JP4633195B1 - Manufacturing method of polarizing glass - Google Patents

Abstract

An object of the present invention is to propose a method for stably and easily producing a high-performance polarizing glass having a relatively wide width by suppressing breakage of a glass preform during drawing without using dangerous chemicals. To do.
A metal oxide thin film is formed on a surface of a glass preform in which metal halide particles or metal particles are dispersed by a liquid phase film forming method. Then, the glass preform on which the metal oxide thin film is formed is drawn.
[Selection] Figure 1

Description

  The present invention relates to a method of manufacturing a polarizing glass used as a polarizer, which is one of important components such as a small optical isolator, an optical switch, or an electromagnetic sensor used for optical communication. More particularly, the present invention relates to a method for producing a relatively wide polarizing glass without causing breakage during drawing.

  Fine metal particles with oriented and dispersed shape anisotropy, for example, glass containing dispersed copper particles and silver particles, become a polarizer because the light absorption wavelength band of the metal differs depending on the incident polarization direction. It has been known. It is also known that such polarizing glass can be produced by reducing the stretched glass containing copper halide particles or glass containing silver halide particles.

For example, Patent Document 1 discloses a method for producing polarizing glass from glass containing copper halide particles. In this method, at a temperature at which the viscosity of the glass containing the copper halide particles is in the range of 10 ⁷ to 10 ¹⁰ Pa · S, the glass halide is stretched, extruded or pressed to elongate the copper halide particles. Then, the copper halide particles are reduced by heat treatment in a reducing atmosphere to produce a polarizing glass containing elongated shape anisotropic metal copper particles.

Furthermore, as a method for improving the manufacturing method of the polarizing glass containing metal particles having the shape anisotropy, a square plate-like glass preform in which metal halide particles are dispersed is etched with an acid aqueous solution such as hydrofluoric acid. Patent Document 2 proposes a method of drawing a line after that.
This method is a method which can be manufactured without causing breakage of the glass preform during drawing by removing minute scratches on the surface of the stretched glass preform by etching. The drawing stress can be applied to about 14.7 to 29.4 MPa, and is an indispensable method for stably producing a polarizing glass having a relatively wide width (for example, around 10 mm).

  Patent Document 3 below describes that the surface of the core glass containing silver halide grains is coated with a glass having low viscosity. In this method, when the core glass passes through the heated portion of the redrawing furnace in the drawing of the core glass, or during the downdraw, the surface glass with low viscosity is liquefied, and the surface scratches of the core glass are filled. .

Japanese Patent No. 2740601 Japanese Patent No. 3320044 JP-B-2-040619

However, in Patent Document 2, the use of hydrofluoric acid is indispensable in order to efficiently remove the polishing scratches on the surface of the glass preform by etching. However, hydrofluoric acid is a poisonous substance that can cause irritation and fingernails when attached to the human body. In addition, it is known that hydrofluoric acid that has entered from the skin reaches the bone with time and chemically reacts with Ca in the bone, thereby causing severe pain.
In addition, hydrofluoric acid is considered to be ecotoxic to aquatic organisms and has a large environmental impact. For this reason, it is stipulated that the use of hydrofluoric acid is carried out under strict management, and the cost of disposal processing and the like is also high.
In recent years, there has been a tendency to place importance on occupational safety and environmental protection in the workplace, and there has been a need to develop alternative technologies that do not require the use of such chemicals.

Moreover, in the method of the above-mentioned patent document 3, it describes that the film thickness of the surface glass which coat | covers core glass is about 3.18 mm. Although the method for forming the surface glass is not described, for the formation of such a thick film, for example, it is necessary to apply and mold glass powder on the core glass, and heat and sinter. It becomes complicated.
Furthermore, a step of preparing a glass raw material for coating, a step of melting the glass raw material to produce glass, and a step of preparing the glass powder by pulverizing the produced glass are required, leading to the application of the glass powder. It takes time to increase the cost.
Further, the film thickness thus formed is likely to be uneven, and it becomes difficult to apply a uniform tension when the glass is stretched later.

  The present invention has been made in view of such a situation. That is, an object of the present invention is to propose a method for stably and easily manufacturing a high-performance polarizing glass having a relatively wide width by suppressing breakage of the glass preform during drawing without using dangerous chemicals. .

In order to solve the above-described problems, a method for producing a polarizing glass according to the present invention includes a step of forming a metal oxide thin film on a glass preform surface in which metal halide particles or metal particles are dispersed by a liquid phase film forming method. Including.
Moreover, the process of drawing the glass preform in which the above-mentioned metal oxide thin film was formed, and the process of reducing the metal halide particle | grains contained in the glass sheet obtained by drawing are included.

According to the present invention, the metal oxide thin film is formed by a liquid phase film forming method. For this reason, for example, a film can be formed by a simple operation such as applying a coating liquid containing a metal oxide thin film raw material to the surface of the glass preform or immersing the glass preform in the coating liquid. Further, in the liquid phase film forming method, a metal oxide thin film having a uniform thickness can be easily formed.
Further, in this method, the coating liquid enters the scratches on the surface of the glass preform, so that the scratches on the surface of the glass preform can be easily filled.
In this method, the film can be formed without using chemicals such as hydrofluoric acid.

According to the present invention, the metal oxide thin film is formed on the surface of the glass preform by the liquid phase film forming method. For this reason, it is possible to fill the scratches on the surface of the glass preform with a simple process, and it is possible to easily suppress breakage during drawing at low cost.
Further, since chemicals such as hydrofluoric acid are not required, the management cost can be reduced and the safety of the operator can be further improved.

FIG. 1A is a schematic diagram showing a cross section of a scratch on a glass preform surface, and FIG. 1B is a schematic diagram showing a cross section of a scratch on a glass preform surface coated with a metal oxide thin film using the present invention. In embodiment of this invention, it is explanatory drawing which shows a mode that a glass preform is extended.

Examples of the best mode for carrying out the present invention will be described below, but the present invention is not limited to the following examples. The description will be made in the following order.
1. Embodiment of Manufacturing Method (1) Formation of Metal Oxide Thin Film (2) Drawing Step (3) Outline Processing / Polishing Step (4) Reduction Step Example

1. Embodiment of Method for Producing Polarized Glass The glass preform used in the present invention is not particularly limited as long as it is a polarizing glass by drawing.
For example, the metal halide particles may be dispersed in the glass member, and may be composed of a known glass base material and metal halide particles.
Examples of the glass base material include silicate glass, borosilicate glass, and borate glass whose glass softening temperature is higher than the melting point of the halide.
Examples of the metal halide particles include silver chloride, silver bromide, silver iodide, copper chloride, copper bromide, copper iodide, gold chloride, gold bromide, gold iodide, platinum chloride, platinum bromide, Examples thereof include platinum iodide.
Further, the glass in which the metal halide particles are dispersed may be produced by a known method.

Further, a glass preform other than the glass preform in which the metal halide particles described above are dispersed may be used.
For example, in Industrial Materials Vol.52, No.12, 2004 (p102-107), Ag ions are diffused into a glass by a ion exchange method on a soda lime glass plate, and then Ag particles are precipitated by heat treatment or the like. It describes that a polarizing glass is produced by stretching this soda-lime glass plate.
In the present invention, a glass preform obtained by diffusing metal ions on a soda lime glass plate by such an ion exchange method and depositing metal particles can also be used. In addition, since the stretched metal particles themselves are dispersed on the surface of the glass sheet obtained by forming a metal oxide thin film on a glass preform manufactured by the ion exchange method and drawing, a halide is not used. No reduction process is required.

(1) Formation of metal oxide thin film In this invention, the thin film formed in the glass preform surface is comprised including a metal oxide. For example, it can be composed of metal oxides such as Li, Na, K, Mg, Ca, Zn, Al, Y, La, Ga, Bi, Ti, Zr, and Nb. Further, in the present invention, the metal oxide includes so-called semi-metal oxides such as Si, B, and P, and the thin film is formed with an oxide such as SiO ₂ , B ₂ O _{3, and} P ₂ O _5. It may be configured. Hereinafter, in the present invention, a film including these metal oxides is referred to as a metal oxide thin film.
The metal oxide thin film may contain an organic functional group.

  The metal oxide thin film is formed by a liquid phase film forming method in which a coating liquid containing the raw material is applied to the surface of the glass preform or the glass preform is immersed in the treatment liquid. As an example, a method for forming a metal oxide by a sol-gel method will be described below.

(I). In the case of a sol-gel method For example, when forming a metal oxide thin film by a sol-gel method, silicon alkoxide (for example, silicon methoxide, silicon ethoxide, silicon propoxide) is used as the above-mentioned Si source among the raw materials of the coating liquid. , Oligomers thereof) or silicon alkoxide derivatives (for example, methyltriethoxysilane, γ-glycidoxypropyltrimethoxysilane, methylvinyldimethoxysilane, 3-aminopropyltriethoxysilane, N- (2-aminoethyl)- 3-aminopropyltriethoxysilane, etc.) can be used.
In addition, other examples include silicone resins (for example, methyl silicone resin, phenyl silicone resin, methyl phenyl silicone resin) and other silicone compounds (for example, isocyanate silane, silicone acetate, etc.).

As other metal sources, for example, alkoxides, alkoxide derivatives, chelate compounds of the corresponding metals, other organic metal compounds, nitrates, acetates, chlorides, sulfates, metals themselves, and the like can be used.
Examples of the metal alkoxide include titanium tetra-n-butoxide, zirconium tetra-n-propoxide, lanthanum tri-i-propoxide, yttrium tri-i-propoxide, niobium pentaethoxide, and trimethyl phosphite. .
Examples of the alkoxide derivative include tri-n-butoxyacetylacetonatozirconium, diisopropoxybisethyl acetate titanium, and the like.
Examples of the chelate compound include titanium tetraacetylacetonate, lanthanum triacetyltonato, lead diacetylacetonate and the like.
Examples of other organometallic compounds include yttrium methacrylate and zirconium methacrylate.
Examples of the nitrate include lithium nitrate, bismuth nitrate pentahydrate, lanthanum nitrate hexahydrate, and the like.
Examples of the chloride include zirconyl chloride and titanium chloride.
Examples of the sulfate include zirconium sulfate and titanium sulfate.

In the present invention, a metal oxide thin film is formed by a sol-gel method using a coating liquid containing these metal sources, and organic solvents and catalysts for preparing the coating liquid are made of known materials. In addition, the coating solution may be prepared by a known method such as a propeller stirrer, a magnetic stirrer, a rotation / revolution mixer, or an ultrasonic oscillator.
In the coating liquid, for example, oxides (eg, SiO ₂ , TiO _2, etc.) and fluoride (eg, MgF ₂ , CaF _2, etc.) fine particles, organic polymers (eg, polyethylene glycol, hydroxypropyl cellulose) are used as additives. Etc.) may be added.
The coating liquid may contain two or more kinds of metal sources, and may form a metal oxide thin film with two or more kinds of metal oxides.

A metal oxide thin film can be formed by applying the above-mentioned coating liquid on the surface of the glass preform, drying and heating.
As the coating method of the coating liquid, for example, a dipping method, a spin method, a spray method, a roll coating method, a screen printing method, an air doctor coating method, a blade coating method, a lot coating method, a bead coating method, a gravure coating method, etc. are used. It's okay.
Further, when using the sol-gel method, it is possible to form a metal oxide thin film by coating the coating liquid in this way. For example, by using a spin coating method or the like, it can be easily applied to a large area. It can be performed.
Moreover, since it is a liquid application, the film can be formed in a very short time as compared with the case of applying and molding glass powder, and a metal oxide thin film can be easily formed at a low cost.

FIG. 1 is a schematic view showing a cross section of a glass preform 1 on which a metal oxide thin film 3 is formed according to the present invention.
As shown in FIG. 1A, the surface of the glass preform 1 is bonded to the metal constituting the glass (for example, Si, Al, B, etc., M represents another metal atom) including the site of the scratch 2 on the surface. Covered with hydroxyl group OH.
When the above-described coating liquid is applied to the surface of the glass preform 1, the coating liquid easily enters the wound 2 and the scratch 2 is filled with the coating liquid.
For example, when the metal source is silicon alkoxide, silanol (≡Si—OH) is generated in the coating solution by hydrolysis of silicon alkoxide as shown in the following formula (1).

