JP2004095012A - Laminated sheet for optical disk - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a laminated sheet for an optical disk, by which a light transmissive film is retained with a holding film, even at the work for sticking the light transmissive film to an optical disk substrate while stripping off a releasing film. <P>SOLUTION: The retaining film 1 having an adhesive layer 7 on one side, the light transmissive film 2, the one side of which is laminated to the side of the adhesive layer 7 of the retaining film 1 while having an adhesive layer 9 at another side, and the releasing film 3 laminated to the side of the adhesive layer 9 of the light transmissive film 2, are successively laminated, and when the interfaces of each of these laminated films 1, 2, 3 are expressed by a, b in this order, the adhesive strength of each of the interfaces a, b are made b<a. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a laminated sheet for an optical disc, which includes, as a part of the configuration, a light-transmitting film used for an optical disc for recording and reproducing information by irradiating a laser beam having a short wavelength of 550 nm or less.
[0002]
[Prior art]
Recently, as a medium for recording a larger amount of information, an optical information recording medium for recording and reproducing information by irradiating a laser beam having a short wavelength, particularly a laser beam having a wavelength of 405 nm, has been developed. The optical disk used for this has a recording layer on a disk substrate having a thickness of 1.1 mm, and a light-transmitting film having a thickness of 100 μm is laminated for the purpose of protecting the recording layer.
[0003]
Conventionally, as a method of laminating this light-transmitting film, an ultraviolet-curing adhesive is applied to the recording layer of the optical disk substrate by a spin coating method, and the light-transmitting film base material is adhered and then irradiated with ultraviolet light to be fixed. And a method in which the adhesive surface of the light-transmitting film that has been adhesively processed on one side is bonded to the recording layer of the optical disc.
[0004]
Among these, when using a light-transmissive film that has been subjected to adhesive processing, in order to efficiently and continuously adhere to the optical disk substrate, the light-transmitting film that has been punched into an optical disk shape is held by the holding film. It is preferable that
Therefore, a laminated sheet has been devised in which a release film is used as a holding film, and an adhesive layer of a light-transmitting film in the form of an optical disc faces a release surface of the release film.
[0005]
However, when the laminated sheet having this configuration is used, since the light-transmitting film is not held at the stage where the release film is peeled off for performing the bonding operation, a means for holding the light when bonding is devised. I needed to.
[0006]
[Problems to be solved by the invention]
The present invention has been made in order to solve the above-described problems, a holding film having an adhesive layer on one side, and an adhesive layer on the other side by laminating one side to the adhesive layer side of the holding film. When the interfaces of the respective films obtained by sequentially laminating the light transmitting film having the film and the release film laminated on the adhesive layer side of the light transmitting film are a and b, the adhesive force of each interface a and b is When the work is performed such that b <a, the release film can be peeled off and the light-transmitting film can be held by the holding film even when the light-transmitting film is bonded to the optical disk substrate. It is intended to provide a laminated sheet.
Still another object of the present invention is to provide a laminated sheet for an optical disc having a configuration in which the surface of the optical disc is covered with a protective film even after each of the optical discs that have undergone the laminating operation is peeled off from the holding film. .
[0007]
[Means for Solving the Problems]
Means of the present invention for achieving the above-mentioned object,
A holding film having an adhesive layer on one side, a light transmitting film having an adhesive layer on the other side by laminating one side to the adhesive layer side of the holding film, and a laminating layer on the adhesive layer side of the light transmitting film When a holding film, a light transmissive film, and a release film are sequentially laminated, and the interfaces of the respective films are sequentially denoted by a and b, the adhesive force of each interface a and b is b. <a> in the configuration of the laminated sheet for an optical disk configured to satisfy <a>.
[0008]
Then, a holding film having an adhesive layer on one side surface, a surface protective film having one side surface laminated on the adhesive layer side of the holding film and having an adhesive layer on the other side surface, A light-transmitting film having an adhesive layer on the other side and a side-layer laminated, and a release film laminated on the adhesive layer side of the light-transmitting film, and these holding film, surface protective film, and light-transmitting film And the release film are sequentially laminated. When the interfaces of the respective films are sequentially denoted by c, d, and e, the optical disc for the optical disk is configured such that the adhesive force of each of the interfaces c, d, and e satisfies e <c <d. In the configuration of the laminated sheet.
[0009]
A polycarbonate film is used as a base material of the light transmitting film.
[0010]
A film obtained by a co-extrusion method is used as a surface protective film of a light-transmitting film having an adhesive layer.
[0011]
An optical disc-shaped light transmitting film and a release film are laminated on a holding film having an adhesive layer.
[0012]
On the holding film having the adhesive layer, a surface protection film of a light-transmitting film in the form of an optical disc, a light-transmitting film, and a release film are laminated.
[0013]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, an optical disc laminated sheet according to an embodiment of the present invention will be described in detail with reference to the drawings.
In FIGS. 1 and 3, W is a laminated sheet for an optical disc, which shows the first embodiment, and is basically composed of a holding film 1, a light-transmitting film 2 and a release film 3.
[0014]
For example, as shown in FIG. 2, the optical disc 4 has, on an optical disc substrate 5 having a thickness of 1.1 mm, a recording layer 6 made of a metal reflection layer or the like, and an optical disc for protecting the recording layer 6. It has a structure in which a transparent film 2 is laminated, and records and reproduces information by irradiating a laser beam to the recording layer 6 through the light transparent film 2.
Here, the optical disk substrate 5 is made by injection molding a plastic material, for example, a polycarbonate resin, an acrylic resin, a polystyrene resin, a vinyl chloride resin, an epoxy resin, or a polyester resin, but it is necessary to be optically transparent. And it need not necessarily be a plastic material. Therefore, it can be made of glass, ceramics, metal or the like. Of these, polycarbonate resins are usually used from the viewpoint of processability, moisture resistance, and dimensional stability.
[0015]
The recording layer 6 is made of a metal reflective layer, a magneto-optical recording layer, an organic dye layer, a layer change recording layer, or a combination thereof.
A light transmissive film 2 as a protective layer for protecting the recording layer 6 from scratches and the like is laminated on the recording layer 6, and the laminated sheet W for an optical disc according to the embodiment of the present invention uses the light transmissive film 2 as a protective film. The structure is such that it can be easily attached to the optical disk substrate 5.
[0016]
The holding film 1 is a so-called carrier film, which has an adhesive layer 7 on one side, and is formed on a recording layer 6 of an optical disk substrate 5 by a light transmitting film 2 described later. In the pre-adhesion step, the light-transmitting film 2 formed into an outer shape of the optical disc 4 and the release film 3 laminated on the light-transmitting film 2 are held, that is, the holding is performed. The film 1 serves as a supporting base material when the half of the optical disc 4 is processed from the release film 3 side described later to the light transmissive film 2 described later, and serves as a transport film in the bonding step.
The holding film 1 requires a moderate thickness, strength, and dimensional stability, and has a thickness of 25 μm or more, preferably 38 μm or more, which is obtained by subjecting one surface of a polyester, polyethylene, or polypropylene film to adhesive processing, A film obtained by extruding and laminating a thermoplastic resin of a base film such as polyolefin and an adhesive component together is used. In addition, a configuration in which two or more types of films are laminated can be employed. Among these, those using a polyester film provided with an adhesive layer 7 as a base material are preferable, exhibit relatively high strength, and are retained when rolled and stored. It has shape.
The adhesive layer 7 is made of an acrylic adhesive, a rubber adhesive, a silicone adhesive, or the like.
[0017]
In the above-described light-transmitting film 2, one side surface of the light-transmitting film substrate 8 is laminated on the adhesive layer 7 side of the holding film 1, and an adhesive layer 9 is formed on the other side surface of the light-transmitting film substrate 8. Have
The light transmissive film 2 includes a light transmissive film substrate 8 and an adhesive layer 9.
As the light-transmitting film substrate 8, a film having high transparency and dimensional stability and having a small birefringence, for example, a film of polyester, polycarbonate, amorphous polyolefin, acryl, or the like is preferable. Among them, polycarbonate obtains transparency as a film. It is most preferable in that it has good optical characteristics and has very little birefringence of light. Here, the surface opposite to the adhesive layer 9 can be hard-coated with a UV curable resin or the like for the purpose of improving the surface of the light transmissive film substrate 8 from scratching.
The above-mentioned adhesive layer 9 is made of an acrylic adhesive, a rubber-based adhesive, a silicone-based adhesive, or, if necessary, a commonly known adhesive such as a UV-curable type. Acrylic pressure-sensitive adhesives are particularly preferred in terms of weather resistance and economy. Further, a material having a refractive index close to that of the substrate is more preferable.
[0018]
The thickness of the light-transmitting film 2 is 90 to 110 μm, and the thickness ratio of the light-transmitting film base material 8 to the adhesive layer 9 is 95: 5 to 50:50, more preferably 90:10 to 65: 35.
As a method of forming the adhesive layer 9 on the light-transmitting film substrate 8, a method of directly applying the above-mentioned adhesive to the light-transmitting film substrate 8, or a release surface of a release-treated film A method of transferring the adhesive by applying a pressure-sensitive adhesive to the substrate and then bonding the light-transmitting film substrate 8 thereto can be employed.
[0019]
The release film 3 is laminated on the adhesive layer 9 side of the light transmitting film 2, and in the process until the light transmitting film 2 is attached to the recording layer 6 of the optical disc 4, the adhesive layer 9 is formed. Is to protect.
The release film 3 is a film having at least one side surface that has a good or good release property from the pressure-sensitive adhesive, and the release surface is in contact with the pressure-sensitive adhesive layer 9 of the light-transmitting film 2. They are stacked together.
As a method of releasing the film base material into the release film 3, a method of applying a release agent such as a silicone-based or fluorine-based release agent is used. The release film 3 preferably has a smooth surface in consideration of the effect on the adhesive surface of the light transmitting film 2 to be combined. If the thickness is too small, dents and the like damage the adhesive layer 9. When the thickness is too large, it is not economical, and the thickness is preferably 12 to 100 μm, and particularly preferably 20 to 60 μm.
[0020]
Then, in the laminated sheet W for an optical disk according to the embodiment of the present invention, the interface of each of the films 1, 2, 3 in which the holding film 1, the light-transmitting film 2, and the release film 3 are sequentially laminated is described. When a and b are set, the bonding force of each interface a and b is configured to satisfy b <a.
[0021]
In the laminated sheet W for an optical disk, the following functions and effects are exhibited by designing the interfaces a and b to have the above-described peel strength.
That is, when the laminated sheet W for an optical disk is in the laminated state, as shown in FIG. 3A, it has a rectangular (long) shape having a margin 10 larger than the outer shape of the optical disk 4. Shape).
[0022]
The rectangular laminated sheet W for an optical disc is half-cut from the release film 3 side to the light-transmitting film 2 into an outer shape (circular planar shape) of the optical disc 4, and the inner peripheral portion of the optical disc 4 is rounded. Complete punching.
Then, by removing 10 margins of the release film 3 and the light transmitting film 2 larger than the outer shape of the optical disc 4, the outer shape of the optical disc 4 is placed on the holding film 1 as shown in FIG. Thus, a laminated sheet W1 for an optical disc having a configuration in which the light transmissive film 2 and the release film 3 having the above structure are laminated can be obtained.
[0023]
When laminating the optically transparent film 2 to the optical disk substrate 5 in the optical disk laminated sheet W1, as shown in FIG. 4A, the release film of the optical disk laminated sheet W1 is used. 3 is removed to expose the adhesive layer 9 of the light transmissive film 2, and the adhesive between the recording layer 6 surface of the optical disc substrate 5 and the light transmissive film 2 is removed by a conventional processing machine as shown in FIG. The lamination with the layer 9 is performed.
Then, after the bonding of the recording layer 6 surface of the optical disk substrate 5 and the adhesive layer 9 of the light transmissive film 2 is completed, as shown in FIG. Separated from 4.
At this time, the holding film 1 is peeled off together with the adhesive layer 7 provided on one side thereof, and the optical disc 4 has a light-transmitting film with respect to the recording layer 6 of the optical disc substrate 5 as shown in FIG. A finished product in which the light transmitting film 2 is laminated via the adhesive layer 9 provided on the base material 8 is obtained.
[0024]
Therefore, if the adhesive force between the interfaces a and b is a <b, when the release film 3 is to be peeled, the applied peel force is applied to the adhesive layer 9 of the release film 3. The light-transmitting film 2 does not act on the adhesive layer 7 provided on the light-transmitting film substrate 8, and as a result, the light-transmitting film 2 is peeled off from the holding film 1. The bonding of the substrate 5 and the light transmissive film 2 cannot be performed smoothly, smoothly, and reliably.
[0025]
Therefore, when laminating the optically transparent film 2 to the optical disk substrate 5 in the optical disk laminated sheet W1, when the release film 3 is to be peeled off, the adhesive It is necessary to cause the release film 3 to peel off, and the condition of this action is to design the adhesive force of the interfaces a and b so that a> b.
[0026]
In FIG. 6, W is a laminated sheet for an optical disc according to the second embodiment, in which a holding film 1 having an adhesive layer 7 on one side and one side of the holding film 1 on the side of the adhesive layer 7 of the holding film 1 are laminated. A surface protection film 12 having an adhesive layer 11 on the other side surface, a light transmitting film 2 having one side surface laminated on the other side surface of the surface protection film 12 and an adhesive layer 9 on the other side surface, and a light transmitting film 2 2, a release film 3 laminated on the side of the pressure-sensitive adhesive layer 9, and films 1, 12, and 12 in which the holding film 1, the surface protection film 12, the light transmitting film 2, and the release film 3 are sequentially laminated. Assuming that the interfaces 2 and 3 are c, d, and e, respectively, the separation force of each of the interfaces c, d, and e satisfies e <c <d.
[0027]
In the second embodiment, since the film structure of the holding film 1, the light transmitting film 2, and the release film 3 is the same as that of the first embodiment, the same members are denoted by the same reference numerals. A detailed description of the configuration of these same members 1, 2, 3 will be omitted with reference to the description of the first embodiment.
The feature of the optical disc laminated sheet W shown in this example is that it has a surface protection film 12 for protecting the outer surface of the light transmitting film 2 in addition to the configuration described in the first example.
[0028]
The surface protective film 12 of the light transmissive film 2 is a film having the adhesive layer 11 on the other side similarly to the configuration of the holding film 1, and the other side of the film such as polyester, polyethylene, or polypropylene is subjected to adhesive processing. A film obtained by extruding and laminating a thermoplastic resin of a base film such as polyolefin and a pressure-sensitive adhesive component together is used. Since the surface protective film 12 is supported by the holding film 1, no special film strength is required.
By using a film obtained by coextrusion of this surface protective film, the film can be produced at low cost.
[0029]
As described above, the laminated sheet W for an optical disc has an interface between the holding film 1 and the surface protection film 12 interposed between the holding film 1 and the light transmitting film 2 as shown in FIG. When the interface between the surface protective film 12 and the light-transmitting film 2 is d and the interface e between the light-transmitting film 2 and the release film 3 is e, the peeling force at each of the interfaces c, d, and e is e <c <d. Designed to be.
[0030]
In the laminated sheet W for an optical disc, the following functions and effects are exhibited by designing each of the interfaces c, d, and e to have the peel strength described above.
That is, when the laminated sheet W for an optical disk is in the laminated state, as shown in FIG. 7A, the laminated sheet W has a rectangular (elongated) shape having a margin 10 larger than the outer shape of the optical disk 4. Shape).
[0031]
The rectangular laminated sheet W for an optical disc is half-cut from the release film 3 side to the light-transmitting film 2 into an outer shape (circular planar shape) of the optical disc 4, and the inner peripheral portion of the optical disc 4 is rounded. Complete punching.
Then, by removing 10 margins of the release film 3, the light transmitting film 2, and the surface protection film 12 which are larger than the outer shape of the optical disc 4, as shown in FIG. An optical disc laminated sheet W1 having a configuration in which the release film 3, the light transmissive film 2, and the surface protection film 12 having the outer shape of the optical disc 4 are laminated can be obtained.
[0032]
When laminating the light transmissive film 2 to the optical disk substrate 5 in the optical disk laminated sheet W1, as shown in FIG. 8A, the release film of the optical disk laminated sheet W1 is used. 3 is removed, the adhesive layer 9 of the light transmitting film 2 is exposed, and the surface of the recording layer 6 of the optical disk substrate 5 and the light transmitting film 2 are removed by a conventional processing machine as shown in FIG. A bonding process with the adhesive layer 9 is performed.
After the bonding of the recording layer 6 surface of the optical disk substrate 5 and the adhesive layer 9 of the light transmissive film 2 is completed, the optical disc 4 with the surface protection film 12 and the light transmissive film 2 is removed from the holding film 1 as shown in FIG. As shown in FIG. 9B, by pulling apart, a finished product in which the light transmitting film 2 and the surface protection film 12 are laminated on the recording layer 6 of the optical disc 4 as shown in FIG. 9 is obtained.
[0033]
Therefore, when the adhesive force of the interfaces c and e described above is c <e when the release film 3 is to be peeled off, the given peeling force is applied to the adhesive layer 9 of the release film 3. The light-transmitting film 2 does not act on the adhesive layer 7 provided on the light-transmitting film substrate 8, and as a result, the light-transmitting film 2 is peeled off from the holding film 1. The bonding of the substrate 5 and the light transmissive film 2 cannot be performed smoothly, smoothly, and reliably.
Further, when the adhesive force between the interfaces d and e is d <e, the given peeling force is not applied to the adhesive layer 9 of the release film 3, and the peeling force is applied to the surface protection film 12. The light-transmitting film 2 works first on the side of the provided adhesive layer 11, and as a result, there arises a disadvantage that the light-transmitting film 2 is peeled off from the holding film 1 together with the release film 3. 5 cannot be bonded.
Furthermore, if the adhesive force between the interfaces c and d is c> d, the applied peeling force is not applied to the adhesive layer 7 of the holding film 1, and the peeling force is applied to the surface protection film 12. As a result, the surface protection film 12 is peeled off from the light transmitting film 2 and the surface protection film 12 remains on the holding film 1.
[0034]
Therefore, when the light transmitting film 2 is bonded to the optical disk substrate 5 in the optical disk laminated sheet W1, when the release film 3 is to be peeled off, first, the adhesive Due to the necessity of causing the release film 3 to peel off and then the necessity of causing the surface protective film 12 of the light transmitting film 2 and the holding film 1 to peel off, the conditions for these adhesive forces are as follows. Design is made such that e <c <d for the interfaces c, d, and e.
[0035]
Next, each embodiment of the laminated sheet W for an optical disc according to the embodiment of the present invention will be described in comparison with a comparative example.
[Example 1]
One side of a 38 μm-thick biaxially stretched polyester film is blended with 2-ethylhexyl acrylate / methyl methacrylate / vinyl acetate / hydroxyethyl methacrylate / acrylic acid at a 40/40/16/16/3 ratio by weight. Then, using a 2.2′-azobis-isobutylonitrile as a catalyst, a removable acrylic pressure-sensitive adhesive having a degree of polymerization Mw of 700 to 800,000 and a solid content of 30% obtained by polymerization in ethyl acetate under a nitrogen stream, It is blended with Coronate L in a weight ratio of 100: 3 and has a solid content of 20 g / m2. ² The coating was dried at 100 ° C. for 3 minutes to form an adhesive layer 7, which was used as a holding film 1.
Next, on a release surface of a biaxially stretched polyester film 8 having a thickness of 25 μm obtained by coating a silicone-based release agent on one side surface, a polymerization obtained by polymerizing n-butyl acrylate as a main component in the same manner as described above. A permanent adhesive type acrylic pressure-sensitive adhesive having a degree of Mw = 80-1,000,000 and a solid content of 30% was mixed with Coronate L in a weight ratio of 100: 2, and a solid content of 22 g / m2 was used. ² Coating and drying at 100 ° C. for 3 minutes formed an adhesive layer 9.
Further, an 80 μm-thick cast polycarbonate film (trade name: Pure Ace: manufactured by Teijin Limited) 3 was bonded to obtain a film having a configuration in which the release film 3 was laminated on the light-transmitting film 2.
Finally, the pressure-sensitive adhesive layer 7 of the holding film 1 and the polycarbonate film surface of the above-mentioned laminated film were bonded together to obtain a laminated sheet W for an optical disk having the configuration of the present invention.
[0036]
The peeling force by 180 ° peeling of the holding film 1 and the light transmitting film 2 and the release film 3 and the light transmitting film 2 were 0.3 N / 50 mm and 0.1 N / 50 mm, respectively.
[0037]
After slitting the laminated sheet W for an optical disk to a width of 140 mm, the half of the optical disk from the release film 3 side to the light-transmitting film 2 is half-punched, and the inner periphery of the optical disk is fully punched. By removing the film 3 and the light transmitting film 2, as shown in FIG. 3 (b), a film having a configuration in which the optical disk shaped light transmitting film 2 and the release film 3 are laminated on the holding film 1. w1 was obtained.
The release film 3 is peeled off, and a disc substrate 5 on which a recording layer 6 is formed by sputtering an Ag film and spin-coating a metal-containing azo dye on a polycarbonate substrate having a thickness of 1.1 mm is bonded to the polycarbonate substrate. Thus, an optical disk 4 which can be written was obtained.
[0038]
The bonding operation to the disk substrate 5 can be performed continuously and stably because the light-transmitting film 2 is held by the holding film 1, and the obtained optical disk 4 has no warp. No error occurred during writing of the data or reproducing / reading the information.
[Example 2]
Density 0.898g / cm ³ 80% by weight of ethylene-α-olefin copolymer having a density of 0.923 g / cm ³ Pressure-sensitive adhesive layer-forming resin mixture of low-density polyethylene and a density of 0.940 g / cm ³ And a high-density polyethylene were co-extruded from a flat die to produce a surface protective film 12 composed of a laminated film having a total thickness of 60 μm and an adhesive layer thickness of 15 μm.
The surface protective film 12 prepared above was laminated on a polycarbonate film having a thickness of 80 μm, and the holding film 1 prepared in the same manner as in Example 1 was further laminated on the surface protective film 12.
Next, an acrylic pressure-sensitive adhesive layer was formed on the release surface of a biaxially stretched polyester film having a thickness of 25 μm coated with a silicone release agent on one side in the same manner as in Example 1, and the above-described protective film of a polycarbonate film was laminated. By bonding the uncoated surfaces, a laminated sheet W for an optical disk having the configuration of the embodiment of the present invention (see FIG. 6) was obtained.
[0039]
The peeling forces of the holding film 1 and the surface protective film 12, the surface protective film 12 and the light transmitting film 2, and the light transmitting film 2 and the release film 3 by 180 ° peeling are 0.25, 0.4, and 0.1, respectively. (N / 50 mm).
After slitting the laminated sheet W for an optical disk to a width of 140 mm, half the blanking process is performed from the release film 3 side to the surface protection film 12 into an optical disk shape, and the inner peripheral portion of the optical disk is fully punched. By removing the light-transmitting film and the protective film, as shown in FIG. 8B, the optical disk-shaped surface protective film 12, the light-transmitting film 2, and the release film 3 are laminated on the holding film 1. A film having the following composition was obtained.
[0040]
The release film 3 was peeled off, the disk substrate 5 was bonded, and then separated from the holding film 1 to obtain an optical disk 4 having a surface protection film 12 and capable of writing at a wavelength of 405 nm.
[0041]
The bonding operation to the disk substrate can be performed continuously and stably because the light-transmitting film 2 is held by the holding film 1. No error occurred during writing or reading / reproducing the information.
[0042]
Further, since the surface protection film 12 is provided, the disk can be sealed in the cartridge without scratching the surface of the optical disk 4.
[0043]
[Comparative Example 1]
An adhesive layer was formed on the release surface of a 50 μm-thick biaxially stretched polyester film obtained by applying a silicone release agent on one side and then a polycarbonate film was adhered according to Example 1. A film having a configuration in which a transparent film was laminated was obtained.
After slitting this laminated film to a width of 140 mm, the light transmissive film is half-punched into an optical disk shape, the inner periphery of the optical disk is fully punched out, and the light transmissive film outside the disk is removed to hold the release film. As a film, a film having a configuration in which a light-transmitting film in the form of an optical disk was laminated was obtained.
Since the work of bonding to the disk substrate cannot be performed while the light transmitting film is held by the holding film, the work of continuously and stably bonding to the disk substrate cannot be performed. Further, the obtained optical disk was warped, and an error occurred at the time of recording and writing and reproduction.
[0044]
[Comparative Example 2]
A laminated film was obtained in the same manner as in Example 1 except that the type of the silicone release agent in Example 1 was changed and the 180 ° peeling force between the light transmitting film and the release film was set to 0.4 N / 50 mm.
The resulting laminated film was peeled off together with the light-transmitting film from the holding film when the release film was peeled off, and it was not possible to continuously and stably bond the laminated film to the disc substrate.
[0045]
[Comparative Example 3]
Except that in Example 2, the weight ratio of the removable acrylic pressure-sensitive adhesive of the holding film to Coronate L was 100: 1, and the 180 ° peeling force between the holding film and the surface protective film was 0.5 N / 50 mm. Obtained a laminated film according to Example 2.
When the obtained laminated film is peeled off from the holding film after being bonded to the disk substrate, it peels off at the interface between the surface protection film and the light-transmitting film, and is sealed in a cartridge without scratching the optical disk surface. Could not.
[0046]
【The invention's effect】
By using the laminated sheet for an optical disk of the present invention, a light transmitting film can be efficiently bonded to an optical disk substrate.
Furthermore, even after each of the optical discs that have been pasted together are peeled off from the holding film, the surface of the light-transmitting film is covered with the protective film, and scratches and dirt adhere to the optical disc surface in a later process. Can be prevented.
[Brief description of the drawings]
FIG. 1 is a longitudinal sectional view showing a main part of a first embodiment of a laminated sheet for an optical disk of the present invention.
FIG. 2 is a perspective view showing an optical disc using the optical disc laminated sheet in FIG.
3A and 3B show a part of the laminated sheet for an optical disk in FIG. 1, wherein FIG. 3A is a plan view and FIG. 3B is a sectional view.
FIG. 4 is a longitudinal sectional view of a main part showing each state of use of the laminated sheet for an optical disk in FIG. 1;
FIG. 5 is a perspective view showing a state in which the optical disk laminated sheet in FIG. 1 is laminated on an optical disk.
FIG. 6 is a longitudinal sectional view showing a main part of a second embodiment of the laminated sheet for an optical disk of the present invention.
7 (a) is a plan view, and FIG. 7 (b) is a sectional view, showing a part of the laminated sheet for an optical disk in FIG.
8 is a longitudinal sectional view of a main part showing each state of use of the laminated sheet for an optical disk in FIG. 6;
9 is a perspective view showing a state where the laminated sheet for an optical disk in FIG. 1 is laminated on an optical disk.
[Explanation of symbols]
W ... Laminated sheet for optical disk. 1. Retaining film. 2: Light transmissive film. 3: Release film. 4: Optical disk. 12 Surface protection film.

Claims (6)

A holding film having an adhesive layer on one side, a light transmitting film having an adhesive layer on the other side by laminating one side to the adhesive layer side of the holding film, and a laminating layer on the adhesive layer side of the light transmitting film When a holding film, a light transmissive film, and a release film are sequentially laminated, and the interfaces of the respective films are sequentially denoted by a and b, the adhesive force of each interface a and b is b. <a laminated sheet for an optical disk characterized by being configured to satisfy <a>. A holding film having an adhesive layer on one side, a surface protective film having an adhesive layer on the other side by laminating one side to the adhesive layer side of the holding film, and one side of the surface protecting film to the other side. A light-transmitting film having an adhesive layer laminated on the other side and a release film laminated on the adhesive layer side of the light-transmitting film. When the interface of each film obtained by sequentially laminating the mold film is c, d, e, the adhesive force of each interface c, d, e satisfies e <c <d. Laminated sheet for optical disks. 3. The laminated sheet for an optical disc according to claim 1, wherein a polycarbonate film is used as a base material of the light transmitting film. The laminated sheet for an optical disc according to claim 2, wherein a film obtained by a co-extrusion method is used as a surface protective film of the light transmitting film having an adhesive layer. 2. The laminated sheet for an optical disc according to claim 1, wherein the optical disc-shaped light transmissive film and the release film are laminated on a holding film having an adhesive layer. 3. The laminated sheet for an optical disc according to claim 2, wherein a surface protective film of an optically disc-shaped light transmissive film, a light transmissive film, and a release film are laminated on a holding film having an adhesive layer.

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