KR101037166B1 - Method for cleaning lamp-glass tube for use in fluorescent-lamp - Google Patents

Abstract

The present invention relates to a method of cleaning lamp glass tubes for use in fluorescent lamps, in particular fluorescent lamps for back light. The cleaning method comprises washing the glass tube with an aqueous cleaning medium having a neutral to strong alkaline pH value, preferably in the range of about 7 to about 12, wherein the cleaning temperature is in the range of about 0 ° C to about 90 ° C. .

Fluorescent lamp, lamp glass tube, pH value, aqueous washing medium, washing temperature.

Description

Method for cleaning lamp glass tubes for use in fluorescent lamps {METHOD FOR CLEANING LAMP-GLASS TUBE FOR USE IN FLUORESCENT-LAMP}

The present invention relates to a method of cleaning lamp glass tubes suitable for use in fluorescent lamps, in particular fluorescent lamps for back light.

In a known manner, alkali-containing silicate glass, in particular borosilicate glass, is used for gas discharge lamps such as cold-cathode fluorescent lamps (CCFL) or external electrode fluorescent lamp (EEFL) -gas discharge lamps. The main components of this glass are SiO ₂ , B ₂ O ₃ and alkali oxides and alkaline earth metal oxides. For example, with a relatively high content of B ₂ O ₃ in the glass matrix of 10 to 20% by weight, this glass has a relatively low chemical resistance and low hydrolysis resistance to acids and bases.

It is also known to wash the glass tube in a washing process before the actual manufacturing process of the lamp. This cleaning process is used on the one hand to remove contaminants that cling to the outer or inner surface, for example, during transport, and on the other hand to remove the glass fragments that are present on occasion. It may also be desirable to completely or partially remove the anti-scratch layer provided, as may be the case, to prevent scratches that may occur during transport or storage.
In addition, a number of cleaning methods are known in the prior art:
US 2006/0154838 A1 discloses a cleaning composition comprising a chelating agent, an alkali compound and water having a pH value of 8 to 13, wherein a method of cleaning a semiconductor substrate on which metal wiring is disposed. The chelating agent removes metal impurities that adhere to the substrate after polishing, etching and CMP processing. The substrate has a metal or metal containing surface and is preferably a silicon wafer.
US 2004/0224866 A1 discloses a cleaning solution for semiconductor substrates comprising oxidizing agents, acids and fluoride compounds having a pH value in the range of 3 to 10 by the addition of a base compound and by a water concentration of at least 80% by weight. Also disclosed is a method of washing with the solution, in which the substance adhering to the surface of the substrate is removed.
US 6 039 815 A discloses a cleaning method using an alkaline or acid solution mixed with ozone-water as the cleaning solution.
EP 1 808 480 A1 discloses cleaning compositions, in particular cleaning compositions of photoresist residues of semiconductor substrates after plasma etching and ashing processes. The composition comprises water, one or more fluorides and pH buffer systems, one or more organic acids selected from aminoalkylsulfonic acids or aminoalkylcarboxylic acids, and one or more bases selected from amines or quaternary alkylammonium hydroxides. The composition has no organic solvent and has a pH value of 5-12.
US 2005/0245422 A1 discloses alkaline cleaners for electronic, metal or ceramic parts comprising alkali components, polyhydric alcohols and other monohydric or dihydric alcohols, preferably given in amounts of 60-95% by weight. The alcohol does not contain nitrogen atoms and has a defined molecular weight.
US 5 750 482 A relates to a glass cleaning composition comprising ethylene glycol monohexyl ether as organic solvent with a mixture of surface active agent and water, which composition removes streaks on the glass surface without streaks. The pH value is set to 3.5 to 6.5 or 7.5 to 11.5.
US 2006/0293199 A1 relates to a washing method wherein the cleaning composition comprises, for example, acids and salts, the composition comprising at least 50% by weight of water and having a pH value in the range of 1 to 10.

Such commonly practiced cleaning processes have a series of disadvantages: Due to the low chemical resistance of the glass, the reaction of the cleaning solution with the glass surface, such as elution, can occur during the cleaning process. This can mean, for example, the dissolution of the glass. That is, the glass is completely dissolved and the components of the glass are dissolved. Under normal conditions, ie at room temperature and neutral pH values, only partial dissolution of the glass appears, but this changes the shape and properties of the glass. In addition, ion exchange may occur at the glass surface, for example, alkali ions may be dissolved from the glass and exchanged for protons (H ⁺ ), and B ₂ O ₃ may also be decomposed from the glass matrix.

The reaction of the cleaning solution with the glass has a negative effect on the subsequent treatment of the glass. In subsequent heat treatment, for example, in a so-called "baking process" in which a subsequent tempering step, such as a fluorescent layer, is baked on the inner side of the tube (eg at a maximum temperature in the range of about 500 ° C to about 750 ° C, typically 600 ° C to 700 ° C) ), Contraction of the tube ("shrinkage" or "compaction") occurs. "Compaction" means, in the scope of the present invention, irreversible local compression corresponding to shrinkage of the material in the molecular plane. The separation of components such as alkali ions or B ₂ O ₃ from the glass matrix causes the network to become a “coarse mesh” so that the network becomes tight upon heating of the tube.

This can therefore lead to deformation, in particular shortening of the tube length. The shortening of these tubes can range from about 0.5% to 10%. This means that in the worst case, the tubes cannot be used for their intended use because of their shortening and must be separated as defective.

It is an object of the present invention to provide a cleaning method which reduces or completely inhibits the "shrinkage" of the uniaxial form of the tube in the subsequent heat treatment caused by the reaction of the cleaning medium with the glass surface. The aim is to reduce the variation in “shrinkage”, ie to obtain as uniform uniform variation in length as possible on average in large quantities of tubes, nevertheless the cleaning method must meet its original purpose of satisfactorily cleaning the glass surface.

The object is a cleaning method of a lamp glass tube for use in a fluorescent lamp, in particular a fluorescent lamp for backlights, according to the invention,

Washing the glass tube with an aqueous cleaning medium having a neutral to strong alkaline pH value, preferably in the range of about 7 to about 12,

The cleaning temperature is achieved by a method of cleaning a lamp glass tube, characterized in that it ranges from about 0 ° C to about 90 ° C, preferably in the range of 20 ° C to <80 ° C.
The invention also relates to a process for the treatment of lamp glass tubes for use in fluorescent lamps, in particular fluorescent lamps for backlights.
(1) washing the glass tube with an aqueous cleaning medium having a neutral to about alkaline pH value, preferably a pH value in the range from about 7 to about 12, wherein the wash temperature is from about 0 ° C to about 90 ° C, Washing method, preferably in the range of about 20 ° C to <80 ° C; and
(2) It includes a tempering method.

Surprisingly, it has been shown that when the cleaning process is carried out under defined conditions, the undesirable effects of "shrinkage" can be reduced to a minimum or completely prevented. Critical conditions are the pH value and wash temperature of the wash medium. The duration of the wash, ie how long the glass tube is exposed to the wash medium, is less important. Considering these critical conditions, a significant reduction in rejects and an increase in glass tube yield are achieved, which affects the economics of the process, especially in processes carried out on large industrial scale.

The washing medium is an aqueous medium and the main component of the washing medium consists of water. Water is present in the washing medium in a range of greater than 50%, preferably 60%, particularly preferably 70%, in particular 80%. Especially preferably the washing liquid is an aqueous solution.

The boundary condition that must be observed in the cleaning process is that a neutral to strong alkaline pH value must be set in the cleaning medium. The pH value is preferably in the range of 7 to 12, particularly preferably in the range of 7 to 9 or in the range of 9 to 12. It is particularly preferred that the pH value range be set, because the surface of the glass is thereby not eroded by the cleaning solution or only very minimally. The pH range of 7 to 9 has the advantage that the cleaning solution has low erosion (work protection, environmental protection), but the cleaning effect is low. The pH range of 9 to 12 has the particular advantage that the cleaning effect is very good, especially when the tube is heavily soiled. Contamination is mainly organic contamination such as, for example, oils or the like (eg by fingerprints), which can be better removed in alkaline solutions (unlike acid solutions).

It is particularly preferred according to the invention that the pH value remains constant during the whole washing process. This can be done, for example, by continuous control of the pH value and optionally by the addition of additives such as weak acids and / or bases. It is also possible to recover or maintain the original pH value by, for example, changing the wash medium continuously or occasionally during the wash.

Another possibility is to add a pH-buffer system that maintains the set pH value to the wash medium, causing the pH value to change only marginally. Exemplary buffer systems that can be used include KH ₂ PO ₄ / NaOH (pH range 5.8-8.0) or KH ₂ PO ₄ / Na ₂ HPO ₄ (pH 5.4 to 7.8) Na ₂ HPO ₄ / NaOH (pH 10.9 to 12.0). Phosphate buffers, such as Tris / HCl (pH range 7.0 to 9.0), borax buffers such as Borax / HCl (pH range 9.2 to 10.8), carbonate-carbonate buffers (pH range 6.2 to 11.0), ammonia buffer NH ₃ + H ₂ O + NH ₄ Cl (pH 8.2-10.2) and many other buffer systems known to those skilled in the art. By setting the component ratio of the buffer solution, a predetermined pH value can be arbitrarily set in a possible range. This is shown for some examples in the table below:

Available pH Range A x ml B Set pH value
(Buffer mixture consisting of 50 ml A + x ml B) 5.8-8.0 0.1 m KH ₂ PO ₄ 3.6 ml 0.1 m NaOH 5.8 5.8-8.0 0.1 m KH ₂ PO ₄ 46.1 ml 0.1 m NaOH 8.0 7.0-9.0 0.1 m Tris 46.6 ml 0.1 m HCl 7.0 8.0-9.1 0.025 m Borax 20.5 ml 0.1 m HCl 8.0 7.0-9.0 0.1 m Tris 5.7 ml 0.1 m HCl 9.0 9.2-10.8 0.025 m Borax 0.9 ml 0.1 m HCl 9.2 9.6-11.0 0.05 m NaHCO ₃ 5.0 ml 0.1 m NaOH 9.6 9.2-10.8 0.025 m Borax 24.25 ml 0.1 m NaOH 10.8 10.9-12.0 0.05 m Na ₂ HPO ₄ 3.3 ml 0.1 m NaOH 10.9 9.6-11.0 0.05 m NaHCO ₃ 22.7 ml 0.1 m NaOH 11.0 10.9-12.0 0.05 m Na ₂ HPO ₄ 26.9 ml 0.1 m NaOH 12.0 12.0-13.0 0.2 m KCl (25 ml) 6.0 ml 0.2 m NaOH 12.0

Tris: tris (hydroxymethyl) aminomethane

Final volume of mixture = 100 ml buffer solution.

It has also been found that surprisingly low washing temperatures are desirable. Temperatures between about 0 ° C. and about 90 ° C., in particular between about 20 ° C. and <80 ° C., are preferred. Preference is given to temperatures of about 20 ° C. to <70 ° C., in particular about 25 ° C. to <50 ° C. The expression “about” means a value that is 1 to 10% higher or lower, preferably up to 20% higher or lower with respect to a number or range. All intermediate values in a range are considered to be publicly available.

In view of this temperature range, the glass surface is not eroded or eroded only to a very small extent.

Unexpectedly, the cleaning time has been shown to have a secondary effect on the shrinkage of the glass tube during heat treatment, either at lower temperatures and for longer periods of time to obtain a good cleaning effect with less shrinkage. Or it is particularly preferred to wash at a higher temperature for a shorter time, with the latter being less preferred: “lower temperature” means a temperature in the lower range of the given range, and “higher temperature” in the range of the given temperature It means the temperature in the high range.

It has been found to be particularly desirable to add one or a plurality of compounds to assist in the cleaning of the glass to the cleaning medium. Compounds that support the cleaning of the glass are, for example, surfactants which are divided into anionic, cationic, nonionic and amphoteric surfactants.

Anionic surfactants are, for example, alkylbenzolsulfonates, alkanesulfonates, fatty alcohol sulfates, fatty alcohol ethersulfates, alkylphosphates, alkyletherphosphates. Soaps are included in the anionic surfactants and are substantially the sodium and potassium salts of higher fatty acids.

Nonionic surfactants are, for example, fatty alcohol ethoxylates, alkylphenolethoxylates, fatty amine ethoxylates, fatty acid ester ethoxylates, alkanolamides and amine oxides.

Cationic surfactants are, for example, alkylammonium compounds or imidazolinium compounds.

Amphoteric surfactants are, for example, sulfobetaine and taurine.

Particularly preferred surfactants are surfactants such as soaps having neutral to about basic pH values.

The surfactant or surfactants are given in amounts of about 0.1 to about 20 weight percent, preferably about 0.5 to about 10.0 weight percent, especially about 1 to about 5 weight percent.

It is also desirable to add a complex former to the wash medium, for example to complex the separated ions, such as alkali ions, alkaline earth metal ions, and thus bind, to prevent reaction with the glass or wash medium components. Suitable complexing agents are described in the chemical literature and may be, for example, EDTA, poly (hydroxycarboxylate), crown ethers or others.

According to another preferred embodiment of the present invention, neutral salts for increasing the ion concentration may further be added to the washing medium. These are common salts that do not react with the glass and wash media components. Examples include NaCl, Na ₂ SO ₄ , CaCl ₂ , KCl, K ₂ SO ₄ , KBr and the like.

The washing solution according to the invention has for example the following composition:

About 0.5 to about 10 weight percent of one or multiple surfactants

Preferably from about 1 to about 5 weight percent

About 0.5 to about 5 weight percent of buffer system

Optionally one or multiple

About 0.5 to about 5 weight percent of a neutral salt

Optionally one or multiple

About 0.5 to about 5 weight percent of a complex former

Remaining portion relative to 100% by weight of water.

Additives such as surfactants, buffer systems, salts, complexing agents or other additives that do not affect the cleaning process of the present invention by not causing undesirable reactions are added to the cleaning medium and are used for the cleaning medium. .

The glass of the glass tube is not particularly limited in the scope of the present invention. As the tubular glass, glass based on borosilicate glass or soda lime glass is particularly preferably used. The glass can include all known glasses.

Particularly preferred glasses for the above process have, for example, the following glass compositions:

SiO ₂ 50-70 wt%

B ₂ O ₃ 5-20 wt%

Al ₂ O ₃ 1-13 wt%

Li ₂ O 0-5 wt%

Na ₂ O 0-10 wt%

K ₂ O 0-10 wt%

Li ₂ O + Na ₂ O + K ₂ O 3-15 wt%

MgO 0-5 wt%

CaO 0-10 wt%

SrO 0-5 wt%

BaO 0-15 wt%

TiO ₂ 0-10 wt%

Preferably> 0.5-10% by weight

Especially> 0.5-5% by weight

ZrO ₂ 0-3 wt%

CeO ₂ 0-5 wt%

Fe ₂ O ₃ 0-1 wt%

WO ₃ 0-3 wt%

Bi ₂ O ₃ 0-3 wt%

MoO ₃ 0-3 wt%

ZnO 0-5 wt%

SnO ₂ 0-2 wt%

And Rh, Hf, Ta, W, Re, Os, Ir, Pt, La, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu (oxide form) 0-5 weight %.

Also preferred are, for example, so-called soda lime glasses having the following compositional ranges:

SiO ₂ 50-80 wt%

B ₂ O ₃ 0-5 wt%

Al ₂ O ₃ 0-5 wt%

Li ₂ O 0-5 wt%

Na ₂ O 0-10 wt%

K ₂ O 0-10 wt%

Li ₂ O + Na ₂ O + K ₂ O 3-20 wt%

MgO 0-5 wt%

CaO 0-10 wt%

SrO 0-5 wt%

BaO 0-15 wt%

MgO + CaO + SrO + BaO 3-20 wt%

TiO ₂ 0-10 wt%

Preferably> 0.5-10% by weight

Especially> 0.5-5% by weight

ZrO ₂ 0-3 wt%

CeO ₂ 0-5 wt%

Fe ₂ O ₃ 0-1 wt%

WO ₃ 0-3 wt%

Bi ₂ O ₃ 0-3 wt%

MoO ₃ 0-3 wt%

ZnO 0-5 wt%

SnO ₂ 0-2 wt%

And Rh, Hf, Ta, W, Re, Os, Ir, Pt, La, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu (oxide form) 0-5 weight %

And optionally a tablet agent selected from conventional concentrations, in particular chloride, sulfate, As ₂ O ₃ and / or Sb ₂ O ₃ . SnO ₂ is particularly preferably used for high temperature purification.

In the glass compositions it may be desirable to have both ceroxide and tin oxide present at the same time. Too much content of the seroxide discoloration can be suppressed by the presence of tin oxide.

The shape of the glass tube is not particularly limited according to the present invention. All cross sections available for the lamp can be used in the cleaning process according to the invention. Typical cross-sections of lamps correspond to the spatial conditions in the backlight, for example. Round, oval, rectangular and / or planar, rectangular cross sections (such as Osram Planon ^® ) are preferred, and cross-sections used for lamps for backlights, such as planar rectangular cross sections, are particularly preferred.

The glass tubes used in the cleaning process according to the invention are suitably subsequently processed to form casing glass of fluorescent lamps, preferably small fluorescent lamps. For this purpose, the glass tubes are heat treated after the washing process according to the invention. The heat treatment is a tempering step, such as a so-called "baking process," and a maximum temperature in the range of about 500 ° C. to about 750 ° C., typically 600 ° C. to 700 ° C., is used where the fluorescent layer is baked on the inner side of the tube.

Fluorescent lamps preparable with glass tubes can preferably be used for the back light of flat panel displays, in particular LCD-TFT displays. For this use, the lamp has very small dimensions and therefore the lamp glass has only extremely small thicknesses. For example, the glass tube may be tubular and the diameter is <1.0 cm, preferably <0.8 cm, particularly preferably <0.7 cm, more particularly preferably <0.5 cm. The wall thickness of the tubular casing glass is <1 mm, in particular 0.7 mm. In an alternative embodiment, the glass tube of the lighting means can have a thickness <1 cm. Preferred displays, so-called flat displays, are used in laptops, in particular flat backlight devices.

Fluorescent lamps that can be manufactured are preferably small backlight lamps. The lamps can be divided into two parts, the middle part being transparent and present in the form of casing glass, and a suitable connection by insertion of a metal or metal alloy wire. The metal and metal wire may be melted together with the casing glass in the tempering step. Metal or metal alloy wires are electrode feedthroughs and / or electrodes. The electrode feedthrough is preferably a tungsten- or molybdenum-metal or Kovar alloy. Since the coefficient of thermal expansion (CTE) of the casing glass coincides with the coefficient of thermal expansion (CTE) of the electrode feedthrough, no stress occurs in the region of the feedthrough or only a stress that is defined and intentionally used. Particularly preferred backlight lamps are external electrode fluorescent lamps (EEFL) without electrode feedthrough, because of the electric field coupling occurs in electrodeless EEFL-backlights. Cold-cathode fluorescent lamps are also known, in which the ignition of the plasma takes place via the inner electrode.

By the present invention, there is provided a cleaning method that reduces or completely inhibits the "shrinkage" of the uniaxial form of the tube in subsequent heat treatment caused by the reaction of the cleaning medium with the glass surface.

In the following, the present invention will be described by examples showing the idea according to the present invention, but the present invention is not limited to these examples.

Example :

Glass tubes were made with the following borosilicate glass compositions:

Example 1 SiO ₂ 66 Al ₂ O ₃ 2.5 B ₂ O ₃ 18 Li ₂ O 0.5 Na ₂ O 0.5 K ₂ O 7.5 MgO CaO SrO BaO ZnO 0.5 ZrO ₂ As ₂ O ₃ Sb ₂ O ₃ 0.5 Fe ₂ O ₃ TiO ₂ 4 synthesis 100

The shape of the tube was as follows:

Outer Diameter: 3.4mm

Inner diameter: 2.4 mm

Wall thickness: 0.5mm

Length of pipe: 500 mm.

The glass tube with the above composition and the dimensions was washed by the washing method according to the invention. In this case, the shrinkage (in mm) of each glass tube was analyzed for different pH values depending on wash time and wash temperature. The results are shown in Figures 1-3.

1 shows a washing method at a pH value of 4.5. The pH value is outside the pH range according to the invention and is set too acidic, indicating a clear increase in shrinkage at higher temperature ranges. Exceeding 45 ° C. already results in a very detrimental effect on the glass tube, which leads to a deformation of the glass tube, which deformation renders the glass unusable for the intended use in the lamp for backlight.

Figure 2 shows a washing method according to the invention carried out with a pH value of 7. The range with different shrinkages, shown in FIG. 1, is much wider, preferably allowing for heat treatment to temperatures below 70 ° C.

3 shows a washing method according to the invention carried out with a pH value of 9. As shown in FIG. 3, a pH range of 8 to 9 is particularly preferred. Substantial shrinkage does not occur even with a long treatment time of 120 minutes up to above 70 ° C., so that the cleaned glass does not actually deform.

4 shows an example temperature-time program for a “baking process”. Of course, other programs are possible.

According to the present invention, there is provided a method for cleaning a glass tube made of borosilicate glass or soda lime glass, which significantly reduces or completely suppresses shrinkage. For this reason, since the defective article at the time of manufacture of a glass tube reduces, the economics of the said method can be raised significantly.

1 shows the shrinkage of the glass tube in mm according to the washing time and washing temperature at a pH value of 4.5;

2 shows the shrinkage of the glass tube in mm according to the washing time and washing temperature at a pH value of 7;

3 shows the shrinkage of the glass tube in mm according to the washing time and washing temperature at a pH value of 9;

4 is an exemplary temperature-time program for a “baking process”.

Claims (27)

A method of cleaning a lamp glass tube for use in a fluorescent lamp, Glass tube with an aqueous cleaning medium with a pH value ranging from 7 to 12, with one or more pH buffer systems selected from the group consisting of phosphate buffer, tris-buffer, borax-buffer, carbonate-carbonate buffer and ammonia buffer. Washing the step; The washing temperature ranges from 0 ° C to 90 ° C. In the method of cleaning a lamp glass tube for use in a fluorescent lamp, (1) washing the glass tube with an aqueous washing medium having a pH value in the range of 7 to 12, wherein the washing temperature ranges from 0 ° C to 90 ° C; and (2) A method for cleaning a lamp glass tube, comprising a tempering method. 3. The method of claim 1, wherein said cleaning of said glass tube is performed with an aqueous cleaning medium having a pH value in the range of 7 to 12. 4. The method of claim 1 or 2, wherein the washing temperature is a temperature range of 20 ℃ to 70 ℃. 3. The method of claim 1 or 2, wherein the pH value is kept constant by addition of acids and / or bases, or addition of wash media, during the entire wash process. delete delete delete delete delete The method according to claim 1 or 2, wherein the cleaning time is 10 to 120 minutes. 3. The method of claim 1 or 2, wherein an anionic, cationic, nonionic or amphoteric surfactant is added to the cleaning medium to assist in the cleaning of the glass. delete The lamp according to claim 1 or 2, wherein at least one neutral salt selected from the group consisting of NaCl, Na ₂ SO ₄ , CaCl ₂ , KCl, K ₂ SO ₄ and KBr is added to the washing medium. How to wash a glass tube. The lamp glass tube cleaning according to claim 1, wherein at least one complex former selected from the group consisting of EDTA, poly (hydroxycarboxylate) and crown ether is added to the cleaning medium. Way. delete The method for cleaning a lamp glass tube according to claim 1 or 2, wherein an aqueous solution is used as the cleaning medium. The method of claim 1 or 2, wherein an aqueous medium is used as the cleaning medium, and the aqueous medium contains water in the range of 50% to 90%. 13. The method of claim 12, wherein the surfactant is used in an amount of 0.1 to 20 wt%. The method of claim 1 or 2, wherein the cleaning medium comprises the following composition: 0.5-10 wt% anionic, cationic, nonionic or amphoteric surfactant 0.5 to 5% by weight of at least one pH buffer system selected from the group consisting of phosphate buffer, tris-buffer, borax-buffer, carbonate-carbonate buffer and ammonia buffer Selected from the group consisting of NaCl, Na ₂ SO ₄ , CaCl ₂ , KCl, K ₂ SO ₄ and KBr 0.5-5% by weight of one or more neutral salts At least one complex former selected from the group consisting of EDTA, poly (hydroxycarboxylate) and crown ethers 0.5 to 5 wt% Remaining portion relative to 100% by weight of water. The method for cleaning a lamp glass tube according to claim 1 or 2, wherein borosilicate glass or soda lime glass is used as the glass of the glass tube. The method of claim 1 or 2, wherein borosilicate glass is used as the glass, wherein the borosilicate glass has the following composition: SiO ₂ 50-70 wt% B ₂ O ₃ 5-20 wt% Al ₂ O ₃ 1-13 wt% Li ₂ O 0-5 wt% Na ₂ O 0-10 wt% K ₂ O 0-10 wt% Li ₂ O + Na ₂ O + K ₂ O 3-15 wt% MgO 0-5 wt% CaO 0-10 wt% SrO 0-5 wt% BaO 0-15 wt% TiO ₂ 0-10 wt% ZrO ₂ 0-3 wt% CeO ₂ 0-5 wt% Fe ₂ O ₃ 0-1 wt% WO ₃ 0-3 wt% Bi ₂ O ₃ 0-3 wt% MoO ₃ 0-3 wt% ZnO 0-5 wt% SnO ₂ 0-2 wt% And Rh, Hf, Ta, W, Re, Os, Ir, Pt, La, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu (oxide form) 0-5 weight % The method for cleaning a lamp glass tube according to claim 1 or 2, wherein soda-lime glass having the following composition is used as the glass: SiO ₂ 50-80 wt% B ₂ O ₃ 0-5 wt% Al ₂ O ₃ 0-5 wt% Li ₂ O 0-5 wt% Na ₂ O 0-10 wt% K ₂ O 0-10 wt% Li ₂ O + Na ₂ O + K ₂ O 3-20 wt% MgO 0-5 wt% CaO 0-10 wt% SrO 0-5 wt% BaO 0-15 wt% MgO + CaO + SrO + BaO 3-20 wt% TiO ₂ 0-10 wt% ZrO ₂ 0-3 wt% CeO ₂ 0-5 wt% Fe ₂ O ₃ 0-1 wt% WO ₃ 0-3 wt% Bi ₂ O ₃ 0-3 wt% MoO ₃ 0-3 wt% ZnO 0-5 wt% SnO ₂ 0-2 wt% And Rh, Hf, Ta, W, Re, Os, Ir, Pt, La, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu (oxide form) 0-5 weight %. 3. A method according to claim 1 or 2, wherein the shape of the glass tube is selected from round, oval and rectangular faces. The method of claim 1 or 2, wherein the glass tube is subsequently processed after washing to form a fluorescent lamp. 3. The method of claim 2, wherein the tempering is at a temperature in the range of 500 ° C to 750 ° C. 27. The method of claim 2 or 26, wherein a fluorescent layer is baked on the inner side of the tube upon tempering.

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