JPH022067A - optical information recording medium - Google Patents

Abstract

PURPOSE:To obtain an optical data recording medium enhanced in stability and reliability by containing an org. solvent soluble resin in the recording layer on a plastic substrate in a specific amount with respect to an org. dye. CONSTITUTION:Any optical change is generated in a recording layer by the irradiation with laser beam and data can be recorded on the basis of said change and the dye main component of said recording layer is composed of an org. dye such as a polymethine dye. Further, in order to enhance the reflectivity and sensitivity of the recording layer, an org. solvent soluble resin is contained in a specific amount. This org. solvent soluble resin is excellent in film forming properties and well in the compatibility of the org. dye and, therefore, it is uniformly dispersed in the org. dye. As a result, the reflectivity and optical sensitivity of the recording layer are enhanced. The use ratio of the org. solvent soluble resin is 0.01-18%, pref., 0.1-10% by wt. of the org. dye and, when the use ratio is below 0.01wt.%, sensitivity enhancing effect is lowered and, when the use ratio exceeds 18wt.%, the reflectivity of the recording layer is reduced to a large extent.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an improved optical information recording medium that can be used in the optical recording field.

[Conventional technology]

Optical recording methods have the advantages of being able to record and read without contact, being easy to handle, being resistant to scratches and dust, and having a storage capacity tens to hundreds of times larger than magnetic recording methods. Therefore, it is expected to be used for data files such as code information and image information.

Among other things, the user can read directly after writing.

There is a lot of interest in so-called write-once optical recording media.

Research is being actively conducted to meet the demands for high sensitivity, high stability (optical/mechanical), high quality, etc., especially regarding recording materials.

By the way, the recording material used in this type of optical recording medium is required to have appropriate light absorption coefficient and reflectance.

Conventionally, metal or metal alloy thin films such as Te and TQ, TaO
Metal compound thin films such as x thin films, silver lead thin films, etc. were used. However, since these metal thin films are formed using vacuum thin film forming techniques such as sputtering and vacuum evaporation,
There are problems in terms of mass production, etc., and the resulting optical recording medium is expensive.

Under these circumstances, organic dye materials are used as recording materials,
Optical recording media have been proposed in which a recording layer is formed by coating means. Optical recording media using such organic dye materials as recording materials can be said to have high practicality in terms of mass production and product cost, since the recording layer can be applied by means such as a spin code.

5. This organic dye-based optical recording medium is of a type in which a reflective film is provided between the substrate and the recording layer and the difference in reflectance in the reflective film is read as a signal. There is a type that directly reads the reflectance of a recording layer containing an organic dye through a transparent substrate, but the former requires a reflective film to be formed by a method such as vapor deposition, which reduces the process advantage and reduces the reflection of the underlying layer. Since the film has a high thermal conductivity, it has drawbacks such as a large energy loss and the need to increase the output of the laser for irradiation more than necessary.

Therefore, since dyes with high reflectance have appeared due to advances in dye synthesis technology, optical recording media in which the reflectance of a recording layer containing the above-mentioned organic dye can be directly read through a transparent substrate have been actively used.

The optical recording medium utilizes the rapid rise in temperature of the recording layer in the irradiated area when an organic dye absorbs laser light, and forms recording pits by melting, sublimating, and decomposing the dye. be. Therefore, the organic dye material used must be able to effectively absorb the laser light in the wavelength range of the laser light, reflect the laser light well in this wavelength range, and be soluble in an appropriate solvent. characteristics are required.

The above-mentioned dyes have large absorption in the near-infrared region, which is the wavelength range of semiconductor lasers, for example, and also have high reflectance in the near-infrared region, so they are considered promising as recording materials for write-once optical recording media.

However, conventionally known optical information recording media of this type do not necessarily have a high reflectance and have insufficient sensitivity, so they are not stable and highly reliable.

In particular, it has an air sandwich structure in which a pair of recording media is sealed with the recording layer inside through a space with another substrate, and recording is performed by forming pits that can be written only once by irradiation with recording light. This tendency is clearly seen in optical information recording media of this type, and improvement thereof has been strongly desired.

[Problem to be solved by the invention]

An object of the present invention is to solve the above-mentioned problems found in conventional optical information recording media, and to provide an optical information recording medium that has high reflectance and high sensitivity, and is therefore stable and reliable. do.

[Means to accomplish the task]

The above object is achieved by incorporating a specific amount of organic solvent-soluble resin into the recording layer of an optical information recording medium using a plastic substrate.

The optical information recording medium of the present invention basically consists of an organic solvent-soluble resin on a plastic substrate with a ratio of 0.0 to an organic dye.
The recording layer contains 1% by weight to 18% by weight, but if necessary, an undercoat layer may be provided between the substrate and the recording layer, or a protective layer may be provided on the recording layer. Alternatively, the pair of recording media configured in this manner may be formed into an air sandwich structure in which the recording layer is placed inside and sealed with another substrate through a space, or a tight sandwich structure in which the pair of recording media is bonded through a protective layer. The protective layer may be formed on the recording layer or may be on the surface of the substrate opposite to the recording layer.

Next, the materials constituting the optical information recording medium of the present invention and the necessary characteristics of each layer will be specifically explained.

(1) Substrate As a necessary characteristic of the substrate, it must be transparent to the laser beam used only when recording and reproducing is performed from the substrate side, and it does not need to be transparent when recording and reproducing is performed from the recording side. As the substrate material, plastics such as polyester, acrylic resin, polyamide, polyolefin resin, phenol resin, epoxy resin, polyimide, polycarbonate resin, etc. can be used.

Note that a preformat such as an address signal or a pregroove for a guide groove may be formed on the surface of the substrate.

As a method for forming the preformat and pregroove, known methods such as the so-called 2P method and the injection method are employed.

(2) Recording layer The recording layer is a layer that causes some kind of optical change by irradiation with laser light and can record information based on that change.The main component of the recording layer is an organic dye such as a polymethine dye.
Furthermore, in order to improve the reflectance and sensitivity of the recording layer,
Contains a specific amount of organic solvent-soluble resin.

This organic solvent-soluble resin has excellent film-forming properties and good compatibility with the organic dye, so it is uniformly dispersed in the organic dye. This seems to improve the reflectance and photosensitivity of the recording layer.

The ratio of organic solvent-soluble resin used is 0.0 to organic dye.
1% to 18% by weight, preferably 0.1% to 2% to 10% by weight. If the proportion used is less than 0.01% by weight, the sensitivity improvement effect will be reduced, and if it exceeds 18% by weight, the reflectance of the recording layer will be significantly reduced.

Specific examples of the organic solvent-soluble resin used in the present invention are shown below.

R1) Ionomer-based laterally open R2) Polyolefin resins such as ethylene-vinyl acetate copolymer, ethylene-vinyl acetate copolymer,
Acrylate copolymers, ethylene-acrylic acid copolymers, etc.

R3) Halogen polyolefin resin such as polyvinyl chloride, polyvinylidene chloride, vinyl acetate-vinyl chloride copolymer, copolymer of acrylic acid ester or methacrylic acid ester and vinyl chloride,
Vinylidene chloride-vinyl chloride copolymer, etc.

R4) Polystyrene and styrene copolymer polystyrene, styrene-acrylonitrile copolymer (AS resin)
, styrene-acrylonitrile-butadiene copolymer (
ABS resin), styrene-butadiene copolymer, styrene-butadiene-methyl methacrylate copolymer (M
BS41 fat) etc.

R5) Coumarone-indene resin R6) Acrylic resin polyacrylate, polyacrylonitrile, acrylonitrile copolymer, etc.

R7) Polyvinyl acetate and copolymers thereof Vinyl acetate copolymers include copolymers with ethylene, vinyl chloride, and the like.

R8) Polyvinyl ether For example, polyvinyl isobutyl ether.

R9) Polyamide resin such as nylon 6, nylon 66, nylon 610,
Nylon 612, Nylon 9, Nylon 11° Nylon 12. In addition to homopolymers such as nylon 13, nylon CM4000 (#l manufactured by Toshi Co., Ltd.), and nylon CM8000 (manufactured by Toshi Co., Ltd.), nylon 6/66/610, nylon 6/
66/12, nylon 6/66/11, nylon 676
Copolymers such as 6/610/12, modified nylon, etc.

10R) Polyester resin For example, various dibasic acids such as aliphatic dibasic acids such as oxalic acid, succinic acid, maleic acid, adipic acid, and cepatic acid, or aromatic dibasic acids such as isophthalic acid and terephthalic acid, and ethylene. Mixtures and cocondensates with glycols such as glycol, tetramethylene glycol, and hexamethylene glycol are suitable. Among these, condensates of aliphatic dibasic acids and glycols,
More preferred are cocondensates of glycols, aliphatic dibasic acids, and aromatic dibasic acids. Furthermore, for example, a modified glybutal resin obtained by esterifying and modifying glybutal resin, which is a condensation product of phthalic anhydride and glycerin, with a fatty acid, a natural resin, etc., is also preferably used.

11R) Polyvinyl acetal resin Polyvinyl acetal resins such as polyvinyl formal, polyvinyl acetoacetal, and polyvinyl butyral obtained by acetalizing polyvinyl alcohol are preferably used. In this case, the degree of acetalization of the polyvinyl acetal resin can be arbitrary, for example, BL-1, 2, 3, S; BX-1°U;
BM-1, 2, 5, S; BH-3 (S-LEC B type manufactured by Building Block Chemical).

R12) Polyurethane resin Thermoplastic polyurethane resin having urethane bonds - In particular, polyurethane resin obtained by condensation of glycols and diisocyanates.

In particular, polyurethane resins obtained by condensation of alkylene glycol and alkylene diisocyanate are preferred.

R13) Nitrogen-containing vinyl polymers, such as polyvinylpyrrolidone and polyvinylcarbazole.

R14) Polyimide resins R15) Polyethers such as polyethylene oxide and glycols,
Polyphenylene oxide (ppo), modified polyphenylene oxide (noryl), thermoplastic bisphenol epoxide obtained by condensation of bisphenol A and epichlorohydrin, etc.

R16) Polycarbonate such as polydioxydiphenylmethane carbonate,
Various polycarbonates such as polydioxydiphenylethane carbonate and dioxydiphenylpropane carbonate.

R17) Cellulose resins such as acetyl cellulose, propyl cellulose,
Methylcellulose, ethylcellulose, hydroxyethylcellulose, etc.

R18) Polyvinyl ketones such as polymethyl vinyl ketone, polymethyl isopropenyl ketone, polyphenyltone, etc.

R19) Sulfur-containing polymer needle polysulfone resin Polyether sulfone resin Polyphenylene sulfide R20) Urea resin R21) Ketone resin R22) Alicyclic solid epoxy resin R23) Alicyclic solid epoxy-nylon copolymer resin R
24) The above alicyclic solid epoxy S-LEC B resin (@
(manufactured by Miki Kagaku Co., Ltd.) Copolymer resin R25) Acetate resin R26) Carboxy vinyl polymer R27) Silicone resin, etc.

All of the organic solvent soluble resins mentioned above can be used for substrates formed by the 2P method, but for substrates formed by the injection method, for example, ionomer resins, styrene-acrylonitrile copolymer (AS), etc. resins), polyvinyl acetate, polyamide resins, polyvinyl acetal resins, polyvinylpyrrolidone, polyethylene oxide and glycol, acetyl cellulose, propyl cellulose, alicyclic solid epoxy resins such as spiroepoxy (manufactured by Daicel); Cyclic solid epoxy resin-nylon copolymer resin, alicyclic solid epoxy resin-Eslec B resin (manufactured by Block Chemical Co., Ltd.), carboxyvinyl polymer, etc. that are soluble in alcohol or a mixed solvent containing alcohol as a main component. It is desirable to use resin.

Any organic dye can be used as long as it has both the property of absorbing the wavelength of recording light and the property of reflecting the wavelength of reproduction light.

Such organic dyes include dyes already proposed by the present inventors, such as cyanine, merocyanine, triphenylmethane, naphthoquinone, xanthine, and squalium dyes, as well as azo, stilbene, and phthalocyanine direct dyes, and azo , anthraquinone, triphenylmethane, xanthine, azine acid dye, cyanine,
Azo, azine, triphenylmethane-based basic dyes, azo, anthraquinone, xanthine, triphenylmethane-based mordant/acidic mordant dyes, anthraquinone, indigoid-based vat dyes, azo, anthraquinone, phthalocyanine, triphenylmethane-based dyes. Oil-soluble dyes and the like can be used.

Particularly in the present invention, it is desirable to use cyanine dyes or merocyanine dyes as shown below.

[Cyanine dye] represents a group, a substituted or unsubstituted aryl group, or an acyloxy group, xe represents an acid anion, and Q,
m and n are 0 or 1. ) [Merocyanine dye] or (wherein R1 and R2 represent a substituted or unsubstituted alkyl group, a substituted or unsubstituted aralkyl group, or an alkenyl group, and Zl and z2 complete a substituted or unsubstituted heterocycle) Indicates a necessary atomic group, z indicates an atomic group necessary to complete a substituted or unsubstituted 5-membered ring or 6-membered ring, and the 5-membered ring or 6-membered ring is fused with an aromatic ring. R1 represents a hydrogen atom or a halogen atom, R4 and R5 represent a hydrogen atom, a halogen atom, a hydroxy group, a carboxyl group, a ring such as an alkyl group, and the benzene ring and naphthalene ring in the above formula are substituted. You can.

Examples of solvents used for coating the organic dye and the organic solvent-soluble resin on the substrate include ketone-based solvents such as acetone, methyl ethyl ketone, and cyclohexanone; ester-based solvents such as butyl acetate, ethyl acetate, and carpitol acetate; and methyl cellosolve. , ethyl cellosolve,
Ether systems such as tetrahydrofuran and 1,4-dioxane ether; aromatic systems such as toluene and xylene; methanol.

Any one or more of organic solvents such as alcohols such as ethanol, isopropyl alcohol, and 1-butanol; and halogenated hydrocarbons such as dichloromethane, dichloroethane, and chloroform are suitable. Particularly in the case of the injection method, an alcohol system or a mixed solvent system containing alcohol as a main component is suitable.

In order to improve recording characteristics and stability, the recording layer of the present invention may contain other dyes, if necessary, such as phthalocyanine, tetrahydrocholine, dioxazine, triphetchazine, phenanthrene, anthraquinone, and xanthine. dyes, triphenylmethane-based, triphenylamine-based, azulene-based dyes, and metals or metal compounds, such as In.

Sn, Te, Bi, AQ, Sa, Too,
, SnO, Ag, Cd, Zn, etc. may be dispersed therein, or may be laminated.

The recording layer may also contain stabilizers, storage stabilizers (metal complexes, phenolic compounds), dispersants, flame retardants, lubricants, plasticizers, and the like.

Various stabilizers can be used as such stabilizers, but in particular, stabilizers that greatly improve stability and light resistance,
Transition metal chelate compounds are preferred because they increase absorption of long-wavelength writing laser beams, reduce reproduction deterioration, and have good compatibility with dyes. In this case, As the central metal,
Ni, Co.

Cu, Mu, etc. are preferred, and for example, the following compounds are preferred.

In addition, the transition metal chelate compound is 700 to 85
Those with absorption at 0rv+, especially 700-8
It is preferable that the material has a maximum absorption wavelength of 50 nm.

1) Acetylacetonate chelate QI Ni (■) Acetylacetonate Q2 Cu
(II) Acetylacetonate Q3 Mn(m) Acetylacetonate 04 Co(n) Acetylacetonate 2) Bisdithio-α-diketone system Here, R (11-H+41 represents an alkyl group or an aryl group, Represents a divalent transition metal atom.

Q5 Ni (U ) dithiobenzyl Q6 Ni (n ) dithiobiacetyl 3) bisphenyldithiol system Here, R s + and R181 represent an alkyl group such as a methyl group, or a halogen atom such as Cn, and N represents a divalent transition metal atom such as Ni.

Furthermore, there may be further coordination above and below the above structure.

As such, the following are commercially available.

QIOPA-1002 (same as above) Qll PA-1003 (same as above) 012 PA-1005 (same as above) Q13 PA-1006 (same as above) 4) Salicylaldehyde oxime system 22, R'71 and R'1 are represents an alkyl group, and represents a divalent transition metal atom.

Q14 Ni(II)0-(N-isopropylformimidoyl)phenol Q15 N1(II)O-(N-dodecylformimidoyl)phenol Q16 Co(II)O-(N-dodecylformimidoyl)phenol Q17 Cu (n) O-(N-dodecylformimidoyl)phenol Q18 N1(II)2.2'-[trilomethylidine on ethylene bis]-diphenol 019 Co(U)2.2'-(ethylene bis )]-diphenol 020 N1(If)2.2'-(1,8-naphthylene bis-trilomethylidine)]-diphenol Q21 N1(II)-(N-phenylformimidoyl)phenol Q22 Co(II) -[N-phenylformimidoyl]phenol Q23 Cu(II) -[N-phenylformimidoyl]phenol Q24 N1 (If) salicylaldehyde phenylhytosine Q25 N1 (If) salicylaldehyde oxime 5)
The thiobisferrate chelate system 22 is the same as the mainland above, and R+91 and R(1
111 represents an alkyl group, and Ft +1111
represents an amino group.

Q26 N1(II) n-butylamino(2,2'-thiobis(4-tart-octyl)-ferulate)Q
27 N1(II)n-butylamino[2,2'-thiobis(4-tert-octyl)-felt]Q29 Such a transition metal chelate compound (stabilizer) is synthesized according to a known method.

The transition metal chelate compound is 1% by weight to 100% by weight based on the organic dye. #, %, especially 10% by weight ~ 35
Contains about % by weight.

The thickness of the recording layer is 100 μm to 10 μm, preferably 200 μm.
~2000 people. Methods for forming the recording layer include solvent coating method 1, such as dip coating, spray coating, spinner coating, blade coating,
Roller coating, curtain coating, etc. can be used.

(3) Undercoat layer The undercoat layer (a) improves adhesion, (b) serves as a barrier against water or gas, (c) improves storage stability of the recording layer, and (d)
) improvement of reflectance, (e) protection of the substrate from solvents, (f)
Used for purposes such as forming pre-grooves. (a
), various polymer materials such as ionomer resins, polyamide resins, vinyl resins, natural resins, natural polymers, silicones, liquid rubbers, and silane coupling agents can be used. ,(b)
For the purpose of (C), inorganic compounds such as Bib2, MgF2.5iO1Tie,
, ZnO, TiN, SiN, etc., metals or metalloids such as Zn, Cu, S, Ni, Cr, Ge, S
e, Au, Ag, Al2, etc. can be used. Also, for the purpose (d), metals such as Al
Ag, etc., or an organic thin film with metallic luster, such as methine dye, xanthine dye, etc., can be used, and (a)
For the purpose of (f) and (f), ultraviolet curing resins, thermosetting resins, thermoplastic resins, etc. can be used.

(4) Protective layer The protective layer (a) protects the recording layer from scratches, dust, dirt, etc., and (b) improves the storage stability of the recording layer.

(C) Used for the purpose of improving reflectance, etc. For these purposes, the materials listed above for the undercoat layer can be used.

In the present invention, the undercoat layer and the protective layer may contain stabilizers, dispersants, flame retardants, lubricants, antistatic agents, surfactants, plasticizers, etc., as in the case of the recording layer. . Furthermore, the above-mentioned compound according to the present invention can also be contained in the undercoat layer and the protective layer.

To record information signals on the obtained optical recording medium.

A focused laser beam is irradiated onto the recording material from the transparent substrate side, melting it, decomposing it, sublimating it, and forming a perforated recording pit that can be written by - degrees. Also, when reproducing, the information signal can be read by irradiating a laser beam of a predetermined wavelength from the transparent substrate side and reading the difference in reflectance between the pit portion and the space portion (portion where no pits are formed). .

The laser beam to be irradiated may be appropriately selected depending on the absorption wavelength of the recording material (that is, organic dye), and specifically, semiconductor laser, CO□ gas laser, Ar gas laser, He
Examples include -Ne gas laser, ruby laser, dye laser, and the like.

〔effect〕

The optical information recording medium according to the present invention has high reflectance and good sensitivity, so it has excellent stability and improved reliability.

〔Example〕

Next, the present invention will be further explained with reference to Examples.

The present invention is not limited to this.

Example 1 Benzoin isobutyl ether 2 parts by weight Isopropyl alcohol 50 Toluene
Stir and mix 10 or more mixtures and make a diameter 2
00. ++N and two 12 m thick polymethyl methacrylate discs were coated by dipping, dried for 15 minutes, and then exposed to ultraviolet rays from a 2 KV high-pressure mercury lamp from a distance of 20 am for 15 min.
Irradiated for seconds.

In addition, a solution containing (manufactured by N Co., Ltd.) was applied and dried to a thickness of 650 mm.
After forming the human recording layer, it was bonded and sealed with an adhesive via ABS inner and outer spacers having a thickness of 1+m+. As the adhesive, one having the following composition was used.

After dropping benzoin isobutyl ether 3 on a Ni stamper, the plates obtained earlier were stacked and pressed together and irradiated with ultraviolet rays from a 2KW high-pressure mercury lamp for 30 seconds from a distance of 20 countries. By peeling it off, the stamper mold was clearly transferred to the acrylic plate.

A 0.7% by weight 2,2'-dichloroethane solution of cyanine dye NK2883 (manufactured by Nippon Kanko Shokuryo Co., Ltd.) was prepared on the side where the stamper mold was transferred to the two acrylic plates mentioned above, and this was added to the dye. On the other hand, carbonate with a weight ratio of 18% and PA-1006 (Mitsui Toatsu-phi) with a weight ratio of 15% are used. At first, pulse irradiation was applied to one of the two sides, and then the other side was written.

When read with a power of 0.23 mW, the reflectance was 20.8%, and the sensitivity was improved by 3% compared to the recording layer containing no polycarbonate.

Examples 2 to 4 Optical information recording media were prepared in exactly the same manner as in Example 1, except that the resin contained in the recording layer had the structure shown in Table 1 below. When the reflectance and sensitivity were measured in the same manner as in Example 1, the results shown in Table 1 were obtained.

Table-1 Two bonate substrates were used, and each substrate was coated with 1% by weight of the following cyanine dye and 0.1% of nylon (CM4000, manufactured by Toshi).
A solution consisting of 20 parts by weight of 1,2-dichloroethane containing 5% by weight, 78 parts by weight of methanol, 3 parts by weight of isopropyl alcohol and 0.5 parts by weight of n-butanol was prepared.

*: Value compared to the sensitivity of an optical disc that does not contain resin in #iM.

Example 5 Each recording medium was manufactured by coating and drying a solution containing polycarbonate with a guide groove having a diameter of 130 I and a thickness of 1 m to form a recording layer with a thickness of 600 mm. Two recording media with a thickness of 1
They were bonded and sealed with an adhesive through an ABS spacer of 100 mm. An adhesive having the following configuration was used.

ERL 4299 100 Weight 2 Table-2 The ultraviolet light source is a high-pressure mercury lamp (UVT manufactured by Ushio Inc.
, -zooo-os) at an irradiation distance of 1O■ and an irradiation time of 45 seconds.

In the air sandwich structure optical disk thus fabricated, a semiconductor laser with a power of 3.8 m11 was used.
The laser was irradiated with light at a wavelength of μmφ, and pulse irradiation was first performed on one of the two surfaces, and then the other surface was written.

When read out with a power of 0.23 mW, the reflectance of the recording layer was 18.2%, and the sensitivity was 4.5% compared to the recording layer that did not contain nylon CM4000.
Improved.

Examples 6 to 10 Optical information recording media were produced in exactly the same manner as in Example 5, except that the resin contained in the recording layer had the structure shown in Table 2 below, and the reflectance and Sensitivity Example 5
Measurements were made in the same manner as above, and the results shown in Table 2 were obtained.

*: Value compared to the sensitivity of an optical disc whose recording layer does not contain resin.

Claims (1)

[Claims] (1) In an optical information recording medium in which a recording layer containing an organic dye as a main component is provided on a plastic substrate directly or via an undercoat layer, and a protective layer is further provided as necessary, an organic solvent is contained in the recording layer. Soluble resin to organic dye 0.0
An optical information recording medium characterized by containing 1% to 18% by weight.