JP2007118533A - Information recording material and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical information recording medium having a printable label layer which is good in color developing properties, gloss and drying properties of ink and is capable of recording by inkjet recording. <P>SOLUTION: The information recording medium has an optical information recording layer, a ground layer and the printable label layer on a substrate. The printable label layer comprises an inorganic fine particle with a mean secondary particle diameter of 500 nm or less and a resin binder with a keto group. The ground layer or the printable label layer comprises a crosslinking agent with at least two amino groups in a molecule. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an information recording medium having at least an optical information recording material, an undercoat layer, and a printable label layer on a substrate, and in particular, has good color development, gloss and drying properties, and is easy to store in a high temperature and high humidity environment. Thus, the present invention relates to an information recording material having good handleability for a printable label layer coating liquid and a method for producing the same.

  Currently, information recording materials having an optical information recording layer capable of optically recording and reading information, which are widely accepted in the market, include CD (compact disc) and DVD (digital versatile disc). 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 order to facilitate classification and storage of these information recording materials, or to make it easy to confirm the data contents, the contents of the recorded data are described in an index in the case. Label printing is performed on the disc itself by a printing method such as printing.

  However, label printing using the existing printing method is not a problem in mass production, but in small-volume production, it is necessary to produce a printing plate, which increases costs or changes in printing design. Each time there is a problem that workability deteriorates, such as the need to change the printing plate and perform color matching.

  In response to these problems, an information recording medium has been developed in which a printable label layer is coated on an information recording layer so that printing can be performed with an ink jet printer or a sublimation thermal transfer printer on the side opposite to the surface on which information is recorded and read by light. And are commercially available. In addition to such a printable information recording medium, for inkjet printers, as disclosed in Japanese Patent Application Laid-Open No. 5-182411, a method of printing on a label and then affixing to the information recording medium is also disclosed. However, label alignment is very complicated. In recent years, many inexpensive models that can directly print on information recording media have been put on the market, and since they are very simple to create, there are a wide variety of information recording media that can be used for inkjet printing not only for business use but also for home use. It is becoming popular.

  As the printable label layer of such an ink jet printable information recording medium, for example, Japanese Patent Application Laid-Open No. 2004-234764, Japanese Patent Application Laid-Open No. 2004-30716, Japanese Patent Application Laid-Open No. 2004-30769, Japanese Patent Application Laid-Open No. 2004-503610, and Japanese Patent Application Laid-Open No. 2001-2001. As described in JP-A-6225, JP-A-8-279179, JP-A-9-245380, etc., an ultraviolet curable resin as a main component, or a mixed formulation using an ultraviolet curable resin and an ink swellable resin in combination is used. However, these printable label layers mainly absorb the ink by utilizing the swelling of the ink-swellable resin (hereinafter referred to as the swelling type), so that the ink is absorbed by the capillary phenomenon of the recent fine voids (hereinafter referred to as the “swelling type”). Compared to ink-jet recording materials compatible with photo printing), images and fingers get dirty when touched with a finger after printing, or pasted on an index when stored in a case with an index after printing. In some cases, the duplication system for business use may print several tens to several hundreds of sheets continuously, and the media may block when stacked on the tray after printing. In other words, the so-called ink drying property was insufficient. Further, in order to avoid these problems, for example, when many pigment particles are used as exemplified in JP-A-2004-30716, the adhesion to the substrate is deteriorated, the color developability and the glossiness are increased. There was a problem such as lowering. Further, these ultraviolet curable resins have problems of safety and workability such as skin irritation and off-flavor.

On the other hand, in order to avoid the problem of such a printable label layer made of an ultraviolet curable resin, for example, Japanese Patent Application Laid-Open No. 2005-44478 discloses that an ink fixing is mainly made of a hydrophilic resin such as polyvinyl alcohol or polyvinyl acetal. Although a printable label layer with a cationic polymer mixed as an agent has been proposed, there is no problem in safety and workability because it has a hydrophilic resin as the main component, but because of the swelling type, the drying property is the same as described above. It was insufficient. In order to cope with such a problem, JP-A-2004-276298 (Patent Document 1), JP-A-2004-276299 (Patent Document 2), JP-A-2005-96258 (Patent Document 3), and JP-A-2005 No.-116072 (Patent Document 4) proposes a so-called void-type printable label layer containing at least fine particles, polyvinyl alcohol, a boron compound, and a mordant. As fine particles, gas phase method silica, pseudoboehmite, and aluminum oxide are proposed. Is described as being preferable.
However, these information recording media have good color development, gloss, and drying properties, but use a relatively low crosslinkable boron compound as a cross-linking agent for polyvinyl alcohol. When stored in a high-temperature and high-humidity environment, it becomes stuck on the index and becomes unusable, or in a commercial replication system, media are stacked and stored in a high-temperature and high-humidity environment In addition, there is a problem that the storage environment is limited due to blocking between media. In addition, there is a problem that fine cracks and cracks are likely to occur during drying unless they are dried at a relatively low temperature. Furthermore, these vapor phase silica, technical boehmite, and printable label layer coating solutions using aluminum oxide, polyvinyl alcohol, and boron compounds have low temporal stability, and the viscosity of the coating solution increases when used for a long time. There was also a problem that handling property deteriorated remarkably.
JP 2004-276298 A JP 2004-276299 A Japanese Patent Laid-Open No. 2005-96258 JP 2005-116072 A

  Accordingly, an object of the present invention is to provide an information recording material which has good color developability, gloss and drying properties, can be easily stored in a high-temperature and high-humidity environment, and has good handleability for a printable label layer coating solution. .

The above-described problems of the present application have been solved by the following means.
1. An information recording medium having at least an optical information recording layer, a base layer, and a printable label layer on a substrate, the printable label layer mainly comprising inorganic fine particles having an average secondary particle diameter of 500 nm or less and a resin binder having a keto group And a crosslinking agent having at least two primary amino groups in the molecule in at least one of the underlayer and the printable label layer.
2. 2. The information recording medium according to 1 above, wherein the resin binder having a keto group is acetoacetyl-modified polyvinyl alcohol.
3. 3. The information recording medium according to 1 or 2 above, wherein the crosslinking agent is a dihydrazide compound.
4). 4. The information recording medium as described in 1 to 3, wherein the printable label layer contains a water-soluble polyvalent metal.
5. 5. The information recording medium as described in any one of 1 to 4 above, wherein the ISO whiteness of the underlayer is 80% or more and the surface roughness Ra is 0.2 μm or less.
6). The base layer containing the cross-linking agent, or after applying and drying the cross-linking agent layer containing the cross-linking agent on the base layer, the printable label layer not containing the cross-linking agent is applied and dried. The manufacturing method of the information recording medium of any one of 1-5.

  According to the present invention, it is possible to provide an information recording material that has good color developability, gloss, and drying properties, has a high moisture bleeding property, and has good handleability for a printable label layer coating liquid, and a method for producing the information recording material.

