JPS5987633A - Information recording medium - Google Patents

Abstract

PURPOSE:To protect an optical disk from dust and a scratch by coating the surface of each substrate for the disk with a composition contg. thermoplastic resin which is cured under active energy beams and has no unsatd. double bond and a compound having a double bond and by irradiating active energy beams to form a protective layer. CONSTITUTION:A substrate is placed opposite to a stamper subjected to metallizing after forming unevenness for information with a photoresist or the like while leaving a slight interval, and a photoresist 2 is injected into the gap and cured by iradiating active energy beams such as ultraviolet rays or electron beams from the side of the substrate. The cured photoresist 2 is stripped from the stamper, and a metal such as Al is vapor-deposited to form a specular information surface 3. The thickness of the deposited layer is usually about 500Angstrom . The surface 3 is then coated with a composition so that a protective layer 4 of about 3mum thicknes is formed, and the composition is cured by irradiating active energy beams. When the composition contains a solvent, active energy beams are irradiated after drying the composition at about 50-100 deg.C for about 5min. A protective layer 5 is similarly formed on the surface of the substrate 1.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an information recording medium (hereinafter referred to as a disk) suitable for video disks, digital audio disks, etc., and particularly to information recording media (hereinafter referred to as disks) suitable for video disks, digital audio disks, etc. Regarding a disk in a so-called optical disk system, the purpose is to protect the disk from dust and scratches by forming a hard transparent thin film on the surface of the disk.

Conventionally, recesses are formed using photoresist on a disk substrate made of methacrylic resin, vinyl chloride resin, polycarbonate resin, etc., and a thin film of Bi (bismuth) or the like is formed on top of this to form information signals in the form of geometric changes. A so-called optical optical disk system is known in which recording is performed and pickup is performed using a laser beam. After that, metallization treatments such as aluminum vapor deposition began to be applied to the information surface of the disk as a treatment for reflecting laser light. The disc manufactured as described above can be played on only one side of the disc, but it is also known that it can be played on both sides, and after the metallization treatment described above, two discs with the information side inside Glue and paste. When playing a disc, whether it is a single-sided playable disc or a double-sided playable disc, the laser light normally enters from the surface of the base material opposite to the information surface, is reflected by the information surface, and is modulated. After that, the light is emitted from the surface of the base material again. At this time, if there are scratches or stains on the surface of the base material, which is the opposite side to the information side, the laser light will be scattered due to the scratches or stains, causing omissions or noise in the reproduced signal. Also known is a method in which information signals are recorded by forming a thin film of a low melting point metal such as Te (tellurium) on a base material and drilling holes with a diameter of about 1 μm by irradiating the film with laser light.

In the above-mentioned discs, the base materials, such as methacrylic resin, vinyl chloride resin, and polycarbonate resin, have the disadvantage that they are relatively easily scratched, and dirt easily adheres to them due to static electricity. However, when the metal of the information surface comes into direct contact with air, the metal is oxidized due to the influence of oxygen and moisture in the air, and the reflectance is reduced.

In order to improve these drawbacks, single-sided playable discs are provided with a protective layer on both the information side and the surface of the base material that is the opposite side of the information side, and double-sided playable discs are provided with a protective layer on both sides of the base material. It has been proposed to provide a protective layer on both sides.

Various methods have been proposed for this protective layer, such as a method in which a thermoplastic resin is applied by spin coating to form a protective layer, a method in which a radiation (active energy ray) curable resin is applied, and the protective layer is cured by radiation. A method of bonding a transparent film with an adhesive to form a bonding layer is known. However, although a protective layer using a thermoplastic resin has good adhesion to a substrate or a metallized surface such as aluminum vapor deposition and moisture permeability, it has some problems in abrasion resistance.

A protective layer made of a radiation-curable resin has excellent abrasion resistance and scratch resistance, but has poor adhesion and moisture permeability to the base material and metallized surface, especially to the metallized surface.

Furthermore, when a transparent film is bonded with an adhesive, the number of steps increases, leading to an increase in cost.6 The present invention relates to a disk that can address the above-mentioned problems. That is, an information signal is recorded in the form of a geometric change on a base material, and the information surface and/or the surface of the base material opposite to the information surface does not have active energy ray-curable unsaturated double bonds. An information recording medium is provided with a composition containing a thermoplastic resin and a compound having an active energy ray-curable unsaturated double bond, and is formed by irradiating the composition with active energy rays to form a protective layer. A composition containing 10 to 90% by weight of a thermoplastic resin having no unsaturated double bonds and 90 to 10% by weight of a compound having active energy ray-curable unsaturated double bonds is excellent as a protective layer for a disc. This is what we discovered.

The above composition has good adhesion to base materials such as methacrylic resin, vinyl chloride resin, polycarbonate resin, etc.
It also has good adhesion to metal surfaces such as aluminum evaporation. Further, the protective film of the above composition has sufficient hardness, excellent abrasion resistance, scratch resistance, and transparency, and has low moisture permeability.

Thermoplastic resins used in the present invention include polyvinyl chloride, vinyl chloride-vinyl acetate copolymer, saponified vinyl chloride-vinyl acetate copolymer, vinyl chloride-vinyl acetate-maleic anhydride copolymer, and polyvinyl chloride-vinyl acetate copolymer. Vinyl acetate, acetylcellulose, polyethylene terephthalate, polyimide, polyurethane, polyvinyl butyral, polyvinyl formal, polyhinyl alcohol, polyvinylidene chloride, polyvinylpyrrolidone, acrylic resin, polyvinyl acrylamide, polycarbonate, nylon, polyethylene, polypropylene, polybutene, polyvinylidene fluoride , polytrifluorochloroethylene, etc.

The compound having an active energy ray-curable unsaturated double bond may be a monomer, an oligomer, or a prepolymer, or two or more of them may be used. The active energy ray-curable unsaturated double bond may be any double bond such as an acrylic double bond or an allylic double bond that can be cured by 11+, ultraviolet rays, or electron beam irradiation. Monomers include (meth)acrylic acid, ethyl (meth)acrylate, butyl (meth)acrylate,
Ethylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, 1,6-hexane gelicoldi(meth)acrylate, trimethylolpropane tri(meth)acrylate, styrene, methylstyrene, acrylamide, glycidyl(meth)acrylate, These include 2-hydroxylethyl (meth)acrylate, maleic anhydride, diallyl maleate, diallyl adipate, and the like. Examples of the oligomer or prepolymer include epoxy acrylate, urethane acrylate, and unsaturated polyester.

The composition ratio of the thermoplastic resin and the compound having an active energy ray-curable unsaturated double bond is 1° to 90:90.
It is preferably from 10 to 10 (% by weight). If the thermoplastic resin is too small, the adhesiveness and moisture permeability will be poor, and if it is too large, the abrasion resistance will be poor.

The protective layer according to the present invention is formed by curing with active energy rays such as ultraviolet rays and electron beams. When ultraviolet rays are used, one type of photopolymerized softyl ether, diphenyl sulfide, triethylamine, etc. is added to the composition. Or add two or more kinds. In addition, when irradiating with an electron beam, it is not necessarily necessary to use a plating.

Furthermore, additives such as a leveling agent and a silane cuffing agent may be used in the composition as needed.Also, the composition may be of a solvent-free type or may contain a solvent. .

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

The drawings are merely one embodiment of the present invention, and the present invention is not limited to the embodiments shown in the drawings.

FIG. 1 is a partial sectional view of a disk showing an example of single-sided playback, and FIG. 2 is a partial sectional view of a disk showing an example of double-sided playback.

1 indicates a base material such as polycarbonate resin or methacrylic resin. Regarding the formation of the information surface, for example, uneven information is formed in advance using photoresist, etc., and then the base material is placed on a metallized stamper (mold) with a slight gap. , inject photoresist into this space,
Active energy rays such as ultraviolet rays and electron beams are irradiated from the base material side to harden the photoresist 2 and peel it off from the stamper. A metal such as aluminum is deposited on the hardened photoresist (2) surface to form an information surface 3 which is a reflective surface. The thickness of this vapor-deposited layer may normally be about 500 Å (angstroms), and the composition that will become the protective layer 4 is applied onto this vapor-deposited layer to a thickness of about 3 μm.

Next, it is cured by irradiation with active energy rays.

In addition, in systems where the composition contains a solvent, the temperature is between 50°C and 100°C.
After drying it in an oven at about ℃ for about 1 to 5 minutes,
Irradiate with active energy rays. A protective layer 5 is similarly formed on the surface of the base material 1 opposite to the information surface 3.

In order to shorten the process, when the composition is coated on both sides, the protective layers 4.5 on both sides may be cured by one activation energy ray irradiation. In addition, in the case of single-sided playback shown in Figure 1, normally,
Information is read from the protective layer 5 side.

In the case of Fig. 2, the information side 3 of the two disc substrates is glued (
Paste in step 7). Note that the formation of the protective layer 6 on the base material 1 is as follows:
This is before or after the bonding process using the adhesive (7).

The present invention will be explained below with reference to Examples. In the examples, "parts" indicate parts by weight.

Example 1 Aluminum 1500A (Angstrom) thick was applied to the uneven surface of a polycarbonate resin disk (2 squares thick) on which geometric changes (irregularities) were formed on the surface using photoresist. 60 parts of the following active energy ray-curable composition Vinyrite VMCH (vinyl-vinyl acetate copolymer manufactured by Union Carbide Co., USA) Aroex M-7100 (Toa Co., Ltd.) 35 parts A-TMP (trimethylolpropane triacrylate manufactured by Kyoeisha Yushi Kagaku ■) 5 parts xylene
150 parts methyl isobutyl ketone
150 parts Sequal BEE (benzoin ethyl ether manufactured by Seiko Kagaku ■)
3 parts were dried with a bar coater to a film thickness of 5 μm.
It was coated so that it looked like this and dried in an oven at 80°C for 5 minutes.

Then, it was cured by irradiating it with a 2KW ultraviolet lamp at a distance of 12 crn for 5 seconds. A protective layer was similarly formed on the base material surface forming the opposite surface to the information surface.

Example 2 A disk was produced in the same manner as in Example 1, except that the following active energy ray-curable composition was used.

S-LEC BL-3 (polyvinyl butyral manufactured by Water Chemical ■) 60
Part DPHA (Dipentaerythritol hexaacrylate manufactured by Nippon Kayaku ■) 35 parts A-TMP S part Seiqual EEE 3 parts Ethyl cellosolve
ioo part isopropyl alcohol
100 parts Methyl isobutyl ketone 100 parts Example 3 A disk was produced in the same manner as in Example 1 except that the following active energy ray-curable composition was used.

Eslec BL-360 Part 1 Jvithane 788 (urethane acrylate oligomer manufactured by Thiokol, USA) 35 parts A
-TMP S-bu Sake All E
EE 5 parts ethyl cellosolve
100 parts isopropyl alcohol
100 parts Methyl in butyl ketone 100
Part Example 4 In the active energy ray-curable composition of Example 1, 7 enoxy resin PKHH (
Example 1 except that a material (manufactured by Union Carbide Company, USA) was used.
A disk was prepared in the same manner as above.

Comparative Example 1 Aroex M7100 95 parts A- as active energy ray curable composition
TMPS part Sequal B E E 1 part methyl isobutyl ketone 150 parts xylene
A disk was produced in the same manner as in Example 1 except that 150 parts were used.

Comparative tests shown in Table 1 were conducted using the disks produced in Examples 1 to 4 and Comparative Example 1.

The results are shown in Table 1.

Table 1 ~( M. 1← Rin

[Brief explanation of the drawing]

FIG. 1 is a partial sectional view of a disk showing an example of single-sided playback, and FIG. 2 is a partial sectional view of a disk showing an example of double-sided playback. Symbols in the figure 1 - Base material, 2 - 7 Otoresist, 3 - Information surface, 4.5.6 - Protective layer, 7 - Adhesive Patent applicant Toyo Ink Mfg. Co., Ltd. ¥1

Claims (1)

[Claims] 1. Information signals are recorded in the form of geometric changes on a substrate, and the information surface and/or the surface of the substrate opposite to the information surface is coated with active energy ray-curable unsaturated An information record comprising a composition containing a thermoplastic resin having no double bonds and a compound having an active energy ray-curable unsaturated double bond, and irradiating the composition with active energy rays to form a protective layer. Medium. 2 10 to 90% by weight of a thermoplastic resin having no active energy ray-curable unsaturated double bond and 90 to 1% of a compound having an active energy ray curable unsaturated double bond
The information recording medium according to claim 1, which is a composition containing 0% by weight.