JP2013203567A - Mold for molding optical element, method of manufacturing optical element, and method of manufacturing mold for molding optical element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a mold for molding an optical element and a method of manufacturing the mold for molding the optical element such that even when a noble metal film is used as a release film, durability of the release film can be improved.SOLUTION: A lower mold 2 includes a base material 2A which has a base material surface Sin a shape conforming to a surface shape of a molding and is made of silicon carbide, a plurality of carbon nanotubes 10 extending from the base material surface S, an intermediate metal layer 2B made of metal 11 deposited on the base material 2A while fitting the gap among the carbon nanotubes 10, and a release film 2C laminated on the intermediate metal layer 2B.

Description

  The present invention relates to an optical element molding die, an optical element manufacturing method, and an optical element molding die manufacturing method. For example, the present invention relates to an optical element molding die for molding an optical element by heating and pressing a molding material made of glass, an optical element manufacturing method, and an optical element molding die manufacturing method.

Conventionally, as a mold for molding glass, a cemented carbide is used as a mold base, and a mold release film is provided on the molding surface of the mold base to facilitate release of the glass after molding. It has become. As the release film, a single layer or a plurality of layers of thin films made of noble metal, noble metal alloy, carbon or the like is used.
On the other hand, a glass-molded lens molded by such a molding die has been used with a glass material having a high refractive index in order to reduce the size by increasing the refractive power. Such a high refractive index glass material has a higher molding temperature than a low refractive index glass material.
For this reason, it has been proposed to use silicon carbide that can withstand molding at higher temperatures as the base of the mold. However, when using silicon carbide as a base material and using a noble metal release film, the adhesion between the base material and the release film is low, so the release film peels off from the base material during molding. was there.
As a technique for improving the adhesion between the base material of the mold and the release film, Patent Document 1 discloses that the base material is a cemented carbide and the release film is a carbon film. An intermediate layer film such as chromium (Cr) or tantalum (Ta) having high adhesion is provided on both the base material and the release film between the material and the release film, and a gas cluster ion beam is provided on the intermediate layer film. A technique for forming a carbon film under assisting irradiation has been proposed.

JP 2005-169816 A

However, the conventional optical element molding die as described above has the following problems.
When an intermediate layer film such as chromium (Cr) or tantalum (Ta) is provided between the mold base and the release film as in the technique described in Patent Document 1, the release film is made of a noble metal-based release film. There is a problem that good durability cannot be obtained with a mold membrane.
First, by repeating the glass forming, the intermediate layer film component diffuses into the noble metal layer, which is the release film, and the composition of the release film is changed.
Further, there is a problem that the intermediate layer film is consumed and the adhesion is lost due to the diffusion of the intermediate layer component into the release film.
Since such diffusion of the intermediate layer film component is more likely to occur as the molding temperature increases, the durability of the release film decreases particularly when the molding temperature must be increased, such as when molding a high refractive index glass. There is a problem of end up.

  The present invention has been made in view of the above problems, and can be used to mold an optical element that can improve the durability of a release film even when a noble metal film is used as the release film. It is an object of the present invention to provide a method for manufacturing a mold and an optical element molding mold.

  In order to solve the above-described problems, an optical element molding die of the present invention has a surface having a shape that conforms to the surface shape of a molded product, and includes a base portion made of silicon carbide and a plurality of carbons extending from the surface. The structure includes a nanotube, an intermediate metal layer made of metal buried between the carbon nanotubes and deposited on the base member, and a release film laminated on the intermediate metal layer.

  In the optical element molding die of the present invention, the metal may be made of one or more of titanium, zirconium, and molybdenum.

  In the optical element molding die of the present invention, the carbide of the metal can be formed between the intermediate metal layer and the carbon nanotube.

  In the optical element molding die of the present invention, the release film includes a lowermost layer laminated on the intermediate metal layer, and an outermost layer having a molding surface that is in close contact with the material of the molded product so as to be releasable. , At least a multilayer film.

  In the optical element molding die of the present invention, the metal may be a metal used for the release film.

  The method for producing an optical element of the present invention is a method for obtaining the molded product by molding the material of the molded product using the mold for molding an optical element molding of the present invention.

