JPH04117643A - Both-side recording type magneto-optical recording medium - Google Patents

Abstract

PURPOSE:To improve oxidation resistance and the recording characteristics after long-term use by adhering 1st and 2nd magneto-optical recording media having specific film constitution and film compsn. in such a manner that the metallic films of both face each other, thereby forming the above-mentioned recording medium. CONSTITUTION:The 1st and 2nd magneto-optical recording media A, B constituted by laminating respectively 1st protective films 2a, 2b, magneto-optical recording films 3a, 3b, 2nd protective films 4a, 4b, and metallic films 5a, 5b in this order on substrates 1a, 1b are so laminated that the metallic films 5a, 5b face each other via an adhesive layer 6. The 1st protective films 2a, 2b and the 2nd protective films 4a, 4b consist of SiNn. The magneto-optical recording films 3a, 3b are formed of the amorphous alloy thin films which are formed of 3d transition metals, corrosion resistant metals, and rare earth elements, contain 5 to 30atomic% corrosion resistant metals and have the axis of easy magnetization perpendicular to the film plane. The metallic films 5a, 5b are formed of an aluminum alloy. The oxidation resistance is improved in this way and the degradation in recording characteristics is prevented in spite of long-term use.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a double-sided recording type magneto-optical recording medium that has excellent oxidation resistance and magneto-optical recording properties as well as excellent mechanical properties. It has excellent oxidation resistance, a wide recording power margin, low linear velocity dependence of recording sensitivity, and excellent magneto-optical recording characteristics such as a high C/N ratio. The present invention relates to a double-sided recording type magneto-optical recording medium that has excellent adhesion to a laminated body, is free from warping, and has excellent mechanical properties.

idantachikodamajo 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 in a direction perpendicular to the film surface, and a film surface that is entirely magnetized in one direction is opposite to this direction of magnetization. It is known that it is possible to form magnetic domains with small orientation reversals.゛Indicate the presence or absence of this inverted magnetic domain as ``1'', ``
By making it correspond to "0", it becomes possible to record digital No. 48 on a magneto-optical recording film such as "2".

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

Various attempts have been made to add a third metal to a magneto-optical recording film such as Tb--Fe or Tb--Co in order to improve the oxidation resistance of the thin film.

In a magneto-optical recording medium in which such a magneto-optical recording film is laminated on a substrate, it is desired that the adhesion between the substrate and the magneto-optical recording I-biased J body be excellent.

In addition, magneto-optical recording media, which are made by laminating such magneto-optical recording films on a substrate, do not have sufficient oxidation resistance, and improvements in recording sensitivity are also desired. When writing, it is desired that the recording power margin be wide and that the dependence of the recording power on the linear velocity be small. Here, a wide recording power merge when combining information means that the magneto-optical recording medium has J fHi
When writing, it means that information can be accurately written to the magneto-optical recording characteristics even if the power of the laser beam as the combination light changes slightly, and the linear velocity dependence of the recording power is small. When writing information on a magneto-optical 5J medium using a laser beam, etc., it is important to know how the optimum recording power of the laser beam as the writing light changes between the inner and outer circumferences of the recording medium. It means the worst.

In this way, the light has excellent adhesion to the substrate, has good oxidation resistance, has a high C/N ratio, has a wide recording power margin, has low linear velocity dependence of recording sensitivity, and is free from warping. It is hoped that magnetic distribution ≦ immersion medium will emerge.

The inventors of the present invention have made extensive studies in light of such prior art, and have found that a specific first protection layer, a specific magneto-optical recording film, a specific second protection film, and a specific metal are provided on the substrate. By laminating a magneto-optical recording medium formed by laminating films in this order with a similar magneto-optical recording medium via an adhesive layer, it has excellent oxidation resistance and magneto-optical recording properties and is free from warping. 8! It was discovered that a double-sided recording type magneto-optical recording medium with excellent mechanical properties could be obtained, and the present invention was completed.The present invention has excellent oxidation resistance and a wide recording power margin. , And! l! 12. It has excellent magneto-optical recording properties such as low linear velocity dependence of recording sensitivity and high C/N ratio, and 5. Excellent adhesion between the substrate and the recording layer laminate. The object of the present invention is to provide a double-sided recording type magneto-optical recording medium with excellent mechanical properties.

The first protection is on the board (1a)! (2a) and magneto-optical recording film (
3a), a second protective film (4a), and a metal film (5a), which are laminated in this order. (2b), a magneto-optical recording film (3b), a @2 protective film (4b) and a metal film (5b) are laminated in this order, and the force C1 of the first magneto-optical recording medium. The metal film (5a) and the metal film (5b) of the second magneto-optical recording medium are stacked so as to face each other with an adhesive layer interposed therebetween, and the first protection M (2a),
(2b) and second protection M (4a), (4b) force',
SiNX is formed, and magneto-optical recording films (3a) and (3b
) is at least i selected from (i) 3d transition metals.
(ii) a corrosion-resistant metal, and (iii) at least one element selected from rare earth elements, and the content of the corrosion-resistant metal is 5 to 30 at%. Made of an amorphous alloy thin film with an easy axis of magnetization, gold J
jEM (5a) and (5b) 5f are characterized by being made of aluminum alloy.

The double-sided recording type magneto-optical recording medium according to the present invention has excellent oxidation resistance and a long life because the recording film laminate has a "double" configuration and structure. The recording characteristics do not deteriorate even after long periods of use, and the C/N ratio is high.
In addition, the recording power margin is wide, the linear velocity dependence of recording sensitivity is small, and there is no warping and the mechanical properties are excellent.

The double-sided recording type magneto-optical recording medium according to the present invention will be specifically described below.

The double-sided recording type magneto-optical recording medium 10 of the present invention has a first protective film (2a) on a substrate (1a), as shown in FIG.
), a magneto-optical recording medium (3a), a second protection M (4a), and a gold JE film (5a), which are laminated in this order, and a 1 protective film (2b
), a magneto-optical recording film (3b), a second protective film (4b), and a metal film (5b) are laminated in this order. 5a) and the second
It has a structure in which the metal film (5b) of the optical recording medium is stacked so as to face each other with an adhesive layer interposed therebetween.

In the double-sided recording type magneto-optical recording medium 10 according to the present invention, the substrates (1a) and (1b) may be made of the same material or may be made of different materials. In addition, protective films (2a), (4a), (2b) and (4b
) may be the same or different as long as they are formed from materials as described below. Furthermore, magneto-optical recording films (3a) and (3b) and metal films (5a) and (5b)
) may be the same or different.

The substrate, the protective IL, the magneto-optical recording 11L, the metal film, and the adhesive layer will be described below in sequence.

