JP2005239547A - Infrared-cutting hard glass - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a hard glass capable of sharply cutting infrared rays. <P>SOLUTION: The hard glass is a borosilicate glass having a composition comprising, in terms of mass%, 50 to 80% SiO<SB>2</SB>, 0.5 to 10% Al<SB>2</SB>O<SB>3</SB>, a total Fe content of 0.1 to 5% (in terms of Fe<SB>2</SB>O<SB>3</SB>), 1 to 12% Na<SB>2</SB>O+K<SB>2</SB>O+Li<SB>2</SB>O, 8 to 20% B<SB>2</SB>O<SB>3</SB>, 0.5 to 20% CaO+MgO+BaO+ZnO+Sb<SB>2</SB>O<SB>3</SB>, and 0.1 to 3% F and having an Fe<SP>2</SP>+/Fe<SP>3</SP>+ ratio of 3 to 25 and is endowed with visible light-transmitting and infrared-absorbing characteristics by being prepared by adding a reducing agent being a powder of a metal such as Si, Zn, Al, or Sb to the borosilicate glass to reduce the Fe<SP>3+</SP>to Fe<SP>2+</SP>to the above ratio. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a hard infrared cut glass that is hard glass and has absorption characteristics in the infrared region.

Conventionally, absorption characteristics in the infrared region by Fe ²⁺ ions have been used for heat ray absorption by glass. Fe ²⁺ has an absorption center in the vicinity of a wavelength of 1.1 μm, and phosphate glass that forms Fe ²⁺ stably in glass is used for heat ray absorbing filters and the like. This type of phosphate glass contains a large amount of FeO, and exhibits excellent heat ray absorption characteristics that do not cause absorption in the visible region, but has poor chemical durability in terms of glass structure and viscosity at the time of melting. Therefore, it is difficult to form into a complicated shape because it is low, and it is difficult to use as a window glass, a container, or a glass tube, and the actual application is limited to a narrow range such as a filter.

  For this reason, a method for imparting heat ray absorption characteristics using soda-lime-based glass as a basic glass has been developed, and by using this glass, it has become possible to manufacture lighting lamp bulbs and various containers having heat ray absorption characteristics. This method disclosed in Japanese Examined Patent Publication No. 59-3418 is to obtain a heat-absorbing glass with little absorption in the visible region by selecting the iron content of the glass, the fining agent and the reducing agent components and the amount used. is there.

  On the other hand, in a chemical plant using a photochemical reaction, a method of immersing a light source in a reaction solution in a reaction vessel is used in order to perform the reaction efficiently. As the light source, a mercury lamp, an HID lamp, a xenon lamp, or the like is used, depending on the wavelength of light required for the chemical reaction. In such light sources for chemical plants, the calorific value of the lamp increases as the size of the light source increases, so it is necessary to cool the lamp, and glass water-cooled tubes that isolate the reaction solution from the lamp are used. The cooling of the light source is performed without interrupting the light radiation necessary for the photochemical reaction by circulating cooling water in the water-cooled tube. The water-cooled tube material has sufficient corrosion resistance to the reaction solution, and heat resistance is required for temperature rise, so borosilicate system with excellent heat resistance, chemical durability and light transmission Glass is used.

Japanese Patent Publication No.59-3418

  The effect of the cooling water using the water-cooled tube of the chemical plant light source only prevents the temperature rise of the lamp outer tube due to heat transfer, it does not cut the radiant heat from the lamp, and no reaction solution is required. It turned out to be a factor that brings about a temperature rise. Therefore, if glass having infrared absorption characteristics is used for the water-cooled tube, it is possible to effectively block the heat rays that cause the temperature rise and contribute to the improvement of the reaction yield together with the water-cooling effect.

  However, soft glasses such as the phosphate glass and soda lime glass are insufficient in terms of the corrosion resistance and heat resistance strength against the reaction solution, and are difficult to apply to such applications. On the other hand, it was also considered to impart infrared absorption characteristics to the borosilicate glass currently used in water-cooled tubes, but borosilicate glass capable of effectively cutting only infrared rays has been obtained for the following reasons. Absent.

In general, iron in glass exists in the form of Fe ²⁺ or Fe ³⁺ and has the following equilibrium relationship.

This equilibrium depends on the melting atmosphere, glass composition, melting temperature, melting time and the like. In the case of borosilicate glass, since the basic component contains a large amount of acidic components, it is difficult to increase the ratio of Fe ²⁺ to Fe ³⁺ contained in the glass. Thus, it was impossible to sharply cut the infrared region while keeping the transmittance in the visible region high. Therefore, simply adding Fe to the borosilicate glass has a problem that the water-cooled tube has absorption up to the wavelength range necessary for the photochemical reaction, and the reaction efficiency is lowered.

  The present invention has been made in view of such circumstances, and an object of the present invention is to provide a hard glass excellent in heat resistance and chemical durability and having infrared sharp cutting properties.

In order to achieve the above object, the present invention increases the ratio of Fe ²⁺ contained in the glass by adding Fe ₂ O ₃ to the borosilicate glass and melting it under strong reducing conditions. Is possible.

That is, the present invention is by mass _{percentage, SiO 2 50~80%, Al 2} O 3 0.5~10%, 0.1~5% of the total Fe content as _{Fe 2 O 3, Na 2 O} + K 2 O + Li 2 O _{1~12%, B 2 O 3 8~20} %, CaO + MgO + BaO + ZnO + Sb 2 O 3 0.5~20%, F
It is a hard infrared cut glass having a composition of 0.1 to 3% and a ratio of Fe ²⁺ / Fe ^{3+ in} the glass of 3 to 25.

Glass of the present invention, by mass _{percentage, SiO 2 50~80%, Al 2} O 3 0.5~10%, Fe 2 O 3 0.1~5%, Na 2 O + K 2 O + Li 2 O 1~12% , B ₂ O ₃ 5-20%, CaO + MgO + BaO + ZnO + Sb ₂ O ₃ 0.5-20%, F
In a basic glass batch comprising 0.1 to 3%, 0.1 to 1% of metal powder of a glass constituent element is added as a reducing agent to reduce Fe ³⁺ in the glass to Fe ²⁺ , and Fe ²⁺ / Fe ³⁺ ratio is 3 to 25.

  Furthermore, the hard infrared cut glass of the present invention contains ZnO as an essential component.

The hard infrared cut glass of the present invention has a thermal expansion coefficient of 32 to 60 × 10 ⁻⁷ / K.

  Moreover, it is a manufacturing method of the hard infrared cut glass whose said metal powder is any 1 type or 2 types or more of Si, Zn, Al, and Sb.

Since the glass is a borosilicate glass having a thermal expansion coefficient of 32 to 60 × 10 ⁻⁷ / K, it is excellent in heat resistance and chemical durability. Further, since the total Fe content is 0.1 to 5% by mass as Fe ₂ O ₃ and the ratio of Fe ²⁺ / Fe ³⁺ is 3 to 25, an excellent infrared sharp cutting property by Fe ²⁺ can be obtained. .

  Next, the reason why the glass composition of the present invention is limited to the above range will be described.

SiO ₂ is a main component of glass and is an indispensable component for forming a glass network structure, but if it is less than 50%, the network structure becomes insufficient and the water resistance deteriorates. On the other hand, if it exceeds 80%, the meltability deteriorates. Preferably it is 60 to 76% of range.

Al ₂ O ₃ has the effect of improving the chemical durability of the glass, but if it is less than 0.5%, the effect cannot be obtained, and if it exceeds 10%, glass defects such as striae are liable to occur, which is not preferable. . Preferably it is 1 to 9%.

Alkali metal oxides of Na ₂ O, K ₂ O and Li ₂ O reduce the viscosity of the glass and promote melting, but if the total amount is less than 1%, the effect cannot be obtained, and if it exceeds 12% The coefficient of thermal expansion of glass exceeds 60 × 10 ⁻⁷ / K, and the chemical durability is deteriorated.

Metal oxides such as CaO, MgO, BaO, ZnO, and Sb ₂ O ₃ have the effect of improving the meltability, adjusting the thermal expansion coefficient, and improving the chemical durability due to their presence. If it is less than 0.5%, these effects cannot be expected, and if it exceeds 20%, crystals tend to be generated. Preferably it is 3 to 17% of range.

B ₂ O ₃ can improve the meltability without increasing the thermal expansion coefficient, but if it is less than 5%, the effect cannot be obtained, and if it exceeds 20%, the chemical durability is deteriorated. Preferably it is 8 to 18% of range.

  F acts as a glass melting aid, but if it is less than 0.1%, its effect cannot be expected. If it exceeds 3%, the erosion resistance of the melting furnace becomes stronger and the life of the melting furnace is shortened. This is not preferable because glass precipitates crystals.

Fe ₂ O ₃ is added to give infrared absorption characteristics to the glass, and Fe ³⁺ becomes Fe ²⁺ by the action of the reducing agent and has infrared absorption characteristics, but less than 0.1% is sufficient Infrared absorption effect cannot be obtained, and if it exceeds 5%, the absorption in the visible region is increased, making it unsuitable as a light transmitting material. Preferably it is 0.2 to 2%, More preferably, it is 0.3 to 0.8%.

The thermal expansion coefficient satisfies the required heat resistance strength, and is preferably 32 to 60 × 10 ⁻⁷ / K, more preferably in the range of 45 to 55 × 10 ⁻⁷ / K in consideration of glass moldability and the like. It is.

Since the infrared absorption characteristics as described above are given by Fe ²⁺ ions, the ratio of Fe ²⁺ / Fe ³⁺ is the better sharp cut of higher infrared, the ratio of Fe ²⁺ / Fe ³⁺ is 25 If it exceeds, reduced iron precipitates, which is not preferable. On the other hand, if the ratio of Fe ²⁺ / Fe ³⁺ is less than 3, the infrared sharp cutting property is lost and a sufficient heat ray absorption effect cannot be obtained. A preferable range of the ratio of Fe ²⁺ / Fe ³⁺ is 10-20.

Next, the operation of the glass manufacturing method will be described. As described above, since borosilicate glass contains a large amount of acidic components in its basic components, Fe ³ contained in the glass is used in weak reducing agents such as starch that can provide a sufficient reducing action in phosphate glass. it is difficult to increase the ratio of Fe ²⁺ relative to ^+, it has been difficult to sharp cut the infrared range while maintaining a high transmittance in the visible region as phosphoric acid-based glass. Therefore, in the present invention, a relatively large amount of Fe ₂ O ₃ is contained in the borosilicate glass, and a glass constituent element is added as a reducing agent in the form of metal powder in an amount of 0.1 to 1%. This metal powder is oxidized in molten glass to become a glass component, and exerts a strong reducing action in this process. This makes it possible to increase the ratio of Fe ^{2+ to} Fe ³⁺ , and a glass having both infrared sharp-cut properties while being a borosilicate glass. If the addition amount of the metal powder is less than 0.1%, the reducing action is insufficient for borosilicate glass, and sufficient heat ray absorption characteristics cannot be obtained in the infrared region. This is not preferable because the atmosphere becomes stronger and Fe ₂ O ₃ as a colorant is reduced to deposit black metallic iron.

Further, in the present invention, the metal powder used as the reducing agent is selected and used from the metal component of the glass constituent element, so that a strong reducing action can be obtained and at the same time the reducing agent has no unnecessary influence on the glass. There is. Therefore, Si, Zn, Al, and Sb are preferably used for the glass having the above composition. These metals are incorporated into glass as SiO ₂ , ZnO, Al ₂ O ₃ , and Sb ₂ O ₃ , respectively.

As described above, the glass of the present invention is a hard glass excellent in heat resistance and chemical durability, and has an excellent visible transmittance and infrared sharp cut property by increasing the Fe ²⁺ ratio in the glass. .

  Examples of the present invention will be described below. Each raw material is prepared so that the glass composition shown by the mass percentage in Table 1 is obtained, and the reducing agent shown by the mass percentage in Table 2 is mixed therewith. Next, each of these raw material batches is placed in a 1 liter refractory crucible, melted in a closed pot state at 1400-1420 ° C. for about 8 hours, and then poured into a metal mold and slowly cooled into slices. Thus, a sample polished to a thickness of 2 mm was prepared. The glass of the present invention had good antifoaming properties and could be melted in a pot without difficulty. Separately, a phosphate glass having the composition shown in Table 1 was melted, and a sample similar to the example was prepared as a comparative example.

  With respect to the obtained sample, the spectral transmittance was measured, and the transmittances at wavelengths of 535 nm and 1100 nm are shown in Table 2. In addition, Example No. 3 and no. For the sample No. 6, a spectral transmittance curve is shown in FIG. 1 together with the characteristics of the borosilicate glass having no infrared absorption characteristics conventionally used in water-cooled tubes.

Further, for each glass, the total Fe content and the Fe ³⁺ content were measured by an organic solvent extraction method of wet analysis, and the Fe ²⁺ content was determined by subtracting the Fe ³⁺ content from the total Fe content. Based on this result, the ratio Fe ²⁺ / Fe ³⁺ was calculated and is also shown in Table 2.

  Furthermore, Table 1 shows the results of a constant temperature and humidity test in which each sample is left in an atmosphere of 80 ° C. and 95% humidity for 1000 hours and evaluated by changes in the properties of the glass surface as “weather resistance”.

As can be seen from Tables 1 and 2, the glass according to the present invention has a higher transmittance at 535 nm depending on the ratio of Fe ²⁺ / Fe ³⁺ rather than the content of Fe ₂ O _3. The transmittance is kept low at 1100 nm while maintaining a sufficiently high transmittance in the visible range. Incidentally, Example No. Glass melted without adding a reducing agent to glass No. 1 has a ratio of Fe ²⁺ / Fe ³⁺ of 0.3, and the glass is colored yellowish brown due to a large amount of Fe, so that sufficient absorption in the infrared region is obtained. The transmittance of the entire area has declined without it. Also, as shown in FIG. 1, the transmittance of the glass of this example rapidly decreases from the near infrared region to the infrared region while maintaining the same transmittance as that of the conventional borosilicate glass in the visible region.

From the above, it can be seen that the glass obtained by the method of the present invention has infrared sharp-cut characteristics as a result of an increase in Fe ²⁺ in the glass due to the action of a strong reducing agent. In the above embodiment, an example was shown in which one type of each metal powder was added as a reducing agent, but the same effect was obtained even when two or more types of these metal powders were used in combination.

  Moreover, as a result of the constant temperature and humidity test shown in Table 1, the glass of the comparative example became cloudy on the surface and became unusable as a light transmissive material, whereas the glasses of the examples were all appearances. There was almost no change, and a slight decrease in the transmittance was observed for the “◯” compared to the “◎”, and there was no problem in terms of weather resistance.

  The glass of the present invention can be formed in various ways without changing from the conventional borosilicate glass in terms of not only the thermal expansion coefficient but also other physical properties, and the water-cooled tube can be formed in the same manner as before. . Therefore, when the glass of the present invention is used as a water-cooled tube of a photochemical plant, the radiant heat from the light source lamp is blocked without blocking light in the wavelength region necessary for the reaction, and an unnecessary temperature rise of the reaction solution caused by the light source Can be prevented. In addition to water-cooled tubes, it can be used for various applications that require infrared absorption characteristics, and exhibits superior durability and heat resistance compared to phosphoric acid-based glass and soda-lime-based glass that have been used conventionally.

It is a curve figure which shows the spectral transmittance of the sample glass of the Example of this invention, and the conventional borosilicate type glass.

Explanation of symbols

1 Spectral transmittance curve of conventional borosilicate glass 2 Example No. of the present invention Spectral transmittance curve of the glass of 3 No. 3 of the present invention. Spectral transmittance curve of 6 glass

Claims (4)

By mass _{percentage, SiO 2 50~80%, Al 2} O 3 0.5~10%, 0.1~5% of the total Fe content as _{Fe 2 O 3, Na 2 O} + K 2 O + Li 2 O 1~12%, B ₂ O ₃ 8-20%, CaO + MgO + BaO + ZnO + Sb ₂ O ₃ 0.5-20%, F
A hard infrared cut glass having a composition of 0.1 to 3% and a Fe2 ⁺ / Fe3 ⁺ ratio of 3 to 25 in the glass. By mass _{percentage, SiO 2 50~80%, Al 2} O 3 0.5~10%, 0.1~5% of the total Fe content as _{Fe 2 O 3, Na 2 O} + K 2 O + Li 2 O 1~12%, B ₂ O ₃ 5-20%, MgO + BaO + ZnO + Sb ₂ O ₃ 0.5-20%, F
A hard infrared cut glass having a composition of 0.1 to 3% and a Fe2 ⁺ / Fe3 ⁺ ratio of 3 to 25 in the glass.   The hard infrared cut glass according to claim 1 or 2, which contains ZnO as an essential component. The hard infrared cut glass according to any one of claims 1 to 3, wherein a thermal expansion coefficient is 32 to 60 x ^10-7 / K.

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