JP2011251503A - Ink set for ink jet recording, and recording method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an improved ink for ink jet recording where water resistance and light resistance are high, color bleed, feathering, and offset are reduced, and a clear image can be acquired at high density, and to provide an ink jet recording method using the ink.SOLUTION: In this ink jet recording method, previous addition of pretreatment liquid to a medium to be recorded is performed by a process of selectively injecting the pretreatment liquid to a contact region with the ink for recording. The pretreatment liquid contains polyvalent metal salt or cationic substance in a medium for pretreatment liquid. The ink contains at least a pigment as a coloring agent and water-soluble resin in a liquid solvent for ink composed of water and a water-soluble organic solvent. The water-soluble resin contains acetoacetyl modified polyvinyl alcohol or carboxyl modified polyvinyl alcohol.

Description

  The present invention relates to an ink set requiring ink jet recording and a recording method, and in particular, improved ink jet recording without feathering, excellent in quick-drying, capable of high-speed printing regardless of high image density, and free from color bleeding and smearing. The present invention relates to an ink set and a recording method.

  Since the ink jet recording method is relatively easy to increase in color, increase in density, and increase in recording speed, the recording apparatus is used in various aspects including personal use purposes and home use purposes. As an ink applied to such an ink jet recording system, inks containing various colorants in water or a hydrophilic medium composed of water and an organic solvent are frequently used. As a colorant, a solution obtained by dissolving a water-soluble dye in a hydrophilic medium has been used for a long time since it can be relatively easily prepared into an ink composition having a desired concentration and the color tone of a recorded image is good. However, since there are inevitable problems such as fading of printed matter over time and low water resistance of recorded images derived from the attribute of water solubility of dyes, recently, pigments dissolved in hydrophilic media have been replaced instead. Although it has been attracting attention and is actually on the market, the relative advantages and disadvantages of pigment inks have been discussed more than before. I will not discuss it. However, there are still many problems to be solved regarding relative difficulties such as finer pigment particles, dispersion stability in the ink medium, image density and color tone at the time of color mixing.

As a combination of the ink and the recording medium, the ink droplets ejected from the recording head are quickly absorbed into the inside, and there is no contamination such as smear due to residual liquid on the surface or due to transfer to the components of the recording apparatus, For example, a dedicated recording medium has been developed and used for the purpose of, for example, obtaining a clear image with high density and robustness. The attribute has been discussed much more than before, so as in the case of ink, here we avoid duplication and will not discuss it again in general, but these inks and dedicated recording media are expensive. In addition, it is avoided in the office field especially from the viewpoint of the handwriting and texture of the recorded material, and the use of plain paper such as PPC paper. Over's is strong.
When such a conventional ink jet recording ink is used for recording on such a non-dedicated recording medium, there are the following problems.

  That is, there is a problem of dirt such as smear of the recorded image and dirt due to transfer to parts of the recording apparatus such as a conveyance roller, and colorants such as dyes used in the ink penetrate into the paper together with the ink solvent. For this reason, coloring by the colorant is insufficient. Or, when water-based ink is absorbed inside the paper, bleeding occurs along the fibers constituting the paper, so that the ink dots become excessively large, or the outer periphery of the ink dots has an irregular shape such as jagged edges. Or so-called feathering occurs, and a clear recorded image cannot be obtained. In particular, when a color image is obtained, the inks of a plurality of colors are superimposed one after another before fixing, so that in the strengthened portion of the different color image, the color is blurred or mixed unevenly, so-called bleeding. A phenomenon occurs and a satisfactory image cannot be obtained.

  In order to solve such a problem, Japanese Patent Application Laid-Open No. 5-202328 of Patent Document 1 discloses an inkjet ink using a dye having a carboxyl group after applying a polyvalent metal salt as a chelating agent to a recording medium. Japanese Patent Application Laid-Open No. 6-106735 (Patent Document 2) describes a color ink containing a salt and a black ink that thickens due to the action of the salt. In addition, JP-A-3-240557 of Patent Document 3 and JP-A-3-240558 of Patent Document 4 disclose two liquids for improving image fastness. Although an ink jet recording method for printing is described, water-soluble dye inks are inherently poor in light resistance, as described above, and these techniques also provide image fastness. Te, further improvement is desired.

Japanese Patent Application Laid-Open No. 2007-162003 of Patent Document 5 discloses an image having improved water resistance and fixability to a recording medium without occurrence of beading and color bleeding on a recording medium having a low water absorption capability. In order to obtain a photo-crosslinkable side chain that can be cross-linked between side chains by irradiation of active energy rays to the main chain of a saponified product of colorant, water, and polyvinyl acetate, and an acetoacetyl group that can react with the cross-linking agent And an ink-jet ink containing a polymer compound having a thermally reactive side chain comprising at least one group selected from carboxyl groups.
This technique is an ink jet ink containing a polymer compound having a thermally reactive side chain composed of at least one group selected from an acetoacetyl group and a carboxyl group. However, it is a fixing mechanism that utilizes cross-linking between side chains of the polymer compound by irradiation of active energy rays, and means that require a drying process (such as a heater) can cause transfer stains to the conveyance rollers described above. Even if improvements such as color bleed are achieved, system problems such as high cost and increased environmental load due to complicated printing systems cannot be solved.
The conventional pretreatment method for aggregating the colorant discharged on the surface of the recording medium cannot sufficiently fix the agglomerated pigment (image) even if a high image density can be achieved. During such high-speed conveyance, a large amount of transfer contamination occurs on a conveyance roller or the like, and there is a problem that the effect of improving color bleeding and feathering is insufficient.

In the ink-jet recording method that prints two liquids first, we can obtain a clear image with fast ink drying even when printing on plain paper, and with high density and water resistance. As a recording technique for obtaining an image excellent in light resistance, a colorless or light-colored liquid composition containing a water-soluble polymer or a polyvalent metal salt is discharged onto a recording medium by coating or spraying means prior to recording. And then ejecting the recording liquid onto the recording medium to which the liquid composition is adhered by the ejecting means, wherein the recording liquid contains at least a colorant, a resin emulsion, and a water-soluble solvent. recording method in which, and the absorption coefficient measured by a dynamic scanning absorption liquid apparatus for said recording medium, a main configuration that is ^{3ml / (m 2 · m sec} ) 1/2 or more The recording technology including, but already proposed in JP 2002-211106 JP-Patent Document 6, the present invention, according to one aspect, corresponds to that further improve the recording technology.

An object of the present invention is to improve the fixability of an inkjet recording image, increase the density of the image, reduce color bleeding, and feathering.
That is, an object of the present invention is an improved ink jet recording ink that is excellent in water resistance and light resistance, has reduced color bleeding, feathering, and setback, and can obtain a clear image at a high density, and An object of the present invention is to provide an ink jet recording method using this.

The above-mentioned object is satisfactorily achieved by the following inkjet recording methods (1) to (12) and an inkjet recording ink set.
(1) “In an ink jet recording method in which an ink jet recording ink is ejected onto a recording medium to which a pretreatment liquid has been applied in advance and printed and recorded, the pretreatment liquid is preliminarily applied to the recording medium. Is applied by a step of selectively ejecting a pretreatment liquid to a contact area with the recording ink, and the pretreatment liquid contains a polyvalent metal salt or a cationic substance in the pretreatment liquid medium. The ink contains at least a pigment as a colorant and a water-soluble resin in an ink liquid medium composed of water and a water-soluble organic solvent, and the water-soluble resin is acetoacetyl-modified. An inkjet recording method comprising polyvinyl alcohol or carboxyl-modified polyvinyl alcohol ”.
(2) “The inkjet recording method according to (1) above, wherein the pigment of the recording ink is composed of an aqueous dispersion of water-insoluble vinyl polymer particles”.
(3) The above-mentioned (1), wherein the pretreatment liquid is an inkjet pretreatment liquid, and the polyvalent metal salt or the cationic substance is dissolved in a liquid medium for the pretreatment liquid. Or inkjet recording method according to item (2).
(4) “The inkjet recording method according to item (3), wherein the liquid medium for the pretreatment liquid is water or a mixture of water and a water-soluble organic solvent”.
(5) The inkjet recording method according to item (4), wherein the liquid medium for pretreatment liquid has a higher water content ratio than the liquid medium for ink.
(6) “The inkjet recording method according to any one of (1) to (5) above, wherein the recording medium is plain paper”.
(7) “Inkjet recording ink set comprising a combination of a pretreatment liquid previously applied to a recording medium and an inkjet recording ink subsequently ejected onto the recording medium, wherein the pretreatment liquid is , A polyvalent metal salt or a cationic substance is contained in the pretreatment liquid medium, and is selectively applied to the contact area with the recording ink by inkjet ejection, and the ink contains at least water. A liquid medium for ink comprising a water-soluble organic solvent contains a pigment as a colorant and a water-soluble resin, and the water-soluble resin contains acetoacetyl-modified polyvinyl alcohol or carboxyl-modified polyvinyl alcohol. Ink set for ink jet recording ".
(8) “The ink set for ink-jet recording according to item (7), wherein the pigment of the recording ink is composed of an aqueous dispersion of water-insoluble vinyl polymer particles”.
(9) “Ink set for ink-jet recording according to item (7) or (8) above, wherein the ink set is dissolved in a liquid medium for pretreatment liquid”.
(10) The ink set for ink jet recording according to (9), wherein the liquid medium for the pretreatment liquid is water or a mixture of water and a water-soluble organic solvent.
(11) The ink set for ink jet recording according to (10), wherein the liquid medium for pretreatment liquid has a higher content ratio of water than the liquid medium for ink.
(12) “The ink set for ink jet recording according to any one of items (7) to (11), wherein the recording medium is plain paper”.

  As is clear from the following detailed and specific description, according to the present invention, the water resistance and light resistance are excellent, color bleeding, feathering, and set-off are reduced, and the fixability of the inkjet recorded image is improved. An extremely excellent effect of providing an ink jet recording method capable of obtaining a high density image and obtaining an image with reduced color bleeding and feathering, and an ink set for ink jet recording therefor is exhibited.

FIG. 3 is a perspective explanatory view showing a state in which a cover of an example of an ink cartridge loading unit of the ink jet recording apparatus that can be used in the present invention is opened. It is a schematic block diagram explaining the whole structure of the said inkjet recording device example. It is a schematic enlarged view which shows an example of the inkjet head of this invention.

In order to reduce color bleeding, feathering, and setback in an inkjet printed image, the present inventors have used a polyvalent metal salt or a cationic substance and acetoacetyl-modified polyvinyl alcohol or carboxyl-modified polyvinyl alcohol as a water-soluble resin. The combination is particularly excellent with respect to the cohesiveness of the ink. However, when this combination is used, it has been found that it should be used in a specific mode, and further studies have been made based on this finding to arrive at the present invention.
Hereinafter, the present invention will be described in detail and specifically.

[Pretreatment method]
In the present invention, as described above, the pretreatment liquid containing the polyvalent metal salt and / or the cationic substance is selectively applied only to the contact area of the recording medium with the recording ink, and then is applied to the area. Printing is performed by ejecting a recording ink, and it is desirable to apply ink jet for the selective application.
It is possible to reduce costs by preventing overcoating and reducing the amount of pretreatment liquid used. There is also a description that there is a concern that the ink-jet recording of the pretreatment liquid on the printing site (area) has a low density and low viscosity, and eventually the adhesion amount must be increased and the cockling and fixing effect may not be exhibited. In fact, the whole application with a roller allows higher concentration, higher viscosity, and lower adhesion amount. The risk is higher than ink jet recording only on the part. On the other hand, according to the present invention, such a risk can be avoided.

[Pretreatment liquid]
(Polyvalent metal salt)
The polyvalent metal salt in the present invention is composed of divalent or higher polyvalent metal ions and anions bonded to these polyvalent metal ions, and is soluble in water. Specific examples include Ca ⁺⁺ , Cu ⁺⁺ , Ni ⁺⁺ , Mg ⁺⁺ , Zn ⁺⁺ , and Ba ⁺⁺ . In addition, Al ⁺⁺⁺⁺ , Fe ⁺⁺⁺⁺ , and Cr ⁺⁺⁺⁺ can also be used. Representative and preferred anions that bind to these cations include Cl ⁻ , NO ₃ ⁻ , I ⁻ , Br ⁻ , ClO ₃ ⁻ , and CH ₃ COO ⁻ .

(Cationic substance)
Examples of the cationic substance in the present invention include those having the following cationic sites. Of these, those having two or more such cationic sites are preferably used.

For example, ethylenediamine, diethylenetriamine, tetramethylenediamine, hexamethylenediamine, paraphenylenediamine, urea, polyallylamine, polyethyleneimine and the like can be mentioned.
Also, cationic polymers such as polyvinylpyridinium halide, polyvinylbenzyltrimethylammonium halide, polyethyleneimine, dicyandiamide formalin condensate, epichlorohydrin-modified polyalkylamine, polyethyleneimine quaternary ammonium salt, and quaternary ammonium group are copolymerized. Quaternary ammonium salts and polyamines such as acrylic and methacrylic acid ester copolymers included as monomers can be mentioned, and in particular, tertiary or quaternary ammonium salts and the like can be mentioned. Commercially available products include Sunstat E-818, Sunstat 1200, Sunfix 70, Cellopor YM-500 (above Sanyo Kasei), Pulset (Meisei Chemical), Jetfix (Satorita Chemical), Sumirez Resin 1001, Sumirez Resin FR-2P (Sumitomo Chemical), Neofix (Nikka Chemical), and the like.

  The above polyvalent metal salt and / or cationic substance is effective depending on whether it is used alone or in combination, and depending on the liquid medium composition for the pretreatment liquid and the amount of other additives. In order to obtain the above, it is desirable to contain 0.1 to 40%, preferably 1 to 30%, more preferably 3 to 15% on a mass basis.

(Liquid medium for pretreatment liquid; water-soluble organic solvent)
As the liquid medium for the pretreatment liquid, water or a mixed medium of water and a water-soluble organic solvent is preferably used. The water-soluble organic solvent, due to its main role, improves the wettability to prevent clogging of the nozzles of the injection head due to drying, and improves the wettability between the pretreatment liquid and the recording medium, and adjusts the penetration rate. However, wetting agents often have penetrability (conversely penetrants also have wettability), and these are cationic substances. Some have the effect of promoting solubility in the pretreatment liquid.
As the wetting agent, ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, polyethylene glycol, propylene glycol, 1,3-butanediol, 1,3-propanediol, 2-methyl-1,3-propanediol, 1 , 4-butanediol, 1,5-pentanediol, 1,6-hexanediol, glycerin, 1,2,6-hexanetriol, 2-ethyl-1,3-hexanediol, 1,2,4- Polyhydric alcohols such as butanetriol, 1,2,3-butanetriol, petriol, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol Polybutyl alcohol alkyl ethers such as dimethyl monobutyl ether, triethylene glycol monobutyl ether, tetraethylene glycol monomethyl ether, propylene glycol monoethyl ether, polyhydric alcohol aryl ethers such as ethylene glycol monophenyl ether and ethylene glycol monobenzyl ether Nitrogen-containing heterocyclic compounds such as N-methyl-2-pyrrolidone, N-hydroxyethyl-2-pyrrolidone, 2-pyrrolidone, 1,3-dimethylimidazolidinone, ε-caprolactam; formamide, N-methylformamide, formamide Amides such as N, N-dimethylformamide; monoethanolamine, diethanolamine, triethanolamine, monoethylamine, diethylamine, triethylamine And the like, sulfur-containing compounds such as dimethyl sulfoxide, sulfolane and thiodiethanol, propylene carbonate, ethylene carbonate, γ-butyrolactone, etc., and penetrants include diethylene glycol monophenyl ether, ethylene glycol Alkyl and aryl ethers of polyhydric alcohols such as monophenyl ether, ethylene glycol monoallyl ether, diethylene glycol monophenyl ether, diethylene glycol monobutyl ether, propylene glycol monobutyl ether, tetraethylene glycol chlorophenyl ether, polyoxyethylene polyoxypropylene block copolymer Nonionic surfactants such as coalescence, fluorosurfactants, lower alcohols such as ethanol and 2-propanol Le, in particular diethylene glycol monobutyl ether are preferred.

Among these water-soluble organic media, the wetting agent is preferably 10 to 50% by mass, more preferably 20 to 35% by mass in the liquid medium for the pretreatment liquid. If the content is too small, the nozzle is likely to be dried and defective ejection of droplets may occur. If the content is too large, the ink viscosity is increased, and the proper viscosity range may be exceeded. Further, the penetrant is preferably 0.1 to 20% by mass, and more preferably 0.5 to 10% by mass.
In the pretreatment liquid, the content ratio of the water-soluble organic solvent (wetting agent + penetrating agent) is 20.5 to 60% by mass, which is generally lower than the liquid medium for ink ( It is preferable that the water content ratio is high. The surface tension of the pretreatment liquid is preferably lower than that of the ink composition despite the small amount of water-soluble organic solvent such as a penetrant. It is desirable that the pretreatment liquid already exists in at least the expansion range of the ink droplets to be ejected later. To that end, it is possible to increase the application amount, but the application of the pretreatment liquid may be considered. This is because increasing the amount of ink more than the amount of ink applied causes problems such as adjustment of the ink jet device, increase in the capacity of the cartridge for applying more ink, and increase in application time. A surfactant may be added to adjust the surface tension. Specific examples thereof include amphoteric surfactants and nonionic surfactants that are the same as those in the ink composition, and more preferably, cationic surfactants such as benzalkonium chloride are used.

(Other additives)
In the pretreatment liquid, acid, antioxidant and oxygen absorber (especially effective for the prevention of polyamine oxidation in the case of pretreatment liquid), surfactant, and nozzle clogging prevention, if necessary or desired. Other additives such as an agent (saccharide), an antioxidant, an oxygen absorbent, a surfactant, an antiseptic or an antifungal agent, a rust inhibitor, and a pH buffer can be contained. Since many of these other additives can be used in the same manner in the case of ink, they will be described collectively in the detailed description of the ink.

<Acid>
The acid in the present invention plays a role of improving the adsorptivity with polyvinyl alcohol in the ink and adjusting the viscosity of the pretreatment liquid. As the acid, inorganic acids such as hydrochloric acid, sulfuric acid, sulfurous acid, nitric acid, nitrous acid, phosphoric acid, boric acid and carbonic acid, and organic acids such as carboxylic acid and sulfonic acid, amino acids and phenolic hydroxy compounds can be used. Nitric acid, sulfuric acid, phosphoric acid, acetic acid, formic acid, oxalic acid, lactic acid, citric acid, maleic acid, malonic acid, and other acids having a primary dissociation constant pKa of 5 or less in water are particularly excellent in adsorptivity to polyvinyl alcohol. It can be used suitably.
The mixing ratio of the acid to the polyvalent metal salt and / or the cationic substance in the pretreatment solution is not particularly limited, but is 200: 1 to 5: 1, more preferably 150: 1 on a weight basis. From the viewpoint of improving the adsorptivity to the polyvinyl alcohol surface contained in the ink, it is preferable that the ratio is ˜8: 1.

[ink]
As described above, the ink-jet ink in the present invention includes at least a pigment as a colorant and a water-soluble resin in an ink liquid medium composed of water and a water-soluble organic solvent. It contains acetoacetyl-modified polyvinyl alcohol or carboxyl-modified polyvinyl alcohol, but other water-soluble or water-dispersible resins (for example, so-called latex resins), surfactants, nozzles, as necessary or desired Other additives such as anti-clogging agents (saccharides), antioxidants and oxygen absorbers, surfactants, antiseptics and fungicides, rust preventives, pH buffering agents and the like can be contained.

(Water-soluble organic solvent)
As the water-soluble organic solvent in the ink of the present invention, those described in the pretreatment liquid are the same as in the case of conventional ink-jet inks, taking into consideration the injection property, the ability to prevent nozzle drying, and the permeability to the recording medium. Can be used.

(Acetoacetyl-modified polyvinyl alcohol, carboxyl-modified polyvinyl alcohol)
As shown in the following formula, acetoacetyl-modified polyvinyl alcohol is obtained by acetoacetylating polyvinyl alcohol with diketene, and carboxyl-modified polyvinyl alcohol is obtained by saponifying a copolymer of vinyl acetate and fumaric acid or maleic acid. is there. In these cases, the side chain acetyl group is usually not completely saponified, some (usually about 1.3 to 20% by number) acetyl groups remain, and the OH group is not completely acetoacetylated. Some OH groups remain.

As described above, since acetoacetyl-modified polyvinyl alcohol and carboxyl-modified polyvinyl alcohol in the present invention are rich in OH groups, COOH groups, CO groups, etc., they tend to gel in the presence of an acid. It is expected to be remarkably increased by reacting with the polyvalent metal salt and / or the cationic substance in the treatment liquid. Therefore, it is considered that the fixability of the printed image is improved and the abrasion resistance of the printed matter is improved.
In the present invention, the addition amount of acetoacetyl-modified polyvinyl alcohol and / or carboxyl-modified polyvinyl alcohol is preferably 10% by mass or more with respect to the total amount of the ink, and is 15% by mass or more from the viewpoint of improving glossiness. More preferred. When the content is less than 10% by mass, the image quality improvement effect cannot be obtained sufficiently.

(Colorant; Pigment)
<Black pigment>
As the pigment of the ink in the present invention, both for monochrome images and for color images can be used.
For example, as the black pigment used in the present invention, carbon black having a primary particle diameter of 40 nm or less, more preferably 30 to 10 nm is used. When the primary particle diameter is 40 nm or more, the original carbon black itself has low coloring power, and the optical density (reflection density) of the recorded matter is lowered. In the present invention, a specific functional group on the surface of such raw material carbon black is chemically bonded to give a positive or negative charge in water, and this charge can be dispersed and stabilized in the form of fine particles. .
Alternatively, wet oxidation may be performed in water using hypohalous acid and / or a salt thereof. Specific examples of hypohalous acid and / or a salt thereof include sodium hypochlorite and potassium hypochlorite, and sodium hypochlorite is particularly preferable from the viewpoint of reactivity. In the oxidation reaction, carbon black and hypohalite (for example, sodium hypochlorite) are charged in an appropriate amount of water for 5 hours or more, preferably about 10 to 15 hours, 50 ° C. or more, preferably 95 to 105 ° C. And stirring. At that time, the carbon black is preferably oxidized in a finely dispersed state.
The particle diameter of finely dispersed carbon black in the aqueous pigment ink composition of the present invention is 500 nm or less, and more preferably 50 to 200 nm. When the particle size of the carbon black is 50 nm or less, there is a case where the recorded matter is transparent and a sufficient optical density cannot be obtained. On the other hand, if it exceeds 500 nm, the carbon black tends to settle.
In general, fine dispersion is performed by wet grinding in an aqueous medium for 3 to 10 hours using a mill medium and a grinding apparatus. As the mill medium, glass beads, zirconia beads, magnetic beads or the like are used. Examples of the pulverizer include a ball mill, an attritor, a fourojet mixer, an impeller mill, a colloidal mill, and a sand mill (for example, a bead mill, a sand glider, a super mill, an agitator mill, and a dyno mill (trade name)).
The pigment preferably used in the present invention can be obtained, for example, by the method described in JP-A-8-3498. Commercially available products may be used as the pigment, and preferred examples include CAB-O-JET200, 300, IJX-181, 157, 164 manufactured by Cabot Specialty Chemicals Inc. Examples include Microjet CW1 or 2 manufactured by company, KM-9036 manufactured by Toyo Ink Co., Ltd., and the like.

<Color pigment>
A color pigment can also be used as the pigment of the present invention. Examples of color pigments include C.I. as pigments used in yellow ink. I. Pigment Yellow 1, C.I. I. Pigment Yellow 2, C.I. I. Pigment Yellow 3, C.I. I. Pigment Yellow 13, C.I. I. Pigment Yellow 16, C.I. I. Pigment Yellow 83, pigments used as magenta inks include C.I. I. Pigment Red 5, C.I. I. Pigment Red 7, C.I. I. Pigment Red 12, C.I. I. Pigment Red 48 (Ca), C.I. I. Pigment Red 48 (Mn), C.I. I. Pigment Red 57 (Ca), C.I. I. Pigment Red 112, C.I. I. Pigment Red 122, pigments used as cyan ink include C.I. I. Pigment Blue 1, C.I. I. Pigment Blue 2, C.I. I. Pigment Blue 3, C.I. I. Pigment Blue 15: 3, C.I. I. Pigment Blue 16, C.I. I. PigmentBlue 22, C.I. I. Vat Blue 4, C.I. I. Vat Blue6 etc. are mentioned. Such a pigment is added to the recording liquid in the range of 1 to 10% by weight. When the addition amount is less than 1%, the image density is not sufficient, and when it exceeds 10%, the viscosity of the recording liquid increases and the ejection stability may decrease.
These colorants are preferably pigments constituted by an aqueous dispersion of water-insoluble vinyl polymer particles.

<Polymerized pigment>
That is, in the recording liquid according to the present invention, a thermoplastic resin emulsion having an anionic charge is preferably added as a resin emulsion. The resin emulsion used in the present invention is made of a thermoplastic resin, and is preferably solid at a normal use temperature. The glass transition temperature (Tg) is preferably higher than room temperature, but the minimum film-forming temperature (MFT). Is 20 ° C. or lower. In the present invention, the glass transition temperature (Tg) is a value that can be measured by a differential thermal analyzer DSC, and the minimum film-forming temperature (MFT) is obtained by thinly applying a resin emulsion on a glass plate under a certain temperature condition. The temperature at the boundary between where the white powdery precipitate was formed and where the transparent thin film was formed was measured. Generally, the higher the glass transition temperature (Tg), the higher the minimum film-forming temperature (MFT) tends to be higher. The glass transition temperature (Tg) is almost determined by the type and molecular weight of the resin, whereas the minimum The film temperature (MFT) varies greatly depending on the particle diameter of the resin particles, the surface state of the particles, the affinity with the solvent, etc., in addition to the type and molecular weight of the resin, and the values do not necessarily match.
The resin component of the dispersed phase is not particularly limited as long as it satisfies the above-mentioned conditions, but preferred examples include acrylic resins, vinyl acetate resins, styrene-butadiene resins, vinyl chloride resins, acrylic resins. Hydrophobic resins such as styrene resin, butadiene resin, and styrene resin are listed.
These resin emulsions can be obtained by mixing resin particles with water in some cases together with a surfactant, but it is more industrially preferable to directly synthesize a resin monomer by a conventionally known emulsion polymerization method. Is also advantageous. As the emulsion polymerization method, for example, in the presence of an emulsifier, a polymerization initiator, a chain transfer agent, a chelating agent, a pH adjuster, etc. A polymerization reaction may be performed at a temperature for about 1 to 30 hours. For example, an emulsion of an acrylic resin or a styrene-acrylic resin is obtained by polymerizing a polymerizable monomer such as (meth) acrylic acid ester or (meth) acrylic acid ester and styrene in water together with a polymerization initiator. Obtainable.
The charge of the resin emulsion is imparted by any one or a combination of a functional group contained in the monomer, an initiator segment of a polymerization initiator, and an ionic surfactant. Examples of the monomer containing an ionic functional group include sodium styrene sulfonate, sodium allyl alkyl sulfonate, alkyl allyl sulfosuccinate, polyoxyethylene alkyl allyl glycerin ether sulfate, polyoxyethylene alkylphenol allyl glycerin ether sulfate, and dimethylaminoethyl. (Meth) acrylate, diethylaminoethyl (meth) acrylate, etc. are mentioned.
An emulsifier may be used as necessary, for example, higher alcohol sulfate sodium salt, alkylbenzene sulfonic acid sodium salt, succinic acid dialkyl ester sulfonic acid sodium salt, alkyl diphenyl ether disulfonic acid sodium salt, anionic surfactant, lauryltrimethylammonium And cationic surfactants such as chloride. These surfactants are usually used in an amount of 0 to 10 parts by weight with respect to 100 parts by weight of the polymerizable monobodies. In the present invention, it is preferable to use as little as possible in terms of preventing foaming and the like. .
Examples of the polymerization initiator include water-soluble persulfates, hydrogen peroxide, azo compounds, peroxides and the like generally used in emulsion polymerization. These polymerization initiators can be used by dissolving in water, a polymerizable compound or a solvent. In the present invention, a water-soluble persulfate such as potassium persulfate is preferably used as the polymerization initiator. These polymerization initiators add a sulfate group to the resin to be produced, and impart charge to the resin emulsion. The polymerization initiator as described above is usually used in an amount of 0.1 to 3 parts by weight with respect to 100 parts by weight of the polymerizable monomer. In emulsion polymerization, a reducing agent can be used in combination with a polymerization initiator.
Examples of such a reducing agent include sodium pyrobisulfite, sodium bisulfite, sodium thiosulfate, L-ascorbic acid and its salt, sodium formaldehyde sulfoxylate, and the like. Examples of the chain transfer agent include the following compounds: halogenated hydrocarbons such as chloroform and bromoform, mercaptans such as n-dodecyl mercaptan, t-dodecyl mercaptan, and n-octyl mercaptan, dimethylxanthogen disulfide, diisopropyl Xanthogens such as xanthogen disulfide, terpenes such as dipentene and terpinolene, unsaturated cyclic hydrocarbon compounds such as 9,10-dihydroanthracene, 1,4-dihydronaphthalene, indene and 1,4-cyclohexadiene, xanthene, 2 An unsaturated heterocyclic compound such as 5-dihydrofuran is used. The chain transfer agent is usually used in an amount of 0 to 5 parts by weight with respect to 100 parts by weight of the monomer.
Examples of chelating agents include glycine, alanine, ethylenediaminetetraacetic acid and the like.
Examples of the pH adjuster include sodium carbonate, potassium carbonate, sodium hydrogen carbonate, ammonia and the like.
The emulsion polymerization performed in the aqueous medium as described above may be performed in the presence of a small amount of an organic solvent as necessary, for example, methyl ethyl ketone, acetone, trichlorotrifluoroethane, methyl isobutyl ketone, dimethyl sulfoxide. Organic solvents such as toluene, dibutyl phthalate, methyl pyrrolidone, ethyl acetate, alcohols, cellosolves and carbinols can be used. This organic solvent is used within a range that does not impair workability, disaster prevention safety, environmental safety and production safety. Specifically, it is usually 5 parts by weight or less with respect to 100 parts by weight of the polymerizable monomer. Can be used. Emulsion polymerization performed in the presence of each component as described above can be performed by a known method such as a batch method, a semi-continuous method, or a continuous method.
The amount of the resin emulsion added to the recording liquid of the present invention is determined in relation to the amount of pigment to be added. In the present invention, it is necessary to dry in a form in which pigment particles and resin emulsion particles are mixed to form a film having clear color development, water resistance, and scratch resistance. As a result of intensive studies on this point, it has been found that the object can be achieved by adding the solid content in the range of 0.2 to 5 with respect to the weight of the pigment of 1.

<Other resins>
In the present invention, the resin can be used in combination as long as the storage stability and ejection stability of the treatment liquid are not impaired, and can be freely selected from, for example, a water-soluble polymer, an emulsion, and a latex.

<Surfactant>
As described above, the ink composition according to the present invention may contain a surfactant as necessary. As the surfactant, nonionic surfactants, amphoteric surfactants and / or anionic surfactants can be preferably used. In particular, fluorine-based surface activity, weak anion-based materials such as fluorine-based surface activity as represented by the following general formulas (I), (II) and (III) (R in the formulas (I) to (III)) Represents an alkyl group, Rf represents a perfluoroalkyl group, and n, m, p, and q are positive numbers)) and an alkyl ether carboxylate surfactant. Examples of the alkyl ether carboxylate surfactant include ECT-3NEX, ECTD-3NEX, ECTD-6NEX, ECT-3, ECT-7, AKYPO RLM 45NV (CHEM-Y), AKYPO RLM45 (manufactured by Nikko Chemicals Co., Ltd.) CHEM-Y), AKYPO RLM100NV (CHEM-Y), AKYPO RLM100 (CHEM-Y), or the like can be used. Particularly when ECTD-3NEX or ECTD-6NEX is used, good recording quality is exhibited. The amount of the alkyl ether carboxylate surfactant added is preferably about 0.1 to 5% by weight of the ink composition, more preferably about 0.5 to 1.5% by weight.

According to a preferred embodiment of the present invention, the ink composition according to the present invention can comprise other surfactants in order to control its permeability. This surfactant is preferably one having good compatibility with the ink composition, and among the surfactants, one having high permeability and stability is preferable.
Preferred examples thereof include amphoteric surfactants and nonionic surfactants.
Amphoteric surfactants include lauryldimethylaminoacetic acid betaine, 2-alkyl-N-carboxymethyl-N-hydroxyethylimidazolinium betaine, coconut oil fatty acid amidopropyldimethylaminoacetic acid betaine, polyoctylpolyaminoethylglycine and other imidazoline derivatives. is there. Nonionic surfactants include polyoxyethylene nonyl phenyl ether, polyoxyethylene octyl phenyl ether, polyoxyethylene dodecyl phenyl ether, polyoxyethylene alkyl allyl ether, polyoxyethylene oleyl ether, polyoxyethylene lauryl ether, polyoxyethylene Ethers such as ethylene alkyl ether and polyoxyalkylene alkyl ether, polyoxyethylene oleic acid, polyoxyethylene oleate, polyoxyethylene distearate, sorbitan laurate, sorbitan monostearate, sorbitan monooleate, sorbitan sesquis Esters such as oleate, polyoxyethylene monooleate, polyoxyethylene stearate, etc. Alkyl esters, such as fluorine-containing surfactants such as perfluoroalkyl carboxylate are exemplified.

<Sugar>
According to a preferred embodiment of the present invention, the clogging of the nozzles of the ink jet recording head is effectively prevented by adding saccharides. The saccharide may be a monosaccharide or a polysaccharide, and specific examples thereof include glucose, mannose, fructose, ribose, xylose, arabinose, lactose, galactose, aldonic acid, glucitolose, maltose, cellobiose, sucrose, trehalose, In addition to maltotriose and the like, alginic acid and its salts, cyclodextrins, and celluloses can be mentioned. The addition amount is preferably about 1% to 10%, more preferably 3 to 7%.

<Antioxidants, oxygen absorbers, UV absorbers>
Examples include ribofuran, L-ascorbic acid and salts thereof, carotene, hindered phenols, biotin, choline, tocopherol and the like.
Examples of commercially available antioxidants and ultraviolet absorbers in the pretreatment liquid and ink of the present invention include Tinuvin 328, 900, 1130, 384, 292, 123, 144, 622, 770, and 292 manufactured by Ciba Geigy. Irgacor 252, 153, Irganox 1010, 1076, 1035, MD1024, and the like.

<Preservatives and fungicides>
Preservatives and fungicides can be added to suppress the growth of fungi and increase the storage stability and image quality stability. Preferable specific examples of the antiseptic and fungicide include sodium benzoate, sodium pentachlorophenol, sodium 2-pyridinethiol-1-oxide, sodium sorbate, sodium dehydroacetate, 1,2-dibenzisothiazoline-3 -On (Avicia's Proxel CRL, Proxel BDN, Proxel GXL, Proxel XL-2, Proxel TN) and the like. The addition amount is preferably 0.01 to 3.0% by mass, and more preferably 0.5 to 2% by mass.

<Viscosity modifier>
In addition, the pretreatment liquid and ink composition according to the present invention can comprise a viscosity modifier. Specific examples thereof include rosins, alginic acids, polyvinyl alcohol, hydroxypropyl cellulose, carboxymethyl cellulose, hydroxyethyl cellulose, methyl cellulose, polyacrylate, polyvinyl pyrrolidone, gum arabic starch and the like.

<Rust preventive>
In the present invention, a film is formed on the metal surface in contact with the head or the like so as to prevent corrosion, so that acid sulfite, sodium thiosulfate, ammonium thiodiglycolate, diisopropylammonium nitrite, Rust preventives such as pentaerythritol nitrate and dicyclohexylammonium nitrite can be added. 0.01-3.0 mass% is preferable and, as for the addition amount of a rust preventive agent, 0.5-2 mass% is more preferable.

<PH adjuster>
Further, in the present invention, in order to adjust pH without adversely affecting the ink to be prepared and the pretreatment liquid, hydroxides of alkali metal elements such as lithium hydroxide, sodium hydroxide, potassium hydroxide, Ammonium hydroxide, quaternary ammonium hydroxide, quaternary phosphonium hydroxide, alkali metal carbonates such as lithium carbonate, sodium carbonate, potassium carbonate, amines such as diethanolamine, triethanolamine, boric acid, hydrochloric acid, A pH adjuster such as nitric acid, sulfuric acid, and acetic acid can be used. The addition amount of the pH adjuster is preferably 0.01 to 3.0% by mass, and more preferably 0.5 to 2% by mass.

[Recording medium]
The recording medium in the present invention is not particularly limited and may be appropriately selected depending on the intended purpose. Examples thereof include plain paper, glossy paper, special paper, cloth, film, and OHP sheet. These may be used individually by 1 type and may use 2 or more types together.
Conventionally, in order to obtain high-quality images in inkjet recording, specially processed glossy paper has been recommended. However, such dedicated glossy paper has both the gloss and ink droplet absorption. For this reason, limited extender pigments are used and are relatively expensive. However, in the present invention, color bleed, feathering, and set-off are reduced on plain paper called “quality paper”, and a clear image can be obtained with high density. Can do.

[Inkjet recording method, recording apparatus]
The ink set of the present invention can be suitably used for various recording apparatuses based on the ink jet recording system, for example, an ink jet recording printer, a facsimile apparatus, a copying apparatus, a printer / fax / copier multifunction machine, and the like. In addition, it has an excellent characteristic that the head does not adhere to a recording apparatus including an ink jet head having an ink repellent layer containing a fluorine-based silane coupling agent or an ink repellent layer containing a silicone resin.
The outline of the ink jet recording apparatus used in the examples will be described below.
The ink jet recording apparatus shown in FIG. 1 has an apparatus main body (101), a paper feed tray (102) for loading paper mounted on the apparatus main body (101), and an image mounted on the apparatus main body (101). A paper discharge tray (103) for stocking the formed paper and an ink cartridge loading section (104) are provided. On the upper surface of the ink cartridge loading section (104), an operation section (105) such as operation keys and a display is arranged. The ink cartridge loading unit (104) has an openable / closable front cover (115) for attaching and detaching the ink cartridge (200). (111) is the upper cover, and (112) is the front surface of the front cover.

In the apparatus main body (101), as shown in FIGS. 2 and 3, a guide rod (131), which is a guide member horizontally mounted on left and right side plates (not shown), and a stay (132), a carriage (133) ) Is slidably held in the main scanning direction, and is moved and scanned in the direction indicated by the arrow in FIG. 3 by a main scanning motor (not shown).
The carriage (133) includes a plurality of recording heads (134) including four inkjet recording heads that discharge ink droplets of each color of yellow (Y), cyan (C), magenta (M), and black (Bk). Are arranged in a direction crossing the main scanning direction, and the ink droplet ejection direction is directed downward.
As an inkjet recording head constituting the recording head (134), a piezoelectric actuator such as a piezoelectric element, a thermal actuator that utilizes a phase change caused by liquid film boiling using an electrothermal transducer such as a heating resistor, and a temperature change A shape memory alloy actuator using a metal phase change, an electrostatic actuator using an electrostatic force, or the like provided as energy generating means for discharging ink can be used.
The carriage (133) is equipped with a sub tank (135) for each color for supplying ink of each color to the recording head (134). The sub tank (135) is supplied with ink according to the ink set of the present invention from the ink cartridge (200) of the present invention loaded in the ink cartridge loading section (104) via an ink supply tube (not shown). To be replenished.
On the other hand, as a paper feeding unit for feeding paper (142) (one typical example of a recording medium) loaded on a paper stacking unit (pressure plate) (141) of the paper feed tray (103), a paper stacking unit ( 141) a half-moon roller (sheet feeding roller (143)) for separating and feeding the sheets (142) one by one from the sheet 141) and a separation pad (144) made of a material having a large friction coefficient facing the sheet feeding roller (143). The separation pad (144) is urged toward the paper feed roller (143).
A conveying belt (151) for electrostatically adsorbing and conveying the paper (142) as a conveying unit for conveying the paper (142) fed from the paper feeding unit below the recording head (134). A counter roller (152) for conveying the paper (142) sent from the paper supply unit via the guide (145) between the conveying belt (151) and a paper (substantially vertically upward) ( 142) and a leading guide roller 153 urged toward the conveying belt (151) by the holding member (154). (155) and a charging roller (156) which is a charging means for charging the surface of the conveyor belt (151).
The conveyance belt (151) is an endless belt, is stretched between the conveyance roller (157) and the tension roller (158), and can circulate in the belt conveyance direction. The transport belt (151) includes, for example, a surface layer serving as a sheet adsorbing surface formed of a resin material having a thickness of about 40 μm without resistance control, for example, a copolymer of tetrafluoroethylene and ethylene (ETFE), It has the same material as the surface layer and a back layer (medium resistance layer, earth layer) that has been subjected to resistance control by carbon. On the back side of the conveyance belt (151), a guide member (161) is arranged corresponding to the printing area by the recording head (134). As a paper discharge unit for discharging the paper (142) recorded by the recording head (134), a separation claw (171) for separating the paper (142) from the transport belt (151), and paper discharge A roller (172) and a paper discharge roller (173) are provided, and a paper discharge tray (103) is arranged below the paper discharge roller (172).
A double-sided paper feeding unit (181) is detachably attached to the back surface of the apparatus main body (101). The double-sided paper feeding unit (181) takes in the paper (142) returned by the reverse rotation of the transport belt (151), reverses it, and feeds the paper again between the counter roller (152) and the transport belt (151). To do. A manual paper feed unit (182) is provided on the upper surface of the double-sided paper feed unit (181).
In this ink jet recording apparatus, the sheet (142) is separated and fed one by one from the sheet feeding unit, and the sheet (142) fed substantially vertically upward is guided by the guide (145) and the transport belt (151). ) And the counter roller (152). Further, the leading end is guided by the conveying guide (153) and pressed against the conveying belt (151) by the leading end pressure roller (155), and the conveying direction is changed by about 90 °.
At this time, the conveyance belt (157) is charged by the charging roller (156), and the paper (142) is electrostatically adsorbed to the conveyance belt (151) and conveyed. Therefore, by driving the recording head (134) according to the image signal while moving the carriage (133), ink droplets are ejected onto the stopped sheet (142) to record one line, and the sheet ( 142), the next line is recorded after a predetermined amount is conveyed. Upon receiving a recording end signal or a signal that the rear end of the paper (142) has reached the recording area, the recording operation is finished and the paper (142) is discharged to the paper discharge tray (103).
When the near-end of the pretreatment liquid or ink remaining in the sub tank (135) is detected, a required amount of the pretreatment liquid or ink is supplied from the ink cartridge (200) to the sub tank (135).
In this ink jet recording apparatus, when the pretreatment liquid or ink in the ink cartridge (200) of the present invention is used up, the casing of the ink cartridge (200) is disassembled and only the internal pretreatment liquid bag or ink bag is removed. Can be exchanged. Further, the ink cartridge (200) can supply ink stably even when the ink cartridge (200) is vertically placed and has a front loading configuration. Therefore, even when the upper part of the apparatus main body (101) is closed and installed, for example, even when it is stored in a rack or an object is placed on the upper surface of the apparatus main body (101), the ink The cartridge (200) can be easily replaced.
Here, an example is described in which the present invention is applied to a serial (shuttle type) ink jet recording apparatus that is scanned by a carriage, but the present invention can be similarly applied to a line type ink jet recording apparatus having a line type head.
As described above, the substantially colorless pretreatment liquid containing no colorant is applied to the recording medium (hereinafter referred to as pretreatment), and the substantially colorless pretreatment liquid containing no colorant is dried and solidified. In addition, in order to record an image with an ink containing a colorant, one of the ink cartridge and the ink bag can be a pretreatment liquid cartridge or a pretreatment liquid bag.

[Inkjet recording method]
The ink jet recording method of the present invention can be realized by using the above ink jet recording apparatus. However, in order to perform it more effectively, it is the same as or wider than the image formed with the ink containing the colorant. It is necessary to apply a substantially colorless pretreatment liquid containing no colorant to the recording medium in advance. As a result, agglomeration of acetoacetyl-modified polyvinyl alcohol or carboxyl-modified polyvinyl alcohol as a water-soluble resin in the ink with a polyvalent metal salt or a cationic substance in the pretreatment liquid is preferably generated, and color bleeding in an ink jet print image is achieved. , Feathering, and setback can be reduced.

  Hereinafter, the present invention will be described in more detail and specifically by way of examples. However, these examples are intended to facilitate understanding of the present invention and are not intended to limit the present invention. Further, in the following description, “part” represents “part by mass” unless otherwise specified.

[Synthesis Example 1]
After sufficiently replacing the inside of the 1 L flask equipped with a mechanical stirrer, thermometer, nitrogen gas introduction tube, reflux tube and dropping funnel with nitrogen gas, 11.2 g of styrene, 2.8 g of acrylic acid, 12.0 g of lauryl methacrylate, 4.0 g of polyethylene glycol methacrylate, 4.0 g of styrene macromer (manufactured by Toa Gosei Co., Ltd., trade name: AS-6) and 0.4 g of mercaptoethanol were charged and heated to 65 ° C. Next, 100.8 g of styrene, 25.2 g of acrylic acid, 108.0 g of lauryl methacrylate, 36.0 g of polyethylene glycol methacrylate, 60.0 g of hydroxyethyl methacrylate, styrene macromer (manufactured by Toa Gosei Co., Ltd., trade name: AS-6) 36 A mixed solution of 0.0 g, mercaptoethanol 3.6 g, azobisdimethylvaleronitrile 2.4 g and methyl ethyl ketone 18 g was dropped into the flask over 2.5 hours. After completion of dropping, a mixed solution of 0.8 g of azobisdimethylvaleronitrile and 18 g of methyl ethyl ketone was dropped into the flask over 0.5 hours. After aging at 65 ° C. for 1 hour, 0.8 g of azobisdimethylvaleronitrile was added, and further aging was performed for 1 hour. After completion of the reaction, 364 g of methyl ethyl ketone was added to the flask to obtain 800 g of a polymer solution having a concentration of 50%.

[Preparation Example 1]
After thoroughly stirring 28 g of the polymer solution prepared in Synthesis Example 1, 26 g of carbon black (manufactured by MONARCH880 / Cabot), 13.6 g of 1 mol / L potassium hydroxide solution, 20 g of methyl ethyl ketone, and 30 g of ion-exchanged water, a three-roll mill Were kneaded using. The obtained paste was put into 200 g of ion-exchanged water and sufficiently stirred, and then methyl ethyl ketone and water were distilled off using an evaporator to obtain an aqueous dispersion of water-insoluble vinyl polymer particles having a solid content of 20% by mass. .

[Production Example 1]
-Production of support-
A 0.3 mass% slurry having the following composition was made with a long paper machine to prepare a support having a basis weight of 79 g / m ² . In addition, in the size press process of the papermaking process, the oxidized starch aqueous solution was applied so that the solid content was 1.0 g / m ² per side.
-Hardwood bleached kraft pulp (LBKP) 80 parts by mass-Softwood bleached kraft pulp (NBKP) 20 parts by weight-Light calcium carbonate (trade name: TP-121, manufactured by Okutama Kogyo Co., Ltd.) 10 parts by weight-Aluminum sulfate 1.0 mass Part / amphoteric starch (trade name: Cato3210, manufactured by NSC Japan) 1.0 part by weight / neutral rosin sizing agent (trade name: NeuSize M-10, manufactured by Harima Kasei Co., Ltd.)
0.3 part by mass / yield improver (trade name: NR-11LS, manufactured by Hymo) 0.02 part by mass

[Pretreatment liquid]
68 parts of water, 2 parts of 2-methyl-1,3-hexanediol, 5 parts of glycerin, 10 parts of diethylene glycol, 10 parts of lactic acid as an acid, magnesium nitrate tetrahydrate as a polyvalent metal salt 5 parts of the product was mixed to prepare 100 parts of the pretreatment liquid 1.

[Black ink]
21 parts of water, 16 parts of 3-methyl-1,3-hexanediol as a water-soluble organic solvent, 8 parts of glycerin, 50 parts of acetoacetyl-modified polyvinyl alcohol (Z200 manufactured by Nippon Synthetic Chemical Industry Co., Ltd.), resin-coated type as a colorant 50 parts of a pigment (carbon black: MONARCK 880 base water-insoluble styrene acrylic polymer particle aqueous dispersion manufactured by Cabot) and 1 part of a fluorosurfactant of the above general formula (II) as a surfactant are mixed, and 100 parts of Black ink 1 was prepared.

[Inkjet printing]
The ink jet printer shown in FIG. 1 was filled with the adjusted ink, and the plain paper prepared in Production Example 1 was printed with a solid black of composite black using four colors of CYMK at a resolution of 1200 dpi.

[Test conditions and evaluation criteria]
The obtained images were tested for image density, smear fixing properties, spur marks, marker resistance, feathering, and color bleed according to the following test modes and evaluation criteria. The results are shown in Table 4-1.
[Image density]
The ink jet printer shown in FIG. 1 was filled with the adjusted ink, and the plain paper prepared in Production Example 1 was printed with a solid black of composite black using four colors of CYMK at a resolution of 1200 dpi. After printing and drying, the image density was measured using a reflective color spectrocolorimeter (manufactured by X-Rite).
The adhesion amount at this time was 9.5 g / m ² .
[Smear fixing]
After 3 hours or more have elapsed after printing, the solid image portion printed on the white cotton cloth (manufactured by Toyo Seiki Co., Ltd.) attached to the clock meter (manufactured by Toyo Seiki Co., Ltd.) is reciprocated 10 times to visually check the ink stains on the white cotton cloth Observed and evaluated according to the following criteria.
Rank 5: No dirt Rank 4: Slightly dirt Rank 3: Dirt is present but no problem in practical use Rank 2: Dirt is slightly noticeable Rank 1: Dirt is noticeable [spur mark]
The degree of spurs on each image print was visually observed and evaluated according to the following criteria.
〔Evaluation criteria〕
A: Not recognized at all.
○: Slightly recognized.
X: Spur marks are clearly recognized.
[Marker resistance]
The recording medium is changed to Type 6200 paper (manufactured by NBS Ricoh), and the resolution is 600 dpi.
Except for the changed points, solid printing was performed in the same manner as in the case of the above-described measurement of image density and the like.
After the printing was dried, the printed part was traced with a fluorescent marker (Made by Mitsubishi Pencil Co., Ltd., PROPUS2), and the degree of stain generated by removing the pigment was visually observed and evaluated according to the following criteria.
〔Evaluation criteria〕
Rank 5: No stain due to discoloration is observed.
Rank 4: Dirt due to discoloration is hardly seen.
Rank 3: Some dirt is seen.
Rank 2: Dirt is seen.
Rank 1: Dirt spreads along the marker.
[Feathering]
The black image portion was observed, and the image quality was evaluated by comparing with the rank sample.
Rank 5: No exudation Rank 4: Slight exudation Rank 3: Exudation, but no problem in practical use Rank 2: Excessive exudation Rank 1: Excessive exudation [Color bleed]
The image quality was evaluated by observing the boundary between black solid and yellow solid and comparing it with a rank sample.
Rank 5: No color mixture Rank 4: Slightly mixed color Rank 3: Mixed color, but no problem in practical use Rank 2: Slightly mixed color Rank 1: Many mixed colors

  As outlined in Table 4-1, instead of magnesium nitrate tetrahydrate as the polyvalent metal salt in the pretreatment liquid 1 of Example 1, polyallylamine acetate (Nittobo Co., Ltd.) was used as the cationic substance. An ink jet print image was obtained and evaluated in the same manner as in Example 1 except that the pretreatment liquid 2 prepared using PAA-D19A) was used. The results are shown in Table 4-1.

  As shown in Table 4-1, the ink liquid 2 prepared by using carboxyl-modified polyvinyl alcohol (T330H, manufactured by Nippon Synthetic Chemical Industry) instead of acetoacetyl-modified polyvinyl alcohol (Z200) in the ink of Example 1 was used. An ink jet print image was obtained and evaluated in the same manner as in Example 1 except that it was used. The results are shown in Table 4-1.

  As shown in Table 4-1, except that the ink liquid 3 in Example 1 was replaced with a self-dispersing pigment (carbon black; Toka Black # 7240 manufactured by Tokai Carbon Co., Ltd.). Inkjet print images were obtained and evaluated in the same manner as in Example 1. The results are shown in Table 4-1.

[Comparative Example 1]
As shown in Table 4-2, an inkjet print image was obtained and evaluated in the same manner as in Example 1 except that the pretreatment using the pretreatment liquid in Example 1 was not performed. The results are shown in Table 4-2.

[Comparative Example 2]
As shown in Table 4-2, an inkjet print image was obtained and evaluated in the same manner as in Example 1 except that the pretreatment liquid 3 containing no polyvalent metal salt or cationic substance was used. The results are shown in Table 4-2.

[Comparative Example 3]
As shown in Table 4-2, inkjet print images were obtained and evaluated in the same manner as in Example 1 except that the ink liquid 4 containing neither acetoacetyl-modified polyvinyl alcohol nor carboxyl-modified polyvinyl alcohol was used. The results are shown in Table 4-2.

[Comparative Example 4]
As shown in Table 4-2, except that the pretreatment liquid 3 containing no polyvalent metal salt or cationic substance and the ink liquid 4 containing no acetoacetyl-modified polyvinyl alcohol or carboxyl-modified polyvinyl alcohol were used. In the same manner as in Example 1, an inkjet print image was obtained and evaluated. The results are shown in Table 4-2.

DESCRIPTION OF SYMBOLS 101 Main body 102 Paper feed tray 103 Paper discharge tray 104 Ink cartridge loading part 105 Operation part 111 Upper cover 112 Front cover front 115 Front cover 131 Guide rod 132 Stay 133 Carriage 134 Recording head 135 Sub tank 141 Paper placement part 142 Paper 143 Feed roller 144 Separator pad 145 Guide 151 Transport belt 152 Counter roller 153 Transport guide 154 Pressing member 155 Pressure roller 156 Charging roller 157 Transport roller 158 Tension roller 161 Guide member 171 Separating claw 172 Paper discharge roller 173 Paper discharge roller 181 Double-sided feeding Paper unit 182 Manual paper feed unit 200 Cartridge 241 Storage bag 242 Inlet 243 Outlet 244 Cartridge case

JP-A-5-202328 JP-A-6-106735 JP-A-3-240557 JP-A-3-240558 JP 2007-162003 A Japanese Patent Laid-Open No. 2002-211106

Claims (12)

  In an ink jet recording method for discharging and recording an ink jet recording ink onto a recording medium to which a pretreatment liquid has been applied in advance, the pretreatment liquid is preliminarily applied to the recording medium. It is carried out by a step of selectively ejecting a pretreatment liquid to the contact area with the recording ink, and the pretreatment liquid contains a polyvalent metal salt or a cationic substance in the pretreatment liquid medium. The ink contains at least a pigment as a colorant and a water-soluble resin in an ink liquid medium composed of water and a water-soluble organic solvent, and the water-soluble resin is acetoacetyl-modified polyvinyl alcohol or carboxyl An ink jet recording method comprising a modified polyvinyl alcohol.   2. The ink jet recording method according to claim 1, wherein the pigment of the recording ink is composed of an aqueous dispersion of water-insoluble vinyl polymer particles.   The pretreatment liquid is an ink jet pretreatment liquid, and the polyvalent metal salt or the cationic substance is dissolved in a pretreatment liquid medium. Inkjet recording method.   4. The ink jet recording method according to claim 3, wherein the liquid medium for the pretreatment liquid is water or a mixture of water and a water-soluble organic solvent.   5. The ink jet recording method according to claim 4, wherein the pretreatment liquid medium has a higher water content ratio than the ink liquid medium.   6. The ink jet recording method according to claim 1, wherein the recording medium is plain paper.   An ink set for ink jet recording comprising a combination of a pretreatment liquid previously applied to a recording medium and an ink jet recording ink subsequently ejected onto the recording medium, wherein the pretreatment liquid comprises a polyvalent metal A salt or a cationic substance is contained in the pretreatment liquid medium, and is selectively applied to the contact area with the recording ink by inkjet jetting, and the ink is at least water and a water-soluble organic solvent. The ink liquid medium comprising a pigment as a colorant and a water-soluble resin, wherein the water-soluble resin contains acetoacetyl-modified polyvinyl alcohol or carboxyl-modified polyvinyl alcohol. Ink set for inkjet recording.   8. The ink set for ink jet recording according to claim 7, wherein the pigment of the recording ink is constituted by an aqueous dispersion of water-insoluble vinyl polymer particles.   The ink set for ink jet recording according to claim 7 or 8, wherein the above is dissolved in a liquid medium for pretreatment liquid.   The ink set for inkjet recording according to claim 9, wherein the liquid medium for the pretreatment liquid is water or a mixture of water and a water-soluble organic solvent.   The ink set for ink jet recording according to claim 10, wherein the liquid medium for pretreatment liquid has a higher content ratio of water than the liquid medium for ink.   The ink set for ink-jet recording according to claim 7, wherein the recording medium is plain paper.

Images