JPH0349059A - Information recording medium - Google Patents

Abstract

PURPOSE:To obtain the recording medium having excellent corrosion resistance and the small dependency of a recording power on a line speed by forming a metallic layer of an Al alloy having a prescribed compsn. CONSTITUTION:This recording medium has a recording layer 3 and the metallic layer 4 on a substrate 2. The metallic layer 4 consists of an Al alloy contg. at least one kind of the elements selected from Hf and Nb at 0.1 to 10atomic % based on the total atoms constituting the Al alloy. This information recording medium has the metallic layer consisting of the Al alloy contg. at least one kind of the elements selected from the Hf and Nb and, therefore, the recording medium has the excellent corrosion resistance, the small dependency of the recording power on the line speed and the excellent protective effect on the recording layer.

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field of the Invention The present invention relates to an information recording medium having a metal layer, and more particularly to an information recording medium that has excellent corrosion resistance or stability, and in which recording power has a small dependence on linear velocity. Regarding.

Technical Background of the Invention In an information recording medium such as a rewritable magneto-optical disk that has a recording layer and a metal layer on a substrate, the recording power for recording on the recording medium differs greatly between the inner and outer circumferential areas. In order to prevent this, it is desired to reduce the dependence of recording power on linear velocity.

In information recording media such as magneto-optical disks, a metal layer is usually provided on the substrate in addition to the magneto-optical recording layer. Conventionally, the metal layer in information recording media such as magneto-optical disks is made of nickel. Metal layers have been used consisting of aluminum alloys, aluminum metals, or aluminum alloys containing 0.1 to 10% by weight of titanium. However, the metal layer made of aluminum metal or aluminum-titanium alloy has a problem in that it has poor corrosion resistance and cannot withstand long-term use.

In addition, the metal layer made of a nickel alloy has the problem that the recording power required for recording and writing differs greatly between the inner and outer circumferential portions of the disk, and the dependence of the recording power on the linear velocity is still large.

In order to develop an information recording medium that has excellent corrosion resistance and long-term stability, and also has a small dependence of recording power on linear velocity, the present inventors conducted extensive research and found that an aluminum alloy containing at least hafnium or niobium was used. The present invention was completed based on the discovery that an information recording medium having a metal layer has excellent corrosion resistance and that the dependence of recording power on linear velocity is small.

OBJECTS OF THE INVENTION The present invention aims to solve the problems associated with the prior art as described above, and provides an information recording medium that is excellent in corrosion resistance and in which the linear velocity dependence of recording power is small. It is an object.

Summary of the Invention An information recording medium according to the present invention has a recording layer and a metal layer on a substrate, wherein the metal layer is made of at least one kind selected from hafnium (Hl) and niobium (Nb). It is characterized by being made of an aluminum alloy containing the element in an amount of 0.1 to 10 atomic % based on the total number of atoms constituting the aluminum alloy.

Such an information recording medium according to the present invention is made of hafnium (
at least I selected from Hf) and niobium (Nb)
Since it has a metal layer made of an aluminum alloy containing the element (metal) N in an amount of 0.1 to 10 atomic percent, it has excellent corrosion resistance, has low linear velocity dependence of recording power, and It also has excellent layer protection.

DETAILED DESCRIPTION OF THE INVENTION The information recording medium according to the present invention will be specifically described below.

FIG. 1 is a schematic cross-sectional view of an information recording medium according to one embodiment of the present invention, and FIG. 2 is a schematic cross-sectional view of an information recording medium according to another embodiment of the present invention.

In the information recording medium according to the present invention, information written on the recording medium is read out using light such as a laser beam. Specifically, such information recording media include write-once optical discs that cannot erase recorded information but allow additional recording, and furthermore, recordable information that cannot be erased.
Examples include rewritable optical disks such as magneto-optical disks, phase change disks, etc., which are both readable and recordable.

In the information recording medium 1 according to the present invention, for example, as shown in FIG. 1, a recording layer 3 and a metal layer 4 are provided in this order on a substrate 2.

