JP2014034491A - Method for producing arsenic content-controlled glass and method for measuring arsenic content in glass - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing arsenic content-controlled glass, in which the arsenic content in the glass is measured with high sensitivity and controlled to be 0.1 mass ppm or lower.SOLUTION: In a method for producing the glass having specific composition, the arsenic content is measured by a process comprising the following steps (1)-(4). The step (1) is a glass dissolution step of heating a mixture of a glass sample, a high boiling point acid, potassium permanganate and hydrofluoric acid so that the high boiling point acid still remains in the hot mixture to obtain a first glass solution containing manganese dioxide. The step (2) is a manganese dioxide dissolution step of adding a manganese dioxide reducing agent to the first glass solution to dissolve the manganese dioxide in the first glass solution and obtain a second glass solution. The step (3) is a pre-reduction step of adding a reductant, which reduces a pentavalent arsenic ion to a trivalent arsenic ion, to the second glass solution to obtain a glass solution for measurement. The step (4) is an arsenic content measurement step of measuring the arsenic content of the glass solution for measurement by using a hydride generation method.

Description

  The present invention relates to a glass manufacturing method in which arsenic content is controlled and a method for measuring arsenic content in glass. More specifically, the present invention relates to a method for measuring a small amount of arsenic content in glass with high sensitivity, and a method for producing glass managed using this method so that the arsenic content in glass becomes a very small amount.

  Conventionally, the arsenic content in glass (borosilicate glass) is determined by using a spectrophotometric method defined in JIS R 3105, JIS R 3101, or the titration method defined in ASTM C 169-92. It is measured using. The arsenic content in the glass is preferably a very small amount in consideration of the environmental load.

JIS R 3105 JIS R 3101 ASTM C 169-92

  However, since the measurement of the arsenic content in the glass by the conventional spectrophotometric method or titration method is insensitive, there is a problem in accurately measuring the arsenic content with high sensitivity. An object of the present invention is to provide a method for measuring the arsenic content in glass with high sensitivity and a method for producing glass while controlling the arsenic content in the glass at a mass ratio of 0.1 ppm or less. .

As a result of intensive studies to solve the above problems, the present inventors have found that the arsenic content can be measured with high sensitivity by performing a specific treatment on the glass and using a hydride generation method. Moreover, it discovered that glass could be manufactured using this measuring method, managing the amount of arsenic. That is, the present invention is as follows.
<1> A method for producing a glass including a measurement step of measuring an arsenic content in glass, wherein the arsenic content in the glass is controlled to 0.1 ppm or less by mass ratio,
The measurement process includes the following steps (1) to (4):
(1) Preparing the glass as a glass sample, and melting the glass by heating the glass sample, a high boiling acid, potassium permanganate, and hydrofluoric acid to such an extent that the high boiling acid remains. A glass melting step to obtain a first glass solution comprising manganese dioxide;
(2) A manganese dioxide dissolving step in which a reducing agent for manganese dioxide is added to the first glass solution to dissolve the manganese dioxide in the first glass solution to obtain a second glass solution;
(3) A pre-reduction step of adding a reducing agent that reduces arsenic (V) ions to arsenic (III) ions to the second glass solution to obtain a glass solution for measurement;
(4) Arsenic content measurement step of measuring the arsenic content of the glass solution for measurement using a hydride generation method;
And, wherein the glass by mass percentage based on oxides, SiO ₂ 50 to 75% of _{Al 2 O 3 0.1~24%, B} 2 O 3 0 to 12% of MgO 0 to 8% the CaO 0 to 14.5%, the SrO 0-24%, a BaO from 0 to 13.5%, 0 to 20% of Na ₂ O, 0 to 20% of _{K 2} O, the ZrO ₂ 0 to 5 %, MgO + CaO + SrO + BaO is 5 to 29.5%, and Na ₂ O + K ₂ O is a method for producing glass containing 0 to 20%.

<2> A method for measuring the arsenic content in the glass including the following steps (1) to (4).
(1) Preparing the glass as a glass sample, and melting the glass by heating the glass sample, a high boiling acid, potassium permanganate, and hydrofluoric acid to such an extent that the high boiling acid remains. A glass melting step to obtain a first glass solution comprising manganese dioxide;
(2) A manganese dioxide dissolving step in which a reducing agent for manganese dioxide is added to the first glass solution to dissolve the manganese dioxide in the first glass solution to obtain a second glass solution;
(3) A pre-reduction step of adding a reducing agent that reduces arsenic (V) ions to arsenic (III) ions to the second glass solution to obtain a glass solution for measurement;
(4) An arsenic content measurement step for measuring the arsenic content of the measurement glass solution using a hydride generation method.

  ADVANTAGE OF THE INVENTION According to this invention, the arsenic content in glass can be measured with sufficient sensitivity, and the manufacturing method of the glass managed so that the arsenic content in glass might become trace amount by it can be provided. Moreover, the measuring method which can measure the arsenic content in glass with sufficient sensitivity can be provided.

FIG. 1 is a flowchart showing a typical aspect of the measurement process in the present invention.

<The manufacturing method of the glass of this invention>
The glass production method of the present invention is characterized in that it is a production method having a specific measurement step.
The measurement process in the present invention includes the following steps (1) to (4).
(1) Prepare the glass as a glass sample, and melt the glass by heating the glass sample, high boiling acid, potassium permanganate and hydrofluoric acid to such an extent that the high boiling acid remains. A glass melting step to obtain a first glass solution comprising manganese dioxide;
(2) A manganese dioxide dissolving step in which a reducing agent for manganese dioxide is added to the first glass solution to dissolve the manganese dioxide in the first glass solution to obtain a second glass solution;
(3) a pre-reduction step of adding a reducing agent that reduces arsenic (V) ions to arsenic (III) ions to the second glass solution to obtain a glass solution for measurement;
(4) Arsenic content measurement step of measuring the arsenic content of the glass solution for measurement using a hydride generation method.
Furthermore, the glass produced by the present invention, the SiO ₂ 50 to 75% by mass percentage based on oxides, _{Al 2 O 3 0.1~24%, B} 2 O 3 and 0 to 12%, MgO 0-8% of CaO 0-14.5 percent, SrO 0-24% and BaO 0 to 13.5% 0 to 20% of Na ₂ O, 0 to 20% of _{K 2} O, ZrO ₂ to 0 to 5%, MgO + CaO + SrO + BaO to 5 to 29.5%, and Na ₂ O + K ₂ O to 0 to 20%.

