JP2001010214A - Ink jet recording paper - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ink jet recording paper of which the light-resistance and the indoor discoloration property are improved without unfavorably affecting the ink absorbing property. SOLUTION: For this recording paper, an ink absorbing layer containing at least an inorganic particle, a hydrophilic binder and a nitrogen-containing compound is provided on a non-water-absorbent supporting body. In this case, the peak area ratio (N1S/C1S) of a carbon atom 1S for which the cross section in the film thickness direction of the ink absorbing layer measured by an X-ray photoelectric spectrometry to a nitrogen atom 1S which has not become an ammonium salt, is 0.01 to 0.2. Also, the area ratio of a section which is approx. 1/3 from the surface of the overall film thickness is higher by 0.01 or more than the area ratio of a section other than that.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink jet recording sheet (hereinafter, also simply referred to as a recording sheet), and more particularly to an ink jet recording sheet having improved discoloration and light fastness due to oxygen and a method for producing the same.

[0002]

2. Description of the Related Art In recent years, the image quality of ink jet recording has been rapidly improved, and the quality of photographs is approaching. In order to achieve such photographic image quality by ink jet recording, improvements are also being made in the surface of recording paper, and recording paper provided with a fine gap layer on a highly smooth support has improved ink absorption and drying properties. Because of its excellence, it is becoming one of the closest to photographic quality.

[0003] With such high image quality, characteristics required for recording paper have been further enhanced. In particular, ink-jet recording paper in which a support is a non-water-absorbing support and an ink-absorbing layer is provided thereon is used for ink-jet recording. Since the support maintains high smoothness during recording, a high-quality print is obtained, which is preferable.

In ink jet recording, a water-soluble dye is usually used as a coloring material. However, since this water-soluble dye has high hydrophilicity, it is usually stored for a long time under high humidity after printing, Dyes tend to bleed when water drops adhere to it.

In order to solve this problem, it is common practice to add a dye-fixing substance to the ink-receiving layer. Such a dye-fixing agent is, for example, an inorganic substance having a cationic surface. Examples include pigments (alumina fine particles and the like) and cationic polymers having an intramolecular quaternary ammonium salt.

However, when the ink absorbing layer is a void layer, the ink absorbing layer is excellent in ink absorbing property and a uniform image without unevenness can be obtained at the time of ink jet recording. On the other hand, since the porous film is used, oxygen permeability is large. Light resistance after recording tends to deteriorate. As a result of investigations by the present inventors, it has been found that such a problem occurs particularly in a place where air easily circulates.

[0007] In order to improve such deterioration of light fastness, many proposals have been made to add an ultraviolet absorber and various antioxidants.

However, in the case of an ink jet recording paper having a void layer having high oxygen permeability on a non-water-absorbing support, a sufficient effect was not necessarily obtained.

Japanese Patent Publication No. 2-35675 describes an ink jet recording paper in which a polyalkylene polyamine / dicyandiamidammonium salt condensate is used as a cationic resin to improve light resistance. Further, Japanese Unexamined Patent Publication No.
No. 254529 describes an ink jet recording paper in which a polyalkylene polyamine dicyandiamide condensate containing no quaternary ammonium salt structure is used to prevent white background yellowing and discoloration and to improve water resistance.

[0010] However, in the ink jet recording paper described in the above publication, only those using a water-absorbing support as the support are described. There is a problem in that a sufficient effect cannot be obtained, and when a large amount is added in order to obtain a sufficient effect on discoloration with respect to oxygen, light resistance may be deteriorated or ink absorption may be deteriorated.

[0011]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide an ink jet recording paper having improved oxygen fading and light fastness without deteriorating the ink absorbency.

