JP2004000383A

JP2004000383A - Lead-free heat generation film for electromagnetic cooker, and container for electromagnetic cooker

Info

Publication number: JP2004000383A
Application number: JP2002186675A
Authority: JP
Inventors: Masahito Suzuki; 鈴木　雅人; Shirohito Matsuyama; 松山　城仁
Original assignee: Narumi China Corp
Current assignee: Narumi China Corp
Priority date: 2002-04-26
Filing date: 2002-06-26
Publication date: 2004-01-08

Abstract

<P>PROBLEM TO BE SOLVED: To provide a lead-free heat generation film for an electromagnetic cooker and a container for electromagnetic cooking which contain no lead and can be used also for the high power electromagnetic cooker. <P>SOLUTION: The lead-free heat generation film 1 for the electromagnetic cooker is stuck to a container and baked to make the container for electromagnetic cooking with which electromagnetic cooking can be performed. The lead-free heat generation film 1 has a metal composition layer 15 for heat generation on the side of its rear surface and has a lead-free coating glass composition layer 152 laminated on the side of its front surface. The metal composition layer 15 consists of a mixture of metal made of gold, silver and platinum, lead-free glass and an organic binder. The mixing ratio of the metal and the lead-free glass is 85 to 99 pts.wt. of metal to 1 to 15 pts.wt. of lead-free coating glass based on 100 pts.wt. of them. The lead-free glass and the coating glass composition layer have a 550 to 700°C transition point and 650 to 750°C deformation temperature. <P>COPYRIGHT: (C)2004,JPO

