JP2005272253A - Glass outflow nozzle, method for producing glass article, and method for producing optical element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a glass outflow nozzle for reducing wetting of glass on the outer peripheral part of a glass outflow port when molten glass is flowed out, and producing a high quality glass article. <P>SOLUTION: In the glass outflow nozzle, the whole tip end part 2 including at least the outflow port 3 is made of gold in the glass outflow nozzle A, B for flowing out the molten glass from the outflow port 3 provided at the tip part, or the whole tip end part 2 including at least the outflow port 3 is made of a gold-platinum alloy containing platinum in an amount of ≤80 wt.% in the glass outflow nozzle A, B for flowing out the molten glass from the outflow port 3 provided at the tip part. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a glass outflow nozzle for forming a glass article made of optical glass by causing molten glass to flow out, a method for producing a glass article made of optical glass by flowing out and forming molten glass, and the glass article The present invention relates to a method for producing an optical element by press molding.

As digital still cameras, digital video cameras, camera-equipped cell phones, etc. become smaller, with higher pixels and higher performance, lenses made of high refractive high dispersion glass, high refractive low dispersion glass, and low refractive ultra-low dispersion glass are optical. Necessary for the system. In addition, since the lens can be made aspherical, the optical system can be further miniaturized, and thus an aspherical lens having these optical characteristics is desired.
On the other hand, as a manufacturing method of aspherical glass lenses, a method of precision press molding of a glass preform as a raw material is the mainstream. For this reason, a technology for hot forming a preform from the above glass or a precision press of a preform. It is necessary to develop the technology to do this.

However, optical glasses having the above-described refractive index and dispersion characteristics have been known for some time. However, when hot forming as disclosed in Patent Document 1 is difficult to perform preform molding or precision pressing is difficult There are very many. In particular, high refractive high dispersion glass and low refractive ultra-low dispersion glass are mostly composed of P ₂ 0 ₅ in the composition, and therefore it is difficult to stably form a precision press preform hot. . The reason will be described below.
When these glasses are melted, they are extremely wettable with platinum and platinum alloy materials (for example, platinum 95 wt% -gold 5 wt% alloy, etc.) used for the glass outlet, so the outer periphery of the glass outlet is within a short time. It will be covered with molten glass. Since the glass adhering to the outer periphery of the outlet stays at the outlet, alteration such as crystallization occurs with time. And if there is a modified glass on the outer periphery of the tip of the outlet, the modified glass is mixed into the outflowing molten glass surface or inside, causing problems such as streaky dark surface striae on the hot-formed preform surface. .
JP-A-2-14839

The present invention has been made in order to solve the above problems, and is a glass for producing a high-quality glass article by reducing glass wetting to the outer peripheral portion of the glass outlet when the molten glass flows out. It is a first object to provide an outflow nozzle.
The present invention also provides a method for producing a glass article capable of reducing and preventing the deterioration in quality due to the above-mentioned wetting when the molten glass flows out from the nozzle, and uses the glass article produced by the method. It is a second object of the present invention to provide a method for manufacturing an optical element that can manufacture a high-quality optical element with high productivity.

The present invention has been made to solve the above problems,
(1) In a glass outflow nozzle that allows molten glass to flow out from an outlet provided at the tip,
A glass outflow nozzle characterized in that the entire tip including at least the outflow port is made of gold,
(2) In a glass outflow nozzle that allows molten glass to flow out from an outlet provided at the tip,
A glass outflow nozzle characterized in that the entire tip including at least the outlet is made of a gold / platinum alloy having a platinum content of 80 wt% or less,
(3) The glass outflow nozzle according to (1) or (2), wherein the entire nozzle is made of the same kind of material,
(4) A conduit portion provided with a flow path of molten glass inside and a tip portion that can be attached to the conduit portion, and melted from the conduit portion to the outlet of the tip portion with the tip portion attached to the conduit portion The glass outflow nozzle according to any one of the above (1) to (3), having a structure in which a flow path for flowing glass is formed,
(5) In the method for producing a glass article, the molten glass is caused to flow out of the nozzle, and a glass article made of optical glass is formed.
As the nozzle, the glass outflow nozzle according to any one of the above (1) to (4) is used, a method for producing a glass article,
(6) The glass article according to (5) above, wherein molten glass is caused to flow out of the nozzle, and glass having a constant weight is separated one after another to produce a precision press-molding preform made of optical glass as the glass article. Production method,
(7) The molten glass is allowed to flow out of the nozzle, continuously cast into a mold and molded into a glass plate, and the glass plate molded from the mold is continuously drawn out to produce a plate-shaped optical glass as a glass article. The method for producing a glass article according to (5) above,
(8) The molten glass is caused to flow out of the nozzle to produce a glass molded body made of optical glass, and the molded body is machined to produce a press molding preform made of optical glass as a glass article. (5) The method for producing a glass article according to
(9) The method for producing a glass article according to any one of (5) to (8), wherein the optical glass is a phosphate glass or a fluorophosphate glass.
(10) A method for producing an optical element, characterized in that an optical element is produced by heating a precision press-molding preform obtained by the method described in (6) above and precision-molding it.
(11) An optical element manufacturing method, wherein an optical element is manufactured through a step of press-molding a press-molding preform obtained by the method described in (8) above,
(12) A method for producing an optical element, characterized in that a plate-like optical glass obtained by the method described in (7) above is machined to produce an optical element, and (13) a phosphate glass or a fluoride glass. The method for producing an optical element according to any one of (10) to (12), wherein an optical element made of a phosphate glass is produced.
Is a summary.

ADVANTAGE OF THE INVENTION According to this invention, when letting a molten glass flow out, the glass wetting out to the outer peripheral part of a glass outflow port can be reduced, and the glass outflow nozzle for producing a high quality glass article can be provided.
Moreover, according to this invention, when letting a molten glass flow out from the said nozzle, the manufacturing method of the glass article which can reduce and prevent the quality fall by said wetting up can be provided.
Furthermore, the manufacturing method of the optical element which can manufacture a high quality optical element on the basis of high productivity using the glass article produced by the said method can be provided.

Hereinafter, the best mode for carrying out the invention will be described in the order of a glass outflow nozzle, a glass article manufacturing method, and an optical element manufacturing method.
I. Glass Outflow Nozzle The glass outflow nozzle of the present invention has a first aspect (referred to as nozzle A) and a second aspect (referred to as nozzle B).
The nozzle A is a glass outflow nozzle through which molten glass flows out from an outlet provided at the tip, and at least the entire tip including the outlet is made of gold.
Nozzle B is a glass outflow nozzle through which molten glass flows out from an outlet provided at the tip, and at least the entire tip including the outlet is made of a gold / platinum alloy with a platinum content of 80% by weight or less. It is characterized by.
The reason why the gold / platinum alloy having a gold and platinum content of 80% by weight or less is selected as the material of the tip in the nozzle A and the nozzle B will be described in detail below.

The inventors of the present invention horizontally placed five flat plates having a mirror-finished surface, placed a TiO ₂ -containing phosphate glass lump on each flat plate, heated and melted in the air, then cooled and cooled each flat plate. The spread of the upper glass was observed from above. The flat plates used were pure gold (Au), gold 80 wt% -platinum 20 wt% alloy (80 Au-20 Pt alloy), platinum 85 wt% -rhodium 10 wt% -gold 5 wt% alloy (85 Pt-10Rh-5Au alloy). Further, platinum 95 wt% -gold 5 wt% alloy (95Pt-5Au alloy) and gold 80 wt% -palladium 20 wt% alloy (80Au-20Pd alloy).

As a result, when the flat plate is made of a conventional nozzle material such as 95Pt-5Au alloy or 80Au-20Pd alloy, the glass spreads flat and the contact angle with the flat plate is as small as 10 ° or less, whereas the flat plate is Au or 80Au-20Pt. When it was made of an alloy, it was found that the glass spread was small and the contact angle was as large as 30 ° or more.
And as a material of the tip part including the nozzle outlet, when the nozzle is made using the conventional 95Pt-5Au alloy and the glass flows out, wetting up occurs, but the tip part including the nozzle outlet It has been found that it is preferable to produce nozzles using Au and 80Au-20Pt alloys as materials and to let the glass flow out without wetting up.

