JPWO2008078528A1 - Holding jig, method for manufacturing glass substrate for recording medium using the holding jig, glass substrate for recording medium, and recording medium - Google Patents

Abstract

There are provided a holding jig that does not cause cracks, scratches and cracks in a glass substrate, a method for producing a glass substrate for a recording medium using the holding jig, a glass substrate for a recording medium, and a recording medium. This is a method for manufacturing a glass substrate for a recording medium using a holding jig having flat portions in which the cross-sectional shapes of the side support members that support the glass substrate are parallel to each other.

Description

  The present invention relates to a holding jig, a method for manufacturing a glass substrate for a recording medium using the holding jig, a glass substrate for a recording medium, and a recording medium.

  Conventionally, as a recording medium substrate, aluminum alloys are used for stationary information devices such as desktop computers and servers, and glass substrates are generally used for portable information devices such as notebook computers and mobile computers. It had been. Since the aluminum alloy is easily deformed and has insufficient hardness, the smoothness of the substrate surface after polishing cannot be said to be sufficient. Further, when the recording head mechanically contacts the magnetic disk, there is a problem that the magnetic film is easily peeled off from the substrate. Therefore, glass substrates with little deformation, good smoothness, and high mechanical strength will be widely used not only for portable devices but also for home-use devices such as stationary information devices and other televisions in the future. It is predicted.

  In order to improve the mechanical strength of the glass substrate for recording media, chemical strengthening treatment has been widely performed. In this chemical strengthening treatment, a glass substrate is immersed in a chemical strengthening solution stored in a chemical strengthening treatment tank, and alkali metal ions on the surface of the glass substrate are mixed with alkali metal ions having an ion diameter larger than the alkali metal ions. By replacing, compressive strain is generated, and mechanical strength is improved.

  As a holding jig for holding a glass substrate for a recording medium when performing this chemical strengthening treatment, one described in Patent Document 1 is known. In this holding jig, three shaft-like bodies having a plurality of abacus ball-like projections are fixed to a plate-like side plate in which three holes are formed. Between the protrusions formed on these shaft-shaped bodies, V-shaped valley bottoms are formed, and these valley bottoms can support the outer periphery of the glass substrate. And these shaft-shaped bodies can hold | maintain a some glass substrate so that the side surface of a glass substrate may be orthogonal to the axial direction of a shaft-shaped body by supporting three places of the outer peripheral part of a glass substrate.

When chemically strengthening a glass substrate using such a holding jig, for example, the following method is used. A holding jig holding a plurality of glass substrates is heated in advance to 300 ° C. and immersed in a chemical strengthening treatment bath containing a chemical strengthening treatment liquid at 400 ° C. for about 3 hours. Thereafter, the glass substrate surface can be chemically strengthened by taking out the holding jig holding the glass substrate from the chemical strengthening treatment liquid, immersing it in a 20 ° C. water bath, rapidly cooling it, and maintaining it for about 10 minutes.
JP 2001-195728 A

  However, in the shape of the holding jig in Patent Document 1, the supporting portions that support the two side portions of the glass substrate are V-shaped. When chemically strengthened in this state and taken out from the chemical strengthening treatment solution, the glass substrate may be sandwiched between the two side portions due to contraction of the holding jig, and there is a problem that cracks, scratches, and cracks occur.

  Therefore, the technical problem to be solved by the present invention is a holding jig that does not cause cracks or scratches on the glass substrate, a method of manufacturing a glass substrate for recording medium using the holding jig, a glass substrate for recording medium, and It is to provide a recording medium.

  In order to solve the above problems, the present invention has the following features.

1.
In the holding jig for holding the glass substrate used in the process of chemical strengthening by immersing the glass substrate in the chemical strengthening liquid,
The holding jig includes a plurality of support members and a pair of fixing members to which the support members are attached, and the plurality of support members include a plurality of grooves for supporting the glass substrate. A lower support member that supports the lower part of the substrate, and a side support member that supports the side part of the glass substrate,
A holding jig having flat portions in which the cross-sectional shapes of the grooves of the side support members are parallel to each other.

2.
2. The holding jig according to 1, wherein an entrance of a groove of the side support member is chamfered.

3.
3. The holding jig according to 1 or 2, wherein a distance between flat portions parallel to each other in the groove of the side support member is 1 to 2 mm.

4).
Any one of 1 to 3, wherein a region where any one of the flat portions parallel to each other of the groove of the side support member and the side portion of the glass substrate overlap is 0.5 to 5 mm. The holding jig according to the item.

5).
An inner distance L indicating the side of the glass substrate between the two side support members arranged opposite to each other and an outer diameter G of the glass substrate are 0.2 mm ≦ LG ≦ 5. The holding jig according to any one of 1 to 4, wherein the holding jig has a relationship of 0 mm.

6).
6. The holding jig according to any one of 1 to 5, wherein a cross-sectional shape of the groove of the side support member is a U-shape.

7).
When the cross-sectional shape of the groove of the lower support member is V-shaped, the outer peripheral end of the glass substrate is chamfered at two locations, and the angle formed by the two processed surfaces after chamfering is θ2. The holding jig according to any one of 1 to 6, wherein the V-shaped angle θ1 is within the range of the following formula.

θ2 <θ1 <170 °
8).
The cross-sectional shape of the groove of the lower support member is V-shaped, the outer peripheral end of the glass substrate is rounded, and the V-shaped angle θ1 is 90 ° to 170 °. The holding jig according to any one of 1 to 6.

9.
A cross-sectional shape of the groove of the lower support member is an arc shape, two outer peripheral end portions of the glass substrate are chamfered, and an outer end of the chamfered portion of the glass substrate is chamfered. The holding jig according to any one of 1 to 6, wherein the holding jig is in contact with a cross section.

10.
The cross-sectional shape of the groove of the lower support member is an arc shape with a radius of curvature R1, the outer peripheral end of the glass substrate is rounded, and when the radius of curvature of the outer peripheral end is R2, R1 is R2. The holding jig according to any one of 1 to 6, wherein the holding jig is larger.

11.
In the manufacturing method of the glass substrate for recording media which has the process of chemically strengthening a glass substrate,
1. A method for producing a glass substrate for a recording medium, which is produced using the holding jig according to any one of 1 to 10.

12
A glass substrate for a recording medium, which is produced using the method for producing a glass substrate for a recording medium according to 11.

13.
13. A recording medium comprising a magnetic film on the surface of the glass substrate for recording medium according to item 12.

  According to the present invention, since the cross-sectional shape of the groove of the side support member of the holding jig has a flat portion parallel to each other, the distance between the side support members shrinks with the temperature change in the chemical strengthening process. Even so, the glass substrate is not cracked, scratched or cracked.

It is a flowchart which shows the example of the manufacturing process of the glass substrate for recording media. It is a flowchart which shows the content of the chemical strengthening process process in FIG. (A) is the upper surface of an example holding jig which accommodates and hold | maintains a glass substrate, (b) is sectional drawing of an example holding jig which accommodates and hold | maintains a glass substrate. It is a schematic diagram which shows the state which supported the groove shape of the conventional side part support member, and the glass substrate. It is a schematic diagram which shows the state which supported the groove shape and glass substrate of the side part supporting member which concerns on this invention. It is a schematic diagram which shows the state which supported the glass substrate by which the cross-sectional shape of the groove | channel of the lower support member which concerns on this invention was V-shaped, and two places of the outer peripheral edge part were chamfered. It is a schematic diagram which shows the state which the groove | channel of a lower supporting member and the glass substrate are contacting in the boundary part of the chamfering part and recording surface of a glass substrate. It is a schematic diagram which shows the state which a glass substrate becomes easy to slip | deviate sideways when the V-shaped angle of a lower support member is 170 degrees or more. It is a schematic diagram which shows the state which supported the glass substrate by which the cross-sectional shape of the groove | channel of the lower support member which concerns on this invention was V shape, and the outer peripheral edge part was round-processed. It is a schematic diagram which shows the state which supported the glass substrate by which the cross-sectional shape of the groove | channel of the lower support member which concerns on this invention was circular arc shape, and two places of outer peripheral edge parts were chamfered. It is a schematic diagram which shows the state which supported the glass substrate by which the cross-sectional shape of the groove | channel of the lower supporting member which concerns on this invention was circular arc shape, and the outer peripheral edge part was round-processed. It is a perspective view containing the partial cross section of a magnetic disc.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Glass substrate for recording media 2 Magnetic film DI Magnetic disk 30 Holding jig 31 Glass substrate 32a Side support member 32b Lower support member 34a, 34b Groove 36 Fixing member

  Although the present invention will be described based on the illustrated embodiment, the present invention is not limited to the embodiment.

(Manufacturing process)
The manufacturing method of the glass substrate for recording media is demonstrated. FIG. 1 is a flowchart showing an example of a manufacturing process of a recording medium glass substrate. First, a glass material is melted (glass melting process), molten glass is poured into a lower mold, and press molding is performed with an upper mold to obtain a disk-shaped glass substrate precursor (press molding process). Note that the disk-shaped glass substrate precursor may be produced by cutting a sheet glass formed by, for example, a downdraw method or a float method with a grinding stone, without using press molding.
In the press-molded glass substrate precursor, if necessary, a hole is formed in the central portion with a core drill or the like (coring step).
Next, both surfaces of the glass substrate are polished, and the overall shape of the glass substrate, that is, the parallelism, flatness, and thickness of the glass substrate are preliminarily adjusted (first lapping step).
Next, both surfaces of the glass substrate are polished again to finely adjust the parallelism, flatness and thickness of the glass substrate (second lapping step).
Next, the outer peripheral end surface and the inner peripheral end surface of the glass substrate are ground, and the outer peripheral end portion and the inner peripheral end portion are chamfered, so that the outer diameter and roundness of the glass substrate, the inner diameter of the hole, and the glass substrate and the hole And the concentricity are finely adjusted (inner / outer diameter machining process). Thereafter, the inner peripheral end face of the glass substrate is polished to remove fine scratches (inner peripheral end face processing step), and then the outer peripheral end face of the glass substrate is polished to remove fine scratches (outer peripheral end face). Processing step).

