JP2014069984A - Method for manufacturing molding die for press molding, the molding die for press molding, and method for manufacturing glass optical element using the molding die for press molding - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing a molding die for press molding capable of molding a lens with less appearance defects, the molding die having a mold release film including a carbon film formed using a thin film forming apparatus.SOLUTION: A method for manufacturing a molding die for press molding having a mold release film including a carbon film formed by generating carbon plasma on a carbon cathode using a vacuum arc discharging, by extracting only ionized carbon from the plasma and by irradiating the ionized carbon on a film forming surface, includes: a process in which a first carbon film having a thickness of d(nm) is formed by applying a first bias voltage V(V) to the film forming surface; and a process in which a second carbon film as an outermost layer having a thickness of d(nm) is formed on the first carbon film by applying a second bias voltage V(V) to the first carbon film, the first and second bias voltages Vand Vand the thicknesses dand dsatisfying relationships of V>Vand d>d.

Description

  The present invention relates to a method for manufacturing a mold press mold having a release film, which is used when manufacturing an optical element such as a lens by press molding, and the mold press mold. Specifically, a lens with few appearance defects can be molded, and carbon plasma is generated on the carbon cathode by vacuum arc discharge, and only ionized carbon is taken out from the carbon plasma, and the ionized carbon is applied to the surface on which the carbon plasma is deposited. The present invention relates to a method for manufacturing a mold press mold including a release film including a carbon film formed by irradiating the film and a mold press mold.

The precision press molding method is also called mold optics molding method. By precisely transferring the molding surface of the press mold to glass, the optical function surface in press molding, for example, a lens is taken as an example. And a lens surface such as a spherical surface of a spherical lens. That is, since it is not necessary to perform machining such as grinding or polishing in order to finish the optical functional surface, an optical element, particularly an aspherical lens, can be manufactured with high productivity.
Conventionally, various materials such as SiC, cemented carbide, metals such as stainless steel, and ceramics have been used as mold materials for molds used in this type of method. In order to improve the above, it has been proposed to provide a release film such as a carbon-containing film or a noble metal alloy film on the mold. Among them, a mold having a release film including a carbon film such as a diamond-like carbon film, a hydrogenated amorphous carbon film (aC: H film), a hard carbon film, or a tetrahedral amorphous carbon film (taC film) is a mold release. It has the advantage that it has good properties and is less likely to cause fusion with glass.
However, such a carbon film is worn out as the mold press molding operation is repeated, so that sufficient molding performance cannot be obtained, and there is a problem in durability. Therefore, in order to improve the durability of the release film, it has been proposed to use a film whose hardness is not easily lowered during molding.
For example, Patent Document 1 (Japanese Patent Laid-Open No. 2012-12286) discloses that a taC film is formed on a mold base material of an optical element molding die by a filtered cathodic vacuum arc method (hereinafter referred to as an FCVA method). Has been. The FCVA method is a method in which only charged particles with uniform energy are extracted from an arc discharge of a carbon electrode, and a uniform and high-density thin film is formed on a substrate. According to this method, a taC film with high-strength sp3 bonds that does not contain hydrogen can be obtained.
Patent Document 2 (Japanese Unexamined Patent Application Publication No. 2009-199637) discloses forming a taC film on a magnetic recording medium by a filtered cathodic arc method (hereinafter referred to as FCA method). In the FCA method, a pure graphite target is used as a cathode, an arc is generated on the target by arc discharge to generate carbon plasma, and ions in the plasma are drawn into the substrate by a negative bias or the like to form a carbon film. Since the carbon film formed by such a method has a high ratio of the sp3 component to the sp2 component, a hard and durable carbon film can be obtained.
Note that the FCVA method and the FCA method represent the same manufacturing method with different names. Similar names include the Filtered Vacuum Arc method (hereinafter referred to as the FVA method), the Filtered Arc Deposition method (hereinafter referred to as the FAD method), and these are all the same manufacturing method. Since the carbon film formed by this manufacturing method has a high sp3 component ratio, a carbon film with high hardness can be obtained.

JP2012-12286A JP 2009-199637 A

However, when an optical element is formed by press-molding a glass to be molded using a mold having a taC film formed by the FCVA method described above, foaming, scratches, cloudiness, etc. are formed on the molded optical element. There was a problem that the appearance was poor and the yield was lowered.
The present invention has been made in order to solve the above-mentioned problems peculiar to a mold having a carbon film by the FCVA method or the like, and a mold having a release film including a carbon film capable of forming a lens with a small appearance defect. It aims at providing the manufacturing method of a press-molding die.