Description

【０００１】
【技術分野】
本発明は，高出力の電磁調理器に対応した電磁調理用無鉛発熱膜及び電磁調理用容器に関する。
【０００２】
【従来技術】
従来より，電磁調理器は，その高い安全性によりガスコンロに代わる調理器として広く普及してきた。上記電磁調理器は電磁誘導を利用して，電磁調理器上に設置した電磁調理用容器に表皮効果による発熱を引き起こし，加熱するものである。また，近年になって，さらに高い出力を有する２００Ｖ対応の電磁調理器が急速に普及している。
【０００３】
電磁調理器に使用できる上記電磁調理用容器は，原則として磁性金属又は電磁誘導による表皮効果を利用して実効抵抗が４〜２０×１０^−４Ωとなる導電体であった。そのため，アルミ，銅，又はセラミックスからなる鍋等の調理器は，電磁調理器にて発熱させることができないという問題があった。
【０００４】
そこで，セラミックスからなる調理器を電磁調理器にて発熱させるために，低熱膨張素地からなる調理器の底に金，銀，白金からなる発熱体膜を張る方法が開発されている（実公昭５９−１１４３６）。上記発熱体膜は結合ガラス層によって接合された金属層と，該金属層を保護するためのガラスコート層からなっている。上記発熱膜にて表面を被覆した調理器は，上記発熱膜が表皮効果により発熱するため，電磁調理器にて使用可能となる。
【０００５】
【解決しようとする課題】
しかしながら，上記発熱体膜は，９００℃以下の温度で焼成したときに充分な密着強度を保持することができるように，上記金属層またはガラスコート層に転移点が５００℃未満，屈伏点が６５０℃未満の低融点有鉛ガラスを含有している。そのため，上記発熱体膜で被覆した調理器を，例えば２００Ｖ対応の高出力電磁調理器にて発熱させると，発熱体膜の表面温度が５００℃付近まで上昇する場合があり，発熱体膜中のガラス成分が軟化又は再溶融し，使用中に断線等の不具合を生じるという問題があった。
【０００６】
また，上記発熱膜は，上記調理器の内側に被覆すると，調理器内部の食材等を効率的に加熱することができる。しかし，上記発熱体膜はそのガラス成分中に人体に有害な鉛を含んでいるため，調理器内部に被覆することが困難であるという問題があった。
【０００７】
本発明は，かかる従来の問題点に鑑みてなされたもので，鉛を含有せず，高出力の電磁調理器においても使用することができる電磁調理用無鉛発熱膜及び電磁調理用容器を提供しようとするものである。
【０００８】
【課題の解決手段】
第１の発明は，容器に貼着し焼成して電磁調理可能な電磁調理用容器とするための電磁調理用無鉛発熱膜であって，
上記電磁調理用無鉛発熱膜は，裏面側に発熱用金属組成物層を有し，その表面側には，無鉛被覆ガラス組成物層を積層してなり，
上記発熱用金属組成物層は，金，銀，又は白金からなる金属と無鉛ガラスと有機バインダーとの混合物よりなり，
上記金属と無鉛ガラスとの混合割合は，両者を１００重量部としたとき，金属が８５〜９９重量部で，無鉛ガラスが１〜１５重量部であり，
上記無鉛ガラス及び無鉛被覆ガラス組成物層は，転移点が５５０℃〜７００℃であり，かつ屈伏点が６５０℃〜７５０℃であることを特徴とする電磁調理用無鉛発熱膜にある（請求項１）。
【０００９】
本発明において，上記電磁調理用無鉛発熱膜は，金，銀，又は白金からなる金属と無鉛ガラスと有機バインダーとの混合物よりなる発熱用金属組成物層を有している。そのため，電磁調理用無鉛発熱膜を容器に貼着し焼成すると，該容器は，電磁調理が可能な電磁調理用容器となる。
【００１０】
また，上記無鉛ガラス及び無鉛被覆ガラス組成物層は，転移点が５５０℃〜７００℃であり，かつ屈伏点が６５０℃〜７５０℃である。
そのため，上記電磁調理用無鉛発熱膜を貼着し焼成した電磁調理用容器は，例えば２００Ｖ対応の高出力な電磁調理器においても使用することができる。上記のように５５０℃〜７００℃という高い転移点及び６５０℃〜７５０℃という高い屈伏点を有する，焼成後の無鉛ガラス及び無鉛被覆ガラス組成物層は，高出力の電磁調理器にて使用しても，再溶融することがないからである。
【００１１】
また，上記電磁調理用無鉛発熱膜は，容器に貼着する裏面側に発熱用金属組成物層を有し，その表面側には，無鉛被覆ガラス組成物層を積層してなる。
そのため，上記電磁調理用無鉛発熱膜を容器に貼着し焼成すると，焼成後の上記発熱用金属組成物層の表面は，焼成後の上記無鉛被覆ガラス組成物層にて覆われる。そのため，焼成後の上記発熱用金属組成物層が他の物質と直に接することがなく，摩擦などにより焼成後の発熱用金属組成物層が劣化することがない。
【００１２】
また，上記金属と無鉛ガラスとの混合割合は，両者を１００重量部としたとき，金属が８５〜９９重量部で，無鉛ガラスが１〜１５重量部である。
そのため，上記電磁調理用無鉛発熱膜は，焼成時には上記無鉛ガラスが溶融し容器と充分に密着することができ，焼成後には上記容器の表面に焼き付けられた金属が電磁調理器等の誘導加熱によって充分に発熱することができる。
【００１３】
また，上記電磁調理用無鉛発熱膜は，無鉛ガラス及び無鉛被覆ガラス組成物層を含有しており，組成物中に人体に有害な鉛を含有していない。そのため，上記電磁調理用無鉛発熱膜を容器の内側に貼着することができる。
【００１４】
このように，本発明によれば，鉛を含有せず，高出力の電磁調理器においても使用することができる電磁調理用無鉛発熱膜を提供することができる。
【００１５】
第２の発明は，容器の表面に無鉛発熱膜を形成してなる電磁調理用容器であって，
上記無鉛発熱膜は，容器側に接合形成した発熱金属層と，該発熱金属層の表面に設けた無鉛被覆ガラス層とよりなり，
上記発熱金属層は，金，銀，又は白金よりなる金属８５〜９９重量部と，無鉛ガラス１〜１５重量部とからなり，
上記無鉛ガラス及び無鉛被覆ガラス層は，転移点が５５０℃〜７００℃であり，かつ屈伏点が６５０℃〜７５０℃であることを特徴とする電磁調理用容器にある（請求項５）。
【００１６】
本発明において，上記電磁調理用容器は，容器の表面に発熱用金属層を有しているため，電磁誘導による表皮効果により発熱用金属層が発熱し，電磁調理が可能である。
また，上記発熱用金属層は，金，銀又は白金よりなる金属８５〜９９重量部と，無鉛ガラス１〜１５重量部とからなる。そのため，上記発熱用金属層は，連続した層を形成し，電磁調理により充分に発熱することができる共に，容器と密着性良く密着している。
【００１７】
また，上記発熱用金属層の表面には無鉛被覆ガラス層が設けられており，両者は連続した層を形成している。そのため，上記発熱用金属層は上記無鉛被覆ガラス層によって保護され耐久性に優れている。さらに，上記無鉛被覆ガラス層は，発熱用金属層を被覆して，該発熱用金属層を容器の表面に密着性良く密着させている。
【００１８】
また，上記無鉛ガラス及び無鉛被覆ガラス層は，５５０℃〜７００℃という高い転移点及び６５０℃〜７５０℃という高い屈伏点を有している。
そのため，上記電磁調理用容器は，使用中に上記無鉛ガラス及び無鉛被覆ガラス層が再溶融することはほとんどなく，例えば２００Ｖ対応の高出力な電磁調理器にて使用ができる。
【００１９】
また，上記無鉛発熱膜は，無鉛ガラス及び無鉛被覆ガラス層を含有しており，組成物中に人体に有害な鉛を含有していない。そのため，安全性に優れている。
【００２０】
このように，本発明によれば，鉛を含有せず，高出力の電磁調理器においても使用することができる電磁調理用容器を提供することができる。
【００２１】
【発明の実施の形態】
上記第１の発明（請求項１）においては，上記金属と無鉛ガラスとの混合割合は，両者を１００重量部としたとき，金属が８５〜９９重量部で，無鉛ガラスが１〜１５重量部である。
上記金属が８５重量部未満の場合，又は無鉛ガラスが１５重量部を超える場合には，焼成後の上記電磁調理用無鉛発熱膜を充分に発熱させることができない。一方，上記金属が９９重量部を超える場合，又は無鉛ガラスが１重量％未満の場合には，上記電磁調理用無鉛発熱膜と容器とが充分に密着し難くなり，焼成後に剥がれを生じ易くなる。
【００２２】
上記混合割合のさらに好ましい範囲は，両者を１００重量部としたとき，金属が９０〜９５重量部で，無鉛ガラスが５〜１０重量部である。
この場合には，焼成後の電磁調理用無鉛発熱膜の発熱性を一層向上させることができる。
【００２３】
また，上記無鉛ガラス及び無鉛被覆ガラス組成物層は，転移点が５５０℃〜
７００℃であり，かつ屈伏点６５０℃〜７５０℃である。上記転移点が５５０℃未満の場合または屈伏点が６５０℃未満の場合には，焼成後の無鉛ガラス及び無鉛被覆ガラス組成物層が再溶融し易いため，例えば２００Ｖという高出力の電磁調理器に使用することができない。一方，上記転移点が７００℃を超える場合または屈伏点が７５０℃を超える場合には，上記転移点及び屈伏点が高すぎて，焼成が困難になり，焼成後の上記電磁調理用無鉛発熱膜が剥がれ易くなる。
【００２４】
また，上記電磁調理用無鉛発熱膜は，容器の内側又は外側に貼着することができる。好ましくは，内側に貼着するのがよい。この場合には，容器の内側が発熱する電磁調理用容器を作製することができ，容器内の食材等を効率的に加熱することができる。
【００２５】
また，上記有機バインダーは，上記金属と無鉛ガラスとの混合物１００重量部に対して，２０〜１００重量部含有させることができる。上記有機バインダーの含有量が２０重量部未満の場合には，例えばスクリーン印刷にて上記発熱用金属組成物層を形成するときに，均一な形状及び厚みに形成することが困難になるおそれがある。一方，１００重量部を超える場合には，焼成後に有機バインダーが残存し，焼成後の上記電磁調理用無鉛発熱膜がちぢれ易くなるおそれがある。
【００２６】
また，上記有機バインダーとしては，例えばアクリル系樹脂，アルキッド系樹脂，ブチル樹脂，エチルセルロース系樹脂，ニトロセルロース系樹脂，メチルセルロース系樹脂等を用いることができる。
【００２７】
また，上記無鉛被覆ガラス組成物層には，無機顔料を含有させることができる。この場合には，焼成後の上記無鉛被覆ガラス組成物層に色彩を与えることができる。ここで，上記無機顔料の含有量は，無鉛被覆ガラス組成物層１００ｗｔ％中０．１〜２０ｗｔ％であることが好ましい。無機顔料の含有量が０．１ｗｔ％未満の場合には，所望の色彩を焼成後の上記無鉛被覆ガラス組成物層に与えることができないおそれがある。一方，２０ｗｔ％を超える場合には，焼成後の無鉛被覆ガラス組成物層の耐久性が低下するおそれがある。
【００２８】
また，上記発熱用金属組成物層及び無鉛被覆ガラス組成物層は，１版又は２版以上のスクリーン印刷にて形成することができる。好ましくは２版以上であり，この場合には，上記発熱用金属組成物層を形成しやすくなると共に，無鉛被覆ガラス組成物層を均一に形成し易くなる。そのため，焼成後の電磁調理用無鉛発熱膜の耐久性が向上し，寿命を向上させることができる。