Envy--1 In the present invention, the material for forming the substrates (1a) and (lb) is not limited to a specific material, but it is preferably formed from a transparent material. In addition to inorganic materials such as glass and aluminum, poly(methyl methacrylate), polycarbonate, polymer alloys of polycarbonate and polystyrene, such as cyclic olefin-based random copolymers as shown in U.S. Pat. No. 4,614,778 Cyclic olefin random copolymerization book as disclosed in the specification Poly-4-methyl-
Examples include transparent organic materials such as 1-pentene, epoxy resin, polyethersulfone, polysulfone, and polyetherimide. Among these organic materials, poly(
Methyl methacrylate), polycarbonate, the cyclic olefin random copolymer disclosed in US Pat. No. 4,614,778, and the following cyclic olefin random copolymers are preferred.

Substrate (1a) of the same-sided recording type magneto-optical recording medium according to the present invention
And (1b) is a copolymer of ethylene and a cyclic olefin represented by the following formula [+] or [I'], which has an intrinsic viscosity [1] of 0 when measured in decalin at 135°C. .05~1oam/
A cyclic olefin random copolymer within the range of g is preferably used. In particular, in the present invention, the softening temperature (TMA) of the above-mentioned cyclic olefin random copolymer is
) is 70° C. or higher (hereinafter referred to as cyclic olefin random copolymer [A]) is preferably used. If desired, a copolymer of ethylene and a cyclic olefin represented by the following formula [r] or [I゛] may be added to the cyclic olefin random copolymer [A] in decalin at 135°C. A cyclic olefin random copolymer (hereinafter referred to as cyclic olefin random copolymer [B]) whose measured intrinsic viscosity [η] is in the range of 0.05 to 5a11/g and whose softening temperature (TMA) is less than 70°C. It is particularly preferable to include the following.

... [1] (where n is 0 or 1, m is 0 or a positive integer, q is 0 or I, and R1-R111 and R-, R' are each independently represents an atom or group selected from the group consisting of a hydrogen atom, a halogen atom, and a hydrocarbon group, and RIs-R+- may be bonded to each other to form a monocyclic or polycyclic ring; Alternatively, the polycyclic ring may have a double bond, and RIs and R" or R17 and R1. may form an alkylidene group).

... [1'] (In the formula [I°], p is O or an integer of 1 or more, and q
and r is 0. 1 or 2, R1 to RI6 each independently represent an atom or group selected from the group consisting of a hydrogen atom, a halogen atom, an aliphatic hydrocarbon group, an aromatic hydrocarbon group, and an alkoxy group, and R' (or R
6) and Re (or R?) 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 [■], n is 0 or l, preferably O. Moreover, m is O or a positive integer, preferably O-3.

And q is 0 or l.

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

Then, R1-R1・and R- and Rh (formula [
I]) or R1-R (formula [r'co) 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 a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom. In addition, examples of the hydrocarbon group include, independently, an alkyl group having 1 to 6 carbon atoms and a cycloalkyl group having 3 to 6 carbon atoms. Specific examples of the alkyl group include methyl Groups include ethyl group, isopropyl group, isobutyl group, amyl group, and specific examples of cycloalkyl groups include cyclohexyl group, cyclopropyl group, cyclobutyl group, and cyclopentyl group.

In addition, in the above formula [I°], R% (or R6) and R
@ (or R?) may be bonded via an alkylene group having 1 to 3 carbon atoms, or may be bonded directly without any group.

In addition, in the above formula [+], when q is O, the ring represented using q forms a five-membered ring.

Furthermore, in the above formula [I], R16 to R11 may be bonded to each other (together) to form a monocyclic or polycyclic ring, and the monocyclic or polycyclic ring has a double bond. You can. Further, RI6 and R111 or R1ma and RI* 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.

The cyclic olefin represented by the formula [1] or [■゛] can be easily produced by condensing a cyclopentadiene and a corresponding olefin or cyclic olefin by a Diels-Alder reaction. can.

Specifically, the cyclic olefin represented by the above formula [1] or [I゛] may be 1! , (blank space below) Bicyclo[2,2,1]HebI/Ene derivatives such as: Shi ■ ConatonotetracycCff [4,4,0,1'', 17
”] -3-dodecene derivatives; such as hexacyclo[6,6,1,l @, 1”°13
．． Of, 70'''']-]4-heptadecene derivative; octacyclo[8,8,O,I'゛'', 1''7
, f ++, +s11″, +1, OL l,
gIl+? ]-]Pentacyclo[6,6,1,I",0"',0"']4- such as 5-tococene derivatives
hexadecene derivatives; tricyclo[4,4,0,1'' such as tricyclo[4,3,0,1'']-]3-decene derivatives; ""] 3-undecene derivative; Nato's pentacyclo[G, 5.li", 0", 0' 5] 4-pentadecene derivative: Diene compounds such as.

Nato's Pentacyclo [7,4,0,1",1" 2.0' 3] 3-pentadecene derivative: Ql+ ] eicosene derivative 0″1.Of 6 g+! , Il.

0+'9] Pentacyclo[8,4,0,I's, I'' with 5-bentacocene derivatives
", O'1'] -3-hexadecene derivative to butacyclo b-henoei: J
Heneikosene derivative 1B, +6.011.0 blind!・11] Nato's nonacyclo [10,10,1,l'', I'''',
l"", 0"'04", 01ko! t, Q Il, W
6 ] -5-hexadecene derivatives and furthermore, can be mentioned.

(Left below) The cyclic olefin random copolymers [A] and [B], which are copolymers of cyclic olefins and ethylene, contain ethylene and the cyclic olefin as essential components. However, in addition to the two essential 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 a mole less than equimolar to the ethylene component unit in the random copolymer to be produced. - σ-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
Then, the repeating unit (a) derived from ethylene is 40
The repeating unit (b) derived from the cyclic olefin is present in a range of 15 to 60 mol%, preferably 25 to 50 mol%.
The repeating units (a) derived from ethylene and the repeating units (b) derived from the cyclic olefin are randomly arranged substantially linearly. In addition, the ethylene composition and cyclic olefin composition are “
As measured by C-NMR, the fact that this cyclic olefin random copolymer is substantially linear and does not have a gel-like crosslinked structure means that the copolymer completely dissolves in decalin at 135°C. It can be confirmed by

The intrinsic viscosity [r/] of such a cyclic olefin random copolymer [A] measured in decalin at 135°C is:
0.05~10di! / g, preferably 0.08~
It is in the range of 5ag/g.

