JPH0315262B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to high performance video or audio disk substrates, particularly optical video or audio disk substrates. BACKGROUND OF THE INVENTION Due to advances in optical technology, information recording media such as video discs and audio discs using large capacity recording and reproducing technology are a field that has rapidly developed in recent years. As for the construction method of a disk, the form and each component material have been studied from various aspects, and there are a wide variety of methods, but as a general example of an optical disk, the three main layers of the substrate, the information recording layer, and the light reflection layer are used. For example, a transparent synthetic resin sheet or film is often used as the substrate due to its light weight and ease of handling. but,
These synthetic resin sheets and film substrates have poor surface abrasion resistance, are easily scratched during disk manufacturing and handling, and generate noise that may cause recording problems.
It has a major drawback in that playback performance tends to deteriorate. Various studies have been carried out to improve these shortcomings, such as providing a transparent layer with a depth of focus greater than the depth of focus of the optical system between the photosensitive layer, that is, the information recording layer, and the substrate, and providing a wear-resistant protective layer on the surface of the substrate. Methods for providing such information have been proposed. However, a mere ordinary transparent coating layer has completely insufficient scratch resistance, and even conventional wear-resistant protective layers do not necessarily have sufficient scratch resistance. Moreover, since these are essentially cross-linked cured films, a drawback has been recognized that the adhesion with the information recording layer is reduced. The present invention improves the drawbacks of these conventional methods and provides a novel video or audio disk substrate that has excellent scratch resistance and adhesion to the information recording layer, and is smooth and suitable for precise recording and reproduction of information. The main purpose is to That is, the present invention is a substrate for a video or audio disk, which is formed by forming a (meth)acrylic cured film made of a specific component on the surface of a synthetic resin disk. The synthetic resin disc used in the present invention may be a known methacrylic resin disc such as polymethyl methacrylate or methyl methacrylate copolymer, or a known vinyl chloride disc such as polyvinyl chloride or vinyl chloride copolymer. A resin plate is preferably used, and a methacrylic resin plate is most preferable from the viewpoint of transparency. However, transparent sheets and films made of polystyrene, styrene copolymer, polyester, polycarbonate, etc. can also be used as the synthetic resin plate of the present invention. The (meth)acrylate-based curing liquid applied to the synthetic resin board needs to be crosslinked and cured by active energy rays. Generally, a method for forming a wear-resistant protective layer is to apply a silicone-based, melamine-based, or urethane-based coating material to a synthetic resin plate and heat cure it, but these methods require high-temperature, long-term curing. This method is unsuitable as a surface treatment method for a resin plate for information disks, which particularly requires smoothness, since the productivity is poor and the resin plate is deformed by heating. In this point,
A photocuring method using active energy rays is preferable because it causes less thermal deformation, but regardless of whether it is a thermocuring method or a photocuring method, the cured film by the conventional method is a crosslinked film, so both lipophilic and new water-based compounds have poor wettability. Furthermore, when applying a photosensitive resin to form an information recording layer on the surface of the cured film, it is difficult to apply it uniformly and the adhesion is poor, making the disc unusable. Summer. Of course, adhesion can be improved by reducing the crosslinking density of the cured film, but in this case, as with general paints, the scratch resistance will be greatly reduced, and scratches that will cause noise when playing the disc will occur. will be invited. In contrast, by using a specific (meth)acrylate compound, the curing