JPH09248958A - Ink-jet recording paper and recording method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide ink-jet recording paper which is characterized by its high image density even in a recording method using a high resolution ink-jet printer, no bleeding of images such as characters, good water resistance to prevent ink elution, and almost no powder falling and a recording method. SOLUTION: In an ink-jet recording paper in which a coating layer containing pigment is formed on base paper consisting mainly of wood pulp, the coating layer is formed by applying coating liquid containing 20-40 pts.wt. of polyvinyl alcohol and/or silanol-modified polyvinyl alcohol and 40-90 pts.wt. of polyamide- polyamine epichlorohydrin per 100 pts.wt. of synthetic amorphous silica. Besides, the coating liquid additionally contains 5 pts.wt. or more of dialkyl sulfosuccinic acid per 100 pts.wt. of synthetic amorphous silica. Using the ink-jet recording paper, a recording image is made by an ink-jet printer of 180-720 DIP resolution.

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 paper and a recording method, and in particular, an ink jet recording paper having a high image density, no bleeding of images such as characters, good water resistance, and very little powder falling off. And a recording method using the same.

[0002]

2. Description of the Related Art The ink jet recording system has advantages such as easy multi-color recording, relatively high recording speed, and recording of large plates. On the other hand, with regard to nozzle clogging and maintenance, which have traditionally been a problem, improvements have been made from both the ink and device sides.
At present, it is widely used in various fields such as various printers, facsimiles, computer terminals, etc., and is rapidly spreading.

In the ink jet recording system, an aqueous ink is usually used from the viewpoint of safety and hygiene, and it is necessary that the ink adhering to the ink jet recording paper be rapidly absorbed. That is, in the case of a color inkjet process using a plurality of ink nozzles,
The ink droplet ejected first needs to be absorbed on the paper surface before the next ink droplet is ejected. From this point, the ink jet recording paper is required to have high ink droplet absorbability. ing.

[0004]

However, in order to obtain a clear image having a high density, the color former in the ink is stopped on the surface of the ink jet recording paper and only the vehicle such as water or solvent is allowed to penetrate into the paper. Is desired. From such a point of view, as the support, papers having adjusted bulk height, air permeability, sizing degree, etc. are also used, but these papers still have an irregular spreading of ink droplets on the paper surface. Ink flow occurs and the color density tends to decrease. Further, if the water resistance of the inkjet recording paper is low, the dye in the ink recording liquid is eluted from the recording paper printed during storage of the printing paper, and the image quality of the printed image tends to be unclear. Further, the conventional inkjet recording paper has a problem that bleeding of characters and the like is likely to occur, and powder is removed due to abrasion of the surface of the inkjet recording paper due to a thermal head, thereby reducing the commercial value of the inkjet recording paper. Further, in recent years, inkjet printers having higher resolution have been used, and there is a demand for inkjet recording papers that do not cause the above problems for such inkjet printers.

An object of the present invention is to provide an ink jet recording paper which has a high color density even for an ink jet printer having a high resolution, has no bleeding of images such as characters, has good water resistance, and has very little powder falling off. It is to provide a recording method using.

[0006]

The above objects of the present invention are as follows: (1) In an ink jet recording paper in which a coating layer containing a pigment is provided on a base paper mainly composed of wood pulp, the coating layer is a synthetic From a coating solution containing 100 parts by weight of crystalline silica, containing 20 parts by weight or more and less than 40 parts by weight of polyvinyl alcohol and / or silanol-modified polyvinyl alcohol, and 40 to 90 parts by weight of polyamide polyamine epichlorohydrin. And an ink jet recording sheet. Further, the above-mentioned object of the present invention is achieved by an inkjet recording paper recording method characterized in that a recorded image is recorded by an inkjet printer having a resolution of 180 to 720 DPI using the inkjet recording paper of (1).

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION In the present invention, the base paper mainly composed of wood pulp is mainly composed of wood pulp such as LBKP and NBPK, and synthetic pulp, synthetic fiber and the like are mixed as necessary. Good. As the freeness after beating,
250 to 450 cc (C.S.F.) is preferable.