  Hereinafter, the configuration of the information recording medium of the present invention will be described with reference to the drawings. FIG. 1 is a configuration diagram of an information recording medium of the present invention. The information recording medium of the present invention includes a substrate 10 and an optical information recording layer 11 for recording data on the substrate, a light reflecting layer 12 for reflecting a laser made of metal, a protective layer 13 for protecting the light reflecting layer, It has a structure in which a base layer 14 for improving the adhesion to the printable label layer and improving the color development and gloss of the image, and further the printable label layer 15 is laminated on the outermost layer.

  The laser irradiated during recording and reproduction is incident from the direction of the substrate opposite to the printable label layer. In addition, characters and images are recorded on the printable label layer by an inkjet printer having an inkjet recording head.

  Examples of inorganic fine particles having an average secondary particle size of 500 nm or less used for the printable label layer of the present invention include various known fine particles such as amorphous synthetic silica, alumina, alumina hydrate, calcium carbonate, magnesium carbonate, titanium dioxide. Among them, amorphous synthetic silica, alumina, or alumina hydrate is preferable in terms of color developability.

  Amorphous synthetic silica can be roughly classified into wet method silica, gas phase method silica, and others depending on the production method. Wet method silica is further classified into precipitation method silica, gel method silica, and sol method silica according to the production method. Precipitated silica is produced by reacting sodium silicate and sulfuric acid under alkaline conditions, and the silica particles that have grown are agglomerated and settled, and are then commercialized through the steps of filtration, washing, drying, pulverization and classification. Precipitated silica is commercially available, for example, from Tosoh Silica Co., Ltd. as a nip seal and from Tokuyama Co., Ltd. as a Toxeal. Gel silica is produced by reacting sodium silicate and sulfuric acid under acidic conditions. During aging, the microparticles dissolve and reprecipitate so as to bind the 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 as nip gel from Tosoh Silica Co., Ltd. and as syloid and silo jet from Grace Japan Co., Ltd. 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, it is commercially available as Snowtex from Nissan Chemical Industries, Ltd. Yes.

  Vapor phase silica is also called a dry method as opposed to a wet method, 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, but silanes such as methyltrichlorosilane and trichlorosilane can be used alone or silicon tetrachloride instead of silicon tetrachloride. Can be used in a mixed state. Vapor phase silica is commercially available as Aerosil from Nippon Aerosil Co., Ltd. and QS type from Tokuyama Co., Ltd.

The average primary particle diameter of the vapor phase silica preferably used in the present invention is preferably 30 nm or less, and preferably 15 nm or less in order to obtain higher gloss. More preferably, an average primary particle diameter of 3 to 15 nm (especially 3 to 10 nm) and a specific surface area by the BET method of 200 m ² / g or more (preferably 250 to 500 m ² / g) are used. The average primary particle diameter as used in the present invention is an average particle diameter obtained by observing the diameter of a circle equal to the projected area of each of 100 primary particles existing within a certain area by observation of fine particles with an electron microscope. The BET method referred to in the present invention is one of the powder surface area measurement methods by the vapor phase adsorption method, and is a method for obtaining the total surface area, that is, the specific surface area of a 1 g sample from the adsorption isotherm. is there. Usually, nitrogen gas is often used as the adsorbed gas, and the most frequently used method is to measure the amount of adsorption from the change in pressure or volume of the gas to be adsorbed. The most prominent expression for expressing the isotherm of multimolecular adsorption is the Brunauer, Emmett, and Teller formula, called the BET formula, 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.

  The vapor phase silica of the present invention is used in the presence of a cationic compound, the average secondary particle diameter of the vapor phase silica being 500 nm or less, preferably 10 to 300 nm, more preferably 20 to 200 nm. it can. As a dispersion method, gas phase method silica and a dispersion medium are premixed by ordinary propeller stirring, turbine type stirring, homomixer type stirring, etc., and then a media mill such as a ball mill, a bead mill, a sand grinder, a high pressure homogenizer, an ultrahigh pressure, etc. It is preferable to perform dispersion using a pressure disperser such as a homogenizer, an ultrasonic disperser, a thin film swirl disperser, or the like. The average secondary particle diameter as used in the present invention is an average particle diameter of dispersed aggregated particles observed by observing the ink receiving layer of the obtained recording material with an electron microscope. It is.

  In the present invention, wet process silica pulverized to an average secondary particle diameter of 500 nm or less can also be preferably used. The wet process silica particles used in the present invention are preferably wet process silica particles having an average primary particle diameter of 50 nm or less, preferably 3 to 40 nm, and an average aggregate particle diameter of 5 to 50 μm. It is preferable to use wet method silica fine particles finely pulverized to an average secondary particle diameter of 500 nm or less, preferably about 20 to 200 nm in the presence of.

  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 in which silica dispersed in an aqueous medium is mechanically pulverized can be preferably used. At this time, the increase in the initial viscosity of the dispersion is suppressed, high concentration dispersion is possible, and the pulverization / dispersion efficiency is increased so that the particles can be further pulverized. Therefore, the oil absorption is 210 ml / 100 g or less, the average aggregated particle diameter It is preferable to use precipitated silica of 5 μm or more. By using a high-concentration dispersion, the productivity of recording paper is also improved. The oil absorption is measured based on the description of JIS K-5101.

  As a specific method for obtaining wet method silica fine particles having an average secondary particle diameter of 500 nm or less of the present invention, first, silica particles and a cationic compound are mixed in water (whichever comes first or at the same time). And each dispersion or aqueous solution may be mixed, and at least one dispersion device such as a sawtooth blade type dispersion device, a propeller blade type dispersion device, or a rotor stator type dispersion device is used. To obtain a preliminary dispersion. If necessary, an appropriate low boiling point solvent may be added. The higher the solid content concentration of the silica pre-dispersion, the higher the concentration. However, since the dispersion becomes impossible when the concentration is too high, the preferred range is 15 to 40% by mass, more preferably 20 to 35% by mass. Next, by applying a stronger mechanical means, a wet process silica fine particle dispersion having an average secondary particle diameter 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, and a thin film swirl disperser. Can be used.

  As the cationic compound used for the dispersion of the gas phase method silica and the wet method silica, a cationic polymer or a water-soluble metal compound can be used. Examples of the cationic polymer include polyethyleneimine, polydiallylamine, polyallylamine, alkylamine polymer, JP-A-59-20696, JP-A-59-33176, JP-A-59-33177, JP-A-59-155088. JP, 60-11389, JP 60-49990, JP 60-83882, JP 60-109894, JP 62-198493, JP 63-49478, 1 described in JP-A-63-115780, JP-A-63-280681, JP-A-1-40371, JP-A-6-234268, JP-A-7-125411, JP-A-10-193976, etc. A polymer having a tertiary amino group or a quaternary ammonium base is preferably used. In particular, diallylamine derivatives are preferably used as the cationic polymer. In terms of dispersibility and dispersion viscosity, the molecular weight of these cationic polymers is preferably about 2,000 to 100,000, and particularly preferably about 2,000 to 30,000.

  Examples of the water-soluble metal compound include water-soluble polyvalent metal salts, and among them, a compound made of aluminum or a group 4A metal (for example, zirconium or titanium) in the periodic table is preferable. Particularly preferred is a water-soluble aluminum compound. As a water-soluble aluminum compound, for example, as an inorganic salt, aluminum chloride or a hydrate thereof, aluminum sulfate or a hydrate thereof, ammonium alum and the like are known. Furthermore, a basic polyaluminum hydroxide compound which is an inorganic aluminum-containing cationic polymer is known and preferably used.

The basic polyaluminum hydroxide compound has a main component represented by the following general formula 1, 2, or 3, for example, [Al ₆ (OH) ₁₅ ] ³⁺ , [Al ₈ (OH) ₂₀ ] ⁴⁺ , [Al ₁₃ (OH) ₃₄ ] ⁵⁺ , [Al ₂₁ (OH) ₆₀ ] ^3+, etc., which is a water-soluble polyaluminum hydroxide that stably contains a polynuclear condensed ion of a basic polymer. .

[Al ₂ (OH) _n Cl _6-n ] _m General formula 1
[Al (OH) ₃ ] _n AlCl ₃ general formula 2
Al _n (OH) _m Cl _(3n-m) 0 <m <3n General formula 3

  These are water treatment agents from Taki Chemical Co., Ltd. under the name of polyaluminum chloride (PAC), from Asada Chemical Co., Ltd. under the name of polyaluminum hydroxide (Paho), and from Riken Green Co., Ltd. It is marketed under the name of Purachem WT and from other manufacturers for the same purpose, and various grades can be easily obtained.

  As the water-soluble compound containing the Group 4A element of the periodic table used in the present invention, a water-soluble compound containing titanium or zirconium is more preferable. Examples of the water-soluble compound containing titanium include titanium chloride and titanium sulfate. Water-soluble compounds containing zirconium include zirconium acetate, zirconium chloride, zirconium oxychloride, hydroxy zirconium chloride, zirconium nitrate, basic zirconium carbonate, zirconium hydroxide, zirconium lactate, zirconium carbonate / ammonium, zirconium carbonate / potassium, zirconium sulfate. And zirconium fluoride compounds. In the present invention, the term “water-soluble” means that 1% by mass or more dissolves in water at room temperature and normal pressure.

  As the alumina used in the present invention, γ-alumina which is a γ-type crystal of aluminum oxide is preferable, and among them, a δ group crystal is preferable. Although γ-alumina can reduce the primary particles to about 10 nm, normally, secondary particle crystals of several thousand to several tens of thousands nm are averaged by ultrasonic waves, a high-pressure homogenizer, a counter collision type jet crusher, or the like. Those whose size is pulverized to a particle size of 500 nm or less, preferably about 20 to 300 nm can be used.

The alumina hydrate of the present invention is represented by a constitutive formula of Al ₂ O ₃ .nH ₂ O (n = 1 to 3). The case where n is 1 represents an alumina hydrate having a boehmite structure, and the case where n is greater than 1 and less than 3 represents an alumina hydrate having a pseudo boehmite structure. It can be obtained by a known production method such as hydrolysis of an aluminum alkoxide such as aluminum isopropoxide, neutralization of an aluminum salt with an alkali, hydrolysis of an aluminate. The average secondary particle diameter of the alumina hydrate used in the present invention is 500 nm or less, preferably 20 to 300 nm.

  The above-mentioned alumina and alumina hydrate used in the present invention are used in the form of a dispersion dispersed with a known dispersant such as acetic acid, lactic acid, formic acid, nitric acid and the like.

  The inorganic fine particles in the present invention are mainly contained in the printable label layer. The main component is 50% by mass or more and preferably in the range of 60 to 90% by mass with respect to the total solid content of the printable label layer.

  In the present invention, a resin binder having a keto group is used as a binder for inorganic fine particles. The resin binder having a keto group can be synthesized by a method of copolymerizing a monomer having a keto group and another monomer. Specific examples of the monomer having a keto group include acrolein, diacetone acrylamide, diacetone methacrylate, acetoacetoxyethyl methacrylate, 4-vinylacetoacetanilide, acetoacetylallylamide, and the like. Further, a keto group may be introduced by a polymer reaction. For example, an acetoacetyl group can be introduced by a reaction between a hydroxy group and a diketene. Specific examples of the resin binder having a keto group include acetoacetyl-modified polyvinyl alcohol, acetoacetyl-modified cellulose derivatives, acetoacetyl-modified starch, diacetone acrylamide-modified polyvinyl alcohol, and resin binders described in JP-A-10-157283. Can be mentioned. In the present invention, modified polyvinyl alcohol having a keto group is particularly preferable. Examples of the modified polyvinyl alcohol having a keto group include acetoacetyl-modified polyvinyl alcohol and diacetone acrylamide-modified polyvinyl alcohol.

  The acetoacetyl-modified polyvinyl alcohol can be produced by a known method such as a reaction between polyvinyl alcohol and diketene. The degree of acetoacetylation is preferably from 0.1 to 20 mol%, more preferably from 1 to 15 mol%. The saponification degree is preferably 80 mol% or more, more preferably 85 mol% or more. As a polymerization degree, the thing of 500-5000 is preferable, and the thing of 1000-4500 is especially preferable.

  Diacetone acrylamide-modified polyvinyl alcohol can be produced by a known method such as saponification of a diacetone acrylamide-vinyl acetate copolymer. As content of a diacetone acrylamide unit, the range of 0.1-15 mol% is preferable, and also the range of 0.5-10 mol% is preferable. The saponification degree is preferably 85 mol% or more, and the polymerization degree is preferably 500 to 5,000.

  In the present invention, in addition to the resin binder having a keto group, another known resin binder may be used in combination. For example, cellulose derivatives such as carboxymethyl cellulose and hydroxypropyl cellulose, starch and various modified starches, gelatin and various modified gelatins, chitosan, carrageenan, casein, soy protein, polyvinyl alcohol, various modified polyvinyl alcohols, polyvinylpyrrolidone, polyacrylamide, etc. are required It can be used together depending on the situation. Furthermore, various latexes may be used in combination as the binder resin.

  In this case, it is preferable to use a resin binder having a keto group and a highly compatible resin binder in terms of gloss. When the modified polyvinyl alcohol having a keto group is used, complete or partially saponified polyvinyl alcohol or cation-modified polyvinyl alcohol can be preferably used in combination. In particular, those having a saponification degree of 80% or more and an average polymerization degree of 200 to 5000 can be preferably used.

  Examples of the cation-modified polyvinyl alcohol include polyvinyl alcohol having a primary to tertiary amino group or a quaternary ammonium group in the main chain or side chain of polyvinyl alcohol as described in JP-A-61-110483. It is.

  The amount of the resin binder to be used in combination is not particularly limited as long as the action of the resin binder having a keto group and a crosslinking agent having two or more primary amino groups in the molecule can be obtained.

  The smaller the total content of the resin binder, the smaller the void volume in the ink receiving layer, which is preferable in terms of increasing the ink absorbency.However, if the amount is too small, the ink receiving layer becomes brittle and surface defects such as cracks increase. Since glossiness falls, the range of 5-40 mass% is preferable with respect to inorganic fine particles, and 10-30 mass% is especially preferable.

