JPH0481834A - Optically reproducible and information recording medium - Google Patents

Abstract

PURPOSE:To form dot patterns reproducible by a semiconductor laser which radiates light of 780nm wavelength by combining and using a diazonium compd. having >=2 pieces of diazo groups in the molecule and a compd. consisting of naphthols as a coupler as a photosensitive layer. CONSTITUTION:The photosensitive layer before exposing of the optically reproducible and information recording medium formed with dot patterns has the diazonium salt which contain >=2 pieces of diazo groups in the molecules and are selected from the group consisting of formulas I to III (where R1 is -N=N- or -NH-) and the naphthol compd. expressed by formula IV (where R2 and R3 are respectively the same or different and are an alkyl group, halogen atom, nitro group or cyano group) as the coupler. The difference in light reflectivity between exposed parts and unexposed parts at 780nm reproducing wavelength is preferably >=10%. The dot pattern constituting one information unit is preferably of a square shape sized >=5mum and <=30mum in length on one side.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an optically reproduced information recording medium. More specifically,
The present invention relates to an optical reproduction information recording medium manufactured by applying photographic technology.

[Prior Art] In recent years, there has been an increasing demand for recording media that can distribute the same information to a large number of people.
Audio and visual information media such as video tapes, CDs, CDVs, and VDs have come to be used like magazines.

However, with magnetic tapes, video tapes, and the like based on magnetization recording, dubbing takes a long time and is not suitable for mass duplication. Furthermore, magnetic tape and video tape themselves are relatively expensive, making them unsuitable for providing information at low cost. Optically readable information media such as CDs, CDVs, and VDs have similar problems.

In particular, when storing storage media on a route for distributing or transmitting information aimed at the general public, many subscribers, users, etc., it is important to use a simple format that is resistant to handling, dirt, and scratches. Moreover, a large amount of relatively high-density information,
It is required to be able to reproduce quickly and inexpensively.

Therefore, attempts have been made to print digital information on substrates such as paper, thin metal sheets, plastic films, plastic thin sheets, and laminates. With printing, a large amount of relatively high-density information can be reproduced quickly and inexpensively.

[Problems to be Solved by the Invention] However, when it comes to printing, a pattern with a negative side length of 50 μm is the limit, and there is a natural limit to increasing the recording density. Furthermore, when it is desired to configure a medium with a metal reflective film such as AJI, it is impossible or extremely difficult to directly print on the metal due to printing suitability issues. Furthermore, even if it were possible, a new problem would arise in the printing durability of the original printing plate.

To solve this problem, an optical reproduction information recording medium that does not rely on printing has been proposed. The optical reproduction information recording medium has an information recording section on a substrate and is a medium for reading a dot pattern of 30 μm or less with a semiconductor laser at a wavelength of 780 nm. The materials considered for the information recording section were:
This is a diazo film using diazonium salt. Diazonium salt has the property of being decomposed by irradiation with light,
It has the property of producing an azo dye through a coupling reaction with a coupler. To this end, a pattern can be generated by masking, exposing, and then developing. However, when a conventionally used diazonium salt is used, there is no difference in reflectance depending on the pattern at a wavelength of 780 ns, so it cannot be read with a semiconductor laser and cannot be used as an optically reproduced information recording medium.

Therefore, an object of the present invention is to use a semiconductor laser with a wavelength of 780n.
An object of the present invention is to provide an optically reproduced information recording medium that can be reliably reproduced with low temperature.

[Means for Solving the Problems] In order to achieve the above object, the present invention exposes and develops a photosensitive layer formed on a substrate to eliminate the difference in light reflectance between an exposed area and a non-exposed area. In the optical reproduction information recording medium on which a dot pattern has been formed, the photosensitive layer before exposure has at least the following formula (a): (wherein R1 is -N=N- or -NH-) A diazonium salt containing two or more diazo groups in the molecule, selected from the group consisting of: (b) the following general formula (I), (wherein R2 and R3 are each the same or different; , an alkyl group, a halogen atom, a nitro group, or a cyano group).

It is preferable that the difference in light reflectance between the exposed area and the non-exposed area at a reproduction wavelength of 780 nm is 10% or more.

The dot pattern constituting one information unit is preferably a square with a side length of 5 μm or more and 30 μm or less.

[Operations] As described above, in the present invention, the dot pattern is formed by photosensitive technology, so it is possible to form a finer dot pattern than by printing technology. Therefore, the information recording density per unit area of the substrate can be significantly increased.

Furthermore, since there is no mechanical contact with the substrate as in printing, there is no wear and tear on the exposure mask, and it is possible to semi-permanently reproduce a medium of the same quality.

Noazonium salt, which has been conventionally used as a photosensitizer, can be used together with a coupler to form a pattern consisting of dots with a side length of 30 μm or less by exposure and development. When a semiconductor laser is used as a light source for optical reproduction, the difference in light reflectance at 780 nm must be 10% or more between the foggy area and the non-exposed area. However, since conventional diazonium salt photosensitizers have only one diazonium group in the molecule, 780n-
Since there is no difference in light reflectance depending on the pattern, it was not possible to read it with a semiconductor laser.

Since the diazonium salt of the present invention has two or more diazo groups in the molecule and uses naphthols as a coupler, the azo compound produced by the coupling reaction has a π-π transition due to its structure. The excitation energy decreases,
The light absorption at 780n- is increased and it can be used as a photosensitive layer of an optically reproduced information recording medium.

The size of the optically reproduced information recording medium of the present invention is not particularly limited. Therefore, an appropriate size may be selected depending on the use and/or purpose. - By way of example, the media of the invention can be postcard sized. In other words, the size of a regular postcard issued by the Minister of Posts and Telecommunications as stipulated in Article 12 of Ministerial Ordinance No. 34 (Postal Regulations) is 14.8 cm in height and 1001 cm in width.
The size of a postcard or a privately made regular postcard as defined in Article 13: the long side is 14 cm or more and within 15 cm, and the short side is 9 cm or more and within 10°7 cm. These can currently be mailed for 41 yen.

The light source itself used for optical reproduction is not particularly limited.

However, it is generally preferable to use a semiconductor laser as a light source. The wavelength of the reproduction light is preferably around 780 nm.

The dot pattern is formed on the substrate using photolithographic techniques. That is, a photosensitive layer made of a resin binder containing a diazonium salt, a dye coupler, an oxidation stabilizer, etc. is applied onto a substrate, and exposed through a mask. The diazonium salt in the exposed area decomposes and becomes an inert substance that does not react with the coupler, while the diazonium salt in the unexposed area reacts with the coupler in ammonia gas during development to form an azo dye and color. do. Thus, the exposed areas are transparent and the unexposed areas are strongly colored and absorb light. In this way, a photoreproducible dot pattern can be formed.

In the diazonium salt that can be used in the present invention, for example, a halogen atom such as F or Cλ is suitable as a counter ion for the diazo cation represented by ZnCλ2,
Double salts can also be formed with Lewis acids such as B F 4 or PFs.

The coupler used in combination with the diazonium salt is, for example, a compound containing two or more diazo groups in the molecule, as shown below. Structural Formulas of (1) to (3) % Formula % As shown in the above structural formulas, a naphthol compound is used as Kabra. These compounds do not have absorption characteristics at the light peak absorption portion of the azo compound produced after the coupling reaction and at a wavelength of 780 nm, and do not change color even under alkaline conditions or over time. Moreover, the coupling rate is high in a specific pH range, and the photolysis of the diazonium salt is not hindered.

It is also necessary that it be easily soluble in water or an organic solvent such as DMF (N,N-dimethylformamide).

If necessary, a metal reflective film may be provided on the substrate, and a photosensitive layer may be formed thereon. By providing a metal reflective film, it is possible to increase the difference in light reflectance between the transparent exposed portion and the colored non-exposed portion. As a metal reflective film,
Mainly Aβ or AJ gold alloys are used, but N M g F
An optical interference type reflective film made of a dielectric film such as No. 2 can also be used. The metal reflective film can be formed by a conventional method such as a vapor deposition method or lamination.

