WO2005012963A1

WO2005012963A1 - Method for producing polarizing glass

Info

Publication number: WO2005012963A1
Application number: PCT/JP2004/009910
Authority: WO
Inventors: Yuichi Aoki
Original assignee: Arisawa Mfg. Co., Ltd.
Priority date: 2003-07-31
Filing date: 2004-07-06
Publication date: 2005-02-10
Also published as: JP2005049529A

Abstract

A method for producing a polarizing glass wherein a glass preform containing metal halide particles having a prescribed particle diameter dispersed therein is heated to a prescribed temperature and is subjected to drawing, to form a glass sheet containing drawn metal halide particles, and then said metal halide particles are reduced to metal, to produce a polarizing glass having prescribed polarizing characteristics, characterized in that prior to the heating and drawing of the glass preform, said glass preform is subjected to a heat treatment at a prescribed temperature, to thereby precipitate metal halide particles and simultaneously make its surface to be flatter and its corner portion to have a circular arc form through thermal deformation. The method provides the production of a polarizing glass which can prevent the fracture or breakage during the above drawing process at a reduced cost.

Description

Specification

Manufacturing method of polarizing glass

Technical field

The present invention relates to a method for producing a polarizing glass.

Background art

Polarized glass is used in the near infrared region for optical communication applications, especially for polarization-dependent optical isolators.

By the way, in the optical communication field, reliability is particularly important, and the heat resistance, environmental resistance and optical properties required for the polarizing glass used in this field are at a high level. In both cases, the insertion loss is required to be less than 0.1 dB and the extinction ratio is required to be more than 40 dB. Polarized glass has such excellent performance, and with the practical use of blue semiconductor lasers, it has been applied to areas where polarizing films and wirerids were conventionally used, such as high-density optical recording devices and LCD projectors. Is expected.

However, since this area is for consumer use, price is also an important factor. Therefore, as well as technology for improving the performance of polarizing glass, technology for increasing yield and manufacturing at low cost is also required. Have been.

In general, polarizing glass includes a step of dissolving a base material glass containing a halide, a heat treatment step of precipitating metal halide particles in the base material glass, an elongating step of stretching the metal halide particles, and a step of elongating the metal halide particles. It is manufactured by a reduction process and a finish polishing process. The following method is disclosed as a method for extending the glass preform while preventing breakage or rupture of the glass preform in the stretching step.

(1) Tokudokidaira 2-4 0 6 1 9 (USP 4 4 7 9 8 9 and US 4 4 8 6 2 13) has a laminated structure in which a core glass is covered with a thin surface glass. A method is disclosed in which a glass preform is stretched to prevent breakage of glass generated during the stretching process.

(2) to the "No. 3 1 0 5 4 9 1 No." is the Garasupuri foam polishing the opposing two sides even rather small, if stretched in a range of viscosities 2 XI 0 ⁵ Boyes ~ 7 XI 0 ⁷ Boys It is disclosed that elongation can be performed while preventing breakage of glass.

(3) According to Patent No. 3320004, at least a rectangular plate-shaped preform is drawn in order to prevent cracks from being generated at the end of the rectangular plate-shaped preform. A method of drawing a preform in which two surfaces parallel to a direction are etched is disclosed.

Each of the above (1) to (3) is a method for preventing breakage or destruction of the glass preform in the stretching step, but has the following problems.

Although the method (1) can certainly prevent glass breakage, the production of a laminate preform in which the core glass is covered with a thin surface glass depends on the viscosity and heat of the core glass and the surface glass. It is troublesome because it is necessary to consider the expansion rate. In addition, since it is necessary to adjust the shape of the core glass and the surface glass in separate processes, it is inevitable that the cost will increase accordingly.

The method of (2) is cut at this transgression performing stretching while preventing damage to the glass, to stretch in the range of viscosity 2 x 1 0 ⁵ Boyes ~ ⁷ X 1 0 7 Boys It is difficult to obtain excellent optical characteristics. That is, because called halogen stretching of emission of metal particles about 1 X 1 may ◦ performed in viscosity of ⁸ Boyes and this performing stretching while applying sufficient stress to the halogen of the metal particles, the optical properties Although good ones is obtained, if it is 2 XI 0 ⁵ Boi's ~ 7 X 1 0 ⁷ Boi's above the inferior optical characteristics in the method (2) 0.3 〃111 Ya 0. Polishing must be performed precisely using extremely fine abrasive grains of 0.5 zm, which inevitably results in high costs.

Furthermore, since polishing basically forms scratches on the glass surface, there is a problem that minute scratches remain on the glass surface. In particular, since glass is not plastically deformed, if it is stretched with a force of ²⁰⁰ kg / cm2 or more with the surface remaining flawed, the fracture will easily progress due to the concentration of stress on the flaw. I will.

In the method (3), breakage can be prevented by simply smoothing the end of the preform where stress tends to be concentrated by etching. However, although etching is effective for removing impurities adhering to the glass surface, the amount of etching is relatively large, from 100 m to 100 m, so that fine scratches remaining on the surface are small. The surface may eventually be roughened (roughened) by the effects of foreign matter. In particular, the scratches become deeper due to the etching, and the breakage proceeds more easily.

In addition, since the acid solution used for etching is a strong acid or a mixed solution of strong acid and hydrofluoric acid, care must be taken not only in handling, but also sufficient safety measures for processing equipment and waste liquid treatment. Must be taken As a matter of course, the cost is naturally higher. As described above, in the conventional methods (1) to (3), first, the glass serving as the base material is heat-treated to precipitate metal halide particles. In order to prevent breakage or breakage in the stretching process, the stretching process was performed after the laminate processing ((1)), the polishing process ((2)), or the etching process ((3)), etc. But none of them were cheap.

Disclosure of the invention

The present invention solves the above-mentioned problems, and when the metal halide particles are deposited, the removal of the scratches from the glass and the deposition of the metal halide particles are simultaneously performed by a simple method, so that the stretching is performed. The present invention can provide a polarizing glass that can prevent breakage and destruction that occurs during processing at low cost.

The gist of the present invention will be described.

A glass preform in which metal halide particles having a predetermined particle size are dispersed is heated and drawn to a predetermined temperature to form a glass sheet having drawn metal halide particles, and thereafter, the metal halide particles are reduced. A method for producing a polarizing glass having predetermined polarization characteristics by converting the glass preform into a metal by heating the glass preform at a predetermined temperature before heating and stretching the glass preform. In addition, the present invention relates to a method for producing a polarizing glass, wherein the surface of the glass preform is smoothed by heat deformation and the corners are rounded.

Further, in the method for producing a polarizing glass according to claim 1, The present invention relates to a method for producing a polarizing glass, which comprises preheating the glass preform before heat-treating the reform at a predetermined temperature.

Further, in the method for producing a polarizing glass according to claim 1, the present invention relates to a method for producing a polarizing glass, wherein a temperature of the heat treatment is higher than a softening point temperature of the glass.

Further, in the method for manufacturing a polarizing glass according to claim 2, the present invention relates to a method for manufacturing a polarizing glass, wherein a temperature of the heat treatment is higher than a softening point temperature of the glass.

4. The method for producing a polarizing glass according to claim 3, wherein the glass preform is placed on a container having a heat-resistant temperature of about 800 ° C. or more during the heat treatment. It is related to.

5. The method for producing a polarizing glass according to claim 4, wherein the glass preform is placed on a container having a heat-resistant temperature of about 800 ° C. or more during the heat treatment. It is related to

Further, in the method for producing a polarizing glass according to claim 3, the glass preform is placed on a metal having a melting point lower than the temperature of the heat treatment and a specific gravity heavier than the glass during the heat treatment. The present invention relates to a method for producing a polarizing glass.

In the method for manufacturing a polarizing glass according to claim 4, the glass preform is placed on a metal having a melting point lower than the temperature of the heat treatment and a specific gravity heavier than the glass during the heat treatment. The present invention relates to a method for producing a polarizing glass. Further, in the method for producing a polarizing glass according to claim 7, at least one of typical metal elements included in Groups 12 to 16 of the periodic table is employed as the metal. The present invention relates to a method for producing a polarizing glass.

Further, in the method for producing a polarizing glass according to claim 8, at least one of the typical metal elements included in Groups 12 to 16 of the periodic table is employed as the metal. The present invention relates to a method for producing a polarizing glass.

In the production how the polarizing glass according to any one of claims 1-1 0, and wherein the viscosity of the glass preform at the time of heat stretching is 1 XI 0 ⁷ Boyes ~ 1 XI 0 ⁹ Boys The present invention relates to a method for producing a polarizing glass.

Further, in the method for producing a polarizing glass according to any one of claims 1 to 10, an aspect ratio of the metal particles after heating and stretching is 2: 1 or more, and The present invention relates to a method for producing a polarizing glass, wherein the metal halide particles are oriented in a stretching direction. Further, in the method for producing a polarizing glass according to claim 11, the aspect ratio of the metal halide particles after heating and stretching is 2: 1 or more, and the metal halide particles are oriented in the stretching direction. The present invention relates to a method for producing a polarizing glass, characterized in that:

Further, in the method for producing a polarizing glass according to any one of claims 1 to 10, the ratio of the width of the glass preform before and after the heat stretching is 5: 1 to 2: 1. The present invention relates to a method for producing a polarizing glass, which is a feature.

The method for producing a polarizing glass according to claim 11, wherein The present invention relates to a method for producing a polarizing glass, characterized in that the ratio of the glass preform width before stretching and after heating and stretching is 5: 1 to 2: 1. 13. The method for producing a polarizing glass according to claim 12, wherein the ratio of the width of the glass preform before and after the heat stretching is 5: 1 to 2: 1. 14. The method for producing a polarizing glass according to claim 13, wherein the ratio of the glass preform width before and after the heat stretching is 5: 1 to 2: 1. The present invention relates to a method for manufacturing a polarizing glass. Scratches that occur in the glass preform can be removed by simply heating the glass preform at a predetermined temperature at which the surface of the glass can be smoothed and the corners can be turned into an arc, regardless of the processing of the laminate, polishing, or etching. Removal of scratches and the like can be performed, and the processing becomes extremely simple. Since the heating at the predetermined temperature is not particularly performed separately, but is also performed as the heating for the essential metal particle deposition processing, the heating is performed simultaneously with the smoothing of the surface and the arcing of the angle. Investigations are also carried out, which is very efficient in this regard.

As described above, the surface of the glass preform can be smoothed and the corners can be made arcuate without adding new processing equipment and processing steps, and breakage and destruction when the glass preform is stretched by heating can be prevented at extremely low cost. .

Therefore, the present invention can provide a polarizing glass in which breakage or destruction that occurs when a glass preform is heated and stretched is prevented at low cost. BEST MODE FOR CARRYING OUT THE INVENTION

One embodiment of the present invention will be described below.

The polarizing glass of this embodiment can be manufactured by using a known manufacturing method of a polarizing glass (hereinafter, referred to as a conventional method).

In the conventional method, silver, copper or copper, - the gold halide genus material of cadmium such as' dissolved _{_{S i 0 2, B 2 0}} a, together with the glass raw material consisting of a A 1 ₂ 0 _3, the base glass Is prepared. Next, a heat treatment is performed on the base glass to produce a glass preform in which metal halide particles of a predetermined size are precipitated. Then, the metal halide particles are stretched by heating and applying stress to the glass preform, and subjected to a heat reduction treatment in a hydrogen atmosphere, so that the elongated metal halide particles have an aspect ratio suitable for the wavelength used. To have elongated metal particles.

In this embodiment, the steps of the conventional method can be carried out without change except for the step of producing a glass preform.

Hereinafter, this will be described in more detail.

In this embodiment, a glass material and a metal halide material are melted and mixed, and then solidified to form a base material glass. The base material glass is heat-treated to disperse metal halide particles having a predetermined particle size. The glass preform is heated and stretched to a predetermined temperature to form a glass sheet having stretched metal halide particles, and thereafter, the metal halide particles are reduced to form a metal sheet. A method of producing a polarizing glass having predetermined polarization characteristics by heating the glass preform at a predetermined temperature to precipitate metal halide particles before heating and stretching the glass preform. Smoothing the surface of an ohm by thermal deformation and turning the corner into an arc It is.

Metal halide glass is used as the base glass. This base glass is melted (transition temperature of glass is about 520 ° C, softening point is about 690 ° C The glass preform cut out of the base glass into a plate or block was heated to precipitate metal halide particles.

The state of existence of metal halide particles has not been elucidated yet, but metal ions and halogen ions are separately present in the glass preform. It is thought to be particles.

Specifically, by heating the glass preform, the surface of the glass preform is smoothed, the corners are made arcuate, and the halogenated metal particles are precipitated. This heating temperature is preferably set to a temperature higher than the softening point temperature of the glass, that is, about 700 ° C. or more in the present embodiment.

That is, by heating the glass preform surface at a temperature higher than the softening point temperature of the glass, even if there is a flaw on the glass preform surface, the glass preform is softened and the surface is reformed. This smoothing and arcing of the corners are performed, so that this flaw can be removed.

In addition, crystal nuclei are formed in the metal halide particles before the heat treatment temperature is reached, and at the heat treatment temperature, the growth of the metal halide particles is promoted. Particles can be precipitated simultaneously. Furthermore, because the glass preform is free from scratches, the glass preform does not break or break even when stretched at a viscosity of about 1 × 1 ◦ ⁸ vise, so that a polarizing glass with excellent optical properties can be obtained. .

In addition, before the glass preform is subjected to the heat treatment, a preheating treatment at a predetermined temperature for generating the crystal nuclei of the metal halide grains and growing the crystal nuclei may be performed.

That is, when the glass preform is in the form of a thin plate as in this embodiment, the surface can be smoothed, the corners can be made arcuate, and the metal halide particles can be deposited by directly performing the heat treatment. However, when the glass preform is formed into a thick block, the metal halide particles inside the glass preform, which is difficult to conduct heat, are favorably deposited, so that the glass preform is temporarily transformed before the heat treatment. Preheating treatment is performed between the point temperature and the softening point temperature. By performing crystal nucleation and grain growth of metal halide particles, for example, when metallic silver precipitates, red foreign matter or red coloring can be seen on the glass, making it possible to judge the quality of the glass. If the judgment is good, the glass is changed from a block shape to a plate shape, and heat treatment is performed to smooth the surface, make the corners arc, and precipitate the metal halide particles. It can be a form.

In this embodiment, the glass is set in a container having a heat-resistant temperature of about 800 ° C. or more, and the heat treatment is performed. That is, in this embodiment, since the glass preform is formed by the heat treatment including the smoothing of the surface of the glass preform and the arcing of the corners, the container in which the glass preform is placed (placed) is important. Since the heat treatment is performed at a temperature higher than the softening point of the glass, As the heat resistance temperature, a temperature higher than the softening point temperature of this glass is required. This temperature cannot be unambiguously determined because it depends on the desired particle size of the metal halide particles, the shape of the glass preform, the heat treatment time, etc., but is usually 800 ° C or less. A container formed of a material having a heat resistance temperature of 800 ° C. or more may be used.

Further, from the viewpoint of heat formation including smoothing of the surface and arcing of the corner, it is necessary that the surface of the container in contact with the glass preform is flat and the corner is arc-shaped. However, accuracy of several hundred meters is not required. This is because the heat-treated glass preform is stretched to a width of 5: 1 to 2: 1 by a stretching process, then polished to a desired thickness, and cut to a desired size. Therefore, the shape precision of the glass preform itself is not required. Further, the heat treatment may be performed by placing the glass on a metal whose melting point is lower than the heat treatment temperature and whose specific gravity is heavier than glass. The metal used must have a lower melting point than the heat treatment temperature and a higher specific gravity than glass. As such a metal, a typical metal element included in Groups 12 to 16 of the periodic table is excellent. Among them, particularly, since the glass transition point temperature is about 520 ° C and the specific gravity is about 2.4, a metal having a melting point of 40 CTC or less and a specific gravity of 4.0 or more is preferable. . Since typical metal elements are easily oxidized, the surface of the glass preform in contact with the liquid surface where these metals are melted is reduced. For example, when a glass preform containing silver halide particles is placed in a container whose molten metal is tin, silver is reduced and the glass preform turns yellow. However, if the thickness of the glass is sufficiently thicker than that of the silver layer to be reduced, it can be easily removed, so this is not a problem. The aspect ratio that affects the properties of the polarizing glass is the ratio of the major axis to the minor axis of the metal halide particles stretched in the stretching step or the stretched metal particles after the reduction treatment. Therefore, in order to stabilize the characteristics of the polarizing glass, it is preferable that the particle diameters of the precipitated metal halide particles are uniform, and therefore, the temperature of the base glass during the heat treatment is important. However, it is controlled so that the temperature of the surface of the base glass and the inside become uniform, and the precipitate is uniformly formed with the target particle size.

Control methods include installing a fan inside the electric furnace to stir, optimizing the heating, treatment and cooling times of the electric furnace, and devising a method for installing the base material glass. Can be raised. As a result, the standard deviation of the particle size distribution of the precipitated metal halide particles can be set to 10 nm or less.

In this embodiment, the metal halide particles after heating and stretching of the glass preform have an aspect ratio of 2: 1 or more, and the metal halide particles are oriented in the stretching direction. Is set as follows.

Stretching, feeding a glass preform metal halide particles are precipitated in the electric furnace at a constant speed, the glass preform is predetermined viscosity, in concrete terms, it becomes 1 XI 0 ⁷ Boyes ~ 1 XI 0 ⁹ Boys heated to a temperature, conducted at been tensioning device installed in an electric furnace downwardly by adding ^{1 0 0 K g / cm 2} ~ 6 0 0 K g / cm 2 tensile stress. The applied stress can be controlled not only by the viscosity of the glass but also by the feeding speed and the pulling speed of the glass preform.

The applied stress is set to a value that gives the target aspect ratio within a range where the glass preform does not break. Metal halide particles with a small particle size of about 20 nm are difficult to stretch unless the stress is increased. Also, metal halide particles having a large particle size of about 100 nm are easily stretched even with a small stress. Therefore, when a glass preform in which metal halide particles having different particle diameters are distributed is stretched with uniform stress, a glass preform containing various metal halide particles having various aspect ratios depending on the size of the particle size is obtained. Can be produced.

In order to impart polarizing characteristics to the stretched glass preform, it is necessary to reduce at least a part of the stretched metal halide particles in the glass to form the expanded metal particles.

This reduction is usually performed by heat treating the glass in a hydrogen atmosphere. The reduction reaction depends on the ambient temperature and the reduction time. In particular, the ambient temperature is important. If the ambient temperature is high, the reduction treatment time is shortened, but the stretched metal halide particles are re-spheroidized, causing a reduction in the aspect ratio and a deterioration in the extinction ratio. If the ambient temperature is low, spheroidization does not occur, but the reduction process takes a long time, resulting in cost reduction. In addition, depending on the ambient temperature, the spread of the aspect ratio distribution is reduced due to the decrease in the aspect ratio of some of the elongated metal halide particles, and as a result, the band is also narrowed. From these facts, it is preferable that the reduction is carried out at an atmosphere temperature of 400 ° C. or more, preferably in a temperature range of 410 ° C. to 470 ° C. for 1 hour to 12 hours.

The reduction furnace used for the reduction operates at the atmospheric pressure of the hydrogen flow. The hydrogen used in the reduction treatment is burned using a torch after exiting the sample chamber of the reduction furnace, so there is no danger of explosion and high safety. According to the present embodiment described above, it is possible to provide a polarizing glass capable of preventing breakage and destruction occurring when a glass preform is heated and stretched at low cost. Hereinafter, an experimental example in which the effect of the present embodiment has been confirmed will be described.

Experimental example 1

S i 0 ₂ as the base material glass: 5 6. 3 wt%, B 2 0 3: 1 8. 1 wt%, A 1 a 03: 6. 2 wt% 3 K 20: 5. 7 wt%, L i _{2 0:. 1 8 wt%} , N aa 0: 5. 2 wt%, Z r 0 2: 5. 0 wt%, T i 0 a: 2. 0 wt%, C u 0: 0. 0 1 wt %, Ag: 0.24 wt%, C1: 0.14 wt%, Br: 0.14 wt%. The glass transition point temperature was about 520 ° C and the softening point temperature was about 690 ° C. A flat glass of 70 × 500 × 6 mm (width × length × thickness) was cut out from the glass.

As a material for the container on which the glass was placed, a quartz glass plate having a size of 100 × 600 × 10 mm (width × length × thickness) was prepared. A pot bottom shape of approximately 75 x 5 x 10 x 4 mm was formed on this quartz glass plate, and the concave portion was fire-polished using an oxyhydrogen burner to make the surface in contact with the glass flat and angular. Was made into an arc shape to obtain a quartz glass container.

This container was sufficiently washed with an organic solvent to remove foreign substances such as dust attached to the concave portion. And in the container 7 0 X 5 0 0 X

6 mm flat glass was placed. At this time, the tabular glass was transparent, and silver nodogen particles were not precipitated.

Put the container in a heat treatment furnace and raise the temperature from room temperature to 100 ° C / h.

The temperature was raised to 74 ° C. and kept at 74 ° C. for a certain time. Thereafter, the temperature was slowly lowered to room temperature including slow cooling. When the temperature of the container dropped to room temperature, the glass was removed from the container. The glass was generally rounded, approximately 69 x 49 x 5.5 mm. Also, the glass surface has no scratches or patterns that can be seen due to undulations , She was shiny. In addition, the glass was uniformly fairly turbid, and silver halide grains had clearly precipitated.

The obtained glass was drawn as a glass preform. The temperature of the pressurized hot furnace (drawing furnace) to a temperature at which the viscosity of the glass is approximately 1 X 1 0 ⁸ Boise, 2 5 0 K g / cm 2 ~3 5 0 K a g / cm ² stress pressurized forte stretching Was. No breakage or breakage of the glass preform occurred during the stretching, and a glass sheet having a width of about 14 mm and a thickness of about 1.3 mm was obtained. Then, when this glass sheet was subjected to a reduction treatment using hydrogen gas, the extinction ratio was 50 dB or more, and it was confirmed that the precipitation amount of silver halide particles was sufficient.

Experiment 2

From the glass produced in Experimental Example 1, a flat glass having the same size as that of Experimental Example 1 was cut out. The quartz glass container used in Experimental Example 1 was used as the container.

Transparent flat glass was placed in a container and placed in a heat treatment furnace together with the container. The temperature was raised from room temperature to 600 ° C at a heating rate of 200 ° C Zh, maintained at 600 ° C for a certain period of time, and the crystal nuclei of silver halide grains were generated and grown. . Next, the temperature was increased to 720 ° C. at a heating rate of 200 ° C./h, and the temperature was maintained at 74 ° C. for a certain time. After that, the temperature was slowly lowered to room temperature including slow cooling.

The glass removed from the container was generally rounded and glossy, and there were no corners or scratches on the glass surface or any pattern or swelling that could be attributed to the container. The size was about 69 x 49 x 5.5 mm. Further, the glass was evenly clouded uniformly on the glass surface, and silver halide particles were clearly precipitated. The obtained glass as a glass preform, the temperature of the heating furnace (drawing furnace) to a temperature at which the viscosity of the glass is approximately 1 X 1 0 ⁸ Boise, 2 5 0 K g / cm 2 ~ 3 5 OK g / It was stretched by applying a stress of cm ² . No breakage or breakage of the glass preform occurred during stretching, and a glass sheet having a width of about 14 mm and a thickness of about 1.3 mm was obtained. When this glass sheet was subjected to a reduction treatment using hydrogen gas, an extinction ratio of 50 dB or more could be obtained.

Experiment 3

A 70 × 500 × 5 O mm (width × length × thickness) glass block was cut out of the glass produced in Experimental Example 1. The glass block was placed in a 75 × 530 × 5 Omm (width × length × thickness) stainless steel container and placed in a heat treatment furnace. Then, heat treatment was performed at 6 ° C. for a certain time. Although the glass block after the heat treatment was slightly cloudy, no red foreign matter or red coloring was observed, and no metallic silver was precipitated, so it was judged to be a good product.

Next, a flat glass of 65 × 480 × 6 mm (width × length × thickness) was cut out from the heat-treated glass block. This flat glass was uniformly thin and cloudy. Then, they were placed in the container used in Experimental Example 1 and placed in a heat treatment furnace. The temperature was increased to 720 ° C. at a heating rate of 200 ° C./h and kept at 740 ° C. for a certain time. After slow cooling, the glass taken out of the container was uniformly cloudy, and silver halide grains had grown. The glass was rounded and glossy as a whole, and there were no patterns or undulations attributable to corners or scratched containers as in Experimental Examples 1 and 2. The size was about 64 x 478 x 5.5 mm. The obtained glass as a Garasupuri form, the temperature of the heating furnace (drawing furnace) to a temperature at which the viscosity of the glass is about 1 XI 0 ⁸ Boise, 2 5 0 K g / cm 2 ~ 3 5 OK gZ It was stretched by applying a stress of cm ² . No breakage or breakage of the glass preform occurred during stretching, and a glass sheet about 13 mm in width and about 1.3 mm in thickness was obtained. When this glass sheet was subjected to a reduction treatment using hydrogen gas, an extinction ratio of 50 dB or more was exhibited.

Experimental example 4

Mother glass and to _{S i 0 2: 5 6. 6} wt, B 2 0 3: 1 8. 1 wt%, A 1203: 6. lwt%, K 20: 5. 6 wt%, L i 2 0 :. 1 8 wt%, N a 2 0: 4. lwt%, Z r 0 2: 5. 0 wt%, T i 02:. 1 8 wt%, C u 0: 0. 0 0 6 wt%, Glass having a composition of Ag: 0.22 wt%, C 1: 0.24 wt%, and Br: 0.220 wt% was melted. The glass had a transition point temperature of about 500 ° C and a softening point temperature of about 670 ° C.

A glass plug of 70 x 500 x 5 mm (width x length x thickness) was cut out from the glass. This glass block was placed in the stainless steel container of Experimental Example 4 and placed in a heat treatment furnace. And 600. C was heat treated for a certain period of time. The glass block after the heat treatment was colored red. This coloring was the result of the reduction of silver to metal and the precipitation of silver colloid, so it was judged to be defective, and the reduction in yield due to turning the glass in the subsequent process could be prevented.

Experimental example 5

From the glass produced in Experimental Example 1, a flat glass having the same size as that of Experimental Example 1 was cut out. Put tin in the stainless steel container shown in Experimental Example 3. Then, the mixture was heated and melted at about 400 ° C. using an electric furnace, and then solidified again. At that time, the thickness (height) of the tin was about 35 mm, and the surface was smooth. The melting point of tin is about 23 ° C and the specific gravity is about 7.3.

Place the flat glass on the solidified tin, place it in a heat treatment furnace, raise the temperature from room temperature to 700 ° C at a heating rate of 100 ° C / h, Hold for a certain period of time. Then, it was gradually cooled to room temperature.

The removed glass was round at the top and flat at the bottom. And the upper and lower boundaries were rounded. The surface that was in contact with tin was yellow, but there were no scratches or any undulations. The other surfaces were glossy and beautiful. The size was about 7250 × 2 mm. Further, the glass was uniformly cloudy, and silver halide grains were clearly precipitated.

Here, when the thickness of the portion where silver was reduced was examined separately, it was less than 1 mm.

The obtained glass as Garasupuri foam, the temperature of the heating furnace (drawing furnace) to a temperature at which the viscosity of the glass is approximately 1 X 1 0 ⁸ Boise, 2 5 0 K g / cm 2 ~ 3 5 OK g / cm It was stretched by applying a stress of ² . There was no breakage or breakage of the glass preform during stretching, and a glass sheet approximately 15 mm wide and 0.9 mm thick was obtained.

When this glass sheet was subjected to a reduction treatment using hydrogen gas, it showed an extinction ratio of 5 OdB or more. (In addition, both sides of a 0.9 mm thick glass sheet were polished, When the thickness was reduced to 0.2 mm, the yellow colored portion was completely removed.)

From the above experimental examples, it was found that the glass preform was damaged during the stretching process. It is possible to provide a glass preform free from scratches and roughening of the glass surface, which can cause cracks and breakage, and that metal halide particles can be simultaneously precipitated on the glass preform. Was also good.

Claims

The scope of the claims

1. A glass preform having metal halide particles having a predetermined particle size dispersed therein is heated and drawn to a predetermined temperature to form a glass sheet having drawn metal halide particles, and then the metal halide particles are reduced. A polarizing glass having predetermined polarization characteristics by converting the glass preform into a metal by heating the glass preform at a predetermined temperature before heating and stretching the glass preform. And producing the glass preform by thermal deformation to smooth the surface and to make the corners arc-shaped.

2. The method for producing a polarizing glass according to claim 1, wherein the glass preform is preheated before the glass preform is heated at a predetermined temperature.

3. The method for producing polarizing glass according to claim 1, wherein the temperature of the heat treatment is higher than the softening point temperature of the glass.

4. The method for producing polarizing glass according to claim 2, wherein the temperature of the heat treatment is higher than the softening point of the glass.

5. The method for producing a polarizing glass according to claim 3, wherein the glass preform is placed in a container having a heat resistance temperature of about 800 ° C. or more during the heat treatment. .

6. The method for producing a polarizing glass according to claim 4, wherein, during the heat treatment, the glass preform is placed in a container having a heat resistance temperature of about 800 ° C or more. A method for producing a polarizing glass, comprising mounting the polarizing glass.

7. The method for producing a polarizing glass according to claim 3, wherein, during the heat treatment, the glass preform is placed on a metal whose melting point is lower than the temperature of the heat treatment and whose specific gravity is heavier than the glass. Production method.

8. The method for producing a polarizing glass according to claim 4, wherein the glass preform is placed on a metal having a melting point lower than the temperature of the heat treatment and a specific gravity heavier than the glass during the heat treatment. Manufacturing method.

9. The method for producing a polarizing glass according to claim 7, wherein at least one of the typical metal elements included in Groups 12 to 16 of the periodic table is employed as the metal. Glass manufacturing method.

10. The method for producing a polarizing glass according to claim 8, wherein at least one of the typical metal elements included in Groups 12 to 16 of the periodic table is employed as the metal. Method for producing polarizing glass.

1 1. The method of manufacturing a polarizing glass according to any one of claims 1 to 1 0, the viscosity of the glass preform at the time of heat stretching is a 1 X 1 0 ⁷ Po I's ~ 1 X 1 0 ⁹ Boys A method for producing a polarizing glass, comprising:

12. The method for producing a polarizing glass according to any one of claims 1 to 10, wherein an aspect ratio of the metal halide particles after the heat stretching is 2: 1 or more, and the metal halide particles. Are oriented in the stretching direction.

13. The method for producing a polarizing glass according to claim 11, wherein the aspect ratio of the metal halide particles after the heat stretching is 2: 1 or more, and A method for producing a polarizing glass, wherein the metal halide particles are oriented in a stretching direction.

14. The method for producing a polarizing glass according to any one of claims 1 to 10, wherein a ratio of a glass preform width before and after the heat stretching is 5: 1 to 2: 1. Characteristic method for producing polarizing glass.

15. The method for producing a polarizing glass according to claim 11, wherein the ratio of the glass preform width before and after the heat stretching is 5: 1 to 2: 1. Method.

16. The method for producing a polarizing glass according to claim 12, wherein the ratio of the glass preform width before and after the heat stretching is 5: 1 to 2: 1. Method.

17. The method for producing a polarizing glass according to claim 13, wherein the ratio of the width of the glass preform before and after the heat stretching is 5: 1 to 2: 1. Method.