JPH08150773A - Ink jet recording sheet - Google Patents

Abstract

PURPOSE: To obtain an ink j et recording sheet with high printing density of recorded images and letters, excellent ink-absorbing properties and remarkably reduced yellowing. CONSTITUTION: An ink jet recording sheet wherein an ink receiving layer is provided on a substrate and an inorg. pigment with a BET specific area of at least 100m<2> /g, at least one water-soluble anti-oxidizing agent selected from ascorbic acid, erysorbic acid or their deriv. and an adhesive are incorporated in parallel in the ink receiving layer, is provided.

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 for recording with ink, and in particular, it has a high print density of images and characters recorded on the ink jet recording sheet and is excellent in ink absorbability. The present invention relates to an inkjet recording sheet in which the yellowing of the white paper portion, which is a drawback of the conventional coated type inkjet recording sheet, is remarkably reduced.

[0002]

2. Description of the Related Art The ink jet recording system is a system in which minute droplets of ink are ejected by various operating principles and adhered to a recording sheet such as paper to record images, characters, etc., but high speed and low noise. , Easy to multicolor, great flexibility of recording pattern, no need for development-fixing,
As a recording device for various figures and color images including kanji, it is rapidly spreading in various applications. Furthermore, the image formed by the multicolor ink jet system is
It is possible to obtain a comparable record. In addition, in applications requiring a small number of copies, it is being widely applied to the field of full-color image recording because it is cheaper than the photographic technique.

As a recording sheet used in this ink jet recording system, efforts have been made from the viewpoint of the apparatus and the ink composition in order to use high-quality paper or coated paper which is used for ordinary printing and writing. However, as the performance of inkjet recording apparatuses has been improved and the applications have been expanded, such as high-speed, high-definition or full-color apparatus, the recording sheets are required to have higher characteristics. That is, as the recording sheet, the density of print dots is high, the color tone is bright and vivid, the ink does not flow out or bleed even when the print dots overlap due to fast ink absorption, and the print dots The lateral spread of the ink does not become larger than necessary, the shape of the ink dots is close to a perfect circle, the periphery is smooth and does not blur, the whiteness of the recording sheet is high, and the contrast with the ink dots is large, etc. Needs to be satisfied.

Conventionally, in order to satisfy these conditions,
It has been proposed to apply various inorganic pigments to the paper surface together with an adhesive, if necessary, or to add them internally.
Use of synthetic amorphous silica and / or its salt as an inorganic pigment (JP-A-57-157786) and inclusion of a porous cationic hydrated aluminum oxide (JP-A-60-232990). However, among them, as described in JP-A-60-204390 and JP-A-2-198889, among them, synthetic amorphous silica and cation having a large BET specific surface area are known. A recording sheet containing a cationic hydrated aluminum oxide which is a hydrophilic colloid particle has an advantage that it has a particularly high printing density and is excellent in ink absorption and color development.

However, such a recording sheet containing an inorganic pigment having a high specific surface area is stored in a file made of polyethylene, polypropylene, vinyl chloride resin or the like, or is contacted with a tape, a glue, a platen rubber roll of a printer or the like for a long time. If this is done, there is a problem in that the white portion of the recording sheet turns yellow and the appearance is significantly impaired. In addition, in order to improve the water resistance of printed images and characters, such inkjet recording sheets are usually
A cationic dye fixing agent is added together with an inorganic pigment,
When such a cationic dye fixing agent is added, the cause is not clear, but it is known that the yellowing of the white paper portion of the recording sheet is further aggravated.

The reason why the white paper portion of the ink jet recording sheet turns yellow in this way is that the ratio of the antioxidant contained in the file such as polyethylene or polypropylene, the tape adhesive, the glue, the rubber or the like to form the ink receiving layer is high. It is considered that this is because the inorganic pigment having a surface area is volatilized and adsorbed, and is oxidized on the recording sheet. Many polypropylenes, polyethylenes, and the like are kneaded with an antioxidant having a phenol group in the molecule, such as butylhydroxytoluene (hereinafter abbreviated as BHT), and these phenolic antioxidants are oxidized to give quinone. It is well known that the structure makes it yellow.

In order to avoid such a problem, in JP-A-1-115677, a recording sheet having both a synthetic silica having a specific surface area of 100 m ² / g or more by a BET method and a thioether antioxidant is disclosed in JP-A-1-115677. JP-A 1-218882 discloses a recording sheet in which the surface coat layer contains a synthetic amorphous silica having a BET specific surface area of 10 to ²⁰⁰ m ² / g, which is surface-treated with an aluminum compound, and JP-A-5-221115 discloses an ink receiving layer. As described above, a recording sheet containing starch particles or modified starch particles thereof and ethylene vinyl acetate copolymer resin or a cationic dye fixing agent in combination is required for the inkjet recording sheet as described above. It satisfies various characteristics and suppresses the yellowing problem of the blank part of the recording sheet.