  Next, after the glass substrate is washed, the glass substrate is immersed in a chemical strengthening solution described later to form a chemical strengthening layer on the glass substrate (chemical strengthening step). Thereafter, polishing is performed to precisely finish the surface of the glass substrate (polishing process). Then, cleaning and inspection are performed, and a glass substrate for recording medium as a product is completed. In addition, although there exists a polishing process which polishes after a chemical strengthening process which forms a chemical strengthening layer, the intensity | strength of the glass substrate before and behind this polishing process hardly changes.

  The contents of the chemical strengthening step are shown in the flowchart of FIG. The cleaned glass substrate is preheated (preheating step) and then immersed in a chemical strengthening solution (chemical strengthening solution soaking step). The glass substrate taken out from the chemical strengthening solution is washed with water (water immersion process) and dried (drying process).

  In the chemical strengthening process, when each process from the series of preheating process to drying process is actually performed, for example, the following process is performed. First, prepare a holding jig that holds multiple glass substrates, put the glass substrates together with the holding jig, sequentially into the preheating furnace, soak in the chemical strengthening liquid bath, soak in the cleaning bath, and put into the drying oven By doing so, a series of processes of chemical strengthening can be performed.

  An example of a holding jig for holding a plurality of glass substrates is shown in FIG.

  FIG. 3A is a view of the holding jig 30 as viewed from the side where the glass substrate 31 is accommodated. FIG. 3B shows a state where the glass substrate 31 is held by the support member 32 provided with the grooves 34. The holding jig 30 shown in FIG. 3 has a pair of three side support members 32a and one lower support member 32b each having a plurality of grooves 34 formed at equal intervals in the arrangement direction of the glass substrates 31. The members 36 are connected to each other. In the holding jig 30, the plurality of glass substrates are held by supporting the three portions by the grooves 34 a and 34 b in the same plane of the three support members 32 a and 32 b. Arrange multiple sheets in the existing direction.

  Further, the number of the support members 32a and 32b is not limited to three, but it is preferable that the number of the support members 32a and 32b be three because there are few portions in contact with the glass substrate 31 and they can be stably held.

  The temperature applied to the glass substrate 31 and the holding jig 30 that holds the glass substrate 31 in each step varies depending on the glass substrate material, the chemical strengthening solution, and the like, but is approximately the following, for example. 200 ° C. to 600 ° C. in the preheating furnace in the preheating process, 280 ° C. to 660 ° C. in the chemical strengthening liquid tank in the chemical strengthening liquid immersion process, 35 ° C. to 100 ° C. in the cleaning tank in the water immersion process, and the drying furnace The temperature is from 100 ° C to 150 ° C. Moreover, between each process, it is necessary to move the holding jig 30 in the air at room temperature between the furnaces or tanks. Therefore, the glass substrate 31 and the holding jig 30 are exposed to a large temperature difference such as room temperature and about 600 ° C. from the above example.

  The holding jig 30 exposed to a large temperature difference as described above undergoes thermal contraction when the temperature becomes lower than when the temperature is high. By contracting the fixing member 36 as well, the distance between the two shafts of the side support member 32a is reduced. At this time, in the conventional example shown in FIG. 4, the groove 34a of the side support member 32a is a V-shaped groove, and the end surface of the groove 34a, the edge portion of the outer peripheral end of the glass substrate, and the contact point A are accompanied by thermal contraction. In some cases, the glass substrate 31 does not move smoothly, stress is applied to the glass substrate 31, and cracking or chipping occurs.

  Therefore, in order to solve such a problem, the shape of the groove 34a of the side support member 32a of the holding jig 30 is as shown in FIGS. 5 (a) and 5 (b). Fig.5 (a) is the figure which looked at the side part supporting member 32a of the state which supported the glass substrate from upper direction, FIG.5 (b) is a cross-sectional shape of the side part supporting member 32a.

  As shown in FIG. 5B, the cross-sectional shape of the groove 34a of the side support member 32a is a shape having flat portions parallel to each other, and the entrance of the groove into which the glass substrate 31 is inserted is chamfered. By adopting such a shape, even when the fixing member 36 is thermally contracted and the distance between the axes of the two support members 32a is reduced (arrow S in FIG. 5A), the edge of the outer peripheral end portion of the glass substrate 31 is obtained. The portion is not caught on the side surface of the groove 34a. Therefore, no stress is applied to the glass substrate 31, and the occurrence of cracks, scratches, cracks, and the like can be suppressed. The same effect can be obtained even if the outer peripheral end of the glass substrate 31 is chamfered flat or rounded with a curvature.

