JPS63297231A - Molding mold for glass product - Google Patents

Abstract

PURPOSE:To obtain a press molding mold for an optical component being excellent in mold release properties to a glass and easy in processing, by forming the molding mold with the glass or glass ceramic containing nitrogen and fluorine. CONSTITUTION:The aimed molding mold consisting of a glass or glass ceramic containing nitrogen and fluorine. The molding mold is excellent in mold release properties to a glass product to be molded because of containing nitrogen and fluorine and excellent in shape reproducibility, because the coefficient of thermal expansion exhibits linearity. Such a mold contains nitrogen and fluorine having inferior affinity with an oxide and is formed from a glass or glass ceramic exhibiting diversing higher than molding temperature of the glass product to be molded and mirror polishing is applied to desired shape in the press molding face.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is a mold for press molding optical parts, particularly for molding optical elements such as lenses and prisms made of glass or plastic, or cover glasses for watches. This relates to a mold for molding.

[Prior Art] It is known from Japanese Patent Publication No. 55-11624 that glass is formed into a predetermined molded product by hot pressing. Shape and surface properties have not been achieved.

This is because the mold releasability largely depends on the wettability of the glass resulting from the material of the press mold.

Recently, the use of molds made of glassy carbon, tungsten alloys or quartz glass has been proposed in US Pat. No. 4,098,599.
No. 6 and Dutch Patent No. gQO 30, and US Pat. No. 316,861 discloses the use of a mold made of 5US400 stainless steel.

[Problem to be Solved by the Invention 1] However, these conventional molds have the following problems. For example, in metals such as stainless steel, crystal grains and the like grow due to temperature cycles during glass forming and hot working, changing the crystal structure, resulting in a rough surface. This has the drawback of deteriorating the surface shape and mold releasability, impairing the smoothness and gloss of the crystal in the early stage of molding, and extremely shortening the life of the mold.

Glassy carbon, on the other hand, is easily oxidized, structurally weak, susceptible to surface scratches, and has low fracture impact resistance.

All of these properties are undesirable for heat-softening and pressure-forming glass. Furthermore, 1. Since quartz glass has wettability and low thermal conductivity, it is not sufficient as a mold material like glassy carbon, and according to the applicant's research, it has particularly good high-temperature oxidation resistance and mold release properties. There was nothing better.

In order to eliminate these drawbacks, S is applied to the press molding surface of the mold body made of a metal base material such as stainless steel by PVD (physical vapor deposition) or CVD (chemical vapor deposition).
JP-A-61-72634 discloses forming a ceramic layer of i3N4 or HfN.

However, it is inevitable that the crystal grains of the metal base material themselves will grow due to the temperature cycles of glass forming and hot working, and the crystal structure will change, causing roughness on the surface of the thin ceramic layer. In severe cases, the ceramic layer may peel off.

Therefore, there is a strong desire to develop a mold material that has desirable glass molding properties and improved structural and thermal properties.

The present invention solves the problems of the prior art described above, and provides an optical fiber that is extremely easy to process and has excellent mold releasability from glass without deteriorating the surface smoothness of the press molded product even during temperature cycles in thermal open molding. We aim to provide molds for press molding parts.

[Means and effects for solving the problems] That is, the present invention resides in a mold for molding a glass product, characterized in that it is made of glass or glass ceramics containing nitrogen and fluorine.

Since the mold related to the present invention contains nitrogen and fluorine, it has excellent mold releasability for the glass product to be molded, and also has excellent shape reproducibility because the coefficient of thermal expansion exhibits linearity. Such molds are made of glass or glass-ceramic materials that contain nitrogen and fluorine, which have poor affinity with oxidizing air, and exhibit a tapering temperature higher than the molding temperature of the glass product to be molded. The shape is mirror polished. The temperature at the point where the thermal expansion curves of slow strain and quenched glass intersect in a region below the glass transition temperature Tg is referred to herein as devarging temperature.

In particular, in order to ensure mold releasability between the press forming surface and the molded glass product that tends to react, it has sufficient strength, is stable even during forming temperature cycles during hot processing, and has a uniform shape without deterioration of specularity. The press molding surface is formed of a material capable of forming a continuous mold release film. Such materials include MgF2, CaF
2, CeF3, etc. (7) 7-/compound, SiO, 5i0
2, CeO3.

An oxide such as An, 03.5n02, etc. having a melting point higher than the molding temperature cycle of the glass product can be used.

In addition, in order to strengthen physical vapor deposition, Cr, ITO
(Indium-tin mixture).

A conductive film such as SnO2 is formed as a first layer on the press molding surface, and TiN and CrN are deposited on top of it.

CrCN, BN, AJIN', SiC, Si'3 N4
It is also possible to completely cover a ceramic film such as T iB2, T I C, Ba C, etc.

Such a release film can be applied to the press molding surface of a press mold for glass products by, for example, vacuum deposition, sputtering, or high frequency ion blasting.

It can be formed by various methods such as dipping and chemical vapor deposition. The thickness of the mold release film produced is 0 even including the conductive thin film.
．． It is desirable that the thickness be about 1 to several microns.

[Example] Hereinafter, the present invention will be specifically explained with reference to Examples.

The press molding die 1 shown in FIG.
In the illustrated example, the molding surface 3 is formed into a spherical shape.

As for the glass material constituting the mold body 2, the glass to be formed is about 4
In the case of SF8 with a glass transition temperature of 70°C, oxynitride φ glass (Y (12,7) -S i
'u8.8) -A or (8,7) -O(57,8)
-N (4,4) ) is used. The molding surface 3 is processed by ordinary glass grinding and polishing, which has high shape accuracy and easy mirror finishing, to form one or two Newt rings and a surface roughness of 0.01-0.
Do this so that it is less than 0.02 μm.

Using the pair of press molds 1.1 thus manufactured, press molding is performed under the following conditions.

First, as shown in FIG.
Place a. This assembly was heated in an electric furnace (
(not shown). The heating temperature is 580° C., which is around the softening point of the glass material 7, and the heating time is about 1 hour. During this time, a weight W is placed on the upper mold and a pressure of 50 g/cm2 is applied to the glass material 7. After molding, when the glass molded body is slowly cooled to approximately 200°C and taken out from the mold, it does not adhere to the molding surface 3 at all, and the high shape accuracy and surface roughness of the molded surface 3 are directly transferred to the surface of the molded body. A pressed lens that does not require polishing can be obtained.

The mold body 2 of the press molding mold l shown in Fig. 1 has a high depurging temperature of 800°C, so as long as the mold is continued to be used below this temperature, the shape of the molding surface will not change at all, and the amorphous Therefore, unlike metals, crystal grains do not grow and the surface roughness of the molding surface 3 does not deteriorate.On the other hand, with conventional stainless steel molds, crystal grains grow when the temperature exceeds about 500°C. Because of this, there are limits to its use as a mold for molding glass products.

In addition, fluorine-containing glass ceramics (Li20-A1203-M) that precipitates mica crystals are used as the glass material for the mold body.
gO-Na20-ZnO-5iO2-ZrO2-TiO
A similar pressed lens can be obtained even if the molding process using 2-F) is performed under the same conditions as described above.

Using a mold 1 whose molding surface 3 is coated with MgF as a mold release film 4 as shown in FIG. Heat and mold. Heating was carried out at 560 °C near the softening point of the glass material for about 1 hour, during which time 20 g / c layer 2
After applying a pressure of
This results in a press lens that does not require any polishing and does not fuse to the molding surface at all, and has high shape accuracy and surface roughness that are directly transferred.

As mentioned above, compared to conventional stainless steel molds, the molding mold of this example not only has sufficient thermal properties for use in high-temperature ranges of 200°C or higher, but also has a mirror-like surface that is superior to metals and ceramics. It has the characteristic that it can be easily polished with high precision without producing pinholes or grain boundaries. Further, since it contains nitrogen and fluorine and is further provided with a mold release film, fusion of the glass to be molded is effectively prevented and mold release becomes easy.

In the above-mentioned examples, the molding temperature was set near the softening point of the glass to be molded, but the molding temperature is not limited to this; as long as it is above the glass transition point of the glass to be molded, the molding pressure can be several tens of g/am2. It can be molded with a 1-gloss finish, and the mold strength is sufficient.

The material for the release film is not limited to nitrides or fluorides, and similar effects can be obtained with films of the various oxides mentioned above.

FIG. 3 shows another example of the present invention, in this case the mold 1
Glass ceramics, which precipitates mica crystals at a temperature higher than the glass depurging temperature, is used as the material for the mold body 2, and the molding surface 3 is processed into an aspherical shape by polishing and grinding with an NC-controlled processing machine, etc. according to the required accuracy. has been done.

This molding surface 3 is first coated with 0.
A Cr conductive Wi5 having a thickness of 1#1■ is formed to impart conductivity to the mold 1, and then a release film 4 of BN having a thickness of 1.5 .mu.m is formed thereon by an ion blasting method.

Since the mold release film 4 is a dense ceramic thin film with poor wettability with glass, fusion of the glass to be molded is prevented for a longer period of time. Since the glass-ceramic material of the mold body is an insulator, it is not possible to directly form a mold release film thereon; therefore, a conductive film is formed on the molding surface in advance, and then a mold release film is formed. In addition to Cr, thin films such as ITO and 5n02 may be used as the conductive film, and as the ceramic for forming the release film,
TiN, CrN, CrCN, BN.

AuN, SiC, Si3N,, TiB2.

It may be appropriately selected from TiC, B4C, etc. depending on the molding temperature, pressure, etc.

[Effects of the Invention] Generally, glass molding involves temperature and pressure. In other words, molding at a temperature near the glass transition point requires tens of kg/cm2.
A pressure of several grams is required, and molding at a temperature near the softening point requires a pressure of several grams.
A mold made of glass, which can be used at a pressure of /c+w2, is used in such a way that it does not crack or change its shape within such temperature and pressure ranges. In this regard, one aspect of the invention is to use nitrogen- and fluorine-containing glasses or glass-ceramics with high depurging temperatures as molds for press-molding glass products. This makes it possible to perform press molding even at temperatures where conventional stainless steel molds cannot be used due to crystal grain growth, and also facilitates high-precision polishing of the molding surface.

In other words, b. In the present invention, the shape of the molding surface is determined by using materials that easily react with the mold and materials that do not.

Accuracy 9 Glass products, such as press lenses, with surface roughness etc. reliably transferred can be obtained without being fused to a mold. Furthermore, the mold of the present invention can be manufactured at a significantly lower cost than conventional molds made of stainless steel or ceramics.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing a first example of the mold according to the invention, FIG. 2 is a sectional view showing a second example of the mold according to the invention, and FIG. 3 is a sectional view showing a third example of the mold according to the invention. FIG. 4 is an explanatory diagram showing the state of forming glass to be formed using the mold according to the present invention. 1... Molding mold 2... Mold body 3... Molding surface 4... Mold release coating 5... Conductive film 6;... Adjustment mold 7... Glass material patent applicant Olympus Optical Kogyo Co., Ltd. N Figure 1 Figure 2

Claims (1)

[Claims] (1) A mold for molding a glass product, characterized in that it is made of glass or glass ceramics containing nitrogen and fluorine.