JPH02223477A - Optical recording medium - Google Patents

Abstract

PURPOSE:To enhance an adhesion between a recording film and a substrate by a method wherein an optical recording medium is formed by providing the recording film containing Te as a main component, Cr, C, and H on the substrate made of a cyclic olefin random copolymer. CONSTITUTION:By applying a magnetron sputtering method to Te and Cr as separate targets in a mixed gas of an organic gas containing C and H and an Ar gas, a recording layer 12 made of a Te-Cr alloy thin film containing C and H is formed on a substrate 11, whereby an optical recording medium 10 is produced. As the substrate 11, a cyclic olefin random copolymer shown by a formula I is used. In the formula I, (n) represents 0 or a positive integer, R<1> - R<12> are H, halogen or hydrocarbon, and R<9> - R<12> may bond with each other to form a monocyclic or polycyclic group, which may have double bonds.

Description

TECHNICAL FIELD OF THE INVENTION The present invention relates to an optical recording medium in which information is recorded by forming pits in a recording film on a substrate by irradiation with an energy beam such as light or heat.

Technical Background of the Invention There are two types of optical recording media: those in which physically changed parts such as holes or recesses are formed in a part of the recording film by irradiation with an energy beam, and those in which a part of the recording film has optical properties ( There is also a method in which an optical characteristic changing section is formed by changing the refractive index, reflectance, etc.).

As a recording film for any type of optical recording medium, a recording film whose main component is a low-melting point metal such as tellurium (Te) has been known (Japanese Patent Application Laid-open No. 71195/1983,
(Japanese Unexamined Patent Publication No. 58-9234). Te film, which is typical as a low-melting point metal film, can form desired physical change parts or optical property change parts (hereinafter collectively referred to as "pit J") with very low energy, making it extremely useful as a high-sensitivity material. Here, sensitivity is defined as the energy required to form pits per unit area (mJ/ad).

As described above, recording films containing Te as a main component are known, but an optical recording medium in which these recording films are laminated on a normal substrate made of polycarbonate resin,
There is a problem that the recording sensitivity is not sufficient, and there is a desire for an optical recording medium with further improved recording sensitivity.

Furthermore, optical recording media in which a recording film containing Te as a main component as described above is laminated on a normal substrate, such as a substrate made of polycarbonate resin, have insufficient adhesion between the substrate and the recording film. Therefore, in order to improve the adhesion between the substrate and the recording film, a step of plasma-treating the surface of the polycarbonate resin substrate is sometimes necessary.

The present inventors conducted intensive research to increase the recording sensitivity of the optical recording medium as described above and also to improve the adhesion between the substrate and the recording film, and found that a random combination of ethylene and cyclic olefin having a specific structure was used as the substrate. The author of this book discovered that by using a copolymer and laminating a specific recording film on the substrate as described above, an optical recording medium with excellent recording sensitivity and excellent adhesion between the substrate and the recording film could be obtained. The invention was completed.

In order to improve the oxidation resistance of a recording film containing Te as a main component, studies have also been conducted from the viewpoint of the composition of the recording film. For example, in Japanese Patent Publication No. 59-33320, A Te film containing Cr has been proposed, and JP-A-59-63038 proposes a Te film containing Cr. However, none of the recording films containing Te as a main component proposed in the above-mentioned publications have sufficient oxidation resistance.

Purpose of the Invention The present invention aims to solve the problems associated with the prior art as described above, and provides an optical recording medium with excellent recording sensitivity and excellent adhesion between the substrate and the optical recording film. It is intended to.

Summary of the Invention The optical recording medium according to the present invention consists of a substrate and a recording film formed on the substrate.By irradiating the recording film with an energy beam, pits are formed in the recording film and information is stored. In the optical recording medium for recording, the recording film is a thin film containing Te as a main component and Cr, C, and H, and the substrate is composed of ethylene and a cyclic olefin represented by the following general formula [I]. It is characterized by being formed from a cyclic olefin random copolymer consisting of a copolymer of

(In formula [I], n is 0 or a positive integer,
R1 to R12 each represent a hydrogen atom, a norogen atom, or a hydrocarbon group, and R9 to R12 may be bonded to each other to form a monocyclic or polycyclic group, and The group may have a double bond, and R9 and RlO or R11 and R12 may form an alkylidene group).

In such a cyclic olefin random copolymer, the cyclic olefin component forms a structure represented by the general formula [■].