In the present invention, the material of the substrate 2 as described above is not particularly limited, but when the laser beam is incident from the substrate 2#J (arrow A), a transparent substrate is preferable, and specifically, a transparent substrate is used. In addition to inorganic materials such as and aluminum, polymethyl methacrylate, polycarbonate, polymer alloys of polycarbonate and polystyrene, and U.S. Patent No. 4.6
Cyclic olefin random copolymer as disclosed in No. 14.7711, the following cyclic olefin random copolymer (A), poly4-methyl-1-pentene, epoxy resin, polyethersulfone, polysulfone , polyetherimide, and other organic materials can be used. Among these, polymethyl methacrylate, polycarbonate, copolymers as described in US Pat. No. 4,614,778, and the following cyclic olefin random copolymer (A) are preferred.

In the present invention, particularly preferable materials for the substrate include ethylene and the following general formula [I] or [I
A cyclic olefin random copolymer consisting of a copolymer with a cyclic olefin represented by ゛] can be mentioned.

(Blank below) General formula [+] General formula [■'] (In the formula, n is 0 or l, m is O or a positive integer, and R1 and R16 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 RIS to R16 may be bonded to each other to form a monocyclic or polycyclic ring, and the single ring or polycyclic ring is (It may have a double bond, and Rls and R's or R1 and Rts may form an alkylidene group).

... [l] (In the formula [I゛], p is O or an integer of 1 or more, and q
and r is 011 or 2, R1-R1 each independently represents an atom or group from the group consisting of a hydrogen atom, a halogen atom, an aliphatic hydrocarbon, an aromatic hydrocarbon, and an alkoxy group, and R8 (or Re ) and Re(
or R〒) and ] 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 1, preferably O. Moreover, m is 0 or a positive integer, preferably 0 to 3.

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

And R1, R1 (2 [I]), or R1-R15
(Formula [+'l) each represents an atom or group selected from the group consisting of a hydrogen atom, a halogen atom, and a hydrocarbon group. Here, as a halogen source T (!,
Examples include fluorine atom, chlorine atom, odor X atom and iodine atom.

Examples of hydrocarbon groups include alkyl groups having 1 to 6 carbon atoms and cycloalkyl groups having 3 to 6 carbon atoms, and specific examples of alkyl groups include methyl Ethyl 5 Isopropyl 5
Specific examples of cycloalkyl groups include isobutyl penta-amyl group, Table 1 cyclohexyl penta-amyl group.
Cyclopropyl5 Cyclobutyl group Cyclopentyl group can be mentioned.

Furthermore, in the above formula [I'], R5 (or R8) and R
9 (or R) may be bonded via an alkylene group having 1 to 3 carbon atoms, or may be bonded directly without any group.

In the above formula [1], RI S , R
l. may be bonded to each other (together) to form a monocycle or polycycle, and the monocycle or polycycle may have a double bond. Furthermore, Rls and RIM or R1 and R11 may form an alkylidene group. Such alkylidene groups 19 Usually include alkylidene groups having 2 to 4 carbon atoms, and specific examples thereof include tt ethylidene, propylidene
Mention may be made of isopropylidene and imbutylidene groups.

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

The above formula CI] or [I ] Cyclic ore represented by As a fin, in particular, For example, below Examples include such compounds.

(Left below) Bicyclo[2,2,1]hept-2-ene derivatives such as 7-methylbicyclo[2; trimethyltetrasif 8-ethyltetrasif+1]-3-dodecene 8-Hexyltetracy5,8.9.1.0-tetramethy.1-]-]3-dodecene-methyl-9-ethylte8-chlorotetracyph8-promotitracyph8-fluorotetracy+s]-3-dodecene. I@]-3-dodecenes, 1f・+5l-3-dodecene 8-ethylidene-9-iso7・■・]-]3-dodece-dodecene-3-dodecene, 12-S, ill@]-3 -dodecene, 1.]-]3-dodecene, 1-cho.II]-3-dodecene, 12.6,1-cho.1.]-]3-dodecene, 8-n-propylidene 9-dodecene, 8-n- Propylidene-9 8-Isopropylidene[4,4,0,1之・藝、17・1・]-]3-Dodecene-dodecenechloro[4,4,0,1''・S 17・+1]-3-dodecene ·l 8 ], -]3-dodecene-n-propylidene-9 [4,4,0,1"·-17·l spring] -3CH.

