JP4783193B2 - Coating film forming method - Google Patents

Description

This invention relates to coating film formation how the member having the function shape (e.g. an optical disc of the pre-groove).

In recent years, a so-called phase change type optical recording medium using a reversible phase change between a crystalline state and an amorphous state has been put to practical use as a recording medium for recording a large volume of digital data. As a recording material, a Ge—Sb—Te ternary alloy material represented by a compound composition such as Ge ₂ Sb ₂ Te ₅ having a GeTe—Sb ₂ Te ₃ pseudo binary system composition, and an Sb ₇₀ Te ₃₀ eutectic composition There are SbTe eutectic materials typified by Ag-In-Sb-Te, which are mainly composed of nearby materials. The former GeSbTe material is widely used as DVD-RAM, and the latter AgInSbTe eutectic material is widely used as CD-RW, DVD-RW, and DVD + RW. Each of these phase change optical recording media has a structure in which a lower protective layer, a recording layer, an upper protective layer, a reflective layer, etc. are laminated on a plastic substrate (light transmission layer) having a spiral or concentric groove. And recording / reproducing binary information by controlling the reflectivity by utilizing the optical constant change in the crystal and amorphous of the recording layer and the multiple interference of the laminated structure.

On the other hand, with the progress of digitization and the spread of broadband, the amount of information handled has increased, and a new recording system capable of recording and reproducing data at high density and high speed has been demanded. Against this background, by shortening the recording / reproducing wavelength and increasing the numerical aperture NA (Numerical Aperture), the focused beam diameter is reduced, the recorded mark size is reduced, and the recording density is increased and the speed is increased. An optical recording system aimed at the above has been proposed. For example, the current recordable DVD has a recording / reproducing wavelength λ = 650 to 660 nm, a numerical aperture NA = 0.65, and a recording capacity of 4.7 GB. However, the recording / reproducing wavelength λ is shortened to about 400 nm and the numerical aperture is increased. An optical recording system having a recording capacity of 20 GB or more with an NA of 0.85 has been proposed (Patent Documents 1 and 2).
As described above, in an optical recording system having a large numerical aperture, the tolerance for warping and tilting of the optical information recording medium, that is, the tilt margin is small. Therefore, the thickness of the light transmission layer is reduced in order to secure a sufficient tilt margin. There is a need to. For example, in the case of the above system with NA = 0.85 and λ = 405 nm, in order to ensure a sufficient tilt margin, it is required to make the light transmission layer as thin as about 100 μm.

  However, when the thickness of the light transmission layer is about 100 μm, when it is molded by an injection molding method such as polycarbonate as in the prior art, sufficient mechanical strength, plate thickness distribution, in-plane uniformity of optical characteristics, etc. There arises a problem that it becomes impossible to secure the. For this reason, Patent Documents 1 and 2 propose a structure in which a light transmission layer is provided on the side opposite to a conventional substrate. That is, a reflective layer, a dielectric layer, a phase change recording layer, a dielectric layer, and a light transmission layer are formed in this order on a substrate made of polycarbonate or the like to produce a phase change recording medium in which the light transmission layer is thinned. To do. In such a method, a substrate having a pregroove is first injection molded using a stamper, and then a reflective layer, a first dielectric layer, a phase change recording are formed on the surface of the substrate on which the pregroove is formed by a sputtering method or the like. A layer and a second dielectric layer are formed in this order. Then, a light transmission layer is formed on the surface of the second dielectric layer by spin coating of an ultraviolet curable resin or bonding of a film sheet. In the optical recording medium manufactured in this way, the recording / reproducing laser is incident from the opposite side of the substrate, so that the substrate can be made sufficiently thick. Therefore, if such an optical recording medium is used, it is possible to use a high NA optical recording medium head while sufficiently securing the mechanical strength of the substrate.

By the way, in the known spin coating method, a liquid material such as an ultraviolet curable resin is supplied near the center of the disk, the disk is rotated and the liquid material is spread by centrifugal force, and a coating of the liquid material is applied to the disk surface. This is a technique of forming with a uniform thickness. However, the technique of Patent Document 1 in which the light transmission layer is formed by the spin coating method has the following two problems.
The first problem is that it is difficult to obtain a uniform film thickness distribution by a method with good productivity. For example, in the case of the light transmission layer of a blue laser compatible disc having a recording / reproducing wavelength of about 400 nm, a film thickness distribution of 100 ± 2 μm is required in the recording area in order to suppress spherical aberration. In order to realize this, Patent Document 2 proposes a spin coating method that closes a central hole provided in the center of the disk.
However, in this method, it is necessary to clean and reuse the cap-shaped jig that closes the center hole with an organic solvent, etc., so a large amount of organic solvent is required to maintain the cleanliness of the jig, resulting in an increase in cost. In addition to this, there is a drawback that the load on the environment becomes high. In addition, as shown in the second problem described later, when a process of partially irradiating ultraviolet rays during spin coating is applied, the resin on the cap is cured by the wrapping ultraviolet rays, and the organic solvent It becomes difficult to remove by such as. When spin coating is performed with a capping jig that is partially washed with resin and is not sufficiently cleaned, thin portions with the resin remaining portion as a starting point are generated radially, which causes a decrease in yield.

The second problem is the rise of the resin at the outer peripheral edge of the disk called ski jump. The liquid resin dripped near the center of the disc by spin coating is applied to the entire disc by centrifugal force with a uniform film thickness. However, when the rotation stops and the centrifugal force disappears, the outer peripheral edge of the disc is affected by the surface tension of the liquid. This causes film thickness non-uniformity such as the coating film rising. Such a phenomenon becomes more prominent as the viscosity of the liquid material to be coated is higher. For example, in the light-transmitting film of the blue laser compatible disc, ski jumps reach the recording area on the outer periphery of the disc, leading to a problem of tracking failure and signal quality deterioration near the outer periphery. For this reason, the height of the ski jump at the outer peripheral end is preferably less than 10 μm.
Therefore, Patent Document 3 proposes a method of reducing the fluidity of the liquid material applied on the disk by irradiating ultraviolet light or the like before stopping the rotation of the disk in the spin coating process. Although this method can reduce ski jump at the outer peripheral edge, it is not sufficient. In addition, in the case of this method, the irradiated ultraviolet light is also irradiated to the resin recovery tray disposed around the disk in the spin coater, so that the resin adhering to the tray is cured and it is difficult to recycle the resin. There was a problem of becoming. Therefore, it becomes necessary to clean the collection tray, and the utilization rate of the resin deteriorates, which causes an increase in the cost of the recording medium.

In general, a substrate of an information recording medium is manufactured by an injection molding method using a stamper (mold) on which an uneven fine pattern is formed by photolithography. Then, after forming a magnetic film or phase change film on the substrate as a recording layer, the surface of the recording layer is covered with a resin for protection. As described above, spin coating is generally used as a coating method for an optical disc. In the case of spin coating, the thickness in the circumferential direction can be formed extremely uniformly, but the thickness tends to vary in the radial direction. When spin coating is performed on a dielectric film (for example, ZnS · SiO ₂ ) which is the outermost surface of the recording layer, the difference in film thickness becomes an optical phase difference, and interference fringes appear remarkably, which may adversely affect recording / reproduction characteristics. It has been confirmed. Furthermore, the bottom surface of the resin liquid to be spin-coated slides on the surface of the recording layer, but since the top surface is in contact with air, even a small particle floating in a clean room or a clean booth equipped with a HEPA filter. Functions as a nucleus of defects or halation, and it is difficult to form a low-defect coating film.

  As a conventional technique for forming a smooth coating film, the center lid of an optical disk is covered and resin is spin-coated from the center (Patent Documents 4 to 9), and a sheet without a center hole is placed and spin-coated. A cover layer is formed (Patent Document 10), and a sheet is bonded to a spin-coated resin (Patent Document 11). According to the methods of Patent Documents 5 to 9, the unevenness of thickness is suppressed by discharging the resin uniformly applied on the disk part of the blocking means in advance from the disk part onto the disk substrate by spin coating. However, even with this method, it is still the same that the resin is spread only by centrifugal force on the disk substrate whose upper surface is open. There are problems that the setting of conditions such as the viscosity of the resin to be determined and the rotation speed and rotation time of the disk substrate are complicated, and that the manufacturing process must be strictly controlled. The method of Patent Document 10 is to form a cover layer by placing a holeless sheet, and the sheet and the resin are integrated, and the concept is different from a so-called medium covering layer.

  In Patent Document 12, a photocurable resin is supplied to the plate surface of a disk substrate, a dummy substrate is set and rotated on the disk substrate, and then the resin is cured by irradiation with ultraviolet rays, and then the dummy substrate is peeled off. Thus, a method for obtaining a cover layer is disclosed. And as a material of the dummy substrate, a glass material is described in the claims, and a glass dummy substrate coated with a release agent is shown as an embodiment. However, it is extremely difficult to apply a release agent with a uniform thickness. To reduce the effect of thickness variation, reducing the release agent thickness tends to form islands, leaving no release agent area. Will adhere, so the cover layer (corresponding to the coating layer in the present invention) will be taken toward the dummy substrate. In addition, as a preferable aspect, although the interval setting portion is provided to regulate the thickness of the cover layer, the photo-curing resin does not spread radially evenly by contacting the setting portion on the inner periphery side, or the outer periphery The contact with the setting portion on the side causes the photocurable resin to bounce back into the recording area, resulting in defects such as halation. Furthermore, since the glass itself is originally liquid-tight, air enters the inner and outer peripheries after being shaken off, so that the resin is likely to return and a recording area where no coating layer is formed may occur. Moreover, the treatment with the release agent accelerates the liquid repellency, and it is difficult to form a cover layer with a highly uniform thickness as envisioned in the present invention over the entire surface. In addition, since the glass itself is highly rigid, there is also a drawback in that it tends to crack during peeling.

Japanese Patent No. 3241560 Japanese Patent Application Laid-Open No. 11-213459 JP 2002-319192 A JP-A-2005-141816 JP 2005-108375 A JP-A-2005-85403 JP 2003-326535 A JP 2003-16702 A JP 2003-22586 A JP 2003-242694 A JP 2002-288895 A JP 2004-134050 A

The present invention uniformly and smoothes the thickness of a light or thermosetting resin layer for covering a member to be coated, particularly a member having a functional shape (for example, a pregroove of an optical disk), without generating bubbles, coating film forming method capable of forming a high-quality coating film, further, the does not generate large warp by covering both sides of the member to be coated target mitigate the effects of shrinkage during curing the coating film formed how For the purpose of provision . Here, uniform and smoothing the thickness means that the variation in thickness in an arbitrary 1/100 circumferential section in the circumferential direction is 0.1 μm or less at an arbitrary radial position.

The above problems are solved by the following inventions 1) to 6 ) (hereinafter referred to as the present inventions 1 to 6 ).
1) Applying liquid heat or photo-curing resin in an annular shape to a member to be coated, and then applying a centrifugal force to the curable resin to form a flat surface A smooth substrate made of a material having rigidity to be placed is placed in contact with liquid, and a centrifugal force is applied to flatten the smooth substrate, while spreading the curable resin to the peripheral edge of the member to be coated. A method for forming a coating film, which is then cured and then peeled off the smooth substrate.
2) Applying liquid heat or photo-curing resin in an annular shape to the member to be coated, and flattening it by applying centrifugal force to the curable resin. A flat substrate made of a material having rigidity to be placed is placed in contact with the liquid, and a centrifugal force is applied to flatten the smooth substrate, while the curable resin is provided on the member to be coated or the smooth substrate. A coating film forming method, comprising: spreading to a stretch restraining portion; shaking off by centrifugal force; then curing the curable resin; and then peeling the smooth substrate.
3) Apply a liquid heat or photo-curing resin in an annular shape to the member to be coated, and then apply a centrifugal force to the curable resin to make it flat. A smooth substrate A made of a material having rigidity to be placed is placed and contacted, and a centrifugal force is applied to flatten the smooth substrate A while spreading the curable resin to the peripheral edge of the member to be coated. In the same manner, apply a liquid heat or photo-curing resin in an annular shape to the opposite surface in a state where it is not cured, and then apply a centrifugal force to the curable resin so that it is peelable. By placing a smooth substrate B made of a material having a rigidity to be flattened and bringing it into contact with liquid and applying a centrifugal force to flatten the smooth substrate B, the peripheral edge of a member to be coated with the curable resin After spreading the film, the curable resin on both sides is cured, and then the smooth substrates A and B are peeled off. A coating film forming method characterized by the above.
4) The coating film forming method according to claim 3, wherein the curable resins on both sides are simultaneously cured, and then the smooth substrates A and B are peeled off.
5) Apply a liquid heat or photo-curing resin in an annular shape to the member to be coated, and then apply a centrifugal force to the curable resin to make it flat. A smooth substrate A made of a material having rigidity to be placed is placed in contact with the liquid, and a centrifugal force is applied to flatten the smooth substrate A, while the curable resin is provided on the member to be coated or the smooth substrate A. After spreading to the spread restraint part and shaking off by centrifugal force, liquid heat or photo-curing resin is similarly applied in an annular shape on the opposite surface in a state where it is not cured, and the curing is performed thereon. A smooth substrate B made of a material having a releasability with respect to the conductive resin and having a rigidity that is flattened by applying a centrifugal force is placed on and in contact with the liquid, and a centrifugal force is applied to flatten the smooth substrate B. While, the curable resin to the member to be coated or the spread restraint provided on the smooth substrate B A coating film forming method, comprising: spreading and shaking off by centrifugal force; curing the curable resins on both sides; and then peeling off the smooth substrates A and B.
6) At least one of the member to be coated, the curable resin, and the smooth substrate in at least one of the stages before coating, during coating, and spreading of the heat or photocurable resin, The method for forming a coating film according to any one of 1) to 5), further comprising a step of applying heat energy concentrically with respect to the rotation center when the curable resin is applied in an annular shape.