このように、シリコンアルコキシドの加水分解物が次々と脱水重縮合することにより、シロキサン結合が３次元的に広がり、図１Ｂに示すように傷２の内部が埋められる。
そして、最終的にはコート液全体が硬化し、ＳｉＯ_２による金属酸化物薄膜３によってガラスプリフォーム表面が被覆される。 Then, the hydroxyl group (≡Si—OH, ═Al—OH, ═B—OH, etc.) on the surface of the glass preform 1 and silanol produced by the above formula 1 in the coating solution undergo dehydration condensation, and the following formula (2) As shown, a metalloxane bond is formed. Particularly in this case, since the metal is Si, a siloxane bond is formed.

In this way, the hydrolyzate of silicon alkoxide successively undergoes dehydration polycondensation, so that the siloxane bond spreads three-dimensionally and fills the inside of the scratch 2 as shown in FIG. 1B.
Finally, the entire coating solution is cured, and the glass preform surface is covered with the metal oxide thin film 3 made of SiO ₂ .

また、その他の金属アルコキシドを金属源として用いる場合においても、同様に例えば加水分解等によって水酸基を有する加水分解物が生じ、これがガラスプリフォーム１表面の水酸基と縮合することによってメタロキサン結合が形成される。そして、重縮合により、このメタロキサン結合が３次元的に次々と形成されることで、ガラスプリフォーム１の傷を埋め、表面を金属酸化物薄膜で覆うことができる。 For example, as shown in the following formula (3), a metalloxane (siloxane) bond may be formed by a condensation reaction without dehydration.

Similarly, when other metal alkoxide is used as the metal source, a hydrolyzate having a hydroxyl group is produced by, for example, hydrolysis, and this is condensed with the hydroxyl group on the surface of the glass preform 1 to form a metalloxane bond. . And this metalloxane bond is formed three-dimensionally one after another by polycondensation, so that the scratch of the glass preform 1 can be filled and the surface can be covered with a metal oxide thin film.

(Ii) Formation of metal oxide by spin-on-glass method In addition to the sol-gel method described above, a metal oxide thin film may be formed by a spin-on-glass method. The thin film formed by the spin-on-glass method generally includes an inorganic type and an organic type. In the present invention, either an inorganic type or an organic type may be formed.
The inorganic coating liquid used in the spin-on-glass method is composed of, for example, silanol (≡Si—OH) as a main raw material. Further, P may be added to suppress the generation of cracks.
Further, an organic coating liquid, for example alkylalkoxysilanes _{(R n -Si (OR) 4} -n, R is a methyl group, an ethyl group, etc., n represents 1 to 3) configured as a main raw material.
These main raw materials are dissolved in an organic solvent such as ethanol. By applying this coating solution onto the surface of the glass preform by a spin coating method, the coating solution easily penetrates into the scratches on the surface of the glass preform. And a coating liquid is hardened by heat-processing.

Also in this case, the glass preform surface is covered with SiO ₂ by causing a condensation reaction between the silanol group in the coating liquid and the hydroxyl group on the glass preform surface. And a metalloxane (siloxane) bond spreads three-dimensionally, so that a flaw can be filled.
Further, when an organic coating solution is used, there are places that do not bond to the surroundings in the three-dimensional structure of SiO ₂ such as Si—R groups. Damage is suppressed.

(Iii) Formation of Metal Oxide Thin Film by LPD Method The LPD (liquid phase precipitation) method is a method for forming a thin film using a ligand substitution (hydrolysis) equilibrium reaction of a metal fluoro complex. In this method, a metal oxide thin film can be formed on the surface of the glass preform simply by immersing the glass preform in the treatment liquid by a self-deposition / growth type film formation reaction in the treatment liquid.

この溶液中に反応開始剤として例えばホウ酸を加えると、下記式５に示すように、ホウ酸がフッ化水素と優先的に反応して安定したホウフッ化物となり、式４における反応が右に進む。

これにより生じた上記式（４）中におけるシラノール基が、ガラスプリフォーム表面の水酸基と上述の式（２）に示した縮合反応を起こすことにより、シロキサン結合が生じ、ガラスプリフォーム表面にＳｉＯ_２が析出する。そして、このシロキサン結合が３次元的に広がっていくことにより、ガラスプリフォーム表面の傷がＳｉＯ_２によって埋められる。 As an example, a case where an SiO ₂ film is formed on the surface of a glass preform will be given.
As the treatment liquid, for example, a hydrofluoric acid saturated with silicon dioxide is used. In this processing solution, it is considered that the equilibrium shown in the following formula (4) has occurred.

When boric acid, for example, is added to the solution as a reaction initiator, boric acid reacts preferentially with hydrogen fluoride to become a stable borofluoride as shown in the following formula 5, and the reaction in formula 4 proceeds to the right. .

The silanol group in the above formula (4) generated thereby causes the condensation reaction shown in the above formula (2) with the hydroxyl group on the surface of the glass preform, whereby a siloxane bond is generated and SiO ₂ is formed on the surface of the glass preform. Precipitates. Then, the scratches on the surface of the glass preform are filled with SiO ₂ by spreading the siloxane bond three-dimensionally.

When the LPD method is used, the metal oxide thin film can be formed on the surface of the glass preform at a low temperature such as 35 ° C. to 40 ° C., and the heat treatment after the film formation is not required, so that the process can be simplified. In the LPD method, HF is generated as in the above formula (4). However, since it reacts immediately with borate ions to generate stable BF ₄ ⁻ , practically there is almost no HF. Therefore, the influence on the environment and the human body can be significantly reduced as compared with the conventional case.

