JP2001302278A - Glass for cathode-ray tube, glass panel for cathode ray tube and method for production thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide glass for cathode ray tube, a glass panel for cathode ray tube and a cathode ray tube capable of achieving reductions of thickness and weight, and provide a method for the production thereof. SOLUTION: This matrix glass for cathode-ray tube contains 40-70 mol% SiO2, 0.1-15 mol% Al2O3, 5-20 mol% Li2O, 0.1-10 mol% Na2O, 0-15 mol% MgO, 0-15 mol% CaO, 3-15 mol% SrO, 0.1-15 mol% TiO2 and 0.1-5 mol% ZrO2 as glass components, and total amount of these components is >=85 mol%.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a glass for a cathode ray tube, a glass panel for a cathode ray tube, a cathode ray tube, a method for manufacturing the same, and the like.

[0002]

2. Description of the Related Art Conventionally, as a glass for a cathode ray tube (CRT), a glass containing a large amount of PbO, SrO, or BaO has been used. For example, Japanese Patent Publication 59-27729 discloses, BaO, SrO, cathode-ray tube faceplate containing ZrO ₂ (glass panel) is described.
However, this kind of glass has a bending strength of 50-100 MPa.
In order to secure the strength, the glass has to be thickened, and it becomes extremely heavy in order to respond to the demand for a large screen (for example, the thickness of a 36-inch cathode ray tube glass panel is 20 mm. As mentioned above, the weight is about 40 kg). The weight of the cathode ray tube largely depends on the glass panel, which causes a problem that the weight of the entire cathode ray tube using such a glass panel becomes considerably heavy.

As a countermeasure against this problem, attempts have been made to improve the strength of the glass by general physical strengthening (strengthening by heating and quenching) to make the glass panel thinner. For example, Japanese Patent No. 2940467 and Japanese Patent No. 2671
No. 766 discloses a glass panel for a cathode ray tube manufactured by physical strengthening.

[0004] Generally, the flexural strength of physically tempered glass such as air-cooled tempered glass is generally set to 200 to 300 MPa. Physically strengthened glass, which forms a compressive stress layer on the glass surface by quenching the glass from the vicinity of the softening point to the vicinity of the strain point to create a temperature difference between the inside and the surface of the glass, has a stress-strain layer of about 1/6 of the plate thickness. There are benefits to be gained. However, there is a drawback that physical strengthening is not suitable for thin glass in which a temperature difference between the glass surface and the inside is hardly created or glass having a complicated shape in which a uniform temperature distribution cannot be obtained. CR
The glass panel for T generally has a complicated shape in which a skirt (frame) -shaped portion (joining portion with a funnel) is provided outside a plane portion on which an image is projected. The outside of the image display unit is a flat surface, but the inside has a curvature due to scanning by an electron gun. There is a difference in the thickness of the glass by that amount, so that the cooling becomes uneven and the panel surface is likely to be warped or undulated. Further, the air-cooled tempered glass has a tensile stress layer having a size of about 1/2 of the compressive stress inside the glass. Compressive stress of general air-cooled tempered glass is 50-150MPa, tensile stress is 25-75M
Pa. Therefore, when the crack propagates inside, the large tensile stress is released at once, and a phenomenon called self-destruction may occur. The use of such physically tempered glass for CRT panels is therefore problematic. For the above reasons, for example, the physically reinforced glass panel described in Japanese Patent No. 2940467 does not perform the above-described extreme cooling, but applies cold air while the glass is cooled from the annealing point to the strain point. Provided by weak reinforcement. That is, while the conventional air-cooling method blows air on a glass having a softening point of about 700 ° C., Japanese Patent No. 2940467
The physically tempered glass panel of No. 1 will be exposed to air at a temperature of about 500 ° C. at the annealing point. Therefore, although the tensile stress inside the glass is small, the compressive stress on the surface is also small and the bending strength is low. Specifically, the compressive stress is 5-30 MPa, the tensile stress is 2-15 MPa, and the bending strength is 100-15.
0 MPa. With a glass having a bending strength of about 100 to 150 MPa, the thickness of the glass must be increased in order to receive the pressure difference between the inside and outside of the CRT, and the glass becomes thick and heavy. Further, as for the molding of the glass panel, a manufacturing method is generally employed in which a skirt portion is formed simultaneously with a flat portion by pressing a glass gob. However, in the physically strengthened product, the pressed high-temperature glass must be quenched or the cooling rate must be intentionally distributed, so that a difference occurs in the shrinking rate and the glass is easily deformed. Therefore, the molding yield is low and the cost is high.

In addition, the physical strengthening method is suitable for strengthening a thick glass rather than a thin glass because the profile of a formed stress-strain layer (including a compressive stress layer) is gentle. High stress strain layer cannot be secured,
It is difficult to obtain high strength. As a result, it is difficult to reduce the thickness of the glass panel by physical strengthening, and the weight reduction of the glass panel cannot be expected. Patent No. 2672
Since the strain point of the physically strengthened glass described in No. 766 is about 470 ° C., when the glass is heated to about 450 ° C. in the frit sealing process, it may be partially and temporally exposed to a higher temperature, and the stress strain is reduced. It was relaxed, and there was a possibility that the desired bending strength could not be obtained. Further, Patent No. 267
The panel glass described in No. 1766 has a Young's modulus of about 76 GPa, and when the thickness of the panel is reduced, the panel glass is pressed by the atmospheric pressure and easily deformed.

On the other hand, as described in Japanese Patent No. 2904067, a chemically strengthened glass has a thin stress-strain layer and is vulnerable to damage. Therefore, a CRT panel in which the outside is at atmospheric pressure and the inside is vacuum is always used. It has been considered unusable because of external stress. That is, in the CRT, the stress-strained layer of the chemically strengthened glass can only have a thickness of 10 to 30 μm.
It was not able to withstand the wound test.

Further, a technique for changing the alkali ion concentration of the surface layer of the glass panel by ion exchange has been known for the purpose of preventing coloring (browning) of the glass panel for a cathode ray tube due to electron beam irradiation. For example, JP-A-50-105705 discloses that lithium or sodium present in a surface layer to be irradiated of an electron beam is ion-exchanged with at least one of potassium, rubidium, cesium and hydrogen. A method for producing an electron beam irradiated glass in which lithium or sodium present in a glass surface layer is reduced to prevent browning is described. In addition,
Japanese Patent No. 108797 describes a glass panel which is irradiated with an electron beam in which at least sodium ions on the surface of a soda lime silica glass panel to which the electron beam is irradiated are replaced with potassium ions and lithium ions. The penetration depth of the substituted lithium ions is 1
0 μm, penetration depth of substituted potassium ions is 5-2
It is described that the thickness is preferably 0 μm, and when it is shallower or deeper, the browning effect is reduced. However, the soda lime silica glass has a Young's modulus of about 73 GPa, and is easily deformed when the panel is made thin.

In a shape such as a flat cathode ray tube (for example, a flat cathode ray tube) in which a glass panel portion for a cathode ray tube which has recently appeared is made of flat glass, unlike a conventional curved glass panel, it receives the atmospheric pressure in a flat surface. Therefore, a higher strength is required for the glass itself, and sufficient strength cannot be obtained only by replacing ions for the purpose of preventing browning as described above. For this reason, in the current situation, the flat cathode ray tube has to be thicker than the conventional curved cathode ray tube.
Note that none of the above-described methods of ion exchange for the purpose of preventing browning are intended for applications such as a flat-panel cathode ray tube, and moreover, they are not intended to realize a thin and light-weight flat cathode-ray tube. There is no need to gain strength.

Further, attempts have been made to form the funnel from thin metal instead of glass in order to reduce the weight. Conventionally, a frit seal mainly composed of low-melting glass has been used for joining a funnel and a panel. However, the joining strength of a metal funnel is low, and there is a concern about vacuum breakage.

[0010]

Heretofore, no study has been made on the composition of the glass and the properties of the glass necessary for realizing a thin and lightweight glass panel for a cathode ray tube. Conventionally, the thickness is increased in order to obtain sufficient strength, and a glass panel for a cathode ray tube which has achieved the level of thinness and weight reduction referred to in the present invention has not yet been developed.

The present invention has been made under the above-mentioned background, and an object of the present invention is to provide a glass for a cathode ray tube, a glass panel for a cathode ray tube, a cathode ray tube, and a method for manufacturing the same, which can realize a reduction in thickness and weight. Aim.

[0012]

In order to achieve the above object,
As a result of intensive studies, it has been found that even if the glass for a cathode ray tube having a conventionally known composition is sufficiently chemically strengthened, it is difficult to achieve a reduction in thickness and weight. The inventor has
Bending strength is higher than conventional (300MPa or more, especially 500MPa or more) to realize thinning and lightening.
Glass for cathode ray tubes was developed first. However, even if the bending strength is increased, the inside of the cathode ray tube is kept in a vacuum and the atmospheric pressure is always applied from the outside.In particular, in the case of a flat CRT glass panel, the thinner the plate thickness, the more the inside and outside pressure of the glass It has been found that the image tends to bend due to the difference and to be distorted. Further, in order to further develop a cathode ray tube glass having both a higher bending strength and a higher Young's modulus than in the past, and to achieve a reduction in thickness and weight, it is not enough to have a high bending strength alone. Above (especially 9
5 GPa or more). Further, the present inventors have found out characteristics such as bending strength, specific elastic modulus (Young's modulus / specific gravity), thickness of the stress-strain layer, and strain point necessary for realizing a thin and lightweight glass panel for a cathode ray tube. It was completed. Heretofore, characteristics such as bending strength and Young's modulus of glass for reducing the thickness and weight of a glass panel for a cathode ray tube have not been studied at all.

Such a glass for a cathode ray tube is, for example,
It is used as a glass panel for a cathode ray tube which needs to have a mechanical strength to receive an external pressure such as an atmospheric pressure or a load, and also needs to shield X-rays. In particular, it is suitable for applications such as flat display panels such as flat-panel cathode ray tubes, field emission displays, and plasma displays.

The present invention has the following configuration.

(Constitution 1) A glass for a cathode ray tube, which is made of chemically strengthened glass and has a Young's modulus of 90 GPa or more.

(Structure 2) The glass for a cathode ray tube according to Structure 1, wherein the specific elastic modulus (Young's modulus / specific gravity) is 30 GPa or more.

(Structure 3) The glass for a cathode ray tube according to Structure 1 or 2, wherein the strain point is 500 ° C. or higher.

(Structure 4) SiO ₂ , Al ₂ O ₃ , Li ₂ O,
It is obtained by chemically strengthening a base glass containing Na ₂ O, SrO, TiO ₂ , ZrO ₂ , and CeO ₂ and containing one or more oxides selected from the group consisting of MgO and CaO. The glass for a cathode ray tube according to any one of Configurations 1 to 3, characterized in that:

(Arrangement 5) SiO ₂ , Al ₂ O ₃ , Li ₂ O,
Na ₂ O, SrO, TiO ₂ , ZrO ₂ , CeO _2, and one or more oxides selected from the group consisting of MgO and CaO, and Li ₂ O, Sr
O, with the mole percent content of _{ZrO 2, Li 2 O 5~20%} , SrO 3~15%, for a cathode-ray tube matrix glass, wherein the ZrO ₂ 0.1 to 5%, it is.

(Structure 6) SiO ₂ , Al ₂ O ₃ , Na ₂ O,
TiO _2, MgO, with the mole percent content of _{CaO, SiO 2 40~70%, Al} 2 O 3 0.1~15%, Na 2 O 0.1~10%, 0~15% MgO, CaO 0 -15%, TiO ₂ 0.1-15%, and S
iO ₂ + Al ₂ O ₃ + Li ₂ O + Na ₂ O + SrO + TiO ₂
The base material glass for a cathode ray tube according to Configuration 5, wherein the total amount of + ZrO ₂ + MgO + CaO + CeO ₂ is 85 mol% or more.

(Structure 7) In addition to the above glass components, mol%
And BaO, ZnO, La_TwoO_Three, Cs _TwoO, P_TwoO_Five, B_Two
O_Three, Y_TwoO_Three, Nb_TwoO_Five, Sb_TwoO_Three, SnO_Two, K_TwoO and
One or more glass components selected from the group of
Configuration 5 or 6 characterized by containing less than 15 mol% in amount
The base material glass for a cathode ray tube according to the above.

