JP2009151918A - Information recording medium and method of manufacturing information recording medium - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an information recording medium having a print receiving layer which is hardly damaged, while having extremely high color developability, high gloss and high driability, and is formed from a print receiving layer-coating liquid having good handling properties, and to provide a method of manufacturing the information recording medium. <P>SOLUTION: In the information recording medium I having a substrate 10, and at least an optical information recording layer 11, a base layer 14 and the print receiving layer 15 formed on the substrate 10, the base layer 14 contains not more than 2.6% by mass of an antifoaming agent or a leveling agent, and the print receiving layer 15 is composed of a porous layer mainly containing inorganic fine particles having an average secondary particle diameter of ≤500 nm and a polyvinyl alcohol. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an information recording medium and the like, and more particularly to an information recording medium and the like having a print receiving layer.

  Currently, there are CD (Compact Disk) and DVD (Digital Versatile Disk) as information recording media having an optical information recording layer that is widely accepted in the market, optically records information, and can be read. Both CD and DVD are read-only CD-ROM, DVD-ROM, write-once type CD-R, DVD-R, DVD + R capable of recording information only once, rewritable type capable of rewriting information recording any number of times CD-RW, DVD-RW, DVD + RW, and DVD-RAM. In recent years, Blu-ray Disc (BD) and HD-DVD discs, which are large-capacity recording media using a blue laser with a short wavelength in order to perform higher density recording, have begun to be put into practical use.

In order to facilitate classification and storage, or to make it easy to confirm the data contents, these information recording media are printed on the label surface of the information recording medium (by applying light). In some cases, a content display or the like is printed on the surface opposite to the surface on which information is recorded.
However, in the case of the existing printing method, it is necessary to make a printing plate for printing in small-volume production, which increases the cost, and it is necessary to perform color matching by replacing the printing plate each time the printing design is changed. For example, there are problems that workability deteriorates.

  In response to such a problem, an information recording medium in which a print receiving layer that can be printed by an ink jet printer or a sublimation thermal transfer printer is coated on the label surface of the information recording medium has been developed and marketed. In addition to the information recording medium provided with such a printable print receiving layer, Patent Document 1 discloses a method for printing on a label and then affixing the information recording medium for an inkjet printer. Yes. However, this method is very complicated in alignment of labels.

Therefore, in recent years, many inexpensive models that can print directly on an information recording medium have been released. Inkjet-printable information recording media are very easy to produce, and are becoming widespread not only for business use but also for home use.
As a print receiving layer of such an ink jet printable information recording medium, for example, in Patent Document 2 to Patent Document 8, an ultraviolet curable resin as a main component, or an ultraviolet curable resin and an ink swellable resin are used in combination. Mixed recipes are used.
Patent Document 3 reports a print-receiving layer in which the drying property of ink is improved by using a large amount of pigment particles.
Patent Document 9 proposes a print-receiving layer comprising a hydrophilic resin such as polyvinyl alcohol or polyvinyl acetal as a main component and a cationic polymer mixed as an ink fixing agent.

Patent Documents 10 to 13 propose a print receiving layer containing at least fine particles, polyvinyl alcohol, a boron compound, and a mordant, and gas phase method silica, pseudoboehmite, and aluminum oxide are suitable as the fine particles. Is described.
Further, Patent Document 14 proposes an optical information recording medium having a porous layer made of a resin film containing a vapor phase inorganic powder such as vapor phase method alumina.
In addition, silica synthesized by a wet method (hereinafter referred to as wet method silica) is also used, and the present inventors mainly have a print containing wet method silica and polyvinyl alcohol pulverized to an average secondary particle diameter of 500 nm or less. An information recording medium having a receiving layer was reported (see Patent Document 15).

Japanese Patent Laid-Open No. 5-182411 JP 2004-234664 A JP 2004-030716 A JP 2004-030769 A JP-T-2004-503610 JP 2001-006225 A Japanese Patent Application Laid-Open No. 08-279179 JP 09-245380 A JP-A-2005-44478 JP 2004-276298 A JP 2004-276299 A Japanese Patent Laying-Open No. 2005-096258 JP 2005-116072 A JP 2006-260748 A JP 2007-076007 A

  However, the print receiving layer reported in Patent Documents 2 to 8 is a swelling type that absorbs ink mainly by utilizing the swelling of the ink-swellable resin. In the case of such a swelling type, the so-called ink drying property is insufficient as compared with the ink-jet recording material for photographic printing, which is a void type that absorbs ink by the capillary phenomenon of fine voids in recent years. For this reason, after printing, there are problems such as an image or a finger becoming dirty when the printing part is touched with a finger, and sticking to an index when it is stored in a case together with the index. Further, in a commercial duplication system, there are cases where several tens to several hundreds of sheets are continuously printed. In that case, there is a problem that the media stacked on the tray after printing are blocked.

Next, when many pigment particles are used as exemplified in Patent Document 3, there are problems such as deterioration of adhesion to the substrate, color development and glossiness. . Further, these ultraviolet curable resins have problems of safety and workability such as skin irritation and off-flavor.
In addition, as reported in Patent Document 9, when a hydrophilic resin is used as a main component, there is no problem of safety and workability, but because of the swelling type, the drying property is insufficient.

  On the other hand, as reported in Patent Document 10 to Patent Document 13 and Patent Document 14, silica synthesized by a vapor phase method (hereinafter referred to as vapor phase method silica) is also used. In addition, when aluminum oxide is used, there is no problem of safety and workability, and color development, gloss, and drying are improved. However, since the vapor phase silica has a three-dimensional stitch structure of primary particles, the stability over time is low, and when used for a long period of time, there is a problem that the handling property is remarkably deteriorated because the viscosity of the coating solution increases. In addition, when pseudoboehmite or aluminum oxide is used, the stability over time is low as in the case of the vapor phase method silica, and not only the handling property is significantly deteriorated due to an increase in the viscosity of the coating solution, but also when the label surface is printed on a printer or in actuality. There is also a problem that fingers and nails are easily damaged when using the drive.

Furthermore, even if an information recording medium having a print receiving layer containing wet-process silica and polyvinyl alcohol reported in Patent Document 15 is used, the color developability may be relatively low depending on the type of ink used depending on the label printer. .
Therefore, there is a demand for an information recording medium that has a very high color developability in all label printers, is hardly damaged, and has a good coating liquid handling property at the time of production.

  Accordingly, an object of the present invention is to provide an information recording medium having a very high color developability, high gloss and drying properties, less scratching, and good handling properties of the print receiving layer coating solution, and a method for producing the same. It is to provide.

Thus, according to the present invention, the following (1) to (7) are provided.
(1) It has at least an optical information recording layer, an underlayer and a print receiving layer on the substrate, and the underlayer contains 2.6% by mass or less of an antifoaming agent or a leveling agent. The print receiving layer is a porous layer containing inorganic fine particles having an average secondary particle diameter of 500 nm or less as main components and polyvinyl alcohol.
(2) The inorganic fine particles include wet-process silica (A) pulverized to an average secondary particle diameter of 500 nm or less and vapor-phase process silica (B) having an average primary particle diameter of 10 nm to 20 nm. B) = (70/30) to (30/70) The information recording medium according to (1), which is contained at a mass ratio.
(3) The information recording medium according to (1) or (2), wherein the print receiving layer contains a water-soluble polyvalent metal.
(4) An information recording medium manufacturing method according to any one of (1) to (3), wherein the print receiving layer is formed on the underlayer by spin coating. Production method.
(5) The print receiving layer is formed by the spin coating method in an environment where the exhaust air velocity from the center of the information recording medium to the outer peripheral direction is 4 m / s or more at the outer periphery of the information recording medium. (4) The method for producing an information recording medium according to (4).
(6) A substrate, an optical information recording layer formed on the substrate directly or via another layer, and formed directly or via another layer on the side opposite to the laser beam incident side of the substrate. A base layer and a print receiving layer, wherein the base layer contains an antifoaming agent or a leveling agent in a range of 0.1% by mass to 2.6% by mass, and the print receiving layer is a main component An information recording medium comprising a porous layer containing inorganic fine particles having an average secondary particle diameter of 20 nm to 500 nm and polyvinyl alcohol.
(7) A substrate, and at least an optical information recording layer and a print receiving layer on the substrate, wherein the print receiving layer contains inorganic fine particles having an average secondary particle diameter of 500 nm or less and polyvinyl alcohol. A method for producing an information recording medium, characterized in that the print receiving layer has an exhaust air velocity of 4 m / mm from the center of the information recording medium to the outer periphery in the outer periphery of the information recording medium. A method for producing an information recording medium, characterized by being formed by a spin coating method in an environment of s or more.
Furthermore, the following (8) to (12) are provided.
(8) The information recording medium according to any one of (1) to (3), wherein a protective layer is formed between the optical information recording layer and the base layer.
(9) The underlayer has a multilayer structure, and the content of the antifoaming agent or leveling agent on the side in contact with the print receiving layer is 2.6% by mass or less. An information recording medium according to any one of the above.
(10) The information recording medium according to any one of (1) to (3), wherein the underlayer has a single-layer structure.
(11) The base layer is composed of an ultraviolet curable resin having an acrylate monomer as a main component and an acrylic antifoaming agent or leveling agent content of 2.6% by mass or less. The information recording medium according to any one of the above. Here, the ultraviolet curable resin means a material obtained by curing an ultraviolet curable ink (ultraviolet curable composition) by ultraviolet irradiation.
(12) a step of preparing a substrate, a step of forming an optical information recording layer directly or via another layer on one main surface of the substrate, and the opposite side of the optical information recording layer of the substrate or And a step of forming an underlayer containing 2.6% by mass or less of an antifoaming agent or a leveling agent on the optical information recording layer, and an average secondary particle as a main component on the underlayer by spin coating. A method for producing an information recording medium, comprising a step of forming a print receiving layer comprising a porous layer containing inorganic fine particles having a diameter of 500 nm or less and polyvinyl alcohol.