  The distance D between the flat portions of the cross-sectional shape of the groove 34a of the side support member 32a is preferably 1 to 2 mm. If the thickness is less than 1 mm, it becomes difficult to insert the glass substrate, and the outer peripheral end portion of the glass substrate 31 is easily scratched. On the other hand, when the thickness exceeds 2 mm, the rattling of the glass substrate 31 increases, and the adjacent glass substrates come into contact with each other, and scratches are likely to occur.

  Moreover, the area | region (d of FIG. 5 (a)) with which either one of the parallel flat parts of the groove | channel 34a of the side part supporting member 32a and the side part of a glass substrate overlap is 0.5-5 mm. Is preferred.

When the number of the lower support members 34b is one, the glass substrate 31 may be biased to one of the side support members 32a. At this time, the overlapping region d in FIG. 5A is the length d0 of the flat portion of the side support member 32a. When the overlapping region d is smaller than 0.5 mm, the glass substrate 31 is likely to be detached from the groove 32a due to shaking when the glass substrate 31 is conveyed by the holding jig 30, and the end surface of the glass substrate 31 may be scratched. There is. When the overlapping region d is larger than 5 mm, the chemical strengthening solution remaining in the overlapping region between the glass substrate and the side support member 32a of the holding jig in the chemical strengthening solution soaking step may be removed in the water soaking step. It can be difficult.
Moreover, it is preferable that the cross-sectional shape of the groove | channel 34a of the side part support member 32a is a U-shape. By making it U-shaped, even if the edge of the outer peripheral end of the glass substrate 31 and the groove 34a are in strong contact, the occurrence of cracks, scratches and cracks at the end of the glass substrate can be suppressed. The shape of the bottom portion other than the flat portions parallel to each other in the U-shape is a flat shape in FIG. 5B, but may be a concave shape in the direction of the central axis of the side support member 32a. It may be convex. The bottom may be V-shaped or arc-shaped.
Moreover, it is preferable that the inner distance L of the two side part support members 32a in FIG. 5A and the outer diameter G of the glass substrate 31 have a relationship of 0.2 mm ≦ LG ≦ 5.0 mm. If it is less than 0.2 mm, the gap between the outer peripheral end of the glass substrate 31 and the side support member 32a is narrow, so when inserting the glass substrate 31 between 32a, a strong pressure may be applied to the glass substrate 31. There is a risk of causing cracks, scratches, or cracks at the ends of the glass substrate 31. On the other hand, if it exceeds 5.0 mm, the distance between the glass substrate 31 and the side support member 32a is too wide, and there is a possibility that the glass substrate cannot be stably held.

Further, the lower support member 32b may have a configuration in which the cross-sectional shapes of the grooves 34b are parallel to each other like the side support member 32a, but the following configuration is preferable.
That is, when the two corners of the outer peripheral edge of the glass substrate 31 are chamfered and the angle formed by the processed surface is θ2, the cross-sectional shape of the groove provided in the lower support member 32b is V-shaped as shown in FIG. The V-shaped angle θ1 is preferably in the range of the following formula.

θ2 <θ1 <170 °
By setting the V-shaped angle θ1 of the V-shaped groove 34b within this range, the place where the chamfered portion 33 at the outer peripheral end of the glass substrate 31 contacts the lower support member 32b is the outermost portion of the chamfered portion 33. The contact is made at the portion P1, and there is no contact with the recording surfaces S1, S2 of the glass substrate 31. Further, the outer peripheral end surface 35 (flat portion having a thickness H) of the glass substrate 31 does not adhere to the groove 34b of the lower support member 32b. Therefore, even if the chemical strengthening step in the manufacturing process of the glass substrate for recording medium is performed, the glass substrate 31 is not scratched or distorted, and even if a slight scratch occurs at the contact portion P1, the recording surface It is possible to manufacture a glass substrate 31 with good quality without scratching S1 and S2.

  When the V-shaped angle θ1 is smaller than the chamfering angle θ2, the groove 34b comes into contact with the boundary portion P2 between the chamfered portion 33 of the glass substrate 31 and the recording surfaces S1 and S2, as shown in FIG. If slight scratches occur at the contact portion P2, the recording surfaces S1 and S2 may be scratched.

  Further, when the V-shaped angle θ1 of the V-shaped groove 34 is 170 ° or more, the glass substrate 31 is liable to be shifted to the side unless the pitch with the horizontal groove is wide as shown in FIG. In some cases, the glass substrate 31 moves over the crest between the grooves to the adjacent groove and comes into contact with the adjacent glass substrate to scratch the recording surfaces S1 and S2.

