WO2016159055A1 - Glass material for press molding, glass optical element, and method for producing same - Google Patents

Abstract

Provided are the following: a glass optical element which is provided with an oxide glass, a covering layer that covers at least a part of a surface of the oxide glass and that is a metal oxide film which is oxygen-deficient relative to the stoichiometric composition, and an intermediate layer provided between the oxide glass and the covering layer, wherein, in the intermediate layer, the speed at which oxygen atoms contained in the oxide glass diffuse at a temperature that is not lower than the glass transition temperature of the oxide glass is greater than the speed at which metal atoms contained in the metal oxide film diffuse at this temperature; a glass material for press molding; and a method for producing a glass optical element using the glass material for press molding.

Description

Glass material for press molding, glass optical element, and manufacturing method thereof Cross-reference of related applications

This application claims the priority of Japanese Patent Application No. 2015-73862 filed on March 31, 2015 and Japanese Patent Application No. 2015-243700 filed on December 15, 2015, all of which are described here. Specifically incorporated by reference.

The present invention relates to a glass material for press molding, a glass optical element, and a manufacturing method thereof.

As a method of manufacturing a glass optical element such as a glass lens (hereinafter also referred to as “optical element”), a method of press molding a glass material for press molding using an upper mold and a lower mold having opposed molding surfaces is known. It has been.

When molding an optical element by press molding, the glass material for press molding and the molding surface of the mold are in close contact with each other at a high temperature, so that a chemical reaction occurs at the interface between them, so Reaction traces or the like may occur, and the optical performance of the optical element obtained by press molding may deteriorate.

Conventionally, as a means for preventing the occurrence of the reaction mark, it has been proposed to provide one or more coatings on the surface of a glass material for press molding to suppress the reaction between the mold and the glass (for example, JP No. 2011-1259 (the entire description is specifically incorporated herein by reference).

By the way, as a result of the study by the present inventors, in the production of a glass optical element by press molding, the homogeneity of the optical element may be lowered due to the formation of fine bubbles (foaming) in the glass after press molding. It became clear. In order to provide an optical element having high optical performance, it is desired to suppress foaming in glass.
Therefore, the present inventors have intensively studied the cause of generation of bubbles in order to find a means for suppressing foaming in glass. As a result, an unexpected phenomenon was found in which bubbles generated in the optical element after press molding contained a large amount of oxygen even when press molding was performed in a non-oxidizing atmosphere. Since the cause of oxygen generation in press molding in a non-oxidizing atmosphere is only oxide glass, it is considered that oxygen derived from oxide glass is involved in the generation of bubbles.

One aspect of the present invention provides a means for suppressing the generation of bubbles in a glass optical element after press molding.

One embodiment of the present invention provides:
Oxide glass (hereinafter also referred to as “glass”);
A coating layer that is a metal oxide film that covers at least a part of the surface of the oxide glass and in which oxygen is lost from the stoichiometric composition;
An intermediate layer provided between the oxide glass and the coating layer;
With
In the intermediate layer, the rate of diffusion of oxygen atoms contained in the oxide glass at a temperature equal to or higher than the glass transition temperature of the oxide glass is greater than the rate of diffusion of metal atoms contained in the metal oxide film at the temperature. Fast, glass material for press molding,
About.

A further aspect of the present invention provides:
It has a pressing process to press-mold a glass material for press molding to form a press-molded body,
The method for producing a glass optical element, wherein the glass material for press molding is the glass material for press molding described above,
About.

A further aspect of the present invention provides:
Oxide glass,
A coating layer that is a metal oxide film that covers at least a part of the surface of the oxide glass and in which oxygen is lost from the stoichiometric composition;
An intermediate layer provided between the oxide glass and the coating layer;
With
In the intermediate layer, the rate of diffusion of oxygen atoms contained in the oxide glass at a temperature equal to or higher than the glass transition temperature of the oxide glass is greater than the rate of diffusion of metal atoms contained in the metal oxide film at the temperature. Fast, glass optics,
About.

As a result of intensive studies to suppress foaming in glass due to oxygen derived from oxide glass, the inventors of the present invention applied the above-mentioned coating on the oxide glass via the intermediate layer in the glass material for press molding. It led to providing a layer.
Although the above-described coating layer is a metal oxide film, it is in a state where oxygen is deficient from the stoichiometric composition, so that it is in a state where oxygen is easily taken in to approach the stoichiometric composition which is a more stable state. Therefore, if it is a metal oxide film in this state, it is possible to suppress the generation of bubbles by taking in oxygen that is generated in glass during press molding and causes foaming.
However, during press molding, migration (diffusion) of metal atoms contained in the coating layer can also occur from the coating layer toward the oxide glass side. If the effective thickness reduction or disappearance of the coating layer occurs due to this diffusion, it is difficult to suppress the generation of bubbles by the coating layer.
In contrast, in the intermediate layer, the rate at which oxygen atoms contained in the oxide glass diffuse at a temperature equal to or higher than the glass transition temperature of the oxide glass is such that the metal atoms contained in the metal oxide film at the temperature are Faster than spreading speed. Thereby, the diffusion of oxygen atoms from the oxide glass (movement toward the coating layer side) proceeds in preference to the diffusion of metal atoms from the coating layer. Therefore, the coating layer can efficiently take in oxygen atoms from the oxide glass into the coating layer without suppressing effective film thickness reduction or film disappearance, and suppress the generation of bubbles.
Moreover, the above-described coating layer and intermediate layer that have been subjected to a pressing step are present in the optical element thus obtained. Since the coating layer included in this optical element takes in oxygen atoms diffused from the oxide glass during press molding, the content of oxygen atoms relative to metal atoms is higher than that contained in the glass material for press molding. However, as a result of the study by the present inventors, it has been clarified that in one embodiment, the coating layer included in the optical element is still in a state where oxygen is lost from the stoichiometric composition.

According to one embodiment of the present invention, it is possible to provide a method for manufacturing an optical element capable of suppressing the generation of bubbles in glass during press molding.
Furthermore, according to one embodiment of the present invention, it is possible to provide a homogeneous optical element that does not generate bubbles.

FIG. 1 shows the rate of diffusion of oxygen atoms contained in oxide glass at a temperature equal to or higher than the glass transition temperature of oxide glass in the intermediate layer (T1) and the diffusion of metal atoms contained in the metal oxide film at this temperature. It is a model figure which shows the relationship with the speed (T2) to perform. FIG. 2 is a schematic cross-sectional view illustrating a press-molding glass material according to one embodiment of the present invention. FIG. 3 is a diagram illustrating an example of a press molding apparatus. FIG. 4 is a diagram showing the depth direction analysis result of secondary ionic strength by TOF-SIMS before press molding (glass material for press molding) in Example 1. FIG. 5 is a diagram showing the depth direction analysis results of secondary ion intensity by TOF-SIMS before press molding (glass material for press molding) in Example 2.

Hereinafter, the present invention will be described in more detail. Hereinafter, specific embodiments may be described with reference to the drawings, but the present invention is not limited to the embodiments shown in the drawings.

First, in the intermediate layer, the oxygen atom contained in the oxide glass at a temperature equal to or higher than the glass transition temperature of the oxide glass (T1) and the metal atom contained in the metal oxide film at the above temperature diffused. The relationship with the speed (T2) to be performed will be described. The relationship between T1 and T2 refers to the relationship between T1 and T2 at the same temperature that is equal to or higher than the glass transition temperature of the oxide glass.
FIG. 1 shows the rate of diffusion of oxygen atoms contained in oxide glass at a temperature equal to or higher than the glass transition temperature of oxide glass in the intermediate layer (T1) and the diffusion of metal atoms contained in the metal oxide film at this temperature. It is a model figure which shows the relationship with the speed (T2) to perform. In the press-molding glass material, as shown in FIG. 1, the oxide glass and the intermediate layer are in contact with each other. Further, the intermediate layer and the coating layer are in contact with each other. As shown in this model diagram, if the relationship of T1> T2 is satisfied in the intermediate layer, the diffusion of oxygen atoms from the oxide glass (movement toward the coating layer) is the diffusion of metal atoms from the coating layer. Proceeds with priority. As a result, the covering layer covers oxygen atoms from the oxide glass at a temperature higher than the glass transition temperature of the oxide glass, which is a temperature at which press molding is normally performed, without causing an effective decrease in film thickness or loss of the film. It is possible to efficiently incorporate into the layer and suppress the generation of bubbles.
The present inventors consider the reason why it is possible to suppress the generation of bubbles in the glass by performing press molding using the above glass material for press molding. However, the above description includes inferences by the present inventors, and the present invention is not limited to these inferences.
In addition, it can confirm that the intermediate | middle layer satisfy | fills the relationship of T1> T2 by the effective reduction | decrease of the film thickness of a coating layer, or the loss | disappearance of a film | membrane not generating after press molding.

Hereinafter, the glass material for press molding (also referred to as “preform” (PF)) will be described in more detail.

[Glass material for press molding]
FIG. 2 is a schematic cross-sectional view illustrating a press-molding glass material according to one embodiment of the present invention. In FIG. 2, the glass material PF for press molding for concave meniscus lenses is shown as an example.
The glass material for press molding shown in FIG. 2 includes an oxide glass 1, a coating layer 3 that covers at least a part of the surface of the oxide glass 1 and is a metal oxide film in which oxygen is lost from the stoichiometric composition, And an intermediate layer 2 provided between the oxide glass 1 and the coating layer 3. The coating layer 3 and the intermediate layer 2 only need to cover at least part of the surface of the oxide glass 1. That is, the oxide glass 1 may have an uncoated portion where the coating layer 3 and the intermediate layer 2 are not coated on a part of the surface, or the entire surface may be coated. In one embodiment, when a glass optical element is formed by press-molding a glass material for press molding, at least a portion of the oxide glass that will form the optical functional surface of the optical element can be covered. The optical functional surface means, for example, a region within the effective diameter in the optical element. However, oxygen atoms can be taken from the oxide glass as long as the covering layer 3 is present at least in any part of the surface of the glass material for press molding, and thus is not limited to the above-described embodiment.

Hereinafter, the covering layer, the intermediate layer, and the oxide glass constituting the glass material for press molding will be sequentially described.

<Coating layer>
The coating layer covering the oxide glass is a metal oxide film in which oxygen is lost from the stoichiometric composition. Therefore, the coating layer may be formed by a film formation method that can form such a metal oxide film. For example, after forming an intermediate layer, which will be described later, on the surface of a glass lump made of oxide glass, sputtering (vacuum deposition), CVD (Chemical Vapor Deposition) in a non-oxidizing atmosphere using a metal (single metal) as a target ) Method or the like, a metal oxide film deficient in oxygen from the stoichiometric composition can be formed. Here, the non-oxidizing atmosphere refers to an atmosphere made of a gas other than oxygen such as an inert gas such as argon gas or nitrogen gas. However, the presence of oxygen derived from a trace amount of oxygen unintentionally mixed as an impurity in the atmospheric gas is allowed.

The lower limit of the film forming temperature (the temperature of the glass lump) is preferably 150 ° C. or higher, and more preferably 200 ° C. or higher. The upper limit is preferably less than the glass transition temperature of the oxide glass. The upper limit temperature is, for example, 450 ° C. or less.

As a specific embodiment, a plurality of oxide glasses formed with an intermediate layer are arranged in a tray and placed in a vacuum chamber, and the oxide glass is heated to about 300 ° C. by a heater while evacuating the vacuum chamber. Heat to temperature. After evacuating until the degree of vacuum in the vacuum chamber becomes 1 × 10 ⁻⁵ Torr or less, argon (Ar) gas is introduced, and the atmosphere gas in the vacuum chamber is replaced with Ar gas, and then a high frequency is applied to the target substrate. Then, the raw material is turned into plasma, and a coating layer is formed on the surface of the oxide glass on which the intermediate layer is formed. The film thickness of the coating layer can be controlled to a desired film thickness by adjusting the pressure (vacuum degree) in the vacuum chamber, the power source power, and the film formation time. In addition, the coating layer should just cover at least one part of the surface of oxide glass. This point is as described above.

The coating layer may be a metal oxide film in which oxygen is lost from the stoichiometric composition, and the metal constituting the metal oxide is not particularly limited. Specific examples of the metal constituting the coating layer include zirconium, yttrium, tantalum, niobium, and tungsten. However, the metal which is not illustrated here may be sufficient. In the present invention, the term “metal” is used to include those classified as semi-metals. For example, as an example, silicon (Si) is also included in the metal in the present invention.

The film thickness of the coating layer is preferably 0.5 nm or more and more preferably 1.5 nm or more in order to efficiently take in oxygen from the oxide glass. On the other hand, from the viewpoint of preventing spiders, the thickness of the coating layer is preferably 15 nm or less, and more preferably 10 nm or less.

As described above, the coating layer described above is in a state where oxygen is lost from the stoichiometric composition. For example, in the case of zirconium oxide, since the stoichiometric composition is ZrO ₂ , when the coating layer is a zirconium oxide film, the composition is ZrOx (x <2). Here, x may be less than 2, and is not particularly limited. The same applies to other metal oxide films.

<Intermediate layer>
The intermediate layer is provided between the coating layer and the oxide glass. Note that the glass material for press molding only needs to have a coating layer on at least a part of the surface of the oxide glass via an intermediate layer, and a part of the surface of the oxide glass is covered only with the intermediate layer. There may be a portion that is covered, or there may be a portion that is covered only with the covering layer. The rate (T1) at which the oxygen atoms contained in the oxide glass diffuse in the intermediate layer at a temperature equal to or higher than the glass transition temperature of the oxide glass is that the metal atoms contained in the metal oxide film (coating layer) diffuse. Faster than speed (T2). Thus, as long as the relationship of T1> T2 is satisfied in the intermediate layer at a temperature equal to or higher than the glass transition temperature of the oxide glass, the material and film thickness of the intermediate layer are not limited. For example, the intermediate layer can be formed using a compound of one or more metal elements and one or more elements selected from the group consisting of oxygen, nitrogen, carbon, and fluorine. The intermediate layer is, for example, a metal oxide film, and examples of the metal oxide film include zirconium, yttrium, scandium, and lanthanoid oxide films. Examples of lanthanoids include lanthanum, cerium, praseodymium, samarium, and ytterbium. These are merely examples and are not limited to the materials described above. The film thickness of the intermediate layer can be, for example, in the range of 1 to 15 nm, but it is sufficient that the relationship of T1> T2 is satisfied at a temperature equal to or higher than the glass transition temperature of the oxide glass, and the film thickness is outside this range. May be. The intermediate layer may be a single layer or a multilayer structure having two or more layers. In the case of a multilayer structure, the film thickness of the intermediate layer refers to the total film thickness of the multilayer. The intermediate layer of the multilayer structure only needs to satisfy the relationship of T1> T2 in the entire multilayer structure.

As a method for forming the intermediate layer, a known film forming method such as a sputtering method or a vacuum evaporation method can be used. For example, the intermediate layer can be formed on at least a part of the surface of the oxide glass by a sputtering method using argon gas. By performing preliminary experiments as appropriate, it is possible to determine the film forming conditions for forming the intermediate layer satisfying the relationship of T1> T2. For example, after carrying out a preliminary experiment to produce a test press-molding glass material and performing a test press, the film forming conditions that have been confirmed to have no significant decrease in the film thickness of the coating layer or disappearance of the film are actually It can employ | adopt as film-forming conditions for forming the intermediate | middle layer of the glass material for press moldings used for this press molding.

<Oxide glass>
Examples of the oxide glass include optical glasses having various compositions that are usually used in the production of optical elements. Specific examples of such optical glass include boric acid-rare earth glass such as lanthanum borate glass, phosphate glass, and silicate glass.

By the way, as a composition in which foaming tends to be caused by pressing in the optical glass, an oxide glass containing a relatively large amount of Nb ₂ O ₅ , TiO ₂ , WO ₃ , and Ta ₂ O ₅ as high refractive index imparting components. Can be mentioned. These metal oxides are considered to be more easily reduced than the other metal oxides at the glass transition temperature or higher. In the method for producing a glass optical element according to one aspect of the present invention, for example, the glass optical element includes one or more high refractive index imparting components selected from the group consisting of Nb ₂ O ₅ , TiO ₂ , WO ₃ and Ta ₂ O ₅ , and high An oxide glass having a total content of refractive index imparting components (Nb ₂ O ₅ + TiO ₂ + WO ₃ + Ta ₂ O ₅ ) of 10% by mass or more may be press-molded after providing the above intermediate layer and coating layer. it can. Thereby, a homogeneous optical element in which the generation of bubbles after pressing is suppressed can be obtained. The total content (Nb ₂ O ₅ + TiO ₂ + WO ₃ + Ta ₂ O ₅ ) is more preferably 15% by mass or more. The total content (N _b O ₅ + TiO ₂ + WO ₃ + Ta ₂ O ₅ ) is 50% by mass or less, which suppresses the increase in the press temperature due to a significant increase in the glass transition temperature and the yield point, and the glass. From the viewpoint of ease of conversion, it is preferably 45% by mass or less.

Since the press temperature is usually performed at a temperature equal to or higher than the glass transition temperature of the oxide glass, the press temperature tends to be higher as the glass has a higher glass transition temperature. On the other hand, a significant increase in the press temperature may promote the generation of bubbles. Therefore, as a preferable specific embodiment of the oxide glass, an oxide glass containing an appropriate amount of one or more glass components having an action of lowering the glass transition temperature can be exemplified. Examples of the glass component having an action of lowering the glass transition temperature include ZnO and an alkali metal oxide selected from the group consisting of Li ₂ O, Na ₂ O and K ₂ O. The total content of ZnO and alkali metal oxide (ZnO + Li ₂ O + Na ₂ O + K ₂ O) is preferably 5% by mass or more, and more preferably 10% by mass or more. On the other hand, from the viewpoint of ease of vitrification, the total content (ZnO + Li ₂ O + Na ₂ O + K ₂ O) is preferably 25% by mass or less, and more preferably 20% by mass or less. Specific examples of the oxide glass include an optical glass having a refractive index nd of 1.70 to 2.10 and an Abbe number νd of 20 to 55 from the viewpoint of the usefulness of the optical element. Further, as another specific embodiment, an optical glass satisfying one or both of a glass transition temperature of 630 ° C. or lower and a yield point of 680 ° C. or lower is exemplified as a glass excellent in press moldability, particularly precision press moldability. You can also However, the method for manufacturing an optical element according to one embodiment of the present invention is not limited to the specific embodiment described above.

As a more specific aspect of the optical glass that can be an oxide glass, for example, the following glasses I, II, and III can be mentioned. However, the composition of the oxide glass is not particularly limited. Glasses I, II, and III are all suitable as optical glasses for producing glass optical elements. According to one embodiment of the present invention, such an optical glass can be press-molded to provide a high-quality glass optical element free from bubbles in the glass.

(Glass I)
In cation% display,
B ³⁺ and Si ⁴⁺ in total 5 to 60% (however, B ³⁺ is 5 to 50%),
Zn ²⁺ and Mg ²⁺ in total 5% or more,
La ³⁺ , Gd ³⁺ , Y ³⁺ and Yb ³⁺ in total 10 to 50%,
Ti ⁴⁺ , Nb ⁵⁺ , Ta ⁵⁺ , W ⁶⁺ and Bi ³⁺ in total 6 to 45% (provided that the total content of Ti ⁴⁺ and Ta ⁵⁺ exceeds 0% and W ⁶⁺ Content over 5%),
Including
The cation ratio of the Si ⁴⁺ content to the B ³⁺ content (Si ⁴⁺ / B ³⁺ ) is 0.70 or less,
Ti ⁴⁺ and Ta ⁵⁺ content of the cation ratio of Ta ⁵⁺ to the total content of ^{(Ta 5+ / (Ti 4+ +} Ta 5+)) is not less 0.23 or more,
The cation ratio of the W ⁶⁺ content to the total content of Nb ⁵⁺ and W ⁶⁺ (W ⁶⁺ / (Nb ⁵⁺ + W ⁶⁺ )) is 0.30 or more,
Cation ratio of the total content of Ti ⁴⁺ , Nb ⁵⁺ , Ta ⁵⁺ , W ⁶⁺ and Bi ^{3+ to} the total content of B ³⁺ and Si ⁴⁺ ((Ti ⁴⁺ + Nb ⁵⁺ + Ta ⁵⁺ + W ⁶⁺ + Bi ³⁺ ) / (B ³⁺ + Si ⁴⁺ )) is more than 0.37 and not more than 3.00,
Cation ratio of the total content of Zn ²⁺ , Mg ²⁺ and Li ^{+ to} the total content of La ³⁺ , Gd ³⁺ , Y ³⁺ and Yb ³⁺ ((Zn ²⁺ + Mg ²⁺ + Li ⁺ ) / ( La ³⁺ + Gd ³⁺ + Y ³⁺ + Yb ³⁺ )) is 0.40 or more,
The refractive index nd is 1.90 to 2.00, and the Abbe number νd is the following formula (1):
25 ≦ νd <(3.91−nd) /0.06 (1)
An oxide glass that meets the requirements.

Although the glass I is a high refractive index glass, it can exhibit a low glass transition temperature, and thus is suitable as a glass for precision press molding. In a preferred embodiment, the glass transition temperature is 650 ° C. or lower. Optical glass having a glass transition temperature of 650 ° C. or lower can maintain the glass temperature during precision press molding in a relatively low temperature range, suppresses the reaction between the glass during press molding and the press molding surface, and is precise. The press formability can be maintained in a good state. From such a viewpoint, the glass transition temperature is preferably 640 ° C. or less, more preferably 630 ° C. or less, further preferably 620 ° C. or less, further preferably 610 ° C. or less, and 600 ° C. More preferably, it is the following.
It should be noted that if the glass transition temperature is excessively decreased, the stability of the glass decreases or the refractive index tends to decrease. Therefore, the glass transition temperature is preferably 500 ° C. or higher, and preferably 520 ° C. or higher. More preferably, it is 540 ° C. or more, further preferably 560 ° C. or more, and further preferably 570 ° C. or more.