  Next, the crosslinking agent containing two or more primary amino groups in the molecule of the present invention will be described. The primary amino group of the present invention is a primary amino group bonded to a carbon atom of an aliphatic group, aromatic group or heterocyclic group, and a primary amino group bonded to a nitrogen atom (that is, a terminal amino group of hydrazine). It is. From the viewpoint of the thickening effect after mixing, a hydrazine-type amino group is preferable, and a hydrazide, semicarbazide, or carbohydrazide structure is particularly preferable. Specific examples of the compound having two or more primary amino groups bonded to carbon atoms include ethylenediamine, diethylenetriamine, triethylenediamine, metaxylenediamine, norbornanediamine, 1,3-bisaminomethylcyclohexane, and the like. Specific examples of the compound having two or more amino groups include hydrazine and salts thereof, carbohydrazide, succinic acid dihydrazide, adipic acid dihydrazide, citric acid trihydrazide, sebacic acid dihydrazide, isophthalic acid dihydrazide, and the like, Examples include a reaction product of polyisocyanate and hydrazine such as 4,4′-ethylene disemicarbazide and 4,4′-hexamethylene disemicarbazide, and a polymer hydrazide such as polyacrylic acid hydrazide. In particular, succinic acid dihydrazide and adipic acid dihydrazide are preferable in terms of water solubility and reactivity.

  The content of the compound containing two or more primary amino groups in the molecule of the present invention is not particularly limited, but in terms of productivity and the characteristics of the obtained ink receiving layer, the resin binder having a keto group is used. 0.1 to 50% by mass, and further preferably 1 to 20% by mass.

  In the present invention, other known crosslinking agents may be used in combination. When modified polyvinyl alcohol is used as the resin binder, the polyvinyl alcohol crosslinking agent includes aldehyde compounds such as formaldehyde and glutaraldehyde, ketone compounds such as diacetyl and chloropentanedione, bis (2-chloroethylurea), 2- Hydroxy-4,6-dichloro-1,3,5-triazine, a compound having a reactive halogen as described in US Pat. No. 3,288,775, divinyl sulfone, as described in US Pat. No. 3,635,718 Compounds having reactive olefins, N-methylol compounds as described in US Pat. No. 2,732,316, isocyanates as described in US Pat. No. 3,103,437, US Pat. No. 3,017,280 And aziridine compounds described in U.S. Pat. No. 2,983,611 Carbodiimide compounds as described in US Pat. No. 3,100,704, epoxy compounds as described in US Pat. No. 3,091,537, halogen carboxaldehydes such as mucochloric acid, dioxane derivatives such as dihydroxydioxane, An inorganic cross-linking agent such as a bag or zirconium sulfate can be used in combination.

  The crosslinking agent in the present invention is contained in at least one of the underlayer and the printable label layer. When it is contained in the printable label layer, it is essential to apply it before the crosslinking reaction between the resin binder and the crosslinking agent starts, so it is preferable to contain the crosslinking agent immediately before application. For this reason, coating and drying the printable label layer after applying and drying the base layer containing the cross-linking agent or the cross-linking agent layer containing the cross-linking agent on the base layer is possible. It is more preferable from the viewpoint of liquid handling properties.

  The printable label layer of the present invention preferably contains a cationic fixing agent in order to improve color developability and water resistance. As the cationic fixing agent in the present invention, the above-mentioned various cationic polymers and various polyvalent metals can be used as the cationic compound used for dispersion of the inorganic fine particles, and among them, typical examples are water-soluble aluminum compounds and water-soluble zirconium compounds. It is preferable to use a water-soluble polyvalent metal. These compounds may be any of inorganic salts, single salts and double salts of organic acids, metal complexes, and the like.

  As the water-soluble aluminum compound used in the present invention, for example, aluminum chloride or a hydrate thereof, aluminum sulfate or a hydrate thereof, ammonium alum and the like are known as inorganic salts. Furthermore, a basic polyaluminum hydroxide compound which is an inorganic aluminum-containing cationic polymer is known.

Among these water-soluble aluminum compounds, those that can be stably added to the coating solution for forming the printable label layer are preferable, and basic polyaluminum hydroxide compounds are preferably used. The main component of this compound is represented by the following formula 1, 2 or 3, for example, [Al ₆ (OH) ₁₅ ] ³⁺ , [Al ₈ (OH) ₂₀ ] ⁴⁺ , [Al ₁₃ (OH) ₃₄ ] It is a water-soluble polyaluminum hydroxide containing a basic and high-molecular polynuclear condensed ion such as ⁵⁺ , [Al ₂₁ (OH) ₆₀ ] ³⁺ , etc. stably.

[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

  These are water treatment agents under the name of polyaluminum chloride (PAC) from Taki Chemical Co., Ltd., polyaluminum hydroxide (Paho) from Asada Chemical Co., Ltd., and Riken Green Co., Ltd. It is commercially available under the name of Purachem WT and from other manufacturers for the same purpose, and various grades can be easily obtained. In the present invention, these commercially available products can be used as they are.

  The water-soluble zirconium compound used in the present invention is composed of zirconium acetate, zirconium nitrate, basic zirconium carbonate, zirconium hydroxide, zirconium carbonate / ammonium, zirconium carbonate / potassium, zirconium sulfate, zirconium fluoride, zirconium chloride, zirconium chloride octahydrate. Examples thereof include a hydrate, zirconium oxychloride, and hydroxyzirconium chloride.

  Among these water-soluble zirconium compounds, a zirconium acetate (zirconyl) compound that can be stably added to a coating solution for forming a printable label layer and exhibits excellent bleeding resistance is particularly preferable.

  These are commercially available from Daiichi Rare Element Chemical Industries, Ltd. from Zircosol ZA-20, etc., or Nippon Light Metal Co., Ltd.

  The total addition amount of the water-soluble aluminum compound and the water-soluble zirconium compound is preferably 10% by mass or less, more preferably 0.5 to 8% by mass with respect to the inorganic fine particles. The content ratio of the water-soluble aluminum compound and the water-soluble zirconium compound is preferably in the range of 10: 1 to 1:10.

  The printable label layer in the present invention preferably contains at least one selected from a polymer latex having an average particle diameter of 100 nm or less and a glass transition temperature TG of 40 degrees or less and an alkanediol having 3 to 5 carbon atoms. By containing these, while maintaining the color development, gloss, and drying properties of the printable label layer, the shrinkage variation of the coating layer due to the drying shrinkage rate and temperature / humidity fluctuation of the printable label layer is suppressed, and information is recorded and reproduced. The error of time can be avoided.

  The polymer latex in the present invention is a polymer latex polymerized by an emulsion polymerization method, for example, styrene-butadiene copolymer latex, polyacrylate ester latex, polymethacrylate ester latex, vinyl acetate latex, ethylene- Vinyl acetate latex is preferably used.

  The average particle size of the polymer latex is preferably 100 nm or less and the glass transition temperature TG is preferably 40 degrees or less. When the average particle diameter of the polymer latex exceeds 100 nm, the transparency of the printable label layer is deteriorated and the color developability is deteriorated or the gloss is lowered, which is not preferable. When the glass transition temperature TG exceeds 40 ° C., The plasticizing effect of the printable label layer is lowered, and it becomes difficult to suppress the shrinkage variation of the coating layer due to the drying shrinkage rate and temperature / humidity change of the printable label layer.

  The polymer latex is preferably used in an amount of 5 to 30% by weight, more preferably 5 to 20% by weight, based on the wet silica contained in the printable label layer. If it is less than 5% by weight, the effect of suppressing the shrinkage fluctuation of the coating layer is insufficient, and if it exceeds 30% by weight, the ink absorbency tends to decrease.

  The C3-C5 alkanediol of the present invention is liquid at room temperature, has high hygroscopicity, low volatility, and is water-soluble. The compound can suppress the curling fluctuation of the substrate by suppressing the shrinkage fluctuation of the coating layer due to the temperature and humidity fluctuations without causing the deterioration of color developability and cracking, and the stable information recording and reproducing performance of the information recording medium. Is obtained.

  Examples of the alkanediol having 3 to 5 carbon atoms include propanediol, butanediol, and pentanediol, and all of these isomers are included. Also included are branched butanediols 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. Propanediol includes propylene glycol (1,2-propanediol) and trimethylene glycol (1,3-propanediol), with propylene glycol being particularly preferred. The amount of the compound added is preferably from 0.1 to 50% by weight, more preferably from 1 to 20% by weight, based on the inorganic fine particles.

  The information recording medium of the present invention may have an overcoat layer on the printable label layer. With the overcoat layer, the surface strength can be further improved, and the storage stability of the image can be improved. The overcoat layer needs to have a property of accepting ink or transmitting it quickly. The layer thickness of the surface layer is preferably 0.01 to 1000 μm, more preferably 0.1 to 100 μm.

  The coating method of the printable label layer of the present invention is not particularly limited, and a known coating method can be used. 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, etc. can be used as appropriate, but they should be formed by a screen printing method from the viewpoint of productivity. Is preferred.

In the present invention, the dry water content when the printable label layer is applied is preferably 120 g / m ² or less. By adjusting the dry moisture content within such a range, an information recording medium free from errors during information recording and reproduction can be obtained. In the present invention, the dry water content is the water content per unit area in the printable label layer to be applied and dried.

The dry coating amount of the printable label layer in the present invention is 12 to 28 g / m ² , preferably 12 to 25 g / m ² , and more preferably 14 to 23 g / m ² . When the dry coating amount is less than 12 g / m ² , the drying property is lowered, and when it exceeds 28 g / m ² , an error during information recording and reproduction is likely to occur due to the weight of the printable label layer.

  The drying temperature of the printer label layer in the present invention is preferably 30 to 60 ° C, more preferably 40 to 60 ° C. If it is less than 30 ° C., it is not preferable because the drying time becomes longer and the production efficiency deteriorates. If it exceeds 60 ° C., the quality of the optical information recording layer having low heat resistance deteriorates, and errors occur during information recording and reproduction. Therefore, it is not preferable.

  In the present invention, it is possible to provide an under layer 14 having an ISO whiteness of 80% or more and a surface roughness Ra of 0.2 μm or less under the printable label layer 15 to achieve high color development such as photographic printing paper. Is preferable because it is possible to obtain high brightness and gloss. Furthermore, it is preferable that the ISO whiteness is 90% or more and the surface roughness Ra is 0.15 μm or less.

  The ISO whiteness in the present invention is the whiteness defined by ISO2470, and the surface roughness Ra is Ra (center surface average roughness) defined in JIS-B0601: 2001. Ra is a measured value of a stylus type surface roughness meter, and is measured with a reference length of 8 mm. When determining Ra, the reference length is extracted from a portion where there is no extraordinary high mountain or deep valley that can be regarded as a scratch. When the surface shape has directionality, the measurement is performed in the direction in which Ra is the largest.

  As described above, the underlayer in the present invention can contain a crosslinking agent having two or more primary amino groups in the molecule.

  Any known method may be used for forming such an underlayer, but it is preferable to form a known radiation curable resin by screen printing from the viewpoint of productivity. 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. Among them, ultraviolet rays and electron beams are preferable.

  When the radiation curable resin is formed by screen printing, a time for leveling the resin after printing is necessary as appropriate from the viewpoint of smoothness of the information recording medium.

  As a film thickness of a base layer, 0.1-100 micrometers is preferable, 1-50 micrometers is more preferable, and 3-20 micrometers is the most preferable.

  As the substrate 10, various materials used as substrate materials for conventional optical recording media that are transparent to the wavelengths of the recording light and the reproducing light can be arbitrarily selected and used. Specific examples include acrylic resins such as polycarbonate and polymethyl methacrylate, vinyl chloride resins such as polyvinyl chloride and vinyl chloride copolymers, epoxy resins, amorphous polyolefin, polyester, metals such as aluminum, and the like. If desired, these may be used in combination. Among the above materials, amorphous polyolefin and polycarbonate are preferable, and polycarbonate is particularly preferable from the viewpoint of chemical resistance, dimensional stability, light transmittance, and low cost. Further, the thickness of the substrate is preferably 0.5 to 1.2 mm, and more preferably 0.6 to 1.1 mm. Further, the substrate is provided with unevenness (pregroove) representing information such as a tracking guide groove or an address signal. The pitch, depth (groove depth), and half width of the pre-group can be arbitrarily set depending on the type of information recording medium.

  In the information recording medium of the present invention, as described above, the optical information recording layer, the light reflecting layer, and the protective layer are provided between the substrate and the base layer. In the present invention, the optical information recording layer and the light reflecting layer are indispensable as an information recording medium. However, regarding the protective layer, if there is a base layer having both functions of the protective layer and the base layer, it is not always necessary to provide it. Absent.

  The optical information recording layer 11 is provided on the substrate 10 and is formed of a material capable of recording digital information by irradiation with laser light. Usually, it is formed as an optical information recording layer made of an organic dye as represented by CD-R or DVD-R, or as an optical information recording layer made of an inorganic material as represented by CD-RW or DVD-RW. The

  The optical information recording layer made of an organic dye is provided using a dry thin film forming method such as a vacuum deposition method or a sputtering method, or a wet thin film forming method such as a cast method, a spin coating method, or an immersion method. Among them, the spin coating method is particularly preferable from the viewpoint of mass productivity and cost. As a specific method, an organic dye as a recording material is dissolved in a suitable solvent together with a binder or the like to prepare a coating solution, and this coating solution is then applied to a surface on which a substrate pregroove is formed by spin coating. After coating to form a coating film, it is formed by drying. The temperature at the time of applying the spin coating method is preferably 25 to 60 ° C., more preferably 30 to 50 ° C. from the viewpoint of productivity and heat resistance of the dye.

  Examples of the organic dyes include cyanine dyes, oxonol dyes, metal complex dyes, azo dyes, and phthalocyanine dyes. Among these, phthalocyanine dyes are preferable because of excellent light resistance and durability. JP-A-4-74690, JP-A-8-127174, JP-A-11-53758, JP-A-11-334204, JP-A-11-334205, JP-A-11-334206, The dyes described in JP-A-11-334207, JP-A-2000-43423, JP-A-2000-108513, JP-A-2000-158818, and the like are also preferably used.

  Solvents for the coating solution of the optical information recording layer made of organic dyes include butyl acetate, ethyl lactate, 2-methoxyethyl acetate, methyl ethyl ketone, cyclohexanone, methyl isobutyl ketone, dichloromethane, 1,2-dichloroethane, chloroform, dimethylformamide, methylcyclohexane. , Ethers such as tetrahydrofuran, ethyl ether, dioxane, alcohols such as ethanol, n-propanol, isopropanol, n-butanol diacetone alcohol, 2,2,3,3-tetrafluoropropanol, ethylene glycol monomethyl ether, ethylene glycol monoethyl Examples include ether and propylene glycol monomethyl ether. The above solvents can be used alone or in combination of two or more in consideration of the solubility of the recording material used. Various additives such as a binder, an antioxidant, a UV absorber, a plasticizer, and a lubricant may be further added to the coating solution depending on the purpose.

  Examples of the binder include gelatin, cellulose derivative, dextran, rosin, rubber, polyethylene resin, polypropylene resin, polystyrene resin, polyisobutylene resin, polyvinyl chloride resin, polyvinylidene chloride resin, polyvinyl chloride / polyvinyl acetate copolymer Examples include coalesced resins, polymethyl acrylate resins, polymethyl methacrylate resins, polyvinyl alcohol, chlorinated polyethylene resins, epoxy resins, butyral resins, rubber derivatives, and phenol / formaldehyde resins. When a binder is used in combination as a material for the optical information recording layer, the amount of the binder used is generally in the range of 0.01 to 50 solids by mass with respect to the organic dye, preferably 0.1 to 5 solids. It is the range of mass multiplication amount. Thus, the density | concentration of the organic pigment | dye in the coating liquid prepared is generally in the range of 0.01 to 10 solids by mass, and preferably in the range of 0.1 to 5 solids by mass.

  The optical information recording layer can contain various anti-fading agents represented by singlet oxygen quenchers in order to improve the light resistance of the optical information recording layer. As the antifading agent, a singlet oxygen quencher is generally used. The amount of anti-fading agent such as singlet oxygen quencher used is usually in the range of 0.1 to 50 solids mass%, preferably 0.5 to 45 solids mass%, based on the amount of organic dye. More preferably, it is the range of 3-40 mass% of solid content.

  The optical information recording layer made of an inorganic substance is formed using a vapor deposition method, an ion plating method, a sputtering method, or the like. Among these, the sputtering method is particularly preferable from the viewpoint of mass productivity and cost.

  The inorganic substance is preferably a phase change type optical recording material composed of at least Ag, Al, Te, and Sb that can take at least two states of a crystalline state and an amorphous state. A known dielectric layer is formed on the optical information recording layer as necessary.

  The optical information recording layer in the present invention may be a single layer or a multilayer, and the layer thickness varies depending on the type of the optical information recording layer, but is generally in the range of 20 to 500 nm, preferably in the range of 30 to 300 nm, more preferably The range is 50 to 100 nm.

  The light reflecting layer 12 is provided on the optical information recording layer 11 and is provided for reflecting the laser light normally irradiated from the substrate 10 side to the substrate side. After forming the optical information recording layer, a light reflecting material is deposited on the optical information recording layer by vapor deposition, sputtering or ion plating to form a light reflecting layer. In forming the light reflection layer, a mask is usually used, and the formation region of the light reflection layer can be adjusted thereby.

  For the light reflecting layer, a light reflecting material having a sufficiently high reflectivity with respect to laser light is used. The reflectance is preferably 70% or more. As a light reflective material having a high reflectance, Mg, Se, Y, Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W, Mn, Re, Fe, Co, Ni, Ru, Rh, Pd , Ir, Pt, Cu, Ag, Au, Zn, Cd, Al, Ga, In, Si, Ge, Te, Pb, Po, Sn, Bi, and other metals and semi-metals or stainless steel. These light reflecting materials may be used alone, or may be used in combination of two or more kinds or as an alloy. Among these, Cr, Ni, Pt, Cu, Ag, Au, Al, and stainless steel are preferable. From the viewpoint of cost and reflectance, Au, Ag, Al, or an alloy thereof is particularly preferable, and Au, Ag, or an alloy thereof is most preferable.

  The thickness of the light reflecting layer is generally in the range of 10 to 300 nm, and preferably in the range of 50 to 200 nm.

  The protective layer 13 is formed on the light reflecting layer 12 by a casting method, a spin coating method, a screen printing method, or the like. In particular, by applying the spin coating method, damage to the optical information recording layer (dissolution of dye, The protective layer can be formed without giving a chemical reaction between the dye and the protective layer material. If a radiation curable resin (ultraviolet curable resin) is used for the protective layer, after the protective layer is formed, the ultraviolet curable resin is cured by irradiating ultraviolet rays from above the protective layer with an ultraviolet irradiation lamp (metal halide lamp). Let Further, in order to eliminate the thickness unevenness of the protective layer to be formed, a treatment such as leaving it for a certain period of time before curing the resin may be appropriately performed.

  The protective layer prevents moisture from entering and scratching. The material constituting the protective layer is preferably a radiation curable resin, a visible light curable resin, a thermosetting resin, silicon dioxide, or the like, and more preferably a radiation curable resin. As the radiation curable resin, for example, various ultraviolet curable resins such as “SD-640” manufactured by Dainippon Ink & Chemicals, Inc. can be used.

  The thickness of the protective layer is preferably in the range of 1 to 200 μm, and more preferably in the range of 50 to 150 μm.

As described above, an information recording medium comprising a laminate in which an optical information recording layer, a light reflecting layer, a protective layer, a base layer, and a printable label layer are sequentially provided on a substrate is produced.
The information recording medium of the present invention is used because the track pitch of the pregroove formed on the substrate and the material constituting the optical information recording layer are appropriately set, so that the track pitch is narrower than that of a conventional DVD or the like. The present invention can also be applied to an information medium in which information can be recorded / reproduced with a laser beam having a wavelength smaller than the laser beam.

  Hereinafter, examples will be shown to describe the present invention more specifically, but the present invention is not limited to these examples, and various applications can be made within the scope of the claims. In the description, “parts” and “%” refer to parts by mass of total solids and mass% of total solids.

−Preparation of information recording media before application of printable label layer−
A polycarbonate resin substrate having a thickness of 1.2 mm and a groove having a width of 0.45 μm and a depth of 155 nm was produced by injection molding. 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: SD318, manufactured by Dainippon Ink & Chemicals, Inc.) is applied onto the light reflecting layer by spin coating, and cured by irradiating with ultraviolet rays using a high-pressure mercury lamp. A protective layer having a thickness of 5 μm was formed. Thereafter, ultraviolet curable ink (trade name: SSD F27, manufactured by Dainippon Ink & Chemicals, Inc.) was printed by screen printing, and after 20 seconds, cured by irradiating with ultraviolet rays using a high-pressure mercury lamp. An underlayer was formed. The information recording medium 1 before coating of the printable label layer comprising the substrate, the optical information recording layer, the light reflecting layer, the protective layer, and the base layer was produced by the above steps. The ISO whiteness of the information recording medium 1 before application of the printable label layer was 92%, and the surface roughness Ra was 0.12.

