JP3559449B2 - Orthorhombic hydroxide phosphor and its manufacturing method - Google Patents

Description

【００１２】
（但し、式中の□は組成欠陥、Ｍはマグネシウム、カルシウム、ストロンチウム及びバリウムから選択された一種類以上のアルカリ土類金属元素、Ｍ^＊ はマンガン、亜鉛から選択された一種類以上の２価金属元素、ＬｎはＥｕ以外の一種類以上の希土類元素を表し、ｎ、ｍ、ｌ、αは、それぞれ下記の範囲を満足する数値からなる。
０≦ｎ≦０．２
０＜α＜０．５
０．０００１≦ｍ≦０．１
０．０００１≦ｌ≦０．１ ）
で表される水熱合成による水酸化物ＳｒＡｌ_３ Ｏ_５（ＯＨ） の斜方晶系構造を有する蓄光体として構成され、それを単一相、それを含む混合相、又は該斜方晶系構造で結晶性の低い相からなるＥｕ^２＋を賦活したものとして構成できるものである。
【００１３】
上記蓄光体は、電子線、２２０ｎｍ〜４５０ｎｍの範囲にある紫外線又は可視光、あるいはそれらの複数により励起後、室温もしくは少なくとも室温以上の温度域に加熱昇温する時に、熱ルミネッセンス（蛍光）の性質を維持するものであり、耐水性に優れ、微粒子または結晶性の低いごく微粒なものでも高輝度長残光性の青緑色発光を行うものである。
【００１４】
また、本発明に係る上記斜方晶系水酸化物蓄光体の製造方法は、水熱反応の出発原料として、上記組成式（１） 又は（２） におけるＭを含む化合物、Ｍ^＊ を含む化合物、Ａｌを含む化合物、Ｓｉを含む化合物、Ｅｕ^２＋を含む化合物及びＬｎを含む化合物を用い、それらの水熱合成により水熱反応を経て得られた上記組成式におけるＥｕ^２＋を賦活することによって行われるものである。
【００１５】
更に具体的に説明すると、本発明に係る斜方晶系構造を有するＥｕ^２＋を賦活した高輝度長残光性水酸化物蓄光体の製造においては、上記Ｍ元素を含む化合物、Ｍ^＊ 元素を含む化合物、Ａｌ元素を含む化合物、Ｓｉ元素を含む化合物、Ｅｕ及びＬｎを含む化合物を、
【数３】

【００１６】
（但し、式中の□、Ｍ、Ｍ^＊ 及びＬｎについては同上。ｎ、ｍ、ｌ、ｚ、αは、それぞれ下記の範囲を満足する数値からなる。
０≦ｎ≦０．２
０．８≦ｚ≦２．０
０≦α＜０．５
０．０００１≦ｍ≦０．１
０．０００１≦ｌ≦０．１ ）
【００１７】
で表わされる組成式の割合で混合した原料粉末を、炭酸ナトリウム又は酸化ホウ素と共に、還元性雰囲気において１０００〜１４００℃の条件で焼成した後、粉砕し、原料としてのスラリーを調製する。又は、Ｍ^２＋を含む化合物、Ｍ^＊２＋ を含む化合物、Ａｌ^３＋を含む化合物、Ｓｉ^４＋を含む化合物、Ｅｕ^２＋を含む化合物、Ｌｎ^３＋を含む化合物を、所定比（組成式（１） 又は（２） で示す化合物になるように）で混合し、スラリーを調製する。
これらのスラリーは、スラリー濃度が１０ｗｔ％〜６０ｗｔ％にあり、溶液のｐＨが、２．０〜１２．０になるように調整する。ｐＨの調整には、ＮａＯＨ，ＮＨ_４ ＯＨ，ＨＣｌ，ＨＮＯ_３ ，Ｈ_３ ＰＯ_４ ，ＮａＦ、その他、溶液中のＨ^＋ ，ＯＨ⁻ 有効イオン濃度を調整できるものを用いることができる。
【００１８】
水熱合成は、オートクレーブ等の高温高圧化学反応容器において、１００℃〜５００℃の温度で、５００ｋｇ／ｃｍ^２ までの圧力で、１〜４８時間反応を行わせることができる。得られた生成物は、それを洗浄、濾過し、８０〜１００℃で乾燥することにより、上記微粒子または結晶性の低いごく微粒な高輝度長残光性水酸化物蓄光体を得る。
【００１９】
【発明の実施の形態】
本発明の高輝度長残光性水酸化物蓄光体は、水酸化物ＳｒＡｌ_３ Ｏ_５（ＯＨ） の斜方晶系構造を有し、若しくは該斜方晶系構造で結晶性の低い微粒子のＥｕ^２＋を賦活してなり、耐水性に優れ、微粒子または結晶性の低い微粒においても高輝度長残光性を示し、電子線、２２０〜４５０ｎｍの範囲の紫外線、可視光、あるいはそれらの複数による励起後に、当該蓄光体を室温もしくは室温以上に加熱昇温するときに、熱ルミネッセンス（蛍光）を示すものである。
【００２０】
更に具体的に説明すると、蓄光体の母体構成成分は、組成式が、前記（１） 又は（２） 式で表されるもので、構成成分中にあるアルカリ土類金属元素Ｍ（特に、Ｍ＝Ｓｒがもっとも良い。）の一部を、２価金属元素Ｍ^＊ で示すマンガンあるいは亜鉛置換すると、残光特性は低下するが、発光輝度を向上させることができる。Ｍ^＊ 置換量ｎ（モル値）は、０≦ｎ≦０．２、好ましくは、０≦ｎ≦０．０５の範囲とするのがよく、これにより所望の条件を満足するが、０．２を超えて置換すると、残光性のみならず発光輝度の向上の効果が低くなる。
【００２１】
また、高輝度長残光性水酸化物蓄光体に含まれるＥｕ^２＋の組成を決める前記ｍの値は、０．０００１≦ｍ≦０．１、好ましくは０．００１≦ｍ≦０．０１であることが望まれ、ｍが０．０００１未満では発光中心となるイオン量が少なく、十分な発光輝度が得られないことを確かめている。また、ｍが０．１を超えると発光中心イオン間の相互作用に伴う濃度消光が起こるとともに、目的以外の化合物の副生成物が生じ、得られた蓄光体粉末の輝度が著しく低下する。
Ｅｕ^２＋と共に、賦活剤としてＤｙ^３＋やＹ^３＋などの希土類元素Ｌｎを用いる場合には、前記ｌの値は、０．０００１≦ｌ≦０．１、好ましくは０．００１≦ｌ≦０．０３が適している。特に、例えば、Ｅｕ^２＋とＤｙ^３＋とＹ^３＋のように三つ又はそれ以上の希土類元素を共用すると、高輝度長残光性の効果が大きい。
【００２２】
組成式中のＳｉＯ_２ ないしケイ素の含有量を決める前記αの値（モル値）は、０＜α≦０．５の範囲にあり、固溶するＳｉ量の増加に伴って電荷収支をとる必要から、□で表している母体構成組成に欠損が生ずる。この欠陥構造の形成が蓄光体の発光輝度、残光特性に寄与できる。そこで、０．００１≦α≦０．２５の範囲が好ましく、この範囲、特に上記０＜α≦０．５を超えると残光特性と輝度が低下する。また、組成式中のＳｉＯ_２ の量が多くなると、蓄光体の発光の挙動が明らかに変化し、最大発光波長がさらに紫外域にシフトする。
【００２３】
水熱反応の出発原料を高温焼結する際に、フラックスとして加えるホウ酸は、一部Ａｌ元素と固溶置換して、残光性を改善することがあるが、その置換量は、０．００１モルを超えることはない。また、過剰のホウ酸が存在しても、未反応量が増えるのみで、水熱反応の時、これが溶液中に溶け出し、粒成長の促進に関わる。よって、微粒子の水熱反応生成物を得るには過剰のホウ酸の含有する出発原料が好ましい。
【００２４】
上記高温焼結した蓄光体は、３００μｍ以下に粉砕し、水溶液中に入れ、スラリー濃度が１０ｗｔ％〜６０ｗｔ％に、溶液のｐＨが２．０〜１２．０になるように調整する。スラリー濃度がこれより低いと、反応物濃度が薄いため、反応性が悪く、収率も少ない。逆に、これより高いと、撹拌に対する摩擦が大きくなったり、反応が不充分になったり、反応時間が長くなる。また、ｐＨは５〜１０が特に好ましい。この範囲で合成されたものは、最も微粒化され、輝度も残光性もよい。ｐＨ調整には、ＮａＯＨ，ＮＨ_４ ＯＨ，ＨＣｌ，ＨＮＯ_３ ，Ｈ_３ ＰＯ_４ ，ＮａＦ，その他の溶液中のＨ^＋ ，ＯＨ⁻ 有効イオン濃度を調整できる酸ないしはアルカリの内、どれを用いても良く、また複数のものを組み合わせて用いても構わない。また、ｐＨ調整をしなくても、水熱反応を行った結果は、斜方晶系構造に帰属する水酸化物を合成できる。
得られた水酸化物の生成物については、ｐＨ調整の時導入した余分なＮａ^＋ ，Ｃｌ⁻ ，Ｆ⁻ などのイオンを洗浄、濾過するのが望ましいが、洗浄しなくても、輝度と残光特性に大きな影響を与えない。微粒な斜方晶結晶の凝集や粒成長を防ぐには、これらを８０〜１００℃で乾燥することが好ましい。
【００２５】
本発明の高輝度長残光性水酸化物蓄光体は、一般的には、次のようにして合成される。
Ｍ元素を含む化合物、Ｍ^＊ 元素を含む化合物、Ａｌ元素を含む化合物、Ｓｉ元素を含む化合物ないしケイ素、及びＥｕ元素を含む化合物を、前記組成式の所定量での割合で混合し、得られた原料粉末を、一旦還元性雰囲気において１０００〜１４００℃の条件で焼成した後、３００μｍ以下に粉砕して水熱合成の原料とする。
次に、粉砕した蓄光体粉末を水溶液に入れ、スラリー濃度を１０ｗｔ％〜６０ｗｔ％に、溶液のｐＨを２．０〜１２．０に調整する。水熱合成は、一般的には、高温高圧化学反応容器（オートクレーブ）を用いて、１００℃〜５００℃の温度、５００ｋｇ／ｃｍ^２ までの圧力で、１〜４８時間反応させる。この水熱合成は、以下の実施例では、自生圧において行っているが、通常の量産において用いられる各種手段、例えばアルゴンガスを圧縮して導入するなどの手段を用いて、５００ｋｇ／ｃｍ^２ またはそれ以上（例えば、２０００ｋｇ／ｃｍ^２ 程度まで）に加圧して反応を促進させ、反応時間を短縮させることができる。得られた生成物は、洗浄、濾過し、８０〜１００℃で乾燥することにより所期の蓄光体を得る。この蓄光体は、それを単一相、それを含む混合相等として利用できるものである。
【００２６】
本発明の高輝度長残光性水酸化物蓄光体は、上記水熱合成により、さらに表面改質することができる。たとえば、インクや塗料に混合する際に求められる溶液中の安定性、施工性として、水酸化物蓄光体を有機複合化することにより、有機系溶媒においても分散性を改善できる。
また、本発明の実施例等で得られた蓄光体の平均粒子径は７．６〜９．３μｍ程度であり、これはインク等において要求されている１０μｍ以下を達成できるものである。
【００２７】
得られた水酸化物蓄光体粉末についての各種性能測定においては、蓄光体：ポリエステル樹脂を、１：２（重量比）の割合で均一混合したものを、シート状等に成型、乾燥し、試料とした。これを光遮断２４時間後、１５Ｗ白色蛍光灯を用いて、１００ｍｍの距離で３０分間試料を照射し、暗室にてその発光強度の経時変化を測定した。
【００２８】
【実施例】
以下に実施例を示し、更に詳しくこの発明について説明する。
［実施例１］
Ｓｒ_{０．９８２} Ｅｕ_{０．００５} Ｄｙ_{０．００８} Ｙ_{０．００５} Ａｌ_{２．９７０} Ｓｉ_{０．０２２} Ｏ_５ （ＯＨ）の水酸化物蓄光体を得るために、後述する比較例１の場合と同じ化学組成（Ｓｒ_{０．９８２} Ｅｕ_{０．００５} Ｄｙ_{０．００８} Ｙ_{０．００５} ）Ｏ・１．５（Ａｌ_１．９８Ｓｉ_{０．０１５} Ｏ_３ ）をもつ３００μｍ以下の粉末状蓄光体５０ｇを出発原料として、それを蒸留水２００ｍｌ中に入れ、希硝酸を添加し、スラリーのｐＨを６．０に調整した後、高温高圧化学反応容器（オートクレーブ）を用いて、１５０℃で、２時間、自生圧８．６ｋｇ／ｃｍ^２ で水熱反応させた。得られた生成物を洗浄、濾過し、８０℃で乾燥した。
【００２９】
乾燥した粉末につき、粉末Ｘ線回折法による相同定を行った。図１に、ＣｕＫα線による粉末Ｘ線回折のパターンを示す。また、表１に水熱生成物の粉末Ｘ線回折での格子面間隔値を示す。これは斜方晶構造を持つＳｒＡｌ_３ Ｏ_５ ＯＨ化合物に同形であり、格子定数を求めた結果、ａ＝８．５１８Å，ｂ＝２４．６７０Å，ｃ＝４．８９６Åとなった。
【００３０】
【表１】

【００３１】
この水酸化物蓄光体について、２４０ｎｍの紫外線により励起した試料の発光スペクトルを測定したところ、水熱前の出発原料と同じ、最大発光強度を与えるピークは４８６ｎｍ付近に位置し、青緑色に発光した。
表２に、水熱前の蓄光体粉末の嵩密度、発光強度、ＢＥＴ比表面積を１００とした場合の水熱後の各々の相対値を示す。この表２のＣに示すように、水熱処理後には、水熱処理前の蓄光体と比べ、ごく細かく、嵩密度が半分以下になり、ＢＥＴ比表面積が２０倍程度大きくなることがわかった。
【００３２】
【表２】