(Structure 8) In addition to the above glass components, mol%
The cathode ray tube according to any one of the constitutions 5 to 7, wherein the composition contains at least 1 mol% or less selected from oxides of Ni, Co, Fe, Mn, V, Cu and Cr. Base glass.

(Configuration 9) A glass for a cathode ray tube obtained by chemically strengthening the base glass for a cathode ray tube according to any one of the configurations 5 to 8.

(Structure 10) The glass for a cathode ray tube according to Structure 9, wherein one or more conditions described in any one of Structures 1 to 3 are satisfied.

(Structure 11) The base material glass for a cathode ray tube according to any one of Structures 5 to 8 is ion-exchanged in a treatment bath containing Na ions and / or K ions heated to 350 to 550 ° C. to chemically strengthen it. A method for producing glass for a cathode ray tube, characterized by comprising:

(Constitution 12) A glass panel for a cathode ray tube comprising the glass for a cathode ray tube according to any one of the constitutions 1 to 4, 9 and 10.

(Structure 13) The glass panel for a cathode ray tube according to structure 12, wherein the thinnest portion has a thickness of 1/200 to 1/50 of the length of the diagonal line.

(Structure 14) The glass panel for a cathode ray tube according to structure 12 or 13, wherein the glass panel is used for a flat cathode ray tube.

(Structure 15) In the method for manufacturing a glass panel for a cathode ray tube, a step of processing the base material glass for a cathode ray tube according to any of Structures 5 to 8 into a panel shape, Ion exchange in a treatment bath containing Na ions and / or K ions heated to ５550 ° C. to chemically strengthen the glass panel for a cathode ray tube.

(Structure 16) A cathode ray tube comprising the glass panel for a cathode ray tube according to any one of structures 12 to 14.

(Structure 17) A method for manufacturing a cathode ray tube, comprising a step of heating and integrating the glass panel for a cathode ray tube according to any one of Structures 12 to 14 and a funnel by frit sealing.

(Structure 18) A glass panel for a cathode ray tube, comprising a chemically strengthened glass having a compressive stress layer formed by ion exchange, wherein a tensile stress inside the glass is less than 20 MPa.

(Structure 19) The glass panel for a cathode ray tube according to Structure 18, wherein the surface tempering stress of the chemically strengthened glass is 100 MPa or more.

(Structure 20) After molding the molten glass, cut it,
A method for manufacturing a glass panel for a cathode ray tube, wherein chemical strengthening is performed after at least one of heat bending, polishing, and metal bonding.

(Structure 21) The method for manufacturing a glass panel for a cathode ray tube according to Structure 20, wherein the forming of the molten glass is float forming.

(Structure 22) A method for manufacturing a glass panel for a cathode ray tube, wherein a metal joint for joining with a metal funnel is formed by burying the glass while heating and softening the glass.

(Structure 23) A method for producing a glass panel for a cathode ray tube, wherein a voltage is applied to a molten salt and a glass panel in an ion exchange treatment bath to perform ion exchange.

(Structure 24) A method for manufacturing a glass panel for a cathode ray tube, comprising removing alkali ions and / or hydronium ions from the surface of a glass substrate after chemical strengthening.

In the present invention, "glass panel"
May be referred to as “panel glass”, and both are synonymous.

[0040]

According to the above configuration 1, since the Young's modulus is 90 GPa or more, it is difficult to bend and the plate thickness can be reduced. When the Young's modulus is less than 90 GPa, it is easily deformed by receiving an external pressure such as an atmospheric pressure or a load, and is easily deformed. In particular, when the thickness of a glass panel for a flat-panel cathode ray tube or the like is reduced (for example, 1/200 to 1/50 of the length of the diagonal line), the glass may bend, and the image may be distorted. . As described above, conventionally, the thickness is increased in order to obtain a sufficient strength, and a thin glass panel for a cathode ray tube has not yet been developed. Conventionally, a glass for a cathode ray tube having a sufficient strength capable of being thinned has not been developed.
Since only glass of about Pa was obtained, it was difficult to confirm and predict how much the Young's modulus had to be realized to achieve thinning. The present inventor has developed a glass for a cathode ray tube in which both the bending strength and the Young's modulus are larger than in the past, in order to realize a reduction in thickness and weight, and in order to realize a reduction in thickness and weight, the bending strength is required. It has been found that it is not enough to be just large, and that the Young's modulus needs to be 90 GPa or more. Thus, in the present invention, the Young's modulus is an important factor for preventing deformation due to external pressure. The glass for a cathode ray tube of the present invention has 90 GPa.
Because it has the above Young's modulus, it is difficult to bend even if it is thin,
Therefore, even a thin panel can be kept flat. In particular, this is the first realization of a thinner flat panel glass panel for a cathode-ray tube.

When the Young's modulus is 90 GPa or more and the bending strength is 300 MPa or more (especially 500 MPa or more), the sheet thickness can be reduced while maintaining the pressure resistance (load resistance) of the glass for a cathode ray tube. It is preferred.

According to the above configuration 2, since the specific elastic modulus (Young's modulus / specific gravity) is 30 GPa or more, the glass can be made thinner and lighter in weight. Young's modulus and flexural strength alone are not enough to make glass thinner and lighter in weight. This is because, even if the strength of the glass is high, if the specific gravity is increased by that amount, the merit of reducing the weight is reduced. The present inventor, when the specific elastic modulus, which is a function of Young's modulus and specific gravity, is 30 GPa or more,
It has been found that the glass can be made thinner and lighter. When the specific elastic modulus is less than 30 GPa, the effect of weight reduction is small.

According to the above configuration 3, even when the heat treatment is performed, the stress distortion is alleviated and the strength does not decrease. For example, in a manufacturing process of a cathode ray tube, there is a step of joining a glass panel and a funnel glass by heating the glass panel to about 450 ° C. using a frit. Since the strain point of the glass for a cathode ray tube of the present invention is 500 ° C. or more, stress distortion is relaxed in a heating step such as a frit seal, so that the strength does not decrease. Therefore, it is suitable for applications requiring strength and performing heat treatment. In order to realize a flat and thin CRT panel that is thinner and lighter, it is necessary to satisfy all the conditions of the above configurations 1 to 3.

According to the above configuration 4, by including these components, a high Young's modulus can be obtained, high strength (bending strength, Knoop hardness, etc.) can be easily obtained by ion exchange, and high X-ray absorption characteristics can be obtained. Thus, it is possible to obtain a glass for a cathode ray tube that satisfies one or more conditions of the above-described configurations 1 to 3.

According to the glass described in the above configuration 5, by containing these components, the glass has a high Young's modulus and a high X-ray absorption characteristic, and has high resistance to coloring of the glass by electron beam irradiation (electron beam irradiation). ), And high strength (bending strength, Knoop hardness, etc.) can be easily obtained by ion exchange, and a base material glass for a cathode ray tube suitable for chemical strengthening can be obtained. In particular, the glass described in Structure 5 has the following effects. By including li ₂ O 5 to 20 mol%, the ion exchange is facilitated. By setting the SrO content to 3 to 15 mol%, it is possible to enhance the X-ray absorption and prevent the Young's modulus and the bending strength from decreasing. The ZrO ₂ 0.1~5 mol%
By containing, the X-ray absorption coefficient and the Young's modulus are improved.
In addition, it is preferable to further contain CeO _{2 in an amount} of 0.01 to 1 mol%, because coloring (browning) due to an electron beam can be prevented.

According to the glass described in the constitution 6, the constitution 4
In addition to the effects described above, the following effects are provided. By including these components in predetermined amounts, higher Young's modulus can be achieved.
By including Al ₂ O ₃ , Li ₂ O, and Na ₂ O in a well-balanced manner, higher strength (bending strength, Knoop hardness, etc.) can be obtained by ion exchange. SrO, TiO ₂ , ZrO ₂ , Ca
Since a predetermined amount of O and MgO is contained, the X-ray absorption coefficient can be further increased. Note that the glass described in the configuration 6 can satisfy all the conditions of the above configurations 1 to 3. SiO
₂ + Al ₂ O ₃ + Li ₂ O + Na ₂ O + SrO + TiO ₂ + Z
The total amount of rO ₂ + MgO + CaO + CeO ₂ is preferably at least 85 mol%, more preferably at least 90 mol%.

According to the above-mentioned constitution 7, by adding these components, improvement of meltability, clarification, improvement of devitrification resistance,
To facilitate the production of glass and adjust its properties, such as adjusting the viscosity of glass, adjusting the coefficient of thermal expansion and X-ray absorption coefficient, adjusting the Young's modulus, adjusting the ion exchange rate, preventing solarization, and preventing browning. Can be. The total amount of these components is preferably less than 15 mol%, more preferably less than 10 mol%.

According to the above configuration 8, by adding these components, the transmittance of the glass can be adjusted, and the contrast can be improved and the color of the screen can be corrected. Usually, glass panels for cathode ray tubes are made of NiO, Co
A glass whose transmittance is intentionally lowered by adding ₂ O ₃ or the like is used. When the glass panel is made thinner, the transmittance increases and the contrast decreases. For this reason, when thinning a glass panel, it is important to add these components in necessary amounts.
The content of at least one component selected from these oxides is preferably 1 mol% or less, more preferably 0.1 mol% or less.

According to the ninth aspect, a glass for a cathode ray tube obtained by chemically strengthening the base glass for a cathode ray tube according to any one of the fifth to eighth aspects is obtained.

According to the above configuration 10, a glass for a cathode ray tube which satisfies at least one of the above-mentioned constitutions 1 to 3 can be obtained.

According to the above configuration 11, a glass for a cathode ray tube having high strength can be manufactured by ion exchange. Therefore, a thin glass for a cathode ray tube can be obtained without reducing the strength.

According to the glass panel for a cathode ray tube described in the twelfth aspect, the following effects can be obtained. First, since the glass itself has a high Young's modulus, it is possible to obtain a glass panel for a cathode ray tube that is hardly bent. Then, even when a force is applied to the panel surface due to a difference in pressure between the inside and outside of the cathode ray tube, the panel surface is unlikely to be bent, so that image distortion can be reduced. Second, since the glass itself has high Young's modulus and bending strength, the thickness of the glass panel for a cathode ray tube can be reduced while maintaining pressure resistance (load resistance). Third, not only the strength is high but also the depth of the compressive stress layer is substantially 50 μm or more, so that the wound strength can be increased. Accordingly, a thin and light glass panel for a cathode ray tube can be obtained without reducing the strength. Fourth, even when a cathode ray tube is manufactured by heating and bonding a glass panel for a cathode ray tube and a funnel with a frit seal, the panel can be made thin, so that a panel which is hard to be damaged by a rapid temperature change can be obtained. Can be. Therefore, when manufacturing the cathode ray tube, the speed of heating and cooling before and after the frit sealing step can be increased, so that the productivity of the cathode ray tube can also be increased. Fifth, since the glass panel chemically strengthened by ion exchange has a high surface hardness, it is hardly damaged, and a glass panel for a cathode ray tube which is hardly damaged by the scratch in combination with the depth of the compressive stress layer can be obtained. That is, the glass of the present invention has a stress-strain layer of 5
Since the thickness is 0 μm or more, the strength of the glass is not easily reduced even if the glass surface is scratched. For example, the bending strength when the glass surface is scratched with a # 150 sandpaper, that is, the scratching strength is 250 MPa or more. Therefore, it has high resistance to scratches on glass during the manufacturing process or use of the cathode ray tube, and is suitable as a glass panel for a cathode ray tube.

According to the above configuration 13, if the thickness of the thinnest portion is 1/200 to 1/50 of the length of the diagonal,
The bending of the panel due to the pressure difference can be reduced. The thickness of the thinnest part is 1 / 200-1 / 1/1 of the diagonal length
If it is less than 50, the bending of the panel due to the pressure difference may not be reduced.

According to the above configuration 14, the above configurations 12 to 1
A glass panel for a flat cathode ray tube having the effect described in 3 is obtained. In other words, the above-described effect is exhibited in a flat panel having a shape that is less resistant to a force applied to the panel when formed into a cathode ray tube than a conventional curved shape.

According to the above configuration 15, a glass panel for a cathode ray tube including the glass panel for a cathode ray tube having the effects described in the above configurations 5 to 8 can be manufactured.

According to the above configuration 16, the above configurations 12 to 1
A cathode ray tube provided with a glass panel for a cathode ray tube having the effect described in 4 is obtained.

According to the above configuration 17, the above configurations 12 to 1
The cathode ray tube provided with the glass panel having the effect described in 4 can be manufactured.

According to the above configuration 18, since the stress-strain layer is formed on the surface of the glass panel by ion exchange, the entire surface can be uniformly strained. Therefore, warpage and undulation are very small. Further, the tensile stress inside the glass (the portion where the tensile stress is maximized in the physically strengthened glass (the central portion in the thickness direction of the glass)) is less than 20 MPa, and the possibility of self-destruction is small.

According to the above configuration 19, the compressive stress formed on the surface is 100 MPa or more, and the bending strength is large. Therefore, the thickness of the glass can be reduced to obtain the pressure resistance, and as a result, a light-weight glass panel and a cathode ray tube can be manufactured. In this case, the thickness of the stress-strain layer formed on the surface can be set to 50 μm or more, and the strength is not significantly reduced due to a scratch in a manufacturing process or practical use.

The present inventor has found that a predetermined chemically strengthened glass satisfying the predetermined characteristics described in the constitutions 18 and 19 can solve the problem described in the above-mentioned Japanese Patent No. 2940067. The predetermined chemically strengthened glass is obtained by developing and optimizing a chemical strengthening method (condition) or a chemical composition so as to satisfy these predetermined characteristics. Further, the predetermined chemically strengthened glass is a CRT.
However, the present invention is not limited to this, and can be applied to a display exposed to a pressure caused by a pressure difference between inside and outside, for example, a panel glass of a field emission display (FED) or a plasma display (PDP). Needless to say, a glass panel that satisfies the characteristics of the above structures 1 to 3 in addition to the characteristics of the above structures 18 to 19 is preferable.

According to the above configuration 20, a glass panel can be manufactured from a plate-like glass by these steps, so that the molding yield and production tact are high and the cost is low. On the other hand, the above-described method of manufacturing a glass panel by simultaneously molding a skirt portion together with a flat portion by press molding has a low molding yield and high cost.

According to the above configuration 21, since the molten glass is formed by float forming, a glass panel with high productivity and low cost can be manufactured.

According to the above construction 22, the metal joint for joining with the metal funnel is buried in the plate-like glass while heating and softening the glass, and the metal funnel and the metal joint are joined by welding or the like. Therefore, the joining strength is increased as compared with the joining using the conventional frit seal.

According to the above configuration 23, even when a base glass having a composition other than the optimum composition described in the above configurations 5 to 8 is used, the moving velocity of the movable ions can be obtained by applying a voltage to the glass panel and the molten salt. And the ion exchange rate can be increased. As a result, at least the above configuration 1
A glass panel satisfying the characteristics of 8 to 19 can be manufactured, or a glass panel satisfying the characteristics of the above structures 1 to 3 in addition to the characteristics of the above structures 18 to 19 can be manufactured.

According to the above configuration 24, by removing alkali ions and / or hydronium ions from the glass substrate surface after the chemical strengthening, it is possible to improve the chemical durability of the glass surface, and at the same time, to improve the coloring by the electron beam. Can be expected to have the effect of suppressing

[0066]

BEST MODE FOR CARRYING OUT THE INVENTION A preferred composition range (unit is mol%) of a base glass for a cathode ray tube according to the present invention will be described.

SiO ₂ is a basic component of glass.
%, The devitrification resistance and chemical durability deteriorate. Conversely 7
If it exceeds 0%, melting becomes difficult. Therefore, the content of SiO ₂ is limited to 40 to 70%. Preferably 45-6
0%, and more preferably 50 to 55%.

Al ₂ O ₃ is a component for improving the devitrification resistance, chemical durability and ion exchange efficiency of glass.
If it is less than 0.1%, the effect is not obtained, and if it exceeds 15%, the devitrification resistance deteriorates. Therefore, the content of Al ₂ O ₃ is 0.1.
Limited to 1-15%. Since Al ₂ O ₃ is also a component that lowers the X-ray absorption coefficient, it is preferably 1 to 10%, more preferably 1 to 5%.

Li ₂ O is a component for chemically strengthening the glass by being ion-exchanged mainly with Na ions in the ion-exchange treatment bath at the surface layer of the glass. %, The devitrification resistance and chemical durability decrease. Therefore, the content of Li ₂ O is 5 to 5.
Limited to 20%. Since Li ₂ O is also a component that lowers the X-ray absorption coefficient, it is preferably 7 to 18%, more preferably 10 to 15%.

Na ₂ O is a component for chemically strengthening the glass and preventing browning by being ion-exchanged mainly with K ions in the ion exchange treatment bath at the glass surface layer. Less than 0.1% has no effect and 10%
If it exceeds 300, the devitrification resistance and the chemical durability decrease. Therefore, the content of Na ₂ O is limited to 0.1 to 10%. Since Na ₂ O is also a component that lowers the X-ray absorption coefficient, it is preferably 1 to 5%.

MgO is a component for improving the Young's modulus of the glass, and can be contained in the range of 0 to 15%. If it exceeds 15%, the X-ray absorption coefficient decreases. Therefore, the content of MgO is limited to 0 to 15%. The preferred content is 5 to 10%.

CaO is a component for improving the X-ray absorption coefficient and Young's modulus of the glass, and can be contained in the range of 0 to 15%. If it exceeds 15%, the liquidus temperature rises. Therefore, the content of CaO is limited to 0 to 15%.
The preferred content is 5 to 10%.

SrO is a component that plays an important role in the glass of the present invention. SrO is a component that has a remarkable effect of increasing the X-ray absorption coefficient, but it has been found that the addition of SrO does not significantly lower the Young's modulus or bending strength.
If it is less than 3%, the X-ray absorption coefficient is less than 28, and conversely 15%
If it exceeds, the devitrification resistance is reduced. Therefore, the content of SrO is limited to 3 to 15%. Preferred content is 5 to 13
%.

BaO, which is an optional component, is a component that improves the X-ray absorption coefficient of glass, and therefore can be contained. However, BaO has the effect of increasing the X-ray absorption coefficient,
Since the content of BaO is about half of rO and a component that lowers the Young's modulus, the preferable content of BaO is 0 to 5%.

Although ZnO, which is an optional component, has a great effect of increasing the X-ray absorption coefficient, it reduces the flexural strength and Young's modulus, so that it is preferably less than 5%.

TiO ₂ is a component that improves the Young's modulus and X-ray absorption coefficient of glass and prevents coloring by electron beams. If it is less than 0.1%, the effect is not obtained, and if it exceeds 15%, the devitrification resistance is reduced. Therefore, the content of TiO ₂ is limited to 0.1 to 15%. The TiO ₂ absorbs short wavelength range of the light transmitted through the glass, so easily colored, preferable content is from 0.1 to 5%.

ZrO _{2 is} also one of the components that play an important role in the glass of the present invention. ZrO ₂ is a component that improves the Young's modulus, X-ray absorption coefficient and bending strength of glass. If it is less than 0.1%, the effect is not obtained. On the contrary, if it exceeds 5%, unmelted glass tends to be generated. The content of ZrO ₂ is limited to 0.1% to 5%. The preferred content is 1-3%.

CeO ₂ which is an optional component is a component which prevents coloring (browning) by an electron beam. The preferred content is 0.01-1%.

K ₂ O, which is an optional component, can be contained in the base glass in order to prevent coloring (browning) due to an electron beam. The preferred content is 0 to 5%.

In addition, La ₂ O ₃ , Cs ₂ O, P ₂ O ₅ , B ₂
One or more of O ₃ , Y ₂ O ₃ , Nb ₂ O ₅ , Sb ₂ O ₃ , SnO _2, F and the like may be used to improve melting property, clarification, improvement of devitrification resistance, and viscosity of glass. , Adjustment of thermal expansion coefficient and X-ray absorption coefficient, adjustment of Young's modulus, adjustment of ion exchange rate, prevention of solarization, prevention of browning, etc. can do.

Further, Ni, Co, Fe, Mn, V, C
At least one selected from oxides such as u and Cr can be appropriately added for the purpose of adjusting the transmittance of glass.

The glass for a cathode ray tube of the present invention is made of P
It does not substantially contain bO. This is because the use of PbO is environmentally unfavorable, and PbO is a component that deteriorates chemical strengthening and a component that lowers Young's modulus.

More preferred composition 1 is composed of a base glass component and
And in mole%, SiO_Two 50-60%, Al_TwoO_Three 1-10%, Li_TwoO 10-20%, Na_TwoO 0.1-8%, CeO_Two 0.01-1%, MgO 1-10%, CaO 1-10%, SrO 5-10%, TiO_Two 0.1-5%, ZrO_Two 1 to 5%, containing
In this composition, Al _TwoO_ThreeIs preferably 1-5%
No. The advantage of the above composition 1 is that SiO 1_TwoTiO2_Two
In the above composition range 1 with a small amount, the Young's modulus is 95 GPa or less.
Above, bending strength of 400 MPa or more, and excellent devitrification resistance
Glass with high SrO content
The higher the X-ray absorption coefficient
It is.

More preferred composition 2 is composed of a base glass component and
And in mole%, SiO_Two 40-50%, Al_TwoO_Three 1-10%, Li_TwoO 7-15%, Na_TwoO 0.1-8%, CeO_Two 0.01-1%, MgO 1-10%, CaO 1-10%, MgO + CaO 10-30%, SrO 5-15%, TiO_Two 5-15%, ZrO_Two 1 to 5%, containing
In this composition, Al _TwoO_ThreeIs preferably 1-5%
No. The advantage of composition 2 is that TiO_TwoAbove composition often
In the range 2, the Young's modulus is 100 GPa or more, and the bending strength is 40.
0 MPa or more can be obtained, SrO content
The X-ray absorption coefficient can be increased as
That is.

The feature of the above composition range 1 is that the devitrification resistance and the ease of molding are superior to the above composition range 2. The feature of the composition range 2 is that the Young's modulus is larger than the composition range 1.

The glass of the preferred composition in the above-described embodiment, more preferably composition 1 and composition 2, has a Knoop hardness of 600 GPa or more (particularly 650 GPa or more) on the glass surface after chemical strengthening. Since the Knoop hardness is large, the chemical strengthening not only can prevent the growth of surface flaws but also can prevent the occurrence of deep flaws.

The method for producing the glass of the present invention is not particularly limited, and a conventionally used method can be used. For example, oxides, hydroxides, carbonates, nitrates, chlorides, sulfides, and the like are appropriately used as glass raw materials, weighed to have a desired composition, and mixed to obtain a mixed raw material. This is put in a heat-resistant crucible (crucible), melted at a temperature of about 1300 to 1500 ° C., stirred and clarified to obtain a homogeneous molten glass. The glass is then cast into a forming frame to form a glass block, form a sheet, or press form into a cathode ray tube (CRT) shape. Transfer to a heated furnace near the annealing point of the glass and cool to room temperature. The glass block obtained by slow cooling is subjected to slicing, polishing, etc., the sheet-formed glass is subjected to cutting, polishing, hot bending and the like as necessary, and the press-formed glass is also subjected to polishing as necessary. You.

The polished glass is subjected to ion exchange in an alkali molten salt. Regarding this step, the same technique as the conventional ion exchange step of chemically strengthened glass is used.
The composition of the molten salt is selected according to the glass composition.
After being immersed in the molten salt for a predetermined time, it is taken out and washed. In addition, ion exchange between alkali metal ions can be uniformly performed by immersion in a molten salt, which is preferable because it is excellent in mass productivity and a glass having a stable compressive stress layer can be provided at low cost. In addition, since the compressive stress layer is formed by ion exchange, the compressive stress layer can be efficiently formed even with thin glass, and since it does not depend on the shape, it can be easily strengthened even for a cathode ray tube panel having a complicated shape. It is preferable because it is possible. Further, when the glass is subjected to a heat treatment, the compressive stress is hardly reduced unlike the physically strengthened glass, and the strength of the glass is hardly reduced. Further, by ion-exchanging the base material glass for a cathode ray tube containing both Li ₂ O and Na ₂ O in a well-balanced manner with a molten salt containing both sodium ions and potassium ions,
Lithium ions in the glass are exchanged with sodium ions in the molten salt, and sodium ions in the glass are exchanged with potassium ions in the molten salt, so that sufficient strength is obtained, which is preferable. In particular, in the present invention, the ion-exchanged glass replaces lithium ions and sodium ions contained in the base glass with sodium ions and potassium ions by ion exchange, respectively. Since lithium ions are mixed depending on the ion and the degree of ion exchange, the effect of preventing coloring that occurs when the glass is irradiated with an electron beam is large.

The thickness of the stress-strain layer can be determined by a Babinet correction method using a precision strain meter, a method using a polarizing microscope, or the like. For the Babinet correction method using a precision strain meter, a commercially available measuring device may be used. In the method using a polarizing microscope, first, the glass sample is cut perpendicularly to the ion exchange surface, the cross section is polished thinly to a thickness of 0.5 mm or less, and polarized light is incident perpendicularly to the polished surface with a polarizing microscope. Observe with direct Nicol. In the chemically strengthened glass, a stress-strain layer is formed in the vicinity of the surface, so that the thickness of the strain layer can be measured by measuring the distance from the surface to the portion where the brightness or color is changing.

The difference between chemically strengthened glass and physically strengthened glass can be understood by examining the distribution of metal ions contained near the glass panel surface. Specifically, the depth distributions of a metal ion having a larger ionic radius (eg, an alkali metal ion) and a metal ion having a smaller ionic radius (eg, an alkali metal ion) are examined. (The density of metal ions having a larger ionic radius) / (the density of metal ions having a smaller ionic radius) is closer to the surface than to a deep portion of the glass (for example, a portion having a depth of half the thickness of the glass). If the flexural strength is within the range of the present invention, it can be understood that chemical strengthening by ion exchange has been performed.

When the metal ions (typically, alkali metal ions) in the glass surface layer are exchanged for metal ions having a larger ionic radius (typically, alkali metal ions), the stress-strain layer becomes Large ions enter while shrinking the glass structure, so that compressive stress is generated near the surface. The range to which this stress reaches is called a compressive stress layer. Since it is a strained layer to the last, compressive stress is relaxed by heat treatment (depending on time) above the strain point of glass. The stress-strain layer includes a tensile stress layer. As described above, since the stress-strained layer is a strained layer to the last, compressive stress is relaxed by heat treatment (depending on the processing time) at a temperature higher than the strain point of glass.
The stress-strain layer formed by the chemical strengthening is hardly relieved, and the strength of a panel for a cathode ray tube requiring heat treatment is not significantly reduced.

[0092]

The present invention will be further described with reference to the following examples. (Examples 1 to 8, Reference Example 1, Comparative Example 1) Raw materials such as oxides, hydroxides, carbonates, nitrates, chlorides, and sulfates are shown in Table 1.
The blended raw materials weighed and mixed so as to have a composition of ~ 2,
The mixture was placed in a heat-resistant container such as a platinum crucible, heated at 1400 ° C., melted, stirred, homogenized and clarified, and then poured into a mold. After the glass solidified, it was then transferred to an electric furnace that had been heated near the annealing point of the glass, and was gradually cooled to room temperature. From the obtained glass block, a double-sided polished sample of 65 × 10 × 1 mm was prepared and subjected to ion exchange. The composition of the molten salt was NaNO ₃ : KNO ₃ (weight ratio) = 2: 3. 380
The glass sample was immersed in a molten salt kept at ４460 ° C. for a predetermined time, then taken out and washed. Tables 1 and 2 show the glass composition and various measurement data.

The X-ray absorption coefficient was such that X-rays having a wavelength of 0.06 nm were incident on the produced glass,
This is a value obtained by measuring the transmitted dose at a position separated by mm and calculating the absorption coefficient. The thickness of the stress-strain layer was measured by polishing a cross section of the test piece and using a polarizing microscope. The bending strength of the ion-exchanged sample was measured according to the three-point bending test of JIS-R1601. The abrasion strength was measured by applying a load so that the glass surface of the ion-exchanged sample was evenly scratched with a # 150 sandpaper and a tensile stress was applied to the surface.
A point bending test was performed.

[0094]

[Table 1]

[Table 2]

The glasses of Examples 1 to 8 had an X-ray absorption coefficient of 28 cm ^-1 or more, a Young's modulus of 90 GPa or more, a specific elastic modulus of 30 GPa or more, a bending strength of 400 MPa or more, and a stress-strain layer (compression stress layer). ) Is 50 μm or more. The wound strength is 250 MPa or more. On the other hand, the glass of Reference Example 1 and Comparative Example 1 had a Young's modulus of 80.
Since it is less than GPa and the X-ray absorption coefficient is less than 20 cm ^-1, it is not suitable for glass for cathode ray tubes or glass for flat displays. It should be noted that any of the glasses described in the publications cited as prior art are outside the range of the glass composition of the present invention, and thus do not satisfy the properties of the glass of the present invention.

(Example 9 and Comparative Example 2) A conventional untempered glass for a cathode ray tube having a composition shown in Table 3 was 65 × 10 × 5 m.
m and 65 × 10 × 10 mm (Comparative Example 2). On the other hand, the glass having the composition of Example 1 was processed into the same shape and subjected to ion exchange under the conditions shown in Table 1 (Example 9). These breaking loads were measured by a three-point bending test with a span of 50 mm. Table 4 shows the results. As shown in Table 4, the load-bearing capacity conventionally realized by setting the thickness of the glass to 10 mm as in Comparative Example 2 can be sufficiently obtained with the glass of Example 9 at half the thickness. I have. Therefore, similarly, in the case of an actual product, the thickness of the glass, which is conventionally required due to the restriction of the pressure resistance, can be reduced, and the product can be reduced in weight.

[0097]

[Table 3]

[Table 4]

(Example 10) Table 1 shows a sheet glass having the composition of Example 1 (thickness: 10 mm, thickness of the thinnest portion: 8 mm).
Was performed under the conditions described above to prepare a 36-inch flat panel glass panel for a cathode-ray tube. Its weight is about 20 kg, which is lighter than the conventional about 40 kg. Further, the thickness can be reduced as compared with the conventional thickness of 20 mm or more. Furthermore, it was confirmed that even a large size had sufficient strength. Next, the glass panel for a plane cathode ray tube and the funnel were heated and integrated by a frit seal to obtain a 36-inch plane brown. Then, it was confirmed that the glass did not bend due to the pressure difference between the inside and outside, and the image was not distorted. In addition, it was confirmed that coloring (browning) of the glass panel did not occur.

Example 11 Glass having the composition shown in Table 5 was press-molded into a panel shape, and the glass was maintained at 380 ° C. as shown in FIG. 1 by NaNO ₃ : KNO ₃ (weight ratio) = 2. : 3 was immersed in the molten salt so that the joint with the funnel came out above the liquid level. Electrodes were arranged outside and inside the panel, and a DC voltage of 200 V was applied. In this case, a voltage is applied to the molten salt and the glass panel via the molten salt. After 10 minutes, the polarity of the electrode was switched and a DC voltage was applied. After 10 minutes, the sample was taken out of the molten salt, gradually cooled to room temperature, washed, and the stress strain was measured. As a result, as shown in Table 5, it was found that a thick stress-strain layer can be obtained in a short time.

[0100]

[Table 5]

(Example 12) A glass having the composition shown in Table 5 was kept at 380 ° C with NaNO ₃ : KNO ₃ (weight ratio) =
It was immersed in 2: 3 molten salt. After immersion for 4 hours, it was taken out of the molten salt, gradually cooled to room temperature, and then washed. The glass was immersed in K ₂ S ₂ O ₇ kept at 250 ° C. for 10 minutes,
A dealkalization treatment was performed. After that, wash and again at 250 ° C
To remove the surface hydronium ions. A sample subjected to this treatment and a sample subjected to chemical strengthening only
It was immersed in pure water maintained at ° C. for 2 days, and the weight loss per unit surface area was measured. As a result, as shown in Table 6,
Since the chemical durability of the glass surface was increased, it was found that alkali elution from the panel surface could be suppressed, and improvement in browning resistance could be expected.

[0102]

[Table 6]

[0103]

According to the present invention, it is possible to obtain a glass composition for a cathode ray tube and a glass panel for a cathode ray tube having the glass composition necessary for realizing a thinner and lighter body and the properties of the glass. Accordingly, it is possible to reduce the thickness and weight of the glass for a cathode ray tube and the glass panel for a cathode ray tube. Further, according to the cathode ray tube and the method of manufacturing the same of the present invention, a cathode ray tube having sufficient strength and realizing a light weight can be obtained. In particular, according to the present invention, a glass panel for a flat cathode ray tube, which is reduced in thickness and weight, can be obtained.

[Brief description of the drawings]

FIG. 1 is a schematic diagram for explaining a chemical strengthening method according to one embodiment of the present invention.

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 4G059 HB03 HB13 HB14 4G062 AA03 BB01 CC01 CC10 DA05 DA06 DB02 DB03 DB04 DC01 DC02 DC03 DC04 DD01 DD02 DD03 DD04 DE01 DE02 DE03 DE04 DF01 EA03 EA04 EB02 EB03 EC01 EC03 EC03 ED03 EC04 ED04 EE01 EE02 EE03 EE04 EF03 EF04 EG01 EG02 EG03 EG04 FA01 FB02 FB03 FB04 FC02 FC03 FE01 FE02 FE03 FE04 FF01 FF02 FG01 FG02 FG03 H01 GE04 F01G01 F04G01 F04 HH05 HH07 HH08 HH09 HH10 HH11 HH12 HH13 HH15 HH17 HH20 JJ01 JJ03 JJ04 JJ05 JJ07 JJ10 KK01 KK03 KK05 KK07 KK10 MM25 NN14 NN33 NN35 NN40 5C012 AA02 BB01 BC01 5C032A

Claims (10)

[Claims] Claims: 1. A chemically strengthened glass having a Young's modulus of 9
Glass for a cathode ray tube, which is 0 GPa or more. 2. SiO ₂ , Al ₂ O ₃ , Li ₂ O, Na
It was obtained by chemically strengthening a base glass containing ₂ O, SrO, TiO ₂ , ZrO ₂ , and CeO ₂ and containing one or more oxides selected from the group consisting of MgO and CaO. The glass for a cathode ray tube according to claim 1, characterized in that: 3. SiO ₂ , Al ₂ O ₃ , Li ₂ O, Na
_{In addition} to containing ₂ O, SrO, TiO ₂ , ZrO ₂ , and CeO _{2, it} also contains one or more oxides selected from the group consisting of MgO and CaO, and Li ₂ O, SrO,
In the mole percent content of _{ZrO 2, Li 2 O 5~20%} , SrO 3~15%, for a cathode-ray tube matrix glass, wherein the ZrO ₂ 0.1 to 5%, it is. 4. SiO ₂ , Al ₂ O ₃ , Na ₂ O, Ti
The content of O ₂ , MgO and CaO is mol%, SiO ₂ 40 to 70%, Al ₂ O ₃ 0.1 to 15%, Na ₂ O 0.1 to 10%, MgO 0 to 15%, CaO 0 -15%, TiO ₂ 0.1-15%, and S
iO ₂ + Al ₂ O ₃ + Li ₂ O + Na ₂ O + SrO + TiO ₂
+ Cathode-ray tube matrix glass of claim 3, the total amount of _{ZrO 2 + MgO + CaO + CeO} 2 is characterized in that 85 mol% or more. 5. A glass for a cathode ray tube obtained by chemically strengthening the base glass for a cathode ray tube according to claim 3 or 4. 6. A cathode ray tube preform glass according to claim 3 or 4, wherein the base glass is heated to 350 to 550 ° C.
Alternatively, a method for producing glass for a cathode ray tube, wherein the glass is subjected to ion exchange in a treatment bath containing K ions to chemically strengthen it. 7. A glass panel for a cathode ray tube comprising the glass for a cathode ray tube according to claim 1. 8. A method for manufacturing a glass panel for a cathode ray tube, the step of processing the base glass for a cathode ray tube according to claim 3 or 4 into a panel shape, and the step of reducing the temperature of the glass processed in the step to 350 to 550 ° C. Ion-exchanging with a heated treatment bath containing Na ions and / or K ions to chemically strengthen the glass panel. 9. A cathode ray tube comprising the glass panel for a cathode ray tube according to claim 7. 10. A method of manufacturing a cathode ray tube, comprising a step of heating and integrating a glass panel for a cathode ray tube according to claim 7 and a funnel by frit sealing.