JPH01320233A - Dies for press-molding glass - Google Patents

Abstract

PURPOSE:To make post-machining such as polishing unnecessary after press molding by forming an SiC and/or Si3N4 film as an intermediate layer and a carbon film as a top layer on the face-shaped part of each glass base. CONSTITUTION:An SiC and/or Si3N4 film of <=1mum thickness as an intermediate layer 6 and a carbon film of <=1mum thickness as a top layer 7 are formed on the face-shaped part of each SiO2-based glass base 5 having a face shape corresponding to the shape of a press-molded glass product to be produced. The layers 6, 7 may be formed by sputtering or ion plating.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a mold for glass press molding, and in particular to a mold for obtaining a high-precision glass press molded product that does not require post-processing such as polishing after press molding. Regarding types.

[Prior art 1] As a mold for obtaining a glass press-molded product, a mold whose base material is glass whose glass transition temperature is higher than the pressing temperature of the glass to be molded is known. As a mold, Japanese Patent Laid-Open No. 62-226825 discloses a mold in which a melt-proof layer made of, for example, a carbon film is provided on a glass substrate in order to prevent the glass to be formed from being fused to the mold. It is being

[Problems to be Solved by the Invention] In the glass mold described in JP-A No. 62-226825, the carbon film serving as the anti-aging layer can be formed by a vacuum deposition method, a sputtering method, an ion blating method, etc. However, as a result of research by the present inventors, when a carbon layer is coated on a glass substrate, the adhesion of the carbon film to the substrate is poor;
It has become clear that the carbon film develops prickles over time, causing the following problems.

(2) The carbon film cannot function as a fusion prevention layer for a long period of time, and the life of the mold is short.

(f) Significant roughness occurs on the surface of the mold and the shape accuracy is impaired, making it impossible to obtain a desired glass press-molded product that has high surface accuracy and is optically free from defects.

Therefore, an object of the present invention is to provide a glass press molding mold that solves the problems (2) and (c) above by improving the adhesion of the carbon film to the base and preventing the carbon film from peeling off. There is a particular thing.

[Means for Solving the Problems] The present invention has been made to solve the above-mentioned problems, and the glass press molding mold of the present invention has silicon dioxide as a main component, and the glass to be manufactured. a glass substrate having a surface shape corresponding to the shape of the press-formed product; an intermediate layer comprising a silicon carbide and/or silicon nitride film provided at least on the surface shape portion of the glass substrate;
and an uppermost layer made of a carbon film provided on the intermediate layer.

The present invention will be explained in detail below.

The glass press molding mold of the present invention uses a glass base as a base, and the glass base has (1) silicon dioxide as a main component and (2) a surface corresponding to the shape of the glass press molded product to be manufactured. It has a shape.

First, examples of glasses that satisfy the condition (2) include quartz glass or glass containing 47 to 68% by weight of silicon dioxide as a first component and further 6 to 23% by weight of aluminum oxide as a second component. The latter glass containing silicon dioxide and aluminum oxide as essential components may optionally contain at least one of 19% by weight or less of zinc oxide, 18% by weight or less of magnesium oxide, and 13% by weight or less of boron oxide. Furthermore, small amounts of components such as calcium oxide, strontium oxide, barium oxide, lead oxide, alkali metal oxides, and fluorine can be contained.

The above-mentioned quartz glass has a glass transition temperature of about 1200°C and a thermal expansion coefficient of 5X10'/'C, while the above-mentioned glass containing silicon dioxide and aluminum oxide as essential components has a glass transition temperature of 600 to 800°C. , the coefficient of thermal expansion is 3
0X10' to 60X10'/''C, both glasses have high glass transition temperatures and low thermal expansion coefficients,
It is suitable as a base material for glass press molding molds.