However, with the recording sheet as described above, while satisfying various characteristics required of the ink jet recording sheet such as sufficient print density and ink absorbability, the yellowing of the white paper portion of the recording sheet is completely eliminated. It was difficult to avoid.

[0009]

SUMMARY OF THE INVENTION An object of the present invention is to further improve the conventional technique in the above technical field. In particular, in the present invention, a white paper of an inkjet recording sheet containing an inorganic pigment having a high specific surface area, which gives a high print density, excellent ink absorbability and color development, but easily causes yellowing of a white paper portion when stored in a file etc. This is to prevent yellowing of the parts.

[0010]

Means for Solving the Problems As a result of intensive studies for solving the above problems, the present inventors have found that ascorbic acid or erythorbic acid is contained in an ink receiving layer composed of an inorganic pigment having a high specific surface area and an adhesive. , Or a coat type inkjet recording sheet containing at least one water-soluble antioxidant selected from derivatives thereof,
The inventors have found that the object of the present invention is satisfied, and have invented the inkjet recording sheet of the present invention.

That is, the ink jet recording sheet of the present invention is an ink jet recording sheet in which an ink receiving layer is provided on a support, and the ink receiving layer composition mainly comprises an inorganic pigment having a BET specific surface area of 100 m ² / g or more and an adhesive. An ink jet recording sheet comprising an agent and containing at least one water-soluble antioxidant selected from ascorbic acid, erythorbic acid or derivatives thereof in the ink receiving layer.

Further, preferably, the ink jet recording sheet is characterized in that the water-soluble antioxidant is erythorbic acid or sodium erythorbate.

The water-soluble antioxidant is added in an amount of 0.5 to 20% by weight based on 100 parts by weight of the inorganic pigment in the ink receiving layer.
It is preferably 0 part by weight.

The inorganic pigment is preferably at least one kind selected from synthetic amorphous silica and cationic colloidal particles.

An ink jet recording sheet is characterized in that the ink receiving layer composition contains a cationic dye fixing agent.

The ink jet recording sheet of the present invention will be described in detail below. Examples of ascorbic acid or erythorbic acid or derivatives thereof in the present invention include ascorbic acid, erythorbic acid, ascorbic acid-5-o-pelargonyl, erythorbic acid-5-o-pelargonyl, and ascorbic acid-5-o-. Palmitaire,
Erythorbic acid-5-o-palmitate, ascorbic acid-2,5-o-dipalmitate, erythorbic acid-
2,5-o-dipalmitate, ascorbic acid-6-o
-Stearyl, erythorbate-6-o-stearyl,
Ascorbic acid-3-o-nicotinyl, erythorbic acid-3-o-nicotinyl, 6-o-decanoyl ascorbate, 6-o-decanoyl erythorbate, 6-o-lauryl ascorbate, erythorbic acid-6- o
-Lauryl, ascorbic acid-6-o-myristyl,
Erythorbic acid-6-o-myristyl, sodium ascorbate, sodium erythorbate, potassium ascorbate, potassium erythorbate, calcium ascorbate, calcium erythorbate, and the like can be used at least one or more, and are water-soluble. , Phenol-based oxidation that is easily adsorbed on the inorganic pigment of the inkjet recording sheet prepared by coating and drying it on the support as an aqueous coating solution, and is thought to be the cause of yellowing of the white paper part. Oxidation of the inhibitor can be effectively prevented.

In order to investigate the degree of yellowing of the blank portion of the ink jet recording sheet, the present inventors have examined the BHT dimer (4,4'-methylenebis-2, 6-di-t-butylphenol) alcohol (ethanol, isopropyl alcohol, etc.) 1
% Solution as 0.5% solid content on the ink recording sheet.
Spotted to g / m ² and air-dried, 20 ℃, 65
It is left for 3 days under the condition of% RH, and L ^* before and after the leaving ^.
a ^* b ^* (color specification method based on CIE) is a color difference meter (C
R100: manufactured by Minolta). Then, the degree of yellowing of the white paper portion was evaluated by the difference in b ^* before and after the treatment (Δb ^* ). It should be noted that the smaller this value is, the smaller the yellowing change is, and Δb ^* is preferably 15 or less, and 10 or less does not pose a problem in practical use and is particularly preferable. The tendency of this measurement result almost coincided with the degree of yellowing of the white paper portion that occurred when actually storing it in a file or the like.

In the ink jet recording sheet of the present invention, the Δb ^* value measured by the above method is 15 or less, and the yellowing of the white paper portion of the recording sheet can be remarkably suppressed. When the ink receiving layer composition does not contain at least one or more water-soluble antioxidants selected from ascorbic acid derivatives or erythorbic acid derivatives and contains only an inorganic pigment and an adhesive, the white paper portion of the recording sheet easily turns yellow, The Δb ^* value measured by the above method exceeds 15, which is not preferable.

Further, the present inventors have found that among the water-soluble antioxidants, the use of erythorbic acid or sodium erythorbate further enhances the effect of preventing yellowing of the white paper portion.

Although the reason for this is not clear, in general, erythorbic acid and sodium erythorbate have a higher antioxidant effect than ascorbic acid and other water-soluble antioxidants, and therefore the same applies to the present invention. It is considered that the effect of.

The water-soluble antioxidant in the present invention is preferably 0.1 to 2 per 100 parts by weight of the inorganic pigment.
0.0 solid part by weight, more preferably 0.1 to 1
0.0 solid part by weight. If the addition amount is less than 0.1 solid parts by weight, a sufficient yellowing preventing effect cannot be obtained, and if the addition amount exceeds 20.0 solid parts by weight, the yellowing preventing effect is not improved. It may adversely affect other characteristics (print density, ink absorbency, etc.).

Preferred as the inorganic pigment contained in the ink receiving layer of the ink jet recording sheet of the present invention is B.
An inorganic pigment having an ET specific surface area of 100 m ² / g or more, more preferably 100 to 700. By using an inorganic pigment having such a specific surface area, high printing density and excellent ink absorbency can be achieved. If the BET specific surface area of the inorganic pigment is less than 100 m ² / g, sufficient printing density and ink absorbency cannot be obtained, which is not preferable.

As the inorganic pigment in the present invention, one or more known white pigments can be used. For example, light calcium carbonate, heavy calcium carbonate, kaolin, talc, calcium sulfate, barium sulfate, titanium dioxide, zinc oxide, zinc sulfide, zinc carbonate, satin white, aluminum silicate, diatomaceous earth, calcium silicate, magnesium silicate, synthetic non- Examples thereof include crystalline silica, colloidal silica, colloidal alumina, pseudo-boehmite, aluminum hydroxide, alumina, lithopone, zeolite, hydrohalloysite, magnesium carbonate, magnesium hydroxide and the like.

In the present invention, among the above-mentioned inorganic pigments, particularly when at least one kind of inorganic pigment selected from synthetic amorphous silica or cationic colloid particles is used, the print density and ink absorbency are further increased. Therefore, it is preferable.

The term "cationic colloidal particles" as used in the present invention means particles that are suspended and dispersed in water to form a colloidal shape, and the surfaces of the particles are positively charged.
Examples thereof include alumina sol such as boehmite and pseudo-boehmite, colloidal alumina, and particles obtained by coating the surface of colloidal silica particles with alumina as disclosed in JP-B-47-26959.

In the ink receiving layer of the present invention, a water-soluble dye, which is a dye component of the water-based ink, is added to the recording sheet in order to impart water resistance for suppressing the flow or bleeding of the ink due to the dropping of water or the absorption of moisture. Addition of a cationic dye fixing agent consisting of a secondary amine, a tertiary amine, and a quaternary ammonium salt that forms an insoluble salt with a sulfonic acid group, a carboxyl group, an amino group in a water-soluble direct dye or a water-soluble acid dye Is possible. Usually, when a cationic dye fixing agent is added to the ink receiving layer, the yellowing of the white paper portion during storage in a file is aggravated, but in the present invention, at least one or more selected from an ascorbic acid derivative or an erythorbic acid derivative. Due to the yellowing-preventing effect of the water-soluble antioxidant, the yellowing of white paper is suppressed.

The ink receiving layer in the present invention may contain an adhesive together with the inorganic pigment and the phosphorus-based antioxidant in order to enhance the adhesive strength between the inorganic pigments and between the ink receiving layer and the support. Examples of the adhesive include polyvinyl alcohol, silanol-modified polyvinyl alcohol, vinyl acetate, oxidized starch, etherified starch, cellulose derivatives such as carboxymethyl cellulose and hydroxyethyl cellulose, casein, gelatin, soybean protein, silyl-modified polyvinyl alcohol and the like; maleic anhydride. Conjugated diene copolymer latex such as acid resin, styrene-butadiene copolymer, methyl methacrylate-butadiene copolymer; polymer or copolymer of acrylic acid ester and methacrylic acid ester, polymer of acrylic acid and methacrylic acid Or an acrylic polymer latex such as a copolymer; a vinyl polymer latex such as an ethylene vinyl acetate copolymer; or a functional group-modified polymer with a functional group-containing monomer such as a carboxyl group of these various polymers Tex: Water-based adhesive such as thermosetting synthetic resin based on melamine resin and urea resin; Synthetic resin based adhesive such as polymethylmethacrylate, polyurethane resin, unsaturated polyester resin, vinyl chloride-vinyl acetate copolymer, polyvinyl butyral and alkyd resin One or more agents can be used. In addition, the use of known natural or synthetic resin adhesives is not particularly limited.

The amount of the adhesive compounded is 100% of inorganic pigment.
It is from 3 to 70 solid parts by weight, preferably from 5 to 50 solid parts by weight, based on the solid parts by weight. When it is less than 3 solid parts by weight, the coating strength of the ink receiving layer is insufficient and exceeds 70 solid parts by weight. In some cases, depending on the type of inkjet recording device, the ink absorbency may be reduced.

Further, as other additives, pigment dispersants, thickeners, fluidity improvers, defoamers, defoamers, mold release agents,
A foaming agent, a penetrating agent, a coloring dye, a coloring pigment, a fluorescent whitening agent, an ultraviolet absorber, an antiseptic agent, an anti-bacterial agent, a water resistance agent, a wet paper strength enhancer, a dry paper strength enhancer, etc. may be appropriately blended. it can.

In the present invention, the surface of the ink receiving layer may be provided with a coating layer (hereinafter, referred to as a gloss developing layer) which imparts the gloss of a commercially available art coated paper.

The method for providing the ink receiving layer and the gloss developing layer in the present invention may be either an on-machine coater or an off-machine coater. For example, conventionally known various devices such as an air knife coater, a curtain coater, a die coater, a blade coater, a gate roll coater, a bar coater, a rod coater, a roll coater, a bill blade coater, a short dwell blade coater, and a size press are on-machine or Can be used off-machine. Further, after coating, it is also possible to finish using a calendar device such as a machine calendar, a TG calendar, a super calendar, and a soft calendar.

By providing the gloss-developing layer by the cast coating method, it is possible to obtain a gloss feeling comparable to that of commercially available cast-coated paper.

The coating amount of the ink receiving layer in the present invention is not particularly limited, but is preferably 1 to 30 g / m ² . When the coating amount is less than 1 g / m ^2, it is not preferable because sufficient printing density and ink absorbency cannot be obtained, and when the coating amount exceeds 30 g / m ² , curling property of the recording sheet is deteriorated, which is not preferable. . In addition, the ink receiving layer can be applied with a certain coating amount divided into several times, and in the case of imparting gloss, the gloss is improved as compared with applying the coating amount at once. .

As a method of coating the phosphorus antioxidant solution or its emulsion on the ink receiving layer in the present invention, either an on-machine coater or an off-machine coater may be used. For example, a conventionally known air knife coater,
Curtain coater, die coater, blade coater,
Various devices such as a gate roll coater, a bar coater, a rod coater, a roll coater, a bill blade coater, a short dwell blade coater, and a size press can be used on machine or off machine.
Further, a sprayer using compressed air may be used.
Further, after coating, it is also possible to finish using a calendar device such as a machine calendar, a TG calendar, a super calendar, and a soft calendar.

The support used in the present invention is LB
Chemical pulp such as KP, NBKP, GP, PGW, RM
P, TMP, CTMP, CMP, mechanical pulp such as CGP, wood pulp such as waste paper pulp such as DIP, and conventionally known pigments as a main component, and a binder and a sizing agent, a fixing agent, a yield improving agent, a cationizing agent, Starch, polyvinyl alcohol, and base paper manufactured by various devices such as fourdrinier paper machine, cylinder paper machine, twin wire paper machine, etc. A base paper provided with a size press or an anchor coat layer, and coated paper such as art paper, coated paper, cast coated paper provided with a coated layer thereon are also included. Such base paper and coated paper may be provided with the coating layer according to the present invention as they are,
For the purpose of controlling flattening, machine calendar,
You may use calendar devices, such as a TG calendar and a soft calendar. The basis weight of the support is usually 40 to 300 g / m ² , but is not particularly limited.

A back coat layer may be coated on the opposite surface of the ink receiving layer sandwiching the support in order to impart curl aptitude.
Tabular pigments and hydrohaloysite are preferred.

The ink referred to in the present invention means the following colorants,
A recording liquid composed of a liquid medium and other additives. Examples of the colorant include water-soluble dyes such as direct dyes, acid dyes, basic dyes, reactive dyes and food dyes.

As the ink solvent, water and various water-soluble organic solvents such as methyl alcohol, ethyl alcohol, n-propyl alcohol, isopropyl alcohol, n-butyl alcohol, sec-butyl alcohol,
C1-C4 alkyl alcohols such as tert-butyl alcohol and isobutyl alcohol; amides such as dimethylformamide and dimethylacetamide; acetone,
Ketones or ketone alcohols such as diacetone alcohol; ethers such as tetrahydrofuran and dioxane;
Polyalkylene glycols such as polyethylene glycol and polypropylene glycol; ethylene glycol,
Alkylene glycols having 2 to 6 alkylene groups such as propylene glycol, butylene glycol, triethylene glycol, 1,2,6-hexanetriol, thiodiglycol, hexylene glycol, diethylene glycol; glycerin, ethylene glycol methyl ether, diethylene glycol Examples thereof include lower alkyl ethers of polyhydric alcohols such as methyl (or ethyl) ether and triethylene glycol monomethyl ether. Among these many water-soluble organic solvents, polyhydric alcohols such as diethylene glycol and lower alkyl ethers of polyhydric alcohols such as triethylene glycol monomethyl ether and triethylene glycol monoethyl ether are preferable. Other additives include, for example, P
Examples include H regulators, sequestering agents, antioxidants, antifungal agents, viscosity regulators, surface tension regulators, wetting agents, surfactants, and rust inhibitors.

The ink jet recording sheet according to the present invention is not limited to use as an ink jet recording sheet, and may be used as any recording sheet using a liquid ink during recording. For example, an ink sheet coated with a heat-fusible ink containing a heat-fusible substance, a dye or pigment as a main component on a thin support such as a resin film, high-density paper, or synthetic paper is heated from the back surface of the ink sheet, An image-receiving sheet for thermal transfer recording that melts and transfers ink, an inkjet recording sheet that heat-melts a heat-melting ink to form fine droplets, and flight recording, an inkjet recording sheet that uses an ink in which an oil-soluble dye is dissolved, Examples thereof include an image receiving sheet corresponding to a light and pressure sensitive donor sheet using microcapsules containing a polymerizable monomer and colorless or colored dyes and pigments.

The common feature of the above recording sheets is that the ink is in a liquid state at the time of recording. Liquid ink cures,
Before solidification or fixing, the ink permeates or spreads in the depth direction or the horizontal direction of the ink receiving layer of the recording sheet. The various recording sheets described above require absorptivity according to their respective systems, and the inkjet recording sheet of the present invention may be used as the various recording sheets described above.

Further, the ink jet recording sheet of the present invention may be used as a recording sheet for fixing toner by heat in the electrophotographic recording system which is widely used in copying machines, printers and the like. Further, a pressure-sensitive adhesive layer is coated on the opposite surface of the ink-receiving layer sandwiching the support,
It can also be applied to label applications.

[0042]

The ink jet recording sheet of the present invention is an ink jet recording sheet having an ink receiving layer provided on a support, and the ink receiving layer composition is mainly composed of an inorganic pigment having a BET specific surface area of 100 m ² / g or more and an adhesive. And an at least one water-soluble antioxidant selected from ascorbic acid, erythorbic acid, or derivatives thereof in the ink-receiving layer. The high print density of the images and characters recorded on, while maintaining the characteristics of excellent ink absorption, was a drawback of the conventional coated paper type inkjet recording sheet,
The present invention relates to an inkjet recording sheet in which yellowing of a white paper portion is significantly reduced.

[0043]

EXAMPLES Examples of the present invention will be described below, but the present invention is not limited to these examples.
In addition, "parts" and "%" shown in the examples represent parts by weight and% by weight, unless otherwise specified.

Example 1 The support was prepared by adding light calcium carbonate / heavy calcium carbonate / talc to 100 parts of wood pulp composed of 80 parts of LBKP (freeness of 400 mlcsf) and 20 parts of NBKP (freeness of 480 mlcsf). 20 parts of pigment having a ratio of 10/10/10, 0.10 parts of commercial alkyl ketene dimer,
After preparing 0.03 part of a commercially available cationic acrylamide, 1.0 part of a commercially available cationized starch and 0.5 part of a sulfuric acid band, papermaking was carried out with a Fourdrinier paper machine to obtain a support having a basis weight of 90 g / m ² .

The ink receiving layer was coated on the surface of the support.
The coating composition of the ink receiving layer has a BET specific surface area of 270 m ²
/ g of synthetic amorphous silica (FINESEAL X-37B: manufactured by Tokuyama Soda), 100 parts, polyvinyl alcohol (PVA1
17: Kuraray) 30 parts, cationic dye fixing agent (Sumireds resin 1001: Sumitomo Chemical Co., Ltd.) 20 parts, erythorbic acid (Pfizer) 5 parts
This coating liquid was dried with an air knife coater to a dry coating amount of 8
The inkjet recording sheet of Example 1 was prepared by coating and drying the support so as to be g / m ² .

Example 2 An ink jet recording sheet of Example 2 was prepared in the same manner as in Example 1 except that erythorbic acid of Example 1 was changed to sodium ascorbate (manufactured by Pfizer) as a coating composition for the ink receiving layer. It was made.

Example 3 The procedure of Example 3 was repeated except that the erythorbic acid of Example 1 was changed to sodium erythorbate (Elbit N: manufactured by Fujisawa Pharmaceutical Co., Ltd.) as a coating composition for the ink receiving layer. An inkjet recording sheet was prepared.

Example 4 A support was obtained in the same manner as in Example 1. The ink receiving layer was coated on the surface of the support. The coating composition for the ink receiving layer was 100 parts of synthetic amorphous silica (Fineseal X-37B: manufactured by Tokuyama Soda), polyvinyl alcohol (PVA117:
Kuraray) 30 parts, colloidal silica (Snowtex-O: Nissan Kagaku) 30 parts, cationic dye fixing agent (SUMIREZ Resin 1001: Sumitomo Chemical) 20 parts, sodium erythorbate (Elbit N: Fujisawa Yakuhin) 5 These are prepared as a part, and this coating solution is applied to a support by an air knife coater so that the dry coating amount is 8 g / m ^2.
Dried.

Then, a gloss developing layer was applied to the surface of the ink receiving layer. As the colloidal particles, the coating composition for the gloss-developing layer contains 100 organic pigments (L8999: manufactured by Asahi Kasei Co., Ltd.) containing polystyrene having a mean particle size of 200 nm as a main component.
Parts, 30 parts of an acrylic latex (SX984A1: made by Japan Synthetic Rubber) having an average particle size of 50 nm as a synthetic polymer latex, 1 part of commercially available potassium oleate as a release agent, and a solid content concentration of 30%, These were prepared. Then, this coating liquid was applied to the ink receiving layer surface by a cast method by a direct method so that the dry coating amount was 3 g / m ² by a roll coater to prepare an inkjet recording sheet of Example 4.

Example 5 As a coating composition for the ink-receiving layer, the sodium erythorbate of Example 3 was impregnated into the ink-receiving layer so as to be 0.45 solid parts by weight based on 100 parts by weight of the inorganic pigment. An inkjet recording sheet of Example 5 was produced in the same manner as in Example 3 except that the above was performed.

Example 6 As the coating composition for the ink receiving layer, the sodium erythorbate of Example 3 was impregnated into the ink receiving layer so as to be 22.0 parts by weight based on 100 parts by weight of the inorganic pigment. An inkjet recording sheet of Example 6 was produced in the same manner as in Example 3 except that the above was performed.

Example 7 In the same manner as in Example 3 except that the synthetic amorphous silica of Example 3 was changed to ultrafine calcium carbonate having a BET specific surface area of 105 m ² / g as a coating composition for the ink receiving layer. Example 7
An inkjet recording sheet of was prepared.

Example 8 As a coating composition for an ink receiving layer, the synthetic amorphous silica of Example 3 was used as a synthetic amorphous silica having a BET specific surface area of 120 m ² / g (Mizukasil NP-8: manufactured by Mizusawa Chemical Co., Ltd.). An ink jet recording sheet of Example 8 was produced in the same manner as in Example 2 except that it was changed.

Example 9 As a coating composition for an ink receiving layer, the synthetic amorphous silica of Example 3 was mixed with synthetic amorphous silica having a BET specific surface area of 380 m ² / g (Mizukasil P-78C, manufactured by Mizusawa Chemical Co., Ltd.). An ink jet recording sheet of Example 9 was produced in the same manner as in Example 3 except that it was changed.

Example 10 As a coating composition for an ink receiving layer, the synthetic amorphous silica of Example 3 was used as a cationic alumina hydrate having a BET specific surface area of 275 m ² / g (Cataloid AS-3: manufactured by Catalysis). An inkjet recording sheet of Example 10 was produced in the same manner as in Example 3 except that the above was changed to.

Example 11 A support was obtained in the same manner as in Example 3. The ink receiving layer was coated on the surface of the support. The coating composition for the ink receiving layer was 100 parts of synthetic amorphous silica (Fineseal X-37B: manufactured by Tokuyama Soda), polyvinyl alcohol (PVA117:
These were prepared as 30 parts of Kuraray) and 5 parts of sodium erythorbate (Elbit N: manufactured by Fujisawa Chemical Co., Ltd.), and this coating solution was dried with an air knife coater to give a dry coating amount of 8 g / m ²
An ink jet recording sheet of Example 11 was prepared by coating and drying the support so that

Comparative Example 1 A support was obtained in the same manner as in Example 1. The ink receiving layer was coated on the surface of the support. The coating composition of the ink receiving layer is B
Commercially available light calcium carbonate with an ET specific surface area of 5 m ² / g 100
Part, polyvinyl alcohol (PVA117: made by Kuraray)
30 parts, cationic dye fixing agent (Sumired's resin 10
(01: manufactured by Sumitomo Chemical Co., Ltd.), using 20 parts of solid content concentration of 15%, these are prepared, and the coating solution is coated on a support with an air knife coater so that the dry coating amount is 8 g / m ^2. -Drying, the inkjet recording sheet of the comparative example 1 was produced.

Comparative Example 2 As a coating composition for the ink receiving layer, a comparison was made except that the calcium carbonate of Comparative Example 1 was changed to synthetic amorphous silica having a BET specific surface area of 40 m ² / g (Mizukasil P527, manufactured by Mizusawa Chemical Co., Ltd.). An inkjet recording sheet of Comparative Example 2 was prepared in the same manner as in Example 1.

Comparative Example 3 As a coating composition for the ink receiving layer, the calcium carbonate of Comparative Example 1 was changed to synthetic amorphous silica having a BET specific surface area of 270 m ² / g (Fineseal X37B: manufactured by Tokuyama Soda). An inkjet recording sheet of Comparative Example 3 was prepared in the same manner as in Comparative Example 1.

Comparative Example 4 A support was obtained in the same manner as in Example 1. The ink receiving layer was coated on the surface of the support. The coating composition for the ink receiving layer was 100 parts of synthetic amorphous silica (Fineseal X-37B: manufactured by Tokuyama Soda), polyvinyl alcohol (PVA117:
(Manufactured by Kuraray Co., Ltd.) were prepared as 30 parts, and the coating liquid was applied to a support by an air knife coater so as to have a dry coating amount of 8 g / m ² and dried to obtain an inkjet recording sheet of Comparative Example 4. It was made.

Comparative Example 5 An antioxidant dispersion A having the following composition was prepared in advance. [Antioxidant Dispersion Liquid A] Butylhydroxytoluene (BHT: Wako Pure Chemical Industries, Ltd.) 10 parts Isopropyl alcohol 90 parts

The support was obtained in the same manner as in Example 1. The ink receiving layer was coated on the surface of the support. The coating composition for the ink receiving layer was 100 parts of synthetic amorphous silica having a BET specific surface area of 270 m ² / g (Fineseal X37B: manufactured by Tokuyama Soda),
Polyvinyl alcohol (PVA117: made by Kuraray) 30
Part, cationic dye fixing agent (Sumireds resin 100
20 parts of Sumitomo Chemical Co., Ltd.) and a solid content of 15% were prepared to prepare a coating solution, and the coating solution was coated on a support with an air knife coater so that the dry coating amount was 8 g / m ^2. Dried. Then, the antioxidant dispersion A prepared in advance was added to the ink receiving layer in an amount of 0.
An inkjet recording sheet of Comparative Example 5 was prepared by coating and impregnating with a roll coater so that the solid content would be 5 parts by weight, and drying.

Comparative Example 6 An antioxidant dispersion B having the following composition was prepared in advance. [Antioxidant Dispersion Liquid B] Dilauryl 3,3'-thiodipropionate (Rasmit LG: manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd.) 10 parts Isopropyl alcohol 90 parts

An ink jet recording sheet of Comparative Example 6 was prepared in the same manner as Comparative Example 5 except that the antioxidant dispersion liquid A of Comparative Example 5 was changed to the antioxidant dispersion liquid B.

Comparative Example 7 A support was obtained in the same manner as in Example 1. The ink receiving layer is
It was applied on the surface of the support. The coating composition of the ink receiving layer,
BET specific surface area 12 surface-treated with aluminum compound
100 parts of 5 m ² / g of synthetic amorphous silica and 30 parts of polyvinyl alcohol (PVA 117: made by Kuraray) were prepared, and the coating liquid was dried with an air knife coater to a dry coating amount of 8 g / m ^2. The ink-jet recording sheet of Comparative Example 7 was prepared by coating and drying the support in this manner.

Comparative Example 8 A support was obtained in the same manner as in Example 1. The ink receiving layer is
It was applied on the surface of the support. The coating composition of the ink receiving layer,
50 parts of synthetic amorphous silica (FINESEAL X-37B: manufactured by Tokuyama Soda), rice starch powder (average particle size 4.9 μm) 50
Part, polyvinyl alcohol (PVA117: made by Kuraray)
An ink jet recording sheet of Comparative Example 8 was prepared by preparing 30 parts of these solutions, and coating and drying the coating solution with an air knife coater to a dry coating amount of 8 g / m ² . .

The evaluation of Examples 1 to 11 and Comparative Examples 1 to 8 was carried out by the method described below, and the results are shown in Table 1.
The measurement and evaluation were performed under the environment specified in JIS P8111.

1) Printing Density A solid pattern was printed with black ink using an inkjet recording device (BJC-820J: manufactured by Canon), and the optical reflection density of the printed portion was measured by Macbeth RD-918.

2) Ink absorbency Using the above-mentioned ink jet recording apparatus, a heavy color rectangular pattern is printed with cyan ink and magenta ink, and the boundary portion between this pattern and the white paper portion is visually observed according to the following criteria. An evaluation was made. A: No distortion is observed at the boundary. B: A slight distortion is seen at the boundary. C: Distortion is seen in all of the boundaries. A or B evaluation is required for good ink absorbency.

3) Yellowing of white paper part [BHT method] BHT dimer (4,4'-methylenebis-
2,6-di-tert-butylphenol) isopyl alcohol 1% solution was spotted on the ink recording sheet so that the solid content was 0.5 g / m ^2, and the temperature was 20 ° C.
Under the condition of 65% RH, L ^* a ^* b ^* (C
A colorimetric color difference meter (CR100:
It was measured by Minolta). Then, the degree of yellowing of the white paper portion was evaluated by the difference in b ^* before and after the treatment (Δb ^* ).
It should be noted that the smaller this value is, the smaller the yellowing change is.

[File Method] A polypropylene plastic file bag (A4 size) containing 1.0% by weight of commercially available BHT was cut into a square of 5 cm × 5 cm in the vicinity of the center of one side, and the coated layer surface had holes. Put it in a file bag so that it hits the file side, leave it for a month in the room, take out the sample, and color the inkjet recording sheet before and after processing L ^* a ^* b ^* (coloring method according to CIE) It was measured with a color difference meter (CR100: manufactured by Minolta). The degree of yellowing of the white paper part depends on the difference in b ^* before and after processing (△
b ^* ), and a smaller value indicates less yellowing.

[0072]

[Table 1]

As is clear from Table 1, Examples 1 to 11
Then, the ink receiving layer composition is mainly composed of an inorganic pigment having a BET specific surface area of 100 m ² / g or more and an adhesive, and at least one selected from an ascorbic acid or erythorbic acid derivative and a metal salt thereof in the ink receiving layer. Since the ink jet recording sheet contains the above water-soluble antioxidant, an ink jet recording sheet having high printing density, excellent ink absorbency, and less yellowing of the white paper portion was obtained.

Among them, as is clear from Examples 1 to 3, erythorbic acid or sodium erythorbate is used among at least one water-soluble antioxidant selected from ascorbic acid or erythorbic acid or derivatives thereof. In that case, an ink jet recording sheet with less yellowing of the white paper was obtained.

Further, as is clear from Examples 3 to 6,
The addition amount of at least one water-soluble antioxidant selected from ascorbic acid, erythorbic acid, or their derivatives is 0.5 with respect to 100 parts by weight of the inorganic pigment.
If it is at least solid parts by weight, the effect of preventing yellowing of the white paper portion will be further enhanced, and if it exceeds 20 parts by weight, the effect of preventing yellowing of the white paper portion will not change. Further, Examples 2 and 7-1
As is clear from 0, when the cationic colloidal particles such as synthetic amorphous silica or cationic alumina hydrate among inorganic pigments are used, and when the BET specific surface area is large, the print density and the ink absorption are increased. An ink jet recording sheet having high properties was obtained.

As is clear from Examples 3 and 11 and Comparative Examples 3 and 4, ascorbic acid or erythorbic acid,
Alternatively, an inkjet recording sheet not containing at least one water-soluble antioxidant selected from derivatives thereof, the addition of a cationic dye fixing agent to obtain water resistance, the yellowing of the white paper portion is considerably deteriorated, In an inkjet recording sheet containing at least one water-soluble antioxidant selected from ascorbic acid or erythorbic acid, or a derivative thereof, a yellow portion of a white paper portion may appear even if a cationic dye fixing agent is added. There was little change.

On the other hand, in the ink jet recording sheets of Comparative Examples 1 and 2, the BET of the inorganic pigment contained in the ink receiving layer was used.
Since the specific surface area was less than 100 m ² / g, the print density and ink absorbency were low. The ink jet recording sheet of Comparative Example 3 used synthetic amorphous silica having a BET specific surface area of 100 m ² / g or more, so that the printing density and the ink absorption were high, but it was selected from ascorbic acid or erythorbic acid or derivatives thereof. Since it did not contain at least one or more water-soluble antioxidants, the yellowing of the white paper part was extremely poor. In the inkjet recording sheet of Comparative Example 5, since the phenolic antioxidant was used as the antioxidant, the yellowing of the white paper portion was further deteriorated.

Further, the ink jet recording sheets of Comparative Examples 6 to 8 contain the thioether type antioxidant, the synthetic silica surface-treated with the aluminum compound, and the starch particles, thereby suppressing the yellowing of the white paper portion. However, the effect of preventing yellowing of the white paper portion was lower than that of the ink jet recording sheet containing at least one water-soluble antioxidant selected from ascorbic acid or erythorbic acid or derivatives thereof in Examples.

[0079]

The present invention mainly uses BET on a support.
By including at least one water-soluble antioxidant selected from ascorbic acid, erythorbic acid, or derivatives thereof in the ink receiving layer, which comprises an inorganic pigment and an adhesive having a specific surface area of 100 m ² / g or more. It is possible to obtain an inkjet recording sheet in which the yellowing of the white paper portion is remarkably reduced while maintaining the characteristics that the printing density of images and characters recorded on the inkjet recording sheet is high and the ink absorbency is excellent.

Claims (5)

[Claims] 1. An ink jet recording sheet having an ink receiving layer provided on a support, wherein the ink receiving layer composition is mainly composed of an inorganic pigment and an adhesive having a BET specific surface area of 100 m ² / g or more, and the ink receiving layer. An ink jet recording sheet, characterized in that the layer contains at least one water-soluble antioxidant selected from ascorbic acid, erythorbic acid, or derivatives thereof. 2. The ink jet recording sheet according to claim 1, wherein the water-soluble antioxidant is erythorbic acid or sodium erythorbate. 3. The water-soluble antioxidant is 0.5 to 20.0 solid parts by weight based on 100 solid parts by weight of the inorganic pigment in the ink receiving layer. Inkjet recording sheet. 4. The inkjet recording sheet according to claim 1, wherein the inorganic pigment is at least one selected from synthetic amorphous silica and cationic colloid particles. 5. The ink-receiving layer composition contains a cationic dye fixing agent, which is characterized in that
The inkjet recording sheet according to any one of 1.