JP2001172044A - Glass used for neck of cathode ray tube - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a glass used for a neck of cathode tube, made from such components as to be enough kept in quantity as industrial resources, and giving a small elusion amount of lead into water. SOLUTION: This glass used for the neck of cathode tube has the following characteristics: an elusion amount of lead of <=5.0 μg/cm2, when the glass is dipped in distilled ion-exchanged water at 90 deg.C for 20 hr; an X-ray absorption coefficient of >=80 cm-1, when measured at a wave length of 0.06 nm; a temperature of <=995 deg.C at which the glass attains a viscosity of 104 poise; and a softening point of <=660 deg.C.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a glass used for a neck of a cathode ray tube used for television reception, computer terminal display and the like.

[0002]

2. Description of the Related Art A cathode ray tube is constituted by a panel for displaying an image, a neck for accommodating an electron gun, and a funnel for connecting the two. Each of these three parts is formed into a desired shape in a separate process and then joined to form a cathode ray tube.

In a cathode ray tube, a high voltage is applied to an anode to emit electrons to irradiate the phosphor in order to emit light from the phosphor applied to the inner surface of the panel. Since X-rays are generated at this time, the glass used for the cathode ray tube is required to have an X-ray absorption function. However, these three parts of the glass are required to have different properties besides the X-ray absorption function, and are made of glasses having different compositions. That is, in order to block the generated X-rays and prevent the panel from coloring with the X-rays, SrO or BaO is used as a component for blocking the X-rays, and PbO is not used.
The neck or funnel is X higher than the panel
Since a X-ray absorption function is required, Pb having a larger X-ray absorption coefficient than SrO or BaO is used as a component for shielding X-rays.
O is used in large quantities.

[0004]

Some of the cathode ray tubes whose life has expired are recovered and reused, while others are stored as industrial waste in a controlled place. Among them, the cathode ray tube whose life has been stored and managed outdoors is exposed to long-term rainwater, and glass components may be melted out. In particular, there is a possibility that lead may be dissolved from the conventional funnel or neck glass containing lead.

In recent years, as a measure against the lead elution problem, there is a demand for a neck glass having a small amount of lead elution into water. In order to reduce the amount of lead eluted from glass for a cathode ray tube funnel into water, Japanese Patent Application Laid-Open No. 7-206471 proposes a glass in which PbO, one of the main components, has been replaced with TiO ₂ and Bi ₂ O ₃ . . However, when the content of Bi ₂ O ₃ or TiO _{2 in} the neck glass is increased, the production of the cathode ray tube is extremely large, so that problems such as depletion of bismuth resources or titanium resources and soaring of production cost occur. There is a risk. Further, when the content of TiO ₂ is increased, the X-ray absorption function may be reduced.

Japanese Patent Publication No. 54-34769 discloses, in terms of mass percentage, SiO ₂ : 43 to 55%, Al
₂ O ₃ : 0.5 to 4.5%, Na ₂ O: 0.5 to 3%, K _{2
O: 10~14%, Li 2 O} : 0~1%, Na 2 O + K 2
O + Li ₂ O: 11 to 15%, PbO: 28 to 35%,
ZnO: 0.5-6%, CaO: 0-0.4%, Mg
O: 0~2%, BaO: 0~5 %, ZrO 2: 0~4
%, SrO: 0~6%, WO 3: 0~2%, Al 2 O 3 +
CaO + MgO + ZnO + ZrO ₂ : 3 to 8%, Al ₂ O
_{3 + ZnO + ZrO 2: 2.5} % or more, PbO + ZnO +
A glass having BaO + ZrO ₂ + SrO + WO ₃ : 3.3% or more has been proposed as a high lead glass having excellent X-ray absorption ability and chemical durability. However, these glasses have a high softening point and may be difficult to fuse with a funnel, or may have a high glass forming temperature and may be difficult to form.

An object of the present invention is to provide a glass for a neck which is used for a conventional glass for a neck of a cathode ray tube and is composed of a component which can be secured quantitatively as an industrial resource and has a small amount of lead eluted into water.

[0008]

SUMMARY OF THE INVENTION According to the present invention, a wavelength 0.06
X-ray absorption coefficient in nm is 80 cm ^-1 or more and viscosity is 1
0 ⁴ poise become temperature is 995 ° C. or less, a softening point of 660
A glass for a cathode ray tube neck having a lead elution amount of 5.0 μg / cm ² or less, which is not more than 0 ° C. The amount of lead eluted here is obtained by dividing the mass of lead present in the water after immersing the glass in 90 ° C. water subjected to distillation and ion exchange for 20 hours by the surface area of the glass.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the present invention, a wavelength of 0.06 n
The X-ray absorption coefficient μ at m is calculated by the following equation. μ = Σ (f _i × W _i ) × ρ ÷ 100 where f _i is the content of each component constituting the glass expressed as a mass percentage when expressed as an oxide, and W _i is those at a wavelength of 0.06 nm. The mass absorption coefficient of the oxide (unit: cm ² / g), ρ is the density of glass (unit: g / g)
cm ³ ). The μ of the glass for a neck of a cathode ray tube of the present invention (hereinafter simply referred to as the glass of the present invention) is 80 cm ⁻¹ or more, and preferably 85 cm ⁻¹ or more.

The temperature at which the viscosity of the glass of the present invention becomes 10 ⁴ poise is 995 ° C. or less. If it exceeds 995 ° C., glass molding may be difficult. Preferably it is 985 ° C or less, more preferably 980 ° C or less. 10 ⁴ viscosity
The temperature at which poise occurs is hereinafter referred to as a working point.

The devitrification temperature of the glass of the present invention is preferably 950 ° C. or less. If the temperature exceeds 950 ° C., crystals may precipitate on the glass and the transparency may be lost. It is more preferably at most 930 ° C, particularly preferably at most 910 ° C.
The expansion coefficient of the glass of the present invention is 92 × 10 ^{−7 to} 98 × 10.
It is preferably ⁻⁷ / ° C. If it is less than 92 × 10 ⁻⁷ / ° C. or more than 98 × 10 ⁻⁷ / ° C., strain may remain at the junction between the neck and the funnel and break. More preferably, it is 93 × 10 ^{−7 to} 97 × 10 ⁻⁷ / ° C. In addition, the expansion coefficient referred to in the present invention is an average linear expansion coefficient at 0 to 300 ° C.

The softening point of the glass of the present invention is 660 ° C. or less. If it exceeds 660 ° C., it may be difficult to fuse with the funnel. Preferably it is 650 ° C or lower, more preferably 645 ° C or lower. The softening point is preferably 620 ° C. or higher. If the temperature is lower than 620 ° C., the neck may be deformed when the neck and the funnel are fused.
More preferably 625 ° C or higher, particularly preferably 635 ° C
That is all.

The lead elution amount of the glass of the present invention is 5.0 μg /
cm ² or less. This is smaller than the lead elution amount of conventional glass for a cathode ray tube neck (hereinafter simply referred to as conventional glass), typically about 6.9 μg / cm ² , and is excellent in environmental protection. Preferably 4.9 μg / cm ²
Or less, more preferably 4.5 .mu.g / cm ² or less, particularly preferably 4.0 [mu] g / cm ² or less.

The glass of the present invention is substantially represented by the following oxide percentage by mass percentage: SiO ₂ 40 to 60%, Al ₂ O ₃ 0 to 5%, Na ₂ O 3 to 10%, K ₂ O 5-15%, PbO 20-35%, MgO 0-7%, CaO 0-7%, SrO 0-10%, BaO 0-15%, ZnO 0-5%, ZrO ₂ 0.5-3%, Sb ₂ O ₃ is preferably 0 to 1%. This preferred composition is described below.

When the content of SiO ₂ is less than 40%, the chemical durability is deteriorated, and the amount of lead eluted may increase. It is preferably at least 45%. On the other hand, if it exceeds 60%, the working temperature range of the glass becomes small, and crystals may precipitate on the glass and the transparency may be lost. Preferably it is 55% or less. The working temperature range referred to here is a value obtained by subtracting the devitrification temperature from the working point. If the working temperature range is smaller, crystals are more likely to precipitate on the glass and lose transparency.

Al ₂ O ₃ is not an essential component, but may be contained up to 5% in order to improve alkali resistance.
If it exceeds 5%, the softening point and / or working point may be too high. It is more preferably at most 3%, particularly preferably at most 1.5%. When Al ₂ O ₃ is contained, the content is more preferably 0.5% or more.

If the content of Na ₂ O is less than 3%, the softening point and / or working point may be too high. It is preferably at least 3.1%, more preferably at least 4%. If it exceeds 10%, the electric resistance may decrease. It is preferably at most 8%, more preferably at most 6%.

K ₂ O is a component for increasing the electric resistance and adjusting the expansion coefficient due to the mixed alkali effect with Na ₂ O, and is essential. If it is less than 5%, the electric resistance may be reduced and / or the expansion coefficient may be too small.
It is preferably at least 6%, more preferably at least 6.5%. If it exceeds 15%, the expansion coefficient becomes too large, and it may be difficult to fuse with the funnel. Preferably 10
%, More preferably 9% or less.

PbO is an essential component for improving the X-ray absorption function. If it is less than 20%, the content of BaO, SrO, etc. must be increased in order to obtain a predetermined X-ray absorption function, and the devitrification temperature may increase.
It is preferably at least 23%. If it exceeds 35%, the amount of lead eluted may increase. Preferably it is 32% or less.

MgO is not essential, but may be contained up to 7% in order to adjust the softening point. If it exceeds 7%, the softening point and / or working point may be too high. It is more preferably at most 5%.

[0021] CaO is not essential, but may be contained up to 7% in order to adjust the softening point. If it exceeds 7%, the softening point and / or working point may be too high. It is more preferably at most 5%, particularly preferably less than 1%.

SrO is not essential, but may be contained up to 10% in order to reduce the amount of lead eluted. If it exceeds 10%, the devitrification temperature may be too high, and crystals may precipitate on the glass and the transparency may be lost. Preferably it is 5% or less. When SrO is contained, its content is preferably 1% or more. It is more preferably at least 1.5%, particularly preferably at least 2%.

BaO is not essential, but may be contained up to 15% in order to increase alkali resistance. If it exceeds 15%, the devitrification temperature may be too high, and crystals may precipitate on the glass and the transparency may be lost. Preferably it is 12% or less. When BaO is contained, its content is preferably 1% or more. It is more preferably at least 2%.

Incidentally, PbO, MgO, CaO, SrO,
Regarding the content of BaO, PbO / (PbO + MgO +
(CaO + SrO + BaO) ≦ 0.81 is preferably satisfied. If it exceeds 0.81, the lead elution amount may be too large, or the devitrification temperature may be too high.

Although ZnO is not essential, it may be contained up to 5% in order to adjust the softening point. If it exceeds 5%, the softening point and / or working point may be too high. More preferably, it is less than 1%, and it is particularly preferable that it is not substantially contained.

ZrO ₂ is essential. Its X-ray absorption function is lower than PbO but has a moderate function,
Substitution with PbO has the effect of suppressing the amount of lead eluted while maintaining the X-ray absorption function to some extent. Since the X-ray absorption edge wavelength of Zr is shorter than Pb, ZrO
₂ also has the effect of absorbing X-rays of shorter wavelength than PbO. If it is less than 0.5%, the effect is too small. It is preferably at least 1%, more preferably at least 1.5%. If it exceeds 3%, the X-ray absorption function may be too low, and X-rays may leak. It is more preferably at most 2.5%.

Sb ₂ O ₃ is not essential, but may be contained up to 1% in order to reduce bubbles in the molten glass. 1%
The effect of reducing the foam does not increase even if the content exceeds. When Sb ₂ O ₃ is contained, its content is preferably 0.1% or more.

The glass of the present invention is preferably substantially composed of the above components, but may further contain other components such as Fe ₂ O _{3 as long as} the object of the present invention is not impaired. The total amount of the other components is preferably 10% or less. It is more preferably at most 5%. In addition, As ₂ O ₃
Has the same effect as Sb ₂ O ₃ , but may cause environmental problems and its use is not preferred.

[0029]

EXAMPLES 500 g of glass was prepared by using a reagent raw material so as to have a composition represented by mass percentage in columns from SiO ₂ to Sb ₂ O _{3 in the} table. Next, the prepared raw material is melted at 1500 ° C. using a platinum crucible, and further melted at that temperature.
After homogenizing by stirring for 1 hour, the mixture was clarified for 1 hour. After fining, the molten glass was poured into a plate having a width of 5 cm, and then gradually cooled.

The lead elution amount of the obtained glass was measured as follows. 5cm cut from the plate-shaped base glass
A sample with a corner and thickness of about 7 mm is ground and mirror-polished to 5 cm
A sample having a corner and a thickness of about 3 mm was used. After washing and drying this,
Container made of PFA (tetrafluoroethylene-perfluoro (alkyl vinyl ether) copolymer) (capacity 500c
c, about 8 cm in diameter and about 11 cm in height) in about 100 cc of distilled ion-exchanged water, and immersed at 90 ° C. for 20 hours. Here, the distilled ion-exchanged water is water obtained by ion-exchanging the distilled water.

From the distilled ion-exchanged water (immersion liquid), concentrated nitric acid was reduced to 0.
Added to 3 cc immersion liquid. The lead in the immersion liquid was quantitatively analyzed by inductively coupled plasma emission spectroscopy (IPC), and the result was divided by the surface area of the sample to obtain the lead elution amount.

The X-ray absorption coefficient (μ value) at a wavelength of 0.06 nm was determined by calculation from the glass composition, the glass density, and the mass absorption coefficient of each component. The glass density was determined from the following specific gravity. Specific gravity, softening point, expansion coefficient (α)
Are JIS Z8807 and JIS R310, respectively.
4. Measured according to JIS R3102. Also,
Measure the viscosity of the glass using a torque meter,
The temperature at which the 0 ⁴ poise was working point.

The devitrification temperature was measured as follows. Each sample was pulverized, glass particles of about 2 to 3 mm were selected, washed and dried, and then placed on a platinum-made porous boat. This platinum porous boat was placed in a temperature gradient furnace at 700 to 1200 ° C. and heat-treated for 48 hours. Then, the platinum porous boat was taken out and allowed to cool. Observing the glass sample in the platinum perforated boat with a polarizing microscope, finding the boundary position between the place where the crystal is deposited on the glass and the transparency is lost and the place where it is not,
The temperature in the electric furnace corresponding to the boundary position was determined, and this was defined as the devitrification temperature.

In the table, the amount of lead eluted (unit: μg / cm ² )
PbO ratio calculated from composition expressed in mass percentage = (Pb
O content) / (PbO, SrO, BaO, CaO, Mg
O total content), μ value (unit: cm ⁻¹ ), softening point (unit: ° C.), working point (unit: ° C.), expansion coefficient α (unit: 10 ⁻⁷ / ° C.), devitrification temperature (Unit: ° C.). Examples 1 to 4 in the table are examples of the present invention, and Example 5 is an example of a conventional typical neck glass (conventional glass) and is a comparative example.

[0035]

[Table 1]

[0036]

According to the present invention, the amount of lead dissolved in water in glass is smaller than that of conventional glass for a neck of a cathode ray tube, and the absorption coefficient and softening of X-rays having a wavelength of 0.06 nm are reduced. A glass for a cathode ray tube neck that satisfies the conditions required for a glass for a cathode ray tube neck at points, working points, and the like can be provided.

Continued on the front page F-term (reference) 4G062 AA03 BB04 DA05 DA06 DB01 DB02 DB03 DC01 DD01 DE01 DE02 DE03 DF04 DF05 EA01 EB03 EC03 EC04 ED01 ED02 ED03 EE01 EE02 EE03 EF01 EF02 EF03 EG01 EG01 FC03 EF01 FC01 FJ01 FK01 FL01 GA01 GA10 GB01 GC01 GD01 GE01 HH01 HH03 HH05 HH07 HH09 HH11 HH13 HH15 HH17 HH20 JJ01 JJ03 JJ04 JJ05 JJ07 KK01 KK03 KK05 KK07 KK10 MM25 NN14 NN34 5C032 AA02

Claims (3)

[Claims] 1. A temperature at which the X-ray absorption coefficient at a wavelength of 0.06 nm is 80 cm ^-1 or more and the viscosity becomes 10 ⁴ poise is 99.
A glass for a cathode ray tube neck having a softening point of 5 ° C. or less and a 660 ° C. or less, and a lead elution amount of 5.0 μg / cm ² or less. Lead elution amount: The mass of lead present in water after immersing the glass in 90 ° C. water subjected to distillation and ion exchange for 20 hours, divided by the surface area of the glass. In wherein following oxides in mass percentage, _{essentially, SiO 2 40~60%, Al 2} O 3 0~5%, Na 2 O 3~10%, K 2 O 5~15% PbO 20-35%, MgO 0-7%, CaO 0-7%, SrO 0-10%, BaO 0-15%, ZnO 0-5%, ZrO ₂ 0.5-3%, Sb ₂ O ₃ The glass for a cathode ray tube neck according to claim 1, comprising 0 to 1%. 3. PbO, MgO, CaO, SrO, BaO
Of the content expressed by mass percentage of PbO / (PbO
The glass for a cathode ray tube neck according to claim 1 or 2, wherein (+ MgO + CaO + SrO + BaO) ≦ 0.81 is satisfied.