The method for producing an optical element molding die of the present invention includes a base material portion forming step of forming a base material portion made of silicon carbide so as to have a surface having a shape that conforms to the surface shape of a molded product,
Heat treating the base material portion to volatilize the silicon component on the surface and form a plurality of carbon nanotubes extending from the surface of the base material portion; and a metal between the carbon nanotubes. A method comprising: an intermediate metal layer forming step of filling and depositing on the base material portion to form an intermediate metal layer; and a release film forming step of forming a release film on the intermediate metal layer; To do.

  The method for producing an optical element of the present invention includes a method for obtaining a molded product by molding the material of the molded product using the optical element molding die obtained by the method for producing an optical element molding die of the present invention. To do.

  According to the optical element molding die and the method of manufacturing an optical element molding die of the present invention, the base material portion and the release film are embedded in the carbon nanotubes, with the plurality of carbon nanotubes extending from the surface of the base material portion. Since it is laminated via the intermediate metal layer made of the metal, the durability of the release film can be improved even when a noble metal film is used as the release film.

It is typical sectional drawing which shows an example of the optical element shaping | molding die of embodiment of this invention. It is a typical fragmentary enlarged view of the A (B) part in FIG. It is a typical fragmentary sectional view which shows an example of the film | membrane structure of the release film used for the optical element shaping | molding die of embodiment of this invention. It is a flowchart which shows the process flow of the manufacturing method of the optical element shaping | molding die of embodiment of this invention. It is typical process explanatory drawing of the manufacturing method of the optical element shaping | molding die of embodiment of this invention. It is typical process explanatory drawing explaining the intermediate metal layer formation process of the manufacturing method of the optical element shaping | molding die of embodiment of this invention.

Embodiments of the present invention will be described below with reference to the accompanying drawings.
First, an optical element molding die according to an embodiment of the present invention will be described.
FIG. 1 is a schematic cross-sectional view showing an example of an optical element molding die according to an embodiment of the present invention. FIG. 2 is a schematic partial enlarged view of an A (B) portion in FIG. FIG. 3 is a schematic partial cross-sectional view showing an example of a film configuration of a release film used in the optical element molding die according to the embodiment of the present invention.

The optical element molding die according to the present embodiment constitutes a part of a mold assembly for manufacturing a glass optical element such as a lens by pressing a glass material that is a molding material. A molding surface for transferring the shape of the optical surface to the glass material is provided.
The type of the optical element is not particularly limited as long as it is made of glass. For example, an appropriate type such as a lens, a prism, a mirror, a filter, or a substrate can be adopted. When the optical element has a curvature, it may be convex or concave.
Hereinafter, as an example of an optical element, an example in the case of molding a meniscus lens (not shown) having a convex lens surface and a concave lens surface will be described.

A mold assembly 1 for molding the lens includes a lower mold 2 (optical element molding mold), an upper mold 3 (optical element molding mold), and a body mold 4 as shown in FIG.
The lower die 2 is a substantially columnar member having a cylindrical side surface 2b. A flange portion 2c protruding from the side surface 2b in the outer peripheral direction is formed at one axial end portion (lower side in FIG. 1). A molding surface 2a having a concave shape that transfers the shape of the convex lens surface to the glass material is formed at the other end (upper side in FIG. 1).

The side surface 2b and the flange portion 2c are formed by the surface of a base material 2A (base material portion) made of a material having high hardness and good heat resistance.
As the material of the substrate 2A, a sintered body of silicon carbide (SiC) is employed.

As shown in FIG. 2, on the other end side in the axial direction of the base material 2A, the intermediate metal layer 2B and the base metal surface S _2A (surface of the base material part), which is a concave surface along the shape of the molding surface 2a, The release film 2C is laminated in this order. The outermost surface of the release film 2C constitutes a molding surface 2a.

