JP2005267988A - Panel for cathode ray tube, and manufacturing method of the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a panel for cathode ray tube and manufacturing method of the same capable of recycling waste glass generated when manufacturing glass substrates for plasma display. <P>SOLUTION: The panel for cathode ray tube is manufactured by using the wasted glass generated when manufacturing the glass substrates for plasma display as a part of glass raw material, and it contains SO<SB>3</SB>by 0.06 to 0.3 wt.%. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

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

The envelope of the cathode ray tube includes a panel portion on which an image is projected, a tubular neck portion on which an electron gun is mounted, and a funnel-shaped funnel portion connecting the panel portion and the neck portion. The electron beam emitted from the electron gun causes the phosphor provided on the inner surface of the panel unit to emit light and display an image on the panel unit. At this time, braking X-rays are generated in the tube, and if this leaks outside the tube through the envelope, the human body is adversely affected. Therefore, this type of envelope is required to have a high X-ray absorption capability. For example, in the case of the panel, an X-ray absorption coefficient in order to 28cm ^-1 or more at 0.6 Å, glass large amount is contained SrO and BaO are used. (See Patent Document 1)
JP 2001-328835 A

  By the way, recently, the production volume of plasma displays has increased because it is thinner and easier to enlarge than the cathode ray tube, and the production volume tends to increase more and more in the future.

  Usually, glass substrates used in plasma displays are molded into a plate-like body by pulling the molten glass supplied to the molded body with a roller, etc., and after cutting off both ends of the plate-like body in contact with the roller, the appearance quality Etc., and those having no defects such as bubbles and blisters are used. Therefore, when manufacturing a glass substrate, waste glass, such as a glass substrate which has the both ends of a plate-shaped body, and a defect generate | occur | produces.

  When the production amount of the glass substrate is small, the generation amount of waste glass can be reduced. Therefore, these glasses can be pulverized and recycled as a glass raw material for the glass substrate for plasma display.

  However, if the production volume of the glass substrate increases, the amount of waste glass generated increases more than the expansion of the production volume, so that it cannot be completely digested only by using it as a glass raw material for the glass substrate for plasma display. Problems arise.

  From the viewpoint of preventing environmental pollution, waste reduction and resource reuse are strongly demanded, and it is not desirable to dispose of waste glass generated when manufacturing glass substrates as industrial waste. How to recycle unnecessary glass generated when manufacturing a glass substrate has become an important issue.

  The objective of this invention is providing the panel for cathode ray tubes which can recycle the waste glass generate | occur | produced when manufacturing the glass substrate for plasma displays, and its manufacturing method.

As a result of repeating various experiments, the present inventors produce a glass substrate for plasma display by adjusting the SO ₃ content in the glass and the temperature distribution in the melting furnace in the panel used for the cathode ray tube. The present invention finds and proposes that waste glass generated at the time can be recycled as a glass raw material for a cathode ray tube panel.

That is, the cathode ray tube panel of the present invention is manufactured using waste glass generated when manufacturing a glass substrate for plasma display as a part of glass raw material, and SO ₃ is 0.06-0. It consists of glass containing 3 mass%.

Further, the method of manufacturing a cathode ray tube panel of the present invention, the glass used waste glass generated when producing a glass substrate for a plasmapheresis display, the SO ₃ so that the glass containing 0.06 to 0.3 wt% After the raw materials are mixed, the glass raw material is introduced into a glass melting furnace having the lowest temperature on the glass raw material inlet side and the temperature distribution adjusted so that the temperature near the center of the melting furnace is the highest. The obtained molten glass lump is molded by a molding die.

Since the cathode ray tube panel of the present invention adjusts the SO ₃ content and the temperature distribution of the melting furnace, waste glass generated when manufacturing a glass substrate for plasma display should be used as part of the glass raw material. The glass having such a configuration has few bubbles and no spots, and reboil hardly occurs. Therefore, it is suitable as a cathode ray tube panel.

As a method for recycling the above waste glass, a method in which the waste glass is pulverized and mixed with other glass raw materials for the cathode ray tube panel and melted can be considered. This is because the glass composition of the glass substrate for plasma display does not contain PbO that causes browning but contains many components that increase the X-ray absorption coefficient such as SrO, BaO, and ZrO ₂ .

However, a glass substrate for plasma display, because it is produced by a float process, a SO ₃ as a fining component in the glass is contained 0.05 to 0.8 wt%, inadvertently those containing SO ₃ glass When mixed with the raw material and melted, a rapid vitrification reaction of the glass raw material occurs and becomes a glass melt while vigorously foaming. And the foam generated when the glass raw material melts spreads in the length direction of the melting furnace and forms a foam layer on the surface of the glass melt. Since this foam layer becomes a heat insulating layer, heat does not reach the bottom of the melting furnace, and the temperature of the bottom of the melting furnace decreases. As a result, bubbles and blisters remain in the product, and a decrease in vacuum strength and airtightness is expected when a cathode ray tube is produced. In addition, since the heat is not sufficiently transferred to the molten glass, the glass after molding contains a large amount of dissolved gas, and when the stud pins are welded to the panel glass after molding, the glass is heated or sealed with funnel glass. When heated, the gas solubility is lowered, and there is a problem that foaming (reboil) occurs in the heated portion.

According to the knowledge of the present inventor, when SO ₃ mixed from the waste glass increases, the vitrification reaction of the glass raw material occurs abruptly to form a bubble layer on the surface of the glass melt. Strictly limits the SO ₃ in the glass to 0.3% or less, thereby suppressing the rapid vitrification reaction of the glass raw material and preventing the formation of a bubble layer on the surface of the glass melt. . However, if the content of SO ₃ is less than 0.06%, the amount of waste glass used is small, and recycling is not promoted.

  In addition, as usage-amount of said waste glass, it is preferable to mix and use with a glass raw material in the range of 1-50 mass% (preferably 1-40 mass%). When the amount of waste glass used is more than 50%, it is difficult to correct the characteristics required for the cathode ray tube panel, and the characteristics required for the cathode ray tube panel, such as a low thermal expansion coefficient and difficulty in matching with the funnel. It becomes impossible to satisfy. On the other hand, if the amount of waste glass used decreases, recycling will not proceed.

Further, in the glass raw material containing SO ₃ , the vitrification reaction rapidly occurs as the melting temperature increases. Therefore, in order to more effectively suppress the formation of a foam layer on the surface of the glass melt, in the glass melting furnace, the temperature near the glass raw material inlet is lowered, the glass raw material is slowly melted, and the length of the kiln is It is desirable to melt by gradually raising the temperature relative to the direction.

The cathode ray tube panel of the present invention is made of glass having a thermal expansion coefficient of 95 to 105 × 10 ⁻⁷ / ° C. (preferably 98 to 103 × 10 ⁻⁷ / ° C.) in order to match the thermal expansion coefficient of the funnel. It is preferable.

Further, it is preferably made of glass having an X-ray absorption coefficient of 28 cm ⁻¹ or more at a wavelength of 0.6 mm. This is because if the X-ray absorption coefficient is smaller than 28 cm ⁻¹ , X-rays that adversely affect the human body may leak out of the tube. Note that the X-ray absorption coefficient of the glass to 28cm ^-1 or more, SrO, BaO, may be contained a ZrO ₂ or the like.

Further, the preferred glass composition range of the cathode ray tube panel of the present invention is substantially free of PbO, and is expressed by mass percentage, SiO ₂ 50 to 70%, Al ₂ O ₃ 1 to 3%, MgO 0 to 3%. , CaO 0 to 3%, SrO 7 to 10%, BaO 7 to 10%, ZnO 0 to 2%, Na ₂ O 5 to 10%, K ₂ O 5 to 10%, ZrO ₂ 0 to 3%, TiO _{2 0~3%, CeO 2 0~3%,} Sb 2 O 3 0~2%, a SO ₃ 0.06 to 0.3%.

  The reason for limiting the glass composition as described above in the present invention is as follows.

  PbO is a component that enhances the X-ray absorption ability of glass. However, when PbO is contained, coloring called browning is caused by electron beam and X-ray irradiation, so that introduction into a substantial glass should be avoided. In addition, substantial introduction into glass means that PbO is 0.1% or less.

