高く安定した合金層の保護膜を有する成形用金型は、長期間にわたってガラスのプレス成形を良好に行うことができる。
【００１８】
さらに、貴金属元素またはその合金の第１の保護膜とイリジウムの第２の保護膜とを積層した上で加圧熱処理により合金層の保護膜とするから、第１の保護膜についても第２の保護膜についてもその組成構成の自由度が高いものとなっている。この点において、粒成長や拡散現象に起因する面精度の劣化を防止する上で、より適切な対応をとりやすい。
【００１９】
上記の複層保護膜の合金化の場合には、加圧熱処理における温度が１層保護膜の場合に比べてより高いものとなる。そのため、母材として超硬合金の利用はむずかしく、サファイアや炭化珪素が好ましいものとなる。ところで、所定の大きさをもつサファイアや炭化珪素の入手が困難な場合がある。また、入手できるとしても価格が高い場合がある。そこで、母材の全体をサファイアまたは炭化珪素で構成することに代えて、一部を超硬合金等のベース材で構成し、ベース材の上にサファイアまたは炭化珪素を主成分とする材料で構成された母材主部を形成することが考えられる。このように工夫することにより、比較的安価に所要の大きさの母材を得ることができ、成形用金型の製造が容易となり、またコストを低減できる。
【００２０】
熱的な安定状態を得るための熱処理と表面精度を出すための研磨との順序に関しては、研磨を先に行い、研磨後に加圧熱処理を行うものとする。すなわち、保護膜または第２の保護膜を形成した後に、保護膜または第２の保護膜に対して研磨を行い、その後に、保護膜または第１および第２の保護膜に対する熱処理、それも圧力印加を伴う熱処理（加圧熱処理）を実施する。熱処理後に研磨を施す場合には、上述のように、研磨時にスクラッチが発生しやすい。これに対して、本発明のように、研磨した後に加圧熱処理を行うと、保護膜または第２の保護膜の表面である研磨面にはスクラッチは実質的に発生しない。すなわち、表面平滑性・平坦度が高度に優れたものとなる。
【００２１】
上記において、母材と保護膜または第１の保護膜との付着性が不足する場合には、次のように構成することが好ましい。すなわち、母材のプレス面側にタンタル（Ｔａ）やクロム（Ｃｒ）などの接着層を形成し、接着層の上に保護膜または第１の保護膜を形成する。これにより、母材と保護膜または第１の保護膜との付着力を強化することができる。
【００２２】
上記において、加圧熱処理の条件については、次のように設定することが好ましい。
【００２３】
超硬合金を主成分とする材料で構成された母材のプレス面側に、保護膜としてイリジウムを主材とし、ロジウム、ルテニウム、パラジウムおよびレニウムからなる群より選ばれた少なくとも１種の元素を含む保護膜を形成し、次いで加圧熱処理を行う場合は、１０〜１００ｋｇｆ／ｃｍ^２の圧力を印加しながら、６５０〜７５０℃の温度範囲で、１４〜５０時間にわたって加圧熱処理を行うのが好ましい。超硬合金製の母材の耐熱性の面および処理時間の面から６５０〜７５０℃とする。７５０℃を超えると耐熱性に問題が生じる。６５０℃を下回ると処理時間上不利となる。
【００２４】
また、サファイア製または炭化珪素製の母材のプレス面側に、保護膜としてイリジウムを主材とし、ロジウム、ルテニウム、パラジウムおよびレニウムからなる群より選ばれた少なくとも１種の元素を含む保護膜を形成し、次いで加圧熱処理を行う場合は、１０〜１００ｋｇｆ／ｃｍ^２の圧力を印加しながら、６５０〜８５０℃の温度範囲で、５〜５０時間にわたって加圧熱処理を行うのが好ましい。６５０℃を下回ると処理時間上不利となる。サファイヤや炭化珪素は８５０℃を超える耐熱温度を有し、上記温度範囲よりもさらに高い温度で熱処理することは可能である。しかし、一般的な熱処理炉では昇温・冷却過程で要する時間の増分を考慮すると、熱処理温度を８５０℃を超えて高くしても、全体の処理時間にはあまり変化がない。したがって、消費エネルギーの面で８５０℃以下とする。
【００２５】
母材が超硬合金製の場合もサファイア製または炭化珪素製の場合も、保護膜における構成元素の粒成長や拡散現象に起因する面精度の劣化（面荒れ）を抑制しつつ保護膜を熱的に安定な状態に遷移させる上では、印加圧力は１０〜１００ｋｇｆ／ｃｍ^２とするのが好ましい。１０ｋｇｆ／ｃｍ^２未満であれば粒成長や拡散現象に起因する面精度の劣化の抑制がむずかしい。１００ｋｇｆ／ｃｍ^２を超えても効果に余り変わりがない。
【００２６】
また、サファイア製または炭化珪素製の母材のプレス面側に、ロジウム、ルテニウム、パラジウムおよびレニウムからなる群より選ばれた少なくとも１種の元素を含む材料で構成された第１の保護膜を形成し、次いで第１の保護膜の上にイリジウムを主材とする材料で構成された第２の保護膜を形成し、次いで加圧熱処理を行う場合には、１０〜１００ｋｇｆ／ｃｍ^２の圧力を印加しながら、１０００〜１４００℃の温度範囲で、５〜５０時間にわたって加圧熱処理を行うのが好ましい。貴金属元素またはその合金の第１の保護膜とイリジウムの第２の保護膜とを積層した上で加圧熱処理により合金層の保護膜とするから、第１の保護膜も第２の保護膜も組成構成の自由度が高いものとなる。そして、合金層の保護膜における構成元素の粒成長や拡散現象に起因する面精度の劣化（面荒れ）を抑制しつつ、保護膜を熱的に安定な状態に遷移させるには、温度範囲として１０００〜１４００℃が好ましい。１０００℃を下回ると処理時間上不利となる。上記温度範囲よりもさらに高い温度で熱処理することは可能である。しかし、一般的な熱処理炉では昇温・冷却過程で要する時間の増分を考慮すると、熱処理温度を１４００℃を超えて高くしても、全体の処理時間にはあまり変化がない。したがって、消費エネルギーの面で１４００℃以下とする。
【００２７】
また、上記において、加圧熱処理における圧力印加の態様として、１対の成形用金型のプレス面同士を押し当て、互いに押圧することが好ましい。一度で、２つの成形用金型に対する加圧熱処理が行え、作業効率が高く、製造コストを低減できる。
【００２８】
以上のように、本発明によれば、長期間にわたって高度に優れた表面平滑性・平坦度を有する成形用金型を得ることができる。特に、情報記録媒体のガラス基板の成形に本発明の成形用金型を適用すると、優れて大きな効果を発揮し、高温条件下でガラス基板のプレス成形を繰り返し行っても、表面精度の優れたガラス基板を得ることができる。
【００２９】
【発明の実施の形態】
以下、本発明にかかわる成形用金型およびその製造方法の実施の形態について図面に基づいて詳細に説明する。
【００３０】
（実施の形態１）
図１は本発明の実施の形態１における成形用金型の加圧熱処理（アニール）の様子を示す断面図である。図１に示した１対の成形用金型１，１はそれぞれ、金型母材２および保護膜３からなる。金型母材２としては、超硬合金（タングステンカーバイドの焼結体）、サファイア、炭化珪素（ＳｉＣ）等で構成されたものが用いられる。これらの材料に切削、研磨等の加工を施し、所定の形状および表面精度の金型母材２とする。
【００３１】
スパッタ法等の薄膜形成方法を用いて母材２上に保護膜３を形成する。ここで、母材や保護膜の種類によっては、その間の付着力が不充分な場合がある。その場合は、保護膜３の下地層としてタンタル（Ｔａ）、クロム（Ｃｒ）等の接着層（図示せず）を形成する。
【００３２】
保護膜３を形成した後、図示のように、１対の成形用金型１，１の成形面を対向および対接させて、図示しない加熱炉中で、１０〜１００ｋｇｆ／ｃｍ^２程度の圧力を加えながら熱処理を行う（加圧熱処理）。このときの熱処理温度については、処理時間に短縮上、より高温の方が好ましいが、成形用金型１の母材２の耐熱性を考慮すると、超硬合金を使用する場合は６５０〜７５０℃が好ましい。
【００３３】
また、母材２にサファイアや炭化珪素（ＳｉＣ）を用いる場合は、好ましい熱処理温度は６５０〜８５０℃である。サファイヤや炭化珪素の耐熱性が高いので、さらに高温で熱処理することは可能ではある。しかし、一般的な熱処理炉では昇温・冷却過程で要する時間の増分が大きくなるので、熱処理温度を８５０℃を超えて上げても、実際の処理時間短縮の効果がほとんどない。この理由で、好適温度上限を８５０℃に定めている。なお、処理温度が８００℃以下であれば、処理時間は長くなるが、成形機で一般的に用いられるカートリッジヒータで昇温が可能であり、成形機を熱処理炉として代用できるので、設備投資額を抑制できるという利点がある。
【００３４】
この加圧熱処理により保護膜３は熱的に安定な状態に向かう。その際、同時に圧力を加えることにより、粒成長や拡散現象によって起きると考えられる面精度の悪化（面荒れ）を防ぐことができる。
【００３５】
こうして、熱処理前に持っていた高い面精度を保ちつつ、熱的安定状態に達した保護膜３を得ることができる。この保護膜３はガラス基板のプレス成形時の加熱によっては表面状態が変化しないものとなる。このようにして、安定した表面状態を維持し、長期間にわたって良好なガラス基板のプレス成形を行える成形用金型を得ることができる。
【００３６】
（実施の形態２）
図２は本発明の実施の形態２における成形用金型の加圧熱処理の様子を示す断面図である。図２に示した１対の成形用金型１，１は、母材２、第１の保護膜３ａ、第２の保護膜３ｂからなる。母材２としては、所望の形状、表面精度を持ったサファイアまたは炭化珪素（ＳｉＣ）で構成されたものが用いられる。
【００３７】
スパッタ法等の薄膜形成方法を用いて母材２上にまず第１の保護膜３ａを形成し、続いて第２の保護膜３ｂを形成する。ここで、母材や膜の種類によっては、その間の付着力が不充分な場合がある。その場合は、第１の保護膜３ａの下地層としてタンタル、クロム等の接着層（図示せず）を形成する。
【００３８】
第１の保護膜３ａおよび第２の保護膜３ｂを形成した後、図示のように、１対の成形用金型１，１の成形面を対向および対接させて、図示しない加熱炉中で、１０〜１００ｋｇｆ／ｃｍ^２程度の圧力を加えながら熱処理を行う（加圧熱処理）。この熱処理により、第１の保護膜３ａの構成粒子が第２の保護膜３ｂ中に拡散し、その結果、熱的安定状態を持つ合金層（図示せず）が形成される。このときの熱処理温度については、１０００℃から１４００℃が望ましい。熱的安定状態が得られる熱処理時間については、１０００℃で約５０時間、１４００℃で約５時間であった。好適温度の下限は、適切な作業時間から決定される。好適温度の上限は、実施の形態１で述べたように、実際の処理時間短縮の効果がほとんどないことから決定される。
【００３９】
なお、膜の拡散係数Ｄが、Ｂｒｉａｎ　Ｒｅｅｄ　ｅｔ．　ａｌ．，Ｒｈｅｎｉｕｍ　ａｎｄＲｈｅｎｉｕｍ　Ａｌｌｏｙｓ　ｐ４４３−４５７，Ｔｈｅ　Ｍｉｎｅｒａｌｓ　Ｍｅｔａｌｓ＆Ｍａｔｅｒｉａｌｓ　Ｓｏｃｉｅｔｙ（１９９７）に示された式、すなわち、Ｅ＝１．２３（ｅＶ）、Ｔは温度（Ｋ）、ｋはボルツマン定数で、ｋ＝１．３８×１０^−２３Ｊ／Ｋとして、
Ｄ＝Ｄ_０・ｅｘｐ（−Ｅ／ｋＴ）
に従うと仮定すると、７５０℃の熱処理温度では、５００時間以上の熱処理が必要となる。超硬合金は、耐熱温度が低いために熱処理温度を７５０℃より高くできない。したがって、保護膜を２層とする場合には、超硬合金を母材２の材料として選択するのは実用的でない。
【００４０】
この熱処理により２層構造であった第１の保護膜３ａおよび第２の保護膜３ｂは、拡散現象により合金層を形成する。その際、圧力を加えることにより、粒成長や拡散現象によって起きると考えられる面精度の悪化（面荒れ）を防ぐことが可能となる。
【００４１】
こうして、熱処理前に持っていた高い面精度を保ちつつ、熱的安定状態に達した合金層を得ることができる。この合金層は、ガラス基板のプレス成形時の加熱によっては表面状態が変化しないようになる。このようにして、安定した表面状態を維持でき、その結果、長期間にわたってガラス基板に対するプレス成形を行える成形用金型を得ることができる。
【００４２】
上記において、サファイアや炭化珪素については、必要な体積を持つ材料が入手困難な場合や、仮に入手できても非常に高価な場合がある。その場合、図３に示すように、超硬合金等で構成されたベース材４を利用するとよい。すなわち、サファイア製または炭化珪素製の母材２の上に第１および第２の保護膜３ａ，３ｂを形成した上で、加圧熱処理を施して成形用金型の半製品を構成し、その半製品における母材２を前記のベース材４の上に固定することにより成形用金型に構成することも可能である。
【００４３】
【実施例】
本発明の効果を確認するため、以下の条件で成形を行った。
【００４４】
図４に今回行ったガラスの成形法の工程図を示す。図４（Ａ）に示すように、成形装置（図示せず）内に１対の成形用金型１，１をその保護膜３，３の表面である成形面が互いに向き合うように取り付けてある。下側の成形用金型１の成形面の上に、軟化点温度が６３０℃のアルミノシリケートガラスのガラスプリフォーム５を投入した。次いで、図４（Ｂ）に示すように、高温下で成形用金型１，１によりガラスプリフォーム５をプレスした。このときのプレス条件は、温度６２０℃、圧力は最大２００ｋｇｆ／ｃｍ^２とした。なお、加熱中は酸化を防止する目的で、成形装置内に窒素ガスを流し続けた。その後、図４（Ｃ）に示すように、成形用金型１，１から取り出してガラス成形品５′を得た。
【００４５】
以下の実施例、比較例に示した金型を用いて、上記プロセスをそれぞれ１０００回（ショット）行った。表１に金型の構成と成形後の表面状態の変化を示した。
【００４６】
【表１】

