JP2018154515A - Glass molding die and method for producing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a glass molding die that has high durability even when molding a large diameter aspherical glass lens and can mold the large diameter aspherical glass lens that is excellent in appearance.SOLUTION: A die 10 contains a first layer 12, a second layer 13 and a third layer 14 sequentially laminated on a base material 11. The base material 11 contains a cemented carbide. The first layer 12 contains one or more selected from the group consisting of a tungsten carbide, a titanium carbide and a tantalum carbide. The second layer 13 contains a silicone carbide. The third layer 14 contains diamond-like carbon.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a glass mold, a method for manufacturing a glass mold, and a method for manufacturing an aspheric glass lens.

  In recent years, with an increase in the size of an imaging element of a camera lens and advancement of image quality performance, there is an increasing need for an aspheric glass lens having a large diameter of 50 mm or more in the glass mold field.

  The glass mold is a method of transferring the shape of a mold by heating and softening a glass material to approximately 500 ° C. or higher and then press-molding it.

  An aspheric glass lens is difficult to polish like a normal spherical glass lens. For this reason, in the optical field including a camera lens and a projector lens, a glass mold is widely used as a mass production technique for an aspheric glass lens.

  Here, when a release film is not formed on the surface of the mold during pressing, the cemented carbide and the glass material constituting the mold chemically react to cause troubles such as fusion. As a result, the appearance of the aspheric glass lens is degraded. For this reason, a release film is generally formed on the surface of the mold.

  As materials for forming the release film, noble metals and DLC (diamond-like carbon) are known.

  Since DLC is excellent in non-adhesiveness to a glass material, the appearance of an aspheric glass lens after molding is clear as compared with a noble metal.

  However, since DLC is generally difficult to adhere to the cemented carbide constituting the mold, when the DLC is used as a material constituting the release film, the release film is easily peeled off. In particular, in a glass mold of a large-diameter aspheric glass lens, the load (load) during pressing becomes a high load environment of about 1 to 3 t, so that the release film is easy to peel off and the durability of the mold is sufficient. It will be impossible to secure.

  Therefore, as a conventional technique for improving the durability of a mold, there is a molding mold having a molding surface on a part of a base material. For example, in Patent Document 1, a layer made of metallic titanium, a layer made of titanium aluminum nitride, a layer made of silicon carbide, and a layer made of tetrahedral amorphous carbon are sequentially laminated on the molding surface.

  However, it has been experimentally found that the prior art has a problem that when an aspheric glass lens having a large diameter is molded, the appearance of the aspheric glass lens is often insufficient. Specifically, there is a problem that the appearance of the aspherical glass lens deteriorates due to frequent occurrence of minute foreign matters due to peeling of the release film during glass molding, and a layer made of metallic titanium or titanium aluminum nitride during glass molding. When Ti diffuses thermally from the layer, there may be a problem that the aspheric glass lens is very thinly colored.

  The present invention provides a mold for a glass mold capable of molding a large-diameter aspheric glass lens having high durability and excellent appearance even when a large-diameter aspheric glass lens is molded. With the goal.

  In one embodiment of the present invention, in the glass mold, a first layer, a second layer, and a third layer are sequentially stacked on a base material, the base material including a cemented carbide, One layer includes one or more selected from the group consisting of tungsten carbide, titanium carbide, and tantalum carbide, the second layer includes silicon carbide, and the third layer includes diamond-like carbon.

  According to the present invention, there is provided a glass mold die capable of molding a large-diameter aspherical glass lens having high durability and excellent appearance even when a large-diameter aspherical glass lens is molded. can do.

It is sectional drawing which shows an example of the metal mold | die for glass molds of this embodiment. It is a flowchart which shows an example of the manufacturing method of the metal mold | die for glass molds of this embodiment. It is sectional drawing explaining the method of manufacturing an aspherical glass lens using the metal mold | die of FIG. It is a photograph of the sample for evaluation after a scratch test.

  A mode for carrying out the present invention will be described with reference to the drawings.

(Glass for glass mold)
In FIG. 1, an example of the metal mold | die for glass molds of this embodiment is shown. FIG. 2 shows an example of a method for producing a glass mold die according to the present embodiment.

  The mold 10 has a molding surface M for molding a glass material (for example, a low melting point glass) into an aspheric glass lens, and the first layer 12, the second layer 13, and the third layer 14 are formed on the base material 11. They are sequentially stacked.

  The base material 11 is made of a cemented carbide (WC-TiC-TaC alloy) and contains WC as a main component. Since the cemented carbide constituting the base material 11 is manufactured by sintering at a high temperature of approximately 1400 ° C., the carbonization of the components of the cemented carbide is saturated and the bond is estimated to be stable. That is, the cemented carbide constituting the base material 11 is an alloy having extremely few dangling bonds having radical bonding activity.

  Examples of commercially available cemented carbide include RCCFN (manufactured by Nippon Tungsten) and J05 (manufactured by Nippon Dice).

  The base material 11 can be produced by grinding and polishing a cemented carbide (S1).

  The first layer 12 is composed of one or more selected from the group consisting of tungsten carbide (WC), titanium carbide (TiC), and tantalum carbide (TaC), and can be formed by sputtering (S2). Among these, the first layer 12 is preferably a sputtered film containing WC. For example, when forming a sputtered film containing WC, a WC solid target is used as the WC source.

At this time, the sputtered film containing WC contains a cemented carbide component constituting the base material 11 and WC is a compound represented by a composition formula WC _1-x (x = 0 to 0.5). It is presumed that there is a radical binding activity during film formation. For this reason, it is estimated that the adhesion between the base material 11 and the second layer 13 is improved by the sputtered film containing WC.

  The thickness of the first layer 12 is preferably 1 to 50 nm, and more preferably 2 to 20 nm. When the thickness of the first layer 12 is 1 nm or more and 50 nm or less, the durability of the mold 10 is improved.

  The sputtering apparatus used for forming the first layer 12 is not particularly limited, and examples thereof include a magnetron sputtering apparatus.

  Examples of commercially available magnetron sputtering devices include a high-frequency sputtering device VTR-150M (manufactured by ULVAC).

  The second layer 13 is made of silicon carbide (SiC).

  The thickness of the second layer 13 is preferably 1 to 100 nm, and more preferably 5 to 30 nm. When the thickness of the second layer 13 is 1 nm or more and 100 nm or less, the durability of the mold 10 is improved.

The second layer 13 can be formed by plasma CVD (S3). At this time, SiC is presumed to be a compound represented by the composition formula SiC _1-x (x = 0 to 0.5), and is considered to have radical binding activity during film formation. For this reason, it is estimated that the second layer 13 has improved adhesion with the first layer 12 and the third layer 14.

  Although it does not specifically limit as a SiC source (raw material gas), Hydrocarbon gas etc. which contain Si, such as tetramethylsilane and siloxane, etc. are mentioned.

  Examples of commercially available plasma CVD apparatuses used for forming the second layer 13 include a plasma CVD apparatus CC-400 (manufactured by ULVAC) and a CVD apparatus PD-220N (manufactured by Samco).

  Note that the second layer 13 may be formed by sputtering or the like. In this case, a film is formed by a magnetron sputtering method using a SiC solid target.

  The third layer 14 is composed of diamond-like carbon (DLC).

DLC has an amorphous structure in which sp ² (graphite bond) and main component sp ³ (diamond bond) are mixed. For this reason, SiC that constitutes the second layer 13 and DLC that constitutes the third layer 14 adhere to each other due to a covalent bond in addition to van der Waals force. Si of SiC has four bonds of a covalent bond, also sp ³ of DLC principal components have four bonds, both bound form are similar. For this reason, it is speculated that the third layer 14 has good adhesion to the second layer 13.

  The third layer 14 preferably has silicon (Si) added to DLC. Thereby, the adhesion between the second layer 13 and the third layer 14 is further improved. Furthermore, since the heat resistance of the third layer 14 is improved, the durability of the mold 10 is further improved.

  The content of Si in the third layer 14 is preferably 0.1 to 10 mol%, and more preferably 2 to 8 mol%. When the content of Si in the third layer 14 is 0.1 mol% or more, the durability of the mold 10 is further improved, and when the content is 10 mol% or less, the mold 10 is released from the low melting point glass. Improves.

  The thickness of the third layer 14 is preferably 10 to 500 nm, and more preferably 50 to 250 nm.

  The third layer 14 can be formed by plasma CVD (S4).

  Although it does not specifically limit as a carbon source (raw material gas) of DLC, Hydrocarbon gas, such as acetylene, toluene, benzene, methane, and ethylene, is mentioned.

  Although it does not specifically limit as Si source (raw material gas), Hydrocarbon gas containing Si, such as tetramethylsilane and siloxane, etc. are mentioned.

  In addition, when using the hydrocarbon gas containing Si, it mixes with hydrocarbon gas and uses it as source gas.

  As a commercial product of the plasma CVD apparatus used for the film formation of the third layer 14, a DLC film formation apparatus NANOCOAT-500 (manufactured by Nanotech Co., Ltd.) and the like can be mentioned.

  Note that the first layer 12, the second layer 13, and the third layer 14 may be sequentially formed by providing a sputtering mechanism and a plasma CVD mechanism in the same chamber. Thereby, the productivity of the aspheric glass lens can be improved.

  Further, the third layer 14 may be formed by ion beam evaporation or the like.

  Since the mold 10 is excellent in durability even when an aspheric glass lens having a large diameter is manufactured, the productivity of the aspheric glass lens having a large diameter can be improved.

(Method of manufacturing an aspheric glass lens)
Next, a method for manufacturing an aspheric glass lens will be described with reference to FIG.

  For example, between the two molds 10, the low melting point glass G is heated and softened, and then press-molded to transfer the shape of the mold 10 to produce an aspheric glass lens. .

  Examples of commercially available low melting point glass G include low Tg optical glass for glass mold L-BAL43 (manufactured by OHARA), glass mold lens glass M-BACD12 (manufactured by HOYA), and the like.

  In addition, as long as it is a glass material which has a glass transition point, you may use materials other than low melting glass.

  Examples of commercially available press molding machines include a lens molding machine (manufactured by SYS) and a high-precision optical glass element molding apparatus GMP-311V (manufactured by Toshiba Machine Co., Ltd.).

  When a large-diameter aspheric glass lens is molded using the mold 10, an aspheric glass lens with a clear appearance can be easily obtained. This improves the yield (non-defective rate) of the appearance of the large-diameter aspheric glass lens. In addition, the process of polishing to clear the appearance, which is necessary when the appearance of the aspherical glass lens with a large diameter after molding has deteriorated due to spiders, etc., can be omitted, and productivity is improved. improves.

  The aspheric glass lens can be applied to an optical lens such as a camera lens or a projector lens.

  When the glass mold die of the present embodiment is used, in addition to the aspherical glass lens, it is possible to mold all glass material optical elements that are difficult to process by spherical polishing such as fθ lens, separator lens, and microlens.

  Examples of the present invention will be described below, but the present invention is not limited to these examples.

Example 1
A mold (see FIG. 1) was produced. The manufacturing process is described below.

  Cemented carbide RCCFN (manufactured by Nippon Tungsten Co., Ltd.) was ground and polished to prepare a base material 11.

  Base material 11 was placed in a vacuum chamber of high-frequency sputtering apparatus VTR-150M (manufactured by ULVAC). Next, the inside of the vacuum chamber was evacuated by a vacuum pump, and then the base material 11 was heated. Furthermore, after introducing Ar gas into the vacuum chamber, Ar ions ionized by the sputtering mechanism were applied to the surface of the base material 11 by applying an electric field, thereby cleaning the surface of the base material 11. Next, a 7 nm-thick WC film was formed as the first layer 12 by a sputtering mechanism. At this time, a WC solid target was used as the WC source.

  The base material 11 on which the first layer 12 was formed was placed in a vacuum chamber of a CVD apparatus PD-220N (manufactured by Samco). Next, the inside of the vacuum chamber was evacuated by a vacuum pump, and then the base material 11 on which the first layer 12 was formed was heated. Further, ions obtained by ionizing the source gas (tetramethylsilane) with a high-frequency electric field are drawn into the surface of the base material 11 on which the first layer 12 is formed, and a SiC film having a film thickness of 20 nm as the second layer 13 is drawn. A film was formed.

  In addition, after introducing Ar gas into the vacuum chamber in the stage before forming the second layer 13, Ar ions ionized by a high-frequency electric field are drawn into the surface of the base material 11, thereby forming the base material 11. The surface may be cleaned.

  The base material 11 on which the second layer 13 was formed was placed in a vacuum chamber of a DLC film forming apparatus NANOCOAT-500 (manufactured by Nanotech). Next, after evacuating the inside of the vacuum chamber with a vacuum pump, the base material 11 on which the second layer 13 was formed was heated. Further, after introducing the source gas (Ar) into the vacuum chamber, Ar ions ionized by the independent ion gun are applied to the surface of the base material 11 on which the second layer 13 is formed by applying a bias voltage. Thus, the surface of the base material 11 on which the second layer 13 was formed was cleaned. Next, an ion obtained by ionizing the source gas (toluene) with an independent ion gun is applied to the surface of the base material 11 on which the second layer 13 is formed by applying a bias voltage. Then, a DLC film having a thickness of 100 nm was formed to produce a mold.

(Example 2)
When the third layer 14 was formed, a mold was produced in the same manner as in Example 1 except that tetramethylsilane was mixed with the source gas toluene. At this time, when the content of silicon in the third layer 14 was measured using X-ray photoelectron spectroscopy, it was 7 mol%.

(Comparative Example 1)
Cemented carbide RCCFN (manufactured by Nippon Tungsten Co., Ltd.) was ground and polished to produce a base material 11.

  Base material 11 was placed in a vacuum chamber of high-frequency sputtering apparatus VTR-150M (manufactured by ULVAC). Next, the inside of the vacuum chamber was evacuated by a vacuum pump, and then the base material 11 was heated. Furthermore, after introducing Ar gas into the vacuum chamber, Ar ions ionized by the sputtering mechanism were applied to the surface of the base material 11 by applying an electric field, thereby cleaning the surface of the base material 11. Next, a SiC film having a thickness of 20 nm was formed as the second layer 13 by a sputtering mechanism. At this time, a SiC solid target was used as the SiC source.

  The base material 11 on which the second layer 13 was formed was placed in a vacuum chamber of a DLC film forming apparatus NANOCOAT-500 (manufactured by Nanotech). Next, after evacuating the inside of the vacuum chamber with a vacuum pump, the base material 11 on which the second layer 13 was formed was heated. Further, after introducing the source gas (Ar) into the vacuum chamber, Ar ions ionized by the independent ion gun are applied to the surface of the base material 11 on which the second layer 13 is formed by applying a bias voltage. Thus, the surface of the base material 11 on which the second layer 13 was formed was cleaned. Next, an ion obtained by ionizing the source gas (toluene) with an independent ion gun is applied to the surface of the base material 11 on which the second layer 13 is formed by applying a bias voltage. Then, a DLC film having a thickness of 100 nm was formed to produce a mold.

  Next, an aspheric glass lens was manufactured using the mold, and the durability of the mold and the appearance of the aspheric glass lens were evaluated.

(Production of aspherical glass lens)
An aspheric glass lens having a diameter of 50 mm was produced using a high-precision optical glass element molding apparatus GMP-311V (manufactured by Toshiba Machine Co., Ltd.) (see FIG. 3). Specifically, first, a low-Tg optical glass for glass mold L-BAL43 (manufactured by OHARA) as the low melting glass G was placed on the mold. Next, the inside of the vacuum chamber was evacuated by a vacuum pump and then purged with nitrogen gas. Further, the low-melting glass G was heated to about 570 ° C. by a heater mechanism, clamped, and press-molded to produce an aspheric glass lens.

(Durability of mold)
The durability of the mold was evaluated by determining the number of non-defective products that resulted in the occurrence of fine fusion resulting from the deterioration of the laminated film of the mold in the aspheric glass lens, that is, defective products.

(Appearance of aspheric glass lens)
The appearance of the aspheric glass lens was visually evaluated. In addition, when the appearance is clear, ○ (good product), when minor appearance defects such as spiders and minor fine fusion occur, △ (normal product), appearance defects such as fine fusion occur. The case was judged as x (defective product).

  Next, the adhesion strength of the laminated film in the evaluation sample corresponding to the mold was evaluated.

(Adhesion strength of laminated film)
A laminated film is formed on the substrate in the same manner as in Examples 1 and 2 and Comparative Example 1 except that a substrate made of cemented carbide RCFFN (manufactured by Nippon Tungsten) is used instead of the base material 11. An evaluation sample was produced.

  The adhesion strength of the laminated film in the sample for evaluation was measured using an ultra-thin scratch tester CSR1000 (manufactured by Reska).

  FIG. 4 shows a sample for evaluation after the scratch test. 4A, 4 </ b> B, and 4 </ b> C are evaluation samples after the scratch test of Examples 1 and 2 and Comparative Example 1, respectively. In the figure, the arrow is the starting point of the scratch.

  As shown in FIG. 4, in the samples for evaluation of Examples 1 and 2, since the second layer 13 is in close contact with the first layer 12, the film peels off near the interface between the base material 11 and the first layer 12. I understand that.

  On the other hand, in the sample for evaluation of Comparative Example 1, the second layer 13 is not tightly adhered to the first layer 12, so that it is torn at an angle near the interface between the second layer 13 and the first layer 12. The film is peeled off.

  Table 1 shows the evaluation results of the durability of the mold, the appearance of the aspheric glass lens, and the adhesion of the laminated film.

From Table 1, it can be seen that the molds of Examples 1 and 2 can mold an aspheric glass lens with a diameter of 50 mm that has a high durability and excellent appearance even if an aspheric glass lens with a diameter of 50 mm is molded. . For this reason, if the metal mold | die of Example 1, 2 is used, sufficient productivity can be ensured.

  In contrast, in the mold of Comparative Example 1, the first layer 12 including at least one selected from the group consisting of tungsten carbide, titanium carbide, and tantalum carbide is formed between the base material 11 and the second layer 13. As a result, the durability of the mold is reduced. This is because the base material 11 is manufactured by sintering and does not have radical binding activity, and most of the force acting between the base material 11 and the second layer 13 is only intermolecular force. This is probably because of this. For this reason, when the metal mold | die of the comparative example 1 is used, sufficient productivity cannot be ensured.

  In the molds of Examples 1 and 2, since the first layer 12 includes a cemented carbide component constituting the base material 11, adhesion between the base material 11 and the first layer 12 is improved. Moreover, since the metal mold | die of Example 1, 2 becomes easy to produce a chemical bond between the 2nd layer 13 by forming the 1st layer 12, compared with the metal mold | die of the comparative example 1, it is 1st. The adhesion between the layer 12 and the second layer 13 is greatly improved. In particular, by using the first layer 12 as a sputtered film, the radical bonding activity of the first layer 12 can be improved and the adhesion between the first layer 12 and the second layer 13 can be improved.

DESCRIPTION OF SYMBOLS 10 Mold 11 Base material 12 1st layer 13 2nd layer 14 3rd layer M Molding surface G Low melting glass

JP2011-98845A

Claims (6)

A first layer, a second layer, and a third layer are sequentially laminated on the base material,
The base material includes a cemented carbide,
The first layer includes one or more selected from the group consisting of tungsten carbide, titanium carbide, and tantalum carbide,
The second layer includes silicon carbide;
The glass mold is characterized in that the third layer contains diamond-like carbon.   The glass mold according to claim 1, wherein the first layer is a sputtered film containing tungsten carbide. The first layer has a thickness of 1 to 50 nm,
The second layer has a thickness of 1 to 100 nm,
The mold for a glass mold according to claim 1 or 2, wherein the third layer has a thickness of 10 to 500 nm.   The glass mold according to any one of claims 1 to 3, wherein the third layer further contains silicon, and the silicon content is 0.1 to 10 mol%. A method for producing a glass mold die according to any one of claims 1 to 4,
Forming the first layer using a sputtering method;
Using the plasma CVD method to form the second layer;
A method for producing a mold for glass mold, comprising a step of forming a film of the third layer using a plasma CVD method.   A method for producing an aspheric glass lens, wherein the glass mold die according to any one of claims 1 to 4 is used.