A specific bias voltage is applied in the formation of a carbon film by generating carbon plasma on the carbon cathode by vacuum arc discharge, extracting only the ionized carbon from the carbon plasma, and irradiating the deposition surface with the ionized carbon. However, it has been found that a release film in which appearance defects such as foaming and scratches are suppressed can be obtained by a production method in which a carbon film composed of at least two layers is formed.
That is, the present invention includes a carbon film formed by generating carbon plasma on a carbon cathode by vacuum arc discharge, extracting only ionized carbon from the carbon plasma, and irradiating the film formation surface with ionized carbon. A mold press mold manufacturing method including a release film, wherein a first carbon film having a thickness d ₁ (nm) is applied to a film formation surface while applying a _first bias voltage V ₁ (V). And a second carbon film having a thickness of d ₂ (nm) for forming an outermost layer while applying a _second bias voltage V ₂ (V) on the first carbon film. The first and second bias voltages V ₁ and V _{2 and the} thicknesses d ₁ and d ₂ provide a manufacturing method that satisfies V ₁ > V ₂ and d ₁ > d ₂ .

  ADVANTAGE OF THE INVENTION According to this invention, the manufacturing method of a mold press shaping | molding die provided with the release film containing the carbon film which can shape | mold a lens with few external appearance defects can be provided.

It is a figure for demonstrating the apparatus structure of the mold release film forming apparatus 100 used for the film-forming process by FCVA method. 1 is a diagram illustrating a configuration of a release film of Example 1. FIG. It is a figure which shows the structure of the release film of the examination example 1. FIG. It is a figure which shows the structure of the release film of the examination example 2. FIG. It is a figure which shows the structure of the release film of Example 7. FIG.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings. In addition, the same code | symbol is attached | subjected to the same or equivalent part in a figure, and the description is not repeated.

In the present invention, the carbon film is formed by generating carbon plasma on the carbon cathode by vacuum arc discharge, taking out only ionized carbon from the carbon plasma, and irradiating the film formation surface with ionized carbon.
In the present invention, the carbon cathode is preferably a graphite cathode, more preferably a pure graphite cathode.
In the present invention, the vacuum arc discharge is performed according to a conventional method.
Further, in the present invention, the method of extracting only ionized carbon from the carbon plasma includes filtering by a magnetic field, but any method capable of filtering droplets that degrade the film quality generated simultaneously with the generation of the carbon plasma. There is no particular limitation.
Examples of the film forming method include the filtered cathodic vacuum arc method (hereinafter referred to as FCVA method), the filtered cathodic arc method (hereinafter referred to as FCA method), the filtered vacuum arc method (hereinafter referred to as FVA method), and the filtered arc deposition. Method (hereinafter referred to as FAD method).
For example, in the FCVA method, carbon plasma is generated by vacuum arc discharge using a graphite cathode as a target, only ionized carbon is extracted by an electromagnetic spatial filter, and ionized on the substrate by applying a negative bias voltage to the substrate. This is a method of drawing in carbon and forming a carbon film.
Here, the electromagnetic spatial filter arranges the substrate at a position where the cathode is not directly visible, that is, the substrate is disposed at a position where the cathode and the substrate are not in a straight line, and the plasma generated from the cathode is electromagnetically bent or It is a filter that can filter droplets that deteriorate the film quality that occurs simultaneously with the generation of carbon plasma during plasma transport by bending.
According to the method of the present invention, the film can be formed at room temperature, and the obtained carbon film does not contain hydrogen that causes the film to decrease in hardness when heated, has a controllable high hardness, and has a smooth surface. Has the advantage.

One aspect of the carbon film forming step in the present invention will be described below.
FIG. 1 is a diagram for explaining the equipment configuration of a release film forming apparatus 100 based on the FCVA method. Referring to FIG. 1, this forming apparatus 100 includes a support plate 10 and a forming die 20 that is a film formation object in a vacuum chamber 1. Here, the support plate 10 is made of a conductive material such as an aluminum alloy.
A vacuum arc power source 2, an arc plasma generation chamber 3, a plasma transport tube 4, and a filter coil 5 for forming a tetrahedral amorphous carbon film (taC film) by the FCVA method are connected to the vacuum chamber 1.
The arc plasma generation chamber 3 includes a vacuum arc evaporation source that generates a plasma containing a cathode material by evaporating the cathode by vacuum arc discharge. The plasma transport tube 4 has a bent shape and is connected to the arc plasma generation chamber 3 and the vacuum chamber 1, and a filter coil 5 that forms a magnetic field is wound around the transport tube 4.

