JPH0427959B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a compound for optical recording media comprising a photopolymerizable monomer. Optical recording media that use a thin film of an organic compound as a recording layer have been known for some time, and are also disclosed in, for example, Japanese Patent Laid-Open Nos. 56-16948 and 1982-125246. All of them relate to laser recording media in which recording layers are made of organic dyes and recording and reproduction are performed using laser beams. In particular, the medium disclosed in JP-A-58-125246 has the general formula (I) The recording layer is a thin film of a cyanine dye represented by: A cyanine dye solution represented by formula (I) is coated on a plastic substrate to a thickness of 1000 Å or less, for example about 300 Å, using a spin coater or the like to form a thin film. molecular distribution within the membrane,
If the orientation is random, light scattering occurs within the film upon light irradiation, and when viewed microscopically, the degree of chemical reaction that occurs each time the film is irradiated with light differs. Therefore, it is desirable for the recording medium to have a uniform molecular distribution and orientation within the film, and it is also required that the film thickness be as thin as possible in order to achieve high recording density. However, when using the coating method,
The film thickness has a limit of about 300 Å, and the random distribution and orientation of molecules within the film has been difficult to solve. A diacetylene compound cumulative film, which has been proposed as a resist material with high photon efficiency and excellent resolution, has been used not only as a resist material but also as a thin film electro-optic device, electro-acoustic device, pressure/focus device, etc. It has been reported in Japanese Patent Application Laid-open No. 56-42229 and No. 56-43220 that it can be applied to electrical devices, etc.
This is shown in the issue of the publication, etc. Recently, Japanese Patent Application Laid-open No. 111029/1983 discloses an improvement in the method for producing a diacetylene compound cumulative film. The diacetylene compound cumulative film on the substrate produced according to the invention can be polymerized by irradiation with ultraviolet rays to form a diacetylene compound polymer film, or masked and irradiated with ultraviolet rays to partially polymerize and remove the unused material. The overlapping portions are removed to create shapes, which are used as thin film optical devices and integrated circuit elements. However, all of these are limited to diacetylene compounds, and there is no mention of the possibility of erasing once recorded data when used as a thin film optical device. An object of the present invention is to provide a compound for use in high-density optical recording media that can be used repeatedly and that can erase recorded information. The object of the present invention is achieved by the following compound for optical recording media. That is, the object of the present invention is achieved by a compound for optical recording media comprising a photopolymerizable monomer having a hydrophilic group, a hydrophobic group, and at least one unsaturated bond in the molecule. The photopolymerizable monomer of the present invention can form a monomolecular film or a monomolecular layer stack on a substrate. A recording layer of an optical recording medium can be manufactured using these films. Recording in manufactured optical recording media involves irradiating the photopolymerizable monomer of the recording layer with light to cause a polymerization reaction in the irradiated area, thereby creating a difference between the non-irradiated area and the irradiated area based on the presence or absence of polymerization. It is done by Regeneration is then carried out by measuring the difference caused by this polymerization in various ways. Further, the recorded information is removed by depolymerization by heating. As the photopolymerizable monomer of the present invention, a wide variety of photopolymerizable monomers can be used as long as they have a hydrophilic group, a hydrophobic group, and at least one unsaturated bond in the molecule. Such photopolymerizable monomers have the general formula (a),
It can be represented by (b) and (). R ₁ −CH=CH−R ₂ (a) R ₁ −CH=CH−R ₃ −CH=CH−R ₂ (b) R ₁ −C≡C−C≡−R ₂ () Above formula (a) In and (), both a hydrophilic site and a hydrophobic site exist in the R ₁ part or in the R ₁ and R ₂ parts, or R ₁ is hydrophobic in relation to R ₂ and R ₂ is It is hydrophilic in relation to R ₁ . In the above formula (b), R ₁ ,
Both a hydrophilic site and a hydrophobic site are present in either the R ₂ or R ₃ portion, or any of R ₁ , R ₂ and R ₃ is hydrophobic in relation to the other portion, Any of the remaining parts are hydrophilic. Especially long-chain alkyl groups with 10 to 30 carbon atoms.
A photopolymerizable monomer having ₁ part of R, 2 parts of R ₁ and R ₂ , or at least ₃ parts of R ₁ , R ₂ or R is desirable. Specific examples of the photopolymerizable monomer of the present invention include the following compounds. _CH3- ( _CH2 )x-C≡C-C≡C-( _CH2 )y-
COOH (both x and y are 0 or positive integers and 10≦X
+Y≦30) R=-( _CH2 ) _nCH3X = ^Cl- , Br- ^{, I-} , _ClO4- ^,

