JP2011062952A - Reaction liquid, set, inkjet recording method, and inkjet recorder - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a reaction liquid that restrains the occurrence of a surface damp feeling and curling of a recording medium, has excellent solid uniformity, and provides an excellent image quality restrained from the occurrence of feathering. <P>SOLUTION: The reaction liquid, which is applied to a recording medium by a roller coating system prior to recording with an ink containing a color material, has a function for destabilizing a dissolved or dispersed state of the coloring material in the ink by coming into contact with the ink, and contains at least a polyvalent metal halide, an acetylene glycol compound and a polyethylene glycol having an average molecular weight of 200-1,000. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a reaction liquid, a set of ink and the reaction liquid, an ink jet recording method using the reaction liquid, and an ink jet recording apparatus.

  Conventionally, as an inkjet recording method, various methods for recording an image by applying a liquid for improving image quality to a recording medium prior to the application of the ink, in addition to a normal inkjet ink, have been proposed. Yes. However, any of the conventional methods attempts to suppress image bleeding and improve the water resistance of an image by precipitating a dye on a recording medium. However, this technique can cause bleeding between a plurality of color inks. The effect of suppressing is insufficient. In addition, since the precipitated dye is likely to be unevenly distributed on the recording medium, the image quality may be less uniform. In particular, when plain paper or the like is used as the recording medium, this tendency may occur remarkably due to the low coverage of the deposited dye on the pulp fiber.

  Various methods have been proposed for solving the above-described problems and achieving improvement in image uniformity and image density. For example, there is a proposal relating to a method of recording a liquid composition containing polyvalent metal ions in advance on a recording medium and then recording with an ink having reactivity with the liquid composition (see, for example, Patent Document 1). However, using any of the conventional methods, it is not possible to obtain a high image density that satisfies the recent demand for higher image quality, or the image quality obtained after the initial time and time may differ. There was a thing.

  In addition, there is another problem different from the image quality in which the recording medium to which the ink is applied warps or curls so-called curl occurs. As a method for suppressing this curl, for example, there is a proposal regarding an ink-jet ink containing a solid substance having four or more hydroxyl groups in a molecular structure and being soluble in water or an aqueous organic solvent (Patent Document 2). As an anti-curl agent, there is a proposal regarding an ink containing saccharides, sugar alcohols, and a specific amide compound (Patent Document 3). There is also a proposal regarding an ink containing a combination of a specific polyhydric alcohol and glycerin (Patent Document 4).

JP 2000-94825 A JP-A-4-332775 JP-A-6-157955 JP-A-10-130550

  As a result of further studies by the present inventors, it has been clarified that solid image unevenness occurs due to a difference in wettability (surface energy difference) on the surface of the recording medium, particularly on the surface of plain paper. This unevenness means a state in which the color material does not stay on the surface of the recording medium in a part of the solid image region, and a spotted pattern such as white spots is visible. Hereinafter, an image state in which this phenomenon occurs is referred to as “solid uniformity is insufficient”, and an image in which this phenomenon does not occur is referred to as “solid uniformity”.

  The solid uniformity will be described in detail. First, the difference in wettability on the surface of plain paper occurs between the cellulose site that has been fibrillated and the dense cellulose site in the vicinity of the so-called conduit (also referred to as a vessel). Is low and difficult to get wet. When the reaction liquid is applied onto such plain paper, the reaction liquid is repelled in the portion where the surface energy is low, and conversely, it begins to penetrate into the plain paper while gathering in the portion where the surface energy around it is high. . Next, when an ink containing a color material is applied, since the component of the reaction liquid is substantially absent (small) in the portion where the surface energy is low, the cohesive action of the color material is exhibited after the ink is applied. Not. For this reason, the ink penetrates into the plain paper, or the ink moves to the surrounding area where the surface energy is high. On the other hand, in the portion where the surface energy is high, after the ink is applied, the color material aggregates and the color material stays near the surface of the recording medium. For these reasons, the solid uniformity is insufficient. Furthermore, for example, it has been found that the above phenomenon occurs more remarkably when the reaction liquid is applied to the entire surface of the recording medium by a coating roller or the like.

  In addition, when the surfactant content in the reaction liquid is increased for the purpose of improving the penetrability of the reaction liquid in contact with the ink in a liquid state into the recording medium, the recorded image is increased. It was found that feathering is likely to occur.

  Therefore, an object of the present invention is to obtain an image with excellent image quality that has good solid uniformity, curl generation in a recorded matter, and further occurrence of feathering is suppressed when used with ink. It is in providing the reaction liquid which can be performed. Another object of the present invention is to provide a set of ink and the reaction liquid, an ink jet recording method using the reaction liquid, and an ink jet recording apparatus that can obtain the excellent image.

  The above object is achieved by the present invention described below. That is, the reaction liquid according to the present invention is a reaction liquid applied to the recording medium by a roller coating method prior to recording of the ink containing the color material, and the color material in the ink is dissolved by contact with the ink. Or having a function of destabilizing the dispersion state, and containing at least a halogenated polyvalent metal, an acetylene glycol compound, and a polyethylene glycol having an average molecular weight of 200 or more and 1,000 or less. And

  According to the present invention, it is possible to obtain an image with excellent solid image quality and good image quality, and curling can be prevented from occurring in a recorded matter, and further, an image having excellent image quality with suppressed feathering can be obtained. A reaction solution for use with is provided. Further, according to another embodiment of the present invention, there are provided a set of an ink and the reaction liquid, an ink jet recording method using the reaction liquid, and an ink jet recording apparatus that enable the above-described excellent image formation. The

It is a schematic sectional side view which shows an example of an inkjet recording device.

  Hereinafter, the present invention will be described in more detail with reference to preferred embodiments of the present invention. In addition, the halogenated polyvalent metal contained in the reaction solution of the present invention exists in a state of being ionized into a polyvalent metal ion and a halogen ion in the reaction solution.

<Reaction solution>
The reaction liquid of the present invention is used in combination with an ink containing a color material when forming an image, and has a function of destabilizing the dissolution or dispersion state of the color material in the ink by contacting the ink. The constituent components are as follows. Specifically, it is essential to contain a halogenated polyvalent metal, an acetylene glycol compound, and polyethylene glycol having an average molecular weight of 200 to 1,000. Note that the dissolution or dispersion state of the coloring material in the ink is destabilized by the reaction liquid of the present invention when the polyvalent metal ion in the reaction liquid and the anionic component in the ink come into contact with each other. By reacting with each other. Examples of the anionic component in the ink include a pigment in which an anionic group is chemically bonded to the surface of the pigment particle, and an anionic resin dispersant.

  As described above, the wettability of the reaction liquid and the surface of plain paper has a great influence on the performance related to solid uniformity. In particular, the wettability between the reaction liquid and the plain paper surface is strongly influenced by the composition of the reaction liquid. In order to increase the wettability between the two, it is particularly effective to reduce the surface tension of the reaction solution. As a method for lowering the surface tension of a reaction solution, it is generally known to contain a surfactant in the reaction solution. However, as a result of investigations by the present inventors, it is not sufficient to optimize the surfactant content in the reaction solution in order to achieve both improvement in solid uniformity and suppression of feathering. .

  The reaction between the ink and the reaction liquid causes the dispersion or dissolution state of the color material in the ink to be unstable by contacting with the component that makes the color material in the dispersion or dissolution state, for example, an anionic component. This is a coagulation reaction with polyvalent metal ions such as calcium ions in the reaction solution to be converted. However, if the content of the surfactant in the reaction liquid is large, when the reaction liquid and the ink are mixed in the recording medium, the coagulated material generated by the coagulation reaction or the colorant in the process of the coagulation reaction When the surfactant is adsorbed on the surface, they are dispersed and stabilized in the mixed solution. As a result, as the liquid component penetrates into the surface direction and depth (thickness) direction of the recording medium, the coagulated material and the coloring material in the process of coagulation reaction diffuse to cause feathering. It becomes easy.

  For these reasons, it is preferable to lower the surface tension of the reaction liquid in order to improve the solid uniformity, but in order to suppress the occurrence of feathering, the surfactant content is First of all, it is possible to reduce as much as possible.

  As technical means for achieving the above idea, the present inventors have focused on anion species that are counter ions of the polyvalent metal ions to be used. As a general fact, in the case of an aqueous system, it is known that the surface tension increases as the electrolyte concentration in the system increases or as the number of molecules having many OH groups in the molecule increases. When the electrolyte is dissolved in water, if ions are generated and the attractive force between water and ions becomes stronger than the attractive force between water and water, the intermolecular force of water as a whole is increased. The surface tension is expected to increase. As a result of the examination by the present inventors, it has been clarified that the influence of this action varies depending on the anion species.

In particular, when the reaction liquid is applied to the recording medium by a roller coating method, the amount of the reaction liquid applied on the surface of the recording medium is 0.5 g / m ² or more and 3 g / m ² or less from the viewpoint of running cost and paper texture. Is preferred. In order to efficiently generate an agglomeration reaction in an ink to be recorded later in such an applied amount, it is preferable to contain a large amount of polyvalent metal ions. Specifically, for example, in the case of a calcium salt, the calcium ion concentration is preferably 2.7% by mass or more based on the total mass of the reaction solution, and at least the solubility does not exceed the saturation concentration even at the above concentration. It is assumed that Furthermore, considering the ease of maintenance of the recording apparatus to which the reaction liquid is applied, the calcium salt to be used needs to have a higher solubility. Is a candidate.

  Here, as a result of the study by the present inventors, it is possible to lower the surface tension of the reaction solution with a smaller amount of surfactant by using halide ions than using nitrate ions. It became clear. For this reason, the present inventors believe that the difference occurs because the state of solvation between the anion and water (and the water-soluble organic solvent used) differs depending on the anion species used.

  On the other hand, even when using a reaction liquid in which the amount of surfactant is adjusted using a halogenated polyvalent metal, although there is some progress in achieving both improvement in solid uniformity and suppression of feathering, it is still not at a sufficient level. I understood it. As a result of further studies, it was found that the problem can be solved by using polyethylene glycol in the reaction solution. This is considered to be due to the fact that the polyethylene glycol contained in the reaction liquid enhances the reactivity between the ink and the polyvalent metal ions when the reaction liquid is infiltrated and concentrated on the surface of the recording medium. ing. At the same time, as described in the technology disclosed above, polyethylene glycol has a strong curling suppressing effect, so that curling prevention of recorded matter can be achieved at the same time.

(Average molecular weight of polyethylene glycol)
As the polyethylene glycol contained in the reaction solution of the present invention, those having an average molecular weight of 200 or more and 1,000 or less are used. If the average molecular weight is less than 200, curling of the recorded material prepared by using the reaction solution and the ink together may not be suppressed, and although it depends on the mass ratio of the polyethylene glycol, the solid uniformity is improved and the feather is reduced. It may be difficult to achieve both suppression of ring generation. On the other hand, when the average molecular weight exceeds 1,000, the viscosity of the reaction liquid increases, so that the permeability of the reaction liquid to the recording medium decreases even when the surface tension of the reaction liquid is low. As a result, the recording medium There is a case where the feeling that the surface of the paint is painted (= moist feeling) cannot be suppressed. In the present invention, the average molecular weight of polyethylene glycol is more preferably 200 to 600. In addition, the average molecular weight of the polyethylene glycol in this invention includes the range of the upper and lower 30 of the value. For example, in the case of polyethylene glycol having an average molecular weight of 600, those having a molecular weight of 570 to 630 are assumed to have an average molecular weight of 600. More specifically, polyethylene glycol having an average molecular weight of 600 is defined as one having an average molecular weight of 570 to 630 determined by a measurement method described later.

The average molecular weight of the polyethylene glycol used in the present invention is a value measured as follows. 1 g of polyethylene glycol sample to be measured (weighed to the order of 0.1 mg) was put in 25 mL of anhydrous phthalpyridine solution accurately weighed with a flask with a stopper, stoppered and heated in a boiling water bath for 2 hours. Let stand until room temperature. Thereafter, 50 mL of 0.5 mol / L aqueous sodium hydroxide solution (weigh accurately) and 10 drops of a phenolphthalein solution for titration are placed in the flask. The liquid in the flask is titrated with a 0.5 mol / L sodium hydroxide aqueous solution, and the end point is the point at which the liquid remains red for 15 seconds. From the titration amount M (mL) of the test thus obtained and the titration amount R (mL) obtained by the blank test conducted in the same manner as above except that no polyethylene glycol sample was used, the following formula was obtained. Based on this, the average molecular weight is calculated.

(Polyethylene glycol content)
The content of polyethylene glycol used in the reaction solution of the present invention is not particularly limited, and can be within the following content ranges. The content (% by mass) of polyethylene glycol in the reaction solution is preferably 4.0% by mass or more and 30.0% by mass or less based on the total mass of the reaction solution. Furthermore, it is more preferable to set it to 10.0 mass% or more and 25.0 mass% or less, especially 15.0 mass% or more and 20.0 mass% or less.

(Polyvalent metal ions and their contents)
Although content (mass%) of the polyvalent metal ion in the reaction liquid of this invention is not specifically limited, It is preferable that they are 67 mmol or more and 107 mmol or less per 100 g of reaction liquid. When the content of the polyvalent metal ion is less than 67 mmol per 100 g of the reaction solution, feathering in an image recorded by using the reaction solution and the ink together may not be suppressed. On the other hand, even if the content exceeds 107 mmol, it does not particularly affect the image recorded by using the reaction liquid and the ink in combination, but even if the content of polyvalent metal ions is further increased. Also, a positive effect cannot be obtained. Examples of the polyvalent metal ion that can be used in the present invention include Mg ²⁺ , Sr ²⁺ , Ca ²⁺ , Al ³⁺ , Y ^3+, etc., but considering the performance and cost, Ca ^{2 +} Is particularly preferred.

In the present invention, in order to contain a polyvalent metal ion in the reaction solution, a water-soluble compound in which the polyvalent metal ion is bonded to an anion, particularly a halogen ion, that is, a water-soluble polyvalent metal halide salt is added to the reaction solution. It is good to add to. When the water-soluble polyvalent metal salt is added in this way, at least a part of the polyvalent metal salt is dissociated into polyvalent metal ions and anions in the reaction solution. Specific examples of the halogen ions used in the present ^{invention, Cl -, I -, Br} - , and the like. Among these, Cl ⁻ and Br ⁻ are particularly preferable from the viewpoint that the reaction solution is not colored, and more preferably Br ⁻ is used in that corrosion to the metal in contact with the reaction solution hardly occurs.

(Acetylene glycol compound)
In the reaction solution of the present invention, it is necessary to reduce the surface tension at a low concentration, the surface tension decreases in a short time of several milliseconds in terms of dynamic surface tension, and furthermore, the foaming property is low. From the above viewpoint, an acetylene glycol compound is used as the surfactant. In the present invention, for example, an acetylene glycol ethylene oxide adduct (specifically, acetylenol E100; manufactured by Kawaken Fine Chemical Co., Ltd.) is used as the acetylene glycol compound. At that time, the content (% by mass) of the compound is preferably as follows. Specifically, the content (% by mass) of the acetylene glycol compound in the reaction solution is preferably 0.40% by mass or more and 1.2% by mass or less based on the total mass of the reaction solution.

  As low-foaming surfactants other than acetylene glycol compounds, there are polyoxyethylene alkyl ethers, which are not preferable in the following respects as compared with acetylene glycol compounds. That is, the foaming ability is strong, the effect of improving the solid uniformity due to the low ability to lower the surface tension in a short time, and the adsorption of the pigment to be recorded later is strong due to the structure of the surfactant. The deterioration of the character quality due to this.

(Reaction liquid surface tension)
The surface tension of the reaction solution of the present invention is preferably determined appropriately depending on the type of surfactant used. In the present invention, for example, when an acetylene glycol ethylene oxide adduct (specifically, acetylenol E100; manufactured by Kawaken Fine Chemical Co., Ltd.) is used as the surfactant, the surface tension of the reaction solution is 27 mN / m or more and 31 mN / m. The following is preferable. The surface tension of the reaction solution is a value measured by a conventional method at a temperature of 25 ° C.

(Buffering agent)
In addition to the above components, the reaction solution of the present invention preferably contains a compound having a buffering action against a change in pH, that is, a buffering agent. The reaction solution has a buffering action against a change in pH, which is particularly preferable from the viewpoint that the change in pH that is likely to occur when components in the reaction solution evaporate is suppressed and the stability of the reaction solution is maintained. . The content (% by mass) of the buffer in the reaction solution is preferably 0.1% by mass or more and 1.0% by mass or less based on the total mass of the reaction solution.

  As the buffer, for example, polyvalent carboxylates such as acetate, hydrogen phosphate, hydrogen carbonate, hydrogen phthalate, and the like can be used. Specific examples of the polyvalent carboxylic acid include malonic acid, maleic acid, succinic acid, fumaric acid, itaconic acid, phthalic acid, isophthalic acid, terephthalic acid, adipic acid, sebacic acid, dimer acid, Examples include pyromellitic acid and trimellitic acid.

  Examples of the acetate that can be used include sodium acetate, potassium acetate, and lithium acetate. Examples of the hydrogen phosphate that can be used include sodium hydrogen phosphate, potassium hydrogen phosphate, and lithium hydrogen phosphate. it can. Moreover, as a hydrogencarbonate, sodium hydrogencarbonate, potassium hydrogencarbonate, lithium hydrogencarbonate etc. can be used, for example. As the polyvalent carboxylate, hydrogen phthalate will be described as an example. For example, sodium hydrogen phthalate, potassium hydrogen phthalate, lithium hydrogen phthalate and the like can be used, and similarly listed above. A salt of a polyvalent carboxylic acid can be used.

  As long as it is a compound that can suppress a change in pH of the reaction solution by adding it, any compound having a buffering action against a change in pH known in the art can be used. Can be used for liquids. However, in the present invention, an acetate salt, particularly lithium acetate is preferably used as a buffering agent because it exhibits a buffering action in a pH range suitable for the pH of a reaction solution used in combination with ink.

(Aqueous medium)
In addition to the components described above, the reaction solution preferably contains water or an aqueous medium that is a mixed solvent of water and a water-soluble organic solvent. The content of water or the water-soluble organic solvent in the reaction solution may be within a range in which the effects of adding these can be obtained and the objective effects of the present invention are not impaired. Specifically, the content (% by mass) of the water-soluble organic solvent in the reaction solution is preferably 16.2% by mass or more and 60.0% by mass or less based on the total mass of the reaction solution. More preferably, it is 20.0 mass% or more and 50.0 mass% or less. The range of the content of the water-soluble organic solvent includes the polyethylene glycol described above. Specifically, as the other water-soluble organic solvent, for example, the following water-soluble organic solvents can be used. These water-soluble organic solvents may be used alone or in combination of two or more. However, glycerin can coexist with formic acid, which is a storage degradation component of polyethylene glycol, which is an essential component of the present invention, for high-temperature storage. May turn slightly yellow. For this reason, when the reaction solution storage container is transparent, it may be preferable not to use glycerin because the color of the reaction system is expected to change for each container.

  Monohydric alcohols having 1 to 4 carbon atoms, 1,5-pentanediol, 1,2-hexanediol, 1,6-hexanediol, 1,2,6-hexanetriol, trimethylolpropane, trimethylolethane, etc. Polyhydric alcohols. Amides, ketones or ketoalcohols, ethers, polyalkylene glycols having an average molecular weight exceeding 1,000, and alkylene glycols having an alkylene group of 2 to 6 carbon atoms. Examples include thiodiglycol, alkyl ether acetate, alkyl ethers of polyhydric alcohol, N-methyl-2-pyrrolidone, 2-pyrrolidone, 1,3-dimethyl-2-imidazolidinone. Among these, it is particularly preferable to use a polyhydric alcohol other than glycerin.

  Moreover, it is preferable to use deionized water as water. The water content (% by mass) in the reaction solution is preferably 40.0% by mass or more and 90.0% by mass or less based on the total mass of the reaction solution.

(Color of reaction solution)
Since the reaction liquid of the present invention is used for recording an image in combination with ink, it is preferable not to contain a coloring material. Further, considering the influence on the image, the reaction liquid absorbs in the visible region. It is particularly preferred that it is colorless and does not have any. Of course, the reaction solution of the present invention is not limited to having no absorption in the visible range, and even if it has absorption in the visible range, it is light in color as long as it does not affect the image. There may be.

(Other ingredients)
In the reaction solution of the present invention, in order to obtain a reaction solution having the above-mentioned physical properties, the effects of adding these can be obtained, and within the range not impairing the object effect of the present invention, In addition, other additives may be added. Specific examples of such additives include antifoaming agents, preservatives, and antifungal agents.

<Ink>
The reaction liquid of the present invention is used together with an ink containing a color material. The reaction liquid of the present invention is preferably used for image recording in combination with an ink containing a coloring material in a state of being dispersed or dissolved in an aqueous medium by the action of an ionic group. Give effect. Examples of the ink that can be suitably used in the present invention include an ink containing a pigment as a coloring material. The reaction liquid of the present invention is used for image recording in combination with an ink in which a pigment is stably dispersed in an aqueous medium by an ionic group, so that the state of dissolution or dispersion of the coloring material is destabilized. Color material aggregates are formed on the recording medium, enabling high-quality image recording.

(Pigment)
As the pigment, a resin dispersion type pigment (resin dispersion type pigment) in which the pigment is dispersed using a dispersant, or a self dispersion type pigment (self dispersion type pigment) in which a hydrophilic group is introduced on the surface of the pigment particle is used. be able to. In addition, pigments (resin-bonded self-dispersing pigments) in which organic groups containing a polymer are chemically bonded to the surface of pigment particles, microcapsule pigments, colored fine particles, and the like can be used. In the present invention, it is particularly preferable to use a pigment in which an anionic group is chemically bonded to the surface of the pigment particle or a pigment dispersed with an anionic resin dispersant (hereinafter referred to as a dispersant). Of course, these pigments having different dispersion methods may be used in combination. The pigment content (% by mass) in the ink is 0.1% by mass or more and 15.0% by mass or less, and further 1.0% by mass or more and 10.0% by mass or less based on the total mass of the ink. Is more preferable. Furthermore, for the purpose of adjusting the color tone of the ink, a conventionally known dye may be added as a coloring material in addition to the pigment.

  For black ink, it is preferable to use carbon black such as furnace black, lamp black, acetylene black and channel black as a pigment. For example, any of various commercially available products such as conventionally known ink jet recording can be used.

  In addition, not only commercially available products, but also newly prepared carbon black can be used. Not limited to carbon black, magnetic fine particles such as magnetite and ferrite, titanium black and the like are used as pigments for black ink. Also good. In addition, various known organic pigments for ink-jet recording can be used for the color ink.

(Dispersant)
When the carbon black or organic pigment mentioned above is used as the pigment, a dispersant can be used in combination. As the dispersant, those capable of dispersing the above pigment in an aqueous medium by the action of an anionic group are suitable. Specific examples include the following. Styrene-acrylic acid copolymer, styrene-maleic acid copolymer, styrene-methacrylic acid copolymer, vinyl naphthalene-acrylic acid copolymer, vinyl naphthalene-maleic acid copolymer, styrene-maleic anhydride Acid-maleic acid half ester copolymer. Or these salts.

  The resin used as the dispersant preferably has a weight average molecular weight of 1,000 to 30,000, more preferably 3,000 to 15,000. Further, in order to achieve both ink reliability such as ejection stability and storage stability and reactivity between the ink and the reaction liquid, the acid value thereof is 300 mgKOH / g or less, and further 100 mgKOH / g or more and 300 mgKOH. / G or less is preferable. Further, for the same reason as the above acid value, the content (mass%) of the dispersant in the ink is based on the content (mass%) of the color material in the ink (dispersant content / color material). Content) of 0.1 to 3 times, and more preferably 0.2 to 2 times.

  From the viewpoint of reliability as an ink, increasing the acid value of the dispersant or increasing its content tends to increase the stability of the ink with respect to the reaction liquid. In that case, excellent image performance can be obtained by increasing the content of polyvalent metal ions such as calcium ions in the reaction solution of the present invention, but the pH of the reaction solution tends to be lowered. For this reason, in this case, the content of the compound having a buffering action in the reaction solution is preferably increased as necessary.

(Self-dispersing pigment)
When carbon black or organic pigments mentioned above are used as pigments, they can be dispersed in an aqueous medium without using a dispersant by bonding ionic groups (anionic groups) to the surface of the pigment particles. Pigments that can be used, that is, self-dispersing pigments can also be used. An example of such a pigment is self-dispersing carbon black. Examples of the self-dispersing carbon black include carbon black in which an anionic group is bonded to the particle surface. Hereinafter, although anionic carbon black is demonstrated, it is not restricted to this, A self-dispersion type organic pigment can also be used.

As the anionic carbon black, on the surface of the carbon black particles, for example, at least one selected from the group consisting of —COOM, — (COOM) ₂ , —SO ₃ M, —PO ₃ HM, and —PO ₃ M ₂ is used. The thing which couple | bonded the anionic group is mentioned. In the above formula, each M is independently a hydrogen atom, an alkali metal, ammonium, or organic ammonium. Among these, carbon black in which —COOM, — (COOM) ₂ , and —SO ₃ M are bonded to the surface of the carbon black particles to be anionic is particularly preferable because of excellent dispersibility in the ink. is there.

(Colored fine particles / microcapsule type pigment)
As the coloring material of the ink, in addition to the above-mentioned materials, pigments microencapsulated with a resin, colored fine particles in which the periphery of the resin particles is coated with a coloring material, and the like can be used. The microcapsules inherently have dispersibility in an aqueous medium, but in order to further improve the dispersion stability, a dispersant as described above may be further added to the ink. Moreover, when using colored fine particles as a colorant, it is preferable to use a dispersant as described above.

(Aqueous medium)
For the ink, water or an aqueous medium that is a mixed solvent of water and a water-soluble organic solvent can be used. In addition, when ink is applied to a recording medium by an ink jet method (for example, bubble jet (registered trademark) method), the ink has a desired viscosity and surface tension so as to have excellent ink jet discharge characteristics. It is preferable to adjust to.

  The content (% by mass) of the water-soluble organic solvent in the ink is preferably 3.0% by mass or more and 50.0% by mass or less based on the total mass of the ink. As the water-soluble organic solvent, it is particularly preferable to use a solvent that can suppress drying of the ink. For example, the same water-soluble organic solvent as that used in the reaction solution described above can be used, and the water-soluble organic solvent may be used alone or in combination of two or more. Moreover, it is preferable to use deionized water as water. The content (% by mass) of water in the ink is preferably 50.0% by mass or more and 95.0% by mass or less based on the total mass of the ink.

(Other ingredients)
In addition to the above components, a moisturizing agent and the like are added to the ink as necessary. In addition, a surfactant, an antifoaming agent, an antiseptic, an antifungal agent, and the like are used to obtain an ink having desired physical properties. May be added. The pH of the ink is preferably 6 or more and 10 or less, more preferably 7 or more and 9 or less. Further, in the present invention, since the ink and the reaction liquid are reacted more effectively, the uniformity of the solid image can be improved and the back-through can be suppressed, so that the pH of the reaction liquid is lower than the pH of the ink. Is particularly preferred.

<Set of ink and reaction liquid>
The set of the present invention has the reaction liquid of the present invention and the ink described above. The color tone of the ink is not particularly limited, and may be an ink having one color tone selected from yellow, magenta, cyan, red, green, blue, and black, for example. Specifically, the ink can be appropriately selected from conventionally known color materials so that the ink has a desired color tone. Moreover, the ink combined with the reaction liquid is not limited to one type, and an embodiment in which two or more different inks are combined to form an ink set suitable for recording a multicolor image is more preferable. In this case, it is sufficient that at least one of the two or more types of ink reacts with the reaction liquid.

  For example, if one kind of ink in which a color material is dispersed in an aqueous medium by the action of an ionic group is used, the other ink may be an ink containing a dye as a color material. Of course, all the inks constituting the ink set may be inks in which the color material is dispersed in the aqueous medium by the action of ionic groups. By using the set of the present invention having such a configuration, it is possible to suppress the occurrence of bleeding when inks of different color tones are applied adjacently on a recording medium, which is a problem when recording a multicolor image. Can do.

  In the present invention, the following set is more preferable. When recording a multicolor image, bleeding between black ink and other color inks (for example, at least one ink selected from yellow, magenta, cyan, red, green, and blue inks) occurs. It is particularly noticeable. Therefore, as the ink whose color material is dissolved or dispersed in an unstable state by contact with the reaction liquid of the present invention, a black ink in which a pigment is dispersed in an aqueous medium by the action of an ionic group is used. preferable. In this case, the other color ink may be an ink containing a dye as a coloring material. Of course, all the other inks may be inks in which a coloring material is dispersed in an aqueous medium by the action of an ionic group in the same manner as the black ink.

<Inkjet recording method and inkjet recording apparatus>
The reaction liquid of the present invention is used together with an ink containing a color material, but the ink is preferably applied to a recording medium by an ink jet recording method. In the recording medium, the region to which the reaction liquid is applied preferably includes at least a region to which ink is applied, and more preferably applied to the entire region of the recording medium. More specifically, the reaction liquid may be applied to the recording medium with an application roller so that the ink and the reaction liquid are in contact with each other so as to include at least a region where ink is applied to the recording medium.

The amount of the reaction liquid of the present invention applied to the recording medium may be appropriately determined depending on the content of polyvalent metal ions in the reaction liquid and the configuration of the ink to be reacted. In particular, in the present invention, since the uniformity and fixability of a solid image can be improved, the amount of reaction liquid applied to the recording medium is preferably 0.5 g / m ² or more and 3 g / m ² or less. Further, the lower limit of the amount of the reaction liquid applied to the recording medium is 1 g / m ² or more, more preferably 1.6 g / m ² or more, and particularly preferably 2 g / m ² or more. The upper limit of the amount of reaction solution applied to the recording medium is more preferably 2.4 g / m ² or less. In addition, when the area | region which applies a reaction liquid is only a certain part with respect to the magnitude | size (area: m < ² >) of a recording medium, it is assumed that it apply | coated to the whole surface of a recording medium, and the application amount of a reaction liquid It is preferable that the value (g / m ² ) is obtained and this value satisfies the above range.

  In the inkjet recording method of the present invention, when applying the reaction liquid to the recording medium, a roller coating method is used in which coating is performed with a coating roller prior to ink recording. For this reason, according to the ink jet recording method of the present invention, it is not necessary to consider the discharge property of the reaction liquid, and the reaction liquid can be effectively applied to the recording medium.

  Hereinafter, an example of the configuration of the inkjet recording apparatus of the present invention will be described with reference to the drawings. FIG. 1 shows an example of an ink jet recording apparatus of the present invention. Ink is applied to a recording medium by an ink jet method, and a reaction liquid is applied to a recording medium by an application roller.

  The ink jet recording apparatus of FIG. 1 employs a serial type ink jet recording method, and includes a recording head 1, a paper feed cassette 16, driving means for reciprocating the recording head in a direction orthogonal to the recording medium conveyance direction, Control means for controlling driving of the component is provided. The paper feed cassette 16 is integrally formed with a paper feed tray 17 for feeding the recording medium 19 and an application means for applying the reaction liquid of the present invention. The reaction liquid is applied to the recording medium 19 fed from the paper feed tray 17 with a uniform and adjusted coating amount. Details of the means for applying the reaction liquid to the recording medium (reaction liquid coating means) will be described later.

  The recording head 1 is mounted on the carriage 2 so that the surface on which the discharge ports are formed is oriented toward the platen 11. Although not shown, the recording head 1 includes the ejection port, a plurality of electrothermal transducers (for example, heating resistance elements) for heating ink, and a substrate that supports the electrothermal transducer. Note that an ink cartridge including an ink storage portion for storing ink is mounted inside the carriage on which the recording head 1 is mounted.

  The carriage 2 carries the recording head 1 and can reciprocate along two guide shafts 9 extending in parallel along the width direction of the recording medium 19. The recording head 1 is driven in synchronism with the reciprocating movement of the carriage 2 and ejects (applies) ink to the recording medium 19 to record an image.

  The paper feed cassette 16 can be detached from the ink jet recording apparatus main body. The recording medium 19 is stacked and stored on a paper feed tray 17 in the paper feed cassette 16. When paper is fed, the uppermost sheet is pressed against the paper feed roller 10 by a spring 18 that presses the paper feed tray 17 upward. The sheet feeding roller 10 is a roller having a substantially meniscus cross section, is driven and rotated by a motor (not shown), and feeds only the uppermost sheet (recording medium 19) by a separation claw (not shown).

  The separated and fed recording medium 19 is moved along the conveyance surface 16A of the paper feed cassette 16 and the conveyance surface 27A of the paper guide 27 by the large-diameter intermediate roller 12 and the small-diameter application roller 6 in pressure contact therewith. Are transported. These transport surfaces are formed by curved surfaces that draw a concentric arc concentric with the intermediate roller 12. Therefore, the fed recording medium 19 passes through these transport surfaces 16A and 27A, thereby reversing the transport direction. That is, the surface on which the recording medium 19 is recorded is directed downward until it is conveyed from the paper feed tray 17 and reaches the intermediate roller 12. Turn to the head side. Therefore, the recording surface of the recording medium always faces the outside of the ink jet recording apparatus.

  In the apparatus of FIG. 1, means for applying a reaction liquid to a recording medium (reaction liquid application means) is provided in the paper feed cassette 16. The reaction liquid application means is disposed so as to be parallel to the replenishment tank 22 for supplying the reaction liquid 15, the supply roller 13 that is rotatably supported with a part of the peripheral surface immersed therein, and the supply roller 13. And it has the application roller 6 which contacts the supply roller 13 and rotates to the same direction. The application roller 6 is arranged so that the intermediate roller 12 for conveying the recording medium 19 is in contact with and parallel to the peripheral surface. Therefore, when the recording medium 19 is transported, the intermediate roller 12 and the application roller 6 rotate with the rotation of the intermediate roller 12. As a result, the reaction liquid 15 is supplied to the peripheral surface of the application roller 6 by the supply roller 13, and the reaction liquid is evenly applied to the recording surface of the recording medium 19 sandwiched between the application roller 6 and the intermediate roller 12. Applied by. Reference numeral 20 denotes an inlet for injecting the reaction solution into the replenishing tank 22.

  The recording medium 19 on which the reaction liquid 15 has been applied by the above-described reaction liquid coating means is then fed to the recording section by a predetermined amount by the main transport roller 7 and the pinch roller 8 that is in pressure contact therewith, and the recording head Ink is applied from 1. The recording medium 19 fed and recorded in the above configuration is discharged and conveyed by the discharge roller 3 and the spur 4 in pressure contact with the discharge roller 3 and stacked on the discharge tray 5.

  In the present invention, since the reaction liquid 15 is applied by a roller or the like, the viscosity of the reaction liquid 15 is preferably higher than the viscosity of the ink. In this way, even if the application amount of the reaction liquid 15 is small, it can react efficiently with the ink and is also suitable for fixability and the like, which is preferable. More specifically, when the viscosity of the reaction liquid is higher than the viscosity of the ink, polyvalent metal ions such as calcium ions in the reaction liquid are more likely to stay near the surface of the recording medium, and react more efficiently with the ink. It becomes easy to do. On the other hand, after the ink reacts with the reaction liquid, the coloring material in the ink stays near the surface of the recording medium, and the aqueous medium in the ink quickly penetrates in the depth (thickness) direction of the recording medium. It is particularly preferable that the solid-liquid separation is performed quickly. For this reason, it is preferable that the viscosity of the ink is relatively low from the viewpoint of the fixability of the recorded matter.

  Specifically, when the reaction solution is applied to the recording medium with an application roller, the viscosity of the reaction solution is preferably 3 mPa · s or more and 100 mPa · s or less, and more preferably 4 mPa · s or more and 60 mPa · s or less. More preferably. On the other hand, the viscosity of the ink is preferably 1 mPa · s or more and 15 mPa · s or less. Setting the viscosity of the ink in this manner is also preferable from the viewpoint of ink jet ejection characteristics, particularly ink ejection stability. In the present invention, the viscosity of the reaction liquid or ink is a value measured by a conventional method at a temperature of 25 ° C.

  In this embodiment, in order to make the reaction liquid and the ink come into efficient contact with each other and to make them easily react, the ink is applied to the recording medium by the inkjet method after the reaction liquid is applied to the recording medium by the roller coating method. In this case, in order to sufficiently obtain the reactivity between the reaction liquid and the ink, the time interval from application of the reaction liquid to the recording medium to application of the ink is 1-2 seconds to 2-3 minutes. It is preferable that

In the present invention, the reaction liquid is applied to the recording medium by the roller coating method and the ink is applied to the recording medium by the inkjet method. The order of applying these to the recording medium is the following methods (a) and (b), and these methods: The combination of these can be mentioned and can be selected as appropriate.
(A): Ink is applied after the reaction solution is applied.
(B): The ink is applied after the reaction liquid is applied, and the reaction liquid is further applied.

  EXAMPLES Hereinafter, although an Example and a comparative example are given and this invention is demonstrated further more concretely, this invention is not limited to these, unless the summary is exceeded. In the following description, “%” and “part” are based on mass unless otherwise specified. In addition, the surface tension of the reaction solution was measured using CBVP-A3 (manufactured by Kyowa Interface Science) at a temperature of 25 ° C. Moreover, the average molecular weight of the used polyethylene glycol is a value obtained by measurement by the above-described method.

<Preparation of reaction solution>
Each component shown in Table 1 below was mixed and sufficiently stirred, and then pressure filtered through a microfilter (manufactured by Fuji Film) having a pore size of 0.2 μm to prepare each reaction solution. Table 1 below also shows the value of the surface tension of each reaction solution.

(* 1) Acetylene glycol / ethylene oxide adduct (addition number of ethylene oxide units = 10 mol; manufactured by Kawaken Fine Chemicals)
(* 2) Acetylene glycol / ethylene oxide adduct (addition number of ethylene oxide units = 7 mol; manufactured by Kawaken Fine Chemicals)
(* 3) Polyoxyethylene cetyl ether (addition number of ethylene oxide units = 20 mol; manufactured by Nikko Chemicals)

<Preparation of ink>
A black ink was prepared according to the following procedure as an ink to be used with the reaction solution.
10 parts of carbon black (trade name: Nipex 170; manufactured by Degussa), 40 parts of a dispersant (resin solid content: 8 parts), and 50 parts of pure water were mixed. As a dispersant, an anionic resin (benzyl methacrylate-methacrylic acid copolymer) having an acid value of 150 mgKOH / g and a weight average molecular weight of 8,000 is neutralized with potassium hydroxide, and the resin solid content is 20%. An aqueous solution was used. This mixture was put into a batch type vertical sand mill (manufactured by IMEX), filled with 150 parts of 0.3 mm diameter zirconia beads, and dispersed for 5 hours while cooling with water. The resulting dispersion was centrifuged to remove coarse particles and obtain a pigment dispersion. The solid content in the obtained pigment dispersion was 18% (pigment content: 10%, resin content: 8%), and the average particle size of the pigment was 95 nm.

  Using the pigment dispersion obtained above, each component of the following ink composition was mixed to prepare a black ink containing carbon black as a coloring material. The resulting black ink had a pigment content of 3%, a resin content of 2.4%, and an ink viscosity of 2.4 mPa · s.

(Ink composition)
・ Pigment dispersion 30.0%
・ Glycerin 10.0%
・ 2-pyrrolidone 2.5%
・ Polyethylene glycol (average molecular weight: 1,000) 2.0%
・ Acetylenol E100
(Surfactant: acetylene glycol ethylene oxide adduct;
Kawaken Fine Chemicals) 0.3%
・ Water 55.2%

<Evaluation>
(Solid uniformity)
The following color ink and each reaction liquid were combined to form a set, and an image was recorded using these sets. Cyan ink extracted from PGI-2 Cyan (manufactured by Canon) and magenta ink extracted from PGI-2 Magenta (manufactured by Canon) are mounted on the cyan and magenta ink positions of the ink jet recording apparatus BJS700 (manufactured by Canon). did. First, each reaction solution was applied to a recording medium 1 (trade name: office planner; manufactured by Canon) and a recording medium 2 (trade name: Xerox 4024; manufactured by Xerox), respectively, with an application roller. In this case, the application amount of the reaction liquid was 2 g / m ² . Immediately after that, solid images of secondary colors were respectively recorded with magenta ink and cyan ink on two types of recording media coated with the reaction liquid. The obtained recorded matter was visually observed, and the solid uniformity was evaluated according to the following criteria. The evaluation results are shown in Table 2. The “PGI-2” described above is an ink having such a property that the dissolved or dispersed state of the coloring material is destabilized by contact with the reaction liquid.
A: Although there are some white spots in the recording medium 2, generally good solid uniformity can be realized.
B: Although the white missing portion in the recording medium 2 is conspicuous, there are some white missing portions in the recording medium 1.
C: Not only the portion of the recording medium 2 that is white is noticeable, but also the portion of the recording medium 1 that is white is conspicuous.

(Feathering)
The black ink obtained above and each reaction solution were combined to form a set, and an image was recorded using these sets. The ink cartridge filled with the black ink was mounted on the black ink position of the ink jet recording apparatus (trade name: BJS700; manufactured by Canon Inc.). First, each reaction solution was applied to a recording medium (trade name: SW-101; manufactured by Canon) with an application roller. In this case, the application amount of the reaction liquid was 2 g / m ² . Immediately thereafter, 36-point characters and ruled lines were recorded on the recording medium coated with the reaction solution by the ink jet recording apparatus. Thereafter, the radiance values of characters and ruled line edges were measured using Personal IAS (Quality Engineering Associates). The evaluation criteria for feathering are as follows. The evaluation results are shown in Table 2.
A: Radgetness value was less than 13.
B: Radgetness value was 13 or more and less than 15.
C: Radgetness value was 15 or more.

(curl)
The following color ink and each reaction liquid were combined to form a set, and an image was recorded using these sets. Cyan ink extracted from PGI-2 Cyan (manufactured by Canon) and magenta ink extracted from PGI-2 Magenta (manufactured by Canon) are mounted on the cyan and magenta ink positions of the ink jet recording apparatus BJS700 (manufactured by Canon). did. First, each reaction solution was applied to a recording medium (trade name: office planner; manufactured by Canon) with an application roller. In this case, the application amount of the reaction liquid was 2 g / m ² . Immediately thereafter, a solid image of a secondary color was recorded with magenta ink and cyan ink on the recording medium coated with the reaction liquid. After the obtained recorded matter is left for 3 days in an environment of temperature 24 ° C./humidity 50% RH, the degree of curling of the recording medium is measured with a ruler from the leading edge of the recording medium to the grounding surface of the recording medium. It was evaluated by. The evaluation criteria for curl are as follows. The evaluation results are shown in Table 2.
AA: The distance from the leading end of the recording medium to the ground contact surface was 33 mm or less.
A: The distance from the front end of the recording medium to the ground contact surface was greater than 33 mm and not greater than 43 mm.
B: The distance from the leading edge of the recording medium to the ground contact surface was greater than 43 mm and 50 mm or less.
C: The distance from the leading edge of the recording medium to the ground contact surface was greater than 50 mm, or the leading edge of the recording medium was inward.

(High temperature storage)
Reaction liquids 1 and 2 were put in a Teflon (registered trademark) container and stored at 80 degrees for one week. Thereafter, the degree of yellowing of the liquid was visually observed, and the presence or absence of yellowing was shown in Table 2.

Claims (6)

A reaction liquid applied to a recording medium by a roller coating method prior to recording of ink containing a coloring material,
It has the function of destabilizing the dissolution or dispersion state of the coloring material in the ink by contacting with the ink, and at least the halogenated polyvalent metal, the acetylene glycol compound, and the average molecular weight are 200 or more, A reaction liquid characterized by containing 3,000 or less polyethylene glycol.   The reaction liquid according to claim 1, further comprising a polyhydric alcohol other than glycerin.   A set comprising a combination of an ink containing a color material and the reaction liquid according to claim 1.   3. An ink jet recording method in which a reaction liquid is applied to a recording medium by a roller coating method prior to recording of an ink containing a coloring material, and an image is formed by contacting the ink and the reaction liquid on the recording medium. An ink-jet recording method comprising using the reaction solution described in 1. The inkjet recording method according to claim 4, wherein an applied amount of the reaction liquid is 0.5 g / m ² or more and 3 g / m ² or less.   An ink jet recording apparatus comprising: an ink containing portion for containing ink; a recording head for ejecting ink; and a means for applying a reaction liquid to a recording medium by a roller coating method prior to ink recording. An ink jet recording apparatus, wherein the reaction liquid applied by the liquid applying means is the reaction liquid according to claim 1.

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