Next, a glass base that satisfies the condition (■) can be formed by cold working the base material glass to give it a surface shape that corresponds to the shape of the glass press-molded product to be manufactured. In the case of a glass containing the above-mentioned silicon dioxide and aluminum oxide as essential components, it is preferable to form the glass by placing the thermally softened glass in a mold having a predetermined shape and press-molding it. The reason for this is that according to this method, the only mold that requires high-precision processing is the master mold, and by using this master mold, a large number of bases having a predetermined shape can be easily manufactured at low cost. Note that it is not necessary to form the entire base by the above-mentioned press molding of glass; instead, only a portion of the shape that corresponds to the molding surface of the mold is manufactured, and this is used to form other base portions (which may be made of glass or other materials other than glass). A glass substrate may be obtained by bonding with a glass substrate (which may be composed of a material such as

The glass press molding mold of the present invention has an intermediate layer made of at least silicon carbide and/or silicon nitride film on the surface-shaped portion of the glass base. The silicon carbide and/or silicon nitride film provided on the glass substrate is called an intermediate layer because, as will be described later, a top layer made of a carbon film is provided thereon to prevent the glass to be formed from fusing. This is because it will be done. According to the studies of the present inventors, this intermediate layer improves the adhesion between the glass substrate and the top layer and prevents the top layer from peeling, and as a result, the top layer acts as an anti-fusing layer. (f) The maximum surface roughness of the mold surface is kept low and the shape accuracy is high. It has become clear that, as a result, it is possible to obtain technical effects such as the ability to obtain a desired glass press-molded product with high surface precision and no optical defects.

The thickness of this intermediate layer is preferably 1 μm or less.

This intermediate layer made of silicon carbide and/or silicon nitride film is formed by a film forming method such as sputtering method, ion blasting method, plasma CVD method, or vacuum evaporation method.

When forming an intermediate layer made of a silicon carbide film by sputtering, the substrate temperature is 250 to 600°C, the RF power density is 3 to 15 W/ci, and the degree of vacuum during sputtering is 5X.
It is preferable to perform sputtering using the following combination of sputter target and sputter gas in the range of 10' to 5 x 10 -1 torr.

Target gas combination■ SiCARr or (Ar+82)■(SiC
+C)Ar or (Ar+)-12)■ S i
(CH4+ A r ) Furthermore, in order to form an intermediate layer made of a silicon nitride film by a sputtering method, the substrate temperature is 2.
50~600℃, RF power density 3~15W/cat,
Vacuum degree during sputtering: 5 x 10' to 5 x 1
It is preferable to perform sputtering using the following combinations of sputter targets and sputter gases in the range of 0-'torr.

Target gas combination■ 5i3Na Ar or (Ar+N2)■
When forming an intermediate layer consisting of a 3i N2 or (Ar+N2) silicon carbide film by the ion blasting method, the 3i ingot is melted and evaporated with an electron beam or the like, and then a hydrocarbon gas such as CH4 gas or the hydrocarbon gas is used. and Ar gas, and the degree of vacuum is 10.
It is preferable to activate the silicon carbide film through a glow discharge atmosphere of about -2 torr and MIWA the silicon carbide film on the substrate heated to 250 to 600°C. Note that instead of the glow discharge, the gas and the evaporated metal may be ionized by high frequency or the like.

To form an intermediate layer made of a silicon nitride film by the ion blating method, a Si ingot is melted and evaporated with an electron beam, and then a gas of N2 gas or a mixture of N2 gas and Ar gas is used, and the degree of vacuum is i. Activated through a glow discharge atmosphere of about o'torr,
Preferably, the silicon nitride film is bulk deposited on a substrate heated to 0-600°C. Note that instead of the glow discharge,
The gas and vaporized metal may be ionized by high frequency or the like.

When forming an intermediate layer made of silicon carbide film by plasma CVD method, DC plasma CVD, RF plasma CV
D. Methods such as microwave plasma CVD are effective.

Using silicon tetrachloride, propane, and hydrogen as raw material gases, base temperature 700-900℃, pressure 0, 1-300℃
Preferably, the silicon carbide film is deposited on the substrate in the torr range.

