JP2005126466A - Aqueous dye ink for inkjet and inkjet recording method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an aqueous dye ink for inkjet having high gloss and ozone gas resistance and lasting dispersion stability of the ink and an inkjet recording method not causing blur and bronzing using the ink. <P>SOLUTION: In the aqueous dye ink containing at least water, a dye and fine resin particles, the zeta potential of the fine resin particles dispersed in the aqueous dye ink is -10 to -40 mV and the total concentration of the alkali metal ions in the aqueous ink is 500-4,000 ppm. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a novel aqueous dye ink for ink jet and an ink jet recording method.

  In recent years, the progress of ink-jet technology has been remarkable, and the image quality has been called the silver salt photography level.

  Water-based dyes are mainly used for these inks for ink jet recording. Aqueous dyes are superior in terms of color developability and gloss to dispersed inks such as pigments, but are insufficient in terms of image storage stability such as ozone gas resistance. Further, when an image formed with an improvement in image quality is compared with a conventional silver salt photograph, the glossiness is still insufficient.

  JP-A-2001-187852 and JP-A-2002-240413 disclose the addition of a resin to the ink for the purpose of improving the ozone resistance of the aqueous dye ink. In addition, Japanese Patent Application Laid-Open Nos. 2002-80759, 2002-194253, 2002-285049, and Patent Document 1 (Japanese Patent Application Laid-Open No. 2003-55586) disclose techniques for adding latex or polymer fine particles to ink. Has been.

  The technique of adding latex or polymer fine particles to the ink described in the above publication has a certain effect on improving ozone gas resistance. However, when latex or polymer fine particles are added to the ink, an anion or cation charge is added to improve the dispersion stability, so the ink aggregates when ejected onto the medium (recording medium). cause.

  As a result, formation of a uniform film from the resin on the medium is hindered, and sufficient ozone gas resistance cannot be obtained. Although this phenomenon can be avoided by weakening the charge of the latex or polymer fine particles, the dispersion stability of the latex or polymer fine particles in the ink deteriorates, and the emission stability in the printer is impaired. Such deterioration of the emission stability is a major obstacle to speeding up the printer and improving the image quality.

  Furthermore, although the above publication does not mention improvement of glossiness by adding latex or polymer fine particles, sufficient performance can also be obtained with respect to glossiness due to aggregation of latex or polymer fine particles on the medium. Absent.

  JP-A-5-295212 and JP-A-11-199813 disclose that by reducing the amount of alkali metal ions in the ink, the liquid stability of the ink, the ejection stability from the printer, and the bleeding of the image are improved. And Patent Document 2 (Japanese Patent Laid-Open No. 2002-3765).

However, the alkali metal ion reduction technique described in the above publication is intended to improve the liquid stability of the ink when a specific color material is used, and is a resin dispersed in the ink. There is no description regarding the improvement of the stability of the fine particles, and no effective means has been found although the improvement of the stability of the resin fine particles is a big problem.
Japanese Patent Laid-Open No. 2003-55586 Japanese Patent Laid-Open No. 2002-3765

  The problems to be solved by the present invention are an aqueous dye ink for inkjet which has high glossiness and ozone gas resistance and does not cause deterioration of the dispersion stability of the ink, and an inkjet which does not cause bleeding or bronzing using the ink. It is to provide a recording method.

  As described above, the image quality of the ink jet recording image formed with the water-based dye ink has not yet reached that region as compared with the image quality of the silver salt photographic image, and has characteristics inferior in glossiness and ozone gas resistance. It was.

  By adding resin fine particles to the ink, it is possible to obtain a certain level of glossiness and ozone gas resistance, if not sufficient. However, even if this method is used, sufficient performance cannot be obtained. The reason is that the stability of the resin fine particles in the ink is insufficient, or the interaction with the cationic compound or polyvalent metal ion prevents the resin film from being uniformly formed on the media surface after output. This is probably because of this.

  As a result of diligent investigation regarding the factors, the zeta potential of the resin fine particles when dispersed in the aqueous dye ink is adjusted to the range of −10 to −40 mV, preferably −10 to −30 mV, and in the aqueous ink. It has been found that when the total concentration of alkali metal ions is 500 ppm or more and 4000 ppm or less, uniform glossiness and ozone gas resistance can be obtained, and further, dispersion stability of resin fine particles in the ink can be improved.

  Furthermore, by setting the amount of the cationic compound and the amount of polyvalent metal ions in the ink jet recording medium to a specific range, it is possible to provide an ink jet recording method that does not cause bleeding and bronzing using the ink. It has been found that the purpose and effect of the present invention can be further exerted by ejecting with a printer having a droplet amount in the range of 0.5 pl to 3.0 pl.

That is, it has been found that the object of the present invention is achieved by adopting any one of the following configurations.
(Claim 1)
In an aqueous dye ink containing at least water, a dye, and resin fine particles, the resin particles have a zeta potential of −10 to −40 mV when dispersed in the aqueous dye ink, and the total of alkali metal ions in the aqueous ink An aqueous dye ink for ink-jet, wherein the concentration is 500 ppm or more and 4000 ppm or less.
(Claim 2)
The aqueous dye ink for inkjet according to claim 1, wherein the zeta potential is -10 to -30 mV.
(Claim 3)
The aqueous dye ink for inkjet according to claim 1 or 2, wherein the total concentration of the alkali metal ions is 500 ppm or more and 3000 ppm or less.
(Claim 4)
The aqueous dye ink for inkjet according to any one of claims 1 to 3, wherein the composition of the resin fine particles is acrylic or polyurethane.
(Claim 5)
An ink jet recording medium having a void-type ink receiving layer on a support, wherein the total amount of the cationic polymer in the ink receiving layer is 0.2 g / m ² or more and 3.0 g / m ² or less. An ink jet recording method, wherein printing is performed with the aqueous dye ink described in any one of 1 to 4.
(Claim 6)
An ink jet recording medium having a void-type ink receiving layer on a support, wherein the total amount of polyvalent metal ions in the ink receiving layer is 0.1 g / m ² or more and 1.0 g / m ² or less. Item 5. An ink jet recording method comprising printing with the aqueous dye ink described in any one of Items 1 to 4.
(Claim 7)
An ink jet recording method, wherein the amount of droplets of the ink jet printer that discharges the aqueous dye ink according to any one of claims 1 to 4 is 0.5 pL or more and 3.0 pL or less.

  According to the present invention, there are provided an aqueous dye ink for inkjet which has high glossiness and ozone gas resistance and is not accompanied by deterioration of dispersion stability of the ink, and an inkjet recording method using the ink without causing bleeding or bronzing. Can do.

  Latex is generally stabilized by forming a protective layer around the particles with a surfactant or protective colloid, but when the protective layer is broken by mechanical or chemical action, it is dispersed and destroyed. Will be caused. One chemical action is due to electrolytes.

  For example, when an electrolyte is added to a latex stabilized with an anionic activator, the positive charge such as metal ions contained in the electrolyte neutralizes the particle charge and compresses the electric double layer formed by the activator. Therefore, aggregation occurs. In general, it is known that the stability of latex is improved by increasing the amount of surfactant during emulsion polymerization. In addition, the effective potential at the latex particle interface is considered to be substantially coincident with the zeta potential. Therefore, the dispersion stability of the latex containing an anionic activator improves as the zeta potential shows a more negative potential.

  However, such a negatively charged particle generally interacts with a cationic compound contained in the medium when emitted onto the medium, causing aggregation.

  According to the present invention, an ink jet recording method having high glossiness and ozone gas resistance can be achieved without deterioration of ink dispersion stability. At this time, the range of the zeta potential is −10 to −40 mV, preferably −10 to −30 mV. The method for measuring the zeta potential is not particularly limited, but can be performed using a commercially available measuring instrument such as ELS-800 (manufactured by Otsuka Electronics Co., Ltd.).

  As a means of adjusting the alkali metal ion concentration in the ink, alkali metal ions, heavy metal ions, etc. are removed by a method that uses ultrafiltration, treatment with ion exchange resin, electrodialysis, salting out, acid precipitation, etc. can do. In view of the stability of the ink, the smaller the amount of alkali metal ions, the better. However, in view of the cost of removing alkali metal ions and the viewpoint of production stability, the content of alkali metal ions is preferably 500 ppm to 4000 ppm, and 500 ppm to 3000 ppm. The following is more preferable.

  Each alkali metal ion can be quantified using, for example, ICP-AES (inductively coupled plasma emission analyzer SPS-4000 manufactured by Seiko Electronics Co., Ltd.).

  The resin fine particle dispersion according to the present invention includes resin particles dispersed in a medium, for example, water, and the resin fine particles are also called polymer fine particles or latex.

  The resin fine particles can be used in the form of an aqueous dispersion of various polymers. Specifically, acrylic, styrene-acrylic, acrylonitrile-acrylic, vinyl acetate, vinyl acetate-acrylic, vinyl acetate-vinyl chloride, polyurethane, silicone-acrylic, polyester, and epoxy Examples of the polymer include acrylic and urethane polymers.

  Usually, these resin fine particles are obtained by an emulsion polymerization method. The surfactants, polymerization initiators, etc. used there may be those used in conventional methods. Regarding the synthesis method of resin fine particles, U.S. Pat. Nos. 2,852,368, 2,853,457, 3,411,911, 3,411,912, 4,197,127, Belgian Patent Nos. 688,882, 691,360, 712,823, JP-B 45-5331, JP-A-60-18540, 51-130217, 58-137831, 55- 50240 and the like.

  The resin fine particles used in the ink according to the present invention preferably have an average particle size of 10 to 200 nm, more preferably 10 to 150 nm, and still more preferably 10 to 100 nm.

  If the average particle diameter of the resin fine particles is 10 nm or more, the resin fine particles do not penetrate into the void layer and are present on the surface of the void layer, which is preferable in terms of gloss. If the average particle size of the resin fine particles is 200 nm or less, the resin fine particles are small to some extent, which is advantageous from the viewpoint of leveling properties on the surface of the void layer, and is preferable in terms of gloss.

  The average particle size of the resin fine particles can be easily obtained using a commercially available particle size measuring device using a light scattering method or a laser Doppler method, for example, Zetasizer 1000 (manufactured by Malvern).

  In the ink according to the present invention, the content of the resin fine particles in the ink is preferably 0.2 to 10% by mass, and more preferably 0.5 to 5% by mass. If the addition amount of the resin fine particles is 0.2% by mass or more, a sufficient effect on the color fading property can be exhibited. If the addition amount is 10% by mass or less, the ink ejection property becomes more stable, and further during storage. This is more preferable because it can suppress an increase in ink viscosity.

  In the resin fine particles according to the present invention, the minimum film-forming temperature (MFT) is preferably −60 to 60 ° C. In the present invention, a film-forming aid may be added to control the minimum film-forming temperature of the resin fine particles. The film-forming aid, also called a plasticizer, is an organic compound (usually an organic solvent) that lowers the minimum film-forming temperature of the polymer latex. For example, “Synthetic Latex Chemistry (Souichi Muroi, published by Kobunshi Shuppankai (1970)” )"It is described in.

  In the present invention, there is no particular limitation on the method for imparting the zeta potential defined above to the resin fine particles.For example, by appropriately selecting the type and amount of the surfactant, the addition of an additive having a charge, etc. A desired zeta potential can be obtained. The zeta potential depends on the concentration of the fine particles when dispersed, the type of solvent, the ion concentration, etc. In the present invention, the zeta potential when the resin fine particles are dispersed in the ink is adjusted to a specified range. The effect is obtained.

  The ink jet recording medium according to the present invention preferably contains a cationic mordant.

  The cationic mordant is not particularly limited, but is preferably a cationic polymer or a polyvalent metal salt.

  As specific examples of the cationic polymer that can be used in the present invention, known polymers can be used. For example, polyethyleneimine, polyallylamine, dicyandiamide polyalkylene polyamine, a condensate of dialkylamine and epichlorohydrin. , Polyvinylamine, polyvinylpyridine, polyvinylimidazole, diallyldimethylammonium salt condensates, polyacrylic acid ester quaternized compounds, etc., among others, JP-A-10-193976, 10-217601, What is described in 11-20300 gazette etc. is preferable.

  In the present invention, the cationic polymer can be used without any particular limitation, but those having a weight average molecular weight of 2000 to 100,000 are particularly preferable.

  As the polymer mordant, a cationic polymer mordant having a primary to tertiary amino group and a quaternary ammonium base is used. However, there is little discoloration and deterioration of light resistance with time, and the mordant ability of the dye is sufficiently high. Therefore, a cationic polymer mordant having a quaternary ammonium base is preferable.

  The cationic polymer preferably used in the present invention is more preferably a polymer having a quaternary ammonium base, particularly preferably a homopolymer of a monomer having a quaternary ammonium base or other copolymerizable 1 or 2 It is a copolymer with the above monomers.

  Examples of the monomer having a quaternary ammonium base include the following examples.

  A monomer that can be copolymerized with a quaternary ammonium base is a compound having an ethylenically unsaturated group. For example, the following specific examples can be given.

  Specific examples of the cationic polymer preferably used in the present invention are shown below, but the present invention is not limited thereto.

  In particular, when the cationic polymer having a quaternary ammonium base is a copolymer, the ratio of the cationic monomer is usually 10 mol% or more, preferably 20 mol% or more, particularly preferably 30 mol% or more.

  The monomer having a quaternary ammonium base may be a single monomer or two or more types.

  Cationic polymers having quaternary ammonium bases are generally highly water soluble due to the quaternary ammonium bases, but are not sufficiently soluble in water depending on the composition and ratio of the monomer that does not contain the quaternary ammonium base to be copolymerized. However, it can be used in the present invention as long as it can be dissolved in a mixed solvent of a water-miscible organic solvent and water.

  Here, the water-miscible organic solvent means alcohols such as methanol, ethanol, isopropanol, and n-propanol, glycols such as ethylene glycol, diethylene glycol, and glycerin, esters such as ethyl acetate and propyl acetate, acetone, and methyl ethyl ketone. An organic solvent that can usually be dissolved in water by 10% or more, such as ketones and amides such as N, N-dimethylformamide. In this case, the amount of the organic solvent used is preferably equal to or less than the amount of water used.

  Here, the weight average molecular weight is a value converted into a polyethylene glycol value determined from gel permeation chromatography.

  When the cationic polymer solution is added to the surface anionic fine particle-containing dispersion, agglomerates may be generated vigorously. However, when the weight average molecular weight of the cationic polymer is 100,000 or less, Such a phenomenon is unlikely to occur, and therefore, it is easy to obtain a substantially uniform dispersion containing little coarse particles. Excellent glossiness can be expected from ink jet recording paper prepared using such a dispersion. From the same viewpoint, the weight average molecular weight is more preferably 50,000 or less.

  The lower limit of the weight average molecular weight is usually 2000 or more from the viewpoint of the water resistance of the dye.

  The ratio of the fine particles to the cationic polymer can vary depending on the kind of fine particles, the average particle diameter, the kind of the cationic polymer, or the weight average molecular weight. In the present invention, the ratio of the fine particles is replaced with the cationic surface. In order to stabilize, it is preferable that it is 1: 0.01-1: 1.

  Within the above range, the anion component of the fine particles is completely covered with the cation component, so that the anion portion of the fine particles and the cation portion of the cationic polymer may be ion-bonded to form coarse particles. Absent.

Specific examples of the polyvalent metal salt include sulfates such as Mg ²⁺ , Ca ²⁺ , Zn ²⁺ , Zr ²⁺ , Ni ²⁺ , and Al ³⁺ , chlorides, nitrates, acetates, etc. And preferably Mg ²⁺ , Zr ²⁺ , Al ³⁺ . In addition, inorganic polymer compounds such as basic polyaluminum hydroxide and zirconyl acetate are also included as examples of preferable water-soluble polyvalent metal compounds.

  The compound containing a zirconium atom used in the present invention excludes zirconium oxide, and specific examples thereof include zirconium difluoride, zirconium trifluoride, zirconium tetrafluoride, hexafluorozirconium salt (for example, Potassium salt), heptafluorozirconate (eg, sodium salt, potassium salt or ammonium salt), octafluorozirconate (eg, lithium salt), fluorinated zirconium oxide, zirconium dichloride, zirconium trichloride, zirconium tetrachloride , Hexachlorozirconate (for example, sodium salt and potassium salt), zirconium oxychloride (zirconyl chloride), zirconium dibromide, zirconium tribromide, zirconium tetrabromide, zirconium bromide oxide, zirconium triiodide, tetraiodine Zirconide Zirconium, zirconium peroxide, zirconium hydroxide, zirconium sulfide, zirconium sulfate, zirconium p-toluenesulfonate, zirconyl sulfate, sodium zirconyl sulfate, acidic zirconyl sulfate trihydrate, potassium zirconium sulfate, zirconium selenate, zirconium nitrate, nitric acid Zirconyl, zirconium phosphate, zirconyl carbonate, zirconyl ammonium carbonate, zirconium acetate, zirconyl acetate, zirconyl ammonium acetate, zirconyl lactate, zirconyl citrate, zirconyl stearate, zirconyl phosphate, zirconium oxalate, zirconium isopropylate, zirconium butyrate, Zirconium acetylacetonate, acetylacetone zirconium butyrate, zirconium stearate butyrate, di Benzalkonium acetate, bis (acetylacetonato) dichloro zirconium and tris (acetylacetonato) chloro zirconium, and the like.

  Among these compounds, zirconyl carbonate, zirconyl ammonium carbonate, zirconyl acetate, zirconyl nitrate, zirconyl oxychloride, zirconyl lactate and zirconyl citrate are preferable, particularly carbonic acid carbonate, from the viewpoint of further prominently preventing bleeding after printing. Zirconyl ammonium, zirconyl acid chloride, and zirconyl acetate are preferred. Specific examples of the trade names of the above compounds include zirconyl acetate ZA (trade name) manufactured by First Rare Earth Chemical Industries, and zirconyl oxychloride (trade name) manufactured by First Rare Earth Chemical.

  The compound containing an aluminum atom in the molecule that can be used in the present invention does not contain aluminum oxide. Specific examples thereof include aluminum fluoride, hexafluoroaluminic acid (for example, potassium salt), aluminum chloride, and basic. Aluminum chloride (eg, polyaluminum chloride), tetrachloroaluminate (eg, sodium salt), aluminum bromide, tetrabromoaluminate (eg, potassium salt), aluminum iodide, aluminate (eg, sodium salt) , Potassium salt, calcium salt), aluminum chlorate, aluminum perchlorate, aluminum thiocyanate, aluminum sulfate, basic aluminum sulfate, potassium aluminum sulfate (alum), ammonium aluminum sulfate (ammonium alum), sulfuric acid Thorium aluminum, aluminum phosphate, aluminum nitrate, aluminum hydrogen phosphate, aluminum carbonate, aluminum polysulfate silicate, aluminum formate, aluminum acetate, aluminum lactate, aluminum oxalate, aluminum isopropylate, aluminum butyrate, ethyl acetate aluminum diisopropylate, aluminum tris (Acetylacetonate), aluminum tris (ethylacetoacetate), aluminum monoacetylacetonate bis (ethylacetoacetonate), etc. can be mentioned.

  Among these, aluminum chloride, basic aluminum chloride, aluminum sulfate, basic aluminum sulfate, and basic aluminum sulfate silicate are preferable, and basic aluminum chloride and basic aluminum sulfate are most preferable.

  In the present invention, when the cationic polymer and the polyvalent metal salt are used, the addition amount is important.

When the cationic polymer is used, it is preferably used in the range of 0.2 to 3 g per 1 m ^{2 of} the recording medium. If it is less than 0.2 g / m ^{2, the} effect of suppressing density fluctuation due to the addition of resin fine particles to the ink is slightly weak, and the effect of suppressing bleeding and preventing ozone fading is also slightly weak. On the other hand, if it is more than 3 g / m ^{2, the} effect of suppressing density fluctuation due to the addition of resin fine particles to the ink is slightly weak, and the effect of preventing ozone fading is also slightly weak, and bronzing is likely to occur. In order to express the effect of the present invention more greatly, it is particularly preferable to use 1 to ² g / m ² of the cationic polymer.

When the polyvalent metal salt is used for the same reason, it is preferably used in the range of 0.1 to 1 g / m ² . In order to express the effect of the present invention more greatly, it is particularly preferable to use 0.4 to 0.8 g / m ² of the polyvalent metal salt.

  In the ink jet recording medium according to the present invention, it is preferable to use a curing agent. The curing agent can be added at any time during the production of the ink jet recording medium. For example, it may be added to the coating solution for forming the void layer.

  In the present invention, when a hardener is used, a method of supplying a water-soluble binder curing agent after forming the void layer may be used alone, but preferably the above-mentioned curing agent is used for void layer formation. It is to use together with the method of adding in the coating liquid.

  The curing agent that can be used in the present invention is not particularly limited as long as it causes a curing reaction with a water-soluble binder, but boric acid and salts thereof are preferable. In addition, known compounds can be used and are generally compounds having a group capable of reacting with a water-soluble binder or compounds that promote the reaction between different groups of a water-soluble binder. Depending on the case, it is appropriately selected and used. Specific examples of the curing agent include, for example, epoxy curing agents (diglycidyl ethyl ether, ethylene glycol diglycidyl ether, 1,4-butanediol diglycidyl ether, 1,6-diglycidyl cyclohexane, N, N-diglycidyl- 4-glycidyloxyaniline, sorbitol polyglycidyl ether, glycerol polyglycidyl ether, etc.), aldehyde curing agents (formaldehyde, glioxal, etc.), active halogen curing agents (2,4-dichloro-4-hydroxy-1,3,5) -S-triazine, etc.), active vinyl compounds (1,3,5-trisacryloyl-hexahydro-s-triazine, bisvinylsulfonylmethyl ether, etc.), aluminum alum and the like.

  Boric acid or a salt thereof refers to an oxygen acid having a boron atom as a central atom and a salt thereof, specifically, orthoboric acid, diboric acid, metaboric acid, tetraboric acid, pentaboric acid, and octaboron. Examples include acids and their salts.

  Boric acid having a boron atom and a salt thereof as a curing agent may be used alone or in combination of two or more. Particularly preferred is a mixed aqueous solution of boric acid and borax.

  The aqueous solutions of boric acid and borax can be added only in relatively dilute aqueous solutions, respectively, but by mixing them both can be made into a concentrated aqueous solution and the coating solution can be concentrated. Further, there is an advantage that the pH of the aqueous solution to be added can be controlled relatively freely.

  The total amount of the curing agent used is preferably 1 to 600 mg per 1 g of the water-soluble binder.

  Next, the configuration and effects of the present invention will be further described with reference to specific embodiments and their characteristics. Of course, it goes without saying that the embodiments of the present invention are not limited thereto.

(Preparation of dyes D-1 to D-3)
C. I. Sodium sulfate is added to an aqueous solution of Direct Red 227 to salt out the dye. Next, the deposited precipitate is collected by filtration, washed with a saturated aqueous solution of sodium sulfate, and then dried. A predetermined amount of the obtained dry solid is dissolved in a 3: 1 mixed solution of ethylene glycol and N-methyl-2-pyrrolidone, and then the solution is filtered to obtain a filtrate. Next, a predetermined amount of water is added to the obtained filtrate and stirred, and then passed through a cation exchange resin. The solution subjected to the cation exchange treatment was adjusted to an appropriate pH and then filtered and dried to obtain a dye D-1.

  Next, the dye D-1 is dissolved in ion-exchanged water, a predetermined amount of 1 mol / L NaOH aqueous solution is added, dried, and powdered to obtain a dye D-2 having the alkali metal ion amount shown in Table 1. It was.

  Next, in the preparation of the dye D-1, it was filtered and dried without passing through a cation exchange resin to obtain a dye D-3.

  Quantification of each alkali metal ion in the dye was performed using ICP-AES (inductively coupled plasma emission spectrometer SPS-4000 manufactured by Seiko Electronics Co., Ltd.).

(Production of polymer latex LX-1 to LX-8)
The flask was equipped with a stirring blade, a thermometer, a dropping funnel, a nitrogen introduction tube, and a reflux condenser, distilled water was added, and nitrogen gas was introduced to carry out deoxygenation and heated to an internal temperature of 70 ° C.

  As a premonomer, n-butyl acrylate was dropped into the flask. After dropping the pre-monomer, sodium dodecylbenzenesulfonate was added, and ammonium persulfate was further added as a polymerization initiator, and the temperature was kept at 70 ° C. While stirring, n-butyl acrylate was dropped into the flask from the dropping funnel 10 minutes after the addition of ammonium persulfate.

  Meanwhile, the temperature rising by the polymerization heat was controlled and kept at 70 ° C., and the polymerization was continued as it was for 5 hours after the completion of the dropping, and then the polymerization product was cooled to 25 ° C. to obtain a polymer latex LX1. In the method for producing LX1, the monomer composition and the surfactant amount were changed as shown in Table 2 to produce polymer latexes LX-2 to LX-8.

(Preparation of magenta ink I-1)
Magenta dye D-1 2 parts by weight Polymer latex LX-1 (in terms of solid content) 1.1 parts by weight Ethylene glycol 20 parts by weight Diethylene glycol 10 parts by weight Deionized water 40 parts by weight After mixing and stirring the above compositions, A magenta ink I-1 having a resin particle concentration of 1.5% was prepared by filtration through a filter having a filtration diameter of 1 μm.

  Similarly, magenta inks I-2 to I-10 were prepared by combinations of dyes and polymer latexes shown in Table 3.

(Measurement of zeta potential of resin fine particles in ink)
The zeta potentials of I-1 to I-10 prepared above were measured using ELS-800 (manufactured by Otsuka Electronics Co., Ltd.), and the results are shown in Table 3.

<< Preparation of inkjet recording medium >>
(Preparation of recording media M-1 to M-5)
On a resin-coated base paper having a thickness of about 220 μm, coating liquids comprising the components shown in Table 4 were prepared so as to have the weights shown in Table 4, and then coated to prepare recording media M-1 to M-5. .

  An appropriate amount of a surfactant and boric acid were added to each coating solution. Each produced recording medium was processed into a roll paper having a width of 12.7 cm.

  The details of each additive described in Table 4 are as follows.

Inorganic fine particles: Gas phase method silica (primary average particle diameter 7 nm)
Binder: Polyvinyl alcohol (PVA235 manufactured by Kuraray Co., Ltd.)
Cationic polymer: P-1
Multivalent metal salt: Water-soluble basic aluminum

All figures in the table are g / m ²
<Inkjet image recording>
The voltage applied to the nozzle system and the piezoelectric element of the ink jet recording head can be appropriately changed to adjust the ink droplet amount per one ejection operation. Using this recording head, a magenta ink jet recording apparatus equipped with each of the prepared magenta inks was used to produce a magenta solid image with a combination of magenta ink, ink droplet amount, and media type shown in Table 5, manufactured by Konica. Printed on Konica Photo IJ QP paper.

<Evaluation of inkjet image>
(Glossy)
The magenta wedge image was measured for the reflection density at each stage of the wedge using an optical densitometer (X-Rite 938 manufactured by X-Rite). The 60 ° gloss value was measured using a goniophotometer (manufactured by Nippon Denshoku Industries Co., Ltd.), and the value is shown in Table 5. The larger the value, the higher the glossiness.
(Ozone gas resistance)
After the magenta wedge image was exposed to an environment having an ozone concentration of 50 ppm at 23 ° C. for 120 minutes, the reflection density before and after exposure of the portion showing the reflection density 0.5 and 1.5 of the wedge image was measured before the exposure. Measured in the same manner as above, and the fading rate was determined according to the following formula. The closer the value is to 100%, the better the ozone gas resistance.

Fading rate = (reflection density after exposure) / (reflection density before exposure) × 100 (%)
The glossiness and ozone gas resistance characteristics are desirably 80 or more, less than 80 is not practically preferable, and apparently practically problematic in the 60s.
(Ink emission)
The occurrence of discharge unevenness (image defects such as streak unevenness) was visually evaluated according to the following criteria.
Evaluation 5: Discharge unevenness does not occur with continuous 500 sheets Evaluation 4: Discharge unevenness does not occur with 400 continuous sheets, but occurs afterwards Evaluation 3: Discharge unevenness does not occur with 300 continuous sheets, but occurs afterwards Evaluation 2: Continuous 200 sheets No discharge unevenness occurs, but subsequent occurrence evaluation 1: No discharge unevenness occurs after 100 consecutive sheets, but occurs later Evaluation 4 has no practical problem, but characteristics of evaluation 3 or lower may cause a problem And the lower the evaluation value, the higher the possibility of a problem.
(Bleeding)
A sample of an image printed in an environment of 25 ° C. and 50% RH is visually observed for the bleeding state after being stored for one week in an environment of 40 ° C. and 80% RH, and the bleeding resistance is evaluated according to the following criteria. went.

5: Smudge was not observed 4: Slight bleed was observed but almost no problem 3: Smear was observed but within the allowable range 2: Smear was observed 1: Smear was very large (occurrence of bronzing) )
A magenta solid image was printed by the above method, and the presence or absence of bronzing was visually observed.

  From Table 5, by adjusting the zeta potential in the aqueous dye ink containing resin fine particles from -10 mV to -40 mV and the total concentration of alkali metal ions in the range of 500 ppm to 4000 ppm, the ink due to the deterioration of the ink dispersion stability It can be seen that high glossiness and ozone gas resistance can be achieved without deterioration of the light emission. In addition, by adjusting the amount of the cation polymer and polyvalent metal ion in the inkjet recording medium to a specified range, the effect of the present invention can be obtained without blurring or bronzing, and the droplet volume of the printer is specified. It can be seen that by adjusting to this range, more preferable performance can be obtained with respect to ink emission properties, glossiness and ozone gas resistance.

Claims (7)

In an aqueous dye ink containing at least water, a dye, and resin fine particles, the resin particles have a zeta potential of −10 to −40 mV when dispersed in the aqueous dye ink, and the total of alkali metal ions in the aqueous ink An aqueous dye ink for ink-jet, wherein the concentration is 500 ppm or more and 4000 ppm or less. The aqueous dye ink for inkjet according to claim 1, wherein the zeta potential is -10 to -30 mV. The aqueous dye ink for inkjet according to claim 1 or 2, wherein the total concentration of the alkali metal ions is 500 ppm or more and 3000 ppm or less. The aqueous dye ink for inkjet according to any one of claims 1 to 3, wherein the composition of the resin fine particles is acrylic or polyurethane. An ink jet recording medium having a void-type ink receiving layer on a support, wherein the total amount of the cationic polymer in the ink receiving layer is 0.2 g / m ² or more and 3.0 g / m ² or less. An ink jet recording method, wherein printing is performed with the aqueous dye ink described in any one of 1 to 4. An ink jet recording medium having a void-type ink receiving layer on a support, wherein the total amount of polyvalent metal ions in the ink receiving layer is 0.1 g / m ² or more and 1.0 g / m ² or less. Item 5. An ink jet recording method comprising printing with the aqueous dye ink described in any one of Items 1 to 4. An ink jet recording method, wherein the amount of droplets of the ink jet printer that discharges the aqueous dye ink according to any one of claims 1 to 4 is 0.5 pL or more and 3.0 pL or less.