JPH0652580A - Manufacture of optical recording medium - Google Patents

Abstract

PURPOSE:To provide a method for efficiently manufacture a low-cost optical recording medium having excellent reliability and durability. CONSTITUTION:A first disk formed of a first board 1 made of transparent organic resin and a first optical recording layer 3 formed at one side face of the board, and a second disk formed of a second board made of transparent organic resin and a second optical recording layer 5 formed on one side face of the second board are so laminated that the first and second layers of the disks are opposed to form a close contact structure between the first and second disks. In order to shut-off invasion of moisture from an exterior and to improve scuffing resistance, outer surfaces of both the first and second disks are coated with hydrophobic composition containing silicone resin, acrylic resin melamine resin or their mixture and cured to form hydrophobic hard coating layers 2.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing an optical recording medium which optically performs at least a reading method, for example, an optical recording medium such as a digital audio disc, a video disc, a memory disc, a magneto-optical disc. Is.

[0002]

2. Description of the Related Art The present situation will be described by taking a memory disk as an example. At present, as a memory disk material, glass, acrylic resin or carbonate resin is a subject for study. By the way, when glass is used as such a disc material, since it has excellent durability including moisture resistance, it has little adverse effect on the recording layer formed on the glass substrate, but on the other hand, it has a large weight. The problem is that it becomes heavy, it breaks easily if dropped by mistake, and the recorded data cannot be restored. Precision processing such as pit information on the glass is relatively complicated and costly. There is.

On the other hand, organic resin materials such as acrylic resins and carbonate resins have the advantages that they are highly flexible and difficult to crack, and are inexpensive, but they are more susceptible to scratching than glass and are more susceptible to humidity and outside air. Due to the influence, there is a problem that the recording layer formed on the surface is easily deteriorated.

[0004]

According to the knowledge of the present inventors, when the cause of deterioration of the recording layer formed on the optical recording medium as described above was studied, the intrusion from the outer surface side of the recording layer occurred. In addition to the water content, the moisture in the outside air that enters through the base material from the back side of the base material (that is, the side that contacts the outside world and the recording layer does not exist) is hydrolyzed in the base material. The present inventors have obtained an unexpected finding that a defect caused by the defect is formed, and that the defect not only deteriorates the substrate but also the recording layer formed on the surface thereof as a result.

The present invention has been made on the basis of the above-mentioned findings, and while maximizing the light weight and low cost of the plastic material constituting the base material of the optical recording medium, the scratch resistance of the medium surface is improved. And an optical recording medium having excellent reliability and durability, which effectively prevents defects caused by hydrolysis caused by moisture that has penetrated into the base material and deterioration of the recording layer due to these defects. It is an object of the present invention to provide a method for efficiently and inexpensively manufacturing.

In order to achieve the above-mentioned object, the method of manufacturing an optical recording medium according to the present invention comprises a first substrate made of a transparent organic resin and a first substrate made of a transparent organic resin when manufacturing an optical recording medium using light for at least a reading method. A first disc comprising a first optical recording layer formed on one side surface of the first substrate;
A second disk made of a transparent organic resin and a second optical recording layer formed on one side surface of the second substrate is used as a first optical recording layer of each disk. The second optical recording layer and the second optical recording layer are laminated so as to face each other to form a sealed structure between the first disk and the second disk, and the outer surface of both the first disk and the second disk is formed. A hydrophobic composition containing a silicone resin, an acrylic resin, a melamine resin, or a mixture thereof is provided on the surface which is in direct contact with the outside world to block the entry of moisture from the outside world and to improve scratch resistance. It is characterized in that a hydrophobic hard coat layer is formed by applying and then curing it.

Further, according to the present invention, when manufacturing an optical recording medium using light for at least a reading method, one surface of the first substrate made of a transparent organic resin is prevented from invading moisture from the outside, and A hydrophobic first hard coat layer is formed by applying a hydrophobic composition containing a silicone resin, an acrylic resin, a melamine resin, or a mixture thereof in order to improve scratch resistance and then curing the composition. And a first side on the other side surface of the first substrate.
In order to form a first disc by providing the optical recording layer of (1), to block ingress of moisture from the outside to one surface of the second substrate made of a transparent organic resin, and to improve scratch resistance. A hydrophobic second composition by applying a hydrophobic composition containing a silicone resin, an acrylic resin, a melamine resin, or a mixture thereof, and then curing the composition.
To form a hard coat layer, and a second optical recording layer formed on the other side surface of the second substrate to form a second disc. The first optical recording layer of each disc. And the second optical recording layer are bonded so as to face each other to form a hermetically sealed structure between the first disk and the second disk.

As described above, in the present invention, two discs on which the optical recording layers are formed are laminated so that the optical recording layers face each other to form a hermetically sealed structure therebetween, and at the same time, the outer surfaces of both discs are separated. Since a hydrophobic hard coat layer is formed on the surface, it is possible to effectively prevent defects caused by hydrolysis caused by moisture entering the substrate from the outside and deterioration of the recording layer due to these defects. In addition, it has an excellent effect in improving the abrasion resistance of the medium surface.

Further, in the present invention, since the hard coat layer made of the hydrophobic composition is formed by a coating method such as spinner or dipping, it is possible to quickly and easily manufacture a reliable optical recording medium. Becomes

The present invention will be described below in detail based on the configuration of the memory disk illustrated in the accompanying drawings.

FIG. 1 is a cross-sectional view of a memory disk taken along the center line, and shows an example in which recording layers are formed on both surfaces of the disk. As shown, the recording layer 3 having the track grooves 5 is formed on the base material 1 made of a thermoplastic resin, while the side of the base material 1 on which the recording layer is not formed and which is in direct contact with the outside world. A hydrophobic hard coat layer 2 is formed on the surface. Further, a similar structure is also arranged on the back side of the disc, and both are joined and integrated through a spacer 4 to form a hermetically sealed structure between both discs. By forming such a sealed structure, it is possible to almost completely block the intrusion of water from between both disks.

As the base material 1, carbonate resin such as allyldiglycol carbonate resin, vinyl chloride resin, acrylic resin such as methyl methacrylate resin, or polyolefin resin can be preferably used.

On the other hand, the hard coat layer 2 in the present invention has hydrophobicity, and the hard coat layer can be formed by adding a substance having a hydrophobic group, in addition to the case where the constituent material itself is a hydrophobic substance. Hydrophobicity can also be imparted. Specifically, silicone resin, acrylic resin,
A composition in which a hydrophobic group is introduced into a hydrophobic resin such as a melamine resin, a copolymer thereof, a mixture thereof, or a resin having hydrophobicity, or a hydrophobic substance is added to impart hydrophobicity to the resin. The thing can also be used as a coating composition.

Further, as the coating composition for the hard coat layer, additional components such as a curing agent, a curing accelerator, and a polymerization initiator can be appropriately added.

The above-mentioned hard coat layer is applied with a coating solution of a predetermined composition by a method such as dipping or a spinner method, and then cured by a curing means such as ultraviolet rays,
This forms a hard coat layer.

FIG. 2 shows the hydrophobic hard coat layer 7 as the base material 6.
It is an example of applying and forming on the surface of
In this case, the recording layer constitutes the recording layer 11 by forming the track groove 9 on the surface of the layer 8 made of, for example, an ultraviolet curable resin.

As described above, in the case of FIG. 1, since a material that can be subjected to tracking processing by injection molding is used, the hard coat layer is formed on only one side of the substrate by the spinner method (on the side in contact with the outside). 2 is an example of the case where the hard coat layer is formed on the surface of the substrate by the dipping method in the case of FIG. 2, and in this case, the tracking processing is performed by using the ultraviolet curable resin layer. This is an example of the case where the recording layer is formed by applying.

In the present invention, a hard coat layer is formed on one of the substrates according to the above-mentioned method, and then a recording layer and the like are formed to form respective disks, which are then laminated together to produce. Good.

As described above, in the present invention, two discs on which the optical recording layers are formed are adhered to each other so that the optical recording layers face each other to form a hermetically sealed structure between them. Since the hydrophobic hard coat layer is formed on the outer surface, defects caused by hydrolysis caused by moisture entering the substrate from the outside and the deterioration of the recording layer due to these defects are effectively prevented. In addition to being able to improve the scratch resistance of the surface of the medium, the manufacturing cost can be reduced as compared with the optical recording medium made of glass, and the long-term reliability comparable to that of glass can be achieved. It is possible to provide a certain optical recording medium. Further, in the present invention, since the hard coat layer made of the hydrophobic composition is formed by a coating method such as spinner or dipping in the present invention, it is possible to quickly and easily manufacture a reliable optical recording medium. It will be possible.

