JPH0710562A - Die for molding optical device - Google Patents

Abstract

PURPOSE:To obtain a die for molding optical device unreactive with a glass at a high temp., durable against high temp. high pressure and rapid change of temp. and excellent in durability by using a material stable at a high temp., having high strength at a high temp. and excellent in workability as the base material of the die and ion implanting a noble metal or copper to the molding face. CONSTITUTION:As the base material of the die, a sintered hard alloy, i.e., a thermet or a ceramic is used. A noble metal (e.g. platinum) or copper is used for the ion. A post-acceleration system ion implantating device or the like having Freeman type ion source and 200kV max. accelerating voltage is used as the ion implantating device. As the example of ion implantation, thickness of the implantating layer is about 10nm in the condition that the ion kind is platinum, the implantating quantity is 1X10<17>ion/cm<2> and the energy is 200keV, and practically the implantating concn. is preferably 10-80atm%. From the experiments, releasing property becomes worse after continuously using the conventional platinum film die 1000 times and releasing defect is generated after continuously using it 1100 times, but this die is free from stripping and excellent in die releasing after continuously using it 2000 times.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mold for molding an optical element used when forming an optical element molded product by press molding.

[0002]

2. Description of the Related Art A pressure molding method is used as a method for relatively easily obtaining an aspherical lens and an optical element having a complicated shape. In order to obtain a glass optical element by this method, it is necessary to heat the glass material and the molding die to a considerably high temperature, and during pressure molding (press molding) with the molding die,
At the boundary between the glass material and the molding surface, the reaction causes defects such as fusion and clouding. In order to prevent this, measures such as providing a reaction-preventing layer on the surface of the molding material have already been taken. But in this way,
It is necessary to attach a reaction prevention layer to all molding materials,
This will increase the cost of the product.

To take full advantage of the glass mold,
It is desired that the glass material can be supplied at a low cost as much as possible without surface treatment of the molding material. Therefore, it is necessary that the reaction preventive layer is provided on the surface of the molding die, and that it has excellent durability and does not cause defects such as deformation over a long period of time.

As one of the means, there are many methods such as forming a thin film of platinum or a noble metal alloy or a mixture thereof with a nitride, a carbide, an oxide or a boride on the molding surface of a molding die. Proposed.

[0005]

However, the glass molding technology in recent years has been
High pressure (glass molding pressure: 150 k) is being used as part of the means for shortening the molding cycle.
Pressing at g / cm ² or more) and repeating temperature rise and fall (about 100 ° C./min or more; maximum temperature 550 ° C. or more) in a short time are carried out in the process of continuous molding.
In order to carry out this, extremely severe conditions are indispensable for the mold. Under these conditions,
When a molding die having a thin film such as platinum or a noble metal alloy on its molding surface is used, its durability is significantly impaired.

[0006]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances. The object of the present invention is not to react with glass even at high temperature, at high temperature and high pressure, and withstand abrupt temperature change. And to provide a molding die for an optical element having excellent durability.

[0007]

Therefore, in the present invention,
As a mold base material for an optical element molding die, a material having high temperature stability, high temperature and high strength, and excellent workability is used, and a noble metal or copper is provided on the optical element molding surface of the base material by an ion implantation method. There is. That is, in the molding die, a layer of noble metal or copper is formed at least on the molding surface by the ion implantation method.

As the die base material, in addition to cemented carbide,
A cermet or a ceramic material having excellent mirror surface properties and durability can be used.

[0009]

EXAMPLES Examples of the present invention will be specifically described below. Example 1 In this experiment, a Freeman type ion source, 90
Degree-deflecting electromagnetic mass spectrometer, electrostatic beam scanner,
A post-acceleration type ion implanter with a maximum acceleration voltage of 200 KV is used. Further, in this apparatus, ion implantation into φ200 mm is possible. Using such a device, on the molding surface of the molding die of the optical element according to the present invention, under the following conditions,
Ion implantation is performed. Ion species: Pt ⁺ Implantation amount: 1 × 10 ¹⁷ ions / cm ² Energy: 200 keV Note that the thickness of the implantation layer under these conditions was about 10 nm, but the thickness of this implantation layer was By changing the value, it is possible to arbitrarily change the value to a value suitable for the glass forming conditions.

The Pt concentration on the outermost surface of the film under these conditions was about 25 atomic%, but from the practical point of view, the Pt concentration is preferably in the range of 20 to 80 atomic%. As a condition required for the glass molding die, when the Pt concentration lower limit value is lower than 10 atomic%, the mold releasability at the time of molding is deteriorated, continuous molding becomes impossible, and the Pt concentration upper limit value becomes lower. This is because if the value is higher than 80 atomic%, many fine scratches are generated during molding, and the appearance of the molded product is significantly impaired, resulting in a defective product.

Next, an example in which a glass lens is press-molded by the optical element molding die according to the present invention will be described. Here, a desired shape, a molding die in which Pt is ion-implanted by the above method on the molding surface of the cemented carbide base material processed into a surface state, and as a comparative example, on the molding surface of the base material,
A molding die was prepared in which TiN was coated as an intermediate layer for 1 μm, and a Pt film was coated thereon for a thickness of 1 μm (see FIG. 1).

Next, a case will be described in which an optical lens is molded using this molding die by the molding apparatus shown in FIG. In the figure, reference numeral 102 is a molding device, and 104.
Is a substitution chamber for intake, 106 is a molding chamber, 11
Reference numeral 0 is a take-out replacement chamber. Further, reference numerals 112 and 114
Is a gate valve, 118 is a rail, and 1
A pallet 20 is conveyed on the rail 118 in the direction of arrow A. Reference numerals 124, 138, 140, 150
Is a cylinder, and 126 and 152 are valves. Reference numeral 128 is a heater arranged in the molding chamber 106 along the rail 118.

In the molding chamber 106, a heating zone 106-1 and a press zone 1 are arranged in this order along the pallet conveying direction.
It is divided into 06-2 and slow cooling zone 106-3. At the lower end of the rod 134 of the cylinder 138 in the press zone 106-2, the upper mold member 13 for molding is formed.
0 is fixed, and the rod 13 of the cylinder 140 is fixed.
A lower mold member 132 for molding is fixed to the upper end of 6.
The upper mold member 130 and the lower mold member 132 are
The mold member according to the configuration of the present invention is as described above.

Here, first, the crown glass BAL
42 (softening point Sp = 672 ° C., glass transition point Tg = 55
(0 ° C.) is roughly processed into a predetermined shape and size to obtain a glass blank for forming. Then, the glass blank is installed on the pallet 120, and the intake and replacement chamber 10 is replaced.
4 in the position 120-1 and pushes the pallet in the above position in the direction A by the rod 122 of the cylinder 124 to move over the gate valve 112 to the position 120-2 in the molding chamber 106. To do. Similarly, at a predetermined timing, the pallets in the intake / substitution chamber 104 are newly introduced into the molding chamber 106 at predetermined timings.
The sheet is sequentially transported from the position -2 to the position →→ 120-8. Meanwhile, in the heating zone 106-1, the glass blank is gradually heated by the heater 128 and is conveyed to the press zone 106-2. Where the cylinder 138
And 140 are operated to apply a pressure of 200 kg / cm ^{2 to} the glass blank at a predetermined temperature for 1 minute using the upper mold member 130 and the lower mold member 132 to perform press molding. Thereafter, the pressure is released, the temperature is cooled to a temperature near the glass transition point, and then the cylinders 138, 14
0 to operate the upper mold member 130 and the lower mold member 132.
Release the glass molding from. In the press molding, the pallet is used as a body member for molding. Thereafter, in the slow cooling zone 106-3, the glass molded product is gradually cooled. The molding chamber 106 is filled with an inert gas. In the molding chamber 106, the pallet that has reached the position of 120-8 passes through the gate valve 116 in the next transfer, and is taken out from the replacement chamber 1.
It is conveyed to the position of 120-10 in 10. And
At the time of the next transportation, the cylinder 150 is operated and the rod 148 takes out the glass molded product to the outside of the molding apparatus 102.

Next, the temperature cycle of the molding die in such a molding process was set as shown in FIG. 3 in the repeated experiment. That is, the temperature is increased from 530 ° C., which is the temperature of charging glass, to 620 ° C., which is the molding temperature, in 1 minute (heating rate 90 ° C. /
Minute), then press-molding for 1 minute, then 6
A glass molded article was subjected to a control condition of decreasing the temperature from 20 ° C. to 550 ° C. of the mold release temperature in 1 minute (temperature decreasing rate 70 ° C./min),
When molding is performed 2000 times continuously, the results are shown in Table 1.

