JP2015224047A - Packaging material, and recording medium package comprising recording medium hermetically sealed with packaging material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a packaging material which can suppress the yellow discoloration of a packaged recording medium.SOLUTION: A packaging material hermetically seals a recording medium comprising base material, and an ink receiving layer comprising inorganic particles and binder. The packaging material has an oxygen permeability of 15.0 cc 20 μm/mday atom or less.

Description

  The present invention relates to a packaging material and a recording medium package in which a recording medium is hermetically packaged with the packaging material.

  For the purpose of maintaining the quality of the recording medium, the recording medium used in the ink jet recording method or the like is distributed in the market as a recording medium package that is hermetically packaged with a packaging material. As a packaging material, a material using a resin having flexibility and excellent transparency and heat resistance is generally used. Specific examples of the resin used for the packaging material include soft polyvinyl chloride, soft polyvinylidene chloride, polypropylene, and polyethylene.

  Patent Document 1 describes a recording medium package in which a recording medium having an ink receiving layer is packaged with a packaging material made of high-density polyethylene.

  Patent Document 2 describes a recording medium package in which a recording medium having a base material and an ink receiving layer containing inorganic particles and a thioether compound is packaged with a packaging material made of a polylactic acid resin.

JP-A-8-282746 JP 2008-037442 A

  According to the study by the present inventors, it has been found that in the packaging materials described in Patent Documents 1 and 2, the packaged recording medium may turn yellow.

  Accordingly, an object of the present invention is to provide a packaging material capable of suppressing yellowing of the recording medium packaged, and a recording medium package in which the recording medium is hermetically packaged with the packaging material.

The above object is achieved by the present invention described below. That is, the packaging material according to the present invention is a packaging material for hermetically packaging a recording medium having a substrate and an ink receiving layer containing inorganic particles and a binder, and has an oxygen permeability of 15.0 cc · 20 μm / m. ² · day · atom or less.

  ADVANTAGE OF THE INVENTION According to this invention, the recording material which can suppress yellowing of the recording medium currently packaged, and the recording medium package which sealed-packed the recording medium with the packaging material which concerns can be provided.

  Hereinafter, the present invention will be described in detail with reference to preferred embodiments.

  The inventors first studied the mechanism of yellowing of a recording medium having a substrate and an ink receiving layer containing inorganic particles and a binder.

  A recording medium having an ink receiving layer containing inorganic particles and a binder has a porous ink receiving layer. And the fine hole in an ink receiving layer tends to adsorb | suck the substance which exists in an environment. Therefore, the ink receiving layer adsorbs phenolic antioxidants such as butylated hydroxytoluene (BHT) present in the environment, and the phenolic antioxidants are nitrated by nitrogen oxides (NOx) in the air. The recording medium turns yellow by being oxidized by oxygen or exhibiting a yellow color. BHT is widely used as an antioxidant for plastics and the like, and can sublimate and diffuse into the air, so that it may be adsorbed on the recording medium during the manufacturing process, transportation and storage process of the recording medium. Conceivable.

  When the packaging material described in Patent Documents 1 and 2 is used, yellowing of the recording medium is suppressed as compared with the case where packaging is not performed, but the required level has not been reached. This is considered to be due to the fact that the packaging material has high air permeability, and therefore, when the storage period is long, NOx and oxygen gradually permeate to cause yellowing.

Therefore, the present inventors have arrived at the present invention in which the recording medium is hermetically packaged with a low air-permeable packaging material. Specifically, by using a packaging material having an oxygen permeability of 15.0 cc · 20 μm / m ² · day · atom or less, NOx and oxygen permeation can be prevented even when the storage period is long, and the packaging record It was found that yellowing of the medium can be suppressed. Further, the oxygen permeability of the packaging material is preferably 10.0 cc · 20 μm / m ² · day · atom, more preferably 5.0 cc · 20 µm / m ² · day · atom or less, and 2.0 cc · 20 µm / m. ² · day · atom or less is particularly preferable. In the present invention, “oxygen permeability” means a value measured under conditions of a temperature of 20 ° C. and a relative humidity of 0% based on JIS K 7126.

Examples of the material having an oxygen permeability of 15.0 cc · 20 μm / m ² · day · atom or less include an ethylene-vinyl alcohol copolymer film, a polyacrylonitrile film, and a polyvinyl alcohol film.

Furthermore, in this invention, it is preferable that the water vapor permeability of a packaging material is also low. Although the pH of the ink receiving layer may change due to water vapor (humidity) and yellowing may occur easily, the low water vapor permeability can alleviate the influence of water vapor. Specifically, the water vapor permeability is preferably 20 g / m ² · day or less, and more preferably 10 g / m ² · day or less. In the present invention, “water vapor permeability” means a value measured on a 30 μm film under the conditions of a temperature of 40 ° C. and a relative humidity of 90% based on JIS K 7129: 2008. Examples of the material having a low water vapor permeability include low density polyethylene, high density polyethylene, and polypropylene. However, these materials have high oxygen permeability and may not satisfy the conditions of the present invention (15.0 cc · 20 μm / m ² · day · atom or less). Therefore, a film having a multilayer structure using the above-described material having an oxygen permeability of 15.0 cc · 20 μm / m ² · day · atom or less and a material having a low water vapor permeability is preferable. For example, a multilayer film of an ethylene-vinyl alcohol copolymer and high-density polyethylene has an oxygen permeability of 15.0 cc · 20 μm / m ² · day · atom or less and a water vapor permeability of 20 g / m ² · day or less. is there. As a method for producing a multilayer film, a conventionally known method (for example, a co-extrusion method, a lamination method, a heat sealing method, etc.) can be used.

  Further, the thickness of the packaging material is preferably 40 μm or more and 100 μm or less from the viewpoint of workability and strength when packaging.

  In the present invention, the packaging material hermetically wraps the recording medium. A conventionally known method can be used as the method for hermetic packaging.

  As in the above mechanism, the effects of the present invention can be achieved by the synergistic effects of the components. For example, after packing a recording medium into a packaging material, a method including heat sealing and a chuck that can be opened and closed may be used.

  Further, the inner volume of the packaging material after the recording medium is hermetically packaged is preferably 2.0 times or less, more preferably 1.5 times or less with respect to the volume of the packaged recording medium. The ratio is particularly preferably 1.25 times or less. By reducing the internal volume, it is possible to reduce the amount of air contained in the package when sealed, and particularly effectively suppress yellowing of the recording medium.