  The V-shaped angle θ1 is preferably 110 ° to 160 °. By setting this range, the recording surfaces S1 and S2 are less likely to be scratched.

  In addition, when the outer peripheral end of the glass substrate 31 is rounded as shown in FIG. 9, the V-shaped angle θ1 of the groove 34b of the lower support member 32b is preferably 90 ° to 170 °. By doing so, the rounded curved surface portion 36 of the glass substrate comes into contact with the cross section of the groove 34b of the lower support member 32b, and is slightly scratched at the contact portion between the curved surface portion 36 and the groove 34b. Even if this occurs, the recording surfaces S1 and S2 are not scratched. In addition, when the V-shaped angle θ1 of the V-shaped groove 34b is 170 ° or more, the glass substrate 31 is liable to be displaced laterally unless the pitch with the horizontal groove is widened. May move to the adjacent groove and contact the adjacent glass substrate to scratch the recording surfaces S1 and S2.

Also, as shown in FIG. 10, when the cross-sectional shape of the lower support member 32b groove 34b is an arc shape, the chamfered portion of the glass substrate 31 is chamfered at two locations on the outer peripheral end portion of the glass substrate 31. It is preferable that the cross section of the groove 34b has an arcuate shape so that the outer end P1 of the groove 34b contacts the arcuate cross section of the groove 34b of the support member 32b. That is, the radius of curvature R1 of the groove 34b is set so that the boundary position P2 between the recording surfaces S1 and S2 of the glass substrate 31 and the chamfered portion does not contact the groove 34b of the lower support member 32b. By doing so, even if a slight scratch is generated at the contact portion between the outer end P1 of the chamfered portion of the glass substrate 31 and the groove 34b, the recording surfaces S1 and S2 are not scratched.
As shown in FIG. 11, when the outer peripheral end of the glass substrate 31 is rounded and the groove 34b of the lower support member 32b has an arc shape, the radius of curvature of the outer peripheral end of the glass substrate 31 is R2 is preferably larger than R2 when R1 is the radius of curvature of the arc of the groove 34b of the lower support member 32b. By doing so, the round processed surface at the outer peripheral end of the glass substrate 31 and the groove 34b come into contact with each other, and even if a slight scratch occurs at the contact portion, the recording surfaces S1 and S2 can be scratched. Absent. Moreover, if the curvature radius R1 of the cross section of the groove 34b of the lower support member 32b is smaller than the curvature radius R2 of the outer peripheral end portion of the glass substrate 31, the lower support member 32b cannot hold the glass substrate 31 stably. Further, when R2 is larger than R1, the thickness of the glass substrate 31 is thin and may fit into the groove 34b. However, the boundary position P3 between the recording surfaces S1 and S2 of the glass substrate 31 and the round processed surface is the groove. 34b, and even if a slight scratch occurs at the contact portion, the recording surfaces S1 and S2 are scratched, which is not preferable. Further, when the curvature radius R1 of the cross section of the groove 34b of the lower support member 32b is equal to the curvature radius R2 of the outer peripheral end portion of the glass substrate 31, the groove 34b and the outer peripheral end portion of the glass substrate 31 are in surface contact and chemically strengthened. After the temperature is raised in the process, when the glass substrate 31 is cooled to a low temperature, the outer peripheral end of the glass substrate 31 may be distorted and may be damaged.

  As described above, by making the shape of the groove 34a of the side support member 32a according to the present invention, it is possible to prevent the glass substrate 31 from being cracked, scratched or broken.

  In the above, although the process using the holding jig 30 is the chemical strengthening liquid immersion process in the chemical strengthening process and the subsequent water immersion process, it is used in the case of immersing in water in the cleaning process before the chemical strengthening liquid immersion process. be able to.

As a material constituting the holding jig 30, for example, in a metal system, tool steel (steel material containing 0.3 to 2.0% carbon), pure iron, pure aluminum, pure titanium, titanium alloy, magnesium alloy, Zirconium, Inconel HX (heat resistant special steel), nickel, SUS304, SUS316, SUS310S, SUS329, SUS410, SUS430, and the like. In the ceramic system, silicon nitride (Si ₃ N ₄ ), silicon carbide (SiC), aluminum nitride, boron nitride, alumina, mullite (3Al ₂ O ₃ · 2SiO ₂ ), zirconia (ZrO ₂ ), cordierite, macerite ( Machinable ceramics). In addition, there is quartz glass. When a holding jig is constituted using these materials, it is preferable to suppress thermal deformation of the holding jig in consideration of the thermal expansion coefficient of each member constituting the holding jig.

  The material constituting the holding jig 30 is more preferably a material having excellent corrosion resistance against a high-temperature chemical strengthening solution and having a low dust generation property that does not generate fine powder. Since the corrosion resistance is excellent, the durability of the holding jig 30 is improved, and generation of fine powder due to corrosion is suppressed. Moreover, generation | occurrence | production of the foreign material adhering to a glass substrate by being immersed in a chemical strengthening liquid or washing | cleaning water can be suppressed because dust generation property is low.

