JPH0373443A - Information recording medium - Google Patents

Abstract

PURPOSE:To improve corrosion resistance and to lessen the dependency of a recording power on a line speed by providing a metallic layer consisting of an aluminum alloy contg. specific ratios of chromium and hafnium. CONSTITUTION:A recording layer 3 and the metallic layer 4 are provided on a substrate 2. The metallic layer 4 is constituted of the aluminum alloy which contains 0.1 to 5 atomic% chromium and 0.1 to 9.5 atomic% hafnium based on the total atomic number constituting the aluminum alloy and is of <= 10atom ic% in the total content of the chromium and the hafnium. The corrosion resis tance is improved in this way and the dependency of the recording power on the line speed is lessened. In addition, the protective effect of the recording layer 3 is improved.

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 parts. In order to avoid this, it is desired to reduce the linear velocity dependence of recording power.

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. Gold dust layers have been used that are made 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 serious problem in that it has poor corrosion resistance and cannot withstand long-term use.

In addition, metal layers made of nickel alloys have the problem that depending on the type of alloy, the recording power required for recording and writing differs greatly between the inner and outer periphery of the disk, and the recording power still has a large linear velocity dependence. was there.

In order to develop an information recording medium that has excellent corrosion resistance and long-term stability, and also has low linear velocity dependence of recording power, the present inventors have made extensive studies on aluminum alloys containing at least hafnium or niobium. The present invention was completed based on the discovery that an information recording medium having a metal layer consisting of the following 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 A first information recording medium according to the present invention has a recording layer and a metal layer on a substrate, the metal layer comprising:
Chromium: 0.1 to 5 at.% Tohafnium: 0.1 to 5 at.% based on the total number of atoms constituting the aluminum alloy. chromium and hafnium, and the total content of chromium and hafnium is 10 at % or less.

A second information recording medium according to the present invention is an information recording medium having a recording layer and a metal layer on a substrate, wherein the metal layer is
Based on the total number of atoms constituting the aluminum alloy (i
) 0.1 to 5 at% chromium; (i) 0.1 to 9 titanium;
．． 5 at.% and (ii) 0.1 to 9.5 at.% of hafnium, and the total content of chromium, titanium, and hafnium is 10 at.% or less.

Such a first information recording medium according to the present invention contains 0.1 to 5 at.% of chromium and 0.1 to 9.5 at.% of hafnium, and the total content of chromium and 71 hnium is 1.
The second information recording medium according to the present invention has a metal layer made of an aluminum alloy of 0 atomic % or less,
(i) 0.1 to 5 at% chromium; (i) 0.1 titanium
~9.5 at.% and (i) hafnium 0.1-9.5
% and the total content of chromium, titanium, and hafnium is 10 atomic % or less, so it has excellent corrosion resistance and also has low linear velocity dependence of recording power. It is small and has an excellent protective effect on the recording layer.

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 FIGS. 2 and 3 are schematic cross-sectional views of information recording media according to other embodiments 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 and phase change disks that 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 side (arrow A), a transparent substrate is preferable, and specifically,
In addition to inorganic materials such as glass and aluminum, polymethyl methacrylate, polycarbonate, and polymer alloys of polycarbonate and polystyrene, U.S. Patent No. 4.61
Cyclic olefin random copolymer as disclosed in No. 4.778, the following cyclic olefin random copolymer (A), poly4-methyl-1-pentene, epoxy resin, polyether sulfone, polysulfon , 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 preferred materials for the substrate and j are ethylene and the following general formula [I] or [
A cyclic olefin-based random copolymer consisting of a coelectrolyte with a cyclic olefin represented by I' is exemplified.

(Left space below) General formula [r] (In the formula, n is O or l, m is O or a positive integer, and R1 to R are each independently a hydrogen atom, a halogen atom, and a hydrocarbon Represents an atom or group selected from the group consisting of R1%~Rl@l,i, which may be bonded to each other to form a monocyclic or polycyclic ring, and the monocyclic or polycyclic ring has a double bond. RIs and R16 or RIT and R18 may form an alkylidene group).

