JP2001270730A - Releasing layer for press-molding oxynitride glass, method for forming the releasing layer, mold for press- molding, and press-molded product - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a releasing layer most suitable for exhibiting excellent releasing properties even when used at such a high temperature that an oxynitride glass is subjected to press-molding, to provide a method for most suitably forming the releasing layer, to provide a press-mold for most suitably molding the molded product, and to provide a press-molded product of the oxynitride glass having an excellent surface smoothness. SOLUTION: This releasing layer for press-molding the oxynitride glass comprises a vapor deposited film of amorphous carbon and/or amorphous carbon nitride. A press-molded product which is press-molded by using the releasing layer has such a surface roughness that the maximum height (Rmax) is not more than 500 nm, and a center line mean roughness (Ra) is not more than 50 nm, when measured by a method specified in JIS B0601.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a release layer and a method of forming a release layer for obtaining a pressed oxynitride glass body having a smooth surface which can be used for disks for recording media such as magnetic disks. The press mold having excellent surface smoothness on which the release layer should be formed, and the oxynitride glass having excellent surface smoothness press-molded using the mold having the release layer formed thereon. It relates to a press-formed body.

[0002]

2. Description of the Related Art In the field of magnetic disk drives, technical developments are being made more and more rapidly in order to improve recording density and transfer speed. In recent years, there has been an urgent need to increase the speed of the disk, particularly with the aim of improving the transfer speed, and a disk material having a high specific rigidity (= Young's modulus / density) that does not vibrate even during high speed rotation has been demanded. . The specific rigidity of an aluminum disk (hereinafter, referred to as an aluminum disk) conventionally used is 26.7 (= Young's modulus: 72 GPa / density: 2.7 g / cm ³ ), and the disk is rotating at a high speed of 10,000 rpm. It is said that a specific stiffness of twice or more is required for use. However, in order to double the specific rigidity of the aluminum disk, there is only a method of compounding with a ceramic (MMC) or the like, and the practical possibility is low in terms of cost.

On the other hand, a glass disk used in a 2.5-inch size (hereinafter, referred to as a glass disk) is
Attention is drawn to the fact that high specific rigidity is easily achieved. For example, many attempts have been made to improve the Young's modulus by heat-treating the glass at an appropriate temperature to precipitate a crystal phase having a high Young's modulus, thereby forming a glass-ceramic. For example, JP-A-6-329440 and JP-A-8-111024
JP-A-8-221747 discloses an example in which a lithium dioxide crystal and an α-quartz crystal are precipitated. Japanese Patent Application Laid-Open No. 9-77531 discloses that spinel crystals are precipitated to lower the Young's modulus of 109-1.
An example in which the specific rigidity is improved to 44 GPa and 36 to 47 is disclosed. However, although the specific rigidity of the glass itself increases due to crystallization, the composite structure of the hard crystal phase and the soft glass phase results in fine steps during polishing, and the super mirror surface required for the disk is obtained. There is a disadvantage that is difficult to be.

On the other hand, as a measure for improving the specific rigidity of the glass itself, a measure for adding a rare earth element, which is expected to increase the Young's modulus of the glass, is also known. However, the addition of a rare earth element increases the Young's modulus of the glass and at the same time increases the density, and as a result, the specific rigidity does not improve as expected.

Therefore, as a method of increasing the Young's modulus without significantly increasing the density of the glass, use of an oxynitride glass in which oxygen in the glass is replaced with nitrogen has been studied. The present applicant has studied the composition of an oxynitride glass that can provide a high Young's modulus, and has already filed an application for the result of the study (Japanese Patent Application No. 11-110).
96987).

[0006] The applicant of the present application has conducted various studies with the aim of establishing an industrial production method of oxynitride glass. In order to apply oxynitride glass to a disk for a recording medium such as a magnetic disk, for example, to obtain a thin disk-shaped disk, the press molding method is most effective when mass-produced industrially. Therefore, a release layer, press conditions, and a press mold suitable for press molding were examined, and the results of each investigation were already filed (Japanese Patent Application No. 11-36833).
7, Japanese Patent Application No. 11-368338, Japanese Patent Application 2000-3
No. 9999).

