JPH03224144A - Optical disk substrate - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Summary] Regarding an optical disc substrate using an aluminum alloy base material, it is an object of the present invention to provide an optical disc substrate in which the adhesion between the aluminum alloy base material and the group forming resin layer is further improved. An aluminum alloy disk base material whose surface has been roughened by treatment, and a group bonded to the roughened surface of this base material via a coupling agent that has affinity for both inorganic and organic materials. and a forming resin layer.

[Industrial application field]

The present invention relates to an optical disc substrate using an aluminum alloy base material. More specifically, the present invention relates to optical discs that include both narrowly defined optical discs that record signals in the form of holes (bits) or not, and magneto-optical discs that record signals with or without magnetization reversal of a magnetic film. The present invention relates to an optical disc substrate using an aluminum alloy base material.

[Conventional technology]

An optical disk is an information recording memory comprising a recording film and a protective film on a substrate having a guide groove (pre-group).

Conventional optical disks have used transparent resin (eg, polymethyl methacrylate, polycarbonate, etc.) or glass as a substrate. The transparent resin substrate used in conventional optical disks has the advantage that spiral or concentric guide grooves can be created from the beginning during molding of the substrate, but has the disadvantage of being prone to warping and waviness. . On the other hand, glass substrates are far superior to resin substrates in terms of quality, as they do not suffer from "warpage" or "waviness" that occurs with resin substrates. However, glass substrates were easily broken and the material cost was high.

Therefore, in order to overcome the above-mentioned difficulties faced by glass substrates, the use of aluminum alloys instead of glass as substrates for optical disks has recently been considered. However, when an aluminum alloy is used as a base material for an optical disk substrate, it tends to peel off due to weak adhesion with the group-forming resin layer formed on the base material.
Furthermore, since it has poor corrosion resistance, there is a need to solve this problem.

[Problem to be solved by the invention]

Therefore, an object of the present invention is to provide an optical disc substrate with improved adhesion between an aluminum alloy base material and a group-forming resin layer.

[Means to solve the problem]

The optical disc substrate of the present invention includes an aluminum alloy disc base material whose surface has been roughened by treatment, and a coupling agent having affinity for both inorganic and organic materials on the roughened surface of this base material. and a bonded group-forming resin layer.

The disc base material used in the optical disc substrate of the present invention is
For example, an aluminum alloy base material used as a substrate of a magnetic disk as specified in JIS-5086 may be used. Such an aluminum alloy base material (hereinafter simply referred to as "aluminum base material") is non-magnetic,
It is lightweight, there is no need to worry about it breaking, and it is much cheaper than glass substrates.

The aluminum base material used is one whose surface on which the recording layer is to be formed has been roughened. Typical surface roughening treatment techniques include alumite method, boehmite method, and sodium carbonate method, which are used to form a base conversion film on the surface of an aluminum base material to improve adhesion with organic materials (paint film). Law, B, V, Law, M, B, V, Law, Snake, I
8. method, Allritta method, Pirumino method, chromic acid method, chromate method, phosphate method, phosphoric acid alcohol method, phosphochromic acid method, and Metsuki technique. More preferred surface roughening treatment methods are the alumite method and the boehmite method, which form an alumina film on the surface of the aluminum base material.

A coupling agent (primer) is located on the roughened aluminum substrate. This coupling agent is
A surface modifier that contributes to improving the adhesion between an inorganic material (aluminum base material subjected to surface roughening treatment) and an organic material (group forming resin).

Such coupling agents are well known, and include, for example, a silane coupling agent represented by the general formula (RO)3SIR' and a titanium-based coupling agent represented by the general formula ROTiR'3. In the coupling agents represented by these general formulas, the moiety represented by the RO group hydrolyzes and reacts with the inorganic surface to chemically bond with an ether bond,
The moiety represented by R' has a strong affinity with organic substances.

Typical examples of coupling agents useful in the present invention include titanate coupling agents (e.g., titanate Preneact® KRII manufactured by Ajinomoto Co., Inc., the chemical name of which is isopropyl isostearoyl diacryl titanate). , silane coupling agents (e.g. vinyltrichlorosilane, vinyltrimethoxysilane),
An aluminum-based coupling agent (eg acetalkoxyaluminum diisopropylate).

The group-forming resin layer is bonded to the base material via a coupling agent. This resin is a group-forming resin that has affinity with the coupling agent on the base material, and is generally cured by ultraviolet light. Any type of group-forming resin may be used as long as it satisfies the above conditions, but the part (R' group in the above general formula) that shows affinity with the organic substance of the coupling agent is, for example, an acrylic group. In this case, an acrylic resin such as a polyfunctional (bifunctional or higher) ester acrylate resin is suitable.

When manufacturing the optical disk substrate of the present invention (a schematic cross-sectional view thereof is shown in FIG. 1), first, the surface of the aluminum base material 1 is subjected to, for example, a boehmite treatment to form a boehmite film 2, and the surface of the base material is roughen the surface. The thickness of the coating is generally from 0.5 to 2-1, preferably around 1 layer. Also,
The average surface roughness of this film is 0.2 to 0.61 M, preferably 0.3 to 0.4 M. Next, a coupling agent is applied onto the roughened surface of the base material and thoroughly dried to remove the solvent. Next, a group forming resin is applied onto the coating film 3 of the coupling agent and cured.

The thickness of the group forming resin layer 4 is generally 10 to 201-
It is. Although no groups are shown in the group forming resin layer of the optical disc substrate of the present invention shown in FIG.
When actually producing an optical disc using the optical disc substrate of the present invention, groups should be formed in this layer (
It goes without saying that, for example, by pressing the master disc).

[For production]

The roughened surface of the aluminum base material improves the adhesion between the base material and the group-forming resin layer bonded thereon via a coupling agent. The improvement in adhesion in this case is due to the mechanical (physical) bond between the base material and the resin layer.

The coupling agent on the inorganic porous roughening film has a part in its molecule that chemically bonds with the inorganic material and a part that has an affinity for the organic material, so when it is applied to the inorganic surface, it chemically bonds with the surface. Then, a film that is easily compatible with organic substances is formed, and the group-forming resin layer formed on this film is strongly bonded to the aluminum base material.

In this way, in the optical disc substrate of the present invention,
In addition to the physical bond created by the roughening of the aluminum base material, a stronger chemical bond is added by the coupling agent, resulting in a significant improvement in the adhesion between the base material and the group-forming resin layer.

〔Example〕

Next, the optical disc substrate of the present invention will be explained with reference to Examples.

Example 1 An 8-inch (approximately 20 cm) diameter disk substrate made of an aluminum alloy with a magnesium content of 5% or less was used as a base material. This substrate was immersed in a solution of ion-exchanged water with 0.5% triethanolamine added, and boiled in the air for about 30 minutes to form a boehmite film about 1-thick on the surface of the substrate. The surface was roughened. When the roughness of the surface of the base material subjected to surface treatment in this way was measured using a surface roughness meter, the average roughness was 0.32-1, the maximum roughness was 2,
It had two layers. Figures showing the surface roughness of the aluminum base material before and after the surface roughening treatment are shown in Figures 2 and 3, respectively.

In these figures, one scale on the vertical axis is 0.51! Ia,
One scale on the horizontal axis corresponds to 500 warehouses.

Next, a 5% xylene solution of a coupling agent (KR11, a titanate-based coupling agent manufactured by Ajinomoto Co., Ltd.) was applied to this base material using a spin cord method, and the xylene solvent was thoroughly dried to remove the xylene solvent. Since this coating of coupling agent is very thin, most of the roughened surface of the aluminum alloy substrate remains intact.

On top of this coupling agent, a photopolymer for transfer (trifunctional acrylic ester SH00 manufactured by Mitsubishi Yuka Co., Ltd.
2) was applied and cured by irradiation with ultraviolet rays.

Example 2 The same aluminum alloy base material as in Example 1 was used. This base material was placed in a high-pressure cooker containing a solution of 0.5% triethanolamine added to ion-exchanged water, and heated at 120°C for 2 hours.
A boehmite film with a thickness of about IJs was formed on the surface of the substrate by treatment at atmospheric pressure for 1 hour, and the surface was roughened. A 5% xylene solution of KR11 coupling agent manufactured by Ajinomoto Co., Ltd. was applied to this base material, and the solvent was removed by evaporation. On the coating film of this coupling agent, transfer photopolymer (SH manufactured by Mitsubishi Yuka Co., Ltd.)
002) was applied and cured with ultraviolet light to form a group-forming resin layer.

An adhesion peel test was conducted on the optical discs manufactured in Examples 1 and 2 to examine the adhesion between the aluminum alloy base material and the group-forming resin layer. In this test, as shown in FIG. 4, a tensile jig 11 made of aluminum alloy and having a contact surface of 20 mmφ was used.
With the contact surface of this jig and the group-forming resin layer 13 of the disk base material 12 adhesively fixed with the epoxy adhesive 14, a tensile test was conducted using an adhesion tester. The portion of the resin layer that is bonded to the jig with an adhesive was previously cut with the same diameter of 20 mm as the jig, and the force with which this portion was peeled off from the base material was measured. Table 1 shows the results. For comparison, this table shows the group-forming resin layer (Example 1 The results of the peel test for the same resin layer as in Example 2 and Example 2 are also shown.

Table 1 Adhesion Peeling Test Results As shown above, the optical disc of the present invention has an aluminum base material surface roughened and a group forming resin layer bonded to this base material via a coupling agent. The adhesion between the substrate and the group-forming resin layer is clearly improved compared to an optical disk substrate in which only the surface of the substrate is roughened. The adhesion between the base material and the group-forming resin layer in the optical disc substrate of the present invention greatly exceeds that (peel strength of about 30 kg/cnf) when a conventional glass substrate is used.

〔Effect of the invention〕

In the optical disc substrate of the present invention, the inorganic base material and the organic resin layer are bonded together by a coupling agent present between the aluminum base material whose surface has been roughened and the group-forming resin layer. are strongly chemically bonded. That is, the adhesion between the inorganic base material and the organic resin layer is significantly improved. For this reason, "warpage" and "undulation"
It is possible to provide a practical optical disc substrate that does not undergo such deformation and is free from the risk of cracking.

[Brief explanation of drawings]

FIG. 1 is a schematic cross-sectional view of the optical disk substrate of the present invention, FIG. 2 is a diagram showing the surface roughness of an aluminum base material that has not been roughened, and FIG. 3 is a diagram showing the surface roughness of an aluminum base material that has been roughened. FIG. 4 is a diagram illustrating the adhesion test method. In the figure, 1 and 12 are aluminum base materials, 2 is a boehmite film, 3 is a coupling agent, and 4 and 13 are group-forming resin layers.

Claims (3)

[Claims] 1. An aluminum alloy disk base material whose surface has been roughened by treatment, and a group-forming resin bonded to the roughened surface of this base material via a coupling agent that has affinity for both inorganic and organic materials. An optical disc substrate characterized by having a layer. 2. 2. The optical disc substrate according to claim 1, wherein the surface of the aluminum alloy disc base material is roughened by alumite treatment or boehmite treatment. 3. 2. The optical disc substrate according to claim 1, wherein the coupling agent is a titanate coupling agent, a silane coupling agent, or an aluminum coupling agent.