General formula [■°] ・ [1'co (In formula [I°], p is O or an integer of 1 or more, and q
and rIt, Oll or 2, RI~R111
each independently represents an atom or group from the group consisting of a hydrogen atom, a halogen atom, an aliphatic hydrocarbon group, an aromatic hydrocarbon group, and an alkoxy group; R& (or R.) and R
- (or R?) and L 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 O or 1, preferably O. Moreover, m is O or a positive integer, preferably O-3.

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

and R1 to RIB (formula [I]), or R1 to R1
(Formula [r']) l & each independent number; hydrogen atom,
Represents an atom or group selected from the group consisting of a halogen atom and a hydrocarbon group. Here, 1 as a halogen atom
For example, fluorine atom, chlorine atom, bromine atom and iodine atom can be mentioned.

In addition, examples of hydrocarbon groups include +4, alkyl groups usually having 1 to 6 carbon atoms, and cycloalkyl groups having 3 to 6 carbon atoms, and specific examples of alkyl groups include (also methyl salts) Ethyl group, isopropyl group, isobutyl group, amyl group, and specific examples of cycloalkyl groups include 19 cyclohexyl group, cyclo, propyl group, cyclobutyl group, cyclopentyl group.

In the above formula [y'], R6 (or R11) and Re (or R?) may be bonded via an alkylene group having 1 to 3 carbon atoms, or without any group. They may be directly combined.

Furthermore, in the above formula [1], RI l -y R'
* may be bonded to each other (together) to form a monocyclic or polycyclic ring, and the monocyclic or polycyclic ring may have a double bond. Also, Rls and Rls or R
1 and R1 may form an alkylidene group.

Such an alkylidene group 11 usually has 2 carbon atoms
-4 alkylidene groups can be mentioned, and specific examples thereof include ethylidene group, propylidene group, isopropylidene group and isobutylidene group.

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

Specific examples of the cyclic olefin represented by the formula [I] or [■'] include the following compounds.

(Left below) Bicyclo[2,2,1]hept-2-ene derivatives such as 7-methylbicyclo[2; 5.10-dimethyltetraCH.

CI(S CHa 2.10-dimethyltetra2,7.9-)limethylthene5,8.9.10-tetramethy(blank below) 9-inbutyl-2,7-9,11,12-)dimethyl9-ethyl -11,12-dime9-inbutyl-11,12-dodecene-8-methyltetrasif-8-ethyltetrasif-1-]-3-dodecene-1-]-]3-dodecene-methyl-9-ethyltetrasif-8-chloro Tetrasif 8-promotitrasif 8-fluorotetracyt.]-]3-dodecene1.]-]3-dodecene-ethylidene-9-ethyne 8-ethylidene-9-iso-dodecene 1z, s, 1 piece, 1 m. -] 3-dodecene, 1 ma, +s]-3-dodecene 8-n-propylidene-9 1-dodecene! , lT, l@]-3-dodecene l・]-]3-dodecene3-dodecene・+@1-3-dodecene12 5.17・]-3-dodecene8-n-propylidene-9 [4 ,4,0,1"・s,1γ"・]-]3-dodecene-]-]3-dodecene-n-propylidene-9 [4,4,0,lt-8,1′・st]-3 -dodecene, 8-impropylidene, dodecene, 8-isopropylidene, dodecene, 12-methylhexacyfdecene, ]-]3-dodecene, dodecene, etc., tetracyclo[4,4,0,12,5.17+s
Co-3-dodecene derivatives; Heptadecene (blank below) 15-ethyloctacyphth Q2, 7,09, Co-4-heptadecene and other hexacyclo[6,6,1,1ffs, 10 +3. Q2. ? , Q11 , +4]-4-heptadecene derivatives; such as octacyclo[8,8,0,12・9.14・?
, II l・l・1+S, II, Qll, QIII
7], -5-tocosene derivative; pentacyclo[6,6
,1 Tokosen Monguchi・,10 +8. QL・Q+ Hebutacyclo-5-icosene derivatives such as 10teco-5-docosene or hebutacyclo-5-heneicosene derivatives; l1m Nopene such as sen! '/ Kuro [6, 6, 1, IL'&, 0
2-",0'-"]-]-4-hexadecene derivatives; any tricyclo[4,,3,0,12@]-3-decene derivatives; tricyclo[4,,3,0,12@]-3-decene derivatives; [4,4,0,12·S]-3-undecene derivatives; such as pentacyclo[6,5,1,it@, Q2.7.
Qlltl-4-pentadecene derivatives; diene compounds such as; methyl-substituted pentasi, 21. 1 hour 121. Qli, ll, 11L] Pentacyclo such as -5-bentacocene [47, Q, 12. s, Qli, +3. pX2 co-3-pentadecene derivative; cosene-5-bentacosenna J:'f)) Nasik T:1 [9,10,1,1'
-', O'1.02-", O", 11.113. tl,
Qli, lI, 111. +s]-5-Henta:7 Sen1 conductor, etc. can be mentioned.

