JP4553250B2 - Glass manufacturing method and infrared cut filter - Google Patents

Description

The present invention relates to a glass manufacturing method and an infrared cut filter. More specifically, the present invention relates to a method for producing a glass containing P ₂ O ₅ used as an optical glass, an infrared cut filter glass or the like with good quality and industrially advantageously, and the glass obtained by this method. The present invention relates to an infrared cut filter using

Phosphoric acid has long been used as a glass component. In particular, phosphate glass is widely used for filter glass, low melting point glass, and the like because it has optical properties, thermal properties, and chemical properties that are not found in general silicate glass and borosilicate glass.
_{Conventionally,} when manufacturing a glass containing P 2 _{O 5,} as a material for forming the _P 2 _{O 5,} generally _H 3 PO ₄ (orthophosphoric acid) is widely used. This is because phosphoric anhydride (P ₂ O ₅ ) is highly water-absorbing and reacts quickly with moisture in the atmosphere, making it difficult to use as a raw material for multi-component glass. That is, anhydrous phosphoric acid absorbs water even during preparation, and it is difficult to accurately measure the phosphorus component, but normal phosphoric acid that has reacted with a certain amount of water has stable properties and can be accurately prepared.

  However, since orthophosphoric acid is a liquid, it is difficult to prepare and mix with other raw materials, and there is a problem that the preparation and mixing equipment becomes too large particularly in mass-produced glass. Moreover, since it is a liquid, adhesion of the raw material to the measuring instrument and the mixer is large, and the apparatus must be frequently cleaned. Further, when the mixed raw material is introduced into the furnace and melted, since the liquid raw material is used, it is necessary to input the liquid or cake-like raw material with a pump or a scoop. Moreover, since water rapidly evaporates when it is introduced into the furnace, there is a danger of steam explosions, and the raw material is often scattered, making it difficult to stabilize the quality of the glass.

  On the other hand, metaphosphate raw materials are also used for easy preparation, mixing and charging. That is, a metaphosphate raw material is appropriately selected and used according to the phosphorus component and other components. For example, aluminum metaphosphate, barium metaphosphate, calcium metaphosphate, sodium metaphosphate, etc. are widely used. These metaphosphates, unlike normal phosphates, are dry powder raw materials and can be handled in the same manner as ordinary reagent raw materials. That is, it can be prepared by dry weight, dry-mixed, and powdered mixed raw material can be put into the furnace. Therefore, the blending / mixing device may be simple, and there is little risk of scattering and explosion at the time of charging.

  However, since the metaphosphate raw material does not contain moisture, the obtained glass is different in properties from the glass using orthophosphoric acid. In particular, there is a large difference in the redox state of glass. For example, there are problems such as large coloring, poor clarity, and transition element reduction compared to glass using orthophosphoric acid.

By the way, the glass used for the near-infrared absorption filter which is a visibility correction filter of a CCD (solid-state imaging device) used for a color VTR camera or the like adds CuO as a coloring component and utilizes its absorption by Cu ²⁺ ions. In this case, if P ₂ O ₅ is not used as the main component of the glass network former, good absorption by Cu ²⁺ ions is not exhibited. . Therefore, glass obtained by adding CuO to phosphate glass or fluorophosphate glass is used.
However, when the above-mentioned metaphosphate is used as a raw material for forming P ₂ O ₅ in such an infrared absorption filter glass, Cu ²⁺ ions are reduced, and the short wavelength transmittance is likely to be reduced. Problems arise.

Under such circumstances, the present invention is easy to operate and safe for glass containing P ₂ O ₅ of good quality used as optical glass, infrared cut filter glass, etc. It is an object of the present invention to provide an infrared cut filter using a glass produced by this method and the glass obtained by this method.

As a result of intensive studies to achieve the above object, the present inventors have used a phosphate powder raw material having crystal water as a raw material for forming P ₂ O ₅ of the glass component. In addition to being easy to prepare, it was possible to supply water at the time of glass production while being a powder raw material, and obtained the knowledge that the following effects were exhibited.

By supplying water from crystal water, (1) reduction of transition metal ions such as Cu ²⁺ ions and Ti ⁴⁺ ions can be suppressed, and a decrease in short wavelength transmittance can be suppressed. (2) Glass (3) Conventionally used reduction inhibitors such as As, Sb, and nitrates can be reduced, such as bubbles, which are quality defects, and platinum elution by reduction from platinum equipment used in glass production. Since it does not have to be used, it is possible to eliminate the discharge of glass and dust containing As and Sb and to eliminate the nitrogen oxide discharged from the molten glass.
The present invention has been completed based on such findings.

That is, the present invention
(1) In manufacturing an infrared cut filter glass containing P ₂ O ₅ and CuO , a tripolyphosphate powder is used as a phosphate powder raw material having crystal water . Glass manufacturing method,
Is to provide.

The glass production method of the present invention is a method for producing a glass containing P ₂ O ₅ used as optical glass, infrared cut filter glass or the like with high quality, safely and industrially advantageously, and comprising a glass component By using phosphate powder having crystal water as a raw material for forming P ₂ O ₅ , it is easy to prepare a glass raw material, and water from crystal water is supplied at the time of glass production. The effect of.

(1) Reduction of transition metal ions such as Cu ²⁺ ions and Ti ⁴⁺ ions is suppressed, and a decrease in short wavelength transmittance can be suppressed.
(2) It is possible to reduce bubbles, which are quality defects of glass, and elution of platinum due to reduction from a platinum apparatus used for glass production.
(3) Since it is not necessary to use conventionally used reduction inhibitors such as As, Sb, and nitrates, it is possible to eliminate the discharge of glass and dust containing As and Sb, and to discharge from molten glass. Therefore, glass can be produced in an environmentally friendly manner.

In the production method of the glass of the present invention, when producing a glass containing P ₂ O _5, as the glass material for forming the P ₂ O _5, phosphates powdered material having water of crystallization is used.
Crystal water as used in the present invention refers to water contained in a crystal at a constant compounding ratio, which is water that is fixed at a fixed position in the crystal and is necessary for stabilization of the crystal lattice. If it shows a constant water vapor pressure in a certain temperature range and is heated, dehydration occurs stepwise at a specific temperature, and the crystal structure changes accordingly, and the crystal lattice is broken.

This crystal water is divided as follows according to the position in the crystal, the degree of bonding, and the like.
(A) Coordinating water coordinated to a salt ion, that is, a cation as an H ₂ O molecule, and anionic water that is in a strong binding state with the anion and is less likely to be dehydrated than the above coordinated water. (Some compounds have both the above-mentioned coordination water and anionic water in one molecule.)
(B) Lattice water that is present at a certain ratio in order to fill the voids of the crystal lattice without coordination.
(C) Water that is considered to be contained as oxonium ions (H ₃ O ⁺ ) rather than H ₂ O molecules.
(D) Structural water that is contained as OH groups and dehydrated as H ₂ O when heated.

  These powders containing water of crystallization are less likely to be dehydrated than powders containing absorbed water that has absorbed moisture in the atmosphere, and powders containing mixed water (these are usually dehydrated at 100 ° C.), and have a higher temperature for dehydration. Is required.

When manufacturing a glass containing P ₂ O ₅ using a phosphate powder raw material having such crystallization water, the water of crystallization water is supplied when the glass raw material is melted, similarly to the use of normal phosphoric acid. Accurate preparation becomes possible, and the same effect as that of the regular phosphoric acid is exhibited, and the reduction of transition metal ions such as Cu ²⁺ ions and Ti ⁴⁺ ions is suppressed. And since it is a powder raw material, unlike the case of the said regular phosphoric acid, mixing with the glass raw material of other powder is easy, can mix | blend a glass raw material easily, and can manufacture glass safely. it can.

In the present invention, tripolyphosphate powder is particularly suitable as a phosphate powder raw material having crystal water. Tripolyphosphate is a salt formed by replacing hydrogen of triphosphoric acid (H ₅ P ₃ O ₁₀ ) with a metal, and in many cases has crystal water, and the number of crystal water in one molecule is: Varies depending on the type of metal constituting the salt. For example, sodium tripolyphosphate forms a hexahydrate.

  The tripolyphosphate raw material used in the present invention is appropriately selected depending on other components necessary for the glass composition. For example, any raw material capable of forming a tripolyphosphate such as aluminum tripolyphosphate and sodium tripolyphosphate, calcium tripolyphosphate, lithium tripolyphosphate, and barium tripolyphosphate can be used.

The glass composition may be any composition that contains P ₂ O ₅ and other components (metal components constituting the salt of tripolyphosphate) in an amount that can substantially supplement P ₂ O ₅ as a tripolyphosphate. Therefore, a liquid raw material such as orthophosphoric acid is required for a composition in which P ₂ O ₅ still remains even when tripolyphosphate is used. However, even in that case, the amount of orthophosphoric acid used is reduced, so that the effect of suppressing problems such as adhesion during mixing and charging and generation of water vapor can be expected.

