JP2007026566A - Optical information recording medium and manufacturing method thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical information recording medium capable of easily forming a flat cover layer at low cost and a method for producing the same.
SOLUTION: A base material 1 on which a recording layer 2 is formed and a mold material 11 face each other, and the liquid coating agent 4 is spread between the base material 1 and the mold material 11 by centrifugal force generated by rotating them. Thus, a cover layer along the surface of the mold material 11 is formed on the surface of the recording layer 2, and then the cover layer is peeled from the mold material 11.
[Selection] Figure 4

Description

  The present invention relates to an optical information recording medium such as a Blu-ray disc and a manufacturing method thereof.

As optical information recording media, CDs, DVDs, and the like are widely used. In recent years, Blu-ray discs with larger capacities have been developed and put into practical use. Note that the Blu-ray Disc is a standard name.
FIG. 10 shows an example of an optical information recording medium. In this optical information recording medium, a recording layer 2 made of an Ag—Bi alloy or the like is provided on the surface of a flat substrate 1, and an optical information recording medium is formed on the surface. A permeable cover layer 15 is formed.
In this optical information recording medium, reading light can be incident on the recording layer 2 through the cover layer 15 to read information on the recording layer 2.
If the cover layer 15 is formed too thin, the reading accuracy is likely to decrease due to deposits and scratches on the surface, and thus the cover layer 15 is formed sufficiently thick (for example, 50 μm or more in thickness).

A spin coating method is widely used as a method for forming a layer on a flat substrate. In the spin coating method, a layer is formed on the surface of the substrate by rotating the substrate at a high speed and spreading the coating agent by centrifugal force.
However, in the spin coating method, since the coating agent is spread by centrifugal force, the outer peripheral portion tends to be thicker than the inner peripheral portion.
In the optical information recording medium, since the cover layer 15 is formed thick, when the spin coating method is employed, the difference in thickness between the inner peripheral portion and the outer peripheral portion of the cover layer 15 is increased, and the reading accuracy is increased. There was a risk of lowering.
For this reason, a manufacturing method that can achieve uniform cover layer thickness has been proposed (see Patent Document 1). In this manufacturing method, the coating agent is supplied to the surface of the base material so that the coating amount of the coating agent that is the material of the cover layer is constant per area, and the spreading agent is not spread and applied by the leveling action of the coating agent. Flatten.
In Patent Document 1, as a method of supplying the coating agent so that the coating amount of the coating agent is constant per substrate area, using a discharge unit having a plurality of nozzle portions with different discharge amounts, the inner periphery of the substrate The method of rotating a base material at low speed is mentioned, supplying a coating agent so that the coating amount may increase from the side to the outer peripheral side.
JP 2004-73969 A

However, in the above prior art, in order to supply the coating agent so that the coating amount of the coating agent is constant per substrate area, a complicated apparatus is required, which is disadvantageous in terms of cost. There is also a problem that it is difficult to accurately determine the supply amount of the coating agent.
The present invention has been made in view of the above circumstances, and an object of the present invention is to provide an optical information recording medium capable of easily forming a flat cover layer at low cost and a method for manufacturing the same.

  An optical information recording medium manufacturing method according to the present invention includes a base material, a recording layer provided on one surface of the base material, and a light-transmitting cover layer that covers the recording layer, and passes through the cover layer. A method for producing an optical information recording medium capable of reading the recording layer, wherein the base material on which the recording layer is formed and a mold material are faced to each other, and the liquid application is performed by centrifugal force generated by rotating them. By spreading an agent between the base material and the mold material, the cover layer along the mold material surface is formed on the recording layer surface, and then the cover layer is peeled off from the mold material.

According to the method for producing an optical information recording medium of the present invention, a flat cover layer along the surface of the mold material is easily formed on the surface of the recording layer by spreading a liquid coating agent between the base material and the mold material. be able to.
Further, since the operation is easy, there is no disadvantage in terms of manufacturing cost.
Further, by reusing the mold material, it is possible to reduce the manufacturing cost.

In the method for producing an optical information recording medium of the present invention, the mold material may include a mold material body and a peelable coating layer provided on the surface thereof. Thereby, the cover layer can be easily peeled from the mold material.
The viscosity of the coating agent is preferably 1500 to 3000 mPa · s (25 ° C.).
The number of rotations when rotating the base material and the mold material is preferably 1000 to 3000 min- ¹ .
In order to peel the cover layer from the mold material, a method of feeding a peeling gas between the cover layer and the mold material is possible.
The optical information recording medium of the present invention is an optical information recording medium obtained by the above production method.

With reference to FIGS. 1-8, an example of the manufacturing method of the optical information recording medium of this invention is demonstrated.
As shown in FIGS. 1 and 2, a disk-shaped mold material 11 in which a peelable coating layer 3 is formed on the surface of a mold material body 12 is prepared.
As the mold body 12, for example, one made of polycarbonate, polyethylene, polypropylene or the like can be used.
As the peelable coating layer 3, one having a peelability with respect to the cover layer 5 (described later) higher than the peelability with respect to the mold material main body 12 is used.

The peelable coating layer 3 is preferably made of a polysiloxane composition containing a base agent and polysiloxane.
As the base agent, it is preferable to use a photopolymerizable composition containing a photopolymerizable compound, a photopolymerization initiator, and a polycarbonate-soluble monomer.
As the photopolymerizable compound, trimethylolpropane ethylene oxide-modified triacrylate (TMP (EO) TA) is preferable. TMP (EO) TA is an acrylate of triol obtained by adding 3 mol of ethylene oxide to 1 mol of trimethylolpropane, for example.
As the photopolymerization initiator, 1-hydroxycyclohexyl phenyl ketone (HCPK) is suitable.
As the polycarbonate-soluble monomer, neopentyl glycol diacrylate (NPGDA) is preferable.
Specifically, examples include 80 parts by mass of TMP (EO) TA, 10 parts by mass of HCPK, 10 parts by mass of NPGDA, and 2.5 parts by mass of polysiloxane.

For example, a spin coat method can be used to form the peelable coat layer 3.
That is, the polysiloxane composition is applied to the inner peripheral portion of the mold body 12 and the mold body 12 is rotated (spun), thereby spreading the polysiloxane composition on the surface of the mold body 12.
Next, the peelable coat layer 3 is obtained by irradiating ultraviolet rays using a high pressure mercury lamp to cure the polysiloxane composition.
The thickness of the peelable coating layer 3 can be 10 μm or less, for example, 2 to 10 μm. When the thickness is within this range, the difference in thickness between the inner peripheral portion and the outer peripheral portion is reduced, and the peelable coating layer 3 can be formed more flatly.
The mold material may be configured not to have a peelable coating layer.

As shown in FIG. 3, a liquid coating agent 4 is supplied to the surface of the peelable coating layer 3.
As the coating agent 4, one capable of forming a light-transmitting cover layer 5 is used. The coating agent 4 is in a state that can flow at the time of coating, and can be cured as necessary. For example, an ultraviolet curable resin, a thermosetting resin, or the like can be used.
Specific examples of the coating agent 4 include an ultraviolet curable resin composition containing epoxy (meth) acrylate and urethane (meth) acrylate.
Examples of the epoxy (meth) acrylate include those represented by the formula (I).

Urethane (meth) acrylate is, for example, (i) HO- (RO) nH (wherein R represents an alkylene group having 2 to 24 carbon atoms which may have a branched chain, and n is an integer of 1 or more) And a compound having a molecular weight of 50 to 4000, (ii) a diisocyanate compound, and (iii) a compound having one hydroxyl group and one radical polymerizable unsaturated bond in the same molecule. A compound.
The elastic modulus of the cured film at 25 ° C. after curing of the ultraviolet curable composition is preferably 100 to 800 MPa.

The viscosity of the coating agent 4 is 1500 mPa · s (25 ° C.) or more, preferably 2000 mPa · s (25 ° C.) or more. By setting the viscosity within this range, the cover layer 5 having a sufficient thickness can be easily formed. If the viscosity is too low, the coating agent 4 tends to be washed away by centrifugal force when the cover layer 5 is formed.
The viscosity of the coating agent 4 is preferably 3000 mPa · s (25 ° C.) or less because handling becomes difficult if the viscosity is too high.

  The coating agent 4 may be supplied only to a part of the mold material 11, not the whole. For example, an annular portion can be supplied along the circumferential direction of the mold material 11 to a portion near the inner periphery of the mold material 11.

As shown in FIG. 4, a base material 1 having a recording layer 2 made of silver, a silver alloy (for example, an Ag—Bi alloy) or the like on the surface is prepared.
Although it does not specifically limit as the base material 1, The thing which consists of a polycarbonate, polyolefin, etc. can be used, and what consists of a polycarbonate excellent in durability especially is preferable. The substrate 1 is preferably light transmissive.
The base material 1 faces the mold material 11 so as to be parallel to the mold material 11.
At this time, the position of the substrate 1 is determined so that the distance between the recording layer 2 and the peelable coating layer 3 is the thickness of the cover layer 5 to be formed. For example, the cover layer 5 can have a thickness of 50 to 200 μm.

As shown in FIGS. 4 and 5, by rotating the base material 1 and the mold material 11 in the circumferential direction, the coating agent 4 spreads outward according to the centrifugal force.
At this time, the coating agent 4 spreads along the surface of the peelable coat layer 3 and becomes a flat shape in accordance with the surface shape of the peelable coat layer 3.
The rotation speed of the base material 1 and the mold material 11 is preferably 1000 min ⁻¹ or more. By setting the rotation speed within this range, the coating agent 4 can be spread over the entire substrate 1.
If the rotation speed of the base material 1 and the mold material 11 is too large, the coating agent 4 tends to be washed away by centrifugal force, and is preferably 3000 min− ¹ or less.

As shown in FIG. 6, the coating agent 4 is irradiated with ultraviolet rays (UV) through the substrate 1 to be cured. As a result, the cover layer 5 is formed on the surface of the recording layer 2. The coating agent 4 can be irradiated with ultraviolet rays through the mold material 11.
For ultraviolet irradiation, a high pressure mercury lamp, a metal halide lamp, or the like can be used.

As shown in FIGS. 7 and 8, a peeling gas such as air or nitrogen is sent between the cover layer 5 and the peelable coating layer 3 to peel them off.
Through the above steps, an optical information recording medium 10 having the recording layer 2 and the cover layer 5 formed on the surface of the base material 1 is obtained.
The mold material 11 is reusable, and a plurality of optical information recording media 10 can be produced using one mold material 11.

As shown in FIG. 9, the optical information recording medium 10 includes a base material 1, a recording layer 2 provided on the surface of the base material 1, and a light-transmitting cover layer 5 that covers the recording layer 2. The cover layer 5 is located on the surface of the optical information recording medium 10.
The optical information recording medium 10 can read data recorded on the recording layer 2 through the cover layer 5.
The optical information recording medium 10 is preferably used as an optical information recording medium (for example, a Blu-ray disc) for a blue laser having an oscillation wavelength of laser light of 370 to 430 nm.

According to the manufacturing method, the flat cover layer 5 along the surface of the mold material 11 is easily formed on the surface of the recording layer 2 by spreading the liquid coating agent 4 between the base material 1 and the mold material 11. Can do.
Further, since the operation is easy, there is no disadvantage in terms of manufacturing cost.
Further, by reusing the mold material 11, it is possible to reduce the manufacturing cost.

It is process drawing explaining an example of the manufacturing method of the optical information recording medium of this invention. It is process drawing following a previous figure. It is process drawing following a previous figure. It is process drawing following a previous figure. It is process drawing following a previous figure. It is process drawing following a previous figure. It is process drawing following a previous figure. It is process drawing following a previous figure. It is a schematic block diagram which shows an example of the optical information recording medium of this invention. It is a schematic block diagram which shows an example of the conventional optical information recording medium.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Base material, 2 ... Recording layer, 4 ... Coating agent, 5 ... Cover layer, 10 ... Optical information recording medium, 11 ... Mold material.

Claims (6)

An optical information recording medium comprising: a base material; a recording layer provided on one surface of the base material; and a light-transmitting cover layer covering the recording layer, wherein the recording layer can be read through the cover layer A method of manufacturing comprising:
The mold material is spread between the base material and the mold material by centrifugal force generated by rotating the substrate and the base material on which the recording layer is formed facing each other. A method for producing an optical information recording medium, comprising forming the cover layer along a surface on the surface of the recording layer, and then peeling the cover layer from the mold material.   The method for producing an optical information recording medium according to claim 1, wherein the mold material includes a mold material main body and a peelable coating layer provided on a surface thereof.   The method for producing an optical information recording medium according to claim 1, wherein the coating agent has a viscosity of 1500 to 3000 mPa · s (25 ° C.). The method for manufacturing an optical information recording medium according to any one of claims 1 to 3, wherein the number of rotations when rotating the base material and the mold material is 1000 to 3000 min- ¹ .   The method for manufacturing an optical information recording medium according to any one of claims 1 to 4, wherein the cover layer is peeled from the mold material by feeding a peeling gas between the cover layer and the mold material. The optical information recording medium obtained by the manufacturing method of the optical information recording medium of any one of Claims 1-5.

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