(Margin below) 2.16] -4-Eikosen Hebutacyclo such as [7,8,0,1”,02 7.1st eye Eye, 0 Ill, 11111] -4-eicosene derivative; And furthermore, 5-phenyl-bicyclo[ can be mentioned.

(The following is a blank space) As a copolymer of ethylene as described above and a cyclic olefin represented by the general formula [+1 or (yo[I゛]), 1
Intrinsic viscosity [η] measured in decalin at 35°C is 0.0
Range of 5 to 10d51/g (temperature (T)
Cyclic olefin random copolymer (hereinafter referred to as cyclic olefin random copolymer [A]) whose MA) is 70°C or higher
) is preferably used as I/1. Also, if desired,
Cyclic olefin random copolymer [A]t: A copolymer of ethylene and a cyclic olefin represented by the following formula [1] or (yo [■°]), measured in decalin at 135 ° C. The intrinsic viscosity [vl is 0.05 to 5 dil]
/H range, with a soft IK degree (TMA) of 70
℃ or below (hereinafter referred to as cyclic olefin random copolymer [B]).

These cyclic olefin random copolymers [A] and [B] are copolymers of cyclic olefins and ethylene as described above! L A force having ethylene and the above-mentioned cyclic olefin as essential components C1 In addition to the two essential components, if necessary, other copolymerizable unsaturated monomers may be added within the range of L and 1 that do not impair the object of the present invention. It may contain a mercury component. Specifically, the unsaturated monomer which may be optionally copolymerized includes, for example, propylene in a mole less than equimolar to the ethylene content unit in the random copolymer to be produced;
1-butene, 4-methyl-1-pentene, 1-hexene, 1-octene, 1-decene, 1-dodecene, 1
Examples include α-olefins having 3 to 20 carbon atoms, such as -tetradecene, 1-hexadecene, 1-octadecene, and 1-eicosene.

Cyclic olefin random copolymer [A] as described above
19 Repeating unit derived from ethylene (a) 11
40 to 85 mol%, preferably present in a range of 50 to 75 mol%, and the repeating unit (b) derived from the cyclic olefin is present in a range of 15 to 60 mol%, preferably 25 to 75 mol%.
A repeating unit (a) derived from ethylene and a repeating unit (b) derived from the cyclic olefin, present in a range of 50 mol% +1. They are randomly arranged in a linear pattern. The ethylene composition and cyclic olefin composition were measured by C-NMR. is 1
This can be confirmed by complete dissolution in Deca-Q at 35°C.

In such a cyclic olefin random copolymer [A]
Intrinsic viscosity measured in decalin at 135°C ['7]
1&0.05 to 10dff/g, preferably in the range of I&0.08 to 5ax/g.

In addition, the softening temperature (T
MA) is 70°C or higher, preferably 0 to 250°C from 1,
More preferably, the temperature is in the range of 100 to 200°C. The softening temperature (TMA) is 14.Therm manufactured by DuPont
Using an omechanical analyzer 1. )
The temperature was measured by the thermal deformation behavior of a sheet with a thickness of 1.
The temperature is raised at a rate of °C/min, and the temperature at which the needle penetrates by 0.635°C is taken as TMA.The glass transition temperature (Tg) of the cyclic olefin random copolymer is usually 50 to 2
It is desirable that the temperature is 30°C, preferably in the range of 70 to 210°C.

Also, the crystallinity of this cyclic olefin random copolymer [A] measured by X@ diffraction method! 40-10%,
The range is preferably from 0 to 7%, particularly preferably from 0 to 5%.

In the present invention, the softening temperature (TMA) as described above is also provided.
Cyclic olefin random copolymer [A] & gas ethylene whose temperature is 70°C or higher, and the above formula [rl or [! A copolymer with a cyclic olefin represented by
The substrate is preferably formed from a cyclic olefin random copolymer composition containing a cyclic olefin random copolymer [B] having a softening temperature (TMA) of less than 70°C.

In the cyclic olefin random copolymer [B] having a softening point (TMA) of less than 70°C as described above, repeating units (a) + f derived from ethylene, 60 to 98 mol%, preferably 60 to 98 mol% It exists within the range of
Further, the repeating unit (b) derived from the cyclic olefin is present in a range of 2 to 40 mol%, preferably 5 to 40 mol%, and the repeating unit (a) derived from ethylene and the cyclic olefin are present in a range of 2 to 40 mol%, preferably 5 to 40 mol%. The repeating units (b) are arranged in a random, substantially linear manner. The ethylene composition and cyclic olefin composition were not measured by 13 cm NMR. This can be confirmed by complete dissolution in decalin at °C.

Intrinsic viscosity [7] of such a cyclic olefin random copolymer [B] measured in decalin at 135°C (conversion
0.05-5. Ml/g, preferably 0.08-3
It is in the range of an/g.

In addition, the softening temperature (T
MA) 1k 70℃ unheated, preferably -10~60
℃, more preferably in the range of 10 to 55℃. Further I Glass transition temperature (Tg) L of the cyclic olefin random copolymer [B] It is usually in the range of -30 to 60°C, preferably in the range of -20 to 50°C.

In addition, the crystallinity of this cyclic olefin random copolymer [B] measured by X@ diffraction method is 10 to 10%,
Preferably it is in the range of 0 to 7%, particularly preferably in the range of 0 to 5%.

In the present invention, when cyclic olefin random copolymers [A] and [B] are used as the substrate, the weight of the cyclic olefin random copolymer [A]/the cyclic olefin random copolymer [B] The ratio is 10010.1~
100/10, preferably Zoolo, 3-100/
7, particularly preferably in the range of 10010.5 to 10015. By blending [B] with the acid component [A] within this range, the substrate itself can maintain excellent transparency and surface smoothness while maintaining adhesion to the reflective film used in the present invention under severe conditions. is further improved compared to the case where only the [A] acid component is used, and if the above-mentioned cyclic olefin random copolymer composition made of a blend of [A] and [B] is used as a substrate, the present invention can be achieved. The excellent adhesion with the reflective film used does not change even after being left at high temperatures and under high temperature conditions.

The above cyclic olefin copolymers [A] and [B] constituting the substrate in the present invention are disclosed in Japanese Patent Application Laid-Open No. 60-16870.
No.8 Public/Private JP-A-61-120816 Public-Private JP-A-6
1-115912 Public/Private JP 61-115916 Public/Private JP 62-252406 Public/Private JP 62-
It can be produced by appropriately selecting conditions according to the method proposed by the applicant in JP-A-61-272216, Publication No. 252407, Public Corporation 411yJ.

In such a cyclic olefin random copolymer, the structural unit (b) derived from the cyclic olefin represented by the above formula [I] or [■'] is represented by the following formula [ml or [■°]]. Force C1 Some of the structural units (b) that are considered to form the repeating units of the structure may be bonded together by ring-opening polymerization, and hydrogenation can also be performed if necessary.

... [Il] (In formula [n], m, n and RI-Rt.
] is the same as the definition in . ) (In formula [n'], p, q, r and R1 to R1
'llfThis is the same definition as in the above formula [work]. )
As mentioned above, the substrate of the magneto-optical recording medium according to the present invention is a cyclic copolymer of ethylene and a cyclic olefin obtained by ring-opening the same or different cyclic olefin monomers. Olefin ring-opening type binding
Ring-opened copolymers or hydrogenated products thereof can also be used. Such cyclic olefin ring-opening polymerization images Regarding ring-opening copolymers and hydrogenated products thereof, the above formula [I
Taking the cyclic olefin represented by 2 as an example, it is thought that it reacts as described below to form a ring-opened copolymer and a hydrogenated product thereof.

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

In the present invention, the above-mentioned ring-opening type bonded paper. You can leave it there. One such modified product 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.

