JPH03162741A - Magneto-optical recording medium and its production - Google Patents

Abstract

PURPOSE:To obtain a magneto-optical recording medium showing little dimensional change and high shock resistance by forming a silicon dioxide film on a synthetic resin substrate. CONSTITUTION:A synthetic resin substrate is subjected to primer treatment by applying a n-hexane solution of silane on both sides of the substrate and blowing hot air to dry the surfaces, on which silicon dioxide films are precipitated with an equipment for formation of silicon dioxide films. The film-forming equipment has a dipping tank comprising an outer tank and inner tank, between which water is contained and heated while stirred with a stirrer to maintain uniform temp. distribution. The inner tank is charged with the reaction liquid comprising an aqueous solution of hydrosilicofluoric acid diluted with water, into which an aqueous solution of boric acid is dropped to obtain such a liquid having proper saturation of silicon dioxide. After dipping the substrate in the liquid of the inner tank, the liquid is supplied with boric acid, circulated and filtered. By using the synthetic resin substrate thus covered with silicon dioxide, the obtd. magneto-optical medium shows little dimensional change and has high shock resistance.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a magneto-optical recording medium, and more particularly to a magneto-optical recording medium that has little change in shape and is resistant to impact, and a method for manufacturing the same. [Prior Art] Conventionally, as a technique for providing a magneto-optical recording medium that has little change in shape and is strong against impact, for example, Japanese Patent Laid-Open No. 61-11948
The technique described in the above publication is known.

In this technique, a metal substrate is provided as an auxiliary substrate on the opposite side of the magneto-optical recording medium from the side having the transparent substrate. In addition, in a double-sided recording type magneto-optical recording medium, a magneto-optical recording layer is formed on both sides of a metal substrate as an auxiliary substrate,
A transparent substrate is further provided on the surface of each magneto-optical recording layer.

[Problem B to be solved by the invention] However, in the magneto-optical recording medium described in the invention described in JP-A-61-11948, a metal substrate such as AIFe was used as the auxiliary substrate. The problem has been that the weight of the magneto-optical recording medium becomes very large. For example, the specific gravity of /l is 2.7 and the specific gravity of Fe is very large, 7.9, so the magneto-optical recording medium is large (large diameter).
This increases the load placed on each spindle mode of the magneto-optical disk drive, so it is necessary to use a spindle motor with a large torque (and therefore a large size). The drive can be made more compact. Furthermore, since metal substrates have high thermal conductivity, when writing data, the temperature of the magneto-optical recording layer is difficult to rise even though the temperature of the magneto-optical recording layer is increased by irradiating the laser beam1. Another issue was the need to increase the power of the laser beam. Increasing the power of the laser beam may shorten the life of the laser device and increase power consumption.

It is an object of the present invention to solve the problems of the prior art as described above, and to provide a magneto-optical recording medium that has little change in shape, is strong against impact, is lightweight, and has low thermal conductivity.

[Means for Solving the Problems] The gist of the present invention is to provide a transparent substrate, a magneto-optical recording layer formed on the transparent substrate and including at least one or more recording layers, and a magneto-optical recording layer formed on the transparent substrate. It is an object of the present invention to provide a magneto-optical recording medium characterized in that it has at least a synthetic resin substrate on both sides of which a silicon dioxide coating is formed, and a method for manufacturing the same.

Each component of the present invention will be explained below.

(Transparent Substrate) In the present invention, there are no particular limitations on the material, shape, etc. of the transparent substrate. For example, any transparent substrate conventionally used for magneto-optical recording media, such as glass substrates and polycarbonate substrates, can be used, and any material can be selected as long as the object of the present invention can be achieved.

(Magneto-optical recording layer) In the present invention, the structure of the magneto-optical recording layer is not particularly limited, as long as it has at least a recording layer. For example, a dielectric layer, a protective layer, a light reflective layer, etc.
or more than one. Furthermore, there is no problem in having layers for other purposes. As the recording layer, any material can be used as long as it functions as a recording layer of a magneto-optical recording medium. For example, TbFeCo, GdFe, TbCo, DyFe,
NdDyFeCo, TbFe, GdFeBi, GdTb
Recording materials such as Fe can be used. Note that the recording layer is not limited to one layer, and may be of a type in which multiple layers are formed with dielectric layers interposed therebetween. Furthermore, it may be of a double-sided recording type. ．． As the dielectric layer, protective layer, light reflective layer, etc., all those conventionally used in magneto-optical recording media can be used. For example, Si,A/! , Mg, Ca, Ti,
Zr. ．． A layer made of a compound such as Zn can be used and can be arbitrarily selected as long as the object of the present invention can be achieved.

(Synthetic resin substrate) In the present invention, a synthetic resin substrate that can be suitably used must have rigidity. The rigidity of a synthetic resin substrate is determined by the type and thickness of the synthetic resin used. Therefore, in the present invention, the thickness of the synthetic resin substrate used is determined by the required rigidity and the type of synthetic resin.

Examples of the types of synthetic resins used in the present invention include:
Examples include nylon 66, glass fiber-reinforced nylon 66, nylon 612, boria ξ-d, polyethylene terephthalate, polyether ξ-d, amorphous polyolefin, polycarbonate, and the like.

(Ultraviolet curable resin) In the present invention, it is preferable to have an ultraviolet curable resin layer between the magneto-optical recording layer and the synthetic resin substrate in order to prevent chemical and physical deterioration of the recording layer.

As a method to prevent chemical and physical deterioration of the recording layer,
A method of providing a thin film of an inorganic material, a method of providing a thermosetting resin layer, a method of providing an ultraviolet curable resin layer, etc. can be used. However, when providing a thin film of an inorganic substance, the thickness M must be on the order of microns, and therefore a sputtering method or the like must be used. In this case, manufacturing time increases and manufacturing costs increase.

Furthermore, when a thermosetting resin layer is provided, it is necessary to expose the entire magneto-optical recording medium to high temperatures during curing, which tends to cause deformation of the transparent substrate or synthetic resin substrate, and further increases the curing time.

On the other hand, when providing an ultraviolet curable resin layer, it can be cured at room temperature, and the ultraviolet irradiation time is only a few tens of seconds, so the transparent substrate or synthetic resin substrate is hardly deformed and can be easily cured during the process. Sex is also good. Therefore, it is most desirable to use an ultraviolet curing resin.

The thickness of the ultraviolet curable resin layer is preferably 10-15 μm. This is because if the thickness is less than 10 μm, chemical and physical deterioration of the recording layer cannot be sufficiently prevented, and if it is thicker than 20 μm, deformation of the transparent substrate or synthetic resin substrate cannot be ignored.

(Method for forming a silicon dioxide film) In the present invention, a silicon dioxide film is formed on both sides of a synthetic resin substrate.

As a method for forming the silicon dioxide film, ordinary thin film forming techniques such as vapor deposition, spuntering, CVD, and liquid phase growth can be used. Among these, the precipitation method, in which a synthetic resin substrate is immersed in a supersaturated hydrofluorosilicic acid solution of silicon dioxide to deposit a silicon dioxide film, is easy to work with and can form a uniform and dense film. Particularly preferred.

As for this precipitation method, a known method disclosed in detail in JP-A-61-12734 can be applied. A supersaturated hydrofluorosilicic acid solution of silicon dioxide is a hydrofluoric acid solution containing silicon dioxide (silica gel, Aerosil, silica glass, other silicon dioxide-containing substances, etc.)
After dissolving the silicon dioxide, water or a reagent (boric acid, aluminum chloride, etc.) is added to create a supersaturated state of silicon dioxide. The synthetic resin substrate may be brought into contact with this treatment liquid. Contact can be made by immersing the synthetic resin substrate in the processing solution, or
Although there are methods such as allowing a treatment liquid to flow down onto the surface of the synthetic resin substrate, a dipping method is preferable in order to form a uniform film.

The concentration of hydrofluorosilicic acid in the treatment liquid is 1 to 2 mol/2
It is preferable to use a hydrofluorosilicic acid aqueous solution with a concentration of more than 2 mol/l to saturate silicon dioxide and then dilute it with water to a concentration of 1 to 2 mol/l. It is preferable because it can be coated. When adding boric acid to create a supersaturated state, the amount added is IXIO-” to 1 mole of hydrosilicic acid in the treatment solution.
40XIO-" moles, preferably 1.2X10-" to 1
A range of 0xIO-'' moles is desirable for forming a fast and homogeneous coating.

While the synthetic resin substrate is immersed in the treatment solution, it is preferable to continuously add and mix the boric acid aqueous solution, circulate the treatment solution, and filter it with a filter in order to efficiently obtain a homogeneous film. . When using silica gel as a source of silicon dioxide, a filter with a pore size of 1.5 μm or less is used; when using other materials such as silica glass, a filter with a pore size of l
A filter with a diameter of 0 μm or less is preferable.

In addition, when placing the treatment liquid in an immersion tank and bringing it into contact with the synthetic resin substrate, it is important to allow the treatment liquid to flow in a laminar flow on the surface of the object being immersed to form an even and homogeneous coating. Preferable for shaping.

The thickness of the silicon dioxide film is not particularly limited and can be determined as appropriate, but usually several hundred to several thousand people can accomplish the purpose of surface modification.

In the present invention, there is no particular problem with the adhesion between the synthetic resin substrate and the silicon dioxide coating, but in order to further strengthen the adhesion between the synthetic resin substrate and the silicon dioxide coating, it is necessary to A brimer layer may be formed on the surface to improve adhesion, or the substrate surface may be treated.

The material and surface treatment method used for the primer layer are not particularly limited.

For example, examples of the primer layer include organosilicon compounds represented by the following formula [1].

(R'). Si (R")4-n [1] (wherein R' is a hydrocarbon group having 1 to 6 carbon atoms, a methacryloxy group, an epoxy group, an amino group, a mercapto group, an isocyano group, an organic group having fluorine or chlorine) (R2 is selected from an alkoxy group, an alkoxyalkoxy group, and a chlorine atom, and may be the same or different from each other, and n represents an integer of 0 to 4.) Organic compound represented by the above formula [1] As a specific example,
Trimethylmethoxysilane, dimedyldimethoxysilane, methyltrimethoxysilane, tetraethoxysilane,
Phenylmethyldimethoxysilane, phenyltrimethoxysilane, T-aminopropyltriethoxysilane, T
-Methacryloxypyltrimethoxysilane, N-
(β-aminoethyl)-γ-acnopropyltriethoxysilane, N-bis-(β-hydroxyethyl-T-aminopropyltriethoxysilane, N-(β-aminoethyl)-T-aminopropyl(methyl)dimethoxy) Silane, T~chloropropyltrimethoxysilane, T-mercaptopropyltrimethoxysilane, 3,3.3-trifluoropropyltrimethoxysilane, T-glydoxypropyltrimethoxysilane, β-(3,4-epoxysilane) Examples include hexyl)ethyltrimethoxysilane, methyltrichlorosilane, dimethylchlorosilane, trimethylchlorosilane, and tetrachlorosilane.

Alternatively, the silicon compound may be an organosilicon compound represented by the following formula [2].

R4-- Si(O O R')- [
2] (wherein R may be the same or different from each other, and is a hydrocarbon group having 1 to 6 carbon atoms, a vinyl group, a methacryloxy group, an epoxy group, an amino group, a mercapto group, an organic group having fluorine or chlorine) and R' may be the same or different from each other and represent an alkyl group, an acyl group, or an arylalkyl group, and m represents an integer of 1 to 4.) of the organic compound represented by the above formula [2] As a specific example,
Vinyltris(t.-butylperoxy)silane, vinyltris(cumemberoxy)silane, vinyltris(acetylbaroxy)silane, vinyltris(penzoylperoxy)silane, vinyltris(lauroylperoxy)silane, γ-glycidoxybropyl Tris (
t-butylperoxy)silane, γ-glycidoxypropyltris(t-cumemberoxy)silane, γ-glycidoxypropyltris(t-acetylperoxy)
Silane, T-glycidoxypropyltris(t-lauroylveroxy)silane, T-glycidoxypropyltris(t-penzoylveroxy)silane, γ-methacrylicpropyltris(t-butylveroxy)silane , T-methacryloxypropyltris(L-cumemberoxy)silane, T-methacryloxypropyltris(t-acetylperoxy)silane, γ-methacryloxypropyltris(t-lauroylperoxy)silane, T- Methacryloxybrobyltris(t-penzoylveroxy)silane and the like can be mentioned.

Alternatively, the silicon compound may be an organosilicon compound represented by the following formula [3].

(R summer) 7 l H. =CH−S i (OR”) 3−. [
3] (wherein, Rl is a hydrocarbon group having 1 to 6 carbon atoms, R2
are selected from an alkoxy group, an alkoxyalkoxy group, and an acetoxy group, and may be the same or different from each other, and n represents an integer of 0 to 3. ) Specific examples of the organic compound represented by the above formula [3] include triethoxy (vinyl)
Silane, trimethoxy(vinyl)silane, ethoxy(dimethyl)vinylsilane, dimethoxy(methyl)vinylsilane, diethoxy(methyl)vinylsilane, dimethoxy(acetoxy)vinylsilane, t. Liptoxy (vinyl) silane, triacetoxy (vinyl) silane, tris(
Examples include β-methoxyethoxy)vinylsilane.

Alternatively, the silicon compound may be an organosilicon compound represented by the following formula [4]. (R4) Hz “C C O R” S i (OR
' ) 3-+1R' O
[4 (wherein R1 is a hydrogen atom or a methyl group, R
2 [1 to 5 carbon atoms (-CH.-) group, R1 is selected from alkoxy group, alkoxyalkoxy group, acetoxy group, and are the same or different from each other. It is a hydrocarbon group, and n represents an integer of O to 3. ) Specific examples of the organic compound represented by the above formula [4] include:
T-methacrylate (trimethoxy)silane,
T-methoxysilane, γ
-Mekkuri mouth fluoropiol (triethoxy) silane,
Examples include T-methacrylate oxybrobyl(diethoxy)methylsilane.

Alternatively, the silicon compound may be an organosilicon compound represented by the following formula [5].

(Left below) (In the formula, R', R'' are the same or different alkoxy groups, alkoxyalkoxy groups or chlorine atoms, R3, R
4 is a substituted or unsubstituted monovalent hydrocarbon group, A is selected from a divalent hydrocarbon group, a divalent organic group containing an oxygen atom or a sulfur atom, and m and n are 1 to 3; Indicates an integer. ) Specific examples of organic compounds represented by the above formula [5] include:
Examples include 1,1,3,3-tetramethyldisiloxane, hexamethyldisilane, hexamethyldisiloxane, and the like.

These organosilicon compounds can be used alone or in combination.

Other examples of compounds forming the primer layer include compounds having at least one amino group, such as aliphatic primary amines, aliphatic secondary amines, aliphatic tertiary amines, aliphatic unsaturated amines, and alicyclic amines. Examples include formula amines, aromatic amines, amino alcohols, and the like.

Specific examples of these compounds having at least I amino groups include methylamine, dimethylamine, ethylamine, diethylamine, isobrobylamine, probylamine, dibropylamine, butylamine,
Diisobutylamine, isobutylamine, sec-butylamine, tert-butylamine, dibutylamine, diisobutylamine, pentylamine, dipentylamine, 2-ethylhexylamine, allylamine, aniline, toluidine, cyclohexylamine, ethylenediamine, brobylenediamine, diethylenetriamine,
Examples include aliphatic amines such as 1,6-hexadiamine and 1,3-propanediamine, aromatic amines, and alicyclic amines. In addition, the amino alcohol is a compound having a 17th amino group or a 27th amino group and a hydroxyl group on different carbon atoms, and specifically, monoethanolamine, 2-aminopropan-1-ol, 1-amino alcohol, etc. Aminopropan-2-ol, 3-aminopropan-1-
Examples include ol, 1-aminobutan-2-ol, 2-aminobucun-2-ol, diethanolamine, N-ethylethanolamine, and the like. These a≧
One type or two or more types of compounds having a group can be used.

The brimer layer made of the organosilicon compound or a compound having at least one adanyl group can be formed by applying a solution dissolved in an organic solvent or the like directly onto a synthetic resin substrate, or by immersing the synthetic resin substrate in the solution. good. Furthermore, in the present invention, a plasma polymerized film of the above compound may be formed by a commonly used plasma polymerization method.

Further, in the present invention, the surface of the synthetic resin substrate may be treated with an acidic solution to modify the surface,
Such acidic solutions include, for example, monochloroacetic acid, dichloroacetic acid, acetic acid, formic acid, propionic acid, acetoacetic acid,
Examples include solutions in which acids such as trichloroacetic acid, trifluoroacetic acid, hydrochloric acid, sulfuric acid, phosphoric acid, chromic acid sulfate, and chromic acid are dissolved in alcohols such as methanol and ethanol, and solvents such as water.

In addition, in the present invention, the surface of the synthetic resin substrate may be subjected to surface modification treatment such as plasma treatment, and by performing such treatment, the silicon dioxide coating and the synthetic resin are formed in the same way as when forming the primer layer. Adhesion to the substrate can be further improved.

[Function 1] According to the present invention, since a synthetic resin substrate whose surface is coated with a silicon dioxide film is used as an auxiliary substrate of the magneto-optical recording medium, the weight of the magneto-optical recording medium can be reduced, and therefore the weight of the spindle motor can be reduced. The load can be reduced and the magneto-optical disk drive can be made more compact.

Further, according to the present invention, since a synthetic resin substrate whose surface is coated with a silicon dioxide film is used as an auxiliary substrate, the thermal conductivity of the magneto-optical disk can be reduced, and therefore, when writing data, the laser light source When the temperature of the magneto-optical recording medium is raised by irradiating it, the temperature tends to rise, and therefore the power of the laser light source can be reduced.

Further, according to the present invention, since a synthetic resin substrate whose surface is coated with a silicon dioxide film is used as an auxiliary substrate, the moisture absorption of the synthetic resin substrate can be extremely reduced. Changes can be significantly reduced. Furthermore, since the surface of the synthetic resin substrate is coated with a dense silicon dioxide film, it is possible to impart a significant scratch resistance effect.

In addition, in the present invention, if a synthetic resin substrate whose surface is coated with a silicon dioxide film with a primer layer made of an organosilicon compound or an amino compound as exemplified above is used, the silicon dioxide film and the synthetic resin substrate can be used. Since the adhesion between the two layers can be further improved, it is possible to provide a magneto-optical recording medium that not only has shape change and scratch resistance over a long period of time, but also has excellent recording and reproducing characteristics even in high temperature and high humidity environments. .

[Examples] Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited only to these Examples.

Example 1 Synthetic resin substrate made of polycarbonate resin (diameter 13
A solution of vinyltris(penzoylperoxy)silane in n-hexane (concentration 1% by weight) was coated on both sides of the sheet (1.2 mm thick and 1.2 mm thick) using a spin coater, and then heated at 60"C.
The material was dried by heating with hot air for 3 minutes. The film thickness of vinyltris(penzoylperoxy)silane after drying is approximately 4
There were 0 people. A silicon dioxide film was deposited on the entire surface of the primer-treated synthetic resin substrate using a silicon dioxide film manufacturing apparatus similar to that described in JP-A-61-12734. That is, the silicon dioxide film manufacturing apparatus has a dipping tank consisting of an outer tank and an inner tank, and the space between the inner tank and the outer tank is filled with water. This water is heated with a heater to a temperature of 35°C, and stirred with a stirrer to make the temperature distribution uniform. The inner tank consists of a front part, a middle part, and a rear part, and each part is filled with an aqueous solution of hydrofluorosilicic acid at a concentration of 2.0 mol/l, in which silicon dioxide is dissolved and saturated, using industrial silica gel powder as a source of silicon dioxide. It is filled with 3 liters of reaction solution diluted twice using At this point, the circulation pump was activated to discharge a certain amount of the reaction liquid from the rear of the inner tank, filter it with a filter, and start circulating the treated liquid back to the front of the inner tank.

Thereafter, a 0.5 mol/l boric acid aqueous solution was continuously dropped into the rear part of the inner tank and maintained for 10 hours. In this state, the reaction solution became a treatment solution having an appropriate degree of silicon dioxide supersaturation.

Here, the absolute removal rate of the filter was adjusted to 1.5 μm and the processing liquid circulation rate was adjusted to 240 mf/min (since the total amount of processing liquid was about 3 liters, the circulation rate was 8%/min). immersed vertically in the middle of the inner tank,
The above conditions (0.2 ml of 0.5 mol/l boric acid aqueous solution
1 min, circulated at 8%/min, and filtered through a 1.5 μm filter) for 3 hours. The thickness of the obtained silicon dioxide coating layer was approximately 900 mm.

In addition, a transparent substrate made of polycarbonate resin (diameter 1
30 mm, thickness 1.2 mm), a dielectric layer (SiA
jl! ON)/recording layer (TbFeCO)/protective layer (Si
A/! ON) were laminated in this order by sputtering to form a magneto-optical recording layer, and then the silicon dioxide film was applied on top of the magneto-optical recording layer via an adhesive layer (acrylic hot melt, film thickness: 60 μm). The coated synthetic resin substrates were bonded together to create a magneto-optical recording medium.

The obtained magneto-optical recording medium is installed in a magneto-optical disk drive using a 780 nm semiconductor laser as a light source,
The optimum value of laser light output during recording was measured. Here, the optimum value of the laser light output during recording is the carrier wave (C)
is the output of the laser beam when the second harmonic (CZ, d) is maximum. In addition, a durability test was also conducted. The results are shown in Table 1.

Example 2 A magneto-optical recording medium was obtained in the same manner as in Example 1, except that the synthetic resin substrate was not subjected to primer treatment, and evaluated in the same manner.

Comparative Example 1 Al (film thickness 0) was used as a metal substrate instead of a synthetic resin substrate.
．． 5 mm), a magneto-optical recording medium was obtained in the same manner as in Example 1, and evaluated in the same manner.

Comparative Example 2 A magneto-optical recording medium was obtained in the same manner as in Example 1, except that a synthetic resin substrate was not used, and evaluated in the same manner.

(The following is the margin) Table 1 [Note: The initial value of C/N is O. **The initial value of the warp was O, and the warp in the direction in which the recording layer side became convex was + (plus).

As is clear from Table 1, the optical information recording medium of the present invention includes:
It exhibited excellent durability, and its durability was comparable to that of a case in which a metal substrate was used as an auxiliary substrate.

In addition to vinyltris(penzoylveroxy)silane used in this example, for example, trimethoxy(vinyl)silane
A synthetic resin substrate that has been plasma polymerized with silane in a glass bell jar with argon gas introduced, a synthetic resin substrate that has been coated with an isobutanol solution of monoethanolamine and dried, and a synthetic resin that has been immersed in an isoprobil solution of monochrome acetic acid. When a magneto-optical recording medium similar to that of this example was used for the substrate, etc., and the same evaluation was carried out, almost the same results as in this example were obtained.

[Effects of the Invention] As explained above, according to the present invention, since a synthetic resin substrate whose surface is coated with a silicon dioxide film is used as an auxiliary substrate, there is little change in shape, strong impact resistance, and long-term stability. It is possible to provide a magneto-optical recording medium that is excellent in weight, lightweight, and capable of recording and reproducing information using a low-power laser beam.

Claims (2)

[Claims] (1) A magneto-optical recording medium having at least a transparent substrate, one or more magneto-optical recording layers formed on the transparent substrate, and a synthetic resin substrate provided on the magneto-optical recording layer, . A magneto-optical recording medium, characterized in that a silicon dioxide film is formed on the surface of the synthetic resin substrate. (2) The synthetic resin substrate is immersed in a supersaturated hydrofluorosilicic acid solution of silicon dioxide to deposit a silicon dioxide film on the entire surface of the synthetic resin substrate. A method for manufacturing a magneto-optical recording medium.