JP2020110996A - Inkjet recording method and inkjet recording device - Google Patents

Abstract

To provide an inkjet recording method that can record an image excellent in anti-marker performance while suppressing deterioration in discharge stability caused due to an ink receiving member.SOLUTION: The inkjet recording method comprises: a step of recording an image on a recording medium 1 by discharging aqueous ink through a discharge port of a recording head 3, on the basis of image data; and a step of discharging aqueous ink not used for recording the image through the discharge port to an ink receiving member 71. The aqueous ink contains resin having self-dispersion pigment and anionic group, and cation-ion exchange resin is arranged at a part contacting the aqueous ink, in the ink receiving member 71.SELECTED DRAWING: Figure 1

Description

The present invention relates to an inkjet recording method and an inkjet recording device.

2. Description of the Related Art In recent years, an inkjet recording method has been used to print a business sentence including characters and figures on a recording medium such as plain paper, and the frequency of use for such purposes has been remarkably increased. In such applications, a high level of quality and marker resistance are required for recorded images. In order to meet such a demand, for example, a water-based ink containing a water-soluble resin containing a self-dispersion pigment as a coloring material has been proposed (Patent Document 1).

In the inkjet recording method, an image is recorded on a recording medium by ejecting ink from an ejection port of a recording head. However, if ink or the like is clogged in the ejection port, or if the ink thickens in the flow path near the ejection port due to evaporation of the liquid component, normal ejection of the ink may be difficult. Therefore, an inkjet recording apparatus has been proposed that performs an operation of ejecting ink that is not used for recording to an ink receiving member (so-called preliminary ejection) after a lapse of a predetermined time since the ink was finally ejected (Patent Document 2).

JP, 2010-168466, A JP, 2016-175302, A

The present inventors examined images recorded using a water-based ink containing a water-soluble resin such as a resin having an anionic group and a self-dispersion pigment proposed in Patent Document 1 and the like. As a result, it was found that the recorded image had good marker resistance, but the image quality was not very good. The ink discharged to the ink receiving member becomes residual ink by evaporating the liquid component thereof. When an image is to be recorded again after the recording head is capped with the ink receiving member containing such residual ink, it is considered that the ink is difficult to be ejected normally and the quality of the recorded image is likely to deteriorate.

Therefore, an object of the present invention is to provide an ink jet recording method capable of recording an image having excellent marker resistance while suppressing a decrease in ejection stability caused by the ink receiving member. .. Another object of the present invention is to provide an inkjet recording apparatus used in this inkjet recording method.

That is, according to the present invention, a step of ejecting an aqueous ink from an ejection port of a recording head based on image data to record an image on a recording medium, and the aqueous ink not used for recording an image is ejected from the ejection port. A step of discharging to a receiving member, wherein the water-based ink contains a resin having a self-dispersion pigment and an anionic group, and in a portion of the ink receiving member that comes into contact with the water-based ink, An inkjet recording method is provided, which comprises a cation exchange resin.

According to the present invention, it is possible to provide an inkjet recording method capable of recording an image excellent in marker resistance while suppressing a decrease in ejection stability caused by an ink receiving member. Further, according to the present invention, it is possible to provide an inkjet recording apparatus used in this inkjet recording method.

It is a perspective view which shows typically one Embodiment of the inkjet recording device of this invention. It is a front view which expands a part of inkjet recording apparatus of FIG. 1, and is shown typically. It is a front view which expands a part of conventional ink jet recording device and shows it typically.

Hereinafter, the present invention will be described in more detail with reference to preferred embodiments. In the present invention, when the compound is a salt, the salt dissociates into ions and exists in the ink, but for convenience, it is expressed as “containing salt”. Further, a water-based ink for inkjet may be simply referred to as “ink”. The physical property values are values at normal temperature (25° C.) and normal pressure (1 atmospheric pressure) unless otherwise specified.

By using an ink containing a self-dispersion pigment and a resin having an anionic group, an image having high optical density and excellent marker resistance can be recorded. However, it has been found that it may be difficult to eject ink normally when an image is recorded again after the recording head is capped with the ink receiving member that has ejected the ink not used for recording. The viscosity of the ink discharged to the ink receiving member increases due to evaporation of liquid components such as water. Ink (residual ink, waste ink) in the ink receiving member whose viscosity has risen has low fluidity and is less likely to flow in the flow path connecting the ink receiving member to the recovery unit, so much remains in the ink receiving member. become. When the recording head is capped with an ink receiving member that has a large amount of residual ink remaining, liquid components evaporate from the ink existing in and near the ejection port until the relative humidity in the closed space formed by capping reaches an equilibrium state. It is considered that this increases the viscosity of the ink existing in and near the ejection port, making it difficult to eject the ink normally.