Such a modified cyclic olefin resin can be produced by blending a modifier with a cyclic olefin resin to achieve a desired modification rate and graft polymerization, or by preparing a modified product with a high modification rate in advance. It can also be produced by subsequently mixing this modified product with an unmodified cyclic olefin resin.

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

Furthermore, in the present invention (9) When producing the above-mentioned cyclic olefin random copolymer, the cyclic olefin-based random copolymer represented by the above formula [I] or [I'] is Cyclic olefins other than olefins can also be polymerized. Examples of such cyclic olefins include (!, cyclobutene, cyclopentene, cyclohexene, 3.4-dimethylcyclohexene, 3-methylcyclohexene, 2-(2-methylbutyl)-1 -cyclohexene, 2,
3.3a, 7a-tetrahydro-4,7-methano-
Examples include IH-indene, 3a, 5.6.7a-tetrahydro-4,7-methano-IH-indene, and the like. Such other cyclic olefins can be used alone or in combination, and are usually used in an amount of 0 to 50 mol%.

Further, the substrate of the magneto-optical recording medium according to the present invention has the above-mentioned [A
] and [B] In addition to the active ingredients, rubber components to improve impact strength may be blended, heat resistant stabilizer, weather resistant stabilizer, antistatic material, slip material, anti-blocking material.
Anti-fog agent L Lubricant L Dyes, pigments, natural waxes, etc. can be blended, and the blending ratio is appropriate. Specifically, as a stabilizer to be added as an optional component of IA, 19 tetrakis[methylene-3(3,5
-di-t-butyl-4-hydroxyphenyl)propionate comethane, β-(3,5-di-t-butyl-4-
hydroxyphenyl) propionic acid alkyl ester,
2.2'-oxamidobis[ethyl-3(3,5-di-
Phenolic antioxidants such as t-butyl-4-hydroxyphenyl]propionate, fatty acid metal salts such as zinc stearate, calcium stearate, and calcium 12-hydroxystearate, glycerin monostearate, glycerin monolaurate, and glycerin distear Examples include fatty acid esters of polyhydric alcohols such as ester, pentaerythritol monostearate, pentaerythritol distearate, and pentaerythritol tristearate. These may be blended alone or in combination, such as IL tetrakis[methylene-3 (3°5-di-t-
Examples include a combination of butyl-4-hydroxyphenyl)propionate comethane, zinc stearate, and glycerin monostearate.

In the present invention, it is preferable to use a combination of a phenolic antioxidant and a fatty acid ester of a polyhydric alcohol.
It is preferable to use a polyhydric alcohol fatty acid ester in which a part of the alcoholic hydroxyl groups of a polyhydric alcohol having a higher valence or higher are esterified.

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

Such phenolic antioxidant II iL [
A] acid component and [B] acid component 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 acid component; and fatty acids of polyhydric alcohols. The ester 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 the acid component [A] and the acid component [B].

The substrate of the magneto-optical recording medium according to the present invention (9) If necessary, silica, diatom, alumina, titanium oxide, magnesium oxide, pumice powder, pumice balloon, hydroxide, etc. Aluminum, magnesium hydroxide, basic magnesium carbonate, dolomite, calcium sulfate, potassium titanate, barium sulfate,
Calcium sulfite, talc, clay Mica, asbestos, glass woven rim Glass flakes, glass beads, calcium silicate, montmorillonite, bentonite, graphite, aluminum powder, molybdenum sulfide, boron fiber Silicon carbide woven rim Polyethylene fiber polypropylene fiber Polyester woven Edge Filler such as polyamide fiber may be added.

In the present invention, when a cyclic olefin random copolymer or a cyclic olefin random copolymer composition as described above is used as a substrate, the cyclic olefin random copolymer or a composition containing the copolymer Since the substrate and the recording layer or protective layer have excellent adhesion, the recording film has excellent long-term stability and oxidation of the recording film is effectively prevented. Therefore, the optical recording medium 19, which has a recording film laminated on a substrate made of this cyclic olefin random copolymer, has excellent long-term stability in terms of durability and recording properties.

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.

(Left below) In the present invention, the material of the recording layer 3 is not particularly limited, but for example, if 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 includes (i) at least one selected from 3d transition metals;
(i) 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 (i) at least one element selected from rare earths. Preferably, it consists of a species element.

(i) As a 3d transition metal, F e se o s
T s 1V, Cr, Mn, Nlz 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 P(, Pd1T
I, Z rSTa, Mo, Nb.

Although Hf and the like are used, Pt and Pd1Ti are preferred, and pt and/or Pd are particularly preferred.

(i) Examples of rare earth elements include Gd and Tb.

Dy, Ho, Er, Tm, Yb5Lu, La.

Ce, Pr, %NdsPm55m5Eu, etc. are used.

Among them, Gd, Tb, Dy, Ho, Nd, Sm.

Pr 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-8b alloy thin film, In-8b-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
It is 50 to 5,000 λ, preferably 100 to 2,000.

The metal layer 4 in the first information recording medium according to the present invention is
Based on the total number of atoms constituting the aluminum alloy, chromium 0.1 to 5 at% and hafnium 0.1 to 9.5 at%
It is formed from an aluminum alloy containing chromium and hafnium in a total content of 10 atomic % or less.

The content of chromium in this metal layer is 0.1
It is preferably in the range of ~5 at%, and particularly preferably in the range of 1 to 3 at%.

The content of hafnium is in the range of 0.1 to 9.5 at%, particularly preferably in the range of 1 to 5 at%.

Further, the total content of chromium and hafnium is preferably 10 atomic % or less. In the present invention, the content of chromium is 0.1 to 5 at%, and the V-containing hafnium silk is 0.1 to 5 at%.
By using an aluminum alloy with a total content of chromium and hafnium of 10 at% or less in the range of 9.5 at% as the metal layer, the metal layer and the information recording medium have excellent corrosion resistance, and the information storage It has the effect that the linear velocity dependence of the recording medium is small and the protective effect of the recording layer is excellent.

Further, the metal layer 4 in the second information recording medium according to the present invention
is based on the total number of atoms constituting the aluminum alloy, (i) 0.1 to 5 at% of chromium, and (i) 0.1 at.% of titanium.
~9.5 at.% and hafnium 0.1-9.5 at.%
It is formed from an aluminum alloy containing chromium, titanium, and hafnium whose total content is 10 atomic % or less.

Further, the metal layer 4 as described above is made of aluminum (AI),
In addition to chromium (Cr) and hafnium (If), a small amount of one or more other elements (metals) can also be included. Examples of such elements (metals) include silicon (S
i), tantalum (T1), copper (Ca), tungsten (W), zirconium (!+), manganese (Ma)
, vanadium (V), etc., and when such other elements (metals) are included, such other elements are usually contained in an amount of 5 at % or less, preferably 2 at % or less.

The thickness of the metal layer as described above is usually between 100 and 500 mm.
0, preferably 500 μm to 3000 λ, particularly preferably 700 λ to 2000 λ.

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. As a result, it is thought that the dependence of recording power on linear velocity becomes smaller.

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

The information recording medium according to the present invention is not limited to the configuration shown in FIG. 1, but for example, as shown in FIG. The recording layer 3 and the metal layer 4 may be stacked on top of each other. Further, as shown in FIG. 3, a first protective film 5 is laminated on the substrate 2, a recording layer 3 is laminated on top of the first protective film 5, and a second protective film 5 and a metal film 4 are further laminated in this order on top of the first protective film 5. Good too. As such a protective film (enhancement film) 5, for example, Si
It is preferably formed from N, SiNx (0<x<4/3)4AIN, Zn5e, ZnS, Si or CdS, but is not limited thereto.

The thickness of such a protective film is about 100 to 2,000 thick, preferably about 300 to 1,500 thick. Among these, St.
It is preferable to use N, SiNx4 (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 greater than that 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 has a gold scrap layer made of an aluminum alloy containing specific amounts of chromium and hafnium, or containing specific amounts of chromium, hafnium, and titanium. Therefore, it has excellent corrosion resistance, low linear velocity dependence of recording power, and excellent protection of the recording layer.

EXAMPLES 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
Hr, dut7 represents the recording power at which the second harmonic of the reproduced signal is minimum with respect to a 50% write signal, and the smaller the difference in the optimum recording power depending on the linear velocity, the smaller the linear velocity dependence.