SiO ₂ is a glass network former. When the content increases, the viscosity of the glass becomes high and melting becomes difficult, or the coefficient of thermal expansion becomes too small, and the consistency with the funnel glass tends to be difficult. On the other hand, when the content is reduced, the viscosity of the glass becomes low and molding becomes difficult, or the coefficient of thermal expansion becomes too large, and the consistency with the funnel glass tends to be difficult. If the content of SiO ₂ is 50 to 70%, it becomes easy to obtain a glass having a coefficient of thermal expansion that matches the funnel glass without deteriorating the meltability and formability of the glass. A preferred range is 53-67%.

Al ₂ O _{3 is} also a component that becomes a glass network former. When the content increases, the viscosity of the glass becomes high and melting becomes difficult, or the coefficient of thermal expansion becomes too small, and the consistency with the funnel glass tends to be difficult. On the other hand, when the content is reduced, the viscosity of the glass becomes low and molding becomes difficult, or the coefficient of thermal expansion becomes too large, and the consistency with the funnel glass tends to be difficult. If the content of Al ₂ O ₃ is 1 to 3%, it becomes easy to obtain a glass having a thermal expansion coefficient that matches the funnel glass without deteriorating the meltability and formability of the glass. A preferable range is 1.2 to 2.8%.

  MgO and CaO are components that facilitate melting of the glass and adjust the thermal expansion coefficient and viscosity. When each content increases, the glass tends to be devitrified and difficult to be molded. If the content of MgO and CaO is 0 to 3%, respectively, it is easy to obtain a glass that is not easily devitrified. A preferable range is 0 to 2.5% or less, respectively.

  SrO and BaO are components that facilitate melting of the glass, adjust the thermal expansion coefficient and viscosity, and increase the X-ray absorption ability. When each content increases, the glass tends to be devitrified and difficult to be molded. On the other hand, when the content decreases, sufficient X-ray absorption ability tends to be difficult to obtain. If the content of SrO and BaO is 7 to 10%, respectively, it becomes easy to obtain a glass having a sufficient X-ray absorption coefficient without devitrification. Preferable ranges are 7.2 to 9.8%, respectively.

  ZnO is a component that facilitates melting of the glass, adjusts the thermal expansion coefficient and viscosity, and further increases the X-ray absorption ability. When the content increases, the glass tends to be devitrified and difficult to mold. If the content of ZnO is 0 to 2%, it becomes easy to obtain a glass having a sufficient X-ray absorption coefficient without devitrifying the glass. The preferred ranges are each 0-1.8%.

Na ₂ O and K ₂ O are components that adjust the thermal expansion coefficient and viscosity. If each content increases, the thermal expansion coefficient becomes too large, making it difficult to achieve consistency with the funnel glass, and the viscosity becomes too low to make molding difficult. In addition, the electrical insulation tends to decrease. On the other hand, when the content is reduced, the thermal expansion coefficient is lowered, and it tends to be difficult to match the thermal expansion coefficient of the funnel glass. If the content of Na ₂ O and K ₂ O is 5 to 10%, respectively, it becomes easy to obtain a glass having a thermal expansion coefficient that matches the funnel glass without degrading the formability and the electrical insulation. Preferable ranges are 6 to 9%, respectively.

ZrO ₂ is a component that adjusts the thermal expansion coefficient and viscosity, and further increases the X-ray absorption ability. When the content increases, the glass tends to be devitrified and difficult to mold. If the content of ZrO ₂ is 0 to 3%, the glass having a sufficient X-ray absorption coefficient is easily obtained without devitrification. A preferable range is 0 to 2.5%.

TiO ₂ is a component that suppresses ultraviolet coloring of glass. Even if TiO ₂ is contained in an amount of more than 3%, the effect cannot be remarkably obtained, and the raw material cost increases. A preferable range is 0 to 2%.

CeO ₂ is a component that suppresses X-ray coloring of glass. Even if CeO ₂ is contained in an amount of more than 3%, the effect cannot be obtained remarkably, and the raw material cost increases. A preferable range is 0 to 2%.

Sb ₂ O ₃ is a component that acts as a fining agent. Even if Sb ₂ O ₃ is contained in an amount of more than 2%, the effect cannot be obtained remarkably, and the raw material cost increases. A preferable range is 0 to 1%.

SO ₃ is a component mixed from waste glass generated when manufacturing a glass substrate for plasma display, impurities of glass raw material, and fuel such as heavy oil used when melting glass, and waste glass is not used as a raw material. Is mixed in a range of 0.05% or less. When the content of SO ₃ is more than 0.3%, the vitrification reaction of the glass raw material occurs abruptly, forming a foam layer on the surface of the glass melt, or welding a stud pin to the molded panel glass Reheating at the time of sealing with the funnel glass is not preferable because reboiling occurs in the heating part. On the other hand, if the SO ₃ content is less than 0.06%, the amount of waste glass that can be recycled is small, which is not preferable. A preferable range is 0.06 to 0.28%, and a more preferable range is 0.07 to 0.27%.

In addition to the above components, it is possible to add other components as long as the properties of the glass are not impaired. For example, P ₂ O ₅ is added up to 0.5% as a component for suppressing devitrification. Also good. Further, CoO, NiO, and Fe ₂ O ₃ may be added up to 1% in total as colorants.

  Next, a method for manufacturing a cathode ray tube panel will be described.

  First, waste glass generated when producing a glass substrate for plasma display is pulverized, and the obtained waste glass pieces and glass raw materials are prepared and mixed so as to be in the above glass composition range. Subsequently, the prepared glass raw material is put into a continuous melting furnace, the glass raw material is heated and melted by a burner flame in which fuel such as heavy oil is burned, defoamed, and the molten glass is supplied to a molding apparatus and press-molded. Slowly cool.

  The temperature distribution in the melting furnace is preferably adjusted as follows. First, in order to suppress the rapid vitrification reaction of the glass raw material and prevent the formation of a foam layer, the temperature on the glass raw material inlet side is made the lowest in the melting furnace. Subsequently, in order to cause defoaming near the center in the length direction of the melting furnace, the temperature is gradually increased from the glass raw material inlet to near the center of the melting furnace so that the temperature near the center of the melting furnace becomes the highest. The temperature is gradually lowered from the vicinity of the center of the melting furnace to the vicinity of the molten glass lead-out end.

  By doing in this way, even if the waste glass is used as a glass raw material, it is possible to suppress the rapid vitrification reaction of the glass raw material and prevent the formation of a foam layer on the surface of the glass melt. A panel for a cathode ray tube can be obtained in which heat is sufficiently transmitted to the bottom of the melting kiln, there are few bubbles and blisters, and no reboiling occurs.

  Hereinafter, the cathode ray tube panel of the present invention will be described in detail based on examples.

  Tables 1 and 2 show examples (sample Nos. 1 to 8) and comparative examples (sample No. 9) of the present invention.

  Each sample in the table was prepared as follows.

First, by mass percentage, SiO ₂ 54.3%, Al ₂ O ₃ 7%, MgO 2%, CaO 2%, SrO 9%, BaO 9%, Na ₂ O 5%, K ₂ O 7%, ZrO ₂ Prepare a waste glass by pulverizing a glass substrate for plasma display having a composition of 4.5% and SO ₃ 0.2%, and use the waste glass and the glass raw material so that the glass composition shown in the table is obtained. Mix. Next, the prepared raw material batch is put into a refractory crucible having a thermocouple attached to the bottom. Subsequently, the raw material batch was melted in a melting furnace heated only from the top of the crucible, and the temperature at the bottom of the crucible was measured. Sample No. 1, no. 2 and no. About No. 5-9, it fuse | melted on 1500 degreeC and the conditions for 4 hours, and sample No.5. 3 and no. No. 4 was melted at 1200 ° C. for 2 hours and then melted at 1500 ° C. for 2 hours. Sample No. 2 and no. The SO ₃ of ₄ was adjusted by adding mirabilite (Na ₂ SO ₄ ) in addition to waste glass.

  The thickness of the foam layer, the temperature at the bottom of the crucible, the number of remaining bubbles, the evaluation of the reboilability, the thermal expansion coefficient, and the X-ray absorption coefficient of each sample thus obtained were measured and shown in the table.

As is apparent from the table, the sample No. In Nos. 1 to 8, the thickness of the foam layer was as thin as 3.6 mm or less, the temperature at the bottom of the crucible was 1255 ° C. or more, and the remaining number of foams was 40/100 g or less. Also, no foaming was observed in the evaluation of reboilability. Furthermore, the thermal expansion coefficient was a thermal expansion coefficient that matched with the funnel at 100 to 100.5 × 10 ⁻⁷ / ° C., and the X-ray absorption coefficient was as high as 29 cm ⁻¹ .

On the other hand, sample No. which is a comparative example. In No. 9, the thickness of the foam layer was as thick as 5.2 mm, the temperature at the bottom of the crucible was as low as 1225 ° C., and the remaining number of foams was as large as 100/100 g. Further, foaming occurred in the evaluation of the reboilability. Furthermore, the thermal expansion coefficient was as small as 93.0 × 10 ⁻⁷ / ° C., and it was difficult to match the thermal expansion coefficient of the funnel.

  In addition, about the thickness of a foam layer, it annealed and cut | disconnected the center part of the crucible longitudinally, and measured the thickness of the foam layer in the glass surface.

  The remaining number of bubbles is obtained by converting glass below 3 cm from the foam layer with a diamond cutter and measuring the number of bubbles, and then converting to 100 g of glass.

  For the evaluation of reboilability, glass 3 cm below the foam layer was cut out with a diamond cutter, the collected glass piece was mirror-polished, washed with alcohol, then heated with a Kinoshita blue burner for 10 seconds to check for foaming did. In addition, the thing in which foaming did not arise was set as (circle), and the thing in which foaming produced was set as x.

  Regarding the thermal expansion coefficient, a cylindrical sample having a diameter of 5.0 mm and a length of 20 mm was prepared, and the average thermal expansion coefficient at 30 to 300 ° C. was measured with a dilatometer.

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

  Next, based on the above results, sample No. The melting temperature in the vicinity of the glass raw material inlet is about 1300 ° C., the melting temperature in the vicinity of the center of the melting furnace is about 1550 ° C., and the melting temperature in the vicinity of the molten glass outlet end is about 1300 ° C. A panel for a cathode ray tube was manufactured by melting in a continuous melting furnace having a temperature distribution adjusted to 1400 ° C. and press molding. In the glass melting furnace, a foam layer on the surface of the glass melt was thin, and a panel with few bubbles and blisters was obtained. Furthermore, even when the stud pin was welded or sealed with the funnel, no reboiling occurred in the seal portion.

  In addition, in the Example, the glass substrate for plasma displays which consists of the said glass composition was used for the waste glass, but the waste glass used for this invention is not limited to the glass substrate which consists of the said glass composition. Needless to say, a glass substrate made of another glass composition may be crushed and used.

Claims (6)

Waste glass generated when manufacturing a glass substrate for plasma display is manufactured using a part of glass raw material, and made of glass containing 0.03 to 0.3% by mass of SO _3. Characteristic cathode ray tube panel.   2. The cathode ray tube panel according to claim 1, wherein the glass raw material contains 1 to 50 mass% of waste glass. 3. The cathode ray tube panel according to claim 1, wherein the panel is made of glass having a thermal expansion coefficient of 95 to 105 × 10 ⁻⁷ / ° C. The cathode ray tube panel according to any one of claims 1 to 3, wherein the cathode ray tube panel is made of glass having an absorption coefficient for X-rays of 0.6 cm or more at 28 cm ^-1 or more. Substantially free of PbO and in mass percentage, SiO ₂ 50-70%, Al ₂ O ₃ 1-3%, MgO 0-3%, CaO 0-3%, SrO 7-10%, BaO 7- 10%, ZnO 0 to 2%, Na ₂ O 5 to 10%, K ₂ O 5 to 10%, ZrO ₂ 0 to 3%, TiO ₂ 0 to 3%, CeO ₂ 0 to 3%, Sb ₂ O ₃ a cathode ray tube panel as claimed in any one of claims 1 to 4, characterized in that it consists of 0-2%, glass containing SO ₃ 0.06 to 0.3%. Using the waste glass generated when manufacturing the glass substrate for plasma display, the glass raw material is prepared so as to be a glass containing 0.06 to 0.3% by mass of SO ₃ , and the temperature on the glass raw material inlet side is The glass raw material is charged into a glass melting furnace whose temperature distribution is adjusted to be the lowest and the temperature in the vicinity of the center of the melting furnace is the highest, and after melting, the resulting molten glass lump is molded with a mold. A method for producing a cathode ray tube panel, comprising: