JPS6278753A - Magnetooptic storage medium - Google Patents

Abstract

PURPOSE:To obtain a magnetooptic recording medium of which the magnetooptic characteristic at and under a high temp. and high humidity is less deteriorated with lapse of time by providing plasma-polymerized layers on the lower or upper side or both sides of a magnetooptic recording layer. CONSTITUTION:The magnetooptic recording layer is a thin film recording layer consisting of an amorphous ferrimagnetic material constituted by combining rare earth and transition metals or crystalline magnetic material such as MnBi or MnBicu. A substrate or article 6 formed with the magntooptic recording layer on the substrate is installed on a base 7 between plate electrodes 3 and 3 and while the inside of a vacuum vessel 2 is evacuated by a vacuum pump 1, a gaseous monomer is introduced through a gaseous monomer supply pie 5 into the vessel 2. Electric power is supplied from an AC power source 4 to the electrodes 3, 3 to induce plasma by the discharge between the electrodes 3 and 3, by which the protective film formed by the gaseous monomer is formed on the surface.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a magneto-optical storage medium used in a magneto-optic recording device that performs at least one of recording, reproducing, and erasing information using light. In particular, it relates to a magneto-optical storage medium with excellent storage stability.

[Prior art]

In recent years, methods for optically recording, reproducing, and erasing information on magnetic thin films using He-Ne lasers, Ar lasers, semiconductor lasers, etc., that is, magneto-optical recording methods, have improved density ratios and access. It has attracted attention as a method capable of increasing speed, and research and development is being intensively promoted in industry.

Magneto-optical recording generally focuses a laser beam onto a thin-film recording medium, lowers the coercive force of the recording medium by locally raising the temperature, and then absorbs the magnetic field from the surrounding stray magnetic field or from the outside. All information is written and erased using an auxiliary magnetic field.

Magnetic recording optical media are typically made of glass, polycarbonate,
Sm, Eu %G d , T on a substrate of epoxy resin, polymethyl methacrylate, polyacrylonitrile
Rare earths such as b s D y s Hp s E r and F
Amorphous ferrimagnetic material or Vi made by combining transition metals such as e, Ni, and Co in various mixing ratios.
, MnB1. A thin film recording layer made of a crystalline magnetic material such as MnB1Cu is formed by vacuum evaporation, sputtering, or the like.

If the thin film recording layer is completely exposed, there are problems such as being oxidized by oxygen and moisture in the atmosphere, or being deteriorated by dust adhesion or contact with the human body.

Furthermore, even if it is not exposed, it is susceptible to deterioration due to water molecules desorbed from the substrate surface or trace amounts of gas generated from inside the substrate and released from the surface. In addition, in the case of double-sided recording media, which are relatively free of such problems, monomers generated from the adhesive (thermosetting or radiation-curing resin is often used) used to bond four symmetrical recording media together. It is also susceptible to deterioration by reactive low-molecular compounds such as , which poses a major problem. In order to deal with these problems, attempts have been made to provide a protective film such as an ultraviolet curing capture layer on the base and/or surface of the recording layer (
Unexamined Japanese Patent Publication No. 2003-111003 (No. 3).

However, in such conventional attempts, the barrier properties of the protective film against water, low-molecular compounds, and ions are insufficient, and deterioration due to aging under high temperature and high humidity conditions has not yet been completely prevented.

[Problem that the invention seeks to solve]

The present inventors have conducted extensive research in view of the above-mentioned problems, and as a result, have arrived at the present invention. That is, an object of the present invention is to provide a magneto-optical storage medium whose magneto-optical properties are less likely to deteriorate over time under high temperature and high humidity conditions.

[Means for achieving invention]

The present invention is)! i disk and magneto-optical storage medium having a magneto-optic recording layer, characterized in that a plasma polymerized layer is provided below or above the magneto-optic recording layer, or on both sides of the magneto-optic recording layer. Regarding.

Examples of the transparent substrate used in the present invention include glass, polycarbonate, polyacrylonitrile, polymethyl methacrylate, and epoxy resin.

As the magneto-optical recording layer used in the present invention, Sm
, Eu, Gd, Tb, Dy, Ho, Er, etc. and F
A thin film recording layer such as an amorphous ferrimagnetic material or a crystalline magnetic material such as MnB1゜MnB1Cu, which is composed mainly of transition metals such as e, Ni, and Co in various mixing ratios, can be used by full vacuum deposition, sputtering, etc. Examples include those formed by

The thickness of the transparent substrate is 0. The thickness of the magneto-optical recording layer is o, oi - 0.5 μm.

The thickness of the plasma polymerized layer is preferably J-OA-0,.2 μm, more preferably 100:100A. If the thickness is less than jOA, it is not preferable because the barrier property against permeation of low molecular weight compounds is insufficient. Also 0.2μm
Providing the above films requires a long time to form the film, which is not practical.

The compounds (hereinafter referred to as monomers) used for forming the plasma polymerized film according to the present invention include λ00C1t O-'
Any material having a vapor pressure of Torr can be used, but one with a boiling point of 2006C or less is preferable. Particularly preferred examples include the following. Namely, methane, ethane, pronogne, butane, penta/, hexane, octane.

Aliphatic saturated hydrocarbons such as heptane, ethylene, propylene, butene, hexene, butadiene, hexatridine,
Aliphatic unsaturated hydrocarbons such as acetylene, aromatic compounds such as benzene, toluene, m-xylene, 0-xylene, p-xylene, ethylbenzene, styrene, naphthalene, cyclopropane, cyclobutane, cyclononane, cyclohexane, cycloheptane , saturated cyclic hydrocarbons such as cyclooctane, cyclononane, and cyclodecane, and partially saturated cyclic hydrocarbons such as cyclobutene, cyclobentene, cyclohexene, and cycloheptene. In addition, tetrafluoromethane, difluoroethane, chlorotrifluoroethane, tetrafluoroethylene, difluoroethylene, hexafluorobutadiene, metaxylene hexafluoride, do, octafluorocyclobutane, etc.
Hydrocarbons such as chlorinated or chlorinated hydrocarbons are also used. In the case of saturated herocarbon, polymerization is difficult to occur unless the number of hydrogen atoms in the molecule is greater than the number of halogen atoms, but polymerization can be achieved by mixing it with a monomer gas containing a large amount of hydrogen.

Alcohols, ketones, ethers, fatty acids, etc. can also be used.

As the monomer gas, those exemplified above can be used alone or in combination.

Silane compounds can also be used.

Among these, more preferred are ethylene, propylene, silane, hexene, phthalene, aliphatic unsaturated hydrocarbons such as acetylene, benzene,
Aromatic compounds such as toluene, m-xylene, 〇-xylene, p-xylene, ethylbenzene, styrene, naphthalene, cyclopropane, cyclobutane, cyclobutane, cyclohexane, cycloheptane, cyclooctane,
These include saturated cyclic hydrocarbons such as cyclononane and cyclodecane, partially saturated cyclic hydrocarbons such as cyclobutene, cyclopentene, cyclohexene, and cycloheptene, and silane compounds having unsaturated alkyl groups such as dimethyldivinylsilane and diallyldimethylsilane.

More preferably, it is an aliphatic unsaturated hydrocarbon such as ethylene, propylene, butene, hexene, butadiene, hexatriene, acetylene, etc., and is represented by the following general formula.

The plasma polymerized film used in the present invention is formed as follows. That is, plasma is generated using a monomer gas by a method described later, and this plasma is applied to the surface of the recording layer (as described in claim (2), a plasma polymerized film is formed between the substrate and the recording layer). In this case, a plasma polymerized film is formed by acting on the substrate surface.

At this time, in addition to the monomer gas, an inert gas such as argon, neon, krypton, or xenon may be added.

Either an electrodeless discharge type or an electrode discharge type may be used as a plasma polymerization treatment apparatus, and an internal electrode type in which the electrode is inside the polymerization tank and an external bending type in which the electrode is outside the polymerization tank may be used. May be used. Furthermore, a method of introducing monomer gas during the afterglow is also possible. Particularly preferred is an internal electrode type (see Figure 1), which makes it easy to obtain a stable plasma state.
and a method of introducing monomer gas during after-glow.

The oscillation frequency of the plasma is not particularly limited, and any low frequency, high frequency, microwave, etc. can be used.

The electron temperature (Tel is preferably from 1,000 to 70,000 K, more preferably from 1,000 K to 30,000 K, and even more preferably from 1,000 K to 30,000 K. Here, Te is, for example,
It can be measured by the two-probe method using a heated thermal probe, as disclosed in Japanese Patent No. 1-13jj71A. Here, if Te is 70,000 or more, it is difficult to provide a uniform plasma polymerized film without pinholes, and if Te is less than 5,000, the polymerization rate is so low that it is not practical.

When Te is between 100 and 100,000, the adhesion with the magnetic thin film is particularly excellent, and an extremely excellent coating can be applied.

For a 1-oot reaction tank, the gas flow rate is o,/ml to zo.
Omt 7 minutes is preferred.

The pressure of the plasma polymerization system is 1O-3 Torr-/Torr.
A range of r is preferred, more preferably lo-3Tor
r to 10'Torr. If the pressure is higher than this, the plasma polymerized film will be formed in powder form or the inside of the plasma reaction tank will be heavily contaminated; if the pressure is lower than this, it will take a long time to form the polymerization 1, which is not preferable.

The magneto-optical recording medium of the present invention preferably has two media bonded together with the magneto-optic recording layers facing each other via an adhesive layer.

The adhesive used in the present invention is a urethane adhesive (an incyanate-containing compound alone or mixed with a substance having a functional group such as Mi, which easily reacts with incyanate, such as a hydroxyl group, an amino group, or a carboxyl group, to form an adhesive); (those that achieve strong adhesion through heat curing), epoxy adhesives (those that react with epoxy compounds and curing agents such as amines), curable silicone sugar, hot melt adhesives (
For example, ethylene-vinyl acetate resin, etc.), high frequency adhesive (
polyvinyl chloride resin, etc.). Solvent-based adhesive (
For example, synthetic rubber-based or vinyl resin-based polymers dissolved in organic solvents are not preferred because they may not have sufficient storage stability. Similarly, UV-curable adhesives are also not preferred.

Next, the present invention will be fully explained in detail with reference to Examples, but the present invention is not limited thereto.

〔Example〕

FIG. 1 shows an apparatus suitably used for forming a plasma polymerized film of the present invention. In this device, plate-like electrodes 3.3 facing each other are provided in a vacuum vessel λ to which a vacuum pump is connected, and an AC power source is connected thereto, while a single or Multiple seven gas supply pipes! The article 6, which is constructed by connecting all the parts and has, for example, a substrate or a magneto-optical recording layer formed on the substrate, is placed on the table 7 between the plate electrodes 3.3, and the protective film is formed as follows. A magnetic recording medium is formed in T-size.

In other words, ■ While evacuating the inside of the empty container λ using an empty pump, the monomer gas mentioned above (which may contain an inert gas) is introduced into the vacuum container λ via the monomer gas supply pipe j. do.

While the atmosphere in the vacuum container λ is kept constant as described above, power is supplied to the electrodes 3, 3 from an AC power supply, thereby generating plasma by discharge at the electrodes 3, 3. Furthermore, the electron temperature at the location where the substrate for film formation is installed! The monomer gas is applied to the article (e.g., a substrate or a substrate with a magneto-optical recording layer) on which a plasma polymerized film is to be formed on the entire surface of the plasma. Forms a protective film.

The thickness of the formed plasma-polymerized film was determined based on the film formation rate obtained from a model experiment and from the relationship: thickness = film formation rate x polymerization time. therefore,
In order to provide a plasma polymerized film with Nozomi's film thickness, the required polymerization time was determined by dividing the desired film thickness by the known film formation rate. The model experiment referred to here is an experiment to determine the proportionality constant of the polymerization time and the thickness of the formed film (measured by ellipsometry) under each polymerization condition. The film formation rate was determined for a film deposited to a thickness of 0OOA.

TbFeC directly on a polycarbonate disk-shaped transparent substrate or on a substrate coated with various protective films.

Magneto-optical recording layers were formed by t-DC magnetron sputtering, the surfaces of which were coated or not coated with various protective films, and samples A/~1 were bound (see Table 1). Furthermore, these same materials were bonded together using an adhesive to produce a double-sided magneto-optical storage medium.

These were designated as Sample A/j-2 (see Table 2).

〔evaluation〕

5i02, S i with RF magnetron Sunotsuta device
01.4, ZnS was produced. The manufacturing conditions are as follows.

The targets used are 5i02, Sin, ZnS, etc.
The initial vacuum level is reduced to 10 Torr or less, and Ar is added to adjust the vacuum to X1O-3 Torr.

Nowa f'iRproow vines on Suno for 10 minutes, 1
A film thickness of oooh was obtained.

Plasma polymerized films A to E were formed using the apparatus shown in FIG. 1 under the conditions shown in the table below.

5i02.8101. +”- and ZnS protective films were created under the following conditions.Si02.5iO was used as a target.
1 and ZnS gold, the initial vacuum was set to 10 Torr or less, and Ar gas was introduced to adjust the vacuum to /x/OTorr. Sputtered with RF for 70 minutes at 00W, film thickness t
-7OOOA.

The following adhesive composition was used.

a Urethane oligomer + trifunctional incyanate curing agent b Urethane oligomer + cofunctional isocyanate curing agent C epoxy oligomer + triethylenediamine curing agent d Shin-Etsu Kagakuyu RTV-≠1 (curable silicone resin) Characteristic evaluation of each sample! θQCKe r rHc before and after storage for 1 week under 120% RH.

OK, and was determined by reflectance measurement.

The above measurements were performed using a He--No laser with a wavelength of 6321.

〔Effect of the invention〕

The magneto-optical storage medium of the present invention has particularly excellent storage stability under high temperature and high humidity conditions.

[Brief explanation of drawings]

Figure 1 shows plasma polymerization g! of the present invention. FIG. 3 is an explanatory diagram showing an example of the position of a device that can be suitably used to form a . l・・・・・・Vacuum pump λ・・・・・・
・・・Vacuum container 3・・・・・・・Electrode
Hiroshi......AC power supply j...Monomer gas supply pipe jA...Supply o-le 4
B... Rolled Kitriroll S... - Substrate to be coated with plasma polymerized film Patent applicant Fuji Photo Film Co., Ltd. Figure 1

Claims (1)

[Claims] 1) A magneto-optic storage medium having a base and a magneto-optic recording layer, characterized in that a plasma polymerized layer is provided below or above the magneto-optic recording layer, or on both sides. Magneto-optical storage medium. 2) The magneto-optical storage medium according to claim (1), characterized in that the two magneto-optic storage media are bonded together with the magneto-optic recording layer sides facing each other with an adhesive layer interposed therebetween. .