On the substrate surface S _2A, in order to firmly adhere the intermediate metal layer 2B on the substrate surface S _2A, a plurality of carbon nanotubes 10 that extends from the substrate surface S _2A to release film 2C is provided Yes.
Carbon nanotubes 10, on the substrate surface S _2A, and densely in a state spaced dense or small gap, which protrudes substantially perpendicular to the substrate surface S _2A.
Further, the density of the carbon nanotubes 10 is substantially uniform over the entire substrate surface _S2A .
The diameter of each carbon nanotube 10 can be, for example, about 1 nm to 15 nm. The length of each carbon nanotube 10 can be, for example, an appropriate length of about 10 μm or less, and has a substantially uniform length so as to obtain a necessary adhesion strength to the intermediate metal layer 2B described later. .
Therefore, the carbon nanotubes 10, on the substrate surface S _2A, are formed in raised state in layers range of substantially constant height.
The carbon nanotube 10 has high strength due to carbon bonds. The carbon nanotube 10 is also chemically bonded to the substrate 2A on the substrate surface _S2A .

Such a carbon nanotube 10 is covered with an intermediate metal layer 2B made of a metal 11 having good adhesion strength with respect to each of the carbon nanotube 10 and the release film 2C.
That is, the intermediate metal layer 2 </ b> B includes a metal embedded layer L _{1 in} which the metal 11 is embedded between the carbon nanotubes 10 and the metal 11 only in the layered range of the carbon nanotubes 10, and covers the metal embedded layer L ₁ . are stacked so consists coating layer L ₂ Metropolitan constituting the outermost surface S _2B of the release film 2C side of the intermediate metal layer 2B.
Since the metal 11 is embedded in a minute gap between the carbon nanotubes 10, the metal embedding layer L ₁ meshes with the carbon nanotubes 10 in a comb shape.

As the type of the metal 11, the adhesion with the release film 2 </ b> C from one or more of metals having good adhesion with carbon, for example, titanium (Ti), zirconium (Zr), molybdenum (Mo), etc. Those having good strength can be employed.
Further, the metal 11 is more preferably a material that easily forms carbides, because it can form carbides on the surface of the carbon nanotubes 10 and can be firmly bonded by chemical bonding. Further, it is more preferable that the metal 11 has good adhesion strength with the material of the base material 2A.
When the release film 2 </ b> C is a metal-based release film, Ti that has good adhesion strength to many metals is particularly suitable as the metal 11.
When Ti is embedded between the carbon nanotubes 10 by, for example, chemical vapor deposition (CVD) or the like, a carbide is formed on the surface of the carbon nanotubes 10 and chemically bonded, so in the metal embedded layer L ₁ Adhesive strength with the carbon nanotube 10 becomes good.
The metal 11 is preferably a metal used for the release film 2C because the adhesion strength with the release film 2C is improved. That is, when the release film 2C is made of a noble metal, a material excellent in adhesion to carbon among the noble metals used for the release film 2C can be suitably used.
When the metal 11 is a metal used for the release film 2C, even if the metal 11 diffuses into the release film 2C, the change in the composition of the release film 2C is reduced. It becomes easy to suppress a decrease in releasability due to.

Coating layer L ₂ is provided to improve the adhesion strength between the parting layer 2C. Therefore, it is possible as long as it can cover the top portion of the carbon nanotubes 10 in the metal buried layer L _1, it is formed into a thin layer compared to the layer thickness of the metal buried layer L _1.
The widely used noble metal release film 2 </ b> C has excellent adhesion strength to metal and low adhesion strength to the carbon nanotube 10. For this reason, if there are many portions where the surface of the carbon nanotube 10 is exposed, the area contributing to the adhesion strength is reduced, and the adhesion strength of the release film 2C is reduced.
By providing the coating layer L _2, since the area of the adherable metal 11 of the release film 2C increases, it is possible to improve the adhesion between the release film 2C.
The metal 11 in close contact with the surface of the carbon nanotubes 10, because they do not readily diffuse, by thinning the cover layer L _2, the metal 11 to be diffused relatively release film 2C in the coating layer L ₂ is reduced . Even if some of the metals 11 diffuse, the absolute amount of diffusion decreases. For this reason, it becomes easy to suppress the deterioration of releasability due to diffusion of the metal 11 into the release film 2C.

