JPS6365613B2 - - Google Patents

Description

[Detailed description of the invention]

(Industrial Application Field) The present invention relates to a method for manufacturing an optical glass lens,
More specifically, the present invention relates to a method for manufacturing a press molding die used for manufacturing an optical glass lens by direct press molding, which requires only press molding and does not require a subsequent polishing step. (Conventional Structure and its Problems) Optical glass lenses are increasingly becoming aspherical, which can simultaneously simplify the lens structure of optical equipment and reduce the weight of the lens portion. In the production of aspherical lenses, there has been a problem in that the conventional optical lens production method using the optical polishing method has extremely low workability and mass productivity. Direct press molding is seen as a promising solution to this problem. The direct press molding method uses an aspherical mold whose molding surface has been finished to the desired quality and precision in advance, and heats it on the mold, or it simply molds a pre-heated block of optical glass. This manufacturing method does not require post-processes such as polishing and lapping after press molding. Therefore, in the direct press molding method, the optical glass lens as press-molded must have excellent quality and precision so that the image forming quality of the lens is not impaired. requires high precision. In order to meet this requirement, the mold material must have minimal chemical effects on glass at high temperatures, and must be resistant to damage such as scratches on the molding surface.
It is necessary to have high fracture resistance against thermal shock. To achieve this purpose, molds made of silicon carbide (SiC), silicon nitride (Si ₃ N ₄ ), or molds with a film of silicon carbide or the like formed on high-density carbon are considered suitable. , various studies are being conducted. However, silicon carbide, silicon nitride, etc. have extremely high hardness, so it is extremely difficult to process them with high precision as molds for molding spherical or aspherical lenses. Since the lenses are molded by sintering, substances that react relatively easily with glass, such as alumina (Al ₂ O ₃ ) and boron oxide (B ₂ O ₃ ), are used as sintering aids, which makes it possible to form lenses with high precision. There was a problem that it could be molded. On the other hand, in molds made of high-density carbon with a silicon carbide coating, the coating is made of beta silicon carbide (β-silicon carbide).
SiC), there is a problem in that sodium (Na) reacts with glass containing a large amount of barium (Ba). Molds using silicon (α-SiC) and types with alpha silicon carbide coatings formed on tungsten carbide (WC) are also being developed, but these also contain large amounts of lead (Pb) and germanium (Ge). There is a problem that it reacts with glass, making it difficult to mold precise aspherical lenses with both. A mold material that has less reaction with glass that contains large amounts of lead (Pb) and sodium (Na), and which can be molded into glass in air, is a mold material that forms a platinum alloy coating on tungsten carbide (WC). There are molds made of zirconia (ZrO ₂ ) coated with a platinum alloy (Japanese Patent Application No. 59-29618); The former has a problem in that the platinum alloy coating peels off due to the difference in thermal expansion coefficient between zirconia and platinum alloy and weak adhesive force. (Object of the Invention) The present invention solves the above-mentioned drawbacks, and is capable of easily performing high-precision processing required for direct press molding molds for optical glass lenses. It is an object of the present invention to provide a method for manufacturing a glass press molding mold that does not react with glass and does not cause peeling of a platinum alloy coating during molding. (Structure of the Invention) In order to achieve the above object, in the present invention, zirconia (ZrO ₂ ) is used as a base material and processed into the shape of a required press molding die, and on the press molding surface,
A platinum alloy film consisting of at least one element selected from iridium (Ir), osmium (Os), palladium (Pd), rhodium (Rh) and ruthenium (Ru) and platinum (Pt) with a thickness of 300 Å or more
Form a film of 2000 Å and add argon (Ar) to this.
Alternatively, nitrogen (N ₂ ) ions are implanted at 10 ¹³ ions/cm ² to 10 ¹⁷ ions/cm ² at an accelerating voltage of 50 kV to 200 kV to form a diffusion layer between the zirconia (ZrO ₂ ) base material and the platinum alloy coating. After forming, iridium (Ir), osmium (Os), palladium (Pd),
At least one element selected from rhodium (Rh) and ruthenium (Ru) and platinum (Pt)
A mold for direct press molding is made by stacking layers of platinum alloy with a thickness of 1 μm to 10 μm. Argon ions (Ar ⁺ ) from above the platinum alloy coating
Alternatively, in the case of implanting nitrogen ions (N ₂ ⁺ ), platinum atoms collided with the implanted argon ions or nitrogen ions obtain the kinetic energy of the implanted ions and repeatedly collide with other platinum atoms one after another.
A so-called cascade collision occurs, and the metal penetrates into the base material zirconia, and the base material zirconia and the platinum alloy coating function to form a diffusion layer. Formation of this diffusion layer provides strong adhesion between the base material and the platinum coating. Needless to say, when a platinum alloy coating is layered on a platinum alloy coating by sputtering, the adhesion between the two coatings is strong because the platinum alloys are mutually bonded to each other, and will not peel off during press forming. The strong adhesive strength between the mold base material and the platinum alloy coating can withstand the repeated thermal cycles of heating the mold required during press molding of glass, press molding of lenses, and subsequent cooling. The press-molding mold provided with
The objective is to obtain a mold for glass press molding in which no chemical reaction occurs between the mold and the glass, and no peeling of the platinum alloy coating occurs. Although ion implantation was performed on a film formed by sputtering on the press molding surface of a mold, it has been found through experiments that the same effect can be obtained even if ion implantation is performed while performing vacuum evaporation. (Description of Examples) Examples of the present invention will be described with reference to FIGS. 1 and 2. FIG. 1 is a perspective view of an upper mold 1 and a lower mold 2 of a glass press molding mold according to the present invention. Both upper and lower molds 1 and 2 are made of cylindrical zirconia (ZrO ₂ ) material with a diameter of 30 mm and a length of 50 mm.
There are multiple shape notches 3, and the lower die 2 has a radius of curvature.
A concave molding surface 5 of 200 mm is formed respectively. These molded surfaces 4 and 5 are wrapped with ultrafine diamond powder to give mirror surfaces with a maximum surface roughness (Rmax) of 0.02 μm in about 2 hours. Next, a platinum alloy having a composition of 95% by weight of platinum (Pt) and 5% by weight of rhodium (Rh) was used on the surfaces of molding surfaces 4 and 5, which had become mirror-finished, to form a film with a thickness of 300 Å by sputtering. After forming a film and implanting nitrogen ions (N ₂ ⁺ ) into this film at an acceleration voltage of 50 kV at an implantation rate of 10 ¹³ ions/cm ² , the film was further deposited to a thickness of 1 μm.
m of platinum iridium (with the same composition)
-Ir) alloy film is formed by sputtering method. An upper mold 1 and a lower mold 2 for glass press molding were obtained by such a manufacturing method. FIG. 2 is a partially cutaway view showing heaters 6 and 7 wound around the outer diameter surfaces of the above-mentioned glass press molding molds 1 and 2, respectively, and attached to upper and lower plungers 8 and 9 of the press. In the same figure, lead oxide (PbO) is 73% by weight and silicon oxide (SiO ₂ ) is 27% by weight.
A lump 10 of lead oxide-based optical glass having a radius of 20 mm and having a composition of 10% by weight is held by a raw material supply jig 11 and heated in a tunnel-shaped preheating furnace 12, and then the glass is heated to a temperature of 700°C. Press pressure 40Kg/between press molding molds 1 and 2
Press molded in ^cm2 . The molded lens, which has been cooled to a temperature of 400° C. together with the upper and lower molds, is taken out from the take-out port 13 after the upper plunger 8 is returned. Through this process, iridium (Ir),
A binary or ternary platinum alloy with platinum (Pt) containing one or two elements selected from osmium (Os), palladium (Pd), rhodium (Rh) and ruthenium (Ru), and argon as the implanted ion. After performing press molding 100 times using a glass press mold manufactured under various conditions using ions (Ar ⁺ ) or nitrogen ions (N ₂ ⁺ ), molding surfaces 4 and 5 of the mold were The table shows the results of observing the surface condition of the molded glass lens. Sample number in table

