KR19990068997A - Method of manufacturing recordable optical recording medium - Google Patents

Abstract

Disclosed is a method of manufacturing a recordable optical recording medium. The recording layer and the reflective layer are sequentially formed on the substrate on which the guide bone is formed, and a protective layer is formed on the reflective layer by curing with a predetermined thickness by spin coating with an organic material having a viscosity of about 200 to 1000 mPass. To prepare. According to the method of manufacturing a write-once optical recording medium, the permeability to the recording layer is reduced in the film formation process by the protective layer resin having a suitable viscosity thereon, even for aluminum which is a low-cost reflective layer material, thereby reducing the recording layer damage. As a result, recording characteristics can be improved and manufacturing costs can be reduced.

Description

Method of manufacturing recordable optical recording medium

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a write-once optical recording medium, and more particularly, to write-once optical which prevents impurity input into the recording layer in the film formation process of layers to be sequentially stacked on the recording layer, thereby preventing degradation of recording characteristics. A method for manufacturing a recording medium.

Optical recording media are high density recording media having a smaller area per unit recording than magnetic recording media, and are replacing magnetic recording media. Such recording media are read only memory (ROM) type that only plays recorded information, write once read many (WORM) type, and erasable which can be erased and rewritten after recording. )

In recent years, with the continuous increase in the amount of processing information, the development of DVD (Digital Video Disc), which is a high-density optical recording medium employing short wavelengths, is actively underway. DVDs can be classified into play-only DVD-ROMs, record-erasable DVD-RAMs (DVD-Erasables), recordable write-once DVD-Rs, and some of them are commercially available. It wasn't far from commercialization.

Among such optical recording media, write-once optical discs capable of recording once are generally adopting a recording method using a dye transformation by laser. A recording layer, a reflective layer and a protective layer mainly composed of organic pigments are sequentially formed on a substrate. have. In the write-once optical recording medium, the substrate is heated and deformed by absorbing a laser in the recording layer during recording, thereby generating heat. Accordingly, the reflectance before and after recording is changed to reproduce the recording signal.

As the demand demand of recordable optical recording media increases, the price of disks is being accelerated, and various studies are being conducted to reduce the manufacturing cost.

CD-R, which is a recordable optical recording medium, forms a reflective layer made of gold (AU) having high reflectivity for compatibility with CD, which is a ROM type medium, and is low for 780nm band recording laser light. There is a problem in that the manufacturing cost is high by using a cyanine or phathalocyanine-based expensive dye having a water absorption as a material of the recording layer.

In the manufacturing process of CD-R, which is a recordable optical recording medium, fine holes are present in forming a reflective layer by sputtering of gold, silver, etc., and a protective layer is formed by applying a photocurable coating solution on the reflective film. In this process, the coating solution penetrates into the recording layer through the hole, thereby causing a problem of damage to the pigment forming the recording layer. The damage of the recording layer due to the absorption of the protective layer forming material into the recording layer lowers the recording capability.

In order to improve this, U.S. Patent No. 5,422,226 discloses a method of controlling the thickness and shrinkage rate of a protective layer stacked on a gold (AU) reflective layer, and U.S. Patent No. 4,990,388 discloses a method for controlling a recording layer and a reflective layer. A method of protecting a recording layer from damage by providing a barrier layer such as an epoxy resin has been disclosed, but they also use gold as a reflective layer material and have a problem of failing to lower manufacturing costs because a separate barrier layer must be introduced. have.

On the other hand, an aluminum material whose material cost is lower than gold has affinity with a coating solution for a photocurable protective layer having a viscosity of about 80 mPass, which is commonly used. It is not used as a material for applying the reflective layer because it increases the absorption rate of the coating solution to the recording layer through the holes formed in the reflective layer.

The present invention was devised to improve the above problems, and to increase the molecular weight of the curable resin for the protective layer so as to have a lower characteristic of the permeability to the hole formed in the reflective layer formed of aluminum material to reduce the fluidity and to the pigment of the recording layer It is an object of the present invention to provide a method of manufacturing a write-once optical recording medium capable of lowering the melting capacity to suppress damage to the recording layer as well as lowering the manufacturing cost.

1 is a cross-sectional view of an optical recording medium to which the method for manufacturing a write-once optical recording medium of the present invention is applied.

<Description of Symbols for Major Parts of Drawings>

10: substrate 11: guide bone

20: recording layer 30: reflective layer

40: protective layer

In order to achieve the above object, a method of manufacturing a write-once optical recording medium according to the present invention includes a substrate in which a guide bone is formed, and a recording layer, a reflective layer, and a protective layer are sequentially stacked on the substrate, and can be recorded only once. In the method of manufacturing a write-once optical recording medium, the protective layer is formed of an organic material having a viscosity of about 200 to 1000 mPass by curing on the reflective layer to a predetermined thickness by spin coating.

The protective layer is preferably formed of UV curable resin (UV-curable), acrylic resin, polycarbonate resin, polysiloxane resin as a main component.

Hereinafter, a method of manufacturing a recordable optical recording medium according to the present invention will be described in detail with reference to the accompanying drawings.

1 is a cross-sectional view showing a recordable optical recording medium according to the present invention.

Referring to the drawing, the optical recording medium includes a substrate 10 and a recording layer 20, a reflective layer 30, and a protective layer 40 sequentially stacked on the substrate 10.

The substrate 10 is made of a material that maintains transparency to the laser light, has excellent impact strength, and can be easily expanded and deformed at a temperature of 80 to 200 ° C. Materials satisfying these characteristics include polycarbonate, polymethyl methacrylate (PMAA), epoxy resin, polyester, and amorphous polyolefin (APO). It is preferable that glass transition temperature (Tg) is 100-200 degreeC. In addition, the guide bone 11 for guiding the incident laser light at the time of recording or reproduction is formed on the surface of the substrate 10, and the depth d1 is preferably 50 to 300 nm. If the depth of the guide bone 11 is less than 50 nm, the reflectance is greatly increased due to the expansion of the substrate 10 after recording, and thus the noise of the recording signal increases. On the other hand, if the depth of the guide bone 11 exceeds 300 nm, the reflective layer 30 ) Can be deeply formed so that the reflectance is reduced, and it is difficult to obtain a uniform reflective layer 30 by spin coating when forming the reflective layer 30. Further, it is appropriate that the half width of the bone, that is, the width in the horizontal direction at the middle height from the bottom surface of the guide bone 11 to the top thereof is 200 to 550 nm. If the median width of the bone is less than 200nm, it is difficult to obtain high emission rate, and if it is more than 550nm, tracking problems may occur. In the drawing, the region 12 in which the depth of the guide bone 11 is relatively low is due to deformation due to thermal expansion during the recording process.

As a material of the recording layer 20, a dye or an organic material having a large refractive index is used.

The dye applied to the recording layer 20 is an organic substance that is easily deformed or decomposed by heat. The dye used in the laser wavelength region, for example, has a refractive index of 1.7 or more in the 780 nm band, a decomposition temperature of about 80 to 300 ° C., no melting point, or a decomposition temperature. The difference is within 100 ° C, the coating property is easily melted in the organic solvent, and is selected as a material having good uniformity after coating.

Pigments satisfying these conditions include anthraquinone, dioxadine, triphenodithiazine, phenanthrene, cyanine, phthalocyanine, Naphthalocyanine, merocyanine, merocyanine, pyrylium, xxnthine, triphenylemethane, croconium, azo, and indigoid Pigments consisting of indigoids, methine, azulene, azulene, squaria, sulfide, and methane dithiolate pigments alone or in a mixture thereof There is this.

In addition to relatively inexpensive aluminum (Al), the reflective layer 30 may be used as Au, Cr, Ti, Cu, Ni, Pt, Ag, Ta, Fe, and alloys thereof, and the thickness thereof is 500 to 500. 2500 kPa is suitable and is formed by vacuum deposition, E-beam or sputtering.

The protective layer 40 is a transparent material having a strong impact strength having a characteristic of protecting the reflective layer 30 and printing the contents of the disc on the surface thereof by printing, UV-curable resin, acrylic resin , Polycarbonate resin, polysiloxane resin and the like are used as main components. The protective layer 40 is formed by dissolving the above-mentioned material in an organic solvent and then spin coating it on the reflective layer 30. At this time, the organic solvent is not particularly limited as long as the material of the protective layer 40 can be easily dissolved without damaging the reflective layer 30. An initiator, a polymerization catalyst, a cross-linking agent, and the like, which adjust the reaction rate and hardness according to the content thereof, are suitably contained in the organic solvent. The coating solution made by dissolving the protective layer 40 material in the organic solvent in such a way that the content of the organic solvent is adjusted to have a viscosity of about 200 to 1000 mPass, or in the case of a photocurable UV-curable resin, an appropriate amount before spin coating. The viscosity is previously adjusted within the above range by pre-curing irradiation with light.

Using the solution thus prepared as a material, a film is formed on the reflective layer 30 by spin coating to a predetermined thickness, and then the protective layer 40 is completed by curing such as thermosetting or photocuring.

On the other hand, if the viscosity of the coating solution is 200mPass or less, the fluidity of the solution is improved to improve the permeability of the hole formed in the reflective layer 30 to damage the recording layer 20, if the viscosity is more than 1000mPass protective layer (40) It is difficult to control the thickness of the film.

Hereinafter, the features of the present invention will be described in detail through examples. However, the present invention is not necessarily limited to the scope of the following examples.

<Example 1>

N on a 1.2 mm thick polycarbonate (PC) substrate 10 having a guide valley having a depth of 153 nm, a top width of 0.8 m, a bottom width of 0.25 m, a medium width of 500 nm and a track pitch of 1.6 m. N'-2,5-cyclohexadiene-1,4-diylidenebis [4- (dibutylamino) -N- [4- (dibutylamino) phenyl] -bis [(OC-6-11) -Hexafluoro-antimonate (10)] (NK-3219 (λ _max = 720 nm), Nippon Kanko Shinko Kenkusho Co., Ltd.) 4.4 g of a dye solution dissolved in 100 ml of diacetone alcohol using a spin coater. After rotating for 5 seconds at 50 rpm for 15 seconds at 1500 rpm for 30 seconds at 4000 rpm for coating and drying, the Au reflective layer 30 was formed to a thickness of 100 nm using a sputter. UV cured resin (Philips 40016) with 80 mPass viscosity (measured by German standard DIN53788 method) was pretreated by UV lamp (Xenon lamp) for 5 seconds with light power of 0.03W / m ² , and the viscosity was increased to 350mPass. After spin-coating at 4,500 rpm with this cured resin on the Au reflective layer 30, UV curing was performed to form a protective layer 40 with a thickness of about 10 µm. The recording characteristics (BLER (block error rate)) evaluated by the evaluation apparatus (CD-CATS; Audio Developement, Sweden) were 15, E- after recording on the disc thus produced by the recording apparatus (Yamaha recorder CD-R). 32 is 0, the jitter value is 21nsec, and the maximum reflectance Rtop is 71%.

<Example 2>

Except that the metal layer in Example 1 was replaced with Al having a thickness of 100 nm, disks were prepared in the same manner to evaluate their performance. The recording characteristics (BLER (block error rate)) evaluated by the evaluation apparatus (CD-CATS; Audio Developement, Sweden) were 52, E- 32 is 0, jitter value is 25nsec, and maximum reflectance (Rtop) is 62%.

<Example 3>

A disk was manufactured in the same manner as in Example 2, except that the resin for the protective layer 40 was replaced by an ultraviolet curable resin (40039 by Philips) having a viscosity of about 50 mPass (measured by the German standard DIN53788 method). The ultraviolet curable resin was pre-cured with an optical power of about 0.03 W / m ² by a UV lamp (xenon lamp) to increase its viscosity to 280 mPass, and then 4500 rpm with the cured resin on the Al reflective layer 30. After spin coating at, UV-lamp cured to form a protective layer 40 of about 8㎛ thickness. The recording characteristics (BLER (block error rate)) evaluated by the evaluation apparatus (CD-CATS; Audio Developement, Sweden) was 47, E- after recording on the disc thus produced by the recording apparatus (Yamaha recorder CD-R). 32 is 0, jitter is 24 nsec, and the maximum reflectance (Rtop) is 62%.

<Example 4>

A disk was prepared in the same manner as in Example 2, except that the resin for the protective layer 40 was replaced by an ultraviolet curable resin (40025, manufactured by Philips) having a viscosity of about 120 mPass (measured by the German standard DIN53788 method). The ultraviolet curable resin was pre-cured with an optical power of about 0.03 W / m ² by a UV lamp (xenon lamp) to increase its viscosity to 500 mPass, and then onto the Al reflective layer 30 as 4500 rpm with the cured resin. After spin coating at, UV-lamp cured to form a protective layer 40 of about 12㎛ thickness. The recording characteristics (BLER (block error rate)) evaluated by the evaluation apparatus (CD-CATS; Audio Developement, Sweden) were 72, E- after recording on the disc thus produced by the recording apparatus (Yamaha recorder CD-R). 32 is 0, the jitter value is 27nsec, and the maximum reflectance (Rtop) is 62%.

<Comparative Examples 1 to 3>

In Example 2, when the protective layer is formed, a curing agent having low viscosity without pre-curing was coated on the aluminum reflective layer 30 and cured. Immediately after manufacture, the CD-R recorder recorded and evaluated the recording characteristics (BLER (block error rate) was not so great as 76, but after one day, the disc was damaged so that it could not be evaluated. The results obtained by spin coating and curing 40016 (applied in Comparative Example 1), 40039 (applied in Comparative Example 2) and 40025 (applied in Comparative Example 3) on the aluminum reflective layer 30 were evaluated in the same manner as above. After this, all of them were badly damaged and the evaluation was difficult.

As described above, according to the method of manufacturing a write-once type optical recording medium according to the present invention, the recording layer 20 in the film formation process by the protective layer resin having an appropriate viscosity thereon even for a low-cost aluminum as a reflective layer material Since the permeability to the path is suppressed, damage to the recording layer can be reduced, thereby improving the recording characteristics and reducing the manufacturing cost.

Claims (16)

A method of manufacturing a write-once-type optical recording medium in which a guide bone is formed, and a recording layer, a reflective layer, and a protective layer are sequentially stacked on the substrate, and can be recorded only once. And the protective layer is formed of an organic material having a viscosity of about 200 to 1000 mPass by curing to a predetermined thickness by spin coating on the reflective layer. The method of manufacturing a recordable optical recording medium according to claim 1, wherein the reflective layer is formed of aluminum. The method of manufacturing a write-once-type optical recording medium according to claim 1, wherein the organic material is an ultraviolet curable resin. The method of manufacturing a write-once optical recording medium according to claim 1, wherein the organic material is one selected from among a multitude of selected resins including acrylic resins, polycarbonate resins, and polysiloxane resins. The method of manufacturing a write-once optical recording medium according to claim 3, wherein the ultraviolet curable resin viscosity is adjusted by pretreatment by a predetermined amount of light irradiation. The method of manufacturing a write-once-type optical recording medium according to claim 5, wherein the viscosity is adjusted by pretreatment for several seconds to several tens of seconds with an optical power of about 0.03 W / m ² by the UV curing resin UV lamp. The method of manufacturing a recordable optical recording medium according to claim 1, wherein the guide bone has a depth of about 50 to 300 nm and a median width of about 200 to 550 nm. The method of manufacturing a write-once optical recording medium according to claim 1, wherein the substrate is formed of any one material selected from the group consisting of polycarbonate, PMAA, epoxy resin, polyester, and amorphous polyolefin as a transparent material. The method of manufacturing a write-once-type optical recording medium according to claim 8, wherein the heat distortion temperature of the substrate material is 80 to 200 ° C. The method of manufacturing a write-once-type optical recording medium according to claim 1, wherein the recording layer is made of an organic material which is easily deformed or decomposed by heat. 11. The method of manufacturing a recordable optical recording medium according to claim 10, wherein the organic material of the recording layer has a thermal decomposition temperature of 80 to 300 deg. The method of manufacturing a write-once-type optical recording medium according to claim 10, wherein the difference between the thermal decomposition temperature and the melting temperature of the organic material in the recording layer is 100 ° C or less. The method of manufacturing a recordable optical recording medium according to claim 10, wherein the organic material of the recording layer has a refractive index of 1.7 or more. The organic material of the recording layer according to claim 10, wherein the organic material of the recording layer is anthraquinone, deoxydine, triphenodithiazine, phenanthrene, cyanine, phthalocyanine, naphthalocyanine, merocyanine, pyryllium, or xan. At least one pigment selected from the group consisting of tin, triphenylmethane, croconium, azo, indigoide, methine, azulene, squaria-based, sulfide-based, methane dithiolate-based pigments and mixtures thereof Method of manufacturing a recordable optical recording medium comprising a. The method of manufacturing a recordable optical recording medium according to claim 1, wherein the reflective layer has a thickness of 500 to 2500 kPa. The write-once optical recording medium of claim 1, wherein the reflective layer is formed of one metal selected from the group consisting of Au, Cr, Ti, Cu, Ni, Pt, Ag, Ta, Fe, and alloys thereof. Manufacturing method.