Next, a film forming process for forming a taC film on the mold 20 using this apparatus will be described below.
In the vacuum chamber 1, the mold 20 is disposed so that the normal direction of the film formation surface and the traveling direction of the ionized carbon 7 deflected by the filter coil 5 are parallel to each other. The ultimate vacuum in the vacuum chamber 1 is evacuated by a vacuum pump (not shown) until it reaches 1 × 10 ⁻⁴ Pa or less. Next, a carbon plasma is generated in the arc plasma generation chamber 3 by the vacuum arc power source 2, and a desired current is controlled by the filter coil 5 to extract only the ionized carbon 7. Further, the filter coil 5 is controlled to have a desired current, the ionized carbon 7 is scanned, and a uniform taC thin film is formed on the molding surface (film formation surface) of the molding die 20 disposed on the support plate 10. Form. Further, by applying a bias voltage to the support plate 10 and the mold 20, the energy level of ion particles constituting the taC film can be changed.

The hardness of the film by the FCVA method can be adjusted by a bias voltage applied to the support plate 10 and the mold 20, and shows the highest hardness at a bias voltage of about −100 V, and the hardness decreases when the bias voltage is lowered.
In the present invention, a high-hardness film (first carbon film) formed with a negative bias voltage having a small absolute value of the bias voltage is formed as an underlayer, and the outermost layer is thinner than the underlayer and is biased. By adopting a configuration in which a low-hardness film (second carbon film) formed with a negative bias voltage having a large absolute value of voltage is formed, the followability of the glass with respect to the release film changes, and the inside of the glass changes from the inside to the outside. It is considered that the released gas easily escapes to the outer peripheral portion of the mold, and occurrence of appearance defects such as foaming is suppressed.

Therefore, the film forming step of the present invention includes a step of forming a first carbon film having a thickness of d ₁ (nm) while applying a _first bias voltage V ₁ (V) to the film formation surface, and Forming a second carbon film having a thickness of d ₂ (nm) to form an outermost layer on the first carbon film while applying a _second bias voltage V ₂ (V); The step of forming the first carbon film and the step of forming the second carbon film can be performed continuously by changing the applied voltage.

In the present invention, the second bias voltage V ₂ (V) is lower than the _first bias voltage V ₁ (V).
The first bias voltage V ₁ (V) is preferably −400 ≦ V ₁ ≦ −10, more preferably −150 ≦ V ₁ ≦ −10.
The second bias voltage V ₂ (V) is preferably V ₂ ≦ −1100, and more preferably V ₂ ≦ −1200. The second bias voltage V ₂ (V) is preferably V ₂ ≧ -4000, more preferably V ₂ ≧ -3000, more preferably from V ₂ ≧ -2500.
In the preferred range, occurrence of appearance defects such as foaming, scratches, and cloudiness is suppressed.

In the present invention, the thickness d ₁ (nm) of the first carbon film is thicker than the thickness d ₂ (nm) of the second carbon film.
The thickness d ₁ (nm) of the first carbon film is preferably d ₁ ≧ 10, and more preferably d ₁ ≧ 20. The thickness d ₁ (nm) of the first carbon film is preferably d ₁ ≦ 1000, more preferably d ₁ ≦ 300.
The thickness d ₂ (nm) of the second carbon film is preferably d ₂ ≧ 7, more preferably d ₂ ≧ 10. The thickness d ₂ (nm) of the second carbon film is preferably d ₂ ≦ 200, more preferably d ₂ ≦ 100.
In the preferred range, occurrence of appearance defects such as foaming, scratches, and cloudiness is suppressed.