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[Table] 1 shows the above test results, and there was no peeling on the molding surfaces 4 and 5, and the surface of the molded lens was also good. As a comparative example, we used a conventionally used silicon carbide (SiC) mold, tungsten carbide (WC) or silicon carbide (SiC) as the base material, and formed a platinum alloy film on the molding surface by sputtering, without ion implantation treatment. sample numbers 87 to 89 using molds that are not included in the claims of the present application, and sample numbers 4 to 7, 11 to 14, 18 to 21, 25, with an asterisk (*) attached to sample numbers that are not included in the claims of the present application, 26, 30, 31, 35, 36,
40, 41, 45, 46, 50, 51, 55, 56, 60, 61, 65,
66, 70, 71, 75, 76, 80, 81, 85 and 86 were listed. As can be seen from these comparative examples, if the thickness of the first coating layer is less than 300 Å, the platinum alloy film is too thin, and the diffusion layer formed by ion implantation becomes thin, resulting in a reduction in the thickness of the zirconia (ZrO ₂ ) and platinum alloy. This is because the adhesion between the zirconia (ZrO 2 ) and the platinum alloy becomes insufficient.If the thickness exceeds 2000Å, the platinum alloy film becomes too thick, making it difficult for the invading ions to reach the boundary between the zirconia (ZrO ₂ ) and the platinum alloy, resulting in insufficient adhesion. , the condition worsens. If the accelerating voltage of argon ions (Ar ⁺ ) or nitrogen ions (N ₂ ⁺ ) is less than 50kV, the voltage is too low and the ions do not penetrate sufficiently into the zirconia side, and if it is more than 200kV, the ions will damage the platinum alloy film. Therefore, the condition worsens. If the ion implantation amount is less than 10 ¹³ ions/cm ² , the ion amount is too small and sufficient adhesion between zirconia (ZrC ₂ ) and platinum alloy film cannot ^be obtained;
If it exceeds ^cm2 , the platinum alloy film will be damaged and the surface of the mold will become rough, making it impossible to obtain a high-quality glass molding surface. In addition, if the platinum alloy composition contains less than 60% by weight of platinum (Pt), the strength or hardness of the platinum alloy film will be low, resulting in minute scratches on the molding surface or plastic deformation, causing the molding surface to deteriorate. The surface precision decreases, and if the content exceeds 95% by weight, the press-formed glass becomes colored, but this is because the platinum alloy film becomes easily oxidized at high temperatures. Based on the test results, the invention is limited as described in the claims. Therefore, if a glass press molding mold is manufactured within this limited range, it is possible to obtain a glass press molding mold in which both the molding surface of the mold and the molded glass lens are in good condition. (Effects of the Invention) As explained above, according to the present invention, strong adhesion can be imparted to the platinum alloy film formed on the molding surface using a zirconia (ZrO ₂ ) base material, and lead-based Alternatively, it is possible to obtain a glass press molding mold that has little reactivity with germanium-based glass and is capable of high-precision glass molding.

[Brief explanation of drawings]

FIG. 1 is a perspective view of a glass press molding mold of the present invention, and FIG. 2 is a partially cutaway view of the plunger portion of the press to which the molding mold of FIG. 1 is attached. 1... Upper mold, 2... Lower mold, 3... Notch, 4,
5... Molding surface, 6, 7... Heater, 8, 9... Plunger, 10... Optical glass lump, 11... Raw material supply jig, 12... Preheating furnace, 13... Takeout port.

Claims (1)

[Claims] 1 Zirconia (ZrO ₂ ) is used as a base material and processed into the shape of the required press molding die, and on the press molding surface, iridium (Ir), osmium (Os), palladium (Pd), rhodium (Rh), and ruthenium are added. A platinum alloy consisting of at least one element selected from (Ru) and platinum (Pt), with platinum (Pt) being 60 to 95 weight percent, and the balance being iridium (Ir) and osmium (Os). ,
A film with a thickness of 300 Å to 2000 Å is formed of a platinum alloy having a composition of at least one element selected from palladium (Pd), rhodium (Rh), and ruthenium (Ru), and then argon (Ar) is applied to the film.
Or, after implanting nitrogen (N ₂ ) ions at an acceleration voltage of 50 kV to 200 kV at 10 ¹³ ions/cm ² to 10 ¹⁷ ions/cm ² , Iridium (Ir), Osmium (Os), Palladium (Pd), Rhodium ( Glass press forming characterized by forming layers of a platinum alloy film with a thickness of 1 μm to 10 μm, which is made of platinum (Pt) and at least one element selected from Rh) and ruthenium (Ru). Method of manufacturing molds.