Similarly, DC plasma CVO is used to form an intermediate layer made of a silicon nitride film by plasma CVD.

Methods such as RF plasma CVD and microwave plasma CVD are effective, and silicon tetrachloride, ammonia, and hydrogen are used as raw material gases to coat the substrate at a substrate temperature of 700 to 900°C and a pressure of 0.1 to 10 torr. Preferably, a silicon nitride film is deposited.

When forming an intermediate layer made of a silicon carbide film by a vacuum evaporation method, a CO2 laser beam is tangentially applied to the outer peripheral surface of a silicon carbide sintered body rotating in a chamber evacuated to about 10-4 torr. It is preferable to irradiate the silicon carbide with a power density of about 104 W/cd to vaporize the silicon carbide and attach it to the opposing substrate. In addition, the base temperature is 2
The temperature is 50-600°C. Alternatively, a tablet of silicon carbide sintered body may be placed in a crucible, evaporated by an electron beam, and attached to a substrate heated to 250 to 600°C.

When forming an intermediate layer made of a silicon nitride film by a vacuum evaporation method, a CO2 laser beam is tangentially applied to the outer peripheral surface of a silicon nitride sintered body rotating in a chamber evacuated to about 10-4 torr. It is preferable to irradiate the silicon nitride with a power density of about 10'W/cm to vaporize the silicon nitride and deposit it on the opposing substrate. The base temperature is 25
The temperature is 0 to 600°C. In addition, a tablet of silicon nitride sintered body was placed in a crucible and evaporated with an electron beam.
It can also be applied to a substrate heated to 50-600°C.

Note that the intermediate layer may be formed of a mixture of silicon carbide and silicon nitride. Further, part of the intermediate layer can be made of a silicon carbide film, and the rest can be made of a silicon nitride film.

In the glass press molding mold of the present invention, a top layer made of a carbon film is provided on the above-mentioned intermediate layer as a layer for preventing the fusion of glass to be formed. Preferably, this top layer has a thickness of 1 μm or less.

The carbon film constituting the uppermost layer is formed by a sputtering method, a plasma CVD method, a CVD method, a vacuum evaporation method, an ion blating method, or the like.

When forming a carbon film by sputtering, the substrate temperature is 250 to 600°C, and the RF power density is 5 to 15 W/
cIi, degree of vacuum during sputtering 5 x 10 ~ 5 x 1
It is preferable to perform sputtering using an inert gas such as Ar as a sputtering gas in the range of 0-1 torr and using graphite as a sputtering target.

When forming a carbon film by the microwave plasma CVD method, the substrate temperature is 650 to 100°C, the microwave power is 200W to IKW, and the gas pressure is 10-2 to 60Q to
It is preferable to form a film using methane gas and hydrogen gas as raw material gases at the start of forming the rr strip.

When forming a carbon film by a vacuum evaporation method, it is preferable to evaporate the carbon rod by arc discharge in a vacuum.

When forming a carbon film by an ion blating method, it is preferable to ionize benzene gas.

A glass press molding mold basically consists of an upper mold, a lower mold, and a guide mold that slidably accommodates the upper and lower molds, but the upper mold is composed of a glass base, an intermediate layer, and a top layer. They are a mold and a lower mold, and the guide mold may be made of a normal material such as a silicon carbide sintered body. Further, it is not necessary that the entire upper mold and lower mold have a three-layer structure, and only the glass molding surface can have a three-layer structure.

Further, the intermediate layer of either the upper mold or the lower mold may be a silicon carbide film, and the other intermediate layer may be a silicon nitride film.

[Function] The glass press molding mold of the present invention has an intermediate layer made of silicon carbide or silicon nitride film interposed between the glass base and the top layer made of carbon film, and the middle layer is made of glass. Since it has affinity for both the substrate and the top layer made of carbon film, the adhesion between the glass substrate and the top layer made of carbon film is significantly improved.

[Example] The present invention will be explained in detail below.

Example 1 An example of a glass press molding apparatus including a mold of the present invention is shown in FIG. In Figure 2, the molds are upper mold 1 and lower mold 2.
and a guide mold 3, and the upper mold 1 and the lower mold 2 are the guide mold 3.
A glass gob 4 to be molded is set between the upper mold 1 and the lower mold 2.

As shown in FIG. 1, the upper mold 1 and the lower mold 2 have a middle cylinder layer 6 made of a silicon carbide film on a surface shaped portion of a glass base 5 corresponding to the shape of the glass press-molded product to be manufactured. On this intermediate layer 6, a top layer 7 made of a carbon film is provided as a layer for preventing fusion of the glass to be formed. Here, as the glass substrate 5, the raw material composition is % by weight.
5iO257,01AI20316.0, ZnO6,
0,MQO9,0,82037,0°Na2O1,01
cao 1.0. BaO2,0, pbo i,o,
Consisting of K2O1,o, outer diameter 14. w, glass with a height of about 7 um (transition temperature 690 °C, coefficient of thermal expansion 38 x 10-7
/'C) was precision processed and finished into an optical mirror surface. Further, an intermediate layer 6 made of a silicon carbide film on this substrate 5 was formed by a sputtering method under the following conditions, and the film thickness was 1000.

Sputtering method group for forming intermediate layer 6! l! Humidity: 300°C RF power density: 5 W/i Vacuum level: 5 x 10-3 torr Target: SiC Sputtering gas: Ar Furthermore, the top layer 7 on the intermediate layer 6 was formed by sputtering under the following conditions, and its film thickness was 500 mm. Ta.

Sputtering method conditions for forming the top layer 7 Base temperature
300°C RF power density 9 W/cji Vacuum degree 5 X 10-3 torr Target C Sputtering gas Ar Next, using the upper mold 1 and lower mold 2 having the above three-layer structure,
Further, a mold was constructed using a silicon carbide sintered body as the guide mold 3, and glass was press-molded using the mold in the following manner. That is, optical glass 5F15 containing a large amount of PbO is placed in the mold as the glass to be molded.
<Transition temperature 445℃, coefficient of thermal expansion 82 x 10”7/
"C1 refractive index nd 1.70) glass lump 4 is put in,
Placed on the support rod 9 via the support stand 10, heated the glass gob 4 together with the mold by the heater 12 wrapped around the outer periphery of the quartz tube 11 in an N2 atmosphere, and lowered the push rod 13. At 520℃, 50? (Pressed for 30 seconds at a pressure of y/crn2. After that, the pressure was released, and the obtained glass press molded product was slowly cooled to the above transition temperature while in contact with the upper mold 1 and lower mold 2, and then at room temperature. The glass press-molded product was then rapidly cooled to a temperature close to that of the original temperature, and the glass press-molded product was taken out from the mold.

The surface shapes of the upper and lower molds were directly transferred to this glass press-molded product, and the lens had high surface viscosity, was not fused to the mold, and no optical defects were observed.

When this molding operation was continued, a slight roughness appeared on the top layer after about 500 times, but after 10
It was found that it could withstand use up to 00 times. 1000
After repeated molding, the uppermost carbon film was removed by oxygen plasma ashing, and the outermost surface layer of the intermediate layer was reverse sputtered, and then the uppermost layer was formed again and used for subsequent press molding.

Example 2 As a base material, the raw material composition is 5io257.0 in weight%
, Al20312.0. ZnO10゜0, It/100
Glass consisting of 6.0, CaO10,0, PbO3,0 (transition temperature 730"C1 thermal expansion coefficient 43x10'/℃
), and when the glass is thermally softened, it is placed in a mold with the desired surface shape and heated with inert gas (N2).
Press temperature 850℃ in atmosphere, press pressure! 50K
Press molding was performed for 30 seconds at 9/c 2 to obtain a base 5 for the upper mold 1 and the lower mold 2.

