JPH10199051A - Method and device for sticking disks to each other - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a highly reliable stuck, disk by flash-irradiating disks so that the integrated value of the flash-irradiated energy on the surface of a disk substrate at the outer side of an information disk substrate side is always larger than the value from the outer side of a dummy disk substrate side. SOLUTION: The lamp light sources are arranged on the both sides of a disk substrate which is made by sticking two disk substrates to each other. The sources have an irradiation device, which is an electric discharge mechanism that is able to repeatedly conduct flash irradiation. The irradiation is conducted so that the flash irradiation from the outer side of the information disk substrate side is larger in a preceding manner than the flash irradiation from the outer side of the dummy disk substrate side in terms of the integrated irradiation energy. For example, if the per flash irradiation energy form the both sides is same at the surfaces of the disk substrates, flash irradiation is conducted more than once from the outer side of the side having the information disk substrate, take a prescribed time difference and then, conduct flash irradiation from the outer side of the dummy substrate side for more than once.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for bonding two disk substrates each having an information recording layer on at least one side, and more particularly, to a digital video disk or digital versatile, particularly a bonding method. The present invention relates to a preferable manufacturing method of a disk (hereinafter, abbreviated as DVD). The present invention also relates to a method of bonding two disk substrates, each having an information recording layer on only one of the two, called DVD-5, even in a DVD.

[0002]

2. Description of the Related Art An ultraviolet curable resin is used as an adhesive,
A conventional method of bonding two plate-like objects is to first apply an ultraviolet-curable composition to the bonding surface uniformly by an existing technique, such as spin coating or screen printing, In this method, ultraviolet light was emitted and the light was cured by continuous irradiation.However, in this method, heat was generated due to the continuous light emission of the lamp. Therefore, there is a problem that the heat adversely affects the warpage and mechanical properties of the disk.

[0003] Alternatively, in the lamp of the type that emits light continuously, from the time of lighting until the intensity of light emission becomes stable,
Usually, it takes several minutes or more, so there is a problem that it cannot be easily turned on or off. Therefore, in the case of continuous production, the lamp must be kept on. For example, if the time required for one bonding (one cycle) (production cycle time) is 5 seconds, and if the time required for ultraviolet irradiation is 2 seconds, energy is wasted for the remaining 3 seconds. And there was also a problem that efficiency was poor.

Under such circumstances, as a method of attaching disks with low power consumption, small size and light weight in terms of equipment, and high productivity, a method of repeatedly flashing the ultraviolet rays has been proposed. According to such a method, not only low power consumption, small size and light weight, but also an advantage that a large-scale additional facility for cooling the lamp is not required is produced.

On the other hand, among the DVDs manufactured by bonding two disk substrates, in a disk called DVD-5, only one disk substrate has an information recording layer, and the other disk substrate has an information recording layer. Does not have a recording layer. Its structure is as shown in FIG. Numeral 1 in FIG. 1 denotes a disk substrate having a thickness of 0.6 mm having an information recording layer, numeral 2 denotes an information recording layer made of a thin film transparent to ultraviolet light and visible light, and numeral 3 denotes an information recording layer transparent to ultraviolet light. The disk substrate without the numeral, numeral 4 indicates an adhesive layer (adhesive composed of an ultraviolet curable composition).

In the following description, the disk substrate having no information recording layer is called a "dummy disk substrate" and the disk substrate having an information recording layer is called an "information disk substrate".

In the DVD-5 disc, it is necessary to print some kind of data on the surface of the dummy disc substrate, print the contents of the program recorded on the disc, or image the contents of the recording, and display the manufacturer and the like. Usually, when printing is performed on the surface of the substrate, there is a problem that the printed surface is easily deteriorated due to dirt or scratches.

[0008] Alternatively, in order to give the product a more luxurious feel, this product, which emphasizes the image of the product, employs a manufacturing method in which the back side of the dummy disk substrate is printed in advance and then bonded to the information substrate. May be used. In this way, the printed surface does not come directly to the surface, so that it is not stained or damaged, and the printed matter is viewed through the transparent dummy disk substrate. Gives a sense of luxury. In the following description, such a disk substrate will be referred to as a “preprint substrate”.

Further, as another method of drawing a pattern or a character on the back side of the dummy disk substrate, a pit not used for information recording is formed in the same manner as provided on an information recording layer, instead of using a normal printing ink. There is also a method of using a group (referred to as a “dummy pit group” in the following description to distinguish it from a normal pit group used for information recording) and describing the size of the dummy pit group and the density. In such a dummy disk substrate, at the time of molding the substrate, patterns and characters are created on the substrate surface by using the size and density of pit groups, and on top of that, as in the case of a normal information disk substrate, ultraviolet transmittance and visible light are formed. By providing a light-reflective thin film, for example, a sputtered layer made of aluminum, a technique is adopted in which the patterns and characters are clearly brought out. In the following description, such a disk substrate is referred to as a "pit image substrate".
I will call it.

FIG. 2 is a diagram showing the structure of a DVD-5 when a preprint substrate or a pit image substrate is used as a dummy disk substrate. Number 5 in FIG.
Represents a printing layer applied to the back surface (adhesion surface) of the dummy disk substrate or a layer in which a pattern or the like is drawn by a dummy pit group.

When the above-mentioned preprinted substrate or pit image substrate is bonded to the information disk substrate, the ultraviolet-curable composition is used as an adhesive, and ultraviolet rays are repeatedly applied from both sides of the disk in a flash-like manner to cure and adhere. The design or characters of the printed or pit image provided on the dummy disk substrate are exposed on the information recording layer side, not only impairing the intended luxury, but also impairing the information reliability in severe cases. There was a problem. In the following description, such a phenomenon that a design or a character appears on the information recording layer side will be referred to as “set-off”. The set-off is very similar to a feeling that, for example, when a 10-yen coin is wrapped in aluminum foil and pressed with a finger from above, the irregularities of the 10-yen coin are modeled by the aluminum foil and appear embossed.

[0012]

SUMMARY OF THE INVENTION In view of the above circumstances, the present invention relates to a method of curing and bonding by repeatedly irradiating ultraviolet rays from both sides of a disk using an ultraviolet curable composition as an adhesive. It is an object of the present invention to provide a method and an apparatus for bonding a disk with high information reliability by suppressing set-off when manufacturing a DVD-5 disk using a pit image substrate as a dummy disk substrate.

[0013]

Means for Solving the Problems The present inventors have made intensive studies to solve the above-mentioned problems, and found that one of the two information recording layers has an ultraviolet-transmissive and visible-light-reflective information recording layer on an ultraviolet-transparent substrate. The information disk substrate having a, the other is a dummy disk substrate having an ultraviolet-transparent printed layer on the ultraviolet-transparent substrate, or a ultraviolet-transparent and visible light-reflective thin film on the ultraviolet-transparent substrate Have
A dummy disk substrate having an ultraviolet-permeable and visible-light-reflective thin film in which a dummy pit group not used for information recording is provided in the thin film and a pattern is drawn by shading and size of the dummy pit group, wherein the two disks Using a UV-curable composition as an adhesive for the substrate, the information recording surface of the information disk substrate and the printed surface of the dummy disk substrate or a surface on which a pattern is drawn are stuck together,
A method of bonding the information disk substrate and the dummy disk substrate by repeatedly irradiating ultraviolet rays from both outer sides of one bonded disk in a flash manner to cure the adhesive, wherein the flash irradiation is performed. At any time between the time when the flash irradiation is started and the time when the flash irradiation is completed, the value obtained by integrating the flash irradiation energy on the disk substrate surface is smaller than the dummy disk when viewed from the outside of the information disk substrate. It has been found that the flashover is suppressed so that the flashover is always larger than that from the outside of the substrate side, and that the adhesive curing can be completed, and the present invention has been accomplished.

That is, the present invention provides the following invention. 1. One of the two is an information disk substrate having an ultraviolet-transmissive and visible light-reflective information recording layer on an ultraviolet-transparent substrate, and the other is a dummy having an ultraviolet-transmissive printed layer on the ultraviolet-transparent substrate. Disc board
Or, having a UV-transmissive and visible light-reflective thin film on an ultraviolet-transparent substrate, providing a dummy pit group not for information recording in the thin film, and drawing a pattern by shading and size of the dummy pit group A dummy disk substrate having a thin film capable of transmitting ultraviolet light and reflecting visible light, wherein the two disk substrates use an ultraviolet-curable composition as an adhesive, and the information recording surface of the information disk substrate and the dummy disk substrate The information disc is hardened by repeatedly irradiating ultraviolet rays from both outer sides of one of the discs that are stuck to each other so as to harden the adhesive so that the printed face or the face on which the pattern is drawn faces each other. A method of bonding a substrate and the dummy disk substrate, from a time when the flash irradiation starts to a time when the flash irradiation ends. At any time during the period, the value obtained by integrating the flash irradiation energy on the disk substrate surface is always larger on the outer side of the information disk substrate than on the outer side of the dummy disk substrate. A method of bonding the disks (hereinafter, referred to as a first invention) characterized by irradiating a flash as described above.