(In formula [1], n is 0 or a positive integer,
R to R12 each represent a hydrogen atom, a halogen atom, or a hydrocarbon group, and R-R12 may be bonded to each other to form a monocyclic or polycyclic group,
The monocyclic or polycyclic group may have a double bond, and R and R or Rli and R12 may form an alkylidene group).

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

The optical recording medium 10 according to the present invention has a structure in which an optical recording film 12 is laminated on a substrate 11, as shown in FIG.

Further, in the optical recording medium 10 according to the present invention, the optical recording films 12 of the two recording media 10 face each other with an outer circumferential spacer interposed at the outer circumference and an inner circumferential spacer interposed at the inner circumference. In this way, they may be bonded together to form an optical recording medium with an air sandwich structure.

At this time, the spacer and the optical recording medium may be joined by ultrasonic welding or by using an adhesive such as a hot melt adhesive.

Substrate In the optical recording medium according to the present invention, the substrate 11 as described above is made of a copolymer of ethylene and a cyclic olefin represented by the following general formula [I], and has a copolymer of ethylene and a cyclic olefin represented by the following general formula [I]. Intrinsic viscosity [η] is 0.05 to 10 dA! /g of a cyclic olefin random copolymer.

A random copolymer will be explained.

To explain in more detail about the cyclic olefin represented by the above general formula [I], in addition to being represented by the above formula [I], the cyclic olefin represented by the above general formula [11] is also represented by the following formula [I-a]. It can also be expressed.

(In formula [I], n is 0 or a positive integer,
R1 to R12 each represent a hydrogen atom, a halogen atom, or a hydrocarbon group, and R9 to R12 may be bonded to each other to form a monocyclic or polycyclic group, and the monocyclic or polycyclic group may have a double bond, and R and R or R11 and R12 may form an alkylidene group).

The cyclic olefin random copolymer as described above preferably has a softening temperature (TMA) of 70° C. or higher. Hereinafter, such a cyclic olefin type having a softening temperature (TMA) of 70°C or higher, provided that in the above [I-a], n is O or 1, m is 0 or a positive integer, and R1-R18 each independently represents an atom or group selected from the group consisting of a hydrogen atom, a halogen atom, and a hydrocarbon group.

R15 to R18 may be bonded to each other to form a monocyclic or polycyclic group, and the monocyclic or polycyclic group may have a double bond.

Furthermore, R15 and R16 or R17 and R18 may form an alkylidene group.

In such a cyclic olefin random copolymer, the cyclic olefin component forms a structure represented by the general formula [■].

(may form an alkylidene group).

Incidentally, when the cyclic olefin is represented by [I-a] as described above, in the cyclic olefin-based random copolymer, the cyclic olefin component is represented by the formula [II-a] shown below.
a].

(In formula [11], n is O or a positive integer, R to R12 each represent a hydrogen atom, a halogen atom, or a hydrocarbon group, and R9 to R12 are bonded to each other to form a monocyclic or polycyclic group. The monocyclic or polycyclic group may have a double bond, and R and R or R11 and R12 may be 1, but the above [H -a], n is 0 or 1, m is O or a positive integer, and R1 to R18 are each independently an atom or group selected from the group consisting of a hydrogen atom, a halogen atom, and a hydrocarbon group. It's displayed.

R15 to R18 may be bonded to each other to form a monocyclic or polycyclic group, and the monocyclic or polycyclic group may have a double bond.

Furthermore, R15 and R16 or RI7 and RIll may form an alkylidene group.

The cyclic olefin that is a component of the above-mentioned cyclic olefin-based random copolymer is at least one cyclic olefin selected from the group consisting of unsaturated monomers represented by the general formula [II].

The cyclic olefin represented by II in the general formula can be easily produced by condensing a cyclopentadiene and a corresponding olefin in a Diels-Alder reaction.

As the cyclic olefin represented by the general formula [II, specifically, the compounds described below, or 2.5 7.1
0 is tetracyclo[4,4,0,1,1]-]3-dodecene14,5.8-dimethano-1,2,3,4,4a,
5.8.8a ~ octahydronaphthalene), in addition to 2
-Methyl-1,4,5,8 dimethanol-1,2,3,4,
4a, 5.8.8a-octahydronaphthalene, 2-
Published by ethyl-1,4,5,8-dimethano, 2,344m,
5.8.8a-Octahydronaphthalene, 2-propyl-1458-dimethano-1,2,3,4,4a, 5
．． 8.8a-octahydronaphthalene, 2-hexyl-
1,4,5,8-dimethanol 1.2.3.4. Ia,
5.8.8a-Octahydronaphthalene, 2,3-dimethyl-1,4,5,8-dimethano-I2344a, 5
．． 8.8a-octahydronaphthalene, 2-methyl-3
Ethyl-1,4,5,8-dimethano-1,2,3,4,
4a 58 Ha myophthahydronaphthalene 2-chloro-1458 dimethanol-1,2,3,4,4a, 5.8
．． 8a-octahydronaphthalene, 2-bromo-1,4
, 5,8-dimethanol 2344a, 5.8.8a-octahydronaphthalene, 2-fluoro L 4.5.8-
Dimethano-1,2,3,4,4a, 5.8.8a-octahydronaphthalene, 2,3-dichloro-1,45,
8-dimethano-1,2,3,4,4a, 5.8.8a
-octahydronaphthalene, 2-cyclohexyl-],
4.5.8-dimethano-123,4,4a, 5.8
．． 8a-octahydronaphthalene, 2-n-butyl-1
,4,5,8-dimethano-1,2,3,4,4a, 5
88a-octahydronaphthalene, 2-isobutyl-1
,4,5,8-dimethano-1,2,3,4,4B, 5
．． Octahydronaphthalenes such as 8.8a-octahydronaphthalene can be exemplified.

Furthermore, examples of the cyclic olefin [II represented by the formula include the compounds described below.

(Left below) Specifically, the cyclic olefin represented by the above formula [I] used in the present invention includes bicyclo[2,2,11hept-2-ene-derived tetracyclo[4, 4,0,12,S,17,1”
]-]3-dodecene induced imitation xacyclo[6,6,1,136,1111,13,
Q2.7. Q9. +4] 4-heptadensene-derived vermilion octacyclo[8,8,0,12,'', 1', 7, 1st y+e, 1-fold 3.l6Q3.e, QI217]-5-tococene-derived 4-pentacyclo[6, 6,1,13・6.
02・7.09・14]-4-Hexadecene derivative Heptacyclo-5-icosene derivative This heptacyclo 5-heneicosene derivative, tricyclo[4,3,0,12,6-3-decene derivative 4-tricyclo[4, 3,0,12,6]-3-undecene derivative pentacyclo[6,5,1,13・6,02・? ,Q9
．． +3] -4-pentadecene induction book pentacyclopentadecadiene induction bill pentacyclo[
4,7,0,12・5.08・13.19・+2]-3
- Pen l Tadecene derivative book Pentacyclo [7, g, QJ3. e, Q2.7. l+1
1. +7. Qo, 16112.151-4-eicosene derivatization and nonacyclo[9,10,1,1,4,7,03・8,0
2・Ill, Q12・21113・2G, Q14・19
．． 116·Il+] 5-bentacocene derivatives.

Specific examples of such compounds are shown below.

Bicyclo [2, 2, 11 conductor; hept enticement Sl CH.

hmm 5.1 Leaf dimethyltetra 9-ethyl-11,12-dime 9-isobutyl 11, 12 5,8.9.10-tetramethy Yu1 2,7.9-) Remethylte CH.

-) -O 8-Methyltetrasif 8-ethyltetrasif 18] 3-dodecenehexyltetrasif] + 11 ] -3 Dodecene 8-methylethyltedodecene-3-dodecene 1-3-dodecene.I f+ ] - 3 Dodesenyu 3. 12 5.17.11I 3-dodecene-dodecene, 12 6.17.111]-3-dodecene 5+ 17・' e]-3-F Tese:/father 5.17.18 3-dodecene 7.10 ] dodecene 3-dodecene, +e coco-dodecene, 12.6, 17.111 co-3 dodecene i da [4, 4, 0, 12・5.17・Il! ] 3-Dodecene [4,4,0,12 17・+9] 3-Dodecene [4,4,0,12・5.17 Item 1-3 Dodecene-Dodecene 8-Impropylidene 14] 4-Hebutade Tetracyclo[4,4,0,125,17,11
1-3 Dodecene derivative; (blank below) Heptadecene ag' 3.111. Q3.8. Q12 17] 5-tococene derivative; +s, (12', 7.Q* +4] Hexacyclo[6,6,1,13・6.1111 such as 4-heptadecene
・I 3 , Q2 ・7, 09.14 Co-4-heptadecene derivatives; Tococene lfl, 113 + 6, Q3 8.01 2.17]-5 Pentacyclo[6 such as tococene 15-ethyl octashif + vl-5-tococene ,6,1,13,6,02? ,
Q9.14] -4- and other octacyclo [8, 8, 0, 12, 9.14, 7
, 1st Il+, 11 hexadecene derivative.

tricyclo[4,3,0,12.5 codecene derivatives such as heptacyclo[8,7,0; heptacyclo-5-icosene derivatives such as common 4,4,0,12 5]-3 Undecene derivatives 3/ Pentacyclo[47,Q, 12. s, Qll, +3,1912] -3-pentadecene derivatives; 14,15 dimethyl pen +6,112 15] pentacyclo[6,5,1,13,6. O2?
, Q9, l3],,-]4. -Pentadecene derivative; 7. lI[1 17,0th 16.11 15] Hebutacyclo[7I8. Q, 13.6. Q2.7. lI9. +7. Q
10,112 15] -4-eicosene derivatives; diene compounds such as 21, ll3.28. Qld D9,1 5.18] 5-bentacocene 3.211. QIA, +9. ll5. Ie] nonacyclo[jJ IQ, l, 14. such as 5-hentacocene. v, Q
3. ll, Q2. Ill, Q10.21, 113.29
．． QIA, +9,116.111] 5-bentacocene derivative; (blank below) Shio and Meko's cyclic olefin-based random copolymer contains ethylene and the cyclic olefin as essential components, as described above. 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 an amount less than equimolar to the ethylene component unit in the random copolymer to be produced. -α-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, and l-eicosene For example,

In the above-mentioned cyclic olefin random copolymer having a softening point (TMA) of 70°C or higher, the repeating unit (a) derived from ethylene is in the range of 40 to 85 mol%, preferably 50 to 75 mol%. The repeating unit (b) derived from the cyclic olefin is 15 to
The repeating unit (a) derived from ethylene and the repeating unit (b) derived from the cyclic olefin are present in an amount of 60 mol%, preferably 25 to 50 mol%,
They are randomly arranged in a substantially linear manner. Note that the ethylene composition and cyclic olefin composition were measured by 13C-NMR. The fact that this cyclic olefin random copolymer is substantially linear and does not have a gel-like crosslinked structure can be confirmed by completely dissolving the copolymer in decalin at 135°C.

135 of such a cyclic olefin random copolymer
The intrinsic viscosity [η] measured in decalin at ℃ is 0.05
~10 dA'/g, preferably 0.08-5 dj! /g
within the range of

In addition, the softening temperature (TMA) of the cyclic olefin random copolymer was measured using a thermal mechanical analyzer.
is in the range of 70°C or higher, preferably 90 to 250°C, more preferably 100 to 200°C. The softening temperature (TMA) is Thermomecha manufactured by DuPont.
The thermal deformation behavior of a 1 mm thick sheet was measured using nical Analyse+. That is, a quartz needle was placed on the sheet, a load of 49 g was applied, the temperature was raised at a rate of 5° C./min, and the temperature at which the needle penetrated 0.635 mm was defined as TMA. Further, it is desirable that the glass transition temperature (Tg) of the cyclic olefin random copolymer is generally in the range of 50 to 230°C, preferably 70 to 210°C.

The degree of crystallinity of this cyclic olefin random copolymer measured by X-ray diffraction is in the range of 0 to 10%, preferably 0 to 7%, particularly preferably 0 to 5%.

The above-mentioned cyclic olefin copolymer constituting the substrate in the present invention is disclosed in JP-A-60-168708 and JP-A-6
1-120816, JP-A-61-115912, JP-A-61-115916, and Japanese Patent Application JP-A-61-115916.
! Publication No. 15905, Japanese Patent Application No. 1988-95906,
JP-A-61-271308, JP-A-61-272
It can be produced by appropriately selecting conditions according to the method proposed by the applicant in Publication No. 216 and the like.

In addition, as a resin forming the substrate, a cyclic olefin random copolymer as described above and a resin represented by the following formula [Ir[] formed by ring-opening polymerization of a cyclic olefin represented by the above formula [I] may be used. A repeating unit as shown in the following formula [1v] formed by hydrogenating a repeating unit represented by the above formula [III] may also be included. A polymer or copolymer containing may also be included.