Tetracyclo [4,4,0,12・S, 17・I
I]-3-dodecene derivative; (blank below) 8-isopropylidene dodecene 12-methyl hexasifdecentadecene and hexacyclo[6,6,1,1', 6,1 electron...
+ s, Q2, Ding, 09sa] -4-hebutadecene derivative; Decentcosenheptadecene! octacyclo ca, such as 1 ma]-5-tocosene 15-ethyl octacyph 15, 16-cymethylben, 8. o, tt, e, ta, t
, i1, 1・1tj, l @; Ql, I
, Ql! Pentacyclo[6,6,1,1'...(p, te, 0, t
a]-4-hexadecene derivatives; 1,3-dimethylpentaheptacyclo[3,7,0 Hebutacyclo-5-icosene derivatives such as cosene or hephtacyclo-5-heneicosene derivatives; tricyclo[4,4, 0,1′・1]-3-undecene derivative; Tricyclo[4,3,0,1”・s]-3-decene derivative such as 1,3-dimethyl-penta; 1,6-dimethylbentamethyl substitution Pentacyclo[4,7,0,ill, 01.Is, i-tube, +2l-3 such as pentacyclo14,15-dimethylben
-pentadecene derivatives; pentacyclo[6,5,1,12, . Butacyclo [7,8,0,1”...,02,7.II...11,0
-4-eicosene derivatives; -1
・]-]5-bentacocene 5-bentacocene and other nonacyclo[9,10゜1.14・te, 03・so, 02・i・1O1ffi21, l13.21. QI
J, 11.116.11] -5-He: / 9 Kose:
/ Rust conductor etc.

(Margin below) can be mentioned.

(Left below) Ethylene as above and general formula [■] or [I゛]
135 as a copolymer with a cyclic olefin represented by
Intrinsic viscosity [V] measured in decalin at ℃ is 0.05~
In the range of 10dll/H, softening temperature (TMA)
A cyclic olefin random copolymer (hereinafter referred to as cyclic olefin random copolymer [A]) having a temperature of 70° C. or higher is preferably used. Further, if desired, cyclic olefin random copolymer [A]):, ethylene,
A copolymer with a cyclic olefin represented by the following formula [r] or [■°], whose intrinsic viscosity [wa] measured in decalin at 135 ° C. is in the range of 0605 to 5 J / g,
A cyclic olefin random copolymer (hereinafter referred to as cyclic olefin random copolymer [B]) having a softening temperature (TMA) of less than 70° C. may be blended and used.

These cyclic olefin random copolymers [A] and [B] which are copolymers of cyclic olefins and ethylene as described above are copolymers containing 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. -1-pentene, 1-hexene, 1-
Examples include α-olefins having 3 to 20 carbon atoms, such as octene, 1-decene, 1-dodecene, 1-tetradecene, 1-hexadecene, 1-octadecene, and 1-eicosene.

Cyclic olefin random copolymer [A] as described above
repeating unit derived from ethylene (a) ldai
The repeating unit (b) derived from the cyclic olefin is present in an amount of 40 to 85 mol%, preferably 50 to 75 mol%, and the repeating unit (b) derived from the cyclic olefin is present in an amount of 15 to 60 mol%, preferably 25 to 75 mol%.
The repeating unit (a) derived from ethylene and the repeating unit (b) IL derived from the cyclic olefin are present in a range of 50 mol % and are arranged randomly and substantially linearly. The ethylene composition and cyclic olefin composition were measured by IC-NMR. ℃
This can be confirmed by complete dissolution in decalin.

The intrinsic viscosity [wa] of such a cyclic olefin random copolymer [A] measured in decalin at 135°C is
O,OS~10a/g, preferably 0.08~5a
/g range.