[0020]

EXAMPLES Examples of the present invention will be described below as examples, but the present invention is not limited to the description of these examples. Example 1 A methyl methacrylate resin was processed by an injection molding method,
As shown in FIG. 1, the surface of the disk substrate 1 on which tracking processing has been performed on one surface (pits can be formed at this stage if necessary) on the non-tracking surface (outside) is tetramethylolmethane Traacrylate 5
A coating solution having a composition of 0 part, 30 parts trimethylene glycol dimethacrylate and 3 parts benzoin ether was applied by a spinner. The first two components of the coating liquid composition are hydrophobic resins.

After coating, the composition was cured by an ultraviolet polymerization device to form a hydrophobic hard coat layer 2. Example 2 Vinyl chloride was processed by an injection molding method, and as shown in FIG. 1, one surface was subjected to tracking processing and pit processing.
Further, a prepolymer of a solution consisting of 60 parts of hexamethoxymelamine and 40 parts of 1-4 butanediol was diluted with ethyl cellosolve on the surface of the disk substrate 1 which was not subjected to tracking processing, and this was applied with a spinner. ,
After that, it is cured to give a hydrophobic hard coat layer 2
Was formed. Example 3 20 parts of tetraethoxysilane, 10 parts of γ-glycidoxypropyltrimethoxysilane, 20 parts of isopropyl alcohol, and formic acid (formic acid were added to the surface of a disk processed as shown in FIG. 2 using an allyl diglycol carbonate resin. 90%) 30 parts of a solution was applied by dipping, and then the coating film was heat-cured in a constant temperature layer to form a hydrophobic hard coat layer. The first of the solution components is a substance having hydrophobicity. Example 4 40 parts of detraethoxysilane, 30 parts of γ-methacryloxypropyltrimethoxysilane and 10 parts of methyltrimethoxysilane were formed on the surface of a disk processed using an allyl diglycol carbonate resin as shown in FIG. After being hydrolyzed with 0.05N hydrochloric acid, it was applied by dipping on a solution dissolved in isopropyl alcohol, and then the coating film was heat-cured in a constant temperature bath to form a hydrophobic hard coat layer. Comparative Examples 1 to 3 As comparative examples, those prepared in Examples 1 to 3 in which no hard coat layer was formed on the outer surface of the disk were prepared. Examples 5 to 8 In the medium structure shown in FIGS. 1 and 2, one having only one side (that is, one before joining two discs via the spacer 4) was prepared, and the recording layer of this disc ( Hydrophobic hard coat layers were formed on (tracking processing), and this was used as a test disk. Example 5
The material of the hard coat layer corresponding to No. 8 corresponds to Examples 1 to 4, respectively. Comparative Examples 4 to 6 In the above Examples 5 to 7, the hard coat layer was formed only on the recording layer (tracking surface) side surface of each disc, and the hard coat layer was formed on the outer side surface of the disc. A non-existent disc was prepared and used as a test disc. Test Example The memory disks obtained in Examples 1 to 8 and Comparative Examples 1 to 6 were subjected to a scratch resistance test, a moisture resistance test, and a recording layer deterioration property test. The test results are shown in Table 1 below.

Table 1 Example Scratch resistance Moisture permeability resistance Degradation index Example 1 88% 1.4 2.8 Example 2 80% 2.3 4.6 Example 3 92% 0.6 1.0 Example 4 92% 0.6 1.0 Comparative Example 1 40% 2.2 4.4 Comparative Example 2 25% 3.0 6.0 Comparative Example 3 85% 1.0 2.0 Example 5 88% 1.4 3.1 Example 6 80% 2.3 5.1 Example 7 92% 0.6 1.1 Example 8 92% 0.6 1.1 Comparative Example 4 40% 2.2 4.8 Comparative Example 5 25% 3.0 6.6 Comparative Example 6 85% 1.0 2.2 Test method: (1) Scratch resistance A steel wool of # 000 is loaded with a load of 1 kg / cm ² .
The light transmittance after 10 round trips is measured. (2) Moisture vapor resistance 20 ° C, 70% RH in a constant temperature and humidity chamber, one side of the test piece,
Place a metal box on all other surfaces that does not allow moisture to pass through, put dry KCl in it, and measure the weight change after moisture transmission to measure the permeability of the allyl diglycol carbonate resin substrate without a hard coat layer. Relative value when the weight after wetting is 1. (3) Degradation index The test disk was put in a thermo-hygrostat at 70 ° C. and 90% RH for 500 hours, and the occurrence rate of defects in the recording layer before and after the loading (Defect Error Rate).
Was measured. This is one in which a signal of 3.7 MHz (disk rotation speed 1800 rpm) was recorded on the recording layer and read in the same manner. The value of the deterioration index is a relative value when the defect occurrence rate before introduction into the constant temperature and constant humidity tank is 1.

As can be seen from the above results, according to the present invention, not only the scratch resistance but also the moisture permeation resistance can be improved and the recording layer of the recording layer can be improved by forming the hard coat layer on the outer surface side of the substrate. It is possible to provide an optical recording medium that has excellent deterioration characteristics, is inexpensive, and has high reliability. In the above embodiments, the memory disk has been described as an example, but it is possible to provide an optical recording medium having excellent reliability and durability in a digital audio disk, a video disk, a magneto-optical disk and the like. it can.

[Brief description of drawings]

FIG. 1 is a schematic sectional view of a memory disk according to an embodiment of the present invention.

FIG. 2 is a schematic sectional view of a memory disk according to an embodiment of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Base material 2 Hard coat layer 3 Recording layer 4 Spacer 5 Track groove 6 Base material 7 Hard coat layer 8 Tracking groove (sometimes including signal pit) forming resin layer 9 Track groove 10 Spacer 11 Recording layer

Claims (10)

[Claims] 1. When manufacturing an optical recording medium that uses light for at least a reading method, a first substrate made of a transparent organic resin and a first optical recording layer formed on one side surface of the first substrate. Each of the above-mentioned discs, and a second disc comprising a second substrate made of a transparent organic resin and a second optical recording layer formed on one side surface of the second substrate. The first optical recording layer and the second optical recording layer are laminated so as to face each other to form a hermetically sealed structure between the first disc and the second disc, and the first disc and the second disc Silicone resin, acrylic resin, melamine resin, or a mixture thereof in order to block the ingress of moisture from the outside and to improve the scratch resistance on the both outer surfaces of the disk directly contacting the outside. Apply a hydrophobic composition containing Then and forming a hydrophobic hard coat layer by curing this method of manufacturing an optical recording medium. 2. The method according to claim 1, wherein the hard coat layer is cured by ultraviolet rays. 3. The method according to claim 1, wherein the transparent organic resin forming the substrate is a carbonate resin, a vinyl chloride resin or an acrylic resin. 4. The method according to claim 1, wherein the application of the hydrophobic composition is performed by a spinner. 5. The method according to claim 1, wherein the application of the hydrophobic composition is performed by dipping. 6. When manufacturing an optical recording medium that uses light for at least a reading method, one surface of a first substrate made of a transparent organic resin is prevented from entering moisture from the outside and has scratch resistance. In order to improve the, apply a hydrophobic composition containing a silicone resin, an acrylic resin, a melamine resin or a mixture thereof,
Then, this is cured to form a hydrophobic first hard coat layer, and a first optical recording layer is further provided on the other side surface of the first substrate to form a first disc. A hydrophobic resin containing a silicone resin, an acrylic resin, a melamine resin, or a mixture thereof, is provided on one surface of the second substrate made of an organic resin in order to block ingress of moisture from the outside and to improve scratch resistance. A sexual composition,
Then, this is cured to form a hydrophobic second hard coat layer, and a second optical recording layer is formed on the other side surface of the second substrate to form a second disk. Then, the first optical recording layer and the second optical recording layer of each of the discs are attached to each other so as to face each other.
A method for manufacturing an optical recording medium, characterized in that a closed structure is formed between the optical disc and the disc. 7. The method according to claim 6, wherein the hard coat layer is cured by ultraviolet rays. 8. The method according to claim 6, wherein the transparent organic resin forming the substrate is a carbonate resin, a vinyl chloride resin or an acrylic resin. 9. The method according to claim 6, wherein the application of the hydrophobic composition is performed by a spinner. 10. The method according to claim 6, wherein the application of the hydrophobic composition is performed by dipping.