JP5445190B2 - High transmission glass plate and manufacturing method thereof - Google Patents

Description

  The present invention relates to a highly transmissive glass plate and a method for producing the same.

  Since a solar cell can generate power by light in the visible light region and near infrared region, a visible light transmittance and a solar transmittance (hereinafter referred to as Te) are used for a glass plate for a solar cell (cover glass, glass substrate for a thin film solar cell). There is a demand for glass plates that are sufficiently high. Therefore, as the glass plate for solar cells, a highly transmissive glass plate (so-called white plate glass) in which the content of coloring components (particularly iron) is extremely reduced to increase the visible light transmittance and the solar radiation transmittance is used (Patent Document). 1).

  However, even a highly transmissive glass plate includes iron inevitably mixed in production. Therefore, in the high transmission glass plate, the ratio of divalent iron having a peak of absorption in the vicinity of a wavelength of 1100 nm and absorption at a wavelength shorter than the wavelength of 800 nm out of the total iron contained in the high transmission glass plate. It is important to reduce as much as possible.

By the way, when a highly transmissive glass plate is used as a glass substrate for a thin film solar cell, a transparent conductive film (hereinafter also referred to as a TCO film) containing SnO ₂ as a main component is formed. There are a float glass method, a fusion method, a down draw method, etc. in the manufacturing method of glass, and a TCO film | membrane is often formed in the middle of the manufacturing process of a highly permeable glass plate. Then, the defective or broken pieces generated from the manufacturing process of the high-permeability glass plate with the TCO film, or the high-permeability glass plate with the TCO recovered from the used thin film solar cell was crushed into cullet (glass waste). Later, it is reused as part of the glass raw material.

However, since the cullet of the highly transparent glass plate with a TCO film contains a large amount of SnO ₂ from the TCO film, the glass plate obtained by melting and molding the glass raw material containing the cullet must also contain tin. become. And when tin is contained in a glass plate, the ratio (what is called Redox) of the bivalent iron of the total iron contained in a glass plate will increase, and visible light transmittance and especially solar radiation transmittance will fall. End up. This increase in Redox proceeds mainly during the glass cooling process.
Therefore, the cullet of the highly transmissive glass plate with a TCO film cannot be reused as a glass material for the highly permeable glass plate, but is reused as a glass material for colored glass.

In addition, as a glass composition for high transmissive glass plates, the total iron converted to Fe ₂ O ₃ is 0.04% or less and the total antimony converted to Sb ₂ O ₃ is 0 in terms of mass percentage based on oxide. It is known that the mass ratio of divalent iron converted to Fe ₂ O ₃ in the total iron converted to Fe ₂ O ₃ is 0.05 to 0.5% and is 5 to 20% ( Patent Document 2).
However, the glass composition is for a template glass produced by a manufacturing method called a roll-out method, and is not used for a float method, a fusion method, a downdraw method, or the like. Therefore, in the roll-out method, a TCO film is not formed during the glass manufacturing process. Therefore, tin is not mixed when reused as cullet, and the above-described problems caused by tin do not occur.

JP-A-4-228450 JP 2007-238398 A

  The present invention relates to a method for producing a high transmission glass plate in which the cullet of a high transmission glass plate with a TCO film can be reused as a raw material of the high transmission glass plate; and visible light transmittance despite containing iron and tin And a highly transmissive glass plate having particularly high solar transmittance.

The method for producing a highly transmissive glass plate of the present invention comprises melting a glass raw material containing a cullet of a highly transmissive glass plate having a transparent conductive film containing SnO ₂ formed on its surface in a mass percentage display of more than 0% and 80% or less. A method of manufacturing a highly transmissive glass plate,
The highly transmissive glass plate after molding contains 0.0001 to 0.3% of all antimony converted to Sb ₂ O ₃ in terms of oxide-based mass percentage,
Highly transmissive glass plate after molding
JIS R 3106 (1998) prescribed visible light transmittance (by A light source) is 91.5% or more in terms of 4 mm thickness conversion,
The solar transmittance according to JIS R 3106 (1998) is 90.9% or more in terms of 4 mm thickness conversion value.

The high transmission glass plate after molding is a mass percentage display based on oxide,
SiO _2: 65~80%,
Al ₂ O _3: 0~5%,
MgO: 0 to 12%,
CaO: 0 to 15%,
Na ₂ O: 5~20%,
K ₂ O: 0~10%,
_{Na 2 O + K 2 O:} 5~20%,
Total sulfur converted to SO ₃ : 0.05 to 0.5%,
Total iron converted to Fe ₂ O ₃ : 0 to 0.04%,
Total antimony converted to Sb ₂ O ₃ : 0.0001 to 0.3%,
Total tin converted to SnO ₂ : 0.005 to 0.2% included,
Divalent weight ratio of iron in terms of _Fe 2 _{O 3} in the total iron in terms of Fe ₂ O ₃ is preferably 30% or less.

The high-transmission glass plate of the present invention is an oxide-based mass percentage display,
SiO _2: 65~80%,
Al ₂ O _3: 0~5%,
MgO: 0 to 12%,
CaO: 0 to 15%,
Na ₂ O: 5~20%,
K ₂ O: 0~10%,
_{Na 2 O + K 2 O:} 5~20%,
Total sulfur converted to SO ₃ : 0.05 to 0.5%,
Total iron converted to Fe ₂ O ₃ : 0 to 0.04%,
Total antimony converted to Sb ₂ O ₃ : 0.0001 to 0.3%,
Total tin converted to SnO ₂ : 0.005 to 0.2% included,
Mass percentage of divalent iron in terms of _Fe 2 _{O 3} in the total iron in terms of Fe ₂ O ₃ is not more than 30%,
JIS R 3106 (1998) prescribed visible light transmittance (by A light source) is 91.5% or more in terms of 4 mm thickness conversion,
The solar transmittance according to JIS R 3106 (1998) is 90.9% or more in terms of 4 mm thickness conversion value.

According to the method for producing a highly permeable glass plate of the present invention, the cullet of the highly permeable glass plate with a TCO film can be reused as a raw material for the highly permeable glass plate.
The high-transmission glass plate of the present invention has high visible light transmittance and particularly solar radiation transmittance, despite containing iron and tin.

It is a graph which shows the relationship between Redox and Te in an Example.

The highly transmissive glass plate of the present invention is produced, for example, through the following steps (i) to (vi) in order.
(I) Various glass matrix composition raw materials, cullet, fining agent, and the like are mixed to prepare a glass raw material so as to achieve a target composition.
(Ii) A glass raw material is melted to obtain molten glass.
(Iii) After the molten glass is clarified, it is formed into a glass plate having a predetermined thickness by a float method, a fusion method, a downdraw method or the like.
(Iv) If necessary, a TCO film is formed on the surface of the glass plate.
(V) Cool the glass plate.
(Vi) A glass plate is cut into a predetermined size.

Step (i):
As a glass mother composition raw material, what is used as a raw material of normal soda-lime silica glass, such as silica sand, is mentioned.

In the present invention, a cullet of a highly transmissive glass plate with a TCO film is used as a part or all of the cullet.
The ratio of the cullet of the highly transmissive glass plate with a TCO film is expressed as a percentage by mass and is more than 0% and 80% or less of the glass raw material (100%). If the cullet ratio of the high-permeability glass plate with a TCO film is 80% or less, the ratio of tin oxide mixed from the TCO film can be kept low, and cullet of other glasses having different glass compositions are mixed as impurities. Even in this case, the iron content mixed during the cullet recycling process can be kept low, and the glass having the desired composition can be adjusted. The proportion of cullet in the high-permeability glass plate with a TCO film is preferably 20 to 80% in terms of mass percentage, from the viewpoint of reducing raw material batch cost and improving clarity and obtaining glass with good foam quality. -70% is more preferable.

Examples of the fining agent include Sb ₂ O ₃ and SO ₃ .
In the present invention, Sb is added to the glass raw material so that the highly transparent glass plate after molding contains 0.0001 to 0.3% of all antimony converted to Sb ₂ O ₃ in terms of oxide-based mass percentage. _An antimony component is added in the form of oxides such as ₂ O ₃ , Sb ₂ O ₅ , NaSbO ₃ , halides such as SbCl ₃ , SbCl ₅ , SbF ₃ , and SbF ₅ . At this time, nitrate such as NaNO ₃ may be added simultaneously as an oxidizing agent. Antimony acts as an oxidant and fining agent, but if it is only for the purpose of obtaining a high transmittance as in the present invention, nitrate is not particularly required, so if you want to keep batch costs low. Rather, it is desirable not to add nitrate. When the content of total antimony in terms of sb ₂ O ₃ is 0.0001% or more, by weight percentage of divalent iron in terms of _Fe 2 _{O 3} in the total iron in terms of _Fe 2 _{O 3} 30% It is suppressed to the following. When molded by a float process, if the total content of antimony in terms of Sb ₂ O ₃ is 0.3% or less, clouding high transmittance glass sheet after forming is suppressed. The content of all antimony converted to Sb ₂ O ₃ is preferably 0.01 to 0.25%, more preferably 0.03 to 0.2% in terms of mass percentage based on oxide. When molding by the float process, it is desirable to make it 0.15% or less.

Step (ii):
The glass raw material is melted, for example, by continuously supplying the glass raw material to a melting furnace and heating it to about 1500 ° C. with heavy oil, gas, electricity or the like.

The thus highly transparent glass plate obtained in the mass percentage of divalent iron in terms of _Fe 2 _{O 3} in the total iron in terms of _Fe 2 _{O 3} (hereinafter referred to as Redox.) Is 30% or less As a result, the visible light transmittance defined by JIS R 3106 (1998) (according to the A light source) (hereinafter referred to as Tv) is 91.5% or more in terms of 4 mm thickness, and JIS R 3106 (1998) prescribed solar radiation transmittance is 90.9% or more in terms of 4 mm thickness conversion value.

The highly transmissive glass plate after molding is preferably made of soda lime silica glass having the following composition.
In mass percentage display based on oxide,
SiO _2: 65~80%,
Al ₂ O _3: 0~5%,
MgO: 0 to 12%,
CaO: 0 to 15%,
Na ₂ O: 5~20%,
K ₂ O: 0~10%,
_{Na 2 O + K 2 O:} 5~20%,
Total sulfur converted to SO ₃ : 0.05 to 0.5%,
Total iron converted to Fe ₂ O ₃ : 0 to 0.04%,
Total antimony converted to Sb ₂ O ₃ : 0.0001 to 0.3%,
Total tin converted to SnO ₂ : 0.005 to 0.2%,
including.

SiO ₂ is a main component of glass, and if the content is less than 65%, the stability of the glass is lowered. If the content of SiO ₂ exceeds 80%, the melting temperature of the glass rises and there is a possibility that it cannot be melted. The content of SiO ₂ is preferably 68 to 76%, more preferably 70 to 74% in terms of mass percentage based on oxide.

Al ₂ O ₃ is a component that improves weather resistance.
If the content of Al ₂ O ₃ is 0% or more and 0.1% or more, the weather resistance will be good, but if the content of Al ₂ O ₃ exceeds 5%, the solubility will deteriorate. The content of Al ₂ O ₃ is preferably from 0.3 to 3%, more preferably from 0.5 to 2.5% in terms of oxide based mass percentage.

MgO is a component that promotes melting of the glass raw material and adjusts viscosity, thermal expansion coefficient, and the like.
When the content of MgO exceeds 12%, the devitrification temperature increases. The content of MgO is preferably 1 to 10%, more preferably 2 to 8% in terms of mass percentage based on oxide.

CaO is a component that promotes melting of the glass raw material and adjusts viscosity, thermal expansion coefficient, and the like.
When the content of CaO exceeds 15%, the devitrification temperature increases. The content of CaO is preferably 2 to 12% and more preferably 4 to 10% in terms of mass percentage based on oxide.

Na ₂ O is an essential component that promotes melting of the glass raw material.
When the content of Na ₂ O exceeds 20%, the weather resistance and stability of the glass deteriorate. If it is less than 5%, melting of the glass becomes difficult. The content of Na ₂ O is preferably 8 to 16%, more preferably 10 to 15% in terms of oxide percentage.

K ₂ O is not essential, but is a component that promotes melting of the glass raw material and adjusts thermal expansion, viscosity, and the like.
When the content of K ₂ O exceeds 10%, the weather resistance and stability of the glass deteriorate. In addition, the batch cost increases. The content of K ₂ O is preferably 0 to 5% and more preferably 0 to 2% in terms of mass percentage based on oxide.

If the content of Na ₂ O + K ₂ O is less than 5%, the solubility is deteriorated. Moreover, when it exceeds 20%, the weather resistance and stability of glass will deteriorate. The content of Na ₂ O + K ₂ O is preferably 8 to 18%, more preferably 10 to 15% in terms of mass percentage based on oxide.

The highly transmissive glass plate of the present invention may contain SO ₃ as a fining agent. The content of total sulfur converted to SO ₃ is preferably 0.5% or less in terms of oxide based mass percentage. If the total sulfur content converted to SO ₃ exceeds 0.5%, reboyl is generated in the process of cooling the glass melt, and the foam quality may be deteriorated. If it is less than 0.05%, a sufficient clarification effect cannot be obtained. The content of total sulfur converted to SO ₃ is more preferably 0.1 to 0.4%, and further preferably 0.1 to 0.3% in terms of mass percentage based on oxide.

Fe ₂ O ₃ is a coloring component inevitably mixed in production.
If the total iron content converted to Fe ₂ O ₃ is 0.04% or less, a decrease in Tv can be suppressed. In particular, as a glass plate for a solar cell, the total iron content converted to Fe ₂ O ₃ is preferably 0.02% or less, more preferably 0.015% or less in terms of mass percentage on an oxide basis, and 01% or less is more preferable.

In the present specification, the total iron content is expressed as the amount of Fe ₂ O ₃ according to the standard analysis method, but not all iron present in the glass is present as trivalent iron. Usually, divalent iron is present in the glass. Divalent iron has an absorption peak near a wavelength of 1100 nm, absorption at a wavelength shorter than 800 nm, and trivalent iron has an absorption peak near a wavelength of 400 nm. An increase in divalent iron results in an increase in absorption in the near-infrared region around 1100 nm described above, and when this is expressed in Te, it means that Te decreases. Therefore, when focusing on Tv and Te, by suppressing the content of total iron converted to Fe ₂ O ₃ , the decrease in Tv is suppressed, and when focusing on Te, trivalent iron is more than divalent iron. More is preferable. Therefore, in terms of suppressing the decrease in Tv and Te, it is preferable to reduce the total iron amount and suppress Redox.

  Redox in the highly transmissive glass plate of the present invention is 30% or less. If Redox is 30% or less, Te can be kept low. Redox is preferably 20% or less, and more preferably 10% or less.

SnO ₂ is an impurity that is inevitably mixed in production by using a cullet with a TCO film as a part of the glass raw material.
In order to obtain a high transmittance, the content of all tin in glass converted to SnO ₂ needs to be 0.2% or less. However, in order to suppress it to less than 0.005%, it is necessary to suppress the usage rate of the cullet of the highly transmissive glass plate with a TCO film, and the raw material cost becomes high.

Sb ₂ O ₃ is a component that keeps Redox in the highly transmissive glass plate after molding low. In addition, since Redox of glass to which Sb ₂ O ₃ is added does not depend on the cooling condition of the glass, the increase in Redox can be suppressed even if the cooling rate becomes slow due to changes in the capacity and shape of the glass melting furnace. it can.
If the total antimony content converted to Sb ₂ O ₃ is 0.0001% or more, Redox can be suppressed to 30% or less. If the content of all antimony converted to Sb ₂ O ₃ exceeds 0.3%, the raw material cost will increase. In the case of float forming, if the content of all antimony converted to Sb ₂ O ₃ exceeds 0.3%, the highly transmissive glass plate after forming becomes cloudy. The content of all antimony converted to Sb ₂ O ₃ is preferably 0.01 to 0.25%, more preferably 0.03 to 0.2% in terms of mass percentage based on oxide. When molding by the float process, it is desirable to make it 0.15% or less.

It is preferable that the highly transmissive glass plate of the present invention does not substantially contain TiO ₂ , CoO, Cr ₂ O ₃ , V ₂ O ₅ , and MnO, which are coloring components. TiO _{2, CoO,} and _{Cr 2 O 3, V 2 O} 5, substantially free of MnO does _not include _{TiO 2, CoO, Cr 2 O} 3, V 2 O 5, the MnO completely, or, TiO ₂ , CoO, Cr ₂ O ₃ , V ₂ O ₅ , and MnO may be included as impurities inevitably mixed in production. If TiO ₂ , CoO, Cr ₂ O ₃ , V ₂ O ₅ and MnO are not substantially contained, Tv and Te can be kept low.

  Te (4 mm thickness conversion) of the highly transmissive glass plate of the present invention is 90.9% or more, and preferably 91.0% or more. Te is the solar radiation transmittance calculated by measuring the transmittance with a spectrophotometer according to JIS R 3106 (1998) (hereinafter simply referred to as JIS R 3106).

  Tv (4 mm thickness conversion) of the highly transmissive glass plate of the present invention is 91.5% or more, preferably 91.6% or more. Tv is the visible light transmittance calculated by measuring the transmittance with a spectrophotometer in accordance with JIS R 3106. As the coefficient, the standard light A and the value of the 2-degree visual field are used.

  The highly transmissive glass plate of the present invention is suitable as a glass plate for solar cells. When used as a glass plate for a solar cell, it may be used as a cover glass or a glass substrate for a thin film solar cell.

In the method for producing a highly transmissive glass plate of the present invention described above, a glass raw material containing a cullet of a highly transmissive glass plate having a TCO film formed on the surface in a mass percentage display of more than 0% and 80% or less, In the manufacturing method of the highly transmissive glass plate to be molded, the highly transmissive glass plate after molding contains 0.0001 to 0.3% of all antimony converted to Sb ₂ O ₃ in terms of oxide-based mass percentage, Since an antimony component is added to the glass raw material, Redox can be kept low. As a result, a highly transmissive glass plate having a sufficiently high Te can be obtained in spite of containing iron and tin. Thus, according to the manufacturing method of the highly permeable glass plate of this invention, the cullet of the highly permeable glass plate with a TCO film | membrane can be reused as a raw material of a highly permeable glass plate.

EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated concretely, this invention is not limited to these examples.
Examples 4 to 12 are examples, examples 2 and 3 are comparative examples, and example 1 is a reference example.

(Redox)
About the obtained glass plate, Redox was computed using the following Formula (1).
Redox (%) =-log (T _{1000 nm} /91.4)/(Fe ₂ O ₃ amount × t × 20.79) × 100 (1).
However,
T _{1000 nm} is the transmittance (%) at a wavelength of 1000 nm measured by a spectrophotometer (Perkin Elmer, Lambda 950),
t is the thickness (cm) of the glass plate;
The amount of Fe ₂ O ₃ is the total iron content (% = mass percentage) calculated by fluorescent X-ray measurement and converted to Fe ₂ O ₃ .

(Tv)
About the obtained glass plate, visible light transmittance | permeability (Tv) (those by A light source) prescribed | regulated to JISR3106 was calculated | required by 4 mm thickness conversion value.

(Te)
About the obtained glass plate, the solar radiation transmittance | permeability (Te) prescribed | regulated to JISR3106 was calculated | required by 4 mm thickness conversion value.

[Examples 1, 3-5, 7-21]
Melting condition A:
Various glass matrix composition raw materials such as silica sand, cullet of high transmission glass plate with TCO film, Sb ₂ O ₃ , oxidizing agent (NaNO ₃ ), refining agent (SO ₃ ) so as to have the composition shown in Table 1 and Table 2. ) Were mixed to prepare a glass raw material. The glass raw material was put in a crucible and heated in an electric furnace at 1500 ° C. for 3 hours to obtain molten glass. Molten glass was poured onto a carbon plate and cooled. Both surfaces were polished to obtain a glass plate having a thickness of 4 mm. About the glass plate, the transmittance | permeability was measured for every 1 nm using the spectrophotometer (The Perkin Elmer company make, Lambda950), and Redox, Tv, and Te were calculated | required. The results are shown in Tables 1 and 2.

[Examples 2 and 6]
Melting condition B:
Mixing various glass matrix composition raw materials such as silica sand, cullet of high transmission glass plate with TCO film, Sb ₂ O ₃ , oxidizing agent (NaNO ₃ ), refining agent (SO ₃ ) so as to have the composition shown in Table 1. Then, a glass raw material was prepared. The glass raw material was put into a crucible, heated at 1500 ° C. for 3 hours in an electric furnace, then cooled to 1100 ° C. over 2 hours, and held at 1100 ° C. for 1 hour to obtain a molten glass. Molten glass was poured onto a carbon plate and cooled. Both surfaces were polished to obtain a glass plate having a thickness of 4 mm. About the glass plate, the transmittance | permeability was measured for every 1 nm using the spectrophotometer (The Perkin Elmer company make, Lambda950), and Redox, Tv, and Te were calculated | required. The results are shown in Table 1.

In the table, [%] of the charged amount and the composition is a mass percentage display.
The high-transmission glass plates of Examples 4 to 12 of the present invention had redox suppressed by Sb ₂ O ₃ , and Te showed a value close to that of Example 1 in which the cullet of the high-transmission glass plate with a TCO film was not used.
Since the glass plates of Examples 2 and ₃ did not contain Sb ₂ O ₃ , Redox was high and Te was low. The glass of Example 2 exhibits a particularly high Redox value. This is because the increase in Redox due to SnO ₂ proceeds in the glass cooling process, and in Example 2, the glass cooling rate is slow. In Example 6, the cooling rate of the glass is slow as in Example 2, but it can be seen that the increase in Redox does not occur because Sb ₂ O ₃ is added. When Sb ₂ O ₃ is added in this way, a low redox glass can be obtained without worrying about cooling conditions.

FIG. 1 is a graph showing the relationship between Redox and Te in Tables 1 and 2.
Example 1 (without tin and antimony) is a reference example,
Examples 2 and 3 (containing tin and no antimony) are comparative examples,
Examples 4 to 12 (including tin and antimony) are shown as examples.

  In the reference example of the composition not containing tin, Redox is as low as 12.7% and Te is as high as 91.2%. In the comparative example including tin and not including antimony, Redox is as high as 23% or more, and Te is lower than 90.8%. The composition containing tin and antimony of the present invention can have a redox value in the low range of 9.5% to 22.6%, resulting in a high Te.

  Conventionally, redox is increased by tin mixed in when a highly transmissive glass plate with a TCO film is recycled, and as a result, light in the near infrared region of the absorption wavelength band of divalent iron is absorbed by the glass. If the amount of light that passes through the glass in the near-infrared region is simply expressed as Te, Te will decrease in the above-described conventional recycling composition.

  In the present invention, even if tin is contained as shown in the graph of FIG. 1, the redox can be lowered by adding an antimony component, and as a result, a glass having a high Te can be obtained. Since Te is high, that is, there is little absorption in the near infrared region, it is preferable as a solar cell substrate having a crystalline silicon power generation layer with good power generation efficiency with light in the near infrared region.

The manufacturing method of the highly permeable glass plate of this invention is useful as a method which can recycle the cullet of the highly permeable glass plate with a TCO film | membrane as a raw material of a highly permeable glass plate.
In particular, in the float process for forming a TCO film in the middle of a glass manufacturing process, the cullet glass with a TCO film generated during manufacturing is reused as a raw material in a factory for forming a TCO film containing tin oxide in the glass manufacturing process. Can do. This cullet processing in the same factory can reduce the cost of collecting and moving the cullet, and can reduce impurities mixed in the cullet.

Claims (3)

A method for producing a highly transmissive glass plate, comprising melting and forming a glass raw material containing a cullet of a highly transparent glass plate having a transparent conductive film containing SnO ₂ on its surface in a mass percentage display of more than 0% and 80% or less,
The highly transmissive glass plate after molding contains 0.0001 to 0.3% of all antimony converted to Sb ₂ O ₃ in terms of oxide-based mass percentage,
Highly transmissive glass plate after molding
JIS R 3106 (1998) prescribed visible light transmittance (by A light source) is 91.5% or more in terms of 4 mm thickness conversion,
The solar radiation transmittance defined in JIS R 3106 (1998) is 90.9% or more in terms of 4 mm thickness conversion value.
A method for producing a highly transmissive glass plate. The high-transmission glass plate after molding is a mass percentage display based on oxide,
SiO _2: 65~80%,
Al ₂ O _3: 0~5%,
MgO: 0 to 12%,
CaO: 0 to 15%,
Na ₂ O: 5~20%,
K ₂ O: 0~10%,
_{Na 2 O + K 2 O:} 5~20%,
Total sulfur converted to SO ₃ : 0.05 to 0.5%,
Total iron converted to Fe ₂ O ₃ : 0 to 0.04%,
Total antimony converted to Sb ₂ O ₃ : 0.0001 to 0.3%,
Total tin converted to SnO ₂ : 0.005 to 0.2% included,
Fe 2 divalent weight ratio of iron in terms of Fe ₂ O ₃ in the total iron in terms of ₂ O ₃ is 30% or less, the method of producing a high transmittance glass sheet according to claim 1. In mass percentage display based on oxide,
SiO _2: 65~80%,
Al ₂ O _3: 0~5%,
MgO: 0 to 12%,
CaO: 0 to 15%,
Na ₂ O: 5~20%,
K ₂ O: 0~10%,
_{Na 2 O + K 2 O:} 5~20%,
Total sulfur converted to SO ₃ : 0.05 to 0.5%,
Total iron converted to Fe ₂ O ₃ : 0 to 0.04%,
Total antimony converted to Sb ₂ O ₃ : 0.0001 to 0.3%,
Total tin converted to SnO ₂ : 0.005 to 0.2% included,
Mass percentage of divalent iron in terms of _Fe 2 _{O 3} in the total iron in terms of Fe ₂ O ₃ is not more than 30%,
JIS R 3106 (1998) prescribed visible light transmittance (by A light source) is 91.5% or more in terms of 4 mm thickness conversion,
The solar radiation transmittance defined in JIS R 3106 (1998) is 90.9% or more in terms of 4 mm thickness conversion value.
High transmission glass plate.

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