In this experiment, in the conventional Pt film type,
The mold releasability of the molding die deteriorated after about 1000 times continuously, and the peeling failure of the molding surface of the molding die occurred around 1100 times continuously. However, with the Pt ion-implanted mold of the present invention, there was no peeling of the ion-implanted layer in the molding mold even after continuous 2000 tests, and the mold release was also good. Also, a Pt ion-implanted molding surface before and after continuous molding, in which peeling of the ion-implanted layer does not occur,
The surface roughness of the molded product at the 00th shot is Rma
At x = 0.02 μm, deterioration of the molding die was not observed in this experiment. In comparison with this, in the conventional Pt thin film type, the surface roughness of the portion where no peeling of the film occurred was Rmax = 0.1 μm after 2000 times of molding, which was considerably rough. . This is presumed to be due to surface deterioration due to platinum grain growth and fine scratches.

[0017]

[Table 1] Example 2 Next, BAL62 (BAL42 low softening point glass; softening point Sp = 607 ° C., glass transition point Tg =) A case where a molding test is continuously performed 2000 times at 506 ° C.) will be described. The temperature cycle of the mold set in this experiment is as shown in FIG.
Here, the temperature is raised from the glass charging temperature of 490 ° C. to the molding temperature of 570 ° C. in 1 minute, and press molding is performed for 1 minute at the temperature of 570 ° C. under the same pressing force as described above. The pressure is released and the temperature is lowered from 570 ° C. to the mold release temperature of 510 ° C. in 1 minute. Under the above conditions, the result of continuous press molding 2000 times is
It is as shown in Table 2.

In this experiment, in the conventional Pt film type,
After about 1400 times continuously, the mold releasability deteriorated, and after about 1500 times continuous, peeling of the film in the molding die occurred. However, with the Pt ion-implanted mold of the present invention, there was no peeling of the ion-implanted layer of the molding mold even after continuous 2000 tests, and the mold release was good. In addition, the surface roughness of the Pt ion-implanted molding surface before and after continuous molding in which the separation of the ion-implanted layer did not occur, and the surface roughness of the molded product at the 2000th shot were both Rmax = 0.02 μm. No deterioration of the molding die was observed in the experiment. On the other hand, in the case of the conventional Pt thin film type, the surface roughness of the portion where no peeling of the film occurs is Rmax = 2000 after 2000 times.
It became 0.1 μm. This is presumed to be due to surface deterioration due to platinum grain growth and fine scratches, as in Example 1.

[0019]

[Table 2] Next, the compositions of the glasses used in Examples 1 and 2 are shown in Tables 3 and 4.

[0020]

[Table 3]

[0021]

[Table 4] 5 and 6 show the analysis results (by the secondary ion mass spectrometry method) of the change in the surface element concentration before and after forming the glass in Example 1. From this analysis result, it is understood that Li ₂ O and Na ₂ O contained in the glass are released from the surface by the molding. Of these, Li and Na may react with the metal components present on the molding surface of the molding die to cause poor fog of the molded product. However, in this experiment, such a bad fog did not occur. Considering these results, in the Pt thin film type, Example 2 was used.
The reason why the durability in Example 1 (BAL42) was worse than that in (BAL62) is considered to be because the molding temperature conditions were more severe in Example 1. In any case, the mold of the present invention, in which Pt was ion-implanted into the molding surface, did not cause any defects in molding for 2000 consecutive shots, and good molding results were obtained. [Example 3] Next, using the same molding apparatus as in Example 1 and the molding die of the present invention, and as a comparative example, the molding die was used as an intermediate layer on the cemented carbide base material. TiN 1 μm
By using two molds which are coated and Pt is coated thereon with two kinds of film thicknesses of 1 μm and 0.05 μm, lead-free flint-based glass NPH1 (SF6 equivalent, yield point At = 59)
1 ° C., glass transition point Tg = 559 ° C.), 300
A case where the continuous molding test is performed 0 times will be described.

The temperature cycle of the molding die in this experiment is shown in FIG. Here, the glass input temperature is 490 ° C.
To a molding temperature of 630 ° C. in 40 seconds (heating rate of 210 ° C./min), and at the temperature of 630 ° C., a pressing force similar to the above is applied for 1 minute to perform press molding, and thereafter, The pressure control was released, and the temperature control conditions were set such that the temperature was lowered from 630 ° C. to the mold release temperature of 510 ° C. in 40 seconds (cooling rate 180 ° C./min). The mold release temperature was set lower than in the case of Example 1 because the mold release property due to the difference in glass components (NPH1 has more alkaline components than BAL42) was taken into consideration. The composition of the glass NPH1 is shown in Table 5. Table 6 shows the molding results under these conditions.

[0023]

[Table 5]

[0024]

[Table 6] NPH1 contains more alkali elements in the glass component than BAL42 and BAL63. Therefore, it is considered that the possibility that these elements react with the metal component present on the molding surface of the molding die to cause the clouding failure of the molded article is higher than in Examples 1 and 2. However, in this experiment, such a bad fog did not occur.

Considering the durability against peeling of the film, the Pt film thickness of the molding die as a comparative example is as follows.
0.05 μm → 2000 times, 1 μm → 500 times,
A mold having a smaller Pt film thickness tends to have higher durability in terms of film peeling. It is considered that this is because when the film is thick, the internal stress of the film becomes large and the adhesion of the intermediate layer to TiN becomes weak. However, even under such severe temperature conditions, no defects were found in the Pt ion implantation type of the present invention. The surface roughness of the mold after 3000 times of continuous molding and the surface roughness of the molded product at the 3000th shot are Rmax = 0.03 μm.
It was at a level that could be put to practical use. In the Pt film type film remaining portion of the comparative example, Rmax =
It was 0.2 μm. This is for the same reason as in the first and second embodiments.

In these examples, cemented carbide was adopted as the base material of the molding die, but as another base material, the cemented carbide base material was mirror-polished and With TiN deposited on it, with TiN deposited on a cemented carbide base material and mirror-polished, or with CVDSi on a SiC base material.
Needless to say, the same effect as in the case of the above-mentioned embodiment can be obtained even if Pt ions are implanted into a film in which C is formed and mirror-polished. Further, although not specifically mentioned in the above-mentioned examples, a forming test using a forming die in which copper is ion-implanted is also performed after the cemented carbide base material is mirror-finished into a desired shape. According to it, by forming the ion-implanted layer, the lack of hardness, which is a weak point of copper, is solved, and at the same time, the property of copper that it is difficult to react with glass is utilized, and the same molding property as in the above-mentioned embodiment is obtained. I was able to obtain results.

[0027]

The present invention has been made as described above.
By using a molding die that has undergone t-ion implantation, even if molding is performed under severe temperature cycles, there is no peeling of the film as seen in the conventional Pt thin film molding die, and good mold releasability is maintained for a long time. It becomes possible to withstand a sudden temperature change repeatedly, and as a result,
The durability of the glass molding mold has been greatly improved.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a molding die according to the present invention.

FIG. 2 is a configuration diagram of a molding apparatus that molds an optical element using the molding die.

FIG. 3 is a graph showing setting conditions of a temperature cycle of the molding die of Example 1.

FIG. 4 is a graph showing setting conditions of a temperature cycle of the molding die of Example 2.

FIG. 5 is a result of surface element concentration analysis of BAL42 before molding.

FIG. 6 is a result of surface element concentration analysis of BAL42 after molding.

FIG. 7 is a graph showing setting conditions of a temperature cycle of the molding die of Example 3;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Platinum injection layer 2 Type base material 102 Molding apparatus 104 Intake displacement chamber 106 Molding chamber 110 Extraction displacement chamber 112 Gate valve 114 Gate valve 118 Rail 122 Rod 124 Cylinder 126 Valve 128 Heater 130 Upper mold 132 Lower mold 134 Rod 136 Rod 138 Cylinder 140 Cylinder 148 Rod 150 Cylinder 152 Valve

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Yasushi Taniguchi 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Keiji Hirabayashi 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. Within the corporation

Claims (4)

[Claims] 1. A material which is excellent in high temperature stability, high temperature and strength, and is excellent in processability is used as a mold base material of an optical element molding die, and a noble metal or copper is ion-implanted into the optical element molding surface of the base material. A mold for molding an optical element, which is provided by a method. 2. The mold base material is made of cemented carbide, cermet or ceramics.
A mold for molding an optical element according to item 1. 3. Platinum is used as the precious metal of the molding surface,
The optical element molding die according to claim 1, wherein the concentration is 10 to 80 atomic%. 4. The copper concentration on the molding surface is 10 to 80 at.
The optical element molding die member is characterized in that