  Hereinafter, a recording medium that is hermetically packaged with a packaging material will be described.

[recoding media]
The recording medium of the present invention has a base material and an ink receiving layer containing inorganic particles and a binder. In the present invention, an inkjet recording medium used in the inkjet recording method is preferable.

  Hereinafter, each component constituting the recording medium of the present invention will be described.

<Base material>
As a base material, what is comprised only from a base paper, and the thing which has a base paper and a resin layer, ie, the thing by which the base paper is coat | covered with resin, are mentioned. In the present invention, it is preferable to use a base material having a base paper and a resin layer. In that case, the resin layer may be provided only on one side of the base paper, but is preferably provided on both sides.

(Base paper)
The base paper is made by using wood pulp as a main raw material and adding synthetic pulp such as polypropylene or synthetic fiber such as nylon or polyester as necessary. Wood pulp includes hardwood bleached kraft pulp (LBKP), hardwood bleached sulfite pulp (LBSP), softwood bleached kraft pulp (NBKP), softwood bleached sulfite pulp (NBSP), hardwood bleached pulp (LDP), coniferous melted pulp (NDP) ), Hardwood unbleached kraft pulp (LUKP), softwood unbleached kraft pulp (NUKP), and the like. These can use 1 type (s) or 2 or more types as needed. Among wood pulp, it is preferable to use LBKP, NBSP, LBSP, NDP, and LDP having a large amount of short fiber components. The pulp is preferably a chemical pulp (sulfate pulp or sulfite pulp) with few impurities. Moreover, the pulp which performed the bleaching process and improved the whiteness is also preferable. In the paper base material, a sizing agent, a white pigment, a paper strength enhancer, a fluorescent brightening agent, a moisture retention agent, a dispersing agent, a softening agent, and the like may be appropriately added.

  In the present invention, the thickness of the base paper is preferably 50 μm or more and 130 μm or less, and more preferably 90 μm or more and 120 μm or less. In the present invention, the thickness of the base paper is calculated by the following method. First, a cross section of the recording medium is cut out with a microtome, and the cross section is observed with a scanning electron microscope. And the film thickness of arbitrary 100 or more points of the base paper is measured, and the average value is defined as the film thickness of the base paper. The film thicknesses of the other layers in the present invention are calculated by the same method.

In the present invention, the paper density defined by JIS P 8118 of the base paper is preferably 0.6 g / cm ³ or more and 1.2 g / cm ³ or less. Further, it is more preferably 0.7 g / cm ³ or more and 1.2 g / cm ³ or less.

(Resin layer)
In the present invention, when the base paper is coated with a resin, the resin layer may be provided so as to cover a part of the surface of the base paper. The area of the surface of the base paper / the total area of the surface of the base paper) is preferably 70% or more, more preferably 90% or more, and further 100%, that is, It is particularly preferable that the entire surface is covered with a resin layer.

  In the present invention, the thickness of the resin layer is preferably 20 μm or more and 60 μm or less, and the thickness of the resin layer is more preferably 35 μm or more and 50 μm or less. When the resin layers are provided on both sides of the base paper, it is preferable that the film thicknesses of the resin layers on both sides satisfy the above ranges.

  The resin used for the resin layer is preferably a thermoplastic resin. Examples of the thermoplastic resin include an acrylic resin, an acrylic silicone resin, a polyolefin resin, and a styrene-butadiene copolymer. Among these, it is preferable to use a polyolefin resin. In the present invention, the polyolefin resin means a polymer using olefin as a monomer. Specifically, homopolymers and copolymers such as ethylene, propylene, and isobutylene are exemplified. The polyolefin resin can use 1 type (s) or 2 or more types as needed. Among these, it is preferable to use polyethylene. As the polyethylene, it is preferable to use low density polyethylene (LDPE) or high density polyethylene (HDPE).

In the present invention, the resin layer may contain a white pigment, a fluorescent whitening agent, ultramarine blue, and the like in order to adjust opacity, whiteness, and hue. Among them, it is preferable to contain a white pigment because opacity can be improved. Examples of the white pigment include rutile type or anatase type titanium oxide. In the present invention, the content of the white pigment in the resin layer is preferably 3 g / m ² or more and 30 g / m ² or less. In addition, when providing a resin layer on both surfaces of a base paper, it is preferable that content of the sum total of the white pigment in two resin layers satisfies the said range. Moreover, it is preferable that content of the white pigment in a resin layer is 25 mass% or less with respect to content of resin. If it is larger than 25% by mass, the dispersion stability of the white pigment may not be sufficiently obtained.

<Ink receiving layer>
In the present invention, the ink receiving layer may be a single layer or a multilayer of two or more layers. Further, the ink receiving layer may be provided only on one side of the base material or on both sides. The film thickness of the ink receiving layer on one side of the substrate is preferably 15 μm or more and 60 μm or less, and more preferably 30 μm or more and 45 μm or less. Hereinafter, materials that can be contained in the ink receiving layer will be described.

(Inorganic particles)
In the present invention, the ink receiving layer contains inorganic particles. The average primary particle diameter of the inorganic particles is preferably 50 nm or less. Furthermore, 1 nm or more and 30 nm or less are more preferable, and 3 nm or more and 10 nm or less are particularly preferable. In the present invention, the average primary particle diameter of the inorganic particles is the number average particle diameter of the diameter of a circle having an area equal to the projected area of the primary particles of the inorganic particles when observed with an electron microscope. At this time, at least 100 points are measured.

  In the present invention, the inorganic particles are preferably used in a coating solution for an ink receiving layer in a state where they are dispersed by a dispersant. The average secondary particle diameter of the inorganic particles in the dispersed state is preferably from 0.1 nm to 500 nm, more preferably from 1.0 nm to 300 nm, and particularly preferably from 10 nm to 250 nm. In addition, the average secondary particle diameter of the inorganic particles in the dispersed state can be measured by a dynamic light scattering method.

  In the present invention, the content (% by mass) of the inorganic particles in the ink receiving layer is preferably 50% by mass to 98% by mass, and more preferably 70% by mass to 96% by mass. Is more preferable.

In the present invention, the coating amount (g / m ² ) of inorganic particles applied when forming the ink receiving layer is preferably 8 g / m ² or more and 45 g / m ² or less. By setting it within the above range, it is easy to obtain a preferable ink receiving layer thickness.

  Examples of the inorganic particles used in the present invention include alumina hydrate, alumina, silica, colloidal silica, titanium dioxide, zeolite, kaolin, talc, hydrotalcite, zinc oxide, zinc hydroxide, aluminum silicate, calcium silicate, and silicic acid. Examples thereof include magnesium, zirconium oxide, and zirconium hydroxide. These inorganic particles can be used alone or in combination of two or more as required. Among the inorganic particles, it is preferable to use alumina hydrate, alumina, or silica that can form a porous structure with high ink absorbability.

The alumina hydrate used in the ink receiving layer is
Formula _{(X): Al 2 O 3} -n (OH) 2n · mH 2 O
(In general formula (X), n is 0, 1, 2, or 3, m is 0 or more and 10 or less, preferably 0 or more and 5 or less. However, m and n are not 0 at the same time.)
What is represented by these can be used suitably. In many cases, mH ₂ O represents a detachable aqueous phase that does not participate in the formation of a crystal lattice, and therefore m may not be an integer. Also, m can be zero when the alumina hydrate is heated.

  In the present invention, the alumina hydrate can be produced by a known method. Specifically, a method of hydrolyzing aluminum alkoxide, a method of hydrolyzing sodium aluminate, a method of adding an aqueous solution of aluminum sulfate or aluminum chloride to an aqueous solution of sodium aluminate and neutralizing, and the like can be mentioned.

  As the crystal structure of alumina hydrate, amorphous, gibbsite type, and boehmite type are known depending on the heat treatment temperature. The crystal structure of alumina hydrate can be analyzed by an X-ray diffraction method. Of these, boehmite type alumina hydrate or amorphous alumina hydrate is preferable in the present invention. Specific examples include alumina hydrates described in JP-A-7-232473, JP-A-8-132731, JP-A-9-66664, JP-A-9-76628, and the like, as commercially available products. Includes Dispersal HP14 and HP18 (above, manufactured by Sasol). These alumina hydrates can be used alone or in combination of two or more as required.

In the present invention, the specific surface area of the alumina hydrate determined by the BET method is preferably 100 m ² / g or more and 200 m ² / g or less, more preferably 125 m ² / g or more and 175 m ² / g or less. preferable. Here, the BET method is a method in which a specific surface area of a sample is measured from an adsorbed amount by adsorbing molecules and ions of a known size on the sample surface. In the present invention, nitrogen gas is used as the gas adsorbed on the sample.

  As the alumina used for the ink receiving layer, vapor phase alumina is preferable. Examples of the vapor phase method alumina include γ-alumina, α-alumina, δ-alumina, θ-alumina, and χ-alumina. Among these, it is preferable to use γ-alumina from the viewpoint of the optical density of the image and the ink absorbability. Specific examples of vapor-phase process alumina include AEROXIDE; Alu C, Alu 130, Alu 65 (above, EVONIK).

In the present invention, the specific surface area determined by the BET method of vapor phase alumina is preferably 50 m ² / g or more, more preferably 80 m ² / g or more. Moreover, 150 m < ² > / g or less is preferable and 120 m < ² > / g or less is more preferable.

  Further, the average primary particle diameter of vapor-phase process alumina is preferably 5 nm or more, and more preferably 11 nm or more. Moreover, 30 nm or less is preferable and 15 nm or less is more preferable.

The alumina hydrate and alumina used in the present invention are preferably mixed in the ink receiving layer coating solution as an aqueous dispersion, and an acid is preferably used as the dispersant. As an acid,
Formula _{(Y): R-SO 3} H
(In general formula (Y), R represents any one of a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, and an alkenyl group having 1 to 4 carbon atoms. R represents an oxo group, a halogen atom, an alkoxy group, And may be substituted with an acyl group.)
It is preferable to use a sulfonic acid represented by the formula because an effect of suppressing image bleeding is obtained. In the present invention, the content of the acid is preferably 1.0% by mass or more and 2.0% by mass or less, based on the total content of alumina hydrate and alumina, and 1.3% by mass. More preferably, it is 1.6 mass% or less.

  Silica used in the ink receiving layer is roughly classified into a wet method and a dry method (gas phase method) depending on the production method. As a wet method, there is known a method in which active silica is produced by acid decomposition of silicate, and this is appropriately polymerized and coagulated and precipitated to obtain hydrous silica. On the other hand, as a dry method (gas phase method), a method using high-temperature gas phase hydrolysis of silicon halide (flame hydrolysis method) or silica sand and coke are heated and reduced and vaporized by an arc in an electric furnace. A method is known in which anhydrous silica is obtained by a method of oxidizing carbon with air (arc method). In the present invention, it is preferable to use silica obtained by a dry method (gas phase method) (hereinafter also referred to as “gas phase method silica”). This is because vapor-phase process silica has a particularly large specific surface area, and therefore has a particularly high ink absorbency and a low refractive index, so that transparency can be imparted to the ink-receiving layer and good color developability can be obtained. It is. Specifically, examples of the vapor phase method silica include Aerosil (manufactured by Nippon Aerosil), Leolosil QS type (manufactured by Tokuyama), and the like.

In the present invention, the specific surface area of the vapor phase silica by the BET method is preferably 50 m ² / g or more and 400 m ² / g or less, and more preferably 200 m ² / g or more and 350 m ² / g or less.

  In the present invention, the vapor phase silica is preferably used in the coating liquid for the ink receiving layer in a state where it is dispersed by a dispersant. The particle diameter of the vapor phase method silica in the dispersed state is more preferably from 50 nm to 300 nm. The particle diameter of the vapor phase silica in the dispersed state can be measured by a dynamic light scattering method.

  In the present invention, alumina hydrate, alumina and silica may be mixed and used. Specifically, a method of mixing and dispersing at least two kinds selected from alumina hydrate, alumina, and silica in a powder state to obtain a dispersion liquid can be mentioned. In the present invention, it is preferable to use both alumina hydrate and vapor phase alumina as inorganic particles. In that case, the content (mass%) of alumina hydrate contained in the outermost surface layer of the ink receiving layer is 60/40 times or more by mass ratio with respect to the content (mass%) of vapor phase method alumina. It is preferably 90/10 times or less, that is, 1.5 times or more and 9.0 times or less.

(binder)
In the present invention, the ink receiving layer contains a binder. In the present invention, the binder means a material that can bind inorganic particles and form a film.

  In the present invention, from the viewpoint of ink absorptivity, the content of the binder in the ink receiving layer is preferably 50% by mass or less and more preferably 30% by mass or less with respect to the content of the inorganic particles. Further, from the viewpoint of the binding property of the ink receiving layer, the ratio is preferably 5.0% by mass or more, and more preferably 8.0% by mass or more.

  Examples of the binder include starch derivatives such as oxidized starch, etherified starch, and phosphate esterified starch; cellulose derivatives such as carboxymethyl cellulose and hydroxyethyl cellulose; casein, gelatin, soybean protein, polyvinyl alcohol, and derivatives thereof; polyvinyl Conjugated polymer latex such as pyrrolidone, maleic anhydride resin, styrene-butadiene copolymer, methyl methacrylate-butadiene copolymer; acrylic polymer latex such as acrylate ester and methacrylate ester polymer; ethylene-vinyl acetate A vinyl polymer latex such as a copolymer; a functional group-modified polymer latex with a functional group-containing monomer such as a carboxyl group of the polymer; a polymer obtained by cationizing the polymer using a cationic group; A cationized surface of the polymer using a thionic surfactant; a monomer that forms the polymer under cationic polyvinyl alcohol, and a polyvinyl alcohol distributed on the surface of the polymer; a cation Polymers in which the monomer constituting the polymer is polymerized in a suspension dispersion of the conductive colloidal particles and the cationic colloidal particles are distributed on the surface of the polymer; aqueous such as thermosetting synthetic resins such as melamine resin and urea resin Binders; Polymers and copolymers of acrylic acid esters and methacrylic acid esters such as polymethyl methacrylate; polyurethane resins, unsaturated polyester resins, vinyl chloride-vinyl acetate copolymers, polyvinyl butyral, alkyd resins and the like It is done. These binders can use 1 type (s) or 2 or more types as needed.

  Among the binders described above, it is preferable to use polyvinyl alcohol or polyvinyl alcohol derivatives. Examples of the polyvinyl alcohol derivative include cation-modified polyvinyl alcohol, anion-modified polyvinyl alcohol, silanol-modified polyvinyl alcohol, and polyvinyl acetal. Examples of the cation-modified polyvinyl alcohol include a 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, for example, JP-A-61-110483. Alcohol is preferred.

  Polyvinyl alcohol can be synthesized, for example, by saponifying polyvinyl acetate. The saponification degree of polyvinyl alcohol is preferably 80 mol% or more and 100 mol% or less, and more preferably 85 mol% or more and 98 mol% or less. The degree of saponification is the ratio of the number of moles of hydroxyl groups produced by the saponification reaction when polyvinyl alcohol is obtained by saponifying polyvinyl acetate. In the present invention, the value measured by the method of JIS-K6726. Shall be used. The average degree of polymerization of polyvinyl alcohol is preferably 2,000 or more, and more preferably 2,000 or more and 5,000 or less. In the present invention, the average degree of polymerization is the viscosity average degree of polymerization determined by the method of JIS-K6726.

  When preparing a coating liquid for an ink receiving layer, it is preferable to use polyvinyl alcohol or a polyvinyl alcohol derivative as an aqueous solution. In that case, the solid content of the polyvinyl alcohol and the polyvinyl alcohol derivative in the aqueous solution is preferably 3% by mass or more and 20% by mass or less.

(Crosslinking agent)
In the present invention, the ink receiving layer preferably further contains a crosslinking agent. Examples of the crosslinking agent include aldehyde compounds, melamine compounds, isocyanate compounds, zirconium compounds, amide compounds, aluminum compounds, boric acid, and borate. These crosslinking agents can be used alone or in combination of two or more as required. In particular, when polyvinyl alcohol or a polyvinyl alcohol derivative is used as a binder, it is preferable to use boric acid or a borate among the above-described crosslinking agents.

Examples of boric acid include orthoboric acid (H ₃ BO ₃ ), metaboric acid, and diboric acid. As the borate, the water-soluble salt of boric acid is preferable. Examples thereof include alkali metal salts of boric acid such as sodium salt and potassium salt of boric acid; alkaline earth metal salts of boric acid such as magnesium salt and calcium salt of boric acid; ammonium salt of boric acid and the like. Among these, it is preferable to use orthoboric acid from the viewpoint of the temporal stability of the coating liquid and the effect of suppressing the occurrence of cracks.

  The amount of the crosslinking agent used can be appropriately adjusted according to the production conditions. In the present invention, the content of the crosslinking agent in the ink receiving layer is preferably 1.0% by mass or more and 50% by mass or less, and more preferably 5% by mass or more and 40% by mass or less with respect to the content of the binder. .

  Furthermore, when the binder is polyvinyl alcohol and the crosslinking agent is at least one selected from boric acid and borate, boric acid and borate with respect to the content of polyvinyl alcohol in the ink receiving layer The total content is preferably 5% by mass or more and 30% by mass or less.

(Other additives)
In the present invention, the ink receiving layer may contain other additives other than those described above. Specifically, pH adjusters, thickeners, fluidity improvers, antifoaming agents, antifoaming agents, surfactants, mold release agents, penetrating agents, coloring pigments, colored dyes, fluorescent whitening agents, UV absorption Agents, antioxidants, antiseptics, antifungal agents, water resistance agents, dye fixing agents, curing agents, weathering materials and the like.

  Particularly in the present invention, the ink receiving layer comprises a sulfur-containing organic compound (A) having two or more active hydrogen groups, a polyisocyanate compound (B) having two or more isocyanate groups, and two or more active hydrogen groups. A polymer compound in which at least part of the amino group in the resulting product is further cationized with an acid (hereinafter also simply referred to as “polymer compound”). ) Is preferably contained. A specific example of the polymer compound is preferably at least one compound selected from the group consisting of the following general formulas (1) to (6). By containing such a polymer compound, nitration and oxidation of BHT can be suppressed when BHT or the like adheres.

(In General Formula (1), n represents 1 or 2, R ₁ represents a methylene group, an ethylene group, or a propylene group. R ₉ represents an aliphatic group that includes one or more alkylene groups or double alicyclic rings (alicyclic structures). A hydrocarbon group, R ₁₀ is an alkyl group having 1 to 4 carbon atoms, R ₁₁ and R ₁₂ are each independently a hydrogen atom or a methyl group, and X ⁻ represents an acid anion.)

(In general formula (2), n is 1 or 2, R ₂ and R ₃ each independently represent a hydrogen atom, a hydroxyl group or an alkyl group, and R ₂ and R ₃ may be the same or different. R ₉ is an alkylene group or an aliphatic hydrocarbon group containing at least one double alicyclic ring (alicyclic structure), R ₁₀ is an alkyl group having 1 to 4 carbon atoms, R ₁₁ and R ₁₂ are each independently a hydrogen atom or methyl group, X ^- represents an anion).