2. One of the two is an information disk substrate having an ultraviolet-transmissive and visible light-reflective information recording layer on an ultraviolet-transparent substrate, and the other is a dummy having an ultraviolet-transmissive printed layer on the ultraviolet-transparent substrate. It is a disk substrate, or has a UV-transmissive and visible-light-reflective thin film on a UV-transmissive substrate, and provides a dummy pit group that is not used for information recording in the thin film. A dummy disk substrate having an ultraviolet-transparent and visible-light reflective thin film in which a pattern is drawn by size, wherein the two disk substrates are recorded on the information disk substrate by using an ultraviolet-curable composition as an adhesive. And the printed surface of the dummy disk substrate or the surface on which the pattern is drawn are attached to each other so as to face each other. An apparatus for bonding the information disk substrate and the dummy disk substrate by irradiating the adhesive by flashing at a constant repetition rate to cure the adhesive, wherein at least one flash is provided on both outer sides of the disk. A flash irradiation from the outside of the information disk substrate side, and a flash irradiation from the outside of the dummy disk substrate side is performed prior to the flash irradiation from the outside of the information disk substrate side. The above-mentioned two switching means are configured so as to perform the above-mentioned operations, wherein the disk bonding apparatus (hereinafter, referred to as a second invention).

In the present invention, one of the two disk substrates used for bonding is an information disk substrate having an ultraviolet-transmissive and visible-light reflective information recording layer on an ultraviolet-transparent substrate.

The other is one of the following. 1. A dummy disk substrate having an ultraviolet-transmissive printed layer on an ultraviolet-transparent substrate. 2. An ultraviolet-ray having a thin film that is ultraviolet-transmissive and visible light-reflective on an ultraviolet-transmissive substrate, and a dummy pit group not used for information recording is provided on the thin film, and a pattern is drawn by shading and size of the dummy pit group. A dummy disk substrate having a transparent and visible light reflective thin film.

In the present invention, the pattern formed by shading and the size of the dummy pit group not used for information recording is called a pit image.

The thickness of the two disc substrates selected to be bonded to the former information disc substrate and the latter dummy disc substrate is not limited, but in the case of DVD, both of them are usually 0.6 mm. is there. In the present invention, since it is necessary to cure the adhesive described later, any layer provided between the adhesive and the ultraviolet-permeable substrate must be ultraviolet-permeable. For example, when the thin film provided on the information disk substrate, the printed layer provided on the dummy disk substrate, or the thin film provided with the pit image is sufficiently thick, it is considered that the ultraviolet ray is not substantially transmitted. In this case, the present invention cannot be applied.

As the UV-transmitting substrate, any of known and commonly used materials can be used, and examples thereof include heat-resistant thermoplastic synthetic resins such as acryl, polycarbonate, and amorphous polyolefin. The information recording layer is formed by forming irregularities corresponding to recorded information on one surface of the substrate, and laminating an ultraviolet-transparent and visible-light reflective thin film thereon.

The UV-transparent and visible-light-reflective thin film is preferably a thin film capable of accurately reflecting the visible light employed for reading recorded information by reflecting the visible light at a high rate. A thin film that reflects visible light at a high rate generally reflects ultraviolet rays at a high rate. The thin film that does not transmit ultraviolet light at all cannot be applied to the present invention. Examples of the ultraviolet-transparent and visible-light-reflective thin film include metals that transmit ultraviolet light and reflect visible light, such as aluminum, nickel, gold, and alloys. Usually, the metal used as the thin film has a visible light reflectance of 80 to 100% and a transmittance of more than 0 over the entire ultraviolet wavelength range of 10 to 10%.
%, Preferably more than 0 and less than 3%. The thickness of the thin film is usually from 200 to 600 angstroms.

The disk substrate used in the present invention is obtained by casting the material to be the substrate on a stamper having a predetermined size, shape and thickness, for example, engraved with grooves corresponding to reproduction information such as sound and video. After that, it can be obtained by laminating a thin film that transmits ultraviolet light and reflects visible light. This lamination can be generally performed by depositing or sputtering the metal to a predetermined thickness on the groove surface of the substrate provided with the groove. Thus, an information recording layer in which the groove and the thin film are integrated is formed.

As the adhesive for laminating the disks, known and commonly used ultraviolet-curable compositions can be used. This UV curable composition may be referred to in the art as an ultraviolet curable resin. As the ultraviolet curable composition, an ultraviolet curable composition containing a photopolymerization initiator is desirable in order to further improve the ultraviolet curability. It is preferable that the photoinitiator be cured and adhered with high efficiency and certainty so that the absorption wavelength of the photoinitiator and the wavelength of the irradiation ultraviolet ray described later overlap at least.

In preparing the ultraviolet curable composition, a monofunctional (meth) acrylate and a polyfunctional (meth) acrylate can be used as a polymerizable monomer component. Each of these can be used alone or in combination of two or more. In consideration of curing shrinkage and adhesiveness, it is preferable to use a monofunctional (meth) acrylate as a main component and a polyfunctional (meth) acrylate in combination.

Examples of the monofunctional (meth) acrylate include (meth) acrylic acid alkyl esters having an alkyl group having 1 to 20 carbon atoms which may be linear or branched.
Examples include an aromatic vinyl monomer, an aromatic ring-containing (meth) acrylate, an aliphatic ring-containing (meth) acrylate, and a heterocycle-containing (meth) acrylate.

Examples of the polyfunctional (meth) acrylate include oligomers such as polyether poly (meth) acrylate, polyester poly (meth) acrylate, polyurethane poly (meth) acrylate, epoxy poly (meth) acrylate, and alkane polyol poly (meth) acrylate. A) acrylate, polyalkylene glycol di (meth) acrylate, trimethylolpropane poly (meth) acrylate, pentaerythritol poly (meth) acrylate, dipentaerythritol poly (meth) acrylate, and the like.

These include, for example, (meth) acrylic acid,
A sulfonic acid group-containing monomer, a phosphoric acid group-containing monomer, a hydroxyl group-containing monomer, a tertiary amino group-containing monomer, and the like can be used in combination.

As the curable component of the ultraviolet curable composition, as described above, the weight ratio is appropriately adjusted in consideration of, for example, the coating method, the thickness of the adhesive layer, the adhesive strength, the corrosiveness, and the durability. It can be adjusted and prepared.

The photopolymerization initiator may be any one as long as it generates a radical by light and the radical efficiently reacts with the (meth) acrylate constituting the composition. There are a type in which a molecule is cleaved to generate a radical, and a type in which a compound is used in combination such as a combination of an aromatic ketone and a hydrogen donor.

Examples of the former include benzoin ethyl ether, benzoin isobutyl ether, benzyl dimethyl ketal, 1-hydroxycyclohexyl phenyl ketone, 2-hydroxy-2-methyl-1-phenyl-propan-1-one, , 6-Trimethylbenzoyldiphenylphosphine oxide, 1- (4-isopropylphenyl) -2-hydroxy-2-methylpropan-1-one and 2-methyl-1- (4-methylthiophenyl) -2-morpholinopropane -1-one and the like.

The aromatic ketones of the latter examples include benzophenone, 4-phenylbenzophenone, isophthalophenone, 4-benzoyl-4'-methyl-diphenylsulfide, 2,4-diethylthioxanthone, 2-isopropylthioxanthone and 2-isopropylthioxanthone. Chlorothioxanthone and the like can be mentioned, and as the hydrogen donor combined therewith, for example, a mercapto compound and an amine compound can be mentioned, but an amine compound is generally preferable.

Examples of the amine compound include triethylamine, methyldiethanolamine, triethanolamine, diethylaminoethyl (meth) acrylate, p-dimethylaminoacetophenone, ethyl p-dimethylaminobenzoate, iso-aluminum p-dimethylaminobenzoate, , N-dimethylbenzylamine and 4,
4'-bis (diethylamino) benzophenone and the like.

