JP2004207100A

JP2004207100A - Binder and fluorescent lamp using it

Info

Publication number: JP2004207100A
Application number: JP2002376197A
Authority: JP
Inventors: Kazunari Nishida; 一成西田; Hideo Narukawa; 英男成川
Original assignee: Nichia Chemical Industries Ltd
Current assignee: Nichia Chemical Industries Ltd
Priority date: 2002-12-26
Filing date: 2002-12-26
Publication date: 2004-07-22
Anticipated expiration: 2022-12-26
Also published as: JP4311016B2

Abstract

<P>PROBLEM TO BE SOLVED: To provide a boric acid strontium binder and its binder slurry which can strengthen the adhesion of a phosphor and have no discoloration after baking, and little change with the passage of time, and a fluorescent lamp using the same. <P>SOLUTION: A precipitate is generated by adjusting the pH of an aqueous solution containing water soluble strontium salt, boric acid, and base in the range of 7.5-10, and baked at 600-900°C, by the above, a boric acid strontium binder having an average particle size of 0.5-5.0 μm is obtained. When this binder is used, the adhesive force of the phosphor is strengthened, and there occurs no discoloration after baking, and the change with the passage of time can be made small, therefore, especially in the circular fluorescent lamp, the adhesion between the phosphor and the glass tube can be greatly improved, and a fluorescent lamp having superior lamp light flux can be stably manufactured. Furthermore, the yield at the manufacturing process can be improved owing to it. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

【０００１】
【産業上の利用分野】
本発明は結着剤及びそれを用いた蛍光ランプに関し、特に蛍光体の接着力を強くでき、ベーキング後の変色が無く、経時変化の少ないホウ酸ストロンチウム結着剤とその結着剤スラリー、及びそれを用いた蛍光ランプに関する。
【０００２】
【従来の技術】
従来より、蛍光体を蛍光ランプのガラス管内面に被着させる場合、バインダーとしてニトロセルロースを酢酸ブチルに溶解した溶液に蛍光体を懸濁し、これをガラス管内面に塗布し、乾燥、焼成工程を経て蛍光体層を形成している。しかしながら、近年、省資源、省エネルギー、作業環境、防災等の問題から水溶性バインダーを用いる傾向にある。
【０００３】
一般に、水溶性バインダーは従来の有機溶剤のバインダーに比べ、ガラス管への蛍光体の付着強度が弱くなるという欠点があり、蛍光体層がガラス管より簡単に剥離してしまう。しかも、環形用蛍光ランプでは、赤熱されたガラス管（鉛ガラスの場合は６５０〜７００℃）が環状に成形されるとき伸びを生ずるため、上述した剥離現象がさらに顕著になる。
【０００４】
このような水溶性バインダーを用いて水性塗布する際、結着剤として従来から用いられているホウ酸カルシウム・バリウムを使用した場合、水溶性が高いため、結着剤スラリー中の粒子が凝集して粘度が経時的に上昇し、結着剤スラリーを長時間保管後使用すると接着力及びランプ光束が低下し、使用が困難となる問題があった。また、このホウ酸塩は６５０℃付近で軟化するため、水性塗布後ベ−キング時に水溶性バインダーが軟化した結着剤に包み込まれて十分熱分解されず、カーボンが残留し融着して蛍光体層が茶褐色に変色し、蛍光ランプの初期光束が低下するという問題があった。他のアルミナ、シリカ、りん酸塩などの結着剤は、直管用蛍光ランプの水性塗布には使用できるが、環形用には接着力に問題があった。
【０００５】
これに対し、特開昭５７−１０８１８８号公報には、上記ホウ酸塩にリン（Ｐ）を導入したホウ・リン酸カルシウム・バリウムは、被着力及び光束の低下を招くことなく耐水性を向上させることが開示されている。しかしながら、接着力、ランプ光束、耐水性は未だ十分でなく、特に環形用蛍光ランプではさらに改善が望まれていた。
【０００６】
【特許文献１】
特開昭５７−１０８１８８号公報
【０００７】
【発明が解決しようとする課題】
従って、本発明は上述した問題を解決することを目的とし、蛍光体の接着力を強くでき、ベーキング後の変色が無く、経時変化の少ないホウ酸ストロンチウム結着剤とその結着剤スラリー、及びそれを用いた蛍光ランプを提供することを目的とする。
【０００８】
【発明を解決するための手段】
本発明者等は、上述した目的を達成するために、環形用蛍光ランプに用いる最適な結着剤の化学組成について膨大な試験を行い鋭意検討した結果、平均粒径が０．５〜５．０μｍの範囲のホウ酸ストロンチウム結着剤が適当であることを見い出し、本発明を完成させるに至った。
【０００９】
本発明のホウ酸ストロンチウム結着剤スラリーは次のようにして得られる。先ず、水溶性ストロンチウム塩１ｍｏｌに対し、ホウ酸を１〜４ｍｏｌ添加し、水溶液とする。ホウ酸は１ｍｏｌより少ないと結着剤の収率が低下し、４ｍｏｌより多いと過剰に加えるホウ酸の損失が大きくなるためである。この水溶液にアンモニア水等の塩基を加えｐＨを７．５〜１０の範囲に、好ましくは８．５〜９．５の範囲に調節し、ホウ酸ストロンチウムを生成させる。或いは、ホウ酸にアンモニア水等の塩基を加えて溶解した水溶液と水溶性ストロンチウム塩の水溶液を混合し、ｐＨを７．５〜１０の範囲、好ましくは８．５〜９．５の範囲で反応させてホウ酸ストロンチウム沈殿物を生成させる。ｐＨが７．５より低いと結着剤の収率が低下し、ｐＨを１０より高くしても収率は変わらないため、それ以上塩基を加える必要はない。
【００１０】
次に、得られたホウ酸ストロンチウム沈殿物を固液分離し、ケーキを水洗し、乾燥した後、これを６００〜９００℃の範囲で、好ましくは７００〜８００℃の範囲で焼成する。焼成温度が６００℃より低いと結着剤の平均粒径が０．５μｍより小さくなり、逆に９００℃より高いと平均粒径が５．０μｍより大きくなって、目的の粒径の結着剤が得られないからである。焼成品を粗粉砕して、本発明のホウ酸ストロンチウム結着剤を得る。結着剤の平均粒径は０．５〜５．０μｍの範囲が好ましく、１．０〜３．０μｍの範囲がより好ましい。０．５μｍより小さいとスラリーにしたときに粒子が凝集して粘度が高くなってしまうからであり、逆に５．０μｍより大きいと接着力が低下するからである。この結着剤を水中でボールミル等により十分粉砕することで懸濁し、本発明のホウ酸ストロンチウム結着剤スラリーを得る。このスラリーの中心粒径は２．０μｍ以下が好ましく、１．５μｍ以下がより好ましい。２．０μｍより大きいと接着力が低下してしまう。
【００１１】
また、この結着剤スラリーは実用上固形分で３〜３０重量％の範囲に調製する。なぜならば、この範囲より濃度が低いと結着剤スラリーを多く加えなければならなくなり、蛍光体塗布スラリー濃度が低下してしまうからで、また、この範囲よりも濃くなると、分散しにくくなるためである。
【００１２】
本発明の環形用蛍光ランプは次のような方法で製造する。先ず、蛍光体を水溶性バインダー溶液に懸濁させ、これに本発明のホウ酸ストロンチウム結着剤スラリーを加え蛍光体塗布スラリーとする。次に、これをガラス管の内面に通常の方法で塗布し、乾燥し、ベーキングして蛍光体層を形成する。その後、７００〜９００℃に加熱して環状に成形し、電極の装着、排気等の工程を経て本発明の環形用蛍光ランプを得る。
【００１３】
本発明の結着剤は適量があり、塗布スラリー中の蛍光体に対しその添加量が０．１重量％より少ないと、本発明の効果は殆どなく、逆に、添加量が６重量％より多くなると、ランプの初期光束が低下してしまい実用的でない。すなわち本結着剤の適量は蛍光体に対し６重量％以下であり、好ましくは０．１〜６重量％の範囲、より好ましくは１〜３重量％の範囲である。
【００１４】
また、ホウ酸ストロンチウムの結着剤に微粒子アルミナの結着剤を併用することで接着力はさらに改善される。しかし、アルミナの添加量があまり多くなると、光束が低下する問題があり、適量はホウ酸ストロンチウム結着剤量とアルミナ結着剤量の和が蛍光体に対し６重量％以下であり、アルミナ量はホウ酸ストロンチウム量以下に抑えることが好ましい。
【００１５】
本発明の結着剤スラリーが接着力に優れている理由は、以下に説明するように微粒子のホウ酸ストロンチウムが結着剤として機能しているためである。これが蛍光体間あるいは蛍光体とガラスの間の間隙に入り、ファン・デル・ワールス力が大きく影響することで、結着剤としての効果を発揮する。接着力はその測定の方法から大きく分けて２種類あり、一つは蛍光ランプの外表面に衝撃を与えて蛍光体層の剥離を調べる方法、もう一つは蛍光体層に直接ノズルからの圧空をあて、吹き飛んだ蛍光体層の程度を調べる方法である。本発明の結着剤スラリーを使用すると、いずれの接着力の向上にも効果的である。
【００１６】
また、本発明のホウ酸ストロンチウム結着剤スラリーは、従来のホウ酸カルシウム・バリウム結着剤スラリーに比べ、経時変化が非常に少ない。結着剤１ｇの純水５０ｍｌへの溶出量は、従来のホウ酸カルシウム・バリウムがＣａ２．５％、Ｂａ１３％、Ｂ２０％に対し、本発明で得られるホウ酸ストロンチウムは、Ｓｒ１．１％、Ｂ１．２％と非常に少なく、この結着剤スラリーを４日間保管しても粘度の上昇は無く、スラリー作製時と同様に使用することができる。
【００１７】
次に、上記結着剤の軟化温度を調べると、従来のホウ酸カルシウム・バリウムが６５０℃付近で軟化するのに対し、本発明で得られるホウ酸ストロンチウムは７５０℃付近で軟化し、軟化温度が１００℃近く高くなっており、水溶性バインダーの分解温度（５００〜６００℃）よりかなり高いので、ベーキング後の変色が無く、ランプ光束の低下も見られない。
【００１８】
【実施例】
［実施例１］
ＳｒＣｌ_２４５６ｇを純水に溶解して３．８リットルとし、液温４５℃に調節して塩化ストロンチウム水溶液を調製する（ｐＨ７．０）。次に、Ｈ_３ＢＯ_３５００ｇ、ＮＨ_３１６０ｇを純水に溶解して３．５リットルとし、液温４５℃に調節してホウ酸水溶液を調製する（ｐＨ９．６）。次に、ホウ酸水溶液と塩化ストロンチウム水溶液を混合し、ｐＨを９で反応させてホウ酸ストロンチウムの沈殿を得る。これをヌッチェで固液分離し、固形分を１００℃で１５時間乾燥する。これをさらにマッフル炉で８００℃で１時間焼成する。焼成品を粗粉砕して平均粒径が１．０μｍのホウ酸ストロンチウムを得る。ここで、平均粒径は空気透過法によるフィッシャー・サブ・シーブ・サイザー（Ｆ.Ｓ.Ｓ.Ｓ）を用いて測定する。この１００ｇと純水４００ｇを混合し、ボールミルにより２時間湿式粉砕し、中心粒径が１．０μｍの結着剤スラリーを得る。ここで、スラリーの中心粒径は自然・遠心沈降式自動粒度測定装置を用いて測定する。
【００１９】
白色のハロリン酸カルシウム蛍光体１０００ｇを０．６ｗｔ％ポリエチレンオキサイド水溶液１０００ｇに懸濁させ、これに本発明の結着剤スラリーを１００ｇ添加し、十分に撹拌し全体を均一に混合し、フルイを通し蛍光体塗布スラリーを得る。このスラリー中に含まれるホウ酸ストロンチウム結着剤は蛍光体に対し２重量％である。
【００２０】
次に、外径３２ｍｍφ４０ワット蛍光ランプ用ガラス管に、得られた蛍光体塗布スラリーを一様に流し込み、温風で乾燥させ蛍光体層を形成する。これを通常の方法で蛍光体の付着量がガラス１本あたり４．５〜５．０ｇの範囲になるように調節する。次に、これを６２０℃の温度で５分間ベーキングし有機バインダーを除去する。８８０℃に加熱して環状に成形し、ガラス管が冷却された後、通常の方法に従ってガラス管内を真空排気し、希ガス及び水銀を封入し、口金を取り付けて環形用蛍光ランプを得る。
【００２１】
得られた蛍光ランプについて、接着力、初期光束について測定し結果を表１にまとめる。ここで、接着力については排気時の蛍光体層の剥がれ不良を比較する為に、次のように実際より強力な条件で強制試験する。蛍光体を塗布し６２０℃で５分間ベーキング後さらに８８０℃で４５分間焼成した蛍光面に５ｍｍ離した位置の吹き出し口が３ｍｍφのノズルから、１．２ｋｇ／ｃｍ²の圧で空気を０．５秒間噴出させ、吹き飛んだ蛍光体層の直径を測定する。従って、この直径が小さい程接着力が大きいことになる。本実施例において接着力は５０ｍｍφであり、初期光束は６１９５ルーメンである。次に、この実施例で得られる結着剤スラリーを４日間保管した後、蛍光ランプを作製し、同様に接着力と初期光束を測定すると、接着力は５０ｍｍφと変わらず、初期光束も６１９４ルーメンとほとんど差は見られない。また、他の実施例でも同様な結果が得られる。
【００２２】
【表１】

【００２３】
また、３００ｇの荷重を有するピアノ線で蛍光ランプの外表面に衝撃を与えた時に生ずる蛍光体層の剥離した部分の平均直径について測定した場合も、本実施例、他の実施例で蛍光体層の脱落は見られない。
【００２４】
［実施例２］
焼成温度を６００℃にする以外は実施例１と同様に行い、平均粒径が０．５μｍのホウ酸ストロンチウム、中心粒径が０．５μｍの結着剤スラリーを得る。
【００２５】
［実施例３］
焼成温度を９００℃にする以外は実施例１と同様に行い、平均粒径が５．０μｍのホウ酸ストロンチウム、中心粒径が１．５μｍの結着剤スラリーを得る。
【００２６】
【発明の効果】
以上に述べたように、本発明の結着剤を使用すると、蛍光体の接着力を強くでき、ベーキング後の変色が無く、経時変化を少なくすることができるため、特に環形用蛍光ランプにおいて、蛍光体とガラス管の間の接着力を大きく向上でき、ランプ光束の優れた蛍光ランプを安定して製造することができる。また、そのことで製造工程の歩留まりを向上することができる。[0001]
[Industrial applications]
The present invention relates to a binder and a fluorescent lamp using the same, in particular, a strontium borate binder and a binder slurry thereof, which can enhance the adhesion of the phosphor, have no discoloration after baking, and have little change over time, and The present invention relates to a fluorescent lamp using the same.
[0002]
[Prior art]
Conventionally, when a phosphor is applied to the inner surface of a glass tube of a fluorescent lamp, the phosphor is suspended in a solution in which nitrocellulose is dissolved in butyl acetate as a binder, and the suspension is applied to the inner surface of the glass tube, followed by a drying and firing process. After that, a phosphor layer is formed. However, in recent years, there has been a tendency to use a water-soluble binder due to problems such as resource saving, energy saving, work environment, disaster prevention and the like.
[0003]
In general, a water-soluble binder has a disadvantage that the adhesion strength of a phosphor to a glass tube is weaker than a conventional binder of an organic solvent, and the phosphor layer is easily peeled off from the glass tube. Moreover, in the ring-shaped fluorescent lamp, since the red-heated glass tube (650 to 700 [deg.] C. in the case of lead glass) is formed into an annular shape, the above-described peeling phenomenon becomes more remarkable.
[0004]
In the case of aqueous coating using such a water-soluble binder, when calcium / barium borate, which has been conventionally used, is used as a binder, particles in the binder slurry aggregate due to high water solubility. Therefore, when the binder slurry is used after being stored for a long time, the adhesive strength and the luminous flux of the lamp are reduced, and there is a problem that the use becomes difficult. In addition, since the borate softens at around 650 ° C, the water-soluble binder is wrapped in the softened binder during baking after aqueous coating, and is not sufficiently thermally decomposed. There is a problem that the body layer turns brown and the initial luminous flux of the fluorescent lamp decreases. Other binders such as alumina, silica, and phosphate can be used for aqueous application of a fluorescent lamp for a straight tube, but have a problem in adhesive strength for a ring type.
[0005]
On the other hand, JP-A-57-108188 discloses that borate, calcium phosphate, and barium in which phosphorus (P) is introduced into the above borate can improve water resistance without lowering the adherence and luminous flux. Is disclosed. However, the adhesive strength, lamp luminous flux, and water resistance are not yet sufficient, and further improvement has been desired especially for a ring-shaped fluorescent lamp.
[0006]
[Patent Document 1]
JP-A-57-108188
[Problems to be solved by the invention]
Therefore, an object of the present invention is to solve the above-mentioned problems, can enhance the adhesive force of the phosphor, does not discolor after baking, strontium borate binder with little change over time and its binder slurry, and An object of the present invention is to provide a fluorescent lamp using the same.
[0008]
[Means for Solving the Invention]
In order to achieve the above-mentioned object, the present inventors have conducted enormous tests on the chemical composition of an optimal binder used for a fluorescent lamp for an annular shape, and as a result of intensive studies, the average particle diameter was 0.5 to 5.0. A strontium borate binder in the range of 0 μm was found to be suitable, and the present invention was completed.
[0009]
The strontium borate binder slurry of the present invention is obtained as follows. First, 1 to 4 mol of boric acid is added to 1 mol of a water-soluble strontium salt to prepare an aqueous solution. If the amount of boric acid is less than 1 mol, the yield of the binder decreases, and if it is more than 4 mol, the loss of excessive boric acid increases. To this aqueous solution is added a base such as aqueous ammonia to adjust the pH to a range of 7.5 to 10, preferably 8.5 to 9.5, to produce strontium borate. Alternatively, an aqueous solution in which a base such as aqueous ammonia is added to boric acid and dissolved is mixed with an aqueous solution of a water-soluble strontium salt, and the mixture is reacted at a pH in the range of 7.5 to 10, preferably 8.5 to 9.5. To form a strontium borate precipitate. When the pH is lower than 7.5, the yield of the binder decreases, and when the pH is higher than 10, the yield does not change. Therefore, it is not necessary to add a base any more.
[0010]
Next, the obtained strontium borate precipitate is subjected to solid-liquid separation, and the cake is washed with water and dried, and then calcined in the range of 600 to 900 ° C, preferably in the range of 700 to 800 ° C. If the sintering temperature is lower than 600 ° C., the average particle size of the binder becomes smaller than 0.5 μm. Conversely, if the firing temperature is higher than 900 ° C., the average particle size becomes larger than 5.0 μm. Is not obtained. The fired product is roughly pulverized to obtain the strontium borate binder of the present invention. The average particle size of the binder is preferably in the range of 0.5 to 5.0 μm, and more preferably in the range of 1.0 to 3.0 μm. If the particle size is smaller than 0.5 μm, the particles aggregate when the slurry is formed, and the viscosity increases. If the particle size is larger than 5.0 μm, the adhesive strength decreases. This binder is suspended in water by sufficiently pulverizing it in a ball mill or the like to obtain a strontium borate binder slurry of the present invention. The center particle size of this slurry is preferably 2.0 μm or less, more preferably 1.5 μm or less. If it is larger than 2.0 μm, the adhesive strength will decrease.
[0011]
Further, this binder slurry is prepared in a range of 3 to 30% by weight in terms of solid content for practical use. The reason is that if the concentration is lower than this range, a large amount of binder slurry must be added, and the phosphor coating slurry concentration decreases, and if the concentration is higher than this range, it becomes difficult to disperse. is there.
[0012]
The annular fluorescent lamp of the present invention is manufactured by the following method. First, the phosphor is suspended in a water-soluble binder solution, and the strontium borate binder slurry of the present invention is added to the suspension to form a phosphor coating slurry. Next, this is applied to the inner surface of the glass tube by a usual method, dried, and baked to form a phosphor layer. Then, it heats to 700-900 degreeC and shape | molds in an annular shape, and obtains the fluorescent lamp for annular shapes of this invention through processes, such as installation of an electrode and exhaustion.
[0013]
The binder of the present invention has an appropriate amount, and if the addition amount is less than 0.1% by weight with respect to the phosphor in the coating slurry, the effect of the present invention is hardly obtained, and conversely, the addition amount is less than 6% by weight. If it increases, the initial luminous flux of the lamp decreases, which is not practical. That is, the appropriate amount of the present binder is not more than 6% by weight, preferably 0.1 to 6% by weight, more preferably 1 to 3% by weight based on the phosphor.
[0014]
Further, by using a binder of fine particle alumina in combination with a binder of strontium borate, the adhesive strength is further improved. However, if the added amount of alumina is too large, there is a problem that the luminous flux is reduced. An appropriate amount is that the sum of the amount of strontium borate binder and the amount of alumina binder is 6% by weight or less based on the phosphor, Is preferably suppressed to the amount of strontium borate or less.
[0015]
The reason why the binder slurry of the present invention has excellent adhesive strength is that fine strontium borate functions as a binder as described below. This enters the gap between the phosphors or between the phosphor and the glass, and exerts a great effect on the van der Waals force, thereby exhibiting an effect as a binder. Adhesive strength can be roughly classified into two types according to the method of measurement. One is to apply a shock to the outer surface of the fluorescent lamp to check the peeling of the phosphor layer, and the other is to apply pressure to the phosphor layer directly from the nozzle. In this method, the extent of the blown phosphor layer is examined. The use of the binder slurry of the present invention is effective for improving any adhesive strength.
[0016]
In addition, the strontium borate binder slurry of the present invention has very little change over time as compared with the conventional calcium borate / barium binder slurry. The amount of 1 g of the binder eluted in 50 ml of pure water is as follows: strontium borate obtained in the present invention has Sr 1.1%, whereas conventional calcium / barium borate has Ca 2.5%, Ba 13% and B 20%. B is very small at 1.2%. Even when this binder slurry is stored for 4 days, there is no increase in viscosity, and it can be used in the same manner as when preparing the slurry.
[0017]
Next, when the softening temperature of the binder was examined, the conventional calcium / barium borate softened near 650 ° C., whereas the strontium borate obtained in the present invention softened near 750 ° C. Is nearly 100 ° C. higher than the decomposition temperature of the water-soluble binder (500 to 600 ° C.), so that there is no discoloration after baking and no decrease in lamp luminous flux.
[0018]
【Example】
[Example 1]
456 g of SrCl ₂ is dissolved in pure water to 3.8 liters, and the liquid temperature is adjusted to 45 ° C. to prepare an aqueous strontium chloride solution (pH 7.0). Next, 500 g of H ₃ BO ₃ and 160 g of NH ₃ are dissolved in pure water to 3.5 liters, and the solution temperature is adjusted to 45 ° C. to prepare a boric acid aqueous solution (pH 9.6). Next, an aqueous solution of boric acid and an aqueous solution of strontium chloride are mixed and reacted at pH 9 to obtain a precipitate of strontium borate. This is subjected to solid-liquid separation with a Nutsche, and the solid content is dried at 100 ° C. for 15 hours. This is further fired in a muffle furnace at 800 ° C. for 1 hour. The calcined product is roughly pulverized to obtain strontium borate having an average particle size of 1.0 μm. Here, the average particle size is measured using a Fisher sub-sieve sizer (FSSS) by an air permeation method. This 100 g and 400 g of pure water are mixed and wet-pulverized by a ball mill for 2 hours to obtain a binder slurry having a center particle diameter of 1.0 μm. Here, the center particle size of the slurry is measured using a natural / centrifugal sedimentation type automatic particle size analyzer.
[0019]
1000 g of a white calcium halophosphate phosphor is suspended in 1000 g of a 0.6 wt% aqueous solution of polyethylene oxide, and 100 g of a binder slurry of the present invention is added thereto. The mixture is thoroughly stirred, and the whole is uniformly mixed. Obtain a body application slurry. The strontium borate binder contained in this slurry was 2% by weight based on the phosphor.
[0020]
Next, the obtained phosphor coating slurry is uniformly poured into a glass tube for a fluorescent lamp of 32 mm in diameter and 40 watts, and dried with warm air to form a phosphor layer. This is adjusted by an ordinary method so that the amount of the attached phosphor is in the range of 4.5 to 5.0 g per glass. Next, this is baked at a temperature of 620 ° C. for 5 minutes to remove the organic binder. After heating to 880 ° C. to form a ring, the glass tube is cooled, and then the inside of the glass tube is evacuated according to a usual method, a rare gas and mercury are sealed, and a base is attached to obtain a fluorescent lamp for a ring.
[0021]
The adhesive strength and the initial luminous flux of the obtained fluorescent lamp were measured, and the results are summarized in Table 1. Here, in order to compare the peeling failure of the phosphor layer at the time of exhaustion, the adhesive force is subjected to a compulsory test under stronger conditions as follows. From the nozzle outlet is 3mmφ locations apart 5mm the fluorescent screen was baked 45 minutes phosphor coating further 880 ° C. After 5 minutes baking at 620 ° C., the air pressure of 1.2 kg / cm ² 0.5 The diameter of the phosphor layer blown out for a second is measured. Therefore, the smaller the diameter, the greater the adhesive force. In this embodiment, the adhesive strength is 50 mmφ, and the initial light flux is 6,195 lumens. Next, after storing the binder slurry obtained in this example for 4 days, a fluorescent lamp was prepared, and the adhesive force and the initial luminous flux were measured in the same manner. The adhesive force was unchanged at 50 mmφ, and the initial luminous flux was 6194 lumens. And almost no difference. Similar results can be obtained in other embodiments.
[0022]
[Table 1]

[0023]
Also, when the average diameter of the peeled portion of the phosphor layer generated when the outer surface of the fluorescent lamp is impacted with a piano wire having a load of 300 g is measured, the phosphor layer of this embodiment and the other embodiments is measured. No dropout is seen.
[0024]
[Example 2]
Except that the firing temperature is set to 600 ° C., the same procedure as in Example 1 is performed to obtain a strontium borate having an average particle size of 0.5 μm and a binder slurry having a center particle size of 0.5 μm.
[0025]
[Example 3]
Except that the firing temperature is 900 ° C., the same procedure as in Example 1 is performed to obtain a strontium borate having an average particle size of 5.0 μm and a binder slurry having a center particle size of 1.5 μm.
[0026]
【The invention's effect】
As described above, when the binder of the present invention is used, the adhesive strength of the phosphor can be increased, there is no discoloration after baking, and the change with time can be reduced. The adhesive strength between the phosphor and the glass tube can be greatly improved, and a fluorescent lamp excellent in lamp luminous flux can be stably manufactured. In addition, the yield of the manufacturing process can be improved.

Claims

A strontium borate having an average particle size in a range of 0.5 to 5.0 μm, which is used for bonding a glass tube of a fluorescent lamp to a phosphor.

The strontium borate is obtained by calcining a precipitate formed by adjusting the pH of an aqueous solution containing a water-soluble strontium salt, boric acid and a base to a range of 7.5 to 10 at a temperature range of 600 to 900 ° C. The binder according to claim 1, wherein the binder is used.

A binder slurry obtained by using the binder according to claim 1, wherein the slurry has a center particle size of 2.0 μm or less.

A fluorescent lamp using the binder according to claim 1.

3. A fluorescent lamp, characterized in that the phosphor layer of the fluorescent lamp contains the binder according to claim 1 or 6% by weight or less based on the phosphor.

3. A fluorescent lamp, characterized in that the phosphor layer of the fluorescent lamp contains the binder according to claim 1 or 2 and particulate alumina, and the sum of the binder and the phosphor is 6% by weight or less based on the phosphor.

7. The fluorescent lamp according to claim 4, wherein the fluorescent lamp is a ring-shaped fluorescent lamp.