(Chemical strengthening liquid immersion process)
In the chemical strengthening solution immersion step, the glass substrate 31 is immersed in a chemical strengthening solution in which the chemical strengthening agent is melted, and the alkali metal ions on the surface of the glass substrate are ion-exchanged with the alkali metal ions of the chemical strengthening solution.

As the chemical strengthening agent, conventionally known ones can be used, and examples thereof include potassium nitrate (KNO ₃ ), sodium nitrate (NaNO ₃ ), potassium carbonate (K ₂ CO ₃ ) and the like. These can be used alone or in combination of two or more. To use.

  The chemical strengthening agent is charged into a chemical strengthening treatment tank in a predetermined amount and heated to melt and become a chemical strengthening liquid. The heating temperature of the chemical strengthening solution is preferably in the range of 280 ° C. to 660 ° C., more preferably in the range of 300 ° C. to 450 ° C., from the viewpoint of ion exchange rate and Tg (glass transition temperature) of the glass substrate. By setting this high temperature side (upper limit) to a range of 300 ° C. to 450 ° C. lower than the glass transition temperature Tg, the reaction rate of ion exchange is not too slow, and the shape of the glass substrate is not affected.

  The time for immersing the glass substrate 31 in the chemical strengthening solution is preferably in the range of 0.1 hour to several tens of hours. Moreover, as shown in this example, it is preferable to preheat the glass substrate 31 before immersing it in the chemical strengthening solution. When the glass substrate 31 is heated in advance, when the glass substrate 31 is immersed in the chemical strengthening solution, the temperature of the chemical strengthening solution does not decrease excessively and chemical strengthening can be performed efficiently.

  The thickness of the reinforcing layer is preferably in the range of about 5 μm to 15 μm in view of improving the strength of the glass substrate 31 and shortening the time for the polishing process.

(Water immersion process)
After immersing the glass substrate 31 in the chemical strengthening solution, the glass substrate 31 is continuously immersed in water in order to remove the chemical strengthening solution on the surface of the glass substrate evenly. By immersing the entire glass substrate 31 in water, the chemical strengthening liquid does not partially exist on the glass substrate, and chemical strengthening does not proceed partially. For this reason, since there is no unevenness in chemical strengthening, the glass substrate 31 can have a uniform strength.

  The crystal strengthening liquid or the salt crystal forming the chemical strengthening liquid can be efficiently removed from the surface of the glass substrate 31 in a shorter time as the temperature of the immersion water is increased. The temperature of such water is preferably 35 ° C. to 100 ° C. under atmospheric pressure. The time for immersing the glass substrate in water is preferably 1 second or longer. If it is less than 1 second, the chemical strengthening solution on the glass substrate cannot be sufficiently removed, so that the chemical strengthening solution remains on the glass substrate and unevenness of strengthening occurs. The upper limit of the time for immersing in water is not particularly limited, and may be appropriately determined in consideration of productivity.

  In addition, in order to reduce the temperature difference so that the glass substrate does not crack or crack in the water immersion process due to the temperature difference between the water temperature and the chemical strengthening liquid, between the chemical strengthening liquid immersion process and the water immersion process. A cooling step for cooling the glass substrate 31 may be provided.

(Glass substrate)
The glass substrate 31 to be chemically strengthened is not particularly limited, but soda lime glass mainly composed of silicon dioxide, sodium oxide, calcium oxide; silicon dioxide, aluminum oxide, R ₂ O (R = K, Na, Li) Borosilicate glass; lithium oxide-silicon dioxide glass; lithium oxide-aluminum oxide-silicon dioxide glass; R'O-aluminum oxide-silicon dioxide glass (R '= Mg, Ca Sr or Ba) may be used, and these glass materials may be added with zirconium oxide, titanium oxide or the like.

  The size of the glass substrate 31 is not limited, and the method of the present invention can be applied to a small-diameter disk of 2.5 inches, 1.8 inches, 1 inch, 0.85 inches or less, and the thickness thereof. It can be applied to a thin type having a thickness of 2 mm, 1 mm, 0.63 mm, or less.

  In the glass substrate 31 provided in the chemical strengthening step, the roughness of the main surface and the end face portion is not particularly limited, but the surface roughness of the main surface of the glass substrate 31 is Rmax (maximum height) of 10 nm or less, Ra (Center line average roughness) is preferably 1.0 nm or less. The surface roughness of the end face is preferably in the range of Rmax from 0.01 μm to 1 μm and Ra in the range of 0.001 μm to 0.8 μm. When the glass substrate 31 whose surface is polished is chemically strengthened, the reinforcing layer can be formed uniformly.

(recoding media)
Next, a recording medium using the recording medium glass substrate described so far will be described. When this recording medium glass substrate is used, durability and high recording density are realized. Hereinafter, a recording medium will be described with reference to the drawings.