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

Aluminum (AA')-chromium (C
A metal layer made of an aluminum-chromium-hafnium alloy with a thickness of 1000 pieces was produced by sputtering using a composite target of r)-hafnium (old).

The chromium and hafnium contents of the produced metal layer were each 2 atomic %.

This metal layer was immersed in a 10% by weight thorium chloride aqueous 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. In addition, the number of pinholes generated per unit area (5an x 5cm) of the metal layer after dipping was 50.
(49).

Example 2 On a substrate made of amorphous polyolefin, a protective film made of Si3N (film thickness Ion6) and PtTbFeCo
(Pt, oTb, , , Fe, , 5CO,) recording layer (film thickness: 500 mm) is sequentially laminated by sputtering method, and sputtering method is performed using a composite target of Ajl-Cr-Hf on this recording film. A metal layer made of an Al-Cr-Hf alloy with a thickness of 700 mm was laminated using the following steps. The Cr content in the Ar alloy (i!) constituting the obtained metal layer was 2 atomic %, and the Hf content was 2 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 information recording medium was evaluated by measuring the change in reflectance of the information recording medium. did.

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 3 Ethylene and 1.4.5.8-dimethanol-1,2,3,4
, 4, 5.8 or less abbreviated as DMON) (ethylene content measured by i3C-NMR analysis: 5
9 mol%, DMON content 41 mol%, intrinsic viscosity [η] measured in decalin at 135°C is 0.42d17g.

5j on a substrate with a softening temperature (TMA) of 154°C
A protective film made of 3N4 (thickness: 1100) and P j
A recording layer (thickness: 260 mm) made of IOT b 29 Fe ssCOs is sequentially laminated by sputtering, and an A layer with a thickness of 500 λ is deposited on this recording layer by sputtering using a composite target of Al-Cr-Hf.
Metal layers made of l-Cr-Hf alloy were laminated. The content of Cr in the A1 alloy (layer) constituting the obtained metal layer was 2 atomic %, and the content of Hf was 2 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 information recording medium was evaluated by measuring the change in reflectance of the information recording medium. did.

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.

The optimum recording power of this information recording medium at a linear velocity of 5.7 m/see is 3.6 mW, and the linear velocity L is 1.3 m/zc.
The optimum recording power was 5.3 mW.

Comparative Example 1 A metal layer made of an aluminum-chromium alloy with a thickness of 1000 mm was produced on a glass substrate by sputtering using an aluminum-chromium composite target.

The chromium content of the produced metal layer was 2 at.%.

This metal layer was immersed in a 10% by weight aqueous sodium chloride solution at a temperature of 60° C. for 4 hours.

Changes in reflectance and film state after 4 hours of immersion were measured.

The reflectance of the metal layer decreased by about 2% due to immersion.

Further, the number of pinholes generated per unit area of the metal layer film (5ao x 5an) was about 70.

Comparative Example 2 A composite target consisting of an aluminum-chromium alloy with a different alloy composition from Comparative Example 1 was used with a chromium content of 4 at%.
A metal layer was produced in the same manner as in Comparative Example 1, except that the metal layer was produced.

This metal layer was immersed in a sodium chloride aqueous solution in the same manner as in Comparative Example 1, and changes in reflectance and film state after immersion were measured.

The reflectance of the metal layer did not change before and after immersion in the sodium chloride aqueous solution, and the number of pinholes generated per unit area (5 an x 5 an) of the reflective metal film after immersion was about 70.

[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 FIGS. 2 and 3 are schematic cross-sectional views of information recording media according to other embodiments 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 0.1 to 5 at.% of chromium based on the total number of atoms constituting the aluminum alloy. An information recording medium comprising an aluminum alloy containing 0.1 to 9.5 at. % of hafnium and having a total content of chromium and hafnium of 10 at. % or less. 2) An information recording medium having a recording layer and a metal layer on a substrate, in which the metal layer contains (i) 0.1 to 5 at% of chromium, based on the total number of atoms constituting the aluminum alloy;
From an aluminum alloy containing ii) 0.1 to 9.5 atomic % titanium and (iii) 0.1 to 9.5 atomic % hafnium, and the total content of chromium, titanium, and hafnium is 10 atomic % or less An information recording medium characterized by: