JP2002211948A - Funnel glass for cathode-ray tube - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a funnel glass for a cathode-ray tube less liable to foaming even when As2O3 or Sb2O3 is not used as a refining agent. SOLUTION: The funnel glass does not substantially contain As2O3 and Sb2O3 but contains 0.01 to <0.5 mass% CeO2.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a funnel glass for a cathode ray tube, and more particularly to a funnel glass used for an envelope of a color cathode ray tube.

[0002]

2. Description of the Related Art An envelope of a cathode ray tube has a panel portion on which an image is projected, a tubular neck portion on which an electron gun is mounted, and
It consists of a funnel-shaped funnel that connects the panel and the neck. The electron beam emitted from the electron gun causes a phosphor provided on the inner surface of the panel to emit light, and an image is projected on the panel. At this time, braking X-rays are generated inside the tube, and if this leaks out of the tube through the envelope, it has a bad effect on the human body.
This type of envelope is required to have high X-ray absorption capability. For example, in the case of funnel glass, 0.6
In order to make the X-ray absorption coefficient in Å above 40 cm ⁻¹ , lead glass containing 10 to 30% by mass of PbO in glass is used.

[0003]

Incidentally, in addition to the above requirements, the funnel glass is also required to reduce bubbles remaining in the glass, which cause display defects, vacuum strength and deterioration of electric characteristics.

[0004] In order to obtain a glass having few bubbles, it is necessary to select a fining agent that generates a fining gas both in a low temperature region where the vitrification reaction starts and in a high temperature region where defoaming and homogenization of the glass melt occurs. is important. This is because the gas generated when the raw material undergoes a vitrification reaction is expelled, and the fine bubbles remaining in the glass melt during the defoaming and homogenization processes are increased to remove them by floating.

[0005] Funnel glass is usually 800-120.
A vitrification reaction occurs at 0 ° C., and defoaming and homogenization are performed at a temperature of 1400 ° C. or more. For this reason, fining agents include 80
0 to 1500 ° C. or higher temperature range in fining gas can be generated As ₂ O ₃ and Sb ₂ O ₃ has been widely used.

[0006] However, Sb ₂ O ₃ and As ₂ O ₃ are highly toxic and may pollute the environment during the glass manufacturing process or the treatment of waste glass, and their use is being restricted.

[0007] An object of the present invention is to provide a funnel glass for a cathode ray tube having less bubbles without using Sb ₂ O ₃ or As ₂ O ₃ as a fining agent.

[0008]

As a result of repeating various experiments, the present inventors have found that by adding CeO ₂ as an essential component to funnel glass, Sb ₂ O ₃ and As ₂
The present inventors have found that the number of bubbles in the product glass does not increase even if O ₃ is not used, and propose the present invention.

That is, the funnel glass for a cathode ray tube of the present invention contains substantially no Sb ₂ O ₃ and As ₂ O ₃ ,
₂ is contained in an amount of 0.01% by mass or more and less than 0.5% by mass.

[0010]

The CeO ₂ used in the present invention undergoes a valence change by a chemical reaction, and generates oxygen gas in a wide temperature range from 1000 ° C. or less to 1500 ° C. or more. Therefore, a fining effect can be obtained in a wide temperature range from the time of vitrification reaction occurring at a relatively low temperature to the time of homogenization melting at a high temperature, so that a funnel glass with few bubbles can be obtained.

Further, the funnel glass for a cathode ray tube of the present invention contains 10 to 30% by mass of PbO.
An X-ray absorption coefficient at 0.6 ° as high as 40 cm ⁻¹ or more can be obtained.

A preferred composition range of the funnel glass for a cathode ray tube of the present invention is SiO ₂ 48 in terms of mass percentage.
_{~58%, Al 2 O 3 0.5~6} %, PbO 10~3
0%, MgO 0-5%, CaO 0-6%, SrO
0~9%, BaO 0~9%, Na 2 O 3~9%, K 2
O 4-11%, ZrO ₂ 0-3%, ZnO 0-5
%, CeO ₂ 0.01% or more and less than 0.5%.

The reasons for limiting the composition of the glass in the present invention as described above are as follows.

[0014] SiO ₂ is a component that serves as a network former of glass. If it is less than 48%, the viscosity of the glass becomes low and molding becomes difficult. If it is more than 58%, the thermal expansion coefficient of the glass becomes too low. The thermal expansion coefficient of the neck glass is not matched. The preferred range is 50-57
%.

[0015] Although Al ₂ O ₃ is also a component that becomes a network former of the glass, less than 0.5% and the viscosity of the glass becomes low molding becomes difficult and often a low thermal expansion coefficient of the glass than 6% It becomes too inconsistent with the thermal expansion coefficient of the neck glass. A preferred range is 1-5%.

PbO is a component that enhances the X-ray absorption coefficient of glass, but if it is less than 10%, it will not have sufficient X-ray absorption capacity, and if it is more than 30%, the viscosity of the glass will be too low to make molding difficult. Become. The preferred range is 15-27%.

MgO is a component that makes the glass easier to melt and adjusts the coefficient of thermal expansion and viscosity. If it exceeds 5%, the glass tends to devitrify, the liquidus temperature rises, and molding becomes difficult. . Preferably it is 4% or less.

CaO, like MgO, is a component that facilitates melting of the glass and adjusts the coefficient of thermal expansion and viscosity. However, if it exceeds 6%, the glass tends to be devitrified, the liquidus temperature rises, and molding becomes difficult. It will be difficult. The preferred range is 1-5
%.

SrO and BaO are components that facilitate melting of the glass, adjust the coefficient of thermal expansion and viscosity, and further enhance the X-ray absorptivity. However, if each exceeds 9%, the glass tends to devitrify. The liquidus temperature rises and molding becomes difficult. Preferably, each is not more than 7%.

Na ₂ O is a component that adjusts the coefficient of thermal expansion and the viscosity. However, if it is less than 3%, the coefficient of thermal expansion becomes too low and does not match the coefficient of thermal expansion of the neck glass.
If it is more than 9%, the viscosity becomes too low and molding becomes difficult. The preferred range is 4-8%.

K ₂ O is also a component that adjusts the coefficient of thermal expansion and the viscosity similarly to Na ₂ O. However, if it is less than 4%, the coefficient of thermal expansion becomes too low and does not match the coefficient of thermal expansion of the neck glass. , 11%, the viscosity becomes too low and molding becomes difficult. The preferred range is 5-10%.

ZrO ₂ is a component that enhances the X-ray absorption coefficient of glass. However, if it is more than 3%, the glass tends to be devitrified, and the viscosity of the glass increases, making molding difficult.
Preferably it is 2% or less.

ZnO is a component that increases the X-ray absorption coefficient of glass and suppresses alkali elution. If it is more than 5%, however, ZnO volatilizes and aggregates due to volatilization and aggregation.
Preferably it is 4% or less.

CeO ₂ is an essential component as a fining agent. However, if it is less than 0.01%, a sufficient fining effect cannot be obtained. The effect corresponding to the soaring cost cannot be obtained. The preferred range is 0.01 to 0.45%.

[0025]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the funnel glass for a cathode ray tube of the present invention will be described in detail based on embodiments.

Table 1 shows examples of the present invention (samples No. 1 to No. 1).
4) and Comparative Examples (Sample Nos. 5 to 7).

[0027]

[Table 1]

Each sample in the table was prepared as follows.

First, 100 g of the raw material batch prepared so as to have the glass composition shown in the table was placed in a platinum triangular crucible, and was placed in a crucible for about 1 hour.
It melted at 450 ° C. for 30 minutes. Next, the molten glass was removed from the crucible, and gradually cooled to obtain a glass lump 1 shown in FIG. Subsequently, the glass lump 1 was cut into a thickness of 5 mm, and the cut surface was mirror-polished to obtain a glass sample 1a. FIG. 2 shows a glass sample 1a.
, And 2 in the figure indicates remaining bubbles in the glass.

The percentage of bubbles remaining in the glass of each sample thus obtained and the X-ray absorption coefficient were determined and are shown in the table.

The percentage of bubbles remaining in the glass was determined by taking an image of the polished surface of each sample, loading the image into a computer, and performing image processing to determine the percentage of bubbles in the cross-sectional area. The smaller the value, the faster the bubbles are cut.

The X-ray absorption coefficient is obtained by calculating the absorption coefficient for a wavelength of 0.6 Å based on the glass composition and density.

As is clear from Table 1, the sample No. Nos. 1 to 4 contain CeO ₂ , so that the ratio of bubbles remaining in the glass is as small as 18% or less.
This was equivalent to the case where s ₂ O ₃ or Sb ₂ O ₃ was used as a fining agent. In addition, since it contains PbO of 19% or more,
The X-ray absorption coefficient is as high as 62 cm ^-1 or more.

On the other hand, the sample No. 5 and No. 5 No. 6, although the ratio of bubbles remaining in the glass is small, it contains Sb ₂ O ₃ and As ₂ O ₃ , and is therefore not preferable for environmental reasons. In addition, the sample No. 7 is Ce
Since it did not contain O ₂ , the proportion of bubbles remaining in the glass was as large as 24%.

Next, the relationship between the CeO ₂ content and bubbles remaining in the glass will be described.

No. was added to the basic composition. 1 sample, CeO
₂ The relationship between the content and the bubbles remaining in the glass was investigated. Table 2 shows the compositions of the samples used in the investigation.

[0037]

[Table 2]

Each sample was prepared by the method described above, and the ratio of bubbles remaining in the glass was determined.

FIG. 3 shows the relationship between the CeO ₂ content and the bubbles remaining in the glass. In FIG. 3, the vertical axis indicates the percentage of bubbles remaining in the glass, and the horizontal axis indicates the CeO ₂ content in the glass.

As is clear from Table 2 and FIG.
To less than ₂ content of 0.5 percent, with increasing CeO ₂ content, the proportion of bubbles remaining in the glass is reduced,
When the CeO ₂ content is 0.5% or more, even if the CeO ₂ content increases, the ratio of bubbles remaining in the glass does not decrease so much. That is, even if CeO ₂ is contained at 0.5% or more, it is found that there is no effect of reducing bubbles corresponding to the content, and conversely, the cost is increased by the increased amount.

[0041]

As described above, the glass of the present invention has a thickness of 0.0
Since 1% by mass or more and less than 0.5% by mass of CeO ₂ is contained in the glass, there is little foam remaining in the glass without using Sb ₂ O ₃ and As ₂ O ₃ , and the color television It is suitable as a funnel glass for a cathode ray tube used for a John tube.

[Brief description of the drawings]

FIG. 1 is a diagram showing a glass lump used when preparing a sample for measuring the ratio of remaining bubbles in glass.

FIG. 2 is a diagram showing a cut surface of a glass sample.

FIG. 3 is a graph showing the relationship between CeO ₂ content and bubbles remaining in glass.

[Explanation of symbols]

 1 glass lump 1a glass sample 2 foam

 ──────────────────────────────────────────────────続 き Continued on the front page F-term (reference) 4G062 AA03 BB01 BB04 DA05 DA06 DB02 DB03 DC01 DD01 DE01 DE02 DE03 DF04 EA01 EB03 EC03 EC04 ED01 ED02 ED03 EE01 EE02 EE03 EF01 EF02 EF03 EG01 EG01 FC01 FC01 FC03 FF01 FG01 FH01 FJ01 FK01 FL01 FL02 GA01 GA10 GB01 GC01 GD01 GE01 HH01 HH03 HH05 HH07 HH09 HH11 HH13 HH15 HH17 HH20 JJ01 JJ03 JJ05 JJ07 JJ10 KK01 KK03 KK05 KK07 A02 BB10 BB10

Claims (3)

[Claims] 1. A funnel glass for a cathode ray tube, which is substantially free of Sb ₂ O ₃ and As ₂ O ₃ and contains CeO ₂ in an amount of 0.01% by mass or more and less than 0.5% by mass. 2. The PbO content is 10 to 30% by mass, and the absorption coefficient for X-rays at a wavelength of 0.6 ° is 4%.
2. The funnel glass for a cathode ray tube according to claim 1, wherein the diameter is 0 cm ^-1 or more. 3. The composition according to claim 1, wherein the SiO _{2 is} 48 to 58% by mass.
_{%, Al 2 O 3 0.5~6%} , PbO 10~30%,
MgO 0-5%, CaO 0-6%, SrO 0-9
_{%, BaO 0~9%, Na 2} O 3~9%, K 2 O 4
_{~11%, ZrO 2 0~3%,} 0~5% ZnO, C
3. The funnel glass for a cathode ray tube according to claim 1, wherein the content of eO _{2 is} 0.01% or more and less than 0.5%.