【００２９】
次に，上記無鉛被覆ガラス組成物層の厚みは２０μｍ以上であることが好ましい（請求項２）。
この場合には，焼成後の上記無鉛被覆ガラス組成物層の厚みが１０μｍ以上となり，耐摩耗性が向上する。
上記無鉛被覆ガラス組成物層の厚みが２０μｍ未満の場合には，焼成後の上記無鉛被覆ガラス組成物層の厚みが１０μｍ未満となるおそれがあり，耐摩耗性が低下して，焼成後の電磁調理用無鉛発熱膜の寿命が短くなるおそれがある。
さらに好ましくは，上記無鉛被覆ガラス組成物層の厚みは３０μｍ以上がよい。この場合には，上記無鉛被覆ガラス組成物層の焼成後の厚みがさらに大きくなり，耐久性がさらに向上する。
【００３０】
次に，上記電磁調理用無鉛発熱膜は８００〜９００℃にて焼成可能であることが好ましい（請求項３）。
この場合には，８００〜９００℃にて上記電磁調理用無鉛発熱膜を焼成することができる。そして，８００〜９００℃にて焼成した場合には，焼成後の上記電磁調理用無鉛発熱膜は，容器の表面に充分な接着強度にて，接着することができる。
焼成温度が８００℃未満の場合には，焼成後の上記電磁調理用無鉛発熱膜が，容器の表面から剥がれやすくなるおそれがある。一方，９００℃を超える場合には，焼成時に上記無鉛ガラスが発泡する等の不具合が発生し易くなるおそれがある。
【００３１】
次に，上記無鉛ガラス及び無鉛被覆ガラス組成物層は，ＳｉＯ_２−Ａｌ_２Ｏ_３−Ｂ_２Ｏ_３−ＲＯ系ガラス（Ｒは，Ｃａ，Ｓｒ，Ｂａ，又はＭｇから選ばれる１種以上）よりなり，上記ＳｉＯ_２−Ａｌ_２Ｏ_３−Ｂ_２Ｏ_３−ＲＯ系ガラス１００ｗｔ％中にＢ_２Ｏ_３を３〜２５ｗｔ％，ＲＯを１０〜５５ｗｔ％含有することであることが好ましい（請求項４）。
【００３２】
この場合には，焼成温度８００℃〜９００℃にて上記電磁調理用無鉛発熱膜の焼成を行うことができると共に，焼成後の上記電磁調理用無鉛発熱膜を容器に充分に密着させることができる。また，焼成後の上記無鉛被覆ガラス組成物層を表面平滑性及び耐久性に優れ，かつ光沢を有するものとすることができる。なお，上記ＳｉＯ_２−Ａｌ_２Ｏ_３−Ｂ_２Ｏ_３−ＲＯ系ガラスは，ＳｉＯ_２，Ａｌ_２Ｏ_３，Ｂ_２Ｏ_３，及びＲＯ（Ｒは，Ｃａ，Ｓｒ，Ｂａ，又はＭｇから選ばれる１種以上）を必須成分として含有するガラスであるが，その他の成分としてアルカリ金属酸化物，ＺｎＯ，Ｂｉ_２Ｏ_３，Ｐ_２Ｏ_５，ＴｉＯ_２等を含有していてもよい。
【００３３】
上記Ｂ_２Ｏ_３の含有量が３ｗｔ％未満の場合には，転移点及び屈伏点が高くなりすぎて焼成が困難になり，焼成後に上記電磁調理用無鉛発熱膜が剥がれ易くなるおそれがある。また，一方，２５ｗｔ％を超える場合には，焼成時に発泡し易くなり，耐久性が劣化するおそれがある。上記Ｂ_２Ｏ_３の含有量は５〜２０ｗｔ％であることがより好ましい。
【００３４】
また，上記ＲＯの含有量が１０ｗｔ％未満の場合には，転移点及び屈伏点が高くなりすぎて焼成が困難になり，焼成後に上記電磁調理用無鉛発熱膜が剥がれ易くなるおそれがある。一方，５５ｗｔ％を超える場合には，転移点及び屈伏点が低下し，耐熱性が劣化して断線などの不具合を生じやすくなるおそれがある。上記ＲＯの含有量は，１５〜４５ｗｔ％であることがより好ましい。
また，上記ＲＯにおいて，Ｒは，Ｃａ，Ｓｒ，Ｂａ，又はＭｇから選ばれる１種以上であり，即ちＲＯは，ＣａＯ，ＳｒＯ，ＢａＯ，ＭｇＯから選ばれる１種以上である。
【００３５】
また，上記第２の発明（請求項５）においては，上記金属と無鉛ガラスとの混合割合は，両者を１００重量部としたとき，金属が８５〜９９重量部で，無鉛ガラスが１〜１５重量部である。
上記金属が８５重量部未満の場合，又は無鉛ガラスが１５重量部を超える場合には，上記無鉛発熱膜を効率よく発熱させることができない。一方，上記金属が９９重量部を超える場合，又は無鉛ガラスが１重量％未満の場合には，上記無鉛発熱膜と容器との密着性が低下し，剥がれを生じ易くなる。
【００３６】
また，上記無鉛ガラス及び無鉛被覆ガラス層は，転移点が５５０℃〜７００℃であり，かつ屈伏点が６５０℃〜７５０℃である。上記転移点が５５０℃未満の場合または屈伏点が６５０℃未満の場合には，無鉛ガラス及び無鉛被覆ガラス層が再溶融し易いため，２００Ｖ対応の高出力電磁調理器に使用することができない。一方，転移点が７００℃を超える場合又は屈伏点が７５０℃を超える場合には，上記発熱用金属層が剥がれ易くなる。
【００３７】
また，上記無鉛発熱膜は，容器の内側又は外側に形成することができる。好ましくは，内側に形成するのがよい。この場合には，容器の内側が発熱し，容器内の食材等を効率的に加熱することができる。
【００３８】
また，上記無鉛被覆ガラス層は，無機顔料を含有することが好ましい。この場合には，上記無鉛被覆ガラス層に色彩を与えることができる。ここで，上記無機顔料の含有量は，無鉛被覆ガラス層１００ｗｔ％中０．１〜２０ｗｔ％であることが好ましい。無機顔料の含有量が０．１ｗｔ％未満の場合には，所望の色彩を上記無鉛被覆ガラス層に与えることができないおそれがある。一方，２０ｗｔ％を超える場合には，上記無鉛被覆ガラス層の耐久性が低下するおそれがある。
【００３９】
また，上記発熱用金属層又は／及び無鉛被覆ガラス層は，１版又は２版以上のスクリーン印刷にて形成されていることが好ましい。さらに好ましくは２版以上であり，この場合には，上記無鉛発熱膜の耐久性が向上し，寿命が向上する。
【００４０】
次に，上記無鉛被覆ガラス層の厚みは１０μｍ以上であることが好ましい（請求項６）。
上記無鉛被覆ガラス層の厚みが１０μｍ未満の場合には，無鉛被覆ガラス層が摩耗し易くなり，上記無鉛発熱膜の寿命が短くなるおそれがある。さらに好ましくは１５μｍ以上がよい。
【００４１】
次に，上記無鉛ガラス及び無鉛被覆ガラス層は，ＳｉＯ_２−Ａｌ_２Ｏ_３−Ｂ_２Ｏ_３−ＲＯ系ガラス（ただし，Ｒは，Ｃａ，Ｓｒ，Ｂａ，又はＭｇから選ばれる１種以上）よりなり，上記ＳｉＯ_２−Ａｌ_２Ｏ_３−Ｂ_２Ｏ_３−ＲＯ系ガラス１００ｗｔ％中にＢ_２Ｏ_３を３〜２５ｗｔ％，ＲＯを１０〜５５ｗｔ％含有することが好ましい（請求項７）。
【００４２】
この場合には，上記発熱用金属層と容器との密着性を向上させることができる。また，上記無鉛被覆ガラス層の表面平滑性及び耐久性が向上し，かつ光沢を有するものとすることができる。なお，上記ＳｉＯ_２−Ａｌ_２Ｏ_３−Ｂ_２Ｏ_３−ＲＯ系ガラスは，ＳｉＯ_２，Ａｌ_２Ｏ_３，Ｂ_２Ｏ_３，及びＲＯ（Ｒは，Ｃａ，Ｓｒ，Ｂａ，又はＭｇ）を必須成分として含有するガラスであるが，その他の成分としてアルカリ金属酸化物，ＺｎＯ，Ｂｉ_２Ｏ_３，Ｐ_２Ｏ_５，ＴｉＯ_２等を含有していてもよい。
【００４３】
上記Ｂ_２Ｏ_３の含有量が３ｗｔ％未満の場合には，転移点及び屈伏点が高くなりすぎて，上記無鉛発熱膜が剥がれ易くなるおそれがある。一方，２５ｗｔ％を超える場合には，焼成時にガラス中に発泡が生じて上記発熱用金属層の耐久性が劣化するおそれがある。上記Ｂ_２Ｏ_３の含有量は１０〜２０ｗｔ％であることがより好ましい。
【００４４】
また，上記ＲＯの含有量が１０ｗｔ％未満の場合には，転移点及び屈伏点が高くなりすぎて，上記無鉛発熱膜が剥がれ易くなるおそれがある。一方，５５ｗｔ％を超える場合には，転移点及び屈伏点が低下し，耐熱性が劣化して断線などの不具合を生じやすくなるおそれがある。上記ＲＯの含有量は，１５〜４５ｗｔ％であることがより好ましい。
また，上記ＲＯにおいて，Ｒは，Ｃａ，Ｓｒ，Ｂａ，又はＭｇから選ばれる１種以上であり，即ちＲＯは，ＣａＯ，ＳｒＯ，ＢａＯ，ＭｇＯから選ばれる１種以上である。
【００４５】
【実施例】
（実施例１）
本例は，上記電磁調理用無鉛発熱膜及び電磁調理用容器を作製する例である。
本例の電磁調理用無鉛発熱膜は，容器に貼着し焼成して電磁調理可能な電磁調理用容器とするための電磁調理用無鉛発熱膜である。
図１に示すごとく，上記電磁調理用無鉛発熱膜１は，裏面側に発熱用金属組成物層１５を有し，その表面側には，無鉛被覆ガラス組成物層１５２を積層してなる。
【００４６】
上記発熱用金属組成物層１５は，銀からなる金属と無鉛ガラスと有機バインダーとの混合物よりなり，上記金属と無鉛ガラスとの混合割合は，両者を１００重量部としたとき，金属が９０重量部で，無鉛ガラスが１０重量部である。
また，上記無鉛ガラス及び無鉛被覆ガラス組成物層１５２は，転移点が６５０℃であり，かつ屈伏点が７００℃である。
【００４７】
また，本例の電磁調理用容器は，図２及び図３に示すごとく，電磁調理容器２の表面に無鉛発熱膜２３を形成してなる電磁調理用容器２である。
上記無鉛発熱膜２３は，電磁調理容器２０側に接合形成した発熱金属層２５と，該発熱金属層２５の表面に設けた無鉛被覆ガラス層２５２とよりなり，上記発熱金属層２５は，金，銀，又は白金よりなる金属９０重量部と，無鉛ガラス１０重量部とからなる。
また，上記無鉛ガラス及び無鉛被覆ガラス層２５２は，転移点が６５０℃であり，かつ屈伏点が７００℃である。
【００４８】
以下，本例の電磁調理用無鉛発熱膜及び電磁調理用容器の製造方法につき図１〜３を用いて説明する。
まず，上記発熱金属組成物層の金属として銀粉末を準備した。また，上記発熱金属組成物層の無鉛ガラスとしては，ＳｉＯ_２を３５ｗｔ％，Ａｌ_２Ｏ_３を１５ｗｔ％，Ｂ_２Ｏ_３を２０ｗｔ％，ＣａＯを１３ｗｔ％，ＢａＯを１０ｗｔ％，ＳｒＯを２ｗｔ％及びＺｎＯを５ｗｔ％含有するＳｉＯ_２−Ａｌ_２Ｏ_３−Ｂ_２Ｏ_３−ＲＯ系ガラスを準備した。
【００４９】
上記ＳｉＯ_２−Ａｌ_２Ｏ_３−Ｂ_２Ｏ_３−ＲＯ系ガラスは，転移点が６５０℃で，屈伏点が７００℃であった。
上記転移点及び屈伏点の測定方法としては，まず上記ＳｉＯ_２−Ａｌ_２Ｏ_３−Ｂ_２Ｏ_３−ＲＯ系ガラスを２５℃から５℃／ｍｉｎの昇温速度にて昇温させ，熱膨張係数を熱機械分析装置を用いて測定した。このとき，溶融石英ガラスを標準試料として用いた。次に，その結果をグラフ上に示し，該グラフから上記転移点及び屈伏点を測定した。なお，上記熱機械分析装置としては，株式会社リガク製の「サーモプラス　ＴＭＡ８３１０」を用いた。
【００５０】
次に，上記銀粉末９０重量部とＳｉＯ_２−Ａｌ_２Ｏ_３−Ｂ_２Ｏ_３−ＲＯ系ガラス１０重量部とを混合し，混合物を得た。この混合物１００重量部に有機バインダーとしてのアクリル系樹脂を３０重量部加えて混合した。そして，図１に示すごとく，この有機バインダーを加えた混合物を２５０メッシュのステンレス版を用いて転写紙１２の上に２版印刷にて，φ１６０ｍｍの円形状となるように印刷し，円形状の発熱用金属組成物層１５を形成した。
【００５１】
次に，上記無鉛被覆ガラス組成物層１５２として，ＳｉＯ_２−Ａｌ_２Ｏ_３−Ｂ_２Ｏ_３−ＲＯ系ガラスを準備した。このＳｉＯ_２−Ａｌ_２Ｏ_３−Ｂ_２Ｏ_３−ＲＯ系ガラスは，本例の上記無鉛ガラスと同じ組成のもので，転移点が６５０℃で，屈伏点が７００℃のものである。
このＳｉＯ_２−Ａｌ_２Ｏ_３−Ｂ_２Ｏ_３−ＲＯ系ガラスを上記円形状の発熱用金属組成物層１５の上に該発熱用金属組成物層１５を覆うように積層印刷し，無鉛被覆ガラス組成物層１５２を形成した。尚，印刷は２版印刷にて行い，無鉛被覆ガラス組成物層１５２の厚みは３２μｍであった。
【００５２】
続いて，上記無鉛被覆ガラス組成物層１５２の上をフィルム１３にて上記無鉛被服ガラス組成物層１５２を覆うようにコートし，円形状の電磁調理用無鉛発熱膜１を作製した。
【００５３】
次に，この円形状の電磁調理用無鉛発熱膜１を発熱用金属組成物層１５側が接するように，容器２０としてのセラミックス製鍋の内側底部（φ１８０ｍｍ）に転写した。
続いて，このセラミックス製の鍋を８３０℃にて１０分間焼成した。この焼成時に，上記電磁調理用無鉛発熱膜１のフィルム１３は消滅した。このようにして，図２及び図３に示す電磁調理用容器２を作製し，これを試料Ｅ１とした。なお，試料Ｅ１における無鉛被覆ガラス層２５２の厚みは，１７μｍであった。
【００５４】
（実施例２）
本例は，実施例１の無鉛ガラスの組成を変えて電磁調理用無鉛発熱膜及び電磁調理用容器を作製した例である。
まず，上記発熱金属組成物層の金属として銀粉末を準備した。また，上記発熱金属組成物層の無鉛ガラスとしては，ＳｉＯ_２を３０ｗｔ％，Ａｌ_２Ｏ_３を１５ｗｔ％，Ｂ_２Ｏ_３を２５ｗｔ％，ＣａＯを８ｗｔ％，ＢａＯを１０ｗｔ％，ＳｒＯを７ｗｔ％及びＺｎＯを５ｗｔ％含有するＳｉＯ_２−Ａｌ_２Ｏ_３−Ｂ_２Ｏ_３−ＲＯ系ガラスを準備した。
【００５５】
上記ＳｉＯ_２−Ａｌ_２Ｏ_３−Ｂ_２Ｏ_３−ＲＯ系ガラスは，転移点が６３０℃で，屈伏点が６８０℃であった。
上記転移点及び屈伏点の測定方法及び測定装置は，実施例１と同様である。
【００５６】
次に，実施例１と同様にして，上記銀粉末９０重量部とＳｉＯ_２−Ａｌ_２Ｏ_３−Ｂ_２Ｏ_３−ＲＯ系ガラス１０重量部とを混合し，混合物を得た。この混合物１００重量部に有機バインダーとしてのアクリル系樹脂を３０重量部加えて混合した。さらに，実施例１と同様にして，上記有機バインダーを加えた混合物を転写紙の上に２版印刷にて印刷し，発熱用金属組成物層を形成した。
【００５７】
次に，上記無鉛被覆ガラス組成物層として，ＳｉＯ_２−Ａｌ_２Ｏ_３−Ｂ_２Ｏ_３−ＲＯ系ガラスを準備した。このＳｉＯ_２−Ａｌ_２Ｏ_３−Ｂ_２Ｏ_３−ＲＯ系ガラスは，本例の無鉛ガラスと同じ組成のもので，転移点が６３０℃で，屈伏点が６８０℃のものである。
このＳｉＯ_２−Ａｌ_２Ｏ_３−Ｂ_２Ｏ_３−ＲＯ系ガラスを実施例１と同様にして，上記発熱用金属組成物層の上に積層印刷し，無鉛被覆ガラス組成物層を形成した。尚，印刷は２版印刷にて行い，無鉛被覆ガラス組成物層の厚みは３０μｍであった。
【００５８】
続いて，実施例１と同様にして，上記無鉛被覆ガラス組成物層の上にフィルムをコートし，電磁調理用無鉛発熱膜を作製した。
【００５９】
次に，実施例１と同様にして，上記電磁調理用無鉛発熱膜をセラミックス製の鍋の内側底部に転写した。
続いて，このセラミックス製の鍋を８３０℃にて１０分間焼成した。この焼成時に，上記電磁調理用無鉛発熱膜のフィルムは消滅した。このようにして，電磁調理用容器を作製し，これを試料Ｅ２とした。なお，試料Ｅ２における無鉛被覆ガラス層の厚みは，１７μｍであった。
【００６０】
（比較例１）
本例は，実施例１及び実施例２の無鉛ガラスの組成を変えて電磁調理用無鉛発熱膜及び電磁調理用容器を作製した例である。
まず，上記発熱金属組成物層の金属として銀粉末を準備した。また，上記発熱金属組成物層の無鉛ガラスとしては，ＳｉＯ_２を１３ｗｔ％，Ａｌ_２Ｏ_３を５ｗｔ％，Ｂ_２Ｏ_３を２７ｗｔ％，ＣａＯを５ｗｔ％，ＢａＯを４０ｗｔ％，及びＳｒＯを１０ｗｔ％含有するＳｉＯ_２−Ａｌ_２Ｏ_３−Ｂ_２Ｏ_３−ＲＯ系ガラスを準備した。
【００６１】
上記ＳｉＯ_２−Ａｌ_２Ｏ_３−Ｂ_２Ｏ_３−ＲＯ系ガラスは，転移点が５８０℃で，屈伏点が６４０℃であった。
上記転移点及び屈伏点の測定方法及び測定装置は，実施例１と同様である。
【００６２】
次に，実施例１及び２と同様にして，上記銀粉末９０重量部とＳｉＯ_２−Ａｌ_２Ｏ_３−Ｂ_２Ｏ_３−ＲＯ系ガラス１０重量部とを混合し，混合物を得た。この混合物１００重量部に有機バインダーとしてのアクリル系樹脂を３０重量部加え混合した。さらに，実施例１と同様にして，転写紙の上に２版印刷にて発熱用金属組成物層を形成した。
【００６３】
次に，上記無鉛被覆ガラス組成物層として，ＳｉＯ_２−Ａｌ_２Ｏ_３−Ｂ_２Ｏ_３−ＲＯ系ガラスを準備した。このＳｉＯ_２−Ａｌ_２Ｏ_３−Ｂ_２Ｏ_３−ＲＯ系ガラスは，本例の無鉛ガラスと同じ組成のもので，転移点が５８０℃で，屈伏点が６４０℃のものである。
このＳｉＯ_２−Ａｌ_２Ｏ_３−Ｂ_２Ｏ_３−ＲＯ系ガラスを実施例１及び２と同様にして，上記発熱用金属組成物層の上に積層印刷し，無鉛被覆ガラス組成物層を形成した。尚，印刷は２版印刷にて行い，無鉛被覆ガラス組成物層の厚みは２８μｍであった。
【００６４】
続いて，実施例１及び２と同様にして，上記無鉛被覆ガラス組成物層の上にフィルムをコートし，電磁調理用無鉛発熱膜を作製した。
【００６５】
次に，実施例１及び２と同様にして，上記電磁調理用無鉛発熱膜をセラミックス製の鍋の内側底部に転写した。
続いて，このセラミックス製の鍋を８３０℃にて１０分間焼成した。この焼成時に，上記電磁調理用無鉛発熱膜のフィルムは消滅した。このようにして，電磁調理用容器を作製し，これを試料Ｃ１とした。なお，試料Ｃ１における無鉛被覆ガラス層の厚みは，１５μｍであった。
【００６６】
（比較例２）
本例は，実施例１，実施例２及び実施例３の無鉛ガラスの組成を変えて電磁調理用無鉛発熱膜及び電磁調理用容器を作製した例である。
まず，上記発熱金属組成物層の金属として銀粉末を準備した。また，上記発熱金属組成物層の無鉛ガラスとしては，ＳｉＯ_２を５５ｗｔ％，Ａｌ_２Ｏ_３を２０ｗｔ％，Ｂ_２Ｏ_３を１５ｗｔ％，ＣａＯを５ｗｔ％，及びＺｎＯを５ｗｔ％含有するＳｉＯ_２−Ａｌ_２Ｏ_３−Ｂ_２Ｏ_３−ＲＯ系ガラスを準備した。
【００６７】
上記ＳｉＯ_２−Ａｌ_２Ｏ_３−Ｂ_２Ｏ_３−ＲＯ系ガラスは，転移点が７１０℃で，屈伏点が７８０℃であった。
上記転移点及び屈伏点の測定方法及び測定装置は，実施例１と同様である。
【００６８】
次に，実施例１及び２と同様にして，上記銀粉末９０重量部とＳｉＯ_２−Ａｌ_２Ｏ_３−Ｂ_２Ｏ_３−ＲＯ系ガラス１０重量部とを混合し，混合物を得た。この混合物１００重量部に有機バインダーとしてのアクリル系樹脂を３０重量部加えた。さらに，実施例１と同様にして，転写紙の上に２版印刷にて発熱用金属組成物層を形成した。
【００６９】
次に，上記無鉛被覆ガラス組成物層として，ＳｉＯ_２−Ａｌ_２Ｏ_３−Ｂ_２Ｏ_３−ＲＯ系ガラスを準備した。このＳｉＯ_２−Ａｌ_２Ｏ_３−Ｂ_２Ｏ_３−ＲＯ系ガラスは，本例の無鉛ガラスと同じ組成のもので，転移点が７１０℃で，屈伏点が７８０℃のものである。
このＳｉＯ_２−Ａｌ_２Ｏ_３−Ｂ_２Ｏ_３−ＲＯ系ガラスを実施例１及び２と同様にして，上記発熱用金属組成物層の上に積層印刷し，無鉛被覆ガラス組成物層を形成した。尚，印刷は２版印刷にて行い，無鉛被覆ガラス組成物層の厚みは２５μｍであった。
【００７０】
続いて，実施例１及び２と同様にして，上記無鉛被覆ガラス組成物層の上にフィルムをコートし，電磁調理用無鉛発熱膜を作製した。
【００７１】
次に，実施例１及び２と同様にして，上記電磁調理用無鉛発熱膜をセラミックス製の鍋の内側底部に転写した。
続いて，このセラミックス製の鍋を８３０℃にて１０分間焼成した。この焼成時に，上記電磁調理用無鉛発熱膜のフィルムは消滅した。このようにして，電磁調理用容器を作製し，これを試料Ｃ２とした。なお，試料Ｃ２における無鉛被覆ガラス層の厚みは，１３μｍであった。
【００７２】
（従来例）
本例では，有鉛ガラスを用いて電磁調理用発熱膜及び電磁調理用容器を作製した例を示す。
まず，上記発熱金属組成物層の金属として銀粉末を準備した。また，上記実施例１及び２の発熱金属組成物層の無鉛ガラスに変えて，ＰｂＯを５０ｗｔ％，ＳｉＯ_２を２５ｗｔ％，Ａｌ_２Ｏ_３を５ｗｔ％，Ｂ_２Ｏ_３を２０ｗｔ％含有する有鉛ガラスを準備した。
【００７３】
上記有鉛ガラスは，転移点が４５０℃で，屈伏点が５７０℃であった。
上記転移点及び屈伏点の測定方法及び測定装置は，実施例１と同様である。
【００７４】
次に，実施例１及び２と同様にして，上記銀粉末９０重量部と上記有鉛ガラス１０重量部とを混合し，混合物を得た。この混合物１００重量部に有機バインダーとしてのアクリル系樹脂を３０重量部加えて混合した。この有機バインダーを加えた混合物を２５０メッシュのステンレス版を用いて，転写紙の上に１版印刷にて印刷し，発熱用金属組成物層を形成した。
【００７５】
次に，ＳｉＯ_２を６０ｗｔ％，Ａｌ_２Ｏ_３を５ｗｔ％，Ｂ_２Ｏ_３を２０ｗｔ％，Ｎａ_２Ｏを１０ｗｔ％，及びＺｎＯを５ｗｔ％含有するガラスを準備した。
このガラスを実施例１及び２と同様にして，上記発熱用金属組成物層の上に積層印刷し，被覆ガラス層を形成した。尚，印刷は２版印刷にて行い，被覆ガラス層の厚みは２０μｍであった。
【００７６】
続いて，実施例１及び２と同様にして，上記被覆ガラス層の上にフィルムをコートし，電磁調理用発熱膜を作製した。
【００７７】
次に，実施例１及び２と同様にして，上記電磁調理用発熱膜をセラミックス製の鍋の内側底部に転写した。
続いて，このセラミックス製の鍋を８３０℃にて１０分間焼成した。この焼成時に，上記電磁調理用発熱膜のフィルムは消滅した。このようにして，電磁調理用容器を作製し，これを試料Ｃ３とした。なお，試料Ｃ３における被覆ガラス層の厚みは９μｍであった。
【００７８】
（実験例）
上記試料Ｅ１，試料Ｅ２，及び試料Ｃ１〜試料Ｃ３について，焼成後の光沢を目視にて観察した。観察は従来品である試料Ｃ３と比較することにより行った。
また，焼成後の無鉛被覆ガラス層及び被覆ガラス層の厚さを電子顕微鏡を用いて測定した。
その結果を表１に示す。
【００７９】
次に，上記試料Ｅ１，試料Ｅ２，及び試料Ｃ１〜試料Ｃ３の５種類の電磁調理用容器に水１５００ｃｃを注ぎ，２００Ｖ対応の高出力電磁調理器（株式会社日立製作所製　ＨＴ−３２ＣＢ形）に設置し，出力１８００Ｗにて水１５００ｃｃを完全に沸騰させるまでの時間を測定した。次に，１５分間空焚きをおこない，空焚き後，各試料における無鉛被覆ガラス層及び被覆ガラス層の変化を目視にて観察した。なお，本実験例にて使用した上記の５種類の電磁調理用容器は，容量２０００ｃｃの同一形状のものである。
その結果を表１に示す。
【００８０】
【表１】

【００８１】
表１より知られるごとく，本発明品である試料Ｅ１及び試料Ｅ２の表面の光沢性は，従来品（試料Ｃ３）よりも優れていた。これに対し，試料Ｃ１は被覆ガラスの一部が発泡していた。また，試料Ｃ２は艶消し状で光沢性を欠いており，表面の一部が剥離していた。また，試料Ｅ１及び試料Ｅ２の無鉛被覆ガラス層は，１０μｍ以上という充分な厚みを有している。そのため，耐久性に優れている。これに対し，試料Ｃ３は，厚みが９μｍしかないため，無鉛被覆ガラス層が摩耗し易く，発熱膜の寿命が短くなるおそれがある。
【００８２】
また，上記試料Ｅ１及び試料Ｅ２は，５分以内という短い時間で１５００ｃｃの水を沸騰させ，さらに１５分間の空焚き後も無鉛被覆ガラスの表面には溶融等の変化もなく，熱伝導性に優れていると共に，耐熱性にも優れるものであった。これに対し，試料Ｃ１〜Ｃ３は，空焚き後，被覆ガラス層の一部に剥離または溶融している部分があり，耐熱性が低かった。また，試料Ｃ３は，人体に有害な鉛を含有しているため，安全性に問題があった。
【図面の簡単な説明】
【図１】実施例１にかかる，電磁調理用無鉛発熱膜を示す説明図。
【図２】実施例１にかかる，電磁調理用容器を示す説明図。
【図３】図２の電磁調理用容器のＡ−Ａ線矢視断面図。
【符号の説明】
１．．．電磁調理用無鉛発熱膜，
１５．．．発熱用金属組成物層，
１５２．．．無鉛被覆ガラス組成物層，
２．．．電磁調理用容器，
２３．．．無鉛発熱膜，
２５．．．発熱金属層，
２５２．．．無鉛被覆ガラス層，[0001]
【Technical field】
The present invention relates to a lead-free heating film for electromagnetic cooking and a container for electromagnetic cooking, which are compatible with a high-output electromagnetic cooking device.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, an electromagnetic cooker has been widely used as a substitute for a gas stove due to its high safety. The electromagnetic cooker uses electromagnetic induction to generate heat by a skin effect in an electromagnetic cooking container installed on the electromagnetic cooker and heat it. Also, in recent years, 200 V-compatible electromagnetic cookers having even higher output have rapidly spread.
[0003]
The above-mentioned electromagnetic cooking container which can be used for the electromagnetic cooker has an effective resistance of 4 to 20 × 10 using a skin effect of a magnetic metal or electromagnetic induction in principle. ^-4 It was a conductor that became Ω. Therefore, there is a problem that a cooking device such as a pan made of aluminum, copper, or ceramics cannot be heated by an electromagnetic cooking device.
[0004]
In order to generate heat from a ceramic cooker using an electromagnetic cooker, a method has been developed in which a heating element film made of gold, silver, and platinum is provided on the bottom of a cooker made of a low-thermal-expansion base (Jun. -11436). The heating element film includes a metal layer joined by a bonding glass layer, and a glass coat layer for protecting the metal layer. The cooking device whose surface is covered with the heating film can be used in an electromagnetic cooking device because the heating film generates heat by a skin effect.
[0005]
[Problem to be solved]
However, the heating element film has a transition point of less than 500 ° C. and a sag point of 650 in the metal layer or the glass coating layer so as to maintain sufficient adhesion strength when fired at a temperature of 900 ° C. or less. It contains leaded glass with a low melting point of less than ° C. Therefore, when the cooking device covered with the heating element film is heated by, for example, a high-output electromagnetic cooking device corresponding to 200 V, the surface temperature of the heating element film may increase to around 500 ° C. There has been a problem that the glass component is softened or re-melted, causing problems such as disconnection during use.
[0006]
In addition, when the heating film is coated on the inside of the cooking device, foods and the like inside the cooking device can be efficiently heated. However, since the heating element film contains lead harmful to the human body in its glass component, there is a problem that it is difficult to coat the inside of the cooking device.
[0007]
SUMMARY OF THE INVENTION The present invention has been made in view of such conventional problems, and provides a lead-free heat generating film for electromagnetic cooking and a container for electromagnetic cooking which do not contain lead and can be used in a high-output electromagnetic cooker. It is assumed that.
[0008]
[Means for solving the problem]
A first invention is a lead-free heat generating film for electromagnetic cooking, which is attached to a container and fired to form an electromagnetic cooking container capable of electromagnetic cooking,
The above-mentioned lead-free heat generating film for electromagnetic cooking has a metal composition layer for heat generation on the back surface side and a lead-free coated glass composition layer laminated on the front side,
The heat-generating metal composition layer is made of a mixture of a metal made of gold, silver, or platinum, a lead-free glass, and an organic binder,
The mixing ratio of the metal and the lead-free glass is 85 to 99 parts by weight of the metal and 1 to 15 parts by weight of the lead-free glass when both are 100 parts by weight.
The lead-free glass and the lead-free coated glass composition layer have a transition point of 550 ° C. to 700 ° C. and a sag point of 650 ° C. to 750 ° C., which is a lead-free heat-generating film for electromagnetic cooking. 1).
[0009]
In the present invention, the lead-free heat-generating film for electromagnetic cooking has a heat-generating metal composition layer made of a mixture of a metal made of gold, silver, or platinum, a lead-free glass, and an organic binder. Therefore, when the lead-free heat-generating film for electromagnetic cooking is attached to a container and fired, the container becomes an electromagnetic cooking container capable of performing electromagnetic cooking.
[0010]
The lead-free glass and the lead-free coated glass composition layer have a transition point of 550 ° C. to 700 ° C. and a sag point of 650 ° C. to 750 ° C.
Therefore, the electromagnetic cooking container in which the above-described lead-free heat generating film for electromagnetic cooking is adhered and baked can be used, for example, in a high-output electromagnetic cooker corresponding to 200 V. As described above, the fired lead-free glass and lead-free coated glass composition layer having a high transition point of 550 ° C to 700 ° C and a high yield point of 650 ° C to 750 ° C are used in a high-output electromagnetic cooker. However, it does not melt again.
[0011]
The lead-free heat-generating film for electromagnetic cooking has a heat-generating metal composition layer on the back side adhered to the container, and a lead-free coated glass composition layer laminated on the front side.
Therefore, when the lead-free heat-generating film for electromagnetic cooking is attached to a container and fired, the surface of the heat-generating metal composition layer after firing is covered with the lead-free coated glass composition layer after firing. Therefore, the heat-generating metal composition layer after firing does not come into direct contact with other substances, and the fired metal composition layer after firing does not deteriorate due to friction or the like.
[0012]
The mixing ratio of the metal and the lead-free glass is 85 to 99 parts by weight and the lead-free glass is 1 to 15 parts by weight, when both are 100 parts by weight.
Therefore, the lead-free heat-generating film for electromagnetic cooking can melt the lead-free glass at the time of firing and adhere sufficiently to the container. After firing, the metal baked on the surface of the container can be heated by induction heating of an electromagnetic cooker or the like. It can generate enough heat.
[0013]
The lead-free heating film for electromagnetic cooking contains a lead-free glass and a lead-free coated glass composition layer, and does not contain lead harmful to the human body in the composition. Therefore, the lead-free heating film for electromagnetic cooking can be adhered to the inside of the container.
[0014]
As described above, according to the present invention, it is possible to provide a lead-free heat generating film for electromagnetic cooking that does not contain lead and can be used in a high-output electromagnetic cooker.
[0015]
A second invention is an electromagnetic cooking container having a lead-free heating film formed on the surface of the container,
The lead-free heat-generating film is composed of a heat-generating metal layer bonded to the container side and a lead-free coated glass layer provided on the surface of the heat-generating metal layer.
The heating metal layer is composed of 85 to 99 parts by weight of a metal made of gold, silver, or platinum and 1 to 15 parts by weight of lead-free glass.
The lead-free glass and the lead-free coated glass layer have a transition point of 550 ° C. to 700 ° C. and a sag point of 650 ° C. to 750 ° C. in an electromagnetic cooking container (Claim 5).
[0016]
In the present invention, since the electromagnetic cooking container has a heat-generating metal layer on the surface of the container, the heat-generating metal layer generates heat due to a skin effect caused by electromagnetic induction, so that electromagnetic cooking is possible.
The heat-generating metal layer is composed of 85 to 99 parts by weight of a metal made of gold, silver or platinum, and 1 to 15 parts by weight of lead-free glass. Therefore, the heat-generating metal layer forms a continuous layer, can generate heat sufficiently by electromagnetic cooking, and is in close contact with the container.
[0017]
A lead-free coated glass layer is provided on the surface of the heat-generating metal layer, and both layers form a continuous layer. Therefore, the heat-generating metal layer is protected by the lead-free coated glass layer and has excellent durability. Further, the lead-free coated glass layer covers the heat-generating metal layer, and adheres the heat-generating metal layer to the surface of the container with good adhesion.
[0018]
The lead-free glass and the lead-free coated glass layer have a high transition point of 550 ° C. to 700 ° C. and a high yield point of 650 ° C. to 750 ° C.
Therefore, in the electromagnetic cooking container, the lead-free glass and the lead-free coated glass layer hardly re-melt during use, and can be used, for example, in a high-output electromagnetic cooker corresponding to 200 V.
[0019]
The lead-free heat-generating film contains a lead-free glass and a lead-free coated glass layer, and does not contain lead harmful to the human body in the composition. Therefore, it is excellent in safety.
[0020]
As described above, according to the present invention, it is possible to provide an electromagnetic cooking container that does not contain lead and can be used in a high-output electromagnetic cooker.
[0021]
BEST MODE FOR CARRYING OUT THE INVENTION
In the first invention (claim 1), the mixing ratio of the metal and the lead-free glass is 85 to 99 parts by weight and the lead-free glass is 1 to 15 parts by weight when both are 100 parts by weight. It is.
When the amount of the metal is less than 85 parts by weight or the amount of the lead-free glass exceeds 15 parts by weight, the lead-free heat-generating film for electromagnetic cooking after firing cannot be sufficiently heated. On the other hand, when the amount of the metal exceeds 99 parts by weight or the amount of the lead-free glass is less than 1% by weight, it becomes difficult for the lead-free heat generating film for electromagnetic cooking to sufficiently adhere to the container, and it is easy to peel off after firing. .
[0022]
More preferable ranges of the mixing ratio are 90 to 95 parts by weight of metal and 5 to 10 parts by weight of lead-free glass, when both are 100 parts by weight.
In this case, the heat generation of the lead-free heating film for electromagnetic cooking after firing can be further improved.
[0023]
In addition, the above-mentioned lead-free glass and lead-free coated glass composition layer have a transition point of 550 ° C or higher.
700 ° C, and the yield point is 650 ° C to 750 ° C. When the above transition point is less than 550 ° C. or the yield point is less than 650 ° C., the lead-free glass and the lead-free coated glass composition layer after firing are easily re-melted. Can not be used. On the other hand, when the transition point exceeds 700 ° C. or the sag point exceeds 750 ° C., the transition point and the sagging point are too high to make firing difficult, and the lead-free heat-generating film for electromagnetic cooking after firing. Is easily peeled off.
[0024]
Further, the lead-free heating film for electromagnetic cooking can be attached to the inside or outside of the container. Preferably, it is good to stick on the inside. In this case, a container for electromagnetic cooking in which the inside of the container generates heat can be manufactured, and foods and the like in the container can be efficiently heated.
[0025]
The organic binder may be contained in an amount of 20 to 100 parts by weight based on 100 parts by weight of the mixture of the metal and the lead-free glass. When the content of the organic binder is less than 20 parts by weight, it may be difficult to form the heat-generating metal composition layer into a uniform shape and thickness, for example, by screen printing. . On the other hand, if it exceeds 100 parts by weight, the organic binder may remain after baking, and the lead-free heat-generating film for electromagnetic cooking after baking may be easily broken.
[0026]
As the organic binder, for example, an acrylic resin, an alkyd resin, a butyl resin, an ethylcellulose resin, a nitrocellulose resin, a methylcellulose resin, or the like can be used.
[0027]
The lead-free coated glass composition layer may contain an inorganic pigment. In this case, a color can be given to the lead-free coated glass composition layer after firing. Here, the content of the inorganic pigment is preferably 0.1 to 20% by weight in 100% by weight of the lead-free coated glass composition layer. When the content of the inorganic pigment is less than 0.1% by weight, a desired color may not be given to the lead-free coated glass composition layer after firing. On the other hand, if it exceeds 20 wt%, the durability of the lead-free coated glass composition layer after firing may be reduced.
[0028]
The heat-generating metal composition layer and the lead-free coated glass composition layer can be formed by screen printing of one plate or two or more plates. Preferably, the number of plates is two or more. In this case, the heat-generating metal composition layer is easily formed, and the lead-free coated glass composition layer is easily formed uniformly. Therefore, the durability of the lead-free heating film for electromagnetic cooking after firing is improved, and the life can be improved.
[0029]
Next, the thickness of the lead-free coated glass composition layer is preferably 20 μm or more (claim 2).
In this case, the thickness of the lead-free coated glass composition layer after firing becomes 10 μm or more, and the wear resistance is improved.
If the thickness of the lead-free coated glass composition layer is less than 20 μm, the thickness of the lead-free coated glass composition layer after firing may be less than 10 μm, the abrasion resistance is reduced, and the electromagnetic properties after firing are reduced. The life of the lead-free heating film for cooking may be shortened.
More preferably, the thickness of the lead-free coated glass composition layer is 30 μm or more. In this case, the thickness of the lead-free coated glass composition layer after firing is further increased, and the durability is further improved.
[0030]
Next, it is preferable that the lead-free heat generating film for electromagnetic cooking can be fired at 800 to 900 ° C. (claim 3).
In this case, the lead-free heating film for electromagnetic cooking can be fired at 800 to 900 ° C. And when baked at 800-900 degreeC, the said lead-free heating film for electromagnetic cooking after baking can adhere | attach with sufficient adhesive strength on the surface of a container.
If the firing temperature is lower than 800 ° C., the lead-free heat-generating film for electromagnetic cooking after firing may be easily peeled off from the surface of the container. On the other hand, when the temperature exceeds 900 ° C., there is a possibility that problems such as foaming of the lead-free glass during firing may easily occur.
[0031]
Next, the lead-free glass and the lead-free coated glass composition layer are made of SiO 2 ₂ -Al ₂ O ₃ -B ₂ O ₃ -Made of RO glass (R is at least one selected from Ca, Sr, Ba, and Mg); ₂ -Al ₂ O ₃ -B ₂ O ₃ -B in 100 wt% of RO glass ₂ O ₃ Is preferably contained in an amount of 3 to 25 wt% and RO in an amount of 10 to 55 wt% (claim 4).
[0032]
In this case, the lead-free heating film for electromagnetic cooking can be fired at a firing temperature of 800 ° C. to 900 ° C., and the lead-free heating film for electromagnetic cooking after firing can be sufficiently adhered to the container. . Further, the lead-free coated glass composition layer after firing can be made excellent in surface smoothness and durability and glossy. The above SiO ₂ -Al ₂ O ₃ -B ₂ O ₃ -RO glass is made of SiO ₂ , Al ₂ O ₃ , B ₂ O ₃ , And RO (R is one or more selected from Ca, Sr, Ba, and Mg) as essential components, and alkali metal oxide, ZnO, Bi as other components. ₂ O ₃ , P ₂ O ₅ , TiO ₂ Etc. may be contained.
[0033]
B above ₂ O ₃ If the content of is less than 3 wt%, the transition point and the yield point become too high to make firing difficult, and the lead-free heating film for electromagnetic cooking may be easily peeled off after firing. On the other hand, if it exceeds 25 wt%, foaming is likely to occur during firing, and durability may be degraded. B above ₂ O ₃ Is more preferably 5 to 20 wt%.
[0034]
If the RO content is less than 10 wt%, the transition point and the sagging point are too high to make firing difficult, and the lead-free heating film for electromagnetic cooking may be easily peeled off after firing. On the other hand, if it exceeds 55 wt%, the transition point and the yield point may be reduced, heat resistance may be degraded, and problems such as disconnection may easily occur. The RO content is more preferably 15 to 45 wt%.
In the RO, R is at least one selected from Ca, Sr, Ba, and Mg, that is, RO is at least one selected from CaO, SrO, BaO, and MgO.
[0035]
In the second invention (claim 5), the mixing ratio of the metal and the lead-free glass is 85 to 99 parts by weight of the metal and 1 to 15 parts by weight of the lead-free glass when both are 100 parts by weight. Parts by weight.
When the amount of the metal is less than 85 parts by weight or the amount of the lead-free glass exceeds 15 parts by weight, the lead-free heat generating film cannot be efficiently heated. On the other hand, when the amount of the metal exceeds 99 parts by weight or the amount of the lead-free glass is less than 1% by weight, the adhesion between the lead-free heat generating film and the container is reduced, and peeling is likely to occur.
[0036]
The lead-free glass and the lead-free coated glass layer have a transition point of 550 ° C. to 700 ° C. and a sag point of 650 ° C. to 750 ° C. When the transition point is less than 550 ° C. or the yield point is less than 650 ° C., the lead-free glass and the lead-free coated glass layer are likely to be re-melted, and cannot be used in a 200 V-compatible high-power electromagnetic cooker. On the other hand, when the transition point exceeds 700 ° C. or the sag point exceeds 750 ° C., the heat-generating metal layer is easily peeled off.
[0037]
Further, the lead-free heating film can be formed inside or outside the container. Preferably, it is formed inside. In this case, the inside of the container generates heat, and the foods and the like in the container can be efficiently heated.
