JPS60232990A - Ink jet recording medium - Google Patents

Abstract

PURPOSE:To obtain a recording medium excellent in water resistance and light resistance of a water-soluble dye and having capability suitable for forming multicolor images with high density and high precision, by incorporating a porous cationic hydrated aluminum oxide into at least one ink-receiving layer. CONSTITUTION:The porous cationic hydrated aluminum oxide used here can be obtained by a method wherein an aqueous solution of an aluminum salt such as aluminum sulfate, aluminum nitrate, aluminum chloride and other similar substances, an alkali metal aluminate such as sodium aluminate and potassium aluminate, or both of the water-soluble aluminum compounds is subjected to neutralization or ion exchange using an ion-exchange resin to obtain a gel, which is ordinarily washed to remove salts, followed by drying to obtain a xero gel. When drying is conducted by spray drying or the like, the hydrated oxide can be obtained in a particulate form suitable for mixing in a coating liquid. The hydrated oxide obtained after drying is devoid of most of free water, is ordinarily devoid of some of bound water, and is in the form of a porous solid, with a major part of the structure thereof being irreversibly set.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a recording medium on which ink is recorded, and in particular, the images and characters recorded on the medium have high density, clear color tone, and excellent ink absorption ability. The present invention relates to an inkjet recording medium particularly suitable for multicolor recording.

The inkjet recording method uses a single operating principle to fly minute droplets of ink and attach them to a recording medium such as - to record images, characters, etc.; It is easy to print, has great flexibility in recording patterns, and does not require development or fixing, so it has rapidly become popular in a variety of applications as a recording device for various shapes and color images, including kanji. There is. Furthermore, images formed using the multicolor inkjet method can produce records that are comparable to multicolor printing using the plate making method or printing using the color photographic method, making it suitable for applications that require fewer copies to be produced. Since it is cheaper than photographic technology, it is being widely applied to the field of full-color image recording.

Efforts have been made in terms of equipment and ink composition to use high-quality paper or coated paper, which are used for ordinary printing and writing, as the recording medium used in this inkjet recording method. However, as the performance of inkjet recording apparatuses improves, such as higher speed ratios, higher definition, or full color inkjet recording apparatuses, and their applications expand, more advanced characteristics are now required of recording media. In other words, the recording medium must have high ink dot density, bright and colorful tones, fast ink absorption and no ink bleeding or bleeding even when ink dots overlap, and ink dots with high density and bright colors. The lateral diffusion of the material should not be unnecessarily large, and the surrounding area should be smooth and not blurry. Furthermore, it is required that the resistance of the dye when the recorded image is exposed to ultraviolet rays, oxygen in the air, or water be not reduced, but preferably increased.

- Several proposals have been made in the past to solve all of these problems. For example, Japanese Patent Application Laid-Open No. 52-53012 discloses an inkjet recording paper made by moistening a low-size base paper with a surface treatment charge.
No. 9113 discloses an inkjet recording paper in which a sheet containing urea-formalin resin powder is impregnated with a water-soluble polymer. These patterned paper-type inkjet recording papers absorb ink quickly, but
There are a hundred disadvantages that the periphery of the dot tends to be blurred and the dot density is low.

Further, JP-A No. 55-5830 discloses an inkjet recording paper in which an ink-absorbing coating layer is provided on the surface of the support, and JP-A No. 55-51583 discloses a non-glue pigment as a pigment in the coating layer. An example using silica powder is disclosed, and furthermore, JP-A-55-11829 discloses an example of smear paper using a two-layer structure with different ink absorption speeds. These coated paper-type inkjet recording papers are improved over general paper-type inkjet papers in terms of dot diameter, dot shape, dot density, and color tone reproducibility, but there are Many inks are water-based inks that use water-bathable dyes, and when an image formed on a recording medium is exposed to water, the dye dissolves again and oozes out, significantly reducing the value of the recorded material. There is a point.

Therefore, in order to completely improve this drawback, for example, Japanese Patent Laid-Open No. 1i8
No. 55-53591 describes an example in which a metal water-bathable salt is applied to the recording surface, and JP-A No. 56-84992 describes an example of a recording medium containing a polycationic polymer electrolyte on the entire surface. JP-A-55-150396 discloses a method of applying a water-resistant agent that forms a lake with the dye in the ink after inkjet recording, and JP-A-56-58869 also discloses a method of applying a waterproofing agent that forms a lake with the dye in the ink.
Each of these publications discloses a method of making a recording sheet coated with a water-soluble polymer waterproof by insolubilizing the water-bathable polymer after inkjet recording.

However, with these methods, the effect of water resistance is weak, or the water resistance agent causes some kind of reaction with the dye, reducing the shelf life of the dye, making it difficult to achieve both sufficient water resistance and light resistance. It was quite difficult.

The present inventor has conducted various studies in order to improve the water resistance and light resistance of aqueous ink images, and obtain the above-mentioned commercial success and high-definition inkjet images. We succeeded in slowing down the process and came up with the present invention.

That is, the present inventor has proposed an inkjet recording method in which a recorded image is obtained by jetting aqueous inkjet ink onto a recording medium, in which the recording medium has at least one ink receiving layer, and the ink receiver 3! By containing porous cationic water-injected aluminum oxide in the A layer, a record that has excellent water resistance and light resistance of water bath dyes and has the ability to form high-density, high-definition multicolor images. This is what I discovered that the medium can do.

It is not clear why the inkjet recording medium containing the cationic water-containing aluminum oxide according to the present invention can improve the water resistance of water bathing dyes and also improve the light resistance. However, water-based inks containing direct dyes or acid dyes that have an anionic dissociation fund are often used for inkjet inks, and the anionic dye in the ink and the cationic surface of the cationic aluminum oxide in the recording medium are often used. It is speculated that the ionic attraction between the two is involved.

The porous cationic water-containing aluminum oxides used in the present invention are aluminum salts such as aluminum sulfate, aluminum nitrate, aluminum chloride and the like, or alkali metal aluminates such as sodium or potassium aluminate salts. Alternatively, a gel obtained by neutralizing or ion-exchanging an aqueous solution of both water-bathable aluminum compounds using an ion-exchange resin, which is called a hydrogel, is washed to remove salts and then dried. It refers to the product obtained by making xeroge. If spray drying or the like is used for drying, it can be made into a powder suitable for blending into the Tokoyoshi coating solution. It is also possible to make a powder by drying it in block form and then crushing and classifying it. The hydrated oxide thus obtained after drying has most, if not all, of its free water removed, and usually some of its bound water as well, so that it has a thicker structure. is irreversibly set into a porous solid. The pore diameter of the porous solid thus obtained is usually 50 A0 to 5000 A', and the surface charge when the secondary particles are dispersed in water is a glass charge (cationic).

1. Is the content of the cationic aluminum oxide in the recording medium 1 t/rr? ~509/rr? , preferably from 3 t/d to 209 t/d, and if it is too small, the effect of making the water-soluble dye water resistant will be weak. There is no need to particularly limit the amount, but the above range is sufficient in terms of performance and θ cost.

The ink-receiving layer in the present invention refers to a layered layer having an ink-absorbing ability, which is formed from the cationic water-containing aluminum oxide and, if necessary, other pore-forming materials and an adhesive on a suitable support. .

Examples of pore forming materials include calcium carbonate, kaolin (white clay), talc, calcium sulfate, barium sulfate,
Titanium oxide, zinc oxide, zinc carbonate, aluminum silicate, aluminum hydroxide, aluminum oxide, calcium silicate, magnesium silicate, amorphous silica, and inorganic and organic pigments such as plastic pigments and urea resin pigments; It is also possible to use these together.

In order to form an ink-receiving layer by coating these pigments on a support, the above-mentioned colloidal silica and, if necessary, an adhesive for adhering the void forming material to the support are required. Examples of adhesives include oxidized starch, etherified starch, cellulose conductors such as carboxymethyl cellulose and hydroxyethyl cellulose, casein, gelatin, soybean protein, polyvinyl alcohol and its derivatives, maleic anhydride resin, and ordinary styrene. Conjugated diene polymer latex such as sorbadiene copolymer, methyl methacrylate-butadiene copolymer, acrylic polymer latex such as polymer or copolymer of acrylic acid, ester and methacrylic acid ester, ethylene vinyl acetate copolymer Vinyl polymer latex such as polymers, functional group-modified polymer latex with monomers containing functional groups such as carboxyl groups of these various polymers, water-based thermosetting synthetic resins such as melamine resin, urea resin, etc. Adhesives and synthetic resin adhesives such as polymethyl methacrylate, polyurethane resins, unsaturated polyester resins, vinyl chloride-vinyl acetate copolymers, polyvinyl butyral, and alkyd resins are used alone or in combination. These adhesives Fs,
The amount used is 2 parts to 100 parts, preferably 5 parts to 30 parts, per 100 parts of the pigment, but the ratio is not particularly limited as long as the amount is sufficient to bind the pigment. However, 10
If 0 parts or more of the adhesive is used, the adhesive will form a film, which will reduce the pore structure or make the pores extremely small, which is not preferable.

Pigment dispersants, thickeners, flow modifiers, antifoaming agents, foam inhibitors, mold release agents, foaming agents, penetrants, colored dyes, colored pigments, fluorescent whitening agents, and ultraviolet absorbers are required for refreshing. Agents, antioxidants, preservatives, anti-pepper agents, etc. can also be added as appropriate.

As the support, a sheet material such as paper or a thermoplastic resin film is used. In the case of paper, it may be paper without a sizing agent or with appropriate sizing, and may or may not include a loss charge.

In addition, in the case of thermoplastic films, polyester, polystyrene, polyvinyl chloride, polymethyl methacrylate,
A transparent film made of cellulose acetate, polyethylene, polycarbonate, etc., or a white opaque film filled with white pigment or made by fine foaming is used. Examples of white pigments to be filled include titanium oxide, calcium sulfate,
Calcium carbonate, silica, clay, talc, +1!2f
Many are used, such as zinc.

It is also possible to use so-called laminated paper, which is obtained by pasting these resin films on the surface of paper or by processing it with molten resin. A subbing layer or corona discharge processing may be applied to improve the adhesion between the resin surface and the ink receiver 1-.

When forming an ink-receiving layer on these supports by coating the entire pigment coating liquid, etc., a blade coater, an air knife coater, a roll coater, a plush coater, or a curtain coater, which are generally used as coating machines, can be used. ,
A bar coater, gravure coater, spray device, etc. are usually used.

Furthermore, when the support is paper, it is also possible to use a size press on a paper machine, a gut roll, a spray, etc.

A sheet simply provided with an ink-receiving layer on a support can be used as it is as a recording sheet according to the present invention, but the surface smoothness can be improved by heating it with a super calender or gloss calender and/or passing it through a roll nip under pressure. It is also possible to give In this case, the degree of processing may be limited because excessive processing by supercalendering will result in a total decrease in ink absorbency due to the voids between the particles that have been formed.

Measurements of various physical property values in Examples were performed in the following manner. First of all, Sharp @ inkjet printer (IO-70
0) The entire image was soaked in cyan (C) and magenta, and the image density before and after soaking was measured using a Mac Pes densitometer RD514, and the density after soaking was divided by the density before soaking as a measure of percentage water resistance. In addition, the solid image obtained in the same manner was measured using a xenon fade meter (F'AL-25 manufactured by Suga Tenken Iso Co., Ltd.).
X-HCL type) at 40℃, 60%, illuminance 63 & armpit 40
The color density before and after irradiation was measured with a Macbeth densitometer 1 (D514), and the percentage of the density before and after irradiation was used as a measure of total light resistance.The higher the value, the better the light resistance and water resistance. The dot diameter is a value calculated by measuring the area of a single dot in the black ink area of the same inkjet printer using a dot area meter, converting it to an area assuming a perfect circle, and calculating the diameter.It is the ink absorption rate. Using the same color image printer, the red printed area (macenta + yellow) was brought into contact with the paper presser roll immediately after solid printing (about 1 second later), and judged by whether or not stains appeared.Furthermore, ink absorption The ability was determined by the degree of bleeding at the boundary of the solid printed area of the same inkjet printer.

The present invention will be described below with reference to examples, but it is not limited to these examples. In addition, parts and percentages shown in Examples refer to parts and weight percentages of N.

Example 1 A cationic hydrated aluminum oxide was prepared in the following manner.

3 of aluminum sulfate m liquid with 8%AL20sk rich
130 parts and 26 parts of sodium aluminate Al 2
2080 parts of the 05 solution were simultaneously injected with stirring into 11,250 parts of water to precipitate the alumina hydrogel at pH 7-7.5. The pH was then adjusted to 10.5 by adding excess sodium aluminate, and the alumina hydrogel was washed with Fl-110.5).
IJum and sulfate were removed. This cake was diluted and filtered at pH 7-8 to reduce the sodium content to 0.1% or less.

The cake thus prepared was reslurried at a concentration of 10%, dried in a spray dryer at an inlet temperature of 180°,
A xerogel with an average secondary particle diameter of 4 μm was obtained. This xerogel had a pore volume of 1.04 m17't and a zeta potential of +28 mV when dispersed in water, and was a porous cationic water-containing aluminum oxide that could be used in the present invention.

As pigments, 80 parts of light rehydrated calcium acid (Uninoku-70, Shiraishi Kogyo Co., Ltd.), heavy calcium carbonate (Nisscalon 20) were used as pigments.
0, manufactured by Sankyo Kozue Powder) 20 parts, dispersant (Aron T520, manufactured by Toagosei Co., Ltd.) 0.1 part, Enika Shu Powder (M83800, Japan Foods #) 15 parts, cationic water conserving aluminum oxide prepared above 100 parts A coating solution with a concentration of 20% consisting of
The recording paper of Example 1 was obtained by smoothing the surface. Table 1 shows the evaluation results of the obtained recording paper.

Example 2 Cation water injection oroaluminum oxide was prepared in the following manner.

Aluminum nitrate water bath solution (8% as A120 g) 1
00f' diluted to 700 l of water and heated to 95°C with stirring.
It was heated to To this solution, 320 ft of sodium hydroxide was dissolved in a bath to adjust the pH to 11.0, and then aged for 60 minutes to produce an alumina hydrogel slurry. Next, an aqueous aluminum nitrate solution (8 as At203) was added to this slurry.
%) 400f? ! - The pH was adjusted to 4.5 and held for 5 minutes, and then sodium hydroxide was added again to adjust the pH to 4.5 to obtain an alumina hydrogel slurry.

This slurry was t-filtered, pressed, dried, crushed and classified to obtain an oxide powder with an average secondary particle size of 8 μm. When the pore distribution of this oxide was determined by mercury porosimetry, it had a pore peak at 300 A0 and a pore volume of 0.93 td/f. Further, when this was dispersed in pure water and the zeta potential gold was determined, it had a cationic charge of +34 mV.

Basis weight 781/lt? A coating solution consisting of 100 parts of the above-prepared cationic water-containing aluminum oxide and 15 parts of polyvinyl alcohol was applied to coated base paper with a Steckigt size degree of 21 seconds at a solid content of 15 f/r? The recording paper of Example 2 was obtained by applying the coating using an air knife coater, drying it, and smoothing the surface by passing it through a super calender. Table 1 shows the evaluation results of the obtained recording paper.

Comparative Example 1 Irrigation aluminum oxide (manufactured by Showa Denko, Ijirai) H by Bayer method of treating bauxite with caustic soda
2O, average secondary particle diameter - 10μ), and 15 parts of polyvinyl alcohol, the solid content was 15 f/l.
Basis weight 7B to make it ri? /n? The recording paper of Comparative Example 1 was obtained by coating the coated base paper with an air knife coater, drying it, and smoothing the surface by passing it through a super calender. Table 1 shows the evaluation results of the obtained recording paper.

Comparative Example 2 A comparative example was carried out in exactly the same manner as in Example 1, except that hydrated alumina for paper pigments (Hydralua 05 manufactured by Alcoa) was used instead of the cationic hydrated aluminum and mubaride prepared in Example 1. Two recording sheets were obtained. Table 1 shows the evaluation results of the obtained recording paper.

Table 1 From the results in Table 1, it is recognized that the recording paper of Example 1.2 using cationic water-containing aluminum oxide is excellent in both water resistance and light resistance.

Procedural amendment (0) Showa, FγDite Patent Application No. ’70079 No. 3
Relationship with the case of the person making the amendment Patent Applicant 4, Agent Address: 8, Mitsubishi Paper Mills Co., Ltd., 3-4-2 Marunouchi, Chiyoda-ku, Tokyo 100, Contents of the amendment (Reg. 11) 'Pigeon skin Riko Q ゛l Ji 1 power doctor 7゛l So important 5□1 cutting latitude 53゜

Claims (1)

[Claims] An inkjet recording medium comprising at least one ink-receiving layer provided on a support, the ink-receiving layer containing kg of porous cationic hydrated aluminum oxide.