JP2517644B2 - Optical recording medium - Google Patents

Description

The present invention relates to an optical recording medium, more specifically,
The present invention relates to an inexpensive and good quality optical recording medium.

[Conventional technology]

Conventionally, as an optical recording medium, a method of directly providing a metal thin film layer on a disc obtained by injection molding and then applying an overcoat (for example, Nikkei Electronics 19
Issued November 28, 1977, pages 81-91) has been widely practiced.

[Problems to be Solved by the Invention]

However, the above-mentioned conventional optical recording medium has the drawbacks of poor productivity and high unit price per sheet because the metal thin film is provided by batch processing. An object of the present invention is to provide an optical recording medium that solves the above problems, is inexpensive, has excellent productivity, and has good quality.

[Means for solving the problem]

The optical recording medium of the present invention is an optical recording medium for recording information signals such as video, audio and characters at a high density. A signal recording layer, a metal thin film layer, a polyester biaxially stretched film and a coating layer are laminated in this order. The coating layer is composed of a laminate, and the coating layer is composed mainly of inert inorganic particles having an average particle diameter of 0.11 to 0.70 μm and a water-soluble or water-dispersible resin, and the average particle diameter (D) of the inert inorganic particles and the coating. The layer thickness (d) ratio (D / d) is 1.1-
It is characterized by being 80.

The present invention relates to an optical recording medium that can be used as an optical reproducing, optical recording, or magneto-optical recording substrate, among which an optical recording medium having a signal recording layer, a metal thin film layer, a polyester biaxially stretched film, and a specific coating layer in this order. The present invention relates to a recording medium.

Of course, if necessary, an adhesive layer or the like may be provided between the layers. The adhesive layer used here is not particularly limited, and representative examples thereof include acrylic adhesives, particularly UV-curable acrylic adhesives, epoxy adhesives, and vinyl chloride-vinyl acetate copolymers.

The signal recording layer in the present invention is not particularly limited, but as a typical one, one obtained by deforming after softening the substrate itself made of a thermoplastic or thermosetting resin such as polycarbonate, acryl, or epoxy resin because it is heat or solvent, or These thermoplastic or thermosetting resins, inorganic materials such as glass, layers using various photoresists on various substrates made of metal such as aluminum, Cr, Pb, Au, Rh, Zn, Cu, S
b, Te, TeOx, In, Bi, CS 2 -Te, metal thin film layers such as Te-C, an amorphous thin film layer such as Aste, various dye thin film layer, reflectance change layer such as silver + polymer, MnBi, GdCo Dielectric layers were provided on various recording layers such as a thermomagnetic material layer such as, an amorphous semiconductor layer such as As-Se-S-Ge, or a layer whose transmittance changes such as styrene oligomer + dye, if necessary. I can list things. However, among them, it is preferable to use a substrate which is softened and deformed by various solvents or heat so that the cost reduction effect becomes more remarkable.

The metal thin film layer (A) in the present invention is provided as a laser light reflection layer and is not particularly limited, but it is usually provided in a thickness of 5 to 10000 nm by a method such as vapor deposition or sputtering. A typical example thereof is an aluminum thin film layer.

The polyester in the present invention includes ethylene terephthalate and ethylene α, β-bis (2-chlorophenoxy).
Ethane-4,4'-dicarboxylate, ethylene α, β
At least one structural unit selected from the group consisting of bis (phenoxy) ethane-4,4'-dicarboxylate and ethylene 2,6-naphthalate;

Among them, aromatic dicarboxylic acids such as terephthalic acid and isophthalic acid, adipic acid, and aliphatic dicarboxylic acids such as sebacic acid are used as the acid component, while ethylene glycol and diethylene glycol are used as the alcohol component.
Those having 1,4-butanediol or cyclohexanedimethanol are preferable. Particularly, when the melting energy of the polyester resin is 3 to 11 cal / g, the moldability of the polyester film is good and the adhesion is excellent even if the signal recording layer has irregularities, which is particularly preferable.

Further, when the average roughness of the surface of the metal thin film on the side of the polyester film is 0.05 μm or less, preferably 0.03 μm or less, the adhesion with the metal thin film is good, which is preferable.

The coating layer in the present invention has an average particle size of 0.11 to 0.70 μm.
Is a layer mainly composed of the inert inorganic particles and a water-soluble or water-dispersible resin. The main component means that itself occupies 70% by weight or more in the coating layer. As the inert inorganic particles in the present invention, titanium oxide, calcium carbonate, silicon oxide, lithium fluoride, calcium fluoride,
Examples thereof include mica and clay, and among them, inorganic colloids are particularly suitable.

The term “inorganic colloid” as used in the present invention is defined in the Kyoritsu Publishing Chemical Dictionary, and contains 10 ⁵ to 10 ⁹ atoms in one particle. Depending on the element, it is obtained as a metal colloid, an oxide colloid, or a hydroxide colloid. Metal colloids include gold, palladium, platinum,
Silver, sulfur, etc. are preferably used, oxide colloids,
Examples of hydroxide colloids, carbonate colloids, and sulfate colloids include oxide colloids of zinc, magnesium, silicon, calcium, aluminum, strontium, barium, zirconium, titanium, manganese, iron, cobalt, nickel, tin, and hydroxides. Material colloids, carbonate colloids, and sulfate colloids are preferably used in the present invention.
For example, a silicic acid colloid obtained by adding silicon tetrahalide to water or gradually adding concentrated hydrochloric acid to an aqueous solution of an alkali silicate is very preferably used in the present invention.

The average particle size of the inert inorganic particles is 0.11 to 0.70 μm, preferably 0.13 to 0.3 μm, more preferably 0.15 to 0.25 μm. When the average particle size is less than 0.11 μm, the biaxially stretched polyester film has insufficient lubricity, and wrinkles remain when it is bonded to the substrate, which significantly deteriorates the product yield, which is not preferable. On the other hand, if it is larger than 0.4 μm,
This is not preferable because the surface is easily scraped and the scraped powder is sandwiched between them when they are stuck together, which causes defects such as floating.

The average particle size here is measured using a centrifugal sedimentation type particle size distribution measuring device (SA-CP2 type manufactured by Shimadzu Corporation).

The water-soluble or water-dispersible resin in the present invention is not particularly limited, but as a typical one, a urethane resin,
An epoxy resin, a polyester resin, an acrylic resin, a vinyl resin, a silane resin, or a mixture thereof can be used regardless of thermoplasticity or thermosetting property.

However, as a resin that is particularly preferable among them, 0.5 to 15 mol% of all dicarboxylic acid components is a dicarboxylic acid that is a sulfonic acid metal group-containing dicarboxylic acid, and a water-soluble or water-dispersible polyester copolymerization consisting of a polyhydric alcohol,
A water-soluble or water-dispersible polyurethane whose affinity to water is enhanced by introducing a carboxylate group, a sulfonate group, or a sulfuric acid half-ester group, and a polyurethane such as an epoxy compound having two or more epoxy groups as necessary. Examples thereof include those to which a crosslinking substance has been added, and water-soluble or water-dispersible acrylics. Among them, those containing an alkyl acrylate or an alkyl methacrylate as a main component are preferable, and 30 to 90 mol% of the component and a vinyl monomer component 70 which is copolymerizable with these and has a functional group.
Water-soluble or water-dispersible resins containing -10 mol% are particularly preferred.

The vinyl monomer copolymerizable with alkyl acrylate or alkyl methacrylate and having a functional group includes a carboxyl group or a salt thereof, an acid anhydride group, a sulfonic acid group or a salt thereof, an amide group or an alkylolated amide group. , Amino groups (including substituted amino groups) or alkylolated amino groups or salts thereof, hydroxyl groups, epoxy groups and the like. Particularly preferred are a carboxyl group, a methylol group, an acid anhydride group, an epoxy group and the like. Two or more kinds of these groups may be contained in the resin.

When the mixing ratio of the alkyl acrylate and the alkyl methacrylate is 30/70 to 70/30, it is suitable from the viewpoint of the film formability and strength.

Examples of alkyl groups of alkyl acrylate and alkyl methacrylate include methyl group, ethyl group, n-
Examples thereof include propyl group, isopropyl group, n-butyl group, isobutyl group, t-butyl group, 2-ethylhexyl group, ularyl group, stearyl group and cyclohexyl group.

Examples of the compound having a carboxyl group or a salt thereof, or an acid anhydride group include acrylic acid, methacrylic acid, itaconic acid, maleic acid, fumaric acid, crotonic acid, metal salts of these carboxylic acids with sodium, ammonium salts, Alternatively, maleic anhydride and the like can be mentioned.

Examples of the compound having a sulfonic acid group or a salt thereof include vinyl sulfonic acid, styrene sulfonic acid, metal salts of these sulfonic acids with sodium, ammonium salts and the like.

Examples of the compound having an amide group or an alkylolated amide group include acrylamide, methacrylamide, N-methylmethacrylamide, methylolacrylamide, methylolmethacrylamide, ureido vinyl ether, β-ureidoisobutyl vinyl ether, and ureidoethyl acrylate. Can be mentioned.

