JP2003203400A - Spin coating method and optical disk - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve in-plane uniformity and to stabilize quality in mass production. <P>SOLUTION: A coating liquid is discharged from a nozzle 14 to a medium to be coated 2 rotated centering on a shaft center perpendicular to a coating surface, and a thin film is formed by solidifying the coating liquid discharged to the coating surface by centrifugal force acting the coating liquid on the coating surface. In such a case, the surface tension γ and viscosity η of the coating liquid are set within the range of 20 mN/s≤γ<30 mN/s, 0.50 MPa.s≤η<30 MPa.s, and 0.50≤γ/η. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a spin coating method and an optical disc.

[0002]

2. Description of the Related Art In recent years, for example, CD-ROM, CD-
Optical discs having names such as R and CD-RW are widely used. Particularly, in recent years, with the demand for larger capacity in the market, recently, DVD-ROM, DVD-R, D
Large capacity optical disks such as VD + R and DVD-RW are also popular. Such optical discs are widely used in the fields of information processing, image processing, audio, etc., and generally, recorded information is indicated by the intensity of reflected light of laser light emitted. It is a thing.

For example, in a read-only optical disc in which information is recorded by the unevenness of the disc surface, a reflective layer for reflecting laser light, a pit and a reflective layer provided on the substrate are provided on a transparent substrate having pits formed thereon. It has a protective layer for protecting it from external impacts.

A write-once / rewritable optical disc in which information is recorded by changing the properties of the recording layer is formed by laminating a recording layer, a reflective layer, a protective layer, etc. on a substrate on which guide grooves are formed. ing. An information rewritable optical disc such as a CD-RW has a dielectric layer sandwiching a recording layer.

As one of the methods for forming a thin film on a substrate, a coating medium is rotated around an axis perpendicular to the surface of the coating on which the thin film is formed, and a coating liquid is discharged from a nozzle onto the coating medium. There is a spin coating method in which the coating liquid is applied to the coating surface by a centrifugal force acting on the coating liquid on the coating surface.

[0006]

By the way, a substrate used for an optical disk may have a small affinity with a coating liquid used for forming a recording layer or a protective layer, and depending on spin coating conditions, The coating liquid may become a liquid droplet on the surface of the substrate. Since the substrate is rotated during spin coating, the coating liquid that has become a liquid ball does not adhere to the substrate and rolls toward the outer peripheral side of the substrate in the state of a liquid ball.

The liquid droplets that have rolled to the edge of the substrate may collect on the outer edge of the substrate, wrap around on the back surface, or may be shaken off without adhering to the substrate. Cannot be applied.

Therefore, the formed protective layer and recording layer are
Variations in film thickness and coating unevenness occur within a single film surface, and the uniformity of the thin film within the film surface (hereinafter referred to as in-plane uniformity) deteriorates.

In order to solve such a problem, for example, Japanese Patent Laid-Open Nos. 2000-215528 and 2000-
Various spin coating methods are introduced in JP-A-155994, JP-A-7-213989 and the like.

Japanese Unexamined Patent Publication No. 2000-215528 and Japanese Unexamined Patent Publication No. 2
In 000-155994, the rotation during coating is controlled to make the surface uniform. In addition, JP-A-7
Japanese Patent No. 213989 discloses that the nozzle height is adjusted so that the affinity with the substrate can be secured for a relatively high-viscosity coating liquid having a viscosity of 30 mPa · s or more.

However, with the above-described technique, it is difficult to secure a stable affinity between the substrate and the coating liquid during practical mass production, and a thin film having good in-plane uniformity is stable. Difficult to form.

It is an object of the present invention to obtain a spin coating method and an optical disk capable of improving in-plane uniformity and stabilizing quality during mass production.

[0013]

The invention according to claim 1 is
A coating liquid is discharged from a nozzle onto a coating medium that rotates about an axis perpendicular to the coating surface, and the coating liquid is applied to the coating surface by a centrifugal force that acts on the coating liquid on the coating surface. A coating step, and a thin film step of solidifying the coating liquid applied to the coating surface to form a thin film. The surface tension γ and the viscosity η of the coating liquid are 20 mN.
/ S ≦ γ <30 mN / s, 0.50 mPa · s ≦ η <3
It is set within the range of 0 mPa · s and 0.50 ≦ γ / η.

Therefore, by adjusting the surface tension γ, the viscosity η, and γ / η of the coating liquid, the contact angle between the coating liquid on the coating surface and the coating surface falls within the range that does not form a liquid ball on the coating surface. Maintained. This makes it possible to ensure a good affinity between the coating surface and the coating liquid when the coating medium is rotated.

According to a second aspect of the present invention, in the spin coating method according to the first aspect, the coating liquid is at least one of a cyanine dye, an azo dye, a phthalocyanine dye, and a naphthalocyanine dye. And an organic solvent that dissolves the dye.

Therefore, when the coating liquid in which at least one of the cyanine dye, the azo dye, the phthalocyanine dye, and the naphthalocyanine dye is dissolved in an organic solvent is used, the action of the invention of claim 1 It will be possible to obtain.

According to a third aspect of the present invention, in the spin coating method according to the first aspect, the coating liquid contains an ultraviolet curable resin.

Therefore, when the coating liquid containing the ultraviolet curable resin is used, it is possible to obtain the action of the invention described in claim 1.

According to a fourth aspect of the present invention, in the spin coating method according to the first, second or third aspect, the distance D between the tip of the nozzle and the coating surface and the discharge added to the coating liquid discharged from the nozzle. Pressure P is 1.0 mm ≤
D <5.0 mm, 0.1 kgf / cm ² ≦ P <1.5 kg
Set within the range of f / cm ² .

Therefore, the distance D between the tip of the nozzle and the coating surface, and the discharge pressure P applied to the coating liquid discharged from the nozzle.
By adjusting, it is possible to prevent the coating liquid discharged from the nozzle from splashing from the coating surface and adhering to the nozzle, and the coating liquid discharged from the nozzle can be favorably adhered to the coating surface.

According to a fifth aspect of the invention, in the spin coating method according to the fourth aspect, the inner diameter r of the nozzle is
Is set within the range of 0.20 mm ≦ r <2.00 mm.

Therefore, by adjusting the inner diameter r of the nozzle, it is possible to prevent the occurrence of coating unevenness due to the insufficient discharge amount, and the increase in manufacturing cost due to the excessive discharge amount. It will be possible.

The invention according to claim 6 is the same as claim 1, 2 or
In the spin coating method according to 3, 4, or 5, in the coating step, the tip of the nozzle is made to face the coating surface, and the coating liquid is discharged in the axial direction of the coating surface.

Therefore, since the tip of the nozzle faces the coating surface and the coating liquid is discharged in the axial direction of the coating surface, the coating liquid can be reliably discharged onto the coating surface.

The invention according to claim 7 is the invention as defined in claims 1, 2 and
In the spin coating method according to 3, 4, 5 or 6, the discharge time t of the coating liquid is 1.0 sec ≦ t <
Set within the range of 10 sec.

Therefore, the discharge amount can be adjusted by adjusting the discharge time, and the necessary and sufficient coating liquid can be applied.

