JPH046644A - Magneto-optical recording medium - Google Patents

Abstract

PURPOSE:To obtain the magneto-optical recording medium which has the small dependency of a recording power on a line speed, excellent mechanical characteristics, an excellent recording sensitivity, and a wide margin of the recording power by laminating a protective film, magneto-optical recording film, aluminum alloy film, and nickel alloy film on a substrate. CONSTITUTION:This recording medium is formed by laminating the protective film 2, the magneto-optical recording film 3, the aluminum alloy film 4, and the nickel alloy film 5 on the substrate 1. The more particularly preferable material of the substrate is exemplified by an annular olefin random copolymer and the protective film 2 is particularly preferably an SiNx film. The magneto- optical recording film 3 consists of, for example, one kind of 3d transition metals and one kind of rare earths. Further, the aluminum alloy film 4 contains aluminum and at least one kind of elements exclusive of the aluminum. The nickel alloy film 5 contains the nickel and at least one kind of elements exclusive of the nickel. The excellent mechanical characteristics, the small dependency of the recording power on the line speed, the widened margin of the recording power and the improved oxidation resistance and recording power are obtd. in this way.

Description

[Detailed Description of the Invention] Around the time of the present invention, five strings are installed around the i.Regarding a magneto-optical recording medium having a specific metal film, more specifically, the dependence of recording power on linear velocity is small;
The present invention relates to a magneto-optical recording medium that has excellent mechanical properties such as small warpage, excellent recording sensitivity, and a wide recording power margin.

11 Transition metals such as iron and cobalt, terbium (Tb),
A magneto-optical recording film made of an alloy with a rare earth element such as cadrinium (Gd) has an axis of easy magnetization perpendicular to the film surface, and a film surface that is entirely magnetized in one direction in the opposite direction to this direction of magnetization. It is known that small inverted magnetic domains can be formed. The presence or absence of this inverted magnetic domain is “1”, “0”
”, it becomes possible to record digital signals on the magneto-optical recording film as described above.

As a magneto-optical recording film made of such a transition metal and a rare earth element, for example, Japanese Patent Publication No. 57-20691 discloses a Tb--Fe based magneto-optical recording film containing 15 to 30 ffl% of Tb. Also, a magneto-optical recording film made of Tb-Fe added with a third metal is also used. Furthermore, magneto-optical recording films such as Tb--Co and Tb--Fe--Co are also known.

Various methods have been attempted to add a third metal to such Tb--Fe based, Tb--Co based, etc. magneto-optical recording films in order to improve the oxidation resistance of these thin films.

A magneto-optical recording medium formed by laminating such a magneto-optical recording film on a substrate is desired to have excellent mechanical properties such as small warpage.

In addition, a magneto-optical recording medium formed by laminating such a magneto-optical recording film on a substrate has excellent oxidation resistance and recording sensitivity (C/N ratio).
Furthermore, when writing information on such a magneto-optical recording medium, it is desired that the recording power margin be wide and that the linear velocity dependence of the recording power be small. A wide recording power margin when writing information means that when information is written to a magneto-optical recording medium using a laser beam, etc., even if the power of the laser beam used as the writing light changes slightly, the magneto-optical This means that information can be written on the recording medium, and the linear velocity dependence of the recording power is small. This means that the amount of change in the optimum recording power of the laser beam as the writing light is small.

In this way, it is convenient for small warpage and oxidation resistance, and C/N
There is a desire for the emergence of a magneto-optical recording medium that has a high ratio, a wide recording power margin, and a small dependence of recording power on linear velocity.

The inventors of the present invention have made extensive studies in light of such prior art, and have found that a protective film, a magneto-optical recording film, an aluminum alloy film, and a nickel alloy film are laminated in this order on a substrate. The present invention was based on the discovery that magneto-optical recording media have low warpage, convenient mechanical properties, low linear velocity dependence of recording power, wide recording power margin, and excellent oxidation resistance and recording sensitivity. The present invention has been completed to achieve excellent mechanical properties such as warpage of 74 seconds, widening of the recording power margin, and small linear velocity dependence of recording power, and a high C/N ratio. The objective is to provide a magneto-optical recording medium with high performance.

11. Magneto-optical recording medium 14 according to the present invention On the substrate [2] The magneto-optical recording medium is characterized in that a protective film, a magneto-optical recording film, an aluminum alloy film, and a nickel alloy film are laminated in this order.

The magneto-optical recording medium 1 according to the present invention has convenient mechanical properties such as small warpage, low linear velocity dependence of recording power, wide recording power margin, and excellent oxidation resistance and recording sensitivity. Are better.

EMBODIMENT OF THE INVENTION Below, the magneto-optical recording medium according to the present invention will be specifically explained.

For example, as shown in FIG. 1, the magneto-optical recording medium No. 10 of the present invention has a protective film 2, a magneto-optical recording film 3, an aluminum alloy film 4, and a nickel alloy film 5 in this order. It is formed by laminating layers.

Hereinafter, the substrate 1, the protection WL-2, the magneto-optical recording film 3, the aluminum alloy film 4, and the nickel alloy film 5 will be sequentially explained.

Substrate In the present invention, the material of the substrate 1 is not particularly limited, but when the laser beam is incident from the substrate 1 side (arrow A), a transparent substrate is preferable, and specifically, a transparent substrate is used. In addition to inorganic materials such as polymethyl methacrylate, polycarbonate, and polymer alloys of polycarbonate and polystyrene, U.S. Pat. No. 4.614.77
Cyclic olefin random coelectrical composite as disclosed in No. 8 Cyclic olefin random coelectrical composite as described below Poly4-methyl-1-pentene, epoxy Itj! , polyethersulfone, polysulfone, polyetherimide, and other organic materials can be used. Among these, preferred are IL polymethyl methacrylate, polycarbonate, copolymers as described in US Pat. No. 4,614,778, and cyclic olefin random copolymers described below.

In the present invention, particularly preferred materials for the substrate are ethylene and the following general formula [
Examples include a cyclic olefin random copolymer consisting of a copolymer with a cyclic olefin represented by (2) or [t'l.