A typical flow of the measurement process in the present invention will be described with reference to FIG. FIG. 1 is a flowchart showing a typical aspect of the measurement process in the present invention, but the present invention is not limited to the aspect shown in FIG.
In the glass melting step (1) in FIG. 1, HClO ₄ , potassium permanganate, (KMnO ₄ ), and hydrofluoric acid (HF), which are suitably used as high-boiling acid, are added to a glass sample. , Mixed and heated to melt the glass. In this step, when HF, H ₂ SiF ₆ , and HClO ₄ are generated and a valence III arsenic ion is present in the glass sample, the arsenic ion is oxidized to a valence V, and manganese dioxide ( A first glass solution containing MnO ₂ ) and V-valent arsenic ions is formed.

In the manganese dioxide dissolution step (2), a reducing agent for manganese dioxide is added to the first glass solution. Thereby, manganese dioxide in the first glass solution is dissolved to obtain a second glass solution.
In the pre-reduction step (3), a reducing agent that reduces arsenic (V) ions to arsenic (III) ions is added to the second glass solution to obtain a glass solution for measurement containing trivalent arsenic ions.
In the arsenic content measurement step of (4), the content of the trivalent arsenic ions in the measurement glass solution obtained in (3) is measured using a hydride generation method.

  The manufacturing method of the glass of this invention includes the measurement process of arsenic content including the step of said (1)-(4), 0.1 ppm by mass ratio of arsenic content in specific glass by this measurement process Glass can be produced while managing the following.

  The glass production method of the present invention requires the above arsenic content measurement step, but the steps other than this step are not particularly limited. For example, the step of obtaining a glass sample can include steps such as a melting step, a refining step, and a forming step, which are the same steps as the conventional glass manufacturing method. There is no restriction | limiting in particular about a melt | dissolution process, a refining process, a formation process, etc.

Furthermore, in the manufacturing method of the glass of this invention, after the measurement process of arsenic content, the arsenic content in glass exceeds 0.1 ppm by mass ratio, and the glass of 0.1 ppm or less by mass ratio. It is preferable to include a sorting step for sorting. In the screening step, by selecting a glass having an arsenic content exceeding 0.1 ppm by mass, a glass having an arsenic content controlled to 0.1 ppm or less by mass can be obtained.
In the screening step, glass having an arsenic content exceeding 0.1 ppm by mass may be reused (remelted) as a part of the raw material in the melting step of glass production.

(Measurement process of arsenic content)
The measurement process of the arsenic content of (1) to (4) will be described in detail for each step.

(1) Glass melting step In the glass melting step of the present invention, glass is prepared as a glass sample, and the glass sample, high-boiling acid, potassium permanganate, and hydrofluoric acid are left in the high-boiling acid. The glass is melted by heating to a degree to obtain a first glass solution containing manganese dioxide.
The acquisition route of glass etc. is not specifically limited. For example, the glass may be a glass in the middle of a general glass manufacturing process including a melting process, a clarification process, and a molding process, or may be a glass after the manufacturing process. Furthermore, the glass may be a glass in a state of being incorporated in another product, or may be a glass in the middle of a manufacturing process of another product. In the present invention, these glasses are prepared as glass samples. The glass composition will be described later.

(1) The glass sample used in the glass melting step is preferably in the form of powder, particularly preferably glass powder obtained by pulverizing glass. Furthermore, it is preferable to use what crushed the glass plate obtained through the formation process as a glass sample.
In pulverizing the glass, it is preferable that the size of the pulverized powder is as uniform as possible in order to facilitate dissolution of the glass. Although the shape of the powder is not particularly limited, it is preferable to use particles that pass through a mesh of 250 μm or less because the finer (1) the glass is more easily dissolved in the glass melting step. However, depending on the composition of the glass, it may react with humidity and carbon dioxide, causing a mass change. Is preferred.
Further, the crushed glass sample is preferably stored in a desiccator or the like in a dry atmosphere to prevent moisture absorption, and if there is a concern about adsorption of carbon dioxide, the desiccator is preferably in a nitrogen atmosphere.
(1) In the glass melting step, the method of pulverizing the glass is not particularly limited, and it is preferable to use an agate mortar in consideration of contamination from the mortar and ease of pulverization. However, since an agate mortar is vulnerable to impact and easily cracks, it is preferable to use an alumina mortar when coarsely pulverizing a glass plate, and an agate mortar when further finely pulverizing.

  (1) There is no restriction | limiting in particular in the quantity of the glass sample used for a glass melt | dissolution step, 0.05-2g is preferable. If it is this range, an unmelted residue will not generate | occur | produce and it can melt | dissolve even when the salt derived from a glass composition component produces | generates. In addition, (4) an arsenic concentration sufficient for quantification can be obtained in the glass solution for measurement in the arsenic amount measurement step. The amount of the glass sample is more preferably 0.1 to 1 g, and further preferably 0.3 to 0.5 g.

  The high boiling acid is used for sufficiently volatilizing Si, B, etc., which can react with hydrofluoric acid or hydrofluoric acid to form a volatile compound. The high-boiling acid is also used to generate glass components and soluble salts that remain without volatilization.

  As the high-boiling acid, an acid having a boiling point of 150 ° C. or higher at atmospheric pressure is preferable, and specifically, perchloric acid, sulfuric acid and the like are particularly preferable. The acid is appropriately changed depending on the composition of the glass to be obtained, and it is particularly preferable to use perchloric acid when the target glass contains a large amount of SrO, BaO and the like.

  Containing a large amount of SrO, BaO or the like depends on the composition of the glass and the amount of high-boiling acid used, but in the composition of the glass, SrO is 1% by mass (hereinafter simply referred to as “%”) and / or This refers to the case where BaO is 0.1% or more. If the glass contains a large amount of SrO and / or BaO and sulfuric acid is used as the high boiling acid, it reacts with sulfuric acid to form a sulfate, which is difficult in the (1) glass melting step. There is a tendency to become soluble. Therefore, it is preferable to use perchloric acid.

  As for the usage-amount of the high boiling point acid, 500-5000 mass parts is preferable with respect to 100 mass parts of glass samples. When the amount is within the range, hydrofluoric acid or an element that reacts with hydrofluoric acid to produce a volatile compound (Si, B, etc.) can be sufficiently volatilized. It is also preferable from the viewpoint of the volatilization time of the acid. The more preferable usage-amount of an acid is 1000-3000 mass parts with respect to 100 mass parts of glass samples, More preferably, it is 1000-2000 mass parts.

(1) Potassium permanganate used in the glass melting step is added to oxidize arsenic during heating and to change the valence of arsenic to V. In the present invention, arsenic is easily volatile during heating. Therefore, in order to accurately measure the arsenic content in the glass, in the present invention, (1) arsenic is used as a V-valent ion in the glass melting step. is important.
In general, HNO ₃ is known as an oxidizing agent that oxidizes arsenic. However, since potassium permanganate is used in the present invention, (1) it is not necessary to use HNO _{3 in the} glass melting step. This is because potassium permanganate has a sufficient oxidizing power as compared with nitric acid.

  As for the usage-amount of potassium permanganate, 1-50 mass parts is preferable with respect to 100 mass parts of glass samples. When the amount is within the range, the total arsenic in the glass can be made V-valent, and the amount of manganese dioxide generated during heating can be suppressed. A more preferable usage amount is 3 to 20 parts by mass, and further preferably 5 to 10 parts by mass with respect to 100 parts by mass of the glass sample.

(1) Hydrofluoric acid used in the glass melting step is used for cutting a Si—O—Si bond, which is the main structure of glass, and melting a glass sample.
As for the usage-amount of hydrofluoric acid, 500-5000 mass parts is preferable with respect to 100 mass parts of glass samples. The range of the usage fee can suppress the generation of unmelted residues. Moreover, since it becomes easy to melt | dissolve a glass sample, it is preferable from a viewpoint of the volatilization time of hydrofluoric acid. A more preferable usage amount is 1000 to 3000 parts by mass, and more preferably 1000 to 2000 parts by mass with respect to 100 parts by mass of the glass sample.

  The container, stirrer, and the like used in each step of the present invention are made of an inert material that does not affect the measurement of the arsenic content in each step (1) to (4). For example, in the (1) glass melting step, a glass sample, a high-boiling acid, permanganic acid, and hydrofluoric acid are heated, so that it can withstand at least the acidic conditions of high-boiling acid and hydrofluoric acid. It is necessary to use a container having characteristics. Moreover, since it is preferable to perform a heating at 150-300 degreeC, the container which has heat resistance which can endure this temperature is preferable. The container is preferably made of a material having a heat resistant temperature of 200 ° C. or higher, more preferably 300 ° C. or higher.

  In particular, in the (1) glass melting step, it is preferable to use a container having acid resistance and heat resistance having durability under acidic conditions and high temperature conditions. Preferred examples of the container include a fluororesin container and a ceramic container. As the fluororesin container, a container made of PTFE (polytetrafluoroethylene), PFA (tetrafluoroethylene / perfluoroalkyl vinyl ether copolymer) or the like is preferable, and a container made of PTFE is particularly preferable. As the ceramic container, a container made of alumina, alumina nitride or the like is preferable.

  (1) In the glass melting step, it is preferable to add potassium permanganate before hydrofluoric acid as the order of adding the glass sample, high boiling acid, potassium permanganate and hydrofluoric acid. . Moreover, you may add and heat the whole quantity of all the components at once. About a high boiling point acid and hydrofluoric acid, it is also possible to add in portions and to heat. When adding a high boiling acid and hydrofluoric acid in a divided manner, it is preferable to wash the wall surface of the container so that the glass sample adhering to the wall surface can be recovered and the accuracy of the arsenic measurement value is increased.

  (1) At the time of heating in the glass melting step, water may be added. By adding water, the glass powder can be moistened and dispersed in water, and the sample can be prevented from being lost due to the glass powder flying. Moreover, it becomes possible to suppress a rapid reaction with the glass sample when hydrofluoric acid is added. The amount of water is preferably about 1 to 5 times the mass of the glass sample.

Heating is performed to such an extent that the high boiling acid remains. Heating to such an extent that a high-boiling acid remains, white smoke is generated by addition of the high-boiling acid, the amount of the acid is ½ or less (volume basis) of the addition amount, and the high-boiling acid It is preferable to carry out such that the amount is more than the amount remaining without being dried.
The generation of white smoke due to the addition of high boiling acid can be confirmed by the state in which the high boiling acid is continuously emitted in the form of mist after the hydrofluoric acid has volatilized. Usually, the generation of white smoke can be visually confirmed. .
The amount of the high boiling acid after heating can be confirmed by a general method. For example, the volume of the container to be used is measured in advance, and the standard for determining the desired amount of the high boiling acid is visually judged. A method is mentioned.
The heating conditions vary depending on the components, amounts, etc. used. Specifically, the temperature is preferably 150 to 300 ° C. under normal pressure, and the time is usually preferably about 30 to 120 minutes. The sample is preferably heated on a sand bath.

In the present invention, (1) in the glass melting step, heating is performed to such an extent that a high-boiling acid remains, so that after the (1) glass melting step is completed, the first glass solution is used as it is in the next (2) manganese dioxide dissolution. Can be used for steps. In addition, in the (1) glass melting step, heating is performed to such an extent that a high-boiling acid remains, so that arsenic can be prevented from evaporating by drying.
(1) In the glass melting step, manganese dioxide is produced from potassium permanganate, and a first glass solution containing manganese dioxide, glass, and a high-boiling acid is produced.
The first glass solution thus obtained is subjected to a (2) manganese dioxide dissolution step.

  The first glass solution may be used as it is in the (2) manganese dioxide dissolution step, or a process of collecting the first glass solution adhering to the wall surface of the heated container may be performed. For example, after the first glass solution is cooled, it is also preferable to perform a post-treatment such as washing the wall surface in the container with hydrofluoric acid, a high-boiling acid or the like, and heating to such an extent that the acid remains after washing. . In this case, the solution obtained after the post-treatment is used as the first glass solution.

(2) Manganese dioxide dissolution step In the manganese dioxide dissolution step in the present invention, a reducing agent for manganese dioxide is added to the first glass solution to dissolve the manganese dioxide in the first glass solution, and the second glass solution is dissolved. It is a process to obtain.
Manganese dioxide solids may be present in the first glass solution. In this step, a reducing agent for manganese dioxide is added to dissolve the manganese dioxide.

  (2) In the manganese dioxide dissolving step, it is preferable to add hydrochloric acid before adding the reducing agent for manganese dioxide. By adding hydrochloric acid before adding the reducing agent for manganese dioxide, a salt of a high-boiling acid can be formed, and a stable solution in which the salt is dissolved can be formed. The amount of hydrochloric acid added is preferably such that it is about 0.01 to 6 mol / liter in solution.

(2) The reducing agent for manganese dioxide used in the manganese dioxide dissolving step is selected from those that act as a reducing agent for manganese dioxide and that do not react with the glass composition components to form precipitates. preferable. For example, hydrogen peroxide, ascorbic acid, hydroxylamine chloride and the like can be mentioned. In particular, hydrogen peroxide, which is a reducing agent that generates only water (H ₂ O) after the oxidation-reduction reaction, is more preferable.
The amount of the reducing agent relative to manganese dioxide is not particularly limited as long as it can dissolve manganese dioxide. (1) The lower limit is preferably 5 parts by mass with respect to 100 parts by mass of potassium permanganate used in the glass dissolution step. The upper limit is preferably 100 parts by mass. In particular, when the reducing agent is hydrogen peroxide, the lower limit is 5 parts by mass, and the upper limit is preferably 20 parts by mass.

  (2) The amount of hydrogen peroxide used as the reducing agent in the manganese dioxide dissolution step is preferably less than the excess amount with respect to manganese dioxide. Hydrogen peroxide acts as an oxidizing agent for a reducing agent (hereinafter also referred to as “preliminary reducing agent”) that reduces arsenic (V) ions to arsenic (III) ions in the (3) preliminary reduction step. Therefore, when hydrogen peroxide is added excessively, the action of the prereducing agent may be inhibited. (2) The amount of hydrogen peroxide used in the manganese dioxide dissolution step is preferably 5 to 10 parts by mass with respect to 100 parts by mass of potassium permanganate used in (1) the glass dissolution step.

(2) The dissolution of manganese dioxide in the manganese dioxide dissolution step can be confirmed as follows. That is, (1) In the glass melting step, Mn (VII) of potassium permanganate works as an oxidizing agent, and Mn ²⁺ is generated. At the same time, partly brown manganese dioxide (exactly hydrated MnO _z · nH ₂ O) is produced, and manganese dioxide precipitates as a brown solid. The dissolution of manganese dioxide can be visually confirmed when a reducing agent for manganese dioxide is added to the first glass solution, and the brown solid in the solution disappears and a transparent solution is obtained. In the present invention, it is preferable that a transparent solution obtained by performing the confirmation by this method is the second glass solution.
In addition, when the reducing agent used in the (2) manganese dioxide dissolving step is solid, it is preferable to add the reducing agent as an aqueous solution in advance from the viewpoint of easy addition and easy mixing with the hydrochloric acid solution.

(3) Prereduction step (3) In the prereduction step, a reducing agent for reducing arsenic (V) ions to arsenic (III) ions in the second glass solution (hereinafter also referred to as “preliminary reducing agent”). In addition, it is a step of obtaining a glass solution for measurement.

(3) The preliminary reduction step is important in measuring the arsenic content with high sensitivity in the next step. (4) In the hydride generation method in the arsenic amount measurement step, arsenic is quantified as AsH ₃ . The reason is, AsH ₃ generation efficiency of arsenic (V) ions is poor in comparison with AsH ₃ generation efficiency of arsenic (III) ions, arsenic (V) ion and arsenic (III) hydride generation in a state in which the ions are mixed When arsenic is reduced by the method, arsenic (V) ions have a reaction rate of about 50 to 80% compared to arsenic (III) ions.
Therefore, in the arsenic amount measurement step using the hydride generation method, the arsenic (V) ions are reduced to arsenic (III) ions. (3) The preliminary reduction step is an essential process. In the (3) pre-reduction step, in order to measure the arsenic content with high sensitivity in the (4) arsenic content measurement step, it is preferable that all arsenic ions in the glass solution for measurement have a valence of III.

  (3) As the prereducing agent in the prereduction step, potassium iodide, sodium iodide and the like are preferable. Potassium iodide and sodium iodide are capable of reducing arsenic (V) ions, and other elements (specifically, Cu that may be contained as impurities in the raw material during hydride generation). , Transition metals such as Ni and Fe, and noble metals such as Pt, Au and Ag).

However, (1) When potassium iodide is used when perchloric acid is used as the high boiling point acid in the glass melting step, (3) potassium perchlorate having low solubility is generated in the preliminary reduction step, and the subsequent step May not be implemented successfully.
From the above, sodium iodide is preferable as the prereducing agent when perchloric acid is used as the high boiling acid.

The amount of the prereducing agent is preferably 20 to 1000 parts by mass with respect to 100 parts by mass of the glass sample used in (1) the glass melting step. Within this range, there is an advantage that arsenic is sufficiently reduced and the salt concentration in the solution does not increase. The amount of the prereducing agent is more preferably 100 to 1000 parts by mass, and further preferably 200 to 600 parts by mass with respect to 100 parts by mass of the glass sample.
Since the preliminary reduction may take a long time to proceed, it is better to wait for at least 10 minutes, preferably at least 20 minutes, more preferably at least 30 minutes after adding the preliminary reducing agent. After adding the pre-reducing agent, it may be heated. Heating is preferably performed in a water bath, and the temperature is particularly preferably about 80 to 90 ° C. Stirring may be performed during heating, but it may not be performed.

(4) Arsenic content measurement step (4) In the arsenic content measurement step, the arsenic content of the glass solution for measurement is measured using a hydride generation method.
As the hydride generation method, it is preferable to employ any method selected from hydride ICP emission spectroscopy, hydride atomic absorption method, and hydride ICP-MS method.

In the arsenic amount measurement by the hydride generation method, the same pretreatment as in the case of measurement by the normal hydride generation method is performed. The pretreatment includes a first stage of mixing a glass solution for measurement and an acid (for example, HCl) and generation of AsH ₃ by reducing arsenic (III) ions in the glass sample for measurement with nascent hydrogen. It is preferable to carry out the second step of quantifying AsH ₃ by an ICP emission spectroscopic method, an atomic absorption method, or an ICP-MS method. Moreover, it is preferable to use NaBH ₄ (sodium borohydride) for generation of nascent hydrogen in the second stage.
The NaBH 4 _(sodium borohydride) and the amount of HCl, the same amount as conventional hydrogenation generation method can be employed.

As a specific method for measuring AsH ₃ , a method known as measurement of the amount of arsenic in a glass solution for measurement using a hydride generation method can be employed. For example, it can be carried out according to JIS K 0083 metal analysis method in exhaust gas, JIS K 0116 general rules for emission spectroscopic analysis, JIS K 0232 general rules for atomic absorption analysis, JIS K 0133 general rules for high-frequency plasma mass spectrometry, and the like. In addition, the validity of the measurement result of the arsenic amount in the present invention can be proved by comparing with the measurement result of the verification glass sample when a standard solution with a known arsenic amount is added.
According to the present invention, the upper limit of the measured value of the arsenic content is not particularly limited, and is usually several mass%, and the lower limit is 0.05 mass ppm.

(Processes other than the arsenic content measurement process)
Processes other than the arsenic content measurement process will be described.
In the production method of the present invention, as a method of setting the arsenic content in the glass to 0.1 ppm or less by mass ratio, there is a method of using a raw material not containing arsenic and preventing arsenic from being mixed in the production process. Can be mentioned. Examples of the method for preventing arsenic from mixing include a method in which no arsenic-containing component is added.
Glass raw materials may contain impurity levels of arsenic. Therefore, it is desirable to measure the amount of arsenic in advance and select and use a raw material having a low or substantially no arsenic content.
For example, silica sand, which is a glass mother composition raw material, tin oxide, which is a glass fining raw material, and the like may contain arsenic as an impurity, and thus these raw materials are preferably selected.
The glass production method of the present invention can include a melting step, a clarification step, a molding step, and the like, as in the conventional glass production method, and these steps are not particularly limited. In addition, the glass whose arsenic content is measured is preferably screened for a desired quality, and in particular, a screening step for screening glass having an arsenic content in the glass of 0.1 ppm or less by mass ratio. It is preferable to include.

Specifically, in the glass manufacturing method of the present invention, as in the conventional glass manufacturing method, raw materials are prepared so as to have a predetermined glass composition, and a melting step, a fining step, and a forming step are performed.
As the glass plate forming method, a float method and a fusion method (download method) are preferable. In particular, it is preferable to use a float method capable of easily and stably forming a large-area glass plate as the glass plate becomes larger.
Furthermore, in the present invention, an arsenic content measurement step is performed. The measurement process may be performed at the final stage of the glass manufacturing process, or may be performed at an intermediate stage of the glass manufacturing process. That is, the glass sample can employ | adopt the glass extract | collected from the molten glass in a melting process or a refining process, the glass plate in a formation process, or the glass plate after shaping | molding. By performing the arsenic content measurement in the present invention using the measurement sample, a glass having an arsenic content in the glass of 0.1 ppm or less by mass ratio can be produced. Furthermore, in this invention, glass can be manufactured with stable quality by performing a selection process for selecting 0.1 ppm or less of glass from the manufactured glass.

(Glass in the present invention)
The glass obtained by the production method of the present invention has an arsenic content of 0.1 ppm or less in terms of mass percentage, and is expressed in mass percentage on an oxide basis.
The SiO ₂ 50~75%,
Al ₂ O ₃ 0.1-24%,
0 to 12% of B ₂ O ₃
0-8% MgO
0 to 14.5% of CaO,
0-24% SrO,
BaO 0-13.5%,
Na ₂ O 0-20%
K ₂ O 0 to 20%
ZrO ₂ from 0 to 5%,
It is characterized by having a composition containing 5 to 29.5% of MgO + CaO + SrO + BaO and 0 to 20% of Na ₂ O + K ₂ O.

  The glass obtained by the production method of the present invention is a glass having the above composition. The composition of the glass can be expressed by an oxide-based content (unit: mass percentage).

SiO ₂ is a component that forms a glass skeleton, and if it is less than 50% by mass (hereinafter simply referred to as “%”), the heat resistance and chemical durability of the glass are lowered, and the average thermal expansion coefficient may be increased. There is. The content of SiO ₂ is preferably 56% or more, more preferably 58% or more. If SiO ₂ exceeds 75%, the high-temperature viscosity of the glass increases, which may cause a problem that the solubility deteriorates. Preferably it is 73% or less, Furthermore, it is 70% or less, More preferably, it is 66% or less, More preferably, it is 61.5% or less.

Al ₂ O ₃ raises the glass transition temperature and improves weather resistance (solarization), heat resistance and chemical durability. If the content of Al ₂ O ₃ is less than 0.1%, the glass transition temperature may be lowered. Moreover, there exists a possibility that an average thermal expansion coefficient may increase. Preferably it is 10% or more, More preferably, it is 10.5% or more, More preferably, it is 14% or more, Most preferably, it is 15% or more. If Al ₂ O ₃ exceeds 24%, the high-temperature viscosity of the glass increases, and the solubility may deteriorate. Further, the devitrification temperature is increased, and the moldability may be deteriorated. Preferably it is 22.5% or less, More preferably, it is 22% or less, More preferably, it is 18% or less.

B ₂ O ₃ may be contained up to 12% in order to improve the solubility. If the content exceeds 12%, the glass transition temperature tends to decrease or the average thermal expansion coefficient tends to decrease, and the devitrification temperature rises and the glass tends to devitrify, making glass plate formation difficult. The content is preferably 10% or less. In order to increase the strain point, it is more preferably 3% or less, particularly preferably 2% or less.
The content of B ₂ O ₃ is preferably 5% or more, more preferably 7% or more from the viewpoint of improving solubility.

  MgO has the effect of lowering the viscosity at the time of melting the glass and promoting the melting. In order to prevent the high temperature viscosity of the glass from increasing, thereby preventing deterioration of solubility or chemical durability and increase in density, the content of MgO is preferably 2% or more. If the content of MgO exceeds 8%, the devitrification temperature may increase, so it is preferably 6.5% or less, more preferably 5% or less.

  CaO has the effect of lowering the viscosity at the time of melting the glass and promoting the melting. The content of CaO is preferably 14.5% or less, particularly preferably 9% or less, because the average thermal expansion coefficient of the glass may increase.

  SrO has the effect of lowering the viscosity at the time of melting the glass and promoting the melting, so that it is contained. The SrO content is preferably 3% or more, but if it exceeds 24%, the average thermal expansion coefficient of the glass may increase and the density may increase. The SrO content is preferably 15.5% or less, and more preferably 12.5% or less.

  BaO has an effect of reducing the viscosity at the time of melting the glass and promoting the melting. If the content of BaO is more than 13.5%, the average thermal expansion coefficient of the glass may increase and the density may increase. The BaO content is preferably 2.5% or less from the viewpoint of environmental load, and more preferably 2% or less.

Na ₂ O has the effect of lowering the viscosity at the glass melting temperature and facilitating melting. The content of Na ₂ O is 20% or less. When the Na ₂ O content exceeds 20%, the average thermal expansion coefficient tends to increase and the glass transition temperature tends to decrease. Or chemical durability tends to deteriorate.
Na ₂ O is preferably contained when the glass according to the present invention is used for a glass substrate for a solar cell, particularly a glass substrate for a CIGS solar cell. Na ₂ O is a component that contributes to improving the power generation efficiency of the CIGS solar cell, and in particular, Na diffuses into the CIGS layer formed on the glass substrate, thereby improving the power generation efficiency.

K ₂ O has the effect of lowering the viscosity at the glass melting temperature and facilitating melting. The content of K ₂ O is 20% or less. If it exceeds 20%, the glass transition temperature may be lowered, and the average thermal expansion coefficient may be increased. Or, the density may increase.
When using glass as the glass substrate for a solar cell, especially a glass substrate for a CIGS solar cell of the present invention, K 2 _O exhibits the same effect as Na 2 _O. If the content of K ₂ O in the glass is small, K diffusion to the CIGS layer on the glass substrate may be insufficient, and power generation efficiency may be insufficient.

The total amount of Na ₂ O and K ₂ O is preferably 20% or less because the glass transition temperature may be too low.
ZrO ₂ is a component that lowers the viscosity at the time of melting of glass, has an effect of promoting melting, and improves heat resistance and chemical durability. If the content of ZrO ₂ is more than 5%, the devitrification temperature rises and the glass tends to be devitrified, making it difficult to form a glass plate, and the density may increase.

  MgO, CaO, SrO and BaO are combined in an amount of 5% or more in order to improve the weather resistance of the glass. The total amount is 8% or more, more preferably 9% or more, more preferably 10% or more, and further preferably 16% or more. However, if the total amount exceeds 29.5%, the average thermal expansion coefficient and compaction (C) of the glass at 50 to 350 ° C. may increase, so 26% or less is preferable.

Specifically, as the glass obtained in the present invention, in mass percentage display based on oxide,
The SiO ₂ 50~73%,
10.5-24% Al ₂ O ₃
0 to 12% of B ₂ O ₃
0-8% MgO
0 to 14.5% of CaO,
0-24% SrO,
BaO 0-13.5%,
8-29.5% MgO + CaO + SrO + BaO, and
An alkali-free glass having a composition containing 0 to 5% of ZrO ₂ is preferable.

Furthermore, when considering the high strain point, solubility, acid resistance, buffered hydrofluoric acid, and low expansibility, the glass obtained in the present invention is expressed in mass percentage on an oxide basis.
SiO ₂ 58-66%,
Al ₂ O ₃ 15-22%,
5-12% B ₂ O ₃
0-8% MgO
0-9% CaO,
3 to 12.5% of SrO,
BaO 0-2%, and
9-18% of MgO + CaO + SrO + BaO,
An alkali-free glass having a composition to be contained is particularly preferable.

Furthermore, when relaxing the low-expansion condition and considering solubility in particular, the glass obtained in the present invention is expressed in mass percentage on an oxide basis,
The SiO ₂ 50~61.5%,
Al ₂ O ₃ 10.5-18%,
7-10% of B ₂ O ₃
2-5% MgO,
0 to 14.5% of CaO,
0-24% SrO,
BaO 0-13.5%, and
MgO + CaO + SrO + BaO is 16 to 29.5%,
Alkali-free glass having a composition containing is particularly preferred.

Furthermore, when the conditions of buffered hydrofluoric acid resistance are relaxed and the high strain point is particularly taken into consideration, the glass obtained in the present invention is expressed in terms of mass percentage on an oxide basis,
The SiO ₂ 56~70%,
Al ₂ O ₃ of 14.5 to 22.5%,
0 to 3% of B ₂ O ₃
0 to 6.5% MgO,
0-9% CaO,
0 to 15.5% of SrO,
0 to 2.5% BaO, and
MgO + CaO + SrO + BaO: 10 to 26%,
An alkali-free glass having a composition containing is further preferred.
What is necessary is just to adjust the component amount of a raw material suitably in order to obtain glass of a desired composition.

The glass obtained by the present invention may contain components other than those described above. Other components include Li ₂ O; halogen elements such as F and Cl; transition metals such as Ti, V, Cr, Mn, Fe, Co, Ni, Cu and Zn; rare earth elements such as Ce and La; and In And metal elements such as Sn.
The content of the other components in the glass is preferably a trace amount, particularly preferably 1% by mass or less.
The method for measuring the arsenic content in the present invention can be dissolved easily by applying to a glass sample having a specific composition mainly composed of SiO as a glass sample, and has a low quantitation lower limit. By combining the compound generation method, the amount of arsenic can be accurately quantified. This method is an industrially useful method applicable to general-purpose glass.

<Method for Measuring Arsenic Content of the Present Invention>
The method for measuring the arsenic content of the present invention can be carried out by the same method as the above-mentioned arsenic content measuring step in the method for producing glass of the present invention.
About a glass sample, it is preferable that it is glass which has a specific composition obtained with the manufacturing method of the glass of this invention.

  Hereinafter, although an example and a comparative example explain the present invention still in detail, the present invention is not limited to these.

<Example 1>
The raw material was adjusted so that it might become the glass composition shown in Table 1, and the melting process, the clarification process, and the shaping | molding process (float method) were implemented, and the glass A was obtained. Table 1 shows the results of measuring the composition of glass A by the fluorescent X-ray method. The numerical values in Table 1 are values expressed as mass percentages based on oxides (unit:%).

  The obtained glass plate A was coarsely pulverized using an alumina mortar and then pulverized using an agate mortar to 100 μm or less to obtain a glass sample. To 0.5 g of this glass sample, 0.003 g of potassium permanganate, 5 mL of perchloric acid (about 8.4 g), and 10 mL of hydrofluoric acid (about 11.5 g) are added to a PTFE container and heated to 200 ° C. Then, it was visually confirmed that white smoke was generated. Heating was continued while generating white smoke. As a result of continuing the heating until the total liquid amount became 1/2 or less and the perchloric acid amount became about 2 mL, the glass was dissolved to obtain a first glass solution containing manganese dioxide.

Next, 10 mL (about 11 g) of hydrochloric acid (concentrated hydrochloric acid diluted twice with the same volume of pure water) was added to the first glass solution to form a hydrochloric acid solution, and then 0.015 g of hydrogen peroxide solution was added to the second glass solution. A glass solution was obtained.
2 g of sodium iodide was added to the obtained second glass solution, heated in a water bath at 80 to 90 ° C., and allowed to stand for 30 minutes to obtain a glass solution for measurement.

Using a hydride generator (product name HTG-1200, manufactured by SII Nano Technology Co., Ltd.), the glass solution for measurement and 1 mol / L HCl were mixed in the first stage. Next, in the second stage, sodium borohydride (10 g / L) is mixed to generate nascent hydrogen, and arsenic is reduced to generate AsH ₃ , whereby the arsenic content is determined by ICP emission spectroscopy (SII Nanotechnology). It measured using the product name SPS5520 by Corporation | KK. As a result, the arsenic content was 0.1 μg / g (wtppm) or less.

  Next, a verification glass sample was prepared by adding an arsenic standard solution so that the amount of arsenic was 1 μg with respect to 1 g of the glass sample, and the arsenic content value was similarly determined. As a result of obtaining (a value obtained by removing the arsenic content value from the quantitative value) / (amount of arsenic added) = addition recovery rate, it was 105%. From this result, it was found that the value of the arsenic content is appropriate.

<Example 2>
The raw material was adjusted so that it might become the glass composition shown in Table 2, and the melting process, the clarification process, and the shaping | molding process were implemented, and the glass B was obtained. The mother composition was measured by a fluorescent X-ray method. The numerical values in Table 2 are values expressed in terms of oxide-based mass percentage (unit:%).

  As in Example 1, the arsenic content in the glass was quantified. As a result, the arsenic content was 0.38 wtppm. As a result of producing a verification glass sample and measuring the addition recovery rate in the same manner as in Example 1, it was 105%. From this result, it was found that the value of arsenic content is reasonable.

<Comparative Example 1>
In the glass melting step, the arsenic content in the glass was measured in the same manner as in Example 2 except that heating was performed without using perchloric acid. As a result, it was impossible to measure because a slightly soluble salt was produced in the glass melting step.

<Comparative example 2>
In the glass melting step, the arsenic content in the glass was measured in the same manner as in Example 2 except that heating was performed without using potassium permanganate. As a result, the arsenic content was 0.26 wtppm. When a glass sample for verification was prepared and the recovery rate of addition was examined in the same manner as in Example 1, it was found to be 65%, indicating that the value of arsenic content was not valid. The cause is considered to be that arsenic (III) was volatilized during glass melting.

<Comparative Example 3>
In the glass melting step, an attempt was made to measure the arsenic content in the glass in the same manner as in Example 2 except that heating was performed without using hydrofluoric acid, but analysis was not possible because the glass sample did not dissolve.

<Reference example>
In the glass melting step, the arsenic content in the glass was measured in the same manner as in Example 2 except that heating was performed using a Pt container instead of the PTFE container. As a result, the arsenic content was 0.1 wtppm or less. As a result of producing a verification glass sample and measuring the addition recovery rate in the same manner as in Example 1, it was 0%. The cause is considered to be that Pt was dissolved in a trace amount in the glass solution for measurement and interfered with hydride generation in the hydride generation stage.

<Comparative Example 4>
In the glass melting step, the arsenic content in the glass was measured in the same manner as in Example 2 except that heating was performed until perchloric acid as a high-boiling point acid disappeared. As a result, the arsenic content was 0.25 wtppm. As a result of producing a verification glass sample and measuring the addition recovery rate in the same manner as in Example 1, it was found to be 60% and the arsenic content was not appropriate. The cause seems to be that part of the glass sample was dried and arsenic was volatilized.

<Comparative Example 5>
The arsenic content in the glass was measured in the same manner as in Example 2 except that the first glass solution was used in the preliminary reduction step without performing the manganese dioxide dissolution step. As a result, the arsenic content was 0.3 wtppm, which was a value different from Example 2. This is probably because part of arsenic was taken up by manganese dioxide.

<Comparative Example 6>
The arsenic content in the glass was measured in the same manner as in Example 2 except that the arsenic content of the second glass solution was directly measured using the hydride generation method without performing the preliminary reduction step. As a result, the arsenic content was 0.12 wtppm. Furthermore, the addition recovery rate was 30%. The cause is considered to be that the sensitivity of the arsenic content measurement is lowered because V-valent arsenic ions hardly form hydrides.

<Comparative Example 7>
Arsenic content in the glass in the same manner as in Example 2 except that in the arsenic content measurement step, the arsenic content of the glass solution for measurement was measured using an absorptiometric method according to JIS R 3101 instead of the hydride generation method. Was measured. As a result, the measurement was not possible due to poor sensitivity.

  From the above results, the measurement process for determining the arsenic content in the method for producing the glass of the present invention and the measurement method for the arsenic content in the glass adopted a specific measurement process in the glass sample. It can be seen that the quantity can be measured. Moreover, the glass of a useful composition which has the amount of arsenic in a specific range can be manufactured by manufacturing glass through the measurement process in this invention.

  According to the present invention, the arsenic content in glass can be measured with high sensitivity. Moreover, the manufacturing method of the glass managed so that arsenic content in glass might become a trace amount by this measuring method can be provided.

Claims (16)

A method for producing a glass comprising a measurement step of measuring an arsenic content in a glass, wherein the arsenic content in the glass is controlled to 0.1 ppm or less by mass,
The measurement process includes the following steps (1) to (4):
(1) Preparing the glass as a glass sample, and melting the glass by heating the glass sample, a high boiling acid, potassium permanganate, and hydrofluoric acid to such an extent that the high boiling acid remains. A glass melting step to obtain a first glass solution comprising manganese dioxide;
(2) A manganese dioxide dissolving step in which a reducing agent for manganese dioxide is added to the first glass solution to dissolve the manganese dioxide in the first glass solution to obtain a second glass solution;
(3) A pre-reduction step of adding a reducing agent that reduces arsenic (V) ions to arsenic (III) ions to the second glass solution to obtain a glass solution for measurement;
(4) Arsenic content measurement step of measuring the arsenic content of the glass solution for measurement using a hydride generation method;
And, in terms of oxide based mass percentage, SiO ₂ is 50 to 75%, Al ₂ O ₃ is 0.1 to 24%, B ₂ O ₃ is 0 to 12%, MgO is 0 to 8%, CaO is 0 to 14.5%, the SrO 0-24% and BaO 0-13.5% 0 to 20% of Na ₂ O, 0 to 20% of _{K 2} O, the _{ZrO 2 0~5%, MgO + CaO} + SrO + BaO Of 5 to 29.5% and Na ₂ O + K ₂ O containing 0 to 20%.   The glass manufacturing method according to claim 1, wherein in the glass melting step, a glass sample, a high-boiling acid, potassium permanganate, and hydrofluoric acid are added to a fluororesin container or a ceramic container and heated.   The method for producing glass according to claim 1 or 2, wherein the high-boiling acid in the glass melting step (1) is at least one selected from perchloric acid and sulfuric acid.   The reducing agent for manganese dioxide in the manganese dioxide dissolving step (2) is at least one selected from hydrogen peroxide, ascorbic acid and hydroxylamine chloride. Production method.   The method for producing glass according to any one of claims 1 to 4, wherein the reducing agent for arsenic (V) in the preliminary reduction step (3) is at least one selected from potassium iodide and sodium iodide. .   The hydride generation method in the arsenic content measurement step of (4) is any method selected from hydride generation ICP emission spectroscopy, hydride atomic absorption method, and hydride ICP-MS method. The manufacturing method of the glass in any one of. The glass contains, by mass percentage based on the following oxides, the SiO ₂ fifty to seventy-three% of _{Al 2 O 3 10.5~24%, B} 2 O 3 0 to 12% of MgO 0 to 8% Alkaline containing 0-14.5% CaO, 0-24% SrO, 0-13.5% BaO, 8-29.5% MgO + CaO + SrO + BaO, and 0-5% ZrO ₂ It is glass, The manufacturing method of the glass as described in any one of Claims 1-6. The glass contains, by mass percentage based on the following oxides, the SiO ₂ 58 to 66% of _{Al 2 O 3 15~22%, B} 2 O 3 5-12% 0-8% a MgO, CaO 7 to 9%, SrO 3 to 12.5%, BaO 0 to 2%, and MgO + CaO + SrO + BaO 9 to 18%. The manufacturing method of the glass of description. 2 wherein the glass contains, by mass percentage based on the following oxides, the SiO ₂ 50-61.5% of _{Al 2 O 3 10.5~18%, B} 2 O 3 7-10% of MgO 2. An alkali-free glass containing 5%, 0 to 14.5% of CaO, 0 to 24% of SrO, 0 to 13.5% of BaO, and 16 to 29.5% of MgO + CaO + SrO + BaO. The manufacturing method of the glass as described in any one of -6. The glass contains, by mass percentage based on the following oxides, the SiO ₂ 56 to 70% of _{Al 2 O 3 14.5~22.5%, B} 2 O 3 0-3% the MgO 0 to 2. An alkali-free glass containing 6.5%, CaO 0 to 9%, SrO 0 to 15.5%, BaO 0 to 2.5%, and MgO + CaO + SrO + BaO: 10 to 26%. The manufacturing method of the glass as described in any one of -6. The measuring method of arsenic content in glass including the step of following (1)-(4).
(1) Preparing the glass as a glass sample, and melting the glass by heating the glass sample, a high boiling acid, potassium permanganate, and hydrofluoric acid to such an extent that the high boiling acid remains. A glass melting step to obtain a first glass solution comprising manganese dioxide;
(2) A manganese dioxide dissolving step in which a reducing agent for manganese dioxide is added to the first glass solution to dissolve the manganese dioxide in the first glass solution to obtain a second glass solution;
(3) A pre-reduction step of adding a reducing agent that reduces arsenic (V) ions to arsenic (III) ions to the second glass solution to obtain a glass solution for measurement;
(4) An arsenic content measurement step for measuring the arsenic content of the measurement glass solution using a hydride generation method.   The measurement method according to claim 11, wherein in the glass melting step (1), a glass sample, a high boiling acid, potassium permanganate, and hydrofluoric acid are added to a fluororesin container or a ceramic container and heated.   The measuring method according to claim 11 or 12, wherein the high boiling acid in the glass melting step (1) is at least one selected from perchloric acid and sulfuric acid.   The measuring method according to any one of claims 11 to 13, wherein the reducing agent for manganese dioxide in the manganese dioxide dissolving step (2) is at least one selected from hydrogen peroxide, ascorbic acid and hydroxylamine chloride. .   The measuring method according to any one of claims 11 to 14, wherein the reducing agent for arsenic (V) in the preliminary reduction step (3) is one selected from potassium iodide and sodium iodide.   The hydride generation method in the arsenic content measurement step of (4) is any one selected from hydride generation ICP emission spectroscopy, hydride atomic absorption method and hydride ICP-MS method. The measuring method as described in any one of these.

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