(In general formula (3), n is 0 or 1, R ₉ is an alkylene group or an aliphatic hydrocarbon group containing one or more double alicyclic rings (alicyclic structures), and R ₁₀ is an alkyl group having 1 to 4 carbon atoms. , R ₁₁ and R ₁₂ are each independently a hydrogen atom or a methyl group, and X ⁻ represents an acid anion.)

(In General Formula (4), n represents 1 or 2, R ₄ represents a sulfur atom or an oxygen atom, R ₅ represents a sulfur atom or —SO ₂ —, and R ₄ and R ₅ are not the same, and each represents a different group. R ₉ is an alkylene group or an aliphatic hydrocarbon group containing at least one double alicyclic ring (alicyclic structure), R ₁₀ is an alkyl group having 1 to 4 carbon atoms, and R ₁₁ and R ₁₂ are each independently A hydrogen atom or a methyl group, and X ⁻ represents an acid anion.)

(In General Formula (5), R ₆ and R ₇ each independently represent a hydrogen atom or an alkyl group, and R ₆ and R ₇ may be the same or different. R ₉ is an alkylene group or a double fat. An aliphatic hydrocarbon group containing at least one ring (alicyclic structure), R ₁₀ is an alkyl group having 1 to 4 carbon atoms, R ₁₁ and R ₁₂ are each independently a hydrogen atom or a methyl group, and X ⁻ is an acid anion Represents.)

(In General Formula (6), R ₈ represents a hydroxyl group or an alkyl group. R ₉ represents an aliphatic hydrocarbon group containing one or more alkylene groups or double alicyclic rings (alicyclic structures), and R ₁₀ represents 1 to 1 carbon atoms. 4 alkyl groups, R ₁₁ and R ₁₂ are each independently a hydrogen atom or a methyl group, and X ⁻ represents an acid anion).

  The sulfur-containing organic compound (A) (hereinafter also simply referred to as “compound A”) used for the synthesis of the polymer compound is not particularly limited, but a compound having at least one sulfide group in the molecule is preferable. Specific examples include at least one compound selected from the group consisting of the following general formulas (7) to (12). In particular, the compound represented by the general formula (8) or the general formula (12) has a high effect of suppressing discoloration of an image due to acidic gas or light in the atmosphere, and can be preferably used. The following sulfur-containing organic compounds (A) can be used alone or in combination of two or more thereof to synthesize the polymer compound of the present invention.

(In general formula (7), n represents 1 or 2, and R ₁ represents a methylene group, an ethylene group, or a propylene group.)

(In General Formula (8), n is 1 or 2, R ₂ and R ₃ each independently represent a hydrogen atom, a hydroxyl group or an alkyl group, and R ₂ and R ₃ may be the same or different. )

(In general formula (9), n represents 0 or 1)

(In the general formula (10), n represents 1 or 2, R ₄ represents a sulfur atom or an oxygen atom, R ₅ represents a sulfur atom or —SO ₂ —, and R ₄ and R ₅ are not the same, and each represents a different group. Composed.)

(In general formula (11), R ₆ and R ₇ each independently represent a hydrogen atom or an alkyl group, and R ₆ and R ₇ may be the same or different.)

(In the general formula (12), R ₈ represents a hydroxyl group or an alkyl group).

Examples of the polyisocyanate compound (B) (hereinafter also simply referred to as “compound B”) used for the synthesis of the polymer compound include, but are not limited to, the following compounds.
2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, m-phenylene diisocyanate, p-phenylene diisocyanate.
4,4'-diphenylmethane diisocyanate, 2,4'-diphenylmethane diisocyanate, 2,2'-diphenylmethane diisocyanate, 3,3'-dimethyl-4,4'-biphenylene diisocyanate.
3,3'-dichloro-4,4'-biphenylene diisocyanate, 1,5-naphthalene diisocyanate, 1,5-tetrahydronaphthalene diisocyanate, tetramethylene diisocyanate.
1,6-hexamethylene diisocyanate, dodecamethylene diisocyanate, trimethylhexamethylene diisocyanate, 1,3-cyclohexylene diisocyanate, 1,4-cyclohexylene diisocyanate.
Xylylene diisocyanate, tetramethyl xylylene diisocyanate, hydrogenated xylylene diisocyanate, lysine diisocyanate, isophorone diisocyanate, 4,4'-dicyclohexylmethane diisocyanate.

  Moreover, it is possible to synthesize a polymer compound using these polyisocyanate compounds alone or in combination of two or more.

  As the amine compound (C) (hereinafter also simply referred to as “compound C”) used for the synthesis of the polymer compound, for example, a tertiary amine represented by the following general formula (13) is preferable.

(In General Formula (13), any one of R ₁ , R ₂ , and R ₃ is an alkyl group having 1 to 6 carbon atoms, an alkanol group, or an aminoalkyl group. Often represents an alkanol group, an aminoalkyl group, or an alkanethiol group).

  Specific examples of the compound represented by the general formula (13) include, for example, diol compounds such as N-methyl-N, N-diethanolamine, N-ethyl-N, N-diethanolamine, N-isobutyl-N, N-diethanolamine, Nt-butyl-N, N-diethanolamine, Nt-butyl-N, N-diisopropanolamine and the like, and examples of the triol compound include triethanolamine. Examples of the diamine compound include methyliminobispropylamine and butyliminobispropylamine, and examples of the triamine compound include tri (2-aminoethyl) amine. These amine compounds can be used alone or in combination of two or more to synthesize a polymer compound.

  The polymer compound reacts compound A, compound B, and compound C as described above, and compound A unit, compound B unit, and compound C unit (the tertiary amine in the unit is cationized) in the molecule. Obtained as a polymer. The content of Compound C in the polymer compound is preferably 5.5% or more and 18.5% or less in terms of molar ratio. When the content of Compound C is lower than 5.5% in terms of molar ratio, the content of hydrophilic groups is lowered, which is inconvenient when preparing an aqueous dispersion of a polymer compound, or forms an ink receiving layer. In some cases, it may be difficult to mix the aqueous coating liquid. On the other hand, when the content of Compound C is higher than 18.5% in terms of molar ratio, glossiness and print density may be lowered in an ink jet recording medium containing the polymer compound.

  If the molar ratio of the compound C in the polymer compound is within the above range, the compound C unit can occupy 3% by mass or more and 80% by mass or less in the polymer compound. Exceeding this range may cause a decrease in the function of the polymer compound as described above.

  In the polymer compound, if the content of compound C is in the above range, the mass of the incorporated compound A unit preferably occupies 10 to 65% by mass in the polymer. More preferably, it is the ratio which occupies 30-65 mass%. When the proportion of the compound A unit is less than 10% by mass, the effect as a polymer compound may be insufficient. On the other hand, when the proportion of the compound A unit exceeds 65% by mass, the content of the hydrophilic group is relatively lowered, which may be inconvenient when adjusting the aqueous dispersion of the polymer compound.

  Compound B has a function of linking compound A and compound C, and the amount of compound B used is not particularly limited. However, if the content of compound C is in the above range, the mass of compound B unit is obtained. It is preferable to occupy 10 to 80% by mass in the polymer. More preferably, it is the ratio which occupies 30-60 mass%. When the proportion of the compound B unit is within this range, an amount sufficient to sufficiently exert the functions of the unit of compound A and compound C can be combined.

  In addition, the method for synthesizing the polymer compound using the compounds A to C may be a one-shot method or a prepolymer method. In the one-shot method, the compounds A to C are reacted at once to form a random polymer. In the prepolymer method, compound A (or compound C) and compound B are reacted in a ratio rich in isocyanate groups to synthesize a prepolymer having a terminal isocyanate group, and the prepolymer and compound C (or compound A) React. In any method, a chain extender such as a low molecular weight polyol or a low molecular weight diamine may be used in combination. In addition, the molecular weight of the resulting polymer compound can be adjusted by changing the amount of compounds A to C used or adding a reaction terminator such as monoalcohol or monoamine to the reaction system at an appropriate timing.

  The weight average molecular weight of the polymer compound thus obtained depends on the reaction conditions, but is preferably in the range of 2,000 to 150,000, and more preferably in the range of 2,000 to 50,000. If the weight average molecular weight of the polymer compound is less than 2,000, the glossiness and the print density may decrease. If it exceeds 150,000, the reaction time becomes longer and the synthesis cost increases, which is not preferable.

  In the synthesis of the polymer compound, a compound having two or more active hydrogen groups (hereinafter referred to as “compound D”) other than the compound A and the compound C may be copolymerized as necessary. As such compound D, the following polyester polyols, polyether polyols, or polycarbonate polyols may be used alone or in combination of two or more.

  Examples of the polyester polyol include ethylene glycol, propylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 3-methyl-1,5-pentanediol, and 1,6-hexane. Diol, neopentyl glycol diol, diethylene glycol, triethylene glycol, tetraethylene glycol, polyethylene glycol having a molecular weight of 300 to 1000, dipropylene glycol, tripropylene glycol, bishydroxyethoxybenzene, 1,4-cyclohexanedimethanol, bisphenol A , Glycol components such as bisphenol S, hydrogenated bisphenol A, hydroquinone, alkylene oxide adduct, malonic acid, succinic acid, glutaric acid, adipic acid Pimelic acid, suberic acid, azelaic acid, sebacic acid, hedecane dicarboxylic acid, decanedicarboxylic acid, dodecanedicarboxylic acid, maleic anhydride, fumaric acid, 1,3-cyclopentanedicarboxylic acid, terephthalic acid, isophthalic acid, phthalic acid, 1,4-naphthalenedicarboxylic acid, 2,5-naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, naphthalic acid, biphenyldicarboxylic acid, 1,2-bisphenoxyethane-p, p'-dicarboxylic acid, dicarboxylic acid Polyesters obtained by ring-opening polymerization reaction of cyclic ester compounds such as ε-caprolactone, including polyesters obtained by dehydration condensation reaction from acid components such as anhydrides or ester-forming derivatives, or the like Examples of copolyesters It is done.

  Examples of the polyether polyol include ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, trimethylene glycol, 1,3-butanediol, 1,4-butanediol, 1,5-pentanediol, and 1,6-hexane. Diol, neopentyl glycol, glycerin, trimethylol ethane, trimethylol propane, sorbitol, sucrose, bisphenol A, bisphenol S, hydrogenated bisphenol A, aconitic acid, trimellitic acid, hemimellitic acid, phosphoric acid, ethylenediamine, diethylenetriamine, triisopropanol Compound having at least two active hydrogens such as amine, pyrogallol, dihydroxybenzoic acid, hydroxyphthalic acid, 1,2,3-propanetrithiol The product obtained by subjecting a product to addition polymerization by a conventional method using one or more monomers such as ethylene oxide, propylene oxide, butylene oxide, styrene oxide, epichlorohydrin, tetrahydrofuran, and cyclohexylene as an initiator. It is done. In addition, as a polyol, an ethylene oxide, propylene oxide, butylene oxide, styrene oxide, epichlorohydrin, tetrahydrofuran, cyclohexylene, etc., using a compound having at least two primary amino groups such as ethylenediamine and propylenediamine as an initiator. It is also possible to use those obtained by addition polymerization of one or more of these monomers by a conventional method. Particularly preferred is polyethylene glycol.

  Examples of the polycarbonate polyol include compounds obtained by reacting glycols such as 1,4-butanediol, 1,6-hexanediol, diethylene glycol and the like with diphenyl carbonate and phosgene.

  The polymer compound preferably uses a tin-based catalyst and / or an amine-based catalyst in the isocyanate polyaddition reaction. Examples of the tin-based catalyst include dibutyltin dilaurate and stannous octoate. Examples of the amine catalyst include, but are not limited to, triethylenediamine, triethylamine, tetramethylpropanediamine, tetramethylbutanediamine, and N-methylmorpholine.

  The isocyanate polyaddition reaction can be carried out in the absence of a solvent depending on the composition. However, a hydrophilic organic solvent that is not directly involved in the isocyanate polyaddition reaction system is generally used as a reaction solvent for the purpose of suppressing reaction in the reaction system or controlling the base viscosity. Examples of such hydrophilic organic solvents include ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, and diisobutyl ketone; methyl formate, ethyl formate, propyl formate, butyl formate, methyl acetate, ethyl acetate, propyl acetate, butyl acetate And organic acid esters such as methyl propionate, ethyl propionate and butyl propionate; and amines such as N, N-dimethylformamide and N-methylpyrrolidone. Moreover, it is preferable that the used hydrophilic organic solvent is finally removed.

  The polymer compound can be dispersed and stabilized or dissolved in water by cationizing at least a part of the compound C unit with an acid. Alternatively, when cationized with a quaternizing agent such as an alkyl halide, it cannot be stabilized or dissolved in water at a preferred particle size. The acid used here is not particularly limited, but when a polyvalent acid is used, it may cause thickening when the polymer compound is dispersed or dissolved in water. Are preferred. Examples of phosphoric acid include phosphoric acid and phosphorous acid. Examples of the monovalent acid include organic acids such as formic acid, acetic acid, propionic acid, butyric acid, glycolic acid, lactic acid, pyruvic acid, and methanesulfonic acid, and inorganic acids such as hydrochloric acid and nitric acid. These acids become acid anions by cationizing the compound C unit. In addition, when the polymer compound cationized with a hydroxy acid is applied to the formation of an ink receiving layer of an ink jet recording medium, the non-printing portion is compared with the case of using a polymer compound cationized with another acid. Yellowing of (blank paper portion) is suppressed. For this reason, more preferably, a polymer compound cationized with a hydroxy acid can be used.

  When the polymer compound is dispersed in an aqueous medium, the average particle size of the dispersion is preferably in the range of 5 nm to 500 nm from the viewpoint of storage stability. In order to improve ink absorptivity when it becomes an ink jet recording medium, it is preferably larger than 50 nm and not larger than 200 nm. Moreover, the average particle diameter as used in the field of this invention is measured by the dynamic light scattering method. For example, it can be easily measured using a nano track (UPA-150EX, manufactured by Nikkiso Co., Ltd.).

  The polymer compound preferably has a glass transition temperature (Tg) of 50 ° C. or higher and 80 ° C. or lower. The glass transition temperature can be easily measured by DSC. When Tg is lower than 50 ° C., the film is increased before drying or immediately after drying, so that the above-mentioned pores are not formed, and the effect of improving ink absorbency may be small. When the Tg is higher than 80 ° C., the particle property remains even after the drying step, and it may be difficult to obtain a transparent film.

  The content of the polymer compound in the ink receiving layer is preferably 0.5 parts by mass or more and 8 parts by mass or less, more preferably 2% by mass or more and 4% by mass or less with respect to 100 parts by mass of the inorganic particles. preferable.

[Method of manufacturing recording medium]
In the present invention, the method for producing a recording medium is not particularly limited, but the recording medium includes a step of preparing a coating liquid for the ink receiving layer and a step of coating the base material with the coating liquid for the ink receiving layer. A method for producing the medium is preferred. Hereinafter, a method for manufacturing the recording medium will be described.

<Method for producing substrate>
In the present invention, a generally used paper making method can be applied as a method for producing the base paper. Examples of the paper machine include a long net paper machine, a round net paper machine, a cylinder, and a twin wire. In order to improve the surface smoothness of the base paper, surface treatment may be performed by applying heat and pressure during the paper making process or after the paper making process. Specific surface treatment methods include calendar processing such as machine calendar and super calendar.

  Examples of a method of providing a resin layer on the base paper, that is, a method of coating the base paper with a resin include a melt extrusion method, wet lamination, dry lamination, and the like. Among these, a melt extrusion method in which a molten resin is applied to one side or both sides of a base paper by extrusion coating is preferable. For example, a method of laminating a resin layer on a base paper by bringing the conveyed base paper into contact with the resin extruded from an extrusion die at a nip point between a nip roller and a cooling roller and press-bonding at the nip (extrusion) (Also called coating method) is widely adopted. When the resin layer is provided by melt extrusion, pretreatment may be performed so that the adhesion between the base paper and the resin layer becomes stronger. Examples of the pretreatment include an acid etching treatment using a mixed solution of chromic sulfate, a flame treatment using a gas flame, an ultraviolet irradiation treatment, a corona discharge treatment, a glow discharge treatment, and an anchor coat treatment such as an alkyl titanate. Among these, corona discharge treatment is preferable. Further, when the resin layer contains a white pigment, the base paper may be covered with a mixture of resin and white pigment.

<Method for forming ink receiving layer>
In the recording medium of the present invention, examples of the method for forming the ink receiving layer on the substrate include the following methods. First, an ink receiving layer coating solution is prepared. And the recording medium of this invention can be obtained by apply | coating and drying the said coating liquid on a base material. As a coating method of the coating liquid, a curtain coater, a coater using an extrusion method, a coater using a slide hopper method, or the like can be used. In addition, you may heat a coating liquid at the time of coating. In addition, as a drying method after coating, a method using a hot air dryer such as a straight tunnel dryer, an arch dryer, an air loop dryer, a sine curve air float dryer, an infrared ray, a heated dryer, a microwave, or the like was used. Examples include a method using a dryer.

[Recording medium packaging]
The recording medium package of the present invention has a base material, an ink receiving layer containing inorganic particles and a binder, and an oxygen permeability of 15.0 cc · 20 μm / m ² · day · atom or less. Packaging material.

  Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples. The present invention is not limited in any way by the following examples as long as the gist thereof is not exceeded. In the description of the following examples, “part” is based on mass unless otherwise specified.

[Production of recording medium]
<Preparation of base material>
Canada Standard Freeness 450 mLCSF LBKP 80 parts, Canada Standard Freeness 480 mLCSF NBKP 20 parts, Cationic Starch 0.60 parts, Heavy Calcium Carbonate 10 parts, Light Calcium Carbonate 15 parts, Alkylketene Dimer 0.10 parts Then, 0.030 parts of cationic polyacrylamide was mixed, and water was added so that the solid content was 3.0% by mass to obtain a paper stock. Next, the stock was made with a long paper machine, subjected to a three-stage wet press, and then dried with a multi-cylinder dryer. Thereafter, the starch starch aqueous solution was impregnated and dried so that the solid content after drying with a size press machine was 1.0 g / m ^2, and further machine calendered to a basis weight of 170 g / m ² . A base paper having a sizing degree of 100 seconds, an air permeability of 50 seconds, a Beck smoothness of 30 seconds, a Gurley stiffness of 11.0 mN, and a film thickness of 100 μm was prepared. Next, a resin composition consisting of 70 parts of low density polyethylene, 20 parts of high density polyethylene and 10 parts of titanium oxide was applied to one side of the base paper so that the dry coating amount was 25 g / m ² . . This surface is the surface of the substrate. Furthermore, the base material was obtained by coating low-density polyethylene on the other surface of the base paper so that the dry coating amount was 25 g / m ² .

<Preparation of coating solution for ink receiving layer>
(Preparation of coating solution 1)
After adding 1.88 g of methanesulfonic acid to 372.80 g of pure water and stirring for 5 minutes using a mixer, 125.00 g of alumina hydrate DISPERAL HP14 (manufactured by Sasol) is added and stirred for 30 minutes. In addition, the alumina hydrate dispersion was adjusted so that the solid content concentration of alumina hydrate was 22.0% by mass.

  Separately, a binder aqueous solution having a solid content of 9.0% by mass was prepared using PVA235 (manufactured by Kuraray), which is a polyvinyl alcohol having a polymerization degree of 3,500 and a saponification degree of 88 mol% as a binder aqueous solution.

  Furthermore, as the crosslinking agent aqueous solution of the binder, boric acid was used to prepare a crosslinking agent aqueous solution having a solid content of 5.0% by mass.

  The alumina hydrate dispersion and the aqueous crosslinking agent solution are mixed with 100 parts of the solid content of the alumina hydrate so as to have a solid content of 1 part of the aqueous solution of the crosslinking agent. A coating solution 1 was prepared by mixing 10 parts with respect to 100 parts of the solid content of the Japanese product.

(Adjustment of coating solution 2)
Disperse 100.00 g of silica (trade name: A300, manufactured by Nippon Aerosil) and 4.00 g of cationic polymer (trade name: Charol DC902P, manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) in ion-exchanged water so that the solid content concentration is 18% And dispersed with a high-pressure homogenizer to obtain a silica dispersion.

  The silica dispersion and the aqueous crosslinking agent solution are mixed with 100 parts of silica solids so that the solid content of the crosslinking agent aqueous solution is 2.5 parts, and then the organic binder aqueous solution is mixed with the solid solution of alumina hydrate. It mixed so that it might become 25 parts with respect to 100 parts per minute, and the coating liquid 2 was adjusted.

(Adjustment of coating solution 3)
A polymer compound was synthesized as follows. A reaction vessel equipped with a stirrer, a thermometer, and a reflux condenser is charged with 140 g of acetone as a reaction solvent, and, with stirring, 50.00 g of 3,6-dithia-1,8-octanediol and 10.46 g of methyldiethanolamine. Dissolved. Thereafter, the temperature was raised to 40 ° C. and 79.66 g of isophorone diisocyanate was added. Thereafter, the temperature was raised to 50 ° C., 0.4 g of a tin-based catalyst was added, the temperature was further raised to 55 ° C., and the reaction was carried out for 4 hours while stirring.

  After completion of the reaction, the reaction solution was cooled to room temperature and cationized by adding 9.14 g of 35% hydrochloric acid. Further, 573 g of water was added, concentrated under reduced pressure to remove acetone, and further adjusted with water to prepare an aqueous dispersion of polymer compound 1 of the present invention having a solid content of 20% (polymer compound 1- 1) was synthesized. When an average particle size was measured with UPA-150EX in a 1% aqueous solution, it was 35 nm. Moreover, it was 60 degreeC when the glass transition temperature (Tg) was measured.

  Next, the aqueous dispersion of the coating liquid 1 and the polymer compound 1 is mixed and stirred so that the polymer compound 1 is 2 parts with respect to 100 parts of the alumina hydrate in the coating liquid 1 Liquid 3 was obtained.

<Preparation of recording medium for evaluation>
On the base material obtained above, the coating liquids 1 to 3 prepared above are applied so that the dry coating amount is 30 g / m ^2, and dried at 60 ° C. for 30 minutes to obtain a recording medium 1 3 was obtained. Further, the BHT acetone solution was applied to the recording media 1 to 3 so that the coating amount of BHT was 0.1 g / m ^2, and dried at 60 ° C. for 5 minutes. Obtained.

<Production of packaging materials>
A film having a multilayer structure was prepared by a coextrusion method using the materials and thickness materials described in Table 1 below. Subsequently, the obtained film was heat-sealed to produce a bag-shaped packaging material in which the first layer side was the outside. Table 1 also shows the oxygen permeability and water vapor permeability of each packaging material. Abbreviations in Table 1 are as follows.
CPP: unstretched polyethylene PAN: polyacrylonitrile LDPE: low-density polyethylene PET: polyethylene terephthalate HDPE: high-density polyethylene EP48: ethylene-vinyl alcohol copolymer (ethylene 48 mol%)
EP44: Ethylene-vinyl alcohol copolymer (ethylene 44 mol%)
EP32: Ethylene-vinyl alcohol copolymer (ethylene 32 mol%)

<Production of packaging>
A package was prepared using a combination of the recording medium for evaluation and the packaging material shown in Table 2 below. When producing a package, a recording medium was placed in the packaging material and sealed by heat sealing. At this time, the inner volume of the package was 1.83 times the volume of the packaged recording medium.

[Evaluation]
The package obtained above was stored for 2 weeks at a temperature of 50 ° C. The evaluation recording medium before and after storage was visually observed to evaluate the yellowing prevention effect of the recording medium. The evaluation criteria are as follows. The evaluation results are shown in Table 2.
AA: Yellowing was not visually recognized. A: Yellowing was slightly visually recognized. B: Yellowing was visually recognized, but the level was not noticeable. C: Yellowing was conspicuous.

Claims (7)

A packaging material for hermetically packaging a recording medium having a substrate and an ink receiving layer containing inorganic particles and a binder,
The packaging material, wherein the packaging material has an oxygen permeability of 15.0 cc · 20 μm / m ² · day · atom or less. The packaging material according to claim 1, wherein the packaging material has an oxygen permeability of 10.0 cc · 20 μm / m ² · day · atom or less. The packaging material according to claim 1, wherein the packaging material has an oxygen permeability of 5.0 cc · 20 μm / m ² · day · atom or less. The packaging material according to claim 1, wherein the packaging material has an oxygen permeability of 2.0 cc · 20 μm / m ² · day · atom or less. The packaging material according to any one of claims 1 to 4, wherein the packaging material has a water vapor permeability of 20 g / m ² · day or less. A recording medium package comprising a substrate, a recording medium having an ink receiving layer containing inorganic particles and a binder, and a packaging material for hermetically packaging the recording medium,
A recording medium packaging body, wherein the packaging material has an oxygen permeability of 15.0 cc · 20 μm / m ² · day · atom or less. The ink-receiving layer of the recording medium has a sulfur-containing organic compound (A) having two or more active hydrogen groups, a polyisocyanate compound (B) having two or more isocyanate groups, and two or more active hydrogens. The amine compound (C) having a group is reacted with at least three kinds of compounds, and the resulting product contains a polymer compound in which at least a part of the amino group is further cationized with an acid. Recording media package.