【００４７】
（実施例１）
直径１１０ｍｍの円柱の超硬合金（ＷＣ−Ｃｏ）製の金型母材に、接着層としてタンタル約０．５μｍを高周波スパッタ法にて形成した後、同じく高周波スパッタ法にて、イリジウム−ロジウム（Ｉｒ９５Ｒｈ５（原子％））の保護膜を３μｍ形成した。その後、この金型２個を表面粗さ（Ｒａ：中心線平均粗さ）が０．６ｎｍになるよう、研磨（ラップ）加工を施した。研磨の結果、保護膜の厚みは約２μｍとなった。
【００４８】
これらの金型を洗浄した後、２つの金型の成形面同士を合わせて、酸素濃度が３０ｐｐｍ以下にコントロールされた窒素雰囲気のチャンバー内に入れ、プレス圧力５０ｋｇｆ／ｃｍ^２を加えながら、７００℃まで加熱し、この状態を２５時間保持した。
【００４９】
こうして作製した金型２個の表面粗さを測定したが、アニール前の表面粗さ０．６ｎｍを保っていた。
【００５０】
その後、前述の条件下でプレス成形を１０００ショット繰り返したが、アニール後（成形前）の粗さ０．６ｎｍを保っていた。
【００５１】
（実施例２）
直径１１０ｍｍの円柱の超硬合金（ＷＣ−Ｃｏ）製の金型母材に、接着層としてタンタル約０．５μｍを高周波スパッタ法にて形成した後、同じく高周波スパッタ法にて、イリジウム−ルテニウム（Ｉｒ９０Ｒｕ１０（原子％））の保護膜を３μｍ形成した。その後、この金型２個を表面粗さ（Ｒａ）が０．６ｎｍになるよう、研磨（ラップ）加工を施した。研磨の結果、保護膜の厚みは約２μｍとなった。
【００５２】
これらの金型を洗浄した後、２つの金型の成形面同士を合わせて、酸素濃度が３０ｐｐｍ以下にコントロールされた窒素雰囲気のチャンバー内に入れ、プレス圧力５０ｋｇｆ／ｃｍ^２を加えながら、７００℃まで加熱し、この状態を２５時間保持した。
【００５３】
こうして作製した金型２個の表面粗さを測定したが、アニール前の表面粗さ０．６ｎｍを保っていた。
【００５４】
その後、前述の条件下でプレス成形を１０００ショット繰り返したが、アニール後（成形前）の粗さ０．６ｎｍを保っていた。
【００５５】
（実施例３）
直径１１０ｍｍの円柱の超硬合金（ＷＣ−Ｃｏ）製の金型母材に、接着層としてタンタル約０．５μｍを高周波スパッタ法にて形成した後、同じく高周波スパッタ法にて、イリジウム−パラジウム（Ｉｒ９８Ｐｄ２（原子％））の保護膜を３μｍ形成した。その後、この金型２個を表面粗さ（Ｒａ）が０．６ｎｍになるよう、研磨（ラップ）加工を施した。研磨の結果、保護膜の厚みは約２μｍとなった。
【００５６】
これらの金型を洗浄した後、２つの金型の成形面同士を合わせて、酸素濃度が３０ｐｐｍ以下にコントロールされた窒素雰囲気のチャンバー内に入れ、プレス圧力５０ｋｇｆ／ｃｍ^２を加えながら、７００℃まで加熱し、この状態を２５時間保持した。
【００５７】
こうして作製した金型２個の表面粗さを測定したが、アニール前の表面粗さ０．６ｎｍを保っていた。
【００５８】
その後、前述の条件下でプレス成形を１０００ショット繰り返したが、アニール後（成形前）の粗さ０．６ｎｍを保っていた。
【００５９】
（実施例４）
直径１１０ｍｍの円柱の超硬合金（ＷＣ−Ｃｏ）製の金型母材に、接着層としてタンタル約０．５μｍを高周波スパッタ法にて形成した後、同じく高周波スパッタ法にて、イリジウム−レニウム（Ｉｒ６０Ｒｅ４０（原子％））の保護膜を２μｍ形成した。その後、２つの金型の成形面同士を合わせて、酸素濃度が３０ｐｐｍ以下にコントロールされた窒素雰囲気のチャンバー内に入れ、プレス圧力５０ｋｇｆ／ｃｍ^２を加えながら、７００℃まで加熱し、この状態を２５時間保持した。研磨（ラップ）加工は行わなかった。
【００６０】
こうして作製した金型２個の表面粗さを測定したが、アニール前の表面粗さ２．０ｎｍを保っていた。
【００６１】
その後、前述の条件下でプレス成形を１０００ショット繰り返したが、アニール後（成形前）の粗さ２．０ｎｍを保っていた。
【００６２】
（実施例５）
直径１１０ｍｍの円柱のサファイア（単結晶アルミナ）製の金型母材に、接着層としてタンタル約０．５μｍを高周波スパッタ法にて形成した後、同じく高周波スパッタ法にて、まず第１の保護膜としてレニウムを１．５μｍ形成し、続いて第２の保護膜としてイリジウムを１．５μｍ形成した。その後、この金型２個を表面粗さ（Ｒａ）が０．６ｎｍになるよう、研磨（ラップ）加工を施した。このときの研磨量は約１μｍであった。この時点で、保護膜の構成は、下地からレニウム１．５μｍ、イリジウム０．５μｍとなった。
【００６３】
これらの金型を洗浄した後、２つの金型の成形面同士を合わせて、酸素濃度が３０ｐｐｍ以下にコントロールされた窒素雰囲気のチャンバー内に入れ、プレス圧力５０ｋｇｆ／ｃｍ^２を加えながら、１２００℃まで加熱し、この状態を１４時間保持した。
【００６４】
こうして作製した金型２個の表面粗さを測定したが、アニール前の表面粗さ０．６ｎｍを保っていた。
【００６５】
その後、前述の条件下でプレス成形を１０００ショット繰り返したが、アニール後（成形前）の粗さ０．６ｎｍを保っていた。
【００６６】
（実施例６）
直径１１０ｍｍの円板状の炭化珪素（ＳｉＣ）製の金型母材に、接着層としてタンタル約０．５μｍを高周波スパッタ法にて形成した後、同じく高周波スパッタ法にて、まず第１の保護膜としてパラジウムを１．５μｍ形成し、続いてイリジウムを１．５μｍ形成した。その後、この金型２個を表面粗さ（Ｒａ）が０．６ｎｍになるよう、研磨（ラップ）加工を施した。このときの研磨量は約１μｍであった。この時点で、保護膜の構成は、下地からパラジウム１．５μｍ、イリジウム０．５μｍとなった。
【００６７】
これらの金型を洗浄した後、２つの金型の成形面同士を合わせて、酸素濃度が３０ｐｐｍ以下にコントロールされた窒素雰囲気のチャンバー内に入れ、プレス圧力５０ｋｇｆ／ｃｍ^２を加えながら、１２００℃まで加熱し、この状態を１４時間保持した。
【００６８】
こうして作製した金型２個の表面粗さを測定したが、アニール前の表面粗さ０．６ｎｍを保っていた。
【００６９】
その後、前述の条件下でプレス成形を１０００ショット繰り返したが、離型性の悪化は認められなかった。また、金型の表面粗さも、アニール後（成形前）の粗さである、０．６ｎｍを保っていた。
【００７０】
（比較例１）
直径１１０ｍｍの円柱の超硬合金（ＷＣ−Ｃｏ）製の金型母材に、接着層としてタンタル約０．５μｍを高周波スパッタ法にて形成した後、同じく高周波スパッタ法にて、イリジウム−ロジウム（Ｉｒ９５Ｒｈ５（原子％））の保護膜を３μｍ形成した。その後、この金型２個を表面粗さ（Ｒａ）が０．６ｎｍになるよう、研磨（ラップ）加工を施した。このときの研磨量は約１μｍであった。加圧熱処理は施さなかった。
【００７１】
これらの金型を洗浄した後、上記条件下でプレス成形を１０００ショット繰り返したが、離型性の悪化は認められなかった。しかし、金型の表面粗さは５．５ｎｍに悪化した。
【００７２】
（比較例２）
直径１１０ｍｍの円板状の炭化珪素（ＳｉＣ）製の金型母材に、接着層としてタンタル約０．５μｍを高周波スパッタ法にて形成した後、同じく高周波スパッタ法にて、まず第１の保護膜としてパラジウムを１．５μｍ形成し、続いて第２の保護膜としてイリジウムを１．５μｍ形成した。その後、この金型２個を表面粗さ（Ｒａ）が０．６ｎｍになるよう、研磨（ラップ）加工を施した。このときの研磨量は約１μｍであった。この時点で、保護膜の構成は、下地からパラジウム１．５μｍ、イリジウム０．５μｍとなった。加圧熱処理は施さなかった。
【００７３】
これらの金型を洗浄した後、上記条件下でプレス成形を１０００ショット繰り返したが、離型性の悪化は認められなかった。しかし、金型の表面粗さは４．０ｎｍに悪化した。
【００７４】
（比較例３）
直径１１０ｍｍの円柱の超硬合金（ＷＣ−Ｃｏ）製の金型母材に、接着層としてタンタル約０．５μｍを高周波スパッタ法にて形成した後、同じく高周波スパッタ法にて、イリジウム−レニウム（Ｉｒ６０Ｒｅ４０（原子％））の保護膜を３μｍ形成した。その後、２つの金型の成形面同士を合わせて、酸素濃度が３０ｐｐｍ以下にコントロールされた窒素雰囲気のチャンバー内に入れ、プレス圧力５０ｋｇｆ／ｃｍ^２を加えながら、７００℃まで加熱し、この状態を２５時間保持した。このとき、金型の表面粗さ（Ｒａ）は２．０ｎｍであった。
【００７５】
さらに、この金型２個を表面粗さ（Ｒａ）が０．６ｎｍになるよう、研磨（ラップ）加工を施した。このときの研磨量は約１μｍであった。加圧熱処理を先にし、研磨を後にした点が実施例と異なる。
【００７６】
これらの金型を洗浄した後、表面を光学顕微鏡で観察した結果、無数の傷（スクラッチ）が見られ、その深さを測ると０．５μｍ前後であった。この金型では所望の基板品質が得られないため、実際の成形は行わなかった。
【００７７】
【発明の効果】
以上のように本発明によれば、圧力を印加しながら熱処理を施す状態を所定時間保持する加圧熱処理により、保護膜における構成元素の粒成長や拡散現象に起因する面精度の劣化（面荒れ）を抑制しつつ、保護膜を熱的に安定な状態に遷移させることができる。換言すれば、熱処理前に持っていた高い面精度を保ちつつ、熱的安定状態に達した保護膜を得ることができる。このように粒成長や拡散現象に起因する面精度の劣化を防止しながら熱的安定状態に達した保護膜は、もはや、成形時の加熱によっては表面状態は変化しないものになっている。さらに、イリジウム系の貴金属合金を保護膜としているので、他の貴金属系の保護膜に比べて硬度が高く、繰り返し成形に対する表面防傷性が良好である。この表面精度が高く安定した保護膜を有する成形用金型は、高温条件下で繰り返し行われるプレス成形を良好に行うことができる。すなわち、本発明によれば、保護膜の表面精度が長期間にわたって劣化しない成形用金型を提供できる。
【図面の簡単な説明】
【図１】本発明の実施の形態１における成形用金型の加圧熱処理の様子を示す断面図
【図２】本発明の実施の形態２における成形用金型の加圧熱処理の様子を示す断面図
【図３】本発明の実施の形態２の変形の実施の形態を示す金型構成の断面図
【図４】本発明による成形用金型を用いたガラス基板に対するプレス成形の工程を示す断面図
【符号の説明】
１　成形用金型
２　金型母材
３　保護膜
３ａ　第１の保護膜
３ｂ　第２の保護膜
４　ベース材
５　ガラスプリフォーム
５′　ガラス成形品[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a molding die mainly made of glass, more specifically, a molding die having a protective film of an iridium-based noble metal alloy as a protective film of a mold base material, and a method of manufacturing the molding die. About. The molding die according to the present invention exhibits an excellent effect when the molding target is a glass substrate of an information recording medium.
[0002]
[Prior art]
In recent years, there has been an increasing need for miniaturization and large capacity of a magnetic disk substrate, which is an example of an information recording medium, and a glass substrate that has high rigidity, high strength, and is easy to smooth in place of a conventional aluminum substrate. Has been adopted. In such a case, there is a trend to divert the technology of the press molding method in the field of the production of optical elements, instead of the polishing method which is low in productivity and expensive. The press molding method involves transferring the smooth molding surface of the mold to the glass material with high precision by passing through the steps of heating, softening, pressing and cooling the glass material. No polishing is required. Therefore, it is inexpensive and has high productivity in addition to high quality. The press molding method has already been put to practical use in the field of optical element manufacturing. However, even if it is simply applied to a glass substrate for an information recording medium such as a magnetic disk as it is, it can be made smaller, thinner, and has a higher recording density. In fact, it is difficult to obtain sufficiently desirable results in terms of reliability and high reliability.
[0003]
As a molding die used for press molding, there has been proposed a molding die provided with a carbon coat which is considered to have high adhesion to a pressed surface of a mold base material (JP-A-7-10561, JP-A-7-10561). No. 9-194227). However, according to the study of the present inventors, the mold for forming a carbon coat has the following disadvantages.
[0004]
(1) As the molding is repeated, carbon is detached from the protective film to form fine particles. These particles adhere to the glass substrate, causing deterioration of the surface accuracy of the substrate.
[0005]
(2) When the temperature during molding exceeds 600 ° C., even in a nitrogen atmosphere, a trace amount of oxygen remaining in the molding chamber reacts with carbon to generate carbon dioxide. As a result, the carbon film is gradually eroded.
[0006]
(3) Some glass materials can be formed at a low temperature of 600 ° C. or lower. However, glass substrates for magnetic disks are extremely demanding in terms of mechanical strength and the amount of alkali components eluted, and are difficult to cope with.
[0007]
On the other hand, as a mold for an optical element, there has been proposed a molding mold in which a molding surface is coated with a noble metal such as iridium, gold, or platinum, or an alloy containing the same (Japanese Patent Laid-Open Nos. 5-178627 and 5-178627). 8-143320). Above all, since the protective film of an iridium-based noble metal alloy has higher hardness than other noble metal-based protective films, the surface is hardly damaged by repeated molding, and it can be expected to secure surface accuracy for a long time.
[0008]
[Problems to be solved by the invention]