  FIG. 12 is a perspective view of the magnetic disk. In the magnetic disk DI, a magnetic film 2 is directly formed on the surface of a circular recording medium glass substrate 1. As a method for forming the magnetic film 2, a conventionally known method can be used. For example, a method in which a thermosetting resin in which magnetic particles are dispersed is spin-coated on a substrate, or a method by sputtering or electroless plating is used. A method is mentioned. The film thickness by spin coating is about 0.3 μm to 1.2 μm, the film thickness by sputtering is about 0.04 μm to 0.08 μm, and the film thickness by electroless plating is 0.05 μm to 0.1 μm. From the viewpoint of thinning and densification, film formation by sputtering and electroless plating is preferable.

The magnetic material used for the magnetic film is not particularly limited, and a conventionally known material can be used. However, in order to obtain a high coercive force, Ni having a high crystal anisotropy is basically used, and Ni or A Co-based alloy to which Cr is added is suitable. Specific examples include CoPt, CoCr, CoNi, CoNiCr, CoCrTa, CoPtCr, and CoNiPt containing Co as a main component, CoNiCrPt, CoNiCrTa, CoCrPtTa, CoCrPtB, and CoCrPtSiO. The magnetic film may have a multilayer structure (for example, CoPtCr / CrMo / CoPtCr, CoCrPtTa / CrMo / CoCrPtTa) that is divided by a nonmagnetic film (for example, Cr, CrMo, CrV, etc.) to reduce noise. Addition to the above magnetic material, ferrite, iron - rare-earth or be in a non-magnetic film made of _{SiO 2, BN Fe, Co,} FeCo, etc. granular structure magnetic particles are dispersed, such CoNiPt Also good. Further, the magnetic film may be either an inner surface type or a vertical type recording format.

  In addition, a lubricant may be thinly coated on the surface of the magnetic film in order to improve the sliding of the magnetic head. Examples of the lubricant include those obtained by diluting perfluoropolyether (PFPE), which is a liquid lubricant, with a freon-based solvent.

  Furthermore, you may provide a base layer and a protective layer as needed. The underlayer in the magnetic disk is selected according to the magnetic film. Examples of the material for the underlayer include at least one material selected from nonmagnetic metals such as Cr, Mo, Ta, Ti, W, V, B, Al, and Ni. In the case of a magnetic film containing Co as a main component, Cr alone or a Cr alloy is preferable from the viewpoint of improving magnetic characteristics. Further, the underlayer is not limited to a single layer, and may have a multi-layer structure in which the same or different layers are stacked. For example, a multilayer underlayer such as Cr / Cr, Cr / CrMo, Cr / CrV, NiAl / Cr, NiAl / CrMo, or NiAl / CrV may be used.

Examples of the protective layer that prevents wear and corrosion of the magnetic film include a Cr layer, a Cr alloy layer, a carbon layer, a hydrogenated carbon layer, a zirconia layer, and a silica layer. These protective layers can be formed continuously with an in-line type sputtering apparatus, such as an underlayer and a magnetic film. In addition, these protective layers may be a single layer, or may have a multilayer structure including the same or different layers. Note that another protective layer may be formed on the protective layer or instead of the protective layer. For example, in place of the protective layer, tetraalkoxysilane is diluted with an alcohol-based solvent on the Cr layer, and then colloidal silica fine particles are dispersed and applied, and then baked to form a silicon dioxide (SiO ₂ ) layer. It may be formed.

  The magnetic disk has been described above as one embodiment of the recording medium. However, the recording medium is not limited to this, and the glass substrate of the present invention can be used for a magneto-optical disk, an optical disk, and the like.

(Examples 1 to 10)
As a glass substrate for chemical strengthening, an aluminosilicate glass substrate having an outer diameter of φ1 = 65 mm, an inner diameter of φ2 = 20 mm, and a plate thickness d = 0.635 mm is prepared, and the outer peripheral end portions are chamfered as shown in FIG. processed. A sample with a chamfering angle of 90 ° was prepared, leaving a flat portion thickness H = 0.3 mm on the end face. Further, as the holding jig, a holding jig that holds the glass substrate using one lower support member and two side support members was used. The cross-sectional shape of the side support member was a U-shape as shown in FIG. 5, and the values shown in Table 1 were the outer diameter of 14 mm, the groove outer diameter of 7 mm, the flat portion interval D, and the flat portion length d0. The pitch of each groove was 6.5 mm. The groove shape of the lower support member was the one shown in FIG. 6, and the V-shaped angle θ1 was 110 °. The outer diameter of the lower support member is φ14 mm. SUS304 was used for all the materials constituting the holding jig.