The manufacturing method of the molding die in the present invention further adheres between the first carbon film and the molding die 20 in order to ensure the adhesion between the molding die 20 and the release film and prevent the release film from peeling during pressing. A step of forming a layer may be included. The adhesive layer can be appropriately selected in relation to the material of the mold 20, and when the mold 20 is SiC, the first layer from the deposition surface side: bias voltage is −1500 to −1 by FCVA method. -1000 V, film thickness of 5 to 15 nm, second layer: an adhesive layer composed of two layers having a bias voltage of -1000 to -300 V and a film thickness of 10 to 30 nm can be formed. For example, an adhesive layer including two layers of a first layer: a bias voltage of −1200 V and a film thickness of 10 nm, and a second layer: a bias voltage of −900 V and a film thickness of 20 nm is formed.
In the present invention, the adhesive layer is not limited to two layers, and may be a single layer or three or more layers. By providing the adhesive layer, the adhesion strength between the mold 20 and the first carbon film is improved. To do.

In the present invention, the mold press mold is preferably used for molding a glass optical element.
The mold press mold in the present invention is more preferably used when a glass optical element is produced by a mold optics molding method.
The mold optics molding method accurately transfers the molding surface of a press mold to glass, so that when an optical function surface is used in press molding, for example, a lens, an aspherical lens or a spherical lens is used. A method of forming a surface. That is, since it is not necessary to perform machining such as grinding or polishing in order to finish the optical functional surface, an optical element, particularly an aspherical lens, can be manufactured with high productivity.
In the present invention, examples of the glass optical element include lenses such as spherical lenses and aspheric lenses, prisms, diffraction gratings, and the like. As the shape of the lens, various shapes such as a biconvex lens, a plano-convex lens, a biconcave lens, a plano-concave lens, a convex meniscus lens, and a concave meniscus lens can be shown. Moreover, there is no restriction | limiting in particular about the magnitude | size of a lens.

In the present invention, the mold press mold is provided with a release film including a carbon film formed by the film forming process on the molding surface of the mold material. For example, in the case of a mold press mold used when a glass optical element is manufactured by a mold optics molding method, a release film is provided on molding surfaces of an upper mold and a lower mold that are in contact with glass to be molded. Depending on the shape of the optical element, a cylinder called a sleeve is used as a support for the upper and lower molds in addition to the upper mold and the lower mold. A release film is also provided on the surface of the inner wall of the sleeve that contacts the glass to be molded.
The mold material of the mold press mold in the present invention includes SiC (silicon carbide), but is not limited thereto, cemented carbide mainly composed of WC (tungsten carbide), metals such as stainless steel, various types Ceramics can also be used.

The present invention includes a glass optical element manufacturing method in which a glass to be molded is press-molded using the mold press mold manufactured as described above to manufacture a glass optical element.
When the glass optical element is press-molded, a known mold optics molding method can be used. For example, after supplying a glass material heated to a predetermined temperature into a mold including an upper mold and a lower mold, or by placing a glass material at room temperature in the mold and heating the glass material to a predetermined temperature together with the mold Thereafter, a load is applied to the mold and press molding of the glass material is started. Eventually, after the glass material is deformed into a desired shape by the upper mold and the lower mold, the mold and the glass material are cooled. When the temperature is lowered to the glass transition point or lower, the glass optical element can be produced by taking out the molded glass optical element from the mold.

Here, the hardness of the carbon film in the present invention will be described.
In the present invention, the hardness of the second carbon film measured by the nanoindentation method (hereinafter referred to as “nanoindentation hardness”) is 30 GPa or less, and the nanoindentation hardness of the first carbon film is second. It is higher than the nanoindentation hardness of the carbon film.
In the present invention, the nanoindentation hardness was measured using a nanoindentation hardness apparatus ENT-2100 (manufactured by Elionix). Since this method is a method for converting the indentation depth of the indenter into the sample, the hardness is a value affected by the substrate when the sample is thin. Therefore, a carbon single layer film having a thickness of 100 nm, which is sufficiently thick with respect to the indentation depth, was formed on the SiC substrate to prepare a sample. In the measurement, a triangular pyramid diamond indenter (Belkovic indenter) having a tip-to-edge angle of 115 ° was used as the indenter. A triangular pyramid-shaped diamond indenter is applied to the sample surface at right angles, and a load is gradually applied under the conditions of a load of 10 mgf, an addition time of 10 seconds, a holding time of 1 second, and an unloading time of 10 seconds. It gradually returned to. A value P / A obtained by dividing the maximum load P at this time by the contact projected area A of the indenter contact portion was calculated as nanoindentation hardness (H).
Details of the principle are described in “Mechanical property evaluation of thin film by nanoindentation method” (R & D KOBE STEEL ENGINEERING REPORTS Vol.52 No.2).

