JP2002274022A - Ink jet recording medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ink jet recording medium excellent in color developing properties and ink absorbency even when printing is executed by any ink jet printer not only with a dye ink but also with an ink mainly made of a pigment ink. SOLUTION: In the ink jet recording medium, in which an ink receiving layer is provided on a support, the ink receiving layer is provided by coating and drying a coating liquid for the ink receiving layer including a vapor phase silica dispersant compounded with the hydroxide of alkali metal, a colloidal silica and a resin onto the support.

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 suitable for recording using a pigment ink, and more particularly to an ink jet recording medium having improved ink coloring.

[0002]

2. Description of the Related Art Ink jet recording systems have been rapidly spread in recent years due to the fact that full color printing is easy and printing noise is small. In this method, ink droplets are ejected from a nozzle toward a recording medium at a high speed, and a large amount of solvent is contained in the ink. Therefore, it is necessary for the recording medium to quickly absorb the ink. Further, with the recent spread of computers and digital cameras, images close to silver halide photographs have been demanded. Therefore, high color developability, resolution and color reproducibility are required for inkjet recording paper.

Particularly in the field of full-color recording, printers using a so-called dye ink in which a dye excellent in color developing property is dissolved in a solvent, are mainly used. On the other hand, a printer using a so-called pigment ink in which a pigment is dispersed is excellent in light resistance and water resistance, but is inferior in color reproducibility of an image, and therefore outputs a coarse image on a large-sized recording medium such as a poster. It is mainly used for such specific uses.

On the other hand, the use of fumed silica as a pigment for the ink receiving layer is disclosed in Japanese Patent Publication No. 3-56552, Japanese Patent Application Laid-Open No. H10-81064, and Japanese Patent Application Laid-Open No. H11-48602.
And Japanese Patent Application Laid-Open No. 11-58938. However, the above-mentioned conventional recording sheet does not sufficiently satisfy the color developability when inkjet recording is performed using a pigment ink.

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to provide an ink jet recording medium for pigment ink which has particularly good coloring properties when printed by an ink jet printer using not only dye ink but also pigment ink. .

[0006]

Means for Solving the Problems The inventors of the present invention have found that when the ink-receiving layer contains fumed silica and colloidal silica, the balance between the strength of the ink-receiving layer and the ink absorptivity is improved. The inventors have found that the use of an alkali metal hydroxide as a dispersing aid when dispersing silica by a method improves the color developability of an ink jet recording medium, and has reached the present invention.

Accordingly, an object of the present invention is to provide (1) a pigment ink jet recording medium having an ink receiving layer provided on a support, wherein a fumed silica dispersion containing an alkali metal, colloidal silica, An ink-jet recording medium provided with an ink-receiving layer by applying and drying a coating liquid for an ink-receiving layer containing a resin, and (2) an alkali metal in a gas-phase method silica dispersion in a vapor phase. This is achieved by the ink jet recording medium described in (1), wherein 0.1 to 0.5 part by weight is added to 100 parts by weight of the process silica.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail.
The support used in the present invention is not particularly limited,
It may be transparent or opaque. For example, cellophane, polyethylene, polypropylene, soft polyvinyl chloride, hard polyvinyl chloride, plastic films such as polyester, high quality paper, photographic paper base paper, drawing paper, drawing paper,
Art paper, coated paper, cast coated paper, kraft paper,
Examples include impregnated paper and synthetic paper, which can be used as appropriate according to the intended use. In particular, it is preferable to use a support having ink absorbency.

The average particle size of the pigment contained in the ink receiving layer is preferably from 20 to 500 nm, and particularly preferably from 10 to 500 nm.
It is preferably from 0 to 400 nm. Average particle size is 2
When the thickness is smaller than 0 nm, the transparency of the coating film itself is improved, but the number of voids is reduced, so that the ink absorbency becomes insufficient. Furthermore, if the average particle diameter is too small, the film formability of the coating film is poor and the surface becomes cracked when the coating film is thickened,
In addition, since there are few voids on the surface, ink absorbency is poor. If the average particle size is larger than 500 nm, the glossiness of the white paper is reduced, so that the feeling of plain paper becomes stronger and the image becomes cheaper.
It is not preferable because the ink easily penetrates deeply and the color developability becomes insufficient particularly in a printing portion where the ink is hardly applied. In particular, if the average particle diameter is too large, the fluidity as a colloidal liquid is significantly reduced, and thus the workability and productivity are also deteriorated.

The pigment in the ink receiving layer may be a pigment composed of secondary particles composed of fine primary particles. Particularly, the fine primary particles may be in the form of a chain, a network, a ring or a partial ring. It is preferable that the pigment has a continuous shape. Average primary particle diameter of fine particles is 5 to 60 nm
Is fine. If the average primary particle size is less than 5 nm, the ink absorbency is poor. If the average primary particle size is more than 60 nm, the transparency of the recording layer is reduced, and it is difficult to obtain high color development. Particularly preferred average primary particle diameter is 10 to 50 nm. Pigments satisfying such requirements include fumed silica and colloidal silica. Next, the fumed silica and the colloidal silica used in the present invention will be described.

The fumed silica used in the present invention is also called a dry method with respect to a wet method, and is generally produced by a flame hydrolysis method. Specifically, a method of burning silicon tetrachloride together with hydrogen and oxygen is generally known, but instead of silicon tetrachloride, silanes such as methyltrichlorosilane and trichlorosilane may be used alone or silicon tetrachloride. Can be used in a mixed state. The fumed silica is commercially available from Nippon Aerosil Co., Ltd. as Aerosil and can be easily obtained.

The average particle diameter of the primary particles of the fumed silica used in the present invention is preferably 50 nm or less, and more preferably 5 to 30 nm. The feature of the fumed silica is that the primary particles are connected in a network structure or a chain form in the ink receiving layer and are present in a secondary agglomerated state. The absorption capacity is improved.

An aqueous dispersion of fumed silica can be obtained relatively easily by simply mixing and stirring with water, and the viscosity of an aqueous dispersion of fumed silica depends on pH. It is known that the viscosity becomes highest when the pH of the aqueous dispersion is around neutral, and the viscosity becomes lower as the pH becomes acidic or alkaline. When the viscosity of the dispersion is low, the coatability of the coating liquid for the ink receiving layer is improved, which is preferable.

The colloidal silica of the present invention is a synthetic silica having a primary particle diameter of about several nm to 100 nm synthesized by a wet method. Colloidal silica has many hydroxyl groups on the surface and the inside is thought to form a siloxane bond,
It has features such as binding and film forming properties. The ink fixing efficiency, which affects the ink fixing property and the color developing property, is good, and the abrasion resistance is good due to dense clogging. However, if the pigment of the ink receiving layer is only colloidal silica, it is difficult to obtain a sufficient coating amount, and as a result, it is difficult to obtain a sufficient ink absorption capacity.

In the present invention, hydroxides of alkali metals such as sodium, potassium and lithium are used as a dispersing aid for the fumed silica dispersion, and sodium hydroxide and potassium hydroxide are particularly preferred. The added amount of the alkali metal hydroxide is preferably 0.1 to 0.5 part by weight, and more preferably 0.3 to 0.5 part by weight based on 100 parts by weight of the fumed silica.
0.4 parts by weight is more preferred. When the addition amount is less than 0.1 part by weight, the effect of addition is not exhibited, and when it is more than 0.5 part by weight, fumed silica may be dissolved at the time of dispersion.

Although the reason for the effect of the alkali metal hydroxide as the dispersing aid in the present invention is not clear, colloidal silica is a siloxane bond formed by hydroxide ions as a catalyst in an alkali dispersion medium or a dispersion solution. It is known to produce and gel. Therefore, the inkjet recording medium of the present invention can be formed into a dense and hard ink-receiving layer by hydroxide ions of hydroxides of alkali metals such as sodium, potassium, and lithium added in the dispersion solution. It is considered that high color developability is obtained because a large amount of pigment ink remains on the surface of the recording medium.

The ink receiving layer containing fumed silica and colloidal silica preferably has a binder in order to maintain the properties as a coating film. Examples of the binder include polyvinyl alcohol and modified products thereof, vinyl acetate, oxidized starch, etherified starch, casein, gelatin, soy protein, carboxymethyl cellulose, SB latex, NB latex, acrylic latex, ethylene vinyl acetate latex, and polyurethane. And unsaturated polyester resins. In the present invention, at least one of these binders can be used.
The amount is preferably 3 to 60 parts with respect to 100 parts by weight. If the amount of the binder is small, the surface strength becomes insufficient, while if it is too large, the ink absorbency becomes insufficient.

In the ink jet recording medium of the present invention, two or more ink receiving layers may be provided. It is preferable to provide two or more ink receiving layers because the glossiness can be easily adjusted. If the coating amount of the ink receiving layer is too small, the absorption of the ink solvent becomes insufficient, so that bleeding is remarkably observed particularly in an image of a mixed color system. In addition, if the coating amount of the ink receiving layer is too large, the wound layer may be used as a lithographic plate, or when making a small judgment, the coated layer may fall into a powder form from the support, or the printed portion may be rubbed. It is not preferable because the surface strength becomes insufficient such that the coating layer falls off. The coating amount of the ink receiving layer can be appropriately determined according to the purpose, but the preferable coating amount of one ink receiving layer is 3 to 15 g / m ² , and the particularly preferable coating amount is 5 to 10 g / m ² . is there.

In the present invention, an under layer mainly for absorbing an ink solvent can be provided between the ink receiving layer and the support. Generally, the higher the resolution of an ink jet printer, the greater the amount of ink applied per unit area. Therefore, it is preferable to provide an under layer on the recording medium to increase the ink absorption capacity.

Examples of pigments for the under layer include synthetic silica, alumina and alumina hydrate (alumina sol, colloidal alumina, pseudoboehmite, etc.), aluminum silicate, magnesium silicate, magnesium carbonate, light calcium carbonate,
Inorganic pigments such as heavy calcium carbonate, kaolin, talc, calcium sulfate, titanium dioxide, zinc oxide, zinc carbonate, calcium silicate, aluminum hydroxide, etc., as well as organic pigments such as plastic pigments and urea resins can be used. . Also, as a binder for the under layer,
The same thing as the case of the above-mentioned ink receiving layer is preferably used.

Further, in the ink jet recording medium of the present invention, a pigment dispersant,
Thickener, defoamer, defoamer, release agent, foaming agent, coloring dye,
A coloring pigment, a fluorescent dye, an ultraviolet absorber, an antioxidant, an antiseptic, a water-proofing agent, a surfactant, a wet paper strength enhancer, and the like can be appropriately added as long as the effects of the invention are not impaired.

In order to provide the ink receiving layer on the surface of the support, various coating devices such as a blade coater, a roll coater, an air knife coater, a bar coater, etc.
Various devices such as a gate roll coater, a curtain coater, a short dwell coater, a gravure coater, a flexographic gravure coater, and a size press can be used on-machine or off-machine.

In the present invention, the surface of the support, the underlayer, and the surface of the ink-receiving layer may be subjected to a surface treatment using a calender such as a machine calender, a super calender, or a soft calender, as long as the effects of the present invention are not impaired. It is possible.

[0024]

EXAMPLES The present invention will be described in more detail with reference to the following Examples, but it should not be construed that the invention is limited thereto. Also, “parts” and “%” shown in the examples
Indicates parts by weight and% by weight unless otherwise specified, and the number of parts indicates solids. <Example 1> Base paper) 90% of hardwood bleached kraft pulp and 10% of softwood bleached kraft pulp were mixed and beaten to obtain a freeness of 350 ml.
100 parts of the pulp adjusted to cationized starch 4
Parts, anionized polyacrylamide 0.3 part, and alkyl ketene dimer emulsion 0.5 part were added to form a web with a Fourdrinier paper machine. After performing three-stage wet press, and then performing two-stage tension press in the drying part and drying,
A solution containing 5% of phosphorylated esterified starch and 0.5% of polyvinyl alcohol is applied using a size press so that the dry weight becomes 3.6 g / m ^2, and after drying, machine calendering is performed to obtain a basis weight of 175 g. / M ² was produced.

Ink receiving layer: under layer) Synthetic amorphous silica (Fine Seal X-37B manufactured by Tokuyama Corporation)
60 parts, synthetic amorphous silica (Fine Seal X-12)
Tokuyama Corporation) 40 parts, polyvinyl alcohol (P
VA-117, manufactured by Kuraray Co., Ltd.) 25 parts, ethylene vinyl acetate emulsion (Sumika Flex 401, manufactured by Sumitomo Chemical)
4 parts, styrene butadiene latex (LX438C
4 parts of Nippon Zeon), 2 parts of styrene acrylic resin (Polymalon 360), 4 parts of polydiallyldimethylammonium chloride (PAS-H-10L manufactured by Nitto Boseki), 0.5 parts of defoamer (SN Deformer 480, manufactured by San Nopco)
Parts, a bluing agent of 0.012 parts, a fluorescent dye of 0.7 parts and a dilution water, etc. were appropriately added. A color having a solid content of 22% was dried using a bar blade coater at a dry coating amount of 16 g.
/ M ² .

Gas phase silica dispersion) 64.9 parts of water, 0.1 part of sodium hydroxide, and 35 parts of Aerosil 50 (manufactured by Nippon Aerosil Co., Ltd.) are mixed and stirred for 30 minutes by a Serie mixer, and the silica of the gas phase silica is mixed. A dispersion was obtained. Ink receiving layer: lower layer) 30 parts of the above-mentioned fumed silica dispersion in solid content, colloidal silica (Snowtex PS-
M, manufactured by Nissan Chemical Industries, Ltd.) in a solid content of 70 parts, polyvinyl alcohol (PVA-117, manufactured by Kuraray) 8 parts, an antifoaming agent (SN)
A color having a solid content of 22% was prepared by mixing 0.5 parts of Deformer 480 (manufactured by San Nopco) and diluting water, and dried with a bar blade coater to a dry coating amount of 7 g / m.
² was applied. Ink receiving layer: upper layer) 75 parts of the above-mentioned fumed silica dispersion in solid content, colloidal silica (Snowtex PS-
M, manufactured by Nissan Chemical Co., Ltd.) in a solid content of 25 parts, polyvinyl alcohol (PVA-117, manufactured by Kuraray) 8 parts, an antifoaming agent (SN)
Deformer 480) 0.5 part and dilution water were mixed,
A color having a solid content of 26% was prepared, and this was coated using a bar blade coater so that the dry coating amount was 7 g / m ² to obtain an ink jet recording medium.

Comparative Example 1 An ink jet recording medium was prepared in exactly the same manner as in Example 1 except that sodium hydroxide was not added in the dispersion of fumed silica. <Comparative Example 2> An ink jet recording medium was used in the same manner as in Example 1 except that 0.1 part of sodium hydroxide was used instead of 0.1 part of sodium hydroxide in dispersion of fumed silica. Was prepared.

Comparative Example 3 The upper layer was dispersed except that 0.2 parts of aqueous ammonia (by weight of NH ₃ ) was used instead of 0.1 parts of sodium hydroxide in the dispersion of fumed silica.
An ink jet recording medium was produced for the lower layer in exactly the same manner as in Example 1. <Comparative Example 4> Except that 0.1 part of sodium hydroxide was used in place of 0.1 part of sodium hydroxide in dispersing fumed silica, 1 part of aqueous ammonia (by weight of NH ₃ ) was used in both the upper layer and the lower layer. To produce an ink jet recording medium.

Evaluation method) Each of the recording media of Examples and Comparative Examples was evaluated by the following methods. For each item, a rating of △ or more is practical.
In addition, regarding the inkjet recording evaluation, a commercially available pigment ink type inkjet printer MC-200 was used.
0 (Seiko Epson: inkjet printer)
Was used.

[Evaluation Items] <Color Development> Each solid image was printed for black, cyan, magenta, and yellow, and after standing for one day, the print density of each image portion was measured using a reflection densitometer (MACHBETH RD91).
Measured in 4). The higher the density value of the total of four colors, the better the color developability. <Ink Absorption> Each solid image of red and green was printed next to each other, and the degree of bleeding at the boundary was evaluated. ：: The boundary is clear and no bleeding is observed. Δ: The boundary is slightly unclear but no bleeding is observed. X: The boundary is unclear and bleeding is observed. The results of the evaluation are as shown in Table 1.

[0031]

[Table 1]

As is evident from Table 1, the ink jet recording medium prepared in Example 1 has good color developability and ink absorbency, and particularly has high print densities of yellow and cyan. On the other hand, the coloring properties of the ink jet recording media produced in Comparative Examples 1 to 4 are inferior. In Comparative Examples 2 and 4, the ink absorbency was also poor.

According to the method of the present invention, it is possible to obtain an ink jet recording medium having excellent coloring properties when printed with a pigment ink.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Susumu Hagisawa 5-2-1-1, Oji, Kita-ku, Tokyo Nippon Paper Industries Co., Ltd. (72) Inventor Atsushi Atsushi 5-2-1, Oji, Kita-ku, Tokyo No. Nippon Paper Industries Co., Ltd. F-term (reference) 2C056 EA05 FC06 2H086 BA15 BA31 BA33 BA34 BA55

Claims (2)

[Claims] An ink jet recording medium for a pigment ink having an ink receiving layer on a support, wherein the ink comprises a fumed silica dispersion containing an alkali metal hydroxide, colloidal silica, and a resin. An ink jet recording medium provided with an ink receiving layer by applying and drying a coating liquid for a receiving layer on a support. 2. An alkali metal hydroxide is added in an amount of 0.1 to 100 parts by weight of fumed silica in the fumed silica dispersion.
2. The ink jet recording medium according to claim 1, wherein 0.5 parts by weight are added.