As a result of the study, the inventors of the present invention arranged a cation exchange resin in a portion of the ink receiving member that comes into contact with the ink, thereby suppressing deterioration in image quality caused by difficulty in normally ejecting the ink. The present invention has been completed and the present invention has been completed. The present inventors presume the mechanism by which such an effect is obtained as follows.

The ink containing the resin having an anionic group contains a cation which is a counter ion of the anionic group. The ink discharged to the ink receiving member comes into contact with the cation exchange resin. Cations in the ink are trapped in the cation exchange resin, and the concentration of cations in the ink decreases. The ink having a reduced concentration of cations is prevented from increasing in viscosity due to evaporation of a liquid component such as water, and therefore can easily flow from the ink receiving member to a flow path connected to the outside such as a recovery unit. Then, since the amount of ink (residual ink) remaining in the ink receiving member is reduced, even if the recording head is capped with the ink receiving member, evaporation of liquid components from the ink existing in the ejection port and its vicinity is suppressed. It As a result, it is considered that the ink is likely to be ejected normally and the deterioration of the image quality is suppressed.

<Inkjet recording method and inkjet recording apparatus>
The inkjet recording method of the present invention includes a step of recording an image on a recording medium by ejecting an aqueous ink from an ejection port of a recording head based on image data, and an ink receiving member for ejecting an aqueous ink not used for recording an image from the ejection port. And the step of discharging to. Further, the ink jet recording apparatus of the present invention includes a water-based ink, a recording head that is filled with the water-based ink, discharges the water-based ink from a discharge port based on image data, and records an image on a recording medium. And a receiving member. The ink receiving member is a member that receives the water-based ink that is discharged from the ejection port of the recording head and is not used for recording an image.

FIG. 1 is a perspective view schematically showing an embodiment of the inkjet recording apparatus of the present invention. As shown in FIG. 1, the inkjet recording apparatus according to the present embodiment includes a recording medium 1, a carriage 2, a recording head 3, a platen 4, a conveyance roller 5, a guide shaft 6, a paper discharge roller 12, and an ink receiving member 71. .. A platen 4, which is a support member, is provided at a position facing the ejection port surface of the recording head 3 over the moving region of the recording head 3. The recording operation is performed while the recording medium 1 is supported by the platen 4. Examples of the method of ejecting ink include a method of applying mechanical energy to the ink and a method of applying thermal energy to the ink.

The recording medium 1 is conveyed in a y1 direction intersecting the x direction by a conveying unit including a conveying roller 5 and a paper discharge roller 12. The transport roller 5 is provided on the upstream side of the platen 4 in the transport direction of the recording medium 1. The paper discharge roller 12 is provided on the downstream side of the platen 4 in the transport direction of the recording medium 1.

The recording head 3 is detachably mounted on the carriage 2. The carriage 2 reciprocates along the x direction. Specifically, the carriage 2 is movably supported along a guide shaft 6 arranged along the x direction, and is fixed to an endless belt (not shown) that moves in parallel with the guide shaft 6. .. The endless belt reciprocates by the driving force of the carriage motor, and thereby reciprocates the carriage 2 in the x direction. Then, the conveyance operation of the recording medium 1 by such a conveyance means and the recording operation performed based on the image data while moving the recording head 3 mounted on the carriage 2 in the direction intersecting the conveyance direction of the recording medium 1. An image is recorded on the recording medium 1 by repeating.

In the ink jet recording apparatus of the present embodiment, a recovery operation is performed in order to recover the state of the ejection port by removing the ink that has thickened due to evaporation of liquid components such as bubbles and water from the ejection port of the recording head 3. .. The recovery operation is an operation of ejecting ink, which is not used for recording an image, from the ejection port and discharging it to the ink receiving member 71 provided outside the recording area. As a method of discharging the ink, a method of applying mechanical energy or thermal energy to the ink (preliminary ejection) or a method of capping the recording head 3 with the ink receiving member 71 and depressurizing the inside of the ink receiving member 71 (suction) And so on. Ink ejection is performed based on preliminary ejection data, suction instructions, etc., separately from ink ejection based on print data.

(Ink receiving member)
FIG. 3 is a front view schematically showing an enlarged part of a conventional inkjet recording apparatus. An absorber 81 that can absorb ink is housed in an ink receiving member 71 that constitutes a conventional inkjet recording device. The ink discharged from the ejection port by the recovery operation is absorbed by the absorber 81 of the ink receiving member 71. The ink that has increased in viscosity due to the progress of evaporation of liquid components such as water in the absorber 81 is not sent to the recovery unit 11 even if the pump 9 is operated, and most of it becomes the residual ink 90 and the ink receiving member. Remains at 71. When the recording head 3 is capped with the ink receiving member 71 containing the residual ink 90, evaporation of liquid components such as water from the ink existing in the ejection port and its vicinity is promoted, and the ink thickens. If an image is to be recorded in such a state, it may be difficult for ink to be ejected normally, and the quality of the recorded image may deteriorate.

FIG. 2 is an enlarged schematic front view of a part of the inkjet recording apparatus of FIG. A cation exchange resin 80 is arranged in a portion of the ink receiving member 71 that comes into contact with the ink discharged from the ejection port of the recording head 3. When the ink discharged from the ejection port by the recovery operation comes into contact with the cation exchange resin 80 of the ink receiving member 71, the cations in the ink are trapped in the cation exchange resin 80, and the cation concentration in the ink decreases. As a result, the increase in the viscosity of the ink due to the evaporation of the liquid component such as water is suppressed, so that the ink can be sent to the waste ink recovery unit 11 through the flow path 10 by the operation of the pump 9.

(Water-based ink)
In the inkjet recording method of the present invention, an ink containing a self-dispersion pigment and a resin having an anionic group is used. The components constituting the ink will be described below.

[Self-dispersion pigment]
As a general pigment dispersion method, there are a resin dispersed pigment using a resin as a dispersant, and a self-dispersed pigment having a hydrophilic group bonded to the particle surface of the pigment. However, the coloring material contained in the ink used in the inkjet recording method of the present invention is a self-dispersion pigment. In the ink containing the resin-dispersed pigment, the dispersed state becomes unstable when contacted with the cation exchange resin, the pigment is likely to aggregate, and the viscosity may increase.

Examples of the pigment include inorganic pigments such as carbon black; organic pigments such as azo, phthalocyanine, quinacridone, isoindolinone, imidazolone, diketopyrrolopyrrole and dioxazine. As the carbon black, any carbon black such as furnace black, lamp black, acetylene black and channel black can be used.

As the self-dispersion pigment, one in which an anionic group such as a carboxylic acid group, a sulfonic acid group or a phosphonic acid group is bonded to the particle surface of the pigment directly or through another atomic group (-R-) is used. be able to. The anionic group may be either an acid type or a salt type, and when the anionic group is a salt type, it may be in a partially dissociated state or an all dissociated state. When the anionic group is a salt type, examples of the cation serving as a counter ion include an alkali metal cation, ammonium, organic ammonium and the like. Specific examples of the other atomic group (-R-) include a linear or branched alkylene group having 1 to 12 carbon atoms; an arylene group such as a phenylene group and a naphthylene group; a carbonyl group; an imino group; an amide group; a sulfonyl group. Group; ester group; ether group and the like. Moreover, the group which combined these groups may be sufficient.

The content (mass %) of the self-dispersion pigment in the ink is preferably 0.1 mass% or more and 15.0 mass% or less, based on the total mass of the ink, and 1.0 mass% or more and 10.0 mass% or less. % Or less is more preferable.

[Resin Having Anionic Group]
The resin having an anionic group is preferably an acrylic resin or a urethane resin. Examples of the anionic group include a carboxylic acid group, a sulfonic acid group, a phosphoric acid group and a phosphonic acid group.

The acrylic resin has, for example, a hydrophilic unit and a hydrophobic unit as constituent units. The hydrophilic unit is a unit having a hydrophilic group such as an anionic group. The hydrophilic unit can be formed, for example, by polymerizing a hydrophilic monomer having an anionic group. Specific examples of the hydrophilic monomer having an anionic group include acidic monomers having a carboxylic acid group such as (meth)acrylic acid, itaconic acid, maleic acid and fumaric acid; (meth)acrylic acid-2-ethylphosphonate and the like. Acid monomers having a phosphonic acid group; anionic monomers such as anhydrides and salts of these acidic monomers; hydroxy groups such as (meth)acrylic acid-2-hydroxyethyl and (meth)acrylic acid-3-hydroxypropyl Examples of the monomer include: Examples of the cation constituting the salt of the acidic monomer include ions such as lithium, sodium, potassium, ammonium and organic ammonium.

The hydrophobic unit is a unit that does not have a hydrophilic group such as an anionic group. The hydrophobic unit can be formed, for example, by polymerizing a hydrophobic monomer having no hydrophilic group such as an anionic group. Specific examples of the hydrophobic monomer include monomers having an aromatic ring such as styrene, α-methylstyrene, and benzyl (meth)acrylate; methyl (meth)acrylate, butyl (meth)acrylate, and (meth)acrylic acid 2 Examples thereof include (meth)acrylic acid ester-based monomers such as ethylhexyl. Further, a monomer having an alkylene oxide group may be used. The acrylic resin may be any of a random copolymer, a block copolymer, and a graft copolymer.

The urethane resin can be obtained, for example, by reacting polyisocyanate and polyol. In addition, a chain extender may be further reacted. When a urethane resin is used as the resin having an anionic group, it is preferable to incorporate a unit derived from a polyol having an acid group such as dimethylolpropionic acid or dimethylolbutanoic acid into the resin.

The acid value of the resin having an anionic group is preferably 5 mgKOH/g or more and 250 mgKOH/g or less. The weight average molecular weight of the resin having an anionic group is preferably 1,000 or more and 2,000,000 or less.

The content (mass %) of the resin having an anionic group in the ink is preferably 0.1 times or more in mass ratio with respect to the content (mass %) of the self-dispersion pigment. When the above mass ratio is less than 0.1 times, the marker resistance of the recorded image may be slightly lowered. The above mass ratio is preferably 10.0 times or less.

[First water-soluble organic solvent]
The ink preferably further contains a first water-soluble organic solvent. Then, determined by Fedors method, SP value of the first water-soluble organic solvent ^{((cal / cm 3) 1/2} ) and, SP value of the resin having an anionic group ^{((cal / cm 3) 1/2} ) The absolute value of the difference between and is preferably 3.0 or less. When the cation exchange resin and the ink come into contact with each other in the ink receiving member and the cations (H ⁺ ) of the cation exchange resin are exchanged with the cations in the ink, the hydrophilicity of the resin having an anionic group in the ink is increased. It may easily decrease. By including the first water-soluble organic solvent whose SP value has the above-described relationship with the SP value of the resin having an anionic group in the ink, the hydrophilicity of the resin having an anionic group is lowered. Can be suppressed. The absolute value of the difference is preferably 0.0 or more.

The SP value (δ: solubility parameter) in the present invention is a value calculated by the Fedors method based on the following formula (1). Regarding the SP value, the smaller the difference between the SP value of the solute and the SP value of the solvent, the greater the affinity of the solute for the solvent tends to be. The molar evaporation heat (ΔE _vap ) of the compound and the molar volume (V) of the compound at 25° C. can both be calculated by adding a fixed value belonging to atoms or groups in the molecule. It is general to use "cal" as the unit of SP value. When converting to the SI unit system, the relationship of “(cal/cm ³ ) ^1/2 =2.046×10 ³ (J/m ³ ) ^1/2 ” may be used.

（前記式（１）中、ΔＥ_ｖａｐは化合物のモル蒸発熱（ｃａｌ／ｍｏｌ）を表し、Ｖは２５℃における化合物のモル体積（ｃｍ^３／ｍｏｌ）を表す）

(In the formula (1), ΔE _vap represents the heat of vaporization of the compound (cal/mol), and V represents the molar volume of the compound at 25° C. (cm ³ /mol)).

Specific examples of the first water-soluble organic solvent include glycerin (16.4), trimethylolpropane (15.9), diethylene glycol (15.0), 1,2,6-hexanetriol (14.5), ethylene. Urea (14.2), 1,5-pentanediol (14.2), triethanolamine (13.7), triethylene glycol (13.6), 1,6-hexanediol (13.5), 2 -Pyrrolidone (12.6), 1,2-pentanediol (12.2), 1,2-hexanediol (11.8), diethylene glycol monobutyl ether (10.5), triethylene glycol monobutyl ether (10.3) ), polyethylene glycol 1000 (10.1), ethyl acetate (8.7), diethylene glycol diethyl ether (8.2) and the like. The numerical value in parentheses attached to each water-soluble organic solvent is the SP value calculated based on the formula (1).

The smaller the absolute value of the difference between the SP value of the resin having an anionic group and the SP value of the first water-soluble organic solvent, the greater the affinity between the resin having an anionic group and the first water-soluble organic solvent. The SP value of the resin having an anionic group can be calculated from the SP value of the units constituting the resin. Table 1 shows the SP values of the units derived from each monomer.

The SP value of the resin can be calculated as follows. First, a value is calculated by multiplying the SP value of each constituent unit of the target resin by the composition (mass) ratio of each constituent unit (composition ratio with the total being 1). Then, the SP values of the resin having an anionic group can be calculated by adding the calculated values. Hereinafter, the method for obtaining the SP value of the resin will be described by taking the acrylic resin 1 composed of styrene:acrylic acid (composition (mass) ratio=0.80:0.20) used in the examples as an example. From Table 1, the SP value of each unit of styrene and acrylic acid, which are units constituting the acrylic resin 1, is "10.6" and "14.0", respectively. Therefore, the SP value of the acrylic resin 1 can be obtained as follows.

SP value of acrylic resin =10.6×0.80+14.0×0.20=11.3 (cal/cm ³ ) ^1/2

The content (mass %) of the first water-soluble organic solvent in the ink is preferably 0.5 times or more in mass ratio with respect to the content (mass %) of the resin having an anionic group. When the above mass ratio is less than 0.5 times, the hydrophilicity of the resin having an anionic group in the ink tends to decrease when the cation exchange resin and the ink are contacted and the cations are exchanged. There are cases. Further, the above mass ratio is preferably 25.0 times or less. If the above mass ratio is more than 25.0 times, the resin having an anionic group easily penetrates into the recording medium together with the first water-soluble organic solvent, and the marker resistance of the image may be slightly lowered.

(Cation exchange resin)
A cation exchange resin is arranged in a portion of the ink receiving member that comes into contact with the ink discharged from the ejection port and not used for recording the image. The cation exchange resin is a strongly acidic or weakly acidic resin having the property of exchanging monovalent, divalent, or trivalent cations. The strongly acidic cation exchange resin has a chemical structure in which a sulfonic acid group is bonded to a crosslinked three-dimensional polymer matrix. The weakly acidic cation exchange resin has a chemical structure in which a carboxylic acid group is bonded to a polymer matrix. Since the strongly acidic cation exchange resin has a low acid dissociation constant, it may exchange up to the cations necessary for pigment dispersion in the ink when it comes into contact with the ink, which reduces the dispersibility of the pigment and reduces the viscosity of the ink. May easily rise. Therefore, it is preferable to use a weakly acidic cation exchange resin having a carboxylic acid group as the cation exchange resin.

The cation in the cation exchange resin may be any one that can suppress the increase in viscosity due to evaporation of the ink after contact with the cation exchange resin. Among them, the cation in the cation exchange resin is preferably H ⁺ .

As the cation exchange resin, a commercially available cation exchange resin can be used. Commercially available products of strongly acidic cation exchange resins are trade names of DIAMOND SK series (SK1B etc.), PK series (PK208 etc.), UBK series (UBK08 etc.); Amber light (IR120B etc.) etc. can be mentioned. Examples of commercially available weakly acidic cation exchange resins include Mitsubishi Chemical's Diaion WK10 series (WK10 etc.), WK40L; Dow Chemical's Amberlite (FPC3500 etc.), etc. under the following trade names. ..

The cation in the cation exchange resin can be replaced with another desired cation by a conventional method. For example, among the specific examples of the commercially available strong acid cation exchange resin described above, “SK1B” of DIAION SK series manufactured by Mitsubishi Chemical has a cation of Na ⁺ . Immerse "SK1B" in about 3 times the amount of 1 mol/L hydrochloric acid, gently stir for 10 minutes, remove the hydrochloric acid by decantation, and further wash with ion-exchanged water to remove cations (Na ⁺ ). It can be replaced with H ⁺ .

Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples, but the present invention is not limited to the following Examples as long as the gist thereof is not exceeded. Regarding the component amounts, those described as “part” and “%” are based on mass unless otherwise specified.

<Method of measuring acid value of resin>
The resin to be measured was dissolved in tetrahydrofuran to prepare a sample. Then, the acid value of the resin was measured by colloid titration using a potential difference using a potentiometric automatic titration device (trade name "AT-510", manufactured by Kyoto Electronics Manufacturing) equipped with a streaming potential titration unit (PCD-500). .. An ethanol solution of potassium hydroxide was used as a titration reagent.

<Method for measuring weight average molecular weight of resin>
The resin to be measured was dissolved in tetrahydrofuran at a temperature of 25° C. for 24 hours to prepare a solution. The obtained solution was filtered with a membrane filter to obtain a sample solution. The sample solution was adjusted so that the concentration of the component soluble in tetrahydrofuran was about 0.3%. Then, gel permeation chromatography (GPC) was performed under the following conditions to measure and calculate the weight average molecular weight of the resin. In calculating the weight average molecular weight of the resin, standard polystyrene resin (TSK standard polystyrene F-850, F-450, F-288, F-128, F-80, F-40, F-20, F-10, F -4, F-2, F-1, A-5000, A-2500, A-1000, A-500, manufactured by Tosoh Co., Ltd.) was used.
[Conditions for GPC]
Apparatus: Waters 2695 Separations Module, manufactured by Waters RI detector: 2414 detector, manufactured by Waters Column: KF-806M (4 stations), Showa Denko Eluent: Tetrahydrofuran (THF)
Flow rate: 1.0 mL/min
Oven temperature: 40°C
Sample injection volume: 100 μL

<Preparation of pigment dispersion>
(Pigment dispersion 1)
A solution prepared by dissolving 5.0 g of concentrated hydrochloric acid in 5.5 g of water was cooled to 5° C., and 1.55 g of 4-aminobenzoic acid was added in this state. The container containing this solution was put in an ice bath, and while stirring to maintain the temperature of the solution at 10° C. or lower, a solution obtained by dissolving 2.2 g of sodium nitrite in 9.0 g of ion-exchanged water at 5° C. added. After stirring for 15 minutes, 6 g of a pigment (carbon black, trade name “NIPex170IQ”, manufactured by Orion Engineered Carbons) was added with stirring. The mixture was further stirred for 15 minutes to obtain a slurry. The obtained slurry was filtered through a filter paper (trade name "Standard filter paper No. 2" manufactured by Advantech), the particles were thoroughly washed with water, and dried in an oven at 110°C. The dried particles were treated with hydrochloric acid, neutralized with an aqueous potassium hydroxide solution, and an appropriate amount of ion-exchanged water was added to adjust the pigment content. Thereby, -C ₆ H ₄ -COOK groups on the particle surface of the pigment self-dispersible pigment having attached to obtain a pigment dispersion liquid 1 in a state of being dispersed in water. The content of the pigment in the obtained pigment dispersion liquid 1 was 15.0%.

(Pigment dispersion 2)
Instead of 4-aminobenzoic acid, except for using 4-aminobenzenesulfonic acid 1.96 g, as in the case of a pigment dispersion liquid 1 described above, _-C 6 _H 4 -SO the particle surface of the pigment Pigment Dispersion Liquid 2 was obtained in which the self-dispersion pigment having ₃ K groups bonded thereto was dispersed in water. The content of the pigment in the obtained pigment dispersion liquid 2 was 15.0%.

(Pigment dispersion 3)
Instead of 4-aminobenzoic acid, except for using 1.96 g of 4-aminobenzenesulfonic acid, as in the case of a pigment dispersion liquid 1 described above, _-C 6 _H 4 -PO on the particle surface of the pigment A pigment dispersion liquid 3 in which a self-dispersion pigment having ₃ K ₂ groups bonded thereto was dispersed in water was obtained. The content of the pigment in the obtained pigment dispersion liquid 3 was 15.0%.

(Pigment dispersion 4)
Instead of 4-aminobenzoic acid, 4-aminophthalic acid was used to obtain 2.05 g, as in the case of a pigment dispersion liquid 1 described above, _-C 6 _H 3 on the particle surface of the pigment - (COOK) A pigment dispersion liquid 4 in which a self-dispersible pigment having _two groups bonded thereto was dispersed in water was obtained. The content of the pigment in the obtained pigment dispersion liquid 4 was 15.0%.

(Pigment dispersion 5)
C. I. A pigment dispersion liquid (trade name "CAB-O-JET250C", manufactured by Cabot) containing a self-dispersion pigment in which sulfonic acid groups are bonded via a benzene ring on the particle surface of Pigment Blue 15:4 is used as a pigment dispersion liquid 5. Using. The pigment content in Pigment Dispersion Liquid 5 was 15.0%.

(Pigment dispersion 6)
C. I. As a pigment dispersion liquid 6, a pigment dispersion liquid (trade name "CAB-O-JET265M", manufactured by Cabot) containing a self-dispersion pigment in which a sulfonic acid group is bonded to a particle surface of Pigment Red 122 via a benzene ring was used. .. The pigment content in Pigment Dispersion Liquid 6 was 15.0%.

(Pigment dispersion 7)
C. I. As a pigment dispersion liquid 7, a pigment dispersion liquid (trade name “CAB-O-JET270Y”, manufactured by Cabot) containing a self-dispersion pigment in which a sulfonic acid group was bonded via a benzene ring was used on the particle surface of Pigment Yellow 74. .. The pigment content in Pigment Dispersion Liquid 7 was 15.0%.

(Pigment dispersion 8)
Acrylic resin 1 (styrene-acrylic acid (composition ratio=80:20) copolymer, synthesis method described later) having an acid value of 156 mgKOH/g and a weight average molecular weight of 5,000 was neutralized with a 10% aqueous potassium hydroxide solution. 15.0 parts of pigment (carbon black, trade name "NIPex170IQ" manufactured by Orion Engineered Carbons), 7.5 parts of neutralized acrylic resin 1 (solid content), and 77.5 parts of ion-exchanged water are mixed. A mixture was obtained. The obtained mixture was dispersed for 1 hour using a sand grinder, and then centrifuged to remove coarse particles. Furthermore, pressure filtration was performed with a microfilter (manufactured by Fujifilm) having a pore size of 3.0 μm to obtain a pigment dispersion liquid 8 in which the pigment was dispersed in water with a resin dispersant (acrylic resin 1). The pigment content in Pigment Dispersion Liquid 8 was 15.0%, and the content of the resin dispersant was 7.5%.

<Synthesis of acrylic resin>
Using the types and amounts (%) of monomers shown in Table 2, acrylic resins 1 to 7 were synthesized by a conventional method. The anionic group is neutralized with a 10.0% aqueous potassium hydroxide solution, and an appropriate amount of ion-exchanged water is further added to obtain a liquid containing acrylic resins 1 to 7 having an acrylic resin content of 20.0%. Obtained. Table 2 shows the characteristics of the acrylic resin.

<Synthesis of urethane resin>
After dissolving the type and amount (%) of the polyol having no acid group shown in Table 3 in methyl ethyl ketone, the type and amount of the polyisocyanate shown in Table 3 and the polyol having the acid group were added, and reacted at 75° C. for 1 hour. To obtain a prepolymer solution. After cooling the obtained prepolymer solution to 60° C., an aqueous potassium hydroxide solution was added to neutralize the acid groups. The mixture was cooled to 40° C., ion-exchanged water was added, and the mixture was rapidly stirred with a homomixer to emulsify. The type and amount (%) of the chain extender shown in Table 3 were added, and the chain extension reaction was carried out at 30° C. for 12 hours. Analysis was performed using a Fourier transform infrared spectrophotometer (FT-IR), and when it was no longer possible to confirm the presence of isocyanate groups, heating and depressurization were performed to distill off methyl ethyl ketone. As a result, a liquid containing urethane resins 1 and 2 having a urethane resin content of 20.0% was obtained. Table 2 shows the characteristics of the urethane resin.

<Preparation of ink>
After mixing the components (unit: %) shown in the upper part of Tables 4-1 to 4-3 and thoroughly stirring, add with a membrane filter (trade name “HDCII filter”, manufactured by Pall) having a pore size of 2.5 μm. Each ink was prepared by pressure filtration. "Acetylenol E100" in Tables 4-1 to 4-3 is a trade name of a nonionic surfactant manufactured by Kawaken Fine Chemicals. In Tables 4-1 to 4-3, the numerical value in parentheses after each component name is the SP value (unit: (cal/cm ³ ) ^1/2 ) of each component. In the lower part of Tables 4-1 to 4-3, the content Cs (%) of the first water-soluble organic solvent, the content Cr (%) of the resin having an anionic group, and the value (times) of Cs/Cr are shown. Show.

<Evaluation>
An inkjet recording device (product name “PIXUSiP3100”, manufactured by Canon Inc.) that ejects ink from the recording head by the action of thermal energy was prepared. The resolution of this inkjet recording apparatus is 1200 dpi×1200 dpi, and the recording duty of an image recorded under the condition that one 5 pL ink droplet is applied to a unit area of 1200 inches×1200 inches is defined as 100%. A weakly acidic cation exchange resin (trade name "Diaion WK10", manufactured by Mitsubishi Chemical, positive ion: H ⁺ ) having a carboxylic acid group bonded thereto was mounted on the ink receiving member of this recording apparatus. However, in Example 26, the cation of a strongly acidic cation exchange resin (trade name "Diaion SK1B", manufactured by Mitsubishi Chemical, cation: Na ⁺ ) having a sulfonic acid group bonded thereto was converted into H ⁺ by a conventional method. Equipped with a replacement. In Comparative Example 3, the cation exchange resin was not mounted, and the absorber originally provided in the recording device was directly mounted on the ink receiving member. In order to prevent the spherical cation exchange resin having a diameter of about 1 mm from moving within the ink receiving member, the cation exchange resin mounted was covered with a stainless mesh filter.

Each of the prepared inks was filled in an ink cartridge and mounted in the above-mentioned inkjet recording device, and each evaluation shown below was performed. In the evaluation criteria of each evaluation item shown below, "AA", "A", and "B" were set as acceptable levels, and "C" was set as an unacceptable level. The evaluation results are shown in Table 5.

(Discharge stability)
The following evaluations were performed in an environment of a temperature of 30°C and a relative humidity of 10%. After mounting an ink cartridge filled with ink on the above-mentioned ink jet recording apparatus, cleaning (recovery operation) was carried out from the printer driver, and the ink was sufficiently discharged into the ink receiving member. After recording the nozzle check pattern of the recording apparatus and confirming that ink was ejected from all the ejection ports, 120 nozzle check patterns were recorded at a speed of 2 sheets per minute. It was confirmed from the finally recorded nozzle check pattern that ink was ejected from all ejection ports, and the recording head was left capped with an ink receiving member for 24 hours. After being left standing, a nozzle check pattern was recorded to visually check the ink ejection state from the ejection port, and the ejection stability was evaluated according to the following evaluation criteria.

AA: Ink was ejected from all ejection ports.
A: There were less than 4 ejection ports that could not eject ink normally.
B: There were 4 or more and less than 8 ejection ports that could not eject ink normally.
C: Eight or more ejection ports were not able to eject ink normally.

(Marker resistance)
The following evaluation was performed under the environment of a temperature of 23° C. and a relative humidity of 55%. Using the above inkjet recording device, vertical ruled lines having a thickness of 1/10 inch were recorded on plain paper (trade name "PPC paper GF-500", manufactured by Canon Inc.). Five minutes after recording, the vertical ruled lines were marked with a yellow line marker (trade name "OPTEX2", manufactured by Zebra), and immediately after that, marking was performed on the non-recorded portion of plain paper. The state of stains on the pen tip of the marker and the non-recording portion was visually confirmed, and the marker resistance was evaluated according to the following evaluation criteria.

A: The pen tip was clean, and the non-recording area was clean.
B: The pen tip was slightly stained, but the non-recorded area was hardly stained.
C: The pen tip was stained, and the non-recording area was also stained.

1: Recording medium 2: Carriage 3: Recording head 6: Guide shaft 71: Ink receiving member 80: Cation exchange resin 81: Absorber 90: Residual ink

Claims (5)

Discharging an aqueous ink from an ejection port of a recording head based on image data to record an image on a recording medium; and discharging the aqueous ink not used for recording an image from the ejection port to an ink receiving member, An inkjet recording method having:
The water-based ink contains a resin having a self-dispersion pigment and an anionic group,
An ink jet recording method, wherein a cation exchange resin is arranged in a portion of the ink receiving member that comes into contact with the water-based ink. The water-based ink further contains a first water-soluble organic solvent,
Determined by Fedors method, the first water-soluble organic SP value of the solvent ^{((cal / cm 3) 1/2} ) and, the SP value of the resin having the anionic group ^{((cal / cm 3) 1/2} ) The ink jet recording method according to claim 1, wherein the absolute value of the difference between and is 3.0 or less. 3. The content (mass %) of the first water-soluble organic solvent in the aqueous ink is 0.5 times or more a mass ratio with respect to the content (mass %) of the resin having an anionic group. The inkjet recording method described in 1. The inkjet recording method according to any one of claims 1 to 3, wherein the cation exchange resin is a cation exchange resin having a carboxylic acid group. A water-based ink, a recording head that is filled with the water-based ink therein, discharges the water-based ink from a discharge port based on image data to record an image on a recording medium, and is discharged from the discharge port And an ink receiving member that receives the water-based ink not used for recording,
The water-based ink contains a resin having a self-dispersion pigment and an anionic group,
An ink jet recording apparatus, wherein a cation exchange resin is arranged in a portion of the ink receiving member that comes into contact with the water-based ink.

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