JP4585558B2 - Optical glass element mold - Google Patents

Description

  The present invention has good releasability with glass even in repeated molding of a glass material such as phosphate glass having a high reactivity and a high softening temperature, and is excellent in durability, and further, discoloration of the protective film during molding, The present invention relates to an optical glass element mold capable of effectively suppressing deterioration.

For compact cameras such as digital cameras and other optical systems, it is desired to use a high refractive index material for miniaturization. In addition, lenses used in the field of optical communication are required to use optical materials with high refractive index and high durability for their miniaturization and use environment.
Conventionally, optical glass containing a large amount of lead has been used as a high refractive index material, but the appearance of an optical material containing no lead has been desired due to environmental problems.
Against this background, phosphate glasses including K-PSFn1 (trade name, manufactured by Sumita Optical Glass Co., Ltd., nd: 1.068) have been developed. Since K-PSFn1 contains phosphoric acid as a main component and has a high softening temperature, when it is molded by a direct press method, the reaction with the mold (mold) is very strong.

In recent years, in the manufacture of optical glass elements, a direct press molding method that does not require polishing or the like after press molding of glass has been frequently used due to the necessity of mass productivity. In order to obtain a precise optical glass element by direct press molding, the glass press surface of the mold is inactive with the high-temperature glass and the adhesion between the mold and the glass is low. A mold with high conductivity is required.
As such a mold, one in which a molding surface of a base material (base material) is coated with an alloy thin film mainly composed of platinum (Pt) or iridium (Ir) has been proposed (see Patent Documents 1 and 2). ). However, in this mold, when phosphate glass is repeatedly molded, phosphorus in the glass diffuses into the protective film of the mold during molding, and the mold releasability between the mold and the glass is impaired. This phenomenon is remarkable in the formation of phosphate glass having a high softening temperature such as K-PSFn1.
As a method for increasing the adhesion strength between the protective film constituting the optical glass element molding surface and the element molding die base material, a metal or an alloy is provided between the protective film constituting the molding surface and the optical glass element molding die base material. There is a method of providing an intermediate layer formed by a thin film made of at least one of silicon carbide, silicon nitride, and silicon oxide (see Patent Document 3). However, the method of providing an intermediate layer of silicon carbide, silicon nitride, and silicon oxide is complicated to manufacture and is economically disadvantageous.

Further, the applicant of the present application is based on the above knowledge, and is capable of forming an optical glass element having good mold releasability between the glass and the mold and good adhesion between the mold base and the protective film on the glass molding surface of the mold base. As a mold, an optical glass element mold having a single-layer protective film having molybdenum (Mo) as a first component and iridium (Ir) as a second component has been proposed (see Patent Document 4).
However, in an optical glass element molding die provided with a protective film having the composition disclosed in Patent Document 4 on the glass molding surface, volatiles from glass, carbide (WC) diffused from the base material into the protective film, or a binder ( Co, Ni, etc.) may cause adhesion of the glass to be molded to the molding surface and discoloration of the protective film. In particular, further improvement of the protective film provided on the glass molding surface of the optical glass element molding die is desired. It was rare.

Japanese Patent Publication No.63-11285 Japanese Patent Publication No. 4-16415 Japanese Patent Laid-Open No. 10-231129 JP 2005-41739 A

  An object of the present invention is an optical glass element molding die in which a protective film layer is provided on a glass molding surface through an intermediate layer, which solves the above-mentioned problems, and the color change is caused not only by the deterioration of the protective film due to volatile substances. Can be effectively suppressed, and in the repetitive molding of a glass having a high reactivity and a high softening temperature such as phosphate glass, the releasability from the glass to be molded is good and various optical properties can be obtained. An object of the present invention is to provide an optical glass element mold having high adhesion strength between a glass element mold base and a protective film and excellent durability.

The optical glass element molding die of the present invention is a base material having high heat resistance and oxidation resistance, and an intermediate layer formed on the glass molding surface of the base material, and includes Zr, Ti, V, Cr, Mo, Nb At least one selected from the group consisting of Pd and Au, or an intermediate layer made of these alloys, and a group formed on the intermediate layer made of Ru, Rh, Pd, Re and Au At least the one of 10 to 40 weight percent, Ir, at least the one of 20 to 80 wt% selected from the group consisting of Pt, a protective film made of the M o or Mo + W from 1 to 60 wt% of the alloy, from It is characterized by.

Moreover, as a suitable example of the optical glass element shaping | molding die of this invention, the thickness of an intermediate | middle layer is 0.05-2 micrometers, and the film thickness of a protective film is 0.05-10 micrometers.

