JP3559210B2 - Heat-resistant, water-resistant, high-brightness, long-lasting yellow-green luminescent color phosphor and a method for producing the same - Google Patents

Description

【００２４】
１ｗｔ％ふっ化リチウムを添加し、１２５０℃で２時間の焼成を行った試料は、単一相のＳｒＡｌ_２ Ｏ_４ からなり、化学分析の結果、０．０５８モルのフッ素を含むことがわかった。これに対し、５ｗｔ％のふっ化リチウムを添加し、１２５０℃で２時間の焼成を行った後の試料には、ＳｒＦ_２ が混在した。一方で、さらに再焼成を行うことにより、ＳｒＡｌ_２ Ｏ_４ と同じピークをもつ単一相が得られた。
以上の結果より、添加されたふっ化リチウムのＦ⁻ が、蓄光体格子のＯ^２−と一部置き換わること、Ｏ^２−キラセンターの濃度が減少する一方、一部の格子が歪み、輝度向上が図れたものと考えられる。
【００２５】
（３）電荷バランス効果；
硼素とフッ素とを同時添加することにより、ＳｒＯ・ｒＡｌ_２ Ｏ_３ ：Ｅｕ，Ｄｙ蓄光体は、より活性化した母体、より活性化されたＥｕ^２＋発光センターとＬｎ^３＋共賦活剤との均一分散が実現できる。その結果、有効なエネルギー移動がなされ、高輝度発光性能に寄与する。反応的に考えると、フッ素、硼素の存在下では、ＳｒＣＯ_３ →ＳｒＯ＋ＣＯ_２ ↑の反応がより促され、生成したＳｒＯは反応性に富むことから、Ａｌ_２ Ｏ_３ との反応を短時間に終了することができる。更には、フッ素の存在がＥｕ^２＋の安定に寄与している。
【００２６】
（４）酸素欠損の安定化効果；
酸素イオンの欠損によって生ずる格子不安定が水酸化物イオンではなく、フッ素イオンによって捕らわれるために、蓄光体粒子の溶解を防ぎ、耐熱・耐水性が向上することに寄与しているものと考えられる。
【００２７】
（５）発光挙動；
１）．出発原料に対し１ｗｔ％〜５ｗｔ％のふっ化リチウムを添加したものは、全て最大励起波長が２０５ｎｍ〜２０８ｎｍで、最大発光波長は５１２ｎｍ〜５１７ｎｍにある。また、ふっ化リチウム添加量の増加に伴い、半値幅が次第に７５ｎｍから８０ｎｍと大きくなり、結晶性の低下とともに初期発光輝度が低くなることが観察された。
焼成工程中でのフッ素の損失（ＡｌＦ_３ ↑、ＨＦ↑）もしくは、副生成物としてのＳｒＦ_２ 等の生成により、蓄光体の組成が微小にずれる（非化学量論比）と考えられるのに加えて、格子に取り込まれたフッ素、硼素の影響により、結晶性は向上するが、特に４％以上の添加では輝度が低下する。
【００２８】
２）．賦活剤及び共賦活剤を添加しないＳｒＡｌ_２ Ｏ_４ ：Ｆにおいて、長発光及び残光が観察された。
ＳｒＣＯ_３ とＡｌ_２ Ｏ_３ を等モルの割合で秤量し、ふっ化リチウムを０％、１ｗｔ％、３ｗｔ％、５ｗｔ％と添加した混合粉末をφ２０に成型し、１２５０℃、２時間、３％Ｈ_２ 含有アルゴンガス中で焼成し、さらに、ふっ化リチウム１ｗｔ％と硼酸１ｗｔ％とを同時添加した試料（ＳＡＢＦ）についても同条件で焼成した結果、ふっ化リチウム無添加の試料は、焼成後の体積変化が殆どなく、紫外線ランプ照射下においても発光が観察されなかった。これに対し、ふっ化リチウムを加えた他の試料は、かなり収縮して緻密な組織を呈し、紫外線励起下にて青緑の蛍光を示すと共に、励起停止後に残光も観察された。特に、ＳＡＢＦ試料は発光強度が大きく、長残光性であった。
このような高効率発光組成物にＥｕ^２＋，Ｄｙ^３＋などを賦活すると、優れた蓄光特性を発揮する。
【００２９】
本発明では、フッ素と硼素の同時添加で、結晶成長が著しく、微粉でも高輝度・長残光性が安定に維持できる蓄光体が得られる点に特徴がある。従来の蓄光体の発光輝度と残光性は、粉末の粒径に影響を受け、粒子が細かくなると発光輝度と残光性が顕著に悪くなる。たとえば、平均粒径が１０μｍと３０μｍの蓄光体を比較して、励起後３分の輝度は６０：１００の割合になるが、本発明の試料では９５：１００と極めて粒径の影響が少ない。
更に、本発明では、フッ素もしくはフッ素と硼素の同時添加により、従来の硼酸のみ添加した焼結体に比べて、焼結体硬度が低いことより、粉砕工程が容易で、生産性が高くなるなどの特徴もある。
【００３０】
また、より低温での焼成が可能であり、特に、蓄光粉末と樹脂とを混合して成型する際に金属容器などからの汚染が小さく、輝度の劣化を防止できる大きな特徴がある。
更に、低温焼結が可能であることから、現在のバッチ式炉からトンネル式連続炉が使用できるようになり、加えて、耐熱ステンレス材が炉材として使用可能となることなどから、設備費が安価な量産化のためのシステム化を図るのが容易になる。
【００３１】
【実施例】
以下に実施例を示し、更に詳しく本発明について説明するが、それに先立ち、以下の実施例における残光輝度測定、耐熱性試験、耐水性試験の方法について説明する。
【００３２】
先ず、残光輝度測定の方法は次の通りである。
実施例または比較例の蓄光体の粉末を、ポリエステル樹脂等と共に均一に混合し、［蓄光体：ポリエステル樹脂］が重量比で１：２の比率として、厚さ２．５ｍｍのシート状に成型、乾燥し、これを発光強度の経時変化の測定試料とする。測定は、光遮断後２４時間暗室に置かれた測定試料に、１５Ｗ白色蛍光灯を用いて、１００ｍｍの垂直距離から１５分間試料を照射した後、その発光輝度の経時変化を測定する。表２及び表３にその測定結果を示す。
【００３３】
耐熱性試験の方法は次の通りである。
３００μｍ以下の大きさをもつ蓄光粉末を５ｇ秤量し、アルミナ坩堝に入れて電気炉中８００℃及び９００℃で１時間大気中酸化焼成を行った試料を用い、発光輝度を測定し、焼成前の残光輝度に対する輝度維持率を求める。表４にその測定結果を示す。
なお、本発明で得られた蓄光体については、たとえ大気中９００℃で加熱しても、尚７０％以上の輝度維持率を示した。加えて、１０ｍｍ×１０ｍｍ×２０ｍｍの大きさに成型した蓄光体を１２００℃で１８０分間大気中で酸化焼成を行ったが、この場合にも約４３％の維持率を示した。
【００３４】
耐水性試験の方法は次の通りである。
３００ｍｌビーカーに純水を２００ｍｌ入れ、３００μアンダーの蓄光体粉末を１０ｇ加え、２４時間含浸させた後、乾燥してその残光輝度を測定し、水処理前の残光輝度に対する輝度維持率を求める。表５にその測定結果を示す。
【００３５】
［参考例１］