[0007] The applicant of the present application has been conducting further studies in order to obtain a press-formed body of oxynitride glass having even better surface smoothness. Since oxynitride glass has a higher viscosity than other glasses, a high temperature of 1000 ° C. or more is required for press molding. Under such high temperature conditions, oxynitride glass is melted into a press molding die. A release layer is required for easy attachment. At this time, the surface smoothness of the press-formed body obtained by the press-forming method is greatly affected by the surface shape of the forming die and the release layer. For this reason, when press molding is performed using a release layer or a molding die having a rough surface, the surface of the obtained press molded body becomes rough, and severe surface smoothness (for example, J
The maximum height R _max is 10n defined by IS B0601
m or less, and the center line average roughness _Ra is 1 nm or less).

Therefore, in order to obtain a desired final shape, in particular, surface smoothness, a polishing step such as rough polishing of the surface of the molded body and further finish polishing is performed. But,
If the surface of the press-formed body before polishing is extremely rough, the amount of polishing must be increased, the glass to be polished and removed is wasted, and the polishing time increases, so that the polishing cost increases. There has been a problem that the price of products such as disks has risen.

[0009]

Accordingly, in the present invention, the amount of glass removed in the polishing step after press molding is reduced, and the polishing cost is reduced by shortening the polishing time, thereby reducing the cost of the final product. To achieve
It is an object of the present invention to obtain a press-formed body of oxynitride glass having excellent surface smoothness. Then, an optimal release layer exhibiting excellent releasability even under high temperature conditions when press-molding oxynitride glass, an optimal method of forming the release layer, and forming the release layer. The object of the present invention was to find an optimal press-molding die and to provide a press-formed body of oxynitride glass having excellent surface smoothness.

[0010]

The first invention of the present application relates to a release layer for press-molding oxynitride glass, which is used for obtaining a pressed-molded oxynitride glass having excellent surface smoothness. The layer has a gist where it is made of a deposited film of amorphous carbon and / or amorphous carbon nitride. The deposited film of amorphous carbon and / or amorphous carbon nitride exhibits excellent releasability even under high-temperature conditions when press-molding oxynitride glass. In addition, since the deposited film strongly adheres to the molding surface of the molding die and forms a release layer having a uniform thickness, it prevents fusion of the oxynitride glass to the molding die and has excellent surface smoothness. A press molded article of oxynitride glass can be obtained. The thickness of the release layer is preferably 1 to 1000 nm.

The second invention of the present application relates to a method for forming a release layer for press-molding oxynitride glass. In forming this release layer on a molding surface of a press-molding die, a physical vapor deposition method is used. Have a gist. The vapor-deposited film obtained by the physical vapor deposition method adheres strongly to the molding surface of the molding die having a smooth surface, and becomes dense and uniform in thickness. It is possible to obtain a press-formed body having excellent smoothness.

In particular, the use of a sputtering method is preferable, and the condition is that the molding surface temperature of the press mold is set to 0.
~ 400 ° C, sputtering gas pressure 0.1 ~ 3P
a, It is preferable to set the sputtering power density to 1 to 10 W / cm ² in order to form a deposited film of amorphous carbon and / or amorphous carbon nitride.

[0013] The third invention of the present application is a press-molding die suitable for oxynitride glass on which a release layer is formed, and JIS B0601 of a molding surface of the press-molding die.
The point is that the maximum height Rmax defined by the _formula is 1000 nm or less and the center line average roughness _Ra is 100 nm or less. By using a press mold having a smooth surface as described above, a press molded body having excellent surface smoothness can be obtained.

According to a fourth aspect of the present invention, there is provided a mold containing a release layer in which the release layer according to the first aspect is formed on the molding surface of the mold according to the third aspect by the method according to the second aspect. Press-formed body of oxynitride glass obtained, wherein the maximum height R of the surface of the press-formed body specified by JIS B0601
_The gist lies in that the _max is 500 nm or less and the center line average roughness _Ra is 50 nm or less. By press-molding using a molding die provided with the optimal release layer on the molding surface of the optimal press molding die by the optimal forming method, such a press molding with excellent surface smoothness A body can be obtained, and as a result, the amount of glass removed in the polishing step can be reduced, and the polishing cost can be reduced by shortening the polishing time, so that the cost of the final product can be reduced.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the present invention, when press-molding oxynitride glass, a deposited film of amorphous carbon and / or amorphous carbon nitride is provided on a molding surface of a molding die as a release layer. The greatest feature is that a press-formed body having excellent surface smoothness can be obtained by using the above. Hereinafter, the present invention will be described in detail.

The release layer of the present invention must be a deposited film of amorphous carbon and / or amorphous carbon nitride. As the form of the release layer, any of an amorphous carbon single layer, an amorphous carbon nitride single layer, a mixed layer of both, or a layer in which a plurality of these layers are laminated can be adopted. The temperature at which the oxynitride glass can be spread by pressing depends on the composition of the glass, but is usually 1000 to 1800 ° C., and the deposited film of amorphous carbon and / or amorphous carbon nitride has heat resistance to this temperature. It exhibits excellent release properties without fusing the oxynitride glass to the molding die. In the case of a deposited film of diamond or graphite, irregularities due to the shape of diamond particles or graphite particles are inevitably formed on the surface of the deposited film, and the surface smoothness of the obtained press-formed body is deteriorated. It is not preferred in the invention.

Further, a part of the release layer composed of the deposited film of the amorphous carbon and / or amorphous carbon nitride adheres to the surface of the press-formed body after the formation, but the air is heated at a high temperature (300 ° C. or more). If it is oxidized in the atmosphere or even at low temperature by oxygen plasma ashing, oxides of C and N are generated and volatilized from the glass surface as carbon dioxide and nitrogen dioxide, so that the pressed body is polished without damaging it. This also has the advantage that these release layers can be removed without doing so.

The thickness of the release layer made of a deposited film of amorphous carbon and / or amorphous carbon nitride is 1 to 10
It is preferably set to 00 nm. Release layer thickness of 1 nm
If it is less than 3, the release layer is easily broken at the time of press molding, and the oxynitride glass and the molding die may be fused at the broken portion. On the other hand, if the thickness of the release layer exceeds 1000 nm, the releasability is saturated, so that it is useless to increase the thickness further. Further, even if a press-molding die having a smooth surface is used, the surface smoothness of the molding surface is difficult to be transferred to a glass press-molded product, and it is difficult to obtain a press-molded product having a smooth surface, which is not preferable.

The release layer composed of a deposited film of amorphous carbon and / or amorphous carbon nitride is formed by a thin film forming method such as physical vapor deposition (PVD) and chemical vapor deposition (CVD). It can be formed. However, in CVD, a vapor deposition film may not be formed depending on the material of a molding die, and even when a vapor deposition film can be formed, the thin film formation speed is lower than that of PVD or the like. In contrast, PVD
In the case of using a mold made of a material having heat resistance to the press molding temperature of oxynitride glass, a deposited film can be formed irrespective of the material, and the thin film forming speed is high. Therefore, it is preferable that the release layer composed of the deposited film of amorphous carbon and / or amorphous carbon nitride of the present invention is formed by PVD.

The PVD includes a vacuum deposition method, an ion plating method, a sputtering method and the like, and among these, the sputtering method is particularly preferable. Since the deposited film obtained by the sputtering method has excellent uniformity in thickness on the surface on which a thin film is to be formed (molding surface of the molding die), the surface smoothness of the press molding die faithfully matches the surface of the press molded body. Will be transcribed. In the sputtering method,
Since a vapor-deposited film having strong adhesion to a very smooth molding surface can be formed, excellent releasability can be obtained, which can be said to be the most preferable method for forming a release layer.

In order to form a release layer of the present invention, that is, a deposited film of amorphous carbon and / or amorphous carbon nitride by a sputtering method, it is preferable to select appropriate sputtering conditions. The condition is
The temperature (substrate temperature) of the molding surface of the press mold is 0 to 40.
0 ° C., a sputtering gas pressure of 0.1 to 3 Pa, and a sputtering power density of 1 to 10 W / cm ² . The sputtering power density is defined as the power (W) applied to the cathode (here, the sputtering target) is the area (c) of the surface of the sputtering target facing the substrate.
m ² ). In the sputtering conditions, conditions other than the above specific conditions may be known conditions, but if the substrate temperature, the sputtering gas pressure, and the sputtering power density are not set in the above ranges, the obtained deposited film may have a crystalline property such as diamond or graphite. As described above, unevenness due to diamond particles or graphite particles is formed on the surface of the vapor-deposited film, which deteriorates the surface smoothness of the obtained press-formed body, which is not preferable.

As a sputtering gas, it is preferable to use an argon gas when forming an amorphous carbon deposited film, and to use a mixed gas of argon gas and nitrogen gas when forming an amorphous carbon nitride deposited film. Good. As the sputtering device, a direct-current sputtering device, a high-frequency sputtering device, a magnetron sputtering device, or the like can be appropriately selected. In addition,
A release layer may be provided on the glass gob before pressing by a sputtering method.

The release layer of the present invention described so far is
Since it is strongly adhered to the molding die, even if the smoothness of the surface of the press molding die is increased, the disadvantage that the adhesion to the molding die is reduced and the releasability is deteriorated does not occur. In addition, since it is an extremely thin release layer showing excellent release properties, the smoothness of the surface of the molding die is increased, and this smoothness is transferred to oxynitride glass, whereby the obtained press-formed body is obtained. The surface smoothness can be made very excellent. As a result, the polishing cost can be reduced, and the cost of the product obtained from the oxynitride glass can be reduced.

[0024] Thus, in the present invention, as the mold, its maximum height R _max which is defined in JIS B0601 of the molding surface is 1000nm or less, the center line average roughness R _a is 1
It is recommended to use one with a thickness of 00 nm or less. On a molding surface, a portion having a maximum height R _max of more than 1000 nm, or a center for press molding in which a portion having _a center line average roughness Ra of more than 100 nm is present, the surface of the obtained press-formed body is preferably roughened. Absent. The molding surface of the press molding die means a circular surface of the die when a thin disk-shaped molded body is formed. The maximum height R _max and the center line average roughness R _a of the molding surface can be measured using a stylus type or non-contact, two-dimensional or three-dimensional surface roughness measuring instrument. Surface roughness measuring instruments provided with a calculation function, a calibration function, and the like are commercially available from Kosaka Laboratory Co., Ltd., Meishin Koki Co., Ltd., and the like.

As a material for the mold for press molding, graphite or glassy carbon having heat resistance to the press molding temperature of oxynitride glass is preferable.
Patent application 2000-3999 filed by the present applicant
No. 9 is described. Further, in order to set the surface smoothness of the press mold within the above range, an appropriate polishing means may be selected.

By using a press mold having excellent surface smoothness as described above, a press molded body having a smooth surface can be obtained. As a standard of the surface smoothness of the molded body, the maximum height R _max is 500 nm or less, and the center line average roughness _Ra is 50 nm or less. Maximum height R _max is 500nm
Or the center line average roughness _Ra is 50 nm
In the press-formed body having a portion exceeding the above, the amount of polishing must be increased in order to finish a disk requiring high surface smoothness, and glass is wasted. In addition, since the polishing time is long, the polishing cost is increased, which is repelled to the product cost. However, if the maximum height R _max is 500 nm or less and the center line average roughness _Ra is 50 nm or less, there is no need to perform rough polishing, and both the polishing amount and the polishing time can be reduced.
Cost reduction of products such as recording medium disks such as magnetic disks can be achieved.

The press-formed body of the present invention is finished and polished by a polishing step to obtain a final product. Although the finish polishing method is not particularly limited, for example, after cleaning the molded body obtained by press molding, the molded body is placed in a holder of a polishing apparatus, and the polished surface of the molded body is brought into contact with a polyurethane polisher, and the pressure is 5000 Pa, Polishing can be performed at a speed of 2 m / sec. 0.5μ particle size for abrasive
Polishing may be performed while using a diamond powder having a diameter of m and dropping this abrasive together with a lubricant at a flow rate of 5 g / min onto the surface of the polisher.

Although the composition of the oxynitride glass that can be used in the present invention is not particularly limited, M ¹ —Al—Si—ON (M ¹ is Ca, Mg, Y,
An oxynitride glass represented by one or more of Gd, Ce and La); M ² —Si—ON (M ² is Ca and / or M
Any of the oxynitride glass represented by g) and the oxynitride glass obtained by mixing two or more of these glasses are preferable.

In general, M ¹ is Ca, Mg,
A composition that is one of Y, Gd, Ce and La is known, but two or more metal elements may be mixed. Also, both Mg and Ca may be mixed. Is a case where two or more types of glass are mixed before pressing. The most preferred composition of the oxynitride glass used in the present invention is a metal component composition which exhibits a high Young's modulus and becomes a homogeneous glass.
No. 96987.

The oxynitride glass is obtained by reducing a metal oxide (SiO ₂ , Al ₂ O ₃ , MgO, CaO, etc.) and a nitride serving as a nitrogen source (Si ₃ N ₄ , AlN, BN, etc.) in a reducing atmosphere. It can be manufactured by a method of mixing under a low temperature and quenching after melting at a high temperature. A method of melting a metal oxide in N ₂ gas or NH ₃ gas, a method of blowing N ₂ gas or NH ₃ gas into molten glass by bubbling, a method of firing porous glass in NH ₃ gas, and the like are also adopted. It is possible.

The press forming conditions (temperature, load, time) of the oxynitride glass are not particularly limited, but it is preferable to select the press forming conditions suitable for the composition of the oxynitride glass. This is described in detail in Japanese Patent Application No. 11-368338.

[0032]

The present invention will be described in more detail with reference to the following examples. However, the following examples do not limit the present invention, and all changes and modifications within the scope of the present invention are included in the present invention. It is.

Experimental Example 1 A molding die for producing a disk-shaped press molded body having a diameter of 96 mm and a thickness of 1.2 mm was made of glassy carbon. Using a stylus type surface roughness meter (“Talysurf 6” manufactured by Taylor Hobson), JIS of the molding surface of the molding die
When the surface roughness defined by B0601 was measured, the maximum height R _max was 500 nm, and the center line average roughness _Ra was 50 n.
m.

The molding surface of the molding die has a thickness of 1000 n.
A release layer composed of an amorphous carbon film having a thickness of m was formed by a sputtering method. Sputtering was performed under the following conditions.

Sputtering equipment: "SPUT" manufactured by Shimadzu Corporation
TERING SYSTEM HSM-752 "Sputtering target: Carbon disk with a diameter of 15.24 cm and thickness of 0.5 cm Sputtering method: DC magnetron sputtering Substrate (molding mold) temperature: 20 ° C Sputtering gas: Argon Sputtering gas pressure: 0.4 Pa Sputtering Power density (= sputtering power /
Sputtering target area): 5.5 W / cm ²

Similarly, two more molding dies having the same surface roughness as the above-mentioned molding dies were prepared, and one of them was formed by sputtering an amorphous carbon nitride film having a thickness of 1000 nm on the molding surface. One is that the molding surface has a thickness of 10
A diamond film of 00 nm was formed by sputtering. The amorphous carbon nitride film was formed by using a sputtering gas of a mixed gas of argon and nitrogen as the above sputtering conditions. The diamond film has a substrate temperature of 50 under the above sputtering conditions.
It was formed at 0 ° C. Note that the amorphous carbon film, the amorphous carbon nitride film, and the diamond film
Each was identified by Raman spectroscopy. Then, the surface roughness of the release layer was measured by the stylus type surface roughness meter.

Next, Ca-Al-S was placed in each mold.
i-ON-based oxynitride glass (Ca: 20 equivalent%, Al: 20 equivalent%, Si: 60 equivalent%, O: 80
(Equivalent%, N: 20 equivalent%) disk-shaped glass gob (mass 25.2 ± 0.2 g, diameter 35.7 ± 2.2 mm, thickness 8.9 ± 0.5 mm), and press temperature 1125
Press molding of a reheat press method was performed under the conditions of ° C, a press load of 43200 N, and a press time of 140 seconds. When the mold was opened after press molding, the press molded body did not adhere to the molding die, and the mold was released cleanly. The sample that was impossible to release was evaluated as x, and the release property was evaluated.

For the obtained press-formed body, the maximum height R _max and the center line average roughness _Ra were measured using the above-mentioned stylus type surface roughness meter. The maximum height R _max is in 500nm or less is a preferred surface smoothness of the measure in the present invention, the surface smoothness when the press-molded article was obtained in which the center line average roughness R _a is satisfied 50nm or less ○, obtained If not, the surface smoothness of the press-formed body was evaluated as x. Table 1 summarizes the measurement results of the surface roughness, and the evaluation results of the releasability and the surface smoothness.

[0039]

[Table 1]

As is clear from Table 1, in the present invention example in which the amorphous carbon film (Sample No. 1) and the amorphous carbon nitride film (Sample No. 2) were used as the release layer, the release layer had a smooth surface. It was confirmed that the surface of the press-formed body obtained was also excellent. On the other hand, in the comparative example in which the diamond film was used as the release layer, the releasability was exhibited, but the surface of the release layer was rough. It was found that the range was not satisfied.

Experimental Example 2 In the same manner as in Experimental Example 1, a molding die (having a maximum height _Rmax of 5
(The center line average roughness _Ra was 50 nm). A thickness of 0.5, 1, 100, 100 was applied to the molding surface of the molding die in the same manner as in Experimental Example 1.
An amorphous carbon film or an amorphous carbon nitride film having a thickness of 5000 nm was formed by a sputtering method. Using these molds, oxynitride glass was press-molded in the same manner as in Experimental Example 1, and the releasability and the surface smoothness of the press-formed body were evaluated based on the same criteria as in Experimental Example 1. Table 2 shows the evaluation results.

[0042]

[Table 2]

As is clear from Table 2, the amorphous carbon film of the present invention having a thickness of 1 to 1000 nm (Sample No. 5)
7) and an amorphous carbon nitride film (sample No. 10
No. 12) was excellent as a release layer because it was excellent in mold release properties and also excellent in surface smoothness of the obtained press-formed body. On the other hand, in the reference examples having too small thicknesses (Sample Nos. 4 and 9), the releasability tended to be slightly inferior. Also, the reference example (sample No. 8,
In 13), the surface smoothness of the press-formed body tended to be slightly inferior.

Experimental Example 3 A press-molding die for producing a disk-shaped press-formed body having a diameter of 96 mm and a thickness of 1.2 mm was made of glassy carbon. At this time, the polishing conditions were changed to change the surface roughness of the molding surface of the press molding die as shown in Table 3. For the molding surface of the molding die, as in Experimental Example 1,
An amorphous carbon film having a thickness of 1000 nm was formed by a sputtering method. Using these molding dies, press molding of oxynitride glass was performed in the same manner as in Experimental Example 1, the surface roughness of the obtained press molded body was measured, and the surface smoothness was measured in the same manner as in Experimental Example 1. Evaluation was based on criteria.

Next, the obtained press-formed body was polished. After washing the press-formed body, it is placed in a holder of a polishing apparatus, and the polished surface of the formed body is brought into contact with a polyurethane polisher, and the polishing agent (particle size: 0.5 μm Was ground together with a lubricant at a flow rate of 5 g / min. At this time, measure the polishing time,
The pressed body is made to have a desired surface smoothness (maximum height R _max is 1).
0 nm or less, and the center line average roughness _Ra is 1 nm or less).
If the finishing can be performed within seconds, the polishing cost can be reduced. If the polishing time exceeds 30 seconds, the polishing cost cannot be reduced, and the result is evaluated as x. Table 3 shows the evaluation results.

[0046]

[Table 3]

As is clear from Table 3, the press-formed bodies (sample Nos. 14 to 16) of the present invention obtained by the press-forming mold having a smooth surface had a maximum height _Rmax of 500 nm or less and a center line. The average roughness _Ra is 50 nm or less;
It turns out that it is excellent in surface smoothness. In addition, it was confirmed that polishing cost can be reduced in the press-formed body having excellent surface smoothness.

[0048]

According to the present invention, an optimum release layer exhibiting excellent release properties even under high temperature conditions when press-molding oxynitride glass, and an optimum method of forming this release layer are found. Was completed. Further, since the release layer of the present invention adheres strongly to the molding die, even if the smoothness of the surface of the press molding die is increased, the adhesiveness with the molding die is reduced to deteriorate the mold release property. Not cause any inconvenience,
By increasing the smoothness of the surface of the molding die and transferring this smoothness to oxynitride glass, the surface smoothness of the obtained press-formed body can be made extremely excellent. . Furthermore, as a result, the amount of glass that must be removed in the polishing step after press molding can be reduced, and the polishing time can be shortened. Has enabled the cost reduction of products obtained from oxynitride glass. The press-formed body of oxynitride glass obtained by the present invention is particularly suitable for a high specific rigidity disk for a recording medium such as a magnetic disk.

Claims (6)

[Claims] 1. A release layer used to obtain a press-formed body of oxynitride glass having excellent surface smoothness, comprising a deposited film of amorphous carbon and / or amorphous carbon nitride. Release layer for press molding of oxynitride glass. 2. The method according to claim 1, wherein the thickness is 1 to 1000 nm.
3. A release layer for press-molding the oxynitride glass according to 1.). 3. The release layer for press molding of oxynitride glass, wherein the release layer according to claim 1 or 2 is formed on a molding surface of the press molding die by a physical vapor deposition method. Forming method. 4. A sputtering method is used as a physical vapor deposition method. As for sputtering conditions, the temperature of the molding surface of the press molding die is 0 to 400 ° C., the sputtering gas pressure is 0.1 to 3 Pa, and the sputtering power density is 1 to 4. 10
4. The method for forming a release layer for press-molding oxynitride glass according to claim 3, wherein the release layer is W / cm ² . 5. A press-molding die which is suitable for oxynitride glass in which the release layer is formed, the maximum height R _max which is defined in JIS B0601 of the molding surface of the press mold is 1000nm Hereinafter, the center line average roughness _Ra
Having a particle size of 100 nm or less. 6. The release layer according to claim 1 or 2, wherein the release layer is formed on the molding surface of the press mold according to claim 5 by the forming method according to claim 3. A press-formed body of oxynitride glass obtained by a molding die containing JIS B060.
A press-formed body of oxynitride glass, wherein the maximum height _Rmax specified in 1 is 500 nm or less and the center line average roughness _Ra is 50 nm or less.