JP2009149488A - Method for cleaning lamp glass tube for use in fluorescent lamp - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for cleaning a lamp glass tube for use in a fluorescent lamp. <P>SOLUTION: A method is provided for cleaning a lamp glass tube for use in a fluorescent lamp, especially a backlight. The method comprises a step of cleaning the glass tube with an aqueous cleaning medium with a neutral to weakly alkaline pH value, preferably a pH value ranging from about 7 to about 12 at a cleaning temperature ranging from about 0°C to about 90°C. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a method for cleaning a fluorescent lamp, particularly a glass tube for a lamp used for background light.

For example, alkali silicate glass, especially borosilicate glass is used in a known method for a discharge lamp such as a CCFL (cold cathode fluorescent lamp) or EEFL (external electrode fluorescent lamp) discharge lamp. The main components of this type of glass are SiO ₂ , B ₂ O ₃ , and alkaline oxides and alkaline earth oxides. In these glasses, when the content of B ₂ O ₃ in the glass substrate is relatively high, for example, 10 to 20% by weight, the chemical resistance to acids and alkalis is relatively deteriorated, and the hydrolysis stability is also lowered. To do.

  Furthermore, it is known to clean the glass tube by cleaning it before entering the original lamp manufacturing process. For example, this cleaning process is to clean dirt adhered to the inside and outside during transportation, while it is possible to remove glass fragments if they are present. More preferably, if necessary, the crack-preventing layer applied partially or wholly in order to prevent cracking during transportation or storage can be removed.

  In addition, various cleaning processes are known today.

  US Patent Application No. 2006 / 0154838A1 describes a cleaning method that can clean a semiconductor substrate on a metal wire with a cleaning agent having a pH value of 8 to 13 containing a chelating agent, an alkali compound and water. The chelating agent removes metallic contaminants attached to the substrate surface after polishing, etching, and CMP. The substrate has a metal or metal-containing surface and is preferably a silicon wafer.

  US Patent Application No. 2004 / 0224866A1 describes cleaning for a semiconductor substrate in which an alkali compound is added to an oxidizing agent, an acid, and a fluorinated compound to adjust the pH value to a range of 3 to 10 and a moisture concentration of 80% by weight or more. Solvents are listed. Furthermore, a cleaning method is also described in which a substance attached to the surface of the substrate is removed using a solvent.

  US Patent Application No. 6039815A discloses a cleaning method using an alkaline solvent or an acidic solvent mixed with ozone water as a cleaning solvent.

  European Patent Application No. 1808480 A1 describes a cleaning agent for cleaning photoresist residues from a semiconductor substrate, in particular after plasma etching or ashing sverfahren. The detergent includes water, at least a fluoride, a pH buffer system composed of an organic acid and a base, the organic acid includes at least one of an aminoalkylsulfonic acid and an aminoalkylcarbon acid, and the base includes an amine and a fourth acid. It contains at least one of alkylammonium hydroxide. The composition component contains almost no organic solvent and has a pH value of 5-12.

  US Patent Application No. 2005 / 0245422A1 relates to an alkaline cleaner for electronic, metal or ceramic parts comprising an alkaline component, preferably 60-95% by weight mono- or dihydric alcohol, and polyhydric alcohol. Are listed. These alcohols do not contain nitrogen elements and have a predetermined molecular weight.

  U.S. Pat. No. 5,750,482A deals with a glass cleaner for mixing glass surfactant with water to remove dirt on the glass surface without leaving streaks, which contains ethylene glycol monohexyl ether as an organic solvent. Yes. The pH value is adjusted between 3.5 and 6.5 or 7.5 to 11.5.

  U.S. Patent Application No. 2006 / 0293199A1 deals with cleaning agents and cleaning methods having acids and salts, for example with 50% by weight or more of the composition component being water and a pH value in the range of 1-10.

A conventional cleaning process has a series of problems. During the cleaning process, due to the weak chemical resistance of the glass, the glass surface may react with the cleaning solvent, for example, elution may occur. This means, for example, melting of the glass, that is, a part or the whole of the glass is melted and the glass component flows out into the solvent. Under normal conditions such as a neutral pH value at room temperature, the glass only partially corrodes, but this also changes the shape and properties of the glass. Furthermore, ion exchange can occur on the glass surface, for example, alkali ions flow from the glass surface to the solvent and exchanged with protons (H ⁺ ), or B ₂ O ₃ elutes from the glass substrate.

The reaction between the cleaning solvent and the glass is first performed in a subsequent glass processing step, for example, a so-called “baking process” (maximum temperature is, for example, about 500 ° C. to about 750 ° C., usually 600 ° C. to The tube is shrunk (“shrinkage” or “compaction”) in a heating process in which a fluorescent layer called 700 ° C. is baked on the inside of the tube. “Compact” as used herein means irreversible, local compression and is due to the contraction of a substance at the molecular level. When the components such as alkali ions and B ₂ O ₃ are leached from the glass substrate, the “mesh width” of the network structure increases, and the network structure contracts by heating the tube.

  This can change the shape, especially the length of the tube. This tube shrinkage can occur on the order of approximately 0.5% to 10% of the dimensions. In the worst case, this shrinkage causes the tube to be discarded as garbage because it cannot be used for the intended application.

  In view of the above problems, the present invention reduces or completely prevents the tube from shrinking ("shrinking") and shrinking in shape due to the cleaning medium reacting with the glass surface by heat treatment. An object is to provide a cleaning method. In particular, the present invention aims to reduce the variation of “shrinkage”, ie to make the change in length in a number of tubes as uniform as possible. The cleaning treatment enables the original purpose of cleaning the glass surface to be satisfactorily achieved.

  In order to solve the above-described problems, an object of the present invention is to provide a method for cleaning a fluorescent lamp, particularly a glass tube for a lamp used for background light. The cleaning method involves the step of cleaning the glass tube at a neutral to slightly alkaline pH value, preferably from about 7 to about 12, preferably from about 0 ° C to about 90 ° C, preferably from about 20 ° C to 80 ° C. Washing with an aqueous washing medium at a washing temperature up to.

  It is another object of the present invention to provide a method for processing a fluorescent lamp, particularly a glass tube for a lamp used for background light. The processing method comprises: (1) the glass tube from about 0 ° C. to about 90 ° C., preferably from about 20 ° C., at a neutral to weakly alkaline pH value, preferably from about 7 to about 12. A cleaning process including a process of cleaning with an aqueous cleaning medium at a cleaning temperature of up to 80 ° C., and (2) a heat treatment (Temperfahren).

  Surprisingly, it has been discovered that the effect of undesired shrinkage (“shrinkage”) can be minimized or greatly reduced when the cleaning process is performed under certain conditions. The critical conditions are the pH value of the cleaning medium and the cleaning temperature when cleaning is performed. The cleaning period or time of how long the glass tube is immersed in the cleaning medium is only a secondary requirement. Considering the above critical conditions, the number of defective products can be greatly reduced and the performance of the glass tube can be improved. In particular, when this predetermined is executed on a large scale, an economic effect is exhibited.

  The cleaning medium is an aqueous medium, and the main component of the cleaning medium is water. Water is preferably 50% or more, preferably 60% or more, particularly preferably 70% or more, and more preferably 80% or more in the cleaning medium. In particular, the cleaning medium is preferably an aqueous solvent.

  One boundary condition that must be observed in the cleaning process is to adjust the pH value of the cleaning medium from neutral to strongly alkaline. This pH value is preferably in the range 7-12, particularly preferably in the range 7-9, or in the range 9-12. Adjusting to this pH value range has proven to be particularly advantageous because the glass surface is not corroded by the cleaning solvent or very little. When the pH range is 7 to 9, there is an advantage that the corrosiveness of the cleaning solvent decreases (protection of workers, environmental protection), but the cleaning effect also decreases. When the pH is in the range of 9 to 12, the cleaning effect is extremely high, which is advantageous particularly when the tube is very dirty. Since normal stains are mainly organic contaminants (for example, fingerprints) such as fats and oils, alkaline solvents (rather than acidic solvents) can be removed.

  According to the invention, it is particularly advantageous to keep the pH value constant throughout the entire cleaning process. This can be achieved by constantly managing the pH value and adding additives such as weak acids and / or bases as needed. It is also possible to return the pH value to the initial value or to maintain the initial value, for example, by continuously or occasionally changing the cleaning medium during cleaning.

トリス： Ｔｒｉｓ（ヒドロキシメチル）アミノメタン
混合物の最終体積＝１００ｍｌの緩衝溶剤 Furthermore, it is possible to add a washing medium to a pH buffer system adjusted so as to maintain the pH value in a wide range, thereby keeping the fluctuation of the pH value slight. Examples of the buffer system that can be used here include KH ₂ PO ₄ / NaOH (pH range 5.8 to 8.0) or KH ₂ PO ₄ / Na ₂ HPO ₄ (pH range 5.4 to 7.8) Na. Phosphate buffer such as ₂ HPO ₄ / NaOH (pH range 10.9 to 12.0), Tris buffer such as Tris / HCl (pH range 7.0 to 9.0), borax / hydrochloric acid (pH range) 9.2-10.8), borax buffer, carbonate / carbonate buffer (pH range 6.2-11.0), ammonia buffer NH ₃ + H ₂ O + NH ₄ Cl (pH range 8.2-10) .2), and other buffer systems known to those skilled in the art. By adjusting the component ratio of the buffer solvent, the desired pH value can be adjusted within a possible range. Some examples are given in the table below.

Tris: Final volume of Tris (hydroxymethyl) aminomethane mixture = 100 ml buffer solvent

  Further surprisingly, it is preferable that the temperature range is approximately 0 ° C. to approximately 90 ° C., particularly approximately 20 ° C. to 80 ° C., and the cleaning temperature is kept as low as possible depending on the application. Indicated. The temperature range is preferably about 20 ° C to about 70 ° C, particularly preferably about 25 ° C to 50 ° C. Here, “substantially” means a value or range of a value around 1 to 10%, preferably around 20%. All values within the range are explicitly disclosed.

  When observed in the above temperature range, the glass surface was not corroded or, if any, very little.

  On the other hand, it was found unexpectedly that the effect of the cleaning time on the reduction ("shrinkage") of the glass tube in the heat treatment was secondary. Therefore, in order to improve the cleaning effect and reduce the reduction at the same time, depending on the application, the time for cleaning at a low temperature can be lengthened, or the time for cleaning at a high temperature can be shortened. Is preferred over the latter. “Low temperature” means a temperature in a range below the above range, and “High temperature” means a temperature selected from a range above the above range.

  It has proven to be more advantageous to add to the cleaning medium one or more compounds that assist in the cleaning of the glass. Examples of compounds that assist in glass cleaning include surfactants, which can be classified into anionic, cationic, nonionic, and amphoteric. Examples of the anionic surfactant include alkylbenzene sulfonic acid, alkali sulfonic acid, fatty alcohol sulfonic acid, fatty alcohol ether sulfonic acid, alkyl phosphoric acid, alkyl ether phosphoric acid and the like.

  Examples of the anionic surfactant include alkylbenzene sulfonic acid, alkali sulfonic acid, fatty alcohol sulfonic acid, fatty alcohol ether sulfonic acid, alkyl phosphoric acid, and alkyl ether phosphoric acid. Soaps are classified as anionic surfactants and are basically higher fatty acid sodium and potassium salts.

  Nonionic surfactants include, for example, fatty alcohol ethoxylates, alkylphenol ethoxylates, fatty amine ethoxylates, fatty acid ester ethoxylates, alkanolamides, and amine oxides.

  Examples of the cationic surfactant include alkylammonium compounds and imidazolinium compounds.

  Examples of amphoteric surfactants include sulfobetaine and taurine.

  Particularly preferred surfactants include those having a pH value from neutral to weakly alkaline such as soap.

  The amount of the one or more surfactants is preferably about 0.1 to about 20% by weight, preferably about 0.5 to about 10.0% by weight, particularly preferably about 1 to about 5% by weight. It is.

  Furthermore, a complexing agent is added to the cleaning medium, for example, complexing open ions such as alkali ions and alkaline earths to prevent binding and reaction with glass and components of the cleaning medium. It is preferable. Suitable complexing agents are described in the chemical literature and include, for example, EDTA, poly (hydroxycarboxylate), crown ether, and the like.

According to a further preferred embodiment of the present invention, a neutral salt can be additionally added to increase the ionic concentration of the cleaning medium. This is a normal salt that does not react to glass or components of the cleaning medium. For example, NaCl, Na ₂ SO ₄ , CaCl ₂ , KCl, K ₂ SO ₄ , KBr and the like can be mentioned.

The cleaning solvent of the present invention may include the following composition components, for example.

  The addition of only such surfactants, buffers, salts, complexing agents and the like to the cleaning medium does not cause an unfavorable reaction with each other or inhibit the cleaning method of the present invention. Needless to say, this should be applied.

  The present invention is not particularly limited to glass tube glass. Particular preference is given to using a glass of lower glass (Rohrglas) based on borosilicate glass or lime-natron glass. Any known glass may be included.

Ｒｈ，Ｈｆ，Ｔａ，Ｗ，Ｒｅ，Ｏｓ，Ｉｒ，Ｐｔ，Ｌａ，Ｐｒ，Ｎｄ，Ｓｍ，Ｅｕ，Ｇｄ，Ｔｂ，Ｄｙ，Ｈｏ，Ｅｒ，Ｔｍ，Ｙｂ，Ｌｕは酸化物の状態で０〜５重量％。 Glasses in which the method is particularly advantageous have, for example, one of the following glass composition components:

Rh, Hf, Ta, W, Re, Os, Ir, Pt, La, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu are 0 to 5 in an oxide state. weight%.

Ｒｈ，Ｈｆ，Ｔａ，Ｗ，Ｒｅ，Ｏｓ，Ｉｒ，Ｐｔ，Ｌａ，Ｐｒ，Ｎｄ，Ｓｍ，Ｅｕ，Ｇｄ，Ｔｂ，Ｄｙ，Ｈｏ，Ｅｒ，Ｔｍ，Ｙｂ，Ｌｕは酸化物の状態で０〜５重量％。必要な場合は、清澄剤を通常の濃度で、特に塩化物、スルホン酸、Ａｓ_２Ｏ_３及び／又はＳｂ_２Ｏ_３から選択して用いる。特に好ましくは、高い温度−清澄の用途にＳｎＯ_２を用いる。 Preferably, furthermore, so-called lime-natron glass has the following glass composition component ratio, for example.

Rh, Hf, Ta, W, Re, Os, Ir, Pt, La, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu are 0 to 5 in an oxide state. weight%. If necessary, the fining agent is used at a normal concentration, especially selected from chloride, sulfonic acid, As ₂ O ₃ and / or Sb ₂ O ₃ . Particularly preferably, SnO ₂ is used for high temperature-clarification applications.

  The glass composition component used can preferably contain cerium oxide and zinc oxide. Thereby, it is possible to suppress the occurrence of color unevenness due to an increase in the content of cerium oxide due to the presence of zinc oxide.

  Similarly, the present invention is not particularly limited to the shape of the glass tube. The cleaning method of the present invention can be applied to any cross-sectional shape that can be used for a lamp. The normal cross-sectional shape of the lamp is adjusted to a three-dimensional object, for example, in the case of background light. Preferably, it is used in a lamp for background light such as a circular, oval, square and / or flat, square cross section (eg Planon® from Osram), particularly preferably a flat square cross section. Such a cross-sectional shape.

  The glass tube for carrying out the cleaning method of the present invention can be processed into a fluorescent lamp cover glass, preferably a miniaturized fluorescent lamp. According to the cleaning method of the present invention, it is preferable to further heat-treat the glass tube. Here, for example, as the heat treatment step, for example, the maximum temperature range in which the fluorescent layer is baked on the inside of the tube is, for example, approximately 500 ° C. to approximately 750 ° C., typically 600 ° C. to 700 ° C. "Baking process" can be given.

  Fluorescent lamps that can be produced from glass tubes can preferably be used for background light, for example background light of flat displays (so-called backlights), in particular LCD-TFT displays. Since such lamps are very small in this application, it is only preferred that the lamp glass is also very thin. For example, the glass tube may be tubular and the diameter may be preferably less than 1.0 cm, more preferably less than 0.8 cm, particularly preferably less than 0.7 cm, and even more preferably less than 0.5 cm. The wall thickness of the tubular cover glass (Huelglas) is preferably below 1 mm, particularly preferably below 0.7 mm. In an alternative embodiment, the glass tube thickness of the light source may be less than 1 cm. A preferred display or screen is a so-called flat display used in a laptop type, particularly a flat backlight device or the like.

  The manufacturable fluorescent lamp is preferably a small backlight lamp. Such lamps are preferably broadly transparent and are classified into two ends that can be fitted with a central portion made of a cover glass and a connection for inserting metal or alloy wiring. The metal or metal wiring may be welded to the cover glass in a heat treatment step. The metal or alloy wiring is an electrode lead and / or an electrode. These electrode conductors are preferably tungsten metal or molybdenum metal, or Kovar alloy. The thermal expansion coefficient (CTE) of the cover glass should be broadly matched with the thermal expansion coefficient (CTE) of the electrode conductor, so that no tension exists or the tension that is generated stays within the specified range in the conductor section. Is preferred. In a non-electrode EEFL backlight, since coupling is performed by an electric field, the backlight lamp is particularly preferably an EEFL (external electrode fluorescent lamp) having no electrode wiring. A CCFL system (cold cathode fluorescent lamp) that ignites plasma through an electrode disposed inside is also known.

  Hereinafter, in order to facilitate understanding of the present invention, description will be made using examples of the present invention, but the present invention is not limited thereto.

管の形状は以下の通りであった。
外径：３．４ｍｍ
内径：２．４ｍｍ
壁厚：０．５ｍｍ及び
管の長さ：５００ｍｍ Glass tubes were produced from the following borosilicate glass composition components.

The shape of the tube was as follows.
Outer diameter: 3.4mm
Inner diameter: 2.4 mm
Wall thickness: 0.5mm and tube length: 500mm

  The cleaning method of the present invention was carried out on a glass tube having the above composition components and the above dimensions. Here, the shrinkage (“shrinkage”) of each glass tube was measured in units of mm depending on the washing time and washing temperature for various pH values. The results are shown in FIGS. The contents shown in the drawings are as follows.

FIG. 1 shows the reduction ("shrinkage") of the glass tube according to the cleaning time and the cleaning temperature when the pH value is 4.5 in mm. FIG. 2 shows the reduction ("shrinkage") of the glass tube according to the cleaning time and the cleaning temperature when the pH value is 7, in mm units. FIG. 3 shows the reduction ("shrinkage") of the glass tube according to the cleaning time and the cleaning temperature when the pH value is 9, in mm units.
FIG. 4 shows an example of a typical relationship between temperature and time in the baking process.

  FIG. 1 shows a cleaning process when the pH value is 4.5. The pH value is adjusted to be acidic outside the range of the pH value of the present invention, and the reduction is clearly progressing at higher temperatures. Already above 45 ° C, the detrimental effect of glass tube shape change was clearly observed, making it impossible to use the glass for the intended use as a lamp for background light.

  FIG. 2 shows the cleaning method of the present invention that was carried out with a pH value of 7. The range in which various reductions shown in FIG. 1 occur is clearly dispersed, and heat treatment is possible at a temperature preferably up to 70 ° C.

  FIG. 3 shows the cleaning method of the present invention which was carried out at a pH value of 9. As shown in FIG. 3, the pH value is particularly preferably 8-9. Even when the treatment time was increased to 120 minutes, there was almost no reduction to a temperature exceeding 70 ° C., and there was almost no change in the shape of the washed glass.

  FIG. 4 shows an example of a typical relationship between temperature and time in the baking process. Obviously, other relationships can be adjusted.

  According to the present invention, firstly, a method for cleaning glass tubes, in particular borosilicate glass or lime-natron glass, is provided which can greatly reduce or completely eliminate shrinkage ("shrinkage"). This reduces the number of defective products that occur during the production of the glass tube, so that the present method can greatly improve the economy.

It is a figure which shows the reduction | decrease ("shrinkage | shrinkage") of the glass tube according to the washing | cleaning time and washing | cleaning temperature in case pH value is 4.5 in mm unit. It is a figure which shows the reduction | decrease ("shrinkage | shrinkage") of the glass tube according to the washing | cleaning time and washing | cleaning temperature in case pH value is 7 in mm unit. It is a figure which shows the reduction | decrease ("shrinkage | shrinkage") of the glass tube according to the washing | cleaning time and washing | cleaning temperature in case pH value is 9 in mm unit. It is a figure which shows the example of the typical relationship between temperature and time in a baking process.

Claims (27)

A method of cleaning a fluorescent lamp, particularly a glass tube for a lamp used in background light, the cleaning method comprising:
Neutral to weakly alkaline, preferably with a pH value in the range of about 7 to about 12, aqueous at a wash temperature in the range of about 0 ° C to about 90 ° C, especially about 20 ° C to less than about 80 ° C. A method of cleaning a glass tube with a cleaning medium. In particular, a method of processing a glass tube for a lamp used for a fluorescent lamp for background light,
(1) Neutral to weakly alkaline, preferably at a pH value in the range of about 7 to about 12, and in the range of about 0 ° C to about 90 ° C, particularly about 20 ° C to less than about 80 ° C. Cleaning the glass tube with an aqueous cleaning medium at a temperature;
(2) A process including heating.   The method according to claim 1 or 2, wherein the glass tube is washed with an aqueous washing medium with a pH value in the range of 7-9 or 9-12.   4. The cleaning temperature according to claim 1, wherein the cleaning temperature is about 20 ° C. to less than 70 ° C., particularly preferably about 25 ° C. to less than 50 ° C. 2. The method according to item 1.   The method according to any one of claims 1 to 4, wherein the pH value is kept constant in all steps of the cleaning treatment.   The method according to claim 1, wherein the pH value is constantly managed during the cleaning.   7. A method according to claim 5 or claim 6, wherein a weak acid or base is added to raise or lower the pH value that changes during the washing.   7. A method according to claim 5 or claim 6, wherein the cleaning medium is continued or replaced at any time during the cleaning to return to the original pH value or to maintain the original pH value.   The method according to claim 5 or 6, wherein a pH buffer system is added to the washing medium.   10. The method of claim 9, wherein the buffer system is selected from phosphate buffer, Tris buffer, borax buffer, carbonate-carbonate buffer, ammonia buffer, and the like.   The method according to any one of claims 1 to 10, wherein the cleaning time is about 10 minutes to about 120 minutes.   12. A method according to any one of the preceding claims, wherein one or more compounds are added to the cleaning medium to assist in cleaning the glass.   13. A method according to claim 12, wherein the one or more compounds that assist in the cleaning of the glass are selected from surfactants, in particular anionic, cationic, nonionic or amphoteric surfactants.   14. The method according to any one of claims 1 to 13, wherein one or more neutral salts are added to the cleaning medium to increase the ion concentration.   15. A method according to any one of claims 1 to 14, wherein one or more complexing agents are added to the cleaning medium.   The method according to claim 1, wherein lowering the temperature to increase the cleaning time, or increasing the temperature to shorten the cleaning time is combined with the cleaning.   The method according to any one of claims 1 to 16, wherein an aqueous solvent is used as the cleaning medium.   18. An aqueous medium having more than 50%, preferably more than 60%, particularly preferably more than 70%, in particular more than 80% water as cleaning medium. 2. The method according to item 1.   14. A surfactant according to claim 12 or claim 13, wherein an amount of surfactant of about 0.1 to about 20% by weight, preferably about 0.5 to about 10.0% by weight, particularly preferably 1 to 5% by weight, is used. The method according to claim 1. The cleaning medium has the following composition components:

20. A method according to any one of claims 1 to 19, comprising or comprising a component.   21. The method according to any one of claims 1 to 20, wherein borosilicate glass or natron-lime-glass is used as the glass of the glass tube. One of the following glass composition components:

Rh, Hf, Ta, W, Re, Os, Ir, Pt, La, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu are 0 to 5 in an oxide state. weight%,
If necessary, a fining agent selected at normal concentrations, in particular from chlorides, sulfonic acids, As ₂ O ₃ and / or Sb ₂ O ₃ ,
The method according to any one of claims 1 to 21, wherein a borosilicate glass having the following is used as glass. One of the following glass composition components:

Rh, Hf, Ta, W, Re, Os, Ir, Pt, La, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu are 0 to 5 in an oxide state. weight%,
23. A method according to any one of claims 1 to 22, wherein lime-natron glass having the following is used as glass.   24. A method according to any one of claims 1 to 23, wherein the shape of the glass tube is selected from circular, elliptical, square and / or planar, square cross-sectional shapes.   25. A method according to any one of claims 1 to 24, wherein the glass tube is processed into a fluorescent lamp, preferably a small fluorescent lamp for background light, after washing.   The method of claim 2, wherein the heating treatment is performed at a temperature in the range of at most about 500 ° C to about 750 ° C, particularly about 600 ° C to 700 ° C.   27. A method according to any one of claims 2 or 26, wherein the heating fires the phosphor layer to the inside of the tube.

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