Hereinafter, the present invention will be described in detail.
An important feature of the present invention is that a smooth substrate having rigidity that is flattened by applying a centrifugal force is used in a state of being flattened by applying a centrifugal force . It is possible to make the smooth substrate and the smooth substrate face each other substantially in parallel, and the heat or photo-curing resin applied in an annular shape using the parallel space is used as the peripheral end of the member or the spreading restraint portion. It is possible to extend to. And like this invention 1, when a smooth substrate is peeled after irradiating a heat | fever or light and hardening resin, a coating film with few defects and uniform thickness can be formed. However, in the case of forming a coating layer on the other surface of the member, or in the case of a flexible member, there is a concern that the disk-shaped member may bend due to the curing shrinkage of the resin and the servo characteristics may be deteriorated. .
Therefore, as in the case of the present invention 3, as in the case of the present invention 1, the smooth substrate A is placed and brought into contact with liquid, and a centrifugal force is applied to flatten the smooth substrate A while covering the curable resin . After spreading to the peripheral edge of the member to be covered, liquid heat or photo-curing resin is similarly applied in an annular shape to the opposite surface without being cured, and the curable resin is further coated thereon. While placing a smooth substrate B made of a material that has a releasability and has a rigidity that flattens by applying centrifugal force, the liquid is placed in contact with the solution, and centrifugal force is applied to flatten the smooth substrate B. The curable resin is spread to a member to be coated or a spread restraint provided on the smooth substrate B, and after being shaken off by centrifugal force, heat or light energy is irradiated to cure the curable resin on both sides, Next, if the smooth substrates A and B are peeled off, the thickness of the coating film can be made uniform and smooth. , By mitigating the effects of curing shrinkage upon, without and to generate a bubble without significant warping, it can form a high-quality coating.

The size of the smooth substrate is usually the same as that of the member. Although it is necessary to use what has peelability with respect to a heat | fever or photocurable resin for a smooth substrate, the peelability here is a level which can be easily peeled, for example using a cellophane tape. In the present invention, the term “flattening” refers to, for example, an optical disc, which is flat to some extent when the ratio (H / R) between the height difference H between the central portion and the peripheral portion and the radius R is 0.1 or less. Means that. The rigidity in the present invention means Young's modulus x (thickness / radius) ³ defined by a material dynamics cantilever, and the rigidity of the smooth substrate is preferably in the range of 5 to 5000 Pa. . Within this range, an appropriate tension is supplied to the substrate itself due to the centrifugal force at the time of swinging, and thus flattening is promoted.
The smoothness of the smooth substrate is such that the thickness variation in an arbitrary 1/100 circumferential section in the circumferential direction is 0.1 μm or less at an arbitrary radial position.
Examples of the material for the smooth substrate that satisfies the various requirements as described above include Toyobo Cosmo Shine PET. Examples of thermosetting resins include liquid polyester resins, epoxy resins, acrylic resins, urethane resins, melamine resins, and mixtures thereof. Examples of the photocurable resin include oligomers (low polymer) such as epoxy acrylate and urethane acrylate.

  In general, when a curable resin such as 2P (photopolymer) is applied using a barrel or a valve tank, the pressure tends to fluctuate according to the decrease in the internal volume, and the coating amount fluctuates according to the pressure fluctuation. It is difficult to apply a curable resin having a uniform coating width (amount) in an annular shape, and thickness variations cannot be made uniform. Therefore, a plunger pump is used to make the ring width of the coating resin uniform. Since the plunger always moves forward and backward with a constant stroke, a desired coating amount can be stably supplied, annular coating having a uniform coating width is always possible, and the thickness of the cured resin film can be made uniform. When coating on a member, it is desirable that the distance between the member and the dispenser needle is 0.1 to 30 mm. If it is this range, the coating | coated with the uniform width | variety of an annular ring is always possible in 1 round. If the distance is closer than 0.1 mm, the tip of the dispenser needle may interfere with the member due to variations in the thickness of the member, and the functional shape may be damaged. If it exceeds 30 mm, the coating width of the curable resin in the initial stage of coating becomes larger than the width of the original ring, and it is difficult to obtain a uniform thickness due to variations in the width of the ring in one round, and bubbles are involved. It is easy to get up.

As in the present inventions 2 and 5, it is preferable to provide a spread restraining portion on a member to be coated or a smooth substrate because the innermost circumference of the spread of the resin can be easily held in a perfect circle after the liquid contact. Since the spread resin is temporarily restrained by the spread restraint portion by the surface tension, it becomes a perfect circle. After that, if swung all at once, the spread of the resin spreads concentrically at a high speed, so that a coating film having a uniform thickness can be formed. The position where the spreading restraint portion is provided may be determined as appropriate in accordance with the range in which the resin is spread. For example, in the case of an optical disc, the position is inside the recording area. Examples of the shape of the spread restricting portion include concentric grooves and microprojection patterns formed by lithography (see FIGS. 1 to 3 and FIGS. 19 to 20).
An example of the process in which the coating film hardly entraps bubbles is a technique for reducing the contact area of the smooth substrate in contact with the coating resin. In general, when a voltage is applied to the resin material from the outside, the resin itself is polarized and the tip of the resin becomes sharp. As a result of intensive studies, it has been found that when a voltage of 2.5 kV or more is applied, the liquid contact area with the smooth substrate can be reduced and bubbles are not easily involved.
The viscosity of the heat or photocurable resin is about 10 to 10,000 mPa · s. Within this range, the smooth substrate flattened by the centrifugal force can be held flat until it is cured after the rotation is stopped, and this is preferable because the thickness of the coating film after curing and peeling off the smooth substrate can be easily made uniform. A more preferable viscosity range is 10 to 1000 mPa · s because uniform stretching is possible without assisting by application of thermal energy at the time of spreading after the annular coating.

The present invention 6 is suitable as a method for forming a light transmission layer of an optical information recording medium for recording / reproducing using a high NA optical system having a recording / reproducing wavelength of 405 ± 15 nm and a numerical aperture NA = 0.85 ± 0.5 of an objective lens. It is. In general, in a high NA optical system, coma aberration (inversely proportional to the product of the third power of NA and the thickness of the light transmission layer) becomes large, and thus it is necessary to reduce the thickness of the light transmission layer. An example of such an optical disc system is the Blu-ray disc standard. In this standard, 100 ± 2 μm is required as the film thickness distribution of the light transmission layer. When such a light-transmitting layer having a thickness of 100 μm is formed by the methods of the present invention 1 to 5 , it is necessary to increase the viscosity of the heat or photo-curing resin to 1000 to several thousand mPa · s. It becomes difficult to obtain a film thickness uniformity of 100 ± 2 μm only by the rigidity of the smooth substrate.

  Therefore, at least one of the optical disk, the curable resin, and the smooth substrate, which is a member to be coated, in at least one stage of coating or spreading before applying the heat or photocurable resin. On the other hand, it is preferable to apply heat energy concentrically with respect to the center of rotation when the curable resin is coated in an annular shape. Thereby, the resin temperature of a heating part can be raised, a viscosity can be lowered | hung, and the film thickness of an outer peripheral part can be made thinner than this part. The application of thermal energy may be performed at any timing before coating the resin, during coating, or during spreading, and these may be used in combination. For example, if thermal energy is applied to the vicinity of the center of the optical disk substrate while coating the resin, this portion is caused by heat conduction from the optical disk substrate when the smooth substrate is placed and the resin is spread by spin coating. Since the temperature of the resin passing therethrough is higher than the inner circumference and the viscosity is lowered, the film thickness from the middle circumference to the outer circumference can be flattened (thinned) compared to the case where no thermal energy is applied. Also, with respect to the above-described ski jump, the resin swell does not remain due to the flattening action of the placed smooth substrate. The target to which thermal energy is applied may be any of an optical disk (substrate), heat or photo-curing resin, and a smooth substrate, and two or more may be heated simultaneously as necessary.

A method of applying thermal energy in the above concentric manner will be described.
It is desirable that the film thickness distribution of the light transmission layer is uniform particularly in the scanning direction of the pickup of the optical disk drive device. Therefore, ideally, it is desirable to have a desired temperature distribution that is uniform in the circumferential direction of the groove groove and concentrically with respect to the center of the circle. However, in actual production, a thermal energy source with no temporal illuminance change is moved relatively in the circumferential direction of the optical disk substrate, and a substantially concentric temperature distribution is applied to the optical disk substrate with respect to the rotation center of the optical disk substrate. That's fine. Therefore, the concentric shape in the sixth aspect of the present invention does not necessarily have to be concentric as long as it is literally, as long as it can provide a substantially concentric temperature distribution. More simply, a thermal energy source such as an infrared lamp or a halogen lamp may be fixed on the optical disk substrate, and the optical disk substrate may be heated in the circumferential direction while rotating the optical disk substrate. At this time, in order to eliminate the temperature distribution in the circumferential direction, the optical disk substrate is rotated at a rotation speed such that the energy irradiation portion is sufficiently averagely heated with respect to the heating time (irradiation time), or the thermal energy source is turned on. It is good to arrange a plurality in the circumferential direction. What temperature distribution should be given to the optical disk substrate depends on the viscosity of the resin and its temperature-viscosity characteristics, the rigidity of the smooth substrate to be placed, the swing-off time, the number of revolutions, etc. select.

The temperature distribution obtained by the rotation of the optical disk substrate and the relative movement of the thermal energy source as described above is substantially concentric with respect to the rotation center of the optical disk substrate, and the thickness of the light transmission layer in the circumferential direction is 100 ± 2 μm or less. An optical recording medium can be obtained that can be easily obtained and in which the reflectance fluctuation in the circumferential direction and the fluctuation in the inner circumference of the jitter are in a range where there is no practical problem.
Note that the thermal energy source is not limited to the lamps described above, and a fluid such as a heated gas may be sprayed, or an electromagnetic wave such as a microwave may be used.
According to the above method, an optical disc capable of high-quality high-density recording / reproduction with a non-uniform thickness of the light-transmitting layer, in particular, no ski jumps on the outer periphery of the medium, is inexpensive and has a higher yield than conventional center mask methods. Can be provided.

FIG. 6 shows a configuration example of an optical information recording medium having a light transmission layer formed by the coating film forming method of the present invention.
The substrate is manufactured by injection molding of a resin such as polycarbonate, acrylic, or polyolefin, and has a spiral groove on the information recording layer lamination side. In the recording medium of FIG. 6, since the recording / reproducing laser beam is incident from the light transmitting layer side, the substrate material does not necessarily need to be light-transmitting, and has mechanical characteristics such as groove groove transferability and warpage. A good molding material can be selected, but usually a polycarbonate resin that has a proven record in CDs and DVDs is used.
The information recording layer is a phase change information recording layer containing a phase change recording material, or a write-once information recording layer containing a dye material or an inorganic material. In the case of the phase change type information recording layer, a reflective layer, a first dielectric layer, a recording layer, and a second dielectric layer are formed on a substrate in this order by a known sputtering method.
The reflective layer is preferably an Ag alloy containing Ag as a main component, and has a sufficient cooling ability, so that the film thickness is about 100 to 250 nm. Specific examples of the Ag alloy include Ag-Bi, Ag-In, Ag-Pd-Cu, and Ag-Nd-Cu. The additive element is added to suppress aggregation and crystal grain growth under high temperature environment of the Ag film, but the total content is 3 atomic% or less so as not to impair the good thermal conductivity of Ag. It is desirable that

For the first dielectric layer and the second dielectric layer, a high melting point material such as a metal or semiconductor oxide, sulfide, nitride, carbide or the like having high transparency is used. _{Specifically, SiOx, ZnO, SnO 2,} Al 2 O 3, TiO 2, In 2 O 3, MgO, ZrO 2, Ta oxides such _{2 O 5, Si 3 N 4} , AlN, TiN, BN, Examples include nitrides such as ZrN, sulfides such as ZnS and TaS ₄ , and carbides such as SiC, TaC, B ₄ C, WC, TiC, and ZrC, and they are used as a single body or a mixture, or as a multilayer structure composed of two or more layers. be able to. Preferred materials are determined taking into account refractive index, thermal conductivity, chemical stability, mechanical strength, adhesion, and the like. Among these, a mixed film with SiO ₂ containing 60 to 90 mol% of ZnS is preferable because it does not cause repeated recording, crystallization of the film itself in a high temperature environment, chemical change, and film deformation. In addition, since the thermal conductivity is as low as 0.5 W / mK or less, the dielectric film in contact with the recording layer is also advantageous in that the melting peak temperature of the recording layer is kept high and it is advantageous for forming an amorphous mark with a high degree of modulation. As the most suitable.

For the phase change recording layer, a well-known GeTe—Sb ₂ Te ₃ pseudo binary material represented by Ge ₂ Sb ₂ Te ₅ or an SbTe eutectic material represented by AgInSbTeGe can be used. In particular, when an optical system having a recording / reproducing wavelength of 405 ± 15 nm and an objective lens numerical aperture NA = 0.85 ± 0.5 is used, a phase change recording material mainly composed of an alloy of Ge, Sb, Sn and Mn However, it is preferable because of excellent reproduction light stability and storage reliability (amorphous mark stability). Preferred composition ranges of the respective elements are 5 ≦ Ge ≦ 20 atomic%, 45 ≦ Sb ≦ 70 atomic%, 10 ≦ Sn ≦ 20 atomic%, and 0 <Mn ≦ 20 atomic%. Since Ge raises the crystallization temperature and improves the storage stability, but repeatedly deteriorates the recording characteristics, it is desirable not to exceed 20 atomic%. On the contrary, in order to ensure the storage reliability in a high temperature and high humidity environment, 5 atomic% or more is required. Sn needs to be contained in an amount of 10 atomic% or more in order to obtain sufficient reflectance and contrast at a wavelength of 405 nm. However, if there is too much Sn, the recording characteristics are impaired as in the case of Ge, so it is desirable that it does not exceed 20 atomic%. Since Mn has a smaller adverse effect on reflectivity reduction and recording jitter than Ge, Mn is added in place of Ge when the crystallization speed is reduced. The amount of Mn added is preferably not more than 20 atomic% because it deteriorates the repeated recording characteristics like Ge. Since Sn and Sb are elements that increase the crystallization speed and Ge and Mn are elements that decrease the crystallization speed, the composition ratio of each element is optimized in consideration of the overall recording characteristics and the target recording linear velocity. Basically, the target recording linear velocity is designed by the Ge—Sb system, and Mn is substituted for Ge and Sn is substituted for Sb by appropriate amounts. If Sb + Sn exceeds 90 atomic%, the crystallization speed becomes too fast and it becomes difficult to form an amorphous mark. Therefore, the upper limit of Sb is preferably Sb ≦ 70 atomic%. Further, in order to obtain a recording linear velocity of 5 to 30 m / s at 10 ≦ Sn ≦ 20 atomic%, 45 atomic% ≦ Sb is preferable. Alternatively, the total amount of Ge, Sb, Sn, and Mn may be 95 atomic% or more, and may include a fifth element that is 5 atomic% or less for improving recording characteristics, storage reliability, and the like.

The light transmission layer is composed of an ultraviolet curable resin layer or the like using the coating film forming method of the present invention. A hard coat layer may be provided on the light transmission layer by a spin coat method or the like. When recording / reproducing is performed using an optical system having a recording / reproducing wavelength of 405 ± 15 nm and an objective lens numerical aperture NA = 0.85 ± 0.5, the thickness of the light transmission layer for securing a sufficient tilt margin is 5 -200 micrometers is preferable, More preferably, it is 5-120 micrometers.
The configuration example of the phase change optical information recording medium has been described above, but the information recording layer may be a write-once dye recording layer or an inorganic recording layer in addition to the phase change recording layer. Further, it may be a multilayer recording medium having two or more information recording layers via an intermediate layer.

According to the present invention, the thickness of a light or thermosetting resin film for covering a member to be coated, particularly a member having a functional shape (for example, a pregroove of an optical disk) is made uniform and smooth, and bubbles are generated. Coating film forming method that can form a high quality coating film, and further, a coating film forming method that does not generate a large warp by covering both surfaces of a member to be coated and reducing the effect of shrinkage during curing Can provide law .

  EXAMPLES Hereinafter, although an Example and a comparative example demonstrate this invention further more concretely, this invention is not limited by these Examples.

Example 1
A transfer disk substrate having a diameter of 120 mm was obtained by injection molding using a stamper having a pre-groove shape formed by photolithography.
On the transfer surface of the disk substrate, an Ag reflective layer having a thickness of 120 nm, a first dielectric layer made of ZnS—SiO _{2 having} a thickness of 12 nm, a phase change recording layer made of Sb ₃ Te having a thickness of 14 nm, and a film are formed by sputtering. A second dielectric layer made of ZnS—SiO _{2 having a} thickness of 45 nm is formed in order, and a photocurable resin (Dainippon Chemical Die, manufactured by Unicontrols; Hiberpump CV) is used on the second dielectric layer. Cure Clear SD-715, viscosity 43 mPa · s) was applied in an annular shape to 0.5 cc.
Next, on the coated surface, a smooth substrate, a PET (polyethylene terephthalate) substrate having a diameter of 120 mm and a thickness of 0.1 mm (Toyobo Cosmo Shine A4100, the substrate rigidity from the inner periphery to the outer periphery is in the range of 31 to 339 mPa · s. And was shaken off at 3000 rpm for 20 seconds, and then irradiated with a UV lamp made by Fusion for 5 seconds to cure the photocurable resin.
Then, when the photocurable resin film and the PET substrate were peeled off, an optical disk having a coating film with a smooth surface as shown in FIG. 12 (photograph) was obtained.
Further, when the phase change recording layer was initialized, it was initialized over the entire surface.
The appearance of the surface of the obtained coating film was smooth, the focus and tracking were good, and the reproduction signal characteristics were good as shown in the RF signal in FIG. 18 (photograph).

Example 2
In place of the transfer disk substrate of Example 1, a transfer disk substrate in which concentric grooves for constraining curable resin spread were formed by YAG laser in the inner periphery from the recording area of the substrate in addition to the pregroove shape was used. In the same manner as in Example 1, a phase change recording layer was formed on the transfer surface, and a photocurable resin was applied thereon (see FIG. 2).
Next, a DC voltage of 2.5 kV was applied between the coated surface and a PET substrate (Toyobo Cosmo Shine A4100) placed as a smooth substrate. When the coating resin was polarized and the apex was raised, the PET substrate was placed and contacted.
When the photocurable resin reached the concentric grooves due to the capillary phenomenon, the photocurable resin was cured by irradiating at 3000 rpm for 20 seconds and irradiating with a fusion UV lamp for 5 seconds.
Thereafter, when the photocurable resin film and the PET substrate were peeled off, an optical disk having a coating film with a smooth surface as shown in FIG. 4 and a perfect inner circle as shown in FIG. 4 was obtained. It was.
Further, when the phase change recording layer was initialized, it was initialized over the entire surface.
The appearance of the surface of the obtained coating film was smooth, the focus and tracking were good, and the reproduction signal characteristics were good as in Example 1.
As shown in FIG. 3, the concentric grooves exhibit the same function even if they are formed on a smooth substrate placed on and in contact with the curable resin.

Example 3
A coating film was formed in the same manner as in Example 1 except that a PET substrate having different rigidity was used as the smooth substrate. Table 1 shows the relationship between the thickness and the rigidity of the smooth substrate. When the thickness is between 0.05 and 0.3 mm, the rigidity at the radial position of 25 to 55 mm is in a grayed portion, that is, the substrate rigidity is In the range of about 5 to 5000 Pa, flattening in the present invention described in paragraph 0013 was possible by centrifugal force. And if it was this range, the optical disk which has the same coating film as Example 1 was obtained. Within this range, the phase change recording layer can be initialized over the entire surface, the appearance of the surface of the obtained coating film is smooth, and the focus, tracking, and reproduction signal characteristics are also good as in the first embodiment. there were.
Furthermore, since the viscosity of the photo-curing resin is in the range of 10 to 10,000 mPa · s, the smooth substrate flattened by centrifugal force can be held flat until it is cured after the rotation is stopped. The thickness of the coating film after peeling off the substrate could be made uniform.
When the phase change recording layer was initialized, it could be initialized over the entire surface, the appearance of the surface of the obtained coating film was smooth, the focus and tracking were good, and the reproduction signal characteristics were also the case of Example 1 (FIG. As in (18), the RF signal was good.

Example 4
Change photocurable resin to urea resin (Matsushita Electric Works: National Light Urea Resin A type) which is thermosetting resin, shake it off at 5000rpm for 20 seconds, and then heat at 160 ° C for 30 minutes to heat the thermosetting resin. An optical disc having a coating film was produced in the same manner as in Example 1 except for the cured point.
As a result, as in Example 1, the surface appearance of the obtained coating film was smooth, and the focus, tracking, and reproduction signal characteristics were good.

Example 5
Except that the transfer molding substrate was obtained by photolithography using a stamper in which a curable resin spreading restraint spiral pattern was formed at the inner periphery of the pregroove area at the same time as the pregroove, the same as in Example 2. An optical disc having a covering film was produced (see FIG. 1).
As a result, as in Example 2, the surface appearance of the obtained coating film was smooth, and the focus, tracking, and reproduction signal characteristics were good.

Comparative Example 1
An optical disk having a coating film in the same manner as in Example 1 except that the photocurable resin was applied without placing the PET substrate on the substrate and then immediately shaken off and irradiated with ultraviolet rays to form a coating film. Was made.
As a result, as shown in FIG. 13 (photograph), interference fringes depending on thickness variation in the radial direction are seen in the coating film, and if the innermost circumference of the spread is a perfect circle as shown in FIG. There wasn't.
In addition, an area that cannot be initialized occurred in the recording layer, and recording / reproduction on the entire surface of the disk could not be performed.

Comparative Example 2
An optical disk having a coating film was prepared in the same manner as in Example 1 except that a coating film was formed by placing and contacting a PC (polycarbonate) substrate (Teijin Pure Ace) instead of the PET substrate. .
In this case, if the PC substrate is peeled after curing the photo-curable resin, the adhesion is strong, and as shown in FIG. 14 (photo), the coating film is brought to the PC substrate side on one side, and the quality A good coating film could not be formed.

Comparative Example 3
An optical disk having a coating film was prepared in the same manner as in Example 1 except that a coating film was formed by placing and contacting a PE (polyethylene) substrate instead of the PET substrate.
In this case, after curing the photocurable resin, when the PE substrate is to be peeled off, the adhesion is strong, and as shown in FIG. 15 (photo), the coating film is brought to the PE film substrate side on one side, A coating film with good quality could not be formed.

Comparative Example 4
An optical disk having a coating film was produced in the same manner as in Example 1 except that a coating film was formed by placing and contacting the glass substrate instead of the PET substrate.
In this case, the photocurable resin easily repels the glass substrate, and when the rotation is stopped, the spread resin moves toward the outer periphery at the inner diameter and toward the inner periphery at the outer diameter to form a coating film on the entire surface of the disk. It was difficult. Further, the balance of peeling was not stable, and a part of the recording layer was brought to the glass substrate side (that is, repellency and excessive adhesion coexisted). This is because the recording layer cannot be peeled off while being warped like the substrate of the present invention having an appropriate rigidity, so it is considered that the recording layer was peeled off by being strongly pulled by the coating film at the time of peeling. Could not be formed (see FIGS. 16 to 17 = photographs).

Example 6
Prepare a polycarbonate substrate (product name ST3000, manufactured by Teijin Bayer Polytech) having a groove depth of 21 mm, a groove width of 0.16 μm, a groove groove having a track pitch of 0.32 μm, a thickness of 1.1 mm, and a diameter of 120 mm. The following laminated films were sequentially formed by sputtering (numbers in parentheses are film thicknesses).
Reflective layer Ag-0.5 atomic% Bi (140 nm)
First dielectric layer ZnS 20 mol% SiO ₂ (8 nm)
Phase change recording layer Ge ₁₁ Sb _62.5 Sn ₂₀ Mn _6.5 (14 nm)
Second dielectric layer ZnS / 30 mol% SiO ₂ (40 nm)
Next, an ultraviolet curable resin (Nippon Kayaku BRD-130) is supplied in an annular shape, and a PET substrate (Toyobo Cosmo Shine A4100) is placed and wetted in the same manner as in Example 1, and is placed in the medium with an infrared lamp device. While heating around the circumference, the resin was shaken off at a rotation speed of 1700 rpm for 6 seconds. In the infrared lamp device, as shown in FIG. 11, a plurality of infrared lamps are arranged at equal intervals on the circumference, and the light is shielded on the rotation center of the substrate so that the illuminance to the central portion of the disk substrate becomes relatively small. A structure is provided in which a portion is provided.
Next, the resin was cured by irradiating with 1000 mJ / cm ² of ultraviolet rays, and then the PET substrate was peeled off to obtain an optical disk having the structure shown in FIG.
When the film thickness distribution of the light transmission layer was examined with an interference film thickness measuring device ETA-RT (manufactured by STEAG ETA-Optik), as shown in FIG. It was less than 100 ± 2.0 μm within the -ray disc standard, and as shown in FIG. 8, there was no bulge of the resin at the outer peripheral edge, that is, no ski jump. Note that the shape of the sag at the outer peripheral edge of the substrate in FIG. 8 reflects the shape that has been chamfered at the time of molding, and is not due to fluctuations in the film thickness of the light transmission layer.
Furthermore, when signal evaluation was performed with a recording / reproducing apparatus (ODU-1000 manufactured by Pulstek), there was no fluctuation in reflectance within the circumference, and recording jitter was 6.5% or less over the entire surface.

Comparative Example 5
Except that the infrared lamp was not used, an optical disk was manufactured in the same manner as in Example 6 and the film thickness distribution of the light transmission layer was examined. As a result, as shown in FIG. The ray disc standard could not be satisfied.
In this comparative example, in order to manufacture an optical disc that satisfies the Blu-ray disc standard in which the film thickness distribution of the light transmission layer is within 100 ± 2.0 μm, the step of applying the thermal energy of the present invention 6 is required. This indicates that there is, and as is apparent from Examples 1 to 5 described above, it is not necessary to apply thermal energy in a normal case.

Comparative Example 6
The same substrate and information recording layer as in Example 1 were prepared, and a center mask with a diameter of 22.5 mm was fitted into the center hole of the substrate, and UV curable resin BRD-130 was dropped from above the mask. The resin was shaken off at 1800 rpm for 5 seconds. At this time, the entire surface of the disk was irradiated with ultraviolet rays of 500 mJ / cm ² while shielding the center mask portion for 1 second before stopping the rotation. Next, the center mask was removed, and the resin was completely cured by irradiating with 600 mJ / cm ² of ultraviolet rays to obtain an optical disk having the structure shown in FIG.
When the film thickness distribution was examined in the same manner as in Example 6, as shown in FIG. 10, a ski jump having a width of about 0.8 mm and a height of about 30 μm remained at the outermost peripheral edge of the substrate.

Example 7
A transfer disk substrate having a diameter of 120 mm was obtained by injection molding using a stamper having a pre-groove shape formed by photolithography.
On the transfer surface of the disk substrate, an Ag reflective layer having a thickness of 120 nm, a first dielectric layer made of ZnS—SiO _{2 having} a thickness of 12 nm, a phase change recording layer made of Sb ₃ Te having a thickness of 14 nm, and a film are formed by sputtering. A second dielectric layer made of ZnS—SiO _{2 having a} thickness of 45 nm is formed in order, and a photocurable resin (Dainippon Chemical Die, manufactured by Unicontrols; Hiberpump CV) is used on the second dielectric layer. Cure Clear SD-715, viscosity 43 mPa · s) was applied in an annular shape to 0.5 cc.
Next, a 120 mm diameter, 0.1 mm thick PET (polyethylene terephthalate) substrate (Toyobo Cosmo Shine A4100, the substrate rigidity from the inner periphery to the outer periphery is in the range of 31 to 339 Pa) on the coated surface is a smooth substrate A. As a result, the solution was shaken for 20 seconds at 3000 rpm.
In that state, the photo-curing resin was similarly applied to the opposite surface of the optical disk in an annular shape, and then the PET substrate was placed on the coated surface as a smooth substrate B, and was shaken off at 3000 rpm for 20 seconds. .
Subsequently, each photocurable resin was hardened by irradiating both surfaces with a UV lamp manufactured by Fusion for 5 seconds.
Thereafter, when the PET substrate was peeled off, an optical disk having a coating film with smooth surfaces similar to that in Example 1 (see FIG. 12) was obtained. The mechanical properties (warpage) of the optical disk were good as shown in FIG. Note that the horizontal axis in FIG. 21 represents one round of the disk, and the vertical axis represents surface runout. When FIG. 21 is compared with FIG. 22 of Comparative Example 8 which will be described later, it can be seen that the surface shake is clearly smaller in FIG. This is based on the difference in the curing process of the photocurable resin, and in the case of this embodiment, the influence of the curing shrinkage of the photocurable resin is offset on both sides of the optical disk.
Further, when the phase change recording layer was initialized, it was initialized over the entire surface.
The surface appearance of the obtained coating film was smooth, the focus and tracking were good, and the reproduction signal characteristics were good as in Example 1 (see FIG. 18).

Example 8
An optical disc having coating films on both sides was produced by the steps shown in FIGS. 19- (1) and (2).
First, a transfer disk substrate having a diameter of 120 mm was obtained by injection molding using a stamper in which a curable resin spreading restraint spiral pattern was formed on the inner periphery of the pregroove area simultaneously with the pregroove by photolithography.
A reflective layer, a first dielectric layer, a phase change recording layer, and a second dielectric layer are formed in this order on the transfer surface of the disk substrate by sputtering in the same manner as in Example 7. 0.5 cc of curable resin was applied in an annular shape.
Next, a DC voltage of 2.5 kV was applied between the coated surface and the same PET substrate as that of Example 7 placed as the smooth substrate A. When polarization occurred in the coating resin and the apex was raised, the PET substrate was placed in contact with the solution and shaken off at 3000 rpm for 20 seconds.
In this state, a photo-curing resin is similarly applied to the opposite surface of the disk substrate in an annular shape and a DC voltage is applied, and then a PET substrate made of the same material as in Example 7 is placed as a smooth substrate B. Wetted. However, as the smooth substrate B, a substrate in which concentric grooves for restraining the spreading of the curable resin were formed with a YAG laser at a position corresponding to the inner periphery of the recording area of the transfer disk substrate was used. When the photocurable resin reached the concentric grooves by capillary action, it was shaken off at 3000 rpm for 20 seconds.
Subsequently, each photocurable resin was hardened by irradiating both surfaces with a fusion UV lamp for 5 seconds.
Thereafter, when the PET substrate was peeled off, the same surface as in the case of Example 1 (see FIG. 12) was smooth, and the coating innermost circumference as shown in FIG. An optical disc was obtained.
Further, when the phase change recording layer was initialized, it was initialized over the entire surface.
The appearance of the surface of the obtained coating film was smooth, the focus and tracking were good, and the reproduction signal characteristics were good as in the case of Example 1.
In addition, the same result was obtained even if the photocurable resin film formed by coating was irradiated simultaneously on both sides for 5 seconds by the process shown in FIG.

Example 9
An optical disc having coating films on both sides was prepared in the same manner as in Example 7 except that a PET substrate having different rigidity was used as the smooth substrate. The relationship between the thickness and the rigidity of the smooth substrate is as shown in Example 3, but also in this example, the same coating film as in Example 7 is obtained when the smooth substrate has a rigidity of 5 to 5000 Pa. It was. Within this range, the phase change recording layer can be initialized over the entire surface, the appearance of the surface of the obtained coating film is smooth, and the focus, tracking, and reproduction signal characteristics are also good as in Example 7. there were.
Furthermore, since the viscosity of the photo-curing resin is in the range of 10 to 10,000 mPa · s, the smooth substrate flattened by centrifugal force can be held flat until it is cured after the rotation is stopped. The thickness of the coating film after peeling off the substrate was made uniform.
When the phase change recording layer was initialized, it could be initialized over the entire surface, the appearance of the surface of the obtained coating film was smooth, the focus and tracking were good, and the reproduction signal characteristics were also the case of Example 1 (FIG. As in (18), the RF signal was good.

Example 10
The photo-curing resin was changed to urea resin (Matsushita Electric Works: National Light Urea Resin A type), which is a thermosetting resin, and coated on both sides in the same manner as in Example 7 under the condition of shaking off at 5000 rpm for 20 seconds. An optical disc having The heating condition after double-sided coating was 120 ° C. for 30 minutes.
As a result, as in Example 7, the surface appearance of the obtained coating film was smooth, and the focus, tracking, and reproduction signal characteristics were good.

Example 11
The stamper pregroove was held at 170 ° C. and 10 MPa for 10 minutes by a hot imprinting method, and transferred to a 95 μm thick PC (polycarbonate) film (Teijin Pure Ace). A phase change recording layer made of Sb ₃ Te with a film thickness of 14 nm was formed on the groove transfer surface by sputtering, and a coating film was formed on both surfaces in the same manner as in Example 7. Was obtained on both sides.
Further, when the phase change recording layer was initialized, it was initialized over the entire surface.
The appearance of the surface of the obtained coating film was smooth, the focus and tracking were good, and the reproduction signal characteristics were good in the RF signal as in Example 1 (see FIG. 18).

Comparative Example 7
Instead of the PET substrate, a coating film was formed in the same manner as in Example 7 except that a PC (polycarbonate) substrate (Teijin Pure Ace) was placed and contacted to form a coating film.
In this case, when the PC substrate is peeled off after the photocurable resin is cured, the adhesion is strong, and the coating film is held on the PC substrate side in the same manner as in Comparative Example 4 (see FIG. 17). As a result, it was not possible to form a coating film with good quality.

Comparative Example 8
In the same manner as in Example 7, a smooth substrate A (PET substrate) was placed on the coated surface and wetted at 3000 rpm for 20 seconds, and then irradiated with a UV lamp made by Fusion for 5 seconds to give a photocurable resin. Cured. Similarly, a photo-curing resin is coated in an annular shape on the opposite surface of the disk substrate, and a smooth substrate B (similar PET substrate) is placed on the surface and shaken for 20 seconds at 3000 rpm. The photocurable resin was cured by irradiating the lamp for 5 seconds.
That is, the seventh embodiment is different from the seventh embodiment in that the photocurable resin related to the smooth substrate A is cured before the operation of placing the smooth substrate B is started.
Thereafter, when the PET substrate was peeled off, an optical disk having a smooth coating film on both surfaces similar to that in Example 1 (see FIG. 12) was obtained. The mechanical properties of the optical disk were compared with Example 7. (See FIG. 22, vertical axis and horizontal axis are the same as in Example 7). As a result, the quality of the reproduction signal characteristic is degraded.

FIG. 10 is a diagram showing a coating film forming process of Example 5. (A) a step of coating a photocurable resin, (b) a step of placing and contacting a smooth substrate on the coated surface and spreading, (c) a step of shaking off and curing the photocurable resin, and (d) a smoothing step. A step of peeling the substrate. The figure which shows the coating film formation process of Example 2. FIG. (A) a step of coating a photocurable resin, (b) a step of placing and contacting a smooth substrate on the coated surface and spreading, (c) a step of shaking off and curing the photocurable resin, and (d) a smoothing step. A step of peeling the substrate. The figure which shows the coating film formation process at the time of providing the pattern for constriction (a concentric groove | channel) on a smooth substrate. (A) a step of coating a photocurable resin, (b) a step of placing and contacting a smooth substrate on the coated surface and spreading, (c) a step of shaking off and curing the photocurable resin, and (d) a smoothing step. A step of peeling the substrate. The figure which shows the state from which the coating film whose extension innermost periphery is a perfect circle was obtained in Example 2 and Example 8. FIG. The figure which shows the state which the spreading innermost periphery of the coating film did not become a perfect circle in the comparative example 1. FIG. The figure which shows the structural example of a phase change type | mold optical information recording medium. FIG. 10 is a diagram showing the result of examining the film thickness distribution of the light transmission layer of the optical disc of Example 6. FIG. 10 is a diagram showing that no ski jump occurs at the outer peripheral edge of the optical disc of Example 6. The figure which shows that the optical disk of the comparative example 5 was not satisfying the Blu-ray disc specification. The figure which shows that the ski jump remained in the outer periphery edge of the optical disk of the comparative example 6. FIG. FIG. 10 is a diagram showing a configuration of an infrared lamp device used in Example 6. The figure (photograph) which shows the state of the coating film of Example 1. FIG. The figure (photograph) which shows the state of the coating film of the comparative example 1. FIG. The figure (photograph) which shows the state of the coating film of the comparative example 2. FIG. The figure (photograph) which shows the state of the coating film of the comparative example 3. FIG. The figure (photograph) which shows the state of the coating film of the comparative example 4. The figure (photograph) which shows the state of the coating film of the comparative example 4. FIG. 2 is a diagram (photograph) showing an RF signal of an optical disk manufactured in Example 1. FIG. 10 shows a coating film forming process of Example 8. (A) a step of applying a photocurable resin to one surface of the optical disk, (b) a step of placing and contacting the smooth substrate A on the coated surface and spreading, (c) a step of shaking off the photocurable resin, (D) A step of applying a photocurable resin to the opposite surface of the optical disk. The figure which shows the coating film formation process of Example 8 (continuation). (E) A step of placing and contacting and spreading the smooth substrate B on which the concentric grooves for constraining the spreading of the curable resin are formed on the coated surface, (f) a step of shaking off the photocurable resin, (g) A step of peeling the smooth substrate A after curing the photocurable resin film in order of the smooth substrate A side and the smooth substrate B side; and (h) a step of peeling the smooth substrate B. In Example 8, the figure in the process in the case of light-irradiating the photocurable resin film formed by coating simultaneously on both surfaces. (F ′) a step of shaking off the photocurable resin on the smooth substrate B side, (g ′) a step of peeling the smooth substrate A after curing the photocurable resin film simultaneously on both sides, and (h ′) the smooth substrate B. The process of peeling. FIG. 10 is a diagram showing mechanical characteristics of the disc of Example 7. The figure which shows the mechanical characteristic of the disk of the comparative example 8. FIG.

Claims (6)

  The member to be coated is coated with a liquid heat or photo-curing resin in an annular shape, and is flattened by applying a centrifugal force to the curable resin having a peelability thereon. After placing a smooth substrate made of rigid material in contact with the liquid and applying a centrifugal force to flatten the smooth substrate, the curable resin is spread to the peripheral edge of the member to be coated. A method for forming a coating film, comprising curing and then peeling off the smooth substrate.   The member to be coated is coated with a liquid heat or photo-curing resin in an annular shape, and is flattened by applying a centrifugal force to the curable resin having a peelability thereon. A flat substrate made of rigid material is placed and contacted, and centrifugal force is applied to flatten the smooth substrate, while the curable resin is applied to a member to be coated or a smoothing restraint provided on the smooth substrate. A coating film forming method, comprising: spreading to a part, shaking off by centrifugal force, then curing the curable resin, and then peeling the smooth substrate.   The member to be coated is coated with a liquid heat or photo-curing resin in an annular shape, and is flattened by applying a centrifugal force to the curable resin having a peelability thereon. Placing the smooth substrate A made of a rigid material to make liquid contact, applying a centrifugal force, flattening the smooth substrate A, and spreading the curable resin to the peripheral edge of the member to be coated, By applying a liquid heat or photo-curing resin in an annular shape to the opposite surface in the same manner without curing, and applying a centrifugal force to the curable resin on the opposite surface. A smooth substrate B made of a material having flattening rigidity is placed and contacted, and centrifugal force is applied to flatten the smooth substrate B while spreading the curable resin to the peripheral edge of the member to be coated. After stretching, the curable resin on both sides is cured, and then the smooth substrates A and B are peeled off. Coating film forming method according to.   The method for forming a coating film according to claim 3, wherein the curable resins on both sides are simultaneously cured, and then the smooth substrates A and B are peeled off.   The member to be coated is coated with a liquid heat or photo-curing resin in an annular shape, and is flattened by applying a centrifugal force to the curable resin having a peelability thereon. A smooth substrate A made of a rigid material is placed and brought into contact with liquid, and a centrifugal force is applied to flatten the smooth substrate A, while the curable resin is provided on the member to be coated or the smooth substrate A. After spreading to the extension restraint part, shaking off by centrifugal force, and applying the liquid heat or photo-curing resin in an annular shape to the opposite surface in a state where it is not cured, on the curable resin While placing a smooth substrate B made of a material that has a releasability and has a rigidity that flattens by applying centrifugal force, the liquid is placed in contact with the solution, and centrifugal force is applied to flatten the smooth substrate B. The curable resin is spread to a member to be coated or a spreading restraint provided on the smooth substrate B Was, after throwing off by centrifugal force, the coating film forming method characterized in that curing the both surfaces of a curable resin and then peeling off the smooth substrate A, B.   At least one of the member to be coated, the curable resin, and the smooth substrate in at least one stage before coating, during coating, and spreading before the application of the heat or photo-curable resin, the curability The method for forming a coating film according to any one of claims 1 to 5, further comprising a step of applying heat energy concentrically with respect to a rotation center when the resin is coated in an annular shape.