As a result of intensive studies on the composition of the protective film at the time of molding the optical glass element having a protective film provided on the glass molding surface, the present inventor has provided an intermediate layer, and the intermediate layer is further composed of Zr, Ti, V, Cr, 10 to 40% by weight of at least one selected from the group consisting of Mo, Nb, Pb, and Au, or an alloy thereof, and at least one selected from the group consisting of Ru, Rh, Pd, Re, and Au. When a protective film made of an alloy containing 20 to 80% by weight of at least one selected from the group consisting of Ir, Pt and 1 to 60% by weight of Mo or Mo + W is used, for example, glass made of phosphate glass phosphate glass even when the conducted molded element not only difficult to adhere to the molding surface, deterioration of the protective film due to volatilization of such H _{2 O} generated during molding of the glass element, Fine discoloration obtain a finding that can be effectively suppressed.

According to the optical glass element molding die of the present invention, even if a glass element made of phosphate glass having a high softening temperature is repeatedly molded, the protective film hardly reacts with phosphorus in the raw glass, and forms an intermediate layer. Therefore, since the diffusion of carbide (WC) or binder (Co, Ni, etc.) from the base material is suppressed, the protective film is not deteriorated and the releasability from the glass is not impaired. For this reason, adhesion of glass to the mold does not occur, and a highly accurate optical glass element can be molded.
In addition, the intermediate layer in the present invention has a high adhesion strength to optical glass element molding die base materials (molding die base materials) such as cemented carbide, aluminum oxide, cermet, and silicon carbide. The material and the protective film are brought into close contact with each other.
Further, the surface of the protective film forms a passive state to suppress the oxidation of the protective film, and the protective film is deteriorated, discolored, and volatile by volatile substances such as H ₂ O generated from the glass during molding of the optical glass element. In addition to extending the life of the mold, the mechanical strength of the optical glass element molding can be further increased by adding Re, Ru, and / or Rh, etc. to the protective film. Can do.

Hereinafter, the glass mold of the present invention will be described with reference to the drawings.
FIG. 1 schematically shows an example of a glass mold according to the present invention, and is a cross-sectional view comprising a pair of upper and lower molds. In FIG. 1, 2 and 3 are optical glass element mold base materials, 4 is an intermediate layer, and 5 is a protective film.

The optical glass element mold bases 2 and 3 are heat-resistant, dense and highly heat-conductive materials. Specific examples of suitable materials include cermet (TiC-Ni alloy), silicon nitride ( Si ₃ N ₄ ), cemented carbide (WC-Co, W-Ni, etc.), aluminum oxide, cermet, silicon carbide and the like. Although the cemented carbide has the characteristics that it is softer and has higher workability than silicon carbide, it has a drawback that it is easy to proceed with oxidation gradually because of the presence of a binder and is somewhat vulnerable to oxidation. Silicon carbide (SiC) has a feature that it has a very high hardness and poor workability, but is resistant to oxidation and has a long life. Aluminum oxide and cermet are in the middle. Considering these characteristics, the types of the optical glass element mold bases 2 and 3 are appropriately selected depending on the number of lots to be produced and the type of glass.

  The intermediate layer 4 laminated on the glass molding surface of the optical glass element molding die of the present invention (that is, the surface of the glass molding substrate 2, 3) is Zr, Ti, V, Cr, Mo, Nb, Pd and Au. It consists of at least 1 type chosen from the group which consists of these, or these alloys.

The protective film 5 is at least one selected from the group consisting of Ru, Rh, Pd, Re and Au, at least one selected from the group consisting of Ir and Pt, and at least selected from the group consisting of Mo or Mo + W Made of a kind of alloy.

The content of at least one selected from the group consisting of Mo or Mo + W is 1 to 60% by weight, preferably 2 to 40% by weight. Even if any content is less than 1% by weight or more than 60% by weight, the effect of suppressing film deterioration and discoloration by volatiles such as H ₂ O generated by glass heating at the time of molding can be obtained. I can't get it.

The content of at least one selected from the group consisting of Ir and Pt is 20 to 80% by weight, preferably 30 to 50% by weight. If the content of any of them is less than 20% by weight or more than 80% by weight, the hardness of the protective film 5 is lowered, and the surface of the protective film 5 is easily damaged. Furthermore, the effect of suppressing film deterioration and discoloration due to volatile substances such as H ₂ O generated by heating the glass during molding cannot be obtained.