Examples of the compound having an amino group or an alkylolated amino group or a salt thereof include diethylaminoethyl vinyl ether, 3-aminopropyl vinyl ether, 2-aminobutyl vinyl ether, dimethylaminoethyl methacrylate, dimethylaminoethyl vinyl ether and their amino groups. Examples thereof include methylolated products, alkyl halides, dimethylsulfate, and quaternary chlorides with sultone.

Examples of the compound having a hydroxyl group include β-hydroxyethyl acrylate, β-hydroxyethyl methacrylate, β-hydroxypropyl acrylate, β-hydroxypropyl methacrylate, β-hydroxy vinyl ether, 5-hydroxypentyl vinyl ether, 6-
Examples include hydroxyhexyl vinyl ether, polyethylene glycol monoacrylate, polyethylene glycol monomethacrylate, polypropylene glycol monoacrylate, and polypropylene glycol monomethacrylate.

Examples of the compound having an epoxy group include glycidyl acrylate and glycidyl methacrylate.

In addition to the above, the following compounds may be used in combination. That is, acrylonitrile, methacrylonitrile, styrenes, butyl vinyl ether, maleic acid mono- or dialkyl ester, fumaric acid mono- or dialkyl ester, itaconic acid mono- or dialkyl ester, methyl vinyl ketone, vinyl chloride, vinylidene chloride, vinyl acetate, vinyl Examples include, but are not limited to, pyridine, vinylpyrrolidone, vinyltrimethoxysilane, and the like.

The acrylic resin may contain a surfactant, but the low molecular weight surfactant contained in the acrylic resin is concentrated during the film formation process and is accumulated at the particle-particle interface or coated. When it moves to the interface of layers, problems may occur in the mechanical strength, water resistance, and adhesion to the laminate of the coating layer. In such a case, a so-called soap-free polymerized product containing no surfactant can be used.

However, among them, a copolymer of methyl methacrylate and ethyl acrylate of 35/65 to 65/35 (molar ratio) is used as a trunk polymer, and 1 to 5% by weight of -COOH and -CH ₂ OH ₂ are introduced to disperse water. Acrylic is particularly suitable for easy adhesion and transparency of the laminated film.

The concentration of inorganic colloid in the coating layer is 0.1-30% by weight
Is more preferable, more preferably 0.5 to 20% by weight, still more preferably 1.0 to 1.5% by weight. When the concentration of the inorganic colloid is less than 0.1% by weight, it is difficult to obtain a laminated film having desired slipperiness. If it exceeds 30% by weight, the transparency, easy adhesion and abrasion resistance of the laminated film are deteriorated and the adhesion of the coating layer to the base film is deteriorated, which is not preferable.

Further, in the coating layer, in order to improve the adhesion, water resistance, solvent resistance, and mechanical strength of the coating layer, a methylol- or alkylol-based urea-based melamine-based, acrylamide-based, or polyamide-based crosslinking agent is used. Resin, epoxy compound, aziridine compound, block polyisocyanate,
A reactive compound such as a vinyl compound may be contained. Further, if necessary, a defoaming agent, a coating property improving agent, a thickening agent, an antistatic agent, an antioxidant, an ultraviolet absorber, a dye, a pigment and the like may be added.

The polyester film constituting the film of the present invention,
It is at least biaxially oriented by a conventional method, and the thickness is preferably 2 to 600 μm, more preferably 5 to 450 μm, and excellent in handleability in practical use as a substrate base. Especially the biaxially stretched polyester film thickness is 75
-60 μm, preferably 250-600 μm, and when the melting energy of the polyester resin is 3-11 cal / g, the adhesion with the signal recording layer is improved, which is preferable.

The laminated thickness of the coating layer constituting the film of the present invention is not particularly limited, but is preferably 0.005 to 0.30 μm, and 0.01 to 0.10.
The range of μm is more preferable. If the layer thickness is less than 0.005 μm, not only is it difficult to achieve uniform layering, but also easy adhesion is reduced
Furthermore, the adhesive force of the inorganic colloid particles is reduced, and shavings are easily formed. On the other hand, if it exceeds 0.30 μm,
This is not preferable because the slipperiness and blocking resistance are insufficient.