[0038]
The lead-free coated glass layer preferably contains an inorganic pigment. In this case, the lead-free coated glass layer can be given a color. Here, the content of the inorganic pigment is preferably 0.1 to 20% by weight in 100% by weight of the lead-free coated glass layer. If the content of the inorganic pigment is less than 0.1 wt%, a desired color may not be given to the lead-free coated glass layer. On the other hand, if it exceeds 20 wt%, the durability of the lead-free coated glass layer may be reduced.
[0039]
Further, it is preferable that the heat-generating metal layer and / or the lead-free coated glass layer is formed by screen printing of one plate or two or more plates. More preferably, the number of plates is two or more. In this case, the durability of the lead-free heating film is improved, and the life is improved.
[0040]
Next, the thickness of the lead-free coated glass layer is preferably at least 10 μm.
If the thickness of the lead-free coated glass layer is less than 10 μm, the lead-free coated glass layer is likely to be worn, and the life of the lead-free heating film may be shortened. More preferably, it is 15 μm or more.
[0041]
Next, the lead-free glass and the lead-free coated glass layer are made of SiO 2 ₂ -Al ₂ O ₃ -B ₂ O ₃ -RO glass (where R is at least one selected from Ca, Sr, Ba, and Mg); ₂ -Al ₂ O ₃ -B ₂ O ₃ -B in 100 wt% of RO glass ₂ O ₃ Is preferably contained at 3 to 25 wt% and RO at 10 to 55 wt%.
[0042]
In this case, the adhesion between the heat generating metal layer and the container can be improved. In addition, the surface smoothness and durability of the lead-free coated glass layer can be improved, and the glass layer can have gloss. The above SiO ₂ -Al ₂ O ₃ -B ₂ O ₃ -RO glass is made of SiO ₂ , Al ₂ O ₃ , B ₂ O ₃ , And RO (R is Ca, Sr, Ba, or Mg) as an essential component, but alkali metal oxide, ZnO, Bi ₂ O ₃ , P ₂ O ₅ , TiO ₂ Etc. may be contained.
[0043]
B above ₂ O ₃ If the content is less than 3 wt%, the transition point and the yield point become too high, and the lead-free heat-generating film may be easily peeled off. On the other hand, if it exceeds 25 wt%, foaming may occur in the glass during firing, and the durability of the heat-generating metal layer may be deteriorated. B above ₂ O ₃ Is more preferably 10 to 20% by weight.
[0044]
If the RO content is less than 10% by weight, the transition point and the yield point become too high, and the lead-free heat-generating film may be easily peeled off. On the other hand, if it exceeds 55 wt%, the transition point and the yield point may be reduced, heat resistance may be degraded, and problems such as disconnection may easily occur. The RO content is more preferably 15 to 45 wt%.
In the RO, R is at least one selected from Ca, Sr, Ba, and Mg, that is, RO is at least one selected from CaO, SrO, BaO, and MgO.
[0045]
【Example】
(Example 1)
This example is an example in which the above-described lead-free heating film for electromagnetic cooking and the container for electromagnetic cooking are manufactured.
The lead-free heat-generating film for electromagnetic cooking according to the present embodiment is a lead-free heat-generating film for electromagnetic cooking which is adhered to a container and fired to form an electromagnetic cooking container capable of electromagnetic cooking.
As shown in FIG. 1, the lead-free heat-generating film for electromagnetic cooking 1 has a heat-generating metal composition layer 15 on the back side and a lead-free coated glass composition layer 152 on the front side.
[0046]
The heat-generating metal composition layer 15 is composed of a mixture of a silver metal, a lead-free glass, and an organic binder. The mixing ratio of the metal and the lead-free glass is 90 parts by weight when both are 100 parts by weight. Parts by weight of the lead-free glass is 10 parts by weight.
The lead-free glass and the lead-free coated glass composition layer 152 have a transition point of 650 ° C. and a sag point of 700 ° C.
[0047]
The electromagnetic cooking container of the present embodiment is, as shown in FIGS. 2 and 3, an electromagnetic cooking container 2 in which a lead-free heating film 23 is formed on the surface of the electromagnetic cooking container 2.
The lead-free heat-generating film 23 includes a heat-generating metal layer 25 bonded to the electromagnetic cooking container 20 side and a lead-free coated glass layer 252 provided on the surface of the heat-generating metal layer 25. It consists of 90 parts by weight of a metal made of silver or platinum and 10 parts by weight of lead-free glass.
The lead-free glass and the lead-free coated glass layer 252 have a transition point of 650 ° C. and a sag point of 700 ° C.
[0048]
Hereinafter, a method of manufacturing the lead-free heating film for electromagnetic cooking and the container for electromagnetic cooking of the present embodiment will be described with reference to FIGS.
First, silver powder was prepared as a metal of the heat generating metal composition layer. The lead-free glass of the heat-generating metal composition layer may be SiO 2. ₂ 35 wt%, Al ₂ O ₃ 15 wt%, B ₂ O ₃ Containing 20 wt%, 13 wt% of CaO, 10 wt% of BaO, 2 wt% of SrO and 5 wt% of ZnO ₂ -Al ₂ O ₃ -B ₂ O ₃ -An RO glass was prepared.
[0049]
The above SiO ₂ -Al ₂ O ₃ -B ₂ O ₃ The -RO glass had a transition point of 650 ° C and a yield point of 700 ° C.
As a method of measuring the transition point and the yield point, first, the SiO 2 ₂ -Al ₂ O ₃ -B ₂ O ₃ The temperature of the RO glass was raised from 25 ° C. at a rate of 5 ° C./min, and the coefficient of thermal expansion was measured using a thermomechanical analyzer. At this time, fused quartz glass was used as a standard sample. Next, the results are shown on a graph, from which the above transition point and yield point were measured. In addition, "Thermoplus TMA8310" manufactured by Rigaku Corporation was used as the thermomechanical analyzer.
[0050]
Next, 90 parts by weight of the silver powder and SiO ₂ -Al ₂ O ₃ -B ₂ O ₃ -RO glass was mixed with 10 parts by weight to obtain a mixture. To 100 parts by weight of this mixture, 30 parts by weight of an acrylic resin as an organic binder was added and mixed. Then, as shown in FIG. 1, the mixture to which the organic binder was added was printed on the transfer paper 12 using a 250-mesh stainless steel plate by two-plate printing so as to have a circular shape of φ160 mm. The heat-generating metal composition layer 15 was formed.
[0051]
Next, as the lead-free coated glass composition layer 152, SiO 2 ₂ -Al ₂ O ₃ -B ₂ O ₃ -An RO glass was prepared. This SiO ₂ -Al ₂ O ₃ -B ₂ O ₃ The -RO glass has the same composition as the lead-free glass of the present example, and has a transition point of 650 ° C and a yield point of 700 ° C.
This SiO ₂ -Al ₂ O ₃ -B ₂ O ₃ -RO-based glass was laminated and printed on the circular heat-generating metal composition layer 15 so as to cover the heat-generating metal composition layer 15, thereby forming a lead-free coated glass composition layer 152. The printing was performed by two-plate printing, and the thickness of the lead-free coated glass composition layer 152 was 32 μm.
[0052]
Subsequently, the lead-free coated glass composition layer 152 was coated with a film 13 so as to cover the lead-free coated glass composition layer 152, thereby producing a circular lead-free heating film 1 for electromagnetic cooking.
[0053]
Next, this circular lead-free heat-generating film for electromagnetic cooking 1 was transferred to the inner bottom (φ180 mm) of a ceramic pot as the container 20 so that the heat-generating metal composition layer 15 was in contact therewith.
Subsequently, the ceramic pot was fired at 830 ° C. for 10 minutes. During the firing, the film 13 of the lead-free heating film for electromagnetic cooking 1 disappeared. In this way, the electromagnetic cooking container 2 shown in FIGS. 2 and 3 was produced, and this was used as a sample E1. Note that the thickness of the lead-free coated glass layer 252 in the sample E1 was 17 μm.
[0054]
(Example 2)
In this example, the composition of the lead-free glass of Example 1 was changed to produce a lead-free heat generating film for electromagnetic cooking and a container for electromagnetic cooking.
First, silver powder was prepared as a metal of the heat generating metal composition layer. The lead-free glass of the heat-generating metal composition layer may be SiO 2. ₂ 30 wt%, Al ₂ O ₃ 15 wt%, B ₂ O ₃ Containing 25 wt%, 8 wt% of CaO, 10 wt% of BaO, 7 wt% of SrO and 5 wt% of ZnO. ₂ -Al ₂ O ₃ -B ₂ O ₃ -An RO glass was prepared.
[0055]
The above SiO ₂ -Al ₂ O ₃ -B ₂ O ₃ The -RO glass had a transition point of 630 ° C and a yield point of 680 ° C.
The measuring method and measuring device of the transition point and the yield point are the same as those in the first embodiment.
[0056]
Next, as in Example 1, 90 parts by weight of the silver powder and SiO ₂ -Al ₂ O ₃ -B ₂ O ₃ -RO glass was mixed with 10 parts by weight to obtain a mixture. To 100 parts by weight of this mixture, 30 parts by weight of an acrylic resin as an organic binder was added and mixed. Further, in the same manner as in Example 1, the mixture to which the organic binder was added was printed on transfer paper by two-plate printing to form a heat-generating metal composition layer.
[0057]
Next, as the lead-free coated glass composition layer, SiO 2 was used. ₂ -Al ₂ O ₃ -B ₂ O ₃ -An RO glass was prepared. This SiO ₂ -Al ₂ O ₃ -B ₂ O ₃ The -RO glass has the same composition as the lead-free glass of this example, and has a transition point of 630 ° C and a yield point of 680 ° C.
This SiO ₂ -Al ₂ O ₃ -B ₂ O ₃ -RO glass was laminated and printed on the heat-generating metal composition layer in the same manner as in Example 1 to form a lead-free coated glass composition layer. The printing was performed by two-plate printing, and the thickness of the lead-free coated glass composition layer was 30 μm.
[0058]
Subsequently, a film was coated on the lead-free coated glass composition layer in the same manner as in Example 1 to produce a lead-free heating film for electromagnetic cooking.
[0059]
Next, in the same manner as in Example 1, the above-described lead-free heating film for electromagnetic cooking was transferred to the inner bottom of a ceramic pot.
Subsequently, the ceramic pot was fired at 830 ° C. for 10 minutes. During the firing, the film of the lead-free heating film for electromagnetic cooking disappeared. Thus, a container for electromagnetic cooking was prepared, and this was used as Sample E2. Note that the thickness of the lead-free coated glass layer in Sample E2 was 17 μm.
[0060]
(Comparative Example 1)
This example is an example in which the composition of the lead-free glass of Example 1 and Example 2 was changed to produce a lead-free heating film for electromagnetic cooking and a container for electromagnetic cooking.
First, silver powder was prepared as a metal of the heat generating metal composition layer. The lead-free glass of the heat-generating metal composition layer may be SiO 2. ₂ 13 wt%, Al ₂ O ₃ 5 wt%, B ₂ O ₃ Containing 27 wt%, 5 wt% of CaO, 40 wt% of BaO, and 10 wt% of SrO ₂ -Al ₂ O ₃ -B ₂ O ₃ -An RO glass was prepared.
[0061]
The above SiO ₂ -Al ₂ O ₃ -B ₂ O ₃ The -RO glass had a transition point of 580 ° C and a yield point of 640 ° C.
The measuring method and measuring device of the transition point and the yield point are the same as those in the first embodiment.
[0062]
Next, in the same manner as in Examples 1 and 2, 90 parts by weight of the silver powder and SiO ₂ -Al ₂ O ₃ -B ₂ O ₃ -RO glass was mixed with 10 parts by weight to obtain a mixture. To 100 parts by weight of this mixture, 30 parts by weight of an acrylic resin as an organic binder were added and mixed. Further, in the same manner as in Example 1, a heat-generating metal composition layer was formed on the transfer paper by two-plate printing.
[0063]
Next, as the lead-free coated glass composition layer, SiO 2 was used. ₂ -Al ₂ O ₃ -B ₂ O ₃ -An RO glass was prepared. This SiO ₂ -Al ₂ O ₃ -B ₂ O ₃ The -RO glass has the same composition as the lead-free glass of this example, and has a transition point of 580 ° C and a yield point of 640 ° C.
This SiO ₂ -Al ₂ O ₃ -B ₂ O ₃ -RO glass was laminated and printed on the heat-generating metal composition layer in the same manner as in Examples 1 and 2 to form a lead-free coated glass composition layer. Printing was performed by two-plate printing, and the thickness of the lead-free coated glass composition layer was 28 μm.
[0064]
Subsequently, a film was coated on the lead-free coated glass composition layer in the same manner as in Examples 1 and 2, to produce a lead-free heating film for electromagnetic cooking.
[0065]
Next, in the same manner as in Examples 1 and 2, the above-described lead-free heating film for electromagnetic cooking was transferred to the inner bottom of a ceramic pot.
Subsequently, the ceramic pot was fired at 830 ° C. for 10 minutes. During the firing, the film of the lead-free heating film for electromagnetic cooking disappeared. Thus, a container for electromagnetic cooking was prepared, and this was used as Sample C1. Note that the thickness of the lead-free coated glass layer in Sample C1 was 15 μm.
[0066]
(Comparative Example 2)
This example is an example in which the composition of the lead-free glass of Examples 1, 2 and 3 was changed to produce a lead-free heating film for electromagnetic cooking and a container for electromagnetic cooking.
First, silver powder was prepared as a metal of the heat generating metal composition layer. The lead-free glass of the heat-generating metal composition layer may be SiO 2. ₂ 55 wt%, Al ₂ O ₃ 20 wt%, B ₂ O ₃ Containing 15 wt%, 5 wt% of CaO, and 5 wt% of ZnO ₂ -Al ₂ O ₃ -B ₂ O ₃ -An RO glass was prepared.
[0067]
The above SiO ₂ -Al ₂ O ₃ -B ₂ O ₃ The -RO glass had a transition point of 710 ° C and a yield point of 780 ° C.
The measuring method and measuring device of the transition point and the yield point are the same as those in the first embodiment.
[0068]
Next, in the same manner as in Examples 1 and 2, 90 parts by weight of the silver powder and SiO ₂ -Al ₂ O ₃ -B ₂ O ₃ -RO glass was mixed with 10 parts by weight to obtain a mixture. 30 parts by weight of an acrylic resin as an organic binder was added to 100 parts by weight of this mixture. Further, in the same manner as in Example 1, a heat-generating metal composition layer was formed on the transfer paper by two-plate printing.
[0069]
Next, as the lead-free coated glass composition layer, SiO 2 was used. ₂ -Al ₂ O ₃ -B ₂ O ₃ -An RO glass was prepared. This SiO ₂ -Al ₂ O ₃ -B ₂ O ₃ The -RO glass has the same composition as the lead-free glass of this example, and has a transition point of 710 ° C and a yield point of 780 ° C.
This SiO ₂ -Al ₂ O ₃ -B ₂ O ₃ -RO glass was laminated and printed on the heat-generating metal composition layer in the same manner as in Examples 1 and 2 to form a lead-free coated glass composition layer. The printing was performed by two-plate printing, and the thickness of the lead-free coated glass composition layer was 25 μm.
[0070]
Subsequently, a film was coated on the lead-free coated glass composition layer in the same manner as in Examples 1 and 2, to produce a lead-free heating film for electromagnetic cooking.
[0071]
Next, in the same manner as in Examples 1 and 2, the above-described lead-free heating film for electromagnetic cooking was transferred to the inner bottom of a ceramic pot.
Subsequently, the ceramic pot was fired at 830 ° C. for 10 minutes. During the firing, the film of the lead-free heating film for electromagnetic cooking disappeared. Thus, a container for electromagnetic cooking was prepared, and this was used as Sample C2. The thickness of the lead-free coated glass layer in Sample C2 was 13 μm.
[0072]
(Conventional example)
In this example, an example is shown in which a heating film for electromagnetic cooking and a container for electromagnetic cooking are manufactured using leaded glass.
First, silver powder was prepared as a metal of the heat generating metal composition layer. Further, instead of the lead-free glass of the heat-generating metal composition layer in Examples 1 and 2, PbO was 50 wt%, ₂ 25 wt%, Al ₂ O ₃ 5 wt%, B ₂ O ₃ Of lead-containing glass containing 20 wt%.
[0073]
The leaded glass had a transition point of 450 ° C. and a yield point of 570 ° C.
The measuring method and measuring device of the transition point and the yield point are the same as those in the first embodiment.
[0074]
Next, similarly to Examples 1 and 2, 90 parts by weight of the silver powder and 10 parts by weight of the leaded glass were mixed to obtain a mixture. To 100 parts by weight of this mixture, 30 parts by weight of an acrylic resin as an organic binder was added and mixed. The mixture to which this organic binder was added was printed on transfer paper by one-plate printing using a 250-mesh stainless steel plate to form a heat-generating metal composition layer.
[0075]
Next, SiO ₂ 60 wt%, Al ₂ O ₃ 5 wt%, B ₂ O ₃ 20 wt%, Na ₂ A glass containing 10 wt% of O and 5 wt% of ZnO was prepared.
This glass was laminated and printed on the heat-generating metal composition layer in the same manner as in Examples 1 and 2, to form a coated glass layer. The printing was performed by two-plate printing, and the thickness of the coating glass layer was 20 μm.
[0076]
Subsequently, in the same manner as in Examples 1 and 2, a film was coated on the above-mentioned coated glass layer to produce a heating film for electromagnetic cooking.
[0077]
Next, in the same manner as in Examples 1 and 2, the heating film for electromagnetic cooking was transferred to the bottom inside the ceramic pot.
Subsequently, the ceramic pot was fired at 830 ° C. for 10 minutes. During the firing, the film of the heating film for electromagnetic cooking disappeared. In this way, a container for electromagnetic cooking was prepared, and this was used as Sample C3. In addition, the thickness of the coating glass layer in Sample C3 was 9 μm.
[0078]
(Experimental example)
With respect to the samples E1, E2, and C1 to C3, the gloss after firing was visually observed. The observation was performed by comparing with a sample C3 which is a conventional product.
The thickness of the lead-free coated glass layer and the coated glass layer after firing were measured using an electron microscope.
Table 1 shows the results.
[0079]
Next, 1500 cc of water was poured into the five types of electromagnetic cooking containers of the samples E1, E2, and C1 to C3, and placed in a high-output electromagnetic cooker (HT-32CB, manufactured by Hitachi, Ltd.) compatible with 200V. After installation, the time until 1500 cc of water was completely boiled at an output of 1800 W was measured. Next, air heating was performed for 15 minutes, and after the air heating, changes in the lead-free coated glass layer and the coated glass layer in each sample were visually observed. The above-mentioned five types of electromagnetic cooking containers used in this experimental example are of the same shape with a capacity of 2000 cc.
Table 1 shows the results.
[0080]
[Table 1]

[0081]
As can be seen from Table 1, the surface gloss of the samples E1 and E2 of the present invention was superior to the conventional product (sample C3). On the other hand, in the sample C1, a part of the coated glass was foamed. Sample C2 was matte and lacked in gloss, and a part of the surface was peeled off. The lead-free coated glass layers of the samples E1 and E2 have a sufficient thickness of 10 μm or more. Therefore, it has excellent durability. On the other hand, since the thickness of sample C3 is only 9 μm, the lead-free coated glass layer is liable to be worn, and the life of the heat generating film may be shortened.
[0082]
The samples E1 and E2 were prepared by boiling 1500 cc of water within a short period of time of less than 5 minutes. It was excellent as well as heat resistance. On the other hand, Samples C1 to C3 had a portion that was peeled or melted in a part of the coating glass layer after the empty firing, and had low heat resistance. In addition, since sample C3 contains lead harmful to the human body, there was a problem in safety.
[Brief description of the drawings]
FIG. 1 is an explanatory view showing a lead-free heating film for electromagnetic cooking according to a first embodiment.
FIG. 2 is an explanatory view showing the electromagnetic cooking container according to the first embodiment.
FIG. 3 is a cross-sectional view of the electromagnetic cooking container of FIG. 2 taken along line AA.
[Explanation of symbols]
1. . . Lead-free heating film for electromagnetic cooking,
15. . . Heating metal composition layer,
152. . . Lead-free coated glass composition layer,
2. . . Induction cooking containers,
23. . . Lead-free heating film,
25. . . Heating metal layer,
252. . . Lead-free coated glass layer,

Claims

A lead-free heat generating film for electromagnetic cooking for sticking to a container and firing to form an electromagnetic cooking container capable of electromagnetic cooking,
The above-mentioned lead-free heat generating film for electromagnetic cooking has a metal composition layer for heat generation on the back surface side and a lead-free coated glass composition layer laminated on the front side,
The heat-generating metal composition layer is made of a mixture of a metal made of gold, silver, or platinum, a lead-free glass, and an organic binder,
The mixing ratio of the metal and the lead-free glass is 85 to 99 parts by weight of the metal and 1 to 15 parts by weight of the lead-free glass when both are 100 parts by weight.
The lead-free glass and the lead-free coated glass composition layer have a transition point of 550 ° C to 700 ° C and a sag point of 650 ° C to 750 ° C.

2. The lead-free heat generating film for electromagnetic cooking according to claim 1, wherein the thickness of the lead-free coated glass composition layer is 20 [mu] m or more.

The lead-free heating film for electromagnetic cooking according to claim 1 or 2, wherein the lead-free heating film for electromagnetic cooking can be fired at 800 to 900 ° C.

In any one of claims 1 to 3, the lead-free glass and lead-free coated glass composition layer _is _{_{_{_{SiO 2 -Al 2 O 3 -B 2}}}} O 3 -RO based glass (R, Ca, Sr, Ba, or one or more selected from Mg) made of, the _{_{_{_{SiO 2 -Al 2 O 3 -B 2}}}} O 3 in -RO based glass 100wt% _B 2 _{O 3} and 3~25wt%, 10~55wt% containing RO A lead-free heating film for electromagnetic cooking, characterized in that:

An electromagnetic cooking container having a lead-free heating film formed on the surface of the container,
The lead-free heat-generating film is composed of a heat-generating metal layer bonded to the container side and a lead-free coated glass layer provided on the surface of the heat-generating metal layer.
The heating metal layer is composed of 85 to 99 parts by weight of a metal made of gold, silver, or platinum and 1 to 15 parts by weight of lead-free glass.
The container for electromagnetic cooking, wherein the lead-free glass and the lead-free coated glass layer have a transition point of 550 ° C to 700 ° C and a sag point of 650 ° C to 750 ° C.

The lead-free heating film for electromagnetic cooking according to claim 5, wherein the thickness of the lead-free coated glass layer is 10 µm or more.

According to claim 5 or 6, the lead-free glass and lead-free coated glass _{_{_{_{layer, SiO 2 -Al 2 O 3 -B}}}} 2 O 3 -RO based glass (wherein, R is selected Ca, Sr, Ba, or the Mg 1 or more) made of, the _{_{_{_{SiO 2 -Al 2 O 3 -B 2}}}} O 3 -RO based 3～25Wt% in the glass 100 wt% of _B 2 _{O 3,} and characterized in that the RO containing 10～55Wt% Container for electromagnetic cooking.