(Glass II)
B ₂ O ₃ , La ₂ O ₃ and ZnO are included, and expressed in mol%, B ₂ O ₃ 20 to 60%, SiO ₂ 0 to 20%, ZnO 22 to 42%, La ₂ O ₃ 5 to 24%, _{Gd 2 O 3 0 ~ 20%} ( provided that the total of La ₂ O ₃ and Gd ₂ O ₃ is _{10 ~ 24%), ZrO 2} 0 ~ 10%, Ta 2 O 5 0 ~ 10%, WO 3 0 ~ 10%, Nb ₂ O ₅ 0-10%, TiO ₂ 0-10%, Bi ₂ O ₃ 0-10%, GeO ₂ 0-10%, Ga ₂ O ₃ 0-10%, Al ₂ O ₃ 0- 10%, BaO 0 to 10%, Y ₂ O ₃ 0 to 10% and Yb ₂ O ₃ 0 to 10%, and an Abbe number (ν _d ) of 40 or more and substantially free of lithium Glass.

Concerning Glass II, “substantially free of lithium” means that the amount of Li ₂ O introduced is suppressed to a level that does not cause spiders or burns that hinder the use of the glass surface as an optical element. It is. Specifically, it means that the content is reduced to less than 0.5 mol% in terms of the amount of Li ₂ O. Since the risk of spider and burns can be reduced as the amount of lithium is reduced, the amount of Li ₂ O is preferably suppressed to 0.4 mol% or less, and more preferably to 0.1 mol% or less. Preferably, it is more preferable not to introduce.

Glass II is suitable for precision press molding, and it is preferable that the glass transition temperature is low in order to prevent wear of the press mold and damage to the release film formed on the molding surface of the mold. It is preferable that it is 630 degrees C or less, and it is more preferable that it is 620 degrees C or less. On the other hand, in order to prevent spiders and burns on the glass surface, in order to limit the amount of lithium in the glass as described above, if the glass transition temperature is excessively lowered, the refractive index decreases or the stability of the glass Problems such as lowering of the Therefore, the glass transition temperature is more preferably 530 ° C. or higher, and further preferably 540 ° C. or higher.

For details of the glass II, reference can be made to paragraphs 0013 to 0039 of JP-A-2006-137661 (the entire description is specifically incorporated herein by reference).

(Glass III)
In mol%
SiO ₂ 0-20%,
B ₂ O ₃ 5-40%,
SiO ₂ + B ₂ O ₃ = 15-50%,
Li ₂ O 0-10%,
ZnO 12-36%,
However, 3 × Li ₂ O + ZnO ≧ 18%,
La ₂ O ₃ 5-30%,
Gd ₂ O ₃ 0-20%,
Y ₂ O ₃ 0-10%,
La ₂ O ₃ + Gd ₂ O ₃ = 10-30%,
La ₂ O ₃ / ΣRE ₂ O ₃ = 0.67 to 0.95%,
(However, ΣRE ₂ O ₃ = La ₂ O ₃ + Gd ₂ O ₃ + Y ₂ O ₃ + Yb ₂ O ₃ + Sc ₂ O ₃ + Lu ₂ O ₃ )
ZrO ₂ 0.5-10%,
Ta ₂ O ₅ 1-15%,
WO ₃ 1-20%,
Ta ₂ O ₅ / WO ₃ ≦ 2.5 (molar ratio)
Nb ₂ O ₅ 0-8%,
TiO ₂ 0-8%
Including
Refractive index nd is 1.87 or more,
An oxide glass having an Abbe number νd of 35 or more and less than 40.

Glass III exhibits a low-temperature softening property with a glass transition temperature of 650 ° C. or lower. A more preferable range of the glass transition temperature of the glass III is 640 ° C. or lower, more preferably 630 ° C. or lower, more preferably 620 ° C. or lower, and still more preferably 610 ° C. On the other hand, if the glass transition temperature is excessively decreased, it is difficult to achieve higher refractive index and lower dispersion and / or the stability and chemical durability of the glass tend to decrease. Is 510 ° C. or higher, preferably 540 ° C. or higher, more preferably 560 ° C. or higher, and even more preferably 580 ° C. or higher.

Furthermore, the preferable range of the yield point of the glass III is 700 ° C. or less, more preferably 690 ° C. or less, further preferably 680 ° C. or less, more preferably 670 ° C. or less, and still more preferably 660 ° C. or less. When the yield point is excessively lowered, it is difficult to achieve higher refractive index and lower dispersion, and / or the stability and chemical durability of the glass tend to be lowered. Therefore, the yield point is preferably 550 ° C. or higher, more preferably 580 ° C. or higher, even more preferably 600 ° C. or higher, and even more preferably 620 ° C. or higher.

For details of the glass III, reference can be made to paragraphs 0016 to 0065 of JP-A-2008-201661 (the entire description is specifically incorporated herein by reference).

(Formation of oxide glass)
The oxide glass can be formed into a shape known as a glass material for press molding by a method known as a method for forming a glass material for press molding. Regarding the shape and forming method of the oxide glass, for example, paragraphs 0087 to 0106 of JP2011-1259A and description of Examples, JP2004250295A (the entire description is specifically incorporated herein by reference) Reference may be made to paragraphs 0040-0044 and the description of the examples.

<Arbitrary film>
The glass material for press molding according to one embodiment of the present invention can be obtained by performing a film forming process for forming the above-described intermediate layer and coating layer on the oxide glass described above. In the glass material for press molding, one or more layers can be arbitrarily formed on the above-described coating layer. Such a coating is effective in enhancing the mold releasability of the glass from the mold during press molding.

As an aspect of the above-mentioned arbitrary coating, a carbon-containing film can be exemplified. When a glass material for press molding (hereinafter also referred to as “glass material”) is supplied to the mold prior to pressing, the carbon-containing film provides sufficient slipperiness with the mold and the glass material is molded. It enables smooth movement to a predetermined position (center position) of the mold. Can help. Furthermore, when the press-molded body is cooled to a predetermined temperature after pressing, it is useful in that the glass is easily separated from the surface of the mold and assists the mold release. Moreover, laminating a carbon-containing film on the above-described coating layer is also effective in suppressing the occurrence of cracking during press molding.

As the carbon-containing film, a film containing carbon as a main component is preferable, but a film containing a component other than carbon such as a hydrocarbon film may be used. As a method for forming the carbon-containing film, a known film forming method such as vacuum deposition using a carbon raw material, sputtering, ion plating method, plasma CVD (Chemical Vapor Deposition) can be used. Further, a carbon-containing film may be formed by thermal decomposition of a carbon-containing material such as hydrocarbon.

[Glass optical element, manufacturing method of glass optical element]
One embodiment of the present invention provides:
Oxide glass,
A coating layer that is a metal oxide film that covers at least a part of the surface of the oxide glass and in which oxygen is lost from the stoichiometric composition;
An intermediate layer provided between the oxide glass and the coating layer;
With
In the intermediate layer, the rate of diffusion of oxygen atoms contained in the oxide glass at a temperature equal to or higher than the glass transition temperature of the oxide glass is greater than the rate of diffusion of metal atoms contained in the metal oxide film at the temperature. Fast, glass optics,
About.

According to one aspect of the present invention, the press-molded glass material described above is prepared and then press-molded to obtain a press-molded body itself or by subjecting the press-molded body to a post-process such as film formation. A glass optical element can be obtained.

Press molding can be performed by a known press molding method as a method for molding an optical element. Hereinafter, although a specific aspect is demonstrated, this invention is not limited to the following aspect.

As a mold used for press molding, a precision material made of a dense material having sufficient heat resistance and rigidity can be used. Examples include metals such as silicon carbide, silicon nitride, tungsten carbide, aluminum oxide, titanium carbide, and stainless steel, or those whose surfaces are coated with a film of carbon, refractory metal, noble metal alloy, carbide, nitride, boride, etc. be able to. As the film covering the molding surface, a film containing carbon is preferable from the viewpoint that a glass material for press molding can be molded into a glass optical element without fusing, spidering, scratching, or the like. JP, 2011-1259, A paragraph 0116 can be referred to about a carbon content film. By using a molding die having a carbon-containing release film on the molding surface as the molding die, there is an advantage that the slipperiness between the molding surface and the glass material is increased and the moldability is further improved.

FIG. 3 is a diagram showing an example of a press molding apparatus. In press molding, as shown in FIG. 3, the oxide glass 1 is coated with an intermediate layer 2 and a coating layer 3 in a molding die 7 including an upper die 4, a lower die 5 and a body die 6. A glass material PF is supplied and the temperature is raised to a temperature range suitable for pressing.

For example, the heating temperature of the glass material PF for press molding is appropriately set depending on the type of the oxide glass 1, but is set to a temperature range in which the viscosity of the oxide glass 1 is 10 ⁵ to 10 ¹⁰ dPa · s. It is preferable to perform press molding in the temperature range. Pressing temperature, for example, set oxide glass 1 temperature more preferably to be 10 ^7.2 dPa · s corresponds longitudinal 10 ⁶ ~ 10 ⁸ dPa · s, as oxide glass 1 is 10 ^7.2 dPa · s corresponds More preferably. Usually, the press temperature is set to a temperature equal to or higher than the glass transition temperature of the oxide glass. For press molding in which oxide glass is coated with a coating layer, which is a metal oxide film in which oxygen is lost from the stoichiometric composition, and an intermediate layer satisfying the relationship of T1> T2 at such a temperature. By performing press molding of the glass material, it is possible to prevent bubbles from being generated in the press-molded body obtained by press molding by incorporating oxygen atoms that cause foam generation into the metal oxide film. Note that the press temperature and the heating temperature related to the press refer to the temperature of the atmosphere in which press molding is performed. Press molding can be performed by applying a predetermined load to the upper die 4.

In press molding, the glass material PF for press molding is supplied to the mold 7 and both the glass material PF for press molding PF and the mold 7 may be heated to a predetermined range, or the glass material PF for press molding PF and molding may be used. The glass material PF for press molding may be placed in the molding die 7 after the molds 7 are heated to a predetermined temperature range. Further, the glass material PF for press molding is heated to a temperature equivalent to 10 ⁵ to 10 ⁹ dPa · s, and the mold 6 is heated to a temperature corresponding to 10 ⁹ to 10 ¹² dPa · s in terms of glass viscosity. Alternatively, a method may be employed in which the material is placed in the mold 7 and press-molded immediately. In this case, since the mold temperature can be relatively lowered, the temperature increase / decrease cycle time of the molding apparatus can be shortened, and deterioration of the mold 7 due to heat can be suppressed, which is preferable. In either case, cooling is started at or after the start of press molding, and the temperature is lowered while applying an appropriate load application schedule and maintaining close contact between the molding surface and the glass material PF. Then, it molds and takes out a press molding. The mold release temperature is preferably 10 ^12.5 to 10 ^13.5 dPa · s.

In one aspect, since the coated layer (metal oxide film) provided on the press-molding glass material PF has taken in oxygen atoms from the oxide glass, the release-molded press-molded body is more than before press molding. In addition, there is a coating layer having a high oxygen content, that is, a metal oxide film in which the oxygen atom content to metal atoms is higher than the coating layer provided in the glass material for press molding before press molding. In one embodiment, the metal oxide film is in a state where oxygen is deficient rather than the stoichiometric composition. In one embodiment, the press-molded body after press molding is provided between the oxide glass, a coating layer covering at least part of the surface of the oxide glass, and the oxide glass and the coating layer. An intermediate layer. Here, in one aspect, the coating layer included in the press-molded body is a metal oxide film in a state where oxygen is lost from the stoichiometric composition. In one embodiment, in the intermediate layer provided in the press-molded product, the rate at which oxygen atoms contained in the oxide glass diffuse at a temperature equal to or higher than the glass transition temperature of the oxide glass is determined by the metal oxide film at the temperature. Faster than the diffusion rate of metal atoms contained in.
However, various aspects other than the above aspects are also included in the present invention as one aspect of the present invention.

The press-molded body that has been press-molded can be shipped as an optical element as a final product as it is, or post-processing such as centering and film formation that forms an optical functional film such as an antireflection film on the surface. It can also be made the final product after applying. For example, a desired shape can be obtained by appropriately forming a material such as Al ₂ O ₃ , ZrO ₂ —TiO ₂ , or MgF ₂ on a press-molded body having the above-described coating layer after press molding, as a single layer or by stacking. An antireflection film can be formed. The antireflection film can be formed by a known method such as vapor deposition, ion-assisted vapor deposition, ion plating, or sputtering. For example, in the case of the vapor deposition method, the vapor deposition material is heated by an electron beam, direct energization or arc in a vacuum atmosphere of about 10 ⁻⁴ Torr using a vapor deposition apparatus, and the material generated by evaporation and sublimation from the material is used. The antireflection film can be formed by transporting the vapor onto the substrate and condensing / depositing it. The heating temperature of the press-molded product can be about room temperature to about 400 ° C. However, when the glass transition temperature of the oxide glass constituting the press-formed body is 450 ° C. or lower, the upper limit temperature for heating the press-formed body is preferably set to the glass transition temperature −50 ° C.

An optical element according to one embodiment of the present invention is a small-diameter, thin-walled small-mass lens, for example, a small imaging system lens, a communication lens, an optical pickup objective lens, a collimator lens, and the like mounted on a portable imaging device. be able to. The lens shape is not particularly limited, and various shapes such as a convex meniscus lens, a concave meniscus lens, a biconvex lens, and a biconcave lens can be taken.

Hereinafter, the present invention will be further described based on examples. However, the present invention is not limited to the embodiment shown in the examples.

The glass transition temperature and yield point described below are values measured at a heating rate of 4 ° C./min with a thermomechanical analyzer of Rigaku Corporation.
The refractive index nd and the Abbe number νd were measured for the optical glass obtained at a slow cooling rate of −30 ° C./hour.

1. Production of glass materials for press molding and production of optical elements

[Comparative Example 1]
(1) Production of glass material for press molding As the oxide glass of the glass material for press molding, optical glass III-1 described in Table 1 belonging to the glass III described above was used.
First, an oxide glass was dropped from a molten state onto a receiving mold and cooled, and a glass lump having a shape with one surface and the other surface as a convex surface was preformed. A ZrO ₂ film (film thickness: about 5 nm) and a SiO ₂ film (film thickness: about 5 nm), which are surface layers in Examples 1 to 6 of JP 2011-1259 A, are applied to the preformed glass block. Were formed in this order by the method described in the publication to obtain a glass material for press molding. The external dimensions of the obtained glass material for press molding were 17 to 18 mm, and the center thickness was 7 to 8 mm.

(2) Production of Press Molded Body by Precision Press Molding Next, the glass material for press molding produced in the above (1) was press molded in a nitrogen gas atmosphere by a precision press molding apparatus. In other words, a SiC upper and lower mold in which a carbon-containing release film is formed on the molding surface by a sputtering method and a molding mold consisting of a barrel mold, and the atmosphere in the chamber of the molding apparatus is filled with non-oxidizing N ₂ gas. The oxide glass was heated to a temperature at which the viscosity of the oxide glass was 10 ^7.2 dPa · s, and supplied to a mold heated to a temperature equivalent to 10 ^8.5 dPa · s as the viscosity of the oxide glass. Immediately after the supply, the glass material for press molding is pressed between the upper and lower molds (press temperature 675 ° C.), and the glass material for press molding and the upper and lower molds are kept in close contact with each other up to a temperature below the annealing temperature of the oxide glass. After cooling, the press-molded body was taken out from the mold. The outer diameter of the press-molded body was 26.0 mm, and the center wall thickness was 4.0 mm. Next, the outer peripheral portion of the press-molded body was centered by grinding to obtain a biconvex aspherical glass lens having a diameter of 22 mm.

[Example 1]
Instead of the SiO ₂ film of Comparative Example 1, a zirconium oxide film (film thickness: about 5 nm) was formed as a coating layer on the ZrO ₂ film. Film formation was performed by sputtering using metal zirconium (Zr) as a target in an Ar 100% atmosphere at a film formation temperature of 300 ° C., and the film thickness was adjusted by sputtering conditions. The ZrO ₂ film as an intermediate layer was directly formed on the oxide glass. The zirconium oxide film as the coating film was directly formed on the ZrO ₂ film as the intermediate layer.
The glass material for press molding thus obtained has a zirconium oxide film as a coating layer and a ZrO ₂ film as an intermediate layer. Using this glass material for press molding, an aspheric glass lens was obtained by the same method as described above.

[Example 2]
A glass material for press molding was obtained in the same manner as in Example 1 except that a coating layer having a thickness of about 5 nm was formed using metal yttrium (Y) instead of metal zirconium.
Using the glass material for press molding thus obtained, an aspheric glass lens was obtained by the same method as described above.

[Comparative Example 2]
A glass material for press molding was obtained in the same manner as in Example 2 except that the intermediate layer was not formed.
Using the glass material for press molding thus obtained, an aspheric glass lens was obtained by the same method as described above.

[Example 3]
A glass material for press molding was obtained in the same manner as in Example 1 except that a coating layer having a thickness of about 5 nm was formed using metal tantalum (Ta) instead of metal zirconium.
Using the glass material for press molding thus obtained, an aspheric glass lens was obtained by the same method as described above.

[Example 4]
A glass material for press molding was obtained in the same manner as in Example 1 except that a coating layer having a thickness of about 5 nm was formed using metal niobium (Nb) instead of metal zirconium.
Using the glass material for press molding thus obtained, an aspheric glass lens was obtained by the same method as described above.

[Example 5]
A glass material for press molding was obtained in the same manner as in Example 1 except that a coating layer having a thickness of about 5 nm was formed using metal tungsten (W) instead of metal zirconium.
Using the glass material for press molding thus obtained, an aspheric glass lens was obtained by the same method as described above.

[Example 6]
A glass material for press molding was obtained in the same manner as in Example 1 except that a coating layer having a thickness of about 5 nm was formed using metal titanium (Ti) instead of metal zirconium.
Using the glass material for press molding thus obtained, an aspheric glass lens was obtained by the same method as described above.

[Comparative Example 3]
Except that deposited as a coating layer Y ₂ O ₃ film having a thickness of about 5nm by using Y ₂ O ₃ instead of the metal zirconium was obtained in the same manner as the glass material for press molding as in Example 1.
Using the glass material for press molding thus obtained, an aspheric glass lens was obtained by the same method as described above.

2. Appearance evaluation of optical element When observed with an optical microscope at a magnification of 10 to 50 times, bubbles with a diameter of 50 μm or more are less than 1 bubble, bubbles with a diameter of 25 μm or more are less than 2 bubbles, or bubbles with a diameter of 10 μm or more That the number of bubbles is less than 5 and the total diameter of the bubbles does not exceed 50 μm can be used as an index (hereinafter referred to as “appearance index 1”) that is a homogeneous optical element in which the generation of bubbles is suppressed.
More preferably, the number of bubbles having a diameter of 25 μm or more is less than 1 or the number of bubbles having a diameter of 10 μm or more is less than 3 when observed with an optical microscope at a magnification of 10 to 50 times, and the total diameter of the bubbles That does not exceed 25 μm can be used as an index (hereinafter referred to as “appearance index 2”) that is a homogeneous optical element without bubbles.
Here, the total diameter of the bubbles is, for example, 100 μm if there are two bubbles having a diameter of 50 μm. In addition, the diameter here refers to the diameter when the bubble is a circular bubble, the distance in the longitudinal direction when the bubble is elliptical, and the longest possible distance when the bubble is irregular. To do.
Each lens produced in Examples and Comparative Examples was observed with an optical microscope at a magnification of 50 times, and appearance index 1 and appearance index 2 were evaluated. For each appearance index, the results are shown in Table 2 with ◯ being satisfied and × being not satisfied.

As shown in Table 2, in Examples 1 to 6, the appearance indices 1 and 2 were both good, whereas in Comparative Examples 1 to 3, both the appearance indices 1 and 2 were x.
Since the coating layers of Examples 1 to 6 are metal oxide films formed in a non-oxidizing atmosphere using a single metal, oxygen is deficient from the stoichiometric composition, whereas Comparative Example 1 This coating layer is a SiO ₂ film, that is, a silicon oxide film having a stoichiometric composition as described in JP-A-2011-1259.
Moreover, the comparative example 2 differs from Example 2 by the presence or absence of an intermediate layer.
The coating layer of Comparative Example 3 is a yttrium oxide film having a stoichiometric composition, that is, a Y ₂ O ₃ film, as will be described in detail later.
In Examples 1 to 6, it was confirmed from the results of observation with an optical microscope or the like that there was no significant decrease in the film thickness of the coating layer or disappearance of the film before and after pressing. From this result, it can be confirmed that the intermediate layers of Examples 1 to 6 satisfy the relationship of T1> T2.
As shown in Table 2, since Examples 1 to 6 were superior to Comparative Examples 1 to 3 in appearance evaluation evaluation results, metal oxide films in a state where oxygen was deficient from the stoichiometric composition were obtained. It can be confirmed that by providing the oxide glass through an intermediate layer satisfying T1> T2, it is possible to suppress the generation of bubbles in the glass during press molding.

3. Confirmation of the gas composition in the foam When the gas composition in the foam in the lens produced in Comparative Example 1 was analyzed by mass spectrometry, the press molding was performed in a nitrogen gas atmosphere. Over 10% oxygen was detected. This result confirms that the oxygen derived from the oxide glass is the cause of the generation of bubbles, as described above.
In Comparative Example 1, the coating layer is a SiO ₂ film having a stoichiometric composition. Since such a metal oxide film is chemically stable, it is considered that oxygen derived from oxide glass cannot be taken into the film during press molding. As a result, it is assumed that foaming is caused in the glass.

4). Analysis by TOF-SIMS (1)
About the glass material for press molding and the optical element produced under the same conditions as in Example 1, the surface was analyzed by TOF-SIMS (Time-of-flight secondary ion mass spectrometer) by the following method. The composition analysis in the depth direction was performed.
Depth direction analysis by TOF-SIMS Depth direction measurement was performed using TOF-SIMS300 manufactured by ION-TOF. TOF-SIMS is a technique for irradiating pulsed primary ions and detecting the generated secondary ions. In the depth direction analysis of TOF-SIMS, (i) irradiation with primary ions, (ii) measurement of secondary ions generated, (iii) irradiation with sputtered ions, and data obtained by repeating steps (i) to (iii) below. get.
Bi ₃ ⁺⁺ was used as the primary ion source, and the voltage applied to the column of the primary ion source was 25 kV. The measurement was performed with the primary ion source current set to 0.2 pA. The irradiation area of the primary ion source (= measurement region for detecting secondary ions) was 100 μm square, and negative ions were detected as secondary ions.
Cs was used for the sputter ion source. The acceleration of the sputter ion source was adjusted to 1 kV and the current value was adjusted to 75.4 nA. Sputtering was performed with a sputter ion source area of 400 μm square.

FIG. 4 is a diagram showing the depth direction analysis result of secondary ionic strength by TOF-SIMS before press molding (glass material for press molding) in Example 1.
The film thickness of the zirconium oxide film formed as the coating layer on the oxide glass in Example 1 and the ZrO ₂ film formed as the intermediate layer are both about 5 nm. FIG. 4 shows ZrO ₂ and simple Zr (“Zr” in FIG. 4) as secondary ions derived from the zirconium oxide film and the ZrO ₂ film. Although omitted in FIG. 4, ZrO derived from the zirconium oxide film and the ZrO ₂ film is also detected. Since Zr ₂ is not detected, the single Zr is not derived from the metal Zr but is considered to be derived from the zirconium oxide film and the ZrO ₂ film.
In FIG. 4, there are peaks in the ZrO ₂ spectrum in the region from the surface (depth 0 nm) to the depth of about 5 nm and from the depth of about 5 nm to about 10 nm, and in the region after the depth of about 10 nm. Since WO ₃ derived from the oxide glass is detected, it can be confirmed that two layers of an intermediate layer provided on the oxide glass and a coating layer provided on the intermediate layer are formed.
In the depth direction analysis result of secondary ion intensity by TOF-SIMS after press molding (optical element), in the region from the surface (depth 0 nm) to the depth of about 10 nm, the ZrO ₂ concentration is higher than the region after the depth of about 10 nm. WO ₃ was detected in a region where the peak intensity was high and the depth was about 10 nm or more. From this result, it can be confirmed that the coating layer is present on the oxide glass without causing a large decrease in film thickness or disappearance of the film even after press molding. From this result, it can also be confirmed that the intermediate layer satisfies the relationship of T1> T2.

From the results of depth direction analysis of secondary ion intensity by TOF-SIMS before press molding (glass material for press molding) and after press molding (optical element) in Example 1, the secondary ion intensity ratio of ZrO ₂ / Zr ( Hereinafter, it is described as “ZrO ₂ / Zr intensity ratio”. The ZrO ₂ / Zr intensity ratio is an index indicating the degree of oxidation in the zirconium oxide film. If zirconium oxide is in the state of oxygen than the stoichiometric composition is deficient, stoichiometric composition, i.e. from ZrO _2, ZrO ₂ / Zr intensity ratio becomes smaller.
From the result obtained for the press molding (glass material for press molding), it was confirmed that the ZrO ₂ / Zr strength ratio was smaller in the region corresponding to the coating layer than in the case of ZrO ₂ . From this result, it can be confirmed that the zirconium oxide film which is the coating layer of the glass material for press molding of Example 1 is in a state where oxygen is deficient from the stoichiometric composition.
Further, it was confirmed that the ZrO ₂ / Zr strength ratio was larger after press molding than before press molding in the region corresponding to the coating layer. That is, it was confirmed that the oxygen content of the coating layer increased after press molding. The present inventors consider that this result indicates that the coating layer has taken in oxygen from the oxide glass.

5. Analysis by TOF-SIMS (2)
Regarding the glass material for press molding and the optical element produced under the same conditions as in Example 2 and Comparative Example 3, the above 4. In the same manner as above, composition analysis in the depth direction from the surface was performed by TOF-SIMS.

FIG. 5 is a diagram showing the depth direction analysis results of secondary ion intensity by TOF-SIMS before press molding (glass material for press molding) in Example 2.
The film thickness of the yttrium oxide film formed as the coating layer on the oxide glass in Example 2 and the ZrO ₂ film formed as the intermediate layer are both about 5 nm. FIG. 5 shows YO ₂ and YO as secondary ions derived from the yttrium oxide film. Although not shown in FIG. 5, a single Y is also slightly detected. On the other hand, since Y ₂ is not detected, it is considered that the single Y does not originate from the metal Y but originates from the yttrium oxide film.
In FIG. 5, YO ₂ and YO spectral peaks are present in the surface (depth 0 nm) to about 5 nm depth, and ZrO ₂ spectra are present in the depth range of about 5 nm to about 10 nm. In addition, since WO ₃ derived from the oxide glass is detected in a region having a depth of about 10 nm or more, the intermediate layer (ZrO ₂ film) provided on the oxide glass and the intermediate layer are provided. It can be confirmed that two layers of the coating layer (yttrium oxide film) are formed.
Even in the depth direction analysis result of secondary ion intensity by TOF-SIMS after press molding (optical element), there are peaks of the spectrum of YO ₂ and YO in the region from the surface (depth 0 nm) to the depth of about 5 nm, A peak exists in the spectrum of ZrO ₂ in the region having a depth of about 5 nm to about 10 nm, and WO ₃ derived from the oxide glass was detected in a region having a depth of about 10 nm or more. From this result, it can be confirmed that the coating layer is present on the oxide glass without causing a large decrease in film thickness or disappearance of the film even after press molding. From this result, it can also be confirmed that the intermediate layer satisfies the relationship of T1> T2.

Regarding Example 2 and Comparative Example 3, from the results of depth direction analysis of secondary ionic strength by TOF-SIMS before press molding (glass material for press molding) and after press molding (optical element), before press molding and press molding. Secondary ion intensity ratio of YO ₂ / YO at positions 2.5 nm, 3.0 nm, 3.5 nm, and 4.0 nm deep from the subsequent surface (hereinafter referred to as “YO ₂ / YO intensity ratio”) Asked. The results obtained for Example 2 are shown in Table 3, and the results obtained for Comparative Example 3 are shown in Table 4.

The YO ₂ / YO intensity ratio is an index indicating the degree of oxidation in the yttrium oxide film. If the yttrium oxide is in a state where oxygen is deficient from the stoichiometric composition, the YO ₂ / YO intensity ratio becomes smaller than the stoichiometric composition, that is, Y ₂ O ₃ . From the YO ₂ / YO intensity ratios shown in Tables 3 and 4, the following points can be confirmed.
Table 4 YO ₂ / YO intensity ratio at each position of the covering layer of Comparative Example 3 before press-forming showing the yttrium oxide of stoichiometric composition, i.e., the same as the YO ₂ / YO intensity ratio of Y ₂ O ₃ is there. From this result, it can be confirmed that the coating layer of Comparative Example 3 is a yttrium oxide film having a stoichiometric composition, that is, a Y ₂ O ₃ film.
In contrast, YO ₂ / YO strength of YO ₂ / YO intensity ratio at each position of the covering layer of Example 2 before press-forming as shown in Table 3, the yttrium oxide of stoichiometric composition (Y ₂ O ₃₎ Small compared to the ratio. From this result, it can be confirmed that the yttrium oxide film, which is the coating layer of the press-molding glass material of Example 2, is in a state in which oxygen is lost from the stoichiometric composition.
Moreover, as shown in Table 3, in the coating layer of Example 2, the YO ₂ / YO strength ratio is larger after press molding than before press molding at each position. That is, it was confirmed that the oxygen content of the coating layer increased after press molding. The present inventors consider that the result shows that the coating layer has taken in oxygen from the oxide glass. However, the YO ₂ / YO intensity ratio at each position after press molding of the coating layer of Example 2 is smaller than the YO ₂ / YO intensity ratio of yttrium oxide (Y ₂ O ₃ ) having a stoichiometric composition. From this result, even after press molding, it can be confirmed that the coating layer of Example 2 is in a state where oxygen is lost from the stoichiometric composition.
On the other hand, as shown in Table 4, in the coating layer of Comparative Example 3, no significant difference in the YO ₂ / YO strength ratio was observed before and after press molding at each position. The coating layer of the glass material for press molding of Comparative Example 3 is a Y ₂ O ₃ film having a stoichiometric composition as described above. Since such a metal oxide film is chemically stable, it is considered that oxygen derived from oxide glass cannot be taken into the film during press molding. This is presumed to be the reason why a significant difference in the YO ₂ / YO strength ratio was not observed before and after press forming as shown in Table 4.

In the examples, a metal oxide film, specifically a zirconium oxide film, was formed as the intermediate layer. However, the intermediate layer only needs to satisfy the relationship of T1> T2, and is limited to the embodiment shown in the examples. is not.

Finally, the above aspects will be summarized.

According to one aspect,
Oxide glass,
A coating layer that is a metal oxide film that covers at least a part of the surface of the oxide glass and in which oxygen is lost from the stoichiometric composition;
An intermediate layer provided between the oxide glass and the coating layer;
With
In the intermediate layer, the rate of diffusion of oxygen atoms contained in the oxide glass at a temperature equal to or higher than the glass transition temperature of the oxide glass is greater than the rate of diffusion of metal atoms contained in the metal oxide film at the temperature. Fast, glass optics,
Is provided.

According to one aspect,
Oxide glass,
A coating layer that is a metal oxide film that covers at least a part of the surface of the oxide glass and in which oxygen is lost from the stoichiometric composition;
An intermediate layer provided between the oxide glass and the coating layer;
With
In the intermediate layer, the rate of diffusion of oxygen atoms contained in the oxide glass at a temperature equal to or higher than the glass transition temperature of the oxide glass is greater than the rate of diffusion of metal atoms contained in the metal oxide film at the temperature. Fast, glass material for press molding,
Is provided.

According to one aspect,
It has a pressing process to press-mold a glass material for press molding to form a press-molded body,
The method for producing a glass optical element, wherein the glass material for press molding is the glass material for press molding described above,
Is provided.

According to the method for producing an optical element using the above-described glass material for press molding, it is possible to provide a homogeneous optical element in which the generation of bubbles is suppressed.

In one aspect,
A glass optical element obtained by the above production method,
Is provided.

In one aspect,
In the manufacturing method of the optical element,
The press-molded body includes the coating layer that has undergone the pressing step, and the coating layer that has undergone the pressing step is a metal oxide film having a higher oxygen content than the coating layer before the pressing step.

Furthermore, in one aspect, the metal oxide film included in the press-formed body is in a state where oxygen is deficient due to the stoichiometric composition.

Note that the press-molded body after press molding may be applied as it is to an imaging camera or the like as an optical element, or may be applied as an optical element after its end is removed by a centering process. In the latter case, part of the coating layer (metal oxide film) is removed by the centering step.

In one aspect, the above-mentioned oxide glass contains one or more high refractive index imparting components selected from the group consisting of Nb ₂ O ₅ , TiO ₂ , WO ₃ and Ta ₂ O ₅ . The total content (Nb ₂ O ₅ + TiO ₂ + WO ₃ + Ta ₂ O ₅ ) of the high refractive index imparting component is preferably 10% by mass or more and 50% by mass or less.

In one embodiment, the above oxide glass contains one or more selected from the group consisting of ZnO and alkali metal oxides (Li ₂ O, Na ₂ O, K ₂ O). Preferably, the total content of ZnO and alkali metal oxide (ZnO + Li ₂ O + Na ₂ O + K ₂ O) is 5% by mass or more and 25% by mass or less.

In one aspect, heating during press molding is performed at a heating temperature of 650 ° C. or higher. According to the method for manufacturing an optical element described above, the generation of bubbles in press molding at such a high temperature can be suppressed.

The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

The present invention is useful in the field of manufacturing optical elements such as glass lenses.

Claims (9)

1. Oxide glass,
   A coating layer that covers at least part of the surface of the oxide glass and is a metal oxide film in which oxygen is lost from the stoichiometric composition;
   An intermediate layer provided between the oxide glass and the coating layer;
   With
   In the intermediate layer, the rate of diffusion of oxygen atoms contained in the oxide glass at a temperature equal to or higher than the glass transition temperature of the oxide glass is greater than the rate of diffusion of metal atoms contained in the metal oxide film at the temperature. Fast, glass optical element.
2. The glass optical element according to claim 1, wherein the metal oxide is an oxide of a metal selected from the group consisting of zirconium, yttrium, tantalum, niobium, tungsten, and titanium.
3. The glass optical element according to claim 1, wherein the intermediate layer is a metal oxide film.
4. The glass optical element according to claim 3, wherein the intermediate layer is a zirconium oxide film.
5. Oxide glass,
   A coating layer that covers at least part of the surface of the oxide glass and is a metal oxide film in which oxygen is lost from the stoichiometric composition;
   An intermediate layer provided between the oxide glass and the coating layer;
   With
   In the intermediate layer, the rate of diffusion of oxygen atoms contained in the oxide glass at a temperature equal to or higher than the glass transition temperature of the oxide glass is greater than the rate of diffusion of metal atoms contained in the metal oxide film at the temperature. Fast, glass material for press molding.
6. The glass material for press molding according to claim 5, wherein the metal oxide is an oxide of a metal selected from the group consisting of zirconium, yttrium, tantalum, niobium, tungsten and titanium.
7. The press-molding glass material according to claim 5 or 6, wherein the intermediate layer is a metal oxide film.
8. The glass material for press molding according to claim 7, wherein the intermediate layer is a zirconium oxide film.
9. It has a pressing process to press-mold a glass material for press molding to form a press-molded body,
   A method for producing a glass optical element, wherein the glass material for press molding is the glass material for press molding according to any one of claims 5 to 8.

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