When a metal reflective film is placed on a substrate with a diazo photosensitive layer,
When the photosensitive layer is exposed to light, halation may occur and the outline of the formed dot pattern may become unclear.

The ultraviolet light used during exposure is usually close to parallel light, but it also includes some obliquely incident light, and the unevenness of the surface of the photosensitive film itself causes diffuse reflection, which can cause the pattern boundaries of the mask to be distorted. This causes the exposure to wrap around the area. This wraparound is not a problem if the reflectance of ultraviolet light on the substrate side (for example, the entire lower part of the photosensitive layer) is low, but if it is high, that is, in a typical example, directly below the photosensitive layer. When a reflective film such as Al is provided in the photosensitive layer, the reflected light undergoes multiple reflections with high intensity between the reflective film and the photosensitive layer, exposing a considerable area of the photosensitive layer covered by the mask. Naturally, this effect becomes larger as the pattern size becomes smaller.

As a solution to this problem, an antihalation layer that absorbs ultraviolet light can be provided below the photosensitive layer in order to reduce the reflectance on the substrate side. However, since a semiconductor laser is used to reproduce information, it is necessary to be transparent at the wavelength of the semiconductor laser used, that is, to have sufficiently low absorption.

Specifically, the antihalation layer is formed, for example, by coating a resin with a magenta-colored diazo pigment (dye) dispersed therein.

The antihalation film is preferably placed directly under the photosensitive layer, but Aλ
When a reflective film such as the above is located on the opposite side of the photosensitive layer across the substrate, it may be possible to provide an antihalation film between the substrate and the reflective film depending on the exposure conditions.

In addition, when a reflective film such as A1 is provided on the surface of the substrate opposite to the photosensitive layer after exposing a medium on which a diazo photosensitive layer is provided, it is especially necessary to provide a halation prevention film. There isn't. The Halley/Con prevention film is only necessary in cases where the AJ reflective film is already provided on the substrate.

The light reproducing method in the present invention utilizes the difference in reflectance at the wavelength of the reproduced light between the exposed and non-exposed areas that form the dot pattern of the medium, and measures the intensity of the reflected light with a photodetector such as a photodiode. The information is then read out by converting this into an electrical signal. The difference in light reflectance at the reproduction light wavelength between the exposed area and the unexposed area must be 10% or more. If the difference in light reflectance is less than 10%, reading information becomes uncertain. In this specification, the term "light reflectance" refers to the ratio of the amount of reflected light to the amount of incident light obtained by a method in which the light is vertically incident on the medium at a solid angle of 10 degrees and the reflected light is detected in the same vertical direction within a solid angle of 10 degrees. means.

In addition to paper, substrates used in the medium of the present invention include polymer films such as polyimide and polyethylene terephthalate, metal foils (for example, aluminum foil, iron foil, stainless steel foil, etc.),
Glass and ceramics. Paper or plastic films are preferred. The color of the paper substrate is not particularly limited. It may be colored white, black or other colors. The plastic film may be transparent, or may be colored black, white, or other colors. The light reflecting film or light absorbing film described above may be used as appropriate depending on the characteristics of the substrate.

[Example code] Hereinafter, the present invention will be explained in more detail with reference to Examples.

Example 1 - Chloride/zinc chloride double salt of a diazo cation represented by the above structural formula (2) as a diazonium salt 0. 15 g, and 0.18 g of the compound represented by the above structural formula (a) as a coupler.
g is dissolved in DMF1λ, and a binder, an antioxidant, etc. are added to this solution to prepare a photosensitive layer coating solution.

Then, as shown in FIG. 1, A
The above coating liquid was applied onto a λ thin film 2 formed by a 1000 vacuum evaporation method to form a photosensitive film 3 for reproduction. This is exposed to ultraviolet rays (UV) 5 through a photomask 4 on which an information pattern is formed, and then a second
As shown in the figure, development was carried out in an ammonia atmosphere 6.

As a result, the reaction shown in (i) below occurs in the exposed area, and the reaction shown in (11) below occurs in the non-exposed area, and the exposed area becomes mostly transparent.
Unexposed areas develop color. In this way, as shown in FIG. 3, there is a difference in light reflectance between the exposed area 7 and the non-exposed area 8, so that optical reproduction allows the dot pattern 9 to be read with a semiconductor laser having a wavelength of 780 tv. An information recording medium 10 is obtained.

(i) (II) The molar extinction coefficient of this medium at 780 nm is 410λ
/ Cabinet o1 ・It was cll.

Shigoken 2 A chloride/zinc chloride iio, i6g of a noashcation represented by the above structural formula (3) as a diazonium salt, and 0.21 g of a compound shown by the above structural formula (b) as a coupler.
is dissolved in DMFiλ, and a binder, an antioxidant, etc. are added to this solution to prepare a photosensitive layer coating solution. And polyethylene terephthalate (PET) with a thickness of 100 μm
The above coating solution was applied onto a thin film of A-2 formed by 1000 vacuum evaporation method on film 2 to form a photosensitive film for reproduction. This was exposed to ultraviolet (UV) light through a photomask on which an information pattern was formed, and then developed in an ammonia atmosphere.

As a result, the reaction shown in (i) below occurs in the exposed area, and the reaction shown in (1v) below occurs in the non-exposed area, and the exposed area becomes mostly transparent and non-exposed. The exposed area develops color. In this way, there is a difference in light reflectance between the exposed area and the non-exposed area, so that an optically reproducible information recording medium whose dot pattern can be read with a semiconductor laser having a wavelength of 780 nm is obtained.

UN) (1v) The molar extinction coefficient of this medium at 780n is 3000
J2/mat ・It was C garden.

1 effect example - Dissolve 0.15 g of a compound represented by the following structural formula (A) as a diazonium salt and 0.20 g of a compound represented by the following structural formula (B) as a diazonium salt in DMF lλ,
A binder and an antioxidant are added to this solution to prepare a photosensitive layer coating solution. Then, the coating solution was applied onto a polyethylene terephthalate (PET) film having a thickness of 100 μm, on which an AJt thin film was formed by 1000 vacuum evaporation, to form a photosensitive film for reproduction. This is then passed through a photomask with an information pattern formed on it.
Exposure to ultraviolet (UV) light followed by development in an ammonia atmosphere. In this way, an optically reproduced information recording medium having a dot pattern consisting of transparent exposed areas and colored non-exposed areas is obtained.

0.25 g of the azo compound formed in the non-exposed area of each medium of Example 1, Example 2 and Comparative Example 1 was added to DMF lλ
The light absorption spectrum of the resulting solution was measured using a spectrophotometer. The measurement results are shown in Figure 4.

As is clear from comparing the light absorption spectra of each medium shown in FIG. 4, each medium of Example 1 and Example 2 according to the present invention has a low transmittance (T%) at a wavelength of around 780 nm. Although it is possible to distinguish between transparent exposed areas and colored unexposed areas, the medium of the comparative example has a transmittance of about 100% at a wavelength of 780 n-, making it impossible to distinguish between exposed areas and unexposed areas. In other words, optical reproduction of the dot pattern becomes impossible.

The structure of the dot pattern 9 formed on the substrate 1-[- is as follows:
As shown in FIG. 5, corresponding to the digital information to be transmitted, there is a square unit light-absorbing part (i.e., a non-exposed coloring part) 8 of a predetermined size, and a unit light-reflecting part (1) of a similar size (
In other words, it is an array of linear spatial patterns that constitute specific data by combining exposed transparent parts) 7, and the information corresponding to the digital value "1" or the unit light absorption part 8 is on the information track. to be formed (to exist)
The presence of the unit light reflection portion 7 expresses information corresponding to the digital value 0''.The relationship between the unit light absorption portion 8 and the medium light reflection portion 7 is '1'', 0
0" may have the opposite relationship. In addition, consecutive "1"
When data exists, the unit light absorbing portion 8 is formed as a continuous, integral line.