The invention according to claim 8 is the invention according to claim 1,
In the spin coating method described in 3, 4, 5, 6 or 7, in the coating step, the rotation speed S of the coating medium is set within a range of 10 rpm ≦ S <1000 rpm.

Therefore, the coating liquid can be applied in a perfect circular shape centered on the axis.

The invention according to claim 9 is the invention according to claims 1, 2 and
In the spin coating method described in 3, 4, 5, 6 or 7, in the coating step, the rotation speed S of the coating medium is changed to a plurality within a range of 10 rpm ≦ S <1000 rpm.

Therefore, the application liquid can be applied in a perfect circular shape centered on the axis.

According to a tenth aspect of the present invention, in the spin coating method according to the eighth or ninth aspect, after the coating step, a rotational speed of the coating medium is accelerated to shake off the coating liquid from the coating medium. And the rotational speed S ′ of the coating medium in this remainder treatment step.
Is set within the range of 1000 rpm ≦ S ′ ≦ 8000 rpm.

Therefore, the excess coating liquid can be shaken off in the necessary minimum time without deteriorating the in-plane uniformity of the coating liquid applied on the coating surface.

The invention according to claim 11 is the spin coating method according to any one of claims 1 to 10, wherein the coating step and the residual treatment step are performed at a constant temperature T.
The temperature is kept at 15 ° C ≤
Set within the range of T <30 ° C.

Therefore, during mass production, it is possible to prevent the components contained in the coating liquid from changing over time due to evaporation / volatilization or the like.

An optical disk according to a twelfth aspect of the present invention comprises a transparent coated medium having a coated surface, a reflective layer laminated on the coated surface of the coated medium, and a protective layer laminated on the reflective layer. An optical disc comprising at least the protective layer formed by the spin coating method according to claim 1.

Therefore, by using the spin coating method according to any one of claims 1 to 11, it is possible to stably mass-produce optical disks having an in-plane uniform thin film.

An optical disk according to a thirteenth aspect of the present invention is a transparent coated medium having a coated surface, a recording layer laminated on the coated surface of the coated medium, a reflective layer laminated on the recording layer, and A protective layer laminated on the reflective layer,
At least one of the recording layer and the protective layer is formed by the spin coating method according to any one of claims 1 to 11.

Therefore, by using the spin coating method according to any one of claims 1 to 11, it is possible to stably mass-produce the optical disc having the in-plane uniform thin film.

[0039]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of the present invention will be described with reference to FIGS. The present embodiment shows an application example to an optical disc.

FIG. 1 is a sectional view showing the structure of an optical disc according to an embodiment of the present invention. The optical disc 1 includes a reproduction-only optical disc 1A (see FIG. 1A), an information-recordable optical disc 1B (see FIG. 1B), and a rewritable optical disc 1C (FIG. 1C). (See) etc.

As shown in FIG. 1A, the reproduction-only optical disc 1A has a substrate 2 as a disk-shaped transparent coated medium.
And a reflective layer 3 provided on one surface of the substrate 2 for reflecting laser light. On the substrate 2 used for the reproduction-only optical disc 1A, pits 4 are formed in advance on the side where the reflection layer 3 is formed. The reflective layer 3 is provided with a protective layer 5 for protecting the reflective layer 3 from external impact. The protective layer 5 may be provided with a printing layer 6 displaying a brand name or the like, if necessary. The protective layer 5 can be provided on the side of the substrate 2 on which laser light is incident (lower side in FIG. 1), if necessary.

As shown in FIG. 1B, the optical disc 1B on which information can be additionally written includes a substrate 2 and a reflective layer 3 in addition to a disk-shaped transparent substrate 2, a reflective layer 3, a protective layer 5 and the like. The recording layer 7 is provided between them. The substrate 2 of the optical disc 1B shown in FIG. 1 (b) is provided with a guide groove 4'instead of the pit 4 shown in FIG. 1 (a).

Information rewritable optical disc 1C
As shown in FIG. 1 (c), has a recording layer 7 formed of a material that undergoes a phase change to a crystalline / amorphous state upon irradiation with laser light. Dielectric layers 8 are provided on both sides of the recording layer 7 of the optical disc 1C. The substrate 2 of the optical disc 1C is provided with a guide groove 4'as in the optical disc 1B shown in FIG. 1 (b).

Substrate 2 of optical disc 1 (1A, 1B, 1C)
Is formed of a material such as plastic such as polycarbonate, polymethylmethacrylate, polystyrene resin, vinyl chloride resin, epoxy resin, or glass. In particular, polycarbonate is desirable as a material for forming the substrate 2 of the optical disc 1 in view of characteristics such as optical characteristics and temperature / humidity characteristics. The material forming the substrate 2 is not limited to the above materials.

The recording layer 7 is, for example, an azo dye, a cyanine dye, a phthalocyanine dye, a naphthalocyanine dye, a pyrylium dye, an azurenium dye, a squarylium dye, a metal complex salt dye such as Ni or Cr, and a naphthoquinone. Coating by dispersing organic dye materials such as anthraquinone-based dyes, indophenol-based dyes, indoaniline-based dyes, triphenylmethane-based dyes, triallylmethane-based dyes, aluminum-based / zinmonium-based dyes and nitrozo compounds in organic solvents It is formed by applying the liquid to the substrate 2 by a spin coating method described later. Particularly, a phthalocyanine compound having excellent light resistance is desirable as the organic dye material forming the recording layer 7. The film thickness of the recording layer 7 is usually set in the range of 300Å to 5000Å, preferably 700Å to 2000Å.

Examples of the organic solvent used in the coating liquid for forming the recording layer 7 include alcohol, cellosolve, carbon halide, ketone, ether and the like. The organic solvent used in the coating liquid may be one type or a mixed system of two or more types.

The recording layer 7 can also be formed of an inorganic material. For example, it is possible to use a phase change material that can change the atomic arrangement and record information. In this case, the recording layer 7 includes a phase change material layer and a heat insulating layer for holding heat of the phase change material.

As the phase change material, specifically, (A)-
It is an alloy represented by (B)-(C) -Ge-Te. Where (A) = Cu, Ag, Au, Sc, Y, Ti, Zr,
V, Nb, Cr, Mo, Mn, Fe, Ru, Co, R
h, Ni, Pd, Hf, Ta, W, Ir, Pt, Hg,
At least one element of B, C, N, P, O, S, Se, a lanthanide element, an actinide element, an alkaline earth metal element, an inert gas element and the like is represented. (B) is Ti, I
At least one of halogen elements such as halogen and alkali metal elements such as Na is shown. (C) is Sb, Sn, A
At least one element of s, Pb, Bi, Zn, Cd, Si, Al, Ga and In is shown.

In addition, for example, Tb and F of the above metal elements
It is also possible to use a metal material such as e and Co used for a magneto-optical material as the recording layer 7.

The reflective layer 3 is made of Au, Ag, Cu, Ni, A.
It is formed of a metal such as 1 or Pt or an alloy of these metals so that the film thickness is in the range of 300 Å or more and 2500 Å or less. Especially, in terms of cost and disk characteristics, A
g, Al, Ti, and Al are desirable as the material forming the reflective layer 3.

The protective layer 5 is formed by a cross-linking reaction of an ultraviolet curable resin and a cross-linkable monomer so that the film thickness is adjusted to 1 μm or more and 30 μm or less. The thickness of the protective layer 5 is preferably about 1.0 μm.

Examples of the UV curable resin include hydroxyethyl (meth) acrylate and hydroxypropyl.
(Meth) acrylate, hydroxybutyl (meth) acrylate, hydroxypentyl (meth) acrylate, phenoxyhydroxypropyl (meth) acrylate, chlorohydroxypropyl (meth) acrylate, diethylene glycol mono (meth) acrylate, triethylene glyco-
Mono (meth) acrylate, polyethylene glycol mono (meth) acrylate, dipropylene glycol mono
(Meth) acrylate, polypropylene glycol mono
(Meth) acrylate, glycerin mono (meth) acrylate, glycerin di (meth) acrylate, pentaerythritol (meth) acrylate, phenyl glycidyl ether (meth) acrylate, dipentaerythritol penta
There are acrylate resins such as (meth) acrylate and di (meth) acrylate of bisphenol A epoxy resin.

Examples of the crosslinkable monomer include trimethylolpropane tri (meth) acrylate, acrylated isocyanurate, 1.4 butanediol di (meth) acrylate, 1.6 hexanediol di (meth) acrylate and neopentylglycol. Examples include rudi (meth) acrylate, dicyclopentanedienyl di (meth) acrylate, pentaerythritol tetra (meth) acrylate and the like.

By the way, in order to form the protective layer 5,
A radical initiator that initiates a crosslinking reaction between an ultraviolet curable resin and a crosslinking monomer is required. Examples of the radical initiator include 1-hydroxycyclohexyl phenyl ketone, 2-hydroxy 2-methyl 1-phenylpropan 1-one, 2.2-diethoxyacetophenone, 4-
Phenoxy 2.2-acetophenone-based radical initiators such as 2-dichloroacetophenone, propiophenone-based radical initiators such as 2-hydroxy-2-methylpropiophenone, anthraquinone-based radical initiators such as 2-chloroanthraquinone, 2 There are thioxanthone-based radical initiators such as .4-diethylthioxanthone. The radical initiator usually has a composition ratio (weight ratio) of 1% to 1%.
0% is added. The radical initiator may be used alone or in combination of two or more.

In addition, the protective layer 5 contains a defoaming agent and a thickening agent such as silica. It should be noted that the defoaming agent and the thickener are not always added, but are added as necessary.

Next, the manufacturing process of the optical disc 1B will be described in the order of processes. The optical disc 1B is formed by injection molding the substrate 2 having the guide groove 4'using a stamper (not shown).

A recording layer is laminated on the formed substrate 2 by using a spin coating method. In this embodiment, a spin coater as shown in FIG. 2 is used for spin coating. The spin coater 10 is, as shown in FIG. 2, a spin coating medium on which a thin film is spin-coated.
It has a base portion 11 for supporting the coating surface 2a of the substrate 2 here in a horizontal state.

The base portion 11 is provided rotatably around the axis centering on the support shaft 12 arranged in the vertical direction. A spindle motor 13 that rotates the base unit 11 in the surface direction is connected to the base unit 11.

A nozzle 14 for discharging the coating liquid is positioned above the base 11. Inner diameter of nozzle 14
(r) is set within the range of the formula (1) shown below. 0.2 mm ≦ r <20 mm (1)

The nozzle 14 is supported by an arm 15 so that its tip faces the base 11. The arm 15 is rotatably provided around a support shaft provided on the opposite side of the nozzle 14. A motor (not shown) is connected to the arm 15, and the nozzle 14 is reciprocated in the radial direction of the substrate 14 by driving the motor. The rotation range of the arm 15 is set so that the nozzle 14 reciprocates within a range facing the coating surface 2a.

Since the rotation range of the arm 15 is set so as to reciprocate within the range in which the nozzle 14 faces the coating surface 2a, the coating liquid discharged from the nozzle 14 must be adhered to the coating surface 2a. You can This can prevent unnecessary consumption of the coating liquid and scattering of the coating liquid due to the unevenness of the end surface of the substrate 2. This makes it possible to obtain a uniform film thickness within the coating surface 2a and prevent the coating liquid from being applied to the non-application region.

Further, the arm 15 is provided with a nozzle so that the distance D between the tip of the nozzle 14 and the coating surface 2a of the substrate 2 set on the base 11 is within the range of the following formula (2). Support 14. 1.0mm ≦ D <5.0mm (2)

Although not shown in particular, the nozzle 14 is connected to a coating liquid supply pipe having one end connected to a coating liquid tank holding the coating liquid and the other end connected to the nozzle.

In the coating tank, the coating liquid whose surface tension γ, viscosity η and γ / η were adjusted to fall within the ranges of the following formulas (3), (4) and (5): It is filled. 20 mN / s ≦ γ <30 mN / s (3) 0.50 mPa · s ≦ η <30 mPa · s (4) 0.50 ≦ γ / η (5)

In addition, although not particularly shown, the spin coater 10 has a pressurizing device for applying pressure to the coating liquid in the nozzle 14. By applying pressure to the coating liquid in the nozzle 14 with a pressure device, the nozzle 14
The coating liquid is discharged from the. In the present embodiment, the application liquid in the nozzle 14 by the pressurizing device will be described below.
The pressure P adjusted within the range of the formula (6) is applied. 0.1 kgf / cm ² ≦ P <1.5 kgf / cm ² (6)

The discharge amount of the coating liquid discharged from the nozzle 14 is controlled by the discharge amount adjusting valve 1 provided above the nozzle 14.
6 can be adjusted. by this,
A predetermined amount of coating liquid can be discharged from the nozzle 14 onto the coating surface 2a of the substrate 2.

Around the base 11 and the spindle motor 13, a liquid splash prevention hood 17 is provided which covers the sides and above the base 11 and the spindle motor 13. As a result, it is possible to prevent the coating liquid shaken off from the outer peripheral edge portion of the substrate 2 from scattering to the periphery in the remainder processing step to be described later. It is open so that the coating liquid can be discharged.

The spin coater 10 of the present embodiment is installed and used in a temperature / humidity control booth (not shown).
The temperature T in the temperature / humidity control booth is kept constant so as to fall within the range of the following expression (7). 15 ℃ ≦ T <30 ℃ ・ ・ ・ (7)

In forming the recording film 7, first, the coating liquid is applied in the coating process, then the excess coating liquid is removed from the coating surface 2a in the residual treatment process, and then the coating liquid applied in the thin film process. Is solidified to form a thin film.

In the coating process, the spin coater 10
The substrate 2 is set on the base 11. At this time, the coating surface 2 a having the guide groove 4 ′ is set so as to face the tip of the nozzle 14. In this state, the spindle motor 13 is driven to rotate the base 11. In the present embodiment, the spindle motor 13 is rotated so that the rotation speed S of the substrate 2 satisfies the range of the formula (8) shown below. 10 rpm ≦ S <1000 rpm (8)

External pressure is applied to the inside of the nozzle 14 by a pressurizing device while the base 11 is rotating. The coating liquid to which the external pressure is applied is discharged toward the substrate 2.