General formula [I general formula [E'] (wherein n is 0 or 1, m is O or a positive integer, R1 to RI @ 14 each independently & to hydrogen atom, 710 gene atom and Represents an atom or group selected from the group consisting of hydrocarbon groups. RI S 4 Rl @ l Dai May be combined with each other to form a monocyclic or polycyclic ring, and the monocyclic or polycyclic ring has a double bond. Also, RII and R16, or R17 and Ra8
may form an alkylidene group).

(In the formula [1°], p is an integer of 0 or 1 or more, and q
and r are 0, 1, or 2, and R1 to R116 each independently represent an atom or group from the group consisting of a hydrogen atom, a halogen atom, an aliphatic hydrocarbon group, an aromatic hydrocarbon group, and an alkoxy group; or R6) and R9
(or RT) may be bonded via an alkylene group having 1 to 3 carbon atoms, or may be bonded directly without any group. ) However, in the above formula [r], n is O or l, preferably 0. Moreover, m is 0 or a positive integer, preferably 0 to 3.

In the above formula [I'], p is O or an integer of 1 or more, preferably an integer of 0 to 3.

and R1 to R1l+ (formula [I]), or R1-R
15 (Formula [I']) IL Each independently represents an atom or group selected from the group consisting of a hydrogen atom, a halogen atom, and a hydrocarbon group. Here, examples of the halogen atom include: fl fluorine atom, chlorine atom, bromine atom, and iodine atom.

In addition, examples of the hydrocarbon group include an alkyl group having 1 to 6 carbon atoms and a cycloalkyl group having 3 to 6 carbon atoms, and specific examples of the alkyl group include IL, methyl group, ethyl group, etc. Specific examples of cycloalkyl groups include isopropyl group, isobutyl group, and amyl group, and specific examples of cycloalkyl groups include cyclohexyl group, cyclopropyl group, cyclobutyl group, and cyclopentyl group.

Furthermore, in the above formula [I'], R5 (or R6) and R
e (or RT) may be bonded via an alkylene group having 1 to 3 carbon atoms, or may be bonded directly without any group.

Furthermore, in the above formula [I], R15 to RIB may be bonded to each other (together) to form a monocyclic or polycyclic ring, and the monocyclic or polycyclic ring has a double bond. It's okay. Also, Ra5 and Ra6, or R17 and R
18 may form an alkylidene group. Such an alkylidene group usually includes an alkylidene group having 2 to 4 carbon atoms, and specific examples thereof include ethylidene group, propylidene group, isopropylidene group, and imbutylidene group.

A cyclic olefin represented by the above formula [r] or [I'] can be easily produced by condensing a cyclopentadiene with a corresponding olefin or cyclic olefin by a Diels-Alder reaction. can.

As the cyclic olefin represented by the formula [I] or [r,'], specifically, for example, the following compounds can be used.

(Margin below) hmm Methylbicyclo[2 Bicyclo [2, 2, 11 hept-2- enticement conductor hmm 5.10-dimethyltetra CH.

Hs 9-isobutyl-2,7- 9,11,12-)dimethyl 9-ethyl-11,12-dime 9-isobutyl-11,12 8-methyltetrashif 8-ethyltetrashif 1・]-]3-dodese -hexyltetracycline C1・h8ma 1 @ Co 3 Dodesen 5,8.9.10-tetramethy Illko Dodesen Methyl-9-ethylte 8-chlorotetrashif 3-Dodecene promochitrasif 8-Fluorotetracy I@ko 3-Dodecene +s co 3-Dodecene +s]-3-dodecene hmm 8-ethylidene-9-iso 1e co 3 Dodesen One dodecene -3-dodecene , 12 5.17 11B]-3-dodece hmm +　s　]-]3-dodese N, 17 Meko 3-Dodecene , 12 6.17 1 @ Co 3 - Dodese 8-n-propylidene-9 hmm One dodecene 8-n-propylidene 8-isopropylidene [4,4,0,12 S, 17・l] Dodesen One dodecene eye] 3-Dodecene 1e co-3-dodecene 8-n-propylidene-9 [4,4,0,12 +@]-3 CH.

Tetracyclo[4,4,0,12s,Iv +1]-3-dodecene derivatives such as [4,4,0,12 11-3-dodecene-dodecene; +3. Q2.7 Q Hexacyclo such as 4-heptadecene [6,6,1,13Q2, ?
. 14 7, 11 1, 11 3, +8. Q3 +1. Ql2 Pentacyclo[6,6,1,13・6,027,
09+-]-4- Hexadecene derivatives heptacyclo[8,7,0 Hebutacyclo-5 such as cosene, icosene derivatives or hebutacyclo-5-heneicosene derivatives; tricyclo[
Tricyclo[4,4,0,125-co-3-undecene derivatives such as 4,3,0,1; tricyclo[4,3,0,12-6co such as 5-methyl-tricyclo1.3 dimethyl-penta 3-decene derivative.

1,6-dimethylbentamethyl substituted pentacyclo[4,7,0,12,5. O8 +3. p 12 co-3-pentadecene derivatives; diene compounds such as pentacyclo[6,5,1 6, QIT, Ql13 co-4-cosenpentadecene derivatives 1S co-4-eicosene; hebutacyclo[7,8, 0,13 7,11@7I0 +1.18,112 15co4-eicosene derivative; and further, 21. lI3.211. QIJ, 19.11s, +@]
-5-bentacocene 0H・3.2°. 14.1°1+s, +. 1-
nonacyclo[9,10,1,1') such as 5-bentacocene, 03・I
, Q2, l I, Ql 22+, 112.
2@, Ql4. Examples include l@, lI6.1J -5-/< tanta:7 sen derivatives, and the like.

(Margin below) can be mentioned.

(Left below) Ethylene as above and general formula [1] or [1']
As a copolymer with a cyclic olefin represented by 13
Intrinsic viscosity [η] measured in decalin at 5°C is 0.05
~10a/H, with a softening temperature (TMA) of 70
A cyclic olefin-based random copolymer (hereinafter referred to as cyclic olefin-based random copolymer [A]) having a temperature of at least .degree. C. is preferably used. If desired, a cyclic olefin random copolymer [A] is a copolymer of ethylene and a cyclic olefin represented by the following formula [I or [I], which was measured in decalin at 135°C. The intrinsic viscosity [
η] is in the range of 0.05 to 54Q/g, and the softening temperature (
Cyclic olefin random copolymer (hereinafter referred to as cyclic olefin random copolymer [B
) may be used in combination.

Cyclic olefin random copolymers [A] and [B] which are copolymers of the above-mentioned cyclic olefins and ethylene; ζ which has ethylene and the above-mentioned cyclic olefin as essential components; In addition to the components, other copolymerizable unsaturated monomer components may be contained as necessary within a range that does not impair the object of the present invention. Specifically, the unsaturated monomer which may be optionally copolymerized includes, for example, propylene, 1-butene, 4-methyl in an amount less than equimolar to the ethylene component unit in the random copolymer to be produced. - a-olefins having 3 to 20 carbon atoms such as 1-pentene, 1-hexene, 1-octene, 1-decene, 1-dodecene, 1-tetradecene, 1-hexadecene, 1-octadecene, 1-eicosene, etc. For example,

Cyclic olefin random copolymer [A] as described above
The repeating unit (a) derived from ethylene is present in the range of 40 to 85 mol%, preferably 50 to 75 mol%, and the repeating unit (b) derived from the cyclic olefin is present in the range of 15 to 60 mol%. mole%, preferably 25
The repeating units (a) derived from ethylene and the repeating units (b) derived from the cyclic olefin are present in a range of ˜50 mol %, and are arranged substantially linearly at random. The ethylene composition and cyclic olefin composition were measured by 13C-NMR. This cyclic olefin random copolymer is substantially linear and does not have a gel-like crosslinked structure. This can be confirmed by complete dissolution in decalin.

The intrinsic viscosity of such a cyclic olefin random copolymer [A] measured in decalin at 135°C [l is 0
．． 05~toa/g, preferably 0.08~5
It is in the range of dΩ/g.

In addition, the softening temperature (T
MA) is in the range of 70°C or higher, preferably 90 to 250°C, more preferably 100 to 200°C. The softening temperature (TMA) is Thermomec manufactured by DuPont.
The thermal deformation behavior of a sheet with a thickness of 1 crane was measured using a hanical analyzer. That is, a quartz needle was placed on the sheet, a load of 49 g was applied, and the temperature was raised at a rate of 5°C/min, and the needle was 0.635. The temperature at which the material penetrates is defined as TMA t4 Further, it is desirable that the glass transition temperature (Tg) of the cyclic olefin random copolymer is usually in the range of 50 to 230°C, preferably 70 to 210°C.

Further, the crystallinity of this cyclic olefin random copolymer [A] measured by X-ray diffraction method is 0 to 10%,
The range is preferably from 0 to 7%, particularly preferably from 0 to 5%.

In the present invention, a cyclic olefin random copolymer having a softening temperature (TMA) of 70°C or higher as described above [
A] is a copolymer of ethylene and a cyclic olefin represented by the above formula [1 or [I'], which has an intrinsic viscosity [η] of 0.05 to 5 as measured in decalin at 135°C. aQ
It is preferable to form the substrate from a cyclic olefin random copolymer composition blended with a cyclic olefin random copolymer [B] which is in the /g range and has a softening temperature (TMA) of less than 70°C. .

In the cyclic olefin random copolymer [B] having a softening point (TMA) of less than 70° C., the repeating unit (a) derived from ethylene is 60 to 98 mol%, preferably 60 to 98 mol%. The repeating unit (b) derived from the cyclic olefin is present in a range of mol% from 2 to
40 mol%, preferably in the range of 5 to 40 mol%, repeating unit (a) derived from ethylene and repeating unit (b) derived from the cyclic olefin 14
They are randomly arranged in a substantially linear manner. The ethylene composition and cyclic olefin composition were measured by +3C-NMR. This cyclic olefin random copolymer [B] is substantially linear and does not have a gel-like crosslinked structure. This can be confirmed by complete dissolution in decalin at °C.

The intrinsic viscosity [η] of such a cyclic olefin random copolymer [B] measured in decalin at 135°C is 0.
．． 05~5 (LQ/g, preferably 0.08~
It is in the range of 3 dll/g.

In addition, the softening temperature (T
MA) is in the range of 70°C, preferably -10 to 60°C, more preferably 10 to 55°C. The glass transition temperature (Tg) If of the cyclic olefin random copolymer [B] is usually in the range of -30 to 60°C, preferably in the range of -20 to 50°C.

Further, the crystallinity of this cyclic olefin random copolymer [B] measured by Xls diffraction method is 0 to 10%.
, preferably in the range of 0 to 7%, particularly preferably in the range of 0 to 5%.

In the present invention, when the cyclic olefin random copolymer [A] and [B] are used as the substrate, the weight ratio of 14 the cyclic olefin random copolymer [A]/the cyclic olefin random copolymer [B] is 10010.
1-100/10. Preferably 10010.3-1
00/7, particularly preferably 10010.5 to 1001
A range of 5 is desirable. [B] Acid component By blending the [A] acid component within this range, the adhesion to the reflective film used in the present invention can be maintained under harsh conditions while maintaining the excellent transparency and surface smoothness of the substrate itself. [A] This cyclic olefin random copolymer composition consisting of a blend of [A] and [B] can be used in the present invention if it is used as a substrate. The excellent adhesion with the reflective film has the characteristic that it does not change even after being left at high temperatures and under high temperature conditions.

The above cyclic olefin copolymers [A] and [B] constituting the substrate in the present invention are disclosed in Japanese Patent Application Laid-Open No. 60-16870.
8 revolution JP-A-61-120816 Public Corporation JP-A-6
1-115912 revolves JP-A-61-115916 revolves JP-A-62-252406 revolves JP-A-62-
It can be manufactured by appropriately selecting conditions according to the method proposed by the applicant in JP-A No. 252407, JP-A-61-271308, and JP-A-61-272216.

In such a cyclic olefin random copolymer, the formula [I] or [! The structural unit (b) derived from the cyclic olefin represented by In some cases, b) is bonded by ring-opening polymerization, and it is also possible to hydrogenate if necessary.

[nl (In the formula [nl, melon n and R1-R111 are the above formula [
It is the same as the definition in [I]. ) [n'co (in formula [11'co, I)% Q-r and Rl-R
l 5 is the same as the definition in the above formula [I']. )
As mentioned above, as the substrate of the magneto-optical recording medium according to the present invention, in addition to the above-mentioned random copolymer of ethylene and cyclic olefin, the cyclic copolymer obtained by ring-opening the same or different cyclic olefin monomers Olefin ring opening polymerization
Ring-opened copolymers or hydrogenated products thereof can also be used. Regarding such cyclic olefin ring-opening polymerization ring-opening copolymers and hydrogenated products thereof, the formula [r
] Taking the cyclic olefin represented by the following as an example, it is thought that it reacts as described below to form a ring-opened copolymer and a hydrogenated product thereof.

↓Ring opening ↓Hydrogenation Examples of such polymers include ring-opening copolymers of tetracyclododecene and norbornene and their derivatives, and hydrogenated products thereof.

In addition, in the present invention, a part of the above-mentioned ring-opening polymerization arc, ring-opening copolymer, these hydrogenated substances, and the cyclic olefin random copolymer is modified with an unsaturated carboxylic acid such as maleic anhydride. It's okay. Such a modified product can be produced by reacting the above-mentioned cyclic olefin resin with an unsaturated carboxylic acid, an anhydride thereof, and a derivative such as an alkyl ester of the unsaturated carboxylic acid. In this case, the content of structural units derived from the modifier in the modified cyclic olefin resin is usually 50 to 10 mol%. Such a modified cyclic olefin resin can be produced by blending a modifier with a cyclic olefin resin to achieve a desired modification rate and graft polymerization, or by preparing a modified product with a high modification rate in advance. It can also be produced by subsequently mixing this modified product with an unmodified cyclic olefin resin.

In the present invention, the above-described hydrogenated products, cyclic olefin random copolymers, and modified products thereof can be used alone or in combination.

In addition, in the present invention, when producing the above-mentioned cyclic olefin random copolymer, a compound represented by the above formula [I] or [I'] is used within the range that does not impair the physical properties of the resulting polymer, etc. It is also possible to polymerize cyclic olefins other than the cyclic olefins mentioned above. Examples of such cyclic olefins include cyclobutene, cyclopentene, cyclohexene, 3,4-dimethylcyclohexene, 3-methylcyclohexene, 2-(2-methylbutyl)-1-cyclohexene, 2,
3.3a,7a-tetrahydro-4,7-methano-
Examples include IH-indene, 3a, 5.6.7a-tetrahuman O-4,7-methano-IH-indene, and the like. Such other cyclic olefins can be used alone or in combination, and are usually used in an amount of 0 to 50 mol%.

Further, the substrate of the magneto-optical recording medium according to the present invention has the above-mentioned [A
] and [B] Acid components, etc. Add rubber components to improve impact strength, heat resistant stability, weather resistant stability, etc.
Antistatic ship Slip ship Anti-blocking Qi L Anti-fog ship Purity Dyes, pigments, natural sources, synthetic methods Wax, etc. can be blended, and the blending ratio is appropriate. Specifically, as a stabilizer to be added as an optional component of f1, tetrakis[methylene-3(3,5-di-
t-Butyl-4-hydroxyphenyl)propionate comethane, β-(3,5-di-t-butyl-4-hydroxyphenyl)propion strict alkyl ester, 2.2
Phenolic antioxidant valve L such as '-oxamidobis[ethyl-3(3,5-di-t-butyl-4-hydroxyphenyl) copropionate] Fatty acid metal salts such as zinc stearate, calcium stearate, calcium 12-hydroxystearate, Examples include fatty acid esters of polyhydric alcohols such as glycerin monostearate, glycerin monolaurate, glycerin distearate, pentaerythritol monostearate, pentaerythritol distearate, and pentaerythritol tristearate. These may be blended alone or in combination, such as tetrakis[methylene-3(3°5-di-t-butyl-4-hydroxyphenyl)propionate comethane and zinc stearate]. Examples include combinations with glycerin monostearate and glycerin monostearate.

In the present invention, it is particularly preferable to use a phenolic antioxidant and a fatty acid ester of a polyhydric alcohol in combination. Polyhydric alcohol fatty acid esters are preferred.

Such fatty acid esters of polyhydric alcohols include 6, specifically 11 glycerin monostearate, glycerin monolaurate, glycerin monomyristate,
Glycerin fatty acid esters such as glycerin monopalmitate, glycerin distearate, glycerin dilaurate, pentaerythritol monostearate, pentaerythritol monolaurate, pentaerythritol dilaurate, pentaerythritol distearate,
Fatty acid esters of pentaerythritol such as pentaerythritol tristearate are used.

6 such phenolic antioxidants Total weight of the above [A] acid component and [B] acid component 100! 0 for quantity parts
The fatty acid ester of the polyhydric alcohol is used in an amount of ~10 parts by weight, preferably 0 to 5 parts by weight, and more preferably 0 to 2 parts by weight. 0 to 10 weight clothes, preferably 0 to 10
It is used in an amount of 5 parts by weight.

For the substrate of the magneto-optical recording medium according to the present invention, silica, diatomaceous earth, aluminum nine titanium oxide, magnesium oxide, pumice powder, pumice balloon,
Aluminum hydroxide, magnesium hydroxide, basic magnesium carbonate, dolomite, calcium sulfate, potassium titanate, barium sulfate, calcium sulfite, talc,
Clay mica, asbestos, glass woven rim Glass flakes, glass beads, calcium silicate, montmorillonite, bentonite, graphite, aluminum powder, molybdenum sulfide, boron woven paper Silicon carbide woven rim Polyethylene woven paper Polypropylene woven rim Polyester woven rim Filled with polyamide fibers, etc. Agents may also be added.

In the present invention, when a cyclic olefin-based random copolymer or cyclic olefin-based random copolymer composition as described above is used as a substrate, there are some problems whose reasons are unclear.
It is characterized by particularly excellent recording sensitivity. In addition, the substrate made of this cyclic olefin random copolymer or a composition containing the copolymer and the recording layer laminate have excellent adhesion, so that the recording film has excellent long-term stability and is resistant to oxidation. effectively prevented. Therefore, an optical recording medium comprising a recording film laminated on a substrate made of this cyclic olefin random copolymer has excellent recording sensitivity and is also excellent in durability and long-term stability. Furthermore, the optical recording medium according to the present invention is free from warpage and cracks.

The thickness of such a substrate 1 is not particularly limited, but is preferably 0.5 to 5 mm, particularly preferably 1 to 2 mm.

Protective film 2 used in the magneto-optical recording medium 10 according to the present invention
if, SiN,, Z n S, Z n S e,
CdS.

It is formed from a film having a composition such as Si or ApN, and among these, SiN film is particularly preferable.

In the protective film represented by SiNx, it is preferable that O<x≦473. Specifically, a silicon nitride film such as 5r3NaC trisilicon tetranitride) or Si3N such that 0x<4/3 is used. A mixed film containing Si is particularly preferably used. Such a protective film represented by SiN can be formed by a sputtering method using Si, N, or 5i3Na and Si as targets, for example. The protective film 2 made of SiN preferably has a refractive index of 2.0 or higher, and has the function of protecting the magneto-optical recording film 3 from oxidation, which will be described later, or protecting the magneto-optical recording film from oxidation. It functions as an enhancement film that improves recording characteristics, or both. In addition, the protective film 1 made of S jN (0<x≦4/3) is particularly excellent in crank resistance.

In the present invention, the thickness of the protective film 2 is desirably about 500 to 2000, preferably about 800 to 1 SoO.

In the present invention, by setting the thickness of the protective film within the above range, a magneto-optical recording medium having a good C/N ratio and a wide recording power margin can be obtained.

The optical magnetic recording film 3 consists of (i) at least one element selected from 3D transition metals, and (1ii) at least one element selected from rare earths, or (i) at least one element selected from 3D transition metals.
It consists of at least one element selected from transition metals, (ii) a corrosion-resistant metal, and (1ii) at least one element selected from rare earths.

Among these, (i) at least one selected from 3d transition metals;
A magneto-optical recording film comprising at least one element selected from (11) a corrosion-resistant metal, and (iii) a rare earth element is preferred.

(i) 3d transition metals include Fe, Co, T
i, Vl Cr, Mn, Ni, CuS Zn, etc. are used. Of these, Fe or Co or both are preferred.

This 3d transition metal is preferably contained in the magneto-optical recording film.
It is present in an amount of ~90 atom %, more preferably 30 to 85 atom %, particularly preferably 35 to 80 atom %.

(ii) By including a corrosion-resistant metal in the magneto-optical recording film, the oxidation resistance of the magneto-optical recording film can be improved. Such corrosion-resistant metals include Pt, Pd
, Ti, Zr, Ta, Nb, etc., among which PtSPd and Ti are particularly preferred, and Pt, Pd, or both are particularly preferred.

This corrosion-resistant metal is present in the magneto-optical recording film at 30 atomic % or less, preferably from 5 to 25 atomic %, particularly from 10 to 25 atomic %.
JF, present in an amount of 1,000%, more preferably 10-20 atomic%.

Examples of rare earth elements include the following elements.

GdS Tb, DyS Ho, Er, Tm
, Yb.

Lu La, Ce, Pr, Nd, P
m, Sm.

u Among these, Gd, Tb, Dy, Ho, N
d55m5Pr is preferably used.

At least one rare earth element selected from the above group is present in the magneto-optical recording film in an amount of preferably 5 to 50 atomic %, more preferably 8 to 45 atomic %, particularly preferably 10 to 40 atomic %. ing.

In the present invention, the magneto-optical recording film preferably has a composition as described below.

(i) 3d transition element The magneto-optical recording film according to the present invention preferably contains Fe and/or CO as the jL(i) 3d transition element, and contains 40 at.% of Fe and/or Cot.
80J] K% or less, preferably 40 atomic% or more7
5 atomic % atomic %, more preferably 40 JX atomic % or more 59
It is desirable that it is present in an amount of atomic percent or less.

Furthermore, Fe and/or Co are Co/(Fe+Co
) is present in the magneto-optical recording film in an amount such that the ratio [atomic ratio] is 0 or more and 0.3 or less, preferably 0 or more and 0.2 or less, and more preferably 0.01 or more and 0.2 or less. It is desirable to be present.

80W when the amount of Fe and/or Co is 40 at% or more
When the content is in the range of less than 1%, it has the advantage that a magneto-optical recording film having excellent oxidation resistance and having an axis of easy magnetization perpendicular to the film surface can be obtained.

By the way, when CO is added to the magneto-optical recording film, (a)
It has been observed that the Curie point of the magneto-optical recording film increases and the Kerr rotation angle (θk) increases.As a result, it is possible to adjust the recording sensitivity of the magneto-optical recording film by adjusting the amount of %Co added. Moreover, by adding Co, the carrier level of the reproduced signal can be increased. In the magneto-optical recording film according to the present invention, in terms of noise level and C/N ratio, the Co/(Fe+Co) ratio [ff ratio is 0 or more and 0.3 or less, preferably 0 or more and 0.2 or less, more preferably 0 or more and 0.2 or less. is 0
．． It is desirable that the value is 01 or more and 0.2 or less.

In such a magneto-optical recording film used in the present invention, even if recording and erasing are repeatedly performed, film deterioration does not occur. For example, P t 13T b2@F e according to the present invention
Even after repeated recording and erasing of 100,000 times on the magneto-optical recording film +L having the composition ssCO@, no decrease in the C/N ratio was observed.

(ii) Corrosion-resistant metal The magneto-optical recording film used in the present invention preferably contains Pt, Pd, or both as the (ii) corrosion-resistant metal, and pt and/or Pd are The magnetic recording film contains 5 to 30 atom%, preferably more than 10 atom% and less than 30 atom%, more preferably more than 10 atom% and less than 20 atom%, most preferably 11 atom% to 19 atom%. Preferably present in quantity.

If the amount of PT and/or Pd in the magneto-optical recording film is 5 atomic % or more, especially if it exceeds 10 atomic %, the oxidation resistance of the magneto-optical recording film will be affected. Pitting corrosion will occur even after long-term use. It has the advantage that the C/N ratio does not deteriorate.

For example, P t,, T b2. Fess COs
Alternatively, the magneto-optical recording film according to the present invention having the composition shown as P d12T b2@F essCO7 can be maintained for 1000 hours in an environment of 85% relative humidity and 80°C.
The C/N ratio does not change at all. On the other hand, pt or P
When a magneto-optical recording film having a composition shown as T b25F e, , Co, which does not contain d is kept in an environment of 85% relative humidity and 80° C. for 1000 hours, the C/N ratio decreases significantly.

Furthermore, by adding pt and/or Pd to the magneto-optical recording film in an amount within the above range, it is possible to reduce the /JX small bias magnetic field when recording or reading information from the magneto-optical recording film. A sufficiently high C/N ratio can be obtained. If a sufficiently high C/N ratio is obtained with a small bias-magnetic field,
Since the magnet for generating the bias magnetic field can be made smaller and the heat generated from the magnet can be suppressed, the drive device for an optical disk having a magneto-optical recording film can be simplified. Moreover, since a sufficiently large C/N ratio can be obtained with a small bias magnetic field, it is easy to create a magnet pattern for magnetic field modulation recording that can be overridden.

(1ii) Rare earth element (RE) A rare earth element (RE) is present in the magneto-optical recording film according to the present invention.
The rare earth elements include ij Nd,
5rrL, Pr, Ce; Eu, Gd,
Tb.

Dy or HO is used.

Among these, NdS Pr, Gd, Tb.

DY is preferred, and Tb is particularly preferred.

Further, two or more kinds of rare earth elements may be used in combination, and in this case, it is preferable that Tb is contained in an amount of 50 at % or more of the rare earth elements.

From the point of view of obtaining opto-magnetism with the axis of easy magnetization in the direction perpendicular to the film surface, it is possible to obtain RE/(RE+Fe+C
o) When the ratio [W ratio] is expressed as X, E, 0.15
It is desirable that it be present in the magneto-optical recording film in an amount such that ≦X≦0.45, preferably 0.20≦X≦0.4.

In the present invention, 1) by adding small amounts of various elements to the magneto-optical recording film, the Curie temperature and the compensation temperature ν) are adjusted to the coercive force H.
It is also possible to improve e and Kerr rotation angle θ or to reduce costs. These elements can be used in a proportion of, for example, 10 atomic % of the total number of thicknesses constituting the recording film.

Examples of other elements that can be used in combination include the following elements:

(I) 3d transition elements other than Fe and Co, Sc, Ti, V, Cr,
Mn.

N1, Cu, and Zn are used.

Among these, TiS Ni, Cu, Zn, etc. are preferably used.

(n) 4d transition elements other than Pd Specifically, Y, Zr5Nb, Mo, and Tc.

RuS Rh and AgS Cd are used.

Among these, Zr and Nb are preferably used.

(m) 5d transition elements other than Pt Specifically, Hf, Ta, W, Re,
Os.

Ir, Au, and Hg are used.

Among these, Ta is preferably used.

(rv) mB group elements Specifically, IL, BSAQ, Ga, In, and Tg are used.

Among these, BS Al15 Ga is preferably used.

(v) rvB group elements, specifically If, C, 5iSGe, Sn, P
b is used.

Among these, Si and GeS Sn1 Pb are preferably used.

(Vl) VB group element Specifically, N, PS AsS Sb, and Bi are used.

Among these, sb is preferably used.

(■) VTB group elements Specifically, SS Se, Te, and Po are used.

Among these, Te is preferably used.

A magneto-optical recording film having the above composition has an axis of easy magnetization perpendicular to the film surface, and is often an amorphous thin film that exhibits a rectangular loop with good Kerr hysteresis and is capable of perpendicular magnetic and magneto-optical recording. This force can be confirmed by wide-angle X-ray diffraction.

In this specification, when Kerr hysteresis shows a good rectangular loop, the saturated Kerr rotation angle (θkl) is the Kerr rotation angle at the maximum external magnetic field, and the residual Kerr rotation angle (θkl) is the Kerr rotation angle at zero external magnetic field. The ratio θ to 2)
This means that 2/θ is greater than or equal to 8.

The thickness of this magneto-optical recording film is about 100 to 600, preferably 100 to 400, more preferably 150 to 300.

Aluminum Alloy In the magneto-optical recording medium 10 according to the present invention, an aluminum alloy film 4 is provided on the magneto-optical recording film 3 as described above.

This aluminum alloy film 4 is composed of aluminum and at least one element other than aluminum.

Specific examples of such aluminum alloys include the following:

AQ-Cr alloy (Cr content 0.1-10%)
, A11-Cu alloy (Cu content 0.1 to 10 at%)
, Ag-Mn alloy (Mn content 0.1 to 10 at%),
AQ-Hf alloy (Hf content 0.1~10%)
), AQ-Nb alloy (Nb content 0.1-10 at%)
, AQ-B alloy (B content 0.1-10y!, 1,000%),
AQ-Ti alloy (Ti content 0.1-10 at%)
, AQ-Ti-Nb alloy (Ti content 0.1 to 5 at%
, Nb content 0.1-5M%), AQ-Ti-Hf alloy (Ti content 0.1-5g,%
, Hf content 0.1 to 10 at%), Al1-Cr-H
f alloy (Cr content 0.1-5 at%, Hf content 0.
1-10 atomic%), AQ-Cr-Ti alloy (Cr content 0.1-5%, Ti content 0.1-10W,
1,000%), A9-Cr-Zr alloy (Cr content 0.1-5
atomic%, Zr content 0.1-10W%), Aff −
T1-Nb alloy (Ti content 0.1-5 at%, Nb
AQ-Ni alloy (Ni content 0.1 to 10 at%), AQ-Ni alloy (Ni content 0.1 to 10 at%), A
Q-Mg alloy (Mg content 0.1-10 at%), Ag
-Mg-Ti alloy (Mg content 0.1-10 at%, T
i content 0.1-10 at%), As-Mg-Cr alloy (Mg content 0.1-10 at%, Cr content 0.1-10 at%)
10y! , 1,000%), AQ-Mg-Hf alloy (Mg content 0.1-10 at%, Hf content 0.1-1ON, 1,000%)
), A9-3 e alloy (Se content 0.1-10 at%
), Am-Zr alloy (Zr content 0.1-10 at%)
, Ag-Ta alloy (Ta content 0.1-10J11%), AQ-Ta-Hf alloy (Ta content 0.1-10
atomic%, Hf content 0.1 to 10 atomic%), AN-Si
Alloy (Si content 0.1-10%), AQ-Ag
alloy (Ag content 0.1-10 at%), AQ-Pd alloy (Pd content 0.1-10 at%), A11-Pt alloy (pt content 0.1-10 at%).

In particular, the following aluminum alloys are suitable for
This is preferable because the linear velocity dependence of the magneto-optical recording medium is small and the corrosion resistance is excellent.

Aluminum alloy containing 0.1 to 10 atomic % of hafnium, aluminum alloy containing 0.1 to 10 atomic % of niobium, containing 0.5 to 5 atomic % of titanium and 0.5 to 5 atomic % of hafnium. Aluminum alloy with a total content of 1 to 5.5 at%, chromium 0.1 to 5 at%
Aluminum alloy with a total content of chromium and titanium of 10 at% or less, containing 0.1 to 5 at% chromium and 0.1 to 9.5 at% titanium.
Aluminum alloy with a total content of chromium, titanium, and hafnium of 10 at% or less, magnesium 0.1-10 at% and chromium 0.1-10 at%
Contains atomic% Total content of magnesium and chromium is 1
Aluminum alloy with 5 at% or less, chromium 0.1~
5 atomic% and hafnium 0.1-9.5 atomic% combined
Aluminum alloy with a total content of chromium and hafnium of 10 at % or less, magnesium 0.1 to 10 at % and hafnium 0.1 to 10 at %
10 at% combined Aluminum alloy with a total content of magnesium and hafnium of 15 at% or less, chromium 0.1 to 5 at% and zirconium 0.1 to 9.5 at%
& Aluminum alloy with a total content of chromium and zirconium of 10 at% or less, tantalum 0.1 to 1
0 atom % and 0.1-10 g of hafnium.

The total content of tantalum and hafnium is 1,000%.
Aluminum alloy, titanium 0.5 to 5 atomic % or less
Aluminum alloy with a total content of titanium and niobium of 1 to 5.5 at%, containing 0.1 to 10 at% of magnesium and 0.1 to 10 at% of titanium.
Combined atomic % Aluminum alloy with a total content of magnesium and titanium of 15 atomic % or less, containing 0.1 to 10 atomic % of magnesium and 0.1 to 10 atomic % of titanium, and the total content of magnesium and titanium Aluminum alloy with an amount of 15 atomic % or less, magnesium 0.1 ~
10 at%, hafnium 0.1-10 at% and titanium 0
゜Aluminum alloy containing 1 to 10 atomic % and having a total content of magnesium, hafnium, and titanium of 15 J11 (2%) or less, magnesium 0.1 to 10 atomic %
an aluminum alloy containing 0.1 to 10 atomic % of hafnium and 10 atomic % or less of chromium, and a total content of magnesium, hafnium, and chromium of 15 atomic % or less, magnesium 0.1 to 10 atomic %, and titanium. 0.1~1
Aluminum alloy containing 0 atomic % and 10 atomic % or less of chromium, and the total content of magnesium, titanium, and chromium is 15 atomic % or less, magnesium 0.1 to 10 atomic % and hafnium O2 1 to 10 atomic %.
10g, % and titanium 0.1~10W, % and chromium 1
Aluminum alloy films containing 0 atomic % or less and having a total content of magnesium, 71 hunium, titanium, and chromium of 15 atomic % or less. In addition, one or more of the following metals (elements) may be included. Such metals (for example, titanium (Ti)
, chromium (Cr), silicon (Si), tantalum (Ta
), copper (Cu), tungsten (W), zirconium (
Zr), manganese (Mn), magnesium (Mg), vanadium (V), etc. These other metals are usually contained in an amount of 5i atomic % or less, preferably 2 atomic % or less. (However, among the metals (elements) as exemplified above, the metals (elements) already contained in the aluminum alloy film shall not be added in the above amounts to the aluminum alloy film. For example, if the aluminum alloy constituting the aluminum alloy film has the above-mentioned AQ
-Ti alloy, Ag-Ti-Hf alloy, etc., titanium (TI) among the above-mentioned metals (elements) is not further contained in the above-mentioned amount in the above-mentioned aluminum alloy. ) The film thickness of such an aluminum alloy film 4 is 100 to 5
000 people, preferably 500 to 3000 people, and more preferably about 700 to 2000 people.

This aluminum alloy film 4 functions as a good thermal conductor layer, and the presence of this aluminum alloy film prevents the recording layer from becoming excessively high temperature due to the recording laser beam.As a result, the recording power decreases. It is thought that the dependence on linear velocity becomes smaller.

In addition, the aluminum alloy film of the present invention has excellent corrosion resistance, so even after long-term use, the linear velocity dependence of the recording medium is small by tJ.
It also has an excellent protective effect on the recording layer.

In the magneto-optical recording medium 10 according to the present invention, a nickel alloy film 5 is provided on the aluminum alloy film 4 as described above.

This nickel alloy film 51 is composed of nickel and at least one element other than nickel.

Specifically, the following alloys can be used as such a nickel alloy.

Ni-Cr alloy (e.g. 30-99 atomic% Ni, 1
~70 atom% Cr, particularly preferably 70~95ff
%Ni, 5~30W%Cr) Ni-Si alloy (
For example, 85N, %Ni 110m%Si, 3 atomic%
Cu, 2 atomic% A) Ni-Cu based alloy (e.g. 63 atomic% Ni.

29~30Jli (%Cu, 0.9~2ff%Fe
.

0.1 to 4 atomic% Si, O to 2.75 J]i! child%A)
Ni-Mo-Fe alloy (e.g. 60-65 atomic%N
i, 25-35 atom% MO, 15 atom% Fe) Ni-Mo-Fe-Cr alloy (for example, 55-60 atom% Ni, 15-20 atom% Mo, 6 atom% Fe,
12-16 JPC% Cr, 5 atom% W) Ni-Mo-
Fe-Cr-Cu alloy (e.g. 60 atomic% Ni15
At.%Mo18 At.%Fe.

21 atom% Cr, 3i atom% Cu, 1fJi1. Child%S
i.

1 atomic% Mn, 1 atomic% W1 or 44-47 atomic% Ni, 5.5-7.5 atomic% Mo, 21-23
atomic% Cr, 0.15 atomic% Cu, 1 atomic% Si, 1~
2 atomic % Mn, 2.5 N, child % C011 atomic % W11.
7-2.5ffl%Nb, balance Fe)Ni-C
r-Cu-Mo alloy (e.g. 56-57 atomic% Ni
, 23-24i%Cr, 8yK%Cu, 4[%M
O12yK%W, 1 atomic%Si or Mn) Ni-Cr-Fe alloy (e.g. 79.5N%Ni
113JjC%Cu, 6.5at%Fe.

0.2 atom% Cu, or 30-34 atom% Ni
, 19-22 atomic % Cr, 0.5 J]iE child % Cu, 1
% Si, 1.5 atomic % Mn, balance Fe) Among these, a Ni-Cr alloy film is particularly preferably used.

The film thickness of such a nickel alloy film 5 is +4200~5oo
o people, preferably 300 to 3000 people, more preferably 5 people
It is desirable that the number of participants be about 00 to 2000 people.

The magneto-optical recording medium of the present invention having the nickel alloy film 5 as described above has excellent mechanical properties such as small warpage.

In addition, in the magneto-optical recording medium 10 according to the present invention, the aluminum alloy film 4 and the nickel alloy film 5 as described above are used.
It may have a protective film. As such a protective film, L
A material similar to the protective film 2 described above is used.

An overcoat may be applied on the outermost nickel alloy layer. As an overcoat agent, ultraviolet curing resins, such as acrylic type ultraviolet curing resins, are usually used.
It is coated to a thickness of about 1 to 100 μm. Further, a top coat may be applied on the substrate on the opposite side from the protective film.

Magneto-optical recording medium 1014 according to the present invention Protective film Magneto-optical recording film Aluminum alloy layer Nickel alloy film is formed on the substrate by employing a film-forming method such as vacuum evaporation, sputtering, or electron beam evaporation. It can be manufactured by

The magneto-optical recording medium according to the present invention includes a protective film on a substrate, a magneto-optical recording film, a nickel alloy film such as an aluminum alloy film, and a protective film on the substrate, a magneto-optical recording film, an aluminum alloy layer and a nickel alloy film in this order. It has excellent mechanical properties such as small warpage because it is laminated with
It also has excellent oxidation resistance and recording sensitivity.

[Example] The present invention will be explained below with reference to Examples.The present invention is not limited to these Examples.

A non-quality copolymer (hereinafter abbreviated as DMON) of 13C
- Ethylene content 59 mol% determined by NMR analysis, DM
ON content 41 mol%, intrinsic viscosity measured in decalin at 135°C [l 0.42 dl/g, softening temperature (TMA
) on a substrate consisting of 154°C) and a protective film consisting of Si2N4 with a thickness of 1100 and Pt with a thickness of 300^.

A magneto-optical recording film consisting of Tb2@F essc o2 is sequentially laminated by sputtering, and an aluminum-titanium-hafnium film with a thickness of 2000 mm is deposited on this recording film by sputtering using a composite target of aluminum-titanium-hafnium. The content of titanium in the aluminum alloy (layer) constituting the obtained aluminum alloy layer is 1y! , and the hafnium content was 2 atomic %.Furthermore, on this aluminum alloy layer, a nickel-chromium alloy with a thickness of 500 mm was deposited by sputtering using a nickel-chromium composite target. The resulting nickel alloy (layer) had a nickel content of 90 Jl[%] and a chromium content of 10 atomic%.The resulting magneto-optical recording medium was heated at 70°C. After being kept in an atmosphere with a relative humidity of 85% for about 48 hours, the change in warpage of this magneto-optical recording medium was examined, and no change was observed compared to the substrate (before film formation). Magneto-optical recording media have a linear velocity of 5.7 m/s
The optimum recording power at EC is 4.1 mW, and the optimum recording power at linear velocity of 11 m/sec and 3 m/sec is 6.1 mW.
At 5mW, the power margin is C/N Max-3d
It is the range of recording power that can obtain B or more, and f
=3.7MHz1 duty 33.3%, linear speed=5.
At 7 m/sec, the power margin (Pm) is 3.6 mW, the C/N ratio is 47.7 dB, and in this specification, the optimum recording power is
It refers to the recording power at which the second harmonic of the reproduced signal is minimum for a write signal with a duty of 50%.The smaller the difference in optimal recording power due to linear velocity, the less the linear velocity dependence.

[Brief explanation of drawings]

FIG. 1 is a sectional view of the magneto-optical recording medium of the present invention. 1... Board 3. Magneto-optical recording film 5. Nickel alloy film 0...Magneto-optical recording medium 2. Protective film aluminum alloy membrane Retired Emperor Geji ] figure

Claims (1)

[Claims] (1) A magneto-optical recording medium characterized in that a protective film, a magneto-optical recording film, an aluminum alloy film, and a nickel alloy film are laminated in this order on a substrate.