Ｓｒ_{０．９８７} Ｅｕ_{０．００５} Ｄｙ_{０．００８} Ａｌ_２ Ｏ_４ ：Ｂ_{０．０４１} Ｆ_{０．０５８} の化学組成式の量比になるように、出発原料粉末（純度９９．９％）としての、ＳｒＣＯ_３ ，Ａｌ_２ Ｏ_３ ，Ｅｕ_２ Ｏ_３ ，Ｄｙ_２ Ｏ_３ ，Ｈ_３ ＢＯ_３ ，ＬｉＦを、それぞれ、
ＳｒＣＯ_３ ＝０．９８７×１４７．６３＝１４５．７１ｇ
Ａｌ_２ Ｏ_３ ＝１×１０１．９６＝１０１．９６ｇ
Ｅｕ_２ Ｏ_３ ＝０．００５×１／２×３５１．９３＝０．８８ｇ
Ｄｙ_２ Ｏ_３ ＝０．００８×１／２×３７３．０００＝１．４９ｇ
Ｈ_３ ＢＯ_３ ＝０．０４１×６１．８３＝２．５４ｇ
ＬｉＦ＝０．０９８×２５．９４＝２．５４ｇ
ずつ正確に秤量し、ボールミルにて２４時間、純水による湿式混合を行った。
【００３６】
次いで、１４０℃で乾燥し、混合粉末を得た。この混合粉末をアルミナ性耐熱容器に詰め、ステンレス製炉心管の電気炉を用いて、３％の水素含有アルゴンガス中、１１００℃で１時間焼成した。冷却後、回収した試料を粉砕し、本発明の蓄光体粉末を得た。
化学分析の結果、フッ素含有量は０．０５８モルであった。粉末Ｘ線回折法により、単一相の単斜晶系で指数付けする事が出来た。また、ＳＥＭ観察により、本蓄光体は低温・短時間の焼成工程にもかかわらず、高い結晶性を示す様子が観察された。
【００３７】
図４に、２６０ｎｍの紫外線で励起した時の発光スペクトルを示す。これは最大発光波長が５１２ｎｍ付近にある黄緑発光色蓄光体である。
発光強度の時間変化を測定するために、３００μｍ以下の粒径をもつ蓄光体粉末１．２５ｇとポリエステル樹脂２．５ｇとを秤量し、均一に混合した後、厚さ２．５ｍｍのシートに成型、乾燥したものを作製し、前述の方法により、励起停止後の発光強度の変化を測定した。表２の実施例１の欄にその結果を示す。また、耐熱性試験の結果を表４に示す。
【００３８】
［実施例または参考例２〜１８］
実施例または参考例２〜１８の具体的な化学組成式と焼成条件を表２に示す。これらの実施例については、実施例１と同様に、必要な出発原料粉末ＳｒＣＯ_３ ，ＣａＣＯ_３ ，Ａｌ_２ Ｏ_３ ，Ｅｕ_２ Ｏ_３ ，Ｄｙ_２ Ｏ_３ ，Ｙ_２ Ｏ_３ ，Ｓｍ_２ Ｏ_３ ，Ｔｍ_２ Ｏ_３ ，Ｈ_３ ＢＯ_３ ，ＬｉＦ，ＭｇＯ，ＭｎＯ，ＺｎＯ，Ｂｉ_２ Ｏ_３ の所定量を秤量し、ボールミルにて２４時間純水湿式混合を行った後、１４０℃で乾燥して、混合粉末を得た。これをカーボンるつぼに入れ、アルミナ炉材の電気炉を用いて、３％水素含有窒素ガス中で焼成した。それぞれの試料は冷却後に粉砕し、３００μｍ以下の大きさをもつ粒子をふるいで分級し、本発明の蓄光体を得た。
【００３９】
これらの実施例、参考例及び以下に述べる比較例の発光輝度の時間変化（残光輝度）を表２及び表３に、耐熱・耐水性試験における輝度維持率を表４及び表５にまとめた。
大気中、８００℃で１時間の加熱処理による耐熱性試験では、表４の耐熱性試験結果に示すように、本発明の各実施例の蓄光体は高輝度を維持し、励起停止３分後では、耐熱処理前の８３％以上の維持率を示した。これに対して、比較例として用いた全ての試料は白くなり、輝度維持率は１％以下になった。
また、耐水性については、本発明の蓄光体は８５％以上の維持率を示し、比較例の試料はその維持率が６．２％程度となった。
【００４０】
【表２】

【００４１】
【表３】

【００４２】
【表４】

【００４３】
【表５】

【００４４】
従来のアルミン酸塩蓄光体においては、硼素が実質的になくてはならない添加組成であるのに対して、参考例１７，１８においては、フッ素のみ含有しても高い発光性能を有している。
【００４５】
［比較例１］
Ｓｒ_{０．９８７} Ｅｕ_{０．００５} Ｄｙ_{０．００８} Ａｌ_２ Ｏ_４ ：Ｂ_{０．０４１} の化学組成を有するフッ素を含有しない比較例１の蓄光体を、次のようにして得た。
純度９９．９％の下記出発原料粉末をそれぞれ秤量し、参考例１で示した方法により混合し、表２に示すように、１４００℃で２時間の焼成条件により作製した。
ＳｒＣＯ_３ １４５．７１ｇ
Ａｌ_２ Ｏ_３ １０１．９６ｇ
Ｅｕ_２ Ｏ_３ ０．８８ｇ
Ｄｙ_２ Ｏ_３ １．４９ｇ
Ｈ_３ ＢＯ_３ ２．５４ｇ
【００４６】
得られた試料の蓄光特性及び耐水・耐熱性試験の結果は、表２〜表５中に示している。この比較例１の試料は、表３に示すように、参考例４と比較して、輝度・残光性とも低く、さらに、表４に示すように、大気中８００℃にて加熱すると白くなり、その発光性能を失った。また、表５に示すように、２４時間水処理した耐水性試験では、励起停止後の残光輝度は低く、その維持率は６．２％程度であった。
【００４７】
［比較例２］
Ｓｒ_{０．９７５} Ｅｕ_０．０１Ｄｙ_{０．０１５} Ａｌ_２ Ｏ_４ の化学組成を有するフッ素及び硼素を添加しない比較例２の蓄光体を、参考例１と同じ方法を用い、表２に示すように、１５００℃で２時間焼成して作製した。この比較例２の蓄光体は、表２に示すように著しく発光輝度や残光性が低下した。
【００４８】
【発明の効果】
以上に詳述した本発明によれば、耐水・耐熱性に優れ、極めて高い初期輝度と長い残光特性を持つフッ素含有黄緑発光色蓄光体を得ることができる。また、従来のＳｒＡｌ_２ Ｏ_４ ：Ｅｕ，Ｄｙよりも、フッ素と硼素の含有によって、粉砕が容易で粉末製品が得やすく、金属粉の汚染を防止するのにも役立つ。
さらに、本発明の製造方法は、高輝度を維持し、微粉状の蓄光体を作製するのに好適なプロセスを有し、従来のように、高温・長時間の焼成条件を、より低温・短時間とすることが可能で、エネルギー節約、生産性向上などの量産化のための好条件を有するものである。
【図面の簡単な説明】
【図１】フッ素と硼素が無添加の場合の焼成蓄光体試料の破断面の図面代用走査型電子顕微鏡写真である。
【図２】フッ素のみを添加した場合の焼成蓄光体試料の破断面の図面代用走査型電子顕微鏡写真である。
【図３】フッ素と硼素を共に添加した場合の焼成蓄光体試料の破断面の図面代用走査型電子顕微鏡写真である。
【図４】参考例１で得られた蓄光体の発光スペクトル（励起波長：２６０ｎｍ，発光波長：５１２ｎｍ）を示す図である。[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a strontium aluminate phosphor of high luminance and long afterglow yellow-green emission color excellent in heat resistance and water resistance containing fluorine and a method for producing the same, more specifically, at a low temperature of 1000 ° C. An object of the present invention is to provide a strontium aluminate phosphor that is calcinable, has excellent productivity, has high initial luminance and afterglow luminance, and is chemically stable.
[0002]
[Prior art]
The phosphorescent body is excited by external energy such as electron beam, X-ray, ultraviolet ray, sunlight, fluorescent light and the like, and emits light for a long time after the excitation is stopped. Excitation and emission can be repeated semipermanently.
Conventionally, as a sulfide-based phosphor, blue light-emitting (Ca, Sr) S: Bi, yellow-green light-emitting ZnS: Cu, and red light-emitting (Zn, Cd) S: Cu are known. These have low afterglow luminance, have the problem that they are decomposed by ultraviolet rays under high-temperature and high-humidity conditions and become black, and the afterglow luminance is significantly deteriorated. Use was limited.
[0003]
In recent years, aluminate phosphors that are chemically more stable and have a long afterglow time that can be visually confirmed in the dark place (Japanese Patent No. 2543825, US Pat. No. 5,376,303, and JP-A-8-151574). No.), silicate phosphors (JP-A-9-194833), aluminum silicate phosphors (JP-A-9-238966), and the like.
[0004]
As the aluminate phosphor, SrAl emitting yellow-green light was used.₂  O₄  : Eu, Dy emits blue-green Sr₄  Al₁₄O₂₅: Eu, Dy, SrAl₄  O₇  : Compared to Eu, Dy, etc., it is pointed out that although the emission luminance in the initial stage (for example, one minute after excitation) is higher, the afterglow and weather resistance, particularly water resistance, are inferior.
Further, Japanese Patent Application Laid-Open No. 8-151574 discloses that yellow phosphorescent SrAl is contained by adding phosphorus.₂  O₄  : The heat and water resistance of the Eu and Dy phosphors was improved, and after calcination at 600 ° C. for 30 minutes, the persistence of afterglow luminance was 76.6% before the calcination, and stirring in water for 72 hours was performed. Over time, it reports 49.1%.
[0005]
[Problems to be solved by the invention]
The present inventor has proposed that₂  O₄  : Results of intensive studies on components that are excellent in heat resistance and water resistance and can achieve high luminance and long afterglow by stabilizing the crystal structure of Eu, Dy phosphor, crystal growth, firing at low temperature, controlling defects, etc. By containing fluorine, in particular, by simultaneously containing boron and fluorine, the emission luminance one minute after excitation is stopped is up to about 1.7 times, and the emission luminance one hour later is up to 3.1 times. It has been found that a phosphorescent body having improved heat resistance and water resistance can be mass-produced at a lower firing temperature at a lower cost.
[0006]
The present invention is based on this finding, and its basic problem is to solve the above-mentioned yellow-green luminescent SrAl having a high initial emission luminance.₂  O₄  : To provide a yellow-green light-emitting phosphor having improved initial light emission luminance and afterglow time more than the Eu and Dy phosphors.
Another object of the present invention is to provide a yellow-green luminescent color phosphor having high heat resistance, which does not deteriorate its luminous properties even when fired in the air.
Another problem to be solved by the present invention is to provide a yellow-green luminous phosphor that can maintain its luminous properties for a long time when using an aqueous phosphorescent ink or an applied product such as an automotive phosphorescent paint outdoors or underwater. To provide.
[0007]
Further, another problem to be solved by the present invention is to enable firing at a low temperature and in a short time, thereby enabling a batch type furnace to be changed to a carrier type tunnel furnace and facilitating mass continuous production. It is an object of the present invention to provide a green light emitting phosphor and a method of manufacturing the same.
Another object of the present invention is to make it possible to use a heat-resistant stainless steel as a furnace material by enabling firing at a low temperature, thereby achieving a system for mass production at a low equipment cost. And a method for producing the same.
[0008]
[Means for Solving the Problems]
The yellow-green luminescent color phosphor of the present invention for solving the above-mentioned problems has a composition formula of
(Sr_1-nmqq E '_nEu_m Ln_k Y_q ) Al₂ O₄ : B_x , F_y , Or (Sr_1-nmqq E '_nEu_m Ln_k Y_q ) O ・ rAl₂ O₃ : B_x , F_y
(However, 0 ≦ n ≦ 0.1
0 <m ≦ 0.05
0 <k ≦ 0.1
0 <q ≦ 0.05
1 ≦ r ≦ 1.50
0 ≦ x ≦ 0.1
0 <y ≦ 0.1
Where E ′ is at least one metal element selected from the group consisting of Mn, Zn, Bi, Ca, Mg, and Ba, and Ln is Ce, Pr, Gd, Tb, Dy, Ho, Er, One or more lanthanoid elements selected from the group consisting of Tm, Yb, and Lu)
Fluorine-containing strontium aluminate represented by and indexed in monoclinic systemMain componentIt is assumed that.
[0009]
Further, a method for producing a yellow-green luminescent color phosphor according to the present invention for solving the above-mentioned problems, comprises a simple powder containing the elements Sr, Al, Eu, Y, E ', Ln and B in any one of the above composition formulas. Alternatively, a compound powder or solution is weighed so as to have a composition ratio of the above composition formula, and a compound powder or solution containing the F element is calcined and weighed so as to have a composition ratio of the above composition formula as a starting material. Then, after mixing them, the mixed powder obtained by drying and pulverizing is put into a heat-resistant container, molded, or fired at 1000 ° C. to 1500 ° C. in a reducing atmosphere for 30 minutes to 2 hours in a reducing atmosphere. And characterized in that the cooled fired product is pulverized into a powder.
[0010]
According to the yellow-green luminescent color phosphor having the above configuration and the method of manufacturing the same, the conventional SrAl₂  O₄  : Has higher initial light emission luminance and afterglow time than the Eu and Dy phosphors, and has high heat resistance such that the phosphorescent property does not decrease even when fired in air (500 ° C. to 900 ° C.). When an applied product such as a water-based luminous ink or a luminous paint for automobiles is used outdoors or underwater, a yellow-green luminous phosphor that can maintain the luminous characteristics for a long time can be obtained.
Moreover, the yellow-green luminescent SrO.rAl₂  O₃  : Since Eu and Dy phosphors can be fired at a low temperature and in a short time (for example, at 1150 ° C. for 30 minutes), a batch type furnace can be changed to a carrier type tunnel furnace and mass continuous production is easy. At the same time, as in products such as luminous glass beads and luminous ceramic tiles that require high heat resistance (oxidative calcination resistance), luminous characteristics do not decrease even when baked in air (500 ° C to 900 ° C). In addition, when an applied product such as a water-based luminous ink or a luminous paint for automobiles is used outdoors or underwater, the luminous characteristics can be maintained for a long time.
[0011]
BEST MODE FOR CARRYING OUT THE INVENTION
The heat-resistant, water-resistant, high-brightness, long afterglow yellow-green luminescent color phosphor according to the present invention is represented by the above composition formula and is indexed by a monoclinic system and is mainly composed of a fluorine-containing strontium aluminate. The yellow-green luminous color phosphor can be manufactured as follows.
That is, a simple powder, a compound powder or a solution containing the elements Sr, Al, Eu, Y, E ', Ln, and B in the above composition formula having a high purity (purity of 99% or more) has a quantitative ratio of the above composition formula. The starting material is weighed in such a manner that the compound powder or solution containing the element F is baked and weighed so as to have the quantitative ratio of the above composition formula, and after thoroughly mixing, drying and pulverizing, The mixed powder thus obtained is put into a heat-resistant container such as a ceramic, and molded or fired in a reducing atmosphere at 1000 ° C. to 1500 ° C. for 30 minutes to 2 hours. By pulverizing the phosphor into a yellowish-green light-emitting phosphorescent powder, the target substance is obtained.
[0012]
The phosphors provided by the present invention typically have a maximum emission intensity in the range of 510 to 520 nm, and the conventional fluorine-free SrAl₂  O₄  : Higher initial luminance and longer afterglow time than Eu · Dy. In particular, by containing both boron and fluorine, the effect becomes extremely remarkable.
These effects are₂  Al₆  O₁₁It is also effective for other blue or blue-green luminescent phosphors mainly composed of strontium aluminate. For example, Sr₂  Al₆  O₁₁In the yellow-green light-emitting phosphor (without the presence of boric acid), the sintering temperature is lowered by containing fluorine, and the crystallinity is high in a short time (within 1 hour), and high luminance and long afterglow characteristics are obtained. Can be
[0013]
However, when each of Cl, Br, and I, which are halogen elements other than fluorine, is contained in the same production method as in the example of the present invention, the same effect as when fluorine is contained in the present invention cannot be obtained. Was.
As a fluorine source, NH₄  F, SrF₂  , LiSiF₅  , KF, MnF₂  , CaF₂  , SrF₂  , ZnF₂  , KTiF₆  In addition to the above, any compound containing fluorine can be used, but it is essential that the added fluorine forms a solid solution in the phosphorescent material at a certain rate in the manufacturing process. In particular, the firing conditions (temperature, time, atmosphere, temperature, Temperature rate, etc.) to determine what intermediate products are formed and how they affect crystal growth and the formation of defect structures. It is important to select the firing conditions and the type of fluorine source.
[0014]
In the present invention, lithium fluoride can be strongly recommended as an optimal fluorine source. However, in consideration of the above requirements, safety in production management is lower than that of other fluorine-containing compounds. It is based on the judgment that the stability and reproducibility of the luminous body quality are high and the reaction can be easily controlled.
In the case of using lithium fluoride only in the production process described in the examples, the amount of addition is suitably 0.5 to 5% by weight of the starting material, and preferably 1 to 2% by weight. The firing temperature is preferably 1300 ° C. or less, and the firing time is preferably within 2 hours.
[0015]
When boron is added simultaneously, that is, when 0 ≦ x ≦ 0.1 in the above composition formula, the amount of fluorine added to obtain a single phase as a phosphor after firing is 0.07 mol or less based on 1 mol SrO. become. In order to obtain predetermined luminous characteristics and heat / water resistance characteristics with the obtained phosphor, the fluorine content x of the above composition formula is preferably 0.01 to 0.08 mol, and if it is more than that, a small amount of fluorine compound is used. Mixed as two phases.
When fluorine is not added, the preferable addition amount of boric acid is 5 to 8 wt%. When fluorine and boron are added simultaneously, the optimum addition amount of boric acid is 1 to 2 wt%.
When fluorine and boron are added at the same time, the performance as a light storage unit with extremely high luminance and long afterglow is obtained. In addition to this light emission behavior, it has been found that water resistance and heat resistance are also effective.
[0016]
Hereinafter, other compositions of the phosphor of the present invention will be sequentially described.
E ': Mn, Zn, Bi, Ca, Mg, and Ba elements can be used singly or in combination as the constituent E' in the composition formula. The amount (molar value) of the element E ′ is in the range of 0 ≦ n ≦ 0.1, preferably 0.001 ≦ n ≦ 0.05. The emission luminance decreases when Ba and Ca are used, and the emission luminance increases when Mn, Zn, Bi, and Mg are used. In particular, the effect of the solid solution of Bi is great, and an appropriate charge transfer state can be formed. By forming an effective excitation relaxation process, the light emission luminance of the phosphor can be significantly improved.
[0017]
Eu: Light-emitting center Eu²⁺Is suitable in the range of 0 <m ≦ 0.05, preferably 0.001 ≦ m ≦ 0.01. When the m value is less than 0.0001, a predetermined emission intensity cannot be obtained because the amount of ions serving as the emission center is small. When the m value exceeds 0.05, density quenching becomes visible, and the light storage characteristics are significantly deteriorated.
Ln: The coactivator Ln is suitably in the range of 0 <k ≦ 0.1, preferably in the range of 0.001 ≦ k ≦ 0.03. In particular, Dy³⁺Has an optimum value depending on the amount of Eu added, and the optimum value is 1.5 times the number of moles of Eu. Dy³⁺And Y³⁺The combined use of the above shows improvement in emission luminance and long afterglow.
[0018]
The reason why the simultaneous addition of fluorine and boron has enabled high-brightness, long afterglow, water and heat resistance, and short-time sintering at a low temperature to be possible is considered as follows.
(1) Effect when added simultaneously;
LiF, CaF₂  , NH₄  F, LiSiF₅  Fluorine-containing compounds, such as alkali-containing carbonates, chlorides, borides, and the like, are often used as fluxes during the firing reaction, and have the effect of lowering the temperature during crystal growth, diffusion reaction, and firing reaction. It has been known. Usually, an amount of several wt% to 10 wt% of the reactant is used as the flux. For example, SrO.rAl₂  O₃  : In the Eu, Dy phosphor, 3 wt% to 10 wt% of boric acid is added to the starting material. It has been found that boron is partially replaced by solid solution at the Al site, which is useful for grain growth as a flux of dissolution and precipitation, and contributes to high luminance and long afterglow.
[0019]
However, when boron is added to a luminous body that emits light at 510 to 520 nm synthesized without adding boron, the maximum emission wavelength shifts to 490 nm. As a flux that does not change the light emission characteristics, lithium fluoride is optimal. In addition, when 3 to 8 wt% of lithium fluoride is added to the starting material, the optimal firing temperature is lowered from 1500 ° C. to 1250 ° C. In addition, a phosphorescent body having efficient light emission characteristics can be obtained in a short time.
When lithium carbonate is added instead of lithium fluoride, the firing reaction temperature decreases, but the light emission characteristics deteriorate. Then, another fluorine-containing compound such as NH₄  F, LiSiF₅  With regard to, it has been found that although it acts as a flux, the crystallinity and the heat and water resistance are improved, but the luminescent properties as a luminous body, especially the long afterglow, are not improved as much as lithium fluoride.
[0020]
In conclusion, the addition of fluorine makes it possible to control the crystal growth and diffusion reaction at a low temperature, and furthermore, Eu as an emission center²⁺Ln of ion and coactivator³⁺It was found that it contributed to the uniform distribution of ions to the lattice and contributed to high brightness and long afterglow.
1 to 3 show scanning electron micrographs of the fracture surface of the phosphor sample fired at 1250 ° C. for 2 hours. 1 shows a sample to which neither boron nor fluorine was added, FIG. 2 shows a sample to which fluorine was added, and FIG. 3 shows a sample to which boron and fluorine were added simultaneously. In the sample in which 1 wt% of lithium fluoride and 1 wt% of boric acid are added as shown in FIG. 3, it can be seen that the crystal has a size of 3 to 10 μm, and shows a remarkable growth as compared with the others.
[0021]
(2) lattice distortion effect;
Table 1 summarizes the lattice constants and firing conditions of the monoclinic phosphor.
In the table, SrAl₂  O₄  Then, 0%, 1% by weight, and 3% by weight of lithium fluoride were added to the starting materials, and 1% by weight of lithium fluoride and 3% of boric acid were added. After mixing and molding, the mixture was calcined at 1250 ° C. for 2 hours. These are designated SAF0, SAF1, SAF3, and SABF1, respectively.
Also, Sr_0.987  Eu_0.005  Dy_0.008  Al₂  O₄  : B_0.041  Then, 0%, 1%, 3% by weight, and 5% by weight of lithium fluoride were added to the starting material and calcined at 1250 ° C. for 2 hours to obtain SAEDBF0, SAEDBF1, SAEDBF3, and SAEDBF5.
[0022]
The lattice constant obtained from the powder X-ray diffraction pattern is considered to be small due to solid solution substitution of fluorine, and it is considered that crystal distortion occurred due to peak broadening. Can be
[0023]
[Table 1]

[0024]
A sample in which 1 wt% lithium fluoride was added and baked at 1250 ° C. for 2 hours was a single-phase SrAl₂  O₄  As a result of chemical analysis, it was found to contain 0.058 mol of fluorine. On the other hand, after adding 5 wt% of lithium fluoride and sintering at 1250 ° C. for 2 hours, the sample obtained was SrF₂  Was mixed. On the other hand, by re-firing, SrAl₂  O₄  A single phase having the same peak as was obtained.
From the above results, it was found that the added lithium fluoride F⁻  Is the phosphorescent O^2-Partly replaced with O^2-It is considered that while the density of the killer center decreased, some lattices were distorted, and the luminance was improved.
[0025]
(3) charge balance effect;
By simultaneously adding boron and fluorine, SrO.rAl₂  O₃  : Eu, Dy phosphor is a more activated parent, a more activated Eu²⁺Light emitting center and Ln³⁺Uniform dispersion with the co-activator can be realized. As a result, effective energy transfer is performed, which contributes to high-luminance light emission performance. Reactively, in the presence of fluorine and boron, SrCO₃  → SrO + CO₂  The reaction of 促 is further promoted, and the generated SrO is rich in reactivity.₂  O₃  Reaction can be completed in a short time. Furthermore, the presence of fluorine is Eu²⁺Has contributed to the stability.
[0026]
(4) stabilizing effect of oxygen deficiency;
It is considered that lattice instability caused by oxygen ion deficiency is trapped not by hydroxide ions but by fluorine ions, thereby preventing dissolution of the phosphor particles and improving heat resistance and water resistance.
[0027]
(5) luminescence behavior;
1). All of the starting materials to which 1 wt% to 5 wt% of lithium fluoride are added have a maximum excitation wavelength of 205 nm to 208 nm and a maximum emission wavelength of 512 nm to 517 nm. In addition, it was observed that the half-width gradually increased from 75 nm to 80 nm with an increase in the amount of lithium fluoride added, and that the initial light emission luminance decreased as the crystallinity decreased.
Loss of fluorine during firing process (AlF₃  {, HF}) or SrF as a by-product₂  And the like, the composition of the phosphor is considered to be slightly shifted (non-stoichiometric ratio), and in addition, the crystallinity is improved by the influence of fluorine and boron incorporated into the lattice. The above addition lowers the luminance.
[0028]
2). SrAl without adding activator and co-activator₂  O₄  : In F, long light emission and afterglow were observed.
SrCO₃  And Al₂  O₃  Was weighed at an equimolar ratio, and a mixed powder containing 0%, 1% by weight, 3% by weight, and 5% by weight of lithium fluoride was molded into φ20, and was heated at 1250 ° C. for 2 hours and 3% H 2.₂  A sample (SABF) containing 1 wt% of lithium fluoride and 1 wt% of boric acid added simultaneously under the same conditions was fired in a contained argon gas, and as a result, the sample without lithium fluoride added had a volume after firing. There was almost no change, and no light emission was observed even under irradiation with an ultraviolet lamp. On the other hand, the other samples to which lithium fluoride was added considerably shrunk to exhibit a dense structure, exhibited blue-green fluorescence under ultraviolet excitation, and observed afterglow after the excitation was stopped. In particular, the SABF sample had high emission intensity and long persistence.
Such a high-efficiency light-emitting composition is added to Eu.²⁺, Dy³⁺When activated, they exhibit excellent luminous properties.
[0029]
The present invention is characterized in that crystal addition is remarkable by simultaneous addition of fluorine and boron, and a phosphorescent body which can stably maintain high luminance and long afterglow even with fine powder can be obtained. The emission luminance and the afterglow of the conventional phosphor are affected by the particle size of the powder, and the finer the particles, the worse the emission luminance and the afterglow. For example, comparing a phosphor having average particle diameters of 10 μm and 30 μm, the luminance at 3 minutes after excitation is 60: 100, but the sample of the present invention has an extremely small influence of particle diameter of 95: 100.
Furthermore, in the present invention, by the simultaneous addition of fluorine or fluorine and boron, the hardness of the sintered body is lower than that of a conventional sintered body to which only boric acid is added, so that the pulverization step is easy and the productivity is increased. There is also a feature.
[0030]
Further, it is possible to bake at a lower temperature, and particularly when mixing and molding a phosphorescent powder and a resin, there is little contamination from a metal container or the like, and there is a great feature that deterioration of luminance can be prevented.
Furthermore, since low-temperature sintering is possible, a tunnel-type continuous furnace can be used from the current batch-type furnace, and equipment costs can be increased because heat-resistant stainless steel can be used as a furnace material. It becomes easy to systematize for mass production at low cost.
[0031]
【Example】
EXAMPLES Hereinafter, the present invention will be described in more detail with reference to Examples. Prior to the description, methods for measuring afterglow luminance, a heat resistance test, and a water resistance test in the following Examples will be described.
[0032]
First, the method of measuring the afterglow luminance is as follows.
The phosphor powder of the embodiment or the comparative example is uniformly mixed with a polyester resin or the like, and the phosphor is molded into a sheet having a thickness of 2.5 mm in a weight ratio of [phosphor phosphor: polyester resin] of 1: 2. After drying, this is used as a sample for measuring the change over time in the emission intensity. The measurement is performed by irradiating a measurement sample placed in a dark room for 24 hours after blocking light with a 15 W white fluorescent lamp from a vertical distance of 100 mm for 15 minutes, and then measuring the change with time of the emission luminance. Tables 2 and 3 show the measurement results.
[0033]
The method of the heat resistance test is as follows.
5 g of a phosphorescent powder having a size of 300 μm or less was weighed, placed in an alumina crucible, and oxidized and fired in an electric furnace at 800 ° C. and 900 ° C. for 1 hour in the air, and the emission luminance was measured. A luminance maintenance ratio with respect to the afterglow luminance is obtained. Table 4 shows the measurement results.
The luminous body obtained in the present invention still exhibited a luminance maintenance ratio of 70% or more even when heated at 900 ° C. in the atmosphere. In addition, a phosphor having a size of 10 mm × 10 mm × 20 mm was oxidized and fired in the air at 1200 ° C. for 180 minutes. In this case, the retention was about 43%.
[0034]
The method of the water resistance test is as follows.
200 ml of pure water is put into a 300 ml beaker, 10 g of a phosphor powder of 300 μ under is added, impregnated for 24 hours, dried, the afterglow luminance is measured, and the luminance maintenance ratio with respect to the afterglow luminance before water treatment is obtained. . Table 5 shows the measurement results.
[0035]
[Reference Example 1]
Sr_0.987 Eu_0.005 Dy_0.008 Al₂ O₄ : B_0.041 F_0.058 SrCO as a starting material powder (purity 99.9%) so that the quantitative ratio of the chemical composition formula₃ , Al₂ O₃ , Eu₂ O₃ , Dy₂ O₃ , H₃ BO₃ , LiF, respectively,
SrCO₃ = 0.987 × 147.63 = 145.71 g
Al₂ O₃ = 1 × 101.96 = 101.96 g
Eu₂ O₃ = 0.005 x 1/2 x 351.93 = 0.88 g
Dy₂ O₃ = 0.008 x 1/2 x 373.000 = 1.49 g
H₃ BO₃ = 0.041 x 61.83 = 2.54 g
LiF = 0.098 × 25.94 = 2.54 g
Each of them was accurately weighed, and wet-mixed with pure water for 24 hours using a ball mill.
[0036]
Next, it was dried at 140 ° C. to obtain a mixed powder. The mixed powder was packed in an alumina heat-resistant container and fired at 1100 ° C. for 1 hour in an argon gas containing 3% of hydrogen in an electric furnace of a stainless steel furnace tube. After cooling, the collected sample was crushed to obtain the phosphor powder of the present invention.
As a result of chemical analysis, the fluorine content was 0.058 mol. The powder X-ray diffraction method was able to index a single-phase monoclinic system. In addition, according to SEM observation, it was observed that the phosphor had high crystallinity despite the low-temperature and short-time firing step.
[0037]
FIG. 4 shows an emission spectrum when excited by ultraviolet light of 260 nm. This is a yellow-green luminescent color phosphor having a maximum emission wavelength near 512 nm.
In order to measure the time change of the luminescence intensity, 1.25 g of the phosphor powder having a particle size of 300 μm or less and 2.5 g of the polyester resin are weighed, uniformly mixed, and molded into a sheet having a thickness of 2.5 mm. Then, a dried product was prepared, and the change in the emission intensity after the excitation was stopped was measured by the method described above. The results are shown in the column of Example 1 in Table 2. Table 4 shows the results of the heat resistance test.
[0038]
[Example or Reference Example2-18]
Table 2 shows specific chemical composition formulas and firing conditions of Examples or Reference Examples 2 to 18. In these examples, as in Example 1, the necessary starting material powder SrCO₃ , CaCO₃ , Al₂ O₃ , Eu₂ O₃ , Dy₂ O₃ , Y₂ O₃ , Sm₂ O₃ , Tm₂ O₃ , H₃ BO₃ , LiF, MgO, MnO, ZnO, Bi₂ O₃ Was weighed, mixed with pure water and wet with a ball mill for 24 hours, and then dried at 140 ° C. to obtain a mixed powder. This was placed in a carbon crucible and fired in a 3% hydrogen-containing nitrogen gas using an electric furnace made of alumina furnace material. Each sample was pulverized after cooling, and particles having a size of 300 μm or less were classified by sieving to obtain a phosphorescent material of the present invention.
[0039]
theseExamples, Reference ExamplesTables 2 and 3 show the change in emission luminance over time (afterglow luminance) of the comparative examples described below, and Tables 4 and 5 show the luminance maintenance rates in the heat and water resistance tests.
In the heat resistance test by heat treatment at 800 ° C. for 1 hour in the air, as shown in the heat resistance test results in Table 4, the luminous bodies of the examples of the present invention maintain high luminance and 3 minutes after the excitation is stopped. Showed a maintenance rate of 83% or more before the heat treatment. On the other hand, all the samples used as comparative examples turned white, and the luminance retention ratio was 1% or less.
As for the water resistance, the luminous body of the present invention exhibited a retention of 85% or more, and the sample of the comparative example had a retention of about 6.2%.
[0040]
[Table 2]

[0041]
[Table 3]

[0042]
[Table 4]

[0043]
[Table 5]

[0044]
In a conventional aluminate phosphor, boron is an essential additive composition, whereasIn Reference Examples 17 and 18,Even if it contains only fluorine, it has high light emission performance.
[0045]
[Comparative Example 1]
Sr_0.987 Eu_0.005 Dy_0.008 Al₂ O₄ : B_0.041 The phosphor of Comparative Example 1, which does not contain fluorine, having the chemical composition of was obtained as follows.
The following starting material powder having a purity of 99.9% was weighed,Reference Example 1, And prepared as shown in Table 2 by firing at 1400 ° C. for 2 hours.
SrCO₃         145.71 g
Al₂ O₃         101.96 g
Eu₂ O₃             0.88g
Dy₂ O₃             1.49g
H₃ BO₃             2.54g
[0046]
Tables 2 to 5 show the luminous characteristics and the results of the water resistance / heat resistance tests of the obtained samples. As shown in Table 3, the sample of Comparative Example 1As compared with Reference Example 4,Both the luminance and the afterglow were low, and further, as shown in Table 4, when heated at 800 ° C. in the air, it turned white and lost its light emitting performance. Further, as shown in Table 5, in the water resistance test in which the water treatment was performed for 24 hours, the afterglow luminance after the excitation was stopped was low, and the maintenance ratio was about 6.2%.
[0047]
[Comparative Example 2]
Sr_0.975 Eu_0.01Dy_0.015 Al₂ O₄ The phosphor of Comparative Example 2 which does not contain fluorine and boron having the chemical composition ofReference Example 1As shown in Table 2, it was manufactured by firing at 1500 ° C. for 2 hours using the same method. As shown in Table 2, the luminous body of Comparative Example 2 had significantly reduced light emission luminance and afterglow.
[0048]
【The invention's effect】
According to the present invention described in detail above, a fluorine-containing yellow-green luminescent phosphor having excellent water resistance and heat resistance, extremely high initial luminance and long afterglow characteristics can be obtained. In addition, conventional SrAl₂  O₄  : The content of fluorine and boron is higher than that of Eu and Dy, so that pulverization is easy, a powder product is easily obtained, and it is also useful for preventing contamination of metal powder.
Further, the production method of the present invention maintains a high luminance and has a process suitable for producing a fine powdery phosphor, and as in the related art, a high-temperature and long-time firing condition is reduced to a lower temperature and a shorter time. The time can be reduced, and favorable conditions for mass production such as energy saving and productivity improvement are provided.
[Brief description of the drawings]
FIG. 1 is a scanning electron micrograph instead of a drawing of a fractured surface of a fired phosphor sample when fluorine and boron are not added.
FIG. 2 is a scanning electron micrograph instead of a drawing of a fractured surface of a burned phosphor sample when only fluorine is added.
FIG. 3 is a scanning electron micrograph instead of a drawing of a fractured surface of a fired phosphor sample when both fluorine and boron are added.
FIG. 4Reference exampleFIG. 2 is a view showing an emission spectrum (excitation wavelength: 260 nm, emission wavelength: 512 nm) of the phosphor obtained in Step 1.

Claims (3)

The composition formula is
_{(Sr 1-n-m-} k-q E 'n Eu m Ln k Y q) Al 2 O 4: B x, F y
(However, 0 ≦ n ≦ 0.1
0 <m ≦ 0.05
0 <k ≦ 0.1
0 <q ≦ 0.05
0 ≦ x ≦ 0.1
0 <y ≦ 0.1
Wherein E ′ is at least one metal element selected from the group consisting of Mn, Zn, Bi, Ca, Mg, and Ba, and Ln is Ce, Pr, Gd, Tb, Dy, Ho, Er, One or more lanthanoid elements selected from the group consisting of Tm, Yb, and Lu)
A heat-resistant, water-resistant, high-brightness, and long-lasting yellow-green luminescent phosphor mainly composed of strontium aluminate containing fluorine and represented by a monoclinic system. The composition formula is
_{(Sr 1-n-m-} k-q E 'n Eu m Ln k Y q) O · rAl 2 O 3: B x, F y
(However, 0 ≦ n ≦ 0.1
0 <m ≦ 0.05
0 <k ≦ 0.1
0 <q ≦ 0.05
1 ≦ r ≦ 1.50
0 ≦ x ≦ 0.1
0 <y ≦ 0.1
Wherein E ′ is at least one metal element selected from the group consisting of Mn, Zn, Bi, Ca, Mg, and Ba, and Ln is Ce, Pr, Gd, Tb, Dy, Ho, Er, One or more lanthanoid elements selected from the group consisting of Tm, Yb, and Lu)
A heat-resistant, water-resistant, high-brightness, and long-lasting yellow-green luminescent phosphor mainly composed of strontium aluminate containing fluorine and represented by a monoclinic system. Sr, Al, Eu, Y, E ', Ln, and B elements (where E' is one or more metal elements selected from the group consisting of Mn, Zn, Bi, Ca, Mg, and Ba; Ln is Ce, A simple powder or a compound powder or solution containing at least one lanthanoid element selected from the group consisting of Pr, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu.
_{(Sr 1-n-m-} k-q E 'n Eu m Ln k Y q) Al 2 O 4: B x, F y, _{or, (Sr 1-n-m} -k-q E' n Eu m _{ln k Y q) O · rAl} 2 O 3: B x, F y
(However, 0 ≦ n ≦ 0.1
0 <m ≦ 0.05
0 <k ≦ 0.1
0 <q ≦ 0.05
1 ≦ r ≦ 1.50
0 ≦ x ≦ 0.1
0 <y ≦ 0.1)
While weighing so as to have a composition ratio of the composition formula, firing the compound powder or solution containing the F element and weighing so as to have a composition ratio of the above composition formula as a starting material, and mixing them, The mixed powder obtained by drying and pulverization is put into a heat-resistant container, molded, or baked at 1000 ° C. to 1500 ° C. in a reducing atmosphere for 30 minutes to 2 hours in a reducing atmosphere. A method for producing a fluorine-containing strontium aluminate heat-resistant, water-resistant, high-brightness, long-persistent yellow-green luminescent color phosphor that is pulverized into a powder.

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