In the present invention, the dynamic friction coefficient of the second carbon film is 0.2 or less, and the dynamic friction coefficient of the first carbon film is larger than the dynamic friction coefficient of the second carbon film.
The dynamic friction coefficient was evaluated using a reciprocating dynamic friction coefficient measuring instrument. Specifically, glass was used as the contact, the load applied to the contact was 5 mgf, and the sample sliding speed was 0.15 mm / second.

Before examining the appearance evaluation of the press-molded body using the mold having the mold release film of Example 1, first, the process of forming the mold release film on the mold press mold will be described.
(Film formation process by FCVA method)
After the SiC mold 20 was cleaned, it was placed in an FCVA apparatus (model number MTCS-7B, Nano Film Technologies International PTE., LTD. (Singapore)), and ion beam etching was performed under the following conditions.
-Ultimate pressure <1 x ^10-4 Pa
-Ar gas 30 sccm
-Process pressure 0.2-0.4Pa
-Ion beam voltage 600V
− Bias voltage 0V
-Substrate temperature Room temperature-Processing time 800 seconds Next, a predetermined bias voltage was set under the following conditions to form a carbon film having a predetermined thickness. That is, two layers of a film 51 having a thickness of 10 nm formed at a bias voltage of −1200 V and a film 52 having a thickness of 20 nm formed at a bias voltage of −900 V are formed on the molding surface (molded surface) of the mold 20. The adhesion layer 50 made of the carbon film was formed, and then the bias voltage was changed and the first carbon film 30 and the second carbon film 40 were formed thereon.
-Ultimate pressure <1 x ^10-4 Pa
-Arc current 40A
-Anode coil current 5A
-Double bend filter current 13A
-Duct voltage 15V
-Substrate temperature Room temperature FIG. 2 is a view showing the structure of the release film of Example 1. FIG. Referring to FIG. 2, in Example 1, the adhesive layer 50, the first carbon film 30: the bias voltage is −120 V, the film thickness is 70 nm, and the second carbon film 40: the bias voltage is −1200 V, and the film thickness is 20 nm. This is a SiC mold 20 including the release film 6 to be configured.
On the other hand, in order to facilitate understanding of the first embodiment, further description will be given using the first and second study examples. FIG. 3 and FIG. 4 are diagrams showing the configuration of the release films of the study examples 1 and 2. FIG. In the film formation methods of the examination examples 1 and 2, the release film having a desired film thickness is formed by appropriately changing the application time of the bias voltage under the same conditions as the film formation process described above.
With reference to FIGS. 3 and 4, Examples 1 and 2 are molds in which a film corresponding to the second carbon film 40 of the present invention is not formed. Specifically, the study example 1 is the first carbon film 31: a mold having a release film composed of only a bias voltage of −1200 V and a film thickness of 100 nm, and the study example 2 is the adhesive layer 50 and the first carbon film. 32: A mold having a release film composed of a bias voltage of −120 V and a film thickness of 70 nm.

(Appearance evaluation method)
Using a mold press mold with an outer diameter of φ45, each with a release film installed by the above method, precision press-molding a molding material made of optical glass at a press temperature of 582 ° C. and a pressed load of 300 kgf using an isothermal press molding machine. A biconvex lens was manufactured.
The obtained lens was visually observed with a condensing lamp, (1) the presence or absence of foaming and white turbidity in the center, (2) the presence or absence of radial flaws in the periphery, and (1) and (2) none Those with the occurrence of either (1) or (2) were evaluated as “bad”.

The obtained results are shown in Table 1. The upper part of the film configuration column is the bias voltage, and the lower part is the film thickness.

[Evaluation of the outermost layer thickness (variable) when the thickness of the underlayer is constant]
Next, as in Example 1, the adhesive layer 50 and the base layer (first carbon film) 30 were formed, and the appearance observation was evaluated when the thickness of the outermost layer (second carbon film) 40 was changed. . Specifically, in Examples 2 and 3 and Comparative Example 1, the carbon film of the base layer has a bias voltage of −120 V and a film thickness of 70 nm in common, and the film thickness of the outermost layer is changed to 5, 10, 20, and 30 nm. Evaluation of appearance observation was performed. Table 2 shows the evaluation results of the appearance observation. For reference, Table 2 also shows the results of Example 1 for reference.
Here, in the film forming methods of Examples 2 and 3 and Comparative Example 1, a release film having a desired film thickness is obtained by appropriately changing the application time of the bias voltage under the same conditions as the film forming process described above. Forming.