  According to the present invention, it is possible to provide an information recording medium having a very high color developability, a high gloss and drying property, hardly scratched, and a good handling property of a print receiving layer coating solution, and a method for producing the same. .

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In addition, this invention is not limited to the following embodiment, It can implement by changing variously within the range of the summary. Further, the drawings used are used for explaining the present embodiment, and do not represent actual sizes.

(Information recording medium: Embodiment 1)
FIG. 1 is a schematic diagram for explaining an example of an information recording medium to which the present embodiment is applied. The information recording medium I shown in FIG. 1 is a substrate surface incident type, and includes a substrate 10 and an optical information recording layer 11 that records data as a layer sequentially stacked on one main surface of the substrate 10, Adhesion between the light reflecting layer 12 for reflecting the laser light L incident from the substrate 10 side, the protective layer 13 for protecting the light reflecting layer 12 and the optical information recording layer 11, and the print receiving layer 15 is improved. It has a structure having a base layer 14 for improving the color developability and gloss and a print receiving layer 15 as the outermost layer.
As shown in FIG. 1, the information recording medium I has a configuration called a substrate surface incident type, and the laser light L irradiated to the optical information recording layer 11 at the time of recording and reproduction is a substrate on the surface opposite to the print receiving layer 15. Incident from 10 directions. On the print receiving layer 15, characters and images are recorded by an ink jet printer having an ink jet recording head.
Here, although details will be described later, the defoaming agent or leveling agent contained in the underlayer 14 is 2.6% by mass or less, and the print receiving layer 15 has an average secondary particle diameter of 500 nm or less as a main component. It is composed of a porous layer containing certain inorganic fine particles and polyvinyl alcohol.

(Information recording medium: Embodiment 2)
FIG. 2 is a schematic diagram for explaining another embodiment of the information recording medium. The same components as those of the information recording medium I shown in FIG. The information recording medium II shown in FIG. 2 is a film surface incident type, and includes a substrate 10, a light reflection layer 12 stacked on the substrate 10, an optical information recording layer 11, and a protective layer 13. . Further, on the substrate 10 on the opposite side of the substrate 10 with respect to the substrate 10, an undercoat layer 14 for improving adhesion to the print receiving layer 15 and improving image coloring and gloss, and an outermost layer The print receiving layer 15 has a laminated structure. The substrate surface incidence type information recording medium shown in FIG. 1 is such that the laser light L applied to the optical information recording layer 11 during recording and reproduction is incident from the side of the protective layer 13 opposite to the print receiving layer 15. The same as in the case of I.
Again, although details will be described later, the defoaming agent or leveling agent contained in the underlayer 14 is 2.6% by mass or less, and the print receiving layer 15 has an average secondary particle diameter of 500 nm or less as a main component. It is composed of a porous layer containing certain inorganic fine particles and polyvinyl alcohol.

(Print receiving layer 15)
Hereinafter, the print receiving layer 15 will be described.
The print receiving layer 15 in the present embodiment contains inorganic fine particles having an average secondary particle diameter of 500 nm or less as main components and polyvinyl alcohol, and is configured as a porous layer.
By combining the print receiving layer 15 having such a structure with a predetermined underlayer 14 to be described later, the print receiving layer having high adhesion and low surface defects while maintaining high gloss and dryness. Layer 15 can be realized.
Here, the print receiving layer 15 which is a porous layer refers to the print receiving layer 15 which contains inorganic fine particles as a main component in the layer and absorbs ink mainly through pores formed in the coating film. . In addition, a main component is a component which has a ratio of 50 solid mass% or more with respect to the total solid of the component which comprises the printing receiving layer 15, Preferably, 60 solid mass%-90 solid mass% It has the ratio of the range of.

  Examples of the inorganic fine particles contained as the main component in the print receiving layer 15 include various known fine particles such as amorphous synthetic silica, alumina (aluminum oxide), alumina hydrate, calcium carbonate, magnesium carbonate, and titanium dioxide. . Among these, amorphous synthetic silica, alumina (aluminum oxide), and alumina hydrate are preferable in terms of ink absorbability and productivity. Furthermore, amorphous synthetic silica is preferred because the surface strength of the coating film is relatively high and it is easy to maintain the temporal stability of the coating solution.

  Amorphous synthetic silica can be broadly classified into wet method silica, gas phase method silica and others depending on the production method, and wet method silica and gas phase method silica are particularly preferable. In this embodiment, in particular, in order to satisfy both the stability over time of the coating liquid and the color developability when printed with a label printer having a relatively low color developability, average secondary particles Wet method silica (A) pulverized to a diameter of 500 nm or less, and gas phase method silica (B) having an average primary particle size of 10 to 20 nm, (A / B) = (70/30) to (30 / 70) is more preferable.

  Wet method silica is further classified into precipitation method silica, gel method silica, and sol method silica depending on the production method. Precipitated silica is produced by reacting sodium silicate and sulfuric acid under alkaline conditions. The silica particles that have grown are agglomerated and settled, and then processed through filtration, washing with water, drying, pulverization and classification. Examples of the precipitated silica are commercially available from Tosoh Silica Co., Ltd. (product name: Nip Seal), Tokuyama Co., Ltd. (product name: Toku Seal), and the like. Gel silica is produced by reacting sodium silicate and sulfuric acid under acidic conditions. During the ripening, the fine particles dissolve and reprecipitate so as to bind other primary particles, so that the distinct primary particles disappear and form relatively hard aggregated particles having an internal void structure. For example, it is commercially available from Tosoh Silica Co., Ltd. (product name: nip gel), Grace Japan Co., Ltd. (product name: syloid, silo jet) and the like. The sol method silica is also called colloidal silica and is obtained by heating and aging a silica sol obtained through metathesis of sodium silicate acid or the like through an ion exchange resin layer. For example, Nissan Chemical Industries, Ltd. (product name: Snowtex) Etc. are commercially available.

In the present embodiment, the wet process silica is used after being pulverized to an average secondary particle diameter of 500 nm or less. The average primary particle diameter of the wet process silica is preferably 50 nm or less, more preferably 3 nm to 40 nm, and the average aggregate particle diameter is preferably 5 μm to 50 μm. The wet-process silica having such an average primary particle size is preferably used after being finely pulverized to an average secondary particle size of 500 nm or less, more preferably about 20 nm to 200 nm in the presence of a cationic compound. When the average secondary particle size is excessively large, color developability and glossiness decrease.
Note that the average primary particle diameter is a diameter of a circle equal to the projected area of each of 100 arbitrary primary particles present in the obtained image obtained by observing fine particles of wet-process silica with an electron microscope, These average particle diameters are obtained.
In addition, the average secondary particle size means that the print receiving layer of the obtained recording material is observed with an electron microscope, and as in the case of average primary particles, any 100 aggregated particles present in the obtained image The average value of the particle diameters was determined.

  Since the wet process silica produced by a normal method has an average aggregate particle diameter of 1 μm or more, it is used after being finely pulverized. As a pulverization method, a wet dispersion method of mechanically pulverizing silica dispersed in an aqueous medium can be preferably used. At this time, it is preferable to use precipitated silica having an oil absorption of 210 ml / 100 g or less and an average aggregate particle diameter of 5 μm or more. By using such precipitated silica, an increase in the initial viscosity of the dispersion can be suppressed, high concentration dispersion can be achieved, and pulverization / dispersion efficiency can be increased, so that the fine particles can be pulverized. In addition, the productivity of recording paper is improved by using a high-concentration dispersion. The oil absorption is measured based on the description of JIS K-5101.

In the present embodiment, as a specific method for obtaining wet process silica having an average secondary particle diameter of 500 nm or less, it is preferable to first prepare a preliminary dispersion in which silica particles and a cationic compound are mixed. The preliminary dispersion liquid mixes and disperses the silica particles and the cationic compound using at least one dispersion apparatus such as a sawtooth blade type dispersion machine, a propeller blade type dispersion machine, or a rotor stator type dispersion machine. If necessary, an appropriate low boiling point solvent may be added. The solid content concentration of the silica preliminary dispersion is not particularly limited, but is preferably 15 solid mass% to 40 solid mass%, more preferably 20 solid mass% to 35 solid mass%. When the solid content concentration of the silica preliminary dispersion is excessively high, the dispersion tends to be impossible.
Next, by applying a stronger mechanical means, a dispersion of wet process silica having an average secondary particle size of 500 nm or less is obtained. As the mechanical means, a known method can be adopted, for example, a media mill such as a ball mill, a bead mill, a sand grinder, a high pressure homogenizer, a pressure disperser such as an ultra high pressure homogenizer, an ultrasonic disperser, a thin film swirl disperser, etc. Can be used.

