JP2005203032A - Method for manufacturing multilayer structure optical recording medium, and light-transmitting stamper - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for manufacturing a multilayer structure optical recording medium by a photopolymerization method (2P method) in which efficiency is improved. <P>SOLUTION: In the method for manufacturing the multilayer structure optical recording medium 100 in which a second recording layer 105 is laminated on a first recording layer 102 formed on a first substrate 101 made of a polycarbonate resin via a resin layer 104 formed using an ultraviolet curing resin, the resin layer 104 provided between the two recording layers is formed by a photopolymerization method (2P method) using a light transmitting stamper 110 made of glass having a nickel layer 111 in which the surface is subjected to plasma treatment and the releasing properties from the resin layer 104 are improved. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a method for manufacturing a multilayer structure optical recording medium, and more particularly to a method for manufacturing a multilayer structure optical recording medium using a light transmissive stamper.

In recent years, in order to record and reproduce a large amount of data for a long time, a multi-layer structure optical recording medium has been developed in which two or more recording layers or signal layers are provided on one medium. A DVD (Digital Versatile Disk) -R, which is an example of such a multi-layer structure optical recording medium, has a recording layer or a signal layer on one side, and each recording layer or recording layer via an ultraviolet curable adhesive layer. It is manufactured by pasting together so that the signal layers face each other.
On the other hand, when a laser beam having a short wavelength such as Blu-ray is used for recording / reproducing with the recent increase in the density of optical discs, the depth of focus of the objective lens becomes shallow, the tilt of the substrate and Due to the thickness variation, the objective lens is likely to generate aberration. For this reason, it has become necessary to thin the substrate through which the recording / reproducing laser beam passes. For example, in the case of a Blu-ray Disk, a structure in which two or more recording layers or signal layers are laminated in a thickness of 0.1 mm is required. It is considered difficult.
Thus, as a method for producing such a Blu-ray Disk, a production method called a photopolymerization method (hereinafter referred to as “2P method”) has been developed. According to the 2P method, for example, an ultraviolet curable resin material is applied on a recording layer or a signal layer formed on a substrate made of a light transmissive material, usually via another layer such as a reflective layer. Then, a metal stamper having a fine information / recording pattern is placed thereon, then the UV curable resin material is cured by ultraviolet rays irradiated from the substrate side, and then the metal stamper is peeled off, and the information / recording pattern is formed on the surface. A resin layer to which is transferred is formed. Thereafter, a second recording layer or signal layer is formed on the resin layer, and a multilayer structure optical recording medium is manufactured (see Patent Document 1).

Japanese Patent Laid-Open No. 08-306067

By the way, in the 2P method, the ultraviolet curable resin raw material applied on the recording layer or the signal layer is cured by ultraviolet rays irradiated from the substrate side made of a light transmissive material to form a resin layer. At this time, since another layer such as a reflective layer is usually formed on the recording layer or signal layer, there is a problem that it is difficult to transmit ultraviolet rays irradiated from the substrate side. For this reason, as the number of recording layers or signal layers to be stacked increases, the transmittance of ultraviolet rays decreases, and it becomes difficult to cure the ultraviolet curable resin material.
Further, in the case of the 2P method, it is necessary to smoothly peel off the stamper after the ultraviolet curable resin material is cured. However, depending on the type of UV curable resin, the UV curable resin is hardened while the stamper is in close contact, or the UV curable resin and the stamper are not easily peeled off, or even if peeled, the surface of the resin layer is uniform. Manufacturing problems such as lowering have occurred.

The present invention has been made to solve the technical problem that has emerged when manufacturing a multilayer optical recording medium by the 2P method.
That is, an object of the present invention is to provide a method of manufacturing a multilayer structure optical recording medium with improved manufacturing efficiency.
Another object of the present invention is to provide a stamper used when manufacturing a multilayer structure optical recording medium by the 2P method.

In order to solve this problem, in the present invention, a light-transmitting stamper with improved releasability from a cured ultraviolet curable resin is used in a method for producing a multilayer structure optical recording medium by the 2P method. . That is, a method for producing a multilayer structure optical recording medium to which the present invention is applied includes a step of applying a photocurable resin layer directly or via another layer on a recording layer or a signal layer formed on a substrate. A light transmissive stamper having an uneven shape with a nickel layer formed on the surface of the light curable resin layer is placed on the coated light curable resin layer, and light is irradiated from the light transmissive stamper side. A step of forming a resin layer obtained by curing the photocurable resin layer, and a step of peeling the formed resin layer and the light transmissive stamper and transferring the uneven shape to the resin layer. To do.
Here, if the light transmissive stamper is characterized in that the surface of the nickel layer is subjected to plasma treatment, the resin layer formed of an ultraviolet curable resin or the like and the light transmissive stamper are subjected to an unreasonable load. It can be easily peeled off without applying. As a result, deformation of the recording layer and the resin layer is prevented. The nickel layer is preferably subjected to plasma treatment with oxygen gas and / or fluorocarbon gas. Furthermore, the manufacturing efficiency of the multilayer optical recording medium can be improved by repeating the process of forming another recording layer or signal layer directly or via another layer on the resin layer thus formed. it can.

Next, the present invention provides a method for producing a multilayer structure optical recording medium in which at least one other recording layer or signal layer is formed on a recording layer or signal layer formed on a substrate via a resin layer. The multilayered optical recording medium is characterized in that the resin layer is formed by a photopolymerization method using a light-transmitting stamper whose surface has been subjected to a treatment for improving releasability from the resin layer. It is grasped as a manufacturing method.
Here, if the light transmissive stamper is formed from a glass substrate having a nickel layer formed on the surface by sputtering or vapor deposition, the resin layer is formed by light irradiated from the light transmissive stamper side. Can be formed. At this time, it is preferable that a resin layer consists of photocurable resin.

On the other hand, the present invention is a stamper used in a method for producing a multilayer structure optical recording medium having a step of forming a resin layer by a photopolymerization method. It is understood as a light transmissive stamper characterized by comprising a glass substrate on which a nickel layer is formed so that the transmittance is 30% or more.
Here, the thickness of the nickel layer is preferably 20 nm to 50 nm. Furthermore, it is preferable that the surface of the nickel layer is subjected to plasma treatment using oxygen gas and / or fluorocarbon gas.

  Thus, according to the present invention, the manufacturing efficiency of the multilayer structure optical recording medium by the 2P method is improved.

Hereinafter, the best mode for carrying out the present invention (hereinafter referred to as an embodiment of the present invention) will be described in detail.
FIG. 1 is a diagram for explaining a method of manufacturing a multilayer optical recording medium to which the present embodiment is applied. FIG. 1 shows a method for manufacturing a multilayer optical recording medium having two recording layers or signal layers as an example of a method for manufacturing a multilayer optical recording medium.
A multilayer-structure optical recording medium 100 shown in FIG. 1 (f) includes a disk-shaped first substrate 101 formed of a light-transmitting material such as polycarbonate, and a first recording layer 102 on the first substrate 101. A translucent first reflective layer 103, a light transmissive resin layer 104 made of an ultraviolet curable resin, a second recording layer 105, a second reflective layer 106, and a protective layer 107 forming the outermost layer. However, it has the structure laminated | stacked in order. Concavities and convexities are formed on the first substrate 101 and the resin layer 104, respectively, and constitute recording tracks. Recording / reproduction of optical information on the multilayer optical recording medium 100 is performed by laser light 108 irradiated on the first recording layer 102 and the second recording layer 105 from the first substrate 101 side.

As shown in FIG. 1A, a first substrate 101 made of polycarbonate having grooves, lands, and pre-pits formed on the surface with irregularities is manufactured by injection molding or the like using a nickel stamper or the like. Next, the first recording layer 102 is formed on the surface of the first substrate 101 having the unevenness. After forming the first recording layer 102, the first reflective layer 103 is formed on the first recording layer 102 by sputtering or vapor-depositing an Ag alloy or the like.
Subsequently, as shown in FIG. 1B, an ultraviolet curable resin material is applied to the entire surface of the first reflective layer 103 by spin coating or the like to form an ultraviolet curable resin material layer 104a.
Next, as shown in FIG. 1C, a glass light-transmitting stamper 110 having a concavo-convex shape in which a nickel layer 111 is formed on the surface facing the ultraviolet curable resin raw material layer 104a is ultraviolet curable. It is placed on the resin raw material layer 104a and pressed so that the thickness of the ultraviolet curable resin raw material layer 104a is 25 μm. In this state, ultraviolet rays are irradiated from the light transmissive stamper 110 side through the light transmissive stamper 110. Then, the UV curable resin is cured, and when the UV curable resin is sufficiently cured, the light transmissive stamper 110 is peeled off, and the resin layer 104 in which the unevenness of the light transmissive stamper 110 is transferred to the surface of the UV curable resin (FIG. 1 ( d)).
Subsequently, as shown in FIG. 1D, a second recording layer 105 is formed on the resin layer 104. Then, as shown in FIG. 1E, the second reflective layer 106 is formed on the second recording layer 105 by sputtering vapor deposition of Ag alloy or the like. Thereafter, as shown in FIG. 1 (f), an ultraviolet curable resin is applied on the second reflective layer 106 by, for example, a spin coating method, and then cured to form a protective layer 107 having a thickness of 75 μm. The production of the medium 100 is completed.
In addition, when the recording layer is further laminated, the operation of curing the ultraviolet curable resin using the light transmissive stamper 110 is repeated.

Next, the light transmissive stamper 110 will be described. FIG. 2 is a diagram illustrating the light transmissive stamper 110. The light transmissive stamper 110 shown in FIG. 2 has a light transmissive glass substrate 112 having grooves and lands and prepits formed on the surface with irregularities, and a nickel layer 111 formed on the surface of the irregularities. ing. The uneven shape formed on the surface of the glass substrate 112 has a shape obtained by inverting the uneven shape formed on the surface of the first substrate 101 of the multilayer optical recording medium 100. The thickness of the glass substrate 112 is usually 0.5 mm to 6 mm.
The nickel layer 111 is formed, for example, by sputtering nickel on the uneven surface of the glass substrate 112. The thickness of the nickel layer 111 is usually 20 nm to 50 nm. If the thickness of the nickel layer 111 is in this range, the light transmittance of the glass substrate 112 is 30% or more, and has sufficient light transmittance. It is possible to efficiently cure the functional resin and improve productivity. By forming the nickel layer 111 on the uneven surface, the resin layer 104 (FIG. 1D) formed by curing the light transmissive stamper 110 and the UV curable resin raw material layer 104a (FIG. 1C). ) Is significantly improved, and the light transmissive stamper 110 can be easily peeled without applying an excessive load on the resin layer 104 (FIG. 1D).

  In the present embodiment, the light transmissive stamper 110 is preferably subjected to plasma treatment on the surface of the nickel layer 111. By performing plasma treatment on the surface of the nickel layer 111, the releasability between the light transmissive stamper 110 and the resin layer 104 (FIG. 1D) is further improved. The gas used in the plasma treatment is not particularly limited, but usually a fluorocarbon gas such as oxygen or carbon tetrafluoride is used. The plasma treatment can be performed either when these gases are used alone or when both of these gases are used. By performing the plasma treatment, oxygen atoms or fluorine atoms are added to the surface of the nickel layer 111 to form, for example, NiOx, NiFx or the like.

  In the present embodiment, the surface energy of the light transmissive stamper 110 is reduced by performing plasma treatment on the light transmissive stamper 110. The measured value of critical surface tension (unit: dyn / cm), which is an index of surface energy, is 42 in the glass substrate 112, but is reduced to 40 in the plasma-treated nickel layer 111, and the surface of the ultraviolet curable resin is reduced. The difference from the tension (46) is large. This further improves the releasability between the light transmissive stamper 110 and the resin layer 104 (FIG. 1D), and the resin layer 104 and the light transmissive stamper 110 are easily peeled off without applying an excessive load. be able to. In addition, the manufacturing efficiency of the multilayer optical recording medium 100 is improved, such as the possibility that the first recording layer 102 and the first reflective layer 103 are deformed is reduced.

Next, each layer constituting the multilayer optical recording medium 100 shown in FIG. 1 (f) will be briefly described.
(First substrate)
It is desirable that the first substrate 101 has optical properties such as light transmittance and low birefringence. Moreover, it is desirable that the moldability is excellent, such as easy injection molding. Furthermore, it is desirable that the hygroscopicity is small. Furthermore, it is desirable to provide shape stability so that the multilayer structure optical recording medium has a certain degree of rigidity. The material constituting the first substrate 101 is not particularly limited. For example, acrylic resin, methacrylic resin, polycarbonate resin, polyolefin resin (particularly amorphous polyolefin), polyester resin, polystyrene resin, and epoxy resin. And glass. The thickness of the 1st board | substrate 101 is 10 micrometers-2 mm normally, Preferably it is about 600 micrometers.

(First recording layer)
The first recording layer 102 is, for example, an organic dye material having a maximum absorption wavelength λmax in the visible light to near infrared region of about 350 nm to 900 nm and suitable for recording with a blue to near microwave laser; an amorphous state and a crystal Examples thereof include a phase change recording material in which a recording information signal is detected using a reflectance difference and a phase difference change caused by a difference in refractive index from the state. Examples of the organic dye material include phthalocyanine dyes, cyanine dyes, anthraquinone dyes, and the like. Examples of the phase change recording material include SbTe, GeTe, GeSbTe, InSbTe, AgSbTe, and AgInSbTe. The thickness of the first recording layer 102 is not particularly limited, but is usually 5 nm to 3 μm. A method for forming the first recording layer 102 is not particularly limited, and generally includes a thin film forming method that is generally performed such as a vacuum deposition method, a sputtering method, a doctor blade method, a casting method, a spin coating method, and an immersion method. It is done.

(First reflective layer)
The material constituting the first reflective layer 103 is not particularly limited. For example, Au, Al, Ag, Cu, Ti, Cr, Ni, Pt, Ta, Pd, Mg, Se, Hf, V, Nb, Ru , W, Mn, Re, Fe, Co, Rh, Ir, Zn, Cd, Ga, In, Si, Ge, Te, Pb, Po, Sn, Bi, and the like. The thickness of the first reflective layer 103 is usually 3 nm to 50 nm. Examples of the method for forming the first reflective layer 103 include sputtering, ion plating, chemical vapor deposition, and vacuum vapor deposition.

(Resin layer)
Examples of the photocurable resin constituting the resin layer 104 include radical ultraviolet curable resins and cationic ultraviolet curable resins, and any of them can be used. As the radical ultraviolet curable resin, monofunctional (meth) acrylate and polyfunctional (meth) acrylate can be used as polymerizable monomer components. Examples of the cationic ultraviolet curable resin include an epoxy resin containing a cationic polymerization type photoinitiator.

(Second recording layer)
The second recording layer 105 may be the same as or different from the material used for the first recording layer 102 described above. The material constituting the second recording layer 105, the film forming method, and the like are described in the same manner as the first recording layer 102, and the wet film forming method is preferable as the film forming method. The film thickness of the second recording layer 105 is usually 10 nm to 3 μm.
(Second reflection layer)
The material constituting the second reflective layer 106, the film forming method, and the like will be described in the same manner as the first reflective layer 103. The thickness of the second reflective layer 106 is usually 20 nm to 400 nm. In addition, an inorganic or organic resin layer or adhesive layer may be provided above and below the second reflective layer 106 in order to improve reflectivity, improve recording characteristics, and improve adhesion.
(Second board)
The protective layer 107 preferably has high mechanical stability. Examples of such a material include the same materials that can be used for the first substrate 101. Moreover, photocurable resins, such as ultraviolet curable resin, etc. are mentioned. The thickness of the protective layer 107 is 0.3 mm to 3 mm.

It is a figure explaining the manufacturing method of a multilayer structure optical recording medium. It is a figure explaining a light transmissive stamper.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 ... Multi-layer structure optical recording medium, 101 ... 1st board | substrate, 102 ... 1st recording layer, 103 ... 1st reflection layer, 104 ... Resin layer, 104a ... Ultraviolet curable resin raw material layer, 105 ... 2nd recording layer, 106 ... Second reflective layer, 107 ... Protective layer, 108 ... Laser light, 110 ... Light transmissive stamper, 111 ... Nickel layer, 112 ... Glass substrate

Claims (10)

A step of applying a photocurable resin layer directly or via another layer on the recording layer or signal layer formed on the substrate;
On the applied photocurable resin layer, a light transmissive stamper having a concavo-convex shape having a nickel layer formed on the surface of the photocurable resin layer is placed, and light is transmitted from the light transmissive stamper side. Forming a resin layer by irradiating and curing the photocurable resin layer; and
And a step of peeling the formed resin layer and the light transmissive stamper, and transferring the uneven shape to the resin layer.   2. The method of manufacturing a multilayer optical recording medium according to claim 1, wherein the light transmissive stamper is subjected to plasma treatment on a surface of the nickel layer.   3. The method for producing a multilayer optical recording medium according to claim 2, wherein the nickel layer is subjected to the plasma treatment with oxygen gas and / or fluorocarbon gas.   2. A method of manufacturing a multilayer optical recording medium according to claim 1, further comprising a step of further forming another recording layer or a signal layer on the resin layer directly or via another layer. In the method of manufacturing a multilayer structure optical recording medium in which at least one other recording layer or signal layer is formed on a recording layer or signal layer formed on a substrate via a resin layer,
The multilayered optical recording is characterized in that the resin layer is formed by a photopolymerization method using a light-transmitting stamper whose surface has been treated to improve releasability from the resin layer. A method for manufacturing a medium.   6. The method of manufacturing a multilayer optical recording medium according to claim 5, wherein the light transmissive stamper is formed from a glass substrate having a nickel layer formed on a surface thereof by sputtering or vapor deposition.   6. The method for producing a multilayer optical recording medium according to claim 5, wherein the resin layer is made of a photocurable resin. A stamper used in a method for producing a multilayer structure optical recording medium having a step of forming a resin layer by a photopolymerization method,
The light-transmitting stamper is characterized in that the stamper is made of a glass substrate on which a nickel layer is formed so that the light transmittance is 30% or more on the surface facing the resin layer.   9. The light transmissive stamper according to claim 8, wherein the nickel layer has a thickness of 20 nm to 50 nm.   9. The light transmissive stamper according to claim 8, wherein the surface of the nickel layer is subjected to plasma treatment using oxygen gas and / or fluorocarbon gas.

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