【００３３】
［実施例２］
Ｓｒ_{０．９８２} Ｅｕ_{０．００５} Ｄｙ_{０．００８} Ｙ_{０．００５} Ａｌ_３ Ｏ_５（ＯＨ） の水酸化物蓄光体を得るために、後述する比較例２の場合と同じ化学組成（Ｓｒ_{０．９８２} Ｅｕ_{０．００５} Ｄｙ_{０．００８} Ｙ_{０．００５} Ａｌ_２ Ｏ_４ ）をもつ６３μｍ以下の粉末状蓄光体５０ｇを出発原料として、それを蒸留水２００ｍｌ中に入れ、稀塩酸を添加してスラリーのｐＨを８．３に調整した後、高温高圧化学反応容器（オートクレーブ）を用いて、２００℃で、１０時間、自生圧１１．３ｋｇ／ｃｍ^２ で水熱反応させた。得られた生成物が、白色のものと、黄色の粒子状のものに別れたので、これを分離、洗浄、濾過し、８０℃で乾燥した。
【００３４】
上記の乾燥でできた２種類の粉末について、粉末Ｘ線回折法による相同定を行った。
図２の（ｂ）に白色状の、同図（ｃ）に黄色粒子状の生成物の、ＣｕＫα線による粉末Ｘ線回折のパターンを示す。また、比較のため、水熱前の粉末Ｘ線回折のパターンを図２の（ａ）に示す。黄色の粒子状の生成物は、立方晶系のＳｒ_３ Ａｌ_２（ＯＨ）_１２ に帰属する。そして、図２の（ｂ）に示すように、白色のものが斜方晶系構造に属するＳｒ_{０．９８２} Ｅｕ_{０．００５} Ｄｙ_{０．００８} Ｙ_{０．００５} Ａｌ_３ Ｏ_５（ＯＨ） の結晶性の低い微粒子であり、（ｈｋｌ）が（０２０）のピークにおいて、２θが１１度〜１７度に及ぶことがわかった。
【００３５】
また、この白色の微粒子について、赤外吸収とＴＧ分析を行った。その赤外吸収結果を図３に、ＴＧ分析結果を図４（ｂ）に示す。比較のため、水熱前のＴＧ分析結果を図４の（ａ）に示す。図３の赤外吸収では、ＯＨ基の挙動が確認できた。また、図４では、白色の微粒子試料における４００℃〜５００℃の間での水酸化物の脱水が観察された。
図５の（ａ）に白色の微粒子試料のＳＥＭ写真を、図５の（ｂ）に水熱前の試料のＳＥＭ写真を示す。これらの写真に示すように、本発明の水熱合成により得られた水酸化物蓄光体は、固相反応で得られないほどの微粒子であり、その凝集体の平均粒径が７．６μｍであった。
【００３６】
上記両粒子の発光強度の経時変化を測定したところ、白色の斜方晶構造に属するＳｒ_{０．９８２} Ｅｕ_{０．００５} Ｄｙ_{０．００８} Ｙ_{０．００５} Ａｌ_３ Ｏ_５（ＯＨ） の微粒子は良く発光したが、立方晶系の黄色の粒子（Ｓｒ，Ｅｕ，Ｄｙ，Ｙ）_３ Ａｌ_２（ＯＨ）_１２ には弱々しい発光しか見られなかった。
また、前記表２のＡに示すように、水熱後の相対嵩密度、相対発光強度、相対ＢＥＴ比表面積は、水熱前の蓄光体と比べて、ごく細かく、嵩密度が１１．５％になり、ＢＥＴ比表面積が１５５．３ｍ^２ ／ｇとなり、３００倍ほど大きくなった。
【００３７】
更に、図６の（ａ）として、白い微粒子の励起スペクトルを示し、２４０ｎｍの紫外線により励起した同試料の発光スペクトルを図６の（ｂ）として示す。比較のために、水熱前の励起スペクトルと、２５０ｎｍの紫外線により励起した同試料の発光スペクトルを図７の（ａ）及び（ｂ）に示す。
これらの図より、水熱前の試料は最大発光強度を与えるピークが５１３ｎｍにあるのに対して、水熱後の白い微粒子では最大発光強度を与えるピークが４８６ｎｍ付近に位置する青緑色発光であることがわかる。
【００３８】
［実施例３］
後述する比較例３で得られた１０６μｍ以下の粉末状蓄光体５０ｇを出発原料として、それを蒸留水２００ｍｌに入れ、ｐＨを調整しないまま、高温高圧化学反応容器（オートクレーブ）を用いて、１８０℃、５時間自生圧で水熱反応を行った。得られた生成物を洗浄、濾過し、８０℃で乾燥してた。
【００３９】
乾燥した種類の粉末を粉末Ｘ線回折法による相同定を行った。図８に、ＣｕＫα線による粉末Ｘ線回折のパターンを示し、表３にその格子面間隔距離を示す。これも斜方晶構造を持ち、格子定数がａ＝８．５１２Å，ｂ＝２４．７８８Å，ｃ＝４．８９３Åとなった。
この水酸化物蓄光体は、２４０ｎｍの紫外線により励起した試料の発光スペクトルを測定したところ、最大発光強度を与えるピークは、４８５ｎｍ付近に位置する青緑色発光性蓄光体である。
また、前記表２のＢに示すように、水熱前の蓄光体と比べ、ごく細かく、嵩密度が３分の１以下になった。
【００４０】
【表３】

【００４１】
［実施例４］ 耐水テスト
耐水性については、実施例と比較例の３０μｍ以下に粉砕した蓄光体粉末を各１０ｇ秤量し、それを容量３００ｍｌのビーカーに２００ｍｌの蒸留水とともに入れ、マグネットスタラーで２時間撹拌し、４０℃、８０℃で１００時間を保持した。その温水処理前後における輝度を測定し、輝度の減少率を求めた。その結果に関し、温水処理前の輝度を１００とした場合の温水処理後の相対輝度を表４に示す。温水処理後の輝度がほぼ変わらず、水溶液中においても安定し、耐水性に優れることがわかった。
【００４２】
【表４】

【００４３】
［比較例１］
（Ｓｒ_{０．９８２} Ｅｕ_{０．００５} Ｄｙ_{０．００８} Ｙ_{０．００５} ）Ｏ・１．５（Ａｌ_１．９８Ｓｉ_{０．０１５} Ｏ_３ ）の化学組成をもつ蓄光体を得るために、フラックスとしてＨ_３ ＢＯ_３ を加え、下記の量の原料粉末を各々秤量した。次いで、適量の蒸留水を加え、ボールミルにて２０時間湿式混合した。
ＳｒＣＯ_３ ７２．４８０ｇ
Ａｌ_２ Ｏ_３ ７５．６９９ｇ
ＳｉＯ_２ ０．６７６ｇ
Ｅｕ_２ Ｏ_３ ０．４４０ｇ
Ｄｙ_２ Ｏ_３ ０．７４６ｇ
Ｙ_２ Ｏ_３ ０．２８２ｇ
Ｈ_３ ＢＯ_３ ７．５１５ｇ
【００４４】
それを１００℃で乾燥することによって得られた混合粉末を、１０００ｋｇ／ｃｍ^２ の荷重で、８０ｍｍ角の金型成型器を用いて成型し、これをアルミナ坩堝に入れ、電気炉を用いて３％水素含有アルゴンガス中、１３００℃で２時間焼成し、冷却した後、アルミナ乳鉢で細かく粉砕し、再び金型成型器を用いて成型し、一回目と同じ条件で再度焼成することにより蓄光体の試料を得た。
３６０ｎｍの紫外線により励起したこの試料の最大発光強度を与えるピークは、４９０ｎｍ付近に位置し、青緑色発光性蓄光体であることがわかった。
得られた青緑色発光性蓄光体を３００μｍ以下に粉砕し、水熱反応の原料とした。この比較例１の蓄光体の性質等については、実施例１等との比較において既に説明している。
【００４５】
［比較例２］
Ｓｒ_{０．９８２} Ｅｕ_{０．００５} Ｄｙ_{０．００８} Ｙ_{０．００５} Ａｌ_２ Ｏ_４ の化学組成をもつ蓄光体を、下記の通り作製した。フラックスとして、Ｈ_３ ＢＯ_３ を加え、下記の量の原料粉末を各々秤量し、適量の蒸留水を加えてボールミルにて２０時間湿式混合した。
ＳｒＣＯ_３ ７２．４８０ｇ
Ａｌ_２ Ｏ_３ ５０．９７９ｇ
Ｅｕ_２ Ｏ_３ ０．４４０ｇ
Ｄｙ_２ Ｏ_３ ０．７４６ｇ
Ｙ_２ Ｏ_３ ０．２８２ｇ
Ｈ_３ ＢＯ_３ ３．７０４ｇ
【００４６】
それを１００℃で乾燥することによって得られた混合粉末を、１０００ｋｇ／ｃｍ^２ の荷重で、８０ｍｍ角の金型成型器を用いて成型し、これをアルミナ坩堝に入れ、電気炉を用いて３％水素含有アルゴンガス中、１４００℃で２時間焼成し、冷却した後、アルミナ乳鉢で細かく粉砕することにより得られた。
図２（ａ）は、この合成した比較例２の粉砕Ｘ線回折を行った結果のＸＲＤパターンを示すものである。これは単斜晶系のスタッフドトリジマイト型構造に帰属するものである。
３６０ｎｍの紫外線により励起した試料の最大発光強度を与えるピークは、５１３ｎｍ付近に位置し、黄緑色発光性蓄光体であることがわかった。
得られた黄緑色発光性蓄光体は、６３μｍ以下に粉砕し、水熱反応の原料とした。この比較例２の蓄光体の性質等については、実施例との比較において既に説明している。
【００４７】
［比較例３］
（Ｓｒ_{０．９７２} Ｍｎ_０．０１Ｅｕ_{０．００５} Ｄｙ_{０．００８} Ｙ_{０．００５} ）Ｏ・１．２（Ａｌ_１．９２Ｓｉ_０．０６Ｏ_３ ）の化学組成をもつ蓄光体を、下記の通り作製した。フラックスとして、Ｈ_３ ＢＯ_３ を加え、下記の量の原料粉末を各々秤量し、適量の蒸留水を加えてボールミルにて２０時間湿式混合した。
ＳｒＣＯ_３ ７１．７４７ｇ
ＭｎＯ_２ ０．４３５ｇ
Ａｌ_２ Ｏ_３ ５８．７３０ｇ
ＳｉＯ_２ ２．１６３ｇ
Ｅｕ_２ Ｏ_３ ０．４４０ｇ
Ｄｙ_２ Ｏ_３ ０．７４６ｇ
Ｙ_２ Ｏ_３ ０．２８２ｇ
Ｈ_３ ＢＯ_３ ６．６３０ｇ
【００４８】
それを１００℃で乾燥することによって得られた混合粉末を、１０００ｋｇ／ｃｍ^２ の荷重で、８０ｍｍ角の金型成型器を用いて成型し、これをアルミナ坩堝に入れ、電気炉を用いて３％水素含有アルゴンガス中、１２８０℃で３時間焼成し、冷却した後、アルミナ乳鉢で細かく粉砕し、再び金型成型器を用いて成型し、一回目と同じ条件で再度焼成することにより比較例３の蓄光体試料を得た。
２４０ｎｍの紫外線により励起した試料の最大発光強度を与えるピークは、４９０ｎｍ付近に位置し、これが青緑色発光性蓄光体であることがわかった。
得られた青緑色発光性蓄光体を１０６μｍ以下に粉砕し、水熱反応の原料とした。この比較例３の蓄光体の性質等については、実施例との比較において既に説明している。
【００４９】
【発明の効果】
以上に詳述した本発明の高輝度長残光性水酸化物蓄光体によれば、比表面積が高温焼結の固相反応で得られた酸化物蓄光体より約１０〜３００倍大きく、特に耐水性が飛躍的に改善されて、水性溶液中の安定性が優れ、インクや塗料などの応用分野においても実用性に富むものである。
【図面の簡単な説明】
【図１】本発明の実施例１の蓄光体粉末Ｘ線回折パターンを示す線図である。
【図２】本発明の実施例２の蓄光体粉末Ｘ線回折パターンを示す線図で、（ａ）は水熱前、（ｂ）は水熱後の白色状の生成物、（ｃ）は水熱後の黄色粒子状の生成物の粉末Ｘ線回折パターンを示す線図である。
【図３】本発明の実施例２の白色試料の赤外吸収図である。
【図４】（ａ）は本発明の実施例２の白色試料の熱天秤分析図、（ｂ）は同実施例２の水熱合成前試料（比較例２）の熱天秤分析図である。
【図５】（ａ）は本発明の実施例２の白色試料の微粒子の、（ｂ）はその水熱前の試料についての図面代用の走査型電子顕微鏡写真である。
【図６】（ａ）は本発明の実施例２の白色試料の励起波長図、（ｂ）は同発光波長図である。
【図７】（ａ）は本発明の実施例２の水熱合成前試料の励起波長図、（ｂ）は同発光波長図である。
【図８】本発明の実施例３の試料の粉末Ｘ線回折パターンを示す線図である。[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a hydroxide SrAl₃  O₅Eu having a rhombic structure of (OH) 2 or having a low crystallinity having the rhombic structure²⁺And a method for producing the phosphorescent material by hydrothermal synthesis.
More specifically, the present invention is excellent in weather resistance, indoors and outdoors, even in a dark place such as underwater, electron beam, ultraviolet light, visible light, or exhibit a high luminance long afterglow when excited by a plurality thereof, In particular, hydroxide SrAl that has been made into fine particles in consideration of water resistance and practical effectiveness, and has dramatically improved specific surface area.₃  O₅Eu having fine particles having an orthorhombic structure of (OH) 2 or having low crystallinity having the orthorhombic structure²⁺TECHNICAL FIELD The present invention relates to a high-intensity and long-lasting phosphorescent material of main activation and a method for producing the same.
[0002]
[Prior art]
Phosphor refers to a substance that emits light by being excited by some external stimulus such as particle energy, electrons, or light, but a persistence luminous substance that can continue to emit light even after the excitation is stopped. It is called "luminous body". Such luminous bodies are required to be excellent in multicolor and long afterglow with the diversification of various displays and sophistication, and furthermore, practically, improvement of weather resistance is required.
[0003]
As inorganic materials, sulfide-based and oxyacid-based luminous bodies such as strontium aluminate have already been reported. Examples of the sulfide-based phosphor include, for example, blue-emitting (Ca, Sr) S: Bi.³⁺Phosphor, yellow-green emitting ZnS: Cu²⁺There are a phosphor and a red-emitting (Zn, Cd) S: Cu phosphor. On the other hand, as the oxyacid salt-based phosphor, for example, the chemical formula SrAl activated with Eu₂  O₄  Is a strontium aluminate (US Pat. No. 3,294,699, 1966), which is a yellow-green phosphor having a maximum emission intensity around 520 nm. In particular, SrAl having a stuffed tridymite structure reported in Journal of Electrochemical Society, Vol. 118, p. 930 (1971).₂  O₄  : Eu²⁺Phosphors exhibit long afterglow. Although this shows a much longer afterglow than the ZnS: Cu phosphor, it is pointed out that it does not satisfy the demands for excellent weather resistance and multicoloring.
[0004]
Further, Chinese Patent Publication No. CN1053807A (August 1991) discloses an aluminum strontium long afterglow fluorescent material. The composition formula is m (Sr_1-x ^*Eu_x ^*) OnAl₂  O₄  ・ YB₂  O₃  (Where 1 ≦ m ≦ 5, 1 ≦ n ≦ 8, 0.11 ≦ x^*  ≦ 0.1, 0.05 ≦ y ≦ 0.35).
Although these long afterglow phosphors have improved luminance, they are not sufficient for practical use as luminous bodies.
[0005]
In response to such a problem, the present inventor has been conducting various studies on an oxide containing an alkaline earth metal element in the periodic table and a luminous body having a new composition, mainly on an aluminum silicate compound. However, regarding a reaction product of an oxide containing a specific composition of an alkaline earth metal element and aluminum silicate,²⁺Activation or Eu²⁺And activation with Ln rare earth element, the composition formula becomes
(M_1-nml  M^* _nEu_m  Ln_l) (Al_1-x  Si_3/4  x  □_1/4  x)₂  O₄
(Where □ is a composition defect, M is one or more alkaline earth metal elements selected from magnesium, calcium, strontium and barium, M^*  Is one or more divalent metal elements selected from manganese and zinc, and Ln is one or more rare earth elements other than Eu). It has been found that a phosphorescent material can be obtained (Japanese Patent Application No. 9-238966).
[0006]
However, the above-mentioned phosphors and luminous bodies are consistent with the empirical rule that the emission luminance and the afterglow characteristic are related to the particle size distribution of the powder, and the smaller the particle size, the lower the emission luminance and the afterglow characteristic. . Furthermore, these phosphors and phosphorescent bodies are produced by solid-phase reaction after high-temperature sintering, and then pulverized and classified by mechanical means. There is a possibility that the light emission luminance and the afterglow characteristics are reduced.
In other words, in the following points, the above-mentioned phosphors and phosphorescent materials are not always satisfactory with respect to fine particles.
[0007]
1. Since these long-afterglow phosphors and phosphorescent bodies are obtained by sintering particles, practically, in most cases, they must be a sintered body or a pseudo-lumped sintered powder, which must be finely powdered. . Empirically, the emission luminance and the afterglow characteristic of the phosphor decrease as the particle diameter decreases, and in particular, particles with a diameter of 2 μm or less hardly emit light.
2. In the above pulverization process, the appearance color, emission luminance, and afterglow characteristics of the phosphor are often deteriorated due to the inclusion of impurities.
3. In an application field in which ink is used in a mixture with a coating material, a smooth surface is desired for fine printing, and a particle size of several microns is indispensable. At the same time, it must have high emission luminance, excellent water resistance, and be stable in organic or inorganic solvents.
[0008]
Industrially, especially from the technical fields related to printing, ink, and paint, there is a demand for a fine particle phosphor powder having a particle size of 10 μm or less without a decrease in emission luminance and afterglow characteristics.
[0009]
[Problems to be solved by the invention]
The inventor of the present invention crushes the phosphorescent material that has undergone the solid-phase reaction through high-temperature sintering to a certain particle size, and uses a high-temperature and high-pressure chemical reaction vessel such as an autoclave to perform a high-pressure hydrothermal treatment at a temperature of 100 ° C to 500 ° C in an aqueous solution. Various hydrothermal reaction experiments were conducted below, and as a result of intensive study, Eu belonging to the orthorhombic structure was obtained.²⁺It has been found that a hydroxide phosphor having activated therein is excellent in water resistance and emits blue-green light with high luminance and long persistence even if it is fine particles or extremely fine particles having low crystallinity.
[0010]
[Means for Solving the Problems]
The present invention is based on this finding and has an orthorhombic structure,²⁺The present invention provides a hydroxide phosphor having high luminance and long afterglow, which is composed of fine particles having excellent water resistance.
[0011]
That is, the orthorhombic hydroxide phosphor of the present invention basically has a composition formula:
(Equation 2)

[0012]
(Where □ in the formula is a composition defect, M is at least one kind of alkaline earth metal element selected from magnesium, calcium, strontium and barium, M^*  Represents one or more kinds of divalent metal elements selected from manganese and zinc, Ln represents one or more kinds of rare earth elements other than Eu, and n, m, l, and α are numerical values satisfying the following ranges, respectively. .
0 ≦ n ≦ 0.2
0 <α <0.5
0.0001 ≦ m ≦ 0.1
0.0001 ≦ l ≦ 0.1)
Represented byBy hydrothermal synthesisHydroxide SrAl₃  O₅Eu which is constituted as a phosphorescent substance having an orthorhombic structure of (OH) 2, which is composed of a single phase, a mixed phase containing the same, or a phase having the orthorhombic structure and low crystallinity.²⁺Is activated.
[0013]
The luminous body has a property of thermoluminescence (fluorescence) when heated to room temperature or at least room temperature after being excited by an electron beam, ultraviolet light or visible light in the range of 220 nm to 450 nm, or a plurality thereof. It is excellent in water resistance and emits blue-green light with high luminance and long afterglow even if it is fine particles or very fine particles having low crystallinity.
[0014]
Further, in the method for producing an orthorhombic hydroxide phosphor according to the present invention, the compound containing M in the composition formula (1) or (2) may be used as a starting material for the hydrothermal reaction.^*  , A compound containing Al, a compound containing Si, Eu²⁺And a compound containing Ln, and Eu in the above composition formula obtained through a hydrothermal reaction by their hydrothermal synthesis.²⁺This is performed by activating.
[0015]
More specifically, Eu having an orthorhombic structure according to the present invention is described.²⁺In the production of a high-luminance long afterglow hydroxide phosphor having activated therein, the compound containing the above-mentioned M element,^*  A compound containing an element, a compound containing an Al element, a compound containing a Si element, a compound containing Eu and Ln,
(Equation 3)

[0016]
(However, □, M, M^*  And Ln. n, m, l, z and α are numerical values satisfying the following ranges, respectively.
0 ≦ n ≦ 0.2
0.8 ≦ z ≦ 2.0
0 ≦ α <0.5
0.0001 ≦ m ≦ 0.1
0.0001 ≦ l ≦ 0.1)
[0017]
The raw material powder mixed at a ratio of the composition formula represented by the formula is fired together with sodium carbonate or boron oxide in a reducing atmosphere at 1000 to 1400 ° C., and then pulverized to prepare a slurry as a raw material. Or M²⁺A compound comprising^{* 2 +}  A compound containing³⁺A compound containing⁴⁺A compound containing²⁺A compound comprising Ln³⁺Are mixed at a predetermined ratio (so as to be a compound represented by the composition formula (1) or (2)) to prepare a slurry.
These slurries are adjusted so that the slurry concentration is 10 wt% to 60 wt% and the pH of the solution is 2.0 to 12.0. NaOH, NH₄  OH, HCl, HNO₃  , H₃  PO₄  , NaF, H in solution⁺  , OH⁻  Those capable of adjusting the effective ion concentration can be used.
[0018]
Hydrothermal synthesis is performed in a high-temperature high-pressure chemical reaction vessel such as an autoclave at a temperature of 100 ° C. to 500 ° C. and 500 kg / cm 2.²  The reaction can be carried out at a pressure of up to 1 to 48 hours. The obtained product is washed, filtered, and dried at 80 to 100 ° C. to obtain the above-mentioned fine particles or extremely fine particles having high crystallinity and a high luminance and long persistence hydroxide.
[0019]
BEST MODE FOR CARRYING OUT THE INVENTION
The high-brightness long-lasting hydroxide luminous body of the present invention comprises a hydroxide SrAl₃  O₅Eu of fine particles having an orthorhombic structure of (OH) 2 or having a low crystallinity having the orthorhombic structure²⁺It has excellent water resistance, exhibits high luminance and long persistence even in fine particles or fine particles having low crystallinity, and exhibits an electron beam, ultraviolet light in the range of 220 to 450 nm, visible light, or after excitation by a plurality thereof. It shows thermoluminescence (fluorescence) when the phosphor is heated to or above room temperature.
[0020]
More specifically, the base constituent component of the phosphorescent body has a composition formula represented by the above formula (1) or (2), and the alkaline earth metal element M (particularly, M = Sr is the best).^*  When manganese or zinc is replaced by, the afterglow characteristics are reduced, but the emission luminance can be improved. M^*  The substitution amount n (molar value) should be in the range of 0 ≦ n ≦ 0.2, preferably 0 ≦ n ≦ 0.05, which satisfies the desired condition, but exceeds 0.2. When the substitution is performed, the effect of improving not only the afterglow property but also the luminance is reduced.
[0021]
In addition, Eu contained in the high-luminance long afterglow hydroxide phosphor is included.²⁺The value of m that determines the composition of is preferably 0.0001 ≦ m ≦ 0.1, and more preferably 0.001 ≦ m ≦ 0.01. When m is less than 0.0001, the ion serving as the emission center It is confirmed that the amount is small and sufficient light emission luminance cannot be obtained. On the other hand, when m exceeds 0.1, concentration quenching occurs due to the interaction between the emission center ions, and a by-product of a compound other than the intended one is generated, so that the luminance of the obtained phosphor powder is remarkably reduced.
Eu²⁺With Dy as an activator³⁺And Y³⁺When a rare earth element Ln such as is used, the value of l is preferably 0.0001 ≦ l ≦ 0.1, preferably 0.001 ≦ l ≦ 0.03. In particular, for example, Eu²⁺And Dy³⁺And Y³⁺When three or more rare earth elements are used in common as described above, the effect of high luminance and long persistence is great.
[0022]
SiO in the composition formula₂  The value (molar value) of α that determines the silicon content is in the range of 0 <α ≦ 0.5, and it is necessary to take charge balance with the increase of the amount of dissolved Si. Deficiency in certain maternal composition. The formation of this defect structure can contribute to the emission luminance and afterglow characteristics of the phosphor. Therefore, the range of 0.001 ≦ α ≦ 0.25 is preferable. If the value exceeds this range, particularly, 0 <α ≦ 0.5, the afterglow characteristic and the luminance are reduced. In addition, SiO in the composition formula₂  When the amount of is increased, the light emission behavior of the luminous body obviously changes, and the maximum emission wavelength further shifts to the ultraviolet region.
[0023]
When the starting material of the hydrothermal reaction is sintered at a high temperature, the boric acid added as a flux may be partially replaced by a solid solution with the Al element to improve the afterglow property. It does not exceed 001 mol. In addition, even if excess boric acid is present, only the amount of unreacted material increases, and at the time of hydrothermal reaction, this dissolves in the solution, which is related to promotion of grain growth. Therefore, in order to obtain a hydrothermal reaction product of fine particles, a starting material containing excess boric acid is preferable.
[0024]
The high-temperature sintered phosphor is pulverized to 300 μm or less, placed in an aqueous solution, and adjusted so that the slurry concentration is 10 wt% to 60 wt% and the pH of the solution is 2.0 to 12.0. If the slurry concentration is lower than this, the reactivity is poor and the yield is low because the reactant concentration is low. Conversely, if it is higher than this, friction against stirring increases, the reaction becomes insufficient, and the reaction time increases. Further, the pH is particularly preferably 5 to 10. Those synthesized in this range are the most atomized and have good luminance and afterglow. NaOH, NH for pH adjustment₄  OH, HCl, HNO₃  , H₃  PO₄  , NaF, H in other solutions⁺  , OH⁻  Any of acids or alkalis whose effective ion concentration can be adjusted may be used, or a plurality of them may be used in combination. In addition, the result of the hydrothermal reaction without adjusting the pH can synthesize a hydroxide belonging to the orthorhombic structure.
Regarding the obtained hydroxide product, extra Na introduced during pH adjustment was used.⁺  , Cl⁻  , F⁻  It is desirable to wash and filter such ions, but even without washing, the brightness and afterglow characteristics are not significantly affected. In order to prevent aggregation and grain growth of fine orthorhombic crystals, they are preferably dried at 80 to 100 ° C.
[0025]
The high-luminance long afterglow hydroxide phosphor of the present invention is generally synthesized as follows.
Compound containing M element, M^*  A compound containing an element, a compound containing an Al element, a compound containing a Si element or silicon, and a compound containing an Eu element are mixed at a predetermined amount in the composition formula, and the resulting raw material powder is once reduced. After firing at 1000 to 1400 ° C. in an atmosphere, it is pulverized to 300 μm or less to obtain a raw material for hydrothermal synthesis.
Next, the pulverized phosphor powder is placed in an aqueous solution, the slurry concentration is adjusted to 10 wt% to 60 wt%, and the pH of the solution is adjusted to 2.0 to 12.0. Hydrothermal synthesis is generally performed using a high-temperature high-pressure chemical reaction vessel (autoclave) at a temperature of 100 ° C to 500 ° C and 500 kg / cm.²  The reaction is carried out at a pressure of up to 1 to 48 hours. This hydrothermal synthesis is performed at the autogenous pressure in the following examples, but is performed at 500 kg / cm by using various means used in normal mass production, for example, compressing and introducing argon gas.²  Or more (for example, 2000 kg / cm²  ) To accelerate the reaction and shorten the reaction time. The product obtained is washed, filtered and dried at 80-100 ° C. to obtain the desired phosphor. This luminous body can be used as a single phase, a mixed phase including the same, and the like.
[0026]
The surface of the high-brightness long-lasting hydroxide phosphor of the present invention can be further modified by the above-mentioned hydrothermal synthesis. For example, as a stability in a solution and a workability required for mixing with an ink or a paint, dispersibility in an organic solvent can be improved by organically compounding a hydroxide phosphor.
Further, the average particle diameter of the luminous body obtained in Examples of the present invention is about 7.6 to 9.3 μm, which can achieve 10 μm or less required for ink and the like.
[0027]
In various performance measurements on the obtained hydroxide phosphor powder, a mixture of phosphor and polyester resin in a ratio of 1: 2 (weight ratio) was molded into a sheet or the like, dried, and dried. And 24 hours after the light was cut off, the sample was irradiated with a 15 W white fluorescent lamp at a distance of 100 mm for 30 minutes, and the time-dependent change of the light emission intensity was measured in a dark room.
[0028]
【Example】
Hereinafter, the present invention will be described in more detail with reference to Examples.
[Example 1]
Sr_0.982  Eu_0.005  Dy_0.008  Y_0.005  Al_2.970  Si_0.022  O₅  In order to obtain a hydroxide phosphor of (OH), the same chemical composition (Sr_0.982  Eu_0.005  Dy_0.008  Y_0.005  ) O · 1.5 (Al_1.98Si_0.015  O₃  ) Is placed in 200 ml of distilled water, diluted nitric acid is added, the pH of the slurry is adjusted to 6.0, and then a high-temperature high-pressure chemical reaction vessel (autoclave) is used. ) At 150 ° C. for 2 hours, autogenous pressure of 8.6 kg / cm²  Was subjected to a hydrothermal reaction. The obtained product was washed, filtered and dried at 80 ° C.
[0029]
The phase of the dried powder was identified by powder X-ray diffraction. FIG. 1 shows a pattern of powder X-ray diffraction by CuKα radiation. Table 1 shows lattice spacing values of the hydrothermal product in powder X-ray diffraction. This is SrAl with orthorhombic structure₃  O₅  It has the same form as the OH compound, and as a result of determining the lattice constant, a = 8.518 °, b = 24.670 °, and c = 4.896 °.
[0030]
[Table 1]

[0031]
When the emission spectrum of the sample which was excited by 240 nm ultraviolet rays was measured for the hydroxide phosphor, the peak giving the maximum emission intensity, which was the same as the starting material before hydrothermal treatment, was located near 486 nm, and emitted blue-green light. .
Table 2 shows relative values after hydrothermal treatment when the bulk density, luminous intensity, and BET specific surface area of the phosphor powder before hydrothermal treatment are set to 100. As shown in C of Table 2, it was found that after the hydrothermal treatment, the phosphor was extremely fine, had a bulk density of half or less, and had a BET specific surface area of about 20 times larger than that of the phosphor before the hydrothermal treatment.
[0032]
[Table 2]

[0033]
[Example 2]
Sr_0.982  Eu_0.005  Dy_0.008  Y_0.005  Al₃  O₅In order to obtain a hydroxide phosphor of (OH) 2, the same chemical composition (Sr_0.982  Eu_0.005  Dy_0.008  Y_0.005  Al₂  O₄  ) Having a particle size of 63 μm or less as a starting material, placed in 200 ml of distilled water, adjusting the pH of the slurry to 8.3 by adding dilute hydrochloric acid, and then using a high-temperature high-pressure chemical reaction vessel (autoclave). ) At 200 ° C. for 10 hours, autogenous pressure 11.3 kg / cm²  Was subjected to a hydrothermal reaction. The obtained product was separated into a white product and a yellow particulate product, which were separated, washed, filtered, and dried at 80 ° C.
[0034]
The two powders obtained by the above-mentioned drying were subjected to phase identification by powder X-ray diffraction.
FIG. 2 (b) shows a powder X-ray diffraction pattern of a white product, and FIG. 2 (c) shows a yellow particle product by CuKα radiation. For comparison, the pattern of the powder X-ray diffraction before hydrothermal treatment is shown in FIG. The yellow particulate product is cubic Sr₃  Al₂(OH)₁₂  Belongs to. Then, as shown in FIG. 2 (b), the white ones belong to the orthorhombic structure Sr._0.982  Eu_0.005  Dy_0.008  Y_0.005  Al₃  O₅It was found that (OH) 2 was a fine particle having low crystallinity, and that (hkl) had a peak of (020) and 2θ ranged from 11 to 17 degrees.
[0035]
The white fine particles were subjected to infrared absorption and TG analysis. FIG. 3 shows the results of infrared absorption, and FIG. 4B shows the results of TG analysis. For comparison, the TG analysis result before hydrothermal treatment is shown in FIG. In the infrared absorption shown in FIG. 3, the behavior of the OH group was confirmed. In FIG. 4, dehydration of the hydroxide was observed between 400 ° C. and 500 ° C. in the white fine particle sample.
FIG. 5A shows an SEM photograph of the white fine particle sample, and FIG. 5B shows an SEM photograph of the sample before hydrothermal treatment. As shown in these photographs, the hydroxide phosphor obtained by the hydrothermal synthesis of the present invention is a fine particle that cannot be obtained by a solid-phase reaction, and the average particle size of the aggregate is 7.6 μm. there were.
[0036]
When the change over time in the emission intensity of both particles was measured, Sr belonging to a white orthorhombic structure was obtained._0.982  Eu_0.005  Dy_0.008  Y_0.005  Al₃  O₅The fine particles of (OH) emitted light well, but yellow particles of cubic system (Sr, Eu, Dy, Y)₃  Al₂(OH)₁₂  Showed only weak light emission.
Further, as shown in A of Table 2 above, the relative bulk density, relative luminescence intensity, and relative BET specific surface area after hydrothermal treatment were extremely fine compared to the phosphorescent material before hydrothermal treatment, and the bulk density was 11.5%. And the BET specific surface area is 155.3m²  / G, which is about 300 times larger.
[0037]
Further, FIG. 6A shows an excitation spectrum of white fine particles, and FIG. 6B shows an emission spectrum of the same sample excited by 240 nm ultraviolet rays. For comparison, FIGS. 7A and 7B show an excitation spectrum before hydrothermal treatment and an emission spectrum of the same sample excited by ultraviolet light of 250 nm.
According to these figures, the sample before hydrothermal treatment has a peak at 513 nm giving the maximum emission intensity, whereas the white fine particles after hydrothermal emission has a blue-green emission with a peak giving the maximum emission intensity near 486 nm. You can see that.
[0038]
[Example 3]
Using 50 g of the powdery phosphor of 106 μm or less obtained in Comparative Example 3 described below as a starting material, put it in 200 ml of distilled water, and adjust the temperature to 180 ° C. without adjusting the pH using a high-temperature and high-pressure chemical reaction vessel (autoclave). The hydrothermal reaction was performed at the autogenous pressure for 5 hours. The product obtained was washed, filtered and dried at 80 ° C.
[0039]
The dried powder was subjected to phase identification by powder X-ray diffraction. FIG. 8 shows a pattern of powder X-ray diffraction by CuKα ray, and Table 3 shows a distance between lattice planes. This also had an orthorhombic structure, and the lattice constants were a = 8.512 °, b = 24.788 °, and c = 4.893 °.
This hydroxide phosphor was measured for the emission spectrum of a sample excited by 240 nm ultraviolet light, and the peak giving the maximum luminescence intensity was a blue-green luminous phosphor located near 485 nm.
Further, as shown in B of Table 2, the phosphor was extremely fine and had a bulk density of one third or less as compared with the phosphorescent material before hydrothermal treatment.
[0040]
[Table 3]

[0041]
[Example 4] Water resistance test
Regarding the water resistance, 10 g of the phosphor powder pulverized to 30 μm or less in each of Examples and Comparative Examples was weighed, placed in a beaker having a capacity of 300 ml together with 200 ml of distilled water, and stirred for 2 hours with a magnetic stirrer at 40 ° C. At 80 ° C. for 100 hours. The luminance before and after the warm water treatment was measured, and the rate of decrease in luminance was determined. With respect to the results, Table 4 shows the relative luminance after the hot water treatment when the luminance before the hot water treatment is set to 100. It was found that the brightness after the warm water treatment was almost unchanged, stable in an aqueous solution, and excellent in water resistance.
[0042]
[Table 4]

[0043]
[Comparative Example 1]
(Sr_0.982  Eu_0.005  Dy_0.008  Y_0.005  ) O · 1.5 (Al_1.98Si_0.015  O₃  )) To obtain a phosphor having the chemical composition of₃  BO₃  And the following amounts of the raw material powders were weighed. Next, an appropriate amount of distilled water was added, and the mixture was wet-mixed in a ball mill for 20 hours.
SrCO₃                              72.480 g
Al₂  O₃                              75.699 g
SiO₂                                  0.676g
Eu₂  O₃                                0.440g
Dy₂  O₃                                  0.746g
Y₂  O₃                                      0.282g
H₃  BO₃                                7.515 g
[0044]
The mixed powder obtained by drying it at 100 ° C. was 1000 kg / cm²  This was molded using an 80 mm square mold molding machine with a load of, placed in an alumina crucible, fired at 1300 ° C. for 2 hours in an argon gas containing 3% hydrogen using an electric furnace, cooled, and then cooled with alumina. The sample was finely ground in a mortar, molded again using a mold molding machine, and fired again under the same conditions as the first time to obtain a phosphorescent sample.
The peak giving the maximum emission intensity of this sample excited by 360-nm ultraviolet light was located near 490 nm, and it was found that the sample was a blue-green luminous phosphor.
The obtained blue-green luminous phosphor was pulverized to 300 μm or less to obtain a raw material for a hydrothermal reaction. The properties and the like of the light storage of Comparative Example 1 have already been described in comparison with Example 1 and the like.
[0045]
[Comparative Example 2]
Sr_0.982  Eu_0.005  Dy_0.008  Y_0.005  Al₂  O₄  A phosphorescent body having the chemical composition of was prepared as follows. H as flux₃  BO₃  Was added, and the following amounts of the raw material powders were weighed, and an appropriate amount of distilled water was added thereto, and the mixture was wet-mixed with a ball mill for 20 hours.
SrCO₃                              72.480 g
Al₂  O₃                              50.799g
Eu₂  O₃                                0.440g
Dy₂  O₃                                  0.746g
Y₂  O₃                                      0.282g
H₃  BO₃                                  3.704g
[0046]
The mixed powder obtained by drying it at 100 ° C. was 1000 kg / cm²  This was placed in an alumina crucible, baked in an argon gas containing 3% hydrogen at 1400 ° C. for 2 hours using an electric furnace, and cooled. Obtained by fine grinding in a mortar.
FIG. 2 (a) shows an XRD pattern as a result of a pulverized X-ray diffraction of Comparative Example 2 thus synthesized. This belongs to a monoclinic stuffed tridymite structure.
The peak giving the maximum emission intensity of the sample excited by 360-nm ultraviolet light was located near 513 nm, and it was found that the sample was a yellow-green luminescent phosphor.
The obtained yellow-green luminous phosphor was pulverized to 63 μm or less to obtain a raw material for a hydrothermal reaction. The properties and the like of the light storage body of Comparative Example 2 have already been described in comparison with the examples.
[0047]
[Comparative Example 3]
(Sr_0.972  Mn_0.01Eu_0.005  Dy_0.008  Y_0.005  ) O · 1.2 (Al_1.92Si_0.06O₃  A phosphorescent body having the chemical composition of (1) was prepared as follows. H as flux₃  BO₃  , And the following amounts of the raw material powders were weighed, and an appropriate amount of distilled water was added thereto and wet-mixed for 20 hours in a ball mill.
SrCO₃                              71.747 g
MnO₂                    0.435g
Al₂  O₃                              58.730 g
SiO₂                                  2.163g
Eu₂  O₃                                0.440g
Dy₂  O₃                                  0.746g
Y₂  O₃                                      0.282g
H₃  BO₃                                6.630 g
[0048]
The mixed powder obtained by drying it at 100 ° C. was 1000 kg / cm²  With a load of 80 mm, a mold was formed using a 80 mm square mold molding machine, and this was placed in an alumina crucible, fired at 1280 ° C. for 3 hours in an argon gas containing 3% hydrogen using an electric furnace, cooled, and then cooled. The mixture was finely ground in a mortar, molded again using a mold molding machine, and fired again under the same conditions as the first time to obtain a phosphorescent sample of Comparative Example 3.
The peak giving the maximum emission intensity of the sample excited by the 240 nm ultraviolet ray was located at around 490 nm, which was found to be a blue-green luminous phosphor.
The obtained blue-green light-emitting phosphor was pulverized to 106 μm or less to obtain a raw material for a hydrothermal reaction. The properties and the like of the light storage body of Comparative Example 3 have already been described in comparison with the examples.
[0049]
【The invention's effect】
According to the high-brightness long afterglow hydroxide phosphor of the present invention described in detail above, the specific surface area is about 10 to 300 times larger than the oxide phosphor obtained by the solid-state reaction of high-temperature sintering, especially The water resistance is remarkably improved, the stability in an aqueous solution is excellent, and it is highly practical in application fields such as inks and paints.
[Brief description of the drawings]
FIG. 1 is a diagram showing an X-ray diffraction pattern of a phosphor powder according to Example 1 of the present invention.
FIG. 2 is a diagram showing an X-ray diffraction pattern of a phosphor powder according to Example 2 of the present invention, wherein (a) is a white product before hydrothermal treatment, (b) is a white product after hydrothermal treatment, and (c) is FIG. 2 is a diagram showing a powder X-ray diffraction pattern of a yellow particulate product after hydrothermal treatment.
FIG. 3 is an infrared absorption diagram of a white sample of Example 2 of the present invention.
4A is a thermobalance analysis diagram of a white sample of Example 2 of the present invention, and FIG. 4B is a thermobalance analysis diagram of a sample before hydrothermal synthesis (Comparative Example 2) of Example 2. FIG.
FIG. 5 (a) is a scanning electron micrograph as a substitute for a drawing of a white sample microparticle of Example 2 of the present invention, and FIG. 5 (b) is a sample of the sample before hydrothermal heating.
FIG. 6A is an excitation wavelength diagram of a white sample of Example 2 of the present invention, and FIG. 6B is an emission wavelength diagram thereof.
7A is an excitation wavelength diagram of a sample before hydrothermal synthesis according to Example 2 of the present invention, and FIG. 7B is an emission wavelength diagram thereof.
FIG. 8 is a diagram showing a powder X-ray diffraction pattern of a sample of Example 3 of the present invention.

Claims (4)

The composition formula is

(However, □ in the formula is a composition defect, M is at least one kind of alkaline earth metal element selected from magnesium, calcium, strontium and barium, M ^* is at least one kind of divalent substance selected from manganese and zinc.) The metal element and Ln represent one or more kinds of rare earth elements other than Eu, and n, m, l, and α are numerical values satisfying the following ranges, respectively.
0 ≦ n ≦ 0.2
0 <α <0.5
0.0001 ≦ m ≦ 0.1
0.0001 ≦ l ≦ 0.1)
From a single phase having an orthorhombic structure of a hydroxide SrAl ₃ O ₅ (OH) by hydrothermal synthesis represented by the following formula, a mixed phase containing the same, or a phase having a low crystallinity in the orthorhombic structure. An orthorhombic hydroxide phosphor that activates Eu ²⁺ . The composition formula is
_{^{(M 1-n-m-}} l M * nEu m Ln l) Al 3 O 5 (OH)
(Where M is one or more alkaline earth metal elements selected from magnesium, calcium, strontium and barium, M ^* is one or more divalent metal elements selected from manganese and zinc, and Ln is Represents one or more rare earth elements other than Eu, and n, m, and l are numerical values that satisfy the following ranges.
0 ≦ n ≦ 0.2
0.0001 ≦ m ≦ 0.1
0.0001 ≦ l ≦ 0.1)
From a single phase having an orthorhombic structure of a hydroxide SrAl ₃ O ₅ (OH) by hydrothermal synthesis represented by the following formula, a mixed phase containing the same, or a phase having a low crystallinity in the orthorhombic structure. A hydroxide phosphor which activates Eu ²⁺ . A method for producing an orthorhombic hydroxide phosphor according to claim 1,
As a starting material, a compound containing M, a compound containing M ^* , a compound containing Al, a compound containing Si or silicon, a compound containing Eu ²⁺ and a compound containing Ln in the composition formula are used, and hydrothermal synthesis is performed on them. Producing a high-brightness, long-lasting Eu ²⁺ -activated orthorhombic hydroxide phosphor having excellent water resistance obtained through a hydrothermal reaction. Manufacturing method. A method for producing a hydroxide phosphor according to claim 2,
As a starting material, a compound containing M, a compound containing M ^* , a compound containing Al, a compound containing Eu ^2+, and a compound containing Ln in the composition formula are used. A method for producing an orthorhombic hydroxide phosphor having a high luminance and a long afterglow Eu ²⁺ activated phosphor having excellent water resistance.

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