[0012]

The above object of the present invention is attained by the following constitutions. 1. In an ink jet recording paper having an ink absorbing layer on a non-water-absorbing support, the ink absorbing layer contains at least inorganic fine particles, a hydrophilic binder and a nitrogen-containing compound, and a cross section in the film thickness direction is measured by X-ray photoelectron spectroscopy. The measured peak area ratio (N1S / C1S) of carbon atom 1S and nitrogen atom 1S not forming an ammonium salt is 0.01 to 0.1.
2, which is 1 from the surface of the entire thickness of the ink absorbing layer.
3. The ink jet recording paper according to claim 1, wherein the peak area ratio of the third portion is higher than the peak area ratio of the other portions by 0.01 or more. 2. 2. The ink jet recording paper according to claim 1, wherein the inorganic fine particles are silica. 3. 3. The ink jet recording paper according to claim 1, wherein the hydrophilic binder is polyvinyl alcohol. 4. The inkjet recording paper according to claim 3, wherein the ink absorbing layer contains boric acid or a salt thereof. 5. The ink-jet recording paper according to any one of claims 1 to 4, wherein the ink absorption layer is a void layer.

Hereinafter, the present invention will be described in detail.

The ink jet recording paper of the present invention is a swellable ink jet recording paper in which the ink absorbing layer provided on the support has a hydrophilic binder and the ink absorbing layer swells during ink jet recording to receive the ink. The present invention can be applied to both the case and the case of a gap type ink jet recording paper in which the ink absorption layer forms a gap layer having an inorganic pigment and a small amount of a hydrophilic binder. The ink absorbing layer of the present application, the layer that absorbs ink includes all,
Other functions may be provided.

However, in recent years, high ink absorbency has been increasingly required. In particular, a void-type ink absorbable layer is preferable in terms of image quality, dryness after recording, or water resistance of the film.

It is preferable that the support itself has excellent water resistance. The support having excellent water resistance is generally a non-porous support, and the effect of the present invention is particularly large when the ink absorbing layer provided thereon has a void structure.

Hereinafter, a particularly preferred void type ink absorbing layer will be described.

The void-type ink absorbing layer has inorganic fine particles and a small amount of a hydrophilic binder.

Examples of the inorganic fine particles include light calcium carbonate, heavy calcium carbonate, magnesium carbonate, kaolin, clay, talc, calcium sulfate, barium sulfate, titanium dioxide, zinc oxide, zinc hydroxide, zinc sulfide, and carbonate. Zinc, hydrotalcite, aluminum silicate, diatomaceous earth, calcium silicate, magnesium silicate, synthetic amorphous silica, colloidal silica, alumina,
Examples include white inorganic pigments such as colloidal alumina, pseudoboehmite, aluminum hydroxide, lithopone, zeolite, and magnesium hydroxide.

Such inorganic fine particles can be used as they are as primary particles or in a state where secondary aggregated particles are formed. It is preferable to use inorganic fine particles having a size of 1 to 0.01 μm.

In the present invention, fine particles having a low refractive index are preferred from the viewpoint of low cost and high reflection density. The inorganic fine particles having an anionic surface are synthesized by a gas phase method. Silica or colloidal silica is more preferred.

As the inorganic fine particles having a cationic surface, fumed silica treated with a cationic surface, colloidal silica and alumina treated with a cationic surface, alumina, colloidal alumina, pseudoboehmite and the like can also be used.

Examples of the hydrophilic binder used for the ink absorbing layer include polyvinyl alcohol, gelatin, polyethylene oxide, polyvinylpyrrolidone, polyacrylic acid, polyacrylamide, polyurethane, dextran, dextrin, and color ginnan (κ, ι, λ).
Etc.), agar, pullulan, water-soluble polyvinyl butyral,
Hydroxyethyl cellulose, carboxymethyl cellulose and the like can be mentioned.

These hydrophilic binders can be used in combination of two or more kinds.

The hydrophilic binder preferably used in the present invention is polyvinyl alcohol.

The polyvinyl alcohol preferably used in the present invention includes, in addition to ordinary polyvinyl alcohol obtained by hydrolyzing polyvinyl acetate, polyvinyl alcohol having a cation-modified terminal or anion-modified polyvinyl alcohol having an anionic group. Of modified polyvinyl alcohol.

The polyvinyl alcohol obtained by hydrolyzing vinyl acetate preferably has an average degree of polymerization of 1000 or more, and particularly preferably has an average degree of polymerization of 1500 to 5000.
Is preferably used.

The degree of saponification is preferably from 70 to 100%, particularly preferably from 80 to 99.5%.

As the cation-modified polyvinyl alcohol, for example, a primary to tertiary amino group or a quaternary ammonium group as described in JP-A No. 61-10483 can be added to the main chain or side chain of the polyvinyl alcohol. Which is obtained by saponifying a copolymer of an ethylenically unsaturated monomer having a cationic group and vinyl acetate.