The optical reproduction information recording medium of the present invention converts and records image information and audio information into a digital dot pattern, and the size of the dot pattern is 30 μm or less on the negative side, preferably in the range of about 5 to 30 μm. It has been realized. If the information recording area is 8 x 12.8 cm, approximately 1.4 to 5.7 megabytes of information can be stored. RGB with 256x256 pixels
7 to 28 images with 8 bits of information for each image, 8kHz 1
The 8-bit sampling audio information corresponds to a pattern of 2.9 to 11.9 do. In addition, if desired, image compression,
It is also possible to add an error correction code.

The optical reproduction method uses the difference in light reflectance at the reproduction light wavelength between the exposed area of the medium and the 4L exposed area, and converts the reflected light intensity into an electrical signal with a photodetector such as a photodiode and reads it out. can. An example of a device that can be used for this purpose is disclosed in Japanese Patent Application No. 63-093139.

The optical reproduction information recording medium of the present invention has a positioning stripe pattern adjacent to the data area consisting of the photosensitive dot pattern described above, in order to prevent misloading or mistracking of the information recording medium. It can also be provided by a photosensitive technique similar to that used for patterns. Such a positioning stripe pattern is disclosed in detail in Japanese Patent Application No. 63-093138.

In addition, in order to protect the dot pattern formed by photosensitive technology, protective measures such as those disclosed in U.S. Pat. No. 83-065834 and U.S. Pat. You can also do it.

[Effects of the Invention] As explained above, according to the present invention, by using a combination of a diazonium compound having two or more diazo groups in the molecule and a compound consisting of naphthols as a cabra, it is possible to emit light with a wavelength of 780 nm. A reproducible dot pattern can be formed by emitting a semiconductor laser.

[Brief explanation of the drawing]

FIG. 1 is a schematic cross-sectional view showing the exposure state of the medium of the present invention, FIG. 2 is a schematic cross-sectional view showing the state of developing the medium exposed in FIG. 1, and FIG. FIG. 4 is a schematic cross-sectional view of the medium of the present invention obtained by the development treatment of Example 1, Example 2, and Comparative Example 1. FIG. FIG. 5 is a plan view of the dot pattern formed on the substrate. 1...Substrate, 2..., l thin film. 3... Photosensitive layer, 4... Photomask. 5... Ultraviolet rays, 6... Ammonia atmosphere. 7...Exposed transparent part, 8...Non-exposed colored part.

Claims (6)

[Claims] (1) In an optical reproduction information recording medium in which a dot pattern is formed by exposing and developing a photosensitive layer formed on a substrate to create a difference in light reflectance between exposed and non-exposed areas, before exposure The photosensitive layer has at least the following formula: ▲There are mathematical formulas, chemical formulas, tables, etc.▼...(1), ▲There are mathematical formulas, chemical formulas, tables, etc.▼...(2), ▲Mathematical formulas, There are chemical formulas, tables, etc. ▼... (3) Containing two or more diazo groups in the molecule, selected from the group consisting of (in the formula, R_1 is -N=N- or -NH-) Diazonium salt and (b) The following general formula (I), ▲There are mathematical formulas, chemical formulas, tables, etc.▼(I) (In the formula, R_2 and R_3 are each the same or different, and are an alkyl group, a halogen 1. An optical reproduction information recording medium comprising a coupler made of a naphthol compound represented by an atom, a nitro group, or a cyano group. (2) The difference in light reflectance between exposed and non-exposed areas is 78
2. The optically reproduced information recording medium according to claim 1, characterized in that it is 10% or more at a reproduction light wavelength of 0 nm. (3) The optically reproduced information recording medium according to claim 1 or 2, further comprising a light reflecting film between the substrate and the photosensitive layer. (4) The optically reproduced information recording medium according to claim 1 or 2, characterized in that a light reflecting film is provided on the dot pattern forming side of the substrate or the opposite side thereof. (5) The optical reproduction information recording medium according to claim 3 or 4, wherein the light reflective film is a metal reflective film or an optical interference type reflective film. (6) A light reflective film is provided on the substrate, and an antihalation film is further provided between the light reflective film and the photosensitive layer, between the substrate and the photosensitive layer, or between the substrate and the light reflective film. The optical reproduction information recording medium according to claim 3 or 4, characterized in that: