JP2003145920A - Ink jet recording medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ink jet recording medium, with which a recorded matter, the discoloring and fading of the recorded image of which hardly develop over a long period of time and consequently the long term preservation of the recorded image is possible. SOLUTION: The ink jet recording medium has an ink accepting layer on a support under the condition that the ink accepting layer includes a compound having a phenolic hydroxyl group and a salt comprising a weak acid and a strong base.

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 medium having an ink receiving layer on a substrate, and more specifically, to a recorded matter which is resistant to discoloration and fading of a recorded image for a long period of time and can be stored for a long period of time. The present invention relates to an inkjet recording medium that can be provided.

[0002]

2. Description of the Related Art An ink jet recording method is a recording method in which ink droplets are ejected from minute nozzles in accordance with an image signal and adhered to a recording medium for printing. Since a large amount of ink is used to form a high-quality full-color image comparable to a silver salt photograph, a recording medium is required to have a high ink absorbing ability. In recent years, a plurality of dark and light inks having the same color tone but different colorant concentrations have been used in order to reduce the graininess of highlights and form higher quality images. The level of absorbency is increasing. Therefore, as a recording medium (inkjet recording medium) for inkjet recording, which has a high ink absorption capacity and can form a high-quality full-color image comparable to a silver salt photograph, colloidal silica is formed on a substrate such as paper or film. An ink jet recording medium having a so-called void-type ink receiving layer, which mainly contains an inorganic ultrafine particle pigment such as vapor phase silica, alumina hydrate, and γ-type aluminum oxide, has been developed.

On the other hand, with the expansion of ink jet recording technology to digital photo services and commercial printing applications, the robustness of recorded images is becoming more and more important, and due to the influence of light, ozone gas, etc. for a long period of time. It is desired to provide an inkjet recording technique that can provide a recorded matter that is unlikely to undergo discoloration and fading and that can be stored for a long period of time. As one of such ink jet recording techniques, there is known a technique in which a phenolic antioxidant is contained in an ink receiving layer to improve the light resistance and gas resistance of a recorded matter (for example, Japanese Patent Laid-Open Publication No. Sho. 57-87989, JP-A-62-261477, JP-A-1-18684, and JP-A-2000-2.
80612, JP 2001-150796 A, JP 2001-30620 A, etc.). However, when this type of phenolic antioxidant is contained in the void-type ink receiving layer, the light resistance and gas resistance of the recorded image itself are improved, but the void-type ink receiving layer itself does not emit light or ozone gas. Due to the influence of the above, it turned yellow over time, and eventually it was not possible to obtain a recorded matter that could be stored for a long period of time. A technique capable of providing a recorded matter that can be stored for a long period of time by improving the light resistance and gas resistance of an image formed on a void-type ink receiving layer without causing such so-called base yellowing is still provided. It has not been.

Therefore, an object of the present invention is to provide an ink jet recording medium capable of providing a recorded matter which is unlikely to cause discoloration and fading of a recorded image due to light or ozone gas and yellowing of the base material for a long period of time and which can be stored for a long period of time. To provide.

As a result of various studies on the ink jet recording medium having a so-called void type ink receiving layer on a substrate, the present inventors have found that an image formed by a coloring agent such as a dye in the void type ink receiving layer. By containing a salt consisting of a weak acid and a strong base having a film surface pH adjusting ability of the ink receiving layer together with the phenolic hydroxyl group having an antioxidant ability, the yellowing of the substrate due to the phenolic hydroxyl group is suppressed. It was found that the light resistance and gas resistance of recorded images can be improved.

[0006]

The present invention has been made based on the above findings, and in an ink jet recording medium having an ink receiving layer on a substrate, the ink receiving layer contains a phenolic hydroxyl group, a weak acid and a strong acid. The above object is achieved by providing an inkjet recording medium containing a compound having a salt consisting of a base.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION The inkjet recording medium of the present invention will be described below based on its preferred embodiments. The ink jet recording medium of this embodiment is provided with an ink receiving layer on one surface of a base material. The ink receiving layer is a porous layer mainly composed of an inorganic pigment and having innumerable voids in the layer, a so-called void type ink receiving layer, which contains a compound having a salt of a phenolic hydroxyl group, a weak acid and a strong base. It is characterized by containing.

In the present embodiment, the "compound having a phenolic hydroxyl group, a salt composed of a weak acid and a strong base" is (A) a compound having a phenolic hydroxyl group and (B) a salt composed of a weak acid and a strong base. Two types of compounds having the formula (1) may be used, or (C) a compound having a phenolic hydroxyl group and a salt composed of a weak acid and a strong base in the molecule may be used.

The compound (A) may be any one as long as it has an action of preventing the oxidation of a coloring agent such as a dye forming a recorded image, and it is known as an additive for a recording medium of this kind or a plastic. Phenolic antioxidants can be used. In particular, monohydric phenol or its derivative is preferable because it has a high antioxidant effect. (A)
Preferable compounds are p-methoxyphenol and 2,6-di-tert-butyl-4.
-Methoxyphenol, 2,6-di-tert-butyl-4-ethylphenol, 2,6-di-tert-butyl-p-cresol, 4,4'-butylidenebis- (6
-Tert-butyl-3-methylphenol), 2,
2'-methylenebis- (4-methyl-6-tert-butylphenol) and the like can be mentioned.

The content of the compound (A) is preferably 0.5 to 10% by weight, more preferably 1 to 5% by weight, based on the dry weight of the ink receiving layer. If the content is less than 0.5% by weight, the effect of improving the light resistance and gas resistance of the recorded image is poor, and if it exceeds 10% by weight, the yellowing of the base material (base yellowing) is deteriorated and the content of other components is increased. There is a risk that the ink absorbency and the coating film strength will decrease due to the decrease of the ink.

The above (B) used in combination with the above (A) compound
As a compound, the compound functions as a pH adjuster in the ink receiving layer and has a film surface pH of the ink receiving layer [Method A (coating method) [J] of the surface pH test method of paper and paper board specified by the Japan Pulp and Paper Technology Association. ． TAPPI No. 6], which means the pH measured according to [6], is used, and preferably, an inorganic acid such as phosphoric acid, carbonic acid, boric acid, sulfurous acid or acetic acid, tartaric acid, citric acid, benzoic acid, Alkali metal salts of organic acids such as phenolic acids can be used. In particular, alkali metal salts of carboxylic acids, especially lithium salts or sodium salts of carboxylic acids are preferable because they have a high effect of preventing yellowing of the substrate. As the compound preferably used as the compound (B),
Dipotassium hydrogen citrate, sodium benzoate, sodium tartrate, sodium lactate, sodium acetate and the like can be mentioned.

The content of the compound (B) is the same as that of the compound (A).
It is preferably 0.5 to 10 relative to 100 parts by weight of the compound.
Parts by weight, more preferably 1 to 5 parts by weight. If the content is less than the lower limit of the above range, it is not effective in preventing the yellowing of the substrate due to the compound (A), and if it exceeds the upper limit of the above range,
There is a possibility that the coating strength of the ink receiving layer may be reduced, the ink absorbency may be reduced, and the like.

On the other hand, examples of the compound (C) include an alkali metal salt of hydroxybenzoic acid or a derivative thereof and an alkali metal salt of hydroxyphenylacetic acid or a derivative thereof.

The content of the compound (C) is preferably 0.5 to 10% by weight, more preferably 1 to 5% by weight, based on the dry weight of the ink receiving layer. If the content is less than 0.5% by weight, the effect of improving the light resistance and gas resistance of the recorded image is poor, and if it exceeds 10% by weight, the yellowing of the base material (base yellowing) is deteriorated and the content of other components is increased. There is a risk that the ink absorbency and the coating film strength will decrease due to the decrease of the ink.

Particularly preferred as the above-mentioned "compound having a phenolic hydroxyl group, a salt consisting of a weak acid and a strong base" is sodium 3,5-di-tert-butylsalicylate, potassium 3,5-di-tert-butylsalicylate. , Sodium 2-hydroxyphenylacetate and sodium 4-hydroxyphenylacetate.

Examples of the inorganic pigment contained in the ink receiving layer include amorphous silica, colloidal silica and alumina (vapor phase method alumina, γ alumina) synthesized by a precipitation method, a gel method, a gas phase method or the like. Etc.), alumina hydrate (alumina sol, colloidal alumina, cationic aluminum oxide or its hydrate, pseudo-boehmite, etc.), smectite clay, calcium carbonate, calcium sulfate, barium sulfate, titanium dioxide, kaolin, clay, talc,
Magnesium silicate, calcium silicate, etc. are mentioned, and these 1 type (s) or 2 or more types are used. Also, a composite of an inorganic pigment and a resin (such as "Movinyl 8050" manufactured by Hoechst Synthetic Co., Ltd.) can be used. Of these,
Especially when using amorphous silica, high purity, high price,
It is preferable in terms of availability.

[0017] the inorganic pigment has a specific surface area by BET is 100 to 500 m ² / g, to be particularly 200 to 400 m ² / g, from the viewpoint of a balance between image quality and preservability of recorded images. From the same viewpoint, the average particle size of the inorganic pigment is preferably 0.05 to 15 μm, more preferably 0.1 to 10 μm. From the same viewpoint, the average primary particle diameter of the inorganic pigment is preferably 3-5.
It is 0 nm, more preferably 3 to 20 nm, and the average secondary particle diameter is preferably 0.05 to 15 nm, more preferably 0.1 to 10 nm.

The content of the inorganic pigment is preferably 40 to 90% by weight based on the dry weight of the ink receiving layer,
More preferably, it is 50 to 80% by weight. Content is 40
If it is less than wt%, sufficient ink absorbency may not be ensured, and if it exceeds 90 wt%, the coating strength of the ink receiving layer may be reduced.

The ink receiving layer contains a binder resin for fixing the inorganic pigment on the substrate.
As the binder resin, those commonly used in this type of coated paper can be used, and examples thereof include polyvinyl alcohol, silanol-modified polyvinyl alcohol, vinyl acetate, starch, cellulose derivatives such as carboxymethyl cellulose, casein, and gelatin. , Conjugated styrene copolymer latex such as styrene-butadiene copolymer, vinyl copolymer latex such as ethylene-vinyl acetate copolymer, acrylic copolymer latex such as acrylic acid and methacrylic acid polymer And one or more of these are used. In particular, it is preferable to use polyvinyl alcohol.

The content of the binder resin is preferably 5 to 60 parts by weight, more preferably 10 to 50 parts by weight, based on 100 parts by weight of the inorganic pigment. If the content is less than the lower limit of the above range, the coating strength of the ink receiving layer may be lowered, and if it exceeds the upper limit of the above range, the ink absorbability and the dye adsorbability may be reduced.

Further, in order to obtain a high image density, it is preferable that the ink receiving layer contains a dye fixing agent capable of being combined with a dye to be insoluble. As the dye fixing agent, cationic polymers; polyvalent metal ions such as Al ³⁺ , Ca ²⁺ and Mg ²⁺ ; cationic surfactants such as benzalkonium chloride can be used. Polymers are preferable in terms of water resistance, color development and the like. Examples of the cationic polymer include diallyldimethylammonium chloride polymer, epihalohydrin-secondary amine copolymer, diallyldimethylammonium chloride-sulfur dioxide copolymer, diallyldimethylammonium chloride-acrylamide copolymer, diallylmethylammonium salt polymer, diallylamine hydrochloride-sulfur dioxide copolymer. , Dimethylmethylamine hydrochloride copolymer, polyallylamine, polyethyleneimine, polyethyleneimine quaternary ammonium salt compound, (meth) acrylamidoalkylammonium salt polymer, ionene containing quaternary ammonium base, dicyandiamide / formalin polycondensate, dicyandiamide / diethylenetriamine Condensates and the like can be mentioned, and one or more of these can be used. Rukoto can. Particularly, it is preferable to use a diallyldimethylammonium chloride polymer.

The content of the dye fixing agent is preferably 1 to 30 parts by weight, more preferably 5 to 20 parts by weight, based on 100 parts by weight of the inorganic pigment. When the content is less than the lower limit of the above range, the effect of improving the color developability and water resistance of the recorded image is poor, and when the content exceeds the upper limit of the above range, high gloss (bronzing) due to a decrease in ink absorbency or precipitation of a colorant is caused. May invite.

In the ink receiving layer, if necessary, a fluorescent whitening agent, a fungicide, an antiseptic agent, a surfactant, a thickener, and a pH.
One or more kinds of various additives such as a regulator, a defoaming agent, a water retention agent, a hardener, a coloring dye, a coloring pigment, a pigment dispersant, a leveling agent, and an ultraviolet absorber can be contained.

The ink receiving layer was prepared by dispersing a compound having a phenolic hydroxyl group, a salt of a weak acid and a strong base, an inorganic pigment, a binder resin, a dye fixing agent and various other additives, if necessary, in water. The coating composition,
It can be formed by coating on a substrate by a known coating method such as a roll coater method, a blade coater method, an air knife coater method, a gate roll coater method, a size press method and drying. The thickness of the ink receiving layer after drying is not particularly limited, but is preferably 10 to 40 μm, and more preferably 20 to 30 μm from the viewpoint of color developability and prevention of powder falling. The coating amount is preferably 10 to 40 g / m ² , more preferably 20 in terms of dry weight.
Is about 30 g / m ² .

The ink receiving layer may be surface gloss finished by a casting method. The surface gloss finish is obtained by applying the coating composition onto a substrate, pressing it against a mirror-finished drum or a PET film which is heated while the coating composition is in a wet state, and drying the coated composition, and then the drum or film. Is peeled off and the mirror surface is transferred to the surface of the coating composition. In this case, the coating amount of the coating composition is preferably 0.2 to 30 g / m ² , more preferably 3 to 1 in terms of dry weight.
It is 0 g / m ² . The casting method includes a wet method, a rewet method and the like, and any method may be used, but the wet method is particularly preferable because excellent recording property is obtained.

The ink receiving layer may be formed according to J. TAPPI N
o. Porosity measured according to 48-85 is 30-80%
Is preferable, and 40 to 70% is more preferable. When the porosity is less than 30%, the quick-drying property of ink, absorption speed, absorption capacity, etc. are not sufficient, and when it exceeds 80%, slipping of the paper feed roll and clogging of the head may occur due to falling off of the inorganic pigment. The porosity of the ink receiving layer can be adjusted by adjusting the ratio of the inorganic pigment and the binder resin, calendering, adjusting the drying conditions (adjusting the coating film shrinkage), and the like.

The substrate on which the ink receiving layer is provided is not particularly limited, and is a paper such as high-quality paper, recycled paper, size-treated paper; art paper, coated paper, cast coated paper, resin-coated paper, resin-impregnated paper. Processed papers such as; Polyethylene, polypropylene, polystyrene, polyethylene terephthalate, etc. film or sheet plastic substrates; Non-woven fabrics, cloths,
A sheet material that is usually used as a base material in this type of coated paper, such as a woven fabric, a metal film, a metal plate; a composite base material obtained by sticking these together, can be used. It is particularly preferable to use polyolefin resin-coated paper.

The resin-coated paper used as the substrate in the present invention will be described. The resin-coated paper is obtained by providing a resin coating layer on one side or both sides of a base paper.

The base paper constituting the resin-coated paper is not particularly limited, and commonly used paper can be used, but more preferably, for example, a smooth base paper used for a photographic support is preferable. As the pulp that constitutes the base paper,
Examples include natural pulp, recycled pulp, synthetic pulp and the like, and one kind or a mixture of two or more kinds thereof can be used. Additives such as a sizing agent, a paper strength enhancer, a filler, an antistatic agent, an optical brightening agent and a dye, which are generally used in papermaking, are added to the base paper. Furthermore, a surface sizing agent, a surface paper strength agent, a fluorescent brightening agent, an antistatic agent, a dye, an anchoring agent, etc. may be applied on the surface. The thickness of the base paper is not particularly limited, but it is preferable that the paper has good surface smoothness, such as being compressed by applying pressure with a calendar or the like during or after paper making, and the basis weight is 30 to 250 g / m ²
Is preferred.

The resin (polyolefin resin) for coating the base paper is selected from two or more olefin homopolymers such as low density polyethylene, high density polyethylene, polypropylene, polybutene and polypentene; and olefins such as ethylene-propylene copolymer. And a mixture thereof, and those having various densities and melt viscosity indexes (melt indexes) can be used alone or in combination. In the above resins, white pigments such as titanium oxide, zinc oxide, talc and calcium carbonate; fatty acid amides such as stearic acid amide and arachidic acid amide; zinc stearate, calcium stearate, aluminum stearate, magnesium stearate, etc. Fatty acid metal salts of; Irganox 1010, Irganox 107
Antioxidants such as 6; blue pigments and dyes such as cobalt blue, ultramarine blue, cesian blue, phthalocyanine blue; magenta pigments and dyes such as cobalt violet, fast violet, manganese purple; fluorescent brighteners, ultraviolet absorbers, etc. It is preferable to add various kinds of additives in appropriate combination.

The resin-coated paper can be manufactured by a so-called extrusion coating method, in which a polyolefin resin is cast in a molten state on a running base paper. Before the base paper is coated with the resin, it is preferable that the base paper is subjected to activation treatment such as corona discharge treatment or flame treatment. In the present invention, at least the surface of the base paper (the surface on which the ink receiving layer is provided)
May be coated with a resin, but from the viewpoint of preventing curling, it is preferable that both sides of the base paper are coated with a resin. The back surface of the base paper is usually a matte surface, and the front surface or both front and back surfaces can be subjected to activation treatment such as corona discharge treatment or flame treatment as required. The thickness of the resin coating layer is not particularly limited, but is preferably about 5 to 50 μm on one side or both sides of the base paper. In the extrusion coating method, a polyolefin resin is heated and melted by an extruder, extruded in a film form between a base paper and a cooling roll, pressure-bonded and cooled. At that time, by appropriately changing the surface shape of the cooling roll, the surface of the resin coating layer is made to be a mirror surface or a finely rough surface, or a patterned pattern such as silk or mat is formed on the surface. You can

The ink jet recording medium of this embodiment is
Although it can be used for various recording methods such as a recording method using a writing instrument such as a pen, in particular, an ink jet recording method in which ink droplets are ejected from minute nozzles in accordance with an image signal and adhered to a recording medium for printing. Is perfect for That is, the inkjet recording medium of the present embodiment suppresses the yellowing of the substrate, which is a drawback of conventional phenolic antioxidants, by the action of the above-mentioned “compound having a salt consisting of a phenolic hydroxyl group, a weak acid and a strong base”. At the same time, since it is possible to improve the light resistance and gas resistance of the image formed on the ink receiving layer by a coloring agent such as a dye, it is an advantage that the void-type ink receiving layer containing the dye fixing agent is excellent. In addition to the ink absorptivity and color developability, it is possible to provide a recorded matter which has a high image quality comparable to a silver salt photograph and can be stored for a long period of time.

The present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the spirit of the invention. For example, the ink receiving layer may be provided not only on one side of the substrate but also on both sides.

[0034]

EXAMPLES The present invention will be described in more detail below with reference to Examples and Comparative Examples of the present invention and Test Examples, but the present invention is not limited to these Examples. .

[Example 1] A coating composition 1 having the following composition prepared separately was coated on the surface of a paper containing wood pulp as a main component and having a basis weight of 80 g / m ² so that the dry weight was 20 g / m ^2. Was coated with a roll coater and dried to form an ink receiving layer, thereby manufacturing an inkjet recording medium. This inkjet recording medium was used as a sample of Example 1.

Coating composition 1 60 parts by weight of silica (trade name "FINESEAL X37B" manufactured by Tokuyama Corporation) 300 parts by weight of polyvinyl alcohol (trade name "Gothenal T-330" manufactured by Nippon Synthetic Chemical Industry Co., Ltd.) 10 % Aqueous solution) -Cationic polymer 20 parts by weight (trade name "PAL-2" Senka Co., Ltd., 20% aqueous solution) -p-methoxyphenol (Kanto Chemical Co., Inc.) 3 parts by weight-dipotassium hydrogen citrate (Manufactured by Kanto Chemical Co., Inc.) 3 parts by weight, water 200 parts by weight

Example 2 An ink jet recording medium was produced in the same manner as in Example 1 except that the coating composition 1 was replaced with the coating composition 2 having the following composition. This was used as a sample of Example 2.

Coating composition 2 100 parts by weight of vapor phase silica (trade name "Aerosil 380" manufactured by Nippon Aerosil Co., Ltd.) 20 parts by weight polyvinyl alcohol (trade name "Gothenal T-330" Nippon Synthetic Chemical Co., Ltd. ), 10% aqueous solution) ・ Cationic polymer 8 parts by weight (trade name "Unisense C-104" manufactured by Senka Co., Ltd., 44% aqueous solution) ・ 2,6-di-tert-butyl-4-methoxyphenol 3 parts by weight Part (manufactured by Kanto Chemical Co., Inc.)-Sodium benzoate (manufactured by Kanto Chemical Co., Ltd.) 3 parts by weight-Boric acid 6 parts by weight-Surfactant 0.3 parts by weight-Denatured ethanol 20 parts by weight-Water 400 parts by weight

Example 3 An ink jet recording medium was produced in the same manner as in Example 1 except that the coating composition 1 was replaced by the coating composition 3 having the following composition. This was used as a sample of Example 3.

Coating composition 3 : 60 parts by weight of silica (trade name "Fineseal X37B" manufactured by Tokuyama Corporation) 300 parts by weight of polyvinyl alcohol (trade name "Gothenal T-330" manufactured by Nippon Synthetic Chemical Industry Co., Ltd.) 10 % Aqueous solution) -Cationic polymer 20 parts by weight (trade name "PAL-2" Senka Co., Ltd., 20% aqueous solution) -ADEKA STAB LX-141 5 parts by weight (trade name, Asahi Denka Kogyo Co., Ltd., active ingredient) 50%) ・ (+)-Sodium tartrate dihydrate (manufactured by Kanto Chemical Co., Inc.) 3 parts by weight Water 200 parts by weight

[Embodiment 4] Embodiment 1 is the same as Embodiment 1 except that the surface is finished by a casting method.
An ink jet recording medium was manufactured in the same manner as described above and used as a sample of Example 4. The surface gloss finish by this casting method was applied to the ink receiving layer of the sample of Example 1 by using a roll coater, which was prepared by adding water to a casting coating liquid having the following composition to give a solid content concentration of 30%. Immediately after, press contact with the mirror surface drum of surface temperature 85 ℃,
After drying, the mold was released.

Coating liquid for casting- Composite of colloidal silica and styrene-2-methylhexyl acrylate copolymer 100 parts by weight (trade name "Movinyl 8050" manufactured by Hoechst Synthesis Co., Ltd.)-Calcium stearate 1 part by weight-Carboxy Methyl cellulose 1 part by weight p-methoxyphenol (manufactured by Kanto Chemical Co., Inc.) 5 parts by weight dipotassium hydrogen citrate (manufactured by Kanto Chemical Co., Ltd.) 5 parts by weight

Example 5 An ink jet recording medium was produced in the same manner as in Example 1 except that the coating composition 1 was replaced with the coating composition 4 having the following composition. This was used as a sample of Example 5.

Coating composition 4 100 parts by weight of alumina (trade name "Alumina sol-520", manufactured by Nissan Chemical Industries, 20% aqueous solution) 80 parts by weight of polyvinyl alcohol (trade name "Gothenal T-330" Nippon Synthetic) Chemical Co., Ltd., 10% aqueous solution) -2,6-di-tert-butyl-4-methoxyphenol 1 part by weight (Kanto Chemical Co., Inc.)-Sodium benzoate (Kanto Chemical Co., Ltd.) 2 parts by weight Department

Example 6 <Preparation of polyethylene resin coated paper> Hardwood bleached kraft pulp (LBKP) and softwood bleached sulfite pulp (NB
A 1: 1 mixture of SP) was beaten with a Canadian standard freeness to 300 ml to prepare a pulp slurry, in which an alkyl ketene dimer as a sizing agent was added to 0.5% by weight of pulp and a polyacrylamide as a paper strengthening agent. Was added to 1% by weight of pulp, cationized starch was added to 2% by weight of pulp, and polyamide epichlorohydrin resin was added to 0.5% by weight of pulp, and diluted with water to obtain a 1% slurry. 170 g / basis weight of this slurry with a Fourdrinier paper machine
Paper was made to m ² and dried and conditioned to obtain a base paper for polyolefin resin-coated paper. Also, separately, density 0.91
The low density polyethylene 100% by weight of the resin of 8 g / cm ^3, a resin composition obtained by uniformly dispersing 10 wt% of anatase titanium, density 0.962 g / cm ³
70 parts by weight of high density polyethylene resin and a density of 0.91
No. 8 low density polyethylene resin 30 parts by weight blended resin composition was prepared. Then, the surface of the base paper (the surface on which the ink receiving layer is provided) was heated and melted at 320 ° C., and the resin composition was dried at 200 m / min to give a thickness of 30.
It is extrusion coated to have a thickness of μm, and extrusion coated using a slightly roughened cooling roll, and the thickness of the blended resin composition that has been heated and melted at 320 ° C. on the back surface of the base paper is 30 μm after drying. Was extrusion-coated to obtain a polyethylene resin-coated paper.

The polyethylene resin-coated paper thus obtained was coated with a coating composition 5 having the following composition in a dry weight of 30:
An inkjet recording medium was manufactured by applying a coating solution using a slide coating device so that the coating composition would be g / m ² and drying it to form an ink receiving layer. This inkjet recording medium was used as a sample of Example 6.

Coating composition 5 100 parts by weight of vapor phase silica (trade name "Aerosil 300" manufactured by Nippon Aerosil Co., Ltd.) 200 parts by weight of polyvinyl alcohol (trade name "Gothenal T-330" manufactured by Nippon Synthetic Chemical Co., Ltd. ), 10% aqueous solution) ・ Cationic polymer 4 parts by weight (brand name "Charol DC902P" manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) ・ Basic polyaluminum hydroxide 4 parts by weight (brand name "Purachem WT" RIKEN) Green, 10% aqueous solution) Sodium o-hydroxybenzoate (Kanto Chemical Co., Ltd.) 2 parts by weight Boric acid (Kanto Chemical Co., Ltd.) 3 parts by weight Surfactant 0.3 parts by weight Water 700 parts by weight

Comparative Example 1 An ink jet recording medium was produced in the same manner as in Example 1 except that the coating composition 1 was replaced with the coating composition 6 having the following composition. This was used as a sample of Comparative Example 1.

Coating composition 6 -Silica 60 parts by weight (trade name "Fineseal X37B" manufactured by Tokuyama Co., Ltd.)-Polyvinyl alcohol 300 parts by weight (trade name "Gosenal T-330" manufactured by Nippon Synthetic Chemical Industry Co., Ltd.) 10 % Aqueous solution) -Cationic polymer 20 parts by weight (trade name "PAL-2" Senka Co., Ltd., 20% aqueous solution) -p-methoxyphenol (Kanto Chemical Co., Inc.) 3 parts by weight Water 200 parts by weight

Comparative Example 2 An ink jet recording medium was produced in the same manner as in Example 1 except that the coating composition 1 was replaced with the coating composition 7 having the following composition. This was used as a sample of Comparative Example 2.

Coating composition 7 100 parts by weight of vapor phase silica (trade name "Aerosil 380" manufactured by Nippon Aerosil Co., Ltd.) 20 parts by weight of polyvinyl alcohol (trade name "Gothenal T-330" Nippon Synthetic Chemical Co., Ltd. ), 10% aqueous solution) ・ Cationic polymer 8 parts by weight (trade name "Unisense C-104" manufactured by Senka Co., Ltd., 44% aqueous solution) ・ 2,6-di-tert-butyl-4-methoxyphenol 3 parts by weight Part (manufactured by Kanto Chemical Co., Inc.) 6 parts by weight boric acid 0.3 parts by weight surfactant 20 parts by weight denatured ethanol 400 parts by weight water

Comparative Example 3 An ink jet recording medium was produced in the same manner as in Example 1 except that the coating composition 1 was replaced by the coating composition 8 having the following composition. This was used as a sample of Comparative Example 3.

Coating composition 8 : 60 parts by weight of silica (trade name: "FINESEAL X37B" manufactured by Tokuyama Corporation) 300 parts by weight of polyvinyl alcohol (trade name: "Gothenal T-330" manufactured by Nippon Synthetic Chemical Industry Co., Ltd.), 10 % Aqueous solution) -Cationic polymer 20 parts by weight (trade name "PAL-2" Senka Co., Ltd., 20% aqueous solution) -Dipotassium hydrogen citrate (Kanto Chemical Co., Inc.) 3 parts by weight Water 200 parts by weight

Comparative Example 4 An inkjet recording medium was produced in the same manner as in Example 1 except that the coating composition 1 was replaced with the coating composition 9 having the following composition. This was used as a sample of Comparative Example 4.

Coating composition 9 60 parts by weight of silica (trade name "Fineseal X37B" manufactured by Tokuyama Corporation) 300 parts by weight of polyvinyl alcohol (trade name "Gothenal T-330" manufactured by Nippon Synthetic Chemical Industry Co., Ltd.) 10 % Aqueous solution) -Cationic polymer 20 parts by weight (trade name "PAL-2" manufactured by Senka Co., Ltd., 20% aqueous solution) -Water 200 parts by weight

Comparative Example 5 An ink jet recording medium was produced in the same manner as in Example 6 except that the coating composition 6 was replaced with the coating composition 10 having the following composition. This was used as a sample of Comparative Example 5.

Coating composition 10 : 100 parts by weight of vapor phase silica (trade name "Aerosil 300" manufactured by Nippon Aerosil Co., Ltd.) 200 parts by weight of polyvinyl alcohol (trade name "Gothenal T-330" manufactured by Nippon Synthetic Chemical Co., Ltd.) Manufactured by 10% aqueous solution) 4 parts by weight of cationic polymer (trade name "Charol DC902P" manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) 4 parts by weight of basic polyaluminum hydroxide (trade name "Purachem WT" RIKEN Green Co., Ltd.) 10% aqueous solution) ・ Boric acid (Kanto Chemical Co., Inc.) 3 parts by weight ・ Surfactant 0.3 parts by weight ・ Water 700 parts by weight

Test Example The film surface pH and the porosity of the ink receiving layer in each of the ink jet recording media thus obtained were measured. The film surface pH is A of the surface pH test method for paper and paperboard specified by the Japan Pulp and Paper Technology Association.
Method (coating method) [J. TAPPI No. 6] and the porosity is determined according to J. TAPPI No. It was measured according to 48-85. The heat resistance of each inkjet recording medium was evaluated by the following method. For each inkjet recording medium, an ink jet printer PM-800C manufactured by Seiko Epson was used to obtain a magenta density of 1.0.
(OD value) solid pattern and black density 1.0 (O
A solid pattern (D value) was printed to obtain recorded matter, and the light resistance, gas resistance and ozone resistance of these recorded matter were evaluated by the following methods. The above evaluation results are shown in Table 1 below.

(Heat Resistance Evaluation Method) The ink jet recording medium was left for 200 hours in an environment of 80 ° C. and 60% RH. The color difference dE * ab of the base (white background) part of the inkjet recording medium before and after leaving was determined (JIS Z8.
730). The smaller this value is, the better the heat resistance is.

(Evaluation Method of Light Resistance) With respect to the recorded matter,
Using a xenon weatherometer Ci35A (manufactured by Atlas Electric Device Co.), wavelength 340 nm, radiant energy 0.25 W / m ² , black panel temperature 6
A light exposure treatment of 45 kJ / m ² was performed under the conditions of 3 ° C. and 50% RH. Using a Gretag densitometer (manufactured by Gretag), the light reflection densities of the recorded matter before and after the light exposure treatment were obtained, and the optical density residual ratio was obtained by the following formula. The larger this value is, the better the light resistance is. Optical density residual rate (%) = {(light reflection density after light exposure treatment) / (light reflection density before light exposure treatment)} × 100

(Evaluation Method of Gas Resistance) The recorded matter was stuck on the wall of the office and left for one month. The difference dE * ab between the chromaticity of the image after standing and the chromaticity of the image immediately after printing was determined (in accordance with JIS Z8730). The smaller this value is, the better the gas resistance is.

(Evaluation Method for Ozone Resistance)
The sample was placed in a light-shielded tank kept at an ozone concentration of 10 ppm and left for 120 minutes to obtain a color difference dE of the recorded matter before and after the introduction.
* Ab was determined (in accordance with JIS Z8730). The smaller this value is, the better the ozone resistance is.

[0063]

[Table 1]

As is clear from the results shown in Table 1, the ink jet recording media of Examples 1 to 6 containing the "compound having a phenolic hydroxyl group, a salt consisting of a weak acid and a strong base" are the same as Comparative Examples 1 to 1. 5 has excellent heat resistance, is less likely to cause yellowing of the substrate, and has light resistance and gas resistance of recorded images.
A recorded matter having excellent ozone resistance and capable of being stored for a long period of time can be provided. As in Comparative Examples 1 and 2, the use of only a compound having a phenolic hydroxyl group (phenolic antioxidant) is effective in improving the light resistance, gas resistance and ozone resistance of a recorded image, but The heat resistance, which is an indicator of yellowing, deteriorates. Further, as in Comparative Example 3, the use of only a salt consisting of a weak acid and a strong base is not effective in improving the storability of a recorded image. In Comparative Examples 4 and 5, neither the phenolic antioxidant nor the salt composed of the weak acid and the strong base was used, and the yellowing of the substrate due to the phenolic antioxidant was not observed. Poor image storage.

[0065]

According to the present invention, it is possible to provide a recorded matter which is unlikely to undergo discoloration or fading of a recorded image for a long period of time and which can be stored for a long period of time.

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Claims (10)

[Claims] 1. An inkjet recording medium having an ink receiving layer on a substrate, wherein the ink receiving layer contains a compound having a phenolic hydroxyl group and a salt consisting of a weak acid and a strong base. 2. The compound having a phenolic hydroxyl group and a salt composed of a weak acid and a strong base is (A) a compound having a phenolic hydroxyl group and (B) a compound having a salt composed of a weak acid and a strong base. Item 2. The inkjet recording medium according to item 1. 3. The ink jet recording medium according to claim 2, wherein the compound (A) having a phenolic hydroxyl group is a monohydric phenol or a derivative thereof. 4. The ink jet recording medium according to claim 2, wherein the compound (B) having a salt of a weak acid and a strong base is an alkali metal salt of a carboxylic acid. 5. The inkjet recording medium according to claim 2, wherein the compound (B) having a salt of a weak acid and a strong base is a lithium salt or a sodium salt of a carboxylic acid. 6. The ink jet recording medium according to claim 1, wherein the ink receiving layer contains an inorganic pigment, a binder resin and a dye fixing agent. 7. The ink jet recording medium according to claim 6, wherein the inorganic pigment is amorphous silica. 8. The ink jet recording medium according to claim 6, wherein the dye fixing agent is a cationic polymer. 9. The ink receiving layer has a porosity of 30 to 80.
%, The inkjet recording medium according to claim 1. 10. The ink jet recording medium according to claim 1, wherein the base material is a polyolefin resin-coated paper.