JP5762515B2 - Glass composition and glass article using the same - Google Patents

Description

  The present invention relates to a glass composition and a lighting glass article using the same. Specifically, the present invention relates to a glass composition suitable for a fluorescent lamp glass as a glass article and an illumination glass article using the same.

  As a glass for lighting such as a fluorescent lamp, a soda-lime-based glass composition containing 10 to 20% by mass of sodium oxide has been used. Mercury is sealed in the tube of the fluorescent lamp. From the glass for illumination which consists of a soda-lime-type glass composition, sodium may elute with progress of time.

  The phenomenon that the end portion of the fluorescent lamp is blackened and the life thereof is shortened occurs when the eluted sodium is combined with the above-described mercury and adheres to the inside of the fluorescent lamp. For this reason, it has been proposed to reduce the sodium content in the soda-lime glass composition.

For example, in the “lamp glass composition” disclosed in JP-A-11-224649, the total of Na ₂ O, K ₂ O and Li ₂ O is 13% or less.

In addition, in “Glass composition suitable for use of fluorescent lamp” disclosed in JP-A-11-509514 (WO97 / 43223), sodium is limited to a small amount (Na ₂ O <0.1 by weight%). doing.

  Further, the “lighting glass composition” disclosed in JP-A-2003-073142 does not substantially contain sodium.

In a glass composition for a fluorescent lamp, it is not preferable to cause solarization that lowers the transmittance of the glass by irradiation with ultraviolet rays. Some of the publications that mention solarization in glass compositions for fluorescent lamps are described below.
-JP 06-092677 A-JP 2001-243914 A-JP 2002-137935 A-JP 2003-171141 A

In general, soda-lime-based glass compositions inevitably contain iron due to industrial raw materials. Iron oxide contained in the glass acts as a colorant and exists in the form of Fe ²⁺ and Fe ³⁺ . Fe ²⁺ has an absorption peak near a wavelength of 1100 nm, and Fe ³⁺ has an absorption near a wavelength of 400 nm.

In a glass composition for a fluorescent lamp, transmittance is an important characteristic. Therefore, not only the content of iron oxide contained in the glass but also the ratio of Fe ²⁺ to Fe ³⁺ is important for the transmittance.

Some of the publications relating to glass compositions for lighting are described below.
JP-A 09-012332 JP-A 10-152340 JP-A 2000-290038 JP-A 2000-315477 JP-A 2005-314169

In the glass composition disclosed in Japanese Patent Application Laid-Open No. 11-224649, the inclusion of Sb ₂ O ₃ and CeO ₂ is allowed, and BaO is essential. There is no description about SO ₃ .
In the glass composition disclosed in Japanese Patent Application Laid-Open No. 11-509514, not only sodium is restricted but also CeO ₂ is allowed to be contained, and BaO is essential.
The glass composition disclosed in Japanese Patent Application Laid-Open No. 2003-073142 substantially does not contain sodium, allows the inclusion of Sb ₂ O ₃ and CeO ₂ , and contains BaO as an essential component. There is no description about SO ₃ .

In the glass composition disclosed in Japanese Patent Application Laid-Open No. 06-092677, Sb ₂ O ₃ is an essential component, CeO ₂ is allowed to be contained, and BaO is essential. There is no description about SO ₃ .
JP-A-2001-243914 Patent glass composition disclosed in JP, the CeO ₂ as an essential component, allows the content of Sb ₂ O _3, containing essential and BaO.
JP-A-2002-137935 Patent glass composition disclosed in JP, the CeO ₂ as an essential component, allows the content of Sb ₂ O _3, containing essential and BaO.
The glass composition disclosed in Japanese Patent Application Laid-Open No. 2003-171141 contains Sb ₂ O ₃ as an essential component and contains 0.5% by mass or more of Li ₂ O.

In the glass composition disclosed in Japanese Patent Application Laid-Open No. 09-012332, there is no description about Fe, and the inclusion of Sb ₂ O ₃ or CeO ₂ is allowed.
In the glass composition disclosed in Japanese Patent Application Laid-Open No. 10-152340, there is no description regarding SO ₃ or so-called iron ratio (for example, FeO / total iron oxide), the inclusion of Sb ₂ O ₃ is allowed, and BaO is essential. To do.
In the glass composition disclosed in Japanese Patent Application Laid-Open No. 2000-290038, there is no description regarding SO ₃ or a so-called iron ratio (for example, FeO / total iron oxide), and the inclusion of P ₂ O ₅ is allowed.
JP-A-glass composition disclosed in 2000-315477 JP, and Sb ₂ O ₃ as essential components, allowing the inclusion of P ₂ O _5, containing essential and BaO.
In the glass composition disclosed in Japanese Patent Application Laid-Open No. 2005-314169, there is no description regarding SO ₃ or a so-called iron ratio (for example, FeO / total iron oxide), and the inclusion of Sb ₂ O ₃ or CeO ₂ is allowed. Optionally contained.

Japanese Patent Laid-Open No. 11-224649 Japanese Patent Publication No. 11-509514 (International Publication No. 97/43223) JP 2003-073142 A Japanese Patent Laid-Open No. 06-092677 JP 2001-243914 A JP 2002-137935 A JP 2003-171141 A JP 09-012332 A JP-A-10-152340 JP 2000-290038 A JP 2000-315477 A JP-A-2005-314169

  An object of the present invention is to provide a glass composition that can have an ultraviolet transmittance, a thermal expansion coefficient, a glass transition point, and a softening point, which is preferable as an illumination glass while suppressing the sodium content in the glass composition. To do. Furthermore, it aims at provision of the glass article using this glass composition.

The present invention is a glass composition comprising SiO ₂ , Na ₂ O, K ₂ O, CaO and SO ₃ as essential components, particularly characterized by the content of Na ₂ O and K ₂ O, SO ₃ is 0.05% or more and 0.5% or less, and the total iron oxide converted to Fe ₂ O ₃ is 0.05% by mass or more and 0.35% by mass or less, and contains substantially no antimony oxide. It is the glass composition characterized.

That is, the present invention is expressed in mass%,
SiO ₂ 65% or more, 75% or less,
Al ₂ O ₃ 0.5 % or more, less than 1 %,
B ₂ O ₃ 0% or more, 5% or less,
Na ₂ O 7 % or more , 9 % or less ,
K ₂ O 6 % or more, less than 10 %,
Li ₂ O 0.05 % or more, less than 0.35 %,
Na ₂ O + K ₂ O + Li ₂ O 13.05 % or more, 17.5 % or less,
MgO more than 4 %, 5 % or less,
CaO more than 6 %, 10 % or less,
BaO 0% or more, less than 4%,
SrO 0 %,
ZnO 0 %,
MgO + CaO + SrO + BaO + ZnO more than 10 %, less than 15 % ,
T iO ₂ 0% or more and less than 0.05%,
ZrO ₂ 0% or more, less than 0.5 %,
CeO ₂ 0% or more, 0.5% or less,
SO ₃ 0.05% or more, 0.5% or less, and total iron oxide converted to Fe ₂ O ₃ 0.05% or more, 0.35% or less,
Comprising
It is a glass composition characterized by not containing antimony oxide substantially.

  The present invention suppresses the sodium content in the glass composition. When a fluorescent lamp is constructed using this glass composition, the elution of sodium is suppressed, which is effective in preventing blackening of the fluorescent lamp.

Further, the glass composition of the present invention is preferable as a glass for illumination because solarization is suppressed and it has a low ultraviolet ray transmittance.
Furthermore, this invention is a glass composition which has a thermal expansion coefficient, a glass transition point, and a softening point preferable as glass for illumination, and is excellent in a moldability.

It is a cross-sectional schematic diagram of the surface illumination device 1. It is a cross-sectional schematic diagram of the surface illumination device 2. 3 is a partially enlarged perspective view of the surface illumination device 3. FIG.

[Glass composition]
Below, each component in a glass composition is demonstrated. In addition, each content rate is a mass% display, and the ratio of a component is also a mass ratio.

(SiO ₂ )
SiO ₂ is a main component that forms a glass skeleton. If the content of SiO ₂ is less than 65%, the durability of the glass decreases. If it exceeds 75%, it becomes difficult to melt the glass, and the softening point of the glass becomes too high. The lower limit of the content of SiO ₂ is 65% or more, preferably 67% or more, and more preferably 68% or more. The upper limit of the content of SiO ₂ is 75% or less, preferably 73% or less, and more preferably 72% or less. The range of SiO ₂ is selected from any combination of these upper and lower limits.

(Al ₂ O ₃ )
Al ₂ O ₃ is an optional component that improves the durability of the glass, but if the Al ₂ O ₃ content is 5% or more, melting of the glass becomes difficult and the softening point of the glass becomes too high. The lower limit of the content of Al ₂ O ₃ is 0% or more, preferably more than 0%, more preferably 0.1% or more, and further preferably 0.5% or more. The upper limit of the content of Al ₂ O ₃ is less than 5%, preferably less than 2%, more preferably 1.5% or less, and most preferably less than 1%. The range of Al ₂ O ₃ is selected from any combination of these upper and lower limits.

(B ₂ O ₃ )
B ₂ O ₃ is an optional component used for improving the durability of the glass or as a melting aid. If B ₂ O ₃ exceeds 5%, inconvenience at the time of molding due to volatilization of B ₂ O ₃ occurs, so 5% is made the upper limit. Further, B ₂ O ₃ may erode the brick and shorten the life of the kiln, so it is desirable not to contain B ₂ O ₃ substantially.

(Na ₂ O)
Na ₂ O is used as a glass melting accelerator. When Na ₂ O is 3% or less, the melting promotion effect is poor. When Na ₂ O is 12% or more, the durability of the glass is lowered, and sodium elution, which is a problem particularly in glass for fluorescent lamps, is increased. The lower limit of the Na ₂ O content is more than 3%, preferably 4% or more, more preferably 6% or more, and even more preferably 7% or more. The upper limit of the Na ₂ O content is less than 12%, preferably 9% or less. The range of Na ₂ O is selected from any combination of these upper and lower limits.

(K ₂ O)
K ₂ O is an essential component used as a glass melting accelerator in the present invention, like Na ₂ O. If K ₂ O is less than 2%, the melting promotion effect is poor. Since K ₂ O is more expensive than Na ₂ O, it is not preferable to exceed 15%. The lower limit of the content of K ₂ O is 2% or more, preferably 4% or more, and more preferably 6% or more. The upper limit of the content of K ₂ O is 15% or less, preferably less than 10%, more preferably 9% or less, and still more preferably 8% or less. The range of K ₂ O is selected from any combination of these upper and lower limits.

(Li ₂ O)
Li ₂ O is not an essential component, but is used as a glass melting accelerator in the same manner as Na ₂ O and K ₂ O. Further, it is an effective component for adjusting the thermal expansion coefficient and low temperature viscosity, and it is preferable to contain even a trace amount. On the other hand, since Li ₂ O is more expensive than Na ₂ O, 5% or more is not preferable. The lower limit of the content of Li ₂ O is 0% or more, preferably more than 0%, more preferably 0.05% or more, and most preferably 0.1% or more. The upper limit of the content rate of Li ₂ O is less than 5%, preferably 3% or less, more preferably 1.5% or less, further preferably 1% or less, still more preferably less than 1%, 0.5 % Is even more preferred, and less than 0.35% is most preferred. The range of Li ₂ O is selected from any combination of these upper and lower limits.

(Na ₂ O + K ₂ O + Li ₂ O)
If the total of (Na ₂ O + K ₂ O + Li ₂ O) is less than 6%, the effect of promoting melting is poor, and if it exceeds 20%, the durability of the glass is lowered. The total lower limit of (Na ₂ O + K ₂ O + Li ₂ O) is 6% or more, and preferably 10% or more. The upper limit of the total of (Na ₂ O + K ₂ O + Li ₂ O) is 20% or less, preferably less than 19.5%, more preferably 17.5% or less. The range of (Na ₂ O + K ₂ O + Li ₂ O) is selected from any combination of these upper limit value and lower limit value.

(Na ₂ O / K ₂ O)
In the present invention, the ratio of Na ₂ O to K ₂ O (Na ₂ O / K ₂ O) is important. A large ratio of Na ₂ O and K ₂ O is not preferable because sodium elution increases. When the ratio of Na ₂ O and K ₂ O is small, expensive K ₂ O increases, which is not preferable.
In the present invention, the lower limit of Na ₂ O / K ₂ O is preferably more than 0.2, more preferably 0.6 or more, and even more preferably 0.9 or more. The upper limit of Na ₂ O / K ₂ O is preferably less than 3, more preferably 1.5 or less, and even more preferably 1.1 or less. The range of Na ₂ O / K ₂ O is selected from any combination of these upper and lower limits.

(MgO)
MgO is not an essential component, but is used to improve the durability of the glass and adjust the devitrification temperature and viscosity during molding. When MgO exceeds 10%, the devitrification temperature rises. The lower limit of the content of MgO is 0% or more, preferably more than 0%, more preferably 2% or more, and further preferably more than 4%. The upper limit of the content of MgO is 10% or less, preferably 6% or less, and more preferably 5% or less. The range of MgO is selected from any combination of these upper and lower limits.

(CaO)
Like MgO, CaO is an essential component used to improve the durability of glass and adjust the devitrification temperature and viscosity during molding. When CaO is 5% or less, the meltability deteriorates. On the other hand, if it exceeds 15%, the devitrification temperature rises. The lower limit of the CaO content is more than 5%, preferably 5.5% or more, more preferably 6% or more, and further more preferably 6%. The upper limit of the CaO content is 15% or less, preferably 12% or less, more preferably 10% or less, and even more preferably 8% or less. The range of CaO is selected from any combination of these upper and lower limits.

(SrO)
Although SrO is not an essential component, it is used to adjust the devitrification temperature and viscosity at the time of forming the glass in the same manner as MgO and CaO. Although the content rate of SrO shall be 10% or less, when comprising SrO as much as possible and comprising a glass composition, the content rate is preferably less than 4% and more preferably less than 1%.
On the other hand, the present invention can be realized even if 4% or more of SrO is included. In that case, the lower limit of SrO is preferably 4% or more, more preferably more than 4%. The upper limit value of SrO is preferably 7% or less, and more preferably 6% or less. When SrO is contained in an amount of 4% or more, moldability is improved.

(BaO)
BaO is not an essential component, but is used to adjust the devitrification temperature and viscosity at the time of molding the glass in the same manner as MgO and CaO. When the content of BaO is large, the density of the glass increases, which is disadvantageous in terms of weight reduction when used as a glass article. Therefore, the upper limit of BaO is less than 4%, more preferably less than 1%. . The glass composition of the present invention can be established without substantially containing BaO.

(ZnO)
Although ZnO is not an essential component, it is used to adjust the devitrification temperature and viscosity at the time of molding the glass, similarly to MgO and CaO. ZnO tends to volatilize and the glass tends to be inhomogeneous. When glass is formed by the float process, the glass often volatilizes in the float bath and then agglomerates at a low temperature part. Aggregation of ZnO may cause glass surface defects, so the content is 10% or less, preferably 6% or less, more preferably 5% or less, but ZnO should not be substantially contained. Is preferred.

(MgO + CaO + SrO + BaO + ZnO)
When the total of (MgO + CaO + SrO + BaO + ZnO) is 5% or less, the durability of the glass is lowered. On the other hand, if it exceeds 19%, the devitrification temperature rises or the thermal expansion coefficient becomes too large. The lower limit of the content of (MgO + CaO + SrO + BaO + ZnO) is more than 5%, and preferably 10% or more. The upper limit of the content of (MgO + CaO + SrO + BaO + ZnO) is 19% or less, preferably 16% or less, and more preferably less than 15%. The range of (MgO + CaO + SrO + BaO + ZnO) is selected from any combination of these upper and lower limits.