In addition, the softening temperature (T
MA) is in the range of 70°C or lower, preferably 90 to 250°C, more preferably 100 to 200°C. The softening temperature (TMA) is Thermomec manufactured by DuPont.
Using a hanical analyzer, the thermal deformation behavior of a sheet with a thickness of 1 was measured. 635. In addition, the glass transition temperature (Tg) of the cyclic olefin-based Ran6m copolymer is usually 50230°C, preferably in the range of 70 to 210°C.

Further, the crystallinity of the cyclic olefin random copolymerization product measured by the AJ X-ray diffraction method is in the range of 0 to 10%, preferably 0 to 7%, particularly preferably 0 to 5%.

In the present invention, the softening temperature (TMA) as described above is also 7.
Cyclic olefin random copolymer [A
J is a copolymer of ethylene and a cyclic olefin represented by the above formula ErJ or [r'l, which has an intrinsic viscosity [V] of 0.05 to 5 dQ/ as measured in decalin at 135°C.
It is preferable to form the substrate from a cyclic olefin random copolymer composition [BI] having a softening temperature (TMA) of less than 70° C. and a softening temperature (TMA) of less than 70° C.

A cyclic olefin random copolymer having a softening point (TMA) of less than 70t as described above [BI, the repeating unit (a) derived from ethylene is 60 to 98 mol%,
It is preferably present in a range of 60 to 98 mol%, and the repeating unit (b) derived from the cyclic olefin is 2
-40 mol%, preferably 5 to 40 mol%, and the ethylene-derived reversing unit (a) and the cyclic olefin-derived reversing unit (b) are:
They are randomly arranged in a substantially linear manner. The ethylene composition and cyclic olefin composition were measured by 13C-NMR and μ
The fact that BI is substantially linear and has no gel-like crosslinking structure is confirmed by the complete dissolution of the copolymer in decalin at 135°C.

Such a cyclic olefin random copolymer [intrinsic viscosity measured in BI decalin at 135°C [l is 0]
．． 05-5 fIQ/ gl t, < Ii
o, in the range of 08 to 311 IQ/g.

In addition, cyclic olefin random copolymers [softening temperature (T
MA) is below 70°C, preferably in the range -10 to 60°C, more preferably in the range 10 to 55°C. Furthermore, the glass transition temperature (Tg) of the cyclic olefin random copolymer [BJ is usually -30 to 60°C, preferably -22°C.
It is desirable that the temperature is in the range of 0 to 50°C.

In addition, this cyclic olefin-based lander, copolymer [BI
The crystallinity measured by X-ray diffraction method is 0-10%
, preferably 0 to 7%, especially 9% or 0 to 5%
is within the range of

In the present invention, when a cyclic olefin random copolymer composition is used as the substrate, the weight ratio of the cyclic olefin random copolymer [A]/the cyclic olefin random copolymer [BI] is 10010, 1 to 1. 100/10
, preferably in the range of 10010.3 to 100/7, particularly preferably in the range of 10010.5 to 10015. [B] Acid component By blending the [A] acid component within this range, the adhesion to the protective 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] It has the effect of further improving the effect compared to the case of using only the acid component, and if the above-mentioned cyclic olefin random copolymer composition consisting of a blend of [AJ and [BI] is used as a substrate, the protection used in the present invention can be improved. Its excellent adhesion to the film does not change even after being left under high temperature and high humidity conditions.

Cyclic olefin copolymer [AJ and [BI] constitute the substrate in the present invention,
08, JP 61-120816, JP 61-115912, JP 61-115916
No. 1, JP-A-62-252406, JP-A-62
It can be produced by appropriately selecting conditions according to the method proposed by the applicant in JP-A-252407, JP-A-61-271308, JP-A-61-272216, and the like.

In such a cyclic olefin random copolymer, position (b) derived from the cyclic olefin represented by the above formula [I] or [I'] is represented by the following formula [n] or [i°]. Although it is thought that the repeating unit of the structure shown is formed, some of the structural units (b) may be bonded by ring-opening polymerization, and it is also possible to hydrogenate if necessary. be.

[n] (In formula [n], m, n, q and RI-Rl・
and R=, Rh=11 Notation [Similar to the definition in 11.

[■ °] (In the formula [■°], p, q, r and RI-R
IS has the same definition as in formula [I'] above. ) The substrate of the double-sided recording type magneto-optical recording medium according to the present invention includes:
As mentioned above, in addition to the above-mentioned random copolymers of ethylene and cyclic olefins, cyclic olefin ring-opening polymerization<L ring-opening copolymers obtained by ring-opening of the same or different cyclic olefin monomers or ring-opening copolymers thereof It is also possible to use hydrogenated substances. To explain such cyclic olefin ring-opening polymers, ring-opening copolymers, and hydrogenated products thereof using a cyclic olefin represented by the nII notation [T] as an example, they react as described below. It is thought that it constitutes a ring-opened copolymer and a hydrogenated product thereof.

↓ Ring-opening ↓ Hydrogenation Examples of such polymers include ring-opening coelectrochemical combinations 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 polymerized wood, ring-opening copolymerized QE, these hydrogenated substances, and a cyclic olefin-based random copolymer is modified with an unsaturated carboxylic acid such as maleic anhydride. You can leave it there. Such a modified product can be produced by reacting a cyclic olefin resin as described in 1 with unsaturated carboxylic acids, anhydrides thereof, and derivatives such as alkyl esters of unsaturated carboxylic acids. can. 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 and graft polymerizing it to a desired modification rate, or by preparing a modified product with a high modification rate in advance. However, it can also be produced by subsequently mixing this modified product with an unmodified cyclic olefin resin.

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

Furthermore, in the present invention, when producing the above-described cyclic olefin-based random copolymer, it is preferable that the cyclic olefin random copolymer represented by the above formula [I] or Cyclic olefins other than cyclic olefins can also be polymerized. Examples of such cyclic olefins include cyclobutysdichlorobentene, cyclohexene, 3,4-dimethylcyclohexene, 3-methylcyclohexene, 2-(2-methylbutyl)-1-cyclohexene, 2,
3.3a, 7a-tetrahydro-4,7-methano-I
Examples include H-indene 3a, 5.6.7a-tetrahydro-4,7-methano-IH-indene, and the like. These other cyclic olefins can be used alone or in combination, and are usually used in an amount of 0 to 50 mol%.