The film of the present invention has a ratio (D / d) of the average particle diameter (D) of the inorganic colloidal particles of the coating layer to the coating layer thickness (d) of 1.1 to 80.
Must. It is preferably in the range of 2.0 to 40, more preferably 3.0 to 15. When the D / d is less than 1.1, the slipperiness of the laminated film is deteriorated, and adverse effects such as surface defects are increased, which is not preferable. When the ratio of particle diameter to film thickness exceeds 80, not only easy adhesion and smoothness are deteriorated, but also abrasion resistance of the coating layer is deteriorated and white powder is easily generated, which is a disadvantage after bonding, which is not preferable. .

Next, a typical method for producing the film of the present invention will be described, but the method is not limited thereto.

A composition (referred to as an optical recording medium in the present invention) in which a predetermined signal recording layer is provided on a predetermined base material is prepared. The optical recording material is not particularly limited to a disc-shaped material, a film-shaped material, a single-leaf material, and a continuous material, but a film-shaped material, particularly a continuous material is preferably used because the product becomes cheaper. The metal thin film layer (A), the polyester biaxially stretched film (B), and the coating layer (C) may be provided in this order on the signal recording layer side of the recording medium. The method is not particularly limited, but a typical method is used. The following methods can be mentioned. In the case of a write-once type recording medium, a dielectric layer made of SiO ₂ or a heat insulating layer made of CS ₂ or the like having a thickness of λ / 4n (where n is a positive integer) is provided on the recording layer of the recording medium, if necessary. After that, a reflective layer made of aluminum or the like is provided. On the other hand, when the recording layer having surface irregularities is provided in advance, the dielectric layer or the heat insulating layer is not particularly required, and a metal thin film such as aluminum may be provided directly on the recording layer.

An adhesive layer is not particularly required between the polyester biaxially stretched film (B) and the metal thin film, but it may be used as a matter of course. When an adhesive layer is used, it is preferable to use a film obtained by forming an adhesive layer on a base polyester film and then stretching the film uniaxially or more, because the adhesion is further improved.

The coating layer (C) is necessary for improving the handling property when the polyester biaxially stretched film and the recording medium are bonded together, and a predetermined polyester biaxially stretched film is subjected to bar coating, reverse coating, gravure coating, kiss coating, spray coating. Although it may be applied by a known method, it is most preferred to apply in the polyester biaxial stretching step from the viewpoint of wrinkles of polyester. Specifically, by coating the polyester film with the coating layer (C) and then stretching it at least uniaxially, the handling property not only when it is bonded to the recording medium but also when it is wound up is improved. It is more preferable. The laminated body thus obtained may be punched under predetermined conditions and cut into a predetermined shape by a method such as cutting. Further, it goes without saying that each layer having a predetermined shape may be laminated.

The method of measuring the characteristic value and the method of evaluating the effect of the present invention are as follows.

(1) Polyester film winding slitter of Nishimura Seisakusho, slit speed 350m /
In a minute, a film having a width of 1000 mm and a thickness of 25 μm was wound up for 6000 m, and its surface and end face were observed. If there are no small protrusions on the surface, "O" is "O", and other than that, "O" is "X". In addition, the end face was observed, and when there was no slack in the film circumference, "petals" were indicated as "○", and other parts were indicated as "x".

(2) Abrasion resistance A film is slit into a tape with a width of 1/2 inch, a single blade is pressed vertically, and the product is run for 20 cm while being pushed 0.5 mm (running tension: 500 g, running speed: 6.7 cm /
Seconds). At this time, the height of the shavings on the surface of the film attached to the tip of the single-edged blade was read with a microscope and used as the shaving amount (unit: μ
m). At least on one side, the abrasion resistance was evaluated as "⊚" when the scraped amount was 10 µm or less, the abrasion resistance was evaluated as "○" when the abrasion amount was 15 µm or less, and the abrasion resistance was evaluated as "x" when the abrasion amount exceeded 15 µm.

〔Example〕

 The present invention will be described based on examples.

Example 1 Intrinsic viscosity 0.6 using terephthalic acid as an acid component and ethylene glycol and 1,4-cyclohexanedimethanol as an alcohol component in a mixing ratio of 92 mol% to 8 mol%
5. A polyester copolymer having a melting energy of 6.8 cal / g (hereinafter abbreviated as "copolymerized polyester A") is dried under predetermined conditions. After melting the resin at 280 ° C, the surface temperature was 50
Extruded and molded on a drum at ℃. The unstretched film thus obtained is stretched 3.5 times in the longitudinal direction at 90 ° C.
Corona discharge treatment is applied to the surface of the obtained uniaxially stretched film, the following coating material is applied to one side of the film, and while being dried, stretched 3.5 times in the transverse direction at 110 ° C and then heat-treated at 220 ° C while being relaxed by 5%. A film having a thickness of 25 μm was obtained. The coating layer on the film had a thickness of 0.04 μm. As the paint, methyl methacrylate and butyl acrylate 1:
A coating prepared by adding 4% by weight of colloidal silicon oxide having an average particle size of 0.13 μm to the coating prepared by introducing 2.5 mol% of -CH ₂ OH and -COOH into the copolymer of 1 to make it hydrophilic was used. Table 1 shows the results of evaluation of the films thus obtained.

