JP2008090925A - Optical recording medium and method for manufacturing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical recording medium and a method for manufacturing the optical recording medium which has good recording characteristic and high productivity by using ultraviolet curable resin which become hardened for a short time period by a low irradiation level of ultraviolet to regulate increase transmitivity of an organic pigment layer. <P>SOLUTION: The ultraviolet curable resin in which a proportion of three functional acrylic monomer is 5 to 20 wt.% to a total weight of a two functional acrylic monomer and the three functional acrylic monomer becomes hardened by a low ultraviolet irradiation level, that is, accumulated light intensity of the ultraviolet of 100 to 150 mj/cm<SP>2</SP>since the use of the ultraviolet curable resin enables regulation of increase of transmission of the organic pigment layer which has contact with the ultraviolet curable resin. Further, the method for manufacturing the optical recording medium by using the ultraviolet curable resin can produce the optical recording medium which has the good recording characteristic in good productivity. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a write-once type optical recording medium having an information recording layer having an organic dye layer for recording or reproducing an information signal using a laser beam, and a method for manufacturing the optical recording medium.

  As a digital information signal recording medium, an optical recording medium in which information signals are recorded / reproduced by irradiating laser light from the outside in terms of recording capacity, random accessibility, portability, price, etc. is industrial. Widely used from consumer use to consumer use. These optical recording media include read-only types such as CD (Compact Disc) and DVD (Digital Versatile Disc), recordable types such as CD-R and DVD-R, CD-RW and DVD. Various types such as a rewritable type capable of recording any number of times such as RW, DVD-ROM, DVD-RAM, and BD (Blu-ray Disc) have been developed as a large-capacity optical recording medium.

  Among these optical recording media, write-once type optical recording media in which organic dyes are used for recording information signals have no risk of erroneous erasure because information signals recorded once cannot be rewritten or erased. It is often used as a recording medium for image data, video data, etc. that do not need to be saved or rewritten. In addition to being relatively inexpensive, write-once type optical recording media are compatible with read-only optical recording media, so that they can also be used for carrying and distributing data.

  In these optical recording media, with the rapid development of information communication and image processing technology in recent years, further improvement in recording capacity is required, and this is no exception in write-once type optical recording media. As a technique for improving the recording capacity of the optical recording medium, in addition to the technique of increasing the recording density in the information recording layer by miniaturizing the track pitch and pits such as grooves and lands of the information recording layer for recording information signals, A technique of forming a plurality of information recording layers is mainly used.

  As a method of forming a plurality of information recording layers on an optical recording medium, a method of attaching a plurality of substrates each having an information recording layer or a method of forming an information recording layer on an intermediate layer of an optical recording medium is generally used. It is done. For the bonding of the substrates and the formation of the intermediate layer, an ultraviolet curable resin that is easy to handle and inexpensive, cures in a short time, has good productivity, and has good heat resistance after curing is often used.

  However, in the case of a write-once type optical recording medium having an organic dye layer in the information recording layer, if the highly active uncured UV curable resin is in contact with the organic dye layer for a long time, the organic dye in the organic dye layer As a result, the transmittance of the organic dye layer is increased. If the transmittance of the organic dye layer is large, the organic dye layer cannot sufficiently absorb the recording laser light irradiated during recording of the information signal and cannot generate heat, and the dye decomposition of the organic dye becomes insufficient, and the information signal is recorded. It is difficult to perform well.

  For example, in the following [Patent Document 1], for example, a protective layer is formed on an information recording layer using an organic dye, and two sheets of UV curable resin and an organic dye layer are not brought into direct contact with each other. There is a description regarding a method of manufacturing an optical recording medium having two information recording layers on which a substrate is bonded.

JP 2000-339766 A

  However, as described in [Patent Document 1], in the method of forming a protective layer between the organic dye layer and the ultraviolet curable resin layer, if the protective layer to be formed is thick, the loss of incident laser light is large. In addition to the possibility that the recording / reproducing characteristics of the optical recording medium may be hindered, there are problems that the number of steps for forming the protective layer is increased and productivity is lowered, and further improvement is desired.

  The present invention has been made in view of the above circumstances, and provides an optical recording medium that suppresses an increase in transmittance of an organic dye layer and has good recording characteristics and high productivity, and a method for manufacturing the optical recording medium. For the purpose.

The present invention
An optical recording medium,
A substrate,
An organic dye layer formed on the substrate for recording information signals;
UV curable resin layers 10 and 10a formed on the organic dye layer in contact with the organic dye layer;
Have
By providing the optical recording media 50 and 60, the ultraviolet curable resin layers 10 and 10a are layers obtained by curing an ultraviolet curable resin containing a bifunctional acrylic monomer and a trifunctional acrylic monomer. Solve the problem.

  Further, the ratio of the trifunctional acrylic monomer in the ultraviolet curable resin before curing is in the range of 5% by weight to 20% by weight with respect to the total weight of the bifunctional acrylic monomer and the trifunctional acrylic monomer. By providing the above-described optical recording media 50 and 60, the above problems can be solved.

Furthermore, a method for manufacturing an optical recording medium, comprising:
An organic dye layer forming step of forming an organic dye layer on the substrate;
After the organic dye layer forming step, an ultraviolet curable resin containing a bifunctional acrylic monomer and a trifunctional acrylic monomer is applied to the surface of the organic dye layer, and the applied ultraviolet curable resin is irradiated with ultraviolet rays to form the ultraviolet curable resin. UV curing resin curing process to cure the resin,
Have
In the ultraviolet curable resin curing step, the ratio of the trifunctional acrylic monomer in the ultraviolet curable resin before curing is 5% by weight to 20% by weight with respect to the total weight of the bifunctional acrylic monomer and the trifunctional acrylic monomer. By providing a method for producing optical recording media 50 and 60, wherein the integrated light quantity of ultraviolet rays applied to the ultraviolet curable resin is in the range of 100 mj / cm ^{2 to} 150 mj / cm ² . Solve the above problems.

According to the optical recording medium and the manufacturing method thereof according to the present invention,
By optimizing the ultraviolet curable resin, the ultraviolet curable resin can be cured in a short time with a small amount of ultraviolet irradiation. For this reason, since the contact time between the uncured ultraviolet curable resin and the organic dye layer is shortened, an increase in the transmittance of the organic dye layer can be suppressed. Therefore, an optical recording medium having good recording characteristics can be manufactured with high productivity.

  An embodiment of an optical recording medium and a method for manufacturing the same according to the present invention will be described with reference to the drawings. FIG. 1 is a schematic sectional view of an optical recording medium according to the first embodiment of the present invention. FIG. 2 is a schematic sectional view of an optical recording medium according to the second embodiment of the present invention. FIG. 3 is a diagram for explaining the outline of the manufacturing method of the optical recording medium of the first embodiment according to the present invention. FIG. 4 is a diagram for explaining the outline of the manufacturing method of the optical recording medium of the second embodiment according to the present invention. FIG. 5 is a diagram showing the relationship between the integrated light quantity and the elastic modulus when the blending ratio of the monofunctional acrylic monomer and the bifunctional acrylic monomer of the ultraviolet curable resin is changed. FIG. 6 is a graph showing the relationship between the integrated light amount and the transmittance of the organic dye layer when the blending ratio of the monofunctional acrylic monomer and the bifunctional acrylic monomer of the ultraviolet curable resin is changed. FIG. 7 is a diagram showing the relationship between the integrated light amount and the elastic modulus when the blending ratio of the bifunctional acrylic monomer and the trifunctional acrylic monomer of the ultraviolet curable resin according to the present invention is changed. FIG. 8 is a diagram showing the relationship between the integrated light amount and the transmittance of the organic dye layer when the blending ratio of the bifunctional acrylic monomer and the trifunctional acrylic monomer of the ultraviolet curable resin according to the present invention is changed.

  On each surface of the first substrate 1 and the second substrate 5 constituting the optical recording medium 50 shown in FIG. 1, an uneven pattern composed of lands and grooves is formed concentrically or spirally. Incidentally, in areas other than the recording areas of the first substrate 1 and the second substrate 5, pre-pits (not shown) in which information signals relating to the optical recording medium itself are recorded are formed. On the concavo-convex pattern of the first substrate 1, the first information recording layer 4 is formed by forming the reflective layer 2 and the first organic dye layer 3. Further, the second information recording layer 8 is formed on the uneven pattern of the second substrate 5 by forming the second organic dye layer 6 and the transflective layer 7. The first substrate 1 having the first information recording layer 4 and the second substrate 5 having the second information recording layer 8 are arranged such that the first information recording layer 4 and the second information recording layer 8 face each other. It joins via the ultraviolet curable resin layer 10. At this time, the ultraviolet curable resin described later is used for the ultraviolet curable resin layer 10.

  Also, the optical recording medium 60 shown in FIG. 2 has a concave / convex pattern formed on one surface of the first substrate 1 in the same manner as the optical recording medium 50, and the reflective layer 2 and the first layer are formed on the concave / convex pattern of the first substrate 1. The first information recording layer 4 is formed by forming one organic dye layer 3. On the first information recording layer 4 of the first substrate 1, an ultraviolet curable resin, which will be described later, is applied, and an uneven pattern is formed on the applied ultraviolet curable resin by a photopolymer method using a stamper having an uneven pattern. At the same time, it is cured by ultraviolet irradiation to form an ultraviolet curable resin layer 10a having a concavo-convex pattern of a predetermined dimension. On the concave-convex pattern of the ultraviolet curable resin layer 10a, the second information recording layer 8 is formed by sequentially forming the transflective layer 7 and the second organic dye layer 6. On the second information recording layer 8, a light transmission layer 12 is formed which becomes a laser light incident surface and protects the second information recording layer 8.

  As materials of the first substrate 1 and the second substrate 5, various thermoplastic resins such as polycarbonate, polymethyl methacrylate, polystyrene, polycarbonate / polystyrene copolymer, polyvinyl chloride, alicyclic polyolefin, polymethylpentene, and thermosetting resins are used. Or a ceramic material such as soda lime glass, soda aluminosilicate glass, borosilicate glass, or quartz glass can be used. Among these, polycarbonate is easy to mold.

  The thicknesses of the first substrate 1 and the second substrate 5 vary depending on the optical recording medium to be manufactured, but are approximately 0.6 mm when compatible with DVD. Also, when using a blue laser beam having a wavelength λ of 405 nm and an objective lens having a numerical aperture NA of 0.85 and having compatibility with a high-density optical recording medium having a guide groove with a track pitch of 0.32 μm The thickness of the first substrate 1 is about 1.1 mm, and the thickness of the second substrate 5 or the light transmission layer 12 is about 0.1 mm.

  The reflection layer 2 reflects the reproduction laser beam irradiated when reproducing the information signal recorded on the first information recording layer 4 to the reproduction apparatus side, and the recording laser beam irradiated when recording the information signal It has a function of effectively radiating heat generated by being absorbed by the first organic dye layer 3. The material of the reflective layer 2 is made of metal such as Al, Au, Ag, Cu, Ti, Cr, Ni, Ta, Mo, Fe, Zn, Ga, As, and Pd, or two or more kinds of metals including the metal. Or a mixture of the metal or the alloy and a metal compound such as a metal oxide, metal nitride, metal carbide, metal sulfide, or metal fluoride. Among them, Al, Au, Ag, or an alloy thereof is a material that has both high reflectivity and high thermal conductivity.

The semi-transmissive reflection layer 7 reflects the reproduction laser beam irradiated when reproducing the information signal recorded on the second information recording layer 8 to the reproduction apparatus side and is irradiated when recording the information signal. It has a function of effectively radiating heat generated by absorption of light by the second organic dye layer 6. In addition to these functions, the first information recording layer 4 also has a function of transmitting laser light irradiated. As a material of the transflective layer 7, a dielectric material such as SiO ₂ (silicon oxide) can be used in addition to the material used for the reflective layer 2 described above.

  The first organic dye layer 3 and the second organic dye layer 6 absorb the high-power recording laser light irradiated when recording the information signal and generate heat, and the portion irradiated with the laser light undergoes dye decomposition. This causes the refractive index to change. Thereby, recording pits having different refractive indices are formed in the first organic dye layer 3 and the second organic dye layer 6 depending on the information signal to be recorded. When the recorded information signal is reproduced, the information signal is reproduced by detecting that the intensity of the reflected light is different depending on the presence or absence of the recording pit by irradiating a low-power reproduction laser beam. The formation of the recording pits in the first organic dye layer 3 and the second organic dye layer 6 is irreversible and once recorded in the first organic dye layer 3 and the second organic dye layer 6. Information signals cannot be erased or rewritten.

  The first organic dye layer 3 and the second organic dye layer 6 are organic dyes having a basic skeleton such as cyanine-based, phthalocyanine-based, and azo-based components, and the differential thermal characteristics and wavelength characteristics are optimized by adjusting the components. The viscosity is adjusted so that it can be applied. When applying the first organic dye layer 3 and the second organic dye layer 6 by spin coating, the temperature management of the organic dye and the temperature and humidity management of the application environment are performed with sufficient accuracy so that the thickness unevenness is reduced. In particular, it is preferable to control the temperature within ± 0.1 ° C. Moreover, the film thickness of the 1st organic pigment | dye layer 3 and the 2nd organic pigment | dye layer 6 is set suitably so that it may become a suitable light absorbency.

  The light transmission layer 12 has a function of transmitting the laser light irradiated to the first information recording layer 4 and the second information recording layer 8 and protecting the second information recording layer 8. The light transmission layer 12 may be formed by adhering a substrate or a film made of a material that can be used for the first substrate 1 and the second substrate 5 to the second information recording layer 8, or an ultraviolet curable resin. Such a synthetic resin may be applied to the second information recording layer 8 to a predetermined thickness and then cured. In addition, when forming the light transmissive layer 12 using an ultraviolet curable resin, it is preferable to use the ultraviolet curable resin mentioned later.

The ultraviolet curable resin layers 10 and 10a contain a bifunctional acrylic monomer and a trifunctional acrylic monomer, which will be described later, and cure the ultraviolet curable resin that reaches the curing end point when the integrated light amount of ultraviolet rays is 100 mj / cm ^{2 to} 150 mj / cm ^2. Formed. For this reason, the contact time between the uncured ultraviolet curable resin and the organic dye layer is short, and the transmittance of the adjacent first organic dye layer 3 does not increase greatly.

  In FIGS. 1 and 2, an information recording layer having an organic dye layer is used as an example of an optical recording medium having two layers. However, the information recording layer is not particularly limited to two layers, and the information recording layer is a single layer. Or you may have three or more layers. 1 and 2, the example in which the land of the first information recording layer 4 and the groove of the second information recording layer 8 face each other is used. However, the groove of the first information recording layer 4 and the second An uneven pattern may be formed so that the grooves of the information recording layer 8 face each other.

  Here, the manufacturing method of the optical recording medium 50 according to the present invention will be described in more detail. FIG. 3 is a diagram for explaining the outline of the manufacturing method of the optical recording medium 50 according to the first embodiment of the present invention.

  First, in the substrate manufacturing process, as shown in FIG. 3A, the first substrate 1 and the second substrate 5 in which lands and grooves are formed as concavity and convexities in a concentric or spiral shape on one side are made of synthetic resin. When the material is used, it is mainly produced by injection molding, and when the material is ceramic, it is produced mainly by the photopolymer method.

  Next, in the information recording layer forming step including the organic dye layer forming step, as shown in FIG. 3B, the reflection layer 2 is formed on the uneven pattern of the first substrate 1 by a known method such as sputtering or vapor deposition. The film is formed by a film method. Next, as shown in FIG. 3C, an organic dye is applied on the reflective layer 2 of the first substrate 1 by a known method such as a spin coating method to form the first organic dye layer 3. Thereby, the first information recording layer 4 is formed on the first substrate 1.

  Apart from this, as shown in FIG. 3D, the second organic dye layer 6 is formed by applying the organic dye in the same manner on the concave-convex pattern of the second substrate 5. Next, as shown in FIG. 3 (e), a transflective layer 7 is formed on the second organic dye layer 6 of the second substrate 5. Similarly to the method for forming the reflective layer 2, a known film forming method such as a sputtering method or a vapor deposition method can be used as the method for forming the transflective layer 7. Thereby, the second information recording layer 8 is formed on the second substrate 5.

  Next, in the ultraviolet curable resin curing step, an ultraviolet curable resin, which will be described later, is applied onto the first information recording layer 4 of the first substrate 1 or the second information recording layer 8 of the second substrate 5 by using a spin coating method or the like. Apply to a predetermined thickness. After that, as shown in FIG. 3 (f), the first substrate 1 and the second substrate 5 are coated with an ultraviolet curable resin applied so that the first information recording layer 4 and the second information recording layer 8 face each other. Then, the ultraviolet curable resin is irradiated and cured by bonding with ultraviolet rays. At this time, the cured ultraviolet curable resin becomes the ultraviolet curable resin layer 10. Thereby, an optical recording medium 50 having two information recording layers is manufactured.

  In addition, in order to join the first substrate 1 and the second substrate 5, an ultraviolet curable resin that reaches the curing end point by short-time ultraviolet irradiation described later is used, so that the uncured ultraviolet curable resin and the first organic dye layer 3 are bonded. The time required for contact with the organic dye is short, and almost no chemical change occurs in the organic dye of the first organic dye layer 3. For this reason, it can suppress that the transmittance | permeability of the 1st organic pigment | dye layer 3 increases.

  Next, the manufacturing method of the optical recording medium 60 according to the present invention will be described in more detail. FIG. 4 is a diagram for explaining the outline of the manufacturing method of the optical recording medium 60 according to the second embodiment of the present invention.

  First, in the substrate manufacturing process, as in FIG. 3A, the first substrate 1 having lands and grooves concentrically or spirally formed on one side as a concavo-convex pattern is manufactured.

  Next, in the first information recording layer forming step including the organic dye layer forming step, the reflective layer 2 is formed on the concavo-convex pattern of the first substrate 1 in the same manner as in FIG. Next, as in FIG. 3C, the first organic dye layer 3 is formed on the reflective layer 2 of the first substrate 1. Thereby, as shown in FIG. 4A, the first information recording layer 4 is formed on the concavo-convex pattern of the first substrate 1.

  Next, in the ultraviolet curing resin curing step, the ultraviolet curing resin layer 10a having a concavo-convex pattern having a predetermined dimension is formed by the following procedure by using a photopolymer method. First, as shown in FIG. 4B, an ultraviolet curable resin (shown by hatching in FIG. 4B) to be described later is formed on the first information recording layer 4 of the first substrate 1 by spin coating or the like. Apply at a predetermined thickness.

  Thereafter, as shown in FIG. 4 (c), a resin or metal stamper 20 in which a matrix having a concavo-convex pattern with a predetermined dimension is formed on one side is adhered to the applied ultraviolet curable resin, and then ultraviolet rays are applied. To cure the ultraviolet curable resin and form the ultraviolet curable resin layer 10a. At this time, the ultraviolet curable resin layer 10a may be formed by irradiating ultraviolet rays after the stamper 20 is peeled off. However, when the concavo-convex pattern of the ultraviolet curable resin layer 10a is required to have high dimensional accuracy, the stamper 20 is removed. It is preferable that the ultraviolet curable resin layer 10a is formed by peeling off the stamper 20 after irradiating ultraviolet rays while being adhered to cure the ultraviolet curable resin.

  By these procedures, as shown in FIG. 4D, an ultraviolet curable resin layer 10a having a concavo-convex pattern having a predetermined dimension is formed on the first information recording layer 4. In addition, since the ultraviolet curable resin used at this time is also an ultraviolet curable resin that reaches the curing end point by short-time ultraviolet irradiation described later, as in the method of manufacturing the optical recording medium 50, the uncured ultraviolet curable resin and the first organic resin are used. The time for which the organic dye of the dye layer 3 is in contact is short, and there is almost no chemical change in the organic dye of the first organic dye layer 3. For this reason, the increase in the transmittance of the first organic dye layer 3 can be suppressed.

  Next, in the second information recording layer forming step including the organic dye layer forming step, the transflective layer 7 is formed on the concave / convex pattern of the ultraviolet curable resin layer 10a. For the film formation of the transflective layer 7, a known film formation method such as a sputtering method can be used as in FIG. Next, the second organic dye layer 6 is formed by applying an organic dye on the transflective layer 7 by a known method such as a spin coat method. Thereby, as shown in FIG. 4E, the second information recording layer 8 is formed on the ultraviolet curable resin layer 10a.

  Finally, in the light transmission layer forming step, the light transmission layer 12 is formed on the second information recording layer 8 as shown in FIG. Thereby, an optical recording medium 60 having two information recording layers is manufactured. As a method for forming the light transmission layer 12, a substrate such as polycarbonate or a film is adhered with an adhesive or the like, and a resin such as an ultraviolet curable resin is applied to a predetermined thickness by a spin coat method or the like, and then irradiated with ultraviolet rays. There is a method of forming the resin by curing the resin. In particular, when the light transmission layer 12 is formed of an ultraviolet curable resin, the transmittance of the second organic dye layer 6 can be increased by using the same ultraviolet curable resin as that used for forming the ultraviolet curable resin layer 10a. The increase can be kept low.

  In the case of manufacturing an optical recording medium having three or more information recording layers, it can be manufactured by repeating the ultraviolet curable resin curing step and the information recording layer forming step among the above manufacturing steps. In the case of producing an optical recording medium having a single information recording layer, the concave-convex pattern is not formed on the ultraviolet curable resin layer 10a in the ultraviolet curable resin curing step, and the second information recording layer forming step, and It can be produced by not performing the light transmission layer forming step. In this case, the ultraviolet curable resin layer 10 a becomes the light transmission layer 12. Alternatively, the light transmitting layer forming step can be performed after the first information recording layer forming step without performing the ultraviolet curable resin curing step and the second information recording layer forming step.

  Next, the ultraviolet curable resin used for the optical recording medium according to the present invention will be described in detail.

  The inventor paid attention to the number of functional groups of the acrylic monomer as a means for curing the ultraviolet curable resin in a short time. Therefore, first, the number of functional groups of the acrylic monomer that is the main component of the ultraviolet curable resin according to the present invention was selected. The acrylic monomer that is the main component of the UV curable resin is generally a monofunctional or bifunctional acrylic monomer. Here, the UV curable resin is changed by changing the mixing ratio of the monofunctional acrylic monomer and the bifunctional acrylic monomer. Make it. Then, each of the produced ultraviolet curable resins is irradiated with ultraviolet rays while changing an ultraviolet ray integrated irradiation amount (hereinafter referred to as an integrated light amount) which is an ultraviolet ray amount to be irradiated. The transmittance of the organic dye layer is evaluated. From the evaluation results, the number of functional groups of the acrylic monomer that is the main component of the ultraviolet curable resin used in the optical recording medium according to the present invention is selected.

  First, the blending ratio of bisphenol AEO adduct diacrylate (manufactured by Kyoeisha Chemical Co., Ltd.) as a bifunctional acrylic monomer is changed to 100 wt%, 80 wt%, 60 wt%, 50 wt%, 40 wt%, 30 wt%, 20 wt%. The remainder was blended with phenoxydiethylene glycol acrylate (manufactured by Kyoeisha Chemical Co., Ltd.) as a monofunctional acrylic monomer so as to be 100%. 4 wt% of hydroxysilphenyl ketone as a photoinitiator was added to the total weight of the mixture of the monofunctional acrylic monomer and the bifunctional acrylic monomer to prepare an ultraviolet curable resin.

Next, the produced ultraviolet curable resin was applied onto a polycarbonate resin substrate having a thickness of 0.6 mm using a spin coater so as to have a layer thickness of about 50 μm at a rotation speed of about 700 rpm. Next, the ultraviolet curable resin applied to a polycarbonate resin substrate, an integrated light quantity of ^{100mj / cm 2, 200mj / cm} 2, 400mj / cm 2, 600mj / cm 2, 800mj / cm 2, 1000mj / cm 2, 1500mj / Cm ² and 2000 mj / cm ^2, and ultraviolet rays were irradiated. The integrated light amount was changed by changing the irradiation time while keeping the amount of ultraviolet light to be irradiated constant.

  Next, the ultraviolet curable resin irradiated with ultraviolet rays was peeled from the polycarbonate resin substrate, and then cut into a size of 1 cm × 4 cm to obtain a test piece. Both ends of the obtained test piece were sandwiched between the sample mounting portions of the tensile tester so that the length of the test piece was 2.5 cm, and the tensile strength when the test piece was broken in an atmosphere at 40 ° C. was measured. The elastic modulus of the ultraviolet curable resin was calculated from the tensile strength of the obtained test piece and the dimensions of the test piece. FIG. 5 shows the relationship between the integrated light quantity and the elastic modulus of the ultraviolet curable resin at each blending ratio.

Separately, phthalocyanine-based organic dye red 2 (manufactured by Toyo Ink Co., Ltd.) dissolved in ethanol at 1 wt% is formed on a polycarbonate resin substrate having a thickness of 1.1 mm using a spin coater so that the film thickness is about 80 nm. The organic dye layer was formed by coating under the condition of about 2000 rpm. Next, a test substrate is obtained by applying an ultraviolet curable resin prepared at the above-mentioned blending ratio on the applied organic dye layer using a spin coater at a rotation speed of about 700 rpm so that the layer thickness is about 50 μm. It was. Next, in the same manner as in the measurement of elastic modulus on the obtained test substrate, the integrated light quantity ^{100mj / cm 2, 200mj / cm} 2, 400mj / cm 2, 600mj / cm 2, 800mj / cm 2, 1000mj / cm 2 The ultraviolet curable resin on the test substrate was irradiated with ultraviolet rays while being changed to 1500 mj / cm ² and 2000 mj / cm ² .

  Then, the transmittance | permeability in the laser beam of wavelength 515nm of the organic pigment | dye layer of each test board | substrate irradiated with the ultraviolet-ray was measured using the spectrophotometer. FIG. 6 shows the relationship between the integrated light quantity of the ultraviolet curable resin and the transmittance of the organic dye layer at each compounding ratio. In addition, since the organic dye layer using the phthalocyanine-based organic dye red 2 has an extremely low transmittance around the wavelength of 515 nm, an increase in the transmittance of the organic dye layer due to the influence of the ultraviolet curable resin appears remarkably.

From FIG. 5, the amount of integrated light reaching the point at which the elastic modulus of the ultraviolet curable resin is saturated, that is, the curing end point at which the ultraviolet curable resin is completely cured is 40 wt% of the blending ratio of the bifunctional acrylic monomer (marked with ▲ in FIG. 5) Is 1000 mj / cm ² , whereas the blending ratio of bifunctional acrylic monomer is 80 wt% (marked in FIG. 5) is 600 mj / cm ² , and the blending ratio of bifunctional acrylic monomer is 100 wt% (marked in FIG. 5). ) And 200 mj / cm ² , as the blending ratio of the bifunctional acrylic monomer increases and the blending ratio of the monofunctional acrylic monomer decreases, the integrated light amount reaching the curing end point decreases. From this, it can be seen that the ultraviolet curable resin having a large blending ratio of the bifunctional acrylic monomer is completely cured even after a short period of ultraviolet irradiation.

From FIG. 6, the integrated light quantity at which the transmittance of the organic dye layer formed on the test substrate is constant is 1000 mj / cm ^{2 when} the blending ratio of the bifunctional acrylic monomer is 40 wt% (▲ in FIG. 6). against, 2 mixing ratio of functional acrylic monomer is 80 wt% and (in FIG. 6 □ mark) at 600 mJ / ^cm 2, the compounding ratio of 2-functional acrylic monomer is 100 wt% (in FIG. 6 ○ mark) at 200 mj / cm ^2, FIG. It can be seen that the blending ratio of the bifunctional acrylic monomer increases and the blending ratio of the monofunctional acrylic monomer decreases as the curing end point of No. 5 decreases.

  In addition, the transmittance after the curing end point of the organic dye layer formed on the test substrate is about 70% when the blending ratio of the bifunctional acrylic monomer is 40 wt% (marked with ▲ in FIG. 6). When the compounding ratio of the monomer is 80 wt% (marked in FIG. 6), it is about 43%, and when the compounding ratio of the bifunctional acrylic monomer is 100 wt% (marked with a circle in FIG. 6), it is about 12%. It can be seen that it increases and decreases as the blending ratio of monofunctional acrylic monomer decreases. This is because the UV curable resin that requires a large amount of accumulated light for curing, the uncured active UV curable resin reacts with the organic dye until the UV curable resin reaches the end of curing, and the transmittance of the organic dye layer It is inferred to increase In contrast, an ultraviolet curable resin that cures with a small amount of accumulated light hardly reacts with organic dyes because most of the ultraviolet curable resin is cured and inactivated at an early stage when ultraviolet irradiation is started. As a result, it is presumed that the increase in the transmittance of the organic dye layer can be suppressed.

  From the results of FIGS. 5 and 6, the bifunctional acrylic monomer and the monofunctional acrylic monomer tend to be cured with a small amount of accumulated light in the ultraviolet curable resin using the bifunctional acrylic monomer. A bifunctional acrylic monomer is used as the main component of the cured resin. The bifunctional acrylic monomer preferably contains bisphenol A or bisphenol F as a raw material and bisphenol A or bisphenol F in the molecular structure.

  Next, the relationship between the blending ratio between the bifunctional acrylic monomer and the trifunctional acrylic monomer of the ultraviolet curable resin used in the optical recording medium according to the present invention, its elastic modulus, and the transmittance of the organic dye layer was examined.

  First, trimethylolpropane trimethacrylate (manufactured by Kyoeisha Chemical Co., Ltd.) as a trifunctional acrylic monomer was changed to 0 wt%, 5 wt%, 10 wt%, 20 wt%, 30 wt%, 40 wt%, 50 wt%, and the rest as the main ingredient It was mix | blended so that it might become 100% with the bisphenol AEO adduct diacrylate as a bifunctional acrylic monomer which is. 4 wt% of hydroxysilphenyl ketone as a photoinitiator was added to the total weight of the mixture of the trifunctional acrylic monomer and the bifunctional acrylic monomer to prepare an ultraviolet curable resin.

Next, the produced ultraviolet curable resin was applied onto a polycarbonate resin substrate having a thickness of 0.6 mm using a spin coater so as to have a layer thickness of about 50 μm at a rotation speed of about 700 rpm. Next, the ultraviolet curable resin applied to a polycarbonate resin substrate, 100 mj ^/ cm ² of integrated quantity of light in the same manner as in FIG. ^{5, 120mj / cm 2, 150mj} / cm 2, 200mj / cm 2, 250mj / cm 2, ^{300mj / cm 2, 350mj / cm} 2, 400mj / cm 2, 450mj / cm 2, 500mj / cm 2 and varied was irradiated with ultraviolet light.

  Next, the ultraviolet curable resin irradiated with ultraviolet rays was peeled from the polycarbonate resin substrate, and then cut into a size of 1 cm × 4 cm to obtain a test piece. Both ends of the obtained test piece were sandwiched between the sample mounting portions of the tensile tester so that the length of the test piece was 2.5 cm, and the tensile strength when the test piece was broken in an atmosphere at 40 ° C. was measured. The elastic modulus of the ultraviolet curable resin was calculated from the tensile strength of the obtained test piece and the dimensions of the test piece. In FIG. 7, the relationship between the integrated light quantity and elastic modulus of the ultraviolet curable resin in each compounding ratio is shown.

Separately, phthalocyanine-based organic dye red 2 dissolved in 1 wt% in ethanol is placed on a polycarbonate resin substrate having a thickness of 1.1 mm using a spin coater at a rotational speed of about 2000 rpm. Was applied to form an organic dye layer. Next, on the coated organic dye layer, a trifunctional acrylic monomer having a blending ratio of 0 wt% to 30 wt% among the UV curable resin produced at the blending ratio is set to a layer thickness of about 50 μm using a spin coater. The test substrate was obtained by coating under conditions of about 700 rpm. Next, in the same manner as in the measurement of elastic modulus on the obtained test substrate, 100 mj ^/ cm ² to integrated quantity of light in the ultraviolet curing resin on the test ^{substrate, 120mj / cm 2, 150mj /} cm 2, 200mj / cm 2, 250mj / Cm ² , 300 mj / cm ² , 350 mj / cm ² , and 400 mj / cm ² . Then, the transmittance | permeability of the laser beam in wavelength 515nm of the organic pigment | dye layer of each test board | substrate irradiated with the ultraviolet-ray was measured using the spectrophotometer. FIG. 8 shows the relationship between the integrated light quantity of the ultraviolet curable resin and the transmittance of the organic dye layer at each compounding ratio.

From FIG. 7, the integrated light amount reaching the curing end point of the UV curable resin is 200 mj / cm ^{2 when} the blending ratio of the trifunctional acrylic monomer is 0 wt% (indicated by ◆ in FIG. 7), whereas that of the trifunctional acrylic monomer is It can be seen that when the blending ratio is 5 wt% to 50 wt%, it becomes smaller as the blending ratio of the trifunctional acrylic monomer is increased to 100 mj / cm ^{2 to} 150 mj / cm ² . From this, it can be seen that the ultraviolet curable resin having a higher blending ratio of the trifunctional acrylic monomer is cured with a smaller amount of integrated light.

  However, the elastic modulus of the cured UV curable resin is about 1900 MPa when the blending ratio of the trifunctional acrylic monomer is 0 wt% (indicated by a ♦ in FIG. 7), whereas the blending ratio of the trifunctional acrylic monomer is 30 wt% ( In the case of the mark (■ in FIG. 7), the blending ratio of about 2700 MPa and the trifunctional acrylic monomer is 50 wt% (marked in FIG. 7), which is about 4500 MPa, as the blending ratio of the trifunctional acrylic monomer increases. It can be seen that the elastic modulus of the ultraviolet curable resin increases. When an ultraviolet curable resin having an elastic modulus exceeding 2500 MPa is used for an optical recording medium, there is a problem that the optical recording medium itself warps due to its high elastic modulus. It is not preferable to use it. From this, the upper limit of the mixing ratio of the trifunctional acrylic monomer is 20 wt%.

From FIG. 8, the integrated light quantity at which the transmittance of the organic dye layer formed on the test substrate is constant is 200 mj / cm ^{2 when} the mixing ratio of the trifunctional acrylic monomer is 0 wt% (marked with ◆ in FIG. 8). On the other hand, when the blending ratio of the trifunctional acrylic monomer is 5 wt% (marked with a circle in FIG. 8), 150 mj / cm ² , and when the blending ratio of the trifunctional acrylic monomer is 10 wt% (marked with a circle in FIG. 8), 120 mj / cm ² . It can be seen that as the curing end point of No. 7 is increased, the blending ratio of the trifunctional acrylic monomer increases.

  Further, the transmittance after the end point of curing of the organic dye layer formed on the test substrate is about 13% when the blending ratio of the trifunctional acrylic monomer is 0 wt% (marked with a ♦ in FIG. 8), and the trifunctional acrylic. When the monomer blending ratio is 5 wt% (marked in FIG. 8), it is about 5%, and when the blending ratio of trifunctional acrylic monomer is 20 wt% (△ mark in FIG. 8), it is approximately 2.5%. It can be seen that the ratio decreases as the ratio increases. If the increase in the transmittance of the organic dye layer is 10% or less, the recording characteristics of the optical recording medium are not adversely affected. Therefore, the lower limit of the mixing ratio of the trifunctional acrylic monomer is 5 wt%, preferably 10 wt%.

From these facts, the ultraviolet curable resin in which the ratio of the trifunctional acrylic monomer is 5 wt% to 20 wt%, preferably 10 wt% to 20 wt%, with respect to the total weight of the bifunctional acrylic monomer and the trifunctional acrylic monomer The curing end point is reached in a short time and completely cured with a small amount of UV irradiation with an integrated light quantity of 100 mj / cm ^{2 to} 150 mj / cm ² . For this reason, the contact time between the uncured UV curable resin and the organic dye layer is short, and there is almost no chemical change in the organic dye of the organic dye layer. Therefore, by using this ultraviolet curable resin for the optical recording media 50 and 60 according to the present invention, it is possible to suppress an increase in the transmittance of the organic dye layer in contact with the ultraviolet curable resin.

  In the substrate manufacturing step, a first substrate 1 and a second substrate 5 made of polycarbonate each having a predetermined uneven pattern formed on one side and having a thickness of 0.6 mm were manufactured by an injection molding method. Next, in the information recording layer forming step, an Al (aluminum) reflective layer 2 having a thickness of 100 nm was formed on the uneven pattern of the first substrate 1 by a sputtering method. Next, phthalocyanine organic dye red 2 dissolved in 1 wt% in ethanol is applied onto the reflective layer 2 of the first substrate 1 using a spin coater under a condition of a rotation speed of 2000 rpm so that the film thickness becomes 80 nm. 1 Organic dye layer 3 was formed. Thereby, the first information recording layer 4 was formed on the first substrate 1.

Next, phthalocyanine-based organic dye red 2 dissolved in 1 wt% in ethanol is applied on the uneven pattern of the second substrate 5 manufactured in the substrate manufacturing process using a spin coater so that the film thickness becomes 80 nm. Two organic dye layers 6 were formed. Next, a 120-nm-thick SiO ₂ transflective layer 7 was formed on the second organic dye layer 6 of the second substrate 5 by sputtering. Thereby, the second information recording layer 8 is formed on the second substrate 5.

  Next, trimethylolpropane trimethacrylate, which is a trifunctional acrylic monomer, is blended at a blending ratio of 20 wt%, and a bisphenol AEO adduct diacrylate, which is a bifunctional acrylic monomer, is blended at a blending ratio of 80 wt%. 4 wt% of hydroxysilphenyl ketone as a photoinitiator was added to the total weight of the mixture with the bifunctional acrylic monomer to prepare an ultraviolet curable resin.

In the ultraviolet curing resin curing step, the produced ultraviolet curing resin was applied on the second information recording layer 8 of the second substrate 5 using a spin coater under a condition of a rotation speed of 700 rpm so that the layer thickness was about 50 μm. Next, the ultraviolet curable resin applied to the second substrate 5 and the first information recording layer 4 of the first substrate 1 are brought into close contact with each other, and ultraviolet rays are irradiated so that the integrated light amount becomes 150 mj / cm ^2. Was cured. As a result, the ultraviolet curable resin layer 10 is formed, and the first substrate 1 having the first information recording layer 4 and the second substrate 5 having the second information recording layer 8 are bonded to form two information recording layers. An optical recording medium 50 having the same was produced. In addition, a laser beam having a wavelength of 515 nm of the first organic dye layer 3 of the transmittance measuring disc produced in the same manner as in Example 1 except that the reflective layer 2, the semi-transmissive reflective layer 7 and the second organic dye layer 6 are not formed. The transmittance of the first organic dye layer 3 was 2.5% when the transmittance was measured using a spectrophotometer.

  When information signals were recorded and reproduced on the first information recording layer 4 of the produced optical recording medium 50, good recording characteristics and reproduction characteristics were obtained.

  In the substrate manufacturing process, a first substrate 1 made of polycarbonate having a thickness of 1.1 mm and having a predetermined concavo-convex pattern formed on one surface was manufactured by an injection molding method. Next, in the first information recording layer forming step, an Al (aluminum) reflective layer 2 having a film thickness of 100 nm was formed on the concavo-convex pattern of the first substrate 1 using a sputtering method. Next, phthalocyanine-based organic dye red 2 dissolved in 1 wt% in ethanol is applied on the reflective layer 2 of the first substrate 1 so as to have a film thickness of 80 nm using a spin coater, and the first organic dye layer 3 is applied. Formed. Thereby, the first information recording layer 4 is formed on the first substrate 1.

  Next, trimethylolpropane trimethacrylate, which is a trifunctional acrylic monomer, is blended at a blending ratio of 5 wt%, and bisphenol AEO adduct diacrylate, which is a bifunctional acrylic monomer, is blended at a blending ratio of 95 wt%. 4 wt% of hydroxysilphenyl ketone as a photoinitiator was added to the total weight of the mixture with the bifunctional acrylic monomer to prepare an ultraviolet curable resin.

The produced ultraviolet curable resin was applied on the first information recording layer 4 of the first substrate 1 so as to have a layer thickness of about 50 μm using a spin coater in the ultraviolet curable resin curing step. The ultraviolet curable resin is irradiated by irradiating the applied ultraviolet curable resin with ultraviolet rays so that the integrated light quantity becomes 150 mj / cm ² while closely contacting the nickel stamper 20 on which the master pattern of the concavo-convex pattern having a predetermined dimension is formed. After curing, the stamper 20 was peeled off. Thereby, the ultraviolet curable resin layer 10a which has an uneven | corrugated pattern of a predetermined dimension on one side is formed.

Next, in the second information recording layer forming step, a SiO ₂ transflective layer 7 having a film thickness of 120 nm was formed on the concave / convex pattern of the ultraviolet curable resin layer 10a by sputtering. Next, phthalocyanine-based organic dye red 2 dissolved in 1 wt% in ethanol is applied on the semi-transmissive reflective layer 7 of the ultraviolet curable resin layer 10a so as to have a film thickness of 80 nm using a spin coater, and the second organic dye layer 6 was formed. Thereby, the second information recording layer 8 is formed on the ultraviolet curable resin layer 10a.

  Next, in the light transmitting layer forming step, a light transmitting layer 12 is formed by bonding a polycarbonate film having a thickness of 0.1 mm on the second information recording layer 8 to form a light having two information recording layers. A recording medium 60 was produced. In addition, a laser beam having a wavelength of 515 nm of the first organic dye layer 3 of the transmittance measuring disk produced in the same manner as in Example 2 except that the reflective layer 2, the semi-transmissive reflective layer 7 and the second organic dye layer 6 are not formed. The transmittance of the first organic dye layer 3 was 5% when the transmittance was measured using a spectrophotometer.

  When information signals were recorded and reproduced on the first information recording layer 4 of the produced optical recording medium 60, good recording characteristics and reproduction characteristics were obtained.

  From the above, the optical recording medium according to the present invention can suppress an increase in the transmittance of the organic dye layer by optimizing the composition of the ultraviolet curable resin, and can obtain good recording / reproducing characteristics. it can.

  Further, according to the method for producing an optical recording medium according to the present invention, an optical recording medium having a low transmittance of the organic dye layer and good recording / reproducing characteristics can be produced with high productivity.

  In this example, the phthalocyanine organic dye red 2 is used as the organic dye. However, the transmittance of organic dye layers using cyanine, phthalocyanine, azo, and other organic dyes is also shown. It is possible to obtain the same effect that suppresses the increase of. In addition, the present invention can be modified and implemented without departing from the gist of the present invention.

1 is a schematic cross-sectional view of an optical recording medium according to a first embodiment of the present invention. It is a schematic cross section of the optical recording medium of the 2nd form which concerns on this invention. It is a figure explaining the outline of the manufacturing method of the optical recording medium of the 1st form which concerns on this invention. It is a figure explaining the outline of the manufacturing method of the optical recording medium of the 2nd form which concerns on this invention. It is a figure which shows the relationship between an integrating | accumulating light quantity and an elasticity modulus when the compounding ratio of the monofunctional acrylic monomer of a ultraviolet curable resin and a bifunctional acrylic monomer is changed. It is a figure which shows the relationship between the integrated light quantity when the compounding ratio of the monofunctional acrylic monomer of a ultraviolet curable resin and a bifunctional acrylic monomer is changed, and the transmittance | permeability of an organic pigment layer. It is a figure which shows the relationship between an integrating | accumulating light quantity and an elasticity modulus when the compounding ratio of the bifunctional acrylic monomer and trifunctional acrylic monomer of the ultraviolet curable resin which concerns on this invention is changed. It is a figure which shows the relationship between the integrated light quantity and the transmittance | permeability of an organic pigment | dye layer when the compounding ratio of the bifunctional acrylic monomer and trifunctional acrylic monomer of the ultraviolet curable resin which concerns on this invention is changed.

Explanation of symbols

1 First substrate
2 Reflective layer
3 First organic dye layer
4 First information recording layer
5 Second substrate
6 Second organic dye layer
7 Transflective layer
8 Second information recording layer
10, 10a UV curable resin layer
12 Light transmission layer
50, 60 optical recording media

Claims (3)

An optical recording medium,
A substrate,
An organic dye layer formed on the substrate for recording information signals;
An ultraviolet curable resin layer formed on the organic dye layer in contact with the organic dye layer;
Have
The optical recording medium, wherein the ultraviolet curable resin layer is a layer obtained by curing an ultraviolet curable resin containing a bifunctional acrylic monomer and a trifunctional acrylic monomer. The ratio of the trifunctional acrylic monomer in the ultraviolet curable resin before curing is in the range of 5% by weight to 20% by weight with respect to the total weight of the bifunctional acrylic monomer and the trifunctional acrylic monomer. The optical recording medium according to claim 1. An optical recording medium manufacturing method comprising:
An organic dye layer forming step of forming an organic dye layer on the substrate;
After the organic dye layer forming step, an ultraviolet curable resin containing a bifunctional acrylic monomer and a trifunctional acrylic monomer is applied to the surface of the organic dye layer, and the applied ultraviolet curable resin is irradiated with ultraviolet rays to form the ultraviolet curable resin. UV curing resin curing process to cure the resin,
Have
In the ultraviolet curable resin curing step, the ratio of the trifunctional acrylic monomer in the ultraviolet curable resin before curing is 5% by weight to 20% by weight with respect to the total weight of the bifunctional acrylic monomer and the trifunctional acrylic monomer. A method for producing an optical recording medium, characterized in that the integrated light quantity of ultraviolet rays applied to the ultraviolet curable resin is within a range of 100 mj / cm ^{2 to} 150 mj / cm ² .

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