In addition to the above acid components [A] and [B], the substrate of the double-sided recording type magneto-optical recording medium of the present invention may contain a rubber component for improving impact strength, a heat-resistant stabilizer, a weather-resistant stabilizer, etc. , antistatic agent, slip agent, antiblocking agent,
Antifogging agents, lubricants, dyes, pigments, natural waxes, synthetic waxes, etc. can be blended, and the blending ratio is appropriately π. For example, specific stabilizers that may be added as optional ingredients include tetrakis[methylene-3(3,5-di-7-butyl-4-hydroxyphenyl)propionate comethane, β-(3,5-di-7-butyl-4-hydroxyphenyl)propionate comethane, Butyl-4-hydroxyphenyl)propionic acid alkyl ester, 2.2
Phenolic antioxidants such as ゛-oxamidobis[ethyl-3(3,5-di-butyl-4-hydroxyphenyl) cobrobionate, fatty acid metal salts such as zinc stearate, calcium stearate, calcium 12-hydroxystearate, glycerin mono Examples include fatty acid esters of polyhydric alcohols such as stearate, glycerin monolaurate, glycerin distearate, pentaerythritol monostearate, pentaerythritol distearate, and pentaerythritol tristearate.

These may be blended alone or in combination; for example, tetrakis[methylene-3(3,
Examples include a combination of 5-di-t-butyl-4-hydroxyphenyl)propionate comethane, zinc stearate, 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. (preferably a polyhydric alcohol fatty acid ester).

Such fatty acid esters of polyhydric alcohols include:
Specifically, glycerin monostearate, glycerin monolaurate, glycerin monomyristate, glycerin monopalmitate, glycerin distearate,
Glycerin fatty acid esters such as glycerin dilaurate, pentaerythritol fatty acid esters such as pentaerythritol monostearate, pentaerythritol monolaurate, pentaerythritol dilaurate, pentaerythritol distearate, and pentaerythritol tristearate are used.

Such a phenolic antioxidant may be used in an amount of 0 to 100% based on the total weight of the acid component [A] and the acid component [B].
10 parts by weight, preferably 0 to 5 parts by weight, more preferably 0
The fatty acid ester of polyhydric alcohol is used in an amount of ~2 parts by weight.The total weight of [A] acid component and [B] acid component is 1
0 to 10 parts by weight, preferably O to 10 parts by weight
You can get m with the amount of 5 shields.

The substrate of the double-sided recording type magneto-optical recording medium of the present invention may contain silica, diatomaceous earth, alumina, titanium oxide, magnesium oxide, pumice powder, pumice balloon, hydroxide, etc., as long as the object of the present invention and transparency are not impaired. Aluminum, magnesium hydroxide, base t1=, magnesium carbonate, dolomite, calcium sulfate, titaniumffl potassium, barium sulfate, calcium sulfite, talc, clay mica, asbestos, glass fiber iL glass flakes, glass peas, calcium silicate, montmorillonite, Bentonite, graphite, aluminum powder, molybdenum sulfide, boron M! Taste Silicon carbide fiber, polyamide fiber,
Fillers such as polypropylene fibers, polyester fibers, and polyamide fibers may also be blended.

In the double-sided recording type magneto-optical recording medium according to the present invention, when a cyclic olefin random copolymer or a cyclic olefin random copolymer composition as described in 1 is used as the substrate, the substrate and the first bond 1! It has excellent adhesion with JJi,
Therefore, the recording film has excellent long-term stability, and oxidation of the recording film is effectively prevented. Therefore, a double-sided recording type optical recording medium in which a recording film is laminated on a substrate made of this cyclic olefin random copolymer has excellent durability and long-term stability. Further, the double-sided recording type optical recording medium according to the present invention is free from warpage and cracks.

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

First protective film (2a), (2b) and second protective film used in the double-sided recording type magneto-optical recording medium 1 according to the present invention! (4
a) and (4b) are formed from a film having a composition represented by SiNX, and examples of SiNXlli include a silicon nitride film or a silicon nitride-containing film.

5iN, the atomic ratio of O<x≦5/
3 It is particularly preferable that 0<χ≦473. Specifically, a silicon nitride 1g film such as 5 i 3 N4 (trisilicon tetranitride) or S such that O<x<4/3 is satisfied.
A mixed film of i3N and Si is particularly preferably used. Such a protective film represented by SiNX has Si, N, or Si, as a target, for example.
A film can be formed by a sputtering method using N and Si. The film can also be formed by sputtering Si in a nitrogen-containing mixed gas such as Ar/N2.

The first protective films (2a), (2
b) and the second protective film (4a), (4b) are usually 1
．． It is preferable to have a refractive index of 8 or more, especially 1.8 to 2.2, and magneto-optical recording films (3a) and (3b) described below.
It functions to protect the magneto-optical recording film from oxidation, or it functions as an enhancement film that improves the recording characteristics of the magneto-optical recording film, or it functions as both.

Further, the first protective film and the second protective film made of SiNX (0x≦473) have particularly excellent crack resistance.

In the present invention, the film thickness of @11 protective film (2a) and (2b) is 400 to 2000, preferably 700 to 1500.
8, and the film thicknesses of the second protective films (4a) and (4b) are:
The number of participants is approximately 50 to 10,000, preferably 50 to 700, and more preferably 100 to 400.

In the present invention, the apparent θk of the magneto-optical recording medium can be increased by setting the thickness of the first protective film within the range described in 1. Also, the apparent θk of the second M-protecting film can be increased to 1! ! By setting the originality within the above range, the magneto-optical recording medium has an excellent C.
This has the advantage that a wide recording power margin can be obtained while maintaining the /N ratio.

The magneto-optical recording films (3a) and (3b) are (i) 3d
At least one element selected from transition metals, (ii) a corrosion-resistant metal, and (i) at least one element selected from rare earths.

(i) 3d transition metals include Fe, Co, T
i, V, CrS Mn, NiS Cu1 Zn, etc. are used, and among these, Fe or CO or both are preferable.

This 3d transition metal is preferably contained in the magneto-optical recording film.
It is present in an amount of up to 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, Zr1 Ta, Nb, etc. Among these, PtS, PdS, Ti is preferred, and pt, Pd, or both are particularly preferred.

This corrosion-resistant metal is contained in the magneto-optical recording film in an amount of 5 to 30 atom%, preferably 5 to 25 atom%, particularly 10 to 25 atom%.
It is present in an amount of atomic %, more preferably 10 to 20 atomic %.

If the content of this corrosion-resistant metal is less than 5 at %, the oxidation resistance of the resulting magneto-optical recording film will not be sufficiently improved;
There is a tendency for the coercive force Hc to change greatly or for the Kerr rotation angle θk to decrease over time. Further, if the content exceeds 30 atomic %, the Curie point of the obtained amorphous alloy thin film tends to be lower than room temperature, which is not preferable. Magneto-optical recording film 1 In addition to the above (i) and (ii), at least one selected from the following group (iii)
It is composed of rare earth elements.

Gd, TbS Dy, Ho, Er, Ta Yb.

Lu, La, Ce, PrS Nd, Pm, Sm.

u Among these, Gd, Tb, Dy1 Ho, Nd, Sm.

Pr is preferably used.

At least one rare earth element selected from the above group (preferably 5 to 5ON, 1,000%, more preferably 8 to 45%, particularly preferably 10 to 40 atomic%) is present in the magneto-optical recording film. It exists in

In the present invention, it is particularly preferable that the magneto-optical recording film 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 3d transition element, with Fe and/or CO being 40 atomic %. 80 atomic% or less, preferably 40W, 1,000% or more7
5N, less than 1,000%, more preferably 40 atomic% or more59
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.

When the amount of Fe and/or CO is in the range of 40 atomic % or more and 80 atomic % or less, a magneto-optical recording film that is convenient for oxidation resistance and has an axis of easy magnetization in the direction perpendicular to the film surface can be obtained. It has the advantage of

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 rises and the Kerr rotation angle (θk) increases.As a result, the recording sensitivity of the magneto-optical recording film is increased by changing 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 [atomic ratio Co is 0 or more and 0.
It is desirable that it be 3 or less, preferably 0 or more and 0.2 or less, more preferably 0.01 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, , T b2. according to the present invention. Fe
The magneto-optical recording film having the composition ssCJ shows no decrease in the C/N ratio even after 100,000 recording and erasing cycles.

(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 PL and/or Pd are 5 to 30 atomic%, preferably 1ON, atomic% in the magnetic recording film
more than 30 atom%, more preferably 10 atom%
and less than 20 atom %, most preferably 11 atom % or more and 19 atom % or less.

If the amount of Pt and/or Pd in the magneto-optical recording film exceeds 5 atomic %, especially exceeding 10 atomic %, this will affect the oxidation resistance of the magneto-optical recording film. 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 +tT b2*F e, Cos (atomic ratio) or P d12T b2@F e@3c O
The magneto-optical recording film used in the present invention having a composition represented by t (atomic ratio) does not change its C/N ratio at all even if it is kept in an environment of 85% relative humidity and 80° C. for 1000 hours. On the other hand, T b2. which does not contain Pt or Pd. F
e.

When a magneto-optical recording film having a composition represented by Co is kept in an environment of 85% relative humidity and 80°C for 1000 hours,
The C/N ratio is greatly reduced.

In addition, by adding Pt and/or Pd to the magneto-optical recording film in an amount within the range described in 1 above, it is possible to record information on the magneto-optical recording film or read information using a small bias magnetic field. A sufficiently high C/N ratio can be obtained. If a sufficiently high C/N ratio can be obtained with a small bias magnetic field,
Since the magnet for generating the bias magnetic field can be reduced in size 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. Furthermore, since a sufficiently large C/N ratio can be obtained with a small bias magnetic field, it becomes easy to design a magnet for magnetic field modulation recording that can be overridden.

(1ii) Rare earth element (RE) The magneto-optical recording film according to the present invention contains a rare earth element (RE).
These rare earth elements include Nd,
Sm, PrS CeS Eu,
Gd, Tb.

Dy or Ho is used.

Among these, NdS Pr, Gd, Tb.

Dy is preferably used, 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.

This rare-earth element is useful for RE/(RE+Fe+C
o) Ratio [W, when the child ratio is represented by X, 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, a small amount of various elements may be added to the magneto-optical recording film to improve the Curie temperature, compensation temperature, coercive force He, and Kerr rotation angle θ, or to reduce costs. These elements can be used in a proportion of, for example, less than 10 W, or 1,000%, based on the total number of atoms constituting the recording film.

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

(1) 3d transition elements other than Fe and Co Specifically, Sc, Ti1 V, CrS Mn.

Ni, CuS, and Zn are used.

Among these, Ti, Ni, Cu1Zn, etc. are preferably used.

(■) 4d transition elements other than Pd, specifically Y, Zr, Nb, Mo5Tc
.

Ru1　Rh, Ag, and Cd are used.

Among these, ZrSNb is preferably used.

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

IrS, Au, and Hg are used.

Among these, Ta is preferably used.

(rv) mB group element Specifically, B, Ag, Ga, In, and TR are used.

Among these, BSA9 and Ga are preferably used.

(v) rvB group element Specifically, C, Si, GeS Sn, and Pb are used.

Among these, SiS Ge, Sn, and Pb are preferably used.

(Vl) VB group element Specifically, N, Pl As, Sb, and Bi are used.

Among these, sb is preferably used.

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

Among these, Te is preferably used.

Magneto-optical recording films with the above composition have an axis of easy magnetization perpendicular to the film surface, and are capable of perpendicular magnetic and magneto-optical recording, often exhibiting a rectangular loop with good Kerr hysteresis, and are also amorphous. It is confirmed by wide-angle x#1 diffraction that the film becomes a quality thin film.

In this specification, a square loop with good Kerr hysteresis means the saturated Kerr rotation angle (θkl), which is the Kerr rotation angle at the maximum external magnetic field, and the residual Kerr rotation angle (θkl), which is the Kerr rotation angle at zero external magnetic field. The ratio θ to 2)
This means that 2/θ is 0.8 or more.

The thickness of this magneto-optical recording film is about 100 to 600, preferably 100 to 400, more preferably 150 to 350.

Metal Film In the first magneto-optical recording medium and the second magneto-optical recording medium constituting the double-sided recording type magneto-optical recording medium 1o according to the present invention, the second protective film is provided on the magneto-optical recording film as described above. Further, on this second protective film, a metal film (5a),
(5b) is provided.

In the present invention, the metal film is made of an aluminum alloy. This aluminum alloy is composed of aluminum and at least one element other than aluminum.

As aluminum alloys that make up such metal films:
Drama: Specifically, the following can be exemplified.

AU-Cr alloy (Cr content 0.1~IOw, %),
AQ-Cu alloy (Cu containing Jir0.1-10 atomic%)
, AQ-Mn alloy (Mn content 0.1 to 10 at%),
Ay-Hf alloy (Hf content 0.1 to 0 at%), A
Q-Nb alloy (Nb content t0.1-10 at%), AQ
-B alloy (B content 0.1 to 10 at%), AQ-Ti
Alloy (Ti content 0.1 to 10 at%), Ag-Ti-
Nb alloy (Ti content 0.1-5%, Nb content 0
．． 1 to 5%), AQ-Ti-Hf alloy (Ti content 0.1 to 5%,
) (f-containing Jit0.1-10 at%), AQ-Cr-
Hf alloy (Cr content 0.1-5%, Hf content o
, i ~ 10 at%), A++-Cr-Ti alloy (Cr content 0.1-57W%, Tj content MO11-10 at%), AQ-Cr-Zr alloy (Cr content O91, -5
yy, child%, Zr-containing MO, 1-10 atom%), Ag
-Ti-Nb alloy (Ti content 0.1-5%, Nb
Ag-Ni alloy (Ni content o, i ~ 10 at%), A
Q-Mg alloy (Mg content 0.1-10 at%), AQ
-Mg-Ti alloy (Mg content 0.1-10i%, T
r content 0.1-10 at%), AQ-Mg-Cr alloy (Mg content 0.1-10 at%, Cr content fco, 1
-10 atomic%), AQ-Mg-Hf alloy (Mg content 0
．． 1 to 10 at%, Hf containing io, x to 10 at%),
AQ-3e alloy (Se content 0.1-10 at%),
AQ-Zr alloy (Zr content 0.1-10 at%), A
Q-Ta alloy (Ta content o, i ~ iox%), A
Q-Ta-Hf alloy (Ta containing if (0,1~10w.

/1-Si alloy (Si content 0.1-10 at%), As+-Ag alloy (Ag content 0.1-10vy, Hf content 0.1-10 at%) ,AQ-P
d alloy (Pd content 0.1 to 10 at%), AQ-P
alloy (PT content 0.1-10 at%).

Among the aluminum alloys constituting these metal films, the following are particularly preferable because they have excellent corrosion resistance.

Aluminum alloy containing 0.1-10 atomic% of hafnium, aluminum alloy containing 0.1-10 atomic% of niobium, 0.5-5% of titanium and 0.5-5% of hafnium.
The content of titanium and hafnium on the gold side is 1 to 5.5.
Aluminum alloy that is atomic %, chromium 0.1-5I!
Aluminum alloy containing 0.1 to 9.5 at% of titanium and 0.1 to 9.5 at.% of titanium, aluminum alloy with a total content of chromium and titanium of 10 at.% or less, 0.1 to 10 at.% of magnesium and 0.1 to 10 at.% of chromium.
The content of magnesium and chromium is 1,000%.
Aluminum alloy with 5 at% or less, chromium 0.1~
5y! , 1,000% and hafnium 0.1 to 9.5 atomic%.Aluminum alloys with a total content of chromium and hafnium of 10 atomic% or less, magnesium 0.1 to 10 atomic% and hafnium 0.1 to 9.5 atomic%.
Contains 10 atomic% The total content of magnesium and hafnium is 157I! Aluminum alloy containing 0.1 to 5 atomic % of chromium and 0.1 to 9.5 atomic % of zirconium, where the total content of chromium and zirconium is IO
Aluminum alloy with W% or less, tantalum 0.1~
10 at% and 0.1 to 10 at% of hafnium.
Aluminum alloy with a total content of tantalum and hafnium of 15 at % or less, containing 0.5 to 5 at % titanium and 0.5 to 5 at % niobium, a total content of titanium and niobium of 1 to 5.5 at % Aluminum alloy with atomic% magnesium, 0.1-10 atomic% and titanium 0.1-10
Contains atomic%.The total content of magnesium and titanium is 1
Hafnium 0.1 to aluminum alloy which is 5 atomic % or less
Contains ~9.5 at% chromium, 0.1 to 5 at% chromium, and 0.1 to 9.5 at% titanium Hafnium to an aluminum alloy in which the total content of hafnium, chromium, and titanium is 10 at% or less 0.1 to 10 atom%, magnesium 0.1 to
Base containing 10 atomic% and titanium 0.1-10w, 1,000%
The total content of hafnium, chromium and magnesium is 1
51J! Aluminum alloy cahafnium 0.1-10 at%, magnesium 0.1-10 at%
Aluminum containing hafnium, magnesium, and chromium with a total content of 15 at % or less, containing 0.1 to 10 at % of hafnium, 0.1 to 10 JJf, and chromium of up to 15 at %. , titanium 0
．． Aluminum alloy containing 1 to 10 W, 0.1 to 10 atomic % of titanium, 0.1 to 10 atomic % of titanium, 0.1 to 10 atomic % of titanium, 0.1 to 10 atomic % of titanium, 0.1 to 10 atomic % of titanium, 0.1 to 10 atomic % of titanium, 0.1 to 10 atomic % of titanium, and 10 atomic % or less of chromium. 1-10
Such gold J7APA can be applied to an aluminum alloy containing 1 atomic % and 10% of chromium, and a total content of titanium, magnesium, and chromium of 15 atomic % or less, for example, on the second protective film.
A film can be formed by a sputtering method or the like using a composite target of the above elements or an alloy target thereof.

In addition, the above metal films may contain one or two of the following metals (elements) in addition to the metals constituting each metal film.
It is also possible to contain more than one species.

Examples of such metals include titanium (Ti),
Chromium (Cr), silicon: 77 (S i), tantalum (
T a ), copper (Cu), tungsten (W), zirconium (Zr), manganese (Mn), magnesium (M
g L vanadium (V), etc. Such other metals are usually contained in an amount of 5 at % or less, preferably 2 at % or less. (However, among the metals (elements) exemplified above, gold a < element X, which is already contained in the metal film, shall not be added in the above amount do. For example, the aluminum alloy constituting the metal film may be the above-mentioned AQ-Ti alloy, Au-T
In the case of an i-Hf alloy or the like, titanium (Ti) among the metals (elements) mentioned above is not further contained in the above amount in the aluminum alloy. ) Film thickness of such metal film 14 100-5000 people, preferably 500-3000 people, more preferably 700-2
It is desirable that the number of participants be around 000 people.

In the present invention, the metal film functions as a good thermal conductor layer, and the presence of this gold J/j4 film prevents the center of the bit recorded on the recording layer from becoming excessively hot due to the recording laser beam. As a result, the dependence of recording power on linear velocity is thought to be reduced.

11 Week 1 In the double-sided recording type magneto-optical recording medium 10 according to the present invention, the first
The metal film 5a of the magneto-optical recording medium and the metal film 5b of the second magneto-optical recording medium are bonded via an adhesive layer 6.

14 polyolefin, such as adhesive layer 6;
EVA, synthetic rubber, polyester, polyamide F'
Although hot-melt adhesives such as resorcinol, cyanoacrylate, epoxy, urethane, and UV-curable acrylate-based adhesives can be used, hot-melt adhesives are preferably used in the present invention.

In the present invention, a polyolefin hot melt adhesive having a softening point of 130° C. or higher, preferably over 140° C., particularly preferably 141° C. or higher is used in the width of the hot melt adhesive. It is preferable.

By using this hot-melt adhesive with a high softening point, even if the double-sided recording type magneto-optical recording medium of the present invention is used for a long period of time under high temperature and high humidity conditions, the bonding of two pieces of the magneto-optical recording medium will remain stable. It has the advantage that no misalignment occurs and deformation such as warping is small.

This hot melt adhesive having a softening point of 130°C or higher includes polyolefin (A) and styrene resin (B
) and tackifier (C) are preferred.

As the polyolefin (A), for example, ethylene/propylene/σ-olefin random copolymer red, ethylene/propylene random copolymer polyisobutylene, etc. are used. Further, the σ-olefin constituting the above-mentioned ethylene/propylene/σ-olefin random copolymer includes C4 to C3° a-olefins, with 1-butene and 4-methyl-1-pentene being particularly preferred. Examples of the styrene resin (B) include polystyrene, styrene/a-methylstyrene, styrene/σ-
Examples include polymers or copolymers containing styrene or styrene derivatives as a constituent, such as methylstyrene/vinyltoluene copolymer, with polystyrene being particularly preferred. In addition, as a tackifier, aromatic petroleum resin (for example, C0 petroleum resin), aliphatic petroleum resin (Cs
petroleum resin) aromatic-aliphatic copolymer petroleum resin (C9C &
Petroleum resins such as copolymer resins) or aliphatic cyclized resins having a weight average molecular weight of 5,000 or less, preferably 50 to 3,000 can be used.
0 or less, especially 500-3000, softening point 80-150℃
Petroleum resin is preferred.

The preferred blending ratio of each component constituting this polyolefin hot melt adhesive is that component (A) is 1 to 60% by weight, particularly 5 to 40% by weight, and component (B) is 1 to 60% by weight.
30% by weight, especially 5 to 20% by weight, and component (C) accounts for 30 to 95% by weight, especially 50 to 90% by weight.

Next, a method for manufacturing a double-sided recording type magneto-optical recording medium according to the present invention will be explained.

First, the substrate temperature is kept at about room temperature, and the first protective trap magneto-optical recording film and the second protective film are deposited in this order by sputtering or electron beam using a composite target, an alloy target having a predetermined composition, or a Si3N target. The film is deposited on this substrate (the substrate may be fixed or rotating) using conventionally known film formation conditions such as vapor deposition, and then a metal film is deposited on this as described above. A first magneto-optical recording medium and a second magneto-optical recording medium are manufactured by depositing in the same manner.

Next, the metal film (5a) of the first magneto-optical recording medium obtained as described above and the metal film (5b) of the second magneto-optical recording medium are bonded and integrated using the adhesive layer 6. do. In the case where a real melt adhesive is used as the adhesive layer, the hot melt adhesive is applied to the metal film of the first and/or second magneto-optical recording medium using, for example, a roll coater or the like.Then, the hot melt adhesive is applied to the metal film of the first and/or second magneto-optical recording medium using a cold press or the like. A method can be adopted in which magneto-optical recording media coated with hot melt adhesive are compressed and bonded together.

In the present invention, in manufacturing the first and second magneto-optical recording media, it is possible to form a magneto-optical recording film on a substrate at room temperature, and to have an axis of easy magnetization perpendicular to the film surface. Therefore, there is no need to perform heat treatment such as annealing after film formation.

Note that the amorphous alloy thin film can also be formed on the substrate while heating the substrate to 50-100°C or cooling it to -50°C, if necessary.

It is also possible to bias the substrate to a negative potential during sputtering. In this way, ions of an inert gas such as argon accelerated by an electric field will strike not only the target material but also the perpendicularly magnetized film being formed, resulting in a perpendicularly magnetized film with excellent properties. There is.

In the double-sided recording type magneto-optical recording medium according to the present invention, such as the one described in ``Moxibustion and Emperor J'' 1, the recording layer stack has a specific VL configuration and film composition (i.e., substrate/first insulating film made of SiNx/specific A first magneto-optical recording medium and a second magneto-optical recording medium having a magneto-optical recording medium (11E/second protective film made of SiNx/metal film made of aluminum alloy) were placed so that their gold A films faced each other. The magneto-optical recording characteristics do not deteriorate even after long-term use, the C/N ratio is high, and the recording power margin is wide. Moreover, the dependence of recording sensitivity on linear velocity is small, and there is no warpage and the mechanical properties are excellent.

[Examples] The present invention will be described below with reference to Examples, but the present invention is not limited to these Examples.

In addition, in this specification, the optimum recording power is f =
It represents the recording power at which the second harmonic of the reproduced signal is minimum for a combined signal of I MHz and duty of 50%, and the smaller the difference in the optimum recording power depending on the linear velocity, the smaller the linear velocity dependence.

In the following examples, the compositions of the magneto-optical recording film and the gold s film are in atomic %.

A non-grade copolymer obtained by copolymerizing [abbreviated as DMON] [ethylene content measured by 13C-NMR analysis 59 mol%, DMON content 41 mol%, extreme viscosity measured in decalin at 135 ° C. [7] is o, 42aa /
g Softening temperature (TMA) 154°C On a substrate consisting of 154°C, s+ and NJJ as the first protective Wi film were deposited to a thickness of 1000 by sputtering using Sj, N and targets. On I 3 NaM'A, P
*T1) 2oF essC04JjJ was deposited to a film thickness of 270A.

Furthermore, this P t, T b2. On the FessCot pattern, a Si, Na film was deposited as a second protective film to a thickness of 160 mm by sputtering using a 5i3Nt target, and then A9-Cr-Hf was deposited on the 5i3Na film. A11 by sputtering method using a composite target
A magneto-optical disk was prepared by depositing SACR 2Hf tm to a film thickness of 1800 mm.Next, a roll coater was used to coat the metal layer of the two thus obtained magneto-optical disks. Softening point 145
℃ hot melt adhesive (composition: 21% by weight of ethylene-propylene-1-butene terpolymer, TgllO℃,
Apply 10% by weight of polystyrene with an MFR of 25g/10 minutes and a petroleum resin with a number average molecular i of 1500 (69 heavy weights).
Next, the two magneto-optical recording media coated with a thin film of this hot-melt adhesive were bonded together using a room temperature press machine so that the metal layers faced each other to obtain a double-sided recording type magneto-optical recording medium.

Furthermore, the characteristics of the double-sided recording type magneto-optical recording medium obtained in this way were measured as follows: optimum recording power: recording frequency I MHz, duty ratio (duty
(ratio) 50%, and measurements were made at linear velocities of 5.7 m/s and 11.3 m/s at a reproduction laser power of 1 mW.

Power Margin 2 C/N (dB): Recording frequency 3.7 MHz, d
Uty ratio 33.3%, reproduction laser power 1.0mW
Binding t4 ΔC/N (dB): A life test was performed by leaving the magneto-optical recording medium in an atmosphere of 80°C and 85% relative humidity for 1000 hours, and the C/N ratio was again measured for this magneto-optical recording medium. ΔC/N = (C/N ratio after life test) - (C/N ratio before life test) calculated from the following formula. Also, the adhesion between the substrate and the first protective film (enhancement film) is
Adhesion test evaluated as follows [baseline test (JIS K5400)]
: Recording of sample IIλ On the enhancement film, 11 orthogonal parallel lines are drawn at 1 mm intervals using a cutter knife. Make cuts in the shape of base so that 100 squares are formed in 1 cs 2.

Peel off using cellophane tape (manufactured by Chiban) for evaluation.

Further, after the life test, the warpage of the magneto-optical recording medium was observed and the results are shown in Table 1.

In Example 1, the composition of the first protective film, the magneto-optical recording film, and j'! JW-, 2nd protection II! Membrane Membrane Gold x
The results for t are shown in Table 1 in the same manner as in Example I except that the composition of i was changed as shown in Table 1.

[Brief explanation of drawings]

FIG. 1 is a schematic cross-sectional view of a magneto-optical recording medium according to the present invention. a 2 a. 3 a. 4 a. a b... Substrate b... First protective film b... Magneto-optical recording film b... Second protective film b... Metal film 6... Adhesive layer 0... Double-sided recording type magneto-optical recording medium A...・First magneto-optical recording medium B...Second magneto-optical recording medium

Claims (4)

[Claims] (1) A first light beam formed by laminating a first protective film (2a), a magneto-optical recording film (3a), a second protective film (4a), and a metal film (5a) in this order on a substrate (1a). A magnetic recording medium, a first protective film (2b) and a magneto-optical recording film (on a substrate (1b));
3b), a second protective film (4b), and a metal film (5b) are laminated in this order. The metal film (5b) of the magnetic recording medium is joined to face each other via an adhesive layer, and the first protective film (2a), (2b) and the second protective film (4a)
), (4b) are made of SiN_X, and the magneto-optical recording film (
3a) and (3b) are (i) at least one selected from 3d transition metals, (ii) a corrosion-resistant metal, and (i)
ii) consisting of an amorphous alloy thin film having an axis of easy magnetization perpendicular to the film surface, the content of the corrosion-resistant metal being 5 to 30 atomic %, comprising at least one element selected from rare earths; A double-sided recording type magneto-optical recording medium characterized in that the metal films (5a) and (5b) are made of an aluminum alloy. (2) The substrate (1a) and the substrate (1b) are copolymers of ethylene and a cyclic olefin represented by the following formula [I] or [I'], and the intrinsic viscosity measured in decalin at 135°C The double-sided magneto-optical recording according to claim 1, which is made of a cyclic olefin random copolymer having [η] in the range of 0.05 to 10 dl/g and a softening temperature (TMA) of 70° C. or higher. Medium. ▲There are mathematical formulas, chemical formulas, tables, etc.▼ ...[I] (In the formula, n is 0 or 1, m is 0 or a positive integer, q is 0 or 1, and R^1 ~R^1^8
and R^a, R^b are each independently a hydrogen atom,
Represents an atom or group selected from the group consisting of a halogen atom and a hydrocarbon group, and R^1^5 to R^1^8 may be bonded to each other to form a monocyclic or polycyclic ring, and A monocyclic ring or a polycyclic ring may have a double bond, and R^1^5 and R^1^6, or R^1^7
and R^1^8 may form an alkylidene group). ▲There are mathematical formulas, chemical formulas, tables, etc.▼ ... [I ′] (In the formula [I ′], p is an integer of 0 or 1 or more,
q and are 0, 1 or 2, and R^1 to R^1
^5 each independently represents an atom or group selected from the group consisting of a hydrogen atom, a halogen atom, an aliphatic hydrocarbon group, an aromatic hydrocarbon group, and an alkoxy group, and R^5 (
Alternatively, R^6) and R^8 (or R^7) may be bonded via an alkylene group having 1 to 3 carbon atoms, or may be bonded directly without any group. good. ) (3) A first light beam formed by laminating a first protective film (2a), a magneto-optical recording film (3a), a second protective film (4a), and a metal film (5a) in this order on a substrate (1a). A magnetic recording medium, a first protective film (2b) and a magneto-optical recording film (on a substrate (1b));
3b), a second protective film (4b), and a metal film (5b) are laminated in this order. The metal film (5b) of the magnetic recording medium is laminated so as to face each other with an adhesive layer in between, and the substrate (1a) and the substrate (1b) are made of ethylene and the following formula [I] or [I']. A copolymer with the cyclic olefin shown below, which has an intrinsic viscosity [η] of 0.05 to 10 dl/g as measured in decalin at 135°C.
A copolymer of a cyclic olefin random copolymer [A] which is in the range of A cyclic olefin-based random copolymer [eta] having an intrinsic viscosity [η] measured in decalin at 135°C in the range of 0.05 to 5 dl/g and a softening temperature (TMA) of less than 70°C. B], the first protective film (2a), (2b) and the second protective film (4a)
), (4b) are made of SiN_X, and the magneto-optical recording film (
3a) and (3b) are (i) at least one selected from 3d transition metals, (ii) a corrosion-resistant metal, and (i)
ii) consisting of an amorphous alloy thin film having an axis of easy magnetization perpendicular to the film surface, the content of the corrosion-resistant metal being 5 to 30 atomic %, comprising at least one element selected from rare earths; Double-sided recording type magneto-optical recording medium characterized in that the metal films (5a) and (5b) are made of aluminum alloy; 0 or 1, m is 0 or a positive integer, q is 0 or 1, and R^1 to R^1^8
and R^a, R^b are each independently a hydrogen atom,
Represents an atom or group selected from the group consisting of a halogen atom and a hydrocarbon group, and R^1^5 to R^1^8 may be bonded to each other to form a monocyclic or polycyclic ring, and A monocyclic ring or a polycyclic ring may have a double bond, and R^1^5 and R^1^6, or R^1^7
and R^1^8 may form an alkylidene group). ▲There are mathematical formulas, chemical formulas, tables, etc.▼ ... [I ′] (In the formula [I ′], p is an integer of 0 or 1 or more,
q and r are 0, 1 or 2, R^1~R^1
^5 each independently represents an atom or group selected from the group consisting of a hydrogen atom, a halogen atom, an aliphatic hydrocarbon group, an aromatic hydrocarbon group, and an alkoxy group, and R^5 (
Alternatively, R^6) and R^9 (or R^7) may be bonded via an alkylene group having 1 to 3 carbon atoms, or may be bonded directly without any group. good. ) (4) The cyclic olefin random copolymer composition comprises the cyclic olefin random copolymer [A] and the cyclic olefin random copolymer [B], [A]/
[B] The double-sided recording according to claim 3, which is a cyclic olefin random copolymer composition blended in a weight ratio of 100/0.1 to 100/10. type magneto-optical recording medium.