100 glass substrates described above were stored in a holding jig, preheated to 350 ° C., and then immersed in a chemical strengthening solution for 15 minutes. As the chemical strengthening solution, a chemical strengthening agent containing NaNO ₃ and KNO ₃ in a mass ratio of 1: 9 was charged into a chemical strengthening tank and heated to 330 ° C. In the overlapping region d between the glass substrate and the side part indicating member, the glass substrate was biased to one of the two side supporting members and overlapped with the flat part length d0.

  After dipping in a chemical strengthening solution, 100 chemically strengthened glass substrates were immersed in water containing alkali metal ions at 60 ° C. for 5 minutes while being stored in a holding jig, and then dried.

The glass substrate was taken out from the holding jig, and the glass substrate was visually or visually checked with a magnifying glass to check for cracks, cracks, color change, and the presence of the chemical strengthening solution. Even if one of the 100 sheets is cracked or cracked, X indicates that one of the 100 sheets is color-changed, △ indicates that all 100 glass substrates are cracked, cracked, or has no color change, ○ Evaluation was made by assuming that the remaining chemical strengthening solution was x, Δ was slightly remaining, and ○ was not left. X Evaluation is a level that cannot be used as a glass substrate for a recording medium, and Δ and ○ evaluations can be used.
(Comparative Example 1)
Comparative Example 1 was prepared and evaluated under the same conditions as in Example 3 except that the side support member grooves were V-shaped as shown in FIG. 4 and θ was 90 °.

  Table 1 shows the evaluation results.

  In the result of Table 1, when Example 3 and Comparative Example 1 are compared, in Comparative Example 1, the cross-sectional shape of the side support member is V-shaped. It can be seen that, when the cross-sectional shape of the side support member is a shape having flat portions parallel to each other as in Example 3, a good glass substrate free from scratches and cracks can be produced. Moreover, when Examples 1-5 are compared, it turns out that 1-2 mm is preferable for the space | interval D of the flat part mutually parallel of a side part supporting member. Moreover, when Examples 6-10 are compared, it turns out that 0.5-5 mm is preferable for the area | region with which a side part supporting member and a glass substrate overlap.

Claims (13)

In the holding jig for holding the glass substrate used in the process of chemical strengthening by immersing the glass substrate in the chemical strengthening liquid,
The holding jig includes a plurality of support members and a pair of fixing members to which the support members are attached, and the plurality of support members include a plurality of grooves for supporting the glass substrate. A lower support member that supports the lower part of the substrate, and a side support member that supports the side part of the glass substrate,
A holding jig having flat portions in which the cross-sectional shapes of the grooves of the side support members are parallel to each other. The holding jig according to claim 1, wherein an entrance of a groove of the side support member is chamfered. The holding jig according to claim 1 or 2, wherein an interval between flat portions of the side support member grooves parallel to each other is 1 to 2 mm. The region where one of the flat portions parallel to each other of the grooves of the side support member and the side portion of the glass substrate overlap is 0.5 to 5 mm. 4. The holding jig according to any one of the third item. An inner distance L indicating the side of the glass substrate between the two side support members arranged opposite to each other and an outer diameter G of the glass substrate are 0.2 mm ≦ LG ≦ 5. The holding jig according to any one of claims 1 to 4, wherein the holding jig has a relationship of 0 mm. The holding jig according to any one of claims 1 to 5, wherein a cross-sectional shape of the groove of the side support member is a U-shape. When the cross-sectional shape of the groove of the lower support member is V-shaped, the outer peripheral end of the glass substrate is chamfered at two locations, and the angle formed by the two processed surfaces after chamfering is θ2. The holding jig according to any one of claims 1 to 6, wherein the V-shaped angle θ1 is within a range of the following formula.
θ2 <θ1 <170 ° The cross-sectional shape of the groove of the lower support member is V-shaped, the outer peripheral end of the glass substrate is rounded, and the V-shaped angle θ1 is 90 ° to 170 °. The holding jig according to any one of claims 1 to 6, wherein: A cross-sectional shape of the groove of the lower support member is an arc shape, two outer peripheral end portions of the glass substrate are chamfered, and an outer end of the chamfered portion of the glass substrate is chamfered. The holding jig according to any one of claims 1 to 6, wherein the holding jig is in contact with a cross section. The cross-sectional shape of the groove of the lower support member is an arc shape with a radius of curvature R1, the outer peripheral end of the glass substrate is rounded, and when the radius of curvature of the outer peripheral end is R2, R1 is R2. The holding jig according to any one of claims 1 to 6, wherein the holding jig is larger than the holding jig. In the manufacturing method of the glass substrate for recording media which has the process of chemically strengthening a glass substrate,
A manufacturing method of a glass substrate for a recording medium, wherein the manufacturing method is performed using the holding jig according to any one of claims 1 to 10. A glass substrate for a recording medium, which is manufactured using the method for manufacturing a glass substrate for a recording medium according to claim 11. A recording medium comprising a magnetic film on a surface of the glass substrate for a recording medium according to claim 12.