JPH08217466A - Molding method for glass optical element - Google Patents

Abstract

(57) [Abstract] [Purpose] Regardless of the type of glass molding material, it suppresses volatilization and diffusion of internal glass components to obtain a lens with a good appearance with no cloudiness on the surface, and also enables high temperature mold release. Therefore, the present invention provides a method for molding a glass optical element, which can shorten the molding cycle and can manufacture a lens having a good appearance at a lower cost. [Structure] A glass forming material having an oxide surface layer containing SiO _{2 as a} main component and further containing an alkali metal oxide, a mold having a film containing a carbon main component on the outermost surface of the forming surface, or containing an alkali metal element. A method for molding a glass optical element by press molding with a ceramic molding die.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a press molding method for glass optical elements such as lenses and prisms.

[0002]

2. Description of the Related Art In the past, in order to obtain a good molded product in press molding of a glass optical element, it has been a major problem to prevent fusion between a glass molding material and a molding die. Therefore, conventionally, a technique for improving a molding die has been proposed. To give some examples, JP-A-49-5
1112 is 13Cr martensitic steel, and
-45613 includes SiC and Si ₃ N ₄ , which are disclosed in
No. 246230 proposes a material in which a noble metal is formed on a cemented carbide.

Japanese Unexamined Patent Publication (Kokai) No. 61-136928 proposes a mold material in which a noble metal is formed on a composite material base material made of metal and ceramics through an intermediate layer of nitride, carbide, oxide and metal. Further, JP-A-60-81032 proposes mold materials of glassy carbon, silicon carbide, silicon nitride and sialon.

Further, in accordance with the recent progress of thin film technology, Japanese Patent Application Laid-Open No. 61-183134 proposes forming a diamond or diamond-like carbon film on a cemented carbide and forming it.

Further, in recent years, improvements in molding materials have begun to be proposed in order to prevent the fusion. As a proposal for improving such a molding material, for example, Japanese Patent Publication No. 2-
No. 1778, Japanese Patent Publication No. 2-1779, Japanese Patent Publication No. 2
No. 1780 and Japanese Patent Publication No. 61-29890 disclose that a glass substrate having a glass transition temperature higher than that of the glass substrate, a silicon oxide coating or a carbon coating is provided on the surface of the glass substrate. . Further, JP-A-1-264937 discloses disposing a thin layer of an organic substance on the surface of a glass substrate.

[0006]

However, the 13Cr martensitic steel disclosed in JP-A-49-51112 is excellent in workability, but is insufficient in scratch resistance, heat resistance and releasability. Therefore, it cannot be said that it is a good mold material. SiC and Si disclosed in JP-A-52-45613
₃ N ₄ is excellent in scratch resistance and heat resistance, but has problems in workability and mold releasability. Also, JP-A-60-81
Although the glassy carbon disclosed in 032 is excellent in mold releasability, it has problems in specularity and material strength.

As described above, when the mold material is a single material, the performance required as a glass molding die cannot be sufficiently satisfied, and as described in JP-A-60-246230, the mold base material is The mold-releasing property lacking in cemented carbide is compensated by the surface treatment of the noble metal mold, but it is necessary to improve it in terms of scratch resistance. Further, a diamond or diamond-like carbon film is formed on the cemented carbide disclosed in JP-A-61-183134 to try to improve scratch resistance without impairing releasability. There is a problem that the surface roughness is large and mirror polishing is required after film formation, and that mirror polishing is difficult.On the other hand, the diamond-like carbon film deteriorates due to volatilized reaction components from glass in the press molding process at high temperature. It had the drawback of being exhausted.

Further, in recent years, there are various kinds of glass materials to be press-molded, and there is a large difference in the reactivity and adhesion between the mold surface and the glass depending on the components of the glass materials, so the mold material and the press-molding method must be changed depending on the glass material. The inconvenience has occurred.

The first object of the present invention is to mold an appropriate alkali metal component which prevents the volatilization / diffusion of components deteriorating the mold molding surface from the glass molding material and at the same time reduces the adhesion between the mold and the glass. By supplying it to the interface between the surface and the glass and reducing the adhesion between the mold surface containing the carbon-based component and the glass to the extent that cannot be achieved with the carbon-based mold alone, high-temperature release during press molding can be achieved. is there.

A second object of the present invention is to prevent the mold forming surface from deteriorating due to the excessive volatilization of easily volatilized components of the glass forming material, and at the same time, to release the glass at a high temperature from the mold containing carbon as a main component. The purpose is to clarify the composition of the oxide surface layer of the molding material.

A third object of the present invention is to clarify the film thickness of the oxide surface layer of the glass molding material for obtaining a glass optical element which is free from surface cracks during press molding and has a good appearance.

A fourth object of the present invention is to clarify a molding surface material of a mold that can achieve high temperature mold release when press molding a glass molding material having an oxide surface layer containing an alkali metal. is there.

[0013]

Means for Solving the Problems The first invention is SiO
₍₂₎ A glass optical element characterized by press-molding a glass molding material having an oxide surface layer containing, as a main component, an alkali metal oxide, with a molding die having a film of a carbon main component on the outermost surface of the molding surface. Molding method. A second aspect of the present invention is characterized in that a glass molding material having an oxide surface layer containing SiO _{2 as a} main component and further containing an alkali metal oxide is press-molded with a ceramic molding die containing an alkali metal element. This is a method of molding an optical element. In these inventions, on the glass molding material surface,
While suppressing volatilization / diffusion of the components of the inner glass, a glass blank having an oxide surface layer containing an alkali metal oxide that can be released at high temperature from a mold containing carbon as a main component is press-molded to have a good appearance and Obtaining low cost glass optics.

The third invention is based on the first and second inventions.
The oxide surface layer of the glass molding material is SiO₂85
mol% or more, Li₂O, Na₂O and K₂1 type of O
2-10 mol% of the above alkali metal oxides,
Al as a component₂O₃And B ₂O₃Contains one or more of
This is the case. Table of molded products regardless of glass molding material
The surface does not cause optical defects such as cloudiness,
Adhesion is low and suitable for high temperature release press molding.
There is.

In a fourth aspect of the present invention according to the first and second aspects of the present invention, the film thickness of the oxide surface layer of the glass molding material is 10 to 5.
This is the case of 0 nm. The effect of suppressing volatilization / diffusion of the internal glass component of the oxide surface layer of the glass molding material is 10
The thickness of the oxide surface layer is suitable to be 10 nm to 50 nm, because the occurrence of surface layer cracks due to deformation during press molding depends on the amount of deformation and starts to be observed from around 50 nm. In addition, a thin film of this degree has a significantly small effect on the optical characteristics of a lens or the like.

A fifth aspect of the present invention is the same as the first aspect of the present invention.
This is the case where the carbon-based film is made of glassy carbon, graphite, hydrogenated amorphous carbon, or diamond. The glass blank having an oxide surface layer containing an alkali metal oxide has a good appearance and is particularly suitable for press molding at high temperature release.

The sixth aspect of the present invention is the same as the second aspect of the present invention.
This is a case where the ceramic molding die containing an alkali metal element has a nitride film on the outermost surface of the molding surface, and the nitride film is ion-implanted with one or more kinds of Li, Na and K. A hard nitride film containing about several percent of Li, Na, and K is particularly suitable for press molding of a glass blank having an alkali metal oxide-containing oxide surface layer with good appearance and high temperature release.

[0018]

【Example】

(Embodiment 1) FIG. 1 schematically shows an apparatus for carrying out the molding method of the present invention, in which 1 is a molding chamber,
2 is a preheating heater for preheating the glass material,
3 is a transport shaft, 4 is a glass holder, and 5 is a glass material. The preheating heater 2 has a shape suitable for intensively heating the glass material and is attached at an appropriate position. The glass holder 4 has a high density charcoal to prevent fusion with high temperature glass. It uses materials. 6 is a cylinder, 7 is an upper shaft, 8 is a cylinder, 9 is a lower shaft, 10
Is an upper mold, 11 is a lower mold, 12 is a barrel mold, 13 is a heater, 1
Reference numeral 4 is a transport shaft, and 15 is a suction jig.

FIG. 2 is a schematic view of a glass blank for molding used in the present invention, in which 60 is a glass material for molding and 61 is a glass material for molding.
Is an oxide surface layer, and 65 is a molding glass blank having an oxide surface layer.

FIG. 3 is a schematic view of a molding die used in the present invention. In the figure, 70 is a mold base material, 71 is a metal film, 72 is a hard compound film, 73 is a carbon-based release film, and 75 is a release film. A mold having a release film.

Oxide surface on glass material before press molding
A layer formation process is shown. Glass material with a predetermined shape (SK12)
After cleaning 60, SiO (not shown)₂ 90 mol%,
Al ₂O₃ 5 mol%, Na₂Composition of O 5 mol%
Sputtering equipment equipped with a sputtering target
Set it in the film equipment and sputter gas Ar at 15 sccm.
Flow rate, reaction gas O₂Flow rate of 5 sccm
Radio frequency (RF) electric power of 0.
The oxide surface layer 61 is formed by forming a film at 5 kW for 3 minutes.
A shape glass blank 65 was manufactured.

On the other hand, the upper and lower molds for molding are processed into a predetermined mold shape from a binderless cemented carbide (TJ05: made by Fuji Die) to form a mold base material 70, and a metal film 71 is formed on the molding surface by vapor deposition or sputtering. Furthermore, hard nitrides (TiN, TaN, HfN, etc.) or hard carbides (Tn) are formed by reactive ion plating or reactive sputtering.
iC, TaC, HfC, SiC, etc.) film 72 is formed to a thickness of about 2 μm, and a hydrogenated amorphous carbon film 73 of 0.1 μm is formed thereon by an ion beam deposition method using CH ₄ and H ₂ gas as precursors.
m to form a molding die 75.

Examples of press molding will be shown below. Glass material (SK12) 5 with a predetermined shape that is a lens molding material
Is transferred into the molding chamber 1 kept in the N ₂ atmosphere by the glass holder 4 via the transfer shaft 3 via the replacement chamber (not shown), and stopped at the heating point immediately below the preheating heater 2, After energizing the preheating heater 2 to preheat the glass material 5, the glass holder 4 is moved and placed on the lower mold 11 (molding mold 75). Next, the heater 13
After heating the barrel mold 12 to 630 ° C. by increasing the energizing power of the mold, lowering the upper mold 10 (molding mold 75) to perform press molding at a predetermined pressure, and then cooling the mold to 550 ° C. (Tg). The upper mold 10 is raised, the molded lens is sucked by the suction jig 15, and the upper lens 10 is taken out via a replacement chamber (not shown). A lens was manufactured by continuous molding in which the above press molding process is repeated.

The temperature at which the upper mold 10 is raised (cooling temperature) during cooling after press molding (mold release temperature) needs to be equal to or lower than the glass Tg in order not to reduce the surface transfer shape (surface accuracy) of the molded lens. In order to shorten the molding takt time and improve the productivity, it is required that the mold release temperature be as high as possible within the range. A molding method using a mold having a film of a carbon main component of a glass blank having an oxide surface layer containing an alkali metal oxide on the outermost surface of the molding surface is T
The mold can be released stably even at a high temperature around g, and the inconvenience such as adhesion of the molded lens to the mold does not occur.
Since a lens with a good appearance can be manufactured in a short cycle time, cost reduction can be realized.