When the viscosity η of the coating liquid is excessively high at the time of discharging, the liquid resistance increases, so that the pressure is not properly transmitted and a pressure loss occurs. In such a case, the pressure is not satisfactorily transmitted to the coating liquid in the nozzle 14 at the time of ejection, and ejection failure occurs.

In this embodiment, the viscosity η of the coating liquid is (4)
Since the pressure is set within the range of the formula, the pressure is satisfactorily transmitted to the coating liquid in the nozzle, and the good ejection can be performed.

When discharging, the inner diameter r of the nozzle 14
If the thickness is too small, the discharge amount in a unit time decreases, so that it is not possible to supply a sufficient amount of the coating liquid to the substrate surface, which may cause uneven coating within the surface. . On the contrary, if the inner diameter r of the nozzle 14 is too large, the coating liquid may be excessively supplied, which may increase the manufacturing cost.

In this embodiment, the inner diameter r of the nozzle 14 is
However, since it is set within the range of the formula (2), it is possible to discharge the desired discharge amount without difficulty, and it is possible to prevent the above-mentioned problems from occurring.

In addition, if the distance D between the nozzle 14 and the surface of the substrate 2 is too short, the coating liquid bounces off the irregularities or the like formed on the coating surface 2a by the guide groove 4 ', and the nozzle 14 is soiled by the bounced coating liquid. It may happen. In such a case, if the coating is continuously performed, the nozzle 14 may be clogged with the coating liquid that has rebounded, which may cause a coating defect. On the contrary, if the distance D is too large, the discharge pressure from the nozzle 14 is not sufficiently transmitted to the coating surface 2a. If the discharge pressure is insufficient, the coating liquid will be
Liquid droplets tend to be formed with a. In order to prevent such a problem with the same distance D, the discharge amount must be increased, and the coating liquid will be consumed excessively. Therefore, the manufacturing cost is increased.

In the present embodiment, since the distance D between the nozzle 14 and the surface of the substrate 2 is set within the range shown in the equation (1), the coating liquid bounces off the substrate 2 and the nozzle 14 is soiled or discharged. It is possible to prevent problems such as insufficient liquid pressure and liquid droplets.

Whether or not the discharged liquid that reaches the coating surface 2a becomes a liquid ball depends on the relationship between the affinity between the substrate 2 and the coating liquid and the surface tension γ of the coating liquid.

Here, the coating liquid is dripped onto the coating surface 2a when the substrate 2 is in a stationary state, and the liquid diameter when the coating liquid adheres to the coating surface 2a is measured with respect to the liquid diameter when dropped (when dropped). Thus, the relationship between the affinity between the substrate 2 and the coating liquid and the surface tension γ of the coating liquid was verified.

As a result, it was found that the spread of the coating liquid largely depends on the surface tension of the coating liquid.

Further, in the coating process, since the substrate 2 onto which the coating liquid is dropped is rotated, the coating liquid contacting the substrate 2 is subjected to a centrifugal force from the inner peripheral side to the outer peripheral side of the substrate 2. Works. Under the condition of centrifugal force,
It was found that the higher the surface tension γ is, the more easily the coating liquid tends to be a liquid droplet.

Therefore, in the coating step, it is necessary to secure the affinity in consideration of the centrifugal force due to the rotation of the substrate 2.

Now, the relationship between the surface tension γ and the viscosity η when the centrifugal force due to the rotation acts on the substrate 2 will be described. According to experiments, under a certain rotation speed setting, the relationship between the surface tension γ and the viscosity η tends to increase as γ / η increases, and decrease as γ / η decreases. I knew that. That is, the surface tension γ
The larger the value is, and the smaller the viscosity η is, the more the affinity is secured.

On the other hand, it was found that the affinity tends to decrease when the surface tension γ alone is excessively increased or the viscosity η alone is excessively decreased.

As a result, when γ / η, which represents the relationship between the surface tension γ and the viscosity η, is set within the range shown in the equation (5), a good affinity is obtained between the substrate 2 and the coating liquid. It turned out that sex is obtained.

By the way, if the rotation speed S of the substrate 2 at the time of applying the coating liquid is excessively low, the coating liquid will not spread evenly around the support shaft 12 and will spread partially unevenly. Sometimes. Further, if the rotation speed S of the substrate at the time of applying the coating liquid is excessively low, the yield will be reduced. On the other hand, when the rotation speed S of the substrate 2 at the time of applying the coating liquid is excessively high, the centrifugal force acting on the coating liquid has a stronger influence than the affinity between the dropped coating liquid and the substrate 2. Then
Liquid drops are likely to occur.

In the present embodiment, the number of revolutions is set within the range of the formula (8), so that the generation of liquid beads is suppressed and the coating liquid is spread in a perfect circle shape around the support shaft 12. Can be made.

In this embodiment, the surface tension γ and the viscosity η of the coating liquid are set within the ranges of the formulas (3), (4) and (5) so that the liquid is discharged from the nozzle 14 and laminated. The contact angle between the coating liquid adhering to the surface and the solvent to be coated is kept to such an extent that the dropped coating liquid does not form a liquid ball on the coating surface 2a. As a result, the coating liquid flows from the inner peripheral side to the outer peripheral side of the substrate 2 by the centrifugal force while attracting each other from the position in contact with the coating surface 2a due to the affinity for each other, so that the coating liquid flows to the position where the coating liquid has passed. Film is formed.

Further, in the present embodiment, since the moving range of the nozzle 14 at the discharge position is positioned so as to face the coating surface 2a of the substrate 2, the discharged coating liquid is
It contacts the coating surface 2a within the coating range.

In this embodiment, the rotation speed S of the substrate 2 during the coating process is constant, but the present invention is not limited to this, and the rotation speed of the substrate 2 during the coating process is constant in the present invention. Alternatively, it may be changed continuously or stepwise within the above range.

By the way, if the discharge time t from the start of discharge to the end of discharge is short, it is difficult for the coating liquid to uniformly flow in the circumference, and coating spots are likely to occur. On the other hand, when the ejection time t is excessively long, the coating liquid is excessively dropped, so that the cost performance is lowered.

On the other hand, in this embodiment, the external pressure is applied to the nozzle 14 so that the ejection time t from the start of ejection to the end of ejection is within the range shown in the equation (8).
The coating liquid can be uniformly applied to the coating surface 2a without running out of the coating liquid or consuming the coating liquid excessively.

Next, as a remainder processing step, when the ejection time t has elapsed from the start of dropping, the rotation speed of the spindle motor 13 is accelerated and the rotation speed S ′ of the substrate 2 is shown below (9).
Accelerate to within the formula. 1000 rpm ≦ S ′ <8000 rpm (9)

As a result, the coating liquid that has flowed to the outer peripheral edge of the substrate 2 is discharged to the outside while being shaken off from the outer peripheral edge of the substrate 2.

Here, in the remainder processing step, if the rotation speed is excessively slow in the same rotation time, the film thickness becomes thick. If you try to shake off at the same rotation speed, it will take a long time to shake off the excess coating liquid. Further, if the number of revolutions is excessively accelerated in the excess treatment step, an excessive centrifugal force acts on the coating liquid, and it becomes difficult to obtain a uniform film thickness within the surface.