liquid of the present invention is rapidly crosslinked and cured in a short time by irradiation with active energy rays in the air, forming a cured film with extremely excellent scratch resistance. Moreover, it exhibits a completely unique behavior in that it is possible to further coat and form an information recording layer on the cured film while maintaining uniform and strong adhesion. The cured film of the present invention contains 30 to 90 parts by weight of a polyfunctional monomer (a) having three or more (meth)acryloyloxy groups per molecule, at least one ether bond per molecule, Mono- to difunctional (meth)acrylate (b ₁ ) having a boiling point of 150°C or higher at normal pressure and a viscosity of 20 centipoise or lower at 20°C 9.5
~69.5 parts by weight and 0.5 to 10 parts by weight of an alkyl (meth)acrylate homopolymer or copolymer (b ₂ ) having an intrinsic viscosity of 0.01 to 0.3/g and an alkyl group having 1 to 8 carbon atoms Monomer mixture (A) consisting of
20 to 80 parts by weight of at least one organic solvent that can be mixed with the mixture (A) to form a homogeneous solution;
It can be formed by applying a composition containing 90 parts by weight to the surface of a synthetic resin plate and irradiating it with active energy rays, preferably in the air. The polyfunctional monomer (a) having three or more (meth)acryloyloxy groups per molecule used in the present invention refers to a polyhydric alcohol with a valence of 3 or more, or a derivative thereof, (meth)acrylic acid, or these. A crosslinkable monomer obtained by reacting an acid with a halide or ester, such as trimethylolpropane tri(meth)acrylate, pentaglycerol tri(meth)acrylate, pentaerythritol tetra Examples include (meth)acrylate. Such polyfunctional monomers are the main components that form a cross-linked cured film when irradiated with active energy rays, but some of them, when irradiated in air, undergo a cross-linking and curing reaction due to oxygen in the air. Some of them are suppressed and do not exhibit sufficient wear resistance. In such cases, it is necessary to perform the irradiation in an inert gas atmosphere such as nitrogen gas or carbon dioxide gas. Since this is disadvantageous in practice due to the complexity of the working process, it is more preferable to use a monomer that can form a crosslinked cured film having sufficient abrasion resistance by irradiation in the air in carrying out the present invention. A polyfunctional monomer that satisfies this condition has the following general formula: (In the formula, X ₁₁ , X ₁₂ , X ₁₃ , X ₂₂ , X ₂₃ ..., X _o2 ,
At least three of X _o3 and X ₁₄ are CH ₂ = CR ₇ −
The COO group and the rest are -OH groups. n is an integer from 2 to 5. R ₇ is hydrogen or a methyl group. ) Polypentaerythritol poly(meth)acrylate is mentioned. It has very good polymerization activity upon irradiation with active energy rays and is crosslinked and cured to form a polymer exhibiting a high degree of wear resistance. Specific examples include pentaerythritol tri(meth)acrylate, pentaerythritol tetra(meth)acrylate,
Examples include dipentaerythritol tetol (meth)acrylate, dipentaerythritol penta(meth)acrylate, dipentaerythritol hexa(meth)acrylate, and the like. Two or more of the above polyfunctional monomers can also be used in combination. The amount of polyfunctional monomer used is 30 to 90 parts by weight. If it is less than 30 parts by weight, the surface hardness and scratch resistance of the cured film will be insufficient, while if it exceeds 90 parts by weight, the smoothness of the cured film will be insufficient. Sexuality becomes insufficient. It also has at least one ether bond in one molecule that can be copolymerized with the polyfunctional monomer (a), has a boiling point of 150°C or higher at normal pressure, and has a viscosity of 20 centipoise or lower at 20°C. Examples of the monofunctional (meth)acrylate (b ₁ ) include 2-ethoxyethyl (meth)acrylate, 3-ethoxypropyl (meth)acrylate, 2-butoxyethyl (meth)acrylate, phenoxyethyl (meth)acrylate,
2-(2-methoxyethoxy)-ethyl (meth)acrylate, 2-(2-ethoxyethoxy)-ethyl (meth)acrylate, tetrahydrofurfuryl (meth)acrylate, 2-tetrahydrofurfuryloxyethyl (meth)acrylate, 2 -Glycidyloxyethyl (meth)acrylate and the like. These are preferred components from the viewpoint of air oxidation properties and coating film smoothness. Monofunctional (meth)acrylate (b ₁ ) has the above properties, but has a boiling point of 150 at normal pressure.
If the temperature is less than 0.degree. C., the monomer will easily volatilize, causing environmental problems, and compositional changes will likely occur. Furthermore, if the viscosity exceeds 20 centipoise, the smoothness of the cured film will be insufficient. The component (b ₁ ) has an ether bond, and a monomer having an ether bond in the molecule is preferable because it has good UV curability in air. In addition, the amount of component ( _b1 ) used is 9.5 to 69.5 parts by weight, but if it is less than 9.5 parts by weight, the smoothness of the cured film will be insufficient, and if it exceeds 69.5 parts by weight, the surface hardness and scratch resistance of the cured film will be becomes insufficient. Examples of those with two (meth)acryloyloxy groups per molecule include glycol di(meth)acrylate, polyalkylene glycol di(meth)
Examples include diethylenically unsaturated compounds such as acrylates. Examples of compounds that are highly curable in air include those represented by the following general formula, specifically 2,2-bis(4-acryloyloxyphenyl)propane, 2,2-bis( 4
-acryloyloxyethoxyphenyl)propane, 2,2-bis(4-acryloyloxyethoxyphenyl)propane, 2,2-bis(4-acryloyloxypropoxyphenyl)propane, 2,2-bis[4-acryloyl Oxy (2
-Hydroxypropoxy)phenyl]propane, etc. These are effective in imparting flexibility and adhesion to the resin plate to the cured film. (In the formula, X ₁ , X _{2 .} . . Intrinsic viscosity is 0.01 to 0.01 along with (b ₁ ) component.
0.3/g, and the number of carbon atoms in the alkyl group is 1 to 8
The combined use of the alkyl (meth)acrylate homopolymer or copolymer (b ₂ ) component is particularly effective for improving the adhesion to the substrate. When the number of carbon atoms in the alkyl group of component (b ₂ ) exceeds 8, the glass transition temperature of the polymer decreases, causing problems in handling. The amount used is 0.5 to 10 parts by weight, but if it is less than 0.5 parts by weight, the effect of improving adhesion will be small.
If it exceeds 10 parts by weight, the surface hardness and scratch resistance of the cured film will be insufficient. In addition, in order to impart excellent antifogging and antistatic properties to the crosslinked cured film, the following general formula is added to the above mixture (A). (In the formula, R ₁ is hydrogen or a methyl group, and Y is -
It is a CONH group or a -COO group, and l, m, n and r are integers of 0 to 5. ) Sulfonic acid monomer (C) represented by and/or the following general formula (In the formula, R ₂ is hydrogen or a methyl group, and R ₃ is hydrogen or

[Formula] group, R ₄ is hydrogen or a methyl group, and m and n are integers of 1 to 15. ) 0.5 to 20 parts by weight of a phosphoric acid ester monomer (d) represented by the following general formula NR ₅ R ₆ (CH ₂ CH ₂ OH) (wherein R ₅ and R ₆ are hydrogen and the number of carbon atoms 1 to 15 alkyl groups or CH ₂ CH ₂ OH groups.) 1 to 20 parts by weight of the ethanolamine compound (e) can be added. The sulfonic acid monomer (c) used in the present invention is a sulfoalkyl ester of an unsaturated monocarboxylic acid having a double bond or an acid amide thereof, and specific examples thereof include sulfoethyl (meth)acrylate,
Sulfoprokyl (meth)acrylate, sulfobutyl (meth)acrylate, sulfoethyl vinyl acetate, sulfopropyl vinyl acetate,
Sulfopropyl vinyl propionate, 2-acrylamido-2-methylpropanesulfonic acid, 2
-Methacrylamide-2-methylpropanesulfonic acid, 3-acrylamido-3-methylbutanesulfonic acid, and the like. The phosphate ester monomer (d) has at least one (meth)acryloyloxy group, and specific examples include (meth)acryloyloxyethyl phosphate and di(meth)acryloyloxyethyl phosphate. ate, (meth)acryloyloxypropyl phosphate, (meth)acryloyloxybutyl phosphate, and the like. Other compounds that do not have a (meth)acryloyloxy group, such as halogenated vinyl phosphates and alkyl-substituted vinyl phosphates,
This is not preferred because it inhibits curing in air. The ethanolamine compound (e) is an alkylamine having at least one -CH ₂ CH ₂ OH group in one molecule, and the N-substituted alkyl group has 1 to 1 carbon atoms.