We have further studied the protective film of an iridium-based noble metal alloy, which is one of the most excellent protective film materials as described above. Molding molds with a protective film of an iridium-based noble metal alloy maintain extremely high surface smoothness and flatness in the initial stage, but as the press forming is repeated, the surface smoothness gradually increases in the order of nm. Deterioration progresses to flatness. After investigating the cause, it was clarified that the following phenomena occurred. That is, since the iridium-based noble metal alloy has a high melting point, the film does not reach a thermally stable state immediately after the film is formed by, for example, a sputtering method. It is considered that the internal state transitions toward a thermally stable state even during repeated press molding at a high temperature. As a result, the surface accuracy deteriorates, which is considered to be caused by the diffusion phenomenon of the constituent elements and the grain growth inside the protective film, and a predetermined surface quality cannot be obtained.
[0009]
Incidentally, in order to solve this inconvenience, there is a method in which annealing is performed to obtain a thermally stable state before the mold is subjected to press molding. However, simply performing annealing degrades surface accuracy during annealing.
[0010]
Furthermore, a method of recovering the surface accuracy by polishing the annealed surface having deteriorated surface accuracy may be considered. However, as a result of our study, the surface of the film after annealing is more susceptible to scratches (scratches) during polishing than the surface before annealing (it is thought to be due to the diamond abrasive grains contained in the polishing material). Surface quality cannot be ensured.
[0011]
The present invention has been made in view of such circumstances, and assuming a molding die having a protective film of an iridium-based noble metal alloy, the surface smoothness and flatness deteriorate even after repeated press molding. An object of the present invention is to provide a molding die capable of maintaining a high-quality surface state for a long period of time without performing the same.
[0012]
[Means for Solving the Problems]
In order to solve the above problems, the present invention employs the following means for a molding die. In other words, it is assumed that the protective film formed on the press surface side of the base material of the mold is made of a material mainly containing iridium (Ir). Preferred as the base material is a base material made of a material mainly containing cemented carbide, sapphire or silicon carbide. The protective film is made of not only iridium but also a material containing iridium as a main material and further containing one or more noble metal elements. Preferred as the noble metal element is at least one element selected from the group consisting of rhodium (Rh), ruthenium (Ru), palladium (Pd) and rhenium (Re). Arbitrary plural elements from these groups may be combined. Then, in order to stabilize the film properties of the protective film made of iridium and a noble metal element, a heat treatment is performed at a predetermined temperature range while applying a predetermined pressure for pressing the protective film against the base material for a predetermined time. (Pressure heat treatment) to obtain a molding die.
[0013]
In short, the molding die of the present invention has a base material and a protective film formed on the pressed surface side of the base material, and the protective film further includes iridium (Ir) as a main material. The protective film is made of a material containing at least one kind of noble metal element, and the protective film is subjected to a pressure heat treatment. It is characterized in that a protective film containing iridium as a main material and containing a noble metal element and a pressure heat treatment which is a heat treatment while applying pressure to stabilize the film properties of the protective film are performed.
[0014]
The effect of this is as follows. By applying a pressure heat treatment for maintaining the state of performing the heat treatment while applying pressure for a predetermined time, the protection film is heated while suppressing deterioration of surface accuracy (surface roughness) due to grain growth and diffusion phenomenon of constituent elements in the protection film. It is possible to make a transition to a stable state. The effect of the transition to the thermally stable state in a state where the deterioration of the surface accuracy caused by the grain growth and diffusion phenomenon is suppressed is caused by a simple heat treatment without applying pressure or a polishing treatment subsequent to such a simple heat treatment. This is a unique action that cannot be obtained. It is possible to obtain a protective film that has reached a thermally stable state while maintaining the high surface accuracy that it had before the heat treatment. As described above, the protective film that has reached the thermally stable state while preventing the deterioration of the surface accuracy due to the grain growth and the diffusion phenomenon no longer changes its surface state by heating during molding. Further, since the iridium-based noble metal alloy is used as the protective film, the hardness is higher than that of other noble metal-based protective films, and the surface is resistant to repeated molding. The molding die having a stable protective film having a high surface accuracy can perform the press molding of glass satisfactorily for a long period of time.
[0015]
As another solution, the present invention employs the following means for a molding die. That is, the protective film formed on the press surface side of the base material of the mold is a multilayer protective film of the first protective film and the second protective film. The first protective film is made of a material containing one or more noble metal elements other than iridium. Preferred as the noble metal element is at least one element selected from the group consisting of rhodium (Rh), ruthenium (Ru), palladium (Pd) and rhenium (Re). Arbitrary plural elements from these groups may be combined. The second protective film is made of a material mainly containing iridium. Preferred for the base material is a base material composed of a material containing sapphire or silicon carbide as a main component. Then, in order to stabilize the film properties while changing the first protective film of a noble metal element or its alloy and the second protective film of iridium into an alloy layer, the first and second protective films are kept for a predetermined time. A heat treatment (pressure heat treatment) is performed in a predetermined temperature range while applying a predetermined pressure for pressing the protective film against the base material to obtain a molding die. The reason why the cemented carbide is not mentioned as the base material is as follows. At low temperatures, the processing time is longer for alloying by diffusion of the two protective films. Pressurizing heat treatment at a high temperature is required to perform alloying within a predetermined time range. However, since the cemented carbide has a low heat-resistant temperature, the treatment time is forced to be significantly long, which is not practical.
[0016]
In short, the molding die of the present invention comprises a base material, a first protective film formed on the pressing surface side of the base material, and a second protective film formed on the first protective film. A protective film, wherein the first protective film is made of a material containing at least one noble metal element other than iridium, and the second protective film is made of a material mainly containing iridium (Ir). The first protective film and the second protective film are subjected to a pressure heat treatment.
[0017]
The effect of this is as follows. The first and second protective films are alloyed based on a diffusion phenomenon by a pressurizing heat treatment for maintaining a state of performing the heat treatment while applying a pressure for a predetermined time, but the grain growth of constituent elements in the protective film of the alloy layer is performed. The protective film can be transited to a thermally stable state while suppressing deterioration of surface accuracy (surface roughness) due to the diffusion phenomenon. The effect of the transition to the thermally stable state in a state where the deterioration of the surface accuracy caused by the grain growth and diffusion phenomenon is suppressed is caused by a simple heat treatment without applying pressure or a polishing treatment subsequent to such a simple heat treatment. This is a unique action that cannot be obtained. It is possible to obtain a protective film of an alloy layer that has reached a thermally stable state while maintaining the high surface accuracy that was held before the heat treatment. In this way, the protective layer of the alloy layer, which has reached a thermally stable state while preventing the deterioration of the surface accuracy caused by the grain growth and diffusion phenomenon, no longer changes its surface state by heating during molding. I have. Also, the surface has good scratch resistance against repeated molding. The molding die having the stable and high-precision alloy layer protective film can perform the press molding of glass satisfactorily for a long period of time.
[0018]
Furthermore, since a first protective film of a noble metal element or an alloy thereof and a second protective film of iridium are laminated and then subjected to heat treatment under pressure to form a protective film of an alloy layer, the first protective film also has a second protective film. The protective film also has a high degree of freedom in the composition and composition. In this regard, it is easy to take more appropriate measures to prevent the deterioration of the surface accuracy due to the grain growth and the diffusion phenomenon.
[0019]
In the case of alloying the above-described multilayer protective film, the temperature in the heat treatment under pressure becomes higher than that in the case of the single-layer protective film. Therefore, it is difficult to use a cemented carbide as a base material, and sapphire and silicon carbide are preferable. Incidentally, it may be difficult to obtain sapphire or silicon carbide having a predetermined size. Also, even if available, the price may be high. Therefore, instead of forming the entire base material of sapphire or silicon carbide, a part of the base material is formed of a base material such as cemented carbide, and the base material is formed of a material containing sapphire or silicon carbide as a main component. It is conceivable to form the main part of the preformed base material. By devising in this manner, a base material of a required size can be obtained relatively inexpensively, manufacturing of a molding die becomes easy, and cost can be reduced.
[0020]
Regarding the order of heat treatment for obtaining a thermally stable state and polishing for achieving surface accuracy, polishing is performed first, and pressure heat treatment is performed after polishing. That is, after forming the protective film or the second protective film, the protective film or the second protective film is polished, and then the heat treatment for the protective film or the first and second protective films is performed. Heat treatment accompanied by application (pressure heat treatment) is performed. When polishing is performed after the heat treatment, as described above, scratches are likely to occur during polishing. On the other hand, when pressure heat treatment is performed after polishing as in the present invention, scratches are not substantially generated on the polished surface which is the surface of the protective film or the second protective film. That is, the surface smoothness and flatness are highly excellent.
[0021]
In the above, when the adhesion between the base material and the protective film or the first protective film is insufficient, it is preferable to configure as follows. That is, an adhesive layer such as tantalum (Ta) or chromium (Cr) is formed on the pressed surface side of the base material, and a protective film or a first protective film is formed on the adhesive layer. Thereby, the adhesive force between the base material and the protective film or the first protective film can be enhanced.
[0022]
In the above, it is preferable to set the conditions of the pressure heat treatment as follows.
[0023]
At least one element selected from the group consisting of rhodium, ruthenium, palladium and rhenium is formed on the pressed surface side of a base material made of a material mainly composed of a cemented carbide, with iridium as a main material as a protective film. 10 to 100 kgf / cm when forming a protective film containing ² It is preferable to perform the pressure heat treatment at a temperature in the range of 650 to 750 ° C. for 14 to 50 hours while applying the pressure described above. The temperature is set to 650 to 750 ° C. from the viewpoint of the heat resistance of the base material made of cemented carbide and the processing time. If it exceeds 750 ° C., a problem occurs in heat resistance. If the temperature is lower than 650 ° C., the processing time is disadvantageous.
[0024]
In addition, a protective film containing iridium as a main material and at least one element selected from the group consisting of rhodium, ruthenium, palladium, and rhenium is provided on the pressed surface side of a sapphire or silicon carbide base material. When forming and then performing pressure heat treatment, 10 to 100 kgf / cm ² The pressure heat treatment is preferably performed in a temperature range of 650 to 850 ° C. for 5 to 50 hours while applying the pressure of If the temperature is lower than 650 ° C., the processing time is disadvantageous. Sapphire and silicon carbide have a heat-resistant temperature exceeding 850 ° C., and can be heat-treated at a temperature higher than the above temperature range. However, in the case of a general heat treatment furnace, even if the heat treatment temperature is increased beyond 850 ° C., the overall processing time is not significantly changed in consideration of the increase in the time required for the temperature raising / cooling process. Therefore, the temperature is set to 850 ° C. or less in terms of energy consumption.
[0025]
Regardless of whether the base material is made of cemented carbide, sapphire or silicon carbide, the protective film is heated while suppressing deterioration of surface accuracy (surface roughness) due to grain growth and diffusion of constituent elements in the protective film. In order to make a transition to a stable state, the applied pressure is 10 to 100 kgf / cm. ² It is preferred that 10kgf / cm ² If it is less than 10, it is difficult to suppress the deterioration of the surface accuracy due to the grain growth and diffusion phenomenon. 100kgf / cm ² The effect does not change much even if it exceeds.
[0026]
In addition, a first protective film made of a material containing at least one element selected from the group consisting of rhodium, ruthenium, palladium and rhenium is formed on the pressed surface side of a base material made of sapphire or silicon carbide. Then, if a second protective film made of a material mainly containing iridium is formed on the first protective film, and then pressure heat treatment is performed, 10 to 100 kgf / cm ² It is preferable to perform the pressure heat treatment at a temperature in the range of 1000 to 1400 ° C. for 5 to 50 hours while applying the pressure described above. Since a first protective film of a noble metal element or an alloy thereof and a second protective film of iridium are laminated and then heat-treated under pressure to form a protective film of an alloy layer, both the first protective film and the second protective film are formed. The degree of freedom of the composition is high. In order to make the protective film transition to a thermally stable state while suppressing deterioration of surface accuracy (surface roughness) due to grain growth or diffusion phenomenon of constituent elements in the protective film of the alloy layer, a temperature range is required. 1000-1400 degreeC is preferable. If the temperature is lower than 1000 ° C., the processing time is disadvantageous. It is possible to perform the heat treatment at a temperature higher than the above temperature range. However, in the case of a general heat treatment furnace, even if the heat treatment temperature is increased beyond 1400 ° C., the overall treatment time does not change much, considering the increase in the time required for the temperature raising / cooling process. Therefore, the temperature is set to 1400 ° C. or less in terms of energy consumption.
[0027]
In the above, it is preferable that the pressing surfaces of the pair of molding dies be pressed against each other and pressed against each other as a mode of applying the pressure in the pressure heat treatment. Pressurization heat treatment can be performed on two molding dies at one time, so that work efficiency is high and manufacturing cost can be reduced.
[0028]
As described above, according to the present invention, it is possible to obtain a molding die having excellent surface smoothness and flatness over a long period of time. In particular, when the molding die of the present invention is applied to the molding of a glass substrate of an information recording medium, it exhibits an excellent and great effect, and has excellent surface accuracy even when the glass substrate is repeatedly subjected to press molding under high temperature conditions. A glass substrate can be obtained.
[0029]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of a molding die and a method of manufacturing the same according to the present invention will be described in detail with reference to the drawings.
[0030]
(Embodiment 1)
FIG. 1 is a cross-sectional view showing a state of pressure heat treatment (annealing) of a molding die according to Embodiment 1 of the present invention. Each of the pair of molding dies 1 and 1 shown in FIG. 1 includes a mold base material 2 and a protective film 3. As the mold base material 2, a material composed of a cemented carbide (sintered body of tungsten carbide), sapphire, silicon carbide (SiC), or the like is used. Processing such as cutting and polishing is performed on these materials to obtain a mold base material 2 having a predetermined shape and surface accuracy.
[0031]
The protective film 3 is formed on the base material 2 by using a thin film forming method such as a sputtering method. Here, depending on the type of the base material and the protective film, the adhesive force between them may be insufficient. In that case, an adhesive layer (not shown) of tantalum (Ta), chromium (Cr), or the like is formed as a base layer of the protective film 3.
[0032]
After the protective film 3 is formed, the molding surfaces of the pair of molding dies 1 and 1 are opposed to and opposed to each other as shown in the drawing, and are heated in a heating furnace (not shown) in a range of 10 to 100 kgf / cm. ² Heat treatment is performed while applying a moderate pressure (pressure heat treatment). The heat treatment temperature at this time is preferably higher in order to shorten the processing time, but in consideration of the heat resistance of the base material 2 of the molding die 1, when a cemented carbide is used, 650 to 750 ° C. Is preferred.
[0033]
When sapphire or silicon carbide (SiC) is used for base material 2, a preferable heat treatment temperature is 650 to 850 ° C. Since sapphire and silicon carbide have high heat resistance, it is possible to perform heat treatment at a higher temperature. However, in a general heat treatment furnace, an increase in the time required for the temperature raising / cooling process is large. Therefore, even if the heat treatment temperature is increased beyond 850 ° C., there is almost no effect of reducing the actual processing time. For this reason, the preferred upper temperature limit is set at 850 ° C. If the processing temperature is 800 ° C. or lower, the processing time becomes longer, but the temperature can be raised by a cartridge heater generally used in a molding machine, and the molding machine can be used as a heat treatment furnace. There is an advantage that can be suppressed.
[0034]
By this heat treatment under pressure, the protective film 3 moves to a thermally stable state. At this time, by applying pressure at the same time, it is possible to prevent deterioration of surface accuracy (surface roughness), which is considered to be caused by grain growth or diffusion phenomenon.
[0035]
Thus, it is possible to obtain the protective film 3 that has reached a thermally stable state while maintaining the high surface accuracy that was possessed before the heat treatment. The surface state of the protective film 3 does not change by heating during press molding of the glass substrate. In this way, it is possible to obtain a molding die capable of maintaining a stable surface state and performing good press molding of a glass substrate for a long period of time.
[0036]
(Embodiment 2)
FIG. 2 is a cross-sectional view showing a state of pressure heat treatment of a molding die according to Embodiment 2 of the present invention. The pair of molding dies 1, 1 shown in FIG. 2 includes a base material 2, a first protective film 3a, and a second protective film 3b. The base material 2 is made of sapphire or silicon carbide (SiC) having a desired shape and surface accuracy.
[0037]
First, a first protective film 3a is formed on the base material 2 by using a thin film forming method such as a sputtering method, and then a second protective film 3b is formed. Here, depending on the type of the base material and the film, the adhesive force between them may be insufficient. In that case, an adhesive layer (not shown) of tantalum, chromium, or the like is formed as a base layer of the first protective film 3a.
[0038]
After forming the first protective film 3a and the second protective film 3b, as shown in the figure, the molding surfaces of the pair of molding dies 1, 1 are opposed to and in contact with each other, and are placed in a heating furnace (not shown). , 10-100kgf / cm ² Heat treatment is performed while applying a moderate pressure (pressure heat treatment). By this heat treatment, the constituent particles of the first protective film 3a diffuse into the second protective film 3b, and as a result, an alloy layer (not shown) having a thermally stable state is formed. The heat treatment temperature at this time is preferably from 1000 ° C. to 1400 ° C. The heat treatment time for obtaining a thermally stable state was about 50 hours at 1000 ° C. and about 5 hours at 1400 ° C. The lower limit of the preferred temperature is determined from an appropriate working time. As described in the first embodiment, the upper limit of the preferable temperature is determined because there is almost no effect of reducing the actual processing time.
[0039]
Note that when the diffusion coefficient D of the film is Brian Reed et. al. , Rhenium and Rhenium Alloys p443-457, The Minerals Metals & Materials Society (1997), that is, E = 1.23 (eV), T is temperature (K), k is Boltzmann's constant, and k = 1.38. × 10 ^-23 As J / K,
D = D ₀ ・ Exp (-E / kT)
At a heat treatment temperature of 750 ° C., a heat treatment of 500 hours or more is required. Cemented carbide cannot have a heat treatment temperature higher than 750 ° C. because of its low heat resistance temperature. Therefore, when the protective film has two layers, it is not practical to select a cemented carbide as the material of the base material 2.
[0040]
The first protective film 3a and the second protective film 3b having a two-layer structure by this heat treatment form an alloy layer by a diffusion phenomenon. At this time, by applying pressure, it is possible to prevent deterioration of surface accuracy (surface roughness), which is considered to be caused by grain growth or diffusion phenomenon.
[0041]
In this way, it is possible to obtain an alloy layer that has reached a thermally stable state while maintaining the high surface accuracy that it had before the heat treatment. The surface state of this alloy layer is not changed by heating during press forming of the glass substrate. In this manner, a stable surface state can be maintained, and as a result, a molding die capable of performing press molding on a glass substrate for a long period of time can be obtained.
[0042]
In the above description, regarding sapphire and silicon carbide, a material having a required volume may be difficult to obtain, or even if available, it may be very expensive. In that case, as shown in FIG. 3, a base material 4 made of a cemented carbide or the like may be used. That is, after the first and second

protective films

3a and 3b are formed on the base material 2 made of sapphire or silicon carbide, heat treatment is performed under pressure to form a semi-finished product of a molding die. By fixing the base material 2 of the semi-finished product on the base material 4 described above, it is also possible to form a molding die.
[0043]
【Example】
In order to confirm the effects of the present invention, molding was performed under the following conditions.
[0044]
FIG. 4 shows a process chart of the glass forming method performed this time. As shown in FIG. 4 (A), a pair of molding dies 1, 1 are mounted in a molding apparatus (not shown) such that the molding surfaces which are the surfaces of the

protective films

3, 3 face each other. . A glass preform 5 of aluminosilicate glass having a softening point temperature of 630 ° C. was put on the molding surface of the lower molding die 1. Next, as shown in FIG. 4 (B), the glass preform 5 was pressed by the molding dies 1 and 1 at a high temperature. The pressing conditions at this time were as follows: temperature 620 ° C., pressure 200 kgf / cm at maximum. ² And During the heating, nitrogen gas was kept flowing into the molding apparatus for the purpose of preventing oxidation. Thereafter, as shown in FIG. 4 (C), it was taken out from the molding dies 1, 1 to obtain a glass molded product 5 '.
[0045]
Each of the above processes was performed 1000 times (shots) using the dies shown in the following examples and comparative examples. Table 1 shows the configuration of the mold and the change in the surface state after molding.
[0046]
[Table 1]

[0047]
(Example 1)
After forming about 0.5 μm of tantalum as an adhesive layer on a cylinder base material made of a cemented carbide (WC-Co) having a diameter of 110 mm by a high frequency sputtering method, the iridium-rhodium ( A protective film of Ir95Rh5 (atomic%) was formed at 3 μm. Thereafter, the two molds were polished (wrapped) so that the surface roughness (Ra: center line average roughness) became 0.6 nm. As a result of the polishing, the thickness of the protective film was about 2 μm.
[0048]
After washing these molds, the molding surfaces of the two molds were put together and put into a chamber in a nitrogen atmosphere in which the oxygen concentration was controlled to 30 ppm or less, and the pressing pressure was 50 kgf / cm. ² , And heated to 700 ° C., and this state was maintained for 25 hours.
[0049]
The surface roughness of the two dies thus manufactured was measured, and the surface roughness before annealing was maintained at 0.6 nm.
[0050]
Thereafter, the press molding was repeated 1000 shots under the conditions described above, but the roughness after annealing (before molding) was maintained at 0.6 nm.
[0051]
(Example 2)
After forming about 0.5 μm of tantalum as an adhesive layer on a mold base made of a cemented carbide (WC-Co) having a diameter of 110 mm by a high frequency sputtering method, iridium-ruthenium ( A protective film of Ir90Ru10 (atomic%) was formed at 3 μm. Thereafter, the two molds were polished (wrapped) so that the surface roughness (Ra) became 0.6 nm. As a result of the polishing, the thickness of the protective film was about 2 μm.
[0052]
After washing these molds, the molding surfaces of the two molds were put together and put into a chamber in a nitrogen atmosphere in which the oxygen concentration was controlled to 30 ppm or less, and the pressing pressure was 50 kgf / cm. ² , And heated to 700 ° C., and this state was maintained for 25 hours.
[0053]
The surface roughness of the two dies thus manufactured was measured, and the surface roughness before annealing was maintained at 0.6 nm.
[0054]
Thereafter, the press molding was repeated 1000 shots under the conditions described above, but the roughness after annealing (before molding) was maintained at 0.6 nm.
[0055]
(Example 3)
After forming about 0.5 μm of tantalum as an adhesive layer on a mold base material made of a cemented carbide (WC-Co) having a diameter of 110 mm by a high frequency sputtering method, the iridium-palladium ( A protective film of Ir98Pd2 (atomic%) was formed at 3 μm. Thereafter, the two molds were polished (wrapped) so that the surface roughness (Ra) became 0.6 nm. As a result of the polishing, the thickness of the protective film was about 2 μm.
[0056]
After washing these molds, the molding surfaces of the two molds were put together and put into a chamber in a nitrogen atmosphere in which the oxygen concentration was controlled to 30 ppm or less, and the pressing pressure was 50 kgf / cm. ² , And heated to 700 ° C., and this state was maintained for 25 hours.
[0057]
The surface roughness of the two dies thus manufactured was measured, and the surface roughness before annealing was maintained at 0.6 nm.
[0058]
Thereafter, the press molding was repeated 1000 shots under the conditions described above, but the roughness after annealing (before molding) was maintained at 0.6 nm.
[0059]
(Example 4)
After forming about 0.5 μm of tantalum as an adhesive layer on a mold base material made of a cemented carbide (WC-Co) having a diameter of 110 mm by a high frequency sputtering method, the iridium-rhenium ( A protective film of Ir60Re40 (atomic%) was formed at 2 μm. Thereafter, the molding surfaces of the two molds were put together and put into a chamber in a nitrogen atmosphere in which the oxygen concentration was controlled to 30 ppm or less, and the pressing pressure was 50 kgf / cm. ² , And heated to 700 ° C., and this state was maintained for 25 hours. No polishing (lapping) was performed.
[0060]
The surface roughness of the two dies thus manufactured was measured, and the surface roughness before annealing was maintained at 2.0 nm.
[0061]
Thereafter, the press molding was repeated 1000 shots under the above conditions, but the roughness after annealing (before molding) was maintained at 2.0 nm.
[0062]
(Example 5)
About 0.5 μm of tantalum is formed as an adhesive layer on a cylindrical base material of sapphire (single crystal alumina) having a diameter of 110 mm by high frequency sputtering, and then the first protective film is also formed by high frequency sputtering. Then, rhenium was formed in a thickness of 1.5 μm, and then iridium was formed in a thickness of 1.5 μm as a second protective film. Thereafter, the two molds were polished (wrapped) so that the surface roughness (Ra) became 0.6 nm. The polishing amount at this time was about 1 μm. At this point, the composition of the protective film was 1.5 μm rhenium and 0.5 μm iridium from the base.
[0063]
After washing these molds, the molding surfaces of the two molds were put together and put into a chamber in a nitrogen atmosphere in which the oxygen concentration was controlled to 30 ppm or less, and the pressing pressure was 50 kgf / cm. ² Was added to the mixture and heated to 1200 ° C., and this state was maintained for 14 hours.
[0064]
The surface roughness of the two dies thus manufactured was measured, and the surface roughness before annealing was maintained at 0.6 nm.
[0065]
Thereafter, the press molding was repeated 1000 shots under the conditions described above, but the roughness after annealing (before molding) was maintained at 0.6 nm.
[0066]
(Example 6)
After forming about 0.5 μm of tantalum as an adhesive layer on a disk-shaped mold base made of silicon carbide (SiC) having a diameter of 110 mm by high-frequency sputtering, the first protection is also performed by high-frequency sputtering. As a film, 1.5 μm of palladium was formed, followed by 1.5 μm of iridium. Thereafter, the two molds were polished (wrapped) so that the surface roughness (Ra) became 0.6 nm. The polishing amount at this time was about 1 μm. At this point, the configuration of the protective film was 1.5 μm of palladium and 0.5 μm of iridium from the base.
[0067]
After washing these molds, the molding surfaces of the two molds were put together and put into a chamber in a nitrogen atmosphere in which the oxygen concentration was controlled to 30 ppm or less, and the pressing pressure was 50 kgf / cm. ² Was added to the mixture and heated to 1200 ° C., and this state was maintained for 14 hours.
[0068]
The surface roughness of the two dies thus manufactured was measured, and the surface roughness before annealing was maintained at 0.6 nm.
[0069]
Thereafter, the press molding was repeated 1,000 shots under the conditions described above, but no deterioration in the releasability was observed. Also, the surface roughness of the mold was maintained at 0.6 nm, which is the roughness after annealing (before molding).
[0070]
(Comparative Example 1)
After forming about 0.5 μm of tantalum as an adhesive layer on a cylinder base material made of a cemented carbide (WC-Co) having a diameter of 110 mm by a high frequency sputtering method, the iridium-rhodium ( A protective film of Ir95Rh5 (atomic%) was formed at 3 μm. Thereafter, the two molds were polished (wrapped) so that the surface roughness (Ra) became 0.6 nm. The polishing amount at this time was about 1 μm. No pressure heat treatment was applied.
[0071]
After washing these molds, press molding was repeated 1,000 times under the above-mentioned conditions, but no deterioration in releasability was observed. However, the surface roughness of the mold deteriorated to 5.5 nm.
[0072]
(Comparative Example 2)
After forming about 0.5 μm of tantalum as an adhesive layer on a disk-shaped mold base made of silicon carbide (SiC) having a diameter of 110 mm by high-frequency sputtering, the first protection is also performed by high-frequency sputtering. 1.5 μm of palladium was formed as a film, and then 1.5 μm of iridium was formed as a second protective film. Thereafter, the two molds were polished (wrapped) so that the surface roughness (Ra) became 0.6 nm. The polishing amount at this time was about 1 μm. At this point, the configuration of the protective film was 1.5 μm of palladium and 0.5 μm of iridium from the base. No pressure heat treatment was applied.
[0073]
After washing these molds, press molding was repeated 1,000 times under the above-mentioned conditions, but no deterioration in releasability was observed. However, the surface roughness of the mold deteriorated to 4.0 nm.
[0074]
(Comparative Example 3)
After forming about 0.5 μm of tantalum as an adhesive layer on a mold base material made of a cemented carbide (WC-Co) having a diameter of 110 mm by a high frequency sputtering method, the iridium-rhenium ( A protective film of Ir60Re40 (atomic%) was formed at 3 μm. Thereafter, the molding surfaces of the two molds were put together and put into a chamber in a nitrogen atmosphere in which the oxygen concentration was controlled to 30 ppm or less, and the pressing pressure was 50 kgf / cm. ² , And heated to 700 ° C., and this state was maintained for 25 hours. At this time, the surface roughness (Ra) of the mold was 2.0 nm.
[0075]
Further, the two molds were polished (wrapped) so that the surface roughness (Ra) became 0.6 nm. The polishing amount at this time was about 1 μm. The difference from the embodiment is that the pressure heat treatment is performed first and the polishing is performed after.
[0076]
After cleaning these molds, the surface was observed with an optical microscope. As a result, countless scratches (scratches) were observed, and the depth was about 0.5 μm. Since the desired substrate quality could not be obtained with this mold, actual molding was not performed.
[0077]
【The invention's effect】
As described above, according to the present invention, deterioration in surface accuracy (surface roughness) due to grain growth and diffusion of constituent elements in the protective film is caused by pressurized heat treatment for maintaining a state of performing heat treatment while applying pressure for a predetermined time. ), The protective film can be transitioned to a thermally stable state. In other words, it is possible to obtain a protective film that has reached a thermally stable state while maintaining the high surface accuracy that it had before the heat treatment. As described above, the protective film that has reached the thermally stable state while preventing the deterioration of the surface accuracy due to the grain growth and the diffusion phenomenon no longer changes its surface state by heating during molding. Further, since the iridium-based noble metal alloy is used as the protective film, the hardness is higher than that of other noble metal-based protective films, and the surface is resistant to repeated molding. The molding die having a stable protective film having a high surface accuracy can satisfactorily perform press molding repeatedly performed under high temperature conditions. That is, according to the present invention, it is possible to provide a molding die in which the surface accuracy of the protective film does not deteriorate over a long period of time.
[Brief description of the drawings]
FIG. 1 is a sectional view showing a state of a pressure heat treatment of a molding die according to a first embodiment of the present invention.
FIG. 2 is a sectional view showing a state of a pressure heat treatment of a molding die according to a second embodiment of the present invention.
FIG. 3 is a cross-sectional view of a mold configuration showing a modified embodiment of the second embodiment of the present invention.
FIG. 4 is a cross-sectional view showing a step of press-molding a glass substrate using a molding die according to the present invention.
[Explanation of symbols]
1 Mold for molding
2 Mold base material
3 Protective film
3a First protective film
3b Second protective film
4 Base material
5 Glass preform
5 'glass molded product

Claims

A base material, and a protective film formed on the pressed surface side of the base material, wherein the protective film is made of a material containing iridium (Ir) as a main material and further containing one or more noble metal elements; Molding mold with protective heat treatment applied to the protective film.

The molding material according to claim 1, wherein the noble metal element in the protective film is at least one element selected from the group consisting of rhodium (Rh), ruthenium (Ru), palladium (Pd), and rhenium (Re). Mold.

3. The molding die according to claim 1, wherein the base material is made of a material containing cemented carbide, sapphire, or silicon carbide as a main component. 4.

4. The pressure heat treatment according to claim 1, wherein the heat treatment is performed in a predetermined temperature range while applying a predetermined pressure for pressing the protective film against the base material for a predetermined time. The molding die described in the above.

The molding die according to claim 1, wherein a surface of the protective film is a polished surface.

The molding die according to any one of claims 1 to 5, wherein the base material and the protective film have an adhesive layer such as tantalum (Ta) or chromium (Cr) interposed therebetween.

A base material, a first protective film formed on the pressing surface side of the base material, and a second protective film formed on the first protective film, wherein the first protective film Is made of a material containing one or more noble metal elements other than iridium, the second protective film is made of a material mainly containing iridium (Ir), and the first protective film and the second protective film Molding mold in which the film is subjected to pressure heat treatment.

8. The noble metal element in the first protective film is at least one element selected from the group consisting of rhodium (Rh), ruthenium (Ru), palladium (Pd), and rhenium (Re). Mold for molding.

The molding die according to claim 7, wherein the base material is made of a material containing sapphire or silicon carbide as a main component.

8. The base material comprises a base material such as a cemented carbide, and a base material main portion formed on the base material and composed of a material mainly containing sapphire or silicon carbide. A molding die according to claim 8.

8. The heat treatment under pressure in a predetermined temperature range while applying a predetermined pressure for pressing the first protective film and the second protective film against the base material for a predetermined time. The molding die according to any one of claims 1 to 10.

The molding die according to any one of claims 7 to 11, wherein a surface of the second protective film is a polished surface.

13. The molding metal according to claim 7, wherein the base material and the first protective film have an adhesive layer such as tantalum (Ta) or chromium (Cr) interposed therebetween. Type.

The molding die according to any one of claims 1 to 13, which is used for molding a glass substrate of an information recording medium.

A protective film made of iridium (Ir) as a main material and further containing one or more noble metal elements is formed on the pressing surface side of the base material, and the protective film is pressed against the base material for a predetermined time. A method for producing a molding die, wherein a pressure heat treatment for performing a heat treatment in a predetermined temperature range while applying a pressure is performed to produce a molding die.

A base material made of a material mainly containing cemented carbide, sapphire or silicon carbide is used as the base material, and iridium (Ir) is used as a main material as the protective film, and rhodium (Rh), ruthenium (Ru), The method for manufacturing a molding die according to claim 15, wherein a protective film containing at least one element selected from the group consisting of palladium (Pd) and rhenium (Re) is used.

Prior to forming the protective film on the pressed surface side of the base material, an adhesive layer such as tantalum (Ta) or chromium (Cr) is formed on the pressed surface of the base material. The method according to claim 15, wherein the protective film is formed thereon.

The method for manufacturing a molding die according to any one of claims 15 to 17, wherein a surface of the formed protective film is polished between the formation of the protective film and the pressure heat treatment.

19. When the base material made of a cemented carbide is used as the base material, the pressure heat treatment is performed under the conditions of 10 to 100 kgf / cm ² , 650 to 750 ° C., and 14 to 50 hours. A method for producing a molding die according to any one of the above.

19. When the base material made of sapphire or silicon carbide is used as the base material, the pressure heat treatment is performed under the conditions of 10 to 100 kgf / cm ² , 650 to 850 ° C., and 5 to 50 hours. The method for producing a molding die according to any one of the above.

A first protective film made of a material containing at least one element selected from the group consisting of rhodium (Rh), ruthenium (Ru), palladium (Pd), and rhenium (Re) on the pressed surface side of the base material Is formed, and then a second protective film made of a material mainly containing iridium (Ir) is formed on the first protective film, and the first protective film and the second protective film are formed for a predetermined time. A method for manufacturing a molding die, wherein a pressure heat treatment is performed in a predetermined temperature range while applying a predetermined pressure for pressing the protective film against the base material.

The method for manufacturing a molding die according to claim 21, wherein a base material made of a material mainly containing sapphire or silicon carbide is used as the base material.

Prior to forming the first protective film on the pressed surface side of the base material, an adhesive layer such as tantalum (Ta) or chromium (Cr) is formed on the pressed surface of the base material. The method for manufacturing a molding die according to claim 21, wherein the first protective film is formed on an adhesive layer.

24. The molding die according to claim 21, wherein the surface of the formed second protective film is polished between the formation of the second protective film and the pressure heat treatment. Manufacturing method.

The heat treatment under pressure is performed under the conditions of 10 to 100 kgf / cm ² , 1000 to 1400 ° C., and 5 to 50 hours when a sapphire or silicon carbide base material is used as the base material. The method for producing a molding die according to any one of the above.

The molding die according to any one of claims 15 to 25, wherein the pressure heat treatment is performed by pressing the pair of molding dies against each other and pressing each other against each other. Manufacturing method.