In the present embodiment, the number of revolutions S'after ejection is
By setting within the range of the expression (9), a film having a desired film thickness can be efficiently formed.

Here, since the spin coater 10 was installed in an environment set to a constant temperature T to form a thin film,
It is possible to prevent a change over time in the coating liquid that would cause the organic solvent to evaporate and the dye concentration in the coating liquid to change. This makes it possible to stably form a thin film having good in-plane uniformity over a long period of time even when a coating liquid that easily evaporates, such as an organic solvent that develops a dye, is used.

The recording layer 7 is formed by drying and solidifying the coating film formed as described above to form a thin film.

For example, in order to remove the residual solvent, the substrate 2 spin-coated with the organic dye may be annealed at a high temperature. Annealing temperature is usually 80
It is carried out at up to 110 ° C, preferably around 100 ° C.
The annealing time is usually about 15 to 30 minutes.

When the recording layer 7 is formed of the above-mentioned inorganic metal material, a vacuum deposition method, a sputtering method,
It can be formed by an ion plating method. When the recording layer is formed of an inorganic metal material, it is particularly preferable to use the sputtering method.
Descriptions of the vacuum vapor deposition method, the sputtering method, the ion plating method, and the like are omitted.

Next, the reflective layer 3 is formed on the substrate 2 on which the recording layer 7 is formed. The reflective layer 3 is made of Au, Ag, C
It is formed of a metal such as u, Ni, Al, or Pt or an alloy of these metals so that the film thickness is in the range of 300 Å or more and 2500 Å or less. In particular, Ag, Al, Ti, and Al are preferable as the material for forming the reflective layer 3 in terms of cost, disk characteristics, and the like. The reflective layer can be formed by a vacuum vapor deposition method, a sputtering method, or an ion plating method. In this embodiment mode, the reflective layer is formed by a sputtering method.

Then, similarly to the recording layer 7, the reflective layer 3
The protective layer 5 is laminated on. Like the recording layer 7, the protective layer 5 is formed by undergoing a coating step, a residual treatment step, and a thin film forming step. Thereby, the in-plane uniform protective layer 5 can be formed.

Next, the protective layer 5 is formed on the substrate on which the reflective layer 3 is formed. The protective layer 5, like the recording layer 7,
The reflective layer 3 is laminated and formed through a coating process, a remainder processing process, and a thin film forming process. Protective layer 5
The coating liquid that forms the film also has surface tension γ, viscosity η and γ / η.
Is set within the range of the expressions (3), (4), and (5).
Also, various conditions in the spin coater are set to the same conditions as the settings when forming the recording layer 7. As a result, the protective layer 5 can be uniformly formed to have a desired film thickness.

Here, since the ultraviolet curable resin is used for the protective layer 5, there is a concern that the optical disc 1 may be warped due to contraction during curing of the protective layer 5, but in the present embodiment. Since the thickness of the protective layer 5 can be controlled within the range of 1 μm or more and 30 μm or less (about 1.0 μm in the present embodiment) capable of suppressing the occurrence of warpage, the occurrence of warpage is prevented. be able to.

In the present embodiment, the protective layer 5 is formed by using the spin coating method, but the present invention is not limited to this. For example, the protective layer 5 may be formed by screen printing or the like. Good. Alternatively, the print layer 6 may be provided with the function as the protective layer 5 without providing the protective layer 5.

The printing layer 6 of the present embodiment is formed by screen printing so that the film thickness is within the range of 5 to 20 μm. The thickness of the printed layer 6 is particularly preferably 8 to 12 μm. The printed layer 6 was formed using an ultraviolet curable ink containing a mixture of urethane acrylate, a polymerizable monomer, a pigment and a photopolymerization initiator (initiator). The material contained in the ink is not limited to this, and for example, a filler (viscosity adjusting agent), an antioxidant, etc. may be added if necessary.

The printing layer 6 is not limited to the screen printing method, and various printing methods such as a gravure printing method and an offset printing method can be used. The screen printing method, the gravure printing method, and the offset printing method are known techniques, and therefore description thereof will be omitted.

After forming the protective layer 5, the recording layer 7 may be initialized if necessary. The initialization is a step of increasing the reflectance by crystallizing the recording layer 7 made of an inorganic metal material having a low reflectance in an amorphal state immediately after sputtering. In the initializing step, the protective layer may be optionally arranged afterwards, but preferably immediately after the protective layer 5 is formed.

In addition, the optical disc 1 which has undergone the above-mentioned steps
On the other hand, a step of forming a protective layer (not shown) for protecting the substrate surface may be provided. Here, the substrate surface means a surface on which recording and reproducing light enters when the optical disc is completed. By forming a protective layer (not shown) on the surface of the substrate, the surface of the substrate can be protected from an external impact, and stable recording and reproducing states can be maintained for a long period of time.

The protective layer for protecting the surface of the substrate can be formed in the same manner as the above-mentioned protective layer 5. The protective layer for protecting the substrate surface can be arranged at any position after the substrate 2 is molded.

Although the optical disc 1 having the single-sided single layer structure has been described in the present embodiment, the present invention is not limited to this, and a single-sided double-layered structure, a double-sided single-layered structure, or a double-sided double-layered structure such as a DVD is used. It may be applied to the optical discs that it has.

For example, in the case of a bonded type optical disk such as a DVD, the process of bonding the substrates on which the protective layers are formed as described above is performed.

The substrate supplied from the protective layer forming step is bonded to another transparent substrate. As the adhesive, a known ultraviolet curing adhesive or a cationic ultraviolet curing adhesive is used.
After the substrate having the protective layer coated with the adhesive is placed on another transparent substrate, the transparent substrate on which the reflective layer is not formed is irradiated with ultraviolet rays to be cured and bonded.

[0114]

EXAMPLES Next, examples of the above-described embodiment will be described. Here, Examples 1-3 and Comparative Examples 1-2
The appearance of each type of optical disc was evaluated using five types of optical discs represented by. The three types of optical discs shown in Examples 1 to 3 satisfy the numerical range of the present embodiment, and the two types of optical discs shown in Comparative Examples 1 to 2 are formed so as to deviate from the numerical range of the present embodiment. (Table 1).

Two kinds of CD-R and DVD + R were prepared by the method of the present invention. In order to confirm the in-plane uniformity, the presence or absence of coating unevenness was visually confirmed.

First, the first embodiment will be described. The optical disc of Example 1 shows an example of application to a CD-R (see FIG. 1B). In addition, in Example 1, the recording layer and the protective layer,
It was formed by the spin coating method using the spin coater 10 described above.

When forming the recording layer, the distance D between the nozzle 14 and the coating surface 2a of the spin coater 10, the inner diameter r of the nozzle, the rotation speed S at the time of coating, the discharge pressure P from the nozzle 14 and the discharge time t are: , Is set as follows. Distance D = 2.0 mm Inner diameter of nozzle r = 0.61 mm Rotation speed during coating S = 250 rpm Discharge pressure P = 0.8 kgf / cm ² Discharge time t = 10 sec

The spin coater 10 has a constant temperature of 2
It is installed in a temperature / humidity control booth set at 5 ° C.

In Example 1, the diameter was 120 mm and the thickness was 1.
A transparent substrate 2 formed in a disc shape by 2 mm of polycarbonate was used as a coating medium. On one surface side of the substrate 2 to be the coated surface 2a, guide grooves 4'set at a pitch of 1.6 μm are formed.

The coating liquid applied to the coating surface 2a of the substrate 2 is
A coating solution prepared by dissolving a cyanine dye in fluorine alcohol was used. Surface tension γ, viscosity η, and surface tension γ of coating liquid
And the viscosity η are set as follows. Surface tension γ = 24.5 mN / s Viscosity η = 15.7 mPa · s γ / η = 1.6

In the coating process, the discharge of the coating liquid is started from the position radially spaced 40 mm from the center of the substrate 2 and the nozzle 14 is moved to the innermost peripheral side of the coating range. 40m in the radial direction from the center of the
The nozzle 14 was reciprocated so as to return to the position separated by m. At this time, the rotation speed S in the coating step is constant.

In the remainder processing step, the rotation speed of the spindle motor 13 was accelerated to 6000 rpm and the excess coating liquid was shaken off.

After applying the coating liquid for the recording layer 7 to the substrate 2, the substrate 2 was annealed at 100 ° C. for 20 minutes.

After that, the reflective layer 3 was formed by Ag in a thickness of about 1000 Å using a sputtering apparatus. Since the sputtering device is a known technique, its illustration and description are omitted.

Then, the protective layer 5 is formed on the reflective layer 3 by 5 times.
The layers were laminated so as to have a thickness of μm. When forming the protective layer 5, the distance D between the nozzle 14 and the coating surface 2a in the spin coater 10, the inner diameter r of the nozzle 14, the rotation speed S at the time of ejection, the ejection pressure P from the nozzle 14, the ejection time t.
Is set as follows. Distance D = 3.0 mm Inner diameter of nozzle r = 1.94 mm Rotation speed S = 250 rpm Discharge pressure P = 1.0 kgf / cm ² Discharge time t = 10 sec

As the coating liquid applied to the reflection layer 5, the surface tension γ, the viscosity η, and the relationship between the surface tension γ and the viscosity η were set as follows. SD1700 manufactured by DIC was used as the coating liquid. Surface tension γ = 28.0 mN / s Viscosity η = 28.0 mPa · s γ / η = 1.0

In the coating process, the discharge of the coating liquid is started from the position radially separated from the center of the substrate 2 by 30 mm, and the nozzle 14 is moved to the innermost peripheral side of the coating range. 30m in the radial direction from the center of the
The nozzle 14 was reciprocated so as to return to the position separated by m. At this time, the rotation speed S in the coating step is constant.

In the remainder processing step, the rotation speed of the spindle motor 13 was accelerated to 6000 rpm and the excess coating liquid was shaken off.

CD-R was produced as described above.

Next, a second embodiment will be described. The optical disc 1 of the second embodiment shows an application example to a CD-R (see FIG. 1B). In Example 1, the recording layer 7 and the protective layer 5 were formed by the spin coating method using the spin coater 10 described above.

When forming the recording layer, the distance D between the nozzle 14 of the spin coater 10 and the coating surface 2a, the inner diameter r of the nozzle, the rotation speed S during coating, the discharge pressure P from the nozzle 14 and the discharge time t are: , Is set as follows. Distance D = 2.0 mm Inner diameter of nozzle r = 0.61 mm Rotation speed during coating S = 250 rpm Discharge pressure P = 0.5 kgf / cm ² Discharge time t = 10 sec

Also, in the second embodiment, the same substrate 2a as in the first embodiment is used.

The coating liquid applied to the coating surface 2a of the substrate 2 is
A coating solution in which a phthalocyanine dye was dissolved in THF / 1M2B / MCH was used. The surface tension γ and the viscosity η of the coating liquid and the relationship between the surface tension γ and the viscosity η are set as follows. Surface tension γ = 23.8 mN / s Viscosity η = 0.7 mPa · s γ / η = 32.6

In the second embodiment, in the same manner as in the first embodiment, after performing the coating step, the residual treatment step and the annealing treatment,
Approximately 1000 reflection layer 3 was formed by Ag using a sputtering device.
It was formed to have a film thickness of Å.

Then, the protective layer 5 is formed on the reflection layer 3 by 5 times.
The layers were laminated so as to have a thickness of μm. When forming the protective layer 5, the distance D between the nozzle 14 and the coating surface 2a in the spin coater 10, the inner diameter r of the nozzle 14, the rotation speed S at the time of ejection, the ejection pressure P from the nozzle 14, the ejection time t.
Is set as follows. Distance D = 3.0 mm Inner diameter of nozzle r = 1.94 mm Rotation speed S = 250 rpm Discharge pressure P = 1.0 kgf / cm ² Discharge time t = 10 sec

As the coating liquid for coating the reflective layer 5, SD17 manufactured by DIC was used as the coating liquid in which the surface tension γ, the viscosity η, and the relationship between the surface tension γ and the viscosity η were set as follows. Surface tension γ = 28.0 mN / s Viscosity η = 27.0 mPa · s γ / η = 1.0

In the coating step, the discharge of the coating liquid is started from the position radially separated from the center of the substrate 2 by 30 mm, and the nozzle 14 is moved to the innermost peripheral side of the coating range. 30m in the radial direction from the center of the
The nozzle 14 was reciprocated so as to return to the position separated by m. At this time, the rotation speed S in the coating step is constant.

In the remainder processing step, the rotation speed S ′ of the spindle motor 13 was accelerated to 6000 rpm and the excess coating liquid was shaken off.

As the coating liquid applied to the reflective layer 3, SD1700 manufactured by DIC was used as a coating liquid in which the surface tension γ, the viscosity η, and the relationship between the surface tension γ and the viscosity η were set as follows. Surface tension γ = 28.0 mN / s Viscosity η = 27.0 mPa · s γ / η = 1.0

CD-R was prepared as described above.

Next, a third embodiment will be described. The optical disc of the third embodiment shows an application example to a DVD + R (not shown). The DVD + R has a structure in which the above-mentioned two optical disks are bonded together. In Example 3, the recording layer 7, the protective layer 5, and the adhesive layer (not shown) were formed by the spin coating method using the spin coater 10 described above.

When forming the recording layer, the distance D between the nozzle 14 of the spin coater 10 and the coating surface 2a, the inner diameter r of the nozzle, the rotation speed S during coating, the discharge pressure P from the nozzle 14 and the discharge time t are: , Is set as follows. Distance D = 2.0 mm Inner diameter of nozzle r = 0.72 mm Rotation speed during coating S = 250 rpm Discharge pressure P = 0.8 kgf / cm ² Discharge time t = 10 sec

The spin coater 10 has a constant temperature of 2
It is installed in a temperature / humidity control booth set at 5 ° C.

In Example 3, the transparent substrate 2 formed of the same polycarbonate as in Example 1 and having a disk shape was used as a coating medium. On one surface side of the substrate to be the coated surface 2a, guide grooves 4'set at a pitch of 0.74 μm are formed.

The coating liquid applied to the coating surface 2a of the substrate 2 is
A coating solution prepared by dissolving a cyanine dye in fluorine alcohol was used. Surface tension γ, viscosity η, and surface tension γ of coating liquid
And the viscosity η are set as follows. Surface tension γ = 23.8 mN / s Viscosity η = 27.8 mPa · s γ / η = 0.9

The coating step, the remainder treatment step and the annealing treatment were performed in the same manner as in Example 1.

After that, the reflection layer 3 made of Ag was formed in a thickness of about 1500 Å by using a sputtering apparatus.

Then, the protective layer 5 is formed on the reflective layer 3 by 5 times.
The layers were laminated so as to have a thickness of μm. When forming the protective layer 5, the distance D between the nozzle 14 and the coating surface 2a in the spin coater 10, the inner diameter r of the nozzle 14, the rotation speed S at the time of ejection, the ejection pressure P from the nozzle 14, the ejection time t.
Is set as follows. Distance D = 3.0 mm Inner diameter of nozzle r = 1.94 mm Rotation speed S = 250 rpm Discharge pressure P = 1.0 kgf / cm ² Discharge time t = 10 sec

The same coating liquid as in Example 1 was used as the coating liquid for coating the reflective layer 3.

The coating process and the residual treatment process were performed in the same manner as in Example 1.

Subsequently, an adhesive layer (not shown) was laminated on the protective layer 5. The adhesion layer was formed in the same manner as the formation of the protective layer 5 by using the spin coater 10 having the same setting as the formation of the protective layer 5.

As a coating liquid for coating the protective layer 5, an adhesive manufactured by Nippon Kayaku Co., Ltd. was used. The surface tension γ and the viscosity η of the coating liquid and the relationship between the surface tension γ and the viscosity η are set as follows. Surface tension γ = 27.0 mN / s Viscosity η = 28.0 mPa · s γ / η = 1.0

After applying the adhesive layer, it was irradiated with ultraviolet rays, and another substrate 2 was bonded thereon.

The DVD + R was manufactured as described above.

Next, Comparative Example 1 will be described. When forming a comparative layer (not shown) in Comparative Example 1, the distance D between the nozzle 14 and the coating surface 2a of the spin coater 10, the inner diameter r of the nozzle, the rotational speed S at the time of coating, the nozzle 14
The discharge pressure P and the discharge time t from are set as follows. Distance D = 1.5 mm Nozzle inner diameter r = 0.61 mm Rotation speed during coating S = 250 rpm Discharge pressure P = 0.8 kgf / cm ² Discharge time t = 10 sec

In Comparative Example 1, the same substrate 2 as in Example 1 was used as the coating medium.

The coating liquid applied to the coating surface 2a of the substrate 2 is
A commercially available ink having a surface tension γ, a viscosity η, and a relationship between the surface tension γ and the viscosity η set as follows was used. Surface tension γ = 47.0 mN / s Viscosity η = 2.2 mPa · s γ / η = 21.3

The coating process and the residual treatment process were performed in the same manner as in Example 1.

Next, Comparative Example 2 will be described. In Comparative Example 2, the same substrate 2 as in Example 1 was used. Substrate 2 has
Information pits having a pitch of 0.74 μm are formed.

On this substrate 2, a reflection layer 3 made of Al is formed.
The film thickness was 000Å and the film was formed by the sputtering method.

Subsequently, a protective layer 5 as a comparative layer was laminated on the reflective layer 3 so as to have a film thickness of 5 μm. When forming the protective layer 5, the distance D between the nozzle 14 and the coating surface 2a in the spin coater 10, the inner diameter r of the nozzle, the rotation speed S at the time of coating, the discharge pressure P from the nozzle 14, and the discharge time t are as follows. Is set like. Distance D = 3.0 mm Inner diameter of nozzle r = 1.94 mm Rotational speed during coating S = 200 rpm Discharge pressure P = 1.0 kgf / cm ² Discharge time t = 10 sec

During the coating process, 3 from the center of the substrate 2
The coating liquid was applied in the range of 0 mm from the position of 0 mm to the outer peripheral side in the range of 30 mm in the same manner as in Example 1, and the rotation speed S ′ was accelerated to 3000 rpm in the remainder treatment step.

The coating liquid applied to the reflective layer 3 was a commercially available ultraviolet curing agent having the surface tension γ, the viscosity η, and the relationship between the surface tension γ and the viscosity η set as follows. Surface tension γ = 51.0 mN / s Viscosity η = 170 mPa · s γ / η = 0.30

The coating unevenness of the recording layer 7 and the protective layer 5 of the optical disc 1 shown in the above Examples 1 to 3 and Comparative Examples 1 and 2 was visually evaluated. As a result, in the optical disc 1 shown in Examples 1 to 3, good in-plane uniformity was obtained in all of the recording layer 7, the protective layer 5, and the adhesive layer.

On the other hand, in the optical disk of Comparative Example 1, the discharged coating liquid became liquid drops on the coating surface 2a, and it was confirmed that coating unevenness was generated in the formed coating. In Comparative Example 2, the ejection of the coating liquid from the nozzle 14 becomes unstable, and the coating liquid does not have a perfect circular shape. In addition, the discharged coating liquid became liquid drops on the surface of the coating film, and it was confirmed that coating unevenness was generated in the formed coating film.

[0166]

According to the first aspect of the invention, the coating liquid is discharged from the nozzle onto the coating medium rotated about the axis perpendicular to the coating surface, and the coating liquid on the coating surface is discharged. A surface tension of the coating solution, including a coating step of coating the coating solution on the coating surface by an acting centrifugal force, and a thin film step of solidifying the coating solution coated on the coating surface to form a thin film. γ and viscosity η are 20 mN / s ≦ γ
<30 mN / s, 0.50 mPa · s ≦ η <30 mPa
・ By setting s, within the range of 0.50 ≤ γ / η, the contact angle of the coating liquid on the coating surface with respect to the coating surface is maintained within the range where liquid droplets do not form on the coating surface, and the coating medium Since it is possible to secure a good affinity between the coating surface and the coating liquid when is rotated, it is possible to improve the in-plane uniformity and stabilize the quality during mass production. .

According to the invention described in claim 2, in the spin coating method according to claim 1, at least one dye selected from the group consisting of a cyanine dye, an azo dye, a phthalocyanine dye and a naphthalocyanine dye, and the dye. When the coating solution containing the organic solvent to be dissolved is used, the effect of the invention according to claim 1 can be obtained.

According to the invention of claim 3, the effect of the invention of claim 1 can be obtained when the spin coating method of claim 1 uses a coating liquid containing an ultraviolet curable resin. .

According to a fourth aspect of the present invention, in the spin coating method according to the first, second or third aspect, the distance D between the tip of the nozzle and the coating surface and the discharge added to the coating liquid discharged from the nozzle. Pressure P is 1.0 mm ≤
D <5.0 mm, 0.1 kgf / cm ² ≦ P <1.5 kg
By setting it within the range of f / cm ² , it is possible to prevent the coating liquid discharged from the nozzle from bouncing from the coating surface and adhering to the nozzle, and to make the coating liquid discharged from the nozzle adhere well to the coating surface. As a result, the in-plane uniformity can be improved and the quality can be stabilized during mass production.

According to a fifth aspect of the present invention, in the spin coating method according to the fourth aspect, the inner diameter r of the nozzle is
Is set within the range of 0.20 mm ≦ r <2.00 mm, the coating amount may be insufficient due to insufficient discharge amount, or the discharge amount may become excessive and the manufacturing cost may increase. Since it is possible to prevent the above, it is possible to improve the in-plane uniformity and suppress an increase in manufacturing cost.

According to the invention of claim 6, claim 1,
In the spin coating method according to 2, 3, 4 or 5, coating is performed by causing the tip of the nozzle to face the coating surface and discharging the coating liquid in the axial direction of the coating surface in the coating step. Since the liquid can be reliably discharged onto the coating surface, it is possible to prevent the coating liquid from being excessively consumed.

According to the invention of claim 7, claim 1,
In the spin coating method described in 2, 3, 4, 5 or 6, the discharge time t of the coating liquid is 1.0 sec ≦
By setting it within the range of t <10 sec, the discharge amount can be adjusted by adjusting the discharge time, and the necessary and sufficient coating liquid can be applied.

The invention according to claim 8 is the same as claim 1, 2 or
In the spin coating method according to 3, 4, 5, 6 or 7, in the coating step, the rotation speed S of the coating medium is set within a range of 10 rpm ≤ S <1000 rpm, so that the coating liquid is centered on the axis. Since it can be applied in a perfect circular shape with the center, the application liquid can be applied evenly on the coating surface.

According to the invention of claim 9, claim 1,
In the spin coating method according to 2, 3, 4, 5, 6 or 7, in the coating step, the coating liquid is changed by changing the rotation speed S of the coating medium to a plurality within a range of 10 rpm ≦ S <1000 rpm. Can be applied in a perfect circular shape centered on the axis, so that the coating liquid can be applied evenly on the coating surface.

According to the invention of claim 10, claim 8 is provided.
The spin coating method according to claim 9, further comprising a residual treatment step of accelerating the rotation speed of the coating medium to shake off the coating liquid from the coating medium after the coating step, the rotational speed of the coating medium in the residual treatment step. By setting S ′ within the range of 1000 rpm ≦ S ′ ≦ 8000 rpm, the excess coating liquid is shaken off in the necessary minimum time without deteriorating the in-plane uniformity of the coating liquid applied on the coating surface. Therefore, the production efficiency can be improved.

According to the invention of claim 11, claim 1
11. In the spin coating method according to any one of 1 to 10, the coating step and the residual treatment step are performed in an environment kept at a constant temperature T, and the constant temperature T is set to 1
By setting in the range of 5 ° C. ≦ T <30 ° C., it is possible to prevent the components contained in the coating liquid from changing with time due to evaporation / volatilization or the like during mass production. It is possible to stabilize the quality.

According to the optical disk of the twelfth aspect, a transparent coated medium having a coated surface, a reflective layer laminated on the coated surface of the coated medium, and a protective layer laminated on the reflective layer. , And at least the protective layer is formed by the spin coating method according to any one of claims 1 to 11, thereby stably mass-producing an optical disk having a thin film having good in-plane uniformity. You can

[0178] An optical disc according to a thirteenth aspect of the present invention is a transparent coated medium having a coated surface, a recording layer laminated on the coated surface of the coated medium, a reflective layer laminated on the recording layer, and A protective layer laminated on the reflective layer,
Since at least one of the recording layer and the protective layer is formed by the spin coating method according to any one of claims 1 to 11, optical disks having an in-plane uniform thin film can be stably mass-produced.

[Brief description of drawings]

FIG. 1 is a sectional view showing a structure of an optical disc according to an embodiment of the present invention.

FIG. 2 is a schematic view showing a spin coater.

FIG. 3 is a schematic diagram showing a part thereof.

[Explanation of symbols]

1 optical disc 2 coating media 2a coating surface 3 reflective layer 5 protective layer 7 Recording layer 14 nozzles

   ─────────────────────────────────────────────────── ─── Continued front page    F-term (reference) 2H111 EA03 EA12 EA22 EA25 EA44                       FA01 FA12 FA14 FB42 FB43                       FB45 GA07                 5D029 JA04                 5D121 AA01 AA04 EE22 EE23 EE24                       EE28 GG20

Claims (13)

[Claims] 1. A coating liquid is discharged from a nozzle onto a coating medium which is rotated around an axis perpendicular to the coating surface,
A coating step of applying the coating solution to the coating surface by a centrifugal force acting on the coating solution on the coating surface, and a thin film step of solidifying the coating solution applied to the coating surface to form a thin film, The surface tension γ and the viscosity η of the coating liquid are set within a range of 20 mN / s ≦ γ <30 mN / s, 0.50 mPa · s ≦ η <30 mPa · s, and 0.50 ≦ γ / η. Spin coating method. 2. The spin coating composition according to claim 1, wherein the coating liquid contains at least one of a cyanine dye, an azo dye, a phthalocyanine dye, and a naphthalocyanine dye, and an organic solvent that dissolves the dye. Coating method. 3. The spin coating method according to claim 1, wherein the coating liquid contains an ultraviolet curable resin. 4. The distance D between the tip of the nozzle and the coating surface and the discharge pressure P applied to the coating liquid discharged from the nozzle are 1.0 mm ≦ D <5.0 mm, 0.1 kgf / cm ² The spin coating method according to claim 1, wherein the spin coating method is set within a range of ≦ P <1.5 kgf / cm ² . 5. The spin coating method according to claim 4, wherein the inner diameter r of the nozzle is set within a range of 0.20 mm ≦ r <2.00 mm. 6. The coating process according to claim 1, wherein the tip of the nozzle is made to face the coating surface, and the coating liquid is discharged in the axial direction of the coating surface. Spin coating method. 7. The discharge time t of the coating liquid is set within a range of 1.0 sec ≦ t <10 sec.
The spin coating method described. 8. The spin coating method according to claim 1, wherein in the coating step, the rotation speed S of the coating medium is set within a range of 10 rpm ≦ S <1000 rpm. . 9. In the coating step, the rotational speed S of the coating medium is changed to a plurality within the range of 10 rpm ≦ S <1000 rpm.
The spin coating method according to 5, 6, or 7. 10. After the coating step, a residual treatment step of accelerating the rotation speed of the coating medium to shake off the coating liquid from the coating medium is included, and the rotational speed S ′ of the coating medium in the residual treatment step is The spin coating method according to claim 8, wherein the spin coating method is set within a range of 1000 rpm ≦ S ′ ≦ 8000 rpm. 11. The coating step and the residual treatment step
Performed in an environment kept at a constant temperature T, the constant temperature T
Is set within a range of 15 ° C. ≦ T <30 ° C. 11. The spin coating method according to claim 1, wherein 12. A transparent coated medium having a coated surface, a reflective layer laminated on the coated surface of the coated medium, and a protective layer laminated on the reflective layer, at least the protective layer being provided. An optical disc formed by the spin coating method according to claim 1. 13. A transparent coated medium having a coated surface, a recording layer laminated on the coated surface of the coated medium, a reflective layer laminated on the recording layer, and a protective layer laminated on the reflective layer. An optical disc having at least one of the recording layer and the protective layer formed by the spin coating method according to claim 1.