The temperature of the UV-curable composition is from room temperature to 40 ° C.
It is desirable to use a liquid. It is preferable not to use a solvent, and even if it is used, it is desirable to keep it as small as possible. When the composition is applied by a spin coater, the viscosity is desirably adjusted to about 300 to 600 cps so that a coating film having a uniform thickness is easily obtained.

A disc made by laminating two disc substrates is susceptible to deformation and distortion of the individual substrates, and has a uniform thickness as a whole of the adhesive layer and the finished disc after lamination. Is difficult to obtain. To solve this problem, for example, each disk substrate is held by using a disk substrate holding member having a deaeration adsorption element having excellent surface roughness and surface accuracy.
The deformation and distortion inherent in the plastic disk substrate is forcibly absorbed by the holding member, and the disk substrate is so formed as to have a higher level of surface accuracy than the surface accuracy that the disk substrate has conventionally had. If the ultraviolet curable composition as an adhesive is filled in the adhesive layer space between the two disk substrates in a corrected state, even if it is not irradiated with ultraviolet light, the state is corrected by the temporary adhesive force. Can last for a little time. Thus, by releasing the holding of the disk substrate and irradiating the ultraviolet rays as early as possible without taking time as much as possible, the thickness of the finished disk after bonding can be made constant.

By using a disk substrate holding member having a deaerating and adsorbing element which is transparent to ultraviolet light and is excellent in surface roughness and surface accuracy, the disk substrate holding member can be used without releasing the holding member. The adhesive can be ultraviolet-cured while maintaining the precise precision surface accuracy state when holding the substrate, and the thickness of the finished disc after bonding is more constant. It is easier to obtain.

In order to precisely apply the ultraviolet curable composition in a fixed amount, for example, a function of compensating a variation in the discharge amount due to a difference in water head in a composition (resin) tank, or a vacuum automatic apparatus for preventing liquid dripping and air bubble mixing. It is possible to use a liquid precise metering device with a correction function. As such a liquid precise metering device, there is, for example, one manufactured by Musashi Engineering Co., Ltd. or one manufactured by EFD in the United States.

In the present invention, the adhesive made of the ultraviolet-curable composition is bonded so that the information recording surface of one substrate faces the printed surface or pit image formed surface of the other substrate. However, it can be applied to one or both of the information recording surface of one substrate and the printed surface or pit image formed surface of the other substrate.

The UV-curable composition may be applied to the entire surface of the disk substrate to which adhesion is required (hereinafter, referred to as an adhesive surface), or may be applied to a part of the adhesive surface and then applied. It may be deployed on the entire surface. A ring-shaped adhesive is applied to the required adhesive surface of the disk substrate so that it is concentric with the center axis of the disk, and one disk substrate is fixed on a flat surface with the adhesive surface facing up, and the other disk substrate is attached to both surfaces. There is also a method in which the adhesive applied in the form of a ring is gradually developed and enlarged over the entire surface while being overlapped and pressed so that the center axes of the disk substrates are aligned, and then the ultraviolet rays are irradiated. In this case, a relationship of “adhesive volume / surface area of the adhesive surface required = thickness of the adhesive layer” is established. The thickness of the adhesive layer after curing can be determined from the above relationship and the cure shrinkage of the adhesive.

When the ultraviolet curable composition is applied by the liquid precise metering apparatus, the viscosity of the composition (resin) should be adjusted to about 3000 cps to 20,000 cps, even if the disk substrate is turned upside down after the ejection. During the predetermined time, the shape can be appropriately maintained, and the composition applied in a ring shape before overlapping is not spread more than necessary, but it is difficult to spread as there is a part that is not applied. It is preferable because an adhesive layer having a uniform thickness can be easily obtained. It is preferable that the shape of the ejection of the adhesive on the surface requiring adhesion of the disk be a ring shape.

The adhesive can be applied in a ring shape so as to be concentric with the center of the disk only on the required adhesive surface of one disk substrate, or on the required adhesive surface of each of the two disk substrates. Alternatively, it can be applied in a ring shape so as to be concentric with the center of the disk.

There is a concern that bubbles may be generated when the ultraviolet curable composition is spread over the entire surface of the disk substrate to be bonded. However, the adhesive composed of the composition applied in a ring shape may be completely bonded to each other. By using the means for intermittently descending by a minute distance until contact is made over the circumference, the generation of the bubbles can be almost eliminated.

The two disk substrates to be bonded are
A disk substrate holding member having a deaeration / adsorption element having a small surface roughness and excellent surface accuracy, and holding the surfaces opposite to the required bonding surface of the disk substrate to correct the flatness, thereby bonding the substrates. The effect is achieved that the thickness of the finished disk can be made constant over the entire disk.

As the material for the disk substrate holding member, known materials can be used. For example, metals such as stainless steel, aluminum and titanium, plastics such as polyphenylene sulfide and aromatic polyimide, and glass can be used. . When a material having no specific surface roughness and surface accuracy is used, the surface can be used after being mirror-finished. Regardless of whether the above-mentioned material is used or the disk substrate holding member is used, a material having ultraviolet transmittance is more preferable than a material having no ultraviolet transmittance.

The smaller the absolute value of the surface roughness and surface accuracy of the disk substrate holding member, the better. As the material, for example, the surface roughness Rmax in JISB0601 is used.
In order to obtain a disk substrate holding member of about 1 μm and surface accuracy of about 7λ (λ = 5460 Å),
In that it can be easily processed to the surface roughness and surface accuracy described above,
It is desirable to use a metal or glass material. Among them, quartz glass has a surface roughness Rmax according to JIS B0601.
It is particularly preferable because it can be mirror-finished to ≦ 0.05 μm and surface accuracy ≦ λ (λ = 5460 Å), and can be a holding member which is much more excellent in surface roughness and surface accuracy than metal.

The method of laminating the two disk substrates before bonding using the disk substrate holding member is not particularly limited. For example, the adhesive surfaces of the two disk substrates are opposed to each other, and the lower disk substrate is It is also possible to lower the upper disk substrate and press it without moving, or conversely, raise and press the lower disk substrate without moving the upper disk substrate. Can also. Alternatively, the lower disk substrate may be raised and the lower disk substrate may be lowered and pressed.

If the disk substrate holding member is not transparent to ultraviolet rays, it is necessary to release the holding of the disk and evacuate the optical path between the ultraviolet lamp light source and the disk before performing the ultraviolet irradiation. On the other hand, when the disk substrate holding member is transparent to ultraviolet light, since ultraviolet irradiation can be performed through the holding member, the holding of the disk is released, and the holding member is placed on the optical path between the ultraviolet lamp light source and the disk. There is no need to evacuate. This not only significantly improves the bonding workability, but also has an advantage that a mechanism for retracting the holding member from the optical path is not required.

In the case where the disk substrate is extremely warped or deformed, as described above, even if the disk substrate can be forcibly corrected by the disk substrate holding member, the holding by the member is released and all or all of the disk substrate is held. If a part of the disc is retracted, the two hard-to-cure, closely-spaced disc substrates themselves are subject to the force of restoring to their original condition, making it difficult to cure and adhere in a straightened state. Becomes

Therefore, when using a disk substrate holding member that does not transmit ultraviolet light, release the holding by the member and immediately irradiate the ultraviolet light without leaving the device for a long time. It is effective means to use a high-viscosity-adhesive ultraviolet-curable composition having a high adhesive strength to the surface requiring adhesion, or to use these two means in combination. On the other hand, in the case of using a disk substrate holding member that transmits ultraviolet light, it is unnecessary to release the holding by the member itself, so there is no need to consider the time from the superposition to the irradiation of ultraviolet light. Good.

Examples of the degassing / adsorbing element include a flat disk substrate holding member provided with a plurality of holes or grooves on at least one side, and a degassing pump. In this case, one surface of the disk substrate can be suctioned by the deaeration pump through the holes or grooves to reduce the pressure, and the disk substrate can be held and fixed by the suction force (adsorption force). It is preferable to connect the above-mentioned holes and grooves and suction the air from one deaeration suction port because the device is simpler than deaeration and suction of the holes and grooves individually. In holding and fixing the disk substrate, the force of fixing the disk substrate increases as the degree of pressure reduction increases. Then, after completion of the lamination of the disks, if the air suction is released and the suction holes and the grooves are brought to a normal pressure, the disk substrate can be released from the holding member and separated.

In the present invention, the information recording surface and the printed surface or the surface on which the pit image is formed are brought into opposing contact via the uncured adhesive to form a single disk, and ultraviolet light is applied from both outer sides thereof. Are repeatedly flashed to cure and bond the two. Here, each of the ultraviolet transparent substrates constituting the information disk substrate and the dummy disk substrate before bonding is located outside.

The ultraviolet light source used in the present invention has a function of flashing and emitting light repeatedly. It is desirable that the lamp to be used has a high durability such as a xenon flash lamp that can withstand repeated light emission.

FIG. 3 shows a flash discharge mechanism for flashing the lamp. Numeral 6 in FIG. 3 is a capacitor having a capacitance C for accumulating electric charge, numeral 7 is an air-core coil for suppressing a peak value of current at the time of discharging, numeral 8 is a flash discharge lamp (xenon flash lamp), Numeral 9 indicates an auxiliary electrode obtained by winding a wire around the flash discharge lamp several times, numeral 10 indicates a high-voltage pulse generating circuit, and numeral 11 indicates a trigger signal input terminal.

As means for charging the capacitor of number 6, for example, a DC high-voltage power supply having an output voltage V (unit: volt) set to a predetermined value and a charging current suppressing resistor are connected in series. Element (not shown)
Can be used. In order to discharge the electric charge accumulated in the condenser of the numeral 6 to the xenon flash lamp of the numeral 8, the numeral 1 is placed between the auxiliary electrode of the numeral 9 and one electrode of the lamp of the numeral 8.
It can be performed by applying a high-voltage pulse from a 0 high-voltage pulse generation circuit. The high-voltage pulse generating circuit of Numeral 10 applies a control signal of, for example, 5 volts from the trigger signal input terminal of Numeral 11 to the auxiliary electrode of Numeral 9, which is the output side of the circuit, for a few kilometers of peak values. It has a mechanism for outputting a high-voltage pulse of several tens of kilovolts.

In this manner, by applying a control signal from the trigger signal input terminal of numeral 11 in FIG. 3, a high-voltage pulse is generated between the auxiliary electrode wound around the lamp outer wall of numeral 9 and the negative electrode of the lamp. In addition, the gas containing xenon sealed inside the lamp of the numeral 8 causes dielectric breakdown for a moment. This dielectric breakdown is triggered, and the electric charge stored in the capacitor indicated by numeral 6 is released at once in the lamp during a very short time t, and at this time, a strong flash is emitted. At this time, the flash irradiation energy E is "E = C
It is obtained as V ^2/2 ".

The discharge mechanism shown in FIG.
~ 5 sets each consisting of two disc substrates bonded together
Lamps are provided at predetermined intervals so that the UV irradiation intensity is substantially constant over the entire surface of the disk, and the discharge mechanisms provided in 4 to 5 sets are shown in FIG.
If a control signal is simultaneously supplied to all the discharge mechanisms from the terminal corresponding to the numeral 11, the flash irradiation with uniform light intensity over the entire surface of the disk can be performed.

The flash irradiation energy is from μsec to m
Since the electric potential is released during a very short time on the order of seconds, the potential difference between the two electrodes of the lamp rapidly decreases with the start of discharge, and the discharge itself ends instantaneously.

According to the present invention, at any time between the time when the flash irradiation is started and the time when the flash irradiation is finished, the value obtained by integrating the flash irradiation energy on the disk substrate surface is equal to the information disk substrate side. The flash irradiation is performed such that the area from the outside of the dummy disk substrate is always larger than the area from the outside of the dummy disk substrate.

When there is no factor for attenuating ultraviolet light between the ultraviolet light source and the information disk substrate (optical path) and between the ultraviolet light source and the dummy disk substrate (optical path), light is emitted from each ultraviolet light source. Under the condition that each flash irradiation energy E is the same energy amount and both optical path distances are the same, the amount of energy reaching each disk substrate surface is the same. Of course, if the optical attenuation rate in each optical path is the same, as the optical path distance increases, the amount of energy on the irradiated object side reaching each disk substrate surface becomes more than the absolute value of the flash irradiation energy E on the light emitting side emitted from the light source. Become smaller.

In the case where there is no factor for attenuating the ultraviolet rays between the respective optical paths as described above, of the energy E emitted from each ultraviolet light source, the energy reaching the disk substrate surface is arithmetically calculated based on the optical attenuation rate and the optical path distance. Can be calculated. Therefore, in the case where the light attenuation rate and the light path distance between the light paths are large, it is sufficient to previously set each flash irradiation energy E emitted from each ultraviolet light source to a larger value in consideration of energy attenuation (dimming).

In the present invention, the integrated value of the flash irradiation energy on the disk substrate surface is always larger on the outer side of the information disk substrate than on the outer side of the dummy disk substrate. In irradiating the flash light, if there is no factor for attenuating the ultraviolet light between the respective optical paths, only the adjustment of each flash irradiation energy E emitted from each ultraviolet light source as described above,
Can be controlled.

In addition, by consciously providing a factor for attenuating ultraviolet rays between the respective optical paths, the integrated value of the flash irradiation energy on the disk substrate surface is closer to the dummy disk than from the information disk substrate side. For example, the following means can be used to irradiate the flash light so that it is always larger than that from the outside of the substrate side.

The energy of the light irradiated from the information disk substrate side and the energy of the light irradiated from the dummy disk substrate side are made the same, and the flash type irradiation means on the dummy disk substrate side and the dummy disk substrate are provided with an optical path. A method in which flash irradiation is performed by disposing an optical filter that diminishes ultraviolet light to make a difference in the integrated value of flash irradiation energy on the disk substrate surface.

The energy of light emitted from the information disk substrate side and the energy of light emitted from the dummy disk substrate side are made the same, and the (optical path) distance between the flash irradiation means on the information disk substrate side and the information disk substrate; Flash light irradiation is performed so as to provide a difference in the (light path) distance between the flash light irradiation means on the dummy disk substrate side and the information disk substrate,
A method to make a difference in the integrated value of flash irradiation energy on the disk substrate surface.

The above methods and the above methods may be employed alone or in combination. Further, depending on the case, the above can be carried out by making the energy of light emitted from the information disk substrate side and the energy of light emitted from the dummy disk substrate side different.

However, without providing an optical filter for attenuating ultraviolet rays between the optical paths or providing a factor for attenuating ultraviolet rays between the optical paths such as providing a difference in the distance between the optical paths, the light emitted from each ultraviolet light source is not provided. The method of controlling only the amount of each energy of the light to be obtained is more preferable from the viewpoint of the input electric energy than the method of performing the control without controlling the energy.

As a mechanism for causing the lamp to emit light repeatedly in a flashing manner, for example, there is the following mechanism. In the discharging accompanied by the flash, charging of the capacitor of numeral 6 is started from the DC voltage power supply side almost simultaneously with the end of the discharging. The time required for charging is related to a time constant τ obtained by the product of the capacitance C (unit is Farad) of the capacitor of number 6 and the charging current suppressing resistance (unit is ohm). The time constant τ
And the discharge time t is generally τ≫t.

When the high-voltage pulse is applied again when the charge accumulation in the capacitor of the numeral 6 is saturated and the dischargeable level is reached again, a second flash is emitted. The flash type repetitive light emission can be performed by repeating the above operation.

In performing flash irradiation with ultraviolet light, if the light from the light source lamp contains visible light or infrared light unnecessary for curing the ultraviolet curable composition, the unnecessary light is blocked. Then, it is preferable that only the ultraviolet ray is irradiated. In this way, the unnecessary light can be prevented from being irradiated to the surface of the disk substrate, and the heat can prevent the disk itself from being warped or deformed or the recorded information from being degraded. Can be.

In selectively blocking the unnecessary light from the light emitted from the light source lamp, an infrared cutoff filter or the like can be generally used.

According to the knowledge of the present inventors, even if the discharge energy per discharge is the same, if the peak value and the time width of the discharge current are changed, the light intensity and the spectrum distribution emitted from the light source lamp are changed. It was also found that the curability of the ultraviolet curable composition having the same composition changed. On the other hand, in a metal thin film of aluminum, nickel, or the like, the transmitted light intensity and spectral distribution differ depending on the material and thickness.

In an apparatus for irradiating ultraviolet light with a flash, in order to be able to bond various kinds of disks under the same process conditions, the thickness of the ultraviolet-transmitting and visible-light reflecting thin film used for the disk substrate is required. It is preferable that the apparatus has a mechanism capable of changing circuit constants such as a charging voltage, a capacitor capacity, and an inductance of a discharging circuit according to the light transmission characteristics. In this manner, with respect to various disks, the peak value and the time width of the discharge current are appropriately adjusted by one irradiation device, and the adhesive can be efficiently cured by the ultraviolet irradiation.

In the flash irradiation, strong ultraviolet rays are radiated from a light source lamp at the time of light emission, and light in an infrared region where heat is easily transmitted to an object is also irradiated toward the disk substrate at a considerable rate. Even with such a strong flash, if it is made of a material such as polycarbonate, which easily transmits light, there is almost no deformation due to heat or damage to the surface.

However, when the substrate is provided with a thin film made of a metal such as aluminum having low light transmittance,
Most of the light energy during the flash irradiation is reflected at the interface and returned to the light source lamp side. At this time, if the peak power of the flash is too strong or the distance between the lamp and the disk is too short, the metal The thin film may be damaged and discolored.

Therefore, it is necessary to appropriately adjust the discharge current waveform and the distance between the lamp and the disk so that the reliability of the information carved in the pit group of the information recording layer is not impaired by the flash irradiation. . The peak power of the flash is reduced by either lowering the charging voltage of the capacitor of number 6 or increasing the inductance of the air-core coil of number 7 to a larger value. Can be adjusted.

In practicing the first invention, the flash irradiation from both outer sides of the bonded single disk is synchronous, and the repetition rate of the flash irradiation from both outer sides is constant. When the flash irradiation energy on the disk substrate surface per flash from the outside of the information recording disk substrate side and from the outside of the dummy disk substrate side is E1 and E2, respectively, it is preferable that E1> E2.

In carrying out the method of the first invention,
Preferably, the device of the second invention is used. The apparatus according to the second invention is characterized in that at least one flash type ultraviolet irradiating means is provided on both outer sides of the disk, and two switching means which are opened and closed with a time difference allowing flash of the flash type irradiating means; Control means for controlling the two switching means so that the flash irradiation from the outside of the disk substrate is performed prior to the flash irradiation from the outside of the dummy disk substrate. As described above, the means for irradiating ultraviolet light in a flash manner can be constituted by, for example, the flash discharge mechanism and the ultraviolet light source lamp. In carrying out the second invention, it is preferable that one to six ultraviolet light source lamps are provided on each of the outer sides of the information disk substrate and the dummy disk substrate to be bonded.

The ultraviolet irradiation means is controlled by two switching means which are opened and closed with a time difference.
The switching means is not limited to being able to irradiate ultraviolet light in a flashing manner simply with a time difference, and the flash light from the outside on the information disk substrate side is not necessarily on the outside on the dummy disk substrate side. So that it takes precedence over time, rather than flash light from
A closing operation (ON) must be performed. By doing so, as an example, for example, in the case where irradiation is simultaneously ended with the same irradiation energy amount from both outer sides in each case, as in the first invention, the flash irradiation is started from the time when the flash irradiation is started. At any time before the end time, the value obtained by integrating the flash irradiation energy on the disk substrate surface is greater from outside the information disk substrate side than from the dummy disk substrate side. Can always be increased.

FIGS. 4A and 4B show two examples having a mechanism embodying the device of the second invention. Numeral 12 in FIG. 4 denotes a diode, and numeral 13 denotes a control signal generator for giving a light emission command at a constant repetition rate. Symbol L
Reference numeral 1 and the symbol SW1 respectively represent a light source lamp provided outside the information disk substrate and a switch (switch means) for permitting the light source lamp to emit light. The symbol L2 and the symbol SW2 respectively represent a light source lamp provided outside the dummy disk substrate side and a switch (switch means) for permitting the light source lamp to emit light.

In either of the circuit configurations shown in FIGS. 4A and 4B, the flash irradiation from the outside on the information disk substrate side is made longer than the flash irradiation from the outside on the dummy disk substrate side. In order to perform this first, the switch of symbol SW1 is first closed (turned on) first, and after the elapse of a predetermined time T1 (corresponding to the “light emission time difference” from both outer sides), this time, SW2 is turned on. Are closed, and after a lapse of a predetermined time T2, both switches SW1 and SW2 are simultaneously opened (OFF
Is done). To perform these switching operations automatically, a sequencer having two or more switching means is used to connect the sequencer and the switch circuit of FIG. 4 in a predetermined manner, and the above-described operation procedure is programmed. This is made possible by:

Regardless of whether a preprinted substrate or a pit image substrate is used as the dummy disk substrate, the light emission time difference T1 from both outer sides may be appropriately adjusted. When the thickness of the object layer is taken as a thickness, the time difference is set so that the closer the surface on the information recording layer side is, the higher the degree of hardness and the higher the hardness than the farther side of the surface on the information recording layer side. May be provided so that the light is repeatedly emitted in a flashing manner. The time difference T1 is determined by the curability of the ultraviolet curable composition,
It is desirable to adjust the ultraviolet transmittance of the visible light reflective thin film provided on the information disk substrate, or the ultraviolet transmittance of a print layer or a pit image layer provided on the dummy disk substrate.

In the above-described irradiation method, the flash irradiation from the outside of the information disk substrate side is performed at least once before the flash irradiation from the outside of the dummy disk substrate side, and then at least from the dummy disk substrate side. 1
When the flash irradiation is performed more than once, the flash irradiation may be performed simultaneously from both outer sides of one laminated disk.

In this case, the repetition rate of flash irradiation from both outer sides of the one disk before curing, which has been bonded, is constant, and N1 and N2 are both natural numbers.
The number of times of flash irradiation from the outside of the information disc substrate side is N1,
Assuming that the number of times of flash light irradiation from the outside of the other dummy disk substrate side is N2, the magnitude relationship between N1 and N2 is N1>
It is preferable to perform the treatment so as to be N2.

In addition to satisfying the above relationship, if the flash irradiation from each side is performed synchronously at a constant repetition rate so that the last flash irradiation from each side is simultaneous,
The disk can be exposed to more ultraviolet irradiation energy in a shorter time than when the flash irradiation repetition rate is not constant and the flash irradiation from both outer sides is performed asynchronously. From the point of view and from the viewpoint of manufacturing the bonding apparatus of the present invention, it is desirable in that the apparatus structure can be simplified.

Note that the present inventors applied the flash irradiation at the time of bonding the two disk substrates at any time between the time when the flash irradiation was started and the time when the flash irradiation was terminated. The flash irradiation is performed such that the integrated value of the flash irradiation energy on the substrate surface is always larger from the outside of the information disk substrate than from the outside of the dummy disk substrate. We consider the reason why the shift is suppressed as follows.

That is, regardless of whether a pre-printed or pit image substrate is used as the dummy disk substrate, the ultraviolet light transmission on the disk is affected by the design, pattern, characters, etc. drawn by the printing ink or the density of the pit group. Places can be considered quite different from place to place. Of the printed colors, for example, a bright and whitish portion generally tends to have better ultraviolet transmittance, and conversely, a darker portion tends to have poor ultraviolet transmittance. In the pit image substrate, it is expected that the inclined portions forming the pits diffusely reflect the ultraviolet light, and the ultraviolet light transmittance at that portion is considerably reduced locally.

As described above, in the case of the pre-printed substrate and the pit image substrate, even if they are in the same substrate, since the ultraviolet transmittance is locally different depending on the place, the ultraviolet curable composition Is used as an adhesive, and when ultraviolet rays are repeatedly and simultaneously irradiated from both sides of the disc, which is made by bonding the information substrate and the dummy disk substrate, from the outer side of the adhesive layer, the interface between the information recording layer side The curing reaction that proceeds is considered to proceed uniformly over the entire disc area in the direction of the adhesive layer interface on the dummy disk substrate side, whereas the curing reaction that proceeds from the interface on the other dummy disk substrate side Is considered to proceed while being directly affected by the level of the ultraviolet transmittance.

As a result, the adhesive layer in the portion having a high ultraviolet transmittance is harder, while the adhesive layer in the portion having a low ultraviolet transmittance remains relatively soft, and the interface side of the other information disk substrate From the cured layer that has been uniformly cured. It is considered that set-off occurs due to a difference in internal stress between a hard part and a soft part because the bonding is performed in a state where the entire adhesive surface is not uniform in hardness.

Accordingly, the suppression of such set-off is achieved by curing the adhesive layer by ultraviolet light irradiation from the information recording layer side by ultraviolet light irradiation from the preprint substrate side or the pit image substrate side. It can be considered that by proceeding before the curing that occurs in the above, a relatively thick cured layer was formed on the side near the information recording layer, and this was achieved.

The discs bonded together as described above become excellent in quality without deteriorating the quality image and sense of quality due to set-off, and without impairing the information reliability. This disc can be scanned and irradiated with visible light with a semiconductor laser while rotating it, for example, to reproduce the information on the information recording surface, thereby converting it into a sound or video signal and providing it to the viewer for viewing. it can.

[0090]

[Action]

(1) A preprinted substrate or a pit image substrate is used as a dummy disk substrate, an ultraviolet curable composition is used as an adhesive, and the disk is bonded to a disk substrate having an information recording layer. In the case of repeatedly irradiating ultraviolet rays from the outside in a flashing manner, the energy (unit) of the flash irradiation on the disk substrate surface may be any time between the time when the flash irradiation is started and the time when the flash irradiation is ended. : J), by adopting a method of irradiating a flash so that the value from the outside of the information disk substrate is always larger than the value from the outside of the dummy disk substrate. The adhesive layer formed by the ultraviolet-curable composition applied to a thickness of about 40 μm, which is closest to the information disk substrate. Layer is the than the closest side layer in the dummy disc substrate, preceded to UV curing, the virtual semi-cured layer formed during this, the occurrence of the back transfer is suppressed.

(2) The ultraviolet curing of the adhesive layer is completed within a shorter time by performing the flash irradiation from the dummy substrate side synchronously with the flash irradiation from the outside of the information disk substrate side. Can be.

(3) By controlling two or more flashing ultraviolet irradiating means provided respectively on both outer sides of one of the laminated disks by using two switching means which open and close with a time difference therebetween, The flash irradiation from the outside of the information disk substrate can be performed prior to the flash irradiation from the outside of the dummy disk substrate, and after a predetermined time (with a time difference), the dummy disk substrate can be irradiated. Flash irradiation from the side can be started. Also, after a predetermined time, flash irradiation from both outer sides can be stopped.

[0093]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention includes the following embodiments. 1.2 One of the two is an information disc substrate having an ultraviolet-transmissive and visible light-reflective information recording layer on an ultraviolet-transparent substrate, and the other is an ultraviolet-transparent print on an ultraviolet-transparent substrate. A dummy disk substrate having a layer, or a thin film having an ultraviolet light transmitting and visible light reflecting film on an ultraviolet light transmitting substrate, wherein a dummy pit group not used for information recording is provided on the thin film. A dummy disk substrate having an ultraviolet-transparent and visible-light-reflective thin film in which a pattern is depicted by shading or size of said dummy disk;
The two disk substrates are bonded using an ultraviolet-curable composition as an adhesive, and the information recording surface of the information disk substrate and the printed surface of the dummy disk substrate or the surface depicting the design are facing each other, and are bonded together. UV light is repeatedly flashed from both outer sides of a single disk
A method of bonding the information disk substrate and the dummy disk substrate by curing the adhesive, wherein at any time between the time when the flash irradiation is started and the time when the flash irradiation is completed. , Flash irradiation energy on the disk substrate surface (unit: J)
Wherein a value obtained by multiplying the information disk is illuminated such that the direction from the outside of the information disk substrate is always larger than the direction from the outside of the dummy disk substrate. Lamination method.

2. The flash irradiation from both outer sides of the bonded single disk is performed synchronously, and the repetition rate of the flash irradiation from both outer sides is constant. The method according to the above item 1, wherein E1> E2 when the irradiation energy (unit J) per flash on the disk substrate surface per flash is E1 and E2, respectively.

3. The repetition rate of the flash irradiation from both outer sides of the one disk formed by bonding is constant;
When the number of times of flash light irradiation from the outside of the information disk substrate and the number of times of flash light irradiation from the outside of the dummy disk substrate are respectively N1 and N2 (N1 and N2 are natural numbers), N1> N2. 2. The method according to the above item 1.

4. The above-described 1, 2 or above, wherein the repeated flash irradiation of the ultraviolet light is performed by a plurality of light source lamps.
3. The method according to any one of the above items 3.

[0097] 5. The ultraviolet curable composition contains a photopolymerization initiator, and the absorption wavelength region of the photopolymerization initiator and the wavelength region of the ultraviolet light emitted by the light source lamp overlap as widely as possible. 2, the above 3,
Alternatively, the method according to any one of the above items 4.

6. From light emitted from the light source lamp, infrared rays unnecessary for curing the ultraviolet curable composition,
The method according to any one of the above-described 1, 2, 3, 4, or 5, which removes a light beam such as a visible light and irradiates ultraviolet rays with a flash.

7. The energy of the light radiated from the information disk substrate side and the energy of the light radiated from the dummy disk substrate side are made the same, and the ultraviolet light is reduced between the flash type irradiation means on the dummy disk substrate side and the dummy disk substrate (optical path). 7. The method according to any one of the above-described 1, 2, 3, 4, or 5, or 6, wherein the flash irradiation is performed such that an optical filter to be disposed is arranged.

8. The flash irradiation is performed so as to provide a difference between the (optical path) distance between the flash irradiation means on the information disk substrate side and the information disk substrate and the (optical path) distance between the flash irradiation means and the information disk substrate on the dummy disk substrate side. The above-mentioned 1, the above-mentioned 2, the above-mentioned 3, the above-mentioned 4, or the above-mentioned 5, the above-mentioned 6,
The method according to any of the above.

9. One of the two substrates is an information disk substrate having an ultraviolet-transmissive and visible light-reflective information recording layer on an ultraviolet-transparent substrate, and the other is an ultraviolet-transparent substrate on an ultraviolet-transparent substrate. It is a dummy disk substrate having a printing layer, or has an ultraviolet-transparent and visible light-reflective thin film on an ultraviolet-transparent substrate, and provides a dummy pit group not for information recording in the thin film, A dummy disk substrate having an ultraviolet-transparent and visible-light-reflective thin film in which a pattern is drawn by shading and the size of a pit group, wherein the two disk substrates are formed by using an ultraviolet-curable composition as an adhesive, and The information recording surface of the disk substrate and the printed surface or the surface depicting the design of the dummy disk substrate are attached to each other so as to face each other. The ultraviolet from the outside repeatedly irradiated flashlight, said information an apparatus for bonding the disc substrates and said dummy disk substrate by curing the adhesive, on both outer sides of the disk 1
One or more flash ultraviolet irradiation means, two switching means which are opened and closed with a time difference allowing flash of the flash ultraviolet irradiation means, and a flash irradiation from the outside of the information disk substrate, Control means for controlling said two switching means so as to precede irradiation of flash light from the outside of the dummy disk side.

10. The above-mentioned 9 which provides a filter for blocking infrared rays on an optical path between the light source lamp and the disk.
The described device.

Next, a preferred embodiment of the present invention will be described. First, a thermoplastic resin with excellent heat resistance is melted, cast into a stamper in which grooves corresponding to recorded information are engraved in the circumferential direction, cooled, and a disc-shaped information recording disk substrate with grooves is cut. obtain.

Next, a metal is sputtered on the surface on which the groove is formed, so as to have a predetermined thickness. The sputtered thin film reflects visible light for reproduction at a high rate,
Generally, ultraviolet rays do not transmit much. According to the findings of the present inventors, the transmittance of an aluminum sputtered thin film having a thickness of 400 angstroms at a light wavelength of 400 nm is only about 0.3%. On this metal thin film,
Liquid ultraviolet curing, which has excellent adhesion to the metal thin film so as to have a smooth surface, including irregularities on the thin film caused by the grooves and the like, and can form a cured product that transmits ultraviolet light at a high rate. A mold resin is applied and cured by ultraviolet irradiation to form a protective coat layer. However, the protective coat layer may be omitted if it can be determined that the protective coat layer is not particularly required in terms of quality. A required number of such disk substrates are prepared.

In the case where the information disk substrate is provided with the protective coat layer, the set-off which is the object of the present invention is relatively reduced as compared with the case where the protective coat layer is not provided. It is difficult to completely eliminate them. The thickness of the protective coating layer itself is usually 5 to 8 μm, which is considered to be a reason that it is considerably thin. Therefore, it is desirable to employ the method of the present invention even when the protective coating layer is provided.

With the information recording layer of the disk substrate facing upward, the wavelength range of the ultraviolet rays to be flashed, which will be described later, which can form a cured product having excellent adhesion to the information recording layer, overlaps as much as possible. A liquid ultraviolet curable composition containing a photopolymerization initiator having an absorption wavelength region such as described above is dropped, and a predetermined film thickness is in a range of 20 to 60 μm, usually 40 μm.
m.

When the method of the present invention is applied, the thickness of the adhesive layer made of the ultraviolet-curable composition is 40 as described above.
It is desirable to be about μm. If the thickness is extremely thinner than that, it is difficult to join the entire joining surfaces of the two disk substrates without any gap. On the other hand, if the thickness is extremely large, the production cost of the disk increases, and it becomes difficult to completely cure the adhesive layer with ultraviolet rays in the entire thickness direction.

Then, when the composition is in an uncured state,
The other pre-printed substrate or the dummy substrate of the pit image substrate is bonded to each other with good adhesion so that air bubbles and foreign matter are not mixed. At this time, if necessary, a weight that transmits ultraviolet light may be applied in order to maintain sufficient adhesion.

Then, the gas-filled flash lamp for the ultraviolet light source is connected to a flash discharge mechanism obtained based on the circuit shown in FIG. 4, and the auxiliary electrode of the numeral 9 connected to the high-voltage pulse generating circuit of the numeral 10 is connected. , Around the flash lamp of the numeral 8. The DC high-voltage power supply (not shown) is of a variable voltage type, and the capacitor of numeral 6 and the air-core coil of numeral 7 are of a detachable structure that can be appropriately replaced with those of other capacities, if necessary. By exchanging these circuit elements and operating them, the peak value and the 1/3 time width of the discharge current waveform (the current value rises from zero and becomes 1/3 of the peak value, and then attenuates again to 1/3 And the curing conditions such as the repetition rate of the lamp emission can be optimized from the viewpoint of the apparatus.

The minimum required electric input energy (the CV
^In order to carry out the ultraviolet flash curing at a value of 2/2), the flash emission spectrum of the flash lamp indicated by numeral 8 in FIG. 4 indicates that the photopolymerization initiator contained in the ultraviolet-curable composition reacts sharply. In order to adjust the peak value and the 1/3 time width of the discharge current waveform, which are supplied to the flash lamp of the numeral 8, so that the absorption wavelengths of the ultraviolet light and the photopolymerization initiator overlap in the widest possible wavelength region. Further, it is preferable to select the type and combination of materials to be included in the photopolymerization initiator.

In general, even when lamps having the same shape are used, when discharging is performed by increasing the charging voltage of the capacitor indicated by numeral 6 in FIG. 4, the voltage peak value at the time of discharging increases, and as a result, the ultraviolet wavelength of 400 nm or less is obtained. The spectral intensity of the region relatively increases. Further, even if the charging voltage of the capacitor of the numeral 6 is constant, as the inductance of the air-core coil of the numeral 7 decreases, the 1/3 time width decreases and the peak value of the discharge current waveform increases, As a result, the spectral intensity in the ultraviolet wavelength region having a wavelength of 400 nm or less relatively increases. Thus the number 8
The emission spectrum of the flash lamp can be controlled to some extent by changing the discharge current peak value and the 1/3 time width at the time of emission.

On the other hand, there are two types of photopolymerization initiators contained in the ultraviolet curable composition, a type in which molecules are cleaved to generate radicals and a type in which an aromatic ketone and a hydrogen donor are combined. As described above, the absorption spectrum of ultraviolet rays differs depending on the selection and combination of these materials.

Therefore, in order to complete the ultraviolet curing of the ultraviolet-curable composition with the minimum necessary electric input energy, the side of the flash type ultraviolet irradiation device and the side of the material of the ultraviolet-curable composition are required. Therefore, it is desirable to find and use optimal conditions so that both wavelength regions overlap as widely as possible.

In order to minimize the effect of heat from the lamp during flash irradiation, a filter or the like for blocking infrared rays is provided on the optical path between the flash lamp light source and the disk.

Then, as shown in FIG. 4 as an example, a lamp light source is arranged on both outer sides of one disk formed by bonding two disk substrates, using an irradiation device of a discharge mechanism capable of repeatedly irradiating flash light. Irradiation is performed such that the flash irradiation from the outside of the information disk substrate is larger than the flash irradiation from the outside of the dummy disk substrate in terms of the integrated irradiation energy. For example, one from each side
If the irradiation energy on the disk substrate surface per flash is the same, flash light irradiation is performed once or more from the outside of the side having the information disk substrate, and thereafter, a predetermined time difference T1
And the flash irradiation from the outside on the other dummy disk substrate side may be continuously performed once or more. In the latter flash irradiation, the flash irradiation from each side may be performed synchronously.

Alternatively, the energy per one flash irradiation on the disk substrate surface from each side is ΔE (unit: J) from the outside of the information disk substrate side to the energy from the outside of the dummy disk substrate side. ), The flash irradiation from each side may be performed synchronously from the first shot. Since the energy E per flash is determined by CV ^2/2, the energy difference of the △ E, in the case of the circuit configuration of FIG. 4 shown as an example, the flash lamp is arranged on both outer sides of the disk Since the charged voltage to the connected capacitor of the numeral 6 has the same value, it can be achieved by giving a difference to the capacitance C (unit: F, Farad) of the numeral 6 capacitor. That is, the capacitance of the capacitor of the flash lamp circuit that irradiates the information disk substrate from outside may be set to a value larger than that of the dummy disk substrate.

Alternatively, in the circuit configuration of FIG. 4 shown as an example, a DC power supply for temporarily storing electric charges in the capacitor of number 6 is separately provided for each of the flash lamps arranged on both outer sides of the disk. If this is not the case (not shown), the energy difference ΔE can be given by simply changing the charging voltage on each side without changing the capacitance C of the number 6 connected to each flash lamp. it can. In this case, the charging voltage of the flash lamp disposed outside the information disk substrate may be higher than that of the dummy lamp substrate.

The T1 and ΔE represent the smallest set-off due to the ultraviolet transmittance of the printed layer or the layer provided with the pit image provided on the information disk substrate or the dummy disk substrate, and the curing is hardened. May be appropriately adjusted so that the operation is completed within a short time.
In this way, a highly reliable bonded disc with little set-off is obtained.

[0119]

【Example】

 <Embodiment 1> An embodiment of the present invention will be described in detail.

First, the disk substrate having the information recording layer used in this embodiment is a substrate made of polycarbonate resin having a thickness of 0.6 mm, and the information recording layer has a light transmittance of 0.3% at a wavelength of 400 nm. This is a sputtered film made of aluminum having a thickness of 450 °.

The dummy substrate is made of a polycarbonate resin having a thickness of 0.6 mm, and has been printed in advance on the side to be bonded to the information recording disk substrate. Although the light transmittance of the printing layer at a wavelength of 400 nm varies depending on the location in the printing surface, it is approximately 0.3% to
It is in the range of 1.5%.

FIG. 5 is a sectional view showing the structure of the lamp section. Numeral 8 in FIG. 5 is a xenon flash lamp (10.5 mm inside diameter, 200 m arc length) manufactured by Ushio Inc.
m), numeral 14 is a window made of quartz glass, numeral 15 is an ultraviolet-transparent 5 mm thick tray for holding a disk, numeral 16 has a structure shown in FIG. The adhesive layer of the ultraviolet curable resin represents a disk in an uncured state. The ultraviolet curable composition used in this example is SD-318 manufactured by Dainippon Ink and Chemicals, Inc.

In FIG. 5, the distance between the lamp center axes of the adjacent lamps is 36 mm, the distance from the lamp center axis to the lamp window is 25 mm, and the distance between the upper and lower lamp windows is 20 mm.
mm.

The flash irradiating apparatus of Example 1 had four power supply systems, and two xenon lamps were connected in series for one power supply system. Therefore, two power supply systems were provided for the upper four lamps in the layout of FIG. 5, and two power supply systems were similarly provided for the lower four lamps.

The main circuit constants are as follows.
μF, and the inductance of the air core coil is 330 μH. The charging voltage is 1800 V. In this case, the luminous energy (unit J) per lamp per light emission is about 2
00J.

The light emission of the lamps arranged on each of the upper and lower sides is controlled by a trigger input terminal (a terminal corresponding to numeral 11 in FIG. 3) of the power supply circuit so that at least four lamps on each side emit synchronous light. Is connected to give a control signal (light emission command).

In such an apparatus, at the timing shown in FIG. 6, first, five flash irradiations from the information disk substrate side, and subsequently, five simultaneous flash irradiations from both sides are carried out.
No. 6 disks. Numeral 17 in FIG. 6 indicates a control pulse signal indicating a flash irradiation instruction, numeral 18 indicates a pulse train indicating the timing of a light emission instruction given to a lamp disposed on the side of the dummy substrate, and numeral 19 indicates a disk substrate having an information recording layer. 7 is a pulse train showing the timing of a light emission command given to a lamp on the side. The pulse repetition rate is 5 times / sec on each side.

The time required for flash irradiation in this example was about 2 seconds, and the disk with the cured adhesive layer had almost no set-off. Also, after confirming that there was no set-off, the two bonded substrates were separated and the adhesive layer was observed. The observed adhesive layer had sufficient hardness, and was sufficiently cured by ultraviolet light. It turned out that it was done.

In this embodiment, a very strong flash was emitted from the xenon lamp at the time of irradiation. However, the flash irradiation damaged the aluminum sputtered layer and the printed layer provided on the disk substrate and changed their color. I didn't do anything. <Example 2>

Next, a disk substrate having an information recording layer is the same as that in the first embodiment, and an embodiment in which pit art is used as a dummy substrate will be described.

The dummy substrate in the second embodiment is made of a polycarbonate resin having a thickness of 0.6 mm, and a pattern, a character or the like is previously drawn on the side to be the adhesive surface with the information recording disk substrate by pit art. And a sputtered film made of aluminum is provided thereon.

The light transmittance of the pit art layer at a wavelength of 400 nm varies depending on the location on the disk substrate surface, but is generally in the range of 0.2% to 0.5%. However, since irregular reflection of incident light occurs on the slope of the pit, the variation in light transmittance when viewed more microscopically is considered to be larger than the measured value.

In Example 2, the UV-curable composition as an adhesive was manufactured by Dainippon Ink and Chemicals, Inc.
D-318 was used. Then, when the same flash irradiation was performed in the case of Example 1, the disc after irradiation had almost no set-off. Also, after confirming that there was no set-off, the two bonded substrates were separated and the adhesive layer was observed. The observed adhesive layer had sufficient hardness, and was sufficiently cured by ultraviolet light. It turned out that it was done.

[0134]

As described above, in the present invention,
As a dummy disk substrate, a preprinted substrate or a pit image substrate is used, an ultraviolet curable composition is used as an adhesive, and the substrate is bonded to a disk substrate having an information recording layer. When the flash irradiation is repeatedly performed, the energy of the flash irradiation on the disk substrate surface (unit: J) at any time from the start of the flash irradiation to the end of the flash irradiation ) Is greater from the outside of the information disc substrate,
By adopting a method of irradiating the flash so that the size is always larger than that from the outside of the dummy disk substrate side, it is possible to obtain a bonded disk with less set-off and high reliability.

In the second aspect of the present invention, by employing the method of the first aspect of the present invention, since the flash irradiation is performed synchronously at a constant repetition rate from both outer sides of the disk, the irradiation is completed within a short time. Thus, a bonding device having a simple structure can be provided.

[0136]

[Brief description of the drawings]

[0137]

FIG. 1 is a sectional view showing a DVD-5 format disc structure.

[0138]

FIG. 2 is a cross-sectional view illustrating a DVD-5 format disk structure when bonded using a preprinted or pit image disk substrate.

[0139]

FIG. 3 is a schematic diagram of a power supply circuit for supplying power to a xenon lamp.

[0140]

FIG. 4 is an electric circuit diagram showing an example of the configuration of the device of the second invention.

[0141]

FIG. 5 is a cross-sectional view illustrating a structure of an ultraviolet flash irradiation unit in which four xenon lamps are arranged on both sides of the disk.

[0142]

FIG. 6 is a diagram showing timings of control signals for individually giving a flash irradiation command to a lamp group installed above the disk and a lamp group installed below the disk.

[0143]

[Explanation of symbols]

Reference Signs List 1 disk substrate having information recording layer 2 information recording layer 3 dummy disk substrate 4 adhesive layer (ultraviolet curable resin) 5 printing layer or pit image layer 6 capacitor 7 air core coil 8 xenon flash lamp (manufactured by USHIO Inc.) 9) Auxiliary electrode 10 High voltage pulse generating circuit 11 Trigger input terminal 12 Diode 13 Control signal generating circuit L1 Xenon flash lamp provided outside information disk substrate side L2 Xenon flash lamp provided outside dummy disk substrate side SW1 Symbol L1 Switch means for controlling ON / OFF of lamp SW2 Switch means for controlling ON / OFF of lamp L2 14 UV-transmittable quartz glass window 15 UV-transmittable tray 16 Structure of FIG. 2 formed by bonding two substrates together Disk 17 with flash Pulse train representing the timing of irradiation from a disk substrate having a pulse train 19 information recording layer that represents the timing of irradiation from the side of the pulse signal 18 dummy disc substrate representing a command

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Kiyoshi Oshima 6982-8-101 Motojuku, Komuro, Ina-cho, Kita-Adachi-gun, Saitama Inside (72) Inventor Masahiko Kotoyori Origin Electric Co., Ltd. 1-1-18 Takada, Toshima-ku, Tokyo

Claims (5)

[Claims] 1. An information disc substrate having an ultraviolet-transmissive and visible-light-reflective information recording layer on an ultraviolet-transparent substrate, and the other one having an ultraviolet-transparent substrate on an ultraviolet-transparent substrate. Either a dummy disk substrate having a printing layer, or an ultraviolet-transmitting substrate having a thin film that is ultraviolet-transmissive and visible light-reflective, providing a dummy pit group not for information recording in the thin film, A dummy disk substrate having a thin film that is transparent to ultraviolet light and visible light, depicting a pattern by shading and the size of the dummy pit group, using the two disk substrates as an adhesive with an ultraviolet-curable composition, The information recording surface of the information disk substrate and the printed surface of the dummy disk substrate or the surface on which the pattern is drawn are attached to each other so as to face each other. A method of bonding the information disk substrate and the dummy disk substrate by repeatedly irradiating ultraviolet rays repeatedly from the outside and curing the adhesive, wherein the flash irradiation is started from the time when the flash irradiation is started. At any time before the end time, the value obtained by integrating the flash irradiation energy on the disk substrate surface is greater from outside the information disk substrate side than from the dummy disk substrate side. The method of laminating disks according to claim 1, further comprising irradiating a flash so as to always increase the size. 2. The information recording disk substrate according to claim 1, wherein the flash irradiation from both outer sides of the bonded single disk is synchronous, and the repetition rate of the flash irradiation from both outer sides is constant. When the irradiation energies on the disk substrate surface per flash performed from the outside of the dummy disk substrate side and from the outside of the dummy disk substrate side are E1 and E2, respectively,
The method of claim 1, wherein 1> E2. 3. The repetition rate of flash light irradiation from both outer sides of one of the bonded disks is constant, and the flash light from the outer side of the information disk substrate and from the outer side of the dummy disk substrate. N1 and N
2 (N1 and N2 are both natural numbers), N1> N2
The method of claim 1, wherein 4. The ultraviolet curable composition contains a photopolymerization initiator, and the absorption wavelength range of the photopolymerization initiator and the wavelength range of the ultraviolet light to be irradiated overlap as widely as possible. A method according to any of claims 2 or 3. 5. One of the two substrates is an information disk substrate having an ultraviolet-transmissive and visible light-reflective information recording layer on an ultraviolet-transparent substrate, and the other is an ultraviolet-transparent substrate on an ultraviolet-transparent substrate. Either a dummy disk substrate having a printing layer, or an ultraviolet-transmitting substrate having a thin film that is ultraviolet-transmissive and visible light-reflective, providing a dummy pit group not for information recording in the thin film, A dummy disk substrate having a thin film that is transparent to ultraviolet light and visible light, depicting a pattern by shading and the size of the dummy pit group, using the two disk substrates as an adhesive with an ultraviolet-curable composition, The information recording surface of the information disk substrate and the printed surface of the dummy disk substrate or the surface on which the pattern is drawn are attached to each other so as to face each other. A device for bonding the information disk substrate and the dummy disk substrate by irradiating ultraviolet rays from the outside at a constant repetition rate to cure the adhesive, one for each of the outer sides of the disk. The flash type ultraviolet irradiating means provided above, two switching means which are opened and closed with a time difference for allowing flashing of the flash type irradiating means, and the flash disk irradiation from the outside of the information disk substrate to the dummy disk substrate And a control means for controlling the two switching means so as to precede the flash irradiation from the outside of the disk.