【formula】,

[Formula], etc. Is the above photopolymerizable monomer known per se (Reference title: Kagaku to Kogyo Vol. 32, No. 10, pp. 763-765), except for the fact that a long-chain alkyl group is newly introduced? , or a compound with a similar structure. Therefore, it can be synthesized by a known method. For example, a long chain alkyl group with 18 carbon atoms (n
1,4-di-n-octadecanoyl-2,5-distyrylpyrazine perchlorate which is a photopolymerizable olefin monomer having -octadecanoyl group) A~
can be synthesized by the following method. 10.8g 2,5-dimethylpyrazine and 44.5gp-chlorobenzenesulfonic acid-n-octadecanoyl ester were dissolved in 100ml DMF and heated under reflux for 1 hour under nitrogen atmosphere. After cooling, add a solution of 10 g of sodium perchlorate in 200 ml of water. After washing the precipitated solid with ether, it is recrystallized in methyl alcohol. 4.7 g of 1,4-n-octadecanoyl-2,5-dimethylpyrazine perchlorate and 1.04 g of benzaldehyde thus obtained were heated under reflux in acetic anhydride for 3 hours, and after cooling, recrystallized in methyl alcohol. to obtain A~ (yield 40%).
Other compounds can also be synthesized by a similar method. As a method for producing the monomolecular film or monomolecular layer stack, for example, the Langmuir project method (LB method) developed by I. Langmuir et al. is used. The Langmiur-Prodgiett method is used to analyze molecules with a structure that has a hydrophilic group and a hydrophobic group within the molecule.
When the balance between the two (balance of amphiphilic properties) is maintained appropriately, molecules form a monomolecular layer on the water surface with their hydrophilic groups facing down. This is a method of creating a cumulative film.
A monolayer on the water surface exhibits characteristics of a two-dimensional system. When the molecules are sparsely dispersed, the two-dimensional ideal gas equation ΠA=kT holds true between the area A per molecule and the surface pressure Π, resulting in a "gas film." Here, k is Boltzmann's constant and T is absolute temperature. If A is made sufficiently small, the intermolecular interaction will become stronger, resulting in a two-dimensional solid "condensed film (or solid film)". The condensed film can be transferred layer by layer to the surface of a substrate such as glass. Using this method, a monomolecular film or a monomolecular layer stack is produced, for example, as follows. First, a photopolymerizable monomer is dissolved in a solvent, and this is spread in an aqueous phase to precipitate the photopolymerizable monomer in the form of a film. Next, to prevent this precipitate from freely diffusing on the aqueous phase and spreading too much, a partition plate (or float) is installed to limit the area of development and control the state of aggregation of the film substance, and the Obtain surface pressure. By moving this partition plate, the developed area can be reduced to control the aggregation state of the membrane material, and the surface pressure can be gradually increased to set a surface pressure suitable for producing a cumulative membrane. The monomolecular film is transferred onto the substrate by gently vertically moving the clean substrate up and down while maintaining this surface pressure. A monomolecular layer film is produced as described above, and a monomolecular layer cumulative film having a desired degree of accumulation is formed by repeating the above-mentioned operations. The film-forming molecules are selected from one or more of the photopolymerizable monomers described above. When two or more types of photopolymerizable monomers are used, each monolayer consists of one type of photopolymerizable monomer. A method for combining a monomolecular layer composed of different film-forming molecules is, for example, by adding two types of photopolymerizable monomers a and b to the substrate side (ab) _o , (a _n b _l ) _o ,
a(b) _o (n, m, l are positive integers of 1 or more), etc., or they may be accumulated in a completely random order, and various combinations are possible. The combination method is determined depending on the characteristics of the photopolymerizable monomers used. The suitable thickness of the recording layer is 30 Å to 3 μm, especially
100 Å to 3000 Å is suitable. The selection of the type of photopolymerizable monomer, the degree of accumulation, etc. are determined in consideration of this. In order to transfer the monolayer onto the substrate, in addition to the above-mentioned vertical dipping method, methods such as horizontal deposition method and rotating cylinder method are used. The horizontal deposition method is a method in which the substrate is brought into horizontal contact with the water surface and transferred, and the rotating cylinder method is a method in which a cylindrical substrate is rotated on the water surface to transfer a monomolecular layer onto the surface of the substrate. In the vertical immersion method mentioned above,
When the substrate is lifted out of the water in a direction across the water surface, a monomolecular layer with the first hydrophilic group facing the substrate is formed on the substrate. When the substrate is moved up and down as described above, one monolayer is overlapped with each step. Since the direction of the film-forming molecules is reversed between the pulling process and the dipping process, according to this method, a Y-shaped film is formed in which hydrophilic groups and hydrophilic groups and hydrophobic groups face each other between each layer. On the other hand, the horizontal deposition method is a method in which the substrate is brought into horizontal contact with the water surface and transferred, and a monomolecular layer with hydrophobic groups facing the substrate is formed on the substrate. In this method, there is no change in the direction of the film-forming molecules even if the films are accumulated, and an X-type film is formed in which the hydrophobic groups face the substrate side in all layers. On the other hand, a cumulative film in which the hydrophilic groups in all layers face the substrate side is called a Z-type film. The rotating cylinder method is a method in which a cylindrical substrate is rotated on the water surface to transfer a monomolecular layer onto the surface of the substrate.
The method of transferring a monomolecular layer onto a substrate is not limited to these methods, but when using a large-area substrate,
A method of extruding the substrate from a substrate roll into an aqueous phase may also be used. Furthermore, the directions of the aforementioned hydrophilic groups and hydrophobic groups toward the substrate are in principle, and can be changed by surface treatment of the substrate, etc. When the prepared optical recording medium is irradiated with light that can supply the energy necessary for polymerization, such as gamma rays, X-rays, and ultraviolet rays, according to a certain pattern, polymerization occurs at the irradiated area as shown in the formula. Further, for the diacetylene compound represented by the general formula (), polymerization occurs as shown in the formula (V) by light irradiation. These reactions can occur when the distance between adjacent unsaturated bonds is 4 Å or less, and in a monolayer film or a stacked monolayer film created by the method described above, the reaction occurs when the distance between adjacent unsaturated bonds is 4 Å or less. It is possible between adjacent molecules or between adjacent molecules of a cumulative layer. In addition, after polymerization, depolymerization does not occur even in the dark, and the non-irradiated parts remain monomers, so the first
As shown in the figure, recording is performed according to a certain pattern. The recorded information is read by, for example, irradiation with visible light. That is, the conjugated system of the monomer is destroyed by polymerization, resulting in a change in the absorption wavelength of visible light. Since the maximum absorption wavelength shifts to the lower wavelength side, information can be reproduced by reading changes in the absorption spectrum (Figure 2). Therefore,
In this case, reproduction of information is easier if the conjugated system is longer because the change in the maximum absorption wavelength of the monomer and polymer is greater. For regeneration, in addition to reading changes in absorption spectrum using visible light, it is also possible to read changes in volume during monomerization and after polymerization using the Schilleren method. This method is particularly suitable for molecular films of compounds having a structure that exhibits a large volume change between monomer and post-polymerization. In addition, rather than depositing a monolayer or monolayer stack directly on the substrate,
By forming a photoconductor layer such as ZnO or CdS and forming a monomolecular film or a monomolecular layer stack on top of it, it is also possible to electrically read the difference in absorbance between the monomer and polymer. be. Information is removed by depolymerization by heating, for example at 300-450°C (Figure 3). Optical recording media can be used repeatedly up to about 100 times, although deterioration occurs due to heating to remove information. The substrate on which the monomolecular film or monomolecular layer cumulative film of the photopolymerizable monomer is formed is not particularly limited, but if a surfactant is attached to the surface of the substrate, when the monomolecular layer is transferred from the water surface, the monomolecular film It is necessary to use a substrate with a clean surface because the substrate surface is disturbed and a good monomolecular film or monomolecular layer stack cannot be formed. Examples of substrates that can be used include glass,
Examples include metals such as aluminum, plastics, and ceramics. The monomolecular film or monomolecular layer stack on the substrate is sufficiently strongly fixed and rarely peels or peels off from the substrate. An adhesive layer can also be provided between the molecular layer stacks. Furthermore, the adhesive strength can also be strengthened by selecting the monomolecular layer formation conditions, such as the hydrogen ion concentration of the aqueous phase, the ionic species, or the surface pressure. Providing a protective film on a monomolecular film or a monomolecular layer stack is preferable in order to improve the chemical stability of the monomolecular film or monolayer stack; Depending on selection, a protective film may or may not be provided. EMBODIMENT OF THE INVENTION Below, the Example and the application example of this invention will be shown and it will explain it more specifically. Example 1 A film-forming molecule is a quaternary salt A~ in which an n-octadecanoyl group is introduced onto the pyrazine ring of 2,5-distyrylpyrazine, and the surface is sufficiently clean and hydrophilic while keeping the surface pressure constant. The monomolecular film was transferred onto the substrate by gently raising and lowering the glass substrate with
An optical recording medium with a recording layer composed of 100 monomolecular layers was manufactured. The pyrazine ring side of the produced film is in contact with the substrate. Reference Example 1 The optical recording medium prepared in Example 1 was irradiated with X-rays according to a pattern, polymerized as shown in the formula, and information was recorded. (Peroxide ions are dissolved in the aqueous phase during film formation.) According to this method, optical recording media having 5 to 70 accumulated recording layers are capable of high-density recording on the order of molecular units. Ta. When the recorded information was reproduced using visible light with a wavelength of 420 nm, reproduction was possible with a good S/N ratio. This optical recording medium was heated to 300° C. to erase the information, and after heating, X-ray irradiation was performed again according to the pattern to record information. From the above, the optical recording medium of Example 1 was capable of high-density recording on the order of molecular units and could be used repeatedly. Example 2 Repeating the operation of transferring a monomolecular film onto the same substrate as in Example 1 using Compound B ~ as the film forming molecule, 10,
Monomolecular layer cumulative films of 20, 50, 100, 200, 300, 400, and 500 layers were produced. Reference Example 2 The optical recording medium prepared in Example 2 was irradiated with ultraviolet rays according to a pattern, polymerization occurred at the irradiated areas, and information was recorded. The recorded information was read by measuring the volume change of the monomer and polymer using the Schilleren method, and particularly good readings were possible for films with 10 to 200 layers. The optical recording medium of Example 2 was capable of high-density recording and good reproduction, and could be used repeatedly as in Reference Example 1. Example 3 An optical recording medium was produced in the same manner as in Example 1 using the photopolymerizable monomers shown in Table 1.

[Table] Reference Example 3 Recording was performed on the optical recording medium manufactured in Example 3 using the light shown in Table 2, and reproduction was performed. In each case, high-density recording on the order of molecular units was possible, and moreover, repeated use was possible in the same manner as in Reference Example 1 by heating the medium after recording.

【table】

[Table] Example 4 As a film forming molecule and A monomolecular layer cumulative film was manufactured using the following method. C~ was dissolved in chloroform, the solution was developed in an aqueous phase, and C~ was precipitated in the form of a film. Similarly, D~ was dissolved in chloroform, the solution was developed in a water tank separate from C~, and D~ was precipitated in the form of a film. A glass substrate whose surface is sufficiently clean and hydrophilic while keeping the surface pressure constant is C~
The monomolecular film of C~ was transferred onto the substrate by gently lowering it into a water tank. Next, it was lowered into the water tank of D~, and the monomolecular film of D~ was transferred onto the substrate. This operation was repeated to produce an optical recording medium with a recording layer thickness of 50 to 3000 Å. Reference Example 4 The optical recording medium prepared in Example 4 was irradiated with X-rays according to a pattern to record information. When the recorded information was reproduced using visible light with a wavelength of 420 nm, it was possible to reproduce the information with a good S/N ratio, especially in an optical recording medium with a recording layer thickness of 300 to 3000 Å. This optical recording medium is heated to 350℃ to remove information,
Thereafter, X-ray irradiation was performed again according to the pattern and information was recorded. From the above, the optical recording medium of Example 4 was capable of high-density recording on the order of molecular units, and moreover, could be used repeatedly. Example 5 An optical recording medium was produced in the same manner as in Example 4 using the combinations of photopolymerizable monomers shown in Table 3. Reference Example 5 Recording was performed on the optical recording medium manufactured in Example 5 using the light shown in Table 3, and reproduction was performed. In each case, high-density recording on the order of molecular units was possible, and in addition, repeated use was possible in the same manner as in Reference Example 4 by heating the medium after recording.

【table】

Claims (1)

[Claims] One molecule contains a hydrophilic group, a hydrophobic group, and at least one
A compound for optical recording media consisting of a photopolymerizable monomer having 2 unsaturated bonds. 2. The compound for optical recording media according to claim 1, wherein the photopolymerizable monomer is an olefin monomer having a long-chain alkyl group having 10 to 30 carbon atoms.