[0008] Clay, talc, TiO ₂ , CaCO ₃ , BaSO _4, etc. can be added to the wood pulp as a filler, and these fillers can be added to the pulp at 0%.
-30 parts by weight can be added. In addition to the above-mentioned filler in the wood pulp, if necessary, a sizing agent, paper strength agent,
A fixing agent or the like can be optionally added. Examples of the sizing agent include rosin, alkenyl succinate, stearate, alkyl ketene dimer, and alkenyl succinic anhydride. Examples of the paper strength agent include starch, gelatin, CMC, polyacrylamide, and the like, and examples of the fixing agent include aluminum sulfate, aluminum chloride, polyamide polyamine epichlorohydrin, and the like.

The basis weight of the base paper is 30 to 250 g / m ² , preferably 5 to 150 g / m ² , and the thickness is 30 to 25.
It is 0 μm, preferably 50 to 150 μm. The whiteness (hunter) of the base paper is preferably 70% or more, and the stiffness (Taber) is preferably 1 to 29 g. Water absorption of base paper is preferably a 10 to 30 g / m ² in JIS-P-8140, when less than 10 g / m ^2, the ink flow tends to occur, when it exceeds 30 g / m ^2, blank areas It tends to occur, which is not preferable.

The coating liquid applied to the base paper is polyvinyl alcohol and / or silanol-modified polyvinyl alcohol in an amount of 20 parts by weight or more and less than 40 parts by weight, and polyamide polyamine epichlorohydrin per 100 parts by weight of synthetic amorphous silica. 40 to 90 parts by weight.

The synthetic amorphous silica used in the present invention is
Both anhydrous silicic acid obtained by the dry production method and hydrous silicic acid obtained by the wet production method can be used,
It is particularly desirable to use hydrous silicic acid.

It is desirable that these synthetic amorphous silicas have a number average particle diameter of 2 to 13 μm. In the synthetic amorphous silica contained in the coating liquid, the larger the number average particle diameter, the wider the dot diameter from the viewpoint of the print density, which is preferable. However, when the number average particle diameter of the synthetic amorphous silica contained in the coating liquid exceeds 13 μm, the smoothness of the surface of the inkjet recording paper is deteriorated and so-called roughness is generated, which is not preferable. Further, if the number average particle diameter of the synthetic amorphous silica contained in the coating liquid is smaller than 2 μm, the printing density becomes low, which is not preferable.

Further, the synthetic amorphous silica has a specific surface area of 1
00 g / m ² or more is preferable, and 200 is more preferable.
It is g / m ² or more, and the pore volume is 0.5 ml / g or more, and more preferably 1.0 ml / g or more. If the specific surface area is smaller than 100 g / m ² and the pore volume is smaller than 0.5 ml / g, the absorption of ink droplets is insufficient, which is not preferable.

The coating liquid contains at least the above-mentioned synthetic amorphous silica and an aqueous binder. As the aqueous binder, polyvinyl alcohol and / or silanol-modified polyvinyl alcohol are required. Polyvinyl alcohol and / or silanol-modified polyvinyl alcohol is added in an amount of 20 parts by weight or more and less than 40 parts by weight with respect to 100 parts by weight of synthetic amorphous silica. If the amount of polyvinyl alcohol and / or silanol-modified polyvinyl alcohol added is less than 20% by weight, the color density tends to decrease due to insufficient spread of the ink dot diameter, and the binder effect decreases, resulting in powder falling. On the other hand, when the amount is 40 parts by weight or more, character bleeding is likely to occur.

In the present invention, the coating liquid may contain an appropriate amount of other binder within a range that does not impair the effect of the coating layer. Examples of such a binder include water-soluble polymers such as starch, cationized tempun, casein, gelatin, carboxymethyl cellulose, hydroxyethyl cellulose and polyvinylpyrrolidone, and water-dispersible polymers such as styrene butadiene latex and acrylic emulsion. Etc.

Further, in the present invention, polyamine polyamide epichlorohydrin is contained as a waterproofing agent. The polyamine polyamide epichlorohydrin is contained in the coating liquid in an amount of 40 to 9 per 100 parts by weight of the synthetic amorphous silica.
0 parts by weight are added. If the amount of polyamine polyamide epichlorohydrin added is less than 40 parts by weight, fixing of the dye in the ink at the upper part of the coating layer is insufficient, so that the color density tends to decrease, and the printed recording paper absorbs water during storage. As a result of squeezing and the dye in the ink liquid being eluted, the quality of the printed image tends to be unclear. Further, when the amount of polyamine polyamide epichlorohydrin added is more than 90 parts by weight, character bleeding is likely to occur.

Other than the polyamine polyamide epichlorohydrin, it is also possible to use other cation resins as the water-proofing agent, as long as the effects of the present invention are not impaired. Examples of such cationic resin include polyethyleneimine, polyamine sulfone, dimethyldiallylammonium chloride polymer, cationic polyacrylamide, and colloidal silica.

In addition to the above-mentioned components, the coating liquid may contain a white pigment other than synthetic amorphous silica, a light resistance improver, a surfactant, and other additives, if necessary. As white pigments other than synthetic amorphous silica, calcium carbonate, kaolin, talc, clay, diatomaceous earth, magnesium silicate, calcium silicate, alumina, zeolite,
Examples thereof include barium sulfate, urea resin, melamine resin and the like. In the present invention, as the white pigment, the above-mentioned synthetic amorphous silica may be used alone, or another white pigment may be used in an appropriate amount in combination with the synthetic amorphous silica.

Examples of the light resistance improver include zinc sulfate, zinc oxide, hindered amine antioxidants, and benzotriazole ultraviolet absorbers such as benzophenone.
Of these, zinc sulfate is particularly preferable. Further, as the surfactant, an anionic surfactant such as carboxylate, sulfonate, sulfate ester salt, and phosphate ester salt,
Examples thereof include ether type and ether ester type nonionic surfactants, amphoteric surfactants such as betaine, aminocarboxylic acid salts and imidazoline derivatives. Among these surfactants, a sulfonate is particularly preferable, and a dialkylsulfosuccinic acid ester salt is more preferable. The amount of the dialkyl sulfosuccinate ester salt is 5 parts by weight or more, preferably 5 parts by weight to 10 parts by weight, based on 100 parts by weight of the synthetic amorphous silica in the coating liquid. If the amount of the dialkyl sulfosuccinate ester salt added is less than 5 parts by weight with respect to 100 parts by weight of the synthetic amorphous silica, bleeding of letters is likely to occur, while if it is more than 10 parts by weight, the color density decreases. Is likely to occur.

Examples of other additives to be added to the ink receiving layer include pigment dispersants, thickeners, defoamers, dyes, optical brighteners, preservatives and pH adjusters.

As means for applying the coating liquid for forming the ink receiving layer as described above onto the support, a curtain coater, a roll coater, a reverse roll coater,
An air knife coater, a blade coater, a spray coater and the like can be mentioned, but a curtain coater is particularly preferable in the present invention. The curtain coater has an advantage that the surface of the ink receiving layer is excellent in smoothness.

In the present invention, the coating liquid is coated on the base paper in a solid content of 6 to 10 g / m ² to form an ink receiving layer. When the coating amount of the coating liquid is less than 6 g / m ² in terms of solid content, ink flow is likely to occur, while when it is more than 10 g / m ² , the density tends to decrease due to white spots.

In the present invention, the ink receiving layer is formed by applying the above-mentioned coating liquid on the base paper, but the ink receiving layer is not limited to one layer, and may be two layers. In the present invention, after the above-mentioned ink receiving layer is provided, an anionic surfactant is contained on the side opposite to the ink receiving layer and the surface tension is 4 or less.
It is desirable to apply an aqueous solution of 0 to 25 dyn / cm. By applying such an aqueous solution, it is possible to prevent the occurrence of curling and shrinking wrinkles of the inkjet recording paper,
In addition, the adhesion between the ink receiving layer and the back coat layer can be improved.

As the anionic surfactant in the above-mentioned aqueous liquid, (A) carboxylic acid type, (B) sulfate tester type,
Any of (C) sulfonic acid type and (D) other hydrophilic groups can be used. Examples of the (A) carboxylic acid type include fatty acid, rosin acid soap, and ether acid salt,
Examples of the (B) sulfate ester type include alkyl sulfate ester salts, sulfated oil and sulfate ester salts of fatty acid esters, fatty acid amide sulfate ester salts, and glycol ether sulfate ester salts, and as the (C) sulfonic acid type salts, Examples thereof include alkyl sulfonates, sulfosuccinic acid dialkyl ester salts, alkyl allyl sulfonic acids, alkyl naphthalene sulfonates, alkyl amide sulfonates, alkyl ester sulfonates, and (D) other hydrophilic groups include phosphorus. An acid ester is mentioned. Among these anionic surfactants, a sulfosuccinic acid dialkyl ester salt is preferable, and a sulfosuccinic acid diethylhexyl ester salt is more preferable. As the sulfosuccinic acid diethylhexyl ester salt, sulfosuccinic acid di-2-ethylhexyl ester is particularly preferable,
It is preferable that the content is 01 to 0.03% by weight.

In order to prevent curling and shrinking wrinkles of the ink jet recording paper, these anionic surfactants are contained and the surface tension of the aqueous solution thereof is 25 to 40 dyn /.
It is desirable to apply a 5 cm / cm ² or more aqueous liquid to the surface opposite to the ink receiving layer. To prevent the occurrence of curling and shrinking wrinkles, it is necessary to apply water of 5 cc / m ² or more, but if water is simply applied, shrinkage wrinkles are generated on the inkjet recording paper during drying. In this case, when an aqueous solution containing an anionic surfactant and having a surface tension of 25 to 40 dyn / cm is applied, shrinkage and wrinkles can be prevented and curling can be prevented.

In addition to the anionic surfactant, the aqueous liquid applied to the side opposite to the ink receiving layer contains an antifoaming agent, a defoaming agent,
Dyes, optical brighteners, preservatives and the like can be added as necessary. The means for applying the aqueous liquid may be a curtain coater, a bar coater, a gravure coater, a roll coater, a reverse roll coater, an air knife coater, a blade coater, a spray coater, or the like.

The drying temperature is preferably 80 ° C. or higher, more preferably 100 ° C. or higher, in order to make curl adjustment efficient. Further, it is desirable to dry the coated surface of the aqueous liquid such that the coated surface is in contact with the drum dryer. When the ink receiving layer has two or more layers, it is desirable to apply the above-mentioned aqueous liquid to the opposite surface every time the ink receiving layer is applied.

The components of the base paper and the ink receiving layer are not limited to those described above in terms of preventing only curling and shrinking wrinkles of the ink jet recording paper. That is, the base paper may be one in which a part of wood pulp is replaced with straw, non-wood pulp such as esparto and kenaf, or synthetic pulp or synthetic fiber such as polyethylene and polypropylene, and the ink receiving layer is usually known. It may be one.

The ink jet recording method of the present invention uses the above ink jet recording paper and has a resolution of 180-180.
A recorded image is formed by a 720 DPI inkjet printer. The inkjet recording paper of the present invention is
Even in the case of recording an image with such a high-resolution inkjet printer, the color density is high, images such as characters are not bleed, the water resistance is good, and the powder drop is extremely small. However, in the case of an inkjet printer having a DPI of 100 DPI or less, the spread of the ink is insufficient, resulting in a "blank" defect, while in the case of an inkjet printer having a DPI of 1000 DPI or more, the ink overlaps and a "blurring" defect occurs.

As the recording liquid applied to the ink jet recording method of the present invention, both a dye type recording liquid and a pigment type recording liquid can be used. Dye type recording liquids include recording liquids containing water-soluble dyes such as direct dyes, acid dyes, reactive dyes and basic dyes.

As the dye type recording liquid, the following four color recording liquids are usually used. For the preparation of yellow, magenta, cyan and black recording liquids, one or two or more water-soluble dyes are added in an amount of 0.2 to 15 parts by weight based on the total weight of the ink composition in the recording liquid of each color. Is preferably added in an amount of 0.5 to 10 parts by weight, and most preferably 2 to 9 parts by weight.

The recording liquid can be used by mixing with the following solvents in addition to water. For example, methyl alcohol, ethyl alcohol, n-propyl alcohol, isopropyl alcohol, n-butyl alcohol, sec
-Butyl alcohol, tert-butyl alcohol, isobutyl alcohol, pentyl alcohol, hexyl alcohol, heptyl alcohol, octyl alcohol,
Nonyl alcohol, decyl alcohol, etc. having 1 to 1 carbon atoms
10 alkyl alcohols;

For example, an aliphatic or aromatic hydrocarbon solvent represented by cyclopentane, hexane, cyclohexane, heptane, octane, nonane, decane, undecane, dodecane, tridecanone, tetralin, decalin, benzene, toluene, xylene, etc., A halogenated hydrocarbon solvent such as carbon tetrachloride, trichloroethylene, tetrachloroethylene, dichlorobenzene, etc .; an ether solvent such as ethyl ether, butyl ether, ethylene glycol diethyl ether, ethylene glycol monoethyl ether; ,acetone,
Ketone-based solvents such as methyl ethyl ketone, methyl propyl ketone, methyl amyl ketone, and cyclohexanone;
For example, ester solvents such as ethyl formate, methyl acetate, ethyl acetate, propyl acetate, butyl acetate, phenyl acetate, ethylene glycol monoethyl ether acetate, ethyl lactate, etc .;

For example, polyhydric alcohols such as ethylene glycol, diethylene glycol, propylene glycol and glycerin; other amines, amides, N-methyl-2-pyrrolidone, 1,3-dimethyl-2-imidazolidinone, etc. Intramolecular ester solvents of oxycarboxylic acids such as nitrogen-containing heterocyclic system, valerolactone, caprolactone, dimethyl sulfone, diethyl sulfone, bis (2-
Chloroethyl) sulfone, aliphatic sulfone compound-based solvent such as methylsulfonylacetonitrile, alicyclic sulfone compound-based solvent such as sulfolane and sulforene, various solvents of sulfoxide compound-based solvent such as tetramethylene sulfoxide and 3-methyltetramethylene sulfoxide Can be mentioned.

The pigment-type recording liquid is preferably a recording liquid in which fine pigment particles are dispersed in an aqueous dispersion medium containing a polymer having a hydrophilic constituent portion and a hydrophobic constituent portion and a water-soluble organic solvent. These polymers have a molecular weight of 1000 to 10
Approximately 10,000 polyacrylic acid, polymethacrylic acid, condensed naphthalene sulfonic acid, styrene-maleic acid and the like can be mentioned, and salts of these polymers can be formed and solubilized or dispersed in an aqueous liquid. Examples of the component that forms the above-mentioned polymer salt include alkali metals, aliphatic amines, alcohol amines, morpholine, and N-morpholine.

The water-soluble organic solvent is preferably alcohols, especially polyhydric alcohols. And with the above polymer,
Fine pigment particles are mixed and dispersed with an aqueous organic solvent and water to obtain a recording liquid having a predetermined viscosity range. As the pigment fine particles used in this recording liquid, various known organic pigments such as azo type, phthalocyanine type, quinacridone type, anthraquinone type, dioxazine type, indigo type and perinone type can be used.

[0037]

The present invention will be described below with reference to examples, but the present invention is not limited thereto.

Example 1 <Preparation of base paper> Wood pulp consisting of 80 parts by weight of LBKP and 20 parts by weight of NBKP was beaten using a disc finaly to obtain a pulp slurry having a Canadian freeness of 400 ml. While stirring the obtained pulp slurry, 5 parts by weight of talc, 1.2 parts by weight of rosin, 1.5 parts by weight of starch, and 1.5 parts by weight of aluminum sulfate were added to 100 parts by weight of the pulp. Base paper having a basis weight of 80 g / m ^{2 was made} by a paper machine. Oxidized starch was converted to a solid content of 1.0 g /
m ^{2 was} adhered and used as a base paper for coating. Base paper thickness is 95μ
m, Cobb water absorption was 21.0 g / m ² .

<Preparation of Coating Liquid and Coating of Coating Layer> 100 parts by weight of synthetic amorphous silica (oil absorption 230 ml / 100 g, number average particle diameter 5.5 μm) Polymerization degree 1700 silanol-modified PVA 26 Parts by weight Polyamide polyamine epichlorohydrin 65 parts by weight Zinc sulfate 10 parts by weight Sodium di4 methylpentylsulfosuccinate 7 parts by weight Water was added to the above composition to prepare a coating solution having a solid content of 20% by weight. This coating solution was applied to a base paper as a solid content by 10 g / m ² with a curtain coater and subjected to on-machine gloss calendering to obtain an inkjet recording paper of Example 1.

Examples 2 to 7 Example 1 was repeated except that the coating liquids had the compositions shown in Table 1, respectively.
Inkjet recording sheets of Examples 2 to 7 were obtained in the same manner as in. In addition, the numerical value in the composition in Table 1 shows a weight part.

Comparative Example 1 to Comparative Example 5 Example 1 was repeated except that the coating solutions had the compositions shown in Table 2.
Inkjet recording papers of Comparative Examples 1 to 5 were obtained in the same manner as in. In addition, the numerical value in the composition in Table 2 shows a weight part.

Next, the image density, character bleeding, water resistance, and powder drop of the obtained ink jet recording paper were evaluated, and the results are shown in Table 1 and Table 2, respectively. <Evaluation method> (1) Image density HP inkjet printer DW660C (300D
PI) (manufactured by Nihon Fute Packard Co., Ltd.) was used for solid printing with black ink, and the image density was measured with a Macbeth densitometer. (2) Character blurring HP inkjet printer DW66C (300DP
I) The font name Dom Casual (10 points) was printed with black ink using [manufactured by Nippon Fute Packard Co., Ltd.], and the degree of bleeding was visually evaluated. ○ ・ ・ ・ ・ Good with almost no bleeding △ ・ ・ ・ ・ There is bleeding but within the practical upper limit. × ... ・ There are many bleeds and outside the practical upper limit. (3) Water resistance 5 After immersion for a minute, water resistance was evaluated by the presence or absence of ink elution. O indicates that the ink was eluted, and X indicates that the ink was not eluted. (4) Powder falling friction tester [HEIDON-18: manufactured by Shinto Scientific Co., Ltd.]
Using, a 900 g weight was rotated on the sample, and the degree of powder falling on the sample surface was evaluated. ○ ・ ・ ・ ・ There is almost no powder drop × ・ ・ ・

[0043]

[Table 1]

From Table 1, the ink jet recording sheets of the present invention shown in Examples 1 to 7 have high image densities of 1,41 or more even when a recorded image is formed by an ink jet printer having a high resolution of 300 DPI. It can be seen that there is almost no character bleeding, the water resistance is high, the ink is not eluted, and the powder is hardly removed by friction on the surface.

[0045]

[Table 2]

The following can be seen from Table 2. Comparative Example 1 in which silanol-modified polyvinyl alcohol was as small as 17 parts by weight
Has a low image density and a large amount of powder is removed. In Comparative Example 2 in which the silanol-modified polyvinyl alcohol is as large as 45 parts by weight, the image density is high, but the characters are often blurred. In Comparative Example 3 and Comparative Example 4 in which the amount of polyamide polyamine epichlorohydrin was as small as 30 parts by weight, the image density was low, the water resistance was low, and ink was eluted. Further, in Comparative Example 5 in which the amount of polyamidepolyamine epichlorohydrin is as large as 110 parts by weight, the image density is high, but the characters are often blurred.

[0047]

As described above, according to the present invention,
Even when forming a recorded image with a high-resolution 720DPI inkjet printer, the image density is high, there is almost no character bleeding, the water resistance is high, ink does not elute, and most of the powder is removed by friction on the surface. Absent.

Claims (4)

[Claims] 1. An inkjet recording paper comprising a base paper mainly composed of wood pulp and a coating layer containing a pigment provided on the base paper.
The coating layer contains polyvinyl alcohol and / or silanol-modified polyvinyl alcohol in an amount of 20 parts by weight or more and less than 40 parts by weight and polyamide polyamine epichlorohydrin in an amount of 40 to 90 parts by weight based on 100 parts by weight of the synthetic amorphous silica.
An ink jet recording paper, characterized in that it is formed by coating a coating liquid containing a part by weight. 2. The ink jet recording paper according to claim 1, wherein the coating liquid further contains 5 parts by weight or more of dialkylsulfosuccinic acid with respect to 100 parts by weight of synthetic amorphous silica. 3. A recording method using the inkjet recording paper according to claim 1 to perform a recorded image with an inkjet printer having a resolution of 180 to 720 DPI. 4. A recording method using the inkjet recording paper according to claim 2 to perform a recording image with an inkjet printer having a resolution of 180 to 720 DPI.