JP2742362B2 - Glass press mold - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a glass press mold, and more particularly to a glass press mold used for manufacturing a glass molded article such as a glass lens.

[0002]

2. Description of the Related Art In the production of glass lenses by press molding, especially when it is desired to eliminate the need for cold polishing after press molding, the surface shape of the glass lens is transferred as it is at high temperatures. In addition, the surface of the mold must have sufficient surface accuracy and surface roughness required for the glass lens surface. For this reason, glass press molds do not cause chemical reaction with glass at high temperatures, have excellent oxidation resistance and heat resistance, have high hardness and do not undergo structural change or plastic deformation during press molding, and furthermore, molds It is required that the shape has good workability and the frictional resistance of the mold surface is as small as possible.

Conventionally, as a glass press mold, tungsten carbide (WC), silicon nitride (S)
i ₃ N ₄ ), silicon carbide (SiC) and the like are used. However, in any of these, high-temperature press of 400 ° C. or more causes fusion of glass to the mold surface by several to several tens of presses. In order to prevent this, it is known to provide a mold release film made of carbon on a mold surface. Examples of a means for forming a carbon release film include a method of forming a hard carbon film on a mold surface using a sputtering gas of argon and a sputter target of graphite by a sputtering method to form a glass press mold (Japanese Patent Laid-Open No. 1-83529), Japanese Patent Application Laid-Open No. 2-199036 discloses a method in which hydrocarbon ions are generated by an ionization source consisting of an anode electrode and a cathode electrode by an ion plating method to form an i-carbon film on the surface of a mold to form a glass press mold. ).

[0004]

The hard carbon film obtained by the conventional sputtering method is excellent in heat resistance and releasability, but since it contains amorphous graphite, the press molding temperature is particularly 600 ° C. When the pressing operation is repeated a number of times at the above high temperature, a part of the film may be peeled off.

[0005] The i-carbon film obtained by the ion plating method has excellent heat resistance, oxidation resistance and adhesion to the substrate, and does not easily fuse glass at the time of molding. In addition, since the film surface in contact with the glass has high smoothness, gas released from the glass surface is trapped between the glass surface and the film surface during press molding, and minute recesses are generated on the surface of the formed glass. There is.

An object of the present invention is to provide a glass press mold having a release film made of a hard carbon film obtained by the above-described sputtering method and a release mold made of an i-carbon film obtained by an ion plating method. An object of the present invention is to provide a glass press mold that eliminates the above-mentioned disadvantages that occur in a glass press mold having a film.

[0007]

DISCLOSURE OF THE INVENTION The present invention has been made to achieve the above-mentioned object, and has been made in a molding die for press-molding glass. A glass press mold characterized by having a carbonaceous two-layer structure film formed by sequentially laminating an i-carbon film and a hard carbon film on a work surface on a mold base machined into a corresponding shape. And

Hereinafter, the present invention will be described in detail. In the glass press mold of the present invention, the base is processed into a shape corresponding to the shape of the glass molded body to be obtained by molding. It is natural that the substrate is processed into such a shape because a thin release film is provided on the substrate to conform to the shape of the substrate to form a glass press mold. As the base material, silicon (Si), silicon nitride (Si ₃ N ₄ ), tungsten carbide (WC),
Alumina (Al ₂ O ₃ ) and titanium carbide (TiC)
Although a cermet or the like is also used, it is preferable to use a silicon carbide (SiC) sintered body. It is particularly preferable that the silicon carbide sintered body has a silicon carbide film formed by a CVD method on a surface in contact with glass during press molding.

The glass press mold of the present invention has a carbonaceous two-layer structure film in which an i-carbon film and a hard carbon film are sequentially laminated on the processed surface on the base. Preferably, the i-carbon film is formed by ion plating, and the hard carbon film is formed by sputtering.

First, the formation of an i-carbon film by the ion plating method will be described. The ion plating method includes an anode electrode, a first cathode electrode, and a base holder for holding a base of a glass press mold, and further includes a reflector arranged so as to surround the first cathode electrode and the anode electrode. This is performed using an ion plating apparatus. In this ion plating apparatus, a low voltage of 50 to 150 V is applied between the anode electrode and the first cathode electrode to generate a plasma of hydrocarbon ions. When the low voltage is less than 50 V, the ionization efficiency is low and inefficient, and when the voltage exceeds 150 V, the plasma becomes unstable.
To 150 V) is preferred.

The hydrocarbon used preferably has a ratio of the number of carbon atoms to the number of hydrogen atoms (C / H) of 1/3 or more. As an example, benzene (C / H =
6/6), toluene (C / H = 7/8), xylene (C
/ H = 8/10), acetylene (C
/ H = 2/2), methylacetylene (C / H = 3 /
4), unsaturated hydrocarbons containing a triple bond such as butyne (C / H = 4/6), ethylene (C / H = 2/4), propylene (C / H = 3/6), butene (C / H = 4/8) and other double bond-containing unsaturated hydrocarbons, ethane (C / H = 2 /
6), propane (C / H = 3/8), butane (C / H =
4/10) and pentane (C / H = 5/12). These hydrocarbons may be used alone or as a mixture of two or more.

On the other hand, methane having a C / H of less than 1/3 (C / H = 1/4), acetone, acetic acid, alcohols (methanol, ethanol, propanol, etc.), dioxane, aniline, pyridine, etc. Hydrocarbon compounds containing oxygen or nitrogen may not be suitable for use because at least one of the film formability of the release film and the release property of the press-formed product during press molding is insufficient. It is known.

Further, 0.5 to 2... So that the substrate holder becomes the second cathode electrode with respect to the anode electrode.
A voltage of 5 kV is applied to accelerate the acceleration of hydrocarbon ions. Outside this voltage range, acceleration of hydrocarbon ions is insufficient at less than 0.5 kV, the adhesion between the glass press mold base and the i-carbon film becomes weak, and abnormal discharge occurs at more than 2.5 kV. This is because it becomes easier.

The substrate temperature during the ion plating process is preferably from 200 to 400 ° C. The reason is that the film quality of the i-carbon film formed at a temperature lower than 200 ° C. is weak, and the i-carbon film floats in a film form from the surface of the substrate immediately after the temperature is raised in a heating and holding test at 650 ° C. in a nitrogen atmosphere. This is because, while the heat resistance in the upward direction is inferior, at 200 to 400 ° C., no change is exhibited even after holding for 30 hours in the same heat holding test as described above.

The practical range of the thickness of the i-carbon film is 50 to
When the thickness is less than 50 Å, it is difficult to form a uniform film,
Above 00 Å, mold release occurs due to strain in the film. Further, from the viewpoint of increasing the adhesion of the hard carbon film and protecting the surface of the base material, which is the purpose of the i-carbon film formation, the thickness of the i-carbon film is relatively thin and sufficient, and therefore, A preferred range is 100 to 1,000 angstroms.

Next, the i-
The film formation on the carbon film will be described. The sputter method is carried out using a substrate holder for holding a press-molding die substrate on which an i-carbon film has been formed by the above-described ion plating method, and a sputter apparatus for accommodating a sputter target facing the substrate holder. In this sputtering apparatus, the substrate temperature is preferably from 250 to 450 ° C. The reason is that when the temperature exceeds 450 ° C., the surface roughness of the formed film surface rapidly deteriorates, and when the temperature is lower than 250 ° C., the film hardness decreases, so that any of them is unsuitable as a release film. . In this sputtering method, it is preferable to form a hard carbon film by generating plasma by high frequency using argon gas as a sputtering gas and graphite as a sputtering target.

The practical range of the thickness of the hard carbon film is determined by the aforementioned i.
-50 to 5,000 angstroms like the carbon film, but the i-carbon film is an intermediate medium with the hard carbon film, whereas the purpose of the hard carbon film formation is From the viewpoint of ensuring the quality of the surface of the glass to be formed, the necessary minimum thickness is good, so the preferable range is 100 to 2,000 angstroms.

The above-mentioned i-carbon film and hard carbon film may be formed by an independent ion plating apparatus and a sputter apparatus, respectively. It is preferable to use an apparatus that satisfies both the functions of the sputtering method and the sputtering method.

[0019]

The glass press mold of the present invention has an i.
-A carbon film and a hard carbon film are sequentially provided,
Although a layer structure film is formed, an i-carbon film having good adhesion to the base is interposed between the base and the hard carbon film by such a structure. Are firmly bonded, and peeling of the film that occurs when a hard carbon film is directly provided as a release film on the substrate is prevented. Further, since the i-carbon film does not directly contact the glass, the problem of the formation of the concave portion of the glass molded body which occurs when the release film is the i-carbon film is also solved. In addition, the characteristics of the hard carbon film as a release film can be fully exhibited.

As described above, the glass press mold of the present invention compensates for the respective disadvantages of the i-carbon film and the hard carbon film, and provides high adhesion to the substrate of the i-carbon film.
Combines the advantages of high hardness, oxidation resistance and the releasability of the hard carbon film.The hard carbon film is hard to peel off even if glass press molding is repeated many times, and the glass releasability is good. Therefore, a high quality glass molded body can be repeatedly produced many times over a long period of time.

[0021]

The present invention will be further described with reference to the following examples. [Example 1] A silicon carbide (SiC) sintered body was used as a base material of a glass press forming die, and after processing into a press forming die shape by grinding, a silicon carbide film was further formed on the processing surface side by a CVD method and further ground. And a mirror-finished shape corresponding to the molded body to be manufactured by polishing was obtained to obtain a molding die base.
Next, an i-carbon film was formed on the silicon carbide film on the mold base by an ion plating method. FIG. 1 shows i-
FIG. 2 is a schematic diagram of an ion plating apparatus used for forming a carbon film. In the ion plating apparatus shown in FIG. 1, a base holder 12 having a built-in heater 19 is provided above a vacuum chamber 11, A mold base 13 having a silicon film is held. A first cathode electrode 14 made of a tantalum (Ta) filament and an anode electrode 15 made of a tungsten (W) base are installed at a lower portion facing the base holder 12, and a cylindrical shape surrounding both the electrodes 14, 15 is provided. A reflector 16 is provided, which aims to concentrate the generated ions in the direction of the substrate 13. In the figure, reference numeral 17 denotes an inlet for introducing argon and benzene, and reference numeral 18 denotes an exhaust port for evacuation.

After the degree of vacuum in the vacuum chamber 11 is evacuated to 5.0 × 10 ⁻⁶ Torr from the exhaust port 18,
7. The degree of vacuum is increased by introducing more argon gas.
0 × 10 ⁻⁴ Torr and the first cathode electrode 14
A voltage of 80 V was applied between the cathode electrode and the anode electrode 15, plasma was generated during this time, and the argon gas was ionized by thermoelectrons from the first cathode electrode 14. Further, the second cathode electrode, ie, the base holder 12 and the anode electrode 1
A voltage of 1.5 kV was applied between 5 and a voltage of 80 V was applied to the reflector 16, and argon ions were intensively accelerated on the substrate 13, thereby ion bombarding and cleaning the surface of the substrate 13. Heating of the mold base 13 is not necessarily required in the ion bombardment step, but it is preferable to heat the mold base 13 in consideration of promoting the cleaning effect of the mold surface and heating in the subsequent film forming step.

Next, the vacuum chamber 11 is evacuated again, and benzene gas is introduced through the gas inlet 17 to maintain the degree of vacuum at 2.0 × 10 ⁻³ Torr. The benzene gas is converted into hydrocarbon ions by applying a voltage of 80 V between the substrate holder 12 and the base electrode 12 which is the second cathode electrode and the anode electrode 1.
A voltage of 1.5 kV is applied between 5 and a voltage of 80 V is applied to the reflector 16 to accelerate the hydrocarbon ions intensively in the direction of the mold base 13.
On the surface of the mold base 13 heated to 700 ° C.
An Angstrom i-carbon film was formed.

FIG. 2 is a schematic view of a sputtering apparatus used for forming a hard carbon film on the i-carbon film by a sputtering method. In the sputtering apparatus shown in FIG. 2, a substrate holder 22 having a built-in heater is provided above a vacuum chamber 20, and a mold substrate 21 already covered with an i-carbon film is held. Furthermore, a target 23 made of graphite is arranged below the vacuum chamber 20 so as to face the mold base 21. In the figure, 24 is a magnet, 25 is an RF power source, and 13.
It is a high frequency of 56 MHz, 26 is an inlet for argon gas, and 27 is an exhaust port for vacuum exhaust.

After the degree of vacuum in the vacuum chamber 20 is evacuated to 5.0 × 10 ⁻⁵ Torr by the exhaust port 27,
4. The degree of vacuum is increased by introducing more argon gas.
The graphite target 23 was sputtered by applying high-frequency power from the RF power supply 25 while maintaining the pressure to 0 × 10 ⁻³ Torr, and the film was formed on the i-carbon film of the mold base 21 previously heated to 300 ° C. A hard carbon film having a thickness of 700 angstroms was formed.

In this manner, as shown in FIG. 3, silicon carbide film 2 formed by the CVD method is formed on the press-formed surface of silicon carbide sintered body 1 having a predetermined shape. 2, an i-carbon film 3 is formed by an ion plating method, and a hard carbon film 4 is further formed on the i-carbon film 3 by a sputtering method. Was.

Next, the results of press molding using the glass press mold obtained in this example are shown below. As shown in FIG. 3, a glass 7 made of glass A (glass transition point temperature: 475 ° C.) is placed between a pair of glass molds 5, 5 and a guide mold 6, and then the glass 7 is heated to a temperature of 54 in a nitrogen atmosphere.
5 ° C. at (corresponding to a glass viscosity of 10 ⁹ poises) 50 kgf
The molding was carried out for 60 seconds at a press pressure of / cm ^{2 and} the operation of rapidly cooling to room temperature was repeated. As a result, the press mold of this example (five mold samples obtained by the same method were used. The same applies hereinafter). ), No glass fusion was observed even after 1000 times of press molding, and the surface of the hard carbon film did not show any deterioration (see the results of glass A in Example 1 in Table 1).

When a glass B (glass transition temperature 545 ° C.) different from the above glass was press-formed at a temperature of 650 ° C. under the same conditions as above, five press-molding dies of this embodiment were used. Two of the mold samples were 893 and 9
On the fifteenth time, traces of local peeling of the hard carbon film were confirmed on the surface of the glass to be molded, but no fusion of the glass was observed, and press molding could be continued. The remaining three mold samples did not change even after 1000 times of press molding (see the results of glass B in Example 1 in Table 1). On the other hand, the molding surface on which the i-carbon film and the hard carbon film are not formed is a silicon carbide film. In the mold of the reference example, the glass A is 5 to 9 times, and the glass B is 2 to 3 times. Fusing occurred, and the surface of the glass to be formed corresponding to the fused portion was confirmed to be rough (see the results of glass A and glass B in Reference Examples in Table 1).

Example 2 The same experiment as in Example 1 was performed except that only the thicknesses of the i-carbon film and the hard carbon film were changed. That is, the degree of vacuum is set to 2.0 × 10 ⁻³ Torr by benzene gas, the substrate temperature is 300 ° C., the voltage between the anode electrode and the first cathode electrode is 80 V, and the voltage between the substrate holder (second cathode electrode) and the anode electrode is After forming an i-carbon film of 200 angstroms on the surface of the mold base at a voltage of 1.5 kV, the degree of vacuum was 5.0 × 10 ⁻³ Torr by argon gas on the i-carbon film.
r, a graphite target was sputtered at a substrate temperature of 300 ° C. while applying high-frequency power to form a 200 Å hard carbon film. Next, press molding was performed in the same manner as in Example 1 using the glass press molding die obtained in this example.
At the 34th time, traces of local exfoliation of the hard carbon film were confirmed on the surface of the glass to be molded, but fusion of the glass was not observed, and press molding could be continued (see Example 2 in Table 1). See results for glass A). In the case of glass B different from glass A, the same results as glass A were confirmed 693-785 times (see the results of glass B in Example 2 in Table 1).

Example 3 As in Example 1, the degree of vacuum was set to 2.0 × 10 ⁻³ Torr by benzene gas, the substrate temperature was 300 ° C., the voltage between the anode electrode and the first cathode electrode was 90 V, and the substrate was A voltage of 1.5 kV between the holder (second cathode electrode) and the anode electrode is applied to the surface of the mold base as 1.5 kV.
After forming an i-carbon film of 2,000 Å, a vacuum degree of 5.0 × 10 ⁻³ Torr was applied to the i-carbon film with argon gas, a graphite target was applied at a substrate temperature of 300 ° C., and high-frequency power was applied. Sputtering was performed to form a 2000 Å hard carbon film. Next, press molding was performed using the glass press mold obtained in this example in the same manner as in Example 1, and as a result, no fusion of glass was observed even with glass A and glass B even 1000 times. The surface of the carbon film did not show any deterioration (see the results of glass A and glass B in Example 3 in Table 1).

Example 4 As in Example 1, the degree of vacuum was set to 2.0 × 10 ⁻³ Torr by benzene gas, the substrate temperature was 300 ° C., the voltage between the anode electrode and the first cathode electrode was 90 V, and the substrate was After forming an i-carbon film of 100 angstroms on the surface of the mold base at a voltage of 1.5 kV between the holder (second cathode electrode) and the anode electrode, the degree of vacuum was adjusted to 5.degree. A graphite target was sputtered at 0 × 10 ⁻³ Torr at a substrate temperature of 300 ° C. while applying high-frequency power to form a hard carbon film of 100 Å. Next, as a result of performing press molding using the glass press mold obtained in this example in the same manner as in Example 1, the glass A was hardened 754 to 815 times, and the glass B was hardened 543 to 597 times. Although local traces of peeling of the carbon film were confirmed on the surface of the glass to be molded, fusion of the glass was not observed and press molding could be continued (glass A and glass B in Example 4 in Table 1). Results).

Comparative Example 1 A comparative experiment with Example 1 was performed using a comparative mold having an i-carbon film on a substrate but not forming a hard carbon film. That is, the degree of vacuum is 2.0 × 10 ⁻³ Torr by benzene gas, the substrate temperature is 300 ° C., the voltage between the anode electrode and the first cathode electrode is 80 V, and the voltage between the substrate holder (second cathode electrode) and the anode electrode is At a voltage of 1.5 kV, an i-carbon film of 700 Å was formed on the surface of the mold base to obtain a glass press mold. Next, as a result of performing press molding using this glass press mold in the same manner as in Example 1, in the case of glass A, no fusion was performed from the 43rd to 52nd times, but fine recesses were generated on the surface of the molded glass. (See the results of glass A in Comparative Example 1 in Table 1). In the case of glass B different from the above glass,
The same result as that of glass A was confirmed from the 19th to 34th times (see the results of glass B in Comparative Example 1 in Table 1).

Comparative Example 2 A comparative experiment with Example 1 was performed using a comparative mold having a hard carbon film formed thereon without forming an i-carbon film on a substrate. That is, a graphite target was sputtered at a substrate temperature of 300 ° C. by applying high-frequency power at a substrate temperature of 300 ° C. to form a hard carbon film of 700 angstrom with an argon gas at 5.0 × 10 ⁻³ Torr. Next, press molding was performed using this glass press mold in the same manner as in Example 1, and as a result, glass fusion was observed 203 to 302 times for glass A and 153 to 252 times for glass B. (See the results for glass A and glass B in Comparative Example 2 in Table 1).

[0034]

[Table 1]

[0035]

According to the present invention, an i-carbon film and a hard carbon film are sequentially provided on a substrate to form a carbonaceous two-layer structure film, that is, between the substrate and the hard carbon film. By interposing the i-carbon film having good adhesion to the substrate, a glass press mold in which the substrate and the hard carbon film are firmly bonded can be obtained.

The glass press mold of the present invention mutually compensates for the respective disadvantages of the i-carbon film and the hard carbon film,
It has the advantages of high adhesion to the substrate of the i-carbon film, high hardness, oxidation resistance and the releasability of the hard carbon film. Even if the glass press molding is repeated many times, the hard carbon film Is difficult to peel off and has good glass release properties.
High quality glass molded articles can be repeatedly produced many times over a long period of time.

[Brief description of the drawings]

FIG. 1 is a schematic view of an ion plating apparatus for forming a film based on an i-carbon film.

FIG. 2 is a schematic view of a sputtering apparatus for forming a hard carbon film on an i-carbon film.

FIG. 3 is a view showing an example of glass press molding using the press mold of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Sintered silicon carbide, 2 ... Silicon carbide film, 3 ... I-carbon film, 4 ... Hard carbon film, 5 ... Glass forming die, 6 ... Guiding die, 7 ... Glass to be formed, 11 ... Vacuum tank, 12 ... Base holder, 13 ... Glass mold base, 14 ... Cathode electrode,
15 ... Anode electrode, 16 ... Reflector, 17 ... Gas inlet, 18 ... Exhaust port, 19 ... Heater, 20 ... Vacuum tank, 21 ... Glass mold base, 22 ... Base holder, 2
3 ... graphite target, 24 ... magnet, 25
... RF power supply, 26 ... Gas inlet, 27 ... Exhaust.

Claims (4)

(57) [Claims] 1. A molding die for press-molding a glass, an i-carbon film and a hard film are formed on a processing surface on a molding die substrate processed into a shape corresponding to a shape of a glass molded product to be obtained by molding. A carbonaceous material obtained by sequentially laminating carbon films.
A glass press mold having a layered film. 2. The substrate according to claim 1, wherein a silicon carbide film is formed on the sintered silicon carbide base material by a CVD method.
2. The glass press mold according to 1. 3. An i-carbon film having a thickness of 50 to 5,000.
2. The glass press mold according to claim 1, wherein the glass press mold has a thickness of 0 Å. 4. The glass press mold according to claim 1, wherein the hard carbon film has a thickness of 50 to 5,000 angstroms.