A value of 15 is suitable, and a value exceeding 15 is not preferred because the hardness of the coating decreases. Specific examples include ethanolamine, β-ethylhexylethanolamine, diethanolamine, N-butylethanolamine, N-hexyldiethanolamine, N-
-lauryldiethanolamine, N-cetyldiethanolamine, triethanolamine, etc. Although these components (c), (d) and (e) can be used to carry out the present invention without adding them, a crosslinked film with excellent abrasion resistance can be obtained; however, when these components are added, the cured film has antistatic properties. , anti-fog properties can be imparted. In general, synthetic resin plates have strong electrostatic properties regardless of the presence or absence of a cured film, tend to attract foreign matter and dust, and are water repellent, so they tend to become cloudy due to moisture. These are undesirable because they cause light scattering like scratches on the surface of the resin plate and reduce recording and reproduction accuracy. For this reason, antistatic agents and antifogging agents are usually kneaded into the resin of the information disk or applied to the surface of the information disk, but these lack durability and, if used for a long time, the additives may leach, agglomerate, or precipitate. etc., will cause light scattering. In this regard, in the present invention, components (c) and (d) are polymerized and fixed during curing, and
Component (e) has good durability because it is reacted and fixed with components (c) and/or (d). Note that component (e) is preferably blended in combination with component (c) and/or (d), and a remarkable synergistic effect can be obtained even when added in a small amount.
In particular, since component (c) lacks compatibility with other components in the curing liquid, it is particularly desirable to use component (e) in combination. Monomer mixture constituting the coating composition of the present invention
The organic solvent (B) used in combination with (A) has extremely favorable effects on workability, uniform coating film formation, and storage stability when coating the coating composition on the surface of a synthetic resin board. , is also used to increase the adhesion of the crosslinked cured coating to the resin plate. The organic solvent used in the present invention is (1) mixed with the polyfunctional (meth)acrylate monomer mixture (A) to form a homogeneous solution. (2) The boiling point at normal pressure is 50°C or higher and 200°C or lower, (3) The viscosity at normal temperature is 10 centipoise or lower. Specifically, alcohols such as ethanol, isopropanol, n-propanol, isobutyl alcohol, and n-butyl alcohol, aromatic hydrocarbons such as benzene, toluene, xylene, and ethylbenzene, ketones such as acetone and methyl ethyl ketone, and ethers such as dioxane. , ethyl acetate, n-butyl acetate, ethyl propionate, and other acid esters, N,N-dimethylformamide, and the like. One type of these organic solvents may be used alone, or two or more types may be used in combination as long as the boiling point and component ratio of the mixture are within the range that satisfies the above-mentioned requirements. To apply the above-mentioned curing liquid to the substrate, any of the usual coating methods such as casting, spraying, rotation, and dipping can be applied, but especially for information disks that require uniform and smooth coating film formation. The dipping method and the rotating method are most suitable for the substrate. The film thickness is selected depending on the optical system used to reproduce information, but if it is too thick, cracks will occur and the smoothness will decrease, and if it is too thin, the hardness will decrease, so the depth of focus of the optical system should also be taken into consideration. -30μ, preferably 3-10μ. Applying the curing liquid of the present invention to the surface of a synthetic resin board,
In order to form a crosslinked cured film, it is necessary to irradiate with active energy rays such as ultraviolet rays, electron beams, or radiation. Among these, the method using ultraviolet irradiation is the most preferred from a practical standpoint. When using ultraviolet rays, the curing speed can be increased by adding a photosensitizer to the curing solution that initiates the polymerization reaction of monomers upon irradiation with ultraviolet rays. Specific examples of such photosensitizers include benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, acetoin, butyroin, toluoin, benzyl, benzophenone, P-chlorobenzophenone, P-methoxybenzophenone. carbonyl compounds such as, sulfur compounds such as tetramethylthiuram monosulfide and tetramethylthiuram disulfide, azo compounds such as azobisisobutyronitrile and azobis-2,4-dimethylvaleronitrile, benzoyl peroxide, ditertiary - Peroxide compounds such as butyl peroxide and the like can be mentioned. The amount of photosensitizer to be blended is preferably 0.01 to 10 parts by weight per 100 parts by weight of the curing liquid.
These photosensitizers may be used alone or in combination with
You may use it in combination of more than one kind. The above-mentioned curing liquid can be cured even in an inert atmosphere such as nitrogen, and a cured film having a somewhat better balance of performance can be obtained compared to conventionally known curing liquids, but it is uneconomical and particularly difficult for the information recording layer. It is preferable to cure in air because of poor adhesion. An information recording body can be obtained by pressing one side of the synthetic resin plate of the present invention with a cured film formed on the surface thereof using a matrix under heating using the usual method for manufacturing information discs. Due to the good heat resistance of the cured film, this method allows for higher heating than normal press molding, which softens the cured film and improves the fluidity of the base resin, making it easier to transfer fine signals. Not only is this easier, but the shape of the signal formed from the resin becomes sharper after cooling. However, in order to accurately transfer the signals engraved on the surface of the matrix, fluid molding resin is provided on one side of the synthetic resin plate, the matrix is placed on top of this fluid molding resin, and then the synthetic resin plate is placed on the other side. Advantageously, the fluid molding resin is cured by irradiation with active energy radiation through the irradiation. A more detailed process on this point can be found in JP-A-Sho.
It is also disclosed in 53-86756 and 53-116105. As the fluid molding resin in the present invention, it is also possible to use the above-mentioned curing liquid as is, or a radiation-curable resin such as a photopolymerizable gas monomer such as fluorescein or varylene vapor, or a mixture of a trithiol compound and a triene compound. Liquid lacquer and the like may also be used. In particular, in order to fully demonstrate the effects of the present invention,
A radiation-curable compound containing a liquid mixture of low molecular weight mono-, di-, tri- or tetra-esters of (meth)acrylic acid is preferred from the viewpoint of adhesion to the synthetic resin plate. Specific examples include alkyl (meth)acrylate, phenyl (meth)acrylate, alkoxy (meth)acrylate, alkylene glycol di(meth)acrylate, polyalkylene glycol di(meth)acrylate, trimethylolpropane tri(meth)acrylate,
Examples include polyester (meth)acrylate, urethane (meth)acrylate, and epoxy (meth)acrylate, and these may be used alone or as a mixture. When the above fluid molding resin is applied onto a synthetic resin plate in the usual manner, a matrix is applied, and active energy rays are irradiated through the synthetic resin plate, the fluid molding resin hardens and the recording signal on the surface of the matrix is transferred. Ru. As a method for applying the fluid molding resin, a rotation method is suitable from the viewpoint of the accuracy of the obtained film thickness. It is advantageous to remove the synthetic resin plate from which signals have been transferred, that is, to record information, from the matrix, and to further form a light-reflecting layer of aluminum or the like on its surface by vapor deposition. Further, if necessary, a suitable protective layer may be provided on the light reflecting layer, or the protective layers of two disks (information recording bodies) may be bonded together to be used as a set of disks. In this way, the outer layers on both sides of the information recording medium are protected by the scratch-resistant cured film, and the effects of the present invention are most effectively exhibited. The present invention can also be fully applied to an information recording medium in which information is reproduced using transmitted light, and in this case, it is preferable to form a scratch-resistant cured film using the curing liquid of the present invention instead of the light-reflecting layer. It's advantageous. The present invention will be explained in more detail with reference to Examples below. Examples 1 to 3 and Comparative Examples to 15 Various curing solutions shown in Table 1 were prepared, and a 1.5 mm thick polymethyl methacrylate resin plate (Acrylite L manufactured by Mitsubishi Rayon) was immersed in the above curing solution and pulled up. A film was formed on both sides. After leaving it for 1 minute, ultraviolet rays were irradiated on both sides of the plate for 10 seconds from a distance of 20 cm using a 2KW high-pressure mercury lamp in a predetermined atmosphere to form a cured film layer of about 4μ. Furthermore, 8 parts by weight of methyl methacrylate and trimethylolpropane triacrylate were added on one surface of the cured film layer.
A fluid molding resin consisting of 20 parts by weight and 2 parts by weight of benzoin isobutyl ether was applied by spin, and a flat disc matrix made of an aluminum plate with a diameter of 30 cm was placed on top of this, from a distance of 20 cm from the cured film surface on the opposite side.
A 2KW high-pressure mercury lamp was irradiated for 60 seconds. After removing the flat disc matrix, a light reflective layer of aluminum with a thickness of approximately 350 Å was provided on the hardened fluid molded resin by vacuum deposition to produce a single-sided information recording disc. Table of evaluation results of various performances along with comparative examples.
1. Shown in Table-2. (1) Scratch resistance a Measured according to pencil hardness JIS K5651-1966. b Steel wool method Attach #000 steel wool to the tip of a cylinder with a diameter of 25 mm, bring the sample surface placed horizontally into contact with it, rotate it 5 times at a load of 300 g at 20 rpm, visually judge the degree of scratches, and evaluate it according to the following criteria. evaluated. A: No scratches B: Slight scratches C: Obvious scratches D: Significant scratches (2) Adhesion Both cured film and photosensitive film were evaluated using a cross-cut cellophane tape peel test. did. Insert 11 film cutting lines in the vertical and horizontal directions that reach the base material at 1 mm intervals on the film, making 100 ¹ mm squares, then press cellophane tape on top of it, then peel it off sharply in a 90 degree direction and compare. , evaluated based on the following criteria. ○ Number of peelings 0 △ 〃 1 to 50 pieces × 〃 51 to 100 pieces (3) Surface foreign matter Observe the state of foreign matter on the disk surface with a microscope,
Compared to using a substrate without surface treatment,
Evaluation was made based on the following criteria. ++ Foreign substances significantly decreased + Slightly decreased ○ Almost unchanged − Slightly increased

【table】

【table】

[Table] Modified with methacrylic acid.

【table】

Claims (1)

[Scope of Claims] 1. 30 to 90 parts by weight of a polyfunctional monomer (a) having three or more (meth)acryloyloxy groups per molecule, at least It has one ether bond and has a boiling point of 150 at normal pressure.
9.5 to 69.5 parts by weight of a mono- or difunctional (meth)acrylate (b ₁ ) having a viscosity of 20 centipoise or less at 20 °C or higher and an intrinsic viscosity of 0.01 to 0.3
/g, and a monomer mixture (A) consisting of 0.5 to 10 parts by weight of an alkyl (meth)acrylate homopolymer or copolymer (b ₂ ) in which the alkyl group has 1 to 8 carbon atoms is cured. A video or audio disk substrate formed by a cured film. 2. The cured film further comprises the following general formula in addition to the monomer mixture (A) according to claim 1: (In the formula, R ₁ is hydrogen or a methyl group, and Y is -
It is a CONH group or a -COO group, and l, m, n and r are integers of 0 to 5. ) Sulfonic acid monomer (C) represented by and/or the following general formula (In the formula, R ₂ is hydrogen or a methyl group, R ₃ is hydrogen or a [Formula] group, R ₄ is hydrogen or a methyl group, and m and n are integers from 1 to 15.) 0.5 to 20 parts by weight of the phosphoric acid ester monomer (d) shown below and the general formula NR ₅ R ₆ (CH ₂ CH ₂ OH) (wherein R ₅ and R ₆ are hydrogen and have 1 to 1 carbon atoms) 15 alkyl group or -CH ₂ CH ₂ OH group. The video or audio disc substrate according to item 1. 3 Polyfunctional monomer (a) has the following general formula (In the formula, _X11 , _X12 , _X13 , _X22 , _X23 ...X _o2 ,
At least three of X _o3 X ₁₄ are (meth)acryloyloxy groups, the rest are hydroxyl groups, and n is 1
3. The video or audio disk substrate according to claim 1 or 2, which is polypentaerythritol represented by: