JPS61123592A - Information recording medium - Google Patents

Abstract

PURPOSE:To obtain subject recording medium with increased information density and improved recording sensibility by providing an intermediate layer which contains polymeric substance of a specified photopolymerizable monomer be tween a substrate and a recording layer which enables writing and reading of informations. CONSTITUTION:On a surface of substrate of a glass plate etc. an undercoat layer is provided directly, or as required, and on the top of the layer an interme diate layer which contains polymeric substance of photopolymerizable monomer consisting of (meta) acrylic ester compound as expressed in the formulas I, II and/or III listed below is provided, and further, on its top a recording layer is provided, resulting in obtaining subject information recording medium: Formu la I (R<1>, R<2> indicate H, CH3; X indicates -C2H4O-, -C3H6O-; y indicates that when x is -C2H4O-, it is 6-12, and when it is C3H6O-, it is 3-12). Formula II (R<3>, R<4>, R<5> indicate H, CH3; 0<=i<=9; 0<=j<=k<=9; i+j+k>=1) Formula III (R<6>, R<7>, R<8> indicate H, CH3; 0<=l<=9; 0<=m<=9; 0<=n<=0; l+m+n>=1).

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of the Invention] The present invention relates to an information recording medium on which information can be written and/or read using a high energy density laser beam.

[Technical Background of the Invention and Prior Art] In recent years, information recording media that use high energy density beams such as laser light have been developed and put into practical use. This information storage medium is called an optical disk, and can be used as a video disk, an audio disk, a large-capacity still image file, and a large-capacity computer disk memory.

The basic structure of optical discs is plastic.

It has a disk-shaped transparent substrate made of glass or the like, and a recording layer made of a metal or semimetal such as Bi, Sn, In, Te, etc. placed thereon.

Information is written on an optical disk by, for example, irradiating the optical disk with a laser beam.
The irradiated portion of the recording layer absorbs the light and locally increases in temperature, resulting in a physical or chemical change that changes its optical properties, thereby recording information. Reading information from an optical disc is also carried out, for example, by irradiating the optical disc with a laser beam, and by detecting reflected or transmitted light according to changes in the optical properties of the recording layer. Information is played.

Recently, a disk structure for protecting the recording layer has been constructed from two disk-shaped substrates, with a recording layer provided on at least one of the substrates, and the two substrates are arranged so that the recording layer is on the inside. An air sandwich structure has been proposed in which a ring-shaped inner spacer and a ring-shaped outer spacer are joined together to form a closed space.

In optical discs with such a structure, the recording layer is not in direct contact with the outside air, and information is recorded and reproduced using laser light that passes through the substrate, so the recording layer is generally susceptible to physical or chemical damage. Or, dust will not adhere to the surface and interfere with recording and reproducing information.

Information recording media are highly useful in various fields as described above, but it is desired that their recording sensitivity be as high as possible.

Conventionally, in order to improve recording sensitivity, polymethyl methacrylate,
A well-known technique is to reduce the loss of thermal energy from laser beam irradiation due to thermal conduction from the recording layer to the substrate, etc. by providing an intermediate layer (insulating layer) made of thermoplastic resin such as nitrocellulose. .

Further, for the purpose of increasing information density and recording sensitivity, a photopolymerizable hardening resin has been proposed as a material for an intermediate layer provided between a substrate and a recording layer. For example, JP-A No. 55-4793 describes acrylic acid monoester, acrylic diester,
Acrylic triesters, acrylic tetraesters, and the like are described. As specific examples of diesters and triesters of acrylic acid, 1,3-propanediol diacrylate, diethylene glycol diacrylate, tetraethylene glycol diacrylate, and trimethylolpropane triacrylate are disclosed.

However, in a recording medium in which a layer made of a photopolymerizable resin is provided as an intermediate layer between a substrate and a recording layer, when the recording layer is of a pit-forming type, generally,
The recording sensitivity was lower than that of known recording media provided with an intermediate layer made of thermoplastic resin, and could not be said to be sufficient.

[Summary of the Invention] An object of the present invention is to provide an information recording medium with improved recording sensitivity.

The above object is to provide an information recording medium having a recording layer on a substrate in which information can be written and/or read by a laser, in which the following general formula (I) or (II) is provided between the substrate and the recording layer. An information recording medium comprising an intermediate layer containing a polymer of at least one photopolymerizable monomer selected from the group consisting of (meth)acrylic acid ester compounds represented by (III) and (III).

General formula (I): (However, R1 and R2 are each a hydrogen atom or a methyl group; X is -C2H40- or -C3H80
-; and y is an integer in the range of 6≦y≦12 when X is -C2H40-;
If O-, it is an integer in the range of 3≦y≦12)
General formula (■): RCOGO2= C-C0-(QC3Hs) + -0C
H2CHz = C-GO-(OC3He)
l-0CH2-GCHz = C-Go-(OC3H
s) k-OCHz CHzCH3 (however, R
”, R4 and R5 are each a hydrogen atom or a methyl group; and i, j and k are each O≦I≦9.
0≦j≦9. It is an ffi number in the range of O≦≦9, and is an integer that satisfies i+j+≧1) General formula (■): CHz = C-Go-(0(,3Hts) *
-0CH2R・1 GH2= C-GO-COC3H6) m -QC)
Il,s = r -rn-(IIr'!-Il
-) --nr=u- (however, Hg, R7 and R8 are each a hydrogen atom or a methyl group; and m, m and n are each O≦k≦9.0≦m≦9
．． An integer in the range O≦n≦9, and +m+n≧
Satisfy 1! ! That is, the present invention provides an intermediate layer containing a photopolymerizable curable polymer formed from the photopolymerizable (meth)acrylic acid ester compound described above between the substrate and the tR layer. This realizes a remarkable improvement in the sensitivity of information recording media.

The photopolymerizable curable polymer used in the present invention is:

Loss of thermal energy from the recording layer to the substrate can be effectively prevented and the sensitivity of the information recording medium can be increased.

In addition, when a photopolymerizable monomer is used as the intermediate layer material, unlike when using a thermoplastic polymer, there is no need to dissolve it in a solvent to form a solution, and when the monomer is polymerized and cured with light such as ultraviolet rays. , it has the advantage that a yI (pre-groove) for tracking can be easily formed by using a stamper.

The information recording medium of the present invention has the above general formula (I), (■), and /
Alternatively, by using a polymer formed by photopolymerization of a (meth)acrylic acid ester compound represented by (I), the photopolymerizable acrylic material specifically described in JP-A-55-4793 can be produced. Recording sensitivity can be significantly increased compared to the case of photocurable polymers using acid diester and acrylic acid triester compounds.

Until now, the sensitivity of information recording media having an intermediate layer made of a photocurable resin was significantly lower than that of a recording medium having an intermediate layer made of a thermoplastic resin such as polymethyl methacrylate. According to , it is possible to achieve a sensitivity comparable to that, and even higher sensitivity.

[Structure of the Invention] The information recording medium of the present invention having the preferable characteristics as described above can be manufactured, for example, by the following method.

The substrate used in the present invention can be arbitrarily selected from various materials used as substrates for conventional information recording media. Optical properties, flatness, processability of the substrate,
In terms of ease of handling, stability over time, and manufacturing cost,
Examples of substrate materials include glass such as soda lime glass; acrylic resins such as cell cast polymethyl methacrylate and injection molded polymethyl methacrylate; vinyl chloride resins such as polyvinyl chloride and vinyl chloride copolymer; and polycarbonate. be able to.

The surface of the substrate on which the recording layer is provided has improved flatness,
For the purpose of improving adhesive strength and preventing deterioration of the recording layer,
An undercoat layer may be provided.

Examples of materials for the undercoat layer include polymethyl methacrylate, acrylic acid-methacrylic acid copolymer, styrene/maleic anhydride copolymer, polyvinyl alcohol, N
- Methylolacrylamide/styrene sulfonic acid copolymer, chlorinated polyethylene, chlorosulfonated polyethylene, nitrocellulose, polyvinyl chloride, polyester, polyimide, vinyl acetate/vinyl chloride copolymer, ethylene/vinyl acetate copolymer, polyethylene, - Organic polymer materials such as polypropylene and polycarbonate;
and oxides (Sing, A-203, etc.), fluorides (M
Examples include inorganic substances such as gFz, etc.).

Especially when the substrate material is glass, alkali ions (Na'', K+, M g 2+, Ca
2'), etc.) from diffusing into other layers, for example, a polymer having a hydrophilic group or a maleic anhydride group as described in Japanese Patent Application No. 173676/1983 by the present applicant. Preferably, an undercoat layer consisting of a polymer having the following properties is provided.

The undercoat layer is formed by dissolving or dispersing the above-mentioned polymeric substance in a suitable solvent, and then applying this coating solution onto the substrate using a cold-blooded method such as spin code, dip coating, extrusion coating, barcode screen printing, etc. It can be formed by The thickness of the undercoat layer is generally 0.
01 to 20 #Lm, preferably Ool to 10
It is 4m.

In addition, in order to improve the adhesion between the glass substrate and the intermediate layer according to the present invention or between the glass substrate and the above-mentioned undercoat layer, an epoxy resin such as γ-glycidoxypropylmethoxysilane may be used. It is also suitable to provide a primer layer made of various silane coupling agents such as silane, aminosilane, and vinylsilane on the substrate.

Next, an intermediate layer is provided on the substrate, either directly or via a subbing layer (or primer layer).

The intermediate layer, which is a characteristic feature of the present invention, has the following general formula (I
), (II) or (l[) (me□ri)
This layer includes a photopolymerizable polymer whose monomer is at least one type of acrylic ester compound.

2" ILΣ: (However, R1 and R2 are each a hydrogen atom or a methyl group; X is -C2H40- or -C3H80
There is T; So L Te'! /-7'i, X is -C2H40-
When X is -C3H60-, it is an integer in the range of 6≦y≦12, and when X is -C3H60-, it is an integer in the range of 3≦y≦12!
In terms of the sensitivity of the information recording medium obtained (Ii number),
In the (meth)acrylic acid diester of ethylene glycol or propylene glycol represented by general formula (II), it is preferable that R1 and R2 are both hydrogen atoms.

Also, regarding y, which represents the number of ethylene glycol groups or propylene glycol groups, the larger the value of y, the higher the sensitivity of the recording medium, but on the other hand, from the viewpoint of the flexibility required for the intermediate layer, it is better to have a smaller y. is desirable, so when X is -C2H4o-, y is 8≦y≦10
Preferably, X is an integer in the range of -C3H,O-
In this case, y is preferably an integer in the range of 3≦y≦9, particularly preferably in the range of 3≦y≦6.

2" = L1: GHz = C-GO-(01; 3Hs) +
-0CHzGH2=CGo-(QC:iHs)
+ -0(:R2GCH2=C-Go-(0038
8) k -0CH20H20H3 (However, R3, R4
and R5 are each a hydrogen atom or a methyl group;
and i, j, and k are O≦i≦9.0≦j≦, respectively.
9, in the range O≦≦9! li number, and i+j
+ is an integer that satisfies ≧1) From the viewpoint of the sensitivity of the information recording medium, in the (meth)acrylic acid triester of propylene glycol represented by the general formula (II), Ri, R' and R5 are all hydrogen atoms. Preferably, i, j, and k are integers in the range of 1≦i≦5, ]≦j≦5.1≦, and ≦5.

2"L&"JL sword: GHz = C-GO-(0(,3Hs) z
・-0CHzGH2=C-C:0-(QC:3H
s) m-0CHCH2=C-GO-(QC3H
s) n-0CHZ (but R6, R7 and R8
are each a hydrogen atom or a methyl group; and 1.
m and n are respectively O≦mi≦9, O≦m≦9, O≦n
In terms of the sensitivity of the information recording medium, in the (meth)acrylic acid triester of propylene glycol represented by the general formula (He) , R7 and Re1 phantom kj
The h of the E hundred beams (ascending j ista sentence, m and n are,
Preferably, it is an integer satisfying 2≦k+m+n≦10.

The (meth)acrylic acid ester compound listed in L can also be used in combination with other known photopolymerizable monomers to form the intermediate layer.

In forming the intermediate layer, first, a coating solution (UV lacquer solution) is prepared by dissolving a polymerization initiator in a photopolymerizable monomer made of the above-mentioned (meth)acrylic acid ester compound.

Examples of photopolymerization initiators (sensitizers) include benzoin alkyl ethers, benzyl ketals, acetals, acetophenone, 11, benzophenone derivatives, xanthone derivatives, thioxanthone derivatives, anthraquinone derivatives, and benzaldehyde derivatives. These polymerization initiators can be used alone or in appropriate combinations.

Various additives such as antioxidants and stabilizers can be added to the monomer solution depending on the purpose.

Next, this coating liquid is applied onto the substrate by a coating method such as a spray method, a spinner method, a dip method, a roll coating method, a blade coating method, a doctor roll method, or a screen printing method to form a coating film, and then electromagnetic radiation is applied. By irradiating it with , the nitride in the coating film is polymerized and cured, and an intermediate layer is formed on the substrate (or primer layer or undercoat layer).

The electromagnetic radiation used may include ultraviolet radiation, electron beams, etc. Among these, ultraviolet rays are preferable from the viewpoint of equipment scale, economy, safety, etc. Furthermore, in order to carry out the polymerization reaction more completely, it is preferable that the irradiation with electromagnetic radiation be carried out under vacuum or under a nitrogen gas atmosphere.

Note that when forming the intermediate layer, a stamper or the like may be used to provide information such as address signals and guide grooves for tracking in the form of fine irregularities on the surface of the intermediate layer.

The layer thickness of the intermediate layer is usually 0.005 to 1100 IL, preferably 0.1 to 50 pm.

A recording layer is then provided on the intermediate layer.

Examples of materials used for the recording layer include Te, Zn, I
n, Sn, Zr, AfL, TE, Cu, Ge, Au,
Metals such as Pt; semimetals such as Bi, As, Sb; Ge, S
Semiconductors such as i; and alloys thereof or combinations thereof can be mentioned. Compounds such as sulfides, oxides, borides, silicon compounds, carbides, and nitrides of these metals or semimetals; and mixtures of these compounds and metals can also be used in the recording layer. Alternatively, a combination of dyes and polymers can be utilized.

In the present invention, it is particularly preferable that the material of the recording layer is a mixture of In and GeS. In this case, the In content in the recording layer is in the range of 33.3 to 87.5% (wt%). It is preferable that it is in 1.X.

The recording layer can be formed of the above-mentioned material on the substrate via an intermediate layer by a method such as vapor deposition, sputtering, or ion blasting. The recording layer may be a single layer or a multilayer, but its layer thickness is generally in the range of 100 to 5,500 layers, preferably in the range of 200 to 1,000 layers in view of the optical density required for optical information recording.

On the recording layer, a protective film made of natural polymeric substances such as gelatin and gelatin derivatives; synthetic polymeric substances such as cellulose derivatives, polysaccharides, and latex-like vinyl polymers is provided on the recording layer for the purpose of improving mechanical strength. may be provided.

In addition, a thin film made of an inorganic substance such as silicon dioxide, tin oxide, or magnesium fluoride is vacuum-deposited on the surface of the substrate opposite to the side on which the recording layer is provided in order to improve scratch resistance and moisture resistance. , sputtering, or the like.

In this way, an information recording medium in which the substrate, intermediate layer, and recording layer are basically laminated in this order can be manufactured.

In addition, in the above-mentioned bonded type recording medium,
It can be manufactured by joining two substrates having the above configuration using an adhesive or the like. In addition, in an air sandwich type recording medium, at least one of the two disc-shaped substrates has the above structure,
It can be manufactured by joining via a ring-shaped outer spacer and an inner spacer.

Next, Examples and Comparative Examples of the present invention will be described.

However, each of these does not limit the present invention.

[Examples 1 to 5] Soda lime glass substrate (4 inches x 4 inches, thickness: 1
．． 6 mm) was washed with an alkaline solution and isopropyl alcohol, and then dried with Freon.

A silane coupling agent [Structural formula: % formula %] Product name: KBM-403, manufactured by Shin-Etsu Silicon Co., Ltd.] was applied onto this substrate using a spinner with a rotation speed of 11,000 rpm, and then
A primer layer was formed by drying at a temperature of 100° C. for 5 minutes.

Next, a UV lacquer solution was prepared by dissolving 3 parts by weight of benzoin methyl ether in 100 parts by weight of the acrylic diester of ethylene glycol No. 001 below, and then filtered under pressure using a filter (pore size = 0°2 JLm) .

The obtained UV lacquer liquid was applied onto the primer layer of the glass substrate using a spinner. This coated substrate was placed in a transparent box filled with nitrogen gas, and exposed to ultraviolet light for 5 minutes using a 4WW ultra-high pressure mercury lamp, with a distance of 60 cm between the lamp and the substrate, until the thickness of one layer was 3.
An intermediate layer of 0 lum was formed.

Next, I was applied to the surface of the glass substrate by vacuum evaporation.
A recording layer having a layer thickness of 300λ was formed by co-evaporating n180λ and Ge5120λ.

In this way, an information recording medium consisting of a substrate, a primer layer, an intermediate layer, and a recording layer was manufactured in this order.

Furthermore, as a photopolymerizable monomer for forming the intermediate layer, the following N
Various information recording media consisting of a substrate, a primer layer, an intermediate layer and a recording layer were manufactured in this order by performing the same operations as described above except for using each of the acrylic ester compounds Nos. 002 to 5.

Acrylic ester type H No.l: Structural formula: No. 2: Structural formula: O No, 3: Structural formula: No, 4: Structural formula: [CHz = (ICO-(QC3Hs) 3-OC
Hz 13G ■ H2CH3 No, 5: Structural formula: % formula % However, vertical + m + n = 4 [Comparative example 1] In Example 1, a UV lacquer liquid consisting of acrylic acid diester of ethylene glycol was used as a coating liquid for forming the intermediate layer. Instead, polymethyl methacrylate (trade name:
2% solution of Dianal BR-85 (manufactured by Mitsubishi Rayon ■) (mixed solvent of ditoluene and methyl cellosolve)
After coating using a spinner, it is dried to a layer thickness of 0.
An information recording medium consisting of a substrate, a primer layer, an intermediate layer and a recording layer was manufactured in this order by performing the same operations as in Example 1 except for forming a 44 m long intermediate layer.

[Comparative Examples 2-lo3 In Example 1', the following (meth)acrylic acid ester compounds Nos. 6 to 14 were used instead of the acrylic diester of ethylene glycol as the photopolymerizable monomer for forming the intermediate layer. By performing the same operation as in Example 1 except for using the substrate, the primer layer,
Various information recording media consisting of an intermediate layer and a recording layer were manufactured.

Acrylic ester, H No. 6: Structural formula: No. 7: Structural formula: No. 8: Structural formula: No. 9: Structural formula: (CH2= CHCO-CH2) 2 CC, CHz
OH) 2No, 10: Structural formula 2 (CH2= CHCO0CHz ) 3 CGHz C
H3 No, 11: Structural formula: % formula % No, 12 Structural formula: No, 13: Structural formula: % formula %) No, 14: Structural formula: CH3 [Evaluation of information recording medium] Each obtained information recording medium The following sensitivity test was conducted for evaluation.

Ar ion laser light (wavelength: 514.5 nm) with a pulse length of 100 n5ec was transmitted by a modulator to a distance of 1.74 m on the recording layer of an information recording medium using a WJ microscopic objective lens.
The output intensity of the laser necessary to form a pit with a diameter of about IILm in the recording layer was measured.

The results obtained are shown in Table 1.

Table 1 Sensitivity (mW) Example 1 (No, l) 11.0 Example 2
(No, 2) 11.0 Example 3 (
No, 3) 12-1 Example 4 (No-4
) 12.1 Example 5 (No, 5)
12.1 Comparative Example t 12.1 Sensitivity (m W ) Comparative Example 2 (No, 6) 14.3 Comparative Example 3
(No-7) 13.2 Comparative Example 4 (N
o, 8) 14.3 Comparative Example 5 (No, 9'
) 13.2 Comparative Example 6 (No, lO)
13.2 Comparative Example 7 (No, ll) 14
．． 3 Comparative Example 8 (No, L2) 16.5 Comparative Example 9 (No, 13) 17.6 Comparative Example 10 (
No. 14) 16.5 As is clear from the results shown in Table 1, the information recording medium of the present invention (Examples 1 to 5)
) had a recording sensitivity equal to or higher than that of the information recording medium provided with a known heat insulating layer (Comparative Example 1). In addition, the information recording medium of the present invention had significantly higher recording sensitivity than other information recording media having intermediate layers made of photopolymerizable resins (Comparative Examples 2 to 10). Therefore, it has been found that the photopolymerizable layer used in the deployment medium of the present invention is very useful as a material for the intermediate layer.

Claims (1)

[Claims] 1. Writing information on the substrate by laser and/or
Or, in an information recording medium having a readable recording layer, the following general formula (I) is used between the substrate and the recording layer.
Information characterized in that an intermediate layer containing a polymer of at least one photopolymerizable monomer selected from the group consisting of (meth)acrylic acid ester compounds represented by , (II) and (III) is provided. recoding media. General formula (I): ▲There are mathematical formulas, chemical formulas, tables, etc.▼ (However, R^1 and R^2 are each a hydrogen atom or a methyl group; X is -C_2H_4O- or -C
_3H_8O-; and y means that X is -C_2H_
When X is -C_3H_8O-, it is an integer in the range of 6≦y≦12, and when X is -C_3H_8O-, it is 3≦y≦12.
General formula (II): ▲There are mathematical formulas, chemical formulas, tables, etc.▼ (However, R^3, R^4 and R^5 are each a hydrogen atom or a methyl group; and i, j and k are integers in the range of 0≦i≦9, 0≦j≦9, 0≦k≦9, and are integers that satisfy i+j+k≧1) General formula (III): ▲ Formula, There are chemical formulas, tables, etc.▼ (However, R^6, R^7 and R^8 are each a hydrogen atom or a methyl group: and l, m and , n
are integers in the range of 0≦l≦9, 0≦m≦9, 0≦n≦9, and satisfying l+m+n≧1) 2. The substrate is a glass substrate. An information recording medium according to claim 1. 3. The information recording medium according to claim 1, wherein the recording layer is made of a mixture of metal and nonmetal. 4. The information recording medium according to claim 1, wherein an undercoat layer made of a thermoplastic resin is provided between the substrate and the intermediate layer. 5. The information recording medium according to claim 1, wherein a primer layer made of an organic silane compound is provided between the substrate and the intermediate layer. 6. Between the substrate and the undercoat layer made of thermoplastic resin,
5. The information recording medium according to claim 4, further comprising a primer layer made of an organic silane compound.