JPS62288134A - Panel glass for cathode-ray tube - Google Patents

Abstract

PURPOSE:To obtain a cathode-ray tube having high X-ray absorptivity and hardly coloring by X-rays, electron rays and ultraviolet rays, particularly high resistance to browning phenomenon by electron rays, by blending Na2O with K2O at a specific ratio and further blending Li2O therewith. CONSTITUTION:The titled cathode-ray tube panel glass has the following composition expressed in terms of wt%, that is 59-63% SiO2, 0.5-2.5% Al2O3, 0-2.5% Li2O, 3-6% Na2O, 7-12% K2O, 6-12% SrO, 6-12% BaO, 0-1% ZnO, 0-5% MgO, 0-5% CaO, 0-3% ZrO2, 0.1-1% TiO2, 0.1-1% CeO2, 0-1% Sb2O3, 0-1% As2O3 and 0.15-0.40 ratio {(wt% Na2O)/[(wt% Na2O)+(wt% K2O)]} without containing PbO. The X-ray absorption coefficient is at least 28cm<-1> at 0.6Angstrom wavelength.

Description

Detailed Description of the Invention 3. Detailed Description of the Invention Field of Industrial Application The present invention relates to cathode ray tube panel glass used in color television tubes, projection tubes, and the like.

Conventional technology and problems The cathode ray tube panel glass used in color television tubes, projection tubes, etc. must absorb enough X-rays because if the X-rays generated inside the tube leak outside the tube, it is dangerous to the human body. Glass containing components such as SrO, BaO, and ZnO with high absorption capacity is used.

On the other hand, when glass is exposed to X-rays for a long time, -ffi undergoes a coloring phenomenon called browning, resulting in a brown color and a decrease in transmittance. Browning caused by X-rays gradually recovers when irradiation is stopped, and almost completely recovers when heat is applied, but browning caused by electron beams and ultraviolet rays also occurs at the same time, and the mechanism of browning caused by these is different from that caused by X-rays. It is difficult to cause discoloration, and in particular, coloring by electron beam hardly causes discoloration.

OBJECTS OF THE INVENTION An object of the present invention is to provide a cathode ray tube panel glass that has a high X-ray absorption capacity, is less colored by X-rays, electron beams, and ultraviolet rays, and has particularly high resistance to the browning phenomenon caused by electron beams. That's true.

Structure of the Invention The inventors of the present invention discovered that Na2
The mixing ratio of the two components O and K2O affects the coloring by electron beam, and Na2O weight %/(Na20 weight % + K2O
weight%) is 0.15~0840, preferably 0°20~
It has been found that when the ratio is in the range of 0.35, coloring by electron beams is reduced. It has also been found that coloring caused by electron beams can be further suppressed when Li2O is further contained.

The cathode ray tube panel glass according to the present invention has resistance to browning due to electron beams, as well as X-ray absorption ability, resistance to browning due to X-rays and ultraviolet rays, meltability, moldability, coefficient of thermal expansion, The composition was selected taking into consideration the physical characteristics, devitrification, etc., and has the following composition expressed in weighted %.

SiO2 59 to 63% ^12030.5 to 2.5% Li2O0 to 2.5% Na2O3 to 6% K2O7 to 12% Sr0 6 to 12% BaO6 to 12% ZnO 0 to 1% JOO to 5% CaO 0 to 5 %ZrO20
~3% TiO20,1~l% CeO20,1~l% Sb2O. o~! %As2
O30~1% Also preferably, it has the following composition.

SiO2 60 ~ 62% person 1□o, 0.6 ~ 2.2% Li2O
0.4-2.0% Na2O3,5-5.5% K2O 7.5-11.5%5r07-ll
% BaO3-12% ZnO 0-0.6% MgOO-4% CaO 0-4% ZrO20.5-2% TiO□ 0.2-0.8% CeO20.2-0.8% Sb2O3 o-0. 8%^52
03, 0 ~ 0. A% The reason why the composition range of the cathode ray tube panel glass of the present invention is limited as described above is as follows.

SiO2 is a glass network former,
Its content is 59-63%, preferably 60-62%. When it is less than 59%, the glass tends to devitrify and become unstable, and when it is more than 63%, the viscosity of the glass becomes too high, making melt molding difficult.

The content of Al2O is 0.5-2.5%, preferably 0.5%.
It is 6-2.2%. When it is less than 0.5%, water resistance and weather resistance deteriorate, and when it is more than 2.5%, the viscosity of the glass becomes high and it becomes difficult to melt.