Further, here, has been given a case of coating the glass preform surface by SiO _{2, TiO} 2 are _{other, FeOOH, V 2 O 5,} ZrO 2, SnO 2, ZnO, Nb 2 O 5, Ta 2 O It is also possible to form other metal oxides such as ₅ .
Further, the glass preform surface can also be coated, for example, by _{TiO2-SiO2, Ti x Sn 1} -x O 2, TiO 2 -Fe 2 O 3, oxides of a plurality of metals such as ZrO 2 _-La 2 _{O 3} .

Thus, in the present invention, since the metal oxide is formed on the surface of the glass preform by the liquid phase film forming method, the coating liquid, the treatment liquid, and the like can be infiltrated into the scratches on the surface of the glass preform. For this reason, it is possible to easily fill the scratches on the surface of the glass preform with the metal oxide.
Further, in this method, since it is not necessary to etch the glass preform surface as in the prior art, hydrofluoric acid is not used. For this reason, the safety of the worker is further improved and the load on the environment is also reduced.
Moreover, since this metal oxide thin film is couple | bonded with the glass preform surface by the metalloxane coupling | bonding, it can protect a glass preform more firmly. For this reason, in the present invention, the thickness of the metal oxide thin film can be reduced to 10 μm or less, although it depends on the depth of the scratch on the surface of the glass preform. The film thickness is preferably 1 nm to 5 μm, for example, and more preferably 10 nm to 2 μm. Thus, in the present invention, even a very thin metal oxide thin film can sufficiently suppress the breakage of the glass preform.

(2) Drawing process The glass preform in which the metal oxide thin film is formed by the method described above is stretched in the drawing process. FIG. 2 is a schematic diagram showing a state in which the glass preform 4 is stretched by a drawing process.
The glass preform 4 is held by the feeding device 5 via, for example, a fixing jig 6 and can move downward in FIG. Further, the glass preform 4 is inserted into the heating furnace 7 through the insertion hole 12 provided in the lid 10, and its posture is fixed by the fixing jig 6. By disposing the lid 10, breakage due to a rapid temperature rise of the glass preform 4 and release of heat in the superheating furnace 7 are suppressed.

Further, a heat generating portion 11 is disposed in the vicinity of the discharge hole 13 of the heating furnace 7, and the glass preform 4 is heated and softened. And the softened glass preform 4 is discharged | emitted from the discharge hole 13 by being pulled by the tension | pulling apparatus 8, and the glass sheet 9 in which the extended metal halide particle | grains or the metal particle was disperse | distributed is obtained.
In addition, this heating furnace 7 can adjust the temperature of the heat generating part 11 by a temperature adjusting device (not shown), and the viscosity of the glass preform 4 in the heating furnace 7 can be adjusted by this temperature adjustment.
Further, the aspect ratio of the stretched metal halide particles or metal particles is set to a desired value by adjusting the feeding speed of the glass preform 4 by the feeding device 5 and the pulling speed and tension of the pulling device 8. Is possible.

In the drawing process of the preform in which the metal halide particles are dispersed, the glass obtained by drawing can be cooled particularly efficiently by setting the thickness of the glass obtained by drawing to 1 mm or less, and the elongated metal halide particles. It is possible to prevent re-spheroidization.
Moreover, as such a drawing process, the method described in the said patent document 2 and Unexamined-Japanese-Patent No. 8-231241 can be used, for example.
Moreover, in the drawing process of the glass preform in which the metal particles are dispersed by an ion exchange method or the like, the metal particles are stretched to become an anisotropic shape, thereby exhibiting polarization characteristics. Since this type of polarizing glass usually has a metal particle-containing layer as thin as several μm, it is provided as a polarizing glass simply by cutting it to a predetermined size without grinding and polishing the surface of the glass sheet after drawing.
Therefore, the polishing process and the reduction process described later are performed on a glass sheet obtained by drawing a glass preform in which metal halide particles are dispersed.

(3) Outline processing / polishing process Generally, a glass sheet formed by drawing in a drawing process is cut into, for example, an 11 mm square, ground to a thickness of about 0.2 mm, or lapped in order to obtain a predetermined shape. The outer shape is processed, and the surface is polished to make the thickness uniform.
In polishing, it is preferable to perform optical polishing in order to improve the surface smoothness of the glass sheet. For example, by polishing one surface of several μm to several tens of μm by polishing, the glass sheet surface can be made an optical surface.
In the present invention, the metal oxide thin film on the surface of the glass sheet is removed in the outer shape processing / polishing step. Therefore, the metal oxide thin film formed by the above liquid phase film forming method does not remain on the completed polarizing glass. For this reason, the metal oxide thin film formed in the present invention is not limited in material type by optical characteristics such as light transmittance, and fills scratches on the surface of the glass preform by a liquid phase film forming method. Any material can be used as long as it is.

(4) Reduction process The glass sheet that has undergone the outer shape process and the polishing process is then reduced. Thereby, a part or all of the metal halide particles in the glass sheet become metal particles.
This reduction treatment can be performed, for example, by heat-treating the glass sheet in a reducing gas atmosphere. Examples of the reducing gas include hydrogen gas and CO—CO ₂ gas. The reduction conditions vary depending on the type of metal halide to be reduced. However, if the reduction temperature is too high, the metal particles obtained by reduction will be re-sphericalized. Therefore, the reduction temperature is determined within a range in which the metal particles obtained by reduction do not re-sphericalize. For example, in the case of copper halide, it is appropriate that the temperature is about 350 to 550 ° C.
The reduction time can be appropriately determined in consideration of the reduction temperature and the degree of reduction. Usually, it can be performed in a range of 30 minutes to 10 hours.
By this reduction step, the glass sheet becomes a polarizing glass having a polarizing function.