[Evaluation of the film thickness (constant) of the outermost layer when the film thickness of the underlayer is variable]
Next, an adhesive layer 50 and a base layer (first carbon film) 30 are formed in the same manner as in Example 1, and the outermost layer is a second carbon film 40 having a bias voltage of −1200 V and a film thickness of 30 nm. Evaluation was performed when the film thickness of the first carbon film was changed. Specifically, in Examples 4 and 5 and Comparative Example 2, the outermost layer (second carbon film) has a bias voltage of −1200 V and a thickness of 30 nm, and the thickness of the underlayer is 20, 40, and 70 nm. The appearance observation was evaluated in the order of change. Table 3 shows the evaluation results of the appearance observation.
Here, in the film forming methods of Examples 4 and 5 and Comparative Example 2, a release film having a desired film thickness was obtained by appropriately changing the application time of the bias voltage under the same conditions as the film forming process described above. Forming.

[Evaluation of outermost layer bias voltage]
Example 6 and Comparative Examples 3 to 5
Table 4 shows the results of appearance observation when the adhesive layer 20 and the base layer (first carbon film) 30 are formed in the same manner as in Example 1 and the bias voltage of the outermost layer (second carbon film) 40 is changed.

[Evaluation of physical properties of carbon film]
For the bias layer A (bias voltage −120 V), bias layer B (bias voltage −1200 V), bias layer C (bias voltage −900 V) and SiC substrate obtained by the FCVA film formation process, the hardness is measured by the following method. And the coefficient of dynamic friction was evaluated.
(Hardness measurement conditions)
Nano-indentation hardness was measured using a device ENT-2100 (manufactured by Elionix), a Belkovic indenter as an indenter, a load of 10 mgf, an addition time of 10 seconds, a holding time of 1 second, an unloading time of 10 seconds, and a carbon film formed on the sample. Measurement was performed under the condition of a thickness of 100 nm.

(Friction coefficient measurement conditions)
The dynamic friction coefficient was measured by using a reciprocating friction coefficient measuring device, using glass as a contactor, a load of 5 mgf applied to the contactor, and a sliding speed of the sample of 0.15 mm / second. The measurement results are shown in Table 5.

Example 7 [Evaluation when outermost layer is multi-layer]
FIG. 5 is a view showing the structure of the release film of Example 7. Referring to FIG. 5, by the above FCVA method film forming process, adhesive layer 50, first carbon film 30: second carbon film having a bias voltage of −120 V and a film thickness of 70 nm are formed on mold 20. 41 has a multi-layer in which a layer 42 having a bias voltage of −1200 V and a thickness of 1 nm and a layer 43 having a bias voltage of −150 V and a thickness of 1 nm are alternately stacked to have a total thickness of 20 nm. A release film 6 ′ having a configuration of 120 nm was produced (see FIG. 5). Example 7 is different from Example 1 in that the second carbon film 40 (bias voltage is −1200 V and film thickness is 20 nm), which is the outermost layer in Example 1, is formed in a multi-layer.
The appearance of the lens obtained using the mold press mold provided with the release film 6 ′ of Example 7 was evaluated in the same manner as in Example 1, and was good.

Finally, the first embodiment will be summarized with reference to the drawings and the like.
Includes a carbon film formed by generating carbon plasma on a carbon target by the cathode arc discharge of Embodiment 1, extracting only ionized carbon from the carbon plasma, and irradiating the film formation surface with ionized carbon As shown in FIGS. 1 and 2, the method for producing a mold press mold 20 having a release film forms a carbon film 30 having a thickness of 70 nm on a film formation surface while applying a bias voltage of −120 V. And a step of forming a carbon film 40 having a thickness of 20 nm to form an outermost layer while applying a bias voltage of −1200 V on the carbon film 30, including a bias voltage of −120 V, −1200 V, and a thickness of 70 nm. , 20 nm is (the bias voltage of the carbon film 30 −120 V)> (the bias voltage of the carbon film 40 −1200 V) and (carbon The thickness of the film 30 70 nm)> satisfy (thickness 20nm of the carbon film 40).
Preferably, as shown in FIG. 2, the bias voltage (−1200 V) of the carbon film 40 is −1100 V or less, and the thickness (20 nm) of the carbon film 40 is 7 nm or more.
Preferably, as shown in FIG. 2, the bias voltage (−120V) of the carbon film 30 is −10V or less and −400V or more.
Further, preferably, the manufacturing method includes a step of further forming an adhesive layer 50 between the carbon film 30 and the mold press mold 20 as shown in FIG.
More preferably, as shown in Table 5, the carbon film 30 and the carbon film 40 formed on the mold press mold 20 have a hardness measured by the nanoindentation method of the carbon film 40 of 30 GPa or less. The hardness of the carbon film 30 measured by the nanoindentation method is higher than the hardness of the carbon film 40 measured by the nanoindentation method.
More preferably, as shown in Table 5, the carbon film 30 and the carbon film 40 formed on the mold press mold 20 have a dynamic friction coefficient of 0.2 or less, and the carbon film The dynamic friction coefficient of 30 is larger than the dynamic friction coefficient of the carbon film 40.
By adopting such a configuration, the followability of the glass with respect to the release film is changed, gas released from the inside of the glass to the outside easily escapes to the outer periphery of the mold, and occurrence of appearance defects such as foaming is suppressed.
Moreover, a glass optical element can be manufactured by press-molding glass to be molded using the mold press-molding die manufactured as described above. According to such a method for producing a glass optical element, it is possible to obtain a good glass optical element having no appearance defects such as foaming, cloudiness, and scratches.
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.

DESCRIPTION OF SYMBOLS 1 Vacuum chamber 2 Vacuum arc power supply 3 Arc plasma generation chamber 4 Plasma transport pipe 5 Filter coil 6 Release film 6 'Release film 7 Ionized carbon 10 Support plate 20 SiC mold 30 First carbon film (bias voltage) -120V, film thickness 70nm)
31 1st carbon film (bias voltage -1200V, film thickness 100nm)
32 1st carbon film (bias voltage -120V, film thickness 70nm)
40 Second carbon film (bias voltage-1200 V, film thickness 20 nm)
41 Second carbon film (multi-layer, film thickness meter 20 nm)
42 Carbon film constituting multi-layer (bias voltage-1200V, film thickness 1nm)
43 Multi-layer carbon film (bias voltage -150V, film thickness 1nm)
50 adhesive layer 51 1st adhesive layer (bias voltage -1200V, film thickness 10nm)
52 2nd adhesion layer (bias voltage -900V, film thickness 20nm)
100 Release film forming apparatus by FCVA method

Claims (8)

A release film including a carbon film formed by generating carbon plasma on a carbon cathode by vacuum arc discharge, taking out only ionized carbon from the carbon plasma, and irradiating the film formation surface with the ionized carbon A method for producing a mold press mold comprising:
Forming a first carbon film having a thickness of d ₁ while applying a _first bias voltage V ₁ on the film formation surface;
Forming a second carbon film having a thickness of d ₂ to form an outermost layer while applying a _second bias voltage V ₂ on the first carbon film,
The first and second bias voltages V ₁ and V _{2 and the} thicknesses d ₁ and d ₂ are:
V ₁ > V ₂ and d ₁ > d ₂
The manufacturing method of a mold press mold provided with the release film which satisfy | fills. 2. The manufacturing method according to claim 1, wherein the second bias voltage V ₂ is −1100 V or less and the thickness d ₂ is 7 nm or more. The manufacturing method according to claim 2, wherein the first bias voltage V ₁ is −10 V or less and −400 V or more.   The manufacturing method of any one of Claims 1-3 including the process of forming an adhesive layer further between the said 1st carbon film and the said mold press shaping | molding die.   The mold press molding die manufactured by the manufacturing method as described in any one of Claims 1-4.   The hardness measured by the nanoindentation method of the second carbon film is 30 GPa or less, and the hardness measured by the nanoindentation method of the first carbon film is measured by the nanoindentation method of the second carbon film. The mold press mold according to claim 5, wherein the mold press mold is higher than the hardness to be achieved.   The mold according to claim 5 or 6, wherein a dynamic friction coefficient of the second carbon film is 0.2 or less, and a dynamic friction coefficient of the first carbon film is larger than a dynamic friction coefficient of the second carbon film. Press mold.   The manufacturing method of the glass optical element which press-molds glass to be molded using the mold press molding die as described in any one of Claims 5-7, and manufactures a glass optical element.

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