As long as the outermost part of the release film 2C is a material having good releasability from the glass material used for molding, an appropriate layer structure of an appropriate material can be adopted. The layer configuration may be, for example, a single layer configuration or a multilayer configuration.
In general, when the substrate is made of a cemented carbide whose main component is tungsten carbide (WC), the structure of the release film suitable for the sintered body of SiC does not have good adhesion strength. In the embodiment, since the intermediate metal layer 2B is formed between the base material 2A, a release film in the case of using such a cemented carbide as the base material is also suitable.
Further, the release film 2C is not limited to the cemented carbide release film as long as the adhesion strength to the metal 11 is good, and other known release films are also suitable.
In the present embodiment, a film configuration suitable for such a cemented carbide is employed as an example of the release film 2C.
That is, as shown in FIG. 3, the film configuration of the release film 2C is as follows: from the intermediate metal layer 2B side, the base layer 5 (lowermost layer), the metal layer 6, the nitride layer 7, and the surface layer 8 (outermost layer). Are stacked in this order.
As a method for forming the release film 2C, for example, an evaporation method, a sputtering method, a CVD method, or the like can be used, but an ion beam sputtering method is particularly preferable from the viewpoint of the film density and the purity of the film composition.

The underlayer 5 is a layered portion that covers and adheres to the intermediate metal layer 2B, and is formed in an amorphous state from at least one material of tungsten (W) and tungsten carbide (WC).
The metal layer 6 is a layered portion made of a material having good adhesion strength with the base layer 5 and made of at least one metal material of chromium (Cr), Ti, and molybdenum (Mo).
The nitride layer 7 is a layered portion made of a material having good adhesion strength with the metal layer 6 and is made of a nitride containing at least one element of Cr, Ti, and Mo.
The surface layer 8 is a layered portion made of a material that has good adhesion strength with the nitride layer 7 and has good releasability from the glass material used for molding.
Since the surface of the surface layer 8 constitutes the molding surface 2a, it is a mirror surface with a small surface roughness. For example, the arithmetic average roughness _Ra is 0.005 μm or less.
Examples of suitable materials for the surface layer 8 include noble metals. Particularly suitable materials include at least one element selected from the group consisting of platinum (Pt), palladium (Pd), iridium (Ir), osmium (Os), ruthenium (Ru), and rhenium (Re). Examples thereof include an element, an alloy containing at least one element in the element group, and a compound containing at least one element in the element group.

  In such a configuration of the release film 2C, the foundation layer 5 constitutes the lowermost layer laminated on the intermediate metal layer 2B, and the surface layer 8 constitutes the outermost layer that forms the molding surface 2a. .

Examples of particularly suitable film configurations of the release film 2C include the following film configurations.
When the underlayer 5 is made of WC, the metal layer 6 is made of Cr, and the nitride layer 7 is made of CrN, or these are the main components, the surface layer 8 is made of an alloy of Pt and Ir, Ir and Re. An alloy or a metal made of Pt is particularly suitable.
Further, when the underlayer 5 is made of WC, the metal layer 6 is made of Ti, and the nitride layer 7 is made of TiN, or these are the main components, the surface layer 8 is made of an alloy of Pt and Ir, Ir and An alloy with Re and a metal made of Pt are particularly suitable.

  The upper die 3 is a substantially columnar member having a cylindrical side surface 3b having the same outer diameter as that of the side surface 2b of the lower die 2, and protrudes from the side surface 3b to the outer circumferential direction at one axial end (upper side in FIG. 1). A flange 3c is formed, and a molding surface 3a having a convex shape for transferring the shape of the concave lens surface of the optical element to the glass material is formed at the other end in the axial direction (lower side in FIG. 1).

The side surface 3b and the flange portion 3c are formed by the surface of the base material 3A made of the same material as that of the lower mold 2.
On the other end side in the axial direction of the base material 3A, as shown in FIG. 2, an intermediate metal layer 3B and a release film 3C are formed on the base material surface _S3A formed as a concave surface along the shape of the molding surface 3a. The molding surface 3a is constituted by the outermost surfaces of the release film 3C which are laminated in this order.
The intermediate metal layer 3B has the same configuration as the intermediate metal layer 2B of the lower mold 2 and is formed of the same material.
The release film 3C has the same configuration as the release film 2C and is formed of the same material. For this reason, the release film 3C is formed so as to cover the intermediate metal layer 3B.

As shown in FIG. 1, the body mold 4 has an inner peripheral surface 4 a having an inner diameter equal to the outer diameter of the side surface 2 b of the lower mold 2 and the outer diameter of the side surface 3 b of the upper mold 3, and the side surface 2 b of the lower mold 2. , And the side surface 3b of the upper mold 3 are cylindrical members that are slidably fitted in the axial direction.
As a result, one end portion (lower side in FIG. 1) of the body die 4 is fitted to the lower die 2 in a state where the one end portion (lower side in FIG. 1) is engaged with the flange portion 2c of the lower die 2, and the other end portion (upper side in FIG. The upper mold 3 can be removably inserted with the molding surface 3a facing the molding surface 2a.
Thus, in the state where the lower mold 2 and the upper mold 3 are inserted at both ends of the body mold 4, a molding space is formed between the molding surfaces 2a and 3a facing each other.
Silicon carbide and cemented carbide can be used as the material of the trunk mold 4.

Next, the manufacturing method of the lower mold 2 and the upper mold 3 in the mold assembly 1 having such a configuration will be described focusing on the manufacturing process relating to the formation of the molding surfaces 2a and 3a.
Moreover, these manufacturing processes are the same except for the difference in the outer shape of the lower mold 2 and the upper mold 3, and the description of the manufacturing process relating to the formation of the molding surface 2a is the same as the manufacturing process relating to the formation of the molding surface 3a. Applicable to. Therefore, hereinafter, an example in which the molding surface 2a is formed on the lower mold 2 will be described.
Moreover, when describing specific manufacturing conditions, it demonstrates by the example in case the metal 11 consists of Ti.
FIG. 4 is a flowchart showing a process flow of the method for manufacturing an optical element molding die according to the embodiment of the present invention. FIGS. 5A, 5 </ b> B, and 5 </ b> C are schematic process explanatory views of a method for manufacturing an optical element molding die according to an embodiment of the present invention. 6 (a), 6 (b), and 6 (c) are schematic process explanatory views illustrating an intermediate metal layer forming process of the method for manufacturing an optical element molding die according to the embodiment of the present invention.

  As shown in FIG. 4, the manufacturing method of the optical element molding die of this embodiment includes a base material part forming step S1, a carbon nanotube (abbreviated as CNT in FIG. 4) forming step S2, an intermediate metal layer forming step S3, and A release film forming step S4 is provided, and these steps are performed in this order.

Base material part formation process S1 is a process of forming base material 2A which consists of SiC so that it may have the surface of the shape which meets the surface shape of a molded article. In this step, the outer shape of the lower mold 2 is formed, and the surface of the part forming the molding surface 2a is mirror-finished.
The outer shape of the lower mold 2 is formed by sintering SiC. At this time, the part where the molding surface 2a is formed is a curved surface having substantially the same radius of curvature as the molding surface 2a, and has a shape slightly lower than the shape of the molding surface 2a.
Next, a SiC layer is formed by CVD on the surface of the part where the molding surface 2a is to be formed. Thereby, the surface of 2 A of base materials is covered with SiC particle | grains whose particle size is remarkably smaller than sintered particle.
The thickness of the SiC layer is a layer thickness exceeding the layer thickness of the metal buried layer L _1, the surface is shaped to protrude from the shape of the molding surface 2a.
Next, the surface of this SiC layer is polished and smoothed into a shape almost the same as that of the molding surface 2a, for example, finished to a mirror surface with _a surface roughness _Ra of about 0.005 μm or less.
The cross-section shown in FIG. 5 is an enlarged sectional view of the vicinity of the surface S ₀ of the thus mirror-finished substrate 2A.
Above, base material part formation process S1 is complete | finished.

Next, carbon nanotube formation process S2 is performed. This step, as shown in FIG. 5 (b), by heat-treating the substrate 2A, together to volatilize the Si component of the surface S _0, a plurality of forms extend from a surface after volatilization substrate surface S _2A This is a step of forming the carbon nanotube 10.

As the heat treatment of the base material 2A, for example, the base material 2A is placed in an electric furnace having a degree of vacuum of 10 ⁻² Pa and a temperature of 1400 ° C., and heat treatment is performed for 2 hours.
By such heat treatment in a vacuum, SiC is decomposed, Si is volatilized, and C remaining after being dissipated is recombined by carbon bonds to form carbon nanotubes 10.
Meanwhile, since the SiC layer by CVD has a dense structure, the Si is volatilized, the surface S ₀ is gradually uniformly retracted. Therefore, after completion of the heat treatment, in a position from the surface S ₀ was a certain distance, the substrate surface S _2A is formed.
In this heat treatment, C on the surface gradually retreating keeps the same chemical bond as SiC before volatilization of SiC with respect to the SiC bulk of the base material 2A, and van der Waals force, etc. Unlike physical adsorption, it has a strong binding force.
For this reason, the carbon nanotube 10 maintains continuity with the retreating surface, and is in a state of extending substantially vertically from each surface. Therefore, the carbon nanotube 10 is firmly bonded with the substrate surface S _2A, it extends in the same condition as that grow toward the substrate surface S _2A to the surface S _0.
This completes the carbon nanotube formation step S2.

Next, an intermediate metal layer forming step S3 is performed. This step is a step of forming the intermediate metal layer 2B by filling the space between the carbon nanotubes 10 and depositing the metal 11 on the substrate 2A.
In this step, the base material 2A on which the carbon nanotubes 10 are formed is transferred to a CVD apparatus to form a Ti film.
For example, source gas and carrier gases TiCl ₄ , H ₂ , and Ar are supplied at flow rates of ₂ sccm, 80 sccm, and 120 sccm, respectively, the gas pressure in the apparatus is 0.7 Pa, and the microwave power is 2.5 kW (2. 45 GHz) is applied to perform CVD.

As shown in FIG. 6 (a), metal particles 11A which feed gas is generated by decomposition is irradiated toward the carbon nanotubes 10 and the substrate surface S _2A, enters spaces adjacent carbon nanotubes 10, respectively, carbon deposited on the surface and the substrate surface _{S 2A} of the nanotube 10.
At this time, since the high energy metal particles 11 </ b> A adhere to the surface of the carbon nanotube 10, a chemical reaction may occur with the carbon nanotube 10. In this case, the carbide of the metal particles 11 </ b> A is formed on the surface of the carbon nanotube 10 and is chemically bonded, so that it is firmly bonded to the surface of the carbon nanotube 10.

Thus, when the surface of the carbon nanotube 10 is gradually covered with the metal particles 11A, a metal layer 11B made of the metal particles 11A is formed as shown in FIG. 6B.
As the CVD proceeds further, the thickness of the metal layer 11B is increased as shown in FIG. For this reason, the gap between the adjacent carbon nanotubes 10 is narrowed, and the metal particles 11A are further deposited from above the hole-like gap.
As a result, as shown in FIG. 5C, an intermediate metal layer 2B in which the metal 11 is embedded between the carbon nanotubes 10 is formed.
Since the metal particles 11A are uniformly attached from the periphery of each carbon nanotube 10, the metal particles 11A are also attached to the tips of the carbon nanotubes 10, and are deposited so as to cover the entire carbon nanotubes 10 to be intermediate metal layer 2B. Is formed.
In this way, the intermediate metal layer 2B is on the substrate surface S _2A, the embedded metal layer L _1, and a coating layer L ₂ is formed as a layer portion which are laminated in this order.
The intermediate metal layer forming step S3 is thus completed.

Metal embedded layer L ₁ is formed is meshed with the carbon nanotube 10 in a tooth shape, for contact with much larger surface area than the contact plane between, be a physical binding, firmly adhered can do.
In addition, when the metal 11 is a metal that easily forms carbides such as Ti, a TiC chemical bond is easily formed on the surface of the carbon nanotube 10, and thus higher bonding strength can be obtained.
The metal buried layer L ₁ includes a carbon nanotube 10 and the metallic 11 having a microstructure, also said to be in a state of being complexed (mixing). Therefore, improvement of mechanical properties (strength and hardness) can be expected as in the case of the composite material reinforced by adding carbon nanotubes to the metal 11.

Next, a release film forming step S4 is performed. This step is a step of depositing a mold release film 2C on the outermost surface S _2B of the intermediate metal layer 2B.
The base material 2A on which the intermediate metal layer 2B is formed is transferred to a sputtering apparatus. For example, under the same conditions as those used in conventional cemented carbide, the base layer 5, the metal layer 6, and the nitride are formed from the intermediate metal layer 2B side. Layer 7 and surface layer 8 are formed in this order.
Specific examples of each layer include an example in which the underlayer 5 is made of WC, the metal layer 6 is made of Cr, the nitride layer 7 is made of CrN, and the surface layer 8 is made of a mixed film having a composition ratio of Ir and Pt of 1: 1. Can do.
In particular, when the metal 11 is Ti, which has high activity and is easily bonded to various materials, and is suitable as a bonding material, the WC of the underlayer 5 of the release film 2C is chemically bonded to obtain a strong bonding force.
This completes the release film forming step S4.
In this way, the lower mold 2 is manufactured.

  In order to manufacture an optical element with the lower mold 2 of the present embodiment, the mold assembly 1 is formed together with the upper mold 3 manufactured in the same manner, and a glass material is disposed between the lower mold 2 and the upper mold 3. Then, it is heated and pressed. Thereby, the shape of molding surface 2a, 3a is transcribe | transferred to glass material, and in the case of the shape shown in FIG. 1, a meniscus lens can be manufactured.

In order to confirm the effects of the intermediate metal layer 2B and the carbon nanotube 10, as a comparative example, an optical device having the same configuration as the lower mold 2 and the upper mold 3 of the present embodiment except that the intermediate metal layer 2B and the carbon nanotube 10 are not provided. An element molding die was prepared, and glass lenses were molded using the optical element molding die of the present embodiment and the optical element molding die of the comparative example, respectively.
As the glass material, a spherical material having a diameter of 4 mm made of L-LAH53 (trade name; manufactured by OHARA INC.) Was used.
When molding was repeated at a molding temperature of 620 ° C., the optical element molding die of this embodiment did not show deterioration of the molding surface even after molding 1000 shots, whereas the optical element molding die of the comparative example Peeling occurred in a part of the release film after molding 60 shots.
For this reason, since the optical element shaping | molding die of this embodiment is equipped with the intermediate | middle metal layer 2B and the carbon nanotube 10, it turns out that durability of the release film 2C is improving significantly compared with a comparative example.

According to the lower die 2 in this way this embodiment produced as a base material 2A and the release film. 2C, the plurality of carbon nanotubes 10 extending from the substrate surface S _2A of the substrate 2A, the carbon They are stacked via an intermediate metal layer 2B made of a metal 11 embedded in the nanotube 10.
The carbon nanotube 10 is firmly bonded to the substrate surface _S2A by a chemical bond similar to SiC, and the carbon nanotube 10 itself has a strong mechanical strength due to the carbon bond. Since the metal 11 is embedded in such a gap between the carbon nanotubes 10 in a comb shape, the metal 11 is firmly adhered to the carbon nanotubes 10.
The release film 2C is in close contact with the metal 11 on the surface of the intermediate metal layer 2B that is firmly attached to the substrate surface _S2A via the carbon nanotubes 10 in this way.
Thereby, even if it is a case where it is difficult to join with base material 2A because release film 2C is a noble metal system, release film 2C is satisfactorily joined on base material 2A.
For this reason, the durability of the lower mold 2 can be improved.

In the description of the above embodiment, as the optical element molding die, a molding mold for manufacturing an optical element has been described, and an example in which a molding surface that transfers the shape of the optical surface of the optical element is provided. The molding surface that forms the shape of the molded product other than the optical surface can be configured similarly.
The optical element molding die can produce an appropriate molded product that requires a molding surface with good surface accuracy.

Further, in the description of the above embodiment, the film configuration of the release film 2C is such that the base material 2A is a sintered body of SiC, and the release film for the cemented carbide base material is interposed through the intermediate metal layer 2B. In order to show that a mold film can be provided, an example in the case of a multilayer film having a four-layer structure in which the base layer 5, the metal layer 6, the nitride layer 7, and the surface layer 8 are laminated in this order has been described.
According to such a configuration, even when the material of the base material 2A is other than the cemented carbide, the conventional release film for the cemented carbide base material and the manufacturing process for forming the release film remain unchanged. Can be used. For this reason, the adhesive strength with the base material 2A of the optical element molding die can be improved without changing the release film.
However, such a film configuration of the release film is an example, and the release film can have an appropriate film configuration if the adhesion strength with the metal 11 used for the intermediate metal layer 2B is good. That is, the film configuration of the above embodiment has the configuration of the surface layer 8 that is the outermost layer and the base layer 5, the metal layer 6, and the nitride layer 7 that are other intermediate layers. As the material and the layer configuration (layer combination and order), an appropriate material and layer configuration can be adopted according to the material of the outermost layer and the required adhesion strength.
For example, some of these intermediate layers may be deleted, each may be provided with a plurality of different materials and compositions, another different intermediate layer may be inserted, or the layer stacking order may be changed. Good.
Further, at least a part of the intermediate layer of the release film may be a material gradient layer in which the material composition changes in the layer thickness direction.
Further, the release film may be a single layer in which the same material is uniformly distributed, or may be a single layer made of a material gradient layer.

  In the description of the above embodiment, an example in which the entire base material 2A is made of SiC has been described. However, an SiC layer for forming the carbon nanotubes 10 may be provided in a region where the molding surface 2a is formed. For example, materials other than SiC can be adopted as the material of the other part of the base material 2A.

In the description of the above embodiments, the coating layer L ₂ is, was described using an example of a case which is formed so as to cover all the tips of the carbon nanotubes 10, be exposed the tip of the carbon nanotube 10, the release When the contact area between the film 2 </ b> C and the metal 11 is large enough to obtain the necessary adhesion strength, the tip of the carbon nanotube 10 may not be covered with the metal 11. That is, it is also possible to omit the covering layer L ₂ in the intermediate metal layer 2B.

  Further, all the components described in the above embodiment can be implemented by appropriately changing or deleting the combination within the scope of the technical idea of the present invention.

1 Mold assembly 2 Lower mold (Optical element molding mold)
2A, 3A base material (base material part)
2B, 3B Intermediate metal layer 2C, 3C Mold release film 2a, 3a Molding surface 3 Upper mold (Optical element molding mold)
4 Body type 5 Underlayer (lowermost layer)
6 Metal layer 7 Nitride layer 8 Surface layer (outermost layer)
10 the carbon nanotubes 11 metal _{S 2A, S 3A} substrate surface _{S 2B, S 3B} outermost surface S1 base portion forming process S2 of carbon nanotubes (CNT) forming process S3 intermediate metal layer forming step S4 release film forming step

Claims (8)

A base portion made of silicon carbide having a surface shaped along the surface shape of the molded article;
A plurality of carbon nanotubes extending from the surface;
An intermediate metal layer made of metal buried between the carbon nanotubes and deposited on the substrate part;
A release film laminated on the intermediate metal layer;
An optical element molding die comprising: The optical element molding die according to claim 1, wherein the metal is made of one or more of titanium, zirconium, and molybdenum. 3. The optical element molding die according to claim 1, wherein a carbide of the metal is formed between the intermediate metal layer and the carbon nanotube. 4. The release film is a multilayer film including at least a lowermost layer laminated on the intermediate metal layer and an outermost layer having a molding surface that is in close contact with the material of the molded product so as to be releasable. The optical element shaping | molding die of any one of Claims 1-3. The optical element molding die according to any one of claims 1 to 4, wherein the metal is a metal used for the release film. Using the optical element molding die according to any one of claims 1 to 5, molding the material of the molded product to obtain the molded product,
A method for manufacturing an optical element. A base material part forming step for forming a base material part made of silicon carbide so as to have a surface having a shape conforming to the surface shape of the molded article;
The carbon nanotube forming step of heat-treating the base material part to volatilize the silicon component on the surface and forming a plurality of carbon nanotubes extending from the surface of the base material part;
An intermediate metal layer forming step of forming an intermediate metal layer by filling a metal between the carbon nanotubes and depositing the metal on the substrate part;
A release film forming step of forming a release film on the intermediate metal layer;
A method for producing an optical element molding die, comprising: Using the optical element molding die obtained by the method for producing an optical element molding die according to claim 7, the material of the molded product is molded to obtain the molded product.
A method for manufacturing an optical element.

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