The content of at least one selected from the group consisting of Ru, Rh, Pd, Re and Au is 10 to 40% by weight, preferably 15 to 35% by weight. Even if the content of any of them is less than 10% by weight or more than 40% by weight, the effect of suppressing film deterioration and discoloration due to volatiles such as H ₂ O generated by glass heating during molding can be obtained. Absent.

Au is not an essential component of the protective film 5 provided on the molding surface of the optical glass element molding die of the present invention, but may be contained up to 20% by weight. By including Au in the protective film 5, an effect of suppressing film deterioration or discoloration due to reaction with glass or reaction with volatiles such as H ₂ O generated by glass heating can be obtained. If it is contained in an amount of more than 20% by weight, the hardness of the protective film 5 is lowered, and the surface of the protective film 5 is likely to be damaged, which is not preferable. The more preferable Au content is 0 to 10% by weight.

  In particular, a material such as cemented carbide, aluminum oxide, cermet, or silicon carbide is used as the mold bases 2 and 3, and the intermediate layer 4 having the above composition is laminated on the molding surface of the mold bases 2 and 3. For example, the adhesion strength with the mold bases 2 and 3 is high, and further, diffusion of carbide (WC) or binder (Co, Ni, etc.) from the base material is suppressed. For this reason, since the protective film 5 which comprises a shaping | molding surface does not cause deterioration, the shaping | molding die excellent in durability can be obtained.

The method for forming the intermediate layer 4 and the protective film 5 is not particularly limited, and various methods can be adopted. For example, at least one selected from the group consisting of Ru, Rh, Pd, Re, and Au, Ir, Pt A method in which a target is prepared by sintering each metal powder of at least one selected from the group consisting of and at least one selected from the group consisting of Mo or Mo + W , and consists of a single component metal. Other component chips may be placed on the target and sputtering, ion plating, or the like may be employed. The composition of the intermediate layer 4 and the protective film 5 is adjusted by, for example, the blending ratio of each metal powder used as a raw material when preparing the target in the case of sputtering, and in the case of on-chip, the number of chips is a desired number. It can be adjusted by changing to

  The thickness of the intermediate layer 4 is preferably 0.05 to 2 μm, and more preferably 0.1 to 1 μm. If the thickness of the intermediate layer 4 is less than 0.05 μm, the object of the present invention for providing the intermediate layer 4 is not achieved, and even if the thickness is greater than 2 μm, the technical effect is saturated.

  The thickness of the protective film 5 is preferably 0.05 to 10 μm, and more preferably 0.1 to 1 μm. If the thickness of the protective film 5 is less than 0.05 μm, the object of the present invention for providing the protective film 5 is not achieved, and even if the thickness is larger than 10 μm, the technical effect is saturated.

  The optical glass element molding die of the present invention is optimally applied particularly to the molding of optical glass elements made of phosphate glass. In addition to phosphate glass, borosilicate glass K-PBK40 is used. {Product name, Sumita Optical Glass Co., Ltd., refractive index (nd): 1.5176, Abbe number (νd): 63.5, transition point (Tg): 501 ° C., yield point (At): 549 ° C.}, Ho Lanthanum acid glass K-VC79 {trade name, manufactured by Sumita Optical Glass Co., Ltd., refractive index (nd): 1.61035, Abbe number (νd): 57.9, transition point (Tg): 516 ° C., yield point (At ): 553 ° C.), zinc borate glass K-ZnSF8 (trade name, manufactured by Sumita Optical Glass Co., Ltd., refractive index (nd): 1.7143, Abbe number (νd): 38.9, transition point (Tg): 518 ° C., yield point (At): 546 ° C.}, etc. It can be suitably used for molding of the scan.

  Next, an example explains the present invention. Note that the present invention is not limited to the materials, compositions, and manufacturing methods described in the following examples.

<Examples 1 to 6 >
A glass mold base made of a cemented carbide (WC 99 wt%, remaining Co and inevitable components) having a diameter of 12 mm is formed on the concave surfaces having a curvature radius of 10 mm (glass mold base 3) and 20 mm (glass mold base 2), respectively. The processed surface was polished with a diamond paste having a particle size of 0.5 μm, and the molding surface was a mirror surface. Thus, a pair of upper and lower glass mold bases 2 and 3 were produced.
On the other hand, targets for forming a protective film were prepared by sintering or dissolution processing with the coating compositions of Examples 1 to 6 shown in Table 1 below, and further sintered or dissolved with the composition of the intermediate layer in Table 1 below. A processed metal target for forming an intermediate layer was prepared. Next, the pair of upper and lower optical glass element forming mold bases 2 and 3 produced as described above are set in a sputtering apparatus, and each of the glass forming mold bases 2 and 3 is used using a metal target for forming an intermediate layer. An intermediate layer 4 having a thickness of 0.5 μm is formed on the molding surface, and a protective film 5 shown in FIG. 1 is formed to a thickness of 2 μm on the surface of the intermediate layer 4 using a protective film-forming target sintered with the above composition. By doing this, the optical glass element shaping | molding die of Examples 1-6 was manufactured.