Li2O is a component that suppresses browning caused by electron beams, improves the meltability of glass, and increases the coefficient of thermal expansion, and its content is 0 to 2.5%, preferably 0.4%.
~2.0%. It is preferable to contain Li2O as much as possible from the viewpoint of reducing coloration caused by electron beams, but if it exceeds 2.5%, the glass tends to devitrify, and the Li2O raw material itself is expensive, so it is also desirable from the viewpoint of cost. It is not preferable to contain Z Jlk.

Na2O and K2O are also components that improve the meltability of glass together with Li2O, and the content of Na2O is 3 to 6%, preferably 3.5 to 5.5%, and the content of K2O is 7 to 1%.
2%, preferably 7.5-11.5%. Na2O
If the amount of K2O is less than 3% and 7%, the viscosity of the glass becomes too high and melt molding becomes difficult. In addition, in the present invention, in order to reduce coloring due to electron beams, NazO
Weight%/(Na20wt% + K2Owt1%) is 0.15
It is important that it is in the range of ~0.40, but Na2O
If it is more than 6%, it becomes difficult to satisfy this range,
Further, if the K2O content is more than 12%, the coefficient of thermal expansion of the glass becomes too high.

SrO is an important component as a glass network modifier for obtaining a stable glass and has a high X-ray absorption ability, and its content is 6 to 12%, preferably 7 to .
It is 8%. If it is less than 6%, the above effects cannot be obtained, and if it is more than 12%, the glass tends to devitrify.

BaO is also included as a network modifier of the glass and to increase the X-ray absorption ability, and its content is 6.
~12%, preferably 8-12%.

If it is less than 6%, the above effects cannot be obtained, and if it is more than 12%, the glass tends to devitrify.

ZnO has the effect of increasing the X-ray absorption ability of glass, suppressing alkali elution, and increasing the weather resistance of glass.
%, preferably up to 0.6%.

MgO and CaO are each contained in an amount of 5%, preferably up to 4%, mainly to adjust the viscosity curve of the glass.
When the amount is more than 5%, the viscosity curve becomes steep.

Z'02 has the effect of increasing the X-ray absorption ability of the glass as well as the weather resistance of the glass, so it is contained in an amount of 0 to 3%, preferably 0.5 to 2%, but if it is more than 3%, the glass may be damaged. It becomes easier to see through.

TiO2 has the effect of preventing coloration due to ultraviolet rays, and its content is 0.1 to 1%, preferably 0.2 to 0.8%, but if it is more than 1%, the light transmittance of the glass will decrease. So I don't like it.

CeO2 has an excellent effect of suppressing coloration caused by X-rays, and its content is 0.1 to 1%, preferably 0.2 to 0.8%. If it is less than 0.1%, the above effect cannot be obtained, and 1
If it exceeds %, the light transmittance of the glass decreases, which is not preferable.

Sb2O3 and As2O3 are effective as glass clarifying agents and are contained up to 1% each, preferably 0.8%, but if they are more than 1%, they are undesirable because they tend to be colored by electron beams and ultraviolet rays.

In addition to the above components, in the present invention, B2O3, F2, P2O5
It is also possible to add other components.

B2O3 is beneficial for improving the meltability of the glass, but if it exceeds 3% it impairs the homogeneity of the glass.

F can be added to lower the viscosity of the glass and adjust the coefficient of thermal expansion, but if it exceeds 1.5%, the solubility of the glass deteriorates and devitrification tends to occur.

P2O5 can be added to lower the devitrification temperature of the glass, but if it exceeds 3%, a splitting phenomenon of the liquid phase occurs, and conversely, devitrification tends to occur.

Furthermore, when used in color television tube panels,
Coloring components such as Nap, COO, Feze3°Cr2O3, MnO2, Nd2O3 may be added to adjust the transmittance.

In addition, PhO is a component with the highest X-ray absorption ability among ordinary glass components, but since glass containing PbO is easily colored by electron beam irradiation, in the present invention, Pl+0
It is not desirable to introduce

Example Examples of the present invention will be described below along with reference examples.

The following table shows the glass compositions of Examples and Reference Examples, 14 a 2
The ratio of 0 weight 1% 7' (20 weight % Na and 10 weight % K2O), the X-ray absorption coefficient, and the electron beam coloring are shown. still,
The value of electron beam coloring indicates the difference in transmittance before and after electron beam irradiation at a wavelength of 400n+s.

The following margin samples Na 1 to 6 are examples of the glass of the present invention,
Samples N[L 7-9 are reference examples given for comparison.

The samples of N(L 1 to 9 shown in the table were prepared as follows.

Raw material batches prepared to have the respective glass compositions of Samples N[L1 to L9 were placed in a platinum crucible and melted at about 1450° C. for 4 hours. Stir with a platinum stirring rod halfway to obtain a homogeneous glass.
After defoaming by stirring for a minute, the mixture was poured into a mold and formed into a plate. After slow cooling, remove from the mold and polish to 20X 30
A sample piece with dimensions of X 5 +u+ was prepared.

Next, browning experiments using electron beams on glasses of samples Nos. 1 to 9 will be described.

After evaporating aluminum to a thickness of 3000λ onto a sample glass whose transmittance had been measured in advance and fixing it with a wire to the shadow mask of a color television tube, an applied voltage of 30 kV from an electron gun and a current density of the electron beam of 3 μ^/Cm were applied.
The sample glass was irradiated with an electron beam for 50 hours under the following conditions. Thereafter, the sample glass was removed from the wire, the vapor-deposited aluminum was removed, and the transmittance was measured, and the amount of electron beam coloring was expressed as the difference in transmittance at a wavelength of 400 nm before and after irradiation.

The results showed that glass containing PbO (
Sample No. 9> was the most markedly colored, with Na2Owt%/(Na20wt%) among the pbo-free glasses.
The glasses of Examples (Samples N [L 1 to 6) with a content of 0.15 to 0.40 (10% by weight of K2O) showed less coloration than the glasses of Reference Examples (Samples Nos. 7 and 8). It was difficult to wake up. Furthermore, among the glasses of Examples, the glasses containing Li2O (Samples Nos. 1 to 4) were more difficult to cause coloring than the glasses not containing Li2O (Samples Na, 5 and 6).

The drawing is based on the glass of sample No. 5 in the table above, with the total amount of Na2O and K2O constant at 15.4%.
The difference in transmittance before and after electron beam irradiation was measured for eight types of glasses made under the same melting, forming, and processing conditions as the glasses in the table above, with different ratios of 2O weight %/(Na 20 weight % + K2O weight %). This is shown in the curve diagram. Na2 on the horizontal axis
The value is taken as O weight %/(Na 20 weight % + K2O weight %), and the transmittance difference before and after electron beam irradiation at a wavelength of 400 nm is plotted on the vertical axis. Incidentally, the irradiation time was 50 hours [m]. From the drawing, Na2O weight 1%/(Na20 weight% - K2
O weight %) = 0.15 to 0.40, preferably 0.20
Coloring by electron beams is most suppressed in the range of 0.35 to 0.35. I can understand the two.

Effects of the Invention As described above, the glass of the present invention has high X-ray absorption ability, is less colored by X-rays, electron beams, and ultraviolet rays, and has high resistance to the browning phenomenon caused by electron beams. It is suitable as cathode ray tube panel glass used in television tubes, projection tubes, etc.

[Brief explanation of the drawing]

The drawing is a curve diagram showing the transmittance difference before and after electron beam irradiation at a wavelength of 400 nm for eight types of glasses with different ratios of Na2O weight %/(Na 20 weight % + K2O weight 1%). Patent applicant Nippon Electric Glass Co., Ltd. Representative Kishi 1) Saku Kiyoshi

Claims (2)

[Claims] (1) SiO_2 59-63% Al_2O_3 0.5-2.5% Li_2O 0-2.5% Na_2O 3-6% K_2O 7-12% SrO 6-12% BaO 6-12% ZnO 0 ~1% MgO 0-5% CaO 0-5% ZrO_2 0-3% TiO_2 0.1-1% CeO_2 0.1-1% Sb_2O_3 0-1% As_2O_3 0-1% It has a composition of Na_2O weight %/(Na_2O weight%
+K_2O weight%) = 0.15 to 0.40, and Pb
Cathode ray tube panel glass which is O-free and has an X-ray absorption coefficient of at least 28 cm^-^1 at a wavelength of 0.6 Å and is particularly resistant to browning by electron beams. (2) SiO_2 60-62% Al_2O_3 0.6-2.2% Li_2O 0.4-2.0% Na_2O 3.5-5.5% K_2O 7.5-11.5% SrO 7 ~11% BaO 8-12% ZnO 0-0.6% MgO 0-4% CaO 0-4% ZrO_2 0.5-2% TiO_2 0.2-0.8% CeO_2 0.2-0.8% It has a composition of Sb_2O_3 0-0.8% As_2O_3 0-0.8%, Na_2O wt%/(Na_2O wt%
+K_2O weight%) = 0.20 to 0.35, and Pb
A cathode ray tube panel according to claim 1, which does not contain O, has an X-ray absorption coefficient of at least 28 cm^-^1 at a wavelength of 0.6 Å, and is particularly resistant to browning by electron beams. glass.