Next, on this substrate 5, an intermediate layer 6 consisting of a 500-layer silicon carbide film was formed by an ion blasting method under the following conditions.

Ion Blating Method for Forming Intermediate Layer 6 Color and Substrate Temperature: 500°C Evaporated Metal: 3i Degree of Vacuum: 5 x 10-2 torr Reactive Gas: CHa + Ar Electron Beam: 10 KV, Power of 400 to 450 mA Further, on this intermediate layer 6, 1000 people The uppermost layer 7 consisting of a carbon film was formed by microwave plasma CVD under the following conditions.

Micro plasma CVD method conditions for forming the top layer 7 Base temperature: 700°C Raw material gas: Methane + hydrogen 100 cc/min Methane concentration (CH4/CH4 + H2): 8mo1% Microwave power: 500W Reaction time: 90 minutes As a result of assembling a mold using an upper mold 1 and a lower mold 2 consisting of an intermediate layer 6 and a top layer 7 and performing press molding of glass, no change was observed in the mold even after 3000 press moldings. A glass press molded product with a high area density was obtained.

Example 3 As the base material, quartz glass (transition temperature: 1200°C)
This was cold-worked to form a base 5 having the same shape as in Example 1.

Next, on this substrate 5, an intermediate layer 6 consisting of a 3000 silicon nitride film was formed by a plasma CVD method under the following conditions.

Plasma CVD method conditions raw material gas for forming the intermediate layer 6
Silicon tetrachloride, nitrogen, hydrogen Reaction temperature: 800° C. Reaction time: 20 minutes Further, on this intermediate layer 6, a top layer 7 consisting of a 3,000-layer carbon film was formed by microwave plasma CVD method under the following conditions.

Micro plasma CVD method conditions for forming the top layer 7 Base temperature 900℃ Raw material gas Methane + hydrogen 150CC/Win methane 1
1 degree (CH4/CH4+H2) i51101% Microwave power 550W Reaction time 40 minutes Obtained "L" consisting of base 5, middle layer 6 and top layer 7
As a result of assembling a mold using mold 1 and lower mold 2 and press-molding glass, the same results as in Example 2 were obtained.

Example 4 Using quartz glass as the base material, an intermediate layer was formed under the same conditions as in Example 1, and an uppermost layer was formed in the same manner as in Example 3. As a result of press molding the glass, the same results as in Example 2 were obtained.

Effect of Light] As described above, the glass press molding mold of the present invention has the following effects:
The excellent adhesion between the glass base and the top layer made of carbon film prevents the top layer from peeling off, allowing the top layer to function as a prevention layer for glass to be formed over a long period of time. This makes it possible to prolong the life of the mold and is economical.

Further, since the maximum surface roughness of the mold surface of the mold can be kept low and the shape accuracy can be kept high, it is possible to obtain a glass press-molded product that has high surface accuracy and is optically free from defects.

[Brief explanation of the drawing]

FIG. 1 is a partial view of a glass press molding mold of the present invention, and FIG. 2 is a schematic diagram of a glass press molding Qll including the glass press molding mold of the present invention. 1... Upper mold, 2... Lower mold, 3... Guide mold, 4...
・Glass lump, 5... Glass base, 6... Intermediate layer, 7
...Top layer, 9...Support rod, 10...Support stand, 1
1...Quartz tube, 12...Heater, 13...Push rod, 14...Thermocouple.

Claims (1)

[Claims] 1. A glass substrate containing silicon dioxide as a main component and having a surface shape corresponding to the shape of the glass press molded product to be manufactured, and silicon carbide and/or silicon carbide provided at least on the surface shape portion of the glass substrate. Alternatively, a glass press molding mold comprising an intermediate layer made of a silicon nitride film and an uppermost layer made of a carbon film provided on the intermediate layer.