JP2003338089A - Optical information recording medium - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical information recording medium which has a hard coat layer of high hardness, is hardly splotched due to its low critical surface tension, has small warpage when used as a card and excellent bending resistance. <P>SOLUTION: In the optical information recording medium having the hard coat layer 11 on the light incident surface side of a transparent substrate 12 at which a recording layer 17 is provided, the hard coat layer 11 contains a UV curing resin and a surface reforming agent consisting of a siloxane compound. The hard coat layer 11 contains a UV curing resin layer consisting of an acrylmonomer having a colloidal silica group and the surface reforming agent consisting of the siloxane compound and the content of the surface reforming agent consisting of the siloxane compound is 0.1 to 1.0 pts.wt. to 100 pts.wt. acrylmonomer having the colloidal silica group. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to an optical information recording medium.

[0002]

2. Description of the Related Art In general, an optical card recording medium (hereinafter abbreviated as an optical card) has a hard coat layer 1 on the back surface of a transparent substrate 2 having an uneven preformat 6 formed on its surface as shown in FIG. Is provided, the recording layer 7 and the visible information 4 are provided on the surface on which the preformat 6 is formed, and the protective base material 3 is provided on the recording layer 7 via the adhesive 8. It has a structure in which visible information 4 is formed on the outer surface. For recording and reproducing information, recording / reproducing light 5 is irradiated through the transparent substrate 2 to record or reproduce information on the recording layer 7.

Thus, the optical card requires at least the transparent substrate 2, the recording layer 7 and the protective base material 3. The recording / reproducing laser beam passes through the transparent substrate 2 and reaches the recording layer 7 to record information on the recording layer 7, or is weakened to about 1/10 and used for reproducing information.

Therefore, in the optical card, the transparent substrate laminated on the recording layer is required to have scratch resistance, and the hard coat layer is laminated. In particular, the optical card is considered to be used as a medical card that is always carried by an individual, and requires stronger scratch resistance than other optical discs, CDs (compact discs), and the like.

Acrylic resins such as polymethylmethacrylate, polycarbonate resins, epoxy resins and polyolefin resins are used as transparent substrates for optical cards, and some optical cards using these resins as transparent substrates are put on the market. There is. Acrylic resin substrates have the advantage of high surface hardness and resistance to scratches, but lack flexibility, while polycarbonate resins and polyolefin resins have excellent flexibility, but they have low surface hardness and tend to be scratched. Cheap.

A method of providing a hard coat layer to protect the surface of such a transparent substrate has been proposed. For example, Japanese Patent Application Laid-Open No. 2-239438 discloses that two or more hard coat layers are provided on a transparent substrate and the hardness of the hard coat layer is increased toward the outermost layer. It has been reported that better flexibility and higher hardness of card media can be obtained.

Optical card media include CD, CD-R, and DVD
A major difference from the optical disc-shaped recording medium such as is that the card is supposed to be bent. ISO
The standard and JIS standards also define static bending characteristics and dynamic bending characteristics.

On the other hand, a hard coat layer made of an ultraviolet curable resin or a thermosetting resin is formed on the surface of the transparent substrate of the optical card so as not to be scratched. If the surface of the transparent substrate through which the recording / reproducing light is transmitted is scratched, the recording / reproducing light is scattered and the probability of an error during recording / reproducing information on the optical card increases.

[0009]

A hard hard coat layer coat has been developed in order to prevent the surface of the hard coat layer from being damaged. However, the hard hard coat layer is less likely to be scratched, but there is a problem that cracks occur in the hard coat layer when the card is bent. If a crack is generated on the surface of the hard coat layer when the optical card is bent, it has the same effect as when the surface of the card is scratched, and the error rate of information optical recording / reproduction increases.

In order to improve both the flexibility and hardness of the hard coat layer, JP-A-2-239438 discloses a hard coat layer having flexibility and high hardness by using a multilayer hard coat layer. Is disclosed. But,
Since the hard coat layer is multi-layered, there are problems that the manufacturing cost becomes high and the production yield decreases. Further, the thickness of the hard coat layer is 4 to 6 μm, which is insufficient for a transparent substrate using a resin having a relatively soft surface hardness such as polycarbonate resin and olefin resin.

The inventors of the present invention have proposed in JP-A-8-147763 that the hard coat layer must have a thickness of 6 μm or more in order to improve the surface hardness of a transparent substrate using a polycarbonate or olefin resin. . JP-A-8-14
Japanese Patent No. 7763 discloses a hard coat layer composed of three layers. However, in each of the present inventions, the steps of applying the hard coat layer are performed a plurality of times, and the problems such as a decrease in the yield during manufacturing and a high cost remain.

Further, in Japanese Unexamined Patent Publication (Kokai) No. 8-161772, an ultraviolet-curable resin is added to ethylene / acrylic ester.
A hard coat layer having a maleic anhydride copolymer added is disclosed. However, the critical surface tension of the surface of the hard coat layer becomes large, and there is a problem in that the card surface is likely to be stained. As with scratches, the adhesion of dirt on the surface of the hard coat layer causes an error during recording and reproduction of information.

Has sufficient bending characteristics as an ID card,
In addition, the development of a hard coat layer that is not easily scratched on the surface and is unlikely to attach dirt has been insufficient. Further, thickening the hard coat layer causes a problem that the card is warped. In particular, when the hard coat layer is formed on the transparent substrate before the protective substrate and the transparent substrate are bonded together, the transparent substrate on which the hard coat layer having a thickness of at least 6 μm is formed has a large warp of the transparent substrate.
There is a problem that it becomes difficult to position the bonding when bonding the protective substrate.

The present invention has been made in order to solve the above problems of the prior art, and the hardness of the hard coat layer is high, the critical surface tension is small, stains hardly occur, and the card warp is small. It is also an object of the present invention to provide an optical information recording medium excellent in bending resistance.

[0015]

That is, the present invention provides an optical recording medium having a hard coat layer on the light incident surface side of a transparent substrate provided with a recording layer, wherein the hard coat layer is an ultraviolet curable resin and a siloxane. An optical information recording medium characterized by containing a surface modifier comprising a compound.

It is preferable that the ultraviolet curable resin comprises an acrylic monomer having a colloidal silica group. It is preferable that the ultraviolet curable resin comprises an acrylic monomer.
The content of the surface modifier composed of the siloxane compound is
The amount is preferably 0.1 to 1.0 part by weight with respect to 100 parts by weight of the monomer forming the ultraviolet curable resin.

The hard coat layer contains an ultraviolet curable resin made of an acrylic monomer having a colloidal silica group and a surface modifier made of a siloxane compound, and the content of the surface modifier made of a siloxane compound is It is preferably 0.1 to 1.0 part by weight based on 100 parts by weight of the acrylic monomer having a colloidal silica group.

The critical surface tension of the surface of the hard coat layer is preferably 250 μN (25 dyn) or less. The thickness of the hard coat layer is preferably 6 to 10 μm.

[0019]

BEST MODE FOR CARRYING OUT THE INVENTION The optical information recording medium of the present invention is an optical recording medium having a hard coat layer made of an ultraviolet curable resin on the light incident surface side of a transparent substrate, and the surface made of a siloxane compound in the ultraviolet curable resin. It is characterized in that it contains a modifier, and the surface modifier has the effects of curing shrinkage modification of the ultraviolet curable resin and reducing the critical surface tension.

The optical information recording medium of the present invention, having the above-mentioned constitution, is flexible and has a hard coat layer which is hard to be scratched on the surface and hard to be soiled on the surface. Things are possible.

FIG. 1 is a schematic view showing an embodiment of the optical information recording medium of the present invention. As shown in FIG. 1, a hard coat layer 11 is provided on the back surface of a transparent substrate 12 having an uneven preformat 16 formed on the surface thereof, and a recording layer 17 is provided on the surface of the front surface having the preformat 16 formed thereon. Layer 1
7 has a structure in which a protective base material 13 is provided on an adhesive 7 via an adhesive 18, and visible information 4 is formed on the outer surface of the protective base material 3. For recording and reproducing information, recording / reproducing light 15 is irradiated through the transparent substrate 12 to record or reproduce information on the recording layer 17.

The present invention is an improvement of the hard coat layer 11 provided on the light incident surface side of the transparent substrate 12 provided with the recording layer 17, and the hard coat layer 11 is composed of an ultraviolet curable resin and a siloxane-based resin. It is characterized by containing a surface modifier composed of a compound.

The surface modifier composed of a siloxane compound added to the ultraviolet curable resin in the present invention has the effect of reducing the critical surface tension of the surface of the hard coat layer composed of the ultraviolet curable resin. The hard coat layer has not only a high hardness of the resin but also a critical surface tension of the hard coat layer surface of 250 μN (25 dyn) or less, preferably 200 μN (20 dyn) to 100 μN (10 dy).
The present inventors have found that in the case of n), the hard coat layer surface is less likely to be soiled and the hard coat layer surface is less likely to be scratched. As the critical surface tension of the surface decreases, the frictional resistance of the surface decreases. Therefore, the surface of the hard coat layer having a small critical surface tension does not generate scratches because the frictional resistance between the surface of the hard coat layer and the substance to be rubbed is not increased.

The thickness of the hard coat layer is adjusted to 6 to 10 μm, preferably 6 to 8 μm. Thickness is 6
When the thickness is less than μm, the hardness of the hard coat layer surface is affected by the hardness of the transparent substrate. For example, the pencil hardness of the surface is 3B
Even if a hard coat layer having a thickness of 3 μm is formed on the surface of a polycarbonate having a certain degree, the surface hardness can be improved only to about B. Further, if the thickness exceeds 10 μm, the bending resistance of the hard coat layer decreases, and cracks easily occur when the transparent substrate is bent.

The precursor (state before ultraviolet curing) for forming the hard coat layer used in the present invention comprises an ultraviolet curable resin, a photopolymerization initiator, a surface modifier and a viscosity adjusting diluent solvent.

After the ultraviolet curing, the cured ultraviolet curing resin and the surface modifier are mainly present on the surface of the transparent substrate. Unreacted UV curable resin and unreacted photopolymerization initiator are included as impurities.

As the ultraviolet curable resin used in the present invention, the following oligomers of and are preferably used. Acrylic oligomer having two or more acryloyl groups (-0OC-CH = CH ₂₎ in the molecule. Specific examples of the acrylic oligomer are shown below.

[0028]

[Chemical 1]

An acrylic monomer or oligomer combined with colloidal silica represented by the following structural formula.

[0030]

[Chemical 2]

In the formula, A represents silica such as silanol-treated colloidal silica particles or acrylsilane-treated colloidal silica particles. R represents an alkylene group having 1 to 4 carbon atoms.

The hard coat layer obtained from the acrylic monomer bonded with the colloidal silica is harder than the hard coat layer obtained from the acrylic oligomer, has a high bending resistance, and is characterized by less cracking when bent. .

The siloxane compound of the surface modifier used in the present invention is a polyether-modified dimethylpolysiloxane copolymer, a polyether-modified methylalkylpolysiloxane copolymer, a polyester-modified dimethylpolysiloxane, a polyester-modified methylpolysiloxane, etc. Can be used.

The amount of the siloxane compound added is 0.1 to 1 part by weight, preferably 0.2 to 0.8 part by weight, relative to 100 parts by weight of the monomer forming the ultraviolet curable resin.
More preferably, 0.3 to 0.8 parts by weight is desirable. If the amount added is in this range, the thickness of the hard coat layer is 6 μm.
Even with the above, the warp of the card can satisfy the standard of ISO 7810. By adding the siloxane compound, it is possible to reduce the curing shrinkage of the ultraviolet curable resin during ultraviolet curing. Further, there is an effect that the surface is less likely to be scratched.

If the amount of the siloxane compound added is less than 0.1 part by weight, the above effects of the present invention cannot be obtained. Also, 1
If the siloxane-based compound is added in excess of parts by weight, the hardness of the hard coat layer is reduced, and further, the ultraviolet curing of the ultraviolet curable resin is inhibited and the cross-linking strength of the hard coat layer resin is reduced. To do. When the hard coat layer formed on the transparent substrate is bent, cracks easily occur.

As the photopolymerization initiator used in the present invention, the following substances are used. The addition amount of the photopolymerization initiator is 1 to 1 with respect to 100 parts by weight of the monomer forming the ultraviolet curable resin.
0 parts by weight is preferred.

[0037]

[Chemical 3]

[0038]

[Chemical 4] Viscosity adjusting solvent used in the present invention, for example, methyl acetate,
Ethyl acetate, butyl acetate, benzene, toluene, xylene, isopropyl alcohol, ethanol and a mixed solvent of these solvents are used.

Next, the method for forming the hard coat layer in the present invention will be described. The coating liquid for forming the hard coat layer used in the present invention is blended with the above ultraviolet curable resin, a photopolymerization initiator, a surface modifier, a diluent solvent for viscosity adjustment, and other additives as necessary. And prepare.

The coating solution can be applied to the transparent substrate by spin coating, roll coating, direct gravure coating, bar coating, or the like. Depending on the coating method,
Adjust the viscosity of the coating liquid. The viscosity is adjusted by adjusting the amount of the diluent solvent added to the ultraviolet curable resin. It is preferable to adjust the thickness of the hard coat layer to 6 to 8 μm after ultraviolet curing.

Next, curing is performed by irradiating ultraviolet rays.
The ultraviolet irradiation energy is preferably about ²⁰ to 200 mJ / cm ² . For example, in the case of a conveyor type irradiation device using a high pressure mercury lamp, the lamp power of the high pressure mercury lamp is 80
~ 160 W / cm, distance between lamp and sample is 100 ~ 15
0 mm and a conveyor speed of 1 to 30 m / min are preferable.

The transparent substrate suitable for forming the hard coat layer used in the present invention is preferably a plastic substrate having a thickness of 5 mm or less, preferably 2 mm or less. When the thickness is 5 mm or less, the plastic substrate may bend, and the effect of the hard coat layer of the present invention becomes remarkable.

Polycarbonate, acrylic resin, polyethylene, polypropylene, nylon resin, styrene resin and the like can be used as the plastic material of the substrate. If necessary, in order to improve the adhesiveness between the hard coat layer and the resin substrate, the surface of the resin substrate can be subjected to corona treatment or the like.

The recording layer, adhesive and protective substrate used in the optical information recording medium of the present invention are not particularly limited,
It is possible to use a material that is normally used.
For example, as the recording layer, a laminated film of a dye / gold reflective film is used in CD-R and the like. Also, organic dyes, TeO _2, etc. are used in optical cards and the like. Also, rewritable phase change materials are used for DVDs and the like.

[0045]

EXAMPLES The present invention will be specifically described below with reference to examples.

[0046]   Example 1   A1: Composition of coating liquid for hard coat layer     UV curable resin: 100 parts by weight         Multifunctional acrylic resin, Unidick 17-806     Polysiloxane: 0.3 parts by weight         BYK325 (polyether-modified methylalkylpolysiloxane (bit (Kukemy Japan Co., Ltd.))     Photopolymerization initiator; lrgacure-184 2 parts by weight     Viscosity adjusting solvent; 70 parts by weight         Butyl acetate: Toluene (7: 3) mixed solution

B: UV curing conditions Conveyor type irradiation device using high pressure mercury lamp Lamp power of high pressure mercury lamp; 160W / cm Distance between lamp and sample: 120 mm Conveyor speed: 1m / min

Preformed thickness 0.4
The coating liquid A1 is applied by spin coating to the surface of the polycarbonate transparent substrate of mm having no preformat, the solvent is removed in an oven at 50 ° C. for 2 minutes, and then the coating film is cured under the curing conditions of B. Then, a hard coat layer having a thickness of 9 μm was obtained.

Next, a recording layer made of a dye represented by the following structural formula (1) was formed to a thickness of 1000 Å, and the thickness was set to 80 μm.
A protective substrate having a thickness of 0.3 mm was attached via an adhesive of m and cut into a card size to obtain an optical card having a thickness of 0.78 mm.

[0050]

[Chemical 5]

Example 2 A card-shaped recording medium was obtained in the same manner as in Example 1 except that the coating liquid of the following composition A2 was used instead of the coating liquid of Example 1.

[0052]   A2: Composition of coating liquid for hard coat layer     UV curable resin: 100 parts by weight         Multifunctional acrylic resin, Unidick 17-806     Polysiloxane: 0.4 parts by weight         BYK333 (polyether-modified dimethylpolysiloxane (Big Chem ー Japan Co., Ltd.))     Photopolymerization initiator; lrgacure-184 2 parts by weight     Viscosity adjusting solvent; 70 parts by weight         Butyl acetate: Toluene (7: 3) mixed solution

Example 3 A card-shaped recording medium was obtained in the same manner as in Example 1 except that the coating liquid of the following composition A3 was used instead of the coating liquid of Example 1.

[0054]   A3: Composition of coating liquid for hard coat layer     UV curable resin: 100 parts by weight         Silicone / acrylic resin monomer, UVHC1105     Polysiloxane: 0.6 parts by weight         BYK333 (polyether-modified dimethylpolysiloxane (Big Chem ー Japan Co., Ltd.))     Photopolymerization initiator; lrgacure-184 2 parts by weight     Viscosity adjusting solvent; 80 parts by weight         Butyl acetate: Toluene (7: 3) mixed solution

Example 4 A card-shaped recording medium was obtained in the same manner as in Example 1 except that the coating liquid of the following composition A4 was used in place of the coating liquid of Example 1.

[0056]   A4: Composition of coating liquid for hard coat layer     UV curable resin: 100 parts by weight         Silicone / acrylic resin monomer, UVHC1105     Polysiloxane: 0.4 parts by weight         BYK325 (polyether-modified dimethylpolysiloxane (Big Chem ー Japan Co., Ltd.))     Photopolymerization initiator; lrgacure-184 2 parts by weight     Viscosity adjusting solvent; 80 parts by weight         Butyl acetate: Toluene (6: 4) mixed solution

Example 5 A card-shaped recording medium was obtained in the same manner as in Example 1 except that the coating liquid of the following composition A5 was used instead of the coating liquid of Example 1.

[0058]   A5: Composition of coating liquid for hard coat layer     UV curable resin: 100 parts by weight         Silicone / acrylic resin monomer, UVHC1105     Polysiloxane: 0.2 parts by weight         BYK333 (polyether-modified dimethylpolysiloxane (Big Chem ー Japan Co., Ltd.))     Photopolymerization initiator; lrgacure-184 2 parts by weight     Viscosity adjusting solvent; 80 parts by weight         Butyl acetate: Toluene (6: 4) mixed solution

Example 6 A card-shaped recording medium was obtained in the same manner as in Example 1 except that the coating liquid having the following composition A6 was used instead of the coating liquid of Example 1.

[0060]   A6: Composition of coating liquid for hard coat layer     UV curable resin: 100 parts by weight         Silicone / acrylic resin monomer, UVHC1105     Polysiloxane: 0.4 parts by weight         BYK333 (polyether-modified dimethylpolysiloxane (Big Chem ー Japan Co., Ltd.))     Photopolymerization initiator; lrgacure-184 2 parts by weight     Viscosity adjusting solvent; 80 parts by weight         Butyl acetate: Toluene (7: 3) mixed solution

Example 7 A card-shaped recording medium was obtained in the same manner as in Example 1 except that the coating liquid having the following composition A7 was used in place of the coating liquid of Example 1.

[0062]   A7: Composition of coating liquid for hard coat layer     UV curable resin: 100 parts by weight         Silicone / acrylic resin monomer, UVHC1105     Polysiloxane: 0.8 parts by weight         BYK333 (polyether-modified dimethylpolysiloxane (Big Chem ー Japan Co., Ltd.))     Photopolymerization initiator; lrgacure-184 2 parts by weight     Viscosity adjusting solvent; 80 parts by weight         Butyl acetate: Toluene (6: 4) mixed solution

Comparative Example 1 A card-shaped recording medium was obtained in the same manner as in Example 1 except that the coating liquid of the following composition A8 was used in place of the coating liquid of Example 1.

[0064]   A8: Composition of coating liquid for hard coat layer     UV curable resin: 100 parts by weight         Silicone / acrylic resin monomer, UVHC1105     Polysiloxane: 1.2 parts by weight         BYK333 (polyether-modified dimethylpolysiloxane (Big Chem ー Japan Co., Ltd.))     Photopolymerization initiator; lrgacure-184 2 parts by weight     Viscosity adjusting solvent; 80 parts by weight         Butyl acetate: Toluene (7: 3) mixed solution

Comparative Example 2 A card-shaped recording medium was obtained in the same manner as in Example 1 except that the coating liquid of the following composition A9 was used instead of the coating liquid of Example 1.

A9: Composition of coating liquid for hard coat layer UV curable resin: 100 parts by weight Silicone / acrylic resin monomer, UVHC1105 photopolymerization initiator; lrgacure-184 2 parts by weight Viscosity adjusting solvent; 80 parts by weight Butyl acetate: Toluene ( 7: 3) Mixed solution The results of measuring the hardness, bending test, critical surface tension, and amount of warpage of the card-shaped recording media of Examples 1 to 7 and Comparative Examples 1 to 2 are shown in Table 1 below. .

Measuring Method (1) Steel Wool Hardness With # 0000 steel wool, the load (g) with which the surface of the hard coat is scratched is shown.

[0068]

[Table 1]

Next, FIG. 2 shows polysiloxane (BYK33
The relationship between the scratch resistance (steel wool hardness value) of the hard coat layer and the bending resistance (cylindrical bending diameter) according to the addition amount of 3) is shown. The composition of the coating liquid for the hard coat layer in FIG. 2 is the same as that in Example 2 except for polysiloxane (BYK333).

From the results shown in FIG. 2, polysiloxane (BYK
333) in the range of 0.2 to 0.8 parts by weight,
The effect of adding polysiloxane (BYK333) is recognized. On the other hand, it was found that when 1.2 parts by weight or more was added, the hardness decreased and the bending resistance also decreased.

[0071]

As described above, according to the present invention, it is possible to obtain a card-shaped optical information recording medium in which the hardness of the hard coat layer is high and the bending resistance is excellent. In addition, since the critical surface tension of the surface of the hard coat layer is small, stains are less likely to occur than in the conventional hard coat layer, and the error rate at the time of recording / reproduction due to dust adhesion is reduced. Further, even when the thickness of the hard coat layer was 6 μm or more, the curing shrinkage of the hard coat layer could be reduced, and a card-shaped optical information recording medium having a small card warp and satisfying the standard of the ID card could be obtained.

[Brief description of drawings]

FIG. 1 is a schematic view showing an embodiment of an optical information recording medium of the present invention.

FIG. 2 is a graph showing the relationship between the amount of polysiloxane (BYK333) added, the scratch resistance of the hard coat layer (steel wool hardness value), and the bending resistance (cylindrical bending diameter).

FIG. 3 is a schematic view showing an embodiment of a conventional optical information recording medium.

[Explanation of symbols]

1,11 Hard coat layer 2,12 transparent substrate 3,13 Protective base material 4,14 Visible information 5,15 Recording / reproducing light 6,16 preformat 7,17 Recording layer 8,18 adhesive

Claims (7)

[Claims] 1. An optical recording medium having a hard coat layer on the light incident surface side of a transparent substrate provided with a recording layer, wherein the hard coat layer contains an ultraviolet curable resin and a surface modifier made of a siloxane compound. An optical information recording medium characterized by: 2. The optical information recording medium according to claim 1, wherein the ultraviolet curable resin comprises an acrylic monomer having a colloidal silica group. 3. The optical information recording medium according to claim 1, wherein the ultraviolet curable resin comprises an acrylic monomer. 4. The content of the surface-modifying agent comprising the siloxane-based compound is such that the monomer 10 forming an ultraviolet-curing resin.
0.1 to 1.0 parts by weight with respect to 0 parts by weight.
The optical information recording medium described. 5. An ultraviolet curable resin, wherein the hard coat layer comprises an acrylic monomer having a colloidal silica group,
A surface modifier containing a siloxane-based compound, and the content of the surface modifier containing a siloxane-based compound is 0.1 to 1.0 part by weight based on 100 parts by weight of the acrylic monomer having the colloidal silica group. The optical information recording medium according to claim 1, which is a part. 6. The critical surface tension of the surface of the hard coat layer is 250 μN (25 dyn) or less.
The optical information recording medium according to any one of 1. 7. The film thickness of the hard coat layer is 6 to 10 μm.
6. The optical information recording medium according to any one of claims 1 to 5.