Next, the alkali metal oxide content of the sputtering target was variously changed to prepare glass blanks for molding on which oxide surface layers having different alkali metal oxide content were formed. As a result of molding these glass blanks, as shown in Tables 1 to 3, the releasing effect becomes remarkable when the content of the alkali metal oxide in the oxide surface layer is 2 mol% or more, but exceeds 10 mol%. It was found that this is not preferable because the generation of cloudiness on the surface of the molded lens causes a remarkable decrease in transmittance and deterioration of the carbon layer on the molding surface, which deteriorates optical performance and appearance performance.

[0026]

[0027]

[0028]

The film thickness of the oxide surface layer of the glass material affects the adhesion between the mold and the glass and the appearance of the lens as well as the film composition. It does not largely depend on the kind of the alkali metal element contained in the film, and when the film thickness is less than 10 nm, the cloudiness is not observed in the central part of the lens with respect to the oxide surface layer having the composition shown in Tables 1 to 3. It easily occurs, and if it exceeds 50 nm, surface layer cracks easily occur in the peripheral portion of the lens, so that there is a problem in optical performance and appearance performance as a lens. Further, even if the film thickness is so large that surface layer cracks do not occur, it is necessary to particularly consider and study the film structure of the antireflection film in the subsequent step.

(Example 2) As in Example 1, a glass blank 65 for molding was produced in which an oxide surface layer 61 was formed on a glass material 60. On the other hand, the upper and lower molds for molding are formed on the molding surface of the mold base material 80 made of sintered SiC by CVD as shown in FIG.
After forming SiC, a mold release film 82 of amorphous carbon was formed on the mirror-polished layer 81 by RF sputtering with Ar gas using a carbon target to form a mold 85.

Using the molding glass blank 65 and the molding die 85, continuous molding was carried out by the same molding method as in Example 1.

The releasability and the lens appearance performance were the same as those in Example 1.

(Embodiment 3) A glass blank 65 for molding having an oxide surface layer 61 formed on a glass material 60 was manufactured in the same manner as in Embodiment 1. On the other hand, as shown in FIG. 5, the upper and lower molds for molding are made into a mold base material 90 by processing a binderless cemented carbide (TJ05: made by Fuji Die) into a predetermined mold shape, and a metal film is formed on the molding surface by vapor deposition or sputtering. 91, and hard nitrides (TiN, TaN, HfN, etc.) by reactive ion plating or reactive sputtering
A film 92 having a thickness of about 2 μm is formed, and an alkali metal element (L
i, Na, K) 1 x 10 ¹⁷ ions / c
A layer 93 in which m ² ions were implanted was formed to form a molding die 95.

Using the molding glass blank 65 and the molding die 95, continuous molding was carried out by the same molding method as in Example 1.

The releasability and the lens appearance performance were the same as those in Example 1.

[0036]

As described above, according to the first aspect of the present invention, a glass molding material having an oxide surface layer containing SiO _{2 as a} main component and further containing an alkali metal oxide is used as a carbon-based film. By press-molding with the molding die at the outermost surface of the molding surface, regardless of the type of glass molding material, it is possible to obtain a lens with good appearance without clouding on the surface by suppressing volatilization and diffusion of internal glass components. Since high temperature mold release is possible, the molding cycle can be shortened. As a result, a lens having a good appearance can be manufactured at a lower cost.

According to the second aspect of the present invention, a glass molding material having an oxide surface layer containing SiO _{2 as a} main component and further containing an alkali metal oxide is press-molded with a ceramic molding die containing an alkali metal element. As a result, the same effect as that of the first aspect of the present invention was obtained.

According to the third invention, 85 mol% or more of SiO ₂ and Li ₂ are added to the oxide surface layer of the glass molding material.
₂ to 10 mol% of one or more alkali metal oxides of O, Na ₂ O and K ₂ O, and Al ₂ O ₃ as the remaining component
By containing at least one of B ₂ O ₃ and B ₂ O ₃ , volatilization and diffusion of the internal glass (glass forming material) of the glass blank for molding is suppressed during press molding, and a lens with a good appearance with no cloudiness on the surface can be obtained. Moreover, since high temperature mold release is possible, the molding cycle can be shortened. Further, when the composition of the glass molding material is inferior in environmental resistance, the environmental resistance can be improved. That is, since the film of the composition of the present invention covers the lens surface, improvement in durability was recognized in the evaluation of the constant temperature and constant humidity environment test.

According to the fourth aspect of the present invention, by setting the thickness of the oxide surface layer of the glass molding material to 10 to 50 nm, there is no cloud on the surface of the molded lens and there is no surface crack due to deformation. Good lens press molding has become possible. Further, since the film thickness is an extremely thin film of about 10 to 50 nm, practical optical performance could be obtained without changing the structure of the antireflection film of the lens.

According to the fifth aspect of the present invention, a glass molding material having an oxide surface layer containing SiO _{2 as a} main component and further containing an alkali metal oxide is used as a film containing carbon as a main component of glassy carbon or graphite or a non-hydrogenated film. By molding with a mold made of crystalline carbon or diamond, high-temperature mold release, which has not been obtained in the past, was possible, the mold was not deteriorated even in continuous molding, and the molded lens was able to maintain a good appearance performance. Practically, the lens cost can be reduced by shortening the molding cycle and reducing the mold recycling cost.

According to the sixth aspect of the present invention, a glass molding material having an oxide surface layer containing SiO _{2 as a} main component and further containing an alkali metal oxide is molded into a ceramic molding die containing an alkali metal element. The same effect as the fifth aspect of the present invention was obtained by forming a nitride film on the outermost surface of the surface and molding the nitride film with a mold in which one or more kinds of Li, Na and K were ion-implanted. .

[Brief description of drawings]

FIG. 1 is a press molding apparatus according to a first embodiment.

FIG. 2 is a glass blank for molding according to Example 1.

FIG. 3 is a molding die according to Example 1.

FIG. 4 is a molding die according to a second embodiment.

5 is a molding die according to Example 3. FIG.

[Explanation of symbols]

 1 Molding Chamber 2 Preheating Heater 3 Conveyor Shaft 4 Glass Holder 5 Glass Material 6 Cylinder 7 Upper Shaft 8 Cylinder 9 Lower Shaft 10 Upper Mold 11 Lower Mold 12 Body Mold 13 Heater 14 Conveyor Shaft 15 Adsorption Jig 60 Molding Glass Material 61 Surface coating layer 65 Molding glass blank 70 Type base material 71 Metal film 72 Hard compound film 73 Carbon-based release film 75 Molding die 80 Molding base material 81 CVD SiC film 82 Sputtered carbon film 85 Molding die 90 Molding base material 91 Metal film 92 Hard compound film 93 Alkali metal layer 95 Mold

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Nao Miyazaki 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc.

Claims (6)

[Claims] 1. A glass molding material having an oxide surface layer containing SiO _{2 as a} main component and further containing an alkali metal oxide,
A method of molding a glass optical element, comprising press-molding with a molding die having a film containing a carbon main component on the outermost surface of the molding surface. _2. A glass molding material having an oxide surface layer containing SiO _{2 as a} main component and further containing an alkali metal oxide,
A method of molding a glass optical element, which comprises press-molding with a ceramic molding die containing an alkali metal element. 3. The oxide surface layer of the glass molding material is Si
85 mol% or more of O ₂ , Li ₂ O, Na ₂ O and K ₂
2-10 mol of one or more alkali metal oxides of O
%, And at least one of Al ₂ O ₃ and B ₂ O ₃ as the remaining components. 4. The method for molding a glass optical element according to claim 1, wherein the film thickness of the oxide surface layer of the glass molding material is 10 to 50 nm. 5. The method for molding a glass optical element according to claim 1, wherein the film containing carbon as a main component is made of glassy carbon, graphite, hydrogenated amorphous carbon or diamond. 6. A ceramic molding die containing an alkali metal element, having a nitride film on the outermost surface of the molding surface, and ion-implanting at least one kind of Li, Na and K into the nitride film. The method for molding a glass optical element according to claim 2, wherein