JP2009137053A - Inkjet recording reactive liquid, inkjet recording method and inkjet recording ink set - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an inkjet recording reactive liquid which can solve a bleeding phenomenon as a priority subject in printing a sheet of paper by the inkjet recording process and form an image showing a compatibility between grab and color developing properties without causing a strike-through, when this reactive liquid is used with a colored pigmented ink, and further, can achieve the continuous discharge of ink and the stable formation of an image for a far longer time, compared with the case when this reactive liquid is not used, and to provide an inkjet recording method and an inkjet recording ink set. <P>SOLUTION: This inkjet recording reactive liquid is used with the colored pigmented ink and generates a chemical reaction when the former comes into contact with the latter. In addition, the reactive liquid contains (a) a polyvalent metallic salt, (b) a malonate and (c) a liquid medium. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an ink jet recording reaction solution, an ink jet recording method, and an ink jet recording ink set that enable formation of a high-quality color image on an ink jet recording medium (particularly plain paper).

  In the ink jet recording method, recording is performed by ejecting fine droplets of a recording liquid (colored ink) from an ink jet recording head, causing the liquid droplets to fly and adhering to a recording medium such as paper. There are various means for supplying ejection energy for flight, such as a system that uses an electrothermal converter and ejects liquid droplets by applying thermal energy to ink to generate bubbles. Above all, the above-described method using thermal energy can easily realize a high-density multi-orifice of the recording head and can record high-resolution and high-quality images at high speed (Patent Documents 1 to 3).

  However, since the color ink used in inkjet recording has been mainly composed of water, there is a problem that it is difficult to obtain a good image when plain paper is used as a recording medium. there were. Conventionally used inks generally contain water as a main component and contain a water-soluble high-boiling solvent such as glycol for the purpose of drying and clogging. In particular, when a color image is to be obtained, the above-mentioned problems may occur remarkably because different colored inks are successively stacked before the previously applied colored ink is completely fixed. That is, in this case, the colors are blurred at the boundary portion of the color and mixed in a non-uniform manner (hereinafter referred to as “bleeding”), and a satisfactory image cannot be obtained.

  Patent Document 4 discloses that as a means for improving bleeding, a compound such as a surfactant that improves the permeability to a recording medium is added to a colored ink. In this method, bleeding is suppressed to some extent by increasing the penetration speed of the colored ink into the recording medium, but there are the following problems. That is, the colorant in the ink penetrates deep into the recording medium due to the effect of the surfactant, and the density and clearness of the image are lowered, and the ink reaches the back surface of the recording medium, and the image is seen through from the back surface. There were inconveniences such as being visible (hereinafter referred to as “behind”). In addition, the wettability with respect to the surface of the recording medium is increased at the same time, so that the colored ink easily spreads on the recording medium, resulting in a problem that the resolution is lowered and the image looks blurred.

  As another means, various methods for applying another liquid (reaction liquid) for improving the image on the recording medium prior to the discharge of the colored ink have been proposed. For example, Patent Document 5 discloses a method in which a solution of a polymer such as carboxymethyl cellulose, polyvinyl alcohol, or polyvinyl acetate is previously applied to a recording medium, and then recording is performed with a colored ink. However, although this method can improve the problem of occurrence of bleeding, it takes time to dry the image, and there is a problem in fixability.

  In order to improve this, Patent Document 6 discloses a method of recording with a colored ink containing an anionic dye after applying a liquid containing an organic compound having two or more cationic groups per molecule. It is disclosed. Patent Document 7 discloses a method of recording with colored ink after applying an acidic liquid.

  However, in any case, although the problem of bleeding is improved, the reactivity of the reaction solution is not so high, so most of the reaction occurs inside the recording medium, resulting in a problem that the color developability does not improve, There was still a problem with the above-mentioned strikethrough.

  On the other hand, as a method using a more effective material, Patent Document 8 discloses a method of suppressing bleeding using a reaction between a polyvalent metal ion and a carboxyl group. Furthermore, Patent Document 9 discloses a method for improving bleeding by reaction with a pigment, a resin emulsion, and a polyvalent metal salt. Although the reaction liquid for ink jet recording containing these polyvalent metal ions is excellent in the effect as the reaction liquid, there are the following problems when the ink jet recording system applied to the recording medium is based on the action of thermal energy. It was. That is, in such a reaction liquid containing polyvalent metal ions, there is a problem that the discharge speed greatly varies depending on the driving frequency, and that the discharge itself stops when the reaction liquid is continuously discharged for a long time. there were.

  Regarding the problem that the discharge speed of the reaction liquid varies depending on the driving frequency, Patent Document 10 discloses that the reaction liquid can be improved by adding a certain salt typified by ammonium nitrate to the reaction liquid. However, in this case, although the dependency of the ejection speed on the driving frequency is improved, there is a problem that, on the contrary, the tendency that ejection is stopped by continuous ejection becomes more conspicuous. Patent Document 11 discloses that continuous discharge characteristics can be improved by adding an acid having an amino group to a reaction liquid containing polyvalent metal ions. Not touched.

Japanese Patent Publication No. 61-59911 Japanese Patent Publication No. 61-59912 Japanese Examined Patent Publication No. 61-59914 JP 55-65269 A JP-A-56-89595 JP 63-29971 A Japanese Unexamined Patent Publication No. 64-9279 JP-A-5-202328 JP-A-9-207424 JP 2000-136337 A JP 2002-172847 A

  As described above, there are various effective proposals using colored ink and reaction liquid as one of the means for improving bleeding and show-through, but in any case, some improvement is not seen. However, it does not satisfy all the problems.

  Accordingly, an object of the present invention is to provide a reaction liquid for ink jet recording capable of realizing the following image formation, a recording method using the same, and an ink set comprising a combination of the reaction liquid and a colored pigment ink. There is. In other words, the problem of bleeding, which is a major problem when printing on plain paper by the inkjet recording method, is improved, and it is possible to form a good image that achieves both fixing and coloring without causing back-through. There is. In addition, another object of the present invention is to provide an ink jet recording reaction solution that can be continuously ejected for a much longer period of time than before, thereby enabling the above-described excellent image formation to be performed stably.

  The above object is achieved by the present invention described below. That is, the present invention is a reaction liquid for inkjet recording that is used together with a color pigment ink and that reacts when contacted with the color pigment ink, and includes (a) a polyvalent metal salt, (b) malonic acids, and (c And a liquid medium. In particular, the malonic acid (b) is preferably a compound selected from malonic acid, methylmalonic acid, dimethylmalonic acid, ethylmalonic acid, diethylmalonic acid, butylmalonic acid, and salts thereof.

  Another embodiment of the present invention is an ink jet recording method using the above-described ink jet recording reaction liquid, wherein the ink jet reaction liquid is supplied with energy and discharged toward a recording medium, and the reaction liquid is recorded. After or before application on the medium, energy is applied to the color pigment ink, and the ink is ejected toward the recording medium and applied onto the recording medium. The application is performed on the recording reaction liquid and the color pigment ink. Is an ink jet recording method that is performed in such a manner as to be arranged in contact with a recording medium.

  Another embodiment of the present invention is for inkjet recording, characterized in that at least the reaction liquid for inkjet recording described above is combined with a color pigment ink that reacts by contact with the reaction liquid for inkjet recording. It is an ink set.

  According to the present invention, by using the reaction liquid for inkjet recording of the present invention together with the color pigment ink, when image formation is performed on plain paper, formation of a high-quality color image with no bleeding and good color developability. Can be performed. At the same time, even when the image forming method applies the reaction liquid to the recording medium by the action of thermal energy, the ink recording reaction liquid of the present invention does not impair the discharge characteristics, and as a result, a clear and stable image can be obtained. It can be obtained continuously over a long period of time.

  Hereinafter, the present invention will be described in more detail with reference to preferred embodiments. The reaction liquid for inkjet recording of the present invention is used together with at least a colored pigment ink, and reacts when contacted with the colored pigment ink, and comprises (a) a polyvalent metal salt, (b) malonic acids, (C) A liquid medium is included. Hereinafter, each of these constituent materials will be described.

[Reaction solution for inkjet recording]
(A) Multivalent metal salt The reaction liquid for inkjet recording of the present invention contains a polyvalent metal salt as a reactant. The polyvalent metal salt means a divalent or higher valent metal ion and an anion that binds to these polyvalent metal ions. Although it does not specifically limit as polyvalent metal ion which comprises polyvalent metal salt, As a specific example, divalent metal ions, such as magnesium, calcium, barium, iron (II), copper (II), zinc, iron (III And trivalent metal ions such as aluminum. Moreover, although it does not specifically limit as an anion, As a specific example, a bromide ion, a chloride ion, a nitrate ion, an acetate ion, a lactate ion, a sulfate ion etc. are mentioned, for example.

  Specific examples of the polyvalent metal salt composed of the above-described divalent or higher polyvalent metal ions and anions are not particularly limited, but those listed below can be used. . For example, chlorides such as magnesium chloride, calcium chloride, barium chloride, iron (II) chloride, copper (II) chloride, zinc chloride, aluminum chloride, iron (III) chloride. Bromides such as magnesium bromide, calcium bromide, barium bromide, iron (II) bromide, copper (II) bromide, zinc bromide. Nitrates such as magnesium nitrate, calcium nitrate, barium nitrate, iron (II) nitrate, copper (II) nitrate, zinc nitrate, aluminum nitrate. Acetates such as magnesium acetate, calcium acetate, barium acetate, iron (II) acetate, copper (II) acetate, and zinc acetate. Lactates such as magnesium lactate and calcium lactate. Examples include magnesium glycerophosphate, calcium glycerophosphate, and alum. These may contain crystal water in a normal form.

  The addition amount of the polyvalent metal salt is not particularly limited, but may be a concentration sufficient to react with the color pigment ink and form an aggregate instantly. For example, the concentration in terms of polyvalent metal ion is 0.13 mol / kg or more and 1.2 mol / kg or less (reaction solution), more preferably 0.2 mol / kg or more and 0.8 mol / kg or less (reaction solution). ), Is a preferred range. If the concentration in terms of polyvalent metal ions in the reaction solution is lower than this, the effect as a reaction solution will be extremely reduced, and even if it is too high, no improvement in the effect will be seen, such as the generation of precipitates and increase in viscosity, etc. Since another problem may occur, it is not preferable.

(C) Liquid medium The reaction liquid for inkjet recording of the present invention comprises a polyvalent metal salt as mentioned above in a liquid medium. Examples of the liquid medium include water, water-soluble organic solvents, and other various additives. Although it does not specifically limit as a water-soluble organic solvent, As a specific example, the following can be used. Alkyl alcohols having 1 to 4 carbon atoms such as methyl alcohol, ethyl alcohol, n-propyl alcohol, isopropyl alcohol, n-butyl alcohol, sec-butyl alcohol, tert-butyl alcohol; Amides such as N, N-dimethylformamide and N, N-dimethylacetamide, ketones such as acetone and diacetone alcohol, and ketoalcohols. Cyclic ethers such as tetrahydrofuran and dioxane. Ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 1,2-hexanediol, 1,6-hexane Glycols such as diol, diethylene glycol, triethylene glycol, and thiodiglycol. Lower alkyl ethers of polyhydric alcohols such as ethylene glycol monomethyl (or ethyl) ether, diethylene glycol monomethyl (or ethyl) ether, triethylene glycol monomethyl (or ethyl) ether. Polyalkylene glycols such as polyethylene glycol and polypropylene glycol. Triols such as glycerin, 1,2,6-hexanetriol, and trimethylolpropane. N-methyl-2-pyrrolidone, 2-pyrrolidone, 1,3-dimethyl-2-imidazolidinone and the like can be mentioned. These may be used alone or in combination of two or more.

  The content of the water-soluble organic solvent in the reaction liquid for ink jet recording of the present invention is not particularly limited, but is 3% by mass to 60% by mass, more preferably 5% by mass with respect to the total mass of the reaction liquid. The preferred range is 30% by mass or less.

  As various additives used as the liquid medium, for example, a surfactant, an antifoaming agent, an antiseptic, a so-called “curling inhibitor” that suppresses warping of the recording medium after recording, and the like are used as appropriate. Can do.

(B) Malonic acids The above is the basic composition of the reaction liquid for ink jet recording of the present invention. The reaction liquid of the present invention is characterized by further containing malonic acids as a constituent component in addition to these. . Although it does not specifically limit as malonic acids used by this invention, The following are mentioned as a specific example. Examples thereof include compounds selected from lower alkyl group-substituted malonic acids such as malonic acid, methylmalonic acid, dimethylmalonic acid, ethylmalonic acid, diethylmalonic acid, and butylmalonic acid, halogen-substituted malonic acids, and salts thereof. The content of malonic acids constituting the reaction liquid for ink jet recording of the present invention is not particularly limited, but is preferably added within the following range. The range of 0.0005 mol / kg or more and 0.15 mol / kg or less (reaction solution) is preferable, and it is desirable that 1/300 or more is contained in a molar ratio with respect to polyvalent metal ions in the reaction solution. In addition, when the addition amount is less than this, the following predetermined effects cannot be expected, which is not preferable.

  According to the study by the present inventors, the following effects can be expected in particular by adding malonic acids to the reaction solution. When the reaction liquid is discharged by the action of thermal energy, the dependency of the discharge speed on the frequency, that is, the phenomenon that the discharge speed of the droplets decreases or stops as the drive frequency increases, and for a long time. Both the deterioration phenomenon of continuous discharge durability performance is improved.

  The details of the mechanism by which such effects can be obtained by adding malonic acids as described above to the reaction solution are unknown. However, the phenomenon of “if nothing is added, precipitates are generated on the surface of the heater that imparts thermal energy to the reaction solution, and then the surface of the heater is rough and breaks” is significantly suppressed by the addition of malonic acids. Therefore, the following assumptions are made. In other words, the polyvalent metal salt locally forms an extremely strong alkaline environment due to the thermochemical reaction on the heater surface, and a part thereof becomes an oxide and precipitates. Although the heater surface is protected by a corrosion-resistant material, the heater surface is damaged if the strong alkaline environment continues for a long time, and it is necessary to neutralize it by some method. However, generally known acids are not effective in neutralizing local portions because they immediately release protons in a neutral to weakly alkaline environment.

  In contrast, malonic acids are characterized by having a second-stage acid group that is a weak acid with a relatively large pKa value at 25 ° C., and release protons for neutralization only when the alkali is extremely strong. To do. For this reason, it can be presumed that the above-mentioned effect was obtained by selectively neutralizing only a strong alkaline environment in the vicinity of the heater surface. In addition, malonic acids also have an acid group that is a strong acid having a relatively low pKa value at 25 ° C. in the molecule, so that the solubility in the reaction solution is increased, the diffusibility as a molecule is improved, and the locality is increased. This is thought to have further contributed to neutralization of such parts. In addition, pKa said here represents the logarithm value of the reciprocal number of acid dissociation constant Ka, and means a strong acid, so that a numerical value is small, and a weak acid, so that a numerical value is large.

  In addition, among the malonic acid compounds exemplified above, it has been used so far because it is effective in preventing ink kogation in a method in which droplets are ejected by generating bubbles by applying thermal energy to the ink. It was sometimes done. However, the mechanism is fundamentally different from that of the present invention. For example, citric acid, which is known as an effective anti-koggi agent, has been used only for the purpose of preventing kogation, such as exhibiting a completely opposite action to malonic acid. It has also been found that the effects of the present invention cannot be obtained with these compounds.

  The inkjet recording reaction liquid of the present invention is preferably colorless, but may be light in a range that does not change the color tone of each color ink when mixed with a colored pigment ink on a recording medium. Furthermore, the various physical properties of the reaction solution in the present invention as described above are preferably set in the following ranges. Adjusted so that the pH is in the range of 1.0 to 6.0, the viscosity at 25 ° C. is in the range of 1 mPa · s to 30 mPa · s, and the surface tension is in the range of 28 mN / m to 52 mN / m. Is preferred.

  The ink set for ink-jet recording of the present invention is characterized by having at least a combination of a reaction liquid for ink-jet recording having the above-described configuration and a color pigment ink that causes a reaction by contact with the reaction liquid for ink-jet recording. In addition, the ink jet recording method of the present invention is characterized in that it is configured as follows using the reaction liquid for ink jet recording having the above configuration. The inkjet recording reaction liquid of the present invention is energized and discharged toward a recording medium, and after the reaction liquid is applied onto the recording medium or before it is applied, the colored pigment ink is energized toward the recording medium. And discharged onto the recording medium. At that time, the application is performed such that the recording reaction liquid and the color pigment ink are arranged in contact with each other on the recording medium. Hereinafter, the color pigment ink used above will be described.

[Colored pigment ink]
The colored pigment ink used in the present invention (hereinafter referred to as “pigment ink”) is not particularly limited as long as it causes a reaction by contact with the reaction liquid for ink jet recording of the present invention. Pigment inks used in ink jet recording can be used. The basic composition of pigment inks conventionally used for ink jet recording is that a pigment is dispersed in an aqueous liquid medium.

(Pigment)
As the pigment constituting the pigment ink, the same pigments as in the past can be used. Specific examples of the black pigment include carbon black. For example, carbon black produced by a furnace method or a channel method and having the following characteristics can be used. That is, the primary particle size is 15 nm to 40 nm, the specific surface area by BET method is 50 m ² / g to 300 m ² / g, DBP oil absorption is 40 ml / 100 g to 150 ml / 100 g, and the volatile content is 0.5% to 10%. % Or less and a pH value of 2 to 9, etc. are preferred.

  Examples of commercially available products having such characteristics include the following, and any of them can be preferably used. No. 2300, no. 900, MCF88, No. 33, no. 40, no. 45, no. 52, MA7, MA8, no. 2200B (manufactured by Mitsubishi Chemical Corporation). RAVEN 1255 (above Colombia). REGAL400R, REGAL330R, REGAL660R, MOGUL L (manufactured by Cabot). Color Black FWl, Color Black FW18, Color Black S170, Color Black S150, Printex 35, Printex U (manufactured by Degussa).

  Further, as the color pigment, those having a primary particle size of about 15 nm to about 300 nm are preferably used. Specific examples include the following, and any of them can be preferably used. Examples of yellow pigments include C.I. I. Pigment yellow 1, 2, 3, 13, 16, 17, 74, 83, 109, 110, 128, 138, 180 and the like. Examples of magenta pigments include C.I. I. Pigment Red 5, 7, 12, 48 (Ca), 48 (Mn), 57 (Ca), 112, 122, 254, C.I. I. Pigment violet 19 and the like. Examples of cyan pigments include C.I. I. Pigment Blue 1, 2, 3, 15: 3, 16, 22, C.I. I. Bat Blue 4 (CI Pigment Blue 60), 6 and the like. Of course, the present invention is not limited to these. In addition to the above, of course, newly produced pigments such as self-dispersing pigments can also be used. The pigment in the pigment ink used in the present invention is used in a mass ratio of 1% by mass to 20% by mass, preferably 2% by mass to 12% by mass with respect to the total mass of the pigment ink. Good.

(Dispersant)
In addition, the pigment ink used in the present invention may be one in which the pigments listed above are dispersed in a liquid medium with a dispersant as described below. As the pigment dispersant, any hydrophilic material may be used, and specific examples include hydrophilic resins and surfactants. Such a hydrophilic resin that functions as a pigment dispersant can be obtained by polymerizing monomers as raw materials. Specific examples of the monomer used at this time are not particularly limited, but those listed below can be used. For example, styrenes such as styrene, α-methylstyrene, 4-t-butylstyrene, 4-chloromethylstyrene, 4-styrenesulfonic acid and salts thereof. Vinyl naphthalenes such as 1-vinyl naphthalene and 2-vinyl naphthalene. (Meth) acrylic acid and salts thereof, methyl (meth) acrylate, ethyl (meth) acrylate, (n-butyl) (meth) acrylate, benzyl (meth) acrylate, 2-hydroxyethyl (meth) acrylate, (Meth) acrylic acids such as polyethylene glycol mono (meth) acrylate. Maleic acids such as maleic acid and its salts, dimethyl maleate and maleic anhydride. Itaconic acids such as itaconic acid and salts thereof, monomethyl itaconate and salts thereof, and dimethyl itaconate. Fumaric acids such as fumaric acid and its salts, dimethyl fumarate and the like. (Meth) acrylamides such as (meth) acrylamide, N-methylol (meth) acrylamide, 2-acrylamide-2-methylpropanesulfonic acid and salts thereof. N-vinylformamide, N-vinylacetamide, vinyl acetate, N-vinylpyrrolidone and the like can be mentioned. By copolymerizing using at least two of these monomers (at least one of which is a hydrophilic monomer or a monomer that becomes hydrophilic if subjected to appropriate treatment) An effective hydrophilic resin is obtained.

  The three-dimensional structure of the hydrophilic resin described above may be a block copolymer, a graft copolymer, or a random copolymer. Moreover, what is necessary is just to select a polymerization method suitably according to the monomer to be used, such as radical polymerization and ionic polymerization. Alternatively, natural resins such as rosin, shellac and starch can be preferably used. These resins are soluble in an aqueous solution in which a base is dissolved, and are alkali-soluble resins. The preferred weight average molecular weight is in the range of 1,000 to 30,000, more preferably in the range of 3,000 to 15,000. In addition, when using these hydrophilic resins as a pigment dispersant, it is preferable to contain them in a range of 0.1% by mass or more and 5% by mass or less based on the total mass of the pigment ink.

  In addition, the surfactant acting as a pigment dispersant is not particularly limited, and examples include anionic surfactants, cationic surfactants, amphoteric surfactants, nonionic surfactants, Any of those commonly used can be preferably used. Examples of the anionic surfactant that can be used in the present invention include the following. For example, fatty acid soaps having 12 to 18 carbon atoms such as laurate and myristate. Alkylbenzenesulfonates such as dodecylbenzenesulfonate. Alkyl naphthalene sulfonates such as isopropyl naphthalene sulfonate; Dialkyl sulfosuccinic acid ester salts such as di (2-ethylhexyl) sulfosuccinic acid ester salt. Sulfated oils. C12-18 higher alcohol sulfates such as dodecyl sulfate. Alkyl ether sulfates such as polyoxyethylene dodecyl ether sulfate; Polyoxyethylene alkylphenyl ether sulfates such as polyoxyethylene nonylphenyl ether sulfate. Alkyl ether phosphate salts such as polyoxyethylene dodecyl ether phosphate salts; And alkyl phosphate ester salts such as dodecyl phosphate ester salt and octadecyl phosphate ester salt.

  Examples of the cationic surfactant that can be used in the present invention include the following. For example, aliphatic amine salts having 8 to 24 carbon atoms such as octylamine salt, dodecylamine salt and stearylamine salt. Aliphatic quaternary ammonium salts such as octadecyltrimethylammonium chloride. Benzalkonium salts. Benzethonium salts. C12-18 pyridinium salts such as cetylpyridinium chloride. Such as imidazolinium salts.

  Examples of amphoteric surfactants that can be used in the present invention include the following. Examples thereof include carboxybetaines such as lauryldimethylbetaine, aminocarboxylic acid salts such as N-dodecylglycine, and imidazolinium betaines such as 2-dodecyl-N-carboxymethyl-N-hydroxyethylimidazolinium betaine.

  Examples of nonionic surfactants that can be used in the present invention include the following. For example, polyoxyethylene alkyl ethers having 12 to 22 carbon atoms such as polyoxyethylene lauryl ether and polyoxyethylene cetyl ether. Polyoxyethylene alkylphenyl ethers such as polyoxyethylene nonylphenyl ether. Polyoxyethylene adducts of acetylene diol. Polyoxyethylene polyoxypropylene block polymers and alkyl ethers thereof. Polyoxyethylene glycerin fatty acid esters. Polyoxyethylene sorbitan fatty acid esters. Polyoxyethylene sorbitol fatty acid esters. Polyethylene glycol fatty acid esters such as polyethylene glycol lauryl ester. And sorbitan fatty acid esters.

  These surfactants may be used alone or in appropriate combination of two or more. In particular, the dispersed pigment particles are negatively charged so that the surfactants and the above-described resin dispersants are appropriately used to have a preferable reactivity with the polyvalent metal salt in the reaction solution. It is preferable to design.

(PH adjustment)
The pigment ink containing the pigment and the dispersant as described above is preferably adjusted to be neutral or alkaline. In this way, it is possible to improve the solubility of the hydrophilic material used as the dispersant and to obtain a pigment ink that is further excellent in long-term storage stability. However, in this case, it may cause corrosion of various members used in the ink jet recording apparatus. Therefore, it is desirable that the pH is in the range of 7 to 10.

  Although it does not specifically limit as a pH adjuster used in this case, For example, the following can be used. Inorganic alkali agents such as various organic amines such as diethanolamine, triethanolamine and tetramethylammonium hydroxide, and alkali metal hydroxides such as sodium hydroxide, lithium hydroxide and potassium hydroxide. Organic acids such as acetic acid and lactic acid, and mineral acids such as hydrochloric acid, sulfuric acid, and nitric acid.

(Aqueous liquid medium)
A suitable aqueous liquid medium in the pigment ink used in the present invention is a mixed solvent of water and a water-soluble organic solvent, and the water-soluble organic solvent used by mixing with water is not particularly limited. Specifically, the following can be mentioned. For example, alkyl alcohols having 1 to 4 carbon atoms such as methyl alcohol, ethyl alcohol, n-propyl alcohol, isopropyl alcohol, n-butyl alcohol, sec-butyl alcohol, and tert-butyl alcohol. Amides such as N, N-dimethylformamide and N, N-dimethylacetamide, ketones such as acetone and diacetone alcohol, and ketoalcohols. Cyclic ethers such as tetrahydrofuran and dioxane. Ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 1,2-hexanediol, 1,6-hexane Glycols such as diol, diethylene glycol, triethylene glycol, and thiodiglycol. Lower alkyl ethers of polyhydric alcohols such as ethylene glycol monomethyl (or ethyl) ether, diethylene glycol monomethyl (or ethyl) ether, triethylene glycol monomethyl (or ethyl) ether. Polyalkylene glycols such as polyethylene glycol and polypropylene glycol. Triols such as glycerin, 1,2,6-hexanetriol, and trimethylolpropane. N-methyl-2-pyrrolidone, 2-pyrrolidone, 1,3-dimethyl-2-imidazolidinone and the like. These may be used alone or in combination of two or more. The content of these water-soluble organic solvents in the ink is not particularly limited, but is generally in the range of 3% by mass to 50% by mass of the total mass of the pigment ink, more preferably 3% by mass. It is the range of 40 mass% or less.

(Additive)
In addition to the above-described components, a surfactant, an antifoaming agent, a preservative, and the like can be appropriately added to the pigment ink in the present invention in order to obtain desired physical properties as necessary. In particular, the surfactant functioning as a penetration accelerator needs to be added in an appropriate amount to play a role of promptly penetrating the liquid components of the reaction liquid and the pigment ink into the recording medium. As an example of addition amount, 0.05 mass% or more and 10 mass% or less, Preferably 0.5 mass% or more and 5 mass% or less are suitable.

  Examples of the surfactant include an anionic surfactant, a cationic surfactant, an amphoteric surfactant, a nonionic surfactant, and the like, and any commonly used surfactant can be preferably used. As specific surfactants, any of those exemplified above as pigment dispersants can be used.

(Preparation method of pigment ink)
As a method for preparing a pigment ink made of the above materials, first, a pigment is added to an aqueous medium containing at least a hydrophilic material as a dispersant and water, and after mixing and stirring, a dispersion treatment is performed. Then, if necessary, a desired pigment dispersion is obtained by performing a centrifugal separation treatment. At this time, it is effective to perform premixing for 30 minutes or more before the dispersion treatment. That is, such a premixing operation is preferable because it improves wettability of the pigment surface and promotes adsorption of the dispersant on the pigment surface.

  The disperser used in the above-described pigment dispersion treatment may be any disperser that is generally used, and examples thereof include a ball mill, a roll mill, and a sand mill. Among these, a high speed type sand mill is preferably used. Examples thereof include a super mill, a sand grinder, a bead mill, an agitator mill, a glen mill, a dyno mill, a pearl mill, and a cobol mill (all are trade names).

  In addition, in the pigment ink used in the ink jet recording method, a fine pigment having an optimum particle size distribution is used because of demands such as clogging resistance. As a method for obtaining a pigment having a desired particle size distribution used in this case, the following method may be applied. That is, changing the size of the grinding media of the disperser, increasing / decreasing the filling rate of the grinding media, adjusting the processing time, classifying with a filter or centrifuge after grinding, and a combination of these methods Etc.

  Next, to the pigment dispersion obtained as described above, the above-mentioned aqueous liquid medium and the additive components as mentioned above are appropriately added as necessary, and stirred and used in the present invention. A pigment ink is used. In addition, various physical properties of the pigment ink used in the present invention are preferably in the following ranges. It is adjusted so that the pH is in the range of 5.0 to 10.0, the viscosity at 25 ° C. is in the range of 1.5 mPa · s to 30 mPa · s, and the surface tension is in the range of 28 mN / m to 52 mN / m. Are preferred.

  When the ink jet recording reaction liquid of the present invention obtained as described above is combined with the pigment ink to be used in combination, the following is preferred. That is, when these are combined, it is preferable that the combination has a difference in permeability to a recording medium used for image formation. Specifically, it is preferable to combine a set having different surface tension values. By doing so, the reaction liquid and the pigment ink can be sufficiently mixed on the recording medium, and then rapidly penetrated. In this way, it is possible to further improve not only color developability but also fixability for high-speed printing.

  Hereinafter, the present invention will be described more specifically with reference to Examples and Comparative Examples. In the following description, “part” or “%” is based on mass unless otherwise specified.

[Synthesis Example 1 (Preparation of pigment dispersion)]
-Random copolymer consisting of styrene-acrylic acid-ethyl acrylate (acid value 200, weight average molecular weight = 9,000) 1.4 parts-1.0 part monoethanolamine-5.0 parts diethylene glycol-Ion exchange water 81.6 parts

The above components are mixed and heated to 70 ° C. in a water bath to completely dissolve the resin component. To this solution, 10 parts of carbon black (FW18, manufactured by Degussa) and 1 part of isopropyl alcohol were added, premixed for 30 minutes, and then dispersed under the following conditions.
・ Disperser: Sand grinder (Igarashi Machine)
・ Crushing media: Zirconium beads, 1 mm diameter ・ Filling rate of grinding media: 50% (volume ratio)
-Grinding time: 3 hours Further, centrifugal treatment (12,000 rpm, 20 minutes) was performed to remove coarse particles to obtain a black (K) pigment dispersion.

[Synthesis Examples 2 to 4 (Preparation of pigment dispersion)]
Cyan (C), magenta (M), and yellow were treated in the same manner as in Synthesis Example 1 except that the carbon black (FW18, manufactured by Degussa) used in Synthesis Example 1 was replaced with the following pigments. Each color pigment dispersion of (Y) was obtained. That is, instead of carbon black, C.I. I. Pigment blue 15: 3, C.I. I. Pigment red 7 and C.I. I. Pigment Yellow 74 pigment was used.

<Production Example 1 (Preparation of Pigment Ink K1)>
Using the black pigment dispersion obtained in Synthesis Example 1, an ink containing a pigment was produced according to the following composition ratio to obtain a pigment ink. The surface tension of the obtained pigment ink was 38 mN / m.
-Pigment dispersion liquid of Synthesis Example 1-10.0 parts of glycerin-5.0 parts of ethylene glycol-1.0 part of acetylenol EH (manufactured by Kawaken Fine Chemicals)-54.0 parts of ion-exchanged water

<Production Example 2 (Preparation of Pigment Ink C1)>
A pigment ink C1 containing a pigment was prepared in the same manner as in Production Example 1 except that the cyan pigment dispersion obtained in Synthesis Example 2 was used instead of the pigment dispersion obtained in Synthesis Example 1. The obtained pigment ink had a surface tension of 37 mN / m.

<Production Example 3 (Preparation of Pigment Ink M1)>
A pigment ink M1 containing a pigment was prepared in the same manner as in Production Example 1, except that the magenta pigment dispersion obtained in Synthesis Example 3 was used instead of the pigment dispersion obtained in Synthesis Example 1. The surface tension of the obtained pigment ink was 36 mN / m.

<Production Example 4 (Preparation of Pigment Ink Y1)>
Pigment ink Y1 containing a pigment was prepared in the same manner as in Production Example 1, except that the yellow pigment dispersion obtained in Synthesis Example 4 was used instead of the pigment dispersion obtained in Synthesis Example 1. The obtained pigment ink had a surface tension of 37 mN / m.

<Production Example 5 (Preparation of Pigment Ink K2)>
Using the black pigment dispersion obtained in Synthesis Example 1, an ink containing a pigment was produced according to the following composition ratio to obtain a pigment ink. The surface tension of the obtained pigment ink was 51 mN / m.
-Pigment dispersion liquid of Synthesis Example 1-10.0 parts of glycerin-5.0 parts of ethylene glycol-0.1 part of acetylenol EH (manufactured by Kawaken Fine Chemicals)-54.9 parts of ion-exchanged water

<Production Example 6 (Preparation of Pigment Ink C2)>
A pigment ink C2 containing a pigment was prepared in the same manner as in Production Example 5, except that the cyan pigment dispersion obtained in Synthesis Example 2 was used instead of the pigment dispersion obtained in Synthesis Example 1. The surface tension of the obtained pigment ink was 49 mN / m.

<Production Example 7 (Preparation of Pigment Ink M2)>
A pigment ink M2 containing a pigment was prepared in the same manner as in Production Example 5 except that the magenta pigment dispersion obtained in Synthesis Example 3 was used instead of the pigment dispersion obtained in Synthesis Example 1. The surface tension of the obtained pigment ink was 49 mN / m.

<Production Example 8 (Preparation of Pigment Ink Y2)>
Pigment ink Y2 containing a pigment was prepared in the same manner as in Production Example 5 except that the yellow pigment dispersion obtained in Synthesis Example 4 was used instead of the pigment dispersion obtained in Synthesis Example 1. The surface tension of the obtained pigment ink was 48 mN / m.

<Production Example 9 (Production of Reaction Solution S1)>
-Diethylene glycol 10.0 parts-Calcium nitrate tetrahydrate 10.0 parts-Malonic acid 0.2 parts-Acetylenol EH (manufactured by Kawaken Fine Chemicals) 0.1 part-Ion-exchanged water 79.7 parts After dissolution, the mixture was further filtered under pressure through a membrane filter (manufactured by MILLIPORE) having a pore size of 0.22 μm, and the pH was adjusted to 4.0, thereby obtaining a reaction solution S1. The surface tension of the obtained reaction liquid was 35 mN / m.

<Production Example 10 (Production of Reaction Solution S2)>
-Diethylene glycol 10.0 parts-Calcium nitrate tetrahydrate 10.0 parts-Malonic acid 0.2 parts-Acetylenol EH (manufactured by Kawaken Fine Chemicals) 1.6 parts-Ion-exchanged water 78.2 parts Except for the above, after the same treatment as in Production Example 9, the pH was adjusted to 4.0 to obtain a reaction solution S2. The surface tension of the obtained reaction liquid was 31 mN / m.

<Production Example 11 (Production of Reaction Solution S3)>
-Diethylene glycol 10.0 parts-Magnesium nitrate hexahydrate 12.0 parts-Malonic acid 0.2 parts-Acetylenol EH (manufactured by Kawaken Fine Chemicals) 0.1 part-Ion-exchanged water 77.7 parts Except for the above, after the same treatment as in Production Example 9, the pH was adjusted to 5.0 to obtain a reaction solution S3. The surface tension of the obtained reaction liquid was 35 mN / m.

<Production Example 12 (Production of Reaction Solution S4)>
・ Diethylene glycol 10.0 parts ・ Calcium nitrate tetrahydrate 10.0 parts ・ Methylmalonic acid 0.2 parts ・ Acetylenol EH (manufactured by Kawaken Fine Chemicals) 0.1 part ・ Ion-exchanged water 79.7 parts Except having carried out, after processing similar to manufacture example 9, pH was adjusted to 4.0 and reaction liquid S4 was obtained. The surface tension of the obtained reaction liquid was 35 mN / m.

<Production Example 13 (Production of reaction solution S5)>
-Diethylene glycol 8.0 parts-Methyl alcohol 5.0 parts-Calcium nitrate tetrahydrate 8.0 parts-Malonic acid 0.2 parts-Acetylenol EH (manufactured by Kawaken Fine Chemicals) 0.1 part-Ion-exchanged water 78. 7 parts Except having set it as said component, pH was adjusted to 4.0 after the process similar to manufacture example 9, and reaction liquid S5 was obtained. The surface tension of the obtained reaction liquid was 34 mN / m.

<Production Examples 14 to 16 (Preparation of reaction solutions S6 to S8)>
Except that malonic acid was removed from each composition of the reaction liquids S1 to S3 obtained in Production Examples 9 to 11 and the decrease was changed to water, the reaction liquids S6 to S8 were prepared. In addition, the surface tension of the obtained reaction liquid was the same as the case where malonic acid was included.

<Production Example 17 (Production of Reaction Solution S9)>
・ Diethylene glycol 10.0 parts ・ Calcium nitrate tetrahydrate 10.0 parts ・ Citric acid 0.2 parts ・ Acetylenol EH (manufactured by Kawaken Fine Chemicals) 0.1 part ・ Ion-exchanged water 79.7 parts Except for the above, after the same treatment as in Production Example 9, the pH was adjusted to 4.0 to obtain a reaction solution S9. The surface tension of the obtained reaction liquid was 35 mN / m.

<Production Example 18 (Production of Reaction Solution S10)>
・ Diethylene glycol 10.0 parts ・ Calcium nitrate tetrahydrate 10.0 parts ・ Ammonium nitrate 0.2 parts ・ Acetylenol EH (manufactured by Kawaken Fine Chemicals) 0.1 part ・ Ion-exchanged water 79.7 parts After the same treatment as in Production Example 9, the pH was adjusted to 4.0 to obtain reaction solution S10. The surface tension of the obtained reaction liquid was 35 mN / m.

<Production Example 19 (Production of Reaction Solution S11)>
・ Diethylene glycol 10.0 parts ・ Calcium nitrate tetrahydrate 10.0 parts ・ Glutamic acid 0.2 parts ・ Acetylenol EH (manufactured by Kawaken Fine Chemicals) 0.1 part ・ Ion-exchanged water 79.7 parts After the same treatment as in Production Example 9, the pH was adjusted to 4.0 to obtain a reaction solution S11. The surface tension of the obtained reaction liquid was 36 mN / m.

[Example 1]
Inkjet drawing apparatus for evaluation study loaded with pigment inks K1, C1, M1, and Y1 obtained in Production Examples 1 to 4 and reaction liquid S1 obtained in Production Example 9 and plain paper (PPC paper manufactured by Canon Inc.): The following method was used for evaluation. On the plain paper, 5,000 sheets of an evaluation image pattern (ISO JIS-SCID No. 5 bicycle) were continuously printed with the above-described apparatus. At that time, the reaction liquid S1 was applied to the paper prior to the ink dots of all the pigment inks. As a printing condition, a recording head having a recording density of 1,200 dpi and a discharge volume of 4 pl per dot was used, and the driving condition was a driving frequency of 15 kHz. The environmental conditions for the print test were unified at a temperature of 25 ° C. and a relative humidity of 55%.

  As an evaluation method, bleeding of the obtained printed matter, that is, the color mixing degree of the portion where each colored ink was printed adjacently was visually observed, and at the same time, the color developability and the through-through property were also visually observed. As a result, even in the 5,000th printed image, no occurrence of bleeding was observed, and a clear printed matter was obtained. In addition, the color developability and back-through property of the black and color print portions were also very good as compared with the case where the reaction solution S1 was not applied.

[Examples 2 to 10]
The same evaluation as in Example 1 was performed for each combination of the pigment ink and the reaction liquid described in Table 1-1, and bleeding, color developability, and back-through property were visually evaluated in the same manner as in Example 1. The results are summarized in Table 1-1.

[Comparative Example 1]
A continuous printing test similar to that in Example 1 was conducted except that the reaction solution S6 obtained in Production Example 14 obtained by substituting malonic acid with water was used instead of the reaction solution S1 obtained in Production Example 9, and bleeding was performed. The evaluation including it was performed by visual observation of the printed matter. As a result, color unevenness derived from the difference in color developability began to occur at several locations in the image after 500 sheets had been printed, and the color developability of the entire image became poor after 700 sheets. Furthermore, at the time of 2,000 sheets, the image was not much different from the condition in which no reaction solution was used, so the further continuous printing test was stopped. This was considered to be because the discharge of the reaction liquid from the recording head was stopped. Thereafter, a recovery operation was attempted by means such as directly sucking the reaction liquid from the nozzle of the recording head, but the reaction liquid could not be discharged again from the nozzle that stopped discharging. Here, when the nozzle which stopped discharging was observed with a microscope, it was confirmed that the heater surface was greatly damaged.

[Comparative Examples 2 to 11]
The same evaluation as in Example 1 was performed for each combination of the pigment ink and the reaction liquid described in Table 1-2, and the bleeding, color developability, and back-through property were visually evaluated in the same manner as in Example 1. The results are summarized in Table 1-2.

  As described above, by using the ink jet recording reaction solution of the present invention together with the pigment ink, it is possible to obtain a high-quality color image with no bleeding on plain paper and good color development. At the same time, even if the reaction liquid is applied to the recording medium by the action of thermal energy, the ink-jet recording reaction liquid of the present invention does not impair the discharge characteristics. As a result, a clear and stable image is continuously obtained over a long period of time. And you can get it.

Claims (5)

  A reaction liquid for inkjet recording that is used together with a color pigment ink and that reacts when contacted with the color pigment ink, and includes (a) a polyvalent metal salt, (b) malonic acids, and (c) a liquid medium. A reaction liquid for ink jet recording characterized by the above.   The inkjet recording according to claim 1, wherein the malonic acid of (b) is a compound selected from malonic acid, methylmalonic acid, dimethylmalonic acid, ethylmalonic acid, diethylmalonic acid, butylmalonic acid, and salts thereof. Reaction solution.   An ink jet recording method using the ink jet recording reaction liquid according to claim 1, wherein energy is supplied to the ink jet recording reaction liquid and discharged toward the recording medium, and the reaction liquid is applied onto the recording medium. After applying or before applying, energy is applied to the colored pigment ink and discharged toward the recording medium to be applied onto the recording medium, and the recording reaction liquid and the colored pigment ink are applied to the recording medium. An ink jet recording method, wherein the ink jet recording method is performed so as to be in contact with each other.   The inkjet recording method according to claim 3, wherein the energy is thermal energy.   An ink set for ink-jet recording, comprising at least the reaction liquid for ink-jet recording according to claim 1 and a color pigment ink that reacts by contact with the reaction liquid for ink-jet recording.