However, in the above formulas [m] and [IV], n and R-R12 have the same meanings as n and R to R12 in the cyclic olefin shown in the above formula [I].

In addition, the above cyclic olefin copolymer may include, if necessary,
Heat-resistant stabilizers, weather-resistant stabilizers, antistatic agents, slip agents, anti-blocking agents, anti-fog agents, lubricants, dyes, pigments, natural oils, synthetic oils, waxes, etc. can be blended in appropriate amounts. It is. For example, specific stabilizers that may be added as optional ingredients include tetrakis[methylene-3(3,5-di-t-butyl-4-hydroxyphenyl)propionate comethane, β-(3,5-di-t-butyl-4-hydroxyphenyl)propionate comethane, (
-butyl-4hydroxyphenyl) propionic acid alkyl ester (alkyl esters having 18 or less carbon atoms are particularly preferred), 2,2'-oxamidobis[ethyl-3(
Phenolic antioxidants such as 3,5-di-t-butyl-4-hydroxyphenyl) propionate, fatty acid metal salts such as zinc stearate, calcium stearate, and calcium 12-hydroxystearate, glycerin monostearate, glycerin monolaurate , polyhydric alcohol fatty acid esters such as glycerin distearate, pentaerythritol monostearate, pentaerythritol distearate, and pentaerythritol tristearate. These may be blended alone or in combination, such as tetrakis[methylene-3(3,5-di-t-butyl-4-hydroxyphenyl)propionate comethane, zinc stearate, and glycerin]. Examples include combinations with monostearate.

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

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

Such a phenolic antioxidant is used in an amount of 0.0 parts by weight based on 100 parts by weight of the cyclic olefin random copolymer composition.
It is used in an amount of 1 to 10 parts by weight, preferably 0.05 to 3 parts by weight, more preferably 0.1 to 1 part by weight, and the fatty acid ester of polyhydric alcohol is used in an amount of 0.01 parts by weight per 100 parts by weight of the composition. It is used in an amount of ~10 parts by weight, preferably 0.05 to 3 parts by weight.

In the optical recording medium according to the present invention, the above-mentioned cyclic olefin random copolymer is used as the substrate 11, and although the reason for this optical recording medium is not clear,
It has superior recording sensitivity compared to optical recording media using polycarbonate, poly(meth)acrylate, etc. as a substrate. Further, the substrate 11 made of the cyclic olefin random copolymer and the recording film 12 have excellent adhesion, and therefore the recording film has excellent long-term stability and oxidation of the recording film is effectively prevented. Therefore, an optical recording medium in which a recording film 12 is laminated on a substrate 11 made of this cyclic olefin random copolymer has excellent recording sensitivity, durability, and long-term stability. Further, the optical recording medium 10 according to the present invention is free from warpage and cracks.

Recording Film The recording film 12 as described above used in the present invention is a thin film containing Te as a main component and at least Cr, C, and H, and may also contain low melting point elements other than Te or other components. Te that can be included in the recording film 12
Elements other than TiSMnXN i, Z r,
Nbz Ta, All.

Pt, SmXB15 In5Se, Pb, Co.

Examples include Si, Sb, Ge, Ag, Pd, Sn, and Zn.

The content ratio of Cr contained in such a recording film 12 is 0.1 to 40 atomic %, preferably 0.5 to 10 atomic %, particularly preferably 1 atomic %, based on the total number of atoms contained in the recording film.
-4 atomic %, or the content ratio of Cr to the total number of Te and Cr atoms in the recording film is 0.0.
It is preferably in the range of 1 to 40 atom %, preferably 0.5 to 10 atom %, particularly preferably 1 to 4 atom %.

This is because by including Cr in such a range, although the oxidation resistance of the recording film 12 is improved, the recording sensitivity does not decrease, and in some cases, the recording film density can be improved.

Further, from the viewpoint of improving the lifetime of the recording film and recording sensitivity, the content of C in the recording film 12 is less than 40 at%, preferably 3 to 20 at%, or less than 40 at%, preferably 3 to 20 at%, based on the number of atoms in the entire recording film. 40 for the total number of atoms of Te5Cr and C in
It is desirable that it is less than atomic %, preferably 3 to 20 atomic %. By containing C in such a range,
It becomes possible to improve recording sensitivity and recording margin.

Further, the content of H in the recording film 12 is desirably 1 to 40 atomic %, preferably 3 to 25 atomic %, based on the entire recording film 12 from the viewpoint of life span and the like. The content of each element contained in the recording film 12 is determined by ICP emission spectrometry (inductively coupled plasma emission spectrometry) for metal elements (such as TeSCt).
and X-ray photoelectron spectroscopy (ESC) for C.
A) and H are measured by organic elemental analysis.

To write information on the recording film 12 having the above composition, the recording film 12 is irradiated with an energy beam such as a laser beam that is modulated (on/off) depending on the information to be recorded. A pit may be formed in the irradiated portion. This pit may be a physically changed part such as a hole or a recess, or it may be an optical property changed part where optical properties such as refractive index or reflectance are changed.

The thickness of the recording film 12 needs to be thick enough to obtain sufficient light reflectance and thin enough not to impair sensitivity. Specifically, when forming a physically changed part such as a hole in the recording film 12, the thickness of the recording film is 100 to 1.
[mu]m is preferably about 100 to 5,000 people, more preferably about 150 to 700 people. Further, when forming an optical characteristic changing portion such as reflectance or refractive index on the recording film 12, the thickness of the recording film is 100 μm to 1 μm, preferably 100 μm.
~5000 people, more preferably about 200~2000 people.

In order to form such a recording film 12 on the surface of the substrate 11, it can be performed, for example, as follows.

First, using Te and Cr as separate targets or a Te-Cr alloy as a target, in a mixed gas of an organic gas containing C and H, such as CH4 or C2H2 gas, and Ar gas, by magnetron sputtering method. On the substrate 11, Te- containing C and H
A recording film 12 made of a Cr alloy thin film is formed. It is also possible to form the recording film 12 made of a Te--Cr alloy thin film containing C and H on the substrate by forming CH4 and TeCr alloy vapor into plasma without using the sputtering method. Further, a similar recording film 12 can also be formed by vapor phase epitaxy or plasma vapor phase epitaxy. Still another method is T e 1Cr N CS
Some or all of the Fl atoms may be ionized and deposited on the substrate in the form of a beam.

The atomic ratio of Te and Cr in the recording film 12 made of such a Te-Cr alloy thin film containing C and H is T
When sputtering e and Cr simultaneously, it can be freely controlled by the respective applied voltages, and if an alloy target is used, by the alloy composition. Further, the content of C and H in the recording film 12 made of a Te-Cr alloy thin film is CH
It can be freely controlled by the mixing ratio of 4 and Ar, the applied voltage, or the gas pressure during sputtering. In this case, the H content at which the film is most chemically stable is determined by the C content. Here, the H content can be arbitrarily selected as long as it is not so large that hydrogen gas (H2) is generated in the film. Furthermore, since the film thickness is proportional to the sputtering time,
Can be controlled freely.

Te-containing C and H formed in this way
The optical properties such as reflectance or extinction coefficient of the recording film 12 made of a Cr alloy thin film vary depending on the C and H contents. Thickness is determined.

The recording film 12 formed under the above conditions has significantly improved oxidation resistance and recording sensitivity compared to a film formed from a low melting point metal such as Te.

For example, in a Te recording film containing Cr, C, and H, the change in reflectance when stored at high temperature and high humidity for a long period of time is smaller as the Cr content increases, compared to a recording film containing only Te. It was confirmed through experiments that the oxidation resistance of the recording film according to the present invention was improved.

Furthermore, it has been confirmed through experiments that, for example, the recording film according to the present invention has a relatively small recording energy output and improved recording sensitivity.

Furthermore, as shown in FIG. 2, the optical recording medium according to the present invention (curve A in the figure) is superior to the conventional optical recording medium having a Te film containing C and H (curve B in the figure). It was confirmed that the C/N ratio hardly changes even with slight fluctuations in the recording energy output, and that the recording margin is wide.

Furthermore, as shown in FIG. 3, the optical recording medium according to the present invention (curve A in the figure) is different from the conventional Te
It was also confirmed that, compared to an optical recording medium having a film (curve B in the figure), there was almost no change in reflectance over time and the durability was improved. This is also clear from Table 2, which will be described later.

Further, in the present invention, as described above, the recording film 1 is placed on the substrate 11.
After forming the recording film 2, the recording film 12 or the recording film 12 and the substrate 11 can be heat-treated in an inert gas, reducing gas, or gas atmosphere containing oxygen, if necessary. The heat treatment temperature needs to be below the melting point of Te contained in the recording film, preferably 70 to 300
℃, especially preferably in the temperature range of 90 to 150℃. Further, the heat treatment time is preferably 5 seconds or more.

In this way, by heat-treating the recording film 12 or the recording film 12 and the substrate 11 after forming the recording film 12 on the substrate 11, the recording sensitivity of the recording film is improved and the recording margin is widened. This is thought to be because the recording film is crystallized to some extent by the heat treatment.

Note that the present invention is not limited to the embodiment shown in FIG. 1, and can be variously modified within the scope of the present invention.

For example, as shown in FIG.
A base layer 13 may be laminated between the two.

As the base layer 13, for example, magnesium fluoride (M
fluoride film consisting of silicon oxide (SI0
Silicon compound film made of 2.5IO) or silicon nitride (SJN4), Ti, Ni5Cr, AI or N
Metal thin films made of i-Cr etc., thin films of fluorine-substituted hydrocarbon compounds and/or their polymers such as polytetrafluoroethylene (PTFE) thin films, Cr-CH thin films (films containing Cr, C and H), etc. are used. It will be done. The thickness of the base layer 13 varies depending on its material, but
Generally 10-1000 people, preferably 50-500 people. By setting the film thickness in this manner, transparency can be maintained and various characteristics as the base layer 13 can be exhibited.

In order to form such an underlayer 13 on the surface of the substrate 11, similarly to the case of forming the recording layer 12, magnetron sputtering method, vapor phase epitaxy method, plasma vapor phase epitaxy method, vapor deposition method, spin code method, etc. This can be done by applying.

If such an underlayer 13 is provided between the substrate 11 and the recording film 12, the recording sensitivity will be further improved and, in some cases, the recording margin will be further expanded.

Further, an optical recording medium formed by laminating the above-described recording film 12 on the above-described substrate 11 has particularly excellent recording sensitivity and, in some cases, even wider recording margin.

Further, according to the present invention, a surface layer may be formed on the surface of the recording film 12 in the optical recording medium 10 shown in FIG. 1 or 4. The material forming the surface layer is
Elements of the recording film, oxides such as 5iSTi, nitrides, metals, etc. are used. The thickness of the surface layer varies depending on the material, but is 5 to 100 layers, preferably 10 to 50 layers.

Effects of the Invention The optical recording medium according to the present invention is formed by laminating a recording film containing Te as a main component and further containing Cr, C and H on a substrate made of a random copolymer of ethylene and cyclic olefin. Because of its structure, it has excellent effects such as excellent recording sensitivity, excellent adhesion between the substrate and recording film, and excellent oxidation resistance.

[Examples] The present invention will be described below based on more specific examples, but the present invention is not limited to these examples.

Example 1 After evacuating the vacuum container, Ar gas, CHt, and gas were introduced, and the internal pressure was set to 6 x 10' Torr (Ar
/CH4=9/1: gas flow rate ratio). Next, T
Simultaneous sputtering was performed using e and Cr as targets. At that time, by controlling the voltage applied to each target and the sputtering time, T e g7Cr 2
A recording film with a thickness of 240 and a composition of C4Hv was prepared using ethylene and tetracyclo[44,012・5.17・101−
3-dodecene (structural formula = ω, abbreviated as DMON below)
A non-quality copolymer (ethylene content 59 mol%, DMON content 41 mol%,
Intrinsic viscosity [η] measured in decalin at 5°C is 0.42d
l/g, softening temperature (TMA) 154 °C) on an optical disk substrate (hereinafter referred to as PO substrate),
An optical recording medium was obtained.

Example 2 A recording film of Te s7Cr 2 Ci, H7 was formed on a PO substrate in the same manner as in Example 1 except that the thickness of the recording film was 290.

Examples 3 and 4 Examples 1 and 2 were each treated at a temperature of 100°C under a N2 atmosphere.
Heat treatment was performed for 0 minutes.

Example 5 Using a Te 97 Cr 3 alloy target and setting the gas flow rate ratio to Ar/CH4 = 9/1, a Te Cr CH film with a film thickness of 230 people was deposited on a PO substrate in the same manner as in Example 1. The film was deposited on

Example 6 After evacuating the vacuum container, Ar gas, CHi, and gas were introduced to make the internal pressure 6 x 10'Tor+ (Ar/
CH4=9/togas flow rate ratio). Next, simultaneous sputtering was performed using Te and Cr as targets. At that time, by controlling the voltage applied to each target and the sputtering time, the atomic ratio of Te, Cr and C in the recording film can be expressed by the following formula, (Te Cr 98.8 1.2 )96C4 Te.

A recording film containing Cr, C and H was produced with a film thickness of 240 mm.
A film was formed on a substrate to obtain an optical recording medium.

Example 7 The atomic ratio of Te1Cr and C was determined by the following formula, (T
A recording film containing Te, Cr5C and H represented by e98Cr2)96C4 was formed on a PO substrate.

Example 8 The atomic ratio of Te, Cr and C was determined by the following formula, (T
e Cr 96.8 3.2 ) 96°47 Te, Cr
A recording film containing , C and H was formed on a PO substrate.

Example 9 Same as Example 6 except that the film thickness was 230 people,
The atomic ratio of Te1Cr and C is as follows, (Te92C
r8) Te, Cr expressed as 98C2.

A recording film containing C and H was formed on a PO substrate.

Example 10 The atomic ratio of Te5Cr and C was determined by the following formula, (Te
Cr 97.5 2.5 ) Te represented by 96C4.

A recording film containing Cr, C and H was formed on a PO substrate.

Example 11 The atomic ratio of Te, Cr and C was determined by the following formula, ( Te
Cr 95.1 4.9 ) Te represented by 98C2.

A recording film containing Cr, C and H was formed on a PO substrate.

Examples 12-17 The optical recording media of Examples 6-11 were each subjected to heat treatment at a temperature of 100'C for 20 minutes under an N2 atmosphere.

[Test results] (1) Rotate the disk at 1800 rpm to 3.7MH
The recording characteristics were examined by irradiating laser light at a frequency of 2.

Here, C/Nmax is the C when changing the laser power.
/N ratio maximum value. Recording sensitivity is C/N max
The minimum value of the laser power that satisfies X O,9 < C/N, and the margin represents the range of laser power that satisfies C/N > C/NmgxX0.9.

The results are shown in Table 1.

Table 1 (2) The reflectance R after being left for 500 hours in an environment with a temperature of 70° C. and a relative humidity of 85% is measured by making a cut in the shape of a surface of the original reflectance.

Made by Chiban on cellophane tape) worth it.

Evaluation ■ Peeling evaluation table 3 using immediately after film formation [Evaluation of adhesion between substrate and optical recording film] The adhesion between the substrate and optical recording film of the optical recording medium of Example 3 was evaluated by the following method. Ta.

The results are shown in Table 3.

Adhesion Test Baseline Test (Its K5400) On the recording film of the sample, 11 orthogonal parallel lines are drawn at 1 mm intervals using a cutter knife. Base $1: 100 so that there are 100 squares in 1d
/+00 indicates that out of 100 squares, there are 100 squares that did not peel off.

[Brief explanation of the drawing]

FIG. 1 is a schematic cross-sectional view of an optical recording medium according to an embodiment of the present invention, and FIGS. 2 and 3 are graphs showing differences in function and effect between the optical recording medium according to the present invention and a conventional optical recording medium. FIG. 4 is a schematic cross-sectional view of an optical recording medium according to another embodiment of the present invention. 10... Optical recording medium 11... Substrate 12...
・Recording film 13... Underlayer diagram

Claims (1)

[Scope of Claims] 1) Consisting of a substrate and a recording film formed on the substrate, the recording film is irradiated with an energy beam to form pits in the recording film and record information. In the optical recording medium, the recording film is a thin film containing Te as a main component and Cr, C, and H; An optical recording medium characterized by being formed from a cyclic olefin random copolymer consisting of: ▲ Contains mathematical formulas, chemical formulas, tables, etc. ▼...[I] (In formula [I], n is 0 or a positive integer, R^1 to R^1^2 each represent a hydrogen atom, a halogen atom, or a hydrocarbon group, and R^9 to R^1^2 are bonded to each other to form a monocyclic or polycyclic ring. may form a group, and the monocyclic or polycyclic group may have a double bond, and R^9 and R^1^0, or R^1^1 and R^
1^2 may form an alkylidene group).