2. Example Below, the Example of the manufacturing method of the polarizing glass by this invention is described.
<Example 1: Sol - Formation of SiO ₂ film by Gel Method>
(1) Production of glass preform SiO ₂ (59.5 wt%), AlF ₃ (2.0 wt%), Al ₂ O ₃ (6.7 wt%), B ₂ O ₃ (20.3 wt%), Na ₂ A glass having a composition of O (9.6 wt%), NaCl (1.0 wt%), CuCl (0.8 wt%), SnO (0.1 wt%) (in oxide / chloride conversion) having a capacity of 5 L It melt | dissolved at 1410 degreeC with the platinum crucible.
Moreover, the melted glass was poured into a mold and kept at 470 ° C. and gradually cooled to prepare a glass block. Next, this glass block was cut into an appropriate size and heat-treated at 715 ° C. for 5 hours. As a result, glass in which copper chloride particles having an average particle diameter of about 90 nm were dispersed was obtained.
The glass was shaped into a predetermined shape and ground and polished to produce a square plate-like glass preform having a width of 100 mm, a length of 300 mm, and a thickness of 4.5 mm.

(2) Preparation of coating liquid Mixture of tetraethoxysilane {Si (OC ₂ H ₅ ) ₄ , ethyl silicate 28, purity: 99%, abbreviated to TEOS, abbreviated as TEOS} 2627 g and ethanol 1.75 kg under stirring A mixture of 225 g of a 0.15 M hydrochloric acid aqueous solution and 1.75 kg of ethanol was added to the mixture, and the mixture was stirred for 1 hour to hydrolyze tetraethoxysilane.
While stirring, this solution was added to a mixed solution of 900 g of 0.15 M hydrochloric acid aqueous solution and 17.75 kg of isopropanol, and further stirred for 5 hours for hydrolysis and dilution to produce 25 kg of a thin film coating solution. The charged composition of the thin film obtained from this coating liquid is 100 wt% of SiO ₂ , and the solid content in the coating liquid (assuming that it is completely oxidized by heat treatment) is 3.0 wt%. The coating solution was colorless and transparent.

(3) Application of coating liquid This coating liquid was applied to the above glass preform by a dipping method (hereinafter referred to as “V”) with a pulling speed V = 30 cm / min. The obtained thin film was colorless and transparent and homogeneous. This glass preform with a thin film was dried at 100 ° C. for 30 minutes, then placed in a heat treatment furnace, heated to 500 ° C. at 200 ° C./hour, and held at 500 ° C. for 1 hour. The thickness of the thin film after the heat treatment was 0.18 μm, and the thin film after the heat treatment was also colorless and transparent and homogeneous.

(4) Drawing process The glass preform which apply | coated the above-mentioned coating liquid was set to the heating furnace 7 shown in FIG. 2, and it hold | maintained at 720 degreeC for 30 minutes. A wire was wound around the lower end of the glass preform in advance, and after the furnace temperature was stabilized, a load was applied to the wire to start the elongation of the glass.
And the glass sheet which became tape shape by drawing was squeezed in the drive roller of the tension | pulling apparatus 8, and the temperature in a heating furnace was reset to 650 degreeC.
Next, gradually increase the rotation speed of the feeding device 5 and the driving roller, and draw the wire while finely adjusting the temperature of the heating furnace so that the measured tension follows the set tension of 27 kg, and draw the wire without breaking until the end. Finished.
Thus, a tape-like glass sheet having a glass cross-sectional size of approximately 17 mm wide and 0.6 mm thick was obtained. That is, the drawing tension was 265 kgf / cm ² (26.0 MPa).

(5) Outline processing / polishing step and reduction step The obtained tape-shaped glass sheet is cut to a predetermined length, and then ground and polished to a thickness of 0.2 mm, and in an atmosphere of hydrogen gas at 1 atmosphere at 430 ° C. for 6 hours Heat treated. Thereby, the copper chloride particles were reduced at a depth of about 40 μm from both surfaces in the thickness direction of the glass sheet to produce a polarizing glass. The extinction ratio of the obtained polarizing glass was 55 dB when the distance between the polarizing glass and the detector was 300 mm and the wavelength was 1.55 μmm.

<Example 2: Sol - Formation of organic-containing SiO ₂ film by Gel Method>
While stirring a mixed solution of 1751 g of tetraethoxysilane (same raw material as in Example 1) and 1.50 kg of ethanol, 150 g of 0.15 M hydrochloric acid aqueous solution was gradually added and stirred for 2 hours to hydrolyze tetraethoxysilane.
To this hydrolyzed solution, 1499 g of methyltriethoxysilane {CH ₃ Si (OC ₂ H ₅ ) ₃ , LS-1890, purity: 99%, manufactured by Shin-Etsu Chemical Co., Ltd., abbreviated as MTES} is added and stirred for 1 hour. did.

This solution was added to a mixed solution of 1200 g of 0.15 M hydrochloric acid aqueous solution and 18.90 kg of isopropanol under stirring, and further stirred for 4 hours for hydrolysis and dilution to produce 25 kg of a thin film coating solution.
The composition of the thin film obtained from this coating solution is 100 wt% SiO ₂ (SiO ₂ : 50% using tetraethoxysilane as a raw material, SiO ₂ : 50% using methyltriethoxysilane as a raw material). The solid content is 4.0 wt%. The coating solution was colorless and transparent.

This coating solution was applied to a glass preform (width 100 mm × length 300 mm × thickness 4.5 mm) produced in the same manner as in Example 1 at a speed of V = 25 cm / min. The obtained thin film was colorless and transparent and homogeneous.
This glass preform with a thin film was dried at 100 ° C. for 30 minutes, then placed in a heat treatment furnace, heated to 450 ° C. at 200 ° C./hour, and held at 450 ° C. for 30 minutes. The thickness of the thin film after the heat treatment was 0.20 μm, and the thin film after the heat treatment was also colorless and transparent and homogeneous.
Then, the glass preform was subjected to a drawing process, an outer shape processing / polishing process, and a reduction process in the same manner as in Example 1 to produce a polarizing glass without breaking during the drawing process.

<Example 3: Formation of oxide film by two kinds of metals using sol-gel method>
While stirring a mixture of 3635 g of tetraethoxysilane (same raw material as in Example 1) and 3.00 kg of isopropanol, 311 g of 0.15M hydrochloric acid aqueous solution was gradually added and stirred for 3 hours to hydrolyze tetraethoxysilane. .
To this hydrolyzed solution, 1432 g of tri-n-butyl borate {B (OC ₄ H ₉ ) ₃ , purity: 98%, manufactured by Kanto Chemical Co., Ltd.} was added and heated to reflux overnight.

After this solution was cooled to room temperature, it was added to a mixed solution of 1904 g of 0.15M hydrochloric acid aqueous solution and 14.72 kg of isopropanol under stirring, and further stirred for 2 hours to produce 25 kg of a thin film coating solution. The charged composition of the thin film obtained from this coating solution is 17 wt% B ₂ O _{3 and} 83 wt% SiO ₂ , and the solid content in the coating solution is 5.0 wt%. The coating solution was colorless and transparent.
This coating solution was applied to a glass preform (width 100 mm × length 300 mm × thickness 4.5 mm) produced in the same manner as in Example 1 at a speed of V = 25 cm / min using the dipping method. The obtained thin film was colorless and transparent and homogeneous. The glass preform with a thin film was dried at 100 ° C. for 30 minutes, then placed in a heat treatment furnace, heated to 500 ° C. at 150 ° C./hour, and held at 500 ° C. for 30 minutes. The thickness of the thin film after the heat treatment was 0.14 μm, and the thin film after the heat treatment was also colorless and transparent and homogeneous.
Then, the glass preform on which the B ₂ O ₃ —SiO ₂ thin film was formed was subjected to a drawing process, an outer shape processing / polishing process, and a reduction process in the same manner as in Example 1 to produce a polarizing glass. In this example as well, the glass preform did not break during drawing.

<Example 4: When heat treatment is omitted in Example 3>
The coating liquid of Example 3 was applied to a glass preform (width 100 mm × length 300 mm × thickness 4.5 mm) produced in the same manner as in Example 1 at a rate of V = 25 cm / min by the dipping method, and 100 ° C. For 30 minutes. The thickness of the obtained SiO ₂ thin film was 0.30 μm.
In this way, except that the metal oxide thin film was formed on the surface of the glass preform, the same steps as in Example 1 were taken, and a polarizing glass was produced without causing breakage during the drawing step.

<Example 5: Formation of oxide film by three kinds of metals using sol-gel method>
While stirring a mixed liquid of 3564 g of tetraethoxysilane (same raw material as in Example 1) and 3.00 kg of isopropanol, 305 g of a 0.15 M nitric acid aqueous solution was gradually added and stirred for 3 hours to hydrolyze tetraethoxysilane. .
While stirring the hydrolyzed solution, 724 g of titanium tetra-n-butoxide {Ti (OC ₄ H ₉ ) ₄ , purity: 99.5%, manufactured by Nippon Soda Co., Ltd.} and 292 g of lithium nitrate (LiNO ₃ ) were added to methanol. A solution dissolved in 4.00 kg of (CH ₃ OH) was added and stirred for 2 hours.
This solution was added to a mixed solution of 1373 g of a 0.15 M nitric acid aqueous solution and 11.74 kg of isopropanol under stirring, and further stirred for 3 hours to produce 25 kg of a thin film coating solution. The charged composition of the thin film obtained from this coating solution is Li ₂ O ₅ wt%, TiO ₂ 14 wt%, and SiO ₂ 81 wt%, and the solid content in the coating solution is 5.0 wt%. The coating solution was colorless and transparent.

This coating solution was applied to a glass preform (width 100 mm × length 300 mm × thickness 4.5 mm) produced in the same manner as in Example 1 at a speed of V = 20 cm / min. The obtained thin film was colorless and transparent and homogeneous. The glass preform with a thin film was dried at 120 ° C. for 1 hour, then placed in a heat treatment furnace, heated to 500 ° C. at 200 ° C./hour, and held at 500 ° C. for 1 hour. The thickness of the Li ₂ O ₅ —TiO ₂ —SiO ₂ thin film after the heat treatment heat treatment was 0.15 μm, and the thin film after the heat treatment was also colorless and transparent and homogeneous.
Then, the glass preform formed with the coating of these three kinds of metal oxides is subjected to a drawing process, an outer shape processing / polishing process, and a reduction process in the same manner as in Example 1, and breakage occurs during the drawing process. A polarizing glass was prepared.

<Example 6: Sol - Formation of ZrO ₂ film by Gel Method>
In a mixed solution of 2640 g of ethyl acetoacetate, 1828 g of 2-ethoxyethanol and 7.5 kg of isopropanol under stirring, zirconium tetra-n-propoxide {Zr (OC ₃ H ₇ ) ₄ , purity 74.5%, Nippon Soda Co., Ltd. 4461 g made} was added and allowed to stir for 2 hours.
While this solution was stirred, a mixed solution of 366 g of 0.15 M nitric acid aqueous solution and 8.20 kg of isopropanol was added and stirred overnight to produce 25 kg of a thin film coating solution. The composition of the thin film obtained from this coating solution is ZrO ₂ 100 wt%, and the solid content in the coating solution is 5.0 wt%. The coating solution was light yellow and transparent.

This coating solution was applied to a glass preform (width 100 mm × length 300 mm × thickness 4.5 mm) produced in the same manner as in Example 1 at a speed of V = 11 cm / min using the dipping method. The obtained thin film was colorless and transparent and homogeneous. The glass preform with a thin film was dried at 100 ° C. for 1 hour, then placed in a heat treatment furnace, heated to 500 ° C. at 200 ° C./hour, and held at 500 ° C. for 30 minutes. The thickness of the ZrO ₂ thin film after the heat treatment heat treatment was 0.12 μm and had a metallic luster.
Then, the glass preform was subjected to a drawing step, an outer shape processing / polishing step, and a reduction step in the same manner as in Example 1 to produce a polarizing glass without causing breakage during the drawing step.

<Example 7: Formation of SiO ₂ film with a silicone resin>
A silicone resin (YR3370, manufactured by Momentive Performance Materials Japan GK) was dissolved in a mixed solution of 11.8 kg of isobutyl acetate and 11.8 kg of isopropanol to prepare 25 kg of a thin film coating solution. The composition of the thin film obtained from the coating solution is 100 wt% SiO ₂ , and the solid content in the coating solution is 5.0 wt%. The coating solution was colorless and transparent.

This coating solution was applied to a glass preform (width 100 mm × length 300 mm × thickness 4.5 mm) produced in the same manner as in Example 1 at a speed of V = 30 cm / min by the dipping method. The obtained thin film was colorless and transparent and homogeneous.
This glass preform with a thin film was dried at 100 ° C. for 30 minutes, then placed in a heat treatment furnace, heated to 500 ° C. at 200 ° C./hour, and held at 500 ° C. for 1 hour. The thickness of the SiO ₂ thin film after the heat treatment was 0.22 μm, and this thin film was also colorless and transparent and homogeneous.
Then, the glass preform was subjected to a drawing step, an outer shape processing / polishing step, and a reduction step in the same manner as in Example 1 to produce a polarizing glass without breaking during the drawing step.

<Example 8: Formation of SiO ₂ film by a spin-on glass method>
Spin-on-glass material (OCD T-12 1000V, converted to SiO ₂ ) on the main surface (100 mm × 300 mm surface) of a glass preform (width 100 mm × length 300 mm × thickness 4.5 mm) produced in the same manner as in Example 1. A solid content concentration: 7 wt%, manufactured by Tokyo Ohka Kogyo Co., Ltd.) was applied at a rotational speed of 1500 rpm using a spin coater.
Next, the glass preform coated with the spin-on-glass material is heated at 80 ° C. for 3 minutes in a clean oven, then heated at 150 ° C. for 3 minutes, and further dried at 200 ° C. for 5 minutes. A thin film was formed on the surface.
After this glass preform was cooled to room temperature, a silica-based thin film was formed on the main surface opposite to the above-described surface by the same process as described above.
The thickness of the obtained thin film was 0.23 μm.
Then, the glass preform was subjected to a drawing step, an outer shape processing / polishing step, and a reduction step in the same manner as in Example 1 to produce a polarizing glass without causing breakage during the drawing step.

<Example 9: Formation of SiO ₂ film by LPD method>
384 L of a 2.0 mol / L (liter) hexafluorosilicic acid (H ₂ SiF ₆ , Morita Chemical Co., Ltd.) aqueous solution saturated with SiO ₂ and 0.5 mol / L boric acid (H3BO3, Borax Japan KK) (Manufactured) 16 L was mixed to prepare 400 L of a processing solution.
A glass preform (width 100 mm × length 300 mm × thickness 4.5 mm) produced in the same manner as in Example 1 was immersed in this treatment liquid heated to 35 ° C., and 0.5 mol / L boron was stirred under stirring. The acid aqueous solution was kept for 20 hours while continuously dropping at a rate of 15 mL / min.
The obtained SiO ₂ thin film was colorless and transparent, and the thickness of the thin film was 50 nm.
Then, the glass preform was subjected to a drawing step, an outer shape processing / polishing step, and a reduction step in the same manner as in Example 1 to produce a polarizing glass without causing breakage during the drawing step.

<Example 10: sol to metal particles deposited preform - the formation of SiO ₂ film by Gel Method>
Sodium nitrate and silver nitrate were mixed at a weight ratio of 2: 1 and heated to 450 ° C. to prepare a molten salt. A commercial soda lime glass plate cut into a width of 100 mm, a length of 300 mm and a thickness of 2 mm was immersed in this molten salt for 45 hours, and the sodium ions in the glass and the silver ions in the molten salt were ion-exchanged. Subsequently, this ion-exchanged soda lime glass was heat-treated at 640 ° C. for 9 hours to precipitate approximately 43 μm spherical silver particles.
Thereby, inclusion of silver particles was confirmed over a depth of about 28 μm from both surfaces of the soda lime glass.

Next, a coating liquid was prepared and applied to the glass preform in the same manner as in Example 1, and a thin film having a thickness of 0.19 μm was formed by heat treatment.
This glass preform on which a thin film had been formed was set in a heating furnace 7 (see FIG. 2) and held at 750 ° C. for 30 minutes. Drawing was performed in the same manner as in Example 1 except that the drawing start temperature was set to 700 ° C. and the set tension was set to 12 kg, and drawing was completed without breaking to the end.
The obtained glass sheet had a cross-sectional size of approximately 17 mm width × 0.27 mm thickness, and the drawing tension was 261 kgf / cm ² (25.6 MPa).
The thickness of the Ag particle-containing layer of the glass tape after drawing was about 4 μm from the surface, and the silver particles had an elliptical shape. Thus, it was confirmed that the glass tape was a polarizing glass exhibiting polarization characteristics.
When the obtained tape-shaped glass sheet was cut into a predetermined size and the polarization characteristics were examined, the extinction ratio at a wavelength of 1.55 μm at a distance of 300 mm between the polarizing glass and the detector was 50 dB. In this embodiment, the glass sheet is not polished.

<Comparative Example 1>
Without drawing a metal oxide thin film on the surface of the glass reformer (width 100 mm × length 300 mm × thickness 4.5 mm) produced in the same manner as in Example 1, the drawing was performed under the same conditions as in Example 1. It was. However, since the fracture occurred when the load applied to the lower end of the glass preform reached 14.3 kg (140 kgf / cm ² (13.7 MPa)) in the drawing process, the drawing was terminated here, and the outer shape processing, polishing and reduction were performed. went. The extinction ratio with respect to the stretched glass sheet immediately before the break was 15 dB at a distance of 300 mm between the polarizing glass and the detector and a wavelength of 1.55 μm.

<Comparative Example 2>
Without forming a metal oxide thin film on the surface of the glass reforming (width 100 mm × length 300 mm × thickness 2 mm) in which silver particles produced in the same manner as in Example 10 were dispersed, the same conditions as in Example 10 were used. I did a line drawing. Then, when the set book power was 12 kg and reached 8 kg, the preform was broken and drawing was completed. When the extinction ratio was measured by cutting the stretched glass sheet immediately before breaking to a predetermined size, the extinction ratio at a wavelength of 1.55 μm at a distance of 300 mm between the polarizing glass and the detector was 11 dB.

Tables 1 and 2 show a summary of various conditions in Examples 1 to 10 and Comparative Examples 1 to 2, damages during drawing of the glass preform, characteristics of the produced polarizing glass, and the like. .
The composition (wt%) of the thin film in the table indicates that the organic components (for example, organic functional groups) in the thin film are all oxidized by heat treatment after coating and heating in the drawing process, and the thin film is completely inorganic. It is described as a composition when it becomes.

In Comparative Example 1 and Comparative Example 2 in which the metal oxide thin film was not formed on the glass preform surface, the glass preform was broken in the drawing process.
Moreover, since it broke | broken in the middle of drawing, a copper halide particle or silver particle was not fully expanded, and the extinction ratio of the obtained polarizing glass became 15 dB and 11 dB, respectively, and a thing with a poor polarization function.

On the other hand, in Example 1 in which the SiO ₂ film was formed on the glass preform surface, a glass sheet could be formed without damage in the drawing process, and a polarizing glass having a sufficient polarization function with an extinction ratio of 55 dB was obtained. It was.

Also in Examples 2 to 10, the glass preform was not broken during drawing, and a polarizing glass having a sufficient polarizing function with an extinction ratio of 50 dB to 56 dB could be produced.
Accordingly, and SiO ₂ film containing an organic functional group, SiO ₂ based oxide film containing a plurality of kinds of metal oxides, be a metal oxide thin film containing no SiO _2, to protect the glass preform It was confirmed that it was possible to suppress breakage during drawing.

In particular, in the case of using a glass preform in which metal particles are dispersed on the surface thereof by an ion exchange method as in Example 10, the layer containing drawn metal particles after drawing is usually as thin as several μm. . For this reason, the surface is not ground or polished, and the glass sheet after drawing is used as a polarizing glass with the same thickness.
Therefore, the surface of the produced polarizing glass is coated with a very thin metal oxide thin film having a thickness of, for example, 0.1 μm or less, which is heated and stretched by a drawing process. This metal oxide thin film can be composed of, for example, a SiO ₂ film, a B ₂ O ₃ —SiO ₂ based film, a Li ₂ O—TiO ₂ —SiO ₂ based film, or the like. These metal oxide thin films are excellent in chemical durability, and have the advantage of improving the chemical durability of the polarizing glass by coating the polarizing glass with these films.

  As described above, according to the present invention, by forming the metal oxide thin film on the surface of the glass preform by the liquid phase film forming method, it is possible to surely prevent the glass preform from being broken at the time of drawing. Further, since the film is formed by a simple process such as coating of the coating liquid or immersion in the processing liquid, it is possible to manufacture at a short time and at a low cost.

Moreover, since it is a liquid phase film-forming method, the coating liquid or the processing liquid easily penetrates into the scratches on the surface of the glass preform when the coating liquid is applied or immersed in the processing liquid.
In the method described in Patent Document 3, the surface glass formed on the surface of the core glass is melted in a furnace at the time of stretching to fill the scratches on the surface of the core glass. For this reason, it is described that the viscosity of the surface glass is low.
On the other hand, when two different glasses are melted and joined, if there is a difference in thermal expansion coefficient between the two, the glass may break or cracks may occur. For this reason, it is generally considered that the difference in the value of the thermal expansion coefficient between the two glasses needs to be within 15 × 10 ⁻⁷ / K.
However, the surface glass having a lower viscosity than the core glass as in Patent Document 3 tends to have a larger coefficient of thermal expansion than the core glass, and there is a difference in the value of the coefficient of thermal expansion between the core glass and the surface glass. Easy to grow.
Therefore, it is difficult to produce a polarizing glass in which the thermal expansion coefficients of the core glass and the surface glass are matched, requiring, for example, a very careful operation such as material selection.

  On the other hand, in the method according to the present invention, since it is applied to the surface of the glass preform at the stage of the coating liquid or treatment liquid, it can be easily penetrated into the scratches on the surface of the glass preform from the beginning, and the formed metal Not restricted by the viscosity of the oxide thin film. Therefore, it is possible to protect the glass preform more reliably, and it is not necessary to select a material due to restrictions on the viscosity and the thermal expansion coefficient. Therefore, it is possible to manufacture at a low cost.

  Further, in the liquid phase film forming method such as the sol-gel method, LPD method, and spin-on-glass method exemplified in the present invention, hydrofluoric acid is not used, so that improvement of worker safety and reduction of environmental load are achieved at the same time. Is done.

  The embodiments and examples relating to the method for manufacturing a polarizing lens according to the present invention have been described above. The present invention is not limited to the above-described embodiment, and includes various conceivable forms without departing from the gist of the present invention described in the claims.

DESCRIPTION OF SYMBOLS 1,4 ... Glass preform, 2 ... Scratch, 3 ... Metal oxide thin film, 5 ... Feeding device, 6 ... Fixing jig, 7 ... Heating furnace, 8 ...・ Tensing device, 9 ... glass sheet, 10 ... lid, 11 ... heat generating part, 12 ... insertion hole, 13 ... discharge hole

Claims (6)

Forming a metal oxide thin film on the surface of a glass preform in which metal halide particles or metal particles are dispersed by a liquid phase film forming method;
Drawing the glass preform on which the metal oxide thin film is formed;
The manufacturing method of polarizing glass containing.   The method for producing a polarizing glass according to claim 1, wherein the metal oxide thin film is formed with a thickness of 10 μm or less. The method for producing a polarizing glass according to claim 2, wherein the metal oxide thin film is formed by any one of a sol-gel method, an LPD method, a spin-on-glass method, and a method of applying a silicone resin.   The method for producing a polarizing glass according to claim 3, wherein the metal oxide thin film is bonded to the surface of the glass preform by a metalloxane bond generated by a condensation reaction.   A step of processing and polishing the outer shape of the glass sheet formed by drawing the glass preform in which the metal halide particles are dispersed, and reducing the metal halide particles after processing and polishing the outer shape of the glass sheet. The manufacturing method of the polarizing glass of Claims 1-4.   The said metal oxide thin film is a manufacturing method of the polarizing glass of Claim 5 removed in the process which processes the external shape and grind | polishes the said glass sheet.

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