As the cationic compound for dispersing the wet process silica, a cationic polymer is preferably used. Examples of the cationic polymer include polyethyleneimine, polydiallylamine, polyallylamine, and alkylamine polymer. Further, for example, JP-A-59-020696, JP-A-59-033176, JP-A-59-033177, JP-A-59-155088, JP-A-60-011389, JP 60-049990, JP 60-038882, JP 60-109894, JP 62-198493, JP 63-049478, JP 63-115780. As described in Japanese Patent Application Laid-Open No. 63-280681, Japanese Patent Application Laid-Open No. 01-040371, Japanese Patent Application Laid-Open No. 06-234268, Japanese Patent Application Laid-Open No. 07-125411, Japanese Patent Application Laid-Open No. 10-193976, and the like. A polymer having a primary amino group to a tertiary amino group or a quaternary ammonium base is preferably used.
In particular, in the present embodiment, diallylamine derivatives are preferably used as the cationic polymer from the viewpoint of the temporal stability of the coating solution. In view of dispersibility, dispersion viscosity, and stability over time, the molecular weight of these cationic polymers is preferably about 2,000 to 100,000, and more preferably about 2,000 to 30,000. The addition amount of the cationic polymer is preferably in the range of 1% by mass to 10% by mass with respect to silica.

  In the present embodiment, the vapor phase method silica is also called dry method silica with respect to the wet method silica, and is generally made by a flame hydrolysis method. Specifically, a method of making silicon tetrachloride by burning with hydrogen and oxygen is generally known. Also, silanes such as methyltrichlorosilane and trichlorosilane can be used instead of silicon tetrachloride. These silanes such as methyltrichlorosilane and trichlorosilane can be used either alone or mixed with silicon tetrachloride. Vapor phase method silica is commercially available from Nippon Aerosil Co., Ltd. (product name: Aerosil), Tokuyama Co., Ltd. (product name: QS type), and the like.

In the present embodiment, the average primary particle diameter of the vapor phase method silica is usually preferably about 10 nm to 20 nm. If the average primary particle diameter is in this range, the stability of the solution over time is good and high color developability is obtained. In order to obtain higher color developability, it is preferable to use those having an average primary particle diameter of 10 nm to 15 nm and a specific surface area of 150 m ² / g or more by the BET method.
Here, the BET method is a method for measuring the surface area of a powder by a vapor phase adsorption method, and is a method for obtaining a total surface area, that is, a specific surface area of a 1 g sample from an adsorption isotherm. Usually, nitrogen gas is often used as the adsorbed gas, and the method of measuring the amount of adsorption from the change in pressure or volume of the gas to be adsorbed is most often used. The most prominent expression for expressing the isotherm of multimolecular adsorption is the Brunauer, Emmett, and Teller equation, called the BET equation, which is widely used for determining the surface area. The adsorption amount is obtained based on the BET equation, and the surface area is obtained by multiplying the area occupied by one adsorbed molecule on the surface.

  In the present embodiment, as the vapor phase method silica, those having an average secondary particle diameter of 500 nm or less, preferably 10 nm to 300 nm, more preferably 20 nm to 200 nm can be used. Further, gas phase method silica dispersed in the presence of a cationic compound is preferably used. As a dispersion method, pre-mixing of the gas phase method silica and the dispersion medium by ordinary propeller stirring, turbine type stirring, homomixer type stirring, etc., then, a media mill such as a ball mill, a bead mill, a sand grinder, a high pressure homogenizer, It is preferable to perform dispersion using a pressure disperser such as a high-pressure homogenizer, an ultrasonic disperser, a thin film swirl disperser, or the like.

  As the cationic compound preferably used for the dispersion of the vapor phase silica, the same cationic compound as that used for the dispersion of the wet method silica can be used. Similarly, a diallylamine derivative is preferably used as the cationic polymer from the viewpoint of the temporal stability of the coating solution. In view of dispersibility, dispersion viscosity, and stability over time, the molecular weight of these cationic polymers is preferably about 2,000 to 100,000, and more preferably about 2,000 to 30,000. The addition amount of the cationic polymer is preferably in the range of 1% by mass to 10% by mass with respect to silica.

In the present embodiment, the print receiving layer 15 contains polyvinyl alcohol as an essential component. By using polyvinyl alcohol, the transparency of the print receiving layer 15 is improved and the color developability is improved. Polyvinyl alcohol has low swellability at relatively near room temperature and high binding ability with inorganic fine particles, so that ink absorbability is good, and good adhesion to the substrate 10 is obtained.
Although there is no restriction | limiting in particular as polyvinyl alcohol, Preferably, saponified polyvinyl alcohol or cation modified polyvinyl alcohol can be used. Here, partially saponified polyvinyl alcohol can also be used.
The content of polyvinyl alcohol in the print receiving layer 15 is preferably 5% by mass to 50% by mass and more preferably 10% by mass to 30% by mass with respect to the inorganic fine particles from the viewpoint of ink absorbability. It is solid content mass%.

The cation-modified polyvinyl alcohol is, for example, a primary amino group to a tertiary amino group or a quaternary ammonium group as described in JP-A No. 61-014083, and the main chain or side chain of polyvinyl alcohol. Examples thereof include polyvinyl alcohol.
The saponification degree of polyvinyl alcohol is preferably 80% or more partially saponified or completely saponified. The average degree of polymerization of polyvinyl alcohol is preferably 500 to 5,000. In particular, the average degree of polymerization is preferably 3,000 to 4,000 from the viewpoint of the coating property of the print receiving layer 15 and the ink absorbability.

  In the present embodiment, the print receiving layer 15 can contain a hardening agent together with polyvinyl alcohol. Examples of the hardener include boron compounds. Examples of such boron compounds include boric acid, borates, borax and the like. A boron compound can be used 1 type or in combination of 2 or more types. Among these, examples of the borate include orthoborate, metaborate, diborate, tetraborate, and pentaborate.

  In the present embodiment, it is preferable that the print receiving layer 15 contains a cationic fixing agent in order to improve color developability and water resistance. As the cationic fixing agent, various cationic polymers and various polyvalent metals exemplified as the cationic compound used for the dispersion of the wet process silica described above can be used. Among these, it is preferable to use water-soluble polyvalent metals represented by water-soluble aluminum compounds and water-soluble zirconium compounds. These compounds may be any of inorganic salts, single salts or double salts of organic acids, metal complexes, and the like.

The water-soluble aluminum compound used in the present embodiment includes, for example, aluminum chloride or a hydrate thereof, aluminum sulfate or a hydrate thereof, an inorganic salt such as ammonium alum; an inorganic system such as a basic polyaluminum hydroxide compound Examples thereof include aluminum-containing cationic polymers.
Among these water-soluble aluminum compounds, a basic polyaluminum hydroxide compound is preferable because it can be stably added to a coating solution for forming the print receiving layer 15.

The basic polyaluminum hydroxide compound is a water-soluble compound that contains a basic, high molecular weight polynuclear condensed ion stably as shown in the following (formula 1), (formula 2), and (formula 3). Polyaluminum hydroxide.
[Al ₂ (OH) _n Cl _6-n ] _m (Formula 1)
[Al (OH) ₃ ] _n AlCl ₃ (Formula 2)
Al _n (OH) _m Cl _(3n-m) (0 <m <3n) (Formula 3)
Examples of such polynuclear condensed ions include [Al ₆ (OH) ₁₅ ] ³⁺ , [Al ₈ (OH) ₂₀ ] ⁴⁺ , [Al ₁₃ (OH) ₃₄ ] ⁵⁺ , and [Al ₂₁ (OH) ₆₀ ] ^3+. Etc.

  Such basic polyaluminum hydroxide compounds include Taki Chemical Co., Ltd. (water treatment agent: polyaluminum chloride PAC), Asada Chemical Co., Ltd. (polyaluminum hydroxide Paho), and Riken Green Co., Ltd. (product name: Purachem WT). ), Etc., and other manufacturers are also commercially available for the same purpose, and products of various grades can be easily obtained. In this embodiment, these commercially available products can be used as they are.

  Examples of the water-soluble zirconium compound used in the present embodiment include zirconium acetate, zirconium nitrate, basic zirconium carbonate, zirconium hydroxide, zirconium carbonate / ammonium, zirconium carbonate / potassium, zirconium sulfate, zirconium fluoride, zirconium chloride, Zirconium chloride octahydrate, zirconium oxychloride, hydroxy zirconium chloride and the like can be mentioned.

Among these, a zirconium acetate (zirconyl) compound is particularly preferable, and can be stably added to the coating solution for forming the print receiving layer 15, and excellent bleeding resistance can be obtained.
These water-soluble zirconium compounds are commercially available from, for example, Daiichi Rare Element Chemical Co., Ltd. (product names: Zircosol ZA-20, ZA-30, etc.), Nippon Light Metal Co., Ltd. and the like.
The total addition amount of the water-soluble aluminum compound and the water-soluble zirconium compound in the print receiving layer 15 is preferably 10 solid mass% or less, more preferably 0.5 solid mass% to 8 solid mass% relative to the inorganic fine particles. preferable.

The print receiving layer 15 in the present embodiment comprises at least one selected from a polymer latex containing a polymer having an average particle diameter of 100 nm or less and a glass transition temperature Tg of 40 ° C. or less and an alkanediol having 3 to 5 carbon atoms. It is preferable to contain.
When the print receiving layer 15 contains at least one selected from such polymer latex and alkanediol, drying of the print receiving layer 15 is maintained while maintaining the color developability, gloss and drying properties of the print receiving layer 15. The shrinkage variation of the coating layer due to the shrinkage rate and temperature / humidity variation can be suppressed. Furthermore, the coating solution of the print receiving layer 15 has high temporal stability and good handling properties.

  In the present embodiment, the polymer latex is a polymer latex polymerized by an emulsion polymerization method, for example, a styrene-butadiene copolymer latex, a polyacrylate ester latex, a polymethacrylate ester latex, a vinyl acetate latex. Ethylene-vinyl acetate latex is preferably used.

  The average particle size of the polymer latex is preferably 100 nm or less. Moreover, it is preferable that the glass transition temperature Tg of the polymer contained in polymer latex is 40 degrees C or less. When the average particle diameter of the polymer latex is excessively large, the transparency of the print receiving layer 15 is lowered, and the color developability tends to be deteriorated or the gloss tends to be lowered. If the glass transition temperature Tg of the polymer contained in the polymer latex is excessively high, the plasticizing effect obtained by adding the polymer latex to the print receiving layer 15 is reduced, and the drying shrinkage rate, temperature and humidity of the print receiving layer 15 are reduced. There is a tendency that the shrinkage fluctuation of the coating layer due to the change is difficult to suppress, and the effect of improving the stability over time of the coating solution is difficult to obtain.

  The amount of the polymer latex used is preferably 5% by mass to 30% by mass and more preferably 5% by mass to 20% by mass with respect to the inorganic fine particles contained in the print receiving layer 15. When the amount of the polymer latex used is excessively small, the effect of suppressing fluctuations in shrinkage of the coating layer tends to be insufficient. Further, when the amount of the polymer latex used is excessively large, the ink absorbability tends to decrease.

  Examples of the alkanediol having 3 to 5 carbon atoms include propanediol, butanediol, pentanediol and isomers thereof; branched butanediol such as 3-methyl-1,3-butanediol. Among these, propanediol and butanediol having 3 to 4 carbon atoms are preferable, and propanediol is particularly preferable. Examples of propanediol include propylene glycol (1,2-propanediol) and trimethylene glycol (1,3-propanediol), and propylene glycol is particularly preferable. The amount of the alkanediol having 3 to 5 carbon atoms in the print receiving layer 15 is preferably 0.1% by mass to 50% by mass with respect to the inorganic fine particles, and preferably 1% by mass to 20% by mass. More preferred is mass%.

The film thickness of the print receiving layer 15 in the present embodiment is preferably 10 μm or more, more preferably 15 μm or more. Moreover, 200 micrometers or less are preferable, More preferably, it is 100 micrometers or less, Most preferably, it is 50 micrometers or less.
When the film thickness of the print receiving layer 15 is excessively thin, the ink-jet ink absorption amount becomes insufficient, and the color developability tends to decrease. Further, when the thickness of the print receiving layer 15 is excessively large, the manufacturing cost tends to increase.

  In the present embodiment, the information recording media I and II may further include an overcoat layer on the print receiving layer 15. By providing the overcoat layer, the surface strength can be further improved and the storability of the image can be improved. The overcoat layer needs to have a property of receiving ink or allowing ink to permeate quickly. The layer thickness of the overcoat layer is preferably 0.01 μm to 1000 μm, more preferably 0.1 μm to 100 μm.

  In the present embodiment, the application method of the print receiving layer 15 is not particularly limited, and a known application method can be used. Known coating methods include, for example, a slide lip method, a curtain method, an extrusion method, an air knife method, a roll coating method, a rod bar coating method, a screen printing method, a spray coating, a spin coating, and a dip coating method. Among these, it is preferable to form the print receiving layer 15 by a spin coating method.

  When the print receiving layer 15 is formed by spin coating, the viscosity of the coating solution is preferably 200 mPa · s or more and 1200 mPa · s or less. Further, the number of rotations at the time of spin coating is preferably 500 rpm or more and 2000 rpm or less. If an attempt is made to form the print-receiving layer 15 having a desired film thickness under conditions other than the viscosity and the number of rotations at the time of shaking, coating unevenness occurs and the coating liquid does not spread to the outermost periphery of the substrate 10. Such a problem may occur and the film thickness may become non-uniform.

Further, when the print receiving layer 15 is formed by the spin coating method, it is performed in an environment where the exhaust air velocity from the center of the information recording mediums I and II to the outer peripheral direction of the information recording media I and II is 4 m / s or more. It is preferable. Here, the outer peripheral portion refers to a place of about 1 mm to 10 mm directly above the outer peripheral edge of the information recording media I and II. The exhaust wind speed can be measured with a commercially available anemometer. A method for controlling the exhaust wind speed can be selected as appropriate. For example, a spin coater described in Japanese Patent Application Laid-Open No. 2007-237103 is applicable.
By forming the print receiving layer 15 in the above-described environment, it is possible to suppress defects due to coating liquid splashes that occur when the print receiving layer 15 is formed. , II.
Further, when the print receiving layer 15 is formed by the spin coating method, it is performed in an environment where the exhaust air velocity from the center of the information recording mediums I and II to the outer peripheral direction of the information recording media I and II is 10 m / s or less. It is preferable. When performed in an environment where the exhaust air speed is 10 m / s or less, it prevents the disc from being damaged by the exhaust air and coming off the transport hand when the disc is carried into or out of the spin coater. I can do things.

In the present embodiment, if an overcoat layer is provided on the print receiving layer 15 in the present embodiment, the overcoat layer can contain known inorganic fine particles, swellable resin, organic resin fine particles and the like. Of these, inorganic fine particles and organic resin fine particles are mainly preferred from the viewpoint of ink acceptability and ink permeability.
When providing an overcoat layer, the coating amount of the coating solution coated on the print-receiving layer ^15, preferably from ^{0.01g / m 2 ~10g / m 2} , 0.1g / m 2 ~5g / m 2 is Further preferred.

  In the present embodiment, when the print receiving layer 15 is formed, the drying temperature of the coating solution applied onto the underlayer 14 is preferably 10 ° C. to 60 ° C., more preferably 15 ° C. to 30 ° C. . When the drying temperature is excessively low, the drying time tends to be long and the production efficiency tends to decrease. When the drying temperature is excessively high, the quality of the optical information recording layer 11 having low heat resistance deteriorates, and errors tend to occur frequently when information is recorded or reproduced.

(Underlayer 14)
Next, the underlayer 14 will be described.
In the present embodiment, the base layer 14 is provided under the print receiving layer 15. By providing the base layer 14, in the case of the substrate surface incidence type information recording medium I shown in FIG. 1, the adhesion between the print receiving layer 15 and the protective layer 13 is increased, and the gloss of the print receiving layer 15 is improved. . In the case of the film surface incidence type information recording medium II shown in FIG. 2, the adhesion between the print receiving layer 15 and the substrate 10 is increased, and the gloss of the print receiving layer 15 is improved.

The surface roughness Ra of the underlayer 14 is preferably 1.0 μm or less, and more preferably 0.3 μm or less. By providing such a base layer 14, the print receiving layer 15 can obtain high color development and gloss like photographic printing paper.
The surface roughness Ra of the underlayer 14 can be generally reduced by reducing the viscosity of the ink and increasing the leveling time until the underlayer 14 is dried or cured after being formed.

  Here, the surface roughness Ra is a center plane average roughness defined in JIS-B0601: 2001. The surface roughness Ra is a measurement value measured using a stylus type surface roughness meter, and the reference length is 8 mm. When measuring the surface roughness Ra, the reference length is extracted from a portion having no extremely high convex portion or deep concave portion that is regarded as a scratch. In addition, when the surface shape has directionality, the measurement is performed in the direction in which the surface roughness Ra appears most.

  The formation method of the underlayer 14 is not particularly limited, and a conventionally known method can be used. Usually, from the viewpoint of productivity, it is preferable to form the underlayer 14 by screen printing or offset printing using a known radiation curable resin. The radiation curable resin is a resin that is cured by electromagnetic waves such as ultraviolet rays, electron beams, X-rays, γ rays, and infrared rays. As the radiation, ultraviolet rays and electron beams are preferable. When the underlayer 14 is formed by screen printing using a radiation curable resin, time for leveling the resin after printing is necessary as appropriate from the viewpoint of smoothness of the information recording medium.

Examples of the composition component of the radiation curable resin used when forming the base layer 14 include a resin in which an acrylate monomer and an acrylic oligomer are mixed, and a polymerization initiator.
Here, as an acryl-type monomer, an ester acrylate monomer, an epoxy acrylate monomer, etc. are mentioned, for example. Examples of acrylic oligomers include ethylene glycol acrylate oligomers and urethane acrylate oligomers. Examples of the polymerization initiator include acetophenone-based polymerization initiators such as 1-hydroxycyclohexyl phenyl ketone, 2-hydroxy-2-methyl-1-phenylpropan-1-one, and 2,2-diethoxyacetophenone; Examples include thioxanthone-based polymerization initiators such as 4-diethylthioxanthone. In addition, as a composition component of the radiation curable resin, a colorant such as titanium oxide can be further added.

In the present embodiment, the underlayer 14 contains an antifoaming agent or a leveling agent. The content of the antifoaming agent or leveling agent in the underlayer 14 is 2.6% by mass or less, preferably 1.6% by mass or less, more preferably 1.0% by mass with respect to the total solid mass of the underlayer 14. It is below mass%. However, the content of the antifoaming agent or leveling agent is usually 0.1% by mass or more, preferably 0.5% by mass or more.
When the content of the antifoaming agent or leveling agent contained in the underlayer 14 is excessively large, the adhesion between the print receiving layer 15 and the underlayer 14 is lowered, or it is applied to form the print receiving layer 15. There is a tendency that the coating solution is bounced and cannot be applied uniformly. If the content of the antifoaming agent or leveling agent is excessively small, the gloss of the print receiving layer 15 tends to deteriorate due to the surface roughness of the underlayer 14.

In the present embodiment, what is used as an antifoaming agent or a leveling agent is generally a substance having a small surface tension. Further, when the interfacial tension of the main component of the ink added to the underlayer 14 is large, these substances are likely to become a dispersion in the ink and easily exhibit an antifoaming effect. In addition, when the interfacial tension of the main agent of the ink added to the underlayer 14 is small, these substances are easily diffused into the ink and easily exert a leveling effect.
As described above, since the same substance functions as an antifoaming agent and a leveling agent, in this embodiment, one substance is referred to as an “antifoaming agent or leveling agent”. In any case, since the surface tension is small, bleed-out on the surface of the underlayer 14 has a great influence on the coating properties of the coating liquid applied on the underlayer 14.

Examples of the type of antifoaming agent or leveling agent used in the present embodiment include silicon-based, modified silicon-based, fluorine-based, and non-silicon-based materials.
Among these, a silicon-based, modified silicon-based, fluorine-based antifoaming agent or leveling agent is effective by adding a relatively small amount to the underlayer 14, and the amount added is smaller than that in the case of non-silicon-based. It is preferable.
Examples of the non-silicon type include acrylic type and vinyl type. In addition to these, specifically, 2-ethylhexanol, diisobutyl carbinol, oleic acid, tall oil, sorbitan lauric acid monoester, sorbitan oleic acid monoester, sorbitan oleic acid triester, low molecular weight polyethylene glycol olein Organic esters such as acid esters, nonylphenol EO low molar adducts, pluronic EO low molar adducts, polypropylene glycol, polypropylene glycol derivatives, copolymers of acrylic acid and budadiene, (meth) acrylic acid ester polymers, mineral oils And antifoaming agents.
Of these, (meth) acrylic acid ester polymers are preferable, and (meth) acrylic acid ester copolymers are particularly preferable. The ester portion of (meth) acrylic acid ester is a straight chain having 1 to 10 carbon atoms such as methyl, ethyl, propyl, butyl (t-, i-, etc.), pentyl, hexyl, heptyl, octyl, 2-ethylhexyl, etc. Or what is chosen from the branched alkyl group is mentioned. The (meth) acrylic acid ester copolymer is preferably a copolymer of a linear alkyl ester having 1 to 4 carbon atoms of acrylic acid and a branched alkyl ester having 4 to 10 carbon atoms of acrylic acid. Among these, a copolymer of ethyl (meth) acrylate and 2-ethylhexyl (meth) acrylate is preferable. A copolymer of ethyl acrylate / ethyl methacrylate / 2-ethylhexyl acrylate / 2-ethylhexyl methacrylate is particularly preferred.
The weight average molecular weight is usually 1000 or less, preferably 800 or less, and usually 150 or more.

The film thickness of the underlayer 14 is preferably 0.1 μm to 100 μm, more preferably 1 μm to 50 μm, and most preferably 3 μm to 20 μm.
The underlayer 14 may be formed of a single layer or a multilayer structure formed of a plurality of layers. By providing the base layer 14 with a multilayer structure, a layer having high adhesion to the print receiving layer 15 and good wettability is disposed at the interface with the print receiving layer 15, while the protective layer 13 or the substrate 10 and It is possible to add gloss to the interface or to arrange a colored layer as a background color.

In this manner, by assigning various functions to each layer, the degree of freedom in development of the underlayer 14 is increased, and a layer with better performance can be provided. That is, when the underlayer 14 has a multilayer structure, the content of the antifoaming agent or leveling agent contained in the underlayer 14 closest to the print receiving layer 15 may be in the above range. For 14, the leveling agent or antifoaming agent content may exceed 2.6% by mass.
On the other hand, when the underlayer 14 is provided as a single layer, the underlayer 14 can be provided by a single printing operation, which is simple and inexpensive. In addition, the influence on the mechanical characteristics of the disk is small compared to the case of the multilayer structure.

(Substrate 10)
In the present embodiment, the material of the substrate 10 can be plastic, metal, glass or the like having appropriate processability and rigidity. In the case of the substrate surface incident type information recording medium I shown in FIG. 1, normally, transparency is required for the laser beam L for recording / reproducing. On the other hand, in the case of the film surface incidence type information recording medium II shown in FIG. 2, there are no restrictions on the transparency and birefringence of the recording / reproducing laser beam L.
The thickness of the substrate 10 is not particularly limited, but is usually preferably in the range of 0.5 mm or more and 1.3 mm or less.

  The substrate 10 is usually formed with a guide groove for tracking. The tracking guide groove is usually provided on the substrate 10 as a concentric or spiral groove. The track pitch of the guide groove varies depending on the wavelength of the laser beam L used for recording / reproducing of the information recording media I and II. Specifically, in CD (Compact Disk) type information recording media I and II, the track pitch is usually 1.4 μm or more and 1.7 μm or less. In DVD (Digital Versatile Disk) information recording media I and II, the track pitch is usually 0.7 μm or more and 0.8 μm or less. In the information recording media I and II for blue laser, the track pitch is usually 0.1 μm or more and 0.6 μm or less.

  On the other hand, the groove depth of the guide groove also differs depending on the wavelength of the laser beam L used for recording / reproducing of the information recording media I and II. Specifically, in the CD information recording media I and II, the groove depth is usually 10 nm or more and 300 nm or less. In the DVD-type information recording media I and II, the groove depth is usually 10 nm or more and 200 nm or less. In the information recording media I and II for blue laser, the groove depth is usually 10 nm or more and 200 nm or less.

  Moreover, when forming a guide groove in the surface of the board | substrate 10, it is as follows. Specifically, when metal or glass is used as the material of the substrate 10, usually a thin resin layer of a photocurable resin or a thermosetting resin is provided on the surface of these materials, and grooves are formed in the resin layer. . When plastic is used as the material for the substrate 10, the shape of the substrate 10 and the guide grooves on the surface are formed all at once by injection molding. Examples of plastic materials that can be used for injection molding include polycarbonate resins, polyolefin resins, acrylic resins, and epoxy resins that are conventionally used in CDs and DVDs.

  As the substrate 10, a ring-shaped substrate having a center hole at the center is generally used. The ring shape is not particularly limited, and various shapes such as a disk shape, an ellipse shape, and a polygon shape can be considered. However, the substrate 10 is usually disk-shaped. In this case, the diameter of the substrate 10 is usually about 80 mm or 120 mm.

(Optical information recording layer 11)
Next, the optical information recording layer 11 will be described.
The optical information recording layer 11 is made of a material capable of recording digital information as a result of changes in optical characteristics, physical characteristics, and the like when irradiated with the laser beam L. The materials constituting the optical information recording layer 11 are generally roughly classified into organic dye materials used for write-once information recording media and inorganic substances used for rewritable information recording media.

  Examples of the organic dye material used for the write-once information recording medium include macrocyclic azaannulene dyes such as phthalocyanine dyes, naphthalocyanine dyes, porphyrin dyes; polymethine dyes such as cyanine dyes, merocyanine dyes, and squarylium dyes; And dyes, azulenium dyes, metal-containing azo dyes, metal-containing indoaniline dyes, and the like. In particular, metal-containing azo dyes are preferable because of their excellent durability.

  When the optical information recording layer 11 is formed using an organic dye material, usually, a solution obtained by dissolving the organic dye material in an appropriate solvent is used, and a coating method such as spin coating, spray coating, dip coating, or roll coating is employed. The In this case, the solvent is usually a ketone alcohol solvent such as diacetone alcohol or 3-hydroxy-3-methyl-2-butanone; a cellosolve solvent such as methyl cellosolve or ethyl cellosolve; a tetrofluoropropanol, octafluoropentanol or the like. Perfluoroalkyl alcohol solvents; hydroxyethyl solvents such as methyl lactate and methyl isobutyrate;

  The thickness of the optical information recording layer 11 is appropriately selected depending on the recording method and the like, and is not particularly limited, but is usually 1 nm or more, preferably 5 nm or more, particularly preferably 10 nm or more in order to obtain a sufficient degree of modulation. However, from the viewpoint of transmitting light, the thickness of the optical information recording layer 11 is usually 1 μm or less, preferably 0.5 μm or less, more preferably 100 nm or less.

Note that a thin film of an inorganic material can be used as the optical information recording layer 11 of the write-once information recording medium. As a thin film of such an inorganic material, for example, a chalcogen-based alloy film such as Ge · Te, Ge · Sb · Te; a two-layer film such as Si / Ge, Al / Sb; (partial) nitriding such as BiGeN and SnNbN Examples of the film include (partial) oxide films such as TeOx and BiFOx. These thin films are usually formed by sputtering.
In this case, the film thickness of the optical information recording layer 11 is usually 1 nm or more, preferably 2 nm or more, and usually 50 nm or less, preferably 20 nm or less.

  As the inorganic substance used for the rewritable information recording medium, a material capable of reversibly recording / erasing is employed. Examples of such materials include phase change materials such as SbTe, GeTe, GeSbTe, InSbTe, AgSbTe, AgInSbTe, GeSb, GeSbSn, InGeSbTe, and InGeSbSnTe. These are usually formed by sputtering.

(Light reflection layer 12)
In the present embodiment, the material constituting the light reflecting layer 12 preferably has a high reflectance with respect to the recording / reproducing light wavelength and a reflectance of 70% or more with respect to the recording / reproducing light wavelength.
Examples of visible light used as recording / reproducing light, particularly those exhibiting high reflectivity in the blue wavelength region, include Au, Ag, Al, and alloys containing these as main components. Among these, an alloy containing Ag as a main component is more preferable because of its high reflectance and low absorption.
Further, by adding other elements to the alloy containing Ag as a main component, the corrosion resistance of the light reflecting layer 12 to moisture, oxygen, sulfur, and the like can be improved. Examples of other elements added include Au, Cu, rare earth elements (particularly Nd), Nb, Ta, V, Mo, Mn, Mg, Cr, Bi, Al, Si, and Ge. The addition amount of other elements is usually 0.01 atomic% to 10 atomic%. Since Ag has the property of improving flatness by adding an additive, the amount of other elements added is preferably 0.1 atomic% or more, and more preferably 0.5 atomic% or more.
In addition, a dielectric mirror in which a plurality of dielectric layers are stacked can be used as the light reflecting layer 12.

The film thickness of the light reflection layer 12 is preferably 70 nm or less, more preferably 65 nm or less. Further, the lower limit of the film thickness of the light reflecting layer 12 is preferably 30 nm or more, more preferably 40 nm or more, except when a laminated information recording medium described later is formed.
The surface roughness Ra of the light reflecting layer 12 is preferably 5 nm or less, and more preferably 1 nm or less.
The light reflecting layer 12 can be formed by sputtering, ion plating, electron beam evaporation or the like.

(Protective layer 13)
The protective layer 13 has different required characteristics between the case of the substrate surface incidence type information recording medium I shown in FIG. 1 and the case of the film surface incidence type information recording medium II shown in FIG. The cases will be described separately.

(Protective layer 13 in case of substrate surface incidence type)
In the case of the substrate surface incident type information recording medium I shown in FIG. 1, the material constituting the protective layer 13 is not particularly limited as long as it protects the light reflecting layer 12 and the optical information recording layer 11 from external force. Examples of such materials include organic materials such as thermoplastic resins, thermosetting resins, electron beam curable resins, ultraviolet (hereinafter referred to as “UV”) curable resins; silicon oxide, silicon nitride, fluorine Examples thereof include inorganic materials such as magnesium halide (MgF ₂ ) and tin oxide (SnO ₂ ).

When a thermoplastic resin, a thermosetting resin, or the like is used as a material constituting the protective layer 13, a coating solution prepared by dissolving these materials in an appropriate solvent is applied onto the light reflecting layer 12 and dried. By doing so, the protective layer 13 is formed.
When a UV curable resin is used as the material constituting the protective layer 13, a coating solution prepared by dissolving the UV curable resin as it is or in an appropriate solvent is applied onto the light reflecting layer 12, and UV light is applied. The protective layer 13 is formed by curing by irradiation.
Examples of the UV curable resin include acrylate resins such as urethane acrylate, epoxy acrylate, and polyester acrylate. These materials may be used alone or in combination of two or more. Further, the protective layer 13 may be formed as a single layer or a multilayer.

  Examples of the method for forming the protective layer 13 include spin coating, casting, and other coating methods; sputtering, chemical vapor deposition, and the like. Of these, spin coating is preferred. The film thickness of the protective layer 13 is usually 0.1 μm or more, preferably 3 μm or more because a certain amount of thickness is required to fulfill its protective function. However, the film thickness of the protective layer 13 is usually 100 μm or less, preferably 30 μm or less. If the protective layer 13 is excessively thick, the effect obtained by providing the protective layer 13 is not changed, and it takes a long time to form the protective layer 13 and the cost tends to increase. .

(About the protective layer 13 in the case of the film surface incidence type)
In the case of the film surface incidence type information recording medium II shown in FIG. 2, the material constituting the protective layer 13 includes a light reflecting layer 12 and an intensity for protecting the optical information recording layer 11 from external force, and a recording / reproducing laser beam. The property of being transparent to L and having little birefringence is required.

As a method for forming the protective layer 13, usually, an adhesive method in which a plastic plate (hereinafter referred to as a sheet material) is bonded to the optical information recording layer 11 using an adhesive, a thermoplastic resin, a thermosetting resin, an electronic material, and the like. An application method in which a coating liquid prepared using a curable material such as a linear curable resin or a UV curable resin is applied on the optical information recording layer 11 and then the curable material is cured by light, radiation, heat, or the like. Can be mentioned.
The protective layer 13 preferably has a transmittance of 70% or more and more preferably 80% or more with respect to the wavelength λ of the laser beam L for recording and reproduction.

  Examples of the plastic used as the sheet material described above include polycarbonate, polyolefin, acrylic, cellulose triacetate, and polyethylene terephthalate. Examples of the adhesive include a photocurable resin, a radiation curable resin, a thermosetting resin, and a pressure sensitive adhesive. Among these, pressure-sensitive adhesives include pressure-sensitive adhesives made of various polymers such as acrylic, methacrylate, rubber, silicon, and urethane.

When the sheet material is bonded to the optical information recording layer 11 by an adhesive method using an adhesive, for example, a photocurable resin as an adhesive is dissolved in an appropriate solvent to prepare a coating solution. Is coated on the optical information recording layer 11 to form a coating film, and a sheet material is overlaid on the coating film. Thereafter, if necessary, the medium is rotated in a state where the sheet materials are overlapped, and the coating liquid is further stretched and developed, and then irradiated with ultraviolet rays with a UV lamp to cure the photocurable resin.
When using a pressure-sensitive adhesive, a sheet material previously coated with a pressure-sensitive adhesive is superimposed on the optical information recording layer 11, and then pressed and pressed with an appropriate pressure.

The pressure-sensitive adhesive exemplified as the pressure-sensitive adhesive is preferably an acrylic or methacrylate polymer pressure-sensitive adhesive from the viewpoint of transparency and durability. More specifically, the polymer adhesive is composed of a main component monomer (for example, 2-ethylhexyl acrylate, n-butyl acrylate, iso-octyl acrylate, etc.) and a polar monomer (for example, acrylic acid, methacrylic acid, acrylamide derivative, malein). Acid, hydroxylethyl acrylate, glycidyl acrylate, etc.).
The physical properties of the main component monomer include the molecular weight of the main component monomer and the physical properties such as the glass transition temperature Tg, tack performance (adhesive force immediately formed when contacted at a low pressure), peel strength, and shear holding strength of the polymer adhesive. It can be controlled by the ratio of short chain components and the density of crosslinking points by acrylic acid.
Examples of the solvent for dissolving the acrylic polymer include ethyl acetate, butyl acetate, toluene, methyl ethyl ketone, and cyclohexane. Furthermore, the polymer adhesive preferably contains a polyisocyanate-based crosslinking agent.

When the sheet material is bonded onto the optical information recording layer 11 using the above-mentioned adhesive, after a predetermined amount of the adhesive is uniformly applied to the surface of the sheet material in contact with the optical information recording layer 11 side and the solvent is dried Then, the optical information recording layer 11 side surface is cured by applying pressure with a laminating roller or the like. When adhering the sheet material coated with the pressure-sensitive adhesive on the optical information recording layer 11, it is preferably bonded in a vacuum in order to prevent air from being involved and forming bubbles.
Also, after applying the above-mentioned pressure-sensitive adhesive on the release film and drying the solvent, the sheet material is bonded to this, and the release film is peeled off to integrate the sheet material and the pressure-sensitive adhesive layer. It may be bonded onto the recording layer 11.

  Next, when the protective layer 13 is formed by a coating method, a spin coating method, a dip method or the like is used. In particular, when the protective layer 13 is formed on a disk-shaped medium, a spin coating method is preferable. As a material used when forming the protective layer 13 by a coating method, a urethane resin, an epoxy resin, an acrylic resin, etc. are mentioned similarly to the case of the adhesion method mentioned above. In the case of the coating method, a coating solution prepared using these resins is coated on the optical information recording layer 11, and then the coating layer is irradiated with ultraviolet rays, electron beams, radiations, etc., and cured by promoting radical polymerization or cationic polymerization. Then, the protective layer 13 is formed.

If necessary, a hard coat layer having a thickness of about 0.1 μm to 50 μm may be further provided on the incident light side surface of the protective layer 13. By providing the hard coat layer, the scratch resistance, fingerprint resistance and the like of the protective layer 13 are improved.
The thickness of the protective layer 13 is appropriately selected depending on the wavelength λ of the recording / reproducing laser beam L and the NA (numerical aperture) of the objective lens, but is usually preferably in the range of 0.01 mm to 0.3 mm. A range of 0.05 mm to 0.15 mm is more preferable. In this case, it is preferable that the entire thickness including the thickness of the adhesive layer, the hard coat layer, and the like is in an optically acceptable thickness range. For example, in a so-called Blu-ray disc, it is preferable to control to about 100 μm ± 3 μm or less.

(Other configurations)
Note that the information recording media I and II described in the present embodiment may have arbitrary layers in addition to the above-described layers as long as they do not depart from the spirit of the present invention. For example, an interfacial layer can be inserted between the above layers in order to prevent contact / diffusion between the layers and to adjust the phase difference and reflectivity.
The present invention can also be applied to a laminated information recording medium having two or more optical information recording layers. In that case, each layer other than the print receiving layer 15 and the base layer 14 can be realized by appropriately changing the material, the film thickness, and the like. In any case, any structure may be used as long as the print receiving layer 15 and the underlayer 14 are provided on the outermost surface of the information recording medium opposite to the incident side of the recording / reproducing laser beam L.
The “method for spin-coating the print receiving layer in an environment where the exhaust air velocity from the center of the information recording medium to the outer periphery in the outer periphery of the information recording medium is 4 m / s or more” described in the present embodiment is: “The substrate, and at least an optical information recording layer and a print receiving layer on the substrate, the print receiving layer containing porous fine particles containing inorganic fine particles having an average secondary particle diameter of 500 nm or less and polyvinyl alcohol. It can also be preferably used in the production of an “information recording medium characterized by being a quality layer”.

  Hereinafter, the present invention will be described more specifically based on examples. However, the present invention is not limited to these. In addition, in the description of an Example or a comparative example, "part" and "%" are a solid content mass part and solid content mass%.

Example 1
−Preparation of information recording medium before forming print receiving layer−
A substrate having a groove with a width of 0.45 μm and a depth of 155 nm and a thickness of 1.2 mm was produced by injection molding using a polycarbonate resin. On this substrate, an alcohol solution of a metal-containing azo dye was applied by spin coating and dried to form an optical information recording layer having a thickness of 70 nm.
Subsequently, silver was sputtered on the optical information recording layer to form a light reflecting layer having a thickness of 60 nm. Subsequently, an ultraviolet curable resin (trade name: SD3300, manufactured by Dainippon Ink & Chemicals, Inc.) is applied onto the light reflecting layer by a spin coating method, and the ultraviolet curable resin is cured by ultraviolet irradiation using a high-pressure mercury lamp. Thus, a protective layer having a thickness of 5 μm was formed.

Thereafter, as an undercoat layer, an ultraviolet curable ink (ultraviolet curable composition: Jujo Chemical Co., Ltd.) containing 2.6% by mass of a non-silicon acrylic defoaming agent or leveling agent in advance and containing an acrylate monomer as a main component. A product name: Leicure Ink VID F32 TH) manufactured by Co., Ltd. was printed on the protective layer by screen printing and cured by irradiating with ultraviolet rays using a high-pressure mercury lamp to form a white underlayer having a thickness of 10 μm. The surface roughness Ra of the underlayer was in the range of 0.08 μm to 0.12 μm including all the following examples and comparative examples.
In addition, the physical property of the antifoamer or the leveling agent contained in the ultraviolet curable ink (ultraviolet curable composition: trade name: Leicure Ink VID F32 TH manufactured by Jujo Chemical Co., Ltd.) is as follows.
Main component: Copolymer of 2-ethylhexyl acrylate / 2-ethylhexyl methacrylate / ethyl acrylate / ethyl methacrylate / weight average molecular weight of about 550 / Appearance: colorless liquid / specific gravity: 0.99-1. 03
Boiling point: 205 ° C
・ Insoluble in water, soluble in most organic solvents ・ Nearly irritating to skin

-Formation of print receiving layer-
In water, 4 parts of dimethyldiallylammonium chloride homopolymer (molecular weight 9,000) and wet process silica (precipitation silica, oil absorption 200 ml / 100 g, average primary particle diameter 16 nm, average aggregated particle diameter 9 μm) are added, A preliminary dispersion was prepared using a sawtooth blade type disperser (blade peripheral speed 30 m / sec). Next, the obtained preliminary dispersion was treated with a bead mill to prepare a silica dispersion 1 having a solid content of 30%.

Next, 4 parts of dimethyldiallylammonium chloride homopolymer (molecular weight 9,000) and 100 parts of vapor phase method silica (average primary particle diameter 12 nm, specific surface area 200 m ² / g) are added to water, and a sawtooth blade type is added. A preliminary dispersion was prepared using a disperser (blade peripheral speed 30 m / sec) and then treated with a high-pressure homogenizer to prepare a silica dispersion 2 having a solid concentration of 25%.

  Using the above silica dispersion 1 and silica dispersion 2, the following print receiving layer formulation 1 is mixed at room temperature to prepare a print receiving layer coating solution having a solid content concentration of 16%, and using this, an information recording medium is used. Was made.

<Print receiving layer formulation 1>
Silica dispersion 1 (as silica solid content) 40 parts Silica dispersion 2 (as silica solid content) 60 parts Polyvinyl alcohol 22 parts (however, saponification degree 88%, average polymerization degree 3,500)
Boric acid 3.5 parts Zirconyl acetate 3 parts (Daiichi Elemental Chemical Co., Ltd. ZA30)
Industrial alcohol 25 parts (silica having an average secondary particle size of 500 nm or less is 78% by mass with respect to the total solid content of the components constituting the print receiving layer)

  On the underlayer of the information recording medium formed up to the underlayer by the above-described operation, the above print-receiving layer coating solution was applied by spin coating. The viscosity of the print-receiving layer coating solution was 400 mPa · s. Further, the spin rotation was performed at 900 rpm for 3 seconds. At this time, exhaust was performed from the outer periphery in the coater cup, and the exhaust air velocity from the center of the information recording medium to the outer periphery in the outer periphery of the information recording medium was 3 m / s. Then, it was left at room temperature of 25 ° C. for 20 minutes to produce an information recording medium 1 having a print receiving layer.

The coating conditions of the printing receiving layer coating solution were controlled so that the thickness of the printing receiving layer formed on the underlayer was about 20 μm. The coating conditions for the print-receiving layer coating solution are the same for the following examples and comparative examples.
Also, in the above-described printing receiving layer formulation 1, a coating solution was prepared by separately blending 100 parts of the silica dispersion 1 and 100 parts of the silica dispersion 2, and the base layer was prepared by the same operation as above. It was applied on top and dried. When each surface was observed with an electron microscope after drying, the average secondary particle diameter of silica was 100 nm.

(Example 2)
−Preparation of information recording medium before forming print receiving layer−
The same information recording medium as that in Example 1 was used before forming the underlayer. Next, the amount of the antifoaming agent or leveling agent contained in the ultraviolet curable ink (ultraviolet curable composition: manufactured by Jujo Chemical Co., Ltd .: Leicure Ink VID F32 TH) used in Example 1 was 1.6 mass. The ultraviolet curable ink was printed on the protective layer by screen printing and cured by irradiating with ultraviolet rays using a high-pressure mercury lamp to form a white underlayer having a thickness of 10 μm.

-Formation of print receiving layer-
By the same operation as in Example 1, a print receiving layer was formed on the underlayer, and the information recording medium 2 of Example 2 was produced.

(Example 3)
−Preparation of information recording medium before forming print receiving layer−
The same information recording medium as that in Example 1 was used before forming the underlayer. Next, the ultraviolet curable ink used in Example 1 (ultraviolet curable composition: product of Jujo Chemical Co., Ltd., trade name: Leicure Ink VID F32 TH) was printed on the protective layer by screen printing, and ultraviolet rays were used using a high-pressure mercury lamp. Was irradiated to form a white underlayer having a thickness of 10 μm.

-Formation of print receiving layer-
In Example 2, the information recording medium 3 of Example 3 was produced by the same operation except that the exhaust air velocity at the outer peripheral portion of the information recording medium was set to 4 m / s.

Example 4
−Preparation of information recording medium before forming print receiving layer−
As the information recording medium before forming the print receiving layer, one formed by the same operation as in Example 3 was used.

-Formation of print receiving layer-
An information recording medium 4 of Example 4 was produced in the same manner as in Example 3 except that the following printing receiving layer formulation 2 was used.

<Print receiving layer composition 2>
Silica dispersion 1 (as silica solid content) 100 parts polyvinyl alcohol 20 parts (however, saponification degree 88%, average polymerization degree 3,500)
3 parts of boric acid 3 parts of zirconyl acetate (ZA30 manufactured by Daiichi Elemental Chemicals)
Industrial alcohol 25 parts (silica having an average secondary particle diameter of 500 nm or less is 79% by mass with respect to the total solid content of the components constituting the print receiving layer)

(Example 5)
In Example 2, an underlayer and a print receiving layer were formed by the same operation as in Example 2 except that the amount of the defoaming agent or leveling agent was 0.1% by mass as the underlayer. The information recording medium 5 was prepared.

(Comparative Example 1)
In Example 2, a base layer and a print receiving layer were formed in the same manner as in Example 2 except that the amount of the antifoaming agent or leveling agent was 3.0% by mass as the base layer. The information recording medium 6 was produced.

(Comparative Example 2)
In Example 2, a base layer and a print receiving layer were formed by the same operation as in Example 2 except that the amount of the defoaming agent or leveling agent was 4.0% by mass as the base layer. The information recording medium 7 was prepared.

(Comparative Example 3)
By the same operation as in Example 2, an information recording medium provided up to the base layer was formed. Further, an ultraviolet curable resin composition was applied onto the underlayer by spin coating to form a print receiving layer, and the information recording medium 8 of Comparative Example 3 was produced.
Here, the ultraviolet curable resin composition comprises 30 parts of synthetic silica having an average primary particle diameter of 10 nm and a pore volume of 3 ml / g, 35 parts of acryloylformoline, 20 parts of alkylated polyvinylpyrrolidone resin, 10 parts of hydroxyethyl acrylate, cation A resin (Mitsubishi Chemical Co., Ltd. Saftmer) 3 parts and a photopolymerization initiator 2 parts were blended and prepared.
The print receiving layer prepared here does not contain polyvinyl alcohol, is a so-called swelling type, and is not porous.

(Comparative Example 4)
In Comparative Example 3, the base layer and the print receiving layer were formed in the same manner as in Comparative Example 3 except that the amount of the antifoaming agent or leveling agent in the base layer was 2.6% by mass. The information recording medium 9 of Example 4 was produced.

(Comparative Example 5)
In Comparative Example 3, the base layer and the print receiving layer were formed in the same manner as in Comparative Example 3 except that the amount of the defoaming agent or leveling agent in the base layer was 4.0% by mass. The information recording medium 10 of Example 5 was produced.
Each of the obtained information recording media (1 to 10) was evaluated for the following items. The results are shown in Table 1.

<Color development A>
Compared with a silver salt photograph produced by printing a person and a landscape image on the surface of a printable label layer with a commercially available inkjet printer capable of optical disc label printing (PM-G800 manufactured by Epson Corporation). The color developability was visually evaluated based on the above criteria.
(Double-circle): It has color development higher than a silver salt photograph.
○: It has color developability similar to a silver salt photograph.
Δ: Color development is slightly inferior to silver salt photographs.
X: The color developability is clearly inferior to that of a silver salt photograph.

<Color development B>
A person and a landscape image were printed on the surface of the printable label layer with a commercially available label printer capable of optical disc label printing (480i manufactured by Reage Inc.), and evaluated according to the following criteria in the same manner as the above “color development A”.
(Double-circle): It has color development higher than a silver salt photograph.
○: It has color developability similar to a silver salt photograph.
Δ: Color development is slightly inferior to silver salt photographs.
X: The color developability is clearly inferior to that of a silver salt photograph.

<Glossiness>
Using a commercially available inkjet printer capable of optical disk label printing (PM-G800, manufactured by Epson Corporation), a person and a landscape image were printed on the surface of the print receiving layer, and compared with a silver salt photograph produced using the image, The glossiness was visually evaluated on the basis.
○: Glossiness equivalent to that of a silver salt photograph.
(Triangle | delta): Glossiness is inferior somewhat compared with a silver salt photograph.
X: The gloss is clearly inferior to that of a silver salt photograph.

<Drying>
Using a commercially available inkjet printer capable of optical disc label printing (PM-G800 manufactured by Epson Corporation), solid printing of red, blue, green, and black is performed on the print receiving layer surface, and PPC paper is superimposed on the printing section immediately after printing. The amount of ink that was lightly crimped and transferred to PPC paper was visually observed. Evaluation was made according to the following criteria.
○: Not transferred at all.
×: Partial transfer is difficult to use.

<Surface defects>
A state in which the print receiving layer was partially repelled by the underlying layer and defects were observed, and defects that were thought to be caused by the splash of the coating liquid during coating were observed and evaluated as follows.
A: There is no defect.
○: A level where there is a slight defect due to splashing but no problem.
Δ: Level that is somewhat acceptable but acceptable.
X: Level at which image formation is hindered due to too many defects.

From the results in Table 1, it can be seen that the information recording medium 1 to information recording medium 5 prepared in Examples 1 to 5 have high color developability and high gloss and drying properties. In addition, it can be seen that a label surface having high adhesion of the print receiving layer and few surface defects due to scattering of the coating liquid is formed.
The information recording medium 1 to the information recording medium 5 prepared in Examples 1 to 5 are compared with the information recording media 6 and 7 prepared in Comparative Example 1 and Comparative Example 2, and the amount of the antifoaming agent or leveling agent. It can be seen that a label surface with few surface defects is obtained by keeping the content of 2.6% by mass or less. In particular, in Example 3 (information recording medium 3) and Example 4 (information recording medium 4), it can be seen that by increasing the exhaust air velocity, defects due to the spray of the coating liquid are suppressed.
In the information recording medium 8 to the information recording medium 10 prepared in Comparative Examples 3 to 5, since the print receiving layer is a so-called swelling type, there are few surface defects regardless of the amount of the antifoaming agent or the leveling agent. It turns out that it is inferior in sex.

It is a schematic diagram explaining an example of the information recording medium to which this Embodiment is applied. It is a schematic diagram explaining other embodiment of an information recording medium.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Board | substrate, 11 ... Optical information recording layer, 12 ... Light reflection layer, 13 ... Protective layer, 14 ... Underlayer, 15 ... Print receiving layer, L ... Laser beam, I, II ... Information recording medium

Claims (7)

A substrate,
On the substrate, at least an optical information recording layer, an underlayer and a print receiving layer,
The underlayer contains 2.6% by mass or less of an antifoaming agent or a leveling agent,
The information recording medium, wherein the print receiving layer is a porous layer containing inorganic fine particles having an average secondary particle diameter of 500 nm or less and polyvinyl alcohol as main components.   The inorganic fine particles include wet-process silica (A) pulverized to an average secondary particle diameter of 500 nm or less, and vapor-phase process silica (B) having an average primary particle diameter of 10 nm to 20 nm, (A / B) = The information recording medium according to claim 1, wherein the information recording medium is contained in a mass ratio of (70/30) to (30/70).   The information recording medium according to claim 1, wherein the print receiving layer contains a water-soluble polyvalent metal. A method for manufacturing an information recording medium according to any one of claims 1 to 3,
A method for producing an information recording medium, wherein a print receiving layer is formed on an underlayer by spin coating.   The print receptive layer is formed by the spin coating method in an environment where the exhaust air velocity from the center of the information recording medium to the outer peripheral direction at the outer peripheral portion of the information recording medium is 4 m / s or more. The manufacturing method of the information recording medium of Claim 4. A substrate,
An optical information recording layer formed directly or via another layer on the substrate;
An underlayer and a print-receiving layer formed directly or via another layer on the opposite side of the substrate from which the laser beam is incident;
The underlayer contains an antifoaming agent or a leveling agent in the range of 0.1% by mass to 2.6% by mass,
The information recording medium according to claim 1, wherein the print receiving layer is a porous layer containing inorganic fine particles having an average secondary particle diameter of 20 nm to 500 nm as a main component and polyvinyl alcohol. A substrate,
On the substrate, at least an optical information recording layer and a print receiving layer,
The printing receiving layer is a porous layer containing inorganic fine particles having an average secondary particle diameter of 500 nm or less and polyvinyl alcohol, and is a method for producing an information recording medium,
The print receiving layer is formed by a spin coating method in an environment where an exhaust air velocity from the center of the information recording medium to the outer peripheral direction is 4 m / s or more at an outer peripheral portion of the information recording medium. A method for manufacturing an information recording medium.

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