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.
The thermal deformation behavior of a sheet with a thickness of one fin was measured using a hanical analyzer.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. The glass transition temperature (Tg) lj of the cyclic olefin random copolymer is usually in the range of 50 to 230°C, preferably 70 to 210°C.

Moreover, x of this cyclic olefin random copolymer [A]! Crystallinity 0-10% measured by s diffraction method,
Preferably 0-796. Particularly preferably 0 to 5%
is within the range of

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 [r] or [I°], which has an intrinsic viscosity [7] of 0.05 to 5 as measured in decalin at 135°C. a
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. .

Cyclic olefin random copolymer CB having a softening point (TMA) of less than 70°C as described above] has a repeating unit derived from ethylene (a) L 60 to 98 mol%,
It is preferably present in an amount of 60 to 98 mol%, and the repeating unit (b) derived from the cyclic olefin is 2
~40 (1'%), female labor 1 or 5 to 40 (%), and the repeating -li position (a) derived from ethylene and the repeating unit (b) derived from the cyclic olefin are , are arranged randomly and substantially linearly.The ethylene composition and cyclic olefin composition are 13C-N
As measured by MR, the fact that this cyclic olefin random copolymer itself [Bl] is substantially linear and does not have a gel-like crosslinked structure means that the copolymer completely dissolves in decalin at 135°C. This can be confirmed by

The intrinsic viscosity of such a cyclic olefin random copolymer [Bl measured in decalin at 135°C [vl is 0
．． 05-5di/g, preferably 0.08-3aQ/g
within the range of

In addition, the softening temperature (TM, A) measured with a thermal mechanical analyzer of a cyclic olefin/1'n rhodium copolytic rock [Bl] is less than +1.70°C, preferably -10 to 6°C.
0°C, and kl' t L < is in the range of 10-55°C. Furthermore, the glass-flip temperature (Tg) of the cyclic olefin-based random copolymer [Bl] is -30～
60℃1. 11. Preferably, the temperature is in the range of -20 to 50°C. stomach.

In addition, the crystallinity of this cyclic olefin random copolymer [X of Bl, 49 measured by diffraction method is 0 to 1]
0%, preferably 0-7%, particularly preferably 0-5%
is within the range of

In the present invention, when using the cyclic olefin random copolymer [A] and [Bl as the substrate, the polymer i ratio of the cyclic olefin random copolymer [A]/the cyclic olefin random copolymer [Bl] ha1oo10.1-
100/10. Favorite L < Ifl, 0O10,3
-1007'I, particularly preferably 10010.5~
A range of 1.0015 is desirable. [B] Acid component By blending the [A] acid component within this range, the substrate itself can adhere to the reflective film used in the present invention under severe conditions while maintaining its excellent transparency and surface smoothness. The gender is [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 made of a blend of [A] and [Bl is used as a substrate, the reflective film used in the present invention can be improved. Excellent adhesion at high temperatures?
:1Ji5 It has the characteristic that there is no change even after being left under conditions.

The above cyclic olefin copolymers [A] and [Bl constituting the substrate in the present invention are disclosed in Japanese Patent Application Laid-Open No. 60168708.
Ji3 Public Book JP-A-61. -120816 Publication JP-A-61-115912 Public Corporation JP-A-61-11591
Public Corporation No. 6 JP 62-252406 Public IL JP 62-25240'7 JP 61-2713
It can be produced by appropriately selecting conditions according to the method proposed by the present applicant in Publication No. 08-a and Jikai Publication No. 61-272216.

In such a cyclic olefin random copolymer, the structural unit (b) derived from the cyclic olefin represented by the above formula [I] or [I゛] is represented by the following formula [n] or [I゛]. Some of the structural units (b) considered to form the repeating units of the structure shown may be bonded together by ring-opening polymerization, and hydrogenation can also be performed if necessary. be.

...[n 1 (in the formula [■゛], m, -n, RI, R+ e are the same as the definitions in the above formula [1F]) ... [n 1 (in the formula [■゛], pl Ql r and R14RI %
is the same as the definition in the above formula [I']. ) As a substrate of the magneto-optical recording medium according to the present invention (as described above, a cyclic copolymer of the above-mentioned random copolymer of ethylene and a cyclic olefin is used). Olefin ring-opening polymerization Ring-opening copolymers or hydrogenated products thereof can also be used.

Such a cyclic olefin ring-opening polymerization method To explain the ring-opening copolymers and their hydrogenated products using the cyclic olefin represented by the formula [I] as an example, the ring-opening copolymers and their hydrogenated copolymers are reacted and opened as described below. It is thought that it constitutes a ring 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, ring-opening copolymer, these hydrogenated products, and the cyclic olefin random copolymer is modified with an unsaturated carboxylic acid such as maleic anhydride. You can. Such modified products can be produced by reacting the above-mentioned cyclic olefin resin with unsaturated carboxylic acids, their anhydrides, and derivatives such as alkyl esters of unsaturated carboxylic acids. In this case, the content of structural units derived from the modifier in the modified cyclic olefin resin is usually 50 to 10 mol% or less. It can also be produced by blending a modifier with a cyclic olefin resin and performing graft polymerization. It can also be produced by mixing.

In the present invention, the above-described ring-opening polymerization, ring-opening copolymer, hydrogenated product thereof, cyclic olefin random copolymer, and modified product thereof can be used alone or in combination.

Further 1 In the present invention, when producing the above-mentioned cyclic olefin random copolymer, the formula [I] or [r', 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-(2-methylbutyl)-1-cyclohexene,
3.3a, 7a-tetrahydro-4,7-methano-I
H-indene 3a, 5.6.7a-tetrahydro-4,7-methano-
Examples include IH-indene. Such other cyclic olefins can be used alone or in combination, and are usually used in an amount of 0 to 50 mol%.

Further, on the substrate of the magneto-optical recording medium according to the present invention (the above [A
] and [B] Acid components, etc. Rubber components are added to improve impact strength, heat resistant stable ship weather resistant ship anti-static agent L slip ship anti-blocking anti-fog mh rltsh dyes, pigments, natural demons synthetic Method Wax etc. can be blended, and the blending ratio is appropriate. For example, as a stabilizer that is added as an optional component, 1 ml of tetrakis [methylene-3] is added to the CC pot body.
(3,5-di-7-butyl-4-hydroxyphenyl)
Propionate comethane, β-(3,5-di-t-butyl-4-hydroxyphenyl)propionic acid alkyl ester, 2,2°-oxamidobis[ethyl-3(3,
Phenolic antioxidant K such as 5-di-t-butyl-4-hydroxyphenyl)cobropionate, fatty acid metal salts such as zinc stearate, calcium stearate, calcium 12-hydroxystearate, glycerin monostearate, glycerin monolaurate, glycerin Examples include fatty acid esters of polyhydric alcohols such as distearate, pentaerythritol monostearate, pentaerythritol distearate, and pentaerythritol tristearate. These may be blended alone or in combination; for example, tetrakis[methylene-3 (3°5-di-
Examples include a combination of 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. Polyhydric alcohol fatty acid esters are preferred.

Such fatty acid esters of polyhydric alcohols (specifically 1) glycerin fatty acid esters such as glycerin monostearate, glycerin monolaurate, glycerin monomyristate, glycerin monopalmitate, glycerin distearate, glycerin dilaurate, Fatty acid esters of pentaerythritol such as pentaerythritol monostearate, pentaerythritol monolaurate, pentaerythritol dilaurate, pentaerythritol distearate, and pentaerythritol tristearate are used.

Such a phenolic antioxidant 1 [-A
] component and CE [used in an amount of 0 to 10 parts by weight, preferably 0 to 5 parts by weight, and more preferably 0 to 2 parts by weight, based on 100 parts by weight of the total weight of the components. It is used in an amount of 0 to 10 parts by weight, preferably 0 to 5 parts by weight, based on 100 parts by weight of the total weight of A] acid component and [B] acid component.

1 on the substrate of the magneto-optical recording medium according to the present invention Silica, diatomaceous earth, alumina,
Titanium oxide, magnesium oxide, pumice powder, pumice balloon, aluminum hydroxide, magnesium hydroxide, basic magnesium carbonate, dolomite, calcium sulfate, potassium titanate, Vts barium, calcium sulfite, talc, clay mica, asbestos, glass fiber glass Flakes, glass peas, calcium silicate, montmorillonite, bentonite, graphite, aluminum powder, molybdenum sulfide, boron beads, silicon carbide beads
Polyethylene textile machine Polypropylene edge Polyester fabric Filler such as polyamide fiber may be added.

In the present invention, if a cyclic olefin-based random copolymer or cyclic olefin-based random copolymer composition as described above is used as a substrate, polycarbonate, poly(meth)acrylate, etc. may be used as a substrate, although the reason is not clear. Compared to conventional magneto-optical recording media, recording sensitivity is improved. In addition, the substrate made of this cyclic olefin random copolymer or a composition containing this copolymer and the recording layer laminate have excellent adhesion, and therefore the recording film has excellent long-term stability and is resistant to oxidation. effectively prevented. Therefore, an optical recording medium formed by laminating a recording film on a substrate made of this cyclic olefin random copolymer is advantageous in terms of 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 2 is not particularly limited, but is preferably 0.5 to 5. Particularly preferably 1 to 2 yen.

Further, in the present invention, the material of the recording layer 3 is not particularly limited, but for example, when the recording layer 3 is a magneto-optical recording layer having uniaxial anisotropy in the direction perpendicular to the film surface, the recording layer 3 is , (i) at least one selected from 3d transition metals;
(Iii) at least one element selected from rare earths, or (i) at least one element selected from 3d transition metals, (i) a corrosion-resistant metal, and (...) at least one element selected from rare earths. Preferably, it consists of a species element.

(i) 3d transition metals include Fe, Co, and Ti.

(2) Cr, Mnx Ni, Cu, Zn, etc. are used, and among these, Fe, Co, or both are preferable.

(i) By including a corrosion-resistant metal in the recording layer 3, the oxidation resistance of the magneto-optical recording layer can be improved. Such corrosion-resistant metals include Pt, Pd, and Ti.
, Zr5Ta, Mo, Nb.

Among these, Pt and Pd are used.

TI is preferred, especially pt and/or Pd.

(i) As the rare earth element, for example, Gd1Tb.

Dy%Ho5E r, Tm, Yb, Lu, La.

Ce, Pr, Nd, Pm, Sms Eu, etc. are used.

Kono Uchi G d ST b s D y SHo, N
d%S m sPr is preferably used.

In such a magneto-optical recording layer, (i) the 3d transition metal is
in an amount of 30 to 85 atom %, preferably 40 to 70 atom %,
(i) Corrosion resistant metal up to 30 atomic %, preferably 5 to 2
Desirably, (i) the rare earth element is present in an amount of 5 to 50 atom %, preferably 25 to 45 atom %, in an amount of up to 5 atom %.

When the recording layer 3 is a phase change type recording layer other than a magneto-optical recording layer, the recording layer 3 is, for example, an alloy thin film mainly composed of Te, an alloy thin film mainly composed of Se, a Te
-Ge-3b alloy thin film, In-3b-Te alloy thin film, T
It is composed of an e-Ge-Cr alloy thin film, a Te-Ge-Zn alloy thin film, etc. Furthermore, an organic dye film made of a polymethine compound, a cyanine compound, or the like can also be used as a write-once type or phase change type recording layer.

In the present invention, the thickness of the recording layer 4 is not particularly limited, but
The number is 50 to 5000 people, preferably 100 to 2000 people.

In the present invention, the metal layer "4" in such an information recording medium contains at least IFli element (metal) selected from hafnium and niobium in an amount of 0.1 to 10, based on the total number of atoms constituting the aluminum alloy. It is formed from an aluminum alloy containing an amount of atomic percent.

Specifically, the metal layer 4 is an aluminum alloy containing hafnium (Hl) in an amount of 0.1 to 10 atomic %, preferably 1 to 6 atomic %, based on the total number of atoms constituting the aluminum alloy, or 0.1 atomic %. It is formed from an aluminum alloy containing niobium (Nb) in an amount of 1 to 10 atomic %, preferably 1 to 6 atomic %, or an aluminum alloy containing both hafnium and niobium in a total amount of 0.1 to 10 atomic %.

In addition to aluminum, hafnium and/or niobium, the metal layer 4 as described above can also contain one or more other metals (elements) of natural nails. Examples of such metals include chromium (CI, in the case of Al-Nb alloy), silicon (Sl), tantalum (TI), copper (
CI), tungsten (D, zirconium (2+)
, manganese (Mu), magnesium (Ml, Al
-Nb alloy), vanadium (Y), etc., and such other metals are usually present in the aluminum alloy.
It is contained in an amount of at most atomic %, preferably at most 2 atomic %.

The thickness of the metal layer as described above is usually 100 to 50 mm.
00 people, preferably 500 to 3000 people, particularly preferably 700 to 2000 people.

The metal layer according to the present invention functions as a good thermal conductor layer, and the presence of this metal layer prevents the center of the bit recorded on the recording layer from becoming excessively hot due to the recording laser beam. This is considered to be because the dependence of the recording power on the linear velocity becomes smaller.

In addition, the metal layer in the present invention has excellent corrosion resistance, so even after long-term use, the linear velocity dependence of the recording medium is small, and it also has an excellent protective effect on the recording layer. ing.

The information recording medium according to the present invention is not limited to the configuration shown in FIG. 1, but is, for example, as shown in FIG. , a recording layer 3 and a metal layer 4 may be laminated thereon. Also the third
As shown in the figure, a first protective film 5 is laminated on a substrate 2, a recording layer 3 is laminated thereon, and a second protective film 11 is further laminated thereon.
115 and the metal film 4 may be sequentially laminated. As such a protective film (enhancement film) 5, Si3N4,
S iNx (0<x<4/3), AlN5ZnSe
.

It is preferably formed from Zn5SSi or CdS, but is not limited thereto. The thickness of such a protective film is about 100 to 2000, preferably about 300 to 1500. Among these, SiN, 5iNx (
It is preferable to use 0<x<4/3).

The protective film serves to protect the recording film and, in some cases, increases the sensitivity of the information recording medium and also serves as an enhancement film. Preferably, such a protective film has a refractive index H that is larger than the refractive index of the substrate.

In the information recording medium according to the present invention, a recording layer, a metal layer, and, if necessary, a protective layer are formed on a substrate by a film forming method such as a vacuum evaporation method, a sputtering method, or an electron beam evaporation method. It can be manufactured by

Effects of the Invention As described above, the information recording medium according to the present invention contains at least one element (metal) selected from hafnium and niobium.
Because it has a metal layer made of an aluminum alloy containing 0.1 to 10 at% of Are better.

The present invention will be explained below with reference to examples, but the present invention is not limited to these examples.

Note that in this specification, the optimum recording power is f=IM
Hz, d+l! Represents the recording power at which the second harmonic of the reproduced signal is minimum with respect to 50% of the write signal.
The smaller the difference in optimal recording power due to linear velocity, the smaller the linear velocity dependence.

Example 1 First, the IT corrosion resistance of the metal layer was examined as follows.

A metal layer of an aluminum-hafnium alloy with a thickness of 700 mm was deposited on a glass substrate by sputtering using an aluminum-hafnium composite target. Aluminum alloy (
The hafnium content in the layer) was 4 atomic %, and the aluminum content in the aluminum alloy was 96 atomic %.

This metal layer was immersed in a 10% by weight aqueous sodium chloride solution at 60° C. for 4 hours, and the corrosion resistance of the metal layer was evaluated by measuring the change in reflectance.

The reflectance of a metal worker is 1J2f after immersion in a sodium chloride aqueous solution.
iii and '&' did not change after iJ1.

Example 2 A metal layer of aluminum niobium alloy having a thickness of 700 mm was deposited on a glass substrate by sputtering using a composite target of aluminum niobium.

The content of niobium in the aluminum alloy (layer) constituting the obtained metal layer was 4 at%, and the aluminum alloy (
The aluminum content in the layer) was 96 at.%.

This metal layer was immersed in a 10% by weight aqueous sodium chloride solution at 60° C. for 4 hours, and the corrosion resistance of the metal layer was evaluated by measuring the change in reflectance.

The reflectance of the metal layer did not change before and after immersion in the sodium chloride aqueous solution.

Comparative Example 1 A metal layer made of aluminum with a thickness of 700 mm was deposited on a glass substrate by sputtering using an aluminum target.

This metal layer was immersed in a 10% by weight aqueous sodium chloride solution at 60° C. for 4 hours, and the corrosion resistance of the metal layer was evaluated by measuring the change in reflectance.

The reflectance of the metal layer after being immersed in an aqueous sodium chloride solution was approximately 30% lower than before immersion.

Example 3 - Ethylene content 59 mol % determined by NMR analysis, DM
(Contains IN, 1141 mol%, intrinsic viscosity [η] measured in decalin at 135°C is 0.42 dj!/g, softening temperature (
A protective film made of Si3N4 with a thickness of 1100 and a Pj with a thickness of 260
A recording film made of 10T b 29F e ssCOt was sequentially laminated by sputtering, and a metal layer made of an aluminum-hafnium alloy with a thickness of 700 nm was deposited on this recording film by sputtering using an aluminum-hafnium composite target. were laminated. The content of hafnium in the aluminum alloy (layer) constituting the obtained reflective metal layer was 4 atomic %.

The obtained information recording medium was kept in an atmosphere of 80° C. and 85% relative humidity for about 720 hours, and the corrosion resistance of the metal layer and the protection performance of the metal layer for the recording layer were evaluated by changing the reflectance of the information recording medium. It was evaluated by measuring.

The reflectance of the information recording medium did not change before and after being held in an atmosphere of 80° C. and 85% relative humidity.

Example 4 Example 3 was carried out in the same manner as in Example 3 except that the thickness of the metal layer was 500 people.

After the obtained information recording medium was kept in an atmosphere of 80° C. and relative humidity of 85% for about 720 hours, the reflectance of the information recording medium was measured, and the reflectance did not change.

The optimum recording power of this information recording medium at a linear velocity of 5.7 m/sec is 3.7 mW, and at a linear velocity of 11.3 m/sec, the optimum recording power is 3.7 mW.
The optimum recording power at c was 5.2 mW.

Comparative Example 2 On the same substrate as used in Example 3, a protective film made of Si3N4 and a recording film made of P t IOT b 29F e ssCOt were sequentially laminated by sputtering method, and aluminum was deposited on this recording film. A metal layer made of aluminum with a thickness of 700 mm was laminated by sputtering using a target.

The obtained information recording medium was kept in an atmosphere of 80° C. and 85% relative humidity for about 720 hours, and the corrosion resistance of the metal layer was evaluated by measuring the change in reflectance of the information recording medium.

The reflectance of the information recording medium after holding the recording medium in an atmosphere of 80° C. and 85% is about 1 compared to before holding.
It decreased by 5%.

[Brief explanation of drawings]

FIG. 1 is a schematic cross-sectional view of an information recording medium according to one embodiment of the present invention, and FIG. 2 is a schematic cross-sectional view of an information recording medium according to another embodiment of the present invention. 1... Information recording medium 2... Substrate 3... Recording layer 4... Metal layer 5... Protective film

Claims (1)

[Claims] 1. An information recording medium having a recording layer and a metal layer on a substrate, in which the metal layer contains at least one element selected from hafnium and niobium, based on the total number of atoms constituting the aluminum alloy. . An information recording medium comprising an aluminum alloy containing 1 to 10 atomic %.