(SrO + BaO + ZnO)
If the amount of (SrO + BaO + ZnO) increases, the expansion coefficient becomes too large. Therefore, it is not preferable that the total exceeds 10%. The lower limit of the content rate of (SrO + BaO + ZnO) is 0% or more. The upper limit of the content of (SrO + BaO + ZnO) is 10% or less, preferably 8% or less, more preferably 6% or less, and even more preferably 5% or less. The range of (SrO + BaO + ZnO) is selected from any combination of these upper and lower limits.

(TiO ₂ )
TiO ₂ is not an essential component, but can be added as long as the object of the present invention is not impaired. If the amount of TiO ₂ is excessive, the glass tends to be yellowish. Therefore, the upper limit of the content of TiO ₂ is 0.5% or less, preferably less than 0.1%, and less than 0.05%. Is more preferable. On the other hand, the lower limit of the content of TiO ₂ is 0% or more. The range of TiO ₂ is selected from any combination of these upper and lower limits.

(ZrO ₂ )
ZrO ₂ is not an essential component, but is an effective component for improving the durability of the glass and adjusting the devitrification temperature during molding. If it exceeds 2.5%, devitrification tends to occur. Further, ZrO ₂ is expensive as a raw material, and is desirably less than 0.5%. The lower limit of the content of ZrO ₂ is 0% or more. The upper limit of the content of ZrO ₂ is 2.5% or less, preferably less than 0.5%, and more preferably less than 0.2%. The range of ZrO ₂ is selected from any combination of these upper and lower limits.

(CeO ₂ )
CeO ₂ exhibits an action of absorbing ultraviolet rays in glass, and is an effective component for suppressing ultraviolet transmittance. The glass composition of the present invention may contain 0.5% or less. However, since solarization occurs due to ultraviolet irradiation and the visible light transmittance of the glass is lowered, it is more preferable not to contain it substantially.

(SO ₃ )
SO ₃ is a component that promotes clarification of glass. If it is less than 0.05%, the clarification effect is insufficient by a normal melting method, and the desirable range is 0.1% or more. On the other hand, if it exceeds 0.5%, SO ₂ produced by the decomposition thereof remains in the glass as bubbles or bubbles are likely to be generated by reboil. The lower limit of the content of SO ₃ is 0.05% or more, preferably 0.1% or more. The upper limit of the content of SO ₃ is 0.5% or less. The range of SO ₃ is selected from any combination of these upper and lower limits.

(Total iron oxide (T-Fe ₂ O ₃ ))
The content of iron oxide, all iron contained and terms of Fe ₂ O _3, as the total iron oxide _{(T-Fe 2 O 3)} , is 0.05% to 0.35%. If the total iron oxide is less than 0.05%, Fe ³⁺ having an absorption in the ultraviolet region becomes too small, and the ultraviolet transmittance becomes high. On the other hand, when the total iron oxide is more than 0.35%, with Fe ³⁺ having an absorption in the visible short wavelength region, for Fe ²⁺ having absorption in the visible long wavelength side is too large, the visible light transmittance Will be lower. The lower limit of the total iron oxide content is 0.05% or more, preferably 0.1% or more. The upper limit value of the total iron oxide content is 0.35% or less, preferably 0.25% or less. The range of total iron oxide is selected from any combination of these upper and lower limits.

(Iron ratio)
The iron ratio, which is the ratio of FeO converted to Fe ₂ O ₃ with respect to total iron oxide, is sometimes referred to as FeO ratio. If the FeO ratio is less than 10%, the amount of Fe ³⁺ having an absorption in the visible short wavelength region is excessive, so that the visible light transmittance is lowered and the yellow color of the glass becomes too strong. When the FeO ratio exceeds 40%, the amount of Fe ²⁺ having absorption on the visible long wavelength side is excessive, so that the visible light transmittance is lowered and the blue color of the glass becomes too strong. The lower limit of the iron ratio is preferably 10% or more, and more preferably 15% or more. The upper limit of the iron ratio is preferably 40% or less, and more preferably 35% or less. The range of the iron ratio is selected from any combination of these upper and lower limits.

(Antimony oxide)
Antimony oxide is a component that promotes clarification of the glass. For example, when glass containing antimony oxide is formed by a float process, the glass is colored by the reducing atmosphere in the float bath. It is also a component that can be a burden on the environment. Therefore, in the present invention, antimony oxide is not substantially contained.

  In the present invention, “substantially does not contain” means that the corresponding component is not actively added, and means that contamination as an unavoidable impurity is allowed. Even when the corresponding component is mixed as an inevitable impurity, the content is preferably less than 0.1%.

The glass composition of the present invention may contain components other than the above components and unavoidable impurities as long as the effects of the present invention are not impaired. However, P ₂ O ₅ is a component that easily volatilizes, and may cause problems during molding similar to B ₂ O ₃ and ZnO. Therefore, in the present invention, P ₂ O ₅ is substantially not included. Preferably not.

For the glass composition of the present invention, a particularly preferred first composition is
SiO ₂ 65% or more, 75% or less,
Al ₂ O ₃ 0.5% or more, less than 2%,
B ₂ O ₃ 0% or more, 5% or less,
Na ₂ O 6% or more, 9% or less,
K ₂ O 4% or more, less than 10%,
Li ₂ O 0% or more, less than 1%,
Na ₂ O + K ₂ O + Li ₂ O 10% or more, 17.5% or less,
MgO 0% or more, 5% or less,
CaO over 6%, 12% or less,
BaO 0% or more, less than 4%,
SrO 0% or more, less than 4%,
ZnO 0% or more, 5% or less,
MgO + CaO + SrO + BaO + ZnO 10% or more, less than 15%,
SrO + BaO + ZnO 0% or more, 5% or less,
TiO ₂ 0% or more, 0.5% or less,
ZrO ₂ 0% or more, 2.5% or less,
CeO ₂ 0% or more, 0.5% or less,
SO ₃ 0.05% or more, 0.5% or less, and total iron oxide converted to Fe ₂ O ₃ 0.05% or more, 0.35% or less,
It is.

The In the first composition, with a less Na ₂ O content than the current soda lime glass, as compared with the current soda lime glass, it is realized with a thermal expansion coefficient close, lower softening point.

In the first composition, Al ₂ O ₃ is 0.5% or more and less than 1%, Na ₂ O is 7% or more and 9% or less, K ₂ O is 6% or more and less than 10%, Li ₂ O is 0.05% or more, less than 0.35%, MgO more than 4%, 5% or less, SrO 0% or more, less than 1%, TiO ₂ 0% or more, less than 0.05%, ZrO ₂ 0% As mentioned above, it is more preferable that it is less than 0.5%.

For the glass composition of the present invention, a particularly preferred second composition is:
SiO ₂ 67% or more, 73% or less,
Al ₂ O ₃ more than 0%, less than 2%,
B ₂ O ₃ 0% or more, 5% or less,
Na ₂ O 4% or more, 9% or less,
K ₂ O 2% or more, 9% or less,
Li ₂ O over 0%, 3% or less,
Na ₂ O + K ₂ O + Li ₂ O 10% or more, less than 19.5%,
MgO over 0%, 6% or less,
CaO over 5%, 10% or less,
BaO 0% or more, less than 1%,
SrO 4% or more, 7% or less,
ZnO 0% or more, 6% or less,
MgO + CaO + SrO + BaO + ZnO 10% or more, 19% or less,
SrO + BaO + ZnO 0% or more, 10% or less,
TiO ₂ 0% or more, 0.5% or less,
ZrO ₂ 0% or more, 2.5% or less,
CeO ₂ 0% or more, 0.5% or less,
SO ₃ 0.05% or more, 0.5% or less, and total iron oxide converted to Fe ₂ O ₃ 0.05% or more, 0.35% or less,
It is.

In the second composition, with a Na ₂ O content lower than that of the current soda lime glass, a near thermal expansion coefficient and a lower softening point are realized as compared with the current soda lime glass, and molding is performed. It is a glass composition excellent in properties.

In the second composition, Al ₂ O ₃ is 0.1% or more and less than 2%, Na ₂ O is 6% or more and 9% or less, Li ₂ O is 0.1% or more and 1.5% or less, MgO is 2% to 6%, CaO is 5.5% to 10%, TiO ₂ is 0% to less than 0.05%, and ZrO ₂ is 0% to less than 0.5%. Is more preferable. Further, SiO ₂ is 68% or more, 72% or less, Al ₂ O ₃ is 0.5% or more and less than 2%, Na ₂ O is more than 7%, 9% or less, K ₂ O is more than 4%, 8% Hereinafter, Li ₂ O is 0.1% to 1%, MgO is 2% to 5%, CaO is 5.5% to 8%, and SrO is 4% to 6%. Is more preferable.

[Characteristics of glass composition]
(Transmittance)
As the glass for illumination, it is desirable that the visible light transmittance is high. The generation of visible light in a fluorescent lamp utilizes light emission when the generated ultraviolet light is irradiated on a phosphor on the inner surface of the fluorescent lamp. Thus, ultraviolet rays are generated inside the fluorescent lamp. Since it is necessary to reduce leakage of ultraviolet rays, the transmittance of wavelengths in the ultraviolet region must be kept low. Ultraviolet light includes light having a wavelength such as 254 nm or 313 nm. In the case of glass, light with a wavelength of 254 nm is hardly transmitted, and thus need not be considered. The transmission of light having a wavelength of 313 nm needs to be controlled, and can be controlled mainly by the contents of Fe ₂ O ₃ and titanium oxide in the total iron oxide. The transmittance of light having a wavelength of 313 nm (glass thickness: 0.7 mm) is preferably 60% or less, and more preferably 45% or less.

(Coefficient of thermal expansion)
When used as lighting glass, the thermal expansion coefficient of the glass needs to be balanced with the thermal expansion coefficient of the sealing glass used. This sealing glass is used for sealing electrodes inserted into the interior in the case of internal electrode type illumination, and is used for laminating sheet glass to form a glass container in the case of a surface illumination device.

In a frequently used sealing glass, its thermal expansion coefficient is usually adjusted to be balanced with 89 × 10 ⁻⁷ / ° C., which is a representative value of the thermal expansion coefficient of a soda-lime-based glass composition. Therefore, it is desired that the thermal expansion coefficient of the lighting glass is not so far from this value. Specifically, it is preferably in the range of (89 ± 5) × 10 ⁻⁷ / ° C., more preferably in the range of (89 ± 4) × 10 ⁻⁷ / ° C., and (89 ± 2) × 10 More desirably, it is in the range of ^-7 / ° C.

(Softening point, glass transition point)
When the lighting glass container is tubular, it is directly molded into a tubular shape from molten glass, or once formed into a tubular shape, it is heated to a temperature at which it is softened again and reshaped into a U-shape. . In the case of a surface illumination device, in order to form a glass container for illumination, the plate-like glass may be heated to a temperature at which it is softened again and used for press molding or the like. Therefore, it is preferable that the softening point is low so that the work can be easily performed during molding by heating and reheating. It is desirable that the softening point is not so high compared to that of current soda-lime glass compositions. Specifically, the softening point is preferably 790 ° C. or less, which is about 50 ° C. higher than the softening point of the soda-lime glass composition, and more preferably 750 ° C. or less, which is about 10 ° C. higher. Furthermore, 740 ° C. or lower, which is lower than the softening point of the current soda-lime glass composition, is most desirable.

  Further, since the measurement of the softening point is often difficult, this may be substituted by the glass transition point. In terms of glass transition point, it is preferably less than 630 ° C., more preferably less than 600 ° C., and most preferably 565 ° C. or less.

  Here, (softening point-glass transition point) is a parameter serving as an index of a cooling rate after re-forming by reheating. The larger the (softening point-glass transition point), the faster the glass cooling rate during cooling after re-forming by reheating. Therefore, the productivity of the remolding process is improved. The cooling rate is given as a numerical value obtained by dividing (softening point-glass transition point) by the time required for cooling from the softening point to the glass transition point.

The (softening point-glass transition point) of the glass composition of the present invention has a value equal to or greater than the (softening point-glass transition point) of the current soda-lime glass composition. In the present invention, (softening point-glass transition point) in Examples 22, 24 to 26 and Reference Examples 1 , 3 , 4 , 8 to 21 , 23 , and 27 to 42 described later are values exceeding 184 ° C. . On the other hand, in the comparative example, the value is 184 ° C. or lower. For this reason, in the said Example and reference example , it is possible to enlarge a cooling rate compared with a comparative example. That is, for the glass composition of the present invention, the cooling rate at the time of reshaping can be made equal to or greater than that in the past.

(Glass forming method)
The glass composition of the present invention can be formed into tubular glass or sheet glass. In particular, as a method for forming into a sheet glass, a float method capable of being manufactured at a low cost and in a large amount is desirable, and the glass composition of the present invention is applicable to the float method. Of course, it is also possible to form a tube that is generally used as a fluorescent lamp. The specific molding method may be in accordance with a known method.

(Use of glass composition)
The glass composition of the present invention, for example, as described above, using a glass article formed into a plate shape by a float method or the like, or a glass article formed into a container shape, and a lighting device such as a fluorescent lamp according to a known method (example: , Surface illumination devices, tubular fluorescent lamps, and the like).

Hereinafter, the present invention will be described in detail with reference to examples, reference examples, and comparative examples.
Raw material batches (hereinafter sometimes referred to as batches) were prepared so that the glass compositions shown in Tables 1 to 4 were obtained. The raw materials used were those used for normal glass production.

(In Tables 1 to 4, R ₂ O represents Na ₂ O + K ₂ O + Li ₂ O, RO-1 represents MgO + CaO + SrO + BaO + ZnO, and RO-2 represents SrO + BaO + ZnO.)

  The blended batch was melted and clarified in a platinum crucible. First, the crucible was held in an electric furnace set at 1500 ° C. for 4 hours to melt the batch. Thereafter, the glass melt was poured onto an iron plate to obtain a plate-like glass body. This glass body was held in another electric furnace set at 650 ° C. for 1 hour, and then cooled to room temperature at a cooling rate of 2 ° C. per minute. This slowly cooled glass body was used as a sample glass.

(Measurement of transmittance)
About some of the obtained sample glasses, the transmittance | permeability was measured with the spectrophotometer (the Hitachi make, U4100) using A light source. The thickness of the glass substrate was 0.7 mm. As a measure of the ultraviolet transmittance, the transmittance of light having a wavelength of 313 nm was measured. Further, the visible light transmittance was measured according to the method for measuring the visible light transmittance of JIS R 3106.

(Composition analysis)
The composition of the obtained sample glass was quantitatively analyzed using fluorescent X-ray analysis and chemical analysis.

(Measurement of thermal expansion coefficient)
The thermal expansion coefficient of some of the obtained sample glasses was measured with a differential thermal dilatometer (manufactured by Rigaku, TAS-100). The size of the sample was 5 mm in diameter and 17 mm in length. The sample was measured in the range from room temperature to the yield temperature at a heating rate of 5 ° C./min, and the thermal expansion coefficient in the range of 50 ° C. to 300 ° C. was calculated.

(Measurement of softening point and glass transition point)
For some of the obtained sample glasses, the penetration indenter was lowered to a flat sample at a constant load, and the viscosity was calculated from the penetration speed of the indenter to obtain the softening point.
Moreover, the glass transition point was calculated | required from the inflection point in the thermal expansion curve calculated | required by the measurement of the above-mentioned thermal expansion coefficient.

(Measurement of devitrification temperature)
The sample glass pulverized to a particle size of 1.0 to 2.8 mm is placed in a platinum boat and kept in an electric furnace with a temperature gradient for 2 hours. From the maximum temperature at which the crystal appears, devitrification occurs. The temperature was determined.

(Measurement of molding temperature)
The viscosity of the glass was determined by a normal platinum ball pulling method, and the temperature (forming temperature) at which the viscosity of the glass was 10000 dPas (10000 poise) was determined.

  The above measurement results are also shown in Tables 1 to 4.

In Examples 22, 24 to 26 and Reference Examples 1 to 21, 23, and 27, the Na ₂ O content is 4.37% to 10.8%, and the Na ₂ O / K ₂ O is 0.3 to 2.6. The thermal expansion coefficient is (74.7-95.6) × 10 ⁻⁷ / ° C., and the transition point is 532 ° C. to 622 ° C. In other words, it has a Na ₂ O content that is less than that of current soda-lime glass and has properties that are relatively close to it, and has suitable characteristics as a glass composition for lighting.

In Examples 22, 24 to 26 and Reference Examples 21 , 23, and 27, the Na ₂ O content was 7.94% to 8.08%, and Na ₂ O / K ₂ O was 0.9 to 1.1. The thermal expansion coefficient is (88.1-92.4) × 10 ⁻⁷ / ° C., the transition point is 536 ° C. to 551 ° C., and the softening point is 724 ° C. to 739 ° C. In other words, with a much lower Na ₂ O content than the current soda lime glass, a very close thermal expansion coefficient and a lower softening point are realized as compared with the current soda lime glass. For this reason, it has the characteristic especially suitable as a glass composition for illumination.

Comparative Example 1 is a general soda-lime glass composition for sheet glass. It contains a large amount of Na ₂ O as 13.1% and is outside the glass composition range of the present invention. Moreover, almost no K ₂ O is contained and Na ₂ O / K ₂ O is 15.1.

  Comparative Example 2 is a soda-lime-based glass composition containing a large amount of iron for a general plate glass.

Comparative Example 3 is a glass composition disclosed in Example 8 of JP-A No. 05-314169, and does not contain SO ₃ but contains Sb ₂ O ₃ as a fining agent.

Comparative Example 4 is a glass composition shown in Example 7 of JP-A-11-224649, and is a glass composition having a small content of alkali metal oxide and a small content of CaO. Furthermore, as a clarifier, it does not contain SO ₃ but contains CeO ₂ or Sb ₂ O ₃ .

Comparative Example 5 is a glass composition containing Sb ₂ O ₃ as a fining agent and having a very small FeO ratio.

Comparative Examples 3 and 4 are examples that do not contain SO ₃ . Comparative Examples 3 and 4 both contain Sb ₂ O ₃ as a fining agent, and Comparative Example 4 further contains CeO ₂ . When the glass compositions of Comparative Examples 3 and 4 are molded by the float process, they are colored brown by the reducing atmosphere in the float bath. Furthermore, in the comparative example 4, it will be colored yellow by irradiation of an ultraviolet-ray.

In Comparative Example 2, since the contained iron content is large, the visible light transmittance is 89.3%, which is lower than those in Example 22 and Reference Examples 20 , 21, and 23.

Each batch was prepared so as to have the glass composition shown in Tables 5 and 6. Reference Examples 28 to 42 have a glass composition containing about 4.5% SrO. Comparative Example 6 is a general soda-lime glass composition for plate glass. It contains a large amount of Na ₂ O as 13.12% and is outside the glass composition range of the present invention. Moreover, almost no K ₂ O is contained and Na ₂ O / K ₂ O is 11.82.

(In Tables 5 and 6, R ₂ O represents Na ₂ O + K ₂ O + Li ₂ O, RO-1 represents MgO + CaO + SrO + BaO + ZnO, and RO-2 represents SrO + BaO + ZnO.)

Reference Examples 28 to 42 have a Na ₂ O content of 5.20% to 8.03%, a Na ₂ O / K ₂ O of 0.68 to 2.24, and a thermal expansion coefficient of (83.7 to 94.2) × 10 ⁻⁷ / ° C., transition point is 526 ° C. to 561 ° C. In other words, it has a Na ₂ O content lower than that of the current soda-lime glass and has properties that are relatively close to it, and has suitable characteristics as a glass composition for a tube. In Reference Example 35, the transmittance at a wavelength of 313 nm is 36.7% and the transmittance for visible light is 91.5%. In Reference Example 41, the transmittance at a wavelength of 313 nm is 27.8%, and the visible light is transmitted. The transmittance was 91.3%.

  Below, the glass composition by this invention is shape | molded by the float method at plate shape, and the example which comprised the surface illumination apparatus using the glass substrate is demonstrated.

(Application 1)
Application Example 1 is a surface illumination device in which a casing is formed using the glass substrate described above. In FIG. 1, the cross-sectional schematic diagram of the surface illumination apparatus by the application example 1 is shown. The surface illumination device 1 is configured by first joining a flat plate-like first glass substrate 11 and a second glass substrate 12 having a U-shaped cross-section by a glass frit 13 to form a container, the interior of which is a space. S. A pair of discharge electrodes 14 and 14 are provided at both ends inside the container. In addition, phosphors 15 and 15 are applied to the surfaces facing the space S in the first glass substrate 11 and the second glass substrate 12. Further, mercury and an inert gas such as argon are sealed in the space S inside the container.

  When the discharge electrodes 14 and 14 are discharged by applying a voltage, ultraviolet rays are generated. The ultraviolet rays enter the phosphors 15 and 15 to emit visible light and function as an illumination device.

  In the glass substrate according to the present invention, since the sodium content is suppressed, the surface illumination device 1 configured using the glass substrate has a feature that a blackening phenomenon due to sodium elution hardly occurs.

(Application example 2)
The application example 2 uses the above-mentioned two glass substrates, and provides a large number of partition walls between them to form a large number of cells to form a surface illumination device. In FIG. 2, the cross-sectional schematic diagram of the surface illumination apparatus by the application example 2 is shown. The surface illumination device 2 holds the two glass substrates 21 and 22 at a constant interval, and provides a large number of partition walls 23... The cell S is configured. Further, phosphors 25 and 25 are applied to the surfaces of the glass substrates 21 and 22 facing the cell S. Further, the cell S is filled with mercury and an inert gas such as argon. The surface illumination device 2 is caused to discharge by applying a voltage to an electrode (not shown) to function as a light source.

(Application 3)
Application Example 3 is a surface illumination device having a structure in which a large number of cells are provided in the same manner as Application Example 2. In application example 2, a large number of partition walls are provided to separate a large number of cells. However, in application example 3, one glass substrate is press-molded to form a large number of ridges so that the joining portion becomes the partition wall. It is a thing.

  FIG. 3 shows a partially enlarged perspective view of the surface illumination device 3 according to the application example 3. The surface illumination device 3 is composed of a number of cells S by first joining a flat plate-like first glass substrate 31 and a second glass substrate 32 having a shape in which a large number of ridges are arranged in parallel by press molding. is there. At this time, the bonding portion 33 of the second glass substrate 32 bonded to the first glass substrate 31 is a partition wall. Further, phosphors 35 and 35 are applied to the surfaces of the glass substrates 31 and 32 facing the cell S. Further, the cell S is filled with mercury and an inert gas such as argon. The surface illumination device 3 is discharged by applying a voltage to an electrode (not shown) to function as a light source.

  The glass article obtained by molding the glass composition of the present invention is useful as a lighting glass such as a phosphor.

Claims (21)

Display in mass%,
SiO ₂ 65% or more, 75% or less,
Al ₂ O ₃ 0.5% or more, less than 1%,
B ₂ O ₃ 0% or more, 5% or less,
Na ₂ O 7% or more, 9% or less,
K ₂ O 6% or more, less than 10%,
Li ₂ O 0.05% or more, less than 0.35%,
Na ₂ O + K ₂ O + Li ₂ O 13.05% or more, 17.5% or less,
MgO more than 4%, 5% or less,
CaO over 6%, 10% or less,
BaO 0% or more, less than 4%,
SrO 0%,
ZnO 0%,
MgO + CaO + SrO + BaO + ZnO more than 10%, less than 15%,
TiO ₂ 0% or more, less than 0.05%,
ZrO ₂ 0% or more, less than 0.5%,
CeO ₂ 0% or more, 0.5% or less,
SO ₃ 0.05% or more, 0.5% or less, and total iron oxide converted to Fe ₂ O ₃ 0.05% or more, 0.35% or less,
Comprising
A glass composition characterized by being substantially free of antimony oxide. The glass composition according to claim 1,
The glass composition in which the total iron oxide is 0.1% or more and 0.25% or less. The glass composition according to claim 1,
Wherein of the total iron oxide, the ratio of FeO which in terms of Fe ₂ O ₃ is the 10% to 40% of the total iron oxide, the glass composition. In the glass composition according to claim 3,
The ratio of FeO which in terms of Fe ₂ O ₃ of the total iron oxide, wherein from 15% to 35% of the total iron oxide, the glass composition. The glass composition according to claim 1,
The glass composition wherein the ZrO ₂ is 0% or more and less than 0.2%. The glass composition according to claim 1,
The glass composition which the said glass composition does not contain BaO substantially. The glass composition according to claim 1,
It said glass composition contains substantially no CeO _2, the glass composition. The glass composition according to claim 1,
It said glass composition contains substantially no B ₂ O _3, the glass composition. The glass composition according to claim 1,
A glass composition having a transmittance of light having a wavelength of 313 nm of 60% or less when the glass composition has a thickness of 0.7 mm. The glass composition according to claim 9,
A glass composition having a transmittance of light having a wavelength of 313 nm of 45% or less when the glass composition has a thickness of 0.7 mm. The glass composition according to claim 1,
A glass composition having a thermal expansion coefficient in the range of (89 ± 5) × 10 ⁻⁷ / ° C. The glass composition according to claim 11,
A glass composition having a thermal expansion coefficient in the range of (89 ± 2) × 10 ⁻⁷ / ° C. The glass composition according to claim 1,
A glass composition having a softening point of 790 ° C. or lower. The glass composition according to claim 13,
The glass composition whose said softening point is 750 degrees C or less. The glass composition according to claim 14,
The glass composition whose said softening point is 740 degrees C or less.   A glass article comprising the glass composition according to claim 1 and formed into a plate shape.   The glass article according to claim 16, wherein the forming is performed by a float process.   It is a glass article of Claim 16, Comprising: The glass article used for the glass container for illumination.   The glass article for illumination according to claim 18, wherein the illumination is a fluorescent lamp.   The glass article which consists of a glass composition of Claim 1, and is used for the glass container for illumination.   The glass article for illumination according to claim 20, wherein the illumination is a fluorescent lamp.

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