JP4756430B2 - Glass for electric lamp and manufacturing method thereof - Google Patents
Glass for electric lamp and manufacturing method thereof Download PDFInfo
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- JP4756430B2 JP4756430B2 JP2001105815A JP2001105815A JP4756430B2 JP 4756430 B2 JP4756430 B2 JP 4756430B2 JP 2001105815 A JP2001105815 A JP 2001105815A JP 2001105815 A JP2001105815 A JP 2001105815A JP 4756430 B2 JP4756430 B2 JP 4756430B2
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- 239000011521 glass Substances 0.000 title claims description 61
- 238000004519 manufacturing process Methods 0.000 title claims description 6
- 238000002834 transmittance Methods 0.000 claims description 28
- 239000011734 sodium Substances 0.000 claims description 14
- 229910018068 Li 2 O Inorganic materials 0.000 claims description 12
- 238000010521 absorption reaction Methods 0.000 claims description 12
- 229910004298 SiO 2 Inorganic materials 0.000 claims description 9
- 238000002844 melting Methods 0.000 claims description 8
- 230000008018 melting Effects 0.000 claims description 8
- 229910052708 sodium Inorganic materials 0.000 claims description 8
- 229910018072 Al 2 O 3 Inorganic materials 0.000 claims description 7
- 239000000203 mixture Substances 0.000 claims description 7
- 239000007800 oxidant agent Substances 0.000 claims description 7
- 230000001590 oxidative effect Effects 0.000 claims description 6
- VWDWKYIASSYTQR-UHFFFAOYSA-N sodium nitrate Chemical compound [Na+].[O-][N+]([O-])=O VWDWKYIASSYTQR-UHFFFAOYSA-N 0.000 claims description 6
- FGIUAXJPYTZDNR-UHFFFAOYSA-N potassium nitrate Chemical compound [K+].[O-][N+]([O-])=O FGIUAXJPYTZDNR-UHFFFAOYSA-N 0.000 claims description 4
- 235000010344 sodium nitrate Nutrition 0.000 claims description 3
- 239000004317 sodium nitrate Substances 0.000 claims description 3
- 235000010333 potassium nitrate Nutrition 0.000 claims description 2
- 239000004323 potassium nitrate Substances 0.000 claims description 2
- 238000004040 coloring Methods 0.000 description 19
- 239000002994 raw material Substances 0.000 description 19
- 230000000694 effects Effects 0.000 description 14
- 239000000126 substance Substances 0.000 description 9
- 238000004031 devitrification Methods 0.000 description 6
- 239000003513 alkali Substances 0.000 description 5
- 229910000287 alkaline earth metal oxide Inorganic materials 0.000 description 5
- 230000007423 decrease Effects 0.000 description 5
- 229910000272 alkali metal oxide Inorganic materials 0.000 description 4
- 238000010292 electrical insulation Methods 0.000 description 4
- WABPQHHGFIMREM-UHFFFAOYSA-N lead(0) Chemical compound [Pb] WABPQHHGFIMREM-UHFFFAOYSA-N 0.000 description 4
- 238000000034 method Methods 0.000 description 4
- BASFCYQUMIYNBI-UHFFFAOYSA-N platinum Chemical compound [Pt] BASFCYQUMIYNBI-UHFFFAOYSA-N 0.000 description 4
- 238000007496 glass forming Methods 0.000 description 3
- 239000012535 impurity Substances 0.000 description 3
- 238000002156 mixing Methods 0.000 description 3
- 238000000465 moulding Methods 0.000 description 3
- 230000003287 optical effect Effects 0.000 description 3
- 229910000497 Amalgam Inorganic materials 0.000 description 2
- OAICVXFJPJFONN-UHFFFAOYSA-N Phosphorus Chemical compound [P] OAICVXFJPJFONN-UHFFFAOYSA-N 0.000 description 2
- FAPWRFPIFSIZLT-UHFFFAOYSA-M Sodium chloride Chemical compound [Na+].[Cl-] FAPWRFPIFSIZLT-UHFFFAOYSA-M 0.000 description 2
- 229910004116 SrO 2 Inorganic materials 0.000 description 2
- 238000000137 annealing Methods 0.000 description 2
- 230000008859 change Effects 0.000 description 2
- 239000007795 chemical reaction product Substances 0.000 description 2
- 230000000052 comparative effect Effects 0.000 description 2
- 230000006866 deterioration Effects 0.000 description 2
- 238000010828 elution Methods 0.000 description 2
- 230000001747 exhibiting effect Effects 0.000 description 2
- 238000002474 experimental method Methods 0.000 description 2
- 239000000383 hazardous chemical Substances 0.000 description 2
- 150000002500 ions Chemical class 0.000 description 2
- 238000005259 measurement Methods 0.000 description 2
- 230000035699 permeability Effects 0.000 description 2
- 229910052697 platinum Inorganic materials 0.000 description 2
- 238000005498 polishing Methods 0.000 description 2
- 238000012545 processing Methods 0.000 description 2
- 239000000047 product Substances 0.000 description 2
- 239000011347 resin Substances 0.000 description 2
- 229920005989 resin Polymers 0.000 description 2
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 1
- 229910017493 Nd 2 O 3 Inorganic materials 0.000 description 1
- 229910000629 Rh alloy Inorganic materials 0.000 description 1
- PMZURENOXWZQFD-UHFFFAOYSA-L Sodium Sulfate Chemical compound [Na+].[Na+].[O-]S([O-])(=O)=O PMZURENOXWZQFD-UHFFFAOYSA-L 0.000 description 1
- QAOWNCQODCNURD-UHFFFAOYSA-L Sulfate Chemical compound [O-]S([O-])(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-L 0.000 description 1
- 229910010413 TiO 2 Inorganic materials 0.000 description 1
- 230000009471 action Effects 0.000 description 1
- 229910052783 alkali metal Inorganic materials 0.000 description 1
- 150000001340 alkali metals Chemical class 0.000 description 1
- 230000005540 biological transmission Effects 0.000 description 1
- 239000011449 brick Substances 0.000 description 1
- 229910052799 carbon Inorganic materials 0.000 description 1
- 229910000420 cerium oxide Inorganic materials 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- 238000002485 combustion reaction Methods 0.000 description 1
- 238000001816 cooling Methods 0.000 description 1
- 230000002950 deficient Effects 0.000 description 1
- 230000002542 deteriorative effect Effects 0.000 description 1
- 238000004090 dissolution Methods 0.000 description 1
- 239000010459 dolomite Substances 0.000 description 1
- 229910000514 dolomite Inorganic materials 0.000 description 1
- 238000010891 electric arc Methods 0.000 description 1
- 230000007613 environmental effect Effects 0.000 description 1
- 238000011156 evaluation Methods 0.000 description 1
- 239000000835 fiber Substances 0.000 description 1
- 239000006025 fining agent Substances 0.000 description 1
- 238000011835 investigation Methods 0.000 description 1
- 230000001678 irradiating effect Effects 0.000 description 1
- 229910000953 kanthal Inorganic materials 0.000 description 1
- 239000004973 liquid crystal related substance Substances 0.000 description 1
- QSHDDOUJBYECFT-UHFFFAOYSA-N mercury Chemical compound [Hg] QSHDDOUJBYECFT-UHFFFAOYSA-N 0.000 description 1
- 229910052753 mercury Inorganic materials 0.000 description 1
- 239000010446 mirabilite Substances 0.000 description 1
- 239000006060 molten glass Substances 0.000 description 1
- BMMGVYCKOGBVEV-UHFFFAOYSA-N oxo(oxoceriooxy)cerium Chemical compound [Ce]=O.O=[Ce]=O BMMGVYCKOGBVEV-UHFFFAOYSA-N 0.000 description 1
- PXXKQOPKNFECSZ-UHFFFAOYSA-N platinum rhodium Chemical compound [Rh].[Pt] PXXKQOPKNFECSZ-UHFFFAOYSA-N 0.000 description 1
- 230000005855 radiation Effects 0.000 description 1
- 229910001404 rare earth metal oxide Inorganic materials 0.000 description 1
- 230000009257 reactivity Effects 0.000 description 1
- 239000004576 sand Substances 0.000 description 1
- 239000011780 sodium chloride Substances 0.000 description 1
- 238000001228 spectrum Methods 0.000 description 1
- 238000003756 stirring Methods 0.000 description 1
- 230000007847 structural defect Effects 0.000 description 1
Images
Classifications
-
- C—CHEMISTRY; METALLURGY
- C03—GLASS; MINERAL OR SLAG WOOL
- C03C—CHEMICAL COMPOSITION OF GLASSES, GLAZES OR VITREOUS ENAMELS; SURFACE TREATMENT OF GLASS; SURFACE TREATMENT OF FIBRES OR FILAMENTS MADE FROM GLASS, MINERALS OR SLAGS; JOINING GLASS TO GLASS OR OTHER MATERIALS
- C03C3/00—Glass compositions
- C03C3/04—Glass compositions containing silica
- C03C3/076—Glass compositions containing silica with 40% to 90% silica, by weight
- C03C3/095—Glass compositions containing silica with 40% to 90% silica, by weight containing rare earths
-
- C—CHEMISTRY; METALLURGY
- C03—GLASS; MINERAL OR SLAG WOOL
- C03C—CHEMICAL COMPOSITION OF GLASSES, GLAZES OR VITREOUS ENAMELS; SURFACE TREATMENT OF GLASS; SURFACE TREATMENT OF FIBRES OR FILAMENTS MADE FROM GLASS, MINERALS OR SLAGS; JOINING GLASS TO GLASS OR OTHER MATERIALS
- C03C4/00—Compositions for glass with special properties
- C03C4/08—Compositions for glass with special properties for glass selectively absorbing radiation of specified wave lengths
- C03C4/085—Compositions for glass with special properties for glass selectively absorbing radiation of specified wave lengths for ultraviolet absorbing glass
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02B—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS
- Y02B20/00—Energy efficient lighting technologies, e.g. halogen lamps or gas discharge lamps
Description
【０００１】
【発明の属する技術分野】
本発明は蛍光ランプに用いられる電灯用ガラス組成物に関し、特にコンパクト型蛍光ランプに用いられる電灯用ガラス組成物に関するものである。
【０００２】
【従来の技術】
蛍光ランプは、アーク放電によって発生する紫外線で、ガラス管壁に塗布されている蛍光体を励起し、これにより発生する可視光線を利用したものである。
【０００３】
蛍光ランプに使用されるガラスは、管状のバルブ部とステム部に大別され、バルブ部の形状としては、直管や、直管を熱加工した環状の形状を有するものが一般的であるが、最近ではランプの効率化や小型化を目的に、Ｕ字管やこれを繋いだツイン管といった複雑な形状を有するコンパクト型蛍光灯が開発されている。当初、複雑な加工が必要なコンパクト型蛍光灯には、加工性のよい鉛含有ガラスが使用されていたが、鉛は環境負荷物質であるため、現在では無鉛ガラスへの代替が進められている。
【０００４】
【発明が解決しようとする課題】
ところで蛍光灯管内で発生した紫外線の一部は蛍光体膜を透過し、ガラス管に影響を与えることが知られている。特にコンパクト型蛍光灯では、通常の蛍光灯よりも高い電力が必要なため、単位面積当たりの紫外線照射量が数倍になる。その結果、紫外線エネルギーにより、有色イオンやガラス構造欠陥部の着色中心の生成によるガラスの着色が著しくなり、蛍光灯の輝度が経時的に劣化するという問題が生じる。また管外に漏洩する紫外線量が多くなり、蛍光ランプを保護する樹脂カバーを変色させてしまう。
【０００５】
本発明の目的は、紫外線による着色や管外への紫外線の漏洩がなく、しかも高輝度のコンパクト型蛍光ランプを作製することが可能な電灯用ガラスとその製造方法を提供することである。
【０００６】
【課題を解決するための手段】
本発明者は種々の実験を行った結果、ＣｅＯ2を添加するとともに、ＳＯ3の含有量を０．１８％以下に制限することにより、上記目的が達成できることを見いだし、本発明として提案するものである。
【０００７】
即ち、本発明の電灯用ガラスは、質量％表示で、ＳｉＯ２ ６０〜８０％、Ａｌ２Ｏ３ ０．５〜５％、Ｂ２Ｏ３ ０〜３％、Ｎａ２Ｏ ２〜１０％、Ｋ２Ｏ ２〜１０％、Ｌｉ２Ｏ ０．３〜３％、Ｎａ２Ｏ＋Ｋ２Ｏ＋Ｌｉ２Ｏ １３．２〜１８％、ＣａＯ ０〜８％、ＭｇＯ ０〜８％、ＳｒＯ ２〜１０％、ＢａＯ ２〜１２％、ＣａＯ＋ＭｇＯ＋ＳｒＯ＋ＢａＯ ５〜１５％、ＣｅＯ２ ０．２〜２％、ＳＯ３ ０〜０．１８％含有し、４００ｎｍにおける透過率が肉厚１ｍｍで９０．０％以上であることを特徴とする。
また本発明の電灯用ガラスの製造方法は、質量％表示で、ＳｉＯ ２ ６０〜８０％、Ａｌ ２ Ｏ ３ ０．５〜５％、Ｂ ２ Ｏ ３ ０〜３％、Ｎａ ２ Ｏ ２〜１０％、Ｋ ２ Ｏ ２〜１０％、Ｌｉ ２ Ｏ ０．３〜３％、Ｎａ ２ Ｏ＋Ｋ ２ Ｏ＋Ｌｉ ２ Ｏ １３．２〜１８％、ＣａＯ ０〜８％、ＭｇＯ ０〜８％、ＳｒＯ ２〜１０％、ＢａＯ ２〜１２％、ＣａＯ＋ＭｇＯ＋ＳｒＯ＋ＢａＯ ５〜１５％、ＣｅＯ ２ ０．２〜２％、ＳＯ ３ ０〜０．１８％含有する組成になるとともに酸化剤を含むようにバッチを調製した後、溶融することを特徴とする。
【０００８】
【発明の実施の形態】
本発明者は、ＣｅＯ2の紫外線遮蔽能力及び紫外線によるガラスの光学的劣化現象について詳細に調査したところ、ガラス中に含まれるＳＯ3について興味深い知見を得た。
【０００９】
一般に、ガラスに紫外線遮蔽能力を付与するにはＣｅＯ2を添加すればよいことが知られている。またＣｅＯ2の添加により、紫外線照射による着色が若干抑制される。一方、ＣｅＯ2を添加すると４００ｎｍ付近の光透過率が低下してガラスが黄色くなる、いわゆる初期着色が起こり易く、ランプの輝度が低下してしまう。従って、紫外線の管外への漏洩や紫外線による着色を防止しようとすると、ランプの輝度が低くなるという問題を有していた。
【００１０】
ところがＣｅＯ2を添加したガラスの透過率特性は、ＳＯ3の存在により大きく左右されることが本発明者の実験で明らかとなった。即ち、ＳＯ3の含有量を０．１８質量％以下に制限すると、４００ｎｍ付近の光透過率が高くなって初期着色が防止され、また紫外線照射による着色が著しく抑制される。このＳＯ3は、ガラス原料（芒硝（Ｎａ2ＳＯ4）等の硫酸塩原料や不純物）や、ガラス溶融時の燃焼雰囲気中のＳＯ2ガスの溶け込みにより、ガラス組成中に取り込まれる。
【００１１】
本発明の電灯用ガラスにおいて、ＣｅＯ2やＳＯ3の含有量は、上記知見をふまえて決定したものである。
【００１２】
ＣｅＯ2は、ガラスに紫外線遮蔽能力を付与するとともに、ＳＯ3が０．１８質量％以下という条件下で、紫外線照射による着色を著しく抑制する働きがある。また清澄剤としても機能する。ＣｅＯ2が０．２％以下ではその効果がなく、２％を超えると着色が著しくなり、高輝度のランプを得ることが困難になる。なおＣｅＯ2の好適な範囲は、０．３〜１．２％、特に０．４〜１％である。
【００１３】
ＳＯ3の含有量は０．１８質量％以下に制限される。ＳＯ3は、ＣｅＯ2によるガラスの着色を助長し、また紫外線着色を起こしやすい成分であり、その含有量は少ないほど好ましい。このため０．１５％以下、特に０．１％以下が好ましく、できれば含まないことが望ましい。
【００１４】
また、蛍光ランプ用途に要求される上記以外の特性としては以下のものが挙げられる。
▲１▼管内に封入される水銀ガスと反応してアマルガム（ＨｇＮａ）を生成しないように、高い化学耐久性が求められる。具体的には、ＪＩＳ Ｒ３５０２に示された方法で測定されるアルカリ溶出が０．７ｍｇ以下であること。
▲２▼ステム用として使われる場合、デュメットリード線と膨張が適合するように、９０〜１００×１０-7／℃の熱膨張係数を有すること。
▲３▼ステム用として使われる場合、体積抵抗が１０-7Ω・ｃｍ以上と高いこと。
▲４▼ガラス溶融が容易であること。
▲５▼コンパクト型蛍光ランプのバルブ用途の場合、高い加工性を得るために、作業点（１０4ポイズに相当する温度）が１０１０℃以下であること。
【００１５】
本発明のガラスにおいて、ＣｅＯ2やＳＯ3以外の成分の含有量は、これらの諸特性を満足するために上記範囲に特定される。
【００１６】
ＣｅＯ2、ＳＯ3以外の成分の組成範囲を上記のように限定した理由を以下に示す。
【００１７】
ＳｉＯ2はガラスの骨格を形成する成分である。ＳｉＯ2が６０％より少ないとガラス骨格の生成が不十分となり、機械的強度が低くなる。ＳｉＯ2が８０％より多いとガラスの粘性が上昇し、溶融成形が困難になる。ＳｉＯ2の好ましい範囲は６０〜７５％である。
【００１８】
Ａｌ2Ｏ3も骨格形成成分であり、また化学耐久性を向上させるとともに、ガラス成形時の失透を抑制する効果がある。Ａｌ2Ｏ3が０．５％より少ないとその効果がなく、５％より多いと溶融や成形が困難になる。Ａｌ2Ｏ3の好ましい範囲は１〜３％である。
【００１９】
Ｂ2Ｏ3は化学耐久性を改善し、高温粘性を低下させる効果がある。しかしＢ2Ｏ3は環境負荷物質であるため、やむを得ない場合を除き、使用しないことが望ましい。Ｂ2Ｏ3が３％より多い場合はガラス低温粘性が上昇し、加工性が悪化する。またＣｅＯ2の着色傾向を増大させてしまう。
【００２０】
Ｎａ2Ｏ、Ｋ2Ｏ、Ｌｉ2Ｏといったアルカリ金属酸化物は、熱膨張係数を調整し、またガラスの粘性を低下させて加工性を高めるための成分である。Ｎａ2Ｏ及びＫ2Ｏは特定の比率で共存させることにより、アルカリ混合効果とよばれる化学耐久性や電気絶縁性を向上させる効果が得られる。またＬｉ2Ｏは、原料コストが高く多量に含有させることは好ましくないが、膨張調整機能が他のアルカリ金属成分に比べて約２倍と高いため、少量の添加で効果がある。
【００２１】
Ｎａ2Ｏが２％未満の場合はその効果がなく、１０％を超える場合はアルカリ混合効果が得られず、化学耐久性が悪くなる。Ｎａ2Ｏの好ましい範囲は４〜８％である。
【００２２】
Ｋ2Ｏが２％未満の場合はその効果がなく、１０％を超える場合はアルカリ混合効果が得られず、化学耐久性が悪くなる。Ｋ2Ｏの好ましい範囲は４〜８％である。
【００２３】
Ｌｉ2Ｏが０．３％未満の場合、デュメットリード線との膨張の整合性を得ようとするとＮａ2ＯやＫ2Ｏを多量に含有させる必要が生じ、化学耐久性が悪化する。３％を超えると原料コストが高くなりすぎる。Ｌｉ2Ｏの好ましい範囲は０．５〜３％である。
【００２４】
アルカリ金属酸化物の合量が１３．２％未満では、ステム用途に用いた場合にデュメットリード線との膨張の整合性が得難くなる。またガラスの粘性が上昇し、加工性が悪化しやすくなる。またアルカリ金属酸化物の合量が１８％を超えるとステム用途に用いた場合にデュメットリード線との膨張の整合性が得難くなる。また化学耐久性が悪化し、輝度劣化の原因となるアマルガムの生成を起こし易くなる。なおアルカリ金属酸化物の合量の好ましい範囲は１３．５〜１８％である。
【００２５】
ＣａＯ、ＭｇＯ、ＳｒＯ、ＢａＯといったアルカリ土類金属酸化物は、高電気絶縁性と良好な加工性を得るための成分である。特に比較的ＰｂＯに近い性質を有するＳｒＯとＢａＯを主として使用する。しかしこれらの成分は、ガラス溶融時や管引き成形時に使用される耐火レンガとの反応性が強く、反応生成物の原因となる。こうした生成物の発生を避けたい場合には、これらの一部をＣａＯやＭｇＯと置換すればよい。ただしＣａＯは、ＣｅＯ2と共存させるとガラスの光透過率を低下させる傾向があるため、その添加は最小限に留めることが望ましい。
【００２６】
ＣａＯが８％を超えるとガラス成形時の失透原因となる。なおＣａＯを０．５％以下に制限することにより、より高い光透過率を得ることができる。
【００２７】
ＭｇＯが８％を超えるとガラス成形時の失透原因となり、またガラスの粘性を上昇させて加工性が悪化する。ＭｇＯの好ましい範囲は２〜６％である。
【００２８】
ＳｒＯが２％未満では、高電気絶縁性と良好な加工性を得るために他のアルカリ土類金属酸化物を多量に含有させなければならないが、これによって失透が起こり易くなる。１０％を超えるとＳｒＯ系の失透物が生じ、また原料コストが増大して好ましくない。ＳｒＯの好ましい範囲は４〜１０％、特に４．２〜８％である。
【００２９】
ＢａＯが２％未満では高電気絶縁性と良好な加工性を得るために他のアルカリ土類金属酸化物を多量に含有させなければならないが、これによって失透が起こり易くなる。１２％を超えると耐火物（Ａｌ系耐火物）との反応が著しく、失透原因となる。ＢａＯの好ましい範囲は３〜１０％である。
【００３０】
アルカリ土類金属酸化物の合量は５〜１５％である。これらの合量が５％未満では電気抵抗等、蛍光ランプ用途に必要な特性を得ることが難しくなる。一方１５％を超えるとガラスの成形時に失透物や反応生成物が生じ、製品不良を引き起こす可能性がある。アルカリ土類金属酸化物の合量の好ましい範囲は６〜１３％である。
【００３１】
以上の成分以外にも、例えば稀土類酸化物等の光透過特性を改善する成分や、ＴｉＯ2、ＺｒＯ2等の紫外線着色防止効果を有する成分の添加が可能である。また清澄剤として、ＮａＣｌ等のＣｌ系原料を添加してもよい。なお不純物として、Ｆｅ2Ｏ3が含まれることが多いが、Ｆｅは有色イオンであり、透過率を低下させる要因であるので、０．０５％以下、特に０．０３％以下に制限することが重要である。またＮｄ2Ｏ3のような可視光透過率を低下させる成分を含有すべきではない。さらに環境上の理由から、ＰｂＯやＡｓ2Ｏ3を含有することも避けるべきである。
【００３２】
上記組成を有する本発明のガラスは、紫外線照射後に（１）肉厚１ｍｍにおいて、ＪＩＳ Ｚ８７０１に規定するＸＹＺ表色系に基づくＹ値が９０．０％以上、及び（２）肉厚１ｍｍにおいて、４００ｎｍでの光透過率が８８．０％以上、という特性を満足することができる。これらの特性を満足することにより、輝度が高いランプを作製することができる。なお４００ｎｍでの光透過率は、９０．０％以上、特に９０．５％以上であることが好ましく、またＹ値は９１．０％以上、特に９１．５％以上であることが好ましい。なお本発明において、Ｙ値及び４００ｎｍでの光透過率は、３０倍視野の光学顕微鏡にて研磨傷が確認できない程度に光学研磨された３０×１０ｍｍ、肉厚１．０±０．０２ｍｍの試料に対し、２５６ｎｍに主波長を有する紫外線を７．５ｍｗ／ｃｍ2の照度で８時間照射した後に評価した値である。また４００ｎｍでの光透過率は、Ｃ標準光源を用い、分光光度計にて４００ｎｍにおける透過率を求めたものであり、Ｙ値は同様にして測定域２００〜８００ｎｍにおける透過率を求め、ＪＩＳ Ｚ８７０１に基づいて算出したものである。
【００３３】
なお上記特性に加えて、本発明のガラスは、紫外線の吸収端が３１４ｎｍ以上、特に３２０ｎｍ以上であることが好ましい。即ち、蛍光ランプから生じるスペクトルは、２５８ｎｍ付近に主ピークを持ち、他にいくつかの副線が存在する。この中でも最長の副線ピークは可視光域にまで及ぶ。一般的な電灯用ガラスでは、２５８ｎｍより長波長域の紫外線を十分に遮蔽することは難しいが、通常の蛍光ランプではこれらの副線が問題となることは殆どない。しかし、紫外線放射量が多いコンパクト型蛍光ランプでは、この長波長域の副線、特に３１３ｎｍ付近の副線によって樹脂カバーが変色し易くなる。それゆえ紫外線の吸収端が３１３ｎｍより長波長側にあることが望まれる。
【００３４】
また本発明の電灯用ガラスは、酸化性雰囲気で溶融することが望ましい。
【００３５】
即ち、本発明のガラスにおいて、重要な役割を有するＣｅＯ2は、ガラス中で
Ｃｅ3+ ⇔ Ｃｅ4+
の酸化還元平衡状態にある。一般にＣｅ3+は３１６ｎｍに、Ｃｅ4+は２４３ｎｍ付近にそれぞれ主たる吸収帯を有し、両者の働きにより長波長側の紫外線が吸収されガラスの紫外線吸収端が形成される。ここでＣｅ3+量が多くなると、紫外線の吸収端が長波長側へ移動したり、吸収帯幅が増加する。その結果、４００ｎｍ付近の可視域が吸収されてガラスが黄色味を帯び、透過率が低下する。これがＣｅＯ2による初期着色であり、高輝度の蛍光ランプを得ることできない原因となる。従ってＣｅ3+とＣｅ4+は適切な割合で存在させることが重要である。そこでガラスを酸化性雰囲気で溶融することにより、Ｃｅ4+を増加させ、４００ｎｍ付近の可視域の吸収を抑え、初期着色を防止することができる。
【００３６】
なお酸化性雰囲気で溶融する方法としては、例えばガラス原料バッチに酸化剤（例えば硝酸ナトリウムや硝酸カリウム）を加え、ガラス溶融時にガラスが酸化状態になるようにすればよい。酸化剤のバッチへの添加量は、使用する酸化剤の種類にもよるが、０．５〜３質量％程度が好ましい。その理由は、０．５％以下では十分な効果が得られず、３％を超えて添加しても原料コストが上昇するのみで、その効果は殆ど変わらないためである。
【００３７】
【実施例】
以下、実施例に基づいて本発明を説明する。
【００３８】
（実施例１）
表１、２は、ＣｅＯ2とＳＯ3を変更し、紫外線照射前後の透過率を評価した本発明の実施例（試料Ｎｏ．１〜４）及び比較例（Ｎｏ．５〜７）である。また紫外線着色に対するＣｅＯ2とＳＯ3の関係を図１に示す。
【００３９】
【表１】
【表２】
各試料は次のようにして調製した。
【００４２】
まず表に示す組成となるようにガラス原料を調合した。さらに調合した原料をライカイ機と呼ばれる乳鉢式擂り潰し攪拌機で１０分間攪拌し、３００ｇの原料バッチを得た。なお使用した原料は、ＳｉＯ2原料として比較的Ｆｅ不純物が少ない海岸砂（ＳｉＯ2分９９．８質量％）を、ＭｇＯ原料及びＣａＯ原料として市販ドロマイトを、ＣｅＯ2原料としてガラス工業用酸化セリウム（ＣｅＯ2分９９．８％以上）を、その他の酸化物原料は、主として量産に適した一般的に使用されるもののうち、できる限り安価な工業用ガラス原料を使用した。また酸化剤には硝酸ナトリウムを使用した。
【００４３】
次に原料バッチを容量３００ｃｍ3の白金ロジウム合金製の坩堝に入れ、箱型電気炉にて１４５０〜１５００℃で４時間溶融した。なお溶融開始後３０分毎に白金攪拌棒を用いて計３回攪拌を行った。
【００４４】
続いて溶融ガラスをカーボン製成形板上に流し出し、５６０℃に保持された箱型カンタル式アニール炉内に入れ、４℃／分の平均冷却速度で炉冷した。さらにアニール後のガラス塊から試料を作製し、評価に共した。結果を表１，２に示す。併せて紫外線照射前後のＹ値の変化を図１に示す。
【００４５】
その結果、ＳＯ3を０．２％含有する試料Ｎｏ．５〜７は、初期のＹ値が低く、また紫外線照射によるＹ値低下が大きかった。これに対してＳＯ3を含まない試料Ｎｏ．１〜４は、初期のＹ値が高く、しかもＹ値の低下が殆どないことが分かった。つまりＳＯ3を少なくすれば、透過率が高く、しかも紫外線着色が起こり難いガラスが得られることを示している。
【００４６】
またＮｏ．５〜７の試料は、ＣｅＯ2量が増えるに従い初期のＹ値が低下する傾向にあるが、実施例であるＮｏ．１〜４の試料では、ＣｅＯ2量が増えても初期Ｙ値が殆ど変化しない。このことは、ガラスの紫外線吸収能力を高めるためにＣｅＯ2を多量に添加できることを示唆している。
【００４７】
なお熱膨張係数は、３０〜３８０℃における平均線熱膨張係数を示すものであり、ディラトメーターを用いて測定した。軟化点は１０7.6ｄＰａ・ｓの粘度を示す温度、作業点は１０4ｄＰａ・ｓの粘度を示す温度であり、それぞれＡＳＴＭで規定されるファイバー引っ張り法、及び白金球引き上げ法を用いて求めた。体積電気抵抗値は、ＡＳＴＭ Ｃ６５７−７８に基づき測定し、２５０℃での抵抗値を対数表示した。アルカリ溶出量は、ＪＩＳ Ｒ−３５０２に基づいて測定したものである。
【００４８】
Ｙ値、４００ｎｍでの光透過率及び紫外線吸収端は、次のようにして求めた。まず３０倍視野の光学顕微鏡にて研磨傷が確認できない程度に光学研磨された３０×１０ｍｍ、肉厚１．０±０．０２ｍｍの試料を用意した。次にＣ標準光源を用い、分光光度計（島津製作所製ＵＶ３１００ＰＣ）にて２００〜８００ｎｍにおける透過率を測定し、４００ｎｍでの透過率及び紫外線吸収端を求めた。なお紫外線吸収端は、光透過率曲線の短波長側で実質的に透過率が０％と見なし得る波長とした。さらに透過率測定データから、ＪＩＳ Ｚ８７０１に規定するＸＺＹ表色系に基づいてＹ値を算出した。続いて、ＵＶドライプロセッサー（オーク製作所製）を用い、２５６ｎｍに主波長を有する紫外線を試料に７．５ｍｗ／ｃｍ2の照度で８時間照射した後、再度透過率を測定し、紫外線照射後のＹ値及び４００ｎｍにおける透過率を求めた。
（実施例２）
表３〜７は本発明の他の実施例（試料Ｎｏ．８〜２７）を、表８は比較例（試料Ｎｏ．２８）をそれぞれ示している。
【００４９】
なお各試料は、実施例１に準じて調製し、評価した。
【００５０】
【表３】
【表４】
【表５】
【表６】
【表７】
【表８】
表から、本発明の実施例である試料Ｎｏ．８〜２７は、紫外線照射後のＹ値及び４００ｎｍでの光透過率が、それぞれ９０．９％以上、８８．７％以上であり、紫外線照射後も高い透過率を維持していた。
【００５７】
【発明の効果】
以上説明したように、本発明の電灯用ガラスは、紫外線による着色や管外への紫外線の漏洩がなく、しかも高輝度のコンパクト型蛍光ランプを作製することが可能であり、電灯用ガラスとして好適である。なお本明細書においては、主としてコンパクト型蛍光ランプのバルブ用ガラスについて説明したが、本発明のガラスはこれに限られるものではなく、他のランプ用途（液晶ディスプレーに用いられるバックライトの蛍光ランプ用バルブ等）や、他の照明用部材（ステム、排気管等）に使用してもよい。
【図面の簡単な説明】
【図１】紫外線照射前後のＹ値の変化を示すグラフである。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a glass composition for electric lamps used for fluorescent lamps, and more particularly to a glass composition for electric lamps used for compact fluorescent lamps.
[0002]
[Prior art]
The fluorescent lamp uses ultraviolet rays generated by arc discharge to excite the phosphor applied to the glass tube wall and uses visible light generated thereby.
[0003]
Glass used for fluorescent lamps is broadly divided into a tubular bulb part and a stem part, and the bulb part is generally a straight pipe or an annular shape obtained by thermally processing a straight pipe. Recently, compact fluorescent lamps having a complicated shape such as a U-shaped tube and a twin tube connected to the tube have been developed for the purpose of improving the efficiency and miniaturization of the lamp. At first, compact fluorescent lamps that required complicated processing used lead-containing glass with good processability, but because lead is an environmentally hazardous substance, it is now being replaced with lead-free glass. .
[0004]
[Problems to be solved by the invention]
By the way, it is known that a part of ultraviolet rays generated in the fluorescent lamp tube passes through the phosphor film and affects the glass tube. In particular, since compact fluorescent lamps require higher power than ordinary fluorescent lamps, the amount of ultraviolet irradiation per unit area is several times greater. As a result, there is a problem that due to ultraviolet energy, coloring of the glass due to the generation of colored ions and coloring centers of glass structural defect portions becomes remarkable, and the luminance of the fluorescent lamp deteriorates with time. Moreover, the amount of ultraviolet rays leaking out of the tube increases, and the resin cover protecting the fluorescent lamp is discolored.
[0005]
An object of the present invention is to provide a glass for an electric lamp capable of producing a high-intensity compact fluorescent lamp without coloring due to ultraviolet rays or leakage of ultraviolet rays to the outside of the tube, and a method for producing the same.
[0006]
[Means for Solving the Problems]
As a result of various experiments, the present inventor has found that the above object can be achieved by adding CeO 2 and limiting the content of SO 3 to 0.18% or less, and proposes the present invention. It is.
[0007]
That is, the glass for electric lamps of the present invention is represented by mass%, SiO 2 60-80%, Al 2 O 3 0.5-5%, B 2 O 3 0-3%, Na 2 O 2-10%, K 2 O 2~10%, Li 2 O 0.3~3%, Na 2 O + K 2 O + Li 2 O 13.2~18%,
The manufacturing method of the lamp glass of the present invention is represented by mass%, SiO 2 60~80%, Al 2 O 3 0.5~5%, B 2 O 3 0~3%, Na 2 O 2~10 %, K 2 O 2~10%, Li 2 O 0.3~3%, Na 2 O + K 2 O + Li 2 O 13.2~18%,
[0008]
DETAILED DESCRIPTION OF THE INVENTION
The inventor conducted detailed investigations on the ultraviolet shielding ability of CeO 2 and the optical deterioration phenomenon of the glass due to the ultraviolet rays. As a result, the inventor obtained interesting knowledge about SO 3 contained in the glass.
[0009]
In general, it is known that CeO 2 may be added to impart an ultraviolet shielding ability to glass. Further, the addition of CeO 2 slightly suppresses coloring due to ultraviolet irradiation. On the other hand, when CeO 2 is added, the light transmittance in the vicinity of 400 nm is lowered and the glass becomes yellow, so-called initial coloring easily occurs, and the luminance of the lamp is lowered. Accordingly, when trying to prevent leakage of ultraviolet rays to the outside of the tube or coloring due to ultraviolet rays, there is a problem that the luminance of the lamp is lowered.
[0010]
However, the inventors' experiments have revealed that the transmittance characteristics of the glass to which CeO 2 is added are greatly influenced by the presence of SO 3 . That is, when the SO 3 content is limited to 0.18% by mass or less, the light transmittance near 400 nm is increased to prevent initial coloring, and coloring due to ultraviolet irradiation is remarkably suppressed. This SO 3 is incorporated into the glass composition by the dissolution of the glass raw material (sulfate raw material such as mirabilite (Na 2 SO 4 ) and impurities) and SO 2 gas in the combustion atmosphere at the time of glass melting.
[0011]
In the glass for electric lamps of the present invention, the contents of CeO 2 and SO 3 are determined based on the above knowledge.
[0012]
CeO 2 has the function of remarkably suppressing coloring due to ultraviolet irradiation under the condition that the glass has an ultraviolet shielding ability and SO 3 is 0.18% by mass or less. Also functions as a fining agent. If the CeO 2 content is 0.2% or less, the effect is not obtained. If the CeO 2 content exceeds 2%, the coloring becomes remarkable, and it becomes difficult to obtain a high-intensity lamp. A preferable range of CeO 2 is 0.3 to 1.2%, particularly 0.4 to 1%.
[0013]
The SO 3 content is limited to 0.18% by mass or less. SO 3 is a component that promotes coloring of the glass with CeO 2 and easily causes ultraviolet coloring, and the smaller the content thereof, the more preferable. For this reason, 0.15% or less, especially 0.1% or less is preferable, and it is desirable not to include it if possible.
[0014]
Moreover, the following are mentioned as characteristics other than the above required for fluorescent lamp applications.
(1) High chemical durability is required so that it does not react with mercury gas sealed in the tube to produce amalgam (HgNa). Specifically, the alkali elution measured by the method shown in JIS R3502 is 0.7 mg or less.
(2) When used as a stem, it should have a coefficient of thermal expansion of 90 to 100 × 10 −7 / ° C. so that the expansion meets the dumet lead wire.
(3) When used as a stem, the volume resistance should be as high as 10 −7 Ω · cm or higher.
(4) Glass melting is easy.
(5) In the case of a compact fluorescent lamp bulb, the working point (temperature corresponding to 10 4 poise) should be 1010 ° C. or lower in order to obtain high workability.
[0015]
In the glass of the present invention, the content of components other than CeO 2 and SO 3 is specified in the above range in order to satisfy these various characteristics.
[0016]
The reason why the composition range of components other than CeO 2 and SO 3 is limited as described above will be described below.
[0017]
SiO 2 is a component that forms a glass skeleton. If the SiO 2 content is less than 60%, the generation of the glass skeleton is insufficient and the mechanical strength is lowered. If the SiO 2 content is more than 80%, the viscosity of the glass increases, and melt molding becomes difficult. The preferred range of SiO 2 is 60 to 75%.
[0018]
Al 2 O 3 is also a skeleton-forming component and has the effect of improving chemical durability and suppressing devitrification during glass forming. If Al 2 O 3 is less than 0.5%, the effect is not obtained, and if it is more than 5%, melting or molding becomes difficult. A preferred range for Al 2 O 3 is 1-3%.
[0019]
B 2 O 3 has the effect of improving the chemical durability and lowering the high temperature viscosity. However, since B 2 O 3 is an environmentally hazardous substance, it is desirable not to use it unless it is unavoidable. When B 2 O 3 is more than 3%, the low-temperature viscosity of the glass increases and the workability deteriorates. Moreover, the coloring tendency of CeO 2 is increased.
[0020]
Alkali metal oxides such as Na 2 O, K 2 O, and Li 2 O are components for adjusting the coefficient of thermal expansion and reducing the viscosity of the glass to improve workability. By causing Na 2 O and K 2 O to coexist at a specific ratio, an effect of improving chemical durability and electrical insulation, called an alkali mixing effect, can be obtained. Li 2 O has a high raw material cost and is not preferable to be contained in a large amount. However, since the expansion adjustment function is about twice as high as that of other alkali metal components, addition of a small amount is effective.
[0021]
When Na 2 O is less than 2%, the effect is not obtained, and when it exceeds 10%, the alkali mixing effect cannot be obtained and the chemical durability is deteriorated. A preferred range for Na 2 O is 4-8%.
[0022]
When K 2 O is less than 2%, the effect is not obtained, and when it exceeds 10%, the alkali mixing effect cannot be obtained and the chemical durability is deteriorated. A preferred range for K 2 O is 4-8%.
[0023]
When Li 2 O is less than 0.3%, it is necessary to contain a large amount of Na 2 O or K 2 O in order to obtain expansion consistency with the dumet lead wire, and chemical durability is deteriorated. If it exceeds 3%, the raw material cost becomes too high. A preferable range of Li 2 O is 0.5 to 3%.
[0024]
If the total amount of the alkali metal oxide is less than 13.2%, it is difficult to obtain expansion consistency with the dumet lead wire when used for a stem application. In addition, the viscosity of the glass increases, and the processability tends to deteriorate. On the other hand, if the total amount of the alkali metal oxide exceeds 18%, it is difficult to obtain expansion consistency with the dumet lead wire when used for a stem application. Further, the chemical durability is deteriorated, and it is easy to generate amalgam that causes luminance deterioration. In addition, the preferable range of the total amount of alkali metal oxide is 13.5 to 18%.
[0025]
Alkaline earth metal oxides such as CaO, MgO, SrO and BaO are components for obtaining high electrical insulation and good workability. In particular, SrO and BaO having properties relatively close to PbO are mainly used. However, these components have a strong reactivity with refractory bricks used at the time of glass melting and pipe drawing, and cause reaction products. In order to avoid the generation of such products, a part of them may be replaced with CaO or MgO. However, CaO tends to lower the light transmittance of the glass when it coexists with CeO 2 , so addition of CaO is desirably kept to a minimum.
[0026]
When CaO exceeds 8%, it causes devitrification at the time of glass forming. A higher light transmittance can be obtained by limiting CaO to 0.5% or less.
[0027]
When MgO exceeds 8%, it causes devitrification at the time of glass forming, and also increases the viscosity of the glass, thereby deteriorating workability. The preferred range for MgO is 2-6%.
[0028]
If SrO is less than 2%, a large amount of other alkaline earth metal oxides must be contained in order to obtain high electrical insulation and good workability, but this tends to cause devitrification. If it exceeds 10%, SrO-based devitrified matter is generated, and the raw material cost increases, which is not preferable. The preferable range of SrO is 4 to 10%, particularly 4.2 to 8%.
[0029]
If BaO is less than 2%, a large amount of other alkaline earth metal oxides must be contained in order to obtain high electrical insulation and good processability, but this tends to cause devitrification. If it exceeds 12%, the reaction with the refractory (Al-based refractory) becomes remarkable, causing devitrification. The preferable range of BaO is 3 to 10%.
[0030]
The total amount of alkaline earth metal oxide is 5-15%. If the total amount is less than 5%, it is difficult to obtain characteristics required for fluorescent lamp applications such as electrical resistance. On the other hand, if it exceeds 15%, a devitrified substance and a reaction product are produced at the time of molding the glass, which may cause defective products. The preferable range of the total amount of the alkaline earth metal oxide is 6 to 13%.
[0031]
In addition to the above components, it is possible to add components that improve light transmission characteristics such as rare earth oxides and components that have an effect of preventing ultraviolet coloring such as TiO 2 and ZrO 2 . Moreover, you may add Cl type raw materials, such as NaCl, as a clarifier. In many cases, Fe 2 O 3 is contained as an impurity. However, since Fe is a colored ion and causes a decrease in transmittance, it may be limited to 0.05% or less, particularly 0.03% or less. is important. In addition, it should not contain a component that lowers the visible light transmittance such as Nd 2 O 3 . Furthermore, for environmental reasons, the inclusion of PbO or As 2 O 3 should be avoided.
[0032]
The glass of the present invention having the above composition has a Y value of 90.0% or more based on the XYZ color system defined in JIS Z8701 at (1) thickness 1 mm after ultraviolet irradiation, and (2) at thickness 1 mm. The characteristic that the light transmittance at 400 nm is 88.0% or more can be satisfied. By satisfying these characteristics, a lamp with high luminance can be manufactured. The light transmittance at 400 nm is preferably 90.0% or more, particularly preferably 90.5% or more, and the Y value is preferably 91.0% or more, particularly preferably 91.5% or more. In the present invention, the Y value and the light transmittance at 400 nm are 30 × 10 mm and a sample having a thickness of 1.0 ± 0.02 mm optically polished to such an extent that polishing scratches cannot be confirmed with an optical microscope with a 30 × field of view. On the other hand, it is a value evaluated after irradiating ultraviolet rays having a dominant wavelength at 256 nm with an illuminance of 7.5 mw / cm 2 for 8 hours. The light transmittance at 400 nm was obtained by measuring the transmittance at 400 nm with a spectrophotometer using a C standard light source, and the Y value was similarly determined for the transmittance in the measurement range of 200 to 800 nm. JIS Z8701 Is calculated based on
[0033]
In addition to the above characteristics, the glass of the present invention preferably has an ultraviolet absorption edge of 314 nm or more, particularly 320 nm or more. That is, the spectrum generated from the fluorescent lamp has a main peak in the vicinity of 258 nm, and some other sub-lines exist. Among these, the longest subline peak extends to the visible light region. In general glass for electric lamps, it is difficult to sufficiently shield ultraviolet rays having a wavelength longer than 258 nm. However, in a normal fluorescent lamp, these sub-lines hardly pose a problem. However, in a compact fluorescent lamp with a large amount of ultraviolet radiation, the resin cover is easily discolored by this long wavelength sub-line, particularly a sub-line near 313 nm. Therefore, it is desirable that the absorption edge of ultraviolet rays be on the longer wavelength side than 313 nm.
[0034]
The glass for electric lamps of the present invention is desirably melted in an oxidizing atmosphere.
[0035]
That is, CeO 2 having an important role in the glass of the present invention is Ce 3+ ⇔ Ce 4+ in the glass.
It is in a redox equilibrium state. In general, Ce 3+ has a main absorption band at 316 nm and Ce 4+ has a main absorption band near 243 nm, respectively, and ultraviolet rays on the long wavelength side are absorbed by the action of both, and an ultraviolet absorption edge of glass is formed. Here, when the amount of Ce 3+ increases, the absorption edge of ultraviolet rays moves to the longer wavelength side, or the absorption band width increases. As a result, the visible region near 400 nm is absorbed, the glass becomes yellowish, and the transmittance decreases. This is the initial coloring with CeO 2 , which causes a high-intensity fluorescent lamp not to be obtained. Therefore, it is important that Ce 3+ and Ce 4+ are present in an appropriate ratio. Therefore, by melting the glass in an oxidizing atmosphere, Ce 4+ can be increased, absorption in the visible region near 400 nm can be suppressed, and initial coloring can be prevented.
[0036]
As a method for melting in an oxidizing atmosphere, for example, an oxidizing agent (for example, sodium nitrate or potassium nitrate) may be added to a glass raw material batch so that the glass is in an oxidized state when the glass is melted. The amount of the oxidant added to the batch is preferably about 0.5 to 3% by mass, although it depends on the type of oxidant used. The reason is that if 0.5% or less, a sufficient effect cannot be obtained, and adding over 3% only raises the raw material cost, and the effect is almost unchanged.
[0037]
【Example】
Hereinafter, the present invention will be described based on examples.
[0038]
Example 1
Tables 1 and 2 show examples (samples No. 1 to 4) and comparative examples (Nos. 5 to 7) of the present invention in which CeO 2 and SO 3 were changed and transmittance before and after ultraviolet irradiation was evaluated. FIG. 1 shows the relationship between CeO 2 and SO 3 with respect to ultraviolet coloring.
[0039]
[Table 1]
[Table 2]
Each sample was prepared as follows.
[0042]
First, glass raw materials were prepared so as to have the composition shown in the table. Furthermore, the prepared raw material was stirred for 10 minutes with a mortar-type crushing stirrer called “Laikai machine” to obtain a 300 g raw material batch. The raw materials used were coastal sand (SiO 2 min 99.8% by mass) with relatively few Fe impurities as the SiO 2 raw material, commercially available dolomite as the MgO raw material and CaO raw material, and cerium oxide for the glass industry as the CeO 2 raw material ( the CeO 2 minutes 99.8% or higher), others oxides raw material, among those commonly employed which are suitable for mainly mass production, using less expensive industrial glass raw material as possible. Further, sodium nitrate was used as the oxidizing agent.
[0043]
Next, the raw material batch was put into a crucible made of platinum rhodium alloy having a capacity of 300 cm 3 and melted at 1450 to 1500 ° C. for 4 hours in a box-type electric furnace. In addition, it stirred for a total of 3 times using the platinum stirring rod every 30 minutes after the melting start.
[0044]
Subsequently, the molten glass was poured onto a carbon molded plate, placed in a box-type Kanthal annealing furnace maintained at 560 ° C., and cooled at an average cooling rate of 4 ° C./min. Further, a sample was prepared from the glass lump after annealing and used for evaluation. The results are shown in Tables 1 and 2. In addition, the change in the Y value before and after the ultraviolet irradiation is shown in FIG.
[0045]
As a result, sample No. containing 0.2% SO 3 was obtained. Nos. 5 to 7 had a low initial Y value and a large decrease in the Y value due to ultraviolet irradiation. Sample No. without the SO 3 contrast 1-4 were found to have a high initial Y value and almost no decrease in the Y value. In other words, it is shown that if SO 3 is reduced, a glass having high transmittance and hardly causing ultraviolet coloring can be obtained.
[0046]
No. In the samples Nos. 5 to 7, the initial Y value tends to decrease as the CeO 2 amount increases. In the samples 1 to 4, the initial Y value hardly changes even when the amount of CeO 2 increases. This suggests that a large amount of CeO 2 can be added to increase the ultraviolet absorbing ability of the glass.
[0047]
The thermal expansion coefficient indicates an average linear thermal expansion coefficient at 30 to 380 ° C., and was measured using a dilatometer. The softening point is a temperature exhibiting a viscosity of 10 7.6 dPa · s, and the working point is a temperature exhibiting a viscosity of 10 4 dPa · s, which were determined using the fiber pulling method and the platinum ball pulling method defined by ASTM, respectively. . The volume electric resistance value was measured based on ASTM C657-78, and the resistance value at 250 ° C. was expressed logarithmically. The alkali elution amount is measured based on JIS R-3502.
[0048]
The Y value, the light transmittance at 400 nm, and the ultraviolet absorption edge were determined as follows. First, a 30 × 10 mm sample having a thickness of 1.0 ± 0.02 mm, which was optically polished to such an extent that polishing scratches could not be confirmed with an optical microscope having a 30 × field of view, was prepared. Next, the transmittance | permeability in 200-800 nm was measured with the spectrophotometer (Shimadzu UV3100PC) using C standard light source, and the transmittance | permeability in 400 nm and the ultraviolet absorption edge were calculated | required. The ultraviolet absorption edge has a wavelength at which the transmittance can be regarded as substantially 0% on the short wavelength side of the light transmittance curve. Further, the Y value was calculated from the transmittance measurement data based on the XZY color system defined in JIS Z8701. Subsequently, using a UV dry processor (manufactured by Oak Manufacturing Co., Ltd.), the sample was irradiated with ultraviolet light having a dominant wavelength of 256 nm at an illuminance of 7.5 mw / cm 2 for 8 hours, and then the transmittance was measured again. The Y value and the transmittance at 400 nm were determined.
(Example 2)
Tables 3 to 7 show other examples (sample Nos. 8 to 27) of the present invention, and Table 8 shows a comparative example (sample No. 28).
[0049]
Each sample was prepared and evaluated according to Example 1.
[0050]
[Table 3]
[Table 4]
[Table 5]
[Table 6]
[Table 7]
[Table 8]
From the table, sample No. which is an example of the present invention is shown. In Nos. 8-27, the Y value after ultraviolet irradiation and the light transmittance at 400 nm were 90.9% or more and 88.7% or more, respectively, and the high transmittance was maintained after ultraviolet irradiation.
[0057]
【The invention's effect】
As described above, the glass for electric lamps of the present invention is free from coloring by ultraviolet rays or leakage of ultraviolet rays to the outside of the tube, and it is possible to produce a high-intensity compact fluorescent lamp, which is suitable as a glass for electric lamps. It is. In this specification, the bulb glass of the compact fluorescent lamp has been mainly described. However, the glass of the present invention is not limited to this, and is used for other lamps (for backlight fluorescent lamps used in liquid crystal displays). Bulbs, etc.) and other lighting members (stems, exhaust pipes, etc.).
[Brief description of the drawings]
FIG. 1 is a graph showing a change in Y value before and after ultraviolet irradiation.
Claims (4)
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| JP2002137935A (en) * | 2000-10-26 | 2002-05-14 | Nippon Electric Glass Co Ltd | Glass for fluorescent lamp, glass tube for fluorescent lamp and fluorescent lamp |
| JP4677710B2 (en) * | 2003-10-17 | 2011-04-27 | 東ソー株式会社 | Ultraviolet shielding glass, manufacturing method thereof, ultraviolet shielding glass member and apparatus using the same |
| DE102004033653B4 (en) | 2004-07-12 | 2013-09-19 | Schott Ag | Use of a glass for EEFL fluorescent lamps |
| DE102005000664B4 (en) * | 2005-01-04 | 2009-09-03 | Schott Ag | Method for adjusting the UV absorption of glasses and glass ceramics and use of glasses and glass ceramics |
| JP5456317B2 (en) * | 2006-09-28 | 2014-03-26 | 日本板硝子株式会社 | Glass composition and glass article using the same |
| JP2009224134A (en) * | 2008-03-14 | 2009-10-01 | Nec Lighting Ltd | Glass bulb for fluorescent lamp, and fluorescent lamp |
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| JP2000290038A (en) * | 1999-02-01 | 2000-10-17 | Nippon Electric Glass Co Ltd | Glass for fluorescent lamp, glass tube for fluorescent lamp and fluorescent lamp |
| JP2001031442A (en) * | 1999-07-22 | 2001-02-06 | Nippon Electric Glass Co Ltd | Glass composition for electric lamp |
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| JP2000290038A (en) * | 1999-02-01 | 2000-10-17 | Nippon Electric Glass Co Ltd | Glass for fluorescent lamp, glass tube for fluorescent lamp and fluorescent lamp |
| JP2001031442A (en) * | 1999-07-22 | 2001-02-06 | Nippon Electric Glass Co Ltd | Glass composition for electric lamp |
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