-Formation of printable label layer-
After adding 4 parts of dimethyldiallylammonium chloride homopolymer (molecular weight 9,000) and 100 parts of vapor phase silica (average primary particle diameter 7 nm, specific surface area 300 m ² / g) to water to prepare a preliminary dispersion, a high-pressure homogenizer To prepare a silica dispersion 1 having a solid content concentration of 20%.

<Printable label layer formulation 1>
Silica dispersion 1 (as silica solid content) 100 parts Acetoacetyl-modified polyvinyl alcohol 22 parts (Acetyacetylation degree 3%, Saponification degree 98%, Average polymerization degree 2500)
2.2 parts of adipic acid dihydrazide Thereafter, a printable label layer coating solution having a solid content concentration of 15% was prepared with the above-described printable label layer formulation 1 so that the solid content coating amount was 18 g / m ^2. The information recording medium 1 before coating was applied by a rod bar method, dried by blowing air at 50 ° C., and the information recording medium of Example 1 was produced. At this time, adipic acid dihydrazide was added immediately before coating, the dry water content was 102 g / m ² , and the average secondary particle diameter of the vapor phase method silica was 80 nm as observed by electron microscope.

A crosslinker layer coating solution having a solid content concentration of 10% is prepared in the following crosslinker layer formulation 1 so that the solid content coating amount is 0.5 g / m ^2. It was applied by a rod bar method and dried by blowing air at 50 ° C. Then, a printable label layer coating solution having a solid content concentration of 15% was prepared with the following printable label layer formulation 2 and applied to the cross-linking agent layer by a rod bar method so that the solid content coating amount was 18 g / m ² . The information recording medium of Example 2 was manufactured by blowing air at 50 ° C. and drying. At this time, the dry water content of the printable label layer was 102 g / m ² , and the average secondary particle size of the vapor phase method silica was 80 nm as observed by an electron microscope.

<Crosslinking agent layer formulation 1>
46 parts of polyvinyl alcohol (saponification degree 88%, average polymerization degree 500)
54 parts of adipic acid dihydrazide

<Printable label layer 2>
Silica dispersion 1 (as silica solid content) 100 parts Acetoacetyl-modified polyvinyl alcohol 22 parts (Acetyacetylation degree 3%, Saponification degree 98%, Average polymerization degree 2500)

  An information recording medium of Example 3 was produced in the same manner as in Example 2 except that the printable label layer composition 2 of Example 2 was changed to the following printable label layer composition 3.

<Printable label layer composition 3>
Silica dispersion 1 (as silica solid content) 100 parts Acetoacetyl-modified polyvinyl alcohol 22 parts (Acetyacetylation degree 3%, Saponification degree 98%, Average polymerization degree 2500)
3 parts of basic polyaluminum hydroxide (Purechem WT manufactured by Riken Green)

  An information recording medium of Example 4 was produced in the same manner as in Example 2 except that the printable label layer composition 2 of Example 2 was changed to the following printable label layer composition 4.

<Printable label layer composition 4>
Silica dispersion 1 (as silica solid content) 100 parts Diacetone acrylamide modified polyvinyl alcohol 22 parts (Diacetone acrylamide modification degree 5 mol%, saponification degree 98 mol%, polymerization degree 1700)
3 parts of basic polyaluminum hydroxide (Purechem WT manufactured by Riken Green)

  An information recording medium of Example 5 was produced in the same manner as in Example 2 except that the crosslinking agent formulation 2 of Example 2 was changed to the following crosslinking agent formulation 2.

<Crosslinking agent layer formulation 2>
46 parts of polyvinyl alcohol (saponification degree 88%, average polymerization degree 500)
54 parts of succinic acid dihydrazide

  The pre-printable label layer information recording medium 2 was prepared in the same manner as the pre-printable label layer information recording medium 1 except that the base layer of the pre-printable label layer information recording medium 1 was formed to be 5 μm. did. Subsequently, an information recording medium of Example 6 was produced in the same manner as in Example 2 except that the information recording medium 2 before application of the printable label layer was used. In addition, the ISO whiteness of the information recording medium 2 before application of the printable label layer was 78%, and the surface roughness Ra was 0.14.

  The printable label layer is the same as the information recording medium 1 before application of the printable label layer except that the time from the screen printing of the underlayer of the information recording medium 1 before application of the printable label layer to the irradiation of ultraviolet rays is set to 5 seconds. A pre-coating information recording medium 3 was produced. Subsequently, an information recording medium of Example 7 was produced in the same manner as in Example 2 except that the information recording medium 3 before application of the printable label layer was used. Note that the ISO whiteness of the information recording medium 3 before application of the printable label layer was 92%, and the surface roughness Ra was 0.22.

  Add nitric acid (2 parts) and boehmite alumina hydrate (average primary particle size 14 nm) 100 parts to water and use a sawtooth blade type disperser to prepare an alumina hydrate dispersion with a solid content of 30%. Adjusted.

<Printable label layer formulation 5>
Alumina hydrate dispersion (as alumina hydrate solid content) 100 parts Acetacetyl-modified polyvinyl alcohol 13 parts (Acetyacetylation degree 3%, Saponification degree 98%, Average polymerization degree 2500)
Basic polyaluminum hydroxide 2 parts (Purechem WT manufactured by Riken Green)
Then, a printable label layer coating solution having a solid content concentration of 25% was prepared with the above-mentioned printable label layer formulation 5 so that the solid coating amount was 24 g / m ² . The information recording medium 1 before application of the layer was applied by the rod bar method, dried by blowing air at 50 ° C., and the information recording medium of Example 8 was produced. At this time, the dry water content was 72 g / m ² , and the average secondary particle size of the alumina hydrate was 100 nm as observed with an electron microscope.

  4 parts of dimethyldiallylammonium chloride homopolymer (molecular weight 9,000) and 100 parts of wet process silica (oil absorption 200 ml / 100 g, average primary particle diameter 16 nm, average aggregated particle diameter 9 μm) are added to water, and a sawtooth blade type A preliminary dispersion was prepared using a disperser (blade peripheral speed 30 m / sec). Next, the obtained preliminary dispersion was treated with a bead mill to prepare a silica dispersion 2 having a solid concentration of 30%.

<Printable label layer composition 6>
Silica dispersion 2 (as silica solid content) 100 parts Acetoacetyl-modified polyvinyl alcohol 22 parts (Acetyacetylation degree 3%, Saponification degree 98%, Average polymerization degree 2500)
3 parts of basic polyaluminum hydroxide (Purechem WT manufactured by Riken Green)
Thereafter, a printable label layer coating solution having a solid content concentration of 20% with the above-mentioned printable label layer formulation 6 was prepared so that the solid content coating amount was 18 g / m ² . The information recording medium 1 before application of the layer was applied by the rod bar method, dried by blowing air at 50 ° C., and the information recording medium of Example 9 was produced. At this time, the dry water content was 72 g / m ² , and the average secondary particle size of the wet process silica was 100 nm as observed with an electron microscope.

(Comparative Example 1)
A printable label layer coating solution having a solid content concentration of 12% with the printable label layer formulation 7 shown below is prepared, and the information bar 1 is applied to the information recording medium 1 before coating the printable label layer so that the solid content coating amount is 18 g / m ^2. The information recording medium of Comparative Example 1 was produced by coating by the method, drying by blowing air at 50 ° C. At this time, the dry moisture content of the printable label layer was 132 g / m ² , and the average secondary particle diameter of the vapor phase method silica was 80 nm as observed by an electron microscope.

<Printable label layer formulation 7>
Silica dispersion 1 (as silica solid content) 100 parts Unmodified polyvinyl alcohol 23 parts (saponification degree 88%, average polymerization degree 3500)
4 parts boric acid

(Comparative Example 2)
An information recording medium of Comparative Example 8 was produced in the same manner as in Example 2 except that the printable label layer formulation 2 of Example 2 was changed to the following printable label layer formulation 8.

<Printable label layer formulation 8>
Silica dispersion 1 (as silica solid content) 100 parts Unmodified polyvinyl alcohol 23 parts (saponification degree 88%, average polymerization degree 3500)

(Comparative Example 3)
An information recording medium of Comparative Example 9 was produced in the same manner as in Example 1 except that adipic acid hydrazide was removed from the printable label layer formulation 1 of Example 1.

(Comparative Example 4)
An information recording medium of Comparative Example 4 was produced in the same manner as in Example 2 except that the crosslinking agent layer formulation 1 of Example 2 was changed to the following crosslinking agent layer formulation 3.

<Crosslinking agent layer formulation 3>
46 parts of unmodified polyvinyl alcohol (saponification degree 88%, average polymerization degree 500)
54 parts of propionic acid hydrazide

(Comparative Example 5)
An information recording medium of Comparative Example 5 was produced in the same manner as in Example 9 except that the wet silica pre-dispersion was directly used for blending the printable label layer. In addition, the average secondary particle diameter of the preparatory dispersion of the wet process silica was 800 nm as observed with an electron microscope.

(Comparative Example 6)
An information recording medium of Comparative Example 6 was produced in the same manner as in Example 1 except that the printable label layer formulation 1 of Example 1 was changed to the following printable label layer formulation 9.

<Printable label layer combination 9>
Silica dispersion 1 (as silica solid content) 40 parts Acetoacetyl-modified polyvinyl alcohol 57 parts (Acetyacetylation degree 3%, Saponification degree 98%, Average polymerization degree 2500)
Adipic acid dihydrazide 3 parts

  Each of the obtained information recording media was evaluated as follows. The results are shown in Table 1.

<Color development>
Using a commercially available inkjet printer capable of optical disc label printing (manufactured by Seiko Epson Corporation, PMG800), print a person and a landscape image on the surface of the printable label layer, and compare with the silver salt photograph produced using the image, the following criteria The color developability was visually evaluated.
(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 disc label printing (manufactured by Seiko Epson Corporation, PMG800), print a person and a landscape image on the surface of the printable label layer, and compare with the silver salt photograph produced using the image, the following criteria The gloss was visually evaluated.
A: Higher gloss than silver salt photograph.
○: 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 (Seiko Epson, PMG800), solid prints of red, blue, green, and black are made on the surface of the printable label layer. The amount of ink that was crimped and transferred to PPC paper was visually observed. Overall evaluation was made according to the following criteria.
○: Not transferred at all.
Δ: Transfer and difficult to use.
X: Most of the images are transferred and cannot be used.

<Storage in high temperature and high humidity environment>
The obtained information recording medium in the case together with the index and the 10 stacked ones are stored in a high temperature and high humidity environment of 40 ° C. and 85% RH for 24 hours. Evaluated.
◯: Good because there is no sticking between the index, the information recording medium, and the information recording medium.
Δ: Level where sticking occurs and becomes a problem.
X: Level at which significant sticking occurs and becomes a problem.

<Handling properties of coating liquid>
Each printable label layer coating solution was stored at room temperature for one week, the coating solution viscosity before and after storage was measured, and evaluated according to the following criteria. In addition, when adding adipic acid hydrazide immediately before application | coating, the coating liquid before addition was used.
○: There is almost no change in viscosity before and after storage, and the handling properties of the coating liquid are good.
X: The viscosity is remarkably increased after storage, and the handling property of the coating liquid is extremely poor.

From the results shown in Table 1, the information recording medium of the present invention has good color development, gloss and drying properties, is easy to store in a high-temperature and high-humidity environment, and has good handleability for the printable label layer coating solution. I understand. Further, it can be seen from Examples 2 and 3 that the color developability is improved particularly when the printable label layer contains a water-soluble polyvalent metal. Furthermore, from Examples 3, 6 and 7, if the ISO whiteness of the underlayer is 80% or more and the surface roughness Ra is 0.2 μm or less, the color development and glossiness may be further improved. I understand.
On the other hand, since the information recording medium of Comparative Example 1 used unmodified polyvinyl alcohol as a resin binder and boric acid as a cross-linking agent, storage under a high temperature and high humidity environment became a problem, and the handling property of the coating liquid was inferior. Further, the information recording medium of Comparative Example 2 contained a crosslinking agent having two or more primary amino groups in the molecule, but because unmodified polyvinyl alcohol was used, the crosslinking reaction did not proceed and fine cracks were generated. Therefore, gloss and color developability are poor, and storage in a high temperature and high humidity environment has been a problem. Further, the information recording medium of Comparative Example 3 contained a resin binder having a keto group, but did not contain a crosslinking agent having two or more primary amino groups in the molecule. Cracks occurred and gloss and color developability were poor, and storage in a high temperature and high humidity environment was a problem. Further, since the information recording medium of Comparative Example 4 uses a crosslinking agent having only one primary amino group in the molecule, the crosslinking reaction does not proceed, and fine cracks are generated, resulting in glossiness and color development. Inferior, storage in a high temperature and high humidity environment was a problem. In addition, since the information recording medium of Comparative Example 5 used inorganic fine particles having an average secondary particle diameter exceeding 500 nm, the glossiness and color developability were inferior. Further, since the information recording medium of Comparative Example 6 did not contain inorganic fine particles as a main component, the ink overflowed and the coloring property and the drying property were inferior.

It is explanatory drawing which showed the structure of the 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 Printable label layer

Claims (6)

  An information recording medium having at least an optical information recording layer, a base layer, and a printable label layer on a substrate, the printable label layer mainly comprising inorganic fine particles having an average secondary particle diameter of 500 nm or less and a resin binder having a keto group And a crosslinking agent having at least two primary amino groups in the molecule in at least one of the underlayer and the printable label layer.   The information recording medium according to claim 1, wherein the resin binder having a keto group is acetoacetyl-modified polyvinyl alcohol.   The information recording medium according to claim 1, wherein the crosslinking agent is a dihydrazide compound.   The information recording medium according to claim 1, wherein the printable label layer contains a water-soluble polyvalent metal.   The information recording medium according to any one of claims 1 to 4, wherein the ISO whiteness of the underlayer is 80% or more and the surface roughness Ra is 0.2 µm or less.   The base layer containing the cross-linking agent, or the coatable label layer not containing the cross-linking agent is applied and dried after the cross-linking agent layer containing the cross-linking agent is applied and dried on the base layer. Item 6. The method for producing an information recording medium according to any one of Items 1 to 5.

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