The present invention is particularly useful in a glass having a composition in which boric acid and hydroxide are difficult to be introduced, and can also be applied to a fluorophosphate glass.
Thus, by using a phosphate powder raw material having crystal water as a raw material for forming the glass component P ₂ O ₅ , the glass raw material can be easily prepared and water can be supplied during glass production. it can. As a result, reduction of transition metal ions such as Cu ²⁺ ions and Ti ⁴⁺ ions is suppressed, and a decrease in short wavelength transmittance can be suppressed. Therefore, for example, in the production of glass containing CuO as a coloring component, used for an infrared cut filter such as a near-infrared absorption filter that is a visibility correction filter of a CCD used in a color VTR camera or the like, the crystal water is used. It is effective to use the phosphate powder raw material.

  In addition, by supplying water from crystal water at the time of glass production, there is an effect of reducing generation of bubbles which are glass quality defects and elution of platinum by reduction from a platinum apparatus used for glass production. . Furthermore, since it is not necessary to use conventionally used reduction inhibitors such as As, Sb, and nitrates, it is possible to eliminate discharge of glass and dust containing As and Sb, and discharge from molten glass. Since nitrogen oxides can be eliminated, it is advantageous in terms of environmental hygiene.

  In the manufacturing method of the glass of this invention, glass is manufactured by the method similar to the past except using the phosphate powder raw material which has the said crystal water. That is, for example, using raw materials such as tripolyphosphate, metaphosphate, carbonate, nitrate, oxide, and fluoride as appropriate, the raw materials are weighed and mixed to have a desired composition, and then a heat-resistant crucible such as platinum. Dissolves in. After the molten glass is stirred and clarified, the glass is poured out and molded. The formed glass is transferred to an annealing furnace heated in the vicinity of the glass transition point in advance, and gradually cooled to room temperature.

The present invention also provides an infrared cut filter using the glass produced by the above-described method of the present invention.
Examples of the infrared cut filter include a near infrared absorption filter which is a CCD visibility correction filter. For the infrared cut filter, a glass obtained by adding CuO to a phosphate glass or a fluorophosphate glass is usually used.

EXAMPLES Next, although an Example demonstrates this invention further in detail, this invention is not limited at all by these examples.
Example 1
Aluminum tripolyphosphate (AlH ₂ P) so that the glass composition is 78.0% by mass of P ₂ O _5, 11.0% by mass of Al ₂ O ₃ , 7.0% by mass of Li ₂ O and 4.0% by mass of CuO. ₃ O ₁₀ ) 2 hydrate, lithium carbonate (Li ₂ CO ₃ ), lithium metaphosphate (LiPO ₃ ), and copper oxide (CuO) were used. The prepared raw materials were mixed well, melted at 1100 ° C. for 1 hour, clarified and homogenized, and then the glass was poured out on an iron plate. The poured glass lump was transferred to an electric furnace heated near the glass transition point, and gradually cooled to room temperature. The obtained glass was polished to a thickness of 1 mm and then measured in the wavelength range of 200 to 1200 nm using a spectrophotometer according to Japanese Industrial Standard JIS Z8722.
The transmittance measurement results are shown in FIG.

Comparative Example 1
In Example 1, except that it was prepared using aluminum metaphosphate (Al (PO ₃ ) ₃ ), lithium carbonate (Li ₂ CO ₃ ), lithium metaphosphate (LiPO ₃ ), and copper oxide (CuO). 1 was carried out. The transmittance measurement results are shown in FIG.
As can be seen from FIG. 1, the glass of Example 1 has a higher transmittance around 400 nm than the glass of Comparative Example 1. This is because Cu ²⁺ is reduced and hardly becomes Cu ^1+, and there is a large amount of Cu ²⁺ . For example, the glass of this Example 1 is a useful property as a near infrared absorption filter.

The method for producing glass of the present invention is a method for producing glass containing P ₂ O ₅ used as optical glass, infrared cut filter glass or the like with good quality, safely and industrially advantageously. The glass obtained in (1) is suitable for an infrared cut filter.

It is a chart of the transmittance | permeability in the wavelength of 200-1200 nm of the glass obtained in Example 1 and Comparative Example 1.

Claims (1)

Production of infrared cut filter glass characterized in that tripolyphosphate powder is used as a phosphate powder raw material having crystal water when producing glass for infrared cut filter containing P ₂ O ₅ and CuO. Method.

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