Examples of the ethylenically unsaturated monomer having a cationic group include trimethyl- (2-acrylamido-2,2-dimethylethyl) ammonium chloride and trimethyl- (3-acrylamido-3,3-dimethylpropyl). Ammonium chloride, N-vinylimidazole, N-vinyl-2-methylimidazole, N
-(3-dimethylaminopropyl) methacrylamide,
Hydroxylethyltrimethylammonium chloride, trimethyl- (2-methacrylamidopropyl) ammonium chloride, N- (1,1-dimethyl-3-
Dimethylaminopropyl) acrylamide and the like.

The ratio of the cation-modified group-containing monomer of the cation-modified polyvinyl alcohol is 0.1 to 10 mol%, preferably 0.2 to 5 mol%, based on vinyl acetate.

The anion-modified polyvinyl alcohol is, for example, a polyvinyl alcohol having an anionic group as described in JP-A-1-2060888, JP-A-61-237681, and JP-A-63-307979.
And copolymers of vinyl alcohol and a vinyl compound having a water-soluble group as described in
Modified polyvinyl alcohol having a water-soluble group as described in -285265.

Examples of the nonion-modified polyvinyl alcohol include polyvinyl alcohol derivatives described in JP-A-7-9758, in which a polyalkylene oxide group is added to a part of vinyl alcohol, and JP-A-8-25795. And a block copolymer of a vinyl compound having a hydrophobic group and vinyl alcohol described in Japanese Patent Application Laid-Open Publication No. H11-157,086.

Two or more kinds of polyvinyl alcohols, such as different degrees of polymerization and different types of modification, can be used in combination.

The amount of the inorganic fine particles used in the ink absorbing layer is determined by the required ink absorbing capacity, the porosity of the void layer,
Although it largely depends on the type of inorganic fine particles and the type of hydrophilic binder, generally 5 to 3
0 g, preferably 10 to 25 g.

The ratio of the inorganic fine particles to the hydrophilic binder used in the ink absorbing layer is usually 2: 1 to 2 by weight.
0: 1, particularly preferably 3: 1 to 10: 1.

The nitrogen-containing compound used in the ink absorbing layer is not limited as long as it has a function as an antioxidant. For example, hydrazides described in JP-A-61-154989, JP-A-61-177279, and JP-A-Heisei 3 No. 13376, hindered amine antioxidants, JP-A-9-26754
Examples thereof include a hydroxylamine derivative described in No. 4, but a compound containing no quaternary ammonium salt structure and having many nitrogen atoms in the molecule is preferable, and a polymer such as polyamine and polyamide is preferable.

Particularly preferred compounds are polyalkylenepolyamine / dicyandiamide-based polycondensates and formalin / dicyandiamide-based polycondensates, and are polycondensates of polyalkylenepolyamine and dicyandiamide. Examples of the polyalkylene polyamine include diethylenetriamine, triethylenetetramine, tetraethylenepentamine, iminobispropylamine, and hydrochlorides, sulfates, and acetates thereof. The formalin / dicyandiamide condensate is a polycondensate obtained by a methylolation reaction between formalin and dicyandiamide.

The addition amount of the nitrogen-containing compound of the present invention is determined by measuring the peak area of carbon atom 1S and nitrogen atom 1S which is not an ammonium salt when a cross section of the ink absorbing layer in the thickness direction is measured by X-ray photoelectron spectroscopy. The ratio (N1S / C1S) is 0.0
It is necessary that the content is 1 to 0.2 so that the area ratio of a portion of 1/3 from the surface of the entire film thickness is 0.01 or more higher than the area ratio of other portions.

Therefore, although it depends on the amount of the hydrophilic binder in the absorbing layer, it is generally 0.05 to 5 per m2 of the recording paper.
g, preferably in the range of 0.1 to 2 g.

For analyzing the element distribution in the thickness direction of the ink absorbing layer, it is effective to use a cross-sectional sample prepared by a microtome or the like. Measurements include EPMA (X-ray microanalyzer), AES (Auger electron spectroscopy), SIM
S method (secondary ion mass spectrometry) can be used, but XP that is less affected by beam damage (changes in structure or composition due to the influence of electrons or heat during measurement)
It is preferable to use the S method (X-ray Photoelectron Spectroscopy). The XPS method is a method of qualitatively and quantitatively measuring an element by irradiating the element with X-rays and measuring the kinetic energy of specific photoelectrons emitted from the element. By measuring the ink absorption layer by the XPS method,
Area ratio of the C1s peak of carbon derived from the hydrophilic binder and the N1s peak of nitrogen derived from the nitrogen-containing compound (N1s / C1s)
Can be used as an index of the abundance ratio of the hydrophilic binder and the like and the nitrogen-containing compound in the ink absorbing layer.

The peak area ratio of the cross section of the present application is 0.01 to
A value of 0.2 means that the beam falls on any part of the cross section and the measurement is performed. In the case where there are a plurality of ink absorbing layers, the film thickness of the entire ink absorbing layer refers to the sum of the film thicknesses. The peak area ratio of a 1/3 portion from the surface is obtained from a value obtained by aligning the beam center with a central portion of a 1/3 film thickness from the surface (a portion having a further half thickness of the 1/3 film thickness). Value.

The peak area ratio (N1s / C1s) of a portion approximately 1/3 from the surface of the whole film thickness is lower than or equal to the peak area ratio of the portion closer to the support, or at most 0.0%.
If it is less than 1, the lightfastness may be rather deteriorated even though the discoloration to oxygen is improved by the addition.
Although the mechanism is not clear, it seems necessary to localize the nitrogen-containing compound of the present invention in the vicinity of the outermost layer in order to achieve both fading by oxygen and light resistance.

The ink jet recording paper of the present invention is preferably hardened with a hardening agent in order to obtain a high porosity without deteriorating the brittleness of the film, with excellent gloss. .

The hardener is generally a compound having a group capable of reacting with the hydrophilic binder or a compound which promotes a reaction between different groups of the hydrophilic binder. It is appropriately selected and used depending on the situation.

Specific examples of hardeners include, for example, epoxy hardeners (diglycidyl ethyl ether, ethylene glycol diglycidyl ether, 1,4-butanediol diglycidyl ether, 1,6-diglycidyl cyclohexane, N , N-diglycidyl-4-glycidyloxyaniline, sorbitol polyglycidyl ether, glycerol polyglycidyl ether, etc., aldehyde hardeners (formaldehyde, glyoxal, etc.), active halogen hardeners (2,4-dichloro-4-) Hydroxy-1,3,5-s-triazine, etc.), active vinyl compounds (1,3,5-trisacryloyl-hexahydro-)
s-triazine, bisvinylsulfonyl methyl ether, etc.), boric acid and its salts, borax, aluminum alum and the like.

When polyvinyl alcohol and / or cation-modified polyvinyl alcohol are used as a particularly preferred hydrophilic binder, boric acid and its salts,
It is preferable to use a hardening agent selected from epoxy hardeners.

Most preferred are hardeners selected from boric acid and its salts.

In the present invention, boric acid or a salt thereof is
Oxygen acid having a boron atom as a central atom and salts thereof, and specifically include orthoboric acid, diboric acid, metaboric acid, tetraboric acid, pentaboric acid, octanoic acid and salts thereof.

The amount of the hardener used varies depending on the type of the hydrophilic binder, the type of the hardener, the type of the inorganic fine particles, the ratio to the hydrophilic binder, and the like. Is 10-30
0 mg.

The above-mentioned hardener may be added to the water-soluble coating solution for forming a water ink absorbing layer of the present invention when the coating solution is applied, or a coating solution containing a hardener may be applied in advance. The ink-absorbing layer-forming water-soluble coating liquid of the present invention may be applied onto a support that has been formed. In addition, after applying and drying the water-soluble coating solution for forming the ink absorbing layer (containing no hardener) of the present invention, the hardener solution can be supplied by overcoating or the like. From the viewpoint of production efficiency, preferably, a method of adding a hardener to the water-soluble coating solution for forming an ink absorbing layer of the present invention and applying the solution is preferred.

Various additives other than those described above can be added to the ink absorbing layer of the ink jet recording paper of the present invention and other layers provided as necessary.

Above all, cationic polymers are preferably used because they can improve the water resistance and moisture resistance of characters and images after printing. As the cationic polymer, a polymer having a primary to tertiary amino group and a quaternary ammonium salt is used. However, a quaternary ammonium salt is used because of less discoloration and deterioration of water resistance over time and a high fixing ability of the dye. Is preferred. Preferred cationic polymers are obtained as a homopolymer of the above-mentioned monomer having a quaternary ammonium salt or as a copolymer with another monomer.

The cationic water-soluble polymer is used in an amount of usually 0.1 to 10 g, preferably 0.2 to 5 g per 1 m 2 of the ink jet recording paper.

In addition to the above, polystyrene, polyacrylates, polymethacrylates, polyacrylamides, polyethylene, polypropylene, polyvinyl chloride, polyvinylidene chloride, or copolymers thereof, urea resins, or melamine resins Organic latex fine particles, such as cationic or nonionic surfactants, ultraviolet absorbers described in JP-A-57-74193, JP-A-57-87988 and JP-A-62-261476; Nos. 74192, 57-87989, 60-72785, 61-14659
No. 1, JP-A-1-95091 and 3-13
No. 376, etc .;
Nos. 9-42993, 59-52689, 62-280069, 61-242871, JP-A-4-219266, etc., fluorescent brighteners, sulfuric acid, phosphoric acid, Various known additives such as a pH adjuster such as citric acid, sodium hydroxide, potassium hydroxide, and potassium carbonate, an antifoaming agent, a preservative, a thickener, an antistatic agent, and a matting agent can also be contained.

The ink absorbing layer may be composed of two or more layers. In this case, the constitutions of the ink absorbing layers may be the same or different.

The non-water-absorbing support used in the ink jet recording paper of the present invention includes a transparent support and an opaque support.

The transparent support is made of, for example, a polyester resin, a diacetate resin, a triacetate resin, an acrylic resin, a polycarbonate resin, a polyvinyl chloride resin, a polyimide resin, cellophane, celluloid or the like. Film and the like.
Those having the property of resisting radiant heat when used as HP are preferable, and polyethylene terephthalate is particularly preferable. The thickness of such a transparent support is about 10 to
200 μm is preferred. It is preferable to provide a known undercoat layer on the ink receiving layer side and the back layer side of the transparent support from the viewpoint of improving the adhesion between the ink receiving layer and the back layer and the support.

As the support used when it is not necessary to be transparent, for example, resin-coated paper (so-called RC paper) having a polyolefin resin-coated layer obtained by adding a white pigment or the like to at least one of base paper, polyethylene terephthalate White pets in which a white pigment has been added are preferred.

Prior to the application of the ink receiving layer, for the purpose of increasing the adhesive strength between the support and the ink image receiving layer,
The support is preferably subjected to a corona discharge treatment, an undercoating treatment, or the like. Furthermore, the recording paper of the present invention does not necessarily need to be colorless, and may be a colored recording paper.

In the ink jet recording paper of the present invention, the use of a paper support in which both sides of the base paper support are laminated with polyethylene is particularly preferable since the recorded image is close to photographic quality and a high quality image can be obtained at low cost. preferable.
Such a paper support laminated with polyethylene is described below.

The base paper used for the paper support is made of wood pulp as a main raw material, and if necessary, is made of synthetic pulp such as polypropylene or synthetic fiber such as nylon or polyester in addition to wood pulp. As wood pulp, LBKP, LBSP, NBKP, NBSP, LD
Any of P, NDP, LUKP, and NUKP can be used, but LBKP, NBSP, and LBS containing a large amount of short fibers
It is preferable to use more P, NDP, and LDP.
However, the ratio of LBSP and / or LDP is 10% by weight.
~ 70% by weight is preferred.

As the pulp, a chemical pulp containing less impurities (sulfate pulp or sulfite pulp) is preferably used, and pulp having improved whiteness by performing a bleaching treatment is also useful.

In the base paper, sizing agents such as higher fatty acids and alkyl ketene dimers, white pigments such as calcium carbonate, talc and titanium oxide, paper strength agents such as starch, polyacrylamide and polyvinyl alcohol, fluorescent whitening agents, Water retention agents such as polyethylene glycols, dispersants, and softening agents such as quaternary ammonium can be appropriately added.

The freeness of the pulp used for papermaking is preferably 200 to 500 cc according to the specification of CSF, and the fiber length after beating is 24% by weight of the remaining 24 mesh specified in JIS-P-8207. The sum with the calculated weight% is 3
0-70% is preferred. The weight percentage of the remaining 4 mesh
Is preferably 20% by weight or less.

The basis weight of the base paper is preferably 30 to 250 g,
Particularly, 50 to 200 g is preferable. Base paper thickness is 40-2
50 μm is preferred.

The base paper may be calendered at the papermaking stage or after the papermaking to provide high smoothness. The base paper density is generally 0.7 to 1.2 g / m2 (JIS-P-8118). Further, the rigidity of the base paper is preferably from 20 to 200 g under the conditions specified in JIS-P-8143.

A surface sizing agent may be applied to the surface of the base paper. As the surface sizing agent, the same sizing agent as can be added to the base paper can be used.

The pH of the base paper is preferably 5 to 9 as measured by the hot water extraction method specified in JIS-P-8113. The polyethylene covering the front and back surfaces of the base paper is mainly low-density polyethylene. Polyethylene (LDP
E) and / or high density polyethylene (HDPE)
However, other LLDPE, polypropylene and the like can be partially used.

In particular, the polyethylene layer on the ink receiving layer side is preferably a layer obtained by adding rutile or anatase type titanium oxide to polyethylene to improve opacity and whiteness as widely used in photographic printing paper. The content of titanium oxide is usually 3 to 20% by weight, preferably 4 to 13% by weight based on polyethylene.

The polyethylene-coated paper may be used as a glossy paper, or may be subjected to a so-called embossing process when the polyethylene is melt-extruded onto the base paper surface and coated to obtain a matte surface or a silk surface which can be obtained with ordinary photographic printing paper. Those having a surface can also be used in the present invention.

The amount of polyethylene used on the front and back of the base paper is selected so as to optimize the curl at low and high humidity after the ink receiving layer and the back layer are provided. Is in the range of 20 to 40 μm, and the back layer side is in the range of 10 to 30 μm.

Further, the polyethylene-coated paper support preferably has the following characteristics. Tensile strength: The strength specified in JIS-P-8113 is preferably 2 to 30 kg in the vertical direction and 1 to 20 kg in the horizontal direction. Tear strength: 10 to 10 in the vertical direction according to the method specified in JIS-P-8116. 200 g, preferably 20 to 200 g in the horizontal direction. Compressive modulus ≧ 103 kgf / cm 2 is preferable. Surface Beck smoothness: 20 seconds or more is preferable as a glossy surface under the conditions specified in JIS-P-8119. Opacity: Under the measurement conditions of linear light incidence / diffuse light transmission conditions, the transmittance for visible light rays is preferably 20% or less, particularly preferably 15% or less.

The method for applying various hydrophilic layers, which are appropriately provided as necessary, such as a void layer and an undercoat layer, on the support of the recording paper of the present invention can be appropriately selected from known methods. A preferred method is obtained by applying a coating solution constituting each layer on a support and drying it. In this case, 2
More than one layer can be coated simultaneously, and in particular, simultaneous coating is preferable, in which all the hydrophilic binder layers need only be coated once.

As a coating method, a roll coating method, a rod bar coating method, an air knife coating method, a spray coating method, a curtain coating method or an extrusion coating method using a hopper described in US Pat. No. 2,681,294 is preferably used.

When recording an image using the ink jet recording paper of the present invention, a recording method using an aqueous ink is preferably used.

The aqueous ink is a recording liquid having the following colorant, liquid medium, and other additives. As the colorant, a water-soluble dye or a water-dispersible pigment such as a direct dye, an acid dye, a basic dye, a reactive dye, or a food colorant known by inkjet can be used.

Examples of the solvent for the aqueous ink include water and various water-soluble organic solvents, for example, alcohols such as methyl alcohol, isopropyl alcohol, butyl alcohol, tert-butyl alcohol and isobutyl alcohol;
Amides such as dimethylformamide and dimethylacetamide; ketones or ketone alcohols such as acetone and diacetone alcohol; ethers such as tetrahydrofuran and dioxane; polyalkylene glycols such as polyethylene glycol and polypropylene glycol; ethylene glycol, propylene glycol and butylene Polyhydric alcohols such as glycol, triethylene glycol, 1,2,6-hexanetriol, thiodiglycol, hexylene glycol, diethylene glycol, glycerin, triethanolamine; ethylene glycol methyl ether, diethylene glycol methyl (or ethyl) ether; And lower alkyl ethers of polyhydric alcohols such as triethylene glycol monobutyl ether.

Among these many water-soluble organic solvents,
Preferred are polyhydric alcohols such as diethylene glycol, triethanolamine and glycerin, and lower alkyl ethers of polyhydric alcohols such as triethylene glycol monobutyl ether.

Other additives for the aqueous ink include, for example, a pH adjuster, a metal sequestering agent, a fungicide, a viscosity adjuster,
Surface tension adjusters, wetting agents, surfactants, rust inhibitors, and the like.

The water-based ink liquid is usually 25 to 60 d at 20 ° C. in order to improve the wettability on the recording paper.
It preferably has a surface tension in the range of yn / cm, preferably 30 to 50 dyn / cm.

[0082]

EXAMPLES The present invention will be specifically described below with reference to examples of the present invention, but embodiments of the present invention are not limited to these examples.

In the examples, “%” indicates absolute dry weight% unless otherwise specified. Example 1 "Preparation of coating solution" 25% aqueous solution of cationic polymer 1 7
840 g of a 16% aqueous dispersion of fumed silica (Aerosil 300 manufactured by Nippon Aerosil Co., Ltd.) was added to 5 g, and 100 g of the dispersion was added.
It was finished to 0 ml and dispersed with a high-pressure homogenizer (manufactured by Sanwa Kikai Co., Ltd.) (dispersion liquid-1). Using Dispersion-1, a coating solution having the following composition was prepared at 40 ° C. Cationic polymer 1 First layer coating solution Dispersion-1 620 ml Polyvinyl alcohol (Kuraray Co., Ltd., PVA235) 5% aqueous solution 270 ml Nitrogen-containing compound of the present invention Amount shown in Table 1 5% solution Boric acid 5% aqueous solution 50 ml Except for the amount of the nitrogen-containing compound shown, coating solutions for the second and third layers were prepared in the same manner as for the first layer. "Preparation of recording paper" Polyethylene-coated paper in which both sides of a base paper having a thickness of 170 g / m2 were coated with polyethylene (containing 8% by weight of anatase type titanium oxide in polyethylene on the ink receiving layer side; 0.05 g on the ink receiving layer side) / M2 gelatin undercoat layer, on the opposite side, a latex polymer having a Tg of about 80 ° C as a back layer of 0.2 g / m2)
In the order of the first to third layers from the polyethylene coated paper side, the wet film thickness is 70 μm and the total thickness is 210 μm.
Coating was performed with a slide hopper so that the temperature became 60 ° C immediately after coating in a cooling zone maintained at 0 ° C for 20 seconds.
And dried for 3 minutes in the air. The ink jet recording paper obtained above was evaluated by the following measurement method.

(1) Measurement of the area ratio between carbon C1s peak and nitrogen N1s peak (N1s / C1s) The measurement was performed using a QUANTUM2000 scanning X-ray photoelectron spectrometer manufactured by Phi Corporation. X-ray source is AlKα ray
The line beam diameter was measured at 10 μmφ or less. The photoelectron capture angle (the angle between the sample surface and the central axis of the analyzer) is 90
Degree. The energy resolution was set so that the reversal width of the Ag3d5 / 2 peak when a clean silver plate was measured was 1.0 ± 0.05 eV.

The measurement was made by dividing the film thickness observed from the cross-sectional direction into three parts, the lower layer, the middle layer, and the upper layer from the side closer to the support, and the center of each layer. The peak area was determined as the area intensity of the peak obtained by removing the background from the obtained peak (CPS × eV: the sum of the detection intensities per unit time for each binding energy). In the photoelectron peak, a change in the peak shape called a chemical shift due to the difference in the bonding state is usually observed, but the intensity of all the peaks of the C1s photoelectron peak of the carbon atom was calculated. The nitrogen atom was calculated as the intensity excluding the peak derived from the ammonium salt after performing the waveform processing among the peaks obtained by measuring the N1s photoelectron peak. The chemical shift due to the difference in the bonding of nitrogen atoms is
You can refer to NDBOOK OF X-RAY PHOTOELECTRON SPECTROSCOPY (published by Phi USA).

(2) Light fastness Wedge images of Y, M and C were printed by an ink jet printer PM750C manufactured by Seiko Epson Corporation.

The obtained print image was irradiated with light with an Xe fade meter at an illuminance of about 50,000 Lux for 120 hours. The ratio of the reflection densities before and after light irradiation was used as a measure of light fastness as the residual dye ratio. Dye residual rate = 100 × (density after light irradiation) / initial density (=
1.0) (3) Indoor Fading Property The following water-based ink was prepared, and a wedge image was printed by changing the amount of ink using an ink jet printer.

The obtained printed image was subjected to a fluorescent lamp fading tester at a temperature and humidity of 3 on a print surface of about 2000 Lux.
Light irradiation was performed for 30 days and 90 days under the conditions of 0 ° C./75% RH. The ratio of the reflection densities before and after the irradiation of the fluorescent lamp was used as a measure of light fastness as a residual dye ratio. Dye residual rate = 100 × (density after fluorescent lamp irradiation) / initial density
(= 1.0) <Ink composition> Phthalocyanine cyan dye 2 parts by weight Glycerin 6 parts by weight Ethylene glycol 20 parts by weight Water 74 parts by weight (4) Ink absorbency Image printing using inkjet printer PM700C manufactured by Seiko Epson Corporation. (High-definition color digital standard image data "N5 Bicycle", published by the Japan Standards Association December 1995).

The chart portion and the clock portion of the obtained print were visually judged, and the ink absorption speed was evaluated based on the following criteria.

(A) No color bleeding at the boundary between the clock portion and the chart portion. (B) Slight bleeding at the boundary is observed at the clock portion, but no bleeding at the chart portion.

(C) Characters are almost crushed in the clock part, and bleeding occurs in less than half of the boundary area in the chart part. (D) Border color bleeding is observed in most of the boundary part of the chart. Table 1 shows the obtained results.

[0092]

[Table 1]

From the results shown in Table 1, the area ratio of carbon C1s peak to nitrogen N1s peak (N1s / C1s) was 0.01 to 0.2.
Since the area ratio of approximately 1/3 from the surface of the entire film thickness is higher than the area ratio of the other portions by 0.01 or more, the light fading property and the indoor light fastness are improved without impairing the ink absorbency. You can see that it is done.

On the other hand, when the peak area ratio of about ３ of the surface is lower or equal to or higher than that of the other parts, and is less than 0.01, the light fastness is improved even if the discoloration to oxygen is improved. Rather deteriorates (recording paper 2,
3, 10). If the peak area ratio exceeds 0.2,
It can be seen that the ink absorptivity is deteriorated, and the light resistance and the indoor fading property are rather deteriorated (recording papers 12 and 13).

[0095]

As demonstrated in the examples, the ink jet recording paper of the present invention and the method for producing the same have improved light fastness and indoor fading without adversely affecting the ink absorption speed, and have excellent effects.

Claims (5)

[Claims] 1. An ink-jet recording sheet having an ink-absorbing layer on a non-water-absorbing support, wherein the ink-absorbing layer contains at least inorganic fine particles, a hydrophilic binder and a nitrogen-containing compound, and has a cross-section in the thickness direction of X. The peak area ratio (N1S / C1S) of carbon atom 1S and nitrogen atom 1S which is not ammonium salt measured by X-ray photoelectron spectroscopy is 0.
01 to 0.2, wherein the peak area ratio of a portion 1/3 from the surface of the film thickness of the entire ink absorbing layer is 0.01 or more higher than the peak area ratio of other portions. Ink jet recording paper. 2. The ink jet recording paper according to claim 1, wherein the inorganic fine particles are silica. 3. The ink jet recording paper according to claim 1, wherein the hydrophilic binder is polyvinyl alcohol. 4. The ink jet recording paper according to claim 3, wherein said ink absorbing layer contains boric acid or a salt thereof. 5. The ink jet recording paper according to claim 1, wherein the ink absorbing layer is a void layer.