A gold / platinum alloy in which the mixing ratio of gold and platinum was changed and a similar experiment was attempted. As shown in FIG. 1, as the platinum content increased, the contact angle decreased and the platinum content was 80 wt. When the ratio exceeds 50%, the contact angle is remarkably reduced as in the case of 95Pt-5Au alloy which is a conventional nozzle material. Therefore, in the nozzle B, the platinum content is limited to 80% by weight or less, preferably 60% by weight or less, more preferably 30% by weight or less. The contact angle shown in FIG. 1 was measured after using a TiO ₂ -containing phosphate glass (outflow temperature: 910 ° C.), heating the glass to 910 ° C. in the atmosphere, and cooling it. As described above, when the platinum content in the gold / platinum alloy is 80% by weight or less, a contact angle of 30 ° or more, which is a measure of the effect of reducing wetting, can be obtained.
On the other hand, when a precious metal other than platinum is alloyed with gold, it has been found that the same effect as that of a gold / platinum alloy having a platinum content of 80 wt% or less used in the nozzle B of the present invention cannot be obtained. For example, a gold / palladium alloy, which is a typical gold alloy, has a very small contact angle even if the gold content is 80%.

FIG. 2 shows the heating of TiO ₂ -containing phosphate glass on a flat plate made of various materials such as Au (pure gold), 80Au-20Pt alloy, 80Au-20Pd alloy, 60Au-40Pd alloy, 95Pt-5Au alloy, 85Pt-10Rh-5Au alloy. The relationship between the temperature and the contact angle is shown, but when the heating temperature is around 700 ° C., there is no great difference in the contact angle between the six types of flat plates, but when heated to 900 ° C., which is close to the glass outflow temperature, Is Au, 80Au-20Pt alloy, the contact angle exceeds 50 ° and wetting can be effectively prevented, but the flat plate is 80Au-20Pd alloy, 60Au-40Pd alloy, 95Pt-5Au alloy, 85Pt-10Rh. In the case of -5Au alloy, the contact angle is 20 ° or less. If the contact angle is so small, the wetting of the glass is reduced. It is difficult with.
Determination of the platinum content (or gold content) in the gold / platinum alloy may be determined so that the contact angle of the glass that is about to flow out at the outflow temperature is 30 ° or more. From this point of view, a platinum-containing gold / platinum alloy having a contact angle of 40 ° or more is preferable, and a platinum-containing gold / platinum alloy having a contact angle of 44 ° or more is more preferable.

  Considering the material of the nozzle from the viewpoint of heat resistance, the melting point of gold is 1063 ° C., so that it can be used sufficiently for the outflow of phosphate glass or fluorophosphate glass that flows out at 700 to 1000 ° C. However, in view of practical use, it is preferable that the melting point is as high as possible. To raise the melting point, it is preferable to alloy with a noble metal having a high melting point. However, as described above, the alloying partner is limited to platinum. The melting point of the gold / platinum alloy can be increased to 1190-1230 ° C. with a platinum content of 20-30 wt%, for example. If the melting point is about 1200 ° C., it can be used practically without any problem. As is clear from the Pt—Au alloy phase diagram shown in FIG. 3, there is an immiscible region in this alloy system. For example, at 1000 ° C., phase separation occurs in a region of 30 to 85% platinum. Therefore, in order to obtain an alloy having this composition range, it is necessary to rapidly cool the alloy from a high temperature state where a uniform melt is formed, and form an alloy. Since rapid cooling is required in this way, the platinum content is preferably 30% by weight or less from the viewpoint of manufacturing a gold / platinum alloy.

  On the other hand, a method of coating the outer peripheral surface of a conventional 95Pt-5Au alloy nozzle with gold is also conceivable, but is not preferable for the following reasons. Gold coated on the surface of the platinum alloy is exposed to a high temperature when the glass flows out, so that the gold coat diffuses into the alloy, and the gold color is lost and the effect of preventing wetting is lost. Actually, when a nozzle coated with gold by sputtering was used to flow out in the atmosphere, the tip of the nozzle became wet with glass one hour after the outflow, and it was not gold after cooling. Therefore, what coated the outer peripheral surface with the material different from nozzle material cannot endure use for a long time.

  On the other hand, according to the nozzles A and B of the present invention, the entire outer end portion is made of gold, gold / platinum alloy (however, the platinum content is 80 wt% or less). Since it can be kept in a state where it is difficult to wet for a long time, a high-quality glass article can be stably formed. In addition, in this invention, a front-end | tip part means the site | part containing the nozzle outer peripheral surface where the outflow port of a molten glass and the outflow glass may wet up.

  As shown in FIG. 4, the nozzles A and B of the present invention may be integrally formed by a conduit 1 in which a flow path of molten glass is provided, and as shown in FIG. And a distal end portion 5 that can be attached to the conduit portion 4, and the distal end portion 5 is attached to the conduit portion 4 with a screw 6 to the outlet 7 of the distal end portion 5. You may have a structure in which the flow path which flows a molten glass without a leak is formed.

  As a specific example, the surface of the conduit portion where the glass flow path outlet is formed and the surface of the tip portion where the glass flow path inlet is formed are in close contact with each other so that the outlet and the inlet are connected to each other with screws. Attach by means of. If the above contact is not properly made, molten glass will enter between the conduit part and the tip part and the glass will leak out from the nozzle, so it is necessary to attach both members so that the glass does not leak at least There is.

Moreover, in the case of the structure provided with the said conduit | pipe part and a front-end | tip part, a conduit | pipe part and a front-end | tip part may be made from the same material, and may be made from a different material. Alternatively, the pipe portion may be press-fitted into the cylindrical tip portion so as to have an integral structure. At that time, the press-fitting conditions are determined so that the conduit portion and the tip portion are kept in close contact with each other even at the upper limit of the nozzle operating temperature.
The nozzle may be integrated with a pipe that guides the glass from the melting container to the nozzle, or may be provided with a desorption function between the pipe and the nozzle and used by being attached to the pipe.
When integrating with the pipe, considering the versatility of the outflow equipment, the conduit part is made of platinum or platinum alloy with the same melting point as the pipe, and the tip part is gold, gold or platinum alloy (however, the platinum content is 80% by weight or less) is preferable. Examples of the mounting function for mounting the distal end portion to the conduit portion include screwing.

As explained above, if the platinum content in the gold / platinum alloy system is less than a certain value, the wetting-up suppressing effect can be obtained, but the heat resistance of the nozzle tip is reduced accordingly.
Since the operating temperature range of the nozzle is determined by the glass to be molded, even if the glass has a low molding temperature even if the nozzle has a low heat resistance, the decrease in the heat resistance is not a problem. The heat resistance is lower than that, but it has sufficient practicality.
The glass and the glass molding temperature at which the quality deterioration due to wetting is remarkable will be described later.

II. Method for producing a glass article manufacturing process then the invention of the glass article will be described.
The method for producing a glass article of the present invention is a method for producing a glass article in which molten glass is caused to flow out of a nozzle and a glass article made of optical glass is formed, and the nozzle A or nozzle B of the present invention is used as the nozzle. It is characterized by.
Here, the nozzle A is made of gold at the entire tip including at least the outlet, and the nozzle B is made of gold / platinum alloy having a platinum content of 80 wt% or less at the tip including at least the outlet. However, since the details have been sufficiently described above, the description thereof is omitted here.

In the method for producing a glass article of the present invention, a molten glass as a starting material is prepared by a well-known method, homogenized by clarification and stirring, and accumulated in a melting vessel. A pipe for guiding the internal molten glass to the nozzle is connected to the bottom of the platinum melting vessel, and the molten glass reaches the nozzle through the pipe.
The temperature of the melting container, pipe, and nozzle is controlled in order to keep the temperature of the internal glass appropriately, and a constant flow rate of molten glass flows out from the nozzle outlet.

The first aspect of the method for producing a glass article of the present invention is to produce a precision press-molding preform made of optical glass as a glass article by causing molten glass to flow out of a nozzle and separating glass of a constant weight one after another. Is the method.
In the first aspect, the molten glass flowing out at a constant flow rate is separated at a constant cycle calculated based on the preset weight of the preform and the flow rate.