Using the optical glass element molds of Examples 1 to 6 manufactured as described above, phosphate-based high melting point glass K-PSKFn1 {trade name, manufactured by Sumita Optical Co., Ltd., refractive index (nd): 1.068, Abbe The molding machine shown in FIG. 2 is made from a preform obtained by processing a number (νd): 21.2, a transition point (Tg): 498 ° C., and a yield point (At): 543 ° C.} into a ball preform having a diameter of 7 mm. The optical glass lens was molded in the following manner.
In FIG. 2, reference numeral 10 denotes a chamber, in which a heater 11 is set in a cylindrical shape, and a lower shaft 12 is provided inside the cylindrical heater 11 and an air cylinder provided outside the top of the chamber 10. The upper glass 13 connected to the upper shaft 13 is set, and the optical glass element forming mold bases 2 and 3 each having the protective film 5 laminated on the molding surfaces of the upper and lower shafts 13 and 12 are fixed, respectively. And the lower mold.

The ball preform is placed between the upper mold and the lower mold of the molding machine, and nitrogen is injected into the chamber 10 at a rate of 10 L / min. And press-molded. After the press, the product was cooled to a temperature of 250 ° C., and the lens as a molded product was taken out.
When this is performed 3000 times, glass adheres to the protective film 5 surfaces of the upper optical glass element mold base material 2 of Examples 1 to 6 and the lower optical glass element mold base material 3. And deterioration and discoloration were not confirmed visually.
In the evaluation, “deterioration” means that the protective film 5 does not have the performance required for the original protective film 5 such as releasability and heat resistance, or the protective film 5 is discolored and is inherently in the protective film 5. This refers to the case where the required performance is still maintained but the color is changed.
The results are shown in Table 1 below.

<Comparative Examples 1-2>
Targets sintered respectively with the composition ratios of Comparative Examples 1 and 2 shown in Table 1 were prepared, and a pair of upper and lower optical glass element forming mold bases 2 and 3 prepared as in Examples 1 to 6 were used as a sputtering apparatus. A comparative example is obtained by setting the protective film 5 shown in FIG. 1 to a thickness of 2 μm without providing the intermediate layer 4 using the target having the above composition on each molding surface of the glass mold bases 2 and 3. 1-2 optical glass element molds were produced.

When press molding was performed in the same manner as in Examples 1 to 6 , glass adhesion to the molding surface of the molding die, glass adhesion to the molding surface protective film, and deterioration of the protective film were observed up to 1500 times.
The results are shown in Table 1 below.

  The optical glass element mold of the present invention can effectively suppress discoloration as well as deterioration of the protective film due to volatiles, and it is a repetitive glass having high reactivity and high softening temperature like phosphate glass. Also in molding, since the releasability from the glass to be molded is good, and the adhesion strength between the various optical glass element molding substrate and the protective film is high and excellent in durability, glass with a high softening temperature, particularly And can be suitably used for molding phosphate glass or the like.

It is sectional drawing which shows typically an example of the optical glass element shaping | molding die of this invention. It is sectional drawing which shows typically an example of the press molding apparatus of the optical element used in the Example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Optical glass element shaping | molding die 2, 3 Optical glass element shaping | molding die base material 4 Intermediate | middle layer 5 Protective film 10 Chamber 11 Heater 12 Lower shaft 13 Upper shaft 14 Air cylinder

Claims (1)

A base material having high heat resistance and oxidation resistance and an intermediate layer formed on the glass molding surface of the base material, selected from the group consisting of Zr, Ti, V, Cr, Mo, Nb, Pd and Au. 10 to 40% by weight of at least one selected from the group consisting of at least one kind or an alloy thereof, and Ru, Rh, Pd, Re and Au formed on the intermediate layer. An optical glass element comprising: 20 to 80% by weight of at least one selected from the group consisting of Ir, Pt, and a protective film made of an alloy of Mo or Mo + W of 1 to 60% by weight. Type.

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