Example 2 Instead of colloidal silicon oxide having an average particle size of 0.13 μm,
The same procedure as in Example 1 was carried out except that colloidal silicon oxide having an average particle size of 0.20 μm was used. The results are shown in Table 1.

Example 3 Instead of colloidal silicon oxide having an average particle size of 0.13 μm,
Example 1 was repeated except that colloidal silicon oxide having an average particle size of 0.40 μm was used. The results are shown in Table 1.

Example 4 Instead of colloidal silicon oxide having an average particle size of 0.13 μm,
The same procedure as in Example 1 was carried out except that colloidal silicon oxide having an average particle size of 0.60 μm was used. The results are shown in Table 1.

Comparative Example 1 Instead of colloidal silicon oxide having an average particle size of 0.13 μm,
Example 1 was repeated except that colloidal silicon oxide having an average particle size of 0.03 μm was used. The results are shown in Table 1.

Comparative Example 2 Instead of colloidal silicon oxide having an average particle size of 0.13 μm,
The same procedure as in Example 1 was carried out except that colloidal silicon oxide having an average particle diameter of 1.00 μm was used. The results are shown in Table 1.

Example 5 Example 5 was carried out in the same manner as in Example 1 except that colloidal silicon oxide having an average particle diameter of 0.25 μm was used instead of colloidal silicon oxide having an average particle diameter of 0.13 μm, and the coating layer had a thickness of 0.01 μm. . The results are shown in Table 1.

Comparative Example 3 Instead of colloidal silicon oxide having an average particle size of 0.13 μm,
Example 1 was repeated except that colloidal silicon oxide having an average particle size of 4.00 μm was used. The results are shown in Table 1.

Example 6 Example 6 except that colloidal silicon oxide having an average particle size of 0.40 μm was used in place of colloidal silicon oxide having an average particle size of 0.13 μm, and 0.06% by weight of silicon oxide particles was added to the copolyester A. The same procedure as in 1 was performed. First result
Shown in the table.

Example 7 The procedure of Example 3 was repeated, except that polyethylene terephthalate having an intrinsic viscosity of 0.65 and a melting energy of 13 cal / g was used in place of the copolymerized polyester A. The results are shown in Table 1.

As can be seen from the table, in the range of the present invention, excellent properties suitable for optical recording media are exhibited.

In addition, Example 3 and Comparative Example 2 in which a non-coated surface of a polycarbonate having an uneven surface in advance was vapor-deposited with aluminum
When the films of No. 1 and No. 3 were attached, it was possible to adhere an aluminum vapor deposition layer having no pinholes in the case of Example 3, but in the case of Comparative Example 2, many pinholes were observed in the vapor deposition layer and at the same time, foreign matter was generated. Since it was sandwiched between them, there were places where the adhesion was insufficient, so sufficient recording reproducibility could not be obtained, and it was unsuitable.

[Effects of the Invention] Since the present invention has such a layer structure, the following excellent effects can be obtained.

That is, it became possible to obtain excellent abrasion resistance and slipperiness while maintaining the surface smoothness of the polyester film. As a result, it has become possible to expect an improvement in product yield.

Claims (4)

(57) [Claims] 1. An optical recording medium for recording information signals such as video, audio, characters, etc. at high density, from a laminate in which a signal recording layer, a metal thin film layer, a polyester biaxially stretched film and a coating layer are laminated in this order. And the coating layer has an average particle size of 0.11
To 0.70 μm of inert inorganic particles and a water-soluble or water-dispersible resin as a main component, and the ratio (D / d) of the average particle diameter (D) of the inert inorganic particles to the thickness (d) of the coating layer. The optical recording medium is characterized in that 2. The optical recording medium according to claim 1, wherein the center line average roughness of the metal thin film layer side surface of the polyester biaxially stretched film is 0.02 μm or less. 3. The melting energy of the polyester biaxially stretched film is 3 to 11 cal / g.
Or the optical recording medium of 2. 4. The optical recording medium according to claim 1, 2 or 3, wherein the coating layer is stretched in at least a uniaxial direction.