  As a method for separating glass having a constant weight, a method of dropping molten glass from a nozzle and separating it as a glass drop of the weight (referred to as a dropping method), a tip of a molten glass flow flowing out from the nozzle is a support or molding. A method in which a neck is formed between the nozzle side and the tip of the glass flow, and then the support or the mold is rapidly lowered to separate the molten glass lump on the tip side from the neck (falling cutting method) Etc.). In addition, when glass flows out, gas flows along the outer periphery of the nozzle and in the glass outflow direction (vertically below), and a downward wind pressure is applied to the glass at the tip of the nozzle to further reduce the wetting of the glass to the outer periphery of the nozzle. You can also.

  The method of flowing gas along the outer periphery of the nozzle is also effective in reducing the weight of the molten glass droplet obtained by the dropping method. In the dropping method, dripping occurs when the balance between the gravity acting on the glass and the surface tension at which the glass stays at the tip of the nozzle is lost and the gravity increases. By constantly flowing a gas at a constant flow rate along the pipe periphery as described above, the downward force applied to the glass is increased, so that it is possible to drop a glass drop having a smaller weight than when no gas is flowed. it can. In addition, it is preferable to flow gas so that it may become a laminar flow in the vicinity of a nozzle tip over a nozzle periphery.

The separated molten glass lump is molded into a preform having a predetermined shape on a mold. On the mold, a method of forming glass while applying a wind pressure to float (referred to as a floating molding method) is desirable.
For example, using a molding die provided with a recess provided with a port for jetting the gas for applying the wind pressure (called floating gas) to the bottom, a molten glass lump is supplied to the recess and the glass is moved up and down in the recess. The spherical preform can be formed by rotating and rotating, and the recess or recess provided with a large number of gas ejection ports is made of a porous body, and the floating gas is ejected from the entire inner surface of the recess to float the glass. And a preform can also be shape | molded in the shape along the shape of a recessed part.
After the glass is formed into a preform on a mold, the glass is taken out of the mold after cooling to a glass transition temperature or a temperature lower than the above temperature.

Optical elements produced by precision press molding of preforms are predominantly in the shape of a single rotationally symmetric axis, such as a lens. A shape provided (for example, a spheroid, a shape obtained by extending a sphere in a certain axial direction, a crushed shape, or the like) is desired. In order to produce a preform having such a shape, a glass lump having a shape similar to the target preform shape may be formed.
In addition, precision press molding preforms are required to have high weight accuracy. However, if the glass wets significantly around the nozzle periphery, the molten glass lump that separates from the nozzle when the preform is molded by, for example, the dropping method. The weight varies. According to the present invention, since wetting of the glass to the outer periphery of the nozzle can be reduced, a preform with high weight accuracy can be produced even with glass that easily wets.
According to the present invention, it is possible to produce a precision press-molding preform having a weight tolerance within ± 2%, preferably within ± 1% based on the target weight.

According to a second aspect of the method for producing a glass article of the present invention, molten glass is allowed to flow out of a nozzle, continuously cast into a mold and molded into a glass plate, and the glass plate molded from the mold is continuously drawn out. And a plate-like optical glass as a glass article. The glass plate has a certain width by being regulated by the mold, and has a certain thickness by keeping the liquid level of the molten glass in the mold constant. This glass plate is annealed and then divided into glass pieces called cut pieces. Finally, the surface is ground or polished to form a press-molding preform or a spherical lens. According to the second aspect, since the risk that glass that has deteriorated due to wetting to the outer periphery of the nozzle is mixed into the glass plate is reduced, the yield of press-molding preforms and optical elements produced from cut pieces is improved. be able to.
By smooth finishing the glass surface by the above polishing process, the preform can be used for precision press molding applications. By roughing such as barrel polishing, reheating in the atmosphere, pressing It can also be used in a method of forming an optical element by forming a molded product having an approximate shape of the optical element by performing molding and grinding and polishing the molded article.
Further, the glass plate produced according to the second aspect can be sliced into a thin plate shape as described later, and the opposing main surface can be polished to produce a plate-like optical element.

According to a third aspect of the method for producing a glass article of the present invention, a glass molded body made of optical glass is produced by letting molten glass flow out from a nozzle, and the molded body is machined to be used for press molding as a glass article. A method for manufacturing a preform.
For the production of the glass molded body, the same method as in the first aspect may be used, or the same method as in the second aspect may be used. When producing a glass molded body by the same method as in the first aspect, after annealing the glass molded body to reduce distortion, barrel polishing can be performed to produce a preform for press molding. It is also possible to produce a precision press-molding preform having a smooth surface by polishing the surface of the body.
When producing a glass molded body using the same method as in the second aspect, after annealing the glass molded body to reduce distortion, the molded body is divided into cut pieces by a method such as cutting, and barrel polishing is performed. It is possible to manufacture a preform for press molding, or it is possible to manufacture a preform for precision press molding having a smooth surface by polishing the surface of the glass molded body.
According to the 3rd aspect, since the danger that the glass which changed in quality by the wetting up to the nozzle outer periphery will mix in the inside of a glass forming body is reduced, the yield of the preform for press molding can be improved.

The optical glass used in the method for producing a glass article of the present invention is not particularly limited, but representative examples include phosphate glass, fluorophosphate glass, and rare earth metal oxide-containing borate glass. Of these, phosphate glass and fluorophosphate glass are particularly prominent in wetting, so that the effect of improving the quality of glass articles formed by the application of the present invention is great.
In particular, phosphate glass and / or fluorophosphate glass containing alkali metal oxide and / or B ₂ O ₃ is easily volatilized because alkali metal oxide, B ₂ O ₃ and fluorine are easily volatilized. Since the quality of the glass article tends to deteriorate, it is preferable to apply the present invention to the molding of the various glasses. Moreover, since glass containing ₁₅ to 70 mol% of P ₂ O ₅ tends to be wetted up, it is preferable to apply the present invention to such glass molding.
Further, both nozzles A and B are preferable as nozzles for flowing out the various glasses.

Next, the optical glass preferably used in the method for producing a glass article of the present invention will be described in more detail.
[Glass containing P ₂ O ₅ , Nb ₂ O ₅ and Li ₂ O]
Glass containing P ₂ O ₅ , Nb ₂ O ₅ and Li ₂ O has a refractive index (nd) of 1.7 or more and an Abbe number (νd) of 35 or less (particularly a refractive index (nd) of 1.75 to 2, It is preferable as a glass that realizes an optical constant of a number (νd) 17 to 30). Such glass, by _{mol%, P 2 O 5 15~45%,} Nb 2 O 5 3~35%, Li 2 O 2~35%, TiO 2 0~20%, WO 3 0~40 %, Bi ₂ O ₃ 0-20%, B ₂ O ₃ 0-30%, BaO 0-25%, ZnO 0-25%, MgO 0-20%, CaO 0-20%, SrO 0-20%, Na ₂ O 0-30%, K ₂ O 0-30% (however, the total amount of Li ₂ O, Na ₂ O and K ₂ O is 45% or less), Al ₂ O ₃ 0-15%, SiO ₂ 0 Illustrated glass containing 15%, La ₂ O ₃ 0-10%, Gd ₂ O ₃ 0-10%, Yb ₂ O ₃ 0-10%, ZrO ₂ 0-5%, Ta ₂ O ₅ 0-10% can do.
In the above composition range, P ₂ O ₅ is a formed product of a glass network structure and is an essential component for imparting stability that can be produced to glass. However, if the content of P ₂ O ₅ exceeds 45 mol%, the glass transition temperature and yield point tend to increase, and the weather resistance tends to deteriorate. Further, if it is less than 15 mol%, the glass tends to be devitrified and the glass becomes unstable, so the content of P ₂ O ₅ is preferably in the range of 15 to 45%, and in the range of 17 to 40 mol%. Is more preferable.

Nb ₂ O ₅ is an indispensable component for imparting characteristics such as high refractive index and high dispersion as described above. However, if its content exceeds 35%, the glass transition temperature and yield point increase, the stability deteriorates, the high-temperature solubility also deteriorates, and there is a tendency that foaming and coloring tend to occur during precision press molding. On the other hand, when the content is 3% or less, the durability of the glass deteriorates and it is difficult to obtain a required high refractive index. Therefore, the content is preferably in the range of 3 to 35%. It is more preferable to set it in a range of ˜30%.

Li ₂ O is the most effective component for lowering the glass transition temperature as described above. Compared with other alkalis, Li ₂ O hardly reduces the refractive index and does not deteriorate the durability. However, its content is difficult reduction in transition temperature is less than 2%, when it exceeds 35%, stability of the glass is significantly deteriorated, since the deteriorated durability, the content of Li 2 _O 2 to 35% It is preferable to be in the range. More preferably, it is 5 to 30% of range.

TiO ₂ has the effect of imparting high refractive index and high dispersibility and improving devitrification stability. However, if the content exceeds 20%, the devitrification stability and transmittance of the glass are rapidly deteriorated, the yield point and the liquidus temperature are also rapidly increased, and the glass is easily colored during precision press molding. Therefore, the content is preferably 0 to 20%, and more preferably 0 to 15%.

WO ₃ is an effective component for imparting high refractive index, high dispersion characteristics and low-temperature softening properties. WO ₃ functions to lower the glass transition temperature and the yield point and to increase the refractive index in the same manner as the alkali metal oxide. And since there exists an effect which suppresses the wettability of glass and a press-molding die, there exists an effect that the mold release property of glass becomes very good in the case of precision press molding. However, when WO ₃ is excessively introduced, for example, exceeding 40%, the glass tends to be colored, while the high-temperature viscosity of the glass also decreases, so that hot forming tends to be difficult. Therefore, the content is preferably 0 to 40%, and more preferably 0 to 35%.

Bi ₂ O ₃ is a component that imparts high refractive index and high dispersibility, is a component that has the effect of greatly expanding and stabilizing the glass generation region, and is a component that increases the weather resistance of glass. . Therefore, by introducing Bi ₂ O ₃ , it is possible to vitrify even a glass having a low content of P ₂ O ₅ . Further, by introducing Bi ₂ O ₃ , the wetting angle when the molten glass is placed on a platinum plate can be increased. The increase in the wetting angle makes it difficult for the glass to get wet on the outer periphery of the outflow pipe. Therefore, it is also effective in reducing the surface striae of the preform. Moreover, the weight accuracy of a glass lump can also be improved by reducing wetting. However, if the content exceeds 20%, the glass tends to be devitrified and colored at the same time, so the content of Bi ₂ O ₃ is preferably 0 to 20%. More preferably, it is 15%. Incidentally, in order to obtain the effect by the introduction of _Bi 2 _{O 3,} in the above range, the content of _Bi 2 _{O 3} is preferably from 0.2% or more, more that 0.5% or more preferable.

B ₂ O ₃ is an effective component for improving the glass meltability and homogenizing the glass, and at the same time, by introducing a small amount, it changes the bondability of OH inside the glass, and foams the glass during precision press molding. The effect of suppressing is acquired. However, if more than 30% of B ₂ O ₃ is introduced, the weather resistance of the glass deteriorates or the glass becomes unstable, so the content is preferably in the range of 0 to 30%. A more preferred range is from 0 to 25%.

BaO is a component having an effect of imparting a high refractive index, improving devitrification stability, and lowering the liquidus temperature. When WO ₃ is introduced, particularly when a large amount of WO ₃ is introduced, the introduction of BaO has a great effect of suppressing coloration of the glass and enhances devitrification stability. When the content of P ₂ O ₅ is small, the weather resistance of the glass There is also an effect of improving the nature. However, if the content of BaO exceeds 25%, not only the glass becomes unstable, but also the transition temperature and the yield point increase, so the content of BaO is preferably 0 to 25%. More preferably 20%.

ZnO is a component that can be introduced to increase the refractive index and dispersion of the glass. The introduction of a small amount of ZnO also has the effect of lowering the glass transition temperature, yield point, and liquidus temperature. However, when introduced excessively, the devitrification stability of the glass is remarkably deteriorated, and the liquidus temperature may be increased. Therefore, the ZnO content is preferably 0 to 25%, more preferably 0 to 20%, and still more preferably 0 to 15%.
MgO, CaO, and SrO are components introduced to adjust the stability and weather resistance of the glass. However, if too much is introduced, the glass becomes very unstable, so the content ranges from 0 to 20%. Preferably, it is 0 to 15%.

Na ₂ O and K ₂ O are components that can be introduced to improve the devitrification resistance of the glass, to lower the glass transition temperature, the yield point, and the liquidus temperature, and to improve the meltability of the glass. is there. However, if any of Na ₂ O and K ₂ O is more than 30%, or if the total amount of Li ₂ O, Na ₂ O and K ₂ O is more than 45%, the stability of the glass is deteriorated. In addition, since the weather resistance and durability of the glass may be deteriorated, the contents of Na ₂ O and K ₂ O are preferably 0 to 30%, respectively, and Li ₂ O, Na ₂ O and K ₂ The total amount of O is preferably 0 to 45%. More preferably, Na ₂ O is 0 to 20%, K ₂ O is 0 to 25%, and Na ₂ O is further preferably 0 to 5% by weight.

Al ₂ O ₃ , SiO ₂ , La ₂ O ₃ , Gd ₂ O ₃ , Yb ₂ O ₃ , ZrO ₂ , and Ta ₂ O ₅ are components that can be introduced when adjusting the stability and optical constant of glass. is there. However, all of these components increase the glass transition temperature and may reduce precision press formability. Therefore, the content is less than 15% for Al ₂ O ₃ and SiO ₂ , and 0 to 10% for La ₂ O ₃ , Gd ₂ O ₃ , Yb ₂ O ₃ , ZrO ₂ , and Ta ₂ O ₅ , respectively. it is desirable to keep _{the, Al 2 O 3, SiO 2} 0~12% respectively _{for, La 2 O 3, Gd 2} O 3, Yb 2 O 3, ZrO 2, Ta 2 O 5 , respectively 0-8% for More preferably.

Sb ₂ O ₃ is effective as a glass refining agent, but if added over 1%, the glass tends to foam during precision press molding, so the content is made 0 to 1%. Further, other components such as TeO ₂ and Cs ₂ O can be introduced up to a total of 5% as long as the object of the present invention is not impaired.
However, since TeO ₂ is toxic, it is desirable not to use it from the viewpoint of environmental influences. Similarly, it is also desirable not to use compounds such as PbO, As ₂ O ₂ , CdO, Tl ₂ O, radioactive substances, Cr, and Hg. . Further, it is preferable not to introduce because Ag 2 _O is also a special, not necessary.

[P ₂ O ₅ and BaO-containing glass]
A glass containing P ₂ O ₅ and BaO is preferable as a glass that realizes an optical constant having an Abbe number (νd) of 55 or more (particularly an Abbe number (νd) of 55 to 80).
As the glass, by _{mol%, P 2 O 5 20~65%,} BaO 1~50%, Li 2 O 0~30%, Na 2 O 0~20%, K 2 O 0~15%, ZnO _{0~20%, B 2 O 3 0~25} %, Al 2 O 3 0~10%, Gd 2 O 3 0~10%, 0~20% MgO, CaO 0~20%, SrO 0~20%, Examples thereof include glass containing Bi ₂ O ₃ 0 to 10% and Sb ₂ O ₃ 0 to 1%.

[P ₂ O ₅ and ZnO-containing glass]
A glass containing P ₂ O ₅ and BaO is also preferable as a glass that realizes an optical constant having an Abbe number (νd) of 55 or more (particularly an Abbe number (νd) of 55 to 80).
As the glass, by _{mol%, P 2 O 5 20~65%,} 0.1~20% ZnO, Li 2 O 0~30%, Na 2 O 0~20%, K 2 O 0~15% , B ₂ O ₃ 0-25%, Al ₂ O ₃ 0-10%, Gd ₂ O ₃ 0-10%, MgO 0-20%, CaO 0-20%, SrO 0-20%, BaO 0-50 %, Bi ₂ O ₃ 0 to 10%, and Sb ₂ O ₃ 0 to 1%.

[P ₂ O ₅ , BaO and ZnO-containing glass]
A glass containing P ₂ O ₅ , BaO and ZnO is also preferable as a glass that realizes an optical constant having an Abbe number (νd) of 55 or more (particularly an Abbe number (νd) of 55 to 80).
As the glass, by _{mol%, P 2 O 5 20~65%,} BaO 1~50%, 0.1~20% ZnO, Li 2 O 0~30%, Na 2 O 0~20%, K _{2 O 0~15%, B 2 O} 3 0~25%, Al 2 O 3 0~10%, Gd 2 O 3 0~10%, 0~20% MgO, CaO 0~20%, SrO 0~20 %, Bi ₂ O ₃ 0 to 10%, and Sb ₂ O ₃ 0 to 1%.

In P ₂ O ₅ and BaO-containing glass, P ₂ O ₅ and ZnO-containing glass, P ₂ O ₅ , BaO and ZnO-containing glass, P ₂ O ₅ is a product of a glass network structure. If the stability of the glass decreases and exceeds 65%, the transition temperature and yield point of the glass increase and the weather resistance tends to deteriorate.

BaO has a function of increasing the refractive index and improving devitrification resistance and weather resistance, but excessive introduction increases the glass transition temperature and the yield point, and also decreases the stability of the glass.
ZnO functions to lower the glass transition temperature and the yield point and improve the stability of the glass, but the dispersion increases due to excessive introduction.

Li ₂ O lowers the glass transition temperature and the yield point, but the weather resistance and the stability of the glass are lowered due to excessive introduction, and the refractive index is also lowered.
Na ₂ O, K ₂ O works to improve low-temperature softening property, devitrification resistance, glass melting property, and stability, but excessive introduction reduces the stability of the glass and deteriorates the weather resistance. End up.
B ₂ O ₃ functions to improve the meltability and homogeneity of the glass, and also functions to prevent the glass from foaming during precision press molding by changing the bonding properties of the hydroxyl groups in the glass. However, when introduced excessively, the weather resistance deteriorates and the stability of the glass also decreases.

Al ₂ O ₃ functions to improve the weather resistance, but the glass transition temperature and the yield point increase due to excessive introduction, and the stability and meltability of the glass deteriorate. Also, the refractive index is lowered.
Gd ₂ O ₃ functions to increase the refractive index and improve the stability of the glass. However, excessive introduction increases the dispersion or decreases the stability of the glass.
MgO functions to increase weather resistance and stability and improve low-temperature softening properties, but glass stability decreases due to excessive introduction.

CaO and SrO improve the stability of the glass, but the excessive introduction reduces the durability of the glass and the refractive index.
Bi ₂ O ₃ is an optional component that increases the refractive index and improves the stability of the glass.
Sb ₂ O ₃ can be added as a fining agent. Excessive addition facilitates foaming of the glass during precision press molding.

  The above glass is an example of a phosphoric acid-containing glass, but these glasses are very useful as precision press-molding glasses, but are also glasses that are difficult to form a good quality preform due to wetting. However, by applying the method of the present invention to such a glass, it is possible to manufacture a preform with high productivity, and thus manufacturing a high-quality optical element with high productivity. can do.

[Fluorophosphate glass]
Fluorophosphate glass has a relatively low glass transition temperature and is suitable for precision press molding. From the viewpoint of precision press moldability and hot formability, and from the viewpoint of imparting low dispersion characteristics with an Abbe number (νd) of 65 or more, a preferred fluorophosphate glass has Al, Ca and Sr as cation components and anion components. A particularly preferred fluorophosphate glass (hereinafter referred to as “glass A”) contains F and O as essential components. Al (PO ₃ ) _{30 to} 20%, Ba (PO ₃ ) _{2 in} terms of mol%. 0-30%, Mg (PO ₃ ) ₂ 0-30%, Ca (PO ₃ ) ₂ 0-30%, Sr (PO ₃ ) ₂ 0-30%, Zn (PO ₃ ) ₂ 0-30%, NaPO ₃ 0-15%, AlF ₃ 2-45%, ZrF ₄ 0-10%, YF ₃ 0-15%, YbF ₃ 0-15%, GdF ₃ 0-15%, BiF ₃ 0-15%, LaF _{3 0~10%,} MgF 2 0~2 _{%, CaF 2 2~45%, SrF} 2 2~45%, BaF 2 0~20, ZnF 2 0~30%, LiF 0~10%, 0~15% NaF, KF 0~15%, Li 2 O _{0~5%, Na 2 O 0~5%} , K 2 O 0~5%, 0~5% MgO, CaO 0~5%, SrO 0~5%, BaO 0~5%, ZnO 0~5% Is included.
The composition range will be described in detail. The content of each component is expressed in mol% unless otherwise specified.

Al (PO ₃ ) ₃ is a component constituting the glass network structure and is the most important component for improving the weather resistance of the glass. However, if its content exceeds 20%, the thermal stability of the glass decreases. The liquid phase temperature and the optical properties (dispersion is increased) may be greatly deteriorated, so the content is preferably limited to 20% or less. More preferably, it is 0.5 to 15% of range.

Ba (PO ₃ ) ₂ , Mg (PO ₃ ) ₂ , Ca (PO ₃ ) ₂ , and Sr (PO ₃ ) ₂ are components that constitute the glass network structure, similar to Al (PO ₃ ) ₃ , It is an important component that improves the weather resistance of glass. If the content exceeds 30%, the dispersion of the glass is increased, and the weather resistance is also deteriorated due to an increase in P ₂ O ₅ . Therefore, each content is preferably 30% or less. A more preferable content of each component of Ba (PO ₃ ) ₂ , Mg (PO ₃ ) ₂ , Ca (PO ₃ ) ₂ , and Sr (PO ₃ ) ₂ is in the range of 0 to 25%. In order to obtain a desired optical constant, the total amount of the above components (Mg (PO ₃ ) ₂ + Ca (PO ₃ ) ₂ + Sr (PO ₃ ) ₂ + Ba (PO ₃ ) ₂ ) should be 35% or less. Is preferable, and it is more preferable to set it as 32% or less.
Zn (PO ₃ ) ₂ is a component that improves the stability of the glass, but when introduced in excess of 30%, the dispersion of the glass increases and the durability deteriorates, so the content is made 0-30%. It is preferable to do.

NaPO ₃ is a component that improves the stability of the glass, but if it is introduced in an amount exceeding 15%, the durability deteriorates, so the content is preferably 0 to 15%.
AlF ₃ is a component that improves the stability of the glass and lowers the dispersion, but if its content is more than 45%, the stability of the glass is remarkably lowered and the solubility is also deteriorated. On the other hand, if it is less than 2%, the target optical properties cannot be obtained, so the content is preferably in the range of 2 to 45%, more preferably in the range of 4 to 40%.
ZrF ₄ is a glass network-forming component, and is a component that improves stability and durability. However, it becomes difficult to obtain desired optical characteristics by excessive introduction, and the stability is also lowered. % Is preferable.

YF ₃ , YbF ₃ , GdF ₃ , BiF ₃ and LaF ₃ are highly effective in improving devitrification resistance by adding a small amount, but the amounts of YF ₃ , YbF ₃ , GdF ₃ and LaF ₃ are 15% and 15%, respectively. , 15%, 15%, exceeding 10%, the glass becomes unstable and easily devitrified, so the content is 0-15%, 0-15%, 0-15%, 0 It is desirable to suppress to 15% and 0 to 10%. More content of preferably YF ₃ 0 to 12%, and the content of YbF ₃ 0 to 12%, and the content of GdF ₃ 0 to 10%, and the content of BiF ₃ is 0-10%, of LaF ₃ The content is 0 to 7%, and the more preferable content of GdF ₃ is 0 to 8%.

MgF ₂ is a component having a function of imparting low dispersion characteristics to the glass. However, since the stability of the glass is reduced by excessive introduction, the content is preferably 0 to 20%.
CaF ₂ and SrF ₂ are components necessary for low dispersion while maintaining devitrification resistance. In particular, CaF ₂ plays a role of strengthening the glass structure in combination with AlF ₃ and is an indispensable component for stabilizing the glass. If the content of each of CaF ₂ and SrF ₂ is less than 2%, it cannot be said that the amount is sufficient from the viewpoint of improving the stability of the glass, and it becomes difficult to obtain a desired optical constant. Further, if both CaF ₂ and SrF ₂ are introduced in excess of 45%, there is a risk of destabilizing the glass. Therefore, the contents of CaF ₂ and SrF ₂ should both be in the range of 2 to 45%. Preferably, CaF ₂ is in the range of 5 to 40% and SrF ₂ is in the range of ₃ to 35%.
BaF ₂ is an effective component for improving durability and imparting low dispersion characteristics. However, since the stability is reduced by excessive introduction, its content is preferably 0 to 30%.
ZnF ₂ is a component that is effective in improving the stability and durability of glass. However, since the stability is reduced by excessive introduction, the content is preferably 0 to 20%.

LiF, NaF, and KF have the effect of improving the devitrification resistance and dispersibility of the glass by adding a small amount. However, when introduced excessively, the stability of the glass deteriorates rapidly and the durability deteriorates. The contents of NaF and KF are preferably 0 to 10%, 0 to 15% and 0 to 15%, respectively. More preferable contents of LiF, NaF, and KF are 0 to 5%, 0 to 10%, and 0 to 10%, respectively.
Li ₂ O, Na ₂ O, K ₂ O, MgO, CaO, SrO, BaO, ZnO are not essential components of the present invention, but the effect of improving the stability, weather resistance, and durability of the glass by introducing a small amount. However, since there is a possibility that the melting property of the glass may be deteriorated or the dispersibility may be deteriorated due to excessive introduction, each content is Li ₂ O 0-5%, Na ₂ O 0-5%, K _2. O 0-5%, MgO 0-5%, CaO 0-5%, SrO 0-5%, BaO 0-5%, ZnO 0-5%. More preferably _{Li 2 O 0~4%, Na 2} O 0~4%, K 2 O 0~4%, 0~4% MgO, CaO 0~4%, SrO 0~4%, BaO 0~4% ZnO 0 to 4%.

In addition to the above components, it is also possible to introduce a small amount of a compound such as Cl or Br for the purpose of defoaming or adjusting the optical constant. However, in consideration of the environmental impact, it is desirable not to introduce it as in the case of lead compounds and arsenic compounds.
Copper-containing fluorophosphate glass is also preferable as the glass used in the present invention. By introducing copper oxide based on fluorophosphate glass, near infrared absorption characteristics can be imparted. An optical element having near-infrared absorption characteristics can also be produced by precision press-molding a preform made of the above copper-containing fluorophosphate glass. Examples of the glass serving as the base include the above-mentioned fluorophosphate glass. Such an optical element can also be used as a color correction filter for a semiconductor image sensor such as a CCD or CMOS. For example, it can be formed into a thin plate to form the above filter, or a diffraction grating can be used to form an optical low-pass filter, or a lens can be formed into an optical element having both a color correction filter and a lens function, or can be diffracted on the lens surface. An optical element having both an optical low-pass filter function with a grating function, a lens function, and a color correction filter function can be provided.
The above various optical glasses can be obtained by heating and melting a glass raw material by a well-known method and molding a clarified and homogenized molten glass.

  Next, in the method for producing a glass article of the present invention, a preferable atmosphere when the molten glass is allowed to flow out will be described. When molten glass is exposed to an atmosphere containing moisture, a phenomenon occurs in which highly reactive components such as fluorine contained in the glass react with the moisture to generate HF and the like, and are detached from the glass surface. Then, the composition of the glass surface changes, and a deteriorated layer is formed on the surface, or when highly reactive components are detached from the glass, scale-like fine irregularities are generated. In press molding preforms, particularly precision press molding preforms and glass plate molding, high quality is required, so it is necessary to reduce the quality of the glass as much as possible. In the case of a precision press-molding preform, it is desired to prevent the occurrence of fine irregularities on the surface. Therefore, it is desirable that the atmosphere when the molten glass (particularly fluorine-containing glass such as fluorophosphate glass) flows out is a dry atmosphere. It is desirable that the molding atmosphere for molding the molten glass is also a dry atmosphere. In order to further reduce the amount of moisture in each of the above atmospheres, it is more desirable to perform the outflow and molding of the molten glass in a sealed space filled with a dry gas.

For example, the dry gas may be prepared by removing moisture in the gas through the desiccant or evaporating the liquefied gas. As examples of the liquefied gas, liquid nitrogen and liquid carbon dioxide can be shown as preferred examples. The liquid carbon dioxide is obtained by liquefying carbon dioxide under high pressure.
The dry gas preferably has a moisture content of 1000 ppm or less, more preferably 500 ppm or less, still more preferably 400 ppm or less, and even more preferably 380 ppm or less. The lower limit of the moisture content of the dry gas is not particularly limited, and is ideally 0 ppm, but the moisture content of the dry gas available in large quantities is 100 ppm or more. It is also preferable to use a gas having a dew point of −30 ° C. or lower as the dry gas.

Although there is no restriction | limiting in particular in the lower limit of the dew point of dry gas, The lower limit of the dew point of the gas which can be obtained in large quantities is about -80 degreeC. Further, a high-pressure gas can be used as the drying gas. For example, when high-pressure helium gas or high-pressure argon gas is used, a grade having a dew point of −60 ° C. or an ultra-high purity grade (dew point of −80 ° C.) may be designated. Therefore, gas can be used as dry gas from these high-pressure gases. However, since the dew point of the high-pressure gas may increase depending on the storage condition of the container, it is preferable to use the gas from the well-controlled high-pressure gas container. In addition, even if the gas has a moisture content or dew point that does not fall within the above range, it passes through a column filled with a desiccant such as synthetic zeolite, and the gas whose moisture content or dew point reaches a predetermined value is dried gas. It can also be used as
Examples of the gas include non-acidic gases such as nitrogen gas and a mixed gas of nitrogen and hydrogen (forming gas), inert gases (for example, argon gas, helium gas), carbon dioxide gas, gas mixed with the above gas, nitrogen Examples thereof include a gas in which any one of the above gases and oxygen is mixed, such as a mixed gas of oxygen and oxygen, and air.
The use of such an atmosphere greatly contributes to improving the quality of the glass article together with the effect of reducing the glass wetting on the outer periphery of the nozzle.

III. Manufacturing method of optical element The first aspect of the manufacturing method of the optical element of the present invention is to manufacture an optical element by heating the precision press-molding preform obtained by the above-described method for manufacturing a glass article and precision press-molding. It is characterized by doing.
Precision press molding is also called a mold optics molding method, which is already well known in the technical field to which the present invention belongs. A surface that transmits, refracts, diffracts, or reflects light rays of the optical element is called an optical functional surface. For example, taking a lens as an example, a lens surface such as an aspherical surface of an aspherical lens or a spherical surface of a spherical lens corresponds to an optical function surface. The precision press molding method is a method of forming an optical functional surface by press molding by precisely transferring a molding surface of a press mold to glass. That is, it is not necessary to add machining such as grinding or polishing to finish the optical functional surface.

According to the present invention, various lenses such as a spherical lens, an aspheric lens, and a micro lens, a diffraction grating, a lens with a diffraction grating, a lens array, various optical elements such as a prism, and applications include a digital camera and a camera with a built-in film. Various lenses such as lenses constituting imaging optical systems, imaging lenses mounted on camera-equipped mobile phones, and lenses for guiding light rays used for data reading and / or data writing on optical recording media such as CDs and DVDs An optical element can be manufactured. In addition, if a preform made of copper-containing glass is used, an optical element having a color correction function of a semiconductor imaging element can be produced.
These optical elements may be provided with an optical thin film such as an antireflection film, a total reflection film, a partial reflection film, or a film having spectral characteristics, if necessary.

Examples of the press mold used in the precision press molding method include known ones, for example, those having a release film on the molding surface of a mold material such as silicon carbide or cemented carbide material. preferable. As the release film, a carbon-containing film, a noble metal alloy film, or the like can be used, but a carbon-containing film is preferable from the viewpoint of durability and cost.
In the precision press molding method, it is desirable that the molding atmosphere be a non-oxidizing gas in order to keep the molding surface of the press mold in a good state. The non-oxidizing gas is preferably nitrogen or a mixed gas of nitrogen and hydrogen.

Next, a particularly preferable precision press molding method in the first embodiment of the optical element manufacturing method of the present invention will be described.
(Precision press molding method 1)
In this method, the preform is introduced into a press mold, the mold and the preform are heated together, and precision press molding is performed (referred to as precision press molding method 1).
In the precision press molding method 1, the temperature of the press mold and the preform is heated to a temperature at which the glass constituting the preform exhibits a viscosity of 10 ⁶ to 10 ¹² dPa · s to perform precision press molding. preferable.
In addition, the glass is cooled to a temperature at which the glass exhibits a viscosity of 10 ¹² dPa · s or more, more preferably 10 ¹⁴ dPa · s or more, more preferably 10 ¹⁶ dPa · s or more, and then the precision press-molded product is removed from the press mold. It is desirable to take it out.
Under the above conditions, the shape of the molding surface of the press mold can be accurately transferred with glass, and the precision press molded product can be taken out without being deformed.

(Precision press molding method 2)
In this method, after heating the preform, the preform is introduced into a press mold and precision press molding is performed. That is, the press mold and the preform are separately preheated, and the preheated preform is introduced into the press mold. Precision press molding (referred to as precision press molding method 2).
According to this method, since the preform is preliminarily heated before being introduced into the press mold, it is possible to manufacture an optical element with good surface accuracy free from surface defects while shortening the cycle time.
The preheating temperature of the press mold is preferably set lower than the preheating temperature of the preform. Thus, by lowering the preheating temperature of the press mold, the consumption of the mold can be reduced.
In addition, since it is not necessary to perform preform heating in the press mold, the number of press molds to be used can be reduced.

In the precision press molding method 2, it is preferable that the glass constituting the preform is preheated to a temperature exhibiting a viscosity of 10 ⁹ dPa · s or less, more preferably 10 ⁹ dPa · s.
The preform is preferably preheated while floating, and the glass constituting the preform is preferably 10 ^5.5 to 10 ⁹ dPa · s, more preferably 10 ^5.5 dPa · s to 10 ⁹ dPa · s. More preferably, it is preheated to a temperature showing a viscosity of less than s.
Moreover, it is preferable to start cooling the glass simultaneously with the start of pressing or in the middle of pressing.
The temperature of the press mold is adjusted to a temperature lower than the preheating temperature of the preform, and the temperature at which the glass exhibits a viscosity of 10 ⁹ to 10 ¹² dPa · s may be used as a guide.
In this method, it is preferable that after the press molding, the glass is cooled to a viscosity of 10 ¹² dPa · s or more and then released.
The precision press-molded optical element is taken out from the press mold and gradually cooled as necessary. Further, when the lens is molded, centering may be performed. Moreover, you may coat an optical thin film on the surface as needed.

According to a second aspect of the method for producing an optical element of the present invention, the optical element is produced through a step of press-molding a preform for press molding obtained by the method for producing a glass article.
More specifically, the plate-like optical glass obtained by the method for producing a glass article is cut in a state where distortion is reduced to produce, for example, rectangular parallelepiped or cubic glass pieces, and these glass pieces are barrel-polished. In accordance with the weight of the target press-formed product, the edges are rounded to roughen the surface. Next, a powder release agent such as boron nitride is uniformly applied to the entire surface of the glass piece, heated and softened, and press molded with a press mold to obtain a molded product having a shape approximate to the target optical element. Usually, heating, softening, and press molding of the glass piece are performed in the air. Then, the surface of the molded product is ground and polished to finish an optical element. Alternatively, a preform obtained by producing and annealing a glass molded body by the same method as in the first aspect of the method for producing a glass article of the present invention and barrel polishing is similarly heated and softened in the atmosphere. The optical element may be finished by press molding, grinding and polishing, or the glass piece may be polished to make a smooth surface preform, and the optical element may be made by precision press molding. .

A third aspect of the method for producing an optical element of the present invention is characterized in that an optical element is produced by machining a plate-like optical glass obtained by the method for producing a glass article.
Specifically, an optical element can be manufactured by slicing optical glass into a thin plate shape, or can be cut into blocks, ground, and polished to prepare an optical element such as a double-sided lens.
The method of the third aspect is suitable for producing a thin plate-like optical element such as a filter, and is suitable for producing a near-infrared absorption filter using the above-described copper ion-containing phosphate or fluorophosphate glass. is there. In the method of the third aspect, after slicing, a pair of opposing main surfaces are optically polished to finish an optical element.

  In any of the above methods of the first to third aspects, when the molten glass is flowed out to obtain a glass molded body, it is possible to reduce quality deterioration due to glass wetting on the outer periphery of the nozzle. The element can be manufactured with high productivity.

Next, the present invention will be described in more detail by way of examples.
(Example 1)
In order to obtain glasses 1 to 3 having the compositions and properties shown in Table 1, glass raw materials were weighed and mixed by a known method, and heated and melted in a platinum container to obtain various molten glasses. Next, the clarified and homogenized molten glass was sent to a pipe provided at the bottom of the melting vessel, and allowed to flow out at a constant flow rate from a nozzle connected to the lower end of the pipe. A vertical section of the nozzle is shown in FIG. This nozzle is a conduit 1 made entirely of pure gold, and an outlet 3 through which glass flows out is provided at the tip 2 to prevent devitrification of the glass and to stabilize the flow rate of glass. Heating and temperature are controlled.
Below the nozzle, a plurality of molds are placed on the turntable to sequentially receive the flowing glass and form it into a precision press-molding preform. The molten glass lump that has flowed out and separated by the formed mold is received one after another. The molten glass lump is molded into a preform while being floated on the mold by the gas ejected from the mold, cooled, and taken out from the mold. The mold from which the preform has been taken out is transferred again vertically below the nozzle. In this way, a preform with a constant weight is mass-produced from the molten glass by circulating and transferring the mold while the turntable is rotated as an index.
The glass 1 is _{P 2 O 5 -Nb 2 O 5} -Li 2 O system a high refractive index and high dispersion glass, the glass 2 is _P 2 _O 5 -BaO-ZnO-based high-refractive-index dispersion glass, glass 3 is low Dispersed fluorophosphate glass. When the preforms were formed by flowing out the glasses 1 and 2, the conventional 95Pt-5Au alloy nozzle caused the glass to rise to the outer periphery of the nozzle, but the pure gold nozzle of the present invention did not cause the glass to wet. In the molded preform, no striae or surface alteration was observed.

In the case of the glass 3, in the molding using the conventional nozzle, a surface striae layer was seen in the surface layer extending from the surface of the preform to the deep layer, but when the pure gold nozzle was used, Compared to the above, wetting did not occur. In addition, although a surface striae layer was found on the surface of the molded preform, the depth of the striae layer was shallower than when using a conventional nozzle, and the effect of using a pure gold nozzle was reduced. I was able to confirm. The surface striae layer can be removed by etching by immersing the entire preform in an acid or the like, or can be removed by polishing. As the striae layer becomes shallower, the surface glass to be removed becomes smaller and the time for the removal process can be shortened. Therefore, the productivity can be improved and the cost can be reduced.
In addition, the outflow and shaping | molding of the glasses 1 and 2 were performed in air | atmosphere, and the outflow and shaping | molding of the glass 3 were performed in dry air atmosphere.

(Example 2)
Next, the nozzle structure was the same as in Example 1, and a nozzle made of gold / platinum alloy consisting of 80% gold and 20% platinum by weight was produced. And the precision press molding preform which consists of various glasses of glass 1-3 was performed like Example 1, and the result similar to Example 1 was obtained.

(Example 3)
As shown in the vertical cross section of FIG. 5, a nozzle having a structure comprising a conduit portion 4 and a tip portion 5 is attached to a pipe, and various glasses 1 to 3 are caused to flow out from the outlet 7, and the preform is formed in the same manner as in the above embodiment. Was molded. The nozzle conduit part 4 is made of 95Pt-5Au alloy, and the tip part 5 is made of pure gold. The distal end portion 5 is attached to the conduit portion 4 by screws 6 so as to be in close contact so that there is no leakage in the glass flow path. A preform was molded using such a nozzle, and the same result as in Example 1 could be obtained.

Example 4
Next, the nozzle tip in Example 3 was replaced with a gold-platinum alloy made of gold 80% by weight and platinum 20% by weight, and the tip was attached in close contact with the conduit as in Example 3. Preforms made of various glasses 1 to 3 were molded. As a result, the same result as in Example 2 could be obtained.
The weight tolerance of the precision press-molding preforms produced in Examples 1 to 4 was within ± 1%.

(Example 5)
Various optical elements were produced by performing precision press molding using preforms for precision press molding made of various glasses 1 to 3 obtained in Examples 1 to 4.
Specifically, the preforms obtained in each of the above examples were heated, and an aspheric lens was obtained by precision press molding (aspheric precision press) using the press apparatus shown in FIG. The details of precision press molding are as follows.
As the forming die, an aspherical SiC upper die 11, lower die 12 and body die 13 were used. Then, after the preform 14 was allowed to stand between the upper mold 11 and the lower mold 12, the quartz tube 15 was heated by energizing the heater 16 with the interior of the quartz tube 15 being a nitrogen atmosphere. The temperature inside the mold is set to a temperature at which the glass yield point is +20 to 60 ° C., and while maintaining the same temperature, the push rod 17 is lowered and the upper mold 11 is pressed to precisely perform the preform 14 in the press mold. Press molded. In FIG. 6, 18 is a support base, 19 is a support rod, and 20 is a thermocouple.

The glass transition temperature is maintained in a state where the aspherical lens made of fluorophosphate glass formed by reducing the molding pressure after pressing is in contact with the upper die 11 and the lower die 12 at a molding pressure of 8 MPa and a molding time of 30 seconds. It was gradually cooled to a temperature of −30 ° C. and then rapidly cooled to room temperature. Thereafter, the aspherical lens was taken out from the press mold and subjected to shape measurement and appearance inspection. The obtained aspherical lens was a highly accurate lens. When this lens was observed, it was confirmed that it was a high-quality lens like the preform used.
It is preferable to provide a release film on the entire surface of the preform. Examples of the release film include a carbon film and a self-assembled film.
A high-quality, high-precision aspherical lens could be formed by introducing the preheated preform into a press mold and precision press molding.
The shape and dimensions of the preform may be appropriately determined depending on the shape of the precision press-molded product to be produced.
In the above embodiment, an aspherical lens is molded, but by using a press mold that matches the shape of the final product, various types such as a concave meniscus lens, a convex meniscus lens, a planoconvex lens, a biconvex lens, a planoconcave lens, a biconcave lens, etc. An optical element such as an aspherical lens or various spherical lenses, or a prism, a polygon mirror, or a diffraction grating can also be manufactured.
In addition, an optical multilayer film such as an antireflection film or a high reflection film can be formed on the optical functional surface of each optical element obtained as necessary.

(Example 6)
The glass raw materials were weighed and mixed by a known method so as to obtain glasses 1 to 3 as in the above examples, and heated and melted in a platinum container to obtain various molten glasses. Next, the clarified and homogenized molten glass was sent to a pipe provided at the bottom of the melting vessel, and flowed out at a constant flow rate from a nozzle connected to the lower end of the pipe. Below the nozzle, it has a flat bottom surface, and one of a pair of opposing side surfaces separated by a distance corresponding to the width of the glass plate to be molded and one of the two openings between the side surfaces is blocked. The mold was placed so that the bottom was horizontal. Then, the molten glass is continuously poured into the mold from the nozzle, and the glass plate formed from the opening of the mold is continuously horizontal at a constant speed so that the liquid level of the molten glass in the mold is kept constant. Pulled out. The drawn glass was subjected to strain removal through an annealing furnace, and then cut to a desired length to produce glass plates made of various optical glasses of glasses 1 to 3 having a certain width and plate thickness.

The nozzle used in the above method is entirely made of pure gold, the whole is made of gold / platinum alloy consisting of 80% by weight of gold and 20% by weight of platinum, the conduit part is made of 95Pt-5Au alloy and includes an outlet. Various nozzles were used in which the tip portion was made of pure gold, the conduit portion was made of 95Pt-5Au alloy, and the tip portion including the outlet was made of gold / platinum alloy consisting of 80% by weight gold and 20% by weight platinum. The attachment of the distal end portion to the conduit portion is as described in the third and fourth embodiments. In addition, in this example, since the outflow flow rate of the molten glass was larger than in Examples 1 to 4, the flow path diameter inside the nozzle was increased. Nozzle and pipe heating and temperature control are as described in the above embodiment.
In any of the nozzles, when the molten glass was allowed to flow out, no wetting up to the outer peripheral portion of the tip of the glass was observed.

(Example 7)
The glass plate produced in Example 6 was cut and divided into rectangular parallelepiped glass pieces. Next, these glass pieces were barrel-polished to round the edges and match the weight of the glass pieces to the weight of the intended press-formed product.
Next, the barrel-polished glass piece is used as a glass material for press molding, a known mold release agent is applied to the surface and heated in the atmosphere, and press molding in the air is performed to obtain a press molded product that approximates the lens shape. It was. After the press-molded product is annealed, it is finished into a lens whose surface is ground and polished. In this way, various lenses could be produced. An antireflection film or the like can be provided on the surface of the lens as necessary.

(Example 8)
Next, a glass plate made of a copper-containing fluorophosphate glass shown in Table 1 was formed in the same manner as in Example 6. After the glass plate was annealed, it was sliced into a thin plate shape and subjected to optical polishing on a pair of opposing main surfaces to produce a near infrared absorption filter.
This filter is suitable as a color correction filter for a solid-state imaging device such as a CCD or C-MOS.

  According to the present invention, a glass outflow nozzle capable of reducing the wetting of the glass to the outer peripheral portion of the glass outlet when the molten glass is eluted is provided. By using this glass outflow nozzle, a high-quality glass article is provided. Furthermore, an optical element can be obtained, and its industrial significance is extremely great.

It is a figure which shows the contact angle of the glass on a flat plate at the time of changing the platinum content of the flat plate which consists of gold | metal | money platinum alloys. It is a figure which shows how the contact angle of the glass on the flat plate which consists of either gold | metal | money and various gold alloys changes with temperature. It is a phase diagram of a gold / platinum alloy. It is a figure which shows an example of the nozzle of this invention. It is a figure which shows the other example of the nozzle of this invention. It is a figure which shows the precision press molding apparatus used in the manufacturing method of the optical element of this invention.

Explanation of symbols

A, B ... Nozzle 1 ... Conduit 2 ... Tip 3 ... Outlet 4 ... Conduit 5 ... Tip 6 ... Screw 7 ... Outlet 11 ... Upper mold 12 ... Lower mold 13 ... Body mold 14 ... Preform 15 ... Quartz Tube 16 ... Heater 17 ... Push rod 18 ... Support stand 19 ... Support rod 20 ... Thermocouple

Claims (13)

In the glass outflow nozzle that causes the molten glass to flow out from the outflow port provided at the tip,
A glass outflow nozzle characterized in that at least the entire tip including the outflow port is made of gold. In the glass outflow nozzle that causes the molten glass to flow out from the outflow port provided at the tip,
A glass outflow nozzle characterized in that at least the entire tip including the outlet is made of a gold / platinum alloy having a platinum content of 80% by weight or less.   The glass outflow nozzle according to claim 1 or 2, wherein the entire nozzle is made of the same kind of material.   A conduit portion provided with a flow path for molten glass inside and a tip portion attachable to the conduit portion are provided, and the molten glass is allowed to flow from the conduit portion to the outlet of the tip portion with the tip portion attached to the conduit portion. The glass outflow nozzle of any one of Claims 1-3 which has a structure in which a flow path is formed. In the method for producing a glass article, the molten glass is caused to flow out of the nozzle, and a glass article made of optical glass is formed.
The glass outflow nozzle of any one of Claims 1-4 is used as said nozzle, The manufacturing method of the glass article characterized by the above-mentioned.   The method for producing a glass article according to claim 5, wherein molten glass is caused to flow out of the nozzle, and glass having a constant weight is separated one after another to produce a precision press-molding preform made of optical glass as the glass article.   The molten glass is allowed to flow out of the nozzle, continuously cast into a mold and formed into a glass plate, and the glass plate formed from the mold is continuously drawn out to produce a plate-like optical glass as a glass article. Item 6. A method for producing a glass article according to Item 5.   The molten glass is allowed to flow out of the nozzle to produce a glass molded body made of optical glass, and the molded body is machined to produce a press molding preform made of optical glass as a glass article. The manufacturing method of the glass article of description.   The manufacturing method of the glass article of any one of Claims 5-8 whose said optical glass is phosphate glass or fluorophosphate glass.   A method for producing an optical element, comprising: heating a precision press-molding preform obtained by the method according to claim 6 and producing the optical element by precision press molding.   An optical element manufacturing method comprising manufacturing an optical element through a step of press-molding a press-molding preform obtained by the method according to claim 8.   A method of manufacturing an optical element, comprising: manufacturing an optical element by machining a plate-like optical glass obtained by the method according to claim 7.   The method for producing an optical element according to claim 10, wherein an optical element made of phosphate glass or fluorophosphate glass is produced.

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